Lubricant sump

Abstract

A fluid sump for an electric drive unit (EDU) assembly, the fluid sump comprising a sump housing defining an interior sump volume configured to receive a supply of fluid and a breather conduit configured to facilitate a flow of air out of the interior sump volume, the breather conduit extending between a first open end located in the interior sump volume, and a second open end; wherein the first open end and the second open end each define a central axis, and wherein the central axis of the first open end is laterally offset, with respect to the fluid sump, from the central axis of the second open end.

Description

[0001] LUBRICANT SUMP

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a fluid sump. Aspects of the invention relate to an electric drive unit (EDU) assembly and to a vehicle.

[0004] BACKGROUND

[0005] It is known to provide electrical drive unit (EDU) assemblies in vehicles, for example in Battery Electric Vehicles (BEVs). The EDU assembly provides the drive to propel the vehicle forward. EDU assemblies typically include a fluid sump, for example a lubricant sump, for receiving a working fluid which may be circulated around the EDU assembly. The fluid sump may include a breather conduit for facilitating airflow into and out of the fluid sump.

[0006] In use, when the EDU assembly is in articulation, the breather conduit is more likely to become blocked at particular locations, for example at a perimeter of the fluid sump. The blockages may in turn cause an airlock and prevent the fluid sump supplying fluid to the EDU assembly. In order to help prevent blockages of the breather conduit assembly, it would be optimal to locate the breather conduit at a centre of the sump housing and at the top of the sump housing. However, due to packaging constraints, it may not be possible to locate the breather conduit in the optimal location and the breather conduit may instead be located at a location where it is more likely to get blocked.

[0007] It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

[0008] SUMMARY OF THE INVENTION

[0009] Aspects and embodiments of the invention provide a fluid sump, an electric drive unit (EDU) assembly and a vehicle, as claimed in the appended claims.

[0010] According to an aspect of the present teachings, there is provided a fluid sump comprising: a sump housing defining an interior sump volume configured to receive a supply of fluid; and a breather conduit configured to facilitate a flow of air out of the interior sump volume, the breather conduit extending between a first open end located in the interior sump volume, and a second open end; wherein the first open end and the second open end each define a central axis, and wherein the central axis of the first open end is laterally offset, with respect to the sump, from the central axis of the second open end.

[0011] Optionally, the fluid sump is for an electric drive unit (EDU) assembly.

[0012] In use, when the EDU assembly is in operation, the breather conduit is more likely to become blocked on occasions and at particular locations, for example at a perimeter of the sump housing, owing to acceleration or inclination of the vehicle in which the EDU is fitted. The blockages may in turn cause an airlock and prevent the fluid sump supplying fluid to the EDU assembly. In order to help prevent blockages of the breather conduit assembly, it would be optimal to locate the breather conduit at a centre of the sump housing and at the top of the sump housing. However, due to packaging constraints, it may not be possible to locate the breather conduit in the optimal location and the first open end may instead be located at a location where it is more likely to get blocked.

[0013] Providing the first open end laterally offset from the second open end helps to enable the first open end to facilitate a flow of air out of the interior sump volume when the EDU assembly is inclined and the first open end would otherwise be blocked if adjacent an edge of the sump that is a lowest part of the sump, gravitationally, given the inclination (or acceleration) of the vehicle in which the EDU is disposed. This helps to reduce the likelihood of the breather conduit becoming blocked and enables a supply of fluid to reach the EDU assembly.

[0014] Optionally, the fluid is a working fluid configured to circulate around the EDU assembly. Optionally, the fluid is a liquid. Optionally, the fluid is a coolant or a lubricant.

[0015] Optionally, a distance between the second open end and a perimeter edge of the sump housing is less than a distance between the first open end and the perimeter edge of the sump housing.

[0016] The distance between the second open end and the perimeter edge being less than the distance between the first open end and the perimeter edge helps to move the first open end closer to a position where the first open end is less likely to become blocked, thereby reducing the likelihood of the breather conduit becoming blocked, particularly when the EDU assembly is inclined. Additionally, providing the second open end at the perimeter improves packing of the EDU assembly.

[0017] Optionally, the lateral direction with respect to the fluid sump is defined as a direction extending between opposing sides of the perimeter edge.

[0018] Optionally, the first open end is located in a central region of the sump housing.

[0019] Advantageously, providing the first open end in the central region moves the first open end towards a position where the first open end is less likely to become blocked, whilst enabling the second open end to remain laterally offset from the first open end for packaging reasons.

[0020] Optionally, the sump housing comprises a base wall and a sidewall extending therefrom. Optionally, the second open end is located closer to the sidewall than to the first open end.

