Ignition timing control system for an internal combustion engine

摘要

An ignition timing control system for an internal combustion engine, including a vacuum actuator connected to turn a point base about the axis of the rotary cam which operates the breaker points to advance or retard the ignition timing. The vacuum actuator employs two vacuum chambers, one used primarily to advance the timing, the other used to retard the timing. Each chamber communicates with an engine intake passage downstream from a throttle valve. Electromagnetic selector valves, one associated with each vacuum chamber, serve to connect each vacuum chamber to the engine intake passage, or alternatively to vent each vacuum chamber to atmosphere. These selector valves may be energized by a temperature switch, a velocity switch or a cruise switch. A check valve maintains vacuum intensity in the spark advance chamber when the vacuum intensity at the engine intake passage is lowered by virtue of the opening of the throttle valve.