JPS6483821A - Supercharge pressure control device for engine - Google Patents

Abstract

PURPOSE:To improve combustibility by increasing a supercharge pressure enhancing a scavenge effect in the beginning of intake when knocking is detected in an intermediate load range, in the case of an engine scavenging exhaust gas in a combustion chamber by supercharge air when the opening period of intake and exhaust ports overlaps. CONSTITUTION:The opening and closing timing of intake and exhaust valves 11, 12 is set in a manner wherein the opening timing of intake and exhaust ports 4, 5, opened to a combustion chamber of each cylinder, is overlapped for the predetermined period. An intake passage 14, communicating with the intake port 4, provides a mechanical supercharger 18 in the downstream side of a throttle valve 15 while a bypass passage 19, interposing a bypass valve 20, detouring around this supercharger 18. While an engine 1 provides a knocking sensor 13, and its output signal is input to a control unit 21. When knocking is detected in an intermediate load range, the engine closes the bypass valve 20 so as to increase a supercharge pressure in the initial period of intake while controls a throttle valve 10 so as to throttle its opening.