DE102017222440A1 - Brake system for a motor vehicle and method for its operation - Google Patents

Abstract

Brake system for a motor vehicle with u.a. hydraulically actuable wheel brakes (8a-8d), an electrically actuated inlet valve (6a-6d) per wheel brake (8a-8d), a first electrically controllable pressure supply device (5) via a first separating valve (26) with a brake supply line (13) separable to which the wheel brakes (8a-8d) are connected, and a second electrically controllable pressure supply device (2) which is connected to the brake supply line (13), wherein in the brake supply line, an electrically operable Kreistrennventil (40) is arranged such that when the closed-loop valve is closed, the brake supply line is separated into first and second line sections (13a, 13b), the first line section (13a) being hydraulically connected to a portion of the inlet valves (6a, 6b) and the second line section (13b) being connected hydraulically the other part of the intake valves (6c, 6d) is hydraulically connected, and wherein the second Druckbereitstellu ngseinrichtung (2) is connected to the first line section (13a) and the first pressure supply device (5) via the first separating valve (26) with the second line section (13b) is connected, wherein the second pressure supply device (2) has a suction port (28) which is connected to the pressure medium reservoir (4), and a pressure port (27), wherein for adjusting or regulating the pressure provided by the second pressure supply device (2) a normally open overflow valve (32) is provided, via which the pressure port (27) is connected to the suction port (28), and wherein a normally open second separating valve (23) is provided, which is arranged in series with the overflow valve (32).

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 known, 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 a brake pedal-operated master cylinder, which is hydraulically connected to the wheel brakes for a fallback level, can be dispensed with.

This object is achieved by a brake system according to claim 1 and a method according to claim 16 or 17.

The invention is based on the idea of providing a brake system having at least two hydraulically actuable wheel brakes, a pressure medium reservoir under atmospheric pressure, at least one electrically actuable inlet valve per wheel brake for setting wheel-specific brake pressures, a first electrically controllable pressure supply device which can be separated via a first isolation valve with a brake supply line is hydraulically connected to which the wheel brakes are connected, and a second electrically controllable pressure supply device which is hydraulically connected to the brake supply line. In the brake supply line, an electrically operable circular valve is arranged such that when the Kreistrennventil closed the brake supply line is hydraulically separated into a first and a second line section, wherein the first line section is hydraulically connected to a part of the inlet valves and the second line section with the other part of the inlet valves is hydraulically connected, and wherein the second pressure-supplying device is hydraulically connected to the first line section and the first pressure-providing device is hydraulically connected via the first separating valve to the second line section. The second pressure supply device comprises a suction port, which is connected to the pressure medium reservoir, and a pressure port, wherein for adjusting or regulating the pressure provided by the second pressure supply device, a normally open overflow valve is provided, via which the pressure port is hydraulically connected to the suction port. That the overflow valve is connected in parallel to the second pressure supply device. In addition, a normally open second isolation valve is provided, which is arranged hydraulically in series with the overflow valve.

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.

Furthermore, the invention offers the advantage that for the connection of the second pressure supply device only normally open valves (the spill valve and the second isolation valve) are used, so that the brake system and in particular the wheel brakes are relieved of pressure in an unactuated state of the brake system (release position). Furthermore, the brake system has the advantage that for the two Pressure delivery devices different types of pressure sources can be used. While the first pressure supply device per se must be designed for precise and dynamic adjustment or regulation of the pressure provided by it, the second pressure supply device can be designed more cost-effective, since a precise and dynamic adjustment of the pressure provided by it by means of the overflow valve and possibly the second isolation valve is possible.

Preferably, the brake system comprises at least four hydraulically actuated wheel brakes, wherein in the brake supply line, the electrically operable Kreistrennventil is arranged such that when the closed Kreistrennventil the brake supply line is hydraulically separated in the first and the second line section, wherein the first line section is hydraulically connected to two of the intake valves and the second line section is hydraulically connected to the remaining inlet valves.

Preferably, the brake system further comprises a brake pedal and a simulation device.

The brake system preferably comprises an electrically actuatable outlet valve per wheel brake.

Preferably, the overflow valve is designed to be adjustable analogously in order to ensure precise adjustment or regulation of the pressure provided by the second pressure supply device.

