Fluid pick-up pipe and method

Abstract

A fluid pick-up pipe 230 for a fluid recirculation system 201 of a vehicle, the vehicle comprising a powertrain comprising an electric drive portion, the fluid recirculation system comprising a fluid pump 240, the fluid pick-up pipe 230 comprising: a gallery inlet 233 configured to receive fluid from a fluid gallery 212 of the electric drive portion; a sump inlet 232 configured to receive fluid from a fluid sump 220 of the powertrain; an outlet 234 configured to emit fluid from the fluid pick-up pipe to the fluid pump; and a manifold portion 230M, a gallery fluid conduit 230G and a sump fluid conduit 230S, wherein the gallery fluid conduit provides fluid communication between the gallery inlet and the manifold portion, and the sump fluid conduit provides fluid communication between the sump inlet 232 and the manifold portion. The two conduits may be separated by a fluid tight rib.

Description

TECHNICAL FIELD The present disclosure relates to a fluid recirculation system for a vehicle. Aspects of the invention relate to a fluid pick-up pipe for a fluid recirculation system fora vehicle, a fluid recirculation system, a vehicle powertrain, a vehicle and a method. BACKGROUND It is known to provide a fluid recirculation system for lubricating and cooling a powertrain of a vehicle. In some vehicles having an electric drive unit (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 pick-up pipe, a fluid recirculation system, a vehicle powertrain, a vehicle and a method as claimed in the appended claims. According to an aspect of the present invention there is provided a fluid pick-up pipe for a fluid recirculation system of a vehicle, the vehicle comprising a powertrain comprising an electric drive portion comprising an electric machine operatively coupled to a transmission, the fluid recirculation system comprising a fluid pump, 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; an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump; a manifold portion in fluid communication with the outlet. Optionally, the fluid pick-up pipe further comprises: a gallery fluid conduit in fluid communication with the gallery inlet and the manifold portion; and a sump fluid conduit in fluid communication with the sump inlet and the manifold portion. Embodiments of the present invention have the advantage that the bypass flow, i.e. fluid flowing through the fluid gallery of the electric machine, may be fed directly to the fluid pick-up pipe thereby bypassing the transmission and not being expelled into the fluid sump. This reduces aeration of the fluid. The present applicant has recognised that aeration of the fluid can occur in known powertrains due to the velocity at which the fluid is expelled from the fluid gallery into the sump, or due to contact with 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 that can be dissipated by fluid, thereby limiting cooling of the electric drive portion. This in turn limits performance of the electric drive portion. Embodiments of the present invention may reduce aeration thereby enhancing cooling of the electric drive portion. It is to be understood that fluid which flows to the fluid pick-up pipe via the fluid gallery of the electric drive portion has already lubricated and cooled the electric machine. Fluid leaving the electric machine is mainly directed to the transmission (the transmission flow), where it cools and lubricates rotating gears and other components within the transmission before it drains into the fluid sump. However, the electric machine may require a higher flow rate of oil for cooling and lubricating than does the transmission. This leaves an excess of oil which is not required by the transmission but which is required to be recirculated and cooled. Optionally, the gallery fluid conduit and sump fluid conduit are defined at least in part by a rib element internal to the pick-up pipe, the internal rib element providing a fluid-tight wall separating the gallery fluid conduit and the sump fluid conduit. Optionally, the gallery fluid conduit comprises a gallery conduit outlet and the sump fluid conduit comprises a sump conduit outlet, wherein the gallery conduit outlet and sump conduit outlet are spaced apart from the outlet by the manifold portion. Optionally, the gallery conduit outlet is in line with the sump conduit outlet. Optionally, an angle between respective centrelines of the gallery fluid conduit and sump fluid conduit at the respective conduit outlets is in the range from zero degrees to 45 degrees. The feature that an angle between respective centrelines of the gallery fluid conduit and sump fluid conduit at the manifold portion is in the range from zero degrees to 45 degrees has the advantage of reducing churning of fluid in the pick-up pipe where the fluid flowing through the respective gallery and sump fluid conduits