Rotor, rotary electric machine, and method for manufacturing rotor

Abstract

Provided are a permanent-magnet rotor and a permanent-magnet electric motor in which it is possible to reduce the coercive force of a permanent magnet without reducing torque. According to an embodiment, a rotor 100 comprises: a rotor shaft 110; first magnets 131 that are disposed in line symmetry with respect to a d-axis; second magnets 133 that are disposed radially inward of the first magnets 131; and a rotor core that is attached to the radially outer side of the rotor shaft 110, the rotor core including a region where a permanent magnet is stored, a non-magnetic region, and a bridge, being formed in a shape substantially protruding toward a rotation center axis, being configured such that a plurality of electrodes having flux barrier bands of which the outer peripheral surfaces are linked are disposed so as to be equally divided in a circumferential direction, and having a non-magnetic region in which the outer peripheral surfaces and the permanent magnet are linked. The thickness of the second magnets is greater than the thickness of the first magnets, and the angle formed by the second magnets is greater than the angle formed by the first magnets.

Description

Rotor, rotating electric machine, and method for manufacturing rotor

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

[0002] In most interior permanent magnet rotors, the magnetic poles are arranged symmetrically around the d-axis at the pole's center. To ensure a magnetic path that matches the magnetic field lines of the stator winding, each pole often uses a rotor core composed of nonmagnetic regions and bridges, with a convex flux barrier band formed radially inward. The permanent magnets are housed in these nonmagnetic regions.

[0003] In the flux barrier band, the bridge also functions as a structural member that resists the centrifugal force applied to the region outside the flux barrier band of the permanent magnet rotor during rotation. In this case, providing bridges on both sides of the d-axis is more advantageous in terms of structural strength than providing a single bridge on the d-axis.

[0004] 6 is a partial cross-sectional view of a conventional rotating electric machine, showing one magnetic pole with permanent magnets 25 arranged symmetrically across the d-axis and a portion of the adjacent magnetic pole separated by the q-axis. The permanent magnets 25 are housed in two magnet housing holes 23 in the flux barrier band 21.

[0005] Japanese Patent No. 3769943 Japanese Patent Application Laid-Open No. 2001-186699 Japanese Patent No. 3938726 Japanese Patent Application Laid-Open No. 2012-29351

[0006] As for the torque of the permanent magnet rotor, it is necessary to take into consideration the magnet torque and the reluctance torque.

[0007] The radially outer and inner sides of the flux barrier band 21 form a magnetic path that is convex radially inward at the magnetic pole 101. The radially inner magnetic path of the flux barrier band 21 has a first magnetic path (q-axis magnetic path) between adjacent permanent magnets 25 and a second magnetic path between the flux barrier band 21 and a rotor shaft (not shown), and contributes to the generation of reluctance torque.

[0008] In this situation, if the thickness of the permanent magnet 25 is increased in order to increase the magnet torque, the width of the first magnetic path will become ０ As a result, the flow of magnetic flux in the q-axis magnetic path is restricted, the reluctance torque decreases, and there is a possibility that the torque increase effect will not be achieved.

[0009] Therefore, it is desirable that increasing the thickness of the radially inner permanent magnets does not reduce torque, and that even a portion of the permanent magnets is reduced in coercive force.

[0010] The problem to be solved by the present invention is to provide a permanent magnet rotor and a permanent magnet motor that are capable of reducing the coercive force of the permanent magnet without reducing torque.

[0011] In order to achieve the above-mentioned object, a rotor according to an embodiment of the present invention comprises a rotor shaft extending in the direction of the central axis of rotation; a first magnet extending in the direction of the central axis of rotation and having a rectangular cross-sectional shape, which is arranged line-symmetrically with respect to a d-axis extending perpendicularly from the central axis of rotation when viewed in a cross section perpendicular to the central axis of rotation; a second magnet also having a rectangular cross-sectional shape, which is arranged line-symmetrically with respect to the d-axis radially inward from the first magnet; and a rotor core attached radially outward from the rotor shaft, which includes an area to house the first magnet and the second magnet, a non-magnetic area, and a bridge, and which has a flux barrier band formed in a substantially convex shape toward the central axis of rotation and connecting the outer circumferential surface, and which has a plurality of magnetic poles arranged equally spaced circumferentially; wherein the thickness of the second magnet is greater than the thickness of the first magnet, and the angle formed by the second magnets is greater than the angle formed by the first magnets.

