Systems and methods for electromechanics

Abstract

The electromachine includes a rotor body defining the rotor axis, the rotor body including a back iron, a plurality of shanks extending radially away from the back iron, and a plurality of pole caps, each detachably coupled to a corresponding one of the plurality of shanks. The back iron, the shanks, and the pole caps can be made of different materials, and the rotor is capable of changing the flow of magnetic flux to vary the number of poles of the motor. A retaining wrap, pre-tensioned, is provided to help fix the rotor components together and to allow for increased rotor speed. A retainer is positioned between the rotor body and the retaining wrap to compensate for thermal expansion and to keep the retaining wrap within a predetermined tension range.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 467,512, filed on May 18, 2023; U.S. Provisional Patent Application No. 63 / 536,302, filed on September 1, 2023; and U.S. Provisional Patent Application No. 63 / 553,029, filed on February 13, 2024, each of which is hereby incorporated by reference in its entirety.

[0002] Reference to Research or Development by Government Support Not applicable.

Background Art

[0003] The present disclosure generally relates to systems and methods for an electromechanical machine, and more specifically, to arrangements and manufacturing methods for a rotor that can change the configuration of a rotor consisting of multiple materials, as well as a rotor holding system and magnetic poles.

Summary of the Invention

[0004] According to one aspect of the present disclosure, a rotor for an electromechanical machine is provided. The rotor can include a rotor body and rotor windings. The rotor body can define a rotor axis and a plurality of teeth extending radially away from the rotor axis. The rotor body can include a back iron, a plurality of shanks, and a plurality of magnetic pole caps. The plurality of shanks can extend radially away from the back iron, and each of the plurality of shanks can correspond to one of the plurality of teeth. The plurality of magnetic pole caps can be removably coupled to a corresponding one of the plurality of shanks. The rotor windings can be wound around the plurality of teeth.

[0005] In some cases, multiple pole caps can be made from a first material, and the back iron and one of the multiple shanks can be made from a second material different from the first material. In some cases, the first material may be electrical steel, and the second material may be carbon steel. In some cases, the back iron can be made from the second material, and the multiple shanks can be made from a third material.

[0006] In some cases, the back iron may have a first grain orientation, and the shanks may have a second grain orientation. In some cases, the first grain orientation is circumferential orientation with respect to the rotor axis, and the second grain orientation is radial orientation with respect to the rotor axis.

[0007] An electromachine is provided according to another aspect of the present disclosure. The electromachine may include a stator and a rotor configured to rotate relative to the stator. The rotor may include a rotor body, rotor windings, a retaining wrap, and a compliance member. The rotor body may define a plurality of teeth, and the rotor windings may be wound around the plurality of teeth. A retaining wrap may be wound around the rotor body and may be configured to apply a compressive force to hold the rotor windings on the rotor body. A compliance member may be configured to keep the retaining wrap within a predetermined tension range.

[0008] In yet another aspect of the present disclosure, an electromachine is provided in which the configuration of the magnetic poles can be changed. The electromachine may include a stator and a rotor configured to rotate relative to the stator. The rotor may include a plurality of rotor windings wound around a plurality of corresponding teeth extending from a rotor core. The rotor core may be made of a magnetizable material and may be configured to be selectively magnetized to a first magnetic pole configuration having a first number of magnetic poles and a second magnetic pole configuration having a second number of magnetic poles different from the first number of magnetic poles.

[0009] Another aspect of this disclosure provides a rotor assembly for an electromechanical device. The rotor assembly includes a rotor shaft including flanges positioned at its ends, a rotor body coupled to the rotor shaft, and rotor windings supported on the rotor body. The rotor assembly further includes a balance ring that holds the rotor windings on the rotor body. The balance ring defines an inner lip, and the flanges bend toward the inner lip to hold the rotor windings on the rotor shaft.

[0010] A more detailed description below will help to better understand the present invention and reveal features, embodiments, and advantages other than those described above. Such a detailed description is referenced in the following drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of an electromachine including a stator and rotor according to an aspect of the present disclosure. [Figure 2] Figure 1 is an exploded view of an electric motor. [Figure 3] This is a cross-sectional view of the first rotor configuration of the rotor shown in Figure 1. [Figure 4] This is a cross-sectional view of the second rotor configuration of the rotor shown in Figure 1. [Figure 5] This is a cross-sectional view of the third rotor configuration of the rotor shown in Figure 1. [Figure 6] This is a cross-sectional view of the fourth rotor configuration of the rotor shown in Figure 1. [Figure 7] This is a schematic diagram showing a portion of the path of magnetic flux passing through the rotor in Figure 1. [Figure 8] This is a cross-sectional view of a rotor in a first configuration having six rotor poles. [Figure 9] This is a cross-sectional view of the rotor in Figure 8 in a second configuration having two rotor poles. [Figure 10] This is a schematic diagram of a rotor in a first configuration having eight rotor poles. [Figure 11] This is a schematic diagram of the rotor in Figure 10 in a second configuration having four rotor magnetic poles. [Figure 12]Schematic diagram of the rotor in FIG. 10 in a third configuration having two rotor poles. [Figure 13] Perspective view of a portion of a bobbin-wound wire attached to a rotor including a circumferential retaining wrap. [Figure 14] Side view of a portion of a rotor having an axial retaining wrap. [Figure 15] Top view of a portion of the rotor in FIG. 14. [Figure 16] Schematic diagram showing the aspect of the rotor in FIG. 14. [Figure 17] Plot showing the stress in a pole cap fixed by a key. [Figure 18] Plot showing the stress in a pole cap not relying on a key. [Figure 19] Perspective view of a rotor winding fixed to a compliance member configured as a cooling can. [Figure 20] Cross-sectional view of a portion of a rotor tooth having a pole cap with an inclined inner surface. [Figure 21] Cross-sectional view of a rotor having a balance ring fixed by a rotor shaft. [Figure 22] Front isometric view of the rotor in FIG. 21 showing a balance ring fixed by a rotor shaft. [Figure 23] Rear isometric view of the rotor in FIG. 21 showing a balance ring fixed by a rotor shaft.

Embodiments for Carrying Out the Invention

[0012] Before the details of the embodiments of the present invention are described, it should be understood that the present invention is not limited to the configurations, arrangements of components, or forms shown in the following figures as described below. The present invention can have other embodiments and can be implemented or carried out in various ways. It should also be understood that the expressions and terms used in this specification are for the purpose of explanation and should not be construed restrictively. "Including", "comprising", "having" and their variants mean including the items listed below, their equivalents, and additional items. Unless otherwise specifically limited, "mounted", "connected", "supported", "coupled" and their variants are used in a broad sense and include both direct and indirect installation, connection, support, and coupling. Also, "connected" and "coupled" are not limited to physical or mechanical connection or coupling.

[0013] As used herein, the term "about" refers to variations in normal measurements and manufacturing procedures applicable to footwear and other manufactured products, including the embodiments described herein, accidental errors in these procedures, differences in the manufacturers, suppliers, and purity of the components used to create compositions and mixtures, and variations in numerical quantities caused by other similar factors. Throughout this disclosure, the terms "about" and "approximately" mean within a range of ±5% of the value shown before the numerical value.

[0014] The following description is provided to enable those skilled in the art to create and use embodiments of the present invention. Various modifications to the embodiments shown will be readily apparent to those skilled in the art, and the general principles of this specification are applicable to other embodiments and uses without departing from the embodiments of the present invention. Accordingly, embodiments of the present invention are not limited to those shown, and the broadest possible scope that does not contradict the principles and features disclosed herein should be given. The following detailed description should be considered with reference to the drawings, in which similar elements in different figures have the same reference numerals. The drawings are not necessarily to scale and show selected embodiments, and are not intended to limit the scope of embodiments of the present invention. Those skilled in the art will recognize that the examples presented herein have many useful alternatives that fall within the scope of embodiments of the present invention.

[0015] Electromechanics can be used to convert electrical energy into kinetic energy that can be used to perform work. In some electromechanics, such as electric motors or generators, the electromechanics include stationary components (e.g., stators) and rotating components (e.g., rotors). In an electric motor, an electric current is converted into an electromagnetic field, which exerts a mechanical force or torque between the stator and rotor, and this force or torque can be used to perform work. Generators operate on a similar principle to electric motors, but convert mechanical force into electric current. Although the description will mainly focus on rotational force or torque, the principles described herein are also applicable to linear motors. For example, in some linear motors, the rotor acts as a stationary component and the stator acts as a translational component.

