Rotor for electric machine and electric machine including the rotor

Abstract

A rotor for an electric machine includes a shaft extending between a first and second shaft ends, a first washer adjacent to the first shaft end, and a second washer adjacent to the second shaft end. The first washer has a first washer outer surface facing away from the shaft. The first washer has a proximal first washer end extending a first radial distance from the shaft to the first washer outer surface and a distal first washer end extending a second radial distance from the shaft to the first washer outer surface. The second radial distance is different than the first radial distance. The rotor includes a plurality of magnets disposed between the first washer and the second washer and a rotor sleeve disposed about the plurality of magnets and in contact with the first washer outer surface to retain the plurality of magnets to the shaft.

Description

ROTOR FOR ELECTRIC MACHINE AND ELECTRIC MACHINEINCLUDING THE ROTORCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and all the benefits of U.S. Provisional Patent Application Nos. 63 / 549676, filed February 5, 2024, and 63 / 739938, filed December 30, 2024, which are hereby expressly incorporated herein by reference in their entirety.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The invention generally relates to a rotor for an electric machine, and to an electric machine including the rotor.2. Description of the Related Art

[0003] Conventional rotors commonly include a shaft rotatable about an axis, a plurality of magnets disposed about the shaft, and first and second washers at either end of the shaft to axially retain the plurality of magnets to the shaft. Convention rotors also commonly include a sleeve disposed about the plurality of magnets and / or the first and second washers to radially retain the plurality of magnets to the shaft. Often, these sleeves are pre-formed and subsequently slid over the plurality of magnets. However, these sleeves are also known to be formed through a winding process directly onto the plurality of magnets. When formed through the winding process directly onto the plurality of magnets, conventional sleeves tend to shrink inward upon themselves and away from the first and second washers. Upon shrinking inward uponthemselves, the sleeves also move radially outward and loosen, permitting the plurality of magnets to slide radially away from the shaft. Thus, conventional sleeves fail to adequately radially retain the plurality of magnets to the shaft.

[0004] As such, there remains a need for an improved rotor for an electric machine.SUMMARY OF THE INVENTION AND ADVANTAGES

[0005] A rotor for an electric machine includes a shaft extending along an axis between a first shaft end and a second shaft end spaced from the first shaft end along the axis. The rotor also includes a first washer disposed about the shaft adjacent to the first shaft end of the shaft. The rotor further includes a second washer disposed about the shaft adjacent to the second shaft end of the shaft.

[0006] The first washer has a first washer outer surface facing away from the shaft. The first washer also has a proximal first washer end extending a first radial distance from the shaft to the first washer outer surface. The first washer further has a distal first washer end extending a second radial distance from the shaft to the first washer outer surface. The second radial distance is different than the first radial distance. The proximal first washer end is disposed between the distal first washer end and the second washer.

[0007] The rotor further includes a plurality of magnets disposed about the shaft between the first washer and the second washer. The rotor further includes a rotor sleeve disposed about the plurality of magnets and in contact with the first washer outer surface to retain the plurality of magnets to the shaft.

[0008] Accordingly, the first washer assists the rotor sleeve in retaining the plurality of magnets to the shaft.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0010] FIG. 1A is a perspective view of a rotor having a rotor sleeve;

[0011] FIG. IB is a cross-sectional view of the rotor of FIG. 1A, with the rotor including first and second washers and a plurality of magnets disposed between the first and second washers;

[0012] FIG. 1C is an expanded view of the rotor of FIG. IB, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the second radial distance greater than the first radial distance;

[0013] FIG. ID is a cross-sectional view of the rotor of FIG. 1 A and including first and second sacrificial materials;

[0014] FIG. 2A is a perspective view of another embodiment of the rotor having the rotor sleeve;

[0015] FIG. 2B is a cross-sectional view of the rotor of FIG. 2A;

[0016] FIG. 2C is an expanded view of the rotor of FIG. 2B, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the second radial distance greater than the first radial distance;