[0021] Advantageously, providing the second open end closer to the sidewall than to the first open end enables the first open end to be located at a position where the first open end is less likely to become blocked, whilst the second open end remains at a remote location for packaging.

[0022] Optionally, the breather conduit follows a non-linear path. Optionally, the breather conduit follows a non-linear path extending in a substantially horizontal plane and / or in a substantially vertical plane.

[0023] Advantageously, the breather conduit following a non-linear path helps to improve packaging of the breather conduit assembly within the fluid sump.

[0024] Optionally, the non-liner path may be circuitous, define one or more deviations and / or comprise one or more angled sections.

[0025] Optionally, the circuitous path deviates from the most direct route between the first open end and the second open end.

[0026] Optionally, the breather conduit comprises one or more curved portions defining the non-linear path.

[0027] Optionally, the one or more curved portions curve through the horizontal plane and / or through the vertical plane.

[0028] Advantageously, providing the one or more curved portions help to improve packaging of the breather conduit within the fluid sump. Additionally, the one or more curved portions may help to improve airflow through the breather, and may be easier to manufacture.

[0029] Optionally, the breather conduit extends across the interior sump volume of the sump housing between the first open end and the second open end and / or wherein the breather conduit extends externally from the fluid sump.

[0030] Advantageously, providing the breather conduit extending across the interior sump volume and / or extending externally helps to improve packaging of the breather conduit within the fluid sump.

[0031] Optionally, the sump housing comprises a top wall providing a cover to the interior sump volume. Optionally, the top wall at least partially defines the breather conduit.

[0032] Advantageously, the top wall at least partially defining the breather conduit helps to improve ease of the assembly of the breather conduit to the fluid sump as well as being space efficient.

[0033] Optionally, the fluid sump comprises a breather conduit section secured to the top wall to define the breather conduit.

[0034] Optionally, the breather conduit section is welded to or clipped to the top surface to define the breather conduit.

[0035] Advantageously, providing the breather conduit section to define the breather conduit helps to improve ease of assembly of the fluid sump and breather conduit assembly, particularly when the components are manufactured using a moulding process.

[0036] Optionally, the central axis of the first open end is orientated obliquely with respect to the second open end. Advantageously, providing the first open end orientated obliquely to the second open end helps to reduce the likelihood of fluid (for example coolant or lubricant) being directed into the first open end, in use.

[0037] Optionally, the central axis of the first open end may be orientated perpendicularly to the central axis of the second open end.

[0038] Optionally, the central axis of the first open end may be orientated parallel to the central axis of the second open end.

[0039] Optionally, the breather conduit assembly comprises two or more first open ends located in the interior sump volume and connected to the second open end by the breather conduit.

[0040] Advantageously, providing more than one first open end helps to reduce the likelihood of blockages of the breather conduit because even if one of the first open ends is blocked at a particular inclination angle, the other first open end may still receive the flow of air therethrough. Additionally, providing more than one first open end may help to improve packaging, because the first open ends can be located at a greater variety of locations.

[0041] Optionally, the fluid sump comprises a sump outlet and a fluid pick-up pipe connected to the sump outlet, wherein the fluid pick-up pipe is configured to provide a fluid from the fluid sump to one or more drive unit components.

[0042] Advantageously, the pick-up pipe and sump outlet facilitate the recirculation of fluid around the EDU assembly. Optionally, the fluid sump is formed of a moulded plastic.

[0043] Advantageously, moulding allows for the creation of intricate and complex shapes, and has a high production efficiency.

[0044] According to another aspect of the present teachings, there is provided an electric drive unit (EDU) assembly, comprising: an EDU housing defining an interior EDU volume for one or more drive unit components; a fluid sump according to a previous aspect, located below the interior EDU volume; and wherein the breather conduit provides a flow path between the interior sump volume and the interior EDU volume.

[0045] In use, when the EDU assembly is inclined, the breather conduit is more likely to become blocked at particular locations, for example at a perimeter of the sump housing. The blockages may in turn cause an airlock and prevent the fluid sump supplying fluid to the EDU assembly. In orderto help prevent blockages of the breather conduit assembly, it would be optimal to locate the breather conduit at a centre of the sump housing and at the top of the sump housing. However, due to packaging constraints, it may not be possible to locate the breather conduit in the optimal location and the first open end may instead be located at a location where it is more likely to get blocked. Providing the first open end laterally offset from the second open end helps to enable the first open end to facilitate a flow of air out of the interior sump volume when the EDU assembly is inclined and the first open end would otherwise be blocked. This helps to reduce the likelihood of the breather conduit becoming blocked and enables a supply of fluid to reach the EDU assembly.