[0016] An electromechanical rotor may include a rotor body that defines the rotor axis. The rotor body generally includes a back iron and a number of teeth extending radially from the back iron with respect to the motor axis. The teeth are configured to receive and hold windings, and the windings can be energized to generate a rotor magnetic field that interacts with the stator magnetic field to cause the rotor to rotate. More specifically, each tooth may include a shank extending from the back iron and a pole cap coupled to the distal end of the shank, and windings can be wound around the shank, with the pole cap configured to hold the windings on the rotor body during rotation.

[0017] In conventional designs, the rotor body may be fabricated from multiple punched or laser-cut sheets stacked together (e.g., axially) to form the rotor body. Each sheet is a monolithic structure formed from a single piece of material (e.g., electrical steel), meaning the rotor body is made from substantially a single material (although insulating layers may be placed between the sheets to help reduce eddy currents when dynamic magnetic fields are applied). Thus, each sheet forms the corresponding axial slice of the rotor body, including portions of the back iron and each of the multiple teeth (e.g., the shank and the pole caps). While the use of monolithic sheets simplifies the structure of the rotor body, it can also lead to performance losses because the rotor material must be selected according to the needs of specific regions (e.g., using electrical steel for the entire rotor body due to the rapidly changing magnetic flux in the pole caps), even though different regions of the rotor body face different levels or rates of magnetic flux change during normal operation.

[0018] Therefore, the specific design of a rotor may involve certain trade-offs, such as between the copper and steel regions in a given rotor diameter of a wound-field synchronous machine (WFSM). Generally, more copper allows the rotor to be more strongly excited at a given current density limit, resulting in greater torque / ampere, but the reduction in the steel region may lead to higher magnetic flux density and magnetic saturation of the rotor, as well as greater mechanical stress on the steel from centripetal acceleration. Thus, depending on the rotor design, high-performance motors may be limited to their maximum operating speed by rotational inertial stresses within the rotor, which increase with the square of the rotational speed, or by the tendency of soft, annealed copper windings to plastically deform outward at high speeds.

[0019] In some cases, to achieve improved performance (e.g., efficiency or torque output), WFSMs can incorporate permanent magnets or auxiliary rotors that can incorporate expensive, high-coercivity, low-permeability magnets (e.g., neodymium). However, these magnets can be oversized to compensate for performance degradation as the magnets warm up, with respect to peak torque conditions. Furthermore, the permanent magnetization state of these magnets is fixed and cannot be changed according to operating conditions. While induction motors can be manufactured robustly and inexpensively, they also have several drawbacks, including low power factor and efficiency under light load conditions, difficulty in speed control due to the machine being inherently a constant-speed machine, and relatively poor starting torque.

[0020] Accordingly, this disclosure provides alternative rotor structures and configurations that can achieve improved performance (e.g., peak torque, starting torque, efficiency, etc.) over a wide range of operating conditions compared to conventional rotor designs (with or without permanent magnets). For example, a rotor can be configured as a rotor body made of multiple materials, independent of conventional monolithic laminated sheets. Rather, various structures of the rotor body can be fabricated as separate components that can be coupled together to form the rotor body (e.g., laminated sheets or other construction methods), as generally described below.

[0021] To this end, each component of the rotor body can be fabricated from a material selected according to the electromagnetic requirements of that particular component. For example, the pole caps can be fabricated from a first material (e.g., a low-hysteresis and high-permeability material such as electrical steel) configured to match the rapidly changing magnetic field and transient magnetization that the pole caps face, while the rotor back iron or shank can be fabricated from a second material (e.g., a relatively high-hysteresis and low-permeability material such as carbon steel) configured to be magnetized or to have oriented crystal grains in order to control the magnetic flux passing through the rotor body between the rotor poles.

[0022] Figures 1 and 2 show non-limiting examples of the electromachine 100. The electromachine 100 can be configured as a wound-field synchronous motor including a stator 102 and a rotor 104 configured to rotate relative to the stator 102, but the principles described herein are also applicable to other types of electromachines. Generally as described above, current can be supplied to the windings in the stator 102 to generate a (rotating) stator magnetic field. Correspondingly, current can be applied to the windings in the rotor 104 to generate a rotor magnetic field that interacts with the stator magnetic field. More specifically, the stator magnetic field and the rotor magnetic field interact with each other, generating pushing and / or pulling forces on the rotor 104, causing the rotor 104 to rotate relative to the stator 102. The rotor 104 includes a rotor shaft 106 defining a rotor axis 108. The rotor 104 and stator 102 are aligned concentrically about the rotor axis 108, and the rotor 104 is detachably coupled to rotate in the internal cavity 110 of the stator 102 about the rotor axis 108. In some examples, the rotor 104 may further include one or more permanent magnets that contribute to the rotor magnetic field and also interact with the stator magnetic field to rotate the rotor 104.

[0023] As generally described below, a rotor can be constructed as a rotor made of multiple materials. A rotor made of multiple materials may include one or more distinct components that are joined together to form a single rotor made of multiple materials. Accordingly, the various components of a rotor made of multiple materials can be made from different types of materials, including, for example, steel (e.g., electrical steel, carbon steel, martensitic steel), aluminum, plastics, rubber, foamed plastics, and fiber-reinforced composite materials such as fiberglass or carbon fiber.

[0024] In some cases, the rotor may include a rotor body made of multiple materials configured to support the rotor windings. The rotor body can be configured in various ways to achieve desired performance characteristics, efficiency, etc. For this purpose, referring further to Figures 3 to 6, the rotor 104 (e.g., rotors 104A to 104D) generally includes a rotor core or rotor body 202. The rotor body 202 can be configured to receive a rotor shaft (e.g., rotor shaft 106). For example, the back iron 204 may define an opening 203 into which the rotor shaft 106 can be inserted so that the rotor body 202 can be coupled to the rotor shaft 106.

[0025] The rotor body 202 can support the rotor windings and includes a back iron 204 (e.g., defining an opening 203) and a plurality of teeth 208 extending radially away from the rotor axis 108 to support the rotor windings 214. In the non-limiting example shown, the rotor 104 includes six teeth, but other configurations may have a different number of teeth (e.g., two, four, eight, etc.). Each tooth 208 includes a shank 206 coupled to the back iron 204 and extending radially away from the back iron 204, and a pole cap 210 coupled to the radially distal end 212 of the shank 206. In other words, the rotor body 202 generally includes a plurality of shanks 206 and a plurality of pole caps 210 that collectively form a plurality of teeth 208.

[0026] Generally, as described above, the rotor teeth can be configured to receive and hold the rotor windings. As shown in Figures 3 to 6, the rotor 104 has rotor windings 214 wound around each tooth 208 (e.g., via a bobbin winding structure). More specifically, each winding 214 is wound around one of the shanks 206 and secured on the shank 206 by a pole cap 210. Thus, the shank 206 can have a chord length 216 shorter than the chord length 218 of the pole cap 210. The chord length is a dimension obtained perpendicular (e.g., tangentially) to both the radial and axial directions of the rotor. In this way, the pole cap 210 can define an overhang with respect to the corresponding shank 206, which can help hold the windings 214 on the rotor body 202 during rotation.

[0027] The rotor body's back iron, shank, and pole caps can be joined in various ways, for example, by direct mechanical coupling between adjacent components, indirect coupling via fastening systems, or integral formation with each other (e.g., as a monolithic substructure). Correspondingly, the coupling between two or more components may be permanent or removable. Furthermore, the back iron, shank, and pole caps can all be formed as laminated sheets or monolithically (e.g., as a single solid piece of material).

[0028] For example, in some cases, the back iron and multiple shanks can collectively define the rotor core. As shown in Figures 3 to 5, the shank 206 is formed integrally with the back iron 204 to form the rotor core 202. In this case, the rotor core 202 is formed as a laminate of multiple thin plates stacked along the axial direction. Correspondingly, each thin plate is formed as a monolithic plate including the corresponding back iron 204 and shank 206. Thus, each shank 206 extends radially away from the rotor axis 108, integrally with the back iron 204.

[0029] However, in some cases, the shank is formed separately from the back iron. For example, as shown in Figure 6, each shank 206 is formed separately from the back iron 204 and coupled to the back iron 204. More specifically, a mechanical meshing portion 220, configured here as a dovetail joint, is formed between each shank 206 and the back iron 204 to fix the shank 206 to the back iron 204. Furthermore, the back iron 204 can be configured as a segmented back iron having multiple back iron portions 222 coupled to each other (e.g., via mechanical meshing portions). In this case, each shank 206 is coupled to the corresponding back iron portion 222. In other non-limiting examples, a similar principle can be applied to other rotor components (e.g., shanks and pole caps) that can also be segmented.

