Rotor core

Abstract

To provide a rotor core capable of increasing strength around a center bridge while suppressing a short circuit of magnetic flux in the center bridge.SOLUTION: The rotor core includes magnet insertion holes arranged symmetrically with respect to the center bridge and adjacent to each other in the circumferential direction in each of a plurality of magnetic poles provided along the circumferential direction. Each of the magnet insertion holes includes a magnet insertion portion, an air hole that is provided on a side closer to the center bridge than the magnet insertion portion and is filled with resin, and an engagement portion that protrudes inward of the air hole and engages with the filled resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rotor core. [Background technology]

[0002] Conventionally, rotor cores have been disclosed in which permanent magnet insertion holes are provided circumferentially symmetrically on either side of a center bridge (see, for example, Patent Document 1). Patent Document 1 discloses a support structure in which a coupling element is coupled to an air groove formed in the permanent magnet insertion hole, thereby increasing the strength of the rotor core. Here, the air groove in which the coupling element is arranged is formed in an area of ​​the permanent magnet insertion hole away from the center bridge, separating the permanent magnets. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-516939 Summary of the Invention [Problem to be solved by the invention]

[0004] The center bridge of the rotor core can become a magnetic path through which short-circuit magnetic flux passes. Therefore, from the perspective of suppressing short-circuiting of magnetic flux, it is desirable to have a narrow center bridge. However, narrowing the center bridge reduces the strength against centrifugal force generated when the rotor core rotates at high speed. While Patent Document 1 can increase the strength of the rotor core, there is room for improvement when focusing on the strength around the center bridge.

[0005] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rotor core that can increase the strength around the center bridge while suppressing short circuits of magnetic flux in the center bridge. [Means for solving the problem]

[0006] The above objective is achieved by a rotor core having magnet insertion holes arranged symmetrically about a center bridge and adjacent to each other in the circumferential direction at each of a plurality of magnetic poles arranged along the circumferential direction, each of the magnet insertion holes having a magnet insertion portion, an air hole that is arranged closer to the center bridge than the magnet insertion portion and is filled with resin, and an engagement portion that protrudes inward from the air hole and engages with the filled resin. [Effects of the Invention]

[0007] A rotor core can be provided that can increase the strength around the center bridge while suppressing short circuits of magnetic flux in the center bridge. [Brief explanation of the drawings]

[0008] [Figure 1] Fig. 1A is an explanatory diagram of a rotor including a rotor core according to a first embodiment, and Fig. 1B is an enlarged view of first and second magnet insertion holes arranged circumferentially symmetrically with a center bridge therebetween. [Figure 2] FIG. 2 is an enlarged view of one magnetic pole formed on the rotor in the first embodiment. [Figure 3] FIG. 3 is an enlarged view of one magnetic pole formed on the rotor in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) The rotor 1 shown in FIG. 1 includes a rotor core 10 and a first permanent magnet 18 embedded in the rotor core 10. The rotor 1 forms a rotating electric machine together with a stator (not shown) consisting of three phases: U phase, V phase, and W phase. The rotating electric machine formed by the rotor 1 is a permanent magnet synchronous rotating electric machine, a so-called IPM (Interior Permanent Magnet) motor. A rotating shaft (not shown) is fixed to the center of the rotor 1. The rotor 1 of this embodiment forms an 8-pole, 24-slot motor.

[0010] The rotor 1 has an even number of magnetic poles 2 (eight in FIG. 1) arranged at equal intervals in the circumferential direction across the q axis. The polarities of the even number of magnetic poles 2 alternate in the circumferential direction. The rotor core 10 has a center bridge 12 for each magnetic pole 2. A d-axis that passes through the center of the center bridge 12 extends radially in each magnetic pole 2. Each magnetic pole 2 has a structure that is symmetrical in the circumferential direction across the d-axis. Therefore, the rotor core 10 has a first magnet insertion hole 11 and a second magnet insertion hole 15 that are symmetrically arranged with respect to the center bridge 12 and adjacent in the circumferential direction in each magnetic pole 2.

[0011] 1(B) and 2, the first magnet insertion hole 11 includes a magnet insertion portion 11a. A first permanent magnet 18 is inserted into the magnet insertion portion 11a. The first magnet insertion hole 11 includes a first air hole 11b on the side closer to the center bridge 12 than the magnet insertion portion 11a, i.e., closer to the d-axis. A first resin portion 19a1 filled with resin is formed in the first air hole 11b. The first magnet insertion hole 11 includes a second air hole 11c on the side farther from the center bridge 12 than the magnet insertion portion 11a, i.e., closer to the q-axis. A second resin portion 19a2 filled with resin is formed in the second air hole 11c. The resin forming the first resin portion 19a1 and the second resin portion 19a2 can be a conventionally known resin material, such as epoxy resin. Note that for ease of understanding, the resin-filled portions are hatched in each figure.

