Method for operating a brake system upon detection of a leak, and control device for carrying out such a method

Abstract

The present invention relates to a method for operating a brake system upon detection of a leak, the brake system comprising a pressure source (2) connected via a pressure supply valve (5) to a first brake control circuit (6a) and additionally via a brake circuit shut-off valve (4) to a second brake control circuit (6b), the pressure source (2) supplying pressurized pressure medium from a first chamber (3a) of a pressure medium reservoir (3) to the brake control circuits (6a, 6b), each brake control circuit (6a, 6b) being connected to the second chamber (3b) via a common outlet connecting line (13). In order to continue operating the brake system (1) using only the first brake control circuit (6a) when a leak occurs in the second brake control circuit (6b), a valve that allows a connection to be established between the second chamber (3b) of the pressure medium reservoir (3) and the pressure source (2) via the pressure medium pump (10) is opened and the pressure medium pump (10) is activated. The brake circuit shut-off valve (4) is then closed and the first brake control circuit (6a) is operated by the pressure source (2). When the brake system (1) is switched to an idle state, the pressure source (2) is first activated to send pressure medium from the pressure source (2) into the second chamber (3b) of the pressure medium reservoir (3).

Description

[Technical Field]

[0001] The invention relates to a method for operating a brake system upon detection of a leak, formed by an electrically operated pressure source connected to a first brake control circuit via a first pressure line and a pressure supply valve and to a second brake control circuit via the pressure supply valve and additionally via a brake circuit shut-off valve, the electrically operated pressure source supplying pressurized pressure medium from a first chamber of a pressure medium reservoir to the brake control circuits, each brake control circuit having a respective inlet valve, each brake control circuit being connected to a pressure source via its respective inlet valve and each brake control circuit having a respective outlet valve, each brake control circuit being connected to the pressure source via its respective outlet valve, all outlet valves being connected to the second chamber of the pressure medium reservoir via a common outlet connecting line, the pressure source being connected to the first chamber via a non-return valve, the common outlet connecting line being connected to the second brake control circuit via a pressure medium pump, the pressure source being connected to the first chamber of the pressure medium reservoir via the first valve.

[0002] The invention additionally relates to a control device for a braking system having a processor for carrying out such a method. [Background technology]

[0003] Hydraulic brake systems are susceptible to pressure medium leaks, which can affect connections in the piping system, valves, or actuators such as calipers or pumps. In the worst case, the entire brake system can become starved, resulting in the impossibility of test runs. In the case of motor vehicles, a fundamental requirement of the brake system is that the wheels or wheel brakes must be connected to a pressure medium reservoir in such a way that the pressure medium is contained in the system without pressure when the control unit is de-energized, i.e., when the brake system is in idle mode.

[0004] Particularly in the case of a wheel leak, a complete loss of brake fluid can occur very quickly in the sleep state, especially if valves that remain open when de-energized are used.

[0005] Modern brake systems often no longer have the traditional dual or multiple circuits. This means that the different wheel brakes can no longer be permanently separated into two separate pressure medium circuits, but instead only have an electrical dual circuit that only operates when the electronics are active. As a result, these systems are particularly vulnerable to wheel leakage during sleep.

[0006] The pressure medium reservoir may have several chambers that are partially separated from one another, so that in the event of a wheel leak, one chamber can be emptied while the supply of pressure medium into the other chamber still occurs. However, since the pressure medium circuit is connected during normal operation, the remaining pressure medium can be lost due to a leak, which can make further use of the brake system impossible. Summary of the Invention [Means for solving the problem]

[0007] It is therefore desirable to provide a method and a control device that allows the above-described braking system to be operated at least partially in a safe mode, so that the most necessary braking intervention is still possible, but no further pressure medium can be lost due to leakage.

[0008] A suitable method therefore provides that, in the case of the brake system described above, in the event of a leak in the second brake control circuit, for further operation of the brake system using only the first brake control circuit, the valve enabling connection of the second chamber of the pressure medium reservoir with the pressure source and / or the first chamber of the pressure medium reservoir via the pressure medium pump is opened, the pressure medium pump is activated so that pressure medium is pumped from the second chamber of the pressure medium reservoir into the pressure source and / or the first chamber of the pressure medium reservoir through the resulting connection, then the brake circuit shut-off valve is closed and the first brake control circuit is operated with pressure medium from the first chamber of the pressure medium reservoir by the pressure source.When the brake system is put into an idle state, firstly pressure medium is conveyed from the pressure source into the second chamber of the pressure medium reservoir by activating the pressure source.

