| 摘要 |
PURPOSE:To enable accurate control with no operation lag, by providing a by-pass valve between the output port of a spark advancement control valve and an intake pressure port, and to heighten reliability, by preventing the diaphragms of the control valve from returning. CONSTITUTION:When the rotational frequency of an engine is increased by opening a throttle valve 3, positive pressure is applied to the interior of an intake pipe 6 by the action of a turbo-fan 1 and the positive pressure in a surge tank 4 is applied to a cut valve 13 and a by-pass valve 17 and the positive pressure at an advance port 2 is applied to another cut valve 8. The diaphragm mechanisms of the valves 8, 13 are operated by the high pressure applied to input ports 9, 14 to shut off these ports and connect output ports 10, 15 to the atmosphere. As a result, no positive pressure is applied to the first and second chambers 38, 29 of a spark advancement control valve 11 so that diaphragm 37, 40 are actuated neither forward nor backward. The diaphragms 37, 40 are thus prevented by the valves 8, 13 from returning. When positive pressure is applied to the chamber 50 of the valve 17, the chamber 50 is connected to an output chamber 61 and a negative pressure port 22 is closed and the pressure in the tank 4 is transmitted to a spark advancement mechanism 20 to control spark advancement. |