[0030] Correspondingly, the pole caps can be formed as separate components attached to the shank (e.g., the rotor core). As shown in Figure 3, each pole cap 210 is configured as a separate component coupled to its respective shank 206. In this case, each pole cap 210 is coupled to one of the corresponding shanks 206 via a direct mechanical meshing connection 224. In particular, each shank 206 includes a projection 230 configured to be received in a socket 232 defined by the pole cap 210 (or vice versa). The projection 230 is located at the distal end of the shank 206 opposite to the proximal end of the shank 206 that couples with the back iron 204. The projection 230 and the socket 232 have complementary shapes and are configured to resist separation of the pole cap 210 from the shank 206 as a result of centripetal forces acting during rotation, by meshing together when the pole cap 210 is coupled to the shank 206. In the illustrated example, the projection 230 includes transverse flanges 229 on both sides extending from the body 231 of the projection 230 (e.g., extending circumferentially or substantially perpendicular to the radial direction). Each of the flanges 229 is received in an undercut 233 (e.g., a channel) defined in a recess 235 of the socket 232. The specific shapes of the projection 230 and the socket 232 may differ in other examples. In this way, the mechanical meshing connection 224 can function similarly to a dovetail connection and can also hold the winding 214 to the rotor body 202.

[0031] In other non-limiting examples, the pole caps can be held on the shank in other ways. In particular, the rotor may include a fastening system configured to secure the pole caps to the shank. For example, as shown in Figure 4, the pole cap 210 can be secured to the shank 206 by fasteners 234 (e.g., pins, threaded rods, nuts and bolts, etc.). More specifically, the shank 206 may define an opening 236 that can be aligned with a corresponding opening in the pole cap 210 so that the fasteners 234 can be inserted. In this way, the fasteners 234 can securely fasten the pole caps 210 to multiple shanks 206 by forming a pin connection between the projection 230 and the socket 232, and can hold the windings 214 to the rotor body 202. In another non-limiting example, as shown in Figure 5, the pole cap 210 can be secured to the shank 206 by retaining wraps 240. The retaining wrap 240 is generally configured to wrap around the outer circumference of the rotor core 202, applying radial compression between the magnetic pole cap 210 and the shank 206. Further details of the retaining wrap are described below.

[0032] Because the pole caps can be formed separately from the shank (i.e., the rotor core), windings can be attached to the rotor more easily compared to conventional rotor designs, thus enabling more compact windings and increasing efficiency and power density. More specifically, in conventional windings, the pole caps cannot be removed, and the windings must be wound in place around each rotor tooth (e.g., around the shank and below the pole caps). However, as shown in Figures 3 to 6, the pole caps 210 of rotors 104A to 104D are removable from the shank 206, so the windings 214 can be wound around the shank 206 before the pole caps 210 are fixed. Alternatively, because the pole caps 210 can be removed, it is also possible to receive pre-formed windings onto the shank 206.

[0033] More specifically, the pre-formed winding may be a bobbin-wound winding. Bobbin winding is the process of winding the winding (i.e., the wires constituting the winding) onto a separate bobbin before installation on the shank 206. The bobbin winding process allows for a higher copper slot filling coefficient (i.e., filling rate or filling percentage) because, in at least some examples, the slot can be completely filled without concern for the winding machine interfering with the geometric shape of the rotor core 202 (e.g., the magnetic pole cap or shank). Furthermore, this process also allows for the compression of the winding before assembly into the shank 206, which can be difficult, if not impossible, in conventional rotor designs where in-situ winding is required. Thus, bobbin-wound and compressed winding can achieve a slot copper filling coefficient of about 70%, whereas in-situ winding typically only achieves a filling percentage of about 50% to 60%. This increase in winding density allows for higher winding densities, resulting in electromechanics with higher power density and efficiency. Furthermore, since bobbin winding can be done separately from rotor assembly, assembly can be easily parallelized during manufacturing and assembly, leading to reduced cycle times, which is not possible with in-situ winding.

[0034] The formation of integral yet distinct components allows for the use of different materials in different areas of the rotor. For example, electrical steel can be selectively used in areas exposed to strong or rapidly changing magnetic fields (e.g., the air gap between the rotor and stator, or its vicinity, such as the pole caps). Electrical steel typically has a high silicon content (e.g., up to about 6.5% silicon, or more specifically, about 1% to about 3%, about 2% to 5%, or about 3% to about 6.5%, or any range within these), resulting in high electrical resistivity and thus reduced eddy currents and associated losses (e.g., core losses in the rotor core). Furthermore, electrical steel typically has a low carbon content (e.g., less than 0.05% carbon, or more specifically, less than about 0.01% carbon, or less than about 0.005% carbon, or any range within these), thus reducing hysteresis losses and increasing permeability.

[0035] As mentioned above, electrical steel can reduce eddy currents and losses due to rapid changes in magnetic flux. Therefore, in some examples, the entire rotor core can be made of electrical steel. However, since rapid changes in magnetic flux may be more common in certain regions of the rotor core, in some examples, electrical steel is used in those regions of the rotor core, while other materials are used in regions where the changes in magnetic flux may not be as rapid. For example, as shown in Figure 7, this rapid change in magnetic flux 250 is governed by the passage of the stator teeth / slots and is typically limited to a region very close to the air gap 252 between the rotor 104 and the stator 102 (e.g., within the pole cap 210), so the majority of the rotor magnetic flux is nearly constant (e.g., in the shank 206 and back iron 204). Therefore, carbon steel can be used in rotor cores where the magnetic flux is largely constant, or where selective magnetization may be useful to improve rotor performance depending on the operating conditions (e.g., in the shank and back iron). Carbon steel typically has a higher carbon content (e.g., between approximately 0.4% and 4%, between approximately 0.4% and 2%, between approximately 2% and 4%, between approximately 1% and 3%, or any range between approximately 0.4% and 4%) and is generally less expensive than electrical steel. Therefore, by selectively combining electrical steel and carbon steel in specific configurations, it is possible to manufacture rotor bodies that are more efficient and have higher power density compared to conventional rotor structures.

[0036] For example, as shown in Figures 3-5 and 7, the rotor core 202 can be formed collectively, and the shank 206 and back iron 204, located away from the gap 252, can be formed from carbon steel (e.g., as a laminate of thin sheets). The back iron 204 and shank 206 provide a relatively long arc length 251 to the magnetic flux 250, and can induce a large magnetomotive force (MMF) even with the low coercivity achievable from carbon steel. Correspondingly, the pole cap 210, positioned directly adjacent to the gap 252 (e.g., between the rotor core 202 and the gap 252), can be formed from electrical steel (e.g., as a laminate of thin sheets) because it tends to experience larger changes in magnetic flux than the shank 206 and back iron 204 during operation, and the arc length 253 of the magnetic flux 250 tends to be shorter.

[0037] In addition to providing optimal or purpose-specific material use that helps improve motor performance and efficiency, using carbon steel in the rotor core can further improve performance by allowing the rotor's magnetic flux to be changed and the number of rotor poles (i.e., the rotor's magnetic poles) to be changed. That is, as generally described above, carbon steel can be selectively magnetized and demagnetized, so that the configuration of the number of poles can be changed during motor operation (on the fly). Thus, a multi-material rotor, as in some examples of this disclosure, can selectively change the magnetic flux to multiple pole configurations having various numbers of poles that may differ from the number of teeth. This possibility of configuration change is in contrast to a rotor core that uses only electromagnetic steel, which generally does not allow for a change in magnetic flux and has a fixed number of poles equal to the number of rotor teeth.

[0038] To control the possibility of configuration changes, the motor may include a controller that can be configured to switch between a first pole configuration and a second pole configuration based on the operating parameters of the electromechanical unit (e.g., speed command or output, torque command or output, operating temperature, etc.). In some cases, the controller can change the magnetic flux of the rotor by controlling the energization of the stator windings. For example, the stator may include stator windings, and the controller may be configured to control the flow of current through the stator windings to induce a current corresponding to the rotor core, thereby switching the rotor core between a first pole configuration and a second pole configuration.