[0009] The lockable brake circuit shut-off valve therefore allows only the first brake control circuit to be operated from the first chamber of the pressure medium reservoir by the associated pressure source during braking. In the idle state, brake fluid is reserved in the second chamber of the pressure medium reservoir. Advantageously, depending on the pumping direction, both the pressure source and the pressure medium pump are used for pumping in the forward and reverse directions.

[0010] In an advantageous configuration of the method, in a third step after pumping the pressure medium of the pressure source into the second chamber of the pressure medium reservoir, pressure medium is drawn from the first chamber of the pressure medium reservoir into the pressure source and then pumped into the second chamber of the pressure medium reservoir.

[0011] In this way, during the idle phase not only is pressure medium from the pressure source secured in the second chamber of the pressure medium reservoir, but also pressure medium from the first chamber of the pressure medium reservoir.

[0012] This can be done several times in succession until, in the event of a leak in the second brake control circuit, all of the pressure medium in the first chamber of the pressure medium reservoir is pumped into the second chamber of the pressure medium reservoir and secured there against leakage.

[0013] In an advantageous embodiment of the method, in the event of a leak in the second brake control circuit, the pressure supply valve and the brake circuit shut-off valve are opened and the pressure medium pump is activated in order to fill the pressure source with pressure medium from the second chamber of the pressure medium reservoir for further operation of the brake system using only the first brake control circuit.When the brake system is put into an idle state, first the first valve and the brake circuit shut-off valve are closed, and the at least one outlet valve and one inlet valve of the first brake control circuit and the pressure supply valve are opened, and the pressure source is operated to transport pressure medium from the pressure source into the second chamber of the pressure medium reservoir.

[0014] Thus, every re-pumping operation opens an available advantageous valve.

[0015] The object is also to provide a method for operating a brake system upon detection of a leak, formed by an electrically operated pressure source connected to a first brake control circuit via a first pressure line and a pressure supply valve and to a second brake control circuit via the pressure supply valve and additionally via a brake circuit shut-off valve, the electrically operated pressure source supplying pressurized pressure medium from a first chamber and / or a third chamber of a pressure medium reservoir to the brake control circuits, each brake control circuit having a respective inlet valve, each brake control circuit connected to the pressure source via the respective inlet valve, each brake control circuit having a respective outlet valve, each brake control circuit connected to the second chamber of the pressure medium reservoir via the respective outlet valve, all outlet valves being connected to the second chamber of the pressure medium reservoir via a common outlet connecting line, the pressure source being connected to the first chamber or the third chamber via a non-return valve, the common outlet connecting line being connected to the second brake control circuit via a pressure medium pump, the pressure source being connected to the first chamber of the pressure medium reservoir via the first valve, the method comprising the steps of: This can also be achieved by a method comprising the steps of: when a leak occurs in the second brake control circuit, a valve enabling connection between the second chamber of the pressure medium reservoir and the first pressure line via the pressure medium pump is opened, the pressure medium pump is operated so that pressure medium from the second chamber of the pressure medium reservoir is pumped into the first pressure line through the resulting connection, and then the brake circuit shut-off valve is closed and the first brake control circuit is operated by the pressure source using pressure medium from the first chamber of the pressure medium reservoir, for further operation of the brake system only with the first brake control circuit.

[0016] Since the pressure source cannot run out in the event of a wheel leak, it is sufficient to fill the first pressure line via the pressure medium pump for emergency driving operations.

[0017] This object is also achieved by a control device for a braking system, having a processor for carrying out one of the methods described above.

[0018] To this end, the processor is equipped to carry out such a method by executing appropriate computer instructions, which may be stored in a memory of the control device or otherwise external to the control device and read and executed by the processor.

