CN103253254B - Automobile braking system - Google Patents

Abstract

The invention relates to an automobile braking system. A brake pedal is connected to a booster, and the booster is connected to a front wheel brake and a rear wheel brake through an oil pipe. The front wheel brake is a floating caliper disc brake, and the rear wheel brake is a drum brake. The combined use of disc brakes and drum brakes ensures that the car has a good braking effect, minimizes the damage to the car during the braking process, and prolongs the service life of the car. The brake disc of the floating caliper disc brake is arranged between the first friction pad and the second friction pad, the surface of the first friction pad close to the brake disc is provided with several pad grooves, and the second friction pad The surface of the block close to the brake disc is provided with a raised line, and the section of the raised line is in a convex arc shape, and the surface opposite to the brake disc and the second friction pad is provided with an annular groove matching the raised line, and the section of the annular groove is It is concave arc-shaped; the groove of the pad is arc-shaped, and the center of the groove of the arc-shaped pad is on the axis of the brake disc; there are several radial bars on the opposite surface of the brake disc and the first friction pad The groove of the moving disk and the outer wall of the brake disk are radially provided with several cooling holes.

Description

car brake system

technical field

The present invention relates to a kind of braking device, more specifically, it relates to a kind of automobile braking system with good braking performance. the

Background technique

The braking system of a car is an important part of the car. The performance of the braking system directly affects the driving safety of the car. At present, most cars use disc brakes or drum brakes. When disc brakes are in use, the braking speed Fast, quickly reach a greater braking friction, this braking method has a greater impact on the performance of the car, the brake is prone to lock-up, and the friction lining and brake disc are easy to wear. The drum brake uses the pistons on both sides of the wheel cylinder to drive the brake shoe to move to achieve braking. When the resistance encountered by the two pistons is different, the oil pressure pushes the two pistons. The two pistons move at different speeds, and the synchronization of the movement is poor, so that they are respectively The synchronization of the movement of the two brake shoes connected with the two pistons is poor, which greatly affects the braking effect of the drum brake.

Chinese Patent Publication No. CN1563734A discloses a disc brake for automobiles. The two piston groups in the hydraulic cylinder of the disc brake are connected by bolts to steel pads, springs, short pistons and long pistons. In the oil seal groove of the short piston, the L-shaped or C-shaped oil seal is in the oil seal groove of the long piston. When braking, the two piston groups slide to both sides of the hydraulic cylinder, so that the two friction plates of the brake disc are quickly attached to the brake disc, and the brake disc is braked by friction. To achieve greater braking friction, this braking method has a greater impact on the performance of the car, the brake is prone to lock-up, and the friction plates and brake discs are easy to wear. Another example is the Chinese Patent Publication No. CN102312944A, which discloses a drum brake comprising a brake drum, a first brake shoe, a second brake shoe, and two ends respectively hooked on the first brake shoe and the second brake shoe. The return spring on the top and the gap self-adjusting mechanism connected between the first brake shoe and the second brake shoe. The gap self-adjusting mechanism includes a screw sleeve, a screw and a pivoting carrier. The first section of the screw has an external thread , the screw sleeve has an internal thread, the external thread and the internal thread form a self-locking thread pair, the internal thread and the external thread are clearance fit, the second section of the screw is pivotally connected with the pivot carrier, and the clearance self-adjusting mechanism also includes the screw The push part that the sleeve and the screw rod are away from each other. The pistons at both ends of the drum brake wheel cylinder have different resistances when sliding, which leads to poor synchronization of the movement of the two brake shoes connected to the two pistons, which greatly affects the braking effect of the drum brake.

Contents of the invention

The present invention overcomes the deficiencies in the following three aspects: the first is that the comprehensive performance of the automobile braking system is not ideal enough, and the braking effect is poor; Dynamic friction has a great impact on the performance of the car, and the brakes are prone to lockup, and the friction plates and brake discs are easy to wear; the third is that the pistons at both ends of the drum brake wheel cylinder have different resistances when sliding. In this case, the synchronization of the movement of the two brake shoes connected with the two pistons is poor, which greatly affects the braking effect of the drum brake. The invention provides an automobile braking system, which has ideal comprehensive performance and good braking effect. When the disc brake is in use, the friction between the friction plate and the brake disc increases gradually instead of rapidly, which reduces the damage to the car during the braking process and reduces the wear of the friction plate and the brake disc. The brake is not easy to lock, which prolongs the service life of the brake. The two brake shoes of the drum brake have good synchronization when braking, which ensures that the brake drum has a better braking effect. The combined use of disc brakes and drum brakes ensures that the car has a good braking effect on the one hand, and on the other hand minimizes the damage to the car during the braking process and prolongs the service life of the car.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a vehicle braking system, including a brake pedal, the brake pedal is connected to a booster, the booster is connected to the front wheel brake and the rear wheel brake through the oil pipe, and the front wheel brake is a floating Caliper disc brakes, rear drum brakes.

