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When an electrical fluid pressure generator fails and a wheel cylinder is operated by brake fluid pressure generated by a master cylinder, if a first fluid pressure system leading to a rear fluid chamber of the electrical fluid pressure generator fails and is opened to the atmosphere, braking is per

When an electrical fluid pressure generator fails and a wheel cylinder is operated by brake fluid pressure generated by a master cylinder, if a first fluid pressure system leading to a rear fluid chamber of the electrical fluid pressure generator fails and is opened to the atmosphere, braking is performed by brake fluid pressure of a second fluid pressure system transmitted from the master cylinder through a front fluid chamber of the electrical fluid pressure generator to a wheel cylinder. At this time, a front supply port, which communicates through a front second cup seal, does not communicate with the master cylinder but with a reservoir. Such configuration prevents leakage of the brake fluid pressure generated by the master cylinder through the front supply port, the front second cup seal and the rear fluid chamber, thereby ensuring braking by the second fluid pressure system.

대표청구항 ▼

1. A brake system comprising: a master cylinder for generating brake fluid pressure based on braking operation of a driver;an electrical fluid pressure generator communicating with the master cylinder, and having a rear fluid chamber and a front fluid chamber generating brake fluid pressure by an el

1. A brake system comprising: a master cylinder for generating brake fluid pressure based on braking operation of a driver;an electrical fluid pressure generator communicating with the master cylinder, and having a rear fluid chamber and a front fluid chamber generating brake fluid pressure by an electrically controllable actuator; anda plurality of wheel cylinders communicating with the rear fluid chamber and the front fluid chamber, respectively, and generating a braking force for braking wheels so that when the electrical fluid pressure generator fails, the wheel cylinders are operated by the brake fluid pressure generated by the master cylinder;the electrical fluid pressure generator including:a rear piston and a front piston which are advanced by the actuator to generate brake fluid pressure in the rear fluid chamber and the front fluid chamber, respectively;a rear inlet port and a rear outlet port which are formed in the rear fluid chamber and connected to the master cylinder and the wheel cylinder, respectively;a front inlet port and a front outlet port which are formed in the front fluid chamber and connected to the master cylinder and the wheel cylinder, respectively;a rear first cup seal arranged at a front end of the rear piston so as to face forward;a rear second cup seal arranged at a rear end of the rear piston so as to face forward;a front first cup seal arranged at a front end of the front piston so as to face forward;a front second cup seal arranged at a rear end of the front piston so as to face rearward; anda rear supply port formed adjacent to and in the rear of the rear inlet port, and a front supply port formed adjacent to and in the rear of the front inlet port, the rear and front supply ports being connected to a reservoir. 2. The brake system according to claim 1, further comprising an anti-lock braking system (“ABS”) provided between the electrical fluid pressure generator and the wheel cylinder, the ABS decreasing, maintaining and increasing brake fluid pressure transmitted to the wheel cylinder in order to suppress locking of a wheel upon braking. 3. The brake system according to claim 2, further comprising a shutoff valve provided between the master cylinder and the electrical fluid pressure generator, the shutoff valve being closed at least during operation of the ABS. 4. The brake system according to claim 1, wherein a fluid passage extended from the rear supply port and another fluid passage extended from the front supply port are connected together into a single fluid passage which is connected to the reservoir of the master cylinder. 5. The brake system according to claim 1, further comprising a fluid pressure sensor for detecting brake fluid pressure generated by the master cylinder, and which is provided in a fluid pressure system in which a stroke simulator is arranged. 6. A brake system comprising: a master cylinder for generating brake fluid pressure based on braking operation of a driver;an electrical fluid pressure generator communicating with the master cylinder, and having a rear fluid chamber and a front fluid chamber generating brake fluid pressure by an electrically controllable actuator; anda plurality of wheel cylinders communicating with the rear fluid chamber and the front fluid chamber, respectively, and generating a braking force for braking wheels so that when the electrical fluid pressure generator fails, the wheel cylinders are operated by the brake fluid pressure generated by the master cylinder;the electrical fluid pressure generator including:a rear piston and a front piston which are advanced by the actuator to generate brake fluid pressure in the rear fluid chamber and the front fluid chamber, respectively;a rear inlet port and a rear outlet port which are formed in the rear fluid chamber and connected to the master cylinder and the wheel cylinder, respectively;a front inlet port and a front outlet port which are formed in the front fluid chamber and connected to the master cylinder and the wheel cylinder, respectively;a rear first cup seal arranged at a front end of the rear piston so as to face forward;a rear second cup seal arranged at a rear end of the rear piston so as to face forward;a front first cup seal arranged at a front end of the front piston so as to face forward;a front second cup seal arranged at a rear end of the front piston so as to face rearward; anda means for preventing leakage of the brake fluid of the front fluid chamber through the rear fluid chamber;wherein the means for preventing leakage of the brake fluid of the front fluid chamber through the rear fluid chamber comprises a rear supply port formed adjacent to and in the rear of the rear inlet port, and a front supply port formed adjacent to and in the rear of the front inlet port, the rear and front supply ports being connected to a reservoir. 7. The brake system according to claim 6, wherein the reservoir is connected to the master cylinder, and a fluid passage extended from the rear supply port and another fluid passage extended from the front supply port are connected together into a single fluid passage which is connected to the reservoir. 8. The brake system according to claim 6, further comprising a fluid pressure sensor for detecting brake fluid pressure generated by the master cylinder, and which is provided in a fluid pressure system in which a stroke simulator is arranged.