Lubricant delivery system

Abstract

Aspects of the present invention relate to a lubricant delivery system for an electric drive unit. The lubricant delivery system comprises a lubricant conduit assembly configured to supply lubricant to a component of the electric drive unit, wherein the lubricant conduit assembly comprises: an unrestricted supply conduit configured to supply lubricant to the lubricant conduit assembly at a predetermined supply pressure; at least one lubricant conduit defining a lubricant flow path therethrough, wherein the at least one lubricant conduit branches from the unrestricted supply conduit; wherein the at least one lubricant conduit comprises: a flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use; and a lubricant outlet located downstream of the flow restrictor, wherein the lubricant outlet is configured to direct a flow of lubricant towards the component.

Description

[0001] LUBRICANT DELIVERY SYSTEM

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a lubricant delivery system for an electric drive unit Aspects of the invention relate to a lubricant delivery system for an electric drive unit, to an electric drive unit comprising said lubricant delivery system, and to an electric vehicle comprising said electric drive unit.

[0004] BACKGROUND

[0005] Lubricant delivery systems for modern electric vehicles typically comprise one or more lubricant conduits or passageways designed to supply lubricant to components of the vehicle, for example components of a drive unit of the vehicle The intention of such lubricant delivery is to prevent components of the vehicle (such as the vehicle drive unit) from overheating and / or from wearing prematurely

[0006] The components of the vehicle drive unit may have different lubrication requirements depending, for example, on factors such as rotational speed of the component and load on the component It is therefore difficult to supply lubricant to components at optimal flow rates and velocities for efficient lubricant of all components of the vehicle drive unit.

[0007] It is an aim of the present invention to provide a solution to this issue.

[0008] SUMMARY OF THE INVENTION

[0009] Aspects and embodiments of the invention provide a lubricant delivery system, an electric drive unit, and an electric vehicle as claimed in the appended claims.

[0010] According to an aspect of the present teachings there is provided a lubricant delivery system for an electric drive unit comprising a lubricant conduit assembly configured to supply lubricant to a first component of the electric drive unit, wherein the lubricant conduit assembly comprises: at least one lubricant conduit defining a lubricant flow path therethrough, wherein the at least one lubricant conduit comprises: a flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use; and a lubricant outlet located downstream of the flow restrictor, wherein the lubricant outlet is configured to direct a flow of lubricant towards the first component.

[0011] Advantageously, during operation of a vehicle electric drive unit, the lubricant delivery system provides lubrication and cooling to components of the electric drive unit. This helps to improve the efficiency of the electric drive unit, as well as prolonging the lifespan of components of the electric drive unit, for example by reducing micro-pitting caused by the generation of heat The provision of flow restrictors in the lubricant conduit assembly helps to balance the lubricant conduit assembly, whilst providing an adequate feed of lubricant to components of the electric drive unit.

[0012] Optionally, the lubricant conduit assembly comprises an unrestricted supply conduit configured to supply lubricant to the lubricant conduit assembly at a predetermined supply pressure, and the lubricant conduit branches from the unrestricted supply conduit

[0013] Advantageously, providing an unrestricted supply line enables a high pressure (i.e. unrestricted) supply of lubricant to certain components, for example depending on the desired flow rate and velocity of lubricant supply to the component

[0014] Optionally, the flow restrictor is configured to reduce an internal diameter of the lubricant conduit from a first internal diameter to a second internal diameter

[0015] Optionally, the flow restrictor is a body having a through aperture defining the second internal diameter Optionally, the second internal diameter is in the range 0.4mm to 2mm, for example in the range 0.8mm to 1.6mm, for example in the range 1.2mm to 1.6mm.

[0016] Advantageously, reducing the internal diameter is a simple arrangement for effecting the pressure drop across the flow restrictor, thereby helping to balance the lubricant conduit assembly whilst providing adequate feed of lubricant to the components of the electric drive unit.

[0017] Advantageously, diameters within these ranges have been found to facilitate the desired pressure drop across the flow restrictor, thereby helping to balance the lubricant conduit assembly whilst providing adequate feed of lubricant to components of the electric drive unit

[0018] Optionally, the flow restrictor is formed as a separate component to the lubricant conduit, and is fitted to the lubricant conduit, in use.

[0019] Advantageously, this may help to improve ease of assembly of the lubricant conduit and restrictor, and enables restrictors of different arrangements (for example to effect different pressure drops) to be fitted to the lubricant conduit,

[0020] Optionally, the pressure drop of lubricant flowing in the lubricant conduit assembly across the flow restrictor is in the range 0.01 MPa to 0.7MPa, for example in the range 0.04MPa to 0.4MPa

[0021] Advantageously, pressure drops within these ranges have been found to help deliver the desired flow rate and velocity of lubricant out of the lubricant outlet and towards the first component. This helps to ensure the lubricant is penetrating the first component sufficiently to lubricate and cool areas of elevated pressure on the first component.

[0022] Optionally, the predetermined supply pressure is in the range 0.1 MPa 0.8MPa, for example in the range 0.2MPa to 0.6MPa.

[0023] Advantageously, pressures within these ranges have been found to deliver the desired flow rate and velocity of lubricant out of the lubricant outlet and towards components of the electric drive unit. This helps to ensure the lubricant is penetrating the component sufficiently to lubricate areas of elevated pressure on the component.

[0024] Optionally, the lubricant conduit assembly comprises a reinforcement arrangement configured to provide structural reinforcement to the lubricant conduit assembly.

[0025] Optionally, the reinforcement arrangement comprises at least one web extending from the lubricant conduit.

[0026] Advantageously, providing a reinforcement arrangement increases the structural strength of the lubricant conduit assembly, and may help to reduce vibration of the lubricant conduit as lubricant flows therethrough Webs are simple to manufacture and can be used to reinforce more than one lubricant conduit.

[0027] Optionally, the at least one lubricant conduit comprises a plurality of lubricant conduits each comprising a lubricant outlet, and each of the lubricant outlets is configured to direct a flow of lubricant towards a different component of the electric drive unit.

[0028] Optionally, at least two of the plurality of lubricant conduits each comprise a flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use

[0029] Advantageously, providing a plurality of lubricant conduits helps to provide lubrication and cooling to a plurality of components of the electric drive unit. This helps to improve the efficiency of the electric drive unit, as well as prolonging the lifespan of the components, for example by reducing micro-pitting caused by the generation of heat. Advantageously, providing more than one flow restrictor in the lubricant conduit assembly helps to provide additionally balancing to the lubricant conduit assembly, whilst providing adequate feed of lubricant to additional components of the electric drive unit Additionally, providing additional restrictors allows for a greater range of pressure values in the lubricant conduits, thereby enabling the delivery of a greater range of flow rates and velocity of lubricant delivered to the components of the electric drive unit.

