Filler element for an electric drive unit

Abstract

Aspects of the present invention relate to a filler element (50a, 50b) configured to occupy an interspace (20) of an electric drive unit (1). The filler element (50a, 50b) reduces the volume of the interspace (20) in which oil can collect, such that the volume of oil within the oil pickup channel (32) can be increased.

Description

[0001] FILLER ELEMENT FOR AN ELECTRIC DRIVE UNIT

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a filler element for an electric drive unit. Aspects of the invention relate to a filler element, an electric drive unit for a vehicle, a vehicle comprising the electric drive unit, and a method of assembling an electric drive unit.

[0004] BACKGROUND

[0005] It is known to provide an Electric Drive Unit (EDU) that provides motive power to move an Electric Vehicle (EV) forwards and backwards. The electric drive unit has a housing encapsulating various components of the electric drive unit. Several of these components require a supply of oil to prevent wear and ensure continued smooth operation of the moving parts.

[0006] The housing is capped by a pair of opposing end plates at each end of the electric drive unit. The end plates include a series of structural ribs that help provide structural support, howeverthe ribs have the knock-on effect of forming a relatively large interspace between the end plate and the adjacent bulkhead of the housing. During vehicle inclination, oil exits an oil pickup channel and collects in this interspace. The volume of oil contained in the oil pickup channel can thereby be lower, which can reduce the maximum flow rate of oil through the oil supply system.

[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] Throughout the summary of the invention, description and claims the terms front, rear, left, right, upper and lower are defined with reference to their normal use in the description of a forward facing upright standing vehicle. It follows that features of the invention are described in relation to a vehicle such that, for example, front features are those closer to the front of the vehicle than rear features and upper features are those closer to the top of the vehicle than lower features.

[0010] Aspects and embodiments of the invention provide a filler element, an electric drive unit for a vehicle, a vehicle comprising the electric drive unit, and a method of assembling an electric drive unit as claimed in the appended claims.

[0011] According to an aspect of the present invention there is provided a filler element configured to occupy an interspace of an electric drive unit having a housing, the interspace defined between an internal feature of the electric drive unit and an end plate of the housing, the filler element comprising: a body having opposing sides, one side configured to cooperate with an exterior surface of the internal feature of the electric drive unit and other side configured to cooperate with an interior surface of the end plate.

[0012] According to another aspect of the present invention there is provided a filler element configured to occupy an interspace of an electric drive unit having a housing, the interspace defined between an internal feature of the electric drive unit and an end plate of the housing, the filler element comprising: a body having opposing sides, one side configured to cooperate with an exterior surface of the internal feature of the electric drive unit and other side configured to cooperate with an interior surface of the end plate; and wherein the body is at least partially hollow.

[0013] With this arrangement, the filler element can displace a volume of oil within the interspace such that a greater volume of oil collects in the oil pickup channel of the electric drive unit. This can be particularly beneficial when the vehicle is inclined, when oil could otherwise collect in high volumes in the interspace.

[0014] The cooperation may be such that the filler element is configured to provide a gap between the first side of the filler element and the surface of the internal feature. The cooperation may be such that the filler element is configured to provide a gap between the second side of the filler element and the interior face of the end plate.

[0015] With this arrangement, the filler element occupies the space within the interspace to form a tortuous path for oil flow. This can restrict fluid flow, and in particular oil flow, through the interspace so as to maintain a greater volume of oil in an oil pickup channel of the electric drive unit when the vehicle is driven on inclined terrain.

[0016] Optionally, the filler element comprises an opening for the passage of a drive shaft of the electric drive unit therethrough.

[0017] Optionally, the opening may be an aperture, for example a central aperture. The centre of the aperture may align with the axis of the drive shaft passage.

[0018] Optionally, the filler element is impermeable to oil. This can increase the effectiveness of the filler element in reducing the occupiable volume of the interspace to oil.

