JP5463684B2 - Damping force adjustable shock absorber - Google Patents

Description

  The present invention relates to a damping force adjusting type shock absorber mounted on a suspension device of a vehicle such as an automobile.

  In general, a damping force adjusting type shock absorber mounted on a suspension device of an automobile slidably fits a piston having a piston rod connected to a cylinder filled with oil and slidably defines the inside of the cylinder in two chambers. The flow of oil generated by the sliding of the piston in the cylinder is controlled by a damping force generation mechanism consisting of an orifice, a disk valve, etc. to generate a damping force, and is also attenuated using a flow control valve, a pressure control valve, etc. The damping force is adjusted by changing the flow resistance of the force generation mechanism.

  In this type of damping force adjusting type shock absorber, as described in Patent Document 1, for example, a back pressure chamber is formed at the back of a disc valve which is a damping force generating mechanism, and this back pressure chamber is fixed to a fixed orifice. There are some which are connected to the upstream cylinder chamber via a pressure control valve (solenoid valve) and connected to the downstream cylinder chamber via a pressure control valve (solenoid valve).

  With this configuration, the flow resistance of the oil liquid can be directly adjusted by the pressure control valve, and the opening pressure of the disk valve can be adjusted by adjusting the internal pressure of the back pressure chamber. The adjustment range can be widened.

However, the damping force adjustment type shock absorber described in Patent Document 1 has the following problems.
Since the area of the valve body of the pressure control valve is the pressure receiving area and the internal pressure of the back pressure chamber is adjusted, there is a problem that the solenoid becomes large when the valve opening pressure is increased to increase the damping force on the hardware side.

JP 2001-12534 A

The present invention has been made in view of the above points, and reduces the pressure receiving area, increases the valve opening pressure of the pressure control valve without increasing the thrust of the large plunger, and increases the damping force on the hardware side. It is an object of the present invention to provide a damping force adjusting type shock absorber.

In order to solve the above-mentioned problems, the present invention provides a cylinder in which a fluid is sealed, a piston slidably fitted in the cylinder, one end connected to the piston, and the other end outside the cylinder. A damping force adjustment comprising: a piston rod extended to the inside of the cylinder; and a pressure control valve capable of adjusting a valve opening pressure by controlling a flow of fluid generated by sliding of the piston in the cylinder to generate a damping force. In the type shock absorber,
The pressure control valve includes a valve body seated on a seat surface, a shaft portion provided in the valve body and provided with a communication passage extending in an axial direction therein, and the shaft portion being inserted to remove the valve body from the seat surface. a plunger for adjusting the valve opening pressure to urge the side, a solenoid for adjusting the thrust of the plunger, provided on the rear surface of the shaft portion, which acts to urge the valve body to the seat surface A valve body back pressure chamber, and a main spring for biasing the plunger or the valve body to a side opposite to the biasing force of the plunger ,
A main valve that generates a damping force by controlling a flow of fluid generated by sliding of the piston in the cylinder; and a back pressure chamber that applies an internal pressure to the main valve in a valve closing direction. Is introduced into the back pressure chamber, and the internal pressure of the back pressure chamber is adjusted by the pressure control valve,
The pressure receiving area of the valve body is obtained by communicating the back pressure chamber and the valve body back pressure chamber through the communication passage of the shaft portion in a state where the valve body is seated on the seat surface. The pressure receiving area is obtained by subtracting the area on the valve body back pressure chamber side from the area on the surface side.

According to the damping force adjustment type shock absorber according to the present invention, since the pressure receiving area can be reduced, the opening pressure of the pressure control valve is increased without requiring a large plunger thrust, and the damping force on the hardware side is increased. Can be increased .

It is a longitudinal cross-sectional view which expands and shows the damping force generation mechanism of the damping force adjustment type hydraulic buffer which concerns on the reference technique of this invention. It is a front view which shows the valve spring of the pressure control valve of the damping force generation mechanism shown in FIG. It is a front view which shows the modification of the valve spring of the pressure control valve of the damping force generation mechanism shown in FIG. 1 is a longitudinal sectional view of a damping force adjusting hydraulic shock absorber according to a reference technique of the present invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the damping force generation mechanism of the damping force adjustment type hydraulic buffer which concerns on 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the other modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the further another modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the further another modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the further another modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the further another modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the seat surface and seat part of the pressure control valve of the damping force adjustment type hydraulic shock absorber according to each embodiment of the present invention. It is a graph which shows the damping force characteristic of the damping force adjustment type hydraulic buffer which concerns on each embodiment of this invention. It is a longitudinal cross-sectional view which expands and shows the part of the pressure control valve of the damping force generation mechanism of the damping force adjustment type hydraulic buffer which concerns on 2nd Embodiment of this invention.

