| 摘要 |
PURPOSE:To secure smooth stationary operation, by connecting a stationary operation detector to a drive signal generation circuit for a solenoid valve for opening and closing an air bleed passage, to cause the circuit to produce a drive signal of second constant frequency in stationary operation to suppress torque fluctuation. CONSTITUTION:When a throttle valve 11 is opened for acceleration, a negative pressure port 60 is opened into an intake passage 7 downstream to the throttle valve to apply negative pressure to the port to intensify the negative pressure in the first chamber 65 of a delay valve 62. However, a check valve 67 is closed so that the negative pressure in a negative pressure chamber 70 remains weak and a movable contact 73 is kept off a fixed contact 74 for a period of time. For the period of the low opening degree of the throttle valve 11 and for the period of time after its opening, a saw-tooth voltage of 1Hz to 2Hz in frequency is applied to a voltage-current converter 55 so that the cross-sectional area of the opening of a valve port 37 changes in a saw-toothed manner in proportion to the electrical current of a solenoid 43. For that reason, the air fuel ratio of a mixture fluctuates smoothly so that the state of combustion does not sharply change. Stable combustion is thus always secured regardless of the operating condition of an engine. |
