US20010003435A1 - Angle sensor which makes it possible to prevent rattling caused by backlash between gears inside the angle sensor - Google Patents
Angle sensor which makes it possible to prevent rattling caused by backlash between gears inside the angle sensor Download PDFInfo
- Publication number
- US20010003435A1 US20010003435A1 US09/729,614 US72961400A US2001003435A1 US 20010003435 A1 US20010003435 A1 US 20010003435A1 US 72961400 A US72961400 A US 72961400A US 2001003435 A1 US2001003435 A1 US 2001003435A1
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- United States
- Prior art keywords
- gear
- angle sensor
- fitting
- rotary shaft
- plate spring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000001514 detection method Methods 0.000 claims description 46
- 238000013459 approach Methods 0.000 claims description 2
- 230000002093 peripheral effect Effects 0.000 description 14
- 229920003002 synthetic resin Polymers 0.000 description 6
- 239000000057 synthetic resin Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000005452 bending Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
- F16H55/02—Toothed members; Worms
- F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears
- F16H55/24—Special devices for taking up backlash
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D15/00—Steering not otherwise provided for
- B62D15/02—Steering position indicators ; Steering position determination; Steering aids
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C10/00—Adjustable resistors
- H01C10/30—Adjustable resistors the contact sliding along resistive element
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D2205/00—Indexing scheme relating to details of means for transferring or converting the output of a sensing member
- G01D2205/20—Detecting rotary movement
- G01D2205/28—The target being driven in rotation by additional gears
Definitions
- the present invention relates to an angle sensor which detects, for example, the steering angle of a steering wheel of an automobile, and,, more particularly, to an angle sensor which can detect the angle of rotation of the steering wheel with high precision as a result of preventing rattling caused by backlash between gears or between a gear and a screw shaft inside the angle sensor.
- FIG. 8 is a plan view showing the internal structure of a conventional angle sensor proposed in U.S. patent application No. 09-477971 by the inventor of the angle sensor in the application concerned.
- the conventional angle sensor is used to detect, for example, the steering angle of a steering wheel of an automobile with high precision.
- a rotary member 3 is provided inside a case 2 formed of a synthetic resin material such as plastic.
- the rotary member 3 is a cylindrically shaped member formed of, for example, a synthetic resin material, and is rotatably supported with respect to the case 2 .
- the steering wheel of an automobile is inserted into the rotary member 3 , and the rotary member 3 rotates clockwise and counterclockwise along with the steering wheel.
- a plurality of helical gears 3 a are formed along the entire outer peripheral surface of the rotary member 3 .
- a rotary shaft 9 is rotatably provided inside the case 2 , with the illustrated X dimension being defined as the center axis thereof.
- a driving gear 8 is secured to the rotary shaft 9 .
- a plurality of helical gears 8 a are formed along the entire outer peripheral surface of the driving gear 8 , and engage the helical gears 3 a of the rotary member 3 .
- the rotary shaft 9 is formed of a metallic material such as brass or aluminum, and has a spiral thread groove 9 a formed from the center to one end thereof.
- a detecting member 4 is provided at the rotary shaft 9 .
- the detecting member 4 has a through hole formed therein from one end surface to the other end surface thereof in the direction of movement (that is, in the X dimension). Threads (not shown) which engage the thread groove 9 a formed in the rotary shaft 9 are formed in the inner peripheral surface defining the through hole.
- a second magnet 5 B is mounted to the bottom surface of the detecting member 4 by, for example, insert molding. The detecting member 4 is guided in the interior of the case 2 so as to move in a straight line in the X dimension. When the rotary member 3 rotates, the driving gear 8 and the rotary shaft 9 rotate, causing the detecting member 4 and the second magnet 5 B to reciprocate in the X dimension.
- the driving of the driving gear 8 is reduced in correspondence with the amount of rattling caused by the backlash, causing hysteresis resulting from the direction of rotation to occur, whereby the amount of error is increased.
- the rotary shaft 9 has a simple beam structure in which both ends thereof are supported, so that, when a biasing force acts, the displacement of the portion corresponding to where the rotary member 3 and the driving gear 8 engage (that is, the center portion) is displaced the greatest, with the displacement becoming smaller towards both ends of the rotary shaft 9 .
- the rate of change of the strength of the magnetic field in the Z dimension with respect to the distance of movement of the second magnet 5 B and the detecting member 4 is no longer linear with respect to the direction of movement.
- the distance between the first magnet 5 A and the first Hall element 6 A changes so that a predetermined output can no longer be obtained. Therefore, the distance of movement of the detecting member 4 can no longer be detected precisely, so that the precision with which the angle of rotation (that is, the steering angle) of the rotary member 3 (or the steering wheel) is detected is decreased.
- the detecting member 4 and the screw shaft 9 a are constructed so that only the screw shaft 9 a engages the threads formed in the through hole 4 a of the detecting hole 4 . Therefore, play (that is, backlash) tends to occur between the threads of the detecting member 4 and the thread grooves of the thread groove 9 a. The backlash tends to result in rattling of the detecting member 4 in the axial direction (that is, the X dimension), so that a precise distance of movement in accordance with the angle of rotation of the rotary member 3 cannot be obtained by the detecting member 4 . Therefore, the Hall element 6 B can no longer be used to detect with high precision the angle of rotation of a shaft to be detected, such as a steering wheel.
- an angle sensor for detecting an angle of rotation of a first rotary shaft by a detecting operation of a detecting portion.
- the angle sensor comprises a first gear which rotates in accordance with the first rotary shaft, a second rotary shaft which extends in a direction perpendicular to the first rotary shaft, a second gear which rotates along with the second rotary shaft and which engages the first gear, a third gear which is rotatably provided at the second rotary shaft and which engages the first gear, and the detecting portion which detects the rotation of the second rotary shaft.
- the biasing member may exert a biasing force onto the second gear in a direction of rotation thereof.
- the biasing member may exert a biasing force in a direction in which the second gear approaches the first gear.
- the second gear that is, a driving gear
- the third gear that is, an auxiliary gear
- the first gear that is, a rotary member
- the biasing member so that a tooth of the second gear as well as a tooth of the third gear resiliently presses against a tooth of the first gear.
- the second rotary shaft rotates similarly to the second gear.
- the second gear it is possible for the second gear to always drive the second rotary shaft while the second gear resiliently presses against the first gear at all times. This makes it possible to eliminate rattling caused by backlash between the first and second gears. Consequently, the rotational force which is applied to the rotary member from the steering wheel can be transmitted to the driving gear with high efficiency, thereby allowing the angle of rotation of the steering wheel to be detected with high precision.
- the first gear and the second gear may engage each other at an intersection point where an imaginary normal line from the center of rotation of the first gear vertically intersects the second rotary shaft, and the third gear may be provided at a location situated away from the intersection point.
- the third gear may be a helical gear having an inverted spherical surface.
- the first and second gears can be disposed in a row with the second rotary shaft, so that they can be disposed in a smaller area.
- an angle sensor for detecting an angle of rotation of a first rotary shaft as a result of a detecting operation by a detecting member.
- the angle sensor comprises a first gear which rotates in accordance with the first rotary shaft, a screw shaft which extends in a direction perpendicular to the first rotary shaft, a second gear which rotates with the screw shaft and which engages the first gear, a fitting member which engages the screw shaft and which moves in an axial direction of the screw shaft by a rotational force of the screw shaft, a detection member to be detected which moves along with the fitting member, a detection portion to be detected provided at the detection member, and a detecting member for detecting a linear movement of the detection portion.
- the fitting member and the detection member are connected together by a plate spring, and the fitting member is supported by the plate spring.
- a plate thickness direction of the plate spring is oriented in a direction perpendicular to a direction of movement of the fitting member and the detection member.
- the plate spring is secured to the fitting member and the detection member in the direction perpendicular to the direction of movement of the fitting member and the detection member and at a location where a gap is formed in a plate surface direction.
- the plate spring is secured along a line facing the direction of movement of the fitting member and the detection member.
- the plate thickness direction (that is, a surface direction) of the plate spring faces the resiliency dimension (that is, the Z dimension) of the plate spring, and the fitting member and the detection member are secured along a line which extends in the resiliency dimension of the plate spring. This prevents the plate spring from becoming twisted, thereby allowing the fitting member to be stably fitted to the screw shaft, so that the detection member can be reliably moved.
- a mounting surface of the plate spring for mounting to the fitting member and a mounting surface of the plate spring for mounting to the detection member may be located in the same plane.
- the angle sensor can be made thinner.
- the fitting member may comprise a U-shaped fitting portion which opens in a direction perpendicular to a plane of the plate spring, the fitting portion engaging the screw shaft.
- an opening can be formed in a portion of the fitting portion by forming the fitting portion into a U shape in cross section. Therefore, it is possible to easily perform mounting and dismounting operations of the screw shaft and the fitting portion through this opening.
- the fitting member comprises a U-shaped fitting portion which opens in, a direction perpendicular to a plane of the plate spring, and the fitting portion engages the screw shaft
- the fitting member may comprise a pair of the fitting portions which are separated from each other in the direction of movement thereof.
- the plate spring may have a cutaway portion formed in the center portion thereof, and the pair of fitting portions may be biased towards the screw shaft by an area of the plate spring where the cutaway portion is not formed.
- the pair of fitting portions can be independently pushed against the screw shaft, so that they can stably press against the screw shaft without tilting.
- the angle sensor may further comprise a guiding member for guiding the movement of the detection member in an axial direction thereof.
- the guiding member has at least one rail which is provided parallel to the screw shaft. The detection member slides on the at least one rail.
- one rail or two or more rails may be used.
- the detection member can move smoothly in a straight line with respect to a detecting means (that is, a Hall element).
- Two of the rails parallel to each other may be provided along the direction of movement, and the fitting member may be located substantially at the center of a region between the two rails.
- the load of the holder which holds the detecting member can be distributed uniformly on the two rails, so that it is possible to prevent problems such as tilting of the holder and derailment of a slider of the holder from the rails from occurring. Therefore, it is possible to always move the detection member parallel to the detecting member, thereby allowing very small angles of the first rotary shaft which is a detect shaft (that is, a steering wheel) to be stably detected.
- FIG. 1 is a front sectional view of the internal structure of an angle sensor in accordance with the present invention.
- FIG. 2 is an exploded perspective view of the main portion of the angle sensor.
- FIG. 3 is an enlarged sectional view of the main portion of the angle sensor.
- FIG. 4 is a schematic sectional view taken along line 4 - 4 in FIG. 3.
- FIG. 5 is a sectional view taken along line 5 - 5 in FIG. 1.
- FIG. 6 is an enlarged sectional view taken along line 6 - 6 in FIG. 5.
- FIG. 7 is a sectional view of another embodiment of an angle sensor.
- FIG. 8 is a plan view of the internal structure of a conventional angle sensor.
- FIG. 1 is a front sectional view of the internal structure of a first embodiment of an angle sensor in accordance with the present invention.
- the angle sensor is used to detect, for example, the steering angle of a steering wheel of an automobile with high precision.
- FIG. 2 is an exploded perspective view of the main portion of the angle sensor.
- FIG. 3 is an enlarged sectional view of the main portion of the angle sensor.
- FIG. 4 is a schematic sectional view taken along line 4 - 4 in FIG. 3.
- FIG. 5 is a sectional view taken along line 5 - 5 in FIG. 1.