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. An overflow valve of conventional design is particularly preferably used, into which a check valve closing towards the pressure fluid reservoir is integrated in parallel. In addition to design advantages, this makes it easier to perform the overflow valve analog adjustable.

Preferably, the second separating valve is designed to be adjustable analogously, in order to have as many options for printing position in particular in the case of failure of the second pressure-providing device.

Preferably, a check valve opening to the wheel brakes is connected in parallel with the second isolation valve. This makes it easier to carry out the second separating valve analog adjustable, and the flow resistance of the second pressure supply device to the wheel brakes 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 may, e.g. in the event of leakage, be separated by closing the circular valve in a first hydraulic brake circuit and a second hydraulic brake circuit. The first hydraulic brake circuit comprises the second pressure supply device with the overflow valve and the second isolation valve, the first line section, and at least one wheel brake with the associated intake valve, more preferably two of the four wheel brakes with the associated two intake valves. The second hydraulic brake circuit comprises the first pressure supply device, the first separating valve, the second line section and the other wheel brake or other wheel brakes with the associated inlet valve, particularly preferably the other wheel brakes of the at least four 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 simulation device is preferably actuated by means of the brake pedal and no mechanical and / or hydraulic operative connection is provided between the brake pedal and the wheel brakes.

The simulation device gives the driver a pleasant brake pedal feel.

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 second vehicle axle, advantageously the rear axle, and the wheel brakes connected to the second line section are assigned to the first vehicle axle, advantageously to the front axle.

Preferably, the brake system per wheel brake comprises an electrically actuated inlet valve and an electrically actuated outlet valve for setting wheel-specific brake pressures. Particularly preferably, the respective wheel brake is connected by means of the outlet valve with the pressure medium reservoir. Advantageously, the outlet valves are connected via a common hydraulic connection with the under pressure pressure medium reservoir. The wheel-specific brake pressures are particularly preferred derived in a brake supply pressure in the brake supply line, wherein in a non-actuated state, the inlet valves forward the brake supply pressure to the wheel brakes and lock the outlet valves outflow of pressure medium from the wheel brakes.

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 first pressure-supplying device is formed by a cylinder-piston arrangement with a hydraulic pressure chamber, the piston is actuated by an electromechanical actuator, wherein the piston is advanced for pressure buildup by means of the electromechanical actuator and driven back to reduce pressure by means of 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. Particularly preferably, the cylinder-piston arrangement is executed without a Schnüffelloch, as already given a pressure relief in the release position via the normally open spill valve and the normally open second isolation valve. Particularly preferably, the pressure chamber of the first pressure supply device for sucking in pressure medium (independent of an actuation of the piston of the first pressure supply device) via a Nachsaugleitung with a closing in the direction of the pressure medium reservoir check valve connected to the pressure medium reservoir.

Particularly preferably, the first pressure-providing device comprises a single pressure chamber, wherein the pressure chamber is connected separably to the brake supply line via exactly one separating valve, namely the first separating valve. Particularly preferably, the first isolation valve is designed to be normally closed.

According to a first development of the invention, the second isolation valve is arranged hydraulically in series with the second pressure supply device. Particularly preferably, the second pressure supply device is hydraulically connected via the second separating valve to the brake supply line or to the first line section.

According to a second development of the invention, the second isolation valve is arranged hydraulically parallel to the second pressure supply device. More preferably, the pressure port of the second pressure delivery device is direct, i. without the interposition of an electrically operable valve, hydraulically connected to the first line section.

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 a failure of the first electronic device does not cause a 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, by means of the second electronic device, the second Pressure supply device operated or controlled. Preferably, the second pressure supply device is also supplied by the second electronic device with electrical energy.

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

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 first isolation valve is preferably controlled and / or supplied with electrical energy by means of the first electronic device, so that in the event of failure of the second pressure supply device or the second electronic device or the second energy supply by means of the first electronic device, the first pressure supply device by opening the first isolation valve Connected brake supply line and the wheel brakes can be acted upon by the pressure of the first pressure supply device. For the reasons already mentioned above, the first separating valve is particularly preferably driven or actuated exclusively by means of the first electronic device.

