WO2013186551A2 - Structure de pièce de montant améliorée - Google Patents

Structure de pièce de montant améliorée Download PDF

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Publication number
WO2013186551A2
WO2013186551A2 PCT/GB2013/051533 GB2013051533W WO2013186551A2 WO 2013186551 A2 WO2013186551 A2 WO 2013186551A2 GB 2013051533 W GB2013051533 W GB 2013051533W WO 2013186551 A2 WO2013186551 A2 WO 2013186551A2
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WO
WIPO (PCT)
Prior art keywords
magnetic
pole
piece
piece structure
retaining
Prior art date
Application number
PCT/GB2013/051533
Other languages
English (en)
Other versions
WO2013186551A3 (fr
Inventor
Jeffrey George BIRCHALL
Original Assignee
Magnomatics Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Magnomatics Limited filed Critical Magnomatics Limited
Publication of WO2013186551A2 publication Critical patent/WO2013186551A2/fr
Publication of WO2013186551A3 publication Critical patent/WO2013186551A3/fr

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K51/00—Dynamo-electric gears, i.e. dynamo-electric means for transmitting mechanical power from a driving shaft to a driven shaft and comprising structurally interrelated motor and generator parts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
    • H02K1/246—Variable reluctance rotors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
    • H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
    • H02K15/022—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies with salient poles or claw-shaped poles
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K49/00—Dynamo-electric clutches; Dynamo-electric brakes
    • H02K49/06—Dynamo-electric clutches; Dynamo-electric brakes of the synchronous type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K49/00—Dynamo-electric clutches; Dynamo-electric brakes
    • H02K49/10—Dynamo-electric clutches; Dynamo-electric brakes of the permanent-magnet type
    • H02K49/104—Magnetic couplings consisting of only two coaxial rotary elements, i.e. the driving element and the driven element
    • H02K49/106—Magnetic couplings consisting of only two coaxial rotary elements, i.e. the driving element and the driven element with a radial air gap

