Permanent magnet motor with sleeve

Abstract

To provide a permanent magnet motor that reduces magnetic flux leakage compared to conventional designs. [Solution] The electric motor assembly may include a rotor coaxially mounted on a shaft. This rotor may include a central stack mounted on a balance ring. The central stack may have slots along its outer circumference that hold pole pieces attached to a plurality of magnets. Each magnet may be positioned between the pole piece and the central stack. Each magnet may not be completely surrounded by the metal body of the rotor. The rotor components described may be enclosed within a winding fiber sleeve. The rotor is rotatably mounted within a stator.

Description

Technical Field

[0001] The present disclosure relates to an electric motor, and more particularly to the configuration of a rotor in an electric motor.

Background Art

[0002] In recent years, there has been a dramatic increase in the trend to design and build on-road and off-road vehicles with low fuel consumption, low emissions, or zero emissions, and the development of hybrid and all-electric vehicles has been highly regarded. Therefore, electric motors have come to be emphasized, either as the sole power source for propulsion (e.g., in all-electric vehicles) or as a secondary power source for propulsion in a compound propulsion system (e.g., in hybrid vehicles or dual electric motor vehicles). In electric motors for such applications, either an AC or DC permanent magnet motor design or an AC induction motor design can be utilized. Regardless of the type of electric motor, the motor is generally designed to achieve a desired efficiency, torque density, or high-speed output for a particular application, with acceptable motor dimensions and weight.

Summary of the Invention

[0003] This disclosure relates to an electric motor. An electric motor assembly includes a rotor mounted coaxially to a shaft. In one embodiment, the rotor may include a central stack mounted to a balance ring. The central stack may have slots along its outer circumference for holding pole pieces (magnetic pole pieces) coupled with a plurality of magnets. Each magnet may be positioned between the pole piece and the central stack. In one embodiment, the pole pieces may further include fixing slots, and a plurality of embedded positioning dowels protruding from the surface of the balance ring may allow the pole pieces to be secured during the sleeve winding process. In one embodiment, the rotor components described are enclosed within a winding fiber sleeve (covering material) that holds the pole pieces in place around the rotor. The rotor is rotatably mounted within a stator to form a permanent magnet motor. [Brief explanation of the drawing]

[0004] [Figure 1] This is an exemplary axial partial cross-sectional view of an electric motor according to a particular embodiment of the present disclosure.

[0005] [Figure 2] This is a perspective view of a rotor with a sleeve according to a particular embodiment of the present disclosure.

[0006] [Figure 3] This is a perspective view of a rotor component housed within a rotor sleeve according to a particular embodiment of the present disclosure.

[0007] [Figure 4] This is an exemplary axial view of a sleeved rotor according to a particular embodiment of the present disclosure.

[0008] [Figure 5A] This is an exploded view of the internal components of a rotor according to a specific embodiment of the present disclosure.

[0009] [Figure 5B] This is a perspective view of a balance ring and stacked assembly on a motor shaft according to a specific embodiment of the present disclosure.

[0010] [Figure 6] This is a transverse cross-sectional view of a rotor according to a particular embodiment of the present disclosure.

[0011] [Figure 7] The motor performance graphs shown here compare motor speed to torque for both conventional permanent magnet motors and permanent magnet motors with carbon sleeves, according to specific embodiments of this disclosure. [Modes for carrying out the invention]

[0012] Each embodiment relates to a permanent magnet motor comprising a rotor having magnetic pieces arranged on its outer circumference, with a winding fiber sleeve used on its outer circumference to hold the magnetic pieces in place. For example, the winding fiber sleeve can be made of carbon fiber or other fibrous material. In one embodiment, the magnetic pieces are not held within the rotor using metal components, and the magnets are not completely enclosed within the rotor. The magnetic field generated by the stator acting on the magnetic pieces within the rotor can be stronger compared to a conventional rotor in which the magnetic pieces are embedded in metal. This is because the winding fiber sleeve eliminates metal components, resulting in a lower level of interference with the magnetic field generated by the stator. In one embodiment, metal components positioned between the magnetic pieces and the central portion of the rotor are limited or absent. Thus, the permanent magnet motors disclosed herein can provide improved performance compared to conventional designs because magnetic flux leakage is reduced.

