AU2020205316B2 - Improvements in, or related to, electromagnetic devices and methods therefor - Google Patents

Abstract

The invention disclosed is for a core assembly for an electromagnetic device. The core has a core sub-assembly of, a core of first magnetically permeable material, extending in a first direction, a wrap of a first insulating material at least in part enclosing the core 5 about its exterior surface, at least one end cap, of a second material, connecting to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, at least one winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained 10 in the first direction by the inwardly presenting guide portion, at least one wound yoke of second magnetically permeable material, applied to at least one core assembly, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion(s), and an electrical connection and/or mechanical connection between the core subassembly(s) and a reinforcement joiner. The resulting 15 core assembly of one or more core sub-assemblies can be used to form an electromagnetic device when appropriately connected and powered.

Description

IMPROVEMENTS IN, OR RELATED TO, ELECTROMAGNETIC DEVICES AND METHODSTHEREFOR

TECHNICAL FIELD OF THE INVENTION The present invention relates to electromagnetic devices, and methods therefor.

In particular, though not solely, the present invention is directed to apparatus for assembling an electromagnetic device, and methods of assembling such devices for use in a transformer or reactor.

BACKGROUND OF THE INVENTION In transformers or reactors for use with electricity it is necessary to create a continuous magnetic path between the ends of each core. To date this has been done in a number of ways. The typical linear arrangement has a stack of metal laminations cut to length and situated at each end of the cores and their windings. Even in a standard moderate sized transformer this may require hundreds or even thousands of individual metal laminations. These need to be cut to size, typically ahead of time. This also means storing the cut laminations and then providing in the correct order for assembly. On top of this there is the time spent cutting and punching the laminations, and the additional waste material that is formed.

In the case of 3-phase devices, which typically have three cores, there have been a number of methods to enable triangular arrangements of the cores and windings.as shown in the examples given below. These methods all require the formation of particular shaped laminations that are meshed or jointed in such ways as to optimise the magnetic coupling at the core ends.

US2367927 discloses a triangular 3-phase core comprising continuously wound cores to form a star arrangement. The windings must be formed onto pre-formed cores which for the shape and accuracy required is a difficult process.

US2456461 and discloses a triangular 3-phase core comprising individually formed overlapping laminations to form a star configuration. This requires significant cutting and folding processes to a high degree of precision.

US2486220 discloses a triangular 3-phase core and ends with individual laminations to form a star configuration by means of a distributed gap technique. This requires significant cutting and folding processes to a high degree of precision.

US9007162 discloses a triangular 3-phase core and ends with individual laminations folded at the ends to form a star configuration. This requires significant cutting and folding processes to a high degree of precision.

US2016/005536 discloses a triangular 3-phase core and ends with individual laminations shaped to produce a delta laminated arrangement. This requires significant cutting processes to a high degree of precision. The clamping arrangements are also mechanically complex.

US2018/0130594 discloses a triangular 3-phase core and ends with individual laminations folded at the ends to form a star configuration with interleaving as required to achieve minimal air gap. This requires complex cutting and folding to a high degree of precision.

In particular, triangular transformer arrangements are becoming more widespread in their application due to the better electrical characteristics and lower material cost required. The designs the inventor is aware of all suffer from the problem of significant time to build due to the manner by which the ends of the cores are magnetically joined. Distributed air gap technology and interleaving of laminations all require precision machinery to cut and form the laminations to the precise dimension required to achieve the effect, for example as outlined above. This is both costly to manufacture and requires expensive machinery and maintenance.

Further disadvantages occur with this method of manufacture as often the final reactor or transformer will need to be tuned to provide the correct desired performance. This can add a further separate step to the manufacturing process and is not efficiently achievable.

In some earlier designs, the windings must be formed onto the completed core assembly (forming a complete loop) which can prove to be an impediment to mass production.

In other designs, the folding and interleaving of laminations is an intricate and laborious process which also does not lend itself to high volume production.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in any jurisdiction, are prior art, or form part of the common general knowledge in the art.

