Motor rotor

Abstract

A motor rotor includes a core, a magnet, and a resin. The core defines a pocket. The core defines a notch extending from an outer end of each pocket. The core defines cavities, each cavity extending between the inner ends of two of the pockets and connecting the two pockets. The magnet is disposed within each of the pockets. And the resin is arranged in each concave cavity and each cavity. The resin encapsulates each magnet and fixes each magnet to at least one of the plates. The washers are each disposed along an outer end of each pocket. The gasket is configured to retain the resin within the pocket and the cavity. The gasket is also configured to isolate the resin from the notch.

Description

Technical Field

[0001] The present disclosure relates to a rotor for a permanent magnet electric machine. Background Art

[0002] Electric motors usually use a rotor and a stator to generate torque. Current flows through the stator winding to generate a magnetic field. The magnetic field generated by the stator can cooperate with the permanent magnets in the rotor to generate torque. Summary of the invention

[0003] A motor rotor includes a plurality of plates, magnets, couplers, molding compounds and washers. The plates are stacked along an axis. Each of the plates defines a pair of recesses. Each of the plates defines a notch extending from the outer end of each recess to the outer periphery of the plate. Each of the plates defines a bridging cavity extending between and connecting the inner ends of each recess in each pair of the paired recesses. The magnet is disposed in each of the recesses. The coupler is disposed in each of the bridging cavities and fixes the outer portion of each plate to the base portion of each plate. Each outer portion of each plate is separated from the base portion of each plate by an opening formed by a pair of the paired recesses, two of the notches and one of the bridging cavities. The molding compound is disposed in each recess and each bridging cavity. The molding compound encapsulates each magnet, encapsulates each coupler, fixes each magnet to at least one of the plates, and fixes each coupler to at least one of the plates. The washers are disposed along the outer ends of each recess, respectively, and are configured to retain the molded material within the recess and the bridge cavity, and to isolate the molded material from the notch.

[0004] A motor rotor includes a core, a magnet and a resin. The core defines pockets. The core defines a notch extending from the outer end of each pocket. The core defines a cavity, each cavity extending between the inner ends of two of the pockets and connecting the two pockets. The magnet is disposed in each of the pockets. The resin is disposed in each pocket and each cavity. The resin encapsulates each magnet and fixes each magnet to at least one of the plates. The washers are each disposed along the outer end of each pocket. The washers are configured to retain the resin in the pockets and the cavity. The washers are also configured to isolate the resin from the notch.

[0005] A motor rotor includes stacked plates, magnets, connectors, resin and washers. The stacked plates define pockets. The stacked plates define recesses, which extend from the outer end of each pocket to the outer periphery of the plate. The stacked plates define connecting cavities, each of which extends between the inner ends of two of the pockets and connects the two pockets. The magnet is disposed in each of the pockets. The connector is disposed in each of the connecting cavities and fixes the outer portion of the plate to the base portion of the plate. The resin is disposed in each pocket and each cavity. The resin encapsulates each magnet and connector. The resin fixes each magnet and connector to at least one of the plates. The washers are each disposed between one of the pockets and one of the recesses. The washers are configured to keep the resin in the pockets and the cavity. The washers are also configured to isolate the resin from the recesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an isometric view of a rotor for an electric machine, the rotor being formed from a plurality of stacked laminates or laminations;

[0007] Figure 2 It includes Figure 1 an isometric view of a portion of a rotor of region A;

[0008] Figure 3 It includes Figure 1 an isometric view of a portion of a rotor of region B; and

[0009] Figure 4 is included with Figure 2 An alternative configuration of a rotor having a portion similar to that of the rotor shown in;

[0010] Figure 5 is a perspective view of the stator; and

[0011] Figure 6 is a perspective view of an electric machine having a stator and a rotor. DETAILED DESCRIPTION

[0012] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as limiting, but only as a representative basis for teaching those skilled in the art to adopt the embodiments in different ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the drawings may be combined with the features shown in one or more other drawings to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.

[0013] The permanent magnet motor rotor requires the magnets to be fixed in the recesses cut out of the laminate. The motor described herein can be a motor, a generator, or a combined device that can operate as both a motor and a generator. The retention of the magnets prevents position changes during operation, which will cause rotor imbalance, variable electromagnetic properties, and potential magnet throw-out. Glue, bent tabs, and molded epoxy resins, as well as other methods, all provide the ability to constrain the magnets in the desired position. However, molded resins or epoxies are ubiquitous because they enhance the thermal and mechanical properties of the rotor system.

