Patent ID: 8818685

Claim:
A rotation detecting device for determining normal rotation and reverse rotation of a rotating shaft of a vehicle, comprising: an output unit for generating a rotation signal output in response to rotation of the rotating shaft of a vehicle, the rotation signal being different between the normal rotation and the reverse rotation of the rotating shaft; a first determination unit for determining whether the rotating shaft is rotated in one of the normal direction and the reverse direction based on an operating condition of the vehicle; a setting unit for setting a threshold value which determines whether the rotation signal indicates the normal rotation or the reverse rotation based on a determined rotating direction and the rotation signal; a second determination unit for determining the normal rotation and reverse rotation of the rotating shaft based on the rotation signal and the threshold value; wherein the rotating shaft is an output shaft of an internal combustion engine; wherein the first determination unit determines whether or not the output shaft is rotating normally based on at least one of engine rotating speed, a cylinder in which a piston is in a predetermined position, an engine load, a starting operating state, intake pressure, and battery voltage; and wherein the first determination unit determines that the output shaft is rotating normally when an updating order of the cylinder of which piston position is determined to be in the predetermined position is normal.