Rotor shaft system with increased stiffness

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 section and a second section defined between a first shaft end and a second shaft end. The rotor shaft system includes a shaft gear coupled to the rotor shaft between the first shaft end and the first section, and a shaft sleeve coupled to the first section so as to surround a portion of the shaft gear. The rotor shaft system includes a lubrication system defined at least partially through the rotor shaft and the shaft sleeve. A lubrication system is used to supply fluid to at least a portion of the rotor shaft and the shaft sleeve.

Description

[0001] TECHNICAL FIELD The present invention relates generally to propulsion systems for vehicles, and more particularly to propulsion systems for vehicles having a rotor shaft system with increased stiffness. Background Art

[0002] Typically, a propulsion system for a vehicle, such as a hybrid electric vehicle or an electric vehicle, may include an electric motor. The electric motor supplies power to a transmission system, which in turn transmits power from the propulsion system to one or more wheels. In some examples, it is desirable to increase the speed of the electric motor. In order to increase the speed of the electric motor, the size of the rotor associated with the electric motor may be reduced, which results in a corresponding reduction in the size of the rotor shaft associated with the electric motor. However, the reduction in the size of the rotor shaft may result in an increase in the flexibility of the rotor shaft. The increased flexibility of the rotor shaft may result in a reduction in the lateral stiffness of the rotor shaft, which is undesirable.

[0003] Therefore, it is desirable to provide a rotor shaft system for an electric motor with increased stiffness that provides a rotor shaft that enables the speed of the electric motor to be increased without affecting the lateral stiffness of the rotor shaft. Moreover, other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. Summary of the invention

[0004] 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 to a second shaft end. The rotor shaft has a first section and a second section defined between the first shaft end and the second shaft end. The rotor shaft system includes a shaft gear and a shaft sleeve, the shaft gear is coupled to the rotor shaft between the first shaft end and the first section, and the shaft sleeve is coupled to the first section so as to surround a portion of the shaft gear. The rotor shaft system includes a lubrication system, which is defined as at least partially passing through the rotor shaft and the shaft sleeve. The lubrication system is configured to supply fluid to at least a portion of the rotor shaft and the shaft sleeve.

[0005] The rotor shaft includes a first shaft hole, which is defined as passing through the first section and at least a portion of the second section from the first shaft end, and the first shaft hole is in fluid communication with the lubrication system. The lubrication system includes a transverse hole defined as passing through the second section, which is in fluid communication with the first shaft hole. The second section includes a keyway axially defined on the outer periphery of the second section, and the transverse hole is in fluid communication with the keyway. The keyway is configured to couple the rotor shaft to a rotor associated with an electric motor of the vehicle. The lubrication conduit is defined as passing through a portion of the first section and the second section, and is in fluid communication with the keyway. The shaft sleeve includes a sleeve lubrication hole in fluid communication with the lubrication conduit. The shaft sleeve enclosure is defined in a recessed area adjacent to the shaft gear in the first section. The first section has a first diameter, which is greater than the second diameter of the second section. The rotor shaft system includes a shaft collar, which is coupled to the second section, near the second shaft end. The second section includes a feed groove, and the shaft collar includes at least one opening in fluid communication with the feed groove.

[0006] A vehicle is also provided according to various embodiments. The vehicle includes an electric motor and a rotor shaft system, the electric motor including a rotor, the rotor shaft system being coupled to the electric motor. The rotor shaft system includes a rotor shaft having a first shaft end opposite to a second shaft end. The rotor shaft has a first section and a second section defined between the first shaft end and the second shaft end. The second section is coupled to the rotor. The rotor shaft system includes a shaft gear defined on the rotor shaft between the first shaft end and the first section. The rotor shaft system includes a shaft sleeve coupled to the first section so as to be disposed between the shaft gear and the rotor, and the shaft sleeve surrounds a portion of the shaft gear. The rotor shaft system includes a shaft collar coupled to the second section 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 as passing through a portion of the rotor shaft and the shaft sleeve. The lubrication system is configured to supply fluid to at least a portion of the rotor shaft, the shaft sleeve, and the electric motor.

[0007] The rotor shaft includes a first shaft hole, which is defined as extending from the first shaft end through the first section and at least a portion of the second section, and the first shaft hole is in fluid communication with the lubrication system. The lubrication system includes a transverse hole defined as passing through the second section, the transverse hole being in fluid communication with the first shaft hole. The second section includes a keyway axially defined on the outer periphery of the second section, the keyway being coupled to a key associated with the rotor, and the transverse hole being in fluid communication with the keyway. A lubrication conduit is defined as passing through a portion of the first section and the second section, and the lubrication conduit is in fluid communication with the keyway. The shaft sleeve includes a sleeve lubrication hole, and the sleeve lubrication hole is in fluid communication with the lubrication conduit. The shaft sleeve enclosure is defined in a recessed area adjacent to the shaft gear in the first section. The first section has a first diameter, the first diameter being greater than a second diameter of the second section. The second section 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, which is coupled to the second shaft hole at the second shaft end, and the second shaft hole extends axially toward the second section. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Exemplary embodiments will be described below with reference to the following drawings, wherein like reference numerals represent like elements, and wherein:

[0009] Figure 1 is a functional block diagram illustrating a vehicle including a rotor shaft system with increased stiffness according to various embodiments;

[0010] Figure 2 is a front perspective view of a rotor shaft system coupled to an electric motor associated with a propulsion system of a vehicle according to various embodiments;

[0011] Figure 3 It is along Figure 2 A cross-sectional view of the rotor shaft system and the electric motor taken along line 3-3;

[0012] Figure 4 is a rear perspective view of a rotor shaft system coupled to an electric motor according to various embodiments;

[0013] Figure 5 is an exploded view of a rotor shaft system and an electric motor according to various embodiments; and

[0014] Figure 6 is with Figure 1 Another exemplary rotor shaft system and electric motor for use with a vehicle Figure 2 A cross-sectional view taken along line 3-3. DETAILED DESCRIPTION

[0015] The following detailed description is merely exemplary in nature and is not intended to limit application and use. In addition, there is no intention to be bound by any express or implied theory presented in the preceding introduction, the invention summary, 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 (ASICs), electronic circuits, processors (shared, dedicated or groups) and memories that execute one or more software or firmware programs, combinational logic circuits, and / or other appropriate components that provide the described functions.