[0014] It is desirable to remove the bridges within the plates that define the pockets in which the magnets are located. The removal of such bridges reduces the low resistivity medium through which flux leakage may occur around the magnets, thereby reducing losses and allowing the magnet size to be reduced to achieve equivalent performance. The challenge of implementing a favorable molded epoxy fixing method (i.e., fixing the magnets to the laminate within the pockets via a molding resin or epoxy) with such a bridgeless rotor stems from the lack of boundary features that allow the molding compound to be injected and contained within the pockets. The current problem addressed herein is a system by which epoxy can be molded and contained within a specified area within the rotor without the need to use any conductive material in the space (i.e., the open space where the bridges in the laminate have been removed) that would increase flux leakage.

[0015] The proposed solution described herein consists of a plurality of electrical steel laminates or laminations comprising a stack or sub-stack of a rotor core forming a rotor core. Depending on the specific electrical machine architecture, multiple sub-stacks may be required to form a rotor core.

[0016] A representative slice of a rotor core depicts a typical layout of a double V magnet configuration, in which a set of large and small magnets form a V shape near the outer diameter of the rotor. It should be noted that some configurations may include only a single V-shaped magnet configuration. The cutouts in the laminations form the space (e.g., a pocket) occupied by the magnet. There is a gap in the position where the outer bridge would normally occupy because the outer bridge has been eliminated to reduce flux leakage around the magnet. An electrically insulating insert, connector, or coupler is located at the center of the V. The insert, connector, or coupler may form a dovetail to secure separate sections of the laminate or lamination to each other. The purpose of the insert is to support the centrifugal loads on the rotor core during operation of the motor without conducting flux, thereby avoiding providing a leakage path. Although each sub-stack is composed of multiple laminates or laminations, the magnets and inserts may be a solid body spanning the entire height of the sub-stack (or multiple sub-stacks with a non-skewed rotor).

[0017] Opposite the insert on the other end of the magnet is a deformable gasket. The gasket can be the entire height of the sub-stack and is wedged between the magnet and the undercut in the magnet pocket. The compressed gasket seals the magnet pocket, allowing injection of molding compound (e.g., resin or epoxy). Flat, C-shaped or alternatively configured gaskets can be used to seal the pockets. C-shaped and U-shaped gaskets also provide the benefit of centering each magnet within a corresponding pocket defined by the laminate or stack. The molding compound encapsulates the magnet and insert, filling the gaps in the magnet pockets and the gaps around the inserts where the bridges between pairs of pockets have been removed. The molding compound is contained by the gaskets at both ends.

[0018] The solution described herein achieves complete elimination of central bridges and outer bridges (i.e., bridges between pairs of magnets and bridges between each magnet and the outer periphery of a laminate or lamination) while also utilizing a molding compound (e.g., epoxy or resin). Utilizing a molding compound to secure the magnets to a laminate or lamination increases thermal conduction and provides a structural load path through the magnets compared to alternative magnet securing methods.

[0019] The solution described herein allows for retaining the molded compound without the use of conductive materials. When the molded compound is injected under pressure, the embodiment of the deformable gasket creates a seal, thereby providing containment of the molded compound. When a non-conductive insert (e.g., a dovetail insert, a connector, or a coupler) is used in the center bridge position to support the load on the rotor during operation and when a non-conductive gasket is used instead of a conventional outer bridge, there is no conductive leakage path where flux loss may occur around the magnet. Therefore, the proposed solution allows for a significant reduction in magnet utilization at a given performance specification, thereby enhancing pricing metrics and reducing dependence on heavy rare earth elements.

[0020] Beyond the primary objectives of the solution described herein, the proposal has the ancillary benefits of compatibility with alternative magnet configurations, the ability to be versatile in material selection, and can be used with a central bridge (e.g., a bridge within a laminate or lamination extending between the lower ends of a recess within a pair of recesses that receive a magnet) present and only outer bridges (e.g., bridges within a laminate or lamination extending between the upper ends of a recess that receives a magnet and the outer periphery of a magnet or laminate) have been eliminated. Thus, the flexibility of the solution described herein demonstrates a great degree of utilization in implementing the use of a molding compound while eliminating bridges within a laminate or lamination.

[0021] refer to Figures 1 to 3 , a rotor 10 for an electric machine is shown. The rotor 10 includes a core 12 formed of a plurality of stacked plates 14. The plates 14 may be referred to as a plurality of laminations or laminates, which are stacked in sequence in an axial direction along an axis of rotation 16 of the rotor 10 of the electric machine. The laminations are each made of a material such as iron or steel, such as electrical steel. The laminations are then aligned in an axial direction (i.e., along the axis of rotation 16 of the rotor 10) to form the rotor 10 of the electric machine. Depending on the desired application, the laminations may be "loosely" stacked, welded, or bonded together. The laminations may include a thin layer of insulating material (e.g., a thin epoxy or resin layer having a thickness of about 0.001 mm). If the application requires that adjacent laminations be fixed to each other (i.e., via welding or bonding), there may or may not be a small space between adjacent laminations where the adjacent laminations are not fixed to each other.