[0046] According to another aspect of the present teachings, there is provided a vehicle comprising an EDU assembly according to a previous aspect.

[0047] Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0050] Figure 1 shows a vehicle;

[0051] Figure 2 schematically shows functional units and a control system of the vehicle of Figure 1 ;

[0052] Figure 3 shows a perspective view of an underside of an EDU assembly of the vehicle of Figure 1 ;

[0053] Figure 4 shows a front view of the EDU assembly of Figure 3;

[0054] Figures 5A and 5B show cross-sectional side views of the EDU assembly of Figure 3;

[0055] Figure 6 shows a perspective view of a fluid sump of the EDU assembly of Figure 3;

[0056] Figure 7 shows an alternative perspective view of the fluid sump of Figure 6;

[0057] Figure 8 shows a cross-sectional view of the fluid sump of Figure 6 with a breather conduit according to the present teachings; and

[0058] Figure 9 shows a cross-sectional view of the fluid sump of Figure 6 with an alternative embodiment of a breather conduit according to the present teachings.

[0059] DETAILED DESCRIPTION

[0060] Figures 1 and 2 show an example of an electric vehicle (EV) 10. The EV 10 has a battery or battery pack 40. The battery 40 is mounted to and supported by the vehicle body structure, in use. The battery 40 may be recharged from an external electrical source. The EV 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 EV 10 has at least one electric drive unit (EDU) assembly 20, 30 by which one or more of the wheels 12, 14 are driven. In the illustrated embodiment, the EV 10 comprises two electric drive unit assemblies 20, 30, each associated with one of the pairs of wheels 12, 14. In other embodiments, the EV 10 may have a dedicated EDU assembly for each of the front wheels 12 and / or a dedicated EDU assembly for each of the rear wheels 14. In the illustrated embodiment, the front wheels 12 are driven by a first EDU assembly 20. The first EDU assembly 20 includes a first electric machine 22, a front transmission 24 and power electronics 26. The rear wheels 14 are driven by a second EDU assembly 30. The second EDU assembly 30 includes a second electric machine 32, a rear transmission 34 and power electronics 36. The first EDU assembly 20 and the second EDU assembly 30 each receive a DC supply from battery 40. The first EDU assembly 20 can be considered a first propulsion unit, and the second EDU assembly 30 can be considered 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.

[0061] In other embodiments, the EV 10 may include only one EDU assembly 20, 30. For example, the second EDU assembly 30 may be omitted in embodiments where the EV 10 is a “front-wheel drive” vehicle, or the first EDU assembly 20 may be omitted in embodiments where the EV 10 is a “rear-wheel drive” vehicle. In further embodiments, one or more of the wheels 12, 14 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.

[0062] Referring now to Figure 3, a perspective view of an underside of the first EDU assembly 20 is illustrated. The first EDU assembly 20 will be referred to hereafter as the EDU assembly 20. It shall be appreciated that although the teachings are described in relation to the first EDU assembly 20, the invention is also applicable to the second EDU assembly 30, or to any alternative arrangements of first and / or second EDU assembly 20, 30, for example those described above.

[0063] The EDU assembly 20 includes an EDU housing 50 defining an interior EDU volume 51 (visible in Figures 5A and 5B) for one or more drive unit components. The EDU assembly 20 also includes a lubrication recirculation system, which supplies lubricant to one or more rotating components of the EDU assembly 20 (e.g. electric machine 22, bearings and / or a differential). The lubricant, such as oil, may both lubricate and cool those rotating components. The lubricant recirculation system includes a lubricant sump 52 into which the lubricant drains after having been supplied to the parts it lubricates. The lubricant sump 52 is located below the interior EDU volume 51 of the EDU housing 50, as illustrated in Figures 4, 5A and 5B. The lubricant recirculation system may also include a lubricant pump (not shown) which supplies lubricant along a flow path between the lubricant sump 52 and the interior EDU volume 51 of the EDU housing 50. The flow path is at least in part defined by one or more conduits 54, 61. The lubricant which is supplied into the EDU housing 50 is then drained into the sump 52, for example at a lower end of the EDU housing 50.

