GB2641234A

GB2641234A - Bearing sleeve

Info

Publication number: GB2641234A
Application number: GB2407146.6A
Authority: GB
Inventors: Johnson Jack; Carvajal Chiappara Gerardo
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2024-05-20
Filing date: 2024-05-20
Publication date: 2025-11-26
Also published as: WO2025242627A1; GB202407146D0

Abstract

A bearing mounting sleeve being an annular housing defining a cavity 102 for mounting a bearing, having a passage 116 for supplying lubricant oil into the bearing cavity 102. Sleeve may include a first cylindrical section 102a and a second radially inwardly extending shoulder 102b having a chamfer 103. The lube passage may open into the inner surface of the cavity. Groove 113 (fig 5) extending partially circumferentially on the outer surface 104 may have smaller cross-sectional area than the oil hole 116, acting as a lubricant flow restrictor orifice. The passage 116 may be of two straight sections 116a, 116b in different directions. Also claimed a bearing assembly mounted adjacent the shoulder axially (fig 6) which thermal expansion coefficient may be same as the sleeve. The bearing may be for a rotor shaft of a vehicle propulsion drive unit.

Description

BEARING SLEEVE

TECHNICAL FIELD

The present disclosure relates to a bearing sleeve. Aspects of the invention relate to a bearing sleeve, to a vehicle drive unit comprising said bearing sleeve, and to a vehicle comprising said vehicle drive unit.

BACKGROUND

It is known to provide bearings in mechanical systems for supporting rotary components (such as shafts) to help reduce energy lost due to friction.

However, in many systems, the material from which the bearings are made may be different from that of neighbouring elements. Since different materials tend to exhibit different coefficients of thermal expansion, this can often lead to neighbouring elements exerting a load onto neighbouring bearings during operation due to the differing rates of thermal expansion of the two materials. This can reduce the clearance between the inner and outer bearing races causing them to "pinch" which can significantly reduce the fatigue life of the bearing.

Alternatively, if the clearance between the inner and outer races is too great, this can cause the bearing balls to "skid" which also reduces the fatigue life of the bearing.

To help address this problem, it is known to house bearings within a bearing sleeve to better isolate the bearings from the forces generated due to thermal expansion of neighbouring elements and hence maintain the correct spacing between the inner and outer bearing races.

A further known issue related to bearing is to ensure that the bearings remain adequately lubricated. This often requires the use of additional components, such as a lubricant jet located away from the bearing, which can increase the weight, cost, and complexity of a given system.

It is an aim of the present invention to address this problem.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a bearing sleeve, a bearing assembly, a vehicle drive unit and a vehicle as claimed in the appended claims.

According to an aspect of the present invention there is provided a bearing sleeve comprising: an inlet for receiving lubricant from a lubricant supply; an opening for dispensing the lubricant internally of the sleeve; and a fluid passage arranged to fluidically couple the inlet to the opening.

The bearing sleeve may comprise an at least partially annular body having an inner surface which defines at least a portion of a cavity internally of the sleeve for housing a bearing.

The inlet, fluid passage and opening, when coupled to a lubricant supply, may allow lubricant to pass directly through the bearing sleeve to dispense lubricant onto a bearing received within the bearing sleeve such that the bearing is adequately lubricated. This provides a lubrication means that has a reduced part count relative to known arrangements, such as the provision of an oil jet that is separate from the bearing sleeve. The assembly of the bearing and sleeve may therefore be simplified.

Optionally, the opening may be provided on the inner surface of the bearing sleeve. By providing the opening on the inner surface of the annular body, the bearing sleeve may more accurately dispense lubricant onto the bearing housed therein.

Optionally, the inner surface may comprise a first portion arranged to engage the bearing and a second portion axially adjacent the first portion, the second portion having the opening. By providing the opening in a portion of the inner surface that does not house the bearing, the lubricant may be directed into the bearing in a direction having an axial component, improving lubrication of the bearing.

Optionally, the second portion may extend radially inwardly from the first portion. By providing a second portion extending radially inwards from the first portion, the bearing may be axially restrained and the opening may be maintained at a fixed position relative to the bearing in an axial direction. The bearing sleeve may comprise a shoulder portion protruding in a radial direction into the cavity; and the shoulder portion may extend in a circumferential direction at least partially around the inner surface of the bearing sleeve. The radially protruding shoulder may abut against parts of the bearing housed within the cavity such as an outer race of the bearing, thereby helping to prevent unwanted axial movement of the bearing during use.

