Operating method and control device for brake system equipped with brake-actuating hydraulic unit and ESP hydraulic unit for vehicle

Abstract

The invention relates to a control device (50) for a brake system of a vehicle, which brake system is equipped with a brake execution hydraulic unit (30) and an ESP hydraulic unit (32), and to a method for operating a brake system of a vehicle, which brake system is equipped with a brake execution hydraulic unit (30) and an ESP hydraulic unit (32), the method is implemented by reading out or checking, on the basis of the at least one signal (52), whether at least one predetermined fault state is present on the brake-actuating hydraulic unit (30) mounted on the ESP hydraulic unit (32), and if it is determined that at least one predetermined fault state is present on the brake-actuating hydraulic unit (30) taking into account the at least one signal (52), determining that the at least one predetermined fault state is present on the brake-actuating hydraulic unit (30). If so, at least one of the following steps is carried out: activating at least one pump (40) of an ESP hydraulic unit (32) in order to draw a fixed predetermined or determined volume of brake fluid from a brake fluid reservoir (54) of the brake system and / or actuating at least one electric motor (48) of the vehicle, which can be operated in a regenerative mode, the motor braking torque (Bmotor) acts on at least one wheel of the vehicle and / or at least one axle of the vehicle. The motor braking torque (Bmotor) is fixed, predetermined or determined and is not equal to zero.

Description

Technical Field

[0001] The present invention relates to a control device for a brake system of a vehicle equipped with a brake actuator hydraulic unit and an ESP hydraulic unit. The present invention also relates to an ESP hydraulic unit for a brake system of a vehicle additionally equipped with a brake actuator hydraulic unit and a brake system for a vehicle. The present invention also relates to an operating method for a brake system of a vehicle equipped with a brake actuator hydraulic unit and an ESP hydraulic unit. Background Art

[0002] Figure 1 A conventional braking system is shown, which is prior art known to the applicant.

[0003] exist Figure 1 The conventional brake system schematically shown in FIG. 1 has a hydraulic system 10 in which a master brake cylinder 12 and an ESP system 14 are integrated. For each wheel 16 of a vehicle equipped with a conventional brake system, a wheel brake cylinder 18 is connected to the hydraulic system 10. In addition, a brake fluid reservoir 20, an electromechanical brake booster 22 and a brake pedal 24 are connected to the master brake cylinder 12. The electromechanical brake booster 22 is intended to be used in particular as an actuator / regulator to achieve a driver-assisted or autonomous brake pressure increase in the wheel brake cylinder 18. The ESP system 14, which can be controlled by its control unit 26, is to be understood as a component of a conventional brake system that is designed to perform ABS and / or ESP functions. Summary of the invention

[0004] The present invention provides a control device for a braking system of a vehicle equipped with a brake actuator hydraulic unit and an ESP hydraulic unit having the features of claim 1, an ESP hydraulic unit for a braking system of a vehicle additionally equipped with a brake actuator hydraulic unit having the features of claim 6, a braking system for a vehicle having the features of claim 8, and an operating method for a braking system of a vehicle equipped with a brake actuator hydraulic unit and an ESP hydraulic unit having the features of claim 12.

[0005] Advantages of the present invention

[0006] The present invention provides a feasible solution for improving the use of a brake system designed with an ESP hydraulic unit and a brake actuating hydraulic unit, and thus promotes the application of the brake system. It will become clear from the following description that the present invention makes a brake system designed with an ESP hydraulic unit and a brake actuating hydraulic unit particularly advantageous compared to a conventional brake system having only a single hydraulic unit. The present invention makes it possible, in particular in the event of a functional impairment or failure of the brake actuating hydraulic unit, to use the ESP hydraulic unit and / or at least one electric motor of a vehicle equipped with a corresponding brake system to perform autonomous braking and provide force assistance to the driver of the vehicle in the event of driver-induced braking. Therefore, in these situations where conventional brake systems can usually only use mechanical fallback levels (Rückfallebene) to brake the vehicle, the present invention can still provide the driver with good braking comfort.

[0007] Preferably, if the control device determines that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit by taking into account at least one signal, the control device is designed and / or programmed to determine a target volume for the volume of brake fluid to be pumped from the brake fluid reservoir by taking into account at least one sensor signal of at least one brake actuating element sensor of the brake system and / or the ESP hydraulic unit and / or at least one pressure sensor of the brake actuating hydraulic unit, and then activate at least one pump of the ESP hydraulic unit to pump a volume of brake fluid from the brake fluid reservoir corresponding to the determined target volume. The braking effected in this way can thus be adapted to the current braking request.

[0008] Alternatively or additionally, if the control device determines that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit by taking into account at least one signal, the control device is also designed and / or programmed to determine a target braking torque for the motor braking torque to be applied to at least one wheel and / or at least one axle by taking into account at least one sensor signal of at least one brake actuating element sensor of the brake system and / or the ESP hydraulic unit and / or at least one pressure sensor of the brake actuating hydraulic unit, and then to control at least one electric motor to generate a motor braking torque corresponding to the determined target braking torque acting on at least one wheel and / or at least one axle. Thus, the active operation of the at least one electric motor can also be adapted to the current braking request.