Hereinafter, a reference technique of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 4, the damping force adjustment type hydraulic shock absorber 1 (damping force adjustment type shock absorber) according to the present technology has a double cylinder structure in which an outer cylinder 3 is provided outside the cylinder 2. A reservoir 4 is formed between 2 and the outer cylinder 3. A piston 5 is slidably fitted in the cylinder 2, and the inside of the cylinder 2 is defined by the piston 5 as two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 6 is connected to the piston 5 by a nut 7, and the other end side of the piston rod 6 passes through the cylinder upper chamber 2 </ b> A and is a rod guide attached to the upper ends of the cylinder 2 and the outer cylinder 3. 8 and an oil seal 9 are extended to the outside of the cylinder 2. A base valve 10 that partitions the cylinder lower chamber 2 </ b> B and the reservoir 4 is provided at the lower end of the cylinder 2.

  The piston 5 is provided with oil passages 11 and 12 for communicating between the cylinder upper and lower chambers 2A and 2B. The oil passage 11 is provided with a check valve 13 that allows only fluid to flow from the cylinder lower chamber 2B side to the cylinder upper chamber 2A side, and the oil passage 12 has a cylinder upper chamber 2A side. A disk valve 14 is provided that opens when the pressure of the oil liquid reaches a predetermined pressure and relieves it to the cylinder lower chamber 2B side.

  The base valve 10 is provided with oil passages 15 and 16 that allow the cylinder lower chamber 2 </ b> B and the reservoir 4 to communicate with each other. The oil passage 15 is provided with a check valve 17 that allows only fluid to flow from the reservoir 4 side to the cylinder lower chamber 2B side, and the oil passage 16 has oil in the cylinder lower chamber 2B side. A disk valve 18 is provided that opens when the liquid pressure reaches a predetermined pressure and relieves it to the reservoir 4 side. An oil liquid is sealed in the cylinder 2, and an oil liquid and a gas are sealed in the reservoir 4.

  A separator tube 20 is externally fitted to the cylinder 2 via seal members 19 at both upper and lower ends, and an annular oil passage 21 is formed between the cylinder 2 and the separator tube 20. The annular oil passage 21 is communicated with the cylinder upper chamber 2 </ b> A by an oil passage 22 provided on a side wall near the upper end portion of the cylinder 2. A small-diameter opening 23 is provided on the side wall of the separator tube 20, and a large-diameter opening 24 is provided substantially concentrically with the opening 23 on the side wall of the outer cylinder 3. A damping force generating mechanism 25 is attached to 24.

  The damping force generation mechanism 25 will be described with reference to FIGS. As shown in FIG. 1, one end of a cylindrical case 26 is inserted into the opening 24 and fixed by welding. A valve unit 30 in which a pilot type (back pressure type) main valve 27 and a pressure control valve 28 (solenoid valve) are integrated is inserted into the case 26, and is fixed by a nut 31.

  The valve unit 30 includes a solenoid case 32 that is fixed to the case 26 by a nut 31. A guide bore 33 is formed at the outer end of the solenoid case 32 along the axial direction. A plunger 34 is slidably guided in the guide bore 33, and further, a coil 35 (solenoid) and a plunger spring 36 (compression coil spring) as a main spring are accommodated, a core 37 is fitted, and a solenoid case is formed by caulking. By fixing to 32, the coil 35 is fixed and one end of the plunger spring 36 is supported. The coil 35 is connected to a lead wire 38 for energization and extends to the outside.

  A passage bore 39 concentric with the guide bore 33 is formed at the inner end of the solenoid case 32, and the guide bore 33 and the passage bore 39 communicate with each other via a small-diameter port 40. A bottomed cylindrical guide member 41 and a bottomed cylindrical valve member 42 are arranged in this order at the inner end of the solenoid case 32, and one end of a stepped cylindrical passage member 43 is connected to the valve member 42 and The guide member 41 is inserted into the bottom portion, and the tip end portion is screwed into the passage bore 39, and these are integrally coupled. A large-diameter portion 44 in the middle of the passage member 43 is fitted into the valve member 42, and a chamber 45 is formed inside the valve member 42. The other end portion of the passage member 43 is fitted into the opening 23 of the separator tube 20, and one end portion of the axial oil passage 46 inside the passage member 43 is communicated with the annular oil passage 21. A fixed orifice 47 (introduction orifice) is provided at an intermediate portion of the axial passage 46.

