Fluid recirculation system for a vehicle

Abstract

A fluid recirculation system 201 for a vehicle comprising a powertrain 200 comprising an electric drive portion 210 comprising an electric machine 210M, the fluid recirculating system comprising: a fluid pump; and a fluid pick-up pipe 230, the fluid pick-up pipe comprising: a gallery inlet (230MA, see fig. 2(d)) configured to receive fluid from a fluid gallery 212 of the electric drive portion; a sump inlet 10 (232, see fig. 2(e)) configured to receive fluid from a fluid sump of the powertrain; and an outlet (234) configured to emit fluid from the fluid pick-up pipe to the fluid pump. Oil that has been moved between parts as the oil drains has the disadvantage of aerating the oil and deteriorating the efficiency of the cooling oil. Oil supplied directly to the oil pick up pipe rather than being drained reduces the amount of air and gasses within the oil. The pick up pipe may be in fluid connection with an inlet of the fluid pump wherein the fluid is drawn by the fluid pump from the fluid pick up via the outlet,

Description

TECHNICAL FIELD The present disclosure relates to a fluid recirculation system for a vehicle. Aspects of the invention relate to a fluid recirculation system for a vehicle, a vehicle and a method. BACKGROUND For vehicle powertrains comprising an Electric Drive Unit (EDU), it is known to provide a fluid recirculation system for lubricating and cooling the EDU. In some vehicles having an (EDU), a single fluid recirculation system may serve both an electric motor and a transmission. However, the cooling and lubrication requirements of the electric motor may require a higher flow rate than the cooling and lubrication requirements of the transmission. In this circumstance, the additional flow of fluid through the transmission can be detrimental to performance by increasing drag on rotating gears within the transmission, and aeration of the fluid due to unnecessary contact with the rotating gears. 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 fluid recirculation system for a vehicle, a vehicle and a method as claimed in the appended claims. In an aspect of the invention for which protection is sought there is provided a fluid recirculation system for a vehicle comprising a powertrain. The powertrain may comprise an electric drive portion. The electric drive portion may comprise an electric machine operatively coupled to a transmission. The fluid recirculation system may comprise a fluid pump. The fluid recirculation system may comprise a fluid pick-up pipe. The fluid pick-up pipe may comprise a gallery inlet. The gallery inlet may be configured to receive fluid from a fluid gallery of the electric drive portion. The pick-up pipe may have a sump inlet configured to receive fluid from a fluid sump of the powertrain. The pick-up pipe may have an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump. According to an aspect of the present invention there is provided a fluid recirculation system for a vehicle comprising a powertrain comprising an electric drive portion comprising an electric machine operatively coupled to a transmission, the fluid recirculating system comprising: a fluid pump; and a fluid pick-up pipe, the fluid pick-up pipe comprising: a gallery inlet configured to receive fluid from a fluid gallery of the electric drive portion; a sump inlet configured to receive fluid from a fluid sump of the powertrain; and an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump. Embodiments of the present invention have the advantage that fluid flowing through the fluid bypass conduit of the electric drive portion, bypasses the transmission and is fed directly to the fluid pick-up pipe instead of being expelled into the sump. This reduces aeration of the fluid. The present applicant has recognised that aeration of the fluid can occur for example due to the velocity at which the fluid is expelled from the bypass conduit into the sump, or due to contact between the fluid and one or more rotating gears of a transmission of the powertrain. It is to be understood that excessive aeration of fluid limits the amount of heat from the electric drive portion that can be dissipated by the fluid, thereby limiting performance of the electric drive portion. Embodiments of the present invention may reduce aeration thereby enhancing cooling of the electric drive portion. The gallery inlet may comprise a plurality of apertures or a single aperture. Optionally, the fluid recirculation system further comprises a fluid pump, wherein the outlet of the fluid pick-up pipe is provided in fluid communication with an inlet of the fluid pump wherein fluid may be drawn from the fluid pick-up pipe via the outlet thereof by the fluid pump. Optionally, the fluid recirculation system further comprises a fluid gallery provided in fluid communication with the gallery inlet of the fluid pick-up pipe. Optionally, the fluid recirculation system comprises a fluid pick-up pipe comprising: two flanges circumferentially arranged around