Drain aperture for fluid reservoir

Abstract

A housing part for a fluid reservoir, such as a vehicle oil sump, comprises a housing wall which defines an interior surface 24 of the fluid reservoir, and an opposing external surface of the fluid re

Description

TECHNICAL FIELD The present disclosure relates to a housing part for a fluid reservoir, the housing part comprising drainage features. Aspects of the invention relate to the housing part, a fluid reservoir comprising the housing part, and a vehicle. BACKGROUND Fluid reservoirs, such as oil sumps for machines and vehicles, usually have a drainage aperture which can be selectively opened by a user to drain fluid from the reservoir during maintenance activities. Typically, such fluid reservoirs are provided with a removable plug which screws into and seals the drainage aperture. The drainage aperture is usually provided at the lowest point of the reservoirto allow the reservoir to be fully drained in situ and, as a result, the features for retaining the plug typically protrude outwardly from the reservoir housing. This presents challenges in applications where packaging space is limited, for example. It is against this background that the invention has been devised. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a housing part for a fluid reservoir, a fluid reservoir comprising the housing part, and a vehicle as claimed in the appended claims. According to an aspect of the invention, a housing part for a fluid reservoir, such as an oil sump for a machine or vehicle, is provided. The housing part comprises a housing wall which defines an interior surface of the fluid reservoir and an opposing external surface of the fluid reservoir when arranged for use. The housing part further comprises a boss, or projection, which extends axially from the interior surface to a distal end. The boss may be integrally formed with the housing wall. The housing part further comprises a through-hole, or bore, which extends through the boss from the external surface to the distal end, the through-hole being configured to receive a plug, or stopper, which seals the through-hole when secured therewithin. The housing part further comprises an aperture which extends radially, or transversely, through the boss from the through-hole to an exterior surface of the boss to define a fluid flow path which extends from the exterior boss surface to the external surface of the fluid reservoir when the plug is removed. The aperture is positioned axially away from the distal end of the boss so that fluid collected within the housing part when in use can drain to a level below that of the distal end of the boss. Embodiments may comprise a plurality of the apertures equidistantly spaced around the boss. The aperture may take the form of a slot which extends circumferentially around the boss. For example, the slot may extend circumferentially around the boss further than it extends axially along the boss. The aperture may be positioned closer to the interior surface of the fluid reservoir than to the distal end of the boss. Positioning the aperture as close as possible to the interior surface will minimise the volume of fluid that cannot be drained when the reservoir is arranged for use. The through-hole may comprise a tapped portion for receiving a corresponding threaded portion of the plug. In such embodiments, the tapped portion may be continuous around the whole circumference of the through- hole. Accordingly, the aperture may be positioned axially between the tapped portion of the through-hole and the interior surface of the fluid reservoir so as to not interfere with the tapped portion. In some embodiments, the through-hole may define a shoulder for receiving a sealing member thereagainst. The shoulder may be positioned between the external surface of the fluid reservoir and the aperture. In embodiments, the boss may comprise a frustoconical portion which tapers towards the distal end. Additionally or alternatively, the exterior boss surface may define a guide channel which extends axially from the distal end of the boss to the aperture. Such a guide channel is configured to guide fluid over the boss towards the aperture. It will be appreciated that preferred and / or optional features of one aspect of the invention may be incorporated alone or in appropriate combination in other aspects of the invention also. 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 schematic view of a vehicle according to an embodiment of the invention; Figure 2 shows a perspective cross-sectional view of a fluid reservoir according to an embodiment of the invention; Figure 3 shows a drain arrangement of the fluid reservoir shown in Figure 2; Figure 4 shows a cross-sectional view of the drain arrangement shown in Figure 3; Figure 5 shows a perspective cross-sectional view of the drain arrangement shown in Figures 3 and 4. DETAILED DESCRIPTION In general terms, embodiments of the invention provide a fluid reservoir housing part which comprises an internally projecting boss arranged to receive a plug and to allow the reservoir to drain when the plug is removed. The boss comprises a primary through-hole that is axial and configured to receive the plug, and one or more secondary apertures which extend through the side walls of the boss. When inserted into the through-hole, the plug seals against a shoulder surface so that flow paths to the exterior via the primary through-hole and the secondary apertures are blocked. When the plug is removed, fluid is free to flow from within the reservoir to the exterior through both the primary through-hole and the secondary aperture / s. As the reservoir drains, the fluid level drops below the opening of the through-hole. However, the secondary apertures are arranged nearer to the interior surface of the reservoir to allow the remaining fluid to drain therethrough. Providing the plug receiving features in an internally projecting boss