[0039] In response to this, the magnetic flux of the rotor can be modified to have a specific number of poles that can be selected according to the rotor's operating parameters or state (e.g., rotational speed, torque output, etc.) or the vehicle's operating parameters or state (e.g., vehicle speed, driving mode, towing / carrying mode, incline, commanded acceleration, etc.). For this purpose, different numbers of rotor poles can provide improved performance under different operating conditions. In particular, a larger number of poles generally generates greater torque, which can be especially useful at low speeds (e.g., low vehicle speed, rotor rotational speed), during periods of strong acceleration, or when towing or carrying loads uphill. However, at high speeds, a larger number of poles typically causes a large reverse EMF current in the stator, potentially limiting the maximum achievable speed, increasing temperature, or degrading motor performance. Conversely, a smaller number of poles is generally advantageous for low-torque, high-speed operation, such as that common during highway driving. This is because a smaller number of poles typically results in relatively less reverse EMF current in the stator, making it possible to achieve high speeds while maintaining high motor efficiency.

[0040] Generally, a rotor has an even number of poles such that each north pole has a corresponding south pole. For example, Figures 8 and 9 show a rotor 104 having six teeth 208 that can change the magnetic flux to two configurations. In the first configuration shown in Figure 8 (for example, a high-torque or low-speed configuration, such as above half of the rated torque or below half of the rated motor speed), the magnetic flux of the rotor 104 is changed to have a first number of poles consisting of six rotor poles. In the first configuration, each tooth 208 defines either a north pole 260 or a south pole 262, and the polarities of adjacent shanks 206 are opposite to each other. In other words, the polarity of the teeth 208 is in an alternating pattern, resulting in a total of three north poles and three south poles, each north pole having a south pole corresponding to the radially opposite side of the rotor 104. Therefore, because opposite polarities attract each other and similar polarities repel each other, the magnetic flux 264 of one tooth extends to each of the immediately adjacent teeth that have the opposite polarity.

[0041] However, in the second configuration shown in Figure 9 (for example, a low-torque or high-speed configuration, such as below half the rated torque or above half the rated motor speed), the magnetic flux of the rotor 104 can be modified to have a second, different number of poles consisting of two poles. In the second configuration, teeth having similar polarity are grouped together to form a first pole 260 in the first half of the rotor (for example, a first semi-cylindrical region of the rotor containing three adjacent teeth 208) and a second pole 262 in the corresponding second half of the rotor (for example, a second semi-cylindrical region of the rotor containing three adjacent teeth 208). Here, the first pole 260 contains three adjacent teeth 208, each having N polarity, and the second pole 262 also contains three adjacent teeth 208, each having S polarity. Thus, the magnetic flux 264 passing through the rotor 104 in this configuration generally extends from the second pole 262 to the first pole 260.

[0042] Alternatively, as a non-limiting example, Figures 10–12 show a rotor 104 having eight teeth 208 that can be reconfigured into three different configurations. In the first configuration shown in Figure 10 (for example, a high-torque or low-speed configuration, such as exceeding two-thirds of the rated torque or falling below one-third of the rated motor speed), the magnetic flux of the rotor 104 is modified to have a first number of poles consisting of eight rotor poles, such that each tooth 208 defines either an N pole 260 or an S pole 262, and the polarities of adjacent shanks 206 are different from each other. In other words, the polarity of the teeth 208 is in an alternating pattern, resulting in a total of four N poles and four S poles, with each N pole having a corresponding S pole on the radially opposite side of the rotor 104.

[0043] In the second configuration shown in Figure 11 (for example, a medium torque or medium speed configuration, such as between one-third and two-thirds of the rotor torque or motor speed), the magnetic flux of the rotor 104 is modified to have a second number of poles consisting of four poles. In the second configuration, two adjacent teeth are grouped together to form poles in each quadrant of the rotor 104. More specifically, the rotor 104 has a first quadrant defining a first N pole 260, a second quadrant defining a first S pole 262, a third quadrant defining a second N pole 260, and a fourth quadrant defining a second S pole 262, arranged in an alternating pattern around the rotor 104. Therefore, the magnetic flux 264 passing through the rotor 104 of the second configuration generally extends from one tooth to each directly adjacent tooth (i.e., from the tooth directly adjacent to one of the S poles 262 to the tooth directly adjacent to one of the N poles 260) such that the magnetic flux entering the S pole is divided to each of the two adjacent N poles. For example, the magnetic flux entering the first tooth of the S pole generally goes toward the first N pole, and the magnetic flux entering the second tooth of the S pole generally goes toward the second N pole opposite the first N pole.

[0044] In the third configuration shown in Figure 12 (for example, a low-torque or high-speed configuration, such as below one-third of the rated torque or above two-thirds of the rated motor speed), the magnetic flux of the rotor 104 is modified to have a third number of poles consisting of two poles. Similar to Figure 9, in the third configuration, teeth 208 having similar polarity are grouped together to form a first pole 260 in the first half of the rotor (e.g., the first semi-cylindrical region of the rotor) and a second pole 262 in the corresponding second half of the rotor (e.g., the second semi-cylindrical region of the rotor). Here, the first pole 260 is defined by four adjacent teeth 208, and the remaining four adjacent teeth 208 define the second pole 262. Thus, the magnetic flux 264 passing through the rotor 104 in the third configuration generally extends from the second pole 262 to the first pole 260.

[0045] In some cases, motor performance can be improved in other ways by using different material arrangements in the rotor. In particular, oriented steel (GOES) and non-oriented steel (NGOES) can be used in different regions of the rotor depending on (for example, to approximate) the optimal or intended magnetic flux path through the rotor. NGOES has magnetic crystal grains in the steel that are randomly oriented and do not provide a preferred or optimal direction for magnetic flux. Therefore, magnetic flux in a particular direction through the rotor core is neither particularly supported nor hindered by the crystal grains, and NGOES has a nearly neutral effect on magnetic flux. Thus, NGOES can improve the efficiency of rotor operation when magnetic flux lines are not sufficiently aligned in a single direction (e.g., at magnetic pole caps) or are spread out.

[0046] In contrast to NGOES, the magnetic crystal grains of GOES are aligned in a specific direction, resulting in magnetic properties aligned to a desirable orientation (for example, to increase permeability along a particular direction). The orientation of the crystal grains can enable more efficient operation of the rotor by helping to guide the magnetic flux along a desired path through the rotor. Furthermore, GOES can increase the magnetic flux density in the rotor by approximately 30% compared to NGOES, for example. However, because the crystal grains are oriented along a specific direction, GOES may exhibit greater losses if the magnetic flux does not move along the direction of the crystal grains. Therefore, GOES can be advantageously used when the direction of the magnetic flux is nearly constant along a known direction, such as in the shank and back iron.

[0047] Some rotor cores may include monolithic structures consisting entirely of NGOES or entirely of GOES. However, in some examples, the rotor may have a combination of GOES and NGOES, each positioned at specific locations on the rotor core, to enable more efficient operation of the rotor. For example, the rotor core may include NGOES in locations where the magnetic flux lines do not need to be well aligned in a single direction (e.g., the pole caps) or where the density may be low. Furthermore, the rotor core may include GOES in locations where the magnetic flux lines are aligned or have a relatively high density, such as the shank and back iron. Such combinations can obtain the advantages of both GOES and NGOES and avoid embodiments of GOES and NGOES that may reduce or limit efficiency.

[0048] For example, referring to Figures 6 and 7, grain orientation can substantially align the magnetic properties of the material with the magnetic flux lines, increasing the magnetic flux density, enabling higher torque at a given current density limit, or allowing for a reduction in rotor core area and an increase in copper region (e.g., winding region), thereby reducing the required current density. For example, Figure 7 shows that the magnetic flux lines 250 typically extend between the back iron 204 and the pole cap 210 in a direction substantially perpendicular to the length 216 of the shank 206 (e.g., circumferential and / or radial with respect to the rotor axis 108). Thus, as shown in Figure 6, the shank 206 can have a first grain orientation 268 along a first direction (e.g., radial with respect to the rotor axis 108) so as to be substantially parallel to the optimal magnetic flux path within the shank 206. Similarly, the magnetic flux lines typically extend along the circumferential or tangential direction within the back iron 204. Therefore, each back iron portion 222 can have a second grain orientation 270 that is substantially circumferential or tangential with respect to the rotor axis 108. In this way, the back iron portions 222 can collectively approximate the circumferential grain orientation in the back iron 204. Correspondingly, the grain orientations of the back iron portions 222 and the shank 206 can be substantially perpendicular to each other.

