阅读说明：本技术 具有至少两个液压回路和至少两个压力供应装置的液压系统 (Hydraulic system with at least two hydraulic circuits and at least two pressure supply devices ) 是由 海因茨·莱贝尔 于 2020-02-12 设计创作，主要内容包括：本发明涉及一种用于车辆的制动系统,具有下述部件：两个液压制动回路(BK1、BK2),每个液压制动回路包括至少一个液压操作的轮制动器(RB1、RB2、RB3、RB4)；用于向轮制动器(RB1、RB2、RB3、RB4)供应压力的第一和第二压力供应装置(DV1、DV2)；具有用于单独地调节每个轮的制动压力和/或将轮制动器(RB1、RB2、RB3、RB4)与两个压力供应装置(DV1、DV2)中的至少一个分开或连接的阀的至少一个阀组件(HCU)；至少一个电子控制与调节单元(ECU)；以及连接两个制动回路(BK1、BK2)的液压连接管路(VL),其中,每个轮制动器(RB1、RB2、RB3、RB4)与专用的开关阀(SV)配对,并且每个制动回路(BK1、BK2)具有液压主管路(4、5),开关阀(SV)经由该液压主管路连接或能够连接至压力供应装置(DV1、DV2)。在连接管路(VL)中布置有串联连接且在不通电状态下打开的两个连接开关阀(BP1、BP2),并且连接开关阀(BP1、BP2)布置成在不通电状态下以由存在于各个液压主管路(4、5)和/或连接管路(VL)的内部部段(VLa)中的压力支持的方式打开,将连接开关阀(BP1、BP2)的两个连接部直接连接在一起的所述内部部段经由附加液压管路(3)连接至主缸(HZ)的压力室(A1)。在附加液压管路(3)中布置有至少一个阀(FV)以选择性地阻断所述液压管路。(The invention relates to a brake system for a vehicle, comprising the following components: two hydraulic brake circuits (BK1, BK2), each comprising at least one hydraulically operated wheel brake (RB1, RB2, RB3, RB 4); first and second pressure supply means (DV1, DV2) for supplying pressure to the wheel brakes (RB1, RB2, RB3, RB 4); at least one valve assembly (HCU) having valves for individually regulating the brake pressure of each wheel and/or separating or connecting the wheel brakes (RB1, RB2, RB3, RB4) from at least one of the two pressure supply devices (DV1, DV 2); at least one electronic control and regulation unit (ECU); and a hydraulic connecting line (VL) connecting the two brake circuits (BK1, BK2), wherein each wheel brake (RB1, RB2, RB3, RB4) is paired with a dedicated Switching Valve (SV), and each brake circuit (BK1, BK2) has a hydraulic main line (4, 5) via which the Switching Valve (SV) is connected or connectable to a pressure supply (DV1, DV 2). Two connection switching valves (BP1, BP2) which are connected in series and open in the non-energized state are arranged in the connecting line (VL), and the connection switching valves (BP1, BP2) are arranged to open in the non-energized state supported by the pressure prevailing in the respective hydraulic main line (4, 5) and/or in an inner section (VLa) of the connecting line (VL), which inner section directly connects together the two connections of the connection switching valves (BP1, BP2) is connected to the pressure chamber (A1) of the master cylinder (HZ) via an additional hydraulic line (3). At least one valve (FV) is arranged in the additional hydraulic line (3) to selectively block said hydraulic line.)

1. A braking system for a vehicle, the braking system having the following components:

two hydraulic brake circuits (BK1, BK2), each of which (BK1, BK2) has at least one hydraulically acting wheel brake (RB1, RB2, RB3, RB4),

-a first pressure supply device (DV1) and a second pressure supply device (DV2) for supplying pressure to the wheel brakes (RB1, RB2, RB3, RB4),

-at least one valve assembly (HCU) having a brake pressure for a wheel specific setting and/or a valve isolating or connecting the wheel brake (RB1, RB2, RB3, RB4) from or to at least one pressure supply device (DV1, DV2),

-at least one electronic open and closed loop control unit,

a hydraulic connecting line (VL) for connecting the two brake circuits (BK1, BK2),

-each wheel brake (RB1, RB2, RB3, RB4) is assigned in each case one dedicated Switching Valve (SV), and each brake circuit (BK1, BK2) has a hydraulic main line (4, 5), via which hydraulic main line (4, 5) the Switching Valve (SV) is connected or connectable to a pressure supply (DV1, DV2),

characterized in that two series-connected connecting switching valves (BP1, BP2) which open when de-energized are arranged in the connecting line (VL), wherein,

the connection switching valves (BP1, BP2) are arranged in such a way that in the power-off state the connection switching valves (BP1, BP2) open in a manner assisted by the pressure prevailing in the respective hydraulic main lines (4, 5) and/or

-the inner section (VLa) of the connecting line (VL) which directly connects the two connections of the connecting switching valves (BP1, BP2) to each other is connected to the pressure chamber (a1) of the master brake cylinder (HZ) via a further hydraulic line (3), wherein at least one valve (FV) is arranged in the further hydraulic line (3) for selectively closing the further hydraulic line (3).

2. A brake system according to claim 1, characterized in that it has a master brake cylinder (HZ) which can be actuated by an actuating unit (1), the actuating unit (1) in particular being in the form of a brake pedal, one pressure chamber (A1) of which is connected to a travel simulator (WS) and can be connected to at least one hydraulic brake circuit (BK1, BK 2).

3. A brake system according to claim 1 or 2, characterized in that the connection switch valve (BP1, BP2) is a 2/2-way valve and/or the valve connection assigned to the valve seat of the connection switch valve (BP1, BP2) is hydraulically connected to the hydraulic main line (4, 5).

4. A brake system according to any one of claims 1-3, characterized in that the internal connection line (VLa) is connected to a reservoir (VB) by means of a hydraulic line (6), and in that a non-return valve (RV in fig. 4) or a switching valve (ZAV) is arranged in the further hydraulic line (100).

5. A braking system according to claim 4, characterized in that the on-off valve (ZAV) has a diameter of less than 1mm²Preferably less than 0.7mm²Of the flow cross section.

6. A braking system according to any one of claims 1 to 5, characterized in that the connection switch valve (BP1, BP2) has a diameter greater than 1.5mm²Of the flow cross section.

7. A braking system according to any one of claims 4 to 6, characterized in that said check valve (SV) blocks in the direction of said reservoir (VB) and has a value greater than 2mm²Preferably greater than 3mm²Of the flow cross section.

8. A braking system according to any one of claims 1 to 7, characterized in that the first pressure supply (DV1) is an electrically driven piston-cylinder unit and the second pressure supply (DV2) is a pump with continuous delivery action, in particular in the form of a piston pump, gear pump or eccentric piston pump, driven by an electric drive (M).

9. A brake system according to claim 8, characterized in that the first pressure supply device (DV1) and the second pressure supply device (DV2) are designed for different maximum pressures (P1, P2) or pressure levels, and that two series-connected switching valves (BP1, BP2) which open when de-energized are arranged in the connecting line (VL).

10. A braking system according to any one of the foregoing claims, characterised in that the second pressure supply device (DV2) assists a further pressure supply device (DV1) in the event of a rapid pressure rise or pressure rise above the maximum pressure of the first pressure supply device, in particular above 120 bar, and/or that the second pressure supply device (DV2) performs a pressure supply in the event of a pressure drop and/or for ABS functions, and/or that the second pressure supply device (DV2) performs the function of the further pressure supply device (DV1) jointly in the event of a failure of the further pressure supply device (DV 1).

