Rotor shaft mounted vapor chamber and heat pipe for end cap heat sink of electric machine

Abstract

An electric machine having a rotor shaft mounted heat pipe and / or vapor chamber thermally coupled with an end cap integrated radiator, a method for manufacturing / using such an electric machine, and a vehicle equipped with such an electric machine are presented. The electric machine includes an outer housing, a stator assembly mounted to the housing, and a rotor assembly rotatably mounted adjacent to the stator assembly. The stator assembly includes one or more stator windings mounted to an annular stator core. The rotor assembly includes one or more electromagnetic rotor windings mounted to a cylindrical rotor core. A rotor power transfer circuit (PTC) is electrically connected to the rotor assembly to energize the rotor windings. The rotor shaft is attached to the rotor core to rotate in unison therewith. One or more heat pipes are mounted on an outer surface of the rotor shaft and protrude axially between the rotor PTC and the rotor core. Each heat pipe passively extracts and transfers thermal energy from the rotor PTC.

Description

Technical Field

[0001] The present disclosure relates generally to electric machines and more particularly to thermal management systems for regulating the operating temperature of a separately excited motor (SEM) assembly. Background Art

[0002] The motor vehicles currently produced, such as modern automobiles, are initially equipped with a powertrain that operates to propel the vehicle and power the vehicle's onboard electronics. For example, in automotive applications, the vehicle powertrain is typically represented by a prime mover that transmits drive torque to the vehicle's final drive system (e.g., differential, axle, corner module, wheels, etc.) through an automatic or manually shifted power transmission. Due to its easy availability, relatively light weight, and overall efficiency, automobiles have historically been powered by reciprocating piston internal combustion engine (ICE) assemblies. As some non-limiting examples, such engines include compression ignition (CI) diesel engines, spark ignition (SI) gasoline engines, two-stroke, four-stroke, and six-stroke architectures, and rotary engines. On the other hand, hybrid electric and all-electric vehicles (collectively referred to as "electric vehicles") utilize alternative power sources to propel the vehicle, thereby minimizing or eliminating reliance on the traction power of fossil fuel-based engines.

[0003] A full electric vehicle (FEV) (colloquially referred to as an "electric vehicle") is an electrically driven vehicle configuration that completely omits the internal combustion engine and accompanying peripheral components of the powertrain, instead relying on a rechargeable energy storage system (RESS) and traction motors for vehicle propulsion. In a battery-based FEV, the engine components, fuel supply system, and exhaust system of an ICE-based vehicle are replaced with a single or multiple traction motors, rechargeable battery cells, and battery cooling and charging hardware. In contrast, a hybrid electric vehicle (HEV) powertrain employs a variety of traction power sources to propel the vehicle, most commonly operating an internal combustion engine component in conjunction with a battery-powered or fuel cell-powered traction motor. Because a hybrid electric drive vehicle is able to derive its power from a source other than the engine, the HEV engine can be fully or partially shut down when the vehicle is propelled by the electric motor. Summary of the invention

[0004] Traction motors are electric machines that convert electrical energy into rotational mechanical energy to propel a vehicle, such as FEV and HEV type cars. Many traction motors include a fixedly mounted stator carrying multi-phase electromagnetic windings, such as copper hairpin or I-pin bars, and a rotatable rotor carrying a designed pattern of magnets, such as core mounted permanent magnets (PMs) or electromagnetic armature windings, such as core mounted copper coils. Traction motors can be classified as alternating current (AC) or direct current (DC), brushed or brushless, rotary or linear, radial flux or axial flux. In radial flux internal rotor designs, the rotor can be coaxially nested inside the stator, while axial flux rotary designs can juxtapose the rotor and stator as face-to-face coaxial plates. Rotational excitation of the rotor assembly can be achieved by passing current through the multi-phase AC stator windings to generate a magnetic field; the magnetic field emitted by the stator interacts with the mating magnetic field generated by the permanent magnets or DC armature coils carried by the rotor.

[0005] The rotor assembly for many modern traction motors includes a rotor core made of thin ferrite disks that are stacked and laminated together to form a cylindrical body. Each rotor disk has a plurality of openings that, when aligned with the openings of an adjacent disk, form rotor slots that extend axially through the length of the rotor core. Permanent or electrically excited magnetic elements (such as PM bars or copper coils) are inserted into these rotor slots and secured to the rotor core. Unlike permanent magnet motor structures in which the rotor assembly carries internal or surface mounted magnets, a separately excited motor (SEM) is typically represented by an armature winding carried by the rotor that electromagnetically cooperates with a field winding carried by the stator to convert electrical energy into mechanical energy. The rotor core can be mounted to a motor shaft for outputting a propulsion generating motor torque generated by the motor or for inputting a power generating regenerative torque received by the motor.

[0006] During operation of a traction motor, significant amounts of heat may be generated by the internal electrical and electromagnetic hardware, for example due to windage, friction, and hysteresis losses. An integrated motor cooling system may be employed to prevent unwanted overheating conditions within the motor. For example, an active thermal management (ATM) system employs a central controller or dedicated control module to regulate the operation of a cooling circuit that circulates a coolant fluid through the motor components that generate heat. For an indirect liquid cooling system, a heat transfer coolant is circulated through a network of internal passages and tubes within the motor housing. In contrast, a direct liquid cooling system or "liquid immersion cooling" (LIC) sprays, sprays, or immerses the components of the motor in a direct conduction dielectric liquid coolant.

[0007] This article proposes a motor having a rotor shaft mounted heat pipe and / or vapor chamber thermally coupled to an end cover integrated heat sink, a method for manufacturing such a motor, and a method for operating such a motor, as well as a vehicle equipped with such a motor. By way of non-limiting example, a novel separately excited motor design extracts heat from a rotor power transfer circuit (PTC) by fixing a heat pipe and / or vapor chamber to the rotor shaft. The extracted heat can be axially transmitted from the PTC package toward the longitudinal end of the rotor core and transferred to the larger thermal body of the rotor end cover. The rotor end cover can be manufactured with fins that dissipate the transferred heat into the internal coolant volume of the drive unit (DU) housing. Jet or spray cooling can be used to extract heat from the pin fins and simultaneously transfer the thermal energy to the outside of the DU housing. The circular array of circumferentially spaced heat pipes / vapor chambers can be partially embedded in a polymer coating on the outer diameter (OD) surface of the rotor shaft. Axially protruding pin fins can be integrally formed on the axial face of the rotor end cover to convect heat to the DU housing volume. End cap spray cooling and / or sprinkler cooling may be employed to accelerate end cap thermal conductivity and thereby facilitate heat extraction from the PTC component.

[0008] Ancillary benefits of at least some of the disclosed concepts include a SEM architecture with reduced operating temperatures (e.g., at worst case operating point (WCOP)), which results in enhanced motor efficiency and extended motor performance limits (i.e., beyond comparable IPM designs). Unlike complex shaft-fed ATM cooling designs (which significantly increase the cost, complexity, and failure points of the system), the disclosed SEM design uses sealed heat pipes / vapor chambers and end cap heat sinks to quickly and efficiently extract heat from selected motor components. Other ancillary advantages may include that the SEM system eliminates the need for rare earth (RE) and heavy rare earth (HRE) materials, which may be susceptible to volatile price fluctuations and commodity shortages. Unlike many conventional SEM solutions that choose to operate at lower peak currents and limit peak operating speeds to reduce motor temperatures, the disclosed SEM system uses both active and passive cooling features to extract heat, thereby extending the SEM peak performance limits.

