Rotor

Abstract

Provided is a rotor that makes it possible for a magnet to be sufficiently fixed while suppressing magnetic resistance. The present invention comprises: a rotor core 3 that has a magnet accommodation hole 13; a magnet 5 that is provided in the magnet accommodation hole 13; and an elastic body 7 that is provided in the magnet accommodation hole 13 in a gap in the magnetization direction between the rotor core 3 and the magnet 5 and holds the magnet 5 in the magnet accommodation hole 13. The elastic body 7 comprises a magnetic body that is separate from the rotor core 3 and the magnet 5.

Description

rotor

[0001] The present invention relates to an IPM (Interior Permanent Magnet) rotor in which magnets are housed in magnet housing holes in a rotor core.

[0002] Conventional rotors include those in which magnets are fixed in magnet accommodating holes of the rotor using resin, as in Patent Document 1. However, resin creates magnetic resistance in the magnetic circuit, which reduces the amount of magnetic flux.

[0003] On the other hand, as in Patent Document 2, for example, some core pieces that make up the rotor are provided with spring plate portions that protrude into the magnet accommodating holes. The spring plate portions are bent by the magnets inserted into the magnet accommodating holes. The bent spring plate portions press the magnets against the inner periphery of the magnet accommodating holes to secure them in place.

[0004] However, the core pieces are made of magnetic steel plates, which are not suitable for springs. As a result, the spring plates integrated with the core pieces are prone to sagging, which reduces the load that secures the magnets. Therefore, with conventional technology, the magnets cannot be securely fixed, which can cause vibrations and other problems that can lead to rotor malfunctions.

[0005] Patent No. 7289785 Patent No. 7317856

[0006] The problem to be solved was that it was not possible to sufficiently fix the magnet while suppressing magnetic resistance.

[0007] The present invention provides a rotor comprising a rotor core having a magnet accommodating hole, a magnet arranged in the magnet accommodating hole, and an elastic body arranged in the gap in the magnetization direction between the rotor core and the magnet within the magnet accommodating hole and holding the magnet within the magnet accommodating hole, wherein the elastic body is made of a magnetic body separate from the rotor core and the magnet.

[0008] The present invention can sufficiently fix the magnet while suppressing magnetic resistance.

[0009] FIG. 1 is a perspective view of a rotor according to a first embodiment of the present invention. FIG. 2 is a plan view of the rotor of FIG. 1. FIG. 3 is an enlarged plan view showing a portion of the rotor of FIG. 2. FIG. 4 is a cross-sectional view taken along line VI-VI of FIG. 3. FIGS. 5(A) and 5(B) are enlarged plan views showing portions of rotors according to modified examples. FIG. 6 is a perspective view showing an elastic body of the rotor of FIG. 1.

[0010] The goal of sufficiently fixing the magnet while suppressing magnetic resistance was achieved by placing a separate elastic body made of magnetic material in the gap between the rotor core and the magnet inside the magnet accommodating hole.

[0011] The rotor 1 includes a rotor core 3, magnets 5, and an elastic body 7. The rotor core 3 includes magnet accommodating holes 13, and the magnets 5 are disposed within the magnet accommodating holes 13. The elastic body 7 is disposed in a gap S in the magnetization direction between the rotor core 3 and the magnets 5 within the magnet accommodating holes 13, and holds the magnets 5 within the magnet accommodating holes 13. The elastic body 7 is made of a magnetic material separate from the rotor core 3 and the magnets 5.

[0012] Various types of elastic body 7 can be used, but it may be, for example, an assembly of one or more wires. In this case, elastic body 7 may be a mesh spring or an assembly of metal fibers. The surface of the wire may be insulated.

[0013] The elastic body 7 may have a value obtained by multiplying the relative permeability and the space factor (%) of 1000 or more. The space factor is the percentage of the gap S between the rotor core 3 and the magnet 5 where the elastic body 7 is arranged that is occupied by the elastic body 7.

[0014] The elastic body 7 can be located on either side or both sides of the magnetization direction of the magnet 5. When the magnetization direction is the radial direction of the rotor core 3, the elastic body 7 is preferably located at least radially outward from the magnet 5.

[0015] [Structure of the rotor] Fig. 1 is a perspective view of a rotor according to a first embodiment of the present invention. Fig. 2 is a plan view of the rotor of Fig. 1. Fig. 3 is an enlarged view showing a part of the rotor of Fig. 2. Fig. 4 is a cross-sectional view taken along line VI-VI of Fig. 3.

[0016] 1 to 4 constitute a rotating electric machine together with a stator. The rotor 1 includes a rotor core 3, magnets 5, and an elastic body 7. The rotor 1 is an interior permanent magnet (IPM) rotor in which the magnets 5 are housed in magnet housing holes 13 of the rotor core 3.

