WO2013190287A1

WO2013190287A1 - Pump

Info

Publication number: WO2013190287A1
Application number: PCT/GB2013/051588
Authority: WO
Inventors: David Hutton
Original assignee: Hutton Technologies Ltd
Priority date: 2012-06-19
Filing date: 2013-06-19
Publication date: 2013-12-27
Also published as: AP2015008195A0

Abstract

Pump A handoperated water pump comprising a pump body, a piston, ahandle at the upper end of the piston, avalve system connected to the pump body and comprising an inlet and an outlet, wherein the lower end of the piston is provided with a plateand an adjustable tensioner, to tension a piston seal located between the plateand the adjustable tensioner and wherein the adjustable tensioner comprises a spring.

Description

Pump

The present invention relates to a liquid pump, in particular a human

powered water pump. More particularly, the invention relates to a robust water pump suitable for use in developing countries.

The need for access to water for irrigation and household use in developing countries is well known. However, installation of pumps has often been unsuccessful in the long term because spare parts are not available, too expensive or difficult to fit by untrained personnel.

One part that commonly needs to be replaced is the piston seal. This leads to the problems not only of supply and expense but also that incorrect fitting can cause the pump to either leak or to create too much friction between the piston and pump body, making the pump difficult to use.

Another required part is hosepipes. Whilst many designs of pump work well when fitted with high quality hosepipes, the efficacy may decrease when cheap hosepipes are used in their place. United States patent 7,517,306 describes a human powered pump in which an operator places the handle against his/her hip, therefore using his/her body weight to push and pull the handle. The piston seal is a pair of opposed piston cups, for which replacement parts will be required over time. Due to the shape of the piston cups, replacements must be correctly sourced and fitted in order for the pump to work correctly. Likewise, the valve seals have a convex shape, also requiring correctly sourced and fitted replacement parts.

The aim of the present invention is to provide a human powered pump which overcomes these problems.

According to a first aspect of the present invention there is provided a_hand operated water pump comprising:

a pump body; a piston;

a handle at the upper end of the piston;

a valve system connected to the pump body and comprising an inlet and an outlet;

wherein the lower end of the piston is provided with a plate and an adjustable tensioner, to tension a piston seal located between the plate and the adjustable tensioner and wherein the adjustable tensioner comprises a spring.

The invention provides a large tolerance for adjusting the compression of the piston seal, enabling the pump to be easily maintained. It is therefore particularly suitable for use by an untrained and unskilled person.

The spring may comprise a compression spring. In one embodiment, the spring comprises a coiled spring. In another embodiment, the spring comprises a resilient spacer, for example a rubber spacer.

The plate may comprise a washer.

The tensioner may comprise a second plate positioned so that, in use, it abuts the piston seal. The second plate may comprise a washer.

The tensioner may be fully adjusted by hand This has the advantage that no tools are required. The tensioner may comprise at least one nut. For example, the tensioner may comprise a wing nut. The tensioner may comprise two nuts, with the second nut acting as a lock nut.

The pump may further comprise a piston seal located between the plate and tensioner. The piston seal may have been cut out from a pre-used rubber or leather product, such as an inner tyre or shoe.

In one embodiment, the inlet and outlet of the valve system are transverse to the longitudinal axis of the pump body. When the pump is in use, this arrangement results in the inlet and outlet being substantially horizontal; cheap hosepipe can be connected to the substantially horizontal inlet and outlet without kinking.

In one embodiment, the valve system comprises a 'C shaped housing, with the inlet and outlet being substantially parallel to each other. The inlet and outlet valves may be in the central portion of the C shape. This design has the ball valves arranged vertically when the pump is in use, so that they are most effective.

Alternatively, the inlet and outlet valves may be on opposite sides of the main body of the pump, for example in an 'S' shape. The inlet and outlet vales may be in the central portion of the S shape.

The valve system may comprise two one way valves. The valve system may comprise ball valves. The valve system may connect to the pump body via a tube.

The pump may further comprise a stand. The stand may be connected to the pump body via a pivot.

The pump may be self priming. For example, the combination of one way ball valves and good contact between the piston seal and pump body may ensure that the pump is self priming.

