Rotating electric machines

Abstract

A rotating electric machine (100) is obtained which can effectively suppress deformation and stress imbalance of a rotor (1) and has improved durability. The rotating electric machine (100) is characterized in that it includes a stator (7) and a rotor (1), wherein the rotor (1) includes: a rotor core (2) arranged inside the stator (7), a key portion (22) formed to protrude radially from the inner circumference of the rotor core (2), a stress relief groove (23) provided at both ends of the key portion (22) and formed to be recessed radially outward from the inner circumference of the rotor core (2), and a plurality of balancing holes (31) provided between a plurality of magnetic poles of the rotor core (2), wherein, with respect to the length from the center of the rotor core (2) to the center of each of the plurality of balancing holes (31), the length of a first straight line (d1) passing through the center of the key portion (22) is smaller than the length of an nth straight line (d4) (where n is a natural number > 1) perpendicularly intersecting the first straight line (d1) .

Description

Technical Field

[0001] The present application relates to rotating electrical machines. Background Art

[0002] In the past, the following two structures were used as structures for effectively transmitting torque between the rotor core and the shaft of a rotating electrical machine. The first structure is a key structure in which a convex portion (hereinafter referred to as a key portion) protruding from the inner circumference of the rotor core is engaged with a concave portion (hereinafter referred to as a keyway portion) provided on the outer circumference of the shaft to perform positioning. In addition, the second structure is a structure in which the inner circumference of the rotor core and the outer circumference of the shaft are interference-fitted to transmit torque using the friction force of the contact portion.

[0003] In addition, in a rotating electric machine of an embedded magnet type, stress concentration occurs in a plurality of narrow areas (bridges) sandwiched between the outer peripheral surface of the rotor core and the magnet insertion hole due to the influence of centrifugal force. In the case where a key portion is provided on the rotor core, there is a problem that the stress at the plurality of bridge portions becomes uneven due to the influence of the centrifugal force acting on the key portion. In the past, the following technology has been disclosed as a structure for reducing stress concentration.

[0004] For example, in the rotor of a conventional rotating electrical machine disclosed in Patent Document 1, the following structure is proposed: in a rotor having a plurality of permanent magnets constituting magnetic poles, a rotor core has: a key portion protruding radially inward from an inner circumferential surface of the rotor core; and a recess (balance groove) which is arranged at intervals of a specified angle in the circumferential direction of the rotor core with the key portion as a starting point and is recessed radially outward from the inner circumferential surface of the rotor core.

[0005] In addition, for example, in a previous rotating electrical machine disclosed in Patent Document 2, the following structure is proposed: on a rotor core having a so-called key structure, a triangular hole with a convex strip extending radially toward the outer peripheral surface of the rotor is provided at a position radially inner than the permanent magnets of the rotor core.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2015-220846

[0009] Patent Document 2: Japanese Patent Application Publication No. 2015-061327 Summary of the invention

[0010] Problems to be solved by the invention

[0011] However, according to the above-mentioned Patent Document 1, when the rotor core of the rotary electric machine rotates at a very high speed, the structure for reducing the imbalance of the bridge portion does not take into account the influence of the stress relief groove. When the stress relief groove is provided, it is necessary to consider the influence of the groove to more effectively eliminate the imbalance. In addition, the structure shown in Patent Document 1 further increases the imbalance caused by the centrifugal force acting on the key portion.

[0012] In addition, according to the above-mentioned Patent Document 2, the key portion of the rotor core is engaged with the recessed portion of the shaft to transmit torque, and torque can be transmitted even at high speed, but the goal is to suppress the imbalance of the rigid body caused by eccentricity, and the suppression of imbalance during deformation is not the goal. In addition, the convex strip in the triangular hole needs to be rotated once before the front end is cut.

[0013] Therefore, conventionally, when the rotor of the rotating electric machine rotates at a very high speed, there has been a problem that deformation of the rotor and imbalance of stress occur, and the durability of the rotating electric machine is reduced.

[0014] The present application discloses a technology for solving the above-mentioned problems, and an object of the present application is to obtain a rotating electrical machine that can effectively suppress deformation and stress imbalance of a rotor and has improved durability.

[0015] Solutions to Solve Problems

[0016] The rotating electric machine disclosed in the present application comprises: a stator; and a rotor, wherein the rotor has a rotor core, a key portion, a stress relief groove and a plurality of balancing holes, wherein the rotor core is arranged on the inner side of the stator, the key portion is formed by radially protruding from the inner circumferential surface of the rotor core, the stress relief groove is arranged at both ends of the key portion, and is formed by being recessed radially outward than the inner circumferential surface of the rotor core, and the plurality of balancing holes are respectively arranged between the plurality of magnetic poles of the rotor core, and with respect to the length from the center of the rotor core to the center of each of the plurality of balancing holes, the length of a first straight line passing through the center of the key portion is smaller than the length of an nth straight line (wherein the natural number n>1) perpendicularly intersecting the first straight line.

[0017] Effects of the Invention

[0018] According to the rotating electrical machine disclosed in the present application, it is possible to obtain a rotating electrical machine that can effectively suppress deformation and stress imbalance of the rotor and has improved durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a longitudinal sectional view schematically showing the rotating electrical machine according to the first embodiment.

[0020] Figure 2 It is a plan view showing the rotor of the rotating electrical machine according to the first embodiment.

[0021] Figure 3 Yes Figure 2 A partially enlarged top view.

[0022] Figure 4 It is a plan view for explaining the installation position of the balancing hole in the rotor of the rotating electric machine according to the first embodiment.

[0023] Figure 5A It is a plan view showing a 1 / 4 region of the rotor of Comparative Example 1.

[0024] Figure 5B Yes means Figure 5A A top view of the rotor showing its deformed state when rotating.

[0025] Figure 6 Is used for Figure 5A The top view shown is used to illustrate the effect of the balancing groove.

[0026] Fig. 7A It is a plan view showing a 1 / 4 region of the rotor of Comparative Example 2.

