WO2021074565A1

WO2021074565A1 - A stator assembly

Info

Publication number: WO2021074565A1
Application number: PCT/GB2020/052180
Authority: WO
Inventors: Daniel Stoner; Yu Chen
Original assignee: Dyson Technology Limited
Priority date: 2019-10-18
Filing date: 2020-09-10
Publication date: 2021-04-22
Also published as: GB201915074D0; GB2588585A

Abstract

A stator assembly (10) has a stator body (12), a plurality of slots (14) formed in the stator body (12), a phase winding (A,B,C) disposed in the plurality of slots (14), a connector holder (16), and a plurality of connectors (18). The phase winding (A,B,C) has a plurality of winding connection portions. The connector holder (16) has a main body (124), a base (122), and a wall (126) extending between the main body (124) and the base (122). The base (122) is in contact with an end face (128) of the stator body (12). The main body (124) has a plurality of holding members (144) that hold the plurality of connectors (18), and the plurality of connectors (18) are engaged with the plurality of winding connection portions of the phase winding (A,B,C).

Description

A Stator Assembly

FIELD OF THE INVENTION

The present invention relates to a stator assembly of an electric motor, an electric motor comprising a stator assembly, an electric vehicle comprising an electric motor, and a connector holder for holding connectors of a stator assembly of an electric motor.

BACKGROUND OF THE INVENTION

Stator assemblies in electric motors are typically provided with phase windings through which phase current is driven in use to create alternating magnetic fields. Connecting phase windings together in electric motors can prove complex and time consuming, which may add to the cost of manufacture of the motor.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a stator assembly comprising a stator body, a plurality of slots formed in the stator body, a phase winding disposed in the plurality of slots, a connector holder, and a plurality of connectors, wherein the phase winding comprises a plurality of winding connection portions, the connector holder comprises a main body, a base, and a wall extending between the main body and the base, the base is in contact with an end face of the stator body, the main body comprises a plurality of holding members that hold the plurality of connectors, and the plurality of connectors are engaged with the plurality of winding connection portions of the phase winding. The stator assembly according to the first aspect of the present invention may be advantageous principally as the connector holder comprises a main body, a base, and a wall extending between the main body and the base, the base is in contact with an end face of the stator body, the main body comprises a plurality of holding members that hold the plurality of connectors, and the plurality of connectors are engaged with the plurality of winding connection portions of the phase winding.

In particular, as the base is in contact with an end face of the stator, the base may ensure that the connector holder is stably located relative to the stator main body, whilst also ensuring that the main body, and hence the connectors held by the holding members, is held at the correct location for proper engagement of the connectors with the winding connection portions of the phase winding.

The main body may extend in a radial and circumferential direction of the stator body. The main body may have a radial extent corresponding substantially to the radial extent of the stator body from a radially outermost edge of the plurality of slots to a radially innermost edge of the plurality of slots. The main body may have a radial extent substantially corresponding to a radial extent of at least a portion of the phase winding, for example the entirety of the radial extent of the phase winding disposed in a slot. This may be beneficial as it may enable connectors to be held across the radial extent of the phase winding, and may enable connections to be made at either radial end of the phase winding.

The plurality of connectors, for example main portions or connector portions of the plurality of connectors, may be held at a plurality of radial positions along the main body. The plurality of holding members may be located at a plurality of radial positions along the main body. For example, the main body may comprise a plurality of discrete radial positions, and the plurality of holding members may be located at the plurality of discrete radial positions. Each of the plurality of slots may comprise a plurality of radial slot positions. The plurality of winding connection portions may be disposed in radial rows about the stator body. Each radial row may comprise a plurality of radial row positions. The plurality of radial positions may correspond to the plurality of radial slot positions and/or correspond to the plurality of radial row positions. This may be beneficial as it may enable connectors to be held by the connector holder at radial positions corresponding to radial positions of winding connection portions of the phase winding.

Each of the plurality of slots may comprise a plurality of radial slot positions. The plurality of winding connection portions may be disposed in a plurality of rows spaced about the stator body, each of the plurality of rows comprising a plurality of radial row positions.

The plurality of connectors may be held at substantially the same axial height, for example in a single axial layer. Main portions and/or connector portions of the plurality of connectors may be held at substantially the same axial height. The plurality of holding members may be located at substantially the same axial height. The main body may comprise a single-layered structure. This may provide a simpler and more compact arrangement than a multi-layer structure.

At least one of the connectors may comprise a main portion held by at least one holding member at a first radial position and at least one connection portion held by the at least one holding member at a second radial position. This may provide flexibility in location of connectors about the main body of the connector holder whilst still allowing connections to be made at desired radial positions. This may also result in a reduced axial height of the stator assembly compared to an arrangement where multiple connectors, for example main portions, are required to be located at the same radial position. At least one of the plurality of holding members may be shaped to hold a main portion of at least one of the connectors at a first radial position whilst allowing at least one connection portion of the same connector to extend to a second radial position. The main body may comprise N radial positions extending from a radially outermost radial position to a radially innermost radial position, for example extending from a first radially outermost radial position to an Nth radially innermost radial position. N may comprise an even integer, for example an even integer greater than or equal to 4.

A first connector, for example a connection portion of the first connector, may be held at the radially outermost position and a second connector, for example a connection portion of the second connector, may be held at the radially innermost position. The plurality of holding members may hold connection portions of connectors at the radially innermost radial position and at the radial outermost radial position. This may be beneficial as the connector holder may facilitate connections being made with the phase winding at spaced radial locations of the stator, thereby allowing for more room to make the connections, which may simplify the manufacturing process, saving cost and time.

