| abstract |
The invention describes a hand-held power tool (20) adapted to be carried by a user during use. The power tool (20) has a frame (22) comprising a handle (24, 26) held by the user, an instrument (32) fixed to said frame (22) having a rotary input element (64), as well as a small internal combustion aluminum four-stroke engine (30) fixed to the chassis, in order to activate the instrument. A crankshaft (36) is leveled on the engine block, so as to rotate around a crankshaft axis. A piston (38) moves back and forth inside the bore (34) and is coupled to the crankshaft by means of a coupling rod (40) on which is located an oil nozzle (60) for intermittently introducing the oil inside the oil tank (58) placed in an enclosure, so as to lubricate the engine. The engine (30) is provided with a cylinder head assembly (42) defining a compact combustion chamber (44) having a pair of exhaust and intake ports (46, 52) located in the cooperating upper part with the intake and exhaust valves (50, 56). The invention makes it possible to produce a light and high power engine (30) producing relatively low hydrocarbon and carbon monoxide emissions. |