Control device and returning method for vehicle brake system

Abstract

To reduce noise when brake fluid is returned from a storage chamber of a brake system to a master brake cylinder.SOLUTION: During the return time interval, a pump control signal can be output to a pump motor (20) of a piston pump (18) of a brake circuit (14), thereby transferring brake fluid from a storage chamber (22) of the brake circuit (14). Valve control signals each having non-zero current intensity can be output to a circuit pressure control valve (16) constantly controllable during the return time interval and open at the non-energized timing, thereby allowing the circuit pressure control valve (16) to be temporarily shifted and / or maintained to a closed state during the return time interval based on the generated closing force. The brake fluid can be transferred to a master brake cylinder (12) via the circuit pressure control valve (16) pressed for a short time several times and brought into a partially open state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a brake system of a vehicle. The invention also relates to a brake system for a vehicle. Furthermore, the invention relates to a return method for a brake system of a vehicle. [Background technology]

[0002] In the patent document 1, a conventional method for emptying a reservoir is described, in which at least one pump motor of at least one piston pump of a brake system of a vehicle is controlled by at least one pump control signal such that brake fluid is transferred from at least one reservoir of at least one brake circuit equipped with at least one piston pump based on the operation of the at least one piston pump caused by the at least one pump control signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] DE 102018200748 Summary of the Invention

[0004] The present invention provides a control device for a vehicle brake system having the features of claim 1, a control device for a vehicle brake system having the features of claim 5, a brake system for a vehicle having the features of claim 11, a return method for a vehicle brake system having the features of claim 12, and a return method for a vehicle brake system having the features of claim 13.

[0005] The present invention provides a possibility for returning brake fluid from at least one reservoir of a vehicle's brake system to a master brake cylinder of the brake system with less noise than the above-mentioned prior art. In particular, during a return time interval, i.e. during the return / readjustment of brake fluid from at least one reservoir of the brake system to the master brake cylinder, pressure pulsations of at least one used piston pump are damped by actuating at least one circuit pressure control valve of the brake system by outputting at least one valve control signal. Thus, the undesirable noises that previously occurred in the prior art due to pressure pulsations of at least one piston pump can be damped or prevented during the return.

[0006] Since the present invention is purely control-based, in many cases it is sufficient to reprogram the control electronics of the respective brake system for its use. There is no need to modify or expand the respective hardware of the brake system that utilizes the present invention. Therefore, the present invention is inexpensive and can be used without increasing the space required in the vehicle for the respective brake system.

[0007] In an advantageous embodiment of the control device, the electronic device is designed and / or programmed such that the current intensity of each of the at least one valve control signals is set during the return time interval in such a way that the closing force of the at least one circuit pressure control valve can withstand a pressure difference of 3 bar between the brake circuit pressure present in the brake circuit coupled via the respective circuit pressure separation valve and the master brake cylinder pressure present in the master brake cylinder and can be overcome by a pressure difference of 25 bar between the respective brake circuit pressure and the master brake cylinder pressure. Thus, in the embodiment of the control device described herein, the actuation of the at least one circuit pressure control valve during the return time interval is performed with a low current intensity, whereby a significant pressure difference between the respective brake circuit pressure and the master brake cylinder pressure is avoided / prevented. This ensures a reliable "additional filling" / simultaneous filling of the master brake cylinder by the operation of the at least one piston pump during the return time interval.

[0008] For example, the electronic device may be designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal is set such that the provided closing force of the at least one circuit pressure control valve is capable of withstanding a pressure difference of 10 bar between the brake circuit pressure and the master brake cylinder pressure present in the brake circuits coupled via the respective circuit pressure isolation valves and is surmountable by a pressure difference of 25 bar between the respective brake circuit pressure and the master brake cylinder pressure. Use of the control device embodiments described herein ensures reliable delivery of brake fluid from the at least one reservoir to the master brake cylinder.

