EDU coolant sump with spigot

Abstract

A coolant sump 104 for an electronic drive unit (EDU), such as for a vehicle, comprises at least one elongate spigot 112 extending from a body, the spigot comprising a proximal portion 116 extending f

Description

TECHNICAL FIELD The present disclosure relates to an electric drive unit (EDU) coolant sump having a spigot. Aspects of the invention relate to an EDU having a spigot, to a vehicle comprising an EDU having such a coolant sump, and to a method of assembling an EDU. BACKGROUND An electric drive unit (EDU) of a vehicle comprises mechanical and electronic components for accepting a drive current from an inverter and generating torque in one or more output shafts for driving road wheels, thereby causing the vehicle to move. A coolant, which can also act as a lubricant, is circulated within the EDU. A sump can be provided, into which the coolant drains. The sump can be a separate component that is attached to the EDU. Fluid connections between the sump and the interior of the EDU can be made by way or one or more spigots. 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 (EDU) coolant sump having a spigot, to a vehicle comprising an EDU having such a coolant sump, and to a method of assembling an EDU, as claimed in the appended claims According to an aspect of the present invention there is provided a coolant sump for an electronic drive unit, EDU, the sump comprising a body and an elongate spigot extending from the body, the elongate spigot comprising: a proximal portion extending from the body; a distal portion extending from the proximal portion, the distal portion being configured to receive an O-ring; and a shoulder disposed between the proximal portion and the distal portion for preventing, in use, movement of the O-ring from the distal portion onto the proximal portion. This arrangement may allow for cheaper manufacture of the spigot, and may also make it easier to install an O-ring prior to installing the sump. A cross-sectional area of the distal portion may be constant in a direction away from the shoulder towards a distal end of the distal portion of the spigot. The cross-sectional area of the distal portion may reduce along at least one region in a direction away from the shoulder towards a distal end of the distal portion of the spigot. This may make it easier to align the spigot with an aperture of the EDU into which the spigot is inserted during installation of the sump on the EDU. The at least one region may comprise a tapered lead-in portion at the distal end of the distal portion. The tapered lead-in portion may make installation of the sump easier. The distal portion may comprise at least one force-demould structure extending laterally from the distal portion, the force-demould structure being configured to retain, in use, an O-ring between itself and the shoulder, prior to installation of the sump to an EDU. This may reduce the likelihood of an O-ring falling off the spigot prior to installation of the EDU. The force-demould structure may comprises at least one circumferentially-extending rib. More generally, the distal portion and / or the force-demould structure(s) can have a shape, size, configuration and / or construction that allows the spigot to be withdrawn from a mould in a linear direction. For example, the force demould structure(s) can extend only a relatively small way from the surrounding surface of the distal portion, and / or have a tapered profile, allowing it / them to compress sufficiently to allow their movement through the mould during linear withdrawal of the spigot from the mould. The coolant sump may comprise a plurality of the spigots, the spigots extending parallel to each other. The parallel spigots may be easier to manufacture and / or install. According to a further aspect of the invention, there is provided an electronic drive unit, EDU, comprising: a housing comprising a receiving bore for receiving the or each spigot of a preceding aspect of the invention; the sump of a preceding aspect of the invention, wherein the or each spigot extends into a corresponding one of the at least one receiving bores such that the O-ring seals between a radially outer surface of the distal portion of the spigot and a radially inner surface of the receiving bore. The or each receiving bore may define: a further proximal portion extending inwardly from an outer surface of the housing; a further distal portion extending inwardly from the further proximal portion; a further shoulder disposed between the further proximal portion and the further distal portion for preventing, in use, movement of the O-ring along the receiving bore beyond the further proximal portion. The sump may comprise at least two of the spigots, and the spigots may extend parallel to each other. The spigots and receiving bores may respectively be configured such that, during assembly, as the sump and housing are brought together, the shoulder of at least one of the spigots enters its corresponding receiving bore before the shoulder or at least another of the spigots enters its corresponding receiving bore. The distal portion may be longer than the further proximal portion. According to a further aspect of the invention, there is provided a vehicle comprising