DE112021000147T5 - Vehicle braking system and accumulator thereof - Google Patents

Abstract

In the present application there is disclosed a vehicle braking system comprising an accumulator (40), the accumulator (40) comprising: a cylinder (410) having a first end portion defining a fluid passage (412); and an end cap (450) installed at a second end portion of the cylinder (410) and together with the cylinder (410) defines a piston chamber (430) in flow communication with the fluid passage (412); and a piston (440) received in the piston chamber (430) and axially reciprocable therein, with a resilient member (460) being clamped between the piston (440) and the end cap (450) and the piston chamber (430) is divided by the piston (440) into a high-pressure side, which is in flow communication with the fluid channel (412), and a low-pressure side, on which the elastic element (460) is positioned, the pressure accumulator (40) further having a A bleed passage (499) configured to direct brake fluid that has leaked 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.

Description

technical field

The present invention relates to a vehicle braking system and an accumulator for the vehicle braking system.

State of the art

A vehicle braking system is generally installed in a vehicle to provide safe braking of the vehicle. The vehicle brake system mainly includes a brake circuit and a brake master cylinder that supplies brake fluid to the brake circuit. The brake circuit contains hydraulic elements such. B. an electromagnetic control valve, an accumulator and a pump to generate and control brake pressure, which is transmitted to a wheel brake cylinder at a wheel. The accumulator is an energy storage device in the brake circuit that is filled with brake fluid to store energy in the system or drains brake fluid to release energy as needed.

The accumulator includes a cylinder and a piston that reciprocates axially within the cylinder. Two guide rings serving a guiding function and a sealing member serving a sealing function between the two guide rings are generally provided between the piston and the cylinder. As the piston moves axially within the cylinder, the guide rings and sealing member all slide in a stroke-like manner upon abutment with an inner surface of the cylinder.

During the stroke movement, the guide rings made of a hard material may cause scratches or other frictional defects on the inner surface of the cylinder in sliding contact with it, in which case the sealing member made of an elastic material becomes unable to move into contact with this scratched area is to effectively seal the outer surface of the piston from the inner surface of the cylinder, potentially resulting in brake fluid leakage; in addition, aging and wear of the sealing member can also cause brake fluid leakage. If leaked brake fluid accumulates to a certain extent, it will affect piston movement and thus accumulator performance, and there is a risk of an accumulator end cap bursting.

It is hoped that these technical problems can be resolved.

Summary of the Invention

One object of the present application is to reduce or even eliminate the effects that escaping brake fluid in the pressure accumulator has on the pressure accumulator and thus on the wheel brake system.

• einen Zylinder, der einen ersten Endteil aufweist, der einen Fluidkanal definiert; und
• eine Endkappe, die an einem zweiten Endteil des Zylinders installiert ist und zusammen mit dem Zylinder eine Kolbenkammer in Strömungsverbindung mit dem Fluidkanal definiert; und
• einen Kolben, der in der Kolbenkammer aufgenommen ist und sich axial darin hin- und herbewegen kann, wobei ein elastisches Element zwischen dem Kolben und der Endkappe eingespannt ist und die Kolbenkammer von dem Kolben in eine Hochdruckseite, die mit dem Fluidkanal in Strömungsverbindung steht, und eine Niederdruckseite, an der das elastische Element positioniert ist, unterteilt wird.

The above object of the present application is achieved by a vehicle braking system comprising an accumulator, the accumulator comprising:

• a cylinder having a first end portion defining a fluid passage; and
• an end cap installed at a second end portion of the cylinder and defining, together with the cylinder, a piston chamber in flow communication with the fluid passage; and
• a piston received in the piston chamber and capable of axial reciprocation therein with a resilient member constrained between the piston and the end cap and the piston chamber extending from the piston into a high pressure side in fluid communication with the fluid passage, and a low pressure side where the elastic member is positioned is divided.

