Rotor, motor, and method for manufacturing rotor

Abstract

The disclosed rotor (30) is provided with: a cylindrical rotor core (31) in which a plurality of magnet holes (32) extending in the axial direction are formed; a plurality of permanent magnets (34) housed in the plurality of magnet holes (32); and an end plate (36) attached to one end of the rotor core (31) in the axial direction. The inner wall of the magnet hole (32) and the permanent magnet (34) are bonded to each other by a resin material (35). The end plate (36) is provided with a through hole (37) having an area equal to or less than half of the area of the magnet hole (32). At least a portion of the through hole (37) overlaps the magnet hole (32) when viewed from the axial direction.

Description

Technical Field

[0001] The present invention relates to a rotor, a motor and a method for manufacturing the rotor. Background Art

[0002] In the past, there is a known embedded magnet type rotor (for example, Patent Document 1). The rotor of Patent Document 1 includes a rotor core having a plurality of magnet holes and a plurality of permanent magnets housed in the plurality of magnet holes, and a resin layer is provided between the inner wall of the magnet hole and the permanent magnet. The resin layer is formed by heating the rotor core after inserting the permanent magnets coated with a thermosetting adhesive into the magnet holes.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-42771 Summary of the invention

[0006] However, when a permanent magnet coated with a thermosetting adhesive (or resin material) is inserted into a magnet hole, the resin material may be squeezed out and leaked from the magnet hole. In the case where the resin material leaks out from the magnet hole, it is necessary to remove the cured resin material by some means, which increases the man-hours for manufacturing the rotor. Under such circumstances, one of the purposes of the present invention is to suppress the leakage of the resin material from the magnet hole.

[0007] One aspect of the present invention relates to a rotor. The rotor includes: a cylindrical rotor core having a plurality of magnet holes extending in an axial direction; a plurality of permanent magnets housed in the plurality of magnet holes; and an end plate mounted on one end of the rotor core in the axial direction. The inner wall of the magnet hole and the permanent magnet are bonded to each other by a resin material. The end plate includes a through hole having an area less than half the area of ​​the magnet hole, and at least a portion of the through hole overlaps with the magnet hole when viewed from the axial direction.

[0008] Another aspect of the present invention relates to an electric motor. The electric motor includes: the above-mentioned rotor; and a stator facing the rotor with an air gap interposed therebetween.

[0009] Another aspect of the present invention relates to a method for manufacturing a rotor. The method includes: a first step of preparing a cylindrical rotor core having a plurality of magnet holes extending in the axial direction; a second step of attaching an end plate having a through hole having an area less than half of the area of ​​the magnet hole to one axial end of the rotor core in such a manner that at least a portion of the through hole overlaps with the magnet hole when viewed from the axial direction; a third step of preparing a plurality of permanent magnets; a fourth step of applying a resin material to at least one of the inner wall of the magnet hole and the permanent magnet; a fifth step of inserting the permanent magnet into the magnet hole from the other axial end side of the rotor core; and a sixth step of curing the resin material to fix the permanent magnet to the rotor core.

[0010] According to the present invention, it is possible to suppress leakage of the resin material from the magnet hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a front view schematically showing an example of the electric motor of the present invention.

[0012] Figure 2A It is a front view showing the rotor.

[0013] Figure 2B It is along Figure 2A A cross-sectional view of the rotor along line BB.

[0014] Figure 3 This is a front view showing an end plate included in the rotor.

[0015] Figure 4 This is a conceptual diagram for explaining the positions and shapes of the magnet hole, the permanent magnet, and the through hole, focusing on one magnetic pole. DETAILED DESCRIPTION

[0016] The embodiments of the rotor, the motor, and the method for manufacturing the rotor of the present invention are described below by giving examples. However, the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials are sometimes exemplified, but other numerical values ​​and materials may also be used as long as the effects of the present invention can be obtained.

[0017] (Rotor)

[0018] A rotor according to the present invention includes a cylindrical rotor core, a plurality of permanent magnets, and an end plate.