Preferably, the second isolation valve is controlled by the first electronic device and / 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 power supply by means of the first electronic device, the second isolation valve to be closed at a pressure buildup by means of the first pressure supply device, a flow of pressure medium from the brake supply line via the overflow valve in the pressure medium reservoir prevent. In order to avoid further redundancy and thus costs, the second isolation valve is particularly preferably driven or actuated exclusively by means of 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 are actuated 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.

Preferably, the simulation device is associated with a first sensor for detecting a first driver's brake desired quantity (for example a brake pedal travel) and a second sensor for detecting a second driver's brake desired variable (for example a pedal force or pressure) that is different from the first driver's brake desired variable. In this case, one of the sensors, advantageously exclusively, is connected to the first electronic device and is supplied and / or evaluated by it with electrical energy. The other of the sensors is, in particular exclusively, connected to the second electronic device and is supplied and / or evaluated by the latter with electrical energy. Thus, even if one of the electronic devices of the other electronic device fails, a driver brake request signal is available to control the associated pressure supply device.

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

Preferably, in the event of failure of the first pressure supply device or the first electronic device or the first power supply, the first isolation valve is closed and a pressure buildup is carried out by means of the second pressure supply device and wheel-specific brake pressures are transmitted by means of the intake valves, and if present the exhaust valves, and the overflow valve set the wheel brakes.

Preferably, in the event of failure of the second pressure supply device or the second electronic device or the second power supply, the second isolation valve is closed and a pressure buildup is performed by means of the first pressure supply device and individual brake pressures are adjusted by means of the recirculation valve and the second isolation valve for the first and second line sections.

Further preferred embodiments of the invention will become apparent from the subclaims and the following description with reference to figures.

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

It show schematically

• 1 a first embodiment of a brake system according to the invention, and
• 2 A second 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 rear wheel (RL), the wheel brake 8b the right rear wheel (RR), the wheel brake 8c the left front wheel (FL) and the wheel brake 8d assigned to the right front wheel (FR). The wheel brakes 8a . 8b So are the rear axle HA and the wheel brakes 8c . 8d assigned to the front axle VA. 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 , wheel-individual brake pressure modulation valves, which, for example, as an intake valves 6a - 6d and one exhaust valves 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. 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. The pipe section 38 is via an electrically actuated, preferably normally closed, first 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 first isolation valve 26 Can the hydraulic connection between the pressure chamber 37 or the first electrically controllable pressure supply device 5 and the brake supply line 13 (and thus the input ports of the intake valves 6a-6d) controlled open and shut off.

pressure chamber 37 is, regardless of the operating state of the piston 36, via a (Nachsaug-) line 42 with the pressure medium reservoir 4 connected. In the line 42 is one in the direction of the pressure medium reservoir 4 closing check valve 53 is arranged. A suction of pressure medium in the pressure chamber 37 is so by a retraction of the piston 36 with closed isolation valve 26 possible. The cylinder-piston arrangement 5 has no sniffer holes.

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 28 , which has a hydraulic connection 41 with the pressure medium reservoir 4 communicates, and a pressure connection 27 , 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.

The second pressure supply device 2 is on the one hand 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 28 and thus the pressure medium reservoir 4 connected. The overflow valve 32 is designed to be normally open, and advantageously designed analog controllable. 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.

According to example, between the second pressure providing device 2 and the pressure fluid reservoir 4 a parallel connection of the normally open, analog adjustable overflow valve 32 and a pressure fluid reservoir 4 closing check valve 63 arranged.

The second pressure supply device or piston pump 2 is also a (second) isolation valve 23 assigned, which hydraulically in series with the overflow valve 32 is arranged.

According to the embodiment of the 1 is the isolation valve 23 hydraulically in series with the second pressure supply device 2 arranged. Accordingly, the second pressure supply device 2 via the (second) isolation valve 23 with the brake supply line 13 or with the first line section 13a hydraulically connected. The second isolation valve 23 is advantageously one of the wheel brakes 8a - 8d or the brake supply line 13 opening check valve 43 connected in parallel.