The present application also relates to an accumulator, which is the accumulator used in the vehicle braking system as described above.

In the vehicle brake system according to the present application, by providing a bleed passage for conducting leaked brake fluid away from the piston chamber, the adverse effect on the accumulator of brake fluid leakage in the accumulator, which is difficult to avoid, is eliminated. The provision of the bleed passage solves the technical task of immediately and thoroughly discharging from the piston chamber any brake fluid that has leaked between the cylinder and the piston of the accumulator, thereby reducing the effect that the leakage of brake fluid has on the accumulator and thus on the braking system has, is reduced to the maximum or even eliminated.

character list

• 1 schematisch ein hydraulisches Schaltbild eines Teils eines Fahrzeugbremssystems gemäß einer ersten Ausführungsform der vorliegenden Anmeldung.
• 2 schematisch ein hydraulisches Schaltbild eines Teils eines Fahrzeugbremssystems gemäß einer zweiten Ausführungsform der vorliegenden Anmeldung.
• 3 eine Schnittansicht eines Teils eines Druckspeichers, der sich zur Verwendung bei dem Fahrzeugbremssystem von 1 eignet.

A more complete understanding of the above and other aspects of the present application can be obtained from the following detailed explanation in conjunction with the drawings. It is noted that in order to provide a clear explanation and highlight the essential points, the drawings are not scaled are drawn to the bar and parts not related to the essential points of the present application may be omitted, but this does not impair the understanding of the present application. For example, the vehicle braking system of the present application may also include many components that are not shown in the drawings because they are not related to the gist of the present application, and the components shown in the drawings need not be common to all embodiments of the invention Vehicle braking system must be present. In the drawings show:

• 1 schematically shows a hydraulic circuit diagram of a part of a vehicle brake system according to a first embodiment of the present application.
• 2 schematically shows a hydraulic circuit diagram of part of a vehicle brake system according to a second embodiment of the present application.
• 3 FIG. 12 is a sectional view of a portion of an accumulator suitable for use in the vehicle braking system of FIG 1 suitable.

Detailed description of the invention

In the drawings of the present application, structurally identical or functionally similar components or features are identified using the same reference numbers.

As in 1 1, a vehicle braking system according to a first embodiment of the present application includes a brake master cylinder 10, a brake fluid reservoir 20 storing brake fluid, and a brake pedal 30 operatively connected to the brake master cylinder 10. FIG. The master cylinder 10 is selectively in fluid communication with the brake fluid reservoir 20 to receive brake fluid therefrom, and a brake booster (not shown) may be connected between the master cylinder 10 and the brake pedal 30 . Depressing or depressing the brake pedal 30 may cause the master cylinder 10 to receive brake boost from the brake booster to pressurize the brake fluid within the master cylinder 10 and route it to the outside. This part is not the focus of the present application and is therefore not explained in more detail here.

This in 1 Vehicle braking system shown is a diagonal dual circuit braking system; the figure shows the brake circuit part used for the left rear wheel and the right front wheel.

In the brake circuit shown in the figure, the vehicle brake system includes a brake pipe. The brake pipe includes a main brake pipe L1 starting at a fluid outlet of the master cylinder 10, and a first secondary brake pipe L11 and a second secondary brake pipe L12 formed by branching from the main brake pipe L1 after passing through a normally open control valve 15. A first normally-open control valve 25 and a second normally-open control valve 35 are provided on the first secondary brake line L11 and the second secondary brake line L12, respectively. The first normally open control valve 25 is configured to control a wheel brake cylinder 26 on the left rear wheel, and the second normally open control valve 35 is configured to control a wheel brake cylinder 36 on the right front wheel. In the present application, the normally-open control valves 25 and 35 may be configured as a two-position solenoid valve that operates between an open state that allows fluid flow therethrough and a closed state that prevents fluid flow therethrough under the control of an electronic control device such as an electronic controller . B. a central electronic control unit of the vehicle (ECU) can change. The term "normally open control valve" means that when de-energized the valve is continuously in the open state and when energized transitions to the blocking state.

