AP594A

AP594A - Fluid pump.

Info

Publication number: AP594A
Application number: APAP/P/1995/000764A
Authority: AP
Inventors: Brian Du Plessis Barry
Original assignee: Pumpwell Pty Limited
Priority date: 1994-09-09
Filing date: 1995-09-08
Publication date: 1997-09-09
Also published as: AP9500764A0; ZA957564B

Abstract

A pump for water or other liquid comprises a housing which has an inlet and an outlet with respective non-return valves.

Description

A BACKGROUND OF THE INVENTION

This invention relates to a liquid pump, and also to a method of operating the pump.

Conventional borehole pump systems typically have a robust metal construction, which results in the various components of the pump system being heavy and difficult to install in a borehole. Furthermore, such borehole pump systems are not easily transportable, and also tend to be expensive.

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SUMMARY OF THE INVENTION

According to the invention there is provided a liquid pump comprising :

a housing defining a pump chamber;

< a pump piston capable of reciprocating movement within the pump chamber between a first position and a second position on a discharge stroke, and between the second position and the first position on an intake stroke;

a non-return intake valve arranged to allow the intake of liquid into the chamber from a liquid reservoir during the intake stroke;

a non-return delivery valve arranged to allow the discharge of liquid from the chamber during the discharge stroke; and o .

a spring arranged to act against the movement of the piston on the . discharge stroke, and to at least assist the movement of the piston on the intake stroke.

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In a preferred embodiment, the pump includes hydraulic actuating means which act on the pump piston to effect at least the discharge stroke of the pump piston.

The hydraulic actuating means preferably includes a drive cylinder, a drive piston capable of reciprocating movement in the drive cylinder, and a conduit in hydraulic communication with the pump piston, so that a force * M

00594 applied to the drive piston is communicated via liquid in the conduit to the pump piston within the pump chamber.

The conduit is preferably an'elongate, flexible tube or pipe.

The pipe may be formed from a plastics material.

The pump piston may be reciprocable within a cylinder defined within the pump chamber.

The spring may be a helical coil spring, and may be seated within the cylinder and arranged to return the pump piston to a rest position after a discharge stroke.

Preferably, the force exerted by the spring on the pump piston is substantially sufficient to effect the intake stroke thereof.

The pump may include a delivery conduit which is in liquid communication with the pump chamber via the delivery valve.

The delivery conduit is preferably an elongate, flexible tube or pipe.

The delivery pipe preferably is formed from plastics material.

The drive piston may be actuated by a hand-operated lever, a motor or a windmill, for example.

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- 4 BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic side view of a pump according to the invention with the pump piston thereof in a rest position;

Figure 2 is a similar view of the pump system of Figure 1 with the pump piston performing a discharge stroke; and

Figure 3 is an exploded side view of an embodiment of the pump.

DETAILED DESCRIPTION OF AN EMBODIMENT

Referring to Figure 1, there is shown a pump 10 submerged in an underground water reservoir 12. The pump 10 comprises a housing 14 defining a cylinder 16, an intake portion 18 and a delivery conduit 20. The cylinder 16, intake portion 18 and delivery conduit 20 define an internal pump chamber 22. At the lower end of the intake portion 18, there is provided a non-return intake valve 24, through which water from the water reservoir 12 is drawn into the pump chamber 22. At the upper end of the delivery conduit 20 there is a non-return delivery valve 26 through which water is discharged from the pump chamber 22.

Housed in the cylinder 16 is a piston 28, which is capable of reciprocating movement within the cylinder 16. Also seated in the cylinder 16 is a compression spring 30, which is retained between the piston 28 and a shoulder 32 defined by the cylinder 16. The spring 30 is a helical coil spring, typically formed from a carbon steel which is hard-drawn. To

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AP. 00594 provide the spring with a high degree of corrosion resistance, stainless steel or a non-ferrous alloy could also be used to construct the spring 30. It will of course be appreciated that any other suitable form of spring, such as a gas spring, could be used to act oh the piston 28, the purpose of the spring being simply to return the piston into its fully retracted or rest position, as shown in Figure 1, in use.

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The housing 14 is fabricated from a moulded thermoplastics material, such as polyvinyl chloride (PVC). The housing 14 may either be moulded as an integral unit, or may be assembled from a number of moulded components which are connected together by suitable couplings.

Above ground level, there is a drive piston 34 housed in a cylinder 36, and actuated by a drive rod 38. The drive rod 38 may in turn be actuated by a hand-operated lever or another manually operated mechanism, a petrol, diesel or electric motor or a windmill, for example. Connected between the — cylinders 16 and 36, and extending the length of the borehole 40, is a first

Θ pipe 42 which is typically a class 10 polyvinyl chloride (PVC) or a high density polyethylene (HDPE) pipe having a diameter of between 32 and 40 millimeters, and a length of between 20 and 100m (depending of course on the depth of the borehole 40).