11. Braking system according to claim 9 or 10, characterized in that the pressure supply device (DV1) performs a pressure increase for a pressure range which is smaller than or equal to the maximum pressure (P1) of the pressure supply device (DV1), which maximum pressure (P1) is in particular 120 bar, and for ABS functions.

12. A braking system according to any one of the foregoing claims, characterised in that in the event of failure of the pressure supply device (DV2), only the maximum pressure (P1) of the pressure supply (DV1) is available.

13. A brake system according to any one of the foregoing claims, characterised in that one of the two pressure supply devices (DV1, DV2) is connected by its pressure side to the inner section (VLa) of the connecting line (VL) via a hydraulic line () in which the connecting switch valve (BP1, BP2) is not arranged.

14. A braking system according to claim 13, characterized in that at least one check valve (RV1, RV2) is arranged in the hydraulic line ().

15. A braking system according to any one of the preceding claims, characterized in that in the event of failure of one pressure supply device (DV1, DV2), the still functioning other pressure supply device (DV1, DV2) performs closed-loop pressure control and/or pressure supply in both brake circuits (BK1, BK2), in particular in both brake circuits (BK1, BK2) for ABS, ESP and/or recuperation, wherein pressure changes in the components (RB1, RB2, RB3, RB4) for ABS and/or ESP functions are performed continuously, i.e. consecutively and/or simultaneously by means of the valve assembly (HCU) in at least one brake circuit and at least one pressure supply device (DV1, DV 2).

16. A braking system according to any one of the foregoing claims, characterised in that at least one hydraulic main line (4, 5), in particular a hydraulic main line leading to front wheel brakes, is connected or connectable to a reservoir (VB) via a drain valve (AV1, AV2) and/or that the inner section (VLa) of the connecting line (VLa) is connected or connectable to a reservoir (VB) via a central drain valve (ZAV) for pressure reduction (P) in at least one wheel brake (RB1, RB2, RB3, RB4) and/or two brake circuits (BK1, BK2)_Reduce)。

17. A brake system according to any one of the foregoing claims, characterized in that the master brake cylinder (HZ) is a single master brake cylinder having only a single pressure chamber (A1) or a tandem master brake cylinder (THZ) having at least two pistons.

18. A braking system according to any one of the foregoing claims, characterised in that the pressure regulation in the wheel brakes (RB1, RB2, RB3, RB4) of a brake circuit (BK1, BK2) for the ABS function is carried out in a multiplexed operation by means of the pressure supply arrangement (DV1, DV2) assigned to the brake circuit (BK1, BK2), and in particular the volume of hydraulic fluid is regulated by means of the piston of the pressure supply arrangement for pressure setting.

19. Braking system according to any one of the preceding claims, characterized in that for selectively closing at least one hydraulic main line (4, 5) a switching valve (PD1) is provided, in particular a switching valve (PD1) is provided in the hydraulic main line (4) between a pressure supply (DV1) and a switching valve (BP 1).

20. A braking system according to any one of the foregoing claims, characterised in that the pressure reduction (P) is carried out in the wheel brake (RB1-4) continuously or simultaneously_Reduce)。

21. A braking system according to any one of the foregoing claims, characterised in that the pressure reduction (P) in the wheel brakes (RB1, RB2) of the brake circuit (BK1)_Reduce) Is carried out by a stroke movement of a piston of an associated pressure supply device (DV1) of the brake circuit, and the pressure in the wheel brake (RB3, RB4) of the other brake circuit (BK2) is reduced (P)_Reduce) By dissipating into the reservoir (VB) via the central discharge valve (ZAV) and the connecting switch valve (BP 2).

22. A braking system according to any one of the foregoing claims, characterised in that a redundant second discharge valve (ZAVr) is arranged and acts in the hydraulic line from the central discharge valve (ZAV) to the reservoir (VB).

23. A brake system according to any one of the foregoing claims, characterised in that each brake circuit (BK1, BK2) is provided with at least one pressure supply device (DV1, DV 2).

24. A braking system according to any one of the preceding claims, characterized in that at least one pressure supply device (DV1) has a piston-cylinder unit (1), the piston (Ko) of which piston-cylinder unit (1) is driven by an electric drive via a transmission device (SP), and the piston (Ko) of which piston-cylinder unit (1) is a single-reciprocating piston or a double-reciprocating piston, the transmission device (SP) being in particular a spindle drive.

25. A braking system according to any one of the foregoing claims, characterised in that the switch valve (SC) has a connection for the wheel brake downstream of its valve seat.

26. A braking system according to any one of the foregoing claims, characterised in that the drive motor of the pressure supply device (DV2) is a brush motor and the delivery volume for controlling the pressure increase is determined as a function of the rotational speed and the time and/or the angle of rotation.

27. A brake system according to any one of the preceding claims, characterized in that a piston (Ko) of the master brake cylinder (HZ) can be adjusted by means of an actuating device (P) for the increase of the pressure in a pressure chamber (A1) of the master brake cylinder (HZ), wherein in particular the piston-cylinder unit (HZ) optionally has a force-travel measuring element (KWS), the actuating device (P) in particular being in the form of a brake pedal.

28. A braking system according to claim 26, characterized in that the pressure chamber (a1) is connected via a hydraulic line (3) to a hydraulic main line (4) of one braking circuit (BK1), wherein two valves (FV, TV) connected in series are used for the selective closing and opening of the hydraulic line (3).

29. Braking system according to any of the preceding claims, characterized in that at least one pedal stroke sensor (PS), preferably two pedal stroke sensors (PS), is provided for detecting the position of the actuating device (P).

30. Braking system according to any one of the preceding claims, characterized in that the reservoir (VB) has a redundant level transducer, i.e. a second level transducer, in particular with redundant sensor elements.

31. A braking system according to any one of the foregoing claims, characterised in that the electronic open-and closed-loop control unit (ECU), the at least one pressure supply device (DV1, DV2) and the switching valve are arranged in one module, housing and/or structural unit.

32. A braking system according to any one of the preceding claims, characterized in that at least one electronic open-loop and closed-loop control unit (ECU) has two mutually separate on-board electrical system connections.

33. A braking system according to any one of the foregoing claims, characterised in that the piston-cylinder unit (HZ) has redundant seals (D1, D2, D3) so that a failure of at least one seal (D1, D2, D3) can be determined by means of a diagnostic method, wherein a stroke simulator (WS) is optionally provided.

34. A braking system according to any one of the foregoing claims, characterised in that a non-return valve or valve (MV) which opens on de-energisation is arranged in the hydraulic line leading to the vent of the piston-cylinder unit (HZ).

35. Braking system according to any one of the preceding claims, characterized in that a switching valve (PD1) is provided for selectively closing at least one hydraulic main line (4, 5) and that the at least one hydraulic main line (4, 5) can be connected to the reservoir (VB) via a central drain valve (ZAV), in particular for pressure reduction in at least one component (RB1, RB2, RB3, RB4) and/or two brake circuits (BK1, BK2) during ABS operation, wherein the pressure generation for the ABS function is performed by means of a single pressure generating device (DV1, DV2) for the two brake circuits (BK1, BK2) and the pressure generation for the two brake circuits (BK1, BK2) is performed by means of a single pressure generating device (DV1, DV2) for the two brake circuits (BK1, BK2) or in each case one pressure generating device (DV1) for each brake circuit (BK1, BK2), DV2) performs pressure generation for the ABS function.

