Vehicle electric drive unit component

Abstract

A vehicle electric drive unit component 30A comprises a bayonet connector 52 for engaging a bayonet receiver 54 of a different vehicle electric drive unit component 12. The connector 52 comprises: a

Description

TECHNICAL FIELD The present disclosure relates to a vehicle electric drive unit component. Aspects of the invention relate to an assembly, to an electric machine and to a vehicle. BACKGROUND It is known to connect two vehicle electric drive unit components together. Such components may be subjected to high temperature and / or high pressures, and thus are required to have a robust connection therebetween. For example, there may be provided an electrical machine with a stator core having a plurality of cooling passageways which extend in a longitudinal direction through the stator core. In such an electrical machine, there maybe a cooling fluid manifold which defines a chamber in fluid communication with the cooling passageways. In this way, a flow of cooling fluid can be input to the chamber and then through the cooling passageways to remove heat from the stator core. The cooling fluid manifold may be subject to high temperatures and / or pressures, and so a robust connection between the manifold and the stator core is required to prevent leaks and loss of cooling fluid. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a stator assembly, a cooling manifold, a stator core, an electric machine, and a vehicle as claimed in the appended claims. According to an aspect of the present disclosure, there is provided a vehicle electric drive unit component comprising at least one bayonet connector for engaging a bayonet receiver of a different vehicle electric drive unit component, wherein the at least one bayonet connector comprises: a first projection having a first surface, the first projection extending from the vehicle component; a second projection having a second surface, the second projection extending from the first projection to define an angle of less than 180 degrees between the first surface and the second surface; and a recess located at the interface of the first and second surfaces. Optionally, at least a majority of the recess is located in one of the first or second surfaces. Advantageously, the recess has been found to reduce stress and strain acting on the bayonet connector. Specifically, since the surfaces are angled relative to each other, the interface (e.g. the corner) therebetween defines a region of increased stress of the bayonet connector. By incorporating a recess at this interface, the stress in this region can be reduced. In this way, the rigidity of the connection provided by the bayonet connector is improved, and thus vehicle electric drive unit components can be effectively secured. Optionally, the recess is fully located in one of the first or second surfaces. Advantageously, completely locating the recess in either the first or second surface has been found to further improve the stress characteristics of the bayonet connector (e.g. compared with providing the recess that extends over both surfaces). Optionally, at least a majority of the recess is located in the second surface. Advantageously, this has been found to significantly reduce the stress generated in the interface between the first and second surfaces. Optionally, the recess has a constant radius. This shape has been found to effectively improve the stress characteristics. Optionally, the recess defines a substantially circular arc in cross-section. Optionally, the recess defines an arc of a circle in cross-section, the circle having a radius of at least 0.4 mm; optionally, at least 0.5 mm; optionally, at least 0.6 mm; optionally, at least 0.75 mm. Advantageously, these dimensions allow the recess to provide effective stress reduction, while also not interrupting either surface to the extent that the bayonet connector works less effectively with the receiver. Optionally, the recess has a varying radius. Advantageously, a recess of varying radius has been found to be easily incorporated into the bayonet connector (e.g. via machining on a respective surface), whilst also reducing stress acting at the interface of the two surfaces. Optionally, the recess defines a part teardrop-shape or lachrymiform shape, in cross-section. Advantageously, this shape can be simply machined into the bayonet connector. Optionally, the recess defines a half teardrop-shape, or a half lachrymiform shape, in cross-section. Optionally, the radius of the recess varies between 0.5 mm and 5 mm. Optionally, the recess defines an arc of a circle having a diameter that is less than one third, optionally less than one quarter, optionally less than one fifth, optionally less than one eighth of the length or width of the projection into which the recess extends. The “length” may refer to an axial length, and the “width” may refer to a radial width. Optionally, the vehicle electric drive unit component is formed of metallic material, optionally steel or aluminium alloy material. This provides a robust electric drive unit component. Further, forming the bayonet connector from metallic material helps to provide a robust connection between the two vehicle electric drive unit components. Optionally, wherein the second projection extends from a free end of the first projection. This provides for a compact arrangement. Optionally, the first surface and the second surface define a substantially perpendicular angle therebetween. This provides for a vehicle component that is simple to manufacture and install, while being compact, making efficient use of regions in the vehicle electric drive unit in which space is limited. Optionally, wherein the vehicle component is a cover for at least partly covering an end of a different vehicle component. Optionally, wherein the vehicle component is a cooling fluid manifold for a stator core of an electric machine of a vehicle traction motor. Optionally, the vehicle electric drive unit component comprises a plurality of bayonet connectors. Optionally, the vehicle electric drive unit component comprises at least three, optionally at least four, optionally at least five, optionally at least six bayonet connectors. Having a plurality of bayonet connectors may provide a more robust connection between the components. A further aspect of the present disclosure provides an assembly for an electric drive unit of a vehicle, the assembly comprising: the vehicle electric drive unit component as disclosed herein; and a different vehicle electric drive unit component comprising at least one bayonet receiver for receiving a respective bayonet connector of the vehicle electric drive unit component such that the vehicle electric drive unit component is securable to the different vehicle electric drive unit component. Such an electric machine benefits from the advantages of the stator assembly outlined above. Moreover, the bayonet connector / receiver arrangement provides a simple means of securing two vehicle electric drive unit components together (e.g. by pushing and twisting the components relative to each other). Further, once connected, such a bayonet arrangement may be able to withstand greater axial separation forces than alternatives, such as snap-fit arrangements. Optionally, the vehicle electric drive unit component comprises a plurality of bayonet connectors, and wherein the different vehicle electric drive unit component comprises a corresponding plurality of bayonet receivers; optionally, wherein the vehicle electric drive unit component comprises at least three, optionally at least four, optionally at least five, optionally at least six bayonet connectors and wherein the different vehicle electric drive unit component comprises a corresponding number of bayonet receivers. Having a plurality of bayonet connectors and bayonet receivers may provide a more robust connection between the components. Optionally, the different vehicle electric drive unit component is a stator core for an electrical machine of a vehicle traction motor, the stator core comprising a first end, and wherein the vehicle electric drive unit component is a cover which at least partly covers the first end of the stator core. 2 Advantageously, the cover can be secured to the stator core via a simple arrangement without the need for additional fasteners (e.g. by pushing and twisting the cover and the stator core relative to each other). Further, it will be understood that because a stator core generally remains static within a housing of an electric machine (in contrast to the rotating rotor), use of the bayonet arrangement having a bayonet connector with improved stress characteristics may provide a suitably robust connection between the cover and the stator core. Further, because the bayonet connector(s) (e.g., projecting part(s) of the bayonet arrangement) are on the cover and the bayonet receiver(s) (e.g., recessed portion(s) of the bayonet arrangement) are on the stator core, the stator core can be produced via normal manufacturing techniques (e.g., as a stator lamination stack). In some embodiments, at least one bayonet connector is provided on the stator core, at least one bayonet connector on the cover, at least one