Technical Field

The present disclosure generally relates to drive mount arrangements for use on electric vehicles.

Background

Drive mounts are used in electric vehicles (EVs) (such as electric cars, electric vans, electric lorries, e-motorbikes and e-bicycles) for coupling a drive wheel with a chassis of the electric vehicle and a radial flux electric motor. In conventional four-wheel EVs, the radial flux electric motor is installed in the position of the engine in gasoline engine vehicles, and transfers power to the wheels via a drive shaft. However, EVs generally require a large volume of space across the base of their bodies for housing battery modules.

Unfortunately, these conventional centralised radial flux electric motor and drive shaft assemblies occupy a significant volume of space across the body of the EV, which could be better served to house battery modules.

In-wheel motor assemblies utilise radial flux electric motors installed directly adjacent to each of the drive wheels, and are configured to deliver power to the drive wheels via very short or no distinct drive shafts. However, due to the size requirements of radial flux electric motors, even in-wheel motor assemblies can still extend into the body of EVs, reducing the space available for housing battery modules.

Two-wheel EVs (such as e-bicycles and e-motorbikes) typically utilise drive mounts comprising a swing arm assembly for coupling a drive wheel to a radial flux electric motor and a chassis of the EV. A pivotable coupling is provided between the swing arm and the EV chassis to allow movement of the swing arm relative to the EV chassis in a vertical direction for suspension purposes. Generally, two-wheel EVs use an in-wheel motor arrangement, similar to that described above for delivering power to the drive wheel. However, the mounting of a radial flux electric motor on the side of the drive wheel on a two-wheel EV can cause a significant weight imbalance on one side of the EV, thereby reducing driving performance. Furthermore, as described above, the use of in-wheel radial flux motors may significantly increase the width of the overall drive mount assembly which is particularly undesirable for two-wheel EVs. Some swing arm assemblies comprise a radial flux electric motor which is offset from the axis of rotation of the drive wheel towards a central portion along the length of the EV, thereby redistributing the weight of the radial flux electric motor towards the middle of the EV’s length. In such cases, the swing arm may comprise a drive coupling to facilitate power transfer between the radial flux electric motor and the drive wheel. While this swing arm arrangement may improve weight distribution along the length of the EV, it does not improve weight distribution across the width of the EV, since the radial flux electric motor is still mounted on one side of the swing arm.

There therefore remains a need for an improved drive mount solution for EVs. The present disclosure addresses one or more deficiencies associated with the known drive mount arrangements.

Summary of the Disclosure

Embodiments described herein provide drive mount arrangements and assemblies for use on electric vehicles.

According to a first aspect of the present disclosure, provided is a drive mount for an electric vehicle, the drive mount comprising a chassis end for connection with a chassis portion of the electric vehicle; a wheel end for coupling the drive mount with a drive wheel of the electric vehicle; and a motor housing portion, for housing an axial flux electrical machine, wherein the drive mount is configured such that when the drive wheel is coupled to the wheel end, the motor housing portion is radially offset from the drive wheel and a radial plane X extending through the drive wheel intersects the axial flux electrical machine when housed in, or on, the motor housing portion.

The provision of a drive mount comprising a motor housing portion configured to house an axial flux electric motor may advantageously reduce the width requirements of the drive mount, since the width requirements of an axial flux electric motor is smaller than that of an equivalent radial flux electric motor having the same power output. Furthermore, alignment of the drive wheel and the axial flux electrical machine along the length of the drive mount may improve weight distribution across the width of the drive mount and ensure that the overall width of a drive mount assembly including the drive mount and the drive wheel is minimised. Throughout this disclosure, unless otherwise qualified, terms such as “radial”, “axial”, “circumferential” and “angle” are used in the context of a cylindrical polar coordinate system (r, &, z) in which the direction of the axis of rotation of the electric motor or drive wheel is parallel to the z-axis. That is, “axial” means parallel to the axis of the rotation (that is, along the z-axis), “radial” means any direction perpendicular to the axis of rotation, an “angle” is an angle in the azimuth direction &, and “circumferential” refers to the azimuth direction around the axis of rotation.

