A cooling fluid end cap for a rotor of an electric machine

Abstract

An electric machine includes a plurality of laminations. The laminations include slots. Magnets are housed in the slots and the slots are arranged to form magnetic poles. The rotor includes a cooling fluid end cap for a rotor of the electric machine. The cooling fluid end cap includes an inlet. A first portion of the end cap is in fluid connection with the inlet. The first portion is a leading portion of the end cap when the rotor is rotating. The first portion has a first flow cross-sectional area. A second portion of the end cap is in fluid connection with the first portion and extends from the first portion. The second portion has a second flow cross-sectional area that is smaller than the first cross-sectional area.

Description

Background Technology

[0001] Electric motors are typically cooled using fluids directed to various parts of the motor. Especially with the increasing demand for electricity over time, improving cooling has been a key focus. Therefore, innovations to improve the cooling of internal motor components are highly welcome in this field. Summary of the Invention

[0002] Embodiments of this disclosure provide a rotor for an electric motor, including a plurality of laminations. Each lamination includes slots. Magnets are housed in the slots, and the slots are arranged to form magnetic poles. The rotor includes a cooling fluid end cap for the motor rotor. The cooling fluid end cap includes an inlet. A first portion of the end cap is in fluid communication with the inlet. When the rotor rotates, the first portion is the leading edge portion of the end cap. The first portion has a first flow cross-sectional area. A second portion of the end cap is in fluid communication with the first portion and extends from the first portion. The second portion has a second flow cross-sectional area smaller than the first cross-sectional area.

[0003] Embodiments of this disclosure also provide a rotor comprising a stack of laminations, wherein the laminations rotate relative to each other to create a skew angle in a common magnet slot. This slot thereby defines a fluid path adjacent to the magnet stack disposed within the slot. This path facilitates direct heat transfer from the magnets to the fluid as the fluid flows therein. Attached Figure Description

[0004] The following description should not be construed as limiting in any way. Referring to the accompanying drawings, the same parts are designated with the same reference numerals: Figure 1 This is a three-dimensional view of the rotor, showing the cooling oil flow channels arranged in the laminations; Figure 2 A perspective view shows a flow channel defining a fluid domain according to the invention, the fluid domain being used for cooling oil passing through a magnet slot; Figure 3 yes Figure 2 A diagram with magnets has been added for easier understanding; Figure 4 It is along Figure 2 The section line AA in Figure 2 A cross-sectional end view of the fluid domain; Figure 5 It shows Figure 2 A top view of the fluid domain; Figure 6 It shows Figure 2 The fluid domain along Figure 5 A sectional view of section line BB in the diagram; Figure 7 It shows Figure 2 The fluid domain along Figure 5 A sectional view of section line CC in the diagram; and Figure 8 An end view of a rotor is shown, which includes a plurality of radially adjacent end caps defining a fluid domain. Detailed Implementation

[0005] Referring to the accompanying drawings, one or more embodiments of the disclosed apparatus and methods are described in detail by way of example and not limitation.

[0006] Reference Figure 1 A perspective view of a prior art rotor 10 is shown to help the observer understand the disclosed innovation. It should be understood that the rotor shown includes prior art flow openings for illustration, but also serves as an illustration relevant to this disclosure because the overall appearance is very similar. Furthermore, it is not excluded that the innovation of this invention may be combined with prior art flow openings to produce a stronger cooling effect. This invention includes a different fluid path for cooling than known in the prior art, but rotors using this innovative path can still include existing openings and the aforementioned intended combinations. In the prior art, to reduce the overall weight and inertia of rotor 10, some rotors include openings 12. In some cases, cooling oil flows through openings 12 to further cool rotor 10.

[0007] According to the disclosure of the present invention, cooling oil can be flowed through path 14 (see [reference needed]) in the magnet slot (with an appropriate angle of inclination on the slot). Figure 2 and Figure 3 This is used to replace or enhance cooling. "Skew angle" is a technical term referring to the angle of rotational offset of one magnet relative to the next magnet within a series of magnets in a single magnet slot generated within a rotor lamination. Furthermore, according to one embodiment, end cap 16 is configured to improve fluid distribution through end cap 16 to path 14. Path 14 directs cooling oil to a second end cap 18 opposite end cap 16. End cap 18 includes an outlet 40 through which cooling oil exits the fluid domain. Therefore, it should be understood that the flow path within the magnet slot adjacent to the magnet disclosed herein, the end cap disclosed herein, or both are novel concepts.

[0008] Reference Figure 2 The image shows a negative three-dimensional image of the overall flow path 20 of a fluid domain segment 401 of rotor 10 according to the teachings of this document, which includes a path 14 for cooling fluid through rotor 10. Figure 3 yes Figure 2 The diagram has been enhanced with magnets for easier understanding. Figures 4-6 A specific size of an exemplary fluid domain is shown, based on an example. Figure 4 It shows Figure 2 The structure along Figure 2The section end view of section line AA in the figure. Figure 5 It shows Figure 2 A partial side view of the structure. Figure 6 It shows Figure 2 The structure along Figure 5 The sectional view of section line BB in the diagram.

