Rotor assembly for a permanent magnet motor with radially offset shaft structure

Abstract

A rotor assembly for a permanent magnet motor defines an axis of rotation and includes a sheath member and a magnet member housed within the sheath member. The magnet member defines a central bore. The rotor assembly further includes a shaft structure having a base member and a biasing tab projecting from the base member. The biasing tab is housed within the central bore of the magnet member. The biasing tab biases the magnet member in a radially outward direction away from the axis of rotation toward the sheath member to hold the magnet member and the sheath member together.

Description

Technical Field

[0001] This disclosure generally relates to electric motors, and more specifically, to rotor assemblies for permanent magnet electric motors having a radially biased shaft structure. Background Technology

[0002] Permanent magnet motors can be used in a variety of applications. These motors offer high efficiency and other advantages.

[0003] However, many permanent magnet motors have defects. Manufacturing methods can be highly complex, labor-intensive, and / or otherwise inefficient. Typically, parts must maintain relatively high tolerances, which increases manufacturing complexity and cost.

[0004] Therefore, it is desirable to provide a high-quality permanent magnet electric motor that can be manufactured in an efficient manner. Other desirable features and characteristics of this disclosure will become apparent from the following detailed description and appended claims, taken in conjunction with the accompanying drawings and discussion of the background art. Summary of the Invention

[0005] In one embodiment, a rotor assembly for a permanent magnet electric motor is disclosed. The rotor assembly defines a rotation axis. The rotor assembly includes a sheath member and a magnet member received within the sheath member. The magnet member defines a central bore. The rotor assembly also includes a shaft structure having a base member and a biasing protrusion projecting from the base member. The biasing protrusion is received within the central bore of the magnet member. The biasing protrusion biases the magnet member toward the sheath member in a radially outward direction away from the rotation axis to hold the magnet member and the sheath member together.

[0006] In another embodiment, a method of manufacturing a rotor assembly for a permanent magnet motor is disclosed. The method includes providing a shaft structure having an axis. The shaft structure includes a base member and a biasing protrusion projecting axially from the base member along the axis. The biasing protrusion is elastically flexible relative to the base member between a neutral position and a loaded position. When moved from the neutral position toward the loaded position, the biasing protrusion elastically flexes toward the axis. Additionally, the method includes providing a magnet assembly including a magnet member received within a sheath member. The magnet member includes a central bore. Furthermore, the method includes moving the biasing protrusion into the central bore of the magnet member, including elastically flexing the biasing protrusion away from the neutral position and toward the loaded position to bias the magnet member toward the sheath member in a radially outward direction away from the axis to hold the magnet member and the sheath member together.

[0007] In another embodiment, a permanent magnet motor is disclosed. The motor includes a stator and a rotor assembly supported for rotation about an axis of rotation within the stator. The rotor assembly includes a hollow, cylindrical sheath member. The rotor assembly also includes a first and a second arcuate magnet segment received within the sheath member and extending about the axis of rotation. The magnet member defines a central bore having an open first axial end and an open second axial end. Furthermore, the rotor assembly includes a magnet interplate disposed circumferentially between the first and second arcuate magnet segments. Additionally, the rotor assembly includes a first axial end plate disposed adjacent to the first axial end and engaging with the magnet interplate. The rotor assembly also includes a second axial end plate disposed adjacent to the second axial end and engaging with the magnet interplate. The rotor assembly further includes a first shaft structure having a first base member and a plurality of first biasing protrusions projecting from the first base member. The first base member engages with the first axial end plate. The first biasing protrusions are disposed about the axis of rotation and spaced circumferentially. The first biasing protrusions are received within the central bore of the magnet member. The first biasing protrusion elastically bends inward toward the rotation axis from the neutral position toward the loading position, thereby biasing the first and second arcuate magnet segments radially outward away from the rotation axis. Furthermore, the rotor assembly includes a second shaft structure having a second base member and a plurality of second biasing protrusions projecting from the second base member. The second base member engages with a second axial end plate. The second biasing protrusions are disposed around the rotation axis and spaced circumferentially. The second biasing protrusions are received within a central hole in the magnet member and elastically bend inward toward the rotation axis from the neutral position toward the loading position, thereby biasing the first and second arcuate magnet segments radially outward away from the rotation axis. The plurality of first biasing protrusions are axially spaced from the second biasing protrusions. Attached Figure Description

[0008] The present disclosure will be described below in conjunction with the accompanying drawings, wherein like reference numerals denote like elements, and wherein: Figure 1 This is a schematic diagram of a fuel cell system with a permanent magnet motor according to an exemplary embodiment of the present disclosure; Figure 2 yes Figure 1 A perspective view of the rotor assembly of a permanent magnet motor, showing the rotor assembly in an assembled state.

[0009] Figure 3 yes Figure 2 Exploded perspective view of the rotor assembly; Figure 4 It is along Figure 2 A cross-sectional view of the rotor assembly taken from line 4-4; Figure 5 yes Figure 2 A perspective view of the shaft structure of the rotor assembly; and Figure 6 It is along Figure 2 The cross-sectional view of the rotor assembly is taken from line 6-6. Detailed Implementation

[0010] The following detailed description is exemplary in nature only and is not intended to limit this disclosure or its application and use. Furthermore, it is not intended to be bound by any theories presented in the preceding background or the following detailed description.