[0009] Various aspects of the present disclosure relate to a steam chamber and / or heat pipe mounted on a rotor shaft of an electrical PTC package for cooling an electric machine such as a motor, a generator, a transformer, an inductor, a dynamometer, a converter, etc. In an example, a motor includes a protective outer housing, a stator assembly fixedly attached to the housing, and a rotor assembly rotatably attached to the housing adjacent to the stator assembly. The stator assembly includes a stator core having at least one stator slot and at least one electromagnetic stator winding installed in the stator slot. Similarly, the rotor assembly includes a rotor core having at least one rotor slot and at least one electromagnetic rotor winding installed in the rotor slot. The rotor power transmission circuit is attached to the motor housing, for example, axially spaced from the rotor core and encapsulated in a separate PTC compartment. The PTC is electrically connected to the rotor assembly, for example, via a rotor shaft, to energize the rotor winding via a DC power feed. The rotor shaft is fixedly attached to the rotor core, for example, via a key, a spline, or a hub, to rotate in unison with the core. At least one heat pipe is mounted to the outer surface of the rotor shaft and protrudes axially along the shaft between the rotor PTC and the rotor core. Each heat pipe passively extracts thermal energy from the rotor PTC and transfers the extracted thermal energy to the outside of the rotor PTC.

[0010] Additional aspects of the present disclosure relate to an electric drive vehicle propelled by a SEM-type traction motor cooled by a rotor shaft mounted vapor chamber and / or heat pipe. As used herein, the terms "vehicle" and "motor vehicle" may be used interchangeably and synonymously to refer to any relevant vehicle platform, such as passenger vehicles (ICE, HEV, FEV, fuel cell, fully and partially autonomous, etc.), commercial vehicles, industrial vehicles, tracked vehicles, off-road and all-terrain vehicles, motorcycles, agricultural equipment, boats, aircraft, electric bicycles, etc. In an example, the motor vehicle includes a body with a passenger compartment, a plurality of wheels mounted to the body (e.g., via corner modules connected to a unibody or body-on-frame chassis), and other standard original equipment. For electric drive vehicle applications, the vehicle is equipped with a rechargeable energy storage system (RESS) (e.g., a traction battery pack) that powers the electrified powertrain. The powertrain employs one or more SEM-type traction motor / generator units (MGUs) that operate alone (e.g., for a FEV powertrain) or in conjunction with an internal combustion engine assembly (e.g., for a HEV powertrain) to drive one or more wheels to propel the vehicle.

[0011] Continuing the previous discussion, the traction motor includes a protective and insulating motor housing, a stator assembly rigidly mounted inside the motor housing, and a rotor assembly rotatably mounted inside the motor housing adjacent to the stator assembly. The stator assembly includes an annular stator core having a series of circumferentially spaced stator slots, and a plurality of electromagnetic stator windings (e.g., copper hairpin winding bars) are mounted in the stator slots. In contrast, the rotor assembly includes a cylindrical rotor core, which is nested inside the annular stator core and surrounded by the annular stator core. The rotor core has a series of circumferentially spaced rotor slots, and a plurality of electromagnetic rotor windings (e.g., copper winding coils) are mounted in the rotor slots. The rotor PTC is mounted inside the motor housing, for example, axially spaced from the rotor core and surrounding the rotor shaft. The rotor PTC is electrically connected to the rotor assembly to selectively energize the rotor windings. The rotor shaft is surrounded by the rotor core and attached to the rotor core to rotate in unison with it. A plurality of heat pipes are mounted on the outer diameter surface of the rotor shaft and circumferentially spaced around the rotor shaft. Each heat pipe passively extracts thermal energy from the rotor PTC and transfers the extracted thermal energy to the outside of the rotor PTC.

[0012] Aspects of the present disclosure also relate to manufacturing workflow processes, computer-readable media, and control logic for manufacturing or using any disclosed PTC cooling system, motor, and / or motor vehicle. In an example, a method for assembling a motor is proposed. The representative method includes, in any order and in any combination with any of the options and features disclosed above and below: receiving a housing of a motor; attaching a stator assembly to the housing, the stator assembly including a stator core and an electromagnetic stator winding mounted to the stator core; attaching a rotor assembly to the housing so that the rotor assembly is adjacent to the stator assembly and can rotate relative to the stator assembly, the rotor assembly including a rotor core and an electromagnetic rotor winding mounted to the rotor core; attaching a rotor power transmission circuit to the housing so that the rotor PTC is axially spaced from the rotor core and electrically connected to the rotor assembly to energize the rotor winding; attaching a rotor shaft to the rotor core to rotate in unison with it; and mounting a heat pipe on the outer surface of the rotor shaft so that the heat pipe protrudes axially between the rotor PTC and the rotor core, and the heat pipe is configured to passively extract heat energy from the rotor PTC and transfer the heat energy to the outside of the rotor PTC.

[0013] For any disclosed vehicle, method and motor, the integrated thermal management system may employ a single heat pipe or a plurality of heat pipes mounted on the outer surface of the shaft and spaced circumferentially around the rotor shaft. Each heat pipe may be flush against the outer surface of the shaft and may be substantially parallel to the rotor shaft. It is also conceivable that the rotor shaft is manufactured with axially elongated, surface-concave grooves in which the heat pipes may be placed. Alternatively, the entire heat pipe may be radially spaced from the rotor shaft, or alternatively, one end of the heat pipe may be radially spaced from the rotor shaft and the other end of the heat pipe may be pressed against the rotor shaft. The heat pipes may be parallel to each other and to the rotor shaft, and if desired, may be equally spaced from each other around the rotor shaft. One or more of all the heat pipes may be replaced with a flat or arcuate vapor chamber.

[0014] For any of the disclosed vehicles, methods, and motors, the outer surface of the rotor shaft may be covered in whole or in part with a polymer surface coating. It may be desirable that the surface coating be formed of an electrically insulating thermoplastic polymer as a single-piece, unitary structure. In this case, each heat pipe is at least partially embedded in the polymer surface coating. In order to enhance the thermal coupling of the PTC to the pipe, a thermal interface material (TIM) may be inserted between the heat pipe and the rotor PTC and adjacent to the heat pipe and the rotor PTC. The TIM layer electrically insulates the electrical PTC component from the heat pipe. The rotor PTC includes a plurality of electrical components surrounding the rotor shaft. In this case, the heat pipe may extend through one or more central cavities of the electrical components of the PTC and be thermally coupled to one or more of the electrical components of the PTC. For a contact-based rotor PTC, the PTC component may include a pair of (first and second) brushes coupled to a pair of (first and second) slip rings, respectively; in this case, the heat pipe may contact the slip rings. For a non-contact-based PTC, the components may include a rectifier, a rectifier printed circuit board (PCB), an electromagnetic coupler, a matching capacitor plate, and the like.

[0015] For any of the disclosed vehicles, methods, and motors, each heat pipe may include a sealed thermally conductive can (e.g., a copper or aluminum tube) containing a working fluid (e.g., water, acetone, methanol, or ammonia). The working fluid undergoes a phase change between liquid and gas, thereby extracting heat from the rotor PTC and transferring the extracted heat through one or both axial ends of the PTC package. A wick structure (e.g., a grooved, sintered, or mesh-type wick) is located inside the heat pipe can, adjacent to and, if necessary, covering the inner surface of the can. The wick structure transfers the liquid-phase working fluid to the proximal (first) axial end of the can, for example, via capillary action. An elongated vapor channel may extend longitudinally through the center of the wick structure. When the working fluid evaporates into a gas, the vapor channel transfers the working fluid to the distal (second) axial end of the sealed can; when the working fluid condenses into a liquid, the vapor channel transfers the fluid to the wick structure.

[0016] For any of the disclosed vehicles, methods, and electric machines, a left (first) rotor end cap may be attached to one axial end of the rotor core, and a right (second) rotor end cap may be attached to the opposite axial end of the rotor core. The rotor end cap may be adjacent to the longitudinal end of the heat pipe to receive therefrom thermal energy extracted from the rotor PTC. The rotor end cap may be an annular plate-like structure comprising one or more heat pipe cavities, each heat pipe cavity being recessed into the inner diameter radial surface of the rotor end cap and nesting the longitudinal end of the heat pipe therein. The rotor end cap may be manufactured with a set of end cap fins protruding axially away from the rotor core; these end cap fins dissipate the extracted thermal energy transferred to the outside of the rotor PTC and received by the rotor end cap. An optional active thermal management system may spray or inject a dielectric coolant fluid onto the end cap fins and, if necessary, pump the heated coolant fluid away from the rotor assembly.

