Check valve for hydraulically assisted vehicle brake equipment and hydraulically assisted vehicle brake equipment

Abstract

The present invention proposes that a check valve (28) with a valve opening spring (29) is arranged between a non-pressurized brake fluid storage container (10) and a master brake cylinder (22) of a hydraulically assisted vehicle brake system (1) having a assisted brake pressure generator (3), wherein the check valve allows flow in the direction of the master brake cylinder (22) and blocks a backflow from the master brake cylinder (22) into the brake fluid storage container (10) due to a counterpressure in the master brake cylinder (22) determined by the valve opening spring (29).

Description

Technical Field

[0001] The invention relates to a special non-return valve for a hydraulically assisted vehicle brake system and a hydraulically assisted vehicle brake system having such a non-return valve. Background Art

[0002] Spring-free and spring-loaded check valves are known, wherein the spring-loaded check valve does not open until an opening pressure determined by a valve closing spring is exceeded.

[0003] International patent application WO 2012 / 150 120 A1 discloses a hydraulically assisted vehicle brake system having a manually operable master brake cylinder, a assisted brake pressure generator, and a brake fluid reservoir. The brake circuit of the master brake cylinder is connected to the brake fluid reservoir via a solenoid valve that is open in its zero-flow initial position. A check valve, through which flow is allowed toward the master brake cylinder, is hydraulically connected in parallel to the solenoid valve. Summary of the Invention

[0004] The check valve according to the present invention allows flow in the through-flow direction, just like a springless check valve. Instead of a valve closing spring, the check valve according to the present invention has a valve opening spring that holds the check valve open until a defined counterpressure in a closing direction opposite to the through-flow direction is reached. This allows flow not only in the through-flow direction but also in the opposite closing direction, as long as the defined counterpressure is not exceeded. The counterpressure is a pressure acting in the closing direction of the check valve between the valve outlet and the valve inlet, or generally between the two connections of the check valve, and when this pressure exceeds a defined value, it closes the check valve according to the present invention against the opening force of the valve opening spring. The check valve according to the present invention closes to prevent flow in the closing direction, i.e., only when a defined counterpressure is exceeded. The defined counterpressure can be fixed or adjustable and is determined, in particular, by the valve opening spring or by the geometry and design of the check valve.

[0005] A hydraulically assisted vehicle brake system according to the present invention comprises a manually operable master brake cylinder, a booster brake pressure generator, and a, in particular, unpressurized, brake fluid reservoir. The master brake cylinder can also be actuated with boosting, i.e., manually amplified, by the boosting of a brake pressure booster. The brake circuit of the master brake cylinder is connected to the brake fluid reservoir via a check valve of the type described above. The check valve allows flow in the flow direction toward the master brake cylinder. In the opposite closing direction, the check valve also allows flow until a certain counterpressure is reached. The check valve closes to prevent flow from the master brake cylinder toward the brake fluid reservoir only when the certain counterpressure is exceeded—i.e., when the pressure on the master brake cylinder side of the check valve is greater than on the brake fluid reservoir side by more than the certain counterpressure. If the master brake cylinder has more than one brake circuit, the additional brake circuits can, for example, be connected to the brake fluid reservoir without a valve, and then connected to the brake fluid reservoir via a solenoid valve, a check valve not according to the present invention, or another valve not according to the present invention.

[0006] The alternative described in the present invention provides for a switchable test valve that is hydraulically connected in parallel to the check valve. The check valve is preferably a standard check valve with or without a valve closing spring. The test valve opens at a defined overpressure in the master brake cylinder relative to the pressure in the brake fluid reservoir. Thus, even when the defined overpressure in the master brake cylinder is reached or exceeded, brake fluid flows from the master brake cylinder into the brake fluid reservoir with the test valve closed. "Switchable" means that the test valve can be switched between a closed and an open position.

[0007] All features disclosed in the description and drawings can be implemented in embodiments of the invention individually or in any combination in principle. Embodiments of the invention that do not have all features of the embodiments of the invention, but only have one or more features, are in principle possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present invention is explained in more detail below based on the embodiments shown in the accompanying drawings, in which:

[0009] Figure 1 Shows a hydraulic circuit diagram of a hydraulically assisted vehicle brake system according to the invention with a check valve according to the invention;

[0010] Figure 2a -c shows the switching markings of the non-return valve according to the present invention in three switching positions; and

[0011] Figure 3 A portion of a hydraulic circuit diagram showing a modified embodiment of the present invention is shown. DETAILED DESCRIPTION

[0012] The hydraulically assisted vehicle brake system 1 according to the invention is provided for a passenger vehicle having four hydraulic wheel brakes 2 and is designed as a dual-circuit brake system having two hydraulic wheel brakes 2 per brake circuit. Other embodiments are possible, for example single-circuit brake systems or multi-circuit brake systems having more than two brake circuits and / or a different number of wheel brakes 2 and / or a different allocation of wheel brakes 2 to the brake circuits.