- FIG. 6 is an enlarged sectional view taken along line 6 - 6 in FIG. 5.
- reference numeral 12 denotes a case
- reference numeral 13 denotes a rotary member (or a first gear).
- the rotary member 13 is a cylindrically shaped member formed of a synthetic resin material, and is supported inside the case 12 so as to be rotatable in the illustrated clockwise direction (that is, in the ⁇ 1 direction) and the illustrated counterclockwise direction (that is, in the ⁇ 2 direction).
- a hollow is formed in the center of the rotary member 13 .
- a steering wheel Sh that is, a first rotary shaft of an automobile is inserted into this hollow (see FIG. 2).
- Axially extending protrusions 13 a and 13 b are formed on the inner peripheral surface of the rotary member 13 , and can be fitted into recesses (not shown) formed in the outer peripheral surface of the steering wheel Sh.
- the rotary member 13 is also rotated.
- a helical gear 13 A having teeth obliquely cut at an angle of approximately 45° from an axial dimension (that is, the Y dimension) is formed along the outer peripheral surface of the rotary member 13 .
- a unit case 17 is provided at the lower portion of the case 12 (in the Z 2 direction in FIG. 1).
- the unit case 17 is formed of synthetic resin subjected to, for example, injection molding, and is mounted at the bottom portion of the case 12 , as shown in FIG. 1.
- Supports 17 a and 17 b which extend in the illustrated Z 1 direction are formed at both ends of the unit case 17 in the X 1 and X 2 directions, with circular supporting portions 17 a 1 and 17 b 1 being formed in ends of the corresponding supports 17 a and 17 b.
- Cutaway portions 17 a 2 and 17 b 2 which are openings in the edges of the corresponding supporting portions 17 a 1 and 17 b 1 are formed in the top portions of the supporting portions 17 a 1 and 17 b 1 .
- Both ends of a rotary shaft 30 can be mounted in the supporting portions 17 a 1 and 17 b 1 through the cutaway portions 17 a 2 and 17 b 2 .
- a support 17 c, first base 17 d, and a second base 17 e are provided between the supports 17 a and 17 b.
- the auxiliary support 17 c is disposed beside the illustrated right support 17 a.
- the auxiliary support 17 c may be disposed beside, for example, the illustrated left support 17 b, or between the first base 17 d and the second base 17 e.
- the first base 17 d is formed into a substantially V shape.
- a pair of Hall elements H 1 that is, detecting members
- the second base 17 e is a rectangular parallelepiped which extends in the illustrated X dimension.
- Rails 17 e 1 and 17 e 2 which have protruding shapes in cross section are formed on both sides of the top surface of the second base 17 e so as to extend in the X dimension.
- a Hall element H 2 (that is, a detecting member) is provided in the interior of the second base 17 e while its external form is positioned.
- a detection member 20 to be detected which is slidable in the X dimension opposes the top portion of the second base 17 e.
- An MR element, a magnetic flux detecting coil, or the like may be used in place of the Hall elements H 1 and the Hall element H 2 .
- the detection member 20 comprises a holder 21 , a plate spring 22 , and a fitting member 23 .
- the holder 21 is formed of synthetic resin, and has a planar rectangular space 21 A formed therein.
- Four sliders 21 a which protrude in the illustrated Y dimension are provided at the four corners of the holder 21 which enclose the space 21 A.
- the bottom surface of each slider 21 a is a smooth surface having a small coefficient of friction, with the widthwise distances between the bottom surfaces of the sliders 21 a (that is, the distances between opposing bottom surfaces of the sliders 21 a in the Y dimension) being the same as the widthwise distance between the rails 17 e 1 and 17 e 2 . While the sliders 21 a of the holder 21 are placed on the rails 17 e 1 and 17 e 2 , the holder 21 can reciprocate in the illustrated X dimension.
- a second magnet M 2 (that is, a detection member to be detected) formed of a magnetic material such as ferrite which is magnetized so as to have a pair of N and S poles along the axial direction is held in the space 21 A in the holder 21 , with the magnetized surface of the second magnet M 2 and the Hall element H 2 opposing each other.
- a securing portion 21 f is provided at the illustrated Y side of the holder 21 . Protrusions 21 g and 21 h which protrude in the illustrated Z 1 direction are formed on the securing portion 21 f.
- the plate spring 22 and the fitting member 23 are provided at the top portion of the space 21 A.
- the plate spring 22 is formed by pressing and/or punching, or bending one piece of thin metallic plate or resin plate.
- the illustrated Y 1 side (that is, the fixed-end-side) surface of the plate spring 22 is a mounting surface 22 A
- the illustrated Y 2 side (that is, the free-end-side) surface is a mounting surface 22 B.
- the mounting surfaces 22 A and 22 B are joined together through a bent portion.
- a square cutaway portion 22 C is formed in the center portion of the plate spring 22 .
- Cross-shaped cuts 22 a and 22 b are formed in the mounting surface 22 A of the plate spring 22 along the direction of movement of the detection member 20 (that is, in the X dimension).
- the Y 1 -side mounting surface 22 A of the plate spring 22 is secured to the securing portion 21 f of the holder 21 . Accordingly, the plate spring 22 is supported by the securing portion 21 f in a cantilever arrangement.
- Positioning holes 22 c and 22 d are formed in both ends of the free-end-side mounting surface 22 B along the direction of movement of the detection member 20 (that is, in the X dimension).
- Supporting arms 22 f and 22 f whose ends are bent in the Z 1 direction and which extend in the illustrated Y 1 direction in the cutaway portion 22 C, and supporting arms 22 f and 22 f whose ends are also bent in the Z 1 direction and which extend in the Y 2 direction in the cutaway portion 22 C are integrally formed between the holes 22 c and 22 d.
- the fitting member 23 is secured onto the mounting surface 22 B of the plate spring 22 so that the longitudinal direction of the fitting member 23 is parallel to the direction of movement of the detection member 20 (that is, to the X dimension).
- the fitting member 23 is formed of a resin material, and a through hole is formed in both ends of a base 23 A in the X 1 and X 2 directions, from one end surface to the other end surface of a column.
- a pair of hollow, semi-columnar fitting portions 23 a and 23 b are also formed in both sides of the fitting member 23 by cutting the column in a plane parallel to the XY plane. In other wards, the fitting portions 23 a and 23 b are formed into U shapes in cross section. Internal threads are formed in inside surfaces 23 c and 23 c of the corresponding fitting portions 23 a and 23 b.
- Small-diameter protrusions 23 d and 23 e having shapes similar to those of the protrusions 21 g and 21 h of the holder 21 are formed con the back surface (that is, the Z 2 -side surface) of the base 23 A of the fitting member 23 so as to protrude in the illustrated Z 2 direction (see FIG. 6).
- the fitting member 23 is firmly held by the mounting surface 22 B, whereby the fitting member 23 is held by the free end of the plate spring 22 .
- the fitting member 23 is secured to the mounting surface 22 B of the plate spring 22 , the fitting member 23 is placed directly above the space 21 A of the holder 21 .
- the fitting member 23 is resiliently supported in the illustrated Z 1 direction so as to resiliently press against a screw shaft 30 a (described later).
- the holder 21 and the fitting member 23 are secured along the direction of movement of the detection member 20 (that is, along the X dimension). In other words, the holder 21 and the fitting member 23 are secured such that the longitudinal directions thereof are parallel to the direction of movement of the detection member 20 .
- the plate spring 22 can be held by the fitting member 23 , and these can be easily mounted to the holder 21 , the assembly operation can be easily carried out.
- a driving gear 36 (that is, a second gear) is secured to the rotary shaft 30 (that is, a second rotary shaft) so as to be rotatable with the rotary shaft 30 .
- a helical gear 36 A having the same module as the helical gear 13 A formed along the outer peripheral surface of the rotary member 13 is formed along the outer peripheral surface of the driving gear 36 .
- the screw shaft 30 a which has a helical shape is formed from the portion of the rotary shaft 30 adjacent to the driving gear 36 to the left end of the rotary shaft 30 .
- the pitch between thread grooves of the screw shaft 30 a is the same as the pitch of the internal threads formed in the inside surfaces 23 c and 23 c of the corresponding fitting portions 23 a and 23 b.
- the fitting member 23 can be biased horizontally in the Z 1 direction. Therefore, it is possible to prevent the production of tilted biasing force with respect to the screw shaft 30 a, at both ends of the fitting portions 23 a and 23 b. Therefore, the screw shaft 30 a can be resiliently pressed against the fitting portions 23 a and 23 b with a uniform biasing force. Consequently, the screw shaft 30 a and the inside surfaces 23 c and 23 c of the corresponding fitting portions 23 a and 23 b can uniformly closely contact each other, making it possible to reduce rattling therebetween.
- the biasing force of the plate spring 22 pushes the fitting member 23 onto the screw shaft 30 a, and the holder 21 towards the second base 17 e (that is, in the illustrated Z 2 direction).
- the fitting member 23 is set so as to be positioned at about the center of the region between the two rails 17 e 1 and 17 e 2
- the load of the holder 21 which holds the second magnet M 2 is substantially uniformly distributed onto the two rails 17 e 1 and 17 e 2 through each of the sliders 21 a. This makes it possible to prevent the occurrence of problems such as tilting of the holder 21 and derailment of the sliders 21 a from the rails 17 e 1 and 17 e 2 .
- a fat axially extending portion 36 a and a thin axially extending portion 36 b which extend along the axial center portion of the driving gear 36 in the X 1 direction are formed at the illustrated right end side of the driving gear 36 .
- the thin axially extending portion 36 b is formed continuously with the fat axially extending portion 36 a in the illustrated X 1 direction.
- An auxiliary gear (that is, a third gear) 40 is rotatably inserted onto the fat axially extending portion 36 a.
- a biasing member 50 A is provided between the right end surface of the driving gear 36 and the auxiliary gear 40 .
- the biasing member 50 A used in the embodiment shown in FIGS. 1 and 2 is, for example, a torsion spring 50 .
- One end 50 a of the biasing member 50 A is formed so as to extend in the illustrated X 2 direction, and is inserted into an insertion hole 36 c formed in the driving gear 36 as shown in FIG. 3.
- the other end 50 b of the biasing member 50 A is caught by a catching portion 40 a formed in an opposing surface of the auxiliary gear 40 . It is mounted in a twisted state so as to have a small inside diameter. In addition, it is subjected to a force sufficient to cause rotation of the rotary shaft 30 . Further, it is mounted in a flexed state in the axial direction.
- a helical gear 40 A is formed along the outer peripheral surface of the auxiliary gear 40 . More specifically, the outside diameter of the side of the auxiliary gear 40 opposing the driving gear 36 is smaller than the outside diameter of the opposite side of the auxiliary gear 40 .
- the portion between these sides of the gear 40 A is a helical gear-shaped portion having an inverted spherical surface having a diametrical curvature equal to that of the helical gear 13 A formed at the outer peripheral surface of the rotary member 13 .
- the teeth of the auxiliary gear 40 in axial cross section are helical along a circumferential direction of the rotary member 13 .
- the auxiliary gear 40 is formed so that it reliably engages the gear of the rotary member 13 at a location situated away from an imaginary normal line O-O′ in the illustrated X 1 direction (see FIG. 3).
- the auxiliary gear 40 may be a bevel gear in which the teeth thereof in axial cross section are linearly tilted along the circumferential direction of the rotary member 13 .
