DE102017222435A1 - Brake system for a motor vehicle and method for its operation - Google Patents

Abstract

Brake system for a motor vehicle with at least four hydraulically actuated wheel brakes (8a-8d), a simulation device (3), an electrically actuated inlet valve (6a-6d) per wheel brake (8a-8d), a first electrically controllable pressure supply device (5) via a separating valve (26) is hydraulically connected separably to a brake supply line (13) to which the wheel brakes (8a-8d) are connected, and a second electrically controllable pressure supply means (2) which is hydraulically connected to the brake supply line (13) in the brake supply line (13) an electrically operable Kreistrennventil (40) is arranged such that when the closed Kreistrennventil the brake supply line (13) in a first and a second line section (13 a, 13 b) is hydraulically separated, wherein the first line section (13 a) two of the inlet valves (6a, 6b) is hydraulically connected and the second line section (13b) is hydraulically connected to the other inlet valves (6c, 6d), and wherein the second pressure supply device (2) is hydraulically connected to the first line section (13a) and the first pressure supply device (5) via the separating valve (26) to the second Line section (13b) is hydraulically connected, wherein the second pressure supply device (2) comprises a suction port (23) and a pressure port (27), wherein an overflow valve (32) is provided for adjusting or regulating the pressure provided by the second pressure supply device (2) , via which the pressure port (27) is hydraulically connected to the suction port (23), and to methods for operating such a brake system.

Description

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

From the DE 10 2013 223 859 A1 is a brake system with hydraulically actuated wheel brakes and an actuatable by means of a brake pedal simulation device, with no mechanical and / or hydraulic operative connection between the brake pedal and the wheel brakes is provided. It is a single electrically controllable pressure source provided with a stepped piston and two sealing elements to achieve increased availability of the brake system.

From the DE 10 2013 217 954 A1 is a brake system with two electrically controllable pressure supply device and a Kreistrennventil known, for a purely mechanical / hydraulic fallback a brake pedal-operated master cylinder is present, which is connected to the wheel brakes. A simulation device is hydraulically connected to the master brake cylinder. The pressure-providing devices are both designed as a linear actuator, in which a brake pressure is set by moving a piston back and forth by means of an electric motor with a downstream rotational-translation gear. Should u.ä. in the linear actuator or its control. there is a systematic error or weak point, there is a relatively high risk that both linear actuators could fail at the same time.

It is an object of the present invention to provide a suitable for highly automated driving brake system, which is simple and inexpensive, but which offers the necessary for highly automated driving, the highest possible availability. In particular, should be able to dispense with a brake pedal-operated master cylinder.

This object is achieved by a brake system according to claim 1 and a method according to claim 14 or 15.

The invention is based on the idea to provide a brake system for a motor vehicle with a simulation device, a first electrically controllable pressure supply device, which is hydraulically connected separably via a separating valve with a brake supply line to which the wheel brakes are connected via in each case one of the inlet valves, and a second electrically controllable pressure supply device which is hydraulically connected to the brake supply line, wherein in the brake supply line, an electrically operable Kreistrennventil is arranged such that when the closed Kreistrennventil the brake supply line is hydraulically separated into a first line section and a second line section, wherein the first line section with two of the inlet valves is hydraulically connected and the second line section is hydraulically connected to the other inlet valves, and wherein the second Druckbereitstel the first pressure supply device is hydraulically connected to the second line section via the separating valve, wherein the second pressure supply device comprises a suction port and a pressure port and an overflow valve is provided for setting or regulating the pressure provided by the second pressure supply device, via which the pressure port is hydraulically connected to the suction port. The overflow valve is thus, so to speak, connected in parallel to the second pressure supply device.

The invention has the advantage that even after a serious error, such as a failure of one of the electrically controllable pressure supply devices, the most important braking functions can be performed autonomously or by an autopilot function, in particular to build up delay, to comply with the blocking order of the vehicle axles and to destabilize at high delays prevent and maintain steerability. For this purpose, wheel-individual and at least individual brake circuit-specific pressures are necessary and the setting of respective precise brake pressure curves including pressure build-up, pressure reduction and pressure maintenance. The brake system is thus particularly suitable for the realization of highly automated driving functions. A fallback with a driver-operated master cylinder is therefore not necessary.

The pressure connection of the second pressure supply device is preferably connected to the first line section.

The brake system preferably comprises a pressure medium reservoir, in particular under atmospheric pressure. Particularly preferably, the suction connection of the second pressure supply device is connected to the pressure medium reservoir.

