GB2562893A

GB2562893A - Rotor core assembly

Info

Publication number: GB2562893A
Application number: GB1805857.8A
Authority: GB
Inventors: Barker Jon
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2017-04-14
Filing date: 2018-04-09
Publication date: 2018-11-28
Anticipated expiration: 2038-04-09
Also published as: DE102018205273A1; GB2562893B; GB201805857D0; GB201706045D0

Abstract

A rotor core assembly 100 for an electric machine, the assembly comprising: a rotor core 120 comprising at least one slot 140 receiving a magnet block 160 and a least one lamina 180; wherein the lamina received within slot is arranged to position the block within said slot, wherein the block is connected to a surface of the slot by the lamina, said surface being radially distal to the axis of rotation (A, fig 1). The lamina may be positioned adjacent to a single face, two faces, three faces, four faces or five faces of the magnet block, or may be continuous as to wrap around a plurality of faces of the block. The magnet block may be cuboid. The lamina may comprise one of an adhesive, polymer, adhesive composite, polymer composite, or a combination of both. The lamina may also comprise protrusions (182, fig 7b) or perforations (184, fig 7d) of a repeating pattern. The lamina may be uniform in thickness in the range of 25µm to 200µm. The lamina may be applied to the block before inserting into the slot, and the rotor rotated to urge the magnet and lamina into contact with the radially surface. The assembly maybe used in a vehicle.

Description

(54) Title ofthe Invention: Rotor core assembly

Abstract Title: A rotor core assembly with lamina to position a magnet block within the rotor core at a radially distal surface to axis of rotation (57) A rotor core assembly 100 for an electric machine, the assembly comprising: a rotor core 120 comprising at least one slot 140 receiving a magnet block 160 and a least one lamina 180; wherein the lamina received within slot is arranged to position the block within said slot, wherein the block is connected to a surface of the slot by the lamina, said surface being radially distal to the axis of rotation (A, fig 1). The lamina may be positioned adjacent to a single face, two faces, three faces, four faces or five faces of the magnet block, or may be continuous as to wrap around a plurality of faces ofthe block. The magnet block may be cuboid. The lamina may comprise one of an adhesive, polymer, adhesive composite, polymer composite, or a combination of both. The lamina may also comprise protrusions (182, fig 7b) or perforations (184, fig 7d) of a repeating pattern. The lamina may be uniform in thickness in the range of 25pm to 200pm. The lamina may be applied to the block before inserting into the slot, and the rotor rotated to urge the magnet and lamina into contact with the radially surface. The assembly maybe used in a vehicle.

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ROTOR CORE ASSEMBLY

TECHNICAL FIELD

The present disclosure relates to a rotor core assembly. Particularly, but not exclusively, the disclosure relates to a rotor core assembly for an electric machine. Aspects of the invention relate to a rotor core assembly, a vehicle having a rotor core assembly, and to a method of assembling a rotor core assembly.

BACKGROUND

Current electric machines of electric and hybrid-electric vehicles typically have internal permanent magnets bonded to a rotor core of the electric machine using a liquid (wet) adhesive. The use of such adhesive in electric machines presents a number of manufacturing problems, typically the inconsistent positioning of the internal permanent magnets within the rotor core which contributes to rotor unbalance, adhesive bleed-out in between laminations of the rotor core, adhesive bleed-out from the end of a pocket or slot during insertion of a magnet into the pocket or slot, uncertainty as to which surfaces of the magnet are provided with the adhesive, and a number of issues relating to maintenance and cleaning of the electric machines.

It is an aim of the present invention to address one or more of the aforementioned disadvantages.

SUMMARY OF THE INVENTION

Aspects of the invention provide a rotor core assembly for an electric machine, a vehicle comprising such a rotor core assembly, and a method of assembling a rotor core assembly, as claimed in the appended claims.

According to an aspect of the invention, there is provided a rotor core assembly for an electric machine. The rotor core assembly has a rotor core comprising at least one slot for receiving a magnet block and at least one lamina. At least one lamina is received within the at least one slot of the rotor core and arranged to position a magnet block within said slot.

According to another aspect of the invention, there is provided a magnet block for an electric machine. The magnet block is adjacent to a lamina.

According to another aspect of the invention, there is provided a rotor core assembly for an electric machine, the rotor core assembly having an axis of rotation comprising:

a rotor core comprising at least one slot for receiving a magnet block and at least one lamina;

a magnet block received within the at least one slot; and at least one lamina received within the at least one slot of the rotor core and arranged to position the magnet block within said slot, wherein the magnet block is connected to a surface of the slot by the lamina, said surface being radially distal to the axis of rotation.

By using a lamina within a slot of the rotor core to position a magnet block within said slot, and avoiding using a wet adhesive, a consistent position of the magnet block within the slot can be achieved and rotor unbalance reduced. A consistent position of the magnet block within the slot and reduction of rotor unbalance is achieved because the lamina will remain in a desired position and hence, keep the magnet block in a desired position so that the mass distribution of the magnet block in the rotor core is consistent.

