Modular rotor design for electric motor

Abstract

The invention relates to a modular rotor design for an electric motor. A rotor of a motor and a method of assembly are provided. The rotor includes a hub. A plurality of micro-stacks are disposed along the length of the hub to form a stack having a stack length. Each micro-stack has the same length, and the stack length is less than the hub length of the hub. The rotor can be placed in the stator core to assemble the motor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of the prior filing date of U.S. Provisional Application Serial No. 63 / 589,899, filed on October 12, 2023, the entire disclosure of which is incorporated herein by reference. Background Art

[0003] Different vehicles typically have different operating requirements, such as regarding torque, performance, efficiency, etc. To achieve these different requirements, some motors may be designed with different lengths: shorter motors for vehicles with lower operating requirements, and longer motors for vehicles with higher operating requirements. Manufacturing motors with different lengths increases the cost of each motor due to the different design and manufacturing requirements. Summary of the invention

[0004] A method of assembling a motor is disclosed herein. A first micro-stack is assembled, the first micro-stack comprising a selected number of laminations. At least a second micro-stack is assembled, the at least second micro-stack comprising a selected number of laminations. The first micro-stack is assembled to a hub at a first longitudinal position at a first axial end of the hub, the hub extending from the first axial end to the second axial end over the length of the hub. At least a second micro-stack is assembled to the hub, wherein the first micro-stack and the at least second micro-stack form a stack having a stack length that is less than the length of the hub. A rotor is placed in a stator core to assemble the motor.

[0005] Also disclosed herein is a method for assembling a first rotor and a second rotor. A plurality of micro-stacks having the same length are assembled. A first subset of the micro-stacks is assembled onto a first hub of a first rotor having a first shaft length to form a first stack having a first stack length, the first hub having a first hub length. A second subset of the micro-stacks is assembled onto a second hub of a second rotor having a second shaft length to form a second stack having a second stack length, the second hub having a second hub length that is the same as the first hub length, wherein at least one of the following is satisfied: the first stack length is less than the first shaft length; and the second stack length is less than the second shaft length.

[0006] A rotor of a motor is also disclosed. The rotor includes: a hub; and a plurality of micro stacks arranged along the length of the hub to form a stack with a stack length, wherein each micro stack has the same length, and wherein the stack length is less than the hub length of the hub. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following description should not be considered limiting in any way. Referring to the accompanying drawings, similar elements are marked with similar numbers:

[0008] Figure 1 is a schematic diagram of a motor in an exemplary embodiment;

[0009] Figure 2 is a perspective view of a stator in an illustrative embodiment;

[0010] Figure 3 In the illustrative embodiment Figure 1 A perspective view of a hub of a rotor;

[0011] Figure 4 shows a perspective view of a micro-stack in an exemplary embodiment;

[0012] Figure 5 shows a perspective view of a micro-stack with magnets disposed in pockets;

[0013] Figure 6 A first rotor in an embodiment is shown;

[0014] Figure 7 A second rotor in an embodiment is shown;

[0015] Figure 8 The third rotor in the embodiment is shown;

[0016] Fig. 9 is a flow chart of a method of producing a series of rotors using the method disclosed herein;

[0017] Fig.10 shows a side cross-sectional view of a motor in an illustrative embodiment; and

[0018] Fig.11 A side cross-sectional view of another motor in an illustrative embodiment is shown. DETAILED DESCRIPTION

[0019] A detailed description of one or more embodiments of the disclosed apparatus and methods is presented herein by way of example and not limitation with reference to the accompanying figures.

[0020] Figure 1 is a schematic diagram of a motor 100 in an exemplary embodiment. The motor 100 extends from a first end 102 to a second end 104 along a longitudinal axis 105. The motor 100 includes a stator 106 and a rotor 108 that rotates within the stator 106. The stator 106 forms a hollow cylinder within which the rotor 108 rotates.