In the automobile braking system, the front wheels are braked by floating caliper disc brakes, and the rear wheels are braked by drum brakes. The floating caliper disc brakes have good heat dissipation performance and wading performance, and good braking stability. Drum brakes can achieve high braking efficiency factor and large braking force. The automobile braking system comprehensively utilizes floating caliper disc brakes and drum brakes, and the overall performance of automobile braking is ideal and the braking effect is good.

Preferably, the floating caliper disc brake includes a brake disc and a brake caliper, and a cavity is provided in the brake caliper, and the cavity includes an oil cavity and a brake disc accommodation cavity, and the brake disc accommodation cavity is radially inserted into the brake disc. On the brake caliper, there is an oil inlet hole communicating with the oil chamber, and a piston is arranged in the oil chamber, the end of the piston is fixedly connected to the first friction pad, and the inner wall of the brake disc accommodation chamber and the piston is fixedly connected to the second pad. Two friction pads, the brake disc is arranged between the first friction pad and the second friction pad, the surface of the first friction pad close to the brake disc is provided with several pad grooves, the second friction pad The surface close to the brake disc is provided with a raised line, the section of the raised line is in a convex arc shape, and the surface opposite to the brake disc and the second friction pad is provided with an annular groove adapted to the raised line, and the section of the annular groove is Concave arc.

When the brake of this structure is braking, the brake pedal is stepped on, the oil is delivered from the oil inlet hole to the oil chamber, and the high-pressure oil pushes the piston to move, and the movement of the piston pushes the first friction pad against the brake disc. , when the first friction pad is attached to the brake disc, the piston continues to move, so that the brake caliper moves in the opposite direction to the movement of the piston, and the second friction pad is also attached to the brake disc. Both the first friction pad and the second friction pad are attached to the brake disc to realize braking. The braking process is that the first friction pad and the brake disc are attached to brake first. Since the first friction pad is provided with several pad grooves on the surface that is attached to the brake disc, the first friction pad is reduced. The bonding area between the friction pad and the brake disc reduces the braking force, and the friction debris generated by the friction between the first friction pad and the brake disc can be collected in the groove of the pad to prevent the friction debris from being trapped in the first friction lining. between the pad and the surface of the brake disc to accelerate the wear of the first friction pad and the brake disc. The surface of the second friction pad is provided with arc-shaped convex strips, which are adapted to the annular grooves on the brake disc. When braking, the surfaces of the convex strips are attached to the bottom surface of the annular grooves. The joint surface is arc-shaped, rather than plane joint, which increases the joint area, thereby increasing the braking force. When the floating caliper disc brake brakes, first the first friction pad and the brake disc are applied to brake, and the braking force is small, and then the second friction pad is attached to the brake disc to brake, and the braking force is large. When the brake disc brakes, the braking friction force gradually increases instead of rapidly increasing, which reduces the damage to the car during the braking process, reduces the wear of the friction pads and the brake disc, and prevents the brake from clogging. dead phenomenon, prolonging the service life of the brake.

Preferably, the pad groove is arc-shaped, and the center of the arc-shaped pad groove is on the axis of the brake disc. This structure ensures that the groove of the pad is consistent with the contour of the brake disc during rotation, reducing the wear of the groove of the pad on the edge of the notch.

Preferably, a plurality of brake disc grooves are radially provided on the opposite surface of the brake disc and the first friction pad, and a plurality of cooling holes are radially provided on the outer wall of the brake disc. The groove of the brake disc is arranged on the surface where the brake disc and the first friction pad are attached, and the friction force is appropriately reduced when the first friction pad is attached to the brake disc at the initial stage of braking. , to prevent the phenomenon of locking due to excessive friction.

Preferably, the brake caliper is provided with an air release hole communicating with the oil chamber, and an air release screw is connected to the air release hole. The setting of the vent hole facilitates the discharge of gas in the oil chamber, so that the oil in the oil chamber will not contain air bubbles.