in the in 1 Brake circuit shown, the vehicle brake system also includes a release line. The release line comprises a first secondary release circuit L21, which starts at the wheel brake cylinder 26 of the left rear wheel, and a second secondary release circuit L22, which starts at the wheel brake cylinder 36 of the right front wheel. The first secondary release circuit L21 and the first secondary release circuit L22 are provided with normally-closed control valves 45 and 55, respectively. After passing through their respective normally closed control valves 45 and 55, the first secondary release circuit L21 and the first secondary release circuit L22 converge to form a main release circuit L2. An accumulator 40 and a pump 50 positioned downstream of the accumulator 40 in the direction of brake fluid flow are provided on the main release circuit L2. A fluid outlet of the pump 50 leads to the main brake line L1 so that the main release circuit L2 is fluidly connected to the main brake line L1 at this point. Similar to a normally open control valve, the term "normally closed control valve" means that when the valve is not energized, is constantly in the locked state and, when energized, changes to the open state. The states and cycling of the various control valves in the present application and/or the states of the brake pedal 30 may all be monitored or controlled by the vehicle ECU.

Optionally, as in 1 As shown, a one-way valve 14, 24, 34 may be connected in parallel with each normally open control valve 15, 25, 35 to provide over-pressure protection.

At the in 1 generated vehicle braking system shown when the brake pedal 30 is operated, z. B. a driver depresses the brake pedal 30 while driving the vehicle, the booster a boost due to a pressure difference, and the master cylinder 10 generates brake pressure by receiving a boosted force from the booster so that the brake fluid is pressurized therein and through the fluid outlet to the brake master pipe L1 is omitted. The brake fluid entering the brake master line L1 sequentially flows through the normally-open control valve 15 in the open state and the normally-open control valve 25 in the open state, and enters the rear-left wheel brake cylinder 26 to supply braking force to the rear-left wheel. Likewise, the brake fluid entering the brake master line L1 sequentially flows through the normally-open control valve 15 in the open state and the normally-open control valve 35 in the open state, and enters the wheel-brake cylinder 36 of the front-right wheel to supply braking force to the front-right wheel .

When the brake pedal 30 is released, or when the brake pressure in the wheel brake cylinders has to be reduced for any other reason, under the control of an electronic control device, such as e.g. B. the vehicle ECU, the normally-closed control valves 45 and 55 from the closed state to the open state, and the normally-open control valves 45 and 55 on the secondary brake lines L11 and L12 change from the open state to the closed state, so that the brake fluid in the wheel brake cylinders 26 and 36 enters the secondary release lines L21 and L22 and flows through the normally closed control valves 45 and 55 which have already changed to the open state. After passing through the normally closed control valves 45 and 55, the brake fluid in the secondary release lines L21 and L22 joins in the main brake line L2, enters the accumulator 40 and is stored therein. When a motor 70 is activated, the pump 50 is activated and the brake fluid pressurized in the accumulator 40 can be released by opening a one-way valve 60 and is extracted into the pump 50. The brake fluid is then pumped by the pump 50 to the brake master line L1 and returns to the brake master cylinder 10 via the normally open control valve 15 .

The operating principles of one of the brake circuits of the vehicle brake system of this first embodiment have been described above, but it is obvious to those skilled in the art that another brake circuit formed by a wheel brake cylinder for the left front wheel and a wheel brake cylinder for the right rear wheel is the one described above Brake circuit, which is formed by the wheel brake cylinder for the left rear wheel and the wheel brake cylinder for the right front wheel, is similar, so that the description is not repeated here.