[0009] In an advantageous embodiment, the control device is designed and / or programmed to detect, as a function of at least one signal, a functional impairment and / or failure of a brake booster of a brake actuating hydraulic unit, a functional impairment and / or failure of at least one valve of a brake actuating hydraulic unit, a functional impairment and / or failure of at least one sensor device of a brake actuating hydraulic unit, and / or a functional impairment and / or failure of at least a first power supply of a brake booster of a brake actuating hydraulic unit, at least one valve of a brake actuating hydraulic unit, and / or at least one sensor device of a brake actuating hydraulic unit as at least one predetermined fault state. Thus, the embodiment of the control device described here can activate / control the ESP hydraulic unit and / or at least one regeneratively operated electric motor in various fault states of the brake actuating hydraulic unit in order to provide force assistance to driver-induced braking and / or to perform / continue autonomous braking. Thus, fault states for which only a mechanical fallback level can be used conventionally can be advantageously bridged at least temporarily using the embodiment of the control device described here.

[0010] Preferably, at least as long as at least one predetermined fault state is not present at the brake actuating hydraulic unit, the control device is designed and / or programmed to detect wheel locking by at least one of the wheel brake cylinders based on at least one measurement signal of at least one speed sensor of at least one wheel of the vehicle and, if necessary, to switch at least one valve of the ESP hydraulic unit to its open state so that brake fluid can be discharged from the at least one locked wheel brake cylinder through the at least one valve switched to open. Thus, the embodiment of the control device described here can also bring about a cancellation of wheel locking in addition to its advantageous properties explained above.

[0011] The above-mentioned advantages are also achieved with an ESP hydraulic unit for a brake system of a vehicle having such a control device, which is at least additionally equipped with a brake actuating hydraulic unit.

[0012] For example, the ESP hydraulic unit may comprise at least one high-pressure switching valve, via which the respective suction side of at least one pump of the ESP hydraulic unit is hydraulically connected or connectable to a brake fluid reservoir of the brake system, wherein the control device is additionally designed and / or programmed to switch the at least one high-pressure switching valve to its open state during active operation of the at least one pump in order to draw a brake fluid volume from the brake fluid reservoir. This enables a rapid transfer of a brake fluid volume from the brake fluid reservoir, in particular into the ESP hydraulic unit.

[0013] The above advantages are also achieved in a vehicle brake system having a corresponding ESP hydraulic unit, a brake actuating hydraulic unit installed on the ESP hydraulic unit, and wheel brake cylinders installed on the ESP hydraulic unit.

[0014] In an advantageous embodiment of the braking system, the brake actuating hydraulic unit is connected to or can be connected to a first power supply, and the ESP hydraulic unit is connected to or can be connected to a second power supply. Thus, even in the event of failure of the first power supply, which significantly limits the functionality of the brake actuating hydraulic unit, the ESP hydraulic unit can still be used to perform / continue autonomous braking and / or to provide force assistance for driver-induced braking.

[0015] Preferably, the brake actuating hydraulic unit has control electronics which are designed and / or programmed to actuate at least the brake booster of the brake actuating hydraulic unit at least taking into account a brake actuating element sensor of the brake system and / or at least one pressure sensor of the brake actuating hydraulic unit. Thus, during normal operation of the brake system, in which no fault state exists at the brake actuating hydraulic unit, the control electronics can be used to relieve the load on advantageous control devices of the brake system.

[0016] In another advantageous embodiment of the brake system, the brake booster of the brake actuating hydraulic unit is a brake booster located upstream of the master brake cylinder of the brake actuating hydraulic unit or a motorized piston-cylinder device integrated into the hydraulic system of the brake actuating hydraulic device. In both cases, the brake booster can be used during normal operation of the brake system equipped with the brake booster, when there is no fault state at the brake actuating hydraulic unit, to perform autonomous braking and / or to provide force assistance for driver-induced braking, while during periods when the brake booster cannot be used, it can be advantageously bridged at least temporarily by the ESP hydraulic unit for this purpose.

[0017] Furthermore, a corresponding method for operating a brake system for a vehicle equipped with a brake actuation hydraulic unit and an ESP hydraulic unit also produces the above advantages. It is expressly pointed out that the method can be improved according to the above embodiments of the control device, the ESP hydraulic unit and / or the brake system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features and advantages of the present invention are described below with reference to the accompanying drawings.

[0019] Figure 1 A conventional braking system is shown;

[0020] FIG2 shows a schematic diagram of a brake system equipped with a brake actuator hydraulic unit and an ESP hydraulic unit to illustrate an embodiment of the control device; and

[0021] Figure 3a to Figure 3c A flow chart and a coordinate system are shown for explaining an embodiment of a method for operating a brake system for a vehicle which is equipped with a brake actuating hydraulic unit and an ESP hydraulic unit. DETAILED DESCRIPTION

[0022] FIG. 2 shows a schematic diagram of a brake system equipped with a brake actuating hydraulic unit and an ESP hydraulic unit in order to explain the specific embodiment of the control device.

