Cooling fluid manifold

Abstract

A cooling fluid manifold 30A for a stator core of an electric machine of a vehicle traction motor. The manifold comprises: an annular body 46 that defines a longitudinal axis, a fixing arrangement 50

Description

TECHNICAL FIELD The present disclosure relates to a cooling fluid manifold for a stator core of an electrical machine of a vehicle traction motor. Aspects of the invention relate to a cooling fluid manifold, to a stator assembly, to an electric machine and to a vehicle. BACKGROUND It is known to provide 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 may be 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. 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 cooling fluid manifold, a stator assembly, an electric machine, and a vehicle as claimed in the appended claims. According to an aspect of the invention, there is provided a cooling fluid manifold for a stator core, the manifold comprising: an annular body that defines a longitudinal axis; a fixing arrangement for securing the manifold to the stator core; a recess extending circumferentially about a first axial side of the annular body, the recess configured to define a chamber; and a reinforcing arrangement configured to provide reinforcement to the annular body. Optionally, the cooling fluid manifold is for a stator core of an electric machine of a vehicle traction motor. Optionally, the reinforcing arrangement comprises a region of increased thickness of the annular body. The reinforcement arrangement has been found to improve the strength and rigidity of the manifold, thereby improving mechanical performance of the manifold, and reducing the likelihood that the manifold will deform in response to elevated temperatures and / or pressures. This is particularly important when using the cooling fluid manifold with a stator core of an electric machine of a vehicle traction motor, where high temperatures may typically cause deformation of materials. Reducing the likelihood of deformation of the annular body reduces the risk of fluid leaks occurring between the cooling fluid manifold and the stator core when the manifold is in use. In this way, fluid communication between the manifold and the stator core is maintained, facilitating effective cooling of the stator core, and reducing the risk of equipment downtime and increased maintenance requirements. It should be understood that the “thickness direction of the annular body refers to the width of the annular body in the axial direction (i.e. in a direction parallel to the longitudinal axis). Optionally, the recess is configured such that the chamber is in fluid communication with the stator core when the manifold is secured to the stator core. Advantageously, the cooling fluid manifold can provide effective cooling to the stator core. Optionally, the reinforcing arrangement comprises at least one reinforcing rib on the first axial side of the annular body. Advantageously, the provision of a reinforcing rib on the annular body has been found to improve the strength and stiffness of the manifold. Optionally, the fixing arrangement comprises a plurality of fixture points arranged circumferentially spaced apart about the annular body, and the at least one reinforcing rib is located between circumferentially adjacent fixture points. Advantageously, the annular body has been found to be particularly susceptible to deformation between adjacent fixture points. In this way, locating reinforcing ribs between adjacent fixture points provides additional strength and stiffness to such a region of the annular body. Optionally, the reinforcing arrangement comprises a plurality of reinforcing ribs arranged circumferentially spaced apart on the first axial side of the annular body. Advantageously, a plurality of reinforcing ribs circumferentially spaced apart facilitates an improved distribution of the reinforcing arrangement, increasing the stiffness and robustness of the manifold about the entire annular body. Optionally, the or each reinforcing rib extends longitudinally from the first axial side of the annular body. Optionally, the or each reinforcing rib extends longitudinally from the first axial side of the annular body so as to abut the stator core when the manifold is secured to the stator core. Advantageously, the reinforcing rib can extend to its maximum longitudinal extent within the designated space confines of a stator assembly, providing effective reinforcement to the annular body. Moreover, the reinforcing ribs can assist in the correct positioning of the manifold relative to the stator core (i.e. in an axial direction). Optionally, the fixing arrangement comprises a plurality of fixing apertures extending longitudinally through the annular body and arranged circumferentially spaced apart about the annular body. Such a fixing arrangement provides a simple means of securing the manifold to a stator core. Further, the provision of a plurality of fixing apertures distributed about the annular body increases the robustness of the connection between the manifold and a stator core. In addition, once connected, such an arrangement can withstand greater axial separation forces than alternative fixing arrangements, such as snap-fit arrangements. Optionally, said fixing apertures are configured for receiving an attachment member to secure the cooling fluid manifold to the stator core. Optionally, the fixing arrangement comprises a plurality of mounting bosses arranged circumferentially spaced apart about the first axial side of the annular body, each fixing aperture extends longitudinally through a respective mounting boss, and wherein the plurality of mounting bosses extend longitudinally from the first axial side of the annular body. Advantageously, the mounting bosses serve to provide additional reinforcement to the manifold while facilitating a robust point for connection between the annular body and stator core. Optionally, wherein the mounting bosses extend so as to abut the stator core when the manifold is secured to the stator core. Optionally, the or each reinforcing rib longitudinally aligns with the plurality of mounting bosses, such that the or each reinforcing rib and the plurality of mounting bosses abut the stator core, in use. Advantageously, the reinforcing ribs and the mounting bosses can extend to their maximum longitudinal extent within the designated space confines of a stator assembly in use, providing effective reinforcement to the annular body. Moreover, axially aligning the reinforcing ribs and mounting bosses can assist in the correct positioning of the manifold relative to the stator core (i.e. in an axial direction). Optionally, the recess is an annular recess so as to define an annular chamber. Advantageously, the manifold allows for fluid flow around the entire circumference of the annular body, increasing the supply of fluid to a stator core, in use. In this way, more effective cooling can be applied to the stator core. Optionally, wherein the annular recess is in fluid communication with the stator core when the manifold is secured to the stator core. Optionally, the recess is a first recess and the cooling fluid manifold further comprises a second recess extending circumferentially about the first axial side of the annular body, the second recess configured to receive a first seal. Advantageously, the manifold can be effectively sealed relative to the stator core in use, preventing leaks of fluid from the electric machine in high-pressure and / or high-temperature