Rotor structure of dynamo-electric motor

Abstract

To provide a rotor structure of a dynamo-electric motor, capable of preventing deterioration of a producibility by securing smooth insertion of a magnet into a magnet embedded hole in a rotor core in manufacturing of the dynamo-electric motor, and suppressing an eddy current loss at an operation of the dynamo-electric motor by reducing a contact are with a front surface of the magnet and an inner surface of the magnet embedded hole.SOLUTION: A rotor structure of a dynamo-electric motor comprises: a rotor core 7 having a plurality of magnet embedded holes 8 extended in a state of being penetrated along a shaft line C passing a center of a rotational shaft 2; and a plurality of magnets 9 that are embedded into the plurality of magnet embedded holes 8 so as to be inserted. Each magnet embedded hole 8 includes a first holding surface 11 and a second holding surface 12 that hold each magnet 8 while nipping it. Each of the first holding surface 11 and the second holding surface 12 is contacted to each magnet 8 held in an arbitrary cross section orthogonal to the shaft line C, and includes a first contact part 11a and a second contact part 12a that are formed so as to be continued along the shaft line C.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotor structure of an electric motor, and more particularly to a rotor structure applied to an interior permanent magnet synchronous motor (IPMSM) in which magnets are embedded in a rotor core. [Background technology]

[0002] Conventionally, rotor structures of this type are known, for example, as described in Patent Documents 1 and 2. The rotor structure of Patent Document 1 has a rotor core formed by concentrically stacking a large number of thin electromagnetic steel plates, each formed into an annular shape, and a plurality of magnets embedded in the rotor core. The rotor core has magnet embedding holes for embedding the magnets, which extend through the rotor core in the axial direction and have a cross section of a predetermined shape. Meanwhile, the magnets have approximately the same length as the axial direction of the rotor core, and are formed with a rectangular cross section.

[0003] In a motor having a rotor with magnets embedded in each magnet embedding hole, eddy currents are likely to occur in the magnets of the rotor when the rotor rotates at high speed. In particular, in the rotor structure described above, the surface of the magnet comes into surface contact with the inner surface of the magnet embedding hole, increasing the contact area between the two, which can result in large eddy current loops in the rotor and increase losses due to the eddy currents (hereinafter referred to as "eddy current loss").

[0004] On the other hand, in Patent Document 2, in order to reduce the above-mentioned eddy current loss, the rotor core is configured as follows. That is, this rotor core is configured by stacking a plurality of first core members and second core members, each made of a thin electromagnetic steel sheet formed into an annular shape. Specifically, the first core member has a first magnet hole that is slightly larger than the cross section of the magnet, while the second core member has a second magnet hole that is provided at a position corresponding to the first magnet hole and has a plurality of protrusions that protrude inward. And, the rotor core is configured, for example, by stacking a large number of first core members and one second core member that is arranged near the center of the rotor core in the axial direction.

[0005] A magnet embedding hole for embedding a magnet in the rotor core is formed by the first magnet holes formed by the multiple first core members and the second magnet hole formed by the single second core member, and when a magnet is embedded in this magnet embedding hole, only the multiple protrusions of the second magnet hole in the second core member come into contact with the magnet. As a result, in the rotor structure of Patent Document 2, the contact area between the surface of the magnet and the inner surface of the magnet embedding hole is smaller than in Patent Document 1, reducing eddy current loss during motor operation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-182358 A [Patent Document 2] JP 2013-110827 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the rotor structure of Patent Document 2 described above has the following problem when inserting and embedding magnets in the magnet embedding holes of the rotor core during motor manufacturing. That is, when an end of a magnet is inserted from one opening of the magnet embedding hole and the magnet is pushed further into the magnet embedding hole, the magnet may hit a protruding portion of the second magnet hole in the second core member and become stuck halfway through the insertion into the magnet embedding hole. In this case, the process of inserting magnets into the magnet embedding holes of the rotor core is time-consuming, and there is a risk of reducing the manufacturing efficiency of the motor.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide an electric motor rotor structure that can ensure smooth insertion of magnets into magnet embedding holes in a rotor core when manufacturing an electric motor, thereby preventing a decrease in manufacturing efficiency, and that can suppress eddy current loss when the motor is operating by reducing the contact area between the surface of the magnet and the inner surface of the magnet embedding hole. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the invention of claim 1 is a rotor structure of an electric motor having a rotor through which a rotating shaft passes and which is fixed to the rotating shaft, comprising a rotor core having a plurality of magnet embedding holes extending in a penetrating state along an axis passing through the center of the rotating shaft, and a plurality of magnets embedded in a state inserted into the plurality of magnet embedding holes, each of the plurality of magnet embedding holes having a first retaining surface and a second retaining surface which face each other with the embedded magnet therebetween and hold the magnet in a sandwiched state, and the first retaining surface and the second retaining surface are in point contact with the held magnet at an arbitrary cross section which is an arbitrary cross section perpendicular to the axis, and each have a first abutment portion and a second abutment portion which are formed so as to be continuous along the axis.

