Drive assembly

Abstract

Embodiments are disclosed of a drive assembly for an electric power generator comprising a rotor shaft that is at least partially submersed in a fluid and has one or more projections that are arranged to extend away therefrom peripherally therearound. The projections are adapted to engage with an object that has a density lower than a density of the fluid, whereby a buoyant force of the object rising through the fluid drives the projections to rotate the rotor shaft. The rotor shaft locates at least partially within a chamber containing the fluid. The chamber has an inlet at a lower portion thereof through which the object is able to enter the chamber below the projections and an airlock that connects to the inlet from which the object is released into the inlet. The inlet is adapted to separate air received from the airlock before delivering the object into the chamber.

Description

DRIVE ASSEMBLYTechnical Field

[0001] This disclosure relates generally to electric power generation, and in particular to drive assembly for an electric power generator.Background

[0002] Many methods and devices have been developed to generate electricity. For example, electrical power can be generated by the combustion of natural resources such as wood, coal, oil, or gas. These methods, however, also produce harmful pollutants and consume natural resources. A variety of renewable and sustainable power generation methods have also been devised including solar, wind, geothermal and hydro electrical power generation.

[0003] Hydroelectric power generation is a generally emission free and reliable method of producing electricity. However, hydroelectric power generators, typically in the form of pumped- storage hydroelectricity (PSH), requires specific geographical conditions in order to have sufficient height and water availability for operation. In addition, the losses of the pumping process to return the water to the elevated storage renders PSH a net consumer of electrical power even before the electricity produced is transmitted from the power generation location to the site where the electricity is needed.

[0004] There may be a need for an assembly capable of generating electrical power that is emission free and reliable. There may also be a need for assembly capable of generating electrical power that may operate continuously and relatively efficiently.Summary of the Disclosure

[0005] In a first aspect, embodiments are disclosed of a drive assembly for an electric power generator. The drive assembly comprises a rotor shaft that is at least partially submersed in a fluid. The rotor shaft has one or more projections that are arranged to extend away from the rotor shaft peripherally therearound. The projections are adapted to engage with an object that has a density lower than a density of the fluid, whereby a buoyant force of the object rising through the fluid drives the projections to rotate the rotor shaft. The rotor shaft locates at least partially within a chamber containing the fluid. The chamber has an inlet at a lower portion thereof through which the object is able to enter the chamber below the projections and an airlock that connects to the inlet from which the object is released into the inlet. Theinlet is adapted to separate air received from the airlock before delivering the object into the chamber.

[0006] In some embodiments, the inlet may comprise a first aperture through which the object enters the inlet, a second aperture through which the object is delivered into the chamber, and a body that extends therebetween, the body having one or more openings through an upper surface thereof that are adapted to vent the air that enters the inlet from the airlock. In some embodiments, the one or more openings may laterally displace the air from the second aperture of the inlet.

[0007] In some embodiments, the airlock may comprise a lower first valve and a higher second valve. A space between the first and second valves defines a compartment adapted to store the object prior to entry into the chamber. In some embodiments, the first and second valves may be configured such that when the first valve is open the second valve is closed, and when the second valve is open the first valve is closed. In some embodiments, when the first valve is open the fluid may be allowed to drain from the compartment and the object may be loaded therein. In some embodiments, when the second valve is open the fluid from the chamber may be allowed to fill the airlock compartment, and the object within the airlock compartment may be released to rise through the second valve and into the chamber. In some embodiments, the first and second valves may be operable to open and / or close via a control system. In some embodiments, the control system may comprise a mechanical timer and / or an electronic processor.

[0008] In some embodiments, the chamber may further comprise an outlet at an upper portion thereof through which the object is able to exit from the chamber. In some embodiments, the outlet may be connected to the inlet via a tube that facilitates the return of the object exiting the outlet to the inlet. In some embodiments, the tube may comprise a low friction liner therein. In some embodiments, the tube may comprise a drainage hole through which the fluid drained from the airlock compartment is able to flow from the tube. In some embodiments, the fluid flowing through the drainage hole may be stored in a catchment and / or recycled into the chamber. In some embodiments, the fluid in the chamber may be replenished from a mains supply.

[0009] In some embodiments, the assembly may comprise a control system that is configured to detect when the chamber requires an additional volume of the fluid to be supplied, and to supply the additional volume of the fluid. In some embodiments, the control system may comprise a float valve.

[0010] In some embodiments, the assembly may comprise a plurality of the object / s. In some embodiments, the object / s may be spherical. In some embodiments, the object may contain a filling comprising air. In some embodiments, the object may contain a filling comprising polystyrene, and may have an external coating comprising polyurethane.

[0011] In some embodiments, the fluid may be liquid. In some embodiments, the fluid may be water.

[0012] In some embodiments, the projections may correspond, at least in part, to the shape and dimensions of the object, so as to releasably receive and engage with the object. In some embodiments, the projections may comprise an aperture adapted to releasably receive and engage with the object.

[0013] In some embodiments, the drive assembly may comprise a second shaft in vertically spaced relation to the rotor shaft, the rotor shaft and second shaft being coupled together by a belt having the projections arranged to extend substantially perpendicularly away therefrom.

[0014] In some embodiments, the chamber may be elongate in a vertical direction.

[0015] In some embodiments, the chamber may comprise a dividing wall that separates a first portion of the chamber having the rotor shaft and a second portion of the chamber above which the inlet delivers the object into the chamber. In some embodiments, the inlet may comprise a guide elbow, the guide elbow being adapted to guide the object through the second portion of the chamber and into the first portion of the chamber. In some embodiments, the guide elbow may comprise one or more apertures adapted to separate and vent the air received from the airlock away from the object and into the second portion of the chamber before the object enters the first portion of the chamber.

