Abstract: A conductor (5) which varies its resistance value under the influence of pressure is introduced into the combustion chamber of the engine. In one embodiment the conductor is a wire (5), a coil, a meander pattern or the like; preferably, one part (5a) of the wire arrangement is shielded from the pressure. The shielded (5a) and the unshielded (5b) parts of the wire arrangement then form the branches of a bridge circuit. The sensor is preferably disposed in the breathing room (11) of a spark plug or for a Diesel engine, combined with an electric conductor (21, 44) serving to provide pre-glowing in a glow plug. Combustion pressures are thus sensed for controlling and/or regulating injection systems and/or ignition systems without requiring additional bores.

Abstract: To sense pressure within the combustion chamber of an internal combustion engine (ICE), a plug element which already extends into the combustion chamber of the ICE, such as a sparkplug, or a glow plug, has a layer-like resistor applied to a ceramic insulator extending into the combustion chamber, for example, directly on the central insulator of a sparkplug or on the side of a ceramic glow plug bushing or plug element. If applied to a sparkplug then, preferably, the heater is shielded by metallic layers, separated from the metallic shielding layers by insulating layers, of which the top metallic layer preferably is platinum or a platinum-type metal to catalyze combustion of residues which, otherwise, might collect on the top layer and interfere with proper sensor operation. The layer-like sensor and conductive tracks may be of thick film construction; stamp-on printing with flexible printing stamps is suitable to apply the layer-like resistors.