[0027] Figure 7B Yes means Fig. 7A A top view of the rotor showing its deformed state when rotating.

[0028] Fig. 8A It is a plan view showing a 1 / 4 region of the rotor of Comparative Example 3.

[0029] Figure 8B Yes means Fig. 8A A top view showing the contact distribution of the rotor with the shaft when the rotor rotates.

[0030] Fig.9A It is a plan view showing a 1 / 4 region of the rotor of Comparative Example 4.

[0031] Fig. 9B Yes means Fig.9A A top view showing the contact distribution of the rotor with the shaft when the rotor rotates.

[0032] Fig. 10A It is a plan view showing a 1 / 4 region of the rotor of the rotating electrical machine according to the first embodiment.

[0033] Fig. 10B Yes means Fig. 10A A top view of the rotor showing its deformed state when rotating.

[0034] Fig.11A This is a diagram comparing the stress of the rotor of the rotating electrical machine according to the first embodiment and the rotors of the first and second comparative examples.

[0035] Fig. 11BThis is a diagram comparing the radial contact force of the rotor of the rotating electrical machine according to the first embodiment and the rotors of the third and fourth comparative examples.

[0036] Fig. 12A It is a plan view showing Modification 1 of the rotating electrical machine according to the first embodiment.

[0037] Fig. 12B It is a plan view showing a second modification of the rotating electrical machine according to the first embodiment.

[0038] Fig. 12C It is a plan view showing a third modification of the rotating electrical machine according to the first embodiment.

[0039] Fig.13 This is a diagram comparing the stresses of the outer peripheral bridge portions of the rotors of Modifications 1, 2, and 3 of the rotating electrical machine according to Embodiment 1 and the rotor of Comparative Example 2.

[0040] Fig.14 It is a plan view showing a rotor of a rotating electrical machine according to the second embodiment.

[0041] Fig.15 It is a plan view for explaining the installation position of the balancing hole in the rotor of the rotating electric machine according to the second embodiment.

[0042] Fig.16A It is a plan view showing a 1 / 4 region of the rotor of the rotating electrical machine according to the second embodiment.

[0043] Fig. 16B Yes means Fig.16A A top view of the rotor showing its deformed state when rotating.

[0044] Fig.17A This is a diagram comparing the stress of the rotor of the rotating electrical machine according to the second embodiment and the rotors of the first and second comparative examples and the first embodiment.

[0045] Fig. 17B This is a diagram comparing the radial contact force of the rotor of the rotating electrical machine according to the second embodiment and the rotors of the third and fourth comparative examples and the first embodiment. DETAILED DESCRIPTION

[0046] Hereinafter, the rotating electrical machine according to the first embodiment will be described based on the drawings.

[0047] It should be noted that, in the drawings, the same reference numerals denote the same or corresponding components.

[0048] Implementation method 1.

[0049] Figure 1 FIG. 1 is a longitudinal sectional view schematically showing the rotating electrical machine according to the first embodiment. Figure 1In the embodiment, the rotating electric machine 100 includes a stator 7 and a rotor 1, and the rotor 1 includes a rotor core 2, a permanent magnet 3 embedded in the rotor core 2, and a shaft 4 that passes through the inner periphery of the rotor core 2. In the first embodiment, the permanent magnet 3 is divided into a plurality of parts in the axial direction. The rotor core 2 and the shaft 4 are fitted together via a key structure provided by press-fitting, shrink-fitting, or the inner periphery of the rotor core 2 and the outer periphery of the shaft 4. In addition, the stator 7 includes a stator core 5 in which a plurality of steel plates are stacked in the axial direction, and a coil 6 wound on the stator core 5. It should be noted that the rotation center of the stator 7 coincides with the mass center of gravity, and a plate for balancing adjustment may be added.

[0050] Figure 2 FIG. 1 is a top view showing the rotor of the rotating electrical machine according to Embodiment 1. Figure 2 In the embodiment, 24 magnet insertion holes 21 are arranged in the rotor core 2, and 24 permanent magnets 3 are buried in the magnet insertion holes 21. The permanent magnets 3 arranged in the magnet insertion holes 21 are grouped in two, and 12 groups of permanent magnets 3 are arranged in a V shape in a state extending from the center side of the shaft 4 toward the outer peripheral side. One magnetic pole is composed of two magnet insertion holes 21 arranged in a V shape and two permanent magnets 3, and the 12 magnetic poles are arranged in the circumferential direction. In addition, a balancing hole 31 is provided between the magnetic poles.

[0051] The shaft 4 is arranged on the inner circumference of the rotor core 2. In order to effectively transmit torque between the rotor core 2 and the shaft 4, the rotor core 2 is provided with a key portion 22 protruding radially inward from the inner circumference of the rotor core 2, and the shaft 4 is provided with a key groove portion 41 engaged with the key portion 22 on the outer circumference of the shaft 4. The key portion 22 and the key groove portion 41 form a key structure, and the key structure is provided at two locations in a manner of facing each other at 180 degrees.

[0052] Next, the inner peripheral structure of the rotor core 2 will be described. Figure 3 Yes Figure 2 A partial enlarged top view. Figure 3 , the structure of the key portion 22 and the inner peripheral portion of the rotor core 2 of the rotating electrical machine 100 according to the first embodiment will be described. Figure 3 , axis 4 is omitted.

[0053] On the inner circumferential surface of the rotor core 2, in order to alleviate the stress concentration caused by the circumferential tensile stress on the key portion 22, stress relief grooves 23 are provided at both ends of the key portion 22, which are connected to the outer circumferential side of the key side surface 221 and are recessed in the direction away from the outer circumferential surface of the shaft 4.

[0054] The stress relief groove 23 of the first embodiment includes a first arc 23R1 connected to the outer peripheral side of the key side surface 221 and a second arc 23R2 smoothly connected to the first arc 23R1 and extending along the inner peripheral surface of the rotor core 2 .