Terms such as “radially extending” and “axially extending” should not be understood to mean that a feature must be exactly radial or exactly parallel to the axial direction. To illustrate, while it is well-known that the Lorentz force experienced by a current carrying conductor in a magnetic field is at a maximum when the direction of the current is exactly perpendicular to the direction of the magnetic flux, a current carrying conductor will still experience a Lorentz for angles less than ninety degrees. Deviations from the parallel and perpendicular directions will therefore not alter the underlying principles of operation.

The motor housing portion may be configured such that an axis of rotation of the axial flux electrical machine when housed within the motor housing portion is situated closer to the chassis end than the wheel end of the drive mount. This enables the axial flux machine to be housed closer to the centre of the electric vehicle (EV) to improve weight distribution along the length of the EV.

The motor housing portion may be configured to structurally connect the chassis end to the wheel end, wherein the motor housing portion is situated between the chassis end and the wheel end of the drive mount.

The motor housing portion may be integral to at least one of the chassis end or the wheel end of the drive mount. Advantageously, the integral motor housing portion may reduce the weight and or volume of the drive mount by avoiding the need for additional coupling means (e.g., nuts, bolts & connectors). The motor housing portion may be integral to the chassis end and the wheel end of the drive mount.

The motor housing portion may be configured for removable connection with at least one of the chassis end or the wheel end. Removability of the motor housing portion from other components of the drive mount may ease assembly of drive mount onto the EV and improve maintenance access to portions of the drive mount. It will be appreciated that any known means suitable for achieving removable connection between components of the drive mount may be utilised.

The motor housing of the drive mount may comprise a cover portion of an electrical motor, the cover portion being configured to couple to the electrical motor. The motor housing cover portion may be configured to form an end plate of the electrical motor to cover a rotor of the electrical motor and seal against a stator housing of the electrical motor.

The drive mount may be single-sided, in which only one side of the wheel end engages with the drive wheel. Alternatively, the drive mount may be double-sided, in which the wheel end engages both sides of the drive wheel. For a single-sided drive mount, the motor housing portion may be configured to house an axial flux electrical machine on the same side of the drive mount as the drive wheel coupled to the wheel end. This may reduce torsional forces on the drive mount and improve weight distribution across the width of the EV.

The drive mount may be configured such that the radial plane X extends through a midportion across the width of the drive wheel so that the axial flux electrical machine aligns with the centre of the drive wheel. Additionally, or alternatively, the drive mount may be configured such that the radial plane X intersects a centre of gravity of the axial flux electrical machine when housed within the motor housing portion to further improve the weight distribution across the drive mount.

The drive mount may comprise a drive coupling between the axial flux electrical machine when housed within the motor housing portion and the drive wheel when coupled to the wheel end of the drive mount. The drive coupling being configured to transfer power from the axial flux electrical machine to a drive wheel when coupled to the wheel end of the drive mount. The drive coupling may comprise one of a belt drive, a chain drive, or a shaft drive. The drive coupling may comprise a transmission having a gear reduction ratio between 1 and 10. Preferably, the transmission has a gear reduction ratio between 2 and 4. The transmission may comprise multi-stage gear reduction. Multi-stage transmissions offer higher gear ratios and are more compact than the equivalent single-stage transmissions. Therefore, use of a multi-stage transmission may reduce the overall width of the drive mount.

The motor housing portion may comprise a cooling passage for a cooling fluid to cool an axial flux electrical machine housed within the motor housing portion. The cooling passage may form a closed loop leading to a heat sink for removing heat from the cooling fluid. The heat sink may comprise cooling fins on an outer surface of the drive mount.

The motor housing portion may be formed by extrusion. Extrusion enables complex geometry components of the motor housing portion to be manufactured at lower production cost compared to other forms of manufacture such as machining. Extrusion of the motor housing portion may also reduce the required amount of coupling means between components of the motor housing portion, thereby reducing the overall weight of the drive mount. The motor housing portion may be extruded as a single part. The motor housing portion may be formed of a plurality of circumferentially-interlocking extruded segments.