[0016] Also disclosed in an electrical power system comprising the drive assembly as described above and a rotor and a stator. The rotor is coupled to the rotor shaft and arranged to rotate relative to the stator so as to generate electrical power.

[0017] In some embodiments, the rotor shaft may be coupled to a flywheel.

[0018] Also disclosed is a method of driving a rotor shaft for an electric power generator, the rotor shaft being at least partially submersed in a fluid and having one or more projections arranged to extend away from the rotor shaft peripherally therearound, the rotor shaft being located at least partially within a chamber containing the fluid, the chamber having an inlet at a lower portion thereof through which an object is able to enter the chamber below the projections and an airlock that connects to the inlet from which the object is released intothe inlet, the method comprising releasing an object into the fluid via the inlet, the inlet being adapted to separate air received from the airlock before delivering the object into the chamber, the object having a density lower than a density of the fluid; and engaging a respective one of the projections with the object whereby a buoyant force of the object rising through the fluid drives the projection to rotate the rotor shaft.

[0019] Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of inventions disclosed.Description of the Figures

[0020] The accompanying drawings facilitate an understanding of the various embodiments. The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0021] Figure 1A is a cross-section front view of an embodiment of a drive assembly for an electric power generator, where the lower first valve is in an open configuration and the higher second valve is in a closed configuration.

[0022] Figure IB is a cross-section front view of the embodiment of Fig. 1A, where both of the lower first valve and the higher second valve are in a closed configuration with an object temporarily stored in the airlock compartment defined therebetween.

[0023] Figure 1C is a cross-section front view of the embodiment of Fig. 1A, where the lower first valve is in a closed configuration, and the higher second valve is in an open configuration.

[0024] Figure ID is a cross-section front view of the embodiment of Fig. 1A, where both of the lower first valve and the higher second valve are in a closed configuration with fluid temporarily stored in the airlock compartment defined therebetween.

[0025] Figure IE is a cross-section front view of the embodiment of Fig. 1A, where the lower first valve is in an open configuration and the higher second valve is in a closed configuration, allowing the fluid to drain from the airlock compartment and a new object to enter for temporary storage within the airlock compartment.

[0026] Figure 2A is a cross-section front view of a second embodiment of a drive assembly for an electric power generator, having a partitioned chamber, where the lower first valve isin an open configuration and the higher second valve is in a closed configuration.

[0027] Figure 2B is a cross-section front view of the embodiment of Fig. 2A, where both of the lower first valve and the higher second valve are in a closed configuration with an object temporarily stored in the airlock compartment defined therebetween.

[0028] Figure 2C is a cross-section front view of the embodiment of Fig. 2A, where the lower first valve is in a closed configuration, and the higher second valve is in an open configuration.

[0029] Figure 2D is a cross-section front view of the embodiment of Fig. 2A, where both of the lower first valve and the higher second valve are in a closed configuration with fluid temporarily stored in the airlock compartment defined therebetween.

[0030] Figure 2E is a cross-section front view of the embodiment of Fig. 2A, where the lower first valve is in an open configuration and the higher second valve is in a closed configuration, allowing the fluid to drain from the airlock compartment and a new object to enter for temporary storage within the airlock compartment.

[0031] Figure 3 is a perspective side view of an embodiment of an inlet comprising a plurality of valves and a airlock compartment therebetween.

[0032] Figure 4A is a close-up cross-section front view of a third embodiment of a drive assembly for an electric power generator, having a partitioned chamber, where both the lower first valve and the higher second valve are in a closed configuration, with an object temporarily stored in the airlock compartment defined therebetween.

[0033] Figure 4B is a cross-section front view of the embodiment of Fig. 4A, where the lower first valve is in a closed configuration, and the higher second valve is in an open configuration, allowing the fluid to flood the airlock compartment whereby the object is able to rise through the second valve and inlet.

[0034] Figure 4C is a cross-section front view of the embodiment of Fig. 4A, where both of the lower first valve and the higher second valve are in a closed configuration with fluid temporarily stored in the airlock compartment defined therebetween.

[0035] Figure 4D is a cross-section front view of the embodiment of Fig. 4A, where the lower first valve is in an open configuration and the higher second valve is in a closed configuration, allowing the fluid to drain from the airlock compartment and a new object to enter for temporary storage within the airlock compartment.

[0036] Figure 5A is a perspective view from below of an embodiment of the lowest point of curvature of the feed tube.

[0037] Figure 5B is a perspective view from within the feed tube of an embodiment of the lowest point of curvature of the feed tube.

[0038] Figure 6a is a side view of an embodiment of a braced projection having a planar outer distal edge.

[0039] Figure 6b is a side view of an embodiment of a braced projection having an upturned outer distal edge.

[0040] Figure 7 is a side view of an embodiment of a drive assembly for an electric power generator, having a manually operated mechanical control system to operate the valves.Detailed Description

[0041] Referring to the Figures, a drive assembly 100 is shown in accordance with the present disclosure. The drive assembly 100 comprises at least one rotor shaft 10 that is driven to rotate through the operation of the assembly 100, the rotor shaft 10 being coupled to a rotor of an electric power generator, not shown, and arranged to rotate relative to a stator of the electric power generator so as to generate electrical power. Where like reference numerals are used in the following description, the features are considered to be the same unless specified as being otherwise.

