Vehicle brake system and accumulator therefor

Abstract

A vehicle brake system comprising an accumulator (40) including a cylinder (410) having a first end defining a fluid port (412), and an end cap (450) mounted to a second end of the cylinder (410) and cooperatively defining with the cylinder (410) a piston cavity (430) in fluid communication with the fluid port (412), and a piston (440) housed within the piston cavity (430) and axially reciprocally movable therein, a resilient element (460) interposed between the piston (440) and the end cap (450), the piston cavity (430) being divided by the piston (440) into a high pressure side in fluid communication with the fluid port (412) and a low pressure side in which the resilient element (460) resides, wherein the accumulator (40) further comprises a bleed port (499) configured to direct brake fluid leaked from the high pressure side of the piston cavity (430) to the low pressure side of the piston cavity (430) away from the low pressure side. The application also relates to an accumulator in such a vehicle brake system.

Description

Technical Field

[0001] The present invention relates to a vehicle brake system and an energy accumulator for the vehicle brake system. Background Art

[0002] Vehicles are typically equipped with a vehicle braking system to provide safe braking. This system primarily consists of a brake circuit and a master cylinder that supplies brake fluid to the circuit. The brake circuit incorporates hydraulic components such as solenoid control valves, accumulators, and pumps to achieve and control the brake pressure transmitted to the wheel cylinders at the wheels. The accumulator is an energy storage device within the brake circuit, filling with brake fluid to store energy in the system and discharging it to release energy as needed.

[0003] An accumulator consists of a cylinder and a piston that reciprocates axially within it. Two guide rings are typically positioned between the piston and the cylinder, providing guidance, and a seal between the two guide rings. As the piston moves axially within the cylinder, the guide rings and seal slide back and forth against the inner surface of the cylinder.

[0004] On the one hand, the reciprocating motion of the hard guide ring may cause scratches or other friction defects on the inner surface of the cylinder body where it slides. When the elastic seal moves into contact with this scratched area, it can no longer effectively seal the outer surface of the piston and the inner surface of the cylinder body, which may cause brake fluid leakage. On the other hand, aging and wear of the seal can also cause brake fluid leakage. If the leaked brake fluid accumulates to a certain level, it will not only affect the movement of the piston and thus the performance of the accumulator, but also put the accumulator end cap at risk of bursting.

[0005] Hopefully the above technical problems can be solved. Summary of the Invention

[0006] The purpose of the present application is to reduce or even eliminate the influence of brake fluid leaking from the accumulator on the accumulator and thus on the wheel braking system.

[0007] The above-mentioned object of the present application is achieved by a vehicle braking system including an accumulator, wherein the accumulator includes:

[0008] a cylinder having a first end defining a fluid port; and

[0009] an end cap mounted on the second end of the cylinder and defining, together with the cylinder, a piston chamber in fluid communication with the fluid port; and

[0010] A piston is accommodated in the piston cavity and is capable of axially reciprocating therein. The elastic element is sandwiched between the piston and the end cover. The piston cavity is divided by the piston into a high-pressure side in fluid communication with the fluid port and a low-pressure side where the elastic element is located.

[0011] The present application also relates to an accumulator, which is the accumulator used in the above vehicle braking system.

[0012] The vehicle braking system of the present application addresses the adverse effects of inevitable brake fluid leakage within the accumulator on the accumulator by providing a drain port that directs leaked brake fluid away from the piston chamber. The provision of the drain port achieves the technical purpose of promptly and completely draining brake fluid leaking between the accumulator's cylinder and piston out of the piston chamber, minimizing or even eliminating the effects of brake fluid leakage on the accumulator and, consequently, the braking system. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing and other aspects of the present application will be more fully understood from the detailed description given below in conjunction with the accompanying drawings. It should be noted that, for the purposes of clarity and emphasis, the drawings are not drawn to scale, and portions not relevant to the focus of the present application may be omitted, but this does not affect the understanding of the present application. For example, the vehicle brake system of the present application may also include many components that are not shown in the drawings because they are not relevant to the focus of the present application, and the components shown in the drawings are not necessarily present in all embodiments of the vehicle brake system.

