| 摘要 |
Disclosed is a hydraulic oil well pumping method and apparatus. The apparatus includes: a) a hydraulic cylinder having a rod that is movable between a upper and lower rod positions; b) a pumping string that extends downwardly from the rod, the string being configured to extend into an oil well for pumping oil from the well; c) a prime mover; d) a hydraulic pump that is powered by the prime mover, the pump having a compensator that regulates pump flow and pump pressure; e) a directional control valve that moves between open flow and closed flow positions; f) a first flow line connecting the pump and the hydraulic cylinder, the directional control valve being positioned in the first flow line so that it can control flow between the hydraulic pump and hydraulic cylinder; g) a proportioning valve; h) a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump; i) a second flow line that transmits hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve; j) an electronic control system that controls movement of the rod as it moves between the upper and lower rod positions by controlling the directional control valve and the proportioning valve, wherein the control system includes an electrical signal that enables a selective opening, choking, or closing of the proportioning valve so that a control of rod movement is enabled when the rod is to be elevated, lowered or rod direction is to be changed, k) wherein the proportioning valve is choked to lower the rate of flow of hydraulic fluid in the flow line from the hydraulic cylinder to the reservoir after the rod has descended a partial distance between the upper rod position and the lower rod position, the partial distance being a majority of the distance between the upper and lower rod positions; I) the control system lowering the rod at a first higher speed before the proportioning valve is choked and wherein the rod travels the majority of the distance between the upper and lower position and then lowering the rod at a second lower speed after the proportioning valve is choked; m) wherein the electronic control system includes a plurality of three proximity switches and when the rod assumes a selected position relative to each proximity switch, the control system activates each proximity switch. |