[0019] The invention is explained in more detail below with reference to exemplary embodiments using figures. [Brief explanation of the drawings]

[0020] [Figure 1] 1 shows a schematic hydraulic circuit diagram of a brake system used for the method according to the invention; [Figure 2] 2 shows a diagram of front wheel leakage in the braking system according to FIG. 1. [Figure 3] 2 shows an example of a re-pumping operation in the braking system according to FIG. 1. [Figure 4] 2 shows an example of an opposite re-pumping action in the braking system according to FIG. 1; [Figure 5] 3 shows a further schematic hydraulic diagram of a brake system used for the method according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0021] 1 shows very diagrammatically an exemplary embodiment of a brake system 1 for a motor vehicle. According to the exemplary embodiment, the brake system 1 is designed to operate four hydraulically operated wheel brakes 7a, 7b, 7c and 7d. According to the exemplary embodiment, the wheel brakes 7a and 7b are assigned to the front axle, and the wheel brakes 7c and 7d are assigned to the rear axle of the motor vehicle. The wheel brakes 7a and 7b of the front axle are part of the second brake control circuit 6b, and the wheel brakes 7c and 7d of the rear axle are part of the first brake control circuit 6a.

[0022] The brake system 1 has a pressure medium reservoir 3 with two at least partially separated chambers, a first chamber 3a to which a first tank connection is assigned and a second chamber 3b to which a second tank connection is assigned.

[0023] In the brake system 1, the electrically actuated pressure source 2 and the wheel-specific brake pressure regulating valves are arranged as components of brake control circuits 6a, 6b, which are designed as electrically actuated inlet valves 8a, 8b, 8c, and 8d and electrically actuated outlet valves 9a, 9b, 9c, and 9d for each wheel brake 7a-7d. The outlet valves 9a, 9b, 9c, and 9d are connected to the second chamber 3b of the pressure medium reservoir 3 via a common outlet connection line 13.

[0024] On the pressure side, the pressure source 2 is connected via a first pressure line 14 and a pressure supply valve 5 to a second pressure line 15, to which the inlet valves 8c and 8d of the first brake control circuit 6a are connected. The wheel brakes 7c and 7d can therefore be directly actuated by the pressure source 2.

[0025] The pressure source 2 is additionally connected to the inlet valves 8a and 8b of the second brake control circuit 6b via the pressure supply valve 5, the fourth pressure line 16, the brake circuit shut-off valve 4 and the third pressure line 12. The wheel brakes 7a and 7b of the front axle can thus likewise be actuated directly by the pressure source 2. However, it is also possible to shut off the second brake control circuit 6b from the pressure source 2 by the brake circuit shut-off valve 4, for example if a leak is detected.

[0026] To prevent any possible loss of pressure medium in the event of, for example, a leak in a wheel brake, the pressure source 2 can be isolated from the brake control circuit 6a, 6b by the pressure supply valve 5, for example to confine the pressure medium within the pressure source 2. In addition, the pressure supply valve 5 can be closed so that, by retracting, the pressure source 2 can draw pressure medium from the first chamber 3a of the pressure medium reservoir 3 via the check valve.

[0027] At least one electronic control unit 20 is provided, which is shown highly diagrammatically in Figure 1. Each electronic control unit includes electrical and / or electronic elements (e.g., microcontrollers, power modules, valve drivers, other electronic components, etc.) for operating electrically actuated components of the brake system 1, and optionally associated sensors. For clarity, connection lines to such actuators and sensors have been omitted.

[0028] An electronic control unit 20 controls the pressure source 2. According to this example, the pressure source 2 is supplied with energy via the electronic control unit 20 (from an electrical energy source, not shown).

[0029] The electrically controlled pressure source 2 is, for example, in the form of a hydraulic cylinder-piston arrangement (or a single-circuit electrohydraulic actuator (linear actuator)), the piston of which can be actuated, in particular advanced and retracted, by an electric motor interposed by a rotation-translation mechanism in order to build up and dissipate pressure in a pressure chamber. The piston defines the pressure chamber of the pressure source 2. A rotor position sensor, shown only diagrammatically, which detects the rotor position of the electric motor, is provided for actuating the electric motor.