[0014] In the attached figure:

[0015] Figure 1 A simplified hydraulic circuit diagram illustrating a portion of a vehicle brake system according to a first embodiment of the present application;

[0016] Figure 2 A simplified hydraulic circuit diagram illustrating a portion of a vehicle brake system according to a second embodiment of the present application;

[0017] Figure 3 Is suitable for Figure 1 A cross-sectional view of a portion of an accumulator used in a vehicle braking system. DETAILED DESCRIPTION

[0018] In the various drawings of the present application, components or features with the same structure or similar functions are denoted by the same reference numerals.

[0019] like Figure 1As shown, the vehicle brake system according to the first embodiment of the present application comprises a master cylinder 10, a brake fluid reservoir 20 storing brake fluid, and a brake pedal 30 operatively connected to the master cylinder 10. The master cylinder 10 is in selective fluid communication with the brake fluid reservoir 20 to receive brake fluid therefrom, and a brake booster (not shown) can be connected between the master cylinder 10 and the brake pedal 30. Actuation or depression of the brake pedal 30 can cause the master cylinder 10 to be pressurized and bled by the brake booster to provide brake fluid. This part is not the focus of the present application and will not be explained in detail here.

[0020] Figure 1 The vehicle brake system shown is a diagonal dual-circuit brake system, and the part of the brake system shown in the figure is for the brake circuit portion of the left rear wheel and the right front wheel.

[0021] In the brake circuit shown, the vehicle brake system comprises a brake line including a main brake line L1 starting from the fluid outlet of the master cylinder 10 and a first sub-brake line L11 and a second sub-brake line L12 formed by the main brake line L1 after passing through the always-open control valve 15, the first sub-brake line L11 and the second sub-brake line L12 being respectively provided with a first always-open control valve 25 and a second always-open control valve 35, the first always-open control valve 25 being configured to control the brake wheel cylinder 26 of the left rear wheel, and the second always-open control valve 35 being configured to control the brake wheel cylinder 36 of the right front wheel. In the present application, the always-open control valves 25 and 35 can be configured as two-position solenoid valves that can be switched between a conductive state allowing fluid flow and a cut-off state prohibiting fluid flow under the control of an electronic control device, such as the central electronic control unit (ECU) of the vehicle. The "always-open control valve" means that the valve is always in the conductive state when not powered, and is switched to the cut-off state when powered.

[0022] In Figure 1In the illustrated brake circuit, the vehicle braking system also includes a release circuit, comprising a first sub-release circuit L21 originating from the left rear wheel brake cylinder 26 and a second sub-release circuit L22 originating from the right front wheel brake cylinder 36. The first sub-release circuit L21 and the first sub-release circuit L22 are each equipped with a normally closed control valve 45 and 55. After passing through their respective normally closed control valves 45 and 55, the first sub-release circuit L21 and the first sub-release circuit L22 converge into a main release circuit L2. The main release circuit L2 is equipped with an accumulator 40 and a pump 50 located downstream of the accumulator 40 along the flow direction of the brake fluid. The fluid outlet of the pump 50 leads to the main brake circuit L1, thereby fluidically connecting the main release circuit L2 to the main brake circuit L1. Similar to a normally open control valve, a "normally closed control valve" refers to a valve that is always in the closed state when not powered and switches to the open state when powered. The state and switching of each control valve in this application and / or the state of the brake pedal 30 can be monitored or controlled by the vehicle's ECU.

[0023] Alternatively, as Figure 1 As shown, in order to provide overpressure protection, a one-way valve 14, 24 and 34 can be connected in parallel to each normally open control valve 15, 25 and 35.

[0024] like Figure 1 In the vehicle braking system shown, when the brake pedal 30 is actuated, for example, when the driver steps on the brake pedal 30 while driving the vehicle, the booster generates power assistance due to the pressure difference, and the master brake cylinder 10 generates braking pressure by receiving the amplified force from the booster, so that the brake fluid therein is pressurized and discharged from the fluid outlet to the main brake line L1. The brake fluid entering the main brake line L1 passes through the normally-open control valve 15 in the on state and the normally-open control valve 25 in the on state in sequence and enters the brake wheel cylinder 26 of the left rear wheel, providing braking force to the left rear wheel. Similarly, the brake fluid entering the main brake line L1 passes through the normally-open control valve 15 in the on state and the normally-open control valve 35 in the on state in sequence and enters the brake wheel cylinder 36 of the right front wheel, providing braking force to the right front wheel.

