A pneumatic brake booster having a booster housing. The booster housing has at least two thin-walled shell elements and an elastomer sealing element. The sealing element has a sealing bead, which is of encircling form radially at the outside, and at least one rolling diaphragm portion which adjoins the sealing bead. The sealing bead is sealingly clamped in a clamping space between the shell elements. The clamping space is formed by walls which are generated in the shell elements by deformation, its radial inner wall formed by a tubular, axially forwardly extending projection, which is folded at its front edge, of the second shell element. It is proposed that a bead-side rear wall of the clamping space is formed by an encircling, radially outwardly projecting collar which is formed on the second shell element.

A pre-filling device for a braking system. The pre-filling device includes a pre-filling channel, a pre-filling pressure being inside the channel when the braking system is in a rest and hydro-boost position, and a mechanical valve configured to be opened following a transition from the rest and hydro-boost position to a working position of the braking system; and a hydraulic valve cooperating with the mechanical valve setting the pre-filling pressure inside the channel. The hydraulic valve includes in a first area, facing the mechanical valve, a hole communicating with the channel, and in a second area, hydraulically isolated from the first area, a preloaded resilient element in a chamber held at atmospheric pressure. The hydraulic valve is configured to be connected or not to be connected, by a reciprocating movement inside the channel, to a hydro-booster device and to keep a predetermined pre-filling pressure upon varying of the hydro-boost pressure.

The vehicle braking device includes a pilot pressure control portion which executes normal control in which the pilot pressure is controlled in response to the target value of the servo pressure and shortening control in which the change amount of the pilot pressure per unit time is greater than the change amount under the normal control in a mutually different timing, a state judging portion which judges the state of the master piston relating hysteresis of sliding resistance of the master piston based on the detection result of the servo pressure detecting portion or the liquid pressure co-relating with the servo premeasure and a control switching over portion which terminates the shortening control based on the detection result of the servo pressure detecting portion and the detection result of the state judging portion.

A master brake cylinder is described for a brake system of a motor vehicle as having a hydraulic cylinder that has a plurality of hydraulic connections, in which at least one hydraulic piston is mounted so as to be displaceable axially in a direction of actuation and in a relief direction, the hydraulic piston being displaceable against the force of a spring element in the direction of actuation, the hydraulic piston having at least one lateral wall opening that, in at least one sliding position, opens into an inner chamber of the hydraulic cylinder. It is provided that the lateral wall opening is assigned an elastically deformable sealing ring that on its inner side is fastened on the hydraulic piston and on its outer side is pre-loaded against the hydraulic cylinder by its inherent elasticity and is shaped such that when the hydraulic piston is displaced in the direction of actuation it detaches from the hydraulic cylinder, and when the hydraulic piston is displaced in the relief direction it bears on the hydraulic cylinder.

A method for operating a hydraulic brake system of a motor vehicle includes checking a functional capability of the brake system by detecting a plurality of idle travel values of an actuator before the actuator generates a clamping force, and comparing the idle travel values with a plurality of expected idle travel values of the actuator that are determined as a function of an actuation of a pressure generator. The brake system includes a wheel brake having a brake piston, a brake pedal device, the pressure generator configured to generate a pressure generator force that moves the brake piston in order to active the wheel brake, and the actuator assigned to the wheel brake and configured to generate an actuator force that moves the brake piston in order to activate the wheel brake. The pressure generator and the actuator are actuated such that together they generate a total clamping force.

In an application, which refers to holding actuation of a parking brake mechanism (a rotation-linear motion conversion mechanism), a braking control apparatus (a parking brake control apparatus) determines an application stroke from a load detection point including as far as an overshoot amount. The load detection point is a generation point of a thrust force that is detected due to a current flowing in the electric motor. The overshoot amount is generated based on a rotation of an electric motor due to inertia after driving of the electric motor is stopped. The braking control apparatus determines a target release stroke in a release, which is release actuation of the parking brake mechanism, according to the application stroke. The braking control apparatus outputs a control instruction to conduct the release based on the target release stroke.

A brake system may include an actuating device, in particular a brake pedal; a first piston-cylinder unit having two pistons subjecting the brake circuits to a pressure medium via a valve device, wherein one of the pistons can be actuated by the actuation device; a second piston-cylinder unit having an electric motor drive, a transmission at least one piston to supply at least one of the brake circuits with a pressure medium via a valve device; and a motor pump unit with a valve device to supply the brake circuits with a pressure medium. The brake system may also include a hydraulic travel simulator with a pressure or working chamber which is connected to the first piston-cylinder unit.

A brake system may include an actuation device, in particular a brake pedal, a first piston-cylinder unit with two pistons, in particular an auxiliary piston and a second piston, in order to supply a pressure medium to brake circuits via a valve device. One of the pistons, in particular the auxiliary piston, can be actuated by means of the actuation device. The brake system may further include a second piston-cylinder unit with an electric motor-powered drive, a transmission, and at least one piston to supply a pressure medium to at least one of the brake circuits via a valve device and a motor-pump unit with a valve device to supply a pressure medium to the brake circuits. According to one aspect, a hydraulic travel simulator is connected to a pressure or working chamber of the first piston-cylinder unit.

A vehicle braking system includes a first wheel cylinder, a second wheel cylinder, a master cylinder including a first master cylinder chamber in fluid communication with the first wheel cylinder via a first circuit and a second master cylinder chamber in fluid communication with the second wheel cylinder via a second circuit, and an electronically controlled pressure generating unit separate from the master cylinder. The vehicle braking system is operable to provide braking in a first configuration in which the electronically controlled pressure generating unit pressurizes fluid, through the master cylinder, in the first circuit, to the first wheel cylinder. In the first configuration, the electronically controlled pressure generating unit pressurizes fluid in the second circuit to the second wheel cylinder, bypassing the master cylinder.

A brake system may include an actuating device, in particular a brake pedal; a first piston-cylinder unit having two pistons subjecting the brake circuits to a pressure medium via a valve device, wherein one of the pistons can be actuated by the actuation device; a second piston-cylinder unit having an electric motor drive, a transmission at least one piston to supply at least one of the brake circuits with a pressure medium via a valve device; and a motor pump unit with a valve device to supply the brake circuits with a pressure medium. The brake system may also include a hydraulic travel simulator with a pressure or working chamber which is connected to the first piston-cylinder unit.