CROSS-REFERENCE TO RELATED APPLICATION

This application is a national stage of International Application No. PCT/EP2018/058834, filed Mar. 19, 2018, the disclosure of which is incorporated herein by reference in its entirety, and which claimed priority to German Patent Application No. 102017003654.3, filed 13 Apr. 2017, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to the field of motor vehicle brake systems. Specifically, a hydraulic motor vehicle brake system and a control unit system therefore are described.

BACKGROUND

Known hydraulic motor vehicle brake systems, which are configured as a Brake-By-Wire (BBW) system or are equipped with an Electric Brake Boost (EBB) system, comprise an electrically actuable hydraulic pressure generator which, during normal braking operation, generates hydraulic pressure at wheel brakes of motor vehicle or boosts hydraulic pressure which is generated by a driver. To this end, a vehicle deceleration which is a result of the driver pressing a brake pedal, is detected by a sensor and is converted into an actuating signal for the electrically actuable hydraulic pressure generator.

Brake systems of this type, as a rule, also comprise a master cylinder which can be actuated mechanically by means of the brake pedal and via which hydraulic fluid can likewise be conveyed to the wheel brakes. The master cylinder which can be actuated by means of the brake pedal provides redundancy in relation to the electrically actuable hydraulic pressure generator of the BBW or EBB system, which is indispensable for reasons of operational safety.

Motor vehicle brake systems for autonomous or semi-autonomous driving also need to have redundancy in design. It cannot be assumed in such cases, however, that the driver is situated in the vehicle (for example, in a remote controlled parking (RCP) operation), or that the driver can actuate a brake pedal promptly (for example, in the case of said driver not looking at what is happening on the road). For this reason, it is required that, in addition to a functional unit which provides an electrically actuable brake master function, brake systems for autonomous or semi-autonomous driving also comprise a further functional unit which implements an electrically actuable auxiliary braking function in a redundant way.

SUMMARY

The present disclosure is based on the object of specifying a hydraulic motor vehicle brake system which has improved redundancy.

In accordance with a first aspect, a hydraulic motor vehicle brake system is specified. The hydraulic motor vehicle brake system comprises a vehicle dynamic control (Electronic Stability Control, ESC) system which is of dual-circuit configuration and which comprises a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions, and which can be actuated independently of the first hydraulic pressure generator. Furthermore, the hydraulic motor vehicle brake system comprises an electric parking brake (EPS) system with an electrically actuable first actuator which is assigned to one of the first wheel brakes, and an electrically actuable second actuator which is assigned to one of the second wheel brakes. Furthermore, the hydraulic motor vehicle brake system comprises a controller which is configured to detect a functional loss of at least one of the two brake circuits and a requirement of a control intervention on the at least one brake circuit which is affected by the functional loss, and, if the functional loss and the requirement of a control intervention are detected, to actuate at least one of the actuators for carrying out or assisting the control intervention.

Furthermore, the hydraulic motor vehicle brake system in accordance with the first aspect may comprise an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits. In this case, the controller can be configured to actuate the third hydraulic pressure generator, if the functional loss and the requirement of a control intervention are detected, in order to carry out or assist the control intervention.

Carrying out the control intervention can take place exclusively by means of the at least one actuated actuator. As an alternative to this, in addition to the at least one actuated actuator, a further component of the hydraulic motor vehicle brake system which is capable of control interventions can participate in the control intervention, with the result that the at least one actuator takes part in the control intervention in an assisting manner. In the case of a merely partial functional loss of the corresponding brake circuit, a component of this type can be, for example, the first and/or the second (or a third) hydraulic pressure generator.

A hydraulic motor vehicle brake system in accordance with a second aspect comprises a vehicle dynamic control (Electronic Stability Control, ESC) system which is of dual-circuit configuration and which comprises a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions and which can be actuated independently of the first hydraulic pressure generator. Furthermore the hydraulic motor vehicle brake system comprises an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits, and a controller which is configured to detect a functional loss of at least one of the two brake circuits and a requirement of a control invention on the at least one brake circuit which is affected by the functional loss, and, if the functional loss and the requirement of a control intervention are detected, to actuate at least the third hydraulic pressure generator, for carrying out or assisting the control intervention.

