Glow ignition detection in an internal combustion engine

摘要

Disclosed is a method for monitoring glow ignition in a spark-ignition internal combustion engine. The method comprises: monitoring a crankshaft speed of the engine over a detection window corresponding to a crankshaft deceleration phase during a compression stroke in a given engine cylinder; determining a glow indicator based on a crankshaft speed deceleration gradient between two points defined by their respective crankshaft speed and crank angle, wherein the first point (Pinit) is defined by a predetermined crankshaft angle and corresponding speed during said deceleration, and the second point (Pmin) is a point of lowest speed reached during said deceleration. The method then compares the glow indicator to a predetermined threshold in order to detect the presence or absence of glow ignition. The method uses the fact that early ignition causes the crankshaft to slow before the point at which spark-ignition should occur. The first point, which is defined by a predetermined crankshaft angle and a corresponding speed, may be selected so that it is a stable fixed point. The second point will vary noticeably between normal ignition and early ignition, since the lowest speed will be reached earlier when there is glow ignition than is the case with normal ignition, and this will noticeably change the gradient between the two points allowing detection of glow ignition. Glow ignition may be caused by hot spots in the cylinder or incandescent particles in the air-fuel mix in the cylinder.