- An annular washer 55 and a first magnet M 1 are provided at the illustrated right end side of the auxiliary gear 40 .
- the inside diameter of the first magnet M 1 is substantially equal to the outside diameter of the thin axially extending portion 36 b of the driving gear 36 .
- the first magnet M 1 can be secured to the rotary shaft 30 by fitting the first magnet M 1 onto the thin axially extending portion 36 b.
- Both surfaces of the washer 55 are smooth surfaces having a small coefficient of friction. Sliding friction between an end surface of the auxiliary gear 40 and an end surface of the first magnet M 1 can be reduced by interposing the washer 55 between the auxiliary gear 40 and the first magnet M 1 . In order to prevent the auxiliary gear 40 and the first magnet M 1 from becoming dislodged, it is preferable that a speed nut 56 be provided so as to contact the end surface of the first magnet M 1 and the end surface of the driving gear 36 .
- the rotary shaft 30 having the driving gear 36 , the auxiliary gear 40 , the biasing member 50 A, the washer 55 , and the magnet M 1 formed thereat is supported between the supporting portion 17 a 1 of the support 17 a and the supporting portion 17 b 1 of the support 17 b.
- bearings 60 and 60 are mounted to both ends of the rotary shaft 30 , respectively.
- the bearings 60 and 60 are molded out of synthetic resin material.
- Each bearing 60 comprises a cylindrical bearing portion 61 and a flange 62 formed on one surface of the corresponding bearing portion 61 .
- the magnet M 1 is set opposing the inclined surfaces of the substantially V-shaped portion of the first base 17 d.
- the fitting portions 23 a and 23 b of the fitting member 23 engage the screw shaft 30 a.
- the driving gear 36 is disposed between the first base 17 d and the sliding second base 17 e.
- the unit case 17 having the rotary shaft 30 and the like mounted thereat is secured at the bottom portion of the inside of the case 12 .
- the helical gear 13 A of the rotary member 13 and the helical gear 36 A of the driving gear 36 engage each other in a screw gear relationship.
- the center of the driving gear 36 is set so as to be situated at an intersection point Q where a perpendicular line (that is, the imaginary normal line O-O′) extending downward towards the rotary shaft 30 (that is, the second rotary shaft) from the center O of the rotary member 13 (that is, from the center axis of the steering wheel or first rotary shaft) and the rotational center axis of the rotary shaft 30 intersect each other.
- the auxiliary gear (that is, the third gear) 40 is set at a location situated away from the intersection point Q in the illustrated X 1 direction.
- the outer peripheral surface of the auxiliary gear 40 comprises the helical gear 40 A having an inverted spherical shape, so that, as shown in FIG. 1 and FIG. 3, the curved sectional shape lies along the pitch circle of the rotary member 13 . Therefore, even at a location situated away from the intersection point. Q in the illustrated X 1 direction, it is possible to engage the inverted spherical, helical gear 40 A of the auxiliary gear 40 and the helical gear 13 A of the rotary member 13 . It is preferable that the crests of the teeth of the inverted spherical, helical gear 40 A and the helical gears 13 A and 36 A have involute curved surfaces.
- the driving gear 36 Since the driving gear 36 is firmly fitted to the rotary shaft 30 , it cannot move in the axial direction.
- the auxiliary gear 40 is inserted onto the rotary shaft 30 through the driving gear 36 so as to be relatively rotatably held through the rotary shaft 30 .
- the axial movement of the auxiliary gear 40 is restricted by the washer 50 , the first magnet M 1 , and the speed nut 56 .
- the biasing member 50 A provided between the driving gear 36 and the auxiliary gear 40 applies biasing force to the driving gear 36 in the ⁇ 2 direction, and biasing force to the auxiliary gear 40 in the ⁇ 1 direction. Therefore, as shown in FIG.
- a tooth surface 40 A 1 of the helical gear 40 A of the auxiliary gear 40 contacts a tooth surface 13 A 1 of the helical gear 13 A of the rotary member 13 from the ⁇ 1 direction.
- the auxiliary gear 40 is positioned as a result of being resiliently pressed by the biasing member 50 A in the axial direction (that is, the X 2 direction). Therefore, even if the helical gears, that is, tapered surfaces contact each other, sliding between both tooth surfaces does not occur, so that both of the helical gears are stably in close contact with each other.
- a biasing force (that is, a rotational force) is exerted onto the driving gear 36 in the ⁇ 2 direction. Since, as mentioned above, the auxiliary gear 40 and the rotary shaft 30 rotate relative to each other, the driving gear 36 provided at the rotary shaft 30 is rotated until a tooth surface 36 A 1 of the helical gear 36 A comes into contact with a tooth surface 13 A 2 of the helical gear 13 A of the rotary gear 13 . Even here, the driving gear 36 is similarly positioned in the axial direction (that is, the X 2 direction), so that axial sliding between the teeth of the helical gears does not occur, whereby they stably resiliently press against each other.
- the biasing member 50 A exerts rotational forces acting in opposite directions onto the driving gear 36 and the auxiliary gear 40 .
- the tooth surface 36 A 1 of the helical gear 36 A of the driving member 36 and the tooth surface 40 A 1 of the helical gear 40 A of the auxiliary gear 40 resiliently sandwich both tooth surfaces 13 A 1 and 13 A 2 of the helical gear 13 A of the rotary member 13 from both directions (that is, the ⁇ 1 and ⁇ 2 directions).
- the screw shaft 30 a engages the fitting portions 23 a and 23 b of the fitting member 23 .
- the fitting portions 23 a and 23 b are resiliently pressed against the screw shaft 30 a in the Z 1 direction by the biasing force of the plate spring 22 , so that backlash between the screw shaft 30 a and the inside surfaces 23 c and 23 c of the corresponding fitting portions 23 a and 23 b can be reduced.
- the rotary member 13 rotates in correspondence with this rotation.
- a rotational force in the illustrated ⁇ 2 direction acts on the auxiliary gear 40 and the driving gear 36 engaging the rotary member 13 , so that the rotary shaft 30 and the first magnet M 1 are set so as to rotate eight times in the illustrated ⁇ 2 direction.
- the outer peripheral surface of the first magnet M 1 is magnetized so that the N pole and the S pole pass by the Hall elements H 1 once or twice each time the first magnet M 1 rotates once. Accordingly, the pair of Hall elements H 1 provided at the V-shaped first base 17 d opposing the first magnet M 1 detect changes in the strength of the magnetic field of the magnet M 1 , making it possible to detect the rotational direction and very small rotational angles of the rotary member 13 .
- the screw shaft 30 a of the rotary shaft 30 causes an advancing force in either the illustrated X 1 direction or X 2 direction (that is, in either one of the thrust directions) to act on the fitting portions 23 a and 23 b used for the holder 21 .
- This causes the sliders 21 a of the holder 21 to slide on the rails 17 e 1 and 17 e 2 of the second base 17 e and to move linearly in either the illustrated X 1 direction or X 2 direction.
- the screw shaft 30 a of the rotary shaft 30 and the fitting portions 23 a and 23 b of the fitting member 23 are converting portions for converting the rotational movement of the rotary shaft 30 in either the ⁇ 1 or the ⁇ 2 direction into linear movement.
- the converting portions cause the detection member 20 to move in either the X 1 or X 2 direction in order to output a signal which varies linearly within the entire rotational angle range of the steering wheel Sh.
- the plate spring 22 biases the fitting member 23 horizontally in order to prevent rattling between the screw shaft 30 a of the rotary shaft 30 and the inside surfaces 23 c and 23 c of the corresponding fitting portions 23 a and 23 b, so that the detection member 20 which moves in accordance with the rotation of the screw shaft 30 a advances with higher precision.
- the linearity between the angle of rotation of the rotary member 13 and the distance of movement of the detection member 20 can be enhanced.
- the Hall element H 2 can generate an output which precisely corresponds to (or is proportional to) the angle of rotation of the rotary member 13 .
- the fitting portions 23 a and 23 b are formed into U shapes so that the top portions thereof are open, making it possible to easily assemble the screw shaft 30 a and the fitting portions 23 a and 23 b.
- FIG. 7 is a sectional view of the main portion of another embodiment of an angle sensor.
- a biasing member 50 B is provided between an auxiliary gear 40 and a washer 55 instead of providing the biasing member 50 A between the driving gear 36 and the auxiliary gear 40 as in the first embodiment.
- a rotary member 13 and a driving gear 36 include a helical gear 13 A and a helical gear 36 A, respectively, and an auxiliary gear 40 comprises a screw-cap-shaped gear 40 A.
- the rotary member 13 and the driving gear 36 , and the rotary member 13 and the auxiliary gear 40 engage each other in a, screw gear relationship.
- the rotations of the auxiliary gear 40 in the ⁇ 1 and ⁇ 2 directions are restricted, so that movements in only the X 1 and X 2 directions are possible.
- the biasing member 50 B is, for example, a coil spring or a plate spring, and biases the auxiliary gear 40 towards the driving gear 36 (that is, in the illustrated X 2 direction).
- a tapered or inverted spherical, helical gear 40 A is provided at the outer peripheral surface of the auxiliary gear 40 similarly to the above, so that, when it is biased towards the driving gear 36 , the helical gear 40 A of the auxiliary gear 40 can engage the helical gear 13 A of the rotary member 13 .
- the helical gear 40 A while rotating the rotary member 30 moves along a tapered surface of the helical gear 13 A in the axial direction (that is, the X 2 direction) so that gaps are not produced at the portion where the helical gear 40 A of the auxiliary gear 40 and the helical gear 13 A of the rotary member 13 contact each other and at the portion where the helical gear 13 A and the helical gear 36 A of the driving gear 36 contact each other. Therefore, one surface of the helical gear 13 A of the rotary member 13 and one surface of the helical gear 36 A of the driving gear 36 are always kept in contact with each other, making it possible to prevent rattling caused by backlash therebetween.
- the rotational force of the rotary member 13 can be efficiently transmitted to the driving gear 36 , so that the linearity of the holder 21 can be increased, making it possible to detect the angle of rotation of the steering wheel Sh with high precision.
- a gap is prevented from being formed at the portion where the helical gear 13 A of the rotary member 13 and the helical gear 36 A of the driving gear 36 contact each other by incorporating a biasing member 50 A so that it is flexed in the inside diameter direction and axial direction
- this may be achieved by incorporating the biasing member 50 A so that it is flexed in either the axial direction or the inside diameter direction.
- the biasing member 50 A may be incorporated so as to spread in the axial direction.
- the biasing member 50 A In the case where the biasing member 50 A is only flexed in the axial direction, it is preferable that the biasing member 50 A not be positioned in the direction of rotation with respect to at least one of the auxiliary gear 40 and the driving gear 36 . In this case, a tooth surface of the driving gear 36 and a tooth surface of the auxiliary gear 40 slide along the tooth surfaces of the helical gear 13 A, as a result of which the auxiliary gear 40 and the driving gear 36 rotate. Thus, it is possible to expect this embodiment to provide advantages similar to those provided by the first embodiment.
- the biasing member 50 A In the case where the biasing member 50 A is only flexed in the inside diameter direction, it is preferable that the biasing member 50 A not be positioned in the axial direction with respect to at least one of the auxiliary gear 40 and the driving gear 36 . In this case, a tooth surface of the driving gear 36 and a tooth surface of the auxiliary gear 40 slide along the tooth surfaces of the helical gear 13 A, as a result of which the auxiliary gear 40 moves axially so that its location is fixed. Thus, it is possible to expect this embodiment to provide advantages similar to those provided by the first embodiment.