[0064] The sump 52 is formed of a moulded plastic, for example polyethylene (PE) or polypropylene (PP). Moulding allows for the creation of intricate and complex shapes, and has a high production efficiency. Using a plastics material helps to reduce an overall weight of the EDU assembly 20 when the sump 52 is assembled thereto. It shall be appreciated that in alternative embodiments, the sump 52 may be formed from any suitable material using any suitable manufacturing process. A lubricant pick-up pipe 54 is provided adjacent to or in the sump 52. The lubricant pick-up pipe 54 has a lubricant inlet aperture through which lubricant may be drawn into the pick-up pipe 54 by means of the lubricant pump. The lubricant pick-up pipe 54 also includes a lubricant outlet aperture 56 through which lubricant may be drawn from the pick-up pipe 54 to the interior EDU volume 51 . It shall be appreciated that the outlet aperture 56 may be connected to additional lubricant conduits for directing lubricant to specific locations of the interior EDU volume 51. Furthermore, it is submitted that in some embodiments, more than one pick-up pipe 54 or conduit may be provided.

[0065] The sump 52 includes a sump housing 53, illustrated in Figures 6 and 7. The sump housing 53 defines an interior sump volume 58 configured to receive a supply of lubricant. One or more sump inlets 60 are provided in the sump housing 53 to allow lubricant contained within the interior EDU volume 51 to be transferred (e.g. drained) into the interior sump volume 58. In Figures 6 and 7, two sump inlets 60 are provided, however it shall be appreciated that in alternative embodiments, any suitable number of sump inlets 60 may be provided. The sump inlets 60 may be connected to drainage conduits 61 . The drainage conduits 61 may extend from the sump inlets 60 and include outlets (not shown) which drain lubricant into the interior sump volume 58. The sump inlets 60 are located higher than the outlets with respect to a ground surface such that lubricant may flow under gravity from the sump inlets 60, through the drainage conduits 61 and into the interior sump volume 58.

[0066] It shall be appreciated that in alternative embodiments, any suitable drainage arrangement may be used to transfer lubricant from the interior EDU volume 51 to the interior sump volume 58. In some embodiments, the drainage conduits 61 may be omitted and the lubricant may be drained directly through the sump inlets and to the interior sump volume 58.

[0067] The sump 52 may include a substantially planar base wall 52a. The term “base” is taken to mean the wall of the sump housing 53 which is closest to the ground surface when the EDU assembly 20 is mounted to the vehicle (i.e. in use). In particular, an interior base surface of the base wall 52a may be substantially planar. In this context, the term “substantially planar” will be understood to mean that a majority of the base surface is planar, however the base may include non-planar features and the base may not be exactly planar due to draft angles of casting cores used to produce the sump 52. The sump 52 includes a sidewall 52b extending from the base wall 52a. In the embodiment illustrated in Figures 6 to 9, the sidewall 52b is a continuous side wall. In alternative embodiments, any suitable number of sidewalls 52b may be provided, for example distinct sidewalls 52b. The sump 52 also includes a top wall 52c providing a cover to the interior sump volume 58. The term “top” is taken to mean the wall of the sump housing 53 furthest away from a ground surface when the EDU assembly 20 is mounted to the vehicle 10 (i.e. in use). The top wall 52c extends from the sidewall 52b and opposes the base wall 52b. In the embodiment shown in the Figures, the top wall 52c forms a cover so as to enclose the interior sump volume 58. The interior sump volume 58 is therefore defined by and enclosed by the base wall 52a, the sidewall 52b and the top wall 52c.

[0068] The top wall 52c includes an increase in height from a first side of the sump housing 53 to a second side of the sump housing 53. This helps to enable the sump inlets 60 to be located higher than the outlets such that lubricant may flow under gravity from the sump inlets 60, through the drainage conduits 61 and into the interior sump volume 58. The drainage conduits 61 may form part of the top wall 52c, as will be described in more detail below.

[0069] As illustrated in Figures 6 to 9, the sump housing 53 is substantially U-shaped in plan view. As such, the base wall 52a and the top wall 52c are substantially U-shaped in plan view. The U-shape is defined by a first housing arm 53a and a second housing arm 53b spaced apart from the first housing arm 53a. In the embodiment of the Figures, the sump housing 53 defines an irregular U-shape. The first housing arm 53a of the sump housing 53 is wider and longer than the second housing arm 53b of the sump housing 53. It shall be appreciated that in alternative embodiments, the sump housing 53 may be a regular U-shape (i.e. the first housing arm 53a may be the same width and length as the second housing arm 53b). Alternatively, the sump housing 53 may be any suitable shape, for example L-shaped, C-shaped, rectangular, circular etc. The shape of the sump housing 53 may depend on the EDU assembly 20 to which the sump housing 53 is mounted.

[0070] The sump 52 includes a breather conduit 62 configured to facilitate a flow of air in and out of the interior sump volume 58. It shall be appreciated that the breather conduit 62 may be further configured to facilitate a flow of air into the interior sump volume 58. The breather conduit 62 provides a flow path between the interior sump volume 58 and the interior EDU volume 51 . As such, air may be vented from the interior sump volume 58 to the interior EDU volume 51 . The breather conduit 62 helps to regulate pressure within the interior sump volume 58 so as to help prevent a vacuum from forming within the sump 52. Furthermore, the breather conduit 62 helps to improve ventilation within the sump 52 by allowing the exchange of air into and out of the interior sump volume 58.

