US20020157907A1 - Parking brake for drum type brakes with electronic lining wear sensor and adjuster - Google Patents
Parking brake for drum type brakes with electronic lining wear sensor and adjuster Download PDFInfo
- Publication number
- US20020157907A1 US20020157907A1 US09/873,102 US87310201A US2002157907A1 US 20020157907 A1 US20020157907 A1 US 20020157907A1 US 87310201 A US87310201 A US 87310201A US 2002157907 A1 US2002157907 A1 US 2002157907A1
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- Prior art keywords
- brake
- strut
- drum
- power screw
- actuator subassembly
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- 230000003213 activating effect Effects 0.000 claims 1
- 230000004913 activation Effects 0.000 claims 1
- 230000009849 deactivation Effects 0.000 claims 1
- 230000007246 mechanism Effects 0.000 description 8
- 230000000712 assembly Effects 0.000 description 6
- 238000000429 assembly Methods 0.000 description 6
- 230000004044 response Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 210000005069 ears Anatomy 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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Classifications
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- 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
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/38—Slack adjusters
- F16D65/40—Slack adjusters mechanical
- F16D65/52—Slack adjusters mechanical self-acting in one direction for adjusting excessive play
- F16D65/56—Slack adjusters mechanical self-acting in one direction for adjusting excessive play with screw-thread and nut
- F16D65/561—Slack adjusters mechanical self-acting in one direction for adjusting excessive play with screw-thread and nut for mounting within the confines of a drum brake
- F16D65/563—Slack adjusters mechanical self-acting in one direction for adjusting excessive play with screw-thread and nut for mounting within the confines of a drum brake arranged adjacent to service brake actuator, e.g. on parking brake lever, and not subjected to service brake force
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- 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
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D65/00—Parts or details
- F16D65/38—Slack adjusters
- F16D2065/386—Slack adjusters driven electrically
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- 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
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
- F16D2066/003—Position, angle or speed
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- 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
- F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
- F16D2066/006—Arrangements for monitoring working conditions, e.g. wear, temperature without direct measurement of the quantity monitored, e.g. wear or temperature calculated form force and duration of braking
Definitions
- This invention relates to a leading/trailing type drum brake assembly in which the parking brake lever, adjuster strut and associated components are replaced with a single electronic subassembly that controls the parking brake, senses brake lining wear and adjusts the brake shoe-to-drum clearance to account for lining wear.
- the parking brake assembly includes a strut actuator subassembly that comprises a strut tube, an electric motor, a position encoder, a power screw and a connector fork.
- Drum brakes are a common type of vehicle brake.
- Drum brake assemblies utilize opposing arcuate brake shoes that are movable away from one another into engagement with an inner surface of a drum to slow the vehicle.
- a hydraulic wheel cylinder forces the brake shoes into engagement with the drum.
- the same brake shoes may also be used to maintain the vehicle in a parked position.
- drum brake assemblies have employed a separate mechanical linkage, or parking brake lever, that is actuated by a cable to maintain the brake shoes in engagement with the drum.
- parking brake lever Such mechanical parking brakes have presented various problems that have been partially addressed by the use of electric parking brake mechanisms.
- Some electric parking brake mechanisms have eliminated the parking brake lever and completely redesigned the drum brake assembly to incorporate an electric parking brake mechanism. These mechanisms have required high torque motors and a gearbox to generate sufficient force to apply the brakes, adding significant cost to the drum brake assembly. These high torque motors tend to be relatively large and cannot simply replace components presently included in brake drum assemblies, but instead require substantial redesign of the brake assembly package. Furthermore, high torque motors utilize a significant amount of power that is undesirable in modem vehicles.
- an electric parking brake assembly is needed that requires relatively little power to apply, that may be easily retrofitted into a conventional drum brake assembly, and that provides real-time adjustment of the brake shoe-to-drum clearance and sensing of brake lining wear.
- the present invention is directed to an electrically and hydraulically (hereinafter referred to as “electro-hydraulic”) actuated electronic parking brake assembly for a leading/trailing type automotive drum brake.
- the parking brake assembly includes a strut actuator subassembly that replaces conventional components including the parking brake lever, adjuster strut and associated parts, used in a standard drum brake.