[0017] FIG. 2D is a cross-sectional view of the rotor of FIG. 2A and including first and second sacrificial materials;

[0018] FIG. 3A is a perspective view of another embodiment of the rotor having the rotor sleeve;

[0019] FIG. 3B is a cross-sectional view of the rotor of FIG. 3A;

[0020] FIG. 3C is an expanded view of the rotor of FIG. 3B, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the second radial distance greater than the first radial distance;

[0021] FIG. 3D is a cross-sectional view of the rotor of FIG. 3A and including first and second sacrificial materials;

[0022] FIG. 4A is a perspective view of another embodiment of the rotor having the rotor sleeve;

[0023] FIG. 4B is a cross-sectional view of the rotor of FIG. 4A;

[0024] FIG. 4C is an expanded view of the rotor of FIG. 4B, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the first radial distance greater than the second radial distance;

[0025] FIG. 4D is a cross-sectional view of the rotor of FIG. 4A and including first and second sacrificial materials;

[0026] FIG. 4E is a cross-sectional view of the rotor of FIG. 4A and including another embodiment of the first and second sacrificial materials;

[0027] FIG. 5A is a perspective view of another embodiment of the rotor having the rotor sleeve;

[0028] FIG. 5B is a cross-sectional view of the rotor of FIG. 5A;

[0029] FIG. 5C is an expanded view of the rotor of FIG. 5B, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the first radial distance greater than the second radial distance;

[0030] FIG. 5D is a cross-sectional view of the rotor of FIG. 5A and including first and second sacrificial materials;

[0031] FIG. 6A is a perspective view partially in cross-section of another embodiment of the rotor;

[0032] FIG. 6B is a cross-sectional view of the rotor of FIG. 6A; and

[0033] FIG. 6C is an expanded view of the rotor of FIG. 6B, with the first washer having a proximal first washer end extending a first radial distance from a shaft and a distal first washer end extending a second radial distance from the shaft, with the first radial distance greater than the second radial distance.DETAILED DESCRIPTION OF THE INVENTION

[0034] With reference to the Figures, wherein like numerals indicate like parts throughout the several views, a rotor 10 for an electric machine 12 is provided. The rotor 10 includes a shaft 14 extending along an axis Al between a first shaft end 16 and a second shaft end 18 spaced from the first shaft end 16 along the axis Al. The rotor 10 also includes a first washer20 disposed about the shaft 14 adjacent to the first shaft end 16 of the shaft 14. The rotor 10 furtherincludes a second washer 22 disposed about the shaft 14 adjacent to the second shaft end 18 of the shaft 1 .

[0035] The first washer 20 has a first washer outer surface 24 facing away from the shaft 14. The first washer 20 also has a proximal first washer end 26 extending a first radial distance RD1 from the shaft 14 to the first washer outer surface 24. The first washer 20 further has a distal first washer end 28 extending a second radial distance RD2 from the shaft 14 to the first washer outer surface 24. The second radial distance RD2 is different than the first radial distance RD1. The proximal first washer end 26 is disposed between the distal first washer end 28 and the second washer 22.

[0036] The rotor 10 further includes a plurality of magnets 30 disposed about the shaft 14 between the first washer 20 and the second washer 22. The plurality of magnets 30 may be permanent magnets. The rotor 10 further includes a rotor sleeve 32 disposed about the plurality of magnets 30 and in contact with the first washer outer surface 24 to retain the plurality of magnets 30 to the shaft 14. Accordingly, the first washer 20 assists the rotor sleeve 32 in retaining the plurality of magnets 30 to the shaft 14.

