Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1996-01-05
1998-06-30
Young, Lee W.
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
303125, 60545, B60T 234
Patent
active
057722900
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a vehicle brake system having an electronically adjustable brake booster.
The demand on vehicle brake systems having brake boosters is to optimally perform a braking operation initiated by the driver even if the driver's behavior is not always commensurate with the respective situation involved. To this end, electromagnetically actuated control means for additional air were provided which were activated in response to the actuation dynamics of the brake pedal (cf. the previously filed and post-published German patent applications P 42 17 409 and P 43 09 850 of the applicant).
In the case of an emergency braking, when the braking operation is enhanced by a brake booster, the boosting operation has been increased to an extent as allowed by the pressure differential in the individual chambers of the brake booster. The actuation velocity of the brake pedal was used as the triggering criterion. As soon as a given threshold value of the actuation velocity was surpassed, the maximally possible amplification of the brake boosting operation was initiated. Although this operation results in a considerably shortened brake path, the driver is deprived of the control of the braking operation in that a once initiated full braking proceeds entirely automatically, in other words the driver is no longer in a position to intervene in the braking operation. It is however desirable to stop full braking or emergency braking operations by an intervention on the part of the driver, for instance when the danger does not exist anymore.
DE-OS 39 02 215 discloses a vacuum brake booster in which a contact switch is provided in the region of movement of the valve piston in the control valve housing. The first contact of the contact switch is a metallic ring seated in a recess in the control valve housing. The second contact of the contact switch is the valve piston itself, in which an axially slidable metallic contact member is guided in a guide sleeve of insulating material which is arranged in a ring, and is biased by means of a pressure spring and establishes an electrical connection between the ring and the valve piston. A valve is connected to two contact elements provided in the control valve housing, in which the contact element cooperating with the valve piston is biased against the valve piston by means of a pressure spring. The pressure spring is always loaded so that the connection between the operating chamber of the brake booster and the source of vacuum is free. Upon actuation, the valve member becomes detached from the ring such that the power supply to the valve and consequently also the connection between the operating chamber and the source of vacuum is interrupted.
EP 0 327 276 specifies a brake booster in which a switch device is disposed besides a valve element for actuating brake warning lights, and an abutment element is carried by the valve element, said switch device being actuated in response to a movement of the abutment element with the valve element. The assembly containing the switch device is fixed to a housing of the brake booster which contains the servo piston.
DE 33 46 140 describes a vacuum brake booster in which a piston rod operable by a brake pedal is connected to a control valve piston which, via a reaction disk, acts on a pressure rod that is connected to the master cylinder. The reaction disk is received in a stepped bore and the free end of the control valve piston is provided with a pedal received in a stepped portion which limits the axial movability of the control valve piston.
EP 0 379 329 discloses a brake booster in which a switch having two touch contacts is provided in the housing of the brake booster. An actuating member axially displaced by a brake pedal includes a laterally protruding bar which is adapted to bridge the two contacts and thus close a circuit.
Based on the above, the problem underlying the present invention is to provide an apparatus by which a driver-initiated sudden stopping of an emergency braking operation is determined safely and free of in
REFERENCES:
patent: 5372409 (1994-12-01), Farr
patent: 5556173 (1996-09-01), Steiner et al.
Dieringer Werner
Heibel Helmut
Kohrt Jens-Peter
Michels Erwin
Mohr Kurt
Lucas Industries Public Limited Company
Young Lee W.
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