The first connector, for example the connection portion of the first connector, at the radially outermost position may be held in alignment with the second connector, for example the connection portion of the second connector, at the radially innermost position. The plurality of holding members may hold connection portions of connectors such that connection portions at the radially innermost radial position are substantially aligned in a radial direction with connection portions at the radially outermost radial position. This may be beneficial as this may confine connection portions of connectors held by the connector body to a limited circumferential extent, thereby allowing the connector holder to only extend circumferentially about a portion of the stator body which the connector holder contacts in use, if desirable. A plurality of connection portions held at the radially innermost position may be held in circumferential alignment with a plurality of connection portions held at the radially outermost position.

Main portions of the first and second connectors may be held at radial positions intermediate the radially outermost and radially innermost radial positions, and the connection portions of the first and second connectors may be held at the respective radially outermost or radially innermost radial positions. The plurality of holding members may hold main portions of connectors at radial positions intermediate the radially innermost and radially outermost radial positions. For example, the plurality of holding members may hold a main portion of the first connector at the second radial position whilst the connection portion of the first connector is located at the first radial position, and/or the plurality of holding members may hold a main portion of the second connector at the (N-1 )th radial position whilst the connection portion of the second connector is located at the Nth radial position. This may be beneficial as it may enable the main bodies of connectors to be disposed away from connection locations, thereby maximising the room available to make the connections. A main portion of the first connector may be held at the second radial position whilst the connection portion of the first connector is held at the first radial position, and/or a main portion of the second connector may be held at the (N-1 )th radial position whilst the connection portion of the second connector is held at the Nth radial position.

The first and/or second connectors may comprise a main portion and at least two connection portions. The first connector may comprise a main portion and at least two connection portions disposed at the same end of the main portion, or may comprise a main portion and at least one connection portion disposed at each end of the main portion. The second connector may comprise a main portion and at least one connection portion disposed at each end of the main portion. The second connector may comprise connection portions held at first and second circumferentially spaced locations at the Nth radial positon, and a third connector comprising a main portion at the Nth radial position may comprise connection portions held at third and fourth circumferentially spaced locations at the Nth radial position, with the third and fourth circumferentially spaced locations being located adjacent to, and circumferentially inwardly of, the first and second circumferentially spaced locations. The main body may comprise a first holding member that holds a main portion of the second connector at the (N-1 )th radial position with connection portions of the second connector held at first and second circumferentially spaced locations at the Nth radial positon, and the main body may comprise a second holding member that holds a main portion of the third connector at the Nth radial position with connection portions of the third connector held at third and fourth circumferentially spaced locations at the Nth radial positions, with the third and fourth circumferentially spaced locations being located adjacent to, and circumferentially inwardly of, the first and second circumferentially spaced locations. This may enable a nested arrangement of connectors which may enable connections to be made at adjacent locations at the Nth radial position. This may be particularly beneficial where, for example, the stator requires connections between adjacent slots.

The plurality of connectors may comprise a plurality of connectors having the same structure as the first connector, a plurality of connectors having the same structure as the second connector, and a plurality of connectors having the same structure as the third connector. For example, the stator assembly may comprise a plurality of phase windings, and the stator assembly may comprise at least one first, second and third connector per phase winding.

The stator assembly may comprise a plurality of second and third connectors spaced about the main body, for example in a repeating pattern. The connector holder may comprise a circumferential extent corresponding substantially to a circumferential extent of a connection region of the stator body, for example a region of the stator body in which the winding connection portions of the phase winding are located. This may be beneficial as this may confine connection portions of connectors held by the connector holder to a limited circumferential extent, thereby allowing the connector holder to only extend circumferentially about a portion of the stator body. This may allow for a connector holder of reduced size, reduced mass, and reduced cost, relative to a connector holder having a circumferential extent corresponding to the full circumference of the stator body.

Alternatively, the connector holder may comprise a circumferential extent corresponding substantially to a full circumference of the stator body. For example, the base of the connector holder may comprise a circumferential extent corresponding substantially to a full circumference of the stator body. This may be beneficial as it may provide increased contact surface area between the connector holder and the stator, thereby resulting in a more stable arrangement. The base of the connector holder may comprise a circumferential extent corresponding substantially to a full circumference of the stator body and the main body of the connector holder may comprise a circumferential extent corresponding substantially to a circumferential extent of a connection region of the stator body. This may be beneficial as the base may provide support about the full circumference of the stator body whilst the main body holds connectors only in the connection region of the main body. This may allow for a connector holder of reduced mass and cost relative to an arrangement where the main body extends about the full circumference of the stator body.

The wall may extend orthogonally to the base. The base may contact an end face of the stator body such that the wall extends orthogonally relative to the end face of the stator body. The main body may extend orthogonally to the wall, for example such that the main body extends parallel to an end face of the stator body. The main body may extend at least partially over the phase winding. For example, the main body may extend over substantially the radial extent of a section of the phase winding. This may be beneficial as it may enable connections to be made at either radial end of a section of the phase winding.

The connector holder may comprise an electrically insulating material.

The plurality of connectors, for example at least main portions of the plurality of connectors, may be held on an upper surface of the main body, for example a surface of the main body that faces away from the stator body. The plurality of holding members may be disposed on an upper surface of the main body, for example a surface of the main body that faces away from the stator body. This may be beneficial as it may enable the main body of the connector holder to be disposed between main portion portions and the stator body, and may provide an insulating barrier between main portions and the stator main body, for example between the main portions and the phase winding.

The plurality of holding members may allow movement of connectors in at least one plane. For example, the plurality of holding members may allow movement of connectors in a plane parallel to an end face of the stator body. This may be beneficial as it may allow movement of connectors pre-connection to the winding connection portions of the phase winding, and this may facilitate the connection process.