As a preference, the end of the piston is fixedly connected to the first back plate, a first sound-absorbing sheet is arranged between the first back plate and the piston, and the first friction pad is fixedly connected to the first back plate; the brake disc accommodation chamber is opposite to the piston The second back plate is fixedly connected to the inner wall of the inner wall of the brake disc, the second sound-absorbing sheet is fixedly connected between the second back plate and the inner wall of the brake disc accommodation cavity, and the second friction pad is fixedly connected to the second back plate. Frictional braking between the friction lining and the brake disc will generate noise, which is effectively prevented from being transmitted to the vehicle body through the absorption of the first and second sound-absorbing sheets.

Preferably, the drum brake includes a brake drum, a brake shoe, a friction plate connected to the brake shoe, a support seat, and a wheel cylinder. One end of the two brake shoes is hinged on the support seat, and the other end of the two brake shoes All are hinged with a connecting rod that is arranged at an inclination, and a wheel cylinder piston is arranged in the wheel cylinder, and a hinge plate is connected on the wheel cylinder piston.

The movement of the wheel cylinder piston promotes the movement of the two connecting rods hinged on the hinge plate, and the two connecting rods expand outward to push the two brake shoes to move outward, so that the friction plate and the inner wall of the brake drum are attached to realize friction braking. The two connecting rods are hinged together on the hinge plate. When the piston is moving, the magnitude and direction of the force on the two connecting rods are the same, and the two connecting rods and the two brake shoes are symmetrically arranged, so the two brake shoes The synchronization is good when moving, which ensures that the brake drum has a better braking effect.

Preferably, a return spring is connected between the two brake shoes. A return spring is arranged between the two brake shoes. When the brake pedal is released, the two brake shoes are drawn towards the middle by the elastic action of the return spring, so that the two pull rods are drawn together and the piston is pushed back. The structure is simple.

As a preference, a boss is provided on the inner end surface of the wheel cylinder piston, a limit ring is provided at the connection position between the boss and the end surface of the wheel cylinder piston, a limit friction ring is provided in the limit ring, and a ring is provided on the inner wall of the wheel cylinder piston near the boss. The edge of the convex edge, the edge of the upper end surface of the limit friction ring is attached to the lower end surface of the convex edge; the outer wall of the wheel cylinder piston is provided with a sealing ring, and there are two sealing rings inside the sealing ring, and the two sealing rings are respectively attached to the sides of the sealing ring. There is a gap between the two sealing rings on the two side walls; a flexible dust cover is connected to the outer end surface of the wheel cylinder piston, and the dust cover is sleeved on the end of the wheel cylinder. A limit friction ring is set in the limit ring at the connection position between the wheel cylinder piston and the boss. After the wheel cylinder piston returns, the edge of the upper end surface of the limit friction ring fits on the lower end surface of the convex edge to prevent the wheel cylinder piston from returning. excess. Two sealing rings are arranged in the sealing ring to form a two-layer sealing structure, and the sealing performance is good. The dust cover prevents foreign matter from falling into the wheel cylinder, ensuring the safe and smooth operation of the wheel cylinder.

Preferably, a slot is provided at the hinged end of the connecting rod and the brake shoe, and the slot is arranged on the connecting rod so that the end of the connecting rod is U-shaped, and the brake shoe is hinged in the slot; There are two hinged lugs at the end, one hinged lug is close to the side of the connecting rod, the other is close to the middle of the end face of the connecting rod, the hinged lugs on the two connecting rods are interleavedly inserted together and hinged on the hinge plate. The two connecting rods are hinged between the hinge plate and the brake shoe in this way, and the force is more stable, which further ensures the synchronization of the two brake shoes.

Compared with the prior art, the beneficial effects of the present invention are: (1) the comprehensive performance of the automobile braking system is ideal, and the braking effect is good; The friction force increases gradually instead of rapidly, which reduces the damage to the car during the braking process, reduces the wear of the friction plate and the brake disc, prevents the brake from locking up, and prolongs the service life of the brake; ( 3) The two brake shoes of the drum brake have good synchronization when braking, which ensures that the brake drum has a better braking effect; (4) The combined use of the disc brake and the drum brake ensures that the vehicle It has a good braking effect, and on the other hand, it minimizes the damage to the car during the braking process and prolongs the service life of the car.