Definitions

  • the present invention relates to pole-piece structures for use with magnetic gears and in magnetically-geared motors and generators.
  • Magnetic gears and magnetically-geared motors/generators typically employ an array of ferromagnetic pole-pieces which modulates the magnetic fields produced by two arrays of permanent magnets.
  • Known pole-piece structures often have a mark-space ratio of approximately 50% between a ferromagnetic material and a non-magnetic material (i.e. 50% is ferrous magnetic material and 50% is non-magnetic material).
  • the physical properties of the non-magnetic regions have a large impact on the physical properties of the pole-piece structure as a whole.
  • the two arrays of permanent magnets can, in one configuration, take the form of an inner rotor and an outer rotor representing an input rotor and an output rotor, and the array of pole- pieces can be located between the inner rotor and the outer rotor.
  • the number of pole- pieces embedded in the pole-piece structure is equal to the sum of the number of pole- pairs in the magnetic field produced by the permanent magnets on the inner and outer rotors.
  • one of the inner and outer rotors is a low speed or static rotor, and the other of the inner and outer rotors is a high speed rotor.
  • the modulation of the magnetic fields produced by the two arrays of permanent magnets allows one of the inner and outer rotors to drive the other.
  • the gear ratio between the inner and outer rotors can be continuously varied by varying the frequency of rotation of the pole-piece rotor.
  • the pole-piece array can form one of the input or output rotors.
  • the frequency of rotation of one of the inner and outer rotors (typically a high speed, low torque rotor) can be varied to vary the gear ratio between the other of the inner and outer rotors and the pole-piece rotor, which form the input and output rotors.
  • the radial thicknesses of the pole-pieces are selected to provide the optimum modulation of the permanent magnet rotor magnetic fields whilst preventing significant leakage and avoiding magnetic saturation, and to maximise the working point of each of the permanent magnet materials in each of the magnet arrays.
  • the working point of a magnet is the flux density at which it operates within a device and, hence, the magnetic flux it produces.
  • the working point of a magnet is determined by its magnetic properties i.e. its remanent flux density, or remanence, and its coercivity (both of which vary as a function of the material alloy composition), and the magnetic circuit into which it drives the flux.
  • the working point varies as a function of the magnet thickness and the magnetic circuit reluctance, which is usually largely affected by the magnetic airgap. Due to the 50% mark-space ratio of the pole-piece array, the pole-piece array has a large influence on the overall circuit reluctance.
  • the pole-pieces are small in the radial dimension (typically 5 mm to 20 mm thick) and, therefore, the pole-piece rotor is usually a relatively thin-walled annular structure.
  • the pole-pieces are usually formed from individual sheets of 0.2 mm to 0.5 mm thick silicon iron (SiFe) electrical steel. Therefore, these parts have a poor aspect ratio and have no integral mechanical strength, yet form part of the torque carrying structure of the machine.
  • the pole-pieces are subject to high forces from:
  • the magnetic pole-pieces cannot be free-standing components and are usually retained in some support structure or matrix to increase the system rigidity and constrain the deflection of the pole-pieces.
  • This support matrix must be non-magnetic (in order to allow correct modulation of the magnetic fields) and preferably nonconducting (to prevent eddy currents and losses being induced in the structure).
  • pole-pieces embedded within a structure (e.g. by resin filling a mould containing the pole-pieces or a pre-cast structure with pockets to insert the pole- pieces). Ideally, the pole-pieces should not be completely enclosed to allow some cooling air to impinge on the surfaces. Material above and below the pole-pieces also extends the magnetic airgap reducing magnetic (torque transmission) performance.
  • WO2009/138728A2 discloses that a support matrix can be created from glass-fibre or carbon-fibre composite components, often with mating male/female features on the pole-pieces. These composite components may engage with features on an end ring or plate to transmit the torque to the drive shaft.
  • the net shape required could be readily manufactured via carbon-fibre pultrusion, where fibres or resins are drawn through a die.
  • the pole-pieces may be bonded to the non-magnetic carriers using a suitable structural adhesive.
  • additional tie-rods preferably non-magnetic and non-conducting
  • These tie-rods may then be placed under tension, pre-tensioning the structure to reduce deflections due to drive torque and magnetic radial forces.
  • the present invention is aimed at improving on known pole-piece structures by allowing for a metallic support structure whilst impeding the flow of eddy currents. It is particularly relevant to high-speed applications where the centrifugal forces are significant and in applications where a small airgap/clearance between the rotors and, therefore, tight dimensional tolerances in the completed part are required.
  • the pole-piece structure of the present invention has additional benefits in terms of ease of manufacture. Summary of the Invention
  • the pole-piece structure of the present invention is designed to overcome the problems identified above.
  • a pole-piece structure comprising a plurality of laminae, wherein each lamina comprises at least one magnetic part and at least one metallic and non-magnetic retaining part.
