A brake device includes a master cylinder, a braking mechanism for braking a wheel of a vehicle, a hydraulic pressure circuit coupling the master cylinder to the braking mechanism, and a reservoir tank storing a hydraulic fluid of the master cylinder. The master cylinder includes a housing, a piston, and a seal member. The piston changes a hydraulic pressure of the hydraulic fluid in a hydraulic pressure chamber in the housing. The seal member is moved with the piston to seal a gap between the housing and the piston. First to third positions are positioned in sequence in a moving direction of the piston. A replenishing hole of the housing communicates with the hydraulic pressure chamber when the piston is at the first position. The seal member closes the replenishing hole when the piston is at the second position. The hydraulic pressure of the hydraulic fluid is made negative with the seal member closing the replenishing hole when the piston is at the third position.

A brake device includes a master cylinder, a braking mechanism for braking a wheel of a vehicle, a hydraulic pressure circuit coupling the master cylinder to the braking mechanism, and a reservoir tank storing a hydraulic fluid of the master cylinder. The master cylinder includes a housing, a piston, and a seal member. The piston changes a hydraulic pressure of the hydraulic fluid in a hydraulic pressure chamber in the housing. The seal member is moved with the piston to seal a gap between the housing and the piston. First to third positions are positioned in sequence in a moving direction of the piston. A replenishing hole of the housing communicates with the hydraulic pressure chamber when the piston is at the first position. The seal member closes the replenishing hole when the piston is at the second position. The hydraulic pressure of the hydraulic fluid is made negative with the seal member closing the replenishing hole when the piston is at the third position.

A piston actuation device for the supply of a pressure medium in a pressure medium circuit of a brake system of a motor vehicle. A piston actuation device includes a piston actuable by a spindle drive to execute a back-and-forth translation movement in the direction of a piston guidance axis. The spindle drive has a spindle nut and a spindle that cooperates with the spindle nut via a screw drive. The screw drive converts a rotation movement of the spindle nut into a translation movement of the spindle in the direction of a spindle movement axis. To transmit the translation movement to the piston, the piston and the spindle are connected to each other in an axially fixed manner. The axially fixed connection between the piston and the spindle includes an articulated joint, which allows for a concentricity deviation between the piston guidance axis and the spindle movement axis.

A piston actuation device for the supply of a pressure medium in a pressure medium circuit of a brake system of a motor vehicle. A piston actuation device includes a piston actuable by a spindle drive to execute a back-and-forth translation movement in the direction of a piston guidance axis. The spindle drive has a spindle nut and a spindle that cooperates with the spindle nut via a screw drive. The screw drive converts a rotation movement of the spindle nut into a translation movement of the spindle in the direction of a spindle movement axis. To transmit the translation movement to the piston, the piston and the spindle are connected to each other in an axially fixed manner. The axially fixed connection between the piston and the spindle includes an articulated joint, which allows for a concentricity deviation between the piston guidance axis and the spindle movement axis.

A hydraulic adjustment unit of a brake system in a vehicle includes a first fluid reservoir (29), a second fluid reservoir (2), a first oil return pipe (110), and a second oil return pipe (120). The first oil return pipe (110) is connected to wheel cylinders (151, 152) of a vehicle, so that brake fluid in the wheel cylinders (151, 152) of the vehicle is delivered to the first fluid reservoir (29), to depressurize wheels of the vehicle. The second oil return pipe (120) is configured to connect to the wheel cylinders (151, 152) of the vehicle through oil inlet pipes (130, 140) of a brake system, so that the brake fluid in the wheel cylinders (151, 152) of the vehicle is delivered to the second fluid reservoir (2) through the oil inlet pipes (130, 140) of the brake system, to depressurize the wheels of the vehicle.

A hydraulic adjustment unit of a brake system in a vehicle includes a first fluid reservoir (29), a second fluid reservoir (2), a first oil return pipe (110), and a second oil return pipe (120). The first oil return pipe (110) is connected to wheel cylinders (151, 152) of a vehicle, so that brake fluid in the wheel cylinders (151, 152) of the vehicle is delivered to the first fluid reservoir (29), to depressurize wheels of the vehicle. The second oil return pipe (120) is configured to connect to the wheel cylinders (151, 152) of the vehicle through oil inlet pipes (130, 140) of a brake system, so that the brake fluid in the wheel cylinders (151, 152) of the vehicle is delivered to the second fluid reservoir (2) through the oil inlet pipes (130, 140) of the brake system, to depressurize the wheels of the vehicle.

A master cylinder includes: an input piston that is caused to advance by operating a brake operating member; a pressure piston that is provided coaxially with the input piston in order to increase a fluid pressure in a frontward pressure chamber while advancing; and a multistage modification device that varies a relationship between a stroke of the input piston and the fluid pressure in the pressure chamber in three or more stages while the input piston moves from a retreat end position to an advancement end position.

A master cylinder includes: an input piston that is caused to advance by operating a brake operating member; a pressure piston that is provided coaxially with the input piston in order to increase a fluid pressure in a frontward pressure chamber while advancing; and a multistage modification device that varies a relationship between a stroke of the input piston and the fluid pressure in the pressure chamber in three or more stages while the input piston moves from a retreat end position to an advancement end position.

A pressure supply device is provided for a hydraulic braking system of a vehicle including a first pressure chamber and a second pressure chamber, which are delimited by at least one piston of the pressure supply device, a motor and a gear unit, with the aid of which the at least one piston is displaceable at least in a first direction with the aid of an operation of the motor, an exceeding of a predefined maximum pressure difference between a chamber pressure present in the first pressure chamber and a reservoir pressure present in the brake fluid reservoir being preventable with the aid of a reservoir isolating valve, which is connectable to a brake fluid reservoir of the braking system, hydraulically connected to the first pressure chamber via an opening of the reservoir isolating valve. Also described here is a hydraulic braking system for a vehicle. In addition, a method is provided for operating a hydraulic braking system of a vehicle.

A pressure supply device is provided for a hydraulic braking system of a vehicle including a first pressure chamber and a second pressure chamber, which are delimited by at least one piston of the pressure supply device, a motor and a gear unit, with the aid of which the at least one piston is displaceable at least in a first direction with the aid of an operation of the motor, an exceeding of a predefined maximum pressure difference between a chamber pressure present in the first pressure chamber and a reservoir pressure present in the brake fluid reservoir being preventable with the aid of a reservoir isolating valve, which is connectable to a brake fluid reservoir of the braking system, hydraulically connected to the first pressure chamber via an opening of the reservoir isolating valve. Also described here is a hydraulic braking system for a vehicle. In addition, a method is provided for operating a hydraulic braking system of a vehicle.