| 摘要 |
PURPOSE:To match supercharging pressure to an inner compression ratio so as to prevent generation of pulsation and noise by changing the inner compression ratio of a mechanical supercharger on the basis of at least supercharging pressure and an engine speed. CONSTITUTION:A mechanical supercharger SC, an intercooler IC and a throttle valve VTH are interposed in order on the way of an intake passage 1 in an engine main body E from the upstream thereof. A bypass valve VBP is interposed on the bypass passage 3 of the intake passage 1. A switching valve V is interposed so that it can switch freely in an alternative way communication and shutting between a passage 54 opened to the atmosphere and leading pipes 51 and 52. The switching valve V and a bypass valve driving means 55 are controlled by a control means C. In this case, switching operation of the switching valve V, namely, switching of the inner compression ratio of the supercharger SC, is controlled according to supercharging pressure and the engine speed. |
