DE102020212631A1 - Brake system for motor vehicles - Google Patents

Abstract

Brake system for a motor vehicle with a brake pedal-operated master brake cylinder (2), a first electrically controllable pressure supply device (5) with a pressure chamber (37), a pressure medium reservoir (4) under atmospheric pressure, and an electrohydraulic wheel pressure supply module (200) for connection to first wheel brakes (8th , 9) of a first brake circuit (I) and for connection to second wheel brakes (10, 11) of a second brake circuit (II) which has an inlet valve (6a-6d) and an outlet valve (7a-7d) for each first and second wheel brake ( 8, 9, 10, 11), wherein the input ports of the intake valves (6a, 6b) of the first wheel brakes (8, 9) are hydraulically connected to a first brake circuit pressure line section (12a) and the input ports of the intake valves (6c, 6d) to the second Wheel brakes (10, 11) are hydraulically connected to a second brake circuit pressure line section (12b), the master brake cylinder (2) being connected to the first and the two th brake circuit pressure line section (12a, 12b) is separably hydraulically connected and the pressure chamber (37) of the first pressure supply device (5) via a first electrically actuable switching valve (26a) to the first brake circuit pressure line section (12a) and via a second electrically actuatable switching valve (26b). is hydraulically connected to the second brake circuit pressure line section (12b), the pressure chamber (37) of the first pressure supply device (5) being hydraulically connected to the pressure medium reservoir (4) via an electrically actuable pressure reduction valve (52).

Description

The invention relates to a brake system according to the preamble of claim 1.

From the DE 10 2012 205 860 A1 a "brake-by-wire" brake system for motor vehicles is known, which comprises a first electrohydraulic module and a second electrohydraulic module, the second module being connected downstream of the first module. The first module includes, among other things, a brake pedal-operated tandem master brake cylinder with downstream isolating valves, a travel simulator interacting with the tandem master brake cylinder, and a first electrically controllable pressure source with downstream connection valves. A pressure medium reservoir is assigned to the first module. The second module includes, among other things, an inlet valve and an outlet valve for each wheel brake that can be connected, a second electrically controllable pressure supply device in the form of a pump for each brake circuit and a low-pressure accumulator for each brake circuit. A suction line, which is connected to the pressure medium reservoir, leads to the pressure chamber of the first pressure source via a check valve that opens in this flow direction.

It is the object of the present invention to provide an improved, compact brake system which is suitable for highly automated driving and can be arranged flexibly in the motor vehicle. It should also be possible to drain excess volume of pressure medium into the pressure medium reservoir at any time.

According to the invention, this object is achieved by a brake system according to claim 1 .

The invention is based on a brake system with a master brake cylinder that can be actuated by a brake pedal, a first electrically controllable pressure supply device with a pressure chamber, a pressure medium reservoir under atmospheric pressure, and an electrohydraulic wheel pressure supply module for connection to first wheel brakes of a first brake circuit and for connection to second wheel brakes of a second brake circuit, which Inlet valve and one outlet valve for each first and second wheel brake, with the inlet connections of the inlet valves of the first wheel brakes being connected to a first brake circuit pressure line section and the inlet connections of the inlet valves of the second wheel brakes being connected with a second brake circuit pressure line section, with the master brake cylinder being connected to the first and the second brake circuit pressure line section is separably connected and the pressure chamber of the first pressure supply device via a first el an electrically actuable switching valve is connected to the first brake circuit pressure line section and via a second electrically actuatable switching valve to the second brake circuit pressure line section (12b). The pressure chamber of the first pressure supply device is hydraulically connected to the pressure medium reservoir via an electrically actuable pressure reduction valve. Additional or excess pressure medium volume, which was sucked in from the pressure medium reservoir by the second pressure supply device, for example, can be reduced for both brake circuits by opening the pressure reduction valve in the pressure medium reservoir.

The electrohydraulic wheel pressure supply module preferably includes a low-pressure accumulator for each brake circuit. The low-pressure accumulator for each brake circuit is particularly preferably connected to the outlet connections of the outlet valves assigned to the brake circuit.

The electrohydraulic wheel pressure supply module preferably includes a second electrically controllable pressure supply device, which can build up pressure on the wheel brakes in the event of a fault in the first electrically controllable pressure supply device.

The second electrically controllable pressure supply device preferably includes a pump for each brake circuit, the suction side of which is connected to the brake circuit pressure line section and the low-pressure accumulator of the brake circuit, and the pressure side of which is connected to the inlet valves of the wheel brakes assigned to the brake circuit.

