Apparatus for identification of cylinders in an internal combustion engine

A cylinder identifying apparatus for an internal combustion engine, comprising:

• cylinder discrimination signal generation means for generating a cylinder discrimination signal in correspondence with each of cylinders of the internal combustion engine according to the rotation of a camshaft of the internal combustion engine;
• crank angle position signal generation means including a member rotating through two revolutions when the camshaft rotates through one revolution, said crank angle position signal generation means for generating a crank angle position signal including pulse dropout portions corresponding to each of the cylinders of the internal combustion engine in accordance with the rotation angle of a crankshaft of the internal combustion engine;
• and
• a control unit for detecting the crank angle position signal to obtain the number of detections of the crank angle position signal;
• detecting a reference crank position on the basis of one of the pulse dropout portions of the crank angle position signal;
• detecting the cylinder discrimination signal to obtain the number of detections of the cylinder discrimination signal;
• obtaining the number of detections of the crank angle position signal when the cylinder discrimination signal is detected;
• obtaining the number of pulse dropouts on the basis of one of the pulse dropout portions of the crank angle position signal;
• obtaining the number of detections of the reference crank position;
• setting a first cylinder discrimination period with reference to the reference crank position when said control unit determines that the present reference crank position is the result of first-time detection after startup on the basis of the number of detections of the reference crank position;
• setting a second cylinder discrimination period different from the first cylinder discrimination period with reference to the reference crank position when said control unit determines that the present reference crank position is the result of second-time or some other subsequent detection after the startup;
• obtaining the number of detections of the cylinder discrimination signal in the first or second cylinder discrimination period on the basis of the number of detections of the cylinder discrimination signal and the number of detections of the crank angle position signal at the time of detection of the cylinder discrimination signal;
• and identifying one of the cylinders on the basis of the number of pulse dropouts and the number of detections of the cylinder discrimination signal in the first or second cylinder discrimination period.