Rotor shaft system with increased rigidity

Abstract

A rotor shaft system for a vehicle includes a rotor shaft having a first shaft end opposite a second shaft end. The rotor shaft has a first segment and a second segment defined between the first shaft end and the second shaft end. The rotor shaft system includes a shaft gear connected to the rotor shaft between the first shaft end and the first segment, and a shaft sleeve connected to the first segment to surround a portion of the shaft gear. The rotor shaft system includes a lubrication system extending at least partially through the rotor shaft and the shaft sleeve. The lubrication system is for supplying a fluid to at least a portion of the rotor shaft and the shaft sleeve.

Description

Technical FieldThe technical field relates generally to a drive system for a vehicle, and more particularly to a drive system for a vehicle having a rotor shaft system with increased rigidity.IntroductionGenerally, the propulsion system of a vehicle, e.g., a hybrid or electric vehicle, may include an electric motor. The electric motor provides power to a transmission system, which in turn transfers the power from the propulsion system to one or more vehicle wheels. In certain examples, it is desirable to increase the speed of the electric motor. To increase the speed of the electric motor, the size of a rotor associated with the electric motor may be reduced, resulting in a corresponding reduction in the size of a rotor shaft associated with the electric motor. However, the reduction in the size of the rotor shaft may result in increased flexibility of the rotor shaft. The increased flexibility of the rotor shaft may result in a decreased lateral stiffness of the rotor shaft, which is undesirable.DE 10 2019 207 312 A1 describes a cooling arrangement for a heat-generating rotating component of an electric machine, comprising a rotatably mounted rotor shaft which extends in an axial direction about an axis of rotation, wherein the rotor shaft has an outer side of the rotor shaft and, in the axial direction, a first end side and a second end side on the end side, a rotatably mounted hollow shaft which is mounted coaxially with the rotor shaft and is connected thereto in a rotationally fixed manner, wherein the hollow shaft has an inner side of the hollow shaft facing the rotor shaft and an outer side of the hollow shaft opposite this inner side of the hollow shaft, wherein the inner side of the hollow shaft is arranged at a distance from the outer side of the rotor shaft to form an annular gap, a cooling channel for the flow of cooling lubricant therethrough, which extends from the first end face in the axial direction in a non-continuous manner in the rotor shaft and which is designed open to the first end face for the inflow of the cooling lubricant, a deflecting duct which is arranged in the rotor shaft and extends from the cooling duct into the annular gap for deflecting the cooling lubricant flowing through the cooling duct into the annular gap, an inflow duct which is fluidically connected to the cooling duct for supplying the cooling lubricant to the cooling duct.DE 10 2018 213 609 A1 describes a rotor for an electric machine having a rotor shaft rotatable about a rotor axis and a laminated core arranged in a positive-locking manner on the rotor shaft. The rotor shaft has a shaft outer side on a side facing the laminated core, and the laminated core comprises a laminated core inner side on a side facing the rotor shaft. At least one cavity is formed between the shaft outer side and the laminated core inner side at least in sections. The rotor shaft has a cooling duct with an inlet opening and an outlet opening formed at a distance from the inlet opening, and the outlet opening is arranged on the outer side of the shaft in such a way that a cooling medium entering the cooling duct can be injected directly into the cavity via the outlet opening.DE 11 2017 004 016 T5 describes a motor having a rotor which rotates about a motor axis and a stator which is positioned on the radially outer side of the rotor. The rotor includes a shaft extending along the motor axis, a rotor core surrounding the shaft from the radially outer side, a plate-shaped end plate positioned on an axial end portion of the rotor core, and a lid portion positioned on an axial end portion of the rotor core with the end plate interposed therebetween. The end plate is provided with a plate through hole extending in the axial direction, a first recessed portion extending from the plate through hole to the radially inner side, and a second recessed portion extending from the plate through hole to the radially outer side. The first recessed portion opens on the radially inner side of the end plate. An opening of the first recessed portion facing in the axial direction is covered by the rotor core. An opening of the second recessed portion facing in the axial direction includes a covered portion covered by the lid portion and an open portion not covered by the lid portion.Accordingly, it is an object of the invention to provide a rotor shaft system for an electric motor with increased rigidity, which provides a rotor shaft that enables higher rotational speeds for an electric motor without impairing the lateral rigidity of the rotor shaft. Moreover, other desirable features and characteristics of the present disclosure will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.DESCRIPTION OF THE INVENTIONThe invention is defined by the claims.According to various embodiments, a rotor shaft system for a vehicle is provided. The rotor shaft system includes a rotor shaft having a first shaft end opposite a second shaft end. The rotor shaft has a first segment and a second segment defined between the first shaft end and the second shaft end. The rotor shaft system includes a shaft gear coupled to the rotor shaft between the first shaft end and the first segment, and a shaft sleeve coupled to the first segment to surround a portion of the shaft gear. The rotor shaft system includes a lubrication system that extends at least partially through the rotor shaft and the shaft sleeve. The lubrication system is configured to provide a fluid to at least a portion of the rotor shaft and the shaft sleeve.The rotor shaft includes a first shaft bore extending from the first shaft end through the first segment and at least a portion of the second segment, and the first shaft bore is in fluid communication with the lubrication system. The lubrication system includes a transverse bore that extends through the second segment and is in fluid communication with the first shaft bore. The second segment includes a spline axially defined on an outer periphery of the second segment, and the transverse bore is in fluid communication with the spline. The keyway is configured to couple the rotor shaft to a rotor associated with an electric motor of the vehicle. A lubrication line is defined by a portion of the first segment and the second segment and is in fluid communication with the keyway. The shaft sleeve includes a sleeve lubrication bore in fluid communication with the lubrication conduit. The shaft sleeve encloses a recessed area formed in the first segment proximate the shaft gear. The first segment has a first