- the biasing member 50 A is incorporated so as to spread in the axial direction, the axial location of the auxiliary gear 40 is restricted by the driving gear 36 .
- a tooth surface 40 A 2 of the helical gear 40 A and a tooth surface 13 A 2 of the helical gear 13 A are always in contact with each other, and a tooth surface 36 A 2 of the helical gear 36 A and a tooth surface 13 A 1 of the gear 13 A are always in contact with each other.
- the biasing member 50 A is incorporated so as to be flexed in both the inside diameter direction and the axial direction, and the auxiliary gear 40 is rotatably held with respect to the rotary shaft 30 .
- the axial movement of the auxiliary gear 40 is prescribed, and, with the location where the auxiliary gear 40 and the rotary member 13 contact each other serving as a reference, the driving gear 36 is biased towards the rotary member 13 .
- the auxiliary gear 40 may be joined to the rotary shaft 30 through splines, and the axial movement of the auxiliary gear 40 may be such as not to be restricted.
- the biasing member 50 A it is preferable that the biasing member 50 A not be positioned in the direction of rotation with respect to at least one of the auxiliary gear 40 and the driving gear 36 .
- the helical gear 40 A while rotating the rotary shaft 30 moves axially along a tapered surface of the helical gear 13 A so that no gaps are created at the portion where the helical gear 13 A and the helical gear 40 A of the auxiliary gear 40 contact each other and at the portion where the helical gear 13 A and the helical gear 36 A of the driving gear 36 contact each other. Therefore, a tooth surface of the helical gear 13 A of the rotary member 13 and a tooth surface of the helical gear 36 A of the driving gear 36 are always in contact with each other, so that rattling caused by backlash therebetween does not occur.
- biasing member 50 A is provided between the driving gear 36 and the auxiliary gear 40
- a biasing member may be disposed between the auxiliary gear 40 and the washer 55 as a result of holding the washer 55 and the driving gear 36 so that they rotate integrally.
- the fitting portions 23 a and 23 b of the fitting member 23 and the thread grooves of the screw shaft 30 a contact each other at the contact portions is increased by forming the fitting portions 23 a and 23 b as separate portions at both ends of the fitting member 23
- the fitting portions 23 a and 23 b may be integrally formed from one end to the other end of the fitting member 23 .
- the plate spring 22 and the holder 21 , and the plate spring 22 and the fitting member 23 are joined together through cuts and protrusions at two locations, they may be joined together at at least two or more locations or by bonding the whole surfaces thereof.
- two rails 17 e 1 and 17 e 2 are provided on the second base 17 e, one rail or three or more rails may be used as long as the detection member 20 can be moved linearly in the direction of movement.
- the cuts 22 a and 22 b are cross-shaped, they may be formed as holes or holes having cross-shaped cuts formed therearound in order to be fitted onto the corresponding protrusions 21 g and 21 h.
- the plate spring is held by inserting the cuts 22 a and 22 b onto the corresponding protrusions 21 h and 21 g, the plate spring 22 may be held by the holder 21 by insert molding.
- mounting structures other than that described above may be used as long as the plate spring 22 is positioned and held by the holder 21 without any rattling of the plate spring 22 with respect to the holder 21 .
- the cutaway portion 22 C is square, it may have a shape which separates the portion between the cuts 22 a and 22 b or the portion between the holes 22 c and 22 d.
- the mounting surfaces 22 A and 22 B of the plate spring 22 are flat surfaces, ribs may be formed thereon along the axial direction, or ends thereof may be bent at bending lines parallel to the axial line in order to increase the twisting strength without affecting the flexed portion of the plate spring 22 .
- the degree with which the screw shaft and the fitting portions contact each other can be increased, making it possible to decrease rattling which tends to occur therebetween. Therefore, the detection member can be advanced in the axial direction thereof with higher precision, making it possible to detect the angle of rotation of the first: rotary shaft with high precision.
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Abstract
An angle sensor in which, when a biasing member is used, a biasing force in the β2 direction acts on a driving gear, and a biasing force in the β1 direction acts on an auxiliary gear. This prevents backlash from occurring between a rotary member and the driving member, making it possible to reduce rattling between the rotary member and the driving member. A fitting member is provided at the free end side of a resilient supporting member in order to resiliently press a screw shaft in the Z1 direction. Therefore, internal threads of inside surfaces of corresponding fitting portions of the fitting member and thread grooves of the screw shaft can be made to uniformly closely contact each other, making it possible reduce rattling caused by backlash therebetween. Consequently, the angle of rotation of a steering wheel which is mounted to the rotary member is detected with high precision.
Description
- 1. Field of the Invention
- The present invention relates to an angle sensor which detects, for example, the steering angle of a steering wheel of an automobile, and,, more particularly, to an angle sensor which can detect the angle of rotation of the steering wheel with high precision as a result of preventing rattling caused by backlash between gears or between a gear and a screw shaft inside the angle sensor.
- 2. Description of the Related Art
- FIG. 8 is a plan view showing the internal structure of a conventional angle sensor proposed in U.S. patent application No. 09-477971 by the inventor of the angle sensor in the application concerned. The conventional angle sensor is used to detect, for example, the steering angle of a steering wheel of an automobile with high precision.
- In an
angle sensor 1 shown in FIG. 8, arotary member 3 is provided inside acase 2 formed of a synthetic resin material such as plastic. Therotary member 3 is a cylindrically shaped member formed of, for example, a synthetic resin material, and is rotatably supported with respect to thecase 2. The steering wheel of an automobile is inserted into therotary member 3, and therotary member 3 rotates clockwise and counterclockwise along with the steering wheel. A plurality ofhelical gears 3 a are formed along the entire outer peripheral surface of therotary member 3. - A
rotary shaft 9 is rotatably provided inside thecase 2, with the illustrated X dimension being defined as the center axis thereof. Adriving gear 8 is secured to therotary shaft 9. A plurality ofhelical gears 8 a are formed along the entire outer peripheral surface of thedriving gear 8, and engage thehelical gears 3 a of therotary member 3. Therotary shaft 9, is formed of a metallic material such as brass or aluminum, and has aspiral thread groove 9 a formed from the center to one end thereof. A detectingmember 4 is provided at therotary shaft 9. - The detecting
member 4 has a through hole formed therein from one end surface to the other end surface thereof in the direction of movement (that is, in the X dimension). Threads (not shown) which engage thethread groove 9 a formed in therotary shaft 9 are formed in the inner peripheral surface defining the through hole. Asecond magnet 5B is mounted to the bottom surface of the detectingmember 4 by, for example, insert molding. The detectingmember 4 is guided in the interior of thecase 2 so as to move in a straight line in the X dimension. When therotary member 3 rotates, thedriving gear 8 and therotary shaft 9 rotate, causing the detectingmember 4 and thesecond magnet 5B to reciprocate in the X dimension. - A
Hall element 6B is provided at a side opposing thesecond magnet 5B, on afixing member 7 in thecase 2. A magnetizedfirst magnet 5A is integrally mounted to the outer circumferential surface of therotary shaft 9. Asecond Hall element 6A is provided on thefixing member 7 so as to oppose the outer circumferential surface of thefirst magnet 5A. - When the
rotary shaft 9 rotates with the rotation of therotary member 3, thefirst magnet 5A rotates, causing a sine wave to be output. At the same time, thesecond magnet 5B reciprocates in the X dimension, causing values which change linearly through the entire rotational angle range of the steering wheel to be output. By detecting these values, the absolute position of the steering wheel resulting from the angle of rotation (that is, the steering angle) can be detected. - When an attempt is made to detect the angle of rotation (that is, the steering angle) of the steering wheel with high precision using the above-described
angle sensor 1, the problem of rattling due to backlash between thehelical gears 3 a of therotary member 3 and thehelical gears 8 a of thedriving gear 8 arises. - More specifically, in the above-described
angle sensor 1, the rotation of therotary member 3 is detected, or the detectingmember 4 is moved in the X dimension after changing the rotational movement to linear movement. Therefore, when the backlash between thehelical gears 3 a of therotary member 3 and thehelical gears 8 a of thedriving gear 8 is too large, the rattling therebetween causes an error to be produced in the distance of movement of the detectingmember 4 which is moved in the X dimension. Here, when the direction of rotation of the rotary member 3 (or the steering wheel) changes, the driving of thedriving gear 8 is reduced in correspondence with the amount of rattling caused by the backlash, causing hysteresis resulting from the direction of rotation to occur, whereby the amount of error is increased. - In the
conventional angle sensor 1, backlash which occurs between the gears is decreased by increasing the degree with which thehelical gears 3 a of therotary member 3 and thehelical gears 8 a of thedriving gear 8 contact each other by biasing, for example, either therotary member 3 in the Z2 direction towards thedriving gear 8 or thedriving gear 8 in the Z1 direction towards therotary member 3. - However, when the degree with which the
rotary member 3 and thedriving gear 8 contact each other is increased to the extent that rattling does not occur, the biasing force produced between the gears becomes too large, so that rotational torque becomes large, and therotary shaft 9 gets distorted due to, for example, thermal expansion, making it impossible to smoothly guide the detectingmember 4 in the X dimension. In addition, therotary shaft 9 has a simple beam structure in which both ends thereof are supported, so that, when a biasing force acts, the displacement of the portion corresponding to where therotary member 3 and thedriving gear 8 engage (that is, the center portion) is displaced the greatest, with the displacement becoming smaller towards both ends of therotary shaft 9. Therefore, the rate of change of the strength of the magnetic field in the Z dimension with respect to the distance of movement of thesecond magnet 5B and the detectingmember 4 is no longer linear with respect to the direction of movement. In addition, the distance between thefirst magnet 5A and thefirst Hall element 6A changes so that a predetermined output can no longer be obtained. Therefore, the distance of movement of the detectingmember 4 can no longer be detected precisely, so that the precision with which the angle of rotation (that is, the steering angle) of the rotary member 3 (or the steering wheel) is detected is decreased. - In the above-described
conventional angle sensor 1, the detectingmember 4 and thescrew shaft 9 a are constructed so that only thescrew shaft 9 a engages the threads formed in the throughhole 4 a of the detectinghole 4. Therefore, play (that is, backlash) tends to occur between the threads of the detectingmember 4 and the thread grooves of thethread groove 9 a. The backlash tends to result in rattling of the detectingmember 4 in the axial direction (that is, the X dimension), so that a precise distance of movement in accordance with the angle of rotation of therotary member 3 cannot be obtained by the detectingmember 4. Therefore, theHall element 6B can no longer be used to detect with high precision the angle of rotation of a shaft to be detected, such as a steering wheel. - To overcome the aforementioned conventional problems, it is an object of the present invention to provide an angle sensor which can detect the angle of rotation of a rotary member with high precision as a result of decreasing backlash between a driving gear and a gear of the rotary member.
- It is also another object of the present invention to provide an angle sensor in which a detecting member which reciprocates in accordance with the rotation of a screw shaft is advanced with high precision.
