Rotary electric machine

Abstract

To provide a rotary electric machine capable of suppressing not only vibration and noise of a stator core due to electromagnetic force but also vibration and noise of the stator core due to magnetostriction.MEANS FOR SOLVING THE PROBLEM: In a yoke part 12 of a stator core 11 in a rotary electric machine 1, a plurality of slit groups 15 each consisting of a plurality of slits 16,17 extending in the circumferential direction of the stator core 11 are formed in the same number as the number of poles along the circumferential direction of the stator core 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating electric machine, and more particularly to a rotating electric machine capable of suppressing vibration and noise. [Background technology]

[0002] Generally, in a rotating electric machine, the stator is a stationary part that plays a role in generating the force for rotation, and is mainly composed of windings through which current flows and a stator core that is a magnetic path.

[0003] The stator core is an iron core made of laminated magnetic steel sheets, and vibration and noise caused by electromagnetic forces in the air gap between the stator core and the rotor, which is a rotating part, can easily become a problem. In addition to the electromagnetic forces, vibration and noise in the stator core can also be caused by magnetostriction, which occurs when the magnetic steel sheets expand and contract due to magnetic flux that interlinks with the stator core.

[0004] BACKGROUND ART Conventionally, as a rotating electric machine capable of suppressing vibration and noise, for example, the rotating electric machine disclosed in Patent Document 1 has been proposed. In the rotating electric machine disclosed in Patent Document 1, the stator core includes a first stator core having first slits formed on the outer periphery so as to extend in the radial direction, and a second stator core having second slits formed on the outer periphery so as to extend in the radial direction. The first stator core and the second stator core are stacked alternately in the axial direction of the rotor such that the circumferential positions of the first slits differ from the circumferential positions of the second slits.

[0005] According to the rotating electric machine shown in Patent Document 1, the stator core is constructed by stacking the first stator core and the second stator core so that the circumferential positions of the first slits and the second slits are different, so that frictional damping occurs between the first stator core and the second stator core, and vibration and noise of the entire stator core can be suppressed without causing a decrease in performance or an increase in volume or weight. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-348557 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional rotating electric machine disclosed in Patent Document 1 has the following problems.

[0008] In the rotating electric machine disclosed in Patent Document 1, the first stator core and the second stator core are laminated so that the first slits extending radially and the second slits extending radially are positioned at different circumferential positions. This configuration suppresses vibration and noise of the stator core due to electromagnetic forces generated in the air gap between the stator core and the rotor, which is a rotating component. However, it does not suppress vibration and noise of the stator core due to magnetostriction caused by expansion and contraction of the electromagnetic steel sheets due to magnetic flux linking the stator core. The reason for this is that when the rotor rotates and magnetic flux linkages the stator core, radial magnetic flux is generated in the stator core, and this radial magnetic flux causes radial magnetostriction. If radial slits are provided in the stator core, the magnetic resistance of the slits is small, so the radial magnetic flux density does not decrease, and radial magnetostriction cannot be reduced.

[0009] Therefore, the present invention has been made to solve this conventional problem, and its object is to provide a rotating electric machine that can appropriately suppress vibration and noise of the stator core caused by magnetostriction. [Means for solving the problem]

[0010] In order to achieve the above object, one aspect of the present invention provides a rotating electric machine comprising a stator consisting of a cylindrical stator core having a yoke portion provided on the outer periphery and teeth portions provided inside the yoke portion, and a rotor arranged freely rotatably on the inner periphery of the stator core via an air gap, wherein a plurality of slit groups each consisting of a plurality of slits extending in the circumferential direction of the stator core are formed in the yoke portion of the stator core along the circumferential direction of the stator core, the number of slit groups being the same as the number of poles. [Effects of the Invention]