  • the at least one retaining part will have a significantly lower magnetic relative permeability than the at least one magnetic part.
  • the at least one magnetic part preferably has a high magnetic relative permeability, preferably with an initial magnetic relative permeability greater than 100, which is typical of a ferromagnetic material, and more preferably is a good electrical steel with an initial magnetic relative permeability between 500 and 10,000 and a saturation flux density greater than LOT.
  • the at least one retaining part preferably has a low relative magnetic relative permeability, which can be similar to air, preferably with a magnetic relative permeability less than 10, and more preferably between 1.0 and 1.5.
  • a method for manufacturing a pole-piece structure comprising providing a plurality of laminae, each lamina comprising at least one magnetic part and at least one metallic and non-magnetic retaining part, and arranging the laminae to form a pole-piece structure.
  • the at least one magnetic part and the at least one retaining part may be affixed to one another.
  • the at least one magnetic part and the at least one retaining part may be bonded, laser- welded or friction stir welded to one another.
  • the at least one magnetic part can alternatively be friction stir welded to the at least one retaining part.
  • Magnetic parts and retaining parts may be arranged in an alternating pattern.
  • Each magnetic part may comprise silicon iron (SiFe).
  • Each retaining part may comprise non-magnetic stainless steel or austenitic steel, or other materials with significantly lower magnetic permeability than magnetic materials, such as electrical steel, for example SiFe electrical steel.
  • Each lamina may have a thickness of no more than approximately 0.5 mm.
  • Each lamina may have a thickness of no more than approximately 0.35 mm.
  • Each lamina may have a thickness of no more than approximately 0.2 mm.
  • the laminae may be arranged in a stack.
  • Each lamina may be substantially ring-shaped.
  • the magnetic part(s) of each lamina may be substantially aligned with one another, and the retaining part(s) of each lamina may be substantially aligned with one another, such that the pole-piece structure comprises at least one magnetic pole-piece and at least one retaining piece, wherein the at least one magnetic pole-piece and the at least one retaining piece extend through the plurality of laminae.
  • a reinforcement means may extend through the plurality of laminae.
  • the reinforcement means may comprise at least one substantially rigid elongate member extending through at least one retaining piece.
  • the reinforcement means may comprise at least one substantially rigid elongate member extending through at least one magnetic pole-piece.
  • the reinforcement means may comprise a plurality of rigid elongate members extending through at least one magnetic pole-piece and at least one retaining piece.
  • the pole-piece structure may further comprise at least one end-piece.
  • the at least one end-piece may be a ring having a cross-section which substantially matches the cross- section of the plurality of laminae.
  • the pole-piece structure may have two end-pieces located at opposing ends of the plurality of laminae, wherein the reinforcement means extends between the two end-pieces.
  • the reinforcement means comprises at least one substantially non-magnetic member which passes through at least one of the ferromagnetic pole-pieces, there is the advantage that the magnetic flux will travel around a non-magnetic bar (due to the higher permeability) and no flux will "cut" the bar, thereby preventing eddy currents being induced (provided each non-magnetic reinforcement member is isolated and does not form a circuit with another member via the end-rings). If the bars are within the ferromagnetic region, they can also be ferromagnetic (e.g. mild steel) without effecting the modulation of the field.
  • ferromagnetic e.g. mild steel
  • the reinforcement means passes through at least one of the non-magnetic retaining pieces, it will preferably be non-magnetic so as not to alter the modulation of the magnetic field.
  • the reinforcement members would preferably be isolated from one another and/or the end rings to prevent a cage structure being formed in which induced eddy currents could flow.
  • a magnetic gear comprising a first member having a first set of magnetic poles, a second member having a second set of magnetic poles, and a third member being the pole-piece structure of the present invention, wherein the first, second and third members are arranged in a magnetically-geared manner.
  • the third member can be arranged to modulate the magnetic field acting between the first and second members.
  • the first, second and third members can be rotors. Rotation of one of the members can be controlled so as to vary the gear ratio between the other two members.
  • an electrical machine comprising the magnetic gear of the present invention, and further comprising a winding arranged to interact magnetically with a magnetic field of the first set of magnetic poles.
  • a power generation system comprising: the electrical machine of the present invention; means for moving one of the moveable members of the electrical machine and thus for driving another of the moveable members of the electrical machine in a magnetically-geared fashion thereby inducing an electric current in the winding; and output means for outputting the electric current as electrical power.
  • the means for moving one of the moveable members can comprise a turbine, such as a wind turbine or water turbine which is coupled to a shaft connected to one of the moveable members of the electrical machine.
  • the winding can be connected via electrical wiring to the 3-phase electrical grid (directly or through a power electronic inverter), or through an inverter or rectifier to a battery for energy storage.