the EDU of a preceding aspect. According to a further aspect of the invention, there is provided a method of assembling an electronic drive unit, EDU, according to a preceding aspect, the method comprising: positioning a coolant sump according to a preceding aspect relative to a housing of an EDU; and bringing the coolant sump and housing together; such that the shoulder of least one of the spigots enters its corresponding receiving bore before the shoulder or at least another of the spigots enters its corresponding receiving bore. An O-ring on at least one of the spigots may engage an inner surface of its corresponding receiving bore before the O-ring on at least another of the spigots engages an inner surface of its corresponding receiving bore. This may reduce the peak force required to install the sump. The method may comprise: positioning a coolant sump according to a preceding aspect relative to a housing of an EDU; bringing the coolant sump and housing together; and such that the distal portion of at least one of the spigot(s) is guided by contact with the further shoulder and / or the further distal portion, prior to engagement of the corresponding O-ring with the inner surface of its corresponding receiving bore. This may help with alignment of the spigot(s) during installation of the sump. According to a further aspect of the invention, there is provided a coolant sump for attachment to an electronic drive unit, EDU, the sump comprising: a body; an elongate spigot extending from the body, the elongate spigot being configured to receive an O-ring; a shoulder region surrounding disposed between the proximal portion and the distal portion for preventing, in use, movement of the O-ring from the distal portion to the proximal portion. 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 perspective view of a vehicle; Figure 2 shows detailed a side view of the EDU of the vehicle of Figure 1 during assembly; Figures 3 to 7 show a sequence of detailed vertical sections through the EDU of Figures 1 and 2, during assembly; Figure 8 shows a detailed vertical section through an EDU according to a further embodiment of the invention; Figures 9 to 12 show a sequence of detailed vertical sections through an EDU in accordance with a further embodiment of the invention, during assembly; Figures 13 and 14 show a sequence of detailed vertical sections through an EDU in accordance with a further embodiment of the invention, during assembly; Figure 15 shows a method of assembling an EDU, according to a further embodiment of the invention; and Figure 16 shows a method of assembling an EDU, according to a further embodiment of the invention. DETAILED DESCRIPTION A coolant sump for an electric drive unit (EDU) in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures 2 to 7. The coolant sump can be installed on an EDU, which in turn can be installed in a vehicle 200 as shown in Figure 1. With reference to Figure 2, there is shown an EDU 100 in the course of assembly. The EDU 100 comprises mechanical and electronic components for accepting a drive current from an inverter (not shown) and generating torque in one or more output shafts (not shown) for driving road wheels (not shown), thereby causing the vehicle 200 to move. To this end, the EDU 100 typically includes an electrical machine (e.g., a multi-phase electric motor, not shown), a reduction gearbox (not shown), and a differential gear (not shown). The specific functional components of an EDU, such as EDU 100, are well known to the skilled person, and will therefore not be described in detail. Figure 2 shows EDU 100 during an assembly step. The EDU 100 comprises a housing 102. A coolant sump 104 is attached to a lower region of the housing 102. The coolant sump 104 comprises a body 108. The body 108 is moulded, stamped, machined, additively manufactured, or otherwise formed from a suitable material or materials, such as aluminium alloy and / or a polymer, and defines an internal volume for holding coolant for circulation through the EDU. During operation, the EDU 100 generates heat due to, for example, friction and electrical machine winding losses. One way of removing such heat is to circulate a coolant within the EDU. The coolant can be, for example, oil that is used to lubricate moving parts such as gears within the gearbox and / or differential. The coolant is pumped around the EDU, where it absorbs heat generated by various components. The heated coolant is cooled by a heat exchanger, where the heat is rejected to the atmosphere or repurposed (e.g., for cabin heating) before the cooled coolant is returned to the EDU. The heat exchanger can be a separate component, or can be integrated into the housing 102 or the sump 104, by way of cooling fins (not shown) for example. Two elongate spigots 112 extend upwards from an upper wall 114 of the body 108. The spigots 112 can be integrally formed with the portion of the body 108 from which it extends, or can be separate components that are joined to that portion of the body 108 in any suitable manner, including welding, bonding, and / or the use of mechanical fasteners, for example. Figures 3-7 show a cross-section of one of the spigots 112 and a corresponding aperture. The other spigot 112 is similar, and