[0011] Broadly, the exemplary embodiments disclosed herein include robust, high-efficiency permanent magnet motors with rotor assemblies that offer improved manufacturability. The rotor assembly may include magnet members held together with a sheath member using one or more shaft structures. The one or more shaft structures may be preloaded to bias the magnet members toward the sheath member in a radially outward direction. This provides numerous manufacturing benefits, as will be discussed. Additionally, the motor offers high-efficiency operation, durability, and other advantages.

[0012] In some embodiments, the shaft structure may include one or more biasing members (e.g., biasing protrusions) that can be flexed radially inward. The biasing members may bend inward to apply a preload that, in turn, biases the magnet member radially outward. The biasing members may be arranged and spaced apart in the circumferential direction to distribute the bias load to the magnet member. Additionally, the biasing members may include one or more features, such as contoured surfaces, reduced-thickness regions, dimensions, etc., that ensure the biasing members accurately position and securely hold the magnet member. Furthermore, the biasing members may be configured such that the shaft structure and the final rotor assembly can be manufactured efficiently, accurately, and repeatably.

[0013] Additionally, the magnet component may include two or more segments. One or more biasing members of the shaft structure may cause the segments of the magnet component to be radially outwardly biased together to position and hold the magnet segments against the sheathing member. Furthermore, the rotor assembly may include one or more features that further hold the components together. For example, the rotor assembly may include one or more inter-magnet members and axial end members that engage with the magnet segments and / or sheathing members to securely hold the components together.

[0014] Now for reference Figure 1 The illustration shows a fuel cell system 100 having an example inflation device 102. The inflation device 102 includes an electric motor 103 having a rotor assembly 148 constructed according to exemplary embodiments of the present disclosure. It will be understood that the electric motor 103 and the rotor assembly 148 therein may be included in different systems (other than the fuel cell system) without departing from the scope of the present disclosure.

[0015] Fuel cell system 100 may include a fuel cell stack 104 comprising multiple fuel cells. Hydrogen may be supplied from tank 106 to fuel cell stack 104, and oxygen may be supplied to fuel cell stack 104 to generate electricity through a known chemical reaction. Fuel cell stack 104 may generate electricity for electric motor 105 and / or other connected electrical devices. Fuel cell system 100 may be included in vehicles such as automobiles, trucks, SUVs, vans, motorcycles, aircraft, etc. Thus, in some embodiments, electric motor 105 may convert the electricity generated by fuel cell stack 104 into mechanical power to drive and rotate the axles of the vehicle (and thus drive and rotate one or more wheels). However, it will be understood that fuel cell system 100 may be configured for different applications without departing from the scope of this disclosure.

[0016] Oxygen can be supplied at least partially to the fuel cell stack 104 by the aeration device 102. In some embodiments, the aeration device 102 may be configured as an electric compressor device (i.e., an electric booster) with a single-stage compressor.

[0017] like Figure 1 As shown, the inflation device 102 typically includes a rotating assembly 118 and a housing 119. The rotating assembly 118 may be supported by one or more bearings 121 to rotate about a rotation axis 120 within the housing 119. The one or more bearings 121 may have various configurations, such as sliding bearings, air bearings, oilless bearings, rolling element bearings, etc.

[0018] The inflation device 102 may define an electric motor portion 112. The electric motor portion 112 may include the electric motor 103 described above. In addition to the rotor assembly 148, the electric motor 103 may also include a stator 146 that houses the rotor assembly 148. The stator 146 may include a plurality of conductive windings. Furthermore, the electric motor portion 112 may include a portion of a housing 119. In one example, the electric motor portion 112 may include an electric motor housing 123 that supports the stator 146 and houses both the stator 146 and the rotor assembly 148. The rotor assembly 148 may include a magnet member 220, which will be discussed in detail below. In some embodiments, the fuel cell stack 104 may provide power to the stator 146 to drive the rotation of the magnet member 220 of the rotor assembly 148 and other components of the rotating assembly 118.

[0019] The inflation device 102 may also include a compressor section 110. In some embodiments, the compressor section 110 may be the only compressor section of the inflation device 102. In other embodiments, multiple compressor sections may be present to define a multi-stage inflation device 102. The compressor section 110 may include a compressor impeller 130, which is attached to the rotor assembly 148 to be part of the rotating assembly 118. Although in Figure 1As shown in the middle portion, the compressor impeller 130 may include a hub portion 145, which is secured to the rotor assembly 148 of the motor portion 112 via one or more fasteners, welds, and / or other attachments. The compressor portion 110 may also define a portion of a housing 119. Specifically, the compressor portion 110 may include a compressor housing member 136, which is secured to an axial end of the motor housing 123 and defines an axial inlet 138, a shroud member 139, and a volute member 140. The axial inlet 138, the shroud member 139, and the volute member 140 may be connected together as a single, integral compressor housing member 136. The axial inlet 138 may be tubular, straight, and centered on an axis 120. The shroud member 139 may be shaped in reverse order for the various components of the compressor impeller 130. The volute member 140 may define a volute passage 142 extending about the axis 120 therein. The volute member 140 may also define an outlet 143.

[0020] Therefore, the electric motor 103 can drive the compressor impeller 130 to rotate about axis 120. Inlet airflow (indicated by arrow 122) can flow into inlet 138, through shroud member 139, and into volute passage 142. The resulting compressed airflow (indicated by arrow 124) can be directed to intercooler 128 and then to fuel cell stack 104 to improve the operating efficiency of fuel cell system 100.

