| 摘要 |
<p>A small diameter fluid-driven pump for subterranean fluid sampling, and including an elongated cylindrical body formed by a centrally disposed control valve block assembly and a pair of hollow motor piston chambers on opposite sides of the valve block and joined thereto. Interconnected motor pistons are reciprocably disposed in the motor piston chambers, and each is connected to a pump piston. Each pump piston works within an axial bore in a tubular pump housing. The pump housings are secured to the opposite ends of the cylindrical body. A pump valve assembly is secured to the end of each pump housing, and each includes intake and discharge valves. Within the centrally disposed control valve block assembly in axial alignment with the motor pistons are a spool pilot valve and a spool fluid distribution valve. The spool pilot valve is constructed to obviate stalling during its reciprocation under the impress of a power fluid directed thereto, and it functions to control the shifting of the distribution valve to which it is internally connected within the valve block assembly. The distribution valve functions to alternately charge one motor piston chamber while receiving power fluid discharged from the other, then shifts, upon direction from the spool pilot valve, to charge the other motor piston chamber and receive exhausted power fluid from the one previously charged.</p> |