a manifold portion thereby forming a channel encircling the manifold portion bounded by the two flanges and the manifold portion comprising at least one gallery inlet. Optionally, the fluid recirculation system comprises a fluid pick-up pipe comprising: a seal, or a plurality of seals circumferentially arranged around the manifold portion bounded by the two flanges. Optionally, the fluid recirculation system further comprises a heat exchanger. Optionally, the fluid is a coolant. In addition or instead the fluid may be a lubricant. The fluid may be a fluid arranged to provide one or both of cooling and lubrication of one or more portions of the electric drive portion. Optionally, the fluid is an oil. In a further aspect of the invention there is provided a vehicle powertrain comprising: an electric drive portion comprising an electric machine operatively coupled to a transmission; and a fluid recirculation system as defined above, the fluid recirculation system being arranged to supply a flow of fluid to the electric machine to lubricate and / or cool the electric machine, the fluid gallery arranged to divide the flow of fluid from the electric machine into at least a transmission flow and a bypass flow, and direct the bypass flow therethrough to the fluid pick-up pipe, bypassing the transmission. The fluid gallery may be positioned at least partly within the electric drive portion, such that as fluid flows through the fluid recirculation system, the flow is divided into flow which traverses the fluid gallery, and bypasses the transmission (bypass flow) and flow which enters the transmission (transmission flow). In this way, the transmission may receive less fluid flow than the electric machine. While only one bypass is described herein, in some examples, a fluid recirculation system may comprise multiple fluid galleries for dividing the flow into a plurality of bypass flows. In this case, the multiple fluid galleries may confluence prior to the fluid pick-up pipe, or at the fluid pick up pipe. Optionally the fluid gallery comprises an electric drive portion gallery provided by the electric drive portion. Optionally, the vehicle powertrain comprises a fluid recirculation system arranged to direct the transmission flow from the electric machine to the fluid pick-up pipe, via the transmission. Optionally, the volume of the transmission flow may be greater than or equal to the bypass flow. Optionally, the electric machine is directly fluidically connected to the fluid pick-up pipe via the fluid gallery, the fluid gallery being arranged to isolate the bypass flow from the transmission. Optionally, the fluid gallery comprises a transmission gallery provided by a housing of the transmission, the transmission gallery being arranged to isolate the bypass flow from the transmission. Optionally, the transmission gallery is fluidically coupled to a gallery inlet of the fluid pick-up pipe. Optionally, the transmission is in fluid communication with a sump inlet of the fluid pick-up pipe. In an aspect of the invention there is provided a vehicle comprising a powertrain as defined above. In a further aspect of the invention there is provided a method of recirculating fluid in a vehicle powertrain comprising: supplying a flow of fluid to an electric drive portion of the powertrain by means of a fluid recirculation system comprising a fluid pump and a fluid pick-up pipe, the electric drive portion comprising an electric machine operatively coupled to a transmission, the method comprising: causing fluid supplied to the electric drive portion to be directed to the electric machine; causing fluid to flow from the electric machine and be divided to form a plurality of flows comprising a transmission flow and a bypass flow, whereby the transmission flow arrives at a sump inlet, and the bypass flow arrives at a gallery inlet; and drawing fluid through the outlet of the fluid pick-up pipe by means of the fluid pump, thereby drawing fluid into a sump inlet and a gallery inlet such that the transmission flow and the bypass flow are combined. Optionally, the transmission flow is directed to the fluid pick-up pipe, via the transmission and collected in a fluid sump, thereby arriving at a sump inlet. Optionally, the bypass flow is directed to the fluid pick-up pipe, via a fluid gallery, bypassing the transmission, thereby arriving at a gallery inlet. In an aspect there is provided a method of cooling an electric drive portion of a vehicle powertrain comprising recirculating fluid in the form of a coolant and / or lubricant by the method of a preceding aspect. 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. 