[0017] Solution 1. A motor, comprising:

[0018] case;

[0019] a stator assembly including a stator core attached to the housing and an electromagnetic stator winding mounted to the stator core;

[0020] a rotor assembly including a rotor core rotatably attached to the housing adjacent the stator assembly and an electromagnetic rotor winding mounted to the rotor core;

[0021] a rotor power transfer circuit (PTC) attached to the housing, axially spaced from the rotor core and electrically connected to the rotor assembly to energize the rotor windings;

[0022] a rotor shaft attached to the rotor core for rotation in unison therewith; and

[0023] A heat pipe is mounted on the outer surface of the rotor shaft and protrudes axially between the rotor PTC and the rotor core, wherein the heat pipe is configured to passively extract heat energy from the rotor PTC and transfer the heat energy to outside the rotor PTC.

[0024] Option 2. An electric machine according to Option 1, wherein the heat pipe includes a plurality of heat pipes mounted on the outer surface and spaced circumferentially around the rotor shaft.

[0025] Option 3. The electric machine according to Option 2, wherein the heat pipe is adjacent to the outer surface and parallel to the rotor axis.

[0026] Option 4. The electric machine according to Option 2, wherein the heat pipes are parallel to each other and are equidistant from each other.

[0027] Option 5. An electric machine according to Option 2, wherein the outer surface of the rotor shaft includes a polymer surface coating, and wherein the heat pipe is at least partially embedded in the polymer surface coating.

[0028] Embodiment 6. The electric machine according to Embodiment 2 further includes a thermal interface material (TIM) interposed between the heat pipe and the rotor PTC and electrically insulating the heat pipe and the rotor PTC.

[0029] Embodiment 7. The electric machine according to embodiment 2, wherein the rotor PTC comprises a plurality of electrical PTC components surrounding the rotor shaft, and wherein the heat pipe extends through a central cavity of the electrical PTC component and is thermally coupled to the electrical PTC component.

[0030] Embodiment 8. The electric machine according to embodiment 7, wherein the electrical PTC component comprises first and second brushes coupled to first and second slip rings, and wherein the heat pipe contacts the first and second slip rings.

[0031] Option 9. An electric machine according to Option 1, wherein the heat pipe includes a sealed tank that contains a working fluid, and the working fluid is configured to undergo a phase change between a liquid phase and a gas phase, thereby extracting thermal energy from the rotor PTC and transferring the thermal energy through an axial end of the rotor PTC.

[0032] Option 10. An electric machine according to Option 9, wherein the heat pipe further comprises a wick structure, which is located inside the sealed can and is configured to transfer the working fluid from the first axial end to the second axial end of the sealed can when in a liquid phase.

[0033] Solution 11. The electric machine according to Solution 1 further includes a rotor end cover attached to an axial end of the rotor core and adjacent to a longitudinal end of the heat pipe to receive therefrom the extracted heat energy transferred to the outside of the rotor PTC.

[0034] Embodiment 12. The electric machine according to embodiment 11, wherein the longitudinal ends of the heat pipes are radially inserted between the rotor end cover and the rotor shaft.

[0035] Embodiment 13. The electric machine according to embodiment 11, wherein the rotor end cap includes a plurality of end cap fins, the end cap fins protruding axially away from the rotor core and configured to dissipate extracted heat energy transferred out of the rotor PTC and received by the rotor end cap.

[0036] Solution 14. A motor vehicle, comprising:

[0037] Car body;

[0038] a plurality of wheels attached to the vehicle body;

[0039] a rechargeable energy storage system (RESS) attached to the vehicle body; and

[0040] a traction motor attached to the vehicle body, electrically connected to the RESS, and configured to drive one or more of the wheels to propel the motor vehicle, the traction motor comprising:

[0041] Motor housing;

[0042] a stator assembly rigidly mounted inside the motor housing, the stator assembly comprising an annular stator core and a plurality of electromagnetic stator windings mounted within circumferentially spaced stator slots of the stator core;

[0043] a rotor assembly rotatably mounted within the motor housing adjacent the stator assembly, the rotor assembly comprising a cylindrical rotor core nested within an annular stator core and a plurality of electromagnetic rotor windings mounted within circumferentially spaced rotor slots of the rotor core;

[0044] a rotor power transfer circuit (PTC) mounted inside the motor housing, axially spaced from the rotor core, and electrically connected to the rotor assembly to selectively energize the rotor windings;

[0045] a rotor shaft surrounded by and attached to the rotor core for rotation in unison therewith; and

[0046] A plurality of heat pipes are mounted on an outer diameter (OD) surface of the rotor shaft and spaced circumferentially about the rotor shaft, each heat pipe being configured to passively extract thermal energy from the rotor PTC and transfer the thermal energy to an exterior of the rotor PTC.

[0047] Solution 15. A method for assembling an electric machine, the method comprising:

[0048] a housing for receiving the motor;

[0049] attaching a stator assembly to the housing, the stator assembly comprising a stator core and electromagnetic stator windings mounted to the stator core;

[0050] attaching a rotor assembly to the housing such that the rotor assembly is adjacent to and rotatable relative to the stator assembly, the rotor assembly including a rotor core and an electromagnetic rotor winding mounted to the rotor core;

[0051] attaching a rotor power transfer circuit (PTC) to the housing such that the rotor PTC is axially spaced from the rotor core and electrically connected to the rotor assembly to energize the rotor windings;

[0052] attaching a rotor shaft to the rotor core for rotation in unison therewith; and

[0053] A heat pipe is mounted on the outer surface of the rotor shaft such that the heat pipe protrudes axially between the rotor PTC and the rotor core, the heat pipe being configured to passively extract thermal energy from the rotor PTC and transfer the thermal energy to outside the rotor PTC.

[0054] Option 16. A method according to Option 15, wherein the heat pipe includes a plurality of heat pipes mounted on the outer surface and spaced circumferentially around the rotor shaft.

[0055] Option 17. The method of Option 16, wherein the heat pipe is adjacent to the outer surface and parallel to the rotor axis.

[0056] Option 18. The method according to Option 16, wherein the heat pipes are parallel to each other and are equidistantly spaced from each other.

[0057] Option 19. A method according to Option 16, wherein the outer surface of the rotor shaft includes a polymer surface coating, and wherein the heat pipe is at least partially embedded in the polymer surface coating.

[0058] Embodiment 20. The method of embodiment 16, wherein the rotor PTC comprises a plurality of electrical PTC components surrounding the rotor shaft, and wherein the heat pipe extends through a central cavity of the electrical PTC component and is thermally coupled to the electrical PTC component.

[0059] The above summary of the invention does not represent every embodiment or every aspect of the present disclosure. On the contrary, the foregoing summary of the invention only provides an overview of some novel concepts and features set forth herein. When combined with the accompanying drawings and the appended claims, the above-mentioned features and advantages of the present disclosure and other features and attendant advantages will be readily apparent from the following detailed description of the illustrated examples and representative modes for implementing the present disclosure. In addition, the present disclosure expressly includes any and all combinations and sub-combinations of the elements and features set forth above and below. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a partially schematic side view of a representative motor vehicle having a rechargeable traction battery pack, a high voltage electrical system, and a SEM-based electrified powertrain that may be used to practice aspects of the present disclosure.

[0061] Figure 2 is a schematic single-line diagram illustrating a representative SEM drive system that can be used to practice aspects of the present disclosure.

[0062] Figure 3 is a cross-sectional side view of a representative electric machine with a rotor shaft mounted heat pipe and end cap integrated heat sink for removing heat from a contact-type (brush-type) rotor PTC in accordance with aspects of the present disclosure.