  • a motor system comprising: the electrical machine of the present invention; power supply means for energising the winding thereby producing a magnetic field configured to cause movement of one of the moveable members of the electrical machine and thus to drive another of the moveable members of the electrical machine in a magnetically-geared fashion; and coupling means configured for coupling the driven moveable member to a load.
  • the power supply means can comprise electrical wiring providing electrical energy to the winding, from the electrical grid or from a battery, potentially via a power electronic inverter to provide an AC current of variable frequency and amplitude (allowing control of speed and torque) and to ensure the currents are correctly commutated relative to the rotor position.
  • the load can be a wheel, or a propeller or impellor coupled via a turbine, or any other motive appliance which can be coupled to a shaft connected to the driven moveable member of the electrical machine.
  • the pole-piece structure of the present invention is particularly suitable for use as a pole-piece rotor in high-speed applications where the centrifugal forces are significant and in applications where a small airgap/clearance between rotors is desired, meaning that tight dimensional tolerances in the completed part are required.
  • the structure described above enables an all-metallic construction whilst preventing excessive eddy currents and losses.
  • An all-metallic construction increases the strength and robustness of the pole-piece rotor. Further, a stiffer rotor allows for pole-pieces with a reduced radial dimension. This enhances electromagnetic performance and therefore allows for a higher torque density and, consequently, a shorter machine.
  • Figure 1 shows a cross-sectional view of a prior art magnetic gear assembly
  • Figure 2 shows a cross-sectional view of a prior art magnetically-geared motor/generator
  • Figure 3 shows a side view and front view of a prior art pole-piece rotor
  • Figure 4 shows a perspective view of a pole-piece structure in accordance with one embodiment of the present invention
  • Figures 5A to 5F show the stages in an exemplary method of constructing a pole-piece structure in accordance with the embodiment shown in Figure 4.
  • Figure 6 shows an exemplary joining between a magnetic part and a retaining part of a pole-piece structure according to an embodiment of the present invention.
  • the pole-piece structure of the present invention is designed for use in magnetic gears 1 , such as that shown in Figure 1 , and magnetically-geared motors and generators 2, such as that shown in Figure 2.
  • Figure 1 depicts a magnetic gear assembly 1 consisting of an inner rotor 12 and an outer rotor 14, both of which comprise arrays of permanent magnets 16.
  • a pole-piece structure 10 is arranged so as to modulate the magnetic fields produced by the inner 12 and outer 14 rotors, thereby enabling the inner rotor, outer rotor and pole-piece structure to interact in a magnetically-geared manner.
  • one of the inner 12 and outer 14 rotors is a low speed rotor, and the other of the inner 12 and outer 14 rotors is a high speed rotor.
  • the pole- piece structure 10 is located between the inner 12 and outer 14 rotors and acts to modulate the magnetic fields produced by the inner 12 and outer 14 rotors, thereby allowing one of the inner 12 and outer 14 rotors to drive the other.
  • the gear ratio between the inner 12 and outer 14 rotors is fixed if the pole-piece rotor is held stationary but can be continuously varied by providing a rotatable pole-piece structure 10 and varying the frequency of rotation of the pole-piece structure 10.
  • the operation of magnetic gears 1 such as that depicted in Figure 1 is described in detail in WO2009/103993A1 and WO2009/130456A2.
  • Figure 2 shows a magnetically-geared motor or generator 2 which is a development of the magnetic gear arrangement 1 shown in Figure 1.
  • a stator 18 comprising a core, which can optionally be laminated, and a winding is positioned external to an inner rotor 12, a pole-piece rotor 10 and an outer rotor 14 as described above with reference to Figure 1.
  • the configuration shown in Figure 2 can be used as a generator by providing means for moving one of the rotors 10, 12, and thus for driving another of the rotors 10, 12, in a magnetically-geared fashion thereby inducing an electric current in the winding.
  • Output means can be provided for outputting the electric current as electrical power.
  • the configuration shown in Figure 2 can be used as a motor by providing power supply means for energising the winding thereby producing a magnetic field configured to cause movement of one of the rotors 10, 12, and thus to drive another of the rotors 10, 12, in a magnetically-geared manner.
  • Coupling means can be provided which is configured for coupling the driven rotor to a load.
  • Figure 3 shows a basic configuration of a known pole-piece rotor 10 suitable for use in a magnetic gear 1 such as that shown in Figure 1 and/or a magnetically-geared motor/generator 2 such as that shown in Figure 2.
  • the pole-piece rotor 10 preferably comprises at least one magnetic part 100 and at least one retaining part 102, which is preferably non-magnetic.
  • the pole-piece rotor 10 comprises a plurality of magnetic parts 100 and a plurality of non-magnetic retaining parts 102 which are arranged in an alternating pattern.
  • the magnetic parts 100 can, for example, comprise laminated electrical steel manufactured from non-orientated silicon iron (SiFe). Alternatively, another magnetic material can be used.
