Rotating electric machine

Abstract

The purpose of the present invention is to reduce the weight of a rotor of a rotating electrical machine, reduce the amount of rotor deformation during high-speed rotation, and reduce the q-axis reluctance. Magnet insertion holes (126a-126c) of a rotor are symmetrically positioned at a plurality of positions about a d axis, which is a magnetic pole center axis, and lightening holes (128, 129) configured so as to include a curved line are formed on the inner peripheral side of the magnet insertion holes (126a, 126c) close to a q axis. The cross-sectional shapes of the lightening holes (128, 129) are arranged such that the closest point (70) from the rotation axis (A1) is a curved portion having the largest curvature. The magnet insertion holes (126a, 126c) are located at positions separated by a certain distance S from all regions of the portions of the linear portions of the lightening holes, and the outermost peripheral position (50) of the sides constituting the lightening holes is located on the outer peripheral side compared with the end portion (60) of the sides constituting the magnet insertion holes, the end portion being closest to the central axis of the rotor.

Description

Technical Field

[0001] The present invention relates to a rotating electric machine, and more particularly to a radial gap type rotating electric machine having a rotor in which a permanent magnet is embedded. Background Art

[0002] A permanent magnet type rotating electric machine in which a permanent magnet is embedded in the rotor of the rotating electric machine is known. The structure of the rotor of the rotating electric machine is that a space for inserting a magnet is provided in an iron core formed by laminating electromagnetic steel sheets of a predetermined design shape, and a permanent magnet is inserted into the space. As a prior art regarding a method for fixing a permanent magnet, there is, for example, Patent Document 1. Patent Document 1 discloses a rotor of an inner rotor type rotating electric machine including a rotor core having a cylindrical outer peripheral surface of an iron core, and a plurality of permanent magnets embedded inside the rotor core, the rotor including an inter-pole bridge portion extending from the outer periphery of the iron core to the radial inner side of the iron core between two permanent magnets adjacent in the circumferential direction of the iron core between the rotor magnetic poles, and an inter-pole gap portion formed on the radial inner side of the iron core of the inter-pole bridge portion between the rotor magnetic poles. The inter-pole gap portion has a parallel wall surface formed in parallel with the radial inner side surface of the iron core of each permanent magnet on both sides of the inter-pole bridge portion, and an inner bridge portion formed between the radial inner side surface of the iron core and the parallel wall surface is connected to the radial inner end of the iron core of the inter-pole bridge portion. The permanent magnet has a shape in which the length in a direction parallel to the extension direction of the inner side surface of the core radial direction is longer than the width in a direction perpendicular to the extension direction. With such a structure, the problem of increasing the magnetic resistance of the q-axis while suppressing a decrease in strength can be solved.

[0003] As another prior art related to the method of fixing permanent magnets, there is Patent Document 2. The rotor described in Patent Document 2 includes a rotor core having a plurality of openings formed along the circumferential direction, a plurality of permanent magnets respectively inserted into the respective openings to form magnetic poles, and a filler respectively pressurized and filled in the gap between the inner circumferential surface of each opening and the outer circumferential surface of each permanent magnet, and the rotor core is configured to further have a hole portion arranged along the circumferential direction of the rotor core and configured to absorb the deformation of the rotor core in the circumferential direction outside. With such a structure, the problem of suppressing the deformation of the rotor core can be solved.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2012-75278

[0007] Patent Document 2: Japanese Patent Application Publication No. 2007-89291 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In order to achieve energy saving due to improved efficiency and reduce CO2 emissions, rotating electrical machines require high-speed drives for compactness and high power. The motor generates a large reverse electromotive force in proportion to the high-speed rotation, so weak magnetic field control is often performed to suppress the reverse electromotive force in accordance with the voltage limit of the inverter driving the motor. At this time, in an embedded magnet type motor, the magnet torque is reduced due to weak magnetic field, but the reluctance torque using magnetic saliency as electromagnetic force can be used at the same time. The magnitude of the reluctance torque depends on the phase and magnetic saliency of the armature current, so it is important to increase the difference between the d-axis magnetic flux and the q-axis magnetic flux by ensuring the magnetic path of the q-axis magnetic flux.

[0010] Because a large centrifugal force acts on the rotor of the motor during high-speed rotation, a safety design is required to prevent damage caused by plastic deformation of the rotor core or protrusion of the magnets inserted into the rotor core as a problem during high-speed rotation. On the other hand, in order to maintain the torque during high-speed rotation, it is necessary to apply reluctance torque, and for this purpose, it is necessary to fully ensure the path of the q-axis magnetic flux of the rotor. As a countermeasure, in the structures described in Patent Documents 1 and 2, a gap portion is provided between the magnetic poles of the rotor core (on the q-axis) in order to alleviate the stress concentration occurring in the magnet receiving portion. However, although the effect of reducing the stress applied to the magnet receiving portion can be obtained by hollowing out the rotor core, on the other hand, there is a risk of stress concentration at the hollowed-out hole and fracture at the stress concentration location. In addition, the weight-reducing hole is located in the magnetic path of the q-axis magnetic flux, so there is a risk of other problems such as it becoming a reluctance and deteriorating the performance of the motor.

[0011] The present invention has been developed in view of the above background, and an object of the present invention is to provide a radial gap type rotating electrical machine having an embedded magnet type rotor with reduced rotor deformation during high-speed rotation and small q-axis magnetic resistance.

[0012] Another object of the present invention is to provide a rotating electric machine that prevents stress from concentrating on the lightening holes themselves when lightening holes are formed continuously in the rotation axis direction in a rotor core, thereby preventing the lightening holes from becoming magnetic resistance of q-axis magnetic flux and deteriorating motor performance.

