| 摘要 |
PURPOSE:To improve combustion efficiency during idling by interposing a 3-way solenoid valve having an atmosphere side opening in a vacuum pipe communicating between an actuator for driving a suction throttle valve and a vacuum pump, and by controlling the duty of said valve according to the wall temperature of a combustion chamber. CONSTITUTION:In an engine where a suction throttle valve 8 opened or closed with a vacuum response type actuator 10 operated by vacuum introduced from a vacuum pump 9 is interposed in a suction pipe 7, a 3-way solenoid valve 12 is interposed in the middle of a vacuum pipe 11 communicating between the vacuum pump 9 and the actuator 10. The 3-way solenoid valve 12 is duty- controlled with a control device 13 when the engine is determined to be idling by an accelerator switch 5 so that the 3-way solenoid valve 12 is opened to the atmosphere to open the suction throttle valve 8 if the inside wall temperature of a combustion chamber 5 is determined with a wall temperature sensor 8 to be below a set value, while the suction throttle valve 8 is closed if the detected wall temperature is beyond the set value.
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