[0042] The rotor shaft 10 is located at least partially within a chamber 20 that contains a fluid 90, with the rotor shaft 10 being arranged such that it is at least partially submersed in the fluid 90. The rotor shaft 10 comprises at least one projection 12 that is arranged to extend radially away from the rotor shaft 10 to a distal end. Preferably, the rotor shaft 10 comprises a plurality of the projections 12 that are spaced at substantially even intervals peripherally around the circumference of the shaft 10. The rotor shaft 10 is driven in-use by one or more objects 30 engaging with the one or more projection / s 12 as they rise through the fluid 90. The object / s 30 must have a density lower than the density of the fluid 90, whereby the resulting pressure difference causes in a net upward force on each of the object / s 30 which in turn applies a net force on the engaged projection / s 12 that are arranged to project across the path of the object / s 30 as they float upwards through the fluid 90.

[0043] As would be appreciated by a person skilled in the art, the fluid could be a large range of gaseous or liquid substances, provided that the object has a density that is lower than the density of the fluid. The magnitude of the buoyancy force applied by the object / s 30 as it travels upward through the fluid 90 is proportional to the pressure difference, and is equivalent to the weight of the fluid 90 that would otherwise occupy the submerged volumeof the object 30, i.e. the displaced fluid 90. The object / s 30 will float with an upward thrust towards the upper surface of the fluid 90, and towards the top of the drive assembly 100 and settle at a level where the object 30 displaces the same weight of fluid 90 as the weight of the object 30. For example, in one embodiment the fluid can be a liquid such as water, and the object can contain a filling comprising air or a gas lighter than air such as helium or hydrogen, or a combination thereof having a resulting density that is lower than the density of water. In a further example, the object can contain a filling comprising polystyrene in either a solid or foam form, and having an external coating comprising a lining of polyurethane or a similar non porous material. In a further example, the object can have a plastic spherical shell with a polystyrene filling in either a solid or foam form. The object may be formed from virgin or recycled materials.

[0044] An inlet 22 is provided at a lower portion of the chamber 20, such as through a base surface 26 of the chamber, with the inlet 22 being positioned and aligned such that an object 30 entering the chamber 20 will rise and engage with at least one of the projection / s 12 so as to apply a driving force against the projection / s 12 and cause the rotor shaft 10 to rotate. Each projection 12 can be arranged as a substantially flat plate. The projection / s 12 are formed so as to correspond, at least in part, to the shape and dimensions of the object / s 30. For example, in embodiments where the objects 30 define a substantially spherical shape, each projection 12 can be a substantially planar plate comprising therethrough a substantially circular aperture 14 having a diameter that correspond to the length of a chord that is smaller than the diameter of the spherical object 30, whereby the object 30 can be releasably received within the aperture 14. The interaction between the object 30 captured by a respective one of the projections 12 provide sufficient engagement so as to allow the object 30 to apply an upward force against the projection 12 in order to drive the motion of the projection about the rotor shaft 10. With reference to Figures 6a and 6b, in some forms, the projections 12 can be braced 17 (e.g. a triangle brace). This may assist in preventing hyperextension of the projections 12 beyond a 90 degree angle relative to the belt 16 when engaged by the object 30. The brace 17 is on the non-engaging side as it is rising and is on the lead side when it is disengaged and returning as shown in fig 6 as viewed from the side of the projection 12. In some forms, not shown, each projection can comprise additional curved or slot-like apertures positioned around the outer edge surface of the substantially circular aperture in order to reduce the resistance of the fluid 90 against the projection 12 and allow fluid 90 to flow therethrough. In some forms, referring to Fig. 6b, each projection 12 can comprise one ormore upturned and / or curved edges 77 (i.e. towards the opposite side of the projection having an object in use) around the perimeter of the projection. The upturned and / or curved edge may improve the smoothness of the engagement and disengagement of the object by the projection 12.

[0045] The inlet 22 connects to an airlock comprising a pair of valves 24,25 that are operable to open and / or close via a control system, not shown, in order to release the object / s 30 from a feed tube 40 into the chamber 20 of the drive assembly 100. For example, the control system can comprise one or more mechanical timer and / or an electronic processor. The control system can be programmed manually or via remote access from an external location in order to initiate and cease operation of the drive assembly 100 and / or to adjust the speed with which the object / s 30 are provided into the chamber 20, thereby adjustably controlling the speed of rotation of the rotor shaft 10, and by extension, the kilowatts of electrical energy produced by the electric power generator connected to the drive assembly 100. In a variation, a manually operated mechanical control system can be used to operate the valves (e.g. Fig 7).

[0046] The pair of valves 24,25 are arranged such that the first valve 24 is spaced at a distance from, and lower than, the second valve 25 along the feed tube 40. The first valve 24 can be vertically aligned beneath the higher second valve 25, with the second valve 25 opening into the chamber 20. An airlock compartment 28 defined by the spacing of the lower first valve 24 from the upper second valve 25 of the airlock along the feed tube 40 is adapted such that at least one of the object / s 30 can be stored within the void of the airlock compartment 28 between the first valve 24 and second valve 25 of the airlock prior to entry through the second valve 25 into the chamber 20 via the inlet 22. The control system ensures that the first valve 24 and second valve 25 are not open simultaneously, thereby preventing a free flow of the fluid 90 from the chamber 20. Thus, in use, the first valve 24 is only moved into an open configuration when the second valve 25 has been fully returned to a closed configuration, and the second valve 25 is only moved into an open configuration when the first valve 24 has been fully returned to a closed configuration.

