DE102023212502A1 - Braking system for motor vehicles and method for its operation - Google Patents

Abstract

Brake system for a motor vehicle with a first pressure supply device (5), a pressure fluid reservoir (4), a first brake circuit (I) with a first brake circuit pressure line section (12a) and a second brake circuit (II) with a second brake circuit pressure line section (12b), wherein the first pressure supply device (5) is hydraulically connected to the first brake circuit pressure line section (12a) via a first connection valve (26a) and is hydraulically connected to the second brake circuit pressure line section (12a, 12b) via a second connection valve (26b), an inlet valve (6a-6d) for each wheel brake (8, 9, 10, 11), wherein the inlet connections of the inlet valves (6a, 6b) of the first wheel brakes (8, 9) are connected to the first brake circuit pressure line section (12a) and the inlet connections of the inlet valves (6c, 6d) of the second Wheel brakes (10, 11) are connected to the second brake circuit pressure line section (12b), and a second pressure supply device (60) with a pump (60a, 60b) for each brake circuit (I, II), the pressure side (160a, 160b) of which is connected to the inlet valves of the wheel brakes assigned to the brake circuit, the suction sides (161a, 161b) of the pumps (60a, 60b) being connected to one another and to the pressure medium reservoir (4) via a separating valve (23), and a method for operating a brake system.

Description

The invention relates to a braking system according to the preamble of claim 1 and to a method for operating such a braking system.

From the WO 2020/229484 A1 A dual-circuit "brake-by-wire" braking system for motor vehicles is known, which comprises a brake pedal-actuated tandem master brake cylinder, a simulation device hydraulically connected to the tandem master brake cylinder, a first electrically controllable pressure supply device, a second electrically controllable pressure supply device with a pump per brake circuit, a pressure modulation unit for setting wheel-specific brake pressures in the form of an inlet and an outlet valve for each wheel brake, various other electrically controllable valves, and two electronic control and regulation units. The pumps and the pressure modulation unit are arranged in a downstream module, which has a dual-circuit design with two hydraulically separated brake circuits and has exactly one connection per brake circuit for connection to the master brake cylinder and the first electrically controllable pressure supply device of the main module.

The object of the present invention is to provide a cost-effective braking system for a motor vehicle and a method for operating the same, which is suitable for highly automated driving. In particular, the braking system should be able to dispense with a brake pedal-actuated master brake cylinder (i.e., a hydraulic fallback system), the braking system should comprise fewer electrically controllable valves, and yet the braking system should still be able to achieve a sufficient braking effect even in the event of a fault, for example, if one of the two pressure supply devices or one of the two electronic control and regulation units fails, or if a leak occurs in one of the two brake circuits, e.g., at one of the wheel brakes.

This object is achieved according to the invention by a braking system according to claim 1 and a method for its operation according to claims 11 and 13.

The invention is based on the idea that the brake system comprises a first electrically controllable pressure supply device, a pressure fluid reservoir and a first brake circuit with a first brake circuit pressure line section for connection to first wheel brakes and a second brake circuit with a second brake circuit pressure line section for connection to second wheel brakes, wherein the first pressure supply device is hydraulically connected to the first brake circuit pressure line section via an electrically actuated first connection valve and is hydraulically connected to the second brake circuit pressure line section via an electrically actuated second connection valve. The brake system further comprises an inlet valve for each first and second wheel brake, wherein the inlet ports of the inlet valves of the first wheel brakes are connected to the first brake circuit pressure line section, and the inlet ports of the inlet valves of the second wheel brakes are connected to the second brake circuit pressure line section. A second electrically controllable pressure supply device with a pump for each brake circuit, the pressure side of which is connected to the inlet valves of the wheel brakes assigned to the brake circuit. The suction sides of the pumps are interconnected and connected to the pressure fluid reservoir via an electrically actuated isolating valve.

The braking system according to the invention offers the advantage of being suitable for highly automated driving while requiring only a few electrically actuated valves. The second pressure supply device, with one pump per brake circuit, allows the motor vehicle to be adequately actuated using pressure fluid from the pressure fluid reservoir, even in the event of a leak in one of the two brake circuits. This eliminates the need for a hydraulic fallback system in the form of a brake pedal-actuated master cylinder.

Preferably, the suction sides of the pumps are directly connected to each other. The term "directly connected" means, in particular, that no valve is arranged between the suction sides of the pumps.

Preferably, the isolating valve is connected with one of its connections to the pressure medium reservoir and with another of its connections to the suction sides of the pumps.

The isolation valve is preferably designed to be open when de-energized. This allows the pumps to draw pressure fluid from the pressure fluid reservoir even if the electrical control of the isolation valve fails.