[0063] Figure 4 is a cross-sectional side view of another representative electric machine having a rotor shaft mounted heat pipe and end cap integrated heat sink for removing heat from a non-contact type (induction) rotor PTC in accordance with aspects of the present disclosure.

[0064] Figure 5is a cross-sectional side view of yet another representative electric machine having a rotor shaft mounted heat pipe and end cap integrated heat sink for removing heat from another non-contact type (capacitor) rotor PTC in accordance with aspects of the present disclosure.

[0065] The present disclosure is susceptible to various modifications and alternative forms, some representative embodiments of the present disclosure are shown by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the accompanying drawings listed above. On the contrary, the present disclosure covers all modifications, equivalents, combinations, arrangements, groupings, and alternatives that fall within the scope of the present disclosure, such as those covered by the appended claims. DETAILED DESCRIPTION

[0066] The present disclosure is susceptible to embodiments in many different forms. Representative embodiments of the present disclosure are shown in the drawings and will be described in detail herein, it being understood that these embodiments are provided as illustrations of the disclosed principles, rather than limitations on the broad aspects of the present disclosure. To this end, elements and limitations such as those described in the abstract, background technology, summary of the invention, illustrations, and detailed description of the embodiments, but not explicitly set forth in the claims, should not be incorporated into the claims individually or collectively by implication, inference, or otherwise. In addition, the expressions "first", "second", "third", etc. in the specification or claims are not themselves used to establish an order or numerical limitation; unless otherwise specifically stated, these names may be used to facilitate reference to similar features in the specification and drawings and to divide between similar elements in the claims.

[0067] For the purposes of this detailed description, unless otherwise stated: the singular includes the plural and vice versa; the words "and" and "or" shall be both conjunctions and transitional conjunctions; the words "any" and "all" shall each mean "any and all"; and the words "including," "containing," "comprising," "having," and the like shall each mean "including but not limited to." In addition, approximate words, such as "about," "almost," "substantially," "roughly," "approximately," and the like, may each be used herein to mean, for example, "at, close to, or nearly at," or "within 0-5% of," or "within an acceptable manufacturing tolerance," or any logical combination thereof. Finally, directional adjectives and adverbs, such as front, rear, inside, outside, right, left, vertical, horizontal, upward, downward, front, rear, left, right, and the like, may be relative to a motor vehicle, such as the forward direction of travel of a motor vehicle when the vehicle is operatively oriented on a level running surface.

[0068] Referring now to the drawings, wherein like reference numerals represent like features throughout the several views, Figure 1A representative motor vehicle is shown, generally indicated at 10, and is depicted herein as a sedan-style electric drive vehicle for discussion purposes. The illustrated vehicle 10 (also referred to herein as a "motor vehicle" or simply "vehicle") is merely an exemplary application that can be used to practice various aspects of the present disclosure. Likewise, incorporating the present concept into a FEV power system powered by a single set of RESS and a single SEM traction motor should be understood as a non-limiting implementation of the disclosed features. Thus, it will be understood that various aspects and features of the present disclosure can be applied to other power system architectures, incorporated into any logically related type of motor vehicle, and equally used in both automotive and non-automotive applications. In addition, only selected components of the motor vehicle, SEM drive, and HV electrical system are shown and described herein with additional detail. However, the vehicle, SEM, and electrical system discussed below may include many additional and alternative features and other available peripheral components to perform the various methods and functions of the present disclosure.

[0069] Figure 1 The representative vehicle 10 is initially equipped with a central console telecommunications and information ("telematics") unit 14 that interfaces with a remotely located cloud computing host service 24 (e.g., ) for wireless communication (e.g., via cellular towers, satellite services, etc.). As a non-limiting example, Figure 1 Other in-vehicle hardware components 16 shown in the figure include an electronic video display device 18, a microphone 28, an audio speaker 30, and various user input controls 32 (e.g., buttons, knobs, switches, touch screens, etc.). These hardware components 16 serve as a human / machine interface (HMI) that enables a user to communicate with the telematics unit 14 and other components that reside both to the vehicle 10 and remote from the vehicle 10. The microphone 28, for example, provides a means for the occupant to input verbal commands. In contrast, the speaker 30 provides auditory output to the vehicle occupants and can be a separate speaker dedicated to the telematics unit 14, or can be part of the audio system 22. The audio system 22 is operatively connected to the network connection interface 34 and the audio bus 20 to receive analog information and present it as sound via one or more speaker components.

[0070] The network connection interface 34 is communicatively coupled to the telematics unit 14, suitable examples of which include twisted pair / fiber optic Ethernet switches, parallel / serial communication buses, local area networks (LAN) interfaces, controller area networks (CAN) interfaces, etc. The network connection interface 34 enables the vehicle hardware 16 to send and receive signals between each other and with systems and subsystems both onboard the vehicle body 12 and off-board the vehicle body 12. This allows the vehicle 10 to perform various vehicle functions, such as regulating powertrain output, activating the vehicle braking system, controlling vehicle steering, regulating the charging and discharging of the vehicle battery, and other automatic functions. For example, the telematics unit 14 receives signals from and transmits signals to the following modules: powertrain control module (PCM) 52, onboard charging module (OBCM) 54, electronic battery control module (EBCM) 56, steering control module (SCM) 58, brake system control module (BSCM) 60, and various other vehicle ECUs.

[0071] Continue to refer Figure 1 , the telematics unit 14 is an onboard computing device that provides a mix of services both alone and through its communications with other networked devices. The telematics unit 14 is generally comprised of one or more processors 40, each of which may be implemented as a discrete microprocessor, an application specific integrated circuit (ASIC), or a dedicated control module. The vehicle 10 may provide centralized vehicle control via a central processing unit (CPU) 36, which is operatively coupled to an IC real time clock (RTC) 42 and one or more electronic memory devices 38, each of which may take the form of a CD-ROM, solid state drive (SSD) memory, hard disk drive (HDD) memory, semiconductor memory, or the like.

[0072] Long range vehicle communication (LRC) capabilities with off-board devices may be provided via a cellular communication component, a navigation and positioning component (e.g., a global positioning system (GPS) transceiver), or a wireless modem (all generally indicated as 44). Short range communications (SRC) may be provided via a short range wireless communication device 46 (e.g., Unit), dedicated short range communication (DSRC) component 48 and / or dual antenna 50. It should be understood that the vehicle 10 may be implemented without one or more of the components listed above, or alternatively, may include additional components and functions required for a specific end use. The above communication devices can provide data exchange as part of a periodic broadcast in a vehicle-to-vehicle (V2V) communication system or a vehicle-to-everything (V2X) communication system.

[0073] The CPU 36 receives sensor data from one or more sensing devices that use, for example, light detection, radar, laser, ultrasound, optics, infrared, or other suitable technologies to perform automatic vehicle operation or vehicle navigation services, including short-range communication technologies (e.g., DSRC) or ultra-wideband (UWB) radio technologies. According to the illustrated example, the automobile 10 may be equipped with one or more digital cameras 62, one or more range sensors 64, one or more vehicle speed sensors 66, one or more vehicle dynamic sensors 68, and any required filtering, classification, fusion, and analysis hardware and software for processing the raw sensor data. The type, arrangement, quantity, and interoperability of the distributed array of onboard sensors may be adjusted individually or collectively for a given vehicle platform to achieve a desired level of autonomous vehicle operation.