[0047] For example, with reference to Figure 3, an embodiment is shown of the inlet 22" connected to an airlock comprising dual valves 24', 25'. The airlock compartment 28' between the valves 24', 25' has internal dimensions that are sufficient for containing a single sphericalshaped object 30. A length of the airlock compartment 28' between the valves 24', 25' can be substantially equivalent to, or slightly larger than, a diameter of the object 30. A width ofthe airlock compartment 28' can be up to 30% greater than a diameter of the object 30, whereby when the second valve 25' is open the fluid 90 is able to enter the airlock compartment 28', displace the air, and flow around the object 30 in order to displace the object 30 upwards. The width of the first valve 24' can be up to 10% greater than a diameter of the object 30, whilst the width of the second valve 25' can be up to 10% greater than a diameter of the object 30. In some embodiments, the first valve 24' is narrower in width than the second valve 25'.

[0048] The feed tube 40 is formed as an upright U-shaped tubular length of pipe having a lowest point of curvature 42 that locates at a height that is lower than a height of the inlet 22 and the chamber 20. The feed tube 40 comprises a pair of columns 44,46 on either side of the curvature 42 of the U-shape. The inner column 46 locates between the lowest point of curvature 42 and the chamber 20, with the pair of valves 24,25 of the airlock being configured at the end of the inner column 46. The outer column 44 locates on the opposing side of the curvature 42. The inner surface of the feed tube 40 comprises a low friction liner which allows the plurality of objects 30 to easily, and smoothly, slide through the feed tube 40 with minimal frictional resistance. For example, the low friction liner may comprise silicon or Teflon. In another example, with reference to Figs 5a and 5b, a plurality of rollers 60 can be arranged along the underside surface of the feed tube 40 adjacent the lowest point of curvature 42. An in-use upper portion of each of the rollers 60 can protrude through a respective one of the drainage holes 43', which are slot-shaped and sized so as to be longer and wider than the upper portion the roller 60 whereby the roller 60 can spin freely within the aperture of the drainage hole 43'. The rollers 60 can be formed, for example, from a silicon or Teflon material. In use, the rollers 60 may help encourage the objects 30 to roll through the feed tube 40, past the lowest point of curvature 42, towards the first valve 24.

[0049] In use, a plurality of objects 30 can be stored within the feed tube 40, with the quantity of objects 30 stored within the feed tube 40 being sufficient in number, whereby the objects 30 are stacked within the outer column 44 to a height above the lowest point of curvature 42 that is higher than the height of the first valve 24 of the airlock. The gravitational force caused by the cumulative mass of the objects 30 stored within the outer column 44 urges the objects 30 stored within the inner column 46 towards, and through, the open first valve 24 of the airlock in an attempt to achieve a weight equilibirum and balance the weight of the plurality of objects 30 contained within the feed tube 40 on either side of the lowest point of curvature 42.

[0050] Referring to Figure 1A, in order to initiate operation of the drive assembly 100, the control system controls the first valve 24 to move into an open configuration, whilst maintaining the second valve 25 in a closed configuration. In the open configuration, the first valve 24 allows at least the leading object 30' to be loaded into the airlock compartment 28 from the feed tube 40, the leading object 30' being pushed into the airlock compartment 28 by the remainder of the plurality of objects 30 stored within the feed tube 40. As explained above, the leading object 30' is pushed upwards into the airlock compartment 28 by the other objects 30 stored within the feed tube 40 attempting to balance the weight of the objects within the feed tube 40 on either side of the lowest point of curvature 42.

[0051] Referring now to Figure IB, the control system controls the first valve 24 to move into closed configuration, sealing the first valve 24 such that no fluid 90 can pass through the first valve 24. The second valve 25 remains in a closed configuration, with the leading object 30' now stored within the air-filled airlock compartment 28 between the first and second valves 24,25. Where reference is made to air, it is to be understood that this could be either air or a gas such as helium or hydrogen, or a combination thereof that has a density that is lower than the density of the fluid and therefore floats upwards through the fluid.

[0052] Referring now to Figure 1C, the control system controls the second valve 25 to move from the closed configuration to an open configuration, allowing the fluid 90 from the chamber 20 to flood the airlock compartment 28. The first valve 24 remains sealed in closed configuration. As fluid 90 fills the airlock compartment 28, the air bubbles escape and the leading object 30' is elevated through the second valve 25 into the chamber 20 due to the relative low density of the object / s 30 in comparison to the density of the fluid 90, the leading object 30' rising through the fluid 90 until it engages within the aperture 14 of a corresponding leading projection 12' that is arranged to extend to a distal end above the inlet 22 and across the upward floating path of the object / s 30. The leading object 30' imparts a buoyancy force against the leading projection 12', thereby causing the leading projection 12' to initiate rotation about, and relative to, the rotor shaft 10. The object 30 continues to drive the rotation of the corresponding projection 12 until the corresponding projection 12" rotates to an angle at which the buoyancy force of the object 30" dislodges the object 30" from its engagement within the aperture 14 of the projection 12". The substantially planar surface of the projection 12" on either side of the aperture 14 enables the object 30" to be easily released from engagement with the projection 12", and does not require for the projection 12" to be rotated beyond the upper vertical position in order to enable the dislodgement of the object30". The object 30" thus continues to drive the projection 12" with a substantially constant magnitude of force in an upward direction until the projection 12" has rotated sufficiently beyond the path of travel of the object 30" such that the object 30" is released from the holding portion of the aperture 14 and able to slide along the planar outer side surface of the projection 12". The released object 30" then floats freely to the upper surface 92 of the fluid 90 proximal the top 27 of the chamber 20. An outlet 21 is provided substantially in-line with the average level of the upper surface 92 of the fluid 90 in the upper portion of the chamber 20, whereby an object 30 that is released from engagement with a respective projection 12 is directed to float into the outlet 21, and when the following object 30 is subsequently released it pushes the prior object 30" through the outlet 21 so as to exit from the chamber 20. The outlet 21 can be coupled to connect into the outer column 44 of the feed tube 40, thereby providing a return chute towards the inlet 22 through which the object / s 30 can be recycled through the drive assembly 100.

