Patent ID: 7624620

Claim:
A combustion pressure sensor for an engine having an engine head formed with a combustion chamber and a through-bore communicating therewith, the combustion pressure sensor comprising: a housing adapted to be mounted to the through-bore of the engine head in a gastight structure and internally having a hollow portion; a transfer member slidably disposed in the hollow portion of the housing and having a pressure-receiving portion exposed to the combustion chamber for receiving a combustion pressure to allow the combustion pressure, received with the pressure- receiving portion, to transfer; a pressure sensor mounted between the housing and the transfer member and exerted with a preliminary pressure for detecting a load resulting from the combustion pressure received with the transfer member; and a seal member fixedly disposed between the housing and the transfer member in a gastight relationship to block the combustion pressure prevailing in the combustion chamber from intruding into an inside of the housing; wherein the seal member includes a flexible portion operative to absorb a fluctuation in load actuating on the pressure sensor due to a relative movement of the transfer member caused by a compressive contraction of the housing mounted to the engine head, wherein the seal member includes a facing portion facing an outer periphery of the transfer member and extending parallel to an axis thereof, and an orthogonal planar portion extending perpendicular to the facing portion; and wherein the flexible portion is formed on the facing portion with a rigidity lower than that of the orthogonal planar portion.