GB2609450A

GB2609450A - Borehole water pump

Info

Publication number: GB2609450A
Application number: GB2111054.9A
Authority: GB
Inventors: Uddin Azeem Islam Azeem; Njuguna James; Muhammad Sukki Firdaus
Original assignee: Kingdom Innovative Tech Ltd
Current assignee: Kingdom Innovative Tech Ltd
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2023-02-08
Also published as: WO2023007193A1; CN118043555A; GB202111054D0

Abstract

A water pump system for use in a borehole, the pump system comprising a pumping chamber (5, fig.5) or cylinder having a piston 4 configured to reciprocate in a direction substantially perpendicular to the borehole axis. The piston 4 may be elongate having a major dimension, wherein the major dimension of the piston head is substantially parallel to the major dimension of the pump housing 18, 20 & 22. A renewable power source, such as a solar powered generator, a wind powered generator, a geothermal energy powered generator or an anaerobic digester, can be used to drive said motion of the piston using an electrical motor 3 located within the borehole. The reciprocating piston motion perpendicular to a vertical borehole axis allows energy to be saved by avoiding vertical piston motion, and a lower-power renewable energy supply can therefore be used.

Description

1 BOREHOLE WATER PUMP

3 Field of the invention

The present invention relates to the pumping of ground water for drinking.

7 Background to the invention

9 Accessing groundwater through a borehole or well is a common technique used to obtain water for drinking or other purposes. Particularly in semi-arid areas of remote 11 regions this is an important way to obtain drinking water. Also common is the use of a 12 pump in order to transport water present in ground water to the surface.

14 The present disclosure addresses how to obtain potable water in a reliable manner from a borehole in an isolated environment.

17 Areas in which water is accessed through a borehole are often rural and remote.

18 Infrastructure relating to the reliable provision of power is often not be available. The 19 use of locally generated power, for example power from a renewable power source such a solar powered source, may play an important aspect. However, renewable 21 power sources are often relatively low power and they typically fluctuate. The present 22 invention seeks to solve this problem.

1 The Apollo-AC Electric Pump from Blackhawk Technology Company is a known pump 2 suitable for pumping liquid from a borehole up to the surface. This known pump has a 3 vertically reciprocating piston with a vertically reciprocating drive rod and a motor 4 located at the surface. Any vertically reciprocating element has to overcome gravity and this is done at the expense of energy.

7 Summary of the invention

9 In an aspect the invention relates to a pump system for use in a borehole, the pump system comprising a pumping chamber having a piston configured to reciprocate in a 11 direction substantially perpendicular to the borehole axis. The pump system comprises 12 a renewable power source, or an electrical interface for receiving energy from a 13 renewable power source, to drive said motion of the piston. Typically, the system 14 comprises an electrical motor which drives said motion of the piston. The electrical motor is typically configured to be located down the borehole.

17 The invention also extends to a pump system for use in a borehole, the pump system 18 comprising a pumping chamber having a piston, and an electrical motor configured to 19 be located down (typically within) the borehole to drive the said motion of the piston.

Typically, the pump system comprises a renewable power source or an interface for 21 receiving energy from a renewable power source. Typically, the piston is configured to 22 make a reciprocating motion in a direction substantially perpendicular to the borehole 23 axis.

The invention also extends to a method of pumping subsurface groundwater up 26 through a borehole to above the ground, the method comprising: receiving power 27 above the ground (typically by collecting renewable energy using a renewable energy 28 generator); and transmitting said power down the borehole to drive a pump with a 29 substantially horizontal reciprocating motion, to thereby pump water to the surface level. Typically the pump comprises a pumping chamber having a piston, and an 31 electrical motor down (typically within) the borehole which is powered by the said 32 power. Typically, the piston is configured to reciprocate substantially horizontally.

34 The motion of the piston relative to (typically within) the pumping chamber pumps water upwards, to the surface, in use, typically through a pipe.

1 The pumping chamber, piston and typically also the electric motor, may be installed in 2 a borehole. The borehole is typically substantially vertical. The borehole typically has 3 an axis. The borehole is typically circular in cross section.