[0016] Embodiments of the present disclosure may be described herein in terms of functions and / or logic block components and various processing steps. It should be understood that such block components may be implemented by any number of hardware, software, and / or firmware components configured to perform a specified function. For example, embodiments of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, etc., which may perform various functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and the systems described herein are merely exemplary embodiments of the present disclosure.

[0017] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, machine learning models, radar, lidar, image analysis, and other functional aspects of the system (and the various operating components of the system) may not be described in detail herein. In addition, the connecting lines shown in the various figures included herein are intended to represent example functional relationships and / or physical connections between various elements. It should be noted that many alternative or additional functional relationships or physical connections may exist in the embodiments of the present disclosure.

[0018] As used herein, the term "axial" refers to a direction that is roughly parallel to or coincident with the axis of rotation, axis of symmetry, or centerline of one or more components. For example, in a cylinder or disk having a centerline and generally circular ends or opposing faces, the "axial" direction may refer to a direction that extends roughly parallel to the centerline between the opposing ends or faces. In some cases, the term "axial" may be used with respect to components that are not cylindrical (or otherwise radially symmetrical). For example, the "axial" direction of a rectangular housing containing a rotating axis may be considered to be a direction that is roughly parallel to or coincident with the axis of rotation of the axis. In addition, the term "radial" as used herein may refer to, for example, in a plane perpendicular to the centerline or axis of a cylinder or disk, the direction or relationship of a component relative to a line extending outward from a shared centerline, axis, or similar reference. In some cases, components may be considered to be "radially" aligned even if one or both of the components may not be cylindrical (or otherwise radially symmetrical). In addition, the terms "axial" and "radial" (and any derivatives) may encompass directional relationships that are not precisely aligned (e.g., skewed) with the true axial and radial dimensions, provided that the relationship is primarily in the corresponding nominal axial or radial direction. As used herein, the term "approximately" means within 10% to account for manufacturing tolerances. In addition, the term "substantially" means within 10% to account for manufacturing tolerances.

[0019] refer to Figure 1 According to various embodiments, a rotor shaft system having increased stiffness, generally shown at 100, is associated with a vehicle 10. In one example, the vehicle 10 is a battery electric vehicle, however, it should be understood that the following disclosure may be applicable to other electric motor driven devices. Figure 1 As shown, the vehicle 10 generally includes a chassis 12, a body 14, a front wheel 16, and a rear wheel 18. The body 14 is arranged on the chassis 12 and substantially encloses the components of the vehicle 10. The body 14 and the chassis 12 can form a frame together. The wheels 16-18 are each rotatably connected to the chassis 12 near the corresponding corners 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 can be implemented in other non-autonomous systems and is not limited to this embodiment. The vehicle 10 is depicted as a battery electric passenger car in the illustrated embodiment, but it should be understood that any other vehicle may also be used, including motorcycles, trucks, sports utility vehicles (SUVs), recreational vehicles (RVs), etc.

[0020] 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. In various embodiments, the propulsion system 20 may include an electric motor, such as an electric motor. The propulsion system 20 is coupled to a rotor shaft system 100, which is coupled to the transmission system 22. The transmission system 22 is configured to transmit power from the propulsion system 20 received via the rotor shaft system 100 to the wheels 16 and 18 according to a selectable speed ratio. According to various embodiments, the transmission system 22 may include a stepped ratio automatic transmission, a continuously variable transmission, or other suitable transmission.

[0021] Braking system 26 is configured to provide braking torque to wheels 16 and 18. In various embodiments, braking system 26 may include friction brakes, brake-by-wire brakes, a regenerative braking system (such as an electric motor), and / or other suitable braking systems.

[0022] The steering system 24 affects the position of the wheels 16 and / or 18. Although depicted as including a steering wheel 24a for purposes of illustration, in some embodiments contemplated within the scope of the present disclosure, the steering system 24 may not include a steering wheel.

[0023] The sensor system 28 includes one or more sensing devices 40a-40n that sense observable conditions of the external environment and / or the internal environment of the vehicle 10. In various embodiments, the sensing devices 40a-40n include, but are not limited to, radar (e.g., long-range, medium-range-short-range), lidar, global positioning system, optical camera (e.g., forward, 360 degrees, rearward, side, stereo, etc.), thermal (e.g., infrared) camera, ultrasonic sensor, odometer sensor (e.g., encoder), and / or other sensors that can be used in conjunction with the systems and methods according to the present subject matter. In one example, the sensing devices 40a-40n may include a shaft speed sensor 40a that is coupled to the rotor shaft system 100 and is configured to generate a sensor signal based on the speed of the rotor shaft 102 associated with the rotor shaft system 100. The sensor system 28 communicates with the controller 34 via a communication medium.

