Fluid-pressure and analogous brake systems – Pipeless valves
Patent
1992-09-04
1994-11-15
Oberleitner, Robert J.
Fluid-pressure and analogous brake systems
Pipeless valves
303111, 36442602, B60T 866
Patent
active
053641744
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
From DE-A1 3706 514, a method is known to determine, in a vehicle with a two-wheel drive, the reference speed for the development of a slip signal, other than by the control, through the speed of the slower of the non-driven wheels. In the event of instability, the increase of an auxiliary reference speed, which is determined, other than by the control, through the speed of the faster of the non-driven wheels, determines the reference speed.
SUMMARY OF THE INVENTION
The object of the invention is to develop a method which determines a final reference speed signal for development of a slip signal, as described above, for all-wheel drive vehicles rather than two wheel drive vehicles.
This object is achieved, according to one embodiment of the invention, in an improved method for obtaining a final reference speed signal in an anti-lock brake system having a slip control facility, for which a reference speed signal and an auxiliary reference speed signal having a time domain slope which determines characteristics of the reference speed signal in the case of instability of at least one wheel, are derived from wheel speed signals produced by a wheel sensor means for measuring the speed of a fastest, second-fastest, third-fastest, and slowest wheel, respectively, wherein when used on a vehicle with four driven wheels, the auxiliary reference speed signal is increased with the speed signal of the third-fastest wheel and decreased with the speed signal of the fastest wheel and in that, between the end of the increase and the beginning of the decrease, the auxiliary reference speed signal is held at the last speed signal value attained during the increase, and in that the reference speed signal is increased with the speed signal of the slowest wheel and decreased with the speed signal of the third-fastest wheel and in that, between the end of the increase and the beginning of the decrease, the reference speed signal is held at the last speed signal value attained during the increase and wherein the final reference speed signal corresponds to the reference speed signal.
The object is achieved, according to a further embodiment of the invention, in an improved method for obtaining a final reference speed signal in an anti-lock brake system having a slip control facility, for which a reference speed signal and an auxiliary reference speed signal having a time domain slope which determines characteristics of the reference speed signal in a case of instability of at least one wheel, are derived from wheel speed signals produced by a wheel sensor means for measuring the speed of a fastest, second-fastest, third-fastest, and slowest wheel, respectively, wherein when used on a vehicle with four driven wheels but with a rear axle decoupled from a drive during braking, the auxiliary reference speed signal is increased with the speed signal of the third-fastest wheel and decreased with the speed signal of the fastest wheel and in that, between the end of the increase and the beginning of the decrease, the auxiliary reference speed signal is held at the last speed signal value attained during the increase, and in that the reference speed signal is increased with the speed signal of the slowest wheel and decreased with the speed signal of the slowest of the wheels decoupled from the drive until a predetermined speed difference occurs between the reference speed signal and the auxiliary reference speed signal and in that the reference speed signal is then maintained parallel to the auxiliary reference speed signal at a difference corresponding to the predetermined speed difference and wherein the final reference speed signal corresponds to the reference speed signal.
All wheels are now included in forming the reference. The slip caused by the wheel speed differences during cornering is thus successfully eliminated. This slip would otherwise lead to a sensitive start of control.
The linking of the reference speed, according to another embodiment of the invention, to a faster rotating wheel, in parti
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Becker Rolf
Gutohrlein Bernd
Meissner Manfred
Michel Thomas
Muratori Alfred
Oberleitner Robert J.
Robert & Bosch GmbH
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