WO1986000962A1 - Water pump - Google Patents

Abstract

A pump, particularly intended for use in pumping water from bore holes in the developing countries, comprises a cylindrical casing (2), the interior of which is divided into first and second chambers (12, 14) by a tubular flexible membrane (16), and having inlet and outlet valves (8, 10) at either end thereof communicating with the interior of the first chamber (12). When the second chamber (14) is pressurised, the membrane (16) is deformed inwardly, the inlet valve (8) closes and the water contained in the first chamber (12) is forced out through the outlet valve (10). When the pressure is released, the outlet valve (10) closes and the inlet valve (8) opens and the first chamber (12) is refilled. The pump may be powered by hydraulic pressure using a manually operated piston or pneumatic pressure using a rotary compressor which is readily adaptable to a variety of energy sources.

Description

"Water Pump"

This invention relates to a pump intended particularly, but not exclusively, for pumping water from a bore hole or well. There is a particular need for simple, reliable and efficient water pumps in the developing countries where sources of drinking water are often scarce. Many water pumps presently in use for this purpose employ a piston situated underground, below the water level, which is operated by a pump handle at ground level. The piston is connected to the pump handle by steel connecting rods and a rigid rising main of steel or rigid plastics is employed.

It can take several skilled workmen two days to install a pump of this kind since rod and pipe sections must be assembled on site. To overcome the problem of weight and. corrosion in steel, plastics may be used. Further difficulties arise as rigid plastics pipe is prone to fracture. Whether steel or plastics are used, the weight and bulk of the materials creates transport difficulties, as bore holesare typically between 15 and 75m deep.

I= is an object of the present invention to obviate or mitigate these disadvantages and to provide a pump which is reliable, efficient, easily transported and simple to install.

There is already known a water pump which eliminates the need for connecting rods. This includes a casing defining a chamber having inlet and outlet valves and an expandable bladder positioned inside the chamber. The bladder is connected to a hydraulic pressure source so that, when the bladder is expanded, water in the chamber is forced through the outlet valve, This design mitigates some of the problems associated with traditional pumps but has been found to give an unsatisfactorily low flow rate.

According to the present invention, a pump comprises a substantially rigid casing which defines a closed volume, said volume being divided into first and second chambers by a flexible membrane, said first chamber being provided with an inlet and an outlet having valve means associated therewith, and said second chamber being connected to a pressure source.

Preferably, said casing is substantially cylindrical and said flexible membrane is tubular and positioned coaxially within said casing, the cylindrical volume within the membrane comprising said first chamber and the annular volume between the membrane and the casing comprising said second chamber.

Preferably also, said valve means comprises first and- second non-return valves. Preferably, the pressure source is connected to the pump by first piping means.

The pump may be operated by either hydraulic or pneumatic pressure.

When hydraulic pressure is employed, said pressure source is preferably a manually operated piston and the hydraulic fluid is preferably water.

When pneumatic pressure is employed, said pressure source is preferably a rotary compressor and the pump is preferably further provided with pressure relief valve means whereby the pressure in said second chamber may be released.

In the case of a pneumatically operated pump, said relief valve means is preferably ganged with second valve means whereby, when said pressure relief valve means operates to release the pressure in said second chamber, the pressure in said first piping means is maintained.

When the pump is used in a bore hole, the outlet of said first chamber is preferably connected to second piping means whereby water may be transported to the surface. Preferably also, said first and second piping means are comprised of flexible PVC pipe.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a sectional elevation of a hydraulically powered pump embodying the invention;

Fig. 2 is a section along line. II-II of Fig. 1, and Fig. 3 is a sectional elevation of a well head unit for use in conjunction with the pump of Fig. 1.

Fig. 4 is a sectional elevation of the upper part of a pump adapted to be powered by pneumatic pressure. Referring now to Figs. 1 and 2 of the drawings, a hydraulically powered pump comprises a substantially cylindrical casing 2, having an inlet port 4 and an outlet port 6, one at either longitudinal end thereof. A first non-return valve 8 is associated with inlet 4 and a second non-return valve 10 is associated with outlet 6. ^Tne interior volume of the casing 2 is divided into first and second chambers 12 and 14 by a tubular flexible membrane or diaphragm 16 which is positioned coaxially within the casing 2, extending the full length of the interior volume of the casing 2 and secured to the ends thereof by any suitable means, such as crimping. Thus, the first chamber 12 is essentially tubular, being defined by the interior volume of the membrane 16, and the second chamber 14 comprises the annular volume between membrane 16 and casing 2. The first chamber communicates with the inlet and outlet ports 4 and 6 via valves 8 and 10 while the second chamber 14 is connected to a hydraulic pressure source via port 18 and pipe 20. The outlet port 6 may be connected to a rising main 22. Operation of the pump is as followfe : initially, the first chamber 12 is primed with water and the second chamber 14 with hydraulic fluid (which may again be water). The inlet valve 8 is open at this time and the outlet valve 10 is closed. Hydraulic pressure is applied by any suitable means (one example being described below) via port 18, causing the tubular membrane 16 to be deformed inwardly. The increased pressure within the first chamber 12, caused by the inward deformation of the membrane 16, causes the inlet valve to close and the outlet valve to open and forces the water contained within the first chamber 12 out through the outlet port 6.

When the hydraulic pressure is released, the outlet valve 10 closes, the inlet valve 8 opens and the first chamber 12 is refilled via inlet port 4.

The pump may be positioned in a bore hole and used in conjunction with a manually operated well head unit. A suitable unit is shown in Figure 3.