It is an object of the present invention to provide an improved electromagnetic device and the method for manufacturing such an electromagnetic device, the device and method providing an improvement over existing devices, ease of assembly and manufacture, or to overcome the above shortcomings or address the above desiderata, or to at least provide the public with a useful choice.

Further objects of the invention will become apparent from the following description.

BRIEF DESCRIPTION OF THE INVENTION In a first aspect, the present invention may be said to broadly consist in a core assembly for an electromagnetic device, comprising or including, A core sub-assembly of, A core of first magnetically permeable material, extending in a first direction, A wrap of a first insulating material at least in part enclosing the core about its exterior surface, At least one end cap, of a second material, connecting to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, At least one winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained in the first direction by the inwardly presenting guide portion, At least one wound yoke of second magnetically permeable material, applied to at least one core assembly, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion(s), An electrical connection and/or mechanical connection between the core subassembly(s) and a reinforcement joiner, Whereby the resulting core assembly of one or more core sub-assemblies can be used to form an electromagnetic device when appropriately connected and powered.

Preferably the core is a laminated one.

Preferably the core is made from a magnetically permeable material.

Preferably the core is substantially circular, square or rectangular in cross section.

Preferably the core is a full length core or comprises multiple shorter core(s).

Preferably there are two end caps, one for each end of the core.

Preferably the second material is either an insulating material and/or a magnetically permeable material

Preferably the end cap is shaped, at least on part of its periphery between the inwardly presenting guide portion and the outwardly presenting guide portion, to be complimentary to an end cap of a neighbouring core sub-assembly.

Preferably there is are two reinforcement joiners, one for each end of the core assembly.

Preferably the reinforcement joiner is made from a magnetically non-permeable material.

Preferably the reinforcement joiner is at least mechanically, if not electrically also, connected to the end ofthe core.

Preferably there are two wound yokes, one for each end of the core assembly.

Preferably the wound yoke is of a dimension such as diameter to achieve the desired magnetic coupling characteristic.

Alternatively the wound yoke is corrected to the required length or diameter as part of a tuning procedure, during or after manufacture of the core assembly to achieve the desired magnetic coupling characteristic.

Alternatively the wound yoke is positioned relative to the core and or the winding in the first direction either due to the thickness of the planar guide, or the positioning of the end cap to achieve the desired magnetic coupling characteristic.

Preferably there are additional mechanical connections from the end cap into the winding.

Preferably the at least one winding forms one or more layers of non-magnetically permeable, electrically conductive material.

Preferably the at least one winding has provision for at least one electrical connection for that winding.

Preferably the at least one winding is separated from the wound yoke by the end cap.

Preferably there are two or more windings.

Preferably there is another wrap, or other insulation between each of the two or more windings.

Preferably the two end caps and the wrap encase the core with the exception of a longitudinal aperture running at least part way from one end cap to the other.

Preferably the longitudinal aperture allows for compaction of the at least one end cap and wrap when the at least one first winding is applied.

Preferably the at least one winding can be of elongate or planar form.

Preferably the at least one winding can be formed in situ by winding onto the core, wrap and end cap(s), or may be pre-formed and pressed onto the assembly of the core and wrap, and or end cap.

Preferably the inwardly presenting guide portion and the outwardly presenting guide portion are on opposing sides of the end cap, and are substantially parallel to each other.

Preferably the core assembly, or core sub-assembly, or both is potted or glued to insulate and prevent or reduce vibration.

Preferably the longitudinal aperture allows for greater penetration into the core assembly of the potting compound or glue.

In another aspect the present invention may be said to broadly consist in a method of manufacture of a core assembly for an electromagnetic device, comprising or including the steps in any order of, 1. Forming a core sub-assembly from the steps of, a. Providing a core of first magnetically permeable material extending in a first direction, Applying a wrap of a first insulating material at least in part enclosing the core about its exterior surface, b. Connecting at least one end cap, of a second insulating material, to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, c. Applying at least one first winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained in the first direction by the inwardly presenting guide portion, 2. Connecting to at least one core sub-assembly, at least one wound yoke of second magnetically permeable material to the at least one end cap, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion, 3. Providing or making an electrical connection and/or mechanical connection between the core(s) and a reinforcement joiner, Whereby the resulting core assembly can be used as an electromagnetic device when appropriately connected and powered.