Preferably, no further electrically actuated valve is arranged in the hydraulic connection between the suction sides of the pumps and the pressure fluid reservoir besides the isolating valve. This prevents the flow resistance of the hydraulic connection from increasing further. Furthermore, the manufacturing costs of the brake system are reduced.

Preferably, at least one check valve opening toward the suction sides of the pumps is connected in parallel with the isolating valve. This increases the pressure medium volume flow during suction of the pumps.

By means of the two electrically actuated connection valves, the two brake circuit pressure line sections can be separated from each other and from the first pressure supply device or connected to each other.

Preferably, the first and second sequence valves are closed when de-energized and designed such that the first pressure supply device can open or overflow the sequence valves in their de-energized state by building up pressure (in the pressure-buildup direction of the sequence valves). This is advantageous because, when the brake system is de-energized, there is a brake circuit separation (separation of the first brake circuit pressure line section from the second brake circuit pressure line section). However, in the event of a failure in the control of the sequence valves, it is possible to pressurize both brake circuit pressure line sections by building up pressure through the first pressure supply device, since the sequence valves are opened or overflowed by the pressure buildup.

Preferably, no further electrically actuated valve is arranged in the hydraulic connection between the first pressure supply device and the inlet valves of the first wheel brakes, apart from the first activation valve, and no further electrically actuated valve is arranged in the hydraulic connection between the first pressure supply device and the inlet valves of the second wheel brakes, apart from the second activation valve. This allows the manufacturing costs of the brake system to be further reduced.

Preferably, the first electrically controllable pressure supply device is designed as a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which can be advanced and retracted by an electromechanical actuator. Particularly preferably, the first pressure supply device comprises only a single pressure chamber, and the pressure chamber is hydraulically connected to the first brake circuit pressure line section via the first connection valve and to the second brake circuit pressure line section via the second connection valve.

Preferably, the pressure medium reservoir is designed as a pressure medium reservoir under atmospheric pressure.

Preferably, the braking system comprises, in addition to the inlet valve for each first and second wheel brake, an outlet valve for each first and second wheel brake. Particularly preferably, the outlet valves are hydraulically connected to the pressure fluid reservoir via the isolation valve. This eliminates the need for an additional return line for the outlet valves. The isolation valve, which is designed to be open when de-energized, generally allows pressure fluid to flow from the wheel brakes into the pressure fluid reservoir via one or more outlet valves.

The braking system preferably comprises a first electronic control and regulating unit and a second electronic control and regulating unit, which is independent of the first electronic control and regulating unit. The first pressure supply device and the isolating valve are controlled by the first electronic control and regulating unit, and the first and second connection valves, the second pressure supply device and the inlet valves, and optionally the outlet valves, are controlled by the second electronic control and regulating unit. This ensures sufficient braking action even if one of the electronic control and regulating units fails. Furthermore, independent control of the first and second electrically controllable pressure supply devices is advantageously ensured.

Preferably, the first pressure supply device is hydraulically connected to the pressure fluid reservoir via a suction valve, wherein the suction valve is connected to a first chamber of the pressure fluid reservoir and the isolating valve is connected to a second chamber of the pressure fluid reservoir. Particularly preferably, the first pressure supply device is hydraulically connected to the pressure fluid reservoir, in particular to the first chamber of the pressure fluid reservoir, via a check valve opening in the direction of the first pressure supply device. A loss of pressure fluid from both chambers of the pressure fluid reservoir can thus be avoided even in the deactivated state and without the consumption of electrical energy.

Particularly preferably, the pressure chamber of the first pressure supply device is hydraulically connected to the pressure medium reservoir via the suction valve, in particular via the check valve opening in the direction of the first pressure supply device, wherein the suction valve is connected to the first chamber of the pressure medium reservoir and the isolating valve is connected to the second chamber of the pressure medium reservoir.

Preferably, a level measuring device for determining a pressure medium level in the pressure medium reservoir is provided in the pressure medium reservoir. Particularly preferably, the level measuring device is provided for determining a pressure medium level in the first chamber of the pressure medium reservoir.

According to a preferred development of the invention, an electrically actuated pressure control valve is connected in parallel with each pump. This enables individual pressure control for each brake circuit. Particularly preferably, an electrically actuated, normally open pressure control valve is connected in parallel with each pump. Particularly preferably, a check valve closing toward the suction side of the pump is connected in parallel with each pressure control valve.

Preferably, the pressure control valves connected in parallel to the pumps are controlled by the same electronic control and regulation unit as the second pressure supply device.

According to a preferred embodiment of the brake system according to the invention, the first pressure supply device and the isolating valve are arranged in a first independent module and the first and second connection valves, the second pressure supply device and the inlet valves are arranged in a second independent module.