[0021] Figure 2 2 is a perspective view 200 of the stator 106 in an illustrative embodiment. The stator 106 includes a stator core 202 (or stator housing) extending along the longitudinal axis 105 and a set of wires 204 disposed along an inner wall of the stator 106.

[0022] Figure 3 In the illustrative embodiment Figure 1 300 is a perspective view of a hub 302 of a rotor 108. The hub 302 extends along the longitudinal axis 105 from a first axial end 304 to a second axial end 306. The hub 302 includes one or more slots 308 extending longitudinally. During manufacture of the rotor 108, the one or more slots 308 allow one or more micro stacks to slide on the hub 302. Figure 3 As shown, the micro stack 310 is located at one end of the hub 302. The micro stack 310 extends from a first micro stack end 312 to a second micro stack end 314. When placed on the hub 302, the first micro stack end 312 is located at the first shaft end 304, and the second micro stack end 314 is located at a selected distance from the first shaft end 304. Spacers (not shown) can be placed in the stator core (202, Figure 2 ) to extend across the remainder of the hub 302, thereby filling the gap extending from the second micro-stack end 314 to the second shaft end 306, thereby fixing the micro-stack 310 in the appropriate position on the hub 302.

[0023] Figure 4 A perspective view of a micro stack 310 in an exemplary embodiment is shown. The micro stack 310 is constructed by assembling a plurality of laminates side by side with each other. Each laminate is a thin disk with various cutouts in the disk. The laminates are bonded, interlocked or welded to each other to form a longitudinally extending micro stack. When the laminates are assembled to form the micro stack, the cutout areas are aligned to form a plurality of pockets and cooling channels in the micro stack 310.

[0024] The microstacks 310 form a ring extending along the longitudinal axis from a first microstack end 312 to a second microstack end 314. Each microstack 310 has an inner radial surface 402 and an outer radial surface 404. The inner radial surface 402 includes one or more keys 406 that are circumferentially aligned with one or more slots 308 of the hub 302.

[0025] The diameter of the central hole of the disk is approximately equal to the outer diameter of the hub 302. In one embodiment, the laminate has a thickness of about 0.025 mm. In other embodiments, the laminate can have a thickness of about 0.25 mm. For illustrative purposes, the micro-stack 310 shows a cavity 408 and a cooling channel 410 for a cooling fluid to flow through the micro-stack. In various embodiments, each micro-stack has 145 laminates bonded to each other, resulting in a micro-stack with a longitudinal length of 36.4 mm.

[0026] Figure 5A perspective view 500 of a micro-stack 310 is shown having a magnet 502 disposed in a pocket 408. The magnet 502 has a length that is generally equal to or slightly less than the axial length of the micro-stack 309. The magnet 502 can be bonded within the pocket 408 using a variety of adhesive materials and / or means, such as adhesives, epoxies, resins, plastics, or mechanical connections.

[0027] Figure 6 The first rotor 600 in the embodiment is shown. The first rotor 600 includes a plurality of micro stacks 602a-602f extending along the entire hub length of the hub 302. For illustrative purposes, six micro stacks are provided on the hub. The first micro stack 602a is assembled against the first shaft end 304 of the hub 302 and is placed at a first longitudinal position along the hub at the first shaft end. Then the second micro stack 602b is assembled against the first micro stack 602a and is placed at a second longitudinal position along the hub, and so on, until all micro stacks are attached to the hub 302, thereby forming a first stack 604 having a first stack length. Typically, a stack is a plurality of micro stacks placed axially against each other, and the stack length is the axial length of the stack. For the first stack 604, the first stack length is measured from the first end of the first micro stack 602a to the second end of the last micro stack (e.g., the sixth micro stack 620f). The length of each micro stack is about 36.4mm. Therefore, the first stack length of the first stack 604 is 218.4mm.

