generator

Abstract

A generator 1 comprising a rotor 7 and a stator 9. The rotor comprises a set of one or more helical flights 47b upon which fluid acts to turn the rotor about a rotation axis. The set of one or more helical flights comprises a periphery via which elements are driven to rotate about a stator. The stator magnetically co-operates with the elements 21, 23 to produce electricity. A rotor portion is a portion of the rotor, bounded (by two notional planes mutually parallel and each perpendicular to the rotation axis) and comprising one or more flight portions, of the one or more helical flights, helically turning through one or more helical-turn angles summing to a full turn. An outer circle 47a' has a radius and is a circle through which an outermost portion of the one or more flight portions turns. When the rotor portion is notionally viewed in a rotation axis direction, a notional circular area NC concentric to, and having a radius half the radius of, the outer circle is at least 50% closed to direct axial flow.

Description

[0001] P1959PCAU

[0002] 1

[0003] GENERATOR

[0004] FIELD

[0005] The invention relates to generators. Preferred embodiments relate to generators, assemblies, and in particular to impeller generators for use inline in a pipeline.

[0006] BACKGROUND

[0007] Figure 1 schematically illustrates a pressure reducing valve PRV in which a valve element VE is captured between pair of springs S and diaphragm D such that pressure of the downstream side DS of the valve drives the valve element towards its closed position. In this way, the valve closes in response to rising pressure downstream of the system to continuously throttle the fluid to limit pressure on the downstream side DS.

[0008] Pressure reducing valves are commonly used to protect domestic appliances from mains pressure and in various industrial applications.

[0009] The present inventors have recognised that typical pressure reducing valves are wasteful in that fluid power (corresponding to the product of the pressure drop and the flow rate) is viscously dissipated. In turn, new methods and apparatus associated with generating electrical power have been developed. Various embodiments of these methods and apparatus may find application far removed from pressure reducing valves.

[0010] Conventional generator assemblies that use the force of a flow of fluid through a pipeline to generate an electrical current typically include impeller shafts. The present inventors have recognised that the inclusion of a shaft, and its associated support infrastructure significantly, has drawbacks. It can degrade the free-flowing property of the pipeline through that section. Further, typical generators require gearing and associated gear couplings that are expensive to manufacture, require P1959PCAU

[0011] 2 maintenance, and require lubrication. All of these features reduce the efficiency of the generator and reduce the quality of the flow through the pipeline.

[0012] US patent publication no. 2015 / 0145257 A1 ‘Energy generating apparatus for gas or liquid flow conditions’ discloses shaftless generators comprising rotors comprising internal bores through which fluid flows. An illustrated variant comprises a tapered bore with helical grooves. Another illustrated variant comprises a straight bore lined with a helical flight.

[0013] The invention aims to provide improvements, or at least alternatives, in and for generating.

[0014] SUMMARY

[0015] One aspect of the invention provides a generator comprising a rotor and a stator; wherein the rotor comprises a set of one or more helical flights upon which fluid acts to turn the rotor about a rotation axis; the set of one or more helical flights comprises a periphery via which elements are driven to rotate about a stator; the stator magnetically co-operates with the elements to produce electricity; a rotor portion is a portion of the rotor and bounded by two notional planes mutually parallel and each perpendicular to the rotation axis; and comprising one or more flight portions, of the one or more helical flights, helically turning through one or more helical-turn angles summing to a full turn; P1959PCAU

[0016] 3 an outer circle has a radius and is a circle through which an outermost portion of the one or more flight portions turns; and when the rotor portion is notionally viewed in a rotation axis direction, a notional circular area concentric to, and having a radius half the radius of, the outer circle is at least 50%, e.g. at least 75%, closed to direct axial flow.

[0017] Preferably, an innermost portion of the one or more flight portions turns at a radius not more than 20%, e.g. not more than 10%, of the radius of the outer circle. Most preferably, when the rotor portion is notionally viewed in a rotation axis direction, the outer circle is at least 90%, e.g. at least 95%, closed to direct axial flow.