At least one of the plurality of holding members may comprise a projection and/or recess that engages a corresponding recess and/or projection of a connector, for example that engages a corresponding recess and/or projection on a main portion. The projection or recess may define a channel for receiving at least a portion of a connector. The projection and/or recess may comprise a discrete projection and/or recess, for example a projection and/or recess with insufficient circumferential or radial extent to be considered a channel.

At least one of the plurality of holding members may comprise a channel that receives a corresponding connector, for example a main portion of a corresponding connector. The channel may comprise a substantially arcuate form, for example following the curvature of the stator body. The channel may be located at a radial position of the main body, and may follow the radial position along the main body. Ends of the channel may enable passage of a connector held in the channel between radial positions of the main body. Use of a channel may be beneficial as the walls of the channel may constrain the path of a connector, thereby acting to hold the connector in place.

At least one of the plurality of holding members may comprise a locating feature, for example a locating feature disposed in the channel. The locating feature may comprise a locating projection that engages with a corresponding locating recess formed in a connector held by the holding member. The locating projection may comprise a clip.

The winding connection portions may comprise an input connection and/or an output connection and/or an intra-phase connection, for example of the same phase winding. The stator may comprise a plurality of phase windings. The winding connection portions for each phase winding may comprise an input connection and/or an output connection and/or an intra-phase connection. The plurality of connectors may comprise connectors for connecting to each phase winding.

At least one of the plurality of connectors may comprise an input connector, for example a connector configured to input phase current to a phase winding of a stator assembly in use. The stator assembly may comprise a plurality of input connectors, one for each phase winding of the stator assembly. The first connector may comprise an input connector.

The main body may comprise at least one holding member that holds an input connector for the phase winding. The main body may comprise a plurality of holding members each holding a respective input connector of a respective phase winding of the stator.

At least one of the plurality of connectors may comprise an intra-phase connector, for example a connector configured to connect two portions of the same phase winding of a stator assembly in use. This may be beneficial as it may enable more flexibility in the design of the phase winding, for example enabling a design where two discrete portions of a phase winding are located in different regions of the stator body yet connected by the intra-phase connector. The main body may comprise at least one holding member that holds an intra-phase connector for connecting portions of the same phase winding. The plurality of connectors may comprise a plurality of intra-phase connectors, and the main body may comprise a plurality of holding members each holding a respective intra-phase connector for connecting portions of the same phase winding. Where the stator comprises a plurality of phase windings, the plurality of connectors may comprise a plurality of intra-phase connectors, and the main body may comprise a plurality of holding members each holding a respective intra-phase connector for connecting portions of the respective same phase winding. The second and/or third connectors may comprise intra-phase connectors.

The base may comprise a radial extent corresponding substantially to a radial extent of a coreback of the stator body. For example, the base may comprise a radial extent corresponding substantially to a radial extent of the stator body between a perimeter of the stator body and a radially outermost boundary of the slots. This may be beneficial as it may maximise the contact surface area between the base and the stator body, without impacting on the phase winding.

The base may comprise a substantially arcuate form, for example following the curvature of the stator body. The base may be axially spaced from the main body by the wall, for example spaced in a direction orthogonal to an end face of the stator body. Thus the base and the main body may be located at two axial heights relative to the stator body. This may be beneficial as it may enable connections to be spaced from an end face of the stator body.

The base may comprise at least one foot in contact with the end face of the stator body.

The plurality of connectors may comprise at least one base connector held by the base. For example, the base may comprise at least one further holding member that holds at least one base connector. The base connector may be held at a different axial height relative to connectors held by the main body. For example, the at least one further holding member may hold a base connector at a different axial height relative to connectors held by the plurality of holding members of the main body. This may be beneficial as it may enable connections to be made at different axial heights, thereby maximising the space available for connections to be made and enabling ease of connection in use.

The base connector may be held at a base position that is radially outward from the plurality of radial positions of the main body. The at least one further holding member may be located at a base position that is radially outward from the plurality of radial positions of the main body. For example, the radial positions of the main body may correspond substantially to radial slot positions of the plurality of slots, whilst the radial position of the base, and hence the at least one further holding member and the at least one base connector, may correspond substantially to a radial position of a coreback of the stator body.

The at least one further holding member may hold a main portion of the base connector at a base radial position and at least one connection portion of the base connector may be held at a radial position corresponding to a first radial position of the main body. This may be beneficial as it may enable connectors to make connections at the same radial position, for example at a radial position corresponding to the first radial position of the main body.

At least one of the plurality of connectors may comprise an output connector, for example a connector configured to receive phase current from the phase winding. The plurality of connectors may comprise an output connector, for example a neutral connector, which connects to each phase winding of the stator assembly. The output connector may therefore be referred to as an inter-phase connector. The base connector may comprise an output, for example a neutral, connector, which connects to each phase winding of the stator assembly.

The at least one further holding member may hold an output connector, for example a neutral connector, whilst at least one holding member of the main body hold an input connection, for example a phase terminal. This may be beneficial as input and output connectors may be used to make connections at the same radial position.

The wall may comprise at least one window which allows the passage of connection portions of a connector, for example at least one window which allows the passage of connection portions of the base connector. This may be beneficial as it may facilitate formation of connections at different axial heights, for example enabling a connection at a different axial height relative to the axial height of connections formed by connectors held by the main body. This may also be beneficial as the window may remove material from the connector holder, thereby reducing mass and cost. The wall may comprise a plurality of windows, each window allowing the passage of connection portions of a connector, for example the base connector. Each window may allow for connection to a single phase winding of a stator in use.

The plurality of connectors may comprise electrical conductors, for example wire of bar sections formed of an electrically conductive material. At least some of the plurality of connectors may comprise electrical jumpers, for example electrical connectors used to connect two distal portions of an electrical circuit.

The stator body may be comprise a generally annular form, for example with a central aperture for receiving a rotor assembly therein.