It is preferably a brake system that can be controlled in a brake-by-wire mode both by the vehicle driver and independently of the vehicle driver, is normally operated in the brake-by-wire mode and can be operated in a hydraulic fallback mode.

The electrically actuable pressure reduction valve is preferably designed to be closed when de-energized. In this way, the energy consumption of the braking system can be reduced.

In addition to the pressure reduction valve, no further valve is preferably arranged in the hydraulic connection between the pressure chamber of the first pressure supply device and the pressure medium reservoir. This prevents additional throttling losses during pressure reduction and ensures that the pressure is reduced as quickly as possible.

The first sequence valve and the second sequence valve are preferably via a system pressure line Device connected to each other, which is connected to the pressure chamber of the first pressure supply device, wherein the system pressure line is connected to the pressure medium reservoir via the pressure reduction valve and a drain line. This is advantageous since the pressure chamber then requires only one connection, namely for connection to the system pressure line. A more compact design is thus possible when the first pressure supply device is integrated into an electrohydraulic module, in particular into an independent, electrohydraulic pressure supply module. Furthermore, simpler bores are possible in the module of the first pressure supply device.

Alternatively, it is preferred that the pressure chamber of the first pressure supply device is connected to the pressure medium reservoir via a discharge line between the pressure chamber and the pressure medium reservoir, with the pressure reduction valve being arranged in the discharge line. The pressure chamber then comprises two connections, one for connecting to the sequence valves or the system pressure line and one for connecting to the drain line.

The system pressure line is preferably connected directly to the pressure medium reservoir via the pressure reduction valve and the drain line. Particularly preferably, no further valve is arranged in the drain line between the system pressure line and the pressure medium reservoir next to the pressure reduction valve. This prevents additional throttling losses during pressure reduction and ensures that the pressure is reduced as quickly as possible.

According to a preferred development of the invention, the master brake cylinder is arranged in an independent, electrohydraulic actuating module and the first electrically controllable pressure supply device and the pressure reduction valve in an independent, electrohydraulic pressure supply module, with the pressure medium reservoir being arranged on the pressure supply module. In this way, the pressure supply module can be arranged in the vehicle independently of the actuating module, which must be arranged on the bulkhead due to the connection to the brake pedal. Any vibrations when the first pressure supply device or a valve of the pressure supply module is actuated are thus transmitted to the bulkhead or the driver to a lesser extent. The pressure medium reservoir ensures the direct supply of the first pressure supply device with pressure medium in the brake-by-wire operating mode.

A second pressure medium reservoir is preferably arranged on the actuating module. This offers the advantage that the master brake cylinder is supplied with pressure medium via a short hydraulic line with low flow resistance. A long hydraulic line from the actuating module with the master brake cylinder to the pressure medium reservoir, which is arranged on the pressure supply module, can also be omitted.

The pressure medium reservoir of the pressure supply module and the second pressure medium reservoir of the actuating module are preferably connected to a third pressure medium reservoir. The third pressure medium reservoir can be installed at a different location in the vehicle and serves to provide additional pressure medium for both the pressure medium reservoir of the pressure supply module and the second pressure medium reservoir of the actuation module. The pressure medium reservoir of the pressure supply module and the second pressure medium reservoir of the actuation module can be dimensioned smaller. This offers the advantage that, despite the second pressure medium reservoir, the actuating module to be attached to the bulkhead is small in size.

A simulation device that is operatively connected to the master brake cylinder is preferably arranged in the actuating module and conveys a brake pedal feel to the driver, e.g. in the brake-by-wire operating mode. The simulation device is particularly preferably designed to be switched on and off by means of a simulator valve. The simulator valve is advantageously arranged in the actuation module. The simulator valve is particularly preferably activated by a (second) electronic control and regulation unit assigned to the activation module.

The master brake cylinder is preferably connected to the first brake circuit pressure line section via a first electrically actuatable separating valve and to the second brake circuit pressure line section via a second electrically operable separating valve, the first separating valve and the second separating valve being arranged in the pressure supply module. The isolating and connecting valves for selectively connecting the two brake circuit pressure line sections, and thus the wheel brakes, to the master brake cylinder (backup mode) or the first pressure supply device (brake-by-wire mode) are preferably arranged in the pressure supply module. These valves are advantageously activated by the (first) electronic control and regulation unit assigned to the pressure supply module.