[0023] The brake system schematically shown in FIG. 2 has a brake actuation hydraulic unit 30 and an ESP hydraulic unit 32. The brake actuation hydraulic unit 30 is to be understood as a unit manufactured separately from the ESP hydraulic unit 32, which may also be referred to as a brake actuation hydraulic module 30 or a brake actuation hydraulic subassembly 30. The brake actuation hydraulic unit 30 is equipped with at least one master brake cylinder 34 and a brake booster 36, wherein the brake actuation hydraulic unit 30 is connected or mounted to the ESP hydraulic unit 32 only after its manufacture. It is clear from the following description that, due to the high safety standards of the brake system when performing autonomous braking, the brake system is optionally equipped with a brake operating element 38 connected to the master brake cylinder 34, such as a brake pedal 38.

[0024] The ESP hydraulic unit 32 can also be understood as a unit that is manufactured separately from the brake actuating hydraulic unit 30 and can be described as an ESP hydraulic module 32 or an ESP hydraulic subassembly 32. Hydraulic components, such as, in particular, at least one pump 40, are integrated into the ESP hydraulic unit 32, by means of which ABS and / or ESP functions can be implemented at the brake system of FIG.

[0025] In addition to the brake actuating hydraulic unit 30 and the ESP hydraulic unit 32, the brake system is also equipped with wheel brake cylinders 42, which are connected / mounted to the ESP hydraulic unit 32. The total number of wheel brake cylinders 42 of the brake system can correspond to the total number of wheels of the vehicle to be equipped / equipped with the brake system. It is pointed out that the usability of the brake system is not limited to a specific vehicle type / motor vehicle type of vehicle / motor vehicle equipped with the brake system, nor to a specific total number of wheels of the vehicle / motor vehicle.

[0026] Merely by way of example, the brake system of FIG. 2 has two brake circuits 44 a and 44 b. Furthermore, mere by way of example, the hydraulic units 30 and 32 are connected to one another via a brake line 46 of each brake circuit 44 a and 44 b, respectively. The hydraulic connection of the two hydraulic units 30 and 32 schematically shown in FIG. 2 should be interpreted merely as an example.

[0027] 2 also shows a control device 50 that is designed and / or programmed to determine whether at least one predetermined fault state exists at the brake actuating hydraulic unit 30. The at least one predetermined fault state that may exist at the brake actuating hydraulic unit 30 is determined by checking or reading at least one signal 52 provided to the control device 50 (an example of the at least one signal 52 read and / or checked by the control device 50 will also be mentioned below).

[0028] If necessary, i.e. if the control device 50 determines, taking into account the at least one signal 52, that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit 30, the control device 50 is designed and / or programmed to carry out at least one of the two measures explained below. For example, the control device 50 can be designed and / or programmed to activate, as a first measure, at least by means of at least one first control signal 40s, at least one pump 40 of the ESP hydraulic unit 32 in order to suck a fixed predetermined or determined brake fluid volume from a brake fluid reservoir 54 of the brake system. Preferably, the brake fluid reservoir 54 from which the brake fluid volume additionally sucked into the brake circuits 44a and 44b is taken is a brake fluid reservoir 54 which is connected to the master brake cylinder 34, in particular via at least one vent.

[0029] By sucking an additional volume of brake fluid from brake fluid reservoir 54 (measure 1), wheel brake cylinders 42 are additionally filled. Measure 1 can therefore provide force assistance for driver-induced braking despite a functional impairment or failure of brake actuating hydraulic unit 30. Driver-induced braking is understood to be braking requested by the driver through a driver braking force (not equal to zero) applied by the driver to brake actuating element 38. However, autonomous braking of the vehicle can also be implemented or continued by measure 1. Autonomous braking is also understood to be braking requested by an automatic speed control system of the vehicle, wherein the driver does not actuate brake actuating element 38. An automatic speed control system can be, for example, a cruise control system or an emergency brake system.

[0030] It should also be noted here that the possibility of sucking additional brake fluid volume from brake fluid reservoir 54 as required by control device 50 generally enables a reduction in the size of master brake cylinder 34. Therefore, an advantageous design / programming of control device 50 facilitates miniaturization of the brake system of FIG.

[0031] Alternatively or in addition, the control device 50 can also be designed and / or programmed to control, as a second measure, at least one electric motor 48 of a vehicle equipped with a brake system by means of at least one second control signal 48s to generate a fixed predetermined or determined by the control device 50 motor braking torque not equal to zero acting on at least one wheel of the vehicle and / or at least one axle of the vehicle. The at least one electric motor 48 is to be understood as a motor that can be operated in its regenerative mode so that the vehicle can brake / be braked by means of a motor braking torque acting on at least one wheel and / or at least one axle. The at least one electric motor 48 can in particular be a drive motor of the vehicle that can be operated in a regenerative mode.