[0037] Although not required, the rotor sleeve 32 may be formed through an in- situ winding process. Said differently, the rotor sleeve 32 may be wound around the plurality of magnets 30 after the plurality of magnets 30 has been disposed about the shaft 14. The rotor sleeve 32 may include a fiber wound about the shaft 14. The fiber may be pre-impregnated with a resin prior to being wound about the shaft 14 to form the rotor sleeve 32. The resin pre-impregnated on the fiber is set, or dry, prior to being wound about the shaft 14 to form the rotor sleeve 32. Alternatively, the fiber may be wound about the shaft 14 while still wet. More specifically, the fiber may be directed through a bath of the resin and wound about the shaft 14 to form the rotorsleeve 32 prior to the resin setting, or drying. The fiber may extend continuously without having been cut. Moreover, the fiber may be wound about the shaft 14 such that the fiber extends from the second washer 22 to the first washer 20 in a first direction DR1, may reverse direction axially over the first washer outer surface 24, and may extend toward the second washer 22 in a second direction DR2 opposite the first direction DR1.

[0038] It is to be appreciated that the fiber may be a filament. Although not required, the fiber may be tensioned when wound about the plurality of magnets 30. The fiber may also be heated when wound about the plurality of magnets 30. The fiber further may be wound about the plurality of magnets 30 at a low inclination angle relative to adjacent strands of fiber, such as less than ten degrees, between one degree and eight degrees, between one degree and six degrees, between one degree and five degrees, between one degree and four degrees, between two degrees and five degrees, between two degrees and four degrees, between two degrees and three degrees, about two degrees, or about three degrees. A low inclination angle maximizes hoop strength in a radial direction. A winder machine may shuttle the fiber back and forth along the axis Al, building up multiple layers of fiber which form the rotor sleeve 32. The winder machine must change translational direction along the axis Al at, or near, the first washer 20 and the second washer 22 to wind back across the rotor 10 and build up multiple layers of fiber to form the rotor sleeve 32.

[0039] As described herein, the fiber may extend continuously without having been cut. Typical rotors including fiber-based rotor sleeves have fibers which are discontinuous due to having been cut, for example, by a slitting or diamond saw. Such a cut in the fibers results in scrap waste and reduces the ability of conventional rotor sleeves to maintain their shape and form. Instead, cuts in the fiber-based rotor sleeves tend to permit the conventional rotor sleeves to relax(e.g., contract upon themselves axially inwardly), and thus loosen the conventional rotor sleeves (e.g., expand radially outwardly) and permit the magnets held therein to move. It is therefore to be appreciated that the rotor 10 as described herein having a rotor sleeve 32 formed from fiber which extends continuously without having been cut results in a rotor 10 having better performance in retaining the plurality of magnets 30. It is also to be appreciated that the rotor 10 as described herein having a rotor sleeve 32 formed from fiber which extends continuously without having been cut results in a rotor 10 which produces less scrap waste. Further still, it is to be appreciated that the rotor 10 as described herein having a rotor sleeve 32 formed from fiber which extends continuously without having been cut eliminates a manufacturing step of cutting the rotor sleeve 32 which is currently required in conventional manufacturing processes, saving time (e.g., tack time) and increasing manufacturability of the rotor 10. Further even still, it is to be appreciated that the rotor 10 as described herein having a rotor sleeve 32 formed from fiber which extends continuously without having been cut is less hazardous for an operator manufacturing the rotor 10 because no fiber may be inhaled which may result in cutting the fiber of conventional rotor sleeves.

[0040] The first washer outer surface 24 may be textured to provide friction between the first washer 20 and the rotor sleeve 32. As non-limiting examples, the first washer outer surface 24 may be roughed, etched, engraved, or otherwise patterned to become textured to provide friction between the first washer 20 and the rotor sleeve 32.

[0041] Moreover, in the embodiments as shown in FIGS. 1A-1C and 4A-4C, the rotor sleeve 32 extends axially over the distal first washer end 28. In other words, the rotor sleeve 32 may overlap with the distal first washer end 28 along the axis Al. In other embodiments, as shown in FIGS. 2A-2C, 3A-3C, and 5A-5C, the distal first washer end 28 is free of the rotor sleeve32. Said differently, the rotor sleeve 32 may not overlap with the distal first washer end 28 alongthe axis Al. In the embodiments as shown in FIGS. 2A-2C, 3A-3C, and 5A-5C, the distal first washer end 28 which is free of the rotor sleeve 32 may be referred to as a land of the first washer 20.

