CN214304584U

CN214304584U - Low-pressure accumulator and vehicle brake system

Info

Publication number: CN214304584U
Application number: CN202023235348.9U
Authority: CN
Inventors: 胡亚; 江海
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2021-09-28
Anticipated expiration: 2030-12-29

Abstract

The utility model provides a low pressure energy storage ware and vehicle braking system. The low pressure accumulator comprises: a cylinder body having an inner space, one end of the cylinder body in an axial direction having a brake fluid passage and an end cap provided at the other end of the cylinder body; the piston is accommodated in the inner space in a reciprocating manner between two ends of the cylinder body, the piston divides the inner space into a first space and a second space which are not communicated with each other, and the brake fluid channel is communicated with the first space; a venting device having a pressure compensation membrane is formed through the end cap and connects the second space in a gas-permeable manner to the environment. The gas communication between the inner space of the low-pressure accumulator and the external environment is realized through the ventilation device so as to keep the pressure balance between the inner space and the external environment. The venting device has good air permeability and can effectively prevent liquid/gaseous media in the external environment from entering the inner space of the low-pressure accumulator.

Description

Low-pressure accumulator and vehicle brake system

Technical Field

The present application relates to the field of vehicle braking, and in particular to a low pressure accumulator for a vehicle braking system and a vehicle braking system including such a low pressure accumulator.

Background

A braking system is installed in the vehicle to provide safety braking for the vehicle. A brake system of a vehicle generally includes a master cylinder and a brake circuit. The brake master cylinder receives a thrust force caused by operating a brake pedal of the vehicle and amplified by the booster to supply the brake fluid stored in the fluid reservoir to the brake circuit to generate a brake pressure. The brake circuit includes hydraulic components such as solenoid-operated valves, low-pressure accumulators, and pumps to achieve and control the brake pressure transmitted to the hydraulic brakes at the front and rear wheels. A low pressure accumulator is an energy storage device in the brake circuit that is filled with brake fluid to store energy in the system or drained of brake fluid to release energy as needed.

The low-pressure energy accumulator of the prior scheme comprises a cylinder body and a piston which reciprocates in the cylinder body, wherein one end of the cylinder body is provided with a liquid inlet and a liquid outlet, the other end of the cylinder body is provided with a ventilation device, the ventilation device is provided with a ventilation opening and a pressure balancing element, the ventilation opening penetrates through an end cover, and the ventilation opening can realize bidirectional ventilation between the internal space of the cylinder body and the environment outside the cylinder body so as to keep the internal space of the cylinder body at reasonable pressure; the pressure equalization element is fixed on the end cap and covers or partially covers the vent opening, and the pressure equalization element is a porous filter body made of foamed and/or sintered material and used for preventing gaseous and/or liquid medium permeating into the vent opening from entering into the inner space of the cylinder body. However, in some harsh usage scenarios, the existing balancing element still cannot completely prevent, for example, a liquid medium from entering the internal space of the cylinder, which tends to accelerate the aging of the piston and also to corrode the internal surface area of the cylinder, thereby affecting the performance of the low pressure accumulator. Furthermore, the liquid medium entering the interior of the cylinder also influences the amount of brake fluid that can be accommodated by the accumulator.

Therefore, there is a need to provide an improved technical solution to overcome the technical problems in the prior art.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the problem of poor sealing performance of the ventilating device of the low-pressure energy accumulator.

Therefore, the utility model is realized by the following scheme: there is provided a low pressure accumulator for a vehicle braking system comprising:

a cylinder having an inner space, one end of the cylinder in an axial direction having a brake fluid passage and an end cap provided at the other end of the cylinder;

the piston is accommodated in the inner space in a reciprocating manner between two ends of the cylinder body, the piston divides the inner space into a first space and a second space which are not communicated with each other, and the brake fluid channel is communicated with the first space;

a vent having a pressure balancing membrane, the vent configured penetratingly on the end cap and air-permeable communicating the second space with an ambient environment.

Further, the brake fluid channel comprises a fluid inlet and a fluid outlet which penetrate through the cylinder body, the piston is provided with a first end close to the brake fluid channel and a second end facing the end cover, the second end defines an accommodating space with an opening facing the end cover, the low-pressure accumulator comprises a spring, one end of the spring abuts against the closed inner end of the accommodating space, and the other end of the spring abuts against the end cover; when brake fluid entering the first space from the fluid inlet acts on the first end of the piston, the piston compresses the spring and moves towards the end cap; when brake fluid flows out of the fluid outlet, the spring is gradually reset, so that the piston moves in a direction away from the end cover.