  A plurality of oil passages 49 are provided in the bottom portion of the valve member 42, and an annular valve seat 50 projects from the outer end surface of the bottom portion on the outer peripheral side of the oil passage 49. Between the valve member 42 and the guide member 41, the inner peripheral portion of a plurality of stacked disc valves 51 (main valve) is clamped, and the outer peripheral portion of the disc valve 51 is seated on the valve seat 50. An annular seal member 52 is fixed to the back surface of the disk valve 51, and the seal member 52 is fitted in a liquid-tight and slidable manner on the inner peripheral surface of the cylindrical portion of the guide member 41, so that the guide A back pressure chamber 53 is formed inside the member 41. Then, the disk valve 51 receives the pressure of the oil liquid in the oil passage 49 and bends and separates (opens) from the valve seat 50, and the chamber 45 in the valve member 42 is changed to the chamber 48 (outer cylinder) in the case 26. 3 is communicated with the reservoir 4 through the opening 24. The disc valve 51 and the back pressure chamber 53 form a pilot type (back pressure type) damping valve, and the internal pressure of the back pressure chamber 53 acts in the valve closing direction of the disc valve 51. The upstream side of the fixed orifice 47 in the axial oil passage 46 of the valve member 42 is communicated with the chamber 45 in the valve member 42 by an oil passage 54 provided in the passage member 43, and the downstream side of the fixed orifice 47 is The back pressure chamber 53 communicates with the radial oil passage 55.

  A valve body 56 that opens and closes the port 40 is supported at the distal end portion of the plunger 34 so as to be movable in the axial direction. The valve body 56 is elastically supported by a valve spring 57 (plate spring). The valve body 56 has a stepped shape including a large-diameter head portion 58 and a small-diameter shaft portion 59. The head portion 58 has an annular seat portion that is seated on the seat surface 60 at the peripheral portion of the port 40 in the guide bore 33. 61 protrudes. The shaft portion 59 is slidably inserted into a guide hole 62 that penetrates the central portion of the plunger 34.

  The head portion 58 of the valve body 56 is formed with a recess 80 having a diameter substantially the same as that of the port 40 so as to oppose the port 40 in the immediate vicinity of the inner peripheral portion of the annular seat portion 61. The width in the radial direction of the front end seated on the seat surface 60 is sufficiently small.

  As shown in FIG. 2, in the valve spring 57, a valve hole 63 </ b> A is provided in a substantially circular contact portion 63, and a leg portion 64 extends from the contact portion 63 in the diameter direction of the plunger 34. The valve body 56 has an annular shape in which the shaft portion 59 is inserted into the valve hole 63A, the head portion 58 contacts the contact portion 63, and the distal end portion of the leg portion 64 protrudes from the outer peripheral edge portion of the plunger 34. It abuts on the spring receiving portion 65 and is elastically supported by the plunger 34 so as to be movable in the axial direction. As shown in FIG. 3, a plurality of leg portions 64 of the valve spring 57 may be arranged radially (three at equal intervals in the illustrated example).

  The port 40 and the valve body 56 form a pressure control valve 28, and the valve body 56 opens when the pressure of the oil liquid in the port 40 reaches a predetermined pressure. Adjustment is made according to the spring force and the thrust of the solenoid, that is, the energization current to the coil 35. The guide bore 33 communicates with the chamber 48 through an oil passage 66 formed in the solenoid case 32. The plunger 34 is provided with a throttle passage 67 that allows the chambers formed at both ends thereof to communicate with each other, and an appropriate damping force is applied to the movement.

  The spring stiffness of the valve spring 57 is higher than that of the plunger spring 36, the mass of the valve body 56 is sufficiently smaller than the mass of the plunger 34, and the natural frequency of the valve body 56 is set sufficiently high. .

Next, the operation of the present technology configured as described above will be described.
The damping force adjusting hydraulic shock absorber 1 has a cylinder 2 side connected to a lower spring side, a piston rod 6 side connected to an upper spring side, and a lead wire 38 of a coil 35 connected to a suspension device of a vehicle such as an automobile. Connected to a controller (not shown).

  During the extension stroke of the piston rod 6, the check valve 13 of the piston 5 is closed by the movement of the piston 5 in the cylinder 2, and the oil liquid on the cylinder upper chamber 2 </ b> A side is pressurized before the disk valve 14 is opened. Then, the oil flows through the oil passage 22 and the annular oil passage 21 and flows from the opening 23 of the separator tube 20 to the axial oil passage 46 of the damping force generation mechanism 25. Before the disc valve 51 of the main valve 27 is opened, the oil flows through the fixed orifice 47, the passage bore 39 and the port 40, opens the valve body 56 of the pressure control valve 28, and flows to the guide bore 33. Furthermore, it flows to the reservoir 4 through the oil passage 66 and the chamber 48. When the pressure in the chamber 45 of the valve member 42 reaches the valve opening pressure of the disk valve 51, the disk valve 51 is opened, and the oil liquid flows from the upstream side of the fixed orifice 47 of the axial oil path 46 to the oil path. 54, flows through the oil chamber 45 and the oil passage 49 to the chamber 48.