[0013] Figure 1 shows an axial cross-sectional view of a permanent magnet motor 100 according to one embodiment of the present disclosure. The diagram shown in Figure 1 is simplified for illustrative purposes, and windings and other components are omitted in this diagram. As shown, the rotor 101 is surrounded by a stator 103. Multiple windings (not shown) are arranged around each stator tooth 109. In various embodiments, these windings are made of copper, but other materials are also within the scope of the present invention. The windings define multiple poles, for example, a 3-phase, 4-pole design, or a 6-pole design.

[0014] As shown in the figure, the rotor 101 is surrounded by the stator 103, and the two are separated by an air gap 105. A shaft 107 is coupled to the rotor 101, and this shaft 107 provides a means for coupling the motor 100 to various devices and mechanisms such as axles and gearboxes in an electric vehicle. The air gap 105 between the stator 103 and the rotor 101 is sized to obtain a desired level of magnetic inductance from the stator 103 to the rotor 101. The air gap 105 can also affect the saturation level and harmonic level of the magnetic flux adjacent to the air gap 105. Generally, the smaller the air gap 105, the stronger the magnetic flux between the stator 103 and the rotor 101.

[0015] As shown in the figure, a series of magnets 111A and 111B are arranged around the rotor 101 in a "V" shape. The configuration of magnets 111A and 111B is such that they have a top end 117 facing the shaft 107 and two arm portions 119A and 119B facing the stator 103. The ends of each arm portion 119A and 119B are adjacent to openings 120A and 120B that provide space between the arm of each magnet and the air gap 105. This air pocket or space provides magnetic flux from the rotor to the stator, minimizing the magnetic flux loss of the permanent magnets. The magnets 111A and 111B are not embedded in the solid metal body of the rotor 101. This figure is only one example of how magnets 111A and 111B may be oriented, and it should be understood that in other embodiments, magnets 111A and 111B may be arranged differently. A winding fiber sleeve 115 is shown surrounding the rotor to hold magnets 111A and 111B in place as the rotor 101 rotates within the stator 103. It should be understood that even in other magnet configurations where each magnet is not completely surrounded by the rotor, the loss of magnetic flux of the permanent magnets can be reduced.

[0016] Figure 2 shows the assembled rotor 101 according to the present invention. The rotor 101 is enclosed within a winding fiber sleeve 115, in contrast to conventional iron bridges. A shaft 107 is coupled to the rotor 101, providing a means for coupling the motor to various devices and mechanisms in an electric vehicle, such as axles and gearboxes. In some embodiments, the winding fiber sleeve 115 is made of carbon fiber that is wound around the rotor under pretension. In one embodiment, the sleeve has a thickness of 0.1 mm to 2 mm. In other embodiments, the sleeve has a thickness of 0.3 mm, 0.4 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. Unlike existing methods for manufacturing winding fiber rotor sleeves, the method for manufacturing the winding fiber sleeve of the present invention attempts to minimize the sleeve thickness by applying relatively high tension to the fibers during the winding process. To minimize the sleeve thickness, the fibers can be wound around the rotor under pretension. In some embodiments, the fibers can be wound using a specific godet device that has a godet roll capable of winding the fibers around a rotor under tension while minimizing damage to the fibers.

[0017] Figure 3 shows an exemplary embodiment of the fully assembled internal components of the rotor 101 (with the sleeve removed) according to the present disclosure. The rotor 101 surrounds the shaft 107 and comprises a lower end balance ring 313, a central stack 305, pole pieces 307, and magnets 111A and 111B. The shaft 107 has a coaxial disk 315 protruding from the lower end of the shaft 301. The coaxial disk 315 has one or more flat segments ("flat sections") 303 along its outer circumference. The flat sections 303 function as gripping areas for a filament winding device during the manufacturing of the rotor, specifically during the sleeve winding process in which the filament winding device grips the shaft and rotates the rotor. In some embodiments, the disk may not have flat sections 303 and may instead have other gripping mechanisms suitable for a filament winding device. In some embodiments, the disc may not have a flat portion or any other gripping mechanism, and as a result, the disc has a continuous outer circumference. In this figure, it is not shown that the winding fiber sleeve surrounds the rotor 101.