[0010] According to this configuration, the rotor structure of an electric motor having a rotor fixed to a rotating shaft includes a rotor core having a plurality of magnet embedding holes, and a plurality of magnets embedded by being inserted into the magnet embedding holes. Each of the plurality of magnet embedding holes extends in a penetrating state along an axis passing through the center of the rotating shaft, and has a first holding surface and a second holding surface that face each other with the embedded magnet between them. Furthermore, these first holding surface and second holding surface make point contact with the held magnet at an arbitrary cross section that is an arbitrary cross section perpendicular to the axis, and each have a first abutment portion and a second abutment portion that are formed so as to be continuous along the axis.

[0011] When inserting a magnet into a magnet embedding hole in a rotor core during manufacture of an electric motor, an end of the magnet is inserted into one opening of the magnet embedding hole. In this case, a first abutment portion of a first retaining surface of the magnet embedding hole and a second abutment portion of a second retaining surface of the magnet embedding hole contact ends of the surface of the magnet. Then, by pushing the magnet into the magnet embedding hole, the entire magnet is inserted into the magnet embedding hole while both abutment portions of the first retaining surface and the second retaining surface, i.e., the first abutment portion and the second abutment portion, are in contact with the surface of the magnet. In this way, smooth insertion of the magnet into the magnet embedding hole in the rotor core can be ensured during manufacture of the electric motor, thereby preventing a decrease in the manufacturing efficiency of the electric motor.

[0012] Furthermore, when the magnet is embedded in the rotor core, the first contact portion of the first holding surface and the second contact portion of the second holding surface of the magnet embedding hole come into point contact with the surface of the magnet in any cross section perpendicular to the axis. This makes it possible to significantly reduce the contact area between the magnet surface and the inner surface of the magnet embedding hole compared to when the magnet is in surface contact with the inner surface of the magnet embedding hole, thereby suppressing eddy current loss when the motor is rotating.

[0013] The invention of claim 2 is characterized in that, in the rotor structure of the electric motor described in claim 1, the first abutment portion is composed of one or more first abutment portions, and the second abutment portion is composed of one or more second abutment portions.

[0014] According to this configuration, when the first and second holding surfaces have one abutment portion, the contact area between the surface of the magnet and the inner surface of the magnet embedding hole can be minimized compared to when the first and second holding surfaces have multiple abutment portions. Also, when at least one of the first and second holding surfaces has multiple abutment portions, the magnet can be inserted relatively stably into the magnet embedding hole while being supported by the multiple abutment portions. The number of first abutment portions of the first holding surface and the number of second abutment portions of the second holding surface may be the same or different.

[0015] The invention of claim 3 is characterized in that, in the rotor structure of the electric motor described in claim 1, the first retaining surface and the second retaining surface are formed in an arc shape that is convexly curved in one direction, either radially inward, which is the axis side, or radially outward, which is the opposite side to the axis, in an arbitrary cross section, and are configured as a convex outer surface located on the outside of the convex direction, and a convex inner surface located on the inside of the convex direction, respectively; the magnet is formed in an arc shape that is convexly curved in one direction as a whole in an arbitrary cross section, and has an outer opposing magnet surface facing the convex outer surface, and an inner opposing magnet surface facing the convex inner surface, and the convex outer surface is set to have a larger radius of curvature than the outer opposing magnet surface, so that the apex of the convex outer surface functions as a single first abutment portion, and the convex inner surface is set to have a smaller radius of curvature than the inner opposing magnet surface, so that the apex of the convex inner surface functions as a single second abutment portion.

[0016] According to this configuration, the first and second holding surfaces are formed in an arc shape that is convexly curved toward either the radially inward or radially outward in any cross section perpendicular to the axis, and are configured as the convex outer and convex inner surfaces, respectively. The magnet is formed in an arc shape that is convexly curved as a whole in any cross section, similar to the magnet embedding hole having the first holding surface (convex outer surface) and the second holding surface (convex inner surface), and has an outer opposing magnet surface and an inner opposing magnet surface that face the convex outer surface and the convex inner surface, respectively. The convex outer surface is set to have a larger radius of curvature than the outer opposing magnet surface, while the convex inner surface is set to have a smaller radius of curvature than the inner opposing magnet surface. This allows the top of the convex outer surface to function as a single first contact portion in the magnet embedding hole, and the top of the convex inner surface to function as a single second contact portion.