[0030] Optionally, the lubricant conduit assembly comprises a return conduit configured to return lubricant from the lubricant conduit assembly to a lubricant sump of the electric drive unit.

[0031] Optionally, the lubricant conduit assembly comprises a return conduit configured to return lubricant from the lubricant conduit assembly to a pick-up conduit of the lubricant conduit assembly.

[0032] Optionally, the return conduit comprises a return flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use.

[0033] Advantageously, the provision of a lubricant sump and a return conduit enables lubricant to be recycled around the lubricant delivery system, thereby helping to reduce wastage.

[0034] Optionally, the lubricant outlet is a nozzle configured to direct the flow of lubricant towards the first component.

[0035] Optionally, the nozzle is configured to disperse the lubricant in a predetermined pattern.

[0036] Advantageously, nozzles provide precise targeting of lubricant towards components of the electric drive unit, which helps to maintain efficiency and longevity of said components. Providing nozzles may also help to reduce lubricant wastage by accurately directing lubricant. Furthermore, a diameter of the nozzle may be controlled to deliver the desired flow rate and velocity from the lubricant conduit towards the component of the electric drive unit.

[0037] Advantageously, directing the flow of lubricant in a predetermined pattern helps to target locations on the first component where elevated contact pressure is experienced, thereby reducing the effects of micro-pitting at such locations and increasing the lifespan and efficiency of the component.

[0038] Optionally, the nozzle is configured to direct the flow of lubricant towards the first component at a predetermined angle with respect to a direction of rotation of the first component.

[0039] Advantageously, directing the flow of lubricant at the predetermined angle helps to target locations on the first component where elevated contact pressure is experienced, thereby reducing the effects of micro-pitting at such locations and increasing the lifespan and efficiency of the component.

[0040] Optionally, the lubricant conduit comprises a first conduit section and a second conduit section received within the first conduit section.

[0041] Optionally, the flow restrictor is located between the first conduit section and the second conduit section.

[0042] Optionally, the second conduit section restricts movement of the flow restrictor relative to the first conduit section in at least a first direction. Advantageously, The provision of first and second conduit sections helps to improve ease of assembly of the flow restrictor within the conduit. Restricting movement of the flow restrictor in the first direction helps to prevent the flow restrictor from moving relative to the lubricant conduit when lubricant flows therethrough

[0043] Optionally, the flow restrictor is press-fitted against a shoulder of the second conduit section

[0044] Advantageously, press-fitting the flow restrictor to the second conduit section helps to improve ease of assembly of the flow restrictor to the second conduit.

[0045] Optionally, the flow restrictor is secured to the lubricant conduit using a welding process or an adhesive.

[0046] Advantageously, this arrangement helps to securely connect the flow restrictor to the lubricant conduit.

[0047] Optionally, the lubricant conduit assembly comprises a mounting arrangement configured to mount the lubricant conduit assembly to a housing of the electric drive unit.

[0048] Advantageously, providing a mounting arrangement helps to mount the lubricant conduit assembly, which is provided as a separate assembly, to the housing of the electric drive unit. As the lubricant conduit assembly is provided separately to the housing, complexity and cost of manufacture (e g casting) of the housing is reduced Additionally, heat loss in the housing is reduced, thereby improving thermal efficiency of the electric drive unit.

[0049] Providing a mounting arrangement instead of, for example, providing integral conduits which are machined into a cast housing, may help to improve ease of assembly of the lubricant conduits to the housing.

[0050] Optionally, the lubricant conduit assembly is at least partially manufactured from a thermally insulating material, for example a plastics material

[0051] Advantageously, manufacturing the lubricant conduit assembly from a thermally insulating material helps to reduce heat loss from the lubricant conduit assembly, thereby improving the thermal efficiency of the electric drive unit.

[0052] Optionally, the lubricant conduit assembly is manufactured using a moulding process.

[0053] Advantageously, moulding is a cost effective on mass production, and high levels of precision and accuracy are attainable

[0054] According to another aspect of the invention, there is provided an electric drive unit comprising: a transmission arrangement for transmitting motive power from the electric machine to one or more wheels of an electric vehicle, wherein the transmission arrangement comprises a first component; and a lubricant delivery system according to the previous aspect of the invention

[0055] Advantageously, during operation of a vehicle electric drive unit, the lubricant delivery system provides lubrication and cooling to components of the electric drive unit. This helps to improve the efficiency of the electric drive unit, as well as prolonging the lifespan of components of the electric drive unit, for example by reducing micro-pitting caused by the generation of heat The provision of flow restrictors in the lubricant conduit assembly helps to balance the lubricant conduit assembly, whilst providing an adequate feed of lubricant to components of the electric drive unit.

[0056] Optionally, the first component of the transmission is a bearing, and the lubricant outlet is configured to direct lubricant towards a contact point of the bearing.

[0057] Optionally, the contact point is an area of elevated pressure on the bearing Advantageously, during operation of the electric drive unit, considerable heat is generated in both bearings and gear interfaces, which can reduce the lifespan and efficiency of the bearing or gear interface. For bearings, contact between moving parts of the bearing (for example the balls and bearing face of a ball bearing) generates heat For gear interfaces, the meshing of teeth of adjacent gears generates heat. Providing lubricant to the bearing or gear interface therefore helps to improve the efficiency of the electric drive unit, as well as prolonging the lifespan of components of the electric drive unit, for example by reducing micro-pitting or micro-welding caused by the generation of heat

[0058] Advantageously, directing lubricant towards the contact point or the area of elevated pressure of the bearing helps to lubricate and cool the bearing at locations where the effect of heat generation (for example micro-pitting) are most exacerbated.

[0059] Optionally, the first component is a gear interface, and the gear interface is an interface of respective teeth of first and second meshing gears, and the lubricant outlet is configured to direct lubricant towards the interface of respective teeth of the first and second gears.

[0060] Advantageously, directing lubricant towards the gear interface, which is likely to be an area of elevated pressure of the gear interface, helps to lubricate and cool the gear interface at locations where the effect of heat generation are most exacerbated.

[0061] Optionally, the electric drive unit comprises a housing for containing the electric machine and / or the transmission arrangement

[0062] Advantageously, the housing provides protection to the electric machine and / or transmission arrangement, and helps to enable the recapture of lubricant therewithin, thereby reducing lubricant waste and helping to enable the recirculation of lubricant.

[0063] Optionally, an internal portion of the lubricant conduit assembly is located internal to the housing.

[0064] Optionally, an external portion of the lubricant conduit assembly is located external to the housing.

