A type of automotive parking brake shoe assembly

Abstract

This application relates to a parking brake shoe assembly for automobiles, comprising a backing plate and a brake drum. A brake shoe is rotatably mounted on the backing plate. The backing plate has a first driving member for driving the brake shoe towards the inner wall of the brake drum, and a first elastic member for driving the brake shoe away from the inner wall of the brake drum. A shoe plate is slidably mounted on the brake shoe, and a friction pad is fixedly mounted on the shoe plate. A positioning plate is slidably mounted on the brake shoe along the axial direction of the brake drum. A transmission member is mounted on the brake shoe for driving the positioning plate to slide. A second elastic member is mounted on the brake shoe for driving the shoe plate to slide away from the brake shoe, and the friction pad abuts against the positioning plate. A limiting component is mounted on the brake shoe to prevent the shoe plate from sliding. This application allows the braking response time to be controlled within a relatively stable range, thereby significantly reducing the possibility of traffic accidents caused by untimely braking.

Description

Technical Field

[0001] This application relates to the technical field of vehicle parts, and in particular to an automotive parking brake shoe assembly. Background Technology

[0002] Vehicle brakes are an important component of vehicles and are key to ensuring driving safety. Currently, commonly used vehicle brakes include drum brakes and disc brakes. The brake shoes are the friction pairs of drum brakes. In addition to having the strength and rigidity required as components, they should also have the highest possible and most stable coefficient of friction, as well as appropriate wear resistance, heat resistance, heat dissipation and heat capacity.

[0003] Currently, brake shoes mainly consist of components such as backing plate, brake drum, brake shoes, wheel cylinder, and return spring. The brake drum is mounted on the wheel hub and rotates with the wheel. The brake shoes are pressed and mounted on the backing plate by screws with springs. Friction pads are installed on the brake shoes. When braking, the wheel cylinder piston pushes the brake shoes to deflect, and the friction pads press against the brake drum. The brake drum is decelerated by friction, thereby forcing the wheel to stop rotating.

[0004] However, after a certain period of use, the friction pads on the brake shoes wear down, and the distance between the friction pads and the brake drum increases, which makes the brake response time longer and can easily cause traffic accidents due to untimely braking. Summary of the Invention

[0005] In view of the problems existing in the prior art, this application provides a parking brake shoe assembly for automobiles, which can effectively adjust the braking response time when the brake pads are worn, and reduce the possibility of traffic accidents caused by untimely braking.

[0006] This application provides a parking brake shoe assembly for automobiles, which adopts the following technical solution:

[0007] A parking brake shoe assembly for automobiles includes a back plate fixedly mounted on the vehicle body and a brake drum fixedly mounted on the vehicle wheel hub. A brake shoe is rotatably mounted on the back plate and is located inside the brake drum. The brake shoe deflects in a direction close to or away from the inner wall of the brake drum. A first driving member is provided on the back plate for driving the brake shoe to deflect in a direction close to the inner wall of the brake drum. A first elastic member is also provided on the back plate for driving the brake shoe to deflect in a direction away from the inner wall of the brake drum.

[0008] A shoe plate is slidably disposed on the brake shoe, a friction plate is fixedly disposed on the shoe plate, a positioning plate is slidably disposed on the brake shoe along the axial direction of the brake drum, a transmission component is disposed on the brake shoe to drive the positioning plate to slide, a second elastic component is disposed on the brake shoe to drive the shoe plate to slide away from the brake shoe, and the friction plate is used to abut against the positioning plate, and a limiting component is disposed on the brake shoe to prevent the shoe plate from sliding.

[0009] By adopting the above technical solution, when the vehicle is in motion, the brake shoe, under the elastic force of the second elastic element, causes the friction pad to abut against the positioning plate, controlling the distance between the friction pad and the inner wall of the brake drum. When braking is required, the limiting component prevents the brake shoe from sliding on the brake shoe, the transmission component drives the positioning plate to slide and disengage from the friction pad, and the first driving component drives the brake shoe to deflect towards the inner wall of the brake drum. The friction pad squeezes the brake drum, and the brake drum is decelerated by friction, thereby forcing the wheel to stop rotating.

