| 摘要 |
PROBLEM TO BE SOLVED: To suppress drop in the negative pressure in a vacuum servo unit for braking force through the roughness control. SOLUTION: For a certain time after the start of an engine, an execution timer for the brake negative pressure securing control is held to an initial set value (for example, 20 sec), followed by down-counting. In this period, the brake negative pressure securing correction value is made '0', and when the execution timer gets '0', it is clipped to '0', while the brake negative pressure securing correction value is increased gradually, and when the brake negative pressure securing correction value becomes a value which cancels the roughness IG correction value, the execution timer setting flag is made '1', followed by resetting of the timer, and the brake negative pressure securing correction value is decreased gradually to '0'. After the execution timer has become '0', the negative pressure securing flag is set until the brake negative pressure securing correction value becomes '0', and in this period, the roughness control is stopped.
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