Abstract: To provide for simultaneous transmission of pressure signals and light signals from the combustion chamber (CC) of an internal combustion engine or, selectively, either one or the other of the pressure or light signals, independently, a spark plug-type housing (1, 2) has a glass plug (3) fitted therein, the end face of which at the side remote from the combustion chamber engaging a piezo-ceramic ring (4). The inner opening of the ring (4) transmits light from the glass plug or rod 3 to a light guide fiber cable (7) which, concentrically and insulated from each other, has a metal woven sleeve (10) placed thereabout, and an outer metallic jacket (12), the woven sleeve (10) being connected to a flanged ring (6, 6a) engaging one end face of the piezo-ceramic ring (4), the other end face being connected to the outer metallic sleeve (12) to provide a coaxial electrical signal output cable, with the inner portion thereof surrounding and forming a jacket for the light guide fiber cable (7).

Abstract: To determine proper operation of a combustion sensor, and to normalize the output signals derived from a pick-up having a window exposed to the combustion chamber (10) by compensating for soiling, contamination, and loss of transmissivity of the window due to combustion residue, soot, or the like, a reference light source is provided introducing reference light of a predetermined level to the pick-up, for example when no light is generated due to combustoin events. In an internal combustion (IC) engine, the reference light can be energized during stopped condition of the engine, or during portions of the stroke of the engine when no combustion event takes place.

Abstract: A method is proposed for regulating the combustion of operating mixtures in the combustion chambers of internal combustion engines. The course of the light intensity of the light resulting from combustion in the combustion chamber is detected and evaluated over the course of combustion; reference control variables derived therefrom are formed for use by subsequently disposed closed-loop control devices of the engine.