A second aspect of the present invention provides a hand operated water pump comprising:

a pump body;

a piston, slideable within the pump body;

a handle at the upper end of the piston;

and a piston seal at the lower end of the piston, wherein the piston seal has been cut out from a pre-used rubber or leather product, such as an inner tyre or shoe.

The piston seal can be replaced using locally available materials and fitted by an untrained and unskilled person using readily available tools. A third aspect of the present invention provides a hand operated water pump comprising: a pump body;

a piston, slideable within the pump body;

a handle at the upper end of the piston;

a valve system connected to the pump body and comprising an inlet and an outlet, wherein the inlet and outlet of the valve system are transverse to the longitudinal axis of the pump body. The simple design of the pump means it has several advantages; it can be used and maintained by anybody without significant training and tools, the pump is affordable and robust and the arrangement of the valve assembly enables cheaper hosepipe to be used.

The pump has sufficient draw to enable water to be pumped from a river bank, reducing the risk of drowning or crocodile attack by people who would otherwise collect water directly from the water with a bucket. This is particularly the case where the river banks are high, creating a risk of falling into the river when collecting water by bucket.

Although some other pumps are capable of pumping water from a river bank, they conventionally require priming; therefore the user first has to endanger himself/herself by collecting a small amount of water from the river to prime the pump.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other moieties, additives, components, integers or steps. Moreover the singular encompasses the plural unless the context otherwise requires: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the invention will become apparent from the following examples. Generally speaking the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings). Thus features, integers or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. Moreover unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose.

The present invention will now be further described with reference to the following non- limiting examples and the accompanying illustrative drawings, of which:

Figure 1 shows the whole pump assembly comprising of the pump body, which includes the valve system, the handle and the stand;

Figure 2 is a side view of the pump body. The cutting plane A-A passes through the valve system; Figure 3 shows a cross section of the valve system, along A-A of Fig 2;

Figure 4 is a side view of the handle sub assembly;

Figures 5A-5C show alternative arrangements of the piston seal of Fig 4;

Figure 6A shows a front view of an alternative valve assembly;

Figure 6B shows a side view of the valve assembly of Fig 6A; Figure 6C shows a cross section along A-A of Fig 6B and

Figure 7 shows an alternative embodiment of the whole pump assembly.

The present invention is a simple, low cost liquid pumping device as shown in Fig 1. The pump 10 is human powered; the user pushes and pulls a handle 12 which drives a piston 13 inside the pump body 14. The user places one or two feet on a stand 16 and leans back on the upstroke and forward on the down stroke. This action utilises the user's body weight to aid pumping, making the operation easier than if arms alone were used.

Replacement parts can be easily made by the user, making the pump suitable for remote locations. The flow of liquid in and out of the pump is controlled by a valve

system 18 consisting of two one-way valves.

The pump comprises of; • The pump body 14, within which the piston travels up and down.

• A valve system 18 at the lower end of the pump body which controls the flow of liquid in and out of the pump body.

• A handle 12 which is operated by the user, directly connected to the piston 13. · A stand 16, which is connected to the pump body about a pivot 20, allowing the pump body to rotate with respect to the stand.

The valve system 18 comprises a housing containing two one way valves mounted onto the pump body with an interconnecting tube joining the valve system and pump body to each other. Figures 1 and 2 show perspective and plan views respectively of the valve housing mounted on the pump body.

The valve system 18 consists of two one-way valves in either a vertical or horizontal orientation. In the vertical orientation, shown in FIG 3, the valve system 18 consists of a cylinder connected to the pump body via an interconnecting tube 21. Below the interconnecting tube, the liquid inlet valve 22 controls the flow of liquid into the pump body. Above the interconnecting tube the liquid outlet valve 24 controls the flow of liquid out of the pump body. In the horizontal orientation, the valve system is split into two parts, the inlet and outlet valves, which are joined to opposite sides of the pump body.

The use of ball valves in the pump has the advantage that the valves will not need to be replaced over the life cycle of the pump. By contrast, pumps using rubber or leather valves will require maintenance and specific replacement parts to replace the valves.