[0028] Figure 7 A second rotor 700 in an embodiment is shown. The second rotor 700 includes five micro stacks 602a-620e arranged along the hub 302. The first micro stack 602a is assembled against the first shaft end 304 of the hub 302. The second micro stack 602b is then assembled against the first micro stack 602a, and so on, until all five micro stacks are attached to the hub 302 to form the second stack 704. For the second rotor 700, the second stack length is measured from the first end of the first micro stack 602a to the second end of the fifth micro stack 620e. The second stack 704 has a stack length of 182 mm and is 36.4 mm shorter than the first stack length of the first stack 604. Spacers (not shown) can be placed in the stator core (202, Figure 2 ) to fill the axial gap 702 between the second end of the fifth micro stack 602e and the second axial end 306. The spacer can have the same axial length as the micro stack.

[0029] Figure 8 The third rotor 800 in the embodiment is shown. The third rotor 800 includes four micro stacks 602a-602d arranged along the hub 302. The micro stacks are similar to those in the present invention. Figure 6 and Figure 7 The third rotor 800 is assembled to the hub 302 in the same manner as disclosed, thereby forming a third stack 804. For the third rotor 800, the third stack length is measured from the first end of the first micro stack 602a to the second end of the fourth micro stack 620d. Stack 804 has a third stack length of 145.6 mm. A spacer having an axial length of two micro stacks can be placed on the stator core (202, Figure 2 ) to fill the axial gap 802 between the second end of the fourth micro stack 602d and the second axial end 306. Alternatively, two spacers, each having the axial length of one micro stack, can be placed to fill the space between the second end of the fourth micro stack 602d and the second axial end 306.

[0030] Any of the first rotor 600, the second rotor 700, and the third rotor 800 can be configured to have a non-zero skew angle in the rotor to reduce the torque ripple of the motor. To produce a non-zero skew angle, the micro-stacks are assembled at slightly different rotation angles from each other. This causes the magnets of the rotors to be skewed relative to each other. In one embodiment, the slots of the hub are longitudinally straight, and each micro-stack can have their keys at different angles along the inner wall of the disk to produce the skew angle.

[0031] Thus, each micro-stack can be assembled to the hub at varying rotational angles to create a skew effect. For the first rotor 600, the skew is a 6-step skew. For the second rotor, the skew is a 5-step skew. For the third rotor, the skew is a 4-step skew. In other embodiments, the rotors can be assembled with no skew to the micro-stacks. In this embodiment, all micro-stacks for all three rotor assemblies can be assembled to their respective hubs at the same rotational angle.

[0032] Typically, the micro-stacks are divided into at least a first subset of micro-stacks and a second subset of micro-stacks. The first subset of micro-stacks is used to manufacture a first rotor having a first stack length, and the second subset of micro-stacks is used to manufacture a second rotor having a second stack length. The number of micro-stacks in the first subset can be different from the number of micro-stacks in the second subset.

[0033] Fig. 9900 is a flow chart of a method for producing a series of rotors using the methods disclosed herein. In frame 902, laminates are obtained for constructing a desired number of micro-stacks. In one embodiment, the desired number is 15 micro-stacks. In frame 904, the laminates are bonded or welded to form a desired number of micro-stacks, wherein each micro-stack has the same length. Each micro-stack has at least one recess for accommodating a magnet. In frame 906, a magnet is inserted into the recess of each micro-stack. The length of the magnet is approximately equal to the length of one micro-stack. In frame 908, each magnet is fixed to each recess by an adhesive, epoxy, resin, plastic or mechanical connection. Rotors with different axial lengths are formed in frames 910, 912 and 914.

[0034] In block 910, n micro-stacks are sequentially assembled onto a first hub to form a first rotor 600 including a first stack 604 having a first stack length. In block 912, m micro-stacks are sequentially assembled onto a second hub to assemble a second rotor 700 including a second stack having a second stack length. In block 914, p micro-stacks are sequentially assembled onto a third hub to assemble a third rotor 800 including a third stack having a third stack length.