[0017] The invention of claim 4 is characterized in that, in the rotor structure of the electric motor described in claim 1, each of the multiple magnet embedding holes further has two engaging portions that make point contact at an arbitrary cross section and are formed continuously along the axis so as to sandwich the magnet from both sides in a direction approximately perpendicular to the direction in which the magnet is sandwiched by the first retaining surface and the second retaining surface.

[0018] According to this configuration, each of the multiple magnet embedding holes further has the two locking parts. These locking parts are formed to make point contact in any cross section perpendicular to the axis and to be continuous along the axis so as to sandwich the magnet from both sides in a direction substantially perpendicular to the direction in which the magnet is sandwiched by the first and second holding surfaces of each magnet embedding hole. Since each magnet embedding hole has the two locking parts in addition to the first abutment part of the first holding surface and the second abutment part of the second holding surface, the magnet embedded in the magnet embedding hole is supported from all sides. This allows the magnet to be inserted smoothly into the magnet embedding hole and the magnet embedded in the magnet embedding hole to be held in a stable state.

[0019] The invention of claim 5 is characterized in that, in the rotor structure of the electric motor described in claim 1, the multiple magnet embedding holes are arranged in groups of two or more magnet embedding holes, with each group being arranged at a predetermined angle around the axis, and the magnet embedding holes of each group are arranged in the circumferential direction around the axis and / or in the radial direction of the axis.

[0020] According to this configuration, two or more magnet embedding holes are grouped into a set, and the magnet embedding holes are arranged in the rotor core at each predetermined angle around the axis. In this case, each of the set of magnet embedding holes is arranged in the circumferential direction around the axis, and by embedding a magnet in each magnet embedding hole, magnetic poles can be set at each predetermined angle in the circumferential direction of the rotor. Also, each of the set of magnet embedding holes is arranged in the radial direction of the axis, and a magnet is embedded in each magnet embedding hole, i.e., the magnets are arranged in multiple layers in the radial direction, which makes it easy to increase the reluctance torque of each magnetic pole of the rotor.

[0021] The invention according to claim 6 is the rotor structure for an electric motor according to any one of claims 1 to 5, wherein one or a plurality of magnets are embedded in each of the plurality of magnet embedding holes.

[0022] With this configuration, when embedding one magnet in each of the multiple magnet embedding holes, it is possible to insert one magnet into each magnet embedding hole and embed the magnets in all of the magnet embedding holes relatively easily. Also, when multiple magnets are embedded in each of the multiple magnet embedding holes, the eddy currents generated when the motor rotates can be made smaller than when only one magnet is embedded, thereby suppressing eddy current loss.

[0023] [Brief description of the drawings]

[0024] [Figure 1] 1A and 1B are diagrams for explaining a motor to which a rotor structure according to a first embodiment of the present invention is applied, in which (a) is a schematic diagram of the motor, (b) is a cross-sectional diagram partially showing the rotor and shaft when the motor in (a) is cut along line AA, and (c) is an enlarged diagram showing the magnet and magnet embedding hole on the right side of the rotor shown in (b). [Diagram 2] 1(a) is an enlarged view of the magnet embedding hole similar to that in FIG. 1(c), (b) is a cross-sectional view of the magnet and magnet embedding hole in (a) taken along line BB, showing the state where the tip of the magnet is inserted into the opening of the magnet embedding hole, and (c) shows the state where the magnet has been pushed in from the state shown in (b), completing its insertion into the magnet embedding hole. [Diagram 3] FIG. 1(b) is a diagram for explaining a rotor structure according to a second embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of the rotor and an enlarged view of a magnet and magnet embedding hole on the right side. [Figure 4] FIG. 1(b) is a diagram for explaining a rotor structure according to a third embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of the rotor and an enlarged view of a magnet and magnet embedding hole on the right side. [Diagram 5] FIG. 1(b) is a diagram for explaining a rotor structure according to a fourth embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of the rotor and an enlarged view of the magnet and magnet embedding hole on the right side. [Figure 6] FIG. 13 is a diagram for explaining a rotor structure according to a fifth embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of the rotor and an enlarged view of a magnet and magnet embedding hole on the right side. [Figure 7] FIG. 15 is a diagram for explaining a rotor structure according to a sixth embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of the rotor and an enlarged view of multiple magnets and magnet embedding holes on the right side. [Figure 8] FIG. 19 is a diagram for explaining a rotor structure according to a seventh embodiment of the present invention, corresponding to FIGS. 1(b) and (c), and showing a cross-sectional view of a part of a rotor and an enlarged view of a plurality of magnets and magnet embedding holes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1(a) shows a schematic diagram of a motor to which a rotor structure according to a first embodiment of the present invention is applied. As shown in Figs. 1(a) and 1(b), the motor 1 (electric motor) is an interior permanent magnet synchronous motor (IPMSM), and includes a shaft 2 (rotating shaft) having a predetermined length and diameter, a rotor 3 through which the shaft 2 passes and which is fixed to the shaft 2, a stator 4 provided in a state surrounding the outer periphery of the rotor 3, and a frame 5 which covers the rotor 3 and the stator 4 and fixes the stator 4 to its inner periphery. In the following description, a line passing through the center of the shaft 2 and extending in the longitudinal direction of the shaft 2 is referred to as an "axis C."