Optionally, the second portion may be a chamfered surface. By using a chamfered surface, the opening may be directed at an angle toward the inside of the bearing. The chamfer may be at a 45° angle to the axis of the bearing, allowing improved directing of the lubricant using conventional manufacturing methods. The chamfered surface may be in the shoulder portion and angled towards a centre of the cavity, and the opening for dispensing the lubricant into the cavity may be provided in the chamfered surface.

By providing the opening in the chamfered surface, the opening may be better angled towards the cavity thereby helping to more accurately dispense lubricant onto the bearing housed therein.

The fluid passage may extend at least partially through the shoulder portion. Providing the fluid passage through the thickest region of the bearing sleeve (i.e., the shoulder portion) may help to maintain the structural integrity of the bearing sleeve.

Optionally, the bearing sleeve may comprise a restrictor arranged to restrict the flow of lubricant from the inlet to the opening. The restrictor may act to manage the flow of lubricant onto the bearing, avoiding drag on the bearing due to excess lubricant. While a restrictor may be provided separately from the bearing sleeve, the integration of the restrictor within the bearing sleeve may further reduce the part count of the assembly, further improving ease of assembly.

Optionally, the inlet may comprise a groove extending in a circumferential direction at least partially around an outer surface of the bearing sleeve. By providing a groove extending in a circumferential direction at least partially around an outer surface, the inlet may be coupled to the lubricant supply more easily, i.e., with a lower level of precision being required. Further, if the bearing sleeve rotates during use the connection to the lubricant supply may be maintained.

Optionally, the outer surface may be a radially outer surface. Providing a groove on an outer surface radially outward from the inner surface may allow the flow of lubricant to be restricted before it passes radially through the bearing sleeve towards the bearing.

Optionally, the groove may have a smaller cross-sectional area than the fluid passage, such that the groove is configured to restrict the flow of lubricant passing from the inlet to the opening. The dimensions of the outer surface may be easy controlled and therefore by configuring the groove so as to act as a restrictor, the flow of fluid may be better controlled.

Optionally, the fluid passage may comprise a first straight portion and a second straight portion, wherein the first straight portion intersects the second straight portion, and wherein the first straight portion extends in a different direction from the second straight portion.

Providing a fluid passage with straight, intersecting portions may allow an improved ease of manufacture as the straight portions may be provided by known manufacturing methods, such as drilling. The first straight portion may intersect the second portion at an angle between 10° and 80°. By providing the straight sections intersecting at an angle of between 10° and 80°, the opening and the straight portion leading to the opening may be angled appropriately to direct lubricant onto the bearing.

Optionally, the fluid passage may pass through the at least partially annular body at least partially in a radial direction.

By arranging the fluid passage radially through the at least partially annular body, the arrangement may be made more compact, and the fluid passage may be less susceptible to leakage due to the protection of the surrounding bearing sleeve.

According to another aspect of the invention, there is provided a bearing assembly comprising: an inner bearing race; an outer bearing race; a plurality of rolling elements arranged between the inner and outer bearing races, and the bearing sleeve according to the previous aspect of the invention, wherein the opening of the bearing sleeve is arranged to direct lubricant toward the inner bearing race, the outer bearing race and/or one or more of the rolling elements arranged between the inner and outer bearing races.

The bearing sleeve, when coupled to a lubricant supply, may allow lubricant to pass directly through the bearing sleeve to dispense lubricant onto parts of the bearing received within the bearing sleeve such that the bearing is adequately lubricated. This provides a lubrication means that has a reduced part count relative to known arrangements, such as the provision of an oil jet that is separate from the bearing sleeve. The assembly of the bearing and sleeve may therefore be simplified.

Optionally, the outer bearing race and the bearing sleeve may be formed of materials having substantially the same coefficient of thermal expansion.

Where a bearing race is formed from a material having a different coefficient of thermal expansion to that of the bearing sleeve, thermal expansion and/or contraction of the materials may differ, resulting in compressive forces on the bearing varying. This may lead to skidding of the rolling elements of the bearing or to a higher friction.

By providing an outer bearing race and a bearing sleeve formed of materials having substantially the same coefficient of thermal expansion, such forces can be better avoided, thereby improving the performance of the bearing.

Optionally, the outer bearing race and the bearing sleeve may be formed of the same material.

According to yet another aspect of the invention, there is provided a vehicle drive unit comprising: a rotor shaft; a housing structure; and the bearing assembly according to the previous aspect of the invention, wherein the bearing assembly is arranged between the rotor shaft and the housing structure.