bayonet receiver on the stator core, and at least one bayonet receiver on the cover. Optionally, the at least one bayonet receiver comprises an axial recess which extends axially inboard from the first end of the stator core, a circumferential recess which extends circumferentially from an axially inboard end of the axial recess, and an abutment surface positioned axially between the circumferential recess and the first end of the stator core. Optionally, the first projection of the at least one bayonet connector is an axial projection which extends from the cover and the second projection of the bayonet connector is a transverse projection which extends from a free end of the axial projection. In this way, the axial projection of the at least one bayonet connector can be pushed along the axial recess of the at least one bayonet receiver (e.g., by pushing the cover towards the stator core), the corresponding components can then be rotated so that the transverse projection of the at least one bayonet connector moves along the circumferential recess of the at least one bayonet receiver, so that the transverse projection engages the abutment surface to inhibit axial separation of the cover and stator core. Optionally, the axial and circumferential recesses comprise grooves in an outer radial surface of the stator core. This may be easier to manufacture than alternatives (e.g., internal bores within the stator core). Optionally, the grooves have a radially inner edge at a first radial dimension, and a radially outer edge at a second radial dimension, and wherein the stator core has a third radial dimension between the abutment surface and the first end of the stator core, wherein the third radial dimension is between the first and second radial dimensions. In this way, the first projection of the bayonet connector can extend over the abutment surface while remaining flush with an outer radial surface of the stator core. Optionally, the bayonet arrangement is configured so that cover is pushed axially towards the first end of the stator core to insert the or each bayonet connector into the corresponding bayonet receiver, and then twisted about a central axis of the cover and / or stator core to form an interlocking engagement between the or each bayonet connector and the corresponding bayonet receiver and thereby inhibit axial movement of the cover relative to the stator core. Optionally, the cover is twisted about the central axis of the different vehicle component in a clockwise direction with respect to the first end of the different vehicle component to form the interlocking arrangement. Optionally, the assembly comprises a seal positioned between the stator core and the cover, such that the seal is compressed therebetween by a respective bayonet connector and bayonet receiver. By compressing the seal with the bayonet arrangement, a contact pressure between the seal and the stator core and cover can be increased, which improves seal performance. For example, this may be useful when the cover is a cooling manifold which defines a chamber, whereby the seal is configured to seal an edge of the chamber. Optionally, a plurality of bayonet connectors and bayonet receivers are distributed circumferentially about the cover and stator core, respectively. Optionally, the bayonet connector and bayonet receiver are configured to withstand an axial separation force of at least 2kN, optionally at least 3kN, optionally at least 4kN, optionally at least 5kN. This provides a robust connection between the cover and the stator core. For example, this may be useful when the cover is a cooling manifold as the bayonet arrangement may be able to withstand a high pressure of cooling fluid inside within the cooling manifold, and / or a resilient force of a seal compressed between the stator core and the cover. Optionally, the stator core comprises a plurality of cooling passageways which extend in a longitudinal direction through the stator core away from the first end, and wherein the cover is a cooling manifold which defines at least one cooling channel in fluid communication with the cooling passageways. Such an arrangement allows the stator core to be cooled by passing a flow of cooling fluid through the cooling manifold and cooling passageways. Implementing such a bayonet connector in a cooling manifold ensures that the cooling manifold is robustly secured to the stator core to maintain effective cooling. Optionally, the at least one cooling channel comprises a chamber in fluid communication with the cooling passageways. Optionally, the cooling manifold further comprises a manifold inlet or manifold outlet for connecting the chamber to a cooling fluid circuit. Optionally, the at least one bayonet receiver may be machined into the stator core (e.g., into a stator lamination stack of identical layers, or into a forged / cast stator core). A further aspect of the present disclosure provides an electric machine comprising a assembly as disclosed herein. Such an electric machine benefits from the advantages of the stator assembly outlined above. The electric machine may be for driving one or more wheels of a vehicle. Optionally, the electric machine further comprises a housing having an axial end surface, wherein the assembly is positioned inside the housing with a first side of the cover facing the axial end surface of the stator core and a second side of the cover facing the axial end surface of the housing, and wherein the electric machine further comprises at least one further component positioned axially between the second side of the cover and the axial end surface of the housing. It will be understood that, in such an arrangement, because there is at least one further component positioned axially between the second side of the cover and the axial end surface of the housing (e.g., one or more busbars or other electrical components), the cover may not be easily clamped between the stator core and the housing. Therefore, having the cover secured to the stator core via the bayonet connector and receiver provides a secure connection between the cover and the stator core without having to modify the design or positioning of the at least one further component. A further aspect of the present disclosure provides a vehicle comprising an electric machine as disclosed herein. The electric machine may be arranged to drive one or more wheels of the vehicle. Such a vehicle benefits from the advantages of the assembly outlined above. According to a further aspect of the invention, there is provided a cooling fluid manifold for a stator core of an electric machine of a vehicle traction motor, the manifold comprising: a body; at least one bayonet connector for engaging a bayonet receiver of a stator core, wherein the at least one bayonet connector comprises: a first projection having a first surface, the first projection extending from the body; a second projection having a second surface, the second projection extending from the first projection to define an angle of less than 180 degrees between the first surface and the second surface; and a recess located at the interface of the first and second surfaces. Optionally, the recess is located in one of the first or second surfaces. The cooling fluid manifold benefits from the advantages of the vehicle electric drive unit component outlined above. The cooling fluid manifold may further comprise any of the features of the vehicle electric drive unit component described herein. According to a further aspect of the present disclosure, there is provided a bayonet connector for engaging a bayonet receiver, wherein the bayonet connector comprises: a first projection having a first surface; a second projection having a second surface, the second projection extending from the first projection to define an angle of less than 180 degrees between the first surface and the second surface; and a recess located at the interface of the first and second surfaces, wherein the recess is located in one of the first or second surfaces. The bayonet connector may further comprise any of the features of the bayonet connector described herein. A further aspect of the present disclosure provides a method of coupling a vehicle component to a different vehicle component, the method comprising: a) providing a vehicle component as herein set forth; b) providing a different vehicle component having a first end, the different vehicle component comprising at least one bayonet receiver; c) positioning the vehicle component against the first end of the different vehicle component; and d) securing the vehicle component to the different vehicle component via the at least one bayonet connector and bayonet receiver. Optionally, wherein step d) comprises pushing the vehicle component axially towards the first end and then twisting the vehicle component about a central axis of the vehicle component and / or the different vehicle component. Such a method provides a simple means of securing vehicle components (e.g., by pushing and twisting the components relative to each other). Optionally, the vehicle component and different vehicle components are vehicle electric drive unit components. Optionally, the different vehicle component is a stator core for an