merge. The eddy currents and turbulence associated with churning can cause air already entrained in the fluid to form bubbles and aeration of the fluid reduces the amount of cooling the fluid is able to cause. Turbulence also increases friction thereby dissipating kinetic energy by converting mechanical energy into heat energy which is detrimental to a cooling system. It is to be understood that in some embodiments the fluid pick-up pipe establishes substantially parallel flow of fluid in the respective gallery and sump fluid conduits prior to entry of the respective fluid flows into the manifold portion. Optionally, an angle between respective centrelines of the gallery fluid conduit and sump fluid conduit at the respective conduit outlets is in the range from zero degrees to 20 degrees. Optionally, an angle between respective centrelines of the gallery fluid conduit and sump fluid conduit at the respective conduit outlets is in the range from zero degrees to 10 degrees. It is to be understood that the closer this angle is to zero, the lower the amount of churn of fluid in the manifold portion. Optionally, the gallery fluid conduit and sump fluid conduit are substantially parallel along at least a portion of a length thereof, said at least a portion terminating at the respective conduit outlets. Optionally, the gallery fluid conduit and sump fluid conduit are substantially parallel along at least a portion of their respective lengths, as measured from the respective conduit outlets, the portion being at least 50% of the shorter of the lengths of the gallery fluid conduit and sump fluid conduit. This feature has the advantage of allowing smoother mixing of fluid from the fluid gallery and sump once the fluid enters the manifold portion, since the flow of fluid in the respective conduits is more likely to be substantially parallel under laminar flow conditions. It is to be understood that, in order to reduce turbulent flow, matching of flow rates and flow direction of fluid flowing from the gallery fluid conduit and sump fluid conduit into the manifold portion is desirable. Optionally, the internal rib element extends at least 50% of the distance from the gallery inlet to the gallery outlet at the manifold portion. Optionally, the fluid pick-up pipe comprises a deflector wall adjacent to the gallery oil inlet, the deflector wall defining a boundary of the gallery conduit and comprising a curved portion presenting a concave surface toward the gallery oil inlet, and thereby being arranged to direct fluid entering the gallery conduit toward the manifold portion in a direction parallel to the sump conduit. This feature has the advantage that the gallery conduit bends smoothly to direct fluid flowing into the gallery conduit to flow in a direction parallel to a flow of oil along the sump conduit. It does this while minimising eddies and turbulent flow which can cause any already entrained air to form bubbles. Turbulence can also increase friction thereby dissipating kinetic energy by converting mechanical energy into heat energy which is detrimental to a cooling system. Optionally, a cross-sectional area of the sump inlet is less than a cross-sectional area of the sump fluid conduit. This feature has the advantage that aeration of fluid being drawn into the sump inlet is may be reduced. Optionally, a cross-sectional area of the gallery inlet is less than a cross-sectional area of the gallery fluid conduit. This feature has the advantage that it further reduces aeration levels of oil being recirculated. Optionally, the sump fluid conduit is longer than the gallery fluid conduit, the sump fluid conduit extending rearwardly away from the manifold portion a greater distance than the gallery fluid conduit. This enables the sump fluid inlet to be immersed in fluid within the sump of the powertrain. Optionally, the fluid pick-up pipe comprises a first seal and a second seal circumferentially arranged around the fluid pick-up pipe, wherein the gallery inlet is positioned between the first seal and the second seal. Optionally, the first seal and the second seal are provided on opposite respective sides of the gallery inlet with respect to a direction of flow of fluid from the sump inlet to the manifold portion. The feature of a dual seal arrangement has the advantage that a risk that air passes into the fluid recirculation system, either from within the sump or from the external environment, thereby causing fluid aeration, may be reduced. Optionally, a portion of the pick-up pipe carrying the first seal and the second seal is arranged to be inserted into a housing wherein the respective seal portions form a seal with an internal wall of the housing. Optionally, the first seal is inserted into the housing first, the first seal having a projected area normal to an insertion direction that is lower than a projected area of the second