[0011] According to the rotating electric machine of the present invention, it is possible to provide a rotating electric machine that can appropriately suppress vibration and noise of the stator core caused by magnetostriction. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a rotating electric machine according to an embodiment of the present invention; [Figure 2] 2 is an enlarged cross-sectional view showing the vicinity of a group of slits in the rotating electric machine shown in FIG. 1. [Figure 3] 2 is an exploded perspective view showing the lamination state of the first, second, and third layers of electromagnetic steel sheets of the stator core in the rotating electric machine shown in FIG. 1. FIG. [Figure 4] 2 is a cross-sectional view of the rotating electric machine shown in FIG. 1 taken at the location of a first layer of electromagnetic steel sheets. [Figure 5] 2 is a cross-sectional view of the rotating electric machine shown in FIG. 1, taken at the second layer of electromagnetic steel sheets. [Figure 6] 2 is a diagram for explaining the state of magnetic flux when it interlinks with a yoke portion from a tooth portion in the rotating electric machine shown in FIG. 1. FIG. [Figure 7] FIG. 7 is an enlarged view showing the vicinity of the slit group in FIG. 6. [Figure 8] 2 is a diagram for explaining the state of magnetostriction when magnetic flux interlinks from a tooth portion to a yoke portion in the rotating electric machine shown in FIG. 1. FIG. [Figure 9]10A and 10B are diagrams for explaining the state of magnetic flux when the magnetic flux is linked from the teeth portion to the yoke portion in the rotating electric machine according to the reference example. [Figure 10] FIG. 10 is an enlarged view of the vicinity of the slit in FIG. 9. [Figure 11] 10A and 10B are diagrams for explaining the state of magnetostriction when magnetic flux interlinks from a tooth portion to a yoke portion in a rotating electric machine according to a reference example. [Figure 12] FIG. 10 is a diagram showing flux lines in a stator core of a rotating electric machine according to an embodiment of the present invention. [Figure 13] 13 is an enlarged view of a portion indicated by an arrow A in FIG. 12. FIG. [Figure 14] FIG. 10 is a diagram showing flux lines in a stator core of a rotating electric machine of a comparative example. [Figure 15] 15 is an enlarged view of a portion indicated by an arrow B in FIG. 14. FIG. [Figure 16] 10 is a graph showing a comparison of the relationship between the magnetic flux density in the radial direction of the stator core and the electrical angle at evaluation point a near the slit group of an example of the present invention and the slit of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiment described below is an example of a rotating electric machine, and exemplifies a device for embodying the technical concept of the present invention. However, the technical concept of the present invention is not limited to the following embodiment in terms of the materials, shapes, structures, arrangements, etc. of the components.

[0014] In addition, the drawings are schematic, and therefore it should be noted that the relationship between thickness and planar dimensions, ratios, etc. may differ from the actual relationship, and the drawings may also contain parts where the relationship and ratio of dimensions differ from each other.

[0015] FIG. 1 shows a schematic configuration of a rotating electrical machine according to one embodiment of the present invention. The rotating electric machine 1 shown in Figure 1 is a six-pole embedded magnet synchronous motor, and includes a stator 10 and a rotor 20 rotatably arranged on the inner circumferential side of a stator core 11 of the stator 10 via an air gap G.

[0016] Here, the stator 10 has a cylindrical stator core 11. The stator core 11 has a yoke portion 12 provided on the outer periphery and a plurality of teeth 13 provided along the circumferential direction inside the yoke portion 12. Slots 14 are formed on both sides of the circumference of each tooth portion 13. A plurality of armature windings (not shown) are wound around each tooth portion 13.

[0017] Furthermore, in the yoke portion 12 of the stator core 11, a plurality of slit groups 15, each consisting of a set of three slits 16, 17 extending in the circumferential direction of the stator core 11, are formed in the same number (six) as the number of poles (six poles) along the circumferential direction of the stator core 11. The formation intervals of the plurality of slit groups 15 in the circumferential direction are intervals obtained by dividing 360° by the number of poles, and in this embodiment, the slit groups are formed at intervals of 60°, which is 360° divided by 6.

