Direct contact cooling of axial flux motor stators

Abstract

A stator assembly for an axial flux electric machine includes a heat exchanger jacket configured to circulate a heat transfer fluid. The stator also includes a plurality of stator cores, each stator core having an electrically conductive winding, an electrically insulating material disposed over at least a portion of the electrically conductive wire winding, and a molded soft magnetic composite (SMC) material. The heat exchanger jacket is circumferentially disposed around at least a portion of the periphery of the stator. Each stator core defines an outer peripheral surface configured to contact the heat exchanger jacket, and at least a portion of the outer peripheral surface is defined by the molded soft magnetic composite (SMC) material. A method for manufacturing a molded soft magnetic composite (SMC) material stator core is also provided.

Description

Technical Field

[0001] The present disclosure relates generally to stators for axial flux electric machines, and more particularly to stators having magnetic core components designed to enhance heat transfer with adjacent heat exchanger components. Background Art

[0002] This section provides background information related to the present disclosure which is not necessarily prior art.

[0003] Electric motors convert electrical energy into mechanical work by producing torque. Electric vehicles, including hybrid vehicles, use electric motors (such as induction motors and permanent magnet motors) to propel the vehicle and capture braking energy when used as generators. Generally speaking, an electric motor includes a rotor that rotates during operation and a stator that is stationary. The rotor may contain multiple permanent magnets and rotates relative to the fixed stator. The rotor is connected to a rotor shaft that also rotates with the rotor. The rotor, which includes permanent magnets, is separated from the stator by a predetermined air gap.

[0004] The stator includes conductors in the form of wire windings. When electrical energy is applied through the conductive wire windings, a magnetic field is generated. When electrical energy or power is fed to the conductive wire windings of the stator, power can be transferred across the air gap (between the stator and the rotor) by a magnetic flux that creates a torque acting on the permanent magnets in the rotor. In this way, mechanical power can be transferred to or extracted from the rotating rotor shaft. In an electric vehicle, the rotor thus transmits torque to the drive wheels of the vehicle via the rotating shaft through a gear set.

[0005] Two common types of electric motors include radial flux or axial flux type motors. In a radial flux motor, the rotor and stator are typically in a concentric or nested configuration such that when the stator is energized, it generates a magnetic flux that extends radially from the stator to the rotor. Therefore, the conductive windings in the stator are typically arranged perpendicular to the axis of rotation so that a magnetic field is generated that is oriented in a radial direction from the axis of rotation (along the rotor axis). In an axial flux motor, a magnetic field parallel to the axis of rotation is generated by windings of conductive wire in the stator so that the magnetic flux extends parallel to the axis of rotation (parallel to the rotor axis). In certain applications, an axial flux motor is desired because it is relatively lightweight, generates increased power, and has a compact size compared to a radial flux motor.

[0006] The operation of the electric motor generates heat due to resistance, iron losses and mechanical friction in the rotor and stator. The stator and rotor are usually cooled to avoid overheating, which can cause demagnetization of the magnets and / or thermal damage to the stator, rotor and other motor components. For radial flux motors, external liquid cooling jackets are used to dissipate heat from the motor. However, for axial flux motors, especially axial flux motors with a stator disposed between two external rotors, external liquid cooling jackets are not efficient in dissipating heat without losing the compact form factor of the axial flux motor. Therefore, axial flux motors generally avoid the use of external cooling jackets. In contrast, many conventional axial flux motors rely on internal fan blades / heat exchange fins bonded to the outer surface of the rotor for air cooling. However, the motor efficiency is reduced due to windage losses caused by air cooling. Therefore, although the air-cooled axial flux motor achieves its intended purpose, it is desirable to have more efficient cooling of the axial flux motor while maintaining the desired compact form factor. Summary of the invention

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] The present disclosure relates to a stator assembly for an axial flux electric machine. In certain variations, the stator assembly includes a heat exchanger jacket configured to circulate a heat transfer fluid and a stator. The stator includes a plurality of stator cores. Each stator core includes an electrically conductive winding, an electrically insulating material disposed over at least a portion of the electrically conductive wire winding, and a molded soft magnetic composite material. The heat exchanger jacket is circumferentially disposed around at least a portion of the periphery of the stator. Each stator core defines an outer peripheral surface configured to contact the heat exchanger jacket, and at least a portion of the outer peripheral surface is defined by the molded soft magnetic material.

[0009] In one aspect, a first portion of the peripheral surface is defined by a molded soft magnetic material and a second portion of the peripheral surface is defined by an electrically insulating material.

[0010] In another aspect, the second portion is a central region of the peripheral surface and the first portion defines at least two outer regions of the peripheral surface.

[0011] In another aspect, the molded soft magnetic material defines at least one central recessed area configured to receive an electrically conductive wire winding. Electrically insulating material is disposed over the electrically conductive wire winding and the molded soft magnetic material defines protruding flanges on either side of the at least one central recessed area.

[0012] In an alternative aspect, the first portion is a central region of the peripheral surface and the second portion defines at least two outer regions of the peripheral surface.

[0013] In another aspect, the molded soft magnetic material extends between adjacent stator cores of the plurality of stator cores.Thus, the stator has a yoke design.

[0014] In one aspect, the peripheral surface is defined by a molded soft magnetic (SMC) material having gaps disposed therein.

[0015] In another aspect, the gap is centrally disposed within the outer peripheral surface.

[0016] In another aspect, the molded soft magnetic material defines a recess below the outer peripheral surface that receives the electrically conductive wire windings and the electrically insulating material disposed therein.

[0017] In one aspect, the plurality of stator cores are physically separated from each other.Thus, the stator has a yokeless design.