The chassis end may be configured for pivotal connection with the chassis portion of the electric vehicle to allow movement of the drive mount relative to the EV chassis in a vertical direction for operation with a suspension system.

The drive mount may be configured as a swing arm for a two-wheel EV. For example, the chassis end may be configured to engage a rear portion of one of an e-bicycle or an e- motorbike and the wheel end may be configured to engage a rear drive wheel of the e- bicycle or e-motorbike. When configured for a two-wheel EV, the drive mount may be configured such that, when coupled to the EV, the motor housing portion is positioned ahead of the drive wheel. This may help redistribute the weight of the axial flux electrical machine towards the middle across the length of the two-wheel EV.

The drive mount may be configured for a four-wheel electric vehicle. For example, the chassis end may be configured to engage a corner portion of the chassis of one of an electric car, an electric van or an electric lorry. Accordingly, the wheel end may be configured to engage a wheel of the respective EV. When configured for a four-wheel EV, the drive mount may be configured such that, when coupled to the EV, the motor housing portion is positioned above the drive wheel. This may advantageously reduce the width of the drive mount assembly including the drive mount and the drive wheel to free up the space across the width of the EV for housing battery modules or other components, or to provide additional load capacity.

In a second aspect, the disclosure provides a drive mount assembly comprising: a drive mount according to any of the examples described above; a drive wheel coupled to the wheel end of the drive mount; and an axial flux electrical machine housed within the motor housing portion of the drive mount. The drive mount assembly may comprise a mechanical break assembly for operation on the drive wheel.

The drive mount assembly may comprise a suspension mount for operation with the chassis of the EV.

The axial flux electrical machine may comprise a stacked axial flux electrical machine assembly. The axial flux electrical machines may be internally stacked or externally stacked. Stacked electrical motors may provide additional power to the drive wheel. An internally stacked axial flux electrical machine may advantageously provide additional power while occupying less space than the equivalent externally stacked arrangement.

In a third aspect, the disclosure provides an electric vehicle (EV) comprising at least one drive mount assembly according to any of the above described examples. The EV may be any one of an electric car, an electric van, an electric lorry, an e-bicycle or an e-motorbike.

The EV may comprise a plurality of drive mount assemblies according to the above described examples. For example, a four-wheel EV may comprise two or four drive mount assemblies based on whether a two wheel drive or four wheel drive system is required.

Stator housing

The motor housing portion according to any of the above examples may comprise a stator housing for housing a stator of the axial flux electrical machine. The motor housing portion may comprise one or more cover plates for covering one or more rotors of the axial flux electrical machine when housed within the motor housing portion.

Preferably, the stator housing is integral to the motor housing portion. In some configurations, the stator housing is extruded from the motor housing portion of the drive mount. Providing an integral stator housing within the drive mount may help reduce the overall weight of the drive mount.

The stator housing is preferably tubular and substantially cylindrical in shape, wherein the inner surface of the stator housing comprises a plurality of recesses, each recess configured to receive an outer part of a conductive coil of the stator of the axial flux electrical machine.

The cross-section of each recess, perpendicular to the axis of rotation of the axial flux electrical machine, is preferably elongate, the major dimension of each elongate recess extending substantially in the radial direction of the axial flux electrical machine. Each elongate recess preferably has an aspect ratio of between about 5 and about 15. The aspect ratio of each recess may be between about 6 and about 12, more preferably between about 7 and about 10.

The side walls of each recess are preferably substantially parallel to the rotational axis of the axial flux electrical machine.

The circumferential distance between adjacent recesses is preferably between about 1 times and about 3 times the width of each recess.

The stator housing preferably further comprises an annular ring configured to form an annular channel adjacent the circumferential outer surface of said stator housing. The stator housing preferably further comprises a spacer configured to divide said annular channel, the spacer extending from a first axial end of said stator housing to a second axial end of said stator housing. In this way, the spacer positions the annular ring relative to the stator housing outer surface to form the annular channel, and divides the annular channel such that it forms a C- shape. The spacer preferably mechanically couples the stator housing to the annular ring. The annular ring preferably comprises a cooling fluid inlet disposed adjacent a first side of said spacer, and a cooling fluid outlet disposed adjacent a second side of said spacer, the inlet and the outlet being in fluid communication with the annular channel. As will now be appreciated, the spacer divides the annular channel such that cooling fluid flow proceeds circumferentially around the annular channel. The annular ring preferably forms a portion of the cooling passage of the drive mount described above.

