Patent ID: 7621176

Claim:
A method for absolute crankshaft angle determination of a revolving crankshaft of a two-stroke engine of a hand-held power tool, wherein the two-stroke engine has a single cylinder with a combustion chamber that is delimited by a piston and is provided with a spark plug, wherein the two-stoke engine has a crankcase with a crankshaft rotatably supported in the crankcase and driven by the piston, wherein the crankcase is connected by at least one transfer passage to the combustion chamber, wherein the at least one transfer passage has a transfer port that is controlled by the piston, and wherein the two-stroke engine comprises an ignition control unit triggering a spark at the spark plug when an adjusted crankshaft angle is reached, and wherein the two-stroke engine comprises an energy supply unit driven by the crankshaft for providing electric energy for ignition, the method comprising the steps of: providing a signal generator as an energy supply unit; generating an alternating voltage signal with the signal generator which voltage signal is caused by a crankshaft revolution, wherein the voltage signal of the signal generator has sequential zero crossings; detecting an operating pressure signal of the two-stroke engine by a pressure sensor; correlating a significant feature of the output signal of the pressure sensor to a known angle position of the crankshaft, wherein the significant feature occurs once for each revolution of the crankshaft; linking an output signal of the pressure sensor and an output signal of the signal generator with one another for determining an absolute crankshaft angle such that; when the significant feature in the output signal of the pressure sensor occurs, a crankshaft angle of the known angle position is assigned as the absolute crankshaft angle to the voltage signal, wherein a periodic duration of the voltage signal matches an n-th part of a crankshaft revolution wherein n is an integer greater than 2; wherein, after assigning the absolute crankshaft angle to the voltage signal, a subsequent zero crossing of the voltage signal is synchronized with the crankshaft angle; wherein, after synchronization, the absolute crankshaft angle of the crankshaft at any point in time of a crankshaft revolution can be determined based on the zero crossings of the voltage signal.