[0018] In this way, in the yoke portion 12 of the stator core 11, a plurality of slit groups 15 each consisting of a set of three slits 16, 17 extending in the circumferential direction of the stator core 11 are formed. As will be described later, when the rotor 20 rotates and the magnetic flux F (see FIGS. 6 and 7) interlinks with the stator core 11, the radial magnetic flux F R becomes smaller due to the magnetic resistance of each slit group 15, and the magnetic flux density in the radial direction decreases, so the magnetostriction M R (see FIG. 8) is also reduced, making it possible to appropriately suppress vibration and noise in the stator core 11. Furthermore, it is also possible to suppress vibration and noise in the stator core 11 caused by electromagnetic force.

[0019] In addition, by forming a plurality of slit groups 15 in the same number as the number of poles along the circumferential direction of the stator core 11, the radial magnetic flux F generated when the rotor 20 rotates and the magnetic flux F interlinks with the stator core 11 can be reduced. RThe radial magnetic flux F at the electrical angle where is the largest (see Figure 16) R can be reduced to reduce the magnetic flux density in the radial direction.

[0020] 2, each of the three slits 16, 17 constituting the plurality of (six) slit groups 15 is composed of an inner slit 16 extending in the circumferential direction and disposed radially inside the yoke portion 12, and two outer slits 17 extending in the circumferential direction and disposed at a predetermined interval from each other radially outside the yoke portion 12. The inner slit 16 is formed at a position corresponding to the space between the two outer slits 17 in the circumferential direction of the stator core 11 and corresponding to the radial outside of the teeth portion 13.

[0021] Here, in the set of three slits 16, 17 that make up each slit group 15, if there is one outer slit 17 and two inner slits 16, and the inside and outside are configured in the reverse order to the above, the radial magnetic flux F generated when linking the stator core 11 will R However, it is difficult to reduce the magnetic resistance due to the slit groups 15.

[0022] Furthermore, the width w of the inner slit 16 is the same as the width w of each of the two outer slits 17, and the width w is equal to or less than the size of the air gap G. This is because if the width w of each of the inner slit 16 and the two outer slits 17 is larger than the size of the air gap G, the performance of the rotating electric machine 1, such as the rotational torque, will be reduced.

[0023] Furthermore, the circumferential length l1 of the inner slit 16 satisfies the relationship t1≦l1≦2t1, where t1 is the circumferential length of the umbrella portion 13a provided at the tip of the tooth portion 13. If l1 is less than t1, the radial magnetic flux F R On the other hand, if l1 is greater than t1, the performance of the rotating electrical machine 1, such as the rotational torque, is affected, so the upper limit of l1 is set to 2t1.

[0024] Also, the circumferential length l2 of each of the two outer slits 17 is the same, and t1 < l2 ≤ l1. If l2 is greater than l1, the influence on the performance such as the rotational torque of the rotating electrical machine 1 is significant. On the other hand, if l2 is less than t1, the decrease amount of the radial magnetic flux F R becomes small.

[0025] Also, the distance d1 from the radial center line CL of the yoke portion 12 to each of the two outer slits 17 and the inner slit 16 is the same. When the radial width of the yoke portion 12 is b1, d1 = 1 / 6b1. If d1 is less than 1 / 6b1, the magnetic flux density becomes locally high. On the other hand, if d1 is greater than 1 / 6b1, the decrease amount of the radial magnetic flux F R becomes small. Here, as shown in FIG. 2, the radial width b1 of the yoke portion 12 is the smallest distance between the outer peripheral surface of the yoke portion 12 and the outermost edge portion in the radial direction of the slot 14.

[0026] Also, the predetermined interval d2 between the two outer slits 17 is d2 = t1. If d2 is less than t1, the magnetic flux density becomes too locally high. On the other hand, if d2 is greater than t1, the decrease amount of the radial magnetic flux F R becomes small.

