Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1997-04-18
2001-06-05
Graham, Matthew C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303SDIG004
Reexamination Certificate
active
06241323
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method and an apparatus for regulating brake pressure based on the inlet pressure set by the driver.
A method and an apparatus for controlling the brake system of a vehicle is disclosed in the unpublished German Patent Application 1 95 01 760.1 of Jan. 21, 1995. In it the braking force at the wheel brakes is controlled, at least in certain operating conditions, by an active braking force increase or decrease according to the driver's wish. The derivation of the driver's wish from the force applied at the brake pedal would be desirable. In the prior-art system the force applied is determined by measuring the inlet pressure (pressure in the main brake cylinder). This does not coincide in every operating situation with the force actually applied by the foot.
It is the object of the invention to improve the detection of the driver's brake demand by measuring the inlet pressure.
SUMMARY OF THE INVENTION
According to the invention, a brake pressure representing a desired braking action (driver's wish value) is determined based on the measured inlet pressure and additional parameters available for the system. According to a first embodiment these parameters are status information for pressure producing means, such as a return pump, and at least one valve between a main brake cylinder and the inlet or outlet of the pressure producing means. A pressure gradient dP
VOR
/dt may also be considered. According to a second embodiment the system parameters comprise at least one flow rate in the system, for example the volume change &Dgr;V
HZ
in the master cylinder, and the derivative dP/dv at pressure P
VOR
.
The method and apparatus of the invention offers an improved derivation of the driver's wish from the measured inlet pressure in the main brake cylinder of a hydraulic brake system. The more exact detection of the driver's wish improves the operation of the control of the brake system.
It is especially advantageous to undertake a correction of the inlet pressure in accord with the operating states of the valves and pump(s) of the brake system, since particularly the operating state of the pump(s) and of the valves of the brake system has a strong influence on the inlet pressure.
A further improvement of accuracy is achieved by correcting the measured inlet pressure by taking into consideration the volumes flowing through the valves and pump(s) of the brake system.
Especially advantageous is the use of the method and apparatus of invention in the case of a so-called brake aid, in which the braking force in specific situations is intensified dependent upon the driver's braking wish.
Also advantageous is the use of the invention in all of those control systems for brake systems in which the driver's braking wish is detected at least by means of the pressure in the master cylinder of the brake system.
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Wagner Jochen
Wiss Helmut
Fulbright & Jaworski LLP
Graham Matthew C.
Robert & Bosch GmbH
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