Rotor assembly

Abstract

The rotor assembly (10) includes a rotor support hub (12) with a plurality of first connection portions disposed around the periphery of the rotor support hub. The rotor assembly further includes a plurality of rotor segments (14), each having a second connection portion. Each of the second connection portions is cooperable with at least one of the plurality of first connection portions to connect each of the rotor segments around the periphery of the rotor support hub. A plurality of fastening portions (26) are each configured to be received between the cooperating first and second connection portions, creating an interference fit therebetween, to secure the rotor segment to the rotor support hub. The rotor support hub may be constructed from a plurality of thin plates.

Description

Technical Field

[0001] The present invention relates to a rotor assembly. More particularly, but not by way of limitation, the present invention relates to an electromechanical rotor assembly, an electromechanical machine, and a vehicle comprising the electromechanical machine.

Background Art

[0002] It is becoming increasingly common to use an electromechanical machine to generate a traction force for propelling a vehicle, such as a hybrid electric vehicle (HEV) or an electric vehicle (EV). Permanent magnet motors can provide the high power density and high efficiency suitable for these applications. However, these characteristics rely on the use of high energy density permanent magnets (which reduce the required level of electrical loading and associated winding losses for a given power density). Permanent magnets made from rare earth elements such as neodymium iron boron (NdFeB) have high power density and good demagnetization resistance. However, this type of permanent magnet is relatively expensive, has historically experienced price increases, and is said to have a significant environmental footprint. As a result, if new motors with sufficient levels of power density, efficiency, and demagnetization resistance are developed, the use of magnets containing little or no rare earth elements, such as ferrite magnets, would be desirable in at least some applications.

[0003] A two-piece part, namely a spoke-type rotor having a plurality of ferromagnetic poles arranged around a central non-magnetic support hub, provides a rotor topology suitable for the development of the required new motor. (A relatively high level of output density can be obtained by the non-magnetic central support, and the structural integrity of the rotor required for high-speed operation is ensured.) However, such a two-piece rotor usually incurs additional costs due to additional rotor components and measures necessary to connect the rotor poles to the central support to each other. These components are usually fabricated by a high-precision machining process to ensure sufficient connection between them. This machining is relatively expensive and undesirable as it minimizes the cost competitiveness versus performance of the two-piece rotor. It is also possible to fabricate these components using a relatively inexpensive extrusion process. However, materials suitable for use in the extrusion process and providing good rotor characteristics, such as copper-beryllium alloys, are unduly expensive. The present invention has been devised in view of such circumstances.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] An object of an embodiment of the present invention is to at least mitigate one or more of the problems associated with well-known configurations.

MEANS FOR SOLVING THE PROBLEMS

[0005] According to a first aspect of the present invention, there is provided an electric machine rotor assembly comprising: a rotor support hub having a plurality of first connection portions disposed around the rotor support hub; a plurality of rotor segments each having a second connection portion, each of the second connection portions being adapted to cooperate with at least one of the plurality of first connection portions to connect each of the rotor segments around the rotor support hub; and a plurality of fixing portions, each of the fixing portions being configured to be received between the first and second connection portions that cooperate with each other to fix the rotor segment to the rotor support hub and to cause an interference fit therebetween. By using the fixing portions to fix the rotor segments to the rotor support hub, the need to fabricate the rotor support hub and / or the rotor segments using high-precision machining processes is eliminated.

[0006] In some embodiments, at least one of the first connection portions or at least one of the second connection portions may comprise a recess configured to receive at least one of the plurality of fixing portions. This recess facilitates the insertion of the fixture at an optimal position relative to the first connection portion, the second connection portion, or both.

[0007] Optionally, at least one of the fixing portions may be a pin. Additionally or alternatively, at least one of the fixing portions may be non-magnetic and / or at least one of the fixing portions may be made of or include a polymeric material. Additionally or alternatively, at least one of the fixing portions may be made of or include a fiber-reinforced material.

[0008] In some embodiments, at least one of the plurality of first connection portions or at least one of the plurality of second connection portions may have a contour of a camphor tree ring.

[0009] In some embodiments, the rotor support hub may be composed of a plurality of thin plates. Optionally, one or more of the plurality of thin plates may be joined to at least one other of the plurality of thin plates. Additionally or alternatively, one or more of the plurality of thin plates may be mechanically fixed, for example, clamped to at least one other of the plurality of thin plates.

