| 摘要 |
A pumping apparatus is disclosed which uses a reversible, variable displacement hydraulic drive pump capable of pumping fluid under pressure. A hydraulic cylinder enclosing a piston is operatively connected to a port of the hydraulic drive pump. A fluid accumulator, which is precharged to a selected precharge pressure, is operatively connected to the other port of the hydraulic drive pump. The fluid accumulator supplies the fluid under the precharge pressure to the hydraulic drive pump. The hydraulic drive pump increases the pressure on the fluid to a working pressure required to drive the piston from a first position in a first direction to a second predetermined position. Upon reaching the second position, the hydraulic drive pump reverses direction to reverse the flow of fluid from the hydraulic cylinder thereby reciprocating the piston back to its first position, and directing the fluid to the fluid accumulator. Inertial forces on the piston surface area pressurize the reversed fluid to a first inertial pressure. The hydraulic drive pump increases the pressure on the fluid moving from the hydraulic cylinder toward the accumulator to a second pressure greater than the inertial pressure, and directs the fluid under the second pressure into the precharged fluid accumulator. Makeup or relief means in the apparatus maintain the second pressure equal to the selected charge pressure.
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