[0017] The rotor core 3 is formed by stacking core pieces 9, each made of a plurality of annular plate materials, in the axial direction. The plurality of core pieces 9 of the rotor core 3 are integrated by welding, crimping, adhesive bonding, etc. Each core piece 9 is formed by punching out an electromagnetic steel plate or a silicon steel plate, for example. The axial direction means the direction along the axis of the rotor 1.

[0018] The rotor core 3 has a cylindrical shape as a whole. An axial hole 11 is provided in the center of the rotor core 3, and magnet accommodating holes 13 are provided around the axial hole 11. The axial hole 11 and the magnet accommodating holes 13 pass through the rotor core 3 in the axial direction and open at both end faces 3a of the rotor core 3 in the axial direction. Note that the magnet accommodating holes 13 may open only at one end face 3a of the rotor core 3.

[0019] The magnet accommodating holes 13 are arranged at four equal intervals in the circumferential direction of the rotor core 3. The circumferential direction refers to the direction along the outer periphery of the rotor core 3. Each magnet accommodating hole 13 is rectangular in plan view, and the dimension perpendicular to the radial direction is larger than the dimension in the radial direction. The radial direction refers to the direction along the diameter of the rotor core 3. Note that various changes can be made to the shape, number, arrangement, etc. of the magnet accommodating holes 13.

[0020] A magnet 5 is accommodated in each magnet accommodating hole 13. The magnet 5 can be composed of a permanent magnet (including pre-magnetized magnets), such as a sintered ferrite magnet piece or a neodymium magnet piece. The magnet 5 is a plate-shaped body that fits the magnet accommodating hole 13, and the dimensions of each part of the magnet 5 are set smaller than the dimensions of each part of the magnet accommodating hole 13. This creates a gap S between the rotor core 3 and the magnet 5 within the magnet accommodating hole 13.

[0021] An elastic body 7 is disposed in the radial gap S. Since the gap S is a space in which the elastic body 7 is disposed, it is shown in the drawing by a virtual line extending from the elastic body 7. The gap S does not need to be defined by the magnet 5 and the rotor core 3, and other members may be interposed between the elastic body 7 and the magnet 5 or the rotor core 3.

[0022] In this embodiment, the elastic body 7 is located radially outward from the magnet 5. However, the elastic body 7 can also be located radially inward from the magnet 5 as shown in Figure 5 (Figure 5(A)), or on both sides of the magnet 5 (Figure 5(B)).

[0023] In this embodiment, the radial direction is the magnetization direction, which is the direction in which the magnetic flux of the magnet 5 flows. Therefore, the elastic body 7 is disposed in the gap S in the magnetization direction between the rotor core 3 and the magnet 5 in the magnet accommodating hole 13. The magnetization direction is the direction of the magnetic flux at least from the magnet 5 to the rotor core 3, and can be made different from the radial direction depending on the specifications of the rotor 1, etc. For example, the magnetization direction can be the circumferential direction. In this case, the gap S between the rotor core 3 and the magnet 5 in the magnet accommodating hole 13 becomes a circumferential gap, and the elastic body 7 is disposed in this gap S.

[0024] FIG. 6 is a perspective view showing the elastic body 7. As shown in FIG.

[0025] As shown in Figures 1 to 6, the elastic body 7 holds the magnet 5 in the magnet accommodating hole 13. This elastic body 7 is made of a magnetic material separate from the rotor core 3 and the magnet 5. The elastic body 7 is plate-shaped overall, and is formed with a dimension in the magnetization direction larger than the gap S. This elastic body 7 is placed in the gap S in a radially compressed state, and presses and fixes the magnet 5 against the rotor core 3. Note that the elastic body 7 does not need to be plate-shaped as long as it can be placed in the gap S in a radially compressed state.

[0026] The material of the elastic body 7 is not particularly limited as long as it is a magnetic material, and various materials can be used. The elastic body 7 in this embodiment is an assembly of one or more wires, for example, an assembly of metal fibers such as steel wool, or a mesh spring.

[0027] Mesh springs are made by weaving spring wires and pressing them into shape. Metal fiber aggregates are made of metal fiber nonwoven fabrics, woven fabrics, sintered bodies, etc., formed into sheets. The wires used in mesh springs and the metal fibers that make up the aggregates may have their surfaces insulated with resin or the like.

[0028] It is preferable that the value obtained by multiplying the relative permeability and the space factor of such elastic body 7 is 1000 or more. For example, the relative permeability is 25 or more and the space factor is 40% or more. The space factor is the percentage of the gap S in which elastic body 7 is placed that is occupied by elastic body 7. If the value obtained by multiplying the relative permeability and the space factor is 1000 or more, the following magnetic resistance can be achieved when fixing magnet 5 with resin.