[0027] 3, the stator core 11 is formed by, for example, stacking a plurality of (three in this embodiment) electromagnetic steel sheets 111, 112, 113 in the axial direction of the rotor 20. When stacking these electromagnetic steel sheets 111, 112, 113, the plurality of electromagnetic steel sheets 111, 112, 113 are stacked in the axial direction such that the circumferential positions of the plurality of slit groups 15 formed in each of the axially adjacent electromagnetic steel sheets 111, 112; 112, 113 are different. 3 , 4 , and 5 , the circumferential positions of the multiple slit groups 15 formed in axially adjacent first-layer electromagnetic steel sheets 111 are different from the circumferential positions of the multiple slit groups 15 formed in the second-layer electromagnetic steel sheets 112, and the circumferential positions of the multiple slit groups 15 formed in the second-layer electromagnetic steel sheets 112 are shifted counterclockwise by 30° with respect to the circumferential positions of the multiple slit groups 15 formed in the first-layer electromagnetic steel sheets 111. Furthermore, the circumferential positions of the multiple slit groups 15 formed in axially adjacent second-layer electromagnetic steel sheets 112 are different from the circumferential positions of the multiple slit groups 15 formed in the third-layer electromagnetic steel sheets 113, and the circumferential positions of the multiple slit groups 15 formed in the third-layer electromagnetic steel sheets 113 are shifted clockwise by 30° with respect to the circumferential positions of the multiple slit groups 15 formed in the second-layer electromagnetic steel sheets 112. Therefore, in this embodiment, the circumferential positions of the multiple slit groups 15 formed in the first layer of electromagnetic steel sheet 111 are the same as the circumferential positions of the multiple slit groups 15 formed in the third layer of electromagnetic steel sheet 113.

[0028] In this way, the stator core 11 is formed by stacking a plurality of electromagnetic steel sheets 111, 112, 113 in the axial direction so that the circumferential positions of the plurality of slit groups 15 formed in each of the axially adjacent electromagnetic steel sheets 111, 112; 112, 113 are different.

[0029] This allows vibrations and noise from the stator core 11 to be dispersed in the axial direction. The rotor 20 also includes a cylindrical rotor core 21 formed around an axial hole 22, and six magnetic poles 24 provided on the rotor core 21. The air gap G described above is formed between the outer peripheral surface 21a of the rotor core 21 and the inner peripheral surface 11a of the stator core 11. The rotor core 21 is made up of a laminated core. A rotating shaft 23 is inserted and fixed into the axial hole 22 of the rotor core 21, and the rotor 20 rotates by the rotating shaft 23. Each of the six magnetic poles 24 is formed by a pair of permanent magnets 25 fixed to the rotor core 21.

[0030] Next, in the rotating electric machine 1 shown in FIG. 1, the state of magnetic flux and magnetostriction when the rotor 20 rotates and the magnetic flux F interlinks with the yoke portion 12 from the teeth portion 13 will be described with reference to FIGS.

[0031] As shown in Fig. 6, when the rotor 20 rotates, the magnetic flux F is linked from the teeth 13 to the yoke 12. At this time, the magnetic flux F is a large circumferential magnetic flux F due to the magnetic resistance of the slit group 15 in the yoke 12 as shown in Figs. c and a small radial magnetic flux F R When this magnetic flux F interlinks with the stator core 11, a radial magnetic flux F R However, due to the magnetic resistance of each slit group 15, the radial magnetic flux F R (See Fig. 9) is smaller than that, so the magnetic flux density in the radial direction decreases, and the magnetostriction in the radial direction M R (See FIG. 8) shows the radial magnetostriction M R (see FIG. 11), vibration and noise in the stator core 11 can be suppressed. In the radial direction of the yoke portion 12, as shown in FIG. c This results in a relatively large magnetostriction M c is occurring.

[0032] In contrast, the state of magnetic flux and magnetostriction when the rotor rotates and the magnetic flux interlinks from the teeth to the yoke in a rotating electric machine according to a reference example will be described with reference to Figs. 9 to 11. Fig. 9 is a diagram for explaining the state of magnetic flux when the magnetic flux interlinks from the teeth to the yoke in a rotating electric machine according to a reference example. Fig. 10 is an enlarged view of the vicinity of the slit in Fig. 9. Fig. 11 is a diagram for explaining the state of magnetostriction when the magnetic flux interlinks from the teeth to the yoke in a rotating electric machine according to a reference example.

[0033] First, the rotating electric machine 101 according to the reference example shown in FIG. 9 has the same basic configuration as the rotating electric machine 1 shown in FIG. 6, and is a six-pole embedded magnet synchronous motor, and includes a stator 110 and a rotor 120 that is rotatably arranged on the inner circumferential side of the stator core 111 of the stator 110 via an air gap G.