[0055] In addition, in order to suppress the deformation imbalance and stress imbalance of the peripheral bridging portion 271 and the rotor core 2 which are sandwiched between the magnet insertion hole 21 and the outer peripheral surface of the rotor core 2 during high-speed rotation, a balancing hole 31 is provided as a punching hole between adjacent magnetic poles to achieve lightweight and reduce the stress acting on the magnet insertion hole 21.

[0056] Next, the installation positions of the balancing holes 31 in the rotor 1 of the rotating electrical machine 100 according to the first embodiment will be described. Figure 4 FIG. 1 is a top view for explaining the position of the balancing hole in the rotor of the rotating electrical machine according to the first embodiment. Figure 4 In FIG. 1 , only 1 / 4 of the rotor 1 of the rotating electrical machine 100 according to the first embodiment is shown, and the shaft 4 is omitted.

[0057] exist Figure 4 In the figure, the center of the rotor core 2 is taken as the starting point 8, the key portion 22 is divided into two equal parts by the center of the key portion 22, and the half straight line passing through the balancing hole 31 is defined as the first balancing hole center line 311L, which is indicated by a single-dot chain line. In addition, the center of the rotor core 2 is taken as the starting point 8, and the half straight line perpendicularly intersecting the first balancing hole center line 311L is defined as the fourth balancing hole center line 314L, which is indicated by a single-dot chain line. Furthermore, the center of the rotor core 2 is taken as the starting point 8, and the half straight lines passing through the center of the balancing hole 31 existing from the first balancing hole center line 311L to the fourth balancing hole center line 314L when viewed in the circumferential direction are respectively defined as the second balancing hole center line 312L and the third balancing hole center line 313L, which are indicated by single-dot chain lines.

[0058] In the rotor 1 of the rotating electrical machine 100 according to the first embodiment, as Figure 4 As shown, with the center of the rotor core 2 as the starting point 8, the straight lines to the center of the balancing hole 31 on the first balancing hole center line 311L, the second balancing hole center line 312L, the third balancing hole center line 313L and the fourth balancing hole center line 314L are defined as d1, d2, d3 and d4 respectively, so that the balancing hole 31 is arranged in a manner that makes equations (1) and (2) valid.

[0059] d4≥d3≥d2≥d1 (1)

[0060] d4>d1 (2)

[0061] Figure 5A is a top view showing a 1 / 4 region of the rotor of Comparative Example 1, Figure 5B Yes means Figure 5A The top view of the rotor in the deformed state when rotating is shown. Figure 6 Is used for Figure 5A The top view shown in the figure is used to illustrate the effect of the balance groove. Figure 5A , Figure 5B , Figure 6 Comparative Example 1 is verified to verify the action and effect of Embodiment 1.

[0062] exist Figure 5A In the present invention, the rotor 1 as the comparative example 1 includes the permanent magnet 3 embedded in the rotor core 2, the key portion 22, the balancing groove 24 and the balancing hole 31, and does not include the stress relief groove 23. The balancing groove 24 is provided at the same angle as the angle constituting each magnetic pole, starting from the key portion 22, and adopts the same structure as that of Patent Document 1.

[0063] in addition, Figure 5B express Figure 5A The deformation state of the rotor when rotating shown in the figure specifically shows the original shape line 11 of the rotor core 2 and the deformation line 10 of the rotor core 2 when the rotor 1 is rotated at 13000 rpm, which are magnified 200 times. The installation direction of the key portion 22 is set as the X-axis, and the direction orthogonal to the X-axis is set as the Y-axis. Here, Figure 5A as well as Figure 5B Symmetrical with respect to the X-axis and the Y-axis.

[0064] The result of rotating the rotor 1 under the above conditions is that Figure 5B As shown in FIG. 1 , the deformation amount A in the X-axis direction becomes larger than the deformation amount B in the Y-axis direction. That is, the rotor core 2 is deformed into an ellipse convex in the X-axis direction. Figure 5B In the formula, the deformation amount A is obtained by adding the centrifugal force acting on the rotor 1 to the centrifugal force acting on the key portion 22 and the reduction in circumferential rigidity caused by the balancing groove 24 (deformation amount A: centrifugal force acting on the rotor 1 + centrifugal force acting on the key portion 22 + reduction in circumferential rigidity caused by the balancing groove 24). In addition, the deformation amount B is obtained by subtracting the centrifugal force acting on the balancing groove 24 from the centrifugal force acting on the rotor 1 (deformation amount B: centrifugal force acting on the rotor 1 - centrifugal force acting on the balancing groove 24).

[0065] Here, the rotor 1 of Comparative Example 1 is used. Figure 6 The effect of the balancing tank 24 will be described. Figure 6 In FIG. 1 , arrow C indicates deformation imbalance caused by the disappearance of the centrifugal force generated in the balancing groove 24 , and arrow D indicates deformation imbalance caused by the reduction of circumferential rigidity. The effects of the balancing groove 24 can be listed in two examples.

[0066] First, by providing the balancing grooves 24, the centrifugal force acting on the rotor core 2 is reduced, and radial deformation is suppressed. This deformation suppression effect is produced locally at the angle where the balancing grooves 24 are provided on the rotor core 2. Figure 6 In the rotor 1 , the radial deformation amount at the angle where the balancing groove 24 is provided is larger than the radial deformation amount in the key portion direction (X-axis direction) where the balancing groove 24 is not provided.

[0067] Secondly, the cross-sectional area 26d of the inner circumference of the rotor core 2 is reduced by the balancing groove 24, thereby reducing the rigidity of the inner circumference and increasing the circumferential deformation. This deformation increase effect occurs locally at the angle of the rotor core 2 where the balancing groove 24 is provided. In addition, if the circumferential deformation at a certain position increases, the radial deformation in the direction orthogonal to the increased position increases. That is, at Figure 6 In the rotor 1 , the radial deformation amount in the key portion 22 direction (X-axis direction) where the balancing groove 24 is not provided is larger than the radial deformation amount at the angle where the balancing groove 24 is provided.