[0022] The core 12, or more specifically the floor 14, may define pockets 18 arranged in V-shaped pairs. The V-shaped pairs may be arranged in one or more groups of pockets 18 that each form a magnetic pole of the rotor 10. In the example shown, each pole has two pairs of V-shaped pockets 18 aligned on a common D-axis 20. However, it should be understood that each pole may define any number of pairs of V-shaped pockets 18. The core 12, or more specifically the floor 14, may also define a notch 22 extending from an outer end 24 of each pocket 18 to an outer periphery 26 of the plate 14. The core 12, or more specifically the floor 14, may also define a bridging cavity 28 extending between and connecting the inner ends 30 of each pocket 18 within each pair of the pairs of V-shaped pockets 18. The bridging cavity 28 may also be referred to as a connecting cavity or cavity. The recess 22 corresponds to the space where the outer bridge of the plate 14 (i.e., the bridge between each recess 18 and the outer periphery of the plate 14) has been removed, and the bridging cavity 28 corresponds to the space where the inner bridge of the plate 14 (i.e., the bridge between each recess 18 within the pair of V-shaped recesses 18) has been removed.

[0023] A magnet 32 ​​is disposed within each of the pockets 18. An insert, connector, or coupler 34 is disposed within each of the bridge cavities 28. The coupler 34 secures an outer portion 36 of each plate 14 to a base portion 38 of each plate 14. Each outer portion 36 of each plate 14 is separated from a corresponding base portion 38 of each plate 14 by an opening formed by one of the paired V-shaped pockets 18, two of the notches 22, and one of the bridge cavities 28. In the event that each plate has more than one paired V-shaped pockets 18, an additional outer portion 40 of each plate 14 may be indirectly connected to the base portion 38 of each plate through one of the outer portions 36. In such an alternative, the outer portion 36 may be referred to as an intermediate portion.

[0024] A molding compound 42 is disposed within each pocket 18 and each bridge cavity 28. The molding compound 42 may be an epoxy or resin that secures the magnets 32 to the board 14, increases thermal conduction, and provides a structural load path through the magnets 32. The molding compound 42 encapsulates each magnet 32 ​​and each coupler 34. The molding compound 42 also secures each magnet 32 ​​and each coupler 34 to at least one of the boards 14.

[0025] The gasket 44 is disposed along the outer end 24 of each recess 18. In other words, each gasket 44 can be disposed between one of the recesses 18 and one of the recesses 22. The gasket 44 is configured to retain the molded material 42 within the recess 18 and the bridge cavity 28. The gasket 44 is also configured to isolate the molded material 42 from the recess 22. In other words, the gasket 44 is configured to prevent the molded material 42 from escaping from the recess 18 and entering the recess 22, particularly during manufacturing when the molded material 42 is still in liquid form before curing into a solid. The plate 14 defines an undercut or slot 46 configured to receive the gasket 44. Each slot 46 can be defined between the outer end 24 of one of the recesses 18 and one of the recesses 22.

[0026] The washer 44 can have one of several configurations. For example, the washer 44 can have a C-shaped or U-shaped cross-section that engages the outer end 48 and lateral side 50 of the magnet 32 ​​(see, e.g., Figures 1 to 3 ), which serves to center the magnet 32 ​​in the corresponding recess 18. As another example, the washer 44 may have a flat cross-section that only engages the outer end 48 of the magnet 32 ​​(see, for example, Figure 4 ).

[0027] The shape of the connector 34 can be dovetail-shaped. The connector 34 can engage the corresponding dovetail recess 52 defined by the outer portion 36 and the base portion 38 of each plate 14 to fix the outer portion 36 to the corresponding base portion 38. The connector 34, the gasket 44 and the molding compound can all be made of non-conductive materials to reduce magnetic flux leakage around the magnet 32. For example, the molding compound 42 can be made of a non-conductive epoxy or resin. The connector 34 can be made of a non-conductive material (such as a hard plastic or rigid plastic) that provides structural support. The gasket 44 can be made of a non-conductive material that also provides the necessary sealing properties to prevent the molding compound from flowing into the recess 22 during manufacturing. For example, the gasket can be made of a rubber or soft plastic material that has sufficient elasticity to fill any existing gaps where the molding compound may flow out of the cavity 18 and flow into the recess 22 during manufacturing.

