Rotor, rotary electric machine, and method of manufacturing rotor

Abstract

To enable reduction in coercive force of a permanent magnet without decrease in torque of a rotary electric machine.SOLUTION: According to an embodiment, a rotor 100 has a rotor shaft 110, a rotor core 120, and a permanent magnet 130. The rotor core 120 has two outer magnet accommodation holes 121, two first inner magnet accommodation holes 122 and second inner magnet accommodation holes 123, forming pairs with respect to the d-axis within each magnetic pole 101. The permanent magnet 130 has outer magnets 131, first inner magnets 132, and second inner magnets 133, arranged symmetrically with respect to the d-axis. A thickness of the second inner magnet 133 is larger than a thickness of the first inner magnet 132.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a rotor, a rotating electrical machine, and a method for manufacturing a rotor.

Background Art

[0002] In an embedded permanent magnet rotor, in each magnetic pole, there is an example in which they are arranged symmetrically with respect to the circumferential direction with respect to the d-axis at the center of the magnetic pole. In such a case, further, there is an example in which the magnets are arranged in a plurality of layers of two or more layers.

[0003] Regarding the permanent magnet rotor, improving torque, that is, improving performance, and further reducing the coercive force of the permanent magnet are effective for cost reduction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] As for the torque of the permanent magnet rotor, it is necessary to consider the magnet torque and the reluctance torque.

[0006] FIG. 6 is a partial cross-sectional view showing a conventional example of a rotating electrical machine, showing one magnetic pole portion sandwiched between two q-axes and its adjacent portion. The rotating electrical machine shown in FIG. 6 has a rotor 100 and a stator 10. The rotor 100 has a rotor shaft 110, a rotor core 120, and permanent magnets 130. Each magnetic pole of the rotor 100 illustrated in FIG. 6 is symmetric with respect to the d-axis at the center of the magnetic pole, and on each of the left and right sides of FIG. 6, it has an outer magnet 131, an inner first magnet 132, and an inner second magnet 133. Further, in the rotor core 120, an outer magnet housing hole 121, an inner first magnet housing hole 122, and an inner second magnet housing hole 123 connected to the inner first magnet housing hole 122 are formed to house the outer magnet 131, the inner first magnet 132, and the inner second magnet 133, respectively. Furthermore, between adjacent magnetic poles, a weight reduction hole 126 is formed radially inward across the q-axis.

[0007] Here, in the rotor core 120, the first portion of the magnetic path that generates reluctance torque is the magnetic path F between the outer magnet housing hole 121 and the inner first magnet housing hole 122 and the inner second magnet housing hole 123. P1 That is. Also, the second portion of the magnetic path that generates reluctance torque is the magnetic path F between two adjacent inner first magnet housing holes 122 across the q-axis. P2 That is. Furthermore, the third portion of the magnetic path that generates reluctance torque is the magnetic path F between the inner second magnet housing hole 123 and the weight reduction hole 126. P3 That is. The magnetic path F P2 is connected so as to branch into the magnetic paths F P3 on both sides of the q-axis. Therefore, the magnetic path F P2 and the two magnetic paths F P3 shall be collectively referred to as the q-axis magnetic path. In addition to these, the radially outer side of the outer magnet housing hole 121 also becomes a magnetic path that generates reluctance torque.

[0008] Here, for example, if an attempt is made to increase the magnetic torque by thickening the inner second magnet 133 on the radially inner side as shown by the broken line portion while maintaining the width of the magnetic path F P1 , the magnetic path F P3The width becomes narrow. As a result, the flow of the magnetic flux in the q-axis magnetic path is suppressed, the reluctance torque decreases, and there is a possibility that the effect of torque increase cannot be achieved.

[0009] Therefore, even if the thickness of the permanent magnet on the radially inner side is increased, the torque is not reduced, and furthermore, it is desirable to cause a reduction in the coercive force of the permanent magnet even in part.

[0010] An object of the present invention is to provide a rotor and a rotating electrical machine capable of reducing the coercive force of a permanent magnet without accompanying a decrease in torque.