[0053] Referring now to Figure ID, the control system controls the second valve 25 to move from the open configuration back into the closed configuration, with a volume of the fluid 90' filling the airlock compartment 28 between the opposing first and second valves 24,25.

[0054] Referring to Figure IE, once the second valve 25 has been controllably moved to a closed configuration, the control system controls the first valve 24 to again adjust from the closed configuration into an open configuration. As the first valve 24 opens, the fluid 90' contained within the airlock compartment 28 is able to drain downwardly into the inner column 46 of the feed tube 40 towards the lowest point of curvature 42 that comprises one or more drainage holes 43 therethrough to allow the fluid 90' to flow out from the feed tube 40 into a catchment located below 50 the drainage holes 43. The first valve 24 again allows at least the next leading object 30' to be loaded into the void of the airlock compartment 28 from the feed tube 40.

[0055] The method outlined above is then able to be repeated, releasing one or more of the object / s 30 into the chamber 20 so as to continuously drive a rotation of the rotor shaft 10 of the drive assembly 100 until it is desired that operation be ceased, at which point the control system controllably maintains at least the second valve 25 in the closed configuration. As would be appreciated the speed with which the object / s 30 are provided into the chamber 30 can be used to adjustably control the speed of rotation of the rotor shaft 10, and by extension, the kilowatts of electrical energy produced by the electric power generator connected to the drive assembly 100.

[0056] In order to maintain the volume of fluid 90 within the chamber 20 such that the upper surface 92 of the fluid 90 remains above a predetermined minimum fluid level, a control system can be used to monitor the fluid level of the upper surface 92 of the fluid 90, and to controllably provide additional fluid 90 into the chamber when a replenishment of fluid 90 is required. For example, a float valve 52 can be used to detect when the chamber 20 requires an additional volume of the fluid 90 to be supplied. If the level of fluid 90 within the chamber 20 is detected to be below the predetermined minimum fluid level, the float valve will rotate downwards into a position where it mechanically moves into an open configuration thereby allowing an additional volume of the fluid 90 to be supplied into the chamber 20. The additional volume of fluid 90 can be supplied from a mains supply (e.g. where the fluid is water, the water can be provided from the water mains). The supply of fluid 90 into the chamber 20 can be constant, or on-demand when the control system detects a refill is required. Alternatively, in some variations, the fluid 90 collected in the catchment 50 can be continuously recycled back into the chamber 20 using a pump 54, or periodically pumped back into the chamber 20 when the level of fluid 90 is detected to be below the predetermined minimum fluid level for the chamber 20. As would be appreciated by a person skilled in the art, detection of the fluid level can be determined by a variety of mechanical or electronic sensors that communicate with a control system whether additional fluid is required within the chamber. In some variations, the chamber 20 can comprise one or more overflow outlets 97 proximal the top 27 of the chamber 20 along one or more of the side walls of the chamber 20. The overflow outlet / s 97 can locate at a height that is higher than the desired in-use height of the upper surface 92 of the fluid 90 in use, in order to ensure that the majority of the outlet 21 is filled with air, whereby the feed tube 40 remains air- filled such that the object / s 30 are able to freely fall towards the lowest point of curvature 42.

[0057] As would be appreciated by a person skilled in the art, the distance the object 30 is able to rise through the liquid 90 corresponds to the distance the projection 12 is moved, and the angular distance through which the rotor shaft 10 is rotated. It may therefore be preferable to provide a drive assembly 100 having a chamber 20 that is elongate in a vertical orientation. For example, in one embodiment, the chamber of the drive assembly can be arranged within a mine shaft or similar vertically elongate structure or cavity. As a further example, in some embodiments, the drive assembly can arranged at the top of a dam, or similar natural water source. As a further example, in some embodiments, the drive assembly can be configured to be modular and / or portable.

[0058] In embodiments having a vertically elongate chamber 20, the drive assembly 100 can comprises two or more sprockets 11,11' arranged in parallel and being vertically spaced from one another in a substantially co-planar alignment, with at least one of the two or more sprockets 11,11' being fixed to, and aligning collinearly with, a rotor shaft 10 that is coupled to a rotor of an electric power generator (e.g. see Figs la-le). The two or more sprockets 11,11' can be coupled together by a belt 16 that wraps around both of the two or more shafts sprockets 11,11'. The belt 16 is sufficiently tensioned and engaged around the sprockets 11,11' such that a movement of the belt 16 for a distance causes the peripheral surface of each of the two or more shafts sprockets 11,11' to rotate through an equal corresponding angular distance. As would be appreciated by a person skilled in the art, in some variations the belt 16 can be a toothed belt that engages with a correspondingly toothed sprocket 11. The projections 12 are arranged at substantially equally spaced intervals along the belt 16 and each project substantially perpendicularly away from the surface of the belt 16 as the belt 16 is driven to rotate about the sprockets 11,11' in order to drive the rotor shaft 10 and drive assembly 100. In a variation, the belt can be a chain. The vertical height of the belt 16 between the upper shaft 10 and the lower shaft 10' provides sufficient length along which a plurality of projections 12 can be provided. This enables the belt 16 to be driven by a plurality of objects 30, with each object 30 engaging with a respective one of the plurality of projections 12 that are presented in turn as the belt 16 rotates, along the side of the belt 16 that aligns above the inlet 22 within the chamber 20. The cumulative driving force of the plurality of objects 30 can generate a substantially constant upward thrust which the drive assembly 100 can utilise to spin a rotor relative to a stator in order to generate electrical power. In some embodiments, not shown, the rotor shaft is coupled to a flywheel which is adapted to spin and maintain a rotation or the rotor for a period of time after operation of the drive assembly 100 has ceased.