The electrical motor is typically located down the borehole, in use. The electrical motor 6 is typically located within the borehole, in use. The electrical motor may be a 7 submersible motor, that is one capable of operating in an aqueous environment, such 8 as in water.

The pump system typically comprises a housing which retains the pumping chamber 11 and the piston. Typically, the electrical motor is located within or attached to the 12 housing. However, the electrical motor may be located separately to the housing but 13 within the borehole.

Typically, the housing is elongate having a major dimension. The housing may have a 16 longitudinal axis. In use, the housing is fitted within the borehole with its major 17 dimension (and longitudinal axis) parallel to the length of the borehole. Typically, the 18 piston is configured to reciprocate substantially perpendicular to the major dimension 19 of the housing. Thus, where the borehole is vertical, the piston will reciprocate substantially horizontally.

22 A borehole made to access ground water generally passes vertically down into the 23 Earth. It is not unknown that a borehole needs to be made to a depth of 200m in order 24 to access water. A borehole may even need to be made to a depth of 350m. Typically the pumping chamber is located at least lm underground. The pumping chamber may 26 be located less than 350m or less than 250m or less than 100m or less than 50m 27 underground.

29 By configuring a system comprising a piston which makes a reciprocating motion perpendicular to the vertical borehole axis, i.e. a piston which reciprocates backwards 31 and forwards in a horizontal motion, vertical motion of the piston is avoided. Raising a 32 piston vertically requires energy. Even if gravitational potential energy is returned, 33 raising the piston requires a greater force to be exerted than is the case with a piston 34 which reciprocates horizontally in use, leading to greater energy consumption and a requirement for a high power energy source. Energy can therefore be saved, and 36 potentially a lower-power energy supply used, by avoiding vertical piston motion.

1 Substantially perpendicular to the length of the borehole, or the major dimension of the 2 housing, may be at an angle of less than 10° or less than 5° to orthogonal to the length 3 of the borehole. Substantially horizontal may be at angle of less than 10° or less than 4 5° to horizontal.

6 The system typically does not include a drive rod which extends from the surface to the 7 housing, particularly one which reciprocates vertically. This may be highly significant, 8 particularly in the case of a deep borehole, for example one of 200 m depth.

The reduction of the energy required to operate an arrangement in which a piston 11 makes a reciprocating motion substantially perpendicular to the borehole axis, renders 12 the pumping arrangement suitable to be powered by a renewable power source, which 13 may be lower power and/or fluctuating. The renewable power source is typically 14 located above ground in use 16 The renewable power source may for example be a solar powered generator, a wind 17 powered generator, a geothermal energy powered generator or an anaerobic digester.

18 The renewable power source may have a maximum power of less than 10kW or less 19 than 5kW.

21 A solar powered power source may be particularly suitable for powering a pump system 22 in an arid or semi-arid environment associated with strong sunlight.

24 Typically, the renewal power source is a standalone power source which is not connected to an electrical grid. Typically, the pump system is located on land but not 26 connected to an electrical grid.

28 The electrical motor may drive the reciprocating motion directly, or it may drive the 29 reciprocating motion indirectly.

31 The pump system may comprise a rotatable shaft, also called a pump shaft. The 32 electrical motor may be coupled to the rotatable shaft. The electrical motor may drive 33 rotation of the rotatable shaft in use. Typically the rotatable shaft has an axis of rotation 34 which is parallel to the borehole. The rotatable shaft may be located within the housing.

The rotatable shaft may extend from the motor (within the borehole) into or within the 36 housing.

1 Typically the rotatable shaft has an axis of rotation which is parallel to a major 2 dimension of the housing. The rotatable shaft is typically driven by the electrical motor 3 in use.

The pump system may be configured such that rotation of the pump shaft translates to 6 the reciprocating motion of the piston. The axis of rotation of the pump shaft is 7 generally along the longitudinal axis of the pump shaft. In other words, the axis of 8 rotation of the pump shaft is generally vertical, where there is space.

Typically, there is no pump shaft extending between the surface and the housing.