electrical machine of a vehicle traction motor, and the vehicle component is a cover which at least partly covers the first end of the stator core. Optionally, wherein the vehicle component is a cooling fluid manifold. It will be understood that because a stator core generally remains static within a housing of an electric machine (in contrast to the rotating rotor), use of the bayonet connectors and receivers may provide a robust connection between the cover and the stator 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 betaken 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 shows a vehicle according to an embodiment; Figure 2 shows a longitudinal cross-sectional view of an electric machine comprising a stator assembly according to an embodiment; Figure 3 shows a stator core and first cover of the stator assembly of Figure 2 in a disconnected state; Figure 4 shows the stator core and first cover of Figure 3 in a partially connected state; Figure 5 shows the stator core and first cover of Figures 3 and 4 in a secured state; Figure 6 shows a perspective view of a portion of a bayonet arrangement of the stator assembly of Figures 2 to 5; Figure 7 shows a cross-sectional view of the portion of the bayonet arrangement of Figure 6; Figure 8 shows a perspective view of a portion of a vehicle electric drive unit component according to an embodiment; Figure 9A shows a cross-sectional view of the vehicle electric drive unit component of Figure 8; Figure 9B to 9F show cross-sectional views of the vehicle electric drive unit component according to different embodiments; and Figure 10 shows a flow chart of a method of coupling a vehicle component to a different vehicle component according to an embodiment. DETAILED DESCRIPTION Examples of the present disclosure relate to a vehicle electric drive unit component having at least one bayonet connector for engaging a bayonet receiver of a different vehicle electric drive unit component. As will be discussed below, the vehicle electric drive unit component may be a cover or a cooling fluid manifold and the different vehicle electric drive unit component may be a stator core for an electrical machine of a vehicle traction 5 motor. While the discussion below primarily refers to components of a stator assembly, it will be appreciated that the vehicle electric drive unit component may be in any suitable form, and may be configured for connecting to any different component in a vehicle electric drive unit. Examples of the present invention relate to a stator assembly for an electric machine of a vehicle traction motor. Such an electric machine may be of a synchronous type or asynchronous type, for example a permanent magnet synchronous motor. Non-limiting examples will now be described with reference to accompanying Figures 1 to 10, where the figures illustrate a stator assembly 10, a stator core 12, cover 30A, 30B, an electric machine 100, an electric drive unit (EDU) 160 and a vehicle 200. Figure 1 illustrates a vehicle 200 having a first electric machine 100-1 which is part of a vehicle traction motor for driving one or more front wheels of the vehicle 200. The vehicle 200 also has a second electric machine 100-2 which is part of a vehicle traction motor for driving one or more rear wheels of the vehicle 200. In other embodiments the vehicle 200 may comprise only a single electric machine 100, which is part of a vehicle traction motor, arranged or configured to drive one or more front wheels of the vehicle 200 and / or one or more rear wheels of the vehicle 200. At a vehicle axle the electric machine 100 may be arranged to drive both wheels, either directly or through other transmission components. In other arrangements there may be more than one electric machine 100 arranged to provide torque to a vehicle axle, for example, to provide torque vectoring functionality for the vehicle 200. Other arrangements may have one electric machine 100 arranged or configured to drive each wheel of the vehicle 200. The electric machine 100 comprised in the vehicle 200 may have a stator assembly 10 as described herein. For example, the electric machine 100 comprised in the vehicle 200 may be the electrical machine of Figure 2, described below. As illustrated schematically on Figure 1, the electric machine(s) 100 may be part of an electric drive unit (EDU) 160. For example, the EDU may include transmission components, lubrication and cooling components, and / or power electronics, in addition to the electric machine 100. In the vehicle 200 of Figure 1, the first electric machine 100-1 is part of a first EDU 160-1 for driving front wheels of the vehicle 200, and the second electric machine 100-2 is part of a second EDU 160-2 for driving rear wheels of the vehicle 200. Referring to Figure 2, the electric machine 100 of the vehicle 200 is illustrated. The electric machine includes a stator assembly 10 which has an annular stator core 12. The stator core 12 has a cylindrical inner channel or cavity 14, which defines a central stator axis 16. The cylindrical inner channel 14 extends in a direction parallel to the central stator axis 16 from a first axial end surface 18 of the stator core 12 to a second axial end surface 20 of the stator core 12. The stator core 12 has a plurality of winding slots 22 extending radially to support electrical stator windings (not shown). A plurality of stator teeth (not shown) are provided between the winding slots 22. In other words, stator teeth are interspersed between the winding slots 22 in a circumferential direction about the stator core 12. Both the plurality of winding slots 22 and the plurality of stator teeth extend from the first axial end surface 18 to the second axial end surface 20 of the stator core 12. The electric machine 100 also includes a rotor 112. The rotor 112 is configured to fit within the cylindrical inner channel 14 of the stator core 12 with a small air gap 26 therebetween. The outside surface of the rotor 112 provides a surface concentric with a circumference of the cylindrical inner channel 14, such that as the rotor 112 rotates within the cylindrical inner channel 14 of the stator core 12, a consistent air gap 26 is maintained between the rotor 112 and the stator core 12. The electric machine 100 may have forty-eight winding slots 22 and eight rotor poles. Other combinations of winding slot numbers and rotor pole numbers are useful. As shown in Figure 2, the electric machine 100 has a housing 102 surrounding the stator assembly 10. In some embodiments the housing 102 is a cylindrical housing, though it will be understood that the stator core 12 may have a non-circular cross section, in particular where the outer form of the stator core 12 is oblate or has projections thereon, such that the housing 102 may be non-circular. The stator core 12 has a plurality of cooling passageways 28 which extend in a longitudinal direction (i.e., in a direction parallel to the central stator axis 16) through the stator core 12 away from the first end 18 of the stator core 12. In particular, the cooling passageways 28 extend from the first axial end surface 18 to the second axial end surface 20 of the stator core 12. The cooling passageways 28 are distributed about a circumference of the stator core 12. The electric machine 100 has a first cover 30A which at least partly covers the first axial end surface 18 of the stator core 12. In the illustrated embodiment, the first cover 30A is a first cooling manifold. The first cooling manifold 30A defines at least one cooling channel 32A in fluid communication with the plurality of the cooling passageways 28. In the illustrated embodiment, the at least one cooling channel 32A defines a first chamber 32A in fluid communication with the plurality of cooling passageways 28. The first cooling manifold 30A also defines a manifold inlet 34A for connecting the first chamber 32A to a cooling fluid source. In this way, cooling fluid may pass through the manifold inlet 34A, into the first chamber 32A and then through the cooling passageways 28. In the arrangement of Figure 2, the manifold inlet 34A is defined by a radially outer edge of the first cooling manifold 30A, which is open to the housing 102 so that cooling fluid can enter the first chamber 32A through a first opening 104 in the housing 102. In other words, a radially outer edge 36A of the first chamber 32A is defined by the housing 102. The electric machine 100 also has a second cover 30B which at least partly covers the second axial end surface 20 of the stator core 12. In the illustrated embodiment, the second cover 30B is a second cooling manifold. The second cooling manifold 30B defines at least one cooling channel 32B in fluid communication with the plurality of cooling passageways 28. In the illustrated embodiment, the at least one cooling channel 32B is a second chamber 32B in fluid communication with the plurality of cooling passageways 28. The second cooling manifold 30B also defines a manifold outlet 34B for expelling cooling fluid from the second chamber 32B. In this way, cooling fluid may pass through the manifold inlet 34A into the first chamber 32A of the first cooling manifold 30A, through the plurality of cooling passageways 28 to the second chamber 32B and