36. A brake system according to any one of the preceding claims, characterized in that at least one pressure sensor or pressure transducer (DG, DG1, DG2) is provided for each brake circuit (BK1, BK2) or for both brake circuits (BK1, BK2) jointly, particularly preferably one pressure transducer (DG) is provided for determining the pressure in the brake circuit (BK2), the pressure generation in the brake circuit (BK2) being carried out by means of a pump (DV2) with continuous delivery action.

37. A braking system according to any one of the foregoing claims, characterised in that in normal operation, in particular also for ABS function, the slave pressure level (P) in the wheel brake₀) To locking pressure (P)₁) Pressure rise (P) of_{Is raised}) Is carried out by means of a pressure supply device (DV1) and a maximum pressure (P) is reached₂) Additional pressure rise (P)_{Is raised}) By means of a further pressure supply device (DV 2).

38. The braking system of claim 27, wherein for slave pressure level (f: (m)), (P₂) To a pressure level (P)₁) Pressure drop (P) of_Reduce) Can be carried out using pressure supply devices (DV1, DV2) or via a discharge valve (ZAV), and one, first pressure supply device (DV1) is used for the pressure level (P)₁) To pressure level (P)₀) The additional pressure of (a) is reduced.

39. A braking system according to any one of the foregoing claims, characterised in that in the event of failure of one pressure supply device (DV1, DV2), the still active pressure supply device acts in order to carry out a pressure increase in the wheel brakes (RB1-4) of both brake circuits (BK1, BK2) and a pressure decrease (P) in one or both brake circuits via the central exhaust valve (ZAV) and/or via at least one exhaust valve (AV1, AV2)_Reduce) The discharge valve (AV1, AV2) is arranged in particular between the Switching Valve (SV) and a connecting switching valve (BP1, BP2) or between a wheel brake (RB1-4) and an associated Switching Valve (SV).

40. A braking system according to any one of claims 36 to 38, characterized in that in the event of failure of the second pressure-supply device (DV2), a pressure build-up is carried out in both brake circuits (BK1, BK2) by means of the first pressure-supply device (DV1) only up to a locking pressure (P)₁)。

41. A braking system according to any one of the foregoing claims, characterised in that two non-return valves (RV1, RV2) are connected in series in a braking circuit (BK2), in which braking circuit (BK2) a pump (DV2) with continuous delivery is arranged, wherein the hydraulic lines connecting the non-return valves (RV1, RV2) to each other are connected to a reservoir (VB) via a hydraulic line in which a throttle valve (Dr) is arranged.

42. A braking system according to any one of the foregoing claims, characterised in that a pressure supply device (DV1) with an electrically driven piston (Ko) and four seals (D4, D5, D6, D7) is provided, between which channels are arranged, each end of which channels being located inside the cylinder, wherein one, the first channel is connected to a reservoir (VB) via a non-Return Valve (RV), and the second and the third channel are connected to each other via a hydraulic line in which a throttle valve (Dr) is arranged, and the third channel is likewise connected to the reservoir (VB) via a hydraulic line.

43. Braking system according to any of the preceding claims, characterized in that in the ABS function the pressure increase (P) is performed by means of only one pressure supply device (DV1, DV2) or by means of two pressure supply devices (DV1, DV2)_{Is raised}) Wherein the pressure build-up is carried out simultaneously or alternately in the brake circuits (BK1, BK 2).

44. A brake system according to claim 43, characterized in that in the ABS function, the pressure build-up (P) is carried out simultaneously or alternately in one or both brake circuits (BK1, BK2) by means of the connecting switching valves (BP1, BP2) by means of only one pressure supply device (DV1)_{Is raised})。

45. Braking system according to any of the preceding claims, characterized in that in the ABS function a pressure reduction (P) is performed in one or both brake circuits (BK1, BK2) by_Reduce)，

By means of a pressure supply device (DV1), or

-by means of said central discharge valve (ZAV), or

-via at least one discharge valve (AV1, AV2), the discharge valve (AV1, AV2) being arranged in particular between the on-off valve (SV) and a connecting on-off valve (BP1, BP2) or between a wheel brake (RB1-4), in particular a front wheel brake, and an associated on-off valve (SV).

46. A braking system according to any one of the foregoing claims, characterised in that the piston-cylinder unit (HZ) has a dedicated reservoir (VB).

47. A braking system according to claim 42, characterized in that the storage volume of the reservoir (VB) can be diagnosed and changed by means of said one pressure supply device (DV 1).

48. A braking system according to any one of the foregoing claims, characterised in that an electric pedal is provided and that the control signal of the electric pedal is an input signal for the electronic open-loop and closed-loop control unit (ECU) of a hydraulic system, which in particular has a partially or fully redundant configuration with two supply connections.

49. A brake system according to any one of the foregoing claims, characterised in that at least one pressure supply device (DV1, DV2) is used for closed-loop pressure control or pressure build-up in the parking brake (EPB).

50. Braking system according to one of the preceding claims, characterized in that at least one electrically actuated parking brake (EPB) contributes in an auxiliary manner to a pressure increase, in particular to a closed-loop pressure control of the ABS function.

51. Braking system according to any one of the preceding claims, characterized in that a further on-off valve (FVr) is connected in parallel with respect to the valve (FV), wherein the output and the input of the valve (FV, FVr) are connected to the line (3) in an interchangeable manner.

Technical Field

The invention relates to a hydraulic system having at least two brake circuits that can be connected to each other in a fail-safe manner.

Background

The requirements for semi-automatic (SAD) and Fully Automatic (FAD) driving, and in particular the safety requirements for semi-automatic (SAD) and Fully Automatic (FAD) driving, have a major impact on the system configuration. These require redundant or partially redundant systems and components.

The focus here is on the pressure supply, by which the braking force or pressure rise must be ensured, even without the foot of the driver. The electronic controller must also be configured accordingly for this function. For a level 3, in particular a level 4, the ABS function must likewise be ensured, even in the event of a malfunction.

With a redundant pressure supply, it is also possible to implement a system concept without a tandem master cylinder HZ using only a so-called electric pedal or, for 5-stage, only a brake switch. Here, the following patent applications are noteworthy: DE 102017222450 discloses a hydraulic system with only one master cylinder, a redundant pressure supply, an isolation valve for the master cylinder and a travel simulator. A bypass valve between the two brake circuits allows the supply of both brake circuits in the event of a pressure supply failure of the second pressure supply. The valve opening on power failure is highly safety related, since failure of the valve and failure of e.g. the brake circuit may lead to a complete brake failure. Furthermore, the cost of the valve is very high.

DE 102017222435 and DE 102016225537 propose a similar concept but with an electric pedal, reduced pressure supply and a bypass valve. During the pressure drop, all systems use a so-called outlet valve for the ABS function. If dust particles enter the valve seat of the valve when the valve is open, this can lead to failure of the brake circuit during the next braking operation.

DE 102017207954 proposes a system concept with redundant pressure supply without an outlet valve for closed-loop ABS pressure control. The multiplexing method described in DE 102005055751 is used here, in which the pressure control for the ABS is carried out by pressure supply with the aid of volume measurement and pressure information. Here, the on-off valve for pressure control is also used redundantly. If the check valve or piston seal of the reservoir fails and the on-off valve leaks due to dust particles, this also results in a complete brake failure and thus a safety risk.