[0018] In one aspect, a molded soft magnetic material defines a core having at least one recessed region configured to receive an electrically conductive wire winding and an electrically insulating material disposed thereon.

[0019] In another aspect, the molded soft magnetic material has a mass fraction of greater than or equal to about 7.4 kg / m 3 The molded soft magnetic material has a first density of greater than or equal to about 7.0 kg / m 3 to less than or equal to approximately 7.4 kg / m 3 of the second density.

[0020] In one aspect, the soft magnetic composite material has a plurality of magnetic particles comprising iron.

[0021] In one aspect, the electrically insulating material is selected from the group consisting of epoxy, glass, porcelain, silicone rubber, EPDM, composite materials, and combinations thereof.

[0022] In one aspect, an axial flux electric machine comprises a stator assembly as described above and at least one rotor comprising a plurality of magnets, and an air gap is defined between the stator and the at least one rotor.

[0023] The present disclosure also relates to a method for manufacturing a stator core component for an axial flux motor. In certain variations, the method may include: introducing a soft magnetic composite (SMC) precursor into a cavity of a mold including a first region and a second region. The soft magnetic composite (SMC) precursor includes a polymer precursor and a plurality of magnetic or ferromagnetic particles. The method also includes: compressing the soft magnetic composite (SMC) precursor in the cavity by simultaneously applying a first pressure greater than or equal to about 800 MPa by a first pressure head in the first region and a second pressure greater than or equal to about 300 MPa to less than or equal to about 600 MPa by a second pressure head in the second region. Then, the consolidated soft magnetic composite (SMC) material component is removed from the cavity. The consolidated soft magnetic composite (SMC) material component has a first density corresponding to the first region where the first pressure is applied and a second density corresponding to the second region where the second pressure is applied.

[0024] In one aspect, two consolidated soft magnetic composite (SMC) material components are bonded together to form a stator core, and the method further includes applying an electrically conductive winding about the stator core and disposing an electrically insulating material over at least a portion of the electrically conductive wire winding.

[0025] In one aspect, the plurality of magnetic or ferromagnetic particles comprises a core of magnetic or ferromagnetic material surrounded by a shell comprising one or more insulating layers.The magnetic or ferromagnetic material comprises a material selected from the group consisting of iron, samarium, neodymium, cobalt, aluminum, alloys, and combinations thereof.

[0026] In one aspect, the first density is greater than or equal to about 7.4 kg / m 3 and the second density is greater than or equal to about 7.0 kg / m 3 to less than or equal to approximately 7.4 kg / m 3 .

[0027] The present disclosure also relates to a stator assembly for a yoke axial flux motor, comprising a heat exchanger jacket configured to circulate a heat transfer fluid. The stator assembly also includes a stator, which includes a plurality of stator cores. Each stator core includes a conductive winding, an electrically insulating material disposed on at least a portion of the conductive wire winding, and a magnetic region, the magnetic region comprising a molded soft magnetic composite material or a plurality of laminated magnetic steel layers. The magnetic region includes a central protrusion extending between and connecting the plurality of stator cores. The heat exchanger jacket is circumferentially disposed around at least a portion of the outer periphery of the stator. Each stator core defines an outer peripheral surface configured to contact the heat exchanger jacket, and at least a portion of the outer peripheral surface is defined by the magnetic region.

[0028] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0030] Figure 1 A representative axial flux machine having a central stator and two rotors is shown;

[0031] Figure 2 is a partial cross-sectional view of an axial flux electric machine stator having a yokeless design and a heat exchanger jacket for transferring heat from a stator core component;

[0032] Figure 3 is a partial cross-sectional view of an axial flux electric machine stator assembly having a yokeless design prepared according to certain aspects of the present disclosure, the axial flux electric machine stator assembly including an improved magnetic portion formed of a molded soft magnetic composite material, the improved magnetic portion defining an outer peripheral contact surface for contacting a heat exchanger jacket having enhanced heat transfer capabilities;

[0033] Figure 4 yes Figure 3 A side cross-sectional view of an axial flux motor stator assembly in FIG.

[0034] Figure 5 A process for making an improved molded soft magnetic composite component for an axial flux electric machine assembly having enhanced heat transfer capabilities is shown according to certain aspects of the present disclosure;

[0035] Figure 6 is a partial cross-sectional view of an axial flux electric machine stator assembly having a yokeless design prepared according to certain aspects of the present disclosure, the axial flux electric machine stator assembly including another variation of an improved magnetic portion formed of a molded soft magnetic composite material defining an outer peripheral contact surface for contacting a heat exchanger jacket, the outer peripheral contact surface having enhanced heat transfer capabilities;

[0036] Figure 7 yes Figure 6 A side cross-sectional view of an axial flux motor stator assembly in FIG.

[0037] Figure 8is a partial cross-sectional view of an axial flux electric machine stator assembly having a yoke design prepared in accordance with certain aspects of the present disclosure, the axial flux electric machine stator assembly including another variation of an improved magnetic portion defining a centrally disposed projection defining a portion of a peripheral contact surface for contacting a heat exchanger jacket having enhanced heat transfer capabilities; and

[0038] Fig. 9 yes Figure 8 Side cross-sectional view of an axial flux motor stator assembly.

[0039] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0040] Exemplary embodiments are provided so that the present disclosure will be more comprehensive and the scope of the present invention will be fully communicated to those skilled in the art. Many specific details, such as examples of specific components, parts, devices and methods, are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the specific details need not be adopted, and that the exemplary embodiments can be implemented in many different forms, and none of this constitutes a limitation on the scope of the present disclosure. In some exemplary embodiments, known processes, known device structures and known technologies are not described in detail.