The overflow valve is preferably arranged in a hydraulic connection between the pressure connection of the second pressure supply device or the first line section and the pressure medium reservoir.

In addition to the wheel-brake-specific intake valves, the brake system preferably comprises an electrically actuatable exhaust valve per wheel brake. By means of the exhaust valve, the associated wheel brake is connected to the, in particular under atmospheric pressure, pressure medium reservoir to allow a wheel individual pressure reduction at the wheel by opening the exhaust valve, in particular at a pressure supply by the second pressure supply device. Particularly preferably, the outlet valves are connected via a common hydraulic connection with the pressure medium reservoir. Particularly preferably, the wheel-specific brake pressures are derived from a brake supply pressure in the brake supply line, wherein in an inoperative state the intake valves relay the brake supply pressure to the wheel brakes and the exhaust valves block outflow of pressure fluid from the wheel brakes.

The overflow valve is preferably designed to be de-energized closed in order to prevent a flow of pressure medium via the overflow valve into the pressure medium reservoir, e.g. at a pressure build-up by means of the first pressure supply device to prevent, without a control / switching of the spill valve is necessary. Thus, it is possible to dispense with a further separating valve, via which the second pressure supply device is separably hydraulically connected to the brake supply line or the first line section. The overflow valve is particularly preferably designed to be adjustable analogously in order to ensure a precise pressure position by means of the second pressure supply device, e.g. in case of failure of the first pressure delivery device to allow.

In order to avoid flow resistance, the second pressure supply device is preferably connected directly to the first line section hydraulically. This means that no electrically operable valve is arranged hydraulically between the second pressure supply device or its pressure connection and the first line section. Advantageously, no valve is arranged between the second pressure supply device or its pressure connection and the first line section.

The brake system comprises a simulation device for conveying a brake pedal feeling to a driver. The simulation device is preferably actuated by means of a brake pedal and no mechanical and / or hydraulic operative connection is provided between the brake pedal and the wheel brakes. Particularly preferably, the simulation device comprises a piston which mechanically, e.g. via a push rod connected and coupled to the brake pedal, i. which is directly connected to the brake pedal.

The simulation device is preferably hydraulically connected to none of the wheel brakes. The brake system preferably does not include a brake master cylinder master cylinder which is connected to one of the wheel brakes.

Preferably, the brake system comprises hydraulically actuated wheel brake for four wheels, which are distributed to a first vehicle axle and a second vehicle axle. The wheel brakes connected to the first line section are particularly preferably associated with the first vehicle axle, advantageously the front axle, and the wheel brakes connected to the second line section are assigned to the second vehicle axle, advantageously the rear axle.

Preferably, the second pressure supply device is formed by a piston pump, particularly preferably by a radial piston pump. This long-proven in automotive brake systems and optimized pump type can be used in the brake system, as by means of the spill valve, a pressure relief or pressure reduction can be performed with sufficient speed and precision to provide the above-mentioned main brake functions in case of failure of the first pressure supply device. Piston pumps are inexpensive to produce and are based on known technologies, so that their use also represents a very low development risk for the brake system.

Preferably, the second pressure supply device is formed by a piston pump, while the first pressure supply device is formed by a cylinder-piston arrangement with a hydraulic pressure chamber whose piston is actuated by an electromechanical actuator, wherein the piston for pressure buildup by means of the electromechanical actuator and driven for pressure reduction is returned by the electromechanical actuator. Because first and second pressure providing devices use complementary technology, the risk of simultaneous failure of both pressure delivery devices due to a systematic failure is reduced.

The circular selector valve is preferably designed to be normally open. Thus, all wheel brakes without energizing / switching the circular valve from the first or the second pressure supply device can be pressurized. However, the brake system can, for example in the case of leakage, by closing the circular valve in a first hydraulic brake circuit and a second hydraulic brake circuit are disconnected. The first hydraulic brake circuit comprises the second pressure supply device with the overflow valve, the first line section, as well as two of the wheel brakes with the associated two inlet valves. The second hydraulic brake circuit comprises the first pressure supply device, the isolation valve, the second line section and the other wheel brakes with the associated inlet valves.

Preferably, the pressure fluid level of the pressure medium reservoir is detected by means of a measuring device in order to detect a leak and, if necessary, to perform a circular separation.

The isolation valve is preferably designed to be normally open. Thus, the wheel brakes without energizing / switching the isolation valve can be acted upon by the first pressure supply device with a pressure. In the case of a failure of the first pressure supply device, in particular for preventing a pressure medium volume loss, the first pressure supply device can be separated hydraulically from the brake supply line by closing the separating valve.