[0024] The actuator system 30 includes one or more actuator devices 42a-42n that control one or more vehicle features such as, but not limited to, the propulsion system 20, the transmission system 22, the steering system 24, and the braking system 26. In various embodiments, the vehicle 10 may also include Figure 1 Interior and / or exterior vehicle features shown in the figure, such as various doors, trunks, and cabin features, such as air components, music components, lighting components, touch screen display components, active safety seats or tactile seats, etc.

[0025] The controller 34 includes at least one processor 44 and a computer readable storage device or medium 46. The processor 44 can 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), a secondary processor in a number of processors associated with the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), any combination thereof, or any device generally used to execute instructions. The computer readable storage device or medium 46 can include volatile and non-volatile storage in, for example, 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 when the processor 44 is powered off. The computer readable storage device or medium 46 may be implemented using any of a variety of known memory devices, such as a PROM (programmable read-only memory), an EPROM (electrical PROM), an EEPROM (electrically erasable PROM), flash memory, or any other electrical, magnetic, optical, or combination memory device capable of storing data, some of which represent executable instructions used by the controller 34 to control the vehicle 10.

[0026] refer to Figure 2 , showing the propulsion system 20 and the rotor shaft system 100 in more detail. As discussed, in this example, the propulsion system 20 is an electric motor 50, and it can have any suitable configuration for use with the vehicle 10. Briefly, referring to Figure 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 can be supported for rotation by one or more bearings (not shown). The electric motor 50 can be contained between a pair of motor end rings 60, and the output shaft 56 can extend outward from each motor end ring 60.

[0027] In this example, each motor end ring 60 is annular and each motor end ring 60 is substantially mirror-symmetrical about an axis perpendicular to the longitudinal axis L of the rotor shaft system 100. Each motor end ring 60 defines a central hole 62 and includes a countersunk area 64 defined around the central hole 62. The central hole 62 is sized to receive a portion of the rotor shaft system 100 therethrough. The countersunk area 64 extends radially around the central hole 62. The countersunk area 64 provides a contact surface 64a for coupling the rotor shaft system 100 to the propulsion system 20. Return to Reference Figure 2and Figure 4 Each motor end ring 60 may also include one or more openings 66 defined as a perimeter or circumference around the corresponding motor end ring 60, spaced apart from the countersunk area 64, and receiving corresponding mechanical fasteners, such as bolts, screws, etc., to connect each motor end ring 60 to the stator 54.

[0028] In one example, the rotor shaft system 100 includes a rotor shaft 102, a shaft sleeve 104, a shaft sleeve ring 106 ( Figure 4 ) and a lubrication system 108. The rotor shaft 102 is composed of a metal or a metal alloy and is cast, forged, extruded, additively manufactured, etc. The rotor shaft 102 is substantially cylindrical and extends along a longitudinal axis L. The longitudinal axis L is also the axis of rotation of the rotor shaft 102. The rotor shaft 102 includes a first shaft end 110 opposite to a second shaft end 112, a shaft gear 114, a first section or sleeve section 116, a second section or rotor section 118, and a third section or coupling section 120. The rotor shaft 102 also defines a first shaft hole 122 and a second shaft hole 124. Reference Figure 3 , the first shaft end 110 defines a first countersunk hole 130 that communicates with the first shaft hole 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 can be coupled to a bearing, such as a ball bearing (not shown), that supports the rotor shaft 102 for rotation. The second shaft end 112 defines a second countersunk hole 134 that communicates with the second shaft hole 124.

[0029] The shaft gear 114 is defined on the rotor shaft 102, for example, by machining with a lathe. The shaft gear 114 is a pinion gear having a plurality of gear teeth 136. In this example, the shaft gear 114 is a helical pinion gear having a plurality of helical gear teeth. It should be noted that the shaft gear 114 can be formed on the rotor shaft 102 as needed to mate with the transmission system 22. For example, the shaft gear 114 can be defined as a spur gear having a plurality of spur gear teeth, a bevel gear having a plurality of bevel gear teeth, etc. Typically, the shaft gear 114 is coupled to or meshingly engaged with a mating gear M of the transmission system 22 to transfer torque from the propulsion system 20 to the transmission system 22 ( Figure 3 ). The shaft gear 114 can have any number of gear teeth 136 to couple to the transmission system 22 to drive the transmission system 22, and therefore, the number of gear teeth 136 shown herein is only an example. The shaft gear 114 is defined on the rotor shaft 102 between the first shaft end 110 and the sleeve section 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).

[0030] The sleeve section 116 is defined on the rotor shaft 102, directly adjacent to the shaft gear 114. The sleeve section 116 is defined between the shaft gear 114 and the rotor section 118. Generally, the shaft sleeve 104 is coupled to the rotor shaft 102 so as to be positioned on and coupled to the sleeve section 116. The sleeve section 116 includes a portion of the recessed area 138, the lubrication groove 142, and the lubrication conduit 144. The recessed area 138 is defined near or adjacent to the shaft gear 114. The recessed area 138 enables the removal of debris (such as metal chips, etc.) generated during the formation of the shaft gear 114 from the rotor shaft 102. In other words, the recessed area 138 serves as a cleaning area. The remainder of the sleeve section 116 has a first diameter, the size and shape of which are set to couple the shaft sleeve 104 to the rotor shaft 102. In one example, the first diameter D1 is about 38.5 millimeters (mm) to about 40.5 millimeters (mm). The remainder of the sleeve segment 116 extends axially a distance to achieve alignment between the lubrication groove 142 and the sleeve lubrication hole 146. The lubrication groove 142 is coupled to and in fluid communication with the sleeve lubrication hole 146 and the lubrication conduit 144. The lubrication groove 142 is defined along an axis substantially perpendicular to the longitudinal axis L, or radially relative to the rotor shaft 102. As will be discussed, the lubrication groove 142 guides a fluid F (such as a lubrication fluid and / or a cooling fluid, for example, oil) to the sleeve lubrication hole 146 of the shaft sleeve 104. As will be discussed, the lubrication conduit 144 extends from the lubrication groove 142 of the sleeve segment 116 along the rotor shaft 102 to near the second shaft end 112. The lubrication conduit 144 is coupled to or in fluid communication with the lubrication groove 142 to supply or guide the fluid F into the lubrication groove 142.