From the embodiment of 1 It can be seen that the vehicle brake system further includes a discharge line L3 which establishes a flow connection between the pressure accumulator 40 and the brake fluid reservoir 20 . The drain line L3 is configured to lead leaked brake fluid in the accumulator 40 to the brake fluid reservoir 20, which is in an atmospheric pressure environment. In a situation where leakage of brake fluid in the accumulator 40 is unavoidable, the presence of the drain line L3 for promptly draining leaked brake fluid is of great advantage; this enables the leaked brake fluid to be promptly discharged from the accumulator so that it no longer affects the functional performance and characteristics of the accumulator.

2 13 is a hydraulic circuit diagram of part of the vehicle brake system according to a second embodiment of the present application. This embodiment differs from the first embodiment of FIG 1 in that the drain line L3 in this embodiment is constructed to lead leaked brake fluid in the accumulator 40 into the flow of brake fluid drained from the accumulator to the pump 50. With negative pressure generated upon actuation of the pump 50, pressurized brake fluid in the accumulator 40 is discharged, and the leaked brake fluid in the accumulator 40 is introduced into this negative pressure environment. Due to this negative pressure environment, the leaked brake fluid in the accumulator 40 is discharged more thoroughly.

Optionally, as in 2 As shown, a one-way valve 42 is provided at a discharge passage of the accumulator 40; the opening pressure of this one-way valve is set to 0, that is, the one-way valve does not constitute an obstacle to the discharge of the leaked brake fluid in the accumulator 40. However, the provision of this one-way valve advantageously eliminates the possibility of brake fluid accidentally flowing back into the accumulator.

3 12 shows a sectional view of a portion of the accumulator 40 suitable for use in the vehicle braking systems of FIG 1 and 2 suitable.

The accumulator 40 includes a cylinder 410, the cylinder 410 including a side portion 414 and a first end portion 416, which may be integrally formed as shown in the figure, or formed separately and then sealingly attached to one another; the first end portion 416 defines a fluid passage 412 that allows brake fluid to enter and exit the accumulator 40 . A cylinder cap or plug 450 is sealingly installed at a second end portion of the cylinder 410 . Cylinder 410 and cylinder cap 450 together define a piston chamber 430; a piston 440 is received in the piston chamber 430 and can reciprocate therein in an axial Z direction.

As for the piston chamber 430, a side where the piston 440 is close to the fluid passage 412 of the cylinder 410 is referred to as a high-pressure side thereof, and in contrast, a side where an elastic member 460 is positioned is referred to as denotes a low-pressure side. On the low-pressure side of the piston chamber 430, the elastic element 460 is clamped between the piston 440 and the end cap 450. The elastic element 460 can be a spring or any other form of elastic element.

In 3 one end of the elastic member 460 abuts the piston 440 and another end abuts the end cap 450; the end cap 450 is a solid component that includes a solid base 452 and a lug 454 protruding from the solid base 452 to the piston chamber 430, and the resilient member 460 is partially fitted around the lug 454 of the end cap 450 to to stabilize and fix the position of the elastic member 460. In a structure not shown, the piston 440 may be formed to have a recess extending from a low-pressure side end surface of the piston 440 into the piston 440 and terminating inside thereof for the purpose of receiving at least part of the elastic Has element 460 in order to achieve the goal of stabilizing and fixing the elastic element 460 alike.

When brake fluid from the brake cylinder enters the piston chamber 430 via the fluid passage 412 of the accumulator 40, the brake fluid reaches the high-pressure side of the piston chamber 430; the brake fluid causes the piston 440 to move to the low-pressure side against the elastic force of the elastic member 460, and the elastic member 460 realizes the energy storage operation. When the pump 50 of the vehicle braking system is activated, the brake fluid, which is on the high-pressure side of the piston chamber 430, is sucked out of the accumulator 40 via the fluid passage 412, and the elastic element 460 moves to the high-pressure side of the piston, thereby releasing energy .

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; these serve a guiding function when the piston 440 moves axially in the piston chamber 430 . A seal member 470 is interposed between the first guide ring 480 and the second guide ring 490 in the axial Z direction.

