NEGATIVE PRESSURE TYPE DOUBLER DEVICE

摘要

PURPOSE:To eliminate interference of a booster piston with a tie rod connecting the front and back walls of a shell by placing the booster piston in correct circumferential location with respect to the booster shell with a piston diaphragm interposed. CONSTITUTION:A locational projection 3c is formed at a ring-shaped bead 3a in the outside circumferential part of a piston diaphragm 3, and a locational hole 1c is excavated in the outside circumference of a thin conical member 1R formed behind the shell 1. The projection 3c is fitted in the hole 1c to have the circumferential location of the diaphragm 3 with respect to the shell 1. A notch 65 is cut in the back side wall 61a of a ring-shaped groove 61 formed in the booster piston 2, and a channel-shaped locational projection 64 is formed upright at the internal circumferential ring-shaped bead 3b of the diaphragm 3 as in a single solid body. The projection 64 is placed in engagement with the notch 65 to have the circumferential location of the piston 2 with respect to the diaphragm 3. Thereby the booster piston 2 is located in the circumferential direction with respect to the shell 1 through the diaphragm 3.