[0065] Advantageously, providing the internal and external portions provides a space efficient arrangement for supplying lubricant to components of the electric drive unit.

[0066] Optionally, the internal portion is a majority of the lubricant conduit assembly.

[0067] Optionally, the housing comprises a lubricant sump for containing lubricant, and the lubricant conduit assembly comprises a return conduit configured to return lubricant from the lubricant conduit assembly to the lubricant sump.

[0068] Advantageously, the return conduit and lubricant sump enables the recapture and recirculation of lubricant therefrom, thereby reducing lubricant waste

[0069] Optionally, the return conduit is located at least partially external to the housing.

[0070] Optionally, the lubricant outlet is a nozzle, and wherein the nozzle is located a distance from the first component in the range 1mm to 100mm, for example in the range 5mm to 50mm.

[0071] Advantageously, distances within these ranges have been found to optimise the delivery of lubricant to the first components, thereby increasing the efficiency of lubricant delivery. According to another aspect of the invention, there is provided an electric vehicle comprising: the electric drive unit according to the previous aspect; and a power source configured to supply electrical power to the electric machine of the electric drive unit.

[0072] BRIEF DESCRIPTION OF THE DRAWINGS

[0073] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0074] Figure 1 shows a vehicle in accordance with an embodiment of the invention;

[0075] Figure 2 schematically shows functional units and a control system of the vehicle;

[0076] Figure 3 shows a controller for use in the vehicle of Figure 2;

[0077] Figure 4 shows a schematic cross-sectional view of an Electric Drive Unit (EDU) assembly of the vehicle of Figures 1 and 2;

[0078] Figure 5 shows an underside view of the EDU assembly of Figure 4;

[0079] Figure 6 shows a perspective view of the EDU assembly of Figure 4;

[0080] Figure 7 shows a cross-sectional view of the EDU assembly of Figure 4;

[0081] Figure 8 shows an alternative cross-sectional view of the EDU assembly of Figure 4;

[0082] Figure 9 shows a perspective view of a lubricant conduit assembly of the EDU assembly of Figure 4;

[0083] Figure 10A shows a detailed view of a section of the lubricant conduit assembly of Figure 9; and

[0084] Figure 10B shows a detailed cross-sectional view of a section of the EDU assembly of Figure 4.

[0085] DETAILED DESCRIPTION

[0086] Figures 1 and 2 show an example of an electric vehicle (EV) 10. The electric vehicle 10 comprises a battery or battery pack 40. The battery 40 may be recharged from an external electrical source The electric vehicle 10 comprises a pair of front wheels 12 at a front axle 28 and a pair of rear wheels 14 at a rear axle 38 The vehicle has at least one electric drive unit (EDU) by which one or more of the wheels are driven In the illustrated embodiment, the vehicle comprises two electric drive units, each associated with one of the pairs of wheels. In other embodiments, the vehicle may have a dedicated EDU for each of the front wheels 12 and / or a dedicated EDU for each of the rear wheels 14.

[0087] In the illustrated embodiment, the front wheels 12 are driven by a first electric drive unit (EDU) 20. The first EDU 20 comprises a first motor 22, a front transmission 24 and power electronics 26. The rear wheels 14 are driven by a second electrical drive unit (EDU) 30. The second EDU 30 comprises a second motor 32, a rear transmission 34 and power electronics 36. The first EDU 20 and the second EDU 30 each receive a DC supply from battery 40 The first EDU 20 can be called a first propulsion unit and the second EDU 30 can be called a second propulsion unit. As used herein, the term “transmission” may refer to a device with a plurality of gears through which torque can be transmitted from the drive unit to one or more of the wheels. For example, this may refer to a differential, transaxle, and / or a gearbox.

[0088] The electric vehicle 10 has a control system with a controller 50 which controls operation of the first EDU 20 and the second EDU 30. In operation, the controller 50 controls the power output of each of the EDUs 20, 30 to supply torque to the wheels 12, 14. Power electronics 26 comprise an inverter which converts the DC supply from battery 40 to an AC supply to drive the first motor 22 The first motor 22 drives the front transmission 24 which, in turn, drives the front axle 28 to apply torque to the front wheels 12 Power electronics 36 comprise an inverter which converts the DC supply from battery 40 to an AC supply to drive the second motor 32. The second motor 32 drives the rear transmission 34 which, in turn, drives the rear axle 38 to apply torque to the rear wheels 14. One or both of the front and rear axles 28, 38 may be a continuous shaft extending through their respective EDU, or a pair of half shafts which extend from their respective EDU

[0089] Figure 3 schematically shows the control system. The control system comprises one controller 50, although it will be appreciated that this is merely illustrative. The controller 50 comprises at least one processor 56 which may be any type of processor for executing instructions to control the operation of the system. The processor 56 is electrically connected to other components of the controller via one or more buses 57. Processor-executable instructions 48 may be provided using any data storage device or computer-readable media, such as memory 58 The processor-executable instructions 48 comprise instructions for implementing the functionality of the described methods The storage / memory 58 is of any suitable type such as non-volatile memory, a magnetic or optical storage device. The processor 56 is configured to access the memory 58 and execute the stored instructions 48. Memory 58, or a separate memory / storage stores data 60 used by the processor 56. Data 60 may comprise data which defines a plurality of operating points of the first motor 22. Instructions 48 may comprise rules for selecting between plurality of operating points of the first motor 22. The controller 50 comprises an input interface 54. The input interface 54 is configured to receive one or more input signals 53 (e.g., a demand for acceleration or a demand for speed). The controller 50 comprises an output interface 55. The output interface 55 is configured to output outputs, such as the control signal 51 to control the first motor 22 (sent to power electronics 26) and the control signal 52 to control the second motor 32 (sent to power electronics 36). The controller 50 is configured to use one or more of the input signals 53 and stored data 60, to generate output signals 51, 52.

[0090] Optionally, the controller 50 may operate the vehicle in the following ways:

[0091] (i) Rear-wheel drive (RWD). Torque is only supplied to the rear wheels 14 by operating the second motor 32 to drive the rear wheels 14. The front wheels 12 are not driven by the first motor 22;

[0092] (ii) All-wheel drive (AWD). Torque is supplied to the rear wheels 14 and to the front wheels 12 by operating the second motor 32 to drive the rear wheels 14 and operating the first motor 22 to drive the front wheels 12;

[0093] (Hi) Front-wheel drive (FWD). Torque is only supplied to the front wheels 12 by operating the first motor 22 to drive the front wheels 12. The rear wheels 14 are not driven by the second motor 32.

[0094] In some vehicles, the controller 50 may only operate according to options (i) and (ii), and may not operate according to option (iii).

