Piston chamber (11 101 201 310a 301b 701 901 ), and a piston that is configured to move back and forth in the piston chamber (2 102 202 302 302 702 902 902 ), the inlet port (10i exit port 921) (10o 110i 210i 310i 710i 110o 210o 310o 710o a 920), and the fluid between the in-stroke of the piston is sucked into the piston chamber, the pump housing having a, and inlet and outlet ports that are released from the piston chamber during the out-stroke fluid pumping apparatus including the (1 901 101 201 301 701). The apparatus further includes a valve member comprises a base (909 109 201 309 701 9), valve switching element which is mounted so as to be movable with respect to (7 907 107 207 307 707) a piston chamber opening which is connected to the piston chamber the member, and ( 112p 212p 312p 312p 712p 12p 912p), an inlet opening connected to the inlet and outlet ports of the fluid pumping device, each (12i I comprises a 912o) 112o 212o 312o 712o outlet opening (12o and 912i) 112i 212i 312i 712i. A groove that is configured to move relative to the valve base member the device is equipped recesses (or other 114 214 314 314 714 14 914) and (514), a piston chamber with inlet opening to create a communication path of a first cause leakage between the openings, from the inlet port, through the recess or groove during part of the in-stroke of the piston, to suction fluid into the piston chamber, a piston chamber opening Make a second communicating path that causes leakage between the outlet opening, the piston chamber, the fluid is discharged through the outlet port and the recess or groove during part of the out-stroke of the piston. [Selection Figure 8ピストンチャンバ(11;101’;201’;310a;301b;701;901’)と、ピストンチャンバ内で前後に動くように構成されたピストン(2;102;202;302;302’;702;902;902’)と、入口ポート(10i;110i;210i;310i;710i;921)と出口ポート(10o;110o;210o;310o;710o;920)であって、ピストンのインストロークの間は流体がピストンチャンバに吸引され、アウトストロークの間はピストンチャンバから放出される入口ポートと出口ポートと、を有するポンプハウジング(1;101;201;301;701;901)を具える流体ポンプ装置。この装置は、更に、バルブベース部材(7;107;20