[0018] In preferred embodiments, each of the one or more helical flights comprises at least 0.5 turns, e.g. at least 1 .0 turns, or more preferably at least 2.0 turns.

[0019] The set of one or more helical flights is preferably a plural-flight set comprising plural of the flights axially aligned and angularly offset with respect to each other, e.g. a four-flight set comprising four of the flights axially aligned and angularly offset with respect to each other. The flights are preferably evenly angularly spaced around the rotation axis.

[0020] Optionally, each of the one or more helical flights has a pitch in the range of 100% to 300% (inclusive), or preferably in the range of 150% to 250% (inclusive), of the radius of the outer circle. Preferably, adjacent convolutions of the one or more helical flights are axially separated by distance in the range of 25% to 75% (inclusive), or more preferably in the range of 40% to 60% (inclusive), of the radius of the outer circle.

[0021] The rotor comprises a housing about the periphery and carrying the elements, in which case the set of one or more flights may be welded to the housing. Alternatively, the rotor may comprise two or more rotor-segments that are substantially identical to each other; P1959PCAU

[0022] 4 are axially spaced with respect to each other; and each define a portion of the housing and of the set of one or more helical flights.

[0023] Optionally, each adjacent two segments of the two or more rotor-segments comprises features interlocking to mutually align the adjacent two segments.

[0024] Another aspect of the invention provides a system comprising a generator; and downstream of the generator, a valve that closes in response to rising pressure downstream of the system.

[0025] Another aspect of the invention provides a method of manufacturing a rotor for a generator; the method comprising welding a set of one or more helical flights into an interior of a cylindrical housing.

[0026] Optionally, the set of one or more helical flights is a plural-flight set comprising plural of the flights axially aligned and angularly offset with respect to each other, in which case the method may comprise relatively-inserting and welding in place one of the plural flights, then relatively-inserting and welding in place another of the plural flights.

[0027] The method may comprise arranging a respective two or more helical flightportions end-to-end to form each of the one or more helical flights.

[0028] The welding comprises welding via openings through a wall of the housing, in which case the method preferably comprises closing the openings. P1959PCAU

[0029] 5

[0030] Another aspect of the invention provides a rotor-segment for a generator comprising a ring; and within the ring a set of one or more flight portions; wherein the rotor-segment is combinable with identical rotor-segments to form a rotor comprising a set of one or more helical flights upon which fluid acts to turn the rotor; and a housing about a periphery, of the set of one or more helical flights, via which drive is transmitted to the housing.

[0031] Another aspect of the invention provides a method of starting a generator; wherein the generator comprises a stator and a rotor; and the method comprises supplying electricity to the stator to rotationally drive the rotor.

[0032] Another aspect of the invention provides an electrical generator assembly adapted for use inline in a pipeline wherein said electrical generator assembly includes:

[0033] - a housing assembly, and

[0034] - an impeller, and

[0035] - a rotor containing a plurality of magnet pairs, and

[0036] - a stator assembly, and

[0037] - bearings, and P1959PCAU

[0038] 6

[0039] - electrical contacts.

[0040] The housing assembly is adapted to allow a flow of fluid that is flowing inside the pipeline network to flow directly through the generator assembly. A substantial portion of the flow in the pipeline impinges upon the impeller, forcing it to turn. The turning of the impeller causes the rotor to rotate around the centre axis of the impeller and interact with the stator to generate an electrical current that is then passed to the electrical contacts. The bearings support and reduce friction on the impeller.

[0041] Optionally, the electrical generator assembly comprises

[0042] - a first flange and gasket, and

[0043] - a second flange and gasket, wherein the first flange and gasket are adapted to be interconnected to an adjacent flange on the pipeline into which the electrical generator assembly is to be installed, and wherein the second flange and gasket, located at the opposite end to the first flange and gasket, are adapted to be interconnected to an adjacent flange on the pipeline thereby making the electrical generator assembly inline with the pipeline.

[0044] Preferably, a portion of the flow is directed around the impeller and is adapted to lubricate the bearings.

[0045] Preferably, the portion of the flow that is directed around the impeller is also adapted to cool the stator assembly.

[0046] Preferably, the housing assembly includes bypass channelling that directs the portion of the flow.

