| 摘要 |
<p>A fluid pumping device having a pump housing containing a piston chamber and a reciprocating piston, an inlet port and an outlet port allowing a fluid to enter the piston chamber during an instroke of the piston and be expelled during an outstroke. The device further having a valve switching element movably mounted against a valve base member, with a piston chamber aperture connected to the piston chamber and an inlet aperture and an outlet aperture connected respectively to the inlet and outlet ports of the fluid pumping device. The element has a grooves in the valve base member providing, a first communication between the inlet aperture and the piston chamber aperture so that fluid is sucked, into the piston chamber during part of the piston instroke, and a second communication aperture expelling fluid out of the piston chamber, through the outlet port during part of the piston outstroke.</p> |