A second delivery pipe 44 is connected to the upper end of the delivery conduit 20 of the housing 14, the delivery pipe 44 also extending the length of the borehole, so that a free end 46 thereof protrudes above the ground 48. The delivery pipe 44 is typically constructed from a class 6 polyvinyl chloride (PVC) or an HDPE pipe, and has a diameter of between 32 and 40 millimeters.

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The connections between the housing 14 of the pump 10 and the pipes 42 and 44, as well as the connection between the cylinder 36 and the pipe 42, are typically spigot-and-socket type connections, which may be reinforced by fastening collets (not shown) around the ends of the pipes 42 and 44.

Shown in ghost outline and connected between the pipes 42 and 44, is an r optional non-return valve 45, which allows the flow of water from the delivery pipe 44 to the pipe 42. It is envisaged that water contained in the delivery pipe 44 could be used to continually prime the pipe 42, from which water leakages may occur in use. Thus, when the pressure in the pipe 42 drops to below atmospheric pressure due to leakages, the pipe 42 can be refilled with water from the delivery pipe 44 via the non-return valve 45.

The installation and functioning of the pump 10 will now be described with reference to Figures 1 and 2. As a first step in the installation procedure of the pump 10 in a borehole 40, the pump housing 14 is connected to the pipes 42 and 44, and the drive cylinder 36, at an above ground location. As the entire pump assembly is constructed from a lightweight plastics material, the pump can then easily be transported to a borehole 40 into which it is to be installed. At the borehole location, the pump 10 is installed into the borehole 40 by inserting the housing 14 into the mouth of the borehole 40, followed by the pipes 42 and 44, and then lowering the housing 14 until at least the intake valve 24 is submerged in the underground water reservoir 12. To optimise the functioning of the pump 10, it is preferable to submerge the entire housing 14 in the reservoir 12, as is shown in Figure 1.

As a next step in the installation procedure, the pipe 42 and cylinder 36 are primed with water 50, before the piston 34 and the drive rod 38 are installed

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- 7 t i »i fl /, V V J d within the cylinder 36. It will be appreciated that the pipe 42 and cylinder 36 could be primed with any fluid substance which is capable of being poured into the pipe 42, and which will be capable of transmitting a force from the drive piston 34 to the piston 28 housed in the cylinder 16. The drive rod 38 is then connected to a suitable actuating means, which may be a hand-operated lever mechanism, a motor, or a windmill, as discussed above.

The lightweight and flexible nature of the pump components allow the pump to be installed easily and quickly into a borehole 40. In trials conducted by the inventor, the pump 10 was dropped into a 40 meter borehole in a time of approximately one and a half minutes by an installation team comprising two persons. Furthermore, the entire operation of dropping the pump 10 into the borehole, and priming the pipe 42 and the cylinder 36 required merely between 15 and 20 minutes.

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Once the pump 10 is installed as shown in Figure 1, the drive rod 38 is driven in a direction indicated by the arrow A in Figure 2 to begin die pumping action. As the drive piston 34 moves down through the cylinder. 36, the water 50 in the cylinder 36 and the pipe 42 is forced downwardly, thereby exerting a force on the piston 28, which in turn exerts a compressive force on the spring 30. As the piston 28 moves downwardly in the cylinder 16, the water contained in the pump chamber 22 will be pressurised, thus causing the intake valve 24 to close, and the delivery valve 26 to open.

As the piston 28 continues on its downward motion, the water in the chamber 22 will be forced through the delivery valve 26 into the delivery pipe 44. When the piston 28 reaches the end of its downstroke, the

AP.00594 actuation force is removed from the drive rod 38, whereafter the piston 28 is now biased by the spring 30 towards the rest position shown in Figure 1, and the piston 28 thus begins its upstroke.

As the piston 28 begins the upstroke, the pressure in the chamber 22 will drop, thus causing the delivery valve 26 to close, and the intake valve 24 to open. As the piston 28 continues on its upstroke, water from the reservoir 12 will be drawn into the chamber 22 until the piston 28 reaches the end of its upstroke. As the delivery valve 26 is closed during the upstroke of the piston 28, the column of water contained in the delivery tube 44 is prevented from returning to the pump chamber 22.

The characteristics of the spring 30 are carefully selected, so that it is sufficiently strong to execute the upstroke (intake stroke) of the piston 28 at the intended operating depth of the pump.

By the repetitive application of a drive force to the drive rod 38, the pumping action as described above will result in the filling of the delivery pipe 44 with water from the reservoir 12. Once the delivery pipe 44 has been filled the continued application of the periodic force to the drive shaft 38 will then result in water being discharged from the free end 46 of the delivery pipe 44. In experiments conducted by the inventor using the above described embodiment, a flow rate of between 1 800 and 2 000 litres per hour was achieved when pumping water from a depth of approximately 35 meters.

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The inventor believes that the pumping action of the pump 10 may be assisted in that the column of water 50 contained in the pipe 42, between the

- 9 pistons 34 and 28, may have a natural resonance, which is determined by the weight of the column, and the flexibility and elasticity of the spring 30. By applying a periodic force to the drive shaft 38 having a frequency approximately equal to the natural frequency of the column of water 50, the column of water 50 may be made to resonate within the pipe 42, and the inventor speculates that this may enhance the pumping action. However, it should be understood the above stated proposition is merely speculation, and it is in no way alleged that the invention does in fact function in this way, or that this functioning provides any result or advantage.