[0013] Technical solutions to solve problems

[0014] Representative features of the invention disclosed in the present application are described as follows. According to one feature of the present invention, a rotating electric machine includes a stator having a stator coil, and a rotor having a magnet insertion hole into which a permanent magnet constituting a magnetic pole can be inserted and maintained on the inner side of the stator so as to be rotatable around a rotating shaft. A plurality of magnet insertion holes are linearly symmetrically arranged around the magnetic pole center axis, i.e., the d-axis, as the center. In addition, in each magnetic pole of the rotor, a weight-reducing hole is formed near the inner circumference (the side close to the rotating shaft) of the permanent magnet located at a position separated from the q-axis. The weight-reducing hole can be semicircular or teardrop-shaped. The contour constituting the weight-reducing hole is formed to include a curve, and the position closest to the weight-reducing hole from the rotating shaft is composed of a curve with the largest curvature.

[0015] According to another feature of the present invention, the rotor core is formed by electromagnetic steel sheets stacked in the direction of the rotation axis, and in each magnetic pole of the rotor core, a permanent magnet is arranged on the magnetic pole center axis, i.e., the d-axis, and the remaining permanent magnets are arranged in the magnetic pole in a manner symmetrical (plane symmetrical) with respect to the d-axis. Two weight-reducing holes are provided in the magnetic pole, which are arranged at a slight distance from the inner circumference side (the side close to the rotation axis) of the permanent magnet closest to the q-axis. The permanent magnets used are permanent magnets whose circumferential width is larger than the radial thickness. In addition, except for the permanent magnets located on the d-axis, the permanent magnets are arranged in an inclined manner in which the direction of the circumferential center line of the permanent magnet has a predetermined angle θ with the tangent direction of the rotor core. The inclination direction is such that the side of the permanent magnet close to the p-axis is located radially outward. The relative parts of the sides of the magnet insertion hole and the inner circumference side of the weight-reducing hole are located at a position where a certain distance is maintained, and the outermost peripheral position of the weight-reducing hole is located on the outer peripheral side compared to the end of the side constituting the magnet insertion hole that is closest to the central axis of the rotor.

[0016] Effects of the Invention

[0017] According to the present invention, a radial gap type rotating electric machine having an embedded magnet type rotor that reduces the weight of the rotor core and the amount of rotor deformation during high-speed rotation can be provided. In addition, a rotating electric machine that can reduce magnetic resistance and maintain high-efficiency motor performance can be provided because no weight-reducing holes are formed on the q-axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram showing the structure of a rotating electrical machine 1 according to a first embodiment of the present invention.

[0019] Figure 2 yes Figure 1 Cross-sectional view at section AA.

[0020] Figure 3 yes Figure 2 A partial enlarged view of the rotor 20.

[0021] Figure 4It is a cross-sectional view of a rotary electric machine 1A according to a second embodiment of the present invention.

[0022] Figure 5 yes Figure 4 A partial enlarged view of the rotor 20A.

[0023] Figure 6 is a cross-sectional view of a rotary electric machine 1B according to a third embodiment of the present invention.

[0024] Figure 7 yes Figure 6 A partial enlarged view of the rotor 20B. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In the following drawings, the same reference numerals are assigned to the same parts, and repeated descriptions are omitted.

[0026] Example 1

[0027] exist Figure 1 Detailed Description of the Invention The structure of a rotating electrical machine (motor) according to a first embodiment of the present invention is shown in FIG. Figure 1 : is a cross-sectional view on a vertical plane passing through the rotation axis A1 of the rotating electrical machine 1. The rotating electrical machine 1 is a distributed winding inner rotor type permanent magnet synchronous motor having 48 slots and 8 poles. The number of slots and the number of poles are not particularly limited in the present invention, and for example, a motor having 24 slots and 2 magnetic pole pairs, or a motor having other numbers of slots and poles may also be used.

[0028] like Figure 1 As shown, the rotating electric machine 1 is constructed to include a stator 10, a rotor 20 rotatably supported on the radial inner side of the stator 10, a housing 2 covering the stator 10, and a rotating shaft 4 fixed in the rotor 20. In the present embodiment, the housing 2 is made of a non-magnetic metal such as an aluminum alloy, and is formed to cover the stator 10 as a whole. The illustration shows a portion of the rotating shaft 4 formed to extend to the outside of one side of the housing 2 in order to be used as an output shaft. The cylindrical rotor core 120 is radially opposite to the inner circumferential surface of the stator 10 on the inner side of the cylindrical stator 10 with a small gap 102 therebetween. The stator 10 has a plurality of slots (see FIG. 1 ) evenly spaced in the circumferential direction (rotational direction). Figure 2 ) has an armature winding 112 wound in the slots across a certain slot interval.

[0029] The rotor 20 is configured to include a rotor core 120 formed by stacking a plurality of relatively thin electromagnetic steel sheets in the direction of the rotation axis A1, and a permanent magnet 122 fixedly embedded in a magnet insertion hole 126 that penetrates the interior of the rotor core 120 in the direction of the rotation axis A1. The cross-sectional shape of the permanent magnet 122 orthogonal to the rotation axis A1 is Figure 2The rectangle described later is a shape that is elongated in the direction of the rotation axis A1. Figure 1 The permanent magnet 122 appears to be continuous in the direction of the rotation axis A1, but it can also be formed in a divided manner so that a plurality of divided permanent magnets 122 are arranged in the direction of the rotation axis A1. Lightening holes 128 and 129 are formed in the rotor core 120 on the side closer to the rotation axis 4 than the permanent magnet 122 and extending through the rotor core in the axial direction.