According to an alternative embodiment, not shown, the (second) isolation valve 23 hydraulically parallel to the second pressure supply device 2 arranged. Ie the pressure connection 27 the second pressure supply device 2 is via a series connection of (second) isolation valve 23 and overflow valve 32 with the suction connection 28 and thus the pressure medium reservoir 4 connected while in the hydraulic connection between the pressure port 27 and the first line section 13a no electrically operable valve is arranged.

About the two described normally open valves 32 and 23 the pressure relief of the brake system is guaranteed in the release position. In particular, as the first pressure-providing device 5 a linear actuator without a beak hole be used, and the isolation valve 26 between pressure supply device 5 and brake supply line 13 can be performed a known per se, normally closed valve.

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 case 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 actuated, normally open circular selector valve 40 arranged, through which the brake supply line 13 in a first line section 13a , which (for example, via the second isolation valve 23 ) is connected to the second pressure supply device 2, and a second line section 13b , which (via the first 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 line section 13b is with the other intake valves, namely the intake valves 6c and 6d , hydraulically connected. 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 (via the isolation valve 26).

The brake system comprises each brake circuit I or II a pressure sensor: a first pressure sensor 19 , which is the first pressure supply device 5 is assigned, and a second pressure sensor 49 , which is the second pressure supply device 2 assigned. Advantageously, the pressure sensors are connected close to the respective pressure supply device, which is advantageous for operation and self-diagnosis.

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
• • Querbeschleunigung, 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

According to the example, the brake system comprises an electric parking brake (EPB) on the wheels of the rear axle HA. This can be integrated in the hydraulic wheel brakes, so-called integrated electric parking brake.

The first pressure delivery device 5 is assigned to the control of a first electronics or first electronic device A. 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.

The second pressure supply device 2 is to drive a second electronics or second electronic device B assigned. 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.

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

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

The second electronic device B is powered by or includes a second electrical energy source. 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 powered by the second electronic device B with energy (from the second electrical energy source). 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 A (which the first pressure supply device 5 actuates) or the second electronic device B (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 A (ie assigned to the so-called partition A) are identified by an arrow with A, while those components which are assigned to the second electronic device B are assigned to the so-called partition B , marked by an arrow with B. 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 first isolation valve 26 and the circular valve 40 are assigned to the first electronic device A and are consequently controlled by means of the first electronic device A and / or supplied with electrical energy. Because the first isolation valve 26 is associated with the first electronic device A, in the event of failure of the second electronic device B or the second power supply, a pressure in the brake supply line 13 (and thus the wheel brakes 8a - 8d ) by means of the first pressure supply device 5 be built up and dismantled. In case of failure of the first electronic device A or the first power supply, however, the pressure supply device 5 by the normally closed isolation valve 26 hydraulically separated.

Also the second isolation valve 23 is assigned to the first electronic device A and is controlled by means of the first electronic device A and / or supplied with electrical energy. In case of failure of the second electronic device B or the second power source so the normally open isolation valve 23 closed to a pressure reduction via the overflow valve 32 to avoid. The second separating valve 23 is driven or supplied, for example, only by the first electronic device A.

The driving dynamics sensor 60 is also associated with the partition A and is supplied and / or evaluated by means of the first electronic device A with electrical energy.

However, the overflow valve 32 associated with the partition B and is controlled by the second electronic device B and / or supplied with electrical energy, which also includes the second pressure providing device 2 activates / supplies. overflow 32 is driven according to the example only by means of the second electronic device B and / or supplied with electrical energy.

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

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

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 . 5 . 6a - 6d . 7a - 7d . 32 . 23 . 40 and 26 , in a first module, ie in a first hydraulic control unit (HCU), arranged during the simulation device 3 with the sensors 25 . 20 is executed in a separate, second module. The first hydraulic control unit is at least one electronic control unit (ECU) 12 assigned, which in 1 is shown very schematically. HCU and ECU 12 are advantageously carried out in a known manner as a unit (HECU). The module of the simulation facility 3 is preferably assigned its own, second electronic control unit (ECU), which in 1 is not shown (but see reference numerals 112 in 2 and 3 ).

Alternatively, an arrangement of the hydraulic or mechanical components 2 . 3 . 5 . 6a - 6d . 7a - 7d . 32 . 23 . 40 and 26 in a common module, ie in a common hydraulic control unit (HCU) conceivable.