Using a lamina to position each of a plurality of magnet blocks of the rotor core assembly within each corresponding slot will consistently position each magnet block and, thus, reduce rotor unbalance.

In addition, adhesive bleed-out between components of the electric machine and out from the end of the slot is avoided because the lamina will not run onto, or spill onto, undesired surfaces of the magnet block or rotor core assembly when provided within a slot of the rotor core.

Use of a lamina provides further flexibility and certainty in relation to which surfaces of the magnet block the lamina is adjacent because the lamina can be controlled and provided in a slot more reliably and easily than liquid adhesive.

Furthermore, use of a lamina provides greater flexibility in the maintenance and cleaning processes used on the rotor core assembly because use of liquid adhesive, that can spill onto and bleed-out onto undesired surfaces of the rotor core assembly and interact with equipment of maintenance and cleaning processes, is avoided.

The at least one lamina may be positioned adjacent a single face of the magnet block.

Use of the at least one lamina adjacent a single side of the magnet block allows the magnet block to be biased against one side of the slot of the rotor core, which reduces rotor unbalance by providing an even mass distribution within the rotor core.

Optionally, the at least one lamina may be positioned adjacent one of the following: two faces of the magnet block; three faces of the magnet block; four faces of the magnet block; and five faces of the magnet block.

Positioning a lamina adjacent multiple sides of the magnet block within a slot of the rotor core provides a stable and consistent positioning of the magnet block in the slot. This helps to reduce rotor unbalance.

The at least one lamina may be positioned adjacent opposing faces of the magnet block to centralise the magnet block in the slot.

Positioning a lamina adjacent opposing faces of the magnet block increases the stability of the magnet block in the slot and, thus, provides a consistent magnet position in the rotor core and helps reduces rotor unbalance.

Optionally, the at least one lamina is a continuous lamina so as to wrap around a plurality of faces of the magnet block.

Optionally, the rotor core comprises an upper surface and the magnet block comprises a deepest face. The deepest face is positioned furthest from the upper surface compared to the other faces of the plurality of faces. At least part of the at least one lamina lies adjacent the deepest face.

Wrapping around of the lamina achieves increased stability of the magnet block within the slot of the rotor core, and subsequently, reduces rotor unbalance.

The magnet block may be a cuboid.

The slot may have a shape corresponding to the shape of the magnet block.

Optionally, at least a portion of the at least one lamina may be moulded to the rotor core to aid retention of a magnet block in the slot. That is, at least a portion of the at least one lamina may be deformed to mould to the shape of the rotor core to aid retention of a magnet block in the slot.

Optionally, the rotor core may be formed from one or more laminations. Each slot of the rotor core may be formed from one or more laminations.

Optionally, at least a portion of the at least one lamina may be moulded to one or more laminations of the rotor core that form the slot. That is, at least a portion of the at least one lamina may be deformed to mould to the shape of one or more laminations of the rotor core that form the slot. Optionally, the one or more laminations forming the slot may be separated from one another by gaps. The lamina may be moulded into the gaps between the laminations. That is, at least a portion of the at least one lamina may be deformed to mould into and at least partially fill the gaps between the laminations.

Moulding (or deforming) of the at least one lamina to the rotor core, and, more specifically, to one or more laminations of the rotor core increases the stability of the magnet block in the slot whilst also providing a consistent position of the magnet block in the slot, helping to reduce rotor unbalance.

The moulding of at least a portion of the at least one lamina may occur after the lamina has been received by a slot of the rotor core.

The at least one lamina may comprise one of the following: an adhesive, a polymer, an adhesive composite, a polymer composite, and a combination of an adhesive and a polymer.

Optionally, the at least one lamina may comprise fold lines to aid in folding of the at least one lamina around the magnet block.

Fold lines in the lamina increase yielding of the at least one lamina to the magnet block, that is, the extent of wrapping of the lamina around the magnet block is increased. Indeed, fold lines allow the lamina to more easily mould, or deform, to the shape of the magnet block. Fold lines help to increase the proportion of the lamina that is in contact with the magnet block and, thus, result in a more consistent positioning of the magnet block within the slot by the lamina. Rotor unbalance is decreased by having a more consistent position of each of the magnet blocks of the rotor core since a more even distribution of mass is provided.

The at least one lamina may have a thickness in the range from 25 pm to 200 pm. The at least one lamina may have a thickness in the range from 50 pm to 175 pm. The at least one lamina may have a thickness in the range from 75 pm to 150 pm. The at least one lamina may have a thickness in the range from 100 pm to 150 pm. The at least one lamina may have a thickness of 100 pm.

Optionally, the at least one lamina may comprise a perforation.

Use of a perforation in the lamina helps to retain the magnet block within the slot of the rotor core whilst also helping to consistently position the magnet block in the slot in order to reduce rotor unbalance.

The at least one lamina may comprise a plurality of perforations arranged in a repeating pattern.

Optionally, the at least one lamina may comprise a protrusion on one side of the lamina.

Use of a protrusion in the lamina helps to retain the magnet block within the slot of the rotor core by creating a point of increased friction between the magnet block and the lamina, whilst also helping to consistently position the magnet block in the slot in order to reduce rotor unbalance.