[0009] Similarly, the electronic device may be designed and / or programmed such that the current intensity of each of the at least one valve control signals during the return time interval is set such that the closing force provided by the at least one circuit pressure control valve is able to withstand a pressure difference of 3 bar between the brake circuit pressure and the master brake cylinder pressure present in the brake circuit coupled via the respective circuit pressure isolation valve and is surmountable by a pressure difference of 15 bar between the respective brake circuit pressure and the master brake cylinder pressure. The actuation of the at least one circuit pressure control valve during the return time interval caused by the embodiments of the control device described herein already provides a closing force sufficient to damp the pressure pulsations of the at least one piston pump. Thus, during the return time interval, it is not / hardly necessary to tolerate the generation of undesirable noise.

[0010] In another advantageous embodiment of the control device, the electronic device is designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal is no more than one third of the maximum current strength that can be maximally delivered by the electronic device to the at least one circuit pressure control valve. In embodiments of the control device described herein, actuation of the at least one circuit pressure control valve is also performed with such a low current strength that no / little significant pressure difference occurs between the brake circuit pressure and the master brake cylinder pressure.

[0011] In particular, the electronic device can be designed and / or programmed such that during the return time interval, the current magnitude of each of the at least one valve control signal is equal to or less than one-fourth of the maximum current magnitude that can be maximally delivered by the electronic device to the at least one circuit pressure control valve. In particular, the electronic device can be designed and / or programmed such that during the return time interval, the current magnitude of each of the at least one valve control signal is equal to or less than one-fifth of the maximum current magnitude that can be maximally delivered by the electronic device to the at least one circuit pressure control valve. In either case, the magnitude of actuation of the at least one circuit pressure control valve during the return time interval is sufficient to sufficiently damp pressure pulsations of the at least one piston pump.

[0012] Alternatively or additionally, the electronic device can be designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal is between 100 mA and 400 mA, such a low current strength of the at least one valve control signal being sufficient to provide a closing force of the at least one circuit pressure control valve, which closing force can dampen the pulsations of the at least one piston pump, but which can be overcome for a short time due to the "top-filling" / simultaneous filling of the master brake cylinder due to the induced operation of the at least one piston pump.

[0013] In an advantageous development, the electronic device can additionally be designed and / or programmed in such a way that during the return time interval, the energization of at least one de-energized, high-pressure switching valve of the brake system, which additionally hydraulically couples the at least one brake circuit to the master brake cylinder, is prevented by the electronic device, so that during the return time interval, the at least one high-pressure switching valve can be respectively brought into and / or maintained in a closed state. Thus, despite the additional coupling of the at least one brake circuit to the master brake cylinder via the at least one high-pressure switching valve, an undesirable outflow of brake fluid from the master brake cylinder via the at least one high-pressure switching valve into the respective brake circuit can be reliably prevented.

[0014] The aforementioned advantages are also ensured in a vehicle brake system comprising a corresponding control device and at least one brake circuit hydraulically connected to a master brake cylinder of the brake system, the brake circuit having at least one constantly controllable and normally open circuit pressure control valve, each controllable by at least one valve control signal of the electronic device of the control device, at least one piston pump including at least one pump motor, each controllable by at least one pump control signal of the electronic device, and at least one reservoir.

[0015] Furthermore, the implementation of a corresponding feedback method for a brake system of a vehicle also provides the above-mentioned advantages.It is expressly mentioned that the feedback method according to the above-mentioned embodiment of the control device can be further developed. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a controller and a braking system cooperating with the controller. [Diagram 2]4 is a flowchart for explaining an embodiment of a return method for a vehicle brake system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Other features and advantages of the present invention will now be described with reference to the accompanying drawings.

[0018] FIG. 1 illustrates a schematic diagram of one embodiment of a controller and a braking system that cooperates with the controller.

[0019] It is noted that the applicability of the control device 10 described below is not limited to a specific brake system type of the associated brake system, nor to a particular vehicle type / automobile type of the vehicle / automobile equipped with the brake system. In particular, the control device 10 can cooperate with (almost) any brake system comprising a master brake cylinder 12 and at least one brake circuit 14, which is formed with at least one constantly controllable and de-energized open circuit pressure control valve 16, at least one piston pump 18 with at least one pump motor 20, and at least one reservoir 22, and is hydraulically coupled to the master brake cylinder 12 via the at least one circuit pressure control valve 16. The at least one circuit pressure control valve 16 can also be understood as a change-over valve 16.