then out of the manifold outlet 34B. In the arrangement of Figure 2, the manifold outlet 34B is defined by a radially outer edge of the second cooling manifold 30B, which is open to the housing 102 so that cooling fluid can be expelled from the second chamber 32B through a second opening 106 in the housing 102. In other words, a radially outer edge 36B of the second chamber 32B is defined by the housing 102. It will be understood that, although the schematic arrows on Figure 2 show a flow of cooling fluid through the first opening 104 in the housing, through the first cooling manifold 30A, along the cooling passageways 28, into the second cooling manifold 30B and then out of the second opening 106 in the housing 102, the flow of cooling fluid could be reversed. In other words, cooling fluid could instead flow through the second opening 106 in the housing 102, through the second cooling manifold 30B, along the cooling passageways 28, into the first cooling manifold 30A and then out of the first opening 104 in the housing 102. In such a configuration, the manifold inlet 34A of the first cooling manifold 30A would instead be a manifold outlet, and similarly the manifold outlet 34B of the second cooling manifold 30B would instead be a manifold inlet. In the illustrated arrangement, the first and second cooling manifolds 30A, 30B are annular. In this way, the first and second chambers 32A, 32B are also annular. The first and second cooling manifolds 30A, 30B can be considered as part of the stator assembly 10, along with the stator core 12. In the illustrated embodiment, the housing 102 of the electric machine 100 has a first axial end surface 102A and a second axial end surface 102B. The stator assembly 10 is positioned inside the housing 102 so that a first side of the first cooling manifold 30A faces the first axial end surface 18 of the stator core 12 and a second side of the first cooling manifold faces the first axial end surface 102Aofthe housing 102. Similarly, a first side of the second cooling manifold 30B faces the second axial end surface 20 of the stator core 12, and a second side of the second cooling manifold 30B faces the second axial end surface 102B of the housing 102. In the illustrated embodiment, the second side of the second cooling manifold 30B is provided adjacent to the second axial end surface 102B of the housing 102. On the contrary, although the second side of the first cooling manifold 30A faces the first axial end surface 102A of the housing 102, the first cooling manifold 30A is not provided adjacent to the first axial end surface 102A of the housing 102. In other words, the first cooling manifold 30A is spaced apart from the first axial end surface 102A of the housing 102 in an axial direction. In addition, at least one further component 114 of 7 the electric machine 100 is positioned axially between the second side of the first cooling manifold 30A and the first axial end surface 102A of the housing 102 (as illustrated schematically on Figure 2). It will be understood that, in such an arrangement, because there is at least one further component 114 (e.g., one or more busbars or other electrical components) positioned axially between the first cooling manifold 30A and the first axial end surface 102A of the housing 102, the first cooling manifold 30A may not be easily clamped between the first axial end surface 18 of the stator core 12 and the housing 102. Therefore, the first cooling manifold 30A may be secured to the stator core 12 by an interlocking arrangement (e.g., as described in detail below with reference to Figures 3 to 9F) to provide a secure connection between the stator core 12 and first cooling manifold 30A, without having to modify the design or positioning of the at least one further component 114. The electric machine 100 of Figure 2 also has a cooling fluid recirculation system 120 which is configured to supply cooling fluid to the manifold inlet 34A of the first cooling manifold 30A in a cooling fluid recirculation circuit 122 (i.e., via the first opening 104 in the housing 102). The stator core 12 is defined by a stator lamination stack 44. In other words, the stator core 12 is formed of a plurality of layers. The layers are stacked one atop the other to form the stator lamination stack 44, which extends from the first axial end surface 18 of the stator core 12 to the second axial end surface 20 of the stator core 12. The layers may be stamped from sheet material (e.g., sheet metal), or formed via any other suitable process. In this way, a stator core 12 having a complex cross-sectional shape can be formed. In some arrangements the cooling passageways 28 are coated on their inner surfaces, for example with a plastic material, to provide sealing such that coolant is prevented, or resisted, from passing between the laminations of the stator lamination stack 44 under the temperatures and pressures described herein. There are different methods for producing this arrangement. The plastic may be applied to the inner surface of the cooling passageway 28 by flowing the thermoplastic through the cooling passageway 28, or by inserting a formed thermoplastic tube into the cooling passageway 28 and optionally applying pressure to the tube to blow mould the tube to the shape of the cooling passageway 28. The thermoplastic may have a complex cross-sectional shape either internally and / or externally. The external surface of the thermoplastic tube may have a simple rounded shape and the inner surface of the cooling passageway 28 may be similarly rounded. Once the plastic coating is in place the thickness of the coating of the inner surface of the cooling passageways 28 is in the region of 0.5mm, but other thicknesses are useful. The thermal conductivity of the plastic material is in the range 1 to 40 watts / mK. The functioning of electrical machines 100 and electric drive units (EDUs) 160 is known, and so will not be described here in more detail. In the arrangement of Figure 2, a first axial seal 40A is located between the first end 18 of the stator core 12 and the first cooling manifold 30A to seal a radially inner edge 38A of the first chamber 32A. In particular, the first axial seal 40A is an annular seal. The first axial seal 40A is located in a first annular recess 42A in the first cooling manifold 30A, which locates the first axial seal 40A in the correct position. Similarly, a second axial seal 40B is located between the second end 20 of the stator core 12 and the second cooling manifold 30B to seal a radially inner edge 38B of the second chamber 32B. In particular, the second axial seal 40B is an annular seal. The second axial seal 40B is located in a second annular recess 42B in the second cooling manifold 30B, which locates the second axial seal 40B in the correct position. Similarly, a third axial seal 40C is provided at an opposite side of the second cooling manifold 30B to the second axial seal 40B. The third axial seal 40C is configured to form a seal between the second cooling manifold 30B and the second axial end surface 102B of the housing 102. The third axial seal 40C is located in a third annular recess 42C in the second cooling manifold 30B, which locates the third axial seal 40C in the correct position. In the arrangement of Figure 2, a radial seal 41 is located between the radially outer edge 36A of the first cooling manifold 30A and a radial inner surface of the housing 102. In particular, the radial seal 41 is an annular seal (e.g., an O-ring). The radial seal 41 is located in a fourth annular recess 43 in the radially outer edge 36A of the first cooling manifold 30A, which locates the radial seal 41 in the correct position. In this context, the term “axial seal” will be understood to mean a seal which is configured to have compression applied to axial ends of the seal’s cross-section. Conversely, the term “radial seal” will be understood to mean a seal which is configured to have compression applied to the inner and outer radial surfaces of the seal. Often, axial seals have a cross-section which is elongate in the axial direction, although this is not always the case. Referring now to Figures 3 to 9F, the vehicle electric drive unit component will be described in more detail. In Figures 3 to 8, the vehicle electric drive unit component is the first cover 30A of the stator assembly 10. The vehicle electric drive unit component 30A is configured to connect with a different 8 vehicle drive unit component. In the figures, the different vehicle drive unit component is the stator core 12. It will be appreciated that the vehicle electric drive unit component and the different vehicle drive unit component may be any components of a vehicle electric drive unit that are intended to be connected together. In the illustrated arrangement, the stator assembly 10 includes the vehicle electric drive unit component in the form of the first cover 30A which, in this embodiment, is a first cooling manifold 30A. The stator assembly 10 also includes the different vehicle electric drive unit component in the form of the stator core 12. The first cooling manifold 30A is intended to cover the first axial end surface 18 of the stator core 12. As can be seen in the figures, the vehicle electric