| 摘要 |
PURPOSE:To permit to control air-fuel ratio well even in highland by a method wherein vacuum in the downstream of a throttle valve is accumulated in an accumulator and the accumulated vacuum is utilized to obtain a gas control presure in accordance with the degree of the vacuum. CONSTITUTION:The throttle valve 5 is fully opened substantially upon the high load operation of the engine 4 and the vacuum Ps, which passes an orifice 40 located in a path 36 from a vacuum detecting hole 8, is reduced and closed to atmospheric pressure. Therefore, the vacuum Ps under the low load operation of the engine is accumulated into the accumulator 43 as an accumulated vacuum Pt. When the vacuum P2 of a vacuum valve chamber 33b is highly reduced suddenly, the vacuum Pt in the accumulator 43 is diluted by the vacuum Pv, acting into the valve chamber 32b from the vacuum detecting hole 9, through the path 36 and acts into the vacuum chamber 12a as the vacuum Pe. The vacuum Pe can open an air control valve 12 sufficiently, therefore, the amount of secondary air may be secured even upon the high load operation of the engine 4 in the highland. |