[0010] After the first driving component releases the force, the first elastic component drives the brake shoe to deflect away from the inner wall of the brake drum. The transmission component continues to drive the positioning plate to slide to the travel path of the friction pad. The limiting component is released, and the friction pad continues to abut against the positioning plate under the elastic force of the second elastic component. This ensures that the distance between the friction pad and the inner wall of the brake drum remains consistent each time the brake is applied, and the braking response time can be controlled within a relatively stable range, thereby greatly reducing the possibility of traffic accidents caused by untimely braking.

[0011] Optionally, the limiting component includes a top block and a second driving member. The top block is slidably disposed on the brake shoe in a direction close to or away from the side wall of the shoe plate. A first friction surface is provided at one end of the top block close to the shoe plate, and a second friction surface is provided at one end of the shoe plate close to the top block. The second driving member is used to drive the top block to slide.

[0012] By adopting the above technical solution, the top block is driven to slide closer to the shoe plate by the second driving component, so that the first friction surface on the top block is pressed against the second friction surface on the shoe plate, and a sufficiently large static friction force is generated between the top block and the shoe plate, thereby preventing the shoe plate from sliding on the brake shoe.

[0013] Optionally, the top block has a groove at one end away from the shoe plate, and a top rod is slidably disposed in the groove, with the length direction of the top rod parallel to the sliding direction of the top block. The top block is provided with a third elastic element for driving the top rod to slide away from the top block, and the second driving element is used to drive the top rod to slide. The transmission element includes a transmission rod, one end of which is fixedly connected to the top rod. The transmission rod extends to the side of the brake shoe away from the hydraulic cylinder, and the positioning plate is disposed on the transmission rod.

[0014] By adopting the above technical solution, the push rod is driven to slide by the second driving component. The push rod drives the push block to slide and drives the positioning plate to slide through the transmission rod. After the push block slides a certain distance, the first friction surface on the push block abuts against the second friction surface on the shoe plate. Under the elastic force of the third elastic component, the push block pre-presses the shoe plate. Then, the push rod continues to slide and slides in the groove of the push block, which continues to make the positioning plate slide, thereby causing the positioning plate to separate from the friction plate.

[0015] Optionally, the third elastic element includes a support spring, and the bottom wall of the slide groove is provided with a placement groove communicating with the slide groove along the length direction of the top rod, and the support spring is disposed in the placement groove.

[0016] By adopting the above technical solution, the support spring is placed in the placement groove, which to some extent prevents the support spring from being crushed.

[0017] Optionally, the transmission rod has an elongated groove along the direction close to or away from the brake shoe, a slider is slidably disposed in the elongated groove, the positioning plate is fixedly connected to the slider, and the transmission rod is provided with a limiting member to prevent the slider from sliding.

[0018] By adopting the above technical solution, the distance between the positioning plate and the brake shoe can be adjusted by sliding the slider, and the slider can be prevented from sliding by the limiting component. This allows the brake response time to be adjusted according to actual needs, further increasing practicality.

[0019] Optionally, the limiting component includes a limiting screw, which is rotatably mounted on the transmission rod, and the axial direction of the limiting screw is parallel to the sliding direction of the slider, and the limiting screw is threadedly engaged with the slider.

[0020] By adopting the above technical solution, the slider can be moved to slide in the long groove by rotating the limiting screw. When the limiting screw stops rotating, the slider can be prevented from sliding.

[0021] Optionally, the positioning plate has a plurality of spherical grooves at one end near the friction plate, each spherical groove being provided with a ball, and one end of the ball extending outside the spherical groove and used for rolling connection with the friction plate.

[0022] By adopting the above technical solution, when the friction plate comes into contact with the positioning plate, the sliding of the positioning plate will generate a certain amount of friction between it and the friction plate. Over time, this will easily cause the positioning plate to wear out. By using ball bearings, the friction between the positioning plate and the friction plate can be reduced, thereby increasing the service life of the positioning plate.

[0023] Optionally, the friction pad is detachably mounted on the shoe plate, and the shoe plate is provided with a fixing member for fixing the friction pad.

[0024] By adopting the above technical solution, when the friction plate is worn, it can be replaced simply by loosening the fixing parts and removing the friction plate from the shoe plate, thus further increasing its practicality.