Preferably the method includes the step of assembling multiple core sub-assemblies together to which the at least one wound yoke is, or can be applied.

Preferably the method includes the step of applying another end cap to the other end of the core sub-assembly.

Preferably the wound yoke is formed by one continuous strip of the second magnetically permeable material by winding in a continuous spiral.

Preferably there is a wound yoke at each end of an assembly of the core-sub-assembly or subassemblies.

Preferably the provision to retain the wound yoke is a protrusion to wrap the wound coupling coil onto, or to engage into an interior periphery thereof.

Preferably the provision is made by one end cap by itself, or two or more end caps to in combination provide the provision.

Preferably the wound yoke can be formed in situ on the end cap(s), or may be pre-formed and pressed onto the end cap(s).

Preferably the step of winding the wound yoke in situ, or pressing onto the end caps, when the provision is made in combination from one or more end caps, tightens provisions to together to tie the end caps together.

Preferably the wound yoke is wound to the required length or diameter to achieve the desired magnetic coupling characteristic.

Alternatively the wound yoke is corrected to the required length or diameter as part of a tuning procedure, during or after manufacture of the core assembly.

Alternatively the wound yoke is adjusted in the first direction relative the core and winding either by the relative position of the end cap(s), the thickness of the planar guide as part of a tuning procedure, during or after manufacture of the core assembly.

Preferably the first winding may be applied by winding onto the core, wrap and end cap or end caps, or may be slid onto the core as a pre-made winding.

Preferably the at least one winding has provision for at least one electrical connection for that winding.

Preferably the at least one winding is separated from the wound yoke by the at least one end cap.

Preferably the at least one end cap also in part retains the wrap to, and about, the core.

In another aspect the present invention may be said to broadly consist in a method of manufacture of a core sub-assembly for an electromagnetic device, comprising or including the steps in any order of, Providing a core of first magnetically permeable material extending in a first direction, Applying a wrap of a first insulating material at least in part enclosing the core about its exterior surface, Connecting at least one end cap, of a second insulating material, to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, Applying at least one first winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained in the first direction by the inwardly presenting guide portion, Whereby the resulting core sub-assembly can be assembled by itself or with one or more other core sub-assemblies and at least one wound yoke on the outwardly presenting guide portion to form an electromagnetic device when appropriately connected and powered.

Preferably the at least one wound yoke of second magnetically permeable material is connected to the at least one end cap, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion.

Preferably the method includes the step of providing or making an electrical connection and/or mechanical connection between the core(s) and a reinforcement joiner.

In another aspect the present invention may be said to broadly consist in a core assembly for an electromagnetic device as described herein with reference to any one or more of the accompanying drawings.

In another aspect the present invention may be said to broadly consist in a method of manufacture of a core assembly for an electromagnetic device as described herein with reference to any one or more of the accompanying drawings.

In another aspect the present invention may be said to broadly consist in a kit of parts for a core assembly for an electromagnetic device as described herein with reference to any one or more of the accompanying drawings.

In another aspect the present invention may be said to broadly consist in a the use of a core assembly for an electromagnetic device in an electric or magnetic circuit as described herein with reference to any one or more of the accompanying drawings.

As used herein the term "and/or" means "and" or "or", or both.

As used herein "(s)" following a noun means the plural and/or singular forms of the noun.

The term "comprising" as used in this specification means "consisting at least in part of". When interpreting statements in this specification which include that term, the features, prefaced by that term in each statement, all need to be present, but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7).