[0042] In some embodiments, as shown in FIGS. 1A-1C, 2A-2C, and 3A-3C, the first radial distance RD1 of the proximal first washer end 26 is less than the second radial distance RD2 of the distal first washer end 28. Although not required, the distal first washer end 28 may be formed as a fence 34 extending radially away from the axis Al, as shown in FIGS. 2A-2C and 3A- 3C. The fence 34 may include a fence surface 36 facing the second rotor 10 and extending approximately perpendicularly relative to the axis Al. The first washer outer surface 24 may also have a radius which constantly increases between the proximal first washer end 26 and the distal first washer end 28, as shown in FIGS. 1A-1C. More specifically, the first washer outer surface 24 may include a linear ramp 38 which extends from the proximal first washer end 26 to the distal first washer end 28. Although not depicted, it is to be appreciated that the first washer outer surface 24 may alternatively be a curved ramp (i.e., not linear) which extends from the proximal first washer end 26 to the distal first washer end 28 such that the radius of the first washer outer surface 24 constantly increases between the proximal first washer end 26 and the distal first washer end 28. As shown in FIG. 3A-3C, the first washer outer surface 24 may even include a linear ramp 38 disposed between the proximal first washer end 26 and the distal first washer end 28, as well as the first washer outer surface 24 having the distal first washer end 28 being formed as the fence 34 extending radially away from the axis Al.

[0043] In other embodiments, as shown in FIGS. 4A-4C and 5A-5C, the first radial distance RD1 of the proximal first washer end 26 is greater than the second radial distance RD2 of the distal first washer end 28. As depicted, the first washer outer surface 24 may curve inwardlytoward the axis Al between the proximal first washer end 26 and the distal first washer end 28.Additionally, as shown in FIG. 6A, the first washer outer surface 24 may include a stepped portion 48 extending linearly toward the axis Al. Although not required, the rotor sleeve 32 may axially overlap the stepped portion 48 during formation of the rotor sleeve 32. The rotor sleeve 32 may be cut, such as with an end mill or diamond saw, such that the rotor sleeve 32 terminates at the stepped portion 48 of the first washer outer surface 24.

[0044] The shaft 14 has a middle shaft portion 40 disposed between the first washer 20 and the second washer 22, and the shaft 14 has a first end shaft portion 42 spaced radially inwardly from the first washer 20. The middle shaft portion 40 has a first radial shaft depth RSD1, and the first end shaft portion 42 has a second radial shaft depth RSD2. The second radial shaft depth RSD2 may be less than the first radial shaft depth RSD1 to seat the first washer 20 relative to the shaft 14.

[0045] It is to be appreciated that the second washer 22 may have the characteristics and designs of the first washer 20 as shown and described herein. It is further to be appreciated that the rotor 10 as shown and described herein may be incorporated into an electric machine 12. The electric machine 12 includes a stator 44 defining a stator interior 46, and the rotor 10 as shown and described herein may be disposed in the stator interior 46 of the stator 44. An exemplary electric machine 12 is shown in FIG. IB. It is to be appreciated, however, that any of the rotors 10 as depicted in FIGS. 1A-1C, 2A-2C, 3A-3C, 4A-4B, or 5A-5C, or as otherwise described herein, are suitable for use in the electric machine 12. The electric machine 12 may be further defined as an electric motor. In other words, the electric motor may convert electrical energy to rotational movement of the shaft 14. The electric machine 12 may also be further defined as an electric generator. The electric generator may convert rotational movement of the shaft 14 into electricalenergy. It is to be appreciated that the electric machine 12 may be both an electric motor and an electric generator, may be only an electric motor, or may be only an electric generator.