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 schematic representations of (a) a side-view of a known vehicle electric drive unit (EDU) comprising a transmission of a motor vehicle with asidewall of the EDU and transmission partially cutaway to show portions of an oil recirculation system, including a known oil pick-up pipe, as viewed from a leftside of a vehicle with respect to a forward-looking direction from the vehicle; (b) a view of the EDU from a rear of the EDU with the transmission removed, looking in a forward direction relative to the vehicle; (c) a side-view of the EDU with a sidewall of the EDU and transmission partially cut away to show portions of the oil recirculation system as viewed from a right side of the vehicle with respect to a forward-looking direction from the vehicle; and (d) a view of the oil pick-up pipe shown in (a) from below; Figure 2 shows schematic representations of (a) a side-view of an EDU comprising a transmission cooled by an oil recirculation system according to an embodiment of the present invention with a sidewall of the EDU and transmission partially cut away to show portions of the oil recirculation system; (b) a 3D view from above looking rearwardly of a portion of a pick-up pipe of the oil recirculation system; (c) a side view of the pick-up pipe as viewed looking rearwardly with a portion of the housing of the EDU and transmission cut away; (d) a 3D view of the pick-up pipe from above, (e) a view of the pick-up pipe from directly below, and (f) a side view of the sump conduit portion of the pick-up pipe, showing the sump inlet of the pick-up pipe; Figure 3 is a schematic representation of a portion of the oil recirculation system illustrated in Figure 2 showing a portion of the oil gallery provided in the EDU and transmission to illustrate a path of the oil gallery, the oil gallery being coupled to the pick-up pipe; and Figure 4 is a schematic illustration of a vehicle 200V having an oil recirculation system according to Figures 2-3. DETAILED DESCRIPTION A known oil recirculation system 101 of a motor vehicle is described herein with reference to the accompanying Figures 1(a)-(d). Figure 1 is a schematic illustration of a portion of a known powertrain 100 of a vehicle having an electric drive portion, in the form of an electric drive unit (EDU) 110, The EDU 110 has an electric machine 110M, illustrated schematically in Figure 1(c), and a transmission 190. The electric machine 110M has a rotor 110R and a stator 11 OS and is operatively coupled to the transmission 190. Oil supplied to the EDU 110 is first directed to the electric machine 110M which is cooled and lubricated by oil which passes through and / or around the rotor 11 OR. The oil passes through galleries in the stator 11 OS of the electric machine 110M. Oil leaving the electric machine 110M is mainly directed to the transmission 190 where it cools and lubricates rotating gears and other components within the transmission 190. However, the electric machine 110M generally requires a higher flow rate of oil for cooling and lubricating than does the transmission 190. This may result in an excess of oil which is not required by the transmission 190 but which is simply required to be recirculated and cooled. If all the excess oil passes through the transmission, it can act as a retarder on the rotating gears by creating drag and may promote aeration of the oil due to contact with the rotating gears. This can inhibit proper lubrication and cooling. Oil supplied to the electric machine 110M that is excess to requirements for cooling and lubrication of the transmission 190 is directed through an oil gallery 112 provided in the EDU and drains into a sump 120, which is provided in a lower region of the EDU 110 as shown in Figure 1(a)-(c). The oil gallery 112 drains into the sump via an oil gallery outlet 114 as shown in Figure 1(b). When a flow of excess oil bypasses the transmission 190 in this way, it reduces the effects of some known problems arising from allowing excess oil to flow into the transmission 190. However, oil draining into the sump 120 from the oil gallery outlet 114 is prone to contact with one or more moving parts of the transmission 190 such as rotating gears. As also shown in Figure 1(b) and (c), an oil pick-up pipe 130 is provided in the sump 120. The oil pick-up pipe 130 has a oil inlet aperture 132 through which oil may be drawn into the pick-up pipe 130 by means of an oil pump 140. The oil inlet aperture 132 is arranged at an end of the oil pick-up pipe 130 such that the oil inlet aperture 132 is downward-facing in use. Put another way, the oil inlet aperture 132 faces in a direction away from the electric machine 110M. The present applicant has recognised that contact between oil and moving parts as the oil drains to the sump 120 has the disadvantage that air and other gasses present in the environment in which the oil flows may become entrained in the oil. The present applicant has recognised that this causes a deterioration in the cooling efficiency of the oil and is therefore undesirable. It may also lead to an increased rate of deterioration of the oil due to the presence of oxygen in the air. A fluid recirculation system in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures 2(a)-(f). Like features of the powertrain 200 of Figure 2 to the known powertrain 100 of Figure 1 are shown with like reference numerals incremented