[0021] In addition, exhaust streams from fuel cell stack 104 (indicated by arrow 132) can be released into the atmosphere, such as... Figure 1 As shown. In other words, the exhaust flow 132 can be directed away from the inflation device 102. In other embodiments, the exhaust flow 132 can be directed back toward the inflation device 102, for example, to drive the turbine impeller included in the rotating assembly 118 to rotate. The rotating assembly 118 can then, for example, drive the rotation of the compressor impeller 130 to assist the electric motor 103.

[0022] The various components of the fuel cell system 100 can be controlled by the control system 134. The control system 134 may be a computerized system for electrically controlling the operation of the electric motor 103, the fuel cell stack 104, and / or other features of the system 100, and has a processor, various sensors, and other components. In some embodiments, the controller 134 may be defined or may be part of an electronic control unit (ECU) of the vehicle.

[0023] Now for reference Figure 2 The rotor assembly 148 of the electric motor 103 will be discussed in more detail based on exemplary embodiments of the present disclosure. The stator 146 is schematically shown in dashed lines to expose the rotor assembly 148.

[0024] As shown in the figure, the rotor assembly 148 may include a sheath member 210. The sheath member 210 may be a single, hollow tube. In some embodiments, the sheath member 210 may be centered on an axis 120. The sheath member 210 may include a first end 212 and a second end 214 spaced apart along the axis 120. Figure 3 and Figure 4 As shown, the sheath member 210 may further include an inner surface 216 (inner diameter surface) facing and surrounding the axis 120. For example... Figures 2-4 As shown, the sheath member 210 may further include an outer surface 218 (outer diameter surface) radially outward from axis 120. In some embodiments, the inner surface 216 and / or the outer surface 218 may be smooth and continuous. Additionally, in some embodiments, the inner surface 216 may be configured with a constant inner diameter radius, while the outer surface 218 may be configured with a constant outer diameter radius. Furthermore, the inner surface 216 may define a central hole 217 extending axially through the sheath member 210.

[0025] The rotor assembly 148 may also include a magnet member 220. The magnet member 220 may be generally cylindrical and hollow to define a central hole 226. Figure 1 and Figure 6 The central hole 226 can be centered on the magnet member 220 and can extend along axis 120 from the first end 222 of the opening to the second end 224 of the opening through the magnet member 220. Figure 1 ).

[0026] like Figure 3 As shown, the magnet component 220 may include and contain multiple segments constructed of and containing permanent magnets. For example, in some embodiments, the magnet component 220 includes a first arcuate magnet segment 228 and a second arcuate magnet segment 238. The first magnet segment 228 and the second magnet segment 238 may be arranged at different angular positions about axis 120. The first arcuate magnet segment 228 may be referred to as a north pole magnet, and the second arcuate magnet segment 238 may be referred to as a south pole magnet. Although only two magnet segments are shown, it will be understood that the magnet component 220 may include more than two segments arranged about axis 120 without departing from the scope of this disclosure.

[0027] like Figure 3 As shown, the first arcuate magnet segment 228 may be arcuate (e.g., semicircular) and may extend in the circumferential direction between a first circumferential edge 230 and an opposing second circumferential edge 232 about the axis 120. The first arcuate magnet segment 228 may also extend along the axis 120. The first arcuate magnet segment 228 may also include an inner surface 234 facing the axis 120 and arcuately profiled about the axis 120. Furthermore, an outer surface 236 may be radially outward from the axis 120 and arcuately profiled about the axis 120.

[0028] The second arcuate magnet segment 238 can be substantially similar to the first arcuate magnet segment 228. Therefore, the second arcuate magnet segment 238 can be arcuate (e.g., semi-circular) and can extend about axis 120 in the circumferential direction between the first circumferential edge 240 and the second circumferential edge 242. The second arcuate magnet segment 238 may also include an inner surface 244 facing axis 120 and arcuately profiled about axis 120. Furthermore, an outer surface 246 can face radially outward from axis 120 and can arcuately profiled about axis 120.

[0029] Furthermore, the magnet component 220 may include a first magnet interlayer plate 248 and a second magnet interlayer plate 250. The first magnet interlayer plate 248 and / or the second magnet interlayer plate 250 may be flat rectangular sheets of ferromagnetic material, such as magnetic steel. In some embodiments, plates 248 and 250 may have a constant sheet thickness. In some embodiments, plate 248 may be sandwiched between a first arcuate magnet segment 228 and a second arcuate magnet segment 238, and plate 250 may be sandwiched between segments 228 and 238 at different circumferential positions. In other words, the first magnet interlayer plate 248 may be disposed circumferentially between a first circumferential edge 230 of the first arcuate magnet segment 228 and a second circumferential edge 242 of the second arcuate magnet segment 238. Similarly, the second magnet interlayer plate 250 may be disposed circumferentially between a first circumferential edge 240 of the second arcuate magnet segment 238 and a second circumferential edge 232 of the first arcuate magnet segment 228. Therefore, in some embodiments, the first magnet spacer 248 and the second magnet spacer 250 may be spaced approximately 180 degrees apart from the axis 120.

[0030] The magnet component 220 may further include a first axial end plate 252. The first axial end plate 252 may be an annular disk made of a robust, rigid material. The first axial end plate 252 may include a central opening 251 centered on axis 120. The first axial end plate 252 may also include an annular groove 253 on its outer axial surface. The annular groove 253 may include an inner diameter surface 255 facing axis 120. In some embodiments, the inner diameter surface 255 may define at least a portion of the central opening 251.