[0012] The rotor core 10 includes a first engaging portion 13 and a second engaging portion 14 that protrude inward from the first air hole 11b and engage with the first resin portion 19a1.

[0013] First engagement portion 13 includes large diameter portion 13a and small diameter portion 13b. First engagement portion 13 protrudes inward of first air hole 11b because small diameter portion 13b is connected to outer circumferential side wall portion 11b1 of first air hole 11b. First engagement portion 13 has a configuration in which small diameter portion 13b forms a constriction, allowing large diameter portion 13a to engage with first resin portion 19a1.

[0014] Second engagement portion 14 includes large diameter portion 14a and small diameter portion 14b. Second engagement portion 14 protrudes inward from first air hole 11b because small diameter portion 14b is connected to inner circumferential wall portion 11b2 of first air hole 11b. Second engagement portion 14 has a configuration in which small diameter portion 14b forms a constriction, allowing large diameter portion 14a to engage with first resin portion 19a1.

[0015] The first engagement portion 13 and the second engagement portion 14 are provided in the first air hole 11b. The first engagement portion 13 and the second engagement portion 14 are engaged with the first resin portion 19a1. Therefore, when the rotor 1 rotates, stress acting on the vicinity of the center bridge 12 due to centrifugal force can be alleviated.

[0016] The second magnet insertion hole 15 is formed symmetrically to the first magnet insertion hole 11 with respect to the center bridge 12. Therefore, the second magnet insertion hole 15 includes a magnet insertion portion 15a. A first permanent magnet 18 is inserted into the magnet insertion portion 15a. The second magnet insertion hole 15 includes a third air hole 15b on the side closer to the center bridge 12 than the magnet insertion portion 15a, i.e., on the side closer to the d-axis. A third resin portion 19b1 filled with resin is formed in the third air hole 15b. The second magnet insertion hole 15 includes a fourth air hole 15c on the side farther from the center bridge 12 than the magnet insertion portion 15a, i.e., on the side closer to the q-axis. A fourth resin portion 19b2 filled with resin is formed in the fourth air hole 15c. As with the first resin portion 19a1, the resin forming the third resin portion 19b1 and the fourth resin portion 19b2 can be a conventionally known resin material.

[0017] Rotor core 10 has third engagement portions 16 and fourth engagement portions 17 that protrude inward into third air holes 15b and engage with third resin portions 19b1. Third engagement portion 16 corresponds to first engagement portion 13 provided in first air hole 11b. Fourth engagement portion 17 corresponds to second engagement portion 14 provided in first air hole 11b. Therefore, a description of the configuration, action, and function of these portions will be omitted here.

[0018] By providing the first engagement portion 13, the second engagement portion 14, the third engagement portion 16, and the fourth engagement portion 17, it is possible to alleviate the stress acting on the vicinity of the center bridge 12 due to centrifugal force when the rotor 1 rotates. This allows the width, which is the circumferential dimension of the center bridge 12, to be narrowed. As a result, it is possible to suppress short-circuiting of magnetic flux. In other words, it is possible to increase the strength around the center bridge while suppressing short-circuiting of magnetic flux. By suppressing short-circuiting of magnetic flux, it is possible to efficiently utilize the magnetic flux. As a result, it is possible to drive the motor with high efficiency even if the amount of magnets is reduced, and it is possible to miniaturize the motor.

[0019] On the other hand, the installation of each engaging portion does not reduce the installation space for the magnets or impede magnet installation. This makes it easier to ensure the desired amount of magnets. Ensuring the desired amount of magnets improves motor performance.

[0020] The rotor core 10 has a first engagement portion 13 and a third engagement portion 16 provided on the radially outer side. The rotor core 10 has a second engagement portion 14 and a fourth engagement portion 17 provided on the radially inner side. The rotor core 10 may have either the first engagement portion 13 and the third engagement portion 16 provided on the radially outer side, or the second engagement portion 14 and the fourth engagement portion 17 provided on the radially inner side. Whether the engagement portion is provided on the radially outer side or the radially inner side can be selected as appropriate based on the size and arrangement of the permanent magnets, etc.

[0021] The engaging portions are preferably provided so as to relieve centrifugal force, that is, stress acting on a line extending radially outward from the center point of rotor core 10. For this reason, for example, it is more preferable that the engaging portions in first air hole 11b be connected to outer circumferential wall portion 11b1 or inner circumferential wall portion 11b2 rather than to bridge wall surface 12a (see FIG. 2) of center bridge 12. It is also preferable that the engaging portions provided in other air holes be similarly arranged.