[0028] Reference now Figure 5 and Figure 6 , a stator 54 is shown. The stator 54 has teeth 56 and stator winding cavities or slots 58 to support a set of stator windings. The stator 54 can surround a rotor 10 having multiple rotor sections from any of the embodiments described herein having permanent magnet pockets arranged therein. Some portions are not shown. The difference between the pole arc angles can be equal to the slot pitch 60 of the stator. The slot pitch 60 is the mechanical angle between adjacent slots arranged around the entire stator 54. For example, a 48-slot stator 54 has a slot pitch 60 of 7.5 degrees. The difference between the pole arc angles can be equal to the slot pitch 60 of the stator 54.

[0029] It should be understood that the first, second, third, fourth, etc. markings for any component, state or condition described herein can be rearranged in the claims so that they are arranged in chronological order with respect to the claims. In addition, it should be understood that if one or more specific components, states or conditions are claimed, any component, state or condition described herein without a numerical name can be given a first, second, third, fourth, etc. name in the claims.

[0030] The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments may be combined to form additional embodiments that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it should be recognized by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve the desired overall system properties, depending on the specific application and implementation. Thus, embodiments that are described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of the present disclosure and may be desirable for a particular application.

[0031] According to the present invention, there is provided a motor rotor having: a plurality of plates stacked along an axis, each of the plates defining a pair of recesses, a notch extending from an outer end of each recess to an outer periphery of the plate, a bridge cavity extending between and connecting the inner ends of each recess in each pair of the recesses; a magnet disposed in each of the recesses; and a coupler disposed in each of the bridge cavities and fixing an outer portion of each plate to a base portion of each plate, wherein each outer portion of each plate is connected to the base portion of each plate through an opening. Partially separated, the opening is formed by a pair of the paired recesses, two of the recesses and one of the bridge cavities; a molded material disposed in each recess and each bridge cavity, wherein the molded material (i) encapsulates each magnet and each connector, and (ii) secures each magnet and each connector to at least one of the plates; and a gasket, each of which is disposed along an outer end of each recess, wherein the gasket is configured to (i) retain the molded material in the recess and the bridge cavity, and (ii) isolate the molded material from the recess.

[0032] According to an embodiment, each of the plates defines a slot configured to receive the gasket.

[0033] According to an embodiment, said slot is defined between said outer end of each pocket and the corresponding notch.

[0034] According to an embodiment, the washer has a flat cross section engaging an outer end of the magnet.

[0035] According to an embodiment, the washer has a C-shaped cross-section engaging the outer end and lateral sides of the magnet.

[0036] According to an embodiment, the washer has a U-shaped cross-section engaging the outer ends and lateral sides of the magnet.

[0037] According to an embodiment, the coupler is dovetail shaped and engages corresponding dovetail recesses defined by the outer portion and the base portion of each plate to secure the outer portion to the corresponding base portion.

[0038] According to an embodiment, the connector and the molding compound consist of a non-conductive material.

[0039] According to the present invention, there is provided a motor rotor having: a core, the core defining: (i) pockets; (ii) notches extending from the outer end of each pocket; and (iii) cavities, each of which extends between the inner ends of two of the pockets and connects the two pockets; a magnet, the magnet being disposed in each of the pockets; a resin, the resin being disposed in each pocket and each cavity, wherein the resin (i) encapsulates each magnet and (ii) fixes each magnet to the core; and washers, the washers being respectively disposed along the outer end of each pocket, wherein the washers are configured to (i) retain the resin in the pocket and the cavity, and (ii) isolate the resin from the notches.

[0040] According to an embodiment, the present invention is also characterized by a connector, which is arranged in each of the cavities and fixes the outer part of the core to the base part of the core, wherein each outer part is separated from the base part by an opening, and the opening is formed by two of the recesses, two of the recesses and one of the cavities.

[0041] According to an embodiment, the core defines a slot configured to receive the gasket.

[0042] According to an embodiment, said slot is defined between said outer end of each pocket and the corresponding notch.

[0043] According to an embodiment, the washer has a flat cross section engaging an outer end of the magnet.

[0044] According to an embodiment, the washer has a cross-section engaging an outer end and a lateral side of the magnet.

[0045] According to an embodiment, the resin consists of a non-conductive material.