[0095] In other embodiments, the electric vehicle may include only one EDU 20, 30. For example, the second EDU 30 may be omitted in embodiments where the electric vehicle is a “front-wheel drive" vehicle, or the first EDU 20 may be omitted in embodiments where the electric vehicle is a “rear-wheel drive” vehicle. In further embodiments, one or more of the wheels may be driven individually by a dedicated EDU. For example, the front wheels 12 may each be connected to one of a pair of front EDUs. Referring now to Figures 4 and 5, an EDU assembly is indicated at 100. The EDU assembly 100 includes a motor 102 (shown schematically in Figure 4), a transmission 112 (shown schematically in Figure 4), and a housing 150 for the motor 102 and the transmission 112 It will be understood that the EDU assembly 100 illustrated in Figures 4 and 5 could be, or form part of, the first EDU 20 and / or the second EDU 30 illustrated schematically in Figure 2, along with the additional power electronics 26, 36 described above (not illustrated in the EDU assembly 100 of Figures 4 and 5).

[0096] The motor 102 may be an induction motor (IM) An induction motor can also be called an induction machine, as it is capable of operating as a motor and as a generator. Alternatively, the motor 102 may be a permanent magnet (PM) synchronous motor. In either case, the motor 102 includes a rotor 104 and a stator 106 with electrical windings 108. The motor 102 is operated by suppling an AC supply to the stator windings 108 which causes movement of the rotor 104 about a rotational axis R IM and PM motors are known and will therefore not be described in more detail In some embodiments, the motor 102 is of a different kind, such as a DC motor, a universal motor, or a non-electrical motor such as a hydraulic motor.

[0097] The rotor 104 is coupled to a motor output shaft 110. In other words, the rotor 104 and output shaft 110 are configured for co-rotation about the rotational axis R. In this way, as the rotor 104 is rotated by the AC supply to the stator windings 108, the output shaft 110 is also rotated. The output shaft 110 is supported for rotation relative to the housing 150 by an output shaft bearing arrangement 116 which, in this embodiment, includes a first bearing 116A (shown schematically in Figure 4) on a first side of the output shaft 110 and a second bearing 116B (shown schematically in Figure 4) on a second side of the output shaft 110. The first and second bearings 116A, 116B may be ball bearings, roller bearings or any other suitable bearing.

[0098] The transmission 112 is responsible for transmitting power from the output shaft 110 of the motor 102 to the front or rear wheels 12, 14 of the electric vehicle 10. Optionally, the transmission 112 includes a differential 118 (shown schematically in Figure 4) which allows half shafts (not shown in Figure 4 or 5) of the respective axle 28, 38 to be rotated at different speeds while receiving power from the motor 102. In some embodiments, the transmission 112 may comprise a gearbox between the output shaft 110 of the motor 102 and the differential 118. The differential 118 may be of any suitable configuration. The differential 118 may include one or more components which are supported for rotation relative to the housing 150 by a differential bearing arrangement (not shown) including one or more bearings

[0099] Although not illustrated in Figures 4 and 5, the half shafts of the respective axle 28, 38 may be coupled to the differential 118 via any suitable means (e.g., by engaging external splines on the half shafts with internal splines on a component of the differential 118) The half shafts may be supported for rotation relative to the housing by one or more half shaft bearings 130, which may be ball bearings, roller bearings or any other suitable bearing

[0100] The illustrated EDU assembly 100 includes a lubricant recirculation system 200, which supplies lubricant to one or more rotating components of the EDU (e.g., motor 110, bearings 116 A, 116B, 130, and / or the differential 118 outlined above). The lubricant, such as oil, may both lubricate and cool those rotating components. The lubricant recirculation system 200 includes a sump 152 and a lubricant pump 202 which supplies lubricant along a flow path between the sump 152 and the interior of the housing 150. The flow path is at least in part defined by one or more conduits. The lubricant which is supplied into the housing 150 is then drained into the sump 152 at a lower end of the housing 150. A lubricant pick-up pipe 154 is provided adjacent to or in the sump 152. The lubricant pick-up pipe 154 has a lubricant inlet aperture 156 through which lubricant may be drawn into the pick-up pipe 154 by means of the lubricant pump 202. In this way, lubricant is recirculated by the lubricant pump 202 through the housing 150. The lubricant recirculation system 200 may also include a lubricant filter 204. In the illustrated embodiment, the lubricant filter 204 is located along the flow path downstream of the lubricant pump 202. In the illustrated embodiment, the housing 150 has a first portion 150A which houses the motor 102, and a second portion 150B which houses the transmission 112. In the illustrated embodiment, the first and second housing portions 150A, 150B are discrete components which are coupled together (e g , via a bolting arrangement) The housing 150 may also include a cover 150C (shown schematically in Figure 4) which closes an end of the first housing portion 150A opposite to the second housing portion 150B. The cover 150C may be a discrete component which is coupled to the first housing portion 150A (e.g. via a bolting arrangement), or may instead be integrally formed with the first housing portion 150A. In alternative embodiments, any other suitable housing configuration may be used

[0101] The housing 150 may have one or more mounting features 132 for mounting the EDU assembly 100 to a sub-frame of the electric vehicle 10 and / or for reacting torsional forces generated by the EDU assembly.

[0102] The illustrated EDU assembly 100 also includes seal assemblies 300 at opposite ends of the housing 150, for sealing against the half shafts of the respective axle 28, 38. Such seal assemblies 300 provide a sealed system inside the housing 150 and thereby inhibit ingress of contaminants (e.g., dirt,, debris, water, etc.) inside the housing 150.

[0103] Figure 6 shows a perspective view of the EDU assembly 100 of Figures 1 to 5 including the lubrication recirculation system 200, which may be referred to hereinafter as a lubricant delivery system 200. The lubricant delivery system 200 includes a lubricant conduit assembly 206 configured to supply lubricant to a first component of the EDU assembly 100

[0104] It shall be appreciated that the first component may be a bearing or a gear interface of the EDU assembly 100. During operation of the EDU assembly 100, considerable heat is generated in both bearings and gear interfaces, which can reduce the lifespan and efficiency of the bearing or gear interface. For bearings, contact between moving parts of the bearing generate heat. For gear interfaces, the meshing of teeth of adjacent gears generates considerable heat. Providing lubricant to the bearing or gear interface therefore helps to improve the efficiency of the EDU assembly 100, as well as prolonging the lifespan of components of the EDU assembly 100, for example by reducing micro-pitting or micro-welding caused by high force metal to metal contact.

