An electric drive unit assembly and a removable plug for an electric drive unit assembly

Abstract

An electric drive unit assembly has an associated removable plug 60. The electric drive unit assembly includes a housing 10 with a first aperture 64, an interior wall 36 within the housing, the interi

Description

TECHNICAL FIELD The present disclosure relates to an electric drive unit assembly and to a removable plug for an electric drive unit assembly. An aspect of the invention also relates to a vehicle comprising an electric drive unit assembly in accordance with the present invention. BACKGROUND It is known to provide one or more electric drive units in a vehicle, e.g. in a road vehicle or an off-road vehicle. Known electric drive units typically include a numberof gears which are lubricated by a supply of high-pressure oil. Such electric drive units also typically have an internal baffle to separate the region in which the gears are mounted from a sump region, to prevent churning of the oil by the gears within the sump region, which would result in energy losses. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide an electric drive unit assembly, a removable plug for an electric drive unit assembly and a vehicle comprising an electric drive unit assembly in accordance with the present invention, as claimed in the appended claims. The present invention provides an electric drive unit assembly comprising a removable plug having first and second closure portions for releasably closing first and second apertures in a housing and an interior wall respectively of the assembly. According to an aspect of the present invention there is provided an electric drive unit assembly comprising: a housing; an interior wall within the housing; a first aperture in the housing; a second aperture in the interior wall, aligned with the first aperture in the housing; and a removable plug having first and second closure portions for releasably closing the first and second apertures in the housing and the interior wall respectively. In some electric drive unit assemblies, moving gears are separated from a main sump region by a baffle formed by an interior wall, in order to reduce energy losses which would otherwise arise from churning of fluid (e.g. oil) if the moving gears were located in the main sump region. However, such an arrangement makes it difficult to drain all of the fluid within the assembly during servicing, as some of the fluid is retained by the baffle. This has a potential detrimental effect on both efficiency and durability and affects the fill volume of fluid to be added to the assembly. The invention helps to maintain the separation of the moving gears from the main sump region in normal use but allows the fluid retained within the baffle during normal use to be drained on removal of the plug. In an embodiment, the housing defines a sump. The interior wall or baffle separates the moving gears of the electric drive unit assembly from the sump, thereby reducing energy losses which would otherwise arise. Optionally, the interior wall forms a baffle configured to define a region for receipt of gears which is separated from the sump. The aperture in the interior wall allows the fluid retained by the interior wall to be drained on removal of the Plug- In an embodiment, each of the first and second closure portions of the removable plug comprises a portion shaped to be received in the respective aperture in the housing and the interior wall. Shaping the first and second closure portions to be received in the first and second apertures respectively assists in the correct positioning of the removable plug. Optionally, the apertures in the housing and in the interior wall are circular. The provision of circular apertures facilitates manufacturing and allows the plug to rotate with respect to the apertures. In an embodiment, at least one of the first closure portion or second closure portion of the removable plug comprises a shoulder which is engageable with the housing or interior wall around a periphery of the respective aperture. The use of a shoulder allows reliable closure of the apertures and facilitates the mounting of a seal, e.g. an O-ring seal, to improve the closure of the apertures. In an embodiment, the removable plug is elongate. Optionally, the first and second closure portions are located at opposite ends of the plug; Locating the first and second closure portions at the opposite ends of an elongate plug allows the plug to be inserted through the aperture in the housing so that the first and second closure portions are positioned adjacent to the first and second apertures in the housing and the interior wall respectively, and by securing the plug in position the apertures in the housing and in the interior wall can be closed. In an embodiment, the removable plug comprises a screw threaded portion which is engageable with a complementarily threaded portion in the housing. This allows the plug to be conveniently be secured in position by engaging the screw-threaded portion with the threaded portion of the housing. In an embodiment, the first aperture in the housing is larger than the second aperture in the interior wall. Insertion of the second closure portion of the removable plug through the first aperture in the housing is facilitated by having the first aperture in the housing larger than the second aperture in the interior wall. In an embodiment, in use the first aperture in the