[0071] It shall be appreciated that the breather conduit 62 may define the flow path between the interior sump volume 58 and any suitable location of the interior EDU volume. By way of example, the breather conduit 62 may define the flow path between the interior sump volume 58 and a link shaft cavity (as described further below) of the EDU housing 50. Alternatively, the breather conduit 62 may define a flow path between the interior sump volume 58 and an alternative cavity of the EDU housing 50. In some embodiments, the breather conduit 62 may define a flow path between the interior sump volume 58 and a location external of the EDU assembly 20, possibly via the link shaft cavity.

[0072] The breather conduit 62 extends between a first open end 64 located in the interior sump volume 58 and a second open end 66. The second open end 66 is located in the interior EDU volume 51 , for example in the link shaft cavity of the interior EDU volume 51 . The first open end 64 and the second open end 66 each define a central axis a-a, b-b. The central axis a-a of the first open end 64 is laterally offset, with respect to the sump housing 53, from the central axis b-b of the second open end 66. The lateral direction with respect to the fluid sump 52 is defined as any direction extending between opposing sides of a perimeter edge 55 of the fluid sump 52. Put another way, the lateral direction with respect to the fluid sump 52 may include any direction extending substantially parallel to the base wall 52a. It shall therefore be appreciated that the first open end 64 may be laterally offset from the second open end 66 in more than one lateral direction. Laterally offset is taken to describe an arrangement of the first open end 64 and the second open end 66 where the first open end 64 and second open end 66 are not co-axial with respect to the vertical direction, or not vertically aligned.

[0073] In use, when the EDU assembly 20 is in operation, the breather conduit 62 is more likely to get blocked at particular locations, for example at or towards the perimeter edge 55 of the sump housing 53. Blockages at the edges are more likely due to accelerations of the vehicle during increase and decrease in speeds or during cornering, whereas liquid only traverses central regions rather than collect there for any extended period. Blockages at the edges can also due to the vehicle in which the EDU is fitted being driven, parked or otherwise operated on an incline. Blockages may cause an airlock and prevent the fluid sump 52 supplying fluid to the EDU assembly 20. In order to help prevent blockages of the breather conduit 62, it would be optimal to locate the breather conduit 62 at a centre of the sump housing 53 and at or towards the top wall 52c of the sump housing 53. In such an example, the breather conduit 62 may be a chimney, such that the first open end 64 and the second open end 66 are axially aligned in a direction extending transversely to the base wall 52a. However, due to packaging constraints, it may not be possible to locate the breather conduit 62 in the optimal location, and the first open end 64 may instead be located at a location where is it more likely to get blocked, for example at or towards the perimeter edge 55.

[0074] Providing the first open end 64 laterally offset from the second open end 66 towards the central region of the sump helps to enable the first open end 64 to facilitate the flow of air out of the interior sump volume 58 when the EDU assembly 20 is in operation and the first open end 64 might otherwise be blocked. This helps to reduce the likelihood of the breather conduit 62 becoming blocked, and enables a supply of lubricant to reach rotating components of the EDU assembly 20. In the embodiment illustrated in Figures 5A and 5B, the central axis a-a of the first open end 64 is orientated substantially parallel with respect to the central axis b-b of the second open end 66.

[0075] In alternative embodiments, the central axis a-a of the first open end 64 may be orientated obliquely to the central axis b-b of the second open end 66. Providing the first open end 64 orientated obliquely to the second open end 66 helps to reduce the likelihood of fluid, for example coolant or lubricant, being direction into the first open end 64, in use. It shall be appreciated that the term “laterally offset” is taken to mean that there is a lateral spacing between the first open end 64 and the second open end 66. In embodiments where the central axes a-a, b-b of the first open end 64 and the second open end 66 are arranged obliquely, the fact that the central axes a-a, b-b may intersect and diverge from the point of intersection falls under the intended definition of the term “laterally offset”.