seal. This feature has the advantage that a risk of damage to the sump seal portion due to contact with a wall of the housing may be reduced. The first seal may comprise an ‘O’-ring. The second seal may comprise an ‘O’-ring. The respective seals may be substantially coaxial. In a further aspect of the invention there is provided a fluid recirculation system comprising: a fluid pump; and a fluid pick-up pipe according to another aspect. Optionally, 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. In a still 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 according to another aspect, 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 recirculation system comprising a 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. Optionally, the transmission flow is directed to the transmission. Optionally, at least a portion of the gallery is provided in the electric drive portion. Optionally, a portion of the gallery is provided in a transmission housing. Optionally, the at least a portion of the fluid bypass conduit provided by the gallery in the transmission housing is coupled to the gallery inlet of the fluid pick-up pipe. The portion of the gallery in the transmission housing may be coupled substantially directly to the gallery inlet of the fluid pick-up pipe. It is to be understood that the portion of the gallery provided in the transmission housing may be coupled substantially directly to the gallery inlet of the fluid pick-up pipe or via an intermediate component, such as an intermediate conduit, for example an intermediate conduit in the form of an adapter to adapt conduits of different diameters, an elbow such as a 90-degree elbow, or any other suitable intermediate component. The electric drive portion may be or comprise an electric drive unit (EDU). In an aspect of the invention there is provided a vehicle comprising a powertrain according to another aspect. In a further aspect of the invention there is provided a method of cooling and / or lubricating an electric drive portion of a powertrain by means of a fluid recirculation system having a fluid pump, 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; an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump; and a manifold portion in fluid communication with the outlet; the method comprising: directing fluid received through the gallery inlet to flow through a gallery fluid conduit; directing fluid received through the sump inlet to flowthrough a sump fluid conduit; directing fluid to flow into the manifold portion from the sump fluid conduit and from the gallery fluid conduit, thereby combining the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit in the manifold portion and emitting the combined flow at the outlet. Optionally, wherein the gallery fluid conduit and sump fluid conduit are defined at least in part by a rib element internal to the pick-up pipe, the internal rib element providing a fluid-tight wall separating the gallery fluid conduit and the sump fluid conduit. Optionally, an angle between respective centrelines of the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit is in the range from zero degrees to 45 degrees where the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit combine in the manifold. Optionally, the angle between respective centrelines of the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit is in the range from zero degrees to 20 degrees, or in the range from zero degrees to 10 degrees. Optionally, the gallery fluid conduit and sump fluid conduit are substantially parallel along at least a portion of a length thereof, said at least a portion terminating at the respective conduit outlets. In a still further aspect of the invention there is provided a fluid pick-up pipe for a fluid recirculation system of a vehicle, the vehicle having a powertrain comprising an electric propulsion machine, the fluid recirculation system having a fluid pump, the fluid pick-up pipe comprising: a gallery inlet configured to receive fluid from a fluid gallery of the electric machine; 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, wherein the fluid pick-up pipe is arranged to allow fluid received through the gallery inlet to flow through a gallery fluid conduit to a manifold portion of the fluid pick-up pipe and fluid received through the sump inlet to flowthrough a sump fluid conduit to the manifold portion of the fluid pick-up pipe, the gallery fluid conduit and sump fluid conduit being arranged wherein a flow direction of fluid in the gallery fluid conduit is substantially parallel to a flow direction of fluid in the sump fluid conduit where the respective conduits meet the manifold portion. It is to be understood that, if laminar flow is established in the respective gallery and sump fluid conduits, turbulent flow of fluid in the manifold portion may be reduced or eliminated if the flow direction of fluid from the respective conduits into the manifold portion is substantially parallel. This is at least in part because substantially no change in the direction of flow of the fluid will be required if the flow direction of fluid in the gallery fluid conduit is substantially parallel to the flow direction of fluid in the sump fluid conduit where the respective conduits meet the manifold portion. The fluid may be a coolant. Alternatively, or in addition the fluid may be a lubricant. The fluid recirculation system may be coolant recirculation system and / or a lubricant recirculation system. 