摘要 |
To provide for improved cleaning of an optical combustion sensor, particularly to determine knocking in an internal combustion (IC) engine, a pick-up element made of glass, glass-coated or covered metal or the like, and, for example, hollow inside and filled with a vaporizable and condensable medium to define a heat pipe, has a sensing end portion which is formed with a mushroom-shaped enlarged head (14). The unit may be combined with the functions of a spark plug by extending a conductor therethrough, making the pick-up of electrically conductive glass or ceramic, placing a metal foil or other conductor at the outside, separated from the metallic housing by an insulating sleeve or the like.
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