[0009] The overall flow path 20 can also be referred to as the fluid domain, and it begins at inlet 21. Figures 4-6 In the example, the inlet 21 is arc-shaped, with an inner edge 23 defined by a radius of 14.5 mm and an outer edge 25 defined by a radius of 16.5 mm, such that the radial width is 2 mm.

[0010] In the exemplary rotor 10, multiple instances of flow paths 20 are arranged radially adjacent to each other within the rotor 10. Figure 8 An example is shown comprising four radially adjacent flow paths 20. Figure 8 In the example, the flow paths 20 are arranged in alternating directions such that each first end cap 16 is adjacent to two second end caps 18, and each second end cap 18 is adjacent to two first end caps 16. This configuration results in the cooling fluid flowing through the rotor 10 in alternating axial directions and improves the distribution of cooling. Similarly, this configuration can be used for any even number of radially adjacent flow paths 20, and is not limited to the four shown. Typically, each pole of the rotor has one flow path. For example, a rotor with eight poles has eight flow paths, with four flow paths flowing in one axial direction alternating with four flow paths flowing in the opposite axial direction.

[0011] As can be seen from the image, path 14 is a stepped, rotated, and angled arrangement, because it is defined by the rotated and angled magnet 22 and the stacked plate 24 as described above. Figure 5 As shown, each step 402, 404, 406, 408, defined by magnet 22 and lamination 24, extends 12.5 mm axially. The skewness of a particular rotor is related to the number of slots the stator has. Typically, the total skew angle from one axial end of the rotor to the opposite axial end causes a magnet at one axial end to be offset by one stator tooth pitch relative to a magnet at the opposite axial end. Rotor skewness counteracts cogging torque and / or noise vibration and acoustic roughness (NVH). For the specific example above, the skew angle of a 54-slot rotor could be 6.66°; for a 72-slot rotor, 5°; and for a 96-slot rotor, 3.75°. In the case of a 10-magnet rotor, the skew angle of a single magnet could be approximately 1 / 10 of the total skew angle, thus 0.666°, 0.5°, and 0.375°, respectively. Figure 4 , Figure 5 and Figure 6As shown, in one example, the skew angle 602 of a single magnet is 0.75°. Rotors typically have only 4-5 rotor skew steps. However, the rotor of this invention may require more (e.g., 10) skew steps because a rotor with 4 or 5 skew steps will not have a large skew angle between adjacent axial magnets. A smaller skew angle between adjacent axial magnets will not allow the paths 14 of adjacent magnets to overlap, hindering oil flow through the skewed paths 14.

[0012] Reference Figures 1-6 , Figure 7 It shows Figure 5 A side view along section line CC. This section intersects with the first part 30 and the second part 28. (As shown) Figure 7 As shown, the axial length of the first part 30 is 5 mm, and the axial length of the second part 28 is 1.5 mm. Compared with the first part 30, the second part 28 extends further in the circumferential direction.

[0013] Furthermore, the stepped section 406 defined by the magnet on the radially inner side of this structure is not supplied with cooling oil because a large amount of hot fluid travels from the stator to the magnet through the air gap. Additionally, the circular portion 407 is located near the center of the second portion 28, but is separated from the second portion 28 by a gap 405 to ensure that oil does not enter the circular portion 407. The circular portion 407 is fluidly connected to the supply branch 36.

[0014] from Figure 2 As can be seen, the slant angle ensures a continuous flow path in path 14 for delivering cooling oil. Cooling oil flowing through path 14, which is adjacent to the magnet, is preferable to cooling oil flowing through opening 12 (e.g., ...). Figure 1 (as shown), and therefore can replace the latter or be added to the latter for even larger overall cooling of rotor 10.

[0015] In addition to teaching the cooling oil to flow in path 14 adjacent to the magnet within magnet slot 16, it is recognized that the cooling fluid tends to move rapidly to the trailing portion of the cooling fluid end cap 16. More specifically, fluid in a rotating system similar to rotor 10 tends to be “left behind” as rotor 10 is driven to rotate. This means that fluid will tend to accumulate at the trailing portion 28 of end cap 16 (also referred to herein as the second portion). This causes the cooling fluid to be preferentially supplied to the lamination structure 24 via path 14b, while tending to move more quickly through the leading portion 30 of end cap 16 (also referred to herein as the first portion), thus failing to adequately supply path 14a.

[0016] To address this issue, the inventors configured the end cap 16 such that its flow cross-sectional area in the first portion 30 is larger than that in the second portion 28. In one example, the flow cross-sectional area of ​​the first portion 30 is defined by a rectangular cross-section having a first side of 3.5 mm and a second side of 5 mm, and the flow cross-sectional area of ​​the second portion 28 is defined by a rectangular cross-section having a first side of 6.3 mm and a second side of 1.5 mm. In one example, the radius of the radial inner edge of the second portion is 71 mm, and the radius of the radial outer edge of the second portion is 77.3 mm. The distance between the radial inner edge of the second portion 28 and the radial outer edge of the second portion 28 is sufficient to completely cover the opening of the step 402, thereby ensuring maximum cooling oil flow. The ratio of the cross-sectional area of ​​the first portion 30 to that of the second portion 28 is (3.5 × 5) / (6.3 × 1.5), or approximately 1.85.