diameter that is greater than a second diameter of the second segment. The rotor shaft system includes a shaft collar connected to the second segment proximate the second shaft end. The second segment includes a feed groove, and the shaft collar includes at least one opening in fluid communication with the feed groove.According to various embodiments, a vehicle is also provided. The vehicle includes an electric motor having a rotor and a rotor shaft system connected to the electric motor. The rotor shaft system includes a rotor shaft having a first shaft end opposite a second shaft end. The rotor shaft has a first segment and a second segment defined between the first shaft end and the second shaft end. The second segment is coupled to the rotor. The rotor shaft system includes a shaft gear disposed on the rotor shaft between the first shaft end and the first segment. The rotor shaft system includes a shaft sleeve connected to the first segment so as to be disposed between the shaft gear and the rotor, and the shaft sleeve surrounds a part of the shaft gear. The rotor shaft system includes a shaft collar connected to the second segment between the rotor and the second shaft end, and the shaft collar is configured to clamp the rotor and the shaft sleeve to the rotor shaft. The rotor shaft system includes a lubrication system defined by a portion of the rotor shaft and the shaft sleeve. The lubrication system is configured to supply a fluid to at least the portion of the rotor shaft, the shaft sleeve, and the electric motor.The rotor shaft includes a first shaft bore extending from the first shaft end through the first segment and at least a portion of the second segment, and the first shaft bore is in fluid communication with the lubrication system. The lubrication system includes a transverse bore that extends through the second segment and is in fluid communication with the first shaft bore. The second segment includes a spline axially defined on an outer periphery of the second segment, the spline coupled to a key associated with the rotor, and the transverse bore in fluid communication with the spline. A lubrication line is defined by a portion of the first segment and the second segment, and the lubrication line is in fluid communication with the keyway. The shaft sleeve includes a sleeve lubrication bore, and the sleeve lubrication bore is in fluid communication with the lubrication line. The shaft sleeve encloses a recessed area defined in the first segment adjacent the shaft gear. The first segment has a first diameter that is greater than a second diameter of the second segment. The second segment includes a feed groove, and the shaft collar includes at least one opening in fluid communication with the feed groove. The vehicle includes a sensor connected to a second shaft bore at the second shaft end, and the second shaft bore extends axially toward the second segment.Brief Description of the DrawingsThe exemplary embodiments will be described below in conjunction with the following drawings, wherein like reference numerals designate like elements, and wherein: FIG. 1 is a functional block diagram illustrating a vehicle having a rotor shaft system with increased rigidity according to various embodiments; FIG. 2 is a front perspective view of the rotor shaft system coupled to an electric motor connected to a drive system of the vehicle according to various embodiments; FIG. 3 is a cross-sectional view of the rotor shaft system and the electric motor taken along line 3- 3 of FIG. 2 ; FIG. 4 is a rear perspective view of the rotor shaft system coupled to the electric motor in accordance with various embodiments; FIG. 5 is an exploded view of the rotor shaft system and the electric motor according to various embodiments; and FIG. 6 is a cross-sectional view of another example rotor shaft system and the electric motor taken from the perspective of line 3- 3 of FIG. 2 for use with the vehicle of FIG. 1.Detailed DescriptionThe following detailed description is merely exemplary in nature and is not intended to limit the application and use. Moreover, there is no intention to be bound by any explicit or silent theory set forth in the foregoing introduction, description of the invention, or the following detailed description. As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic, and / or processor device, alone or in any combination, including, but not limited to: application specific integrated circuits (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and memory that executes one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.Embodiments of the present disclosure may be described herein in terms of functional and / or logical block components and various processing steps. Such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform the specified functions. For example, an embodiment of the present disclosure may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, that may perform a variety of functions under the control of one or more microprocessors or other controllers. Moreover, those skilled in the art will understand that embodiments of the present disclosure may be used in connection with any number of systems and that the systems described herein are merely exemplary embodiments of the present disclosure.For brevity, conventional techniques associated with signal processing, data transmission, signaling, control, machine learning models, radar, lidar, image analysis, and other functional aspects of the systems (and the individual operating components of the systems) will not be described in detail herein. Moreover, the connection lines depicted in the various figures are intended to represent example functional relationships and / or physical couplings between the various elements. It should be appreciated that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure.As used herein, the term "axial" refers to a direction that is generally parallel to or coincident with an axis of rotation, an axis of symmetry, or the centerline of one or more components. For example, in a cylinder or disk having a centerline and generally circular ends or opposing surfaces, the "axial" direction may refer to the direction extending generally parallel to the centerline between the opposing ends or surfaces. In certain cases, the term "axial" may be used with reference to components that are not cylindrical (or otherwise radially symmetric). For example, for a rectangular housing containing a rotating shaft, the "axial" direction may be considered a direction that is generally parallel to or coincident with the axis of rotation of the shaft. Moreover, the term "radial" as used herein may refer to a direction or relationship of components with respect to a line extending outward from a common centerline, axis, or similar reference point, for example, in a plane of a cylinder or disk that is perpendicular to the centerline or axis. In certain cases, components may be considered "radially" oriented, even though one or both components are not cylindrical (or otherwise radially symmetric). Moreover, the terms "axial" and "radial" (and all terms derived therefrom) may also include directional relationships that are not exactly aligned with (e.g., oblique to) the actual axial and radial