The brake system does not include a master cylinder operable by a brake pedal, which is connected or connectable to the wheel brakes or at least a portion of the wheel brakes, and thus enables a fallback by operator actuation of the wheel brakes.

The simulation device 3 is by means of the brake pedal 1 operated and there is no mechanical and / or hydraulic operative connection between the brake pedal 1 and the wheel brakes 8a-8d provided. The simulation device 3 is with none of the wheel brakes 8a - 8d hydraulically connected.

2 shows a second embodiment of a brake system according to the invention. The second embodiment comprises on the one hand with respect to the hydraulic layout some differences from the embodiment of 1 and on the other additional components or connections to other components. The additional components or connections to other components can be used individually or in various combinations, also in conjunction with the first embodiment of the 1 be provided.

First, the differences become too 1 regarding the hydraulic layout.

The second pressure supply device 2 is designed as a two-circuit radial piston pump whose two pressure sides are interconnected to a pressure port 27 , Accordingly, the two pressure sides of the two-circuit radial piston pump to a suction port 28 connected to the pressure medium reservoir 4 connected.

The second isolation valve 23 is normally open, but not analog controlled.

The second isolation valve 23 no check valve is connected in parallel.

Now, the other components of the brake system or the connection of the brake system to other components, e.g. Vehicle components or controls described.

According to the example, the brake system comprises an electric parking brake (EPB) on the wheels of the rear axle HA. This is integrated, for example, in the hydraulic wheel brakes, so-called integrated electric parking brake (IPB).

The components 2 . 5 . 6a - 6d . 7a - 7d . 32 . 23 . 40 and 26 are arranged in a first hydraulic control unit (HCU1) having a first electronic control unit (ECU 1 ) 12 is assigned. ECU 12 includes a portion of the first electronic device A and a portion of the second electronic device B. The portion of the electronic device A is from a first source of electrical energy 57 , eg a battery or a vehicle electrical system supplied. The part of the electronic device B is supplied by a second electrical energy source 67, for example a second battery or a second vehicle electrical system. The ECU 12 For this purpose, for example, comprises two separate printed circuit boards, a first printed circuit board for the part of the first electronic / electronic device A and a second printed circuit board for the part of the second electronic / electronic device B.

The part of electronics A in ECU 12 includes, for example, the electrical and electronic components and valve coils for controlling the valves 23 . 26 and 40 , It further comprises the electrical and electronic components for controlling the electric motor 35 the first pressure supply device 5 ,

The part of electronics A in ECU 12 further includes the electrical and electronic components for signal processing or evaluation of the rotor position sensor 44 ,

The part of electronics A in ECU 12 further comprises the electrical and electronic components for signal processing or evaluation of the first pressure sensor 19 the first pressure supply device 5 ,

The part of electronics A in ECU 12 is connected to a first data bus 58, eg a first CAN bus.

The part of electronic device / electronics A in ECU 12 signals from (eg four) radindividual wheel speed sensors are fed, which in 2 through the block 56 are indicated.

The part of electronic device / electronics A in ECU 12 continues to be the signal of a man-machine interface 55 (HMI), eg a switch, for activating or deactivating a vehicle dynamics control function (ESC) or similar. fed. Depending on this, in the part of the electronic device / electronics A in ECU 12 the signals of a Driving dynamics sensors (driving dynamics sensors 60 in 1 ) evaluated and taken into account for printing.

The part of electronics B in ECU 12 includes the electrical and electronic components for controlling the electric motor of the second pressure supply device 2 , It also includes the electrical and electronic components as well as valve coils for controlling the valves 32 . 6a - 6d and 7a - 7d ,

The part of electronics B in ECU 12 further comprises the electrical and electronic components for signal processing or evaluation of the second pressure sensor 49 the second pressure supply device 2 ,

The part of electronics B in ECU 12 further comprises electrical and electronic components for controlling the electric parking brakes IPB of the rear axle HA. In 2 are corresponding control lines 70 indicated.

The part of electronics B in ECU 12 the signal becomes a human-machine interface 54 (HMI), for example a switch, for actuating the electric parking brake (IPB, EPB), which is arranged on the wheels of the rear axle HA supplied.