[0031] Furthermore, the magnet component 220 may include a second axial end plate 266. The second axial end plate 266 may be substantially similar to the first axial end plate 252. Therefore, the second axial end plate 266 may be an annular disk made of a robust, rigid material. The second axial end plate 266 may include a central opening 261 centered on axis 120. Although not shown, the second axial end plate 266 may also include an annular groove (similar to groove 253) on its outer axial surface.

[0032] The first axial end plate 252 can be disposed on one axial end of the bow-shaped magnet segments 228 and 238. The second axial end plate 266 can be disposed on the opposite axial ends of the bow-shaped magnet segments 228 and 238. The outer axial surfaces of the first end plate 252 and the second end plate 266 can face away from the axial center of the magnet component 220 and can define the outer axial region of the magnet component 220.

[0033] In addition, such as Figure 3 and 4 As shown, the inner axial surface of the second axial end plate 266 may include a slot 274. The slot 274 may be straight and may extend radially. Figure 3 In some embodiments, the longitudinal axis of the slot 274 may intersect the axis 120, and the central opening 261 may bisect the slot 274. The slot 274 may be open at the outer diameter edge of the second axial end plate 266 and / or at the central opening 261. Figure 3 and 4 As shown, the first axial end plate 252 may similarly include a slot 254 on its inner axial surface.

[0034] Therefore, in some embodiments, the magnet member 220 may be defined by a first arcuate magnet segment 228 and a second arcuate magnet segment 238, a first magnet interplate 248 and a second magnet interplate 250, and a first axial end plate 252 and a second axial end plate 266. Thus, the arcuate magnet segments 228, 238, magnet interplates 248, 250, and end plates 252, 266 may be arranged around axis 120 and may collectively define a first end 222 and a second end of the opening of the magnet member 220. Furthermore, the inner surfaces 234, 244 of the magnet segments 228, 238 and the inner radial edges of the magnet interplates 248, 250 may define a large portion of the inner diameter surface of the magnet member 220.

[0035] like Figure 4 As shown, the first axial end plate 252 can engage with the first magnet interplate 248. For example, as shown, the axial edge of the magnet interplate 248 can be received within a slot 254 of the first axial end plate 252. Similarly, the opposing axial edges of the plate 248 can be received within a slot 274 of the second axial end plate 266 for engagement. Likewise, the second magnet interplate 250 can be received within slots 254 and 274 for engagement with the first axial end plate 252 and the second axial end plate 266. Therefore, the axial end plates 252 and 266 can be fixedly connected to the magnet interplates 248 and 250 and held against relative rotation about axis 120. Additionally, as... Figure 4As shown, the inner axial surfaces of the first axial end plate 252 and the second axial end plate 266 may be disposed adjacent to the axial ends of the first arcuate magnet segment 228 and the second arcuate magnet segment 238. In some embodiments, these opposing surfaces may be in abutment contact. Therefore, the magnet segments 228, 238, the end plates 252, 266, and the inter-magnet plates 248, 250 can be held together to rotate as a whole about axis 120, at least in part due to the engagement between the end plates 252, 266 and the inter-magnet plates 248, 250. In addition, the inter-magnet plates 248, 250 can limit (prevent) displacement of the magnet segments 228, 238 about axis 120 in the circumferential direction.

[0036] The magnet component 220 can be housed within the sheath component 210. As will be discussed, in some embodiments, the outer surface 236 of the first arcuate magnet segment 228 can abut against the inner surface 216 of the sheath component 210. Similarly, the outer surface 246 of the second arcuate magnet segment 238 can abut against the inner surface 216. Additionally, in some embodiments, the outer edges of the first magnet interplate 248 and the second magnet interplate 250 can abut against the inner surface 216. Furthermore, the outer diameter surfaces of the first axial end plate 252 and the second axial end plate 266 can approach (e.g., abut against) the inner surface 216.

[0037] The rotor assembly 148 may also include a shaft arrangement 280. The shaft arrangement 280 may have various configurations without departing from the scope of this disclosure. Typically, at least a portion of the shaft arrangement 280 may be received in and engaged with the magnet member 220 in a central bore 226. Additionally, the shaft arrangement 280 may have a preload that biases portions of the magnet member 220 radially outward toward and against the inner surface 216 of the sheath member 210, thereby positioning the magnet member 220 and holding the magnet member 220 and the sheath member 210 together. Furthermore, the shaft arrangement 280 may also support other features of the rotating assembly 118. For example, the compressor impeller 130 may be fixed to and supported thereon on the shaft arrangement 280 for rotation about axis 120. Additionally, in some embodiments, the shaft arrangement 280 may be supported by one or more bearings 121 for rotation about axis 120 relative to the stator 146 and housing 119.

[0038] Shaft arrangement 280 in Figure 5 The image is shown separately, with the magnet member 220 and the sheath member 210 shown partially and schematically in dashed lines. In some embodiments, the shaft arrangement 280 may include a first shaft structure 282 and a second shaft structure 296. The first shaft structure 282 may be referred to as a first short shaft because it extends partially along axis 120, while the second shaft structure 296 may be referred to as a second short shaft because it extends partially along axis 120. Additionally, as... Figure 1 As shown, the first shaft structure 282 and the second shaft structure 296 can be spaced apart along the axis 120 by an axial distance of 300, wherein the first shaft structure 282 is disposed near one axial end of the rotor assembly 148 and the second shaft structure 296 is disposed near the opposite axial end. The first shaft structure 282 can be substantially similar to the second shaft structure 296.