[0019] Optionally, the filler element is formed of a non-metallic material. In contrast to the majority of the materials forming the electric drive unit, the filler element is non-structural and therefore a greater range of materials are available.

[0020] Optionally, the material may be plastic. The material may be polyethylene. Plastic can provide a low-density material that adequately fills the interspace whilst minimising any weight penalty. The compressibility of hollow bodied plastic elements can also help the filler element to conform to the shape of the interspace without completely restricting fluid flow, thereby reducing the required manufacturing tolerances.

[0021] Optionally, the filler element comprises one or more fasteners extending from an outer surface of the body of the filler element, each of the one or more fasteners being configured to engage with a respective aperture in the internal feature of the electric drive unit or the end plate of the housing.

[0022] Optionally, the body of the filler element comprises two or more mounting formations, each configured to engage an external fastener. Fasteners can be a particularly beneficial means of securing the filler element as they are discrete connection points that are easier to arrange so as not to prevent fluid flow, e.g. in comparison to the surface-to-surface connection required by adhesive.

[0023] Optionally, each mounting formation is a planar mounting surface for attaching a fastener head thereto.

[0024] The hollow body of the filler element can mean that attaching the fastener head to the filler element can be easier than forming an aperture or similar formation in the filler element. E.g. the hollow body may be more compliant than the end plate, and the manufacturing process of the hollow body may present difficulties in forming complicated formations such as blind holes.

[0025] Optionally, each of the planar mounting surfaces is normal to a longitudinal axis of the opening. There may be restricted access to the fasteners on the filler element as it is engaged to the end plate due to the substantially conformal shape of the filler element to the end plate. As a result of this, and the undulating shape of the filler that compliments the shape of the end plate, fasteners extending directly towards the end plate (i.e. having axes parallel to the longitudinal axis of the central axis) can be easier to insert.

[0026] According to yet another aspect of the invention, there is provided an electric drive unit for a vehicle, comprising: a housing having a main body and an end plate; an interspace defined between an internal feature of the electric drive unit and the end plate, an oil pickup channel in the main body, the oil pickup channel fluidically connected to the interspace via an oil drain aperture; and the filler element within the interspace.

[0027] Optionally, the filler element is configured to partially restrict fluid flow through the oil drain aperture. This can help reduce the oil flow rate exiting the oil pickup channel when the vehicle is inclined.

[0028] Optionally, the electric drive unit comprises a gap between the filler element and the internal feature, the gap extending between the oil drain aperture and an oil feed line to form a fluidic path therebetween.

[0029] The gap can provide a direct fluid path that returns oil to the oil pick up channel, with the filler element restricting the size of that fluid path to a desired level that provides a required flow rate of oil.

[0030] Optionally, the end plate comprises a plurality of ribs, and one of the opposing sides of the body of the filler element cooperates with a surface of each of the ribs of the plurality of ribs.

[0031] The shape of the end plate can be a required feature due to the required structural integrity of the end plate, and the desire to minimise weight. This increases the size of the interspace that can then allow significant levels of oil to pool if not restricted by the filler element. Optionally, the electric drive unit comprises an external fastener attached to the filler element, the external fastener having a shaft configured to engage with a blind hole in the end plate to fasten the filler element to the end plate.

[0032] The hollow body of the filler element can mean that it is easier to form a blind hole in the end plate rather than the filler element, whilst a fastener can provide various benefits over alternative solutions such as adhesive, including the absence of a rigid bond between the surfaces of the end plate and filler element.

[0033] According to a further aspect of the invention, there is provided a vehicle comprising the electric drive unit.

[0034] Optionally, the end plate is a rear end plate located at a rear end of the electric drive unit.

[0035] During vertical articulation of the vehicle up an incline, oil will tend to flow downwards and thereby pool in the interspace between the bulkhead and rear end plate unless restricted from doing so.

[0036] Optionally, the end plate is a front end plate located at a forward end of the electric drive unit.

