CA1260317A

CA1260317A - Well pump

Info

Publication number: CA1260317A
Application number: CA000491106A
Authority: CA
Inventors: Kenneth R. Ames; James M. Doesburg
Original assignee: Battelle Development Corp
Current assignee: Battelle Development Corp
Priority date: 1984-09-24
Filing date: 1985-09-19
Publication date: 1989-09-26
Also published as: AU6838087A; AU599077B2; EP0294373A1; WO1988004365A1

Abstract

ABSTRACT

A well pump includes a piston and an outlet valve assembly of special structure. Each is formed of a block of organic polymer, preferably PTFE. Each includes a cavity in its upper portion and passages leading from the cavity to the bottom of the block. A screen covers each cavity and a valve disk covers each screen. Flexible sealing flanges extend upwardly and downwardly from the periphery of the piston block.
The valve block has a sliding and sealing fit with the piston rod.

Description

3~7 1 IN ~OD~CTION
. _

2 This invention relates to a well pump wh ch is cheap ~c

3 manufacture and long-lasLing. It is so constructed that it

4 avoids t~e necessity cf the usual packing materials for the piston and outlet valves, and is capable of mass production 6 at low cost.

8 There has been in the past few years consiaerable interest 9 in the development of hand-operated water pumps for use in developing countries. Such pumps are, of course, also of value 11 in remote areas of the United States and other industrialized 12 countries where electric power is not readily available. It is 13 also desirable that such pumps be capable of operation by power 14 when it is available. Such pumps should be economical to manu-facture on a large scale and be of such design that extensive 16 upkeep is not necessary. Numerous pumps of this general character 17 are described in a series of reports entitled "World Bank Tech-18 nical Papers - Rural Water Supply and Pumps Project". The pump 19 identified as the "Nepta Pump" is described in report ~2 of that series, pages 32-36. This pump includes a flexible cord 21 for pulling the piston up and a tension spring for pulling it 22 down. The piston and valve structures illustrated are quite 23 complicated and in the summary the pump was described as 24 "expensive to buy".

SUM~I~RY OF THE INVENTION
26 Our invention is directed to a pump of the general type 27 described abo~-e, but in which the piston and outlet valve 28 assembly are made of plastic and the piston is so constructed 29 that it does not require packing but is self-sealing with the pump cylinder.

3~l~
26494-9~
In accordance with the present invention, there i5 provided a pump comprising a pump cylinder, a piston wlthin said cylinder, an entrance for fluid below 3aid pi~ton, an outlet above said piston, and means for raising and lowering said plston, said piston comprising a cylindrical body of organic polymer having a diameter such as to fit closely in ~aid cylinder, said piston including a first check v~lve so construc~ed and arranged as to permit ilow of fluid only upwardly through and relative to said body; said body comprising radially flexible flanges ex~ending upwardly and downwardly from its periphery and extending comple~ely abou~
said periphery in close-fltting engagement ~th said cylinder;
said first check valve compri~ing a substantlally planar screen having numerous closely spaced small openings on the top of said body and a thin, flexible disc of organlc polymeric material fixed on the upper surface of said planar screen and substantially covering the area bonded 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 sald body, said pump further comprislng a second check valve connected to said cyllnder in such a manner as to permit ~low upwardly through said cylinder and prevent flow downwardly therethrough.