[0030] When the two ends of the lightening holes 128 and 129 in the direction of the rotation axis A1 are provided with a fixing plate (not shown) that prevents the permanent magnet from moving in the direction of the rotation axis A1, the openings of the lightening holes 128 and 129 can be closed, or can be configured to remain open and allow air circulation. The lightening holes 128 and 129 are formed to reduce the deformation of the magnet insertion hole 126 during high-speed rotation by achieving lightweight, thereby preventing the increase of the magnetic resistance of the q axis. In addition, the lightening holes 128 and 129 can also have other uses. For example, a structure can be adopted in which a cooling medium (coolant), coolant, insulating oil, etc. flows from an opening at one end of the rotation axis A1 of the rotating rotor core 120. In the case where liquid flows in the lightening holes 128 and 129, a structure in which pressure is applied by a pump or the like to cause the liquid to flow can be adopted. Alternatively, the structure may be such that the liquid droplets are splashed toward the openings of the lightening holes 128 and 129 , the liquid is moved inside the lightening holes 128 and 129 by the rotational force of the rotor 20 , and the liquid droplets are discharged from the other opening.

[0031] Figure 2 yes Figure 1 The cross-sectional view at the AA section shows Figure 1 The structure inside the shell 2. Figure 2 In the embodiment, the rotor 20 is fixed to the rotating shaft 4 and rotates with the rotating shaft 4 about the rotating shaft A1. In the following description, unless otherwise stated, the words "inner circumference" and "outer circumference" refer to the side closer to the rotating shaft A1 and the side farther from the rotating shaft A1, respectively. In addition, the word "radial direction" refers to the direction of a straight line intersecting the rotating shaft at right angles, and the word "circumferential direction" refers to the direction of a straight line intersecting the rotating shaft at right angles. Figure 2 The arrow in the figure shows the rotation direction of the rotor 20. The rotation direction of the rotor is, for example, Figure 2 The direction of the arrow can also be used to rotate it in the opposite direction of the arrow.

[0032] The rotor 20 is composed of a rotating shaft 4, a ring-shaped rotor core 120 made of a magnetic body, and a permanent magnet 122 embedded in the inner side of a magnet insertion hole 126. By inserting and fixing the rotating shaft 4 in the rotor core 120, the rotor core 120 rotates synchronously with the rotating shaft 4. The rotor core 120 is composed of a processed magnetic body. For example, it is composed of stacked steel plates formed into a magnetic body of any shape by press working or laser working. As for the material of the magnetic body, a thin silicon steel plate is generally used, but the present invention is not limited to this.

[0033] A plurality of magnet insertion holes 126 and a plurality of weight-reducing holes 128 and 129 are formed inside the rotor core 120. In the rotating electrical machine 1 of this embodiment, the number of magnetic poles is 8, and three permanent magnets 122 ( Figure 3 122a, 122b, 122c shown). Therefore, the magnet insertion holes 126 are arranged in the circumferential direction, 3 × 8 poles = 24 per pole. Each permanent magnet 122 is arranged in one magnet insertion hole 126 formed independently, so a total of 24 magnet insertion holes 126 are also arranged. In addition, in the present embodiment, three permanent magnets 122 are arranged in one magnetic pole, but the number of magnetic poles is arbitrary, and the present invention can be applied to a rotating motor in which the number of magnets constituting one magnetic pole is set to more than 2. When the number of permanent magnets 122 arranged in the magnetic pole is an odd number, at least one is arranged on the d-axis and the rest are arranged so as not to overlap with the d-axis. When the number of permanent magnets 122 arranged in the magnetic pole is an even number, all permanent magnets 122 are arranged so as not to overlap with the d-axis.

[0034] The plurality of (here 3) permanent magnets 122 constituting one magnetic pole are arranged symmetrically with the magnetic center axis of the magnetic pole, i.e., the d-axis, as the center line. The permanent magnets 122 are arranged in the rotor core 120 in the direction of the magnetic pole in a manner that each pole is alternated in the circumferential direction. In this embodiment, four magnetic pole pairs are formed. The material of the permanent magnet 122 can be any one of a ferrite magnet system, a neodymium magnet system, a samarium cobalt magnet system, etc. In addition, the permanent magnet 122 has the same or substantially the same length as the rotor core 120 in the axial direction, and the length can be divided into a plurality of parts, or divided not only in the length direction but also in the radial or circumferential direction. When the number of magnets constituting one magnetic pole is an odd number, one of the magnets is arranged in the center across the d-axis. The magnet insertion hole 126 is a rod-shaped shape having a substantially rectangular cross-sectional shape, and the length direction of the rod-shaped shape extends in a direction parallel to the rotation axis A1. The magnet insertion hole 126 also has the same cross-sectional shape corresponding to the configuration of the permanent magnet 122, and is formed to extend in a direction parallel to the rotation axis A1.

[0035] The stator 10 is composed of a stator yoke 110 that is roughly cylindrical, a plurality of teeth 116 that protrude radially inward from the outer cylindrical portion of the stator yoke 110, and an armature winding 112. There are 48 teeth 116 arranged at equal intervals in the circumferential direction. The space on the outer peripheral side of the gap 102 and surrounded by two teeth 116 is a slot 104, and the armature winding 112 is accommodated in the slot 104. There are 48 slots 104 in total. The armature winding 112 is composed of a flat wire with a roughly rectangular cross-section, but this shape is not necessary, and it can also be composed of a round wire with a circular cross-section, or a stranded wire formed by bundling thin wires. In addition, the armature winding 112 can also be fixed in the slot 104 with an insulator. The armature winding 112 uses, for example, a copper wire formed by coating an insulating film (such as varnish or engineering plastic) on a conductor mainly composed of copper. If insulation protection is provided by inserting a copper wire into a bobbin made of an insulator, a bare wire without an insulating film may also be used. The front end of the tooth facing the gap is formed into a rectangular shape so that the cross section of the slot 104 becomes approximately rectangular. However, the shape of the slot 104 in the present invention is not limited thereto. For example, a substantially elliptical flange extending in two directions in the circumferential direction may also be formed at the front end of the tooth.