The part of electronics B in ECU 12 is connected to a second data bus 68, eg a second CAN bus. The first and the second data bus are advantageously independent of each other.

The part of electronics B in ECU 12 signals from (eg four) further or independent wheel-specific wheel speed sensors are supplied, which are in 2 through the block 66 are indicated.

The simulation device 3 with the sensors 25 . 20 is arranged in a second module to which a second electronic control unit (ECU) 112 assigned. Part of the electronics of ECU 112 belongs to the first electronic device / electronics A. Another part of the electronics of ECU 112 belongs to the second electronic device / electronics B. Accordingly, the part of the electronic device A in ECU 112 from the first source of electrical energy 57 and the part of the electronic device B in ECU 112 from the second electrical energy source 67 ,

The part of electronic device / electronics A in ECU 112 is also with the first data bus 58 connected.

The part of electronics A in ECU 112 includes the electrical and electronic components for signal conditioning or evaluation of the force or pressure sensor 20 ,

The part of electronics A in ECU 112 is, for example, for transmitting the signals from the sensor 20 additionally directly via a signal connection line or communication connection line 71 to the part of the electronics A in ECU 12 connected.

The part of electronic device / electronics B in ECU 112 is also with the second data bus 68 connected.

The part of electronics B in ECU 112 includes the electrical and electronic components for signal processing or evaluation of the displacement sensor 25 ,

Both electro-hydraulic control unit HCU1 and ECU 12 as well as the unit from simulation facility 3 and ECU 112 are preferably mounted on the bulkhead or landing gear, which passes through the block 59 is indicated schematically.

In the following, various operating methods of the exemplary brake systems 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 or one of the electronic devices A, B), 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 due to an error (for example, due to a failure of the associated electric power source or the electronic device A), the second electronic device B controls the second pressure providing device 2 to build up a brake pressure. The first pressure delivery device 5 is by the normally closed first isolation valve 26 from the brake supply line 13 hydraulically isolated. By means of the second electronic device B, the inlet valves ( 6a - 6d ) and exhaust valves ( 7a - 7d ) as well as the overflow valve 32 driven or their valve coils supplied with electrical energy for adjusting wheel-specific brake pressures to the wheel brakes 8a - 8d ,

Falls the second pressure delivery device 2 due to an error (for example due to a failure of the associated electrical energy source or the electronic device B), the first electronic device A controls the first pressure supply device 5 to build a Brake pressure for the wheel brakes 8a - 8d at. In addition, by means of the first electronic device A, the second isolation valve 32 is closed to a loss of pressure medium in the pressure medium reservoir 4 to avoid.

1. a) Ausfall der ersten Druckbereitstellungseinrichtung 5 Der zweiten elektronischen Vorrichtung B / zweiten Energieversorgung der zweiten Druckbereitstellungseinrichtung 2 (Partition B) sind neben dem Überströmventil 32 auch die Radregelventile 6a-6d, 7a-7d zugeordnet, d.h. die Radregelventile 6a-6d, 7a-7d werden, bevorzugt lediglich, durch die zweite elektronische Vorrichtung B (zweite Partition B) angesteuert bzw. mit elektrischer Energie versorgt. Ebenso sind der zweiten elektronische Vorrichtung B (zweiten Partition B) Raddrehzahlsensoren 10a-10d bzw. 66 zugeordnet, d.h. deren Signale werden der zweite elektronische Vorrichtung B zugeführt und vorteilhafterweise durch die zweite elektronische Vorrichtung B ausgewertet. Die zweite elektronische Vorrichtung B bzw. Partition B 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 A / ersten Energieversorgung (Partition A) sind die erste Druckbereitstellungseinrichtung 5, das Kreistrennventil 40, das erste Trennventil 26 und das zweite Trennventil 23 sowie die Fahrdynamik-Sensorik 60 zugeordnet.