Means for Solving the Problems

[0011] In order to achieve the above object, a rotor according to an embodiment of the present invention includes a rotor shaft extending in the rotational axis direction, and is attached to the rotor shaft. At each magnetic pole, two outer magnet housing holes are formed so as to be paired with respect to the d-axis of the magnetic pole center at the radially outer portion, and two inner first magnet housing holes are formed so as to be paired with respect to the d-axis at a position radially inner than the outer magnet housing holes. An inner second magnet housing hole is formed on the radially inner side of each of the two inner first magnet housing holes. The rotor includes an outer magnet housed in the outer magnet housing hole, an inner first magnet housed in each of the inner first magnet housing holes, and an inner second magnet housed in each of the inner second magnet housing holes. The thickness of the inner second magnet is larger than the thickness of the inner first magnet.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, a rotor, a rotating electrical machine, and a manufacturing method of the rotor according to embodiments of the present invention will be described. Here, the same or similar parts are denoted by common reference numerals, and redundant descriptions are omitted.

[0014] [First Embodiment] FIG. 1 is a longitudinal sectional view showing the rotating electrical machine 1 according to the first embodiment. Further, FIG. 2 is a partial cross-sectional view showing the rotating electrical machine 1 according to the first embodiment.

[0015] The rotating electrical machine 1 includes a rotor 100, a stator 10, a bearing 20 that rotatably supports the rotor 100, a bearing bracket 30 that statically supports the bearing 20, and a frame 40 that houses the stator 10 and supports the bearing bracket 30.

[0016] The rotor 100 has a rotor shaft 110 extending in the axial direction, a rotor core 120 attached to the radially outer side of the rotor shaft 110, and a permanent magnet 130 housed in the rotor core 120. The permanent magnet 130 has an outer magnet 131 shown in FIG. 1, an inner first magnet 132, and an inner second magnet 133 shown in FIG. 2.

[0017] The stator 10 has a stator core 11 and a stator winding 15. The stator core 11 has a plurality of stator slots 12 formed at intervals in the circumferential direction, and a plurality of stator teeth 13 formed by the adjacent stator slots 12. Further, the stator winding 15 is wound around the stator teeth 13.

[0018] The rotor 100 has a plurality of magnetic poles arranged sequentially in the circumferential direction. In FIG. 2, one magnetic pole 101 and a part of the magnetic poles on both sides adjacent thereto are shown.

[0019] Here, each magnetic pole 101 is a region sandwiched between two q - axes extending from the rotation axis CL. In FIG. 2, a case where the permanent magnets 130 are arranged symmetrically in the circumferential direction with respect to the d - axis, which is the center of the magnetic pole 101, is shown.

[0020] Here, the permanent magnet 130 has an outer magnet 131, an inner first magnet 132, and an inner second magnet 133, and these are collectively referred to as the permanent magnet 130. The permanent magnet 130 is arranged in two layers in the radial direction. The outer magnet 131 is arranged in the outer layer, and the inner first magnet 132 and the inner second magnet 133 are arranged in the inner layer.

[0021] Also, within the magnetic pole 101, the outer magnet 131, the inner first magnet 132, and the inner second magnet 133 are arranged symmetrically with respect to each other across the d - axis.

[0022] The inner first magnet 132 is arranged on the outer side in the circumferential direction with respect to the outer magnet 131 with respect to the d - axis. Also, the inner second magnet 133 is arranged on the inner side in the radial direction and the inner side in the circumferential direction (the side closer to the d - axis) of the inner first magnet 132.

[0023] The two outer magnets 131 in the outer layer are arranged such that the portion closer to the d - axis is on the inner side in the radial direction. As a result, the two outer magnets 131 in the outer layer are arranged such that the center is convex in the inner side in the radial direction. Similarly, the two inner first magnets 132 and the two inner second magnets 133 in the inner layer are also arranged such that the center is convex in the inner side in the radial direction.

[0024] In the rotor core 120, storage holes are formed that penetrate the rotor core 120 in a direction parallel to the rotation axis CL (axial direction) in order to store the respective permanent magnets 130. Specifically, in the rotor core 120, two outer magnet storage holes 121 for storing the two outer magnets 131 respectively, two inner first magnet storage holes 122 for storing the two inner first magnets 132 respectively, and two inner second magnet storage holes 123 for storing the two inner second magnets 133 respectively are formed.