In FIG 3, the one-way valves are shown as ball valves; however, the valves system can be made using any type of one-way valve. In both orientations, the suction and discharge hosepipes can be directly joined to the valve system. In the embodiment illustrated in Fig 3, the suction hosepipe is connected to input 26 and the discharge hosepipe is connected to the output 28.

A piston seal is provided at the base of the piston. The piston seal 32, shown in FIG 4, when worn, can be replaced by a homemade one manufactured by the end user from old inner tubes, other rubber products, or old flip flops. The pumping system utilises flexible hosepipes which allow liquid to be pumped from any location, to any location that is within the pump's range.

The pump can lift liquid from 9m below and push it another 10m vertically. The pump consistently achieves a depth of 6m under all conditions and with all users. Unlike many human powered pumps, this pump is self-priming, even when operating at its maximum depth. The features which enable the pump to be self-priming are the good contact between the piston seal and/or the use of efficient one way ball valves.

At the top of the pump body 14, a small hole 30 (Fig 1) allows excess water, which has bypassed the rubber piston seal 32 (shown in Fig 4), to escape on the upstroke of the piston.

The mechanism of the pump will now be described with reference to Fig 3. Liquid enters the valve system 18 through inlet 26 (point B in Fig 3); it passes through the one-way valve 22 and into the main body 14 of the pump through point (C), the interconnecting tube 22. When the pump's handle is pushed down, the liquid leaves the pump's body 14 through point (C) (interconnecting tube 22) and up through the one-way valve 24, leaving the valve system via point (D) (outlet 28).

The suction hosepipe can be attached around the tube at point (B) (inlet 26), the discharge hosepipe can be attached around the tube at point (C) (outlet 28). The hosepipes can be fixed in place with jubilee clips or commonly available rubber strapping.

The pump body 14 rotates, with respect to the stand 16, about point (E) (pivot

34). This pivot allows the pump body 14 to be rotated about the stand 12. The pump body 14 can fold flat, with respect to the stand 16, making the pump easily transportable.

The bottom of the pump body 14 is sealed by inserting a cap 36, which is held in place with adhesive. Hole 34 (E) is drilled through both the cap and the pump body.

The cap and valves may be injection moulded. FIG 4 shows the handle sub assembly 38. A cap 40 fits inside and locates the handle 12 into the pump body 14. The handle 12 is free to slide through the cap 40. The cap 40 may be held in place by friction alone. The handle 12 is directly connected to the piston 13. The piston seal 32 is made from layers of thin rubber sheet, or an equivalent. They are held in position by washers 42,44 above and below the piston seal 32. The bottom washer 44 is held in place by two nuts 46,48.

The simple design of the pump makes it both robust and suitable for manufacture in the developing countries where it will be used. The pump is low cost and can be manufactured from readily available materials.

The pump body will be made from uPVC or ABS. The tube needs to have a wall thickness of at least 2mm, the inside diameter can vary between 40-60mm. A 40mm internal diameter will be easier to use, but will have a lower output, and a 60mm tube will be able to pump more water with a single stroke, but requires more effort to use. The pump body is 700mm long.

The handle sub assembly is made from two pieces of steel tube, the upright part from 20mm tube and the handle from 25mm tube.

The stand is primarily made of thin walled steel box section (either 16mm or 20mm square), with 3-5 mm thick flat steel making the two uprights. The stand is 700mm long, the width depends on the diameter of the pump body, it can vary from 60mm- 80mm

All steel parts will be galvanised or painted to protect them from moisture. In alternative embodiment, the pump body and valves are metal, for example galvanized steel, stainless steel or aluminium.

Alternative arrangements of the piston seal arrangements will now be described with reference to Figs 5A to 5C. All three figures show the lower end of the handle sub assembly described with reference to Fig 4 and the same reference numerals will be used for identical features. Fig 5A shows the piston seal arrangement described in Fig 4; a single layer of rubber or leather 32 is held between two penny washers 42,44 and is fixed in place by a nut 46. When the nut 46 is tightened onto the seal arrangement, it creates a lateral force that acts across the washers 42,44 and rubber/leather seal 32. This causes the constrained parts of the rubber/leather to compress and the free parts of the rubber/leather to expand. This expansion creates the seal against the plastic body of the pump that is necessary to pump water.