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) of a motor vehicle comprising an electric motor and transmission with a sidewall of the EDU and transmission partially cut away to show portions of an oil recirculation system, including a known oil pick-up pipe, as viewed from a left side 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 comprising transmission, 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 according to embodiments of the present invention of (a) a sideview of an EDU comprising an electric motor and 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) is a schematic representation of a portion of the oil recirculation system 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; (c) is a schematic illustration of a 3D view of an oil pick-up pipe according to an embodiment of the present invention showing top and side surfaces, with respect to a normal upright orientation of a vehicle in which the pipe is installed; Figure 3 is a schematic illustration of an oil pick-up pipe according to an embodiment of the present invention viewed from below, with respect to a normal upright orientation of a vehicle in which the pipe is installed; Figure 4 is a schematic illustration of an oil pick-up pipe according to an embodiment of the present invention viewed from below, with respect to a normal upright orientation of a vehicle in which the pipe is installed, after slicing in a horizontal plane to remove a lower portion of the pick-up pipe and surrounding portion of the powertrain; Figure 5 is a schematic illustration of a vehicle oil recirculation system according to an embodiment of the present invention having an oil pick-up pipe according to an embodiment of the invention viewed from below with respect to a normal upright orientation of a vehicle in which the oil recirculation system is installed (drawing not to scale); Figure 6 is a schematic illustration of the oil pick-up pipe of Figures 2-5, corresponding to the view shown in Figure 4; Figure 7 is a schematic illustration of a vehicle 200V having an oil recirculation system according to Figure 5; and Figure 8 shows an oil pick-up pipe according to a further embodiment of the invention (a) as viewed from above at a similar plane to that of the illustration of Figure 6, i.e., a cross-sectional view of a lower portion of the pickup pipe, and (b) a plan view of the pick-up pipe as viewed from above. DETAILED DESCRIPTION A known oil recirculation system 101 of a motor vehicle is described herein with reference to the accompanying Figures 1(a) to (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 110R. The oil passes through galleries in the stator 110S 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 requires a higher flow rate of oil for cooling and lubricating than the transmission 190. This may result in an excess of oil which is not required by the transmission 190 but which is 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 8 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-b). Like features of the embodiment of Figures 2 to 4 to the known structure 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(a-b) 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. Figure 2(b), 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 is in fluid communication with a gallery oil inlet 233 of the oil pick-up pipe 230. Oil flowing out from the gallery 212 is constrained to enter the gallery oil inlet 233 of the pick-up pipe 230 by a first seal (230FS1) and a second seal (230FS2) circumferentially arranged around the fluid pick-up pipe either side of the gallery oil inlet 233 (see also Figure 3). A seal being formed by the first seal (230FS1) and the second seal (230FS2) between the internal wall of the transmission 290 in which the pick-up pipe 230 is positioned, and the pick-up pipe 230 itself. 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 oil inlet 233 of the pick-up pipe 230. A fluid pump 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 oil inlet 233 from the oil gallery 212. The fluid flowing into the sump inlet 232 flows along the sump fluid conduit 230S to the manifold portion 230M. The fluid flowing into the gallery oil inlet 233 flows along the gallery fluid conduit 230G to the manifold portion 230M. Hence, fluid flowing in the sump fluid conduit 230S and fluid flowing in the gallery fluid conduit 230G are combined in the manifold portion 230M. 