[0022] Second Embodiment Next, a rotor 5 according to a second embodiment will be described with reference to FIG. 3. The rotor 5 includes a rotor core 30 and first and second permanent magnets 18 and 28 embedded in the rotor core 30. Similar to the rotor 1 according to the first embodiment, the rotor 5 includes an even number of magnetic poles 6 arranged at equal intervals in the circumferential direction across the q-axis. The rotor core 30 includes a center bridge 12 and a center bridge 22 for each magnetic pole 6. A d-axis passing through the center of the center bridges 12 and 22 extends radially in each magnetic pole 6. Each magnetic pole 6 has a circumferentially symmetrical structure across the d-axis. Therefore, the rotor core 30 includes a first magnet insertion hole 11 and a second magnet insertion hole 15 for each magnetic pole 6, which are symmetrically arranged with respect to the center bridge 12 and adjacent to each other in the circumferential direction. The rotor core 30 also includes a third magnet insertion hole 21 and a fourth magnet insertion hole 25, which are symmetrically arranged with respect to the center bridge 22 and adjacent to each other in the circumferential direction. A first permanent magnet 18 is inserted into the first magnet insertion hole 11 and the second magnet insertion hole 15. A second permanent magnet 28 is inserted into the third magnet insertion hole 21 and the fourth magnet insertion hole 25.

[0023] The second permanent magnet 28 is disposed radially outward of the first permanent magnet 18. The dimensions of the first permanent magnet 18 in the second embodiment are smaller than those in the first embodiment. Furthermore, the dimensions of the first magnet insertion hole 11 and the second magnet insertion hole 15 into which the first permanent magnet 18 is inserted in the second embodiment are smaller than those in the first embodiment. However, since these configurations are common to the first embodiment, the same reference numerals are used in the drawings and detailed description thereof will be omitted.

[0024] The third magnet insertion hole 21 has a magnet insertion portion 21a. A second permanent magnet 28 is inserted into the magnet insertion portion 21a. The third magnet insertion hole 21 has a fifth air hole 21b on the side closer to the center bridge 22 than the magnet insertion portion 21a, i.e., on the side closer to the d-axis. A fifth resin portion 29a1 filled with resin is formed in the fifth air hole 21b.

[0025] The rotor core 30 includes a fifth engaging portion 23 and a sixth engaging portion 24 that protrude inward into the fifth air hole 21b and engage with the fifth resin portion 29a1.

[0026] The fourth magnet insertion hole 25 has a magnet insertion portion 25a. A second permanent magnet 28 is inserted into the magnet insertion portion 25a. The fourth magnet insertion hole 25 has a sixth air hole 25b on the side closer to the center bridge 22 than the magnet insertion portion 25a, i.e., on the side closer to the d-axis. A sixth resin portion 29b1 filled with resin is formed in the sixth air hole 25b.

[0027] The rotor core 30 includes a seventh engaging portion 26 and an eighth engaging portion 27 that protrude inward into the sixth air hole 25b and engage with the sixth resin portion 29b1.

[0028] The fifth engagement portion 23 and the sixth engagement portion 24 correspond to the first engagement portion 13 and the second engagement portion 14. Therefore, a description of their configuration, action, and function will be omitted here. Furthermore, the seventh engagement portion 26 and the eighth engagement portion 27 correspond to the third engagement portion 16 and the fourth engagement portion 17. Therefore, a description of their configuration, action, and function will be omitted here.

[0029] In the second embodiment, too, it is possible to alleviate stress acting in the vicinity of the center bridges 12 and 22. This makes it possible to narrow the width, which is the circumferential dimension, of the center bridges 12 and 22. As a result, it is possible to suppress short-circuiting of magnetic flux.

[0030] [Effects] This embodiment is provided with an air hole filled with resin, located closer to the center bridge than the magnet insertion section, and an engaging section that protrudes inward from this air hole and engages with the resin. This makes it possible to increase the strength of the area around the center bridge while suppressing short circuits of magnetic flux in the center bridge.

[0031] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0032] 1,5...rotor, 2,6...magnetic pole, 10,30...rotor core, 11...first magnet insertion hole, 11a...magnet insertion portion, 11b...first air hole, 12,22...center bridge, 13...first engagement portion, 14...second engagement portion, 15...second magnet insertion hole, 15a...magnet insertion portion, 15b...third air hole, 16...third engagement portion, 17...fourth engagement portion, 18...first permanent magnet, 19a1...first resin portion, 21...third magnet insertion hole, 21a...magnet insertion portion, 21b...fifth air hole, 23...fifth engagement portion, 24...sixth engagement portion, 25...fourth magnet insertion hole, 25a...magnet insertion portion, 25b...sixth air hole, 26...seventh engagement portion, 27...eighth engagement portion, 28...second permanent magnet, 29a1...fifth resin portion, 29b1...sixth resin portion

Claims

[Claim 1] A rotor core having magnet insertion holes that are symmetrically arranged with respect to a center bridge and adjacent to each other in the circumferential direction, in each of a plurality of magnetic poles provided along the circumferential direction, Each of the magnet insertion holes has a magnet insertion portion, an air hole that is provided closer to the center bridge than the magnet insertion portion and is filled with resin, and an engagement portion that protrudes inward from the air hole and engages with the filled resin. Rotor core.

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