[0018] Continuing to refer to Figure 3, the central stacked structure 305 is mounted on the balance ring 313. The central stacked structure 305 has a number of slots 317 along its outer edge, which extends along the entire length of the central stacked structure 305. A number of magnets 111 are coupled to each pole piece 307. During assembly, the pole pieces 307 and magnets 311 are fitted into the slots 317 of the central stacked structure 305 such that the magnets 111 are pressed between the pole piece 307 and the central stacked structure 305. This can be seen more clearly by referring to Figure 5 below. Note that in some embodiments, the pole pieces 307 and the central stacked structure 305 are not connected by a steel bridge or other metal parts, as in conventional rotor designs. Eliminating all metal connections between the pole pieces 307 and the central stacked structure 305 reduces magnetic flux leakage through the connections.

[0019] In some embodiments, each pole piece 307 has a fixing slot 309 configured to interlock with a positioning dowel (not shown) in a balance ring. The fixing slot 309 and positioning dowel can function as a fixing mechanism during the manufacturing of the rotor. In some embodiments, the magnet 111, pole pieces 307, and central stack 305 are fixed to each other during assembly. In such embodiments, the pole pieces 307 do not have fixing slots 309. At high speeds under which the rotor components rotate during the sleeve winding process, this fixing mechanism can keep the pole pieces 307 in close proximity to the central stack 305 during manufacturing.

[0020] In one embodiment, the sleeve winding process begins by positioning the rotor shown in Figure 3 on a rotating mechanism connected to a filament tensioning device, such as a godet roll. For example, this tensioning device may include a spool of carbon fibers that pass through a tank of epoxy resin and are then wound around the outer circumference of the rotor mechanism shown in Figure 3 as it rotates in one direction. In another embodiment, the tensioning device may coat the resin onto the spool during the feeding process. This system makes it possible to wind the sleeve in a predetermined pattern and with a predetermined number of fiber coverings along the length of the rotor to create a specific thickness of sleeve.

[0021] It should be understood that the sleeve surrounding the rotor does not necessarily have to be made of carbon fiber. Other similar materials can also be wrapped around the rotor and used to surround the rotor and maintain the positions of the pole pieces and magnets. For example, other composite materials made from other types of fibers such as ceramics, glass fibers, polypropylene, polyethylene, polyether ether ketone (PEEK), and similar plastics can be embedded in a resin to form a durable material that can be used to form a sleeve that applies tension around the rotor. In a further embodiment, combinations of materials such as carbon fibers embedded in a plastic can be used to make the sleeve.

[0022] Figure 4 is an axial cross-sectional view of a fully assembled rotor according to the present disclosure. This assembly is coaxial with a shaft 107, as indicated by the shaft 107 passing through the center of the rotor. Looking axially, it can be seen that magnets 111A and 111B are pressed against the same plane with respect to both pole pieces 307 and the central laminated stack 305. In some embodiments, magnets disposed on adjacent faces of the pole pieces (e.g., pairs of magnets forming a "V" shaped configuration) are separated from each other by an air gap. Each pole piece 307 can include a fixing slot 309 that engages a positioning dowel so that the pole piece 307 is fixed during the winding process. The winding fiber sleeve 115 can wrap around the entire assembly. Of course, this positioning dowel is not essential, and it should be understood that motor embodiments may not include a positioning dowel or rod.

[0023] FIG. 5A shows a partial assembly of the rotor 101 according to the present disclosure. In this partial assembly, only the central laminated stack 305 and the balance ring 313 are attached to the shaft 107. As shown, the positioning dowels 507 are embedded in the balance ring 313 and protrude beyond the surface of the balance ring 313. A series of positioning dowels 507 can protrude a small distance from the surface of the balance ring 313 that contacts the central laminated stack 305.

[0024] FIG. 5B shows an exploded view of the internal assembly of the rotor according to the present disclosure. FIG. 5B shows how the pole pieces 307, and the magnets 111A and 111B can fit into the plurality of slots 317 and be coupled to each other and to the central laminated stack 305. As shown, in some embodiments, the magnets 111A and 111B are fixed to the pole pieces 307 as shown in FIG. 5B, but not to the central laminated stack 305. In one embodiment, the length of each pole piece 307 is the same as the length of the central laminated stack 305. Each pole piece 307 can be coupled to two magnets, 111A and 111B, of similar length. In other embodiments, the magnets 111A and 111B can be made shorter and more magnets 111A and 111B can be used to occupy the length of the pole pieces 307 to which they are coupled. In yet other embodiments, the magnets 111A and 111B may be of a shape different from the rectangular prisms shown in FIG. 5B.