[0105] In the EDU assembly 100 of Figure 6, the lubrication conduit assembly 206 is configured to supply lubricant to a plurality of different components (i.e. a first, second, third component etc). The lubricant conduit assembly 206 may be configured to supply lubricant to any one of, or any combination of: the first bearing 116A of the output shaft bearing arrangement 116, the second bearing 116B of the output shaft bearing arrangement 116, the first bearing 128A of the carrier bearing arrangement 128, the second bearing 128B of the carrier bearing arrangement 128, the half shaft bearings 130, an interface between spider gears 122 and a respective side gear 124, an interface between the side gears 124 and splines on the half shafts. In addition or alternatively, the lubricant conduit assembly 206 may be configured to supply lubricant to any alternative bearings not shown in the cross-section of Figure 4, for example any of the bearings associated with the first or second motors 22, 32. The different components and / or systems have different lubrication requirements dependent on, for example, the speed at which the component is moving or rotating, how the component interacts with and / or engages with other components, where the component is situated within the EDU assembly 100, and a radius of the gear or bearing. It is therefore advantageous to supply lubricant to various components at different pressures to achieve a desired flow rate and velocity of lubricant.

[0106] When the component is a bearing, for example any of bearings 116A, 116B, 128A, 128B, 130, the lubricant conduit assembly 206 is configured to direct lubricant towards a contact point of the bearing. The contact point is an area of elevated pressure of the bearing, for example an area of maximum pressure of the bearing. Directing lubricant towards the contact point or the area of elevated pressure of the bearing helps to lubricate and cool the bearing at locations where the effect of heat generation (for example micro-pitting and micro-welding) are most exacerbated. In embodiments where the bearings 116A, 116B, 128A, 128B, 130 are ball bearings or roller bearings, the contact point may be between the ball or roller bearings and a respective inner race of the bearing 116A, 116B, 128A, 128B, 130. A number of factors effect where on the bearing the location of elevated or maximum pressure is located, for example bearing design, magnitude and direction of a load applied, rotational speed of the ball or roller bearings, bearing alignment and gravity. In particular, heavy loads, bearing misalignment, insufficient lubrication and / or excessive rotational speeds can lead to localised areas of elevated pressure, potentially leading to premature wear of the bearing at these locations. It is therefore advantageous for lubricant to be directed to such areas to prolong the lifespan of the bearing

[0107] When the component is a gear interface, for example an interface between spider gears 122 and a respective side gear 124 or an interface between the side gears 124 and splines on the half shafts, the lubricant conduit assembly 206 is configured to direct lubricant towards the interface of respective teeth of the meshing gears This area is known as the contact point, or contact patch. In addition or alternatively, the lubricant conduit assembly 206 may be configured to supply lubricant to any alternative gear interfaces / meshes not shown in the cross-section of Figure 4, for example first or second gear stages of the front or rear transmission 24, 34. These contact points bear a majority of the load and experience the highest pressure of the gears The pressure is concentrated at these contact points due to the forces involved in transmitting torque and power between the meshing gears. The exact location of the maximum pressure experienced by the gears depends on factors such as design ofthe gear teeth, magnitude of the transmitted load, lubrication, gear material and accuracy of gear manufacture (which may lead to misalignment).

[0108] For both bearings and gear interfaces, due to the significant rotational speeds, it is desirable to provide lubricant at particular velocities so that the lubricant can penetrate through to the contact points described above. Accordingly, flow rate, velocity and direction of lubricant delivered to the component are all important factors when optimising lubricant delivery.

[0109] The lubricant conduit assembly 206 is at least partially manufactured using a moulding process, for example using an injection moulding process. Moulding is cost effective on mass production, and high levels of precision and accuracy are attainable. Furthermore, moulding is compatible with thermally insulating materials. It shall be appreciated that the lubricant conduit assembly 206 may be formed from a number of moulded components which are assembled together to form the lubricant conduit assembly 206, as will be described in more detail below The lubricant conduit assembly 206 is at least partially manufactured from a thermally insulating material, for example a plastics material. Manufacturing the lubricant conduit assembly 206 from a thermally insulating material helps to reduce heat loss from the lubricant conduit assembly 206, thereby improving the thermal efficiency of the EDU assembly 100 This is particularly true in comparison to cast channels which are provided integrally with the housing, whereby considerable heat is lost through the channels and to the housing ofthe EDU assembly. The lubricant conduit assembly 206 may be manufactured from more than one thermally insulating material, for example more than one plastics material. By way of example, particular sections of the lubricant conduit assembly 206 may be manufactured from a plastics material with a higher structural strength, thereby increasing the structural strength of the lubricant conduit assembly 206 at certain locations.

[0110] The lubricant conduit assembly 206 is provided as a separate sub-assembly to the housing 70, and is mounted to the housing 70. The lubricant conduit assembly 206 includes a mounting arrangement 207a, 207b configured to mount the lubricant conduit assembly 206 to the housing 70 and the EDU assembly 100. As the lubricant conduit assembly 206 is provided separately to the housing 70, complexity and manufacture (e g. casting) ofthe housing 70 is reduced. Additionally, heat loss in the housing 70 is reduced, thereby improving the thermal efficiency of the EDU assembly.

[0111] The lubricant conduit assembly 206 may be located both internal and external to the housing 70. As illustrated in Figures 7 and 8, an internal portion 206a of the lubricant conduit assembly 206 is located internal to the housing 70. The internal portion 206a may be a majority of the lubricant conduit assembly 206. As illustrated in Figure 6, an external portion 206b of the lubricant conduit assembly 206 may be located external to the housing 70. The external portion 206b may be a minority of the lubricant conduit assembly 206 The mounting arrangement 207a, 207b includes both external and internal mounting formations 207a, 207b. The internal mounting formations 207a are configured to mount the lubricant conduit assembly to internal components of the housing 70.

[0112] As shown in Figures 7 to 9, the internal mounting formations 207a are projections extending from the lubricant conduit assembly 206. Each of the projections includes a bore for receiving a fastener. The fastener extends through the bore, and through a corresponding bore in the internal component of the housing 70 to secure the lubricant conduit assembly 206 to the internal component of the housing 70. In the embodiment of Figures 7 and 8 two internal mounting formations 207a are illustrated, however it shall be appreciated that any suitable number of internal mounting formations 207a may be used to mount the internal portion 206a of the lubricant conduit assembly 206 to the housing 70. In the embodiment shown in Figure 6, the external mounting formations 207b are of substantially the same configuration to the internal mounting formations 207a, and include projections extending from the lubricant conduit assembly 206. Each of the projections includes a bore for receiving a fastener. It shall be appreciated that any suitable number of external mounting formations 207b may be used to mount the external portion 206b of the lubricant conduit assembly 206 to the housing 70

[0113] The lubricant pump 202 is arranged to deliver lubricant at a predetermined supply pressure to the lubricant conduit assembly 206. That is to say that lubricant is supplied from an outlet of the lubricant pump 202 to the lubricant conduit assembly 206 at a pressure referred to as the supply pressure.