Optionally, a protrusion of the lamina may be located on a side of the lamina adjacent the magnet block.

The at least one lamina may comprise a plurality of protrusions arranged in a repeating pattern.

Optionally, the at least one lamina is uniform in thickness.

The rotor core assembly may be part of an electric machine.

The electric machine may be a three phase internal permanent magnet synchronous machine.

According to another aspect of the present invention, there is provided a vehicle comprising the rotor core assembly.

According to a further aspect of the invention, there is provided a method of assembling a rotor core assembly of an electric machine, the method comprising inserting a lamina within a slot of a rotor core such that the lamina is arranged to position a magnet block within said slot.

According to another aspect of the invention, there is provided a method of assembling a magnet block of an electric machine. The method may comprise abutting a magnet block and a lamina.

A method of assembling a rotor core assembly of an electric machine, the method comprising:

inserting a lamina within a slot of a rotor core;

inserting a magnet block into the slot of the rotor core; such that the lamina is arranged to position the magnet block within the slot; and rotating the rotor core to about an axis of rotation to urge the magnet and lamina into contact with a radially distal surface of the slot in order to connect the magnet and lamina to the radially distal surface of the slot..

Assembling a rotor core assembly by inserting a lamina within a slot of a rotor core so that the lamina is arranged to position a magnet block within the slot provides a consistent position for the magnet block in the slot and therefore reduces rotor unbalance. Rotation of the rotor core also provides for consistent positioning of the magnet block as the radial distal surface of the magnet block is urged towards the radial distal surface of the slot.

Use of a lamina also avoids adhesive bleed-out in between laminations of the rotor core and also from the end of the slot during insertion of the magnet block into the slot because a wet adhesive is not used to hold the magnet block in the rotor core. A wet adhesive can bleed-out and also be inconsistently applied to the slot or magnet block of the rotor core which creates uneven mass distribution of rotor core and in doing so contributes to rotor unbalance.

In addition, use of a lamina allows flexibility in choosing the surfaces of the magnet block that the lamina is positioned against in order to consistently position the magnet block within the slot because a lamina is more controllable than a wet adhesive and is therefore more reliable and easier to use than a wet adhesive.

Inserting a lamina within the slot of the rotor core to position the magnet block within the slot also increases the flexibility of maintenance and cleaning equipment that can be used on the rotor core assembly because use of a wet adhesive, that can spill onto and bleed-out onto undesired surfaces of the rotor core assembly and interact with the maintenance and cleaning equipment, is avoided.

The method of assembling a rotor core assembly may comprise applying the lamina to one of the magnet block or the slot prior to inserting the magnet block into the slot.

Optionally, the method may comprise applying a lamina to the magnet block prior to inserting the lamina into the slot.

Optionally, the method may comprise applying the lamina to the slot prior to inserting the magnet block into the slot.

Alternatively, the method of assembling a rotor core assembly may comprise arranging the lamina between the magnet block and the rotor core prior to inserting the lamina, such that upon insertion of the magnet block into the slot the lamina wraps around two or more faces of the magnet block to provide a consistent magnet block position in the slot.

Optionally, the method of assembling a rotor core assembly may comprise deforming at least a portion of the lamina after the lamina has been inserted into the slot of the rotor core.

Optionally, the method of assembling a rotor core assembly may comprise pre-folding the lamina prior to inserting the lamina in order to aid in wrapping of the lamina around two or more faces of the magnet block upon insertion of a magnet block into the slot.

The lamina may be pre-folded into a truncated shape that corresponds to the shape of the slot of the rotor core.

Pre-folding of the lamina helps the lamina to mould to the shape of the magnet block, and, thus, allows the lamina to wrap around two or more faces of the magnet block more easily which increases the level of retention of the magnet block in the slot.

Optionally, the method of assembling a rotor core assembly may comprise curing the lamina after inserting the lamina into the slot.

Optionally, the method of assembling a rotor core assembly may comprise curing the rotor core assembly after inserting the magnet block into the slot.

The curing the lamina may comprise heating the lamina. The lamina may be heated by induction heating of the rotor core.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a rotor core assembly according to an embodiment of the invention.

Figure 2 is a perspective view of an electric machine according to an embodiment of the invention.

Figure 3 is a cross sectional view of a rotor core assembly according to an embodiment of the invention.

Figure 4 is a flow chart of a method according to an embodiment of the invention.

Figure 5A is a perspective view of component parts of a rotor core assembly according to an embodiment of the invention.

Figure 5B is a further perspective view of the component parts of the rotor core assembly of Figure 5A.

Figure 5C is a further perspective view of the component parts of the rotor core assembly of

Figures 5A and 5B.

Figure 6 is a perspective view of a lamina in accordance with an embodiment of the invention.

Figure 7A is a perspective view of a lamina in accordance with an embodiment of the invention.

Figure 7B is a perspective view of a lamina in accordance with a further embodiment of the invention.

Figure 7C is a perspective view of a lamina in accordance with a further embodiment of the invention.

Figure 7D is a perspective view of a lamina in accordance with a further embodiment of the invention.