[0020] The control device 10 has an electronic device 10a, which is designed and / or programmed in such a way that during a so-called return time interval, the master brake cylinder pressure present in the master brake cylinder 12 and at least one brake circuit pressure present in the at least one brake circuit 14, respectively, can be / is boosted by emptying at least one storage chamber 22. For this purpose, at least one pump control signal 20s can / is output by the electronic device 10a to at least one pump motor 20 of at least one piston pump 18 during the return time interval. On the basis of the energization of the at least one pump motor 20, which is realized by the respective pump control signal 20s, an operation of the at least one piston pump 18 can / is triggered such that brake fluid can / is transported from at least one storage chamber 22 of the at least one brake circuit 14. The return time interval can therefore also be understood as a pump return phase.

[0021] In order to prevent the generation of undesirable noises during the operation of the at least one piston pump 18 caused by the respective pump control signals 20s, the electronic device 10a is also designed and / or programmed to output, during the return time interval, at least one valve control signal 16s, each having a non-zero current intensity, to at least one circuit pressure control valve 16 of the brake system hydraulically coupling the at least one brake circuit 14 to the master brake cylinder 12. The output of the at least one valve control signal 16s to the at least one circuit pressure control valve 16 can also be translated as an actuation of the at least one circuit pressure control valve 16 based on the respective non-zero current intensity of the valve control signal, whereby the at least one circuit pressure control valve 16 can / is moved to and / or can / is maintained in a respective closed state at least temporarily during the return time interval based on a closing force provided by the respective valve control signal 16s.

[0022] 1 embodiment, the electronic device 10a is designed and / or programmed such that the current intensity of each of the at least one valve control signal 16s during the return time interval is set such that the closing force of the at least one circuit pressure control valve 16 caused by the induced operation of the at least one piston pump 18 can / is overcome for a short time. Thus, the closing force caused by the current intensity of each of the at least one valve control signal 16s is so "weak" that the pressure difference between the brake circuit pressure present in the brake circuit 14 coupled via the respective circuit pressure control valve 16 and the master brake cylinder pressure present in the master brake cylinder 12 caused by the operation of the at least one piston pump 18 can at least temporarily push the at least one circuit pressure control valve 16 against the closing force to at least a partially open state. This can also be expressed as the pressure difference between the respective brake circuit pressure and the master brake cylinder pressure generating a counter force resisting the closing force, which counter force can / is able to move the at least one circuit pressure control valve 16 to at least a partially open state for at least a short time, despite the closing force being non-zero. Thus, during the return time interval, brake fluid can / is transferred to the master brake cylinder 12 via at least one circuit pressure control valve 16 which is pressed briefly several times to at least partially open state, despite the at least one circuit pressure control valve 16 being actuated by at least one valve control signal 16s.

[0023] On the other hand, the operation of the at least one circuit pressure control valve 16, effected by the at least one valve control signal 16s, can prevent the generation and propagation of noises that may be negatively perceived by the driver, despite the operation of the at least one piston pump 18. In particular, the pressure pulsations of the at least one piston pump 18, which in the past often emit undesirable noises during operation, can be damped by the operation of the at least one circuit pressure control valve 16. Thus, when using the control device 10 described herein, the master brake cylinder pressure itself can be increased to a relatively high pressure value, which is not associated with noises that may be negatively perceived by the driver. Even during low-speed driving with almost unmasked vehicle noises of a vehicle equipped with the control device 10, possibly without an internal combustion engine, the driver is not / is hardly annoyed by the noises of the brake system of his vehicle. When using the control device 10, among other things, knocking sounds, which in the past often occur when returning brake fluid from the at least one reservoir 22 to the master brake cylinder 12, are rare or impossible.