[0025] Also, a weight reduction hole 126 is formed across the q-axis at the boundary portion between the adjacent magnetic poles 101. The weight reduction hole 126 is formed for weight reduction of the rotor core 120, but also contributes to the formation of the magnetic path described later. The weight reduction hole 126 has a substantially isosceles triangle shape and is formed in a direction such that the apex is on the q-axis and on the outer side in the radial direction. That is, the two hypotenuses 126a face the outer side in the radial direction. In other words, the two hypotenuses 126a are arranged so as to face the inner second magnet storage hole 123.

[0026] Similar to the two outer magnets 131 described above, the two outer magnet storage holes 121 are formed such that the center is convex toward the inner side in the radial direction. Also, each inner second magnet 133 is connected to the inner side in the radial direction of each inner first magnet storage hole 122 and extends from the q-axis side toward the d-axis side and toward the inner side in the radial direction. As a result, the two inner first magnet storage holes 122 and the two inner second magnets 133 are formed such that the center is convex toward the inner side in the radial direction, similar to the two inner first magnets 132 and the two inner second magnets 133 in the two inner layers.

[0027] As a result, a first magnetic path F is formed between the two outer magnet storage holes 121 and the two inner first magnet storage holes 122 and the two inner second magnet storage holes 123, such that the center in the circumferential direction is convex toward the inner side in the radial direction. P1 is formed.

[0028] Also, between the inner first magnet storage holes 122 adjacent to each other among the magnetic poles 101, a second magnetic path F extends in the radial direction along the q-axis and spans the two magnetic poles.P2 is formed. The second magnetic path F P2 is a magnetic path for two magnetic poles 101 adjacent to each other.

[0029] Furthermore, between each inner second magnet housing hole 123 and the weight reduction hole 126, a third magnetic path F P3 is formed.

[0030] The second magnetic path F on one q-axis side P2 , the third magnetic path F P3 , the third magnetic path F symmetric to this with the d-axis in between P3 , and the second magnetic path F on the other q-axis side P2 form one inner magnetic path with the center in the circumferential direction convex toward the inner side in the radial direction.

[0031] The first magnetic path F P1 and the inner magnetic path are magnetic paths of magnetic flux contributing to reluctance torque.

[0032] FIG. 3 is a characteristic curve (torque dimension dependence characteristic curve) showing the influence of the dimensional relationship on torque in the rotor 100 according to the first embodiment. The horizontal axis is the magnetic path width ratio wr (w2 / w1), and the vertical axis is the relative value of torque.

[0033] Here, the magnetic path width ratio wr is the ratio of the width w2 of the third magnetic path F P3 to the width w1 of the second magnetic path F P2 . Also, the torque on the vertical axis is the relative value (%) with respect to the saturation value of the total torque of the magnet torque and the reluctance torque.

[0034] The conditions for creating the curve of this graph are as follows. (1) Assuming the thickness of the outer magnet 131 and the inner first magnet 132 is T1 and the thickness of the inner second magnet 133 is T2, T2 is larger than T1. Also, the thickness ratio t of T2 to T1 is 1.4. (2) The position of the outer magnet housing hole 121 is fixed. Also, the width of the first magnetic path F P1 is fixed. (3) When increasing the thickness of the inner second magnet 133 from T1, the thickness increasing direction is the inner side in the radial direction. Therefore, for the third magnetic path F P3 the increase width is adjusted by changing the position of the hypotenuse 126a of the weight reduction hole 126. Here, when changing the position of the hypotenuse 126a, the position of the weight reduction hole 126 is changed to the inner side in the radial direction or the size of the weight reduction hole 126 is reduced.

[0035] According to the graph shown in FIG. 3, the value of w2 / w1 with respect to the decrease ΔT(%) from the saturation value of torque is as follows.

[0036] When the decrease ΔT(%) is 0.1%, wr is 1.0; when the decrease ΔT(%) is 0.2%, wr is 0.96; when the decrease ΔT(%) is 0.3%, wr is 0.89; when the decrease ΔT(%) is 0.4%, wr is 0.85; when the decrease ΔT(%) is 0.5%, wr is 0.81.

[0037] Note that the value of w2 / w1 mainly affects the width of the magnetic path that generates reluctance torque, while the thickness T2 of the inner second magnet 133 affects the magnet torque. Since the influence of the thickness of the inner second magnet 133 on the characteristics shown in FIG. 3 is small, the above relationship does not substantially change.