[0025] When the brake pedal 30 is released, or for other reasons, the brake pressure within the wheel cylinders needs to be reduced. Under the control of an electronic control device, such as the vehicle ECU, normally closed control valves 45 and 55 are switched from a closed state to a closed state. This switches the normally open control valves 45 and 55 in the branch brake lines L11 and L12 from an open state to a closed state. This allows the brake fluid in wheel cylinders 26 and 36 to enter branch release lines L21 and L22 and pass through the normally closed control valves 45 and 55, which have been switched to an open state. After flowing through the normally closed control valves 45 and 55, the brake fluid in the branch release lines L21 and L22 converges into the main release line L2, where it enters and is stored in accumulator 40. When motor 70 is activated, pump 50 is activated, discharging the pressurized brake fluid in accumulator 40, opening check valve 60, and pumping the fluid into pump 50. Pump 50 then pumps the brake fluid to the main brake line L1, where it returns to master cylinder 10 via normally open control valve 15.

[0026] The above describes the working principle of one of the brake circuits of the vehicle braking system of this first embodiment. Those skilled in the art should understand that the other brake circuit composed of the brake wheel cylinder for the left front wheel and the brake wheel cylinder for the right rear wheel is similar to the above-mentioned brake circuit composed of the brake wheel cylinder for the left rear wheel and the brake wheel cylinder for the right front wheel, and will not be repeated here.

[0027] from Figure 1 In the embodiment shown, the vehicle brake system further includes a drain line L3 that establishes fluid communication between the accumulator 40 and the brake fluid reservoir 20. Drain line L3 is configured to direct leaked brake fluid from the accumulator 40 to the brake fluid reservoir 20, which is maintained at normal pressure. If brake fluid leakage from the accumulator 40 is unavoidable, providing a drain line L3 to promptly drain the leaked fluid is highly advantageous. This allows the leaked fluid to be promptly discharged from the accumulator without compromising the accumulator's functionality and performance.

[0028] Figure 2 This is a hydraulic circuit diagram of a portion of a vehicle braking system according to a second embodiment of the present application. Figure 1 The first embodiment of the present invention is that the drain line L3 is configured to direct brake fluid leaking from the accumulator 40 into the brake fluid flow discharged from the accumulator 40 to the pump 50. Under the negative pressure generated by the activation of the pump 50, the pressurized brake fluid in the accumulator 40 is discharged, and the brake fluid leaking from the accumulator 40 is introduced into this negative pressure environment. This negative pressure environment allows the leaked brake fluid in the accumulator 40 to be discharged more completely.

[0029] Alternatively, as Figure 2As shown, a one-way valve 42 is provided at the discharge port of the accumulator 40. The opening pressure of the one-way valve is set to 0, that is, it does not hinder the discharge of the brake fluid leaked from the accumulator 40. However, the provision of the one-way valve advantageously eliminates the possibility of brake fluid flowing back into the accumulator in an unexpected situation.

[0030] Figure 3 Shows that it is suitable for Figure 1 and 2 1 is a cross-sectional view of a portion of an accumulator 40 used in a vehicle braking system.

[0031] The accumulator 40 includes a cylinder body 410 including a side portion 414, which may be integrally formed as shown or formed separately and then sealingly attached together, and a first end portion 416, which defines a fluid port 412 for allowing brake fluid to enter and exit the accumulator 40. A cylinder head or plug 450 is sealingly mounted to a second end of the cylinder body 410. The cylinder body 410 and the cylinder head 450 together define a piston chamber 430, in which a piston 440 is received and reciprocally movable in an axial direction Z.

[0032] With respect to piston chamber 430, the side of piston 440 near fluid port 412 of cylinder body 410 is referred to as the high-pressure side thereof, whereas the side where elastic element 460 is located is referred to as the low-pressure side. Elastic element 460 is sandwiched between piston 440 and end cap 450 on the low-pressure side of piston chamber 430. Elastic element 460 may be a spring or any other type of elastic element.

[0033] exist Figure 3 In the embodiment, one end of the elastic element 460 abuts the piston 440, and the other end abuts the end cap 450. The end cap 450 is a solid part including a solid base 452 and a boss 454 protruding from the solid base 452 toward the piston chamber 430. The elastic element 460 is partially fitted onto the boss 454 of the end cap 450 to stabilize and fix the position of the elastic element 460. In a structure not shown, the piston 440 may be formed with a recess extending from the low-pressure side end surface of the piston 440 toward the interior of the piston 440 and terminating therein, for receiving at least a portion of the elastic element 460 to similarly stabilize and fix the elastic element 460.