As will further be appreciated, water dispensed from the pump as described above will have an intermittent flow. However, it is envisaged that by fitting a suitable regulating device to the pump 10, a steady and continuous flow of water will be achieved.

Figure 3 is an exploded view of an actual embodiment of the pump of the invention. In Figure 3, equivalent parts are given the same numbering, where possible, as in Figures 1 and 2.

This embodiment of the pump is intended for manual use, and comprises a base plate 52 which will typically be mounted on a concrete base and which supports a cylindrical casing 54 to which is fixed a bracket 56. The bracket defines a fulcrum 58 to which a connector rod 60 is pivotably connected at one end thereof, and at the other end thereof to one end of an operating lever 62. Via a rod 64, the lever 62 bears on the drive piston 34, which is fitted with a pair of O-rings and which reciprocates in the cylinder 36. The cylinder 36 is connected via the pipe 42 and associated connectors to the cylinder 16, in which the piston 28 is reciprocable against the urging of the

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AP .00594

- 10 spring 30.

The housing 14 which defines the pump chamber 22 comprises a 45° T piece, while the delivery conduit 24 comprises a 45° elbow. The other components of the pump are conventional connectors and plumbing components, of the kind which are readily available in the market place, r This means that relatively few specialised parts are required to manufacture the pump.

The above described pump 10 provides a number of advantages which makes the pump particularly useful for pumping water from boreholes in rural and low-income areas. Firstly, the components from which the pump 10 is constituted are relatively inexpensive. Secondly, the components of the pump 10 are lightweight, thus allowing the pump 10 to be transported easily to a borehole location. For example, the pump could be carried by foot from a distribution point to remote rural locations where water shortages are

J · being experienced. A third advantage is that the pump 10 is easily and φ quickly installed into a borehole and the installation procedure requires no special installation equipment such as a block and tackle. Fourthly, the flexibility of the pipes 42 and 44 allows the pump to be installed into a borehole where the shaft of the borehole is not regular and follows a curved path. Finally, the fact that the mechanism for driving a pump, such as a motor or a windmill, is situated above ground facilitates the easy maintenance and repair of the relevant drive mechanism.

Claims

1. A liquid pump comprising:

a housing defining a pump chamber;

a pump piston capable of reciprocating movement within a cylinder defined within the pump chamber, between a first position and a second position on a discharge stroke, and between the second position and the first position on an intake stroke;

a non-return delivery valve arranged to allow the discharge of liquid from the chamber during the discharge stroke;

a spring seated within the cylinder and arranged to act against the movement of the piston on the discharge stroke, and to at least assist the movement of the piston on the intake stroke.

2. A liquid pump according to claim 1 which includes hydraulic actuating means which act on the pump piston to effect at least the discharge stroke of the pump piston.

3. A liquid pump according to claim 2 wherein the hydraulic actuating means includes a drive cylinder, a drive piston capable of reciprocating movement in the drive cylinder, and a conduit in hydraulic communication with the pump piston, so that a force applied to the drive piston is communicated via liquid in the conduit to the pump piston within the pump chamber.

4. A liquid pump according to claim 3 wherein the conduit is an elongate, flexible tube or pipe.

5. A liquid pump according to claim 4 wherein the conduit is formed from a plastics material.

6. A liquid pump according to claim 5 wherein the plastics material is polyvinyl chloride or high density polyethylene.

7. A liquid pump according to claim 6 wherein the spring is a helical coil spring seated within the cylinder and arranged to return the pump piston to a rest position after a discharge stroke.

8. A liquid pump according to claim 7 wherein force exerted by the spring on the pump piston is substantially sufficient to effect the intake stroke thereof.

9. A liquid pump according to any one of claims 1 to 8 including a delivery conduit which is in liquid communication with the pump chamber via the delivery valve.

10. A liquid pump according to claim 9 wherein the conduit is an elongate, flexible tube or pipe.

11. A liquid pump according to claim 10 wherein the conduit is formed from a plastics material.

12. A liquid pump according to claim 11 wherein the plastics material is polyvinyl chloride or high density polyethylene.

13. A liquid pump according to any one of claims 2 to 12 wherein the hydraulic actuating means is arranged to be driven by a hand-operated lever, a motor or a windmill.

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ABSTRACT

A pump for water or other liquid comprises a housing which has an inlet and an outlet with respective non-return valves. A pump piston is arranged to reciprocate in a cylinder which is in communication with the pump chamber. A spring biases the piston into a rest position. A hydraulic actuator is

Γ' connected to the cylinder by a flexible pipe, so that operation of the actuator moves the pump piston on a discharge stroke, against the spring, forcing liquid out of the outlet. When the pump piston is released, it returns to its rest position under the urging of the spring, performing an inlet stroke which draws liquid in through the inlet. The pump may be located in a borehole, with the hydraulic actuator at the top of the borehole.