[0038] Thus, for example, if wr is 1 or more, the decrease ΔT of torque remains at 0.1% or less, and substantially, the torque value is maintained.

[0039] FIG. 4 is a flowchart showing the procedure of the manufacturing method of the rotor 100 according to the first embodiment. The manufacturing method of the rotor 100 has a manufacturing condition determination step S10 and a manufacturing step S20.

[0040] In the manufacturing condition determination step S10, first, the reference specifications of the rotor 100 are determined (step S11). As a result, the specifications of the rotor shaft 110, the number of permanent magnets 130, the basic arrangement, etc. are determined.

[0041] Next, determine the specifications of the permanent magnet, the rotor core specifications, and the shape of the electromagnetic steel sheet punching (step S12). In step S12, steps S12a to S12e are performed. The details of step S12 will be described below.

[0042] First, determine the specifications of the permanent magnet 130, the shape and dimensions of the magnet housing holes (step S12a). The specifications of the permanent magnet 130 include the material, shape, dimensions, and installation position of the outer magnet 131, the inner first magnet 132, and the inner second magnet 133. The shape and dimensions of the magnet housing holes are the respective shapes and dimensions of the outer magnet housing hole 121, the inner first magnet housing hole 122, and the inner second magnet housing hole 123. Here, the thickness of the inner second magnet 133 is a value larger than the thicknesses of the outer magnet 131 and the inner first magnet 132.

[0043] Next, create a torque dimension-dependent characteristic curve as shown in FIG. 3 (step S12b). That is, create a dependence characteristic of torque with respect to the magnetic path width ratio Wr (w2 / w1), that is, a torque dimension-dependent curve.

[0044] Next, set the allowable reduction rate of torque (step S12c).

[0045] Next, derive the magnetic path width ratio Wr from the torque dimension-dependent curve created in step S12b and the allowable reduction rate of torque according to step S12c, and obtain the width w2 of the third magnetic path F P3 (step S12d). Based on the above results, determine the manufacturing specifications of the rotor core 120 (step S12e). Here, the manufacturing specifications are detailed specifications including the punching shape and dimensions of the electromagnetic steel sheet.

[0046] Next, each step of the manufacturing step S20 will be described in relation to the manufacturing condition determination step S10.

[0047] First, based on the rotor reference specifications obtained in step S11, a rotor shaft 110 is manufactured (S21). The manufacturing of the rotor shaft 110 may be performed, for example, by placing an order with a raw material manufacturer and performing processing after acceptance.

[0048] Next, based on the specifications of the permanent magnet 130 determined in step S12a, the permanent magnet 130 is manufactured (step S22). Here, the manufacturing of the permanent magnet 130 may be by requesting manufacturing from a permanent magnet specialist manufacturer and purchasing.

[0049] Next, based on the specifications of the rotor core 120 in step S12e, electromagnetic steel sheets for lamination are manufactured (step S23), and assembly into the rotor core 120 with a laminated structure is performed (step S24).

[0050] Next, the rotor shaft 110 in step S21, the permanent magnet 130 in step S22, and the rotor core 120 in step S24 are assembled (step S25), and further, attachments such as an inner fan are attached (step S26) to obtain a rotor 100.

[0051] Furthermore, inspection after assembly of the rotor 100 assembled in step S26 is performed (step S27).

[0052] As described above, by increasing the thickness of the inner second magnet 133, the magnet torque increases, and the high torque of the rotating electrical machine 1 can be achieved. Alternatively, the miniaturization of the rotating electrical machine 1 can be achieved by maintaining the torque of the rotating electrical machine 1. Alternatively, the coercive force Hc of the inner second magnet 133 can be lowered.

[0053] [Second Embodiment] FIG. 5 is a partial cross-sectional view showing a rotating electrical machine 1a according to the second embodiment. This embodiment is a modification of the first embodiment. In the following, the description of the common parts with the first embodiment will be omitted, and only the differences will be described.

[0054] The rotor 100a of this embodiment is common to the first embodiment in that the outer magnet 131 and the inner first magnet 132 are arranged symmetrically with respect to each other across the d-axis within each magnetic pole 101. However, instead of the two inner second magnets 133, it has one inner central magnet 134. The inner central magnet 134 is arranged symmetrically in the circumferential direction on the d-axis.