[0012] Fig. 1 is a longitudinal sectional view showing a rotating electric machine according to an embodiment; Fig. 2 is a partial cross sectional view showing a rotating electric machine according to an embodiment; Fig. 3 is a partial cross sectional view showing a modified example of the rotating electric machine according to an embodiment; Fig. 4 is a graph showing the influence of dimensional relationships in a rotor according to an embodiment on torque; Fig. 5 is a flow chart showing the steps of a method for manufacturing a rotor according to an embodiment; Fig. 6 is a partial cross sectional view showing a conventional example of a rotating electric machine;

[0013] Hereinafter, a rotor, a rotating electric machine, and a rotor manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be denoted by common reference numerals, and duplicated explanations will be omitted.

[0014] FIG. 1 is a vertical cross-sectional view showing a rotating electrical machine 1 according to an embodiment.

[0015] The rotating electric machine 1 has 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 50 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 within the rotor core 120. As shown in FIG. 1 , the permanent magnet 130 has an outer magnet 131 and a first magnet 132.

[0017] FIG. 2 is a partial cross-sectional view showing the rotating electrical machine 1 according to the embodiment.

[0018] 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 adjacent stator slots 12. The stator winding 15 is wound around the stator teeth 13.

[0019] The rotor 100 has a plurality of magnetic poles arranged in sequence in the circumferential direction, but FIG. 2 shows one magnetic pole 101 and parts of the magnetic poles adjacent to it on both sides.

[0020] Here, the magnetic pole 101 is an area sandwiched between two q axes extending from the center of rotation CL. Figure 2 shows 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.

[0021] Here, the permanent magnet 130 includes a first magnet 131 and a second magnet 132 , which are collectively referred to as the permanent magnet 130 .

[0022] Within the magnetic pole 101, a first magnet 131 and a second magnet 132 are arranged symmetrically with respect to the d-axis.

[0023] The first magnet 131 is disposed circumferentially outward of the outer magnet 131 with respect to the d-axis. The second magnet 132 is disposed radially inward and circumferentially inward (closer to the d-axis) of the first magnet 131. The angle Θ between the second magnets 132 is ２ is the angle Θ between the first magnets 131 １ are arranged to be larger than

[0024] Angle Θ between the second magnets 132 ２ is the angle Θ between the first magnets 131 １ The two first magnets 131 and the two second magnets 132 are arranged so that their centers are convex inward in the radial direction. In other words, instead of a configuration with one permanent magnet in the radial direction like the conventional permanent magnet 25 shown in Figure 6, this configuration is made up of two permanent magnets 130, the first magnet 131 and the second magnet 132, and they are arranged so that they form a smooth curve that is convex inward in the radial direction.

[0025] The rotor core 120 includes two outer magnet storage holes 121 and two second magnet storage holes 122, which are areas for storing the first magnet 131 and the second magnet 132, respectively, as well as non-magnetic areas and bridges, and is formed in a generally convex shape toward the rotation center axis CL (Figure 1), with a flux barrier band 121 connecting the outer peripheral surface 120s.

[0026] Additionally, weight-reducing holes 126 are formed across the q-axis at the boundary between adjacent magnetic poles 101. The weight-reducing holes 126 are formed to reduce the weight of the rotor core 120, but also contribute to the formation of a magnetic path, which will be described later. The weight-reducing holes 126 are roughly shaped like an isosceles triangle, and are oriented so that their vertices are on the q-axis and radially outward. That is, the two hypotenuses 126a face radially outward. In other words, the two hypotenuses 126a are arranged to face the inner second magnet storage holes 123.

[0027] Each second magnet hole 123 is connected to the radially inner side of its corresponding first magnet storage hole 122 and extends from the q-axis side to the d-axis side and radially inward. As a result, the two first magnet storage holes 122 and the two second magnet holes 123 are formed so that their centers are convex radially inward, as described above.

[0028] As a result, between the first magnet housing holes 122 of the magnetic poles 101 adjacent to each other, a first magnetic path F extends in the radial direction along the q axis and straddles the two magnetic poles. Ｐ１ The first magnetic path F Ｐ１ is the magnetic path for two adjacent magnetic poles 101. Here, the first magnetic path F Ｐ１ The width of w １ Let's say.

[0029] Furthermore, a second magnetic path F is formed between each of the second magnet storage holes 123 and the weight-reducing holes 126. Ｐ２ Here, the distance between the second magnet storage hole 123 and the weight-reducing hole 126, i.e., the shortest distance, is defined as w ２ Let's say.

[0030] The first magnetic path F on the q-axis side Ｐ１ , second magnetic path F Ｐ２ , a second magnetic path F symmetrical to the d-axis Ｐ２ , the first magnetic path F on the other q-axis side Ｐ１ forms one inner magnetic path whose center is convex radially inward.

[0031] This inner magnetic path becomes the magnetic path of the magnetic flux that contributes to the reluctance torque.

