Energy saving closed loop hydraulic oil pumping unit

The utility model discloses an energy saving hydraulic pumping unit with closed-loop. The frequency conversion technique is applied to control the rotational speed of an electric motor, the output flow-rate of a control pump and moreover the running speed of the pumping unit, the pumping unit, a pumping rod and a pumping pump being dynamically coordinated with significant production-increasing and energy-saving. According to the system requirement, the speed regulation of the frequency conversion can provide the flow to decrease the loss of overflow, the output power being adapted to the load requirement without reference of load change, and strong self-controlling performance being provided. With an upper and a lower travel switch, a speed and a displacement sensor, etc, through a controller and a frequency converter, the technique of the vector closed-loop control of an electric motor and an electromagnet of control valve is accomplished, and the protecting functions for excess load, excess current, excess voltage and instantaneous stall are achieved. With the utility model, basing on that the integral efficiency of the pumping unit is increased, the efficiency of the hydraulic pump and the electric motor is increased to the most extent, as well as the installation power of the pumping unit is decreased to make the descending energy of the pumping unit to be effectively used. The pumping unit can be widely used for oil production of oil field.