In this preferred example, the plurality of recesses is preferably formed from a first set of protrusions extending from the inner surface of the stator housing and a second set of protrusions extending from the inner surface of the stator housing, wherein the first set of protrusions are formed integrally with said stator housing, and the second set of protrusions are formed separately and positioned within said stator housing.

The second set of protrusions are preferably mechanically attached to said stator housing. The first set of protrusions are preferably interlaced with said second set of protrusions. Advantageously, forming the stator housing and recesses in this manner improves the manufacturability of the stator housing. The minimum thickness of any feature of the extrusion tool used to form the stator housing may be increased, such that the tool life is significantly increased. The first set of protrusions are preferably interlaced with said second set of protrusions such that each protrusion from the first set of protrusions is adjacent a protrusion from the second set of protrusions.

Each of the second set of protrusions may comprise a key configured to engage with a corresponding slot formed in the inner surface of the extruded stator housing to mechanically attach each protrusion thereto. In some configurations, each of the second set of protrusions comprises a slot configured to engage with a corresponding key formed on the inner surface of the extruded stator housing to mechanically attach each protrusion thereto.

The second set of protrusions may be formed by extrusion. The stator housing may be extruded as a single part. That is to say, the main tubular body of the stator housing may be formed as a single part. Alternatively, the stator housing may be formed of a plurality of circumferentially-interlocking extruded segments. In an example, the housing may be extruded as a plurality of interlocking arcuate segments. The housing may be formed of two, three, four, five or more interlocking arcuate segments. In one further example, the extruded housing may be formed of two sections, a first outer section and a second inner section, the inner section comprising the plurality of recesses. The inner section may comprise a plurality of sub-sections, each sub-section comprising at least one recess. The second inner section preferably interlocks with said first outer section.

When the stator housing comprises an annular ring, the annular ring is preferably formed by extrusion. When the annular ring is spaced apart from the outer surface of the tubular body of the stator housing by a spacer, the spacer is preferably formed of a slot and key, the slot being formed on one of an inner surface of said annular ring and the outer surface of said stator housing, the key being formed on the other of the inner surface of said annular ring and the outer surface of said stator housing.

Preferably, the extruded stator housing has an outer surface which is shaped so as to increase the overall surface area of the outer surface of the extruded stator housing.

The stator housing may further comprise at least one recess or channel in which a fluid cooling arrangement is accommodated. Alternatively, the stator housing may comprise at least two recesses or channels, in which the fluid cooling arrangement is accommodated, arranged on opposed axial ends of said stator housing. Preferably, the fluid cooling arrangement is fluidly coupled with the cooling passage of the drive mount described above. The or each recess or channel may be substantially annular. The or each recess or channel may be substantially adjacent the outer parts of conductive coils in a stator of an axial flux electrical machine when mounted within the stator housing of the drive mount.

An inner surface of the stator housing preferably comprises a plurality of recesses, each recess configured to receive at least an outer part of a conductive coil of a stator of an axial flux electrical machine. Each recess is preferably elongate, the major dimension of each elongate recess extending substantially in the radial direction of the axial flux electrical machine. The sides of each recess are preferably substantially parallel to the rotational axis of the axial flux electrical machine. The circumferential distance between adjacent recesses is preferably between about 1 times and about 3 times the width of a recess.

The fluid cooling arrangement within the stator housing may comprise a pipe for receiving cooling fluid, the pipe being in contact with the housing or, in addition, via a thermally conductive material to improve the heat transfer between the housing and the pipe. The thermally conductive material may be one of: a resin; a paste; or a putty.

Preferably, the pipe forming the fluid cooling arrangement provides an inlet and outlet on an outer face of the stator housing for coupling with the cooling passage described above.

Alternatively, the recess or channel may be configured to directly receive cooling fluid, the housing further comprising at least one plate configured to seal said at least one recess or channel.

