EP3509921A1

EP3509921A1 - Control device and method for increasing at least a brake pressure in at least one wheel-brake cylinder of a brake system of a vehicle

Info

Publication number: EP3509921A1
Application number: EP17739257.8A
Authority: EP
Inventors: Dirk Foerch
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-09-07
Filing date: 2017-07-12
Publication date: 2019-07-17
Also published as: US20200223415A1; KR20190045272A; CN109641581A; US11208087B2; DE102016216973A1; CN109641581B; WO2018046168A1; KR102368999B1

Abstract

The invention relates to a control device (10) for a brake system of a vehicle with an electronics system (12), which is designed to operate a motor-driven piston-cylinder device (14) in a pressure build-up mode, and at the same time, to control or maintain at least one first separating valve (26), by means of which at least one wheel-brake cylinder (28) is connected to a main brake cylinder (30), in the closed state thereof, and at least one second separating valve (32), by means of which the at least one wheel-brake cylinder (28) is connected to the motor-driven piston-cylinder device (14), in the open state thereof, and to operate the motor-driven piston-cylinder device (14) in a spy mode and simultaneously control the at least one second separating valve (32) in the closed state thereof, the electronics system (12) also being designed to control the at least one first separating valve (26) at least temporarily, in the open state thereof, during the spy mode. The invention also relates to a method for increasing at least a brake pressure in at least one wheel-brake cylinder (28) of a brake system of a vehicle.

Description

description

title

Control device and method for increasing at least one brake pressure in at least one wheel brake cylinder of a brake system of a vehicle

The invention relates to a control device for a brake system of

Vehicle and a braking system for a vehicle. Likewise, the invention relates to a method for increasing at least one brake pressure in at least one wheel brake cylinder of a brake system of a vehicle. Furthermore, the invention relates to a method for operating a brake system of a

Vehicle.

State of the art

In DE 10 2014 222 759 AI is a brake system for a vehicle

described, which is equipped with a motorized piston-cylinder device in addition to a master cylinder of the brake system. Each wheel brake cylinder of the brake system is connected via an associated first isolation valve to the master cylinder and via an associated second isolation valve to the motorized piston-cylinder device. By means of an operation of the motorized piston-cylinder device, in the closed presence of the first isolation valves and in the presence of the second isolation valves, brake fluid from the motorized piston-cylinder device should be transferable into the wheel brake cylinders, whereby at least one brake pressure can be increased in the wheel brake cylinders should. In addition, brake fluid from a brake fluid reservoir of the brake system in the motorized piston-cylinder device should be nachschnüffelbar.

Disclosure of the invention The invention provides a control device for a brake system of

A vehicle with the features of claim 1, a braking system for a vehicle having the features of claim 7, a method for increasing at least one brake pressure in at least one wheel brake cylinder of a

A braking system of a vehicle having the features of claim 8 and a method of operating a brake system of a vehicle with the

Features of claim 11. Advantages of the invention

By means of the present invention it is possible to set a recharge duration, i. a time duration, which requires a Nachschnüffeln brake fluid from the brake fluid reservoir in the tailed motorized piston-cylinder device to be bridged by the at least one open first isolation valve brake fluid is transferred from the master cylinder in the at least one attached thereto wheel brake cylinder. Thus, the present in the at least one wheel brake cylinder

Brake pressure can be increased despite the simultaneous executed Nachschnüffelns. The time duration of Nachschnüffelns / recharge time thus has no / hardly any influence on a time required for reaching at least one desired brake pressure in the at least one wheel brake cylinder. Accordingly, the duration of the Nachschnüffelns / recharge has no / hardly any effect on a braking distance at which the respective vehicle is braked / brought to a standstill due to a brake pressure build-up in the at least one wheel brake cylinder.

