| 摘要 |
PURPOSE:To make brake reaction force small in the initial stage of booster operation and obtain good brake feeling by so constructing a fluid pressure booster that its output rises at a large servo ratio in the initial stage of operation of the fluid pressure booster, and that it rises at a small servo ratio after a specified point of time after operation is started. CONSTITUTION:A fluid pressure booster possesses a power chamber 6 and a low pressure chamber 7 comparted in the rear and in the front of a power piston 2 that interlocks with a master cylinder and inside a housing 1, fluid whose fluid pressure responds to the input applied to an input shaft 9 is supplied from a control valve 10 to the power chamber 6, and the low pressure chamber 7 is connected to a reservoir by means of a discharge passage (1b). A proportioning valve (P valve) 31 that controls opening/closing of the communication between the low pressure chamber 7 and the reservoir is provided in this discharge passage (1b). And the pressure of the power chamber 6 is forced to act on the side of the small diameter side of this P valve 31 and the pressure of the low pressure chamber 7 is forcod to act on the large diameter side respectively, thereby the P valve 31 is opened/closed and the fluid pressure inside the low pressure chamber 7 is raised at a specified rate when the pressure in the power chamber 6 is raised to a specified value or above. |