[0034] When brake fluid from the brake cylinder enters the piston chamber 430 through the fluid port 412 of the accumulator 40, the brake fluid reaches the high-pressure side of the piston chamber 430. This brake fluid causes the piston 440 to move toward the low-pressure side against the elastic force of the elastic element 460, thereby completing the energy storage operation. When the pump 50 of the vehicle brake system is activated, the brake fluid on the high-pressure side of the piston chamber 430 is pumped out of the accumulator 40 through the fluid port 412, causing the elastic element 460 to move toward the high-pressure side of the piston, releasing energy.

[0035] The accumulator 40 further includes a first guide ring 480 and a second guide ring 490 disposed on the piston 440 near the high-pressure side and the low-pressure side of the piston chamber 430, respectively, to guide the piston 440 as it moves axially within the piston chamber 430. A seal 470 is disposed between the first guide ring 480 and the second guide ring 490 along the axial direction Z.

[0036] exist Figure 3 In the structure, the piston 440 is formed on its outer surface with annular grooves 485, 495 and 475 suitable for installing the first guide ring 480, the second guide ring 490 and the seal 470. In the illustrated embodiment, the first guide ring 480 and the second guide ring 490 are formed as rings with openings so that they can be clamped into the corresponding annular grooves 485 and 495 of the piston 440 before the piston 440 is installed in the piston chamber 430. The seal 470 can be a sealing element well known to those skilled in the art, such as an O-ring. Similarly, before the piston 440 is installed in the piston chamber 430, the seal 470 is fitted and clamped in the annular groove 475. Although Figure 3 The above structure is shown in FIG. 1 , but those skilled in the art will appreciate that the first guide ring 480, the second guide ring 490 and the seal 470 may have different Figure 3 The configuration shown, for example, one of the first guide ring 480 and the second guide ring 490 can be designed to fit on the inner surface formed on the cylinder body 410 facing the piston chamber 430 and is designed not to interfere with the reciprocating axial movement of the seal 470 during the axial movement of the piston 440, which can reduce the wear of the seal 470 to a certain extent, thereby reducing the leakage of brake fluid.

[0037] However, it is inevitable that the brake fluid leaks from the high-pressure side of the piston 440 to the low-pressure side of the piston 440 through the space between the outer surface of the piston 440 and the inner surface of the piston chamber 430 that move relatively.

[0038] In order to solve the problem of leaked brake fluid damaging the performance of the accumulator 40, a method of promptly draining the leaked brake fluid can be adopted. To this end, the accumulator 40 of the present application includes a drain port 499 configured to discharge the brake fluid leaked from the high-pressure side of the piston 440 to the low-pressure side.

[0039] according to Figure 1 In the first embodiment of the vehicle brake system, the leaked brake fluid is discharged to a container under normal pressure, such as a brake fluid reservoir or any other container. At this time, the drain port 499 extends through the cylinder 410 to the outside of the accumulator 40, such as Figure 3When in use, an external pipeline is connected at the discharge port 499, and the other end of the external pipeline leads to a container in a normal pressure environment. The external pipeline can be any suitable pipeline commonly used in the art, such as a rigid metal hard pipe, preferably a non-metallic flexible pipe that can provide portability and flexibility.

[0040] Optionally, according to Figure 2 In the second embodiment of the vehicle brake system, the leaked brake fluid is discharged into a negative pressure environment. To this end, the drain port 499 can be configured to be connected to the main release line L2 through an internal pipe formed inside the cylinder 410 of the accumulator 40 and / or an external pipe located outside the cylinder 410 of the accumulator 40 as described above, so that when the accumulator 40 discharges the high-pressure brake fluid, the brake fluid leaked to the low-pressure side of the piston 440 is also sucked into the pump 50. In this embodiment, as Figure 2 The one-way valve 42 shown is necessary to allow brake fluid to drain out of the low-pressure side while preventing brake fluid from entering the piston chamber 430 from the low-pressure side. In this case, although not shown, the drain port 400 may be connected to the fluid port 412 via a fluid passage inside the cylinder 410 without penetrating the cylinder 410.

[0041] This application does not limit the number, shape, size and arrangement of the drain openings 499 .