[0049] As mentioned above, in some cases, retaining wraps can be used to help secure rotor components to each other, thereby enabling multi-material rotors to operate at higher speeds (e.g., over approximately 15,000 revolutions per minute). Retaining wraps may be thin compared to the radial direction of the rotor (e.g., approximately 0.2 mm to 5 mm, 0.2 mm to 1 mm, 0.2 mm to 2 mm, or 0.2 mm to 3 mm depending on specific operating conditions) to minimize their impact on air gaps and therefore on electromagnetic performance. However, thicker wraps can also typically apply greater force to the rotor (e.g., in a given material of the wrap), enabling higher speeds and, in some cases, reducing the need for key connections between rotor components. In some cases, retaining wraps are made of composite materials, such as carbon fiber composites, or more specifically, uniaxial epoxy-carbon composites, due to their high strength-to-weight ratio. Correspondingly, the wrapping configuration of retaining wraps on the rotor can be optimized or selected to provide the necessary reinforcement capabilities required for individual applications while minimizing weight.

[0050] For example, as shown in Figure 13, in some applications, the retaining wrap 240 can be configured as a circumferential retaining band that may be wrapped around part or all of the axial length of the rotor 104. The circumferential configuration allows the retaining wrap 240 to apply radial compressive force to both the windings 214 and the rotor body 202 (e.g., at the pole caps 210). Correspondingly, the retaining wrap 240 can also counteract the centripetal force that the rotor components experience during rotation. In other non-limiting examples, two or more retaining wraps can be used and positioned at any location along the axial length of the rotor 104.

[0051] In some examples, the rotor 104 may include a retainer 242 positioned between the retaining wrap 240 and the winding 214 so that the retaining wrap 240 can be forcefully applied by the winding 214 (see also Figures 3, 5, and 6). More specifically, the retainer 242 may be positioned within the winding channels between each pair of teeth 208 and may span the gap between the pole tips. Due to the circumferential retaining wrap, the design may have a larger air gap between the rotor 104 and the stator 102 to accommodate the thickness of the retaining wrap. Thus, in some examples, to help reduce the air gap, the rotor 104 may define a channel 244 (e.g., a localized area of ​​the rotor body 202 or a reduced circumference) and the retaining wrap 240 may be placed within the channel 244. As a result, the rotor lamellae around which the retaining wrap 240 is wound may have a smaller diameter to accommodate the presence of the retaining wrap 240, while the rotor lamellae not wound may have a larger diameter. This combination can result in both a smaller air gap and improved electromagnetic performance of the electromechanical unit 100.

[0052] In other examples, as shown in Figures 14 and 15, the retaining wrap 240 can be configured as an axial retaining band. That is, the retaining wrap 240 can be wrapped around two teeth and around each end of the rotor such that the wrap extends axially (for example, perpendicular to the circumferential direction) along the length of the teeth 208. The axial portion of the retaining wrap 240 may be received in the winding channel between the teeth 208 and extend along the winding channel. In this way, the overall diameter can be reduced to minimize the air gap between the rotor 104 and the stator 102. Correspondingly, a retainer 242 can be placed between the retaining wrap 240 and the winding 214, similar to the circumferential wrapping in Figure 13 (see Figure 16). In some examples, to assist in the transmission of radial forces to the winding 214, the retainer 242 has an outer surface 246 with a crown.

[0053] When using an axial wrapping configuration, the rotor may include multiple axial retaining wraps 240. As best shown in Figure 15, the rotor 104 includes six axial retaining wraps 240A–240F. The wraps 240A–240F are arranged in a star pattern, with each tooth 208 directly wrapped together with each adjacent tooth. In other words, the retaining wraps 240 cross the ends of the rotor 104, along the winding channel, and span two adjacent teeth. The retaining wraps 240 may be arranged in other ways in other examples.

[0054] Relatedly, since axial wrapping results in a retaining wrap 240 extending around the end of the rotor 104, a cap 248 can be provided at the end of the rotor 104. In some cases, the cap 248 can be configured as a molded or 3D printed cap formed from plastic, composite material (e.g., fiberglass, carbon fiber, etc.), steel, aluminum, or other material. In some cases, the cap 248 can be configured as an end plate for bolting or clamping the rotor (e.g., to apply axial compression to the rotor 104) and for rotational balancing of the rotor 104. The cap 248 can help guide, support, and secure the retaining wrap 240 between the winding channels. Furthermore, the cap 248 can also help guide, support, and secure the windings 214 between the winding channels (see, for example, Figure 16). In some cases, the cap 248 can also function similarly to a retainer by ensuring the maintenance of proper tension on the rotor 104.

[0055] In some cases, the retaining wrap can be pre-tensioned to apply a predetermined compressive force to the rotor (for example, when the rotor is not rotating). For example, by wrapping the retaining wrap under tension to apply a radial compressive force to the rotor, a compressive preload can be applied to the rotor, and thus, contact between the various components is maintained under rotational inertia loads that exhibit a "reloading" of this preload. The specific preload may be in the range of about 10% to about 50% or about 20% to about 30% of the ultimate strain of the retaining wrap material. In this way, the retaining wrap can maintain compression on the rotor components despite centripetal forces acting to reduce the pre-tension load during rotation.

[0056] Furthermore, the compression applied to the rotor can reduce stress on rotor components (e.g., the pole caps) during operation, enabling a greater maximum rotational speed (e.g., achieving speeds more than twice as high as a rotor without pre-tensioned wraps). For example, Figure 17 shows the stress present in a key-fixed pole cap during rotor rotation. By applying a preload with retaining wraps, the stress within the pole cap can be reduced, enabling higher rotational speeds. Furthermore, referring to Figure 18, if the preload is large enough that keying of the pole cap is unnecessary, the stress within the pole cap can be reduced even further, enabling even higher speeds. In any case, a specific pretension can be selected so that the stress within the pole cap does not exceed the yield strength of the pole cap material.

[0057] In some cases, the preload of a retaining wrap can be achieved with lower tensions to simplify the manufacturing process. That is, the total preload required for a retaining wrap to hold copper windings, magnetic pole caps, and retainers can be thousands to tens of thousands of Newtons, depending on the size of the machine and the intended speed. Wrapping the entire wrap with this total preload tension can be difficult and require larger, more robust machinery. However, it is possible to perform the wrapping process with lower tensions, at least partially, instead. In particular, the required wrapping tension can be reduced while maintaining the overall compressive force of the wrap by wrapping the uncured uniaxial fiber composite material (i.e., the fibers that form the retaining wrap) in small amounts in multiple layers at a time. For example, a circumferential wrap requiring a 4,000-pound preload can be wrapped in two 20-segment layers with only 100 pounds of tension. Wrapping can even be done a few fibers or strands at a time, reducing the required wrapping tension to just a few Newtons.

[0058] The rotor wrapping can be started with very low tension, and as the wrapping length increases, the friction from the entire wrapping length up to that point supports the increasingly larger wrapping tension until the target tension is reached. Similarly, the tension can be gradually reduced at the end of the wrapping process. This reduces the need to secure the ends of the wrap with high tension (e.g., using fasteners). The wrap can then be cured to form a pre-tensioned monolithic uniaxial composite band. In some cases, the ends of the wrap can also be wrapped to reinforce the radial support of the end windings.

[0059] The pre-tension of the retaining wrap allows a rotor wrapped in composite material to achieve significantly higher speeds than an equivalent rotor without the wrap; however, the different materials of the retaining band and rotor typically have different coefficients of thermal expansion. For example, the coefficient of thermal expansion of steel may be greater than that of the fiber-reinforced composite material (e.g., epoxy carbon) that makes up the retaining wrap. More specifically, the steel in the rotor may have a positive coefficient of thermal expansion, while the retaining wrap may have a negative coefficient of thermal expansion. As a result, for example, as the temperature rises during motor operation, the rotor may expand while the retaining wrap may contract. This difference in thermal expansion / contraction between the rotor steel and the retaining wrap can, in some cases, generate additional stress as the temperature rises.

[0060] To help compensate for the difference in thermal expansion / contraction between the rotor steel and the retaining wrap, the rotor may further include a compliance member. The compliance member can be positioned between the rotor body and the retaining wrap and can be configured to deform flexibly to reduce the stress caused by the difference in thermal expansion. Specifically, the compliance member can allow the rotor body and retaining wrap to change shape with temperature without substantially changing the overall outer diameter of the rotor. Thus, the compliance member allows the rotor body to change shape with temperature when the steel expands while the band does not expand (almost), thus avoiding an increase in stress on the band by allowing the outer diameter of the rotor body across the pole caps to increase, while the overall length of the bands remains almost unchanged. This allows for further room in the bands with respect to pre-tension, thinner bands, higher speeds, or any combination thereof. Furthermore, the nearly constant outer diameter of the rotor allows the retaining wrap to apply a desired amount of inward radial force to the rotor (e.g., the pole caps and windings), continuing to mitigate the tendency for gaps to open between separate parts of the rotor body under rotational inertia loads. The ability of a compliance member to compensate for the different expansions and contractions of rotor components can be derived from the material properties or geometric structure of the compliance member.