In one variant of the first or second aspect, the functional loss of the at least one brake circuit is detected as the requirement of a control intervention on the at least one brake circuit which is affected by the functional loss. In accordance with another variant, the requirement of a control intervention is detected at a separate time from the detection of the functional loss of the at least one brake circuit, for example at a later time. In said variant, the actuation of at least one of the actuators for carrying out or assisting the control intervention can take place immediately when the requirement of a control intervention is detected following the detection of the functional loss of the at least one brake circuit.

Exemplary control interventions comprise one or more of the following interventions: an anti-lock brake control operation, a traction control operation a vehicle dynamics control operation in the relatively strict sense (for example, for preventing oversteer or understeer), and a brake pressure control operation for an automatic distance control operation.

A hydraulic; motor vehicle brake system in accordance with a third aspect comprises a vehicle dynamic control (Electronic Stability Control ESC) system which is of dual-circuit configuration and which comprises a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions and which can be actuated independently of the first hydraulic pressure generator. Furthermore, the hydraulic motor vehicle brake system comprises an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits, and a controller which is configured to detect a functional loss of the third hydraulic pressure generator and a driver's braking request, and, if the functional loss of the third hydraulic pressure generator and the driver's braking request are detected, to actuate the first hydraulic pressure generator and/or the second hydraulic pressure generator, in order to generate a hydraulic pressure in at least one of the brake circuits in accordance with the driver's braking request.

Furthermore, the hydraulic motor vehicle brake system in accordance with the second or third aspect may comprise an electric parking brake (EPB) system with an electrically actuable first actuator which is assigned to one of the first wheel brakes, and an electrically actuable second actuator which is assigned to one of the second wheel brakes. In this case, the controller in accordance with the second aspect can be configured, if the functional loss of at least one of the two brake circuits and the requirement of a control intervention are detected, to actuate at least one of the actuators, in order to carry out or assist the control intervention. The controller in accordance with the third aspect can be configured, if the functional loss of the third hydraulic pressure generator and the driver's braking request are detected, to actuate at least one of the actuators in accordance with the driver's braking request.

The following embodiments apply for the hydraulic motor vehicle brake system in accordance with all of the aspects which are proposed here. In one realization, the hydraulic motor vehicle brake system is configured as a Brake-By-Wire (BBW) system which comprises the third hydraulic pressure generator, and/or is equipped with an Electric Brake Boost (EBB) system which comprises the third hydraulic pressure generator. In one alternative refinement, the hydraulic motor vehicle brake system is provided with an electrically actuable vacuum brake booster which acts as the third hydraulic pressure generator.

The BBW system can provide permanent mechanical decoupling of a brake pedal from a master cylinder of the hydraulic motor vehicle brake system. Said mechanical decoupling can be canceled in favor of a mechanical intervention (this is also called push through, PT) in the case of a fault in the BBW system.

It is possible for the EBB system or the electrically actuable vacuum brake booster not to provide mechanical decoupling of this type, or to provide it only in certain cases (for example, in the case of a regenerative braking operation), a force which acts on the master cylinder by means of the brake pedal being boosted with the use of the third hydraulic pressure generator in the case of the mechanical coupling. For this purpose, the third hydraulic pressure generator may comprise the master cylinder and an electromechanical actuator which acts mechanically on the master cylinder in addition to the brake pedal. As an alternative to this, the third hydraulic pressure generator may comprise a separate cylinder/piston arrangement which is coupled hydraulically to the master cylinder or the brake circuits, and an electromechanical actuator which acts on the cylinder/piston arrangement. The first actuator and the second actuator of the EPB system can be electrically actuated independently of one another. The actuators can be based on an electromechanical, an electropneumatic, or an electrohydraulic principle.

