Rotor of an electric motor

Abstract

This specification relates to a rotor in which magnets are fixed in magnet holes with foam adhesive, and provides a technology that prevents the foam adhesive from breaking and allows for efficient cooling of the magnets. [Solution] The rotor disclosed herein comprises a rotor core, a magnet hole, and a magnet. The magnet hole is provided in the rotor core and extends along the axis of the rotor core. The magnet is positioned in the magnet hole. The magnet hole has a contact surface that restricts the magnet from moving radially outward from the rotor, and has a space (inner space) in which the magnet can move radially inward. Furthermore, foam adhesive is filled in at least a portion of the gap between the magnet and the inner surface of the magnet hole between the contact surface and the inner space.

Description

Technical Field

[0001] The technology disclosed in this specification relates to the rotor of an electric motor.

Background Art

[0002] The rotor of an electric motor includes a rotor core and magnets. The rotor core is provided with magnet holes, and magnets are arranged in the magnet holes. The area of the magnet holes is larger than that of the magnets. The magnet holes have inner surfaces that restrict the movement of the magnets in several directions, and a part of the gap between the magnet holes and the magnets is filled with a foamed adhesive (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The movement of the magnets is not restricted in all directions within the magnet holes. There is a space in the magnet holes that allows the movement of the magnets, and that space is filled with a foamed adhesive. If the magnets can move in some directions within the magnet holes, there is a possibility that the magnets will move due to the centrifugal force acting on the magnets when the rotor rotates. When the foamed adhesive is stretched as the magnets move, there is a risk of the foamed adhesive breaking. On the other hand, if many sides of the magnets are in contact with the inner surfaces of the magnet holes, there is a risk that the magnets cannot be efficiently cooled. This specification provides a technology that can prevent the breaking of the foamed adhesive and efficiently cool the magnets.

Means for Solving the Problems

[0005] The rotor disclosed herein comprises a rotor core, a magnet hole, and magnets. The magnet hole is provided in the rotor core and extends along the axis of the rotor core. The magnets are positioned in the magnet hole. The magnet hole has a contact surface that restricts the magnets from moving radially outward from the rotor, and has a space (internal space) in which the magnets can move radially inward. Furthermore, at least a portion of the gap between the magnets and the inner surface of the magnet hole between the contact surface and the internal space is filled with foam adhesive.

[0006] In the rotor disclosed herein, even when centrifugal force is generated, the magnets do not move radially outward from the rotor core. Therefore, the foamed adhesive in the aforementioned area does not stretch significantly. In other words, rupture of the foamed adhesive is prevented. Furthermore, a space (internal space) is secured inside the magnets in the radial direction of the rotor core, and a coolant (which may be air) can pass through this space, allowing the magnets to be cooled efficiently.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] This is a view of the rotor of the embodiment from the axial direction. [Figure 2] This is a view of the rotor of the embodiment from the axial direction (the magnet and foam adhesive are drawn with dashed lines). [Modes for carrying out the invention]

[0009] The rotor 10 of the embodiment will be described with reference to the drawings. The rotor 10 is the rotor of an electric motor. Figure 1 is a view of the rotor 10 along the axis Ax. The main body of the rotor 10 is the rotor core 11, which is cylindrical in shape, but in Figure 1 only the sector-shaped portion with a central angle of 90 degrees is shown, and the remaining portion with a central angle of 270 degrees is omitted from the illustration. In the remaining 270-degree central angle range, there are three sector-shaped portions with the same structure as in Figure 1 arranged in a row.

[0010] The rotor core 11 is provided with multiple magnet holes 12, 22, magnets 13, 23, 33, and foam adhesives 14, 24, 34. The magnet holes 12, 22 extend along the axis Ax and penetrate the rotor core 11. In other words, the magnet holes 12, 22 extend parallel to the axis Ax.