Further, the low pressure accumulator comprises: the guide rings are respectively fixed on the piston in an embedded mode at two ends of the piston and are used for guiding the piston to reciprocate between two ends of the cylinder body; a first seal circumferentially disposed between the piston and the inner surface of the cylinder, the guide ring and the first seal both sliding reciprocally against the inner surface of the cylinder as the piston reciprocates between the two ends of the cylinder.

Further, the end cover has a through opening that runs through the end cover, the through opening intercommunication the second space with external environment, have on the end cover around the protruding edge axial direction of through opening to the wall that the second space extends, form installation space in the wall, pressure balance membrane install in the installation space, pressure balance membrane covers the through opening.

Further, the aeration device comprises a pressure balance membrane assembly which comprises a support and a pressure balance membrane supported by the support, wherein the support is provided with a base in an annular shape and an upper side wall which is raised from the upper surface of the base and continuously distributed along the circumferential direction of the base, the pressure balance membrane is carried by the base and is fixed in a space formed by the upper side wall in a surrounding mode, the support is also provided with a lower side wall which is raised from the lower surface of the base and continuously distributed along the circumferential direction of the base, and the lower side wall is positioned on the inner side of the upper side wall in the radial direction; the inner surface of the wall is provided with second steps distributed along the circumferential direction, and the lower surface of the base abuts against the second steps when the pressure balance membrane assembly is installed in the installation space.

Further, the air vent device includes a second seal member circumferentially surrounding the lower side wall, the inner surface of the wall has third steps distributed circumferentially thereon, the third steps are located on a side of the second steps toward the second end of the piston, the third steps narrow in a radial direction relative to the second steps within the mounting space, the second seal member is disposed between the lower side wall and the inner surface of the wall when the pressure-balanced membrane assembly is mounted in the mounting space, and the second seal member is pressed against the third steps by the lower surface.

Further, the length of the second seal in the axial direction is larger than the distance between the second step portion and the third step portion.

Further, the air vent device comprises a top cover, the top cover is provided with a plurality of openings penetrating through the top cover, first step portions distributed along the circumferential direction are arranged on the inner surface of the wall, the first step portions are located on one side, facing away from the second end of the piston, of the second step portions, the second step portions are narrowed in the radial direction relative to the first step portions in the installation space, and the top cover is installed at the openings and abuts against the first step portions and presses against the end face of the upper side wall so as to cover the pressure balance film.

Further, when the top cover is installed at the through hole, the edge of the top cover is in interference fit with the inner surface of the wall, so that the top cover is fixed in the installation space.

The present application further provides a vehicle braking system including a low pressure accumulator as defined in any one of the preceding claims.

As can be seen from the above, the low pressure accumulator of the embodiments of the present application employs the venting means having the pressure balancing membrane to achieve gas communication between the internal space of the low pressure accumulator, particularly the second space housing the piston, and the external environment so as to maintain pressure equalization therebetween. The ventilation device is hermetically installed at the through hole of the end cover through the matching of the top cover, the pressure balance membrane assembly, the second sealing piece and the step part which is formed on the inner surface of the wall and distributed in a trapezoidal shape. The venting device has good air permeability and can effectively prevent liquid/gaseous media in the external environment from entering the inner space of the low-pressure accumulator, so that the normal work of the low-pressure accumulator is influenced.

Drawings

The features, characteristics, advantages and benefits of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

Fig. 1 is a cross-sectional view of a low pressure accumulator for a vehicle braking system according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an exploded structure of the breather of FIG. 1;

FIG. 3 is a cross-sectional view of the end cap of FIG. 1;

fig. 4 is a sectional view of a partial structure of the low pressure accumulator of fig. 1.

Detailed Description

The low pressure accumulator according to the present invention will be described in detail with reference to the accompanying drawings 1 to 3.

Fig. 1 is a sectional view showing a partial structure of a low pressure accumulator for a vehicle brake system according to the present embodiment. As shown, a cylinder 10 is shown, the cylinder 10 having an inner space R defined by an inner surface 11, and a brake fluid channel at one end of the cylinder 10 in an axial direction a, the brake fluid channel including an inlet port 12 and an outlet port 13 as shown. The cylinder 10 has an end cap 14 at the other end of the cylinder 10 in the axial direction a. The end cap 14 is provided with a venting device 15 which is formed through the end cap 14 and which communicates the interior R with the environment in a gas-permeable manner. Also shown in fig. 1 is a piston 20 housed in an internal space R of the cylinder 10 and reciprocally movable in the internal space R in the axial direction a.