[0114] The lubricant conduit assembly 206 includes an unrestricted supply conduit 208, at least one lubricant conduit 210 defining a lubricant flow path therethrough, and a return conduit 212 configured to return lubricant from the lubricant conduit assembly 210 to the lubricant sump 152 or to a pick-up pipe of the lubricant conduit assembly. Each of the supply conduit 208, the at least one lubricant conduit 210 and the return conduit 212 include a lubricant outlet 214 configured to direct a flow of lubricant towards a lubricant delivery location, for example a component of the EDU assembly 100, or towards the lubricant sump 152.

[0115] In addition to receiving lubricant from the lubricant pump 202, the supply conduit 208 supplies lubricant to the lubricant outlet 214 at a first pressure substantially equal to the supply pressure (i.e. a high pressure supply of lubricant). That is to say that unrestricted flow of lubricant is supplied from the lubricant pump 202 to the lubricant outlet 214 by the supply conduit 208. Therefore, any difference between the supply pressure and the first pressure is due to system pressure losses, such as frictional losses along the walls of the supply conduit 208 and / or dynamic losses in fittings with the supply conduit 208. A substantially equal supply pressure and first pressure may here be defined as the first pressure being within 5%, for example within 2%, further for example within 1 % of the supply pressure. By way of example, the supply pressure may be in the range 0.1 MPa to 0.8MPa, for example in the range 0.2MPa to 0.6MPa. Examples of components which may receive lubricant at the first pressure may be any of the high speed bearings or gears. The supply conduit 208 may include more than one lubricant outlets 214 so that lubricant is supplied at the first pressure to more than one component. By way of example, the supply conduit 208 may include two or more lubricant outlets 214, for example five lubricant outlets 214.

[0116] The lubricant outlet 214 of any of the lubricant conduits 210, return conduit 212 and / or supply conduit 208 may be an aperture or a nozzle 214 It shall be appreciated that lubricant exiting the lubricant distribution system 200 may still be contained within the overall lubricant distribution system 200, for example lubricant may be dispersed into the housing 70 where it is drained into the sump 152, as described previously. It is advantageous to provide a nozzle 214 designed to disperse lubricant in a predetermined pattern dependent on the lubrication requirements of the component adjacent the nozzle 214 Byway of example, the predetermined pattern may be a jet ora spray pattern. The nozzle 214 may be designed to disperse a predetermined flow rate of lubricant towards the component, and / or to disperse lubricant towards a predetermined location or area of the component These design features may be determined by the shape of the nozzle 214, such as for example the diameter of a bore through the nozzle 214 and / or the shape of an aperture in the nozzle 214 through which lubricant exits the nozzle 214. These design features result in nozzles 214, and hence lubricant delivery locations, requiring lubricant supplied at a predetermined pressure in order to deliver the desired flow rates and velocities of lubricant exiting the nozzle 214, where the predetermined pressure may vary between different nozzles 214.

[0117] The nozzles 214 may be configured to direct the flow of lubricant towards the first component at a predetermined angle with respect to a direction of rotation of the first component. This helps to target locations on the first component elevated contact pressure is experienced, thereby reducing the likelihood of premature wear in these locations. In addition, the nozzle 214 (or more generally lubricant outlet 214), may be located a predetermined distance from the first component By way of example, the distance may be in the range 1 mm to 100mm, for example in the range 5mm to 50mm. The distance between the lubricant outlet 214 and the first component may depend on the rotational speed of the first component. Distances within the above ranges have been found to supply lubricant at a desirable velocity, whilst providing clearance from rotating parts.

[0118] As illustrated in Figure 9, the type of nozzle 214 may vary depending on the component at which the nozzle 214 directs lubricant. Figure 9 shows the lubricant conduit assembly 206 in use, whereby lubricant is flowing through the lubricant conduit assembly 206 and the nozzles 214 are directing lubricant towards components, for example in a lubricant jet. In Figure 9, a first nozzle 214a is provided for directing lubricant towards bearings, and a second nozzle 214b is provided for directing lubricant towards gear interfaces. It shall be appreciated that in alternative embodiments, the same type of nozzle 214a, 214b may be used for all applications. Either or both of the nozzles 214a, 214b may include more than one nozzle outlet 215, thereby enabling each nozzle 214 to direct lubricant to more than one location, or to more than one component. Some of the nozzles 214 may include only one nozzle outlet 215, and some nozzles 214 may include more than one nozzle outlet 215.

[0119] It shall be appreciated that the at least one conduit includes a plurality of lubricant conduits 210 each including the lubricant outlet 214, as described above, and a flow restrictor 216 configured to effect a pressure drop across the flow restrictor 216 in a lubricant flowing in the lubricant conduit assembly 208. This enables the lubricant conduit assembly 206 to supply lubricant to a variety of components of the EDU assembly 100 via the lubricant outlets 214 The flow restrictor 216 is illustrated in Figures 8, 10A and 10B. It shall be appreciated that the return conduit 212, illustrated in Figure 10B, may be considered one of the plurality of lubricant conduits 210, as will be described in more detail below It shall be appreciated that in some embodiments, only one lubricant conduit 210 may be provided. In the embodiment of Figures 6 to 10B, the plurality of lubricant conduits 210 include at least three lubricant conduits 210, for example six lubricant conduits 210. In some embodiments, each of the plurality of lubricant conduits 210 may branch off from the supply conduit 208. Alternatively, one or more of the plurality of lubricant conduits 210 may branch off from the supply conduit 208, and the other of the lubricant conduits 210 may branch off from other lubricant conduits 210 There may be one flow restrictor 216 located in each branch, or more than one flow restrictor 216 located in each branch such that the pressure drop is effected more than once along the respective branch. The flow restrictor 216 is provided as a separate component to the lubricant conduit 210, and is fitted to the lubricant conduit 210, as will be described in more detail below. In alternative embodiments, the flow restrictor 216 may be formed integrally with the lubricant conduit.

[0120] The lubricant outlet 214 is located downstream of the flow restrictor 216 This enables lubricant of reduced pressure outlet from the flow restrictor 216 to be delivered to the lubricant outlet 214. In particular, the lubricant outlet 214 may be located at least 8mm downstream of the flow restrictor 216, for example at least 10mm downstream of the flow restrictor 216. This helps to facilitate laminar flow of lubricant supplied to the nozzle 214. The pressure drop of lubricant flowing in the lubricant conduit assembly 206 across the flow restrictor 216 may be in the range 0 01 MPa to 0.7Mpa, for example in the range 0.04MPa to 0 4MPa. The pressure drop may be the same across all of the flow restrictors 216, or different pressures drops may be possible over different flow restrictors 216 This helps to increase the range of possible pressures at which lubricant may be supplied to the lubricant outlets 214, thereby increasing the variety of possible flow rates and velocities at which lubricant may exit the lubricant outlets 214.