Particularly preferably, the outlet valves are also arranged in the second module.

Particularly preferably, the pressure control valves are also arranged in the second module.

Particularly preferably, the first electronic control and regulation unit is arranged in or on the first module, and the second electronic control and regulation unit is arranged in or on the second module. This advantageously ensures independent control of the first and second electrically controllable pressure supply devices.

Preferably, the electrically controllable components of the first module are controlled by the first electronic control and regulation unit. Particularly preferably, the electrically controllable components of the first module are controlled exclusively by the first electronic control and regulation unit.

Particularly preferably, the first pressure supply device comprises a motor position sensor which is connected to the first electronic control and regulation unit.

Preferably, the electrically controllable components of the second module are controlled by the second electronic control and regulation unit. Particularly preferably, the electrically controllable components of the second module are controlled exclusively by the second electronic control and regulation unit.

Particularly preferably, the second module comprises a pressure sensor which is connected to the second electronic control and regulation unit.

Preferably, one or the pressure sensor is arranged on one of the brake circuit pressure line sections.

Preferably, the first module does not comprise any further electrically actuated valve besides the isolating valve.

Preferably, the second module does not comprise any further electrically actuated valve in addition to the first and second activation valves, the inlet and outlet valves for each wheel brake and the two pressure control valves.

Preferably, the first module and the second module are hydraulically connected to each other by only two connecting lines. The isolation valve is or are arranged in the first module.

The pumps of the second pressure supply device are preferably driven jointly by an electric motor.

The invention also relates to methods for operating a braking system according to the invention.

According to the invention, to operate a braking system according to the invention, in a predetermined situation of the braking system, the isolating valve is closed and the first pressure supply device is controlled such that the de-energized first activation valve and the de-energized second activation valve are opened, forced open, or overflowed. The wheel brakes are thus actuated.

Preferably, the isolating valve is closed by means of the first electronic control and regulation unit and the first pressure supply device is controlled in this way.

The method according to the invention is preferably carried out in the event of a failure of the second electronic control and regulation unit (first predetermined situation).

Alternatively or additionally, the method according to the invention is preferably carried out in the event of a failure of an electrical component of the second module (second predetermined situation).

The method according to the invention is preferably carried out in the event of a failure of an electrical control of the connection valves (third predetermined situation).

Preferably, pressure reduction is carried out by opening the isolating valve, in particular by means of the first electronic control and regulation unit.

According to the invention, in order to operate a brake system according to the invention, the integrity of the hydraulic connection between the second pressure supply device and the isolating valve is checked when a loss of pressure medium is detected.

This is preferably done by comparing the sensor signals of motor position and pressure and evaluating whether these are in a given relationship, e.g., one expected for an integrated system. Other methods are generally known and will not be described further here.

Preferably, once the integrity of the hydraulic connection has been confirmed, the second pressure supply device is activated to build up pressure. The sequence valves are particularly preferably not activated or energized. The brake circuit separation by the sequence valves thus allows a braking effect on the wheel brakes of the other brake circuit even in the event of a leak in one of the brake circuits.

Preferably, the loss of pressure medium is detected by means of a level measuring device arranged in the pressure medium reservoir.

Further preferred embodiments of the invention emerge from the claims and the following description with reference to figures.

• 1 ein Ausführungsbeispiel einer erfindungsgemäßen Bremsanlage,
• 2 die erfindungsgemäße Bremsanlage der 1 bei einer Bremsung im fehlerfreien Fall der Bremsanlage,
• 3 die erfindungsgemäße Bremsanlage der 1 während eines Ausfalls der zweiten elektronischen Steuer- und Regeleinheit, und
• 4 eine erfindungsgemäße Bremsanlage im Falle einer Leckage.

They show schematically:

• 1 an embodiment of a brake system according to the invention,
• 2 the braking system according to the invention 1 during braking in the event of a faultless braking system,
• 3 the braking system according to the invention 1 during a failure of the second electronic control unit, and
• 4 a braking system according to the invention in the event of a leak.

In 1 An embodiment of a brake system according to the invention is shown schematically. According to the example, the brake system is designed to actuate four hydraulically actuated wheel brakes 8-11 of a motor vehicle; expansion to more wheel brakes is easily possible. The brake system comprises a first electrically controllable pressure supply device 5, a second electrically controllable pressure supply device 60, a pressure fluid reservoir 4, and, for each wheel brake 8-11, an inlet valve 6a-6d and an outlet valve 7a-7d.

The pressure medium reservoir 4, which is under atmospheric pressure, advantageously comprises two chambers 401, 402, which are separated from each other by a bulkhead.