[0024] Instead of "fully closing" each circuit pressure control valve 16, at least one valve control signal 16s output by electronic device 10a only results in a "soft" closing of each circuit pressure control valve 16, such that the brake fluid flow triggered by at least one piston pump 18 pushes each circuit pressure control valve 16 briefly several times to an at least partially open state, thereby enabling an (almost) noiseless return of brake fluid from the at least one reservoir chamber 22 described above to the master brake cylinder 12.

[0025] The aforementioned advantages can also be provided by an alternative embodiment of the control device 10, in which the electronic device 10a of the control device 10 is designed and / or programmed such that during the return time interval at least one valve control signal 16s (each having a non-zero current intensity) can / is output by the electronic device 10a to at least one circuit pressure control valve 16 of the brake system, so that the at least one circuit pressure control valve 16 is closed at least temporarily during the return time interval based on the closing force provided, leaving a gap having a gap width of 10 μm (micrometers) to 100 μm (micrometers) and / or 1% to 10% of the maximum lift of the respective circuit pressure control valve 16. In this way, a "complete closure" of the respective circuit pressure control valve 16 can be avoided, thereby allowing return of brake fluid from the at least one reservoir 22 to the master brake cylinder 12, while at the same time no / almost no noise that may be felt by the driver is generated based on an "incomplete closure" of the respective circuit pressure control valve 16 during the return.

[0026] It is noted here that the control device 10 / the electronic device 10a of the control device can provide the above-mentioned advantageous possibility of operating the at least one circuit pressure control valve 16 (substantially) independently of the valve type of the at least one circuit pressure control valve 16 of the brake system. The applicability of the control device 10 is therefore not limited to a specific valve type of the at least one circuit pressure control valve 16.

[0027] 1 with two wheel brake cylinders 24 per brake circuit 14, at least one wheel inlet valve 26 and / or at least one wheel outlet valve 28 per brake circuit 14, and / or a non-energized high-pressure switching valve 30 per brake circuit 14, which hydraulically couples the respective brake circuit 14 to the master brake cylinder 12, should also be understood as merely exemplary. As illustrated in FIG. 1, a brake system equipped with / cooperating with the control device 10 can have a brake actuating element 32, such as, for example, a brake pedal 32, mechanically coupled to the master brake cylinder 12. However, the control device 10 can also advantageously cooperate with a brake-by-wire brake system. The brake booster 34 arranged upstream of the master brake cylinder 12, the brake fluid reservoir 36 hydraulically connected to the master brake cylinder 12 via at least one compensation bore, and the pressure sensor 38 connected to the brake circuit 14 are likewise only optional components of the brake system of FIG. 1. It should also be explicitly mentioned here that the provision of at least one damping element 40, 42 and 44, such as a damper 40, a throttle 42 and / or a non-return valve 44, arranged downstream of the discharge side of at least one piston pump 18 of the brake system, can be omitted. Due to the (almost) noiseless return of the brake fluid from the at least one storage chamber 22 to the master brake cylinder 12, which is possible by means of an advantageous design / programming of the electronic device 10a, the damping elements 40, 42 and 44 of the brake system of FIG. 1 could be omitted without any problem. In particular, based on the advantageous design / programming of the electronic device 10a, the conventional need to use a relatively expensive damper type, such as a CDD damper 40, for at least one damper 40 is eliminated.

[0028] If the brake system equipped with / cooperating with the control device 10 is equipped with at least one de-energized closed high pressure switching valve 30, the electronic device 10a can additionally be designed and / or programmed in an advantageous development such that during the return time interval, the energization of the at least one high pressure switching valve 30 of the brake system is prevented by the electronic device 10a, so that during the return time interval, the at least one high pressure switching valve 30 can / is switched to and / or can / is maintained in a closed state, respectively. In this way, during the (almost) noiseless return of brake fluid from the at least one reservoir 22 to the master brake cylinder 12, an undesirable transfer of brake fluid via the at least one high pressure switching valve 30 to the brake circuit 14, respectively coupled to this high pressure switching valve, can be prevented. This accelerates the desired brake pressure build-up in the master brake cylinder 12.