[0041] The terms used herein are only used to describe specific exemplary embodiments and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprise", "comprising", "including" and "having" are inclusive and thus specify the presence of the described features, elements, components, steps, integers, operations and / or parts, but do not exclude the presence or absence of one or more other features, integers, steps, operations, elements, parts and / or groups thereof. Although the open term "comprising" should be understood as a non-limiting term used to describe and claim the various embodiments set forth herein, in some aspects, the term may alternatively be understood as a more restrictive and constraining term, such as "consisting of" or "consisting essentially of". Therefore, for any given embodiment that mentions ingredients, materials, components, elements, features, integers, operations and / or process steps, the present disclosure also specifically includes embodiments that are composed of or essentially consist of these mentioned ingredients, materials, components, elements, features, integers, operations and / or process steps. In the case of “consisting of,” alternative embodiments exclude any additional ingredients, materials, components, elements, features, integers, operations and / or process steps, while in the case of “consisting essentially of,” any additional ingredients, materials, components, elements, features, integers, operations and / or process steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any ingredients, materials, components, elements, features, integers, operations and / or process steps that do not materially affect the basic and novel characteristics may be included in the embodiments.

[0042] Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be employed unless otherwise indicated.

[0043] When a part, element or layer is referred to as being "on", "engaged to", "connected to" or "coupled to" another element or layer, it may be directly on, directly engaged to, connected to or coupled to the other parts, elements or layers, or there may be intermediate elements or layers. In contrast, when an element is referred to as being "directly" "on", "directly engaged to", "directly connected to" or "directly coupled to" another element or layer, there are no intermediate elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0044] Although the term first, second, third etc. can be used here to describe various steps, elements, components, regions, layers and / or sections, these steps, elements, components, regions, layers and / or sections should not be limited by these terms unless otherwise indicated. These terms can only be used to distinguish a step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as "first", "second" and other numerical terms do not imply a sequence or order when used here, unless the context clearly indicates this. Therefore, the first step, element, component, region, layer or section discussed hereinafter can be referred to as the second step, element, component, region, layer or section and can not deviate from the teaching of exemplary embodiments.

[0045] For ease of description, spatial or temporal relative terms, such as "before", "after", "inside", "outside", "below", "below", "below", "above", "upper", etc., may be used herein to describe the relationship of one element or feature relative to another element or feature as shown in the figures. The spatial or temporal relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation shown in the figures.

[0046] Throughout this disclosure, numerical values ​​represent approximate measurements or limits of ranges to cover minor deviations from given values ​​and embodiments having approximately the stated values ​​and embodiments having exactly the stated values. Except in the working examples provided at the end of the specific embodiments, all numerical values ​​of parameters (such as quantities or conditions) in this specification (including the appended claims) are to be understood as being modified by the term "approximately" in all cases, regardless of whether "approximately" actually appears before the numerical value. "Approximately" means that the numerical value allows for slightly slight imprecision (slightly close to the accuracy of the value; approximately or reasonably close to the value; approximately). If the imprecision provided by "approximately" is not otherwise understood in the art to have this ordinary meaning, the "approximately" used here means at least possible variations caused by the ordinary methods of measuring and using such parameters. For example, "approximately" may include the following variations: less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and optionally less than or equal to 0.1% in some aspects.

[0047] Additionally, the disclosure of a range includes disclosure of all values ​​within the entire range and further subdivided ranges, including the endpoints and sub-ranges given for the range.

[0048] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0049] In various aspects, the present disclosure relates to axial flux electric machines with improved cooling efficiency, such as liquid-cooled axial flux electric machines. As background, Figure 1 1 shows a non-limiting example of an electric device in the form of an axial flux electric machine 100, which is also referred to as a pancake motor. The electric machine 100 has a first rotor 110 and a second rotor 120, both connected to a rotor shaft 130 and configured to rotate about the rotor shaft 130. The first rotor 110 and the second rotor 120 each have an annular or disc shape with a centrally disposed hole 118. The rotor shaft 130 passes through the centrally disposed hole 118. The rotor shaft 130 defines an axis of rotation 132 about which the rotors rotate.

[0050] The stator 140 is disposed between the first rotor 110 and the second rotor 120. The stator 140 may have an annular or disc shape. The stator 140 is fixed and stationary, while the first rotor 110 and the second rotor 120 rotate during operation on the rotor shaft 130. The first rotor 110 faces a first side 142 of the stator 140 and defines a first air gap 144 therebetween. The second rotor 120 faces a second side 146 of the stator 140 and defines a second air gap 148 therebetween.

[0051] Although the motor 100 is shown as having a central single stator 140 and two outer rotors 110, 120, as will be appreciated by those skilled in the art, other configurations are also contemplated, including configurations having two stators and a single rotor or in which the motor assembly may include more or fewer rotors and / or stators and the description herein also applies to these other embodiments. In addition, although not currently shown, the skilled artisan will appreciate that in various aspects, the motor assembly may also include a housing and the rotor and stator and the shaft may be disposed within the housing. In some aspects, the housing may be fixed to the vehicle frame and the shaft may be coupled to a gearbox within the vehicle, such as a reduction gearbox.

[0052] Each of the first rotor 110 and the second rotor 120 can have the same design (facing the stator 140 in opposite directions) and therefore the common parts will be described here. Each of the first rotor 110 and the second rotor 120 includes a plurality of permanent magnets 112 fixed to a rotor body 114. The permanent magnets 112 can have alternating polarities. Each permanent magnet 112 defines a channel 116 therebetween, which can extend radially along the face of the corresponding rotor. In this way, the permanent magnets 112 and the channels 116 can together define a plurality of magnetic poles.

