A breather expulsion catch tank

Abstract

A breather expulsion catch tank 10 having a chamber 24 comprising: a bidirectional port 20; a breather vent 64; and a flow diverter 80a, 80b located adjacent to the vent 64. Oil (90, Fig. 8c) expelled

Description

TECHNICAL FIELD The present disclosure relates to a breather expulsion catch tank. Aspects of the invention relate to a vehicle drive unit comprising a breather expulsion catch tank in accordance with the present invention, and to a vehicle comprising a vehicle drive unit in accordance with the present invention. BACKGROUND During extreme articulation angles and drive cycles of a vehicle, particularly an off-road vehicle, it is possible for oil to be expelled with air from a vented unit, for example from an electric drive unit (EDU) of an electric vehicle. In particular, it has been found that oil can be expelled from an internal cavity of an EDU and travel up through a breather spigot and breather pipe in volumes of up to 60ml. The expelled oil creates the risk of blockages in the breather pipe, restricting the air flow to the EDU and therefore limiting the ability to balance the internal pressure of the EDU. 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 a breather expulsion catch tank, a vehicle drive unit comprising a breather expulsion catch tank and a vehicle comprising a vehicle drive unit, as claimed in the appended claims. The present invention relates to a breather expulsion catch tank comprising a flow diverter. According to an aspect of the present invention there is provided a breather expulsion catch tank, comprising a chamber comprising a bidirectional port, a breather vent and a flow diverter located adjacent to the breather vent. During extreme articulation angles and drive cycles of a vehicle, it is possible for oil to be expelled with air from a vented unit, for example from an electric drive unit of an electric vehicle. The invention allows the oil expelled with the air to collect temporarily within the chamber while allowing air from the unit to vent through a breather pipe connected to the breather vent. The flow diverter greatly reduces the likelihood that oil will reach the breather vent, even in extreme conditions, which could otherwise collect in the breather pipe and restrict correct venting of the unit, but still allows expelled air to vent. When the vehicle resumes a level articulation angle, any oil collected in the chamber can flow out of the catch tank back into the unit from where it was expelled. In an embodiment, the chamber comprises a floor which is configured to direct fluid towards the bidirectional port. Liquid which has temporarily accumulated in the chamber can flow back through the bidirectional port and back into the unit from which it was expelled and this effect can be enhanced by configuring the floor of the chamber to direct fluid towards the bidirectional port. In an embodiment, the floor of the chamber is at least partially inclined to direct fluid towards the bidirectional port. In an embodiment, the bidirectional port is in the floor of the chamber. By providing the bidirectional port in in the floor of the chamber, liquid which has temporarily accumulated in the chamber will flow back out of the chamber through the port and into the unit from which it was expelled. Optionally, the flow diverter is configured to prevent an uninterrupted flow path between the bidirectional port and the breather vent. By preventing an uninterrupted flow path, liquid which has accumulated within the chamber is prevented from entering the breather vent directly, for example if the liquid is agitated and is caused to splash as a result of movement of the vehicle, while still allowing gases to vent. Optionally, the flow diverter defines a flow path which changes direction along its length. The flow passage prevents an uninterrupted flow path of liquid out of the chamber through the breather vent, while still allowing gases to vent. In an embodiment, the flow diverter comprises a first internal wall so as to define a flow path between the first internal wall and an external wall of the catch tank. By defining a flow path between the first internal wall and an external wall of the catch tank, the likelihood of liquid reaching the breather vent is reduced. Optionally, the first internal wall is at least partially inclined to direct liquid flow in a direction away from the breather vent. By inclining the first internal wall, any liquid reaching the flow path between the first internal wall and the external wall will tend to flow back towards the collecting region of the chamber. In an embodiment, the flow diverter comprises a second internal wall so as to define a flow path between the first internal wall and the second internal wall. The further reduces the likelihood of liquid reaching the breather vent. The first internal wall may be located between the second internal wall and the external wall. In normal use, the first internal wall may be located above the second internal wall. Optionally, the second internal wall is at least partially inclined to direct liquid away from the breather vent. By inclining the second, outer internal wall, any liquid which reaches the flow path between the first internal wall and the second internal wall will tend to flow back towards the collecting region of the chamber. Optionally, the flow path between the first internal wall and the external wall is in communication with the flow path between the first and second internal walls. In an embodiment, the breather expulsion catch tank comprises an outlet in communication with the breather vent and wherein the bidirectional port and the outlet are aligned. Aligning the bidirectional port and the outlet allows the catch tank to be fitted into an existing venting pipe arrangement with minimal adjustment or alteration. In an embodiment, in use the breather vent is located at a level above the bidirectional port. According to another aspect of the invention, there is provided a vehicle drive unit comprising a breather expulsion catch tank in accordance with the invention. According to a further aspect of the invention, there is provided a vehicle comprising a vehicle drive unit in accordance with the invention. 