Patent ID: 6301957
Filing Date: 2001-10-16
Classification: G01L,G01M

Abstract:
An on-vehicle fiber-optic cylinder pressure sensor comprising:an optical fiber having a pressure-sensitive characteristic capable of converting a change in pressure within a combustion chamber of an internal combustion engine into a change in a light quantity passing therethrough;light emitting means for providing said light quantity to said optical fiber;photosensing means for sensing said light quantity passed-through said optical fiber, said light quantity having been changed while passing through said optical fiber;means for converting said changed light quantity into a detected electric signal;means for setting a reference electric signal corresponding to a reference pressure; andmeans for detecting a variation of said pressure within the combustion chamber of the internal combustion engine from said reference pressure by a correlation between said detected electric signal and said reference electric signal;wherein a corresponding reference electric signal which is determined based on said detected electric signal is monitored and said light quantity emitted from said light emitting means is controlled such that said corresponding reference electric signal and said reference electric signal are equal to each other.