[0031] The rotor section 118 is defined as extending from the sleeve section 116 to the coupling section 120. The rotor section 118 has a second diameter D2 that is different from and smaller than the first diameter D1 of the sleeve section 116. The shoulder 147 is defined between the step or change in diameter of the rotor shaft 102 from the sleeve section 116 to the rotor section 118. In one example, the second diameter D2 is approximately 36 millimeters (mm) to approximately 38 millimeters (mm). The rotor section 118 is coupled to the rotor 52 of the electric motor 50. In this example, the rotor section 118 includes a keyway 148 and a cross hole 150. The keyway 148 is defined as extending axially along the outer surface or perimeter of the rotor section 118 and cooperating with a key 152 defined on the rotor 52. The cooperation between the keyway 148 and the key 152 couples the rotor shaft 102 to the rotor 52 to enable torque transfer between the rotor 52 and the rotor shaft 102. In Figure 314, the key 152 is shown as being in the keyway 148. Thus, generally, 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 sleeve ring 106 may also facilitate coupling the rotor shaft 102 to the rotor 52 along the rotor segment 118. The cross bore 150 is defined to be substantially equidistant from the pair of motor end rings 60. The cross bore 150 is substantially cylindrical and extends along an axis 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 conduit 144 to direct the fluid F into the lubrication conduit 144. The cross bore 150 is also in fluid communication with the keyway 148 to supply the fluid F to the keyway 148.

[0032] In one example, the rotor segment 118 further includes a feed slot 154. The feed slot 154 is defined around the outer perimeter or circumference of the rotor segment 118, proximate the coupling segment 120. The feed slot 154 is in fluid communication with or fluidly coupled to the keyway 148 to receive the fluid F from the keyway 148. The feed slot 154 provides or supplies the fluid F to the motor end ring 60 proximate the second shaft end 112 and to the shaft collar 106.

[0033] The coupling section 120 is defined between the rotor section 118 and the second shaft end 112. In one example, the coupling section 120 has a third diameter that is different from and smaller than the second diameter D2 of the rotor section 118. The coupling section 120 is sized to receive a bearing, such as a ball bearing. In this example, the coupling section 120 includes a coupling groove 156. The size and shape of the coupling groove 156 are set to facilitate coupling the bearing to the rotor shaft 102 to support the rotor shaft 102 for rotation. The coupling groove 156 is defined to be substantially equidistant between the rotor section 118 and the second shaft end 112.

[0034] The first axial hole 122 is defined through the first axial end 110 to extend from the first axial end 110 through the sleeve section 116 and a portion of the rotor section 118. The first axial hole 122 generally extends through the rotor section 118 so that the inner end 122a of the first axial hole 122 is substantially coplanar with the motor end ring 60 proximate the second axial end 112. The first axial hole 122 is separate and discrete from the second axial hole 124. The first axial hole 122 is fluidly coupled to or in fluid communication with a source 160 of the fluid F and provides the first axial hole 122 with the fluid F. In one example, the first axial hole 122 includes a ledge 122b defined downstream of the cross hole 150. The ledge 122b is an increase or decrease in the inner diameter of the first axial hole 122, which helps move the fluid F through the first axial hole 122.

[0035] The second shaft hole 124 is defined through the second shaft end 112 to extend from the second shaft end 112 to an inner end 124a defined within the coupling section 120 adjacent the rotor section 118. The second shaft hole 124 defines a plurality of internal threads 158. The internal threads 158 are coupled to or matingly engage with mechanical fasteners such as clamp bolts, which can be used to couple the shaft speed sensor 40a of the sensor system 28 to the rotor shaft 102.

[0036] The shaft sleeve 104 surrounds the sleeve section 116 of the rotor shaft 102. The shaft sleeve 104 is composed of a metal or a metal alloy and is cast, forged, additively manufactured, etc. The shaft sleeve 104 is substantially cylindrical and has a first sleeve end 170 opposite to a second sleeve end 172. The shaft sleeve 104 also defines a sleeve lubrication hole 146 and a central shaft hole 176. The central shaft hole 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 coupled to the sleeve section 116. In one example, the shaft sleeve 104 is coupled to the sleeve section 116 by a press fit or a shrink fit. The first sleeve end 170 and the second sleeve end 172 each have a diameter that is different from and smaller 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. Typically, the sleeve diameter D is sized to increase the 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 the resistance to deflection or bending of the rotor shaft 102 along the longitudinal axis L. By increasing the lateral stiffness of the rotor shaft 102, the shaft sleeve 104 helps maintain the shaft gear 114 in a substantially parallel relationship with the mating gear M of the transmission system 22, which ensures efficient torque transfer from the rotor shaft 102 to the transmission system 22. In other words, the increased lateral stiffness maintains the central axis A1 defined through the shaft gear 114 substantially coaxial with the longitudinal axis L, which ensures that the central axis A1 of the shaft gear 114 is substantially parallel to the central axis A2 of the mating gear M of the transmission system 22. In one example, the increased lateral stiffness of the rotor shaft 102 reduces the misalignment or misaligned line of action (MLOA) of the shaft gear 114 and the mating gear M by 2 to 3 times. It should be noted that sleeve diameter D is merely an example, as sleeve diameter D may be increased or decreased to impart a predetermined amount of lateral stiffness to rotor shaft 102 to maintain a substantially parallel relationship between shaft gear 114 and mating gear M of transmission system 22 .