- To these ends, according to a first aspect of the present invention, there is provided an angle sensor for detecting an angle of rotation of a first rotary shaft by a detecting operation of a detecting portion. The angle sensor comprises a first gear which rotates in accordance with the first rotary shaft, a second rotary shaft which extends in a direction perpendicular to the first rotary shaft, a second gear which rotates along with the second rotary shaft and which engages the first gear, a third gear which is rotatably provided at the second rotary shaft and which engages the first gear, and the detecting portion which detects the rotation of the second rotary shaft. In the angle sensor, the first gear engages the second gear and the third gear in a screw gear relationship, and a biasing member is provided at the second rotary shaft. The biasing member causes a tooth of the first gear to be sandwiched between a tooth of the second gear and a tooth of the third gear.
- In one form of the first aspect of the invention, the biasing member may exert a biasing force onto the second gear in a direction of rotation thereof.
- It another form of the first aspect of the invention, the biasing member may exert a biasing force in a direction in which the second gear approaches the first gear.
- In the invention, the second gear (that is, a driving gear) and the third gear (that is, an auxiliary gear) are disposed at the first gear (that is, a rotary member) through the biasing member, so that a tooth of the second gear as well as a tooth of the third gear resiliently presses against a tooth of the first gear. Here, the second rotary shaft rotates similarly to the second gear.
- Accordingly, it is possible for the second gear to always drive the second rotary shaft while the second gear resiliently presses against the first gear at all times. This makes it possible to eliminate rattling caused by backlash between the first and second gears. Consequently, the rotational force which is applied to the rotary member from the steering wheel can be transmitted to the driving gear with high efficiency, thereby allowing the angle of rotation of the steering wheel to be detected with high precision.
- In still another form of the first aspect of the invention, the first gear and the second gear may engage each other at an intersection point where an imaginary normal line from the center of rotation of the first gear vertically intersects the second rotary shaft, and the third gear may be provided at a location situated away from the intersection point.
- By virtue of this structure, the rotational force of the first gear can be transmitted to the second gear with precision and with high efficiency.
- When the first gear and the second gear engage each other at an intersection point where an imaginary normal line from the center of rotation of the first gear vertically intersects the second rotary shaft, and when the third gear is provided at a location situated away from the intersection point, the third gear may be a helical gear having an inverted spherical surface.
- By virtue of this structure, the first and second gears can be disposed in a row with the second rotary shaft, so that they can be disposed in a smaller area.
- According to a second aspect of the present invention, there is provided an angle sensor for detecting an angle of rotation of a first rotary shaft as a result of a detecting operation by a detecting member. The angle sensor comprises a first gear which rotates in accordance with the first rotary shaft, a screw shaft which extends in a direction perpendicular to the first rotary shaft, a second gear which rotates with the screw shaft and which engages the first gear, a fitting member which engages the screw shaft and which moves in an axial direction of the screw shaft by a rotational force of the screw shaft, a detection member to be detected which moves along with the fitting member, a detection portion to be detected provided at the detection member, and a detecting member for detecting a linear movement of the detection portion. In the angle sensor, the fitting member and the detection member are connected together by a plate spring, and the fitting member is supported by the plate spring. In addition, a plate thickness direction of the plate spring is oriented in a direction perpendicular to a direction of movement of the fitting member and the detection member. Further, the plate spring is secured to the fitting member and the detection member in the direction perpendicular to the direction of movement of the fitting member and the detection member and at a location where a gap is formed in a plate surface direction. The plate spring is secured along a line facing the direction of movement of the fitting member and the detection member.
- In the invention, the plate thickness direction (that is, a surface direction) of the plate spring faces the resiliency dimension (that is, the Z dimension) of the plate spring, and the fitting member and the detection member are secured along a line which extends in the resiliency dimension of the plate spring. This prevents the plate spring from becoming twisted, thereby allowing the fitting member to be stably fitted to the screw shaft, so that the detection member can be reliably moved.
- In one form of the second aspect of the invention, a mounting surface of the plate spring for mounting to the fitting member and a mounting surface of the plate spring for mounting to the detection member may be located in the same plane.
- By virtue of this structure, the angle sensor can be made thinner.
- In another form of the second aspect of the invention, the fitting member may comprise a U-shaped fitting portion which opens in a direction perpendicular to a plane of the plate spring, the fitting portion engaging the screw shaft.
- In the above-described structure, an opening can be formed in a portion of the fitting portion by forming the fitting portion into a U shape in cross section. Therefore, it is possible to easily perform mounting and dismounting operations of the screw shaft and the fitting portion through this opening.
- When the fitting member comprises a U-shaped fitting portion which opens in, a direction perpendicular to a plane of the plate spring, and the fitting portion engages the screw shaft, the fitting member may comprise a pair of the fitting portions which are separated from each other in the direction of movement thereof. In addition, the plate spring may have a cutaway portion formed in the center portion thereof, and the pair of fitting portions may be biased towards the screw shaft by an area of the plate spring where the cutaway portion is not formed.
- By virtue of this structure, the pair of fitting portions can be independently pushed against the screw shaft, so that they can stably press against the screw shaft without tilting.
- In still another form of the second aspect of the invention, the angle sensor may further comprise a guiding member for guiding the movement of the detection member in an axial direction thereof. The guiding member has at least one rail which is provided parallel to the screw shaft. The detection member slides on the at least one rail.
- In other words, one rail or two or more rails may be used. When a rail or rails which are parallel to the screw shaft are provided, the detection member can move smoothly in a straight line with respect to a detecting means (that is, a Hall element).
- Two of the rails parallel to each other may be provided along the direction of movement, and the fitting member may be located substantially at the center of a region between the two rails.
- By virtue of this structure, the load of the holder which holds the detecting member can be distributed uniformly on the two rails, so that it is possible to prevent problems such as tilting of the holder and derailment of a slider of the holder from the rails from occurring. Therefore, it is possible to always move the detection member parallel to the detecting member, thereby allowing very small angles of the first rotary shaft which is a detect shaft (that is, a steering wheel) to be stably detected.
- FIG. 1 is a front sectional view of the internal structure of an angle sensor in accordance with the present invention.
- FIG. 2 is an exploded perspective view of the main portion of the angle sensor.
- FIG. 3 is an enlarged sectional view of the main portion of the angle sensor.
- FIG. 4 is a schematic sectional view taken along line4-4 in FIG. 3.
- FIG. 5 is a sectional view taken along line5-5 in FIG. 1.
- FIG. 6 is an enlarged sectional view taken along line6-6 in FIG. 5.
- FIG. 7 is a sectional view of another embodiment of an angle sensor.
- FIG. 8 is a plan view of the internal structure of a conventional angle sensor.
- Hereunder, a description of the present invention will be given with reference to the drawings.
- FIG. 1 is a front sectional view of the internal structure of a first embodiment of an angle sensor in accordance with the present invention. The angle sensor is used to detect, for example, the steering angle of a steering wheel of an automobile with high precision. FIG. 2 is an exploded perspective view of the main portion of the angle sensor. FIG. 3 is an enlarged sectional view of the main portion of the angle sensor. FIG. 4 is a schematic sectional view taken along line4-4 in FIG. 3. FIG. 5 is a sectional view taken along line 5-5 in FIG. 1. FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. 5.
- In an
angle sensor 10 shown in FIG. 1,reference numeral 12 denotes a case, andreference numeral 13 denotes a rotary member (or a first gear). Therotary member 13 is a cylindrically shaped member formed of a synthetic resin material, and is supported inside thecase 12 so as to be rotatable in the illustrated clockwise direction (that is, in the α1 direction) and the illustrated counterclockwise direction (that is, in the α2 direction). A hollow is formed in the center of therotary member 13. A steering wheel Sh (that is, a first rotary shaft) of an automobile is inserted into this hollow (see FIG. 2).Axially extending protrusions rotary member 13, and can be fitted into recesses (not shown) formed in the outer peripheral surface of the steering wheel Sh. When the steering wheel Sh is rotated, therotary member 13 is also rotated. In addition, as shown in FIG. 2, ahelical gear 13A having teeth obliquely cut at an angle of approximately 45° from an axial dimension (that is, the Y dimension) is formed along the outer peripheral surface of therotary member 13. - A
unit case 17 is provided at the lower portion of the case 12 (in the Z2 direction in FIG. 1). Theunit case 17 is formed of synthetic resin subjected to, for example, injection molding, and is mounted at the bottom portion of thecase 12, as shown in FIG. 1.Supports unit case 17 in the X1 and X2 directions, with circular supportingportions 17 a 1 and 17 b 1 being formed in ends of the corresponding supports 17 a and 17 b.Cutaway portions 17 a 2 and 17 b 2 which are openings in the edges of the corresponding supportingportions 17 a 1 and 17 b 1 are formed in the top portions of the supportingportions 17 a 1 and 17b 1. Both ends of a rotary shaft 30 (described later) can be mounted in the supportingportions 17 a 1 and 17 b 1 through thecutaway portions 17 a 2 and 17b 2. Asupport 17 c,first base 17 d, and asecond base 17 e are provided between thesupports - In the embodiment, the
auxiliary support 17 c is disposed beside the illustratedright support 17 a. However, theauxiliary support 17 c may be disposed beside, for example, the illustrated leftsupport 17 b, or between thefirst base 17 d and thesecond base 17 e. - As shown in FIGS. 1 and 2, the
first base 17 d is formed into a substantially V shape. A pair of Hall elements H1 (that is, detecting members) are provided at the back sides of inclined surfaces of the V-shaped portion (that is, in the interior of thefirst base 17 d) while their external forms are positioned. Thesecond base 17 e is a rectangular parallelepiped which extends in the illustrated X dimension.Rails 17e e 2 which have protruding shapes in cross section are formed on both sides of the top surface of thesecond base 17 e so as to extend in the X dimension. As shown in FIGS. 1, 5 and 6, a Hall element H2 (that is, a detecting member) is provided in the interior of thesecond base 17 e while its external form is positioned. Adetection member 20 to be detected which is slidable in the X dimension opposes the top portion of thesecond base 17 e. An MR element, a magnetic flux detecting coil, or the like may be used in place of the Hall elements H1 and the Hall element H2. - The
detection member 20 comprises aholder 21, aplate spring 22, and afitting member 23. Theholder 21 is formed of synthetic resin, and has a planarrectangular space 21A formed therein. Foursliders 21 a which protrude in the illustrated Y dimension are provided at the four corners of theholder 21 which enclose thespace 21A. The bottom surface of eachslider 21 a is a smooth surface having a small coefficient of friction, with the widthwise distances between the bottom surfaces of thesliders 21 a (that is, the distances between opposing bottom surfaces of thesliders 21 a in the Y dimension) being the same as the widthwise distance between therails 17e e 2. While thesliders 21 a of theholder 21 are placed on therails 17e e 2, theholder 21 can reciprocate in the illustrated X dimension. - A second magnet M2 (that is, a detection member to be detected) formed of a magnetic material such as ferrite which is magnetized so as to have a pair of N and S poles along the axial direction is held in the