[0047] Optionally, the housing assembly is in predominately two parts that are releasably fastened together upon a gasket, thereby allowing the electrical generator P1959PCAU

[0048] 7 assembly housing to be disassembled so that the inner parts may be serviced or replaced as necessary.

[0049] Preferably, the magnets are permanent magnets, thereby eliminating the need to use an excitor coil.

[0050] Preferably, the impeller includes no shaft to thereby maximise the efficiency of the impeller and minimise the disruption of the flow through the pipeline.

[0051] Preferably, the assembly does not include any gearing or associated gear couplings to further improve the overall efficiency of the assembly.

[0052] Preferably, the stator is inside a stator housing and a coil made from a filament of conducting material, such as copper wire, is housed in the stator housing and the interstitial spaces around the coil inside the housing are filled with an insulating resin.

[0053] Preferably, the stator is integrated into the outer peripheral surface of the impeller, and wherein the stator holds permanent magnet pairs and therefore no excitation coil is required.

[0054] Preferably, the bearing is assembled onto the outer peripheral surface of the impeller, and therefore no seal is required for the bearings and since the bearings are lubricated from the portion of the flow directed around the impeller, no oilbased lubricant is required.

[0055] Alternatively, in a second preferred form of the present invention, the impeller includes a plurality of interlocking pieces that are each keyed to lock with an adjacent piece so that as each piece is locked into place, the assembly thereby produced forms the shape of an impeller that runs substantially along the length of the housing assembly. P1959PCAU

[0056] 8

[0057] Preferably, a steel cylinder and magnet assembly is a magnetically conductive steel cylinder where the outer side wall of the cylinder includes a plurality of shaped, equispaced, longitudinally shaped magnets.

[0058] Preferably, the steel cylinder is interference fitted with the impeller or impeller assembly.

[0059] Preferably, the rotor assembly is also cylindrically shaped and contains the steel cylinder and the impeller assembly, and the bearings.

[0060] Preferably, the stator is subsequently resin-filled with an insulating resin after assembly.

[0061] BRIEF DESCRIPTION OF DRAWINGS

[0062] The figures illustrate various features by way example only.

[0063] Figure 1 is a cross-section view of a pressure reducing valve.

[0064] Figure 2 is a perspective view of a generator.

[0065] Figure 3 is an exploded view of the generator.

[0066] Figure 4 is a perspective view of select portions of a rotor of the generator.

[0067] Figure 5 is a perspective view of the rotor of the generator fitted with bearings.

[0068] Figure 6 is a perspective view of the stator assembly of the generator.

[0069] Figure 7 is an exploded view of a second generator.

[0070] Figure 8 is a perspective view of a rotor segment of the second generator.

[0071] Figure 9 is a perspective view of a rotor sub-assembly of the second generator. P1959PCAU

[0072] 9

[0073] Figure 10 is a perspective view of a cylinder and magnet assembly of the second generator.

[0074] Figure 11 is a perspective view of the rotor of the generator fitted with bearings of the second generator.

[0075] Figure 12 is an end view of the rotor of the generator fitted with bearings of the second generator.

[0076] Figure 13 is a perspective view of the stator of the second generator before being filled with insulative resin.

[0077] Figure 14 is a perspective view of the stator of the second generator after being filled with insulative resin.

[0078] Figure 15 is another exploded view of the second generator.

[0079] Figure 16 is cross-section view of the generator.

[0080] Figure 17 is a perspective view of a pressure reducing system.

[0081] Figures 18a to 18k are parti ally-cutaway views illustrating the assembly of an alternate impeller.

[0082] Figure 19a to 19k are cross section views corresponding to Figures 18a to 18k.

[0083] Figure 20 is a cross-section view of a third generator comprising the impeller of Figures 18k and 19k.