However, over tightening of the nut (onto the seal arrangement), creates over overexpansion of the rubber/leather seal. This generates a large friction force acting between the rubber/leather and the plastic pump body, impeding the pump's performance, making it difficult to operate.

The pump is designed to be used by small scale farmers of little or no education.

Practical testing shows that farmers found it very difficult to correctly tighten the nut. If the nut is not tightened enough then the pump will cease to work since no seal will be created by the rubber/leather seal against the plastic pump body.

One full rotation of an Ml 0 nut will create a lateral movement of 1.5mm, along the treaded section, acting directly on to the seal. The force applied to the rubber/leather is dependent on the spring rate of the rubber/leather. If a single layer of 3mm neoprene rubber is used as the seal, there is an acceptable tightness tolerance of only 0.25 of a turn. This means that once the nut is finger tight, it can only be tightened by another 90 degrees. If it is tightened more than 90 degrees, the friction force will become too great and the pump will be too difficult to use. In a solution to this problem, the inventor has designed alternative piston seal arrangements, as illustrated in Figs 5B and 5C.

Fig 5B shows a second embodiment of the piston seal arrangement. In this embodiment, a rubber spacer 48 is placed between the lower penny washer 44 and the nut 46. Fig 5C shows a third embodiment of the piston seal arrangement, in which a spring 50 is inserted between the lower penny washer 44 and the nut 46. The applicant has discovered that if a spring or rubber spacer is inserted between the nut and the piston seal, the force applied to the seal by the lateral movement of the nut is reduced. This is because some of the force applied by the nut is absorbed by the spring/rubber spacer. One full turn of the nut, without a spring/spacer will create a much larger expansion of the free parts of the rubber/leather than if a spring/spacer is used.

For example, if a 3mm neoprene seal is used along with a 9mm neoprene spacer, the acceptable tolerance increases from 0.25 of a turn up to 2.5 turns. This makes a real difference as it is much easier for the small scale farmer to set a suitable tightness, allowing the pump to function efficiently.

The spring/rubber spacer also exerts a force back onto the nut, this acts in the same way as a spring washer, which helps prevent the nut from loosening.

As the majority of small scale farmers do not have many tools, instead of using a conventional nut, a wing nut can be provided, which allows the famers to set the tightness of the seal using their fingers. The effect of the spring / rubber spacer can be explained using Hooke's law:

Hooke's law of elasticity states that:

F=(-)k*x

(where F is the force applied, k is the spring constant and x is the extension (lateral movement))

A rubber seal can be considered to act like a spring (up to a certain temperature and stress). Therefore the force acting on the rubber seal is dependent on the rubber's spring constant and the extension applied by the lateral movement of the nut. When a spring or rubber washer is inserted between the nut and the seal arrangement, it can be considered that there are two springs in series. The first spring being the rubber/leather seal and the second being the spring/rubber spacer.

To find the spring constant of springs arranged in series l/k_t = 1/ki + l/k₂

The value for k_t will always be less than ki or k₂, therefore the force applied to the seal will be reduced when using the new arrangement, according to F=(-)k_t*x

In another embodiment of the invention, the pump has an alternative valve arrangement as illustrated in Figs 6A-6C.

Fig 6A shows a plan view of the pump body corresponding to that shown in Fig 2 and identical parts having the same reference numbers. In the embodiment of Figs 6A-6C, the valve system 52 has a 'C shape, with a central portion 54 in line with the longitudinal axis of the pump body and the inlet 26 and outlet 28 transverse to it. Figs 6B and 6C show the side view and cross section respectively. The mechanism of the valve assembly will now be described. On the upstroke of the pump, water enters at inlet 26 and flows up through the ball valve 22. Fig 6C shows the ball valve in the closed position, with the ball resting on the valve seat. The water then flows into the pump body through interconnecting tube 21. On the downstroke, water flows back through the interconnecting tube 21 and through the upper ball valve 24; Fig 6C shows the ball in the open position as though water is flowing through it. Water then leaves the pump at outlet 28.

