| 摘要 |
PROBLEM TO BE SOLVED: To prevent an output of a vacuum booster from being lowered rapidly after a brake operation is canceled while a solenoid is being driven by making a drive circuit to receive a detecting signal of a release switch which detects the cancellation of the brake operation and to make the solenoid to perform a duty operation so as to cancel the booster operation while the solenoid is under operation. SOLUTION: When a release switch is sending an ON signal according to a treadle operation of a brake pedal, if a treadle speed of the brake pedal is larger than the predetermined value Sa, it is judged by a detecting means whether or not a pedal stroke is larger than the predetermined value Sb. If the pedal stroke is larger than the predetermined value Sb, the brake pedal operation is judged to be a quick service so that a solenoid is driven to apply a brake to a vehicle. When the release switch is sending an OFF signal according to the cancellation of treadle of the brake pedal, the solenoid is switched to a duty operation. If a duty operation time is equal to or larger than the predetermined value t α, an output of a vacuum booster device is judged to be null so that the drive of the solenoid is stopped. |