[0037] The first sleeve end 170 is coupled to the rotor shaft 102 so as to be positioned around and over a portion of the gear teeth 136 of the shaft gear 114. Thus, in this example, the shaft sleeve 104 overlaps, surrounds, or encloses the recessed area 138 of the sleeve segment 116. The first sleeve end 170 is coupled to the rotor shaft 102 around the gear teeth 136 so as not to interfere with the coupling of the gear teeth 136 to the transmission system 22. The second sleeve end 172 is coupled to and in contact with the motor end ring 60 proximate the sleeve segment 116. The second sleeve end 172 also overlaps or surrounds the shoulder 147 defined by the diameter difference between the sleeve segment 116 and the rotor segment 118. Typically, the shaft sleeve 104 is retained on the rotor sleeve segment via a press fit or shrink fit and is prevented from axial movement by the shaft gear 114 and the adjacent motor end ring 60.

[0038] The sleeve lubrication hole 146 is a transverse hole defined through the body 178 of the shaft sleeve 104. The sleeve lubrication hole 146 is fluidly coupled to or in fluid communication with the lubrication groove 142. The sleeve lubrication hole 146 receives the fluid F from the lubrication groove 142 and directs the fluid F radially outward, where the fluid F can flow onto the outer surface of the shaft sleeve 140 and onto the adjacent motor end ring 60.

[0039] The shaft collar 106 helps to retain the electric motor 50 on the rotor shaft 102. In one example, the cross-section of the shaft collar 106 is substantially L-shaped. The shaft collar 106 is composed of a metal or a metal alloy and is cast, stamped, additively manufactured, etc. The shaft collar 106 includes a first collar end 190 opposite a second collar end 192 and defines a central collar hole 194 extending from the first collar end 190 to the second collar end 192. The first collar end 190 includes a flange 196 that extends radially outward from the first collar end 190. The flange 196 includes a coupling surface 196a that is coupled to the motor end ring 60 proximate the second shaft end 112. In one example, reference Figure 4 , the shaft collar 106 is coupled to the motor end ring 60 by swaging. The flange 196 defines a plurality of dimples 198 at intersections 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 dimples 198 engage grooves defined on the motor end ring 60 proximate the second shaft end 112 to facilitate coupling the shaft collar 106 to the electric motor 50. It should be noted that other techniques may be used to couple the shaft collar 106 to the rotor shaft 102.

[0040] When the shaft collar 106 is coupled to the rotor shaft 102, the second collar end 192 is positioned adjacent to the coupling section 120. The central collar hole 194 is sized to receive the rotor shaft 102 and is coupled to the rotor shaft 102 for rotation therewith. The shaft collar 106 also defines a plurality of openings 200. The openings 200 are defined through the collar body 202 so as to be spaced apart around the perimeter of the collar body 202. The openings 200 are fluidly coupled to or in fluid communication with the feed slot 154 to receive the rotor shaft 102 from the keyway 148 ( Figure 3 ) receiving fluid F.

[0041] refer to Figure 3 The lubrication system 108 is in fluid communication with or fluidly coupled to a source 160 of fluid F via one or more conduits, hydraulic couplings, etc. The source 160 may include a container that receives fluid F from the vehicle 10 ( Figure 1 ) A reservoir of a fluid F associated with the rotor shaft 102, such as an oil reservoir, which may include a pump or the like to deliver the fluid F to the rotor shaft 102. In one example, the lubrication system 108 includes the first shaft hole 122, a cross hole 150 defined in the rotor segment 118, a lubrication conduit 144 defined in the rotor segment 118 and the sleeve segment 116, a lubrication groove 142 defined in the sleeve segment 116, a sleeve lubrication hole 146 defined in the shaft sleeve 104, a feed groove 154 defined in the rotor segment 118, and an opening 200 of the shaft collar 106.

[0042] Typically, fluid F is supplied from source 160 to first axial bore 122. Fluid F flows from first axial bore 122 to cross bore 150. Fluid F flows from cross bore 150 through keyway 148 to feed slot 154. Fluid F flows from feed slot 154 through opening 200 of collar to lubricate bearings coupled to coupling section 120.

[0043] The fluid F also flows from the cross hole 150 along the keyway 148 and / or the lubrication conduit 144 into the portion of the lubrication conduit 144 defined in the sleeve section 116. The fluid F flows from the lubrication conduit 144 into the lubrication groove 142, and from the lubrication groove 142 into the sleeve lubrication hole 146. The fluid F flows from the sleeve lubrication hole 146 through the outer surface of the body 178 and onto the motor end ring 60 near 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 can be lubricated and / or cooled without the need for additional components.