For example, the brake system for leakage monitoring comprises a level measuring device 55 for determining a pressure medium level in the pressure medium reservoir 4. According to the embodiment of the 1 the level measuring device 55 is arranged in the chamber 402.

The inlet and outlet valves 6a-6d, 7a-7d and the second pressure supply device 60 are part of a so-called wheel pressure supply device.

The wheel pressure supply device has a dual-circuit design, with the wheel brakes 8, 9 being assigned to a first brake circuit I with a first brake circuit pressure line section 12a and the wheel brakes 10, 11 being assigned to a second brake circuit II with a second brake circuit pressure line section 12b.

The inlet and outlet valves 6a-6d, 7a-7d are hydraulically interconnected in pairs via central connections and connected to the respective wheel brakes 8, 9, 10, 11. The input connections of the inlet valves 6a, 6b of the first brake circuit I (assigned to the wheel brakes 8 and 9) are connected to the first brake circuit pressure line section 12a, and the input connections of the inlet valves 6c, 6d of the second brake circuit II (assigned to the wheel brakes 10 and 11) are connected to the second brake circuit pressure line section 12b. A check valve 50a-50d opening toward the brake circuit pressure line sections 12a, 12b is connected in parallel to each of the inlet valves 6a-6d.

The output connections of the outlet valves 7a-7d are connected via a common connecting line device 14 is connected to the pressure medium reservoir 4, for example to its chamber 402.

The second pressure supply device 60 comprises a first pump 60a and a second pump 60b, which are driven by a common electric motor M. Each pump 60a or 60b is assigned to one of the brake circuits I or II.

A pressure control valve 61a or 61b is connected in parallel to each pump 60a or 60b. Pressure control valves 61a, 61b are advantageously designed as analogue controllable, normally open valves. Furthermore, a check valve 64a or 64b opening in the flow direction toward the wheel brakes 8-11 is preferably connected in parallel to each pressure control valve 61a or 61b.

The pressure side 160a or 160b of the pump 60a or 60b is connected to the corresponding associated brake circuit pressure line section 12a or 12b, and thus to the inlet valves 6a, 6b or 6c, 6d of the corresponding brake circuit I or II.

The suction sides 161a, 161b of the pumps 60a, 60b are connected to one another, for example. Advantageously, the suction sides 161a, 161b of the pumps 60a, 60b are connected directly to one another, e.g., without the interposition of an electrically actuated valve. The suction sides 161a, 161b of the pumps 60a, 60b are connected, for example, to the pressure medium reservoir 4 via the connecting line 14, via which the outlet valves 7a-7d are also connected to the pressure medium reservoir 4. A common connecting line 14, so to speak, which is used as a discharge line for the outlet valves 7a-7d and as a suction line for the second pressure supply device 60, is advantageous.

A separating valve 23 is arranged in the connecting line 14. The separating valve 23 is designed as an electrically actuated, preferably normally open, valve, e.g., a 2/2-way valve. Preferably, a check valve 56 opening in the direction of the suction sides 161a, 161b is connected in parallel with the separating valve 23. For example, the separating valve 23 further comprises an integrated check valve, which in 1 shown but not specified in more detail.

Thus, the suction sides 161a, 161b of the pumps 60a, 60b are connected to the pressure medium reservoir 4, for example, to its chamber 402, via the isolating valve 23. The hydraulic connection between the suction sides 161a, 161b of the second pressure supply device 60 and the pressure medium reservoir 4 can be shut off by means of the isolating valve 23. Likewise, the hydraulic connection between the outlet valves 7a-7d and the pressure medium reservoir 4 is shut off by the isolating valve 23.

Preferably, no further electrically actuated valve is arranged in the hydraulic connection between the suction sides 161a, 161b of the second pressure supply device 60 and the pressure medium reservoir 4 besides the isolating valve 23.

The pressure medium volume required for pressure build-up by means of the pressure supply device 60 can be supplied to the latter via the connecting line 14 by means of the isolating valve 23 and the check valve 56 from the pressure medium reservoir 4.

To detect the pressure prevailing in the brake circuit pressure line section 12b, a preferably redundant pressure sensor 20 is provided, which is advantageously part of the wheel pressure supply device.

For example, the first pressure supply device 5 is part of a so-called circular pressure supply device, which is connected to the wheel brakes 8, 9, 10, 11 via the wheel pressure supply device.

For example, isolation valve 23 is also part of the circuit pressure supply device.