means that the plug protrudes less, if at all, from the exterior of the reservoir housing when fully inserted. As a result, the packaging space required is reduced and the risk of damage to the plug and drain features is reduced. This is particularly beneficial in the context of vehicle oil sumps where the exterior of the oil sump defines the ground clearance of the vehicle. The secondary apertures allow the reservoir to be fully drained in situ, even though the opening of the primary drainage hole is internally vertically offset away from the bottom of the reservoir. To provide context for the invention, Figure 1 shows a vehicle 10 comprising a fluid reservoir 12 in the form of an oil sump. The oil sump 12 is mounted to define part of the underside of the vehicle and is arranged to collect used oil from other components of the vehicle. Figure 2 shows a cross-sectional view of a fluid reservoir 12 such as the one shown in Figure 1. The fluid reservoir 12 comprises two housing parts, a first housing part 14 and second housing part 16, which are joined together along weld flanges 18 to define an internal volume 20 for containing oil. In the example shown, the first housing part 14 forms the bottom part of the assembly and the second housing part 16 forms the top part of the assembly so that oil collects in the first (or lower) housing part 14 when the reservoir 12 is arranged for use. The fluid reservoir 12 comprises an inlet through which oil can be delivered to the internal volume and an outlet through which oil can be removed from the internal volume for recirculation to other components of the vehicle 10. Each of the housing parts 14, 16 comprises a housing wall 22 which defines an interior surface 24 of the fluid reservoir 12 and an opposing external surface 26 of the fluid reservoir 12. As shown, the lower housing part 14 also comprises a drain arrangement 28 which is configured for receiving a corresponding plug 30 (shown in exploded view away from the housing parts). Generally, the drain arrangement 28 is configured to allow fluid to drain from the reservoir 12 when the plug 30 is removed and to seal when the plug 30 is fully inserted to prevent fluid from leaking out of the reservoir 12. The drain arrangement 28 will now be described in more detail with reference to Figures 3 to 6. Figure 3 shows a close up view of the drain arrangement 28 in the lower housing part 14. As shown, the drain arrangement 28 comprises a boss 32, or projection, which extends upwardly away from the interior surface 24 of the lower housing part 14 (having regard to the orientation of the lower housing part 14 when arranged for use). The boss 32 extends from a root end 34 adjoined to the interior surface 14 to a distal end 36 which is free and offset away from the interior surface 14, thereby defining a longitudinal axis 37 (shown in Figure 4) which is perpendicular to the interior surface 14. In other words, the boss 32 is configured to project axially from the housing wall 22 into the interior volume 20 of the reservoir 12 when the lower housing part 14 is assembled together with the upper housing part 16 and arranged for use. The boss 32 extends from the root end 34 to define a substantially cylindrical portion 38 adjacent to the interior surface 14 of the lower housing part 14 and a frustoconical portion 40 which tapers from the cylindrical portion 38 towards the distal end 36 of the boss 32. Accordingly, the diameter of the boss 32 at the root end 34 is larger than at the distal end 36. This boss shape is suitably stable but requires less material than a solely cylindrical boss. The drain arrangement 28 further comprises a through-hole 42 which extends through the boss 32 along the longitudinal axis 37 from the external surface 26 to the distal end 36. Accordingly, the through-hole 42 provides a path through which fluid can flow out of the reservoir 12 when the plug 30 is removed. The boss 32 and the through-hole 42 together define an inner boss surface 44 and an outer boss surface 46. As best seen in Figures 4 and 5, which show cross-sectional views of the drain arrangement 28, the through-hole 42 is configured to receive a corresponding plug 30 which seals the through-hole 42 when fully inserted. In this example, therefore, the through-hole 42 comprises a tapped portion 48 which is configured to receive a corresponding threaded portion 31 of the plug 30. The through-hole 42 further comprises a shoulder portion 50 which defines a recess 52 in the external surface 26 of the housing part 14 for receiving a head 33 of the plug 30. In this example, the shoulder portion 50 extends away from the longitudinal axis 37 so that the diameter of the recess 52 is larger than that of the tapped portion 48. Accordingly, the plug 30 may be fully inserted and secured within the drain aperture 28 by screwing the threaded portion 31 into engagement with the tapped portion 48 of the through-hole 42 until the plug head 33 tightly abuts against the corresponding shoulder portion 50 of the drain aperture 28. Hereon, this shoulder portion 50 may be alternatively referred to as the plug head abutment shoulder. The drain arrangement 28 further comprises an aperture 54 which extends through the boss 32 from the inner boss surface 44 to the outer boss surface 46. In other words, the aperture 54 extends radially through the boss 32 from the through-hole 42 to the outer boss surface 46. Accordingly, the aperture 54 and the through-hole 42 together provide a second path through which fluid can flow out of the reservoir 12 when the plug 30 is removed. The second path extends from the outer boss surface 46 to the external surface 26 of the fluid reservoir 12. The aperture 52 is positioned axially away from the distal end 36 of the boss 32 and, more particularly, near to the root end 34 of the boss 32 so that the aperture 52 is positioned closer to the interior surface 24 of the housing part 14 than to the distal