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. Figure 2(c) is a schematic illustration of a 3D view of a fluid pick-up pipe 230 in accordance with an embodiment of the present invention as viewed from above and to one side. Figure 3 is a view of the pick-up pipe 230 from below. Figure 4 is a schematic illustration of the pick-up pipe 230 installed in a powertrain of a vehicle, the pick-up pipe 230 being viewed from below with a lower sidewall of a housing 230h of the pick-up pipe 230 cut away to reveal an internal structure of the pick-up pipe 230. As shown in Figure 2(c), the pick-up pipe 230 has a housing 230h defining an external surface of the pick-up pipe 230. The pick-up pipe 230 has a gallery oil inlet 233 arranged to be coupled to an oil gallery 212 (described below with respect to Figure 4). The pick-up pipe 230 also includes a sump inlet 232 (Figure 3) that is arranged, in use, to be below the surface level of oil in the sump 220 and to receive oil from the sump 220 provided in a lower region of the EDU 210 (described in further detail below with respect to Figure 5). The sump oil inlet 232 is provided proximate a free end of a sump conduit portion 230S of the pick-up pipe 230 that is arranged to project into the sump 220. The sump oil inlet 232 is arranged to face downwardly with respect to a normal upright orientation of a vehicle 200V in which the pick-up pipe 230 is installed (Figure 8). The sump conduit 230S may also be referred to as a (sump) inlet tract. Figure 4 shows a portion of an oil recirculation system 201 of a vehicle 200V in which the oil pick-up pipe 230 of Figure 2(c) and Figure 3 is installed. The vehicle 200V has a powertrain 200 that includes an electric drive unit (EDU) 210 comprising an electric machine 210M and a transmission 290. Figure 4 illustrates the pick-up pipe 230 as viewed from below in cross-section at a horizontal plane that divides the sump conduit 230S in half. Thus, an upper portion of the pick-up pipe 230 is visible in Figure 4. In the embodiment of Figures 2 to 6 the electric machine 210M is forward of the transmission 290 with respect to a longitudinal axis of the vehicle 200V in which the system 201 is installed. As shown in Figure 4, oil entering the pick-up pipe 230 via the gallery oil inlet 233 enters a gallery conduit 230G. The gallery conduit 230G may also be referred to as a bypass tract. The gallery conduit 230G is defined in part by a deflector wall 230GW which is positioned within the pick-up pipe 230 adjacent to the gallery oil inlet 233. The deflector wall 230GW comprises a curved portion thereby presenting a concave surface toward the gallery oil inlet 233. The deflector wall 230GW curves smoothly to direct fluid flowing into the gallery conduit 230G to flow in a direction parallel to a flow of oil along the sump conduit 230S. It is preferable to maintain a smooth curve and avoid discontinuities in the gallery conduit 230G boundaries to avoid boundary layer separation which can create eddies and turbulent flow conditions for fluid flowing in the gallery conduit. The parameters may vary due to viscosity, flow rate etc. in accordance with standard fluid mechanics practice. In one embodiment, flow entering the gallery oil inlet 233 may be brought parallel with the flow of oil along the sump conduit 230S by the deflector wall 230GW curving through an angle of substantially 90 degrees. As shown in Figure 4, oil entering the sump conduit through the sump oil inlet 232 also experiences a change in flow direction, a plane of the sump oil inlet 232 being substantially orthogonal to a longitudinal axis 230SA (a portion of which is indicated in Figure 4) of the sump conduit 230S. The sump conduit has a first portion 230SP that is substantially straight and projects into the sump 220. Oil flowing through the first portion 230SP, the flow direction of which is shown by arrows S, then encounters a parallel flow portion 230P of the pick-up pipe 230 where longitudinal axes of the sump conduit 230S and gallery conduit 230G are substantially parallel. The flow direction of oil in the gallery conduit 230G is indicated by arrows G. It should be understood that the parallel flow portion 230P can encompass curves in the pick-up pipe 230 in that the longitudinal axis remain parallel with respect to one another. The purpose of the parallel flow portion 230P is to stabilise the flow of oil in the respective sump and gallery conduits 230S, 230G in a substantially parallel direction. Channel parameters may be chosen in accordance with standard fluid mechanics principles to provide compatible flow velocity profiles for the gallery conduits 230S, 230G where they converge at their outlets 230SO, 230GO in the manifold portion 230M, This helps promote