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 from the front, one side and above of an embodiment of a breather expulsion catch tank in accordance with the invention; Figure 2 shows perspective view from the rear, the opposite side and below of the breather expulsion catch tank of Figure 1; Figure 3 shows a front view of the breather expulsion catch tank of Figure 1; Figure 4 shows a rear view of the breather expulsion catch tank of Figure 1; Figure 5 shows a vertical cross-section through the breather expulsion catch tank of Figure 1, looking in the direction of arrows V - V of Figure 1; Figure 6 is a vertical cross-section through the breather expulsion catch tank of Figure 1, corresponding to the view of Figure 5 but in a perspective view from the rear and below; Figure 7 shows a vertical cross-section through the breather expulsion catch tank of Figure 1, looking in the direction of arrows VII - VII of Figure 5; Figures 8(a) to (e) show vertical cross-section through the breather expulsion catch tank of Figure 1, looking in the direction of arrows V - V of Figure 1, in different orientations; and Figure 9 is a perspective view of the catch tank of Figure 1 fitted to an electrical drive unit for a road vehicle. DETAILED DESCRIPTION Figures 1 to 8 Illustrate an embodiment of breather expulsion catch tank 10 in accordance with the present invention and Figure 9 illustrates the catch tank 10 fitted in position on an electrical drive unit 12 for a road vehicle. The catch tank 10 comprises a housing formed from lower and upper housing portions 16, 18 which are sealingly secured together. As shown particularly in Figures 5 to 7, the housing includes a bidirectional inlet port 20, an outlet port 22 and a collection chamber 24 between the inlet and the outlet ports. In use, the inlet port 20 is connected to a breather spigot 14 of a vented unit such as an electric motor and the outlet port 22 is connected to atmosphere via a breather pipe 15. As an overview, it is intended that any liquid (typically oil) expelled with air from the vented unit collects in the collection chamber 24 and is subsequently able to flow back into the vented unit via the inlet port 20, while any expelled air is allowed to exit the catch tank via the outlet port 22 and flow along the breather pipe 15 to atmosphere. Collecting any expelled liquid in the chamber 24 reduces the risk of the liquid entering the breather pipe 15, which would otherwise restrict air flow to and from the vented unit and limit the ability to balance the internal pressure of the unit. Moreover, and as will be described, a diverter located at the top of the collection chamber causes any liquid which has accumulated in the chamber to follow a circuitous or serpentine path before it can exit from the outlet port 22 of the catch tank, which further reduces the likelihood of oil exiting out of the outlet port 22 and entering into the breather pipe. As best seen in Figures 2 to 7, the collection chamber 24 has an elongate base wall or floor 30, two opposed side walls 32, 34 extending upwardly from the opposite side edges of the base wall 30 and front and rear end walls 36, 38 at the opposite ends of the base wall 30. The collection chamber 24 communicates with the inlet port 20 via a connecting passage 40 located in the front end wall 36 adjacent to one of the side walls 32. As best seen in Figures 5 and 6, the base wall 30 is formed from two contiguous planar portions 30a, 30b which abut the front and rear end walls 36, 38 respectively, and as best seen in Figure 5 the portion 30b is inclined in order to direct liquid accumulated in the collection chamber 24 towards the connecting passage 40 and from there back through the inlet port 20. As best seen in Figure 7, the side wall 32 is inclined laterally outwardly with respect to the base wall 30 to direct liquid on the side wall 32 towards the base wall 30. The other side wall 34 has a first, lower portion 34a which is inclined laterally outwardly with respect to the base wall 30, a front upper portion 34b inclined upwardly and outwardly from an upper inclined edge 42 of the lowerwall portion 34a and a rear upper portion 34c which extends perpendicularly to the base wall 30 from a rear vertical edge 44 of the front upper portion 34b and from a horizontal upper edge 46 of the lower wall portion 34a, to direct liquid on the side wall 34 towards the base wall 30. As best seen in Figures 5 to 7, a first planar internal baffle 50 extends forwardly from the rear end wall 38 approximately parallel to the inclined rear base wall portion 30b and terminates short of the front wall 36 of the