The above examples illustrate the problem of latent faults, which becomes critical in the case of double faults, if these cannot be detected by diagnostics before the braking operation.

Disclosure of Invention

Objects of the invention

It is an object of the present invention to provide a more fail-safe hydraulic system having two brake circuits.

This object is achieved

According to the invention, this object is achieved by a brake system having the features of claim 1. Further advantageous configurations of the hydraulic system according to claim 1 result from the features of the dependent claims.

THE ADVANTAGES OF THE PRESENT INVENTION

By providing two connection switching valves connected in series for connecting two brake circuits of the brake system according to the invention, a high level of fail-safety is advantageously achieved.

In a first alternative, in order to increase the failsafe, the invention provides that the two connection switching valves which are opened when energized and are designed in particular as 2/2 directional valves have their valve connections arranged in the brake system such that: in the de-energized state, the two connection switching valves open in a manner assisted by the pressure that may be present in the respective hydraulic main lines or brake circuits. This can be achieved in particular by: the valve connection of the connection switching valve, which is assigned to the valve seat, is hydraulically connected to the hydraulic main line, so that the pressure prevailing in the hydraulic main line pushes the valve control element away from the valve seat. As an alternative or in combination to the first alternative, the inner section of the connecting line which connects the two connections of the connecting switching valve directly to one another may be connected to the pressure chamber of the master brake cylinder via a further hydraulic line, wherein at least one valve is arranged in the further hydraulic line for selectively closing the further hydraulic line. In this way, it may be advantageous that, in the event of a fault, the pressure can be increased in one or both brake circuits by means of a master brake cylinder, which can be actuated, for example, by means of a brake pedal.

The hydraulic system according to the invention may thus have a pressure supply for each brake circuit. However, it is also possible to provide only a single pressure supply for both brake circuits, without the function of the hydraulic system thus becoming significantly more prone to faults. Redundancy is created by the series connection of two connecting valves. Furthermore, the valve can be checked for tightness and switching function. Thus achieving an extremely high level of fail-safe.

The master brake cylinder with the travel simulator should also be fail-safe, which can be achieved, for example, by means of redundant seals, and failure of the master brake cylinder can be monitored. This advantageously makes it possible to dispense with a complicated, large and expensive tandem master brake cylinder and to use only one master brake cylinder with one pressure chamber.

If the hydraulic system according to the invention is used as a brake system, the pedal movement can again be measured redundantly by means of two redundant pedal travel sensors or at least a main sensor. The pedal travel sensor may preferably be coupled to a force travel element, such as for example the force travel element known from WO/2012/059175a1, for fault detection of the travel simulator, for example.

The connection valves from the master brake cylinder to the brake circuit and the pressure supply are also safety-relevant, since a failure allows a connection to the pressure supply, which influences the pedal and changes the pedal characteristics. This connection is also secured by means of the valve assembly described above for connecting the two brake circuits, since it leads to a redundant series connection of two valves between each pressure supply and the master brake cylinder, so that: in the event of failure of one of the valves, no undesired reaction is still given to the pedal.

The pressure increase and pressure reduction in the wheel brake can advantageously be achieved by means of a multiplexing Method (MUX), i.e. setting or setting by closed-loop control, assigned to the wheel brake or to a switching valve connected immediately upstream of the wheel brake, in which case the pressure supply sets the pressure in the wheel brake with the switching valve open. In this case, additional outlet valves for the wheel brakes, such as those used in classical ABS systems, can advantageously be dispensed with. However, it is also possible to provide one outlet valve or outlet valve for each brake circuit or only one outlet valve for both brake circuits for pressure reduction. If two redundant pressure supplies are provided, for example by means of a plunger and a piston pump, the above-described multiplexing method can be implemented using two pressure supplies simultaneously or separately in one or both brake circuits.

In the known MUX method, pressure is generated by means of a central electric piston unit, whereby, and by this pressure interacting with one valve of each wheel, a pressure regulation P for the ABS is generated_{Is raised}And P_Reduce. In this case, four wheel cylinders, i.e., channels, must be operatedDo this. By means of the pressure-volume characteristic curve, the volume change produced by the piston can produce a corresponding wheel pressure/pressure change. In this case, P cannot be generated simultaneously in the system_{Is raised}And P_Reduce. However, P_ReduceShould occur with only a short delay, wherein the switching time is dependent on the pressure change P_{Is raised}And P_ReduceWith adverse effects.

If two pressure supply devices are provided, each pressure supply device only needs to perform a closed-loop pressure control of components, in particular the wheel brakes, which are arranged in the brake circuit assigned to the pressure supply device. That is, the multiplexing method need only be configured for two channels or two wheel brakes. Only in the event of a malfunction, the MUX method must be implemented by means of the connection of the two brake circuits by means of one pressure supply for all wheel brakes.

If at least one outlet valve is also provided for the pressure reduction, the hydraulic system according to the invention can also be operated with only a single pressure supply, since this makes it possible to simultaneously carry out a pressure increase in one brake circuit by means of the pressure supply and a pressure reduction in the other brake circuit by dissipation to the reservoir via the outlet valve.

If one pressure supply device is an electrically operated plunger piston and the other pressure supply device is, for example, a simple piston or gear pump, the pressure supply device can be reduced in size to save costs by means of a motor which is designed only for a plunger pump with a high μ, for example 120 bar, and a simple piston or gear pump which is designed for, for example, 200 bar. Furthermore, in another embodiment, the plunger pump may optionally be combined with a brushless motor, and the piston pump with a brushed motor as in the case of ABS/ESP.

If two pressure supply devices are provided, they can also be connected in parallel or together by means of two connecting valves for rapid pressure increase. This advantageously allows the size of the driver to be reduced. Furthermore, in this way, the pressure difference due to the back pressure of the connecting valve can be advantageously reduced. The plunger piston can also advantageously have redundant seals, the tightness of which can also be checked. The pressure supply device may likewise be provided with a second monitorable non-return valve. In order to connect the two brake circuits, instead of the two pressure supplies, a plunger pump having a redundant electric motor with 2 × 3 phase windings can also be used in the valve assembly according to the invention. The motor may also be combined with a driver and a double-acting piston.

The electronic open-loop and closed-loop control devices may have a fully or partially redundant configuration, and may also have corresponding on-board electrical system connections for various functions. In particular, the control of the valves can have a redundant configuration of the isolating switches for the individual valve drives, in order to enable fail-safe control in each case of a fault, for example in the event of a short circuit of the drive.

The level sensor in the reservoir should continuously measure the liquid level in order to identify a leak at an early point in time of the liquid level change. The sensor can also be of redundant design, which is easy to implement in the case of an electronic open-loop and closed-loop control device which rests against the reservoir and is arranged in a sensor element on the circuit board.

Fault analysis shows that double faults, in some cases even triple faults, are advantageously dealt with in the case of not complete failure of the hydraulic system or the brake. In this case, essentially a single fault can be diagnosed in order to identify potential faults.

In the case of a redundantly configured pressure supply device, the probability of failure of the entire pressure supply is extremely low and is in fact relevant only in the case of a failure of the on-board electrical system. This means that a redundant series master brake cylinder (THZ) can be dispensed with. However, with the concept according to the invention, a master brake cylinder with a redundant seal that can be checked and with only one pressure chamber is proposed, whereby the fail-safety is increased and is therefore equivalent to a tandem master brake cylinder.

