| 摘要 |
PURPOSE:To enable ignition timing adjustment to be carried out in response to electric load variation by opening negative pressure passages respectively in upstream and downstream positions of a throttle valve staying in the idle opening position and switching those negative passages to a negative pressure chamber of lead angle device in response to the electric load variation. CONSTITUTION:Since a selector valve 6 is in the illustrated position when a throttle valve 3 is in the idle opening position, low negative pressure on the upstream side from the throttle valve 3 works on a negative pressure chamber 10 of a lead angle device 8, however, its ignition lead angle is small. On the other hand, when a headlight lighting switch 14, heater blower switch connected in series or in parallel to said switch 14 and other switches are thrown in, a solenoid 13 of the selector valve 6 is set conductive and said valve 6 is switched so as to connect the second negative pressure passage 5 to an introducing passage 7. From the above, high negative pressure on the downstream side from the throttle valve 3 works on the negative pressure chamber 10 to enlarge the ignition lead angle. |