[0029] In particular, the at least one pump motor 20 is / is energized by the at least one pump control signal 20s during the entire duration of the return time interval. Preferably, the current strength of the at least one valve control signal 16s output to the at least one circuit pressure control valve 16 is also non-zero during the entire duration of the return time interval. For example, the electronic device 10a may be designed and / or programmed such that the current strength of each of the at least one valve control signal 16s output to the at least one circuit pressure control valve 16 is between 100 mA (milliamps) and 400 mA (milliamps) during the (entire) return time interval.

[0030] Advantageously, the design / programming of the electronic device 10a allows the current intensity of each of the at least one valve control signals 16s during the (full) return time interval to be set in such a way that the closing force of the at least one circuit pressure control valve 16 provided by the at least one valve control signal 16s can withstand a pressure difference of 3 bar between the brake circuit pressure present in the brake circuit 14 coupled via the respective circuit pressure isolation valve and the master brake cylinder pressure present in the master brake cylinder 12, but can be overcome by a pressure difference of 25 bar between the respective brake circuit pressure and the master brake cylinder pressure. In particular, the closing force of the at least one circuit pressure control valve 16 provided during the (full) return time interval can withstand a pressure difference of 10 bar between the brake circuit pressure present in the brake circuit 14 coupled via the respective circuit pressure isolation valve 16 and the master brake cylinder pressure, but can be overcome by a pressure difference of 25 bar, for example by a pressure difference of 20 bar, in particular by a pressure difference of 15 bar, between the respective brake circuit pressure and the master brake cylinder pressure. If desired, the closing force of the at least one circuit pressure control valve 16 provided during the (full) return time interval can also withstand a pressure difference of 3 bar between the brake circuit pressure present in the brake circuit 14 connected via the respective circuit pressure separation valve 16 and the master brake cylinder pressure, but can already be / be overcome by a pressure difference of 15 bar, in particular a pressure difference of 10 bar, between the brake circuit pressure present in the brake circuit 14 connected via the respective circuit pressure separation valve 16. It is also possible to set by the design / programming of the electronic device 10a such that the closing force of the at least one circuit pressure control valve 16 provided during the (full) return time interval can withstand a pressure difference of 15 bar, in particular a pressure difference of 20 bar, between the brake circuit pressure present in the brake circuit 14 connected via the respective circuit pressure separation valve 16 and the master brake cylinder pressure, but can be / be overcome by a pressure difference of 25 bar.

[0031] Likewise, the electronic device 10a can be designed and / or programmed in such a way that during the (total) return time interval the current strength of each of the at least one valve control signal 16s is equal to or less than one third, in particular equal to or less than one fourth, in particular equal to or less than one fifth of the maximum current strength which can be maximally delivered by the electronic device 10a to the at least one circuit pressure control valve 16. In this way, instead of a "full closure" of the at least one circuit pressure control valve 16, it is possible to bring about only a "soft" closure of the at least one circuit pressure control valve 16, whereby during the return time interval the at least one circuit pressure control valve 16 is briefly pushed several times to an at least partially open state by the brake fluid flow triggered by the at least one piston pump 18.

[0032] As a further advantageous development, the control device 10 / the electronic device 10a of the control device can also be designed / programmed to carry out the method steps of the return method described below.

[0033] FIG. 2 shows a flowchart for explaining an embodiment of a return method for a vehicle brake system.

[0034] The return method described below can be implemented in many different brake system types, the possibility of implementing the return method is not limited to a specific vehicle type / automobile type of the vehicle / automobile equipped with the respective brake system.