Description of drawings

Fig. 1 is a kind of structural representation of the present invention;

Fig. 2 is a sectional view of the floating caliper disc brake of the present invention;

Fig. 3 is a sectional view of the drum brake of the present invention;

Fig. 4 is the sectional view of wheel cylinder of the present invention;

Fig. 5 is the sectional view of connecting rod hinge of the present invention;

Among the figure: 1, brake pedal, 2, booster, 3, floating caliper disc brake, 4, drum brake, 301, brake disc, 302, brake caliper, 303, oil cavity, 304 brake disc accommodates Cavity, 305, oil inlet hole, 306, piston, 307, first friction pad, 308, second friction pad, 309, pad groove, 310, convex strip, 311, annular groove, 312, brake disc Groove, 313, heat dissipation hole, 314, vent hole, 315, vent screw, 316, the first backboard, 317, the first sound-absorbing sheet, 318, the second backboard, 319, the second sound-absorbing sheet, 401, manufacture Moving drum, 402, brake shoe, 403, friction plate, 404, support seat, 405, wheel cylinder, 406, connecting rod, 407, wheel cylinder piston, 408, hinge plate, 409, return spring, 410, boss , 411, limit ring, 412, limit friction ring, 413, seal ring, 414, seal ring, 415, dust cover, 416, slot, 417, hinged ear, 418, convex edge.

Detailed ways

Below by specific embodiment, in conjunction with accompanying drawing, the technical solution of the present invention is described in further detail:

Embodiment: A kind of automobile brake system (see accompanying drawing 1), comprises brake pedal 1, and brake pedal 1 is connected with booster 2, and booster 2 is connected front wheel brake and rear wheel brake through oil pipe, and front wheel brake is floating Caliper disc brake 3, rear wheel brake is drum brake 4. The oil pipe between the rear wheel brake and the booster 2 is connected with an inertia proportional valve.

The floating caliper disc brake 3 (see accompanying drawing 2) includes a brake disc 301 and a brake caliper 302. There is a cavity inside the brake caliper 302. The cavity includes an oil cavity 303 and a brake disc accommodation cavity 304. The brake disc The accommodating chamber 304 is radially inserted on the brake disc 301, the brake caliper 302 is provided with an oil inlet hole 305 communicating with the oil chamber 303, and the oil chamber 303 is provided with a piston 306, the piston 306 is in the shape of a barrel, the shape of a barrel The barrel bottom of the piston 306 faces the oil inlet hole 305 , and the axis of the oil inlet hole 305 coincides with the axis of the oil chamber 303 . The brake caliper 302 is provided with an air release hole 314 communicating with the oil chamber 303, the angle between the axis of the air release hole 314 and the axis of the oil chamber 303 is an acute angle, and the air release hole 314 and the oil inlet hole 305 are arranged at the same on the side. An air release screw 315 is tightly connected to the air release hole 314 . The end of the opening of the piston 306 is fixedly connected to the first friction pad 307, and the inner wall of the brake disc accommodation cavity 304 and the opposite inner wall of the piston 306 is fixedly connected to the second friction pad 308, and the brake disc 301 is arranged on the first friction pad 307 and between the second friction pads 308 . The end of the piston 306 is fixedly connected to the first back plate 316, and a first noise reduction plate 317 is arranged between the first back plate 316 and the piston 306, and the first friction pad 307 is fixedly connected to the first back plate 316, and the brake disc accommodates The inner wall opposite to the chamber 304 and the piston 306 is fixedly connected to the second back plate 318, and the second back plate 318 is fixedly connected to the inner wall of the brake disc accommodation cavity 304. On the second backplane 318 . Eight pad grooves 309 are arranged on the surface of the first friction pad 307 close to the brake disc 301 . A plurality of brake disc grooves 312 are radially provided on the opposite surface of the brake disc 301 and the first friction pad 307 , and a plurality of cooling holes 313 are radially provided on the outer wall of the brake disc 301 . The surface of the second friction pad 308 close to the brake disc 301 is provided with a convex strip 310 , and the cross section of the convex strip 310 is in an outwardly convex arc shape. Both the upper edge contour and the lower edge contour of the convex strip 310 are arc-shaped, and the center of the arc contour is on the axis of the brake disc 301 . On the opposite surface of the brake disc 301 and the second friction pad 308, there is an annular groove 311 adapted to the convex strip 310. The circular shape of the annular groove 311 is on the axis of the brake disc 301, and the cross section of the annular groove 311 is concave. arc.