[0032] Therefore, even if the brake actuating hydraulic unit 30 is functionally impaired or fails, measure 2 enables the combined use of at least one electric motor 48 to brake the vehicle. By controlling the at least one electric motor 48 according to measure 2, force assistance can be provided to the driver during driver-induced braking, for which the vehicle is braked using the motor braking torque of the at least one electric motor 48 in addition to the friction braking torque applied by the wheel brake cylinders 42. In addition, even if the brake actuating hydraulic unit 30 is functionally impaired or fails, measure 2 allows the at least one electric motor 48 to be used to continue or perform autonomous braking by means of the motor braking torque applied to at least one wheel and / or at least one axle of the vehicle.

[0033] Thus, the advantageous design / programming of the control device 50 enables an advantageous possibility, so that despite a functional impairment or failure of the brake actuating hydraulic unit 30, force assistance can still be provided for the braking caused by the driver and / or autonomous braking can be continued or performed. Thus, the advantageous design / programming of the control device 50 enables an extension of the conventional emergency function, in particular, even in the event of a complete failure of the brake booster 36 usually used for this purpose, force assistance can still be provided for the braking caused by the driver and / or autonomous braking can be continued or performed. For conventional brake systems, in the event of a complete failure of their brake booster, force assistance for the braking caused by the driver is usually no longer possible and autonomous braking must be interrupted immediately, which disadvantages are eliminated by using the control device 50 for the type of brake system described here. It should also be pointed out here that even if there is a significant functional impairment of the brake actuating hydraulic unit 30, the brake system of FIG. 2 does not have to be operated at its mechanical fallback level, because the above-mentioned possibility can still be used by the control device 50 and the ESP hydraulic unit 32 to provide force assistance for the braking caused by the driver and / or to continue or perform autonomous braking.

[0034] 2 equipped with control device 50 has an advantageously high safety standard in particular when performing autonomous braking. It is therefore also possible to dispense with equipping the brake system with its brake actuating element 38 .

[0035] Preferably, the control device 50 is designed and / or programmed to determine a target volume for the volume of brake fluid to be pumped from the brake fluid reservoir 54 if the control device 50 determines, taking into account the at least one signal 52, that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit 30. The target volume can be determined as a function of a braking request indicated by the driver by his actuation of the brake actuating element 38, for which purpose the target volume is determined taking into account at least one sensor signal 56 of at least one brake actuating element sensor 58 of the brake system and / or at least one pressure sensor 60 and 62 of the ESP hydraulic unit 30 and / or the brake actuating hydraulic unit 32. The control device 50 can then activate / control the at least one pump 40 of the ESP hydraulic unit 32 in order to pump a volume of brake fluid from the brake fluid reservoir 54 corresponding to the determined target volume. Since the target volume is determined taking into account the at least one sensor signal 56 in the driver-induced braking, the force assistance achieved is a metered boost of the driver-induced braking according to the driver's braking request. Thus, even in the case of autonomous braking, the determination of the target volume taking into account the at least one sensor signal 56 makes it possible to reliably comply with the braking request of the automatic speed control system. By means of the process described here, the brake pressure in wheel brake cylinder 42 is always increased in accordance with the automatic speed control system or the driver's braking request when the brake fluid volume is drawn from brake fluid reservoir 54, so that the driver will not / hardly regard the resulting brief reaction on brake actuating element 38 as a disturbance.

[0036] Likewise, if the control device 50 determines that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit 30 by taking into account at least one signal 52, the control device can be designed and / or programmed to determine a target braking torque for the motor braking torque to be applied to at least one wheel and / or at least one axle. To determine the target braking torque, at least one sensor signal 56 of at least one brake actuating element sensor 58 and / or at least one pressure sensor 60 and 62 can also be evaluated. If necessary, the control device 50 then controls at least one electric motor 48 to act on at least one wheel and / or at least one axle with a motor braking torque corresponding to the determined target braking torque. In the manner described here, the generated motor braking torque can correspond to the braking request requested by actuating the brake actuating element 38 or the braking request requested by the automatic speed control system, not only when providing force assistance for driver-induced braking, but also when continuing or performing autonomous braking, so that good braking and driving comfort can be ensured despite the functional impairment or failure of the brake actuating hydraulic unit 30.