drive unit component (e.g. the cooling fluid manifold 30A) includes at least one bayonet connector 52. The at least one bayonet connector 52 is configured to engage with a bayonet receiver 54 of a different vehicle electric drive unit component, e.g. at least one bayonet receiver 54 on the stator core 12. The bayonet arrangement includes the at least one bayonet connector 52 on the first cooling manifold 30A and at least one bayonet receiver 54 on the stator core 12. In the figures, a plurality of bayonet connectors 52 are provided on the first cooling manifold 30A and corresponding plurality of bayonet receivers 54 are provided on the stator core 12. In the illustrated embodiment, the plurality of bayonet connectors 52 and bayonet receivers 54 are distributed circumferentially about the stator core 12 and the first cooling manifold 30A. In the illustrated embodiment, the first cooling manifold 30A includes six bayonet connectors 52, and the stator core 12 includes six bayonet receivers 54. However, in other embodiments there may be a different number of bayonet connectors 52 and bayonet receivers 54 (e.g., one, two, three, four, five, or greater than six). In some arrangements, the bayonet connectors 52 are evenly spaced apart about the vehicle electric drive unit component. For example, in arrangements in which the vehicle electric drive unit component is an annular cooling fluid manifold 30A, the plurality of bayonet connectors 52 may be evenly distributed about the circumference of the annular cooling fluid manifold 30A. The arrangement of the bayonet connectors 52 and receivers 54 may be referred to as a first interlocking arrangement 50 of the stator core 12. The first interlocking arrangement 50 is configured to secure the first cooling manifold 30A to the stator core 12. The bayonet connectors 52 and receivers 54 provides a simple means of securing without the need for additional fasteners. Further, it will be understood that because the stator core 12 generally remains static within the housing 102 (in contrast to the rotating rotor 112), use of such an interlocking arrangement 50 may provide a suitably robust connection between the first cooling manifold 30A and the stator core 12. In the illustrated embodiment, the first axial seal 40A, which is positioned between the stator core 12 and the first cooling manifold 30A, is compressed therebetween by the first interlocking arrangement 50. By compressing the first axial seal 40A with the first interlocking arrangement 50, a contact pressure between the first axial seal 40A and the stator core 12 and first cooling manifold 30A can be increased, which improves seal performance. In other words, the pressure of cooling fluid inside the first chamber 32A can be increased. As best illustrated in Figures 3 to 9E, the first interlocking arrangement 50 is a bayonet arrangement, e.g including the bayonet connectors) 52 and the bayonet receiver(s) 54. Such a bayonet arrangement 50 provides a simple means of securing the first cooling manifold 30A to the stator core 12 (e.g., by pushing and twisting the first cooling manifold 30A and stator core 12 relative to each other). Further, once connected such a bayonet arrangement 50 may be able to withstand greater axial separation forces than alternatives, such as snap-fit arrangements. In some embodiments, the bayonet arrangement 50 is configured to withstand an axial separation force of at least 2kN (e.g., at least 3kN, at least 4kN, or at least 5kN). This provides a robust connection which may be able to withstand a high pressure of cooling fluid inside within the first cooling manifold 30A, and / or a high resilient force of the first axial seal 40A compressed between the stator core 12 and the first cooling manifold 30A. It will be understood that such an axial separation force may be achieved by forming the stator core 12 and first cooling manifold 30A from particular materials (e.g., metallic materials such as steel or aluminium alloy material). It will be understood that such an axial separation force may also be achieved by selecting an appropriate number of bayonet connectors and bayonet receivers (described below), and or by sizing and shaping the bayonet connectors and bayonet receivers to withstand such an axial separation force. Locating the bayonet receivers 54 (e.g., recessed portions of the bayonet arrangement 50) on the stator core 12, allows the stator core 12 to be produced via normal manufacturing techniques (e.g., as a stator lamination stack 44). However, in alternative embodiments, the bayonet arrangement 50 includes at least one bayonet connector 52 on the stator core and at least one bayonet receiver 54 on the first cooling manifold 30A. For example, the bayonet connectors 52 and bayonet receivers 54 may be reversed. Put another way, the vehicle electric drive unit component may be the stator core 12 and the different vehicle electric drive unit component may be the cover and / or manifold 30A. Alternatively, there may be at least one bayonet connector 52 on the stator core 12, at least one bayonet connector 52 on the first cooling manifold 30A, at least one bayonet receiver 54 on the stator core 12, and at least one bayonet receiver 54 on the first cooling manifold 30A. In other words, both the cooling manifold 30A and stator core 12 may have a bayonet receiver 54 which is engaged by a bayonet connector 52 of the other component, and bayonet connector 52 which engaged a bayonet receiver of the other component. In some embodiments, the bayonet arrangement 50 includes at least one bayonet receiver 54 on the stator core 12, and at least one bayonet receiver 54 on the first cooling manifold 30A. In such embodiments, the bayonet arrangement 50 may further include an intermediate component (not shown). In such embodiments, the intermediate component may include at least one bayonet connector 52 for connecting to the at least one bayonet receiver 54 of the stator core 12, and at least one bayonet connector 52 for connecting to the at least one bayonet receiver 54 of the first cooling manifold 30A. It will be understood that, regardless of the particular construction of the bayonet arrangement 50, the bayonet arrangement 50 may be configured so that the first cooling manifold 30A is pushed axially towards the first axial end surface 18 of the stator core 12 to insert the bayonet connectors into the corresponding bayonet receivers 54. This is illustrated in the transition of the first cooling manifold 30A between Figures 3 and 4. The first cooling manifold 30A may then be twisted about a central axis of the first cooling manifold 30A (i.e., an axis which is coaxial with the central axis 16 of the stator core 12) to form an interlocking engagement between the bayonet connectors 52 and the corresponding bayonet receivers 54. This is illustrated in the transition of the first cooling manifold 30A between Figures 4 and 5. It will be understood that once the first cooling manifold 30A has been pushed and twisted about the central axis 16, the interlocking engagement between the bayonet connectors 52 and bayonet receivers 54 inhibits axial movement of the first cooling manifold 30A relative to the stator core 12. In other words, this interlocking engagement allows the bayonet arrangement 50 to withstand an axial separation force (e.g., caused by resilient compression of the first axial seal 40A and / or a pressure of cooling fluid inside the first chamber 32A). In the illustrated embodiment, the first cooling manifold 30A is twisted about the central axis 16 in an anti-clockwise direction with respect to the first axial end surface 18 of the stator core 12 to form the interlocking engagement. In alternative embodiments, the first cooling manifold 30A is twisted about the central axis 16 in the opposite direction to form the interlocking engagement. It will be understood that the stator core 12 and first cooling manifold 30A are static components within the housing 102 of the electric machine 100. In other words, they are not susceptible to relative rotation as part of normal use of the electric machine 100 (in comparison to the rotor 112, or other “rotating” components of the electric machine 100). In any case, movement of the bayonet arrangement 50 from the state illustrated in Figure 5 to the state illustrated in Figure 4 (e.g., via rotation about the central axis 16 in a clockwise direction with respect to the first axial end surface 18 of the stator core 12) is inhibited by friction between the corresponding bayonet connectors 52 and bayonet receivers 54. This friction is increased by the biasing force caused by compression of the first axial seal 40A between the stator core 12 and the first cooling manifold 30A, which acts to urge the first cooling manifold 30A and stator core 12 away from each other. During use, a further biasing force in the form of pressurised cooling fluid inside the first chamber 32A of the first cooling manifold 30A also acts to urge the first cooling manifold 30A and stator core 12 away from each other. This further increases the friction between the bayonet connectors 52 and bayonet receivers 54 to inhibit relative rotation between the stator core 12 and the first cooling manifold 30A. In some