[0010] The thin plates may be substantially orthogonal to an axis that will be the axis of rotation of the rotor support hub during use. Additionally or alternatively, the thin plate may be a single piece of thin plate. In some embodiments, the rotor support hub may be made of a non-magnetic material or may include a non-magnetic material. Additionally or alternatively, the rotor support hub may be made of a metallic material or may include a metallic material. In some embodiments, the thin plates may be made of a sheet material. The thin plates may be made using a punch or mold or by laser cutting.

[0011] In some embodiments, the rotor assembly may further include a plurality of permanent magnets.

[0012] According to a second aspect of the present invention, there is provided a rotor support hub for supporting a plurality of rotor segments, the rotor support hub being composed of a plurality of thin plates. In an embodiment of the present invention according to the second aspect, the rotor support hub may have any of the features described above with respect to the rotor support hub of the first aspect.

[0013] According to a third aspect of the present invention, there is provided an electromechanical rotor assembly including the aforementioned rotor support hub. The rotor support assembly may further include a plurality of rotor segments disposed around the rotor support hub.

[0014] According to a fourth aspect of the present invention, there is provided an electromechanical machine including the aforementioned rotor assembly.

[0015] According to a fourth aspect of the present invention, a vehicle including the aforementioned electromechanical device is provided. The vehicle may be an automobile, an aircraft, or a ship.

[0016] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described by way of example only.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0018] Hereinafter, with reference to the accompanying drawings, the rotor assembly 10 according to an embodiment of the present invention will be described. The rotor assembly 10 has a specific application for a driving motor used in a vehicle 100 (shown in FIG. 5). FIG. 1 shows a two-component rotor assembly 10 including a rotor support hub 12 and a plurality of rotor segments 14 (which may also be referred to as rotor poles or rotor pole segments). The rotor assembly 10 has a long axis X-X, and during use, the rotor assembly 10 rotates about this long axis. References to the radial direction in this specification are with respect to the long axis X-X.

[0019] The rotor support hub 12 occupies the central region of the rotor assembly 10 and has a generally annular contour. A central opening 16 extends straight and collinear with the major axis X-X through the center of the support hub 12. The rotor segments 14 are circumferentially spaced from each other around the radial outer periphery 12A of the rotor support hub 12 (shown best in FIG. 2). The rotor segments 14 arranged in this manner will form spokes that extend radially outward from the support hub 12. The circumferential gaps between adjacent rotor segments 14 result in a plurality of rotor slots 18. The rotor assembly 10 shown in FIG. 1 has an outer diameter of 140 mm and a stack length of 39 mm. The stack length is the dimension of the support hub 12 in the direction of the major axis X-X. Of course, other dimensions are also conceivable. This is because the exact diameter and / or stack length of the rotor support hub 12 is determined by the specifications of the rotor assembly 10, i.e., its design speed, output and / or critical rotational speed. In some embodiments, the diameter of the rotor hub 12 may be any suitable diameter between 70 mm and 280 mm. In some embodiments, the stack length may be any suitable length between 20 mm and 400 mm. In some embodiments, two or more support hubs 12 may be stacked continuously.

[0020] In this embodiment, the rotor assembly 10 further includes an output shaft 20 and a plurality of permanent magnets 22. Each of the permanent magnets 22 is attached to one of the plurality of rotor slots 18. In this embodiment, ten rotor segments 14 are provided, and thus ten rotor slots 18 and ten permanent magnets 22 are provided. Of course, it should be understood that some embodiments may have a number of rotor segments 14 other than ten, a number of rotor slots 18 other than ten, and a number of permanent magnets 22 other than ten. The permanent magnet 22 is preferably a ferrite magnet, for example, an FB9B grade ferrite magnet. However, the permanent magnet 22 may be other materials, such as rare earth magnets such as NdFeB magnets, SmCo magnets, or AlNiCo magnets. Some embodiments may not include the permanent magnet 22, for example, in an electromechanical device that depends on reluctance torque or a rotor having rotor windings.

[0021] The support hub 12 is formed of a non-magnetic material. In this embodiment, the support hub 12 is formed of non-magnetic steel. Referring to FIG. 4, the support hub 12 may be composed of a plurality of first single-piece thin plates 24 arranged in a laminated manner to form the support hub 12. It should be understood that the first thin plate 24 is arranged substantially perpendicular to the long axis X-X. Each of the first thin plates 24 has a single structure and may be formed from a sheet material, for example, using a punch or a mold or by laser cutting. In some embodiments, the first thin plate 24 is preferably made of 3% strain-hardened 316 stainless steel. In some embodiments, the first thin plate 24 is preferably made of one of the nitrogen-hardened grades of AK Steel (R) stainless steel, for example, nitrogen-hardened stainless steel 50 of AK Steel (R). Of course, other materials are also conceivable, such as non-magnetic steels and aluminum such as 302 and 304 stainless steels and 2024-T3 aluminum alloy. Each of the first thin plates 24 is preferably joined to at least one other of the first thin plates 24. Additionally or alternatively, each of the first thin plates 24 may be mechanically fixed, for example, clamped to at least one other of the first thin plates 24.