The stator housing may further comprise at least one further channel provided on an axial end of said stator housing. Preferably said further channel is in fluid communication with said at least one recess or channel. The further channel may be axially located between a rotor of an axial flux electrical machine and a controller of the axial flux electrical machine. In this way, the single fluid cooling arrangement may cool both the axial flux electrical machine and the controller for the axial flux electrical machine.

The stator housing may yet further comprise an external annular channel provided adjacent the circumferential face of said stator housing. Preferably, the external annular channel is in fluid communication with the or each other recess or channel.

The stator housing may be formed by extrusion as described above, the at least one recess or channel being subsequently machined. The stator housing may comprise circumferentially distributed and axially extending apertures for receiving the outer parts of the conductive coils that are substantially parallel to the axis of rotation. As noted above, this provides for easier and more accurate manufacture and heat transfer from the conductive components of the stator through the stator housing.

The drive mount preferably comprises a controller housing for housing a controller for controlling the axial flux electrical machine when housed in the drive mount. Preferably, the cooling passage is further configured such that cooling fluid flowing through the cooling passage cools the controller when housed within the drive mount.

The stator housing is preferably tubular and substantially cylindrical in shape, wherein the inner surface of the stator housing comprises a plurality of recesses, each recess configured to receive an outer part of a conductive coil of the stator of the axial flux electrical machine.

Any feature in one aspect of the disclosure may be applied to other aspects of the disclosure, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the disclosure can be implemented and/or supplied and/or used independently.

Brief Description of the Drawings

Embodiments of the disclosure will now be further described by way of example only and with reference to the accompanying figures in which:

Figure 1 is a side view of a drive mount according to an embodiment of the disclosure;

Figure 2(a) is a top view of a drive mount assembly comprising the drive mount of Figure 1 , and further including an axial flux electrical motor and a drive wheel;

Figure 2(b) is a side view of the drive mount assembly shown in Figure 2(a); Figure 3 is a side view of a drive mount according to a further embodiment of the disclosure;

Figure 4 is a side view of a drive mount assembly according to a yet further embodiment of the disclosure;

Figure 5 is a perspective view of a stator assembly, including a stator housing that houses the conductive coils of a stator assembly;

Like reference numbers are used for like elements throughout the description and figures.

Detailed Description

Figure 1 illustrates a drive mount 100 according to an embodiment of the disclosure. Drive mount 100 comprises a wheel end 102, a chassis end 104 and a motor housing portion 106 separating wheel end 102 from chassis end 104. The drive mount further comprises a drive coupling (not shown) housed with the mount body 108. The drive coupling is configured to connect an output of an electrical motor coupled to the motor housing portion 106 to a drive wheel mounted at the wheel end 102 via a mount 110. The drive mount further comprises a chassis mount portion 112 provided at the chassis end of the drive mount.

Figure 2(a) shows a top view of a drive mount assembly 200, comprising the drive mount 100 shown in Figure 1 . Coupled to wheel end 102 is a drive wheel 202. Motor housing portion 106 is radially offset from drive wheel 202 towards chassis end 104. Chassis end 104 comprises the chassis mount portion 112 for coupling to a chassis portion of a two- wheel electric vehicle, such as an e-bicycle or e-motorbike. Housed within, or on, motor housing portion 106 is an axial flux electrical motor 204. The drive mount body 108 is formed of a first main portion 203a and a second cover portion 203b fixedly coupled thereto. The first main portion 203a comprises projecting ribs to increase structural rigidity of the drive mount. In this example, the projecting ribs are provided in a cross pattern. As described above, the drive mount 100 comprises a drive coupling (not shown), provided within the first main portion 203a, for transferring power from axial flux electrical motor 204 to drive wheel 202. The drive coupling may comprise one of a belt drive, a chain drive, or a shaft drive. The drive coupling may comprise a transmission, the may comprise a multistage gear reduction. Drive mount assembly 100 further comprises a brake assembly 206 situated between drive mount 100 and drive wheel 202; shown in Figure 2(b). As seen in Figure 2(a), drive mount 100 is configured to align motor housing portion 106 with drive wheel 202 such that radial planes X _-n passing through drive wheel 202 in a direction perpendicular to the axis of rotation z of drive wheel 202 intercept motor housing portion 106. A central radial plane X _c may pass through a centre of gravity of the assembly of motor housing portion 106 and electric motor 204.