Control strategy for residual brake function after an error:

1. a) Failure of the first pressure delivery device 5 The second electronic device B / second power supply of the second pressure supply device 2 (Partition B) are next to the overflow valve 32 also the wheel control valves 6a - 6d . 7a - 7d assigned, ie the wheel control valves 6a - 6d . 7a - 7d are driven, preferably only, by the second electronic device B (second partition B) or supplied with electrical energy. Likewise, the second electronic device B (second partition B) are wheel speed sensors 10a - 10d respectively. 66 that is, their signals are supplied to the second electronic device B and advantageously evaluated by the second electronic device B. The second electronic device B or partition B now performs virtually unchanged, as is known in principle, anti-lock regulations and other wheel-specific brake pressure control functions and realized together with the possibility to build up brake pressure, all residual brake functions.
2. b) Failure of the second pressure supply device 2 The first electronic device A / first power supply (partition A) are the first pressure providing device 5 , the circular valve 40 , the first isolation valve 26 and the second isolation valve 23 as well as the driving dynamics sensor 60 assigned.

The first electronic device A or partition A can thus by means of the first pressure providing device 5 by closing the second isolation valve 23 and opening the first isolation valve 26 build up a central pressure and regulate it with very high dynamics and accuracy. The controllability of the circular valve 40 By the first electronic device A, it is even possible for different pressures to be set in terms of brake circuit or 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 braking systems provide the redundancy necessary for the realization of highly automated driving functions in order to implement autonomous braking requirements. Even after a serious error, such as a failure of the first power supply of the partition A or the first pressure delivery device 5 , 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.

The exemplary brake systems each comprise two electrically controllable pressure supply devices 5 . 2 , a wheel pressure modulation group 6a - 6d . 7a - 7d as well as for the second pressure delivery device 2 a normally open, in particular analog controllable, overflow valve 32 and a second normally open isolation valve 23 , which can be closed if necessary, to a pressure reduction via the overflow valve 32 to avoid. For this purpose, the second separating valve 23 in series with the overflow valve 32 arranged. To the second pressure supply device 2 is the second isolation valve 23 in series (see 1 ) or arranged in parallel. In particular, there is no hydraulic fallback in the brake system but a permanent hydraulic decoupling of the driver.

• • In der ersten Druckbereitstellungseinrichtung 5 muss kein Schnüffelloch zur Druckentlastung der Bremsanlage in der Lösestellung vorgesehen sein, da eine Druckentlastung der Bremsanlage in der Lösestellung über die zwei stromlos offenen Ventile 23 und 32 gewährleistet ist.
• • Das erste Trennventil 26 kann stromlos geschlossen ausgeführt sein, so dass an sich bekannte, kostengünstige Ventile benutzt werden können. Es muss kein besonderer konstruktiver Aufwand betrieben werden, um ein stromlos offenes Ventil mit sehr geringem Strömungswiderstand bereitzustellen, um die notwendige Druckaufbaudynamik zu erreichen.
• • Aufgrund des in Reihe geschalteten zweiten Trennventils 23 kann das Überströmventil 32 ein stromlos offenes Analogventil sein, so dass an sich bekannte, kostengünstige Ventile benutzt werden können. Es muss kein besonderer konstruktiver Aufwand betrieben werden, um ein stromlos geschlossenes Analogventil bereitzustellen, welches bei Verwendung nur eines Überströmventils 32 notwendig wäre.

The exemplary brake systems continue to offer the following advantages:

• • In the first pressure delivery device 5 no Schnüffelloch must be provided to relieve the pressure of the brake system in the release position, as a pressure relief of the brake system in the release position on the two normally open valves 23 and 32 is guaranteed.
• • The first isolation valve 26 can be executed normally closed, so that known, inexpensive valves can be used. It does not have to operated special design effort to provide a normally open valve with very low flow resistance in order to achieve the necessary pressure build-up dynamics.
• • Due to the series-connected second isolation valve 23 can the overflow valve 32 be a normally open analog valve, so that known, inexpensive valves can be used. There is no need for special design effort to provide a normally closed analog valve, which when using only a spill valve 32 would be necessary.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

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

Claims (17)