[0037] During vertical articulation of the vehicle down an incline, oil will tend to flow downwards and thereby pool in the interspace between the bulkhead and forward end plate unless restricted from doing so.

[0038] Optionally, the electric drive unit comprises a front end plate and a rear end plate that each define respective interspaces with interior features of the electric drive unit. Each interspace may be occupied by a respective filler element.

[0039] Optionally, the oil drain aperture is located at a lower end of the electric drive unit. The lower position of the oil drain aperture can increase the volume of oil that can exit through the oil drain aperture as the vehicle travels up or down an incline.

[0040] According to a yet further aspect of the invention, there is provided a method of assembling the electric drive unit, comprising: attaching the filler element to the end plate; and subsequently attaching the end plate of the housing to the main body of the housing.

[0041] The filler element can be attached to the end plate first to ease manufacture. In particular, the filler element can be pre-attached to the end plate so that the end plate and filler element can be attached to the bulkhead as a single unit.

[0042] 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.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS

[0044] One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0045] Figure 1 shows a vehicle in accordance with an embodiment of the invention;

[0046] Figure 2 shows an electric drive unit;

[0047] Figure 3 shows a cross-section of the electric drive unit;

[0048] Figure 4 shows a close-up view of an interspace in the electric drive unit’

[0049] Figure 5 shows an oil supply system of the electric drive unit;

[0050] Figure 6 shows a filler element towards a rear end of the electric drive unit;

[0051] Figure 7 shows a cross-section of the filler element between a rear bulkhead and end plate of the electric drive unit;

[0052] Figure 8 shows a rear view of the filler element for positioning between the rear bulkhead and end plate;

[0053] Figure 9 shows a side view of the filler element;

[0054] Figure 10 shows a fastener arrangement for the filler element;

[0055] Figure 1 1 shows a filler element towards a front end of the electric drive unit;

[0056] Figure 12 shows a cross-section of the filler element between a front bulkhead and end plate of the electric drive unit;

[0057] Figure 13 shows a rear view of the filler element for positioning between the front bulkhead and end plate; and

[0058] Figure 14 shows a block diagram illustrating a method of assembling an electric drive unit.

[0059] DETAILED DESCRIPTION

[0060] A vehicle 100 in accordance with an embodiment of the present invention is described herein with reference to the Figure 1.

[0061] The vehicle 100 includes an electric drive unit (EDU) 1 that provides motive power to the vehicle 100. The vehicle 100 may be a battery electric vehicle (BEV) powered by one or more electric drive units 1 in the absence of an internal combustion engine, or may be a hybrid electric vehicle (HEV) having an electric machine and an internal combustion engine both arranged to drive wheels of the vehicle 100.

[0062] The EDU 1 includes various components housed within a housing 10 that are conventional to electric drive units such a rotor 2, stator 3, gears 4, and a central drive shaft passage 5 through which a drive shaft is insertable. The EDU 1 includes a plurality of bearings 6 that support smooth rotation of the moving parts of the EDU 1 , such as the rotor 2, gears 4 and shaft. To lubricate and reduce friction of the moving parts, the components of the EDU 1 are supplied with oil. For example, the oil supply system of the EDU 1 may include bearing feed lines that supply oil to the bearings 6. The housing 10 includes a main body 11 , a bulkhead 12a, 12b at each end of the housing 10 configured to contain the various components of the EDU 1 within the housing 10, and respective end plates 13a, 13b extending over each bulkhead 12a, 12b. Figure 3 shows the rear bulkhead 12a and rear end plate 13a in section, whilst Figure 12 shows the front bulkhead 12b and front end plate 13b.

[0063] The following discussion in relation to figures 2 to 9 will refer only to the rear bulkhead and end plate 12a, 13a, although it will be appreciated that the rear bulkhead and end plate 12a, 13a share many common features with the front bulkhead 12b and end plate 13b, as will be apparent from further discussion in relation to figures 11 to 13.