[0121] The flow restrictor 216 will be described in detail in relation to Figures 10A and 10B The flow restrictor is formed as a separate component to the lubricant conduit assembly 206, and is assembled thereto. The flow restrictor 216 may be formed from a thermally insulation material, for example a plastics material. The flow restrictor 216 may include a body defining an aperture therethrough, as illustrated in Figure 10A. In order to effect the pressure drop therethrough, the flow restrictor 216 is configured to reduce an internal diameter of the lubricant conduit 210 from a first internal diameter to a second internal diameter, as illustrated in Figures 10A and 10B. The first internal diameter is a diameter of the lubricant conduit 210 immediately upstream of the flow restrictor 216. The second internal diameter is a diameter of an aperture extending through the restrictor 216. The second internal diameter may be in the range 0.4mm to 2mm, for example in the range 0.8mm to 1.6mm, for example in the range 1.2mm to 1 6mm. It shall be appreciated that after lubricant has flowed through the flow restrictor 216, the diameter of the lubricant conduit 210 increases to a third diameter The third internal diameter is equal to an internal diameter of the lubricant conduit 210 immediately upstream of the flow restrictor 216. The third internal diameter may be equal to the first internal diameter, as illustrated in Figure 10A, or the third internal diameter may be greater than or less than the first internal diameter.

[0122] It shall be appreciated that the internal diameter and / or an axial length of the restrictor 216 may be varied in order to increase or decrease the pressure drop thereacross. As such, the restrictor 216 is a simple component capable of delivering a range of pressures to the lubricant outlets 214 through simple modifications to dimensions of the flow restrictor 216.

[0123] The flow of lubricant through the supply conduit 208 and through lubricant conduits 210 to the lubricant outlets 214 will be described with specific reference to Figures 7 and 8, which shows a portion of the lubricant conduit assembly 206 The supply conduit 208 does not include a flow restrictor 216, as described above. As such, the lubricant flows through the supply conduit 208 and out of the nozzle 214 towards the component, which is the first bearing 128A and / or the second bearing 116B on the first side of the carrier 120 in the embodiment of Figures 7 and 8. Some of the lubricant (i.e. the lubricant which is not directed through the nozzle 214) continues to flow along the supply conduit 208, and splits off into two branches. The first branch does not include the flow restrictor 216, and therefore forms a continuation of the supply conduit 208 The supply conduit 208 includes a second nozzle 214 located downstream of the first nozzle 214, which directs lubricant at the first pressure (or a pressure substantially equal to the supply pressure, as described above) towards the first and second gear stages (not shown) of the front or rear transmission 24, 34.. The second branch is defined by lubricant conduit 210 including flow restrictor 216. The lubricant flows from the supply conduit 208 and into the second branch, through the restrictor 216 and to the nozzle 214 at the predetermined pressure (lower than the supply pressure) towards the first bearing 128A and / or the second bearing 116B.

[0124] At least one of the plurality of lubricant conduits 210 (including the supply conduit 208) may include at least a first conduit section 208a, 210a and a second conduit section 208b, 210b, as illustrated in Figures 7 and 8. The second conduit section 210a is received within the first conduit section 210a. The second conduit section 210b may be located upstream or downstream of the first conduit section 210a, as illustrated in Figure 7 and 8.

[0125] In the embodiment of Figures 7 and 8, three first conduit sections 208a, 210a are formed integrally, and are each fitted to a respective second conduit section 208b, 210b to form the supply conduit 208 and lubricant conduit 210. Each of the first conduit sections 210a extend at an angle with respect to the other first conduit sections 210a so as to enable lubricant to flow in different directions. Each of the first conduit sections 208a, 210a includes a stepped cross-sectional profile defining a shoulder 218 The second conduit sections 208b of the supply conduit 208 are secured to the first conduits sections 208a of the supply conduit 208, and each abut against the respective shoulder 218 such that movement of the first conduit section 208a with respect to the second conduit section 208b is restricted. The supply conduit 208 in the portion shown in Figures 7 and 8 is therefore formed from an upstream second conduit sections 208b, the first conduit section 208a and a downstream conduit section 208b

[0126] The flow restrictor 216 is located between the first conduit section 210a and the second conduit section 210b which form the first lubricant conduit 210. The second conduit section 210b restricts movement of the flow restrictor 216 relative to the first conduit section 210a in a first axial direction, and the shoulder 218 restricts movement of the flow restrictor 216 relative to the first conduit section 210a in a second axial direction. As such, the flow restrictor 216 is restricted in opposing axial directions. The provision of first and second conduit sections 210a, 210b helps to improve ease of assembly of the flow restrictor 216 within the lubricant conduit 210 Restricting movement of the flow restrictor 216 in both axial directions helps to prevent the flow restrictor 216 from moving, for example from coming dislodged, relative to the lubricant conduit when lubricant flows therethrough. In embodiments where the flow restrictor 216 is present, it is therefore the flow restrictor 216 which abuts against the shoulder 218 of the first conduit section 210a, as opposed to the second conduit section 210b. In particular, the flow restrictor 216 is press-fitted against the shoulder 218 of the second conduit section 210b The flow restrictor 216 is therefore located axially between the shoulder 218 of the first conduit section 210a and the second conduit section 210b.

[0127] The lubricant conduit assembly 206 includes a reinforcement arrangement 220a, 220b configured to provide reinforcement to the lubricant conduit assembly 206. As illustrated in Figures 7 and 8, the reinforcement arrangement 220a, 220b may include webbed sections 220a, 220b extending between the first sections 208a of the supply conduit 208 and the first section 210a of the first lubricant conduit 210. In particular, a first webbed second 220a extends between the first conduit sections 208a of the supply conduit 208, and a second webbed section 220b extends between the first conduit section 208a of the supply conduit 208 and the first conduit section 210a of the first lubricant conduit 210. It shall be appreciated that although not shown, the reinforcement arrangement 220 may include webbed sections located at each branch of the lubricant conduit assembly 206 to provide structural reinforcement thereto. In addition or alternatively, the lubricant conduit assembly 206 may include sections of increased conduit wall thickness, and / or reinforcing ribs.