Brake system for a motor vehicle with • at least two hydraulically actuated wheel brakes (8a-8d), • a pressurized medium reservoir (4) under atmospheric pressure, • an electrically actuated inlet valve (6a-6d) per wheel brake (8a-8d) for setting wheel-specific brake pressures, a first electrically controllable pressure supply device (5), which is hydraulically connected separably via a first isolation valve (26) to a brake supply line (13) to which the wheel brakes (8a-8d) are connected, 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 isolated, wherein the first line portion (13a) is hydraulically connected to a part of the intake valves (6a, 6b) and the second pipe portion (13b) is hydraulically connected to the other part of the intake valves (6c, 6d), and wherein the second pressure supply means (2) is connected to the first one Line section (13a) is hydraulically connected and the first pressure supply device (5) via the first separating valve (26) to the second line section (13b) is hydraulically connected, characterized in that the second pressure supply device (2) has a suction port (28), which with the pressure medium reservoir (4) is connected, and a pressure connection (27), wherein for adjusting or regulating the pressure provided by the second pressure supply device (2) a normally open overflow valve (32) is provided, via which the pressure port (27) with the Suction port (28) is hydraulically connected, wherein a normally open second isolation valve (23) vo is provided, which is arranged hydraulically in series with the overflow valve (32). Brake system after Claim 1 , characterized in that the Kreistrennventil (40) is designed to be normally open. Brake system after Claim 1 or 2 , characterized in that the second pressure supply device (2) is formed by a piston pump, in particular a radial piston pump, and the first pressure supply device (5) is formed by a cylinder-piston arrangement with a hydraulic pressure chamber (37) whose piston ( 36) by an electromechanical actuator (35, 39) is actuated, wherein the cylinder-piston assembly in particular has no Schnüffelloch. Brake system according to one of the preceding claims, characterized in that the overflow valve (32) in a hydraulic connection between the first line section (13a) and the pressure medium reservoir (4) is arranged, wherein the overflow valve (32) to the pressure medium reservoir (4) out closing check valve (63) is connected in parallel. Brake system according to one of the preceding claims, characterized in that the second separating valve (23) is arranged hydraulically in series with the second pressure supply device (2). Brake system according to one of the preceding claims, characterized in that the second pressure supply device (2) via the second separating valve (23) to the first line section (13a) is hydraulically connected. Brake system after one of the Claims 1 to 4 , characterized in that the second isolation valve (23) is arranged hydraulically parallel to the second pressure supply device (2). Brake system according to one of the preceding claims, characterized in that the first separating valve (26) is designed to be normally closed. Brake system according to one of the preceding claims, characterized in that it is a first electronic device (A), by means of which the first pressure supply means (5) is driven, and a second electronic device (B), by means of which the second pressure supply means (2) is driven , wherein the second electronic device (B) is electrically independent of the first electronic device (A). Brake system after Claim 9 characterized in that the first electronic device (A) is powered by a first electrical power supply or comprises a first electrical power supply, and that the second electronic device (B) 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 (32), in particular exclusively, by means of the second electronic device (B) is driven and / or supplied with electrical energy. Brake system after one of the Claims 9 to 11 , characterized in that the inlet valves, and optionally outlet valves, in particular exclusively, by means of the second electronic device (B) are driven and / or supplied with electrical energy. Brake system after one of the Claims 9 to 12 , characterized in that the first separating valve (26), in particular exclusively, by means of the first electronic device (A) is driven and / or supplied with electrical energy. Brake system after one of the Claims 9 to 13 , characterized in that the second separating valve (23), in particular exclusively, by means of the first electronic device (A) is driven and / or supplied with electrical energy. Brake system after one of the Claims 9 to 14 , characterized in that the Kreistrennventil (40), in particular exclusively, by means of the first electronic device (A) is driven and / or supplied with electrical energy. Method for operating a brake system according to one of Claims 1 to 15 , characterized in that in case of failure of the first pressure supply device (5) or electronic device (A) or power supply, the first isolation valve (26) remains 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 the overflow valve (32) wheel-individual brake pressures are set to the wheel brakes. Method for operating a brake system according to one of Claims 1 to 15 , especially after Claim 16 , characterized in that in case of failure of the second pressure supply device (2) or electronic device (B) or power supply, the second isolation valve (23) is closed, by means of the first pressure supply means (5), a pressure build-up is carried out and by means of the Kreistrennventils (40) and the second isolation valve (23) for the first and the second line section individual brake pressures are set.

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