Brakes – Operators – Electric
Reexamination Certificate
1999-06-11
2001-05-29
Schwartz, Christopher P. (Department: 3613)
Brakes
Operators
Electric
C188S00111E, C188S00111E, C303S020000
Reexamination Certificate
active
06237729
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for controlling a vehicle braking system.
BACKGROUND INFORMATION
It is desirable to adjust the air gap on a wheel brake in view of the brake lining wear that is always present, and changes in boundary conditions, for example the brake temperature. This applies in particular to an electrically motor-driven wheel brake system on motor vehicles, in which the wheel brakes are actuated by activating electric-motor brake positioners. In these braking systems the air gap must be adjusted actively, i.e., by activating the brake positioner. Electrically motor-driven wheel brakes for motor vehicles are known, for example from PCT Publication No. 94/24453, where the application force is generated by an electric motor. In an electrically controlled braking system, a requisite air gap (spacing between the brake lining and brake disk or drum) should be maintained in the unbraked state at all operating points.
Important factors regarding the air gap are on the one hand that a small air gap is desirable in order to minimize the time necessary for application of the brake linings, while on the other hand a larger air gap is necessary so that in the unbraked state, frictional losses do not occur between the brake disk and brake lining in any operating situation, even, for example, in the event of impact on the brake disk or, because of the elasticity of the suspension system (steering knuckles, etc.) on poor road surfaces.
SUMMARY OF THE INVENTION
It is an object of the present invention to meet the various needs in terms of air gap adjustment set forth above.
The approach described below takes into account the various demands on the air gap adjustment system, especially in terms of absence of friction when the vehicle is not being braked, and the dynamics of a braking action.
It is particularly advantageous that the air gap is actively increased when predefined conditions exist. These conditions indicate that the probability of an immediately imminent braking operation is no greater than an average probability. In an operating state in which it must be assumed, with high probability, that a braking operation is immediately imminent, a smaller air gap is set.
An application in systems in which the air gap can be actively adjusted, for example in electric-motor braking systems, is particularly advantageous.
Advantageously, the service life of the brake disk and the brake lining, or of the brake drum and brake shoe, are extended.
In addition, the reduction in the residual torque on the vehicle wheel yields a reduction in the vehicle's fuel consumption.
It is furthermore particularly advantageous that the expanded air gap is dynamically decreased very quickly in the event of a braking requirement, by the fact that the wheel brake adjusting device is displaced with almost maximum dynamics, the control method advantageously differing from the control method in the case of a braking operation.
REFERENCES:
patent: 5125483 (1992-06-01), Kitagawa et al.
patent: 5366280 (1994-11-01), Littlejohn
patent: 5722744 (1998-03-01), Kupfer et al.
patent: 5829845 (1998-11-01), Maron et al.
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patent: 5954407 (1999-09-01), Schramm et al.
patent: 5984433 (1999-11-01), Stumpe et al.
patent: 6000507 (1999-12-01), Böhm et al.
patent: 6008604 (1999-12-01), Maisch
patent: 6040665 (2000-03-01), Shirai et al.
patent: WO 94/24453 (1994-10-01), None
Kenyon & Kenyon
Robert & Bosch GmbH
Schwartz Christopher P.
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