The phase winding may comprise first and second parallel branches, each branch comprising an input winding connection portion, an output winding connection portion, and at least two intra-phase winding connection portions. Intra-phase winding connection portions of the first parallel branch may be located at first and second circumferentially spaced locations at the radially innermost position, and intra-phase winding connection portions of the second parallel branch may be located at third and fourth circumferentially spaced locations at the radially innermost position. The third and fourth circumferentially spaced locations may be located intermediate the first and second circumferentially spaced locations. A first intra-phase connector may extend between the first and second circumferentially spaced locations at a radial position radially outward of the radially innermost position, and a second intra-phase connector may extend between the third and fourth circumferentially spaced locations.

Input and output winding connection portions may be located at the radially outermost position. The phase winding may start and end at the radially outermost position. Intra-phase winding connection portions may be located at the radially innermost position. Intra — phase connections of the phase winding may be made at the radially innermost position.

According to a second aspect of the present invention there is provided an electric motor comprising a stator according to the third aspect of the present invention.

According to a third aspect of the present invention there is provided an electric vehicle comprising an electric motor according to the fourth aspect of the present invention.

According to a fourth aspect of the present invention there is provided a connector holder for holding connectors of a stator assembly of an electric motor, the connector holder comprising a main body, a base, and a wall extending between the main body and the base, wherein the base is configured to contact an end face of a stator body of the stator assembly in use, and the main body comprises a plurality of holding members for holding a plurality of connectors.

Preferential features of aspects of the present invention may be equally applied to other aspects of the present invention, where appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present invention, and to show more clearly how the invention may be put into effect, the invention will now be described, by way of example, with reference to the following drawings:

Figure 1a is a schematic perspective view of a stator assembly according to the present invention; Figure 1b is a schematic exploded view of the stator assembly of Figure 1a;

Figure 2 is a schematic end view of a stator body for use in the stator assembly of Figure 1a;

Figure 3 is a schematic view of a hairpin winding for use in the stator assembly of Figure 1a;

Figure 4 is a schematic end view of the stator body of Figure 2 with phase windings inserted;

Figure 5 is a first schematic view illustrating radial positions of ends of hairpin windings in the wound stator body of Figure 4;

Figure 6 is a schematic illustration of the electric connections of the phase windings of the wound stator body of Figure 4;

Figure 7 is a second schematic view illustrating radial positions of ends of hairpin windings in the wound stator body of Figure 4;

Figure 8 is a schematic perspective view illustrating a first embodiment of a connector holder for use in the stator assembly of Figure 1 ;

Figure 9 is a schematic top plan view of the connector holder of Figure 8;

Figure 10 is a schematic perspective view of an output connector for use in the stator assembly of Figure 1 ;

Figure 11 is a schematic perspective view of a first intra-phase connector for use in the stator assembly of Figure 1 ; Figure 12 is a schematic perspective view of a second intra-phase connector for use in the stator assembly of Figure 1 ;

Figure 13 is a schematic perspective view of an input connector for use in the stator assembly of Figure 1 ;

Figure 14 is a schematic view illustrating the positioning of a plurality of connectors for use in the stator assembly of Figure 1 ;

Figure 15 is a schematic view illustrating the connectors of Figure 14 located in position in the connector holder of Figure 8;

Figure 16 is a schematic view illustrating an electric motor according to the invention;

Figure 17 is a schematic view illustrating an electric vehicle according to the invention; and

Figure 18 is a schematic perspective view illustrating a second embodiment of a connector holder for use in the stator assembly of Figure 1 .

DETAILED DESCRIPTION

A stator assembly according to the first aspect of the present invention, generally designated 10, is shown in Figures 1a and 1 b.

The stator assembly 10 comprises a stator body 12, a plurality of slots 14 formed in the stator body 12, first, second and third phase windings disposed in the plurality of slots 14, a connector holder 16, and a plurality of connectors 18. The first, second and third phase windings will be referred to as A, B, and C phase windings respectively, as is common in the art.

The stator body 12, as shown in Figures 1a, 1 b and 2, is generally cylindrical in form and has a central aperture for receiving a rotor assembly 202, as will be briefly described later. The stator body 12 is formed of electrical steel, as is typical for a stator body of an electric motor.

The plurality of slots 14 are generally rectangular in form, and each slot 14 has four radial slot positions 20,22,24,26, indicated schematically for a limited number of slots 14 in Figure 2, arranged from the first radial position 20 at a radially outer side of the stator body 12 to the fourth radial position 26 at a radially inner side of the stator body 12. In the present embodiment there are 60 slots.

The slots 14 are arranged in slot runs around the main body, with each slot run corresponding to a particular phase. The slot runs cycle circumferentially about the main body 12, such that a first slot run corresponds to phase A, a second slot run adjacent to the first slot run corresponds to phase B, a third slot run adjacent to the second slot run corresponds to phase C, a fourth slot run adjacent to the third slot run corresponds to phase A, and so on.

Each phase winding A,B,C has generally the same structure, and so only phase winding A will be described here for the sake of brevity.

Phase winding A is formed of a plurality of hairpin windings 28 electrically connected together. Each hairpin winding 28 has first 30 and second arms 32, with the first 30 and second 32 arms joined via a generally u- or v- shaped portion 34, as shown in Figure 3. Each hairpin winding 28 is inserted into the stator body 12 such that a first arm 30 of the hairpin winding 28 is located in a first slot 14, and a second arm 32 of the hairpin winding 28 is located in a second slot 14 spaced circumferentially around the stator body 12 from the first slot 14. In the embodiment shown, the slot pitch of the hairpin windings 28 is six, for example such that a hairpin winding 28 having a first arm 30 located in a nominal slot 14 labelled Ί” has a corresponding second arm 32 located in a nominal slot 14 labelled “7”.

