Rod pumping well mouth back pressure reducing device

The utility model discloses a rod pumping well mouth back pressure reducing device which is installed at an oil well mouth. A high-pressure chamber and a low-pressure chamber are fixedly connected to form a closed chamber. A plunger with two side surfaces unequal in areas is arranged in the closed chamber and is formed by a plunger disc and a hollow plunger barrel perpendicularly and fixedly connected with the plunger disc. The surface area of the plunger on the side close to the well mouth is large and the surface area of the plunger on the side far away from the well mouth is small. A spring is arranged in the high-pressure chamber. One end of the spring is fixed on the plunger disc and the other end thereof is fixed on the inner side wall of the high-pressure chamber. A plunger check valve is arranged at the end of the hollow plunger barrel, a high-pressure check valve is arranged at the outlet of the high-pressure chamber and a low-pressure check valve is arranged at the inlet of the low-pressure chamber. Since the plunger with two side surfaces unequal in areas is used to be matched with the spring and the check valves, the goal of increasing the pressure of liquid at the oil well mouth is reached, no additional power is required for increasing the pressure and no additional pipeline is laid for releasing power fluid; and since the modularized connection is adopted, the structure is simple.