[0034] The stator 110 includes a cylindrical stator core 111. The stator core 111 includes a yoke portion 112 provided on the outer periphery and a plurality of teeth 113 provided circumferentially inside the yoke portion 112. An umbrella portion 113a is provided at the tip of each tooth 113. Slots 114 are formed on both circumferential sides of each tooth 113. A plurality of armature windings (not shown) are wound around each tooth 113. The rotor 120 includes a cylindrical rotor core 121 formed around an axial hole and six magnetic poles 124 provided on the rotor core 121. A rotating shaft 123 is inserted and fixed into the axial hole of the rotor core 121, and the rotor 120 rotates around the rotating shaft 123. Each of the six magnetic poles 124 is formed by a pair of permanent magnets 125 fixed to the rotor core 121.

[0035] Here, similar to the rotating electric machine 1 shown in Fig. 6, a plurality of slits are formed in the rotating electric machine 101 according to the reference example shown in Fig. 9, but the manner in which the slits are formed is different. That is, a plurality of slits 115 (12 in this reference example) extending radially from the outer circumferential surface are formed in the yoke portion 112 of the stator core 111. The slits 115 are formed at 30° intervals in the circumferential direction.

[0036] 9, when the rotor 120 rotates, the magnetic flux F is linked from the teeth 113 to the yoke 112. At this time, the magnetic flux F is circumferentially directed to the yoke 112 by the magnetic resistance of the slits 115 as shown in FIGS. c and the radial magnetic flux F R When this magnetic flux F interlinks with the stator core 11, a radial magnetic flux F R Since each slit 115 extends in the radial direction and the magnetic resistance of each slit 115 is small, the radial magnetic flux F R (See Fig. 6) and the magnetic flux density in the radial direction is also large. Therefore, the magnetostriction in the radial direction M R (See FIG. 11) also shows the radial magnetostriction M R (see FIG. 8), and therefore vibration and noise in the stator core 11 cannot be suppressed. In addition, as shown in FIG. 11, in the radial direction of the yoke portion 112, the magnetic flux F c Magnetostriction M c is occurring.

[0037] 1 of this embodiment, a plurality of slit groups 15, each consisting of a set of three slits 16, 17 extending in the circumferential direction of the stator core 11, are formed in the yoke portion 12 of the stator core 11 along the circumferential direction of the stator core 11, the number of which is the same as the number of poles. As a result, when the rotor 20 rotates and the magnetic flux F interlinks with the stator core 11, the radial magnetic flux F R becomes smaller due to the magnetic resistance of each slit group 15, and the magnetic flux density in the radial direction decreases, so the magnetostriction M RThis also reduces the vibration and noise of the stator core 11, thereby making it possible to appropriately suppress vibration and noise in the stator core 11. Furthermore, it is possible to suppress vibration and noise in the stator core 11 caused by electromagnetic force.

[0038] By forming a plurality of slit groups 15 in the same number as the number of poles along the circumferential direction of the stator core 11, the radial magnetic flux F generated when the rotor 20 rotates and the magnetic flux F interlinks with the stator core 11 can be reduced. R The radial magnetic flux F at the electrical angle where is the largest (see Figure 16) R can be reduced to reduce the magnetic flux density in the radial direction.

[0039] Furthermore, in the rotating electric machine 1 according to this embodiment, each of the three slits 16, 17 constituting the plurality of slit groups 15 is composed of an inner slit 16 extending in the circumferential direction and disposed radially inside the yoke portion 12, and two outer slits 17 extending in the circumferential direction and disposed radially outside the yoke portion 12 at a predetermined circumferential interval d2. The inner slit 16 is formed at a position corresponding to the space between the two outer slits 17 in the circumferential direction of the stator core 11 and corresponding to the radial outside of the tooth portions 13.

[0040] This reduces the effect on the performance of the rotational torque of the rotor 20, and also reduces the radial magnetic flux F generated when linking the stator core 11. R can be appropriately reduced by the magnetic resistance of each slit group 15.