[0036] Figure 3 (A) is correct Figure 2 The rotor 20 shown is a partial enlarged view of only two poles. Figure 3 (B) is a partial enlarged view of the outer peripheral portion of one of the poles. The magnetic pole of one pole of the stator 10 is composed of a first magnet insertion hole 126a, a second magnet insertion hole 126b, a third magnet insertion hole 126c provided in the rotor core 120, and a first permanent magnet 122a, a second permanent magnet 122b, a third permanent magnet 122c embedded in each magnet insertion hole, and two weight reduction holes 128 and 129. Other holes such as holes for positioning during assembly can be formed near the rotation axis of the rotor core 120, which are not shown here. Figure 3 In (A), arrows indicating the magnetization directions of the permanent magnets are respectively marked on the first to third permanent magnets 122a, 122b, and 122c. Figure 3 In (A), the outer circumference of the permanent magnets 122a to 122c in the magnetic pole on one side of the d-axis is shown as an S pole, and the inner circumference is an N pole. On the other hand, the outer circumference of the permanent magnets 122a to 122c in the magnetic pole on one side of the d-axis, which is not shown in the figure, and which are shown as black arrows pointing radially outward, is an N pole, and the inner circumference is an S pole.

[0037] The second permanent magnet 122b is arranged in such a manner that the center of the magnetization direction overlaps with the d-axis, with the magnetic center axis of one magnetic pole being the d-axis. The magnet insertion holes 126a, 126b, and 126c into which each permanent magnet is inserted are formed in accordance with the arrangement direction of the arranged permanent magnets 122a to 122c. In addition, the first permanent magnet 122a and the third permanent magnet 122c are arranged in a state of being tilted at a predetermined angle θ relative to the tangential direction of the rotation plane. That is, the permanent magnet 122b arranged at a position overlapping with the d-axis is arranged in such a manner that the angle formed by its radial center line and the d-axis is 90 degrees, and the angle formed by the radial center lines 124a and 124c of the permanent magnets 122a and 122c arranged at a position not overlapping with the d-axis and the d-axis is an inclination angle less than 90 degrees by θ. The inclination directions of the permanent magnets 122a and 122c are opposite, and they are arranged so that they are symmetrical with respect to the d-axis.

[0038] like Figure 3 As shown in (B), the cross-sectional shape of the lightening hole 128 is semicircular, and is a shape in which a straight portion 128a and an arc portion 128b are combined. The semicircular straight portion 128a is arranged on the outer circumference and the arc portion 128b is arranged on the inner circumference, and the internal space of the semicircle is a hollow portion where no magnetic pole is formed. Similarly, the cross-sectional shape of the lightening hole 129 is semicircular, and is a shape in which a straight portion 129a and an arc portion 129b are combined. Regarding the cross-sectional shape, the cross-section at any position on the rotation axis A1 is a hollow of the same shape, and passes through the rotor core 120 in a continuous manner from one side to the other side in the direction of the rotation axis of the rotor core. Two lightening holes 128 and 129 are arranged for each magnetic pole, and one lightening hole 128 is arranged on the inner circumference of the first magnet insertion hole 126a, and one lightening hole 129 is arranged on the inner circumference of the third magnet insertion hole 126c.

[0039] The weight-reducing hole 128 is provided at a position opposite to the inner long side of the first permanent magnet 122a having a rectangular cross-sectional shape, and is provided so that the range occupied by the first permanent magnet 122a is projected inwardly from the long side portion in the orthogonal direction (enclosed by the dot-dash line obtained by extending the short side) Figure 3 The lightening hole 129 is provided in the projection range P1 shown in (A) on the inner side of the third permanent magnet 122c having a rectangular cross-sectional shape (enclosed by the dotted line obtained by extending the short side). Figure 3within the range of the projection range P3 shown in (A). The straight portions 128a and 129a of the outer edges of the respective weight reduction holes 128 and 129, which are opposite to the straight portions 123a and 123c of the first magnet insertion hole 126a and the third magnet insertion hole 126c, are parallel to the straight portions 123a and 123c on the inner peripheral side of the first magnet insertion hole 126a and the third magnet insertion hole 126c, and are separated by a certain distance S. That is, the widths of the two parallel straight portions 123a and 128a, and 123c and 129a are S respectively, and are formed in a positional relationship where the width S is smaller than the length of the parallel portion, that is, the length of the straight portions 128a and 129a. Each of the weight reduction holes 128 and 129 is arranged at a position that does not overlap with the central axis of the magnetic pole, that is, the d-axis, and is arranged at a position separated from the d-axis and the q-axis so as not to overlap with the boundary line of the adjacent pole, that is, the q-axis.

[0040] The interiors of the weight reduction holes 128 and 129 are hollow and can be used as passages for allowing a coolant (such as air, coolant, or oil) transported from the outside by a pump or the like to flow inside. The imaginary circle 83 shown by the dashed line connecting the outermost peripheral points 50 of the weight reduction holes 128 and 129 is located on the outer peripheral side compared to the imaginary circle 82 shown by the dashed line connecting the ends (the positions indicated by the arrows 60) of the first magnet insertion hole 126a to the third magnet insertion hole 126c close to the central axis A1. That is, the relationship between the distance B from the center of the rotation axis of the imaginary circle 83 connecting the outermost peripheral points 50 of the weight reduction holes 128 and 129, and the distance A from the center of the rotation axis of the imaginary circle 82 connecting the innermost peripheral side ends 60 of the magnet insertion holes 126a to 126c is set such that A < B always.