end 36 of the boss 32. Therefore, as will be understood, the second path provides a means for fluid between the distal end 36 of the boss 32 and the interior surface 14 to drain out of the fluid reservoir 12 when the housing part 14 is arranged for use. In this example, there are four apertures 54 arranged equidistantly spaced around the longitudinal axis 37, although only one can be seen in Figures 3 and 5. In other examples there may be more or fewer apertures 54 to provide a suitable flow rate of liquid upon draining. For the purposes of the following description, the features of only one aperture 54 will be described since, in this example, each aperture 54 is the same. As seen, the aperture 54 takes the form of a slot which extends circumferentially around the longitudinal axis 37, thereby defining an upper slot edge 56 and a lower slot edge 58. That is to say, the dimension in the circumferential direction is larger than the dimension in the axial direction such that the aperture 54 extends circumferentially around the boss 32 further than it extends axially along the boss 32. As best seen in Figures 4 and 5, the slot 54 is positioned axially between the tapped portion 48 of the through-hole 42 and the interior surface 24 of the lower housing part 14. This positioning ensures that the threads in the tapped portion 48 are continuous and remain uninterrupted by the aperture 54. As a result, the strength of the screwed connection between the threaded portion 31 of the plug 30 and the tapped portion 48 of the drain aperture 28 is maximised and the risk of threads misaligning as the plug 30 is screwed in is reduced. As also shown in Figures 4 and 5, the through-hole 42 defines a further shoulder portion 60 extending radially away from the longitudinal axis 37 and positioned between the recess 52 for receiving the plug head 33 and the aperture 54. This further shoulder portion 60 (otherwise referred to as the seal shoulder) is configured to receive a sealing member 62 thereagainst which serves to provide a fluid tight seal between the drain arrangement 28 and the plug 30 when the plug 30 is fully inserted in the through-hole 42. The sealing member 62 may be fixedly coupled to the seal shoulder 60, or to the corresponding plug 30. Alternatively, the sealing member 62 may be provided as a separate component to position in place upon screwing in the plug 30. In this example, the sealing member 60 takes the form of a rubber O-ring. In other examples, the sealing member 60 may be provided on the plug head abutment shoulder 50. In any case, the sealing member 60 is provided axially between the external surface 26 of the lower housing part 14 and the aperture 54 so that both the first and second fluid flow paths from the internal volume 20 to the exterior of the reservoir 12 are sealed when the plug 30 is fully inserted and the reservoir 12 is arranged for use. As shown best in Figure 3, for each slot 54, the boss 32 comprises a corresponding channel 64 formed in the outer boss surface 46 which extends from the distal end 36 of the boss 32 to the slot 54. In other words, the outer boss surface 46 defines a channel 64 which extends axially from the distal end 36 of the boss 32 to the lower edge 58 of the aperture 54. More specifically, the channel 64 extends from the distal end 36 of the boss 32 to the lower slot edge 58 so as to define an axial circumferential surface 66, a radial circumferential surface 68, and two opposing side surfaces 70 which adjoin the axial and radial circumferential surfaces 66,68. The axial circumferential surface 66 extends axially from the distal end 36 of the boss 32 to the upper slot edge 56, i.e. so that the axial circumferential surface 66 is perpendicular to the interior surface 24 of the lower housing part 14, and is curved in the circumferential direction about the longitudinal axis 37 of the boss 32. The radial circumferential surface 68 extends in the radial direction from the lower slot edge 58 to the outer boss surface 46 and is substantially parallel to the interior surface 24 of the lower housing part 14. The radial circumferential surface 68 has a dimension in the circumferential direction that is the same as for the slot so that the channel 64 and the slot 54 are the same width in the circumferential direction. The opposing side surfaces 70 are parallel to each other such that the channel 64 has the same circumferential dimension as the slot 54 along its axial length. As will be understood, the channel 64 therefore serves to guide fluid from the distal end 36 of the boss 32 towards the slot 54 so that, when the plug 30 is removed and the lower housing part 14 is arranged for use, fluid between the distal 36 and root ends 34 of the boss 32 is encouraged to drain out of the fluid reservoir 12 via the second fluid flow path. In other examples, the radial circumferential surface 68 may be angled away from the root end 34 of the boss 32 in the radial direction away from the longitudinal axis 37 so that fluid which collects against the radial circumferential surface 68 flows downwardly towards the slot 54 under gravity when the housing part 14 is arranged for use. 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. A housing part for a fluid reservoir, the housing part comprising:a housing wall defining an interior surface of the fluid reservoir and an opposing external surface of the fluid reservoir;a boss extending axially from the interior surface to a distal end;a through-hole extending through the boss from the external surface to the distal end, the through-hole being configured to receive a plug which seals the through-hole;an aperture extending radially through the boss from the through-hole to an outer boss surface to define a fluid flow path extending from the outer boss surface to the external surface of the fluid reservoir when the plug is removed; whereinthe aperture is positioned axially away from the distal end of the boss.