[0064] An interspace 20 is defined between the rear bulkhead 12a and the rear end plate 13a, such as shown in figures 3 and 4. The interspace 20 provides a passage for oil to flow from the various components and recirculate through the oil supply system of the EDU 1. For example, oil from the bearings 6 and associated system may be continuously fed through an oil feed line and subsequently flow into the interspace 20. The oil in the interspace 20 collects towards the lower end of the interspace 20 and can enter an oil pickup channel 32 through an oil drain aperture 33 defined in the rear bulkhead 12a (See figure 5). The oil can then be collected from the oil pickup channel 32 by an oil pickup tube 31 and recirculated to the components of the EDU 1. In the event that the vehicle 100 is inclined, oil can drain from the oil pickup channel 32, through the oil drain aperture 33, and collect in the interspace 20.

[0065] The size of the interspace 20 can define a volume of the oil that can pool in the interspace, ratherthan entering the oil pickup channel 32 for recirculation, and this pooling of the oil can create challenges in meeting necessary oil pickup rates to feed the oil supply system in certain situations, such as during vehicle articulation in which oil flows back through the oil drain aperture 33 into the interspace 20. The rear end plate 13a includes a plurality of strengthening ribs 15 that cause the body 14 of the rear end plate 13a to be spaced from the rear bulkhead 12a and thereby increase the size of the interspace 20.

[0066] To reduce the volume of the interspace 20, and prevent excessive oil collecting in it, the interspace 20 is occupied by a filler element 50a, such as shown in figures 6 to 10.

[0067] The filler element 50a includes a body 51 having opposing sides. A first side is configured with an exterior surface of the rear bulkhead 12a and a second, opposing, side is configured to cooperate with an interior face of the rear end plate 13a. By occupying the space within the interspace 20, the volume of oil able to collect within the interspace 20 can be reduced. This can help increase the volume of oil that collects in the oil pickup channel 32.

[0068] The cooperation of the filler element 50a to the rear bulkhead 12a and rear end plate 13a requires the filler element 50a to have an outer surface profile that closely conforms to the respective surfaces of the rear bulkhead and end plate 12a, 13a. As shown in Figures 6 to 9, the filler element 50a may include a series of undulations 55 configured to contour with the ribs 15 and other surface features of the rear bulkhead and end plate 12a, 13a. The filler element 50a is configured to occupy a majority of the interspace 20, at least at its lower side gravitationally) where oil would otherwise collect. For example, at least 90% of the interspace 20 may be filled. The filler element 50a may have a maximum thickness of at least 30 mm configured to extend between the bulkhead 12a and end plate 13a, and optionally at least 40mm. The undulations may have an amplitude that spans the majority of this thickness, for example at least 70% of the thickness, and optionally at least 80%. The filler element 50a may have a maximum width at least 70% the width of the housing 10 of the EDU 1 , and optionally of at least 80%.

[0069] In some examples, the cooperation is such that the filler element 50a provides a small gap between the first side of the filler element 50a and the exterior surface of the bulkhead 12a. The small gap may form a tortuous path for the flow of oil, such that the flowrate of oil through the interspace 20 is restricted. This provides a flow path for oil from the various components towards the lower end of the interspace 20 that is restricted such that backflow from the oil pickup channel 32 is reduced, thereby helping to maintain a greater volume of oil in the oil pickup channel 32 without closing off the oil flow path through the oil drain aperture 33. In addition, or alternatively, the cooperation may be such that the filler element 50a is configured to provide a similar small gap between the second side of the filler element 50a and the interior face of the end plate 13a. The filler element 50a may be arranged to partially restrict oil flow through the oil drain aperture 33, for example by partially occluding the oil drain aperture 33.

