Patent ID: 7974767

Claim:
A method for detecting an operating parameter of a power tool comprising an internal combustion engine, wherein the internal combustion engine comprises at least one cylinder and a crankcase, wherein a combustion chamber is defined in the cylinder and is delimited by a piston, wherein the piston drives in rotation a crankshaft supported rotatably in the crankcase, wherein an intake is provided that supplies combustion air to the combustion chamber and an exhaust is provided for removing combustion gases from the combustion chamber, wherein an alternating current generator is provided that is driven in rotation by the crankshaft and emits for one crankshaft revolution sequential alternating voltage signals, the method comprising the steps of: selecting a period duration of a voltage signal so as to correspond to the n-th portion of a crankshaft revolution with n being a number greater than 2, wherein the n-th portion of the crankshaft revolution forms a crankshaft angle interval; detecting for each crankshaft angle interval at least one information, wherein the at least one information of the crankshaft angle interval is plotted against the crankshaft angle to represent a course of the at least one information across the crankshaft angle; scanning the course of the at least one information with regard to a characteristic feature; correlating the characteristic feature with an operating parameter of the power tool; wherein the at least one information is the interval engine speed and represents an engine speed course across at least one complete revolution of the crankshaft, wherein the engine speed course is scanned with regard to the characteristic feature.