[0019] The rotor core is formed with a plurality of magnet holes extending in the axial direction thereof. One magnet hole may be provided for each magnetic pole, or a plurality of magnet holes may be provided for each magnetic pole. The shape of each magnet hole is not particularly limited, and for example, it may be considered to be rectangular, trapezoidal, crescent-shaped, arc-shaped, etc. when viewed from the axial direction. The rotor core may be formed by stacking a plurality of steel plates (for example, silicon steel plates), or may be formed by a pressed powder core. The rotor core may also have a center hole for the shaft to pass through.

[0020] A plurality of permanent magnets are housed in a plurality of magnet holes. The type of each permanent magnet is not particularly limited, and for example, it may be a rare earth magnet including a rare earth element such as neodymium. The shape of each permanent magnet may be, for example, a rectangular shape, an arc shape, etc. when viewed from the axial direction. Each permanent magnet may also be a sintered magnet. It should be noted that in this specification, a permanent magnet housed in one magnet hole is referred to as one permanent magnet. For example, even if two permanent magnets are housed in one magnet hole, the two permanent magnets are collectively regarded as one permanent magnet.

[0021] The inner wall of the magnet hole and the permanent magnet are bonded to each other by a resin material. The type of resin material is not particularly limited, but preferably a resin material including a thermosetting resin. The resin material may, for example, be sandwiched between a portion of the inner wall of the magnet hole located radially outward of the rotor core and a portion of the side of the permanent magnet facing radially outward of the rotor core. However, on this basis or in lieu thereof, the resin material may be present in other locations between the inner wall of the magnet hole and the permanent magnet. The thickness of the resin material may, for example, be greater than 0.16 mm and less than 0.30 mm.

[0022] The end plate is mounted on one axial end of the rotor core. The end plate may also be made of a steel plate (e.g., a silicon steel plate). The shape of the end plate may also be roughly circular. The end plate has a through hole having an area less than half the area of ​​the magnet hole. At least a portion of the through hole overlaps with the magnet hole when viewed from the axial direction of the rotor core. In other words, when viewed from the axial direction of the rotor core, at least a portion of the through hole overlaps with the magnet hole, and the area of ​​the through hole is less than half (less than 50%) of the area of ​​the magnet hole. The area of ​​the through hole may also be less than 40%, less than 30%, less than 20%, or less than 10% of the area of ​​the magnet hole.

[0023] By installing an end plate having such a through hole on one axial end of the rotor core, it is possible to suppress leakage of resin material when the permanent magnet is inserted into the magnet hole. Specifically, when the permanent magnet is inserted into the magnet hole, the insertion is performed after the resin material is applied to at least one of the two. When the permanent magnet is inserted deeper into the magnet hole, the through hole functions as an air discharge hole for releasing the air in the magnet hole to the outside. Therefore, even in the case where the rotor core is composed of laminated steel plates, it is possible to suppress leakage of resin material from between the laminated steel plates due to excessive increase in the internal pressure of the magnet hole. In addition, the area of ​​the through hole is small as described above, so it is difficult for the resin material applied to at least one of the inner wall of the magnet hole and the permanent magnet to leak to the outside through the through hole. Therefore, according to the end plate of the present invention, it is possible to suppress leakage of resin material from the magnet hole.

[0024] The end plate may also have two or more through holes relative to one magnet hole. For example, the end plate may have two through holes relative to one magnet hole, or may have three or more through holes relative to one magnet hole. According to this structure, the area required for each through hole to function as an air discharge hole can be reduced, so that the leakage of resin material from each through hole can be further suppressed.

[0025] Alternatively, when the rotor core is viewed from the axial direction, the through hole is included inside the outline of the permanent magnet. In other words, when viewed from the axial direction, the entire through hole overlaps with the permanent magnet. According to this structure, when viewed from the axial direction, the portion where the resin material is applied does not overlap with the through hole but is covered by the end plate, so that leakage of the resin material from the through hole can be further suppressed. It should be noted that, when viewed from the axial direction, a portion of the through hole does not overlap with the permanent magnet.

[0026] The through hole may also be a circular hole. A circular hole refers to a through hole whose shape when viewed from the axial direction is circular. It should be noted that the shape of the through hole when viewed from the axial direction is not limited thereto, and may be, for example, a square shape, a rectangular shape, an elliptical shape, a polygonal shape, etc.

