| 摘要 |
In order to drive a rod pump, especially a petroleum lifting pump, a secondary power-control drive system is provided according to the invention, which comprises at least one hydrostatic machine working as a motor or as a pump for driving the pump cylinder and a further hydrostatic machine, which is linked to the first machine and which has an adjustable absorbing volume or output volume and is connected to a hydraulic accumulator and a driven pump. By means of setting the angle of traverse of the adjustable machine, the lifting and lowering movement of the pump is effected, pressure medium being withdrawn, for the purpose of lifting, from the accumulator in addition to the pressure medium quantity supplied by the driven pump, while during lowering, pressure medium is conveyed into the accumulator. Thus provision is made for recovering pump drive energy. As the driven pump runs continuously, conveying pressure medium into the adjustable machine during lifting and conveying pressure medium into the accumulator during lowering, the power input is reduced considerably.
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