[0070] The filler element 50a is substantially non-load bearing and may be constructed to minimise weight. The filler element 50a may be at least partially hollow. For instance, the filler element 50a may be formed of a plastic or other non-metallic material. The filler element 50a may be blow moulded from polyethylene. The compressibility of hollow bodied plastic elements can help the filler element 50a to conform to the shape of the interspace 20 without completely restricting fluid flow. This can reduce the importance of manufacturing tolerances when constructing the filler element 50a. To minimise the available space for oil to collect, the filler element 50a may be impermeable to oil.

[0071] The filler element 50a includes various cut-outs and openings to maintain the operability of the EDU 1 . For instance, the filler element 50a may include an opening 52 that aligns with the central drive shaft passage 5 for the passage of the drive shaft and a cut out 53 providing a window for accessing an EDU busbar, such as shown in figure 8.

[0072] The filler element 50a may be directly attached to the rear bulkhead 12a or rear end plate 13a. The filler element 50a may be releasably connected to the rear bulkhead 12a or rear end plate 13a, for instance by one or more fasteners 61 . The body 51 of the filler element 50a may comprise one or more mounting formations

[0073] 60 to which the fastener 61 is engaged. In particular, a head 61 a of the fastener 61 may be fixedly attached to the filler element 50a, such as shown in figure 10. The mounting formation 60 may be a planar mounting surface defining a plane oriented normal to the axis of the central drive shaft passage 5, such that the fasteners

[0074] 61 have a longitudinal axis parallel to the axis of the central drive shaft passage 5. Alternatively, the fastener 61 may be integrally formed with the filler element 50a. The fasteners 61 are each configured to engage with a respective blind hole 62 in one of the rear bulkhead 12a or rear end plate 13a. Fasteners 61 provide discrete securing means that can be simple to assemble, may be releasable, and can reduce interreference between the outer surface of the filler element 50a and the outer surface of the rear bulkhead 12a or rear end plate 13a. This can be in contrast to alternative solutions such as adhesive that can require large areas of surface-to-surface contact to form a reliable attachment. In some examples, the blind hole 62 may be formed in the filler element 50a, such that the fastener 61 is attached or integral with the rear bulkhead 12a or rear end plate 13a. The fastener 61 may be a fir tree clip.

[0075] As previously discussed, a second filler element 50b may occupy an interspace 20 defined between the front bulkhead 12b and front end plate 13b. The second filler element 50b share many features in common with the first filler element 50a.

[0076] The second filler element 50b includes a body 51 having opposing sides. A first side is configured with an exterior surface of the front bulkhead 12b and a second, opposing side is configured to cooperate with an interior face of the front end plate 13b, such that the outer surface profile of the second filler element 50b closely conforms to the respective surfaces of the front bulkhead and end plate 12b, 13b.

[0077] The second filler element 50b may be dimensioned similarly to the first filler element 50a so as to be configured to occupy a majority of the interspace 20, as described previously. The second filler element 50b may have a maximum width that extends across the majority of the width of the housing 10, and have undulations having an amplitude that spans the majority of its thickness.

[0078] The second filler element 50b may be constructed of the same materials as the first filler element 50a and be at least partially hollow, e.g. the second filler element 50b may be blow moulded from polyethylene. The second filler element 50b may be releasably connected to the front bulkhead 12b or front end plate 13b by one or more fasteners 61 , such as shown in figure 10.

[0079] As with the first filler element 50a, the second filler element 50b may include a series of undulations 55 configured to contour with the strengthening ribs 15 and other surface features of the front bulkhead and end plate 12b, 13b. The second filler element 50b may be sized to provide a small gap adjacent the front bulkhead 12b and / or front end plate 13b. The second filler element 50b may include various cut-outs and openings to maintain the operability of the EDU 1 , such as an opening 52 for the drive shaft shown in figure 13.