  At this time, the oil corresponding to the movement of the piston 5 opens the check valve 17 of the base valve 10 from the reservoir 4 and flows into the cylinder lower chamber 2B. When the pressure in the cylinder upper chamber 2A reaches the valve opening pressure of the disk valve 14 of the piston 5, the disk valve 14 is opened, and the pressure in the cylinder upper chamber 2A is relieved to the cylinder lower chamber 2B. Prevent excessive pressure rise of 2A.

  During the contraction stroke of the piston rod 6, the check valve 13 of the piston 5 is opened by the movement of the piston 5 in the cylinder 2, the check valve 17 of the oil passage 15 of the base valve 10 is closed, and the disc valve 18 is opened. Before, the fluid in the piston lower chamber 2B flows into the cylinder upper chamber 2A, and the amount of fluid that has entered the cylinder 2 from the piston rod 6 passes from the cylinder upper chamber 2A through the same path as in the extension stroke. Flows through to the reservoir 4. When the pressure in the cylinder lower chamber 2B reaches the valve opening pressure of the disk valve 18 of the base valve 10, the disk valve 18 is opened, and the pressure in the cylinder lower chamber 2B is relieved to the reservoir 4, thereby Prevent excessive pressure rise of 2B.

  As a result, during the expansion / contraction stroke of the piston rod 6, before the main valve 27 is opened (piston speed low speed region), a damping force is generated by the fixed orifice 47 and the pressure control valve 28, and after the main valve 27 is opened. In the (piston speed high speed region), a damping force is generated according to the opening degree. The damping force can be directly controlled regardless of the piston speed by adjusting the valve opening pressure of the pressure control valve 28 by the energization current to the coil 35. At this time, since the internal pressure of the back pressure chamber 53 is adjusted by the valve opening pressure of the pressure control valve 28, the valve opening pressure of the main valve 27 can be adjusted simultaneously, thereby widening the adjustment range of the damping force characteristic. can do.

  At this time, in the pressure control valve 28, the spring stiffness of the valve spring 57 is set higher than the spring stiffness of the plunger spring 36, and the mass of the valve body 56 is sufficiently smaller than the mass of the plunger 34. Since the frequency is set sufficiently high, a response delay due to the inertia of the plunger 34 is unlikely to occur, and overshooting can be prevented and appropriate damping force control can be performed. When the pressure of the port 40 suddenly rises, the valve spring 57 is bent and only the lightweight valve body 56 is retracted and opened, and then the plunger 34 follows and retracts. Therefore, the pressure control valve Due to the valve opening delay of 28, the pressure in the back pressure chamber 53 does not rise excessively, and stable damping force control can be performed. Further, since the natural frequency of the valve body 56 is set sufficiently high, it is possible to prevent the generation of abnormal noise due to self-excited vibration and the instability of the damping force.

  Further, in the pressure control valve 28, by providing the annular seat portion 61 on the head portion 58 of the valve body 56, the flow passage area at the time of valve opening can be increased, and the adjustment range of the damping force on the soft side can be increased. Can be wide. On the other hand, when a needle valve is used as a pressure control valve, for example, as described in JP-A-7-259918, a large flow passage area cannot be obtained when the valve is opened. It is difficult to sufficiently reduce the damping force.

  Referring to FIG. 12, in the pressure control valve 28, the fluid force in the valve closing direction acts on the valve body 56 by the flow of the high-speed oil that flows out from the port 40 into the guide bore 33 when the valve is opened. . Due to this fluid force, the valve opening pressure of the valve body 56 increases and the damping force on the soft side increases, or the fluid force fluctuates depending on the piston speed and the opening of the valve body 56, thereby causing the pressure control valve 28. The damping force control due to the above becomes unstable, and the valve body 56 vibrates and chattering occurs. Therefore, for example, as described in JP-A-11-287281, when a disc valve is used as a pressure control valve, the influence of such a fluid force becomes a problem.