Figure 8 is a perspective view of a lamina in accordance with a further embodiment of the invention.

Figure 9 is a side view of a vehicle including a rotor core assembly in accordance with a further embodiment of the invention.

DETAILED DESCRIPTION

Figure 1 is a perspective view of a rotor core assembly 100. The rotor core assembly 100 has a rotor core 120. The rotor core 120 has at least one slot 140 for receiving a magnet block 160 and at least one lamina. The rotor core assembly 100 also has a magnet block 160 received within the at least one slot 140. At least one lamina (not shown) is received within the at least one slot 140 of the rotor core 120 and is arranged to position the magnet block 160 within the slot 140. The rotor core 120 of Figure 1 has sixteen slots 140. However, the rotor core 120 may have more than sixteen slots or fewer than sixteen slots. The rotor core assembly 100, in use, is rotatable about an axis of rotation A-A.

Each slot 140 of rotor core 120 has a magnet block 160 and a lamina.

Using a lamina within a slot 140 of the rotor core 120 to position the magnet block 160 within the slot 140, and avoiding using a wet adhesive, provides a consistent position of the magnet 160 within the slot 140 which reduces rotor unbalance because the lamina will remain in a desired position when provided within the slot 140 of the rotor core 120. Using a lamina within each slot 140 of the rotor core 120 to position each magnet block 160 of the rotor core 120 will consistently position each magnet block 160 and, thus, achieve an even mass distribution of magnet blocks and in doing so reduce rotor unbalance.

In addition, adhesive bleed-out between components of the rotor core assembly 100 and out from the end of each slot 140 is avoided because the lamina 180 will not run onto, or easily spill onto, undesired surfaces of the magnet block 160 or other surfaces of the rotor core assembly 100 when provided within each slot 140 of the rotor core 120.

Use of the lamina provides further flexibility and certainty in relation to which surfaces of the magnet block 160 the lamina is adjacent because the lamina can be controlled and provided in a slot 140 more reliably and easily than wet adhesive.

Furthermore, use of the lamina provides greater flexibility in the maintenance and cleaning processes that can be used on the rotor core assembly 100 because use of liquid adhesive, that can spill onto and bleed-out onto undesired surfaces of the rotor core assembly 100 is avoided.

It is well understood that an electric machine can be constructed from an outer stator component having current-carrying windings that produce a magnetic field and an inner rotor component having integrated permanent magnets which are influenced by the magnetic field of the stator, resulting in rotation of the rotor component.

The rotor core assembly 100 of Figure 1 may be part of an electric machine.

Figure 2 is a perspective view of an electric machine 300. The electric machine 300 has a stator 320. The electric machine 300 also has a rotor 350. The rotor 350 is positioned inside stator 320. The rotor 350 has a rotor core assembly 200 and a shaft 250. The shaft 250 is connected to the rotor core assembly 200. The rotor core assembly 200 is similar to the rotor core assembly 100 described in relation to Figure 1, yet, the rotor core assembly 200 of Figure 2 has six slots 140.

The electric machine 300 is a three phase internal permanent magnet synchronous machine.

Figure 3 shows a cross sectional view along line B-B of the rotor core assembly 100 of Figure 1. Figure 3 shows the arrangement of the rotor core assembly 100 of Figure 1 in more detail.

The lamina 180 is positioned adjacent opposing faces 161, 162 of magnet block 160 to centralise the magnet block 160 in the slot 140. In more detail, lamina 180 is positioned adjacent the broadest opposing faces 161, 162 of magnet block 160. The lamina 180 is a continuous lamina so as to wrap around a plurality of faces of the magnet block 160, including the broadest opposing faces 161, 162. The rotor core 120 has an upper surface 122. The slot 140 has an opening in the upper surface 122.The magnet block 160 has a deepest face 166 positioned furthest from the upper surface 122 compared to the other faces of the plurality of faces when the magnet block 160 has been inserted into the slot 140, and the continuous lamina is also located adjacent this deepest face. Thus, lamina 180 is positioned adjacent three faces of the magnet block 160.

By using the lamina 180 to position the magnet block 160 within the slot 140 of the rotor core 120 a consistent position of the magnet block 160 in the slot 140 is achieved. The magnet block 160 has a consistent and stable position in the slot 140 by positioning the lamina 180 adjacent three faces of the magnet block 160. A consistent position of the magnet block 160 helps to reduce rotor unbalance.

Whilst Figure 3 shows the lamina 180 positioned adjacent three faces of the magnet block

160, the lamina 180 may be positioned adjacent one of the following: a single face of the magnet block 160, two faces of the magnet block 160, four faces of the magnet block 160, and five faces of the magnet block 160.

The magnet block 160 is a cuboid. The slot 140 has a shape corresponding to the shape of the magnet block 160.

The magnet block 160 is positioned sub-flush in relation to the upper surface 122 of rotor core 120. Alternatively, the magnet block 160 may be positioned flush in relation to the upper surface 122 of the rotor core 120, or positioned protruding out of slot 140 and above the upper surface 122 of the rotor core 120.