[0076] The second open end 66 is located in the interior EDU volume 51 , as illustrated in Figures 5A and 5B. As such, the flow path is defined between the interior sump volume 58 and the interior EDU volume by the first open end 64 and the second open end 66. It shall be appreciated that due to components of the EDU assembly 20 being located above the sump 52 in the interior EDU volume, there are locations at which the second open end 66 would be blocked or obstructed. In the embodiment of the Figures, the second open end 66 is located in a cavity of the EDU housing 50, for example in the link shaft cavity. The link shaft cavity a relatively large volume in the EDU and provides both a ready supply of air, or a ready receptacle for air, depending on the conditions in the sump volume. In the embodiments shown in Figures 5A and 5B, the breather conduit includes a chimney portion 66a extending out of the sump 52, and the chimney portion 66a terminates at the second open end 66. The chimney portion 66a is substantially linear. Put another way, the chimney portion 66a extends substantially axially or vertically.

[0077] It shall be appreciated that the locations at which the second open end 66 may be located to facilitate the flow of air therethrough are dependent on the type of EDU assembly 20 and the location of components within the EDU assembly 20. It shall be appreciated that the first open end 64 may act as an outlet or an inlet, and the second open end 66 may act as an outlet or an inlet. The first open end 64 acts as an inlet and the second open end 66 acts as an outlet when air flows from the interior sump volume 58 to the interior EDU volume 51 . The first open end 64 acts as an outlet and the second open end 66 acts as an inlet when air flows from the interior EDU volume 51 to the interior sump volume 58.

[0078] A lateral distance between the second open end 66 and the perimeter edge 55 of the sump housing 53 is less than a lateral distance between the first open end 64 and the perimeter edge 55 of the sump housing 53. In particular, a minimum distanced between the second open end 66 and the perimeter edge 55 is less than a minimum distance between the first open end 64 and the perimeter edge 55. The second open end 66 is located closer to the perimeter edge 55 of the sump housing 53 than the first open end 64 is. Put another way, a distance between the second open end 66 and the perimeter edge of the sump housing 53 is less than a distance between the first open end 64 and the perimeter edge of the sump housing 53. Providing the second open end 66 closer to the perimeter edge 55 than the first open end 64 helps to move the first open end 64 closerto a position where the first open end 64 is less likely to become blocked, thereby reducing the likelihood of the breather conduit 62 becoming blocked. Additionally, providing the second open end 66 at ortowards the perimeter edge 55 improves packaging of the EDU assembly 20. In the embodiment shown in the Figures, the second open end 66 is located at a corner of the sump 52.

[0079] As illustrated in Figure 8, the first open end 64 is located in a central region (identified approximately by the dotted line C) of the sump housing 53. Providing the first open end 64 in the central region moves the first open end 64 towards a position where the first open end 64 is less likely to become blocked when the EDU assembly 20 is operating on an incline, for instance, whilst enabling the second open end 66 to remain laterally offset from the first open end 64 for packaging reasons. It shall be appreciated that the term “central region” may be defined as any location which is closer to the optimal location of the sump housing 53 for locating the first open end 64 than to the perimeter edge 55 (or sidewall 52b). In a substantially rectangular sump 52, the optimal location of the sump housing 53 for locating the first open end 64 would be at a centre point of the sump housing 52 located approximately equidistantly between the side walls. In the U-shaped sump 52 shown in Figures 8 and 9, the optimal location is a region located equidistantly between opposing sides of the sidewall 52b. As such, the central region C may be dependent on the shape of the sump 52. The central region C shown in Figures 8 and 9 is substantially L-shaped.

[0080] The second open end 66 is located closer to the sidewall 52b than to the first open end 64. Put another way, a minimum distance between the sidewall 52b and the second open end 66 is less than a lateral distance between the second open end 66 and the first open end 64. Providing the second open end 66 closer to the sidewall than to the first open end 64 enables the first open end 64 to be located at a position where the first open end 64 is less likely to become blocked, whilst the second open end 66 remains at a remote location for packaging.

[0081] As illustrated in Figures 5A, 5B, 8 and 9, the breather conduit 62 follows a non-linear path. In particular, the breather conduit 62 follows a non-linear path extending in a substantially vertical plane and / or in a substantially horizontal plane. The breather conduit 62 illustrated in the Figures follows a non-linear path extending in the substantially vertical and horizontal planes. In alternative embodiments, the breather conduit 62 may follow a linear path extending in one of the horizontal or vertical planes. The non-linear breather conduit 62 helps to improve packaging of the breather conduit 62 within the fluid sump 52 by avoiding components of the sump, for example drainage and / or pick-up conduits 60, 54. The non-linear path may be circuitous, defining one or more deviations and / or comprising one or more angled sections. The term “circuitous” is taken to mean that the path deviates from the most direct route between the first open end 64 and the second open end 66.