A first pressure sensor in the wheel pressure supply module and a wide one are preferred rer pressure sensor provided in the pressure supply module, which detect a pressure of the first pressure supply device. The pressure value of the first pressure supply device can be processed using the first pressure sensor without latency times in the (second) electronic control and regulation units assigned to the wheel pressure supply module, while the pressure value of the first pressure supply device can be processed using the additional pressure sensor without latency times in the (first) electronic unit assigned to the pressure supply module Control and regulation units can be processed.

A first pressure sensor is preferably provided in the wheel pressure supply module and a further pressure sensor, particularly preferably in the pressure supply module, is provided, with the first pressure sensor detecting a pressure prevailing in one of the brake circuit pressure line sections and the further pressure sensor detecting a pressure prevailing in the same brake circuit pressure line section.

Alternatively, it is preferable for a first pressure sensor to be provided in the wheel pressure supply module and a further pressure sensor, particularly preferably in the pressure supply module, with the first pressure sensor detecting a pressure prevailing in one of the brake circuit pressure line sections and the further pressure sensor detecting a pressure prevailing in the other brake circuit pressure line section . Advantageously, the first pressure sensor and the additional pressure sensor detect a pressure prevailing in the second brake circuit pressure line section.

A first pressure sensor is preferably provided in the wheel pressure supply module, which detects a pressure prevailing in one of the brake circuit pressure line sections, and a second pressure sensor is provided in the pressure supply module. The second pressure sensor detects a pressure prevailing in the system pressure line. For example, the first pressure sensor in the wheel pressure supply module detects the pressure prevailing in the second brake circuit pressure line section. The arrangement of the second pressure sensor in direct hydraulic connection with the first pressure supply device has the advantage of the greatest symmetry. This makes it easier to check the sequence valves for leaks.

According to a preferred embodiment of the brake system, the pressure supply module and the wheel pressure supply module each have their own electronic control and regulation unit. This advantageously ensures independent activation of the first and second electrically controllable pressure supply devices.

According to a preferred embodiment of the brake system, the actuation module also has its own electronic control and regulation unit. This is particularly preferably designed to control a simulator valve arranged in the actuation module and/or to connect to a sensor assigned to the master brake cylinder, in particular a displacement sensor for detecting a displacement or position of a piston of the master brake cylinder.

The pressure supply module and the wheel pressure supply module are preferably hydraulically connected to one another exclusively via the brake circuit pressure line sections.

A hydraulic connection between the respective brake circuit pressure line section and the pressure medium reservoir is preferably provided for the first and for the second brake circuit pressure line section, in which connection a check valve opening in the direction of the brake circuit pressure line section is arranged. This offers the advantage that the second pressure supply device can draw in an additional volume of pressure medium from the pressure medium reservoir.

The first pressure supply device is preferably designed as a cylinder-piston arrangement with a hydraulic pressure chamber, the piston of which can be advanced and retracted by an electromechanical actuator. The size of the pressure chamber of the pressure supply device, and thus the maximum pressure medium volume that can be grasped, is particularly preferably designed such that the first pressure supply device can provide a maximum locking pressure of the wheel brakes. In this way, the installation space of the pressure supply module can be reduced.

The master brake cylinder particularly preferably comprises two pressure chambers which are separated from one another by a floating piston, the first pressure chamber being connected to the first brake circuit pressure line section via the first electrically actuatable isolating valve and the second pressure chamber being connected to the second brake circuit pressure line section via the second electrically actuatable isolating valve. The dual circuit offers the advantage of greater availability of the brake system in the event of a leak. In the event of a leak, the sequence valves and isolating valves can isolate the affected area/hydraulic component and the rest of the brake system is still able to build up pressure and partially activate the wheel brakes.

The second pressure supply device is preferably formed by two pumps which are driven jointly by an electric motor.

For each brake circuit, the inlet valves are preferably connected to the brake circuit pressure line section via an analogously controllable, normally open valve. This valve makes it possible, for example, to separate the brake circuit pressure line section from the wheel brakes, e.g. in the event of a pressure build-up by means of the second pressure supply device. A non-return valve opening in the direction of flow to the inlet valves is particularly preferably connected in parallel with the normally open valve. The analog controllable, normally open valves are particularly preferably arranged in the wheel pressure supply module.