- the strut actuator subassembly is easily incorporated into a conventional brake assembly and comprises a strut tube, an electric motor having a driveshaft, a position encoder, a power screw and a connector fork. Due to the design of the strut actuator subassembly, a low power (and low torque) motor can be used.
- the brake assembly of the present invention includes a backing plate having primary and secondary shoe hold-down pin and spring assemblies with primary and secondary brake shoes.
- Each of the brake shoes has a portion in spaced relation from one another.
- a drum is disposed about the brake shoes.
- a wheel cylinder is supported by the backing plate and is arranged between the portions of the brake shoes for forcing the portions away from one another to engage the brake shoes with the drum in a brake position.
- a strut actuator subassembly located adjacent to the wheel cylinder, interconnects the brake shoes proximate to the portions.
- the strut actuator subassembly comprises a strut tube, a power screw, a connector fork, an electric motor with a driveshaft and a position encoder.
- the strut tube has one open end having female threads along a portion of the interior and an opposing end that tapers to a two-pronged fork.
- the power screw has male threads along a portion of its length and an unthreaded rod portion at one end.
- the connector fork has an annular female receiver portion at one end suitable for receiving the rod portion of the power screw and a two-pronged fork at the other end.
- the electric motor and position encoder are located within the strut tube, and the electric motor is axially connected with the power screw via the driveshaft.
- the strut tube and the power screw connect at their respective female and male threaded ends.
- the power screw, at its rod end connects to the female end of the connector fork.
- the forked end of the strut tube and the connector fork connect with slots in portions of each web of opposing brake shoes thereby securing the strut actuator subassembly between the opposing brake shoes.
- the strut tube, electric motor with driveshaft, position encoder, power screw and connector fork are in axial relationship with one another and when connected define the transverse structure of the strut actuator subassembly.
- the strut actuator subassembly serves as a parking brake latch. Hydraulic pressure is applied by the electro-hydraulic actuator to the wheel cylinder to advance the brake shoes against the drum. As the brake is applied hydraulically, the electric motor of the strut actuator subassembly is energized. The strut actuator subassembly turns the power screw to advance the connector fork and strut tube out against the hydraulically extended brake shoes. Due to the design of the power screw, it can only be driven in positive direction. Accordingly, when the hydraulic pressure to the wheel cylinder is released along with the power to the electric motor, the brake shoes become locked to against the drum.
- the parking brake is released by the application of a hydraulic pressure sufficient to remove the axial load on the power screw, the connector fork and the strut tube.
- the electric motor then re-energizes, reverses and retracts the power screw and strut tube away from the shoes allowing them to return to their predetermined disengaged position when the hydraulic pressure is removed.
- the connector fork returns along with the return of the brake shoes by action of the return springs.
- the present invention also advantageously provides regular and precise brake adjustment and sensing of braking lining wear.
- the electric motor is periodically energized, such as during the ignition start cycle, causing the power screw to turn which advances the brake shoes out until they touch the drum.
- the motor then reverses for a predetermined number of counts of the position encoder to obtain the desired shoe-to-drum clearance.
- This provides regular and precise brake adjustment.
- the position encoder also concurrently determines the distance that the shoe has traveled and compares it with the original brake lining position to provide a reasonable estimate of a worn out lining condition. Upon such indication of wear, the position encoder sends out a signal to notify the operator of the worn lining condition.
- the above invention provides an electric parking brake mechanism that provides regular and precise brake adjustment and lining wear indication.
- the mechanism requires relatively little power to operate and may be easily incorporated, such as by retrofit, into a conventional drum brake assembly.
- FIG. 1 is a front elevation view of a drum brake assembly of the present invention.
- FIG. 2 is an exposed planar view of the strut actuator subassembly, located at section 2 - 2 of FIG. 1, showing details of the components.
- a drum brake assembly 10 for a vehicle is shown in FIG. 1.
- the assembly 10 includes a backing plate 12 having primary 14 and secondary 16 shoe hold down pin-and-spring assemblies with primary 18 and secondary 20 brake shoes supported respectively thereon.
- a drum 21 is disposed about the brake shoes 18 , 20 .
- Each of the brake shoes 18 , 20 include brake shoe webs 22 that support friction linings 24 adjacent drum 21 .
- Each of webs 22 has a portion 30 in spaced relation from the other that extends to a second portion 32 .
- an anchor block 36 is arranged between brake shoes 18 , 20 to support the second portions 32 in spaced relationship to one another.
