A vehicle brake system having electronic pressure regulation and a related method, in which the system stabilizes a vehicle, supports the actuation of the brake system, and/or enables a fully/partly automated driving operation. The system has a primary actuator system that sets/regulates different brake pressures at the wheel brakes, and an electronically controllable secondary actuator system that secures the vehicle brake system against primary actuator failure. For a primary actuator error, the secondary actuator is controlled so that the secondary system produces a brake pressure that, based on the dynamic axle load displacement, occurring during a braking process, in the direction of a front axle, is greater than the brake pressure that is convertable into a rear axle wheel brake braking power. A device reduces this brake pressure at the rear axle wheel brake to a value at which the vehicle wheel, assigned to this wheel brake, does not lock.

A braking system for a vehicle includes: a front axle wheel brake cylinder; a rear axle wheel brake cylinder; and a control electronics system for controlling a first brake pressure in the front axle wheel brake cylinder and/or a second brake pressure in the rear axle wheel brake cylinder. A limiting value z-critical is defined for the braking system, which specifies a maximum braking action, at which a traction stress on the front axle of the vehicle and a traction stress on the rear axle of the vehicle are equal. The braking system is mechanically configured for a z-critical of at least 0.7 g, and the braking system is controlled by the control electronics system during operation using a z-critical value of at most 0.7 g.

Methods and systems are provided for operating a hybrid vehicle during operating conditions where vehicle braking is requested. In one example, regenerative braking is allocated to vehicle axles responsive to wheel torques of respective vehicle axles in response to an anti-lock braking system being activated. Additionally, friction braking torque is allocated to vehicle axles responsive to the anti-lock braking system being activated.

This invention is characterized in being provided with: a determining unit for determining the execution of a state transition from a pressure increase mode in which an electric pump is operated with a differential valve being in a closed state and a holding valve being in an open state to a pressure decrease mode in which the electric pump is operated with the holding valve being in a closed state and the differential valve being in an open state; and a control unit for controlling, when the determining unit determines the execution of the state transition, one or more of the differential valve, the holding valve, a pressure reduction valve, and the electric pump, and reducing the amount of a braking fluid retained in a path between the differential valve and the holding valve.

A method for controlling a vehicle deceleration in a vehicle with an ABS brake system. The method includes detecting a target vehicle deceleration specified by a driver; defining a maximum deceleration and a minimum deceleration, each depending on the detected target vehicle deceleration; detecting an actual vehicle deceleration; and controlling a braking pressure on wheel brakes of a first vehicle axle and a second vehicle axle depending on the detected actual vehicle deceleration by actuation of ABS brake valves. Controlling the braking pressure by the actuation of the ABS brake valves comprises controlling the braking pressure on the wheel brakes of the second vehicle axle depending on a detected actual differential slip if the actual vehicle deceleration is less than the maximum deceleration and greater than the minimum deceleration, wherein the actual differential slip indicates the difference in a rotational behavior of the first vehicle axle.

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 method for regulating a vehicle-actual-deceleration in a vehicle with an ABS brake system includes detecting the vehicle-actual-deceleration; determining a target vehicle deceleration and detecting at least one actual wheel rotational behavior. The method further includes calculating actuation times for actuation of pressure control valves of the ABS brake system associated with the wheels of the first vehicle axle and the wheels of the further vehicle axle and determining correction actuation times if at least one of the respective calculated actuation times is less than a minimum actuation time associated with the respective pressure control valve. Calculation of each of the respective actuation times is carried out at least for all of a first number of pressure control valves with which wheels are associated whose rotational behavior follows the at least one actual wheel rotational behavior.

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 method for adjusting brake pressures on pneumatically actuated wheel brakes of a vehicle includes, in a normal braking mode, continuously determining, by the brake control unit, at least one differential slip value as a difference between slip values of two wheels or axles of the vehicle, and determining, by the brake control unit, an interaxle braking distribution index for a relevant pair of axles by an assessment of a change in the at least one differential slip value within an evaluation interval. The method further includes, in a pressure control mode, using, by the brake control unit, the interaxle braking distribution index that is determined in the normal braking mode for the weighting of the control signals for the respective pair of axles.

The control device for a four-wheel drive vehicle includes a differential restriction control unit configured to cause the differential restriction device, which is enable a differential restriction degree between a front wheel rotary shaft and a rear wheel rotary shaft, to change the differential restriction degree and a braking control unit configured to cause the braking device to perform EBD control and ABS control. The braking control unit is configured to cause the braking device to suspend the EBD control when the ABS control is started while the EBD control is being performed, and the differential restriction control unit is configured to change the differential restriction degree to a third degree larger than a first degree and equal to or smaller than a second degree when the ABS control is started while the EBD control is being performed.