A stator assembly for an electric motor

Abstract

A stator assembly for an electric motor of a vehicle comprising a stator 20 having a manifold 130 located adjacent a first end 23 of the stator, and a stator housing 11 with a recess 111 within which

Description

TECHNICAL FIELD The present disclosure relates to a stator assembly for an electric motor. Aspects of the invention relate to a stator assembly for an electric motor, to an electric motor, to a method of assembling a stator assembly for an electric motor, and to a vehicle comprising a stator assembly or an electric motor. BACKGROUND It is known to install a stator assembly in a stator housing of an electric drive unit (EDU) using an interference fit connection. Typically, the stator housing is heated to around 180°C so that the stator bore of the stator housing increases in diameter thereby allowing the stator assembly to be positioned within the stator bore. Upon cooling of the stator housing, the diameter of the stator bore decreases such that the stator is securely held by an interference fit. It is common to use oil, or another suitable coolant fluid, to cool the stator of the EDU in use. Typically, a manifold is located at either end of the stator to define the ends of one or more passages through which coolant flows in use. The manifolds are sealed by resilient seals to prevent the coolant leaking into the main body of the EDU and to maintain pressure in the cooling system. The use of resilient seals presents something of a problem during installation of the stator in the stator housing. This is because the seals must be kept in compression during cooling of the stator housing until a sufficient interference fit is produced between the stator and the stator housing. If the seals are not maintained in compression during cooling, they are able to expand resulting in the cooling system being improperly sealed, and causing the stator to move with respect to the stator housing so that it is incorrectly positioned. In existing manufacturing techniques, the press, which may be a heated press, which is used to position the stator within the stator housing maintains pressure on the stator until the stator housing has cooled sufficiently to fix the stator in place. In this way, the seals are maintained in compression until the stator can no longer move in relation to the stator housing. Although this manufacturing method works well to properly position the stator and properly compress the seals, there is a throughput time penalty as the press cannot be used to install the next stator in the next stator housing until the preceding assembly has cooled. After the stator is installed in the stator housing, an end cover is fixed to one end of the stator housing. The end cover comprises a plurality of support ‘fingers’ which extend from an internal surface of the end cover into abutting engagement with the top surface of the manifold located at that end of the stator housing. The support fingers serve to prevent separation of the manifold from the stator, and to maintain compression of the associated manifold seal. The requirement for support fingers presents a packaging challenge as they must be kept at a certain distance from the stator coil and its associated buss-bar to prevent electrical arcing. 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, an electric motor, a method of assembling a stator assembly, and a vehicle comprising the stator assembly or the electric motor as claimed in the appended claims. According to an aspect of the present invention there is provided a stator assembly for an electric motor for providing drive to a wheel of a vehicle, the stator assembly comprising a stator having a first end and a second end and a stator housing having a first end and a second end. The stator may be received within the stator housing by insertion of the stator into the stator housing in an axial direction with respect to the stator and stator housing. The stator housing may comprise a first recess which extends radially into a surface of the stator housing. A datum may be provided to locate the stator axially with respect to the stator housing. A first manifold may be located adjacent the first end of the stator. A first portion of a resiliently deformable fixing may be located within the first recess and a second portion of the resiliently deformable fixing may extend from the first recess, wherein an abutment surface of the first manifold abuts against the second portion of the resiliently deformable fixing such that axial movement of the first manifold in a first direction in said axial direction is inhibited when the stator is in abutment with the datum. The stator assembly of the present invention is advantageous as the resiliently deformable fixing holds the first manifold in position thereby negating the need for support fingers. In addition, during the installation of the stator in the stator housing, the resiliently deformable fixing holds the stator against the datum and in position during cooling thereby allowing the stator assembly to be removed from the press before the stator housing has cooled and the interference fit has formed. Optionally the first manifold comprises a second recess which extends radially into a surface of the first manifold to define said abutment surface and the resiliently deformable fixing extends into the second recess. This is beneficial as the resiliently deformable fixing may conveniently be held in place in the second recess during the