[0061] In some embodiments, compliance members can be configured to contract and / or expand during operation to maintain tension in the retaining wrap during operation. For example, during operation, heat and centripetal forces may cause expansion of the rotor and contraction of the retaining wrap 240, which may result in increased tension, and therefore increased force and stress on the rotor components. However, in other examples, it is conceivable that the rotor and retaining members may have different coefficients of thermal expansion so that heat and centripetal forces can cause expansion of the retaining wrap 240. This may result in decreased tension, and therefore reduced force on the rotor components. To counteract this expansion and maintain a (minimum) predetermined tension in the tension wrap 240, compliance members 280 may also expand, as shown in Figures 5 and 13. In this regard, compliance members 280 may instead be configured as elastic members that can be preloaded by the tension wrap 240. When centripetal forces cause expansion of the tension wrap 242, compliance members 280 may expand due to the reduction in load, thereby absorbing the expansion of the retaining wrap 240 and ensuring that the rotor is subjected to appropriate tension. In some cases, the compliance member 280 may undergo thermal expansion due to temperature rise. This thermal expansion may be sufficient to absorb the expansion of the retaining wrap 240 by expanding the compliance member 280, thereby ensuring that the rotor is subjected to appropriate tension. In this regard, although only a single retaining wrap is shown, it is understood that multiple retaining wraps may be used.

[0062] In some cases, the compliance member can be positioned within the winding channel so as to be located between the retaining wrap and the coil. For example, as shown in Figures 5 and 13, the compliance member 280 can be positioned within the winding channel between the retaining wrap 240 and the winding 214. More specifically, the compliance member 280 can be positioned between the retainer 242 and the winding 214 so that the compressive force from the retaining wrap 240 is distributed more evenly along the compliance member 280.

[0063] The compliance member and retainer can be combined to form a retainer. For this purpose, the compliance member and retainer can also be formed as a single retainer. For example, as shown in Figure 3, the retainer 282 is positioned between the retaining wrap 240 and the winding 214. Specifically, the retainer 282 is shaped to function as both the compliance member 280 and the retainer 242. In particular, the arched outer surface can add rigidity to the retainer 282 so that it functions similarly to the retainer 242, while the substantially flat inner surface can provide compliance so that it functions similarly to the compliance member 280.

[0064] In some cases, the compliance member can also be configured to provide cooling to the rotor. For example, referring to Figure 19, in some cases the compliance member 280 can enclose the winding 214. In this way, the compliance member 280 can also function as a cooler can 284 for containing and controlling the flow of coolant around the winding 214. Correspondingly, end caps 248 can be used to form either a sealed enclosure or plenum around the ends of the rotor windings, or multiple enclosures around the individual coil ends, through which a coolant (e.g., ATF oil) can be injected to absorb and remove waste heat from the windings.

[0065] Alternatively, the coolant can be flowed axially along the length of the rotor between the winding and the rotor core within an insulated cooler formed by the compliance member 280. For this purpose, the use of bobbin windings and removable pole caps can enable the use of axial coolers, since axial coolers are difficult to manufacture in situ on the rotor. Accordingly, according to this disclosure, the cooler can be fixed around the bobbin windings prior to their assembly onto the shanks.

[0066] Furthermore, the use of a cooler can enable more than twice the current density, resulting in higher power, torque, and efficiency. Correspondingly, the rotor can be shaped to allow for a higher winding packing density, whether or not it includes a cooler can. More specifically, it may be beneficial to shape the pole cap to have inwardly sloping protruding tips. The protruding tips allow the pole cap to hold the rotor windings and the retainer used to hold the rotor windings in place, and also reduce the stress caused by the rotor windings and retainer.

[0067] Referring in particular to Figure 20, the pole cap 210 typically includes a protruding tip 274 that extends roughly circumferentially away from the shank 206. The tip 274 defines a radial inner surface 276 that engages with the winding 214. The inner surface 276 can be inclined radially at an angle 278 that can be selected depending on the cross-sectional shape of the wires constituting the winding 214. For circular wires, the angle 278 may be acute radially, for example, about 50 to about 70 degrees radially, more specifically about 60 degrees. In addition to allowing for higher density windings, the angle 278 can also reduce the vertical force applied to the pole cap 210 during rotation, reduce material stress, and allow for higher rotational speeds.

[0068] As described above, retaining wraps can be used to fix rotor components to each other in order to facilitate rotor operation at higher speeds. Specifically, retaining wraps can be used to counteract the centripetal force acting on the rotor components during rotation and thus ensure that the various components remain in contact under rotational inertia loads. In connection with this, caps (e.g., end caps) can be used to further enhance the structural integrity of the rotor by providing axial compression to the rotor with respect to the rotor axis defined by the rotor shaft. Furthermore, balance rings can be provided to cover the end caps, and the rotor shaft can define flanges for compressing the balance rings at each axial end of the rotor, thereby fixing the rotor components to each other and further maintaining contact under rotational inertia loads.

[0069] Referring here to Figure 21, a cross-sectional view of the rotor 104 is shown, which may include rotor windings 214 that may be fixed within the retainer 242. Furthermore, the cap 248 can be configured as an end plate for bolting or clamping the rotor 104 to apply axial compression to the rotor 104, as described above. Another rotor component, such as a balance ring, can be used to fix the cap to the axial end of the rotor to help minimize rotational imbalance of the rotor. For example, the cap 248 can be coupled to the retainer 242, as shown in the non-limiting example. To help fix the cap 248 to the retainer 242, a first balance ring 286 can be positioned over each cap 248. That is, the first balance ring 286 can be set over the cap 248, fixing the cap 248 and the rotor windings 214 between the first balance ring 286 and the retainer 242. In some cases, the retainer 242 can be configured to prevent the first balance ring 286 from rotating relative to the rest of the rotor 104 during operation (for example, to ensure that all rotor components rotate together).

[0070] Furthermore, in some examples, the second balance ring 288 can be positioned to at least partially cover one or both of the first balance rings 286, thereby fixing the first balance ring 286 between the cap 248 and the second balance ring 288. In particular, the second balance ring 288 can be bent or folded over the first balance ring 286 to fix the first balance ring 286 to the rotor 104 (e.g., by a roll forming process). For example, the outer rim 290 of the second balance ring 288 can be bent or folded over the radially inner lip 292 of the first balance ring 286. In this way, the second balance ring 288 can provide axial compression to the rotor 104 and function as a retaining structure that fixes the first balance ring 286 to the rotor 104. In some examples, the second balance ring 288 can define a diameter smaller than the diameter of the first balance ring 286, and the second balance ring 288 can be positioned concentrically with respect to the first balance ring 286. In the non-restrictive example, only one second balance ring is shown, but it should be understood that multiple second balance rings (for example, second balance rings positioned at each axial end of the rotor) may be used.

[0071] Thus, according to aspects of the present disclosure, the balance rings can be fixed without using separate fasteners as typically used in conventional rotor structures. In some examples, referring to Figures 21 to 23, a first balance ring 286 and / or a second balance ring 288 can be fixed to the rotor 104 via a rotor shaft 106. More specifically, the rotor shaft 106 may include flanges 294 at each end. The flanges 294 can be bent or folded into the balance rings 286 and 288 to fix the balance rings 286 and 288 to the rotor 104 (for example, by a roll forming process). For example, the flange 294 can be bent or folded into the radially inner lip 292 of the first balance ring 286, and / or the flange 294 can be bent or folded into the base 296 of the second balance ring 288 (i.e., the base 296 is integral with the outer rim 290 and positioned radially inward relative to the outer rim 290). In this way, the flange 294 can function as a retaining structure that provides axial compression to the rotor 104. In particular, the flange 294 can provide axial compression to the back iron portion 204, the rotor windings 214, the retainer 242, the end caps 248, the first balance ring 286, and / or the second balance ring 288. By configuring the rotor 104 in this manner, the complexity of the rotor can be reduced while increasing its structural integrity. For example, the balance rings 286, 288 and the end caps 248 can provide mechanical support to the rotor windings 214 over a variety of rotor speeds, either individually or in combination.