The first electrically controllable pressure supply device 5 is designed as a hydraulic cylinder-piston arrangement with a hydraulic pressure chamber 37, the piston 36 of which can be actuated by a schematically indicated electric motor 35 with the interposition of a rotation-translation gear 39, also shown schematically, in particular can be moved forwards and backwards in order to build up and reduce pressure in the pressure chamber 37. The piston 36 delimits the pressure chamber 37, which is, for example, the only one, of the pressure supply device 5. To control the electric motor, a rotor position sensor 44, which detects the rotor position of the electric motor 35 and is only indicated schematically, is provided.

For the replenishment of pressure medium, the pressure supply device 5 or its pressure chamber 37 is hydraulically connected to the pressure medium reservoir 4, for example, to its first chamber 401, via a replenishment line 54, in which a replenishment valve 53 is arranged. This hydraulic connection is independent of the actuation state of the piston 36. The pressure The supply device 5 advantageously has no sniffing holes. The suction valve 53 is designed as a check valve 53 closing in the direction of the pressure medium reservoir 4.

The pressure supply device 5 is separably hydraulically connected to the first brake circuit pressure line section 12a (or the first brake circuit I) via a first connection valve 26a and separably hydraulically connected to the brake circuit pressure line section 12b (or the second brake circuit II) via a second connection valve 26b. The connection valves 26a, 26b are designed as electrically actuated valves, e.g., 2/2-way valves. The connection valves 26a, 26b are preferably designed to be closed when de-energized and are constructed such that the pressure supply device 5 can open or overflow the de-energized connection valves 26a, 26b by a pressure buildup (in the pressure buildup direction of the connection valves), advantageously without a function-limiting pressure loss.

Thus, when the piston 36 is displaced in the brake actuation direction (regardless of the current supply state of the activation valves 26a, 26b), pressure medium from the pressure chamber 37 passes into the brake circuit pressure line sections 12a, 12b, and thus into the wheel pressure supply device, and thus into the wheel brakes 8, 9, 10, 11 for their actuation.

For example, a system pressure line 38 is connected to the pressure chamber 37 of the first electrically controllable pressure source 5, which line is divided into two line sections at a point 15, one line section being connected to the connection valve 26a and the other line section being connected to the connection valve 26b.

Preferably, no further electrically actuated valve, particularly preferably no further valve (i.e., check valve or electrically/hydraulically/mechanically actuated valve), is arranged in the hydraulic connection between the first pressure supply device 5 and the brake circuit pressure line section 12a besides the connection valve 26a. Preferably, no further electrically actuated valve, particularly preferably no further valve, is arranged in the hydraulic connection between the first pressure supply device 5 and the brake circuit pressure line section 12b besides the connection valve 26b.

For example, the connection valves 26a, 26b are part of the wheel pressure supply device.

The brake system comprises, for example, a first structural unit or a first module 100, which is, for example, designed as a first electrohydraulic brake control unit (HECU 1) with a valve block HCU 1 and a first electronic control device 110 (ECU 1), and a second structural unit or a second module 200, which is, for example, designed as a second electrohydraulic brake control unit (HECU 2) with a valve block HCU 2 and a second electronic control device 210 (ECU 2). The pressure fluid reservoir 4 is arranged on the first module 100.

Advantageously, the first pressure supply device 5 and the isolation valve 23 are arranged in the first independent module (or the first structural unit) 100 (also called the circuit pressure supply module). The hydraulic components check valve 53 and check valve 56 are also arranged in the module 100. The sensor 44 is also arranged in or on the module 100.

The (first) electronic control and regulation unit (ECU 1) 110 is assigned to the circuit pressure supply device or the circuit pressure supply module 100. This control and regulation unit is provided for controlling the electrically actuated components of the device or module 100. The electronic control and regulation unit (ECU 1) 110 controls, in particular, the first pressure supply device 5 and the isolation valve 23.

Advantageously, the connection valves 26a, 26b, the second pressure supply device 60, and the inlet and outlet valves 6a-6d, 7a-7d are arranged in the second independent module (or second structural unit) 200 (the so-called wheel pressure supply module). The hydraulic components valves 61a, 61b, check valves 50a-50d, 64a, 64b, and the sensor 20 are also arranged in module 200.

The (second) electronic control and regulation unit (ECU 2) 210 is assigned to the wheel pressure supply device or the wheel pressure supply module 200. This control and regulation unit is provided for controlling the electrically actuated components of the device or the module 200. The (second) electronic control and regulation unit (ECU 2) 210 controls, in particular, the connection valves 26a, 26b, the second pressure supply device 60, and the inlet and outlet valves 6a-6d, 7a-7d, as well as, if necessary, the pressure control valves 61a, 61b.