[0046] Also provided herein is a method of manufacturing the rotor 10 for the electric machine 12. The rotor 10 manufactured by the method may include any of the characteristics as described herein and as depicted in the figures. The method includes the step of disposing the first washer 20 about the shaft 14 adjacent to the first shaft end 16 of the shaft 14. The method also includes the step of disposing the plurality of magnets 30 about the shaft 14. The method further includes disposing the second washer 22 about the shaft 14 adjacent to the second shaft end 18 of the shaft 14 such that the plurality of magnets 30 are disposed between the first washer 20 and the second washer 22.

[0047] As described herein, the first washer 20 used in the method has a first washer outer surface 24 facing away from the shaft 14. The first washer 20 used in the method also has a proximal first washer end 26 extending a first radial distance RD1 from the shaft 14 to the first washer outer surface 24. The first washer 20 used in the method further has a distal first washer end 28 extending a second radial distance RD2 from the shaft 14 to the first washer outer surface 24. The second radial distance RD2 is different than the first radial distance RD1, The proximal first washer end 26 of the first washer 20 used in the method is disposed between the distal first washer end 28 and the second washer 22.

[0048] The method further includes the step of disposing the rotor sleeve 32 about the plurality of magnets 30 such that the rotor sleeve 32 is in contact with the first washer outer surface 24 to retain the plurality of magnets 30 to the shaft 14. The method may be further defined as an in-situ winding process. Said differently, the rotor sleeve 32 may be wound about the plurality of magnets 30 after the plurality of magnets 30 has been disposed about the shaft 14.

[0049] Another embodiment of a method of manufacturing a rotor 10 for an electric machine 12 is also provided. The method includes providing a shaft 14 extending along an axis Al between a first shaft end 16 and a second shaft end 18 spaced from the first shaft end 16 along the axis Al, disposing a first washer 20 about the shaft 14 adjacent to the first shaft end 16 of the shaft 14, disposing a second washer 22 about the shaft 14 adjacent to the second shaft end 18 of the shaft 14, and disposing a plurality of magnets 30 about the shaft 14 between the first washer 20 and the second washer 22. The first washer 20 includes a first sacrificial material 50 at a distal first washer end 28 of the first washer 20, as is shown in FIGS. ID, 2D, 3D, 4D, 4E, 5D, 6B, and 6C. The method further includes removing the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 such that the first washer 20 has a first washer outer surface 24 facing away from the shaft 14, a proximal first washer end 26 extending a first radial distance RD1 from the shaft 14 to the first washer outer surface 24, and the distal first washer end 28 extending a second radial distance RD2 from the shaft 14 to the first washer outer surface 24. The second radial distance RD2 is different than the first radial distance RD 1. The proximal first washer end 26 is disposed between the distal first washer end 28 and the second washer 22.

[0050] The method may further include the step of disposing a rotor sleeve 32 about the plurality of magnets 30 and in contact with the first washer outer surface 24 to retain the plurality of magnets 30 to the shaft 14. More specifically, the step of disposing the rotor sleeve 32 about the plurality of magnets 30 may include forming the rotor sleeve 32 through an in-situ winding process. The step of disposing the rotor sleeve 32 about the plurality of magnets 30 and in contact with the first washer outer surface 24 to retain the plurality of magnets 30 to the shaft 14 may precede the step of removing the first sacrificial material 50 from the distal first washer end 28 of the first washer 20.

[0051] The second washer 22 may also include a second sacrificial material 52 at a distal second washer end 58 of the second washer 22. The method may further include the step of removing the second sacrificial material 52 from the distal second washer end 58 of the second washer 22 such that the second washer 22 has a second washer outer surface 54 facing away from the shaft 14, a proximal second washer end 56 extending the first radial distance RD1 from the shaft 14 to the second washer outer surface 54, and the distal second washer end 58 extending the second radial distance RD2 from the shaft 14 to the second washer outer surface 54. The second radial distance RD2 is different from the first radial distance RD1. The proximal second washer end 56 is disposed between the distal second washer end 58 and the first washer 20. The second washer 22 may be an identical mirror image of the first washer 20.