[0072] As described above, the rotor can be used in combination with a cooling device. When used in the claims, the phrase "at least one of A, B, and C" means at least one A, at least one B, and / or at least one C, or any one of A, B, or C, or a combination of A, B, or C. A, B, and C are components of the list, and A, B, and C may be anything included herein.

[0073] While the present invention has been described in relation to one or more specific embodiments, it should be understood that numerous equivalents, substitutes, variations, and modifications are possible and fall within the scope of the invention, in addition to those explicitly stated.

[0074] Further Examples

[0075] Example 1: A rotor for an electromachine, comprising: a rotor body defining a rotor axis and a plurality of teeth extending radially away from the rotor axis; a back iron; a plurality of shanks extending radially away from the back iron, each corresponding to one of the plurality of teeth; and a plurality of pole caps, each detachably coupled to one of the corresponding shanks; and a rotor winding wound around the plurality of teeth.

[0076] Example 2: The rotor according to Example 1, wherein the multiple pole caps are made of a first material, and at least one of the back iron and multiple shanks is made of a second material different from the first material.

[0077] Example 3: The rotor according to Example 2, wherein the first material is electrical steel and the second material is carbon steel.

[0078] Example 4: The rotor according to Example 2 or 3, wherein the back iron is made of a second material and the multiple shanks are made of a third material.

[0079] Example 5: The rotor according to Example 4, wherein the second material is a first electrical steel having a first grain orientation, and the third material is a second electrical steel having a second grain orientation.

[0080] Example 6: The rotor according to Example 5, wherein the first grain orientation is circumferential with respect to the rotor axis, and the second grain orientation is radial with respect to the rotor axis.

[0081] Example 7: The rotor according to Examples 1 to 6, wherein the rotor body includes a laminate of thin plates formed by stacking multiple thin plates along the rotor axis.

[0082] Example 8: The rotor according to Example 7, wherein each of the multiple sheets is a monolithic sheet forming both the back iron and the multiple shanks.

[0083] Example 9: The rotor according to Example 7 or 8, wherein the plurality of plates include a plurality of back iron plates that collectively form a back iron and a plurality of shank plates that collectively form a shank.

[0084] Example 10: The rotor according to Examples 7 to 9, further comprising a first end cap and a second end cap positioned at both ends of the rotor body, which provide clamping force to multiple thin plates and hold the rotor windings on the rotor body.

[0085] Example 11: The rotor according to Example 10, wherein each of the first end cap and the second end cap is made from at least one of a polymer material and a composite material.

[0086] Example 12: The rotor according to Examples 1 to 11, wherein multiple magnetic pole caps are held on the rotor body by retaining wraps.

[0087] Example 13: The rotor according to Examples 1 to 12, wherein each of the multiple pole caps is coupled to a corresponding one of the multiple shanks by a coupling with a lock and key.

[0088] Example 14: The rotor according to Examples 1-13, wherein each of the multiple pole caps is coupled to a corresponding one of the multiple shanks by a fastener.

[0089] Example 15: The rotor according to Examples 1-14, wherein each of the multiple shanks is connected to the back iron by a lock-and-key joint.

[0090] Example 16: The rotor according to Examples 1 to 15, wherein the back iron comprises a plurality of back iron portions, each of which is configured to be coupled to a corresponding one of a plurality of shanks.

[0091] Example 17: An electromachine comprising a stator and a rotor configured to rotate relative to the stator, wherein the rotor includes a rotor body defining a plurality of teeth, rotor windings wound around the plurality of teeth, a retaining wrap wound around the rotor body and configured to apply a compressive force to hold the rotor windings to the rotor body, and a compliance member configured to keep the retaining wrap within a predetermined tension range.

[0092] Example 18: The electromachine according to Example 17, wherein the predetermined tension range is between 10 percent and 50 percent of the ultimate strain of the holding wrap.

[0093] Example 19: The electromachine as in Example 18, wherein the retaining wrap is subjected to a pre-tension such that it equals approximately 30 percent of the ultimate strain of the retaining wrap.

[0094] Example 20: The electromechanical device according to Examples 17-19, wherein the compliance member is located within a winding channel formed between two adjacent teeth of a plurality of teeth.

[0095] Example 21: An electromachine according to Examples 17-20, wherein the compliance member is configured as a cooling can that surrounds the rotor winding coil.

[0096] Example 22: The electromachine according to Examples 17-21, wherein the compliance member is positioned radially between the retaining wrap and at least one of the rotor body and the rotor windings.

[0097] Example 23: The retaining wrap is wrapped around the rotor body in a circumferential direction, as described in Examples 17-22 of the electromachine.

[0098] Example 24: The electromachine according to Examples 17-23, wherein the retaining wrap is wrapped around the rotor body in the axial direction, and the retaining wrap extends between a first channel formed between adjacent teeth of a first pair of multiple teeth and a second channel formed between adjacent teeth of a second pair of multiple teeth.

[0099] Example 25: The electromachine according to Example 24, wherein the rotor includes a first end cap and a second end cap positioned at both ends of the rotor body, and a retaining wrap extends between the first and second channels along each of the first and second end caps to apply axial compression to the rotor body.

[0100] Example 26: The electromachine according to Examples 17-25, wherein the compliance member is configured to compensate for thermal expansion between the rotor and the retaining wrap, thereby keeping the retaining wrap within a predetermined tension range.

[0101] Example 27: The electromachine according to Examples 17-26, wherein the rotor further includes a retainer positioned between a retaining wrap and a compliance member, the retainer being configured to hold the retaining wrap in a predetermined shape.

[0102] Example 28: The electromachine according to Example 27, wherein the retainer and compliance member are integrally formed as a holder.

[0103] Example 29: An electromachine capable of changing the configuration of magnetic poles, comprising a stator and a rotor configured to rotate relative to the stator, wherein the rotor includes a plurality of rotor windings wound around a plurality of corresponding teeth extending from a rotor core, and the rotor core is made of a magnetizable material and configured to be selectively magnetized to a first magnetic pole configuration having a first number of magnetic poles and a second magnetic pole configuration having a second number of magnetic poles different from the first number of magnetic poles.

[0104] Example 30: The electromachine according to Example 29, wherein the first number of magnetic poles and the second number of magnetic poles equally divide the total number of teeth in multiple teeth.

[0105] Example 31: An electromachine according to Example 29 or 30, wherein the plurality of teeth consists of 4 teeth, the first number of magnetic poles includes 4 poles and the second number of magnetic poles includes 2 poles; the plurality of teeth consists of 6 teeth, the first number of magnetic poles includes 6 poles and the second number of magnetic poles includes 2 poles; and the plurality of teeth consists of 8 teeth, the first number of magnetic poles and the second number of magnetic poles are at least one selected from the group consisting of 8 poles, 4 poles, and 2 poles.

[0106] Example 32: The electromachine according to Examples 29-31, further comprising a controller configured to selectively magnetize the rotor core and switch between a first and second magnetic pole configuration.

[0107] Example 33: The electromachine according to Example 32, wherein the controller is configured to switch between a first magnetic pole configuration and a second magnetic pole configuration based on the operating parameters of the electromachine.

[0108] Example 34: The electromachine according to Example 33, wherein the operating parameters include at least one of the torque output or rotational speed of the electromachine.

[0109] Example 35: An electromachine according to Examples 32-34, wherein the stator includes stator windings, and the controller is configured to control the flow of current in the stator windings that induce a current corresponding to the rotor core, thereby switching the rotor core between a first pole configuration and a second pole configuration.

[0110] Example 36: An electromachine according to Examples 29-35, wherein each of the multiple teeth includes a pole cap made of electromagnetic steel, and the rotor core is made of carbon steel.

[0111] Example 37: A rotor assembly for an electromechanical device, the rotor comprising a rotor shaft including flanges positioned at its ends, a rotor body coupled to the rotor shaft, rotor windings supported on the rotor body, and a balance ring holding the rotor windings on the rotor body, wherein the balance ring defines an inner lip, the flanges bend toward the inner lip, and the rotor windings are held on the rotor shaft.

[0112] Example 38: The rotor assembly according to Example 37, wherein the flange provides axial compression to the balance ring, rotor windings, and back iron with respect to the rotor axis defined by the rotor shaft.

[0113] Example 39: The rotor assembly according to Example 37, further comprising a retainer positioned between the rotor windings and the rotor body.

[0114] Example 40: The rotor assembly according to Example 39, further comprising end caps configured to surround the rotor windings on a retainer, the end caps positioned between the rotor windings and the balance ring.