will not be described separately. The spigot 112 includes a proximal portion 116 extending from the upper wall 114. The proximal portion 116 is circular in cross-section, and defines a tubular cylinder. Other cross-sectional shapes and longitudinal sectional profiles can be used in other embodiments. As best shown in Figure 3, the spigot 112 also includes a distal portion 118 extending from the proximal portion 116. A shoulder 120 is disposed between the proximal portion 116 and the distal portion 118. The shoulder 120 is for preventing, in use, movement of an O-ring 128 (shown in Figures 4 to 7 but omitted from Figure 3 for clarity) from the distal portion 118 onto the proximal portion 116, as described in more detail below. The shoulder 120 in Figures 3 to 7 extends generally radially, but other profiles can be used in other embodiments. The distal portion 118 is circular in cross section. A cross-sectional area of the distal portion 118 is constant along a first region 122 in a direction away from the shoulder 120 towards a distal end 124 of the distal portion 118. The cross-sectional area of the distal portion 118 can reduce along at least one region in a direction away from the shoulder 120 towards the distal end 124. For example, in the embodiment of Figures 3 to 7, the distal portion 118 comprises a region defining a tapered lead-in portion 126 at the distal end 124, the purpose of which is described in more detail below. The distal portion 118 is narrower adjacent to the shoulder 120 than the proximal portion 116. Where the spigot 112 is moulded, this allows the moulding of the spigot 112 without the need for moveable mould elements or further machining steps that are required if a groove (for example) is used for the O-ring 128. The housing 102 includes a receiving bore 130 for receiving the spigot 112. The receiving bore 130 can take any suitable form, but in general, will include at least one region defining a radially inner surface 132 for engaging an outer region of the O-ring 128, such that the O-ring 128 forms a seal between a radially outer surface 134 of the distal portion 118 of the spigot and the radially inner surface 132 of the receiving bore 130. In the embodiment of Figures 2 to 7, the receiving bore 130 defines a further proximal portion 136 extending inwardly from an outer surface 138 of the housing 102. The further proximal portion 136 includes a converging lead-in portion 110 that helps to compress the O-ring 128 during installation, as described in more detail below. The radially inner surface 132 is disposed within the further proximal portion 136. A further distal portion 140 extends from the further proximal portion 136. A further shoulder 142 is disposed between the further proximal portion 136 and the further distal portion 140. The further shoulder 142 prevents, in use, movement of the O-ring 128 along the receiving bore beyond the further proximal portion 136, as described in more detail below. Figures 3 to 7 show an assembly sequence in which the coolant sump 104 is installed onto the housing 102 of the EDU 100. In Figure 3, the O-ring 128 has not yet been installed onto the spigot 112. In Figure 4, the O-ring has been installed onto the spigot 112. Any necessary liquid sealant or lubricant can be applied to the O-ring 128 and / or the radially inner surface 132 of the receiving bore 130. The spigot 112 is generally laterally aligned with the receiving bore 130. The coolant sump 104 is moving upwards such that the distal end 124 of the spigot 112 enters the receiving bore 130. The tapered lead-in portion 126 reduces the diameter of the spigot 112 at the distal end 124, making it easier to align the spigot 112 with the opening of the receiving bore 130. It will be appreciated that, in other embodiments, the housing 102 can be moved towards (e.g., lowered onto) the coolant sump 104, orthe housing 102 and the coolant sump 104 can both be moved towards each other. In Figure 5, the coolant sump 104 continues to move upwards, until the distal end 124 of the spigot 112 engages the further shoulder portion 142 of the receiving bore 130. In Figure 5, the spigot 112 is slightly misaligned, so that it first engages the right-hand side (in the drawing) of the shoulder portion 142. The interaction of the tapered lead-in portion 126 with the tapered further shoulder 142 causes the spigot 112 to align with the receiving bore 130 as the coolant sump continues to move upwards. In Figure 6, the coolant sump 104 continues to move upwards, until the O-ring 128 engages the converging lead-in portion 110 at the entrance to the receiving bore 130. As the coolant sump 104 continues to move upwards, the O-ring 128 is compressed between the shoulder 120 on the outer surface of the proximal portion 116 and the converging lead-in portion 110 of the receiving bore 130. The lead-in portion eases the compression of the O-ring 128, reducing peak forces and reducing the risk of O-ring damage. In Figure 7, the coolant sump 104 has moved upwards into its final position relative to the housing 102. The O-ring 128 seals between the outer surface 134 of the distal portion 118 and the adjacent inner surface 132 of the further proximal portion 136. Bolts or other fixings (not shown) can be used to fix the