[0035] In one embodiment, n=6, m=5 and p=4, and thus, the first rotor has a first stack comprising 6 micro-stacks, the second rotor has a second stack comprising 5 micro-stacks, and the third rotor has a third stack comprising 4 micro-stacks. However, n, m and p can be any numbers different from each other so that the resulting stack made of n, m and p micro-stacks, respectively, does not exceed the hub length of the shaft hub. In addition, the method disclosed herein contemplates manufacturing only a first rotor having m micro-stacks and a second rotor having n micro-stacks, where m≠n.

[0036] The first rotor can be placed in the first stator core to form a first motor. The second rotor can be placed in the second stator core to form a second motor. The third rotor can be placed in the third stator core to form a third motor. The first stator core, the second stator core, and the third stator core can have the same axial length or stator length.

[0037] The components and assembly process are the same for all three hubs. In various embodiments, the micro-stacks can be heat-fitted to the hubs, thereby reducing cupping of the micro-stacks. In addition, cupping can be reduced or eliminated by full-face bonding the laminates of the micro-stacks to each other. For micro-stacks that are not cupped, the micro-stacks can be assembled on the hub 302 without bonding between each micro-stack. For further rigidity, each micro-stack can be bonded (e.g., point-bonded or full-face bonded) to each other micro-stack.

[0038] Although the micro-stack presented herein has a length of 36.4 mm, this is provided for illustrative purposes only. The micro-stack can have any desired length.

[0039] Fig.10 A side cross-sectional view of a motor 1000 in an illustrative embodiment is shown. The motor 1000 includes a stator core 1002 and a rotor 1004. The rotor 1004 includes a rotor hub 1006 and a plurality of micro stacks 1008a-1008e disposed along the rotor hub 1006. The plurality of micro stacks 1008a-1008e leave a gap 1010 at the end of the rotor hub 1006. A spacer 1012 is disposed in the gap 1010 and is a component of the stator core 1002. The effective stator 1014 is a section of the stator core 1002 that is equal to the length (extent, range) of the stack (e.g., the plurality of micro stacks 1008a-1008e). The length of the stator core 1002 minus the length of the spacer 1012 defines the effective length (effective stator length) of the effective stator 1014. For the motor 1000, the spacer 1012 is the length of one micro stack. For other motors having different numbers of micro-stacks, the spacer 1012 can be of an appropriate length (ie, the length of a number of micro-stacks) thereby changing the effective stator.

[0040] Fig.11 A side cross-sectional view of another motor 1100 in an illustrative embodiment is shown. A plurality of micro-stacks 1008a-1008f extend to the end of the rotor hub 1006. Therefore, no spacers are included in the motor 1100. Fig.11 The effective stator length is the same as the stator core length. Fig.10 and Fig.11 The length of the stator core is the same, but Fig.10 The effective stator length is less than Fig.11 The effective stator length.

[0041] Unless otherwise specified herein or clearly contradictory to the context, the use of the terms "a", "an" and "the" and similar indicators in the context of describing the present invention (particularly in the context of the following claims) should be interpreted as covering both the singular and the plural. In addition, it should be noted that the terms "first", "second", etc. herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms "approximately", "substantially" and "typically" are intended to include the degree of error associated with the measurement of a specific amount of equipment available at the time of filing an application. For example, "approximately" and / or "substantially" and / or "typically" can include a range of ±8% of a given value.

[0042] Although the present invention has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope of the present invention. In addition, many modifications may be made to adapt specific circumstances or materials to the teachings of the present invention without departing from the essential scope of the present invention. Therefore, it is intended that the present invention is not limited to the specific embodiments disclosed as the best mode for carrying out the present invention, but that the present invention will include all embodiments falling within the scope of the claims. In addition, in the drawings and descriptions, exemplary embodiments of the present invention have been disclosed, and although specific terms may have been employed, unless otherwise indicated, they are used only in a general and descriptive sense, and not for the purpose of limitation, and therefore the scope of the present invention is not limited thereto.

