| 摘要 |
PURPOSE:To prevent the generation of combustion noise by reducing the quantity of lead angle of ignition timing at the time of EGR when the quantity of intake of new air becomes above a certain value. CONSTITUTION:When a throttle valve 3 is slightly opened from its totally closed condition, an intake negative pressure acts on a first negative pressure sensing port 10 as well as a second negative pressure sensing port 11. Thereby, since the intake negative pressure acts on the negative pressure chamber 6a of an actuator 6, an EGR valve 5 is opened to carry out EGR while, since the intake negative pressure also acts on the second negative pressure chamber 8d of an actuator 8, the angle of lead of an ignition timing is largely advanced accompanying the EGR. When the throttle valve 3 is further opened, since the intake negative pressure acts on a third negative pressure sensing port 12, the negative pressure is fed to the negative pressure chamber 18a of the actuator 18, causing the valve body 15a of a selector valve 15 to be displaced downward. As a result, the second negative pressure chamber 8d of the actuator 8 is released to the open air, correcting the lead angle of ignition timing accompanying the EGR to be small.
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