The hairpin windings 28 are inserted into the stator 10 such that the hairpin windings 28 form outer 36 and inner 38 winding layers, as shown schematically in Figure 4. In the outer winding layer 36, hairpin windings 28 are located in slots 14 such that first arms 30 are located in first radial slot positions 20, and second arms 32 are located in second radial slot positions 22. In the inner winding layer 38, hairpin windings 28 are located in slots 14 such that first arms 30 are located in third radial slot positions 24, and second arms 32 are located in fourth radial slot positions 26. Thus the outer winding layer 36 occupies the first 20 and second 22 radial slot positions, and the inner winding layer 38 occupies the third 24 and fourth 26 radial slot positions.

When the hairpin windings 28 are located in slots 14, ends 40,42 of respective arms 30,32 extend axially outwardly from the stator body 12. To enable connection of the hairpin windings 28, the ends 40,42 are twisted/bent such that the ends 40,42 extend circumferentially about the stator body 12 relative to the corresponding arms 30,32, before being twisted such that the ends 40,42 extend in an axial direction perpendicular to the stator body 12. The ends 40 and ends 42 are twisted in opposing directions, ie with the ends 40 being twisted in a clockwise direction when viewed from a termination end of the stator body 12, and the ends 42 being twisted in an anti-clockwise direction when viewed from a termination end of the stator body 12.

The ends 40,42 of each hairpin winding 28 are twisted by the same degree. This gives an arrangement where ends 40,42 are aligned in radial rows 44, with each radial row 44 having four radial positions 46,48,50,52, as illustrated schematically in Figure 5. In the present embodiment, the degree of twisting is such that each radial row 44 overlies a corresponding slot 14, although it will be appreciated by a person skilled in the art that arrangements where radial rows 44 are misaligned with slots 14 are also envisaged.

The electrical connection of the hairpin windings 28 to form the phase winding A, given the positioning of the ends 40,42, is discussed below, with reference to Figures 5 to 7.

As can be seen from Figure 6, each phase winding A,B,C has first 54 and second 56 phase winding branches electrically connected in parallel. The first 54 and second 56 phase winding branches have a similar structure, with the first phase winding branch 54 comprising a first sequence 57 of four loops 58,60,62,64 electrically connected together in series, and the second phase winding branch 56 comprising a second sequence 59 of four loops 66,68,70,72 electrically connected together in series.

Each loop 58,60,62,64,66,68,70,72 is constructed from a number of hairpin windings 28, and comprises hairpin windings 28 which, when connected together, create a loop about the stator body 12. Flere a loop 58,60,62,64,66,68,70,72 is considered to be formed where an electrical path can be traced from an end 40 at a first radial position 46 of a given radial row 44 to an end 42 at a second radial position 48 of the same radial row 44, or vice versa, and where an electrical path can be traced from an end 40 at a third radial position 50 of a given radial row 44 to an end 42 at a fourth radial position 52 of the same radial row 44, or vice versa.

The first loops 58,66 of each parallel branch 54,56 utilise hairpin windings 28 of the outer winding layer 36. The second loops 60,68 of each parallel branch 54,56 utilise hairpin windings 28 of the inner winding layer 38. The third loops 62,70 of each parallel branch 54,56 utilise hairpin windings 28 of the inner winding layer 38. The fourth loops 64,72 of each parallel branch 54,56 utilise hairpin windings 28 of the outer winding layer 36.

From the discussion above, it will be appreciated that ends 40,42 of successive hairpin windings 28 within a loop 58,60,62,64,66,68,70,72 are located adjacent to one another within a given radial row 44. Thus connections within a loop 58,60,62,64,66,68,70,72 are so-called direct connections, formed by welding ends 40,42 together. These direct connections can be seen in Figures 5 and 7.

The nature of the loops 58,60,62,64,66,68,70,72 also means that adjacent loops 58,60,62,64,66,68,70,72 in the first 57 and second 59 sequences need to be connected together. The start and ends of loops 58,60,62,64,66,68,70,72 may be referred to as winding connection portions.

As can be seen from Figures 5 to 7, the first loop 58 of the first sequence 57 starts at the first radial position 46 of a first radial row 74, and ends at the second radial position 48 of the first radial row 74. The second loop 60 of the first sequence 57 starts at the third radial position 50 of the first radial row 74, and ends at the fourth radial position 52 of the first radial row 74. The third loop 62 of the first sequence 57 starts at the fourth radial position 52 of a second radial row 76, and ends at the third radial position 50 of the second radial row 76. The fourth loop 64 of the first sequence 57 starts at the second radial position 48 of the second radial row 76, and ends at the first radial position 46 of the second radial row 76. The first 74 and second 76 radial rows in this case are spaced apart with six radial rows 44 located therebetween.

It will be recognised that the winding connection portion 78 at the end of the first loop 58 is located adjacent the winding connection portion 80 at the start of the second loop 60 in the first radial row 74. Similarly, the winding connection portion 82 at the end of the third loop 62 is located adjacent the winding connection portion 84 at the start of the fourth loop 64 in the second radial row 76. These adjacent winding connection portions 78,80 and 82,84 are connected via a direct weld.

However, the winding connection portion 86 at the end of the second loop 60 is spaced apart circumferentially from the winding connection portion 88 at the start of the third loop 62 by virtue of the spacing between the first 74 and second 76 radial rows. Thus no direct connection can be made, and an indirect connection is required. This indirect connection is made by a first intra-phase connector 90, which will be described in more detail hereafter.