With such fail-safe valve assemblies, the number of valves can be reduced by about 40% compared to known valve assemblies for integrated one-tank systems, which are expensive in valves and are also not more fail-safe. Furthermore, only 50% of the valve variants are required compared to the one-tank system described above.

In the case of one of the two pressure supply devices, the use of the motor-driven pumps of the ABS and the EPS is convenient, with advantages in both installation space and cost.

As is known, the parking brake EPB can be assisted in the braking of the brake to reduce the size of the electric motor of the parking brake. Using redundant pressure supply means, it is even more efficient and safer.

With the hydraulic system according to the invention, the brake action, the ABS function and the pedal behavior are advantageously ensured by the redundantly arranged components or assemblies and the valve circuit, and the fail-safe is adequately ensured.

Various possible embodiments of the invention will be discussed in more detail below with reference to the accompanying drawings.

Drawings

In the drawings:

fig. 1 shows a first possible embodiment of a hydraulic system according to the invention with fail-safe valve assemblies for connecting two brake circuits, with a master cylinder with an actuating device and with two pressure supply devices with electronic open-loop and closed-loop control devices as a so-called integrated one-tank system;

fig. 1a shows a possible valve circuit variant for connecting two brake circuits;

FIG. 1b shows an alternative embodiment with a different connection of the second pressure supply;

FIG. 1c shows the function of a brake system with two pressure supply devices;

fig. 1d shows the function in the event of failure of the switching valve of a brake circuit and/or a wheel brake;

fig. 1e shows the function of the hydraulic system in case of failure of both pressure supplies;

FIG. 2 shows a system with a master cylinder as a separate module;

FIG. 3 shows a hydraulic system with only one pressure supply, however with redundant motor controls;

fig. 3a shows the hydraulic system according to fig. 3, but with a pressure supply with a double-acting piston;

FIG. 4 shows the valve assembly of the E/X booster in combination with the ESP;

fig. 5 shows a brake system with an electric pedal.

Detailed Description

Fig. 1 shows the basic elements of a closed-loop controllable brake system, which comprises a master brake cylinder HZ with a travel simulator WS and a reservoir VB, and two pressure supply devices DV1 and DV2, wherein the pressure supply device DV1 has an electric piston control and the second pressure supply device DV2 has a simple circuit piston or gear pump. The two pressure supply devices interact with a valve circuit on the wheel brake cylinder RZ, which transmits the closed-loop wheel pressure to the brake, for example in the case of an ABS. This corresponds to the prior art. However, the hydraulic system according to the invention is intended to have a high level of fail-safety for semi-autonomous driving (SAD) or Fully Autonomous Driving (FAD).

For this reason, all components related to the malfunction, such as valves, sensors, seals, motors and brake circuits, should be considered. Therefore, the following components or hydraulic connections should advantageously be designed with fail-safety:

(1) connection from a pressure supply device DV1 provided for the first brake circuit to the second brake circuit BK 2;

(2) a connection from a pressure supply device DV2 provided for the first brake circuit to the first brake circuit BK 1;

(3) the connection of the pressure chambers of the master brake cylinder HZ via the valves FV via the valves BP1 and BP2 to the brake circuits BK1, BK 2;

(4) the connection of valve PD1 and valve BD1 to wheel brake cylinders RZ via the respective switching valves SV assigned to the wheel brakes;

(5) the connection of valve BD2 to wheel brake cylinder RZ via the respective switching valve SV assigned to the wheel brake;

(6) connections from brake circuits BK1, BK2 to reservoir VB;

(7) the connections between the brake circuits BK1, BK2 and the wheel brake cylinders RZ.

The failure caused by these hydraulic connections and possible failure of individual components will be described below.

The pressure supply device DV1 acts from the brake circuit BK1 via the hydraulic line paths 1, 2 and 5 into the brake circuit BK2 and via the switching valve SV into the wheel brakes RB. In the prior art, only a single bypass valve is used for this purpose. Here, if another valve also has a potential failure, the valve failure may result in a complete brake failure. Therefore, the present invention provides two redundancy valves BP1 and BP2 so as to allow connection from the first pressure-supply device DV1 to the brake circuit BK 2. Potential faults of the valves BP1 and BP2 are identified by the pressure transducer by means of a short circuit of the valves in the event of a pressure change. At this stage, the pressure must be kept constant. In the event of failure of the first pressure supply DV1, for example in the event of failure of a piston seal, a reaction to the brake circuit BK2 via the three redundancy valves BP1, BP2 and PD1 is prevented. The valves are preferably valves which open when de-energized, so that master brake cylinder HZ can act on brake circuits BK1 and BK2 in the event of a failure of pressure supply devices DV1, DV 2. If the pressure is reduced by opening valve ZAV or FV, the two connection switch valves automatically open due to the applied pressure differential without requiring special electrical actuation thereof.

Accordingly, the pressure supply device DV2 in the second brake circuit BK2 acts on the hydraulic line 4 via the hydraulic lines 2 and 5 and via the valves BP2 and BP1, and acts on the wheel cylinder RZ from the hydraulic line 4 via the switching valve SV. In the event of a failure of the brake circuit BK in the wheel brakes RB, the valves SV, BP1, and BP2 are closed early through diagnosis, and a failure of the pressure supply is prevented. Here, all valves, for example SV, BP1, BP2, are considered safety critical for potential failure, since the hydraulic medium flowing through the valve contains dust particles that can prevent the valve from closing and the valve therefore leaks. In the present case, for example in the event of failure of a switching valve SV, a brake circuit may fail in good time. However, the other brake circuit is protected by the interaction of the two valves BP1 and BP 2. In this case, a triple failure is necessary, i.e. both valves BP1 and BP2 must additionally fail before a complete failure can occur. The at least one brake circuit is thus reliably protected against double failure and against complete brake failure. Safety with respect to double failures is an important safety feature for SAD and FAD if a potential failure may occur. This also includes maintaining the pressure supply or brake booster in the event of a brake circuit failure.

The pressure supply device DV2 can assist the further pressure supply device DV1 in the event of rapid pressure increases or pressure increases of 120 bar or more, and/or can carry out the pressure supply in the event of pressure drop by continuous conveying and/or for ABS functions, and/or can carry out the function of the further pressure supply DV1 jointly in the event of a failure of the further pressure supply DV 1.

It is also possible for the pressure supply device DV1 to perform a pressure increase for a pressure range below or equal to 120 bar and for the ABS function. In the event of failure of the pressure supply device DV2, a maximum pressure of 120 bar can only be achieved for both brake circuits if the pressure supply device DV2 is designed only for a maximum pressure of 120 bar.

With the connection valves BP1 and/or BP2 closed, the pressures in the brake circuits BK1 and BK2 of the two pressure supply devices DV1 and DV2 can be set independently of one another or by closed-loop control with the two pressure supply devices DV1 and DV 2.