An end of the piston 20 close to the liquid inlet 12 and the liquid outlet 13 of the cylinder 10 is referred to as a first end of the piston 20, and a second end opposite to the first end and facing the end cover 14 of the cylinder 10 is formed with a receiving space 25 facing the end cover 14 of the cylinder 10. The spring 30 is disposed between the second end of the piston 20 and the end cap 14 of the cylinder 10, one end of the spring 30 abuts against the closed inner end of the accommodating space 25, and the other end of the spring 30 abuts against the end cap 14.

Two

guide rings

21, 22 are fixed to the piston 20 in a flush manner near both ends of the piston 20, and the

guide rings

21, 22 serve to guide the piston 20 in a reciprocating motion in the axial direction a and abut against the inner surface 11 of the cylinder 10 when the piston 20 moves in the axial direction.

A first seal 23, which is fitted around the piston, is arranged between the two

guide rings

21, 22, the first seal 23 being arranged radially of the piston 20 between an outer surface 24 of the piston 20 and the inner surface 11 of the cylinder 10. The first seal 23 sealingly engages the inner surface 11 of the cylinder 10 during the entire axial stroke of the piston 20 to divide the internal space R of the cylinder 10 into a first space R1 and a second space R2 that are spaced apart in the axial direction a. The first seal 23 prevents the brake fluid, which enters the first space R1 from the inlet port 12, from entering the second space R2 through the gap between the outer surface 24 and the inner surface 11. Likewise, the first seal 23 also prevents liquid/gas medium that may enter the second space R2 from the venting device 15 from entering the first space R1 through the gap between the outer surface 24 and the inner surface 11.

In the present embodiment, the first seal 23 is embedded in a piston annular groove formed on the outer surface 21 of the piston 20 as shown in fig. 1, and the first seal 23 of an elastic material sealingly engages the inner surface 11 of the cylinder 10 toward the cylinder 10. However, it should be understood by those skilled in the art that in other embodiments, the first sealing member 23 may be embedded in a cylinder annular groove formed on the inner surface 11 of the cylinder 10, and the first sealing member 23 of the elastic material is engaged with the outer surface 21 of the piston 20 in a sealing manner toward the piston 20, in which case, since there is no need to provide an annular groove for embedding the sealing member on the outer surface of the piston 20, the outer contour structure of the piston 20 is more concise, the product design is simplified, and the dimensional accuracy in the production of the piston is easier to control, and the production efficiency and the yield are improved.

With continued reference to fig. 1, fig. 1 shows the piston 20 of the low-pressure accumulator in an initial position when the low-pressure accumulator is not filled with brake fluid. When the brake fluid enters the first space R1 through the inlet port 12, the brake fluid first acts on the first end of the piston 20 near the inlet port 12. When the urging force of the brake fluid against the piston 20 overcomes the elastic force of the spring 30, the piston 20 starts to compress the spring 30 and moves toward the end cap 14, whereby the volume of the second space R2 accommodating the spring 30 becomes smaller, and the volume of the first space R1 increases accordingly to accommodate the brake fluid. In contrast, when the brake fluid flows out from the brake fluid outlet 13, the spring 30 is gradually returned, the piston 20 moves in a direction away from the end cap 14 and the volume of the first space R1 decreases and the volume of the second space R2 increases. During the above-mentioned reciprocating movement of the piston 20, the reduction of the volume of the second space R2 without the provision of the venting means 15 is necessarily accompanied by an increase in the gas pressure in the second space R2, which on the one hand may cause the compressed gas to exert a pressure on the first seal 23, so that the compressed gas escapes from the second space R2 past the first seal 23 into the first space R1 filled with brake fluid, at which time the piston 20 returns to its initial position due to the continued return of the spring 30, at which time the volume of the second space R2 continues to increase, whereby a negative pressure is very easily formed in the second space R2. Such a pressure change in the second space R2 may negatively affect the reciprocating movement of the piston 20 and thus the function of the accumulator. To solve this problem, the end cap 14 is made of a metal material and has a through port 141 penetrating the end cap 14, the through port 141 communicates the second space R2 with the external environment, bi-directional ventilation between the internal space R of the cylinder 10 and the external environment of the cylinder is enabled to maintain a reasonable pressure in the internal space R of the cylinder 10, the problem of air pressure fluctuation in the second space R2 is solved, and the sealing effect of sealing the first space R1 and the second space R2 from each other by the first sealing member 23 is also improved. The venting device 15 is mounted at the port 141. Further, the end cap 14 has a wall 142 projecting around the through opening 141 and extending toward the second space R2 in the axial direction a on the inner surface thereof, a mounting space R3 is formed in the wall 142, and the mounting space R3 communicates with the second space R2. The pressure balance film 153 is installed in the installation space R3 and covers the cross section of the through hole 141. The pressure equalization membrane 153 serves to prevent the liquid/gaseous medium from entering the second space R2 through the port 141.