[0039] Usually, such as Figure 5 As shown, the first shaft structure 282 may be a single, integral component comprising a base member 284 and one or more first biasing protrusions 288 projecting axially from the base member 284. The base member 284 and the plurality of first biasing protrusions 288 may be made of a robust metallic material. Additionally, a hole 293 may extend through the first shaft structure 282. The hole 293 may include an opening centered on axis 120 and continuously extending through the base member 284 from one axial end of the first shaft structure 282 to the other between the first biasing protrusions 288.

[0040] Similarly, the second shaft structure 296 can be a single, integral component comprising a base member 297 and one or more second biasing protrusions 298 projecting axially from the base member 297. The base member 297 and the plurality of second biasing protrusions 298 can be made of a robust metallic material. Additionally, a hole 271 can extend through the second shaft structure 296. The hole 271 can include an opening centered on axis 120 and continuously extending through the base member 294 from one axial end of the first shaft structure 282 to the other between the second biasing protrusions 298.

[0041] like Figure 5 As shown, the first base member 284 and / or the second base member 297 may be hollow and substantially cylindrical, having one or more circumferential grooves, disc-shaped protrusions, etc. Additionally, the first base member 284 and / or the second base member 297 may include an outer axial end 285, an inner axial end 286, and an intermediate portion 287 axially disposed therebetween. The diameter of the intermediate portion 287 may be larger than the diameter of the outer axial end 285. The diameter of the intermediate portion 287 may be larger than the diameter of the inner axial end 286. Furthermore, the inner axial end 286 may include a shoulder 281 having a radially outwardly oriented outer diameter surface. Figure 1 As shown, the first base member 284 defines a base thickness 295, radially measured from the inner diameter surface of the defining hole 271 and the outer diameter surface of the first base member 284. The second base member 297 also defines a corresponding base thickness dimension. (As shown...) Figure 1As shown, the base thickness 295 of the first base member 284 can vary along axis 120 based on surface features (e.g., grooves and protrusions) included on the outer diameter surface of the first base member 284, while the thickness of the second base member 297 can vary along axis 120 based on diameter variations at the inner and outer diameter surfaces of the second base member 297. In some embodiments, the diameter of the hole 271 through the outer axial end 285 is larger than the diameter of the hole 271 through the inner axial end 286 to receive portions of the compressor impeller 130, fasteners, and / or other components of the rotating assembly 118.

[0042] The first biased protrusion 288 and / or the second biased protrusion 298 may include, for example: Figure 5 The finger-like elongated member is shown. A first biased protrusion 288 and / or a second biased protrusion 298 may be an elongated, substantially straight member having a first portion 289, an end portion 290, and an intermediate portion 291. The first portion 289 may be connected to an inner axial end portion 286, and the intermediate portion 291 and the end portion 290 may project axially from there, wherein the intermediate portion 291 is axially disposed between the first portion 289 and the end portion 290. The biased protrusions 288, 298 may have an inner surface 292, which faces radially inward and may define a portion of a corresponding hole 293, 271. In some embodiments, the inner surface 292 may be circumferentially profiled about axis 120 and may have a radius that remains constant along the axial length of the protrusions 288, 298. The biased protrusions 288, 298 may also have an outer surface 299, some portions of which may be planar and some portions of which may be profiled. Furthermore, the biased protrusions 288, 298 may include two planar side surfaces 301 facing each other in opposite tangential directions relative to the axis 120. Thus, in some embodiments, the inner surface 292, the outer surface 299, and the two side surfaces 301 may together define a rectangular cross-section (perpendicular to the axis 120) of the respective biased protrusions 288, 298.

[0043] like Figure 5As shown, the first biased protrusion 288 and / or the second biased protrusion 298 may have a thickness 302 (thickness dimension) measured radially between the inner surface 292 and the outer surface 299. The thickness 302 may vary along the length of the biased protrusions 288, 298. In some embodiments, the thickness 302 along the first portion 289 may gradually increase as the biased protrusions 288, 298 extend axially away from the axial end 286. The thickness 302 may gradually increase until reaching the intermediate portion 291, and across the intermediate portion 291, the thickness 302 may remain constant. Additionally, the thickness 302 may gradually decrease (narrow) along the end 290. In some embodiments, the end 290 may have a convex curvature, and the thickness may gradually decrease (narrow) until the end 290 terminates at the end 303. In some embodiments, the end 290 may have a three-dimensional profile such that the end 290 is profiled in a plane intersecting the end 290 and the axis 120, and in a plane perpendicular to the axis 120. These features allow for and facilitate the assembly of rotor assembly 148, as will be discussed in more detail below.

[0044] A first biased protrusion 288 may project axially from a first base member 284, while a second biased protrusion 298 may project axially from a second base member 297. The first biased protrusion 288 and / or the second biased protrusion 298 may be arranged in a circular configuration around axis 120 (e.g., spaced approximately uniformly circumferentially). This arrangement may be centered on axis 120. Any number of first biased protrusions 288 and any number of second biased protrusions 298 may be present. For example, as illustrated in the embodiment shown, nine first biased protrusions 288 spaced approximately forty-four-hundred-degree (40°) apart around axis 120 may be present. Similarly, nine second biased protrusions 298 spaced approximately forty-degree (40°) apart around axis 120 may be present. The first biased protrusions 288 may be substantially similar to each other. Additionally, the second biased protrusions 298 may be substantially similar to each other. Furthermore, in some embodiments, the first biased protrusions 288 and the second biased protrusions 298 may be substantially similar to each other.