[0084] DESCRIPTION OF EMBODIMENTS

[0085] The inline electrical generator assembly 1 includes a housing that is made up of two parts 5 and 11 respectively. These two parts are adapted to be releasably fastened together, and the housing encloses the working parts of the generator 1. P1959PCAU

[0086] 10

[0087] The first part 5 includes a first flange 3 and the second part 11 includes a second flange 13. Flanges 3 and 13 are adapted to connect to adjacent flanged in respective end is of a pipeline so that the generator assembly is inline with the flow through the pipeline. Other variants are possible, e.g. a flangeless variant might be welded into a pipeline. In yet another variant, part 5 might be integral to a wall of a water tank.

[0088] The generator assembly 1 includes an ‘impeller and rotor assembly’ or simply ‘rotor’ 7 and a stator 9.

[0089] Turning to Figure 4, we can see more detail of the ‘set of flights’ or ‘impeller’ 15 of the rotor 7. In this preferred embodiment, the impeller 15 is helical. More specifically, the impeller 15 a single integral body comprising four helical flights axially aligned and offset by 90° with respect to each other. Each of the helical flights extends for one full helical turn. As used herein, ‘integral formation’ refers to formation from a single continuous body of material whereby two bodies may be integrated by welding but not by typical mechanical fastening.

[0090] The arrow indicates the direction of flow, and in this example the impeller 15 rotates clockwise. Note that the entire body rotates. The rotor comprises a plurality of fixed magnet pairs 21 , 23 (Figure 5) that are not shown in Figure 4. The fixed magnet pairs are mounted between rotor mounts 19. As the rotor turns, the magnets produce a rotating magnetic field that induces electrical current in the stator 9. In this way, the stator magnetically cooperates with the magnets to produce electricity.

[0091] Magnets are a preferred form of element with which the stator magnetically cooperates to produce electricity. Alternatively, the generator may be an induction generator, e.g. the elements may be the bars of a squirrel cage and with which the stator magnetically co-operates to produce electricity. Preferably, the rotor 7 comprises the elements, although conceivably a mechanical transmission (e.g. belt drive) may transmit drive from the rotor 7 to a remote load, e.g. to rotate the elements about a second rotation axis offset from the rotation axis about which the P1959PCAU

[0092] 11 rotor 7 rotates. Preferably, the elements rotate about the inside of the stator, although external rotors and axial-flux rotors are also possible.

[0093] Bearing surfaces 17 engage with a respective outer circumferential bearing 35 (Figure 4). In this view, we can see the fixed magnet pairs 21 and 23 are mounted by the mounts 19. The bearings 35 support the impeller and rotor assembly within the housing. As fluid flows through the pipeline, the fluid impinges upon the impeller 15 and forces the entire impeller and rotor assembly to rotate about the bearings 35. Housed within the stator housing 25 is a coil 27 of conductive filament, such as copper wire. The interstitial space within the housing around the coil 27 is an insulating resin 29. The stator assembly includes a stator housing 25 that includes a plurality of stator mounts 31 (Figure 6).

[0094] Figures 7 to 15 illustrate a second generator 39. Figure 16 shows the second generator 39 as part of an installed pressure reducing system. Within these figures, parts corresponding to parts discussed in respect of the earlier figures are assigned corresponding reference numbers.

[0095] The installed system comprises an inlet hydraulic pipe 37 supplying a flow of fluid to the generator assembly 39 and an outlet pipe 41. The unique construction of the impeller assembly within the generator assembly 39 has no centre shaft, and thereby minimises the disruption to the flow through the generator assembly 39, thereby minimising the flowrate and change in water pressure across the generator assembly 39. In addition to the generator assembly, the invention includes an air driven shut off valve 43 and an inverter and control unit 45.

[0096] The generator assembly 39 comprises bearings 35 located at each end of the impeller assembly 15 that is made up by a plurality of impeller segments 47. The cylinder and magnet assembly 49 is cylindrically shaped and is interference-fitted over the impeller assembly 15. The cylinder and magnet assembly 49 includes a plurality of elongate shaped magnets 41 arranged in an equispaced arrangement around the outer periphery. As the flow of fluid through the generator impinges upon the impeller assembly 15, the steel cylinder and magnet assembly 49 is P1959PCAU

[0097] 12 adapted to rotate as well. The silicon steel sheet and coil stator 53 is also cylindrically shaped and is sized so that the cylinder and magnet assembly 49 is able to rotate within it. The entire rotor and stator assembly is fitted into a housing assembly.

