Check valves for hydraulic non-human-powered vehicle brake equipment, and hydraulic non-human-powered vehicle brake equipment

Abstract

The present invention proposes to dispose a check valve (28) having a valve opening spring (29) between a pressureless brake fluid storage container (10) and a master brake cylinder (22) of a hydraulic non-human-powered vehicle brake equipment (1) having a non-human-powered brake pressure generator (3), which is capable of flowing in the direction of the master brake cylinder (22) and which blocks reverse flow from the master brake cylinder (22) to the brake fluid storage container (10) once the back pressure in the master brake cylinder (22) determined by the valve opening spring (29) has been exceeded.

Description

[Technical field]

[0001] The invention relates to a special check valve for hydraulic non-human-powered vehicle braking installations having the features of the preamble of claim 1 and to a hydraulic non-human-powered vehicle braking installation with such a check valve having the features of the preamble of claim 2. Claim 4 is directed to a variant of claim 2. [Background technology]

[0002] Springless and spring-loaded check valves are known, with the spring-loaded check valve only opening when an opening pressure defined by a valve closing spring is exceeded.

[0003] Patent Document 1 discloses a hydraulic non-human-powered vehicle braking system having a muscle-operable master brake cylinder, a non-human-powered brake pressure generator, and a brake fluid storage container to which the brake circuit of the master brake cylinder is connected by a solenoid valve that opens when the master brake cylinder is in the de-energized basic position. A check valve that allows flow in the direction of the master brake cylinder is hydraulically connected in parallel to the solenoid valve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Patent Application Publication No. 2012 / 150120A1 Brochure Summary of the Invention

[0005] The non-return valve according to the invention having the features of claim 1 is capable of flow in the through-flow direction in the same way as a springless non-return valve. Instead of a valve-closing spring, the non-return valve according to the invention has a valve-opening spring which keeps the non-return valve open in the closing direction opposite to the through-flow direction until a defined back pressure is reached, so that the non-return valve is capable of flow not only in the through-flow direction but also in the closing direction opposite to this, as long as the defined back pressure is not exceeded. The back pressure is a pressure acting in the closing direction of the non-return valve, which occurs between the valve outlet and the valve inlet, or generally between two connections of the non-return valve, and which closes the non-return valve according to the invention against the opening force of the valve-opening spring when this pressure exceeds a defined value. The non-return valve according to the invention therefore only closes in the closing direction opposite to the through-flow direction when a defined back pressure is exceeded. The defined back pressure can be fixed or adjustable, the back pressure being determined in particular by the valve-opening spring, but also by the geometry and the design of the non-return valve.

[0006] The hydraulic non-human vehicle brake installation according to the invention, which has the features of claim 2, comprises a muscle-operable master brake cylinder, a non-human brake pressure generator and in particular a pressureless brake fluid reservoir. The master brake cylinder may be operable by means of an auxiliary force, i.e. by means of a muscle force which is amplified by the auxiliary force of a brake booster. The brake circuit of the master brake cylinder is connected to the brake fluid reservoir by a non-return valve of the type described above. This non-return valve allows flow in the through-flow direction towards the master brake cylinder. In the opposite closing direction, flow can also pass through this non-return valve until a defined back pressure is reached. Only when the defined back pressure is exceeded, i.e. when the pressure on the master brake cylinder side of the non-return valve becomes higher than on the brake fluid reservoir side by more than the defined back pressure, does the non-return valve close against flow from the master brake cylinder towards the brake fluid reservoir. If the master brake cylinder has more than one brake circuit, the other brake circuits may not be connected to the brake fluid storage container, for example, or may be connected to the brake fluid storage container directly without a valve, or by means of a solenoid valve, or by means of a check valve not according to the invention, or by means of another valve not according to the invention.