The first pressure supply device is preferably formed by a cylinder-piston arrangement with a hydraulic pressure chamber, the piston is actuated by an electromechanical actuator, wherein the pressure chamber is connected in an unactuated state of the piston via at least one Schnüffelloch and a line to the pressure medium reservoir, wherein this connection is disconnected upon actuation of the piston. Such a cylinder-piston arrangement can provide a brake pressure curve by driving the piston back and forth by means of the electromechanical actuator with high dynamics and precision. Particularly preferably, the electromechanical actuator comprises an electric motor with a downstream rotation-translation gear.

Particularly preferably, the first pressure supply device comprises a single pressure chamber, wherein the pressure chamber is connected separable via exactly one separating valve, namely the separating valve, with the brake supply line.

The brake system preferably comprises a first electronic device, by means of which the first pressure supply device is activated, and a second electronic device, by means of which the second pressure supply device is activated. In this case, the second electronic device is electrically independent of the first electronic device, so that an electrical or electronic fault in one of the electronic devices does not lead to failure of both electronic devices.

The two electronic devices are electrically independent of each other in the sense that failure of the first electronic device does not cause failure of the second electronic device, and vice versa, i. the two electronic devices are galvanically isolated.

Preferably, the first electronic device is powered by a first electrical power supply or comprises a first electrical power supply. The second electronic device is powered by a second electrical power supply or comprises a second electrical power supply. In this case, the first electrical energy supply is independent of the second electrical energy supply.

The two electronic devices may be housed in a common housing or on a common circuit board, e.g. in a common electronic control unit (ECU), be arranged. Alternatively, the two electronic devices may be housed in two separate housings or on two separate circuit boards, e.g. in two electronic control units, be arranged.

The first electronic device is designed to actuate or control the first pressure supply device. The first pressure supply device is preferably also supplied with electrical energy by the first electronic device. Accordingly, the second pressure supply device is actuated or activated by means of the second electronic device. Preferably, the second pressure supply device is also supplied by the second electronic device with electrical energy.

The overflow valve and the separating valve are preferably controlled by means of the second electronic device or supplied with electrical energy. Thus, in the event of failure of the first pressure supply device or the first electronic device or the first power supply, a hydraulic separation of the first Druckbereitstellungsseirichtung and a pressure control of the second pressure supply device for the wheel brakes provided brake pressure is possible by closed by means of the second electronic device, the separating valve, the second Druckbereitstellungseirichtung actuated and the spill valve are controlled. The overflow valve and the separating valve are particularly preferably activated or actuated exclusively by means of the second electronic device in order to dispense with more expensive, double-controllable valves.

The intake valves, and if present the exhaust valves, are preferably energized by the second electronic device. Thus, in the event of failure of the first pressure supply device or the first electronic device or the first energy supply, wheel-individual brake pressure curves can still be made by means of the second electronic device. The intake valves, and if present the exhaust valves, are particularly preferably exclusively controlled by the second electronic device in order to dispense with more expensive, double-controllable valves.

The brake system comprises according to a preferred embodiment, a wheel speed sensor for each wheel associated with a wheel or is connected to such. In this case, the wheel speed sensors are preferably supplied and / or evaluated by means of the second electronic device with electrical energy. Thus, in the event of a failure of the first electronic device, the wheel speeds of the second electronic device necessary for the wheel-specific brake pressure control are available. Particularly preferably, the wheel speed sensors are supplied and / or evaluated exclusively by means of the second electronic device with electrical energy. Thus, redundant wheel speed sensors and the associated signal connections are saved to the first electronic device.

The Kreistrennventil is preferably controlled by means of the first electronic device or supplied with electrical energy. Thus, in the event of failure of the second pressure supply device or the second electronic device or the second energy supply, brake circuit individual (i.e., brake circuit different) brake pressure curves can be made by the first Druckbereitstellungsseirichtung and the Kreistrennventil be operated by the first electronic device. The brake circuit different brake pressures are adjusted by a brake circuit multiplex method. With appropriate assignment of the wheel brakes to the axles of the motor vehicle achsinduelle Bremsdruckverläufe and achsweises diaphragms are possible by means of the Kreistrennventils.

The circular selector valve is particularly preferably activated or actuated exclusively by means of the first electronic device or supplied with electrical energy in order to dispense with a more costly, double-controllable valve.