[0026] Fig. 1(b) partially shows the rotor 3 and shaft 2 when the motor 1 in Fig. 1(a) is cut along line AA. As shown in Fig. 1(b), the rotor 3 includes a rotor core 7 fixed with the shaft 2 passing through its center, and a plurality of permanent magnets 9 (hereinafter simply referred to as "magnets") (only two are shown in Fig. 1(b)) embedded in a plurality of magnet embedding holes 8 (only two are shown in Fig. 1(b)) provided in the rotor core 7.

[0027] The rotor core 7 is constructed by stacking a number of core members 7a made of thin electromagnetic steel plates. Specifically, each core member 7a has a shaft hole 7b in the center through which the shaft 2 passes, and is formed into a doughnut-like shape when viewed from above. Each core member 7a also has a number of magnet embedding holes 8 formed therein, each having a predetermined shape as shown in Figs. 1(b) and (c).

[0028] As shown in Fig. 1(b), the rotor core 7 has pairs of magnet embedding holes 8, 8 arranged in the circumferential direction at predetermined angles (e.g., 60 degrees) around the axis C. A magnet 9 is inserted and embedded in each magnet embedding hole 8. Since the two magnet embedding holes 8, 8 shown in Fig. 1(b) are symmetrical, the following explanation will focus on the magnet embedding hole 8 on the right side.

[0029] Fig. 1(c) shows an enlarged view of the magnet 9 and magnet embedding hole 8 on the right side of the rotor 3 shown in Fig. 1(b). For convenience of illustration, the magnet 9 shown in Fig. 1(c) is indicated by a two-dot chain line.

[0030] As shown in FIG. 1(c), the magnet embedding hole 8 has an outer retaining surface 11 (first retaining surface) located on the radial outside of the rotor core 7 (upper side in FIG. 1(c)) and an inner retaining surface 12 (second retaining surface) located on the radial inside (lower side in FIG. 1(c)), and these outer retaining surface 11 and inner retaining surface 12 face each other with the magnet 9 between them. Furthermore, these outer retaining surface 11 and inner retaining surface 12 are formed in an arc shape that curves convexly toward the inside of the magnet embedding hole 8, and each apex 11a (first abutment portion) and apex 12a (second abutment portion) are formed so as to make point contact with the magnet 9 in an arbitrary cross section that is an arbitrary cross section perpendicular to the axis C, and to continue along the axis C.

[0031] Furthermore, the magnet embedding hole 8 has left and right locking portions 13L and 13R that protrude inward on both the left and right sides of the inner holding surface 12 and hold the magnet 9 from both sides in a direction (left and right direction in FIG. 1(c)) substantially perpendicular to the direction in which the magnet 9 is held by the outer holding surface 11 and the inner holding surface 12. These left and right locking portions 13L and 13R are in point contact with the magnet 9 in any cross section and are formed so as to be continuous along the axis C.

[0032] As shown in Fig. 1(a), the magnet 9 has a length substantially equal to the axial length of the rotor core 7, and as shown in Figs. 1(b) and 1(c), the cross section is formed in a rectangular shape and is formed in a rectangular parallelepiped shape having a predetermined size. As shown in Fig. 1(c), the magnet 9 has an outer magnet surface 9a and an inner magnet surface 9b located on the outer and inner sides, respectively, of the rotor core 7 in the radial direction, and a left magnet surface 9c and a right magnet surface 9d connected thereto. When the magnet 9 is embedded in the magnet embedding hole 8, the apex 11a, the apex 12a, the left locking portion 13L and the right locking portion 13R of the magnet embedding hole 8 are in point contact with the outer magnet surface 9a, the inner magnet surface 9b, the left magnet surface 9c and the right magnet surface 9d of the magnet 9, respectively, in any cross section, and are in line contact in the longitudinal direction of the axis C.

[0033] Here, with reference to Fig. 2, a method for inserting magnets 9 into magnet embedding holes 8 of rotor core 7 will be described. Fig. 2(a) shows magnets 9 and magnet embedding holes 8 corresponding to Fig. 1(c) described above, and Fig. 2(b) is a cross-sectional view of magnets 9 and magnet embedding holes 8 in (a) taken along line BB, showing the state in which the tip of magnet 9 is inserted into the opening of magnet embedding hole 8.