[0022] The rotor segment 14 is formed of a magnetic material. In some embodiments, each of the plurality of rotor segments 14 may be composed of a plurality of second single-piece thin sheets (not shown) arranged in a laminated configuration to form each of the rotor segments 14. In some embodiments, the rotor assembly 14 may be made of M270 - 35A non-oriented electrical steel. Of course, it should be understood that other materials may be used, such as any grade of non-oriented electrical steel. The rotor segment 14 may be made of an alloyed material in order to enhance electromagnetic performance, for example, to obtain high magnetic permeability and low hysteresis and low eddy current losses, and / or to insulate so as to minimize eddy current propagation.

[0023] The radially outer periphery 12A of the rotor support hub 12 may be configured to attach the plurality of rotor segments 14 to the rotor support hub 12. In the present embodiment, the contour of the radially outer periphery 12A is formed to provide a plurality of first connection portions 12B (best shown in FIG. 2). Further, each of the rotor segments 14 has a radially inner portion 14A. The radially inner portion 14A may be additionally or alternatively configured to attach the plurality of rotor segments 14 to the rotor support hub 12. In the present embodiment, the contour of the radially inner portion 14A is configured to provide a plurality of second connection portions 14B (best shown in FIG. 3). The first connection portion 12B may be complementary to the second connection portion 12A. The first and second connection portions 12B, 14B may each form a plurality of male connection portions and a plurality of female connection portions, or vice versa, a plurality of female connection portions and a plurality of male connection portions. The first connection portion 12B may form a first connection surface around the radially outer periphery 12A of the rotor support hub 12. Similarly, the second connection portion 12B may form a second connection surface around the radially inner portion 14A of each of the rotor segments 14.

[0024] As shown in the attached drawings, each of the plurality of first connection portions 12B may preferably include one or more first protrusions 30, and each of the second connection portions 14B may preferably include one or more first recesses 32. The first recess 32 may preferably be configured to be complementary to the first protrusion 30. Additionally or alternatively, each of the second connection portions 14B may preferably include one or more second protrusions 34, and each of the second connection portions 14B may preferably include one or more second recesses 36. The second recess 36 may preferably be configured to be complementary to the second protrusion 34. The protrusions 30, 34 may preferably extend orthogonally from the radial direction or in contact with the radial direction. Naturally, the first protrusion 30 and / or the second recess 36 may preferably form part of the radially outer periphery 12A of the rotor support hub 12. Accordingly, the first protrusion 30 and / or the second recess 36 may preferably form part of the first connection surface. The second protrusion 34 and / or the first recess 32 may preferably form part of the radially inner portion 14A of each of the rotor segments 14. Accordingly, the second protrusion 34 and / or the first recess 32 may preferably form part of the second connection surface. The aforementioned first and second connection portions 12B, 14B may sometimes be referred to as a "helicopter rotor" structure.

[0025] The first and second connectors 12B, 14B are configured to cooperate with each other (e.g., connect) to connect a plurality of rotor segments 14 around the radially outer periphery 12A of the rotor support hub 12. The first connector 12B may be adapted to be at least partially received within a cooperating second connector 14B, or vice versa, the second connector 14B may be adapted to be at least partially received within a cooperating first connector 12B. The cooperation of the first and second connectors 12B, 14B is facilitated by one or more first protrusions 30 that are received at least partially by one or more first recesses 32. Similarly, the cooperation of the first and second connectors 12B, 14B is facilitated by one or more protrusions 34 that are received at least partially by one or more recesses 36. As a result of this at least partial receipt of the one or more protrusions 30, 34 into the respective recesses 32, 36, when the first and second connectors 12B, 14B move relative to each other in any direction within a plane orthogonal to the major axis X-X, abutment between the first connector 12B and its cooperating second connector 14B will occur. Accordingly, the first connector 12B is retained within the second connector 14B, or vice versa, the second connector 14B is retained within the first connector 12B. The cooperation of the first and second connectors 12B, 14B restricts the movement of the rotor segment 14 relative to the rotor support hub 12 within a plane orthogonal to the major axis X-X. The cooperation of the first and second connectors 12B, 14B provides a snug connection between the rotor support hub 12 and the rotor segment 14, i.e., provides an approximate fit and / or play between each of the rotor support hub 12 and the rotor segment 14 within a plane orthogonal to the major axis X-X. As a result of the cooperation of the first and second connectors 12B, 14B, when these connectors 12B, 14B move relative to each other in any direction within a plane orthogonal to the major axis X-X, abutment of the first and second connection surfaces will occur.