[0037] The at least one brake actuating element sensor 58 may be, for example, a rod displacement sensor and / or a differential displacement sensor. The at least one pressure sensor 60 and 62 may be a pressure sensor 60 of the brake actuating hydraulic unit 30 connected to the master brake cylinder 34 and / or a pressure sensor 62 of the ESP hydraulic unit 32. Preferably, the control device 50 is designed / programmed to preferentially evaluate at least one sensor signal 56 of the at least one brake actuating element sensor 58 and / or a pressure sensor 60 of the brake actuating hydraulic unit 30 connected to the master brake cylinder 34 for force assistance of driver-initiated braking and / or for continuing or performing autonomous braking, and to (jointly) evaluate the sensor signal 56 of the pressure sensor 62 of the ESP hydraulic unit 32 only when there is a high probability that at least one function of the at least one brake actuating element sensor 58 and / or a pressure sensor 60 of the brake actuating hydraulic unit 30 connected to the master brake cylinder 34 is impaired.

[0038] At least one predetermined fault state that can be detected by the control device 50 based on the at least one signal 52 can include, for example, a functional impairment and / or failure of the brake booster 36 of the brake actuating hydraulic unit 30. A functional impairment or failure of the brake booster 36 can be detected, for example, based on an evaluation or comparison of at least one signal 52 of at least one brake operating element sensor 58 and / or a pressure sensor 60 of the brake actuating hydraulic unit 30 connected to the master brake cylinder 34 with a pressure sensor 62 of the ESP hydraulic unit 32 and / or a pressure sensor 64 of the brake actuating hydraulic unit 30 connected to the brake booster 36. In order to check / verify the brake booster 36, at least one signal 52 of a motor current sensor of the brake booster 36 and / or a rotation angle sensor 66 of the brake booster 36 can also be (jointly) evaluated. Impairment of the function and / or failure of at least one valve of brake actuating hydraulic unit 30 can also be detected as a predetermined fault state by evaluating or comparing at least one signal 52 of at least one brake actuating element sensor 58, at least one pressure sensor 60, 62 and 64 of brake actuating hydraulic unit 30 and / or ESP hydraulic unit 32, a motor current sensor and / or a rotation angle sensor 66. Impairment of the function and / or failure of at least one sensor device of brake actuating hydraulic unit 30, for example at least one of its pressure sensors 60 and 64, can likewise be detected as a predetermined fault state by evaluating or comparing at least one signal 52 of at least one brake actuating element sensor 58, at least one pressure sensor 60, 62 and 64 of brake actuating hydraulic unit 30 and / or ESP hydraulic unit 32, a motor current sensor and / or a rotation angle sensor 66. Furthermore, impairment of the function or failure of the first power supply unit can be determined as a predetermined fault state based on at least one signal 52 of a current sensor (not shown) of the first power supply unit, which is electrically connected to at least the brake booster 36, at least one valve of the brake actuating hydraulic unit 30, and / or at least one sensor device of the brake actuating hydraulic unit 30. Therefore, various fault states of the brake actuating hydraulic unit 30 can be reliably detected by a sensor mechanism that is already conventionally used on the vehicle.

[0039] The control device 50 can be, in particular, the control device 50 of the ESP hydraulic unit 32. Preferably, the control device 50 is designed and / or programmed to detect wheel lock and, if necessary, to cancel the wheel lock, at least as long as a single predetermined fault state or at least one of the predetermined fault states is not present at the brake actuating hydraulic unit 30. A possible wheel lock can be detected based on at least one measurement signal of at least one (not shown) speed sensor of at least one wheel of the vehicle. In this way, it can be reliably detected whether one of the wheels of the vehicle is locked by at least one of the wheel brake cylinders 42. If a wheel lock is detected, at least one wheel outlet valve 68 of the ESP hydraulic unit 32 can be switched to its open state by the control device 50, so that brake fluid is discharged from the at least one wheel brake cylinder 42 that is locked through the at least one wheel outlet valve 68 that is switched to open. Thus, the control device 50 can also be used to control / activate a "conventional" ABS and / or ESP function of the ESP hydraulic unit 32. Optionally, the control device 50 can also be designed / programmed to control / activate other auxiliary functions or auxiliary sub-functions.

[0040] In the brake system of FIG. 2 , the brake booster 36 of the brake actuating hydraulic unit 30 is, for example, a motorized piston-cylinder device 36 integrated into the hydraulic system of the brake actuating hydraulic unit 30. The motorized piston-cylinder device 36 may also be referred to as a plunger device 36 or an electric brake booster 36 decoupled from the master brake cylinder 34. Therefore, the brake actuating hydraulic unit 30 equipped with a motorized piston-cylinder device 36 may also be described as a DPB (Decoupled Power Brake) hydraulic unit 30. Alternatively, however, the brake booster 36 of the brake actuating hydraulic unit 30 may also be a brake booster located upstream of the master brake cylinder 34 of the brake actuating hydraulic unit 30, such as, in particular, an electromechanical brake booster (iBooster).

[0041] As long as there is no single predetermined fault state or at least one of the predetermined fault states at the brake actuating hydraulic unit 30, the driver's braking of the wheel brake cylinders 42 can be prevented by controlling the simulator isolation valve 70 and keeping it in its open state, via which the simulator 72 is connected to the master brake cylinder 34. When the driver brakes in the simulator 72 by actuating the brake actuating element 38 via the opened simulator isolation valve 70, the driver-induced braking can be selectively realized by the motorized piston-cylinder device 36, by at least one electric motor 48 of the vehicle that can be operated in its regenerative mode, or by the motorized piston-cylinder device 36 and at least one electric motor 48. In all the possible solutions described here for realizing driver-induced braking, the driver who brakes in the simulator 72 always has a standard brake actuation feel / pedal feel.