collection chamber 24, leaving a gap 52. A second planar internal baffle 56 located above the first baffle 50 extends rearwardly from the front end wall 36 of the collection chamber 24, slightly inclined towards the first baffle, and terminates short of the rear end wall 38, leaving a gap 58. The second baffle 56 is located inwardly of and below an upper wall 62 opposite the base wall 30 and an opening 64 is formed in the in the front end wall 36 adjacent to the upper wall 62 and the uppermost part of the side wall 34. A connecting passage 66 extends downwardly from the opening 64 and is formed from an inclined portion 68 which extends from the opening 64 on the outer face of the front end wall 36, which is contiguous with a horizontal portion 70 located immediately above the connecting passage 40 and is separated from it by a common wall 72. The end of the horizontal portion 70 remote from the inclined portion 68 communicates with a breather spigot 74 to which, in use, the breather pipe 15 is connected. A serpentine passage 80 is formed between the collection chamber 24 below the first baffle 50 and the opening 64 and forms a flow diverter upstream of the opening 64 for any liquids and gases in the collection chamber 24, i.e. any liquid or gas in the collection chamber 24 is diverted by the serpentine passage before it can reach the opening 64. The serpentine passage 80 is formed by a first portion 80a defined between the first and second baffles 50, 56, and whose upstream end communicates with the gap 52 between the free end of the first baffle 50. The downstream end of the first passage portion 80a is in communication with a second passage portion 80b defined between the second internal baffle 56 and the upper wall 62 of the housing, and whose downstream end communicates with the opening 64 in the front end wall 36. Consequently, an uninterrupted flow of gases and liquids from the collection chamber 24 out of the opening 64 is prevented. Instead, any liquid or gas in the collection chamber 24 below the first internal baffle 50 must pass through the gap 52 at the free end of the first baffle 50, along the first portion 80a of the serpentine passage 80 in a first direction shown by arrow 84, change direction at the free end of the second internal baffle 56 through approximately 180° as shown by arrow 86 and then travel along the second portion 80b of the serpentine passage in a second direction shown by arrow 88 before it can exit through the opening 64. However, the passage 80 still allows gases to pass relatively unhindered out of the collection chamber. Figures 8(a) to (e) show a series of vertical cross-sections through the catch tank, showing the change in orientation of the tank with the change of orientation of the vehicle in which the catch tank 10 is installed (and therefore the tank itself) from a normal orientation, to an inclined orientation and then back to a normal orientation. In Figure 8(a), the vehicle is on a flat, level surface. No oil expulsion occurs and air can pass freely into and out of the catch tank 10, with the airflow shown by the solid arrows. Figure 8(b) shows the catch tank 10 when the vehicle has tilted to an extreme articulation angle, where oil starts to be expelled from the electrical drive unit 12 into the collection chamber 24 of the catch tank, as shown by the shaded arrow, but as can be seen from the solid arrows, air can still pass freely into and out of the catch tank 10, as shown by the solid arrows. Figure 8(c) shows oil 90 expelled from the electrical drive unit 12 accumulating in the collection chamber 24 of the catch tank, in contact with the base wall 30 and the rear end wall 38, but as previously air can still pass freely into and out of the catch tank 10, as shown by the solid arrows. Figure 8(d) shows the catch tank 10 as the vehicle returns to its normal, level orientation, and shows the accumulated oil 90 draining out of the collection chamber 24 of the catch tank 10 back into the electrical drive unit 12 via the inlet port 20. As before, air can still pass freely into and out of the catch tank 10, as shown by the solid arrows. Finally, Figure 8(e) shows the catch tank when it has returned to the position of Figure 7(a). When the catch tank 10 is tilted from its normal position, oil expelled from the electrical drive unit 12 accumulates in the collection chamber 24 of the catch tank. However, it is unlikely that the oil will be able to exit the catch tank, as in order to do so it must make its way up through the flow diverter, i.e. the gap 52 between the first planar internal baffle, upwardly and along the first portion 80a of the serpentine passage 80, back along and up the second portion 80b of the serpentine passage 80 (having reversed its direction of flow at the junction of the two passage portions 80a, 80b), up the front end wall 36 and through the opening 64. Moreover, any oil which does make its way into the serpentine passage 80 will tend to flow back into the collection chamber 24 because of the inclination of the baffles 50, 52. However, the flow of air is relatively unhindered by the flow diverter, and is allowed to pass relatively freely into and out of the catch tank, irrespective of the orientation. 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 breather expulsion catch tank, comprising:a chamber comprising a bidirectional port, a breather vent and a flow diverter located adjacent to the breather vent.