- a wheel cylinder 40 is supported by backing plate 12 and is arranged between portions 30 of brake shoes 18 , 20 .
- Wheel cylinder 40 includes pistons on either end, as is well known, that move in opposite directions to force the portions 30 away from one another to engage brake shoes 18 , 20 with drum 21 when in a brake position. Hydraulic fluid is forced into a chamber between the pistons by a hydraulic brake actuator. Portions 30 have ears 42 that are received in indentations in the pistons (not shown). As portions 30 are forced away from one another, brake shoes 18 , 20 pivot outward about pin-and-spring assemblies 14 , 16 .
- a strut actuator subassembly 48 located at section 2 - 2 , is connected to slots 52 , 53 in webs 22 interconnecting brake shoes 18 , 20 at ends 50 , 51 adjacent wheel cylinder 40 and proximate the portions 30 .
- Opposing ends 50 , 51 of the strut actuator subassembly 48 engage webs 22 to hold the portions 30 in spaced relation.
- Ends 50 , 51 also serve to secure strut actuator subassembly 48 between brake shoes 18 , 20 within brake assembly 10 .
- Upper and lower return springs 46 , 47 interconnect the portions 30 and second portions 32 for retracting brakes shoes 18 , 20 from drum 21 against strut actuator subassembly 48 and anchor block 36 .
- anchor block 36 and strut actuator subassembly 48 together determine the spacing of brake shoes 18 , 20 from drum 21 .
- brake shoes 18 , 20 must be moved closer to drum 21 to maintain desirable brake application characteristics, such as consistent brake pedal travel and brake response time.
- strut actuator subassembly 48 serves as a lining wear sensor and a brake shoe-to-drum clearance adjuster to accommodate for wear in brake shoes 18 , 20 .
- strut actuator subassembly 48 comprises a strut tube 54 that is open at one end having female threads and tapers to a fork at opposite end 50 .
- Strut actuator assembly 48 further comprises an electric motor 56 with a driveshaft 57 , a position encoder 58 , a power screw 60 having male threads along a portion of its length and a unthreaded rod portion at one end, and a connector fork 62 having a female end suitable to receive the rod portion of the power screw and a fork at end 51 .
- electric motor 56 and position encoder 58 are located within strut tube 54 .
- the electric motor 56 is axially connected via driveshaft 57 to power screw 60 .
- Power screw 60 connects via its rod portion to connector fork 62 that connects at end 51 with slot 53 , and strut tube 54 connects with its fork at end 50 with slot 52 .
- the electric motor 56 turns driveshaft 57 to rotate power screw 60 .
- Power screw 60 advances connector fork 62 and strut tube 54 in opposing directions.
- power screw 60 (with connector fork 62 ) and strut tube 54 move outwardly to engage brake shoes 18 , 20 with drum 21 . This outward movement provides for parking brake engagement, sensing of brake lining wear and determination of the shoe-to-drum distance.
- the electric parking brake of the present invention is actuated in response to a parking brake signal received from an electro-hydraulic parking brake mechanism (not shown). Hydraulic pressure is applied by an electro-hydraulic actuator (also not shown) to the wheel cylinder 40 that advances brake shoes 18 , 20 against the drum 21 .
- the electro-hydraulic actuator concurrently sends a signal to the strut actuator subassembly 48 to energize electric motor 56 .
- Electric motor 56 turns driveshaft 57 in the positive direction moving power screw 60 (with connector fork 62 ) and strut tube 54 outwardly to engage the brake shoes 18 , 20 with the drum 21 .
- the parking brake is released when the electro-hydraulic actuator is re-initiated by application of a hydraulic pressure that is sufficient to remove the axial load on the power screw 60 , connector fork 62 and the strut tube 54 .
- the electric motor 56 is concurrently re-energized, reverses the direction of driveshaft 57 and retracts power screw 60 and strut tube 54 , allowing brake shoes 18 , 20 to return to a disengaged position.
- Brake lining wear sensing and adjustment are also controlled by the strut actuator subassembly 48 .
- position encoder 58 records the original position of the brake shoes according to the pre-selected brake-to-drum clearance.
- the electric motor 56 is periodically energized, such as during the ignition start cycle, causing the power screw 60 (with connector fork 62 ) and the strut tube 54 to move outwardly and advance the brake shoes 18 , 20 out until they touch the drum 21 .