In the structure of 3 Ring grooves 485, 495 and 475 suitable for installing the first guide ring 480, the second guide ring 490 and the seal member 470 are formed on an outer surface of the piston 440. In the embodiment shown, the first guide ring 480 and the second guide ring 490 are formed as annular members with openings and thus can be engaged with the corresponding annular grooves 485 and 495 of the piston 440 before the piston 440 is installed in the piston chamber 430. The sealing member 470 can be a sealing element known to those skilled in the art, e.g. B. an O-ring. Likewise, before the piston 440 is installed in the piston chamber 430, the sealing member 470 is engaged with the annular groove 475 in a sealing manner. Although the structure described above in 3 is shown, it will be apparent to those skilled in the art that the first guide ring 480, the second guide ring 490 and the sealing member 470 have a different configuration than those shown in FIG 3 is shown, may have. For example, the first guide ring 480 or the second guide ring 490 can be constructed so that it is adapted to be formed on an inner surface of the cylinder 410 that faces the piston chamber 430 and constructed so that it is not interferes with the axial reciprocating movement of the seal member 470 in the course of axial movement of the piston 440. This can reduce wear of the seal member 470 to some extent and thus can reduce brake fluid leakage.

However, leakage of brake fluid from the high-pressure side of the piston 440 to the low-pressure side of the piston 440 through a clearance between an inner surface of the piston chamber 430 and an outer surface of the piston 440 upon relative movement is unavoidable.

In order to solve the problem that the performance of the accumulator 40 is degraded by the leaked brake fluid, the method of promptly discharging the leaked brake fluid can be used. To this end, the accumulator 40 of the present application includes a bleed passage 499 configured to bleed brake fluid that has leaked from the high-pressure side of the piston 440 to the low-pressure side.

According to the first embodiment of the vehicle braking system in 1 is leaked brake fluid in a container in an atmospheric pressure environment, z. B. the brake fluid reservoir or any other container omitted. In this case, the bleed passage 499 extends through the cylinder 410 and leads to the outside of the accumulator 40, as in FIG 3 will be shown. In use, an external tubing is connected to the bleed passage 499, with another end of the external tubing leading to the container in the atmospheric pressure environment. The external tubing can be any suitable tubing commonly used in the art, e.g. B. a rigid hard metal tube, but is preferably a flexible non-metal tube, which can offer the advantages of portability and flexibility.

Optionally, according to the second embodiment of the vehicle brake system in 2 leaked brake fluid discharged into a vacuum environment. To this end, the bleed passage 499 may be configured to be connected to the main release line L2 via an inner tube formed inside the cylinder 410 of the accumulator 40 and/or an outer tube located outside the cylinder 410 of the accumulator 40 as described above, so that when the accumulator 40 discharges high-pressure brake fluid, brake fluid that has leaked to the low-pressure side of the piston 440 is sucked to the pump 50 at the same time. In this embodiment, the one-way valve 42 is as shown in FIG 2 required to prevent brake fluid from entering the piston chamber 430 from the low pressure side while allowing brake fluid to be exhausted from the low pressure side. In this situation, although not shown, the bleed passage 400 may be connected to the fluid passage 412 via a fluid passage within the cylinder 410 instead of penetrating the cylinder 410 .

In the present application, there are no limitations as to the quantity, shape, size, or location of the bleed passage 499.

Optionally, since the end cap 450 defines at least part of the piston chamber 430, in particular the low-pressure side of the piston 440, it is also possible for the discharge channel 499 to be arranged at a suitable position on the end cap 450. Furthermore, the bleed passage 499 of the accumulator 40 could also extend through both the cylinder 410 and the end cap 450 as long as it can direct brake fluid that has leaked from the low pressure side of the piston 440 to the exterior of the cylinder 410 .