[0045] The first portion 289 may be a region with reduced thickness, allowing for elastic buckling (bending) of the protrusions 288, 298 under radially inwardly applied loads. In other words, the thickness 302 across the first portion 289 ( Figure 5 The thickness of the base 295 of the connection near the first part 289 can be less than that of the first part 289. Figure 1 Additionally, the thickness 302 spanning the first portion 289 can be less than the thickness 302 spanning the intermediate portion 291. Accordingly, one or more offset protrusions 288, 298 can be elastically flexible relative to the respective base members 284, 297 between a neutral position and a loaded position. The neutral position is... Figure 6 The loading (flexing) position is shown in dashed lines and in solid lines. The biasing protrusions 288 and 298 are bendable about an axis that extends perpendicular to axis 120 near the first portion 289. Therefore, the first portion 289 may be referred to as the “bent portion” of the respective biasing protrusions 288 and 298. When moving from the neutral position toward the loaded position, the biasing protrusions 288 and 298 can bend elastically inward toward axis 120, thereby moving the intermediate portion 291 and the end portion 290 closer to axis 120. Conversely, when the applied load decreases or is removed, the biasing protrusions 288 and 298 can elastically recover radially outward toward the neutral position, thereby moving the intermediate portion 291 and the end portion 290 further away from axis 120.

[0046] like Figure 1 and Figure 6 As shown, the first shaft structure 282 and the second shaft structure 296 can be fixedly connected to the magnet component 220. For example, the first shaft structure 282 can be partially accommodated within a first end 222 of the central hole 226 of the magnet component 220, and the second shaft structure 296 can be partially accommodated within a second end 224 of the central hole 226 of the magnet component 220. The first biasing protrusion 288 and the second biasing protrusion 298 can be accommodated within the central hole 226 of the magnet component 220 and can extend axially toward each other. Figure 6 As shown, at least a portion of the outer surface 299 may abut and engage the inner diameter surface of the central hole 226. More specifically, some of the first biasing protrusions 288 and the second biasing protrusions 298 may abut the inner surface 234 of the first arcuate magnet segment 228, while other magnet segments may abut the inner surface 244 of the second arcuate magnet segment 238. Furthermore, in some embodiments, at least some of the first biasing protrusions 288 and the second biasing protrusions 298 may abut the inner edges of the magnet interplates 248, 250.

[0047] When the bias protrusions 288 and 298 are provided in the magnet component 220, they can be positioned in the loading position. Figure 6This is because the diameter of the central hole 226 is smaller than the diameter defined by the outer surfaces 299 of the bias protrusions 288 and 298. Therefore, when connected to the magnet member 220, the bias protrusions 288 and 298 can be biased to elastically recover toward a neutral position. Thus, the bias protrusions 288 and 298 have a bending preload that collectively biases the components of the magnet member 220 radially outward toward the inner surface 216 of the sheath member 210. This radial load can be distributed substantially uniformly around the axis 120. Specifically, the load from the first bias protrusion 288 and the second bias protrusion 298 can bias the first arcuate magnet segment 228 and the second arcuate magnet segment 238, as well as the first magnet interplate 248 and the second magnet interplate 250, outward against the inner diameter surface of the sheath member 210. A set of first biasing protrusions 288 and second biasing protrusions 298 biases the first arcuate magnet segment 228 approximately radially away from the axis 120, while another set of first biasing protrusions 288 and second biasing protrusions 298 biases the second arcuate magnet segment 238 approximately radially away from the axis 120. Therefore, the biasing protrusions 288 and 298 hold the magnet component 220 and the sheath component 210 together. The biasing protrusions 288 and 298 can also, for example, hold the arcuate magnet segments 228 and 238 and the sheath component 210 in a predetermined and fixed position by increasing friction therebetween.

[0048] Additionally, the inner axial end 286 of the first shaft structure 282 can be accommodated in the central opening 251 of the first axial end plate 252. Similarly, the inner axial end 286 of the second shaft structure 296 can be accommodated in the central opening 261 of the second axial end plate 266. In this position, the outer diameter surfaces of the shoulders 281 of the shaft structures 282 and 296 can respectively abut against the inner diameter surfaces 255 of the first axial end plate 252 and the second axial end plate 266. Therefore, the first shaft structure 282 can engage with the first axial end plate 252, and the outer axial end 285 can protrude axially away from the magnet member 220 and the sheath member 210. Likewise, the second shaft structure 296 can engage with the second axial end plate 266, and the outer axial end 285 can protrude axially away from the magnet member 220 and the sheath member 210.

[0049] Now refer to Figure 3The manufacture of rotor assembly 148 is discussed. The parts of rotor assembly 148 can be constructed or otherwise provided using casting technology, additive manufacturing, or other manufacturing methods. The first arcuate magnet segment 228, the first magnet interplate 248, the second arcuate magnet segment 238, and the second magnet interplate 250 can then be assembled together in the cylindrical configuration described above. Next, in some embodiments, a sheath member 210 can be placed on and accommodate the assembled first arcuate magnet segment 228, first magnet interplate 248, second arcuate magnet segment 238, and second magnet interplate 250.