[0032] 3 is a partial cross-sectional view showing a modified example of the rotating electric machine according to the embodiment. In this modified example, outer magnet storage holes 125 are formed radially outward of the flux barrier band 121, line-symmetrically across the d-axis, and each store an outer magnet 133. In this way, the present embodiment, which relates to the radially inner side of the flux barrier band 121, can also be applied when permanent magnets are arranged in multiple layers.

[0033] FIG. 4 is a graph showing the effect of the dimensional relationship on torque in the rotor 100 according to the embodiment. The horizontal axis represents the width ratio wr (w ２ / w １ ), the vertical axis is the relative value of torque.

[0034] Here, the width ratio wr is the width of the third magnetic path F Ｐ３ Width of ２ The second magnetic path F Ｐ２ Width of １ The torque on the vertical axis is the relative value (%) of the total torque of the magnet torque and reluctance torque to its saturation value.

[0035] The conditions for creating the curves of this graph are as follows:

[0036] (1) If the thickness of the outer magnet 131 and the first magnet 131 is T2 and the thickness of the second magnet 132 is T2, T2 is greater than T1. Furthermore, the thickness ratio t of T2 to T1 is 1.4.

[0037] (2) The position of the outer magnet storage hole 121 is fixed. Ｐ１ The width is also fixed.

[0038] (3) When the thickness of the second magnet 132 is increased from T1, the direction of increase in thickness is inward in the radial direction. Therefore, the third magnetic path F Ｐ３ The width of the weight reduction hole 126 is adjusted by changing the position of the oblique side 126a of the weight reduction hole 126. Here, changing the position of the oblique side 126a involves changing the position of the weight reduction hole 126 in the radial direction or changing the size of the weight reduction hole 126.

[0039] According to the graph shown in FIG. 4, the torque decrease ΔT (%) from the saturation value of the torque w ２ / w １ The values ​​of are as follows:

[0040] When the decrease ΔT (%) is 0.1%, wr is 1, when the decrease ΔT (%) is 0.2%, wr is 0.95, when the decrease ΔT (%) is 0.3%, wr is 0.9, when the decrease ΔT (%) is 0.4%, wr is 0.86, and when the decrease ΔT (%) is 0.5%, wr is 0.84.

[0041] In this way, for example, if wr is 1 or more, the torque decrease ΔT remains at 0.1% or less, and the torque value is almost maintained.

[0042] FIG. 5 is a flowchart showing the steps of a method for manufacturing the rotor 100 according to the first embodiment.

[0043] The manufacturing method of the rotor 100 includes a manufacturing condition determination step S10 and a manufacturing step S20.

[0044] In the manufacturing condition determination step S10, first, the standard 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.

[0045] Next, the detailed specifications of the rotor 100 are determined, i.e., the permanent magnets, rotor core specifications, and punched shapes of the electromagnetic steel sheets are determined (step S12). In step S12, steps S12a to S12e are performed. Details of step S12 will be described below.

[0046] First, the specifications of the permanent magnet 130 and the shape and dimensions of the magnet storage hole are determined (step S12a). The specifications of the permanent magnet 130 include the material, shape, dimensions, and installation position of the outer magnet 131, first magnet 132, and second magnet 132. The shape and dimensions of the magnet storage hole are the respective shapes and dimensions of the outer magnet storage hole 121, first magnet storage hole 122, and inner second magnet storage hole 123. Here, the thickness of the second magnet 132 is greater than the thicknesses of the outer magnet 131 and first magnet 132.

[0047] Next, a dimension-dependent characteristic curve of torque as shown in FIG. 4 is created (step S12b). That is, the magnetic path width ratio Wr (w ２ / w １ ) is used to create a torque dependency curve, i.e., a torque dimension dependency curve.

[0048] Next, the allowable torque decrease rate is set (step S12c).

[0049] Next, the magnetic path width ratio Wr is derived from the torque dimension dependency curve created in step S12b and the allowable torque reduction rate in step S12c, and the third magnetic path F Ｐ３ Width of ２ is obtained (step S12d).

[0050] Based on the above results, the manufacturing specifications for the rotor core 120 are determined (step S12e). Here, the manufacturing specifications are detailed specifications including the punched shape and dimensions of the electromagnetic steel sheets.

[0051] Next, each step of the manufacturing step S20 will be described in relation to the manufacturing condition determination step S10.

[0052] First, the rotor shaft 110 is manufactured based on the rotor reference specifications obtained in step S11 (S21). The rotor shaft 110 may be manufactured, for example, by placing an order with a material manufacturer and then processing the material after receipt.

[0053] Next, the permanent magnet 130 is manufactured based on the specifications of the permanent magnet 130 determined in step S12a (step S22). Here, the permanent magnet 130 may be manufactured by outsourcing to a specialized permanent magnet manufacturer or by purchasing.

