| 摘要 |
A novel exhaust gas recirculation (EGR) control system comprises an EGR valve having an inlet control port connected through a normally closed solenoid-actuated valve to venturi vacuum tap of the caburetor. The solenoid-actuated valve is controllably energized via an electrical control circuit which monitors a number of engine operational characteristics. In the preferred embodiment, these monitored characteristics include: the amount of throttle blade opening; the magnitude of intake manifold vacuum; the relative durations of idle and non-idle operation during a immediately past time period; and the engine temperature. Individual electrical control signals are derived for each of the monitored characteristics and the value of each signal indicates whether the correspondingoperating characteristic is commanding the solenoid-actuated valve to be energized. The control circuit is so constructed that the solenoid-actuated valve is open, thereby permitting the EGR valve to be actuated, only if all the individual control signals are simultaneously commanding exhaust gas recirculation.
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