According to WO2012/059175a1, the pedal movement is measured by means of a redundant pedal travel sensor (PS), which simultaneously acts on a force travel sensor (KWS) measuring element. The pressure supply device DV1 is controlled by a signal from a pedal stroke sensor, wherein the piston control causes a volume in the hydraulic main line 1 in the brake circuit BK1 to flow into the brake circuit BK2 via the redundant valves BP1 and BP 2. The pressure supply device DV1 can be designed to act only up to a locking pressure, for example 120 bar. The higher pressure is then provided by pressure supply device DV2, which pressure supply device DV2 carries the volume into brake circuit BK2 and via redundant valves BP1 and BP2 into brake circuit BK 1. Here, the pressure supply device DV2 may be a pump with continuous delivery action. If the brake system is poorly ventilated or if steam bubbles occur, which leads to a greater volume requirement, this is detected by the known pressure-volume characteristic (p-v characteristic), with the result that the pressure supply device DV2 is already active, even at lower pressures. With regard to pedal actuation, it must additionally be mentioned that this moves a piston Ko, which acts on a known stroke simulator WS by means of a pressure which is proportional to the pedal force and thus determines the characteristics of the pedal. The stroke simulator WS can be normally closed by a valve, in particular at the level of the fall back in the case of a failed pressure supply. In the case of redundant pressure supply devices, this is no longer relevant due to the very low probability of failure.

Master brake cylinder HZ may be connected via a line 3 to brake circuit BK1 or BK2, wherein a valve FV is arranged in line 3 for closing line 3. This connection is only effective at the fallback level. The two valves BP1 and BP2 create further redundancy if the line is connected to the connecting line of the two on-off valves BP1 and BP 2. A conventional connection directly from the valve FV to one of the two brake circuits BK1 and BK2 would result in the brake circuit and thus the pressure supply acting on the master cylinder (HZ) piston in the event of a leak from the valve FV, which normally results in the pressure supply being closed.

Various pressures or pressure levels from the master brake cylinder and from brake circuits BK1 and BK2 act on valve FV. In the worst case, this may result in an unfavorable pressure difference at the closed valve FV and the valve FV cannot open, such that the pressure drop P occurs in the event of a failure of the on-board electrical system or of the open-loop and closed-loop control unit ECU, for example_ReduceIt cannot be done. To prevent this, another on-off valve FVr is connected in parallel with valve FV, wherein the outputs and inputs of valves FV and FVr are connected in a reciprocal manner to line 3 such that: in the presence of any pressure differenceDue to the pressure difference, it is ensured that one of the two valves FV, FVr opens automatically, that is, even without energization. Furthermore, this advantageously reduces the back pressure on the valve.

In the event of a failure of the brake circuit in the wheel cylinder, the respective inlet valve EV or switching valve SV is normally closed in order to eliminate the failed wheel circuit. A leaking inlet valve EV/switching valve SV (potential failure) causes the brake circuit or the entire pressure supply to fail. Here, BP2 and BP1 also provide additional safety so that the pressure supply does not fail. A failure of the brake circuit BK1 due to the inoperative switching valve SV means that the pressure supply DV1 is failed, whereby a pressure supply to the still active wheel brakes is carried out by means of the further pressure supply device DV 2.

Additional failure in the second brake circuit results from failure of check valve RV 1. In this case, a pressure supply DV2 can be prevented from failing by means of a redundant non-return valve RV 2. The throttle Dr with a small pressure flow downstream of the check valve RV2 allows for diagnosis, for example, by pressure drop.

Closed loop ABS control or pressure reduction by the second pressure supply DV2 requires a central outlet valve ZAV. In this case, the volume flow additionally passes through the valves BP1 or BP2, so that a leaking central outlet valve ZAV is not critical for normal operation, in the event of a failure of the central outlet valve ZAV, the pressure control being performed by means of the pressure supply devices DV1 and DV 2. Furthermore, malfunctions, even potential malfunctions, are identified by the central outlet valve ZAV as a function of the pressure change or increased volume delivery of the pressure supply DV 1. During normal braking up to approximately 120 bar, the pressure supply DV acts in the two brake circuits BK via the open valves BP1 and BP 2. For extreme safety requirements, a redundant bleed valve ZAVr may also be installed in the line to the reservoir VB.

Failures in master brake cylinder HZ and stroke simulator WS are typically caused by seals. In the case of master brake cylinder HZ, an additional seal D3 and a throttle valve may be used in the return line to reservoir VB, in order to be able to diagnose a failure of the seal at an early point in time. A leakage can thus be detected by means of the pedal travel sensor from a small additional pedal movement. Low loads have to be considered in the case of SAD and FAD.

In many systems, for the diagnosis of seals, a solenoid valve that is open when de-energized is included in the return line, which solenoid valve is closed for diagnosis. In this case, pressure is conducted from pressure supply DV1 via valves PD1, BP1 and EV into master brake cylinder HZ. The diagnosis is performed by a change in pressure at a constant piston position or a change in piston position at a constant pressure. Alternatively, a combination of a throttle valve and a check valve may be used to save costs. The throttle valve is dimensioned such that the leakage flow through the seal results in only a slight displacement of the pedal within a normal braking time of about 10 seconds.

The same solution is also used for stroke simulator (WS) pistons with redundant seals diagnosed by pedal movement as described above with respect to seal D3. Furthermore, even if these seals fail, control of the brake boost is still possible despite variations in pedal characteristics. Here, the failure rate of two seal failures is extremely low, almost less than 10^-10In the range of one year. The pressure supply DV1 may also be equipped with a redundant seal, as described above in the case of the master brake cylinder HZ, with a seal D6 with a throttle between seal D6 and seal D5. If the suction valve is directly connected to the connection on the valve PD1, suction starts immediately with the return stroke of the piston, with the advantage of providing high suction power even at low temperatures. In extreme cases, failure or leakage of the switching valve SV can lead to failure of the pressure supply DV. The compromise is to connect the switching valve SV at about 60% of travel. This means that the stroke of 40% can be unaffected by the leaking on-off valve SV while suction action can be performed in the normal temperature range. Due to the above-mentioned small restrictions, the volume delivery of the piston is ensured by redundancy. Furthermore, the motor can be controlled by means of redundant 2 × 3 phase windings, so that the pressure supply DV is deactivated only by the blocked ball screw drive KGT.

ABS operating MUX and pressure supply by means of multiplexingThe ABS function to be performed by the device DV1 is performed as described in WO 2006/111393 a 1. The central drain valve ZAV results in an expanded MUX function. If the pressure in the brake circuit BK1 rises P_{Is raised}Meanwhile, a pressure decrease P is required in the other brake circuit BK2_ReduceThis is performed by means of the central discharge valve ZAV and the simultaneously closed valve BP 1. In this way, the multiplex system MUX is loaded only by the two wheel brakes RB1, RB2 in the brake circuit BK1, i.e. the pressure rise P_{Is raised}And pressure decrease P_ReduceCannot occur simultaneously in wheel brakes RB1 and RB2 of brake circuit BK 1. Alternatively, the outlet valves AV1, AV2 in the respective brake circuit can also be used for the pressure reduction P_ReduceIn order to reduce the load of the MUX. Here, the outlet valves AV1, AV2 may be arranged or connected between the switching valve SV and the connecting switching valves BP1, BP2, or between the wheel brakes and the associated switching valve SV such that a direct pressure reduction P occurs by dissipation via the outlet valves to the reservoir VB_Reduce. This corresponds to a pressure drop P in the front wheel_ReduceIs particularly advantageous. In this alternative, central drain valve ZAV is not required.

In this case, in particular at P_ReduceDuring which there is no P_{Is raised}In the case of (2), the ABS function performed by means of the second pressure supply device DV2 is performed in a somewhat limited manner. Nevertheless, a completely independent closed loop ABS control is still possible. It must be considered that the pressure supply device DV2 is rarely used at pressures greater than 120 bar and in the event of failure of the first pressure supply device DV 1.