The entire disclosures of all applications, patents and publications, cited above and below, if any, are hereby incorporated by reference.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements and features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred forms of the present invention will now be described with reference to the accompanying drawings in which;

Figure 1 Shows in isometric view a stack, in this case made from lengthwise strips of magnetically permeable material that are laminated to form a core,

Figure 2 Shows the stacked core of Figure 1 in end view, in this case the stack is formed from four packets of increasing width, each packet made up of laminated strips,

Figure 3 Shows in isometric view at (A) the end cap in isometric showing the outwardly presenting guide portion, and (B) the end cap in isometric showing the inwardly presenting guide portion and core pocket to form the bobbin, in this case suitable for a three core device,

Figure 4 Shows in isometric view the tube, interrupted in this case, to engage with the end pieces, to form the centre of the bobbin,

Figure 5 A) Shows isometric view the assembly of the core, with the tube, and end caps, and shows at B) in isometric view the completed bobbin assembly from Figure 5A,

Figure 6 Shows in isometric view the process and result of winding the completed bobbin and winding the core on to the bobbin,

Figure 7 Shows in isometric form the completed bobbins with cores attached and assembled in this case in a three core configuration,

Figure 8 Shows in plan view the reinforcement joiner for a three core configuration,

Figure 9 Shows the reinforcement joiner of Figure 8 in perspective side view,

Figure 10 Shows in isometric view the exploded assembly of the three core configuration and reinforcement joiners at each end,

Figure 11 Shows in close up isometric view the reinforcement joiners and its complimentary location in the end caps,

Figure 12 Shows in plan view Detail AA and the location of the reinforcement joiner against the stacked core,

Figure 13 Shows in plan view the location of the reinforcement joiner against the stacked core, and the locations of the connection of the core to the reinforcement joiner legs, in this case by welding,

Figure 14 Shows in exploded plan view the reinforcing pins,

Figure 15 Shows in isometric plan view the location of the reinforcing pins in the end caps,

Figure 16 shows in isometric view the connection of the wound yoke to the reinforcement joiner prior to winding onto the end caps,

Figure 17 shows in isometric view Detail BB from Figure 16 and the connection of the wound yoke start to the reinforcement joiner, and

Figure 18 shows in isometric end view the completed wound yoke for one end of the three leg configuration.

DETAILED DESCRIPTION OF THE INVENTION Preferred embodiments will now be described with reference to Figures 1 through 18.

The technology may be used to construct inductors, reactors, transformers, transresistors and filters where more than one core limb is required.

The core assembly 1 consists of an assembly of one core sub-assembly 3 or more core sub-assemblies 3. The core sub-assembly 3 starts as a core 4. In the preferred form the core is made from a lamination of thin strips 5 of the first magnetically permeable material, for example steel. The strips 5 are of varying width W as shown in Figure 2 to provide the desired core cross section. In one preferred form as shown the cross section is substantially circular. While a substantially circular cross section is shown, as best can be approximated from the laminated strips 5 and their thickness, any desirable cross section may be used. The strips 5 run in a first direction 7 as shown.

Applied to a first end 10 of the core 4 is an end cap 9 as shown in Figures 3A and 3B. The end cap 9 has a planar guide 11 extending radially outward on which there is an inwardly presenting guide portion 12, and an outwardly presenting guide portion 13. These present substantially as surfaces as shown, though are not continuous due to reinforcing webs. The end cap 9 on its inward side has a core pocket 26. As shown this is contoured for the external profile of the strips 5 of the core 4. However, it may also be less contoured, though this is less desirable. The end cap 9 also has a longitudinal aperture 21 as shown. This allows for compaction of the core pocket 26 when the winding is later applied, and also allows for potting or gluing compound to reach further into the core assembly or sub assembly when completed. The end cap 9 also has a provision 15 to connect to the wound yoke 14. In the form shown this is an interrupted protrusion from the outwardly presenting guide portion. A cap aperture 27 is also present through the planar guide from the outwardly presenting guide portion 13 through to the inwardly presenting guide portion 12 to allow the reinforcement joiner 17 to connect to the core 4 as described later.

The end cap 9 is made from an insulating material, and in the preferred form is injection moulded from plastic. In other forms the end cap 9 may be made from a ferrite or similar magnetically permeable material. Those skilled in the art will understand that any suitable forming technique can be used for these materials, for example depending on the number that need to be made then injection moulding or similar may be a suitable technique for mass production, but where only small numbers or single units are needed then machining or additive manufacturing such as three dimensional printing may be used.