[0082] In the embodiment illustrated in Figures 5A and 8, the breather conduit 62 includes one or more curved portions defining the non-linear path. The one or more curved portions curve through both the horizontal plane, as illustrated in Figure 8, and the vertical plane, as illustrated in Figure 5A. In particular, the breather conduit 62 includes one or more curved portion extending through the vertical plane, and the breather conduit 62 includes two curved portions extending through the horizontal plane. As such, the breather conduit 62 as shown in Figure 5A is substantially L-shaped in side view and the breather conduit as shown in Figure 8 is substantially S-shaped in plan view. It shall be appreciated that as illustrated in Figure 5A, the breather conduit 62 may rotate through 90° towards the first open end 64 such that the first open end 64 is orientated parallel to the second open end 66. It shall be appreciated that the breather conduit 62 shown in the Figures is exemplary, and that any suitable shape of breather conduit 62 may be provided. For example, any suitable number of curved portions may be provided in the horizontal plane and / or in the vertical plane. Substantially straight angled portions may be provided instead of or as well as the curved portions. The path followed by the breather conduit 62 may be dependent on the shape of the sump housing 53 and / or components of the sump housing 53 which may obstruct a direct path of the breather conduit 62. However, it is desirable to avoid any low-spots where lubricant entering the breather conduit might collect. That is, any lubricant that does enter the breather conduit needs to be able to drain back into the sump 52, at least when the vehicle is on horizontal ground.

[0083] Providing one or more non-linear portions, for example curved portions, helps to improve packaging of the breather conduit within the fluid sump 52. Additionally, providing a breather conduit 62 with may follow a variety of non-linear paths improves versatility of the breather conduit 62, and means that the breather conduits 62 may be used in existing sumps 52 with minimal modifications to the sump 52 to make space for the breather conduit 62 (i.e. the path of the breather conduit 62 may be designed to fit the sump 52 as opposed to the other way round).

[0084] In the embodiment illustrated in Figure 5A, the breather conduit 62 extends across the interior sump volume 58 of the sump housing 53 between the first open end 64 and the second open end 66. Figure 5B shows an alternative embodiment in which the breather conduit 62 extends externally to the fluid sump 52. It shall be appreciated that in some embodiment, the breather conduit 62 may extend both across the interior sump volume 58 and externally to the fluid sump 52. In the embodiment of Figure 5B, the chimney portion 66a extends out of the fluid sump 52 and the breather conduit 62 may extend from the chimney portion 66a, i.e. tap off from the chimney portion 66a and into the interior sump volume 58. In this case, the chimney portion opens into the sump near an edge, but the tap off from the chimney portion to the central region C mitigates against the risk of the opening at the edge being blocked.

[0085] Figures 6 and 7 shows views of the fluid sump 52 removed from the EDU assembly 20. In the embodiment shown in Figure 6 and 7, the top wall 52c at least partially defines the drainage conduit 61 . The top wall 52c includes a recess, groove or channel 68, illustrated in Figure 7, which defines a portion of the drainage conduit

[0086] 61 . As illustrated in Figure 6, the sump 52 includes a drainage conduit section 70 secured to the top wall 52c. In particular, the drainage conduit section 70 is secured to the recess, groove or channel 68 so as to form the drainage conduit 61. The recess, groove or channel 68 is substantially semi-circular in cross-section and the drainage conduit section 70 is substantially semi-circular in cross-section such that when the drainage conduit section 70 is secured to the recess, groove or channel 68 a drainage conduit 62 with a substantially circular cross-section is formed. The drainage conduit section 70 may be welded, for example friction or laser welded, or clipped to the top wall 52c to define the drainage conduit 61 . Providing the drainage conduit section 70 to define the drainage conduit 61 helps to improve ease of assembly of the fluid sump 52 and drainage conduit

[0087] 62, particularly when the components are manufactured using a moulding process. This is because hollow sections, such as conduits, are complex to manufacture using moulding processes and may involve additional steps such as using sliders to form the conduit.

[0088] It shall be appreciated that although not shown, the teachings described above in relation to the drainage conduit section 70 and recess, groove or channel 68 may be applicable to the breather conduit 62. As such, the top wall 52c may at least partially define the breather conduit 62. In particular, the top wall 52c may include a recess, groove or channel, and a breather conduit section may be secured to the recess, groove or channel in substantially the same way as described above to provide the breather conduit 62. It shall be appreciated that in some embodiments, the drainage conduit 61 and / or the breather conduit 62 may be integrally formed with the top wall 52c, for example using a moulding process.