According to the present application, the provision of the bleed passage 499 eliminates the need to machine a through hole for arranging a gas permeable component in the end cap 450 of the accumulator 40, thereby reducing the cost of machining and manufacturing the end cap 450, and there is no longer a need to provide a relatively expensive gas permeable component in the end cap 450.

The vehicle braking system of the present application has been described in detail above with reference to the specific embodiments shown in the drawings. In a situation where it is impossible to completely avoid accumulator leakage, the accumulator of the present application solves the task of directing leaked brake fluid out of the accumulator, thereby avoiding or even eliminating the technical problem of the leaked brake fluid affecting the performance of the accumulator can be. The leaked brake fluid can be directed to an atmospheric pressure environment or can be directed to a negative pressure environment, whereby the leaked brake fluid can be discharged more thoroughly.

It will also be apparent to those skilled in the art that the present application is not limited to the specific embodiments shown in the drawings and described above. Various replacements, changes and modifications are conceivable under the provided that the spirit and scope of the present application are not departed from.

Claims (13)

A vehicle braking system comprising an accumulator (40), the accumulator (40) comprising: a cylinder (410) having a first end portion defining a fluid passage (412); and an end cap (450) installed at a second end portion of the cylinder (410) and together with the cylinder (410) defines a piston chamber (430) in flow communication with the fluid passage (412); and a piston (440) received in the piston chamber (430) and capable of axial reciprocation therein, a resilient member (460) being clamped between the piston (440) and the end cap (450) and the piston chamber ( 430) is divided by the piston (440) into a high-pressure side which is in flow communication with the fluid passage (412) and a low-pressure side on which the elastic element (460) is positioned, the pressure accumulator (40) further having a discharge passage (499) configured to direct brake fluid that has leaked 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. vehicle braking system claim 1 wherein the bleed passage (499) is configured to direct leaked brake fluid to a reservoir positioned in an atmospheric pressure environment via an outer tube positioned outside of the cylinder (410). vehicle braking system claim 2 , wherein the outer tube is a rigid tube or a flexible tube. vehicle braking system claim 1 wherein the bleed passage (499) is configured to cause brake fluid that has leaked from the low-pressure side to flow through an outer tube positioned outside of the cylinder (410) and/or an inner tube extending inside the cylinder (410) and thereby enters a flow of brake fluid which is exhausted from the fluid passage (412). vehicle braking system claim 4 wherein a one-way valve that only allows leaked brake fluid to flow out of the low-pressure side but does not allow brake fluid to enter the low-pressure side is provided on the drain passage (499). vehicle braking system claim 5 , wherein the one-way valve has an opening pressure of approximately zero. Vehicle braking system according to any one of Claims 1 - 6 wherein the discharge passage (499) is formed in the cylinder (410) and/or the end cap (450). Vehicle braking system according to any one of Claims 1 - 7 wherein the end cap (450) of the accumulator (40) is a solid component. Vehicle braking system according to any one of Claims 1 - 8th , further comprising a first guide ring (480) and a second guide ring (490) which are arranged between the piston (440) and the cylinder (410) in the vicinity of the high pressure side and the low pressure side. vehicle braking system claim 9 wherein the first guide ring (480) and the second guide ring (490) are annular members having apertures. vehicle braking system claim 10 , wherein the first guide ring (480) or the second guide ring (490) is in engagement with an annular groove formed on an outer surface of the piston (440) facing the cylinder (410), and the respective other guide ring - the first or the second - engages with an annular groove formed on the outer surface of the piston (440) facing the cylinder (410) or with an annular groove formed on an inner surface of the cylinder (410), facing the piston (440), is engaged. Vehicle braking system according to any one of claims 9 - 11 Further comprising a seal member (470) disposed between the first guide ring and the second guide ring in an axial direction, wherein a seal groove (475) for receiving the seal member (470) is formed on an outer surface of the piston (440). Accumulator being the type used in the vehicle braking system according to any one of Claims 1 - 12 used accumulator (40) is.

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