OIL-WELL PUMP Russian patent published in 1995 - IPC

FIELD: oil industry. SUBSTANCE: pump has a cylinder with suction valve mounted at its bottom part. The valve is mounted inside a housing and has the seat and valving member. A hollow plunger with the delivery valve is positioned in the cylinder space. The cylinder consists of bushings interconnected through locking bushings. The inner diameter of the locking bushings is grater than the inner diameter of the bushings. The plunger is three-step. The diameter of the top step is grater than the diameter of the middle step and lesser than the diameter of the bottom step. Seals and sleeves are interposed alternatively between the faces of the top and bottom steps. The outer surface of the seals and sleeves are in contact with the surface of the cylinder bushings. The inner surface define a space together with the middle step of the plunger. A groove is provided on the outer surface of the seal. A spring ring is received in the groove for permitting contact with the cylinder bushing or locking bushing whose length is grater than the length of the outer surface of the sleeve. EFFECT: enhanced efficiency. 3 dwg