Similarly for the second phase winding branch 56, the first loop 66 of the second sequence 59 starts at the first radial position 46 of a third radial row 92, and ends at the second radial position 48 of the third radial row 92. The second loop 68 of the second sequence 59 starts at the third radial position 50 of the third radial row 92, and ends at the fourth radial position 52 of the third radial row 92. The third loop 70 of the second sequence 59 starts at the fourth radial position 52 of a fourth radial row 94, and ends at the third radial position 50 of the fourth radial row 94. The fourth loop 72 of the second sequence 59 starts at the second radial position 48 of the fourth radial row 94, and ends at the first radial position 46 of the fourth radial row 94. The third 92 and fourth 94 radial rows in this case are spaced apart with four radial rows 44 located therebetween. It will be recognised that the winding connection portion 96 at the end of the first loop 66 is located adjacent the winding connection portion 98 at the start of the second loop 68 in the third radial row 92. Similarly, the winding connection portion 100 at the end of the third loop 70 is located adjacent the winding connection portion 102 at the start of the fourth loop 72 in the fourth radial row 94. These adjacent winding connection portions 96,98 and 100,102 are connected via a direct weld.

However, the winding connection portion 104 at the end of the second loop 68 is spaced apart circumferentially from the winding connection portion 106 at the start of the third loop 70 by virtue of the spacing between the third 92 and fourth 94 radial rows. Thus no direct connection can be made, and an indirect connection is required. This indirect connection is made by a second intra-phase connector 108, which will be described in more detail hereafter.

It can also be seen from Figure 7 that the third radial row 92 is located adjacent to the first radial row 74, and the fourth radial row 94 is located adjacent to the second radial row 76, whilst the third 92 and fourth 94 radial rows are located between the first 74 and second 76 radial rows. This gives a nested arrangement for the radial rows, and requires special consideration for the form of the first 90 and second 108 intra-phase connectors, as will be discussed in more detail later.

As the third radial row 92 is located adjacent to the first radial row 74, a common input connector 110 is used to connect to the winding connection portion 112 at the start of the first loop 58 of the first phase winding branch 54 and the winding connection portion 114 at the start of the first loop 66 of the second phase winding branch 56. The form of the input connector 110 will be discussed in more detail later.

As the fourth radial row 94 is located adjacent to the second radial row 76, a common output connector 116 is used to connect to the winding connection portion 118 at the end of the fourth loop 64 of the first phase winding branch 54 and the winding connection portion 120 at the end of the fourth loop 72 of the second phase winding branch 56. The form of the common output connector 116 will be discussed in more detail later. As previously mentioned, each phase winding A,B,C has a similar structure, and hence it will be appreciated that similar input 110, output 116, and intra-phase 90,108 connectors are also used for connecting phase windings B and C. These connectors 90,108,110,116 form the plurality of connectors 18 of the stator assembly 10 previously referred to. As well as being welded to their respective winding connection portions, the plurality of connectors 18 are held in place by the connector holder 16.

The connector holder 16 is shown in isolation in Figures 8 and 9.

The connector holder 16 has a base 122, a main body 124, and a wall 126 extending between the base 122 and the main body 124.

The base 122 is generally arcuate in form, and follows the curvature of an end face 128 of the stator body 12. The base 122 has feet (not shown) which contact the end face 128 to locate the connector holder 16 relative to the remainder of the stator body 12. The feet contact the end face 128 at a position of a coreback 130 of the stator body 12, between the phase windings A,B,C and the perimeter of the stator body 12.

The base 122 has a base connector channel 132 that receives the output connector 116. The output connector 116 is shown in Figure 10, and has a main portion 134 and three connector portions 136 extending axially upwardly from the main portion 134, each connector portion 136 having two arms 138. As well as extending axially upwardly, the connector portions 136 extend radially inwardly from the position of the base to the first radial positions 46 of the radial rows 44. The connector portions 136 do not extend axially to the same extent as the wall 126, such that the connector portions 136 are located axially below the main body 124. This enables connections to be made at different axial heights, thereby providing more space for connections to be made, and allowing for easier and simpler formation of connections.

The wall has three windows 140, and each connector portion 136 extends through a respective window 140 to connect to respective winding connection portions at the ends of fourth loops 64,72 of respective phase winding branches. The windows 140 not only allow passage of the connector portions 136, but also remove material from the connector holder 16, thereby reducing the mass and cost of the connector holder 16.

As the output connector 116 connects to each phase winding A,B,C, the output connector 116 takes the form of a neutral connection in practice.

The main body 124 is generally planar and arcuate in form, and follows the curvature of both the base 122 and the end face 128 of the stator body 12. The main body 124 extends substantially orthogonally relative to the wall 126. The wall 126 is located at a radially inner side of the base 122, such that the main body 124 extends radially inwardly from the radially inner side of the base 122. The main body 124 extends radially from an outer edge of the plurality of slots 14 to an inner edge of the plurality of slots 14, such that the main body 124 covers the phase windings A,B,C disposed in the slots 14 in the region of winding connection portions of the phase windings A,B,C. The connector holder 16 is formed of electrically insulating material, such that the main body 124 forms an electrically isolating barrier between the phase windings A,B,C and the plurality of connectors 18 other than in regions where electrical connections are desired.

The main body 124 has a plurality of holding members in the form of projections 142 on the upper surface of the main body 124 that define channels 144 about the main body 124. In particular, the projections 142 are located about the main body 124 so as to define channels 144 at a plurality of discrete radial positions 146,148,150,152 along the main body 124. In the present embodiment the plurality of radial positions 146,148,150,152 of the main body 124 correspond substantially to both the plurality of radial slot positions 20,22,24,26 of the plurality of slots 14, and the plurality of radial positions 46,48,50,52 of the plurality of radial rows 44. In particular, the plurality of radial positions 146,148,150,152 of the main body 124 are substantially radially aligned with the plurality of radial slot positions 20,22,24,26 of the plurality of slots 14, and the plurality of radial positions 46,48,50,52 of the plurality of radial rows 44.

