Patent ID: 7299904

Claim:
A brake fluid pressure maintaining apparatus for a vehicle, comprising: a master cylinder for generating a brake fluid pressure when a driver steps on a brake pedal; a check valve interposed between the master cylinder and a wheel brake operatable by the brake fluid pressure from the master cylinder for allowing the flow of the brake fluid pressure from the master cylinder to the wheel brake in a braking operation; and, a normally-open electromagnetic valve closable in order to temporarily maintain the brake fluid pressure of the wheel brake even after release of stepping on the brake pedal, wherein the normally-open electromagnetic valve includes an electromagnetic coil for generating an electromagnetic force when a current is applied thereto, a fixed core to be immovably disposed, and a movable core to be attracted to the fixed core, and in a brake fluid pressure maintaining state, the normally-open electromagnetic valve is closed due to the electromagnetic force to thereby prevent the return of the brake fluid pressure from the wheel brake to the master cylinder and, in a brake fluid pressure no-maintaining state, the normally-open electromagnetic valve is always opened to thereby allow the flow of the brake fluid pressure from the master cylinder to the wheel brake or the return of the brake fluid pressure from the wheel brake to the master cylinder, and wherein the normally-open electromagnetic valve is controllable as follows: when it is detected that the vehicle is stopped, the electromagnetic coil is energized and the normally-open electromagnetic valve is closed; by changing the value of the current to be applied to the electromagnetic coil, an attracting force for closing the normally-open electromagnetic valve is changed; and by setting the attracting force at a given value, the brake fluid pressure to be maintained on the wheel brake side is set; wherein, when the normally-open electromagnetic valve is closed due to application of a current to the electromagnetic coil, in case where the brake fluid pressure of the wheel brake is higher than the attracting force of the given value, the normally-open electromagnetic valve is opened against the attracting force to thereby reduce the brake fluid pressure of the wheel brake down to the given value.