situations. Optionally, wherein the first seal is for sealing between the annular body and the stator core when the manifold is secured to the stator core. Optionally, the second recess is an annular recess configured to receive an annular first seal, in use, for sealing between the annular body and the stator core. Advantageously, the manifold is configured to receive an annular seal on an axial side, allowing for effective sealing of the axial side of the annular body along the entire circumference thereof. In this way, the effectiveness of the seal is improved. Optionally, the recess is a first recess and wherein the cooling fluid manifold further comprises a third recess extending circumferentially about a radially outer surface of the annular body, the third recess configured to receive a second seal. Advantageously, the manifold can be effectively sealed relative to a housing of the electric machine in use, preventing leaks of fluid from the electric machine in high-pressure and / or high-temperature situations. Optionally, the second seal is for sealing between the annular body and a housing of the electric machine when the manifold is secured to the stator core. Optionally, the third recess is an annular recess configured to receive an annular second seal, in use, for sealing between the annular body and a housing of the electric machine. Advantageously, the manifold is configured to receive an annular seal on a radial surface, allowing for effective sealing of the outer radial surface of the annular body along the entire circumference thereof. In this way, the effectiveness of the seal is improved. Optionally, the annular body is formed of metallic material, optionally steel or aluminium alloy material. This provides a robust manifold. Optionally, the reinforcing arrangement comprises at least one reinforcing rib located within the recess. Advantageously, the recess may be a region susceptible to deformation. As such, locating the reinforcing arrangement therein can improve the strength and robustness of such a region. Optionally, the reinforcing arrangement comprises one or more reinforcing ribs arranged to extend circumferentially within the recess. Advantageously, reinforcement is provided by the ribs around the annular body. Optionally, the recess is an annular recess, and the reinforcing arrangement comprises an annular reinforcing rib arranged to extend circumferentially within the recess. Advantageously, the reinforcing rib may extend continuously about the recess. In this way, reinforcement is provided about the entire circumference of the recess. Optionally, the reinforcing arrangement comprises one or more reinforcing ribs arranged to extend radially within the recess. Advantageously, the radially extending reinforcing ribs provide additional support to the recess, reducing the risk of deformation thereof. Optionally, the reinforcing arrangement comprises a circumferentially extending reinforcing rib arranged to extend circumferentially within the recess, and a plurality of radially extending reinforcing ribs arranged circumferentially spaced apart within the recess. Advantageously, the provision of reinforcing ribs extending in multiple directions provides additional support to the recess and to the annular body. Optionally, the recess defines a recess height in an axial direction and the one or more reinforcing ribs defines a rib height in an axial direction, the recess height is greater than the rib height. Advantageously, the one or more reinforcing ribs do not occupy the entirety of the recess in an axial direction and so do not significantly reduce or block a flow path defined by the recess, in use. In this way, the reinforcing ribs can provide reinforcement without significantly reducing the volumetric capacity of the manifold. Optionally, the or each reinforcing rib extends longitudinally from the annular body so as to be spaced apart from the stator core, in use. Advantageously, the reinforcing ribs do not obstruct the flow of fluid in the chamber defined by the manifold, facilitating effective cooling of the stator core in use. Optionally, the one or more reinforcing ribs are formed of a metal material, optionally steel or aluminium alloy material. Optionally, the one or more reinforcing ribs are formed of a plastic material. Optionally, the reinforcing arrangement comprises a reinforcing insert. Advantageously, a reinforcing insert can provide additional support to the annular body and reduce the risk of deformation. Optionally, the reinforcing insert is secured to a second axial side of the annular body, opposite to the first axial side. Advantageously, the reinforcing insert can provide effective support without occupying space on the first axial surface of the annular body, which includes one or more recesses. Optionally, the reinforcing insert is positioned within the recess. Advantageously, the recess may be a region susceptible to deformation. As such, locating the insert therein can improve the strength and robustness of such a region. Optionally, the fixing arrangement comprises a plurality of fixture points arranged spaced apart circumferentially about the annular body, and wherein the reinforcing insert is positioned within the recess between circumferentially adjacent fixture points. Advantageously, the annular body has been found to be particularly susceptible to deformation between adjacent fixture points. In this way, locating a reinforcing insert between adjacent fixture points provides additional strength and stiffness to such a region of the annular body. Optionally, the reinforcing insert is a metal insert; optionally, a steel insert. This provides robust support to the manifold. Optionally, the annular body is formed of plastic material. Advantageously, the annular body is simple to manufacture. Optionally, the fixing arrangement comprises a bayonet arrangement. Such a bayonet arrangement provides a simple means of securing a manifold to an end of a stator core (e.g., by pushing and twisting the cover and stator core 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 fixing arrangement comprises one or more resilient clips configured to engage with a corresponding one or more receiving recesses of the stator core. Such an arrangement provides a secure connection. Optionally, the fixing arrangement comprises a plurality of axially extending flanges circumferentially spaced apart about the annular body, said flanges each comprises a fixing aperture extending radially therethrough for receiving an attachment member to secure the manifold to the stator core. Such an arrangement facilitates a radially extending attachment member for fixing the manifold to the stator core, providing a robust connection between the two components. A further aspect of the present disclosure provides a stator assembly for an electric machine of a vehicle traction motor, the stator assembly comprising the stator core and the cooling fluid manifold as disclosed herein. Such a stator assembly benefits from the advantages of the cooling fluid manifold outlined above. Optionally, the stator core comprises a plurality of fluid passageways extending therethrough in a longitudinal direction away from an axial end of the stator core, and the cooling fluid manifold is positioned against the axial end of the stator core so that the recess defines a chamber in fluid communication with the cooling passageways. Advantageously, the stator assembly can be effectively cooled via the cooling passageways. A further aspect of the present disclosure provides an electric machine for driving one or more wheels of a vehicle, the electric machine comprising the cooling fluid manifold as disclosed herein and / or the stator assembly as disclosed herein. Optionally, the electric machine further comprises a cooling fluid recirculation circuit configured to supply cooling fluid to the cooling fluid manifold. 