Patent ID: 7032440

Claim:
An engine rotation information detection device that detects rotation information including information on a reference crank angle position of an engine comprising: signal generating device including a rotor in which one of n reluctors (n is an integer equal to or more than three) arranged at regular intervals in a rotational direction of a crankshaft of said engine is missed, a total of n-1 reluctors are arranged in said rotational direction, and a portion from which said one reluctor is missed is a reluctor missing portion, and a pulse signal generator that detects an edge of each of the n-1 reluctors provided on said rotor to generate a pulse, said pulse signal generator detecting an edge of any reluctor of said rotor to generate a pulse when a crank angle position of said engine matches said reference crank angle position; a generator that rotates in synchronization with said crankshaft to output an nxm-cycle AC voltage (m is an integer equal to or more than one); counting means that counts the number of detections of a singular point of a waveform of said AC voltage in each detection section, said detection section being a section between a crank angle position where said pulse signal generator detects the edge of each reluctor to generate a pulse and a crank angle position where said pulse signal generator detects a next reluctor to generate a pulse; and reference crank angle position identification means that uses a difference between a count value counted by said counting means in a detection section including said reluctor missing portion and a count value counted by said counting means in other detection sections to specify the detection section including the reluctor missing portion and identify a pulse generated at said reference crank angle position based on the specified detection section.