[0007] The alternative according to claim 4 provides for a switchable test valve 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 under a defined overpressure at the master brake cylinder relative to the pressure at the brake fluid reservoir, so that when the defined overpressure at the master brake cylinder is reached or exceeded, brake fluid flows from the master brake cylinder to the brake fluid reservoir even when the test valve is closed. "Switchable" means that the test valve is switchable between a closed position and an open position.

[0008] All features disclosed in the specification and the drawings may be embodied in the respective embodiments of the invention, either alone or in principle in any combination. In principle, embodiments of the invention are also possible that have one or more features of the claims or embodiments of the invention, but not all features.

[0009] The invention will now be described in more detail with reference to the embodiments shown in the drawings. [Brief description of the drawings]

[0010] [Figure 1] 1 is a hydraulic circuit diagram of a hydraulic non-human-powered vehicle brake system according to the present invention, having a check valve according to the present invention. [Figure 2a] 1 is a switching diagram showing a check valve according to the invention in one switching position. [Figure 2b] 4A-4C are switching diagrams showing the check valve according to the invention in different switching positions; [Figure 2c] 4A-4C are switching diagrams showing the check valve according to the invention in different switching positions; [Diagram 3] FIG. 2 is a partial hydraulic circuit diagram of a modified embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The hydraulic non-powered vehicle brake installation 1 according to the invention is intended for a passenger vehicle having four hydraulic wheel brakes 2 and is implemented as a two-circuit brake installation with two hydraulic wheel brakes 2 per brake circuit. Other embodiments are possible, such as a one-circuit brake installation or a multi-circuit brake installation with more than two brake circuits and / or a different number of wheel brakes 2 and / or a different allocation of the wheel brakes 2 to the brake circuits.

[0012] The vehicle brake equipment 1 has an electrohydraulic non-human-powered brake pressure generator 3 with a piston-cylinder unit 5, whose piston 6 is axially slidable in a cylinder 9 by an electric motor 7 via a screw transmission 8 or other rotation-translation-conversion transmission for generating brake pressure. The piston-cylinder unit 5 can also be called a plunger unit, the piston 6 a plunger piston, and the cylinder 9 a plunger cylinder.

[0013] The cylinder 9 of the piston-cylinder unit 5 of the non-human brake pressure generator 3 is connected directly to the brake fluid storage container 10 by a brake line 26 and indirectly to the pressureless brake fluid storage container 10 by a non-return valve 27 through which brake fluid can be drawn in the direction of the cylinder 9 from the brake fluid storage container 10. The piston 6 of the piston-cylinder unit 5 crosses the brake line 26 at the beginning of its stroke, whereby this connection to the brake fluid storage container 10 is closed at the beginning of the stroke of the piston 6 of the piston-cylinder unit 5. Via the non-return valve 27, the cylinder 9 is always connected to the brake fluid storage container 10.

[0014] The wheel brakes 2 are connected to the non-human brake pressure generator 3, or more precisely to the cylinder 9 of the piston-cylinder unit 5 of the non-human brake pressure generator 3, via valves, here called non-human valves 11, a first separation valve 12 and a brake pressure control valve arrangement 13. For the division into both brake circuits, two non-human valves 11 are hydraulically arranged in parallel and two first separation valves 12 are hydraulically arranged in parallel as well, so that in each brake circuit one of both non-human valves 11 and one of both first separation valves 12 are hydraulically arranged in series. Two wheel brakes 2 are respectively connected to the non-human brake pressure generator 3 via one non-human valve 11 and one first separation valve 12 via the brake pressure control valve arrangement 13.

[0015] The brake pressure control valve arrangement 13 has for each wheel brake 2 an inlet valve 14 and a discharge valve 15. Via the inlet valves 14 the wheel brakes 2 are connected to the first separation valve 12, i.e. two wheel brakes 2 each with one inlet valve 14 in each brake circuit are connected to the first separation valve 12. Via the discharge valve 15 the wheel brakes 2 are connected to the brake fluid storage container 10.