For each brake circuit, the suction side of the second pressure supply device, in particular the pump, is preferably connected to the brake circuit pressure line section via an electrically actuable pressure medium supply valve. This pressure medium supply valve allows pressure medium to be sucked in by the pump from the low-pressure accumulator or from the brake circuit pressure line section, which is connected to the pressure medium reservoir via a check valve. The pressure medium supply valves are particularly preferably arranged in the wheel pressure supply module.

Preferably, at least the pressure supply module and the wheel pressure supply module are each designed as an electrohydraulic control and regulation unit (HECU: Hydraulic Control Unit) with a valve block (HCU: Hydraulic Control Unit) and an electronic control and regulation unit (ECU: Electronic Control Unit). The actuating module is also preferably designed as an electrohydraulic control and regulation unit (HECU: Hydraulic Control Unit) with a valve block (HCU: Hydraulic Control Unit) and an electronic control and regulation unit (ECU: Electronic Control Unit).

Further preferred embodiments of the invention result from the claims and the following description based on figures.

• 1 ein erstes Ausführungsbeispiel einer erfindungsgemäßen Bremsanlage, und
• 2 weitere Ausführungsbeispiele einer erfindungsgemäßen Bremsanlage.

They show schematically:

• 1 a first embodiment of a brake system according to the invention, and
• 2 further exemplary embodiments of a brake system according to the invention.

In 1 is a first embodiment of a brake system according to the invention shown schematically.

The brake system includes, for example, a first independent electrohydraulic module 100 (pressure supply module), a second independent electrohydraulic module 200 (wheel pressure supply module) and a third independent electrohydraulic module 300 (actuation module or pedal actuation unit).

Each of the three modules 100, 200, 300 is, for example, an electrohydraulic control and regulation unit (HECU: Hydraulic Control Unit) with a valve block (HCU: Hydraulic Control Unit) and an electronic control and regulation unit (ECU: Electronic Control Unit) educated.

The brake system comprises a master brake cylinder 2 that can be actuated by means of an actuating or brake pedal 1 and a simulation device 3, which are arranged in the third independent module 300, a first electrically controllable pressure supply device 5, which is arranged in the first independent module 100, and for each Wheel brake 8-11 an inlet valve 6a-6d and an outlet valve 7a-7d and a second electrically controllable pressure supply device 60. The inlet valves 6a-6d, the outlet valves 7a-7d and the second pressure supply device 60 are arranged in the second independent module 200.

A pressure medium reservoir 4 under atmospheric pressure is arranged on the first independent module 100 .

In addition to the pressure medium reservoir 4 arranged on the first module 100 , a second pressure medium reservoir 304 is provided, which is arranged on the third module 300 . This means that each of the modules 100 or 300 is assigned its own pressure medium reservoir 4 or 304, which is arranged on the respective module 100 or 300.

Furthermore, a pressure medium reservoir 104 is provided, which supplies the pressure medium reservoirs 4 and 304 with pressure medium. Pressure medium reservoir 104 can be arranged separately.

The hydraulic system of wheel pressure supply module 200 has a two-circuit design, with the (first) wheel brakes 8, 9 being assigned to a first brake circuit I with a first brake circuit pressure line section 12a and the (second) wheel brakes 10, 11 being assigned to a second brake circuit II with a second brake circuit pressure line section 12b.

Master brake cylinder 2 is connected to the first and the second brake circuit pressure line section 12a, 12b. The first pressure supply device 5 is also connected to the first and the second Brake circuit pressure line section 12a, 12b connected.

Master brake cylinder 2 has, for example, two pistons 15, 16 arranged one behind the other, which delimit two hydraulic pressure chambers 17, 18. The pressure chambers 17, 18 are connected to the pressure medium reservoir 304 via radial bores formed in the pistons 15, 16 and corresponding pressure compensation lines 41a, 41b, the connections being able to be shut off by a relative movement of the pistons 15, 16. On the other hand, pressure chamber 17 is connected to brake circuit pressure line section 12a by means of a hydraulic line section 22a, and pressure chamber 18 is connected to brake circuit pressure line section 12b by means of a hydraulic line section 22b.

The pressure chambers 17, 18 accommodate unspecified restoring springs, which position the pistons 15, 16 in a starting position when the master brake cylinder 2 is not actuated. A piston rod 24 couples the pivoting movement of the brake pedal 1 as a result of pedal actuation with the translational movement of the first (brake master cylinder) piston 15, the actuation path of which is detected by a displacement sensor 25, preferably of redundant design. As a result, the corresponding piston travel signal is a measure of the brake pedal actuation angle. It represents a driver's braking request.