Each of the channels 144 is shaped according to the connector 18 it is intended to hold. Some channels 144 have a locating projection 145 which engages a corresponding locating aperture 147 on a respective one of the plurality of connectors 18 to locate the connector within the channel 144. The engagement of the locating projections 145 and the locating apertures 147 is such that limit movement, eg twisting, of the connectors 18 in a plane parallel to the end face 128 of the stator body 12 is enabled. This may provide some flexibility in forming connections between the plurality of connectors 18 and the winding connection portions.

The first intra-phase connector 90, as shown in Figure 11 , has a main portion 154, and a connector portion 156 disposed at each end of the main portion 154. The connector portions 156 extend in a direction substantially orthogonal to that of the main portion 154 in the same plane as the main portion 154, as well as extending slightly axially relative to the main portion 154. Hence the channel 144 that receives the first intra-phase connector 90 has walls that support the main portion 154, but enable the passage of the connector portions 156. The channel 144 that receives the main portion 154 of the first intra-phase connector 90 is located at the third radial position 150 of the main body 124, whilst the connector portions 156 are allowed to extend to the fourth radial position 152. The second intra-phase connector 108, as shown in Figure 12, has a main portion 158 and a connector portion 160 disposed at each end of the main portion 158. The connector portions 160 extend slightly axially relative to the main portion 158. The channel 144 that receives the second intra-phase connector 108 has walls that support the main portion 158. The channel 144 that receives the main portion 158 second intra-phase connector 108 is located at the fourth radial position 152 of the main body 124, and the connector portions 160 of the second intra-phase connector 108 are also located at the fourth radial position 152 of the main body 124.

The main portion 158 of the second intra-phase connector 108 is shorter than the main portion 154 of the first intra-phase connector 90. This enables the connector portions 160 of the second intra-phase connector 108 to be located between the connector portions 156 of the first intra-phase connector 90 in a nested arrangement.

The intra-phase connectors 90,108 have the same form for each phase winding A,B,C, and hence the pattern of channels 144 for holding intra-phase connectors 90,108 is generally repeated along the circumferential extent of the main body 124.

As can be seen, the connector portions 156,160 of each intra-phase connector 90,108 are located at the fourth radial position 152 of the main body 124. This enables all intra-phase connections to be formed at a common radial position, thereby simplifying manufacture and saving cost.

The input connector 110 of phase winding A, as can be seen in Figure 13, has a main portion 162, two connector portions 164 extending from a first end of the main portion 162, and a terminal connection 166 extending from a second opposite end of the main portion 162. The connector portions 164 extend in a direction substantially orthogonal to that of the main portion 162 in the same plane as the main portion 162, as well as extending slightly axially relative to the main portion 162. The terminal connection 166 extends in an axial direction from the main portion 162, and connects to a current supply in use. The channel 144 that receives the input connector 110 has walls that support the main portion 162, but which do not support the connector portions 164. The channel 144 that receives the main portion 162 of the input connector 110 is located at the second radial position 148 of the main body 124, whilst the connector portions 164 are allowed to extend to the first radial position 146.

The input connectors 110 are the same for phase windings A and C, and although the form of the input connector for phase winding B is slightly different (as seen in Figure 14), the main portion and connector portions of the input connector 110 of phase winding B are held at the same radial positions as those of the input connectors 110 of phase windings A and C.

As previously mentioned, connector portions 136 of the output connector 116 extend to the first radial position 46 of the radial rows, and hence connector portions 136 of the output connector 116 are also located at the first radial position 146 of the main body 124. This enables both input and output connections of the phase windings A,B,C to be made at the same radial position, thereby simplifying manufacture and saving cost.

The channels 144, base connector channel 132, and the plurality of connectors 18 are chosen and shaped so that connector portions 156,160 at one end of the respective intra-phase connectors 90,108 for a given phase winding are substantially circumferentially aligned with connector portions 164 of the input connector 110 for that phase winding, and connector portions 156,160 at the other end of the respective intra-phase connectors 90,108 for the phase winding are substantially circumferentially aligned with connector portions 136 of the output connector 116. This therefore corresponds with the location of winding connection portions of the phase winding as previously discussed, and enables easy connection of the plurality of connectors 18 to the phase windings A,B,C.

The plurality of connectors 18 can be seen in isolation in Figure 14, and located in the connector holder 16 in Figure 15.

During manufacture of the stator assembly, the connector holder 16 and the plurality of connectors 18 may be provided as a pre-assembled unit. Such a unit can then be lowered onto a wound stator body 12, and the plurality of connectors can be clamped and welded to the corresponding winding connection portions of the phase windings A,B,C. Use of such a pre-assembled unit may simplify manufacture by removing steps, thereby saving time and cost.

An electric motor 200 comprising the stator assembly 10 is shown schematically in Figure 16. Details of the electric motor 200 are not pertinent to the present invention, and so the electric motor 200 will not be described here for the sake of brevity save to say that the electric motor 200 has a rotor assembly 202 that rotates when current is passed through the stator assembly 10 in use.

An electric vehicle 300 comprising the electric motor 200 is shown schematically in Figure 17. Details of the electric vehicle 300 are not pertinent to the present invention, and so will not be described here for the sake of brevity.

A second embodiment of a connector holder for use in the stator assembly 10 is shown in Figure 18, and generally designated 400.

The connector holder 400 has largely the same structure as the connector holder 16 previously described, save that instead of locating projections 145, the connector holder 400 comprises a plurality of clips 402 located in channels 144. The clips 402 act to retain the plurality of connectors 18 in the channels 144. The plurality of connectors 18 are still held such that respective connector portions at the same location as those described previously in conjunction with the first embodiment of the connector holder 16.

