| 摘要 |
PURPOSE:To enhance the reliability of a piston in a spray pump having a piston by a method wherein the outer periphery and the inner wall of a valve housing is slided air-tight, and a lip piston having groove and a backup ring contacting the groove are installed. CONSTITUTION:A spray pump consists of a valve housing 4 having check valve 10, a center plug 5 to open and close air inlet hole 16, a plunger 6 having plural side holes 18, stem 7 having liquid passage 19, compression springs 11, 12 to energize the stem 7 and the piston, etc. In this pump, the outer periphery of the plunger 6 and the inner wall of the valve housing 4 are slided air tight. Also, a lip piston 9 having groove 20 along the circumference and a backup ring 8 which contacts the groove 20 in wedge shape are installed. To prevent excessive insertion of the ring 8, the piston 9 may have protrusion. The above structure completely prevents a gap which may occur between the sliding surface of the piston and mating wall surface, so that the reliability of the piston is enhanced. |