For example, the pressure supply device 5 and the isolating valve 23, as well as possibly the suction line 54, the check valve 53 and/or the check valve 56 are arranged in or on the first valve block HCU 1 and the connection valves 26a, 26b, pressure supply device 60 and the inlet and outlet valves 6a-6d, 7a-7d, as well as possibly the pressure control valves 61a, 61b, the check valves 64a, 64b and/or the check valves 50a-50d, arranged in or on a second valve block HCU 2.

The system pressure line 38 comprises a first line section 38a, which connects the pressure chamber 37 within the valve block HCU 1 to a hydraulic (pressure) connection 120 of the first structural unit 100, a hydraulic connecting element 38b, which hydraulically connects the connection 120 to a hydraulic (pressure) connection 220 of the second structural unit 200, and a third line section 38c, which connects the connection 220 to the connection valves 26a, 26b within the valve block HCU 2. Connection 38b represents a hydraulic pressure connection between the first structural unit 100 and the second structural unit 200. This is a hydraulic connection for transmitting brake pressure to actuate the wheel brakes 8a-8d (hence a pressure connection). Connecting element 38b must therefore be designed to be pressure-resistant, e.g., as a pressure-resistant brake hose.

The connecting line 14 comprises a first line section 14a, which connects the outlet valves 7a-7d and the suction side 161a, 161b of the pressure supply device 60 within the valve block HCU 2 to a hydraulic connection 230 of the second structural unit 200, a hydraulic connecting element 14b, which hydraulically connects the connection 230 to a hydraulic connection 130 of the first structural unit 100, and a third line section 14c, which connects the connection 130 to the pressure medium reservoir 4 within the valve block HCU 1.

The electronic control unit 110 (ECU 1) is assigned to the valve block HCU 1, and the electronic control unit 210 (ECU 2) is assigned to the valve block HCU 2. Each electronic control unit 110, 210 comprises electrical and/or electronic elements (e.g., microcontrollers, power units, valve drivers, other electronic components, etc.) for controlling the electrically actuated components of the associated valve block (assembly) and, if necessary, for evaluating the signals from the sensors assigned to this valve block (assembly). The valve block and electronic control unit are advantageously designed, as is known, as an electrohydraulic brake control unit (HECU).

The pressure fluid reservoir 4 is advantageously arranged on the first structural unit/module 100. Accordingly, the level measuring device 55 is assigned to the first electronic control and regulation unit 110, i.e., the signals from the level measuring device 55 are fed to the electronic control and regulation unit 110, as are the signals from the rotor position sensor 44.

The electronic control and regulation units 110, 210 are advantageously connected to one another by means of a communication device (e.g. data bus) in order to be able to exchange data.

Advantageously, point 15 of the system pressure line 38 is located within the module 200, and advantageously, the outlet valves 7a-7d and the pressure supply device 60 are connected to a common connecting line 14. Thus, the two modules 100, 200 are connected to each other by only two hydraulic flow paths, namely the system pressure line 38 (via 38b) and the connecting line 14 (via 14b).

In 2 The braking system according to the invention is 1 during braking in a fault-free braking system situation. In a fault-free braking system situation, the activation valves 26a, 26b are opened, the pressure control valves 61a, 61b are closed, and the first pressure supply device 5 is activated to regulate the pressure in the wheel brakes 8-11. For this purpose, for example, the activation valves 26a, 26b, the pressure control valves 61a, 61b, and the first pressure supply device 5 are activated, which is indicated by the lightning symbols 70. Wheel-individual control of the brake pressures at the wheel brakes 8-11 (e.g., anti-lock control) is possible using the inlet and outlet valves 6a-6d, 7a-7d.

For this purpose, the pressure supply device 5 is controlled by means of the first electronic control and regulation unit 110, and the connection valves 26a, 26b, the pressure control valves 61a, 61b and, if applicable, the inlet and outlet valves 6a-6d, 7a-7d are controlled by means of the second electronic control and regulation unit 210.

The pressure provided by the pressure supply device 5 is transmitted to the wheel brakes 8-11 via the system pressure line 38, the connection valves 26a, 26b, the brake circuit pressure line sections 12a and 12b, and the inlet valves 6a-6d. The pressure medium is prevented from flowing out by the closed pressure control valves 61a, 61b and the normally closed outlet valves 7a-7d.

3 The braking system according to the invention is 1 during a failure (indicated by the symbol 80) of the second electronic control and regulation unit 210. In this case, the pressure supply device 60 and the valves of the second module 200, in particular the normally closed connection valves 26a, 26b, are not activated. For braking, therefore, the isolating valve 23 is closed and the first pressure supply device 5 is activated. The first pressure supply device 5 and the isolating valve 23 are activated by the first electronic control and regulation unit 110, which is indicated by the lightning symbols 70. This means that the (circuit pressure supply) module 100 can generate braking pressure in the wheel brakes 8-11 independently of the module 200 by closing the isolating valve 23 and pressing open (or overflowing) the activation valves 26a, 26b by the pressure supply device 5.