The well-head unit comprises a casing 24 upon which a pump handle 26 is pivotably mounted at 28.

^•Movement of the handle 26 actuates a piston 30, slidably mounted in a cylinder 32, to create the hydraulic pressure required to operate the pump, cylinder 32 being connected to hydraulic drive pipe 20. The handle 26 is operably connected to the piston 30 by a piston rod 34, the rod 34 being pivotably connected to the handle 26 at 36. Additionally, the handle 26 is articulated at 38 so that lateral movement of the piston rod 34 caused by working of the handle 26 is minimised.

The unit also includes an outlet spout 40 which communicates with the rising main 22 via passage 42, and the .interior of the casing 24 is constructed so that some of the water from the passage 42 is allowed to spill back into the cylinder 32. This keeps the hydraulic system "topped up" and prevents the water contained therein from becoming stale.

Referring now to Fig. 4, a pump embodying the invention may also be powered by pneumatic pressure. As in the embodiment of Fig. 1, the pump comprises a substantially cylindrical casing 44 having its interior volume divided into first and second chambers 46 and 48 by a flexible membrane 50. In this case, air enters the second chamber 48 via an airline 52 and a channel 54 through the upper end of the casing 44. As the pressure in the second chamber 48 increases, the membrane 50 is deformed inwards, forcing the water therein out through the outlet channel 56 and into a rising main 57, via a non-return valve 58. As is shown, the pump is provided with a relief valve 60 which interconnects the exterior of the pump •and the interior of the second chamber 48 via a channel 62. Once a predetermined pressure is reached, the relief valve 60 opens and the pressure is released from the second chamber. The relief valve 60 then closes and the cycle begins again.

If the pump is being used in a relatively shallow bore hole, the relief valve 60 may be located_β:emote from the pump, e.g. at the surface, and connected therewith by piping. On the other hand, if the bore hole is deep, the relief valve is attached to, or ^"incorporated in, the pump and is preferably ganged with a shut-off valve 64 in the air line 52 or channel 54 so that when the relief valve 60 opens, the shut-off valve 64 closes so that the pressure in the airline is maintained, thereby reducing the cycle-time of the pump and increasing its delivery rate.

Fig. 4 shows the non-return valve 58 at the outlet of the pump located on the exterior of the casing 44. This simplifies construction of the pump as compared with the embodiment of Fig. 1 wherein the valves

8 and 10- are incorporated in the ends of the casing 2.

A rotary compressor (not shown) provides a suitable pneumatic pressure source for the pump. This is particularly advantageous for use. in the developing countries since it is readily adaptable to a number of energy sources: e.g. manually operated lever, pedal power, windmill as well as internal combustion engines or electric motors if available. In the case of both the hydraulic and pneumatic pumps there is no need for connecting rods extending from the well head to an underground piston, and accordingly the rising main and the hydraulic drive pipe may be constructed from flexible plastic piping (e.g. PVC or PVC reinforced with nylon mesh) . This is light and easily transported and also simplifies installation since the required length need only be cut* from a continuous piece of pipe. There is therefore no need for sections of pipe to be assembled on site and no special skills are required.

The pump casing may be made from plastics material such as ABS or from cast aluminium, the valve balls from ABS and the membrane from rubber or PVC. These materials conform to National Water Council standards, as does the PVC piping.

In a unit for use in a typical bore hole of 4 inches (102mm) diameter, the first chamber may have a volume of 40 fluid ounces so that each stroke delivers 2 pints of water. A pump of this size, together with 100 feet (33 metres) of piping and a well head unit or compressor weighs less than 30 lbs and may easily be carried in the boot of a standard car.

The pump is maintenance free and, in the case of the hydraulic, pump, the only maintenance required for the well head unit would be the periodic replacement of a washer, requiring the minimum of skill.

Claims

1. A pump comprising a rigid casing defining a closed volume, said volume being divided into first and second chambers by a flexible membrane, said first chamber having an inlet and an outlet having valve means associated therewith, and said second chamber being connected to a pressure source.

2. A pump as claimed in claim 1, wherein said casing is substantially cylindrical and said flexible membrane is tubular and positioned co-axially within said casing, the cylindrical volume within the membrane comprising said first chamber and the annular volume between the membrane and the casing comprising said second chamber.

3. A pump as claimed in claim 1 or 2, wherein said valve means comprises first and second non-return valves.

4. A pump as claimed in any preceding claim wherein said pressure source is connected to the pump by first piping means.

5. A pump as claimed in any preceding claim wherein said pressure source is a hydraulic pressure source.

6. A pump as claimed in claim 5 wherein said hydraulic pressure source comprises a manually operated piston. *

7. A pump as claimed in claim 5 or 6 wherein the hydraulic fluid is water.

8. A pump as claimed in any of claims 1 to 4 wherein said pressure source is a pneumatic pressure source.

9. A pump as claimed in claim 8 wherein said pneumatic pressure source is a rotary compressor and said pump is further provided with pressure relief valve means whereby the pressure in said second chamber may be released.

10. A pump as claimed in claim 4 and claim 9 wherein said pressure relief valve means is ganged with second valve means whereby, when said pressure relief valve means operates to release the pressure in said second chamber, the pressure in said first piping means is maintained.

11. A pump as claimed in any preceding claim wherein the outlet of the pump is connected to second piping means.

12. A pump as claimed in claim 4 and claim 11 wherein said first and second piping means are comprised of flexible PVC pipe.