[0041] Furthermore, according to the rotating electric machine 1 of this embodiment, the stator core 11 is formed by stacking a plurality of electromagnetic steel plates 111, 112, 113 in the axial direction so that the circumferential positions of a plurality of slit groups 15 formed in each of the electromagnetic steel plates 111, 112; 112, 113 adjacent to each other in the axial direction of the rotor 20 are different.

[0042] This allows vibrations and noise from the stator core 11 to be dispersed in the axial direction. As described above, the embodiments of the present invention have been explained, but the present invention is not limited to this, and various changes and improvements can be made. For example, the number of poles of the rotating electrical machine 1 is not limited to 6 poles, and can be any number of poles. The number of the slit groups 15 formed in the yoke portion 12 of the stator core 11 is the same as the number of poles.

[0043] Also, each of the plurality of slit groups 15 is composed of a set of three slits 16 and 17, but it is not limited to a set of three, and may be composed of a plurality (two or more) of slits. Even in this case, when the rotor 20 rotates and the magnetic flux F intersects the stator core 11, the radial magnetic flux F R is reduced by the magnetic resistance of each slit group 15, and the radial magnetic flux density decreases, so the radial magnetic strain M R also decreases, and the vibration and noise in the stator core 11 can be appropriately suppressed. Also, the vibration and noise of the stator core 11 due to electromagnetic force can be suppressed.

[0044] Also, the set of three slits 16 and 17 constituting each of the plurality of slit groups 15 is not limited to the case where it consists of an inner slit 16 extending in the circumferential direction arranged inside the yoke portion 12 in the radial direction and two outer slits 17 extending in the circumferential direction arranged outside the yoke portion 12 in the radial direction with a predetermined interval d2 in the circumferential direction.

[0045] Also, the width w of the inner slit 16 is not necessarily less than or equal to the size of the air gap G, the circumferential length l1 of the inner slit 16 is t1≦l1≦2t1, the circumferential length l2 of each of the two outer slits 17 is t1<l2≦l1, the distance d1 of each of the two outer slits 17 and the inner slit 16 from the center line CL in the radial direction of the yoke portion 12 is d1 = 1 / 6b1, and the predetermined interval d2 between the two outer slits 17 is not necessarily d2 = t1.

[0046] Furthermore, the stator core 11 is not limited to being formed by stacking a plurality of electromagnetic steel sheets 111, 112, 113 in the axial direction such that the circumferential positions of the plurality of slit groups 15 formed in each of the electromagnetic steel sheets 111, 112; 112, 113 adjacent in the axial direction of the rotor 20 differ. For example, the stator core 11 may be formed by stacking a plurality of electromagnetic steel sheets in the axial direction such that the circumferential positions of the plurality of slit groups 15 formed in a predetermined number of electromagnetic steel sheets in the axial direction of the rotor 20 differ from the circumferential positions of the plurality of slit groups 15 formed in a predetermined number of electromagnetic steel sheets subsequent to the predetermined number of electromagnetic steel sheets in the axial direction of the rotor 20. [Example]

[0047] In order to verify the effect of the present invention, the magnitude of the magnetic flux density in the radial direction of the stator core of the present invention example and the magnitude of the magnetic flux density in the radial direction of the stator core of the comparative example were investigated. The example of the present invention has the configuration of a rotating electric machine 1 shown in FIGS. 1 to 8, and the comparative example has the configuration of a rotating electric machine 101 shown in FIGS. FIG. 12 shows flux lines (magnetic flux lines) in the stator core 11 of the rotating electric machine 1 according to the present invention, and FIG. 13 shows an enlarged view of the portion indicated by arrow A in FIG.

[0048] On the other hand, FIG. 14 shows flux lines (magnetic flux lines) in stator core 11 of rotating electric machine 101 of the comparative example, and FIG. 15 shows an enlarged view of the portion indicated by arrow B in FIG.

[0049] FIG. 16 also shows a comparison of the relationship between the magnetic flux density in the radial direction of the stator core and the electrical angle at evaluation point a near slit group 15 of the present invention and slit 115 of the comparative example.