[0025] Optionally, a fixing sleeve is fixedly provided on the back plate, and a locking gear is slidably provided on the fixing sleeve. The axial direction of the locking gear coincides with the central axis of the brake drum. A toothed sleeve is coaxially fixedly provided inside the brake drum. The toothed sleeve is adapted to the locking gear. A third driving member for driving the locking gear to slide is provided on the back plate.

[0026] By adopting the above technical solution, when the friction pads are damaged and not replaced in time, or when the first or second drive component fails and the brakes fail, the locking gear can be driven to slide by the third drive component and inserted into the gear sleeve to perform emergency braking on the brake drum, thereby stopping the vehicle and further improving driving safety.

[0027] Optionally, a push ring is slidably disposed on the fixed sleeve along the axial direction of the locking gear. The push ring is disposed between the locking gear and the back plate. A fourth elastic element is disposed on the push ring for driving the locking gear to slide away from the push ring. The third driving element is used to drive the push ring to slide.

[0028] By adopting the above technical solution, when the locking gear is inserted into the toothed sleeve, there is usually an inaccurate alignment between the locking gear and the toothed sleeve. The third driving component drives the push ring to slide, and the fourth elastic component drives the locking gear to slide. When the locking gear comes into contact with the toothed sleeve, the fourth elastic component is compressed, and the toothed sleeve continues to rotate with the brake drum. When the toothed sleeve rotates to a certain angle, the locking gear and the toothed sleeve are aligned and inserted into the toothed sleeve under the elastic force of the fourth elastic component, thus achieving emergency braking.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. After the first driving component unloads the force, the first elastic component drives the brake shoe to deflect away from the inner wall of the brake drum. The transmission component continues to drive the positioning plate to slide to the travel path of the friction plate. The limiting component is released, and the friction plate continues to abut against the positioning plate under the elastic force of the second elastic component. This ensures that the distance between the friction plate and the inner wall of the brake drum remains consistent each time the brake is applied, and the braking response time can be controlled within a relatively stable range, thereby greatly reducing the possibility of traffic accidents caused by untimely braking.

[0031] 2. When the friction pads are damaged and not replaced in time, or when the first or second drive component fails, causing brake failure, the locking gear can be driven to slide by the third drive component and inserted into the gear sleeve to apply emergency braking to the brake drum, thereby stopping the vehicle and further improving driving safety.

[0032] 3. When the locking gear is inserted into the toothed sleeve, there is usually a misalignment between the locking gear and the toothed sleeve. The third driving component drives the push ring to slide, and the fourth elastic component drives the locking gear to slide. When the locking gear comes into contact with the toothed sleeve, the fourth elastic component is compressed, and the toothed sleeve continues to rotate with the brake drum. When the toothed sleeve rotates to a certain angle, the locking gear and the toothed sleeve are aligned and the locking gear is inserted into the toothed sleeve under the elastic force of the fourth elastic component, thus achieving emergency braking. Attached Figure Description

[0033] Figure 1 This is an exploded view of an embodiment of this application;

[0034] Figure 2 This is a structural cross-sectional view of an embodiment of this application;

[0035] Figure 3 yes Figure 2 Enlarged view of section A;

[0036] Figure 4 This is a partial structural cross-sectional view of an embodiment of this application;

[0037] Figure 5 yes Figure 4 A magnified view of section B.

[0038] Explanation of reference numerals in the attached drawings: 1. Back plate; 11. First driving component; 12. First elastic component; 13. Fixing sleeve; 131. Locking gear; 132. Push ring; 133. Fourth elastic component; 14. Third driving component; 2. Brake drum; 21. Gear sleeve; 3. Brake shoe; 31. Friction plate; 311. Mounting block; 32. Mounting groove; 33. Shoe plate; 331. Fixing component; 34. Second elastic component; 35. Positioning plate; 36. Transmission rod; 361. Long groove; 362. Slider; 363. Limiting screw; 4. Limiting assembly; 41. Top block; 411. Slide groove; 412. Top rod; 413. Third elastic component; 414. Placement groove; 42. Second driving component. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0040] This application discloses an automotive parking brake shoe assembly. (Refer to...) Figure 1The system includes a back plate 1 fixedly mounted on the vehicle body and a brake drum 2 fixedly mounted on the vehicle wheel hub. The back plate 1 has a through hole in the middle through which the vehicle wheel axle passes. Two brake shoes 3 are rotatably mounted on the back plate 1. Both brake shoes 3 are located inside the brake drum 2. Both brake shoes 3 are provided with friction pads 31. The back plate 1 is provided with a first driving member 11 for driving the two brake shoes 3 to deflect in a direction away from each other. The back plate 1 is also provided with a first elastic member 12 for driving the two brake shoes 3 to deflect in a direction close to each other.