[0098] Each impeller segment 47 is an example of a rotor-segment and is keyed 55 so that when a plurality of segments is placed in contact together, the key lock ensures that each impeller segment 47 is in the correct orientation relative to its neighbouring segments so that when the impeller is fully assembled, the impeller has the correct shape to minimise disruption to fluid flow through the impeller.

[0099] The cylinder and magnet assembly 49 is cylindrically shaped and includes a plurality of equispaced magnets 51 around the outer periphery. The cylinder and magnet assembly 49 is interference fitted to the impeller assembly 15 to form to rotor 7. Bearings 35 are added to form the sub-assembly 7, 35 of Figure 11 .

[0100] Figures 13 and 14 show the stator assembly 53 including the conductor coil 27 that extends around the inner periphery. As a final step in the stator 53 assembly, the conductor coil 27 is protected by an insulative polymer resin 29.

[0101] Turning to Figure 16, we are shown a cut-away side view showing most of the flow passing through the impeller portion while a small portion 33 bypasses the interior of the impeller and instead travels through bearings 35 and a small annular gap outside the rotor 15. This flow diverted through the housing and around the impeller may be adapted to lubricate the bearings 35 and / or cool the stator assembly. Water lubrication removes the need to use another form of lubricant and a retaining system to keep the lubricant from coming into contact with the fluid flow.

[0102] The impeller 15 of Figure 9 comprises a train, of eight impeller segments 47, running in the axial direction. The segments 47 are substantially identical to each other. The ends of the train of eight segments 47 are capped by end rings 48 that define seats for the bearings 35. Preferably, components 47, 48 are moulded (e.g. P1959PCAU

[0103] 13 injection moulded) although other convenient modes of manufacture are possible. In the illustrated example, the segments 47 are marked with die cavity numbers.

[0104] Each segment 47 comprises an outer ring 47a (Figure 8) and four flight portions 47b projecting inwards from the inside of the ring 47a almost to the centre of the segment. Each flight portion 47b defines a quarter helical turn of a helical flight and the flight portions 47b are equally spread around at the interior of the ring 47a.

[0105] As best illustrated in Figure 16, when the eight segments 47 are brought together, the rings 47a sit in register with each other to define a cylindrical housing. The flight portions 47b sit in register with each other inside the housing to define four helical flights each comprising two full helical turns over the length of the impeller 15. This modular construction affords great flexibility and makes it cost-effective to adjust the length of the impeller to best suit the available pressure and flow. The bearings 35 rotatably support the rotor 7 within the stator 53. That stator is capped by end pieces 5 which capture the outer races of the bearings 35 and define mounting flanges 3, 13.

[0106] As best illustrated in Figure 12, interior 47a’ of the wall 47a corresponds to an outer circle about which an outermost portion of the flight portions 47b turn. The illustrated notional circle NC has a radius half of the radius of the outer circle. When the rotor is viewed end on, the rotor is largely closed to direct axial flow; the small opening 47b’ at the innermost extent of the light portions 47B is the only portion open to direct axial flow. In this way, the flights essentially fully span the internal flow path to more efficiently extract fluid power when there is a large pressure differential and low flow rate.

[0107] In some variants, an outermost flight portion of the impeller turns through a radius of less than 300 mm, e.g. down to 15mm. In other variants, that radius is at least 300 mm, e.g. up to 2000 mm. P1959PCAU

[0108] 14

[0109] Other variants may do without the opening 47b’. In one variant, the open 47b’ is occupied by a shaft to block direct axial. Since the flights transmit drive outwardly via their outer peripheries, the shaft does not need to transmit power and thus may be narrow, hydrodynamically formed, free of supporting and power-transmitting infrastructure (such as bearings and gears, belts or chains) and as such may be hydrodynamically efficient.