- the electric motor 56 then reverses for a predetermined number of counts according to position encoder 58 to obtain the desired shoe-to-drum clearance.
- the position encoder 58 concurrently determines the distance that brake shoes 18 , 20 have traveled and compares it with the original set-point position.
- the position encoder 58 outputs a signal to notify the operator of a worn brake lining condition when a predefined point is reached.
- electric motor 56 is preferably a low power, low torque motor since it need only generate enough force to move the weight of the brake shoes 18 , 20 against the resistance of return spring 46 to touch drum 21 .
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Braking Arrangements (AREA)
Abstract
Description
- This invention relates to a leading/trailing type drum brake assembly in which the parking brake lever, adjuster strut and associated components are replaced with a single electronic subassembly that controls the parking brake, senses brake lining wear and adjusts the brake shoe-to-drum clearance to account for lining wear. The parking brake assembly includes a strut actuator subassembly that comprises a strut tube, an electric motor, a position encoder, a power screw and a connector fork.
- Vehicle brakes are used to slow the vehicle and also to maintain the vehicle in a parked position. Drum brakes are a common type of vehicle brake. Drum brake assemblies utilize opposing arcuate brake shoes that are movable away from one another into engagement with an inner surface of a drum to slow the vehicle. Typically, a hydraulic wheel cylinder forces the brake shoes into engagement with the drum. The same brake shoes may also be used to maintain the vehicle in a parked position. For example, drum brake assemblies have employed a separate mechanical linkage, or parking brake lever, that is actuated by a cable to maintain the brake shoes in engagement with the drum. Such mechanical parking brakes have presented various problems that have been partially addressed by the use of electric parking brake mechanisms.
- Some electric parking brake mechanisms have eliminated the parking brake lever and completely redesigned the drum brake assembly to incorporate an electric parking brake mechanism. These mechanisms have required high torque motors and a gearbox to generate sufficient force to apply the brakes, adding significant cost to the drum brake assembly. These high torque motors tend to be relatively large and cannot simply replace components presently included in brake drum assemblies, but instead require substantial redesign of the brake assembly package. Furthermore, high torque motors utilize a significant amount of power that is undesirable in modem vehicles.
- Presently available electric brake systems have the further disadvantage that they rely on conventional brake adjustment mechanisms. Such conventional adjustment systems are mechanical and only operate when the wheels are moving in a reverse direction. In addition, neither known electric brake systems nor conventional brake systems provide real-time sensing of brake lining wear and determination of a worn brake lining condition.
- Therefore, an electric parking brake assembly is needed that requires relatively little power to apply, that may be easily retrofitted into a conventional drum brake assembly, and that provides real-time adjustment of the brake shoe-to-drum clearance and sensing of brake lining wear.
- The present invention is directed to an electrically and hydraulically (hereinafter referred to as “electro-hydraulic”) actuated electronic parking brake assembly for a leading/trailing type automotive drum brake. The parking brake assembly includes a strut actuator subassembly that replaces conventional components including the parking brake lever, adjuster strut and associated parts, used in a standard drum brake. The strut actuator subassembly is easily incorporated into a conventional brake assembly and comprises a strut tube, an electric motor having a driveshaft, a position encoder, a power screw and a connector fork. Due to the design of the strut actuator subassembly, a low power (and low torque) motor can be used.
- The brake assembly of the present invention includes a backing plate having primary and secondary shoe hold-down pin and spring assemblies with primary and secondary brake shoes. Each of the brake shoes has a portion in spaced relation from one another. A drum is disposed about the brake shoes. A wheel cylinder is supported by the backing plate and is arranged between the portions of the brake shoes for forcing the portions away from one another to engage the brake shoes with the drum in a brake position. A strut actuator subassembly, located adjacent to the wheel cylinder, interconnects the brake shoes proximate to the portions. The strut actuator subassembly comprises a strut tube, a power screw, a connector fork, an electric motor with a driveshaft and a position encoder. The strut tube has one open end having female threads along a portion of the interior and an opposing end that tapers to a two-pronged fork. The power screw has male threads along a portion of its length and an unthreaded rod portion at one end. The connector fork has an annular female receiver portion at one end suitable for receiving the rod portion of the power screw and a two-pronged fork at the other end. The electric motor and position encoder are located within the strut tube, and the electric motor is axially connected with the power screw via the driveshaft. The strut tube and the power screw connect at their respective female and male threaded ends. The power screw, at its rod end, connects to the female end of the connector fork. The forked end of the strut tube and the connector fork connect with slots in portions of each web of opposing brake shoes thereby securing the strut actuator subassembly between the opposing brake shoes. The strut tube, electric motor with driveshaft, position encoder, power screw and connector fork are in axial relationship with one another and when connected define the transverse structure of the strut actuator subassembly.