[0041] Reference Figure 1 The first driving component 11 includes a bidirectional hydraulic cylinder, which is fixedly mounted on the back plate 1 and located between the two brake shoes 3; the first elastic component 12 includes a tension spring, which is located between the two brake shoes 3 and its two ends are fixedly connected to the two brake shoes 3 respectively. When not braking, the two brake shoes 3 deflect towards the bidirectional hydraulic cylinder under the elastic force of the tension spring and abut against the two piston rods of the bidirectional hydraulic cylinder respectively.

[0042] Reference Figure 2 A fixing sleeve 13 is fixedly installed on the back plate 1. The fixing sleeve 13 communicates with the through hole and is used to be sleeved on the automobile wheel axle. A locking gear 131 is slidably sleeved on the fixing sleeve 13 along the axial direction of the fixing sleeve 13. A first limiting block is fixedly installed on the locking gear 131. A first limiting groove is opened on the side wall of the fixing sleeve 13 along the axial direction of the fixing sleeve 13. The first limiting block is slidably installed in the first limiting groove. A toothed sleeve 21 is coaxially fixedly installed inside the brake drum 2. The toothed sleeve 21 is adapted to the locking gear 131. When the brake shoe assembly is installed on the vehicle, the central axis of the locking gear 131 and the toothed sleeve 21 coincides.

[0043] Reference Figure 2 A push ring 132 is slidably sleeved on the fixed sleeve 13 and located between the locking gear 131 and the back plate 1. The push ring 132 is provided with a fourth elastic element 133 for driving the locking gear 131 to slide away from the push ring 132. The fourth elastic element 133 includes a return spring, which is sleeved on the fixed sleeve 13 and located between the push ring 132 and the locking gear 131. The two ends of the return spring are fixedly connected to the push ring 132 and the locking gear 131, respectively. A third driving element 14 is provided on the back plate 1 for driving the push ring 132 to slide. The third driving element 14 includes an electric cylinder, which is fixedly located at the end of the back plate 1 away from the fixed sleeve 13. The piston rod of the electric cylinder passes through the back plate 1 and is fixedly connected to the push ring 132.

[0044] Since the locking gear 131 is inserted into the sleeve 21, the vehicle will generate a very large torque during emergency braking. The faster the vehicle travels, the greater the torque will be. When the torque is large enough, it can easily damage the brake shoe assembly. Therefore, the locking gear 131 and the sleeve 21 are only used when the vehicle is parked, traveling at low speed, or when a sudden emergency occurs.

[0045] Reference Figure 2 The back plate 1 has two arc-shaped holes, and the two brake shoes 3 each have mounting holes. The mounting holes correspond to the positions of the arc-shaped holes. When installing the brake shoes 3, the bolt is passed through the mounting holes and the arc-shaped holes, the first compression spring is fitted on the bolt, and the nut is fitted on the bolt, so that one end of the first compression spring abuts against the head of the bolt, and the other end of the first compression spring abuts against the brake shoes 3, so that when the brake shoes 3 are rotated and mounted on the back plate 1, they always have a clamping force in the direction of approaching the back plate 1.

[0046] Reference Figure 4 The brake shoe 3 has an installation groove 32 at the end away from the bidirectional hydraulic cylinder. A shoe plate 33 is slidably arranged in the installation groove 32. A second limiting groove is provided on the side wall of the shoe plate 33. A second limiting block is fixedly arranged on the shoe plate 33. The second limiting block is slidably arranged in the second limiting groove.