[0041] The distance from the central axis A1 of the imaginary circle 81 shown by the dashed line connecting the points 70 with the closest distance from the center of the rotation axis among the outer edges constituting the weight reduction holes 128 and 129 is C. The distance C is located in the innermost peripheral portion of the weight reduction holes 128 and 129, and the distance relationship is always C < A < B. This innermost peripheral portion 70 is located on the curve of the semicircle constituting the weight reduction hole 128, and this curve is the portion with the largest curvature among the curves constituting the weight reduction holes 128 and 129. By adopting the rotor core 120 with such a shape, the vicinity of the first magnet insertion hole 126a can be lightened through the weight reduction hole 128, and the vicinity of the third magnet insertion hole 126c can be lightened. Furthermore, when driving the rotating electric machine 1, the weight reduction holes 128 and 129 do not become a magnetic resistance that obstructs the q-axis magnetic flux generated in the armature. As a result, the magnetic salient polarity of the rotating electric machine increases, and the applicable reluctance torque increases. Moreover, when the rotor 20 rotates, centrifugal force acts on the ends 60 of each magnet insertion hole, and tensile stress is generated on both sides across the ends 60 of the magnet insertion hole, but due to the lightening of the rotor core 120, the tensile stress decreases, and stress concentration can be alleviated.

[0042] When the rotor 20 rotates, the tensile stress caused by the centrifugal force acts on the parallel portion between the straight portions of the magnet insertion holes 126a and 126c and the straight portions 128a and 129a of the weight reduction holes 128 and 129. However, since no narrow portion or uneven portion is formed in the parallel portion, it is a structure in which stress concentration is not likely to occur. In addition, on the inner peripheral side of the weight reduction holes 128 and 129, the innermost peripheral point 70 is located in the curved portion (curved surface portion), so the stress is dispersed. Therefore, it is a structure in which stress concentration is not likely to occur, and deformation or fracture of the weight reduction holes can be prevented. In addition, regarding the stress concentration at the corners of the magnet insertion holes 126a to 126c located on the imaginary circle 82, since most of the weight reduction holes 128 and 129 are located on the outer peripheral side compared to the corners of the magnet insertion holes 126a to 126c located on the imaginary circle 81, it is more greatly alleviated. This is because the centrifugal force acts on the outer peripheral side of the stress concentration point. This effect is obtained by making the relationship between the distances (radii A and B) from the rotation axis A1 of the imaginary circle 82 and the imaginary circle 83 always A < B. However, when the distance (distance S of the parallel portion) between the weight reduction hole 128 and the magnet insertion hole 126a and between the weight reduction hole 129 and the magnet insertion hole 126c is too small, the magnet flux from the permanent magnets 122a to 122c is obstructed, and the stress in the parallel portion increases. Therefore, it is important to appropriately design the distance A according to the rotational speed of the rotating electric machine and the shape of the magnets.

[0043] As described above, according to the present embodiment, not only can the damage of the rotating electric machine 1 due to the centrifugal force acting on the rotor during high-speed rotation be prevented, but also the reluctance torque during field weakening increases, and a rotating electric machine with higher efficiency can be configured.

[0044] Embodiment 2

[0045] Next, use Figure 4 and Figure 5 to describe the second embodiment of the present invention. Figure 4 is a cross-sectional view of the rotating electric machine 1A according to the second embodiment of the present invention. Figure 4 The structure of the stator 10 of the rotating electric machine 1A shown is exactly the same as that of the stator 10 of the rotating electric machine 1 according to the first embodiment shown in Figure 2 Only a part of the structure of the rotor 20A is different from that of the rotor 20 shown in Figure 2 The different structure is the portion corresponding to the weight reduction holes 128 and 129 of Figure 2 . In the second embodiment, the cross-sectional shape in the direction of the rotation axis A1 of the weight reduction holes 228 and 229 is not a semicircle but a teardrop shape. The idea of providing two weight reduction holes 228 and 229 in each pole and disposing them near the inner peripheral sides of the permanent magnets 122a and 122c respectively is the same as that of the first embodiment. In addition, the shapes and arrangements of the magnet insertion holes 126a to 126c and the shapes and inclined directions of the permanent magnets 122a to 122c inserted therein are the same as those in Figure 2 is the same as that of the first embodiment shown.

[0046] Figure 5 (A) of is an enlarged view of two poles of the rotor 20A in the second embodiment of the present invention. Three permanent magnets 122a to 122c are respectively provided circumferentially within one magnetic pole. The permanent magnets 122a to 122c are respectively housed in the first magnet insertion hole 126a, the second magnet insertion hole 126b, and the third magnet insertion hole 126c. The weight reduction holes 228 and 229 are arranged on the inner peripheral side of the magnet insertion hole 126a and the inner peripheral side of the magnet insertion hole 126c, respectively, in the same manner as in the first embodiment. The weight reduction holes 228 and 229 are formed as through holes of the rotor core 220, similar to the weight reduction holes 128 and 129. The rotor 20A has a rotor core 220 with 8 poles, and the shapes and arrangements of the permanent magnets 122a to 122c within each pole are the same as those in the first embodiment. That is, as Figure 5 shown in (A) of, when viewed in a cross-section orthogonal to the rotation axis A1, the shape of the rotor core 220 is a shape that is rotationally symmetric about the rotation axis A1 in the rotation direction and is line-symmetric with respect to any d-axis.

[0047] The imaginary circle 283 shown by the dashed line connecting the outermost peripheral points 250 of the weight reduction holes 228 and 229 is located on the outer peripheral side compared to the imaginary circle 282 shown by the dashed line connecting the ends (the positions indicated by the arrows 260) of the first magnet insertion hole 226a to the third magnet insertion hole 226c close to the central axis A1. That is, the relationship between the distance B from the rotation axis center of the imaginary circle 283 connecting the outermost peripheral points 250 of the weight reduction holes 228 and 229 and the distance A from the rotation axis center of the imaginary circle 282 connecting the innermost peripheral side positions 260 of the magnet insertion holes 226a to 226c is always set as A < B.

