EINRICHTUNG ZUR MESSUNG DES DREHWINKELS EINER MASCHINENWELLE RELATIV ZU EINER BEZUGSWINKELSTELLUNG

An apparatus is disclosed, for measuring the angular position of a crank shaft of an i.c. engine at the occurrence of a rise in pressure in the fuel injection line to the engine, relative to a reference position of the shaft. The apparatus comprises a first sensor responsive to the reference position of the shaft (signal II) and a second sensor which, on the occurrence of the pressure rise, produces an output pulse and which produces a number of interference pulses in the periods between production of the output pulses (signal I). A comparator (4) having a threshold value B which is capable of being exceeded both by the required pulses and the interference pulses, and a recognition circuit (3, 6) which is adapted to recognise output pulses produced on the occurrence of the event, are arranged to control an evaluation circuit such as a counter (10). The evaluation circuit ascertains, e.g. by counting angular increment marker pulses (signal III), the angle through which the shaft rotates between the time when the threshold of the comparator (4) was last exceeded prior to triggering of the recognition circuit by the required event, and the time when the shaft reaches the reference position.