[0030] The pressure chamber is connected via a (refill) line to the pressure medium reservoir 3 or to its first chamber 3a, regardless of the operating state of the piston. A check valve is arranged in the line, which closes in the direction of the pressure medium reservoir 3. The cylinder-piston arrangement 2 may additionally have a compensation port (not shown). By retracting the piston, pressure medium can be drawn from the pressure medium reservoir 3 into the pressure chamber.

[0031] The brake system 1 comprises a pressure medium pump 10 which is additionally connected on the inlet side to the second chamber 3b of the pressure medium reservoir 3 via an outlet connecting line 13. On the output side, the pressure medium pump 10 is connected via a third pressure line 12 to the inlet valves 8a, 8b of the second brake control circuit 6b.

[0032] The pressure medium pump 10 is thus able to supply pressure medium to the second brake control circuit 6b and to operate the second brake control circuit 6b. The pressure medium pump 10 can likewise be supplied with energy and controlled by the control device 20, in particular to be switched on and off.

[0033] Since the brake circuit shut-off valve 4 is likewise connected to the first brake control circuit 6a via a fourth pressure line 16 and a second pressure line 15, the pressure medium pump 10 can also supply pressure medium to the first brake control circuit 6a via this brake circuit shut-off valve 4.

[0034] The electrically controlled pressure medium pump 10 is designed in the exemplary embodiment of FIG. 1 as a two-piston pump, the two pressure sides and the two suction sides of which are in each case connected to one another.

[0035] The pressure medium pump 10 has check valves on both its pressure side and its suction side, so that it can only convey pressure medium in the direction from the second chamber 3b of the pressure medium reservoir 3 to the brake control circuits 6a, 6b.

[0036] In the brake system 1 of Figure 1, the pressure source 2 is additionally connected to a first chamber 3a of the pressure medium reservoir 3 via a shut-off valve 11. Via this shut-off valve 11, the pressure source 2 can also suck pressure medium from the first chamber 3a of the pressure medium reservoir 3. However, it is also possible for the pressure medium pump 10 to pump pressure medium from the second chamber 3b of the pressure medium reservoir 3 to the first chamber 3a of the pressure medium reservoir 3 via this shut-off valve 11 in order to make pressure medium available for the operation of the first brake control circuit 6a.

[0037] FIG. 2 illustrates a leak in one wheel brake 7b of the second brake control circuit 6b on the front axle using the brake system 1 of FIG. 1 as an example. Identical parts have the same reference numerals. When the brake system 1 is in the idle state, the valves that connect the wheel brakes 7a-7d to the first chamber 3a of the pressure medium reservoir 3 are opened to create a depressurized state. In particular, the shut-off valve 11, the pressure supply valve 5, the brake circuit shut-off valve 4, and the inlet valves 8a-8d of the brake control circuits 6a, 6b are opened. However, this allows the first chamber 3a of the pressure medium reservoir 3 to empty due to the leak at the front axle. This is diagrammatically indicated by the thick connecting line from the first chamber 3a of the pressure medium reservoir 3 via the opening valves 11, 5, 4, and 8b to the leaking front wheel brake 7b.

[0038] Nevertheless, according to the invention, in order to ensure that the brake system 1 can continue to operate at least in emergency driving, first, in the case of a leaking front axle, all pressure medium still available in the brake system 1 is pumped into the pressure source 2 and / or the first chamber 3a of the pressure medium reservoir 3 by the pressure medium pump 10. The available pressure medium is in the pressure source 2 and the first chamber 3a of the pressure medium reservoir 3 connected thereto. The brake circuit shut-off valve 4 and the inlet valves 8a, 8b of the second brake control circuit 6b of the front axle are then closed. In FIG. 3, this re-pumping operation is shown by the bold line between the second chamber 3b of the pressure medium reservoir 3 and the pressure source 2 and the first chamber 3a of the pressure medium reservoir 3. Pumping pressure medium from the second chamber 3b of the pressure medium reservoir 3 into the first chamber 3a of the pressure medium reservoir 3 via the shut-off valve 11 is an optional possibility.

[0039] In this state of the brake system 1, the first brake control circuit 6a can now be operated using the pressure source 2 from the pressure medium in the pressure source 2 and / or the pressure medium in the first chamber 3a of the pressure medium reservoir 3, while the first brake control circuit 6b is blocked due to leakage.