[0110] In a preferred implementation, the generator 39 forms part of a pressure reducing system comprising a pressure reducing valve downstream of the generator. According to a preferred implementation, the system is configured to minimise the pressure drop across the PRV, so as to minimise viscous losses. In this way, the system can efficiently recover fluid power whilst fluid is flowing and, on the other hand, downstream equipment is protected against overpressure when the flow is stopped (e.g. when a downstream faucet is closed). In a rudimentary implementation, the valve downstream of the generator may be a mechanical valve in which the motive force to move the movable element(s) of the valve is provided by the fluid pressure itself. In other implementations, the valve may be an electromechanical valve. By way of example, the valve 43 might be moved to the downstream side of the generator 39 and controlled in response to a pressure sensor downstream of the valve.

[0111] The present inventors have recognised that static friction within the bearings, the inertia of the rotor and ‘cogging torque’ impede, and in some cases prevent, the stationary rotor turning when exposed to flow. Accordingly, the inventors propose to energise the stator to help overcome these initial impediments. In the context of the system comprising an electromechanical valve controlled in response to a downstream pressure sensor, this start up procedure may be initiated in response to a combination of pressure data and valve-position data indicative of flow above a requisite minimum. There are other ways in which the turbine may be started in response to a threshold flowrate being reached, e.g. a dedicated flowrate sensor may be installed. This advantageous method of turbine-starting may be applied to turbines other than those that detailed herein. P1959PCAU

[0112] 15

[0113] Preferred variants of the generator incorporate a control system including sensors. Preferably, the sensors sense voltage, current, pressure, flow rate and RPM.

[0114] Other sensors could be added.

[0115] Figures 18a to 19k illustrate another method for forming a four-flight helical impeller. The method commences with a cylindrical housing 147a. In Figures 18a to 18k, the top half of the housing is cut away to illustrate the fitment of the flights 147bi to 147b4.

[0116] The wall of the housing 147a is penetrated by four helical arrays of openings 148.

[0117] The flight 147bi is a single integral piece about 2 mm thick and centred on a surface defined by x = r cos (z / b) y = r cos (z / b) wherein x, y and z are co-ordinates; r is the radius and has a range of values; and b is a constant equal to the pitch 2TT.

[0118] In this example, r ranges from a small minimum value related to the material thickness to suit assembly, up to a value selected for a close fit within the interior of the housing 147a. In this example, the flight 147bi is 3D printed although other modes of construction are possible. Likewise, other helical shapes are possible, e.g. whilst the illustrated straight helixes are convenient to manufacture and lend themselves to adjusting the rotor length to suit flow conditions, a converging conical helix may have performance advantages in certain circumstances.

[0119] The flight 147bi is relatively-inserted into the housing 147a, e.g. the flight 147bi is inserted or is held stationary whilst the housing 147a is manoeuvred onto the flight P1959PCAU

[0120] 16

[0121] 147bi. Once the flight 147bi is in register with a helical set of holes 148, the flight 147bi is welded in place via those holes.

[0122] Further flights 147b2 to 147b4 are then taken in turn and each first screwed into place and then welded in place. Figure 18d illustrates the second flight 147b2 being screwed into place. Figures 18k and 19k illustrate a complete weldment 149 that may then be machined to restore its cylindrical exterior. The holes 148 are closed by the welding and by the subsequent addition of a magnet carrying sleeve akin to the sleeve 49 to form rotor 149’.

[0123] The flight 147bs comprises interlocking features in the form of key 155a and keyway 155b by which axially adjacent flight members can be mutually engaged and aligned to create longer flights.

[0124] The flight 147ai has an outer radius R at a pitch P about double the radius R (Figure 19a). The final positions of the helical flights are axially aligned and angularly offset with each other so they are interleaved in a manner akin to the threads of a double thread being interleaved with respect to each other and so as to result in an axial separation S (Figure 19k) between adjacent convolutions of about half of the outer radius R.

[0125] Figure 20 illustrates a generator 101 comprising rotor 149’ rotationally carried by angled bearings 135a and thrust bearing 135b. The ends of a tubular stator housing are capped by end pieces carrying lip seals 151 that sealingly engage the housing 147a of the rotor 149’. Employing seals, such as the lip seals, can negate the need to pot the stator windings in resin.

