WO2024157305A1

WO2024157305A1 - Stator, electric motor, compressor, and refrigeration cycle apparatus

Info

Publication number: WO2024157305A1
Application number: PCT/JP2023/001823
Authority: WO
Inventors: 優樹東
Original assignee: 三菱電機株式会社
Priority date: 2023-01-23
Filing date: 2023-01-23
Publication date: 2024-08-02

Abstract

This stator core has an annular core back, teeth extending from the core back to the radially inner side, and slots adjacent to the tooth in the circumferential direction. A winding is wound around the tooth with an insulating portion interposed therebetween. The tooth has an end surface that defines an end portion of the tooth in the axial direction, side surfaces that face the slots, stepped portions each formed between the end surface and the side surface, and an intermediate stepped portion formed in each stepped portion. When the dimension of the tooth in the direction orthogonal to both the axial direction and the extending direction of the tooth is defined as the width, the tooth has widths W1, W2, W3 depending on positions in the axial direction and W1>W2>W3 is satisfied. The insulating portion has a first surface that covers the end surface of the tooth, a second surface that faces the slots, and a third surface that is a curved surface or a sloped surface that extends from the first surface to the second surface. The minimum distance T1 from the end surface of the tooth to the first surface of the insulating portion and the minimum distance T3 from the intermediate stepped portion to the third surface of the insulating portion satisfy T1>T3.

Description

Stator, motor, compressor and refrigeration cycle device

This disclosure relates to a stator, an electric motor, a compressor, and a refrigeration cycle device.

The stator of an electric motor has a stator core with teeth, windings wound around the teeth, and insulating parts interposed between the teeth and the windings. In order to shorten the circumferential length of the windings and reduce copper loss, it is desirable to reduce the swelling of the windings. Therefore, it has been proposed to provide a step part at the axial end of the teeth (for example, Patent Document 1).

JP 2011-112205 A (see Abstract)

However, providing a step on the teeth locally reduces the cross-sectional area of the teeth. This can cause magnetic saturation within the teeth, increasing iron loss.

This disclosure has been made to solve the above problems, and aims to shorten the perimeter of the winding and suppress the increase in iron loss.

The stator according to the present disclosure has a stator core having an annular core back, teeth extending radially inward from the core back, and slots adjacent to the teeth in the circumferential direction of the core back, an insulating portion provided on the teeth, and a winding wound around the teeth via the insulating portion. The teeth have end faces that define the ends of the teeth in the axial direction of the stator core, side faces the slot, a step portion formed between the end face and the side face, and an intermediate step portion formed in the step portion. If the dimension of the teeth in a direction perpendicular to both the axial direction and the extension direction of the teeth is defined as the width, the teeth have widths W1, W2, and W3 depending on the position in the axial direction, and W1>W2>W3 holds. The insulating portion has a first surface that covers the end face of the teeth, a second surface that faces the slot, and a third surface that is a curved surface or an inclined surface extending from the first surface to the second surface. The shortest distance T1 from the end face of the tooth to the first surface of the insulating portion and the shortest distance T3 from the intermediate step to the third surface of the insulating portion satisfy T1>T3.

In the present disclosure, an intermediate step is provided at the step portion of the teeth, and the strength of the insulating portion is ensured by the above-mentioned relationship T1>T3, so the cross-sectional area of the teeth can be increased while suppressing the swelling of the winding. This makes it possible to shorten the circumference of the winding and suppress the increase in iron loss.

1 is a cross-sectional view showing an electric motor according to a first embodiment of the present invention; 2 is a diagram showing the axial positional relationship between a stator core and a rotor core in the first embodiment. FIG. FIG. 2 is a plan view showing the stator core of the first embodiment. FIG. 2 is a perspective view showing a split core according to the first embodiment. 2 is a perspective view showing a split core and an insulating portion according to the first embodiment. FIG. 4 is a cross-sectional view showing a tooth and an insulating portion according to the first embodiment. FIG. 4 is an enlarged cross-sectional view showing a portion including a step portion of the tooth according to the first embodiment. FIG. 4A is a cross-sectional view showing the teeth and insulating portion of Comparative Example 1, FIG. 4B is a cross-sectional view showing the teeth and insulating portion of Comparative Example 2, and FIG. 4C is a cross-sectional view showing the teeth and insulating portion of Comparative Example 3. 13 is an enlarged view showing a portion including a step portion of a tooth of Comparative Example 3. FIG. 4 is a cross-sectional view for explaining the operation of the first embodiment. FIG. 4 is a cross-sectional view showing dimensions of each part including a step part of the tooth of the first embodiment. FIG. 5A to 5E show examples of shapes of step portions of teeth according to the first embodiment. 5A and 5B are diagrams showing the relationship between the shape of the step portion of the teeth and the winding bulge state of the winding in the first embodiment. 13 is a graph showing the relationship between loss and the ratio A/L1 of the height A of the step portion to the length L1 of the teeth in Comparative Example 3. 11 is a graph showing the relationship between loss and a ratio A/L1 of a height A of a step portion to a length L1 of a tooth in the first embodiment. 5A and 5B show examples of the shapes of step portions and intermediate step portions of teeth in a numerical analysis of the first embodiment. 13A and 13B are cross-sectional views showing a case in which the cross-sectional area of the intermediate step portion is maximized. 11 is a cross-sectional view showing a portion including a step portion of a tooth according to a second embodiment. FIG. 13 is a cross-sectional view showing the shape of a step portion and an intermediate step portion of a tooth according to a second embodiment. FIG. 13 is a diagram showing the axial positional relationship between a stator core and a rotor core in a third embodiment. FIG. 13 is a diagram showing the axial positional relationship between a stator core and a rotor core in a modified example of the third embodiment. FIG. FIG. 13 is a perspective view showing a split core and an insulator according to a fourth embodiment. A cross-sectional view showing the teeth, insulator, and insulating film of embodiment 4. A cross-sectional view showing a tooth, an insulator, an insulating film, and a winding in a modified example of the fourth embodiment. 13A to 13C are cross-sectional views showing a portion including a step portion of a tooth in modified examples of each embodiment. FIG. 2 is a vertical sectional view showing a compressor to which the electric motor of each embodiment can be applied. FIG. 27 is a diagram showing a refrigeration cycle device to which the compressor of FIG. 26 can be applied.