  • the number of magnetic parts 100 and retaining parts 102 can be designed to be equal, and is preferably equal to the sum of the number of permanent magnets included in the inner 12 and outer 14 rotors of magnetic gears or magnetically-geared machines such as those shown in Figures 1 and 2, thereby allowing the pole-piece rotor 10 to modulate the magnetic fields produced by the permanent magnets of the inner 12 and outer 14 rotors.
  • the present invention provides an improved pole-piece structure which is particularly suitable for use in high-speed applications where the pole-piece structure is subjected to significant centrifugal forces.
  • Figure 4 shows a pole-piece structure 20 in accordance with an embodiment of the present invention.
  • the pole-piece structure 20 shown in Figure 4 comprises a plurality of laminae 204, wherein each lamina comprises at least one magnetic part 200 comprising a substantially magnetic material (e.g. with a high magnetic relative permeability, preferably with an initial magnetic relative permeability greater than 100, which is typical of a ferromagnetic material, and more preferably a good electrical steel with an initial magnetic relative permeability between 500 and 10,000 and a saturation flux density greater than LOT) and at least one preferably non-magnetic and preferably metallic retaining part 202, which can comprise a substantially non-magnetic material (e.g.
  • a substantially magnetic material e.g. with a high magnetic relative permeability, preferably with an initial magnetic relative permeability greater than 100, which is typical of a ferromagnetic material, and more preferably a good electrical steel with an initial magnetic relative permeability between 500 and 10,000 and a saturation flux density greater than LOT
  • the at least one magnetic part 200 and the at least one retaining part 202 are preferably affixed to one another e.g. through bonding, laser-welding or friction stir welding.
  • magnetic part(s) 200 and retaining part(s) 202 are arranged in an alternating pattern.
  • the laminae 204 can be stacked to form the pole-piece structure 20.
  • the laminae 204 can optionally be bonded together to form the pole-piece structure 20.
  • the laminae 204 take the form of rings, and the pole-piece structure 20 takes the form of a rotor in the example shown in Figure 4.
  • many other configurations are applicable and will be understood by the skilled reader.
  • the magnetic parts 200 comprise electrical steel or silicon-iron (SiFe). It is preferable, in the interest of providing a strong and robust pole- piece rotor 20 suitable for high speed applications, for the non-magnetic parts 202 to be metallic (non-magnetic steel/austenetic steel, such as cold rolled 316L stainless steel for example).
  • each ring 204 comprises a plurality of magnetic parts 200 and a plurality of retaining parts 202. Typically, the number of magnetic parts 200 is equal to the number of retaining parts 202.
  • the magnetic parts 200 and retaining parts 202 are arranged in an alternating pattern around the ring 204.
  • each ring 204 preferably has substantially the same cross-sectional shape and/or dimensions.
  • the rings 204 are also preferably of substantially equal thickness.
  • each ring 204 can have a thickness of up to 0.5 mm, up to 0.35 mm, or up to 0.2 mm.
  • the pole-piece structure 20 can optionally further comprise a reinforcement means 210 extending through the plurality of rings 204, which is shown in Figure 4.
  • This reinforcement means 210 can typically take the form of at least one substantially rigid elongate member.
  • one or more elongate steel bars, rods or poles can extend through one or more holes 212 through one or more of the retaining pieces 208 or through one or more of the magnetic pieces.
  • the reinforcement means comprises at least one substantially non-magnetic member which passes through at least one of the ferromagnetic pole-pieces, there is the advantage that the magnetic flux will travel around a non-magnetic bar (due to the higher permeability) and no flux will "cut" the bar, thereby preventing eddy currents being induced (provided each non-magnetic reinforcement member is isolated and does not form a circuit with another member via end pieces of the pole-piece structure (see below)). If the bars are within the ferromagnetic region, they can also be ferromagnetic (e.g. mild steel) without effecting the modulation of the field.
  • ferromagnetic e.g. mild steel
  • the reinforcement means passes through at least one of the non-magnetic retaining pieces, it will preferably be non-magnetic so as not to alter the modulation of the magnetic field.
  • the reinforcement members would preferably be isolated from one another and/or any end rings of the pole-piece structure to prevent a cage structure being formed in which induced eddy currents could flow.
  • the reinforcement means typically comprises stainless steel rod(s) with threaded ends. High tensile steels can be employed, if required.
  • the rods are located within the magnetic pole-pieces they may be manufactured from mild steel.
  • the rods may also be preformed shoulder bolts with a fastener end and a threaded end that locates in a threaded hole in the end ring.
  • the hole(s) 212 through which the reinforcement means 210 extends can be formed by punching or drilling, for example. These holes would typically be formed at the time of producing each lamination i.e. during the stamping or laser-cutting process.
  • the hole(s) 212 can be formed in each individual lamina 204 and then aligned with each other. Alternatively, the laminae 204 can be first stacked and then the hole(s) 212 can be formed through the entire pole-piece structure 20.
  • a reinforcement means 210 extends through every retaining piece 208. In another embodiment, a reinforcement means 210 extends through every other retaining piece 208 within the circumferential array.
  • the reinforcement means 210 can be secured at one or both of its ends to one or more end pieces 214 located at at least one end of the stack of rings 204.
