| 摘要 |
<p>PURPOSE:To improve the maximal output performance of the engine by controlling the negative pressure from a negative pressure source in accordance with a signal corresponding to a maximal supercharging pressure set in corresponding relation to the in-fuel alcohol concentration to thereby control the supercharging pressure of a supercharger. CONSTITUTION:CPU 42 calculates the in-fuel alcohol concentration from an output signal of an alcohol concentration sensor 26 and sets the duty ratio of a duty signal to a duty solenoid valve 21, to generate an output signal to a duty solenoid valve 21. In this case, as the in-fuel alcohol concentration becomes higher, a duty signal having the higher duty ratio is applied to a solenoid coil 21d to increase the closure time length of an atmospheric port 21a per unit of time to thereby decrease the leaking amount of the negative pressure, from a vacuum pump 48, which acts on an operation chamber 17b of a first diaphragm actuator 17 via a negative pressure passage 19. The negative pressure acting on this operation chamber 17b is thereby increased to cause an increase chamber 17b is thereby increased to cause an increase in magnitude of the force capable of closing a waste gate valve 15.</p> |