  On the other hand, by forming the recess 80 in the immediate vicinity of the inner peripheral portion of the annular seat portion 61, the pressure receiving area A at the front end portion of the seat portion 61 on which the fluid force acts can be sufficiently reduced. The influence can be reduced, the damping force on the soft side can be made sufficiently small, and the damping force control by the pressure control valve 28 can be stabilized. In this way, it is desirable to form the recess 80 in the immediate vicinity of the inner peripheral portion of the annular seat portion 61. However, for example, a disk valve is used even in the case of a gently tapered portion from the annular seat portion 61 toward the bottom surface of the recess 80. Rather than doing this, problems such as chattering can be reduced.

  FIG. 13 shows the damping force characteristics of the damping force adjusting hydraulic shock absorber 1. As shown in FIG. 13, the adjustment range R of the damping force characteristic from soft to hard of the damping force adjustment type hydraulic shock absorber is wider than the conventional adjustment range r.

In the above technique , the valve unit 30 in which the main valve 27 and the pressure control valve 28 are integrated is disposed in the case 26 on the side of the cylinder 2, and the oil liquid between the annular oil passage 21 and the reservoir 4 is disposed. Although the damping force is generated by controlling the flow of the valve, the valve unit 30 is disposed in the piston 5 or the base valve 10, and the damping force is generated by appropriately controlling the flow of the oil in the oil passage. You may do it.

Next, a first embodiment of the present invention will be described with reference to FIGS. In the following description, the same reference numerals are given to the same parts with respect to the above-described reference technique , and only different parts will be described in detail.

  FIG. 5 is an enlarged view of a portion of the pressure control valve 28 of the damping force generation mechanism 25 which is a main part of the present embodiment. As shown in FIG. 5, in this embodiment, the diameter of the port 40 forming the pressure control valve 28, the head portion 58 of the valve body 56, the shaft portion 59, and the seat portion 61 is larger than that of the first embodiment. It is getting bigger. Further, a valve body communication passage 70 is passed through the valve body 56 along the axial direction thereof. A tubular guide pin 71 is press-fitted and fixed to the rear end portion of the guide hole 62 of the plunger 34 and protrudes to the rear portion of the plunger 34. A communication path 72 passes through the guide pin 71 along the axial direction thereof. A guide hole 73 is provided in the core 37 so as to face the guide pin 71. The guide pin 71 is slidably and liquid-tightly inserted into the guide hole 73, and the valve body back pressure chamber 74 is inserted into the guide hole 73. Is formed.

  When the pressure control valve 28 is closed, that is, when the seat portion 61 of the valve body 56 is seated on the seat surface 60, the valve body back pressure chamber 74 is connected to the communication path 72 of the guide pin 71 and the guide of the plunger 34. It communicates with the port 40 through the hole 62 and the valve body communication passage 70 of the valve body 56. Therefore, the pressure receiving area of the valve body 56 with respect to the port 40 is an area obtained by subtracting the cross-sectional area of the shaft portion 59 from the area inside the seat 61.

  Thereby, since the valve body 56 can adjust the pressure receiving area with respect to the port 40 not only by the diameter of the seat portion 61 but also by the diameter of the shaft portion 59, the degree of freedom in setting the valve opening characteristics of the pressure control valve 28, As a result, the degree of freedom in setting the damping force characteristic of the damping force generation mechanism 25 can be increased.

  For example, even when the diameter of the port 40 is increased and the damping force on the soft side when the valve body 56 is opened is set to be sufficiently small, by increasing the diameter of the shaft portion 59, Since the pressure receiving area can be reduced, the opening pressure of the pressure control valve 28 can be increased and the hard-side damping force can be increased without requiring a large thrust force of the plunger 34.

  Further, in the present embodiment, as shown in FIG. 12, the valve body 58 of the pressure control valve 28 has the side wall 80A of the concave portion 80 of the inner peripheral portion of the seat portion 61 substantially perpendicular to the seat surface 61, Is formed in a tapered shape so that the pressure receiving area A at the front end portion of the seat portion 61 is sufficiently small and the fluid force acts against the fluid force caused by the flow of the oil liquid flowing out from the port 40 into the guide bore 33. Since the shape is difficult, the influence of the fluid force can be effectively reduced, the soft-side damping force can be made sufficiently small, and the damping force control by the pressure control valve 28 can be stabilized.

Next, a modification of the first embodiment will be described with reference to FIGS.
In the modification shown in FIG. 6, the guide pin 71 is integrally formed with the plunger 34 in the first embodiment. Thereby, the number of parts can be reduced.

