| 摘要 |
<p>An apparatus (50) for pumping a fluid from a fluid reservoir (30), the apparatus (50) comprising a piston (13, 14) adapted for reciprocating upwardly and downwardly for pumping the fluid. The apparatus (50) further comprises a first annular fluid chamber (32) partially delimited by the piston (13, 14), a second annular fluid chamber (34) laterally surrounding the first fluid chamber (32), and a fluid communication recess (6) adapted for providing a fluid communication between the first fluid chamber (32) and the second fluid chamber (34). A movable valve (5, 15, 19) is provided which is adapted so that when the flow of fluid originating from the fluid reservoir (30) to the first annular fluid chamber (32) is disabled by the movable valve (5, 15, 19), the piston (13, 14) moves upwardly and fluid flows from the second fluid chamber (34) into the first fluid chamber (32), and when the flow of fluid originating from the fluid reservoir (30) to the first annular fluid chamber (32) is enabled by the movable valve (5, 15, 19), the piston (13, 14) moves downwardly and fluid flows from the first fluid chamber (32) into the second fluid chamber (34).</p> |