space 21A in theholder 21, with the magnetized surface of the second magnet M2 and the Hall element H2 opposing each other. A securingportion 21 f is provided at the illustrated Y side of theholder 21.Protrusions portion 21 f. - The
plate spring 22 and thefitting member 23 are provided at the top portion of thespace 21A. Theplate spring 22 is formed by pressing and/or punching, or bending one piece of thin metallic plate or resin plate. The illustrated Y1 side (that is, the fixed-end-side) surface of theplate spring 22 is a mountingsurface 22A, whereas the illustrated Y2 side (that is, the free-end-side) surface is a mountingsurface 22B. The mountingsurfaces square cutaway portion 22C is formed in the center portion of theplate spring 22.Cross-shaped cuts surface 22A of theplate spring 22 along the direction of movement of the detection member 20 (that is, in the X dimension). When theprotrusions holder 21 are inserted into and firmly fitted in thecorresponding cuts side mounting surface 22A of theplate spring 22 is secured to the securingportion 21 f of theholder 21. Accordingly, theplate spring 22 is supported by the securingportion 21 f in a cantilever arrangement. The (Y2--side) mountingsurface 22B is the free end, and the plate thickness direction of the plate spring 22 (that is, the direction of the normal line in a plane= the illustrated Z dimension) is the resiliency direction. Positioning holes 22 c and 22 d are formed in both ends of the free-end-side mounting surface 22B along the direction of movement of the detection member 20 (that is, in the X dimension). Supportingarms cutaway portion 22C, and supportingarms cutaway portion 22C are integrally formed between theholes - As shown in FIG. 2, the
fitting member 23 is secured onto the mountingsurface 22B of theplate spring 22 so that the longitudinal direction of thefitting member 23 is parallel to the direction of movement of the detection member 20 (that is, to the X dimension). Thefitting member 23 is formed of a resin material, and a through hole is formed in both ends of abase 23A in the X1 and X2 directions, from one end surface to the other end surface of a column. A pair of hollow, semi-columnarfitting portions fitting member 23 by cutting the column in a plane parallel to the XY plane. In other wards, thefitting portions fitting portions - Small-
diameter protrusions 23 d and 23 e having shapes similar to those of theprotrusions holder 21 are formed con the back surface (that is, the Z2-side surface) of thebase 23A of thefitting member 23 so as to protrude in the illustrated Z2 direction (see FIG. 6). By inserting theprotrusions 23 d and 23 e into the correspondingholes surface 22B of theplate spring 22, and positioning them, and caulking the supportingarms base 23A of thefitting member 23, thefitting member 23 is firmly held by the mountingsurface 22B, whereby thefitting member 23 is held by the free end of theplate spring 22. - Accordingly, when the
fitting member 23 is secured to the mountingsurface 22B of theplate spring 22, thefitting member 23 is placed directly above thespace 21A of theholder 21. By the resilient force of theplate spring 22, thefitting member 23 is resiliently supported in the illustrated Z1 direction so as to resiliently press against ascrew shaft 30 a (described later). - In the same plane as the
plate spring 22 formed of one plate, and at both ends (that is, the Y-side fixed end and the Y2-side free end) of theplate spring 22 separated by a gap in a direction (that is, the Y dimension or a plate surface direction) perpendicular to the direction of movement of the detection member 20 (that is, the X dimension), theholder 21 and thefitting member 23 are secured along the direction of movement of the detection member 20 (that is, along the X dimension). In other words, theholder 21 and thefitting member 23 are secured such that the longitudinal directions thereof are parallel to the direction of movement of thedetection member 20. Therefore, it is possible to make them thinner and to prevent twisting which tends to occur at the free end side of theplate spring 22. In addition, since theplate spring 22 can be held by thefitting member 23, and these can be easily mounted to theholder 21, the assembly operation can be easily carried out. - A driving gear36 (that is, a second gear) is secured to the rotary shaft 30 (that is, a second rotary shaft) so as to be rotatable with the
rotary shaft 30. Ahelical gear 36A having the same module as thehelical gear 13A formed along the outer peripheral surface of therotary member 13 is formed along the outer peripheral surface of thedriving gear 36. Thescrew shaft 30 a which has a helical shape is formed from the portion of therotary shaft 30 adjacent to thedriving gear 36 to the left end of therotary shaft 30. The pitch between thread grooves of thescrew shaft 30 a is the same as the pitch of the internal threads formed in the inside surfaces 23 c and 23 c of the correspondingfitting portions - When both ends of the
rotary shaft 30 are supported between the supportingportion 17 a 1 of thesupport 17 a and the supportingportion 17b 1 of thesupport 17 b, thescrew shaft 30 a is set so as to be positioned directly above thefitting member 23 provided at the free end of theplate spring 22. Therefore, thefitting portions fitting member 23 provided at the free end of theplate spring 22 can engage thescrew shaft 30 a from the illustrated Z1 direction. - Here, since the
plate spring 22 is twisted less frequently as mentioned above, thefitting member 23 can be biased horizontally in the Z1 direction. Therefore, it is possible to prevent the production of tilted biasing force with respect to thescrew shaft 30 a, at both ends of thefitting portions screw shaft 30 a can be resiliently pressed against thefitting portions screw shaft 30 a and the inside surfaces 23 c and 23 c of the correspondingfitting portions - The biasing force of the
plate spring 22 pushes thefitting member 23 onto thescrew shaft 30 a, and theholder 21 towards thesecond base 17 e (that is, in the illustrated Z2 direction). Here, when thefitting member 23 is set so as to be positioned at about the center of the region between the tworails 17e e 2, the load of theholder 21 which holds the second magnet M2 is substantially uniformly distributed onto the tworails 17e e 2 through each of thesliders 21 a. This makes it possible to prevent the occurrence of problems such as tilting of theholder 21 and derailment of thesliders 21 a from therails 17e e 2. Therefore, it is possible to always move thedetection member 20 and the second magnet M2 parallel to the Hall element H2, making it possible to stably detect very small angles of rotation of the first rotary shaft (that is, the steering wheel) which is a detect shaft to be detected. - A fat axially extending
portion 36 a and a thinaxially extending portion 36 b which extend along the axial center portion of thedriving gear 36 in the X1 direction are formed at the illustrated right end side of thedriving gear 36. The thin axially extendingportion 36 b is formed continuously with the fat axially extendingportion 36 a in the illustrated X1 direction. An auxiliary gear (that is, a third gear) 40 is rotatably inserted onto the fat axially extendingportion 36 a. A biasingmember 50A is provided between the right end surface of thedriving gear 36 and theauxiliary gear 40. The biasingmember 50A used in the embodiment shown in FIGS. 1 and 2 is, for example, a torsion spring 50. Oneend 50 a of the biasingmember 50A is formed so as to extend in the illustrated X2 direction, and is inserted into aninsertion hole 36 c formed in thedriving gear 36 as shown in FIG. 3. Theother end 50 b of the biasingmember 50A is caught by a catchingportion 40 a formed in an opposing surface of theauxiliary gear 40. It is mounted in a twisted state so as to have a small inside diameter. In addition, it is subjected to a force sufficient to cause rotation of therotary shaft 30. Further, it is mounted in a flexed state in the axial direction. - A
helical gear 40A is formed along the outer peripheral surface of theauxiliary gear 40. More specifically, the outside diameter of the side of theauxiliary gear 40 opposing thedriving gear 36 is smaller than the outside diameter of the opposite side of theauxiliary gear 40. The portion between these sides of thegear 40A is a helical gear-shaped portion having an inverted spherical surface having a diametrical curvature equal to that of thehelical gear 13A formed at the outer peripheral surface of therotary member 13. In other words, as shown in FIG. 1, the teeth of theauxiliary gear 40 in axial cross section are helical along a circumferential direction of therotary member 13. Therefore, theauxiliary gear 40 is formed so that it reliably engages the gear of therotary member 13 at a location situated away from an imaginary normal line O-O′ in the illustrated X1 direction (see FIG. 3). Theauxiliary gear 40 may be a bevel gear in which the teeth thereof in axial cross section are linearly tilted along the circumferential direction of therotary member 13. - An
annular washer 55 and a first magnet M1 are provided at the illustrated right end side of theauxiliary gear 40. The inside diameter of the first magnet M1 is substantially equal to the outside diameter of the thin axially extendingportion 36 b of thedriving gear 36. The first magnet M1 can be secured to therotary shaft 30 by fitting the first magnet M1 onto the thin axially extendingportion 36 b. - Both surfaces of the
washer 55 are smooth surfaces having a small coefficient of friction. Sliding friction between an end surface of theauxiliary gear 40 and an end surface of the first magnet M1 can be reduced by interposing thewasher 55 between theauxiliary gear 40 and the first magnet M1. In order to prevent theauxiliary gear 40 and the first magnet M1 from becoming dislodged, it is preferable that aspeed nut 56 be provided so as to contact the end surface of the first magnet M1 and the end surface of thedriving gear 36. - The
rotary shaft 30 having the drivinggear 36, theauxiliary gear 40, the biasingmember 50A, thewasher 55, and the magnet M1 formed thereat is supported between the supportingportion 17 a 1 of thesupport 17 a and the supportingportion 17b 1 of thesupport 17 b. Here,bearings rotary shaft 30, respectively. Thebearings cylindrical bearing portion 61 and aflange 62 formed on one surface of the corresponding bearingportion 61. While both ends of therotary shaft 30 are inserted in thebearings portions portion 17 a 1 of thesupport 17 a and the supportingportion 17b 1 of thesupport 17 b, respectively. - This prevents shifting of the
rotary shaft 30 in the radial direction (that is, the direction perpendicular to the rotary shaft 30). - As shown in FIGS.1, when the
rotary shaft 30 is secured inside theunit case 17, the magnet M1 is set opposing the inclined surfaces of the substantially V-shaped portion of thefirst base 17 d. Thefitting portions fitting member 23 engage thescrew shaft 30 a. Thedriving gear 36 is disposed between thefirst base 17 d and the slidingsecond base 17 e. - As described above, the
unit case 17 having therotary shaft 30 and the like mounted thereat is secured at the bottom portion of the inside of thecase 12. When therotary member 13 is provided in thecase 12, thehelical gear 13A of therotary member 13 and thehelical gear 36A of thedriving gear 36 engage each other in a screw gear relationship. - Here, as shown in FIG. 3, the center of the
driving gear 36 is set so as to be situated at an intersection point Q where a perpendicular line (that is, the imaginary normal line O-O′) extending downward towards the rotary shaft 30 (that is, the second rotary shaft) from the center O of the rotary member 13 (that is, from the center axis of the steering wheel or first rotary shaft) and the rotational center axis of therotary shaft 30 intersect each other. The auxiliary gear (that is, the third gear) 40 is set at a location situated away from the intersection point Q in the illustrated X1 direction. - The outer peripheral surface of the
auxiliary gear 40 comprises thehelical gear 40A having an inverted spherical shape, so that, as shown in FIG. 1 and FIG. 3, the curved sectional shape lies along the pitch circle of therotary member 13. Therefore, even at a location situated away from the intersection point. Q in the illustrated X1 direction, it is possible to engage the inverted spherical,helical gear 40A of theauxiliary gear 40 and thehelical gear 13A of therotary member 13. It is preferable that the crests of the teeth of the inverted spherical,helical gear 40A and thehelical gears - A description will now be given of the operation which prevents backlash from occurring between the driving
gear 36A and thehelical gear 13A. - Since the
driving gear 36 is firmly fitted to therotary shaft 30, it cannot move in the axial direction. Theauxiliary gear 40 is inserted onto therotary shaft 30 through thedriving gear 36 so as to be relatively rotatably held through therotary shaft 30. The axial movement of theauxiliary gear 40 is restricted by the washer 50, the first magnet M1, and thespeed nut 56. The biasingmember 50A provided between the drivinggear 36 and theauxiliary gear 40 applies biasing force to thedriving gear 36 in the β2 direction, and biasing force to theauxiliary gear 40 in the β1 direction. Therefore, as shown in FIG. 4, a tooth surface 40A1 of thehelical gear 40A of theauxiliary gear 40 contacts a tooth surface 13A1 of thehelical gear 13A of therotary member 13 from the β1 direction. During this time, theauxiliary gear 40 is positioned as a result of being resiliently pressed by the biasingmember 50A in the axial direction (that is, the X2 direction). Therefore, even if the helical gears, that is, tapered surfaces contact each other, sliding between both tooth surfaces does not occur, so that both of the helical gears are stably in close contact with each other. - Here, with reference to the portion where the