Claims

1. A method for assembling a motor, comprising: assembling a first micro-stack, the first micro-stack comprising a selected number of laminates; assembling at least a second micro-stack, at least the second micro-stack comprising a selected number of laminates; assembling the first micro-stack onto the hub at a first longitudinal position at a first axial end of the hub, the hub extending over a length of the hub from the first axial end to a second axial end; assembling at least the second micro-stack onto the hub, wherein the first micro-stack and at least the second micro-stack form a stack having a stack length that is less than a length of the hub; as well as The rotor is placed in the stator core to assemble the motor.

2. The method of claim 1 further comprising one of: (i) assembling four micro-stacks onto the hub; (ii) assembling five micro-stacks onto the hub; and (iii) assembling six micro-stacks onto the hub. 3 . The method of claim 1 , further comprising disposing a spacer on the stator core to fill an axial gap between the second micro-stack and the second axial end of the hub. 4 . The method of claim 1 , further comprising assembling the first micro-stack and the second micro-stack onto the hub to have a non-zero skew angle between the first micro-stack and the second micro-stack. 5 . The method of claim 1 , further comprising placing a first magnet into a first recess of the first micro-stack and placing a second magnet into a second recess of the second micro-stack.

6. The method according to claim 3, wherein: The stator core defines an effective stator having an effective stator length that is the length of the stator core minus the length of the spacers, wherein the effective stator length is the same as the stack length.

7. The method according to claim 1, wherein: The first micro-stack and the second micro-stack include the same number of laminates.

8. A method for assembling a first rotor and a second rotor, comprising: assembling multiple micro-stacks having the same length; assembling a first subset of mini-stacks onto a first hub of the first rotor to form a first stack having a first stack length, the first hub having a first hub length; as well as A second subset of mini-stacks is assembled onto a second hub of the second rotor to form a second stack having a second stack length, the second hub having a second hub length that is the same as the first hub length, wherein the first stack length is less than the second stack length.

9. The method according to claim 8, wherein: At least one of the first subset and the second subset includes one of: (i) four micro-stacks; (ii) five micro-stacks; and (iii) six micro-stacks.

10. The method according to claim 8, wherein: The first stack length of the first stack is less than a first hub length of the first hub, and the method further includes filling an axial gap between the first stack and an end of the first hub with a spacer.

11. The method of claim 8, further comprising at least one of: (i) assembling the first subset to the first rotor stack with a non-zero skew angle therebetween; and (ii) assembling the first subset to the first rotor stack without a skew angle.

12. The method according to claim 8, wherein: Each micro-stack of the plurality of micro-stacks includes a magnet disposed within a recess of the micro-stack.

13. The method of claim 8, further comprising placing the first rotor within a first stator core and placing the second rotor within a second stator core, wherein: A first effective length of a first effective stator of the first stator core is the same as the first stack length, and a second effective length of a second effective stator of the second stator core is the same as the second stack length.

14. The method according to claim 8, wherein: Each micro-stack includes the same number of laminates.

15. A rotor of a motor, comprising: Hub; as well as A plurality of micro-stacks are arranged along the length of the hub to form a stack having a stack length, wherein each micro-stack has the same length, and wherein the stack length is less than a hub length of the hub.

16. The rotor according to claim 15, wherein: The plurality of micro-stacks includes one of: (i) four micro-stacks; (ii) five micro-stacks; and (iii) six micro-stacks.

17. The rotor according to claim 15, wherein: The hub is disposed in a stator core and further includes a spacer disposed on the stator core to fill an axial gap between the stack and an end of the hub.

18. The rotor according to claim 15, wherein: The plurality of micro-stacks includes one of: (i) a first micro-stack and a second micro-stack having a non-zero skew angle therebetween; and (ii) a first micro-stack and a second micro-stack without a skew angle.

19. The rotor according to claim 15, wherein: Each of the plurality of micro-stacks includes a recess in which a magnet is disposed.

20. The rotor according to claim 15, wherein: Each micro-stack includes the same number of laminates.

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