A parallel connection of a throttle element 28 with a check valve 27 closing towards the pressure medium reservoir 304 is contained in the pressure compensation line 41a.

Simulation device 3 is designed, for example, as a hydraulic simulator unit (within first module 300), which can be hydraulically coupled to master brake cylinder 2. Other versions of the simulation device or other connections of the simulation device to the master brake cylinder 2 are conceivable. Thus, simulation device 3 could also be designed as a simulator spring arranged, for example, in the master brake cylinder.

According to the example, simulation device 3 consists essentially of a simulator chamber 29, a simulator spring chamber 30 and a simulator piston 31 separating the two chambers 29, 30 from one another. The simulator piston 31 is supported by an elastic element (e.g. a spring) arranged in the simulator spring chamber 30, which is advantageously prestressed is, on the housing (valve block). The simulator chamber 29 can be connected to the pressure chamber 17 of the master brake cylinder 2 by means of an electrically actuable simulator valve 32 . When a pedal movement is specified and the simulator valve 32 is open, pressure medium flows from the master brake cylinder pressure chamber 17 into the simulator chamber 29. A check valve 34, which is arranged hydraulically antiparallel to the simulator valve 32, enables the pressure medium to flow back largely unhindered from the simulator chamber 29 to the master brake cylinder pressure chamber, regardless of the switching state of the simulator valve 32 17

The hydraulic components check valve 27, throttle element 28, which are associated with the master brake cylinder 2, the simulator valve 32 and check valve 34 associated with the simulation device 3, and the master brake cylinder travel sensor 25 are arranged in the actuation module 300. Module 300 includes a (third) electronic control and regulation unit (ECU) 310 for controlling the electrically actuable components of the module.

For each brake circuit I, II, a separating valve 23a or 23b is connected between the hydraulic line section 22a or 22b and the brake circuit pressure line section 12a or 12b. The isolating valves 23a, 23b are designed as electrically actuated valves, preferably normally open valves, e.g. 2/2-way valves. The hydraulic connection between the master brake cylinder 2 and the brake circuit pressure line sections 12a, 12b can be shut off by the isolating valves 23a, 23b.

The electrically controllable pressure supply device 5 is formed as a hydraulic cylinder-piston arrangement with a hydraulic pressure chamber 37, the piston 36 of which can be moved back and forth by an electromechanical actuator. Pressure supply device 5 thus represents a single-circuit electrohydraulic actuator whose piston 36, which delimits the pressure chamber 37, can be moved back and forth by a schematically indicated electric motor 35 with the interposition of a rotation-translation gear, also shown schematically. A rotor position sensor which is indicated schematically and is used to detect the rotor position of the electric motor 35 is denoted by the reference number 44 .

Pressure chamber 37 is hydraulically connected via a system pressure line 38 to a first switching valve 26a and a second switching valve 26b, the first switching valve 26a being hydraulically connected to the brake circuit pressure line section 12a on the wheel brake side and the second switching valve 26b being hydraulically connected to the brake circuit pressure line section 12b on the wheel brake side. Thus, the pressure supply device 5 or its pressure chamber 37 can be separated from the two brake circuit pressures line sections 12a, 12b and thus the brake circuits I, II and their wheel brakes 8, 9, 10, 11 connected.

The sequence valves 26a, 26b are advantageously designed as electrically actuated valves, preferably normally closed valves, e.g. 2/2-way valves. When the sequence valves 26a, 26b are open, when the piston 36 is displaced in the brake actuation direction, pressure medium flows from the pressure chamber 37 into the brake circuit pressure line sections 12a, 12b, and thus into the wheel pressure supply module (second module) 200, and thus into the wheel brakes 8, 9, 10, 11 for their operation.

For each brake circuit I, II, the brake circuit pressure line section 12a or 12b is connected to the pressure medium reservoir 4 via a hydraulic connection section 40a or 40b, with a check valve 53a or 53b opening in the direction of the brake circuit pressure line section being arranged between the brake circuit pressure line section and the connection section.

The check valves 53a, 53b are arranged in the first independent module 100. The hydraulic connection sections 40a, 40b are also arranged in the first stand-alone module 100. FIG.

The system pressure line 38 is hydraulically connected to the pressure medium reservoir 4 via a drain line 54, an electrically actuable pressure reduction valve 52 being arranged between the system pressure line and the drain line. The pressure reduction valve 52 is advantageously designed to be closed when de-energized.

