| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To stabilize a combustion state while improving exhaust emission by the blowback of exhaust gas. <P>SOLUTION: An exhaust valve early closing control produces the blowback of the exhaust gas in an intake system. When the exhaust valve early closing control is performed, for example, during a first idle operation immediately after the starting, the blowback amount of the exhaust gas is becomes excessive. To prevent this problem, an ECU 50 prohibits the exhaust valve early closing control when the increased amount after the starting is reduced below a lower limit determination value, and is moved to a normal valve timing control. Therefore, an allowance is provided to the combustion state, and the exhaust emission can be improved by the exhaust valve early closing control in a period in which the discharged amount of HC is increased. When the increased amount after the starting is reduced, the exhaust valve early closing control is prohibited to stabilize the combustion state. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
