| 摘要 |
PURPOSE:To reduce production of vibration and noise of an engine and to prevent production of white smoke in exhaust gas, by a method wherein, even at high lands, an absolute pressure in an intake air pipe is ensured at a specified value or more in a state to hold an intake air throttle at a specified state through recirculation of intake gas. CONSTITUTION:An electronic control unit 42 stores a computing result by means of a signal from each sensor ad an EGR instruction value when a diesel engine 10 is not in an idling state. When it is in an idling state, an intake air throttle is in an ON-state, and when an intake air pressure in an intake air pipe 12 is higher than a given value K1, the minimum value of a calculated EGR instruction value is outputted to a negative pressure regulating valve 32 to control an EGR amount. When an intake air pressure is not higher then a given value K2 (K2>K1), an EGR instruction value is increased, control is made until the intake air pressure is increased over the given value K2. Thus, since the intake air pressure is controlled not only by the throttle valve but also by an EGR valve 18, even when the engine is in an idling state at highlands, the intake air pressure is increased to a given value or more, a production of vibration and noise of the engine can be reduced, and a further advantageous measure to counter exhaust of HC and white smoke and failure in ignition can be taken.
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