[0128] The return conduit 212 may be configured to return lubricant not supplied to the components of the EDU assembly 100 to the lubricant sump 152 and / or to a pick-up conduit of the lubricant conduit assembly 206. Put another way, the return conduit 212 may be configured to supply overflow or excess lubricant from the lubricant conduit assembly 206 to the lubricant sump 152. As such, the return conduit 212 may branch off from the unrestricted supply conduit 208, meaning that the pressure of lubricant flowing through the return conduit 212 is substantially equal to the first pressure. The lubricant may be returned to the lubricant sump 152 via the lubricant outlet of the return conduit 212, or the lubricant outlet of the return conduit 212 may be omitted and the lubricant may be delivered to the lubricant sump 152 by an aperture or orifice. The housing 70 may include additional channels or drainage ports for returning lubricant supplied to components of the EDU assembly 100 to the lubricant sump 152. The lubricant supplied to the components of the EDU assembly 100 may be caught within the housing 70, and drain off from the housing 70 to the lubricant sump 152 via the channels or drainage ports.

[0129] The flow restrictor 216 may be secured to the lubricant conduit 210 using a welding process or an adhesive, or the flow restrictor 216 may be mechanically located into the lubricant conduit 210 by a threaded connection, as illustrated in Figure 10B. Figure 10B shows the flow restrictor 216 of the return conduit 212. This flow restrictor 216 lowers the pressure of lubricant returning to the lubricant sump 152 This is particularly advantageous in embodiments where the return conduit 212 branches off from the unrestricted supply conduit 208 and lubricant pressure is substantially equal to the supply pressure In this embodiment, the first conduit section 212a is connected to the second conduit section 212b by a conduit connector 224. The second conduit section 212b is integral with the housing 70 (for example the second conduit 212b may be machined into the housing 70). The flow restrictor 216 is secured to the integral second conduit section 212b using adhesive or a welding process, or may be screwed into the second conduit section 212b. As such, the flow restrictor 216 may be secured to the second conduit section 212b priorto mounting of the lubricant conduit assembly 206 to the housing 70. In particular, the flow restrictor 216 abuts against a shoulder 218 of the second conduit assembly. The flow restrictor 216 is therefore located between the connector member 224 and the second conduit section 212b The first conduit section 212a extends from the connector member 224 This arrangement helps to enable access of a tool, for example an Allan key, to assemble / disassemble the first section 212a and / or the conduit connector 224 from the second conduit section 212b.

[0130] It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application. It should also be noted that whilst the appended claims set out particular combinations of features described above, the scope of the present disclosure is not limited to the particular combinations hereafter claimed, but instead extends to encompass any combination of features herein disclosed.

Claims

CLAIMS1 A lubricant delivery system for an electric drive unit, the lubricant delivery system comprising: a lubricant conduit assembly configured to supply lubricant to a first component of the electric drive unit, wherein the lubricant conduit assembly comprises: an unrestricted supply conduit configured to supply lubricant to the lubricant conduit assembly at a predetermined supply pressure; at least one lubricant conduit defining a lubricant flow path therethrough, wherein the at least one lubricant conduit branches from the unrestricted supply conduit; wherein the at least one lubricant conduit comprises: a flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use; and a lubricant outlet located downstream of the flow restrictor, wherein the lubricant outlet is configured to direct a flow of lubricant towards the first component.

2. The lubricant delivery system according to claim 1 , wherein the flow restrictor is configured to reduce an internal diameter of the lubricant conduit from a first internal diameter to a second internal diameter, and wherein the flow restrictor is a body having a through aperture defining the second internal diameter, optionally wherein the second internal diameter is in the range 0 4mm to 2mm, for example in the range 0 8mm to 1.6mm, for example in the range 1 ,2mm to 1 ,6mm3. The lubricant delivery system according to claim 1 or claim 2, wherein the flow restrictor is formed as a separate component to the lubricant conduit, and is fitted to the lubricant conduit, in use.

4. The lubricant delivery system according to any preceding claim, wherein the lubricant conduit assembly comprises a reinforcement arrangement configured to provide structural reinforcement to the lubricant conduit assembly.

5. The lubricant delivery system according to any preceding claim, wherein the at least one lubricant conduit comprises a plurality of lubricant conduits each comprising a lubricant outlet, and wherein each of the lubricant outlets is configured to direct a flow of lubricant towards a different component or location of the electric drive unit, optionally wherein at least two of the plurality of lubricant conduits each comprise a flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use6. The lubricant delivery system according to claim 5, wherein the plurality of lubricant conduits comprises a return conduit configured to return lubricant from the lubricant conduit assembly to a lubricant sump of the electric drive unit, optionally wherein the return conduit comprises a return flow restrictor configured to effect a pressure drop across the flow restrictor in a lubricant flowing in the lubricant conduit assembly, in use.7 The lubricant delivery system according to any preceding claim, wherein the lubricant outlet is a nozzle configured to direct the flow of lubricant towards the first component, optionally wherein the nozzle is configured to disperse the lubricant in a predetermined pattern.8 The lubricant delivery system according to any preceding claim, wherein the lubricant conduit comprises a first conduit section and a second conduit section received within the first conduit section, wherein the flow restrictor is located between the first conduit section and the second conduit section, and wherein the second conduit section restricts movement of the flow restrictor relative to the first conduit section in at least a first direction.

9. The lubricant delivery system according to claim 8, wherein the flow restrictor is press-fitted against a shoulder of the second conduit section10. The lubricant delivery system according to any preceding claim, wherein the lubricant conduit assembly is at least partially manufactured from a thermally insulating material, for example a plastics material11. An electric drive unit comprising: an electric machine; a transmission arrangement for transmitting motive power from the electric machine to one or more wheels of an electric vehicle, wherein the transmission arrangement comprises a first component; and a lubricant delivery system according to any preceding claim.

12. The electric drive unit according to claim 11 , wherein the first component of the transmission is a bearing, and wherein the lubricant outlet is configured to direct lubricant towards a contact point of the bearing, optionally wherein the contact point is an area of elevated pressure on the bearing.

13. The electric drive unit according to claim 11 , wherein the first component is a gear interface, and wherein the gear interface is an interface of respective teeth of first and second meshing gears, and wherein the lubricant outlet is configured to direct lubricant towards the interface of respective teeth of the first and second gears14. The electric drive unit according to any one of claim 11 to claim 13, wherein the electric drive unit comprises a housing for containing the electric machine and / or the transmission arrangement, and wherein an internal portion of the lubricant conduit assembly is located internal to the housing, and wherein an external portion of the lubricant conduit assembly is located external to the housing15. An electric vehicle comprising: the electric drive unit according to any one of claim 11 to claim 14; and a power source configured to supply electrical power to the electric machine of the electric drive unit.

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