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 stator assembly outlined above. A further aspect of the present disclosure provides a method of coupling a cover to a stator core (e.g., of an electric machine for a vehicle traction motor). The method comprises: a) providing a stator core comprising an axial end surface; b) positioning a cover against the axial end surface of the stator core; and c) securing the cover to the stator core using a fixing arrangement. Optionally, the cover is a cooling fluid manifold as disclosed herein. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in anyway 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 transverse cross-sectional view of the electrical machine of Figure 2; Figure 4 shows a plan view of a cooling fluid manifold according to an embodiment; Figure 5 shows a perspective view of the cooling fluid manifold of Figure 4; Figure 6 shows a perspective, cross-sectional view of a portion of the cooling fluid manifold of Figure 4; Figures 7A and 7B show perspective front views of a section of a cooling fluid manifold according to embodiments; Figures 8A and 8B show perspective front views of a section of a cooling fluid manifold according to embodiments; Figures 9A, 9B and 9C show perspective rearviews of a section of a cooling fluid manifold according to embodiments; and Figure 10 shows a method of coupling a coverto a stator core. DETAILED DESCRIPTION Examples of the present disclosure relate to a cooling fluid manifold stator assembly. In particular, examples of the present invention relate to a cooling fluid manifold for a stator core of 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, a cooling fluid manifold 30A, 30B, an electric machine 100, an electric drive unit (EDU) 160, a vehicle 200 and a method. Figure 1 illustrates a vehicle 200 having a first electric machine 100-1 which is part of a vehicle traction motor fordriving 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 fordriving 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 Figures 2 and 3, 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 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 159. For simplicity, the electrical stator windings 150 are illustrated in Figure 3 in only one winding slot 22. A plurality of stator teeth 24 are provided between the winding slots 22. In other words, the stator teeth 24 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 24 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 may be utilised. As shown in Figures 2 and 3, 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 fluid manifold. As will be discussed in more detail, the first cooling fluid manifold 30A defines at least one recess 32A in fluid communication with the plurality of cooling passageways 28. In the illustrated embodiment, the at least one recess 32A defines a first chamber 32A in fluid communication with the plurality of cooling passageways 28. The first cooling fluid 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 fluid 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 cover30B is a second cooling fluid manifold. The second cooling fluid manifold 30B defines at least one recess 32B in fluid communication with the plurality of cooling passageways 28. In the illustrated embodiment, the at least one recess 32B defines a second chamber 32B in fluid communication with the plurality of cooling passageways 28. The second cooling fluid 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 fluid 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 fluid 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 fluid manifold 30A, along the cooling passageways 28, into the second cooling fluid 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 fluid manifold 30B, along the cooling passageways 28, into the first cooling fluid 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 fluid manifold 30A would instead be a manifold outlet, and similarly the manifold outlet 34B of the second cooling fluid manifold 30B would instead be a manifold inlet. In the illustrated arrangement, the first and second cooling fluid manifolds 30A, 30B are annular. Correspondingly, the first and second chambers 32A, 32B are also annular. The first and second cooling fluid 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 fluid manifold 30A faces the first axial end surface 18 of the stator core 12 and a second side of the first cooling fluid manifold faces the first axial end surface 102A of the housing 102. Similarly, a first side of the second cooling fluid manifold 30B faces the second axial end surface 20 of the stator core 12, and a second side of the second cooling fluid manifold 30B faces the second axial end surface 102B of the housing 102. In the illustrated arrangement, the second side of the second cooling fluid manifold 30B is provided adjacent to the second axial end surface 102B ofthe housing 102. On the contrary, although the second side of the first cooling fluid manifold 30A faces the first axial end surface 102A ofthe housing 102, the first cooling fluid manifold 30A is not provided adjacent to the first axial end surface 102A ofthe housing 102. In other words, the first cooling fluid manifold 30A is spaced apart from the first axial end surface 102A ofthe housing 102 in an axial direction. In addition, at least one further component 114 ofthe electric machine 100 is positioned axially between the second side ofthe first cooling fluid manifold 30A and the first axial end surface 102A of the housing 102 (as illustrated schematically on Figure 2). It will be appreciated that in alternative arrangements, the further component 114 may not be present and / or the first cooling fluid manifold 30A may be provided adjacent the first axial end surface 102A ofthe housing 102. 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 ofthe first cooling fluid manifold 30A in a cooling fluid recirculation circuit 122 (i.e., via the first opening 104 in the housing 102). In the illustrated arrangement, 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 with a plastic material to provide sealing such that cooling fluid is prevented, or resisted, from passing between the laminations (i.e. layers 44A, 44E3, 44C) 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 a 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 innersurface of the cooling passageways 28 is in the region of 0.5 mm, 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. Referring now to Figures 4 to 6, the first cooling fluid manifold 30A of Figures 2 and 3 will be described in more detail. It will be appreciated that the features described in relation to the first cooling fluid manifold 30A may also form the second cooling fluid manifold 30B in some arrangements. In some arrangements, only the first cooling fluid manifold 30A may be present in the stator assembly 10. The cooling fluid manifold 30A includes an annular body 46 that defines a longitudinal axis L. The longitudinal axis L of the annular body 46 may be coaxial with the central stator axis 16 when the cooling fluid manifold 30A is secured to the stator core 12. The annular body 46 may be formed of metallic material, for example steel or aluminium alloy material. In alternative arrangements, the annular body 46 is formed of plastic material. The cooling fluid manifold 30A also includes a fixing arrangement 50 which is configured to secure the cooling fluid manifold 30A to the stator core 12. Such a fixing arrangement 50 provides a simple means of securing the manifold 30A relative to the stator core 12. 