[0068] In Comparative Example 1, the radial deformation in the X-axis direction increases by providing the key portion 22, and the circumferential rigidity decreases and the circumferential deformation increases by providing the balancing groove 24. Along with this, the deformation amount in the orthogonal radial direction also increases, but the radial deformation is offset by the suppression effect of the radial deformation brought about by the reduction of the centrifugal force. Therefore, the remaining circumferential deformation is added to the change amount A in the X-axis direction.

[0069] Fig. 7A is a top view showing a 1 / 4 region of the rotor of Comparative Example 2, Figure 7B Yes means Fig. 7A The top view of the rotor in the deformed state when rotating is shown. Fig. 7A In the figure, the rotor 1 as the comparative example 2 includes the permanent magnets 3 embedded in the rotor core 2 , the key portions 22 , the stress relaxation grooves 23 , and the balancing holes 31 , but does not include the balancing grooves 24 .

[0070] in addition, Figure 7B express Fig. 7A The deformation state of the rotor when rotating shown in the figure specifically shows the original shape line 11 of the rotor core 2 and the deformation line 10 of the rotor core 2 when the rotor 1 is rotated at 13000 rpm, which are magnified 200 times. The installation direction of the key portion 22 is set as the X-axis, and the direction orthogonal to the X-axis is set as the Y-axis. Here, Fig. 7A as well as Figure 7B Symmetrical with respect to the X-axis and the Y-axis.

[0071] The result of rotating the rotor 1 under the above conditions is that Figure 7B As shown in FIG. 1 , it can be seen that the deformation amount E in the Y-axis direction is larger than the deformation amount F in the X-axis direction. That is, the rotor core 2 is deformed into an ellipse convex in the Y-axis direction. Figure 7BIn the formula (a), the deformation E is the centrifugal force acting on the rotor 1 plus the reduction in circumferential rigidity caused by the stress relief groove 23 (deformation E: centrifugal force acting on the rotor 1 + reduction in circumferential rigidity caused by the stress relief groove 23). In addition, the deformation F is the centrifugal force acting on the rotor 1 plus the centrifugal force acting on the key portion 22 minus the centrifugal force acting on the stress relief groove 23 (deformation F: centrifugal force acting on the rotor 1 + centrifugal force acting on the key portion 22 - centrifugal force acting on the stress relief groove 23).

[0072] In Comparative Example 2, two problems occur due to the imbalance of stress and the imbalance of deformation.

[0073] The first is the reduction in durability caused by stress imbalance. When the rotor 1 rotates at high speed, due to the deformation of the rotor core 2, the outer peripheral bridge portions 271B-276B and the balance holes 31 of each magnetic pole become stress concentration portions and generate high stress. If the deformation shape of each magnetic pole is uniform, the stress acting on the stress concentration portion will also become uniform, but in the rotor core 2 of Comparative Examples 1 and 2, the stress acting on the stress concentration portion becomes uneven due to stress imbalance, and the durability of the rotor core 2 is reduced.

[0074] The second is the reduction in the damage speed caused by the imbalance of deformation. The rotor 1 of the rotating electrical machine 100 preferably determines the allowable speed in consideration of static strength and fatigue limit, and is controlled not to rotate above the maximum speed. However, in the rotating electrical machines 100 used in electric vehicles, hybrid vehicles, etc., the rotor 1 is sometimes forced to rotate at a speed exceeding the allowable speed due to the transmission of rotation from the drive system. If the allowable speed is exceeded, the rotor core 2 plastically deforms toward the outer diameter side, and if the radial deformation exceeds the gap width between the rotor core 2 and the stator core 5, the rotor core 2 contacts the stator core 5 and causes the rotating electrical machine 100 to be damaged. In the rotor core 2 of Comparative Examples 1 and 2, due to the imbalance of deformation, the convex side of the elliptical deformation preferentially contacts the stator core 5, and therefore, the damage speed is reduced.

[0075] Here, the effect of the stress relief groove 23 is described. Figure 6 The effects of the balancing groove 24 described above are similarly two effects of reducing the centrifugal force and reducing the circumferential rigidity, and unbalance is generated so that the deformation in the Y-axis direction is larger than the deformation in the X-axis direction.

[0076] In Comparative Example 2, the increase in Y-direction deformation due to the stress relaxation groove 23 exceeds the increase in X-direction deformation due to the key portion 22 , which causes an elliptical deformation that is convex in the Y-axis direction.

[0077] In Comparative Example 2, if the balance between the X-direction deformation caused by the key portion 22 and the Y-direction deformation of the stress relief groove 23 can be ensured, the imbalance can be eliminated, but the stress relief groove 23 needs to be composed of a large-diameter arc or the like in order to reduce the stress acting on the key portion 22, so it is difficult to ensure the balance with the key portion 22. In addition, the key portion 22 is unbalanced due to the increase in centrifugal force, but the stress relief groove 23 is unbalanced due to the two effects of the reduction of centrifugal force and the reduction of circumferential rigidity. Therefore, in order to ensure the balance, the size of the stress relief groove 23 needs to be about 1 / 2 of the size of the key portion 22, which makes the design more difficult.

[0078] Fig. 8A is a top view showing a 1 / 4 region of the rotor of Comparative Example 3, Figure 8B Yes means Fig. 8A A top view showing the contact distribution of the rotor with the shaft when the rotor rotates.

[0079] exist Fig. 8A In the figure, the rotor 1 as the comparative example 3 includes the permanent magnet 3 embedded in the rotor core 2, the key portion 22, the stress relief groove 23, the balance hole 31, the balance groove 24 and the shaft 4. The rotor core 2 is fitted to the shaft 4 by press-fitting. Figure 8B Indicates Fig. 8A The contact distribution of the press-fit portion between the rotor core 2 and the shaft 4 when the rotor 1 rotates at 13000 rpm is shown.

[0080] in addition, Fig.9A is a top view showing a 1 / 4 region of the rotor of Comparative Example 4, Fig. 9B Yes means Fig.9A A top view showing the contact distribution of the rotor with the shaft when the rotor rotates.