In an advantageous embodiment of the control device is the

Electronic device designed to at least temporarily control the at least one first isolation valve during the Nachschnüffelmodus at least temporarily in its open state, provided that a pressure in the master cylinder is above at least one brake pressure in the at least one wheel brake cylinder. The control device thus utilizes specific situations in which a driver brakes by means of an actuation of a brake actuating element / brake pedal in the master cylinder, and thereby a for transferring Brake fluid from the master cylinder in the at least one

Wheel brake cylinder sufficient pressure (or a sufficient volume) provides. The embodiment of the described here

Control device thus creates a possibility for the driver

Brake pressure increase in the at least one wheel brake cylinder at

Snoop / reload by means of his operation of the

Support brake actuator.

Preferably, the electronic device is additionally designed, after the Nachschnüffelmodus the at least one first isolation valve in his

To control or keep closed state to control the at least one second isolation valve in its open state and continue to operate the motorized piston-cylinder device in the pressure build-up mode. After a brief interruption of the pressure build-up mode for sucking sufficient brake fluid from the brake fluid reservoir into the motorized piston-cylinder device by means of the snoop mode, the pressure build-up mode can thus be continued.

As an advantageous development, the electronic device can additionally be designed to, during further operation of the motorized piston-cylinder device in the pressure build-up mode, the at least one first isolation valve for a predetermined, fixed or waiting time interval, which during the Nachschnüffelmodus from the master cylinder in the at least transferred a wheel brake cylinder

Brake fluid volume equals to control in its open state. Alternatively, the electronic device may also be designed, after the Nachschnüffelmodus the at least one during the Nachschnüffelmodus at least temporarily opened first isolation valve delayed by a predetermined, fixed or waited delay time, which corresponds to the transferred during the Nachschnüffelmodus from the master cylinder in the at least one wheel brake cylinder volume of brake fluid, to control in its closed state. By means of the temporary opening of the at least one first separating valve or the delayed closing of the at least one first separating valve, a volume compensation can be carried out, so that (despite the transfer of brake fluid from the Master cylinder in the at least one wheel brake cylinder during the Nachschnüffelmodus) a standard brake fluid quantity and a pressure (corresponding to a driver brake force and a predetermined

Driver braking force / pressure relation) is present in the master cylinder.

In a further advantageous embodiment of the control device, the electronic device is designed to operate by means of the operation of the motorized piston-cylinder device in the pressure build-up mode

Anti-lock control in the at least one wheel brake cylinder perform. Often, comparatively long anti-skid controls must be performed during vehicle deceleration / deceleration in which building / rebuilding of at least one desired brake pressure by the motorized piston-cylinder device for snooping must be stopped to bring the motorized piston-cylinder device back with it Fill brake fluid. In the embodiment of the control device described here, however, it is ensured that also during the

Nachschnüffelns building / rebuild the at least one desired brake pressure by opening the at least one first isolation valve is continued.

The advantages described above also provide a braking system for a vehicle with a corresponding control device, the master cylinder, the brake fluid reservoir, the at least one wheel brake cylinder, the motorized piston-cylinder device, the at least one first

Separating valve, via which the at least one wheel brake cylinder is connected to the master cylinder, and the at least one second

Isolating valve, via which the at least one wheel brake cylinder is connected to the motorized piston-cylinder device.

Also, carrying out a corresponding method for increasing at least one brake pressure in at least one wheel brake cylinder of a brake system of a vehicle effects the advantages described above. It should be noted that the method for increasing at least one brake pressure in at least one wheel brake cylinder of a brake system Vehicle according to the above-described embodiments of

Control device can be further developed.

Furthermore, a corresponding method of operating a brake system of a vehicle also provides the advantages described above. Also, the method for operating a brake system of a vehicle according to the above-described embodiments of the control device

weiterbildbar.

Brief description of the drawings

Further features and advantages of the present invention will be explained below with reference to the figures. Show it:

1 is a schematic representation of the control device, or

the brake system equipped therewith;

2 is a flowchart for explaining an embodiment of the method for increasing at least one

Brake pressure in at least one wheel brake cylinder of a brake system of a vehicle; and

3 is a flowchart for explaining an embodiment of the method for operating a brake system of a vehicle.

Embodiments of the invention

Fig. 1 shows a schematic representation of the control device, or of the brake system equipped therewith.