[0052] Removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22 may balance rotation of the rotor 10 about the axis Al. Rotational imbalance of the rotor 10 about the axis Al may result in damage to the components of the rotor 10 as well as adjacent components (e.g., the stator 44). Thus, the method provides both retention of the rotor sleeve 32 to the plurality of magnets 30 and rotational balance of the rotor 10 about the axis Al.

[0053] The rotor 10 as shown in FIG. ID includes the first sacrificial material 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 1A-1C. The rotor 10 as shown in FIG. 2D includes the first sacrificialmaterial 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 2A-2C. The rotor 10 as shown in FIG. 3D includes the first sacrificial material 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 3A-3C.

[0054] The rotor 10 as shown in FIG. 4D includes the first sacrificial material 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 4A-4C. Moreover, the rotor 10 as shown in FIG. 4E includes the first sacrificial material 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 4A-4C. Thus, it is to be appreciated that the first and second sacrificial materials 50, 52 may form any shape. The shape of the first and second sacrificial materials 50, 52 may be informed by the ease of manufacture of the first andsecond washers 20, 22, including the ease of manufacture of the shapes of the first and second sacrificial materials 50, 52. The shape of the first and second sacrificial materials 50, 52 may also be informed by amount of mass available to be removed to assist in balancing rotation of the rotor 10 about the axis Al.

[0055] The rotor 10 as shown in FIG. 5D includes the first sacrificial material 50 at the distal first washer end 28 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown throughout FIGS. 5A-5C. The rotor 10 as shown in FIGS. 6B and 6C includes the first sacrificial material 50 at the distal first washer end 58 of the first washer 20 and the second sacrificial material 52 at the distal second washer end 58 of the second washer 22. After removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 and removal of the second sacrificial material 52 from the distal second washer end 58 of the second washer 22, the resultant rotor 10 is shown in FIGS. 6A. The rotor 10 as shown in 6A has also had the rotor sleeve 32 disposed about the plurality of magnets 30. Additionally, as shown in FIG. 6A, the first washer outer surface 24 may include a stepped portion 48 extending linearly toward the axis Al. Thus, it is to be appreciated that removal of the first sacrificial material 50 from the distal first washer end 28 of the first washer 20 may form the stepped portion 48 extending linearly toward the axis Al.

[0056] The step of removing the first sacrificial material 50 from the distal first washer end 28 may include end-milling the first sacrificial material 50 with an end mill. Endmilling the first sacrificial material 50 with the end-mill may be accomplished such that the firstsacrificial material 50 is removed along a cross-section which is radially normal to the axis Al. As such, complex machinery which is capable of removing material through key-cuts is not necessary. The step of removing the second sacrificial material 52 from the distal second washer end 58 may include end-milling the second sacrificial material 52 with the end mill. End-milling the second sacrificial material 52 with the end-mill may be accomplished such that the second sacrificial material 52 is removed along a cross-section which is radially normal to the axis Al.

[0057] Although not required, the rotor sleeve 32 may be formed such that a portion of the rotor sleeve 32 axially overlaps with the first sacrificial material 50 and / or the second sacrificial material 52. As such, the step of removing the first sacrificial material 50 and / or the step of removing the second sacrificial material 52 may also remove material from the rotor sleeve 32. In the embodiments where the first sacrificial material 50 and / or the second sacrificial material 52 are removed by end-milling with an end mill, the material of the rotor sleeve 32 may also be removed by end-milling with the end mill. Despite the advantages of end-milling the first sacrificial material 50 and / or the second sacrificial material 52 with the end mill (e.g., ease of operation, removal along a cross-section radially normal to the axis Al, etc.), end-milling the rotor sleeve 32 may disadvantageous^ create highly fibrillated fibers at the distal edge(s) of the rotor sleeve 32. Thus, the method may further include the step of cutting the rotor sleeve 32 with a saw, such as a diamond saw, to generate a clean distal edge of the rotor sleeve 32.

[0058] A method of manufacturing an electric machine 12 includes the steps of providing a stator 44 defining a stator interior 46 and disposing the rotor 10 as manufactured by the method of manufacturing the rotor 10 in the stator interior 46 of the stator 44.