Closed-loop pressure control is typical for the above-described MUX operation, likewise taking into account the pressure-volume characteristic (p-v characteristic) in the case of ABS, either by volume measurement or by piston movement of the pressure supply DV 1. In the case of simple eccentric piston pumps, this is not achieved by piston movement, but by delivery time, i.e. volume and additional rotational speed measurements, and pressure measurements (if necessary). For pressure increase P_{Is raised}Measuring the volume is also possible. Here, at a pressure rise P_{Is raised}In the case of a continuous and non-simultaneous pressure increase P in the respective wheel brake_{Is raised}Is advantageous. Here, valve size and back pressure on the valves must be taken into account, especially in the case of rapid pressure rise in the wheel circuit of the valves BP1 and BP 2. The back pressure of the above-described valves acts as a pressure differential between the brake circuits BK1 and BK 2. This situation can be significantly reduced if both pressure supply devices DV1 and DV2 are activated in this operating state. Here, a single-circuit gear pump instead of a piston pump is also advantageous. The pressure increase P can also be carried out here by means of a gear pump_{Is raised}And pressure decrease P_Reduce. For this purpose, instead of the non-return valve RV, a valve MV (not shown) is required in the return line to the reservoir VB. A complete MUX operation is therefore also possible via the second pressure supply DV 2.

The open-loop and closed-loop control unit ECU is an integral part of the whole system and package. Fail safe functionality requires redundant or partially redundant ECUs. Such partially redundant ECUs may be used in addition to redundant ECUs for specific functions. In any case, the valve is or should be redundantly driven by means of a separate valve drive and a disconnector, which closes the failed valve drive.

Redundant on-board electrical system connections are also necessary for redundancy of the open-loop and closed-loop control unit ECU. The connection made through 48V can also be used for the connection of the motor. The advantage of 48V is higher power. In the event of a failure of the motor of the pressure supply DV1 at 48V, emergency operation by 12V is achieved with about 50% of the power, while reducing power and saving costs. For this purpose, a motor configuration for 24V is necessary, for example.

Pressure transducer DG is preferably used in brake circuit BK2, and may also be used in brake circuit BK 1. In the event of a pressure transducer failure, closed loop pressure control may be performed by using the p-v characteristic curve for piston position control and for motor inrush current measurement.

Alternatively, a hydraulic connection from the pressure supply of the brake circuit BK2 to the internal connecting lines VLa of the valves BP1 and BP2 may be effected, as shown in fig. 1b in combination withX represents. In this alternative, the pressure supply device DV2 no longer acts directly into the brake circuit BK 2. This has the advantage in case of failure of the valve BP2, SV and pressure supply DV 1. In this case, a failure of the pressure supply devices DV1 and DV2 can be avoided by means of the pressure supply device DV2 acting in the brake circuit BK1 with the valves BP2 and PD1 closed. However, for less than 5-10^-6A/year wheel circuit failure, i.e., 5 failures in one million vehicles per year, must be considered to have less than about 5-10^-18Triple failure with minimum probability of failure per year. This is contrary to many drawbacks; for example, in the event of a failure (e.g., a leak) of valve FV, the pressure supply in brake circuit BK2 may also fail.

In the pressure lines of the pressure supply devices DV1, DV2, pressure relief valves can be arrangedTo protect the drive, in particular the shaft and/or the ball screw drive, which pressure relief valve opens, for example, at about 120 bar.

Fig. 1a shows an extension of the valve assembly with an additional isolation valve TV as a redundancy with respect to the valve FV. In this case, a pressure supply (DV) connection can be made between the valve BP1 and the TV, with the result that the Switching Valve (SV) fails (rarely, less than 10 ≦ for)^-9Year) brake circuit BK1 does not cause pressure supply device DV1 to fail. This is in contrast to the additional expense and safety protection of brake circuit BK1 being connected to brake circuit BK2 via only one BP valve.

The hydraulic connection of the valve from the outside and the inside to the valve seat is also very important. In this case, a fault situation must be taken into account, in which the electrical connection to the valve coil or to the valve coil itself fails despite the redundancy. If the pressure drops in this case, again due to component failure, the valve must open due to the pressure differential. The pressure cannot be kept limited. For example, when the driver releases the brake pedal, the FV valve may reduce pressure and release volume into the low-pressure master brake cylinder HZ. Without such measures, after a braking operation, the vehicle will stop or continue to run at a previously set pressure, which will result in the brakes overheating and completely failing. Although redundant control of the valves is described, this extremely rare case does not necessarily occur and can be avoided. This is another security feature of the proposed solution. Thus, as shown in the figure, all valves are connected to the hydraulic line, so that during a pressure reduction to master brake cylinder HZ via valves ZAV and DV1 or via valve FV, the valves are always open due to the existing pressure difference, without the need for electrical activation.

Alternatively, closed-loop ABS control can also be performed by means of a modified electric parking brake EPB, by means of the pressure supply device DV1 or DV2 and the two connecting switching valves BP1 and BP 2. Here, in order to create redundancy, it is also possible to use the motor of the electric parking brake EPB for closed-loop ABS control at a relatively low power. The hydraulic main lines 4, 5 are then connected to the electric parking brake EPB.

FIG. 1c shows the increase in pressure P_{Is raised}And a pressure reduction period P_ReduceThe function of the pressure supply devices DV1 and DV 2. The piston of pressure supply DV1 produces a volume which is transferred via valve PD1 into brake circuit BK1 and via valves BP1 and BP2 into brake circuit BK 2. The pressure is measured by means of a pressure transducer DG. For pressure reduction P_ReduceThe piston moves backwards with a corresponding volume return. In the event of failure of the higher pressure or pressure supply device DV1, pressure supply device DV2 is active and delivers volume directly into brake circuit BK2 and via valves BP1 and BP2 into brake circuit BK 2; valve PD1 is closed. Pressure drop P_ReduceThis can be performed by means of a pressure supply DV1, wherein a volume of more than 120 bar flows out via the vent. Alternatively, the pressure is reduced by P_ReduceMay be performed via central drain valve ZAV. Here, too, pressure measurement and closed-loop control are carried out by means of the pressure transducer DG. In the event of a failure of pressure transducer DG, the inrush current and stroke measurements of the piston may also be used as a substitute signal.

Another advantage is the possibility of assisting the parking brake EPB during parking. One or both pressure supply devices DV1 and DV2 may be used to generate a preload in the parking brake, so that the electric motor of the parking brake may be configured to be reduced in power and torque. This use is sufficiently fail-safe due to the redundant pressure supply.

Fig. 1d shows the effect of a fault/failure. In the event of failure of the brake circuit BK1 in the wheel cylinder or the supply line, the open-close valve SV is closed. In the event of a double failure of the wheel brakes and in the switching valve SV, the brake circuit BK1 fails and pressure is generated in the brake circuit BK1 by means of the pressure supply device DV 2. A similar situation applies to the case where the wheel brakes RB and/or the valves SV in the brake circuit BK2 fail. Then, the pressure supply device DV1 generates a pressure in the brake circuit BK 1. The safety function of the redundancy valves BP1 and BP2 is very important here.

Fig. 1e shows the effect in the case of failure of both pressure supply devices DV1 and DV2, for example in the case of failure of the on-board electrical system. Here, the pressure is generated by means of pedal actuation and a piston. The volume is transmitted via the valves FV, BP1 into the brake circuit BK1 and via the valves FV, BP2 into the brake circuit BK2 and the stroke simulator WS. It should be noted that fail-safe master brake cylinder HZ with redundant seals may potentially reduce the need for redundancy in the onboard electrical system to save costs. Here, partial redundancy in the ECU may be used for various functions, such as simplified closed loop ABS control.