[0013] Vehicle brake system 1 has an electrohydraulic booster brake pressure generator 3 with a piston-cylinder unit 5, whose piston 6 can be displaced axially in a cylinder 9 by means of an electric motor 7 via a screw drive 8 or other rotation-translation conversion drive for generating brake pressure. The piston-cylinder unit 5 can also be referred to as a plunger unit, its piston 6 as a plunger piston, and its cylinder 9 as a plunger cylinder.

[0014] Cylinder 9 of piston-cylinder unit 5 of booster brake pressure generator 3 is connected directly to brake fluid reservoir 10 via brake line 26 and indirectly to unpressurized brake fluid reservoir 10 via a non-return valve 27 through which flow can flow toward cylinder 9 , so that brake fluid can be drawn from brake fluid reservoir 10. At the beginning of its stroke, piston 6 of piston-cylinder unit 5 passes through brake line 26, thereby closing this connection to brake fluid reservoir 10 at the beginning of the stroke of piston 6 of piston-cylinder unit 5. Cylinder 9 is always connected to brake fluid reservoir 10 via non-return valve 27.

[0015] Wheel brakes 2 are connected to a booster brake pressure generator 3, specifically, to cylinders 9 of piston-cylinder unit 5 of booster brake pressure generator 3, via valves (referred to herein as booster valves 11), first isolating valves 12, and a brake pressure control valve system 13. To separate into two brake circuits, two booster valves 11 are hydraulically connected in parallel, two first isolating valves 12 are also hydraulically connected in parallel, and one of the two booster valves 11 and one of the two first isolating valves 12 are hydraulically arranged in series in each brake circuit. Via brake pressure control valve system 13, both wheel brakes 2 are connected to booster brake pressure generator 3 via booster valves 11 and first isolating valves 12, respectively.

[0016] Brake pressure regulating valve system 13 has an inlet valve 14 and an outlet valve 15 for each wheel brake 2. Wheel brakes 2 are connected to first isolating valve 12 via inlet valves 14, more precisely, two wheel brakes 2 in each brake circuit are connected to first isolating valve 12 via one inlet valve 14 each. Wheel brakes 2 are connected to brake fluid reservoir 10 via outlet valves 15.

[0017] Inlet valve 14 and outlet valve 15 form a brake pressure control valve system 13, which allows the wheel brake pressure in each wheel brake 2 to be individually adjusted. Together with a hydraulic pump 16, slip control can be implemented, particularly anti-lock braking control, drive slip control, and / or driving dynamics control or an electronic stability program. These slip control systems are often referred to by the abbreviations ABS, ASR, and / or FDR, or ESP. Driving dynamics control and electronic stability programs are also colloquially referred to as anti-slip control mechanisms. Such slip control is well known and will not be explained in detail here.

[0018] The vehicle brake system 1 according to the present invention includes a dual-circuit master brake cylinder 22 as a manual brake pressure generator, which can be operated using a foot brake pedal 21. The wheel brakes 2 in each brake circuit are connected to the dual-circuit master brake cylinder via a respective second isolating valve 23, a first isolating valve 12, and an inlet valve 14 of a brake pressure regulating valve system 13. This allows manual actuation of the vehicle brake system 1. The second isolating valve 23, the first isolating valve 12, and the inlet valve 16 are arranged hydraulically in series. The dual-circuit master brake cylinder 22 can include a brake force booster (not shown) and is therefore referred to as a booster brake pressure generator.

[0019] The suction side of the hydraulic pump 16 is connected to the master brake cylinder 22 via a suction valve 20 , allowing the hydraulic pump 16 to draw brake fluid from the brake fluid reservoir 10 via the master brake cylinder. A hydraulic pump 16 is provided for each brake circuit and can be driven by a common electric motor 17 . The pressure side of the hydraulic pump 16 is connected to the wheel brakes 2 via a first isolating valve 12 and an inlet valve 14 . The hydraulic pump 16 , along with the suction valve 20 and the second isolating valve 23 , is housed in its own hydraulic block and is used to generate brake pressure during slip control.

[0020] In principle, vehicle brake system 1 is actuated via power assistance, with brake pressure being generated by electro-hydraulic power-assisted brake pressure generator 3. In the event of a malfunction or failure of electro-hydraulic power-assisted brake pressure generator 3, brake pressure generation can be accomplished using hydraulic pump 16 of the slip control mechanism or, alternatively, master brake cylinder 22. Master brake cylinder 22 itself serves as a target value transmitter for the wheel brake pressure to be set in wheel brakes 2 when electro-hydraulic power-assisted brake pressure generator 3 is operational.