The brake system comprises according to a further preferred embodiment, a driving dynamics sensor or connected to such. The vehicle dynamics sensor system particularly preferably comprises at least one measuring device for detecting one or more of the following variables: longitudinal acceleration, in particular vehicle longitudinal acceleration; Lateral acceleration, in particular vehicle lateral acceleration; Yaw rate; Steering angle. In this case, the vehicle dynamics sensor system is preferably supplied and / or evaluated with electrical energy by means of the first electronic device. Thus, in the event of a failure of the second electronic device, the driving dynamics variables of the first electronic device necessary for brake-circuit-specific brake pressure regulation and maintenance of stability are available. The vehicle dynamics sensor system is particularly preferably supplied and / or evaluated exclusively by means of the first electronic device with electrical energy. Thus, redundant sensors / measuring devices and the associated signal connections are saved to the second electronic device.

The brake system according to the invention is of the type "brake-by-wire". Preferably, the simulation device for driver request detection comprises a first, preferably redundantly designed, sensor for detecting a first physical variable, which characterizes the braking request of the driver, and a second, preferably redundantly designed, sensor for detecting a different second physical quantity, which the braking request of Vehicle driver characterizes. The first size can be a path and the second size can be a pressure or a force.

The invention also relates to a method for operating a brake system according to the invention.

Preferably, in case of failure of the first pressure supply device or the first electronic device or the first power supply, the isolation valve is closed, performed by the second pressure supply device, a pressure build-up and by means of the intake valves (6a-6d), and if available the exhaust valves, and the spill valve wheel-individual brake pressures set the wheel brakes. This is particularly preferably carried out by means of the second electronic device, which activates the second pressure supply device and the intake valves, the separating valve and the overflow valve, and if present the exhaust valves.

In case of failure of the second pressure supply device or of the second electronic device or of the second energy supply by means of the first pressure supply device, a pressure buildup is preferably carried out and by means of the circular valve for the first and the second line section individual, ie individual brake circuit, brake pressures set to the wheel brakes. This is particularly preferably carried out by means of the first electronic device, which activates or actuates the first pressure supply device and the circular valve.

Further preferred embodiments of the invention will become apparent from the dependent claims and the following description with reference to a figure.

• 1 ein Ausführungsbeispiel einer erfindungsgemäßen Bremsanlage.

It shows schematically

• 1 An embodiment of a brake system according to the invention.

In 1 is an embodiment of a brake system according to the invention for a motor vehicle with four hydraulically actuated wheel brakes 8a - 8d shown schematically. For example, the wheel brake is 8a the left front wheel (FL), the wheel brake 8b the right front wheel (FR), the wheel brake 8c the left rear wheel (RL) and the wheel brake 8d assigned to the right rear wheel (RR). The wheel brakes 8a . 8b So are the front axle VA and the wheel brakes 8c . 8d assigned to the rear axle HA. Other assignments of wheel brakes 8a - 8d to the wheels (FL, FR, RL, RR) are conceivable.

The brake system includes one by means of a brake pedal 1 actuatable simulation device 3 , a first electrically controllable pressure supply device 5 , a second electrically controllable pressure supply device 2 , a pressurized medium reservoir under atmospheric pressure 4 , and wheel-individual brake pressure modulation valves, which, for example, as an intake valves 6a - 6d and an exhaust valve 7a - 7d per wheel brake 8a - 8d are executed. Furthermore, according to the example, an electronic control unit 12 provided for controlling the electrically actuatable components of the brake system, for supplying energy to electrical components of the brake system and / or for evaluating signals from sensors of the brake system or from environmental sensors.

simulation device 3 has in a housing a simulator piston 31 which passes through a in a simulator back chamber 30 arranged elastic element 33 (Eg simulator spring) is supported on the housing. A piston rod 24 couples the pivoting movement of the brake pedal 1 due to a pedal operation with the translational movement of the simulator piston 31 , whose actuating travel of a preferably redundantly designed displacement sensor 25 is detected. As a result, the corresponding piston travel signal is a measure of the brake pedal actuation angle. It represents a braking request of a driver. For driver input acquisition is another sensor 20 provided one of the piston stroke of the simulator piston 31 independent physical quantity, which characterizes the braking request of the driver detected. This can be eg a force sensor or a pressure sensor.

The first electrically controllable pressure supply device 5 is designed as a hydraulic cylinder-piston arrangement (or a single-circuit electro-hydraulic actuator (linear actuator)) whose pistons 36 from a schematically indicated electric motor 35 with the interposition of a rotation-translation gear also shown schematically 39 is actuated, in particular can be moved back and forth to a pressure in a pressure chamber 37 build up and dismantle. The piston 36 limits the pressure chamber 37 the pressure supply device 5 , To control the electric motor is a rotor position of the electric motor 35 detecting, only schematically indicated rotor position sensor 44 intended.