- In operation of an electro-hydraulic apply parking brake of the present invention, the strut actuator subassembly serves as a parking brake latch. Hydraulic pressure is applied by the electro-hydraulic actuator to the wheel cylinder to advance the brake shoes against the drum. As the brake is applied hydraulically, the electric motor of the strut actuator subassembly is energized. The strut actuator subassembly turns the power screw to advance the connector fork and strut tube out against the hydraulically extended brake shoes. Due to the design of the power screw, it can only be driven in positive direction. Accordingly, when the hydraulic pressure to the wheel cylinder is released along with the power to the electric motor, the brake shoes become locked to against the drum. The parking brake is released by the application of a hydraulic pressure sufficient to remove the axial load on the power screw, the connector fork and the strut tube. The electric motor then re-energizes, reverses and retracts the power screw and strut tube away from the shoes allowing them to return to their predetermined disengaged position when the hydraulic pressure is removed. The connector fork returns along with the return of the brake shoes by action of the return springs.
- The present invention also advantageously provides regular and precise brake adjustment and sensing of braking lining wear. During operation, the electric motor is periodically energized, such as during the ignition start cycle, causing the power screw to turn which advances the brake shoes out until they touch the drum. The motor then reverses for a predetermined number of counts of the position encoder to obtain the desired shoe-to-drum clearance. This provides regular and precise brake adjustment. The position encoder also concurrently determines the distance that the shoe has traveled and compares it with the original brake lining position to provide a reasonable estimate of a worn out lining condition. Upon such indication of wear, the position encoder sends out a signal to notify the operator of the worn lining condition.
- Accordingly, the above invention provides an electric parking brake mechanism that provides regular and precise brake adjustment and lining wear indication. The mechanism requires relatively little power to operate and may be easily incorporated, such as by retrofit, into a conventional drum brake assembly.
- Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:
- FIG. 1 is a front elevation view of a drum brake assembly of the present invention.
- FIG. 2 is an exposed planar view of the strut actuator subassembly, located at section2-2 of FIG. 1, showing details of the components.
- A
drum brake assembly 10 for a vehicle is shown in FIG. 1. Theassembly 10 includes abacking plate 12 having primary 14 and secondary 16 shoe hold down pin-and-spring assemblies with primary 18 and secondary 20 brake shoes supported respectively thereon. Adrum 21 is disposed about thebrake shoes brake shoes brake shoe webs 22 that supportfriction linings 24adjacent drum 21. Each ofwebs 22 has aportion 30 in spaced relation from the other that extends to asecond portion 32. Preferably, an anchor block 36 is arranged betweenbrake shoes second portions 32 in spaced relationship to one another. - A
wheel cylinder 40 is supported by backingplate 12 and is arranged betweenportions 30 ofbrake shoes Wheel cylinder 40 includes pistons on either end, as is well known, that move in opposite directions to force theportions 30 away from one another to engagebrake shoes drum 21 when in a brake position. Hydraulic fluid is forced into a chamber between the pistons by a hydraulic brake actuator.Portions 30 haveears 42 that are received in indentations in the pistons (not shown). Asportions 30 are forced away from one another,brake shoes spring assemblies - A
strut actuator subassembly 48, located at section 2-2, is connected toslots 52, 53 inwebs 22 interconnectingbrake shoes adjacent wheel cylinder 40 and proximate theportions 30. Opposing ends 50, 51 of thestrut actuator subassembly 48 engagewebs 22 to hold theportions 30 in spaced relation. Ends 50, 51 also serve to securestrut actuator subassembly 48 betweenbrake shoes brake assembly 10. Upper and lower return springs 46, 47 interconnect theportions 30 andsecond portions 32 for retractingbrakes shoes drum 21 againststrut actuator subassembly 48 and anchor block 36. In this manner, anchor block 36 andstrut actuator subassembly 48 together determine the spacing ofbrake shoes drum 21. Aslinings 24 wear,brake shoes strut actuator subassembly 48 serves as a lining wear sensor and a brake shoe-to-drum clearance adjuster to accommodate for wear inbrake shoes - Referring to FIG. 2,
