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Impact sensor

  • US 5,178,013 A
  • Filed: 04/08/1991
  • Issued: 01/12/1993
  • Est. Priority Date: 10/06/1989
  • Status: Expired due to Fees
First Claim
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1. An impact sensor for a vehicle, comprising,a casing attached to the vehicle,a piezoelectric element situated in the casing and adapted to provide a voltage varied in accordance with a pressure applied thereto,a pair of electrodes situated in the casing and sandwiching the piezoelectric element therebetween,a pressure receiving element situated on one of the electrodes, said pressure receiving element having a recess with side faces to converge gradually toward the piezoelectric element, said recess being arranged to extend vertically relative to the vehicle throughout an entire length of the pressure receiving element,an inertial mass disposed on the recess of the pressure receiving element for applying a pressure to the piezoelectric element through the pressure receiving element, said inertial mass having a semispherical end contacting the pressure receiving element,a biasing member situated behind the inertial mass to hold the inertial mass in a center of the recess of the pressure receiving element and to press the inertial mass toward the piezoelectric element at a predetermined pressure so that when the sensor is subject to vertical vibrations, the inertial mass slides vertically in the recess without substantial change of voltage at the piezoelectric element, and when the sensor receives force diagonally from a front direction, a component of the force in a forward direction is received by one of the side faces of the recess and is transmitted to the piezoelectric element, andan adjusting bolt attached to the casing for adjusting pressure of the biasing member relative to the piezoelectric element through the inertial mass.

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