  In the modification shown in FIG. 7, in the second embodiment, the bottomed cylindrical guide member 75 having the guide hole 73 provided separately from the core 37 is provided in the core 37 (solenoid case). It is inserted into the hole 76. The guide member 75 is fixed in the axial direction with the bottom thereof being in contact with the bottom of the mounting hole 76. As a result, the guide member 75 forms the valve body back pressure chamber 74 outside the plunger 34 as a back pressure chamber forming member, and moves slightly in the radial direction within the mounting hole 76, whereby the guide pin 71 and the guide The requirement of concentric accuracy with the hole 73 can be relaxed. The guide member 75 may be combined with the modification shown in FIG.

In the modification shown in FIG. 8, the the first embodiment, the guide pin 71 is omitted, the extension shaft portion 59 of the valve body, sliding to the rear guide hole and protrudes from the extension portion 59 is a plunger 34 It is movable and liquid-tightly inserted. A valve body back pressure chamber 74 is formed in the guide hole 73 by the extension portion 59 </ b> A of the shaft portion 59. Thereby, since the port 40 and the valve body back pressure chamber 74 are directly connected by the valve body communication path 70, the leakage from a sliding part can be suppressed. In this case, as shown in FIG. 9, a pipe member can be used as the shaft portion 59 by connecting the head portion and the shaft portion of the valve body 56 separately, thereby reducing the manufacturing cost. can do. In addition, you may combine the guide member 75 shown in FIG. 7 with the modification shown in FIG.8 and FIG.9.

In the modification shown in FIG. 10, a solid guide pin 77 is provided in place of the guide pin 71 having the communication path 72 in the first embodiment. The guide pin 77 is press-fitted and fixed in the guide hole 73 of the core 37, and is slidably and liquid-tightly inserted into the guide hole 62 of the plunger 34. Thus, the valve body back pressure chamber 74 is formed in the guide hole 62 of the plunger 34 and communicated with the port 40 through the valve body communication passage 70. In this case, the guide pin 77 is provided with a passage penetrating in the axial direction like the communication hole 72 of the guide pin 77 shown in FIG. 5 so that the valve body back pressure chamber 74 communicates with the guide hole 73 of the core 37. The volume of the valve body back pressure chamber 74 can be increased.

  Further, the guide pin 77 is not press-fitted into the guide hole 73 but is inserted into the mounting hole 76 provided in the core 37 as shown in FIG. 11, and its bottom is brought into contact with the bottom of the mounting hole 76 in the axial direction. It may be fixed. Thereby, the request | requirement of the concentric precision with the guide pin 77 and the core 37 side can be eased.

Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the same reference numerals are given to the same parts with respect to the first embodiment, and only different parts will be described in detail. 14 shows the relief valve 84, the valve element 87, the rod 88, the plunger 34, etc. in the state when the solenoid is not energized, and the valve element 87 when energized on the seat surface 60 for convenience of explanation. It is shifted to the lower side of the figure showing the seated state.

  In the present embodiment, the passage bore 39 of the solenoid case 32 and the cylindrical portion 43A of the passage member 43 screwed into the passage bore 39 are increased in diameter. A large diameter portion 81B of a stepped cylindrical port member 81 having a large diameter portion 81A and a small diameter portion 81B is inserted into the cylindrical portion 43A. In the port member 81, the port 40 and the seat surface 60 are formed, and the small diameter portion 81 </ b> B is inserted into the passage 43 </ b> B communicating with the second oil passage 86 and the fixed orifice 47 provided in the radial direction of the passage member 43. 40 communicates with the radial oil passage 86 and the fixed orifice 47. A valve chamber 83 is formed on the downstream side of the port 40 in the passage bore 39 and the cylindrical portion 43 </ b> A, and the valve chamber 83 communicates with the chamber 48 via the first oil passage 66 of the solenoid case 32. A relief valve 84 is provided between the port member 81 and the passage member 43. The valve chamber 83 and the chamber 48 are communicated with each other via an oil passage 85 formed in the port member 81, a relief valve 84, and a second oil passage 86 formed in the cylindrical portion 43A. When the pressure in the valve chamber 83 reaches a predetermined valve opening pressure, the relief valve 84 opens and relieves the pressure to the chamber 48 side. When the coil 35 is energized and when the seat portion 61 of the valve body 87 is separated from the seat surface 60, the valve body 87 is separated from both the seat surface 60 and the step portion 96. In this state, the chamber communicates mainly with the chamber 48 via the first oil passage 100 of the solenoid case 32. Since there is a relief valve 84 with the second oil passage 86, it hardly communicates. On the other hand, when the coil 35 is not energized, the sheet member 93 comes into contact with the step portion 96 to close the first oil passage 100 and only the second oil passage 86 communicates with the chamber 48.