[0050] In some embodiments, sufficient radial clearance (e.g., between the inner surface 216 and the outer surfaces 236, 246) may exist at room temperature (i.e., normal ambient temperature) or approximately room temperature to allow the sheath member 210 to slide over the magnet segments 228, 238 (i.e., without needing to heat the sheath member 210). Therefore, it is not necessary to heat-shrink the sheath member 210 over the magnet member 220. Thus, manufacturing can be accomplished efficiently.

[0051] Subsequently, axial end plates 252 and 266 can be positioned on the axial ends of the magnet member 220. In some embodiments, end plates 252 and 266 can be positioned to receive magnet interplates 248 and 250 in slots 254 and 274, respectively. Furthermore, shaft structures 282 and 296 can be positioned on end plates 252 and 266, wherein the ends 290 of the biased protrusions 288 and 298 abut the edges of the central openings 251 and 261, respectively.

[0052] Subsequently, an axial load (e.g., using a press) can be applied to compress the components of rotor assembly 148 together toward the axial center. As the load increases, the three-dimensional, convex-profile ends 290 can be inserted into the central openings 251, 261, causing the biased protrusions 288, 298 to move inward toward axis 120 in a cam-like manner and bend, thereby advancing the shaft structures 282, 296 inward toward the center of rotor assembly 148. This axial movement toward the center can be defined by the shaft structures 282, 296, which respectively mate, abut, and / or engage with the end plates 252, 266. Furthermore, this axial movement toward the center can be limited by the end plates 252, 266, which respectively mate, abut, and / or engage with the ends of magnet segments 228, 238. Additionally, this axial movement toward the center can be limited by the magnet interplates 248, 250 abutting the inner surfaces of slots 254, 274. Furthermore, when these components are compressed together, they can engage to position and guide the axial and radial movement of the shaft structures 282 and 296.

[0053] Once fully compressed, shaft structures 282, 296 can be securely connected to the sheath member 210. In some embodiments, shaft structures 282, 296 can be welded to the sheath member 210. For example, spot welding, laser welding, or other types of welding processes can be used to produce one or more weldments that securely connect the sheath member 210 to the shaft structures 282, 296. One or more weldments can be formed at equidistant locations around axis 120, or can be formed as partial or continuous arcuate weldments around axis 120. Thus, the rotor assembly 148 can be robust and durable, thereby holding the components together in the axial direction.

[0054] Furthermore, as discussed, the biasing protrusions 288 and 298 allow the components of the magnet assembly 220 to be radially biased outward against the sheath member 210. The sheath member 210 holds the magnet segments 228 and 238 in a fixed radial position. Thus, the rotor assembly 148 can be robust and durable, thereby holding the components together in the radial direction.

[0055] Additionally, the magnet interplates 248 and 250 can engage with the end plates 252 and 266, and limit (prevent) circumferential displacement of the magnet segments 228 and 238. Therefore, the rotor assembly 148 can be robust and durable, thereby holding the components together in the circumferential direction.

[0056] Furthermore, as described above, the assembly of rotor assembly 148 can be completed efficiently, repeatably, and accurately. Each component can be formed independently within very manageable tolerances. The bias protrusions 288 and 298 allow for precise assembly of the components, and the applied preload conveniently positions and holds magnet segments 228 and 238 in place.

[0057] Once assembled, the rotor assembly 148 can be connected to the compressor impeller 130 and / or mounted within the stator 146 of the electric motor 103. The electric motor 103 can then be installed within the fuel cell system 100.

[0058] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that numerous variations exist. It should also be understood that one or more exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or construction of this disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing exemplary embodiments of this disclosure. It should be understood that various changes can be made to the function and arrangement of the elements described in the exemplary embodiments without departing from the scope of this disclosure set forth in the appended claims.

Claims

1. A rotor assembly for a permanent magnet electric motor defining a rotation axis, the rotor assembly comprising: Sheath components; A magnet component, which is housed within the sheath component, the magnet component defining a central hole; A shaft structure having a base member and a biasing protrusion projecting from the base member, the biasing protrusion being received within the central hole of the magnet member, the biasing protrusion biasing the magnet member toward the sheath member in a radially outward direction away from the axis of rotation to hold the magnet member and the sheath member together. The offset protrusion protrudes axially from the base member along the axis of rotation; and The biased protrusion is elastically flexible between the neutral position and the loaded position; and The biased protrusion is in the loaded position, so that the magnet component is biased toward the sheath component in the radially outward direction.

2. The rotor assembly according to claim 1, wherein, The magnet component includes a first axial end of an opening and a second axial end of an opening, wherein the first axial end is opposite to the second axial end; The shaft structure is a first shaft structure having a first base member and a first biasing protrusion housed within the first axial end portion, the first biasing protrusion biasing the magnet member in the radially outward direction; and The shaft structure includes a second shaft structure having a second base member and a second biasing protrusion protruding from the second base member, the second biasing protrusion being received within the second axial end of the magnet member, the second biasing protrusion cooperating with the first biasing protrusion to bias the magnet member toward the sheath member in the radially outward direction to hold the magnet member and the sheath member together.

3. The rotor assembly according to claim 2, wherein, The first biased protrusion and the second biased protrusion are spaced apart by an axial distance measured along the axis of rotation.

4. The rotor assembly according to claim 1, wherein, The biased protrusion is one of a plurality of biased protrusions protruding from the base member, the plurality of biased protrusions being arranged around the axis of rotation; The plurality of biased protrusions collectively bias the magnet component radially outward toward the sheath component to hold the magnet component and the sheath component together.

