| 摘要 |
PURPOSE:To make small the rise of temperature of supercharge air to enhance the efficiency of air charge into a combustion cylinder, by providing, in a supercharging cylinder, a communication means for communicating the inside of the supercharging cylinder with an intake-air port upstream of an intake-air valve in the supercharging cylinder in the intermediate and low ranges of the internal- combustion engine. CONSTITUTION:Air is sucked from an air-cleaner 17 into a second cylinder 3 as a supercharging cylinder in which air is compressed and from which air is then alternately fed into a first cylinder 2 and a third cylinder 4 as combustion cylinders. Although the supply of supercharge air from the secondary cylinder 3 into the first 2 and third cylinders 4 becomes excessive upon full closing of a throttle valve 22, if the pressure of the inside of an intake-air manifold 21 increases in the negative direction due to closing of the throttle valve 22, a supercharge control valve 25 opens a communication passage 24 so that a part of air which is to be compressed due to ascending of a piston in the second cylinder 3 is relieved from the communication passage 24 to a part upstream of an intake-air valve 13. |