[0053] The stator 140 includes a plurality of stator segments or core members 150 around which a plurality of conductive wire windings 152 are wound. The stator 140 defines a plurality of slots 156 between respective stator core members 150, wherein the conductive wire windings 152 may extend over or bridge the slots 156. The stator 140 may be fixed and stationary. Although not shown, other winding configurations and techniques as understood in the art are contemplated. For example, in some aspects, the slots 156 may be configured to receive a plurality of conductive wire windings 152 that are wound in and through the slots 156. The conductive wire windings 152 may include copper or a copper alloy.

[0054] The rotor shaft 130 may pass through a centrally disposed hole 154 in the stator 140 and be supported by a bearing that aligns the rotors 110, 120 with respect to the stator 140 while allowing the rotor shaft 130 to rotate. As described above, the plurality of conductive wire windings 152 of the stator 140 may be constructed of copper or other conductive wires configured to generate a magnetic field when current is applied to interact with the magnetic fields of the plurality of permanent magnets 112 having alternating magnetic poles located on the first and second rotors 110, 120. Different regions of the stator 140 may be selectively energized to exert a rotational force on the first and second rotors 110, 120, thereby causing the rotors 110, 120 and the rotor shaft 130 to rotate relative to the axis of rotation 132. An axial flux electric machine 100 having a single stator 140 and first and second rotors 110, 120 can be used in high torque applications, including in electric or hybrid vehicles. In such a variation, the housing surrounding the motor 100 may be attached to the vehicle frame, and at least one output from the end of the rotor shaft 130 coupled to a reduction gearbox or directly to the vehicle drive wheels. The vehicle application of the axial flux motor 100 is provided as an exemplary embodiment and is not intended to be limiting.

[0055] Figure 2 A cross-sectional view of a conventional yokeless stator core design is shown. The stator 200 includes a plurality of stator cores 210 physically separated by a plurality of channels or slots 212. A plurality of conductive wire windings 214 are wound around each respective stator core 210. Each stator core 210 defines a central magnetic region 216, which may be formed of a magnetic or ferromagnetic material such as a laminated steel structure (a laminated stator core central region having multiple layers of ferromagnetic material (such as magnetic steel)) or a soft magnetic composite material. The stator 200 is a yokeless design in that the plurality of stator cores 210, and in particular the central magnetic region 216, are not yoked together via physical connections between the stator cores 210, but are instead completely separated by the slots 212.

[0056] A peripheral surface configured to contact an adjacent component or peripheral contact surface 220 is defined by each of the plurality of stator cores 210. Each conductive wire winding 214 is surrounded by an electrically insulating material 222, such as an epoxy material, on three of the four sides. Other insulating materials may include glass, porcelain, or polymer composites, such as where the central region (e.g., rod) is made of fiber reinforced plastic and the outer jacket includes silicone rubber or ethylene propylene diene monomer (EPDM). By enclosing the conductive wire winding 214 in the electrically insulating material 222, selected peripheral areas of the stator 200 are protected from the effects of current or potential in the conductive wire winding 214, while the central magnetic region 216 of the stator core 210 remains exposed to the conductive wire winding 214 to induce a magnetic field therein. In conventional designs such as those shown here, the electrically insulating material 222 defines the peripheral contact surface 220.

[0057] A heat exchanger component in the form of a heat exchanger jacket 230 is disposed adjacent the peripheral contact surface 220 and thus along at least a portion of the circumferential portion of the stator 200. The heat exchanger jacket 230 may be formed of a thermally conductive material such as metal and also has a plurality of built-in cooling channels 232 through which a liquid / fluid heat transfer medium can circulate. Suitable heat transfer media may include water. The heat transfer medium may be circulated by a pumping device (not shown).

[0058] As mentioned above, axial motors deliver high torque density due to their axial flux topology and generate a lot of heat. However, it is difficult to cool a segmented stator with concentrated windings because the water jacket does not come into direct contact with the heat generating parts of the stator core. For example, in Figure 2 In the design shown, the peripheral contact surface 220 is formed of an electrically insulating material 222 that typically has a very low thermal conductivity. For example, an epoxy material may have a thermal conductivity of approximately 0.35 w / m·K. Therefore, the amount of heat transfer and cooling that occurs between the plurality of stator cores 210 through the peripheral contact surface 220 to the heat exchanger jacket 230 may be greatly increased. As described above, some axial flux machine designs forgo the use of a cooling jacket and instead use protruding fins to transfer heat from the stator.

[0059] Figure 3 and Figure 4 An example of a stator 250 for an axial flux electric machine prepared according to certain aspects of the present disclosure is shown. Figure 2 The stator in Figure 3A yokeless stator core design is shown. The stator 250 includes a plurality of stator cores 260 physically separated by a plurality of channels or slots 262. Thus, the stator 250 is a yokeless design because the plurality of stator cores 260 are separate from one another and are not yoked together via a physical connection. A plurality of conductive wire windings 264 are wound around each respective stator core 260. Each stator core 260 defines a magnetic portion 266, which may define a central region of each stator core 260 and may be formed of a magnetic or ferromagnetic material. According to certain aspects of the present disclosure, the magnetic portion 266 of each stator core 260 comprises a soft magnetic composite (SMC) material. The SMC powder comprises a soft magnetic material, the surface of which may be covered with an electrically insulating layer.