dimensions, provided the relationship is predominantly in the respective nominal axial or radial direction. As used herein, the term "about" means within 10% to account for manufacturing tolerances. Moreover, the term "substantially" means a deviation of less than 10% to account for manufacturing tolerances.Referring to FIG. 1, a rotor shaft system with increased stiffness, generally shown as 100, is connected to a vehicle 10 in accordance with various embodiments. In one example, the vehicle 10 is a battery-powered electric vehicle, however, it should be understood that the following disclosure may be applicable to other electric motor-powered devices. As shown in FIG. 1, the vehicle 10 generally includes a chassis 12, a body 14, front wheels 16, and rear wheels 18. the body 14 is disposed on the chassis 12 and substantially encloses the components of the vehicle 10. The vehicle wheels 16- 18 are each rotatably connected to the chassis 12 near a corner of the body 14. In various embodiments, the vehicle 10 is an autonomous vehicle or a semi-autonomous vehicle. As can be appreciated, the rotor shaft system 100 may also be used in other non-autonomous systems and is not limited to the present embodiments. The vehicle 10 is shown as a battery electric passenger car in the illustrated embodiment, but it should be appreciated that any other vehicle including motor bicycles, trucks, sport utility vehicles (SUVs), recreational vehicles (RVs), etc., may also be used.As shown, the vehicle 10 generally includes a propulsion system 20, a transmission system 22, a steering system 24, a braking system 26, a sensor system 28, an actuator system 30, and at least one controller 34. The drive system 20 is coupled to the rotor shaft system 100, which in turn is coupled to the transmission system 22. The transmission system 22 is configured to transmit power received via the rotor shaft system 100 from the propulsion system 20 to vehicle wheels 16 and 18 according to selectable gear ratios. According to various embodiments, the transmission system 22 may include a continuously variable transmission, a stepped variable transmission, or another suitable transmission.The brake system 26 is configured to apply a braking torque to the vehicle wheels 16 and 18. The brake system 26 may include friction brakes, a brake-by-wire system, a regenerative brake system such as an electric machine, and / or other suitable brake systems, in various embodiments.The steering system 24 affects the position of the vehicle wheels 16 and / or 18. Although a steering wheel 24 ais shown for purposes of illustration, the steering system 24 may not include a steering wheel in some embodiments contemplated within the scope of the present disclosure.The sensor system 28 includes one or more sensing devices 40 a- 40 nthat sense observable conditions of the exterior environment and / or the interior environment of the vehicle 10. In various embodiments, the sensor devices 40 a- 40 ninclude radars (e.g., long range, medium range, and short range), lidars, global positioning systems, optical cameras (e.g., front-facing, 360-degree, rear-facing, side-facing, stereo cameras, etc.), thermal cameras (e.g., infrared cameras), ultrasonic sensors, odometry sensors (e.g., encoders), and / or other sensors that may be used in conjunction with systems and methods according to the present subject matter, among others. In one example, the sensor devices 40 a- 40 nmay include a shaft speed sensor 40 acoupled to the rotor shaft system 100 and configured to generate sensor signals based on a speed of a rotor shaft 102 connected to the rotor shaft system 100. The sensor system 28 is connected to the control device 34 via a communication medium.The actuator system 30 includes one or more actuator devices 42 a- 42 nthat control one or more vehicle functions, such as, but not limited to, the propulsion system 20, the transmission system 22, the steering system 24, and the brake system 26. In various embodiments, the vehicle 10 may also include interior and / or exterior vehicle features not shown in FIG. 1, such as various doors, a trunk, and cabin features such as air, music, lighting, touch screen display components, an active safety seat or a haptic seat, and the like.The controller 34 includes at least one processor 44 and a computer readable storage device or medium 46. the processor 44 may be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC) (e.g., a custom ASIC that implements a neural network), a field programmable gate array (FPGA), an auxiliary processor among multiple processors connected to the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), any combination thereof, or generally any device for executing instructions. The computer readable storage device or media 46 may include volatile and non-volatile memory, such as read only memory (ROM), random access memory (RAM), and keep alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables while the processor 44 is off. The computer readable storage device(s) 46 may / may be implemented using any number of known storage devices, such as programmable read only memory (PROM), electrically EPROM (electrically PROM), EEPROM (electrically erasable PROM), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represent executable instructions, used by the controller 34 in controlling the vehicle 10.Referring to FIG. 2, the drive system 20 and the rotor shaft system 100 are illustrated in more detail. As mentioned above, the propulsion system 20 in this example is an electric motor 50, which may have any suitable configuration for use with the vehicle 10. Referring briefly to FIG. 3, the electric motor 50 includes a rotor 52 and a stator 54. the stator 54 surrounds the rotor 52 and includes two or more conductors that generate a magnetic field to rotate the rotor 52.The rotor 52 includes one or more magnets or conductors that also generate a magnetic field. The rotor shaft system 100 is coupled to the rotor 52 and rotates with the rotor 52, The rotor shaft system 100 may be rotatably supported by one or more bearings (not shown). The electric motor 50 may be included between a pair of motor end rings 60, and the output shaft 56 may extend outward from each of the motor end rings 60.In this example, each of the motor end rings 60 is annular, and each of the motor end rings 60 is substantially mirror-symmetrical with respect to an axis perpendicular to a longitudinal axis L of the rotor shaft system 100. Each of the motor end rings 60 defines a central bore 62 and includes a recessed region 64 defined around the central bore 62. The central bore 62 is sized to receive a portion of the rotor shaft system 100 therethrough. The recessed portion 64 extends radially around the central bore 62. the recessed portion 64 forms a contact surface 64 afor coupling the rotor shaft system 100 to the drive system 20.In one example, the rotor shaft system 100 includes the rotor shaft 102, a shaft sleeve 104, a shaft collar 106 (FIG. 4 ), and a lubrication system 108. The rotor shaft 102 is made of a metal or metal alloy and is cast, forged, extruded, additively manufactured, etc. The rotor shaft 102 is substantially cylindrical and extends along the longitudinal axis L. The longitudinal axis L is also a rotational axis of the