| 摘要 |
An internal combustion engine includes an exhaust gas recirculation control apparatus includes first and second normally closed valves having different flow areas which open to provide communication between a corresponding bank of an exhaust manifold and an intake manifold. Each valve is engaged to an actuator which reciprocates the valve between a fully open and fully closed position. Both actuators are independently operable under control of an ECU programmed to monitor operational parameters of a specific engine via sensors functionally engaged thereto to maintain the engine at a level of optimum performance, the ECU producing in response to sensor input, a no-flow level and an appropriate one of three possible active levels of recirculation. A no-flow level maintaining both valves closed allows no recirculation, an active first level maintaining both valves open allows maximum recirculation, an active second level maintaining a larger valve open allows less than maximum recirculation and an active third level maintaining a smaller valve open allows a level of recirculation greater than none.
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