[0046] According to the present invention, there is provided a motor rotor having: stacked plates, the stacked plates defining: (i) pockets; (ii) recesses extending from the outer end of each pocket to the outer periphery of the plate; and (iii) connecting cavities, each connecting cavity extending between the inner ends of two of the pockets and connecting the two pockets; a magnet disposed in each of the pockets; a connector disposed in each of the connecting cavities and fixing the outer portion of the plate to the base portion of the plate; a resin disposed in each pocket and each cavity, wherein the resin (i) encapsulates each magnet and connector and (ii) fixes each magnet and connector to at least one of the plates; and washers, each of the washers being disposed between one of the pockets and one of the recesses, wherein the washers are configured to (i) retain the resin in the pockets and the cavity, and (ii) isolate the resin from the recesses.

[0047] According to an embodiment, the plate defines a slot configured to receive the gasket.

[0048] According to an embodiment, the washer has a flat cross section engaging an outer end of the magnet.

[0049] According to an embodiment, the washer has a cross-section engaging an outer end and a lateral side of the magnet.

[0050] According to an embodiment, the connector and the molding compound consist of a non-conductive material.

Claims

1. A motor rotor, comprising: A plurality of plates stacked along an axis, each of the plates defining Pairs of recesses, a notch extending from an outer end of each pocket to an outer periphery of the plate, a bridging cavity extending between and connecting the inner ends of each recess in each of the pairs of recesses; a magnet disposed within each of the pockets; a coupler disposed within each of the bridging cavities and securing an outer portion of each panel to a base portion of each panel, wherein each outer portion of each panel is separated from the base portion of each panel by an opening formed by one of the pairs of recesses, two of the notches, and one of the bridging cavities; a molding compound disposed within each pocket and each bridge cavity, wherein the molding compound (i) encapsulates each magnet and each coupler and (ii) secures each magnet and each coupler to at least one of the plates; as well as A gasket is disposed along an outer end of each recess, wherein the gasket is configured to (i) retain the molded material within the recess and the bridging cavity, and (ii) isolate the molded material from the recess. 2 . The electric machine rotor of claim 1 , wherein each of the plates defines a slot configured to receive the washer. 3 . The electric machine rotor of claim 2 , wherein the slot is defined between the outer end of each pocket and a corresponding notch. 4 . The electric machine rotor of claim 1 , wherein the washer has a flat cross-section that engages an outer end of the magnet. 5 . The electric machine rotor of claim 1 , wherein the washer has a C-shaped cross-section engaging an outer end and a lateral side of the magnet. 6 . The motor rotor of claim 1 , wherein the washer has a U-shaped cross-section engaging an outer end and a lateral side of the magnet.

7. The electric machine rotor of claim 1 wherein the coupler is dovetail shaped and engages corresponding dovetail recesses defined by the outer portion and the base portion of each plate to secure the outer portion to the corresponding base portion.

8. The electric machine rotor of claim 1, wherein the coupler and the molding compound are composed of a non-conductive material.

9. A motor rotor, comprising: A core defining: (i) a pocket; (ii) a notch extending from an outer end of each recess; and (iii) cavities, each cavity extending between inner ends of two of the recesses and connecting the two recesses; a magnet disposed within each of the pockets; a resin disposed within each pocket and each cavity, wherein the resin (i) encapsulates each magnet and (ii) secures each magnet to the core; as well as A gasket is disposed along an outer end of each recess, wherein the gasket is configured to (i) retain the resin within the recess and the cavity, and (ii) isolate the resin from the recess.

10. The electric machine rotor of claim 9, further comprising a coupling disposed within each of the cavities and securing an outer portion of the core to a base portion of the core, wherein each outer portion is separated from the base portion by an opening formed by two of the pockets, two of the recesses, and one of the cavities.

11. The electric machine rotor of claim 9, wherein the core defines a slot configured to receive the washer, and wherein the slot is defined between the outer end of each pocket and a corresponding notch. 12 . The electric machine rotor of claim 9 , wherein the washer has a flat cross-section that engages an outer end of the magnet.

13. The electric machine rotor of claim 9, wherein the washer has a cross-section that engages an outer end and a lateral side of the magnet.

14. A motor rotor, comprising: A stack of plates, the stack of plates defining: (i) a recess; (ii) a notch extending from the outer end of each recess to the outer periphery of the plate; and (iii) connecting cavities, each connecting cavity extending between inner ends of two of the recesses and connecting the two recesses; a magnet disposed within each of the pockets; a connector disposed within each of the connection cavities and securing an outer portion of the board to a base portion of the board; a resin disposed within each pocket and each cavity, wherein the resin (i) encapsulates each magnet and connector and (ii) secures each magnet and connector to at least one of the plates; as well as Gaskets are each disposed between one of the pockets and one of the recesses, wherein the gaskets are configured to (i) retain the resin within the pockets and the cavity, and (ii) isolate the resin from the recesses.

15. The electric machine rotor of claim 14, wherein the plate defines a slot configured to receive the washer.

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