[0074] To propel the motor vehicle 10, the electrified powertrain is operable to generate and transmit tractive torque to one or more of the vehicle's drive wheels 26. Figure 1 , represented by an electric traction motor 78 connected to a rechargeable energy storage system (RESS), which can essentially be a chassis mounted traction battery pack 70. The battery pack 70 may include one or more battery modules 72, each having a set of electrochemical battery cells 74, such as lithium-ion or lithium-polymer battery cells of the pouch, can or prismatic type. One or more electric machines, such as adjustable speed multiphase SEM motor / generator (M) units 78, draw electrical power from one or more rechargeable battery cells (e.g., traction battery pack 70) and, optionally, deliver electrical power to one or more rechargeable battery cells (e.g., traction battery pack 70). The HV electrical system having a power inverter module (PIM) 80 electrically connects the battery pack 70 to the motor / generator unit 78 and regulates the current transfer between them. The battery pack 70 can be configured so that module management, unit sensing, and module-to-host communication functions are directly integrated into each module 72 and performed wirelessly via a wirelessly enabled unit monitoring unit (CMU) 76.

[0075] Next turn Figure 2 , shows a non-limiting example of a SEM drive system 200 that may be adapted to electrically connect and disconnect a rechargeable battery assembly 202 to a high voltage electrical power source, such as an AC power utility grid 201. Although different in appearance, it is contemplated that the present invention may be referred to herein as Figure 1 The traction motor and Figure 3-5 Any features and options described for the motor may be incorporated individually or in any combination Figure 2 Although not limited in itself, Figure 2The SEM drive system 200 may be represented by a rechargeable battery assembly 202 , a power factor correction (PFC) device 204 , a traction inverter module (TIM) device 206 , a power transfer circuit (PTC) device 208 , and a separately excited motor (SEM) unit 210 .

[0076] The rechargeable battery assembly 202 may employ any of the battery options described herein, including one or more battery packs or one or more battery modules, each battery module containing one or more rechargeable battery cells 212 (e.g., liquid, polymer, or solid state cell configurations in prismatic, pouch, or cylindrical cell form factors). In addition, each battery assembly 202 may include a set of solid state relay contactors / switches (not shown) that independently respond to signals from a suitable controller / control module (e.g., EBCM) to manage the electrical output of the battery system. Although for simplicity of illustration, the Figure 2 Only one battery assembly 202 and one motor 210 are shown, but the SEM drive system 200 may include any number of battery units, motor units, and associated electrical hardware without departing from the intended scope of the present disclosure.

[0077] The DC-AC and AC-DC power inverter 206 (which may be part of a traction inverter module (TIM)) is connected to the SEM unit 210 via multi-phase windings 214A, 214B, and 214C to transfer power between the SEM 210 and the battery assembly 202. Figure 2 2, the TIM device 206 (also referred to as an "inverter stage" or "inverter sub-circuit") is directly electrically connected to and interposed between the PFC device 204 and the SEM unit 210. In the illustrated example, the TIM device 206 lacks a direct electrical connection to the rotor assembly 218 of the SEM unit 210. The DC battery output voltage is transferred from the battery 202 to the TIM 206 and PTC 208 across the positive and negative voltage bus rails 220A and 220B using optional fixed-type DC bus capacitors 222 (placed across the rails 220A, 220B).

[0078] A representative power inverter topology may incorporate multiple inverters and corresponding motor control modules operable to receive motor control commands and control inverter states therefrom for providing motor drive or regeneration functionality. Figure 2 The TIM device 206 may include one or more pairs of series-connected electromechanical or semiconductor switches that cooperatively convert DC power from one or more energy storage devices (e.g., battery assembly 202) into AC voltage for powering one or more motors (e.g., SEM unit 210) via high-frequency switching. According to the illustrated example, the TIM device 206 includes six semiconductor switches SI1 , S I2 , S I3 , S I4 , S I5 and S I6 , which are arranged into three pairs 224A, 224B and 224C of solid-state TIM switches connected in series. The three switch pairs 224A, 224B and 224C can be electrically connected in parallel with each other. Each switch S I1 -S I6 A voltage-controlled bipolar switch device that can be implemented as an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET), a wideband gallium nitride (GaN) device (WBG), or other suitable switch form having a corresponding gate, to which a gate signal is applied to change the on / off state of the switch.

[0079] Each pair of solid-state TIM switches 224A, 224B, and 224C may be electrically connected in series to a respective one of the field windings 214A, 214B, 214C carried by the stator of the SEM stator assembly 216. A power inverter, such as Figure 2 The TIM device 206 may use a fast controller to automatically switch control techniques, such as a pulse width modulation (PWM) signal, to convert the DC power supplied during the discharge of the battery cell 202 into AC power suitable for driving the SEM unit 210. A pre-charge circuit (not shown) may be used to charge the DC link capacitor 226 within the TIM device 206 at a controlled rate to equalize the voltage across each pair of switches 224A-224C before closing the contactors / switches within the battery cell 202.

[0080] The multi-stage PFC device 204 is selectively electrically connected to the electrical power source 201 and, once connected, is interposed between the power source 201 and the rest of the SEM drive system 200 (i.e., the battery unit 202, the TIM 206, the PTC 208, and the SEM 210). The PFC device 204 (also referred to as a "PFC stage" or a "PFC converter") provides power factor correction by shaping the input current, for example, to meet the current harmonic limits of the system 200. Figure 2 In the embodiment, the PFC device 204 is directly electrically connected to the power source 201 and the TIM device 206 and is inserted between the power source 201 and the TIM device 206. The PFC device 204 can be located on the stator side of the SEM drive system 200, opposite to the battery unit 202. The PFC subcircuit can adopt a variety of different topologies, including single-phase and multi-phase PFC configurations, multi-level (2-level, 3-level...N-level) PFC configurations, active and hybrid switch PFC configurations, etc. Multi-phase PFC may be suitable for example Figure 2 The application shown in Figure 1, where the PFC is located on the stator side of the SEM, in line with the multi-phase windings of the motor.

[0081] The multi-stage PTC device 208 (also referred to as a “PTC stage” or “rotor PTC”) is electrically connected on its output side to the rotor side of the SEM unit 210 and on its input side to both the battery unit 202 and the PFC device 204 . Figure 2 The PTC device 208 can provide single-phase rotor excitation functionality for the rotor assembly 218 of the SEM, for example, to optimize motor control and system charging. Figure 2 2, the PTC device 208 is directly electrically connected to and interposed between the battery cell 202 and the SEM rotor assembly 218. In the illustrated example, the PTC device 208 lacks a direct electrical connection to the stator assembly 216 of the SEM unit 210.

[0082] A separately excited motor unit 210 is interposed between the TIM 206 and the PTC 208 and is powered by the rechargeable battery assembly 202 to generate a motor output torque, for example, to rotate Figure 1 26 to propel the vehicle 10 or perform work in non-automotive SEM drive applications. Unlike multi-phase PM electric motors that rely on permanent magnets carried by the rotor, synchronous wound field SEMs are typically represented by armature windings carried by the rotor that electromagnetically cooperate with field windings carried by the stator to convert electrical energy into mechanical energy. As shown, the SEM unit 210 includes a rotor assembly 218 that is coaxial with the stator assembly 216 and rotatable relative to the stator assembly 216. For radial flux, internal rotor designs, the stator assembly 216 includes an annular stator core 246 that carries a plurality of electromagnetic stator "field" windings 214A-214C. In contrast, the rotor assembly 218 includes a cylindrical rotor core 248 that carries one or more electromagnetic rotor "armature" windings 234. In this example, the rotor core 248 is rotatably mounted inside the hollow center of the stator core 246 so that the stator assembly 216 surrounds the rotor assembly 218.

[0083] The field windings 214A-214C and the armature winding 234 are excited using the electric power provided by the battery assembly 202; once excited, the field windings 214A-214C carried by the stator are electromagnetically coupled with the armature winding 234 carried by the rotor and drive the armature winding 234 carried by the rotor (the electromagnetic coupling is Figure 2 216 and the rotor 218). Figure 4) may be splined, keyed, bolted, or otherwise fixedly attached to the rotor core 248 to rotate in unison therewith and output motor torque therefrom. Although not limiting per se, the stator and rotor cores 246, 248 may be manufactured as laminated core structures, each of which is composed of a stack of iron or other iron-containing plates. Although illustrated and described as a radial flux motor, the SEM unit 210 may employ axial flux and transverse flux architectures within the scope of the present disclosure.

