Patent ID: 9522663
Filing Date: 2016-12-20
CPC Classification: B60T

Claim Text:
1. A hydraulic-pressure generator configured to provide a smooth brake feel when a brake pedal returns from a depressed state thereof, said hydraulic-pressure generator comprising: a cylinder tube having a cylindrical bore formed therein; a secondary piston which is operatively connected with a brake pedal and is which is disposed in, and configured to be displaced in the cylinder tube in response to movement of the brake pedal, the secondary piston having a second hollow formed therein, and a peripheral wall surrounding the second hollow; a primary piston which is disposed in, and configured to be displaced in the cylinder tube in response to displacement of the secondary piston, the primary piston having a first hollow formed therein, and a peripheral wall surrounding the first hollow; a first pressure chamber which is formed in the cylinder tube and which is configured so as to communicate with the first hollow formed in the primary piston, and to generate a first brake fluid hydraulic pressure corresponding to displacement of the primary piston; a second pressure chamber which is formed in the cylinder tube and which is configured so as to communicate with the second hollow formed in the secondary piston, and to generate a second brake fluid hydraulic pressure corresponding to displacement of the secondary piston; a reservoir which reserves brake fluid therein, and which communicates with the cylinder tube through a first relief port and a second relief port; wherein at least one first communication opening is formed in the peripheral wall of the primary piston, said at least one first communication opening configured to be switched between a first communicating state, in which the at least one first communication opening communicates with the first relief port, and a first non-communicating state in which the at least one first communication opening does not communicate with the first relief port; and at least one second communication opening is formed in the a peripheral wall of the secondary piston, said at least one second communication opening configured to be switched between a second communicating state, in which the at least one second communication opening communicates with the second relief port, and a second non-communicating state in which the at least one second communication opening does not communicate with the second relief port; wherein a total aperture area of the at least one first communication opening is different from a total aperture area of the at least one second communication opening, whereby a flow rate at which the brake fluid can flow through the at least one first communication opening is different from a flow rate at which the brake fluid can flow through the at least one second communication opening.