[0025] Continuing to refer to Figure 5B, each pole piece 307 may have a fixing slot 309 for securing the pole piece 307 to the balance ring 313. In one embodiment, the fixing slot 309 penetrates the entire length of the pole piece 307. In other embodiments, the fixing slot 309 may terminate in the middle of the pole piece 307. In embodiments in which the rotor includes two balance rings at each end of the central stacked stack 305, the pole piece 307 may have one fixing slot 309 extending along the length of the pole piece 307. Alternatively, the pole piece 307 may have one fixing slot 309 at each end of the pole piece 307, with each fixing slot 309 terminating within the length of the pole piece 307. As described herein, in some embodiments, the pole pieces 307, magnets 111A and 111B, and the central stacked stack 305 can be fixed to each other during manufacturing, and as a result, the assembly does not have fixing slots 309 or positioning dowels 507.

[0026] Figure 6 shows one side of a lateral cross-section of the rotor according to this disclosure. Corresponding to the components that radiate outward from the shaft 107, Figure 6 shows the central stacked stack 305, the magnet 111A coupled to the pole piece 307, and the positioning dowel 507 that engages with the fixing slot 309 of the pole piece 307. The entire assembly is mounted to the balance ring 313. This figure shows how the positioning dowel 507 is embedded in the balance ring 313 and protrudes only from the surface of the balance ring 313 that contacts the rotor assembly.

[0027] Figure 7 compares the torque generation of the disclosed sleeved motor with that of a conventional permanent magnet motor. The solid line 701 records the amount of torque generated by the disclosed sleeved motor at various speeds. The dotted line 703 represents the torque generated by a conventional permanent magnet motor at the same speed. As shown in the figure, the sleeved motor can generate more torque than the conventional motor at the same speed. The sleeved motor can have a higher maximum torque because it allows for a larger fundamental wave flux by eliminating ribs and bridges.

[0028] Sleeved motors can also generate more power than conventional motors at the same speed. A higher ratio of fundamental flux to harmonic flux in the slots results in higher motor efficiency at high speeds and at both low and high torque conditions. Furthermore, carbon-coated motor designs can reduce or eliminate flux leakage, allowing for better utilization of inverter current and resulting in a maximum power increase of up to 25% or more. At high speeds, sleeved motors can generate more power compared to conventional motors without increasing the amount of permanent magnets used.

[0029] The foregoing disclosure is not intended to limit the disclosure to the exact form or specific field of use disclosed. Therefore, various alternative embodiments and / or modifications to the disclosure, whether expressly described or implied herein, are possible in light of the disclosure. Having described embodiments of the disclosure in this manner, those skilled in the art will recognize that changes in form and detail can be made without departing from the scope of the disclosure. Therefore, the disclosure is limited only by the claims.

[0030] The above specification has described the disclosure with reference to specific embodiments. However, as those skilled in the art will understand, the various embodiments disclosed herein can be modified or implemented in various other ways without departing from the spirit and scope of the disclosure. Therefore, this description should be considered illustrative and is intended to teach those skilled in the art how to manufacture and use various embodiments of the disclosed motor assemblies. It should be understood that the forms of disclosure shown and described herein should be interpreted as representative embodiments. Equivalent elements, materials, processes, or steps can be substituted with those representatively shown and described herein. Furthermore, certain features of the disclosure can be used independently of the use of other features, as will be apparent to those skilled in the art who are familiar with the merits of this description of the disclosure. Expressions such as “including,” “comprising,” “incorporating,” “consisting of,” “have,” and “is” used to describe and claim the disclosure are intended to be interpreted in a non-exclusive manner, meaning that there may be items, components, or elements that are not expressly described. References to the singular form should be interpreted as also relating to the plural form.