[0027] The diameter of the circular hole may also be less than 2.8 mm. Alternatively or in lieu thereof, when the diameter of the rotor core is set to D, the diameter of the circular hole may be less than 0.045D. Alternatively, when the shape of the through hole as viewed from the axial direction is not circular, the area of ​​the shape may be set within the area range of the circular hole described above. With such a smaller through hole, it is possible to further suppress the leakage of the resin material from the magnet hole.

[0028] (Electric Motor)

[0029] The electric motor of the present invention comprises: the above-mentioned rotor; and a stator, which is opposite to the rotor with an air gap between them. The stator can be formed by stacking a plurality of steel plates (for example, silicon steel plates), or can also be formed by a pressed powder core. The stator can be an integral stator, or can also be a split stator. The stator can also comprise: a back yoke portion; a plurality of teeth portions, which protrude radially inward from the back yoke portion; and a coil, which is wound around each tooth portion. The coil can be wound in a distributed winding manner, or can be wound in a concentrated winding manner.

[0030] (Method of manufacturing rotor)

[0031] The manufacturing method of the rotor of the present invention can also be used to manufacture the above-mentioned rotor. The manufacturing method includes a first step, a second step, a third step, a fourth step, a fifth step and a sixth step. It should be noted that the execution order of each step is not limited by the order and name of the description.

[0032] In the first step, a cylindrical rotor core having a plurality of magnet holes extending in the axial direction is prepared.

[0033] In the second step, an end plate having a through hole having an area less than half that of the magnet hole is attached to one axial end of the rotor core so that at least a portion of the through hole overlaps with the magnet hole when viewed in the axial direction.

[0034] In the third step, a plurality of permanent magnets are prepared. The shape of each permanent magnet may be, for example, a rectangular shape when viewed from the axial direction.

[0035] In the fourth step, the resin material is applied to at least one of the inner wall of the magnet hole and the permanent magnet. That is, the resin material may be applied only to the inner wall of the magnet hole, only to the permanent magnet, or to both the inner wall of the magnet hole and the permanent magnet.

[0036] In the fifth step, the permanent magnet is inserted into the magnet hole from the other end side in the axial direction of the rotor core. At this time, leakage of the resin material from the magnet hole is suppressed in the same manner as described above.

[0037] In the sixth step, the resin material is cured to fix the permanent magnets to the rotor core. For example, when the resin material includes a thermosetting resin, the resin material can be cured by heating the rotor core.

[0038] As described above, according to the present invention, by providing the end plate having the small through-hole, it is possible to suppress the leakage of the resin material from the magnet hole.

[0039] Hereinafter, an example of the rotor, motor, and rotor manufacturing method of the present invention will be specifically described with reference to the accompanying drawings. The above-mentioned components and processes can be applied to the components and processes of the rotor, motor, and rotor manufacturing method of the example described below. The components and processes of the rotor, motor, and rotor manufacturing method of the example described below can be changed based on the above description. In addition, the matters described below can also be applied to the above-mentioned embodiment. The components and processes of the rotor, motor, and rotor manufacturing method of the example described below that are not necessary for the rotor, motor, and rotor manufacturing method of the present invention can also be omitted. It should be noted that the figures shown below are schematic figures and do not accurately reflect the shape and number of actual components.

[0040] (Electric Motor)

[0041] The motor 10 of this embodiment is an embedded magnet type motor. The motor 10 is configured as an inner rotor type three-phase synchronous motor, but is not limited thereto. Figure 1 As shown, the electric motor 10 includes a stator 20 and a rotor 30 .

[0042] The stator 20 is an integrated stator and includes: a substantially cylindrical back yoke portion 21; a plurality of (12 in this example) teeth 22 protruding radially inward from the back yoke portion 21; and a coil (not shown) wound in a distributed winding manner around each tooth 22. The stator 20 is formed by stacking a plurality of steel plates.

[0043] The rotor 30 is disposed inside the stator 20 and faces the stator 20 across an air gap. Figure 2A , Figure 2B as well as Figure 3 As shown, the rotor 30 includes: a cylindrical rotor core 31 ; a plurality of (ten in this example) permanent magnets 34 ; and an end plate 36 .