[0011] Magnet 13 and foam adhesive 14 are placed inside magnet hole 12. Magnets 23 and 33 and foam adhesives 24 and 34 are placed inside magnet hole 22. Magnets 13, 23 and 33 are permanent magnets. The arrangement of magnet holes 12 and 22, magnets 13, 23 and 33, and foam adhesives 14, 24 and 34 is symmetrical with respect to the center line CL in Figure 1, so only the right side of the center line CL will be described below. Figure 2 shows only the right side of Figure 1. Also, in Figure 2, magnets 13, 23 and 33 and foam adhesives 14, 24 and 34 are shown by dashed lines to aid understanding.

[0012] The area of ​​the magnet hole 12, when viewed along the axis Ax, is larger than the area of ​​the magnet 13. The magnet 13, when viewed along the axis Ax, is rectangular. The magnet 13 also extends along the axis Ax, and its shape is a rectangular prism. The magnet 13 has four sides facing the inner surface of the magnet hole 12.

[0013] Of the four sides of the magnet 13, two adjacent sides on the radially outer side are in contact with the inner surface of the magnet hole 12. "Radially outer (inside)" means the side farther (closer) from the axis Ax of the magnet 13, and "two adjacent sides on the radially outer side of the magnet 13" means the two sides of the magnet 13 that are farther from the axis Ax. The inner surfaces of the magnet hole 12 that are in contact with the magnet 13 are called contact surfaces 15 and 16. One contact surface 15 is in contact with the entire side of one side of the magnet 13, while the other contact surface 16 is in contact with only a part of the other side of the magnet 13.

[0014] Since two adjacent radially outer surfaces of the magnet 13 are in contact with the contact surfaces 15 and 16 of the magnet hole 12, the magnet 13 does not move radially outward even when the rotor 10 rotates and centrifugal force acts on the magnet 13. The contact surfaces 15 and 16 restrict the radially outward movement of the magnet 13 inside the magnet hole 12.

[0015] On the other hand, within the space of the magnet hole 12, a space is secured radially inward from the magnet 13 in which the magnet 13 can move (hereinafter referred to as the inner space 12a). In other words, the entire surface of the side of the magnet 13 facing the inner space 12a is exposed. A coolant flows through this inner space 12a to cool the magnet 13. The coolant may be a fluid such as oil, or it may be air.

[0016] Another space (hereinafter referred to as the outer space 12b) is secured radially outside the magnet 13. In the outer space 12b, a portion of one side of the magnet 13 is exposed. Coolant can also flow into the outer space 12b.

[0017] On the opposite side of the contact surface 15, which is in contact with the entire surface of one side of the magnet 13, foam adhesive 14 is filled into the gap between the magnet 13 and the inner surface of the magnet hole 12. The foam adhesive 14 is elastic and compressible, and adheres tightly to the side of the magnet 13 and the inner surface of the magnet hole 12, fixing the magnet 13 in place. The magnet 13 is fixed inside the magnet hole 12 by the adhesive properties of the foam adhesive 14 and the pressure exerted by the foam adhesive 14. The magnet 13 is fixed while being pressed against the contact surfaces 15 and 16.

[0018] Although the foamed adhesive 14 is elastic, it may break if stretched too much. In the rotor 10 of the embodiment, the magnets 13 that are in contact with the contact surfaces 15 and 16 on the radially outer side of the rotor core 11 do not move radially outward even when centrifugal force is applied. Therefore, the foamed adhesive 14 does not stretch too much. In other words, the breakage of the foamed adhesive 14 is prevented. In addition, an inner space 12a and an outer space 12b are secured around the magnet 13, where the magnet 13 is exposed. Since a coolant can pass through these spaces, the magnet 13 can be cooled efficiently. In particular, since one side of the magnet 13 is entirely exposed to the inner space 12a, the magnet 13 can be cooled effectively.