[0055] Similarly, the rotor core 120a also has one inner central magnet housing hole 125 instead of the two inner second magnet housing holes 123. The inner central magnet housing hole 125 is also formed symmetrically in the circumferential direction on the d-axis.

[0056] In this embodiment, the first magnetic path F P1 is formed between the two outer magnet housing holes 121, the two inner first magnet housing holes 122, and one inner central magnet housing hole 125.

[0057] Also, the third magnetic path F P3 is formed between the inner central magnet housing hole 125 and the weight reduction hole 126. Here, let the width of the third magnetic path F P3 be w3.

[0058] While maintaining the width of the first magnetic path F P1 increase the thickness of the inner central magnet 134 to T3, which is larger than T1, toward the radially inner side. The dependence characteristic of the torque of the rotating electrical machine 1 on the ratio of the width w1 of the width w3 at this time shows a tendency similar to the characteristic shown in FIG. 3 described in the first embodiment.

[0059] Therefore, similar to the first embodiment, by setting the ratio of the width w3 to the width w1 to a value for maintaining the reduction width of the torque of the rotating electrical machine 1a within an allowable range, an effect similar to that of the first embodiment can be obtained.

[0060] As described above, according to the embodiment described above, it is possible to provide a rotor and a rotating electrical machine capable of reducing the coercive force of the permanent magnet without accompanying a decrease in torque.

[0061] [Other Embodiments] The embodiments of the present invention have been described above. However, the embodiments are presented as examples and are not intended to limit the scope of the invention. Also, the features of each embodiment may be combined. Furthermore, the embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0062] 1... Rotating electrical machine, 10... Stator, 11... Stator core, 12... Stator slots, 13... Stator teeth, 15... Stator winding, 20... Bearing, 30... Bearing bracket, 40... Frame, 100... Rotor, 101... Magnetic pole, 110... Rotor shaft, 120... Rotor core, 121... Outer magnet accommodation hole, 122... Inner first magnet accommodation hole, 123, 124... Inner second magnet accommodation holes, 125... Inner central magnet accommodation hole, 126... Weight reduction hole, 130... Permanent magnet, 131... Outer magnet, 132... Inner first magnet, 133... Inner second magnet, 134... Inner central magnet, F P1 ... First magnetic path, F P2 ... Second magnetic path, F P3 ... Third magnetic path

Claims

1. A rotor shaft extending in a rotation axis direction; a rotor core attached to the rotor shaft, in which two outer magnet storage holes are formed in a radially outer portion of each magnetic pole so as to form a pair with each other about a d-axis of a magnetic pole center, two inner first magnet storage holes are formed in a radially inner portion of the outer magnet storage holes so as to form a pair with each other about the d-axis, and inner second magnet storage holes are formed radially inward of each of the two inner first magnet storage holes; An outer magnet housed in the outer magnet housing hole; an inner first magnet housed in each of the inner first magnet housing holes and an inner second magnet housed in each of the inner second magnet housing holes; A rotor comprising: The thickness of the inner second magnet is greater than the thickness of the inner first magnet. A rotor characterized by:

2. 2. The permanent magnet rotor according to claim 1, wherein the inner second magnet is provided at each of the magnetic poles and is arranged across the d-axis.

3. The rotor according to claim 1 , characterized in that two of the inner second magnets are provided at each of the magnetic poles and are arranged so as to be connected to the radially inner sides of each of the two inner first magnet storage holes.

4. In the rotor core, one weight reduction hole is formed radially inward of the inner second magnet housing hole in each of the magnetic poles adjacent to each other, When the shortest distance between the inner first magnets in each of the adjacent magnetic poles is w1, and the shortest distance between the inner second magnet storage hole and the weight reduction hole is w2, w2 / w1 is equal to or greater than a predetermined value that satisfies the torque securing condition. A rotor according to any one of claims 1 to 3.

5. 5. The rotor according to claim 4, wherein the predetermined value is one.

6. 4. The rotor according to claim 1, wherein the second inner magnet has a lower coercive force than the first inner magnet.

7. A rotor according to any one of claims 1 to 3; A stator disposed radially outside the rotor core; A rotating electric machine comprising:

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