rotor shaft 102. Rotor shaft 102 includes a first shaft end 110 opposite a second shaft end 112, a shaft gear 114, a first segment or sleeve segment 116, a second segment or rotor segment 118, and a third segment or clutch segment 120. The rotor shaft 102 also defines a first shaft bore 122 and a second shaft bore 124. Referring to FIG. 3, the first shaft end 110 defines a first counterbore 130 that communicates with the first shaft bore 122. The first shaft end 110 also includes a chamfer 132 that extends axially from the first shaft end 110. The first shaft end 110 may be coupled to a bearing, e.g., a ball bearing (not shown), that rotatably supports the rotor shaft 102. The second shaft end 112 defines a second counterbore 134 that communicates with the second shaft bore 124.The shaft gear 114 is defined on the rotor shaft 102 by machining with a lathe, for example. The shaft gear 114 is a pinion gear having a plurality of teeth 136. In this example, the shaft gear 114 is a helical pinion having a plurality of helical teeth. It should be appreciated that the shaft gear 114 on the rotor shaft 102 may be shaped as desired to mate with the transmission system 22. For example, the shaft gear 114 may be formed as a spur gear having a plurality of spur gear teeth, a bevel gear having a plurality of bevel gear teeth, etc. Generally, the shaft gear 114 is coupled to or engages a mating gear M of the transmission system 22 to transfer torque from the drive system 20 to the transmission system 22 (FIG. 3 ). The shaft gear 114 may include any number of gear teeth 136 to couple to the transmission system 22 and drive the transmission system 22, such that the number of gear teeth 136 illustrated herein is merely an example. The shaft gear 114 is disposed on the rotor shaft 102 between the first shaft end 110 and the sleeve segment 116. In one example, the shaft gear 114 has a gear diameter GD, and the gear diameter GD is about 41 millimeters (mm) to about 42 millimeters (mm).The sleeve segment 116 is defined on the rotor shaft 102 immediately adjacent the shaft gear 114. The sleeve segment 116 is defined between the shaft gear 114 and the rotor segment 118. Generally, the shaft sleeve 104 is connected to the rotor shaft 102 so as to be positioned over and connected to the sleeve segment 116. The sleeve segment 116 includes a recessed portion 138, a lubrication groove 142, and a portion of a lubrication conduit 144. The recessed portion 138 is located near or adjacent to the shaft gear 114. The recessed portion 138 allows contaminants, such as metal chips, etc., generated during manufacture of the gear shaft 114 to be removed from the rotor shaft 102. In other words, the recessed portion 138 serves as a cleaning portion. A remainder of the sleeve segment 116 has a first diameter sized and shaped to connect the shaft sleeve 104 to the rotor shaft 102. In one example, the first diameter D 1 is about 38.5 millimeters (mm) to about 40.5 millimeters (mm). The remainder of the sleeve segment 116 extends axially a distance that allows alignment between the lubrication groove 142 and a sleeve lubrication bore 146. The lubrication groove 142 is connected to and in fluid communication with the sleeve lubrication bore 146 and the lubrication conduit 144. The lubrication groove 142 is defined along an axis substantially perpendicular to the longitudinal axis L or is defined radially to the rotor shaft 102. As will be discussed, the lubrication groove 142 directs a fluid F, such as a lubrication fluid and / or a cooling fluid, e.g., oil, to the sleeve lubrication bore 146 of the shaft sleeve 104. As will be discussed, the lubrication line 144 extends along the rotor shaft 102 from the lubrication groove 142 of the sleeve segment 116 to near the second shaft end 112. The lubrication conduit 144 is coupled to or in fluid communication with the lubrication groove 142 to direct or supply the fluid F into the lubrication groove 142.The rotor segment 118 is defined to extend from the sleeve segment 116 to the clutch segment 120. The rotor segment 118 has a second diameter D2 that is different from and less than the first diameter D1 of the sleeve segment 116. A shoulder 147 is defined between the step or change in diameter of rotor shaft 102 from sleeve segment 116 to rotor segment 118. In one example, the second diameter D 2 is about 36 millimeters (mm) to about 38 millimeters (mm). The rotor segment 118 is coupled to the rotor 52 of the electric motor 50. In this example, the rotor segment 118 includes a keyway 148 and a transverse bore 150. The key slot 148 extends axially along an outer surface or periphery of the rotor segment 118 and cooperates with a key 152 formed on the rotor 52. The cooperation between the spline 148 and the key 152 connects the rotor shaft 102 to the rotor 52 to enable torque transfer between the rotor 52 and the rotor shaft 102. Key 152 is shown in key slot 148 in FIG. 3. Thus, the rotor segment 118 is generally coupled to the rotor 52 so as to be driven by the rotor 52. The shaft sleeve 104 and the shaft collar 106 may also help connect the rotor shaft 102 to the rotor 52 along the rotor segment 118. The transverse bore 150 is defined to be substantially equidistant from the pair of motor end rings 60. The transverse bore 150 is substantially cylindrical and extends along an axis which runs substantially perpendicular to the longitudinal axis L. The cross bore 150 is in fluid communication with or fluidly coupled to the first shaft bore 122 to receive the fluid F, and the cross bore 150 is in fluid communication with or fluidly coupled to the lubrication line 144 to direct the fluid F into the lubrication line 144. The transverse bore 150 is also in fluid communication with the keyway 148 to direct the fluid F into the keyway 148.In one example, the rotor segment 118 also includes a feed groove 154. The feed groove 154 is defined around an outer periphery of the rotor segment 118 in the vicinity of the clutch segment 120. The supply groove 154 is in fluid communication with or fluidly coupled to the keyway 148 to receive the fluid F from the keyway 148. The supply groove 154 supplies the fluid F to the motor end ring 60 near the second shaft end 112 and to the shaft collar 106.The clutch segment 120 is defined between the rotor segment 118 and the second shaft end 112. In one example, the clutch segment 120 has a third diameter that is different from and less than the second diameter D 2 of the rotor segment 118. The clutch segment 120 is sized to receive a bearing, such as a ball bearing. The clutch segment 120 includes a clutch groove 156 in this example. The coupling groove 156 is sized and shaped to aid in coupling the bearing to the rotor shaft 102 to support the rotor shaft 102 for rotation. The clutch groove 156 is defined substantially equidistant between the rotor segment 118 and the second shaft end 112.The first shaft bore 122 is defined by the first shaft end 110 and extends from the first shaft end 110 through the sleeve segment 116 and a portion of the rotor segment 118. The first shaft bore 122 extends generally through the rotor segment 118 such that an inner end 122 aof the first shaft bore 122 is substantially coplanar with the motor end ring 60 that is proximate the second