Operator carried power tool having a four-cycle engine

摘要

A handheld powered tool (20) is provided which is intended to be carried by an operator during use. The power tool (20) has a frame (22), including a handle (24, 26) to be grasped by the operator, an implement (32) affixed to the frame (22) having a rotary input member (64) and a small four-cycle aluminium internal combustion engine (30) attached to the frame for driving the implement. A crankshaft (36) is journaled to the engine block for rotation about a crankshaft axis. A piston (38) reciprocates within the bore (34) and is connected to the crankshaft by a connecting rod (40) having oil splasher (60) formed thereon for intermittently engaging the oil within the enclosed oil reservoir (58) to splash lubricate the engine. The engine (30) is provided with a cylinder head (42) assembly defining a compact combustion chamber (44) having a pair of overhead intake exhaust ports (46, 52) cooperating intake and exhaust valves (50, 56). A lightweight high powered engine (30) is thereby provided having relatively low HC and CO emissions. <IMAGE>