[0044] The rotor core 31 is formed with a plurality of magnet holes 32 extending in the axial direction (hereinafter referred to as the axial direction) of the rotor core 31. One magnet hole 32 is provided for each magnetic pole. The shape of each magnet hole 32 is substantially trapezoidal when viewed from the axial direction. The rotor core 31 is formed by stacking a plurality of steel plates. The rotor core 31 has a center hole 33 through which a shaft (not shown) is inserted.

[0045] The plurality of permanent magnets 34 are accommodated in the plurality of magnet holes 32. Each permanent magnet 34 is a sintered magnet, and has a rectangular shape when viewed from the axial direction.

[0046] The inner wall of the magnet hole 32 and the permanent magnet 34 are bonded to each other by a resin material 35. The resin material 35 includes a thermosetting resin. The resin material 35 is sandwiched between a portion of the inner wall of the magnet hole 32 located radially outward of the rotor core 31 and a portion of the side surface of the permanent magnet 34 facing radially outward of the rotor core 31.

[0047] The end plate 36 is mounted at one end in the axial direction. The end plate 36 is made of a steel plate of the same composition as the steel plate constituting the rotor core 31. The end plate 36 has a through hole 37 having an area less than half the area of ​​the magnet hole 32 at a position where the end plate 36 as a whole overlaps with the magnet hole 32 when viewed from the axial direction. The end plate 36 has a plurality of (two in this example) through holes 37 for each magnet hole 32. In particular, Figure 4 As shown, when viewed from the axial direction, the through hole 37 is included inside the outline of the permanent magnet 34. The through hole 37 is a circular hole, and its diameter is 2.8 mm or less. In addition, when the diameter of the core 31 is D, the diameter of the through hole 37 is 0.045D or less.

[0048] (Method of manufacturing rotor)

[0049] Next, a method for manufacturing the rotor 30 of the present embodiment will be described. The rotor manufacturing method includes a first step, a second step, a third step, a fourth step, a fifth step, and a sixth step.

[0050] In the first step, a cylindrical rotor core 31 having a plurality of magnet holes 32 extending in the axial direction is prepared.

[0051] In the second step, the end plate 36 having the through hole 37 having an area less than half that of the magnet hole 32 is attached to one axial end of the rotor core 31 so that the entire through hole 37 overlaps with the magnet hole 32 when viewed in the axial direction.

[0052] In the third step, a plurality of permanent magnets 34 are prepared.

[0053] In the fourth step, the resin material 35 composed of a thermosetting resin is applied to both the inner wall of the magnet hole 32 and the permanent magnet 34 .

[0054] In the fifth step, the permanent magnets 34 are inserted into the magnet holes 32 from the other axial end side of the rotor core 31 (that is, the side to which the end plate 36 is not attached).

[0055] In the sixth step, the rotor core 31 is heated to cure the resin material 35 , thereby fixing the permanent magnets 34 to the rotor core 31 .

[0056] Postscript

[0057] The following techniques are disclosed through the description of the above embodiments.

[0058] (Technique 1)

[0059] A rotor, wherein

[0060] The rotor has:

[0061] A cylindrical rotor core having a plurality of magnet holes extending in the axial direction;

[0062] a plurality of permanent magnets received in the plurality of magnet holes; and

[0063] an end plate mounted on one axial end of the rotor core,

[0064] The inner wall of the magnet hole and the permanent magnet are bonded to each other by a resin material.

[0065] The end plate has a through hole having an area less than half the area of ​​the magnet hole.

[0066] At least a portion of the through hole overlaps with the magnet hole when viewed from the axial direction.

[0067] (Technique 2)

[0068] The rotor according to technique 1, wherein:

[0069] The end plate includes a plurality of the through holes corresponding to the magnet holes.

[0070] (Technique 3)

[0071] A rotor according to technique 1 or 2, wherein:

[0072] The through hole is included inside the contour of the permanent magnet when viewed from the axial direction.

[0073] (Technique 4)

[0074] A rotor according to any one of techniques 1 to 3, wherein:

[0075] The through hole is a circular hole.

[0076] (Technique 5)

[0077] A rotor according to technique 4, wherein:

[0078] The through hole has a diameter of 2.8 mm or less.