[0059] Referring now to Figures 2A to 2E, a further embodiment of the drive assembly 100' is shown in accordance with the present disclosure. The features of drive assembly 100' are considered to be the same as drive assembly 100 unless specified as being otherwise.

[0060] The chamber 20' of drive assembly 100' includes a dividing wall 93 that extends substantially vertically downwards from proximal the average height of the upper surface 92 of the fluid 90 near the top 27 of the chamber 20'. A lower end of the dividing wall 93 connects to an outer upper surface of a guide elbow 96, effectively acting as a bulkhead that seals and separates the chamber 20' into a plurality of partitions, with a first partition 31containing the rotor shaft 10, one or more projections 12 and a first portion of the fluid 90, and the second partition 32 containing a second portion of the fluid 90. The second portion of the fluid 90 can be in fluid contact with the first portion of the fluid 90 at the upper surface92 of the fluid 90, if the upper surface 92 of the fluid 90 is higher than the upper edge of the dividing wall 93. Alternatively, if the upper surface 92 of the fluid 90 is below the upper edge of the dividing wall 93, the first and second portions of the fluid 90 are retained separately from one another.

[0061] The guide elbow 96 defines an extension of the inlet 22, and provides a stop at which the air 94 received from the airlock can be separated before the object / s 30 are delivered into the chamber 20'. The guide elbow 96 has a first aperture at inlet 22 through which the object enters the guide elbow 96, a second aperture through which the object exits the guide elbow below the projections, and a body that extends therebetween. The second aperture defines a further inlet 22' at a lower portion of the chamber 20', the further inlet 22' being spaced laterally away from the inlet 22 and being located approximately below the projections 12. The tubular body of the guide elbow 96 extends between the lower end of the dividing wall93 and the base surface 26. The body of the guide elbow 96 may extend sideways across the base of the chamber 20' at 90 degrees relative to the inlet 22, or at an angle slightly greater than 90 degrees such that the upper tubular body of the guide elbow 96 provides a gentle upward slope towards the further inlet 22' into the chamber 20'. The upper surface of the body of the guide elbow 96 comprises one or more apertures, for example elongate slots 95, which are adapted to vent the air 94 that enters the guide elbow 96 from the airlock through the upper surface of the guide elbow 96. The one or more apertures are adapted to allow the air 94 that exits from the airlock compartment 28 when the second valve 25 is moved into an open configuration to be released prior to reaching the second aperture of the further inlet 22'. The air bubbles 94 are released into the second partition 32 of the chamber 20' and allowed to float freely to the upper surface 92 of the fluid 90. The one or more apertures are adapted to separate the object / s 30 from the air 94 that enters the fluid 90 within the guide elbow 96 via the inlet 22 such that the object / s 30 and the air 94 are laterally displaced from one another. Thus, the one or more apertures laterally displace the air 94 that enters the inlet 22 from the airlock away from the inlet 22'.

[0062] In use, the guide elbow 96 acts as a through tunnel for the object / s 30 to bypass the second partition 32, adjusting the position of release of the object / s 30 sideways away from the inlet 22. The object / s 30 are guided out of the airlock compartment 28 through the secondvalve 25, upwards through the inlet 22, laterally through the 90 degree (or right angle) bend of the guide elbow 96 and finally out through a further inlet 22' into the first partition 31 of the chamber 20'. Thus, in use, when the second valve 25 is moved into an open configuration, the air 94 that escapes upwards from the airlock compartment 28 is able to be released from the chamber 20' without interacting, or potentially interfering, with the object / s 30 and / or the one or more projections 12 as the rotor shaft 10 is driven to rotate. The object / s 30 are simultaneously released along with the air 94 with the inflow of fluid 90 into the airlock compartment 28 causing the upward displacement of the object / s 30 through the second valve 25, the inlet 22, the guide elbow 96, and the further inlet 22' and into the first partition 31 of the chamber 20'. The released air 94 can take the form of a single air pocket or a plurality of air bubbles. The guide elbow 96 extends into the first partition 31 of the chamber 20' for a distance such that when the object / s 30 are released into the first partition 31 via the further inlet 22', the object / s 30 will rise upwards and engage with one of the projection / s 12 as they rise through the fluid 90 so as to drive the rotor shaft 10. By separating the air 94 from the object / s 30, and releasing the air 94 away from the path of travel of the object / s 30, the object / s 30 are able to drive the rotor shaft 10 with reduced turbulence in the fluid 90 along the path of travel of the object / s 30 / . Highly turbulent flow could in some instances disrupt or dislodge the object / s 30 from the one or more projections 12. This may also improve the repeatability and precision with which the object / s 30 can engage with the one or more projections 12 upon entry into the first partition 31, without air bubbles or pockets of air generating chaotic fluid flow around the object / s 30.

[0063] The guide elbow 96 can facilitate the lateral displacement of the object / s 30 such that the path of travel of the object / s is laterally displaced from a path of travel of the released air 94. In this manner, the guide elbow 96 can ensure that the object / s are funnelled sideways away from the path of the air 94 before being released into the chamber 20. The position at which the object / s 30 depart from the inlet 22' of the guide elbow 96 shifts the object / s 30 away from the position of the one or more apertures, whereby the fluid 90 through which the object / s 30 travel upwards through the chamber 20 is less turbulent than the fluid 90 in which the air 94 is floating upwards towards the upper surface 92 of the fluid 90. This may advantageously improve the engagement of the object / s 30 with the projections 12, and enable the object / s 30 to continue to drive the rotor shaft 10 even after being released from the holding portion of the aperture 14.