The slot 140 of rotor core assembly 100 of Figure 3 is blind, but, alternatively, slot 140 could be open-ended.

The lamina 180 may comprise one of the following: an adhesive, a polymer, an adhesive composite, a polymer composite, and a combination of an adhesive and a polymer.

The lamina 180 may be moulded to the rotor core 120 to aid retention of the magnet block 160 in the slot 140. In other words, the lamina 180 may be deformed to mould to the shape of the rotor core 120 to strengthen the bond between the lamina 180 and the rotor core 120 and consequently, aid retention of the magnet block 160 in the slot 140. For example, the lamina 180 may be deformed to mould to the shape of the slot 140 of the rotor core 120.

Figure 4 illustrates a flow chart of a method of assembling the rotor core assembly 100 of an electric machine. The method 400 comprises inserting 420 a lamina 180 within a slot 140 of the rotor core 120. The method further comprises inserting 440 a magnet block 160 into the slot 140 of the rotor core 120 such that the lamina 180 is arranged to position the magnet block 160 within the slot 140. The method further comprises rotating 460 the rotor core assembly 100. The rotor core assembly 100 is rotated about its axis of rotation A-A. It will be appreciated that such rotation urges the radially distal surface of the magnet block 160 towards the radially distal surface of the slot 140. This ensures consistent mass distribution of the magnet blocks 160.

Using a lamina 180 within a slot 140 of the rotor core 120 to position the magnet block 160 within the slot 140, and avoiding using a wet adhesive, provides a consistent position of the magnet 160 within the slot 140 which reduces rotor unbalance because the lamina will remain in a desired position when provided within the slot 140 of the rotor core 120. Thus, an even distribution of mass of the rotor core 120 is achieved. Using a lamina 180 within each slot 140 of the rotor core 120 to position each magnet block 160 of the rotor core 120 will consistently position each magnet block 160 and, thus, also reduce rotor unbalance.

Use of the lamina 180 provides further flexibility and certainty in relation to which surfaces of the magnet block 160 the lamina 180 is adjacent because the lamina 180 can be controlled and provided in a slot 140 more reliably and easily than wet adhesive.

Furthermore, use of the lamina 180 provides greater flexibility in the maintenance and cleaning processes that can be used on the rotor core assembly 100 because use of liquid adhesive, that can spill onto and bleed-out onto undesired surfaces of the rotor core assembly 100 and interact with equipment of the maintenance and cleaning processes, is avoided.

The inserting 440 of the magnet block 160 into the slot 140 may occur at the same time as the inserting 420 of the lamina 180 into the slot 140.

In a first variation, the method 400 comprises arranging the lamina 180 between the magnet block 160 and the rotor core 120 prior to inserting 440 the magnet block 160 and prior to inserting 420 the lamina 180, such that upon insertion of the magnet block 160 into the slot 140 the lamina 180 wraps around two or more faces of the magnet block 160 to provide a 14 consistent magnet block position in the slot 140 and reduce motor unbalance, illustrated by

Figures 5A to 5C.

In a second variation, the method 400 comprises applying the lamina 180 to the magnet block 160 prior to inserting 440 the magnet block 160 into the slot 140.

As a slight alternative to the first and second variations, in a third variation, the method comprises applying lamina 180 to the slot 140, and, in doing so, inserting 420 the lamina 180 into the slot 140, prior to inserting 440 the magnet block 160 into the slot 140. In this way, the lamina 180 is inserted into the slot 140 before the magnet block 160 is inserted into the slot 140.

The method 400 may comprise pre-folding the lamina 180, prior to inserting 420 the lamina 180, in order to aid in wrapping of the lamina 180 around two or more faces of the magnet block 160 upon insertion 440 of the magnet block 160 into the slot 140.

The method 400 may additionally comprise curing the lamina 180 after inserting 420 the lamina 180 into the slot 140. However, curing the lamina 180 is an optional method step. Curing the lamina 180 can either be carried out by placing the assembled rotor core assembly 100 into a curing oven or through induction heating of the rotor core assembly 100. As a slight variation, curing the lamina 180 may cure the whole rotor core assembly 100 after inserting 440 the magnet block 160 into the slot 140.

The method 400 may comprise rotating 460 the rotor core assembly 100 during curing of the lamina 180.

Figure 5A is a perspective view of component parts of the rotor core assembly 100. Figure 5A illustrates the arrangement of the magnet block 160, the lamina 180, the slot 140 and the rotor core 120 of the rotor core assembly 100 corresponding to simultaneous inserting 420 and inserting 440 of method 400. The lamina 180 is arranged between the magnet block 160 and the slot 140 of the rotor core 120. The lamina 180 has uniform thickness.

The lamina 180 is arranged substantially perpendicular to the length of the magnet block 160. The lamina 180 is aligned with the slot 140 such that upon insertion of the magnet block 160 into the slot 140 (in a direction illustrated by arrow A) the lamina 180 will wrap around two opposing faces 161, 162 of the magnet block 160 and the deepest face 166 of the magnet block 160 to provide a consistent magnet block position in the slot 140. The lamina 180 may be aligned to either partially or wholly cover the slot 140.

