| 摘要 |
PURPOSE:To maintain at high level the exhaust gas pressure to be applied to a turbine of a primary turbo supercharger by stopping for a certain period the operation of a relief means when a secondary turbo supercharger is changed over from operation into out of operation. CONSTITUTION:A solenoid type three-way valve 245 and a solenoid 253 are turned from off to on by a control unit 246 after elapse of a certain period on the occasion of transition from the high suction air amount range to the low suction air amount range. Thereby a waste gate valve 227 and an exhaust gas leak valve 230 are shut forcedly during this period, and no exhaust gas relief will take place. In case therefore the suction air amount is once increased and then decreased for ex. at the time of reacceleration or shifting-up under acceleration, to be followed by increasing again, the exhaust gas pressure applied to a turbine 205 of a primary turbo supercharger 204 is maintained high, and the turbo lag of the turbo supercharger 204 is suppressed when the suction air amount is increased again, which provides operation with good rising characteristic to ensure enhancement of the running characteristic. |