[0115] Example 41: The rotor assembly according to Example 40, further comprising end caps configured to surround the rotor windings on a retainer, the end caps positioned between the rotor windings and a balance ring.

[0116] Example 42: The rotor assembly according to Example 41, wherein the second balance ring holds the first balance ring on the rotor shaft.

[0117] Example 43: The rotor assembly according to Example 42, wherein the second balance ring defines an outer rim that curves onto the second inner lip of the first balance ring in order to hold the first balance ring on the rotor shaft.

Claims

1. A rotor for an electromachine, A rotor body defining a rotor axis and a plurality of teeth, wherein the plurality of teeth extend radially away from the rotor axis, The rotor windings wrapped around the aforementioned multiple teeth, Equipped with, The rotor body is Back irons, Multiple shanks extending radially away from the back iron, each corresponding to one of the multiple teeth, Multiple pole caps, each detachably coupled to a corresponding one of the multiple shanks, A rotor equipped with a rotor.

2. The aforementioned plurality of magnetic pole caps are made of the first material, At least one of the back iron and the plurality of shanks is made of a second material different from the first material. The rotor according to claim 1.

3. The first material is electrical steel, The second material is carbon steel. The rotor according to claim 2.

4. The aforementioned back iron is made of the second material, The aforementioned multiple shanks are made from a third material. The rotor according to claim 2.

5. The second material is a first electrical steel having a first grain orientation, The third material is a second electrical steel having a second grain orientation. The rotor according to claim 4.

6. The first grain orientation is an orientation along the circumferential direction with respect to the rotor axis, The second grain orientation is an orientation along the radial direction with respect to the rotor axis. The rotor according to claim 5.

7. The rotor body includes a laminate of thin plates formed by stacking a plurality of thin plates along the rotor axis. The rotor according to claim 1.

8. Each of the plurality of thin plates is a monolithic thin plate that forms both the back iron and the plurality of shanks. The rotor according to claim 7.

9. The aforementioned plurality of thin plates are A plurality of thin back iron plates that collectively form the aforementioned back iron, Multiple shank thin plates that collectively form the aforementioned multiple shanks, The rotor according to claim 7, including the rotor described in claim 7.

10. The first and second end caps are positioned at both ends of the rotor body, providing clamping force to the plurality of thin plates and holding the rotor windings on the rotor body. Furthermore, The rotor according to claim 9.

11. Each of the first end cap and the second end cap is made from at least one of a polymer material and a composite material. The rotor according to claim 10.

12. The plurality of magnetic pole caps are held on the rotor body by retaining wraps. The rotor according to claim 1.

13. Each of the plurality of magnetic pole caps is coupled to a corresponding one of the plurality of shanks by a coupling consisting of a lock and a key. The rotor according to claim 1.

14. Each of the plurality of magnetic pole caps is connected to a corresponding one of the plurality of shanks by a fastener. The rotor according to claim 1.

15. Each of the aforementioned shanks is connected to the back iron by a lock and key connection. The rotor according to claim 1.

16. The aforementioned back iron includes multiple back iron sections, Each of the aforementioned multiple back iron portions is configured to be coupled to a corresponding one of the aforementioned multiple shanks. The rotor according to claim 1.

17. It is an electrical machine, stator and, A rotor configured to rotate relative to the stator and The rotor is equipped with, A rotor body that defines multiple teeth, The rotor windings wrapped around the aforementioned multiple teeth, A retaining wrap is wrapped around the rotor body and configured to hold the rotor windings to the rotor body by applying a compressive force, A compliance member configured to maintain the retaining wrap within a predetermined tension range, Electrical machinery, including

18. The predetermined tension range is between 10 percent and 50 percent of the ultimate strain of the holding wrap. The electrical machine according to claim 17.

19. A pre-tension is applied to the retaining wrap such that it equals approximately 30 percent of the ultimate strain of the retaining wrap. The electrical machine according to claim 18.

20. The compliance member is positioned within a winding channel formed between two adjacent teeth among the plurality of teeth. The electrical machine according to claim 17.

21. The compliance member is configured as a cooling can that surrounds the rotor winding coil. The electrical machine according to claim 20.

22. The compliance member is positioned radially between the retaining wrap and at least one of the rotor body and the rotor windings. The electrical machine according to claim 17.

23. The retaining wrap is wrapped around the rotor body in the circumferential direction. The electrical machine according to claim 17.

24. The retainer is wrapped around the rotor body in the axial direction, and the retainer wrap extends between a first channel formed between adjacent teeth of a first pair of the plurality of teeth and a second channel formed between adjacent teeth of a second pair of the plurality of teeth. The electrical machine according to claim 17.

25. The rotor includes a first end cap and a second end cap positioned at both ends of the rotor body, The retaining wrap extends between the first and second channels along the first and second end caps, respectively, to apply axial compression to the rotor body. The electrical machine according to claim 24.

26. The compliance member is configured to compensate for thermal expansion between the rotor and the retaining wrap, thereby maintaining the retaining wrap within the predetermined tension range. The electrical machine according to claim 17.

27. The rotor further includes a retainer positioned between the retaining wrap and the compliance member, The retainer is configured to maintain the retaining wrap in a predetermined shape. The electrical machine according to claim 26.

28. The electric machine according to claim 27, wherein the retainer and the compliance member are integrally formed as a holder.

29. An electromachine capable of changing the configuration of magnetic poles, stator and, A rotor configured to rotate relative to the stator and Equipped with, The rotor includes a plurality of rotor windings wound around a plurality of corresponding teeth extending from a rotor core, the rotor core being made of a magnetizable material and configured to be selectively magnetized into a first pole configuration having a first number of poles and a second pole configuration having a second number of poles different from the first number of poles, an electromechanical device.

30. The first number of magnetic poles and the second number of magnetic poles divide the total number of teeth in the plurality of teeth equally. The electrical machine according to claim 29.

31. The aforementioned electrical machine is The aforementioned plurality of teeth consist of four teeth, the first number of magnetic poles includes four magnetic poles, and the second number of magnetic poles includes two magnetic poles. The aforementioned plurality of teeth consist of six teeth, the first number of magnetic poles includes six magnetic poles, and the second number of magnetic poles includes two magnetic poles. The plurality of teeth consist of eight teeth, and the first number of magnetic poles and the second number of magnetic poles are selected from the group consisting of eight magnetic poles, four magnetic poles, and two magnetic poles. It consists of at least one of the following: The electrical machine according to claim 30.

32. A controller configured to selectively magnetize the rotor core and switch between the first and second magnetic pole configurations. Furthermore, The electrical machine according to claim 29.

33. The controller is configured to switch between the first magnetic pole configuration and the second magnetic pole configuration based on the operating parameters of the electromachine. The electrical machine according to claim 32.

34. The aforementioned operating parameters include at least one of the torque output or rotational speed of the electric machine. The electrical machine according to claim 33.

35. The stator includes stator windings, The controller is configured to control the flow of current in the stator winding that induces a current corresponding to the rotor core, thereby switching the rotor core between the first magnetic pole configuration and the second magnetic pole configuration. The electrical machine according to claim 32.

36. Each of the aforementioned multiple teeth includes a magnetic pole cap made of electromagnetic steel, The rotor core is made of carbon steel. The electrical machine according to claim 29.

37. An electromechanical rotor assembly, A rotor shaft including flanges positioned at its ends, The rotor body is coupled to the rotor shaft, The rotor windings supported on the rotor body, A balance ring that holds the rotor windings on the rotor body, Equipped with, The balance ring defines an inner lip, and the flange bends toward the inner lip, holding the rotor windings on the rotor shaft. Rotor assembly.

38. The flange provides axial compression to the balance ring, the rotor windings, and the rotor body with respect to the rotor axis defined by the rotor shaft. The rotor assembly according to claim 37.

39. A retainer positioned between the rotor winding and the rotor body. Furthermore, The rotor assembly according to claim 37.

40. End cap configured to surround the rotor winding on the retainer. Furthermore, The rotor assembly according to claim 39, wherein the end cap is positioned between the rotor winding and the balance ring.

41. The balance ring includes a first balance ring and a second balance ring arranged concentrically with respect to the first balance ring, wherein the second balance ring defines a smaller diameter than the first balance ring. The rotor assembly according to claim 40.

42. The second balance ring holds the first balance ring on the rotor shaft. The rotor assembly according to claim 41.

43. The second balance ring defines an outer rim that curves toward the second inner lip of the first balance ring in order to hold the first balance ring on the rotor shaft. The rotor assembly according to claim 42.

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