installation of the stator in the stator housing. The resiliently deformable fixing is optionally an incomplete ring such as a circlip, which may also be known as a snap ring. In one example, the stator assembly comprises a resiliently deformable first end seal in compression in said axial direction between the first end of the stator and the first manifold; and a resiliently deformable second end seal in compression in said axial direction between the second end of the stator and a second manifold positioned between the stator and the stator housing, wherein one of the first end seal and the second end seal is limited in its compression by the abutment of the stator with said datum. By compressing one end seal to a greater extent than the other end seal, the stator can be precisely positioned against the datum in the stator housing. The second end seal may be limited in its compression by the abutment of the stator with said datum, said datum comprising a face of said second manifold abutting the second end of the stator, a recess in said face receiving the second end seal. A gap may then exist between a face of the first manifold and the first end of the stator, which gap permits movement of the stator in said first direction, compression of the first end seal sealing the gap and inhibiting movement of the stator in said first direction. The stiffness of the first end seal material may be greater than the stiffness of the second end seal material. In this case, the extent of compression of the first end seal may not exceed that of the second end seal provided that the second end seal, when compressed, results in abutment of the stator against the datum. Optionally the first recess is an annular recess which is readily machinable. The stator housing optionally comprises a frustoconical surface located adjacent the first recess, wherein the frustoconical surface tapers towards the first recess. This is beneficial to help compress the resiliently deformable fixing between the stator housing and the first manifold as it is pushed into the stator housing during manufacture. An adhesive or topical sealant such as a methacrylate-based adhesive may be located between the outermost end of the first manifold and the stator housing to help seal this interface. According to another aspect of the present invention there is provided an electric motor comprising a stator assembly as described above. According to a further aspect of the present invention there is provided a method of assembling a stator assembly, the method comprising: heating the stator housing to cause the diameter of a stator bore of the stator housing to increase; positioning the stator, the first manifold and the resiliently deformable fixing within the stator bore; applying a force to the first manifold to cause the stator to abut the datum to locate the stator in the stator housing in said first direction and to cause the first portion of the resiliently deformable fixing to be received in the first recess of the stator housing; and allowing the stator housing to cool to create an interference fit between the stator and the stator housing. Optionally the force is applied to the first manifold via the resiliently deformable fixing. In this embodiment, the resiliently deformable fixing may be located next to the outermost surface of the manifold rather than in a second recess of the manifold. The second portion of the resiliently deformable fixing may optionally be located in the second recess of the first manifold before the stator, the first manifold and the resiliently deformable fixing are positioned within the stator bore. This provides a convenient way of carrying the resiliently deformable fixing into the stator bore. Applying the force to the first manifold may cause the second recess to align with the first recess such that the first portion of the resiliently deformable fixing is received within the first recess. The force applied to the first manifold may compress the resiliently deformable first end seal and resiliently deformable second end seal until the stator abuts the datum, whereupon further application of the force applied to the first manifold further compresses only one of the first and second end seals. On application of the force, the resiliently deformable fixing may engage the first recess in stator housing before the first manifold abuts the stator, leaving a gap between the first manifold and the stator that is sealed by the resiliently deformable first end seal. Aspects of the present invention relate to a stator assembly for an electric motor for providing drive to a wheel of a vehicle, the stator assembly comprising: a stator having a first end and a second end; a first manifold located adjacent the first end of the stator; a stator housing having a first end and a second end, the stator housing comprising a first recess which extends radially into a surface of the stator housing; and a resiliently deformable fixing, a first portion of the resiliently deformable fixing being located within the first recess and a second portion of the resiliently deformable fixing extending from the first recess, wherein a surface of the first manifold abuts against the second portion of the resiliently deformable fixing such that axial movement of the first manifold in a first direction is inhibited. The first direction may be the direction away from the stator. According to a still further aspect of the present invention there is provided vehicle comprising a stator assembly as described above or assembled employing the method as described above, or an electric motor as described above. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a vehicle in accordance with an embodiment of the invention; Figure 2 shows a cross-sectional view of a prior art EDU; Figure 3 shows a cross-sectional view of a first end of an EDU in accordance with an embodiment of the invention; Figure 4 shows a partial cross-sectional view of the first end of an EDU having a modified arrangement to that shown in Figure 3; and Figure 5 is a magnified view of the manifold arrangement shown in Figure 4. DETAILED DESCRIPTION A vehicle 1 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 1. With reference to Figure 1, the vehicle 1 comprises a body 2 mounted on a subframe (not shown) and wheels 3 mounted for rotation on the subframe. Motive power is provided to a pair of the wheels 3 by electric drive units (EDUs) 10. In the embodiment shown in Figure 1, the EDUs are mounted in the wheels 3 at one end of the vehicle 1. The driven wheels 3 may be the front or rear wheels of the vehicle 1. Alternatively, all of the wheels 3 of the vehicle 1 may be driven by an EDU. In a further alternative, one or more EDUs may be mounted on the subframe of the vehicle 1 and drive may be transferred to two or more of the wheel’s 3 via driveshafts. Figure 2 shows a cross-sectional view of a prior art EDU 10. The EDU 10 comprises a rotor 16 mounted for rotation about an axis of rotation in a stator 20. The stator 20 comprises a stator body 21 which supports a stator coil 22. The rotor 16 is positioned within the stator 20 such that the axis of rotation of the rotor 16 is co-linear with the longitudinal axis 26 of the stator 20, which corresponds to the drive axis of the EDU 10. The stator 20 is fixed within a stator bore 17 of a stator housing 11. The stator housing 11 has a first end 13, which is at the non-drive end of the EDU 10 in Figure 2, and a second end 14, which is at the drive end of the EDU in Figure 2. A stator housing cover 12 is fixed to the first end 13 of the stator housing 11. A plurality of coolant channels 25 pass through the stator body 21, extending from a first end 23 to a second end 24 of the stator body 21. To maintain the pressure of the coolant within the cooling system, a first manifold 30 is located next to the first end 23 of the stator body 21, and a second manifold 40 is located next to the second end 24 of the stator body 21. The first and second manifolds 30, 40 are radially symmetrical about the longitudinal axis 26 of the stator 20. The first manifold 30 is sealed by seals 31 and 32 which are compressed between the first manifold 30 and the first end 23 of the stator body 21 and the stator bore 17 respectively. The second manifold 40 is sealed by seals 41 and 42 which are compressed between the second manifold 40 and the second end 24 of the stator body 21 and the stator bore 17 respectively. The seals 41,42 of the second manifold 40 are maintained in compression by the stator body 21 which is fixed relative to the stator housing 11 by an interference fit with the stator housing 11. The seals 31, 32 of the first manifold 30 are maintained in compression by a plurality of support fingers 15 which extend from an inner surface of the stator housing cover 12 to the outer surface of the first manifold 30. A partial cross-sectional view of an EDU 100 having a stator assembly 101 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figure 3. For the sake of clarity, like reference numerals have been used throughout this description for like components. With reference to Figure 3, the stator assembly 101 comprises a stator housing 11 within which is fixed a stator 20 which comprises a stator coil 22 supported by a stator body 21. Only the first end 13 of the stator housing 11 and the first end 23 of the stator body 21 are shown in Figure 3. The manifold and seal arrangement at the second end 14 of the stator housing 11 and the second end 24 of the stator body 21 are the same as that shown in Figure 2 and described above. A plurality of coolant channels 25 extend through the stator body 21 from the first end 23 of the stator body to the second end 24 of the stator body (see Figure 2). A first manifold 130 is located next to the first end 23 of the stator body 21 adjacent a first recess 111 which extends radially, with respect to the longitudinal axis 26 of the stator 20, into the stator housing 11 from the stator bore 17. The first manifold 130 comprises a second recess 133 which extends radially, with respect to the longitudinal axis 26 of the stator 20, into the first manifold 130. The first 111 and second 133 recesses are aligned with one another and a resiliently deformable fixing 132 is located in the recesses 111, 133. The resiliently deformable fixing 132 acts to hold the first manifold 130 in place with respect to the stator housing 11. A seal 31 is compressed between the first end 23 of the stator body 21 and the first manifold 130. The seal 31 is maintained in compression by the first manifold 130 which is held in place by the resiliently deformable fixing 132. The support fingers 15 of the prior art embodiment (see Figure 2) are therefore no longer needed. The seal between the radially outermost end surfaces of the first manifold 130, on either side of the resiliently deformable fixing 132, are metal to metal seals. A topical sealant or an adhesive may also be used between the end surfaces of the first manifold 130 and the stator bore 