  • the securement between the reinforcement means 210 and the end piece(s) 214 can increase the structural rigidity, strength and robustness of the pole-piece structure 20.
  • two end pieces 214 can be provided at opposing ends of the stack of rings 204 and the reinforcement means 210 can be secured to both end pieces 214.
  • the end piece(s) 214 can be constructed from any suitable material, such as aluminium or stainless steel or a composite structure (e.g. fibre reinforced plastic). Any suitable form of securement can be used to attach the reinforcement means 210 to one or more end pieces 214.
  • the reinforcement means 210 which can take the form of one or more substantially rigid elongate members, passes through one or more holes in the end piece(s) 214 and can be secured to the end piece(s) 214 using a nut and/or bolt 216, for example, which may matingly engage with one or more threaded holes in the end-piece(s).
  • the reinforcement means 212 can be bonded or welded to the end piece(s) 214 or can be attached to the end piece(s) 214 using an adhesive.
  • the reinforcement means 210 can also be integrally formed with the end piece(s) 214, or can be attached via an intermediate joining or mounting, or may simply be dowel pins located within corresponding blind holes.
  • the dowel pins can be constructed from similar materials to the threaded members discussed above (i.e. mild steel if located within the pole-pieces, stainless steel if located in the intermediate regions), or can alternatively be constructed from a plastic or composite material. As shown in Figure 4, the end pieces 214 can have substantially the same cross-sectional shape and/or dimensions as the plurality of rings 204.
  • a cut-out 218 is removed from a laminar sheet of magnetic material, typically a non-orientated electrical steel, such as silicon iron (SiFe).
  • a window 230 is formed in a sheet 220 of non-magnetic, preferably metallic material, such as nonmagnetic stainless steel or austenitic steel.
  • the window 230 preferably has substantially the same shape as the cut-out 218, meaning that the cut-out 218 can be placed inside and can conform to the window 230, as shown in Figure 5C.
  • the cut-out 218 and window 230 can be formed from larger sheets of magnetic and non-magnetic material, respectively, by electrical discharge machining, wire erosion, photo-etching, laser cutting or stamping, for example.
  • a cut-out constructed from non-magnetic material can be placed inside and can conform to a complimentarily-shaped window in a sheet of magnetic material i.e. the magnetic and non-magnetic portions in Figures 5A to 5C are reversed.
  • the magnetic cut-out 218 is then affixed (e.g. bonded, laser- welded or friction stir welded) to the edge of the window 230 in the non-magnetic material.
  • the cut-out 218 is preferably laser-welded to the edge of the window 230.
  • Laser-welding is a tightly-controlled and localised joining method.
  • medium-powered lasers are suitable (fibre optic YAG lasers are good and fibre lasers would also be highly suitable).
  • Argon provides very good shielding for preventing oxidisation and impurities which will prevent the weld from forming.
  • Conduction welding as opposed to penetration welding (keyhole welding), can be employed to provide a neat weld on thin materials. Welding from both sides is not necessary with conduction welding as a weld pool forms on both surfaces when welding from one side with the correct settings. Power, spot size and weld speed are all typically adjusted to achieve the best weld characteristic. In some cases, a spot size in the region of 50 to 200 micrometers can be achieved.
  • Jigging can be used to ensure close tolerances between parts are held prior to the weld process as large gaps between thin materials will not weld. No filler material is required in the laser-welding process and welding grades of stainless steel (316L) to electrical steel is possible.
  • An alternative joining method which can also be employed is friction stir welding. This provides a neat, high strength weld between dissimilar steels of different phases. Tool life is not a concern for this application. A suitable weld speed can also be achieved.
  • a ring 204 comprising alternating magnetic 200 and non-magnetic 202 sections can be cut, for example, by electrical discharge machining, wire erosion or laser cutting as shown in Figure 5D.
  • This cutting process results in a ring 204 as shown in Figure 5E.
  • a plurality of substantially similar rings 204 can be produced using the steps discussed above with reference to Figures 5A to 5E.
  • they can be stacked as shown in Figure 5F to form a rotor comprising a laminated stack of rings 204 of a desired length.
  • the complete pole-piece structure 20 (which can additionally include a reinforcement means 210 and/or end-piece(s) 214 as described above) is preferably that shown in Figure 4 and described in detail above.
  • the arrays of magnetic and non- magnetic regions may be initially produced as joined parts.
  • the ring 204 shown in Figure 5E may initially be produced from magnetic and non-magnetic parts using a stamping technique, for example. The magnetic and non-magnetic parts can then be held in place while a series of welds are performed (e.g. using a CNC laser- welding machine).
  • each pole-piece and retaining part may be provided as separate components (rather than being held together in a ring).
  • Having separate components increases the component count but simplifies the required tolerances to achieve a suitable alignment between the parts (as laser-welding, for example, requires close contact between the thin sheet materials for optimum joining).