[0048] The distance from the central axis A1 of the imaginary circle 281 shown by the dashed line connecting the points 270 with the shortest distance from the rotation axis center among the outer edges constituting the weight reduction holes 228 and 229 is C. The distance C is located in the innermost peripheral part of the weight reduction holes 228 and 229, and the distance relationship is always C < A < B. This innermost peripheral part 270 is located on the curve of the semi-circle constituting the weight reduction hole 228, and this curve is the part with the largest curvature among the curves constituting the weight reduction holes 228 and 229.

[0049] The shape of the weight reduction hole 228 is as Figure 5The so-called teardrop shape shown in (B) is composed of two straight portions 228a, 228b and two curved portions 228c, 228d connecting the ends thereof. As in the first embodiment, one straight portion (straight portion 228a) constituting the lightening hole 228 is located on the outer peripheral side and is parallel to the straight portion (portion indicated by arrow 130a) on the inner side of the magnet insertion hole 126a. The distance between the straight portions 228a and 130a is S. The other straight portion (straight portion 228b) is located on the inner peripheral side. The straight portions 228a and 228b are not parallel, and the interval between the straight portions 228a and 228b becomes narrower as they approach the curved portion 228d having a smaller radius of curvature. On the contrary, the interval between the straight portions 228a and 228b becomes wider as they approach the curved portion 228c having a larger radius of curvature. The ends of the straight portions 228a and 228b constituting the lightening hole 228 (the portions intersecting with the dotted line) are connected to the curved portion 228c at the ends facing each other at a distance, and are connected to the curved portion 228d at the ends facing each other at a closer distance. Figure 5 As is apparent from (A), the shape of the lightening hole 229 is the same as that of the lightening hole 228, and the lightening hole 228 and the lightening hole 229 in the same pole are symmetrical with respect to the d axis (plane symmetric in three dimensions). One straight line portion (straight line portion 229a) constituting the lightening hole 229 is located on the outer circumference side, and is spaced apart from and parallel to the straight line portion (the portion indicated by arrow 131a) on the inner side of the magnet insertion hole 126c by a distance S. The other straight line portion (straight line portion 229b) is located on the inner circumference side.

[0050] Generally speaking, the rotor core of a rotating electric machine is formed by laminating a core of a relatively thin electromagnetic steel sheet that has been subjected to press processing in order to prevent iron loss caused by a rotating magnetic field. At this time, if there is an acute angle in the shape of the hole subjected to press processing, excessive stress is applied during processing, cracks or deformation occur, and this causes failure of press processing. Therefore, it is advantageous that the shape of the hole manufactured by press processing is formed by a simple curved shape. In the first embodiment, the side forming the weight-reducing holes 128 and 129 is a semicircular shape consisting of a curved portion and a straight portion. Therefore, the part where there is an acute angle at the connection between the curved portion and the straight portion of the weight-reducing holes 128 and 129 is a shape that is difficult to be press processed. In contrast, in the second embodiment, by forming the weight-reducing holes 228 and 229 with a shape without an acute angle, not only can the same effect as the first embodiment be obtained, but also cracks are not easily generated during press processing, and it is a shape with high production efficiency, which can achieve the effect of improving the yield rate of rotor parts.

[0051] Example 3

[0052] Figure 6It is an enlarged view of two poles of the rotor 20B in the third embodiment of the present invention. Its structure is the same as that of the first embodiment and 2 except for the parts specially stated. The configuration of the three permanent magnets 122a~122c in each pole of the rotor core 320 is the same as that of the first and second embodiments. In addition, the shape and configuration of the two weight reduction holes 228 and 229 provided in each pole are the same as those of the second embodiment. However, in the rotor core 320 of the third embodiment, the shapes of the magnet insertion hole 326 for holding the permanent magnet 122a and the magnet insertion hole 328 for holding the permanent magnet 122c are different from the first magnet insertion hole 126a and the third magnet insertion hole 126c. The shape of the magnet insertion hole 327 for holding the second permanent magnet 122b is the same as that of the second embodiment. Figure 3 The magnet insertion holes 126b shown are the same.

[0053] In the third embodiment, three gaps extending away from the permanent magnets 122 and 126 in a protruding shape are formed near the corners of the magnet insertion holes 326 and 328 that do not overlap the d-axis among the three magnet insertion holes 326 to 328. That is, a protruding gap 336 is formed from the inner corner of the rectangular space on the side close to the d-axis in the magnet insertion hole 326. In addition, two gap portions are formed from the outer corner on the side close to the q-axis, namely, a protruding gap 346 extending in the circumferential direction toward the direction close to the d-axis and a protruding gap 356 extending in the circumferential direction toward the direction close to the q-axis.

[0054] Similarly, a protruding gap 338 is formed from the inner corner of the rectangular space on the side close to the d-axis in the magnet insertion hole 328. In addition, a protruding gap 348 extending in the circumferential direction toward the direction close to the d-axis and a protruding gap 358 extending in the circumferential direction toward the direction close to the q-axis are formed from the outer corner on the side close to the q-axis.

[0055] Figure 7 (A) is related to Figure 6Compared with the figure of FIG. 1 , the partial enlarged view of the state in which the permanent magnets 122a to 122b are removed. In the third embodiment, in order to reduce the stress on the inner diameter side of the rotor core 320, the lightening holes 228 and 229 are arranged on the inner peripheral side of the first magnet insertion hole 326 and the third magnet insertion hole 328 in the pole that do not overlap with the d-axis. The provision of the lightening holes 228 and 229 has the effect of further dispersing the stress concentrated on the bridge portion between the magnets between the magnet insertion hole 326 and the magnet insertion hole 327 or between the magnet insertion hole 328 and the magnet insertion hole 327 in the rotor core 320. In addition, by forming the inner corners of the magnet insertion holes 326 and the magnet insertion holes 328 close to the d-axis not in a substantially right angle shape along the permanent magnets 122a and 122c, but in a curved surface with a sufficiently large curvature as shown by the portion highlighted by the bold line at the arrow 338c, the stress concentration can be dispersed. This can be achieved by forming a protrusion-shaped gap 338 as a gap with the permanent magnet 122 c so as to be formed by a curved surface with a large curvature as indicated by the arrow 338 c .