[0050] In the comparative example, as shown in FIGS. 14 and 15, when the rotor 120 rotates, a radial magnetic flux F LAs shown in Fig. 16, the radial magnetic flux density at evaluation point a near slit 115 is greatest at 1.25 [T] near electrical angles of 135° and 315°. This large magnetic flux density causes large magnetostriction, which generates radial vibration in rotating electric machine 101 that is likely to become noise.

[0051] On the other hand, in the case of the example of the present invention, as shown in FIGS. 12 and 13, when the rotor 20 rotates, a radial magnetic flux F L However, as shown in FIG. 16 , the radial magnetic flux density at evaluation point a near slit group 15 is small near 0 [T] at any electrical angle between 0° and 360°, reaching a maximum of 0.25 [T], which is a reduction of about 1 [T], or about 1 / 5, compared to the comparative example. In this way, the radial magnetic flux density at evaluation point a is reduced in the example of the present invention because the radial magnetic flux generated when the magnetic flux interlinks with the stator core 11 is reduced by the magnetic resistance of slit group 15. As a result of the reduction in radial magnetic flux density, magnetostriction in the same direction is also reduced, and it was confirmed that radial vibration can be suppressed. [Explanation of symbols]

[0052] 1 Rotating electric machine 10 Stator 11 Stator core 11a Inner surface 111 First layer of electrical steel sheet 112 Second layer of electromagnetic steel sheet 113 Third layer of electromagnetic steel sheet 12 Yoke 13 Teeth 13a Umbrella Club 14 slots 15 Slit Group 16 Inner slit (slit) 17 Outer slit (slit) 20 rotor 21 Rotor core 21a Outer surface 22 Shaft hole 23 Rotation axis 24 magnetic poles 25 Permanent Magnets G Air gap

Claims

1. A rotating electric machine comprising: a stator made of a cylindrical stator core having a yoke portion provided on an outer periphery thereof and teeth portions provided inside the yoke portion; and a rotor rotatably disposed on an inner periphery of the stator core of the stator via an air gap, A rotating electric machine characterized in that a plurality of slit groups, each consisting of a plurality of slits extending in the circumferential direction of the stator core, are formed in the yoke portion of the stator core along the circumferential direction of the stator core, the number of slit groups being the same as the number of poles.

2. The rotating electric machine described in claim 1, characterized in that each of the multiple slit groups is composed of a set of three slits, and comprises an inner slit extending in the circumferential direction and positioned radially inside the yoke portion, and two outer slits extending in the circumferential direction and positioned radially outside the yoke portion at a predetermined circumferential interval, and the inner slit is formed at a position corresponding to between the two outer slits in the circumferential direction of the stator core and corresponding to the radial outside of the tooth portion.

3. The width w of each of the two outer slits and the inner slit is equal to or less than the size of the air gap, and the circumferential length l of the inner slit １ is the circumferential length of the umbrella portion provided at the tip of the tooth portion, １ In this case, t １ ≦l １ ≦2t １ and the circumferential length l of each of the two outer slits ２ is t １ <l ２ ≦l １ and the distance d from the radial center line of the yoke portion to each of the two outer slits and the inner slit is １ is the radial width of the yoke portion, b １ In this case, d １ = 1 / 6b １ and the predetermined distance d between the two outer slits is ２ is d ２ = t １ 3. The rotating electric machine according to claim 2, wherein:

4. 4. The rotating electric machine according to claim 1, wherein the stator core is stacked in the axial direction of the rotor such that the circumferential positions of the plurality of slit groups formed in each of the electromagnetic steel plates adjacent to each other in the axial direction of the rotor are different.

5. A rotating electric machine according to any one of claims 1 to 3, characterized in that the stator core is stacked in the axial direction so that the circumferential positions of the groups of slits formed in a predetermined number of electromagnetic steel plates in the axial direction of the rotor are different from the circumferential positions of the groups of slits formed in a predetermined number of electromagnetic steel plates subsequent to the predetermined number of electromagnetic steel plates in the axial direction of the rotor.

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