Standard size, 25mm hosepipe can be attached over the input 26 and output 28. They are secured with a jubilee clip or rubber strapping (thin strips of rubber, used to secure many things in Africa, the rubber is wound around the hosepipe and valve section until a watertight seal is made). The alternative valve arrangement has the advantage that the hosepipes are connected substantially horizontally, which minimises kinking. By contrast, in an arrangement with vertical input and output, the hosepipes are liable to kink as they leave the pump in the vertical plane and then have to become horizontal. This is not a problem if high quality hosepipe is purchased, however most small scale farmers will buy the cheapest pipe available and therefore the valve illustrated in Figs 6A-6C is much more suitable.

The valve assembly can be made by injection moulding. An alternative embodiment of the pump assembly is shown in Fig 7. This embodiment is similar to that shown in Fig 1 and similar are given the same reference numerals.

The main difference between the embodiments of Figs 1 and 7 is the arrangement of the valve system. Fig 7 shows that whilst the outlet pipe 66 remains parallel to the pump body 14, the inlet pipe 64 is angled away from the longitudinal axis of the pump body 14. When the pump is in use, this arrangement results in the inlet pipe 64 being substantially horizontal; this prevents the hose connected to the inlet pipe from kinking. In addition, the angle between the main base section 16 and section 62 accommodating the pivot has been increased; in this new configuration the inlet pipe 64 is enclosed by section 62 when the pump is folded, thereby protecting inlet pipe 64.

Claims

1. A hand operated water pump comprising:

a pump body;

a piston;

a handle at the upper end of the piston;

2. A hand operated water pump according to claim 1, wherein the spring comprises a compression spring.

3. A hand operated water pump according to any one of the preceding claims, wherein the spring comprises a coiled spring.

4. A hand operated water pump according to any one of claims 1 to 2, wherein the spring comprises a resilient spacer.

5. A hand operated water pump according to claim 4, wherein the spring comprises a rubber spacer.

6. A hand operated water pump according to any one of the preceding claims, wherein the plate comprises a washer.

7. A hand operated water pump according any one of the preceding claims, wherein the tensioner comprises a second plate positioned so that, in use, it abuts the piston seal.

8. A hand operated water pump according to claim 7, wherein the second plate comprises a washer.

9. A hand operated water pump according to any one of the preceding claims, wherein the tensioner can be fully adjusted by hand.

10. A hand operated water pump according to any one of the preceding claims, wherein the tensioner comprises at least one nut.

11. A hand operated water pump according to claim 10, wherein the tensioner comprises a wing nut.

12. A hand operated water pump according to any one of claims 10 or 11, wherein the at least one nut comprises two nuts.

13. A hand operated water pump according to any one of the preceding claims, wherein the pump further comprises a piston seal located between the plate and tensioner.

14. A hand operated water pump according to any one of the preceding claims, wherein the piston seal has been cut out from a pre-used rubber or leather product, such as an inner tyre or shoe.

15. A hand operated water pump according to any one of the preceding claims, wherein the inlet and outlet of the valve system are transverse to the longitudinal axis of the pump body.

16. A hand operated water pump according to any one of the preceding claims, wherein the valve system comprises a 'C shaped housing, with the inlet and outlet being substantially parallel to each other.

17. A hand operated water pump according to claim 16, wherein the inlet and outlet valves are in the central portion of the C shape.

18. A hand operated water pump according to any one of the preceding claims, wherein the valve system comprises two one way valves.

19. A hand operated water pump according to any one of the preceding claims, wherein the valve system comprises ball valves.

20. A hand operated water pump according to any one of the preceding claims, wherein the valve system connects to the pump body via a tube.

21. A hand operated water pump according to any one of the preceding claims, further comprising a stand.

22. A hand operated water pump according to claim 21 , wherein the stand is connected to the pump body via a pivot.

23. A hand operated water pump according to claim 22, wherein the pump body is foldable against the stand and when folded, the inlet is enclosed by the stand.

24. A hand operated water pump according to any one of claims 1-14, 18 - 23, wherein when the pump is in use, the inlet is substantially horizontal.

25. A hand operated water pump according to any one of the preceding claims, wherein the pump is self priming.

26. A hand operated water pump substantiaiiv as herein described with reference to the accompanying illustrative drawings.