[0056] The corners of the magnet shield of the magnet insertion hole 328 that holds the permanent magnet near the q-axis in the radially outer corners form protrusion-shaped gaps 348 and 358, which are continuous and elongated in the circumferential direction. They are formed into a curved surface with a sufficiently large curvature ( Figure 7 The shape is almost a straight line shape). In this way, since protruding gaps 348 and 358 extending slenderly in the circumferential direction are provided on the outermost side of the third permanent magnet 122c, the rotor core 320 can be made lighter without obstructing the magnetic path of the q-axis. This lightening has the effect of reducing the tensile stress acting on the magnet insertion holes 326 and 328 together with the lightening achieved by the weight-reducing hole 229. The shape of the first magnet insertion hole 326 is the same as that of the third magnet insertion hole 328 relative to the d-axis (reference Figure 6 ) have a symmetrical shape, forming protruding gaps 336, 346, and 356.

[0057] Figure 7 (B) is an enlarged view of the third magnet insertion hole 328. The third magnet insertion hole 326 is a space for accommodating the inserted permanent magnet 122c (with Figure 3 The shapes of the protruding gaps 338, 348, and 358 are connected (equivalent to the shape of the magnet insertion hole 126c shown). Figure 7 The shape of the magnet insertion hole shown in (B) can be manufactured by punching out the electromagnetic steel sheet constituting the rotor core 320 during press working. Here, it should be understood that the protruding gap 338 formed on the side close to the d-axis is not a right-angle shape corresponding to the shape of the inner peripheral side corner of the permanent magnet 122c, but is formed by Figure 7The protruding gap 338 is formed by a curve (curved surface) with an increased curvature radius as shown by arrow 338c in (A). In addition, the curved surface portion near the corner of the protruding gap 338 is extended to the radial outside, forming a cut extending in a manner away from the short side of the permanent magnet 122c close to the d-axis and extending toward the radial outside. That is, the radially extending portion of the protruding gap 338, except for the portion 338a in the projection range of the short side of the permanent magnet 122c, is formed at the front end to extend to the outer position as shown by arrow 342 compared to the imaginary line (imaginary surface) 331 extending the outer side surface of the permanent magnet 122c, so that the stress generated near the arrow 338a can be sufficiently reduced.

[0058] The protruding gap 358 formed on the side close to the q-axis forms about half of the portion around the outer peripheral corner of the permanent magnet 122c formed not with a right angle shape but with a large curve (curved surface) that is roughly linear. The protruding gap 358 extends in the direction of the arrow 334 from the position of the short side of the permanent magnet 122c close to the q-axis (the position shown by the dashed line 333). The extension range is formed to exceed the projection range of the short side close to the q-axis (the range surrounded by the dashed lines 332 and 333) and extend to the direction of the arrow 345. That is, the protruding gap 358 is formed to extend to the inner side position of the virtual line (virtual surface) 332 extending the inner side surface of the permanent magnet 122c, in addition to the portion 358a in the projection range of the short side of the permanent magnet 122c.

[0059] The protrusion-shaped gap 348 extending from the vicinity of the outer corner on the side close to the q-axis extends radially outward from the third permanent magnet 122c toward the d-axis direction. Its extension range is formed to extend toward the side closer to the d-axis than the projection line (dash-dotted line 333) of the short side of the permanent magnet 122c close to the q-axis, that is, the direction of the arrow 343. The protrusion-shaped gap 348 is configured to be connected to the protrusion-shaped gap 358 in the circumferential direction. By forming the protrusion-shaped gap 348 and the protrusion-shaped gap 358, which are sufficiently large compared to the size of the third permanent magnet 122c, in a connected manner, it is possible to achieve sufficient weight reduction of the rotor core 320. In the third embodiment, the stress generated locally can be reduced together with the weight reduction achieved by the weight reduction holes 228 and 229, so that the effect of preventing deformation and fracture of the magnet insertion holes 336 to 338 is further improved.

[0060] The present invention is described above based on three embodiments, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the main purpose. For example, the number of poles of the rotor core can be not only 8 poles, but also other numbers (but an even number). In addition, the number of permanent magnets arranged in one pole can be not only 3, but also 4 or more. In the case of arranging more than 4 permanent magnets in one pole, weight reduction holes can be formed on the inner circumference of the permanent magnets adjacent to the q-axis.

[0061] Description of Reference Numerals

[0062] 1, 1A, 1B…rotating electric machine, 2…housing, 4…rotating shaft, 10…stator, 20, 20A, 20B…rotor, 50…outermost peripheral portion of the lightening hole, 60…innermost peripheral end portion of the magnet insertion hole, 70…innermost peripheral portion of the lightening hole, 81, 82, 83…imaginary line, 102…gap, 104…slot, 110…stator yoke, 112…armature winding, 116…tooth, 120, 220, 320…rotor core, 122a, 122b, 122c…permanent magnet, 123a, 123c…inner peripheral straight line portion of the permanent magnet, 126a, 126b, 126c…magnet insertion hole, 128, 129…lightening hole, 128a , 129a…straight portion (of the lightening hole), 128b, 129b…arc portion (of the lightening hole), 228, 229…lightening hole, 228a, 228b, 229a, 229b…straight portion (of the lightening hole), 228c, 228d, 229c, 229d…arc portion (of the lightening hole), 250…outermost peripheral portion of the lightening hole, 260…innermost peripheral side end portion of the magnet insertion hole, 270…innermost peripheral portion of the lightening hole, 326, 327, 328…magnet insertion hole, 336, 338, 346, 348, 356, 358…protruding gap, A, B, C…distance from the rotation axis, A1…rotation axis (rotation axis).

