Pressure sensor equipped with pressure sensing diaphragm

A pressure sensor is provided which may be employed in measuring the combustion pressure in an internal combustion engine. The pressure sensor is equipped with a pressure sensing diaphragm assembly which includes a first diaphragm, a second diaphragm, and liquid or gel. The first diaphragm is flexible when exposed to pressure to be measured and joined to the second diaphragm to define a closed chamber filled with the liquid or gel to transmit the pressure to the second diaphragm. A pressure transmitting member is disposed in abutment with the second diaphragm to transmit the pressure, as transmitted from the first diaphragm, to a pressure sensing device. The inclusion of the liquid or gel in the closed chamber between the first and second diaphragms results in an increase in heat capacity of the diaphragm assembly to decrease the thermal distortion thereof without sacrificing the sensitivity of the pressure sensor.