sump 104 to the housing 102. In use, coolant (not shown) that has passed through the EDU 100 drains into the sump 104 through the spigot 112, as shown by arrow 144 in Figure 7. Coolant pools in the bottom ofthe sump 104 and is extracted through a sump outlet (not shown) and sent to a heat exchanger (not shown). In other embodiments, the coolant remains within the sump 104, where heat is extracted by, for example, cooling fins on an underside of the coolant sump 104. In the embodiment of Figures 2 to 7, the sump 104 has two of the spigots 112. One of the spigots 112 is used to allow coolant to drain into the sump, and the other is a breather pipe for allowing pressure equalisation between the sump and the interior of the EDU. In other embodiments, only a single spigot 112 is used. In yet other embodiments, the sump 104 has more than two of the spigots 112. Optionally, where there is more than one spigot, at least some of the spigots extend parallel to each other. This may assist with demoulding in the event the spigots 112 are moulded, as well as in assembly of the sump and housing when they are moved together in the same axial direction of the or each spigot. Optionally, the or each spigot 112 includes at least one force-demould structure that extends laterally from the spigot 112. For example, such a force-demould structure can extend laterally from the distal portion 118, the force-demould structure being configured to retain, in use, an O-ring near the shoulder, prior to installation of the sump 104 to an EDU 100. The distal portion 118 and / or the force-demould structure can have a shape, size, configuration and / or construction that allows the spigot to be withdrawn from a mould in a linear direction. For example, the force demould structure(s) can extend only a relatively small way from the surrounding surface of the distal portion, and / or have a tapered profile allowing it / them to compress sufficiently to allow their movement through the mould during linear withdrawal of the spigot from the mould. The material(s) from which the spigot is formed can impact the dimensions and profile of the force-demould structure. For example, a less-flexible and / or less compressible material may require the force-demould structure to be smaller and / or have a flatter profile to allow the spigot to be removed from the mould. The use of a force-demould structure may avoid the need for a complex mould with moveable parts that would be required to allow demoulding of a larger retaining structure. Figure 8 shows an embodiment of the spigot 112 including a force-demould structure in the form of a circumferentially extending rib 146. The rib 146 is generally triangular in cross-section. In use, the O-ring 128 is slid onto the spigot 112 past the rib 146. The rib 146 inhibits the O-ring 128 from sliding off the spigot 112 while in transit or storage before the sump 104 is attached to the housing 102. It also helps to ensure that the O-ring stays on the spigot 112 during disassembly of the sump from the housing during servicing. It will be appreciated the force-demould structure can take other forms. For example, instead a single rib 146, a plurality of circumferentially spaced-apart ribs can be provided. This may still impede movement of the O-ring 128 off the spigot 128, while reducing the resistance to withdrawal of the spigot 112 from the mould during manufacture, due to reduced surface area of the ribs relative to that arrangement shown in Figure 8. Yet other shapes can also be employed for the force-demould structures. Turning to Figures 9 to 12, there is shown a simplified part-sectional side view of an embodiment of a sump 204 and housing 202, according to an embodiment the invention. The sump 204 includes a first spigot 212 and a second spigot 312, each of the spigots 212, 312 being similar to the spigot 112 of previous embodiments, with like features of the spigots 112, 212, 312 being indicated by like reference signs. The EDU housing 202 is similar the EDU housing and has a first receiving bore 230 and a second receiving bore 330. Each of the receiving bores 230, 330 is similar to the receiving bore 130 of previous embodiments, with like features are indicated with like reference signs. The spigots 212, 312 and receiving bores 230, 330 are respectively configured such that, during assembly, as the sump 204 and housing 202 are brought together, the shoulder 120 of the first spigot 212 enters the further proximal portion 136 of its corresponding receiving bore 230 before the shoulder 120 of the second spigot 312 enters the further proximal portion 136 of its corresponding receiving bore 330. The effect of this configuration is that the O-ring 128 of the first spigot 212 is compressed as it enters its corresponding receiving bore 230 before the O-ring 128 of the second spigot 312 is compressed as it enters its corresponding receiving bore 330. For example, Figure 10 shows the O-ring 128 on the first spigot 212 about to be compressed, while the O-ring 128 on the second spigot 312 will not start being compressed until some time after the initial compression of the other O-ring is complete. In Figure 11, compression of the O-ring 128 on the first spigot 212 is complete, and the initial compression of the