[0084] Separately excited (induction) motors are not only an excellent replacement for many interior permanent magnet (IPM) motors in terms of performance and efficiency, SEMs also eliminate the cost and relatively short expected operating life of rare earth (RE) and heavy rare earth (HRE) magnets. However, the additional power electronics used to excite the armature windings of the SEM unit generate heat that needs to be mitigated to ensure that the SEM can function most efficiently at all operating points. To help regulate the operating temperature of the separately excited motor, the disclosed thermal management system uses rotor shaft mounted heat pipes and / or vapor chambers to extract and discharge heat from the rotor power transmission circuit while the PTC feeds DC power to the rotor windings. The heat pipe / vapor chamber can be packaged for direct (contact) or indirect (non-contact) heat extraction to efficiently and effectively cool the SEM. Once extracted, the heat pipe / vapor chamber can transfer the heat generated by the PTC outside the power electronics package and transfer the extracted heat to a larger thermal mass for dissipation. For contact-based power transmission circuits, heat can be extracted from brushes and slip rings; for non-contact-based power transmission circuits, heat can be extracted from rectifier power electronics and rotating capacitor plates.

[0085] To reduce the cost, complexity, and warranty issues associated with typical active thermal management of rotor PTCs (e.g., slot cooling or jet impingement), the disclosed passive thermal management system employs an axial heat pipe / vapor chamber rigidly mounted to the outer diameter surface of the rotor shaft to extract heat from the electrical components of the PTC (e.g., slip rings and brushes). The heat pipe / vapor chamber is a self-contained heat sink device that does not use rotating seals, glycol pumps, or other moving parts that may fail during system operation. In addition, the disclosed rotor shaft mounted heat pipe and vapor chamber are closed, passive thermal management devices that do not interact or interfere with the stator, thereby reducing system complexity while ensuring that the rotor operating speed, inertial mass, and structural integrity are maintained for high-speed operation.

[0086] Next turn Figure 3 , shows another example of an electric machine 310, which is represented as a radial flux, internal rotor type separately excited motor unit, which is cooled using a rotor shaft mounted heat pipe / vapor chamber, an end cover integrated heat sink and optional injection or spray ATM cooling. As described above, it is contemplated that reference Figure 1The traction motor 78 and Figure 2 Any features and options described for the SEM unit 210 may be incorporated individually or in any combination Figure 3 As some non-limiting similarities, Figure 3 The electric motor 310 is assembled using a protective and isolating outer housing 302 (e.g., a cast metal integrated electric drive unit (EDU) housing), which provides a mechanical interface for mounting to a system support structure (e.g., a body-on-frame or non-body-on-frame chassis). A multi-phase, field-wound, and AC-fed stator assembly 316 is rigidly mounted inside the housing 302, for example, via an axial clamping ring 308. Separated from the stator assembly 316 by an air gap is a single-phase, armature-wound, and DC-fed rotor assembly 318, which is rotatably mounted within the housing 302, for example, via a high-speed precision roller bearing 304. The rotor assembly 318 is securely mounted to a power transmission (motor or output) shaft 306, for example, via a key, spline, collar, hub, etc., to rotate in unison therewith. The shaft 306 is used to output torque generated by the electric motor 310 and / or receive input torque generated by an external source.

[0087] Similar to Figure 2 The stator assembly 216, Figure 3 The stator assembly 316 is constructed of a magnetic flux permeable stacked lamination annular stator core 320 having a plurality of circumferentially spaced stator slots 321 radially aligned with and extending axially through the stator core 320. A corresponding set of electromagnetic conductors 326 (also referred to herein as "stator windings" or "field windings") are wound through each axially elongated slot 321 of the stator core 320, which may be hairpins, I-pins, D-pins, or flat bar copper conductors in nature. Stator teeth separate the radially innermost ends of the slots 321, with the stator teeth pointing toward the outer diameter (OD) periphery of the rotor assembly 318. The stator teeth direct the magnetic flux generated by the stator windings 326 across the air gap to electromagnetically link with the electromagnets carried by the rotor assembly 318 before completing the magnetic flux path back to the stator assembly 316.

[0088] Similar to Figure 2 The rotor assembly 218, Figure 3The rotor assembly 318 is composed of a stacked lamination cylindrical rotor core 322 that is permeable to magnetic flux, and the rotor core 322 has a plurality of circumferentially spaced rotor slots 323 that are radially recessed into the rotor core 322 and extend axially through the rotor core 322. The rotor core 322 is nested inside and surrounded by the stator core 320 so that both cores 320, 322 are coaxial with the shaft 306. Electromagnetic conductors 328 (also referred to herein as "rotor windings" or "armature windings") are wound through the axially elongated rotor slots 323, which can be essentially solid wire or stranded copper coils composed of single-wire or multi-wire windings. Rotor teeth separate the radially outermost ends of the slots 323, and the rotor teeth point to the inner diameter (ID) periphery of the stator assembly 316. These rotor teeth guide the magnetic flux generated by the rotor windings 328 across the air gap to electromagnetically link with the electromagnets carried by the stator assembly 316.

[0089] Figure 3 The operation of the SEM 310 is affected in part by a magnetic field which is generated by the rotor assembly 318 upon receiving a magnetic field generated by a suitable electrical energy source (e.g. Figure 1 The DC current supplied by the traction battery pack 70 (e.g., for automotive applications) or the battery assembly 202 (e.g., for non-automotive applications) is generated. As the rotor assembly 318 rotates during operation of the motor 310, a DC power supply is provided to the rotor winding 328 through a rotating electromechanical interface (i.e., a rotor power transmission circuit 330). For a contact-type PTC configuration, the rotating interface can be represented by a pair of conductive (positive and negative) brushes 332A and 332B (the "fixed side" of the PTC), which are respectively matched with a pair of conductive (positive and negative) slip rings 334A and 334B (the "rotating side" of the PTC). The brushes 332A, 332B are rigidly fixed in a dedicated PTC ("dry area") compartment 312 of the housing 302 via a brush holder assembly 314. In contrast, the slip rings 334A, 334B are fixed to the OD surface of the rotor shaft 306 and extend circumferentially therearound, thereby being movably mounted in the PTC compartment 312. Each brush 332A, 332B is electrically coupled to a respective (positive and negative) electrical lead 336A, 336B and slides against a respective slip ring 334A, 334B, thereby transferring DC current from the electrical energy source to the rotor assembly 318 to energize the armature winding 328. A target position sensor 338, which may be a potentiometer, an inductive angle sensor, or a rotary encoder in nature, actively monitors the rotational position of the rotor shaft 306 and, therefore, the slip rings 334A, 334B.

[0090] In order to passively cool the motor 310, at least one heat pipe 340 is operably attached to the rotor shaft 306 to extract thermal energy from one or more heat generating electrical components of the rotor PTC 330. According to the illustrated example, the rotor shaft 306 is an elongated right circular cylinder that is made of a rigid metal or polymer material as a single-piece structure. A single heat pipe 340 or a group of heat pipes 340 can be mounted to the outer surface of the rotor shaft, protruding axially between the rotor PTC 330 and the rotor core 322. For high speed, high torque applications, multiple heat pipes 340 (e.g., four in the accompanying drawings) can be rigidly mounted to the OD surface of the shaft and spaced circumferentially around the rotor shaft 306. These heat pipes 340 can be substantially parallel to each other and to the rotor shaft 306. As shown in Figure 3 As can be best seen in the upper left illustration of FIG. 3 , the heat pipes 340 can be substantially equally spaced from each other around the rotor shaft 306 (e.g., approximately 90 degrees between adjacent heat pipes). When packaged in this manner, the heat pipes 340 rotate around the rotation axis A during rotation of the rotor shaft 306. R1 Move in unison.

