| 摘要 |
PURPOSE:To make improvements in responsiveness at the time of transition to a supercharging operating state by making a second supercharger prerotatable at a driving range where it is set to a dormant state, in an engine which is provided with a first supercharger normally driven and the second supercharger being driven only at a specified driving range. CONSTITUTION:At a low-speed, low rotation range, an exhaust cut valve 5 is closed, and a first supercharger 1 alone is operated. In this case, when a driving state has shifted to the high flow side from the low flow side, first an exhaust shifting valve 8 is selected to open from close, then a relief valve 24 to open from close as well, and also the exhaust cut valve 5 to open from close in order, respectively. With this operation, a second supercharger 2 is operated, thereby enhancing the extent of supercharging efficiency at the high flow range. In brief, at time of the said transition, in advance of open operation of the exhaust cut valve 5, an exhaust shifting valve 11 is opened where by the second supercharger 2 is made into prerotation, and afterward, the relief valve 24 is closed, thus an increase in rotational frequency of the second supercharger 2 during prerotation is accelerated, and the said transition is smoothly performed with no shock. |
