| 摘要 |
PURPOSE:To reduce unnecessary air compression, reduce the consumption of power, and lower noise by providing a bypass flow passage having a selector valve which can discharge air into the atmosphere, in an intake flow passage. CONSTITUTION:At the time of a high load and low speed rotation, ports A-B are connected and the auxiliary discharge port of a screw type mechanical supercharger 11a which is connected to a bypass flow passage 16 is operated to reduce an inside pressure ratio. At the time of a high load and high speed rotation, both ports A-B and ports A-C are shut off and connected to an intake passage 12 for increasing the inside pressure ratio. At the time of a medium load and a low load, the ports A-C are connected and, when a discharged air quantity is too large compared with the required air quantity and the pressure of the intake passage 12 is higher than the pressure at the port C, air is discharged into the atmosphere through a relief valve 17.
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