| 摘要 |
The invention relates to a port-controlled two-stroke engine with valve timing which varies as a function of the engine speed. In two-stroke engines of known type the position of the control ports and the valve timings are constant over the entire speed range and represent a compromise between the demands on the individual speed ranges. The subject of the present invention is an arrangement which permits the speed-related adjustment of the valve timings to the particular demands. This is achieved by a speed-related, axial displacement of the cylinder (13) and hence of the control ports (20, 42) in relation to the piston dead centres by the amount (X, Y). The cylinder head (30, 30'), carried by support elements (29), rests independently of the cylinder (13) on the crank casing (12) and ensures a constant compression ratio over the entire adjustment range. The piston-shaped section (30') of the cylinder head (30) is immersed in the cylinder bore (13') and provides for sealing of the combustion chamber. The sealing off of the cylinder (13) from the crank casing (12) is achieved by profiled elements (21') positively interlocking with one another. By means of this arrangement an improved power output is obtained. <IMAGE>
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