17. In the example embodiment of Figure 3, the resiliently deformable fixing 132 is a circlip (which may also be referred to as a snap-ring) which is located in the recesses 111, 133 such that a first portion of the circlip 132 is located within the first recess 111, and a second portion of the circlip 132 is located in the second recess 133. In this embodiment, both the first recess 111 and the second recess 133 are annular recesses which are centred on the longitudinal axis of the stator 20. A circlip is a resilient ring comprising a gap portion such that radially inward pressure applied to the outer edge of the circlip causes the gap to close such that the diameter of the circlip is reduced. Release of the inward pressure then allows the gap to open and the circlip to expand to fit into the recess 111. It will be understood that a different type of resiliently deformable fixing may be used in place of a circlip, or that a stack of circlips may be used. A stack of circlips may be configured to be received in a single pair of first 111 and second 133 recesses. Alternatively, a separate pair of first 111 and second 133 recesses may be provided for each circlip. In a further alternative embodiment, a plurality of discrete resiliently deformable fixings may be spaced around the circumference of the first manifold 130. Optionally, a corresponding number of discrete first 111 and second 133 recesses may be provided to receive the discrete resiliently deformable fixings. During manufacture of the EDU 100 in accordance with an embodiment of the present invention, a stator sub-assembly is assembled comprising the first manifold 130 which is trapped on the stator 20 next to the first end 23 of the stator body 21 by the coils 22. The resiliently deformable fixing 132 is located on the first manifold 130, in the second recess 133, before the stator sub-assembly is positioned within the stator bore 17 of the stator housing 11. The stator housing 11 is heated to a suitable temperature such as around 180°C so that the stator bore 17 increases in diameter. The stator sub-assembly is then positioned in the stator bore 17 by the press which pushes the stator sub-assembly into the stator bore by applying pressure or force to the outermost surface of the first manifold 130. The press may be a heated press such as a ‘hot-drop’ machine. The resiliently deformable fixing 132 is compressed between the first manifold 30 and the stator bore 17 until the second recess 133 aligns with the first recess 111 whereupon the resiliently deformable fixing 132 expands so that a first portion of the resiliently deformable fixing 132 is located within the first recess 111, and a second portion of the resiliently deformable fixing 132 is located within the second recess 133. The second recess 133 therefore forms an abutment surface that limits axial movement of the first manifold with respect to the stator housing and thereby inhibits, as discussed further below, movement of the stator with respect to the stator housing. Once the resiliently deformable fixing 132 is located in the first and second recesses 111,133, the stator sub-assembly is unable to move in a first direction away from the second end 14 of the stator housing 11, and the press no longer needs to apply pressure or force to the stator sub-assembly. The stator assembly 100 may therefore be moved on to the next step in the manufacturing process and the press may be used to install a subsequent stator in a subsequent stator housing. This provides the benefit that the press is made available for assembly of subsequent parts more quickly than with the prior art system. So that the stator 20 does not move with respect to the stator housing 11 under the combined influence of the compressed seals 31, 41, 42 before the stator housing 11 has cooled, the compressed seal 31 located between the first end 23 of the stator body 21 and the first manifold 130 has a greater stiffness than the combined stiffnesses of the compressed seals 41, 42 located on either side of the second manifold 40 (see Figure 2). This is achieved by using sealing material of the same stiffness, but compressing the first end seal 31 more than the send end seals 41,42, and / or by using a stiffer seal material for the first end seal 31. To ensure that the restorative force of the compressed second end seals 41,42 cannot exceed the restorative force of the compressed first end seal 31, the position of the first recess 111 is selected so that when the stator sub-assembly is installed and held in position by the resiliently deformable fixing 132, the second end 24 of the stator body 21 abuts one side of the second manifold 40, and the stator bore 17 abuts the other side of the second manifold 40. That is, the second manifold forms a datum position for the stator 16 when its seals 41, 42 are compressed such that the face of the end 24 of the stator abuts the second manifold 40, which itself abuts the end of the stator housing in the bore 17. In this position the second end seals 41, 42 are trapped in their seats on either side of the second manifold and cannot be compressed any further. The compression of the first end seal 31 between the first manifold 130 and the first end 23 of the stator body 21 is such that the stator body 21 is held against the second manifold 40 until the stator housing 11 has cooled and the interference fit established. As discussed above, the required stiffness / restorative force of the first end seal 31 may be achieved through the extent