Engine ignition timing control apparatus

Abstract

An apparatus for controlling the timing of ignition of an internal combustion engine. The apparatus includes a cylinder pressure sensor sensitive to combustion pressure in a cylinder for providing a signal indicative of a sensed cylinder combustion pressure, and a control circuit responsive to the cylinder combustion pressure indicative signal for controlling the engine ignition timing. The control circuit measures a crankshaft angle at which the cylinder combustion pressure is at maximum. The control circuit retards the ignition timing when the measured crankshaft angle is less than a first value and advances the ignition timing when the measured crankshaft angle is greater than a second value greater than the first value. The control circuit retails the ignition timing to interrupt the feedback control of the ignition timing when the measured crankshaft angle is in a range defined by the first and second values. This is effective to eliminate a tendency toward unstable engine operation resulting from the conventional manner in which the ignition timing is re-adjusted at more frequent intervals than is required.

Dependencies are inferred from the claim text.