Two-stroke engine

A two-stroke engine including a two-stroke engine in a portable handheld work apparatus, the two-stroke engine comprising:

• a cylinder having a cylinder wall;
• a piston mounted in said cylinder to undergo a reciprocating movement along a stroke path between top dead center and bottom dead center 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;
• a mixture-preparation device for supplying an air/fuel mixture;
• an intake channel for conducting said air/fuel mixture into said crankcase;
• said cylinder having a discharge opening formed therein;
• a plurality of transfer channels connecting said crankcase to said combustion chamber;
• a first portion of said transfer channels being disposed on one side of a symmetry plane extending through said cylinder so as to partition said discharge outlet;
• a second portion of said transfer channels disposed on the other side of said symmetry plane;
• each of said transfer channels having a first end defining an entry window opening into said combustion chamber;
• said entry window being formed in said cylinder wall and being controlled by said piston as said piston moves in said cylinder;
• each of said transfer channels having a second end opening into said crankcase;
• a first plurality of air channels connected to corresponding ones of said first portion of transfer channels;
• a second plurality of air channels connected to corresponding ones of said second portion of said transfer channels;
• gas supply means for supplying a gas flow to each of said air channels;
• said first plurality of air channels being configured separately from each other so that the volumes of the gas flows thereto can be adjusted differently;
• said second plurality of air channels being configured separately from each other so that the volumes of the gas flows thereto can be adjusted differently;
• a check valve for connecting each of said air channels to the transfer channel corresponding thereto at a location between said first and second ends thereof so as to permit the gas flow to flow from said air channel into the transfer channel;
• and,
• a throttle device connected to said air channels for effecting the different adjustment of the volumes of the gas flows in the separately configured air channels.