[0029] When placing the elastic body 7 in the gap S, a jig is used to compress the elastic body 7 in the radial direction and insert it into the gap S. Then, the jig is removed, leaving the elastic body 7 in the gap S, and the magnet is inserted at the same time. As another method, the elastic body 7 may be compressed in the radial direction using a jig while overlapping the magnet 5, and the elastic body 7 may be inserted into the gap S together with the magnet 5.

[0030] As another alternative, the elastic body 7 may be prepared so that it is longer than the gap S, and the elastic body 7 may be inserted into the magnet accommodating hole 13 first. In this case, the magnet 5 is inserted into the magnet accommodating hole 13 while compressing the elastic body 7 in the radial direction. At this time, pulling the elastic body 7 in the insertion direction of the magnet 5 allows for smooth insertion of the magnet 5. The portion of the elastic body 7 that protrudes from the magnet accommodating hole 13 can be cut off after the magnet 5 is fixed.

[0031] [Operation and Effect of the Rotor] In the rotor 1 of this embodiment, an elastic body 7 is disposed in the gap S in the magnetization direction between the rotor core 3 and the magnet 5 within the magnet accommodating hole 13. This elastic body 7 can press and hold the magnet 5 against the rotor core 3 in the magnetization direction within the magnet accommodating hole 13.

[0032] Because the elastic body 7 is separate from the rotor core 3 and magnets 5, it can be made of a material that does not easily wear out, enabling it to securely hold the magnets 5. Furthermore, because the elastic body 7 is made of a magnetic material, it can reduce the magnetic resistance within the gap S. In this embodiment, the value obtained by multiplying the relative permeability of the elastic body 7 by the space factor is 1000 or more, so it is possible to reliably reduce the magnetic resistance.

[0033] In this way, the rotor 1 of this embodiment can sufficiently fix the magnets 5 while suppressing magnetic resistance. Therefore, the rotor 1 can achieve improved performance, such as an increase in output torque.

[0034] Furthermore, even if there is variation in the size of the magnet accommodating hole 13 or the magnet 5, the elastic body 7 can fill the gap S, which changes in size accordingly, thereby reducing magnetic resistance and reliably holding the magnet 5. In other words, the elastic body 7 can increase the tolerance of the magnet 5 and the magnet accommodating hole 13.

[0035] Furthermore, if there is variation in the lamination of the core pieces 9 of the rotor core 3, unevenness will occur in the magnet accommodating holes 13 as shown in Figure 4. The elastic body 7 can absorb such unevenness within the magnet accommodating holes 13 and reliably hold the magnets 5. Moreover, by engaging the unevenness with the elastic body 7, the elastic body 7 can reliably hold the magnets in the magnet accommodating holes 13, resulting in an improved holding state of the magnets 5.

[0036] Furthermore, if the radial direction of the rotor core 3 is the magnetization direction and the elastic body 7 is positioned radially outward from the magnet 5, when the rotor 1 rotates in the rotating electric machine, the magnet 5 can be supported by the entire inner surface of the opposing magnet accommodating hole 13 via the elastic body 7.

[0037] Therefore, even if there is variation in the lamination of the core pieces 9 of the rotor core 3, the centrifugal force of the magnet 5 is prevented from acting on only a portion of the unevenness on the inner surface of the magnet accommodating hole 13, thereby preventing fatigue failure of the rotor 1.

[0038] REFERENCE SIGNS LIST 1 rotor 3 rotor core 3a end face 5 magnet 7 elastic body 13 magnet receiving hole S gap

Claims

1. A rotor comprising: a rotor core with a magnet accommodating hole; a magnet arranged in the magnet accommodating hole; and an elastic body arranged in the gap in the magnetization direction between the rotor core and the magnet within the magnet accommodating hole, the elastic body being made of a magnetic body separate from the rotor core and the magnet.

2. The rotor according to claim 1, wherein the elastic body is an assembly of one or more wires.

3. The rotor according to claim 2, wherein the elastic body is a mesh spring or an assembly of metal fibers.

4. A rotor according to any one of claims 1 to 3, wherein the relative permeability of the elastic body multiplied by its space factor is 1000 or more, and the space factor is the percentage of the gap between the rotor core in which the elastic body is disposed and the magnet that is occupied by the elastic body.

5. A rotor according to any one of claims 1 to 3, wherein the elastic body is located on one side or both sides of the magnetization direction of the magnet.

6. A rotor according to claim 5, wherein the magnetization direction is a radial direction of the rotor core, and the elastic body is positioned radially outward relative to the magnet.

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