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), a suitably robust connection between the first cooling fluid manifold 30A and the stator core 12 can be provided without complication. The fixing arrangement 50 may include one or more fixture points for secunng the manifold 30A to the stator core 12. In some arrangements, a plurality of fixture points may be arranged circumferentially spaced apart about the annular body 46. As will be discussed in more detail below, the fixture points may include any suitable fixture interface. In the arrangement of Figures 3 to 6, the fixing arrangement 50 includes at least one fixing aperture 48 that extends longitudinally through the annular body 46. In the arrangement of Figures 4 to 6, the fixing arrangement 50 includes a plurality of fixing apertures 48 arranged circumferentially spaced apart about the annular body 46. The fixing apertures 48 are configured to receiving an attachment member (not shown), e.g. a bolt, to secure the cooling fluid manifold 30A to the stator core 12. The fixing apertures 48 are configured for receiving an attachment member in a generally longitudinal direction. As is best seen in Figure 4, the fixing apertures 48 are distributed evenly or equidistantly about the annular body 46 of the manifold 30A. In the figures, six fixing apertures 48 are provided. The fixing apertures 48 are evenly spaced around the annular body 46 so as to define an interval of 60 degrees relative to the longitudinal axis L. It will be appreciated that any number of fixing apertures 48 may be provided. The fixing apertures 48 may not be evenly distributed in some arrangements. While the fixing apertures 48 of Figures 4 to 6 are radially aligned on the annular body 46, the fixing apertures 48 may occupy different radial positions on the annular body 46 in some arrangements. The fixing arrangement 50 includes at least one mounting boss 52 that extends longitudinally from a first axial side 46A of the annular body 46. In the figures, each fixing aperture 48 extends longitudinally through a respective mounting boss 52 and through the annular body 46. In this way, a plurality of mounting bosses 52 are provided (i.e. one per fixing aperture 48), arranged circumferentially spaced apart about the first axial side 46A of the annular body 46. In the figures, six mounting bosses 52 are provided. The mounting bosses 52 may extend from the first axial side 46A of the annular body 46 so as to abut the stator core 12 (e.g. to abut an axial end surface 18 of the stator core 12) when the manifold 30A is secured to the stator core 12. The mounting bosses 52 can provide for a robust point of connection between the annular body 46 and the stator core 12. The mounting bosses may not be present in some arrangements, and the fixing apertures 48 may extend directly through the annular body 46. As is best seen in Figure 6, a curved interface 57 may be provided between the mounting boss 52 and the first axial side 46A of the annular body 46 to define a smooth transition between a respective mounting boss 52 and the annular body 46. This reduces an accumulation of stress that may be generated between the mounting boss 52 and the body 46 compared with a sharp transition, as the smooth corner mitigates potential pressure points or stress concentrations between the components. In the illustrated arrangement, the mounting boss 52 defines a generally cuboidal shape with the aperture 48 extending therethrough. It will be appreciated that the mounting boss 52 may be any suitable shape. The mounting boss 52 may include a generally planar abutment surface through which the aperture 48 extends, such that the interface between the mounting boss 52 and the respective surface of the stator core 12 is generally planar. The one or more mounting bosses 52 may be positioned so as to not obstruct cooling fluid in the first chamber 32A. The mounting bosses 52 may be located on the annular body 46 in a radially outboard position relative to the first recess 32A. In the arrangement of Figures 3 to 6, a portion of the mounting boss 52 extends into the recess 32A. This arrangement may provide some reinforcement to the recess 32A, without completely obstructing cooling fluid in the first chamber 32A when the manifold 30A is secured to the stator core 12. The mounting bosses 52 may be formed from any suitable material. The mounting bosses 52 may be formed from the same material as the annular body 46, e.g. so as to be integrally formed therewith. The mounting bosses 52 may be formed of metallic material, for example steel or aluminium alloy material. In alternative arrangements, the mounting bosses 52 are formed of plastic material. As noted above, the first cooling fluid manifold 30A defines a recess 32A. The recess 32A extends circumferentially about the first axial side 46A of the annular body 46. As discussed above, the recess 32A is configured to define a chamber 32A. The recess 32A is configured such that the chamber 32A is in fluid communication with the stator core 12 when the first cooling manifold 30Ais secured to the stator core 12 (e.g. via the fixing arrangement 50). In the figures, the recess 32A is an annular recess such that the chamber 32A is an annular chamber. In this way, fluid can flow around the entire circumference of the annular body 46, increasing the distribution of fluid in the stator core 12. The recess 32A is continuous so as to define a closed loop about the first axial side 46A of the annular body 46. In the figures, it can be seen that the recess 32A is a first recess 32A. The cooling fluid manifold 30A includes a second recess 42A. The second recess 42A extends circumferentially about the first axial side 46A of the annular body 46 and is configured to receive a first seal 40A. The first seal 40A seals between the annular body 46 and the stator core 12 when the manifold 30A is secured to the stator core 12. The second recess 42A is an annular recess in the figures. The second recess 42A extends continuously so as to define a closed loop on the first axial side 46A of the annular body 46. The second recess 42A is located radially inwardly relative to the first recess 32A, although it will be appreciated that the second recess 42A may be arranged radially outwardly in other arrangements. In the figures, a single wall 53 separates the first recess 32A from the second recess 42A. Put another way, a wall 53 defines the radially outer edge of the second recess 42A and the radially inner edge of the first recess 32A. In the arrangement of Figure 2, the first seal 40A is a first axial seal 40A located between the first end 18 of the stator core 12 and the first cooling manifold 30A. In particular, the first axial seal 40A is an annular seal. The second recess 42A locates the first seal 40A in the correct position. As is best seen in Figure 6, the cooling fluid manifold 30A includes a third recess 43 extending circumferentially about a radially outer surface 46B of the annular body 46. The third recess 43 is configured to receive a second seal 41. The third recess 43 is an annular recess. The third recess 43 extends continuously so as to define a closed loop