Engine, cylinder identification (CID) transducer

Claim 1

In an engine diagnostic system of the type which monitors the operation of a combustion engine and provides signal information representative of the engine operating performance characteristics, the signal information including a series of sensed, periodic cylinder identification (CID) signal pulses representative of the stroke of an engine cylinder piston through a reference piston position as provided by a sensor in response to the cyclic displacement of an engine component member having a cyclic function directly related to the piston stroke of the cylinder, each CID pulse having a pulse width in dependence on the spatial distance between the sensor and the member during its cyclic displacement and on the period of the member displacement cycle which is related to the instantaneous revolutions per minute (RPM) of the engine, the signal information further including a series of tooth signal pulses, each representative of a corresponding one of a plurality of gear teeth disposed on the ring gear assembly of the engine flywheel housing, the tooth signal pulse frequency being dependent on the engine RPM; an engine cylinder identification (CID) transducer for providing a CID signal manifestation of the stroke of an engine cylinder piston through a reference piston position which is not dependent on the spatial distance between the sensor and the engine component member or on the engine RPM, comprising: detection means, responsive to the series of sensed CID signals, for providing a series of CID gate signals, one for each of the sensed CID signals, each having a time duration in dependence on the pulse width of a corresponding sensed CID signal, the time duration of each representing a CID interval; counting means, responsive to said CID gate signals and to the series of tooth signal pulses, for providing an instantaneous tooth count signal having a magnitude representative of the instant number of tooth signal pulses present within a given one of said CID intervals, and for providing a total tooth count having a magnitude representative of the total number of tooth signal pulses present within each of said CID intervals; and signal generator means, connected for response to said counting means, for providing a signal manifestation whenever the instantaneous tooth count signal magnitude from a present CID interval exceeds one-half of the total tooth count signal magnitude from an immediately preceding CID interval, said signal manifestation being representative of the stroke of the cylinder piston through the reference piston position.