An example of materials and techniques and frequencies for which they are suitable is tabled below. Application Plastic moulded end cap Magnetically permeable end cap Wound yoke Low frequency only Yes No Yes Low and high No Yes Yes frequency

Low frequency magnetically permeable materials such as silicon steels are generally suitable for frequencies up to 1kHz (kilohertz) and amorphous steels up to several tens of kHz. At higher frequencies such materials become very lossy, generate significant heat and become less magnetically permeable.

High frequency magnetically permeable materials such as ferrites and other ferrous compounds are generally suitable up to 100kHz and above. These materials have been formulated to minimise losses at higher frequencies and have good magnetic permeability characteristics. At lower frequencies such magnetically permeable materials as used for higher frequencies are effectively invisible. Thus in the case where a certain design may require a device to carry both low and high frequency currents, a magnetically permeable end cap made from a material suited to high frequencies, will effectively shield the wound yoke from such higher frequencies, while the wound yoke will treat lower frequencies if it is made from magnetically permeable material suited to lower frequencies.

The wound yoke may also be made from magnetically permeable tape designed for higher frequencies as any given design may require, or, a combination of magnetically permeable tapes or other materials to achieve the desired design performance.

The end cap 9 may perform any of the following functions, separately or combined as an end of the winding bobbin, Insulator between the winding 16, core 4 and wound yoke 14, spacer, stiffener and locator for adjacent core sub-assemblies 3, magnetic path in high frequency designs (if formed from higher frequency magnetically permeable material), and a former or mounting provision for the wound yoke 14.

A wrap 8 of insulating material as shown in Figures 4A and 4B, is also used to wrap the core 4 as shown in Figures 5A and 5B. The wrap 8 is of thin, planar construction and wrapped around the core 4. Alternatively it may be extruded or injection moulded as needed. In the assembly process of the core the end cap 9 at least in part traps the wrap 8 between the outside of the core 4 and the inside of the core pocket 26. This the core pocket 26 may have some tolerance to allow for this, or the wrap may be sufficiently thin, as a sheet for example, to slip in, with only minor deformation of the core pocket. The wrap 8 also has the longitudinal aperture 21 to allow for compaction, and permeation of the potting or gluing compound.

The wrap 8 is located about the core 4 and then the end cap 9 is slid into place. As shown in Figures 5A and 5B there are two end caps 9 that locate on the first end 10 and second end 28 to encase the core 4. The result is a bobbin that encases the core 4.

The Insulating materials for the end caps 9 and the wrap 8 may vary as they will be specific to the specific application governed by electrical and thermal considerations.

The resulting bobbin 29 shown in Figure 6A can then be wrapped with one or more windings 16. In the known way these can be wound onto the bobbin between the two inwardly presenting guide portions 12 resulting in a winding 16 as shown in Figure 6B. Alternatively, before, or as part of applying the end cap 9 to the second end 28, a preformed winding is slide into place, and the second end cap 9 joined. Other alternatives, and assembly orders and techniques, also present themselves and fall under the invention.

The core sub-assemblies 3 are then, if more than one is needed, brought together as shown in Figure 7A. The end caps 9 are so shaped so that their periphery 22 where they meet each other, is complimentary to reinforce the structure. A planar periphery 22 engagement is shown but there may be other forms also that can be used at least where neighbouring core sub-assemblies 3 meet.

A reinforcement joiner 17 as shown in Figure 8 and 9 has legs 30 that correspond to the number of core sub-assemblies 3 being brought together. The reinforcement joiner 17 when located into the cap apertures 27 in assembly to the assembled core sub assemblies as shown in Figure 10, brings the legs 30 into contact with the core. These can be welded or otherwise mechanically, and optionally electrically, connected to core 4 they contact, as further shown in Figures 11 through 13 for a three core-subassembly core assembly.

In some preferred forms of the invention there may be a desire or need to further stiffen the mechanical connections of the windings and cores. In these situations pins 23 for example may be driven into complimentary pockets 31 in the end cap 9, as shown in Figures 14 and 15. These pins will force down internally into the winding, displacing it and tightening the overall core sub-assembly and thus the core assembly 1.