[0016] The inlet valve 14 and the outlet valve 15 form a brake pressure control valve arrangement 13, by means of which the wheel brake pressure at each wheel brake 2 can be controlled individually. In cooperation with a hydropump 16, slip control is possible, in particular anti-lock control, traction control and / or vehicle dynamic control or electronic stability program, for which the abbreviations ABS, ASR and / or FDR or ESP are customarily used. Vehicle dynamic control or electronic stability program are also called skid control in everyday language. Such slip controls are well known and will not be described in detail here.

[0017] The vehicle brake installation 1 according to the invention has a two-circuit master brake cylinder 22 operable by a foot brake pedal 21 as a muscle brake pressure generator, to which the wheel brakes 2 of each brake circuit are connected via a second isolation valve 23, a first isolation valve 12 and an intake valve 14 of a brake pressure control valve arrangement 13, so that the vehicle brake installation 1 can also be operated by muscle force. The second isolation valve 23, the first isolation valve 12 and the intake valve 16 are hydraulically arranged in series. The two-circuit master brake cylinder 22 can have a brake booster (not shown) and can then be called an auxiliary brake pressure generator.

[0018] The suction side of the hydropump 16 is connected to the master brake cylinder 22 via an inlet valve 20, through which the hydropump 16 can draw brake fluid from the brake fluid reservoir 10. For each brake circuit there is a hydropump 16 which can be driven by a common electric motor 17. The pressure side of the hydropump 16 is connected to the wheel brake 2 via the first isolation valve 12 and the intake valve 14. The hydropump 16, which is housed in its own hydraulic block together with the inlet valve 20 and the second isolation valve 23, is used to generate brake pressure during slip control.

[0019] Basically, non-human operation of the vehicle brake system 1 is intended, whereby the brake pressure is generated by an electrohydraulic non-human brake pressure generator 3. In the event of a fault or failure of the electrohydraulic non-human brake pressure generator 3, brake pressure generation is possible by a slip-controlled hydropump 16 or alternatively by a master brake cylinder 22. The master brake cylinder 22 itself serves as a setpoint generator for the wheel brake pressure to be adjusted in the wheel brakes 2 in the presence of a functional electrohydraulic non-human brake pressure generator 3.

[0020] In one of both brake circuits, a pedal stroke simulator 24 is connected to the master brake cylinder 22 via a simulator valve 25. The pedal stroke simulator 24 is a spring-loaded hydraulic reservoir into which, when the simulator valve 25 is open, brake fluid can be displaced from the master brake cylinder 22 so that during unpowered braking when the second isolation valve 23 is closed, the piston of the master brake cylinder 22 is able to slide and the foot brake pedal 21 is movable to convey a normal pedal feel to the driver.

[0021] One of the two brake circuits of the master brake cylinder 22 is connected to the brake fluid reservoir 10 through an inventive check valve 28 with a valve opening spring 29. The other brake circuit is in this example connected directly to the brake fluid reservoir 10. Figures 2a to 2c show three different switching positions of the check valve 28. The check valve 28 allows flow in a through-flow direction from the brake fluid reservoir 10 to the master brake cylinder 22. In the opposite closing direction, the valve opening spring 29 keeps the check valve 28 open until a defined back pressure is reached. The back pressure is the pressure difference between the master brake cylinder 22 and the brake fluid reservoir 10 with the brake fluid reservoir 10 unpressurized, i.e. the pressure in the master brake cylinder 22. When the back pressure is exceeded, it counters the force of the valve opening spring 29 and closes the check valve 28 , thereby preventing brake fluid from flowing from the master brake cylinder 22 to the brake fluid reservoir 10 .

[0022] The back pressure required to close the check valve 28, which can also be understood as the overpressure of the master brake cylinder 22 relative to the unpressurized brake fluid reservoir 10 or relative to the pressure in the brake fluid reservoir 10, is determined by the valve release valve 29 and by the geometry and design of the check valve 28. The back pressure can be fixed or adjustable.