The drum brake 4 (see accompanying drawing 3) comprises a brake drum 401, a brake shoe 402, a friction plate 403 connected to the brake shoe 402, a support seat 404, and a wheel cylinder 405, and the support seat 404 and the wheel cylinder 405 are fixed Attached to the brake back plate. The friction plate 403 is arranged on the outer surface of the brake shoe 402 . One ends of the two brake shoes 402 are hinged on the support base 404, and the other ends of the two brake shoes 402 are hinged to a connecting rod 406 arranged at an angle. The wheel cylinder 405 is provided with a wheel cylinder piston 407 connected to the wheel cylinder piston 407. The hinge plate 408 and the two connecting rods 406 are hinged on the hinge plate 408 together, and the two connecting rods 406 and the two brake shoes 402 are arranged symmetrically. A return spring 409 is connected between the two brake shoes 402, and the connection position of the return spring 409 is close to the hinged position of the connecting rod 406 and the brake shoe 402 and is below the hinged position. The hinged end of the connecting rod 406 and the brake shoe 402 is provided with a slot 416 (see Figure 5), the slot 416 is arranged on the connecting rod 406 so that the end of the connecting rod 406 is U-shaped, and the brake shoe 402 passes through the hinge shaft Hinged in slot 416. The hinged end of the connecting rod 406 and the hinged plate 408 is provided with two hinged ears 417, one hinged ear 417 is close to the side of the connecting rod 406, and the other hinged ear 417 is close to the middle position of the end face of the connecting rod 406. On the two connecting rods 406 The hinge lugs 417 are interleavedly inserted together and hinged on the hinge plate 408, and the connecting rod 406 and the hinge plate 408 are hinged together through the hinge shaft. The inner end surface of the wheel cylinder piston 407 is provided with a cylindrical boss 410 (see accompanying drawing 4). The diameter of the boss 410 is smaller than the diameter of the wheel cylinder piston 407. A limit friction ring 412 is provided in the position ring 411 , and an annular convex edge 418 is provided on the inner wall of the wheel cylinder piston 407 close to the boss 410 . There is a seal ring 413 on the outer wall of the wheel cylinder piston 407, and there are two seal rings 414 inside the seal ring 413. , the outer end surface of the wheel cylinder piston 407 is connected with a flexible dust cover 415 , and the dust cover 415 is sleeved on the end of the wheel cylinder 405 . The hinge plate is fastened on the wheel cylinder piston 407 by screw connection.

In the car braking system, the front wheels are braked by floating caliper disc brakes, and the rear wheels are braked by drum brakes. When the brake pedal is depressed, fluid flows to the floating caliper disc brakes and drum brakes for simultaneous braking. The oil is delivered from the oil inlet hole of the front wheel floating caliper disc brake to the oil chamber, the high-pressure oil pushes the piston to move, and the movement of the piston pushes the first friction pad to lean against the brake disc. When the first friction pad and the brake After the disc is attached, the piston continues to move, so that the brake caliper moves in the direction opposite to that of the piston, and the second friction pad is also attached to the brake disc. Both the first friction pad and the second friction pad are attached to the brake disc to realize braking. The braking process is that the first friction pad and the brake disc are attached to brake first. Since the first friction pad is provided with several pad grooves on the surface that is attached to the brake disc, the first friction pad is reduced. The bonding area between the friction pad and the brake disc reduces the braking force, and the friction debris generated by the friction between the first friction pad and the brake disc can be collected in the groove of the pad to prevent the friction debris from being trapped in the first friction lining. between the pad and the surface of the brake disc to accelerate the wear of the first friction pad and the brake disc. The surface of the second friction pad is provided with arc-shaped convex strips, which are adapted to the annular grooves on the brake disc. When braking, the surfaces of the convex strips are attached to the bottom surface of the annular grooves. The joint surface is arc-shaped, rather than plane joint, which increases the joint area, thereby increasing the braking force. When the floating caliper disc brake brakes, first the first friction pad and the brake disc are applied to brake, and the braking force is small, and then the second friction pad is attached to the brake disc to brake, and the braking force is large. When the brake disc brakes, the braking friction force gradually increases instead of rapidly increasing, which reduces the damage to the car during the braking process, reduces the wear of the friction pads and the brake disc, and prevents the brake from clogging. dead phenomenon, prolonging the service life of the brake. At the same time, the oil flows into the cavity of the wheel cylinder, the movement of the wheel cylinder piston pushes the movement of the two connecting rods hinged on the hinge plate, and the two connecting rods expand outwards to push the two brake shoes to move outwards, so that the friction plate and the The inner wall of the dynamic drum is bonded to realize friction braking. The two connecting rods are hinged together on the hinge plate. When the piston is moving, the magnitude and direction of the force on the two connecting rods are the same, and the two connecting rods and the two brake shoes are symmetrically arranged, so the two brake shoes The synchronization is good when moving, which ensures that the brake drum has a better braking effect.