embodiments, the bayonet connectors 52 and bayonet receivers 54 are configured so that a further interlocking engagement is formed therebetween to inhibit relative rotation of the stator core 12 and first cooling manifold 30A (e.g., in addition to friction). In such embodiments, the first cooling manifold 30A may be pushed in a first axial direction towards the first axial end surface 18 of the stator core 12, twisted about the central axis of the first cooling manifold 30A to form the interlocking engagement which inhibits axial separation, and then pushed in a second axial direction opposite to the first axial direction to form the further interlocking engagement which inhibits rotation. Pushing in the second axial direction may be 10 achieved by a biasing force (e.g., caused by compression of the first axial seal 40A, pressurised cooling fluid inside the first chamber 32A, and / or a spring or other biasing element), to keep the further interlocking engagement in an engaged state. In some embodiments, after the bayonet connectors 52 and bayonet receivers 54 have formed an interlocking engagement (as illustrated in Figure 5) an additional locking component may be used to inhibit relative rotation between the stator core 12 and the first cooling manifold 30A (e.g., a pin or grub screw, for example, passing radially through a bayonet connector 52 and an adjacent portion of the stator core 12). As best illustrated in Figures 6 and 7, the at least one bayonet receiver 54 of the stator core 12 has an axial recess 56 which extends axially inboard from the first axial end surface 18 of the stator core 12, a circumferential recess 58 which extends circumferentially from an axially inboard end 60 of the axial recess 56, and an abutment surface 62 positioned axially between the circumferential recess 58 and the first axial end surface 18 of the stator core 12. The at least one bayonet connector 52 of the cooling fluid manifold 30A has a first projection 64 that extends from the first cooling fluid manifold 30A, and a second projection 66 that extends from the first projection 64. The first projection 64 has a surface 64A and the second projection 66 has a surface 66A. The second projection 66 extends relative to the first projection 64 so as to define an angle of less than 180 degrees between the first surface 64A and the second surface 66A. In the illustrated arrangement, the first surface 64A and the second surface 66A define a substantially perpendicular angle therebetween, but it will be appreciated that other angles may be envisaged (e.g. that correspond to the configuration of corresponding bayonet receivers 54). The first projection 64 extends from the manifold 30A so as to define a substantially perpendicular angle between the first surface 64A and a respective surface of the manifold 30A in the figures. In this way, the first projection 64 can be seen as an axial projection that extends axially from a first axial surface of the first cooling fluid manifold 30A, and the second projection 66 can be seen as a transverse projection. It will be appreciated that the projections 64,66 may define different angles therebetween, as well as between the first projection 64 and the cooling fluid manifold 30A. The second projection 66 may extend from a free end 68 of the first projection 64. The connector 52 may define a substantially L-shape in cross-section. In the figures, the first surface 64A is an axially inner surface of the connector 52 and the second surface 66A is a radially inner surface of the connector 52, e.g. the two surfaces are adjacent on another. The first and second projections 64, 66 may be integrally formed, or formed separately and connected (e.g. via adhesive). The first projection 64 of the or each bayonet connector 52 can be pushed along the axial recess 56 of the or each bayonet receiver 54 (e.g., by pushing the first cooling manifold 30A towards the stator core 12). The corresponding components can then be rotated so that the second projections 66 of the bayonet connectors 52 move along the circumferential recesses 58 of the bayonet receivers 54, so that the second projections 66 engage the abutment surfaces 62 to inhibit axial separation of the first cooling manifold 30A and the stator core 12. In the illustrated embodiment, the axial recesses 56 and circumferential recesses 58 are grooves in an outer radial surface 70 of the stator core 12. In alternative embodiments, the axial recesses 56 and / or circumferential recesses 58 are internal bores within the stator core 12. As best illustrated in Figure 7, the axial recesses 56 and circumferential recesses 58 have a radially inner edge 72 at a first radial dimension, and a radially outer edge 74 at a second radial dimension. The stator core 12 has a third radial dimension between the abutment surfaces 62 and the first axial end surface 18 of the stator core 12, which is between the first and second radial dimensions. In this way, the first projections 64 of the bayonet connectors 52 can extend over the abutment surfaces 62 while remaining flush with the outer radial surface 70 of the stator core 12. Put another way, there is an intermediate step 76 between each abutment surface 62 and the first axial end surface 18 of the stator core 12. The intermediate step 76 does not extend radially to the outer radial surface 70 of the stator core 12. It will be appreciated that the bayonet connector(s) 52 on the vehicle electric drive unit component must be suitably resistant to significant deformation to maintain an effective connection between the components. This is particularly important in arrangements in which the component, and thus bayonet connector(s) 52, are subjected to high loads and temperatures that may cause deformation. It will be appreciated that the vehicle electric drive unit component may be exposed to high pressures and / or high temperatures during operation of the vehicle 200. For example, the component may be a cooling fluid manifold 30A exposed to temperatures in the range of 80 to 100 degrees Celsius, for example, 90°C, and pressures in the range of 3 to 4 bar, for example 3.2 bar. It has been found that the interface between the first surface 64A and the second surface 66A is a region that is particularly susceptible to elevated stress and strain, increasing the risk of the bayonet connector 52 becoming fatigued or failing. For this reason, the or each bayonet connector 52 includes a recess 78 located at the interface of the first surface 64A and the second surface 66A. The recess 78 is configured to reduce stress and strain acting on the bayonet connector 52. Incorporating the recess 78 between the surfaces 64A, 66A reduces the stress and strain at the interface of the two projections 64, 66 and thereby improves the rigidity of the bayonet connector 52. This results in a more secure connection between a vehicle electric drive unit component and a different vehicle electric drive unit component. The recess 78 may extend across the inner edge defined by the interface between the first surface 64A and the second surface 66A. In this way, the first surface 64A transitions to the second surface 66A via the recess 78, e.g. the recess 78 replaces a corner between the two surfaces. The recess 78 may extend along the entire thickness of the respective connector 52, e.g. completely across the inner edge. In arrangements in which the vehicle electric drive unit component defines a curved shape (e.g. an annular shape), the thickness of the connector 52 is defined in a circumferential direction. Figures 9A to 9F indicate various configurations of the recess 78. The connectors 52 indicated in these figures are substantially the same, with only the configuration of the recess 78 being different. At least a majority of the recess 78 is located in one of the first or second surfaces 64A, 66A. This is in contrast to locating the recess substantially equally in both the first and second surfaces 64A, 66A (e.g. as is indicated in Figure 9E). Locating the majority of the recess 78 in either the first surface 64A or the second surface 66A has been found to improve the stress characteristics of the bayonet connector 52 compared with locating a recess 78 equally in both the first and second surfaces 64A, 66A. It has been found that locating at least a majority of the recess 78 in the second surface 66A (e.g. as shown in Figures 9B and 9D) results in a significant reduction in the connector 52 being subject to high stress. It should be appreciated that at least a majority of the recess 78 may be located in the first surface 64A in some arrangements. It will be understood that the term “majority of the recess” relates to the volume of space or cut-out defined by the recess 78. A majority of the recess therefore refers to more than half of the volume defined by the recess 78 being located in the first surface 64A or the second surface 64B. Figures 9A to 9D indicate examples of bayonet connectors 52 in which the recess 78 is fully located in one of the first or second surfaces 64A, 66A (e.g. in only one surface and not extending over both surfaces). This arrangement has been found to further improve the stress characteristics of the bayonet connector 52 compared with providing a