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Tire pressure warning system

  • US 4,574,267 A
  • Filed: 06/14/1985
  • Issued: 03/04/1986
  • Est. Priority Date: 05/06/1982
  • Status: Expired due to Term
First Claim
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1. Apparatus for detecting changes in inflation pressure of a tire on a vehicle, said apparatus comprising:

  • means for generating an electric signal indicative of vertical accelerations experienced by said tire, said accelerations exhibiting a resonant frequency dependent upon inflation pressure of said tire;

    means for determining a first value of the resonant frequency experienced by said tire at a first time and for determining a second value of the resonant frequency experienced by said tire at a second time, both determined from said generated electric signal indicative of the vertical accelerations experienced by said tire;

    means for storing said determined first value of the resonant frequency experienced by said tire;

    comparing means for comparing said determined second value of the resonant frequency experienced by said tire with said stored determined first value of the resonant frequency experienced by said tire and for generating a signal indicative of a difference therebetween; and

    alarm means responsive to said comparing means for providing an alarm to a driver when said signal generated by said comparing means indicates there is a difference between said stored determined first value of the resonant frequency and said determined second value of the resonant frequency greater than a predetermined amount.

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