laminar flow, and minimise eddies (circular flow) and turbulent flow which can exacerbate issues with air entrainment in the fluid by causing bubbles to form from any gasses already entrained. Additionally, turbulent flow increases frictional forces leading to increased drag and kinetic energy dissipation which converts mechanical energy into heat and is unhelpful in a cooling system. In the parallel flow portion 230P a boundary between the conduits 230S, 230G is defined by a rib element 230R that provides an impermeable barrier to fluid flow between the conduits 230S, 230G. That is the rib element 230R forms a wall portion of each of the conduits 230S, 230G. The rib element 230R may be integrally formed within the pick-up pipe 230. The rib element 230R and parallel flow portion 230P terminate at a manifold portion 230M of the pick-up pipe 230 where the flow of oil through the sump conduit 230S merges with the flow of oil through the gallery conduit 230G. The point at which the gallery conduit 230G terminates at the manifold portion 230M may be referred to as a gallery conduit outlet 230GO. The point at which the sump conduit 230S terminates at the manifold portion 230M may be referred to as a sump conduit outlet 230SO. An end portion of the rib element 230R is adjacent one or both of the sump conduit outlet 230SO and gallery conduit outlet 230GO. The rib element 230R separates oil flows from different respective inlets 232, 233 while the individual oil flows are stabilised in the parallel portion 230P. It is to be understood that an angle between the flow direction of oil through the sump conduit 230S and the flow of oil through the gallery conduit 230G is substantially zero at the point at which the respective flows enter the manifold portion 230M, reducing a risk that eddy currents are established as the two flows from the conduits 230S, 230G combine in the manifold portion 230M. In the embodiment shown, the parallel portion 230P is arranged to bend the direction of flow of oil in the respective conduits 230S, 230G through a bend angle of substantially 60 degrees at a constant rate as a function of distance through the parallel portion 230P. In the present embodiment the bend is provided in order to accommodate vehicle packaging constraints while providing a parallel portion of sufficient length to at least partially stabilise respective fluid flows. It is to be understood that in some embodiments the bend angle may be greater than 60 degrees such as 70 degrees, 80 degrees, 90 degrees or any other suitable value for a given embodiment. In some alternative embodiments the bend angle may be less than 60 degrees such as 50 degrees, 45 degrees, 40 degrees or any other suitable value. A rate or bending may be variable as a function of distance in some embodiments, and is preferably chosen in line with standard fluid mechanics practice to minimise eddies and turbulence in the flow. In some embodiments the parallel portion 230P is substantially straight and does not bend. Oil received in the manifold portion 230M of the pick-up pipe 230 is fed to an outlet conduit portion 230C of the pick-up pipe 230 having an outlet 234 that is provided in fluid communication with an oil pump 240 (Figure 5). The oil pump 240 is arranged to pump oil from the oil pick-up pipe 230 through the oil recirculation system 201. The manifold portion 230M is between the outlet 234 and both the sump conduit and gallery conduit outlets 230S,230G. In this way the manifold portion 230M provides a confluence of the respective flows before the flows are emitted from the pick-up pipe 230. The outlet conduit portion 230C is of reduced diameter compared to a corresponding cross-sectional area of the manifold portion 230M normal to a direction of flow of oil entering the manifold portion 230M from the respective sump and gallery conduits 230S, 230G. Thus, a cross-sectional area of the manifold portion 230M reduces progressively in the direction of flow of oil therethrough in order to direct the oil through the outlet conduit portion 230C. The reduction in diameter of the manifold portion 230M may be equal around a circumference of the manifold portion 230M, that is the manifold portion 230M has a frustoconical shape and the outlet 234 is substantially circular. In an alternative embodiment, the manifold portion 230M may taper to an oval shaped outlet 234, such that the manifold portion 230M reduces in diameter at different rates across the cross section. This may give the manifold portion 230M a flattened appearance. Figure 5 is a schematic illustration of a portion of an oil recirculation system 201 arranged to recirculate oil to cool and lubricate an EDU 210, as viewed from below. Figure 5 illustrates both the housing 230h and internal conduits 230S, 230G of the pick-up pipe 230. As shown in Figure 5 and Figure 2(a-b) the gallery oil inlet 233 is coupled to an oil gallery 212 having a bypass inlet 210B arranged to receive oil from the electric machine 210M in a similar manner to that illustrated in Figure 1. The EDU 210 of the embodiment of Figure 5 has an electric machine 210M that is cooled and lubricated by oil in a similar manner to the EDU 110 of Figure 1. 