[0035] The method described herein may be preceded by an optional method step S0, in which at least one valve of the brake system, for example at least one wheel outlet valve of the brake system, is brought into and / or maintained at least partially open, so that brake fluid expelled from the master brake cylinder of the brake system is transferred to at least one reservoir of the brake system. Method step S0 may be performed, for example, to limit the brake pressure build-up in at least one wheel brake cylinder of the brake system to the response pressure in at least one reservoir, despite the operation of a brake operating element mechanically coupled to the master brake cylinder. In this way, the prevented braking action of the at least one wheel brake cylinder can be utilized for the generating mode of at least one electric motor of the vehicle, whereby the kinetic energy of the vehicle can be converted into storable electric energy without overbraking of the vehicle due to the generator braking torque provided by the generating mode of the at least one electric motor. However, the generator braking torque that can be provided at a maximum by the generating mode of the at least one electric motor is significantly reduced below a certain vehicle speed, as a result of which the wheel brake cylinders of the brake system are also required to bring the vehicle to a stop. By means of the return method described below, the brake fluid previously transferred to at least one reservoir of the brake system can be at least partially returned to the master brake cylinder, whereby a brake pressure boost is also triggered in at least one of the wheel brake cylinders by the response pressure in the at least one reservoir.

[0036] The return method comprises at least method steps S1 and S2 which are carried out together during a so-called return time interval, which can be understood as a time interval during which the desired return of brake fluid from at least one reservoir of a brake system to the master brake cylinder of this system is effected.

[0037] In method step S1 of the return method, at least one pump control signal is output to at least one pump motor of at least one piston pump of at least one brake circuit of the brake system equipped with at least one reservoir chamber, whereby brake fluid is transported from the at least one reservoir chamber based on the operation of the at least one piston pump caused by the respective pump control signal.

[0038] In method step S2 of the first embodiment of the return method, at least one valve control signal is output to at least one constantly controllable, de-energized open circuit pressure control valve of the brake system hydraulically coupling at least one brake circuit having at least one piston pump to a master brake cylinder. By at least one valve control signal it is understood that each of the valve control signals has a non-zero current intensity, such that the at least one circuit pressure control valve is respectively brought into and / or maintained in a closed state on the basis of a closing force provided by the respective valve control signal at least temporarily during the return time interval.

[0039] In a first embodiment, the respective current strength of the at least one valve control signal is / is set in such a way that during the return time interval the applied closing force of the at least one circuit pressure control valve is / is briefly overcome by the triggered action of the at least one piston pump, thus ensuring / ensuring that during the return time interval brake fluid is / is transported to the master brake cylinder via the at least one circuit pressure control valve which has been briefly pressed several times to an at least partially open state.

[0040] Alternatively to the first embodiment, a second embodiment of the return method can also be performed, in which in method step S2 at least one valve control signal (each with a non-zero current intensity) is output to at least one circuit pressure control valve of the brake system during the return time interval, whereby the at least one circuit pressure control valve is at least temporarily closed during the return time interval based on the applied closing force, leaving a gap with a gap width of 10 μm (micrometers) to 100 μm (micrometers) and / or 1% to 10% of the maximum lift of the respective circuit pressure control valve. In particular, at least one circuit pressure control valve can be closed leaving a gap width of 25 μm (micrometers) to 100 μm (micrometers), 10 μm (micrometers) to 75 μm (micrometers), 25 μm (micrometers) to 75 μm (micrometers), 2.5% to 10% of its maximum lift, 1% to 7.5% of its maximum lift, and / or 2.5% to 7.5% of its maximum lift.

[0041] Thus, carrying out method steps S1 and S2 together results in damping of pressure pulsations of the at least one piston pump by the at least one circuit pressure control valve actuated by the at least one valve control signal and a desired return of brake fluid from the at least one reservoir to the master brake cylinder based on a relatively "weak" closing force of the at least one circuit pressure control valve. It is expressly mentioned that the return method described herein can even result in a relatively high target master brake cylinder pressure without undesirable noise occurring during the return time interval.

