| 摘要 |
PURPOSE:To contrive to let air flow smoothly so as to improve responsibility by forming ports at a piston boss in order to introduce negative pressure in a front and a rear work chamber or atmospheric pressure, and letting said ports be composed of a port in the axial direction and a port in the radial direction which are connected with each other via a bend surface. CONSTITUTION:The subject booster is provided with a control valve 32 interlocked with an input stem 35 inserted within a valve cylinder 25 which is connected with the rear end of a piston boss 10 connecting a front and a rear diaphragm 5 and 7 with each other. The piston boss 10 is formed with No.1 port 30 communicating the inside of a valve cylinder 25 with both negative pressure chambers 2a and 3a, and is formed with No.2 port 31 communicating the valve cylinder 25 with both working chambers 2b and 3b so that a control valve 32 allows No.2 port 31 to be communicated with No.1 port 30 or atmosphere while being switched over. In this case, No.2 port 31 is composed of a port 31A in the axial direction and a port 31R in the radial direction in such a way that these ports 31A and 31R are arranged at the same position in the circumferential direction of the boss 10 so as to be connected with each other via the bend surface (r) on the piston boss 10 smoothly continued to the inner surface of each port. |
