A method for operating a vehicle brake system including a brake booster and an electronic traction control device, which is used as a fallback level in a malfunction of the brake booster. The position of an accelerator pedal is ascertained when a malfunction of the brake booster is detected, and under the precondition that the accelerator pedal is released, a predefined initial pressure is built up in a pressure chamber of a master brake cylinder of the vehicle brake system with the aid of the traction control device so that a deceleration of the vehicle is induced. A control unit which is designed to carry out the method, and a vehicle having a vehicle brake system and a control unit, are also described.

A pedal-travel simulator of a hydraulic power vehicle brake system is connected to a brake-fluid reservoir by way of a groove between two piston seals of a power brake-pressure generator. Any air bubbles in the brake fluid get out of the pedal-travel simulator into the brake-fluid reservoir, and the piston seals are lubricated with the brake fluid.

The invention relates to an improved plunger assembly for a vehicle brake system. The plunger assembly is operable as a pressure source to control brake fluid pressure supplied to one or more wheel brakes. The plunger assembly comprises a housing defining a cylinder; a reversible motor supported by the housing and having a rotor; and a linear actuator such as a ball screw/nut mechanism driven by the motor. A plunger head is mounted in the cylinder and driven by the linear actuator in first and second opposite directions. Improvements include the plunger assembly engage at least one seal that defines a portion of a pressurized chamber. An end cap covers the projecting end of the cylinder and is secured to the housing to define a fluid passageway between the end of the cylinder and at least one fluid passageway provided in the housing block.

The invention relates to an improved plunger assembly for a vehicle brake system. The plunger assembly is operable as a pressure source to control brake fluid pressure supplied to one or more wheel brakes. The plunger assembly comprises a housing defining a cylinder; a reversible motor supported by the housing and having a rotor; and a linear actuator such as a ball screw/nut mechanism driven by the motor. A plunger head is mounted in the cylinder and driven by the linear actuator in first and second opposite directions. Improvements include a linear actuator rotationally supported on the housing by a bearing to actuate the plunger head connection to a ball screw.

A vehicle brake system and method for increasing the brake pressure in a first wheel brake cylinder and for limiting the brake pressure in a second wheel brake cylinder of a vehicle brake system. The method includes increasing a first brake pressure in the first wheel brake cylinder by controlling/holding a wheel inlet valve in its open state and controlling/holding a first wheel outlet valve in its closed state, and limiting an increase of a second brake pressure in the second wheel brake cylinder during the transfer of brake fluid into the first wheel brake cylinder by controlling/holding a second wheel inlet valve in its closed state and controlling a second wheel outlet valve into its open state. The second wheel outlet valve is controlled with a pulse width-modulated signal so that during the transfer of brake fluid, the second wheel outlet valve is permanently in its open state.

A control apparatus/method for operating an electromechanical brake booster of a vehicle braking system, including: applying control to an electromechanical brake booster motor in consideration at least of a braking definition signal regarding a braking input of a driver and/or automatic speed control system of the vehicle (ACC); specifying, in consideration at least of the braking definition signal, a target motor force of the electromechanical brake booster motor or a target brake application force of the electromechanical brake booster into a brake master cylinder, downstream from the electromechanical brake booster, of the braking system; and applying control to the electromechanical brake booster motor in consideration of a force difference between the specified target motor force and an estimated/measured actual motor force of the motor, or between the specified target brake application force and an estimated/measured actual brake application force of the electromechanical brake booster into the downstream brake master cylinder.

According to one embodiment, for example, when it is determined that a certain condition has been satisfied while first antilock control is being executed, a controller of a brake control apparatus executes second antilock control by opening and closing a solenoid valve with a motor stopped so that brake fluid of the wheel cylinder is caused to flow into a reservoir, the second antilock control including a second pressure reduction mode, the second pressure reduction mode reducing a pressure of a wheel cylinder while substantially equilibrating the pressure of the wheel cylinder and a pressure of the reservoir at a certain pressure or larger, the certain pressure being larger than zero.

A brake ECU automatically pressurizes a servo chamber of a master cylinder, and then determines whether a single system failure has occurred in the master system. When the single system failure is detected, a refresh drive is executed so that a fluid pressure chamber provided to the master cylinder is subjected to a negative pressure to cause a brake fluid to forcibly flow from a reservoir into the fluid pressure chamber via a seal member provided inside of the master cylinder and foreign matters caught by the seal member are thus washed out. The brake ECU again automatically pressurizes the servo chamber, determines whether the single system failure has been resolved, and notifies the occurrence of the single system failure when the single system failure has not been resolved.

A method for boosting a braking force in an electronically slip-controllable vehicle brake system, as well as an electronically slip-controllable vehicle brake system. Vehicle brake systems of this kind are at least equipped with a power brake unit and electronic slip-controllable vehicle brake system. In the case of a malfunction of the power brake unit, the traction-slip control device (92) takes over the boosting. A method for determining a composite signal which is adjusted by controlling a drive of a pressure generator of the slip-controllable vehicle brake system accordingly. To this end, an electronic control unit records two mutually independent input quantities, converts these input quantities into evaluation signals and sums the evaluation signals mathematically to yield a composite signal. The latter represents a setpoint brake pressure that the slip-controllable vehicle brake system supplies by controlling a pressure generator accordingly.

A vehicle including a coupling device that includes (a) an engagement clutch mechanism for coupling an input side engagement member that is coupled to a drive power source of the vehicle and an output side engagement member that is coupled to a drive wheel of the vehicle; and (b) a cam mechanism for assisting engagement of the input and output side engagement members depending on a differential torque by which the input and output side engagement members are rotated differentially. The vehicle includes a control device configured, when the engagement of the input and output side engagement members is to be released, to cause a braking force to be applied to one of the input and output side engagement members such that the differential torque is reduced.