12 Actioning reciprocating motion of the piston through rotation of a pump shaft has the 13 effect that the energy required to move the pump shaft is limited to that required for 14 rotational motion. This is generally a significant reduction on the energy required to move the pump shaft in a vertical direction and/or the maximum power required.

17 The pump system may comprise a converter for converting rotational motion of the 18 pump shaft to translational motion of the piston.

For example, the pump system may comprise a cam, a connecting rod, or a slotted link 21 mechanism, such as a Scotch yoke, to translate rotation of the pump shaft to said 22 reciprocating motion of the piston.

24 In a cam arrangement an eccentric disk or other suitably shaped element rotating with the pump shaft may be used to provide a translational force to the piston head.

27 The system may comprise a connecting rod arrangement to translate rotational 28 movement of the pump shaft to translational movement of the piston head. A 29 connecting rod may be attached with rotational freedom at one end to a body, such as a disc, which rotates together with the pump shaft. The other end of the connecting 31 rod may be attached with rotational freedom to the piston.

33 Typically, the piston comprises a piston head. The piston is typically constrained to a 34 reciprocal piston motion. The motion of the piston head may be constrained by one or more piston guide formations within the housing. The motion of the piston head may 36 be constrained by the pumping chambers. The pumping chamber may be a cylinder 37 within which the piston slides.

2 The motion of the piston head may be constrained to be in a direction perpendicular to 3 the axis of rotation of the pump shaft. In this way, as the pump shaft rotates, the disc 4 rotates with the pump shaft and the connecting rod transmits this movement to the piston head which translates in a reciprocating manner. Thus, the motion of the piston 6 head is constrained to be horizontal in use, in a vertical borehole.

8 A Scotch yoke, otherwise known as a slotted link mechanism, may provide a means 9 for transmitting and transforming the rotational motion of the pump shaft to a reciprocating motion of the piston head. The system configuration is such that the axis 11 of rotation of the pump shaft generally coincides with the longitudinal axis of the pump 12 shaft. The inclusion of a Scotch yoke arrangement may be associated with the pump 13 shaft comprising an off-axis shaft portion which engages with a sliding yoke attached 14 to the piston shaft. The off-axis shaft portion acts as a shaft slider and resides in a channel of the piston. The shaft slider slides within the channel, which extends 16 horizontally. As the pump shaft rotates, the shaft slider navigates a circular path. The 17 circular navigation of the shaft slider, together with the constraints of the piston cylinder 18 and possibly also by any piston support mechanism on the piston, thereby force the 19 piston into a translational motion, which reciprocates as the shaft slider rotates in a circular fashion. The shaft slider may comprise bearings to reduce friction between the 21 shaft slider and the channel. An increase in efficiency is thereby achieved.

23 The pump shaft may take the form of a rod. The pump shaft may take the form of a 24 plurality of rods aligned along a single axis. This may be necessary if a continuous rod would interfere with the converter mechanism for converting rotational motion of the 26 pump shaft to translational motion of the piston.

28 The power source may be arranged to drive a motor configured to drive said motion of 29 the piston. Preferably, configuration of the system is such that the motor drives rotation of the pump shaft. The rotation of the pump shaft then causes the motion of the piston.

31 In this way, the motor drives the motion of the piston via rotation of the pump shaft.

33 This has the advantage that the motor may be located distant from the piston. This is 34 particularly advantageous if the piston is placed down a borehole, which is an inconvenient location should maintenance of the motor be required. Thus there may 36 be embodiments in which the motor is located at or above ground level in a convenient 1 location for maintenance and the pump shaft extends down the borehole from the 2 motor to the piston.

4 It may be that the piston head is elongate having a major dimension. It may be that the pumping chamber is elongate having a major dimension. Typically the piston head and 6 pumping chamber are each elongate in the same direction. Typically, the major 7 dimension of the piston head is substantially parallel to the major dimension of the 8 housing. It may be that the major dimension of the pumping chamber is parallel to the 9 major dimension of the housing. Thus, the major dimension of the piston head is typically substantially vertical. Thus, the major dimension of the pumping chamber is 11 typically substantially vertical. The major dimension of the piston head is typically 12 substantially parallel to the axis of rotation of the rotatable shaft. The major dimension 13 of the pumping chamber is typically substantially parallel to the axis of rotation of the 14 rotatable shaft. The major dimension of the piston head may be greater than 50%, greater than 75% or even greater than 100% the maximum diameter of the housing.