[0047] Reference Figure 3 , 5 The brake shoe 33 has a receiving groove at the end away from the brake shoe 3. A mounting block 311, adapted to the receiving groove, is fixedly mounted on the friction plate 31. The brake shoe 33 has a fixing member 331 for fixing the mounting block 311, which includes screws. By inserting the mounting block 311 on the friction plate 31 into the receiving groove of the brake shoe 33 and fixing the brake shoe 33 to the mounting block 311 with screws, the friction plate 31 can be mounted on the brake shoe 33. Mounting the friction plate 31 in the receiving groove also increases the stability of the friction plate 31 on the brake shoe 33.

[0048] Reference Figure 4 The brake shoe 3 is provided with a second elastic element 34 for driving the shoe plate 33 to slide away from the brake shoe 3. The second elastic element 34 includes a second compression spring. Multiple second compression springs are provided, and all multiple second compression springs are provided in the mounting groove 32. One end of the second compression spring is fixedly connected to the bottom wall of the mounting groove 32, and the other end of the second compression spring is fixedly connected to the shoe plate 33.

[0049] Reference Figure 4 , 5The brake shoe 3 is provided with a limiting component 4 for preventing the shoe plate 33 from sliding. The limiting component 4 includes a top block 41 and a second driving member 42. The top block 41 is slidably disposed on the brake shoe 3 along the sliding direction perpendicular to the shoe plate 33. A groove 411 is formed on the end of the top block 41 away from the shoe plate 33 along the sliding direction of the top block 41. A top rod 412 is slidably disposed in the groove 411. A third limiting block is fixedly disposed on the side wall of the top rod 412. A third limiting groove is formed on the side wall of the groove 411 along the sliding direction of the top rod 412. The third limiting block is slidably disposed in the third limiting groove. A first friction surface is provided on the end of the top block 41 near the shoe plate 33. A second friction surface is provided on the end of the shoe plate 33 near the top block 41.

[0050] Reference Figure 5 The top block 41 is provided with a third elastic element 413 for driving the top rod 412 to slide away from the top block 41. The third elastic element 413 includes a support spring. The bottom wall of the slide groove 411 is provided with a placement groove 414 communicating with the slide groove 411 along the length direction of the top rod 412. The support spring is disposed in the placement groove 414. One end of the support spring abuts against the bottom wall of the placement groove 414, and the other end of the support spring abuts against the top rod 412. The second driving member 42 includes a servo hydraulic cylinder. A fixing frame is fixedly provided on the side wall of the brake shoe 3. The servo hydraulic cylinder is fixedly disposed on the fixing frame. The piston rod of the servo hydraulic cylinder is fixedly connected to the top rod 412.

[0051] The servo hydraulic cylinder drives the push rod 412 to slide closer to the shoe plate 33, so that the first friction surface on the push block 41 is pressed against the second friction surface on the shoe plate 33. A sufficiently large static friction force is generated between the push block 41 and the shoe plate 33, thereby preventing the shoe plate 33 from sliding on the brake shoe 3. In addition, the support spring is set in the placement groove 414, which to a certain extent prevents the support spring from being crushed.

[0052] Reference Figure 4 , 5 A positioning plate 35 is slidably disposed on the brake shoe 3 along the length direction of the push rod 412. A transmission component for driving the positioning plate 35 to slide is provided on the brake shoe 3. The transmission component includes a transmission rod 36. One end of the transmission rod 36 is fixedly connected to the push rod 412. The transmission rod 36 extends to the side of the brake shoe 3 away from the hydraulic cylinder. A long groove 361 is opened on the side of the transmission rod 36 away from the hydraulic cylinder along the sliding direction of the shoe plate 33. A slider 362 is slidably disposed in the long groove 361. The positioning plate 35 is fixedly disposed on the slider 362.

[0053] Reference Figure 4The transmission rod 36 is provided with a limiting component to prevent the slider 362 from sliding. The limiting component includes a limiting screw 363, which is rotatably mounted on the transmission rod 36. The axial direction of the limiting screw 363 is parallel to the sliding direction of the slider 362. One end of the limiting rod extends into the elongated groove 361, and the limiting screw 363 is threadedly engaged with the slider 362.