[0126] A set of stator vanes 153 sit upstream of the rotor to induce a helical flow and enhance energy recovery. Contra-rotating generator rotors might be arranged in series to similar effect.

[0127] Preferred variants are suited to an upstream pressure of 350 kPa or more and can be configured (e.g. by selecting the length of the impeller) to suit flow rates in the P1959PCAU

[0128] 17 range of 10 to 1000 litres / second (inclusive) and reduce the pressure by more than 300 kPa or more down to selected value of 50 kPa or more.

[0129] Potential applications included installations in water pressure management systems of high-rise buildings, water cooling systems in factories, for example for cooling systems used for data centres or machinery, or water pressure management managed by water utilities. For a generator to suit a DN100 pipeline, the dimensions may be approximately length 450 mm x diameter 300 mm, with an estimated maximum power output of about 8 kW.

[0130] Comparing Figures 16 and 20, it will be observed that two methods of forming closely similar helical impeller are disclosed. When describing the shape of the impeller, it is useful to do so in terms of a notional slice of the impeller. It will be observed that a slice defined by notional planes coincident with main upstream and downstream faces of the segment 47 (Figure 8) comprises flight portions of closely similar form to flight portions within a corresponding notional slice of the rotor 149’.

[0131] Whilst Figures 16 and 20 illustrate four-helix impellers, there are other options, although it is preferred that the impeller is made up of at least notional slices such that

[0132] - each slice has ‘n’ (e.g. four) blades; and

[0133] - each slice has an axial length corresponding to ‘ 1 / n’ of a sine wave (see Figure 19a); so

[0134] - ‘n’ slices together form ‘n’ interleaved helixes each one sine wave long.

[0135] ‘n’ is preferably in the range of 2 to 6.

[0136] The inventors’ early work suggests that long helical flights are more robust and longer wearing, and can produce less noise and vibration, than propeller-like rotor blades. P1959PCAU

[0137] 18

[0138] It should be noted that the inline generator may be operated also as a pump by providing power to the assembly and driving the rotor to force the impeller to rotate. This will then generate a pumping force within that section of pipeline.

[0139] Preferably, at least the impeller flights are 3D printed.

[0140] It should be recognised that this invention may be scaled appropriately to service the diameter and flow rate of the section of pipeline into which it is inserted.

[0141] It should also be noted that this generator can be used in reverse by applying a power source to the assembly and thereby driving the impeller assembly to have the assembly operate as a pump. By this feature, this machine is also a Pump as Turbine (PAT) that can be used in the pumped storage power station once it is sized up.

[0142] Preferred variants are fully charged with liquid (e.g. water) when in operation.

[0143] While the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and / or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

[0144] It will be also understood that where the word ‘comprise’, and variations such as ‘comprises’ and ‘comprising’, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

[0145] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

Claims

P1959PCAU19CLAIMS1 . A generator comprising a rotor and a stator; wherein the rotor comprises a set of one or more helical flights upon which fluid acts to turn the rotor about a rotation axis; the set of one or more helical flights comprises a periphery via which elements are driven to rotate about a stator; the stator magnetically co-operates with the elements to produce electricity; a rotor portion is a portion of the rotor and bounded by two notional planes mutually parallel and each perpendicular to the rotation axis; and comprising one or more flight portions, of the one or more helical flights, helically turning through one or more helical-turn angles summing to a full turn; an outer circle has a radius and is a circle through which an outermost portion of the one or more flight portions turns; and when the rotor portion is notionally viewed in a rotation axis direction, a notional circular area concentric to, and having a radius half the radius of, the outer circle is at least 50% closed to direct axial flow.

2. The generator of claim 1 wherein an innermost portion of the one or more flight portions turns at a radius not more than 20% of the radius of the outer circle.

3. The generator of claim 1 or 2 wherein when the rotor portion is notionally viewed in a rotation axis direction, the outer circle is at least 90% closed to direct axial flow.P1959PCAU204. The generator of claim 1 wherein each of the one or more helical flights comprises at least 0.5 turns.