Referring to fig. 2 to 4, the breather device 15 in the present embodiment includes a top cover 155, a second seal member 154, and a pressure balance membrane assembly 151, which are sequentially installed on the installation space R3 toward the second end direction of the piston. Wherein, the pressure balance membrane assembly 151 comprises a bracket 152 and a pressure balance membrane 153 carried by the bracket 152, the whole bracket 152 is made of plastic material, and has a base 1521 in a ring shape and an upper side wall 1522 which is raised from the upper surface of the base 1521 and is continuously distributed along the circumference of the base 1521, and the pressure balance membrane 153 is carried by the base 1521 in a space formed by the upper side wall 1522. The pressure balance membrane 153 may be an elastic waterproof breathable membrane made of any elastic material, and in the present embodiment, the pressure balance membrane 153 is made of a polymer material such as polytetrafluoroethylene. The pressure balancing membrane 153 is ultrasonically welded to the base 1521. The bracket 152 further has a lower sidewall 1523 protruding from the lower surface of the base 1521 and continuously distributed along the circumferential direction of the base 1521, and the lower sidewall 1523 is located radially inside the upper sidewall 1522. The surface of the seat 1521 facing the second end of the piston is defined herein as the lower surface and the surface of the seat 1521 facing away from the second end of the piston is defined herein as the upper surface. Correspondingly, the upper sidewall 1522 extends from the upper surface of the seat 1521 in a direction away from the second end of the piston, while the lower sidewall 1523 extends from the lower surface of the seat 1521 in a direction towards the second end of the piston. Wall 142 has second circumferentially spaced steps 1422 on its inner surface, and the lower surface of base 1521 abuts against second steps 1422 when pressure balance diaphragm assembly 151 is installed in installation space R3.

A second seal 154 made of rubber material having elasticity circumferentially surrounds the lower side wall 1523. The wall 142 has third steps 1423 circumferentially distributed on the inner surface thereof, the third steps 1423 are located on the side of the second step 1422 facing the second end of the piston 20, the third steps 1423 narrow in the radial direction with respect to the second steps 1422 in the installation space R3, and the second seal 154 is disposed between the lower side wall 1523 and the inner surface of the wall 142 when the pressure balance diaphragm assembly 151 is installed in the installation space R3. And the second seal 154 is pressed against the third step 1423 by the lower surface of the seat 1521. Further, the length of the second seal 154 in the axial direction a is slightly larger than the distance between the second step part 1422 and the third step part 1423, so that when the lower surface of the base 1521 abuts against the second step part 1422, the second seal 154 is pressed against the third step part 1423 by the lower surface of the base 1521, at which time the second seal 154 is in a compressed elastic state, thereby improving the sealing effect, in particular preventing liquid/gaseous medium that may enter along the gap between the upper side wall 1522 of the bracket 152 and the inner surface of the wall 142 from continuing along the gap between the lower side wall 1523 of the bracket 152 and the inner surface of the wall 142 into the mounting space R3 and thus into the inner space R of the low pressure accumulator.

The top cover 155 made of a metal material has a plurality of openings 1551 penetrating the top cover 155, the wall 142 has a first step 1421 distributed circumferentially on the inner surface, the first step 1421 is located on the side of the second step 1422 facing away from the second end of the piston 20, the second step 1422 is narrowed in the radial direction with respect to the first step 1421 in the installation space, the top cover 155 is mounted at the opening to abut against the first step 1421 and to press against the end surface of the upper side wall 1522 of the base 1521 so as to cover the pressure balancing film 153, and the pressure balancing film 153 can be effectively protected in extreme working conditions, such as a large amount of gaseous/gaseous media, by providing the top cover 155 with the openings 1551 above the pressure balancing film 153. Further, during the process of installing the top cover 155 into the through opening 141, the edge of the top cover 155 and the inner surface of the wall 142 are in interference fit to fix the top cover 155 in the installation space R3, and at this time, the top cover 155 applies a pressing force to the pressure balance membrane assembly 151 and the second seal 154 toward the second end of the piston 20, so that the second seal 154 is pressed against the third step part 1423 by the lower surface of the base 1521, and the base 1521 of the pressure balance membrane assembly 151 is pressed against the second step part 1422. Whereby the breather 15 is mounted to the end cap 14. The top cover 155, the pressure balance membrane module 151, and the second seal 154 of the present embodiment may be separate components; the breather 15 may also be an integrally formed, unitary component.