The pressure provided by the pressure supply device 5 is transmitted by pressing the connection valves 26a, 26b into the brake circuit pressure line sections 12a and 12b and via the inlet valves 6a-6d into the wheel brakes 8-11. The closed isolation valve 23 prevents the pressure medium from flowing out.

A desired pressure reduction is preferably achieved by opening the isolation valve 23.

Anti-lock control is possible by modulating the pressure of the pressure supply device 5, but not on a wheel-by-wheel basis.

4 a brake system according to the invention is shown in the event of a leak (indicated by the two symbols 90) at the wheel brake 11. The exemplary brake system of the 4 differs from the exemplary braking system of the 1 to 3 in that the level measuring device 55 is arranged in the chamber 401 of the pressure medium reservoir 4.

If a loss of pressure medium is detected, the hydraulic connection 14 between the second pressure supply device 60, or the module 200, and the isolation valve 23 is advantageously first checked. If this connection is OK, the wheel brakes 8-11 are then actuated by the module 200. For this purpose, the second pressure supply device 60 and, if necessary, the pressure control valves 61a, 61b for pressure control are activated, which is indicated by the lightning symbols 70.

The pressure generated by the respective pump 60a or 60b is passed on to the associated brake circuit pressure line section 12a or 12b and via the corresponding inlet valves 6a, 6b or 6c, 6d to the wheel brakes 8, 9 or 10, 11.

The normally closed connection valves 26a, 26b prevent pressure medium from flowing into the module 100, since the connection valves 26a, 26b are not opened by the pressure of the second pressure supply device 60 in their pressure reduction direction (i.e. from the wheel brakes/brake circuit pressure line sections 12a, 12b in the direction of the pressure supply device 5).

A discharge of pressure medium into the pressure medium reservoir 4 is prevented by the driven pumps 60a, 60b and the (at least partially) closed pressure control valves 61a, 61b as well as the normally closed outlet valves 7a-7d.

A loss of pressure medium can, for example, be easily detected by means of the level measuring device 55 arranged in the pressure medium reservoir 4.

A leak in one wheel brake circuit can thus cause a maximum loss of braking effect on two of the four wheel brakes 8-11, due to a passive brake circuit separation. The activation valves 26a, 26b are closed when de-energized.

The loss of pressure medium from both chambers 401, 402 of the pressure medium reservoir 4 can be avoided even when switched off and without consuming electrical energy.

The normally closed connection valves 26a, 26b thus represent the functions of connecting the first and second brake circuits I, II (or the first brake circuit pressure line section 12a and the second brake circuit pressure line section 12b) for primary braking by means of the first pressure supply device 5 and of separating the first and second brake circuits I, II in response to a detected loss of pressure medium. The connection valves 26a, 26b are designed such that the first pressure supply device 5 can open the connection valves 26a, 26b in the direction of pressure build-up (pressure build-up direction of the connection valves, ie from the pressure supply device 5 in the direction of the wheel brakes / brake circuit pressure line sections 12a, 12b) without a function-limiting pressure loss. Whereas the activation valves 26a, 26b in their de-energized state cannot be opened, pushed open, or overflowed by (over)pressure from the second pressure supply device 60 (in the pressure reduction direction of the activation valve, i.e. from the wheel brakes/brake circuit pressure line section 12a, 12b towards the pressure supply device 5). Thus, the first pressure supply device 5 can actuate all wheel brakes 8-11 even if the activation valves 26a, 26b cannot be opened by energization, e.g. in the event of a failure of the electronic control and regulating unit 210 controlling the activation valves 26a, 26b. Likewise, the second pressure supply device 60 can actuate all wheel brakes 8-11 if the first pressure supply device 5 fails, since the two brake circuits I, II are hydraulically separated from each other and from the first pressure supply device 5 by the connection valves 26a, 26b. Even in the event of a leak in one of the two brake circuits I or II, the wheel brakes of the other brake circuit II or I can be actuated by means of the second pressure supply device 60.