[0040] However, when the brake system 1 is put into idle, the pressure medium in the first chamber 3a of the pressure medium reservoir 3 and in the pressure source 2 must be re-established, as otherwise it can or will actually be expelled by leakage at the front axle due to an open valve at idle.

[0041] 4 by pumping the pressure medium from the pressure source 2 and from the first chamber 3a of the pressure medium reservoir 3 back into the second chamber 3b of the pressure medium reservoir 3 with the aid of the pressure source 2, so that the pressure medium is secured there by closing the outlet valves 9a-9d. For this purpose, the pressure source 2 draws the pressure medium from the first chamber 3a of the pressure medium reservoir 3 via a check or shut-off valve 11 and pumps the pressure medium back into the second chamber 3b of the pressure medium reservoir 3 via the first pressure line 14, the pressure supply valve 5, the second pressure line 15, at least one open inlet valve 8a-8d, at least one associated outlet valve 9a-9d and the outlet connecting line 13, and then secures the pressure medium therein by closing the outlet valves 9a-9d.

[0042] In a subsequent operating state of the brake system 1, the pressure medium thus secured can be pumped back into the pressure source 2 and / or into the first chamber 3a of the pressure medium reservoir 3, as explained in relation to FIG. 3.

[0043] 5 shows another highly schematic and exemplary embodiment of a brake system 1 for a motor vehicle. According to the exemplary embodiment, the brake system 1 likewise has four hydraulically operated wheel brakes 7a, 7b, 7c and 7d. According to the exemplary embodiment, the wheel brakes 7a and 7b are assigned to the front axle, and the wheel brakes 7c and 7d are assigned to the rear axle of the motor vehicle. The wheel brakes 7a and 7b of the front axle are part of the second brake control circuit 6b, and the wheel brakes 7c and 7d of the rear axle are part of the first brake control circuit 6a.

[0044] The brake system 1 likewise has a pressure medium reservoir 3 with, in this case, three at least partially separated chambers, the first chamber 3a being assigned a first tank connection, the second chamber 3b being assigned a second tank connection and the third chamber 3c being assigned a third tank connection.

[0045] In the brake system 1, the electrically operated pressure source 2 as well as the wheel-specific brake pressure regulating valves 8a, 8b, 8c, 8d, 9a, 9b, 9c, 9d are arranged as components of brake control circuits 6a, 6b. The outlet valves 9a, 9b, 9c, 9d contained in the brake control circuits 6a, 6b are connected to the second chamber 3b of the pressure medium reservoir 3 via a common outlet connection line 31.

[0046] On the pressure side, the pressure source 2 is connected to the inlet valves 8c and 8d of the first brake control circuit 6a via the pressure supply valve 5. The wheel brakes 7c and 7d can therefore be actuated directly by the pressure source 2.

[0047] The pressure source 2 is additionally connected to the inlet valves 8a, 8b of the second brake control circuit 6b via the pressure supply valve 5 and the brake circuit shut-off valve 33. The wheel brakes 7a and 7b of the front axle can thus likewise be actuated directly by the pressure source 2. However, it is also possible to shut off the second brake control circuit 6b from the pressure source 2 by the brake circuit shut-off valve 33, for example if a leak is detected.

[0048] The pressure source 2 can be isolated from the brake control circuit 6a, 6b by means of the pressure supply valve 5. Additionally, the pressure supply valve 5 can be closed in such a way that by retracting it the pressure source 2 can draw pressure medium from the first chamber 3a of the pressure medium reservoir 3 via the shut-off valve 34 or from the third chamber 3c via the non-return valve 4.

[0049] At least one electronic control unit 20 is provided, which is shown highly diagrammatically in Figure 1. Each electronic control unit includes electrical and / or electronic elements (e.g., microcontrollers, power modules, valve drivers, other electronic components, etc.) for operating electrically actuated components of the brake system 1, and optionally associated sensors. For clarity, connection lines to such actuators and sensors have been omitted.

[0050] An electronic control unit 20 controls the pressure source 2. According to this example, the pressure source 2 is supplied with energy via the electronic control unit 20 (from an electrical energy source, not shown).

