| 摘要 |
PURPOSE:To enable a rapid change of combustion pressure to be prevented, by advancing ignition timing at idle operation through an advance control side negative pressure chamber receiving intake manifold negative pressure while retarding the ignition timing at deceleration through a delay control side negative pressure chamber receiving the intake manifold negative pressure. CONSTITUTION:A vacuum control 12 comprises an advance control side negative pressure chamber 7, formed by the upper part of a case 10 and the first diaphragm 16 used as a movable partition, and a delay control side negative pressure chamber 9, formed by the bottom part of the case 10 and the second diaphragm 17. The advance control side negative pressure chamber is communicated to the upstream vicinity D of a throttle valve in a carburetor 2 through the first air path 6. The delay control side negative pressure chamber is connected to the vicinity D through the second air path having a restrictor. In this way, a rapid change of combustion pressure is prevented by advancing ignition timing to improve fuel consumption at idle operation while by delaying the ignition timing at deceleration. |
