Patent ID: 6976458

Claim:
An internal combustion engine for a portable handheld work apparatus including a motor-driven chain saw, cutoff machine, brushcutter or the like, the internal combustion engine comprising: a cylinder; a piston mounted in said cylinder to undergo a reciprocating movement along a stroke path during operation of said engine; said cylinder and said piston conjointly delimiting a combustion chamber; a crankcase connected to said cylinder; a crankshaft rotatably mounted in said crankcase; a connecting rod connecting said piston to said crankshaft to permit said piston to drive said crankshaft as said piston reciprocates in said cylinder; an outlet for conducting exhaust gases away from said combustion chamber; at least one transfer channel for connecting said crankcase to said combustion chamber at pregiven positions of said piston; said transfer channel defining a transfer window opening into said combustion chamber; an ancillary channel having a first end opening into said combustion chamber and a second end opening into said transfer channel; said ancillary channel being open to said combustion chamber in a pregiven operating state during a downward stroke of said piston while said transfer window to said combustion chamber is still closed; and, means for opening said ancillary channel during idle and part load and for closing said ancillary channel during full load.