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Fail-safe system for an anti-skid control system for an automotive brake system

  • US 4,980,832 A
  • Filed: 09/02/1988
  • Issued: 12/25/1990
  • Est. Priority Date: 09/04/1987
  • Status: Expired due to Term
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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