[0021] In one of the two brake circuits, a pedal travel simulator 24 is connected to the master brake cylinder 22 via a simulator valve 25. The pedal travel simulator 24 is a spring-loaded hydraulic accumulator. When the simulator valve 25 is open, brake fluid can be discharged from the master brake cylinder 22. As a result, during power-assisted braking—with the second isolating valve 23 closed—a piston can be displaced in the master brake cylinder 22 and the foot brake pedal 21 can be moved, so that the vehicle driver can achieve the pedal feel he is accustomed to.

[0022] One of the two brake circuits of master brake cylinder 22 is connected to brake fluid reservoir 10 via a nonreturn valve 28 according to the invention having a valve opening spring 29. The other brake circuit is connected directly to brake fluid reservoir 10 in the exemplary embodiment. Figure 2a Figures c to c show three different switching positions of the check valve 28. The check valve 28 allows flow in the flow direction from the brake fluid reservoir 10 toward the master brake cylinder 22. In the opposite closing direction, the valve opening spring 29 holds the check valve 28 open until a certain counterpressure is reached. This counterpressure is the pressure difference between the master brake cylinder 22 and the brake fluid reservoir 10; when the brake fluid reservoir 10 is unpressurized, it is the pressure in the master brake cylinder 22. If the counterpressure is exceeded, it closes the check valve 28 against the spring force of the valve opening spring 29, so that brake fluid can no longer flow from the master brake cylinder 22 into the brake fluid reservoir 10.

[0023] The counterpressure, which is determined by the valve opening spring 29 and the geometry and design of the non-return valve 28, can also be understood as the overpressure in the master brake cylinder 22, with respect to the unpressurized brake fluid reservoir 10 or the pressure in the brake fluid reservoir 10 required to close the non-return valve 28. The counterpressure can be fixed or adjustable.

[0024] A filter 32 is arranged upstream of the check valve 28, and another filter 32 is arranged downstream. This means that the filter 32 is arranged between the brake fluid reservoir 10 and the check valve 28, and the filter 32 is arranged between the check valve 23 and the master brake cylinder 22. Embodiments without or with only one filter 32 are also possible, wherein the filter 32 is to be arranged upstream of the check valve 28 in the direction of flow. A separate filter 32 can be used, or the filter(s) 32 can be integrated into the check valve 28. The diagram shows a filter 32 integrated into the check valve 28 between the brake fluid reservoir 10 and the check valve 28, and a filter 32 separate from the check valve 28 between the check valve 23 and the master brake cylinder 22.

[0025] For (first-time) filling, the power-assisted vehicle brake system 1 is first evacuated and then filled with brake fluid via the brake fluid reservoir 10. During evacuation, the valve opening spring 29 holds the non-return valve 28 between the brake fluid reservoir 10 and the master brake cylinder 22 open. Figure 2a When injecting brake fluid, the check valve 28 continues to open if necessary, as shown. Figure 2c As shown.

[0026] If hydraulic brake pressure is generated by booster brake pressure generator 3 to test its functionality, then when booster valve 11 is opened while second isolating valve 23 is open, the generated brake pressure flows into master brake cylinder 22. If the brake pressure in master brake cylinder 22 exceeds a specific counterpressure of check valve 28, the check valve closes, so that brake fluid can no longer flow through master brake cylinder 22 into brake fluid reservoir 10. The functionality of booster brake pressure generator 3, any compressibility of the brake fluid due to cavitation, and the functionality of the valves of vehicle brake system 1 can be tested.

[0027] In order to check the functionality of the booster brake pressure generator 3 , the booster valve 11 of the brake circuit that does not have the non-return valve 28 according to the invention is kept closed, or the second isolating valve 23 of this brake circuit is closed, so that no brake fluid flows in this brake circuit via the master brake cylinder 22 into the brake fluid storage tank 10 .

[0028] Figure 3 Shown from Figure 1 A portion of the hydraulic circuit diagram in the area of ​​the brake fluid storage container 10 and the master brake cylinder 22. Figure 1 Like in Figure 3 A check valve 30 is also arranged between the brake fluid reservoir 10 and the master brake cylinder 22. This check valve allows flow in the flow direction from the brake fluid reservoir 10 to the master brake cylinder 22 and blocks flow in the opposite, closing direction. Hydraulically connected in parallel to the check valve 30 is a test valve 31, which in the present embodiment is a solenoid valve, that is, a switchable valve, which, when open, connects the master brake cylinder 22 to the brake fluid reservoir 10 in the brake circuit and, when closed, hydraulically isolates the master brake cylinder 22 from the brake fluid reservoir 10.

[0029] Test valve 31 is designed so that, when closed, it opens at a defined overpressure in master brake cylinder 22. In the master brake cylinder 22, the overpressure is a higher pressure than in the unpressurized brake fluid reservoir 10 in the present exemplary embodiment. The overpressure can remain unchanged or be adjustable. Test valve 31 prevents pressures exceeding the defined overpressure in vehicle brake system 1 without actuating master brake cylinder 22.

