| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve the response characteristic of valve timing control to a variations in control signal (duty value) for a oil-pressure control valve of a variable valve timing device. <P>SOLUTION: The duty value is computed in accordance with the deviation of target valve timing and actual valve timing, and the duty value is vibrated at a specified amplitude. At this time, the amplitude of the duty value is set at more than a half of the width of a region (dead band) where the responsiveness of valve timing to the variations in the duty value is extremely slow. Consequently, it is possible to change the valve timing favorable in responsiveness against the variations in the duty value (vibration central value) when changing the duty value (vibration central value) from a holding duty value (neighborhood of the center of the dead band) in accordance with variations of the target valve timing as it is possible to extend a vibration range of the duty value to a region favorable in responsiveness outside the dead band even when the vibration central value of the duty value is in the neighborhood of the center of the dead band. <P>COPYRIGHT: (C)2004,JPO</p> |