[0089] Figure 9 shows an alternative embodiment of the breather conduit 62. In the embodiment of Figure 9, the breather conduit 62 includes two or more first open ends 64a, 64b located in the interior sump volume 58 and connected to the second open end 66 by the breather conduit 62. As such, the breather conduit 62 may include more than one branch for connecting each first open end 64a, 64b to the second open end 66. Providing more than one first open end 64a, 64b helps to reduce the likelihood of blockages of the breather conduit 62 because even if one of the first open ends 64a, 64b is blocked at a particular inclination angle or under a particular acceleration, the other first open end 64a, 64b may still receive a flow of air therethrough. Additionally, providing more than one first open end 64 may help to improve packaging because the first open ends 64 can be located at a greater variety of locations (i.e. at less optimal locations). It shall be appreciated that in embodiments with more than one first open end 64, the breather conduit 62 may be a breather conduit assembly including a number of conduit sections secured together. The breather conduit 62 may include one or more valves in some embodiments for regulating flow therethrough.

[0090] In the embodiment shown in Figure 9, two first open ends 64a, 64b are provided. The first open ends 64a, 64b are located in the central region C of the sump housing 53. It shall be appreciated that in alternative embodiments, more than two first open ends 64a, 64b may be provided at any suitable location within the sump housing 53. By way of example, the open ends 64a, 64b may be located closer to the perimeter edge 55 than to the central region C (i.e. outside of the central region C). It shall be appreciated that providing first open ends 64a, 64b closer to the perimeter edge 55 than to the central region C may be useful for packaging, and may be made possible by the provision of more than one first open end 64a, 64b. Where there are first open ends 64a, 64b located towards the perimeter edge 55, it is advantageous that the two or more first open ends 64a, 64b are located spaced apart, for example on opposing sides of the perimeter edge 55 such that when one of the first open ends 64a, 64b is blocked, the other first open end or ends 64a, 64b is less likely to be blocked. It shall be appreciated that the teachings described in relation to Figures 1 to 8 are applicable to the embodiment of Figure 9.

[0091] In an alternative embodiment, the sump 52 may be a fluid sump for receiving a supply of an alternative fluid to lubricant, for example an alternative working fluid. The working fluid may be any fluid configured to circulate around the EDU assembly 20, for example a working liquid. By way of example, the working fluid may be coolant and the fluid sump may be a coolant sump for receiving a supply of coolant.

[0092] 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 fluid sump for an electric drive unit assembly, the fluid sump comprising: a sump housing defining an interior sump volume configured to receive a supply of fluid; and a breather conduit configured to facilitate a flow of air out of the interior sump volume, the breather conduit extending between a first open end located in the interior sump volume, and a second open end located outside the interior sump volume; wherein the first open end and the second open end each define a central axis, and wherein the central axis of the first open end is laterally offset, with respect to the fluid sump, from the central axis of the second open end, and the distance between the central axis of the second open end and a perimeter edge of the sump housing is less than a distance between the central axis of the first open end and the perimeter edge of the sump housing.

2. The fluid sump according to claim 1 , wherein the first open end is located in a central region of the sump housing.

3. The fluid sump according to claim 1 or 2, wherein the sump housing comprises a substantially planar base wall configured to be substantially horizontal in use, and a sidewall extending therefrom, the side wall defining said perimeter edge.

4. The fluid sump according to any preceding claim, wherein the breather conduit follows a nonlinear path.

5. The fluid sump according to claim 4, wherein the breather conduit comprises one or more curved portions defining the non-linear path.

6. The fluid sump according to any preceding claim, wherein the breather conduit extends across the interior sump volume of the sump housing between the first open end and the second open end and / or wherein the breather conduit extends externally from the fluid sump.

7. The fluid sump according to any preceding claim, wherein the sump housing comprises a top wall providing a cover to the interior sump volume, and wherein the top wall at least partially defines the breather conduit.

8. The fluid sump according to claim 7, wherein the fluid sump comprises a breather conduit section secured to the top wall to define the breather conduit.

9. The fluid sump according to any preceding claim, wherein the central axis of the first open end is orientated obliquely with respect to the second open end.

10. The fluid sump according to any preceding claim, wherein the breather conduit comprises two or more first open ends located in the interior sump volume and connected to the second open end by the breather conduit.11 . The fluid sump according to any preceding claim, comprising a sump outlet and a fluid pickup pipe connected to the sump outlet, wherein the fluid pick-up pipe is configured to provide a fluid from the fluid sump to one or more drive unit components.

12. The fluid sump according to any preceding claim, wherein the fluid sump is formed of a moulded plastic.

13. An electric drive unit assembly, comprising: an EDU housing defining an interior EDU volume for one or more drive unit components; a fluid sump according to any preceding claim, located below the interior EDU volume; and wherein the breather conduit provides a flow path between the interior sump volume and the interior EDU volume.

14. A vehicle comprising an EDU assembly according to claim 14.

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