Master cylinder for brake system

1. A master cylinder for brake systems including a cylinder body having a bore therein, a first and second piston installed in the bore to move forward and backward, and a first hydraulic pressure chamber and a second hydraulic pressure chamber adapted to be pressed respectively by the first and second pistons, the first and second hydraulic pressure chambers being divided from each other in the bore, the master cylinder comprising:

a pressure regulating channel to connect the first hydraulic pressure chamber to the second hydraulic pressure chamber to reduce pressure difference between the first hydraulic pressure chamber and the second hydraulic pressure chamber, and a flow control valve provided in the pressure regulating channel to open and close the pressure regulating channel according to the pressure difference between the first hydraulic pressure chamber and the second hydraulic pressure chamber,

wherein:

the first hydraulic pressure chamber is provided with a large hydraulic pressure chamber expanded to an inside of the cylinder body, and a small hydraulic pressure chamber smaller than the large hydraulic pressure chamber; and

the cylinder body is provided with a first oil introduction port to supply oil to the first hydraulic pressure chamber and a second oil introduction port to supply oil to the second hydraulic pressure chamber,

wherein each of the first and second oil introduction ports is provided with a check valve,

wherein the check valve of the first oil introduction port is closed at an initial stage of braking, and opened after a predetermined portion of hydraulic pressure in the large hydraulic pressure chamber is discharged, and

wherein the pressure regulating channel allows the large hydraulic pressure chamber of the first hydraulic pressure chamber and the second hydraulic pressure chamber to communicate with each other therethrough.

2. The master cylinder according to claim 1 , wherein the first piston is provided with a first step portion extending a distance corresponding to a length of the large hydraulic pressure chamber to apply pressure to the large hydraulic pressure chamber, and a second step portion formed to apply pressure to the small hydraulic pressure chamber.

3. The master cylinder according to claim 1 , wherein the pressure regulating channel is formed in the cylinder body.

4. The master cylinder according to claim 3 , wherein the pressure regulating channel is formed by drilling through the cylinder body, and the opening made by drilling is closed by a covering member.

5. The master cylinder according to claim 1 , wherein the flow control valve is one of a normally-open type solenoid valve and a normally-closed type solenoid valve having a function of the check valve to control flow through the pressure regulating channel and prevent backflow of hydraulic pressure from the second hydraulic pressure chamber to the first hydraulic pressure chamber.

6. A master cylinder for brake systems including a cylinder body having a bore therein, a first and second piston installed in the bore to move forward and backward, and a first hydraulic pressure chamber and a second hydraulic pressure chamber adapted to be pressed respectively by the first and second pistons, the first and second hydraulic pressure chambers being divided from each other in the bore, the master cylinder comprising:

a pressure regulating channel to connect the first hydraulic pressure chamber to the second hydraulic pressure chamber to reduce pressure difference between the first hydraulic pressure chamber and the second hydraulic pressure chamber, and a flow control valve provided in the pressure regulating channel to open and close the pressure regulating channel according to the pressure difference between the first hydraulic pressure chamber and the second hydraulic pressure chamber,

wherein:

the first hydraulic pressure chamber is provided with a large hydraulic pressure chamber expanded to an inside of the cylinder body, and a small hydraulic pressure chamber smaller than the large hydraulic pressure chamber; and

the cylinder body is provided with a first oil introduction port to supply oil to the first hydraulic pressure chamber and a second oil introduction port to supply oil to the second hydraulic pressure chamber,

wherein each of the first and second oil introduction ports is provided with a check valve,

wherein the check valve of the first oil introduction port is closed at an initial stage of braking, and opened after a predetermined portion of hydraulic pressure in the large hydraulic pressure chamber is discharged, and

wherein the flow control valve is one of a normally-open type solenoid valve and a normally-closed type solenoid valve having a function of the check valve to control flow through the pressure regulating channel and prevent backflow of hydraulic pressure from the second hydraulic pressure chamber to the first hydraulic pressure chamber.

7. The master cylinder according to claim 6 , wherein the first piston is provided with a first step portion extending a distance corresponding to a length of the large hydraulic pressure chamber to apply pressure to the large hydraulic pressure chamber, and a second step portion formed to apply pressure to the small hydraulic pressure chamber.

8. The master cylinder according to claim 6 , wherein the pressure regulating channel is formed in the cylinder body.

9. The master cylinder according to claim 8 , wherein the pressure regulating channel is formed by drilling through the cylinder body, and the opening made by drilling is closed by a covering member.

10. The master cylinder according to claim 6 , wherein the pressure regulating channel allows the large hydraulic pressure chamber of the first hydraulic pressure chamber and the second hydraulic pressure chamber to communicate with each other therethrough.