Pumps – Expansible chamber type – Valved piston
Patent
1996-03-15
1998-02-24
Freay, Charles G.
Pumps
Expansible chamber type
Valved piston
417554, 417260, 166 685, 166105, F04B 112, F04B 4702, F04B 4712
Patent
active
057206007
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to pumps lifting fluid from deep wells and, more particularly, the invention relates to sucker rod pumps.
PRIOR ART
Known in the art are plunger-type sucker rod pumps in which the plunger with a discharge valve moves in a hydraulic cylinder equipped with a suction valve, wherein the internal surface of the hydraulic cylinder features high hardness and is machined with a high accuracy. The plunger is also made with a high accuracy and has a reciprocating sealing device being a small clearance seal or an elastic sealing assembly made in the form of lip seals or piston rings (cf. A. B. Bezzubov, Yu. V. Schelkalin "Oil Lifting Pumps", Moscow, Nedra, 1986, p. 187, FIG. 81).
The prior art pumps have a precision pair "hydraulic cylinder--plunger", in which the length of the hydraulic cylinder can be 5 meters and more, while the plunger length is up to 2 meters, the plunger diameter and the inner diameter of the hydraulic cylinder varying in a range of 28 to 102 mm. These components are manufactured using complex machine tools and manufacturing process is very costly.
The wells having a significant gas content in the fluid being pumped require application of special devices which complicates the pump design and increases its price.
Also known in the art are plunger pumps comprising a housing with a cylindrical bore accommodating suction and discharge valves and a stationary sealing device. A smooth plunger is located in the cylindrical bore of the housing with a pap and reciprocates therein. The plunger is sealed by a stationary sealing device whose length is relatively small. The gap between the housing wall and the plunger is sufficiently large to avoid contact of the plunger with the housing. As a rule, such pumps are used in the surface equipment (cf. A. B. Bezzubov, Yu. V. Schelkalin "Oil Lifting Pumps", Moscow, Nedra, 1986, p. 194, FIG. 82).
In such pumps the plunger stroke is comparatively short. With a long stroke the pap between the housing and plunger much increases the so called "dead" space in the pump working chamber reducing the pump efficiency, particularly when the pumps are used in well with a high gas factor.
The use of a special valve in the sucker rod pumps makes it possible to reduce the adverse effect of the gas factor on the pump productivity. Known in the art is a sucker rod pump comprising a hydraulic cylinder with a suction valve, moving in the hydraulic cylinder a plunger having a discharge valve and forming a precision pair with the hydraulic cylinder, as well as a special valve in the pump upper portion, which is also made as a precision element to prevent gas looks in the pump (U.S. Pat. No. 4,219,311).
In such a pump the negative effect of the gas factor on the pump operation is reduced but at the expense of a special construction complicating the whole pump. In addition, there is also used an expensive and labor-consuming "hydraulic cylinder--plunger" precision pair.
SUMMARY OF THE INVENTION
The basic object of the invention is to provide a sucker rod pump that needs no a precision pair "hydraulic cylinder--plunger" while the elimination of the gas factor is made without using additional units in the pump system.
This object is attained by providing a sucker rod pump comprising a cylindrical housing with a suction valve, a stationary sealing device arranged on the cylindrical housing, and a hollow plunger with a discharge valve made with a possibility of reciprocating alone the cylindrical housing and interacting with the stationary sealing device; according to the invention, located in the cylindrical housing between the suction valve and the stationary sealing device is at least one additional sealing device spaced from the first sealing device and from one another, interacting with the hollow plunger whose length is equal to or larger than the sum of the distance between the adjacent sealing devices and the length of one sealing device but less than the sum of the double distance between the adjacent sealing devices and the length of
REFERENCES:
patent: 2684638 (1954-07-01), Sutton
patent: 2684639 (1954-07-01), Sutton
Freay Charles G.
Moon Samantha H.
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