A substantially convex valve element 87 having a small diameter portion 87A and a large diameter portion 87B is provided in the valve chamber 83. A distal end portion of a hollow rod 88 (shaft portion) attached to the plunger 34 is inserted into the valve body 87. An annular seat portion 61 that is attached to and detached from the seat surface 60 of the port member 81 protrudes from the distal end portion of the small diameter portion 87A of the valve body 87, and the pressure control valve 28 is configured by the port 40 and the valve body 87. Yes. And like the said 1st Embodiment, the recessed part 80 is formed in the inner peripheral part vicinity of the sheet | seat part 61, and the outer peripheral side of the sheet | seat part 61 is formed in the taper shape. Thereby, the influence of the fluid force can be reduced, the soft-side damping force can be made sufficiently small, and stable damping force control can be performed. An opening 89 penetrating in the axial direction is formed in the valve body 87, and the tip end portion of the rod 88 is slidably and liquid-tightly inserted into the opening 89. An annular contact portion 90 projects from the outer peripheral edge portion of the large diameter portion 87B of the valve body 87.

  The rod 88 passes through the plunger 34 and is fixed to the plunger 34. The rear end portion of the rod 88 is slidably and liquid-tightly inserted into a guide hole 73 formed in the bottom portion of the bottomed cylindrical guide member 91 that guides the rear end portion of the plunger 34. A valve body back pressure chamber 74 is formed therein. The valve body back pressure chamber 74 communicates with the recess 80 of the valve body 87 via a communication path 88 </ b> A in the hollow rod 88.

  A retaining ring 92 is fixed to a step formed on the distal end side of the rod 88. An annular seat member 93 and a valve spring 94 (plate spring) are provided between the retaining ring 92 and the contact portion 90 of the valve body 87. Is intervening. The seat member 93 and the valve spring 94 have an outer peripheral portion in contact with the contact portion 90 and an inner peripheral portion in contact with the retaining ring 92. Then, a thrust is generated in the plunger 34 by energizing the coil 35, and the valve element 87 is pressed against the spring force of the return spring 95 by the thrust of the plunger 34 as shown in the lower side of FIG. 14. The sheet part 61 is pressed against the sheet surface 60. At this time, the valve body 87 is elastically supported by the rod 88 via the valve spring 94. A return spring 95 (coil spring) as a main spring is interposed between the port member 81 and the valve body 87. On the bottom side of the passage bore 39, a step portion 96 is formed at a portion facing the contact portion 90 of the valve body 87. Then, as shown in the upper side of FIG. 14, the valve element 87 is retracted by the spring force of the return spring 95, and the seat member 93 comes into contact with the step portion 96, as shown in the upper side of FIG. 66 is closed, and the valve chamber 83 and the chamber 48 communicate with each other through the orifice 97 of the seat portion 93. The spring stiffness of the valve spring 94 is greater than the spring stiffness of the return spring 95, and the mass of the valve body 87 is sufficiently smaller than that of the plunger 34.

  With this configuration, the pressure control valve 28 is energized to the coil 35, so that the valve element resists the spring force of the return spring 95 by the thrust of the plunger 34, as shown on the lower side in FIG. The valve opening pressure is adjusted by pressing 87 and pressing the seat 61 against the seat surface 60. At this time, as in the first and second embodiments, when the pressure of the port 40 suddenly increases, the valve spring 94 bends and only the lightweight valve body 87 moves backward, and the plunger is opened. Since 34 follows and retreats, a response delay due to the inertia of the plunger 34 hardly occurs, and overdamping can be prevented and appropriate damping force control can be performed. Then, an excessive increase in the pressure in the back pressure chamber 53 due to the delay in opening the pressure control valve 28 can be suppressed, and stable damping force control can be performed. Further, it is possible to suppress the generation of abnormal noise due to the self-excited vibration of the valve body 87 and the instability of the damping force.

Similarly to the first embodiment, the valve body back pressure chamber 74 is connected to the rod 88 when the pressure control valve 28 is closed, that is, in a state where the seat portion 61 of the valve body 87 is seated on the seat surface 60. Since it communicates with the port 40 via the passage 88A, the pressure receiving area of the valve body 87 with respect to the port 40 is an area obtained by subtracting the cross-sectional area of the rod 88 from the area inside the seat 61. Thereby, the valve element 87 can adjust the pressure receiving area with respect to the port 40 not only by the diameter of the seat portion 61 but also by the diameter of the rod 88. Thus, the degree of freedom in setting the damping force characteristic of the damping force generation mechanism 25 can be increased.

