Rotor core

Abstract

This invention provides a rotor core capable of both suppressing short circuits in the magnetic flux at the central bridge and increasing the strength around the central bridge. The rotor core has multiple magnetic poles arranged circumferentially, each having magnet insertion holes symmetrically arranged relative to the central bridge and adjacent to it in the circumferential direction. Each magnet insertion hole has: a magnet insertion portion; an air hole located closer to the central bridge than the magnet insertion portion and filled with resin; and an engaging portion protruding inward from the air hole and engaging with the filled resin.

Description

Technical Field

[0001] This utility model relates to a rotor core. Background Technology

[0002] Conventionally, rotor cores with insertion holes for permanent magnets symmetrically arranged circumferentially across a center bridge have been disclosed (see, for example, Patent Document 1). Patent Document 1 discloses a support structure in which a connecting element engages with an air groove formed in the insertion hole of the permanent magnet. This improves the strength of the rotor core. Here, the air groove with the connecting element is formed in the insertion hole of the permanent magnet in a region away from the center bridge, across the permanent magnet.

[0003] Patent Document 1: Japanese Patent Publication No. 2021-516939

[0004] However, the central bridge of the rotor core may become a magnetic path through which short-circuit flux passes. Therefore, from the viewpoint of suppressing short circuits of magnetic flux, a narrower width of the central bridge is preferable. However, if the width of the central bridge is narrowed, the strength relative to the centrifugal force generated when the rotor core rotates at high speed is reduced. Patent Document 1 can improve the strength of the rotor core, but there is room for improvement when considering the strength around the central bridge. Utility Model Content

[0005] Therefore, the purpose of this invention is to provide a rotor core that can both suppress short circuits of magnetic flux at the center bridge and improve the strength around the center bridge.

[0006] The above objective is achieved by a rotor core having a plurality of magnetic poles arranged circumferentially with magnet insertion holes symmetrically arranged relative to the central bridge and adjacent to each other in the circumferential direction. Each magnet insertion hole has: a magnet insertion portion; an air hole located closer to the central bridge than the magnet insertion portion and filled with resin; and an engaging portion protruding inward from the air hole and engaging with the filled resin.

[0007] A rotor core capable of both suppressing short circuits in the magnetic flux at the center bridge and increasing the strength around the center bridge. Attached Figure Description

[0008] Figure 1 (A) is an explanatory diagram of a rotor having the rotor core of the first embodiment. Figure 1 (B) is an enlarged view of the first magnet insertion hole and the second magnet insertion hole, which are symmetrically arranged in the circumferential direction across the central bridge.

[0009] Figure 2 This is an enlarged view of one magnetic pole of the rotor formed in the first embodiment.

[0010] Figure 3This is an enlarged view of one magnetic pole of the rotor formed in the second embodiment. Detailed Implementation

[0011] (First Implementation)

[0012] Figure 1 The rotor 1 shown includes a rotor core 10 and a first permanent magnet 18 embedded in the rotor core 10. The rotor 1, together with a stator (not shown) consisting of three phases (U, V, and W), forms a rotary motor. The rotary motor formed by the rotor 1 is a permanent magnet synchronous type rotary motor, a so-called IPM (Interior Permanent Magnet) motor. A rotating shaft (not shown) is fixed at the center of the rotor 1. In this embodiment, the rotor 1 forms an 8-pole, 24-slot motor.

[0013] The rotor 1 has an even number of evenly spaced components arranged circumferentially at intervals along the q-axis. Figure 1 The rotor core 10 has eight magnetic poles 2. The polarities of the even-numbered magnetic poles 2 alternately reverse in the circumferential direction. Each magnetic pole 2 has a central bridge 12. In each magnetic pole 2, the d-axis extends radially through the center of the central bridge 12. Each magnetic pole 2 has a circumferentially symmetrical structure across the d-axis. Therefore, the rotor core 10 has a first magnet insertion hole 11 and a second magnet insertion hole 15 in each magnetic pole 2 that are symmetrically arranged with respect to the central bridge 12 and adjacent in the circumferential direction.

[0014] Reference Figure 1 (B) and Figure 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 has a first air hole 11b on the side closer to the central 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 has a second air hole 11c on the side farther from the central 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 used to form the first resin portion 19a1 and the second resin portion 19a2 can be, for example, a conventionally known resin material such as epoxy resin. Furthermore, to facilitate understanding, the resin-filled portions are shaded in the figures.

[0015] The rotor core 10 has a first engaging portion 13 and a second engaging portion 14 that protrude into the inside of the first air hole 11b and engage with the first resin portion 19a1.

