Patent ID: 8915125

Claim:
A cylinder internal-pressure sensor for an engine, characterized in that the cylinder internal-pressure sensor is formed having a ring shape for detecting an internal pressure of the cylinder by being attached to an outer peripheral surface of a distal end portion of a functional component faced with a combustion chamber of the engine, and provided with a housing unit composed of an outer cylinder portion and an inner cylinder portion having elastic portions having elasticity in an axial direction formed on an intermediate portion in the axial direction; a pressure-receiving ring block portion hermetically fixed between the outer cylinder portion and the inner cylinder portion located on the fronts of the elastic portions and faced with the rear of the elastic portions through the elastic portions and having a front surface as a pressure receiving surface; at least one or more pressure detection elements in contact with one electrode portion provided on a rear surface of this pressure-receiving ring block portion, given the internal pressure by the pressure-receiving ring block portion, and arranged at predetermined positions in a peripheral direction; and a support ring block portion fixed between the outer cylinder portion and the inner cylinder portion, having a front surface as a support surface supporting the pressure detection elements and serving also as the other electrode.