shaft end 112. The first shaft bore 122 is separate and discrete from the second shaft bore 124. The first shaft bore 122 is fluidly coupled or in fluid communication with a source 160 of the fluid F and supplies the first shaft bore 122 with the fluid F. In one example, the first shaft bore 122 includes a ledge 122 bdefined downstream of the cross bore 150. The ledge 122 bis an increase or decrease in the inner diameter of the first shaft bore 122 that assists in the movement of the fluid F through the first shaft bore 122.The second shaft bore 124 is defined through the second shaft end 112 and extends from the second shaft end 112 to an inner end 124 adefined within the clutch segment 120 adjacent the rotor segment 118. The second shaft bore 124 defines a plurality of internal threads 158. The internal threads 158 couple to or matingly engage a mechanical fastener, such as a clamping bolt, that can be used to couple the shaft speed sensor 40 aof the sensor system 28 to the rotor shaft 102.The shaft sleeve 104 surrounds the sleeve segment 116 of the rotor shaft 102. The shaft sleeve 104 is made of a metal or metal alloy and is cast, forged, additively manufactured, etc. The shaft sleeve 104 is substantially cylindrical and has a first sleeve end 170 that is opposite a second sleeve end 172. The shaft sleeve 104 also defines the sleeve lubrication bore 146 and a central shaft bore 176. The central shaft bore 176 extends axially from the first sleeve end 170 to the second sleeve end 172, and is sized to enable the shaft sleeve 104 to be connected to the sleeve segment 116. In one example, the shaft sleeve 104 is connected to the sleeve segment 116 by an interference fit or shrink fit. The first sleeve end 170 and the second sleeve end 172 each have a diameter different from and less than a sleeve diameter of a body 178 of the shaft sleeve 104 defined between the first sleeve end 170 and the second sleeve end 172. Generally, the sleeve diameter D is sized to improve lateral stiffness of the rotor shaft 102 and is greater than the gear diameter GD associated with the shaft gear 114. In one example, the sleeve diameter D is equal to or less than the motor diameter MD associated with the electric motor 50. The lateral stiffness of the rotor shaft 102 is a resistance to the deflection or bending of the rotor shaft 102 along the longitudinal axis L. By improving the lateral stiffness of the rotor shaft 102, the shaft sleeve 104 helps to maintain the shaft gear 114 in a substantially parallel relationship to the mating gear M of the transmission system 22, which ensures efficient torque transmission from the rotor shaft 102 to the transmission system 22. In other words, the improved lateral stiffness maintains a central axis A 1 defined by the shaft gear 114 substantially coaxial with the longitudinal axis L, thereby ensuring that the central axis A 1 of the shaft gear 114 is substantially parallel to a central axis A 2 of the counter gear M of the transmission system 22. In one example, the improved lateral stiffness of the rotor shaft 102 reduces the misalignment of the shaft gear 114 and the mating gear M or the misalignment line of action (MLOA) by a factor of 2 to 3.The first sleeve end 170 is connected to the rotor shaft 102 so as to be around and over a portion of the spline 136 of the shaft gear 114. Thus, in this example, the shaft sleeve 104 overlaps, surrounds, or encloses the recessed region 138 of the sleeve segment 116. The first sleeve end 170 is coupled to the rotor shaft 102 around the spline 136, such that it does not interfere with the coupling of the spline 136 to the transmission system 22. The second sleeve end 172 is connected to and in contact with the motor end ring 60 that is proximate the sleeve segment 116. The second sleeve end 172 also overlaps or surrounds the shoulder 147 defined by the difference in diameter between the sleeve segment 116 and the rotor segment 118. Generally, the shaft sleeve 104 is held by a press fit or shrink fit on the rotor sleeve segment and is prevented from axial movement by the shaft gear 114 and the adjacent motor end ring 60.The sleeve lubrication bore 146 is a transverse bore that extends through the body 178 of the shaft sleeve 104. The sleeve lubrication bore 146 is fluidly coupled to or in fluid communication with the lubrication groove 142. The sleeve lubrication bore 146 receives the fluid F from the lubrication groove 142 and directs the fluid F radially outward where the fluid F may flow onto an outer surface of the shaft sleeve 140 and onto the adjacent motor end ring 60.The shaft collar 106 helps to retain the electric motor 50 on the rotor shaft 102. In one example, the shaft collar 106 is substantially L-shaped in cross-section. The shaft collar 106 is made of a metal or metal alloy and is cast, stamped, additively manufactured, etc. The shaft collar 106 includes a first collar end 190 that is opposite a second collar end 192 and defines a central collar bore 194 that extends from the first collar end 190 to the second collar end 192. The first collar end 190 includes a flange 196 extending radially outward from the first collar end 190. Flange 196 includes a coupling surface 196 athat is connected to motor end ring 60 proximate second shaft end 112. In an example related to FIG. 4, the shaft collar 106 is joined to the motor end ring 60 by swaging. The flange 196 defines a plurality of recesses 198 at an intersection between the flange 196 and a collar body 202 of the shaft collar 106. The collar body 202 is defined between the first collar end 190 and the second collar end 192. The recesses 198 engage a groove defined on the motor end ring 60 proximate the second shaft end 112 to assist in coupling the shaft collar 106 to the electric motor 50. It should be appreciated that other techniques may be used to connect the shaft collar 106 to the rotor shaft 102.The second collar end 192 is adjacent the coupling segment 120 when the shaft collar 106 is coupled to the rotor shaft 102. The central collar bore 194 is sized to receive the rotor shaft 102 and is coupled to the rotor shaft 102 to rotate with the rotor shaft 102. The shaft collar 106 also defines a plurality of apertures 200. The openings 200 are defined through the collar body 202 to be spaced apart from each other around a circumference of the collar body 202. The apertures 200 are fluidly coupled or in fluid communication with the supply groove 154 to receive the fluid F from the keyway 148 (FIG. 3 ).Referring to FIG. 3, the lubrication system 108 is in fluid communication with or connected to the source 160 of the fluid F via one or more conduits, hydraulic clutches, etc. The source 160 may include a reservoir containing the fluid F connected to the vehicle 10 (FIG. 1 ), such as an oil reservoir, which may contain a pump or the like, to provide the fluid F to the rotor shaft 102. In one example, the lubrication system 108 includes the first shaft bore 122, the transverse bore 150 defined in the rotor segment 118, the lubrication line 144 defined in the rotor segment 118 and the sleeve segment 116, the lubrication groove 142 defined in the sleeve segment 116, the sleeve lubrication bore 146 defined in the shaft sleeve 104, the feed groove 154 defined in the rotor