A first sensor for detecting a hydraulic pressure in the first brake circuit and a second sensor for detecting a hydraulic pressure in the second brake circuit can be provided. A signal of the first sensor can form a basis for the actuation of the first hydraulic pressure generator and/or the first actuator. A signal of the second sensor can form a basis for the actuation of the second hydraulic pressure generator and/or the second actuator. The first brake circuit and the second brake circuit can be of identical construction. The identical construction can relate, in particular, to the electrically actuable and/or hydraulically active components which are installed in the brake circuits.

The hydraulic motor vehicle brake system may comprise a first electric supply system which is configured to supply the first hydraulic pressure generator and/or the first actuator. In addition or as an alternative to this, the hydraulic motor vehicle brake system may comprise a second electric; supply system which is configured to supply the second hydraulic pressure generator and/or the second actuator. Each supply system can be assigned separate electric lines and a separate voltage source. Furthermore, the first electric supply system can be configured to supply the second hydraulic pressure generator and/or the second actuator. As an alternative or In addition to this, the second electric supply system can be configured to supply the first hydraulic pressure generator and/or the first actuator. Furthermore, the first electric supply system and/or the second electric supply system can be configured to supply the third hydraulic pressure generator.

At least one of the hydraulic pressure generators, in particular the first and/or the second and/or the third hydraulic pressure generator, can be configured as a motor/pump unit. This embodiment comprises, for example, a double-acting cylinder/piston arrangement which can be actuated by means of an electric motor (for example, in the manner of a plunger arrangement), a single-acting cylinder/piston arrangement (for example, in the manner of a plunger arrangement), a gear pump or a radial or axial piston pump.

In accordance with a fourth aspect, an electronic control unit system for the hydraulic motor vehicle brake system which is proposed here in accordance with the first, second or third aspect is specified. The electronic control unit system comprises a first control unit which is configured to actuate the first hydraulic pressure generator and the first actuator, and a second control unit which is configured to actuate the second hydraulic pressure generator and the second actuator. Furthermore, the electronic control unit system may comprise a third control unit which is configured to actuate the third hydraulic pressure generator. As an alternative to this, the first and/or the second control unit can be configured to actuate the third hydraulic pressure generator.

An electronic control unit system in accordance with a fifth aspect for the hydraulic motor vehicle brake system which is proposed here in accordance with the third aspect comprises a first control unit which is configured to actuate the first hydraulic pressure generator, a second control unit which is configured to actuate the second hydraulic pressure generator, and a third control unit which is configured to actuate the third hydraulic pressure generator.

If an EPB system is present, the first control unit of the system in accordance with the fifth aspect can be configured to actuate the first actuator, and the second control unit can be configured to actuate the second actuator. The following embodiments apply to the control unit system in accordance with the fourth aspect or in accordance with the fifth aspect.

In one variant, the first control unit is configured to be operated on the first electric supply system and/or on the second electric supply system. As an alternative or in addition to this, the second control unit is configured to be operated on the first electric supply system and/or on the second electric supply system. As an alternative or in addition to this, the third control unit is configured to be operated on the first electric supply system and/or on the second electric supply system. This increases the redundancy and availability of the system. For example, the control units are operated in parallel on the first electric supply system and on the second electric supply system. At least two of the control units (for example, the first control unit and the second control unit) can be configured to communicate with one another via a first communication system and a second communication system. This increases the redundancy and availability of the system. For example, the control units communicate in parallel via the first communication system and the second communication system.

The first control unit and the second control unit can form a spatially contiguous control unit assembly. For example, the two control units can be installed in a common housing or in separate housings which, however, are in turn mounted on the same component (for example, a hydraulic assembly). The first control unit may comprise at least one first processor, and the second control unit may comprise at least one second processor. The at least one first processor can be provided to actuate the first hydraulic pressure generator and the first actuator. The at least one second processor can be provided to actuate the second hydraulic pressure generator and the second actuator. The third control unit may comprise at least one third processor. The at least one first processor and the at least one second processor (and optionally the third processor) can be connected to one another communicatively via a processor interface. The processor communication may comprise the exchange and/or the plausibility check of actuating signals or measured variables (for example, of sensor data of the above-addressed hydraulic pressure sensors or other sensors).

