Fluid-pressure and analogous brake systems – Multiple fluid-receiving devices – Multiple motors
Patent
1996-02-13
1997-12-30
Oberleitner, Robert J.
Fluid-pressure and analogous brake systems
Multiple fluid-receiving devices
Multiple motors
B60T 1300
Patent
active
057021635
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The invention pertains to a method and an apparatus for controlling a brake system of a vehicle wherein braking action is effected as a function of the driver's command and the application pressures.
A method and apparatus of this type are known from, for example, DE 41 12 845 A1. In the electrically controlled brake system described in that document, the application pressure of the individual wheel brakes and thus the onset of braking are determined by evaluation of the change in pressure over time during a brake actuation process. This application pressure serves to correct a nominal pressure derived from the driver's command, and the corrected nominal pressure is used to control the supply of pressure medium being sent to the individual wheel brakes. The correction is carried out with the goal of producing a uniform braking force at all the wheels of the vehicle or at all the wheels of one axle of the vehicle. As a result, influences such as wear, variations in the coefficient of friction, mechanical losses, and tolerances at the individual wheel brakes are compensated. In addition, through the determination of the application pressures, the simultaneous response of the individual wheel brakes is guaranteed, so that the bumping forces between the tractor and the trailer are reduced. The braking reaction, the braking action, and the onset of the braking action are determined on the basis of parameters of the brake system itself. This can be unsatisfactory in a concrete case.
The task of the invention is to provide measures for improving the detection the of braking reaction, of the braking action, and of the onset of the braking action.
This is achieved by means of the characterizing features of the independent claims.
It is known from EP 149 137 A2 that a signal corresponding to the static axle load can be detected and that this can be used by a braking force control system to distribute the brake pressures.
EP 276 435 describes an electrically controlled brake system in which the braking moment is determined and evaluated.
SUMMARY OF THE INVENTION
According to the invention, the onset of braking action is determined from the reaction of the vehicle body during braking.
The process according to the invention makes it possible to detect the braking action and the onset of the braking action. As a result, an electrical-pneumatic or electrical-hydraulic or purely electrical brake system can be controlled more effectively.
It is especially advantageous that the values of the supporting forces or axle loads determined by means of the process according to the invention can be used to help distribute the brake pressures.
It is also of particular advantage that, on the basis of the values thus determined, the braking moments applied at the individual wheels can be calculated.
It is also advantageous that the process according to the invention makes it possible to monitor the brake system.
As a result of the process according to the invention, the brakes are synchronized with each other in such a way that the wear behavior and the bumping forces between the tractor and the trailer are significantly decreased. Defective synchronizations carried out mechanically are also corrected during the course of vehicle operation by means of the automatic synchronization of the brake system.
Additional advantages can be derived from the following description of exemplary embodiments and from the dependent claims.
BRIEF DESCRIPTION OF THE DRAWING
The invention is explained in greater detail below on the basis of the exemplary embodiments illustrated in the drawing.
FIG. 1 shows an overall block circuit diagram of an electrically controlled brake system;
FIG. 2 shows various alternatives for detecting the supporting forces at a wheel;
FIG. 3 shows the change in the brake pressure and in the supporting forces versus time during braking;
FIG. 4 shows the correlation between the supporting forces and the brake pressure; and
FIG. 5, finally, shows a flow chart which illustrates how the braking action and th
REFERENCES:
patent: 4560210 (1985-12-01), Tami
patent: 4606586 (1986-08-01), Eckert
patent: 4677557 (1987-06-01), Stumpe
Bartz C. T.
Oberleitner Robert J.
Robert & Bosch GmbH
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