According to the example, the connecting section 40b opens into the drain line 54.

A preferably redundant pressure sensor 21 is provided for detecting the master brake cylinder pressure, which is connected to one of the pressure chambers of the master brake cylinder 2, for example to the pressure chamber 17.

For each brake circuit I, II, the output connections of the isolating valve 23a or 23b and the connecting valve 26a or 26b are connected to the associated brake circuit pressure line sections 12a or 12b. Correspondingly, master brake cylinder 2 is connected to the first brake circuit pressure line section 12a (via isolating valve 23a) and to the second brake circuit pressure line section 12b (via isolating valve 23b). Likewise, pressure supply device 5 is connected to the first brake circuit pressure line section 12a (via switching valve 26a) and to the second brake circuit pressure line section 12b (via switching valve 26b).

The first pressure supply device 5, the isolating valves 23a, 23b, the connecting valves 26a, 26b, the check valves 53a, 53b and the pressure reduction valve 52 are arranged in the first independent module 100. According to the example, the system pressure line 38, the connecting sections 40a, 40b, the drain line 54 and the pressure sensor 21 are also arranged in the first independent module 100.

The first module (pressure supply module) 100 is connected to the second module (wheel pressure supply module) 200 via the brake circuit pressure line sections 12a, 12b. The third module (actuating module) 300 is connected to the first module (pressure supply module) 100 via the line sections 22a, 22b.

Correspondingly, parts of the brake circuit pressure line sections 12a, 12b and parts of the line sections 22a, 22b are arranged in the first module 100.

Other parts of the brake circuit pressure line sections 12a, 12b are arranged in the second module 200. Other parts of the line sections 22a, 22b are arranged in the third module 300. FIG.

To control the electrically actuable components of module 100, module 100 includes a (first) electronic control unit (ECU) 110.

As already mentioned, the inlet and outlet valves 6a-6d, 7a-7d and the second pressure supply device 60 are part of the second module 200 (wheel pressure supply module). This is designed, for example, as a known ESC module (ESC: Electronic Stability Control), which will be described in more detail below.

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 or 6c, 6d of a brake circuit I or II are connected via a so-called modulator admission pressure line and an analog controllable, normally open valve 61a or 61b, to which a check valve 64a or 64b opening in the direction of flow to the wheel brakes is connected in parallel with the associated brake circuit pressure line section 12a or 12b. The intake valves 6a-6d each have a modula check valve 50a-50d connected in parallel to the gate admission pressure lines.

The output connections of the outlet valves 7a, 7b or 7c, 7d of a brake circuit I or II are connected to a hydraulic low-pressure accumulator 65a, 65b (for each brake circuit).

The second pressure supply device 60 includes two pumps 60a, 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. The pressure side of the pump 60a or 60b is connected to the corresponding modulator admission pressure line and thus to the inlet valves of the corresponding brake circuit. The suction side of the pump 60a or 60b is connected on the one hand to the corresponding low-pressure accumulator 65a or 65b of brake circuit I or II via a check valve 63a or 63b closing in the direction of the low-pressure accumulator.

On the other hand, the suction side of the pump 60a or 60b is connected to the corresponding brake circuit pressure line section 12a or 12b via an electrically actuable pressure medium supply valve 62a or 62b, which is advantageously closed when de-energized. The pressure medium volume required for pressure build-up by means of pumps 60a, 60b can be supplied to each brake circuit I or II via pressure medium supply valve 62a or 62b, brake circuit pressure line section 12a or 12b and check valve 53a or 53b (connecting section 40a or 40b). .

To detect the pressure prevailing in the brake circuit pressure line section 12b, and thus the pressure of the first pressure supply device 5 in the brake-by-wire operating mode, a preferably redundantly designed pressure sensor 20 is provided, which is part of the module 200.

The inlet and outlet valves 6a-6d, 7a-7d, the low-pressure accumulator 65a, 65b and the second pressure supply device 60 (60a, 60b) are arranged in the second independent module 200, the so-called wheel pressure supply module. The hydraulic components check valves 50a-50d, 63a, 63b, 64a, 64b, valves 61a, 62a, 61b, 62b and the pressure sensor 20 are also arranged in module 200.

To control the electrically actuable components of module 200, module 200 includes a (second) electronic control unit (ECU) 210.

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, in particular the signals from the pressure sensor 20.