The control device 10 shown schematically by means of FIG. 1 can be used in a brake system of a vehicle / motor vehicle. It is expressly stated that the usability of the

Control device 10 neither on a particular type of brake system or on a specific type of vehicle / type of vehicle is limited. The braking system shown schematically in Fig. 1 is merely exemplary as a

hydraulic "one-box braking system" formed.

The control device 10 has an electronic device 12, which is designed to operate a motorized piston-cylinder device 14 of the braking system equipped with the control device 10 (by means of at least one first control signal 16a) in a pressure build-up mode. For this purpose, an engine 18 of the motorized piston-cylinder device 14 is controllable by means of the at least one first control signal 16a (in the pressure build-up mode) such that by means of an operation of the engine 18 at least one piston 20 of the motorized piston-cylinder device 14 in a Einbremsrichtung 22 adjustable is1 is adjusted. By means of the at least one displaced in the Einbremsrichtung 22 piston 20 is / is brake fluid from at least one storage volume 24 of the motorized piston-cylinder device 14 herausdrückbar / pushed out. In addition, the electronic device 12 is adapted, during the pressure build-up mode (or the operation of the motorized piston-cylinder device 14 in the pressure build-up mode) at least a first isolation valve 26, via which at least one wheel brake cylinder 28 of the brake system is connected to a master cylinder 30 of the brake system , (by means of at least one second control signal 16b) in his

to control or hold closed state. The electronic device 12 can thus ensure that during operation of the motorized piston-cylinder device 14 in the pressure build-up mode, the at least one

Wheel brake cylinder 28 is decoupled from the master cylinder 30 is / remains. Furthermore, the electronic device 12 is configured to control or to open at least one second isolation valve 32, via which the at least one wheel brake cylinder 28 is connected to the motorized piston-cylinder device 14 (by means of at least one third control signal 16c) hold. The electronic device 12 thus also ensures that the brake fluid forced out of the at least one storage volume 24 of the motorized piston-cylinder device 14 is displaced into the at least one wheel brake cylinder 28 via the at least one opened second isolation valve 32. By means of the operation of the motorized piston-cylinder Device 14 in the pressure buildup mode, therefore, at least one brake pressure in the at least one wheel brake cylinder 28 can be increased.

Often, the case occurs during operation of the motorized piston-and-cylinder device 14 in the pressure build-up mode to increase the at least one brake pressure in the at least one wheel brake cylinder 28 from the at least one storage volume 24 (currently) squeezable brake fluid volume consumed or less than one given

Minimum volume is / will. However, if this case occurs, then that is

Electronic device 12 adapted to the motorized piston-cylinder

Device 14 (by means of the at least one first control signal 16a) to operate in a Nachschnüffelmodus. In the Nachschnüffelmodus the motor 18 is controlled (by means of the at least one first control signal 16a) so that the at least one piston 20 in a (the braking direction 22 oppositely directed) opposite direction 34 is adjustable is1 adjusted. By means of the at least one displaced in the opposite direction 34 piston 20 is / brake fluid from a brake fluid reservoir 36 of the brake system in the at least one storage volume 24 is sucked / sucked. In addition, the

Electronic device 12 adapted to during the Nachschnüffelmodus (or the operation of the motorized piston-cylinder device 14 in the

Snoop mode) to control the at least one second isolation valve 32 (by means of the at least one third control signal 16c) to its closed state. During a Nachschnüffelns / suction of brake fluid from the brake fluid reservoir 36 in the at least one storage volume 24 is thus at least one wheel brake cylinder 28 of the motorized

Piston-cylinder device 14 decoupled before.