[0026] The first and second connecting portions 12B, 14B may be configured to cooperate with each other to provide a clearance fit / slip fit with respect to each other. In other words, the first and second connecting portions 12B, 14B may be configured to cooperate with each other to allow movement of each of the rotor segments 124 relative to the rotor support hub 12 in a direction parallel to the major axis X-X. In fact, this allows each of the rotor elements 14 to be easily assembled to the rotor support hub 12. Accordingly, one of the plurality of gaps will be provided between the rotor support hub 12 and each of the plurality of rotor segments 14. Importantly, according to an embodiment of the present invention, the rotor support hub 12 and the rotor segments do not need to be tightly fitted only by the connecting portions 12B, 14B that connect them. Accordingly, the rotor support hub 12 and / or the rotor segments 14 do not need to be manufactured using a high-precision machining process.

[0027] The rotor assembly 10 further includes a plurality of fixing portions 26. In the present embodiment, the fixing portion 26 is a metal roll pin (which may also be called a spring pin or a tension pin). However, the fixing portion 26 is not limited to a roll pin and / or does not need to be metal. In some embodiments, one or more of the fixing portions 26 may be a pin, rod, bar, cylinder, or prism. Further, one or more of the fixing portions 26 may have magnetism or may not have magnetism. In some embodiments, one or more of the fixing portions 26 may be a polymer material, for example, a phenolic resin. The fixing portion 26 may be made of a fiber-reinforced material. The fixing portion 26 is received within each of the gaps between the rotor support hub 12 and each of the plurality of rotor segments and is configured to form an interference fit therebetween. Accordingly, the fixing portion 26 will function between the rotor support hub 12 and each of the rotor segments 14. The fixing portion 26 fixes each of the rotor segments 14 to the rotor support hub 12. To provide an interference fit, each of the fixing portions may have a width / diameter that is larger than the gaps between the rotor support hub 12 and each of the plurality of rotor segments 14.

[0028] To provide an interference fit, the fixing part 26 is forcibly inserted between the first and second connecting parts 12B, 14B. Each of the fixing parts 26 may have a length substantially equal to the stacking length of the rotor support hub 12. Each of the fixing parts 26 may have a constant cross-section substantially along its length. The forced insertion compresses each of the fixing parts 26, so that a compressive force is applied by the fixing parts 26 to each of the first and second connecting parts 12B, 14B. By this force, until the abutment of the first and second connecting parts 12B, 14B occurs as described above, the first and second connecting parts 12B, 14B move relative to each other in a plane perpendicular to the long axis X-X. The fixing part 26 biases the first and second connecting parts 12B, 14B relative to each other so as to provide a tight fit between the first and second connecting parts 12B, 14B. Therefore, the fixing part 26 biases the first and second connecting surfaces relative to each other.

[0029] In the illustrated embodiment, each of the first connecting parts 12B includes each of a plurality of recesses 28. Each of these recesses 28 is shaped to at least partially receive at least one of the fixing parts 26. The recesses 28 may be intended to deliberately provide each of the gaps at a desired position relative to either or both of the first and second connecting parts 12B, 14B. The recesses 28 may at least partially provide a gap between the first and second connecting parts 12B, 14B. The fixing part may be inserted anywhere between the first and second connecting parts 12B, 14B, but the recesses 28 facilitate insertion into an optimal position relative to the first connecting part 12B, the second connecting part 14B, or both of them.

[0030] FIG. 5 is a schematic view of a vehicle 100 including an electromechanical machine 102. The electromechanical machine 102 includes a rotor assembly 10. The electromechanical machine 102 generates a traction force for propelling the vehicle 100. The vehicle may be, for example, a hybrid electric vehicle (HEV), an electric vehicle (EV), or a plug-in hybrid electric vehicle (PHEV), and the vehicle 100 may be an automobile, an aircraft, or a ship. The problems associated with the use of a conventional two-piece rotor are the additional costs due to additional rotor components and the measures required for connecting the rotor poles and the central support. In at least some embodiments, the use of the fixing portion 28 reduces the need for expensive high-precision machining of the rotor support hub 12 and / or the rotor segment 14. In some embodiments, the thin plate 24 reduces the need for expensive machining of the rotor support hub 12.