housing is located vertically below the second aperture in the interior wall. Optionally, the second aperture in the interior wall is located at the lowermost point of the interior wall. On removal of the plug, fluid retained within the interior wall is allowed to drain through the second aperture in the wall and then drain out of the first aperture in the housing, allowing all of the fluid within the assembly to be removed. According to another aspect of the invention, there is provided a vehicle comprising an electric drive unit assembly in accordance with the present invention. According to another aspect of the invention, there is provided a removable plug for an electric drive unit assembly comprising a housing and an interior wall, the removable plug comprising: a first closure portion for releasably closing a first aperture in the housing; and a second closure portion for releasably closing a second aperture in the interior wall. This allows a single plug to seal the apertures in the housing and the interior wall, which allows the region defined by the interior wall to be isolated during normal use, but which allows fluid previously retained within the interior wall to drain on removal of the plug. In an embodiment, the first and second closure portions are circular. In an embodiment, at least one of the first closure portion or second closure portion comprises a shoulder portion which is engageable with the housing or interior wall around a periphery of the respective aperture. The use of a shoulder allows reliable closure of the apertures and facilitates the mounting of a seal, e.g. an O-ring seal, to improve the closure of the apertures. In an embodiment, the removable plug comprises an elongate shank and the first and second closure portions are located at opposite ends of the shank. Locating the first and second closure portions at the opposite ends of the plug shank allows the plug to be inserted through the aperture in the housing so that the first and second closure portions are positioned adjacent to the apertures in the housing and the interior wall respectively, and by securing the plug in position the apertures in the housing and in the interior wall can be closed. In an embodiment, the first closure portion is wider than the second closure portion. This requires the first aperture in the housing also to be correspondingly wider, which facilitates insertion of the narrower second closure portion of the removable plug through the first aperture in the housing. In an embodiment, the removable plug comprises an externally screw threaded portion. Optionally, the screw threaded portion is located adjacent to the first closure portion. Optionally, the screw threaded portion is located between the first and second closure portions. This allows the plug to be conveniently be secured in position by engaging the screw-threaded portion with the threaded portion of the housing. 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 anyway and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a front perspective view of a portion of a housing of an electric drive unit assembly in accordance with the present invention; Figure 2 shows a rear perspective view of the portion of the housing of the electric drive unit assembly of Figure 1; Figure 3 shows an exploded front perspective view of the portion of the housing of the electric drive unit assembly of Figure 1; Figure 4 shows a front view of the portion of the housing of the electric drive unit assembly of Figure 1; Figure 5 shows an enlarged view of the portion shown at A in Figure 4; and Figure 6 shows an enlarged vertical cross-section through the portion shown in Figure 6; Figure 7 is a perspective view from above of a drain plug which forms part of the electric drive unit assembly of Figure 1, in accordance with the present invention; and Figure 8 is a perspective view from below of the drain plug of Figure 7. DETAILED DESCRIPTION Figures 1 to 5 illustrate a transmission housing component 10 which forms part of an electric drive unit assembly of a vehicle, for example a road vehicle or an off-road vehicle. In use, the transmission housing component 10 is attached and sealed to adjacent housing components (not shown) to form the housing of the electric drive unit assembly. As shown in Figures 1 to 3, the opposite ends of the housing component 10 are each provided with a continuous, planar, peripheral sealing face 14, 16 which, in use, extend parallel to each other and which seal against a corresponding sealing face of a respective motor housings (not shown), typically separated by a gasket and / or sealing compound to provide a sealing engagement. The opposite ends of the housing component 10 are also provided with a plurality of outwardly projecting apertured lugs 18 having a through hole 20 which in use are aligned with the holes in corresponding apertured lugs in the motor housings and sealed together by means of bolts passing through the aligned holes in the adjacent lugs. The housing component 10 also comprises a generally planar internal dividing wall 24 extending parallel to the planes of the sealing faces 14, 16 which has two circular upper and lower through apertures 26, 28, each having a reinforced periphery 30, 32 for receiving bearings (not shown) for rotatably supporting a shaft (not shown). Figures 1 to 3 also disclose internal baffles 36, 38 in the form of internally-directed, curved planar extensions of the wall 40 