In addition, the electronic device 12 is also designed to control the at least one first isolation valve 26 (by means of the at least one second control signal 16b) at least temporarily into its open state during the snoop mode (ie, the operation of the piston-cylinder device 14 in the snoop mode) , Therefore, also during the

Nachschnüffelns brake fluid from the brake fluid reservoir 36 in the at least one storage volume 24, a brake fluid displacement from the master cylinder 30 via the at least one open first Separating valve 26 are carried out in the at least one wheel brake cylinder 28, whereby the at least one brake pressure in the at least one

Wheel brake cylinder 28 is steigerbar despite the simultaneous executed Nachschnüffelns. An interruption of a brake pressure increase in the

at least one wheel brake cylinder 28 must thus (for simultaneous

Snooping) can not be accepted. Likewise, no extension of a braking distance, in which the vehicle equipped with the control device 10 is brought to a standstill due to the increase in brake pressure in the at least one wheel brake cylinder 28, must be accepted for effecting the Nachschnüffelns.

Optionally, in one configuration of the respective brake system having at least two first isolation valves 26, only one of the at least two first isolation valves 26 of the operation of the motorized piston-cylinder device 14 in the Nachschnüffelmodus at least temporarily by means of the electronic device

12 be controllable in its open state. Alternatively, however, all of the at least two first isolation valves 26 during operation of the motorized piston-cylinder device 14 in the Nachschnüffelmodus at least temporarily be controlled by the electronic device 12 in its open state.

The electronic device 12 can recognize the case in which the brake fluid volume which can (currently) be pressed out of the at least one storage volume 24 is smaller or smaller than a predetermined minimum volume, for example because the electronic device 12 generates at least one sensor signal

38 of a sensor 40 and / or 42 of the motorized piston-cylinder device 14, such as a rotation rate sensor 40 and / or a

Motor current sensor 42, evaluates. As an alternative or as a supplement thereto, the electronic device 12 can also be designed to have at least one

Pressure signal 44 a to the at least one storage volume 24th

connected pressure sensor 46 to evaluate accordingly. However, the possibilities mentioned here, via which the electronic device 12 can recognize whether the brake fluid volume which can be pressed out of the at least one storage volume 24 (currently) is less than or smaller than the predetermined minimum volume, are to be interpreted only as an example. Advantageously, the electronic device 12 is adapted to operate by means of operating the motorized piston-cylinder device 14 in the

Pressure build-up mode, an anti-skid control in the at least one

Perform wheel brake cylinder 28. Frequently occurs especially during a

Execution of anti-skid control on the case that from the at least one storage volume 24 of the motorized piston-cylinder device 14 used (currently) herausdrückbare brake fluid volume is less than or a predetermined minimum volume, and therefore a Nachschnüffeln brake fluid from the brake fluid reservoir 36 is necessary , However, by means of the control device 10 described here, it is possible to ensure that one needed to perform the Nachschnüffelns

Duration / recharge time by means of the at least temporary opening of the at least one first isolation valve 26 can be bridged.

Preferably, the electronic device 12 is also configured to at least temporarily control the at least one first isolation valve 26 during its Nachschnüffelmodus (ie during operation of the motorized piston-cylinder device in the Nachschnüffelmodus) in its open state, if a pressure in the Master cylinder 30 is above the at least one brake pressure in the at least one wheel brake cylinder 28. The control device 10 can thus be targeted in situations in which a driver of the vehicle equipped with the control device 10 by means of an operation of a brake operating member / brake pedal 56 in the

Brake master cylinder 30 brakes, one for increasing the at least one

Brake pressure in the at least one wheel brake cylinder 28 sufficient volume (or a correspondingly high enough pressure) in the

Master brake cylinder 30 for the desired brake pressure increase (during operation of the motorized piston-cylinder device 14 in the

Snoop mode). Especially in the case of a driver

Emergency braking is often very strong on the brake actuator 56 suppressed, especially in such a situation no delayed

Brake pressure increase and no braking distance increase (despite the

in the meantime necessary Nachschnüffelns brake fluid from the brake fluid reservoir 36 in the at least one storage volume 24) in To be taken. The advantageous design of the electronic device 12 thus causes a fast, especially in such a situation

Slow down / slow down the vehicle. For example, the electronic device 12 may be configured to evaluate at least one pressure signal 48 of at least one pressure sensor 50 connected to the master cylinder 30 with respect to the (actual) pressure in the master cylinder 30. In addition, at least one (not sketched) sensor signal of a brake actuator element sensor 52 and / or 54, such as a rod travel sensor 52 and / or a