[0019] The same applies to the magnets 23, 33 and the foam adhesives 24, 34 placed in the magnet hole 22. The magnet 23(33) is a rectangular prism, with four sides facing the inner surface of the magnet hole 22. Two adjacent radially outer sides of the magnet 23(33) are in contact with the inner surface of the magnet hole 22. "Two adjacent radially outer sides of the magnet 23(33)" refers to the two sides of the magnet 23(33) that are furthest from the axis Ax. The inner surfaces of the magnet hole 22 that are in contact with the magnet 23(33) are called contact surfaces 25, 26(35, 36). One contact surface 25(35) is in contact with the entire side of one of the magnets 23(33), while the other contact surface 26(36) is in contact with only a part of the other side of the magnet 23(33).

[0020] Since the magnet 23(33) is in contact with the contact surfaces 25, 26(35, 36), it does not move radially outward. The contact surfaces 25, 26(35, 36) restrict the radially outward movement of the magnet 23(33) inside the magnet hole 22.

[0021] On the opposite side of the contact surface 25(35) that is in contact with the entire surface of one side of the magnet 23(33), a foaming adhesive 24(34) is filled in the gap between the magnet 23(33) and the inner surface of the magnet hole 22. The foaming adhesive 24(34) has elasticity and is compressed, adheres to the side surface of the magnet 23(33) and the inner surface of the magnet hole 22, and fixes the magnet 23(33). The magnet 23(33) is fixed inside the magnet hole 22 by the adhesiveness of the foaming adhesive 24(34) and the pressure received from the foaming adhesive 24(34). The magnet 23(33) is fixed while being pressed against the contact surfaces 25, 26(35, 36).

[0022] In the space of the magnet hole 22, an inner space 22a(22c) in which the magnet 23(33) can move is secured radially inward of the magnet 23(33), and an outer space 22b(22d) is secured radially outward of the magnet 23(33). In other words, the entire side surface of the magnet 23(33) facing the inner space 22a(22c) is exposed, and a part of the other side surface is exposed to the outer space 22b(22d). Since a refrigerant can flow through these spaces 22a, 22b(22c, 22d), the magnet 23(33) can be efficiently cooled. In particular, since the entire side surface of one side of the magnet 23(33) is exposed to the inner space 22a(22c), the magnet 23(33) can be effectively cooled.

[0023] Points to note regarding the technology described in the embodiment are described. In FIG. 2, only a range of 45 degrees of the central angle of the cylindrical rotor 10 is shown, but the remaining part also has the same structure. The arrangement of the magnets is not limited to the arrangement of the embodiment. The arrangement of the magnets may be a "polygonal arrangement", a "V-shaped arrangement", a "double V-shaped arrangement", an "inverted triangular arrangement", or the like.

[0024] The foaming adhesive 14 is in a gel state before being filled in the magnet hole 12, but solidifies while having elasticity in the magnet hole 12. The foaming adhesive 14 may also be expressed as a foaming adhesive sheet. The same applies to the foaming adhesives 24 and 34.

[0025] The entire surface of one side of the magnet 13 is in contact with the contact surface 15. Foam adhesive 14 is filled between the inner surface of the magnet hole 12 that faces the contact surface 15 with the magnet 13 in between, and the magnet 13. The foam adhesive 14 only needs to fill at least a portion of the space between the surface that faces the contact surface 15 with the magnet 13 in between, and the magnet 13. The same applies to the foam adhesives 24 and 34.

[0026] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0027] 10: Rotor 11: Rotor core 12, 22: Magnet holes 12a, 22a, 22c: Inner space 12b, 22b, 22d: Outer space 13, 23, 33: Magnets 14, 24, 34: Foam adhesive 15, 16, 25, 26, 35, 36: Contact surface

Claims

[Claim 1] It is the rotor of an electric motor, Rotor core and A magnet hole is provided in the rotor core and extends along the axis of the rotor core, A magnet placed in the aforementioned magnet hole, It is equipped with, The magnet hole has a contact surface that restricts the magnet from moving radially outward from the rotor, and has a space that allows the magnet to move radially inward. A foam adhesive is filled in at least a portion of the gap between the contact surface and the space, between the magnet and the inner surface of the magnet hole. Rotor.

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