EXHAUST CONTROL DEVICE FOR TWO-CYCLE ENGINE

摘要

PROBLEM TO BE SOLVED: To prevent the reduction of an engine output in a region where a low-speed area is shifted to a high-speed area and to improve an engine output characteristic over the whole operation region. SOLUTION: A pressure hole 1b for guiding the combustion pressure into a pressure chamber 13 from the inside of a cylinder is bored to an under case 9 from a cylinder block 1, and a pressure relief hole 19 opened into the pressure chamber 13 is bored on the side section of the under case 9. The pressure relief hole 19 is connected to one port of a duty solenoid valve 22 via a relief passage 21, and the other port is opened to the outside. The duty solenoid valve 22 is driven by an ECU 50 through a drive pulse signal having a duty ratio corresponding to the engine speed in the intermediate region where the low-speed area is shifted to the high-speed area. The exhaust timing is controlled at an optimum value to prevent the reduction of the engine output by relieving the combustion pressure guided into the pressure chamber 13 to control the operation pressure of a control valve element 6.