[0064] In a further example, referring to Figures 4A to 4D, each of the first and secondvalves 24", 25" can comprise a substantially planar plate 62 that is configured to slide linearly across the feed tube 40 adjacent the inlet 22 between an open and closed configuration. The leading edge 64 of each plate 62 can be formed to have a small radius equal to half the thickness of the plate 62. The lower plate 62 can have a reverse taper 65 65 that has a very small radius on the lead front edge of the said reverse taper 65 and that extends across at least a part of the width of the plate 62 and along the underside of the lower plate 62 from the leading edge 64 towards a centred position of the plate 62, where the centred position is located at a distance away from the leading edge of the plate 62 that is equivalent to approximately half the diameter of an object 30. The small radius of the leading edge 64 and / or the reverse taper 65 may assist the plates 62 when sliding between two adjacent objects 30, with the lower trailing object 30"" being gently prised away from the upper leading object 30"' as the plate 62 is slid therebetween. The lower trailing object 30"" can be gently pushed back down within the feed tube 40 by the small radius of the leading edge 64 and the reverse taper 65 for a distance equal to the thickness of plate 62. In some embodiments, the plates 62 can be lined with a low friction liner to further assist with the sliding insertion between objects 30.

[0065] In use, operation of the plate-like valves 24", 25", is similar to that describe above. The valves 24", 25" are electrically or manually controlled via a control system to move between the open and closed configuration. For example, an electronic control system may comprise a plurality of linear actuators that are arranged to drive and retract the plates 62, with the timing synchronised to ensure that only one of the valves 24", 25" is open at any given time. In a further example, manual driven mechanical levers 68 can be arranged to enable an operator to open and close the valves 24", 25" (e.g. Figure 7).

[0066] In order to initiate operation of the drive assembly 100, the first valve 24" is moved into an open configuration, whilst maintaining the second valve 25" in a closed configuration, allowing the leading object 30"' to be loaded into the airlock compartment 28" from the feed tube 40. The leading object 30'" is pushed into the airlock compartment 28" by the gravitational force applied on the leading object 30'" by the other objects 30 stored within the feed tube 40 as they attempt to balance the weight of the objects 30 within the feed tube 40 on either side of the lowest point of curvature 42. As the object enters the airlock compartment 28", any fluid 90 contained within the airlock compartment 28" is allowed to drain down the feed tube 40 towards the drainage holes 43.

[0067] With reference to Figure 4A the first valve 24 is moved into a closed configurationand sealed such that no fluid 90 can pass through the first valve 24. The second valve 25 remains in a closed configuration, with the leading object 30"' stored within the air-filled airlock compartment 28" between the first and second valves 24,25. With reference to Figure 4B, the second valve 25 is then controlled to move from the closed configuration to an open configuration, allowing the fluid 90 from the chamber 20 to flood the airlock compartment 28. The first valve 24 remains sealed in closed configuration. As fluid 90 fills the airlock compartment, the air bubbles escape upwards and the leading object 30"' is elevated through the second valve 25" and the inlet 22 into the guide elbow 96 and chamber 20' due to the relative low density of the object 30'" in comparison to the density of the fluid 90. With reference to Figure 4C, the second valve 25" is then moved from the open configuration back into the closed configuration, with a volume of the fluid 90 remaining inside the airlock compartment 28" between the opposing first and second valves 24", 25". With reference to Figure 4D, once the second valve 25" has been moved to a closed configuration, the first valve 24" is slidably moved towards an open configuration. As the first valve 24" opens, the fluid 90 contained within the airlock compartment 28" is able to drain downwardly into the feed tube 40 towards the one or more drainage holes 43, and the next leading object 30"" is loaded into the void of the airlock compartment 28" from the feed tube 40. The steps of the method are able to be repeated, continuously feeding one or more object / s 30 into the chamber 20 whereby the rotor shaft 10 of the drive assembly 100 is continuously driven to rotate until it is desired that operation be ceased.

[0068] In some embodiments, a clutch brake mechanism can be attached to at least one of the sprockets 11 in order to assist an operator in controlling the speed of rotation of the rotor shaft / s 10. The clutch brake mechanism can comprise a brake pad 72 that is arranged to act on the outer perimeter of a flywheel 70, with the frictional force of the brake pad 72 against the flywheel 70 being adjustable so as to adjustably control the magnitude of the braking. For example, the brake mechanism can be applied to slow and / or stop the a rotation of the rotor shaft 10 of the drive assembly 100, or released to initiate or allow for an increase in the speed of rotation. The speed of rotation of the rotor shaft 10 of the drive assembly 100 is also controllable by adjusting the speed with which the object / s 30 are fed into the chamber 20.

[0069] Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure. For example, in a further variation, not shown, a single chamber 20, without a plurality of partitions, can comprise a guide elbow96 as described above.

[0070] In the foregoing description of preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as "front" and "rear", "inner" and "outer", "above", "below", "upper" and "lower" and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0071] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0072] In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of’. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.

[0073] In addition, the foregoing describes only some embodiments of the invention(s), and alterations, modifications, additions and / or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive.

[0074] Furthermore, invention(s) have been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention(s). Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Claims

CLAIMS:

1. A drive assembly for an electric power generator comprising a rotor shaft that is at least partially submersed in a fluid, the rotor shaft having one or more projections arranged to extend away from the rotor shaft peripherally therearound, the projections being adapted to engage with an object having a density lower than a density of the fluid, whereby a buoyant force of the object rising through the fluid drives the projections to rotate the rotor shaft, wherein the rotor shaft locates at least partially within a chamber containing the fluid, the chamber having the inlet at a lower portion thereof through which the object is able to enter the chamber below the projections and an airlock that connects to the inlet from which the object is released into the inlet, and wherein the inlet is adapted to separate air received from the airlock before delivering the object into the chamber.

