at least one piston chamber (1 101 201 310a, 301b 701 901 ) and the piston chamber at least one piston that reciprocates in the interior (2 102 202 302,302 702 902,902 ), the pump housing (1, including 101 201 301 701 901), the fluid to be drawn into the piston chamber during the stroke of the piston, and at least one inlet port to be discharged from the piston chamber during the out-stroke (10i 110i 210i 310i 710i 921) and at least one outlet port ( 10o 110 210o 310o 710o is described in relation to a fluid pumping device comprising 920). Fluid pumping apparatus includes a valve base member (7 107 207 307 707 907) is mounted to be movable against a valve switching element (9 109 201 309 701 909) and the further, the valve at least the base member is coupled to the piston chamber, a piston chamber opening (12p 112p 212p 312p, 312p 1 712p 912p), and the inlet and outlet ports, at least one inlet opening that is connected to the respective fluid pumping device ( 12i 112i 212i 312i 712i 912i) and at least one outlet opening (12o 112o 212o 312o includes 912o) 712o. The valve switching element comprises at least one groove (14 114 214 314,314 714 914) is arranged to move relative to the base member or the valve, including the other recess (514), said groove or recess is to form a first exchange to allow leakage between the inlet opening and the piston chamber opening, fluid is drawn into the piston chamber, at least over a groove or recess from a portion for the inlet port of the piston stroke, while the groove or recess to form a second exchange to allow leakage between the piston chamber opening and the outlet opening, the fluid is discharged from the piston chamber through a groove or recess the outlet port during at least part of the piston stroke out.적어도 하나의 피스톤 챔버(1 101 201 310a, 301b 701 901) 및 피스톤 챔버 내부에서 왕복 이동하는 적어도 하나의 피스톤(2 102 202 302, 302 702 902, 902)을 포함하는 펌프 하우징(1 101 201 301 701 901), 유체가 피스톤의 인스트로크 동안 피스톤 챔버로 흡입되게 하고 아웃스트로크 동안 피스톤 챔버로부터 배출되게 하는 적어도