Claims

1. A stator assembly comprising a stator body, a plurality of slots formed in the stator body, a phase winding disposed in the plurality of slots, a connector holder, and a plurality of connectors, wherein the phase winding comprises a plurality of winding connection portions, the connector holder comprises a main body, a base, and a wall extending between the main body and the base, the base is in contact with an end face of the stator body, the main body comprises a plurality of holding members that hold the plurality of connectors at a plurality of radial positions along the main body, and the plurality of connectors are engaged with the plurality of winding connection portions of the phase winding, wherein the main body comprises N radial positions extending from a radially outermost radial position to a radially innermost radial position, where N comprises an even integer greater than or equal to 4, and a connection portion of a first connector is held at the radially outermost position and a connection portion of a second connector is held at the radially innermost position.

2. A stator assembly as claimed in Claim 1 , wherein the main body extends in a radial and circumferential direction of the stator body, and the main body has a radial extent corresponding substantially to a radial extent of at least a portion of the phase winding.

3. A stator assembly as claimed in Claim 1 or Claim 2, wherein each of the plurality of slots comprises a plurality of radial slot positions, the plurality of winding connection portions are disposed in radial rows about the stator body, each radial row comprising a plurality of radial row positions, the plurality of radial positions correspond to the plurality of radial slot positions and/or correspond to the plurality of radial row positions.

4. A stator assembly as claimed in any preceding claim, wherein at least one of the connectors comprises a main portion held by at least one holding member at a first radial position and at least one connection portion held by the at least one holding member at a second radial position.

5. A stator assembly as claimed in any preceding claim, wherein the connection portion at the radially outermost position is held in alignment with the connection portion at the radially innermost position.

6. A stator assembly as claimed in any preceding claim, wherein main portions of the first and second connectors are held at radial positions intermediate the radially outermost and radially innermost radial positions, and the connection portions of the first and second connectors are held at the respective radially outermost or radially innermost radial positions.

7. A stator assembly as claimed in Claim 6, wherein a main portion of the first connector is held at the second radial position whilst the connection portion of the first connector is held at the first radial position, and a main portion of the second connector is held at the (N-1 )th radial position whilst the connection portion of the second connector is held at the Nth radial position.

8. A stator assembly as claimed in Claim 7, wherein the second connector comprises connection portions held at first and second circumferentially spaced locations at the Nth radial positon, and a third connector comprising a main portion held at the Nth radial position comprises connection portions held at third and fourth circumferentially spaced locations at the Nth radial positions, with the third and fourth circumferentially spaced locations being located adjacent to, and circumferentially inwardly of, the first and second circumferentially spaced locations.

9. A stator assembly as claimed in any preceding claim, wherein the connector holder comprises a circumferential extent corresponding substantially to a circumferential extent of a connection region of the stator body in which the winding connection portions of the phase winding are located.

10. A stator assembly as claimed in any of Claims 1 to 8, wherein the connector holder comprises a circumferential extent corresponding substantially to a full circumference of the stator body.

11. A stator assembly as claimed in any preceding claim, wherein the wall extends orthogonally to the base, and the main body extends orthogonally to the wall.

12. A stator assembly as claimed in any preceding claim, wherein the connector holder comprises an electrically insulating material.

13. A stator assembly as claimed in any preceding claim, wherein the plurality of connectors are held on an upper surface of the main body, and the plurality of holding members are disposed on an upper surface of the main body.

14. A stator assembly as claimed in any preceding claim, wherein the plurality of holding members allow movement of connectors in at least one plane.

15. A stator assembly as claimed in any preceding claim, wherein at least one of the plurality of holding members comprises a projection and/or recess that engages a corresponding recess and/or projection of a connector.

16. A stator assembly as claimed in any preceding claim, wherein at least one of the plurality of holding members comprises a channel that receives a corresponding connector.

17. A stator assembly as claimed in any preceding claim, wherein at least one of the plurality of connectors comprises an input connector.

18. A stator assembly as claimed in any preceding claim, wherein at least one of the plurality of connectors comprises an intra-phase connector.

19. A stator assembly as claimed in Claim 18, wherein the phase winding comprises first and second parallel branches, the plurality of winding connection portions comprise intra-phase winding connection portions, intra-phase winding connection portions of the first parallel branch are located at first and second circumferentially spaced locations at a radially innermost position of the main body, and intra-phase winding connection portions of the second parallel branch are located at third and fourth circumferentially spaced locations at the radially innermost position, the third and fourth circumferentially spaced locations are located intermediate the first and second circumferentially spaced locations, a first intra-phase connector extends between the first and second circumferentially spaced locations at a radial position radially outward of the radially innermost position, and a second intra-phase connector extends between the third and fourth circumferentially spaced locations at the radially innermost position.

20. A stator assembly as claimed in any preceding claim, wherein the base comprises a radial extent corresponding substantially to a radial extent of a coreback of the stator body.

21. A stator assembly as claimed in any preceding claim, wherein the base comprises at least one further holding member that holds at least one base connector.

22. A stator assembly as claimed in Claim 21 , wherein the base connector is held at a different axial height relative to connectors held by the main body.

23. A stator assembly as claimed in Claim 21 or Claim 22, wherein the base connector is held at a base position that is radially outward from the plurality of radial positions of the main body, a main portion of the base connector is held at the base radial position, and at least one connection portion of the base connector is held at a radial position corresponding to a first radial position of the main body.

24. A stator assembly as claimed in any preceding claim wherein the wall comprises at least one window which allows the passage of connection portions of a connector

25. An electric motor comprising a stator assembly as claimed in any preceding claim.

26. An electric vehicle comprising an electric motor as claimed in Claim 25.