QUOTES CONTAINED IN THE DESCRIPTION

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Cited patent literature

• WO 2020/229484 A1 [0002]

Claims (14)

Brake system for a motor vehicle with • a first electrically controllable pressure supply device (5), • a pressure fluid reservoir (4), • a first brake circuit (I) with a first brake circuit pressure line section (12a) for connection to first wheel brakes (8, 9) and a second brake circuit (II) with a second brake circuit pressure line section (12b) for connection to second wheel brakes (10, 11), wherein the first pressure supply device (5) is hydraulically connected to the first brake circuit pressure line section (12a) via an electrically actuated first connection valve (26a) and is hydraulically connected to the second brake circuit pressure line section (12a, 12b) via an electrically actuated second connection valve (26b), • an inlet valve (6a-6d), and in particular an outlet valve (7a-7d), for each first and second wheel brake (8, 9, 10, 11), wherein the input connections of the inlet valves (6a, 6b) of the first wheel brakes (8, 9) are connected to the first brake circuit pressure line section (12a) and the input connections of the inlet valves (6c, 6d) of the second wheel brakes (10, 11) are connected to the second brake circuit pressure line section (12b), and • a second electrically controllable pressure supply device (60) with a pump (60a, 60b) for each brake circuit (I, II), the pressure side (160a, 160b) of which is connected to the inlet valves of the wheel brakes assigned to the brake circuit, characterized in that the suction sides (161a, 161b) of the pumps (60a, 60b) are hydraulically connected to one another and are connected to the pressure medium reservoir (4) via an electrically actuatable isolating valve (23). Brake system after Claim 1 , characterized in that in the hydraulic connection between the suction sides of the pumps (60a, 60b) and the pressure medium reservoir (4) no further electrically actuated valve is arranged besides the isolating valve (23). Brake system after Claim 1 or 2 , characterized in that the first and the second connection valve (26a, 26b) are closed when de-energized and are designed such that the first pressure supply device (5) can open them in their de-energized state by a pressure build-up. Brake system according to one of the preceding claims, characterized in that in the hydraulic connection between the first pressure supply device (5) and the inlet valves (6a, 6b) of the first wheel brakes (8, 9) no further electrically actuated valve is arranged besides the first connection valve (26a), and in that in the hydraulic connection between the first pressure supply device (5) and the inlet valves (6c, 6d) of the second wheel brakes (10, 11) no further electrically actuated valve is arranged besides the second connection valve (26b). Brake system according to one of the preceding claims, characterized in that it has an outlet valve (7a-7d) for each first and second wheel brake (8, 9, 10, 11) and the outlet valves (7a-7d) are hydraulically connected to the pressure medium reservoir (4) via the isolating valve (23). Brake system according to one of the preceding claims, characterized in that the first pressure supply device (5) and the isolating valve (23) are controlled by a first electronic control and regulating unit (110) and that the first and second connection valves (26a, 26b), the second pressure supply device (60) and the inlet valves (6a-6d), and in particular the outlet valves (7a-7d), are controlled by a second electronic control and regulating unit (210) which is independent of the first electronic control and regulating unit (110). Brake system according to one of the preceding claims, characterized in that the first pressure supply device (5) is hydraulically connected to the pressure medium reservoir (4) via a suction valve (53), in particular via a check valve (53) opening in the direction of the first pressure supply device (5), wherein the suction valve (53) is connected to a first chamber (401) of the pressure medium reservoir (4) and the isolating valve (23) is connected to a second chamber (402) of the pressure medium reservoir (4). Brake system according to one of the preceding claims, characterized in that an electrically actuated, in particular normally open, pressure control valve (61a, 61b) is connected in parallel to each pump (60a, 60b). Brake system after Claim 8 , characterized in that the pressure control valves (61a, 61b) connected in parallel to the pumps (60a, 60b) are controlled by the same electronic control and regulating unit (210) as the second pressure supply device (60). Brake system according to one of the preceding claims, characterized in that the first pressure supply device (5) and the isolating valve (23) is arranged in a first independent module (100) and that the first and second connection valves (26a, 26b), the second pressure supply device (60) and the inlet valves (6a-6d), and in particular the outlet valves (7a-7d), are arranged in a second independent module (200). Method for operating a braking system according to one of the Claims 1 until 10 , characterized in that in a predetermined situation of the braking system, in particular by means of the first electronic control and regulating unit (110), the isolating valve (23) is closed and the first pressure supply device (5) is controlled in such a way that the currentless first and the currentless second connection valve (26a, 26b) are opened. Procedure according to Claim 11 , characterized in that a pressure reduction is carried out by opening the isolating valve (23), in particular by means of the first electronic control and regulating unit (110). Method for operating a braking system according to one of the Claims 1 until 10 , especially after one of the Claims 11 or 12 , characterized in that if a loss of pressure medium is detected, the integrity of the hydraulic connection between the second pressure supply device (60) and the isolating valve (23) is checked. Procedure according to Claim 13 , characterized in that , when the integrity of the hydraulic connection has been confirmed, the second pressure supply device (60) is controlled to build up a pressure.

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