[0054] By rotating the limiting screw 363, the slider 362 can be driven to slide within the elongated groove 361, adjusting the distance between the positioning plate 35 and the brake shoe 3. When the limiting screw 363 stops rotating, the slider 362 is prevented from sliding. This allows for adjustment of the brake response time according to actual needs, further increasing practicality. During braking, the push rod 412 slides towards the shoe plate 33, driving the positioning plate 35 to slide via the transmission rod 36. After the push block 41 slides a certain distance, the first... The friction surface abuts against the second friction surface on the shoe plate 33. Under the elastic force of the third elastic element 413, the top block 41 pre-presses the shoe plate 33. Then, the top rod 412 continues to slide. The top rod 412 slides in the groove 411 of the top block 41, which continues to make the positioning plate 35 slide, thereby causing the positioning plate 35 to separate from the friction plate 31. The double-acting hydraulic cylinder drives the brake shoe 3 to deflect towards the inner wall of the brake drum 2. The friction plate 31 squeezes the brake drum 2, and the brake drum 2 is decelerated by friction, thereby forcing the wheel to stop rotating.

[0055] Reference Figure 4 The positioning plate 35 has several spherical grooves at one end near the friction plate 31. Each spherical groove is provided with a ball, and one end of the ball extends out of the spherical groove and is used to roll and connect with the friction plate 31. When the friction plate 31 abuts against the positioning plate 35, the sliding of the positioning plate 35 will generate a certain amount of friction with the friction plate 31. Over time, the positioning plate 35 is prone to wear. The ball reduces the friction between the positioning plate 35 and the friction plate 31, thereby increasing the service life of the positioning plate 35.

[0056] The implementation principle of a parking brake shoe assembly for automobiles according to an embodiment of this application is as follows: When the vehicle is in motion, the shoe 33, under the elastic force of the second compression spring, causes the friction pad 31 to abut against the positioning plate 35. The positioning plate 35 controls the distance between the friction pad 31 and the inner wall of the brake drum 2. When braking is required, the servo hydraulic cylinder drives the push rod 412 to slide closer to the shoe 33. The push rod 412 drives the top block 41 to slide, and through the transmission rod 36, drives the positioning plate 35 to slide. After the top block 41 slides a certain distance, the top block 41... The first friction surface abuts against the second friction surface on the shoe plate 33. Under the elastic force of the support spring, the top block 41 pre-presses the shoe plate 33. Then, the top rod 412 continues to slide. The top rod 412 slides in the groove 411 of the top block 41, which continues to make the positioning plate 35 slide, thereby causing the positioning plate 35 to separate from the friction plate 31. The double-acting hydraulic cylinder drives the brake shoe 3 to deflect towards the inner wall of the brake drum 2. The friction plate 31 squeezes the brake drum 2, and the brake drum 2 is decelerated by friction, thereby forcing the wheel to stop rotating.

[0057] After the double-acting hydraulic cylinder releases the force, the two brake shoes 3 deflect towards the double-acting hydraulic cylinder under the elastic force of the tension spring, and abut against the two piston rods of the double-acting hydraulic cylinder respectively. The servo hydraulic cylinder drives the push rod 412 to slide away from the shoe plate 33, causing the positioning plate 35 to slide to the travel path of the friction plate 31. After the baffle top block 41 disengages from the shoe plate 33, the friction plate 31 continues to abut against the positioning plate 35 under the elastic force of the second compression spring. This ensures that the distance between the friction plate 31 and the inner wall of the brake drum 2 remains consistent during each braking action, and the braking response time can be controlled within a relatively stable range, thereby greatly reducing the possibility of traffic accidents caused by untimely braking.