strut actuator subassembly 48 comprises astrut tube 54 that is open at one end having female threads and tapers to a fork atopposite end 50.Strut actuator assembly 48 further comprises anelectric motor 56 with adriveshaft 57, aposition encoder 58, apower screw 60 having male threads along a portion of its length and a unthreaded rod portion at one end, and a connector fork 62 having a female end suitable to receive the rod portion of the power screw and a fork atend 51. As shown in FIG. 1,electric motor 56 andposition encoder 58 are located withinstrut tube 54. Theelectric motor 56 is axially connected viadriveshaft 57 topower screw 60.Power screw 60 connects via its rod portion to connector fork 62 that connects atend 51 with slot 53, and struttube 54 connects with its fork atend 50 withslot 52. In operation, theelectric motor 56 turnsdriveshaft 57 to rotatepower screw 60.Power screw 60 advances connector fork 62 and struttube 54 in opposing directions. Whenelectric motor 56 is operating in the positive direction, power screw 60 (with connector fork 62) and struttube 54 move outwardly to engagebrake shoes drum 21. This outward movement provides for parking brake engagement, sensing of brake lining wear and determination of the shoe-to-drum distance. When the motor is operating in the reverse direction,power screw 60 and struttube 54 move inwardly allowing thebrake shoes drum 21 and return to their disengaged position. This inward movement provides for parking brake disengagement and adjustment of the brakes to a pre-selected brake shoe-to-drum clearance. - The electric parking brake of the present invention is actuated in response to a parking brake signal received from an electro-hydraulic parking brake mechanism (not shown). Hydraulic pressure is applied by an electro-hydraulic actuator (also not shown) to the
wheel cylinder 40 that advancesbrake shoes drum 21. The electro-hydraulic actuator concurrently sends a signal to thestrut actuator subassembly 48 to energizeelectric motor 56.Electric motor 56 turnsdriveshaft 57 in the positive direction moving power screw 60 (with connector fork 62) and struttube 54 outwardly to engage thebrake shoes drum 21. Because thepower screw 60 cannot be driven backwards, when the hydraulic pressure towheel cylinder 40 is released with the power to theelectric motor 56, thebrake shoes drum 21. The parking brake is released when the electro-hydraulic actuator is re-initiated by application of a hydraulic pressure that is sufficient to remove the axial load on thepower screw 60, connector fork 62 and thestrut tube 54. Theelectric motor 56 is concurrently re-energized, reverses the direction ofdriveshaft 57 and retractspower screw 60 and struttube 54, allowingbrake shoes - Brake lining wear sensing and adjustment are also controlled by the
strut actuator subassembly 48. Upon brake installation, position encoder 58 records the original position of the brake shoes according to the pre-selected brake-to-drum clearance. Then, during operation, theelectric motor 56 is periodically energized, such as during the ignition start cycle, causing the power screw 60 (with connector fork 62) and thestrut tube 54 to move outwardly and advance thebrake shoes drum 21. Theelectric motor 56 then reverses for a predetermined number of counts according toposition encoder 58 to obtain the desired shoe-to-drum clearance. The position encoder 58 concurrently determines the distance thatbrake shoes - In the present invention,
electric motor 56 is preferably a low power, low torque motor since it need only generate enough force to move the weight of thebrake shoes return spring 46 to touchdrum 21. - The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
Claims (7)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US09/873,102 US6460660B1 (en) | 2001-04-26 | 2001-04-26 | Parking brake for drum type brakes with electronic lining wear sensor and adjuster |