To the pressure room 37 the first electrically controllable pressure supply device 5 is a system pressure line section 38 connected. line section 38 is via an electrically actuated, preferably normally open, isolation valve 26 with a brake supply line 13 connected via which the inlet connections of all intake valves 6a - 6d with the pressure room 37 the first electrically controllable pressure supply device 5 are connected. Through the isolation valve 26 Can the hydraulic connection between the pressure chamber 37 or the first pressure supply device 5 and the brake supply line 13 (and thus the inlet ports of the intake valves 6a - 6d ) controlled open and shut off.

According to example, pressure chamber 37 in an unactuated state of the piston 36 via one or more sniffer holes and a line 42 with the pressure medium reservoir 4 connected. This connection between pressure chamber 37 and direction 42 or pressure fluid reservoir 4 becomes during a (sufficient) actuation of the piston 36 in pressure build-up direction (to the right in 1 ) separated.

The first pressure delivery device 5 is a high-performance pressure actuator that realizes the normal braking function with the highest level of comfort and maximum dynamics in the error-free brake system.

The second electrically controllable pressure supply device 2 is advantageously designed as a piston pump, in particular a radial piston pump. It has a suction connection 23 , which has a hydraulic connection 41 with the pressure medium reservoir 4 communicates, and a pressure connection 27 , Of the pressure connection 27 the second pressure supply device 2 is with the brake supply line 13 connected so that the inlet ports of the intake valves 6a - 6d with the pressure connection 27 the second pressure supply device 2 are connected. Between the pressure connection 27 and the brake supply line 13 is, for example, no valve (eg further electrically actuated isolation valve) arranged.

The radial piston pump 2 is an overflow valve 32 assigned whose control can realize a pressure limit and pressure reduction. For this the pressure connection is 27 the second pressure supply device 2 over the overflow valve 32 with the suction connection 23 and thus with the pressure fluid reservoir 4 connected. The overflow valve 32 is, for example, normally closed and analog controlled. By means of the overflow valve 32 that of the second pressure supply device 2 be limited or reduced pressure provided for the wheel brakes.

The brake system comprises, as already mentioned, each hydraulically actuated wheel brake 8a - 8d an inlet valve 6a - 6d and an exhaust valve 7a - 7d , the hydraulically interconnected in pairs via center ports and to the wheel brake 8a - 8d are connected. The inlet valves 6a - 6d is one to the brake supply line 13 hinöff opening, unspecified check valve connected in parallel. The outlet connections of the outlet valves 7a - 7d are via a common return line 14 connected to the pressure medium reservoir 4. The inlet connections of all inlet valves 6a - 6d can by means of the brake supply line 13 be supplied with a pressure from the first pressure supply device 5 or, for example, in the event of failure of the first pressure supply device, from the second pressure supply device 2 provided.

In the brake supply line 13 is an electrically operable, advantageously normally open Kreistrennventil 40 is arranged, through which the brake supply line 13 in a first line section 13a , which with the second pressure supply device 2 is connected, and a second line section 13b which (via the separating valve 26 ) with the first pressure supply device 5 is connected, can be disconnected. Here is the first line section 13a with two of the intake valves, namely the intake valves 6a and 6b, hydraulically connected and the second conduit section 13b is hydraulically connected to the other intake valves, namely the intake valves 6c and 6d. By closing the circular valve 40 the brake system is thus hydraulically separated or split into two (partial) brake circuits I and II. Here, in the first brake circuit I, the second pressure supply device 2 with only the wheel brakes 8a and 8b connected, and in the second brake circuit II, the first pressure supply device 5 with only the wheel brakes 8c and 8d connected.

The brake system comprises each brake circuit I or II a pressure sensor 19. This is preferably in front of one of the wheel brakes, according to the wheel brakes 8a and 8d arranged.

According to the example, the brake system for leakage monitoring comprises a level measuring device 50 for determining a pressure medium level in the pressure medium reservoir 4 ,

Also associated with each wheel is, for example, a wheel speed sensor 10a-10d, which may be e.g. for anti-lock control functions (ABS) are required.

• • Längsbeschleunigung, insbesondere Fahrzeuglängsbeschleunigung
• • Querschleunigung, insbesondere Fahrzeugquerbeschleunigung
• • Gierrate
• • Lenkwinkel

The brake system continues to be equipped with driving dynamics sensors 60 connected or includes such. The driving dynamics sensor 60 comprises at least one measuring device for detecting one or more of the following variables:

• • Longitudinal acceleration, in particular longitudinal vehicle acceleration
• • lateral acceleration, in particular vehicle lateral acceleration
• Yaw rate
• • Steering angle

The first pressure delivery device 5 is assigned to the control of a first electronics or first electronic device B. The electronic device B is, for example, part of the electronic control unit 12, but it can also be designed as a separate unit or electronic control unit.