[0042] The return method can also optionally include a method step S3 in which at least one de-energized high pressure switching valve of the brake system, which additionally hydraulically couples at least one brake circuit to the master brake cylinder, is respectively switched and / or maintained in a closed state during the return time interval, by not energizing and / or blocking the energization of the at least one high pressure switching valve during the return time interval. [Explanation of symbols]

[0043] 10 Control device 10a Electronic Devices 12 Master brake cylinder 14 Brake circuit 16 Circuit pressure control valve, circuit pressure isolation valve 16s Valve control signal 18 Piston pump 20 Pump motor 20s Pump control signal 22 Storage chamber 30 High pressure switching valve

Claims

1. 1. A control device (10) for a brake system of a vehicle, comprising an electronic device (10a) designed and / or programmed to output, during a return time interval, at least one pump control signal (20s) by said electronic device (10a) to at least one pump motor (20) of at least one piston pump (18) of at least one brake circuit (14) of the brake system, whereby brake fluid can be transported from at least one reservoir (22) of said at least one brake circuit (14) based on an induced operation of said at least one piston pump (18), the electronic device (10a) is additionally designed and / or programmed such that during the return time interval, at least one valve control signal (16s), each having a non-zero current intensity, can be output by the electronic device (10a) to at least one constantly controllable and normally open circuit pressure control valve (16) of the brake system hydraulically coupling the at least one brake circuit (14) to a master brake cylinder (12) of the brake system, whereby the at least one circuit pressure control valve (16) can be at least temporarily brought into and / or maintained in a closed state during the return time interval, respectively, based on an applied closing force, and wherein during the return time interval, the respective current strengths of the at least one valve control signal (16s) are set such that the induced operation of the at least one piston pump (18) can briefly overcome the applied closing force of the at least one circuit pressure control valve (16), thereby allowing brake fluid to be transported to the master brake cylinder (12) via the at least one circuit pressure control valve (16) that has been briefly pressed to an at least partially open state several times during the return time interval.

2. 2. The control device (10) according to claim 1, wherein the electronic device (10a) is designed and / or programmed such that the respective current strength of the at least one valve control signal (16s) during the return time interval is set such that the provided closing force of the at least one circuit pressure control valve (16) can withstand a pressure difference of 3 bar between the brake circuit pressure present in the brake circuit (14) coupled via the respective circuit pressure isolation valve (16) and the master brake cylinder pressure present in the master brake cylinder (12) and can be overcome by a pressure difference of 25 bar between the respective brake circuit pressure and the master brake cylinder pressure.

3. 3. The control device (10) according to claim 2, wherein the electronic device (10a) is designed and / or programmed such that the current intensity of each of the at least one valve control signals (16s) during the return time interval is set such that the applied closing force of the at least one circuit pressure control valve (16) can withstand a pressure difference of 10 bar between the brake circuit pressure and the master brake cylinder pressure present in the brake circuit (14) coupled via the respective circuit pressure isolation valve (16) and can be overcome by a pressure difference of 25 bar between the respective brake circuit pressure and the master brake cylinder pressure.

4. The electronic device (10a) comprises:

4. The control device (10) according to claim 2 or 3, designed and / or programmed such that the respective current strength of the at least one valve control signal (16s) is set during the return time interval such that the applied closing force of the at least one circuit pressure control valve (16) can withstand the pressure difference of 3 bar between the brake circuit pressure present in the brake circuit (14) coupled via the respective circuit pressure isolation valve (16) and the master brake cylinder pressure and can be overcome by a pressure difference of 15 bar between the respective brake circuit pressure and the master brake cylinder pressure.

5. 1. A control device (10) for a brake system of a vehicle, comprising an electronic device (10a) designed and / or programmed to output, during a return time interval, at least one pump control signal (20s) by said electronic device (10a) to at least one pump motor (20) of at least one piston pump (18) of at least one brake circuit (14) of the brake system, whereby brake fluid can be transported from at least one reservoir (22) of said at least one brake circuit (14) based on an induced operation of said at least one piston pump (18), 13. The control device according to claim 12, wherein the electronic device (10a) is capable of outputting, during the return time interval, at least one valve control signal (16s), each having a non-zero current intensity, to at least one constantly controllable and normally open circuit pressure control valve (16) of the brake system hydraulically coupling the at least one brake circuit (14) to a master brake cylinder (12) of the brake system, whereby the at least one circuit pressure control valve (16) is at least temporarily closed during the return time interval based on the applied closing force, leaving a gap having a gap width of 10 μm to 100 μm and / or 1% to 10% of the maximum lift of the respective circuit pressure control valve (16).