Within module 100, for each brake circuit I (or II), the output connections of the isolating valve 23a (or 23b) and the connecting valve 26a (or 26b) are connected to one another via the brake circuit pressure line section 12a (or 12b), which is the hydraulic connection already mentioned of the two modules 100 and 200 by only two hydraulic flow paths.

According to another preferred embodiment, the brake system can 1 also include only one, under atmospheric pressure, arranged on the first independent module 100 pressure medium reservoir 4. The pressure chambers 17, 18 of the master brake cylinder 2 are then each connected hydraulically via a pressure compensation line to the pressure medium reservoir 4 arranged on the first independent module 100.

In 2 further exemplary embodiments of a brake system according to the invention are shown schematically. The braking system includes those associated with the braking system of 1 described components. In addition, at least one further pressure sensor is provided, which is part of the first module 100. This further pressure sensor can be connected to the second brake circuit II within the first module 100, in particular to the line section between the connection valve 26b and the isolating valve 61b in the first module 100. This corresponds to the pressure sensor 120 shown. According to an alternative exemplary embodiment, the further pressure sensor can be connected to the system pressure line 38, ie to the line section between the connection valve 26b, pressure chamber 37, connection valve 26a and drain valve 52 within the first module 100. This corresponds to the pressure sensor 121 shown in dashed lines.

As a disadvantage in the embodiment of 1 it can be seen that the value of the pressure of the first pressure supply device 5 has to be obtained from the second module with pressure sensor 20 via a data bus (vehicle bus), which leads to latency times and a lower clock rate.

Therefore, according to the embodiments of 2 the value of the pressure of the first pressure supply device 5 is measured in the module 100 of the first pressure supply device 5 . For this purpose, an additional pressure sensor 120 or 121 is provided in the module 100, which is connected to the system pressure line 38 (pressure sensor 121) or to the brake circuit pressure line section 12b (pressure sensor 120).

The described arrangement of the components of the exemplary brake systems in three modules 100, 200, 300 offers the advantage that only module 300, the so-called pedal actuation unit, has to be accommodated on the bulkhead. The modules 100 and 200 can be located elsewhere in the vehicle or under the hood.

In the hydraulic fallback mode (e.g. in the de-energized state of the brake system), the brake systems in the example have a completely dual-circuit structure.

In the brake systems according to the example, a pressure supply device 5 with the smallest possible volume should be used for reasons of installation space. If there is a high volume requirement, e.g. when the wheel brakes 8-11 are hot, the second pressure supply device 60 delivers an additional volume of pressure medium into the wheel brakes 8-11 via the check valves 53a, 53b of the module 100 assigned to it. If the discharge line 54 with the pressure reduction valve 52 were not present, this volume of pressure medium could only be reduced back into the pressure medium reservoir 4 after the brake pedal 1 had been released. This disadvantage could also only be partially compensated for by charging the low-pressure accumulators 65a, 65b of the second module (wheel pressure supply module) 200. According to the invention, an (additional) electrically actuable pressure reduction valve 52 is therefore provided in module 100 . The pressure reduction valve 52 connects the pressure chamber of the first pressure supply device 5 or the system pressure line 38 to the pressure medium reservoir 4.

The pressure reduction valve 52 is preferably closed when de-energized. This has the advantage of reduced energy consumption.

With an active pressure build-up by wheel pressure supply module 200, the example brake systems allow pressure medium to be sucked in by pressure supply device 60 from pressure medium reservoir 4 via check valves 53a, 53b (and valves 62a, 62b).

In the brake systems according to the example, it is easily possible to connect the system pressure area, advantageously the system pressure line 38, via the drain valve 52 directly to the pressure medium reservoir 4 and thus drain excess pressure medium volume into it.

By hydraulically connecting the system pressure line 38 to the pressure medium reservoir 4 by opening the drain valve 52, in the brake-by-wire operating mode (i.e. when the switching valves 26a, 26b are open) pressure medium volume can flow uniformly from both brake circuit pressure line sections 12a, 12b at the same pressure into the pressure medium reservoir 4 be drained.
Thus, via the drain line 54 with the drain valve 52, excess pressure medium is reduced immediately and in the same way for both brake circuits I, II.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102012205860 A1 [0002]

Claims (13)