[0060] In some aspects, the precursor of the molded soft magnetic composite material includes particles defining a magnetic core surrounded by one or more insulating layers in a shell region. The magnetic material in the core can be a ferromagnet and include iron (e.g., iron or ferrite powder) or other magnetizable materials or alloys, for example, including iron alloys including silicon, nickel and / or phosphorus. Other examples include rare earth metal compounds, such as compounds including samarium (Sm), neodymium (Nd), such as samarium cobalt (SmCo 1:5), samarium cobalt (SmCo 2:17) and neodymium iron boron (NdFeB). Other examples of suitable magnetic particles include aluminum nickel cobalt (AlNiCo) alloys. In some aspects, the average particle diameter of the magnetic particles can be greater than or equal to about 50 microns to less than or equal to about 250 microns, and in some aspects optionally about 100 microns. The core region including the magnetic material may be surrounded by one or more insulating layers, which are non-magnetic materials, such as siloxane-based materials such as silicone varnish, or metal organic or inorganic insulating materials, such as silicate layers, oxide layers, phosphate layers, and equivalents and combinations thereof. In some aspects, the insulating shell layer(s) may have a total thickness of greater than or equal to about 10 nm to less than or equal to about 1 millimeter, and in some aspects the total thickness is optionally greater than or equal to about 10 nm to less than or equal to about 800 microns.

[0061] These powders are solidified by means of pressing or consolidation to form soft magnetic parts. Therefore, such SMC materials can be easily formed into various different and complex shapes. The precursor of the soft magnetic composite material can include, for example, ferromagnetic powder particles and an optional matrix material, such as a polymer resin.

[0062] An electrically insulating material 270, such as an epoxy material, is disposed on and in contact with the outer peripheral side 272 of the conductive wire winding 264. Other suitable electrically insulating materials are also contemplated, such as glass, porcelain, or polymeric composites, for example where the central region (e.g., rod) is made of fiber reinforced plastic and the outer jacket comprises silicone rubber or EPDM. Thus, the electrically insulating material 270 may be selected from the group consisting of epoxy, glass, porcelain, siloxane-based silicone rubber, EPDM, composite materials, and combinations thereof.

[0063] However, the lateral sides 274 of the conductive wire windings 264 may be adjacent to and optionally contact the SMC material forming the magnetic portion 266. Each stator core 260 defines a peripheral contact surface 280. Figure 3 and Figure 4 In the illustrated embodiment, a portion of the peripheral contact surface 280 is defined by the SMC material of the magnetic portion 266. A second portion of the peripheral contact surface 280 is defined by the electrically insulating material 270. As shown, the electrically insulating material 270 occupies a central region 280A of the peripheral contact surface 280, while the SMC material in the magnetic portion 266 defines at least two outer regions 280B of the peripheral contact surface 280.

[0064] More specifically, if Figure 4 As best shown in FIG. 1 , the magnetic portion 266 comprising an SMC material is molded to define at least one central recessed area 282 configured to receive the conductive wire winding 264. The electrically insulating material 270 is disposed on the conductive wire winding 264 and the molded soft magnetic material of the magnetic portion 266 defines protruding flanges or walls 284 on both sides of the at least one central recessed area 282.

[0065] The stator 250 also includes a heat exchanger jacket 290 that is configured to circulate a heat transfer fluid or liquid within a plurality of built-in channels 292. The heat exchanger jacket is circumferentially disposed around at least a portion of the periphery of the stator 250, and more specifically around a portion of the plurality of stator cores 260. Thus, each peripheral contact surface 280 of each stator core 260 is in heat transfer relationship and in some aspects can be configured to contact the heat exchanger jacket 290. It should be noted that each peripheral contact surface 280 does not necessarily need to contact an adjacent heat exchanger jacket 290, but rather each is adjacent to and in heat transfer relationship with an adjacent heat exchanger jacket 290, although in some variations physical contact can enhance heat transfer.

[0066] The SMC material in the magnetic portion 266 has a high thermal conductivity. For example, the SMC material may have a thermal conductivity greater than or equal to about 20 w / m·K, optionally greater than or equal to about 21 w / m·K, optionally greater than or equal to about 22 w / m·K, optionally greater than or equal to about 23 w / m·K, optionally greater than or equal to about 24 w / m·K, optionally greater than or equal to about 25 w / m·K, and optionally greater than or equal to about 26 w / m·K in some variations. As a non-limiting example, the SMC material has a thermal conductivity of about 26 w / m·K, wherein the composition of the SMC material includes iron powder particles coated with an electrical insulation layer. In this way, because a portion of the peripheral contact surface 280 (here, the outer region 280B defined by the magnetic portion 266 formed by the SMC material) has a greater thermal conductivity, the heat transferred from the plurality of stator cores 260 to the heat exchanger jacket 290 is significantly increased. As a non-limiting example, heat transfer may be increased by at least a factor of ten and in some aspects by a factor of several dozen.

[0067] It should also be noted that Figure 3 and Figure 4 The amount of magnetic leakage that occurs with the design shown in is relatively very small, for example, when calculating the total magnetic flux that occurs in the peripheral region of the magnetic portion 266 (such as in the vicinity of the conductive wire windings 264 and the peripherally extending flange 284) relative to the overall magnetic flux of the magnetic portion / entire stator core 260, the magnetic leakage is less than or equal to about 0.56%. It should be noted that in some variations, the material disposed in the peripheral region of the magnetic portion 266 may have different properties than the central region of the core, such as a different density, permeability, or a composition with a different amount of components. In one embodiment, the first density of the magnetic portion / entire stator core 260 is greater than or equal to about 7.4 kg / m 3 , and a second density in the edge region including the flange 284 is less than the first density, for example, greater than or equal to about 7.0 kg / m 3 to less than or equal to approximately 7.4 kg / m 3 .