The magnet block 160 is a cuboid. The magnet block 160 is arranged lengthways in order to be inserted into the slot 140 of the rotor core 120. The slot 140 has a shape corresponding to the shape of the magnet block 160. Although in Figure 5A the magnet block 160 is arranged above the lamina 180 and the lamina 180 is arranged above the rotor core 120, this arrangement can be reversed so that the rotor core 120 is arranged above the lamina 180 and the lamina 180 is arranged above the magnet block 160.

Figure 5B is a further perspective view of the component parts of the rotor core assembly 100 of Figure 5A. Figure 5B illustrates the positioning of the magnet block 160 and the lamina 180 during the inserting 420, 440 of both the lamina 180 and the magnet block 160 into the slot 140. Figure 5C is a further perspective view of the component parts of the rotor core assembly 100 of Figures 5A and 5B.

Figure 5C illustrates the wrapping of the lamina 180 around the magnet block 160 such that the lamina 180 is positioned adjacent opposing faces 161, 162 of the magnet block 160 and the deepest face 166 of the magnet block 160.

In an alternative embodiment, the lamina 180 can be dimensioned such that it has a size and shape that is approximately the same as that of one of the opposing faces 161,162 of the magnet block 160. In such an embodiment, the lamina 180 is positioned adjacent a face of the magnet block 160 which is radially distal to the axis of rotation of the rotor core assembly 100. It will thus be appreciated that the lamina 180 is this positioned between the radially distal face of the magnet block 160 and the radially distal face of the slot 140.

Figure 6 is a perspective view of the lamina 180. The lamina 180 has two fold lines 185 arranged widthways across the lamina 180. The fold lines 185 aid in folding of the lamina

180 around the magnet block 160.

Alternatively, the lamina 180 may have a single fold line or three or more fold lines. The fold lines may be arranged lengthways across the lamina, or, in any direction across the lamina. In addition, the fold lines may form a grid or a diagonal criss-cross pattern.

The fold lines 185 in the lamina 180 increase yielding of the at least one lamina 180 to of the magnet block 160, that is, the extent of wrapping of the lamina 180 around the magnet block is increased. Indeed, the fold lines 185 allow the lamina 180 to more easily mould to the shape of the magnet block 160. The fold lines 185 help to increase the proportion of the lamina 180 that is in contact with the magnet block 160 and, thus, result in a more consistent positioning of the magnet block 160 within the slot 140 by the lamina 180. Rotor unbalance is decreased by having a more consistent position of the magnet block 160 in the slot 140 because each magnet block 160 of the rotor core 120 can be consistently positioned using a lamina 180 such that the rotor core 120 has even mass distribution.

The fold linesl 85 may also aid in the inserting 420 of the lamina 180 into the slot 140 of method 400 either when the lamina 180 is applied to one of the magnet block 160 or the slot 140 before inserting 440 the magnet block into the slot 140, or, when the lamina 180 is inserted 420 into the slot 140 at the same time as the magnet block 160 is inserted 440 into the slot 140.

Figure 7A is a perspective view of lamina 180. Lamina 180 has uniform thickness.

The at least one lamina 180 may have a thickness in the range from 25 pm to 200 pm. The at least one lamina 180 may have a thickness in the range from 100 pm to 150 pm. The at least one lamina 180 may have a thickness of 100 pm.

Although in Figures 3, 5A, 5B, 5C and 6 lamina 180 has uniform thickness, lamina 180 may have varying thickness.

Figure 7B illustrates lamina 180. Lamina 180 of has a plurality of protrusions 182. The protrusions 182 are arranged in a repeating pattern. The protrusions 182 are ridges that extend along the length of lamina 180.

Figure 7C is a perspective view of an alternative embodiment of lamina 180. Lamina 180 of Figure 7C has a plurality of protrusions 182. The protrusions 182 are arranged in a repeating pattern. Protrusions 182 are concave dimples (bumps) arranged in a grid formation.

Although protrusions 182 of Figures 7B and 7C are arranged on a single side of the lamina 180, the protrusions 182 may be arranged on a plurality of sides of the lamina 180. The protrusions 182 may also be located on a side of the lamina 180 that is to be adjacent the magnet block 160 in slot 140.

As an alternative, lamina 180 may have a single protrusion 182.

Although protrusions 182 of both Figures 7B and 7C are illustrated as ridges and bumps, respectively, protrusions 182 may take any protruding form.

Use of one or more protrusions 182 in the lamina 180 helps to retain the magnet block 160 within the slot 140 of the rotor core 120 by creating one or more points of increased friction between the magnet block 160 and the lamina 180, whilst also helping to consistently position the magnet block 160 in the slot 140 in order to reduce rotor unbalance.

Alternatively, or additionally, lamina 180 may have perforations.

Figure 7D is a perspective view of lamina 180. Lamina 180 of Figure 7D has a plurality of perforations 184. Perforations 184 are arranged in a repeating pattern. Perforations 184 are arranged across the width of lamina 180 in two parallel lines.

