| 摘要 |
<p>A two-stage master cylinder includes a housing with a stepped bore for receiving at least one piston. The one piston cooperates with the housing to substantially define a primary chamber communicating with a brake circuit and an auxiliary or fast- fill chamber. The auxiliary chamber is contracted during a braking application to communicate pressurized fluid to the primary chamber. A valve member is exposed to the fluid pressure within the primary chamber and the auxiliary chamber to communicate the latter with a reservoir. The valve member defines a first differential area and a second differential area which cooperate with the primary and auxiliary chambers, respectively, to meter the communication of fluid from the auxiliary chamber to the reservoir as the fluid pressure within the primary chamber is increasing. When the primary chamber is increasing in fluid pressure during a braking application, the fluid pressure within the auxiliary chamber is increasing or decreasing depending on the opening and closing of communication between the auxiliary chamber and the reservoir.</p> |