Differential path sensors 54, for estimating / calculating the pressure in the

Master cylinder 30 can be evaluated by means of the electronic device 12. The electronic device 12 may also be designed to estimate / calculate the at least one brake pressure in the at least one wheel brake cylinder 28. Alternatively, at least one (not outlined) pressure sensor in the

Brake system present by means of which the at least one brake pressure in the at least one wheel brake cylinder 28 is measurable. Furthermore, at least one value relative to the pressure in the master cylinder 30 and / or the at least one brake pressure in the at least

Wheel brake cylinder 28 via a (not shown) vehicle bus to the

Electronic device 12 are provided.

Of course, the electronic device 12 may additionally be configured, after the snoop mode (or the operation of the motorized piston-cylinder device 14 in the snoop mode), to have the at least one first one

Isolation valve 26 to control or hold in its closed state, to control the at least one second isolation valve 32 in its open state and to operate the motorized piston-cylinder device 14 in the pressure build-up mode. This is particularly advantageous, although after operation of the motorized piston-cylinder device 14 in the Nachschnüffelmodus

(and the possibly carried out transfer of brake fluid from the master cylinder via the at least one open first isolation valve 26 in the at least one wheel brake cylinder 28) at least one

predetermined / desired target brake pressure in the at least one

Wheel brake cylinder 28 is not yet established. After an interruption of the Pressure build-up mode for sniffing brake fluid from the

Brake fluid reservoir 36 in the at least one storage volume 24, the pressure build-up mode can be continued with it. In an advantageous further development, the electronic device 12 is additionally designed to control the at least one first isolation valve 26 into its open state during a further operation of the motorized piston-cylinder device 14 in the pressure build-up mode for a (fixed) predetermined, fixed or awaited time interval , The respective time interval for which the at least one first isolation valve 26 in its open

State is controlled, preferably corresponds to one during the

Nachschnüffelmodus from the master cylinder 30 in the at least one wheel brake cylinder 28 transferred brake fluid volume. For example, this can be transferred from the master brake cylinder 30 into the at least one wheel brake cylinder 28 during the snoop mode

Brake fluid volumes are calculated or estimated, and then set the time interval accordingly. Likewise, after a control of the at least one first isolation valve 26 in its open state, it can be waited until a brake fluid volume corresponding to the volume of brake fluid transferred into the at least one wheel brake cylinder 28 during the snoop mode is transferred back into the master brake cylinder 30 (or a corresponding brake fluid volume) Pressure in master cylinder 30) before the at least one first isolation valve 26 is controlled to its closed state. By means of the motor 18 of the motorized piston-cylinder device 14 can be applied

Engine power, the previously transferred from the master cylinder 30 in the at least one wheel brake cylinder 28 brake fluid volume (as a "lost" volume of the master cylinder 30) are usually easily pushed into the master cylinder 30. Therefore, in this

Further development of the control device 10, a volume compensation possible, which

(despite the transfer of the brake fluid volume from the

Master cylinder 30 via the at least one opened first isolation valve 26 in the at least one wheel brake cylinder 28 during the

Nachschnüffelmodus) ensures that in the master cylinder 30, a standard amount of brake fluid and the actuation of the Brake actuator 56 corresponding pressure present. Fluctuations in the amount of brake fluid and the pressure in the master cylinder 30 are thus so short that the driver operating the brake actuator 56 does not notice them. Another advantage of this embodiment of the control device 10 is that, if a Nachschnüffeln is carried out briefly after an already performed Nachschnüffeln, even during the subsequent Nachschnüffelns the at least one brake pressure in the at least one wheel brake cylinder 28 by at least temporarily opening the at least one first isolation valve 26 can be further increased. Although the amount of brake fluid in the master cylinder 30 is typically relatively small, the "renewable brake fluid quantity" in the

Master cylinder 30 are used to bridge a repeated Nachschnüffelns. Alternatively, the electronic device 12 may also be designed according to

Nachschnüffelmodus the at least one during the Nachschnüffelmodus at least temporarily opened first isolation valve 26 by a (fixed) predetermined, fixed or waiting delay time delayed in his

to control closed state. Preferably, the (fixed) predetermined, fixed or waiting delay time corresponds to that during the

Nachschnüffelmodus from the master cylinder 30 in the at least one wheel brake cylinder 28 transferred brake fluid volume. With regard to the possibilities for determining or waiting for the delay time, reference is made to the statements in the preceding paragraph.

