| 摘要 |
<p>A fluid pumping device comprising a pump housing (1; 101; 201; 301; 701; 901) containing a piston chamber (11; 101 '; 201 '; 310a, 301b; 701 '; 901 ' ) and a piston (2; 102; 202; 302, 302 '; 702; 902, 902 " ) moving back and forth inside the piston chamber, an inlet port (10i; 110i; 210i; 310i; 710i; 921) and an outlet port (10o; 110?; 210o; 310o; 710o; 920) allowing a fluid to be sucked into the piston chamber during an instroke of the piston and expelled from the piston chamber during an outstroke. The device further comprises a valve - switching element (9; 109; 201; 309; 701; 909 ) movably mounted against a valve base member (7; 107; 207; 307; 707; 907), which comprises a piston chamber aperture (12p; 112p; 212p; 312p, 312p 1; 712p; 912p) connected to the piston chamber and an inlet aperture (12i; 112i; 212i;312i;712i;912i) and an outlet aperture (12o; 112o; 212o; 312o; 712o; 912o) connected respectively to the inlet and outlet ports of the fluid pumping device. The element comprises a groove (14; 114; 214; 314, 314 '; 714; 914) or other recess (514) moving against the valve base member such that, a first communication allows leakage between the inlet aperture and the piston chamber aperture so that fluid is sucked from the inlet port, through the groove or recess, into the piston chamber during part of the piston instroke, while a second communication allows leakage between the piston chamber aperture and the outlet aperture expelling fluid out of the piston chamber, through the groove or recess and the outlet port during part of the piston outstroke.</p> |