  When the thrust of the plunger 34 is lost due to the failure of the controller or the failure of the coil 35 or the like, the valve element 87 is retracted by the spring force of the return spring 95 as shown on the upper side in FIG. Thus, the seat member 93 abuts on the step 96 of the passage bore 39 to close the first oil passage 100, and the valve chamber 83 and the chamber 48 are communicated by the orifice 97. When the pressure in the valve chamber 83 increases due to an increase in piston speed or the like and reaches the valve opening pressure of the relief valve 84, the relief valve 84 is opened and the pressure is released to the chamber 48.

  As a result, a damping force is generated according to the flow path area of the orifice 97 and the relief pressure of the relief valve 84, whereby the pressure in the back pressure chamber 53, that is, the valve opening pressure of the disc valve 51 is adjusted. By appropriately setting the channel area and the relief pressure, an appropriate damping force can be generated even during a failure. As shown in FIG. 13, as a result of widening the adjustment range of the damping force characteristic, even if the damping force at the time of hardware becomes considerably large, it is not a hard characteristic at the time of failure but is moderate by the orifice 97 and the relief valve 84. A damping force can be generated. For example, the influence on the vehicle body can be suppressed by setting a medium characteristic between hard and soft at the time of failure.

  1 Damping force adjusting hydraulic shock absorber (damping force adjusting shock absorber), 2 cylinder, 5 piston, 6 piston rod, 28 pressure control valve, 34 plunger, 36 plunger spring (main spring), 56 valve body, 57 valve spring

Claims (9)

A cylinder filled with fluid, a piston slidably fitted in the cylinder, a piston rod having one end connected to the piston and the other end extending outside the cylinder, In a damping force adjusting type shock absorber provided with a pressure control valve capable of adjusting a valve opening pressure by generating a damping force by controlling a flow of fluid generated by sliding of the piston,
The pressure control valve includes a valve body seated on a seat surface, a shaft portion provided in the valve body and provided with a communication passage extending in an axial direction therein, and the shaft portion being inserted to remove the valve body from the seat surface. a plunger for adjusting the valve opening pressure to urge the side, a solenoid for adjusting the thrust of the plunger, provided on the rear surface of the shaft portion, which acts to urge the valve body to the seat surface A valve body back pressure chamber, and a main spring for biasing the plunger or the valve body to a side opposite to the biasing force of the plunger ,
A main valve that generates a damping force by controlling a flow of fluid generated by sliding of the piston in the cylinder; and a back pressure chamber that applies an internal pressure to the main valve in a valve closing direction. Is introduced into the back pressure chamber, and the internal pressure of the back pressure chamber is adjusted by the pressure control valve,
The pressure receiving area of the valve body is obtained by communicating the back pressure chamber and the valve body back pressure chamber through the communication passage of the shaft portion in a state where the valve body is seated on the seat surface. A damping force adjusting type shock absorber, wherein the pressure receiving area is obtained by subtracting the area on the valve body back pressure chamber side from the area on the surface side.   The shaft portion provided in the valve body is integral with the valve body, and the shaft portion is guided in a guide hole penetrating through the center of the plunger so as to be slidable along the axial direction. The damping force adjusting type shock absorber according to claim 1,   The shaft portion provided in the valve body is separate from the valve body, and the shaft portion is fixed to a guide hole penetrating through the center of the plunger. Damping force adjustable shock absorber.   The damping force adjustable shock absorber according to claim 3, wherein the valve body is biased by the main spring toward the shaft portion.   2. The valve body according to claim 1, wherein the valve body has an annular seat portion that opens and closes on the seat surface to open and close the flow path, and a recess is formed in the vicinity of the inner peripheral portion of the seat portion. 4. Damping force adjustment type shock absorber according to any one of 4 above.   A fixed orifice for introducing fluid from the upstream side of the main valve to the back pressure chamber side, and the flow of fluid from the back pressure chamber side to the downstream side of the main valve is controlled by the pressure control valve; The damping force adjusting type shock absorber according to any one of claims 1 to 5, wherein an internal pressure of the back pressure chamber is adjusted.   The damping force adjusting type shock absorber according to any one of claims 1 to 6, wherein the main spring biases the valve body in a valve opening direction.   The pressure control valve moves the valve body in the valve opening direction by the bias of the main spring at the time of failure, closes the first flow path to the downstream side, and flows the fluid to the downstream side through the orifice. The damping force adjusting type shock absorber according to any one of claims 1 to 7, wherein the damping force adjusting type shock absorber is distributed through a path.   The damping force adjusting type shock absorber according to any one of claims 1 to 8, wherein the pressure control valve is disposed on a side portion of the cylinder.