recess that extends over both surfaces. In Figures 9A and 9C, the recess 78 is completely located in the first surface 64A, while Figures 9B and 9D indicate the recess 78 completely located in the second surface 66A. The recess 78 may define a curved inner surface. Referring to Figures 9A and 9B, the recess 78A defines a substantially circular arc in cross-section (e.g. as viewed in Figures 9A to 9F). The recess 78A has a constant radius. The recess 78A defines an arc of a circle in cross-section. The recess 78A may define a substantially semi-circular shape in cross-section. The recess 78A may define an arc of a circle having a diameter that is less than one third, optionally less than one quarter, optionally less than one fifth, optionally less than one eighth of the length or width of the projection 64, 66 into which the recess 78A extends. In embodiments where the vehicle electric drive unit is the cooling fluid manifold 30A, the “length” may refer to an axial length, and the “width” may refer to a radial width. The recess 78A can provide effective stress reduction to the connector 52 without significantly reducing the length and / or width thereof, maintaining an effective robustness of the connector. The recess 78A may define an arc of a circle having a radius of at least 0.4 mm, optionally, at least 0.5 mm, optionally, at least 0.6 mm, and optionally, at least 0.75 mm. Such dimensions may be particularly advantageous in arrangements in which the vehicle electric drive unit component is the fluid manifold 30A. Referring to Figures 9C and 9D, the recess 78B has a varying radius. The recess 78B changes radius as it extends over a respective surface 66A, 66B. In the figures, the recess 78B defines a part teardrop shape or a lachrymiform shape in cross-section. The recess 78B may define a half teardrop shape or a half lachrymiform shape. In alternative arrangements, the recess 78B may define an oval shape or a part oval shape. The recess 78B may define a shape having a maximum diameter that is less than one third, optionally less than one quarter, optionally less than one fifth, and optionally less than one eighth of the length or width of the projection 64, 66 into which the recess 78B extends. The recess 78B may define a radius that varies between 0.5 mm and 5 mm. Such dimensions may be particularly advantageous in arrangements in which the vehicle electric drive unit component is a fluid manifold 30A. Figure 9E indicates an alternative arrangement of the recess 78. In the figure, the recess 78C is located in both the first and second surfaces 64A, 66A. The recess 78C defines an arc of a circle in cross-section. The recess 78C defines approximately three-quarters of a circle in cross-section. Figure 9F indicates an alternative arrangement of the recess 78. In this figure, the recess 78D is located in both the first and second surfaces 64A, 66A. The recess 78D defines a part teardrop or lachrymiform shape in each of the first and second surfaces 64A, 66A. The part teardrop in each of the surfaces 64A, 66A conjoins to form a continuous recess 78D extending into both surfaces 64A, 66A. The recess 78D defines a half teardrop shape or a half lachrymiform shape in each surface 64A, 66A. In alternative arrangements, the recess 78D may define an oval shape or a part oval shape. It will be appreciated that the recess 78 may be any suitable shape and configuration. For example, in other arrangements, the recess 78 may not define a linear shape, and may include curves of differing diameters and / or include linear regions and curved regions. The vehicle electric drive unit component may be formed of metallic material, optionally steel or aluminium alloy material. This provides a robust electric drive unitcomponentcapableof forming a robust connection. In some arrangements, the vehicle electric drive unit component may be formed of plastic material. In some arrangements, the second cooling manifold 30B may be the vehicle electric drive unit component. Such an arrangement provides a simple means of securing the second cooling manifold 30B to the stator core 12 without the need for additional fasteners. In such an arrangement, the second axial seal 40B, which is positioned between the stator core 12 and the second cooling manifold 30B, is compressed therebetween by the bayonet connector and receiver arrangement. By compressing the second axial seal 40B, a contact pressure between the second axial seal 40B and the stator core 12 and second cooling manifold 30B can be increased, which improves seal performance. In other words, the pressure of cooling fluid inside the second chamber 32B can be increased. It will be understood that the second axial seal 40B may be further, or alternatively, be compressed due to the second cooling manifold 30B being clamped between the second axial end surface 102B of the housing 102, and the second axial end surface 20 of the stator core 12. Alternatively, the second cooling manifold 30B may be coupled to the stator core 12 via an alternative interlocking arrangement, e.g. a snap-fit arrangement. Such a snap-fit arrangement allows the second cooling manifold 30B to be secured to the stator core 12 simply by pushing the second cooling manifold 30B towards the second axial end surface 20 of the stator core 12. It will be understood that although the vehicle electric drive unit component having the bayonet connectors 52 is described above as being a cover or cooling fluid manifold 30A for a stator core 12, the vehicle electric drive unit component may be another component, e.g. for connecting to a stator core 12 or another component in the vehicle electric drive unit. For example, in some embodiments, the vehicle electric drive unit component may be: a wire harness for electrical windings, power electronics, another type of cooling component, a lubrication or bearing component, a transmission component, a housing component, or any other electric machine component or electric drive unit component. For example, any of the components mentioned may be formed as a cover which at least partially covers a portion of the stator core 12 (e.g., one of the axial end surfaces 18, 20), regardless of any other functionality that the components perform. In some cases, the vehicle electric drive unit component may be the stator core 12 (e.g. having the bayonet connectors 52), and the different vehicle electric drive unit component may be any component to be connected to the stator core 12, having corresponding bayonet receivers 54. It will be understood that the vehicle electric drive unit component may be any component in the electric drive unit 160 of a vehicle 200 that is intended to be connected to another component. Although the bayonet connector 52 has been described in the context of vehicle electric drive unit components, it will be appreciated that the bayonet connector 52 described herein is suitable for any use in connecting one part with another. For example, the bayonet connector 52 may be implemented in electronics and electrical components, e.g. for connecting antennas, cables, power cords, sensors, communications equipment, or the like. The 13 bayonet connector 52 may be further implemented in control devices, e.g. connecting probes, sensors, cables. The bayonet connector 52 may be utilised in other vehicle components (e.g. external to the electric drive unit), for example, in connecting sensors, lights, electrical systems or the like. It is envisaged that the bayonet connector 52 may be suitable for use in any application in which a simple and robust connection that has suitable stress and / or strain characteristics to withstand various temperature and pressure fluctuations is required. A method of coupling a vehicle component to a different vehicle component is illustrated in Figure 10. The method includes the following steps: a) providing a vehicle component having at least one bayonet connector 52 as has been described; b) providing a different vehicle component having a first end, the different vehicle component having at least one bayonet receiver 54; c) positioning the vehicle component against the first end of the different vehicle component; and d) securing the vehicle component to the different vehicle component via the at least one bayonet connector 52 and bayonet receiver 54. In some embodiments, step d) includes pushing the vehicle component axially towards the first end and then twisting the vehicle component about a central axis of the vehicle component and / or the different vehicle component. The vehicle component and the different vehicle component may be vehicle 200 electric drive unit 160 components. The different vehicle component may be a stator core 12 for an electrical machine 100 of a vehicle traction motor, and the vehicle component is a cover 30A which at least partly covers the first end 18 of the stator core 12. The central axis may be the central axis 16 of the cover 30A and / or stator core 12. The vehicle component may be a cooling fluid manifold 30A, It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. It should also be noted that whilst the appended claims set out particular combinations of features described above, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed.