segment 118, and the apertures 200 of the shaft collar 106.Generally, the fluid F is supplied from the source 160 to the first shaft bore 122. From the first shaft bore 122, the fluid F flows to the transverse bore 150. From the transverse bore 150, the fluid F flows through the keyway 148 to the supply groove 154. From the supply groove 154, the fluid F flows through the openings 200 of the collar to lubricate the bearing connected to the clutch segment 120.From the transverse bore 150, the fluid F also flows along the keyway 148 and / or the lubrication line 144 into the portion of the lubrication line 144 defined in the sleeve segment 116. The fluid F flows from the lubrication line 144 into the lubrication groove 142 and from the lubrication groove 142 into the sleeve lubrication bore 146. From the sleeve lubrication bore 146, the fluid F flows over the outer surface of the body 178 and onto the motor end ring 60 proximate the shaft sleeve 104. By providing the rotor shaft system 100 with the lubrication system 108, the rotor shaft 102 and the electric motor 50 may be lubricated and / or cooled without requiring additional components.It should be noted that although the rotor shaft 102 is described herein as including the shaft gear 114 with the recessed portion 138, the rotor shaft 102 may be configured differently to improve the lateral thickness of the rotor shaft 102. In one example, referring to FIG. 6, a rotor shaft system 300 is shown that may be coupled to the rotor 52 and rotates with the rotor 52. Because the rotor shaft system 300 includes components that are the same or similar as the components of the rotor shaft system 100 discussed with respect to FIGS. 1-5, the same reference numerals are used to designate the same or similar components. In one example, the rotor shaft system 300 includes a rotor shaft 302, the shaft sleeve 104, the shaft collar 106, and the lubrication system 108. The rotor shaft 302 is made of a metal or metal alloy and is cast, forged, extruded, additively manufactured, etc. The rotor shaft 302 is substantially cylindrical and extends along the longitudinal axis L. The longitudinal axis L is also a rotational axis of the rotor shaft 302. Rotor shaft 302 includes first shaft end 110 opposite second shaft end 112, a shaft gear 314, a first segment or sleeve segment 316, second segment or rotor segment 118, and third segment or clutch segment 120. The rotor shaft 302 also defines the first shaft bore 122 and the second shaft bore 124. The first shaft end 110 defines the first counterbore 130 that is in communication with the first shaft bore 122. The first shaft end 110 also includes the chamfer 132. The first shaft end 110 may be coupled to a bearing, e.g., a ball bearing (not shown), that rotatably supports the rotor shaft 302. The second shaft end 112 defines the second counterbore 134 that is in communication with the second shaft bore 124.The shaft gear 314 is defined on the rotor shaft 302 by machining with a lathe, for example. The shaft gear 314 is a pinion having a plurality of teeth 336. In this example, the shaft gear 314 is a helical pinion having a plurality of helical teeth. It should be appreciated that the shaft gear 314 on the rotor shaft 302 may be shaped to mate with the transmission system 22 (FIG. 1 ). For example, the shaft gear 314 may be formed as a spur gear having a plurality of spur gear teeth, a bevel gear having a plurality of bevel gear teeth, etc. Generally, the shaft gear 314 is coupled to or engages the mating gear M of the transmission system 22 to transfer torque from the drive system 20 to the transmission system 22 (FIG. 3 ). The shaft gear 314 may include any number of gear teeth 336 to couple to the transmission system 22 and drive the transmission system 22, and thus the number of gear teeth 336 illustrated herein is just one example. The shaft gear 314 is disposed on the rotor shaft 302 between the first shaft end 110 and the sleeve segment 316. In one example, the shaft gear 314 has a gear diameter GD, and the gear diameter GD is about 41 millimeters (mm) to about 42 millimeters (mm).The sleeve segment 316 is defined on the rotor shaft 302 immediately adjacent the shaft gear 314. The sleeve segment 316 is defined between the shaft gear 314 and the rotor segment 118. Generally, the shaft sleeve 104 is connected to the rotor shaft 302 so as to be positioned over and connected to the sleeve segment 316. The sleeve segment 316 includes a pivot-out portion 338, the lubrication groove 142, and the portion of a lubrication line 144. The pivot portion 338 is defined during the shaping of the shaft gear 314. The pivot portion 338 generally includes a shorter depth spline (336) formed on the lathe during the forming of the gear shaft 314. A remainder of the sleeve segment 316 has the first diameter D 1 sized and shaped to connect the shaft sleeve 104 to the rotor shaft 302. The remainder of the sleeve segment 116 extends axially a distance that allows alignment between the lubrication groove 142 and the sleeve lubrication bore 146. The lubrication groove 142 is connected to and in fluid communication with the sleeve lubrication bore 146 and the lubrication conduit 144. The lubrication conduit 144 is coupled to or in fluid communication with the lubrication groove 142 to direct or supply the fluid F into the lubrication groove 142.The rotor segment 118 is defined to extend from the sleeve segment 316 to the clutch segment 120. The rotor segment 118 has a second diameter D2 that is different from and less than the first diameter D1 of the sleeve segment 116. Shoulder 147 is defined between the step or change in diameter of rotor shaft 302 from sleeve segment 316 to rotor segment 118. The rotor segment 118 is coupled to the rotor 52 of the electric motor 50. The rotor segment 118 includes the keyway 148 and the cross bore 150. Key 152 is shown in key slot 148 in FIG. 6. The rotor segment 118 is coupled to the rotor 52 so as to be driven by the rotor 52. The shaft sleeve 104 and the shaft collar 106 may also help couple the rotor shaft 302 to the rotor 52 along the rotor segment 118. The cross bore 150 is in fluid communication with or fluidly coupled to the first shaft bore 122 to receive the fluid F, and the cross bore 150 is in fluid communication with or fluidly coupled to the lubrication line 144 to direct the fluid F into the lubrication line 144. The transverse bore 150 is also in fluid communication with the keyway 148 to direct the fluid F into the keyway 148. In one example, the rotor segment 118 also includes the feed groove 154. The supply groove 154 is in fluid communication with or fluidly coupled to the keyway 148 to receive the fluid F from the keyway 148. The supply groove 154 supplies the fluid F to the motor end ring 60 near the second shaft end 112 and to the shaft collar 106.The clutch segment 120 is defined between the rotor segment 118 and the second shaft end 112. The clutch segment 120 includes the clutch groove 156 sized and shaped to assist in coupling the bearing to the rotor shaft 302 to support the rotor shaft 302 for rotation.The first shaft bore 122 is defined by the first shaft end 110 and extends from the first shaft end 110 through the sleeve segment 316 and a portion of the rotor segment 118. The