Perforations of lamina 180 are not limited to the perforations 184 of Figure 7D. Indeed, perforations of lamina 180 may be arranged in a different formation. Lamina 180 may have a greater or fewer number of perforations. For instance, lamina 180 may have a single perforation 184.

Use of one or more perforations 184 in the lamina 180 helps to retain the magnet block 160 within the slot 140 of the rotor core 120 whilst also helping to consistently position the magnet block 160 in the slot 140 in order to reduce rotor unbalance.

Figure 8 is a perspective view of lamina 180. Lamina 180 of Figure 8 has the shape of a wave form. Lamina 180 has an undulating cross section of lamina 180.

The undulations of lamina 180 help to retain the magnet block 160 within the slot 140 of the rotor core 120 by creating one or more points of increased pressure between the magnet block 160 and the lamina 180, whilst also helping to consistently position the magnet block 160 in the slot 140 in order to reduce rotor unbalance.

A vehicle 500 is shown in Figure 9. The vehicle 500 has a rotor core assembly 100. The rotor core assembly 100 may be part of an electric machine that acts as the traction engine of the vehicle 500. However, the location of the rotor core assembly 10 is not limited to being part of the traction engine of the vehicle 500. Rather, rotor core assembly 100 may form a part of other drive units within vehicle 500.

An electric machine comprising a rotor core assembly of an embodiment of the invention may form part of one or more of the following: an in-wheel drive unit, a wheel axle drive unit, a traction engine of a hybrid-electric vehicle, a traction engine of an electric vehicle, and a DC brushless motor.

The term magnet block used in this application means a block of magnetic material in the magnetised or un-magnetised condition. The magnet block may be provided with a surface coating which extends wholly or partially over the surface of the magnet block. Alternatively, the magnet block may be uncoated. Where the magnet block is partially coated, the uncoated portion of the magnet block may comprise the portion of the magnet block which contacts the lamina.

The term rotor core used in the application means a rotating part of an electric machine, which may typically be a laminated or solid construction that is manufactured from metal, for 19 example, copper, steel, aluminium or a combination of these materials. The term electric machine used in this application means an electric motor or generator.

Whilst the magnet block is illustrated as a single entity, the magnet block could be formed from a plurality of magnet blocks. In addition, a plurality of magnet blocks could be positioned in a single slot. For example, at least one lamina could be positioned in between and separating a plurality of blocks within a slot of a rotor core such that each of the plurality of blocks maintains a consistent position in the slot. As a modification, more than one lamina may be positioned in a single slot.

Whilst the magnet block has been shown as a cuboid, the magnet block could be any threedimensional shape.

Slots of a rotor core may, when viewed in plan view (from above), be arranged in pairs with matching or opposing magnetic poles. In addition, slots may be arranged substantially parallel to one another, substantially aligned with one another, or offset from one another. A slot may be formed by a number of laminations of the rotor core. A slot may be blind or open-ended.

The term lamina used in this application means a non-liquid layer of material. The lamina may be a solid layer of material. The lamina may be a thin-film of material having a thickness ranging from twenty five micrometres to several hundred micrometres.

The lamina may be moulded to each lamination forming the slot. The lamina may be deformed to mould to the shape of each lamination forming the slot. The lamina may be moulded to a single lamination forming the slot. The lamina may be deformed to mould to the shape of a single lamination forming the slot. The lamina may be moulded to a plurality of laminations forming the slot. The lamina may be deformed to mould to the shape of a plurality of laminations forming the slot.

The perforations and protrusions of the lamina can be arranged based on design, cost and assembly considerations and may have a different form than those illustrated and described in the detailed description.

Whilst the application of a lamina to either a magnet block or slot prior to insertion of the magnet block into a slot is described as an alternative to arranging a lamina between a magnet block and a slot prior to insertion of the magnet block into a slot, if more than one lamina is used in a single slot the applying and arranging may occur within the same assembly process.

Optionally, inserting of a lamina into a slot may occur after a magnet block has been inserted into the slot.

The curing of the lamina after inserting the lamina into a slot of the rotor core and the curing of the rotor core assembly may comprise spinning the rotor core assembly at the same time as applying heat to the rotor core assembly. For example, the rotor core assembly may be spun when heated in a curing oven or may be spun when heated using induction heating.

Optionally, liquid adhesive may be used in conjunction with a lamina in a slot of a rotor core to position a magnet block in the slot. For example, a lamina is used to position a magnet block in a slot of a rotor core and a liquid adhesive is used to fill in any gaps between at least one of the lamina and the magnet block and the lamina and the slot of the rotor core. The lamina is inserted into a slot of a rotor core and then a liquid adhesive is applied to one or more of the following: the lamina, the slot, and the magnet block. As an alternative, the liquid adhesive is first applied to one or more of the lamina, the slot, and the magnet block, and then the lamina is inserted into the slot. As such, the use of liquid adhesive can be an additional feature to the method 400, described earlier. In another variation, a majority of magnet blocks of a rotor core may be secured in corresponding slots by use of corresponding laminas, with the remaining magnet blocks of the rotor core secured in corresponding slots by a liquid adhesive.