O-ring 128 on the second spigot 312 is about to start. Since the maximum insertion force for each spigot is generally reached during initial compression of the O-ring, staggering the compression of the O-rings can reduce the peak force required to join the sump 204 to the housing 202. For example, if multiple O-rings are initially compressed at the same time, the required force is the sum of the peak force for each of them. Staggering the compression of multiple O-rings results in a series of smaller force peaks rather than a large force peak due to summing of individual peaks. The staggering effect can be achieved in any suitable manner. In the example of Figures 11 to 14, the shoulders of the first and second spigots 212, 312 are disposed in different planes (see lines 400,402) to each other, while the entrances to the corresponding receiving bores 230, 330 are in the same plane as each other (see line 404). Figures 13 and 14 show another embodiment, in which the shoulders of the first and second spigots 212, 312 are disposed in the same plane as each other (see line 406), while the entrances to the corresponding receiving bores 230, 330 are in different planes to each other (see lines 408, 410). It will be appreciated that, in other embodiments, the shoulders are not in the same plane as each other and the entrances to the receiving bores 230, 330 are also not in the same plane as each other. In other implementations, more than two spigots can be employed. Any two or more of the spigots and their corresponding receiving bores can be configured such that, during assembly, as the sump and housing are brought together, the shoulder of at least one of the spigots reaches the further proximal portion of its corresponding receiving bore before the shoulder of at least another of the spigots reaches the further proximal portion of its corresponding receiving bore. In certain embodiments, the point at which the shoulder of a spigot reaches the further proximal portion of its corresponding receiving bore can be measured at an entrance to the receiving bore. Optionally, the further proximal portion can include a tapered lead-in portion that is designed to compress an O-ring as the corresponding spigot enters the receiving bore. In that case, the point at which the shoulderof a spigot reaches the further proximal portion of its corresponding receiving bore can be measured at a starting point of the tapered lead-in, or at a point along the tapered lead-in where an O-ring would first engage it during insertion of a spigot. The embodiments of Figures 2 to 7, 9 to 12, and 13 and 14, all employ a tapered lead-in portion at the entrance to the receiving bores 130, 230, 330. Optionally, the or each spigot 112, 212, 312 and its corresponding receiving bore 130, 230, 330 can be configured such that, as the spigot 112 enters the receiving bore 130, the distal portion 118 of the spigot 112 engages the further shoulder 120 before the O-ring 128 engages the radially inner surface 132 of the receiving bore 130 (or the surface of the lead-in portion of the receiving bore, if present). This ensures that the spigot 112 is at least partially centred within the receiving bore 130 before the O-ring 128 begins to compress. This may reduce the force required to initially compress the O-ring 128 and / or reduce the chance of damage to the O-ring 128 during installation. Referring to Figure 15, there is shown a method 500 of assembling an EDU according to an embodiment. Method 500 comprises: positioning 502 a coolant sump, such as coolant sump 104, relative to a housing, such as housing 102, of an EDU, such as EDU 100; and bringing the coolant sump and housing together 504; such that the shoulder (e.g., shoulder 120) of least one of the spigots (e.g., spigot 212) enters its corresponding receiving bore (e.g., receiving bore 230), before the shoulderof at least another of the spigots (e.g., spigot 312) enters its corresponding receiving bore 330. Optionally, the O-ring 128 on at least one of the spigots engages an inner surface (e.g., radially inner surface 132), of its corresponding receiving bore (e.g., receiving bore 230) before the O-ring 128 on at least another of the spigots engages an inner surface of its corresponding receiving bore (e.g., receiving bore 330). Referring to Figure 16, there is shown a method 600 of assembling an EDU, such as EDU 100, according to an embodiment. Method 600 comprises: positioning 602 a coolant sump (e.g., coolant sump 104) relative to a housing (e.g., housing 102) of the EDU; and bringing the coolant sump and housing together 604; such that the distal portion of at least one of the spigot(s) (e.g., spigot 112, 212, 312) is guided by contact with a further shoulder (e.g., further shoulder 142) and / or a further distal portion (e.g., further distal portion 140), prior to engagement of the corresponding O-ring 128 with the radially inner surface (e.g., radially inner surface 132) of its corresponding receiving bore (e.g., receiving bore 130, 230, 330). The proximal portion 116 can be omitted, or can form part of the shoulder against which the O-ring 128 sits. 5 This may reduce the length of the spigot and allow for a shorter receiving bore. 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. 10