Optionally, the housing structure may be a bulkhead.

Optionally, the housing structure may be formed of a different material to that of the bearing sleeve.

Where a bearing is formed from a material that is different from the material of a surrounding structure, thermal expansion and/or contraction of the materials may differ, resulting in compressive forces on the bearing varying. This may lead to skidding of the rolling elements of the bearing or to a higher friction. The bearing sleeve may resist such forces, thereby improving the performance of the bearing.

Optionally, the vehicle drive unit may further comprise a lubricant supply, the lubricant supply comprising a lubricant supply pipe integrated into the housing structure and in fluidic communication with the inlet of the bearing sleeve.

Optionally, the vehicle drive unit may further comprises an electric machine, the electric machine comprising a stator and a rotor rotatable relative to the stator, the rotor being fixed to the rotor shaft.

According to a further, aspect of the invention, there is provided a vehicle comprising the vehicle drive unit according to the previous aspect of 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 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 a first bearing sleeve according to an embodiment of the invention; Figure 2 shows a cross sectional view of the first bearing sleeve; Figure 3 shows a cross sectional view of a second bearing sleeve according to the invention; Figure 4 shows a cross sectional view of a third bearing sleeve according to the invention; Figure 5 shows a perspective view of a fourth bearing sleeve according to the invention; Figure 6 shows a cross sectional view of a bearing assembly according to the invention; Figure 7 shows a schematic cross sectional view of a first vehicle drive unit according to the invention; Figure 8 shows a schematic cross sectional view of a second vehicle drive unit according to the invention; and Figure 9 shows a vehicle according to the invention.

DETAILED DESCRIPTION

It is known to use a sleeve to house a bearing, particularly in applications where thermal expansion of the bearings occurs at a different rate to the thermal expansion of surrounding components, such as a bulkhead in which the bearing is located. In this case, the sleeve may be designed to resist the stress that would otherwise be exerted directly on the bearing due to differential expansion of the bearing and an adjacent component.

Bearings require lubrication during operation to reduce friction between moving parts of the bearing, improving bearing performance by reducing wear and improving efficiency of the bearings. Reducing friction between moving parts of the bearing may also help to reduce the heat generated by the bearing which may also improve performance of the bearing and adjacent components. It is known to spray lubricant such as oil onto a bearing, in order to lubricate the bearing. Further, where heat builds up in a bearing, the lubricant may act as a cooling fluid, absorbing heat from the bearing and thereby cooling the bearing. However, arranging systems to spray lubricant may be time consuming and reliability of the systems may be sub optimal.

Figure 1 shows a bearing sleeve 100 (also referred to as a sleeve 100) comprising an annular body with a longitudinal sleeve axis Al. The sleeve 100 has an inner surface 102 and an outer surface 104, the outer surface arranged radially outward of the inner surface. The inner surface 102 defines a cavity for housing a bearing. In some cases, the inner surface may define only a portion of a cavity for housing a bearing, such that part of the bearing may be housed outside of the sleeve 100. Although shown as a completely annular body, the sleeve 100 may comprise a partially annular body, for example the sleeve 100 may have a generally C-shaped body forming a portion of a ring. Alternatively, the bearing sleeve may be formed of multiple arcuate segments.

The sleeve 100 comprises an inlet 112 for receiving lubricant from a lubricant supply and an opening 114 for dispensing lubricant into the cavity. The inlet 112 and the opening 114 are fluidically coupled by a fluid passage 116. The opening 114 may be provided on the inner surface 102 of the sleeve 100. The inlet 112 may be provided on the outer surface 104 of the sleeve 100, and the fluid passage 116 may extend radially through the sleeve to connect the inlet 112 and the opening 114.

Figure 2 shows a cross section of the sleeve 100, where the inlet 112 and opening 114 are located at the same circumferential position about the axis Al and the same axial position along the axis Al, such that the fluid passage 116 extends in the radial direction only.

As shown in Figure 2, the sleeve 100 may comprise a restrictor 118 arranged to restrict the flow of lubricant from the inlet 112 to the opening 114. The restrictor 118 may be a separate component within the fluid passage 116 as shown in Figure 2, or an integral feature of the fluid passage 116 such as a step change in diameter of the passage. Providing a restrictor 118 within the sleeve 100 may provide a more compact arrangement compared to using a restrictor arranged outside of the sleeve 100.