The embodiment described above is only a preferred solution of the present invention, and does not limit the present invention in any form. There are other variations and modifications on the premise of not exceeding the technical solution described in the claims.

Claims (7)

1. a brake system of car, comprise brake pedal (1), brake pedal connects servo-unit (2), servo-unit connects front-wheel brake and rear wheel brake by oil pipe, it is characterized in that, front-wheel brake is floating caliper brake (3), and rear wheel brake is drum brake mechanism (4), floating caliper brake comprises brake disc (301), brake clamp (302), cavity is provided with in brake clamp, cavity comprises oil pocket (303) and brake disc container cavity (304), brake disc container cavity radial direction is inserted on the disc brake rotor, brake clamp is provided with the fuel feed hole (305) be communicated with oil pocket, piston (306) is provided with in oil pocket, the end winding support of piston connects the first lining pad (307), the inwall that brake disc container cavity is relative with piston is fixedly connected with the second lining pad (308), brake disc is arranged between the first lining pad and the second lining pad, first lining pad is provided with some pad grooves (309) near the surface of brake disc, second lining pad is provided with raised line (310) near the surface of brake disc, the cross section of raised line is the arc of evagination, the surface that brake disc is relative with the second lining pad is provided with and the circular groove of raised line adaptation (311), circular groove cross section is indent arc, pad groove is curved, and the center of circle of arc pad groove is on the axis of brake disc, on the surface that brake disc is relative with the first lining pad, radial direction is provided with some brake disc grooves (312), and on brake disc lateral wall, radial direction is provided with several louvres (313).

2. brake system of car according to claim 1, is characterized in that, brake clamp is provided with the air bleed hole (314) be communicated with oil pocket, air bleed hole is connected with air bleed screw (315).

3. brake system of car according to claim 1, is characterized in that, pistons end is fixedly connected with the first backboard (316), is provided with the first bloop (317) between the first backboard and piston, and the first lining pad is fixedly connected on the first backboard; The inwall that brake disc container cavity is relative with piston is fixedly connected with the second backboard (318), and be fixedly connected with the second bloop (319) between the second backboard and brake disc container cavity inwall, the second lining pad is fixedly connected on the second backboard.

4. brake system of car according to claim 1, it is characterized in that, drum brake mechanism comprises brake wheel (401), brake shoe brake cheek (402), the friction lining (403) be connected on brake shoe brake cheek, supporting seat (404), wheel cylinder (405), two brake shoe brake cheek one end are all hinged on supporting seat, the all hinged connecting rod be obliquely installed (406) of the other end of two brake shoe brake cheek, wheelcylinder piston (407) is provided with in wheel cylinder, connecting hinge fishplate bar (408) on wheelcylinder piston, two connecting rods are hinged on articulated slab together, and two connecting rods and two brake shoe brake cheek are all symmetrical arranged.

5. brake system of car according to claim 4, is characterized in that, is connected with pull back spring (409) between two brake shoe brake cheek.

6. brake system of car according to claim 4, it is characterized in that, the inner end surface of wheelcylinder piston is provided with boss (410), boss and wheelcylinder piston end face connection location are provided with spacing ring (411), limit friction ring (412) is provided with in spacing ring, wheelcylinder piston inwall is provided with convex annular along (418) near lug boss position, and edge, limit friction ring upper surface is fitted on the lower surface of convex edge; Wheelcylinder piston outer wall is provided with seal ring (413), and be provided with two seal rings (414) in seal ring, two seal rings are fitted on the two side of seal ring respectively, are provided with gap between two seal rings; The outer face of wheelcylinder piston is connected with flexible dustproof cover (415), dust boot is socketed in the end of wheel cylinder.

7. brake system of car according to claim 5, is characterized in that, connecting rod and the hinged end of brake shoe brake cheek are provided with slot (416), and slot is arranged on connecting rod and interlinking lever end is taken the shape of the letter U, and brake shoe brake cheek is hinged in slot; Connecting rod and the hinged end of articulated slab are provided with two hinged ears (417), and hinged ear is near the lateral location of connecting rod, and another hinged ear is near connecting rod end face midway location, and the hinged ear on two connecting rods is staggered to be plugged in together and to be hinged on articulated slab.