[0081] exist Fig.9A In the figure, the rotor 1 of Comparative Example 4 includes the permanent magnets 3 embedded in the rotor core 2, the key portion 22, the stress relaxation groove 23, the balancing hole 31 and the shaft 4, but does not include the balancing groove 24. The rotor core 2 is fitted to the shaft 4 by press fitting.

[0082] in addition, Fig. 9B Indicates Fig.9A The contact distribution of the press-fit portion between the rotor core 2 and the shaft 4 when the rotor 1 rotates at 13000 rpm is shown. Compared with Comparative Example 3, Comparative Example 4 shows that the contact distribution of the press-fit portion between the rotor core 2 and the shaft 4 is a wide area. That is, it is known that the contact area between the rotor core 2 and the shaft 4 is larger in Comparative Example 4 than in Comparative Example 3, and the torque transmitted is larger.

[0083] Here, the transmission of torque will be described. There are two methods for transmitting torque between the rotor core 2 of the rotor 1 and the shaft 4 in the rotating electrical machine 100.

[0084] The first is a key structure for positioning by fitting a key portion 22 protruding from the inner circumferential surface of the rotor core 2 to the inner circumferential side into a key groove portion 41 provided on the outer circumferential surface of the shaft 4. This key structure can transmit torque between the rotor core 2 and the shaft 4 even during high-speed rotation, but there is a problem of reduced positioning accuracy between the rotor core 2 and the shaft 4 due to looseness caused by the increase in the inner diameter of the rotor core 2 caused by centrifugal force or the dimensional tolerance of the key portion 22.

[0085] The second is a structure in which the inner circumference of the rotor core 2 and the outer circumference of the shaft 4 are set to an interference fit by press-fit or shrink-fit, and the torque is transmitted by the friction force of the contact portion. This structure has the following problems: when rotating at high speed, the rotor core 2 is separated from the shaft 4 due to centrifugal force. If the inner diameter of the rotor core 2 increases and the interference is eliminated, the torque cannot be transmitted.

[0086] Therefore, a structure that cancels out the problems of each other by using the above-mentioned two structures together is often used.

[0087] Fig. 10A 1 is a plan view showing a 1 / 4 region of the rotor of the rotating electrical machine according to the first embodiment. Fig. 10B Yes means Fig. 10A A top view of the rotor showing its deformed state when rotating.

[0088] exist Fig. 10A In the embodiment 1, the rotor 1 has a permanent magnet 3 embedded in the rotor core 2, a key portion 22, a stress relief groove 23, and a balancing hole 31. That is, the straight lines d1, d2, d3, and d4 from the center of the rotor core 2 as the starting point 8 to the center of each balancing hole 31 are in the relationship of formula (3). It should be noted that in the embodiment 1, the size of the straight line d4 is used as a reference.

[0089] d4>d3>d2>d1(3)

[0090] in addition, Fig. 10B express Fig. 10A The deformation state of the rotor 1 when rotating is shown, specifically, a state where the original shape line 11 of the rotor core 2 and the deformation line 10 of the rotor core 2 when the rotor 1 is rotated at 13000 rpm are magnified 200 times. The mounting direction of the key portion 22 is set as the X-axis, and the direction orthogonal to the X-axis is set as the Y-axis. Fig. 10A as well as Fig. 10B Symmetrical with respect to the X-axis and the Y-axis.

[0091] exist Fig. 10BIt can be seen that the deformation E in the Y-axis direction is greater than the deformation F in the X-axis direction. That is, the rotor core 2 is deformed into an ellipse convex in the Y-axis direction. The deformation in the Y-axis direction is greater than that in Comparative Example 1, but smaller than that in Comparative Example 2. That is, the rotor 1 of the rotating electrical machine 100 according to Embodiment 1 can suppress deformation imbalance during rotation compared with Comparative Example 2. The deformation E is the centrifugal force acting on the rotor 1 plus the reduction in circumferential rigidity caused by the stress relief groove 23 (deformation E: centrifugal force acting on the rotor 1 + reduction in circumferential rigidity caused by the stress relief groove 23). In addition, the deformation F is the centrifugal force acting on the rotor 1 plus the centrifugal force acting on the key portion 22 and minus the centrifugal force acting on the stress relief groove 23 (deformation F: centrifugal force acting on the rotor 1 + centrifugal force acting on the key portion 22 - centrifugal force acting on the stress relief groove 23).

[0092] Fig.11A This is a diagram comparing the stress of the rotor of the rotating electrical machine of Embodiment 1 with the stress of the rotors of Comparative Examples 1 and 2. Fig. 11B This is a diagram comparing the radial contact force of the rotor of the rotating electrical machine according to the first embodiment and the rotors of the third and fourth comparative examples.

[0093] Here, the stress of Embodiment 1 is compared with Comparative Examples 1 and 2, and the radial contact force of Embodiment 1 is compared with Comparative Examples 3 and 4. The stress and the radial contact force are evaluated by the rotor core 2 when the rotor 1 is rotated at 13000 rpm. Fig.11A The maximum stresses acting on the peripheral bridge portions 271B-276B and their standard deviations are shown. Fig. 11B Represents the radial contact force between the rotor core 2 and the shaft 4.

[0094] according to Fig.11A , the maximum stress at the outer peripheral bridge portion 271B-276B in Embodiment 1 is lower than the maximum stress in Comparative Example 2. In addition, since the standard deviation of the maximum stress acting on the outer peripheral bridge portion 271B-276B is also lower than that in Comparative Example 2, it can be seen that stress non-uniformity is suppressed in Embodiment 1, and the rotor core 2 has higher durability. In Comparative Example 1, it can be seen that by using Figure 6 The effect of the balancing groove 24 described above can suppress the uneven stress as in the first embodiment, and the rotor core 2 has high durability. Fig. 11B As shown, focusing on the radial contact force, the first embodiment exceeds the radial contact force of the comparative examples 3 and 4. That is, the first embodiment can maintain a larger transmission torque between the rotor core 2 and the shaft 4 than the comparative examples 3 and 4.