[0034] As shown in Fig. 2(b), when inserting the magnet 9 into the magnet embedding hole 8, first, the tip of the magnet 9 is inserted into one opening (the left in Fig. 2(b)) of the magnet embedding hole 8. In this case, at the tip of the magnet 9, the outer magnet surface 9a and the inner magnet surface 9b contact the tops 11a and 12a of the outer holding surface 11 and the inner holding surface 12 of the magnet embedding hole 8, respectively, and the left magnet surface 9c and the right magnet surface 9d contact the left locking portion 13L and the right locking portion 13R of the magnet embedding hole 8, respectively.

[0035] 2(b), the magnet 9 is pushed into the magnet embedding hole 8 as indicated by the outline arrow, and the entire magnet 9 is inserted into the magnet embedding hole 8 as indicated by the outline arrow in FIG. 2(c), completing the insertion of the magnet 9. When inserting the magnet 9 into the magnet embedding hole 8, the outer magnet surface 9a, inner magnet surface 9b, left magnet surface 9c, and right magnet surface 9d of the magnet 9 come into contact with the top 11a of the outer holding surface 11, the top 12a of the inner holding surface 12, the left locking portion 13L, and the right locking portion 13R of the magnet embedding hole 8, respectively, so that the magnet 9 is inserted while being supported from all sides by the magnet embedding hole 8.

[0036] Furthermore, as described above, after inserting the magnet 9 into the magnet embedding hole 8, the gap between the magnet 9 and the magnet embedding hole 8 may be filled with synthetic resin. In this case, by filling the gap with molten synthetic resin and hardening it, the magnet 9 can be more stably held in a predetermined position within the magnet embedding hole 8, and by suppressing bending stress that is likely to occur in the magnet 9, particularly when the motor 1 is rotating, damage to the magnet 9 can be prevented.

[0037] As described above, the rotor structure of the first embodiment ensures smooth insertion of magnets 9 into magnet embedding holes 8 in rotor core 7 during manufacture of motor 1, which prevents a decrease in the manufacturing efficiency of motor 1, unlike the conventional case in which magnets get stuck when inserted. Also, compared to the conventional case in which the magnets make surface contact with the inner surface of the magnet embedding hole, the contact area between the surface of magnet 9 and the inner surface of magnet embedding hole 8 can be significantly reduced, which results in suppression of eddy current loss when motor 1 rotates.

[0038] Fig. 3 shows a rotor structure according to a second embodiment of the present invention. In the following description of each embodiment, differences from the first embodiment will be mainly described, and components similar to those in the first embodiment will be given the same reference numerals and detailed description thereof will be omitted.

[0039] 3, in the second embodiment, both the outer holding surface 11 and the inner holding surface 12 of the magnet embedding hole 8A have two arcs that curve convexly inward, and the apexes of each are in contact with the magnet 9. Specifically, the two apexes 11b, 11b of the outer holding surface 11 of the magnet embedding hole 8A and the two apexes 12b, 12b of the inner holding surface 12 are in point contact with the outer magnet surface 9a and the inner magnet surface 9b of the magnet 9, respectively, in an arbitrary cross section.

[0040] According to the rotor structure of the second embodiment, it is possible to obtain the same actions and effects as those of the first embodiment. In particular, when inserting the magnet 9 into the magnet embedding hole 8A, the magnet 9 can be inserted relatively stably while the outer magnet surface 9a is supported by the two apexes 11b, 11b and the inner magnet surface 9b is supported by the two apexes 12b, 12b.

[0041] 4 shows a rotor structure according to a third embodiment of the present invention. As shown in the figure, in this third embodiment, the outer holding surface 11 of the magnet embedding hole 8B has eight arcs that are curved convexly inward, while the inner holding surface 12 has two arcs that are curved convexly inward, and the apex of each arc is in contact with the magnet 9. Specifically, the eight apexes 11c of the outer holding surface 11 of the magnet embedding hole 8B and the two apexes 12c of the inner holding surface 12 are in point contact with the outer magnet surface 9a and the inner magnet surface 9b of the magnet 9, respectively, in an arbitrary cross section.

[0042] According to the third embodiment, it is possible to obtain the same actions and effects as the first embodiment. In particular, when inserting the magnet 9 into the magnet embedding hole 8B, the magnet 9 can be inserted more stably because the outer magnet surface 9a of the magnet 9 is supported by eight apexes 11c and the inner magnet surface 9b is supported by two apexes 12c, 12c.

[0043] Fig. 5 shows a rotor structure according to a fourth embodiment of the present invention. As shown in the figure, in this fourth embodiment, the magnet embedding hole 8C is formed as a whole so as to be curved convexly toward the radially inward direction (the lower side of Fig. 5) on the axis C side. Specifically, the outer retaining surface 11 (convex inner surface) and the inner retaining surface 12 (convex outer surface) of the magnet embedding hole 8C are both formed in an arc shape that is curved convexly toward the radially inward direction and have a predetermined radius of curvature.