[0059] The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words ofdescription rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.

Claims

CLAIMSWhat is claimed is:

1. A rotor for an electric machine, said rotor comprising; a shaft extending along an axis between a first shaft end and a second shaft end spaced from said first shaft end along said axis; a first washer disposed about said shaft adjacent to said first shaft end of said shaft; a second washer disposed about said shaft adjacent to said second shaft end of said shaft; wherein said first washer has, a first washer outer surface facing away from said shaft, a proximal first washer end extending a first radial distance from said shaft to said first washer outer surface, and a distal first washer end extending a second radial distance from said shaft to said first washer outer surface, with said second radial distance different than said first radial distance, and with the proximal first washer end disposed between said distal first washer end and said second washer; a plurality of magnets disposed about said shaft between said first washer and said second washer; and a rotor sleeve disposed about said plurality of magnets and in contact with said first washer outer surface to retain said plurality of magnets to said shaft.

2. The rotor as set forth in claim 1 , wherein said rotor sleeve has been formed through an in- situ winding process.

3. The rotor as set forth in any one of claims 1 and 2, wherein said rotor sleeve comprises a fiber wound about said shaft.

4. The rotor as set forth in claim 3, wherein said fiber is pre-impregnated with a resin prior to being wound about said shaft to form said rotor sleeve.

5. The rotor as set forth in any one of claims 3 and 4, wherein said fiber extends continuously without having been cut.

6. The rotor as set forth in any one of claims 3-5, wherein said fiber is wound about said shaft such that said fiber extends from said second washer to said first washer in a first direction, reverses direction axially over said first washer outer surface, and extends toward said second washer in a second direction opposite said first direction.

7. The rotor as set forth in any one of claims 1-6, wherein said first washer outer surface is textured to provide friction between said first washer and said rotor sleeve.

8. The rotor as set forth in any one of claims 1-7, wherein said rotor sleeve extends axially over said distal first washer end.

9. The rotor as set forth in any one of claims 1-7, wherein said distal first washer end is free of said rotor sleeve.

10. The rotor as set forth in any one of claims 1-9, wherein said first radial distance of said proximal first washer end is less than said second radial distance of said distal first washer end.

11. The rotor as set forth in claim 10, wherein said distal first washer end is formed as a fence extending radially away from said axis.

12. The rotor as set forth in claim 11, wherein said fence includes a fence surface facing said second rotor and extending approximately perpendicularly relative to said axis.

13. The rotor as set forth in claim 10, wherein said first washer outer surface has a radius which constantly increases between said proximal first washer end and said distal first washer end.

14. The rotor as set forth in claim 13, wherein said first washer outer surface includes a linear ramp which extends from said proximal first washer end to said distal first washer end.

15. The rotor as set forth in claim 10, wherein said first washer outer surface includes a linear ramp disposed between said proximal first washer end and said distal first washer end, and wherein said distal first washer end is formed as a fence extending radially away from said axis.

16. The rotor as set forth in any one of claims 1-9, wherein said first radial distance of said proximal first washer end is greater than said second radial distance of said distal first washer end.

17. The rotor as set forth in claim 16, wherein said first washer outer surface curves inwardly toward said axis between said proximal first washer end and said distal first washer end.

18. The rotor as set forth in claim 16, wherein said first washer outer surface includes a stepped portion extending linearly toward said axis.

19. The rotor as set forth in any one of claims 1-18, wherein said shaft has a middle shaft portion disposed between said first washer and said second washer, wherein said shaft has a first end shaft portion spaced radially inwardly from said first washer, wherein said middle shaft portion has a first radial shaft depth, and wherein said first end shaft portion has a second radial shaft depth less than said first radial shaft depth to seat said first washer relative to said shaft.

20. An electric machine comprising a stator defining a stator interior and said rotor as set forth in any one of claims 1-19 disposed in said stator interior.