[0068] Figure 5 shows the method for generating Figure 3 and Figure 4300 is a representative molding process for the magnetic portion of the stator core of the stator in the axial flux motor shown in FIG. The mold 310 defines a cavity 312 having a shape corresponding to half of the magnetic portion of the stator core. The cavity 312 defines a first region 314 corresponding to the center of the stator core and a second region 316 corresponding to an outer region or flange defining a portion of the peripheral contact surface of the stator core. Therefore, the first region 314 is deeper than the second region 316 and has a larger volume than the second region 316. The cavity 312 is filled with an SMC material precursor 318, for example, a plurality of magnetic or ferromagnetic particles. Resin powder or another polymer precursor may also be introduced into the cavity 312. The resin and particles may be premixed to form a homogenous mixture. Although not shown, as will be appreciated by those skilled in the art, an apparatus for automatically conveying and introducing the SMC material precursor 318 may be associated with the mold 310.

[0069] For example, the SMC material precursor 318 can be densified by applying a compressive force to the mold 310. The press 320 may include a plurality of components, namely a first pressure head 322 and a second pressure head 324. According to certain aspects of the present disclosure, the first pressure head 322 may apply a different level of compressive force from the second pressure head 324, thereby resulting in different densification levels of the SMC material precursor 318. For example, the first pressure head 322 may apply a first pressure greater than or equal to about 800 MPa in the first region 314 of the mold cavity 312. The second pressure head 324 may apply a second pressure less than the first pressure to the SMC precursor material 318 in the second region 316. For example, the second pressure may be greater than or equal to about 300 MPa to less than or equal to about 600 MPa. As described above, after the pressing process, the first density in the first region 314 is greater than or equal to about 7.4 kg / m 3 , and the second density in the second region 316 is less than the first density, for example, greater than or equal to about 7.0 kg / m 3 to less than or equal to approximately 7.4 kg / m 3 It should also be noted that in some variations, the material composition in the first region 314 may be different from the material composition in the second region 316, for example, the second region 316 may have a smaller amount of magnetic components than the first region 314. In addition, different product families can be compressed by powder particles of different sizes, wherein the different product families have different magnetic flux permeabilities.

[0070] Although not shown, additional equipment for applying heat and / or actinic radiation may be used to react, e.g., polymerize or crosslink, the SMC composite matrix as desired. The molding process 300 may be repeated to form two solid, dense SMC material components 330. The two solid, dense SMC material components 330 can then be joined together to form a magnetic portion. In certain variations, to enhance adhesion of the solid, dense SMC material components 330, an adhesive or glue may be further applied at the interface therebetween to form the magnetic portion of the stator core (see Figure 3 and Figure 4 Although not shown, conductive wire windings may then be wound around each stator core (e.g., in recessed areas 332 formed when the solid, dense SMC material components 330 are joined together), and electrically insulating material may then be disposed or molded onto the conductive windings ( Figure 5 These forming steps can be performed in an automated process.

[0071] Figure 6 and Figure 7 An example of a stator 350 for an axial flux electric machine prepared according to certain aspects of the present disclosure is shown. Figure 6-Figure 7 Another yokeless stator core design is shown. The stator 350 includes a plurality of stator cores 360 physically separated by a plurality of channels or slots 362. Thus, the stator 350 is a yokeless design because the plurality of stator cores 360 are separate from one another and are not yoked together via a physical connection. A plurality of conductive wire windings 364 are wound around each respective stator core 360. Each stator core 360 ​​defines a magnetic portion 366, which may define a main or central region of each stator core 360 ​​and may be formed of a magnetic or ferromagnetic material. According to certain aspects of the present disclosure, the magnetic portion 366 of each stator core 360 ​​comprises a soft magnetic composite (SMC) material, as previously described.

[0072] An electrically insulating material 370, such as an epoxy material, is disposed on and in contact with the outer peripheral sides 372 of the conductive wire windings 364 to provide electrical isolation for the windings. However, the lateral sides 374 of the conductive wire windings 364 may be adjacent to and optionally contact the SMC material forming the magnetic portion 366. Each stator core 360 ​​defines an outer peripheral contact surface 380. Figure 6 and Figure 7In the illustrated embodiment, a first portion 380A of the peripheral contact surface 380 is defined by the SMC material of the magnetic portion 366. More specifically, the area of ​​the peripheral contact surface 380 for establishing contact with the adjacent component is defined by the magnetic portion, but there is a gap 380B defined in the peripheral contact surface 380. As shown, the gap 380B is on the peripheral contact surface 380. The optional gap 380B can be used to reduce magnetic flux leakage at the peripheral contact surface 380. In some variations, the size of the gap is larger than the air gap (h) defined between the stator and the adjacent rotor. g ).

[0073] The magnetic portion 366 comprising an SMC material is molded to define at least one central recessed area 382 configured to receive the conductive wire winding 364. The electrically insulating material 370 is disposed on the conductive wire winding 364 and the molded soft magnetic material of the magnetic portion 366 defines protruding walls 384 on both sides of the at least one central recessed area 382, ​​the protruding walls being integrally connected to a covered area 386 extending over a portion of the central recessed area 382. In this manner, the magnetic portion 366 defines a central recessed area having sides with a cross-sectional L-shape, the sides defining a gap 368 therebetween. Thus, the conductive wire winding 364 and the electrically insulating material 370 are disposed within the central recessed area 382 defined by the magnetic region. The magnetic region extending over the conductive wire winding 364 and the electrically insulating material may have a thickness of greater than or equal to about 3 mm to less than or equal to about 10 mm. The gap 368 has a length greater than the axial length of the air gap, so that the length of the gap 368 can be greater than or equal to about 2 mm to less than or equal to about 20 mm. The presence of the gap 368 can minimize magnetic flux leakage in the path through the covered area 386. Therefore, the covered area 386 of the magnetic portion 366 of the stator core 360 ​​covers both the top and bottom surfaces of the conductive wire winding 364 (the electrically insulating material 370 is disposed on one side of the conductive wire winding 364). In some variations, the magnetic portion 366 formed of the SMC material can be manufactured by overmolding around the insulated coil (conductive wire winding 364).

