Provided is a vehicular brake apparatus capable of suppressing the occurrence of pedal shock. In this vehicular brake apparatus, a master cylinder forms a second hydraulic chamber neighboring to a first hydraulic chamber through a seal member. The seal member is arranged at a position facing the first hydraulic chamber and the second hydraulic chamber to be movable in the axial direction relative to the master cylinder. A first hydraulic pressure generating portion executes a movement restriction hydraulic pressure control such that when the operation information obtained by the operation information obtaining portion indicates that the brake operating member is not operated, the first hydraulic pressure which is higher than the second hydraulic pressure is generated in advance and consecutively, the larger a value relating to an operating amount in the operation information obtained by the operation information obtaining portion, the higher the first hydraulic pressure is generated.

An abnormality detection device includes a control target hydraulic pressure calculating portion that calculates a control target hydraulic pressure according to an operation state of a brake pedal, the hydraulic pressure obtaining portion that obtains the hydraulic pressure of the operating fluid controlled to become the control target hydraulic pressure calculated by the control target hydraulic pressure calculating portion from the pressure sensor; a second determination threshold value changing portion that changes a threshold value to be closer to the control target hydraulic pressure calculated by the control target hydraulic pressure calculating portion in a stepwise manner when a state determining portion determines that the control target hydraulic pressure is in a maintaining state, and the abnormality determining portion that determines the hydraulic pressure braking force generating device is abnormal when the hydraulic pressure obtained by the hydraulic pressure obtaining portion deviates from the permissible divergence range.

A brake ECU (abnormality detection device) includes: an operating amount obtaining portion configured to obtain a measurement value of a stroke; a hydraulic pressure obtaining portion configured to obtain a measurement value of a reaction force hydraulic pressure having a mutual relationship with respect to the stroke; an operation direction determining portion configured to determine directions of operation of outputs from a stroke sensor and a pressure sensor; a failure detection range switching portion configured to switch the failure detection range for detecting failures of a hydraulic pressure braking force generating device in accordance with the direction of operation; and a failure determining portion configured to determine the failure of the hydraulic pressure braking force generating device from the failure detection range switched by the failure detection range switching portion, the measurement value of the stroke, and the measurement value of the reaction force hydraulic pressure.

An actuating device for a vehicle brake system may include a first piston-cylinder unit, the at least one working space of which is to be connected to at least one wheel brake of the vehicle via at least one hydraulic line, an electromechanical drive device and an actuating device, in particular a brake pedal. Methods for operating a vehicle brake system including such an actuating device and for diagnosing various portions of a vehicle brake system (e.g., but not limited to, a feed valve or a travel simulator) are also presented.

A brake system for motor vehicles may have a main brake cylinder with a floating piston arranged therein, which hermetically seals first and second pressure chambers from one another. The first pressure chamber may be hydraulically connected to a first brake circuit, and the second pressure chamber may be hydraulically connected to a second brake circuit. The brake system may further include a pressure means reservoir under atmospheric pressure, wheel brakes, an electrically controllable pressure supply device for pressure build-up and pressure reduction in the wheel brakes, a valve block with a currentless open inlet valve/switching valve for each wheel brake and with at least one outlet valve, wherein each wheel brake can be hydraulically connected via the switching valve associated with it to a pressure chamber of the main brake cylinder.

The hydraulic pressure generating device includes a regulator (spool valve) formed by a cylinder body, a spool which slidably moves within the cylinder body, a pilot chamber in which a pilot pressure which is a hydraulic pressure moving the spool along in an axial direction is inputted and an output chamber out of which an output pressure which is a hydraulic pressure corresponding to the pilot pressure is outputted, wherein the hydraulic pressure generating device further includes a spool position obtaining portion which obtains a relative position of the spool relative to the cylinder body and a pilot pressure controlling portion which controls the pilot pressure based on the relative position obtained by the spool position obtaining portion.

A recess is formed in a rear portion of a pressurizing piston, and a small-diameter rod is formed in a front portion of an input piston. A sleeve is disposed inside the recess, and the small-diameter rod is liquid-tightly and slidably fitted to the sleeve. A space between the small-diameter rod and the recess serves as a volume chamber, which is held in communication with a reservoir. The input piston and the pressurizing piston are slidably fitted to each other via the sleeve. Therefore, the generation of a frictional force between the input piston and the pressurizing piston can be made unlikely, and the pressurizing piston can be favorably prevented from advancing as the input piston advances.

An electro-hydraulic motor vehicle brake system is provided, having a first cylinder-piston device, which can be fluidically coupled to at least one wheel brake of the brake system, for generating hydraulic pressure on the at least one wheel brake, wherein the first cylinder-piston device comprises at least one first piston. The brake system further has a second cylinder-piston device, which comprises at least one second piston, and an electromechanical actuator which acts on the second piston of the second cylinder-piston device. The second cylinder-piston device is or can be fluidically coupled at the output side to the first piston of the first cylinder-piston device in order to provide a hydraulic pressure, which is generated in the second cylinder-piston device upon actuation of the electromechanical actuator, for actuating the at least one first piston of the first cylinder-piston device.

The invention relates to a technique for boosting the brake force of an electrohydraulic motor vehicle brake system in a mode in which, as a result of a mechanical push-through, an actuating force onto a brake pedal acts upon a master cylinder of the brake system. According to an aspect of this technique, the method comprises the steps of: determining a value of a first variable indicating a current deceleration of the vehicle; determining, based on the first variable, a value of a second variable indicating the actuating force; determining, based on the second variable, a required brake boost; and controlling an electromechanical actuator acting upon the master brake cylinder to obtain the required brake boost.

The invention relates to a technique for operating an electrohydraulic motor vehicle brake system comprising a master cylinder (or any other cylinder-piston arrangement) that can be supplied with a hydraulic fluid from a reservoir, an electromechanical actuator for actuating a piston accommodated in the master cylinder, a wheel brake that can be coupled to the master cylinder, and a stop valve provided between the master cylinder and the wheel brake. According to an aspect of this technique, the method comprises the steps of: controlling the electromechanical actuator to build up hydraulic pressure on the wheel brake; controlling the stop valve to hold the hydraulic pressure already built up on the wheel brake; controlling the electromechanical actuator to take in hydraulic fluid from the reservoir while monitoring a time response of a pressure drop in the master cylinder associated with the take-in; and interrupting the take-in depending on a result of the monitoring.