  • separate intermediate non-magnetic wedge-shape parts can be located between the "fingers" of a single joined magnetic part. This allows variation in the radial location of the separate parts prior to the joining/welding process, to overcome any manufacturing tolerance/variations, and ensure good contact at the edges.
  • Having separate components also reduces the potential for any distortion of the components during the bonding and manufacturing process due to any differences in thermal growth of stresses that may occur (or be relieved) during the bonding/welding process.
  • a plurality of laminar sheets of non-magnetic material and a plurality of laminar sheets of magnetic material can be assembled and a a cut-out comprising a plurality of laminae can be cut therefrom.
  • the magnetic pole-pieces 206 and retaining pieces 208 of the pole-piece structure 20 described above with reference to Figure 4 can be assembled as whole pieces and subsequently bonded or laserwelded to one another to form a pole-piece structure 20.
  • holes 212 can be cut through one or more of the non-magnetic regions and/or one or more of the magnetic regions so that a reinforcement means 210 as described above can be inserted therethrough.
  • the holes can be formed by drilling or punching, or can be included at the time of cutting/stamping the laminations for example.
  • the holes 212 can be cut in each individual lamina before assembly of the pole-piece structure 20.
  • the pole-piece structure 20 can be assembled and holes 212 can subsequently be formed through a plurality of laminae 204 at once.
  • laminae having the structure shown in Fig. 5C are stacked on top of one another to establish a stack of the required height (i.e. the required number of laminae) with the required holes 212.
  • a ring shape is then cut out of the stack to form a rotor having the desired number of rings 204.
  • the pole-piece structure is particularly suited to high-speed applications where the centrifugal forces are significant and in applications where a small airgap/clearance between the rotors is required, requiring tight dimensional tolerances in the completed part.
  • the pole-piece structure according to the present invention enables an all-metallic construction whilst preventing excessive eddy currents and losses. Eddy currents are induced in a conductor when it is exposed to a changing magnetic field. Therefore, a solid metallic pole-piece structure would be highly susceptible to the circulation of eddy currents within the structure, resulting in energy loss.
  • a metallic structure has been precluded in prior art designs due to the aforementioned losses which would be induced in a solid metallic structure.
  • a non-metallic matrix made from plastic or a composite material, for example, has been typically employed.
  • Such a structure often does not prove to be sufficiently stiff to withstand the large magnetic and centrifugal loads.
  • these plastic or composite structures may be adversely affected by high operating temperatures which may occur due to high ambient operating temperatures (e.g. downhole operation in oil & gas applications or under the hood automotive applications) and/or due to heat generated due to other loss mechanisms within the magnetic gear or magnetically-geared motor/generator (e.g. winding copper losses).
  • each complete laminated ring can be insulated from adjacent rings by an insulating layer, such as an applied varnish (e.g. Suralac 7000, a C5 inorganic coating), an adhesive bonding layer used to stack the laminations, or through surface oxidation.
  • an insulating layer such as an applied varnish (e.g. Suralac 7000, a C5 inorganic coating), an adhesive bonding layer used to stack the laminations, or through surface oxidation.
  • an insulating layer such as an applied varnish (e.g. Suralac 7000, a C5 inorganic coating), an adhesive bonding layer used to stack the laminations, or through surface oxidation.
  • an insulating layer such as an applied varnish (e.g. Suralac 7000, a C5 inorganic coating), an adhesive bonding layer used to stack the laminations, or through surface oxidation.
  • Other insulating means can equally be used. This prevents the flow of currents along the length of the lamination stack.
  • the pole-piece rotor of the present invention also allows for small airgaps within the machine due to the higher dimensional tolerances that can be achieved.
  • the at least one magnetic part 200 and the at least one retaining part 202 can be affixed to one another e.g. through bonding, laser-welding or friction stir welding.
  • the at least one magnetic part 200 and the at least one retaining part 202 can be connected, joined or coupled together by providing magnetic part(s) 200 and retaining part(s) which are complimentarily shaped.
  • Figure 6 shows an example of such shaping of the magnetic part(s) 200 and retaining part(s).
  • a magnetic part 200 and a retaining part 202 interlock with each other.
  • the interlocking is achieved by providing male and female interlocking features on the magnetic part 200 and the retaining part 202.
  • any suitable complimentary shaping between the magnetic part(s) 200 and the retaining part(s) 202 can be used to connect, join or couple the magnetic part(s) 200 and the retaining part(s) 202.
  • such shaping removes the need for bonding, laser-welding or friction stir welding, thereby simplifying the manufacturing process.
  • complimentary shaping for example using interlocking features (e.g. male and female interlocking features) between the magnetic part(s) 200 and the retaining part(s) 202, can be used to connect, join or couple the magnetic part(s) 200 and the retaining part(s) 202, and the magnetic part(s) 200 and retaining part(s) 202 can then be bonded, laser-welded or friction stir welded to one another to strengthen the connection, joining or coupling.
  • interlocking features e.g. male and female interlocking features