by 100. In the present embodiment the fluid recirculation is an oil recirculation system, arranged to recirculate oil for the purpose of cooling and lubricating an EDU 210 of the powertrain 200. The oil may be a mineral oil, a synthetic oil, or a plant-derived oil. However, embodiments of the present invention are not limited to the recirculation of oil. Fluids other than oils may be recirculated in embodiments of the present invention. The fluid may be referred to as a coolant and / or a lubricant. As noted above, in the present embodiment the fluid used is an oil. Use of an oil has the advantage that the fluid may be used to lubricate as well as cool. Thus, the fluid, being an oil, may provide useful lubrication for the moving parts with which the oil comes into contact. The EDU 210 of the embodiment of Figure 2 comprises an electric machine 210M (obscured in Figure 2(a) by a housing of the EDU 210) that is operatively coupled to a transmission 290. The EDU 210 is cooled and lubricated in a similar manner to the EDU 110 of Figure 1. The flow of oil to the EDU 210, flows to the electric machine 210M to cool and / or lubricate the electric machine 210M. The flow of oil from the electric machine 210M is divided to form a plurality of flows comprising a transmission flow and a bypass flow. Oil flowing from the electric machine 210M may be under pressure and may optionally be divided and / or directed by means of galleries, pipework, flow splitters, valves or other known methods. The transmission flow, flows to the transmission 290 to cool and lubricate the transmission, thereafter draining into the sump 220. As illustrated in Figure 2(a), the flow of oil from the electric machine 210M that is excess to requirements for cooling and lubricating the transmission 290, i.e. the bypass flow, is directed to an oil gallery 212 for the purpose of bypassing the transmission 290. The oil gallery 212 is provided in the EDU 210 in a similar manner to the known powertrain 100 of Figure 1. However, instead of draining from oil gallery outlet 114 (Figure 1(b), (c)) into sump 120 as in the case of the known arrangement of Figure 1, the flow of oil from the gallery 212 is supplied directly to an oil pick-up pipe 230. The feature that oil is supplied directly to the oil pick-up pipe rather than being drained to a sump 220 and passing over multiple moving parts in its journey to the sump 220 reduces the amount of air and other gasses that become entrained in the oil. This in turn reduces deterioration of the cooling efficiency of the oil. The oil pick-up pipe 230 is illustrated in further detail in Figure 2(b)-(f). The pick-up pipe 230 is in the form of a conduit having a sump inlet 232 at one end as shown in Figure 2(e) and (f). The sump inlet 232 is arranged, in use, to be below the surface level of oil in the sump 220 and allow oil in the oil sump 220 to be drawn into a pick-up pipe sump conduit portion 230S of the pick-up pipe 230. A flow path of oil drawn from the oil sump 220 into the pick-up pipe sump conduit portion 230S via the sump inlet 232 of the pick-up pipe 230 is shown schematically in Figure 2(f). The pick-up pipe 230 also has a pick-up pipe outlet 234 shown in Figure 2(b) through which oil may flow out from the pick-up pipe 230. Oil drawn into the pick-up pipe 230 through the sump inlet 232 flows along the sump conduit portion 230S of the pick-up pipe 230. The sump conduit portion 230S is substantially oblong in crosssection. The sump conduit portion 230S is arranged to feed oil drawn from the sump 220 to a manifold portion 230M of the pick-up pipe 230 that has a discorectangular cross-sectional shape. That is, the cross-sectional shape is obround or ‘pill shaped’, being defined by a rectangular shape with semi-circular portions defining one pair of opposite edges. The manifold portion 230M of the pick-up pipe 230 has a gallery inlet preferably in the form of an aperture 230MA, or more preferably a plurality of apertures 230MA, through a wall of the manifold portion 230M around the manifold portion 230M. The manifold portion 230M is therefore arranged to receive a flow of oil therethrough from both the sump conduit portion 230S of the pick-up pipe 230 and from the gallery 212 via the gallery inlet apertures 230MA. Oil received by the manifold portion 230M of the pick-up pipe 230 is fed to an outlet conduit portion 230C of the pick-up pipe 230. The outlet conduit portion 230C of the pick-up pipe 230 terminates in a pick-up pipe outlet 234 that is provided in fluid communication with an oil pump. The oil pump is arranged to pump oil from the oil pick-up pipe 230 through the oil recirculation system 201. As illustrated in Figure 2(b), (d) and (e), the outlet conduit portion 230C of the pick-up pipe 230 is arranged to form an elbow 230E or bend through substantially 90 degrees. It is to be understood that in some embodiments other angles may be useful from zero to 180 degrees or more. Figure 2(e) is a view of pick-up pipe sump conduit portion 230S of the pick-up pipe 230 from