The second pressure supply device 2 is to drive a second electronics or second electronic device A assigned. The electronic device A is for example part of the electronic control unit 12, but it can also be designed as a separate unit or electronic control unit.

In this case, the second electronic device A is electrically independent of the first electronic device B.

The first electronic device B is powered by or includes a first electrical energy source. The first pressure delivery device 5 is also from the first electrical energy source or Energy supply supplied with energy. For the sake of simplicity, for example, the first pressure supply device 5 powered by the first electronic device B with energy (from the first electric power source). The first electrical energy source is eg a first vehicle electrical system.

The second electronic device A is supplied by or comprises a second electrical energy source or energy supply. The second pressure supply device 2 is also powered by the second electrical energy source or energy supply. For the sake of simplicity, for example, the second pressure supplying device 2 supplied with power (from the second electric power source) via the second electronic device A. The second electrical energy source is eg a second electrical system.

The second electrical energy source or energy supply is independent of the first energy source or energy supply.

Other components of the brake system are advantageously either the first electronic device B (which the first pressure supply device 5 actuates) or the second electronic device A (which the second pressure supply device 2 activates or actuates) assigned. That is, they are controlled by this device or operated and / or supplied with electrical energy and / or signal side connected to this device and / or are evaluated by this device. In 1 those components which are assigned to the first electronic device B (ie assigned to the so-called partition B) are identified by an arrow with B, while those components which are assigned to the second electronic device A are assigned (ie to the so-called partition A) , marked by an arrow with A. In order to avoid further redundancies, a component is advantageously only or exclusively accessible from one of the two electronic devices, but not from the other electronic device, or can be supplied or supplied with electrical energy or connected or evaluable on the signal side.

The overflow valve 3 and the isolation valve 26 are associated with the second electronic device A and are therefore controlled by means of the second electronic device A and / or supplied with electrical energy.

The inlet and outlet valves are also associated with the partition A and are controlled by the second electronic device A and / or supplied with electrical energy.

However, the circular valve is 40 assigned to the partition B and is controlled by means of the first electronic device B and / or supplied with electrical energy.

The wheel speed sensors 10a - 10d are assigned to the partition A and are supplied by means of the second electronic device A with electrical energy and / or evaluated by the second electronic device A.

The driving dynamics sensor 60 is assigned to the partition B and is supplied and / or evaluated by means of the first electronic device B with electrical energy.

The second partition A (second electronic device A and / or second power supply) and the first partition B (first electronic device B and / or first power supply) are electrically independent.

According to the example, the hydraulic components, in particular the components 2 . 3 . 5 . 6a - 6d . 7a - 7d . 32 . 40 and 26 , in a common module, ie in a single hydraulic control unit (HCU) arranged. The hydraulic control unit is the electronic control unit (ECU) 12 assigned. HCU and ECU are advantageously implemented in a manner known per se as one unit (HECU). It can also be provided two or more electronic control units.

An arrangement in two or more modules or hydraulic control and regulating units (HCU) is also conceivable. Also, each hydraulic control and regulating units (HCU) can be assigned its own electronic control unit (ECU). For example, the simulation device 3 be advantageously carried out in a separate module. Other divisions and further modules are conceivable.

In the following, various operating methods of the brake system will be described.

Falls one of the two pressure-providing facilities 2 or 5 due to an error (for example, due to a failure of one of the electrical energy sources), then the other pressure supply device 5 respectively. 2 via the brake supply line 13 (with normally open circular valve 40 ) all wheel brakes 8a - 8d actuate.

If the first pressure supply device fails 5 error condition, is by means of the second pressure supply device 2 associated second electronic device A, the isolation valve 26 closed to one Pressure medium volume loss through the beak hole of the failed pressure supply device 5 to avoid. This is the second pressure supply device 2 to the control, in particular of the electric motor of the radial piston pump, the second electronic device A assigned, which also the separating valve 26 controls or supplies the valve coil with electrical energy.