The brake system shown schematically in Fig. 1, in addition to the brake system components described above, each have a wheel inlet valve 58 and one wheel outlet valve 60 per wheel brake cylinder 28. In addition, a simulator 62 via a Simulatortrennventil 64 and a parallel to the

Simulatortrennventil 64 arranged relief valve 66 at the

Master cylinder 30 connected. (Another pressure relief valve 68 connects the at least one storage volume 24 of the motorized piston-cylinder device 14 to the brake fluid reservoir 36.) Further, the master cylinder 30 is connected to the brake fluid reservoir 36 via a reservoir isolation valve 70 (having a check valve disposed parallel thereto) connected. However, it should be noted that equipment of the braking system with those described in this paragraph

Brake system components is only optional.

The above-described advantages of the control device 10 also causes a braking system equipped therewith for a vehicle with at least the

Master cylinder 30, the brake fluid reservoir 36, the at least one wheel brake cylinder 28, the motorized piston-cylinder device 14, the at least one first isolation valve 26, via which the at least one wheel brake cylinder 28 is connected to the master cylinder 30, and the at least one second isolation valve 32nd , via which the at least one wheel brake cylinder 28 is connected to the motorized piston-cylinder device 14.

FIG. 2 shows a flowchart for explaining an embodiment of the method for increasing at least one brake pressure in at least one wheel brake cylinder of a brake system of a vehicle.

The method described below can be carried out, for example, by means of the braking system explained above. It is, however, on it

pointed out that a feasibility of the method is not limited to the use of this type of brake system.

The method steps Sl to S3 are carried out (almost) simultaneously to a means of a motorized piston-cylinder device of the

Brake fluid in the at least one wheel brake cylinder to transfer. As a method step Sl, at least a first separating valve, via which the at least one wheel brake cylinder with a

Master cylinder of the brake system is connected, controlled or held in its closed state. As a method step S2, at least one second isolation valve, via which the at least one wheel brake cylinder is connected to the motorized piston-cylinder device, is controlled or held in its open state. Also, in one

Method step S3 at least one piston of the motorized piston-cylinder device so (in a Einbremsrichtung) process that brake fluid from at least one (bounded by the at least one piston)

Storage volume of the motorized piston-cylinder device is pressed out. The pushed-out brake fluid is transferred via the at least one opened second isolation valve in the at least one wheel brake cylinder.

If it is detected that a brake fluid volume which can be pressed out of the at least one storage volume (currently) is consumed or is smaller than a predetermined minimum volume, the method steps S4 to S6 are carried out in order to re-sniff brake fluid from one

Brake fluid reservoir of the brake system in the at least one

Memory volume to effect. This is done by means of a retraction of the at least one piston (in a direction opposite to the braking direction) as a method step S4. At the same time or almost simultaneously, as a method step S5, the at least one second step

Control valve controlled during Nachschnüffelns in its closed state. In addition, while snooping in a

Process step S6, the at least one first isolation valve at least temporarily controlled in its open state. Thus, also carrying out the method described herein causes the advantages explained above.

Preferably, the at least one first isolation valve (as process step S6) is at least temporarily controlled during its Nachschnüffelns in its open state, provided that a pressure in the master cylinder is above the at least one brake pressure in the at least one wheel brake cylinder. Possibilities for recognizing such a situation have already been described above.

