A torque limiting arrangement in an i.c. engine.

摘要

In engine-powered machines (motor cutting saw, motor chain saw) with a centrifugal clutch a wearing on the clutch and belt takes place by a high load at an r.p.m. around or above the skidding r.p.m. of the centrifugal clutch. A step for reducing the said wearing can - according to the invention - be taken by limiting the driving torque of the engine in the above-said r.p.m. interval. The invention means that the cutting machine/motor saw is provided with electronic equipment counting r.p.m. and then controlling the ignition system so that the torque of the engine is lowered in a predetermined interval. In a cutting machine ignition is allowed in. for example, every third revolution within the interval 3000 - 6000 r.p.m. The working mode can also be widened so that the time difference between several revolutions is detected. It is then possible to indicate when the cutting machine/motor saw is in acceleration and thus refrain from reduction of the torque of the engine in order to make the machine rapidly return to a proper r.p.m. after a reduction thereof.