[0031] The present invention is not limited to any of the details of the foregoing embodiments. For example, the rotor assembly 10 may include a rotor support hub 12 that is not composed of a plurality of first thin plates 24. The plurality of rotor segments 14 may be composed of a plurality of second thin plates or may not be composed of a plurality of second thin plates. In some embodiments, neither the first connection portion 12B nor the second connection portion 14B may include one of the plurality of recesses 28. Some embodiments may include a rotor hub 12 that does not have the first connection portion 12B. Any features disclosed herein (including any appended claims and drawings) may be combined in any manner, except combinations in which at least some of such features are mutually exclusive.

[0032] (Including any appended claims and drawings) Each feature disclosed herein may be replaced by an alternative feature that serves the same, equivalent, or similar purpose, unless expressly stated otherwise. Accordingly, unless expressly stated otherwise, each feature disclosed is merely an example of a general series of equivalent or similar features.

[0033] The present invention extends to any novel or novel combination of features disclosed herein (including any appended claims and drawings). The claims should not be construed as merely encompassing the foregoing embodiments, but rather should be construed as encompassing any embodiments that fall within the scope of the claims.

Claims

1. A rotor support hub having a plurality of first connection portions arranged around the rotor support hub, the rotor support hub, and A plurality of rotor segments each having a second connection portion, each of the second connection portions being configured to cooperate with at least one of the plurality of first connection portions to connect each of the rotor segments around the periphery of the rotor support hub. A plurality of rotor segments that are A plurality of fixing portions, each of the fixing portions being configured to be received between the first and second connection portions that cooperate with each other to fix the rotor segment to the rotor support hub and to cause an interference fit therebetween. A plurality of fixing portions that are Comprising The rotor support hub is composed of a plurality of thin plates and is formed of nitrogen-hardened stainless steel. Each of the plurality of first connection portions has a contour of a chestnut tree and protrudes radially outward. An electromechanical rotor assembly.

2. The rotor assembly according to claim 1, wherein at least one of the first connection portions or at least one of the second connection portions includes a recess configured to receive at least one of the plurality of fixing portions.

3. The rotor assembly according to claim 1 or 2, wherein at least one of the fixing portions is a pin.

4. The rotor assembly according to claim 1, 2, or 3, wherein at least one of the fixing portions is non-magnetic.

5. The rotor assembly according to any one of claims 1 to 4, wherein at least one of the fixing portions is made of or includes a polymer material.

6. The rotor assembly according to any one of claims 1 to 4, wherein at least one of the fixing portions is made of or includes a fiber-reinforced material.

7. The rotor assembly according to any one of claims 1 to 6, wherein one or more of the plurality of thin plates are joined to at least one other of the plurality of thin plates.

8. The rotor assembly according to any one of claims 1 to 7, wherein one or more of the plurality of thin plates are mechanically fixed to at least one other of the plurality of thin plates.

9. The rotor assembly according to any one of claims 1 to 8, further comprising a plurality of permanent magnets.

10. A rotor support hub for supporting a plurality of rotor segments, A plurality of thin plates, A plurality of first connection portions arranged around the rotor support hub for connection to the plurality of rotor segments; comprising; the rotor support hub is formed of nitrogen-hardened stainless steel; each of the plurality of first connection portions has the contour of a ginkgo leaf and projects radially outward; rotor support hub.

11. The rotor support hub according to claim 10, wherein the thin plate is substantially orthogonal to an axis that becomes the rotation axis of the rotor support hub during use.

12. The rotor support hub according to claim 10 or 11, wherein the thin plate is a single-piece thin plate.

13. The rotor support hub according to claim 12, wherein the thin plate is made from a sheet material.

14. The rotor support hub according to any one of claims 10 to 13, wherein the thin plate is made using a punch or a mold or by laser cutting.

15. An electromechanical rotor assembly comprising the rotor support hub according to any one of claims 10 to 14.

16. The rotor assembly according to claim 15, further comprising a plurality of rotor segments arranged around the rotor support hub.

17. An electromechanical machine comprising the rotor assembly according to any one of claims 1 to 9 or the rotor support hub according to any one of claims 10 to 14.

18. A vehicle comprising the electromechanical machine according to claim 17.

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