[0095] Based on the above two points, Embodiment 1 can provide a structure in which the uniformity of the stress of the outer peripheral bridge portions 271B-276B is similar to that of Comparative Example 1, but the holding torque can be kept high, thereby preventing the rotor core 2 and the shaft 4 from separating during high-speed rotation.

[0096] Here, the rotor 1 of the first embodiment is used. Fig. 10A The following describes the effects of changing the installation position of the balancing hole 31. There are two effects obtained by setting the installation position of the balancing hole 31 as shown in the formula (3).

[0097] First, by reducing the distance from the center of the rotor core 2 to the center of the balancing hole 31, the centrifugal force acting on the rotor core 2 is reduced, and radial deformation is suppressed. This deformation suppression effect occurs locally at the location where the position of the balancing hole 31 is changed. Fig. 10A In the rotor 1 shown, the radial deformation amount in the direction (X-axis direction) in which the length to the center of the balancing hole 31 is reduced is larger than the radial deformation amount in the direction (Y-axis direction) in which the length is increased.

[0098] Secondly, by making the straight line d1 on the first balancing hole centerline 311L shorter than the straight line d4 on the fourth balancing hole centerline 314L, the rigidity of the inner circumference is reduced and the circumferential deformation is increased. If the circumferential deformation at a certain position increases, the radial deformation in the direction orthogonal to the increased position increases.

[0099] That is, in Fig. 10A In the rotor 1, the radial deformation amount in the direction (X-axis direction) in which the length of the straight line d1 to the center of the balancing hole 31 is reduced is larger than the radial deformation amount in the direction of the straight line d4 (Y-axis direction).

[0100] As can be seen from the effects described above, the rotor core 2 of the first embodiment promotes deformation in the X-axis direction compared to the second comparative example, and can suppress the unbalanced deformation that becomes elliptical and convex in the Y-axis direction.

[0101] Fig. 12A is a plan view showing a first modification of the rotating electrical machine according to the first embodiment, Fig. 12B 1 is a plan view showing a second modification of the rotary electric machine of the first embodiment. Fig. 12C It is a plan view showing a third modification of the rotating electrical machine according to the first embodiment.

[0102] like Fig. 12A As shown, the first modification of the first embodiment shows a structure in which the straight line d1 to the center of the balancing hole 31 is simply made shorter than d4. That is, Fig. 12A The straight lines d1 to d4 extending from the center of the balancing hole 31 of the rotor core 2 shown in FIG. 2 are in the relationship of the equation (4).

[0103] d4=d3=d2>d1 (4)

[0104] Then, if Fig. 12B As shown, the second modification of the first embodiment shows a structure in which the straight lines d1 and d2 to the center of the balancing hole 31 are equal and shorter than d4. That is, Fig. 12B The straight lines d1 to d4 from the rotor core 2 to the center of the balancing hole 31 are in the relationship of the equation (5).

[0105] d4=d3>d2=d1 (5)

[0106] And, if Fig. 12C As shown, the modification 3 of the first embodiment shows a structure in which the straight lines d1, d2 and d3 to the center of the balancing hole 31 are equal and shorter than d4. That is, Fig. 12C The straight lines d1 to d4 from the rotor core 2 to the center of the balancing hole 31 are in the relationship of the equation (6).

[0107] d4>d3=d2=d1 (6)

[0108] Here, the stresses of Modification 1, Modification 2, Modification 3 and Comparative Example 2 of Embodiment 1 are compared. FIG. 12A to FIG. 12C The rotor 1 shown was evaluated while the rotor core 2 was rotating at 13,000 rpm.

[0109] Fig.13 This is a diagram comparing the maximum stress acting on the outer peripheral bridge portions 271B-276B of the rotors of Modifications 1, 2, and 3 of the rotating electrical machine of Embodiment 1 and the rotor of Comparative Example 2. Fig.13 As shown, it can be seen that the maximum stresses of Modification 1, Modification 2, and Modification 3 of Embodiment 1 are all lower than the maximum stress of Comparative Example 2.

[0110] That is, it can be seen that by making the positions of the balancing holes 31 other than the balancing holes 31 on the fourth balancing hole center line 314L closer than d4, it is possible to suppress the imbalance and reduce the stress acting on the outer peripheral bridge portion 271B-276B. That is, according to equations (3) to (6), it can be seen that the structure of the rotor 1 that satisfies equations (1) and (2) is an effective structure for suppressing stress imbalance.

[0111] d4≥d3≥d2≥d1 (1)

[0112] d4>d1 (2)

[0113] As described above, according to the rotating electric machine 100 of embodiment 1, it is characterized by comprising: a stator 7; and a rotor 1, wherein the rotor 1 has a rotor core 2, a key portion 22, a stress relief groove 23 and a plurality of balancing holes 31, wherein the rotor core 2 is arranged on the inner side of the stator 7, the key portion 22 is formed to protrude radially from the inner circumferential surface of the rotor core 2, the stress relief groove 23 is provided at both ends of the key portion 22, and is formed to be recessed radially outward from the inner circumferential surface of the rotor core 2, and the plurality of balancing holes 31 are respectively provided between the plurality of magnetic poles of the rotor core 2, and with respect to the length from the center of the rotor core 2 to the center of each of the plurality of balancing holes 31, the length of a first straight line d1 passing through the center of the key portion 22 is smaller than the length of an nth straight line dn perpendicularly intersecting the first straight line d1.

[0114] In addition, according to the rotating electric machine 100 of embodiment 1, it is characterized in that, when a first straight line to the center of the balancing hole 31 on the half straight line passing through the center of the key portion 22 is defined as d1 with the center of the rotor core 2 as the starting point 8, an nth straight line to the center of the balancing hole 31 on the half straight line perpendicularly intersecting the first straight line d1 is defined as dn with the center of the rotor core 2 as the starting point 8, and straight lines to the center of a plurality of balancing holes 31 between each magnetic pole sandwiched by the two balancing holes 31 (the balancing holes on the first straight line and the balancing holes on the nth straight line) in the circumferential direction are defined as d2, d3, ..., dn-1 in the order of approaching the first straight line, i.e., the balancing hole 31 on d1, d1 to dn satisfy equations (7) and (8) (wherein the natural number n>1).