[0042] The brake actuating hydraulic unit 30 can also optionally have a first isolating valve 74 and a second isolating valve 76 for each brake circuit 44a and 44b, respectively, the associated brake circuit 44a or 44b being connected to the master brake cylinder 34 via the first isolating valve, and the associated brake circuit 44a or 44b being connected to the motorized piston-cylinder device 36 serving as a brake booster 36 via the second isolating valve. Optionally, the motorized piston-cylinder device 36 can also be connected to the brake fluid reservoir 54 via a further isolating valve 78 of the brake actuating hydraulic unit 30. In addition, at least one suction line 80 with an overpressure valve 82 can be configured in the brake actuating hydraulic unit 30, via which the brake line 46 is connected to the brake fluid reservoir 54. Optionally, the brake actuating hydraulic unit 30 may also have a (own) control electronics 84, which is designed and / or programmed to actuate at least the brake booster 36 of the brake actuating hydraulic unit 30, at least taking into account the brake operating element sensor 58 of the brake system and / or at least one pressure sensor 60 of the brake actuating hydraulic unit 30. The control electronics 84 can thus relieve the workload of the control device 50. Preferably, the control device 50 and the control electronics 84 are designed / programmed to communicate with each other, for example via bus communication.

[0043] The ESP hydraulic unit 32 may also include at least one wheel inlet valve 86 in addition to its at least one wheel outlet valve 68. Alternatively or additionally, the ESP hydraulic unit 30 may also have at least one high-pressure switching valve 88 and / or at least one switching valve 90. If the respective suction side of at least one pump 40 of the ESP hydraulic unit 32 is hydraulically connected or can be hydraulically connected to the brake fluid reservoir 54 of the brake system via at least one high-pressure switching valve 88, the control device 50 may additionally be designed and / or programmed to switch the at least one high-pressure switching valve 88 to its open state during the active operation of the at least one pump 40 in order to draw an additional brake fluid volume from the brake fluid reservoir 54. Furthermore, at least one storage chamber 94 of the ESP hydraulic unit 32 may be connected to the respective suction side of the at least one pump 40 via an overpressure valve 92. If the brake actuating hydraulic unit 30 is connected or can be connected to the first power supply, it is preferably connected to the second power supply for the ESP hydraulic unit 32. Even if the first power supply fails completely, the control device 50 and the ESP hydraulic unit 32 can still perform the advantageous ride-through function explained above in this case.

[0044] The use of the control device 50 enables significantly higher degrees of freedom in the hydraulic design of a brake system equipped with / interacting with the control device. In this way, it can be ensured in particular that a specific brake system type can be used for a variety of vehicle types / motor vehicle types.

[0045] Figure 3a to Figure 3c A flow chart and a coordinate system are shown for explaining an embodiment of a method for operating a brake system for a vehicle which is equipped with a brake actuating hydraulic unit and an ESP hydraulic unit.

[0046] The feasibility of the method described below is neither limited to a specific vehicle type / motor vehicle type of vehicle / motor vehicle equipped with the braking system nor to a specific total number of wheels of the vehicle / motor vehicle.

[0047] In method step S1 , it is read out or checked based on at least one signal whether at least one predetermined fault state is present at the brake actuating hydraulic unit. Examples of the at least one signal and the at least one predetermined fault state have already been mentioned above.

[0048] If it is determined according to the at least one signal that the brake actuating hydraulic unit does not have at least one predetermined fault state, the brake system is operated according to the Figure 3b The coordinate system shows the normal operation mode. Figure 3b The horizontal axis of the coordinate system is the time axis t, and Figure 3b The ordinate of the coordinate system shows the braking torque B.

[0049] In by Figure 3b In the schematically shown normal operating mode, the driver of the vehicle requests the vehicle to brake by actuating a brake actuating element of the brake system. In method step S2, the driver's braking request is determined based on at least one sensor signal of at least one brake actuating element sensor of the brake system and / or at least one pressure sensor of the ESP hydraulic unit and / or the brake actuating hydraulic unit. In particular, if the brake booster of the brake actuating hydraulic unit is a motorized piston-cylinder device integrated into the hydraulic system of the brake actuating hydraulic unit 30, the master brake cylinder pressure present in the master brake cylinder of the brake actuating hydraulic unit can be determined / estimated to determine the driver's braking request.