on the radially outer surface 46B of the annular body 46. The second seal 41 seals between the annular body 46 and the housing 102 of the electric machine 100 when the manifold 30A is secured to the stator core 12. In the arrangement of Figure 2, the second seal 41 is a radial seal 41 that is located between the radially outer surface 46B of the first cooling fluid manifold 30A and a radial inner surface of the housing 102. In particular, the second seal 41 is an annular seal (e.g., an O-ring). The second seal 41 is located in the third recess 43, which locates the radial seal 41 in the correct position. A further axial seal 40B may be located between the second end 20 of the stator core 12 and the second cooling manifold 30B to seal the second chamber 32B. In particular, the axial seal 40B is an annular seal. The 13 axial seal 40B is located in an annular recess 42B in the second cooling manifold 30B, which locates the axial seal 40B in the correct position. Similarly, another axial seal 40C is provided at an opposite side of the second cooling manifold 30B to the axial seal 40B. The axial seal 40C is configured to form a seal between the second cooling manifold 30B and an axial end of the housing 102. The axial seal 40C is located in a further annular recess 42C in the second cooling manifold 30B, which locates the third axial seal 40C 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. It will be appreciated that the cooling fluid manifold 30A may be exposed to high pressures (e.g. from the cooling fluid) passing therethrough and / or high temperatures (e.g. from the stator core 12 and / or other components of the electric machine 100). As such, the cooling fluid manifold 30A is susceptible to stress and deformation. Reducing the likelihood and extent of deformation of the cooling fluid manifold 30A is important in maintaining effective cooling of the stator core 12, preventing leaks of cooling fluid and reducing equipment downtime. As such, the cooling fluid manifold 30A includes a reinforcing arrangement 54 configured to provide reinforcement to the annular body 46. The reinforcing arrangement 54 includes a region of increased thickness of the annular body 46. It should be understood that the “thickness” direction of the annular body 46 refers to a width of the annular body 46 in an axial direction (i.e. in a direction parallel to the longitudinal axis). In the arrangement of Figures 4 to 6, the reinforcing arrangement includes at least one reinforcing rib 56A on the first axial side 46A of the annular body 46. The reinforcing rib 56A is configured to improve the strength and stiffness of the cooling fluid manifold 30A, e.g. by increasing the thickness of the annular body 46. The at least one reinforcing rib 56A extends longitudinally from the first axial side 46A of the annular body 46 in the figures. In alternative arrangements, the reinforcing arrangement 54 may include one or more reinforcing ribs 56A extending from other surfaces of the annular body 46, e.g. the outer radial surface 46B or a second axial surface 46C of the annular body 46. The or each reinforcing rib 56A may extend from the first axial side 46A of the annular body 46 so as to abut the stator core 12 (e.g. to abut an axial end surface 18 of the stator core 12) when the manifold 30A is secured to the stator core 12. In this way, the or each reinforcing rib 56A may be axially aligned with the one or more mounting bosses 52 such that the reinforcing rib 56A and the mounting bosses 52 abut the stator core 12. The or each reinforcing rib 56A may include a generally planar abutment surface, such that the interface between the reinforcing rib 56A and the respective surface of the stator core 12 is generally planar when the manifold 30A is secured to the stator core 12. The reinforcing ribs 56A and / or the mounting bosses 52 are configured to extend to their respective maximum longitudinal extent within the designated space confines of a stator assembly 12 in use, providing effective reinforcement to the annular body 46. Axially aligning the or each reinforcing ribs 56A and mounting bosses 52 can assist in the correct positioning of the manifold 30A relative to the stator core 12 (i.e. in an axial direction). As is best seen in Figure 6, a curved interface 55 may be provided between the reinforcing rib 56A and the first axial side 46A of the annular body 46 to define a smooth transition between the respective reinforcing rib 14 56A and the annular body 46. This reduces an accumulation of stress that may be generated between the rib 56A and the body 46 compared with a sharp transition, as the smooth corner mitigates potential pressure points or stress concentrations between the components. In the illustrated arrangement, the reinforcing rib 56A defines a generally cuboidal shape. It will be appreciated that the reinforcing rib 56A may be any suitable shape. It will be appreciated that the annular body 46 may be particularly susceptible to deformation between adjacent fixture points (e.g. between adjacent fixing apertures 48 in the figures). In orderto compensate for an increased risk of deformation, one or more reinforcing ribs 56A may be located between circumferentially adjacent fixture points. The reinforcing rib 56A may be positioned equidistantly between two circumferentially adjacent fixture points. In some arrangements, more than one reinforcing rib 56A may be provided between circumferentially adjacent fixture points. In alternative arrangements, reinforcing ribs 56A may only be provided between some circumferentially adjacent fixture points and not others. In the figures, a plurality of reinforcing ribs 56A are provided. The reinforcing ribs 56A are arranged circumferentially spaced apart on the first axial side 46A of the annular body. The plurality of reinforcing ribs 56A may be distributed equidistantly about the annular body 46. The plurality of reinforcing ribs 56A are configured to provide a distribution of the reinforcing effect, improving the stiffness and robustness of the cooling fluid manifold 30A about the circumference of the annular body 46. At least one reinforcing rib 56A is positioned or interposed between two circumferentially adjacent fixing apertures 48. In the arrangement of Figure 4, one reinforcing rib 56A is provided between adjacent fixing apertures 48. In this arrangement, one reinforcing rib 56A is provided for every fixing aperture 48. For example, in the figures, six fixing apertures 48 are provided and so six reinforcing ribs 56A are provided. It will be appreciated that any number of reinforcing ribs 56A may be provided (e.g. more than or less than one per fixing aperture 48). The reinforcing ribs 56A and fixing apertures 48 are alternately arranged circumferentially about the first axial side 46A of the annular body 46. In the illustrated arrangement, the alternating reinforcing ribs 56A and fixing apertures 48 are equally spaced apart from one another. In this way, the fixing apertures 48 and the reinforcing ribs 56A are evenly spaced around the annular body 46 so as to define an interval of 30 degrees between adjacent components relative to the longitudinal axis L. It will be appreciated that any number of reinforcing ribs 56A may be provided. Although the plurality of reinforcing ribs 56A are substantially identical to each other in the figures, it will be appreciated that the reinforcing ribs 56A may be configured differently from one another in other arrangements, e.g. the reinforcing ribs 56A may have different shapes, may extend