16 The major dimension of the pumping chamber may be greater than 50%, greater than 17 75% or even greater than 100% the maximum diameter of the housing.

19 Thus pump capacity is maximised within the confined space of a borehole. The stroke volume of the piston within the pumping chamber can be greater than would be the 21 case if the piston head and pumping chamber were not extended along the length of 22 the borehole in this way.

24 The pump system may comprise a piston head which is rectangular or oval in shape.

In this case, the major dimension will typically be the long axis of the rectangle or oval.

27 A rectangular piston head may offer relative ease of manufacture. A piston head which 28 is oval in shape offers several advantages. A piston head which is oval in shape lacks 29 sharp corners, with the result that there is decreased wear of any seal around the piston head edge and increased seal durability.

32 The piston head may have a major dimension which is along the length of the borehole 33 axis. The piston head may have a major dimension which is along the length of the 34 housing axis. The piston head may have a major dimension parallel to the length of the pump shaft.

37 The pump system (e.g. the housing) may comprise at least one piston support.

2 A piston support may take the form of a rod which is attached to the rear side (side 3 opposite the pumping chamber) of the piston and which engages with a corresponding 4 support channel. The corresponding support channel may be mounted on a housing or a housing of the pump. A support channel may comprise guided bearings for 6 bearing, supporting and guiding the piston support rod.

8 There may be more than one piston support rod, each with a corresponding support 9 channel. Each support channel may comprise guided bearings. For example, there may be four piston support rods arranged around the piston head, and four 11 corresponding support channels each with guided bearings.

13 A piston support rod attached to the piston, and in an engaged arrangement with a 14 corresponding support channel comprising guided bearings for bearing, supporting and guiding the rod, provides the piston with structural support beyond that of the piston 16 shaft. This has the effect of reducing the mechanical stress within the piston head, the 17 piston head otherwise being responsible for transferring any force from (or to) the 18 piston shaft.

At least one piston support may connect to the piston head in a filleted connection.

22 A filleted connection between a piston support rod and the piston head further helps to 23 spread the stress burden on the piston head. The fillets distribute the stress over a 24 broader area, reducing stress concentration on the piston head and effectively making the piston head more durable.

27 The pump system (e.g. the housing) may comprise a biasing means, for example a 28 sprung arrangement, configured to return the piston head after a discharge stroke.

The sprung arrangement configured to return the piston head after a discharge stroke 31 may take the form of a spring or a plurality of springs. The sprung arrangement may 32 exert a force on the piston head which is opposite in direction to the force exerted on 33 the piston head originating from the pump shaft. The sprung arrangement may exert 34 a force on the piston head which is opposite in direction to the force exerted on the piston head originating from the pump shaft and transferred to the piston head through 36 a cam. The cam may be on the pump shaft.

1 Typically, the housing defines the pumping chamber. Typically, the piston reciprocates 2 within or around the pumping chamber. The pumping chamber typically has a cross- 3 section which cooperates with the shape of the piston.

The pump shaft may pass through the housing.

7 The pump system may comprise a pipe extending along the borehole. The pipe may 8 transport the liquid being pumped, typically water, from a source to the surface. The 9 housing may be configured so that it is connectable to this pipe. The housing may comprise an inlet to which the pipe is connectable (or connected in use) and into which 11 water is intended to pass when being pumped from a water source. The housing may 12 comprise an outlet to which the pipe is connectable (or connected in use) and from 13 which water is intended to pass when being pumped to the surface. Alternatively, the 14 inlet for the water and the outlet for the water may form part of the pipe, which pipe may be configured to be attachable to the housing.

17 The housing may comprise housing support for the at least one piston support. A 18 housing support may take the form of a channel within which a piston support fits. The 19 channel may be fixedly attached to the housing. Bearings may be provided to facilitate a low friction motion of a piston support within a housing support as the piston 21 reciprocates.