[0042] Alternatively, since the end cover 450 defines the piston chamber 430, specifically, at least a portion of the low-pressure side of the piston 440, it is also possible to dispose the drain port 499 at an appropriate position on the end cover 450. Furthermore, the drain port 499 of the accumulator 40 may extend through both the cylinder body 410 and the end cover 450, as long as the brake fluid leaking to the low-pressure side of the piston 440 can be guided to the outside of the cylinder body 410.

[0043] According to the present application, since the drain port 499 is provided, the end cover 450 of the accumulator 40 no longer needs to be processed with a through hole for setting a permeable component, which reduces the processing and manufacturing cost of the end cover 450 and eliminates the need to set a relatively expensive permeable component in the end cover 450.

[0044] The vehicle brake system of the present application has been described in detail above with reference to the specific embodiments of the accompanying drawings. When accumulator leakage cannot be completely avoided, the accumulator of the present application achieves the purpose of promptly directing leaked brake fluid out of the accumulator, thereby avoiding, or even eliminating, the technical problem of leaked brake fluid damaging accumulator performance. Leaked brake fluid can be directed into a normal pressure environment or into a negative pressure environment, which allows for more complete discharge of the leaked brake fluid.

[0045] Those skilled in the art should also understand that the present application is not limited to the specific embodiments shown in the drawings and described above, and various replacements, changes and modifications can be conceived without departing from the spirit and scope of the present application.

Claims

1. A vehicle braking system comprising an accumulator (40), the accumulator (40) comprising: a cylinder (410) having a first end defining a fluid port (412) for allowing brake fluid to enter and exit the accumulator (40); and an end cap (450) mounted on the second end of the cylinder (410) and defining, together with the cylinder (410), a piston chamber (430) in fluid communication with the fluid port (412); and A piston (440) is accommodated in the piston chamber (430) and is capable of axially reciprocating therein. An elastic element (460) is sandwiched between the piston (440) and the end cover (450). The piston chamber (430) is divided by the piston (440) into a high-pressure side in fluid communication with the fluid port (412) and a low-pressure side where the elastic element (460) is located. The accumulator (40) further includes a drain port (499) configured to guide brake fluid leaking from the high-pressure side of the piston chamber (430) to the low-pressure side of the piston chamber (430) away from the low-pressure side.

2. The vehicle braking system according to claim 1, wherein: The drain port (499) is configured to guide the leaked brake fluid to a container in a normal pressure environment via an external pipe located outside the cylinder (410).

3. The vehicle braking system according to claim 2, wherein: The external pipe is a rigid pipe or a flexible pipe.

4. The vehicle braking system according to claim 1, wherein: The drain port (499) is configured to allow the brake fluid leaking to the low-pressure side to flow into the brake fluid flow discharged from the fluid port (412) via an external pipe located outside the cylinder body (410) and / or via an internal pipe extending inside the cylinder body (410).

5. The vehicle braking system according to claim 4, wherein: The drain port (499) is provided with a one-way valve that only allows the leaked brake fluid to flow out of the low-pressure side but does not allow the brake fluid to enter the low-pressure side.

6. The vehicle braking system according to claim 5, wherein: The opening pressure of the one-way valve is approximately zero.

7. The vehicle braking system according to any one of claims 1 to 6, wherein: The drain port (499) is formed in at least one of the cylinder (410) and the end cover (450).

8. The vehicle braking system according to any one of claims 1 to 6, wherein: The end cover (450) of the accumulator (40) is a solid part.

9. The vehicle braking system according to any one of claims 1 to 6, further comprising a first guide ring (480) and a second guide ring (490) disposed between the piston (440) and the cylinder (410) near the high-pressure side and the low-pressure side.

10. The vehicle braking system according to claim 9, wherein: The first guide ring (480) and the second guide ring (490) are ring-shaped members with openings.

11. The vehicle braking system according to claim 10, wherein: One of the first guide ring (480) and the second guide ring (490) is clamped in an annular groove formed on the outer surface of the piston (440) facing the cylinder body (410), and the other of the first guide ring and the second guide ring is clamped in an annular groove formed on the outer surface of the piston (440) facing the cylinder body (410) or in an annular groove formed on the inner surface of the cylinder body (410) facing the piston (440).

12. The vehicle braking system according to claim 9, further comprising a seal (470) axially disposed between the first guide ring and the second guide ring, wherein an outer surface of the piston (440) is formed with a sealing groove (475) for receiving the seal (470).

13. An accumulator, the accumulator being the accumulator (40) used in the vehicle braking system according to any one of claims 1 to 12.

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