21. An electric machine comprisin :a stator defining a stator interior; and a rotor disposed in said stator interior of said stator, said rotor comprising: a shaft extending along an axis between a first shaft end and a second shaft end spaced from said first shaft end along said axis; a first washer disposed about said shaft adjacent to said first shaft end of said shaft; a second washer disposed about said shaft adjacent to said second shaft end of said shaft; wherein said first washer has, a first washer outer surface facing away from said shaft, a proximal first washer end extending a first radial distance from said shaft to said first washer outer surface, and a distal first washer end extending a second radial distance from said shaft to said first washer outer surface, with said second radial distance different than said first radial distance, and with the proximal first washer end disposed between said distal first washer end and said second washer; a plurality of magnets disposed about said shaft between said first washer and said second washer; and a rotor sleeve disposed about said plurality of magnets and in contact with said first washer outer surface to retain said plurality of magnets to said shaft.

22. The electric machine as set forth in any one of claims 20 and 21, wherein said electric machine is further defined as an electric motor.

23. The electric machine as set forth in any one of claims 20 and 21, wherein said electric machine is further defined as an electric generator.

24. A method of manufacturing a rotor for an electric machine, said method comprising: providing a shaft extending along an axis between a first shaft end and a second shaft end spaced from the first shaft end along the axis; disposing a first washer about the shaft adjacent to the first shaft end of the shaft, wherein the first washer includes a first sacrificial material at a distal first washer end of the first washer; disposing a second washer about the shaft adjacent to the second shaft end of the shaft; disposing a plurality of magnets about the shaft between the first washer and the second washer; removing the first sacrificial material from the distal first washer end of the first washer such that the first washer has, a first washer outer surface facing away from the shaft, a proximal first washer end extending a first radial distance from the shaft to the first washer outer surface, and the distal first washer end extending a second radial distance from the shaft to the first washer outer surface, with the second radial distance different than the first radial distance, and with the proximal first washer end disposed between the distal first washer end and the second washer.

25. The method of manufacturing the rotor as set forth in claim 24 further comprising the step of disposing a rotor sleeve about the plurality of magnets and in contact with the first washer outer surface to retain the plurality of magnets to the shaft.

26. The method of manufacturing the rotor as set forth in claim 25, wherein the step of disposing the rotor sleeve about the plurality of magnets and in contact with the first washer outersurface to retain the plurality of magnets to the shaft precedes the step of removing the first sacrificial material from the distal first washer end of the first washer.

27. The method of manufacturing the rotor as set forth in any one of claims 25 and 26, wherein the step of disposing the rotor sleeve about the plurality of magnets includes forming the rotor sleeve through an in-situ winding process.

28. The method of manufacturing the rotor as set forth in any one of claims 24-27, wherein the second washer includes a second sacrificial material at a distal second washer end of the second washer, further comprising the step of removing the second sacrificial material from the distal second washer end of the second washer such that the second washer has, a second washer outer surface facing away from the shaft, a proximal second washer end extending the first radial distance from the shaft to the second washer outer surface, and the distal second washer end extending the second radial distance from the shaft to the second washer outer surface, with the second radial distance different than the first radial distance, and with the proximal second washer end disposed between the distal second washer end and the first washer.

29. The method of manufacturing the rotor as set forth in claim 28, wherein removal of the first sacrificial material from the distal first washer end of the first washer and removal of the second sacrificial material from the distal second washer end of the second washer balances rotation of the rotor about the axis.

30. The method of manufacturing the rotor as set forth in any one of claims 28 and 29, wherein the step of removing the second sacrificial material from the distal second washer end includes end-milling the second sacrificial material with an end mill.

31. The method of manufacturing the rotor as set forth in any one of claims 24-30, wherein the step of removing the first sacrificial material from the distal first washer end includes end-milling the first sacrificial material with an end mill.

32. A method of manufacturing an electric machine comprising the steps of providing a stator defining a stator interior and disposing the rotor as manufactured by the method of manufacturing the rotor as set forth in any one of claims 24-31 in the stator interior of the stator.

Images