Electrohydraulic motor vehicle brake system and method for ventilation of the simulator circuit thereof; method for testing the functionality of a further electrohydraulic motor vehicle brake system, and computer program products for the methods

A method for checking a functionality of an electrohydraulic brake system for a vehicle, comprising a hydraulic simulator circuit for generation of a pedal response force, a first cylinder-piston device, an electromechanical actuator acting on the first cylinder-piston device for generation of a hydraulic pressure and a first fluid path having a first valve unit arranged therein for a selective fluidic connection of the first cylinder-piston device to the hydraulic simulator circuit, wherein the method comprises the following steps:

• switching of the first valve unit from a closed state to an open state, in order to connect the hydraulic simulator circuit fluidically to the first cylinder-piston device;
• operating the electromechanical actuator to displace hydraulic fluid from the first cylinder-piston device via the first fluid path into the simulator circuit;
• detecting a hydraulic pressure prevailing on account of the displaced hydraulic fluid;
• and
• checking of the functionality of the electrohydraulic vehicle brake system on the basis of the hydraulic pressure detected;
• detecting the volume of hydraulic fluid displaced during operation of the electromechanical actuator;
• and
• comparing the pressure detected and the volume of hydraulic fluid detected with a set volume-pressure characteristic.

A method for ventilation of a hydraulic simulator circuit of an electrohydraulic vehicle brake system, comprising a hydraulic simulator circuit for generation of a pedal response force, a first cylinder-piston device, an electromechanical actuator acting on the first cylinder-piston device for generation of a hydraulic pressure in at least one brake circuit, a first fluid path having a first valve unit arranged therein for a selective fluidic connection of the first cylinder-piston device to the simulator circuit and a second fluid path having a second valve unit arranged therein for the selective fluidic connection of the hydraulic simulator circuit to an unpressurised hydraulic fluid reservoir, wherein the method comprises the following steps:

• opening of the first valve unit in order to connect the first cylinder-piston device fluidically to the simulator circuit;
• opening of the second valve unit in order to connect the simulator circuit fluidically to the hydraulic fluid reservoir if the second valve unit was in a closed state;
• operating the electromechanical actuator to displace hydraulic fluid from the first cylinder-piston device via the simulator circuit into the hydraulic fluid reservoir;
• the method further comprising one of the following:
• wherein the vehicle brake system comprises at least one brake circuit that can be connected fluidically to the first cylinder-piston device and at least a third valve unit arranged in the at least one brake circuit, further comprising the step of:
• switching of the third valve unit from an open state to a closed state before the actuator is operated;
• or
• wherein the vehicle brake system comprises at least one brake circuit that can be connected fluidically to the first cylinder-piston device and at least a third valve unit arranged in the at least one brake circuit, wherein the third valve unit assumes an open state on operation of the electromechanical actuator, in order to convey hydraulic fluid into the at least one brake circuit, further comprising the step of:
• opening the first valve unit in order to let the hydraulic fluid stored in the brake circuits flow via the simulator circuit into the fluid reservoir.