Claims

1. A vehicle electric drive unit component comprising at least one bayonet connector for engaging a bayonet receiver of a different vehicle electric drive unit component, wherein the at least one bayonet connector comprises:a first projection having a first surface, the first projection extending from the vehicle component;a second projection having a second surface, the second projection extending from the first projection to define an angle of less than 180 degrees between the first surface and the second surface; anda recess located at the interface of the first and second surfaces, wherein at least a majority of the recess is located in one of the first or second surfaces.

2. The vehicle electric drive unit component according to claim 1, wherein the recess is fully located in one of the first or second surfaces.

3. The vehicle electric drive unit component according to claim 1 or claim 2, wherein at least a majority of the recess is located in the second surface.

4. The vehicle electric drive unit component according to any preceding claim, wherein the recess has a constant radius.

5. The vehicle electric drive unit component according to any of claims 1 to 3, wherein the recess has a varying radius.

6. The vehicle electric drive unit component according to claim 5, wherein the recess defines a part teardrop-shape or lachrymiform shape, in crosssection.

7. The vehicle electric drive unit component according to any of claims claim 4 to 6, wherein the recess defines an arc of a circle in cross-section, the circle having a radius of at least 0.4 mm; optionally, at least 0.5 mm; optionally, at least 0.6 mm; optionally, at least 0.75 mm.

8. The vehicle electric drive unit component according to any preceding claim, wherein the vehicle electric drive unit component is formed of metallic material, optionally steel or aluminium alloy material.

9. The vehicle electric drive unit component according to any preceding claim, wherein the first surface and the second surface define a substantially perpendicular angle therebetween.

10. An assembly for an electric drive unit of a vehicle, the assembly comprising:the vehicle electric drive unit component according to any preceding claim; anda different vehicle electric drive unit component comprising at least one bayonet receiver for receiving a respective bayonet connector of the vehicle electric drive unit component such that the vehicle electric drive unit component is securable to the different vehicle electric drive unit component.

11. The assembly according to claim 10, wherein the vehicle electric drive unit component comprises a plurality of bayonet connectors, and wherein the different vehicle electric drive unit component comprises a corresponding plurality of bayonet receivers; optionally, wherein the vehicle electric drive unit component comprises at least three, optionally at least four, optionally at least five, optionally at least six bayonet connectors and wherein the different vehicle electric drive unit component comprises a corresponding number of bayonet receivers.

12. The assembly of claim 10 or claim 11, wherein the different vehicle electric drive unit component is a stator core for an electrical machine of a vehicle traction motor, the stator core comprising a first end, and wherein the vehicle electric drive unit component is a cover which at least partly covers the first end of the stator core.

13. The assembly of claim 12, wherein the stator core comprises a plurality of cooling passageways which extend in a longitudinal direction through the stator core away from the first end, and wherein the cover is a cooling manifold which defines at least one cooling channel in fluid communication with the cooling passageways.

14. An electric machine for driving one or more wheels of a vehicle, the electric machine comprising the assembly of claim 12 or claim 13.5 15. A vehicle comprising the electric machine of claim 14.17

Images