| 摘要 |
PURPOSE:To simplify seal structure by forming a series of bulged parts onto the annular inner peripheral bead of a piston diaphragm and strongly pressing said bulged parts in the direction of the center line and outwardly in the radial direction of the insertion hole of the diaphragm by the flange for preventing the slip- off of a valve cylinder and the tapered surface of the valve cylinder. CONSTITUTION:The inner peripheral bead 58 of a piston diaphragm 6 is fitted onto the opened edge of the insertion hole 41 of a booster piston 5, and said inner peripheral bead 58 has, in free state, a series of bulged parts 58a which project to the front-surface side 5a of the booster piston 5 and into the insertion hole 41, as shown by the chain line. When a flange 45 for preventing the slip- off of a valve cylinder 14 is locked between a locking plate 50 and the booster piston 5, said bulged part 58a is strongly pressed in the direction of the center line of the insertion hole 41 as shown by the arrow (b) by the slip-off preventing flange 45, and outwardly in the radial direction of the insertion hole 41 as shown by the arrow (c) by the tapered surface 46 of the valve cylinder 41, and compressed into the annular concaved part 62 on the periphery of the insertion hole 41. Thus, certain seal is secured between the valve cylinder 41 and the booster piston 5. |