below, looking substantially vertically upwards. The entirety of the pick-up pipe sump conduit portion 230S is not shown in Figure 2(b) or (c) for clarity. The sump inlet 232 of the pick-up pipe may be seen in Figure 2(e). As shown in Figure 2(e), the sump inlet 232 has a diameter and cross-sectional area that is less than that of the pick-up pipe sump conduit portion 230S immediately downstream of the inlet 232. This feature has the advantage that it further reduces aeration levels of oil being recirculated. As illustrated in Figure 2(b)-(d), the oil pick-up pipe 230 has two pairs of radial flange elements 230F1,230F2, and 230F3, 230F4, provided around the manifold portion 230M and arranged to facilitate the formation of a seal on each side of the gallery inlet apertures 230MA with respect to a longitudinal axis or centreline 230CL of the oil pick-up pipe 230. In the region of the manifold portion 230M the longitudinal axis or centreline 230CL of the pick-up pipe 230 is a notional line coincident with a centroid of a cross-sectional area of the manifold portion 230M parallel to an inner sidewall 230MW of the manifold portion 230M where the centreline 230CL passes through the manifold portion 230M. As illustrated in Fig. 2(b), the flange elements 230F2 and 230F3 are also circumferentially arranged around the manifold portion 230M to create a channel encircling the manifold portion 230M. The channel is bounded by the flange elements 230F2 and 230F3, and the manifold portion 230M comprising gallery inlet apertures 230MA. It is further illustrated in Fig. 2(c) that this channel advantageously brings the gallery outlet 214 of oil gallery 212 into direct fluid communication with the gallery inlet apertures 230MA, and does so in a way which negates the need for precision alignment of the gallery outlet 214 and any ofthe inlet apertures 230MA around the circumference ofthe manifold portion 230M. As illustrated in Fig. 2(e) flange element 230F4 comprises an extended component which abuts a housing ofthe transmission 290 upon installation, thereby determining alignment of gallery inlet apertures 230MA and gallery outlet 214 along the flow direction, i.e. along the longitudinal axis 230CL as illustrated in Fig. 2(c) and Fig. 3. A first pair of the two pairs of flange elements, 230F1 and 230F2, are provided upstream of the gallery inlet apertures 230MA with respect to an intended direction of oil flow from the sump conduit 230S to the outlet conduit 230C. A purpose ofthe first pair of flange elements, 230F1 and 230F2, is to enable the provision of an effective seal between the channel encircling manifold portion 230M and the sump 220. This advantageously prevents oil passing from the channel into the sump and prevents oil or air passing from the sump into the channel. Although the oil level in the sump 220 is ordinarily above the sump input 232, it is not necessarily above the level ofthe gallery outlet 214. Consequently, oil from the sump can only enter the pickup pipe at the sump input 232, and any air in the sump is prevented from entering the gallery inlet apertures 230MA. Hence, the flow of fluid cooling and lubricating the transmission 290 is separated from the flow of fluid bypassing the transmission via gallery 212 until they are combined in the pick-up pipe 230. A second pair ofthe two pairs of flange elements, 230F3 and 230F4, are provided downstream ofthe gallery inlet apertures 230MA. A purpose ofthe second pair of flange elements, 230F3 and 230 F4, is to enable the provision of an effective seal between the channel encircling manifold portion 230M and the external environment. This advantageously prevents the passage of oil from the channel encircling manifold 230M into the environment, and prevents air being drawn from the environment into the inlet apertures 230MA. Seal means in the form of an elastomeric ‘O’ ring 230FS is provided in each ofthe respective gaps between respective pairs of flanges 230F1-F2, 230F3-F4, in order to form a seal between the pick-up pipe 230 and an internal wall 290W of a housing ofthe transmission 290 in which the pick-up pipe 230 is provided. As indicated above, this prevents fluid, either liquid or gas, passing around the exterior ofthe pick-up pipe 230. As illustrated in Fig. 2(c), when the pick-up pipe is installed and sealed against the internal wall 290W, the channel encircling the manifold portion 230M forms a cavity 290C. Figure 3 is a schematic illustration of a flow path of oil to the pick-up pipe 230. As described above, the bypass flow, i.e. oil that is not required for cooling and lubricating the transmission 290, is directed to an oil gallery 212 provided in the EDU 210 in a similar manner to the known powertrain 100 of Figure 1. As shown in Figure 2(a) the oil gallery 212 has a first portion 212e formed in the EDU 210 that is coupled to a second portion 212t formed in a housing of the transmission 290. The second portion 212t formed in the housing of the transmission 290 terminates in the gallery outlet 214 (Figure 3) that