[0044] On the other hand, unlike the magnet 9 of the first to third embodiments, which has a rectangular cross section, the magnet 10 of the fourth embodiment is formed in an arc shape that is curved convexly radially inward, that is, toward the axis C, as shown in Fig. 5. Specifically, the magnet 10 has an outer magnet surface 10a (inner facing magnet surface) and an inner magnet surface 10b (outer facing magnet surface), both of which are curved convexly radially inward, as well as a left magnet surface 10c and a right magnet surface 10d that are continuous with these.

[0045] Additionally, the outer magnet surface 10a and inner magnet surface 10b of the magnet 10 face the outer holding surface 11 and inner holding surface 12 of the magnet embedding hole 8C, respectively, and have a predetermined radius of curvature. Specifically, the inner holding surface 12 of the magnet embedding hole 8C is set to have a larger radius of curvature than the inner magnet surface 10b of the magnet 10, and the outer holding surface 11 of the magnet embedding hole 8C is set to have a smaller radius of curvature than the outer magnet surface 10a of the magnet 10.

[0046] When a magnet 10 is inserted into the magnet embedding hole 8C configured as described above and embedded, the apex 11d on the outer retaining surface 11 and the apex 12d on the inner retaining surface 12 of the magnet embedding hole 8C are in point contact with the outer magnet surface 10a and the inner magnet surface 10b of the magnet 10, respectively, at any cross section.

[0047] According to the above-described fourth embodiment, it is possible to obtain the same functions and effects as those of the above-described first embodiment. Furthermore, in this embodiment, the magnets 10 can be arranged along the q-axis magnetic flux lines, so that the reluctance torque can be increased.

[0048] Fig. 6 shows a rotor structure according to a fifth embodiment of the present invention. As shown in the figure, in this fifth embodiment, unlike the above-mentioned fourth embodiment, each magnet embedding hole 8D and magnet 20 are formed so as to be curved convexly toward the radially outward side (upper side in Fig. 6) opposite to the axis C.

[0049] In the magnet embedding hole 8D of this fifth embodiment, the outer retaining surface 11 (convex outer surface) and the inner retaining surface 12 (convex inner surface) are both formed in an arc shape that is convexly curved radially outward and has a predetermined radius of curvature.

[0050] On the other hand, the magnet 20 of the fifth embodiment has an outer magnet surface 20a (outer facing magnet surface) and an inner magnet surface 20b (inner facing magnet surface), both of which are convexly curved radially outward, as well as a left magnet surface 20c and a right magnet surface 20d connected to these.

[0051] Additionally, the outer magnet surface 20a and inner magnet surface 20b of the magnet 20 face the outer holding surface 11 and inner holding surface 12 of the magnet embedding hole 8D, respectively, and have a predetermined radius of curvature. Specifically, the outer holding surface 11 of the magnet embedding hole 8D is set to have a larger radius of curvature than the outer magnet surface 20a of the magnet 20, and the inner holding surface 12 of the magnet embedding hole 8D is set to have a smaller radius of curvature than the inner magnet surface 20b of the magnet 20.

[0052] When a magnet 20 is inserted into the magnet embedding hole 8D configured as described above and embedded, the apex 11e on the outer retaining surface 11 and the apex 12e on the inner retaining surface 12 of the magnet embedding hole 8D are in point contact with the outer magnet surface 20a and the inner magnet surface 20b of the magnet 20, respectively, at any cross section.

[0053] According to the fifth embodiment, it is possible to obtain the same functions and effects as those of the first embodiment. Furthermore, in this embodiment, the magnet torque of the magnet 20 can be effectively utilized.

[0054] 7 shows a rotor structure according to a sixth embodiment of the present invention. As shown in the figure, in this sixth embodiment, unlike the above-mentioned first to fifth embodiments, magnets 9 are arranged in multiple layers (two layers in this embodiment) in the radial direction.

[0055] As shown in Figure 7, the rotor 3 of this sixth embodiment has two outer magnet embedding holes 8E, 8E on the left and right, which are similar to the two left and right magnet embedding holes 8, 8 in the first embodiment, and two inner magnet embedding holes 8F, 8F on the left and right, which are arranged radially inward from the outer magnet embedding holes 8E, 8E, with one magnet 9 embedded in each outer magnet embedding hole 8E and two magnets 9, 9 embedded in each inner magnet embedding hole 8F.

[0056] Specifically, each outer magnet embedding hole 8E has an inwardly convexly curved arc-shaped outer retaining surface 11 and inner retaining surface 12, and their respective apexes 11f and 12f are in point contact with the outer magnet surface 9a and inner magnet surface 9b of the magnet 9 at any cross section.