It is known to use a restrictor 118 to control the rate of flow of lubricant through a fluid system. The fluid system may for example require an internal pressure to be above a predetermined value (a back pressure requirement) such that fluid may be delivered to all components within the fluid system at the required pressure and/or flow rate. Restrictors may be fitted to individual components to control the rate at which fluid is supplied to and/or output by the component.

As shown in Figure 3, the inner surface 102 may comprise a first cylindrical portion 102a, a second cylindrical portion 102b axially adjacent the first portion and a shoulder portion 106 between the first and second cylindrical portions 102a, b. The shoulder 106 extends radially inwardly from the first cylindrical portion 102a. The shoulder 106 may be perpendicular to the first portion 102a. The bearing, preferably an outer race of the bearing, may abut the shoulder 106 to axially constrain the bearing. Alternatively, the second portion 102b may be axially spaced away from the bearing. The first portion 102a is arranged to engage an outer surface of an outer race of the bearing, and the opening 114 is provided on the second portion 102b.

The fluid passage 116 may comprise a single straight portion as illustrated in Figure 2. Alternatively, the fluid passage 116 may comprise a plurality of straight portions. Figure 3 shows an example of a fluid passage 116 having a first straight portion 116a extending radially inwards from the inlet 112, and a second straight portion 116b extending from the opening 114. The first straight portion 116a intersects the second straight portion 116b such that the two are fluidically connected. By providing a second straight portion 116b extending in a different direction from the first straight portion 116a, the direction in which the lubricant exits the opening 114 may be better controlled and directed to lubricate the bearing. The first straight portion 116a has a first axis A2 and the second straight portion has a second axis A3. The first and second axes A2, A3 may intersect at an angle of between 10° and 80°.

The first straight portion 116a and the second straight portion 116b may be manufactured by any suitable manufacturing method. It may be convenient to drill the first straight section 116a from the outer surface 104 of the sleeve, and to drill the second straight portion 116b from the inner surface 102 of the sleeve. It will be understood that a curved fluid passage may be provided, although this may be more difficult to manufacture than a fluid passage comprising two straight portions, with one straight portion extending from each of the inlet and the opening.

The opening 114 of the fluid passage 116 may extend through the shoulder 106 of the sleeve 100. The shoulder 106 may be a flat surface of the sleeve 100.

The shoulder 106 may be a surface that is perpendicular to the adjacent inner and outer portions 102a, b. This may provide a high normal reaction force for retaining the bearing axially. Generally, the shoulder 106 may have a shape that corresponds to a shape of an adjacent surface of the bearing. This may be a curved shape that interlocks with a corresponding curve of the bearing, or the first portion and the second portion 102a,b may overlap with the shoulder portion 106 forming an "overhang portion" where an angle between the shoulder 106 and the first portion is an acute angle.

It will be appreciated that the fluid passage 116 of any sleeve 100 described herein (such as the sleeve 100 shown in Figure 2) may comprise a plurality of intersecting straight portions. Where the fluid passage 116 comprises a plurality of intersecting straight portions, each straight portion may have a different diameter and/or a different cross-sectional shape. Providing portions having different diameters may restrict fluid flow through the fluid passage 116. As described previously, each fluid passage portion may be drilled separately and arranged to intersect. Alternatively, the fluid passage 116 may be manufactured as an integral feature of the sleeve 100. Intersecting fluid passage portions may intersect at any angle, preferably to direct the flow of fluid towards the inner surface 102 of the sleeve 100. Generally, the fluid passage 116 may pass through the body of the sleeve 100 at least partially in the radial direction as defined by the sleeve axis Al.

Figure 4 shows a further example of a sleeve 100 comprising an inner surface 102 with a first portion 102a and a second portion 102b. In this case, the second portion 102b has a chamfered surface 103 inclined at an oblique angle relative to the first portion 102a. The opening 114 is formed in the chamfered surface 103. The fluid passage second portion 116b may extend perpendicularly from the chamfered surface 103. As such, the angle of the chamfered portion may be selected to control the direction in which fluid is dispensed from the opening 114 and/or to control where the first straight portion 116a of the fluid passage intersects with the second straight portion 116b. Providing a chamfered edge on the inner surface second portion 102b may improve ease of manufacture of the fluid passage 116 as the fluid passage second portion 116b may be drilled normal to the second surface rather than at an angle.