6. 6. The control device (10) of claim 1, wherein the electronic device (10a) is designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal (16s) is less than or equal to one-third of a maximum current strength that can be maximally output by the electronic device (10a) to the at least one circuit pressure control valve (16).

7. 7. The control device (10) of claim 6, wherein the electronic device (10a) is designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal (16s) is less than or equal to one-quarter of a maximum current strength maximally outputtable by the electronic device (10a) to the at least one circuit pressure control valve (16).

8. 8. The control device (10) of claim 7, wherein the electronic device (10a) is designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal (16s) is less than or equal to one-fifth of a maximum current strength maximally outputtable by the electronic device (10a) to the at least one circuit pressure control valve (16).

9. The control device (10) according to any one of claims 1 to 8, wherein the electronic device (10a) is designed and / or programmed such that during the return time interval, the current strength of each of the at least one valve control signal (16s) is between 100 mA and 400 mA.

10. 10. The control device (10) according to claim 1, wherein the electronic device (10a) is additionally designed and / or programmed such that during the return time interval, energization of at least one de-energized closed high pressure switching valve (30) of the brake system, which additionally hydraulically couples the at least one brake circuit (14) to the master brake cylinder (12), is prevented by the electronic device (10a), thereby making it possible to transition and / or maintain each of the at least one high pressure switching valves (30) in a closed state during the return time interval.

11. A control device (10) according to any one of claims 1 to 10, a brake circuit (14) hydraulically coupled to a master brake cylinder (12) of the brake system, the brake circuit having at least one normally controllable and de-energized open circuit pressure control valve (16), each controllable by the at least one valve control signal (16s) of the electronic device (10a) of the control device (10), the at least one piston pump (18) including the at least one pump motor (20), each controllable by the at least one pump control signal (20s) of the electronic device (10a), and the at least one reservoir chamber (22).

12. 1. A method for returning fluid for a brake system of a vehicle, comprising the step (S1) of outputting at least one pump control signal (20s) to at least one pump motor (20) of at least one piston pump (18) of at least one brake circuit (14) of the brake system during a return time interval, whereby brake fluid is transported from at least one reservoir (22) of the at least one brake circuit (14) based on the induced operation of the at least one piston pump (18), outputting at least one valve control signal (16s) having a non-zero current intensity during the return time interval to at least one constantly controllable and normally open circuit pressure control valve (16) of the brake system hydraulically coupling the at least one brake circuit (14) to a master brake cylinder (12) of the brake system, whereby the at least one circuit pressure control valve (16) is at least temporarily brought into and / or maintained in a closed state during the return time interval based on the applied closing force, and (S2) setting the current strength of each of the at least one valve control signals (16s) such that during the return time interval, the induced operation of the at least one piston pump (18) briefly overcomes the applied closing force of the at least one circuit pressure control valve (16), thereby transferring brake fluid to the master brake cylinder (12) via the at least one circuit pressure control valve (16) that has been briefly pressed to an at least partially open state several times during the return time interval.

13. 1. A method for returning fluid for a brake system of a vehicle, comprising the step (S1) of outputting at least one pump control signal (20s) to at least one pump motor (20) of at least one piston pump (18) of at least one brake circuit (14) of the brake system during a return time interval, whereby brake fluid is transported from at least one reservoir (22) of the at least one brake circuit (14) based on the induced operation of the at least one piston pump (18), outputting at least one valve control signal (16s), each having a non-zero current intensity, during the return time interval to at least one constantly controllable and de-energized open circuit pressure control valve (16) of the brake system hydraulically coupling the at least one brake circuit (14) to a master brake cylinder (12) of the brake system, whereby the at least one circuit pressure control valve (16) is at least temporarily closed during the return time interval based on the applied closing force, each leaving a gap having a gap width of 10 μm to 100 μm and / or 1% to 10% of a maximum lift of the respective circuit pressure control valve (16).

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