The invention discloses a double-pumping-prevention
oil pump. The double-pumping-prevention
oil pump comprises a pump
barrel, wherein the pump
barrel is connected with a working
barrel through an
upper joint; the pump barrel is connected with a bias fixed valve through a lower joint; a ring
valve seat is fixed on the working barrel; a sliding sleeve sleeves the outside of a slipping rod; a ring-shaped valve plug is fixed at the upper end of the sliding sleeve; and the ring-shaped valve plug is matched with the ring
valve seat. According to the double-pumping-prevention
oil pump, because the ring-shaped valve plug is used in the pump, the ring-shaped valve plug is closed in a downward
stroke,
liquid column high pressure exists above the valve plug, the inside of a pump cavity has low pressure, a rod string is stretched by
pressure difference, and the circumstance that eccentric wear of a rod tube is caused by bending of the rod string is avoided; and in down
stroke, down
pull force caused by difference of pressures of the upper end surface and the lower end surface of the slipping rod is increased, and thus, downward polished rod load is higher than downward polished rod load when aconventional pump is used. When in up
stroke, due to opening of the ring-shaped valve plug, the same
pressure system is arranged above a
plunger, under the condition that the pump
diameter is not changed, upward polished rod load is the same as that of the conventional pump, up load is not changed, down load is increased, action of a suspension point is relieved, and therefore, an energy-saving effect is achieved.