between the peripheral sealing faces 14, 16 and each of which has a sealing face 14a, 16a which is coplanar with the respective sealing face 14, 16 and which, in use, sealing abuts a corresponding portion of the respective motor housings. Each of the baffles 36, 38 is located below the lower of the two apertures 28 and is part-circular in shape, arranged coaxially with the centre of the aperture 28 and extending for approximately 120° around the lower edge of the lower aperture 28, and the two baffles 36, 38 are mirror images of each other. Each of the baffles 36, 38 partially separates the housing component 10 into a gear chamber 44, 46 located upwardly and inwardly of the respective baffle 36, 38 and a sump portion 48, 50 located downwardly and outwardly of the respective baffle 36, 38. As best seen in Figures 3 to 6, an elongate plug 60 can be removably secured to the housing component 10. More specifically, a portion of the peripheral wall 62 located on the undersurface of the housing component 10 between its two ends is provided with a circular through drain aperture 64 which is partially threaded at 66. The baffle 36 on the front of the housing component 10 is provided with a smaller, unthreaded circular through aperture 68, aligned with the partially threaded circular drain aperture 64. As shown in the Figures, the elongate plug 60 comprises a cylindrical unthreaded shank portion 70 of slightly smallerdiameterthan the threaded aperture 60, an enlarged head 72 at an outer end, a screw-threaded shank portion 74 between the unthreaded shank portion 70 and the enlarged head 72 and a cylindrical lug portion 76 at the inner end and having the same diameter as the smaller aperture 68. The elongate plug 60 can be inserted through the drain aperture 64 to engage its screw-threaded portion 74 with the internal screw thread 66 of the drain aperture 64 and can be advanced further by rotating the plug 60. This is facilitated by the provision of a hexagonal recess 80 in the end face 82 of the enlarged head 72, in the manner of a conventional sump plug. Further rotation of the plug 60 causes the cylindrical lug portion 76 at the inner end of the plug to be received in the aperture 68 in the baffle 36. As best seen in Figure 6, when the plug 60 has been screwed into its maximum extent, a first annular gasket 84, located between a shoulder formed by the undersurface 86 of the enlarged head 72 and the outer surface of the housing component 10 immediately radially outwardly of the drain aperture 64, seals the plug 60 with respect to the exterior of the housing and prevents discharge of the contents of the sump to the exterior. A second annular gasket 88, mounted on the cylindrical lug portion 76 and seated on an annular shoulder 90 at the junction of the shank portion 70 and the lug portion 76, seals the plug 60 with respect to the gear chamber 44, i.e. the portion ofthe housing component 10 located inwardly of, and above, the baffle 36. It will also be noted that a further elongate through aperture 92 is provided in the planar internal dividing wall 24 above the level ofthe baffles 36, 38 and adjacent to the inner end ofthe aperture 68 in the baffle 36. The internal wall 24 is also provided with three though apertures 94, 96, 98 below and outwardly ofthe baffles 36, 38, so that the sump portions 48, 50 ofthe two gear chambers 44, 46 communicate freely with each other. In use, oil is fed, often under pressure, to the bearings located in the through apertures 26, 28 in the internal dividing wall 24 and to gear components connected to rotating shafts mounted in the bearings and located within the gear chambers 44, 46, and which form part ofthe electric drive unit assembly. However, the baffles 36, 38 ensure that the rotating components within the gear chambers 44, 46 do not come into contact with oil which has collected in the sump portions 48, 50, which would otherwise cause churning ofthe oil within the sump portions and consequent unacceptable losses. However, when it is necessary to drain oil from the housing assembly component 10, the plug 60 is unscrewed and removed from the housing assembly component. This allows oil which has accumulated in the sump regions 48, 50 to drain out ofthe housing via the drain aperture 64. Although the drain aperture 64 is in the sump region 48 below the baffle 36, oil in the sump portion 50 can flow freely into the sump portion 48 via the connecting apertures 94, 96, 98 and can therefore drain out ofthe housing through the drain aperture 64. In addition, removal ofthe plug 60 allows oil which has accumulated in the gear chamber 44 above the baffle 36 to flow out into the sump region 48 through the aperture 68 and from there out ofthe housing via the drain aperture 64. Moreover, oil which has collected in the gear chamber 46 on the opposite side of the internal dividing wall 24 is allowed to flow through the elongate aperture 92 within the dividing wall 24 into the region ofthe gear chamber 44 immediately above the baffle 36 on the opposite side ofthe dividing wall 24, and from there is allowed to flow into the sump region 48 through the aperture 68 and from there out ofthe housing via the drain aperture 64. Consequently, removal of the plug 60 allows the whole of the interior volume of the housing component 10 to be drained of oil without any significant quantity of oil being retained by the internal baffles 36, 38. It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