[0051] The brake system 1 additionally comprises a pressure medium pump 30, which on the inlet side is connected via an outlet connecting line 31 to a pressure medium tank 32, which in turn is connected to the second chamber 3b of the pressure medium reservoir 3. On the output side, the pressure medium pump 30 is connected to the inlet valves 8a, 8b of the second brake control circuit 6b.

[0052] The pressure medium pump 30 is thus able to supply pressure medium to the second brake control circuit 6b and to operate the second brake control circuit 6b. The pressure medium pump 30 can likewise be supplied with energy and controlled by the control device 20, in particular switched on and off.

[0053] The pressure medium pump 30 is likewise connected to the first brake control circuit 6a via a brake circuit shut-off valve 33, so that the pressure medium pump 30 can also supply pressure medium to the first brake control circuit 6a via this brake circuit shut-off valve 33.

[0054] The electrically controlled pressure medium pump 30 is designed in the exemplary embodiment of FIG. 5 as a two-piston pump, the two pressure sides and the two suction sides of which are in each case connected to one another.

[0055] The pressure medium pump 30 has check valves on both its pressure and suction sides, so that it can only deliver pressure medium in the direction from the pressure medium tank 32 to the brake control circuits 6a, 6b.

[0056] In the brake system 1 of Figure 5, the pressure source 2 is additionally connected to the first chamber 3a of the pressure medium reservoir 3 via a shut-off valve 34. Via this shut-off valve 34, the pressure source 2 can aspirate pressure medium from the first chamber 3a of the pressure medium reservoir 3. However, it is also possible to pump pressure medium from the pressure source 2 into the first chamber 3a of the pressure medium reservoir 3 via this shut-off valve 34.

[0057] 5, the braking system 1 is divided into two subsystems 35 and 36, the first subsystem 35 essentially comprising the pressure source 2, a shut-off valve 34 and a pressure medium reservoir 3, and the second subsystem 36 comprising the pressure medium pump 30, a further valve and a further pressure medium tank 32. An electronic pedal 37 generates signals relating to the driver's braking request and transmits these signals to the two subsystems 35, 36 of the braking system 1.

[0058] Since the pressure source 2 does not run out in the event of a wheel leak, it is sufficient to fill the first pressure line 14 from the second chamber 3b by means of the pressure medium pump 10 or 30 for emergency driving operations.

Claims

1. 1. A method for operating a brake system (1) when a leak is detected, the method being formed by an electrically operated pressure source (2) connected to a first brake control circuit (6a) via a first pressure line (14) and a pressure supply valve (5) and to a second brake control circuit (6b) via said pressure supply valve (5) and additionally via a brake circuit shut-off valve (4; 33), said electrically operated pressure source (2) supplying pressurized pressure medium from a first chamber (3a) and / or a third chamber (3c) of a pressure medium reservoir (3) to said brake control circuits (6a, 6b), comprising: each brake control circuit (6a, 6b) has a respective inlet valve (8a-8d), each brake control circuit (6a, 6b) is connected to the pressure source (2) via said respective inlet valve (8a-8d), each brake control circuit (6a, 6b) has a respective outlet valve (9a-9d), each brake control circuit (6a, 6b) is connected to the second chamber (3b) of the pressure medium reservoir (3) via said respective outlet valve (9a-9d), all said outlet valves (9a-9d) are connected to the second chamber (3b) of the pressure medium reservoir (3) via a common outlet connection line (13; 31); the pressure source (2) is connected to the first chamber (3a) or the third chamber (3c) via a check valve (37); the common outlet connection line (13; 31) is connected to the second brake control circuit (6b) via a pressure medium pump (10; 30); the pressure source (2) is connected to the first chamber (3a) of the pressure medium reservoir (3) via a first valve (11; 34), The step in the event of a leakage in the second brake control circuit (6b), for further operation of the brake system (1) using only the first brake control circuit (6a), the valve enabling the connection of the second chamber (3b) of the pressure medium reservoir (3) with the pressure source (2) and / or the first chamber (3a) of the pressure medium reservoir (3) via the pressure medium pump (10; 30) is opened, and the pressure medium pump (10; 30) is operated in such a way that pressure medium is pumped from the second chamber (3b) of the pressure medium reservoir (3) into the pressure source (2) and / or the first chamber (3a) of the pressure medium reservoir (3) through the resulting connection, The brake circuit shut-off valve (4; 33) is then closed and the first brake control circuit (6a) is operated by the pressure source (2) with pressure medium from the first chamber (3a) of the pressure medium reservoir (3), When the brake system is put into the idle state, firstly, pressure medium is transferred from the pressure source (2) into the second chamber (3b) of the pressure medium reservoir (3) by operating the pressure source (2). A method comprising the steps.

