Method and system for detecting wheel slippage
First Claim
1. A system for detecting wheel slippage comprising:
- a first sensor for monitoring wheel rotation and producing a first sensor signal indicative of the wheel speed;
a second sensor for monitoring a parameter reflecting road surface friction and producing a second sensor signal indicative thereof;
a reference signal generator for sampling said first sensor signal having at a given timing and generating a reference signal having a value reflecting a projected vehicle speed based on the sampled first sensor signal value; and
an arithmetic means for modifying said reference signal value based on said second sensor signal value and comparing said first sensor signal value with the modified reference signal value so as to detect occurrences of wheel slippage.
1 Assignment
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Accused Products
Abstract
A method and a system derive a value representative of an actual vehicle speed in strict correspondence to actual vehicle speed. The value can be utilized to detect wheel slippage and allows precise traction control, anti-skid brake control and so forth. The method for deriving wheel slippage, according to the present invention, includes a step of deriving a projected vehicle speed, the rate of change of which varies with road surface friction. Wheel slippage is derived from on the projected vehicle speed and instantaneous wheel speed. In practice, the method includes a step for detecting the force exerted on a vehicular wheel, which force includes a resistance variable depending upon the road surface friction μ. Based on the detected force, the projected vehicle speed variation pattern is derived so as to derive an instantaneous projected vehicle speed.
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Citations
14 Claims
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1. A system for detecting wheel slippage comprising:
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a first sensor for monitoring wheel rotation and producing a first sensor signal indicative of the wheel speed; a second sensor for monitoring a parameter reflecting road surface friction and producing a second sensor signal indicative thereof; a reference signal generator for sampling said first sensor signal having at a given timing and generating a reference signal having a value reflecting a projected vehicle speed based on the sampled first sensor signal value; and an arithmetic means for modifying said reference signal value based on said second sensor signal value and comparing said first sensor signal value with the modified reference signal value so as to detect occurrences of wheel slippage. - View Dependent Claims (2, 3, 4)
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5. A method for detecting wheel slippage comprising the steps of:
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monitoring wheel rotation and producing a first signal indicative of the wheel speed; monitoring a parameter reflecting road surface friction and producing a second signal indicative thereof; sampling said first signal at a given timing for generating a reference signal having a value reflecting a projected vehicle speed based on the sampled first signal value; modifying said reference signal value based on said second signal value; and comparing said first signal value with the modified reference signal value so as to detect occurrence of wheel slippage. - View Dependent Claims (6, 7, 8)
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9. A traction control system for an automotive vehicle having a wheel receiving driving torque from an automotive engine, comprising:
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a first sensor for monitoring wheel rotation and producing a first sensor signal indicative of the wheel speed; a second sensor for monitoring a parameter reflecting road surface friction and producing a second sensor signal indicative thereof; a reference signal generator for sampling said first sensor signal at a given timing and generating a reference signal having a value reflecting a projected vehicle speed based on the sampled first sensor signal value and a predetermined vehicle speed variation representative coefficient; controller means for modifying said reference signal value by adjusting said vehicle speed variation representative coefficient based on said second sensor signal value and comparing said first sensor signal value with the modified reference signal value so as to detect occurrences of wheel slippage and in such cases producing a control signal ordering reduction of driving torque exerted onto said wheel for recovering traction; and means for adjusting the driving torque exerted on the wheel, said driving torque adjusting means being responsive to said control signal to reduce the driving torque exerted on said wheel. - View Dependent Claims (10, 11, 12)
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13. A traction control system for an automotive vehicle having a wheel receiving driving torque from an automotive engine, comprising:
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a first sensor for monitoring wheel rotation and producing a first sensor signal indicative of the wheel speed; a second sensor for monitoring a parameter reflecting road surface friction and producing a second sensor signal indicative thereof; a reference signal generator for generating a reference signal having a value reflecting a projected vehicle speed based on the first sensor signal value; controller means for modifying said reference signal value based on said second sensor signal value and comparing said first sensor signal value with the modified sensor signal value so as to detect occurrences of wheel slippage and in such cases producing a control signal ordering reduction of driving torque exerted on said wheel for recovering traction; and means for adjusting the driving torque exerted on the wheel, said driving torque adjusting means being responsive to said control signal to reduce the driving torque exerted on said wheel, said means for adjusting including a hydraulic clutch with adjustable engaging pressure for adjusting driving torque and a valve means operable in response to said control signal for adjusting said engaging pressure so as to adjust the driving torque exerted on said wheel.
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14. A traction control system for an automotive vehicle having a wheel receiving driving torque from an automotive engine, comprising:
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a first sensor for monitoring wheel rotation and producing a first sensor signal indicative of the wheel speed; a second sensor for monitoring a parameter reflecting road surface friction and producing a second sensor signal indicative thereof; a reference signal generator for generating a reference signal having a value reflecting a projected vehicle speed based on the first sensor signal value; controller means for modifying said reference signal value based on said second sensor signal value and comparing said first sensor signal value so as to detect occurrence of wheel slippage and in such cases producing a control signal ordering reduction of driving torque exerted on said wheel for recovering traction; and means for adjusting the driving torque exerted on the wheel, said driving torque adjusting means being responsive to said control signal to reduce the driving torque exerted on said wheel, said means for adjusting including an engine speed adjusting means which is responsive to said control signal for reducing engine speed so as to reduce the driving torque exerted on the wheel.
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Specification