The inlet 112 may comprise a groove 113 as shown in Figure 5. The groove 113 extends in a circumferential direction partially around the outer surface 102 of the sleeve 100. Generally, the groove 113 may extend around at least 20% of the circumference of the sleeve 100, subtending an angle of at least 72°, preferably the groove may extend around at least 25% of the circumference of the sleeve, subtending an angle of at least 90°, further preferably around at least 30% of the circumference of the sleeve, subtending an angle of at least 108°. Alternatively, the groove may have a length of at least 20mm, preferably at least 30mm. Providing a groove 113 may improve ease of assembly of the sleeve 100 and lubricant supply, as the groove provides a larger area for receiving fluid for transfer to the inlet 112, allowing easier alignment with a lubricant supply. The sleeve 100 and lubricant supply may therefore be coupled together with a lower level of precision in the circumferential direction compared to a sleeve not having a groove 113. The groove 113 may also maintain fluid connection between the lubricant supply and the inlet 112 should the sleeve 100 rotate relative to the lubricant supply during operation. Although shown as extending from the inlet 112 in a single circumferential direction only, it will be appreciated that the groove 113 may extend in both circumferential directions. The groove 113 has an axial width measured in a direction parallel to the axis Al of the sleeve. The axial width of the groove 113 may be equal to or greater than the diameter of the inlet 112.

The groove 113 may have a smaller cross-sectional area than the fluid passage 116 as shown in Figure 5. This may act to restrict the flow of lubricant passing from the inlet to the opening by restricting flow of lubricant to the inlet 112. In this way the groove 113 may act as a restrictor. The groove may act as a restrictor as an additional restrictor to the restrictor 118 described previously or as an alternative restrictor. The depth and/or width and hence cross-sectional area of the groove 113 may be closely controlled during manufacture, for example by machining the groove. The cross-sectional area of the groove 113 may be less than 60%, preferably less than 50%, further preferably less than 45% of the cross-sectional area of the fluid passage 116.

This may therefore provide a convenient way to integrate a method of controlling flow of lubricant into the sleeve 100 design.

Figure 6 shows a bearing assembly 200 comprising a bearing 210 housed within the bearing sleeve 100 of Figure 4. The bearing 210 comprises an inner race 212, an outer race 214 and a plurality of rolling elements 216 arranged between the inner and outer races 212, 214. The rolling elements may be substantially spherical in the case of a ball bearing, but other types of bearings such as needle bearings may also be used. The sleeve 100 shown in Figure 6 comprises the shoulder 106 which the outer race 214 abuts to axially constrain the bearing.

The opening 114 of the sleeve 100 is arranged to direct lubricant towards the bearing 210. As described previously, the second portion 102b of the inner surface 102 and/or the fluid passage 116, and optionally the second straight portion 116b of the fluid passage may be angled to direct the flow of lubricant toward an appropriate part of the bearing 210. The lubricant may be directed towards the inner race 212, the outer race 214 and/or one or more of the rolling elements 216.

It may be preferable to provide a bearing 210 with an outer race 214 formed of materials having the same coefficient of thermal expansion as the material which forms the sleeve 100. This may cause the outer race 214 to expand and/or contract at the same rate as the sleeve 100, which may reduce the variation in stresses applied to the bearing 210 by the sleeve due to thermal expansion of the bearing assembly 200. Reducing the range of stress applied to the bearing 210 may improve the lifespan of the bearing and/or may improve the efficiency at which the bearing operates.

The bearing assembly 200 may be part of a vehicle drive unit 300 as shown in Figure 7. The vehicle drive unit 300 may, in some cases, comprise two bearing assemblies 200 spaced apart in an axial direction. The vehicle drive unit 300 comprises a rotor shaft 310, a housing structure 320 and the bearing assembly 200. The bearing assembly 200 is arranged between the rotor shaft 310 and the housing structure 320 to support the rotor shaft. The vehicle drive unit 300 may further comprise an electric machine 340 arranged to generate a torque, or electricity. The electric machine 340 may comprise a stator 342 and a rotor 344. The stator 342 may be fixed to the housing structure 320 and the rotor 344 may be fixed to the rotor shaft 310. The electric machine 340 is configured to generate a torque to rotate the rotor 344 relative to the stator 342 which in turn rotates the rotor shaft 310. Alternatively, electric machine 340 may be operated as a generator, where torque from the shaft 310 rotates the rotor 344 relative to the stator 342 and which generates electricity in the stator.