2. A breather expulsion catch tank as claimed in claim 1, wherein the chamber comprises a floor which is configured to direct fluid towards the bidirectional port.

3. A breather expulsion catch tank as claimed in claim 2, wherein the floor of the chamber is at least partially inclined to direct fluid towards the bidirectional port.

4. A breather expulsion catch tank as claimed in claim 2 or claim 3, wherein the bidirectional port is in the floor of the chamber.

5. A breather expulsion catch tank as claimed in any of the preceding claims, wherein the flow diverter is configured to prevent an uninterrupted flow path between the bidirectional port and the breather vent.

6. A breather expulsion catch tank as claimed in claim 5, wherein the flow diverter defines a flow path which changes direction along its length.

7. A breather expulsion catch tank as claimed in claim 6, wherein the flow diverter comprises a first internal wall so as to define a flow path between the first internal wall and an external wall of the catch tank.

8. A breather expulsion catch tank as claimed in claim 7, wherein the first internal wall is at least partially inclined to direct liquid flow in a direction away from the breather vent.

9. A breather expulsion catch tank as claimed in claim 7 or claim 8, wherein the flow diverter comprises a second internal wall so as to define a flow path between the first internal wall and the second internal wall.

10. A breather expulsion catch tank as claimed in claim 9, wherein the second internal wall is at least partially inclined to direct liquid away from the breather vent.

11. A breather expulsion catch tank as claimed in any of claims 7 to 10, wherein the flow path between the first internal wall and the external wall is in communication with the flow path between the first and second internal walls.

12. A breather expulsion catch tank as claimed in any of the preceding claims, comprising an outlet in communication with the breather vent and wherein the bidirectional port and the outlet are aligned.

13. A breather expulsion catch tank as claimed in any of the preceding claims, wherein in use the breather vent is located at a level above the bidirectional port.

14. A vehicle drive unit comprising a breather expulsion catch tank as claimed in any of the preceding 5 claims.

15. A vehicle comprising a vehicle drive unit as claimed in claim 14.10

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