| 摘要 |
<p>A carburettor for a two-stroke engine includes a substantially circular section flow duct comprising rich (42) and lean (44) flow passages in parallel, through which, in use, air flows in a flow direction and which are separated by a substantially planar partition (66). At least one fuel jet (60, 61, 62) communicates with the rich passage (42) and the partition (66) includes an aperture (68) towards which the fuel jet is directed. A substantially planar butterfly valve (20) is received in the aperture (68) so as to be pivotable between a first position, in which the flow duct is substantially closed, and a second position, in which the flow duct is substantially open. The butterfly valve (20) is carried by a pivotal shaft (2) mounted to pivot about an axis which extends through the flow duct substantially diametrically. The butterfly valve (20) is connected to the pivotal shaft (2) such that, when it is in the second position, its plane is parallel to the diametral plane in which the said axis lies but is offset from it in a direction towards the rich passage. The plane of the planar partition (66) is also parallel to the said diametral plane but offset from it in a direction towards the rich passage. The cross-sectional area of the lean flow passage is therefore greater than that of the rich flow passage.</p> |