[0044] It should be noted that although the rotor shaft 102 is described herein as including the shaft gear 114 having the recessed area 138, the rotor shaft 102 may be configured differently to increase the lateral thickness of the rotor shaft 102. In one example, referring to Figure 6, shows a rotor shaft system 300 that can be coupled to the rotor 52 and rotate with the rotor 52. Because the rotor shaft system 300 includes Figures 1 to 5 The components of the rotor shaft system 100 discussed are the same or similar components, so the same reference numerals will be used to represent the same or similar components. In one example, the rotor shaft system 300 includes a rotor shaft 302, a shaft sleeve 104, a shaft collar 106, and a lubrication system 108. The rotor shaft 302 is composed of a metal or a metal alloy and is cast, forged, extruded, additively manufactured, etc. The rotor shaft 302 is substantially cylindrical and extends along a longitudinal axis L. The longitudinal axis L is also the axis of rotation of the rotor shaft 302. The rotor shaft 302 includes a first shaft end 110 opposite to the second shaft end 112, a shaft gear 314, a first section or sleeve section 316, a second section or rotor section 118, and a third section or coupling section 120. The rotor shaft 302 also defines a first shaft hole 122 and a second shaft hole 124. The first shaft end 110 defines a first countersunk hole 130, which is connected to the first shaft hole 122. The first shaft end 110 also includes a chamfer 132. The first shaft end 110 may be coupled to a bearing, such as a ball bearing (not shown), that supports the rotor shaft 302 for rotation. The second shaft end 112 defines a second countersunk bore 134 that communicates with the second shaft bore 124.

[0045] The shaft gear 314 is defined on the rotor shaft 302, for example, by machining with a lathe. The shaft gear 314 is a pinion gear having a plurality of gear teeth 336. In this example, the shaft gear 314 is a helical pinion gear having a plurality of helical gear teeth. It should be noted that the shaft gear 314 can be formed on the rotor shaft 302 as needed to mate with the transmission system 22 ( Figure 1 ) are matched. For example, the shaft gear 314 can be defined as a spur gear having a plurality of spur gear teeth, a bevel gear having a plurality of bevel gear teeth, etc. Typically, the shaft gear 314 is coupled to or meshingly engaged with a mating gear 24 of the transmission system 22 to transfer torque from the propulsion system 20 to the transmission system 22 ( Figure 3 ). The shaft gear 314 can have any number of gear teeth 336 to couple to the transmission system 22 to drive the transmission system 22, and therefore, the number of gear teeth 336 shown herein is only an example. The shaft gear 314 is defined on the rotor shaft 302 between the first shaft end 110 and the sleeve section 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).

[0046] The sleeve section 316 is defined on the rotor shaft 302, directly adjacent to the shaft gear 314. The sleeve section 316 is defined between the shaft gear 314 and the rotor section 118. Generally, the shaft sleeve 104 is coupled to the rotor shaft 302 so as to be positioned on and coupled to the sleeve section 316. The sleeve section 316 includes a portion of a sweep out area 338, a lubrication groove 142, and a lubrication conduit 144. The sweep out area 338 is defined during the formation of the shaft gear 314. The sweep out area 338 generally includes a shallow depth gear tooth 336, which is defined as a lathe for forming the shaft gear 314. The remainder of the sleeve section 316 has a first diameter D1, which is sized and shaped to couple the shaft sleeve 104 to the rotor shaft 302. The remainder of the sleeve segment 116 is axially extended a distance to achieve alignment between the lubrication groove 142 and the sleeve lubrication hole 146. The lubrication groove 142 is coupled to and in fluid communication with the sleeve lubrication hole 146 and the lubrication conduit 144. The lubrication conduit 144 is coupled to or in fluid communication with the lubrication groove 142 to supply or guide the fluid F into the lubrication groove 142.

[0047] The rotor section 118 is defined as extending from the sleeve section 316 to the coupling section 120. The rotor section 118 has a second diameter D2 that is different from and smaller than the first diameter D1 of the sleeve section 116. The shoulder 147 is defined between the step or change in diameter of the rotor shaft 302 from the sleeve section 316 to the rotor section 118. The rotor section 118 is coupled to the rotor 52 of the electric motor 50. The rotor section 118 includes a keyway 148 and a cross hole 150. In Figure 6 14, the key 152 is shown as being in the keyway 148. 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 facilitate coupling the rotor shaft 302 to the rotor 52 along the rotor segment 118. The cross hole 150 is in fluid communication with or fluidly coupled to the first shaft hole 122 to receive the fluid F, and the cross hole 150 is in fluid communication with or fluidly coupled to the lubrication conduit 144 to guide the fluid F into the lubrication conduit 144. The cross hole 150 is also in fluid communication with the keyway 148 to supply the fluid F to the keyway 148. In one example, the rotor segment 118 further includes a feed slot 154. The feed slot 154 is in fluid communication with or fluidly coupled to the keyway 148 to receive the fluid F from the keyway 148. The feed groove 154 provides or supplies the fluid F to the motor end ring 60 proximate the second shaft end 112 and to the shaft collar 106 .

[0048] Coupling section 120 is defined between rotor section 118 and second shaft end 112. Coupling section 120 includes coupling slot 156 sized and shaped to facilitate coupling a bearing to rotor shaft 302 to support rotor shaft 302 for rotation.

[0049] The first shaft hole 122 is defined through the first shaft end 110 to extend from the first shaft end 110 through the sleeve section 316 and a portion of the rotor section 118. The first shaft hole 122 is fluidly coupled to or in fluid communication with a source 160 of the fluid F and the first shaft hole 122 is provided with the fluid F. In one example, the first shaft hole 122 includes a step or lug 122b defined downstream of the cross hole 150.

[0050] The second shaft hole 124 is defined through the second shaft end 112 to extend from the second shaft end 112 to the inner end 124a. The second shaft hole 124 defines internal threads 158 that can be used to couple the shaft speed sensor 40a of the sensor system 28 to the rotor shaft 302.