[0054] Next, based on the specifications of the rotor core 120 in step S12e, electromagnetic steel sheets for lamination are manufactured (step S23), and assembled into the rotor core 120 having a laminated structure (step S24).

[0055] Next, the rotor shaft 110 in step S21, the permanent magnets 130 in step S22, and the rotor core 120 in step S24 are assembled (step S25), and further accessories such as an inner fan are attached (step S26), thereby obtaining the rotor 100.

[0056] Furthermore, a post-assembly inspection of the rotor 100 assembled in step S26 is carried out (step S27).

[0057] As described above, the configuration using one permanent magnet in the radial direction, as in the permanent magnet 25 of the conventional example, is changed to a configuration using two permanent magnets 130, the first magnet 131 and the second magnet 132, and by making the angle between the second magnets larger than the angle between the first magnets, the degree of convexity toward the inside in the radial direction is alleviated, and the first magnetic path F Ｐ１The thickness of the second magnet 132 on the radially inner side can be increased without affecting the magnetic field. In addition, by increasing the thickness of the second magnet 132, the magnet torque increases, and the torque of the rotating electric machine 1 can be increased. Alternatively, the rotating electric machine 1 can be made smaller while maintaining the torque of the rotating electric machine 1. Alternatively, the coercive force Hc of the second magnet 132 can be reduced.

[0058] According to the embodiments described above, it is possible to provide a rotor and a rotating electric machine that can reduce the coercive force of the permanent magnet without reducing torque.

[0059] [Other Embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. Furthermore, the embodiments may be implemented in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0060] DESCRIPTION OF SYMBOLS 1... rotating electric machine, 10... stator, 11... stator core, 12... stator slot, 13... stator teeth, 15... stator winding, 20... rotor, 21... rotor core, 22... flux barrier band, 23... magnet storage hole, 24... bridge, 25... permanent magnet, 31... bearing, 32... bearing bracket, 33... frame, 100... rotor, 101... magnetic pole, 110... rotor shaft, 120 , 120a...rotor core, 120s...outer peripheral surface, 121...flux barrier band, 122...inner magnet first storage hole, 122a...bridge adjacent non-magnetic portion, 123...inner magnet second storage hole, 123a...bridge adjacent non-magnetic portion, 124...bridge, 125...outer magnet storage hole, 126...weight reduction hole, 130...permanent magnet, 131...first magnet 131...second magnet, 133...outer magnet, F Ｐ１ ...first magnetic path, F Ｐ２ ...Second magnetic path

Claims

1. A rotor shaft extending in the direction of the rotation center axis, a first magnet extending in the direction of the rotation center axis and arranged symmetrically with respect to the d-axis extending perpendicularly from the rotation center axis when viewed in a cross-section perpendicular to the rotation center axis and having a rectangular cross-sectional shape, a second magnet arranged symmetrically with respect to the d-axis radially inside the first magnet and having a rectangular cross-sectional shape, a plurality of magnetic poles circumferentially equally spaced and having a flux barrier band attached to the outside in the radial direction of the rotor shaft and including a region for housing the first magnet and the second magnet, a non-magnetic region, and a bridge, and formed in a substantially convex shape toward the rotation center axis and connecting the outer peripheral surfaces. The thickness of the second magnet is larger than the thickness of the first magnet, and the angle formed by the second magnets is larger than the angle formed by the first magnets. The rotor is characterized by the above.

2. The rotor according to claim 1, characterized by having the non-magnetic region connecting the outer peripheral surface and the first magnet.

3. In the rotor core, one weight-reducing hole is formed radially inside the inner second magnet housing hole which is a region for housing the second magnet in each of the adjacent magnetic poles, and the shortest distance between the first magnets in each of the adjacent magnetic poles is defined as a distance w １ and the shortest distance between the weight-reducing hole and the inner second magnet housing hole is defined as a distance w ２ When this is the case, the distance w ２ is larger than the distance w １ The rotor according to claim 1 or claim 2, characterized in that.

4. The rotor according to claim 1 or claim 2, further comprising a permanent magnet arranged symmetrically with respect to the d-axis when viewed in the cross-section and arranged outside the flux barrier band in the radial direction.

5. A rotating electrical machine comprising the rotor according to claim 1 or claim 2 and a stator arranged outside the rotor core in the radial direction.

6. A method for manufacturing a rotor, comprising a reference specification determination step for determining a reference specification of the rotor, a detailed specification determination step for determining a detailed specification of the rotor based on the reference specification, and a manufacturing step for manufacturing the rotor based on the detailed specification. The detailed specification determination step includes a step of creating a dimensional dependence characteristic curve of torque, a step of setting an allowable reduction rate of the torque, and a step of determining a magnetic path width ratio based on the dimensional dependence characteristic curve and the allowable reduction rate.

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