For the above-described techniques, the lamina may be the primary instrument used to secure and position magnet blocks into slots of a rotor core so the amount of liquid adhesive required to secure and position the magnet blocks may be reduced.

Reducing the amount of liquid adhesive results in the following advantages: a consistent position of the magnet block within the slot can be achieved and rotor unbalance reduced; adhesive bleed-out between components of the electric machine and out from the end of the slot is reduced because less liquid adhesive is required and the lamina will not run onto, or spill onto, undesired surfaces of the magnet block or rotor core assembly when provided within a slot of the rotor core; further flexibility and certainty in relation to which surfaces of the magnet block the lamina is adjacent because the lamina, as the primary instrument for securing and positioning the magnet block, can be controlled and provided in a slot more reliably and easily than liquid adhesive; greater flexibility in the maintenance and cleaning processes used on the rotor core assembly because use of liquid adhesive, that can spill onto and bleed-out onto undesired surfaces of the rotor core assembly and interact with equipment of maintenance and cleaning processes, is reduced.

In an alternative embodiment of the present invention, the lamina may be substituted for a combination of liquid adhesive and solid particles. The solid particles may, for example, comprise glass particles or spheres commonly termed ballotini. The liquid adhesive and solid particle combination may, as with the previously described lamina embodiment, be applied to at least one side of the magnet block, or at least one surface of the slot. After insertion of the magnet block to the slot, the rotor core is rotated and heated in order to connect the magnet block to one or more surfaces of the slot.

Claims

1. A rotor core assembly for an electric machine, the rotor core assembly having an axis of rotation comprising:

2. The rotor core assembly of claim 1, wherein the at least one lamina is positioned adjacent a single face of the magnet block.

3. The rotor core assembly of claim 1, wherein the at least one lamina is positioned adjacent one of the following: two faces of the magnet block; three faces of the magnet block; four faces of the magnet block; and five faces of the magnet block.

4. The rotor core assembly of claim 3, wherein the at least one lamina is a continuous lamina so as to wrap around a plurality of faces of the magnet block.

5. The rotor core assembly of claim 4, wherein:

the rotor core comprises an upper surface;

the plurality of faces of the magnet block comprises a deepest face, wherein the deepest face is positioned furthest from the upper surface compared to the other faces of the plurality of faces; and the at least one lamina is adjacent the deepest face.

6. The rotor core assembly of any preceding claim, wherein the magnet block is a cuboid.

I. The rotor core assembly of any preceding claim, wherein the slot has a shape corresponding to the shape of the magnet block.

8. The rotor core assembly of any preceding claim, wherein at least a portion of the at least one lamina is moulded to the rotor core to aid retention of the magnet block in the slot.

9. The rotor core assembly of any preceding claim, wherein the at least one lamina comprises one of the following: an adhesive, a polymer, an adhesive composite, a polymer composite, and a combination of an adhesive and a polymer.

10. The rotor core assembly of any of claims 3 to 9, wherein the at least one lamina comprises fold lines to aid in folding of the at least one lamina around the magnet block.

II. The rotor core assembly of any preceding claim, wherein the at least one lamina has a thickness in the range from 25 pm to 200 pm.

12. The rotor core assembly of claim 11, wherein the at least one lamina has a thickness in the range from 100 pm to 150 pm.

13. The rotor core assembly of claim 12, wherein the at least one lamina has a thickness of 100 pm.

14. The rotor core assembly of any preceding claim, wherein the at least one lamina comprises a perforation.

15. The rotor core assembly of claim 14, wherein the at least one lamina comprises a plurality of perforations arranged in a repeating pattern.

16. The rotor core assembly of any preceding claim, wherein the at least one lamina comprises a protrusion on one side of the lamina.

17. The rotor core assembly of claim 16, wherein the protrusion is located on a side of the at least one lamina adjacent the magnet block.

18. The rotor core assembly of any of claims 16 or 17, wherein the at least one lamina comprises a plurality of protrusions arranged in a repeating pattern.

19. The rotor core assembly of any of claims 1 to 15, wherein the at least one lamina is uniform in thickness.

20. The rotor core assembly of any preceding claim, wherein the rotor core assembly is part of an electric machine.

21. A vehicle comprising the rotor core assembly of any preceding claim.

22. A method of assembling a rotor core assembly of an electric machine, the method comprising:

inserting a lamina within a slot of a rotor core;

inserting a magnet block into the slot of the rotor core; such that the lamina is arranged to position the magnet block within the slot; and rotating the rotor core to about an axis of rotation to urge the magnet and lamina into contact with a radially distal surface of the slot.

23. The method of claim 22, further comprising applying the lamina to one of the magnet block or the slot prior to inserting of the magnet block into the slot.

24. The method of claim 23, wherein the method comprises arranging the lamina between the magnet block and the rotor core prior to inserting the lamina, such that upon insertion of the magnet block into the slot, the lamina wraps around two or more faces of the magnet block to provide a consistent magnet block position in the slot.

25. The method of claim 24, wherein the method further comprises pre-folding the lamina prior to inserting the lamina in order to aid in wrapping of the lamina around two or more faces of the magnet block upon insertion of the magnet block into the slot.

Intellectual

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