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Electrical anti-theft security system, especially for a motor vehicle

  • US 5,808,543 A
  • Filed: 03/26/1996
  • Issued: 09/15/1998
  • Est. Priority Date: 03/21/1995
  • Status: Expired due to Fees
First Claim
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1. An anti-theft system for a motor vehicle having an engine, an ignition system for the engine, a starter for the engine, and electrical accessories, the vehicle having electrical circuits for supply of power to the ignition system and the said accessories, and a power supply source connected to the said circuits through the anti-theft system, the anti-theft system comprising:

  • an anti-theft switch for controlling starting of the engine and the supply of power to the said circuits;

    a motorised security device comprising a blocking member and an electric drive motor coupled to the blocking member for displacing the latter between a locked position and an unlocked position; and

    a central anti-theft unit connected to the said anti-theft switch and the said motor, the central anti-theft unit being adapted to control operation of the anti-theft system,wherein the said anti-theft switch comprises;

    a key interruptor for detecting simulated introduction of a key into the anti-theft switch; and

    a multiple position control interruptor for connection to said electrical circuits of the vehicle and for controlling power supply to said circuits and to the starter in sequence, the said multiple control interruptor comprising a movable control contact connected to one polarity of the power supply source, and a set of fixed contacts for connection variously to said circuits and to the starter, and so disposed as to be contacted successively by the movable control contact of the multiple position switch as the latter is operated for starting the vehicle, the last one of the said fixed contacts in the said sequence being connected to the starter, and the said control interruptor being adapted so that it cannot be actuated except in the presence of a key,the anti-theft system further including an immobilising device for inhibiting the control interruptor in such a way as to prevent the movable control contact element of the latter from making contact with at least the fixed contact connected to the starter so long as the said system is in a condition other than its unlocked condition, the said immobilising device being such that, in response to a release signal from the central anti-theft unit, it enables the movable contact of the multiple position interruptor to come into contact with the fixed contact for energising the starter,the immobilising device including a power supply unit which is connected directly to the said electrical power supply source and which is connected also to the central anti-theft unit, the system further including detecting means for detecting the unlocked state of the system and for delivering a corresponding signal to the central anti-theft unit,and wherein the central anti-theft unit is adapted to be unable to transmit a release signal to the immobilising device except on receipt of an unlocking signal from the detecting means.

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