After the Nachschnüffeln effected by means of the method steps S4 to S6, the method steps S1 to S3 can again be carried out, whereby the at least one first isolation valve is controlled or held in its closed state, the at least one second isolation valve is controlled in its open state, and the method the at least one piston (in the Einbremsrichtung) for pushing out brake fluid from the

at least one storage volume is continued. FIG. 3 shows a flowchart for explaining an embodiment of the method for operating a brake system of a vehicle. Also, the method described below for operating a

Braking system of a vehicle can by means of the previously explained

Braking system are running. It should be noted, however, that a feasibility of the method described below is not limited to the

Use of this type of brake system is limited.

In the method described here, while the method of the at least one piston (in the braking direction) is continued for expelling brake fluid from the at least one storage volume, a method step S7 is executed. In the method step S7, the at least one first isolation valve for a predetermined, fixed or waiting time interval, which during a Nachschnüffelns from the master cylinder into the at least one wheel brake cylinder

transferred brake fluid volume is controlled in its open state. Options for setting or waiting for the time interval are already described above.

Alternatively, after the snooping effected by means of the method steps S4 to S6, the method step S1 can be compared with FIG

Method steps S2 and S3 by a predetermined, fixed or waiting delay time, which corresponds to the transferred during the Nachschnüffelmodus from the master cylinder into the at least one wheel brake cylinder volume of the brake fluid, are executed delayed. In this case, the at least one during the Nachschnüffelns at least temporarily opened first isolation valve is delayed by the delay time controlled in its closed state.

The method steps S1 to S3 for increasing the at least one

Brake pressure in the at least one wheel brake cylinder can be performed for anti-skid control in the at least one wheel brake cylinder.

Claims

claims

A control device (10) for a braking system of a vehicle comprising: an electronic device (12) configured to:

- A motorized piston-cylinder device (14) of the brake system in one

To operate pressure build-up mode, in which at least one in a Einbremsrichtung (22) adjusted piston (20) of the motorized piston-cylinder device (14) brake fluid from at least one

Storage volume (24) of the motorized piston-cylinder device (14) can be pushed out; and

- During the pressure build-up mode at least a first isolation valve (26), via which at least one wheel brake cylinder (28) of the brake system is connected to a master cylinder (30) of the brake system, in its closed state and at least a second isolation valve (32) via which the at least a wheel brake cylinder (28) with the motorized

Piston-cylinder device (30) is connected to control or hold in its open state; wherein, if one of the at least one storage volume (24)

squeezable volume of brake fluid consumed or less than a predetermined minimum volume, the electronic device (12) is designed to:

- To operate the motorized piston-cylinder device (14) in a Nachschnüffelmodus, in which by means of at least one in an opposite direction (34) adjusted piston (20) brake fluid from a

Brake fluid reservoir (36) of the brake system in the at least one storage volume (24) is sucked; and

- to control the at least one second isolation valve (32) in its closed state during the Nachschnüffelmodus; characterized in that, the electronic device (12) is additionally designed during the

Nachschnüffelmodus the at least one first isolation valve (26) at least temporarily to control its open state.

2. Control device (10) according to claim 1, wherein the electronic device (12) is designed to at least temporarily control the at least one first isolation valve (26) during the Nachschnüffelmodus in its open state, provided that a pressure in the master cylinder (30 ) lies above at least one brake pressure in the at least one wheel brake cylinder (28).

3. Control device (10) according to claim 1 or 2, wherein the

Electronic device (12) is additionally designed according to

Snoop mode to control or hold the at least one first isolation valve (26) in its closed state, control the at least one second isolation valve (32) to its open state, and continue to operate the motorized piston-cylinder device (14) in the pressure build-up mode ,

4. Control device (10) according to claim 3, wherein the electronic device (12) is additionally designed, during further operation of the motorized piston-cylinder device (14) in the pressure build-up mode, the at least one first isolation valve (26) for a predetermined, fixed or waiting time interval, which one during the Nachschnüffelmodus from the

Master brake cylinder (30) in the at least one wheel brake cylinder (28) transferred brake fluid volume corresponds to control in its open state.