2. 2. The method according to claim 1, wherein in a third step after pumping the pressure medium of the pressure source (2) into the second chamber (3b) of the pressure medium reservoir (3), pressure medium is drawn from the first chamber (3a) of the pressure medium reservoir (3) into the pressure source (2) and then pumped into the second chamber (3b) of the pressure medium reservoir (3).

3. 3. The method according to claim 2, wherein the re-pumping of the pressure medium from the first chamber (3a) of the pressure medium reservoir (3) into the pressure source (2) and from the pressure source (2) into the second chamber (3b) of the pressure medium reservoir (3) is performed several times until the pressure medium of the first chamber (3a) of the pressure medium reservoir (3) is pumped into the second chamber (3b) of the pressure medium reservoir (3).

4. when a leak occurs in the second brake control circuit (6 b), the pressure supply valve (5) and the brake circuit shut-off valve (4) are opened and the pressure medium pump (10; 30) is activated in order to fill the pressure source (2) with pressure medium from the second chamber (3 b) of the pressure medium reservoir (3) for further operation of the brake system only with the first brake control circuit (6 b), 4. The method according to claim 1, wherein, when the brake system (1) is put into an idle state, first the first valve (11; 34) and the brake circuit shut-off valve (4; 33) are closed, at least one outlet valve (9c, 9d) and one inlet valve (8c, 8d) of the first brake control circuit (6a) and the pressure supply valve (5) are opened, and pressure medium from the pressure source (2) is conveyed into the second chamber (3b) of the pressure medium reservoir (3) by operating the pressure source (2).

5. 1. A method for operating a brake system (1) when a leak is detected, the method being formed by an electrically operated pressure source (2) connected to a first brake control circuit (6a) via a first pressure line (14) and a pressure supply valve (5) and to a second brake control circuit (6b) via said pressure supply valve (5) and additionally via a brake circuit shut-off valve (4; 33), said electrically operated pressure source (2) supplying pressurized pressure medium from a first chamber (3a) and / or a third chamber (3c) of a pressure medium reservoir (3) to said brake control circuits (6a, 6b), comprising: each brake control circuit (6a, 6b) has a respective inlet valve (8a-8d), each brake control circuit (6a, 6b) is connected to the pressure source (2) via said respective inlet valve (8a-8d), each brake control circuit (6a, 6b) has a respective outlet valve (9a-9d), each brake control circuit (6a, 6b) is connected to the second chamber (3b) of the pressure medium reservoir (3) via said respective outlet valve (9a-9d), all said outlet valves (9a-9d) are connected to the second chamber (3b) of the pressure medium reservoir (3) via a common outlet connection line (13; 31); the pressure source (2) is connected to the first chamber (3a) or the third chamber (3c) via a check valve (37); the common outlet connection line (13; 31) is connected to the second brake control circuit (6b) via a pressure medium pump (10; 30); the pressure source (2) is connected to the first chamber (3a) of the pressure medium reservoir (3) via a first valve (11; 34), The step in the event of a leakage in the second brake control circuit (6b), for further operation of the brake system (1) using only the first brake control circuit (6a), the valve enabling connection between the second chamber (3b) of the pressure medium reservoir (3) and the first pressure line (14) via the pressure medium pump (10; 30) is opened, and the pressure medium pump (10; 30) is operated in such a way that pressure medium is pumped from the second chamber (3b) of the pressure medium reservoir (3) into the first pressure line (14) through the resulting connection, The brake circuit shut-off valve (4; 33) is then closed and the first brake control circuit (6a) is operated by the pressure source (2) with pressure medium from the first chamber (3a) of the pressure medium reservoir (3). A method comprising the steps.

6. A control device for a braking system, comprising a processor for carrying out the method of any one of claims 1 to 5.

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