2. The drive assembly as claimed in claim 1, wherein the inlet comprises a first aperture through which the object enters the inlet, a second aperture through which the object is delivered into the chamber, and a body that extends therebetween, the body having one or more openings through an upper surface thereof that are adapted to vent the air that enters the inlet from the airlock.

3. The drive assembly as claimed in claim 2, wherein the one or more openings laterally displace the air from the second aperture of the inlet.

4. The drive assembly as claimed in any one of the preceding claims, wherein the airlock comprises a lower first valve and a higher second valve, a space between the first and second valves defining an airlock compartment adapted to store the object prior to entry into the chamber.

5. The drive assembly as claimed in claim 4, wherein the first and second valves being configured such that when the first valve is open the second valve is closed, and when the second valve is open the first valve is closed.

6. The drive assembly as claimed in claim 5, wherein, when the first valve is open the fluid is allowed to drain from the airlock compartment and the object is able to be loaded therein.

7. The drive assembly as claimed in claim 5 or 6, wherein, when the second valve is open the fluid from the chamber is allowed to fill the airlock compartment, and the object within the airlock compartment is released to rise through the second valve and into the chamber.

8. The drive assembly as claimed in any one of claims 4 to 7, wherein the first and second valves are operable to open and / or close via a control system.

9. The drive assembly as claimed in claim 8, wherein the control system comprises a mechanical timer and / or an electronic processor.

10. The drive assembly as claimed in any one of the preceding claims, wherein the chamber further comprises an outlet at an upper portion thereof through which the object is able to exit from the chamber.

11. The drive assembly as claimed in claim 10, wherein the outlet is connected to the inlet via a tube that facilitates the return of the object exiting the outlet to the inlet.

12. The drive assembly as claimed in claim 11, wherein the tube comprises a low friction liner therein.

13. The drive assembly as claimed in claims 11 or 12, when dependent on claim 7, wherein the tube comprises a drainage hole through which the fluid drained from the airlock compartment is able to flow from the tube.

14. The drive assembly as claimed in claim 13, wherein the fluid flowing through the drainage hole is stored in a catchment and / or recycled into the chamber.

15. The drive assembly as claimed in any one of the preceding claims, wherein the fluid in the chamber can be replenished from a mains supply.

16. The drive assembly as claimed in any one of claims 14 or 15, wherein the assembly comprises a control system that is configured to detect when the chamber requires an additional volume of the fluid to be supplied, and to supply the additional volume of the fluid.

17. The drive assembly as claimed in any claims 16, wherein the control system comprises a float valve.

18. The drive assembly as claimed in any one of the preceding claims, wherein the assembly comprises a plurality of the object / s.

19. The drive assembly as claimed in any one of the preceding claims, wherein the object is spherical.

20. The drive assembly as claimed in any one of the preceding claims, wherein the object contains a filling comprising air.

21. The drive assembly as claimed in any one of the preceding claims, wherein the object contains a filling comprising polystyrene, and has an external coating comprising polyurethane.

22. The drive assembly as claimed in any one of the preceding claims, wherein the fluid is liquid.

23. The drive assembly as claimed in any one of the preceding claims, wherein the projections correspond, at least in part, to the shape and dimensions of the object, so as to releasably receive and engage with the object.

24. The drive assembly as claimed in claim 23, wherein the projections comprise an aperture adapted to releasably receive and engage with the object.

25. The drive assembly as claimed in any one of the preceding claims, wherein the drive assembly comprises a second shaft in vertically spaced relation to the rotor shaft, the rotorshaft and second shaft being coupled together by a belt having the projections arranged to extend substantially perpendicularly away therefrom.

26. The drive assembly as claimed in any one of the preceding claims, wherein the chamber is elongate in a vertical direction.

27. The drive assembly as claimed in any one of the preceding claims, wherein the chamber comprises a dividing wall that separates a first portion of the chamber having the rotor shaft and a second portion of the chamber above which the inlet delivers the object into the chamber.

28. The drive assembly as claimed in claim 27, wherein the inlet comprises a guide elbow, the guide elbow being adapted to guide the object through the second portion of the chamber and into the first portion of the chamber.

29. The drive assembly as claimed in claim 28, wherein the guide elbow comprises one or more apertures adapted to separate and vent the air received from the airlock away from the object and into the second portion of the chamber before the object enters the first portion of the chamber.

30. An electrical power system comprising the drive assembly as claimed in any one of the preceding claims; and a rotor and a stator, the rotor being coupled to the rotor shaft and arranged to rotate relative to the stator so as to generate electrical power.

31. The electrical power system as claimed in claim 30, wherein the rotor shaft is coupled to a flywheel.

32. A method of driving a rotor shaft for an electric power generator, the rotor shaft being at least partially submersed in a fluid and having one or more projections arranged to extend away from the rotor shaft peripherally therearound, the rotor shaft being located at least partially within a chamber containing the fluid, the chamber having an inlet at a lower portion thereof through which an object is able to enter the chamber below the projectionsand an airlock that connects to the inlet from which the object is released into the inlet, the method comprising releasing an object into the fluid via the inlet, the inlet being adapted to separate air received from the airlock before delivering the object into the chamber, the object having a density lower than a density of the fluid; and engaging a respective one of the projections with the object whereby a buoyant force of the object rising through the fluid drives the projection to rotate the rotor shaft.

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