In accordance with a sixth aspect, a method for operating a hydraulic motor vehicle brake system with an Electronic Stability Control (ESC) system and an Electric Parking Brake (EPB) system is specified, the ESC system being of dual-circuit configuration and comprising a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions and which can be actuated independently of the first hydraulic pressure generator, and the EPB system comprising an electrically actuable first actuator which is assigned to one of the first wheel brakes, and an electrically actuable second actuator which is assigned to one of the second wheel brakes. The method comprises the steps of detecting of a functional loss of at least one of the two brake circuits and of a requirement of a control intervention on the at least one brake circuit which is affected by the functional loss, and actuating, if the functional loss and the requirement of a control intervention are detected, of at least one of the actuators for carrying out or assisting the control intervention.

In accordance with a seventh aspect, a method for operating a hydraulic motor vehicle brake system with a vehicle dynamic control (Electronic Stability Control, ESC) system is specified, which is of dual-circuit configuration and which comprises a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions and which can be actuated independently of the first hydraulic pressure generator, and the brake system comprising, furthermore, an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits. The method comprises the steps of detecting of a functional loss of at least one of the two brake circuits and a requirement of a control intervention on the at least one brake circuit which is affected by the functional loss, and actuating, if the functional loss and the requirement of a control intervention are detected, of the third hydraulic pressure generator for carrying out or assisting the control intervention.

The following embodiments apply to the method in accordance with the sixth aspect or seventh aspect. An emergency braking operation can be carded out if the functional loss is detected or at a later time, for example in order to bring the vehicle to a standstill as rapidly as possible. In this case, the control intervention can take place within the context of the emergency braking operation, for example in order to maintain the vehicle stability during the emergency braking operation. Locking of a braked wheel can be detected as a requirement of a control intervention, the control intervention counteracting the locking of the braked wheel. As an alternative or in addition to this, a vehicle dynamics control operation can be detected as a requirement of a control intervention, the control intervention serving for the vehicle dynamics control operation.

As stated above, furthermore, the hydraulic motor vehicle brake system may comprise an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits. In this case, furthermore, the method may comprise actuating of the third hydraulic pressure generator, if the functional loss and the requirement of a control intervention are detected, namely in order to carry out or assist the control intervention. At least one of the following events can be detected as a functional loss of at least one of the two brake circuits: a functional loss of the first and/or second and/or third hydraulic pressure generator, a functional loss of a control unit which is assigned to the first and/or second and/or third hydraulic pressure generator, and a leak of at least one of the brake circuits.

In accordance with an eighth aspect, a method for operating a hydraulic motor vehicle brake system with a vehicle dynamic control (Electronic Stability Control, ESC) system is specified, which is of dual-circuit configuration and which comprises a first brake circuit which acts on one or more first wheel brakes, and a second brake circuit which acts on one or more second wheel brakes, the first brake circuit comprising a first hydraulic pressure generator which can be actuated electrically for control interventions, and the second brake circuit comprising a second hydraulic pressure generator which can be actuated electrically for control interventions and which can be actuated independently of the first hydraulic pressure generator, the hydraulic motor vehicle brake system comprising, furthermore, an electrically actuable third hydraulic pressure generator which is configured to generate a hydraulic pressure for at least one of the two brake circuits. The method comprises the steps of detecting a functional loss of the third hydraulic pressure generator and of a driver's braking request, and actuating, if the functional loss of the third hydraulic; pressure generator and the driver's braking request are detected, of the first hydraulic pressure generator and/or of the second hydraulic pressure generator, in order to generate a hydraulic pressure in at least one of the brake circuits in accordance with the driver's braking request.

Furthermore, a computer program is specified which comprises program code for carrying out the method which is proposed here in accordance with the sixth, seventh or eighth aspect when the computer program runs on a processor (that is to say, within a motor vehicle control unit). A motor vehicle control unit or control unit system (comprising a plurality of control units) is likewise specified, the control unit or control unit system having at least one processor and at least one memory, and the at least one memory comprising program code which, when it is carried out by the at least one processor, brings about the performance of the steps of the method which is specified here.