Figure 3 shows an alternative drive mount 300. Similarly to drive mount 100, drive mount 300 comprises a wheel end 302, and a chassis end 304. In this example, the motor housing portion comprises an integrally formed stator housing 306 for a stator of an electrical motor (not shown). The integrally formed stator housing is provided between the wheel end 302 and chassis end 304. The drive mount further comprises a drive coupling (not shown) housed with the mount body 308. The drive coupling is configured to connect an output of an electrical motor integrally provided within the drive mount to a drive wheel mounted at the wheel end 102 via the stator housing 306. The drive mount further comprises a chassis mount portion 310 provided at the chassis end 304 of the drive mount 300. The chassis mount portion may be integrally formed with the drive mount, or fixedly connected thereto. The drive mount body 308 is formed of a first main portion and a second cover portion fixedly coupled thereto. The first main portion comprises projecting ribs to increase structural rigidity of the drive mount. In this example, the projecting ribs are provided in a cross pattern. The stator housing is integrally formed with the first main portion of the drive mount.

The drive mount 300 may be used in forming an alternative to drive mount assembly 200.

Figure 4 illustrates a front view of a further drive mount assembly 400 similar to those described above. Drive mount assembly 400 comprises a drive mount 402 having a wheel end 404, a motor housing portion 406 and a chassis end 408. Coupled to wheel end 404 is a drive wheel 410. Motor housing portion 406 is radially offset from drive wheel 410. Chassis end 408 comprises a mount 412 for coupling to a chassis portion of a four-wheel electric vehicle, such as an electric car, electric van, or electric lorry. Housed on, or within, motor housing portion 408 is an axial flux electrical motor. Drive mount 400 comprises a drive coupling (not shown) for transferring power from an axial flux electrical motor to drive wheel 410. Drive coupling may comprise one of a belt drive, a chain drive or a shaft drive. As will be appreciated, the drive mount 400 may comprise an integral stator housing for a stator of an axial flux electrical motor, similar to that as described above with reference to Figure 3. Stator housing

Turning to Figure 5, there is illustrated an axial flux electrical machine (motor) stator assembly 500 which can be seen to include an annular or ring-shaped stator housing 520 which houses the conductive coil components 510 of the stator 500. The active region of the stator assembly 500, where the axial flux provided by the rotor magnets interacts with the radially flowing current flowing through the conductive coil components 510 to generate the torque that causes rotors to rotate, includes radially extending active sections of the conductive coil components 510 of the stator and flux guides in the form of lamination stacks. The flux guides, which may comprise grain-oriented electrical steel sheets surrounded by electrical insulation, are positioned in spaces between the radially extending active sections of the conductive components 510 of the core. The flux guides act to channel the magnetic flux produced by the permanent magnets between the current carrying conductors.

The stator housing 520 may be provided with a plurality of circumferentially spaced apart axially extending apertures 525 for receiving the coils. This makes the positioning of the coils in the stator housing easier and more precise. Advantageously, if the coils are formed so as to have an axially extending outer part, the axially extending outer part can be received within the axially extending apertures 525. Since the axially extending outer parts have a large surface area, they provide good mechanical locking of the coils in the stator housing for assembly and also provide a source of cooling of the stator. As will be appreciated, the stator housing 520 may be integrally formed with the drive mount as described above.

Axial flux electrical motors comprising the stator assembly 500 described herein have been found to provide not only a high peak efficiency, but a high efficiency over a broad range of operating parameters. While high peak efficiencies are often quoted, they are in practice rarely achieved, especially in applications where the motor is required to perform over a range of operating parameters. Efficiency over a broad range of parameters is therefore a more practically meaningful measure for many applications.

The axial flux electrical motor described herein may comprise an extruded stator housing, such that the conductive coils of the stator assembly 500 are provided within the housing. As can be seen in Figure 5, but also Figure 3, the housing 520 is generally tubular and cylindrical in shape, with an inner face and an outer face. The outer face may be shaped so as to increase the overall surface area of the outer face of the extruded housing, such as including cooling fins or a heat sink formed therein. Where the stator housing is formed integrally with the drive mount main portion it may be formed by casting. Alternatively, the stator housing may be formed of an inner part for receiving the electrically conductive coils of the stator, and an outer part integrally formed with the drive mount. A channel may be provided between the inner part and the outer part to provide cooling by passing a fluid coolant, such as water, through the channel.

The coils of the stator are encased within a potting compound which has a high heat transfer capacity, to promote efficient heat energy transfer from the coils of the stator. In addition, a thermal paste or heat transfer compound may be placed between the flat section of each of the coils and the inner face of the extruded housing to increase the heat transfer capacity further.

The heat energy may then be dissipated into the air, through the cooling fins or heat sink of the outer face of the extruded housing.

The extruded housing may also include a recess, channel, or similar in which to accommodate a fluid cooling arrangement. This fluid cooling arrangement may be used to increase the rate at which heat energy may be dissipated from the axial flux electrical machine, and therefore to improve the cooling performance of the axial flux machine. Advantageously, the recess, or channel, may be provided such that it is immediately adjacent to the curved portion of the outer sections of the coils.

Fluid cooling, for example water cooling, may deliver more effective cooling performance than air cooling. This is because water has a greater specific heat capacity than air, and the specific heat capacity of water is over four times greater than that of air.

Such a fluid cooling arrangement is shown in Figure 5. The fluid cooling arrangement within the extruded housing 500 may, for example, comprise a pipe formed of a material with high heat conductivity properties, such as copper, and may be in contact with the extruded housing directly, or additionally, via a thermal paste or putty to improve the heat transfer between the extruded housing and the pipe. The pipe forming the fluid cooling arrangement provides an inlet and outlet on the outer face of the extruded housing. A further pipe is provided on the opposite face of the extruded housing, and provides a similar inlet and outlet. Cooling water is fed into the inlets of each pipe, and removed from the outlets of the pipe. The cooling water is supplied into the inlet of the pipe at a reduced temperature, and may be fed out of the outlet into a radiator, heat exchanger, phase-change cooler or similar, before returning to the inlet. This may be considered a cooling ‘circuit’. If the axial flux electrical machine is to be used, for example, in a vehicle, the heat energy transferred from the axial flux electrical machine into the cooling water may be used to heat the cabin of the vehicle, or to maintain the temperature of the battery packs of the vehicle, by way of a heat exchanger.

The cooling fins and/or heatsink may be employed in combination with a fluid cooling arrangement in order to maximise the rate at which the heat energy may be dissipated from the axial flux electrical machine.

The cooling circuit may be a closed loop system, such that the cooling fluid, for example water, is passed into the inlet of the cooling arrangement within the extruded housing, around the cooling channel which may form the cooling arrangement, and out of the outlet of the cooling arrangement, into a radiator, heat exchanger or similar (to transfer the heat energy from the cooling fluid into the air, or to another cooling or heating system, likely through a pump, and then back in to the inlet of the cooling arrangement.

In the case that the cooling circuit is a closed loop system, and the loop includes a radiator, the radiator may include forced cooling in the form of a fan or fans, to promote airflow through the radiator and to improve the cooling performance of the cooling circuit. In a preferred example, the cooling circuit comprises a circumferential channel extending between an inner portion of the stator housing and an outer portion of the stator housing. The outer portion and/or the inner portion of the stator housing may be integral with the drive mount.

As mentioned above, in the case of a vehicle, the heat may be transferred from the axial flux electrical machine cooling circuit and into, for example, the heating circuit of the vehicle, or a heater to maintain the temperature of the battery pack of the vehicle.

Maintaining the temperature of a battery pack in a vehicle may increase the performance of the battery pack; a low temperature may reduce the performance of the battery pack, thus reducing the range of the vehicle.

In a further example, an axial flux electrical machine is mechanically affixed to a controller such that the controller and axial flux electrical machine form a single unit, and the cooling arrangement in the axial flux machine is configured to cool both the axial flux machine and the controller. In this example, a cooling plate may be provided between the axial flux electrical machine and the controller, the cooling plate being hollow or comprising a fluid channel and having an inlet and outlet for connection to a cooling circuit, or the like.

The following clauses define further preferred embodiments of the disclosure.

E1 . A drive mount for an electric vehicle, the drive mount comprising: a chassis end for connection with a chassis portion of the electric vehicle; a wheel end for coupling the drive mount with a drive wheel of the electric vehicle; and a motor housing portion, for housing an axial flux electrical machine, wherein the motor housing portion comprises a stator housing for receiving a stator of the axial flux electrical machine, wherein the stator housing is tubular and substantially cylindrical in shape, the inner surface of the stator housing comprising a plurality of recesses, each recess configured to receive an outer part of a conductive coil of the stator of the axial flux electrical machine, wherein the drive mount is configured such that when the drive wheel is coupled to the wheel end, the motor housing portion is radially offset from the drive wheel and a radial plane X extending through the drive wheel intersects the axial flux electrical machine when housed in the motor housing portion.

E2. The drive mount according to E1 , wherein the cross-section of each recess, perpendicular to the axis of rotation of the axial flux electrical machine, is elongate, the major dimension of each elongate recess extending substantially in the radial direction of the axial flux electrical machine.

E3. The drive mount according to E2, wherein each elongate recess has an aspect ratio of between about 5 and about 15.

E4. The drive mount according to any previous E, wherein the side walls of each recess are substantially parallel to the rotational axis of the axial flux electrical machine.

E5. The drive mount according to any previous E, wherein the circumferential distance between adjacent recesses is between about 1 times and about 3 times the width of each recess. E6. The drive mount according to any previous E, further comprising an annular ring configured to form an annular channel adjacent to the circumferential outer surface of said stator housing.

E7. The drive mount according to E6, further comprising a spacer configured to divide said annular channel, the spacer extending from a first axial end of said stator housing to a second axial end of said stator housing.

E8. The drive mount according to E7, wherein said spacer mechanically couples said stator housing to said annular ring.

E9. The drive mount according to E7 or E8, wherein said annular ring comprises a cooling fluid inlet disposed adjacent a first side of said spacer, and a cooling fluid outlet disposed adjacent a second side of said spacer, the inlet and the outlet being in fluid communication with the annular channel.

E10. The drive mount according to any preceding E, wherein said housing is formed by extrusion.

E11 . The drive mount according to E10, wherein the plurality of recesses are formed from a first set of protrusions extending from the inner surface of the stator housing and a second set of protrusions extending from the inner surface of the stator housing, wherein the first set of protrusions are formed integrally with said stator housing, and the second set of protrusions are formed separately and positioned within said stator housing.

E12. The drive mount according to E11 , wherein said second set of protrusions are mechanically attached to said stator housing.

E13. The drive mount according to E11 or E12, wherein said first set of protrusions are interlaced with said second set of protrusions.

E14. The drive mount according to E13, wherein said first set of protrusions are interlaced with said second set of protrusions such that each protrusion from the first set of protrusions is adjacent a protrusion from the second set of protrusions. E15. The drive mount according to E11 to E14, wherein each of the second set of protrusions comprises a key configured to engage with a corresponding slot formed in the inner surface of the extruded stator housing to mechanically attach each protrusion thereto.

E16. The drive mount according to E11 to E14, wherein each of the second set of protrusions comprises a slot configured to engage with a corresponding key formed on the inner surface of the extruded stator housing to mechanically attach each protrusion thereto.

E17. The drive mount according to E10 to E16, wherein the stator housing is extruded as a single part.

E18. The drive mount according to E10 to 16, wherein the stator housing is formed of a plurality of circumferentially-interlocking extruded segments.

E19. The drive mount according to E10 to 18, when dependent on any of E6 to E9, wherein said annular ring is formed by extrusion.

Described above are a number of embodiments with various optional features. It should be appreciated that, with the exception of any mutually exclusive features, any combination of one or more of the optional features are possible.