from the annular body 46 by different extents, may have a different transition between the annular body 46 and the rib 56A and the like. The one or more reinforcing ribs 56A may be positioned so as to not obstruct cooling fluid in the first chamber 32A or the space available for the first seal 40A in the second recess 42A. In the illustrated arrangement, the reinforcing ribs 56A are positioned on the annular body 46 in a radially outboard position relative to the first recess 32A. The reinforcing ribs 56A may be formed from any suitable material. The reinforcing ribs 56A may be formed from the same material as the annular body 46, e.g. so as to be integrally formed therewith. The reinforcing ribs 56A and the mounting bosses 52 may be formed from the same material in some arrangements. The 15 reinforcing ribs 56A may be formed of metallic material, for example steel or aluminium alloy material. In alternative arrangements, the reinforcing ribs 56A are formed of plastic material. The reinforcing ribs 56A have been found to provide particularly effective reinforcement when the annular body is formed of metallic material. Alternative reinforcing arrangements 54 of the cooling fluid manifold 30A will now be discussed with reference to Figures 7A to 9C. Only the differences between these arrangements and that previously described will be discussed in detail. It will be understood that the reinforcing arrangements 54 described herein may be implemented in any combination with each other. Referring firstly to Figures 7A and 7E3, the reinforcing arrangement 54 includes at least one reinforcing rib located within the first recess 32A. As will be understood, the first recess 32A may be a region susceptible to deformation. As such, locating the reinforcing arrangement 54 therein can improve the strength and robustness of such a region. In Figures 7A and 7B, the reinforcing arrangement 54 includes a circumferential reinforcing rib 56B arranged to extend circumferentially within the first recess 32A. The circumferential reinforcing rib 56B is annular. The circumferential reinforcing rib 56B may have an elongate body. The rib 56B may extend continuously about the circumference of the first recess 32A. The reinforcing arrangement 54 includes at least one radial reinforcing rib 56C arranged to extend radially within the first recess 32A. In the figures, a plurality of radial reinforcing ribs 56C are provided, circumferentially spaced apart about the first recess 32A. In the arrangement of Figure 7A, the radial reinforcing ribs 56C are evenly distributed about the first recess 32A, e.g. each rib 56C is equidistant from the adjacent ribs 56C. The radial reinforcing ribs 56C of Figure 7B may be arranged with variable circumferential differences therebetween. As can be seen in Figure 7B, the radial reinforcing ribs 56C are here closer together in the region of the fixing arrangement 50, and are more spaced apart elsewhere on the manifold 30A. In this way, additional support can be provided in the region of the fixing arrangement 50. It will be appreciated that any spacing of radial reinforcing ribs 56C may be implemented. The or each radial reinforcing rib 56C may extend across the entire radial extent of the first recess 32A, e.g. between two opposing radial edges. The or each radial reinforcing rib 56C may intersect the circumferential reinforcing rib 56B so as to define a substantially perpendicular angle therebetween. In some arrangements, only one of the circumferential reinforcing rib 56B and the one or more radial reinforcing ribs 56C are provided. The or each reinforcing rib 56B and / or 56C defines a longitudinal projection extending from the annular body 46 so as to provide a region of increased thickness of the annular body 46. In some arrangements, the circumferential reinforcing rib 56B and / or the one or more radial reinforcing ribs 56C may be provided external of the recess 32A, e.g. radially outboard thereof on the annular body 46. The one or more reinforcing ribs 56B, 56C may be dimensioned so as to not obstruct cooling fluid in the first chamber 32A. In the illustrated arrangement, the reinforcing ribs 56B, 56C define a rib height in the axial direction that is less than a height of the recess 32A in the axial direction (e.g. the recess height). In this way, the one or more reinforcing ribs 56B, 56C do not occupy the entirety of the recess in an axial direction and so do not significantly reduce or block a flow path defined by the recess 32A, in use. In this way, the or each 16 reinforcing rib 56B, 56C can provide reinforcement without significantly reducing the volumetric capacity of the manifold 30A.Put another way, the or each reinforcing rib 56B, 56C may extend longitudinally from the first axial surface 46A of the annular body 46 so as to be spaced apart from the stator core 12, when the cooling fluid manifold 30A is secured to the stator core 12. The one or more reinforcing ribs 56B, 56C may be formed from any suitable material. The reinforcing ribs 56B, 56C may be formed from the same material as the annular body 46, e.g. so as to be integrally formed therewith. The reinforcing ribs 56B, 56C may be formed of metallic material, for example steel or aluminium alloy material. In alternative arrangements, the reinforcing ribs 56B, 56C are formed of plastic material. The reinforcing ribs 56B, 56C have been found to provide particularly effective reinforcement when the annular body is formed of plastic material. In the arrangement of Figures 7A and 7B, the fixing arrangement 50 differs from that described above with respect to Figures 4 to 6 and includes at least one axially extending flange 60. In some arrangements, a plurality of axially extending flanges 60 are provided circumferentially spaced apart about the annular body 46. The flanges 60 may extend in a direction toward the stator core 12 so as to overlay an outer radial surface of the stator core 12 when the manifold 30A is secured thereto. The flanges 60 may include a fixing aperture 62 extending radially therethrough. The fixing aperture 62 may be configured for receiving an attachment member (e.g. a bolt or a pin) to secure the cooling fluid manifold 30A to the stator core 12. The attachment member may extend in a generally radial direction to secure the manifold 30A to the stator core 12. It will be appreciated that any number of flanges 60 may be provided, distributed about the annular body 46. (Circumferential recesses (not shown) will be in the cylindrical surface of the stator to receive the flanges 60.) In the arrangement of Figures 8A, 8B, 9A, 9B and 9C, the reinforcing arrangement 54 includes a reinforcing insert 64. The reinforcing insert 64 is configured to provide support to the annular body 46 so as to reduce the risk of deformation. The reinforcing insert 64 may be shaped to compliment the annular body 46, e.g. so as to abut against a respective surface of the annular body 46. In Figures 8A and 8B, the reinforcing arrangement 54 includes at least one reinforcing insert 64 located within the first recess 32A. The reinforcing insert 64 is arranged to abut against an axially inner surface of the first recess 32A. The reinforcing insert 64 may be arranged to at least partially abut against a radial edge of the first recess 32A, e.g. so as to provide some reinforcement to the edges that define the recess 32A. In Figure 8A, the reinforcing insert 64 is dimensioned to extend circumferentially about a region of the first recess 32A. In some arrangements, the reinforcing insert 64 may