[0051] The shaft sleeve 104 surrounds the sleeve section 316 of the rotor shaft 302. The central shaft hole 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 coupled to the sleeve section 316. In one example, the shaft sleeve 104 is coupled to the sleeve section 316 by a press fit or a shrink fit. The first sleeve end 170 and the second sleeve end 172 each have a diameter that is different from and smaller than a sleeve diameter D of the 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 increase the lateral stiffness of the rotor shaft 302 and is larger than the gear diameter GD associated with the shaft gear 114. In one example, the sleeve diameter D is equal to or smaller than the motor diameter MD associated with the electric motor 50. By increasing the lateral stiffness of rotor shaft 302 , shaft sleeve 104 helps maintain shaft gear 314 in a substantially parallel relationship with mating gear M of drive train 22 , which ensures efficient torque transfer from rotor shaft 302 to drive train 22 .

[0052] The first sleeve end 170 is coupled to the rotor shaft 302 so as to be positioned around and over a portion of the gear teeth 336 of the shaft gear 314. Thus, in this example, the shaft sleeve 104 overlaps, surrounds, or encloses the swept-out area 338 of the sleeve segment 316. The first sleeve end 170 is coupled to the rotor shaft 302 around the gear teeth 336 so as not to interfere with the coupling of the gear teeth 336 to the drive train 22 and to facilitate 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 to the sleeve segment 316. The second sleeve end 172 also overlaps or surrounds the shoulder 147 defined by the diameter difference between the sleeve segment 316 and the rotor segment 118. Typically, the shaft sleeve 104 is retained on the rotor sleeve segment via a press fit or shrink fit and is prevented from axial movement by the shaft gear 314 and the adjacent motor end ring 60. The sleeve lubrication bore 146 is fluidly coupled to or in fluid communication with the lubrication groove 142 .

[0053] The shaft collar 106 helps retain the electric motor 50 on the rotor shaft 302. The shaft collar 106 includes a first collar end 190 opposite a second collar end 192 and defines a central collar hole 194. The first collar end 190 includes a flange 196 including a coupling surface 196a that couples to the motor end ring 60 proximate the second shaft end 112. The shaft collar 106 is coupled to the motor end ring 60 by swaging. The flange 196 defines a plurality of dimples 198 that engage with grooves defined on the motor end ring 60 proximate the second shaft end 112 to facilitate coupling the shaft collar 106 to the electric motor 50. It should be noted that other techniques may be used to couple the shaft collar 106 to the rotor shaft 302.

[0054] When the shaft collar 106 is coupled to the rotor shaft 302, the second collar end 192 is positioned adjacent the coupling segment 120. The central collar hole 194 is sized to receive the rotor shaft 302 and is coupled to the rotor shaft 302 for rotation therewith. The shaft collar 106 also defines a plurality of openings 200 that are fluidly coupled to or in fluid communication with the feed slot 154 to receive the fluid F from the keyway 148.

[0055] The lubrication system 108 is in fluid communication with or fluidly coupled to a source 160 of fluid F via one or more conduits, hydraulic couplings, etc. The lubrication system 108 includes the first shaft bore 122, the cross bore 150 defined in the rotor segment 118, the lubrication conduit 144 defined in the rotor segment 118 and 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 opening 200 of the shaft collar 106.

[0056] Typically, fluid F is supplied from source 160 to first axial bore 122. Fluid F flows from first axial bore 122 to cross bore 150. Fluid F flows from cross bore 150 through keyway 148 to feed slot 154. Fluid F flows from feed slot 154 through opening 200 of collar to lubricate bearings coupled to coupling section 120.

[0057] The fluid F also flows from the cross hole 150 along the keyway 148 and / or the lubrication conduit 144 into the portion of the lubrication conduit 144 defined in the sleeve section 316. The fluid F flows from the lubrication conduit 144 into the lubrication groove 142, and from the lubrication groove 142 into the sleeve lubrication hole 146. The fluid F flows from the sleeve lubrication hole 146 through the outer surface of the body 178 and onto the motor end ring 60 near 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 can be lubricated and / or cooled without the need for additional components.

[0058] In one example, reference Figure 3 and Figure 6 In order to assemble the rotor shaft system 100, 300 with the electric motor 50, the first shaft hole 122 and the second shaft hole 124 can be drilled or machined in the rotor shaft 102, 302 when the rotor shaft 102, 302 is formed. The cross hole 150 can be drilled through the rotor segment 118, and the feed groove 154 can be machined through the rotor segment 118. In the example of the rotor shaft 102, the recessed area 138 is defined in the sleeve segment 116. The lubrication groove 142 and the lubrication conduit 144 are defined in the rotor shaft 102, 302 via drilling, machining, etc. The keyway 148 is defined via machining to mate with the key 152 of the rotor 52. In the example of the rotor shaft 102, the shaft gear 114 is formed near the first shaft end 110, and any debris is removed from the recessed area 138. In the example of the rotor shaft 302 , the shaft gear 314 is formed proximate the first shaft end 110 , and a swept-out area 338 is defined in the sleeve section 316 during the formation of the shaft gear 314 .