[0023] The non-return valve 28 is preceded by a filter 32 and followed by another filter 32, which means that a filter 32 is arranged between the brake fluid storage container 10 and the non-return valve 28, and a filter 32 is arranged between the check valve 28 and the master brake cylinder 22. An embodiment without a filter 32 or with only one filter is also possible, in which case the filter 32 is preferably arranged before the check valve 28 in the flow direction. A separate filter 32 can be used or one or more filters 32 are integrated into the check valve 28. Shown is a filter 32 integrated into the check valve 28 between the brake fluid storage container 10 and the check valve 28, and a filter 32 separate from the check valve 28 between the check valve 28 and the master brake cylinder 22.

[0024] For (initial) filling, the non-powered vehicle brake equipment 1 is first evacuated and subsequently filled with brake fluid by the brake fluid reservoir 10. When evacuating, a valve opening spring 29 keeps the check valve 28 open between the brake fluid reservoir 10 and the master brake cylinder 22, as shown in Figure 2a. When filling with brake fluid, the check valve 28 possibly continues to be open, as shown in Figure 2c.

[0025] To test the functionality of the non-human brake pressure generator 3, when hydraulic brake pressure is generated by the non-human brake pressure generator 3, the generated brake pressure is transmitted to the master brake cylinder 22 when the non-human valve 11 is open under the open second isolation valve 23. If the brake pressure in the master brake cylinder 22 exceeds the defined back pressure of the non-return valve 28, it is closed, thereby preventing the flow of brake fluid through the master brake cylinder 22 to the brake fluid storage container 10. The functionality of the non-human brake pressure generator 3, the compressibility of the brake fluid possibly due to air bubbles, and the functionality of the valves of the vehicle brake installation 1 can be tested.

[0026] To check the functionality of the non-human brake pressure generator 3, the non-human valve 11 of a brake circuit that does not have a check valve 28 according to the invention is kept closed or the second isolation valve 23 of this brake circuit is closed so that the brake fluid of this brake circuit does not flow through the master brake cylinder 22 to the brake fluid storage container 10.

[0027] Figure 3 shows a part of the hydraulic circuit diagram from Figure 1 in the region of the brake fluid reservoir 10 and the master brake cylinder 22. As in Figure 1, in Figure 3 too a check valve 30 is arranged between the brake fluid reservoir 10 and the master brake cylinder 22, through which flow can pass from the brake fluid reservoir 10 to the master brake cylinder 22 in the through-flow direction and which is blocked from passing in the opposite closing direction. A test valve 31 is hydraulically connected in parallel to the check valve 30, which in this example is an electromagnetic valve, i.e. a switchable valve, which when open connects the master brake cylinder 22 with 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.

[0028] The test valve 31 is made such that when it is closed, it opens under a defined overpressure in the master brake cylinder 22. This overpressure is a pressure in the master brake cylinder 22 higher than the brake fluid reservoir 10, which in this embodiment is unpressurized. The overpressure may be fixed or adjustable. The test valve 31 avoids a pressure higher than the defined overpressure in the vehicle brake installation 1 when the master brake cylinder 22 is not actuated.

[0029] A test of the functionality of the non-human brake pressure generator 3, as described above for Fig. 1, is likewise possible in Fig. 3 by closing the test valve 31, the test pressure then being limited to a defined overpressure above which the test valve 31 opens as long as the master brake cylinder 22 is not actuated. For example, brake fluid previously sucked from the brake fluid reservoir 10 by the non-human brake pressure generator 3 can flow back to the brake fluid reservoir 10 through the master brake cylinder 22 and the test valve 31.

[0030] The check valve 30 is of the springless type and is integrated into the test valve 31, thereby not requiring additional design space.

[0031] A further check valve 33 is hydraulically connected in parallel to the check valve 30 and the test valve 31, which reduces the flow resistance of the brake fluid from the brake fluid storage container 10 to the master brake cylinder 22, which is a significant advantage when sucking brake fluid with the hydropump 12 in the event of a failure of the non-human brake pressure generator 3. Since the additional check valve 33 is not integrated in the test valve 31, it can have an even larger flow cross section and a lower flow resistance.

