US 5,332,301 AGranted

ABS pressure reduction when wheel deceleration exceeds a threshold relative to vehicle deceleration

AssigneeFahrzeumgtechnik Ebern GmbH

InventorsGeorg Roll, Heinz-F. Ohm

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Abstract

In order to avoid cyclic wheel overbraking in an anti-lock control system for automotive vehicles and nevertheless have assurance that each wheel is operated in optimal slippage regions for the longest possible periods of time so that, for instance, the physically maximum vehicle deceleration is obtained with high comfort control, an ABS controller (3) is provided with an additional internal auxiliary circuit (4) which, on basis of measured wheel decelerations and calculated vehicle reference decelerations superimposes, in a manner adapted to the physical circumstances, fine pressure modulations on the normal pressure modulations.

Claims17

Dependent claims

An anti-lock braking control system for automotive vehicles, said system including:

first and second inductive sensors (5, 6) that generate signals indicative of conditions at wheels of a vehicle having said system,
an ABS controller (3) which recognizes conditions of wheel overbraking from said signals and produces corresponding control signals, and
a pressure modulator (1) which is caused by the control signals to adjust the brake pressures on the wheels of said vehicle, with first and second and third pressure-setting phases being passed cyclically through to each wheel so that when overbraking is recognized, in each case a pressure reduction takes place, and when sufficient wheel acceleration occurs again pressure maintenance is effected, and
after the wheel enters a stable slippage region a pressure build-up again takes place until another overbraking again introduces a pressure reduction phase, with steepness of the pressure build-up being increased abruptly by activation of a search ramp if the pressure build-up does not lead to overbraking of the wheel, within a predetermined period of time TP on;
the ABS controller (3) being provided with an additional internal auxiliary circuit (4) which, on the basis of measured wheel decelerations and calculated vehicle reference decelerations AREF, superimposes adaptively in relation to physical circumstances, a fine pressure modulation on the normal pressure modulations;
for each controlled wheel, the auxiliary circuit (4) produces a pressure-maintenance signal if wheel deceleration is greater than the vehicle reference deceleration increased by a threshold DeltaA1, and produces a pressure reduction signal if wheel deceleration is greater than the vehicle reference deceleration increased by a threshold DeltaA2 (DeltaA2 >DeltaA1), whereby:
the ABS controller maintains the brake pressure of the wheel in question or even reduces it when wheel 40 speed is still in a stable slippage region;
the auxiliary circuit (4) increases the time TS for activating of the search ramp in the absence of a wheel-locking tendency whenever a pressure-release signal has been given during the pressure build-up;
and
as a function of the vehicle reference deceleration AREF reached the auxiliary circuit (4), currently calculates a variable slope DeltaPSearch for the search ramp, with the variable slope decreasing as AREF increases.

7 more elements

Dependencies are inferred from the claim text.

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Abstract

An anti-lock braking control system for automotive vehicles, said system including:

first and second inductive sensors (5, 6) that generate signals indicative of conditions at wheels of a vehicle having said system,
an ABS controller (3) which recognizes conditions of wheel overbraking from said signals and produces corresponding control signals, and
a pressure modulator (1) which is caused by the control signals to adjust the brake pressures on the wheels of said vehicle, with first and second and third pressure-setting phases being passed cyclically through to each wheel so that when overbraking is recognized, in each case a pressure reduction takes place, and when sufficient wheel acceleration occurs again pressure maintenance is effected, and
after the wheel enters a stable slippage region a pressure build-up again takes place until another overbraking again introduces a pressure reduction phase, with steepness of the pressure build-up being increased abruptly by activation of a search ramp if the pressure build-up does not lead to overbraking of the wheel, within a predetermined period of time TP on;
the ABS controller (3) being provided with an additional internal auxiliary circuit (4) which, on the basis of measured wheel decelerations and calculated vehicle reference decelerations AREF, superimposes adaptively in relation to physical circumstances, a fine pressure modulation on the normal pressure modulations;
for each controlled wheel, the auxiliary circuit (4) produces a pressure-maintenance signal if wheel deceleration is greater than the vehicle reference deceleration increased by a threshold DeltaA1, and produces a pressure reduction signal if wheel deceleration is greater than the vehicle reference deceleration increased by a threshold DeltaA2 (DeltaA2 >DeltaA1), whereby:
the ABS controller maintains the brake pressure of the wheel in question or even reduces it when wheel 40 speed is still in a stable slippage region;
the auxiliary circuit (4) increases the time TS for activating of the search ramp in the absence of a wheel-locking tendency whenever a pressure-release signal has been given during the pressure build-up;
and
as a function of the vehicle reference deceleration AREF reached the auxiliary circuit (4), currently calculates a variable slope DeltaPSearch for the search ramp, with the variable slope decreasing as AREF increases.

7 more elements