first shaft bore 122 is fluidly coupled or in fluid communication with the source 160 of the fluid F and supplies the first shaft bore 122 with the fluid F. In one example, the first shaft bore 122 includes the step or ledge 122 bdefined downstream of the cross bore 150.The second shaft bore 124 is defined by the second shaft end 112 and extends from the second shaft end 112 to the inner end 124 a. The second shaft bore 124 defines internal threads 158 that may be used to couple the shaft speed sensor 40 aof the sensor system 28 to the rotor shaft 302.The shaft sleeve 104 surrounds the sleeve segment 316 of the rotor shaft 302. The central shaft bore 176 extends axially from the first sleeve end 170 to the second sleeve end 172, and is sized to enable the shaft sleeve 104 to be connected to the sleeve segment 316. In one example, the shaft sleeve 104 is connected to the sleeve segment 316 by an interference fit or shrink fit. The first sleeve end 170 and the second sleeve end 172 each have a diameter different from and less than the sleeve diameter D of a body 178 of the shaft sleeve 104 defined between the first sleeve end 170 and the second sleeve end 172. The sleeve diameter D is sized to improve lateral stiffness of the rotor shaft 302 and is greater than the gear diameter GD associated with the shaft gear 114. In one example, the sleeve diameter D is equal to or less than the motor diameter MD associated with the electric motor 50. By improving the lateral stiffness of the rotor shaft 302, the shaft sleeve 104 helps maintain the shaft gear 314 in a substantially parallel relationship to the mating gear M of the transmission system 22, which ensures efficient torque transfer from the rotor shaft 302 to the transmission system 22.The first sleeve end 170 is connected to the rotor shaft 302 to wrap around and over a portion of the spline 336 of the shaft gear 314. Thus, in this example, the shaft sleeve 104 overlaps, surrounds or encloses the pivot-out region 338 of the sleeve segment 316. The first sleeve end 170 is coupled to the rotor shaft 302 around the spline 336 so as not to interfere with the coupling of the spline 336 to the transmission system 22 and to assist in clamping the electric motor 50 to the rotor shaft 302. The second sleeve end 172 is coupled to and in contact with the motor end ring 60 proximate the sleeve segment 316. The second sleeve end 172 also overlaps or surrounds the shoulder 147 defined by the difference in diameter between the sleeve segment 316 and the rotor segment 118. Generally, the shaft sleeve 104 is held by a press fit or shrink fit on the rotor sleeve segment and is prevented from axial movement by the shaft gear 314 and the adjacent motor end ring 60. The sleeve lubrication bore 146 is coupled to or in fluid communication with the lubrication groove 142.The shaft collar 106 helps to retain the electric motor 50 on the rotor shaft 302. The shaft collar 106 includes the first collar end 190 that is opposite the second collar end 192 and defines the central collar bore 194. The first collar end 190 includes the flange 196 having the coupling surface 196 athat is coupled to the motor end ring 60 proximate the second shaft end 112. The shaft collar 106 is joined to the motor end ring 60 by forging. The flange 196 defines a plurality of recesses 198 that engage the groove defined on the motor end ring 60 proximate the second shaft end 112 to assist in coupling the shaft collar 106 to the electric motor 50. It should be appreciated that other techniques may be used to connect the shaft collar 106 to the rotor shaft 302.The second collar end 192 is adjacent the coupling segment 120 when the shaft collar 106 is coupled to the rotor shaft 302. The central collar bore 194 is sized to receive the rotor shaft 302 and is coupled to the rotor shaft 302 to rotate with the rotor shaft 302. The shaft collar 106 also defines the plurality of apertures 200 fluidly coupled to or in fluid communication with the supply groove 154 to receive the fluid F from the keyway 148.The lubrication system 108 is in fluid communication with or connected to the source 160 of the fluid F via one or more conduits, hydraulic clutches, etc. The lubrication system 108 includes the first shaft bore 122, the transverse bore 150 defined in the rotor segment 118, the lubrication line 144 defined in the rotor segment 118 and in the sleeve segment 316, the lubrication groove 142 defined in the sleeve segment 316, the sleeve lubrication bore 146 defined in the shaft sleeve 104, the feed groove 154 defined in the rotor segment 118, and the apertures 200 of the shaft collar 106.Generally, the fluid F is supplied from the source 160 to the first shaft bore 122. From the first shaft bore 122, the fluid F flows to the transverse bore 150. From the transverse bore 150, the fluid F flows through the keyway 148 to the supply groove 154. From the supply groove 154, the fluid F flows through the openings 200 of the collar to lubricate the bearing connected to the clutch segment 120.From the transverse bore 150, the fluid F also flows along the keyway 148 and / or the lubrication line 144 into the portion of the lubrication line 144 defined in the sleeve segment 316. The fluid F flows from the lubrication line 144 into the lubrication groove 142 and from the lubrication groove 142 into the sleeve lubrication bore 146. From the sleeve lubrication bore 146, the fluid F flows over the outer surface of the body 178 and onto the motor end ring 60 proximate the shaft sleeve 104. By providing the rotor shaft system 300 with the lubrication system 108, the rotor shaft 302 and the electric motor 50 may be lubricated and / or cooled without requiring additional components.In an example related to FIGS. 3 and 6, to assemble the rotor shaft system 100, 300 with the electric motor 50 having the rotor shaft 102, 302 formed therein, the first shaft hole 122 and the second shaft hole 124 may be drilled or machined into the rotor shaft 102, 302. The cross bore 150 may be drilled through the rotor segment 118 and the feed groove 154 may be machined through the rotor segment 118. In the example of rotor shaft 102, recessed region 138 is defined in sleeve segment 116. The lubrication groove 142 and the lubrication passage 144 are formed in the rotor shaft 102, 302 by drilling, machining, etc. The spline 148 is machined to mate with the key 152 of the rotor 52. In the example of rotor shaft 102, shaft gear 114 is formed near first shaft end 110 and any debris is removed from recessed area 138. In the example of rotor shaft 302, shaft gear 314 is formed proximate first shaft end 110 and clearing region 338 is defined in sleeve segment 316 during formation of shaft gear 314.When the shaft sleeve 104 is formed, the sleeve lubrication bore 146 is defined by the body 178 of the shaft sleeve 104. The shaft sleeve 104 is pressed or shrunk around the sleeve segment 116, 316. After the stator 54 is connected to the rotor 52 and the motor end rings 60 are connected to the stator 54 and the rotor 52, the rotor 52 is slid onto the key slot 148 of the rotor segment 118 such that the key 152 is received in the key slot 148. The recesses 198 of the shaft collar 106 are aligned with the grooves of the motor end ring 60 proximate the second