Applications Claiming Priority (1)
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US09/873,102 US6460660B1 (en) | 2001-04-26 | 2001-04-26 | Parking brake for drum type brakes with electronic lining wear sensor and adjuster |
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US6460660B1 US6460660B1 (en) | 2002-10-08 |
US20020157907A1 true US20020157907A1 (en) | 2002-10-31 |
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US09/873,102 Expired - Lifetime US6460660B1 (en) | 2001-04-26 | 2001-04-26 | Parking brake for drum type brakes with electronic lining wear sensor and adjuster |
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Cited By (5)
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US20060071546A1 (en) * | 2004-09-30 | 2006-04-06 | Honda Motor Co., Ltd. | Vehicle brake system |
KR101532231B1 (en) * | 2014-07-23 | 2015-07-01 | 현대모비스 주식회사 | Braking device for vehicle |
FR3121488A1 (en) * | 2021-03-30 | 2022-10-07 | Psa Automobiles Sa | DRUM BRAKE DEVICE WITH SAFELY RELEASED PARKING BRAKE |
EP4187118A1 (en) * | 2021-11-30 | 2023-05-31 | KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH | Method and device for wear compensation in a braking system of vehicles |
WO2023177126A1 (en) * | 2022-03-15 | 2023-09-21 | 에이치엘만도 주식회사 | Drum brake device |
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FR2824118A1 (en) * | 2001-04-25 | 2002-10-31 | Delphi Tech Inc | DRUM BRAKE AND WEAR DETECTOR FOR SUCH A BRAKE |
US6997521B2 (en) | 2002-09-06 | 2006-02-14 | Caterpillar Inc. | Parking and service brake control system for a vehicle |
US20040124042A1 (en) * | 2002-12-31 | 2004-07-01 | Kriz Richard James | Electric mechanical brake assembly having a worm or cluster gear set |
US20040140710A1 (en) * | 2003-01-17 | 2004-07-22 | Delphi Technologies Inc. | Apparatus and method for controlling an electric park brake |
EP2198180B1 (en) * | 2007-09-05 | 2014-08-27 | Continental Teves AG & Co. oHG | Electromechanically activatable parking brake for motor vehicles, and method for activating the same |
US20250146549A1 (en) * | 2023-11-07 | 2025-05-08 | Arvinmeritor Technology, Llc | Drum brake assembly and wear sensor device |
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US4146117A (en) | 1975-12-29 | 1979-03-27 | Toyota Jidosha Kogyo Kabushiki Kaisha | Device for adjusting clearance between brake shoe and brake drum |
JPS5620842A (en) * | 1979-07-30 | 1981-02-26 | Akebono Brake Ind Co Ltd | Motor-driven auto-adjuster |
US4623045A (en) * | 1984-07-13 | 1986-11-18 | Kelsey-Hayes Company | Automatic brake adjusting mechanism |
JPH0714664Y2 (en) | 1989-05-16 | 1995-04-10 | 曙ブレーキ工業株式会社 | Drum brake |
US5148894A (en) | 1990-10-11 | 1992-09-22 | Allied-Signal Inc. | Disk brake/parking brake with threaded piston rod and motor |
US5150773A (en) | 1991-03-21 | 1992-09-29 | General Motors Corporation | Electrically actuated electric brake with wear compensating adjuster |
US5219049A (en) * | 1991-06-24 | 1993-06-15 | General Motors Corporation | Electrically actuated electric brake with adjuster |
DE4330440A1 (en) | 1993-09-08 | 1995-03-09 | Knorr Bremse Ag | Force generating device for generating a reversible working stroke |
US5769189A (en) | 1995-03-03 | 1998-06-23 | Lucas Industries Public Limited Company | Automotive parking brake and parking brake system for motor vehicles |
-
2001
- 2001-04-26 US US09/873,102 patent/US6460660B1/en not_active Expired - Lifetime
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060071546A1 (en) * | 2004-09-30 | 2006-04-06 | Honda Motor Co., Ltd. | Vehicle brake system |
US7802663B2 (en) * | 2004-09-30 | 2010-09-28 | Honda Motor Co., Ltd. | Vehicle brake system |
KR101532231B1 (en) * | 2014-07-23 | 2015-07-01 | 현대모비스 주식회사 | Braking device for vehicle |
FR3121488A1 (en) * | 2021-03-30 | 2022-10-07 | Psa Automobiles Sa | DRUM BRAKE DEVICE WITH SAFELY RELEASED PARKING BRAKE |
EP4187118A1 (en) * | 2021-11-30 | 2023-05-31 | KNORR-BREMSE Systeme für Nutzfahrzeuge GmbH | Method and device for wear compensation in a braking system of vehicles |
WO2023177126A1 (en) * | 2022-03-15 | 2023-09-21 | 에이치엘만도 주식회사 | Drum brake device |
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US6460660B1 (en) | 2002-10-08 |
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