| 摘要 |
A system for controlling the ignition timing of an engine provided with a supercharger. The system comprises a vacuum advance device comprising two chambers defined by a diaphragm and a rod connecting the diaphragm to an advance mechanism of a distributor of the engine. The vacuum advance device is operated by the pressure in the intake passage at upstream side of the throttle valve of the engine and the pressure at a signal port provided on the wall of the intake passage at a position just above the throttle valve. The signal port is connected to one of the chambers. A solenoid operated three-way valve having three ports is provided. The three-way valve has a first port communicated with the other chamber of the vacuum advance device, a second port communicated with the intake passage at the upstream side of the throttle valve, and a third port communicated with the atmosphere. A thermo switch responsive to temperature of the engine is provided for operating the three-way valve so as to open the third port and to close the second port at temperature higher than a predetermined temperature and to close the third port and to open the second port at temperature lower than the predetermined temperature where knocking hardly occurs. The vacuum advance device is so arranged that the diaphragm is deflected by the pressure in the intake passage in the advance direction at the lower temperature conditions to provide advanced ignition timings. |