1. a) Ausfall der ersten Druckbereitstellungseinrichtung 5 Der zweiten elektronischen Vorrichtung A / zweiten Energieversorgung der zweiten Druckbereitstellungseinrichtung 2 (Partition A) sind neben dem Trennventil 26 auch die Radregelventile 6a-6d, 7a-7d zugeordnet, d.h. die Radregelventile 6a-6d, 7a-7d werden durch die zweite elektronische Vorrichtung A (zweite Partition A) angesteuert bzw. mit elektrischer Energie versorgt. Ebenso sind die Raddrehzahlsensoren 10a-10d der zweiten elektronische Vorrichtung A (zweiten Partition A) zugeordnet, d.h. deren Signale werden der zweite elektronische Vorrichtung A zugeführt und vorteilhafterweise durch die zweite elektronische Vorrichtung A ausgewertet. Die zweite elektronische Vorrichtung A bzw. Partition A führt nun quasi unverändert, wie grundsätzlich bekannt, Antiblockierregelungen und andere radindividuelle Bremsdruckregelfunktionen aus und realisiert zusammen mit der Möglichkeit, Bremsdruck aufzubauen, alle Rest-Bremsfunktionen.
2. b) Ausfall der zweiten Druckbereitstellungseinrichtung 2 Der ersten elektronischen Vorrichtung B / ersten Energieversorgung (Partition B) sind die erste Druckbereitstellungseinrichtung 5, das Kreistrennventil 40 sowie z.B. die Fahrdynamik-Sensorik 60 zugeordnet. Die Druckbereitstellungseinrichtung 5 ist der high-Performance Drucksteller, der im fehlerfreien System die Normalbremsfunktion in höchstem Komfort und Dynamik realisiert. Die Partition B bzw. die erste Druckbereitstellungseinrichtung 5 regelt den Druck auch bei Ausfall der Druckbereitstellungseinrichtung 2 noch immer mit sehr hoher Dynamik und Genauigkeit zentral. Die Ansteuerbarkeit des Kreistrennventils 40 durch die erste elektronische Vorrichtung B ermöglicht es sogar, dass achsweise unterschiedliche Drücke eingestellt werden können. Dies erfolgt nach einem Achs-Multiplex-Verfahren. Die Leistungsfähigkeit dieser Regelstrategie ist in Bezug auf Bremsleistung zwar nicht auf dem Niveau des fehlerfreien Systems. Es ist jedoch für den beschriebenen Fehlerfall ausreichend zur Sicherstellung der Rest-Bremsfunktionen.

Control strategy for residual brake function after an error:

1. a) Failure of the first pressure delivery device 5 The second electronic device A / second power supply of the second pressure supply device 2 (Partition A) are next to the isolation valve 26 also the wheel control valves 6a-6d, 7a-7d assigned, ie the wheel control valves 6a-6d, 7a-7d are controlled by the second electronic device A (second partition A) or supplied with electrical energy. Likewise, the wheel speed sensors 10a - 10d the second electronic device A (second partition A), ie their signals are supplied to the second electronic device A and advantageously evaluated by the second electronic device A. The second electronic device A or partition A now performs virtually unchanged, as is known in principle, anti-skid control and other wheel-specific brake pressure control functions and realized together with the ability to build up brake pressure, all residual brake functions.
2. b) Failure of the second pressure supply device 2 The first electronic device B / first power supply (partition B) are the first pressure providing device 5 , the circular valve 40 as well as the driving dynamics sensors 60 assigned. The pressure delivery device 5 is the high-performance pusher, which realizes the normal brake function in maximum comfort and dynamics in the error-free system. The partition B or the first print delivery device 5 regulates the pressure even if the pressure supply device fails 2 still central with very high dynamics and accuracy. The controllability of the circular valve 40 through the first electronic device B, it even allows different pressures to be set axle by axle. This is done by an axis-multiplexing method. The performance of this control strategy is not at the level of the faultless system in terms of braking performance. However, it is sufficient for the described error case to ensure the residual braking functions.

• - Verzögerung aufbauen;
• - Blockierreihenfolge der Achsen einhalten und ein ungewolltes Destabilisieren bei höheren Verzögerungen vermeiden;
• - Lenkbarkeit aufrechterhalten, um dem (Auto-)Pilot auch gebremste Ausweichmanöver zu ermöglichen.