of compression and / or by using a stiffer material than that used for the second end seals 41,42. In an alternative method of manufacture, the resiliently deformable fixing 132 may be positioned adjacent to the outermost surface of the first manifold 130 rather than in the second recess 133, the outermost surface thereby forming the requisite abutment surface.. The press may apply pressure or force to the outermost surface of the first manifold via the resiliently deformable fixing 132. In this embodiment, the press pushes on the resiliently deformable fixing 132 until it aligns with the first recess 111 in the stator housing 11. Upon alignment of the resiliently deformable fixing 132 with the first recess 111, a first portion of the resiliently deformable fixing 132 expands into the first recess, and a second portion of the resiliently deformable fixing abuts the outermost surface of the first manifold 130 to prevent it moving in the first direction away from the second end 14 of the stator housing 11. In this embodiment, the first manifold 130 need not comprise the second recess 133. A partial cross-sectional view of an EDU 200 having a stator assembly 201 in accordance with an alternative embodiment of the present invention is described herein with reference to the accompanying Figure 4. With reference to Figure 4, (see also more detail in Figure 5) the stator assembly 201 comprises a stator housing 211 (11 in Figure 5) within which is fixed a stator 20. In this embodiment the stator bore 17 of the stator housing 211 comprises a frustoconical section 218 located proximate the first recess 111. The frustoconical section 218 helps to compress the resiliently deformable fixing 132 as it is pushed along the stator bore during manufacture in order to apply a radially inward pressure to the outer edge of the resiliently deformable fixing 132 such that the dimension of the resiliently deformable fixing 132 is reduced. The stator assembly 201 may also comprise a seal 135 which is compressed between the first manifold 130 and the stator bore 17. The seal 135 may be used alone or may be used in addition to a metal / metal seal between the radially outermost surfaces of the first manifold 130 and the stator bore 17 and / or a chemical sealant or adhesive. The seal 135 may be used in the embodiment of Figure 3 if desired. With further reference to Figure 5, it is to be noted that a gap 137 exists between the first manifold 130 and the end 23 of the stator body 21. This gap is sealed by the seal 31 compressed against the end 23 of the stator by the first manifold 30. The gap is provided to allow for the tolerance in manufacture of the stator housing (in particular the position of its first recess 111 and bore 17) the first and second manifolds 30, 130, 40, and the stator body 21. Thus, on assembly, as the stator body is inserted into the stator housing and pressure or force applied against the first manifold 30,130, and the several components (being the first manifold 130, stator body 21, second manifold 40 and stator bore 17) make contact with each other, the seals 31, 41, and 42 are initially all compressed until forward and rearward faces of the second manifold make contact respectively with a shoulder in the bore 17 and the end 24 of the stator body 21. At this point, the stator 20 is correctly located in the stator housing and further compression of the seals 41, 42 ceases. On further application of force against the first manifold 130, the gap 137 progressively closes, and the seal 31 is further compressed, until the resiliently deformable fixing 132 snaps into engagement with the stator housing recess 111, before gap 137 is completely closed. The force is applied against a rear face 141 of the first manifold but, as described above, rather than locating the resiliently deformable fixing 132 in the second recess 133 of the manifold 130, the wall 141 defining the recess can be omitted, as shown by dotted line 143 in Figure 5. In this event, the force is applied to the resiliently deformable fixing 132 and transferred to the first manifold by a rearward facing front wall 139 of the manifold. Finally, as described above, a manufacturing tolerance in the dimensions of the parts of the stator housing assembly is provided by the gap 137 being disposed between the face of the first manifold 130 and the first end 23 of the stator, with the datum that locates the stator axially with respect to the stator housing being provided by the second manifold abutting both the second end of the stator and second end of the stator housing, with both seals 41,42 being fully compressed. Thus, any variation in manufacturing tolerance is accommodated by a greater or lesser compression of the first seal 31 and variation in the width of the gap 137. However, it should be appreciated that the datum could be defined by the first manifold 30, 130, with the first seal 31 being fully compressed and the face of the first manifold abutting the first end of the stator. In this event, the tolerance gap could be provided by the second manifold 40 between the second end 24 of the stator 20 and stator housing 11. Either or both of the seals 41,42 would not be fully compressed but allow a tolerance gap while still sealing the second manifold with respect to the stator and stator housing. In this respect, while the seals 41, 42 are shown as being axially compressed seals, the seal 42 at least could be a radially compressed seal. 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.