23 The pump system may comprise at least one bearing supporting rotation of the pump 24 shaft.

26 The housing may comprise at least one bearing supporting or intended to support 27 rotation of the pump shaft. A bearing may be positioned where the pump shaft 28 traverses an outer wall of the housing. The pump shaft may pass through the housing, 29 in which case the pump shaft may pass through an outer wall of the housing twice. A bearing intended to support rotation of the pump shaft may be present at each position 31 where the pump shaft traverses the housing wall. One of more bearings intended to 32 support rotation of the pump shaft may be present within the housing. Bearings within 33 the housing may be additional to bearings present at the housing walls, or they may be 34 alternative to bearings present at the housing walls.

36 The piston head may be connected to a connecting rod, which connecting rod drives 37 motion of the piston head.

2 The connecting rod may be filleted. That is, the cross-sectional area of the pump shaft 3 may increase approaching the piston head, reaching a maximum area at the contact 4 surface. A pump shaft which is filleted in this way distributes the stress exerted on the piston head over a larger area effectively increasing durability of the elements.

7 The pump shaft may be filleted, typically in the vicinity of the off-axis shaft portion.

8 Filleting of the pump shaft strengthens the mechanical structure.

Typically power may be collected at the surface level using a renewable power source.

11 This may typically deliver power in a fluctuating manner. Examples of a fluctuating 12 renewable power source are a solar powered generator, a wind powered generator, 13 and a geothermal energy powered generator.

In addition to the advantages already mentioned above, the system and method of the 16 present disclosure eliminates the requirement for components traditionally found in 17 piston pump systems, such as transmission gears, connecting-rods and stuffing boxes.

18 Furthermore, as the motor can be connected with the piston through a rotating pump 19 shaft, a long drive rod can be avoided. The system and method of the present disclosure are thus well suited to a remote rural environment.

22 Description of the Drawings

24 An example embodiment of the present invention will now be illustrated with reference to the following Figures in which: 27 Figure 1 shows a pump unit comprising a piston and piston chamber attached to the 28 piping. The circumference of the borehole is indicated.

Figure 2 shows the pump system of Figure 1 stripped of components to illustrate a 31 filleted fitting between pump shaft and the Scotch yoke mechanism for transferring 32 motion, as well as bearings supporting the pump shaft.

34 Figure 3 shows the Scotch yoke mechanism for transferring rotational motion to piston displacement motion.

1 Figure 4 is a view of the rear side of a piston head including the piston cylinder, the 2 yoke, supporting panels and piston supports.

4 Figure 5 shows the main housing body including the piston cylinder and support channels for the piston supports.

7 Figure 6 shows a connecting rod mechanism for transferring rotational motion to piston 8 displacement motion.

Figures 7(a), 7(b) each show a cam arrangement for transferring rotational motion to 11 piston displacement. The spring arrangement for returning the piston head after a 12 discharge stroke is also seen.

14 Detailed Description of an Example Embodiment

16 Figure 1 is a schematic diagram of an assembled pump unit 1 with front cover 18, main 17 housing body 20 (transparently shown with internal components) and back cover 22.

19 In this example embodiment, the circumferential lines 2 around the pump unit shows a diameter of 8.98 inches (228 mm) which means that the design is within the 1-inch 21 (25.4 mm) tolerance for a 10-inch (254 mm) borehole size constraint. An arbitrary 22 clearance of 1.5 mm was assumed between the rectangular channel and the housing 23 back cover to accommodate any backward deformation within the piston and the shaft.

The pump unit comprises an inlet 13 at its base and an outlet 16 for water on its top 26 surface. The front cover, inlet and outlet, function as a pipe section which can be 27 integrated into a vertical water pipe within a borehole with the housing body and back 28 cover mounted thereto.

Movement of groundwater from the inlet to the outlet and up to the surface is driven by 31 the motion of piston head 4 which reciprocates in a horizontal direction within piston 32 chamber 5. The reciprocating motion is perpendicular to the vertical axis of the 33 borehole. The orientation of the pump unit and thus the piston within the borehole is 34 determined by the elongate external shape of the pump unit and by the orientation of the outlet which is arranged to couple to a vertical outflow pipe.