[0050] In the embodiment of the method described here, the motorized piston-cylinder device used as brake booster has little or no influence on the master brake cylinder pressure. The master brake cylinder pressure is therefore (almost) only caused by the driver. pMC The braking torque B of the wheel cylinders of the brake system "caused only by the driver" is shown. pMC , this braking torque will act on the vehicle when the master brake cylinder pressure dominates in all wheel brake cylinders. Figure 3bAs can be seen from the coordinate system of , in normal operation, the brake booster is controlled in method step S3 such that the wheel brake cylinders of the brake system exert a significantly increased friction braking torque B on the wheels of the vehicle due to the volume additionally displaced into the wheel brake cylinders by the operation of the brake booster. friction . Friction braking torque B friction In particular, it can correspond to a braking torque B "caused only by the driver" pMC The product of the booster factor greater than 1. Then the total braking torque B total The vehicle is braked with a total braking torque (essentially) corresponding to the friction braking torque B of the wheel brake cylinders. friction .

[0051] Figure 3c The abscissa and ordinate of the coordinate system also represent the time axis t and the braking torque B. Figure 3c The coordinate system of shows what happens when in method step S1 it is determined from at least one signal that at least one of a single fault state or a predetermined fault state exists at the brake actuating hydraulic unit. If necessary, at least one of method steps S4 and S5 is performed.

[0052] For example, as method step S4, at least one pump of the ESP hydraulic unit can be activated to draw a fixed predetermined or determined brake fluid volume from the brake fluid reservoir of the brake system. By drawing in an additional brake fluid volume, an additional brake pressure buildup is achieved in the wheel brake cylinders, thereby increasing the friction braking torque B of the wheel brake cylinders. friction .

[0053] However, in the embodiment described here, if in method step S1 a single fault state or one of the predetermined fault states is detected at the brake actuating hydraulic unit, method step S5 is performed. As method step S5, at least one electric motor of the vehicle that can be operated in a regenerative mode is controlled to generate a fixed predetermined or determined motor braking torque B that is not equal to zero and acts on at least one wheel of the vehicle and / or at least one axle of the vehicle. motor Therefore, by executing method step S5, the total braking torque B total This is not only generated purely hydraulically, but also by at least one electric motor acting as a generator. When generating high deceleration values, this leads to a longer volume sufficiency in the master brake cylinder. Furthermore, method step S5 can be carried out without causing negative reactions to the driver, such as noise or movement of the brake operating element / brake pedal.

[0054] Preferably, method step S6 is performed between the detection of the presence of a single fault state or one of the predetermined fault states at the brake actuating hydraulic unit and at least one of method steps S4 or S5. In method step S6, a target volume of the brake fluid volume to be pumped in method step S4 and / or a motor braking torque B to be applied to at least one wheel and / or at least one axle can be determined taking into account at least one sensor signal of at least one brake actuating element sensor of the brake system and / or the ESP hydraulic unit and / or at least one pressure sensor of the brake actuating hydraulic unit. motor The target braking torque is Figure 3c It can be seen from the coordinate system that the friction braking torque B of the wheel brake cylinder friction The motor braking torque B of at least one electric motor motor The total braking torque B applied by the sum of total This also corresponds to the braking torque B "caused only by the driver" pMC Multiply by a booster factor greater than 1.

[0055] Having self-recognized the presence of a single fault state or one of the predetermined fault states at the brake actuating hydraulic unit and therefore at the start of braking, at least one electric motor used as a generator can be selectively used to perform method step S5. Preferably, however, the execution of method step S5 is waited until hydraulic volume can no longer be drawn from the brake fluid reservoir of the brake system by performing method step S4. In this way, linear boosting can be achieved without cyclically checking the driver's request.

Claims

1. A control device (50) for a brake system of a vehicle equipped with a brake actuation hydraulic unit (30) and an ESP hydraulic unit (32), It is characterized in that The control device (50) is designed and / or programmed to read out or check whether at least one predetermined fault state exists at the brake actuating hydraulic unit (30) installed at the ESP hydraulic unit (32) based on at least one signal (52) provided to the control device (50), Wherein, if the control device (50) determines, taking into account the at least one signal (52), that a single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit (30), the control device (50) is additionally designed and / or programmed to: - activating at least one pump (40) of the ESP hydraulic unit (32) in order to draw a fixed, predetermined or determined volume of brake fluid from a brake fluid reservoir (54) of the brake system, and / or - actuating at least one electric motor (48) of the vehicle which can be operated in a regenerative mode in order to generate a motor braking torque (B) which is not equal to zero and which is fixed or determined by the control device (50) and acts on at least one wheel of the vehicle and / or at least one axle of the vehicle motor ).

2. The control device (50) according to claim 1, wherein: If the control device (50) determines, taking into account the at least one signal (52), that the single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit (30), the control device (50) is designed and / or programmed to determine a target volume of brake fluid to be pumped from the brake fluid reservoir (54) taking into account at least one brake operating element sensor (58) of the brake system and / or at least one sensor signal (56) of the ESP hydraulic unit (32) and / or at least one pressure sensor (60, 62) of the brake actuating hydraulic unit (30), and then activates at least one pump (40) of the ESP hydraulic unit (32) to pump a brake fluid volume from the brake fluid reservoir (54) corresponding to the determined target volume.

