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System for monitoring air pressure in a spare tire

  • US 5,513,524 A
  • Filed: 08/08/1994
  • Issued: 05/07/1996
  • Est. Priority Date: 08/08/1994
  • Status: Expired due to Term
First Claim
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1. A system for monitoring air pressure in a land vehicle spare tire comprising:

  • A) a switch unit mounted on a stem of a spare tire and including(1) an electrically conductive casing,(2) means on said casing for opening a valve in the stem and permitting air in the spare tire to escape via the stem,(3) flexible, non-conductive diaphragm means mounted on said casing to be exposed to air pressure from the tire and for closing the casing and capturing the escaping air from the valve within the casing, said diaphragm means moving between a first position when air pressure in the tire is at or above a pre-set level and a second position when air pressure in the tire is below the pre-set level,(4) a first switch contact mounted on said diaphragm to move therewith,(5) electrically conductive spring means mounted on said first switch contact for biasing said first switch contact toward a closed position and biasing said diaphragm means via said first switch contact toward said second position and being electrically connected to said casing, and(6) a second switch contact fixed to said casing and positioned near said first switch contact to be in electrical contact with said first switch contact when said diaphragm means is in said second position, said second switch contact being electrically insulated from said casing and including a pin fixed to an electrically non-conductive sleeve, said sleeve being fixedly mounted on said casing;

    B) a first electrical lead means for connecting said casing to ground;

    C) an alarm means in a vehicle associated with the spare tire for signalling a driver when air pressure in the spare tire is below said pre-set level;

    D) second electrical lead means for connecting said second switch contact to said alarm means;

    E) power means connected to said alarm means so power is applied to said alarm means when said first and second switch contacts are in electrical contact with each other and when a brake light of the vehicle is activated so that power is available for said alarm means when the brakes of the vehicle are being applied whereby said alarm means is connected to said power means but is electrically separated from a complete circuit when said first and second switch contacts are spaced apart and is connected in a complete circuit with said power means when said first and second contact elements are in electrical contact with each other and at least one of the brake lights of said vehicle is operated; and

    F) a quick-connect means for electrically connecting said switch unit to said first and second lead means, said quick-connect means including a housing having an electrically insulating top and an electrically conductive bottom, an opening through said bottom, means on said bottom for electrically connecting said bottom to said casing, a flexible electrical contact element mounted at one end thereof on said top and having a second end located above said opening and being electrically connected to said second electrical lead means, said second end electrically contacting said second switch contact when said quick-connect means is attached to said switch unit.

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