| 摘要 |
PURPOSE:To prevent the overrunning of a main turbocharger and protect a turbocharger by compulsorily opening an exhaust bypass valve in a no-loaded state. CONSTITUTION:It is detection-judged if an engine 1 is substantially in no-load state or not, from the gear position signal of a transmission, clutch signal, etc., and when the substantially no-load state is judged, an exhaust bypass valve 41 is always compulsorily opened. In a loaded state, the compulsory valve opening of the exhaust bypass valve 41 is not executed. Accordingly, before the no-load racing, the exhaust bypass valve 41 is in the compulsorily opened state, and even if racing is executed in this state, a portion of the exhaust gas is allowed to flow into a subturbocharger 8 side, and the quantity of the exhaust gas supplied to a main turbocharger 7 side is reduced by that portion, and the overrunning of the main turbocharger 7 is properly prevented. |