[0074] The stator 350 also includes a heat exchanger jacket 390 that is configured to circulate a heat transfer fluid or liquid within a plurality of built-in channels 392. The heat exchanger jacket 390 is circumferentially disposed around at least a portion of the periphery of the stator 350, and more specifically around a portion of the plurality of stator cores 360. Thus, each peripheral contact surface 380 of each stator core 360 ​​is in a heat transfer relationship and is configured in some aspects to contact the heat exchanger jacket 390. As previously described, the SMC material in the magnetic portion 366 has a high thermal conductivity. Therefore, because a majority of the peripheral contact surface 380 (here, the first portion 380A defined by the magnetic portion 366 formed of the SMC material) has a greater thermal conductivity than the electrically insulating material, the amount of heat transferred from the plurality of stator cores 360 to the heat exchanger jacket 390 is significantly increased. As a non-limiting example, heat transfer can be increased by at least ten times and in some aspects by several dozen times. It should also be noted that Figure 6 and Figure 7 The amount of magnetic leakage that occurs with the illustrated design is relatively very small, such as less than or equal to about 0.3% when calculating the total magnetic flux occurring in the peripheral region of the magnetic portion 366 (such as the total magnetic flux in the wall 384 and the covered area 386 extending near and above the conductive wire windings 364) relative to the overall magnetic flux of the magnetic portion / entire stator core 360. As mentioned above, it should be noted that in certain variations, the material disposed in the peripheral region of the magnetic portion 366 may have different properties than the central region of the core, such as a different density, permeability, or a composition having a different amount of a component.

[0075] Figure 8 and Fig. 9 An example of yet another stator 450 for an axial flux electric machine prepared according to certain aspects of the present disclosure is shown. Figure 8 and Fig. 9 A yoked stator core design is shown. The stator 450 includes a plurality of stator cores 460 that are partially separated by a plurality of channels or slots 462. However, as further described herein, the plurality of stator cores 460 are also physically connected or yoked together to each other in at least one area.

[0076] A plurality of conductive wire windings 464 are wound around each respective stator core 460. Each stator core 460 defines a magnetic portion 466, which may define a main or central region of each stator core 460 and may be formed of a magnetic or ferromagnetic material. According to certain aspects of the present disclosure, the magnetic portion 466 of each stator core 460 comprises a magnetic or ferromagnetic material. As described above, the magnetic or ferromagnetic material may be a molded magnetic composite (SMC) material. Alternatively, the magnetic or ferromagnetic material may include a laminated stator core component having multiple layers of ferromagnetic material, such as magnetic steel. Such layers of ferromagnetic material are typically separated from each other by insulating material interposed therebetween. The laminated steel sheets may be stamped, optionally annealed and stacked during the manufacturing process to form laminated stator core components. When a plurality of laminated stator core components are assembled together, they form a plurality of magnetizable poles.

[0077] As shown, the plurality of conductive wire windings 464 are distributed on both sides of each respective stator core 460. Thus, a first side 467 of the stator core 460 has a first plurality of conductive wire windings 464A. A second side 469 of the stator core 460 has a second plurality of core members 464B.

[0078] An electrically insulating material 470, such as an epoxy material, is disposed on and in direct contact with the outer peripheral sides 472 of the conductive wire windings 464. However, the lateral sides 474 of the conductive wire windings 464 may be adjacent to and optionally in contact with the SMC material forming the magnetic portion 466.

[0079] The magnetic portion 466 comprising an SMC material is molded to define at least one central protruding area 482. The molded soft magnetic material of the magnetic portion 466 further defines two seat areas 484 on both sides of the at least one central protruding area 482. The two seat areas 484 are configured to receive the conductive wire windings 464. Therefore, the conductive wire windings 464 and the electrically insulating material 470 are placed in the two seat areas 484 defined by the magnetic area. The at least one protruding area 482 has a rectangular shape and extends radially outward toward the outer periphery of the stator 450. The protruding area can have an axial length greater than or equal to about 3 mm to less than or equal to about 20 mm. As described above, the at least one protruding area 482 of the magnetic portion 466 can be a flange that extends continuously over each of the plurality of stator cores 460 and connects them to yoke them together.

[0080] Thus, each stator core 460 defines a peripheral contact surface 480. Figure 8 and Fig. 9In the illustrated embodiment, a first portion 480A of the peripheral contact surface is defined by the magnetic material of the magnetic portion 466 corresponding to the at least one central protruding area 482. A second portion 480B of the peripheral contact surface 480 is defined by the electrically insulating material 470. As shown, the electrically insulating material 470 occupies the outward region or second portion 480B of the peripheral contact surface 480, while the SMC material in the magnetic portion 466 defines the central first portion 480A of the peripheral contact surface 480. The central first portion 480A of the peripheral contact surface 480 can be formed by the magnetic or ferromagnetic material of the magnetic portion 466, which can be an SMC material or a laminated magnetic steel layer as described above. As a non-limiting example, the laminated magnetic steel material can have a thermal conductivity greater than or equal to about 30 W / m·K to less than or equal to about 50 W / m·K. Therefore, the first portion 480A of the peripheral contact surface 480 has a higher thermal conductivity than the surrounding second portion 480B formed by the electrically insulating material 470. The stator 450 also includes a heat exchanger jacket 490, which is configured to circulate a heat transfer fluid or liquid within a plurality of built-in channels 492. The heat exchanger jacket 490 is circumferentially disposed around at least a portion of the periphery of the stator 450, more specifically around a portion of the plurality of stator cores 460. Thus, each peripheral contact surface 480 of each stator core 460 is in a heat transfer relationship and may be configured in some aspects to contact the heat exchanger jacket 490. As previously described, the SMC material or laminated magnetic steel in the magnetic portion 466 has a relatively high thermal conductivity. Therefore, the first portion 480A present in the peripheral contact surface 480 defined by the magnetic portion 466 has a greater thermal conductivity than the electrically insulating material 470, so that the heat transferred from the plurality of stator cores 460 to the heat exchanger jacket 490 is increased. Again, as a non-limiting example, heat transfer may be increased by at least ten times and in some aspects by several dozen times.

