Patent ID: 7284538

Claim:
A rotation angle sensing device that reads in an output of a crank angle sensor for sensing multiple sensed portions rotating in synchronization with rotation of a crankshaft of an internal combustion engine to sense a rotation angle of the crankshaft, the rotation angle sensing device comprising: a fuel cutting control device that performs fuel cutting control for stopping fuel injection generating torque of the crankshaft; a calculation device that divides entire sections defined by one or more rotations of the crankshaft into multiple sections by using the sensed portions and that calculates time necessary for rotation of each one of the multiple sections based on the output of the crank angle sensor obtained during the fuel cutting control; an averaging device that calculates an average value of multiple calculation values of the calculation device for each section; and an error sensing device that senses an angle error of an arbitrary section out of the multiple sections based on comparison between the average value of the arbitrary section and the average value of another section or comparison between the average value of the arbitrary section and an average value of the average values of two or more sections out of the multiple sections.