| 摘要 |
A valve for pumping a viscous fluid from a holding container includes a valve body having a fluid chamber, and a piston displaceable in the fluid chamber for pumping fluid from the fluid chamber through an outlet openings. The piston is attached to the end of a shaft which extends out of the valve. A hub with a plurality of openings and a resilient washer on its peripheral edge are slidably located on the shaft in the fluid chamber. When the piston is in contact with the hub it blocks the flow of fluid through the opening. When the hub is axially displaced from the piston, fluid is allowed to flow through the openings. Depression of the plunger causes movement of the piston away from the hub because of frontal engagement of the resilient washer with the walls of the fluid chamber. This allows the fluid to flow around the piston. Further movement of the shaft causes a projection on the shaft to engage the hub. The projection overcomes the frictional engagement and moves the hub along with, but displaced from, the piston through the chamber. The fluid contained in the chamber flows through the openings in the hub above the hub. Upon release of the plunger, a spring biases the piston upward to engage the hub and close its opening. During the movement of the piston and hub to their initial positions, under the spring bias, the fluid is pumped out of the outlet opening of the valve and substantially simultaneously enters into the lower portion of the valve chamber from the fluid-holding container.
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