[0030] The above description of the functionality of the power-brake pressure generator 3 Figure 1 The test described in Figure 3 It is also possible to close test valve 31, limiting the test pressure to a certain overpressure, above which test valve 31 opens as long as master brake cylinder 22 is not actuated. For example, brake fluid previously drawn from brake fluid reservoir 10 by booster brake pressure generator 3 can flow back into brake fluid reservoir 10 via master brake cylinder 22 and test valve 31.

[0031] The non-return valve 30 is spring-free and integrated into the test valve 31 , so that no additional installation space is required.

[0032] An additional check valve 33 is connected hydraulically in parallel to the check valve 30 and the test valve 31. This additional check valve reduces the flow resistance for the brake fluid from the brake fluid reservoir 10 into the master brake cylinder 22. This is a significant advantage when the hydraulic pump 12 draws the brake fluid in the event of a failure of the booster brake pressure generator 3. Because the additional check valve 33 is not integrated into the test valve 31, it can have a larger flow cross section and a lower flow resistance.

[0033] exist Figure 3 Filters 32 are also arranged upstream and downstream of the check valve 30 and the test valve 31, and are integrated into the test valve 31. Specifically, the filter 32 is arranged between the brake fluid reservoir 10 on the one hand and the check valve 30 and the test valve 31 on the other hand, and between the check valve 30 and the test valve 31 on the one hand and the master brake cylinder 22 on the other hand. A further check valve 34 is arranged between the brake fluid reservoir 10 and a further check valve 33. No filter is arranged between the further check valve 33 and the master brake cylinder 22 because the further check valve 33 blocks the flow from the master brake cylinder 22 toward the brake fluid reservoir 10. In other words, brake fluid that needs to be filtered does not flow from the master brake cylinder 22 into the further check valve 33. The flow resistance to the flow from the brake fluid reservoir 10 to the master brake cylinder 22 through the check valve 33 is lower when only one filter 33 is provided than when two filters are provided.

[0034] besides, Figure 1 and Figure 3 The vehicle brake equipment 1 is consistent and works in the same way, so as to improve the Figure 3 The wiring diagram can be found in Figure 1 And in order to perfect Figure 3 For an explanation of Figure 1 explanation.

[0035] In the described and illustrated embodiment of the present invention, the power assist valve 11, the first separating valve 12, the inlet valve 16, the outlet valve 17, the suction valve 20, the second separating valve 23, the simulator valve 25, and the test valve 31 are 2 / 2-way solenoid valves. In their zero-flow initial position, the first separating valve 12, the inlet valve 16, the second separating valve 23, and the test valve 31 are open, while the power assist valve 11, the outlet valve 17, the suction valve 20, and the simulator valve 25 are closed. Other valve embodiments and / or switching positions are not excluded. For example, combining the inlet valve 14 and the outlet valve 15 into a 3 / 2-way solenoid valve is also possible (not shown).

Claims

1. A check valve for a hydraulically assisted vehicle brake system (1), the check valve being arranged between a brake fluid storage container (10) and a master brake cylinder (22), the check valve being capable of flow in a flow direction, and characterized in that: The non-return valve (28) has a valve opening spring (29) which is arranged on the closing direction side of the valve seat of the non-return valve (28) and which holds the non-return valve (28) open until a certain counterpressure in a closing direction arranged opposite to the throughflow direction is reached, so that the non-return valve (28) does not close until the certain counterpressure in the closing direction is exceeded.

2. A hydraulically assisted vehicle brake system comprising a manually operable master brake cylinder (22), a assisted brake pressure generator (3) and a brake fluid reservoir (10), characterized in that: The master brake cylinder (22) is connected to the brake fluid storage container (10) via a non-return valve (28), which is capable of flow in a flow direction from the brake fluid storage container (10) to the master brake cylinder (22), and has a valve opening spring (29), which is arranged on the closing direction side of the valve seat of the non-return valve (28) and keeps the non-return valve (28) open until a certain counter-pressure in a closing direction opposite to the flow direction is reached, so that the non-return valve (28) is closed only after the certain counter-pressure in the closing direction is exceeded.

3. The hydraulic power-assisted vehicle brake equipment according to claim 2, characterized in that: A filter is placed before and / or after the check valve (28).

4. The hydraulic power-assisted vehicle brake equipment according to claim 2, characterized in that: The hydraulically assisted vehicle brake system (1) has a hydraulic pump (16) that can be driven by an assisting force, and the hydraulically assisted vehicle brake system (1) can be actuated by means of the hydraulic pump in the event of an error or failure of the assisting brake pressure generator (3).

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