Once the assembly of the core sub-assemblies 3, or single core sub-assembly 3 is completed then the wound yokes 14 of a second magnetic permeable material 24 (whether the same of different to first magnetically permeable material) may be applied as shown in Figures 16 through 18. In one method the wound coupling coil 14 has one end connected to, for example the reinforcement joiner 17, for example by welding or other acceptable method. The second magnetically permeable material 24 as shown is a thin strip. The thin strip may then be wound onto the provisions 15, aided by the outwardly presenting guide portion 13.

In one method the partially assembled core assembly as shown in Figure 16, may be held and then rotated in direction 25 to wind on and form the yoke 14. The provisions 15 and guide portion 13, and any other guide as needed, form, with the winding a tightly wound coupling coil 14 as shown in Figure 18 (individual layers of the coil not shown). The amount wound on may be a standard amount that is the most needed for the application. In other forms, the amount wound on is the exact amount needed for the inductance and other characteristics of the required electromagnetic device. The amount needed may be a desired diameter or length. This tuning may be performed in situ by energising the windings and material 24 as it is wound on until the desired characteristics are met and then the material 24 is cut and finished. The holding may be by the exterior periphery of the end caps 9 or by the reinforcement joiners 17 , as visible in Figure 16. The inductance characteristic relates to the amount of strip steel material 24 wound at the ends.

Alternatively the wound yoke 14 may be pre-made in a similar method and then slid onto the provisions 15 until it is hard against the outwardly presenting guide portion 13. In this way the thickness of the planar guide and thus the separation of the yoke 14 from the core 4 and the winding(s) 16 may be used to tune the device. In other forms the relative distance in the first direction 7 between the yoke 14 and the core 4 and or winding 16 may be achieved by how far the yoke 14 is pushed onto the end cap or provisions. The provisions may be longer to allow this relative positioning. Or course there may also be a mixture of these tuning methods employed. At this point the wound yoke 14 could be potted or otherwise glued in place.

Tuning the wound yoke may be achieved as described. In doing so the windings 16 are themselves are energised but not necessarily the yoke 14 itself. Measurements of the windings 16 determine when the device 1 is correctly tuned. In the first case, the wound yoke 14 is wound until the desired characteristic is achieved. In the second case, the pre wound yoke is pressed onto the provisions 15 axially, until the desired tuning is achieved.

The first magnetically permeable material for the core and the second magnetically permeable material for the wound yoke material may be the same however they may also be different magnetically permeable materials as required to optimise the performance characteristic and cost of the device.

As shown in Figures 16 and 17 there are wound coils 14 at both ends of the core assembly.

Thereafter the core assembly 1 may be potted in a compound, or otherwise glued to give good mechanical and insulative properties.

While the invention relates to a device with any number of cores (2 or more) in a transformer or reactor, it has been applied initially to devices with 3 cores such as 3-phase power devices.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention.

Claims (22)

1. A core assembly for an electromagnetic device, comprising or including, A core sub assembly of, a. A core of first magnetically permeable material, extending in a first direction, b. A wrap of a first insulating material at least in part enclosing the core about its exterior surface, c. At least one end cap, of a second material, connecting to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, d. At least one winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained in the first direction by the inwardly presenting guide portion, At least one wound yoke of second magnetically permeable material, applied to at least one core assembly, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion(s), An electrical connection and/or mechanical connection between the core subassembly(s) and a reinforcement joiner, Whereby the resulting core assembly of one or more core sub-assemblies can be used to form an electromagnetic device when appropriately connected and powered.

2. The core assembly of claim 1 wherein the core is made from a laminate of magnetically permeable material.

3. The core assembly of either of claims 1 or 2 wherein the core is substantially circular, square or rectangular in cross section and is a full length core or comprises multiple shorter core(s).

4. The core assembly of any one of claims 1 to 3 wherein there are two end caps, one for each end of the core.

5. The core assembly of any one of claims 1 to 4 wherein the second material is either an insulating material and/or a magnetically permeable material.