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)
  • Linear Motors (AREA)
  • Manufacturing & Machinery (AREA)

Abstract

La présente invention concerne une structure de pièce de montant et son procédé de fabrication. La structure de pièce de montant comprend une pluralité de lames, chaque lame comprenant au moins une partie magnétique et au moins une partie de retenue métallique et non magnétique. La structure de pièce de montant est particulièrement adaptée aux applications à grande vitesse.
PCT/GB2013/051533 2012-06-11 2013-06-11 Structure de pièce de montant améliorée WO2013186551A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB201210240A GB201210240D0 (en) 2012-06-11 2012-06-11 Improved pole-piece structure
GB1210240.6 2012-06-11

Publications (2)

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WO2013186551A2 true WO2013186551A2 (fr) 2013-12-19
WO2013186551A3 WO2013186551A3 (fr) 2014-12-24

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Publication number Priority date Publication date Assignee Title
CN104682660A (zh) * 2015-02-13 2015-06-03 江苏大学 一种轴向磁场调制式磁性齿轮
EP3118972A4 (fr) * 2014-03-12 2018-01-03 IHI Corporation Élément pôle magnétique annulaire, et dispositif d'engrenage à onde magnétique
WO2021078664A1 (fr) * 2019-10-25 2021-04-29 Thyssenkrupp Presta Ag Système de direction à commande électrique pourvu d'un actionneur rétroactif comprenant un couplage de transmission magnétique
WO2023203868A1 (fr) * 2022-04-22 2023-10-26 三菱重工業株式会社 Unité de pièce polaire et machine électrique à engrenage magnétique
EP4310367A4 (fr) * 2021-03-18 2024-04-24 Mitsubishi Electric Corp Dispositif d'engrenage magnétique et machine électrique tournante

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WO2009103993A1 (fr) 2008-02-21 2009-08-27 Magnomatics Limited Engrenages magnétiques variables
WO2009130456A2 (fr) 2008-04-23 2009-10-29 Magnomatics Limited Machines électriques
WO2009138728A2 (fr) 2008-05-12 2009-11-19 Magnomatics Limited Support de pièce à pôle magnétique

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GB0800463D0 (en) * 2008-01-11 2008-02-20 Magnomatics Ltd Magnetic drive systems
WO2011036552A1 (fr) * 2009-09-28 2011-03-31 Stellenbosch University Engrenage magnétique
US8786158B2 (en) * 2010-08-19 2014-07-22 L. H. Carbide Corporation Continuously formed annular laminated article and method for its manufacture

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009103993A1 (fr) 2008-02-21 2009-08-27 Magnomatics Limited Engrenages magnétiques variables
WO2009130456A2 (fr) 2008-04-23 2009-10-29 Magnomatics Limited Machines électriques
WO2009138728A2 (fr) 2008-05-12 2009-11-19 Magnomatics Limited Support de pièce à pôle magnétique

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3118972A4 (fr) * 2014-03-12 2018-01-03 IHI Corporation Élément pôle magnétique annulaire, et dispositif d'engrenage à onde magnétique
CN104682660A (zh) * 2015-02-13 2015-06-03 江苏大学 一种轴向磁场调制式磁性齿轮
WO2021078664A1 (fr) * 2019-10-25 2021-04-29 Thyssenkrupp Presta Ag Système de direction à commande électrique pourvu d'un actionneur rétroactif comprenant un couplage de transmission magnétique
EP4310367A4 (fr) * 2021-03-18 2024-04-24 Mitsubishi Electric Corp Dispositif d'engrenage magnétique et machine électrique tournante
WO2023203868A1 (fr) * 2022-04-22 2023-10-26 三菱重工業株式会社 Unité de pièce polaire et machine électrique à engrenage magnétique

Also Published As

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WO2013186551A3 (fr) 2014-12-24
GB201210240D0 (en) 2012-07-25

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