helical gear 13A and thehelical gear 40A contact each other, a biasing force (that is, a rotational force) is exerted onto thedriving gear 36 in the β2 direction. Since, as mentioned above, theauxiliary gear 40 and therotary shaft 30 rotate relative to each other, thedriving gear 36 provided at therotary shaft 30 is rotated until a tooth surface 36A1 of thehelical gear 36A comes into contact with a tooth surface 13A2 of thehelical gear 13A of therotary gear 13. Even here, thedriving gear 36 is similarly positioned in the axial direction (that is, the X2 direction), so that axial sliding between the teeth of the helical gears does not occur, whereby they stably resiliently press against each other. - More specifically, the biasing
member 50A exerts rotational forces acting in opposite directions onto thedriving gear 36 and theauxiliary gear 40. Here, the tooth surface 36A1 of thehelical gear 36A of the drivingmember 36 and the tooth surface 40A1 of thehelical gear 40A of theauxiliary gear 40 resiliently sandwich both tooth surfaces 13A1 and 13A2 of thehelical gear 13A of therotary member 13 from both directions (that is, the β1 and β2 directions). Therefore, no gaps are created between thehelical gear 13A of therotary member 13 and thehelical gear 36A of thedriving gear 36, and between thehelical gear 13A of therotary member 13 and thehelical gear 40A of theauxiliary gear 40, so that they can always be kept in contact with each other. - Consequently, rattling resulting from backlash between the
rotary member 13 and thedriving gear 36 can be reduced, so that the rotational force exerted onto therotary member 13 from the steering wheel Sh can be efficiently transmitted to thedriving gear 36. - In addition, the
screw shaft 30 a engages thefitting portions fitting member 23. Here, thefitting portions screw shaft 30 a in the Z1 direction by the biasing force of theplate spring 22, so that backlash between thescrew shaft 30 a and the inside surfaces 23 c and 23 c of the correspondingfitting portions - When the
angle sensor 10 is mounted to the steering wheel Sh of an automobile, and the steering wheel Sh is rotated, therotary member 13 rotates in correspondence with this rotation. For example, when therotary member 13 is rotated once in the illustrated clockwise direction (that is, in the α1 direction), a rotational force in the illustrated β2 direction acts on theauxiliary gear 40 and thedriving gear 36 engaging therotary member 13, so that therotary shaft 30 and the first magnet M1 are set so as to rotate eight times in the illustrated β2 direction. - The outer peripheral surface of the first magnet M1 is magnetized so that the N pole and the S pole pass by the Hall elements H1 once or twice each time the first magnet M1 rotates once. Accordingly, the pair of Hall elements H1 provided at the V-shaped
first base 17 d opposing the first magnet M1 detect changes in the strength of the magnetic field of the magnet M1, making it possible to detect the rotational direction and very small rotational angles of therotary member 13. - When the
rotary shaft 30 is rotated in either the β1 direction or the β2 direction, thescrew shaft 30 a of therotary shaft 30 causes an advancing force in either the illustrated X1 direction or X2 direction (that is, in either one of the thrust directions) to act on thefitting portions holder 21. This causes thesliders 21 a of theholder 21 to slide on therails 17e e 2 of thesecond base 17 e and to move linearly in either the illustrated X1 direction or X2 direction. In other words, thescrew shaft 30 a of therotary shaft 30 and thefitting portions fitting member 23 are converting portions for converting the rotational movement of therotary shaft 30 in either the β1 or the β2 direction into linear movement. The converting portions cause thedetection member 20 to move in either the X1 or X2 direction in order to output a signal which varies linearly within the entire rotational angle range of the steering wheel Sh. - Here, as described above, the
plate spring 22 biases thefitting member 23 horizontally in order to prevent rattling between thescrew shaft 30 a of therotary shaft 30 and the inside surfaces 23 c and 23 c of the correspondingfitting portions detection member 20 which moves in accordance with the rotation of thescrew shaft 30 a advances with higher precision. In other words, the linearity between the angle of rotation of therotary member 13 and the distance of movement of thedetection member 20 can be enhanced. Therefore, when the second magnet M2 provided at thedetection member 20 moves while opposing the Hall element H2 in order to detect through the Hall element H2 any changes in the Z-direction component of the magnetic field generated by the second magnet M2 at this time, the rough angle of rotation of therotary member 13 can be detected with high precision. In other words, the Hall element H2 can generate an output which precisely corresponds to (or is proportional to) the angle of rotation of therotary member 13. - Even if the forms of the internal threads of the inside surfaces23 c and 23 c of the corresponding
fitting portions fitting member 23 is always biased towards thescrew shaft 30 a through theplate spring 22, so that rattling can be prevented from occurring for a long period of time, as a result of which the precision with which thedetection member 20 is advanced can be kept high. - The
fitting portions screw shaft 30 a and thefitting portions - FIG. 7 is a sectional view of the main portion of another embodiment of an angle sensor.
- In the angle sensor shown in FIG. 7, a biasing
member 50B is provided between anauxiliary gear 40 and awasher 55 instead of providing the biasingmember 50A between the drivinggear 36 and theauxiliary gear 40 as in the first embodiment. Arotary member 13 and adriving gear 36 include ahelical gear 13A and ahelical gear 36A, respectively, and anauxiliary gear 40 comprises a screw-cap-shapedgear 40A. Therotary member 13 and thedriving gear 36, and therotary member 13 and theauxiliary gear 40 engage each other in a, screw gear relationship. The rotations of theauxiliary gear 40 in the β1 and β2 directions (see FIG. 2:) are restricted, so that movements in only the X1 and X2 directions are possible. - The biasing
member 50B is, for example, a coil spring or a plate spring, and biases theauxiliary gear 40 towards the driving gear 36 (that is, in the illustrated X2 direction). A tapered or inverted spherical,helical gear 40A is provided at the outer peripheral surface of theauxiliary gear 40 similarly to the above, so that, when it is biased towards the drivinggear 36, thehelical gear 40A of theauxiliary gear 40 can engage thehelical gear 13A of therotary member 13. - The
helical gear 40A while rotating therotary member 30 moves along a tapered surface of thehelical gear 13A in the axial direction (that is, the X2 direction) so that gaps are not produced at the portion where thehelical gear 40A of theauxiliary gear 40 and thehelical gear 13A of therotary member 13 contact each other and at the portion where thehelical gear 13A and thehelical gear 36A of thedriving gear 36 contact each other. Therefore, one surface of thehelical gear 13A of therotary member 13 and one surface of thehelical gear 36A of thedriving gear 36 are always kept in contact with each other, making it possible to prevent rattling caused by backlash therebetween. - As in the first embodiment, the rotational force of the
rotary member 13 can be efficiently transmitted to thedriving gear 36, so that the linearity of theholder 21 can be increased, making it possible to detect the angle of rotation of the steering wheel Sh with high precision. - Although in the above-described embodiment a gap is prevented from being formed at the portion where the
helical gear 13A of therotary member 13 and thehelical gear 36A of thedriving gear 36 contact each other by incorporating a biasingmember 50A so that it is flexed in the inside diameter direction and axial direction, this may be achieved by incorporating the biasingmember 50A so that it is flexed in either the axial direction or the inside diameter direction. In addition, the biasingmember 50A may be incorporated so as to spread in the axial direction. - In the case where the biasing
member 50A is only flexed in the axial direction, it is preferable that the biasingmember 50A not be positioned in the direction of rotation with respect to at least one of theauxiliary gear 40 and thedriving gear 36. In this case, a tooth surface of thedriving gear 36 and a tooth surface of theauxiliary gear 40 slide along the tooth surfaces of thehelical gear 13A, as a result of which theauxiliary gear 40 and thedriving gear 36 rotate. Thus, it is possible to expect this embodiment to provide advantages similar to those provided by the first embodiment. - In the case where the biasing
member 50A is only flexed in the inside diameter direction, it is preferable that the biasingmember 50A not be positioned in the axial direction with respect to at least one of theauxiliary gear 40 and thedriving gear 36. In this case, a tooth surface of thedriving gear 36 and a tooth surface of theauxiliary gear 40 slide along the tooth surfaces of thehelical gear 13A, as a result of which theauxiliary gear 40 moves axially so that its location is fixed. Thus, it is possible to expect this embodiment to provide advantages similar to those provided by the first embodiment. - In the case where the biasing
member 50A is incorporated so as to spread in the axial direction, the axial location of theauxiliary gear 40 is restricted by thedriving gear 36. In addition, a tooth surface 40A2 of thehelical gear 40A and a tooth surface 13A2 of thehelical gear 13A are always in contact with each other, and a tooth surface 36A2 of thehelical gear 36A and a tooth surface 13A1 of thegear 13A are always in contact with each other. - In the above-described embodiment, the biasing
member 50A is incorporated so as to be flexed in both the inside diameter direction and the axial direction, and theauxiliary gear 40 is rotatably held with respect to therotary shaft 30. In addition, the axial movement of theauxiliary gear 40 is prescribed, and, with the location where theauxiliary gear 40 and therotary member 13 contact each other serving as a reference, thedriving gear 36 is biased towards therotary member 13. However, theauxiliary gear 40 may be joined to therotary shaft 30 through splines, and the axial movement of theauxiliary gear 40 may be such as not to be restricted. Here, it is preferable that the biasingmember 50A not be positioned in the direction of rotation with respect to at least one of theauxiliary gear 40 and thedriving gear 36. - In this case, the
helical gear 40A while rotating therotary shaft 30 moves axially along a tapered surface of thehelical gear 13A so that no gaps are created at the portion where thehelical gear 13A and thehelical gear 40A of theauxiliary gear 40 contact each other and at the portion where thehelical gear 13A and thehelical gear 36A of thedriving gear 36 contact each other. Therefore, a tooth surface of thehelical gear 13A of therotary member 13 and a tooth surface of thehelical gear 36A of thedriving gear 36 are always in contact with each other, so that rattling caused by backlash therebetween does not occur. - Although in the first embodiment the biasing
member 50A is provided between the drivinggear 36 and theauxiliary gear 40, a biasing member may be disposed between theauxiliary gear 40 and thewasher 55 as a result of holding thewasher 55 and thedriving gear 36 so that they rotate integrally. - Although in the each of the above-described embodiments the degree with which the
fitting portions fitting member 23 and the thread grooves of thescrew shaft 30 a contact each other at the contact portions is increased by forming thefitting portions fitting member 23, thefitting portions fitting member 23. - Although in each of the above-described embodiments the
plate spring 22 and theholder 21, and theplate spring 22 and thefitting member 23 are joined together through cuts and protrusions at two locations, they may be joined together at at least two or more locations or by bonding the whole surfaces thereof. - Although as guiding members for guiding the
detection member 20 tworails 17e e 2 are provided on thesecond base 17 e, one rail or three or more rails may be used as long as thedetection member 20 can be moved linearly in the direction of movement. - Although, in each of the embodiments, the
cuts protrusions cuts protrusions plate spring 22 may be held by theholder 21 by insert molding. In other words, mounting structures other than that described above may be used as long as theplate spring 22 is positioned and held by theholder 21 without any rattling of theplate spring 22 with respect to theholder 21. - Although, in each of the embodiments, the
cutaway portion 22C is square, it may have a shape which separates the portion between thecuts holes surfaces plate spring 22 are flat surfaces, ribs may be formed thereon along the axial direction, or ends thereof may be bent at bending lines parallel to the axial line in order to increase the twisting strength without affecting the flexed portion of theplate spring 22. - According to the present invention described in detail above, backlash between the rotary member and the driving gear can be reduced by the auxiliary gear, making it possible to efficiently transmit the rotational force of the rotary member to the driving gear. Therefore, the linearity of the angle sensor can be increased, making it possible to detect the angle of rotation with high precision.
