Claims
- 1. A pump comprising a pump cylinder, a piston within said cylinder, an entrance for fluid below said piston, an outlet above said piston, and means for raising and lowering said piston,
- said piston comprising a cylindrical body or organic polymer having a diameter such as to fit closely in said cylinder, said piston including a first check valve so constructed and arranged as to permit flow of fluid only upwardly through and relative to said body;
- said body comprising radially flexible flanges extending upwardly and downwardly from its periphery and extending completely about said periphery in close-fitting engagement with said cylinder;
- said first check valve comprising a substantially planar screen having numerous closely spaced small openings on the top of said body and a thin, flexible disc of organic polymeric material fixed on the upper surface of said planar screen and substantially covering the area bounded by said upwardly extending flange;
- said body being provided with a cavity immediately below and covered by said planar screen member and at least one passage extending from said cavity to the bottom of said body.
- 2. A pump as defined in claim 1 wherein the body of said piston is made of molded PTFE.
- 3. A pump as defined in claim 1 wherein said piston comprises two identical cups of organic polymer and means clamping said cups together with the flange of one cup extending upwardly and the flange of the other cup extending downwardly.
- 4. A pump as defined in claim 1 and further comprising a check valve assembly in said cylinder so constructed and arranged as to permit flow of fluid upwardly through said cylinder but prevent return flow;
- said check valve assembly comprising a cylindrical body of organic polymer having a diameter such as to fit closely in said cylinder, said body being fixedly but removeably mounted in said cylinder and having at least one passageway, extending through said block axially of said cylinder and a second check valve so constructed and arranged as to permit fluid flow only upwardly through said passageway;
- said second said check valve comprising a planar screen having numerous closely spaced small openings above said passageway and a thin, flexible disc of organic polymer having its central portion fixed on the upper surface of said horizontal screen member and substantially covering the upper surface of said body;
- said body being provided with a cavity immediately below and covered by said planar screen and communicating with said axially extending passageway.
- 5. A pump as defined in claim 4 wherein said piston comprises two identical cups of organic polymer and means clamping said cups together with the flange of one cup extending upwardly and the flange of the other cup extending downwardly and wherein said check valve assembly comprises a cup identical to one of the cups forming part of said piston.
- 6. A pump as defined in claim 4 wherein said valve assembly is positioned above said piston and further comprising a piston rod connected to said piston and extending through said check valve assembly and having a sliding fit with the body of said check valve assembly.
- 7. A pump as defined in claim 6 wherein the bodies of said piston and said check valve assembly are made of molded PTFE.
- 8. A pump as defined in claim 1 and comprising a flexible cord connected to said piston rod for raising said piston and means below said piston for lowering said piston when tension is released on said flexible cord.
- 9. A pump as defined in claim 8 wherein said means for lowering said piston is a weight.
- 10. A pump as defined in claim 8 wherein said means for lowering said piston is a spring.
- 11. A pump as defined in claim 10 wherein said valve assembly is fixed in said casing below said piston and said spring connects said piston and said valve assembly.
INTRODUCTION
This is a continuation-in-part of application Ser. No. 656,116, filed Sept. 24, 1984, now abandoned.
This invention relates to a well pump which is cheap to manufacture and long-lasting. It is so constructed that it avoids the necessity of the usual packing materials for the piston and inlet and/or outlet valves, and is capable of mass production at low cost.
There has been in the past few years considerable interest in the development of hand-operated water pumps for use in developing countries. Such pumps are, of course, also of value in remote areas of the United States and other industrialized countries where electric power is not readily available. It is also desirable that such pumps be capable of operation by power when it is available. Such pumps should be economical to manufacture on a large scale and be of such design that extensive upkeep is not necessary. Numerous pumps of this general character are described in a series of reports entitled "World Bank Technical Papers - Rural Water Supply and Pumps Project". The pump identified as the "Nepta Pump" is described in report #2 of that series, pages 32-36. This pump includes a flexible cord for pulling the piston up and a tension spring for pulling it down. The piston and valve structures illustrated are quite complicated and in the summary the pump was described as "expensive to buy".
Our invention is directed to a pump of the general type described above, but in which the piston and inlet and/or outlet valve assembly are made of plastic and the piston is so constructed that it does not require packing but is self-sealing with the pump cylinder.
US Referenced Citations (14)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 47802 |
Feb 1978 |
JPX |
| 938580 |
Oct 1963 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
| Parent |
656116 |
Sep 1984 |
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Patent Grant
4688999