[0017] The relatively small flow cross-sectional area in the second section 28 creates higher resistance to fluid entry, thus ensuring that fluid from the first section 30 is supplied to path 14a, rather than being diverted only to or almost exclusively to path 14b. In an alternative example, the ratio of cross-sectional areas can be in the range of 1.5-2.0, achieving a similar effect. Furthermore, in the case of using a second set of magnets 32 in a particular rotor, the second path 34 can also be supplied by an optional supply branch 36 from the first section 30. The optional supply branch 36 has a smaller cross-sectional area than either the first section 30 or the second section 28 because it supplies cooling oil to the smaller second path 34.

[0018] In the context of describing the invention (especially in the context of the appended claims), unless otherwise stated herein or clearly contradicted by the context, the use of the terms “a” and “an” and similar designations such as “the” should be interpreted to cover both singular and plural. Furthermore, it should be noted that the terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another. The terms “about,” “substantially,” and “generally” are intended to include the degree of error associated with a measurement of a specific quantity based on the equipment available at the time of filing. For example, “about” and / or “substantially” and / or “generally” can include a range of ±8% of a given value.

[0019] Although the invention has been described with reference to one or more exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from the basic scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed as the best mode for carrying out the invention, but rather the invention will include all embodiments falling within the scope of the claims. Moreover, exemplary embodiments of the invention have been disclosed in the drawings and description, and although specific terminology may have been used, it is used in a general and descriptive sense only, and not for limiting purposes, unless otherwise stated; therefore, the scope of the invention is not so limited.

Claims

1. A rotor for an electric motor: The rotor includes a plurality of laminations, each lamination including a slot and a magnet housed in the slot, the slots being arranged to form magnetic poles; The rotor includes a cooling fluid end cap for the rotor of an electric motor, the cooling fluid end cap comprising: import; The first part of the end cap is connected to the inlet fluid. When the rotor rotates, the first part is the leading edge part of the end cap, and the first part has a first flow cross-sectional area. The second portion of the end cap is fluidly connected to and extends from the first portion, and the second portion has a flow second cross-sectional area smaller than the first cross-sectional area.

2. The rotor according to claim 1, further comprising an outlet connected to the second portion.

3. The rotor according to claim 1, wherein the rotor comprises more than six magnets arranged axially within a magnetic pole, the magnets having a skew angle of less than 1° relative to each other.

4. The rotor according to claim 3, wherein the rotor comprises 10 magnets arranged axially.

5. The rotor according to claim 4, wherein the skew angle of each magnet is from about 0.5° to about 0.75°.

6. The rotor according to claim 1, wherein the ratio of the first cross-sectional area to the second cross-sectional area is in the range of about 1.5 to 2.

0.

7. The rotor according to claim 6, wherein the ratio of the first cross-sectional area to the second cross-sectional area is about 1.

85.

8. The rotor of claim 1, wherein the first portion and the second portion are respectively fluidly connected to a fluid flow channel of a magnet adjacent to the rotor.

9. The rotor of claim 1, wherein the first cross-sectional area is defined by a rectangular cross-section of 3.5 mm × 1.5 mm.

10. The rotor of claim 9, wherein the second cross-sectional area is defined by a rectangular cross-section of 6.3 mm × 1.5 mm.

11. The rotor of claim 1, wherein the second portion extends circumferentially compared to the first portion.

12. The rotor of claim 11, wherein the cross-sectional area of ​​the second portion is smaller than the cross-sectional area of ​​the first portion.

13. The rotor according to claim 1, further comprising a supply branch.

14. The rotor of claim 13, wherein the cross-sectional area of ​​the supply branch is smaller than the cross-sectional area of ​​the second portion.

15. The rotor according to claim 1, further comprising a circular portion in fluid communication with the supply branch.

16. The rotor of claim 15, wherein the circular portion is located near the center of the second portion and is not connected to the second portion.

17. A rotor comprising: A stack of laminations, wherein the laminations are rotated relative to each other to create a skewed pole angle in a common magnet slot, which thereby defines a fluid path adjacent to the stack of magnets disposed in the slot, the path facilitating direct heat conduction from the magnets to the fluid as the fluid flows therein.

18. The rotor of claim 17, further comprising a fluid end cap that fluidly connects a fluid source to the path.

19. The rotor of claim 18, wherein the end cap comprises: import; The first part of the end cap is connected to the inlet fluid. When the rotor rotates, the first part is the leading edge of the end cap, and the first part has a first flow cross-sectional area. The second portion of the end cap is fluidly connected to and extends from the first portion, and the second portion has a flow second cross-sectional area smaller than the first cross-sectional area.

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