3. The control device (50) according to claim 1 or 2, wherein: If the control device (50) determines, taking into account the at least one signal (52), that the single predetermined fault state or at least one of the predetermined fault states is present at the brake actuating hydraulic unit (30), the control device (50) is designed and / or programmed to determine, taking into account at least one sensor signal (56) of at least one brake actuating element sensor (58) of the brake system and / or at least one pressure sensor (60, 62) of the ESP hydraulic unit (32) and / or the brake actuating hydraulic unit (30), the motor braking torque (B) to be applied to at least one wheel and / or at least one axle. motor ), and then controlling the at least one electric motor (48) to generate a motor braking torque (B) acting on the at least one wheel and / or the at least one axle corresponding to the determined target braking torque. motor ).

4. A control device (50) according to any one of the preceding claims, wherein: The control device (50) is designed and / or programmed to identify, based on the at least one signal (52), functional impairment and / or failure of the brake booster (36) of the brake actuating hydraulic unit (30), functional impairment and / or failure of at least one valve of the brake actuating hydraulic unit (30), functional impairment and / or failure of at least one sensor device of the brake actuating hydraulic unit (30), and / or functional impairment and / or failure of at least the brake booster (36) of the brake actuating hydraulic unit (30), at least one valve of the brake actuating hydraulic unit (30) and / or functional impairment and / or failure of the first power supply unit of at least one sensor device of the brake actuating hydraulic unit (30) as the at least one predetermined fault state.

5. A control device (50) according to any one of the preceding claims, wherein: At least as long as the at least one predetermined fault state is not present at the brake actuating hydraulic unit (30), the control device (50) is designed and / or programmed to detect wheel locking caused by at least one of the wheel brake cylinders (42) based on at least one measurement signal of at least one speed sensor of at least one wheel of the vehicle and, if necessary, to switch at least one valve (68) of the ESP hydraulic unit (32) to its open state so that brake fluid can be discharged from the at least one wheel brake cylinder (42) that is locked through the at least one valve (68) that is switched to open.

6. An ESP hydraulic unit (32) for a brake system of a vehicle which is additionally equipped with a brake actuating hydraulic unit (30) having a control device (50) according to any of the preceding claims.

7. The ESP hydraulic unit (32) according to claim 6, wherein: The ESP hydraulic unit (32) comprises at least one high-pressure switching valve (88), via which the respective suction side of at least one pump (40) of the ESP hydraulic unit (32) is hydraulically connected or can be hydraulically connected to a brake fluid reservoir (54) of the brake system, and wherein the control device (50) is additionally designed and / or programmed to switch the at least one high-pressure switching valve (88) to its open state during active operation of the at least one pump (40) in order to draw the brake fluid volume from the brake fluid reservoir (54).

8. A braking system for a vehicle, the braking system comprising: An ESP hydraulic unit (32) according to claim 6 or 7; a brake actuating hydraulic unit (30) installed at the ESP hydraulic unit (32); and A wheel brake cylinder (42) is installed at the ESP hydraulic device (32).

9. The braking system according to claim 8, wherein: The brake actuating hydraulic unit (30) is connected to a first power supply or can be connected to the first power supply, and the ESP hydraulic unit (32) is connected to a second power supply or can be connected to the second power supply.

10. The braking system according to claim 8 or 9, wherein: The brake actuating hydraulic unit (30) has control electronics (84) which are designed and / or programmed to actuate at least a brake booster (36) of the brake actuating hydraulic unit (30) taking into account at least a brake operating element sensor (58) of the brake system and / or at least one pressure sensor (60, 64) of the brake actuating hydraulic unit (30).

11. The brake system according to claim 10, wherein: The brake booster (36) of the brake actuating hydraulic unit (30) is a brake booster upstream of a master brake cylinder (34) of the brake actuating hydraulic unit (30) or a motorized piston-cylinder device (36) integrated into the hydraulic system of the brake actuating hydraulic unit (30).

12. Method for operating a brake system for a vehicle equipped with a brake actuation hydraulic unit (30) and an ESP hydraulic unit (32), It is characterized by the following steps: reading or checking, based on at least one signal (52), whether at least one predetermined fault state exists at the brake actuating hydraulic unit (30) installed at the ESP hydraulic unit (32), and If it is determined that the at least one predetermined fault state exists at the brake actuating hydraulic unit (30) taking into account the at least one signal (52), at least one of the following steps is performed: - activating at least one pump (40) of the ESP hydraulic unit (32) in order to draw a fixed, predetermined or determined volume of brake fluid from a brake fluid reservoir (54) of the brake system; and / or - actuating at least one electric motor (48) of the vehicle which can be operated in a regenerative mode in order to generate a fixed predetermined or determined motor braking torque (B) which is not equal to zero and acts on at least one wheel of the vehicle and / or at least one axle of the vehicle motor ).

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