Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1998-10-26
2001-01-30
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S070000, C701S084000, C701S090000, C303S139000, C303S113200, C180S197000, C290S04000F, C477S186000, C477S187000
Reexamination Certificate
active
06182002
ABSTRACT:
This invention relates to vehicle traction control systems that reduce torque at the vehicle wheels in response to a detected wheel spin condition.
BACKGROUND OF THE INVENTION
Automotive traction control systems have been developed as a stability enhancement feature, and operate to reduce wheel torque in response to a detected wheel spin condition. A number of control variables have been utilized to carry out the torque reduction, including engine fuel reduction, engine spark retard, engine throttle control, and brake controls. In general, detection of the wheel spin condition is achieved by precisely monitoring the speeds of the driven wheels and comparing them with the speeds of un-driven wheels or a vehicle reference speed.
The incremental cost of providing a traction control function is minimized in vehicles having an anti-lock brake system since the required wheel speed and reference speed information is available at little or no additional cost. However, the incremental cost of traction control is much higher in vehicles where anti-lock brake system inputs and variables are not available. Accordingly, it is desired to provide a traction control system that does not require high resolution wheel speed sensors, and yet can be made available at a small incremental cost.
SUMMARY OF THE INVENTION
The present invention is directed to an improved traction control system in which a wheel spin condition is detected based on measured vehicle acceleration instead of measured wheel speeds. According to the invention, an electronic controller detects a wheel spin condition by computing the acceleration of the vehicle drive shaft and comparing the computed acceleration to an acceleration threshold stored as function of vehicle speed and wheel torque. If the computed acceleration exceeds the threshold for more than a predetermined time, the engine torque is reduced in relation to the amount by which the computed acceleration exceeds the threshold. When the computed acceleration falls below the threshold, the torque reduction is gradually removed.
The wheel torque, vehicle speed and drive shaft acceleration are easily determined and filtered, and the incremental cost of the traction control function is primarily related to the memory requirements to accommodate the acceleration threshold look-up table. In the illustrated embodiment, the control is mechanized in a vehicle having electronic throttle control, and the desired torque reduction is achieved with throttle area control, spark timing control and fuel cutoff control.
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Bauerle Paul Alan
Colby Stephen E.
DeVries Christopher
General Motors Corporation
Louis-Jacques Jacques H.
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