1 An advantage of the horizontal direction of movement of the piston is that the piston 2 head can be elongate, parallel to the borehole length, within the pump, resulting in an 3 increase in piston displacement volume with smaller stroke length and slow pump 4 speed. A displacement of 1 litre discharge per stroke may be obtained.

6 The piston motion is driven by pump shaft 7 which rotates about its axis in use driven 7 by an electric motor 3. In the embodiment example illustrated in Figure 1, the rotation 8 of pump shaft 7 is supported by four shaft bearings 19, one at each end of the housing, 9 and two located within the housing.

11 In this embodiment illustrated in Figure 1, rotational motion of the pump shaft 7 is 12 transformed to translational reciprocating motion of the piston via a Scotch yoke 13 mechanism. The piston head 4 is fitted to a slider or yoke 8, which can be seen in the 14 Figure 1. The piston, comprising piston head 4, piston stem 36 and fillets 38 reciprocates in a horizontal direction within the piston cavity. A gasket around the 16 piston head seals the piston cavity off from the inside of the housing.

18 Figure 2 illustrates the pump system of Figure 1 but without several externally visible 19 features, viz, the housing, the piping and the piston chamber. Two internal shaft bearings are each supported by a mount 17 which is fixedly attached to the back cover 21 of the housing 22.

23 Pump shaft] comprises fillets 38 adjacent to the internal bearings 19. These fillets 38 24 support smooth flow of stresses when load is applied, i.e. when the pump shaft rotates, particularly when it starts to rotate from a stationary situation.

27 Also visible in Figure 2 are four rods on the rear side (side opposite the pumping 28 chamber) of the piston head 4. These support the piston head 4 and will be described 29 in greater detail below.

31 Figure 3 shows the embodiment further stripped of features in order to expose the 32 Scotch yoke mechanism (in this figure in combination with a rectangularly shaped 33 piston head). As seen in Figure 3, the slider or yoke 8 is connected to the piston head 34 4 via a connecting rod 40. Piston stem 36 provide additional support for the piston head 4. As the pump shaft 7 rotates around its own axis, shaft pin 10 traces out a 36 circular path and the shaft pin 10 moves back and forth within the yoke 8, driving motion 37 of the piston 4 in the only available way, i.e. reciprocating horizontal motion, as the 1 shaft pin moves back and forth within the yoke. The shaft pin 10 may comprise 2 bearings to reduce friction with the yoke 8.

4 Piston supports help to constrain movement of the piston. In Figure 3 the four rods 34 attached to the rear side (side opposite the pumping chamber) of the piston head 4 6 form part of the piston support. Figure 4 illustrates the piston head 4 (oval shaped) 7 viewed from the rear side (side opposite the pumping chamber) and shows four support 8 rods 34. The yoke 8 of the Scotch yoke is clearly seen, as is the piston stem 36. Fillets 9 38 on each of the piston shaft and the support rods 34 support bending of the piston head 4 on the application of load.

12 Each support rod 34 engages with guided bearings present in a support channel 31 13 which may be fixedly attached to the housing of the pump system. An illustration of 14 the housing is shown in Figure 5. Figure 5 shows the cylinder cavity which is formed from the housing. Also visible are four channels 31 for receiving the support rods 34 16 attached to the rear side (side opposite the pumping chamber) of the piston head 4. In 17 the illustrated embodiment the channels 31 are fixedly attached to the housing. Each 18 of these channels may comprise a shaft guided bearing to help support and guide with 19 minimum friction the reciprocating motion of the support rod 34. Linear shaft guided bearings are feasible for slow motion with less friction than for crossheads sliding on 21 crossways normally found in a piston pump. For instance, using bearings, the friction 22 is reduced due to lower coefficient of friction compared to sliding i.e. 0.0015 -0.002 for 23 ball bearings and 0.08-0.20 for steel on steel sliding. The allowable linear speed for 24 a linear guided bearing is also high ranging 2-5 m/s (compact series), which means that higher revolutions from 752-1880 rpm can be achieved (e.g. for a 2-inch stroke).