extend circumferentially about the entire first recess 32A as partially shown in Figure 8B (e.g. about the entire circumferential extent of the axial surface defined by the recess 32A). In Figure 8A, the reinforcing insert 64 defines a partial annular shape so as to extend about only a region of the first recess 32A. In Figure 8B, the reinforcing insert defines an annular shape so as to extend about the entire circumference of the first recess 32A. Alternatively, multiple reinforcing inserts 64 may be provided, circumferentially spaced apart from one other within the recess 32A. In some arrangements, a reinforcing insert 64 may be provided between circumferentially adjacent fixing arrangements 50, so as to improve the rigidity of the recess in between adjacent fixing arrangements 50. In some arrangements (e.g. as best seen in Figure 8A), the respective reinforcing insert 64 may be arranged such that 17 a circumferentially centre point of an insert 64 is aligned with the central point of a respective fixing arrangement 50. The or each reinforcing insert 64 may be secured within the recess 32A by any suitable means, e.g. a bolting arrangement, clamping, adhesive, welding, brazing, or the like. In some arrangements, the reinforcing insert 64 may be dimensioned to locate in an interference fit with the recess 32A. In Figures 9A to 9C, the reinforcing insert 64 is secured to a second axial surface 46C of the annular body 46, opposite to the first axial surface 46A. The reinforcing insert 64 may be secured via any suitable means, including bolting, clamping, adhesive, welding, brazing, or the like. In Figures 9A and 9B, the reinforcing insert 64 is formed as a separate component to the annular body 46. The reinforcing insert 64 of Figure 9C is integrally formed with the annular body 46. The insert 64 of Figure 9C may be embedded inside the annular body 46. Embedding the insert removes the need for a specialised fixing method. The arrangement of Figure 9C is particularly advantageous if the insert is formed from a metallic material and the annular body 46 is formed from a plastic material. The reinforcing insert 64 is configured to increase the thickness of the annular body, provide effective support thereto without occupying space on the first axial surface 46A of the annular body 46 (e.g. allowing for additional space for the recesses 32A, 42A). In this way, the flow path defined by the first chamber 46A is substantially unobstructed. The reinforcing insert 64 may be dimensioned to compliment the second axial surface 46C so as to abut thereagainst. In the illustrated embodiment, the second axial surface 46C is substantially planar and so the reinforcing insert 64 has a substantially planar profile to facilitate abutting the reinforcing insert 64 against the second axial surface 46C. In Figures 9B and 9C, the reinforcing insert 64 defines a substantially annular profile, so as to extend circumferentially about the entire second axial surface 46C (e.g. in the circumferential direction). It will be appreciated that the embedded arrangement of Figure 9C may include one or more partially annular inserts 64 arranged about the annular body 46 in some arrangements. In Figure 9A, the reinforcing insert 64 defines a partially annular profile so as to extend only about a portion of the circumferential extent of the second axial surface 46C. In such an arrangement, multiple reinforcing inserts 64 may be provided that are arranged on the second axial surface 46C so as to be circumferentially spaced apart from one another. The reinforcing inserts 64 may be arranged so as to extend circumferentially between adjacent fixing arrangements 50, so as to provide additional strength and stiffness to the annular body 46 between the fixing arrangements 50. In some arrangements (e.g. where the insert 64 defines a partially annular shape), the respective reinforcing insert 64 may be arranged such that a circumferentially centre point of an insert 64 is aligned with the central point of a respective fixing arrangement 50. The one or more reinforcing inserts 64 described in relation to any of Figures 8A to 9C may be formed from any suitable material. The reinforcing insert 64 is particularly effective when formed of metallic material, for example steel or aluminium alloy material. However, it should be appreciated that the reinforcing insert 64 may be formed from a plastic material in alternative arrangements. The reinforcing insert 64 provides particularly effective reinforcement when the annular body is formed of plastic material. It will be appreciated that the arrangements described herein may include any combination of the above reinforcing arrangements 54, The arrangements may also include any suitable fixing arrangement 50. In one arrangement, the fixing arrangement 50 may include an interlocking arrangement, e.g. a bayonet arrangement (not shown). For example, the bayonet arrangement may include at least one bayonet connector on one of the cooling fluid manifold 30A and the stator core 12 and at least one bayonet receiver on the other of the cooling fluid manifold 30A and the stator core 12. Such a bayonet arrangement 50 provides a simple means of securing the first cooling fluid manifold 30A to the stator core 12 (e.g., by pushing and twisting the first cooling fluid manifold 30A and stator core 12 relative to each other). Other interlocking arrangements may be implemented in alternative arrangements. In another alternative arrangement, the fixing arrangement 50 may include a snap-fit arrangement. Such a snap-fit arrangement allows the cooling fluid manifold 30A to be secured to the stator core 12 simply by pushing the cooling fluid manifold 30A towards the stator core 12. The fixing arrangement 50 may include one or more resilient clips on the cooling fluid manifold 30A configured to engage with a corresponding one or more receiving recesses of the stator core 12. In alternative embodiments, the first cooling fluid manifold 30A may be clamped between the first axial end surface 102A of the housing 102 and the stator core 12 (e.g., the at least one further component 114 may be omitted). In such embodiments, a snap-fit arrangement may be used. It will be appreciated that any combination of the fixing arrangements 50 described may be implemented into the cooling fluid manifold 30A. The second cooling fluid manifold 30B may include one or more of the fixing arrangements 50 discussed in relation to the first cooling fluid manifold 30A. The two manifolds 30A, 30B may include different fixing arrangements. A method of coupling a cover 30A, 30B to a stator core 12 is illustrated in Figure 10 as a flow chart. The method includes the following steps: a) providing a stator core 12 comprising an axial end surface 18, 20; b) positioning a cover 30A, 30B against the axial end surface 18, 20 of the stator core 12; and c) securing the cover 30A, 30B to the stator core 12 using a fixing arrangement 50. 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 cooling fluid manifold for a stator core of an electric machine of a vehicle traction motor, the manifold comprising:an annular body that defines a longitudinal axis;a fixing arrangement for securing the manifold to the stator core;a recess extending circumferentially about a first axial side of the annular body, the recess configured to define a chamber; anda reinforcing arrangement configured to provide reinforcement to the annular body;wherein the reinforcing arrangement comprises a region of increased thickness of the annular body.