is in fluid communication with the gallery inlet apertures 230MA formed in the sidewall 230MW of the manifold portion 230M of the oil pick-up pipe 230. Oil flowing out from the gallery outlet 214 is constrained to enter the manifold portion 230M of the pick-up pipe 230 by the channel encircling the manifold portion 230M bounded by flange elements 230F2 and 230F3 (Figure 2(b)) in combination with the seal means 230FS and internal wall 290W bounding the cavity 290C of the transmission 290 in which the pick-up pipe 230 is provided as illustrated in Figure 2(c). The first portion 212e of the oil gallery 212 may be referred to as an electric drive portion gallery 212e or electric drive unit gallery 212e. The second portion 212t of the oil gallery 212 may be referred to as a transmission gallery 212t. The transmission flow which has cooled and lubricated the transmission 290 drains into the sump 220 where it arrives at the pick-up pipe sump inlet 232. The bypass flow, which has bypassed the transmission arrives at the gallery inlet apertures 230MA of the pick-up pipe 230. A fluid pump (not shown) is in fluid communication with the outlet 234 of the pick-up pipe and draws a fluid flow from the pick-up pipe 230. This has the effect of drawing a fluid flow into the sump inlet 232 from the sump and into the gallery inlet apertures 230MA from the oil gallery 212 and thereby combines them. That is, the transmission flow and the bypass flow are combined in the pick-up pipe 230 and recirculated through the oil recirculation system 201. The oil recirculation system 201 may preferably comprise a heat exchanger and may optionally comprise an oil filter. It is to be understood that oil pick-up pipe 230 according to embodiments of the present invention may be formed from any suitable material or materials including metal such as steel or aluminium, metal alloy such as an aluminium-magnesium alloy or a plastics material such as an acrylonitrile butadiene styrene (ABS) plastics material, a polyether ether ketone (PEEK) plastics material, a polytetrafluoroethylene (PTFE) plastics material or any other suitable plastics material. Other materials may be useful instead or in addition. It is to be understood that an oil pick-up pipe 230 formed from a plastics material may be formed by injection moulding to form substantially the entire structure of the pick-up pipe 230 as a unitary structure. In some embodiments, the pick-up pipe 230 may be formed by injection moulding of two or more portions thereof that are subsequently joined together to form the pick-up pipe 230. For example, the pick-up pipe 230 may be formed in substantially two portions such as two halves that are subsequently joined, for example by welding or by means of an adhesive. For example, an upper portion may be formed as a unitary element by injection moulding and a lower portion may be similarly formed as a unitary element by injection moulding. The two portions may then be joined together. One or more further elements or portions may be introduced before or after joining the two portions. Other arrangements may be useful. Figure 4 is a schematic illustration of a vehicle 200V having an oil recirculation system according to Figures 2-3. Embodiments of the invention have the advantage that a cooling efficiency of oil used to cool the EDU 210 may be maintained and suffer a reduced amount of deterioration due to aeration thereof. Reduced aeration of the oil is achieved by directing oil which is excess to requirements for cooling of the transmission 290, to an oil pick-up pipe 230 that is directly connected to an oil gallery 212 through which the excess oil flows from the Electric Machine 210M to the pick-up pipe 230. This is in contrast to known arrangements in which excess oil not required for cooling of the transmission 190 is drained to a sump 120 via one or more portion of the powertrain having moving components, such as the transmission 190. It is to be understood that, by reducing aeration of oil, and thereby reducing deterioration of a cooling efficiency of the oil, deterioration in vehicle performance during the course of a given journey may be reduced. In some embodiments, a reduced amount of oil may be employed as a consequence, thereby reducing a weight of the vehicle 200V and a cost associated with vehicle operation. Furthermore, reduction in aeration of oil increases an expected service life of oil due to reduced oil degradation, including oxidation. 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 fluid recirculation system for a vehicle comprising a powertrain comprising an electric drive portion comprising an electric machine operatively coupled to a transmission, the fluid recirculating system comprising: a fluid pump; anda fluid pick-up pipe, the fluid pick-up pipe comprising:a gallery inlet configured to receive fluid from a fluid gallery of the electric drive portion;a sump inlet configured to receive fluid from a fluid sump of the powertrain; and an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump.

