| 摘要 |
PURPOSE:To enhance the efficiency of supercharge, in an engine in which each cylinder has high load and low load intake-air ports and each port has an independent intake-air passage, by introducing supercharge air into a stream at a predetermined timing with the use of a shut-off valve in a high load intake-air passage so that the counter flow of exhaust gas due to negative pressure may be prevented. CONSTITUTION:Each cylinder 1 has an exhaust valve 3A and two intake-air valves consisting of a normally open low load operating intake-air valve which is not shown and a high load operating intake-air valve 2A connected to a high load suction air passage 6A disposed therein with a valve 8. When the valve 8 is closed by an actuator 11 upon low load operation, pressurized air from a supercharger 12 is fed into the passage 6A until the termination of an suction stroke. With this arrangement, negative pressure generated in the passage upon suction stroke may be eliminated to prevent the counter flow of exhaust gas due to the negative pressure upon valve overlap, and as well it is possible to aim at sufficiently utilizing supercharge air. |