Brake system for a motor vehicle with • a master brake cylinder (2) that can be actuated by a brake pedal, • a first electrically controllable pressure supply device (5) with a pressure chamber (37), • a pressure medium reservoir (4) at atmospheric pressure, and • an electrohydraulic wheel pressure supply module (200) for connection to first wheel brakes (8, 9) of a first brake circuit (I) and for connection to second wheel brakes (10, 11) of a second brake circuit (II), which has an inlet (6a-6d) and an outlet valve (7a-7d) each first and second wheel brake (8, 9, 10, 11), wherein the inlet ports of the inlet valves (6a, 6b) of the first wheel brakes (8, 9) are hydraulically connected to a first brake circuit pressure line section (12a) and the inlet ports of the inlet valves (6c, 6d) the second wheel brakes (10, 11) are hydraulically connected to a second brake circuit pressure line section (12b), the master brake cylinder (2) being connected to the first and the second brake circuit pressure line section (12a, 12b) is separably hydraulically connected and the pressure chamber (37) of the first pressure supply device (5) via a first electrically actuable switching valve (26a) with the first brake circuit pressure line section (12a) and via a second electrically actuatable switching valve (26b) is hydraulically connected to the second brake circuit pressure line section (12b), characterized in that the pressure chamber (37) of the first pressure supply device (5) is hydraulically connected to the pressure medium reservoir (4) via an electrically actuable pressure reduction valve (52). brake system after claim 1 , characterized in that the electrically operable pressure reduction valve (52) is designed to be closed when de-energized. brake system after claim 1 or 2 , characterized in that in the hydraulic connection between the pressure chamber (37) of the first pressure supply device (5) and the pressure medium reservoir (4) next to the pressure reduction valve (52) no further valve is arranged. Brake system according to one of the preceding claims, characterized in that the first switching valve (26a) and the second switching valve (26b) are hydraulically connected to one another via a system pressure line (38) which is hydraulically connected to the pressure chamber (37) of the first pressure supply device (5). is, wherein the system pressure line (38) via the pressure reduction valve (52) and a drain line (54) with the pressure medium reservoir (4) is hydraulically connected. brake system after claim 4 , characterized in that the system pressure line (38) via the pressure reduction valve (52) and the drain line (54) is hydraulically connected directly to the pressure medium reservoir (4). Brake system according to one of the preceding claims, characterized in that a first pressure sensor (20) is provided in the wheel pressure supply module (200) and a further pressure sensor (120), the first pressure sensor (20) detecting a pressure prevailing in one of the brake circuit pressure line sections (12b). detected, and wherein the further pressure sensor (120) detects a pressure prevailing in the same brake circuit pressure line section (12b) or a pressure prevailing in the other brake circuit pressure line section. Brake system according to one of Claims 1 until 5 , characterized in that the master brake cylinder (2) is arranged in an independent, electrohydraulic actuation module (300) and in that the first electrically controllable pressure supply device (5) and the pressure reduction valve (52) are arranged in an independent, electrohydraulic pressure supply module (100), wherein the pressure medium reservoir (4) is arranged on the pressure supply module (100). brake system after claim 7 , characterized in that in the actuating module (300) with the master cylinder (2) operatively connected simulation device (3) is arranged. brake system after claim 7 or 8th , characterized in that the master brake cylinder (2) is connected to the first brake circuit pressure line section (12a) via a first electrically actuatable separating valve (23a) and to the second brake circuit pressure line section (12b) via a second electrically operable separating valve (23b), the first separating valve (23a) and the second separating valve (23b) are arranged in the pressure supply module (100). Brake system according to one of Claims 7 until 9 , characterized in that a second pressure medium reservoir (304) is arranged on the actuating module (300). brake system after claim 10 , characterized in that the pressure medium reservoir (4) of the pressure supply module (100) and the second pressure medium reservoir (304) of the actuating module (300) are connected to a third pressure medium reservoir (104). Brake system according to one of Claims 7 until 11 , if referred back to claim 4 , characterized in that a first pressure sensor (20) is provided in the wheel pressure supply module (200), which detects a pressure prevailing in one of the brake circuit pressure line sections (12b), and a second pressure sensor (121) is provided in the pressure supply module (100), which detects a pressure prevailing in the system pressure line (38). Brake system according to one of Claims 7 until 11 , characterized in that a first pressure sensor (20) is provided in the wheel pressure supply module (200) and a further pressure sensor (120) in the pressure supply module (100), the first pressure sensor (20) detecting a pressure prevailing in one of the brake circuit pressure line sections (12b). detected, and wherein the further pressure sensor (120) detects a pressure prevailing in the same brake circuit pressure line section (12b) or a pressure prevailing in the other brake circuit pressure line section.

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