[0115] dn≥dn-1≥...≥d1 (7)

[0116] dn>d1 (8)

[0117] According to the rotating electric machine 100 of embodiment 1, the following rotating electric machine 100 can be provided: when a key portion 22 is provided on the inner circumference of the rotor core 2 and stress relief grooves 23 are provided at both ends of the key portion 22, by making the positions of the balancing holes 31 provided between the magnetic poles non-uniform, the contact area between the rotor core 2 and the shaft 4 can be ensured and the separation of the two can be prevented, and the deformation imbalance and stress imbalance of the rotor core 2 caused by the key portion 22 and the stress relief groove 23 can be effectively suppressed, thereby improving durability.

[0118] Implementation method 2.

[0119] Fig.14 FIG. 1 is a top view showing a rotor of a rotating electrical machine according to Embodiment 2. Fig.14In the figure, the parts marked with the same reference numerals as those used to explain the rotating electrical machine 100 in the first embodiment represent the same or corresponding structures, and their description is omitted. In the rotor core 2 in the second embodiment, in order to suppress deformation imbalance and stress imbalance during high-speed rotation, punching holes (non-uniform balancing holes 31H, 32H, 33H, 34H) of non-uniform shapes are provided between adjacent magnetic poles for achieving weight reduction and reducing stress acting on the magnet insertion hole 21.

[0120] Fig.15 It is a plan view for explaining the installation position of the balancing hole in the rotor of the rotating electric machine according to the second embodiment. Fig.15 The rotor 1 of the rotating electrical machine 100 according to the second embodiment is shown in an enlarged manner with only 1 / 4 thereof being shown, and the shaft 4 is omitted.

[0121] like Fig.15 As shown, the rotor 1 of the rotating electrical machine of embodiment 2 defines the areas of the balancing holes on the first balancing hole center line 311L, the second balancing hole center line 312L, the third balancing hole center line 313L and the fourth balancing hole center line 314L as S1, S2, S3 and S4 respectively, and arranges the balancing holes 31H, 32H, 33H and 34H in a manner that makes equations (1), (2) and (9) hold.

[0122] S4≤S3≤S2≤S1 (9)

[0123] Fig.16A is a plan view showing a 1 / 4 region of the rotor of the rotating electrical machine according to the second embodiment, Fig. 16B Yes means Fig.16A A top view of the rotor showing its deformed state when rotating.

[0124] exist Fig.16A In the embodiment 2, the rotor 1 includes the permanent magnets 3 embedded in the rotor core 2, the key portion 22, the stress relief groove 23, and the non-uniform balancing holes 31H, 32H, 33H, 34H. That is, the straight lines d1, d2, d3, d4 and the areas S1, S2, S3, S4 of the non-uniform balancing holes 31H, 32H, 33H, 34H are in the relationship of equations (3), (2), and (9).

[0125] d4>d3>d2>d1 (3)

[0126] d4>d1 (2)

[0127] S4≤S3≤S2≤S1 (9)

[0128] in addition, Fig. 16B express Fig.16AThe deformation state of the rotor 1 when rotating is shown, specifically, a state where the original shape line 11 of the rotor core 2 and the deformation line 10 of the rotor core 2 when the rotor 1 is rotated at 13000 rpm are magnified 200 times. The mounting direction of the key portion 22 is set as the X-axis, and the direction orthogonal to the X-axis is set as the Y-axis. Fig.16A as well as Fig. 16B Symmetrical with respect to the X-axis and the Y-axis.

[0129] Here, the stresses of Embodiment 2 and Comparative Example 1, Comparative Example 2 and Embodiment 1, and the radial contact forces of Embodiment 2 and Comparative Example 3, Comparative Example 4 and Embodiment 1 are compared.

[0130] Fig.17A This is a graph comparing the maximum stresses acting on the outer peripheral bridge portions 271B-276B of the rotor of the rotating electrical machine of Embodiment 2 and the rotors of Comparative Example 1, Comparative Example 2, and Embodiment 1, and their standard deviations. Fig. 17B This is a diagram comparing the radial contact force between the rotor core 2 and the shaft 4 of the rotor of the rotating electrical machine according to the second embodiment and the rotors of the third and fourth comparative examples and the first embodiment.

[0131] like Fig.17A As shown, the maximum stress at the outer peripheral bridge portion of the rotor 1 of the rotating electrical machine 100 of the second embodiment is lower than that of the comparative example 2. In addition, the standard deviation of the maximum stress acting on the outer peripheral bridge portions 271B-276B is lower than that of the comparative examples 1, 2 and the first embodiment.

[0132] That is, it can be seen that the rotor 1 of the rotating electric machine 100 of the second embodiment not only makes the installation positions of the balancing holes 31H, 32H, 33H, and 34H non-uniform, but also makes the areas of the balancing holes 31H, 32H, 33H, and 34H non-uniform, thereby further suppressing stress non-uniformity compared with the first embodiment, and is a rotor 1 with high durability. In addition, if the radial contact force is focused, the rotor 1 of the rotating electric machine 100 of the second embodiment exceeds the comparative example 3 and is at the same level as the comparative example 4 and the first embodiment. That is, the rotor 1 of the rotating electric machine 100 of the second embodiment can maintain the transmission torque between the rotor core 2 and the shaft 4 to the same level or greater than the comparative examples 3 and 4.

[0133] Thus, the second embodiment can provide a rotating electrical machine 100 that can solve the uneven stress of the outer peripheral bridge portions 271B to 276B and maintain a high holding torque between the rotor core 2 and the shaft 4 .