26 These bearings are also lubricated, sealed and made with corrosion resistant 27 materials.

29 Figure 6 illustrates a connecting rod mechanism 40, this being an alternative to the Scotch yoke mechanism for converting rotational motion of the pump shaft to 31 reciprocating translational motion of the piston head 4.

33 A further mechanism for converting rotational motion of the pump shaft to reciprocating 34 translational motion of the piston head is one based on a cam 25, as illustrated in Figure 7. The cam shaft pushes forward the piston through the in-contact bearing during the 36 piston discharge stroke. The cam mechanism requires springs 28 to pull the piston 37 head 4 back after it has been pushed away by the cam. The reciprocating piston 1 motion is supported by the piston-supports 34 which reciprocate within the support 2 channels 31 containing linear bearings inside. One possible drawback of this cam 3 system over the Scotch yoke particularly is the mismatch of the timing between the 4 shaft rotation during discharge stroke and pulling back of the springs during intake. The deviation in cam shaft rotational speed causes rolling slippage. If the pump speed 6 increases, the timing to pull back the piston could mismatch resulting in the 7 incompletion of the strokes particularly the intake stroke which solely rely on springs' 8 retraction. If any of the four springs lose retraction force (i.e. show slow retraction or 9 unmatched retraction than other springs set) then again jeopardising the completion of intake stroke plus one side of piston may tilt against the cylinder wall enhancing seal 11 wear. In other words, piston motion is not strongly linked with the shaft motion and 12 relies partially on the springs. Additionally, every forward stroke has to overcome 13 additional initial springs' excitation force to initiate the discharge, thus consuming 14 additional power. These issues make the cam mechanism a less desirable one, although still usable.

17 In all embodiments, it is rotation of pump shaft 7 which drives the reciprocating motion 18 of the piston which in turn leads to pumping of groundwater. A motor, typically an 19 electrical motor, rotates the pump shaft. The motor 3 may be positioned on the housing, or near the housing. Such an arrangement is illustrated in Figure 1.

21 Alternatively, the motor may be placed distant from the housing, for example at ground 22 level. The power for the motor is provided by a renewable power source, such as a 23 solar panels. Renewable power sources are typically relatively low power and typically 24 fluctuating. Electrical cabling is typically used to transmit electricity generated by the renewable power source and the motor.

27 Translation of a vertical pump shaft, including reciprocating translation, requires gravity 28 to be overcome. This is not the case for rotation of a pump shaft around its axis.

29 Energy is thereby saved by rotating a pump shaft along its axis. The energy required to displace the piston horizontally is relatively low and the elongate nature of the piston 31 enables a large stroke volume. Furthermore, the parts of the pump are relatively few in 32 number and can be expected to work reliably for long period of time. Accordingly an 33 efficient pump suitable for use with renewable energy sources in remote areas is 34 provided.

36 Reference numerals 1 1 pump unit 2 2 circumferential lines 3 3 electric motor 4 4 piston head 5 piston chamber 6 7 pump shaft 7 8 slider/yoke 8 10 shaft pin 9 13 inlet 16 outlet 11 17 bearing support 12 18 housing front 13 19 shaft bearings 14 20 housing mid section 21 housing 16 22 housing back cover 17 25 cam 18 28 biasing means 19 31 channel 34 support rod 21 36 supporting panel 22 38 fillets 23 40 connecting rod mechanism

Claims

1 Claims 3 1. A pump system for use in a borehole, the pump system comprising a pumping 4 chamber having a piston configured to reciprocate in a direction substantially perpendicular to the borehole axis, and a renewable power source, or an 6 electrical interface for receiving energy from a renewable power source, to drive 7 said motion of the piston.9

2. A pump system according to claim 1, comprising an electrical motor which drives said motion of the piston and is configured to be located down the 11 borehole.13

3. A pump system for use in a borehole, the pump system comprising a pumping 14 chamber having a piston, and an electrical motor configured to be located down the borehole to drive the said motion of the piston.17

4. A pump system according to claim 2 or claim 3, wherein the pumping chamber, 18 piston and the electric motor are installed in a borehole.