The exemplary brake system provides the necessary redundancy for the realization of highly automated driving functions to implement autonomous braking requirements. Even after a serious error, such as a failure of the first power supply of the partition B or the first pressure supply device, the brake system is able to continue to implement certain residual braking functions autonomously or controlled by an autopilot. The most important residual brake functions of the brake system are:

• - build up delay;
• - Adhere to the blocking order of the axes and avoid unwanted destabilization at higher delays;
• - maintained steerability to allow the (car) pilot also braked evasive maneuvers.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102013223859 A1 [0002]
• DE 102013217954 A1 [0003]

Claims (15)

Brake system for a motor vehicle with • at least four hydraulically actuated wheel brakes (8a-8d), • a simulation device (3), • an electrically actuated intake valve (6a-6d) per wheel brake (8a-8d) for setting wheel-specific brake pressures, • a first electric controllable pressure supply device (5), which is separably hydraulically connected via a separating valve (26) to a brake supply line (13) to which the wheel brakes (8a-8d) are connected via in each case one of the inlet valves, and • a second electrically controllable pressure supply device (2 ), which is hydraulically connected to the brake supply line (13), wherein in the brake supply line (13) an electrically operable Kreistrennventil (40) is arranged such that when the closed Kreistrennventil the brake supply line (13) in a first and a second line section (13a, 13b) is hydraulically separated, wherein the first Leitungsabschnit t (13a) is hydraulically connected to two of the inlet valves (6a, 6b) and the second line section (13b) is hydraulically connected to the remaining inlet valves (6c, 6d), and wherein the second pressure supply device (2) is connected to the first line section (13a ) is hydraulically connected and the first pressure supply device (5) via the separating valve (26) to the second line section (13b) is hydraulically connected, characterized in that the second pressure supply device (2) comprises a suction port (23) and a pressure port (27) , wherein for adjusting or regulating the pressure provided by the second pressure supply device (2) an overflow valve (32) is provided, via which the pressure port (27) to the suction port (23) is hydraulically connected. Brake system after Claim 1 , characterized in that the overflow valve (32) is designed to be normally closed. Brake system after Claim 1 or 2 , characterized in that the simulation device (3) by means of a brake pedal (1) is actuated, and that no mechanical and / or hydraulic operative connection between the brake pedal and the wheel brakes is provided. Brake system according to one of the preceding claims, characterized in that the second pressure supply device (2) by a piston pump, in particular radial piston pump, is formed. Brake system according to one of the preceding claims, characterized in that the second pressure supply device (2) is hydraulically connected directly to the first line section (13a). Brake system according to one of the preceding claims, characterized in that the circular selector valve (40) is designed to be normally open. Brake system according to one of the preceding claims, characterized in that the separating valve (26) is designed to be normally open. Brake system according to one of the preceding claims, characterized in that the first pressure supply device (5) by a cylinder-piston arrangement with a hydraulic pressure chamber (37) is formed, the piston (36) by an electromechanical actuator (35, 39) is actuated wherein the pressure chamber is connected in an unactuated state of the piston (36) via at least one Schnuffelf with a conduit (42) to a pressure medium reservoir (4), said compound is separated upon actuation of the piston (36). Brake system according to one of the preceding claims, characterized in that it is a first electronic device (B), by means of which the first pressure supply means (5) is driven, and a second electronic device (A), by means of which the second pressure supply means (2) is driven , wherein the second electronic device (A) is electrically independent of the first electronic device (B). Brake system after Claim 9 characterized in that the first electronic device (B) is powered by a first electrical power supply or comprises a first electrical power supply, and that the second electronic device (A) is powered by a second electrical power supply or comprises a second electrical power supply the first electrical power supply is independent of the second electrical power supply. Brake system after Claim 9 or 10 , characterized in that the overflow valve (3) and the separating valve (26), in particular exclusively, by means of the second electronic device (A) controlled and / or supplied with electrical energy. Brake system after one of the Claims 9 to 11 , characterized in that the inlet valves, and optionally the outlet valves, in particular exclusively, by means of the second electronic device (A) are driven and / or supplied with electrical energy. Brake system after one of the Claims 9 to 12 , characterized in that the circular separating valve (40), in particular exclusively, by means of the first electronic device (B) is driven and / or supplied with electrical energy. Method for operating a brake system according to one of Claims 1 to 13 , characterized in that in case of failure of the first pressure supply device (5) or electronic device (B) or power supply, the separating valve (26) is closed, by means of the second pressure supply device (2), a pressure build-up is performed and by means of the inlet valves (6a-6d) , and in particular the exhaust valves (7a-7d), and the spill valve (32) wheel-specific brake pressures are set to the wheel brakes. Method for operating a brake system according to one of Claims 1 to 13 , especially after Claim 14 , characterized in that in case of failure of the second pressure supply device (2) or electronic device (A) or energy supply by means of the first pressure supply means (5), a pressure build-up is performed and set by the Kreistrennventils (40) for the first and the second line section individual brake pressures become.

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