5. Control device (10) according to claim 3, wherein the electronic device (12) is additionally designed, after the Nachschnüffelmodus the at least one at least temporarily during the Nachschnüffelmodus at least temporarily opened first isolation valve (26) delayed by a predetermined, fixed or waited delay time, which during Nachschnüffelmodus from the master cylinder (30) in the at least one wheel brake cylinder (28) transferred brake fluid volume corresponds to control in its closed state.

6. Control device (10) according to one of the preceding claims, wherein the electronic device (12) is adapted to perform by means of operating the motorized piston-cylinder device (14) in the pressure build-up mode, an antiskid control in the at least one wheel brake cylinder (28).

7. A braking system for a vehicle comprising: the control device (10) according to any one of the preceding claims; the master cylinder (30); the brake fluid reservoir (36); the at least one wheel brake cylinder (28); the motorized piston-cylinder device (14); the at least one first isolation valve (26), via which the at least one wheel brake cylinder (28) is connected to the master brake cylinder (30); and the at least one second isolation valve (32), via which the at least one wheel brake cylinder (28) is connected to the motorized piston-cylinder device (14).

8. A method for increasing at least one brake pressure in at least one wheel brake cylinder (28) of a brake system of a vehicle comprising the steps of:

Controlling or holding at least a first isolation valve (26), via which the at least one wheel brake cylinder (28) is connected to a master brake cylinder (30) of the brake system, in its closed state (Sl); Controlling or holding at least one second isolation valve (32), via which the at least one wheel brake cylinder (28) is connected to a motorized piston-cylinder device (14) of the brake system, in its open state (S2);

Method of at least one piston (20) of the motorized piston-cylinder device (14) so that brake fluid from at least one

Storage volume (24) of the motorized piston-cylinder device (14) is pushed out (S3); and, if it is detected that a brake fluid volume which can be pressed out of the at least one storage volume (24) is consumed or less than a predetermined minimum volume, sniffing brake fluid from a brake fluid reservoir (36) of the brake system into the at least one storage volume (24) by means of a return movement of the brake fluid reservoir at least one

Piston (20) (S4), wherein the at least one second isolation valve (32) is controlled in its closed state during the Nachschnüffelns (S5); characterized in that during the Nachschnüffelns the at least one first isolation valve (26) is at least temporarily controlled in its open state (S6).

9. The method of claim 8, wherein the at least one first isolation valve (26) is at least temporarily controlled during the Nachschnüffelns in its open state, provided that a pressure in the master cylinder (30) above the at least one brake pressure in the at least one

Wheel brake cylinder (28) is located.

10. The method of claim 8 or 9, wherein after the Nachschnüffeln the at least one first isolation valve (26) is controlled or held in its closed state (Sl), the at least one second isolation valve (32) is controlled in its open state (S2) , and the process of the at least one piston (20) for forcing out brake fluid from the at least one storage volume (24) is continued (S3).

11. A method of operating a braking system of a vehicle comprising the step of:

Increasing at least one brake pressure in at least one wheel brake cylinder (28) of the brake system by means of the method according to one of claims 8 to 10.

12. The method of claim 10 and 11, wherein, while the method of at least one piston (20) for pushing out brake fluid from the at least one storage volume (24) is continued, the at least one first isolation valve (26) for a given, fixed or Waited time interval, which during a Nachschnüffelns from the

Master brake cylinder (30) in the at least one wheel brake cylinder (28) transferred brake fluid volume corresponds, is controlled in its open state (S7).

13. The method according to claim 10 and 11, wherein after the Nachschnüffeln the at least one during Nachschnüffelns at least temporarily opened first isolation valve (26) delayed by a predetermined, fixed or waited delay time, which during the Nachschnüffelmodus from the master cylinder (30) in the At least one wheel brake cylinder (28) corresponds to transferred brake fluid volume is controlled in its closed state.

14. The method according to any one of claims 11 to 13, wherein the increasing of the at least one brake pressure in the at least one wheel brake cylinder (28) according to claim 1 or 2 for anti-skid control in the at least one wheel brake cylinder (28) is executed.