| 摘要 |
A hydraulic rod pumping unit (12) has a constant horsepower regenerative assist featuring downstroke energy recovery. The pumping unit (12) has a hydraulic ram (26) connected to a ram pump (18). The drive shaft (40) of the ram pump (18) is coupled to the drive shaft (38) of an accumulator pump (20) and to a rotor of a drive motor (16). A hydraulic accumulator (24) is connected to the output of the accumulator pump (20). The ram pump (18) and the accumulator pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the accumulator pump (20) and during the up stroke of the hydraulic ram (26) the accumulator pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).
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