2. A fluid recirculation system according to claim 1, wherein the outlet of the fluid pick-up pipe is in fluid communication with an inlet of the fluid pump wherein fluid is drawn by the fluid pump from the fluid pick-up pipe via the outlet thereof.

3. A fluid recirculation system according to claim 1 or 2 further comprising the fluid gallery provided in fluid communication with the gallery inlet of the fluid pick-up pipe.

4. A fluid recirculation system according to any preceding claim wherein the fluid pick-up pipe comprises:two flanges circumferentially arranged around a manifold portionthereby forming a channel encircling the manifold portion bounded by the two flanges, the manifold portion comprising at least one gallery inlet.

5. A fluid recirculation system according to any preceding claim wherein the fluid is a lubricant and / or a coolant.

6. A vehicle powertrain comprising:an electric drive portion comprising an electric machine operatively coupled to a transmission; and a fluid recirculation system according to any preceding claim,the fluid recirculation system being arranged to supply a flow of fluid to the electric machine to lubricate and / or cool the electric machine, andthe fluid gallery arranged to divide the flow of fluid from the electric machine into at least a transmission flow and a bypass flow, and direct the bypass flow to the fluid pick-up pipe, bypassing the transmission.

7. A vehicle powertrain according to claim 6, wherein the fluid recirculation system is arranged to direct the transmission flow from the electric machine to the fluid pick-up pipe, via the transmission.

