| 摘要 |
PURPOSE:To prevent an engine from generating its short output and excessive output due to a change in a passage size, by providing a target supercharge pressure changing means which changes the target supercharge pressure for an operating condition of the engine through a size changing device adjusting a size. CONSTITUTION:Gas is introduced to a turbine 9 from a low speed exhaust gas introducing passage 16 when an engine is in low speed operation, while a selector valve 18 opens a high speed exhaust gas introducing passage 17 by opening a control valve 31 when the engine is in high speed operation. A target supercharge pressure P0 is set by a waste gate valve 21. A computer 25 opens a control valve 36 relieving the supercharge pressure in a relief passage in a low speed range A if the supercharge pressure detected by a pressure sensor 27 increases to a value Pmax. When a passage changes its contour from small size to large size by opening the selector valve 18, the target supercharge pressure P0 is decreased by a predetermined value DELTAPmax for the maximum supercharge pressure Pmax in the low speed range. |