[0079] (Technique 6)

[0080] A rotor according to technique 4 or 5, wherein:

[0081] When the diameter of the rotor core is defined as D, the diameter of the through hole is equal to or smaller than 0.045D.

[0082] (Technique 7)

[0083] A rotor according to any one of techniques 1 to 6, wherein:

[0084] The resin material includes a thermosetting resin.

[0085] (Technique 8)

[0086] A rotor according to any one of techniques 1 to 7, wherein:

[0087] The rotor core is formed by laminating a plurality of steel plates.

[0088] (Technique 9)

[0089] An electric motor, wherein

[0090] The electric motor has:

[0091] The rotor described in any one of techniques 1 to 8; and

[0092] The stator is opposed to the rotor with an air gap therebetween.

[0093] (Technology 10)

[0094] A method for manufacturing a rotor, wherein:

[0095] The manufacturing method of the rotor comprises:

[0096] In a first step, a cylindrical rotor core is prepared in which a plurality of magnet holes extending in the axial direction are formed;

[0097] A second step of attaching an end plate having a through hole having an area less than half of the area of ​​the magnet hole to one end of the rotor core in the axial direction in such a manner that at least a portion of the through hole overlaps with the magnet hole when viewed in the axial direction;

[0098] The third step is to prepare a plurality of permanent magnets;

[0099] A fourth step is to apply a resin material to at least one of the inner wall of the magnet hole and the permanent magnet;

[0100] A fifth step of inserting the permanent magnet into the magnet hole from the other end side in the axial direction of the rotor core; and

[0101] In a sixth step, the resin material is cured to fix the permanent magnet to the rotor core.

[0102] Industrial Applicability

[0103] The present invention can be used for a rotor, a motor, and a method for manufacturing the rotor.

[0104] Description of Reference Numerals

[0105] 10: Electric motor

[0106] 20: Stator

[0107] 21: Back yoke

[0108] 22: Tooth

[0109] 30: Rotor

[0110] 31: Rotor core

[0111] 32: Magnet hole

[0112] 33: Center hole

[0113] 34: Permanent magnet

[0114] 35: Resin material

[0115] 36: End plate

[0116] 37: Through hole.

Claims

1. A rotor, wherein: The rotor has: A cylindrical rotor core having a plurality of magnet holes extending in the axial direction; a plurality of permanent magnets received in the plurality of magnet holes; and an end plate mounted on one axial end of the rotor core, The inner wall of the magnet hole and the permanent magnet are bonded to each other by a resin material. The end plate has a through hole having an area less than half the area of ​​the magnet hole. At least a portion of the through hole overlaps with the magnet hole when viewed from the axial direction.

2. The rotor according to claim 1, wherein: The end plate includes two or more through holes for one magnet hole.

3. The rotor according to claim 1 or 2, wherein: The through hole is included inside the contour of the permanent magnet when viewed from the axial direction.

4. The rotor according to claim 1 or 2, wherein: The through hole is a circular hole.

5. The rotor according to claim 4, wherein: The diameter of the circular hole is less than 2.8 mm.

6. The rotor according to claim 4, wherein: When the diameter of the rotor core is set to D, the diameter of the circular hole is less than or equal to 0.045D.

7. The rotor according to claim 1 or 2, wherein: The resin material includes a thermosetting resin.

8. The rotor according to claim 1 or 2, wherein: The rotor core is formed by laminating a plurality of steel plates.

9. An electric motor, wherein: The electric motor has: The rotor according to claim 1 or 2; and The stator is opposed to the rotor with an air gap therebetween.

10. A method for manufacturing a rotor, wherein: The manufacturing method of the rotor comprises: In a first step, a cylindrical rotor core is prepared in which a plurality of magnet holes extending in the axial direction are formed; A second step of attaching an end plate having a through hole having an area less than half of the area of ​​the magnet hole to one end of the rotor core in the axial direction in such a manner that at least a portion of the through hole overlaps with the magnet hole when viewed in the axial direction; The third step is to prepare a plurality of permanent magnets; A fourth step is to apply a resin material to at least one of the inner wall of the magnet hole and the permanent magnet; A fifth step of inserting the permanent magnet into the magnet hole from the other end side in the axial direction of the rotor core; and In a sixth step, the resin material is cured to fix the permanent magnet to the rotor core.

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