2. A housing part according to claim 1, wherein the aperture takes the form of a slot extending circumferentially around the boss.

3. A housing part according to 2, wherein the slot extends circumferentially around the boss further than it extends axially along the boss.

4. A housing part according to any preceding claim, wherein the aperture is positioned closer to the interior surface of the fluid reservoir than to the distal end of the boss.5 A housing part according to any preceding claim, wherein the through-hole comprises a tapped portion for receiving a corresponding threaded portion of the plug, wherein the tapped portion is continuous.

6. A housing part according to claim 5, wherein the aperture is positioned axially between the tapped portion of the through-hole and the interior surface of the fluid reservoir.

7. A housing part according to any preceding claim, wherein the through-hole defines a shoulder for receiving a sealing member thereagainst.

8. A housing part according to claim 7, wherein the shoulder is positioned between the external surface of the fluid reservoir and the aperture.

9. A housing part according to any preceding claim, wherein the boss comprises a frustoconical portion which tapers towards the distal end.

10. A housing part according to any preceding claim, wherein the outer boss surface defines a guide channel which extends axially from the distal end of the boss to the aperture.

11. A housing part according to any preceding claim, comprising a plurality of the apertures equidistantly 5 spaced around the boss.

12. A fluid reservoir comprising the housing part according to any preceding claim.

13. A fluid reservoir according to claim 12, wherein the fluid reservoir is an oil sump.1014. A vehicle comprising the fluid reservoir of claims 12 or 13.

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