Lucas Industries Public Limited Company

Lucas Industries Limited

Lucas Automotive Gmbh

Other

Christoph Linden

Gregor Godlewsky

Lorenz Maack

Lothar Zeuner

Michael Keller

A hydraulic pressure generator for a vehicle brake system comprises a piston and a cylinder that movably accommodates the piston. The piston defines a first hydraulic chamber and a second hydraulic chamber in the cylinder on opposite piston sides, wherein each hydraulic chamber has a hydraulic inlet and a hydraulic outlet. An actuating unit is able to put the piston into a back-and-forth motion so that an intake stroke with regard to the first hydraulic chamber corresponds to a discharge stroke with regard to the second hydraulic chamber, and vice versa.

Hydraulic pressure generator for a vehicle brake system, vehicle brake system having such a hydraulic pressure generator, and method for operating the hydraulic pressure generator

The invention relates to a method for establishing the position of an actuating unit which is operated by an electric motor, in which a motor speed is determined from a motor model, the speed is integrated over a period of time and the position of the actuating unit is determined by multiplying the result of the integration by a proportionality factor. The motor model takes account of afterrunning of the electric motor at the instant of switch-off. The invention also relates to actuating units, brakes, pumps and transmissions for which the method can be used.

Sensorless measurement of positioning travel, especially on an electromotively operated parking brake

Electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from one another by a moveable wall, a control valve arrangement, which can be actuated by means of an electromagnetic actuating device and via which a pressure difference between the pressure and the vacuum chamber can be set, wherein the control valve arrangement takes up a holding position, a pressure build-up position, a pressure reduction position in accordance with a current generated as correcting variable by an electronic control unit and flowing through the electromagnetic actuating device, a cylinder-piston arrangement, which is connected to the brake booster and comprises a piston, coupled to a brake pedal, of a hydraulic cylinder which has a hydraulic connection leading to a wheel brake, a sensor arrangement for detecting a signal which is correlated with the pressure of the hydraulic cylinder and which reproduces the controlled variable, wherein the electronic control unit establishes a command variable, taking account of the output signal of a sensor arrangement detecting the driver's braking requirement, and wherein the value of the correcting variable remains unchanged with respect to a value output directly beforehand if the control difference established from the command variable and the controlled variable does not deviate from a first predetermined tolerance range value.

Electronically controllable brake booster

The invention utilizes the finding that a pressure variation or pressure difference between two chambers of a brake booster is a parameter of considerable influence on the behavior of a brake booster control valve arrangement in the operation of the brake booster. Starting from a holding position for the control valve arrangement, pressure levels related to changeovers from the holding position to a first pressure changing position and a second pressure changing position, respectively, are determined. Depending on the thus determined pressure level differences, current values for an actuation of the control valve arrangement defining upper and lower limits for the holding position are adjusted.

In an electronically controllable brake booster a value is sensed which is characteristic for the actual pressure characteristic in the pressure chamber. The actual pressure characteristic is checked for the existence of periodic oscillation components of a predetermined frequency band with a predetermined minimum amplitude. Upon the existence of such periodic oscillation components, the current flowing through an electromagnetic actuator for a control valve arrangement of the brake booster is decreased by a first predetermined value for a first pressure changing position. Further, the current for a second pressure changing position is decreased by second predetermined value.

The invention relates to an electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from each other by a movable wall, a control valve arrangement which can be actuated by means of an electromagnetic actuation means, and by means of which a pressure difference between the pressure chamber and the vacuum chamber can be adjusted, with the control valve arrangement, as a function of a current flowing through the electromagnetic actuation means, assuming a holding position in which the current ranges between a higher value and a lower value without the control valve arrangement leaving the holding position, a first pressure changing position in which the current is higher than the higher value, and a second pressure changing position in which the current is lower than the low value, characterized in that upon a changeover of the control valve arrangement from the holding position into the first or the second pressure changing position, or upon a changeover from the first or the second pressure changing position into the holding position, the time period is determined which is required for the changeover, the determined time period is compared with a predetermined time interval in order to determine whether the changeover has taken place within this predetermined time interval, and the higher and/or lower current value defining the holding position is modified for future changeovers if the determined time period exceeds the predetermined time interval.

A pneumatic brake booster (,) has a booster housing (,), the interior of which is subdivided by at least one movable wall (,) into a vacuum chamber (,) and a working chamber (,). Projecting into the booster housing (,) is a control valve (,) which, after a response force acting counter to its operating direction has been overcome, controls a pneumatic pressure difference acting upon the movable wall (,). The control valve (,) is operable both by means of a mechanical input element (,) and, independently thereof, by means of an electromagnetic arrangement (,) comprising a coil (,) and an armature (,), which are displaceable relative to one another along the operating direction. To reduce the response force which has to be overcome by a user, a device for detecting an operation of the control valve (,) effected by means of the mechanical input element (,) is provided which, once such an operation has been detected, during said operation prompts an energizing of the electromagnetic arrangement (,) of an intensity sufficient to reduce the response force of the control valve (,) yet not increase the braking force provided by the brake booster in accordance with the operation.

Pneumatic brake booster with reduced response force

The invention relates to a vehicle brake system of a motor vehicle, with an electronically controllable brake booster, comprising a vacuum chamber and a pressure chamber which are separated from each other by a movable wall, a control valve arrangement which can be actuated by an electro-magnetic actuator, wherein a pressure difference between the pressure chamber and the vacuum chamber is adjustable, with the movable wall changing its position as a function of the pressure conditions in the vacuum chamber and in the pressure chamber, thereby actuating a master cylinder, with the electromagnetic being supplied with current signals by an electronic control unit during operation, which the electronic control unit generates as a function of driving dynamics conditions or external influences, characterised in that upon the presence of certain driving dynamics conditions or external influences, or combinations thereof which render the actuation of the master cylinder necessary with a predetermined probability within a predetermined time interval, the electronic control unit generates control signals for the electromagnetic actuation means, so that the control valve arrangement is actuated to such a degree that play, backlash, or tolerance-related free travel in at least part of the vehicle brake system is overcome.

Vehicle brake system of a motor vehicle

An electronically controllable brake booster with a vacuum chamber and a pressure chamber, which are separated from each other by a movable wall, a control valve arrangement which can be actuated by an electromagnetic actuation device, through which a pressure difference between the pressure chamber and the vacuum chamber can be adjusted, with the control valve arrangement, as a function of a current flowing through the electromagnetic actuation device, assuming a holding position in which the current ranges between a higher value and a lower value without the control valve arrangement leaving the holding position, a first pressure changing position in which the current is higher than the higher value, and a second pressure changing position in which the current is lower than the low value, characterised in that upon a changeover of the control valve arrangement from the holding position into the first or the second pressure changing position, or upon a changeover from the first or the second pressure changing position into the holding position, the current value is sensed at which the respective changeover actually takes place, and this sensed current value is utilised for the specification of the higher value or the lower value, respectively, of the currents defining the holding position for a future corresponding changeover of the control valve arrangement.

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Vallendar, Germany

Christoph Linden