la 1 BRIE? DESCRT?TI~ F T~E ~ JG~

2 In the drawinss Fi~ure 1 is a vertical section of one 3 embodiment of our pump. Figure 2 is a vertical sect-on of a 4 second embodiment of our pump~
DETAILED DESCRIPTIO~J
6 Referring to Fiaure 1 the pump includes a cylinder 2.
7 The upper portion of which is imperforate and.pre.erably made 8 of stainless steel. The lower portion of the cylinder wall 4 ~ is in the form of a screen. This screen is preferably made u?
of a plurality of cir_umferential, trapezoidal bars which have 11 their widest portions on the outside. On the interior of these 12 bars are vertical bars, also of trape20idal shape. The cir-13 cumferential bars are closely spaced to form a slotted screen.
14 The vertical bars serve as supports. This is a screen which has a very low resistance to water flow. It is co.m~erciallv 16 available both in metallic form and made of plastic.
17 Within the cylinder 2 is a piston 5, including a piston body 18 6 which is preferably made of injection-molded polytetrafluoro-19 ethylene (PTFE). The material is sold under the trademar~
"Teflon". It is long-lasting and has excellent anti-friction 2i characteristics. The piston includes flanges 8, 10 which extena 22 upwardly and downwardly from the body 6. The pis~on body includes 23 a cavity 12 and a number of flow channels 14. Seated in the 24 upper portion of the piston body above cavity 12 is a screen 16. This screen is made up of horizontal bars, trapezoidal in 26 shape with their wider portions uppermost. They are closely 27 spaced to provide a screen which, however, has little resistance 28 to water flow. These bars are supported from beneath bv 29 relative~y widely spaced bars at right angles to them and joined to them. On top of the screen is a valve disk 18, also made of 31 PTF~. In t`-.e embodiment shown, it is fle~ible and clamped to 32 piston rod 20 by lockwasher 22. However, it may be rigid and 3~77 1 sl~ .lle oro~ 20 a s.op ~eing prGvlded on rod 25 ~o li- -2 its t . ~
3 ~~n the upper portion of cylinder 2 is ar outlet valve 4 asserbly indicated generally as 24. It includes a valve blcc--.
26 ~hich is o_ the same general construction as piston boay 6.
6 However the flanges 8 and 10 are not required. Valve block 7 26 is held in cylinder 2 by screws 28 which are backed out into 8 threaded holes in the cylinder 2. It is sealed in the cylinder g by O~ring 30. At the top of valve block 26 are screen 32 znd L0 valve disk 34 which are of the same structure as screen 15 ard 11 valve disk 18, respectively. Valve disk 34 in the embodiment 12 shown is held in place by hollow bolt 36 which is threaded 13 into valve block 26. The upper end of stainless steel piston 14 rod 20 is connected to a flexible cord 38 which extends upwarcly through discharge pipe 40. The upper end of cord 38 is con-16 nected to any suitable hand or powered mechanism which will 17 periodically apply tension to it. In this modification, the 18 lower end of piston rod 20 is connected to a tension spring 42 19 which in turn is connected to a rigid member 44 at the bottom of cylinder 2.
21 In ~igure 2 the structure is identical to that of Figure 1, 22 except that the spring 42 is replaced by a weight 50.
23 This is a bucket valve force pump and it is preferably mounted 24 below the level of the ground water. Assuming the piston 6 is in its highest position, tension is released on cord 38. This piston 26 is either drawn down by spring 42 (Figure l) or caused to descend 27 by weight 50, Figure 2. Flange 10 which is flexible is 28 forced against the wall of screen 4 or cylinder 2 and forms a seal.
29 Wa-er is forced through channèls 14 cavity 12 and screen 16 raising valve disk 18 and allowing water to accumulate above the 31 piston. Tension is then applied to cord 38. Piston 6 is drawn 32 upwardly forcing flanges 8 against the cylinder wall and forming a 3~

1 seal. This rurc~ upward~ thrcugh the ~alve asse~.~ly 2~
2 raising val~7e disk 3~ ~nG orcir~ the ~Jater u?wardl~ through ?ipe 3 40. When tension is again re eased, the pres,ure ~orces val--Je 4 disk 34 agairist khe -top of screer. 32 forming a seai and prevent-ing backflow.
6 A valve assembly of the same general structure as assembly 7 24 may be used below piston 5 instead of, or in addition to, 8 assembly 24.
9 The PTFE of which valve block 26 is made has excellent anti-L0 friction properties in contact with metal. The piston rod 20 is 11 made originally with an interference fit and quickly works itself 12 into a low-friction sealins relationship. The flanges 8 and 10 c 13 the piston are flexible and act as sealing means so that the pis-14 ton does not require packing. The PT~E, while relatively expensive as a material, can be readily formed by injection molding so that 16 the parts can be mass produced at a low expense. The absence c_ 17 packing which needs periodic renewing makes for long life. ~his 18 design, thererore, provides a low cos~, nighly effective pump.
19 While PTFE is particularly desirable for use in the piston an'; valve assembly, other moldable polymers havin~ good stability 21 and low coefficients of friction in contact with metals may be 22 substituted. Examples are polyethylene, nylon, and Viton 23 (copolymer of vinylidene fluoride and hexafluoro propylene).
24 Instead of stainless steel, the metallic members may be made of corrosion-resistant metals, e.g., nickel, or sim?le ~6 alloys, such zs bronze.
27 While we have described certain embodiments of our inven-28 tion in detail, it will be apparent that various other ehanges 29 can be made. We therefore wish our patent coverage ~o be limited solely by the sco~e of the appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

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 of 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 bonded 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, said pump further comprising a second check valve connected to said cylinder in such a manner as to permit flow upwardly through said cylinder and prevent flow downwardly therethrough.

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 second check valve forms part of a check valve assembly in said cylinder, 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, said second check valve so constructed and arranged as to permit fluid flow only upwardly through said passageway;
said second 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.

4. A pump as defined in claim 3 wherein said check 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.

5. A pump as defined in claim 4 wherein the bodies of said piston and said check valve assembly are made of molded PTFE.

6. A pump as defined in claim 4 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.

7. A pump as defined in claim 6 wherein said means for lowering said piston is a weight.

8. A pump as defined in claim 6 wherein said means for lowering said piston is a spring.