[0032] In FIG. 3, a filter 32 integrated in the test valve 31 is also arranged upstream and downstream of the non-return valve 30 and the test valve 31, i.e. one filter 32 is arranged between the brake fluid reservoir 10 on the one hand and the non-return valve 30 and the test valve 31 on the other hand, and one filter 32 is arranged 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 non-return valve 34 is provided between the brake fluid reservoir 10 and the further non-return valve 33. No filter is provided between the further non-return valve 33 and the master brake cylinder 22, since the further non-return valve 33 provides a shield against throughflow from the master brake cylinder 22 in the direction towards the brake fluid reservoir 10, i.e. no brake fluid that would have to be filtered flows from the master brake cylinder 22 to the further non-return valve 33. The flow resistance of the check valve 33 to the flow through from the brake fluid reservoir 10 to the master brake cylinder 22 is lower with only one filter 33 than with two filters.

[0033] In other respects, the vehicle braking equipment 1 shown in Figures 1 and 3 are identical and function in a similar manner, so that Figure 1 can be used to complete the circuit diagram of Figure 3 and the description of Figure 1 can be used to complete the description of Figure 3.

[0034] In the embodiment of the invention described and shown, the non-powered valve 11, the first isolation valve 12, the intake valve 16, the discharge valve 17, the suction valve 20, the second isolation valve 23, the simulator valve 25 and the test valve 31 are 2 / 2-way solenoid valves, with the first isolation valve 12, the intake valve 16, the second isolation valve 23 and the test valve 31 being open in their de-energized basic positions, and the non-powered valve 11, the discharge valve 17, the suction valve 20 and the simulator valve 25 being closed in their de-energized basic positions. Other embodiments and / or switching positions of the valves are not excluded. For example, the intake valve 14 and the discharge valve 15 could be combined into a 3 / 2 solenoid valve (not shown). [Explanation of symbols]

[0035] 1. Hydraulic non-human powered vehicle brake equipment 3. Non-human brake pressure generator 10 Brake fluid storage container 16 Hydro Pump 22 Master brake cylinder 28 Check valve 29 Valve opening spring 30 Check valve 31 Test valve

Claims

1. 1. A check valve for a hydraulic non-human-powered vehicle brake system (1), for arrangement between a brake fluid storage container (10) and a master brake cylinder (22), through which a flow can flow in a through-flow direction, characterized in that the check valve (28) has a valve opening spring (29) that keeps the check valve (28) open in a closing direction opposite to the through-flow direction until a defined back pressure is reached and that is arranged on the closing direction side of a valve seat of the check valve (28), whereby the check valve (28) closes in the closing direction only after the defined back pressure is exceeded.

2. 1. A hydraulic non-human-powered vehicle brake system comprising a muscle-operable master brake cylinder (22), a non-human-powered brake pressure generator (3) and a brake fluid storage container (10), characterized in that the master brake cylinder (22) is connected to the brake fluid storage container (10) through a check valve (28), which allows a flow of brake fluid to pass through the brake fluid storage container (10) from the master brake cylinder (22) in a through-flow direction, and which has a valve opening spring (29) that keeps the check valve (28) open in a closing direction opposite to the through-flow direction until a defined back pressure is reached and is arranged on the closing direction side of a valve seat of the check valve (28), whereby the check valve (28) closes in the closing direction only after the defined back pressure is exceeded.

3. 3. A hydraulic non-human-powered vehicle brake installation according to claim 2, characterized in that the non-return valve (28) is preceded and / or followed by a filter (32).

4. 3. The hydraulic non-human-powered vehicle brake equipment according to claim 2, characterized in that the vehicle brake equipment (1) has a hydropump (16) that can be driven by a non-human power, and the vehicle brake equipment (1) can be operated by the hydropump when a fault or failure occurs in the non-human-powered brake pressure generator (3).

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