[0080] Figure 14 illustrates a method 200 according to an embodiment of the invention. The method 200 is a method of assembling an electric drive unit 1 of a vehicle 100, such as the vehicle 100 illustrated in Figure 1 . The method 200 comprises a first step 201 of attaching the filler element 50a, 50b to the respective end plate 13a, 13b, followed by a second step 202 of attaching the end plate 13a, 13b to the main body 11 of the housing 10. In this case, the filler element 50a, 50b may be attached to the end plate 13a, 13b via one or more fasteners 61 such that the respective filler element 50a, 50b and end plate 13a, 13b form a single unit. This can ease assembly of the EDU 1 . In some alternative examples, the filler element 50a, 50b may be attached to the bulkhead 12a, 12b by one or more fasteners 61 , in which case the filler element 50a, 50b may be attached to the bulkhead 12a, 12b prior to attachment of the end plate 13a, 13b to the bulkhead 12a, 12b.

[0081] In the examples described above, the filler element 50a, 50b occupies an interspace 20 between a bulkhead 12a, 12b and an end plate 13a, 13b of the EDU. It will be appreciated that in some examples, the interspace 20 may be defined between an end plate 13a, 13b and an internal feature of the EDU other than the bulkhead 12a, 12b. For instance, the shape of the filler element 50a, 50b may be influenced by the outwardly extending portion of the bearing arrangement of the drive shaft such that the inner face of the interspace 20 may be partially formed by the bulkhead 12a, 12b and the outwardly extending portion of the bearing arrangement.

[0082] 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

CLAIMS1. A filler element configured to occupy an interspace of an electric drive unit having a housing, the interspace defined between an internal feature of the electric drive unit and an end plate of the housing, the filler element comprising: a body having opposing sides, one side configured to cooperate with an exterior surface of the internal feature of the electric drive unit and another side configured to cooperate with an interior surface of the end plate; and wherein the body is at least partially hollow.

2. The filler element of claim 1 , comprising an opening for the passage of a drive shaft of the electric drive unit therethrough.

3. The filler element of claim 1 or claim 2, wherein the filler element is impermeable to oil.

4. The filler element of any preceding claim, comprising one or more fasteners extending from an outer surface of the body of the filler element, each of the one or more fasteners being configured to engage with a respective aperture in the internal feature of the electric drive unit or the end plate of the housing.

5. The filler element of any preceding claim, wherein the body of the filler element comprises two or more mounting formations, each configured to engage an external fastener.

6. The filler element of claim 5, wherein each mounting formation is a planar mounting surface for attaching a fastener head thereto.

7. An electric drive unit for a vehicle, comprising: a housing having a main body and an end plate; an interspace defined between an internal feature of the electric drive unit and the end plate, an oil pickup channel in the main body, the oil pickup channel fluidically connected to the interspace via an oil drain aperture; and the filler element of any preceding claim within the interspace.

8. The electric drive unit of claim 7, comprising a gap between the filler element and the internal feature, the gap extending between the oil drain aperture and an oil feed line to form a fluidic path therebetween.

9. The electric drive unit of claim 7 or 8, wherein the end plate comprises a plurality of ribs, and one of the opposing sides of the body of the filler element cooperates with a surface of each of the ribs (15) of the plurality of ribs.

10. The electric drive unit of any one of claims 7 to 9, comprising an external fastener attached to the filler element, the external fastener having a shaft configured to engage with a blind hole in the end plate to fasten the filler element to the end plate.11 . A vehicle comprising the electric drive unit of any one of claims 7 to 10.

12. The vehicle of claim 1 1 , wherein the end plate is a rear end plate located at a rear end of the electric drive unit.

13. The vehicle of claim 1 1 , wherein the end plate is a front end plate located at a forward end of the electric drive unit.

14. The vehicle of any one of claims 11 to 13, wherein the oil drain aperture is located at a lower end of the electric drive unit.

15. Method of assembling an electric drive unit of any one of claims 7 to 10, comprising: attaching the filler element to the end plate; and subsequently attaching the end plate of the housing to the main body of the housing.

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