The present application also provides a vehicle braking system comprising a low pressure accumulator having a breather 15 with a pressure balancing membrane as above.

According to the above description, in contrast to the prior art, the low pressure accumulator of the present embodiment employs the breather 15 having the pressure balancing membrane to achieve gas communication between the internal space of the low pressure accumulator, particularly the second space R2 accommodating the piston 20, and the external environment so as to maintain pressure equalization therebetween. The vent device 15 is sealingly attached to the port 141 of the end cap 14 by the engagement of the top cap 155, the pressure balance diaphragm assembly 151, the second seal 154, and the stepped

portions

1421, 1422, 1423 formed in the inner surface of the wall 142 in a trapezoidal shape. The venting means 15 has good air permeability and at the same time can effectively prevent liquid/gaseous media in the external environment from entering the inner space of the low pressure accumulator, thereby affecting the normal operation of the low pressure accumulator. The ventilating device 15 in the scheme has simple structure and is easy to install.

Modifications and substitutions to the details may be made by those skilled in the art without departing from the spirit and scope of the invention. The scope of protection of the present invention is limited only by the claims.

Claims

1. A low pressure accumulator for a vehicle braking system, comprising:

2. The low pressure accumulator of claim 1, wherein the brake fluid channel includes a fluid inlet and a fluid outlet through the cylinder, the piston has a first end near the brake fluid channel and a second end toward the end cap, the second end defining a receiving space open toward the end cap, the low pressure accumulator includes a spring having one end abutting against a closed inner end of the receiving space and the other end abutting against the end cap; when brake fluid entering the first space from the fluid inlet acts on the first end of the piston, the piston compresses the spring and moves towards the end cap; when brake fluid flows out of the fluid outlet, the spring is gradually reset, so that the piston moves in a direction away from the end cover.

3. The low pressure accumulator according to claim 2, characterized in that it comprises: the guide rings are respectively fixed on the piston in an embedded mode at two ends of the piston and are used for guiding the piston to reciprocate between two ends of the cylinder body;

a first seal circumferentially disposed between the piston and the inner surface of the cylinder, the guide ring and the first seal both sliding reciprocally against the inner surface of the cylinder as the piston reciprocates between the two ends of the cylinder.

4. A low pressure accumulator according to claim 2 or 3, wherein the end cap has a through opening extending through the end cap, the through opening communicating the second space with the environment, the end cap having a wall projecting around the through opening and extending in the axial direction towards the second space, the wall forming an installation space, the pressure-equalizing membrane being mounted in the installation space, the pressure-equalizing membrane covering the through opening.

5. The low pressure accumulator of claim 4, wherein the venting means comprises a pressure balancing diaphragm assembly comprising a support and a pressure balancing diaphragm supported by the support, the support having a base in the shape of a ring and an upper sidewall projecting from an upper surface of the base and continuously distributed in the circumferential direction of the base, the pressure balancing diaphragm being carried by the base and secured in a space surrounded by the upper sidewall, the support further having a lower sidewall projecting from a lower surface of the base and continuously distributed in the circumferential direction of the base, the lower sidewall being radially inward of the upper sidewall; the inner surface of the wall is provided with second steps distributed along the circumferential direction, and the lower surface of the base abuts against the second steps when the pressure balance membrane assembly is installed in the installation space.

6. The low pressure accumulator of claim 5, wherein the breather device includes a second seal circumferentially surrounding the lower sidewall, the wall having a circumferentially distributed third step on an inner surface thereof, the third step being located on a side of the second step toward the second end of the piston, the third step narrowing in a radial direction relative to the second step within the mounting space, the second seal being disposed between the lower sidewall and the inner surface of the wall when the pressure balancing diaphragm assembly is mounted in the mounting space, and the second seal being pressed against the third step by the lower surface.

7. The low pressure accumulator of claim 6, wherein the length of the second seal in the axial direction is greater than the distance between the second step and the third step.

8. The low pressure accumulator according to claim 6, characterized in that the venting means comprise a top cover with several openings through the top cover, the wall having on its inner surface circumferentially distributed first steps on the side of the second step facing away from the second end of the piston, the second step narrowing in the mounting space in a radial direction with respect to the first step, the top cover being mounted at the opening against the first steps and against the end face of the upper side wall covering the pressure balancing membrane.

9. The low pressure accumulator of claim 8 wherein when the cap is mounted at the through opening, the edge of the cap is in interference fit with the inner surface of the wall so that the cap is secured within the mounting space.

10. A vehicle braking system comprising a low pressure accumulator as claimed in any one of claims 1 to 9.