The vehicle drive unit 300 may comprise a plurality of bearing assemblies 200. Each bearing assembly 200 may be fastened to the housing structure 320 and arranged to support the rotor shaft 310. By way of non-limiting example, the vehicle drive unit 300 may comprise two bearing assemblies 200 and an electric machine 340 comprising a rotor 344 fixed to a rotor shaft 310 as described previously. The electric machine 340 may be arranged between the two bearing assemblies 200 and each of the two bearing assemblies may support the rotor shaft 310.

One or more of the bearing assemblies 200 may be arranged in a bulkhead 325 of the vehicle drive unit. The bulkhead 325 may separate a power source portion of the drive unit, such as a portion housing an electric machine, from a drivetrain portion, such as a portion housing one or more gears 360, 370.

Figure 8 shows a further vehicle drive unit 300 comprising a lubricant supply 330. The lubricant supply 330 may comprise a reservoir separate to the housing structure 320 and outside the vehicle drive unit 300 as shown in Figure 8 or may be formed as an integral part of the housing structure and/or may be inside the vehicle drive unit 300. The sleeve 100 is fluidically connected to the lubricant supply 330 by a lubricant supply pipe 332, optionally where a lubricant supply pipe is integrated into the housing structure 320 as shown in Figure 8.

A further embodiment of the invention provides a vehicle 400 comprising the vehicle drive unit 300 as shown in Figure 9. Where the vehicle 400 comprises a vehicle drive unit 300 with a lubricant supply 330, the lubricant supply may comprise a reservoir for storing lubricant and a pipe system for dispensing lubricant from the reservoir. Optionally a pump may be used to drive lubricant through the pipe system. The lubricant from the reservoir may be used to lubricate the bearing(s) comprised within the vehicle drive unit 300 and optionally any other components within the vehicle 400, for example gears and further bearings outside of the vehicle drive unit 300.

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

CLAIMS1. A bearing sleeve comprising: an at least partially annular body having an inner surface which defines at least a portion of a cavity for housing a bearing; an inlet for receiving lubricant from a lubricant supply; an opening for dispensing the lubricant into the cavity; and a fluid passage arranged to fluidically couple the inlet to the opening.
2. A bearing sleeve according to claim 1, wherein the opening is provided on the inner surface of the bearing sleeve.
3. A bearing sleeve according to claim 2, wherein the inner surface comprises a first portion arranged to engage the bearing and a second portion axially adjacent the first portion, the second portion having the opening.
4. A bearing sleeve according to claim 3, wherein the second portion extends radially inwardly from the first portion.
5. A bearing sleeve according to claim 2, 3 or 4, wherein the second portion has a chamfered surface.
6. A bearing sleeve according to any preceding claim, further comprising a restrictor arranged to restrict the flow of lubricant from the inlet to the opening.
7. A bearing sleeve according to any preceding claim, wherein the inlet comprises a groove extending in a circumferential direction at least partially around an outer surface of the bearing sleeve.
8. A bearing sleeve according to claim 7, wherein the groove has a smaller cross-sectional area than the fluid passage, such that the groove is configured to restrict the flow of lubricant passing from the inlet to the opening.
9. A bearing sleeve according to any preceding claim, wherein the fluid passage comprises a first straight portion and a second straight portion, wherein the first straight portion intersects the second straight portion, and wherein the first straight portion extends in a different direction from the second straight portion.
10. A bearing assembly comprising: an inner bearing race; an outer bearing race; a plurality of rolling elements arranged between the inner and outer bearing races, and the bearing sleeve of any preceding claim, in the cavity of which the outer bearing race is mounted, wherein the opening of the bearing sleeve is arranged to direct lubricant toward the inner bearing race, the outer bearing race and/or one or more of the rolling elements arranged between the inner and outer bearing races.
11. A bearing assembly according to claim 10, wherein the outer bearing race and the bearing sleeve are formed of materials having substantially the same coefficient of thermal expansion.
12. A bearing assembly according to claim 10 or 11, when dependent on claim 4, wherein the outer bearing race is radially located in said first portion of the inner surface and is axially located by a shoulder between the first and second portions of the inner surface.
13. A vehicle drive unit comprising: a rotor shaft; a housing structure; and the bearing assembly of claim 10, 11 or 12, wherein the bearing assembly is mounted in the housing structure and the rotor shaft is supported by the inner bearing race.
14. A vehicle drive unit according to claim 13, further comprising a lubricant supply, the lubricant supply comprising a lubricant supply pipe integrated into the housing structure and in fluidic communication with the inlet of the bearing sleeve.
15. A vehicle comprising the vehicle drive unit according to claim 13 or 14.