Embodiments show that in the event of a leak, superior fail-safe is achieved by the rational use of redundancy with latent fault diagnosis. The optimized valve assembly results in less expense than is the case with conventional and fail-safe systems. Simultaneous double failures are extremely rare, i.e. at 10^-9In the range of one year. In the event of an extremely important double failure, for example in the case of a brake circuit failure in the wheel brakes or in the switching valve SV, a complete brake circuit failure can even be avoided, since a completely effective brake circuit is still available for the brake boosting.

Fig. 2 shows the possibility of the modular braking mentioned in the preceding paragraph with a separate master brake cylinder HZ associated with the master unit, which brings advantages with regard to installation and noise transmission to the bulkhead (bulkhead). The disadvantage is a separate reservoir, possibly with a level transducer and a small ECU for recording the sensor signal and transmitting the signal to the central ECU.

Another problem arises if, for the diagnosis of the master brake cylinder HZ, additional volume is taken from the pressure supply DV1 via a throttle into the reservoir VB 2. The solution is to perform the diagnosis at low pressures of less than 5 bar. In any case, where it is diagnostic that a pressure measurement is necessary, no pressure drop indicates that the reservoir VB is already full. Here, the cover of the reservoir VB has an integrated check valve RV. Furthermore, after diagnosis, a certain volume is drawn from the reservoir VB by the pressure supply DV. Therefore, the additional fluid level sensor NS may be omitted, and diagnosis of the master cylinder HZ is possible.

Fig. 3 and 3a show the use of a valve circuit in the case of only one pressure supply DV 1. A piston with redundant seals as described in fig. 1 is suitable for this purpose. Further, as is known, the motor control may be performed by 2 × 3 phases. This requirement may meet the lower requirements of level 3. The motor and drive must be designed for pressures above 120 bar. To avoid the effect of a double failure of brake circuit BK1 and switching valve SV, isolation valve TV can also be used in brake circuit BK 1. This solution is mainly suitable for smaller vehicles. The hydraulic lines 4, 5 of the two brake circuits BK1 and BK2 can be connected to pressure supply devices DV1 and DV2 and wheel brakes RB1-4 by means of different valve circuits, for example with multiplexed operation according to fig. 1 or with separate conventional closed-loop wheel control with inlet and outlet valves for each wheel brake.

Fig. 3a shows the use of a two-circuit dual-acting piston, the forward stroke of which is supplied via valve V1 to brake circuit BK1, and the return stroke of which is supplied via brake circuit BK 2. The two circuits of double-acting pistons can be fed into the second brake circuit BK via valves BP1 and BP 2. As known from WO2016/023994A1 and WO2016/023995A1 for P_ReduceThe volume of the double-acting piston must be controlled by a valveV3 and valve V4 vent into reservoir VB.

Fig. 4 shows two possible solutions 1 and 2 for the valve assembly of an E/X supercharger in combination with an ESP. Here, according to the modified valve circuit of fig. 1, an additional valve for the ESP may be omitted such that the valve assembly corresponds to that of the ABS having the inlet valve EV and the outlet valve AV and the storage chamber SpK, thereby achieving lower cost and lower weight associated with the ESP valve assembly. In option 1, the pressure supply device DV1 delivers volume via valves BP1 and BP2 into the brake circuits BK1 and BK 2. In the event of a failure, the volume is no longer sucked in from the reservoir with the fill level sensor NS via the E/X booster but directly via the non-return valve RV2, which is advantageous for the operating situation for various functions, since lower suction losses occur with respect to the sleeve with the additionally closed travel simulator, since the main brake cylinder delivers the replenished volume. In scheme 2, the valve USV remains, while the valve HSV can be omitted, since the suction is performed via the suction valve SV via the valves BP1 and BP 2. Here, the valve HSV closes.

All functions, such as brake circuit (BK) failure or Switching Valve (SV) (inlet valve (EV)) failure, correspond to the description in fig. 1, with the advantages presented. The position of pressure transducer DG, which in this case is located in brake circuit BK2, may vary. The connections from the valve FV to the valves BP1 and BP2 can also be connected directly to the valve BP1 without redundancy (see dashed lines).

The system not only has cost and weight advantages, but also increases the level of fail-safe, especially by level measurement in the reservoir when a leak occurs in the system. The sensor should also have a redundant design, which is easy to implement in the case of an ECU against a memory, wherein the sensor elements may be arranged on a circuit board.

Finally, such a valve assembly may be used in an E/X booster. The advantages are that: less expense on the valve, lower cost and lighter weight, with the advantage of increased fail-safety.

With such a fail-safe valve assembly, the number of valves can be reduced by about 40% compared to known valve arrangements of integrated one-tank systems, which have a higher cost on the valves and are not fail-safe.

The pressure supply devices DV1 and DV2 can be used not only for pressure supply for ABS and/or ESP functions, but also for recuperation and control of the torque vector.

Fig. 5 shows the pressure supply devices DV1 and DV2 with valve assemblies. In this case, an electric brake pedal, the so-called electric brake pedal, is combined in one unit with a stroke simulator (WS) pedal stroke sensor having a small sensor ECU and a force/stroke sensor KWS of a master brake cylinder HZ which does not have a hydraulic action. This is advantageous in situations where the installation volume in the engine compartment is small or where noise requirements are high. Instead of a master cylinder HZ (not shown in fig. 5) with a reservoir VB, a pedal actuation device with a travel simulator WS, a so-called electric pedal, can also be used. The signals of the pedal stroke sensor are processed in the sensor ECU and fed to the central ECU. For stage 5, the brake switch may also be used as a substitute for the electric pedal.

The unit has a two-circuit reservoir VB with float and level sensor NS, which can be integrated in a central open-loop and closed-loop control unit ECU. The filling level sensor NS should likewise have a redundant configuration and continuously measure the filling level, since in this way a loss of volume due to a leak can be detected quickly. Since in this case the connection to master brake cylinder HZ is omitted and therefore the fallback level in the event of failure of both pressure supply devices DV1 and DV2 and/or the vehicle electrical system with respect to master brake cylinder HZ is also omitted, valves BP1 and BP2 are preferably designed as valves which open when de-energized.

List of reference numerals

1 to 11 hydraulic lines

BK1 first brake circuit

BK2 second brake circuit

HZ master cylinder

BP1 bypass valve 1(SO) or connection switch valve

BP2 bypass valve 2(SO) or connection switch valve

VB memory

WS stroke simulator

WA stroke simulator closing valve

ECU electric control unit

DV pressure supply

DG pressure transducer

D1-D7 seal

AV1, AV2 outlet valve (SG)

ZAV Central Outlet valve (SG)

SV switch valve (SO)

RZ wheel cylinder

RB 1-RB 4 wheel brake

NV liquid level changer

PD1 switch valve (SG)

Open when SO is off

Turn off when SG is power off

SV suction valve

RV check valve

KWS force-stroke measuring element

Sp has a shaft of a ball screw drive KGT

Ko piston

Dr throttle valve

D damper element

PS pedal stroke sensor

P pedal actuation

NS liquid level sensor

TV isolating valve

V1-V4 double-acting piston valve

VL Hydraulic connection line for connecting two brake circuits BK1 and BK2

VLa is used for connecting two internal connecting pipelines of the connecting switch valves BP1 and BP2

Pressure relief valve