Claims

1. A rotating electric machine comprising a rotor held rotatably about a rotating shaft and a stator disposed outside the rotor, wherein the rotor has a magnet insertion hole into which a permanent magnet constituting a magnetic pole can be inserted, and the stator has a stator coil, wherein: The magnet insertion holes are arranged symmetrically with the d-axis, which is the central axis of the magnetic pole, as the central axis. A weight-reducing hole is formed on the rotating shaft side of the magnet insertion hole located at a position away from the d-axis among the plurality of magnet insertion holes, The lightening hole is a hole that is continuous in the direction of the rotating shaft, and the shape of the cross section orthogonal to the rotating shaft is formed to include a straight portion and a curved portion, and is formed so that the innermost circumference of the lightening hole closest to the center of the rotating shaft is located in the curved portion, and its curvature is the largest. The magnet insertion hole is spaced a certain distance from the opposing portion of the inner peripheral side of the lightening hole, and the outermost peripheral position of the lightening hole is located on the outer peripheral side compared to the end of the side constituting the magnet insertion hole closest to the central axis of the rotor.

2. The rotating electrical machine according to claim 1, characterized in that: The cross-sectional shape of the lightening hole is formed by a straight portion and a curved portion connecting both ends of the straight portion.

3. The rotating electrical machine according to claim 1, characterized in that: The cross-sectional shape of the lightening hole is formed by two opposing straight portions, a curved portion with a smaller curvature radius connecting ends of one of the two straight portions, and a curved portion with a larger curvature radius connecting ends of the other two straight portions.

4. The rotating electrical machine according to any one of claims 1 to 3, characterized in that: The cross-sectional shape of the plurality of permanent magnets arranged line-symmetrically in one pole with the d-axis as the center is a shape that is long in the rotation direction and short in the radial direction. The permanent magnet disposed at a position overlapping the d-axis is disposed so that the angle between its radial center line and the d-axis is 90 degrees. The permanent magnet disposed at a position not overlapping the d-axis is disposed such that the inclination angle of the radial center line relative to the d-axis is less than 90 degrees and the side farther from the d-axis is located radially outward.

5. The rotating electrical machine according to claim 4, characterized in that: Protrusions for forming curved surfaces with a large curvature radius are formed at locations facing an inner circumferential corner portion on a side close to the d-axis and an outer circumferential corner portion on a side far from the d-axis of the magnet insertion hole.

6. The rotating electrical machine according to claim 4, characterized in that: The cross-sectional shape of the lightening hole is formed such that the two straight line portions are parallel to each other and the width of the parallel portion is shorter than the length of the parallel portion.

7. The rotating electrical machine according to claim 6, characterized in that: The number of the permanent magnets constituting one magnetic pole is an odd number, one of the plurality of permanent magnets is arranged to overlap with the d-axis, and the remaining permanent magnets are arranged at positions not overlapping with the d-axis.

8. The rotating electrical machine according to claim 1, characterized in that: The lightening holes are used as passages for circulating a coolant.

9. A rotating electrical machine, comprising: a stator having stator coils; A rotor having n magnetic poles, wherein a plurality of permanent magnets are inserted in each magnetic pole; and The rotor is fixed to the rotating shaft, The rotating electrical machine is characterized in that: The rotor has a rotor core formed of electromagnetic steel sheets stacked in a rotation axis direction. In each magnetic pole of the rotor core, the second permanent magnet is arranged on the d-axis which is the central axis of the magnetic pole, and the first permanent magnet and the third permanent magnet are arranged in a symmetrical manner about the d-axis. The first to third permanent magnets are formed so that the circumferential width is greater than the radial thickness, and are arranged so that the side close to the p-axis is located radially outward, so that the direction of the circumferential center line and the tangent direction of the rotor core have a predetermined angle (θ), A first lightening hole and a second lightening hole having a semicircular or teardrop-shaped cross-section are formed on the radially inner circumferential side of the first permanent magnet and the third permanent magnet of the rotor core. The first weight-reducing hole is arranged on the inner side of the first permanent magnet, and the second weight-reducing hole is arranged on the inner side of the third permanent magnet. A straight portion is formed in a part of the cross-sectional shape of the first lightening hole and the second lightening hole, and the lightening holes are arranged so that the straight portion is parallel to the opposing long sides of the permanent magnet having a rectangular cross-sectional shape.

10. The rotating electrical machine according to claim 9, characterized in that: The first lightening holes are arranged to partially overlap in a region defined by the first permanent magnet and the axis of the rotating shaft. The second lightening holes are arranged to partially overlap in a region defined by the third permanent magnet and the axis of the rotating shaft.

11. The rotating electrical machine according to claim 10, characterized in that: The outermost peripheral position of the first lightening hole is located on the outer peripheral side of the rotor relative to the end closest to the central axis of the rotor among the sides constituting the insertion hole of the first permanent magnet. The outermost peripheral position of the second lightening hole is located on the outer peripheral side of the rotor relative to the end closest to the central axis of the rotor among the sides constituting the insertion hole for the third permanent magnet.

12. The rotating electrical machine according to claim 11, characterized in that: The first lightening hole and the second lightening hole are formed by two non-parallel straight line portions and two curved lines with different curvature radii connecting both ends of the two straight line portions. In the same pole, the first lightening hole and the second lightening hole are arranged symmetrically about the d-axis.

13. The rotating electrical machine according to claim 11, characterized in that: The first lightening hole and the second lightening hole are formed in a semicircular shape and are symmetrical about the d-axis in the same pole.

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