[0016] The first engaging portion 13 includes a large-diameter portion 13a and a small-diameter portion 13b. The first engaging portion 13 is continuously provided with the small-diameter portion 13b and the outer peripheral sidewall portion 11b1 of the first air hole 11b, and thus protrudes inward toward the first air hole 11b. For the first engaging portion 13, a neck is formed by the small-diameter portion 13b, so that the large-diameter portion 13a can engage with the first resin portion 19a1.

[0017] The second engaging portion 14 includes a large-diameter portion 14a and a small-diameter portion 14b. The second engaging portion 14 is formed by the small-diameter portion 14b being continuously disposed with the inner peripheral sidewall portion 11b2 of the first air hole 11b, thus protruding inward towards the first air hole 11b. For the second engaging portion 14, a neck is formed by the small-diameter portion 14b, so that the large-diameter portion 14a can engage with the first resin portion 19a1.

[0018] The first engaging portion 13 and the second engaging portion 14 are provided in the first air hole 11b. Furthermore, the first engaging portion 13 and the second engaging portion 14 engage with the first resin portion 19a1. Therefore, when the rotor 1 rotates, the stress acting on the vicinity of the central bridge 12 due to centrifugal force can be mitigated.

[0019] The second magnet insertion hole 15 is formed symmetrically with respect to the central bridge 12 and the first magnet insertion hole 11. 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 has a third air hole 15b on the side closer to the central bridge 12 than the magnet insertion portion 15a, i.e., 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 has a fourth air hole 15c on the side away from the central bridge 12, i.e., closer to the q-axis, relative to the magnet insertion portion 15a. A fourth resin portion 19b2 filled with resin is formed in the fourth air hole 15c. The resin used to form the third resin portion 19b1 and the fourth resin portion 19b2 is the same as that used for the first resin portion 19a1, and conventionally known resin materials can be used.

[0020] The rotor core 10 has a third engaging portion 16 and a fourth engaging portion 17 that protrude into the third air hole 15b and engage with the third resin portion 19b1. The third engaging portion 16 corresponds to the first engaging portion 13 provided in the first air hole 11b. The fourth engaging portion 17 corresponds to the second engaging portion 14 provided in the first air hole 11b. Therefore, a description of these structures, functions, and effects is omitted here.

[0021] By incorporating the first engaging portion 13, the second engaging portion 14, the third engaging portion 16, and the fourth engaging portion 17, the stress acting near the center bridge 12 due to centrifugal force during rotor 1 rotation can be mitigated. Therefore, the circumferential dimension, i.e., the width, of the center bridge 12 can be narrowed. As a result, short circuits in the magnetic flux can be suppressed. That is, both short circuits in the magnetic flux and the strength around the center bridge can be improved. By suppressing short circuits in the magnetic flux, the magnetic flux can be utilized effectively. Therefore, even with a reduced amount of magnets, the motor can be driven efficiently, enabling motor miniaturization.

[0022] On the other hand, the arrangement of each engaging part does not reduce the space for magnet placement or obstruct magnet placement. Therefore, it is easy to ensure the desired amount of magnets. By ensuring the desired amount of magnets, motor performance can be improved.

[0023] The rotor core 10 includes a first engaging portion 13 and a third engaging portion 16 disposed on the radially outer side. The rotor core 10 also includes a second engaging portion 14 and a fourth engaging portion 17 disposed on the radially inner side. Alternatively, the rotor core 10 may include any one of the first engaging portion 13 and the third engaging portion 16 disposed on the radially outer side, and the second engaging portion 14 and the fourth engaging portion 17 disposed on the radially inner side. The choice of which side (radially outer or radially inner) to provide the engaging portions can be appropriately selected based on the size and arrangement of the permanent magnets.

[0024] Furthermore, the engaging portion is preferably configured to mitigate centrifugal force, i.e., stress acting on a radially outward line from the center point of the rotor core 10. Therefore, for example, the engaging portion in the first air hole 11b interacts with the bridge wall 12a of the central bridge 12 (see reference). Figure 2 Compared to continuous arrangement, it is preferable to continuously arrange the outer peripheral sidewall portion 11b1 and the inner peripheral sidewall portion 11b2. The same arrangement is also preferable for the engaging portions located at other air holes.