[0057] The two left and right inner magnet embedding holes 8F, 8F are formed in a substantially V-shape so that they extend radially and the distance between them increases toward the outside in the radial direction. Each inner magnet embedding hole 8F has an outer holding surface 11 and an inner holding surface 12. Each of these outer holding surface 11 and inner holding surface 12 has two arcs that curve convexly inward, and two apexes 11g, 11g of the outer holding surface 11 and two apexes 12g, 12g of the inner holding surface 12 are in point contact with the outer magnet surface 9a and inner magnet surface 9b of the two magnets 9, 9, respectively, in an arbitrary cross section.

[0058] Furthermore, the inner magnet embedding hole 8F has a left locking portion 13L and a right locking portion 13R that protrude inward on both the left and right sides of the inner retaining surface 12, and in any cross-section, the left locking portion 13L is in point contact with the left side magnet surface 9c of the radially inner magnet 9, and the right locking portion 13R is in point contact with the right side magnet surface 9d of the radially outer magnet 9.

[0059] The two magnets 9, 9 embedded in the inner magnet embedding hole 8F are embedded in a state of contact with each other.

[0060] According to the sixth embodiment, it is possible to obtain the same actions and effects as the first embodiment. In particular, in the rotor 3 of the sixth embodiment, since the magnets 9 are arranged in multiple layers in the radial direction, it is possible to easily increase the reluctance torque of each magnetic pole of the rotor 3. Also, since two magnets 9, 9 are embedded in each inner magnet embedding hole 8F, it is possible to reduce the eddy currents generated during the rotation of the motor 1 compared to when a single magnet is used, and thus it is possible to suppress eddy current loss.

[0061] 8 shows a seventh embodiment of the present invention. As shown in the figure, in this seventh embodiment, similar to the sixth embodiment described above, magnets 9 are arranged in multiple layers (two layers in this embodiment) in the radial direction.

[0062] As shown in Figure 8, the rotor 3 of this seventh embodiment has an outer magnet embedding hole 8G and two inner magnet embedding holes 8H, 8H on the left and right sides arranged radially inward from the outer magnet embedding hole 8G, and three magnets 9, 9, 9 are embedded in each of the outer magnet embedding hole 8G and each inner magnet embedding hole 8H.

[0063] Specifically, the outer magnet embedding hole 8G is formed so as to be curved convexly inward in the radial direction as a whole. The outer magnet embedding hole 8G also has an outer holding surface 11 that is curved convexly inward in an arc shape, and three inner holding surfaces 12, 12, 12. The apex 12h of each inner holding surface 12 and the apex 11h of the opposing outer holding surface 11 are in point contact with the inner magnet surface 9b and the outer magnet surface 9a of each magnet 9, respectively, in any cross section.

[0064] Furthermore, the outer magnet embedding hole 8G has a left locking portion 13L and a right locking portion 13R that protrude inward on both the left and right sides of each inner retaining surface 12, and these left locking portion 13L and right locking portion 13R are in point contact with the left magnet surface 9c and right magnet surface 9d of the corresponding magnet 9, respectively, in any cross section.

[0065] Meanwhile, the two inner magnet embedding holes 8H, 8H on the left and right extend while curving in the radial direction and are formed into a substantially U-shape. Each inner magnet embedding hole 8H has an outer holding surface 11 that is curved inwardly and has an arc-shaped inner holding surface 12, 12, 12. The apex 12j of each inner holding surface 12 and the apex 11j of the opposing outer holding surface 11 are in point contact with the inner magnet surface 9b and the outer magnet surface 9a of each magnet 9, respectively, in any cross section.

[0066] Furthermore, the inner magnet embedding hole 8H has a left locking portion 13L and a right locking portion 13R that protrude inward on both the left and right sides of each inner retaining surface 12, and these left locking portion 13L and right locking portion 13R are in point contact with the left magnet surface 9c and right magnet surface 9d of the corresponding magnet 9, respectively, in any cross section.

[0067] According to the seventh embodiment, it is possible to obtain the same actions and effects as the first and sixth embodiments. In particular, in the rotor 3 of the seventh embodiment, three magnets 9 are embedded in both the outer magnet embedding hole 8G and the inner magnet embedding hole 8H, so that the eddy current generated during the rotation of the motor 1 can be further reduced compared to when only one magnet is used, and thus the eddy current loss can be further suppressed. Also, in this embodiment, like the arc-shaped magnets 10 and 20 of the fourth and fifth embodiments, the magnets 9 can be arranged along the q-axis magnetic flux line, so that the reluctance torque and efficiency can be improved more easily compared to when they are arranged in a V-shape.

