| 摘要 |
PURPOSE:To prevent a large shift that is to be produced temporarily from the target value by counting the control pulses produced while the same drive mode lasts to perform the normal control when the number of control pulses is less than a set level and then to set a holding mode if the number of control pulses exceeds the set level respectively. CONSTITUTION:A control pulse width deciding means 6 decide the control pulse width against a drive means 2 in response to the deviation between an actual position and the target position. A drive signal generating means 9 sets a drive mode to a holding mode when it is decided by a comparing means 8 that the number of control pulses exceeds a set level. Thus it is possible to limit the negative pressure that is stored at the negative pressure side owing to a temporary defect. In other words, a control pulse counting means 7 counts the control pulses in a state where the opening position of a throttle valve has no change in the same drive mode. Then the means 9 switches the drive mode to the holding mode when it is decided by the means 8 that the number of control pulses reaches the set level. Then the holding mode is changed to a normal control mode when the opening position of the throttle valve has a change.
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