[0134] As described above, according to the rotating electric machine 100 of the second embodiment, similarly to the rotating electric machine of the first embodiment, it is characterized by comprising: a stator 7; and a rotor 1, wherein the rotor 1 has a rotor core 2, a key portion 22, a stress relief groove 23, and a plurality of balancing holes 31H, 32H, 33H, and 34H, wherein the rotor core 2 is arranged on the inner side of the stator 7, the key portion 22 is formed to protrude in the radial direction from the inner peripheral surface of the rotor core 2, the stress relief groove 23 is provided at both ends of the key portion 22, and is formed to be recessed radially outward relative to the inner peripheral surface of the rotor core 2, the plurality of balancing holes 31H, 32H, 33H, and 34H are respectively provided between the plurality of magnetic poles of the rotor core 2, and with respect to the length from the center of the rotor core 2 to the center of each of the plurality of balancing holes 31H, 32H, 33H, and 34H, the length of a first straight line d1 passing through the center of the key portion 22 is smaller than the length of an n-th straight line dn (wherein the natural number n>1) perpendicularly intersecting the first straight line d1.

[0135] Furthermore, according to the rotating electric machine 100 of embodiment 2, it is characterized in that, when a first straight line from the center of the rotor core 2 to the center of the balancing hole 31H on the half straight line passing through the center of the key portion 22 is defined as d1, and a n-th straight line from the center of the rotor core 2 to the center of the balancing hole 34H on the half straight line perpendicularly intersecting the first straight line d1 is defined as dn, an area of ​​the balancing hole 31H on the first straight line, i.e., d1, is defined as S1, and the areas of the balancing holes 34H on the n-th straight line, i.e., dn, which are adjacent in the circumferential direction, are defined as S2, S3, ..., Sn in sequence, S1 to Sn satisfy formula (10).

[0136] Sn≤Sn-1≤...≤S1 (10)

[0137] According to the rotating electric machine 100 of embodiment 2, the following rotating electric machine 100 can be provided: when a key portion 22 is provided on the inner circumference of the rotor core 2 and stress relief grooves 23 are provided at both ends of the key portion 22, by making the positions and shapes of the balancing holes 31H, 32H, 33H, and 34H provided between the magnetic poles non-uniform, the contact area between the rotor core 2 and the shaft 4 can be ensured and the separation of the two can be prevented, and the deformation imbalance and stress imbalance of the rotor core 2 caused by the key portion 22 and the stress relief groove 23 can be effectively suppressed, thereby improving durability.

[0138] The present application describes various illustrative embodiments and examples, but the various features, methods, and functions described in one or more embodiments are not limited to the application of specific embodiments and can be applied to the embodiments alone or in various combinations.

[0139] Therefore, numerous modifications not shown in the examples are conceivable within the scope of the technology disclosed in the present specification, including, for example, modification, addition or omission of at least one component, and extraction of at least one component and combination with components of other embodiments.

[0140] Description of Reference Numerals

[0141] 1 rotor, 2 rotor core, 3 permanent magnet, 4 shaft, 5 stator core, 6 coil, 7 stator, 8 starting point, 10 deformation line, 11 original shape line, 21 magnet insertion hole, 22 key portion, 23 stress relief groove, 221 key side, 23R1 first arc, 23R2 second arc, 24 balancing groove, 26d cross-sectional area, 31 balancing hole, 31H, 32H, 33H, 34H balancing hole, 311L first balancing hole center line, 312L second balancing hole center line, 313L third balancing hole center line, 314L fourth balancing hole center line, 271 peripheral bridging portion, 271B-276B peripheral bridging portion, 41 key slot portion, 100 rotating motor.

Claims

1. A rotating electrical machine, characterized in that: The rotating electrical machine comprises: stator; and A rotor, the rotor comprising a rotor core, a key portion, a stress relief groove and a plurality of balancing holes, the rotor core being arranged on the inner side of the stator, the key portion being formed by radially protruding from the inner circumference of the rotor core and being arranged at two locations facing each other at 180 degrees, the stress relief groove being arranged at both ends of the key portion and being recessed radially outward from the inner circumference of the rotor core, the plurality of balancing holes being respectively arranged between the plurality of magnetic poles of the rotor core, The length from the center of the balancing hole arranged on the first straight line to the center of the rotor core is smaller than the length from the center of the rotor core to the center of the balancing hole arranged on a straight line that intersects the first straight line perpendicularly, and the first straight line passes through the center of the rotor core and the center of the key portion.

2. The rotating electrical machine according to claim 1, characterized in that The first straight line starting from the center of the rotor core and ending at the center of the balancing hole on a half straight line passing through the center of the key portion is defined as d1. The nth straight line starting from the center of the rotor core and ending at the center of the balancing hole on a half straight line perpendicularly intersecting the first straight line is defined as dn, where the natural number n>1, Taking the center of the rotor core as the starting point, straight lines to the center of the balancing holes between the plurality of magnetic poles sandwiched by the balancing holes on the first straight line and the balancing holes on the nth straight line in the circumferential direction are defined as d2, d3, ..., dn-1 in the order of being close to the balancing holes on the first straight line, d1 to dn satisfy dn≥dn-1≥...≥d1 and dn>d1.

3. The rotating electrical machine according to claim 2, characterized in that When the area of ​​the balancing hole on the first straight line is defined as S1, the area of ​​the balancing hole on the nth straight line is defined as Sn, and the areas of the balancing holes between the plurality of magnetic poles sandwiched by the balancing holes on the first straight line and the balancing holes on the nth straight line in the circumferential direction are defined as S2, S3, ..., Sn-1 in the order of being close to the balancing holes on the first straight line, S1 to Sn satisfy Sn≤Sn-1≤...≤S1.

4. The rotating electrical machine according to any one of claims 1 to 3, characterized in that: A plurality of permanent magnets are embedded in the rotor core. Two permanent magnets are arranged in a V-shape at one magnetic pole.

5. The rotating electrical machine according to any one of claims 1 to 3, characterized in that: The rotor core is provided with a shaft that is fitted by press-fitting.

6. The rotating electrical machine according to claim 4, characterized in that The rotor core is provided with a shaft that is fitted by press-fitting.

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