[0068] The present invention is not limited to the above-described embodiment, but can be embodied in various forms. For example, in the above-described embodiment, the magnet 9 having a rectangular cross section and the magnets 10 and 20 having an arc-shaped cross section are exemplified, but the magnets in the rotor structure of the present invention are not limited to the above-described shapes, and magnets having various shapes can be used, such as a kamaboko shape in which one side is flat and the other is arc-shaped, or a shape in which the radius of curvature of the outer and inner arc-shaped magnet surfaces and the center of the arc are different from each other (for example, a crescent shape).

[0069] Furthermore, the detailed configurations of the rotor 3, rotor core 7, magnet embedding holes 8, 8A-8H, and magnets 9, 10, 20 shown in the embodiment, such as their shapes, sizes, and numbers, are merely examples and can be changed as appropriate within the spirit of the present invention. [Explanation of symbols]

[0070] 1. Motor (electric motor) 2 Shaft (rotating axis) 3 Rotor 7 Rotor core 8 Magnet embedding hole of the first embodiment 8A Magnet embedding hole of the second embodiment 8B Magnet embedding hole of the third embodiment 8C Magnet embedding hole of the fourth embodiment 8D Magnet embedding hole of the fifth embodiment 8E Sixth embodiment of outer magnet embedding hole 8F Inner magnet embedding hole of the sixth embodiment 8G Seventh embodiment outer magnet embedding hole 8H Inner magnet embedding hole of the seventh embodiment 9 Permanent magnets (magnets) 9a Outer magnet surface 9b Inner magnet surface 9c Left side magnet surface 9d Right side magnet surface 10 Magnet of the fourth embodiment 10a Outer magnet surface (inner opposing magnet surface) 10b Inner magnet surface (outer facing magnet surface) 10c Left side magnet surface 10d Right side magnet surface 11 Outer holding surface (first holding surface, convex inner surface, convex outer surface) 11a to 11j: Top of outer holding surface (first contact portion) 12 Inner holding surface (second holding surface, convex outer surface, convex inner surface) 12a to 12j Top of inner retaining surface (second contact portion) 13L Left locking part 13R Right locking part 20 Magnet of the fifth embodiment 20a Outer magnet surface (outer opposing magnet surface) 20b Inner magnet surface (inner opposing magnet surface) 20c Left magnet surface 20d Right magnet surface C-axis

Claims

1. A rotor structure of an electric motor having a rotor through which a rotating shaft passes and which is fixed to the rotating shaft, a rotor core having a plurality of magnet embedding holes extending along an axis passing through the center of the rotating shaft; A plurality of magnets embedded in the plurality of magnet embedding holes, respectively; Equipped with each of the plurality of magnet embedding holes has a first holding surface and a second holding surface that face each other with the embedded magnet therebetween and hold the magnet in a sandwiched state; a rotor structure for an electric motor, characterized in that the first retaining surface and the second retaining surface are in point contact with the held magnet at any cross section perpendicular to the axis, and have first abutment portions and second abutment portions respectively formed so as to be continuous along the axis.

2. The first contact portion is composed of one or a plurality of first contact portions, 2. The rotor structure of the electric motor according to claim 1, wherein the second contact portion is composed of one or a plurality of second contact portions.

3. The first retaining surface and the second retaining surface are formed in an arc shape that is convexly curved toward one of a radially inner side that is the axis side and a radially outer side that is the opposite side to the axis in the arbitrary cross section, and are configured as a convex outer surface located on the outer side of the convex direction and a convex inner surface located on the inner side of the convex direction, the magnet is formed in an arc shape that is convexly curved toward one side in the arbitrary cross section as a whole, and has an outer opposing magnet surface facing the convex outer surface and an inner opposing magnet surface facing the convex inner surface, The convex outer surface has a radius of curvature larger than that of the outer opposing magnet surface, so that a top portion of the convex outer surface functions as a single first abutment portion, 2. The rotor structure of the electric motor according to claim 1, wherein the convex inner surface has a radius of curvature set smaller than that of the inner opposing magnet surface, so that a top of the convex inner surface functions as a single second abutment portion.

4. 2. The rotor structure of an electric motor as described in claim 1, characterized in that each of the multiple magnet embedding holes further has two engaging portions that make point contact at the arbitrary cross section and are formed continuously along the axis so as to sandwich the magnet from both sides in a direction approximately perpendicular to the direction in which the magnet is sandwiched by the first retaining surface and the second retaining surface.

5. The plurality of magnet embedding holes are arranged in groups of two or more magnet embedding holes, the groups being arranged at predetermined angles around the axis, 2. The rotor structure of an electric motor according to claim 1, wherein the magnet embedding holes of each set are arranged in a circumferential direction about the axis and / or in a radial direction of the axis.

6. 6. The rotor structure for an electric motor according to claim 1, wherein one or a plurality of magnets are embedded in each of the plurality of magnet embedding holes.

Images