8. A vehicle powertrain according to claim 6 or 7, wherein the electric machine is directly fluidically connected to the fluid pick-up pipe via the fluid gallery, the fluid gallery being arranged to isolate the bypass flow from the transmission.

9. A vehicle powertrain according to any of claims 6 to claim 8 wherein the fluid gallery comprises a transmission gallery provided by a housing of the transmission, the transmission gallery being arranged to isolate the bypass flow from the transmission.

10. A vehicle powertrain according to claim 9 wherein the transmission gallery is fluidically coupled to a gallery inlet of the fluid pick-up pipe.

11. A vehicle powertrain according to any of claims 6 to 10, wherein the transmission is in fluid communication with a sump inlet of the fluid pick-up pipe.

12. A vehicle comprising a powertrain according to any one of claims 6 to 11.

13. A method of recirculating fluid in a vehicle powertrain comprising:supplying a flow of fluid to an electric drive portion of the powertrain by means of a fluid recirculation system comprising a fluid pump and a fluid pick-up pipe, the electric drive portion comprising an electric machine operatively coupled to a transmission, the method comprising:causing fluid supplied to the electric drive portion to be divided to form a plurality of flows comprising a transmission flow to the transmission and a bypass flow to the electric machine, wherebythe transmission flow arrives at a sump inlet of the pick-up pipe, andthe bypass flow arrives at a gallery inlet of the pick-up pipe; anddrawing fluid through the outlet of the fluid pick-up pipe by means of the fluid pump, thereby drawing fluid into a sump inlet and a gallery inlet such that the transmission flow and the bypass flow are combined.

14. A method of recirculating fluid in a vehicle powertrain according to claim 13, wherein the transmission flow is directed to the fluid pick-up pipe, via the transmission and collected in a fluid sump, thereby arriving at the sump inlet.

15. A method of recirculating fluid in a vehicle powertrain according to any of claim 13 or claim 14, whereinthe bypass flow is directed to the fluid pick-up pipe, via a fluid gallery, bypassing the transmission, thereby arriving at the gallery inlet.Application No: GB2317649.8Examiner: Mr Robin JonesClaims searched: 1-15Date of search: 23 May 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-15 GB2553808 A (ARRIVAL LTD ) - See whole document, in particular abstract and figure 5 showing plurality of internal inlets and outlets which may allow additional cooling loops within the motor. X 1-15 US 2015 / 258885 Al (TOYOTA MOTOR CO LTD) - See whole document, in particular paras. [0028-0029] and figures 2-4 showing oil bypass portion 32g. X 1-15 US 2016 / 033031 Al (ALLISON TRANSM INC) - See whole document, in particular figure 2 and paragraph [0052] describing a branch conduit 254 for providing flow to the by-pass valve 220. X 1-15 WO 2012 / 066876 Al (HONDA MOTOR CO LTD et al.) - See whole document WPI Abstract Accession No. 2012-G05618 and figure 2 showing bypass oil pathL4. X 1-15 JP2008281166A (HONDA MOTOR CO LTD) - See WPI Abstract Accession No.2008-N40025 figure 7 showing main oil path 70c 1 and bypass oil path 70c2. X 1-5 US 2015 / 369258 Al (DAIKIN IND LTD) - See whole document, in particular the abstract and figure 1 showing cooling pipes 40,41 for bypass cooling. X 1-5 US 2019 / 132991 Al (ABB SCHWEIZ AG) - See whole document, in particular paras. [0009-00014],X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPCB60K; H02K_______________________________________________The following online and other databases have been used in the preparation of this search report WPI, EPODOCInternational Classification:Subclass Subgroup Valid From B60K 0011 / 02 01 / 01 / 2006 B60K 0006 / 405 01 / 10 / 2007 B60K 0006 / 48 01 / 10 / 2007 H02K 0005 / 20 01 / 01 / 2006 H02K 0009 / 19 01 / 01 / 2006

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