shaft end 112, and the shaft collar 106 is coupled to the rotor shaft 102, 302 to secure the rotor 52 and the shaft sleeve 104 to the rotor shaft 102, 302. By coupling the shaft sleeve 104 via a portion of the spline 136, 336, coupling the rotor 52 to the rotor shaft 102, 302 such that one of the motor end rings 60 engages the shaft sleeve 104, and clamping the shaft collar 106 to the other of the motor end rings 60 with the shaft collar 106, a clamping path for mounting the electric motor 50 to the rotor shaft 102, 302 extends from the shaft collar 106, through the rotor 52, through the shaft sleeve 104 to the shaft gear 114, 314. Thus, the shaft sleeve 104 is part of the clamping path for coupling the electric motor 50 to the rotor shaft 102, 302.When the electric motor 50 is coupled to the rotor shaft 102, 302, the rotor shaft system 100, 300 and the electric motor 50 may be installed in the vehicle 10. The shaft gear 114, 314 may be coupled to the mating gear of the transmission system 22 to transfer torque from the electric motor 50 to the transmission system 22. The source 160 of the fluid F may be connected to the rotor shaft 102 via conduits, ports, etc. to provide the fluid F to the lubrication system 108.While the propulsion system 20 powers the transmission system 22 to propel the vehicle wheels 16 and / or 18 of the vehicle 10, the rotor 52 rotates the rotor shaft 102, 302. Rotation of the rotor shaft 102, 302 drives the transmission system 22 via the mating gear M coupled to the transmission system 22, which is coupled to the shaft gear 114, 314. The source 160 provides the fluid F to the lubrication system 108 that cools the rotor shaft 102, 302, the shaft sleeve 104, the motor end rings 60, the shaft collar 106, and the bearing coupled to the rotor shaft 102, 302 on the clutch segment 120. The shaft sleeve 104 increases the lateral stiffness of the rotor shaft 102, 302, which reduces the flexibility of the rotor shaft 102, 302 and ensures alignment between the shaft gear 114, 314 and the mating gear M of the transmission system 22. In this regard, the first diameter and the second diameter of the rotor shaft 102, 302 are relatively small, and together with the first shaft bore 122 and the second shaft bore 124, the rotor shaft 102, 302 has a relatively light weight. By providing the rotor shaft 102, 302 with reduced diameters D 1, D 2 and weight, the rotor 52 may drive the rotor shaft 102, 302 at a higher speed and thus in turn drive the transmission system 22 at a higher speed. The reduced diameter and light weight of the rotor shaft 102, 302 may increase the flexibility of the rotor shaft 102, 302, but the shaft sleeve 104 increases the lateral stiffness of the rotor shaft 102, 302 without compromising the speed at which the rotor shaft 102, 302 may be driven. This ensures that the shaft gear 114, 314 remains in a substantially parallel relationship to the counter gear M of the transmission system 22 during operation, and the misalignment of the line of action between the shaft gear 114 and the counter gear M is reduced. The shaft sleeve 104 also reduces a noise and vibration response of the rotor shaft 102, 302 by increasing the stiffness of the rotor shaft 102, 302, which reduces the sound transmitted by operation of the rotor shaft 102, 302. The substantial uniformity of the diameters D 1, D 2 of the rotor shaft 102, 302 also reduces the complexity of manufacture, and the substantially symmetrical shape of the shaft sleeve 104 reduces the complexity of assembly. Moreover, because the shaft sleeve 104 is coupled to and surrounds a portion of the spline 136, 336, it acts as a portion of the shaft gear 114, 314 and is prevented from movement relative to the shaft gear 114, 314.

Claims

A rotor shaft system (100) for a vehicle (10), comprising: a rotor shaft (102) having a first shaft end (110) opposite a second shaft end (112) and having a first segment (116) and a second segment (118) defined between the first shaft end (110) and the second shaft end (112); a shaft gear (114) coupled to the rotor shaft (102) between the first shaft end (110) and the first segment (116); a shaft sleeve (104) coupled to the first segment to surround a portion of the shaft gear (114); and a lubrication system (108) at least partially defined by the rotor shaft (102) and the shaft sleeve (104), wherein the lubrication system (108) is configured to supply a fluid (F) to at least a portion of the rotor shaft (102) and the shaft sleeve (104).The rotor shaft system (100) of claim 1, wherein the rotor shaft (102) includes a first shaft bore (122) defined from the first shaft end (110) by the first segment (116) and at least a portion of the second segment (118), and wherein the first shaft bore (122) is in fluid communication with the lubrication system (108).The rotor shaft system (100) of claim 2, wherein the lubrication system (108) includes a transverse bore (150) defined by the second segment (118) in fluid communication with the first shaft bore (122).The rotor shaft system (100) of claim 3, wherein the second segment (118) includes a spline (148) axially defined on an outer periphery of the second segment (118), and wherein the transverse bore (150) is in fluid communication with the spline (148).The rotor shaft system (150) of claim 4, wherein the spline (148) is configured to couple the rotor shaft (102) to a rotor (52) associated with an electric motor (50) of the vehicle (10), wherein a lubrication conduit (144) is defined by a portion of the first segment (116) and the second segment (118) and is in fluid communication with the spline (148), and wherein the shaft sleeve (104) comprises a sleeve lubrication bore (146) in fluid communication with the lubrication conduit (144).The rotor shaft system (100) of claim 1, wherein the shaft sleeve (104) encloses a recessed area (138) defined in the first segment (116) adjacent the shaft gear (114).The rotor shaft system (100) of claim 1, wherein the first segment (116) has a first diameter (D1) that is greater than a second diameter (D2) of the second segment (118).The rotor shaft system (100) of claim 1, further comprising a shaft collar (106) connected to the second segment (118) proximate the second shaft end (112).The rotor shaft system (100) of claim 8, wherein: the second segment (118) includes a feed groove (154); and the shaft collar (106) has at least one opening (200) in fluid communication with the feed groove (154).A vehicle (10) comprising: an electric motor (50) having a rotor (52); The rotor shaft system (100) of claim 1, coupled to the electric motor (50), wherein the rotor shaft system (100) comprises the second segment (118) coupled to the rotor (52), the shaft sleeve (104) coupled to the first segment (116) so as to be disposed between the shaft gear (114) and the rotor (52), a shaft collar (106) coupled to the second segment (118) between the rotor (52) and the second shaft end (112), wherein the shaft collar (106) is configured to clamp the rotor (52) and the shaft sleeve (104) to the rotor shaft (102), and the lubrication system (108) is configured to supply the fluid (F) to at least the portion of the rotor shaft (102), the shaft sleeve (104), and the electric motor (50).

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