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Fiber optic diaphragm sensors for engine knock and misfire detection

  • US 5,390,546 A
  • Filed: 07/01/1993
  • Issued: 02/21/1995
  • Est. Priority Date: 07/01/1993
  • Status: Expired due to Term
First Claim
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1. In a fiber optic diaphragm sensor comprising a body having a cavity approximately 3 mm across therein, a diaphragm attached to the body and partially enclosing the cavity, the diaphragm being moveable in response to changes in fluid pressure exerted upon the diaphragm, andan optical fiber inserted in the body with the tip end of the optical fiber disposed to inject a light beam into the cavity and receive a reflected light beam,the improvement comprising moveable reflective means interposed in the cavity to intercept and reflect back the injected light beam, mechanical means interconnecting the reflective means to the diaphragm whereby movement of the diaphragm in response to changes in fluid pressure activates responsive movement of the reflective means and modulation of the light beam reflected back to the tip end of the optical fiber, said mechanical means interposed between the diaphragm and reflective means to provide a substantial temperature differential between the diaphragm and reflective means when the diaphragm is hot.

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