5. The generator of claim 1 wherein each of the one or more helical flights comprises at least 1 .0 turns.

6. The generator of any one of claims 1 to 5 wherein the set of one or more helical flights is a plural-flight set comprising plural of the flights axially aligned and angularly offset with respect to each other.

7. The generator of any one of claims 1 to 5 wherein the set of one or more helical flights is a four-flight set comprising four of the flights axially aligned and angularly offset with respect to each other.

8. The generator of any one of claims 1 to 7 wherein each of the one or more helical flights has a pitch in the range of 100% to 300% (inclusive) of the radius of the outer circle.

9. The generator of any one of claims 1 to 8 wherein adjacent convolutions of the one or more helical flights are axially separated by distance in the range of 25% to 75% (inclusive) of the radius of the outer circle.

10. The generator of any one of the claims 1 to 9 wherein the rotor comprises a housing about the periphery and carrying the elements.

11. The generator of claim 10 wherein the set of one or more flights is welded to the housing.

12. The generator of claim 10 wherein the rotor comprises two or more rotorsegments that are substantially identical to each other; are axially spaced with respect to each other; andP1959PCAU21 each define a portion of the housing and of the set of one or more helical flights.

13. The generator of claim 12 wherein each adjacent two segments of the two or more rotor-segments comprises features interlocking to mutually align the adjacent two segments.

14. A system comprising the generator of any one of claims 1 to 13; and downstream of the generator, a valve that closes in response to rising pressure downstream of the system.

15. A method of manufacturing a rotor for a generator; the method comprising welding a set of one or more helical flights into an interior of a cylindrical housing.

16. The method of claim 15 wherein the set of one or more helical flights is a plural-flight set comprising plural of the flights axially aligned and angularly offset with respect to each other.

17. The method of claim 16 comprising relatively-inserting and welding in place one of the plural flights, then relatively-inserting and welding in place another of the plural flights.

18. The method of claim 14, 15 or 16 comprising arranging a respective two or more helical flight-portions end-to-end to form each of the one or more helical flights.

19. The method of any one of claims 14 to 18 wherein the welding comprises welding via openings through a wall of the housing.P1959PCAU2220. The method of claim 19 comprising closing the openings.

21. A rotor-segment for a generator comprising a ring; and within the ring a set of one or more flight portions; wherein the rotor-segment is combinable with identical rotor-segments to form a rotor comprising a set of one or more helical flights upon which fluid acts to turn the rotor; and a housing about a periphery, of the set of one or more helical flights, via which drive is transmitted to the housing.

22. The rotor-segment of claim 21 wherein each adjacent two segments of the rotor comprises features interlocking to mutually align the adjacent two segments.

23. A method of starting a generator; wherein the generator is one of in accordance with any one of claims 1 to 13; and the generator of the system of claim 14; and the method comprises supplying electricity to the stator to rotationally drive the rotor.

24. An electrical generator assembly adapted for use inline in a pipeline wherein said electrical generator assembly includes:- a housing assembly, andP1959PCAU23- an impeller, and- a rotor containing a plurality of magnet pairs, and- a stator assembly, and- bearings, and- electrical contacts, and wherein the housing assembly is adapted to allow a flow of fluid that is flowing inside the pipeline network to flow directly through the generator assembly, and wherein a substantial portion of the flow in the pipeline impinges upon the impeller, forcing it to turn, and wherein the turning of the impeller causes the rotor to rotate around the centre axis of the impeller and interact with the stator to generate an electrical current that is then passed to the electrical contacts, and wherein the bearings support and reduce friction on the impeller, and wherein the impeller includes a plurality of interlocking pieces that are each keyed to lock with an adjacent piece so that as each piece is locked into place, the assembly thereby produced forms the shape of an impeller that runs substantially along the length of the housing assembly.

25. The electrical generator assembly of claim 24 comprising- a first flange and gasket, and- a second flange and gasket, wherein the first flange and gasket are adapted to be interconnected to an adjacent flange on the pipeline into which the electrical generator assembly is to be installed, and wherein the second flange and gasket, located at the opposite end to the first flange and gasket, are adapted to be interconnected to an adjacent flange on the pipeline thereby making the electrical generator assembly inline with the pipeline.

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