[0059] With the shaft sleeve 104 formed, the sleeve lubrication hole 146 is defined through the body 178 of the shaft sleeve 104. The shaft sleeve 104 is press-fit or shrink-fit around the sleeve segment 116, 316. With the stator 54 coupled to the rotor 52 and the motor end ring 60 coupled to the stator 54 and the rotor 52, the rotor 52 is slid onto the keyway 148 of the rotor segment 118 so that the key 152 is received within the keyway 148. The pocket 198 of the shaft sleeve ring 106 is aligned with the groove of the motor end ring 60 proximate the second shaft end 112, and the shaft sleeve ring 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 to a portion of the gear teeth 136, 336, coupling the rotor 52 to the rotor shaft 102, 302 such that one of the motor end rings 60 engages with the shaft sleeve 104, and using the shaft sleeve 106 to clamp the shaft sleeve 106 to the other motor end ring 60, the clamping path for fixing the motor 50 to the rotor shaft 102, 302 is from the shaft sleeve 106, through the rotor 52, through the shaft sleeve 104 to the shaft gear 114, 314. Therefore, the shaft sleeve 104 is part of the clamping path for coupling the motor 50 to the rotor shaft 102, 302.

[0060] With the electric motor 50 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 a mating gear of the transmission 22 to transfer torque from the electric motor 50 to the transmission 22. A source 160 of fluid F may be coupled to the rotor shaft 102 via a conduit, fitting, etc. to supply fluid F to the lubrication system 108.

[0061] When the propulsion system 20 operates to supply power to the transmission system 22 to drive the wheels 16 and / or 18 of the vehicle 10, the rotor 52 rotates the rotor shaft 102, 302. The 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 supplies the fluid F to the lubrication system 108, which cools the rotor shaft 102, 302, the shaft sleeve 104, the motor end ring 60, the shaft sleeve ring 106, and the bearings coupled to the rotor shaft 102, 302 at the coupling section 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 and second diameters of the rotor shaft 102, 302 are relatively small, and together with the first and second shaft holes 122, 124, the rotor shaft 102, 302 is relatively lightweight. By providing a rotor shaft 102, 302 having a reduced diameter D1, D2 and weight, the rotor 52 can drive the rotor shaft 102, 302 at a higher speed, thereby driving the transmission system 22 at a higher speed. The reduced diameter and lighter 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 affecting the speed at which the rotor shaft 102, 302 can be driven. This ensures that the shaft gear 114, 314 maintains a substantially parallel relationship with the mating gear M of the transmission system 22 during operation, and reduces the misaligned action line between the shaft gear 114 and the mating gear M. The shaft sleeve 104 also reduces the 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 the operation of the rotor shaft 102, 302. The substantial uniformity of the diameters D1, D2 of the rotor shaft 102, 302 also reduces manufacturing complexity, and the substantially symmetrical shape of the shaft sleeve 104 reduces assembly complexity. In addition, by coupling to and surrounding a portion of the gear teeth 136, 336, the shaft sleeve 104 acts as a portion of the shaft gear 114, 314 and is prohibited from moving relative to the shaft gear 114, 314.

[0062] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a large number of variations. It should also be understood that the exemplary embodiment or multiple exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for implementing the exemplary embodiment or multiple exemplary embodiments for those skilled in the art. It should be understood that various changes may be made to the functions and arrangements of the elements without departing from the scope of the present disclosure as set forth in the attached claims and their legal equivalents.

Claims

1. A rotor shaft system for a vehicle, the rotor shaft system comprising: a rotor shaft including a first shaft end opposite a second shaft end and having a first section and a second section defined between the first shaft end and the second shaft end; a shaft gear coupled to the rotor shaft between the first shaft end and the first section; a shaft sleeve coupled to the first section so as to surround a portion of the shaft gear; and A lubrication system is defined at least partially through the rotor shaft and the shaft sleeve, the lubrication system being configured to supply fluid to at least a portion of the rotor shaft and the shaft sleeve.

2. The rotor shaft system of claim 1, wherein the rotor shaft includes a first shaft hole defined from the first shaft end through the first segment and at least a portion of the second segment, and the first shaft hole is in fluid communication with the lubrication system. 3 . The rotor shaft system of claim 2 , wherein the lubrication system includes a transverse bore defined through the second segment, the transverse bore being in fluid communication with the first shaft bore. 4 . The rotor shaft system of claim 3 , wherein the second segment includes a keyway axially defined on an outer periphery of the second segment, and the cross bore is in fluid communication with the keyway.

5. The rotor shaft system of claim 4, wherein the keyway is configured to couple the rotor shaft to a rotor associated with an electric motor of the vehicle, a lubrication conduit is defined as passing through a portion of the first segment and the second segment and in fluid communication with the keyway, and the shaft sleeve includes a sleeve lubrication hole in fluid communication with the lubrication conduit.

6. The rotor shaft system of claim 1, wherein the shaft sleeve enclosure is defined in a recessed area in the first section adjacent the shaft gear. 7 . The rotor shaft system of claim 1 , wherein the first segment has a first diameter that is greater than a second diameter of the second segment.

8. The rotor shaft system of claim 1, further comprising a shaft collar coupled to the second segment proximate the second shaft end.

9. The rotor shaft system of claim 8, wherein: The second section includes a feed trough; and The shaft collar includes at least one opening in fluid communication with the feed groove.

10. A vehicle, comprising: an electric motor, the electric motor comprising a rotor; and The rotor shaft system of claim 1, the rotor shaft system coupled to the electric motor, the rotor shaft system comprising the second section coupled to the rotor, the shaft sleeve coupled to the first section so as to be disposed between the shaft gear and the rotor, a shaft collar coupled to the second section between the rotor and the second shaft end, the shaft collar configured to clamp the rotor and the shaft sleeve to the rotor shaft, and the lubrication system configured to supply the fluid to the rotor shaft, the shaft sleeve, and at least a portion of the electric motor.

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