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. The transmission flow, flows to the transmission 290 to cool and lubricate the transmission, thereafter draining into the sump 220. The oil gallery 212 has a first portion 212e formed in the EDU 210 and a second portion 212t formed in a housing of the transmission 290, the first portion 212e and the second portion 212t being coupled by means of a fluid-tight coupling. It is to be understood that, unlike the arrangement of Figure 1, the oil gallery 212 feeds the bypass flow directly into the pick-up pipe 230 via the gallery oil inlet 233 of the pick-up pipe 230. Thus, unlike the known arrangement of Figure 1, the oil is not first drained to the sump 220 but is fed directly to the pick-up pipe 230. The oil passes through the gallery oil inlet 233 and enters the gallery conduit 230G. Figure 6 is a schematic illustration of the oil pick-up pipe of Figures 2-5, as viewed in the same direction as the illustration of Figure 4. As illustrated in Figure 3, the oil pick-up pipe 230 has a pair of radial flange elements FS1, FS2 provided around the sump conduit 230S and gallery conduit 230G, which flanges are arranged to facilitate the formation of a seal on each side of the gallery inlet 233 with respect to a longitudinal axis or centreline 230SA of the sump conduit 230S of the oil pick-up pipe 230. A first flange element 230F1 is provided upstream of the gallery inlet 233 with respect to a direction of oil flow through the sump conduit 230S and a second flange element 230F2 is provided downstream of the gallery inlet 233. The purpose of the pair of flange elements 230F1-F2 is to enable the provision of an effective seal between the oil pick-up pipe 230 and internal volume of a housing of the transmission 290. Seal means in the form of a first seal element in the form of an elastomeric ‘O’ ring 230FS1 is provided circumferentially around the first flange element 230F1 whilst a second seal element in the form of an elastomeric O ring 230FS2 is provided circumferentially around the second flange element 230F2. Thus, the first seal element 230FS1 prevents oil passing directly from the gallery inlet 233 to the sump 220. Additionally, while the oil level in the sump 220 is ordinarily above the sump input 232 it is not necessarily above the level of the whole of the flange element 230F2, hence the first seal element 230FS1 also prevents oil or air passing directly from the sump 220 to the gallery inlet 233. The second seal element 230FS2 prevents oil passing directly from the gallery inlet 233 to the environment external to the pick-up pipe 230, and prevents ingress of air to the gallery inlet 233 from the external environment. It can be seen that the flange elements 230F1,230F2 are provided in a plane normal to the centreline 230SA of the sump conduit 230S. As viewed parallel to this centreline 230SA, a projection of the first flange element 230F1 to the plane of the second flange element 230F2 sits within the area of the second flange element 230F2, being of a reduced cross-sectional area. This ‘stepped-seal’ arrangement facilitates manufacture by reducing a risk of damage to one or both of the seal elements 230FS1,230FS2 during insertion of the pick-up pipe 230 into the housing of the EDU 210. As shown in Figure 4, the pick-up pipe 230 is provided with a mounting flange 230FM outboard of the first and second flange elements 230F1,230F2 to enable coupling of the pick-up pipe 230 to the housing of the EDU 210. Figure 7 is a schematic illustration of a vehicle 200V in which the oil recirculation system of Figure 5 is installed. Figure 8 shows an oil pick-up pipe according to a variation of the embodiment of Figures 2 to 6, (a) as viewed from above at a similar plane to that of the illustration of Figure 6, i .e., a cross-sectional view of a lower portion of the pick-up pipe, and (b) a plan view of the pick-up pipe as viewed from above. Like features are used for the embodiment of Figure 8 to those of the embodiment of Figure 6. The pick-up pipe is similar to that illustrated in Figures 2-6, except that it has an oblong sump conduit inlet 232 instead of a substantially round inlet. It is to be understood that the sump conduit inlet 232 may be of any suitable shape. 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. The following numerals may be used in conjunction with the figures of this application and substituted for the below text: 5000 Pick up inlet 5002 Pump inlet 6000 Inlet Tract 6002 Bypass Tract 8000 Inlet Tract 8002 Bypass Tract 8004 Parallel flow at merge point