Claims

1. A stator assembly for an electric motor for providing drive to a wheel of a vehicle, the stator assembly comprising:a stator having a first end and a second end;a stator housing having a first end and a second end, the stator being received within the stator housing by insertion of the stator into the stator housing in an axial direction with respect to the stator and stator housing, the stator housing comprising a first recess which extends radially into a surface of the stator housing, a datum being provided to locate the stator axially with respect to in the stator housing;a first manifold located adjacent the first end of the stator; anda resiliently deformable fixing, a first portion of the resiliently deformable fixing being located within the first recess and a second portion of the resiliently deformable fixing extending from the first recess,wherein an abutment surface of the first manifold abuts against the second portion of the resiliently deformable fixing such that axial movement of the first manifold in a first direction in said axial direction is inhibited, the stator being in abutment with the datum.

2. A stator assembly according to claim 1, wherein the first manifold comprises a second recess which extends radially into a surface of the first manifold to define said abutment surface and the resiliently deformable fixing extends into the second recess.

3. A stator assembly according to claim 1 or claim 2, wherein the resiliently deformable fixing is a circlip.

4. A stator assembly according to any preceding claim comprising:a resiliently deformable first end seal in compression in said axial direction between the first end of the stator and the first manifold; anda resiliently deformable second end seal in compression in said axial direction between the second end of the stator and a second manifold positioned between the stator and the stator housing,wherein one of the first end seal is limited in its compression by the abutment of the stator with said datum.

5. A stator assembly according to claim 4, wherein the second end seal is limited in its compression by the abutment of the stator with said datum, said datum comprising a face ofsaid second manifold abutting the second end of the stator, a recess in said face receiving the second end seal.

6. A stator assembly according to claim 5, wherein a gap exists between a face of the 5 first manifold and the first end of the stator, which gap permits movement of the stator in said first direction, compression of the first end seal sealing the gap and inhibiting movement of the stator in said first direction.

7. A stator assembly according to claim 4, 5 or 6, wherein the stiffness of the first end 10 seal is greater than the stiffness of the second end seal.

8. A stator assembly according to any preceding claim, wherein the first recess is an annular recess.15 9. An electric motor comprising a stator assembly according to any preceding claim.

10. A method of assembling a stator assembly according to any one of claims 1 to 9, the CM method comprising:CM heating the stator housing to cause the diameter of a stator bore of the stator'^“20 housing to increase;CO positioning the stator, the first manifold and the resiliently deformable fixing within thestator bore;applying a force to the first manifold to cause the stator to abut the datum to locate the stator axially in the stator housing in said first direction and to cause the first portion of the 25 resiliently deformable fixing to be received in the first recess of the stator housing; andallowing the stator housing to cool to create an interference fit between the stator and the stator housing.

11. A method according to claim 10, wherein the force is applied to the first manifold via 30 the resiliently deformable fixing.

12. A method according to claim 10, when dependent on claim 2, wherein the second portion of the resiliently deformable fixing is located in the second recess of the first manifold before the stator, the first manifold and the resiliently deformable fixing are positioned within 35 the stator bore.

13. A method according to claim 10, 11 or 12, when dependent on claim 4 or on any of claims 5 to 10 that depend through claim 4, wherein the force applied to the first manifold compresses the resiliently deformable first end seal and resiliently deformable second end seal until the stator abuts the datum, whereupon further application of the force applied to the 5 first manifold further compresses only one of the first and second end seals.

14. A method according to claim 13, when dependent on claim 6, wherein, on application of the force, the resiliently deformable fixing engages the first recess in stator housing before the first manifold abuts the stator, leaving a gap between the first manifold and the stator that 10 is sealed by the resiliently deformable first end seal.

15. A vehicle comprising a stator assembly according to any one of claims 1 to 8 or comprising an electric motor according to claim 9.13 1224

Images