[0031] Furthermore, the various embodiments disclosed herein should be interpreted in an illustrative and descriptive sense and not in any way be construed as limiting the disclosure. All references to joining (e.g., “attached,” “affixed,” “coupled,” “connected,” etc.) are used solely to aid the reader’s understanding of the disclosure and do not imply any limitation, particularly with respect to the location, orientation, or use of the systems and / or methods disclosed herein. Accordingly, where there are references to joining, they should be interpreted broadly. Moreover, such references to joining do not necessarily mean that the two elements are directly connected to each other.

[0032] Furthermore, all numerical terms, including but not limited to "first," "second," "third," "primary," "secondary," "main," or any other common terms and / or numerical terms, should also be interpreted solely as identifiers to aid the reader's understanding of the various elements, embodiments, variations, and / or modifications of this disclosure, and in particular, they should not impose any restrictions on the order or priority of any element, embodiment, variation, and / or modification, or any other element, embodiment, variation, and / or modification, or beyond.

[0033] It should be understood that one or more of the elements shown in the drawings / figures may be implemented in a more separated or more integrated manner to be useful for a particular application, or in certain cases, may even be removed or abandoned as non-functional. Furthermore, any hatched areas in the drawings / figures should be considered illustrative only and not limiting unless otherwise specified.

Claims

1. It is an electric motor, A stator configured to generate a magnetic field and receive the rotor into a central opening, An electric motor comprising: a rotor sized to fit into the central opening, wherein the rotor comprises a plurality of magnets, the rotor is covered on its outer circumference with a winding fiber sleeve, and the magnets are not completely surrounded by the rotor.

2. The electric motor according to claim 1, wherein the rotor comprises a centrally located shaft having a first end and a second end, and the first end of the shaft comprises a radially projecting disc.

3. The electric motor according to claim 2, wherein the outer circumference of the disk is continuous via a plurality of flat edges.

4. The electric motor according to claim 2, further comprising a balance ring adjacent to the first end of the shaft and a plurality of positioning dowels within the balance ring.

5. The electric motor according to claim 4, wherein the positioning pin is embedded in a circular pattern concentric with the balance ring.

6. The electric motor according to claim 1, wherein the plurality of magnets are coupled to a plurality of pole pieces such that each pole piece is coupled to at least two magnets.

7. The electric motor according to claim 6, wherein each of the pole pieces engages with a plurality of slots in the central stacked stack such that the plurality of magnets are oriented between the inner edge of the pole piece and the outer edge of the central stacked stack.

8. The electric motor according to claim 7, further comprising a plurality of positioning dowels that penetrate the rotor via fixing slots on the edges of each pole piece.

9. The electric motor according to claim 1, wherein the winding fiber sleeve includes a winding carbon fiber sleeve.

10. The electric motor according to claim 1, wherein there is a space between each end of the plurality of magnets and the winding fiber sleeve.

11. A method for assembling a rotor for an electric motor, The steps include inserting a magnetic piece into a slot on the outer circumference of the rotor holder, The steps include: positioning the magnetic piece on the rotor fixing device using a positioning pin, A step of applying tension to non-metallic fibers on a filament winding machine, A method comprising the step of winding the non-metallic fibers under tension around the rotor in order to hold the magnetic piece in a predetermined position on the rotor fixture.

12. The method according to claim 11, further comprising the step of fixing a filament winding device to a plurality of flat edges along the outer circumference of a disc at one end of the rotor holder in order to apply tension to the nonmetallic fibers.

13. The method according to claim 11, wherein the step of positioning the magnetic piece using a positioning dowel includes the step of fixing the magnetic piece to the same surface as the surface of the rotor fixing device.

14. A method for assembling a rotor for an electric motor, The steps include inserting magnetic pieces into slots on the outer periphery of the stacked structure, A method comprising the step of winding non-metallic fibers under tension around the rotor in order to hold the magnetic piece in a predetermined position within the slot.

15. The method according to claim 14, further comprising the step of engaging the magnetic piece with a positioning dowel of a rotor fixture.

16. The method according to claim 14, further comprising the step of fixing the magnetic piece to the stacked stack.

17. In order to wrap the aforementioned nonmetallic fibers, The steps include fixing the filament winding device to multiple flat edges along the outer circumference of the disk at one end of the rotor holder, The method according to claim 14, further comprising the step of applying tension to the non-metallic fibers on the filament winding apparatus.

Images