Claims

1 A coolant sump for an electronic drive unit, EDU, the coolant sump comprising a body and an elongate spigot extending from the body, the elongate spigot comprising:a proximal portion extending from the body;a distal portion extending from the proximal portion, the distal portion being configured to receive an O-ring; anda shoulder disposed between the proximal portion and the distal portion for preventing, in use, movement of the O-ring from the distal portion onto the proximal portion.

2. The coolant sump of claim 1, wherein a cross-sectional area of the distal portion is constant in a direction away from the shoulder towards a distal end of the distal portion of the spigot.

3. The coolant sump of claim 1, wherein a cross-sectional area of the distal portion reduces along at least one region in a direction away from the shoulder towards a distal end of the distal portion of the spigot.

4. The coolant sump of claim 3, wherein the at least one region comprises a tapered lead-in portion at the distal end of the distal portion.

5. The coolant sump of any preceding claim, wherein the distal portion comprises at least one force-demould structure extending laterally from the distal portion, the force-demould structure being configured to retain, in use, an O-ring between itself and the shoulder, prior to installation of the coolant sump to an EDU.

6. The coolant sump of claim 5, wherein the force-demould structure comprises at least one circumferentially-extending rib.

7. The coolant sump of any preceding claim, comprising a plurality of the spigots, the spigots extending parallel to each other.

8. An electronic drive unit, EDU, comprising:a housing comprising at least one receiving bore; andthe coolant sump of any preceding claim, wherein the or each spigot extends into a corresponding one of the at least one receiving bores such that the O-ring seals between a radially outer surface of the distal portion of the spigot and a radially inner surface of the receiving bore.

9. The EDU of claim 8, wherein the or each receiving bore defines:a further proximal portion extending inwardly from an outer surface of the housing;a further distal portion extending inwardly from the further proximal portion;a further shoulder disposed between the further proximal portion and the further distal portion for preventing, in use, movement of the O-ring along the receiving bore beyond the further proximal portion.

10. The EDU of claim 9, wherein the spigots and receiving bores are respectively configured such that, during assembly, as the coolant sump and housing are brought together, the shoulder of at least one of the spigots enters its corresponding receiving bore before the shoulder or at least another of the spigots enters its corresponding receiving bore.

11. The EDU of claim 9 or 10, when dependent on claim 4, wherein the or each further shoulder in the or each receiving bore is tapered and wherein the tapered lead-in portion of the distal portion of the or each spigot engages the shoulder during assembly to centre the spigot within the receiving bore prior to compression of the O-ring between the radially outer surface of the distal portion of the spigot and the radially inner surface of the receiving bore..

12. The EDU of any one of claims 8 to 11, wherein the distal portion of the or each spigot is longer than the further proximal portion.

13. A vehicle comprising the EDU of any one of claims 8 to 12 or the coolant sump according to any one of claims 1 to 7.

14. A method of assembling an electronic drive unit, EDU, according to any one of claims 8 to 11 having multiple parallel spigots on the sump and multiple parallel receiving bores, the method comprising:positioning a coolant sump according to claim 7 relative to a housing of an EDU; and bringing the coolant sump and housing together;such that the shoulder of least one of the spigots enters its corresponding receiving bore before the shoulder of at least another of the spigots enters its corresponding receiving bore and the O-ring on at least one of the spigots engages an inner surface of its corresponding receiving bore before the O-ring on at least another of the spigots engages an inner surface of its corresponding receiving bore.

15. A method of assembling an electronic drive unit, EDU, according to claim 11, the method comprising: positioning a coolant sump according to claim 4 or any one of claims 5 to 7 when dependent on claim4 relative to a housing of an EDU; andbringing the coolant sump and housing together;such that the distal portion of at least one of the spigots(s) is guided into the further distal portion of the corresponding receiving bore by contact of the tapered lead-in portion of the spigot with the furthershoulder in the receiving bore, prior to engagement of the corresponding O-ring with the inner surface of the receiving bore.13

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