2. The cooling fluid manifold according to claim 1, wherein the recess is configured such that the chamber is in fluid communication with the stator core when the manifold is secured to the stator core.

3. The cooling fluid manifold according to claim 1 or claim 2, wherein the reinforcing arrangement comprises at least one reinforcing rib on the first axial side of the annular body.

4. The cooling fluid manifold according to claim 3, wherein the fixing arrangement comprises a plurality of fixture points arranged circumferentially spaced apart about the annular body, and wherein the at least one reinforcing rib is located between circumferentially adjacent fixture points.

5. The cooling fluid manifold according to claim 3 or claim 4, wherein the reinforcing arrangement comprises a plurality of reinforcing ribs arranged circumferentially spaced apart on the first axial side of the annular body.

6. The cooling fluid manifold according to any of claims 3 to 5, wherein the or each reinforcing rib extends longitudinally from the first axial side of the annular body.

7. The cooling fluid manifold according to any preceding claim, wherein the fixing arrangement comprises a plurality of fixing apertures extending longitudinally through the annular body and arranged circumferentially spaced apart about the annular body.

8. The cooling fluid manifold according to claim 7, wherein the fixing arrangement comprises a plurality of mounting bosses arranged circumferentially spaced apart about the first axial side of the annular body, wherein each fixing aperture extends longitudinally through a respective mounting boss, and wherein the plurality of mounting bosses extend longitudinally from the first axial side of the annular body.

9. The cooling fluid manifold according to any preceding claim, wherein the recess is a first recess and wherein the cooling fluid manifold further comprises a second recess extending circumferentially about the first axial side of the annular body, the second recess configured to receive a first seal.

10. The cooling fluid manifold according to any preceding claim, wherein the recess is a first recess and wherein the cooling fluid manifold further comprises a third recess extending circumferentially about a radially outer surface of the annular body, the third recess configured to receive a second seal.

11. The cooling fluid manifold according to any preceding claim, wherein the annular body is formed of metallic material, optionally steel or aluminium alloy material.

12. A stator assembly for an electric machine of a vehicle traction motor, the stator assembly comprising the stator core and the cooling fluid manifold of any preceding claim.

13. The stator assembly of claim 12, wherein the stator core comprises a plurality of fluid passageways extending therethrough in a longitudinal direction away from an axial end of the stator core, and wherein the cooling fluid manifold is positioned against the axial end of the stator core so that the recess defines a chamber 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 cooling fluid manifold of any of claims 1 to 11 and / or the stator assembly of claim 12 or 13; optionally, further comprising a cooling fluid recirculation circuit configured to supply cooling fluid to the cooling fluid manifold.

15. A vehicle comprising the electric machine of claim 14.

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