5. A pump system according to claim 4 wherein the pumping chamber is located 21 at a depth of at least lm and less than 350m underground.23

6. A pump system according to any one preceding claim, comprising a housing 24 which retains the pumping chamber and the piston.26

7. A pump system according to claim 6, wherein the electrical motor is located 27 within or attached to the housing.29

8. A pump system according to claim 6 or claim 7, wherein the housing is elongate having a major dimension and fitted within the borehole with its major 31 dimension parallel to the length of the borehole, and wherein the piston is 32 configured to reciprocate substantially perpendicular to the major dimension of 33 the housing.

9. A pump system according to any one preceding claim which does not include 36 a drive rod which extends from the surface to the housing.1

10. A pump system according to any one preceding claim, wherein the renewable 2 power source is a solar powered generator, a wind powered generator, a 3 geothermal energy powered generator or an anaerobic digester.

11. A pump system according to any one preceding claim, wherein the renewable 6 power source may have a maximum power of less than 10kW or less than 5kW 7 and/or wherein the pump system is located on land but not connected to an 8 electrical grid.

12. A pump system according to any one preceding claim, comprising a rotatable 11 pump shaft, wherein the electrical motor is coupled to the pump shaft to drive 12 rotation of the pump shaft in use, and configured such that rotation of the pump 13 shaft translates to the reciprocating motion of the piston, the pump system 14 comprising a converter for converting rotational motion of the pump shaft to translational motion of the piston.17

13. A pump system according to claim 12, wherein the pump shaft has an axis of 18 rotation which is parallel to the borehole and/or the major dimension of the 19 housing 21

14. A pump system according to claim 12 or claim 13, wherein the pump system 22 comprises a cam, a connecting rod, or a slotted link mechanism, such as a 23 Scotch yoke, to translate rotation of the pump shaft to said reciprocating motion 24 of the piston.26

15. A pump system according to any one of claims 12 to 14, comprising a cam 27 arrangement an eccentric disk or other suitably shaped element rotating with 28 the pump shaft to provide a translational force to the piston head, and/or a 29 connecting rod arrangement to translate rotational movement of the pump shaft to translational movement of the piston head.32

16. A pump system according to any one preceding claim, wherein the piston 33 comprises a piston head, wherein the piston is constrained to a reciprocal 34 piston motion and wherein the pumping chamber is a cylinder within which the piston slides.1

17. A pump system according to claim 16, wherein the motion of the piston head is 2 constrained to be in a direction perpendicular to the axis of rotation of the pump 3 shaft.

18. A pump system according to claim 16 or claim 17, wherein the piston head is 6 elongate having a major dimension, wherein the major dimension of the piston 7 head is substantially parallel to the major dimension of the housing.9

19. A pump system according to claim 18, wherein the major dimension of the piston head is greater than 100% the maximum diameter of the housing.12

20. A pump system according to any one preceding claim, comprising at least one 13 piston support.

21. A pump system according to claim 20, wherein the piston support takes the 16 form of a rod which is attached to the rear of the piston and which engages with 17 a corresponding support channel, which support channel comprises guided 18 bearings for bearing, supporting and guiding the piston support rod.

22. A pump system according to claim 20 or 21, comprising more than one piston 21 support rod, each with a corresponding support channel comprising guided 22 bearings.24

23. A pump system according to any one of claims 12 to 22, wherein the pump shaft is filleted.27

24. A method of pumping subsurface groundwater up through a borehole to above 28 the ground, the method comprising: receiving power above the ground by 29 collecting renewable energy using a renewable energy generator; and transmitting said power down the borehole to drive a pump with a substantially 31 horizontal reciprocating motion, to thereby pump water to the surface level.33

25. A method according to claim 24, wherein the pump comprises a pumping 34 chamber having a piston, and an electrical motor down the borehole which is powered by the said power, wherein the piston is configured to reciprocate 36 substantially horizontally.