6. The core assembly of any one of claims 1 to 5 wherein the end cap is shaped, at least on part of its periphery between the inwardly presenting guide portion and the outwardly presenting guide portion, to be complimentary to an end cap of a neighbouring core sub-assembly.

7. The core assembly of any one of claims 1 to 6 wherein there are two reinforcement joiners, one for each end of the core assembly and wherein the reinforcement joiner is made from a magnetically non-permeable material.

8. The core assembly of any one of claims 1 to 7 wherein the reinforcement joiner is at least mechanically, if not electrically also, connected to the end of the core, or respective end of each core.

9. The core assembly of any one of claims 1 to 8 wherein there are two wound yokes, one for each end of the core assembly.

10. The core assembly of any one of claims 1 to 9 wherein the wound yoke is of a dimension such as length or diameter to achieve the desired magnetic coupling characteristic.

11. The core assembly of any one of claims 1 to 10 wherein the wound yoke is positioned relative to the core and or the winding in the first direction either due to the thickness of the planar guide, or the positioning of the end cap to achieve the desired magnetic coupling characteristic.

12. The core assembly of any one of claims 1 to 11 wherein the at least one winding forms one or more layers of non-magnetically permeable, electrically conductive material.

13. The core assembly of any one of claims 1 to 12 wherein the at least one winding has provision for at least one electrical connection for that winding.

14. The core assembly of any one of claims 1 to 13 wherein there are two or more windings and wherein there is another wrap, or other insulation between each of the two or more windings.

15. The core assembly of any one of claims 1 to 14 wherein the at least one winding can be formed in situ by winding onto the core, wrap and end cap(s), or may be pre-formed and pressed onto the assembly of the core and wrap, and or end cap.

16. A method of manufacture of a core assembly for an electromagnetic device, comprising or including the steps in any order of, Forming a core sub-assembly from the steps of, a. Providing a core of first magnetically permeable material extending in a first direction, b. Applying a wrap of a first insulating material at least in part enclosing the core about its exterior surface, c. Connecting at least one end cap, of a second insulating material, to a first end of the core and wrap, the at least one end cap having a planar guide extending radially therefrom, the planar guide having an inwardly presenting guide portion and an outwardly presenting guide portion, d. Applying at least one first winding, of an electrically conductive material, about the core and wrap, the at least one winding being at least in part contained in the first direction by the inwardly presenting guide portion, Connecting to at least one core sub-assembly, at least one wound yoke of second magnetically permeable material to the at least one end cap, the at least one wound yoke being located and retained at least in part by a provision on the outwardly presenting guide portion, Providing or making an electrical connection and/or mechanical connection between the core(s) and a reinforcement joiner, Whereby the resulting core assembly can be used as an electromagnetic device when appropriately connected and powered.

17. The method of claim 16 wherein the method includes the step of assembling multiple core sub-assemblies together to which the at least one wound yoke is, or can be applied.

18. The method of either claim 16 or 17 wherein the method includes the step of applying another end cap to the other end of the core sub-assembly and wherein there is a wound yoke at each end of an assembly of the core-sub-assembly or subassemblies.

19. The method of any one of claims 16 to 18 wherein the wound yoke is formed by one continuous strip of the second magnetically permeable material by winding in a continuous spiral.

20. The method of any one of claims 16 to 19 wherein the wound yoke can be formed in situ on the end cap(s), or may be pre-formed and pressed onto the end cap(s).

21. The method of any one of claims 16 to 20 wherein the wound yoke is wound to the required length or diameter to achieve the desired magnetic coupling characteristic, or is corrected to the required length or diameter as part of a tuning procedure, during or after manufacture of the core assembly, and or is adjusted in the first direction relative the core and winding either by the relative position of the end cap(s), the thickness of the planar guide as part of a tuning procedure, during or after manufacture of the core assembly.

22. The method of any one of claims 16 to 21 wherein the first winding may be applied by winding onto the core, wrap and end cap or end caps, or may be slid onto the core as a pre-made winding.