Fail-safe system for an anti-skid control system for an automotive brake system
First Claim
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1. A fail-safe system for an anti-skid brake control system, said fail-safe system comprising:
- a hydraulic brake circuit having means for building up braking fluid pressure according to an operational magnitude of a manually operable braking and braking force generating means, associated with a vehicular wheel, for generating braking force to decelerate said vehicular wheel;
a pressure adjusting means, disposed within said hydraulic brake circuit, for adjusting pressure of a working fluid to be delivered to said braking force generating means, said pressure said adjusting means being operable at least in a first mode for increasing braking pressure in said braking force generating means and in a second mode for decreasing said braking pressure;
a sensor means for monitoring a rotation speed of said vehicular wheel to produce a sensor signal representative of said rotation speed of said vehicular wheel;
controller means for processing said rotation of said vehicular wheel in order to derive a wheel slippage and for generating a control signal for said pressure adjusting means for switching an operational mode of said pressure adjusting means between said first and second modes as as to maintain wheel slippage close to a predetermined value;
pulse generator means, associated with said controller means, for periodically generating a pulse signal having a substantially short pulse width, said pulse signal being combined with said control signal for periodically modifying said control signal to produce a periodically occurring control signal to periodically order said first mode;
detector means for detecting an interval of said periodically occurring control signal ordering said first mode longer than a predetermined period to produce a fail detection signal; and
fail-safe means, responsive to said fail detection signal, for preforming fail-safe operation to fix said pressure adjusting means at said first mode.
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Abstract
An anti-skid brake control system is designed to periodically generate short commands ordering an APPLICATION mode operation to increase braking pressure while the system operates in a RELEASE mode. An anti-skid control signal is then monitored to make a judgement that failure occurs in the anti-skid brake control system when the control signal is not periodically switched from RELEASE mode to APPLICATION mode.
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Citations
14 Claims
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1. A fail-safe system for an anti-skid brake control system, said fail-safe system comprising:
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a hydraulic brake circuit having means for building up braking fluid pressure according to an operational magnitude of a manually operable braking and braking force generating means, associated with a vehicular wheel, for generating braking force to decelerate said vehicular wheel; a pressure adjusting means, disposed within said hydraulic brake circuit, for adjusting pressure of a working fluid to be delivered to said braking force generating means, said pressure said adjusting means being operable at least in a first mode for increasing braking pressure in said braking force generating means and in a second mode for decreasing said braking pressure; a sensor means for monitoring a rotation speed of said vehicular wheel to produce a sensor signal representative of said rotation speed of said vehicular wheel; controller means for processing said rotation of said vehicular wheel in order to derive a wheel slippage and for generating a control signal for said pressure adjusting means for switching an operational mode of said pressure adjusting means between said first and second modes as as to maintain wheel slippage close to a predetermined value; pulse generator means, associated with said controller means, for periodically generating a pulse signal having a substantially short pulse width, said pulse signal being combined with said control signal for periodically modifying said control signal to produce a periodically occurring control signal to periodically order said first mode; detector means for detecting an interval of said periodically occurring control signal ordering said first mode longer than a predetermined period to produce a fail detection signal; and fail-safe means, responsive to said fail detection signal, for preforming fail-safe operation to fix said pressure adjusting means at said first mode. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fail-safe system for an anti-skid brake control system, said fail-safe system comprising:
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a hydraulic brake circuit having means for building up braking fluid pressure according to an operational magnitude of a manually operable braking member, and braking force generating means, associated with a vehicular wheel, for generating braking force to decelerate said vehicular wheel; a pressure adjusting means, disposed within said hydraulic brake circuit, for adjusting pressure of a working fluid to be delivered to said braking force generating means, said pressure adjusting means being operable in a first mode for increasing braking pressure in said braking force generating means and in a second mode for decreasing said braking pressure and in a third mode for holding said braking pressure constant; a sensor means for monitoring a rotation speed of said vehicular wheel to produce a sensor signal representative of said rotation speed of said vehicular wheel; controller means for processing said rotation speed of said vehicular wheel in order to derive a wheel slippage and for generating a control signal for said pressure adjusting means for switching an operational mode of said pressure adjusting means between said first and second modes so as to maintain said wheel slippage close to a predetermined value, said control signal being variable among a first level ordering said first mode, a second level ordering said second mode and a third level ordering said third mode; pulse generator means, associated with said controller means, for periodically generating a pulse signal having a substantially short pulse width, said pulse signal being combined with said control signal for periodically modifying a signal level of said control signal from a signal level other than said first level to said first level; detector means for detecting an interval of said periodically occurring first level control signal longer than a predetermined period to produce a fail detection signal; and fail-safe means, responsive to said fail detection signal, for performing fail-safe operation to fix said control signal at said first level. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification