DRIVE ASSEMBLY

A drive assembly for a vehicle is disclosed. The drive assembly comprises a central hub having an axis of rotation; an in-wheel electrical machine comprising a stator and a rotor; and a rim assembly comprising an inward circumferential part and an outward circumferential part, said inward circumferential part and said outward circumferential part being disposed adjacent each other along said axis of rotation, each part comprising a rim section for carrying a respective tyre, wherein the rim assembly is coupled to the hub. The in-wheel electrical machine is arranged outwardly of, and coupled to, the hub. A vehicle comprising the drive assembly is also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from United Kingdom Patent Application No. 2209889.1, filed Jul. 5, 2022, which is hereby incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to a drive assembly for a vehicle. In particular, the drive assembly is for a truck, for example a flatbed truck, a box truck, a tractor truck or the like, or for an active trailer. A vehicle comprising the drive assembly is also disclosed.

BACKGROUND

Electrical machines, including electric motors and electric generators, are widely used. However, concerns over our reliance on, and the pollution caused by, fossil fuel dependent internal combustion engines is increasing political and commercial pressures to extend the use of electrical machines to new applications, and to expand their use in existing ones. Electrical machines are increasingly being used in vehicles, such as electric cars, motorbikes, boats and aircraft. They are also used in energy generation, such as generators in wind turbines.

Another possible application of electrical machines is in trucks, such as flatbed trucks. As flatbed trucks typically have a double-wheel arrangement, their hubs differ significantly from hubs for electric cars and motorbikes. As such, in-wheel type electric machine drive assemblies for such vehicles typically require significant modification to standard hubs used for such trucks.

However, any modification to a standard hub may limit how economical integration of an in-wheel electrical machine is. As such, the inventors have appreciated the need for a drive assembly having a double rim assembly and an in-wheel electrical machine, which requires minimal or no structural modification of a standard hub, as well as minimal or no structural modification of the braking system and the axle body.

SUMMARY OF INVENTION

Embodiments described herein provide a drive assembly for a vehicle, and a vehicle comprising a drive assembly, as defined in the appended independent claims, to which reference should now be made. Preferred or advantageous features of the disclosure are set out in the dependent sub-claims.

In a first aspect, the disclosure provides a drive assembly for a vehicle. The drive assembly comprises: a central hub having an axis of rotation; an in-wheel electrical machine comprising a stator and a rotor; and a rim assembly comprising an inward circumferential part and an outward circumferential part, said inward circumferential part and said outward circumferential part being disposed adjacent each other along said axis of rotation, each part comprising a rim section for carrying a respective tyre. The rim assembly is coupled to the hub, and the in-wheel electrical machine is arranged outwardly of, and coupled to, the hub.

Advantageously, by providing a rim assembly that is coupled to the hub, and an in-wheel electrical machine which is arranged outwardly of, and coupled to, the hub, a drive assembly having an in-wheel electrical machine may be provided in which an in-wheel electrical machine may be combined with a standard hub for a double-wheel arrangement.

As both the electric machine and the rim assembly is coupled to the hub, the hub carries the load of the vehicle, while the rotor housing does not carry (any of) the load, which allows for the non-structural rotor housing to be significantly lighter. Indeed, it allows for a standard electrical machine to be used. As such, this not only allows for a lighter electrical machine to be used, but also for the drive assembly to comprise a standard hub with little or no modification.

The terms “inward” and “outward” as used herein refer to an orientation relative to a vehicle to which a drive assembly, in use, may be coupled. In particular, inward may refer to a position which is closer to such a vehicle, whereas outward may refer to a position which is further from the vehicle. The term “vehicle side” may be used instead of “inward”, and the term “road side” may be used instead of “outward”.

The term circumferential part of the rim assembly may refer to a wheel rim configured to carry a tyre.

Optionally, the rim assembly is directly coupled to the central hub. In other words, the rim assembly is not coupled to the central hub via, or together with, the electrical machine, or via any other element, but directly to hub. This may ensure that loads on the drive assembly may be transmitted directly to the hub.

Optionally, the rim assembly is directly coupled to the central hub inwardly of the electrical machine. Advantageously, this may allow for the rim assembly to be coupled to the central (standard) hub inwardly of the electrical machine, i.e. on the same side as the electrical machine is coupled to the central hub. In this manner, the standard hub may be used without any significant modification being required to the hub.

Optionally, the rim assembly comprises a substantially planar attachment section for mounting the rim assembly to the central hub. Advantageously, a substantially planar attachment section may provide a particularly suitable structure for attachment of a rim assembly.

Optionally, the rim assembly further comprises: an inward bridge section extending between the attachment section and the rim section of the inward circumferential part, the inward bridge section extending at least partially along a first direction of the rotational axis of the hub; and an outward bridge section extending between the attachment section and the rim section of the outward circumferential part, the outward bridge section extending at least partially along a second direction of the rotational axis of the hub. Such bridge sections may advantageously connect the attachment section to the inward and outward circumferential parts.

Optionally, the inward bridge section is integral with the attachment section. Advantageously, the inward bridge section being integral with the attachment section may result in a stronger rim assembly. Indeed, it may allow for the rim assembly to be coupled to the central hub in fewer steps.

Optionally, the inward bridge section is fixedly connected with the rim section of the inward circumferential part. Advantageously, this may result in a stronger rim assembly, and may allow for the rim assembly to be coupled to the central hub in fewer steps, or in a single step.

Optionally, the outward bridge section is integral with the attachment section. Advantageously, the outward bridge section being integral with the attachment section may result in a stronger rim assembly. Indeed, it may allow for the rim assembly to be coupled to the central hub in fewer steps.

Optionally, the outward bridge section is fixedly connected with the rim section of the outward circumferential part. Advantageously, this may result in a stronger rim assembly, and may allow for the rim assembly to be coupled to the central hub in fewer steps, or in a single step.

The specific shape of the outward bridge section and inward bridge section may differ depending on the application. However, at least one of the outward bridge section and inward bridge section may comprise a curved section. This may increase the strength of the bridge section, and may allow for a thinner bridge section to be used, saving weight and material.

Optionally, the inward bridge section is integral with a first, inward, portion of the attachment section, and the outward bridge section is integral with a second, outward, portion of the attachment section. By providing an attachment section having a first, inward, portion and a second, outward, portion, which are integral with the respective bridge sections, the bridge sections may be coupled to the central hub more securely, and may be coupleable to the central hub independently from one another.

Optionally, the rim assembly is coupled to the hub by a plurality of fasteners having a pitch circle diameter, the pitch circle diameter being greater than a diameter of the in-wheel electrical machine. Advantageously, such an arrangement of diameter of the pitch circle and the in-wheel electrical machine, i.e. a relative sizing of the electrical machine relative to the rim to allow for a pitch circle diameter to be larger than the electrical machine, may facilitate easier attachment of the rim assembly to the central hub.

Indeed, such a drive assembly may allow for the largest possible motor diameter whilst still providing a standardized way of mounting a rim to a standard hub. As motor volume correlates directly with peak torque of an electric motor, allowing for the largest possible motor diameter may enable the drive assembly to provide the maximum torque possible.

Optionally, each fastener is accessible inwardly of the central hub. Alternatively, each fastener is accessible outwardly of the central hub. Advantageously, if fasteners are accessible outwardly of the central hub, the rim assembly may be easily coupled to the central hub from a road side of the drive assembly. Having the fasteners accessible inwardly of the central hub may provide a more secure coupling between the central hub and the rim assembly.

Optionally, the in-wheel electrical machine is coupled to the hub independently of the rim assembly. Advantageously, this may allow the rim assembly to be detachable from the central hub without having to remove the in-wheel electrical machine, facilitating maintenance and repair of the drive assembly and potentially also of other components of a vehicle employing the drive assembly.

Optionally, a drive assembly according to any preceding claim, wherein the in-wheel electrical machine is a direct drive in-wheel electric motor. Advantageously, a direct drive in-wheel electric motor may facilitate maintenance, reduce noise during operation, and provide higher efficiency compared to an indirect electric motor.

Optionally, the drive assembly may be configured to provide a torque of at least 3,000 Nm, optionally of at least 4,000 Nm, optionally of at least 5,000 Nm, optionally up to 5,500 Nm. Such a torque may be sufficient to drive a vehicle such as a US class 6/7 truck in a 6×4 configuration. As will be appreciated, the drive assembly of the present disclosure is not limited to such torque provision, and may be adapted to provide any required torque.

Optionally, the drive assembly further comprises a gearbox. Advantageously, a gearbox allows for a torque to weight ratio of the electrical machine to be adjusted depending on a desired application, e.g. to be increased for an electric motor, or for an electric generator.

Optionally, the gearbox is a planetary gearbox. Advantageously, a planetary gearbox may be combined with an in-wheel electrical machine without significantly increase the size of the in-wheel electrical machine by attaching it to an end face of the electrical machine.

Optionally, the planetary gearbox is provided outwardly of the in-wheel electrical machine. Advantageously, in this manner, the planetary gearbox may be provided without modifying the coupling of the in-wheel electrical machine or the rim assembly to the central hub.

Optionally, the in-wheel electrical machine is an in-wheel electric motor, and the planetary gear box is configured to increase a motor speed of the electric motor relative to a wheel speed to increase a maximum torque output of the drive assembly. Advantageously, this allows for a higher torque to weight ratio to be achieved by a given electrical machine.

Optionally, the drive assembly is configured to provide a torque of at least 5,000 Nm, optionally of at least 8,000 Nm, optionally of at least 10,000 Nm, optionally of about 10,500 Nm. Such a torque may be sufficient to drive a vehicle such as a US class 8 truck using a 6×4 drive configuration. As will be appreciated, the drive assembly of the present disclosure is not limited to such torque provision, and may be adapted to provide any required torque.

Optionally, the stator is cooled by a liquid coolant. The liquid coolant optionally comprises water. The liquid coolant optionally comprises glycol. Preferably, the coolant comprises a water/glycol mixture. Advantageously, liquid cooling allows for improved removal of heat from the electrical machine, allowing for a higher current density and therefore a larger torque density.

Optionally, the drive assembly comprises tubing for providing liquid coolant to the stator through a spindle of the drive assembly attached to the central hub and a central bore of the central hub. Advantageously, such an arrangement allows for coolant to be easily supplied to the electrical machine, without modifying a standard central hub.

Optionally, the drive assembly comprises, or the drive assembly is configured to be connected to, electrical wiring routed through a, or the, spindle of the drive assembly attached to the central hub and a, or the, central bore of the central hub.

Advantageously, such an arrangement allows for required connections to and from the electrical machine of the drive assembly without modification of a standard central hub.

The electrical wiring may comprise: cables for conducting electrical power to and/or from the electrical machine, e.g. motor phase cables; and/or temperature sensors and/or wiring for temperature sensors; and/or electrical wires for an electrical machine rotational position sensor, e.g. a motor rotational position sensor; and/or electrical wires for high voltage interlock loop HVIL; and/or a grounding wire.

The drive assembly may comprise at least one temperature sensor for measuring a temperature of temperature sensitive components of the drive assembly, e.g. the electrical machine. In this way, the electrical machine may be protected from damage from overheating.

The drive assembly may comprise at least one electrical machine rotational position sensor, such as a motor rotational position sensor. Such a position sensor may allow for improved control of the electrical machine.

In a second aspect, the disclosure provides a vehicle comprising at least one drive assembly according to the first aspect.

Optionally, the vehicle is a truck. Further optionally, the vehicle is a tractor truck. Optionally, the vehicle is a flatbed truck, a box truck, or the like. In particular, the vehicle may be a US class 6/7 truck in a 6×4 configuration, or a US class 8 truck in a 6×4 configuration. Alternatively, the vehicle may be an active trailer.

It will be appreciated that features described in relation to one aspect of the present disclosure may also be applied equally to all of the other aspects of the present disclosure. Features described in relation to the first aspect of the present disclosure may be applied equally to the second aspect of the present disclosure and vice versa. For example, features of the drive assembly described in relation to the first aspects may be applied, mutatis mutandis, to the vehicle of the second aspect.

It will further be appreciated that particular combinations of the various features described and defined in any aspects of the invention may be implemented and/or supplied and/or used independently.

DETAILED DESCRIPTION

FIG.1illustrates an example system100including a drive assembly102for a truck, in particular a flatbed truck, to which two tyres104a,104bare attached.

Attached to the drive assembly102is a spindle108through which tubing112for a liquid coolant and electrical wiring110extend.

As shown inFIGS.2and3, the road-side, or outwardly, tyre104ais carried by an outward circumferential rim204aand the vehicle-side, or inwardly, tyre104bis carried by an inward circumferential rim section204b.Respective bridge sections205a,205b,attach the circumferential rim sections204a,204bto a central hub206of the drive assembly102.

The central hub206has a central cavity208. The central hub206is a standardized hub for a flatbed truck, which forms part of the drive assembly102. The spindle108extends through the central cavity208so that the tubing112and the electrical wiring110extend from a vehicle side to a road-side, or outward side, of the central hub206.

Formed as a single part with each of the respective bridge sections205a,205bare respective, substantially planar, attachment sections210a,210b.The attachment sections210a,210bare attached to the central hub206by fasteners212arranged around a rim pitch circle diameter.

Also attached to the central hub206is an electrical machine, in this case an electric motor214. The electric motor214is arranged on a road-side of, i.e. outwardly of, the central hub206. As the tubing112and the electrical wiring110extend to a road-side of the central hub206, they provide liquid coolant (a water/glycol mixture) and electrical power to the electric motor214, but also temperature sensors (and/or electrical power for temperature sensors) and electrical wires for a motor rotational position sensor, electrical wires for high voltage interlock loop HVIL, and a grounding wire for grounding the metal components of the electric motor.

The relative diameter of the electric motor214, the pitch circle diameter of the fasteners212and the circumferential rim sections204a,204bare selected such that the fasteners212can be fastened to attach the rims to the central hub206from a road-side.

The electric motor214comprises an external housing216, or rotor housing. As is clear fromFIGS.1to3, the external housing216is relatively thin. This is made possible by the load of the vehicle being carried by the central hub206, and not, as is commonly the case in the prior art, by the rotor housing216of the electric motor214.

As best seen inFIG.3, the drive assembly102further comprises a standard brake disc218, requiring no or minimal modification to function in the drive assembly102comprising the electric motor214.

FIG.4shows a further example of a drive assembly602. The drive assembly comprises an electric motor214. In contrast to the drive assembly102ofFIGS.1to3, the electric motor214of drive assembly602comprises a planetary gearbox604. The planetary gearbox604is configured to increase the torque produced by the electric motor214, which may allow a smaller electric motor to be used in the drive assembly602.

The drive assembly602also comprises a spindle108through which tubing112for a liquid coolant and electrical wiring110extend. The central hub206also has a central cavity208, and is a standardized hub for a flatbed truck, which forms part of the drive assembly602. The spindle108extends through the central cavity208so that the tubing112and the electrical wiring110extend from a vehicle side to a road-side, or outward side, of the central hub206.

In the drive assembly602, the spindle108, the tubing112and electrical wiring110extend centrally through the electric motor214so as to provide electrical power and cooling to the electric motor214but also a mechanical coupling to the planetary gearbox604, which is arranged outwardly, i.e. road-side, of the electric motor214.

The rim assembly of drive assembly602is very similar, or identical, to the rim assembly of drive assembly102.

In particular, a road-side, or outward, circumferential rim204acarries an outward tyre104a,and the vehicle-side, or inward, circumferential rim section204b(only partly shown) carries an inward tyre104b.Respective bridge sections205a,205b,attach the circumferential rim sections204a,204bto a central hub206of the drive assembly102.

As best seen inFIG.4, the bridge sections205a,205bare attached fixedly to the respective circumferential rim sections204a,204balong respective interfaces606a,606b.The fixed attachment may be by welding, or by any other suitable means.

Formed as a single part with each of the respective bridge sections205a,205bare respective, substantially planar, attachment sections210a,210b.The attachment sections210a,210bare attached to the central hub206by fasteners (not shown inFIG.4or5) arranged around a rim pitch circle diameter.

The relative diameter of the electric motor214, the pitch circle diameter of the fasteners and the circumferential rim sections204a,204bare selected such that the fasteners can be fastened to attach the rims to the central hub206from a road-side.

As best seen inFIGS.4and5, the electric motor214is attached to the central hub206by separate fasteners608(to those fasteners attaching the rim assembly to the central hub206). These fasteners608are accessible from a vehicle side of the drive assembly602. A housing or casing of the motor may comprise threaded apertures for receiving the fasteners. Alternatively, the fasteners608may comprise nuts within the electric motor214(not shown).

As discussed above in relation to the drive assembly102, the electric motor214of drive assembly602comprises an external housing216, or rotor housing. The external housing216of the drive assembly is relatively thin, which is made possible by the central hub206carrying the load of the vehicle, and not the rotor housing216.

The drive assembly602further comprises a standard brake disc218, requiring no or minimal modification to function in the drive assembly102comprising the geared electric motor214.