[0091] The OD surface of the rotor shaft 306 may be covered in whole or in part with a polymer surface coating 358 to help prevent inadvertent shorting between the positive and negative slip rings 334A, 334B during energization of the rotor assembly 318 via the rotor PTC 330. To simplify design and manufacturing, the rotor shaft surface coating 358 may be formed as a single-piece, unitary structure from an electrically insulating thermoplastic polymer (e.g., an injection molded liquid crystal polymer (LCP) resin). In this case, each heat pipe 340 is at least partially embedded within the polymer surface coating 358, such that, for example, only a predetermined contact area of ​​the radially outermost surface of the heat pipe 340 is exposed through the coating 358. When packaged in this manner, the radially innermost surface of each individual heat pipe 340 may be flush against the OD surface of the rotor shaft 306. Alternatively, the coating-embedded heat pipe 340 may be radially spaced from the rotor shaft 306, or alternatively, the proximal (left) axial end of the heat pipe 340 may be radially spaced from the rotor shaft 306 and the opposite distal (right) axial end of the tube 340 may abut the shaft 306. To electrically insulate the rotor PTC 330 from the heat pipe 340, an optional thermal interface material (TIM), such as an acrylic polymer strip 364, may be interposed between each heat pipe 340 and the annular slip ring 334A, 334B. It is contemplated that, for example, if the heat pipe is made of or coated in a non-conductive material, the TIM strip 364 may be omitted from the SEM 310. In addition, the heat pipe 340 may also assist in cooling the polymer surface coating 358 of the rotor shaft 306.

[0092] The rotor PTC 330 contains a number of electrical components, such as Figure 3Rotating electromechanical slip rings 334A, 334B, which surround the rotor shaft 306 and are thermally coupled to heat pipes 340. These slip rings 334A, 334B electrically connect metal / graphite brushes 332A, 332B to the rotor winding 328, for example, via through-hole conduits or surface-etched leads (not shown). Each heat pipe 340 extends through the central cavity of the PTC slip rings 334A, 334B and is directly or indirectly thermally coupled to the PTC slip rings 334A, 334B. With this arrangement, the heat pipes 340 are substantially orthogonal to the slip rings 334A, 334B and extend axially from the slip rings 334A, 334B, protrude outward from the PTC compartment 312 and terminate near the axial end of the rotor core 322 (without contact).

[0093] Although depicted and described herein as using shaft mounted heat pipes, Figure 3 The motor 310 may also replace any or all of the heat pipes 340 with thermal energy dissipation vapor chambers. For example, a narrow width planar vapor chamber may replace each heat pipe 340; alternatively, a curved vapor chamber of expanded width may replace multiple heat pipes 340. As a further option, the shaft mounted heat pipes / vapor chambers described herein may be surface mounted devices (as shown), surface recessed devices (received in corresponding channels in the OD surface of the recessed shaft), or may be subsurface devices (located in internal rotor shaft slots). It is also contemplated that the SEM 310 assembly may include more or fewer heat pipes 340, and the heat pipes 340 may take alternative shapes, sizes, and packaging locations to the illustrated configuration.

[0094] Each heat pipe 340 protrudes axially from the terminal end of the rotor shaft 306 to the axial end of the rotor core 322 and simultaneously extracts heat energy generated by the mating PTC components to transfer the extracted heat energy out of the PTC compartment 312. In effect, the heat pipe 340 acts as a thermodynamic conduit that interfaces the heat generating components of the rotor PTC 330 with the convection cooling rotor end cap 350 and the conductive cooling dielectric fluid 352 that circulates through the internal coolant ("wet area") chamber of the housing 302. As shown in Figure 3 As best seen in the lower left illustration of FIG. , each heat pipe 340 can be constructed of a hermetically sealed and thermally conductive can 342 that can be manufactured as a rigid hollow tube formed of copper or aluminum. The heat pipe can 342 contains a working fluid (in Figure 3 344' and gas 344''), such as water, acetone, methanol, ammonia or a mixture of water and refrigerant, which converts thermal energy (heat) into mechanical energy (and vice versa) by undergoing a phase change between liquid 344' and gas 344''.

[0095] Working fluid 344 flows freely through three adjacent sections of tank 342: a heat absorbing "evaporation" section S at the proximal end of tank 342; 1ELocated at the center of the tank 342 and located at the evaporation portion S 1E The middle "insulation" part S of the terminal end side 2A and at the distal end of the tank 342 and at the "insulating" portion S 2A The heat removal "condensation" section S on the side of the terminal end 3C A fluid wicking structure 346 is enclosed within the tank 342, which draws the liquid working fluid 344' from the condensed portion S at the distal axial end of the tank 342, for example, via capillary action. 3C The evaporated portion S delivered to the proximal axial end of the tank 342 1E The wick structure 346 can take on numerous form factors, including fine fiber roving wicks, wound fabric wicks, intertwined wire wicks, mesh wicks, sintered powder wicks, etc. As shown, the wick structure 346 is pressed against the inner surface of the can 342 and substantially covers the inner surface of the can 342.

[0096] The elongated vapor channel 347 extends through the center of the heat pipe canister 342 and the wick structure 346, which allows the vapor phase working fluid 344" to evaporate from the evaporation portion S in the PTC compartment 312. 1E Passing through the heat insulating portion S extending along the rotor shaft 206 2A The condensed portion S transmitted to the adjacent rotor core 322 3C When the working fluid 344 cools and condenses into a liquid, the vapor channel 347 delivers the working fluid 344' to the wick structure 346. For ease of manufacturing and simplicity of design, it may be desirable that all axially mounted heat pipes 340 are substantially identical in structure to one another. In addition, each heat pipe 340 may be a fluid-tight discrete unit without a fluid port, such as for exchanging fluid with the internal coolant chamber 303 of the housing 302.

[0097] During operation of the motor 310, the electrical components of the rotor PTC 330 will generate frictional and resistive heat, especially during high speed operation (e.g., 10,000+RPM). A portion of this PTC generated heat will be transferred through the sealed can 342 to the wick structure 346 of the heat pipe 340. Specifically, the heat energy is conducted through the proximal end (evaporation portion S 1E ), causing a portion of the working fluid 344 sealed in the tank 342 to evaporate. When the working fluid 344 evaporates due to the absorption of heat generated by the PTC, the wick structure 346 acts to transfer the gas phase fluid 344" to the vapor channel 347. The gas phase working fluid 344" moves axially, for example Figure 3 The vapor passes through the vapor passage 347 and condenses at the distal end of the heat pipe tank 342 to enter the condensation portion S. 3CWhen condensing, the wick structure 346 is used to draw the fluid 344 out of the vapor channel 347. The liquid phase fluid 344' is pulled axially, for example, to the left under the capillary force, through the wick structure 346 to the evaporation portion S 1E to restart the cycle.

[0098] To help dissipate the heat energy discharged from the PTC 330 via the heat pipe 340, the heat-conducting rotor end cap 350 can be firmly mounted on the axial end of the rotor core 322 facing the PTC in a relationship adjacent to the heat-discharging longitudinal end of the heat pipe 340. It may be desirable that the rotor end cap 350 is manufactured with a set of circumferentially spaced heat pipe cavities 351 (e.g., one cavity per heat pipe) that thermally interact with the SEM heat pipe 340. Each heat pipe cavity 351 can be recessed in the radially inward facing surface of the rotor end cap 350, and the longitudinal tip of the corresponding heat pipe 340 is nested therein. These cavities 351 help increase the contact surface area between the end cap 350 and the heat pipe 340, thereby improving the conduction heat transfer rate between the interactive structures. In addition to helping to reduce windage losses and ensuring that the rotor winding 328 is supported for high-speed motor operation, the rotor end cap 350 also serves as a thermal body radiator for absorbing and dissipating the heat received from the heat pipe 340.

