Patent ID: 7921698
Filing Date: 2011-04-12
Classification: G01M

Abstract:
1. A method of detecting a crank angle of an engine, said method comprising the steps of: (a) coupling a crank pulse rotor to a crankshaft of the engine, said crank pulse rotor comprising a non-toothed portion formed by removing at least one of a plurality teeth consecutively formed at predetermined intervals on an outer circumference of the crank pulse rotor; wherein the teeth consecutively formed on the crank pulse rotor are arranged in a range including a position corresponding to a top dead center position of a piston of the engine; (b) measuring successive time intervals between adjacent teeth of the pulse rotor during rotation of the crankshaft, wherein said successive time intervals include a last time interval and a second-to last time interval which is immediately preceding said last time interval; (c) calculating crank pulse interval ratios by dividing said currently measured time interval by said immediately preceding time interval; (d) comparing a current crank pulse ratio with an immediately preceding crank pulse ratio; (e) retaining a larger ratio value selected from said current pulse ratio and said immediately preceding crank pulse ratio; (f) repeating the method steps (b) through (e) for a cycle of the engine; and (g) determining presence of the non-toothed portion when the ratio of the crank pulse intervals calculated is the maximum ratio within said cycle of the engine.