[0025] (Second Implementation)

[0026] Next, refer to Figure 3The rotor 5 of the second embodiment will be described. The rotor 5 includes a rotor core 30 and a first permanent magnet 18 and a second permanent magnet 28 embedded in the rotor core 30. Similar to the rotor 1 of the first embodiment, the rotor 5 has an even number of magnetic poles 6 arranged at equal intervals along the circumferential direction, separated by a q-axis. The rotor core 30 has a central bridge 12 and a central bridge 22 at each magnetic pole 6. At each magnetic pole 6, the d-axis extends radially through the center of the central bridges 12 and 22. Each magnetic pole 6 has a circumferentially symmetrical structure separated by the d-axis. Therefore, the rotor core 30 has a first magnet insertion hole 11 and a second magnet insertion hole 15 arranged symmetrically with respect to the central bridge 12 and adjacent in the circumferential direction at each magnetic pole 6. Additionally, it has a third magnet insertion hole 21 and a fourth magnet insertion hole 25 arranged symmetrically with respect to the central bridge 22 and adjacent in the circumferential direction. The first permanent magnet 18 is inserted into the first magnet insertion hole 11 and the second magnet insertion hole 15. The second permanent magnet 28 is inserted into the third magnet insertion hole 21 and the fourth magnet insertion hole 25.

[0027] The second permanent magnet 28 is disposed radially outside the first permanent magnet 18. The size of the first permanent magnet 18 in the second embodiment is smaller than that in the first embodiment. Furthermore, in the second embodiment, the sizes of the first magnet insertion hole 11 and the second magnet insertion hole 15 for inserting the first permanent magnet 18 are smaller than those in the first embodiment. However, these structures are common to the first embodiment, therefore, the same reference numerals are used in the drawings, and detailed descriptions are omitted.

[0028] 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 central bridge 22 than the magnet insertion portion 21a, that is, on the side closer to the d-axis. A fifth resin portion 29a1 filled with resin is formed in the fifth air hole 21b.

[0029] The rotor core 30 has a fifth engaging portion 23 and a sixth engaging portion 24 that protrude toward the inside of the fifth air hole 21b and engage with the fifth resin portion 29a1.

[0030] 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 central bridge 22 than the magnet insertion portion 25a, that is, on the side closer to the d-axis. A sixth resin portion 29b1 filled with resin is formed in the sixth air hole 25b.

[0031] The rotor core 30 has a seventh engaging portion 26 and an eighth engaging portion 27 that protrude into the inside of the sixth air hole 25b and engage with the sixth resin portion 29b1.

[0032] The fifth engaging part 23 and the sixth engaging part 24 correspond to the first engaging part 13 and the second engaging part 14. Therefore, a description of these structures, functions, and uses is omitted here. Similarly, the seventh engaging part 26 and the eighth engaging part 27 correspond to the third engaging part 16 and the fourth engaging part 17. Therefore, a description of these structures, functions, and uses is omitted here.

[0033] In this second embodiment, the stress acting near the central bridges 12 and 22 can also be mitigated. Therefore, the circumferential dimension, i.e., the width, of the central bridges 12 and 22 can be narrowed. As a result, short circuits in the magnetic flux can be suppressed.

[0034] [Effect]

[0035] This embodiment includes: an air hole located on the side of the magnet insertion portion near the central bridge and filled with resin; and an engaging portion protruding inward from the air hole and engaging with the resin. This allows for both suppression of short circuits in the magnetic flux at the central bridge and enhancement of the strength around the central bridge.

[0036] The embodiments of the present utility model have been described in detail above, but the present utility model is not limited to the specific embodiments described above. Various modifications and alterations can be made within the scope of the spirit of the present utility model as described in the scope of protection claimed in this application.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1, 5…Rotor; 2, 6…Magnetic poles; 10, 30…Rotor core; 11…First magnet insertion hole; 11a…Magnet insertion part; 11b…First air hole; 12, 22…Center bridge; 13…First engaging part; 14…Second engaging part; 15…Second magnet insertion hole; 15a…Magnet insertion part; 15b…Third air hole; 16…Third engaging part; 17…Fourth engaging part; 18…First permanent magnet; 19a1…First resin part; 21…Third magnet insertion hole; 21a…Magnet insertion part; 21b…Fifth air hole; 23…Fifth engaging part; 24…Sixth engaging part; 25…Fourth magnet insertion hole; 25a…Magnet insertion part; 25b…Sixth air hole; 26…Seventh engaging part; 27…Eighth engaging part; 28…Second permanent magnet; 29a1…Fifth resin part; 29b1…Sixth resin part.

Claims

1. A rotor core having magnet insertion holes symmetrically arranged with respect to a central bridge and adjacent to each other in the circumferential direction among a plurality of magnetic poles arranged along the circumferential direction, wherein, The magnet insertion holes each have: a magnet insertion portion; an air hole located on a side closer to the central bridge than the magnet insertion portion and filled with resin; and an engaging portion protruding into the air hole and engaging with the filled resin.

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