[0099] Continue to refer Figure 3 , the rotor end cap 350 may be manufactured with a set of end cap fins 354 designed to dissipate heat accumulated by the end cap 350 from the rotor assembly 318 and the PTC 330 into the internal coolant chamber 303 of the housing 302. Located on the outwardly facing axial surface of the rotor end cap 350, these heat transfer end cap fins 354 may be pin-type, flat-type, or corrugated-type fins that protrude axially away from the rotor core 322 and into the internal coolant chamber 303 of the housing. The end cap fins 354 increase the total surface area of ​​the rotor end cap 350 exposed within the housing 302 to increase the dissipation of the extracted thermal energy received by the rotor end cap 350, for example, via convection and, if desired, conductive heat transfer.

[0100] To help remove heat from the motor housing 302, an optional active thermal management (ATM) system (via oil pump 362) Figure 3354) can circulate a dielectric coolant fluid 352 in and out of the housing 302 to spray or jet cool the rotor end cap 350 and the end cap fins 354. The coolant fluid 352 can be a non-conductive, non-magnetic oil that is sprayed onto the stator windings 326 and the rotor end cap 350, for example, via a spray nozzle in the stator end cap 360 to accelerate the heat dissipation effect of the heat pipe 340 and the end cap 350. In addition to the enhanced convective cooling provided by the rotor end cap 350 and the end cap fins 354, the spraying / spraying of the coolant fluid 352 provides immersion-type conductive heat transfer. Spray / spray cooling for the rotor assembly 318 can also be directed to the stator assembly 316 to further improve the peak performance of the motor 310. For a spray cooling embodiment, it may be desirable to arrange a set of rotor pin fins in a spiral turbine-like pattern to excite the coolant fluid 352 to produce a desired spray effect during excitation of the rotor assembly 318.

[0101] During operation of a SEM-type motor 310 having a contact-based (brush-type) rotor PTC 330, the interface where the brushes 332A, 332B contact their respective slip rings 334A, 334B generates heat due to friction of the bristles sliding on the surface and resistance to large current amplitudes. The heat pipe 340 can be used at least in part to extract the heat generated at the slip ring and brush interface and transfer the extracted heat to a larger thermal mass, such as the rotor end cover 350. Cooling the rotor PTC 330 in this manner may help reduce the total number / size of brushes while increasing the current density of each brush while minimizing wear and drag on the brush-type PTC system. In addition, the brush holder assembly 314 can be manufactured as a molded plastic component that is susceptible to high temperatures; effectively extracting heat from the PTC area can help extend the expected operating life of the brush holder assembly 314 while increasing the peak current amplitude through the PTC 330.

[0102] The above article about Figure 3 The passive and active thermal management features described for the contact-type rotor PTC configuration can also be applied to remove heat from a non-contact-type rotor PTC. As a non-limiting example, in Figure 4 FIG. 4 shows a motor 410 having an inductive non-contact rotor PTC 430, while FIG. Figure 5 4 shows a motor 410 with a capacitive contactless rotor PTC 530. Unless otherwise expressly stated, the above reference Figure 3 The features and options described can be applied to Figure 4 and Figure 5 SEM architecture, where the same reference numerals are used to represent Figure 3 Same parts. Figure 4 For example, Figure 3The brushes 332A, 332B, slip rings 334A, 334B and accompanying hardware can be replaced by an electromagnetic induction coupler (rotary transformer) consisting of an annular outer "stationary" core 432 concentric with an annular inner "rotating" core 434 and the rotor shaft 306. The outer core 432 is rigidly fixed inside the PTC compartment 312 and carries an outer induction coil 436 exposed through the radial inner face of the core 432. The stationary core 432 surrounds the inner core 434, which is firmly mounted to the rotor shaft 306 to rotate in unison therewith and carries an inner induction coil 438, which electromagnetically cooperates with the outer induction coil 436. The rectifier PCB 470 and the supplementary rectifier heat sink 472 are operably connected to the inner core 434, which are also mounted to the rotor shaft 306 to rotate in unison therewith. Heat pipe 340 is thermally coupled to internal core 434 and rectifier PCB 470 to extract and dissipate their heat. Rectifier PCB 470 contains power electronic components that may generate a lot of heat, such as rectifier diodes. Using heat pipe 340 (or vapor chamber) to passively cool these components extends their expected operating life, achieves peak power, and helps reduce component size.

[0103] exist Figure 5 middle, Figure 3 The brushes 332A, 332B, slip rings 334A, 334B and accompanying hardware are replaced by a rotating capacitive coupler consisting of an outer "fixed" capacitive plate 532 axially spaced from and facing the inner "rotating" capacitive plate 534. The outer capacitive plate 532 is rigidly fixed inside the PTC compartment 312 and concentric with the rotor shaft 306. The inner capacitive plate 534 is coaxial with the outer capacitive plate 532 and is securely mounted to the rotor shaft 306 to rotate in unison with it. The rectifier PCB 570 and the supplementary rectifier heat sink 572 are operably connected to the inner capacitive plate 534, which are also mounted to the rotor shaft 306 to rotate in unison with it. The heat pipe 340 is thermally coupled to the capacitive plate 534 and the rectifier PCB 570 to extract and dissipate their heat. Passively cooling these components using heat pipes 340 (or vapor chambers) can help extend their operating life, enable higher power, and reduce component size.

[0104] Various aspects of the present disclosure have been described in detail with reference to the illustrated embodiments; however, those skilled in the art will recognize that many modifications may be made thereto without departing from the scope of the present disclosure. The present disclosure is not limited to the precise structures and compositions disclosed herein; any and all modifications, changes and variations apparent from the foregoing description are within the scope of the present disclosure as defined by the appended claims. Furthermore, the present concept expressly includes any and all combinations and sub-combinations of the foregoing elements and features.

Claims

1. A motor, comprising: case; a stator assembly including a stator core attached to the housing and an electromagnetic stator winding mounted to the stator core; a rotor assembly including a rotor core rotatably attached to the housing adjacent the stator assembly and an electromagnetic rotor winding mounted to the rotor core; a rotor power transfer circuit (PTC) attached to the housing, axially spaced from the rotor core and electrically connected to the rotor assembly to energize the rotor windings; a rotor shaft attached to the rotor core for rotation in unison therewith; as well as A heat pipe is mounted on the outer surface of the rotor shaft and protrudes axially between the rotor PTC and the rotor core, wherein the heat pipe is configured to passively extract heat energy from the rotor PTC and transfer the heat energy to outside the rotor PTC.

2. The motor according to claim 1, wherein: The heat pipe includes a plurality of heat pipes mounted on the outer surface and spaced circumferentially around the rotor shaft.

3. The motor according to claim 2, wherein: The heat pipe is adjacent to the outer surface and parallel to the rotor axis.

4. The motor according to claim 2, wherein: The heat pipes are parallel to each other and equidistantly spaced from each other.

5. The motor according to claim 2, wherein: The outer surface of the rotor shaft comprises a polymer surface coating, and wherein the heat pipe is at least partially embedded in the polymer surface coating. 6 . The electric machine of claim 2 , further comprising a thermal interface material (TIM) interposed between the heat pipe and the rotor PTC and electrically insulating the heat pipe and the rotor PTC.

7. The motor according to claim 2, wherein: The rotor PTC includes a plurality of electrical PTC components surrounding a rotor shaft, and wherein the heat pipe extends through a central cavity of the electrical PTC components and is thermally coupled to the electrical PTC components.

8. The motor according to claim 7, wherein: The electrical PTC component includes first and second brushes coupled to first and second slip rings, and wherein the heat pipe contacts the first and second slip rings.

9. The motor according to claim 1, wherein: The heat pipe includes a sealed can containing a working fluid configured to undergo a phase change between a liquid phase and a gas phase to extract thermal energy from the rotor PTC and transfer the thermal energy out through an axial end of the rotor PTC.

10. The electric machine according to claim 9, wherein: The heat pipe also includes a wick structure located inside the sealed can and configured to transfer the working fluid from the first axial end to the second axial end of the sealed can when in a liquid phase.

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