- As can be understood from the foregoing description, according to the present invention, the degree with which the screw shaft and the fitting portions contact each other can be increased, making it possible to decrease rattling which tends to occur therebetween. Therefore, the detection member can be advanced in the axial direction thereof with higher precision, making it possible to detect the angle of rotation of the first: rotary shaft with high precision.
Claims (11)
1. An angle sensor for detecting an angle of rotation of a first rotary shaft by a detecting operation of a detecting portion, the angle sensor comprising a first gear which rotates in accordance with the first rotary shaft, a second rotary shaft which extends in a direction perpendicular to the first rotary shaft; a second gear which rotates along with the second rotary shaft and which engages the first gear; a third gear which is rotatably provided at the second rotary shaft and which engages the first gear; and the detecting portion which detects the rotation of the second rotary shaft;
wherein the first gear engages the second gear and the third gear in a screw gear relationship, and wherein a biasing member is provided at the second rotary shaft, the biasing member causing a tooth of the first gear to be sandwiched between a tooth of the second gear and a tooth of the third gear.
2. An angle sensor according to , wherein the biasing member exerts a biasing force onto the second gear in a direction of rotation thereof.
claim 1
3. An angle sensor according to , wherein the biasing member exerts a biasing force in a direction in which the second gear approaches the first gear.
claim 1
4. An angle sensor according to , wherein the first gear and the second gear engage each other at an intersection point where an imaginary normal line from the center of rotation of the first gear vertically intersects the second rotary shaft, and wherein the third gear is provided at a location situated away from the intersection point.
claim 1
5. An angle sensor according to , wherein the third gear is a helical gear having an inverted spherical surface.
claim 4
6. An angle sensor for detecting an angle of rotation of a first rotary shaft as a result of a detecting operation by a detecting member, the angle sensor comprising a first gear which rotates in accordance with the first rotary shaft, a screw shaft which extends in a direction perpendicular to the first rotary shaft, a second gear which rotates with the screw shaft and which engages the first gear, a fitting member which engages the screw shaft and which moves in an axial direction of the screw shaft by a rotational force of the screw shaft, a detection member to be detected which moves along with the fitting member, a detection portion to be detected provided at the detection member, and a detecting member for detecting a linear movement of the detection portion,
wherein the fitting member and the detection member are connected together by a plate spring, wherein the fitting member is supported by the plate spring, wherein a plate thickness direction of the plate spring is oriented in a direction perpendicular to a direction of movement of the fitting member and the detection member, and wherein the plate spring is secured to the fitting member and the detection member in the direction perpendicular to the direction of movement of the fitting member and the detection member and at a location where a gap is formed in a plate surface direction, the plate spring being secured along a line facing the direction of movement of the fitting member and the detection member.
7. An angle sensor according to , wherein a mounting surface of the plate spring for mounting to the fitting member and a mounting surface of the plate spring for mounting to the detection member are located in the same plane.
claim 6
8. An angle sensor according to , wherein the fitting member comprises a U-shaped fitting portion which opens in a direction perpendicular to a plane of the plate spring, the fitting portion engaging the screw shaft.
claim 6
9. An angle sensor according to , wherein the fitting member comprises a pair of the fitting portions which are separated from each other in the direction of movement thereof, wherein the plate spring has a cutaway portion formed in the center portion thereof, and wherein the pair of fitting portions are biased towards the screw shaft by an area of the plate spring where the cutaway portion is not formed.
claim 8
10. An angle sensor according to , further comprising a guiding member for guiding the movement of the detection member in an axial direction thereof, the guiding member having at least one rail which is provided parallel to the screw shaft, the detection member sliding on the at least one rail.
claim 6
11. An angle sensor according to , wherein two of the rails parallel to each other are provided along the direction of movement, and wherein the fitting member is located substantially at the center of a region between the two rails.
claim 10
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP34876699A JP2001165698A (en) | 1999-12-08 | 1999-12-08 | Angle sensor |
JP11-348792 | 1999-12-08 | ||
JP11-348766 | 1999-12-08 | ||
JP34879299A JP3597743B2 (en) | 1999-12-08 | 1999-12-08 | Detector feeder |
Publications (2)
Publication Number | Publication Date |
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US20010003435A1 true US20010003435A1 (en) | 2001-06-14 |
US6396386B2 US6396386B2 (en) | 2002-05-28 |
Family
ID=26578821
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/729,614 Expired - Fee Related US6396386B2 (en) | 1999-12-08 | 2000-12-04 | Angle sensor which makes it possible to prevent rattling caused by backlash between gears inside the angle sensor |
Country Status (3)
Country | Link |
---|---|
US (1) | US6396386B2 (en) |
EP (1) | EP1114765B1 (en) |
DE (1) | DE60030533T2 (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060170415A1 (en) * | 2003-06-30 | 2006-08-03 | Martin Budaker | Device for recording a rotational movement in a vehicle steering system |
DE102006024680A1 (en) * | 2006-05-26 | 2007-11-29 | Leopold Kostal Gmbh & Co. Kg | Gear shift lever position measuring device, has magnet or magnet holder supported at contact surface, and spring units e.g. flexible tongue, pressing magnet or holder against contact surface |
EP1895284A2 (en) | 2006-08-28 | 2008-03-05 | Alps Electric Co., Ltd. | Torque sensor |
US20080148883A1 (en) * | 2005-02-23 | 2008-06-26 | Interpump Hydraulics S.P.A. | Power Take-Off for Industrial Vehicles |
CN102414539A (en) * | 2009-04-24 | 2012-04-11 | 利奥波德·科世达责任有限股份公司 | Angle sensor |
US20130212893A1 (en) * | 2010-08-24 | 2013-08-22 | Thomas Richard Stafford | Apparatus Adapted To Provide An Indication Of An Angular Position Of An Input Member Over Multiple Turns |
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WO2024238326A1 (en) * | 2023-05-12 | 2024-11-21 | Schaeffler Technologies AG & Co. KG | Position sensor |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100539027B1 (en) * | 2002-10-18 | 2005-12-26 | 현대모비스 주식회사 | detection apparatus for steering angle in vehicle |
WO2009025937A1 (en) * | 2007-08-22 | 2009-02-26 | Kostal Of America | Steering angle sensor |
CN205484398U (en) * | 2015-12-25 | 2016-08-17 | 罗伯特·博世有限公司 | Sensing device , sensing system and a steering system |
CN107525485B (en) * | 2017-08-08 | 2020-05-29 | 重庆清平机械有限责任公司 | Inner helical gear bar spacing measuring method |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3050704A (en) | 1959-05-04 | 1962-08-21 | Allen Bradley Co | Rectilinear variable resistor |
US3400355A (en) * | 1966-12-02 | 1968-09-03 | Cts Corp | Variable resistance control with improved heat dissipator arrangement and bearing means |
NL143720B (en) | 1970-10-20 | 1974-10-15 | Philips Nv | POTENTIOMETER WITH CONVEYOR SCREW. |
US3660796A (en) * | 1971-01-21 | 1972-05-02 | Weston Instruments Inc | Resistor with at least two points of manipulation for adjustment |
US4075597A (en) * | 1976-12-20 | 1978-02-21 | Beckman Instruments, Inc. | Variable resistor with dual ratio input shaft |
US4313349A (en) * | 1980-01-02 | 1982-02-02 | General Electric Company | Sealed electrical control device for x-ray apparatus |
US4712101A (en) * | 1984-12-04 | 1987-12-08 | Cheetah Control, Inc. | Control mechanism for electronic apparatus |
JPS6227877A (en) | 1985-07-30 | 1987-02-05 | Toshiba Corp | Optical character reader |
JPH03290059A (en) * | 1990-02-22 | 1991-12-19 | Mitsubishi Electric Corp | Electric distributor for ignition of internal combustion engine |
JP2959295B2 (en) * | 1992-09-22 | 1999-10-06 | 松下電器産業株式会社 | Motor driven variable resistor |
JPH06109103A (en) * | 1992-09-24 | 1994-04-19 | Hitachi Ltd | Engine ignition system drive mechanism |
DE19506938A1 (en) | 1995-02-28 | 1996-08-29 | Bosch Gmbh Robert | Method and device for measuring the angle of a rotatable body |
GB2316921A (en) * | 1996-09-05 | 1998-03-11 | Rover Group | A steering angle indicator for a motor vehicle |
JPH11211456A (en) * | 1998-01-22 | 1999-08-06 | Alps Electric Co Ltd | Rotating angle detecting device |
-
2000
- 2000-11-20 DE DE60030533T patent/DE60030533T2/en not_active Expired - Fee Related
- 2000-11-20 EP EP00310301A patent/EP1114765B1/en not_active Expired - Lifetime
- 2000-12-04 US US09/729,614 patent/US6396386B2/en not_active Expired - Fee Related
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US20060170415A1 (en) * | 2003-06-30 | 2006-08-03 | Martin Budaker | Device for recording a rotational movement in a vehicle steering system |
US20080148883A1 (en) * | 2005-02-23 | 2008-06-26 | Interpump Hydraulics S.P.A. | Power Take-Off for Industrial Vehicles |
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US20130212893A1 (en) * | 2010-08-24 | 2013-08-22 | Thomas Richard Stafford | Apparatus Adapted To Provide An Indication Of An Angular Position Of An Input Member Over Multiple Turns |
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US9254868B2 (en) | 2013-05-29 | 2016-02-09 | Aisin Seiki Kabushiki Kaisha | Displacement detection apparatus for linear motion mechanism and rear wheel steering apparatus for vehicle including the same |
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CN110319782A (en) * | 2018-03-30 | 2019-10-11 | 中强光电股份有限公司 | Projection arrangement, backlash detection system and its method |
US11300867B2 (en) | 2018-03-30 | 2022-04-12 | Coretronic Corporation | Projection apparatus, backlash detecting system and method thereof |
CN111223706A (en) * | 2018-11-27 | 2020-06-02 | 法雷奥日本株式会社 | Switch device and assembling method thereof |
CN110849259A (en) * | 2019-12-19 | 2020-02-28 | 杭州人人集团有限公司 | Steering wheel angle sensor for vehicle |
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WO2024238326A1 (en) * | 2023-05-12 | 2024-11-21 | Schaeffler Technologies AG & Co. KG | Position sensor |
Also Published As
Publication number | Publication date |
---|---|
EP1114765A3 (en) | 2003-01-22 |
DE60030533D1 (en) | 2006-10-19 |
EP1114765B1 (en) | 2006-09-06 |
EP1114765A2 (en) | 2001-07-11 |
DE60030533T2 (en) | 2007-05-10 |
US6396386B2 (en) | 2002-05-28 |
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