5. The rotor assembly according to claim 4, wherein, The shaft structure includes the base member and the plurality of offset protrusions projecting axially from the base member; The plurality of offset protrusions are evenly spaced around the axis of rotation in the circumferential direction.

6. The rotor assembly according to claim 5, wherein, The magnet component includes a first bow-shaped magnet segment and a second bow-shaped magnet segment, which extend around the rotation axis. Wherein, the first group of the plurality of biased protrusions biases the first arcuate magnet segment toward the sheath member in a first radially outward direction; and The second group of the plurality of biased protrusions biases the second bow-shaped magnet segment toward the sheath member in the second radially outward direction.

7. The rotor assembly according to claim 6 further includes a magnet spacer plate disposed in the circumferential direction between the first bow-shaped magnet segment and the second bow-shaped magnet segment; It also includes an axial end plate positioned close to the axial end of the magnet component; and in, The magnet interplate is joined to the axial end plate.

8. The rotor assembly according to claim 1, wherein, The shaft structure includes a hole extending through it; The biased protrusion has an inner surface that partially defines the hole and an outer surface that faces outward away from the axis of rotation; The biased protrusion has a thickness measured radially between the inner surface and the outer surface, the thickness varying along the axial direction; Wherein, the biased protrusion includes an end portion, the end portion comprising the end of the biased protrusion; and The thickness gradually decreases along the end portion toward the end.

9. The rotor assembly according to claim 8, wherein, The offset protrusion has a convex curvature at the end portion.

10. The rotor assembly according to claim 9, wherein, The offset protrusion has a three-dimensional convex profile at the end portion.

11. The rotor assembly according to claim 8, wherein, The offset protrusion includes a curved portion and a middle portion, wherein the curved portion is connected to the base member, and wherein the middle portion is axially disposed between the curved portion and the end portion; and The base member has a base thickness measured radially near the curved portion; and Wherein, the thickness of the offset protrusion spanning the curved portion is less than the thickness of the base; and The thickness of the biased protrusion that spans the curved portion is less than the thickness of the biased protrusion that spans the intermediate portion.

12. A method for manufacturing a rotor assembly for a permanent magnet electric motor, comprising: A shaft structure with an axis is provided, the shaft structure including a base member and a biased protrusion projecting axially from the base member along the axis, the biased protrusion being elastically flexible relative to the base member between a neutral position and a loaded position, the biased protrusion elastically flexing toward the axis when moved from the neutral position to the loaded position; A magnet assembly is provided, comprising a magnet member housed within a sheath member, the magnet member including a central aperture; and Moving the bias protrusion into the center hole of the magnet member includes elastically flexing the bias protrusion away from the neutral position and toward the loading position so that the magnet member is biased toward the sheath member in a radially outward direction away from the axis to keep the magnet member and the sheath member together.

13. The method according to claim 12, wherein, The offset protrusion is one of a plurality of offset protrusions protruding from the base member, the plurality of offset protrusions being arranged around the axis; and It also includes connecting the shaft structure to the magnet assembly by moving the plurality of bias protrusions from the neutral position to the loading position to bias the magnet component radially outward toward the sheath component.

14. The method according to claim 13, wherein, The magnet component includes a first bow-shaped magnet segment and a second bow-shaped magnet segment, which extend around the axis. Connecting the shaft structure to the magnet assembly includes using a first set of the plurality of biasing protrusions to bias the first arcuate magnet segment toward the sheath member in a first radially outward direction; and Connecting the shaft structure to the magnet assembly includes using a second set of the plurality of bias protrusions to bias the second bow-shaped magnet segment toward the sheath member in a second radially outward direction.

15. The method of claim 14, further comprising providing an axial end plate adjacent to an axial end of the magnet member; It also includes providing a magnet spacer between the first and second bow-shaped magnet segments in the circumferential direction around the axis; and It also includes engaging the magnet interplate with the axial end plate.

16. The method according to claim 12, wherein, The biased protrusion has an inner surface and an outer surface, and a thickness measured radially between the inner surface and the outer surface, the thickness varying along the axial direction; The biased protrusion includes an end portion, which includes the end of the biased protrusion; Wherein, the thickness gradually decreases along the end portion toward the end; and Moving the biased protrusion into the central hole includes bringing the end portion close to the magnet member so that the biased protrusion moves inward toward the axis along a cam-like motion trajectory.

17. The method according to claim 16, wherein, The offset protrusion has a convex curvature at the end portion.

18. The method of claim 12, further comprising: A first axial end and a second axial end of an opening are provided for the magnet component, the first axial end being opposite to the second axial end; The shaft structure is provided as a first shaft structure, the first shaft structure having a first base member and a first biasing protrusion housed within the first axial end portion, the first biasing protrusion biasing the magnet member in the radially outward direction; and It also includes providing a second shaft structure, the second shaft structure including a second base member and a second biased protrusion projecting from the second base member, the second biased protrusion being elastically flexible relative to the second base member between a neutral position and a loaded position; and The method also includes moving the second bias protrusion into the second axial end by elastically flexing the second bias protrusion away from the neutral position and toward the loading position, so that the magnet member is biased toward the sheath member in the radially outward direction away from the axis, so as to hold the magnet member and the sheath member together.

19. A permanent magnet electric motor, comprising: stator; and The rotor assembly according to any one of claims 1-11.

Images