[0081] It should also be noted that Figure 8 and Fig. 9 The amount of magnetic leakage that occurs with the illustrated design is relatively very small, e.g., less than or equal to about 0.5% when calculating the total magnetic flux that occurs in the central protruding region of the magnetic portion 466 (which is adjacent to and extends through the conductive wire winding 464) relative to the overall magnetic flux of the magnetic portion / entire stator core 460. As discussed above, in certain variations, the material disposed in the at least one protruding region 482 of the magnetic portion 466 may have different properties than the central region of the core, such as a lesser density or a different composition with a different amount of magnetic components. In various aspects, the present disclosure thus provides stators for axial flux electric machines, including both yokeless and yoke-type stator designs, which enable heat-generating or magnetic portions of the stator to be in direct contact with a heat exchanger (e.g., a water jacket).

[0082] For the purpose of illustration and description, the above description of the embodiment has been provided. It is not intended to be exclusive or limit the present disclosure. Each element or feature of a particular embodiment is generally not limited to the particular embodiment, but is interchangeable and can be used for a selected embodiment where applicable, even if not specifically shown or described. It can also be changed in many ways. Such a variation should not be regarded as departing from the present disclosure, and all such modifications are intended to be included in the scope of the present disclosure.

Claims

1. A stator assembly for an axial flux motor, comprising: a heat exchanger jacket configured to circulate a heat transfer liquid; and A stator comprising a plurality of stator cores, each of the stator cores comprising: Conductive winding; an electrically insulating material disposed over at least a portion of the electrically conductive winding; and Molded soft magnetic composite (SMC) materials; wherein the heat exchanger jacket is circumferentially disposed around at least a portion of an outer periphery of the stator, wherein each stator core defines an outer peripheral surface configured to contact the heat exchanger jacket, and at least a portion of the outer peripheral surface is defined by the molded soft magnetic composite (SMC) material, wherein a first portion of the outer peripheral surface is defined by the molded soft magnetic composite (SMC) material, and a second portion of the outer peripheral surface is defined by the electrically insulating material, and Wherein the molded soft magnetic composite (SMC) material defines a region configured to receive the electrically conductive winding.

2. The stator assembly according to claim 1, wherein: The second portion is a central area of ​​the outer peripheral surface, and the first portion defines at least two outer areas of the outer peripheral surface, and the molded soft magnetic composite (SMC) material defines at least one central recessed area configured to receive the conductive winding, wherein the electrically insulating material is disposed on the conductive winding and the molded soft magnetic composite (SMC) material defines protruding flanges on both sides of the at least one central recessed area.

3. The stator assembly according to claim 1, wherein: The first portion is a central region of the outer peripheral surface, and the second portion defines at least two outer regions of the outer peripheral surface, and the molded soft magnetic composite (SMC) material extends between adjacent stator cores of the plurality of stator cores, and the stator has a yoke design.

4. The stator assembly according to claim 1, wherein: The outer peripheral surface is defined by a molded soft magnetic composite (SMC) material having a centrally disposed gap therein, and the molded soft magnetic composite (SMC) material defines a recess below the outer peripheral surface that receives the conductive winding and the electrically insulating material disposed therein.

5. The stator assembly according to claim 1, wherein: The plurality of stator cores are physically separated from each other, and the stator has a yokeless design.

6. The stator assembly according to claim 1, wherein: The molded soft magnetic composite (SMC) material has a strength of greater than or equal to about 7.4 kg / m 3 The first density of the molded soft magnetic composite (SMC) material is greater than or equal to about 7.0 kg / m at the outer peripheral surface. 3 To less than or equal to about 7.4kg / m 3 of the second density.

7. The stator assembly according to claim 1, wherein: The molded soft magnetic composite (SMC) material includes a plurality of magnetic particles including iron, and the electrically insulating material is selected from the group consisting of epoxy resin, glass, porcelain, silicone rubber, ethylene propylene diene monomer (EPDM), composite materials, and combinations thereof.

8. An axial flux motor, comprising: The stator assembly according to claim 1; as well as At least one rotor includes a plurality of magnets, and an air gap is defined between the stator and the at least one rotor.

9. A method of manufacturing a stator core component for an axial flux electric machine according to claim 8, comprising: introducing a soft magnetic composite (SMC) material precursor into a cavity of a mold comprising a first region and a second region, wherein the soft magnetic composite (SMC) material precursor comprises a polymer precursor and a plurality of magnetic or ferromagnetic particles; as well as compressing the soft magnetic composite (SMC) material precursor in the cavity by simultaneously applying a first pressure greater than or equal to about 800 MPa by a first pressure head in the first region and a second pressure greater than or equal to about 300 MPa to less than or equal to about 600 MPa by a second pressure head in the second region; as well as A consolidated soft magnetic composite (SMC) material component is removed from the cavity, the consolidated soft magnetic composite (SMC) material component having a first density corresponding to the first region where the first pressure is applied and a second density corresponding to the second region where the second pressure is applied.

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