Claims

1. A fluid pick-up pipe for a fluid recirculation system of a vehicle, the vehicle comprising a powertrain comprising an electric drive portion comprising an electric machine operatively coupled to a transmission, the fluid recirculation system comprising a fluid pump, the fluid pick-up pipe comprising:a gallery inlet configured to receive fluid from a fluid gallery of the electric machine;a sump inlet configured to receive fluid from a fluid sump of the transmission;an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump;a manifold portion in fluid communication with the outlet.

2. A fluid pick-up pipe according to claim 1 further comprising:a gallery fluid conduit in fluid communication with the gallery inlet and the manifold portion; anda sump fluid conduit in fluid communication with the sump inlet and the manifold portion and optionally, wherein the gallery fluid conduit and sump fluid conduit are defined at least in part by a rib element internal to the pick-up pipe, the internal rib element providing a fluid-tight wall separating the gallery fluid conduit and the sump fluid conduit.

3. A fluid pick-up pipe according to claim 1 or claim 2 wherein the gallery fluid conduit comprises a gallery conduit outlet and the sump fluid conduit comprises a sump conduit outlet, wherein the gallery conduit outlet and sump conduit outlet are spaced apart from the outlet by the manifold portion.

4. A fluid pick-up pipe according to claim 3 wherein the gallery conduit outlet is in line with the sump conduit outlet.

5. A fluid pick-up pipe according to any preceding claim wherein the gallery fluid conduit and sump fluid conduit are substantially parallel along at least a portion of a length thereof, said portion terminating at the respective conduit outlets.

6. A fluid pick-up pipe according to any preceding claim wherein the internal rib element extends at least 50% of the distance from the gallery inlet to the manifold portion.

7. A fluid pick-up pipe according to any preceding claim comprising a deflector wall adjacent to the gallery oil inlet, the deflector wall defining a boundary of the gallery conduit and comprising a curved portion presenting a concave surface toward the gallery oil inlet, and thereby being arranged to direct fluid entering the gallery conduit toward the manifold portion in a direction parallel to the sump conduit.

8. A fluid pick-up pipe according to any preceding claim wherein a cross-sectional area of the sump inlet is less than a cross-sectional area of the sump fluid conduit.

9. A fluid pick-up pipe according to any preceding claim wherein the sump fluid conduit is longer than the gallery fluid conduit, the sump fluid conduit extending rearwardly away from the manifold portion a greater distance than the gallery fluid conduit.

10. A fluid pick-up pipe according to any preceding claim comprising a first seal and a second seal circumferentially arranged around the fluid pick-up pipe, wherein the gallery inlet is positioned between the first seal and the second seal.

11. A fluid recirculation system comprising:a fluid pump; anda fluid pick-up pipe according to any preceding claim.

12. A vehicle powertrain comprising:an electric drive portion comprising an electric machine operatively coupled to a transmission; anda fluid recirculation system according to claim 11,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 recirculation system comprising a 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 through the gallery to the fluid pick-up pipe bypassing the transmission.

13. A vehicle comprising a powertrain according to claim 12.

14. A method of cooling and / or lubricating an electric drive portion of a powertrain by means of a fluid recirculation system having a fluid pump, and a fluid pick-up pipe comprising:a gallery inlet configured to receive fluid from a fluid gallery of the electric machine;a sump inlet configured to receive fluid from a fluid sump of the transmission;an outlet configured to emit fluid from the fluid pick-up pipe to the fluid pump; anda manifold portion in fluid communication with the outlet;the method comprising:directing fluid received through the gallery inlet to flow through a gallery fluid conduit;directing fluid received through the sump inlet to flow through a sump fluid conduit;directing fluid to flow into the manifold portion from the sump fluid conduit and directing fluid to flow into the manifold portion from the gallery fluid conduit, thereby combining the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit in the manifold portion and emitting the combined flow at the outlet.

15. A method of cooling and / or lubricating an electric drive portion of a powertrain according to claim 14, wherein an angle between respective centrelines of the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit is in the range from zero degrees to 45 degrees where the flow of fluid from the sump fluid conduit and the flow of fluid from the gallery fluid conduit combine in the manifold.17

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