[0058] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A parking brake shoe assembly for automobiles, comprising a back plate (1) fixedly mounted on the vehicle body, and a brake drum (2) fixedly mounted on the vehicle wheel hub, characterized in that: A brake shoe (3) is rotatably mounted on the back plate (1). The brake shoe (3) is located inside the brake drum (2), and the brake shoe (3) deflects in a direction close to or away from the inner wall of the brake drum (2). A first driving member (11) is provided on the back plate (1) for driving the brake shoe (3) to deflect in a direction close to the inner wall of the brake drum (2). A first elastic member (12) is also provided on the back plate (1) for driving the brake shoe (3) to deflect in a direction away from the inner wall of the brake drum (2). A shoe plate (33) is slidably disposed on the brake shoe (3), a friction plate (31) is fixedly disposed on the shoe plate (33), a positioning plate (35) is slidably disposed on the brake shoe (3) along the axial direction of the brake drum (2), a transmission member for driving the positioning plate (35) to slide is disposed on the brake shoe (3), a second elastic member (34) for driving the shoe plate (33) to slide away from the brake shoe (3) is disposed on the brake shoe (3), and the friction plate (31) is used to abut against the positioning plate (35), and a limiting component (4) for preventing the shoe plate (33) from sliding is disposed on the brake shoe (3); The limiting component (4) includes a top block (41) and a second driving member (42). The top block (41) is slidably disposed on the brake shoe (3) in a direction close to or away from the side wall of the shoe plate (33). A first friction surface is provided at one end of the top block (41) close to the shoe plate (33), and a second friction surface is provided at one end of the shoe plate (33) close to the top block (41). The second driving member (42) is used to drive the top block (41) to slide. A fixing sleeve (13) is fixedly provided on the back plate (1), and a locking gear (131) is slidably provided on the fixing sleeve (13). The axial direction of the locking gear (131) coincides with the central axis of the brake drum (2). A toothed sleeve (21) is coaxially fixedly provided inside the brake drum (2). The toothed sleeve (21) is adapted to the locking gear (131). A third driving member (14) for driving the locking gear (131) to slide is provided on the back plate (1).

2. The automotive parking brake shoe assembly according to claim 1, characterized in that: The top block (41) has a groove (411) at one end away from the shoe plate (33). A top rod (412) is slidably arranged in the groove (411), and the length direction of the top rod (412) is parallel to the sliding direction of the top block (41). A third elastic element (413) is provided on the top block (41) for driving the top rod (412) to slide away from the top block (41). The second driving element (42) is used to drive the top rod (412) to slide. The transmission element includes a transmission rod (36). One end of the transmission rod (36) is fixedly connected to the top rod (412). The transmission rod (36) extends to the side of the brake shoe (3) away from the hydraulic cylinder. The positioning plate (35) is arranged on the transmission rod (36).

3. The automotive parking brake shoe assembly according to claim 2, characterized in that: The third elastic element (413) includes a support spring. The bottom wall of the slide (411) is provided with a placement groove (414) communicating with the slide (411) along the length direction of the top rod (412). The support spring is disposed in the placement groove (414).

4. The automotive parking brake shoe assembly according to claim 2, characterized in that: The transmission rod (36) has an elongated groove (361) along the direction close to or away from the brake shoe (3). A slider (362) is slidably disposed in the elongated groove (361). The positioning plate (35) is fixedly connected to the slider (362). The transmission rod (36) is provided with a limiting member to prevent the slider (362) from sliding.

5. The automotive parking brake shoe assembly according to claim 4, characterized in that: The limiting component includes a limiting screw (363), which is rotatably mounted on the transmission rod (36), and the axial direction of the limiting screw (363) is parallel to the sliding direction of the slider (362). The limiting screw (363) and the slider (362) are threadedly engaged.

6. The automotive parking brake shoe assembly according to claim 1, characterized in that: The positioning plate (35) has several spherical grooves at one end near the friction plate (31). Each spherical groove is provided with a ball, and one end of the ball extends out of the spherical groove and is used to roll and connect with the friction plate (31).

7. The automotive parking brake shoe assembly according to claim 1, characterized in that: The friction plate (31) is detachably mounted on the shoe plate (33), and the shoe plate (33) is provided with a fastener (331) for fixing the friction plate (31).

8. The automotive parking brake shoe assembly according to claim 1, characterized in that: A push ring (132) is slidably disposed on the fixed sleeve (13) along the axial direction of the locking gear (131). The push ring (132) is disposed between the locking gear (131) and the back plate (1). A fourth elastic element (133) is disposed on the push ring (132) for driving the locking gear (131) to slide away from the push ring (132). The third driving element (14) is used to drive the push ring (132) to slide.

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