1. An electric drive unit assembly comprising:a housing;an interior wall within the housing;a first aperture in the housing;a second aperture in the interior wall, aligned with the first aperture in the housing; anda removable plug having first and second closure portions for releasably closing the first and second apertures in the housing and the interior wall respectively.

2. An electric drive unit assembly as claimed in claim 1, wherein the housing defines a sump;and optionally wherein the interior wall forms a baffle configured to define a region for receipt of gears which is separated from the sump.

3. An electric drive unit assembly as claimed in claim 1 or claim 2, wherein each of the first and second closure portions of the removable plug comprises a portion shaped to be received in the respective aperture in the housing and the interior wall;and optionally wherein the apertures in the housing and in the interior wall are circular.

4. An electric drive unit assembly as claimed in any of the preceding claims, wherein at least one of the first closure portion or second closure portion of the removable plug comprises a shoulder which is engageable with the housing or interior wall around a periphery of the respective aperture.

5. An electric drive unit assembly as claimed in any of the preceding claims, wherein the removable plug is elongate;and optionally wherein the first and second closure portions are located at opposite ends of the plug.

6. An electric drive unit assembly as claimed in claim 5, wherein the removable plug comprises a screw threaded portion which is engageable with a complementarily threaded portion in the housing.

7. An electric drive unit assembly as claimed in any of the preceding claims, wherein the first aperture in the housing is larger than the second aperture in the interior wall.

8. An electric drive unit assembly as claimed in any of the preceding claims, wherein in use the first aperture in the housing is located vertically below the second aperture in the interior wall;and optionally wherein the second aperture in the interior wall is located at the lowermost point of the interior wall.

9. A vehicle comprising an electric drive unit assembly as claimed in any of claims 1 to 8.

10. A removable plug for an electric drive unit assembly comprising a housing and an interior wall, the removable plug comprising:a first closure portion for releasably closing a first aperture in the housing; and a second closure portion for releasably closing a second aperture in the interior wall.

11. A removable plug as claimed in claim 10, wherein the first and second closure portions are circular.

12. A removable plug as claimed in claim 10 or claim 11, wherein at least one of the first closure portionor second closure portion comprises a shoulder portion which is engageable with the housing or interior wall around a periphery of the respective aperture.

13. A removable plug as claimed in any of claims 10 to 12, comprising an elongate shank and wherein the first and second closure portions are located at opposite ends of the shank.

14. A removable plug as claimed in any of claims 10 to 13, wherein the first closure portion is wider than the second closure portion.

15. A removable plug as claimed in any of claims 10 to 14, comprising an externally screw threaded portion;and optionally wherein the screw threaded portion is located adjacent to the first closure portion;and optionally wherein the screw threaded portion is located between the first and second closure portions.

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