| 摘要 |
PURPOSE:To improve combustion efficiency over a wide range by securing the proper scavenging area and the strength of swirl in accordance with the engine operation condition by installing a swirl controller for partially opening and closing a scavenging hole from the lower part onto the outer peripheral part of a cylinder in rotatable and slidable ways. CONSTITUTION:A scavenging hole 41 is directed in the eccentric direction with respect to the axis center of a cylinder 4 so that a proper swirl is generated in the flow of scavenged gas. The inflow angles thetaa and thetab in the upper and lower parts of the scavenging hole 41 are set in the following relation: thetaa>thetab. In the above, a variable swirl apparatus 7 is installed, and a control part 71 for partially covering and opening and closing the scavenging hole 41 is installed. The driving part 72 of the above-described apparatus 7 is driven by a motor 74 through a hook 73. When the variable swirl apparatus 7 is shifted, for example, leftward, and the lower part area of the scavenging hole 41 is largely covered by the control part 71, the area of the part where the inflow angle thetaa of the upper part is large increases, and the scavenged gas in a strong swirl can be obtained.
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