Embodiment 1.
<Motor configuration>
First, a description will be given of embodiment 1. Fig. 1 is a cross-sectional view showing an electric motor 100 according to embodiment 1. The electric motor 100 shown in Fig. 1 is an embedded permanent magnet electric motor, and is used in, for example, a compressor 8 (Fig. 26).

The electric motor 100 has a rotor 5 having a shaft 90 which is a rotating shaft, and a stator 1 arranged to surround the rotor 5. An air gap of, for example, 0.3 to 1.0 mm is provided between the stator 1 and the rotor 5. The stator 1 is incorporated inside the cylindrical shell 80 of the compressor 8 (Figure 26) which will be described later.

In the following, the direction of the axis Ax, which is the center of rotation of the rotor 5, is referred to as the "axial direction". The radial direction centered on the axis Ax is referred to as the "radial direction". The circumferential direction centered on the axis Ax is referred to as the "circumferential direction".

<Rotor configuration>
The rotor 5 has a cylindrical rotor core 50 centered on the axis Ax, and a permanent magnet 60 attached to the rotor core 50. The rotor core 50 is made by stacking a plurality of electromagnetic steel plates in the axial direction and fixing them by caulking, etc. The thickness of the electromagnetic steel plates is 0.1 to 0.7 mm.

A central hole 53 is formed in the radial center of the rotor core 50. The shaft 90 is fixed in the central hole 53 of the rotor core 50 by shrink fitting, press fitting, adhesive, or the like. The rotor core 50 has a circular outer periphery centered on the axis Ax.

A number of magnet insertion holes 51 are formed along the outer periphery of the rotor core 50. One magnet insertion hole 51 corresponds to one magnetic pole. The circumferential center of the magnet insertion hole 51 corresponds to the pole center. An inter-pole portion is defined between adjacent magnet insertion holes 51. The number of magnet insertion holes 51 is six here. In other words, the number of poles is six. However, the number of poles is not limited to six, and may be two or more.

The magnet insertion hole 51 extends linearly in a direction perpendicular to a line passing through the circumferential center of the magnet insertion hole 51. However, the magnet insertion hole 51 is not limited to this shape, and may extend, for example, in a V-shape.

One permanent magnet 60 is placed in each magnet insertion hole 51. The permanent magnet 60 is flat and has a width in the circumferential direction of the rotor core 50 and a thickness in the radial direction. Each permanent magnet 60 is magnetized in the thickness direction.

The permanent magnets 60 are, for example, rare earth magnets. The rare earth magnets are, for example, neodymium magnets containing neodymium (Nd), iron (Fe) and boron (B). Two or more permanent magnets 60 may be placed in each magnet insertion hole 51.

In the rotor core 50, flux barriers 52, which are holes, are formed at both circumferential ends of the magnet insertion holes 51. A thin-walled portion is formed between each flux barrier 52 and the outer periphery of the rotor core 50. The radial width of the thin-walled portion is set to be the same as the plate thickness of the electromagnetic steel plate, for example.

Slits 54 are formed between the magnet insertion holes 51 and the outer periphery of the rotor core 50. The slits 54 are formed to regulate the flow of magnetic flux emitted from the permanent magnets 60. Here, seven slits 54 are formed symmetrically with respect to the circumferential center of the magnet insertion holes 51. However, the number and arrangement of the slits 54 are not limited to the example described here. In addition, the rotor core 50 does not necessarily have to have slits 54.

In the rotor core 50, holes 57, 58 are formed radially inward from the magnet insertion hole 51. The

holes

57, 58 are used as vents to allow refrigerant to pass through or as holes for inserting jigs. The same number of

holes

57, 58 are formed as the number of poles. The circumferential position of each hole 57 coincides with the circumferential center of the magnet insertion hole 51. The circumferential position of each hole 58 coincides with the inter-pole portion. However, the number and arrangement of the

holes

57, 58 are not limited to the example described here. Furthermore, the rotor core 50 does not necessarily have to have the

holes

57, 58.

Furthermore, a crimping portion 56 for fixing the electromagnetic steel plate of the rotor core 50 is formed on the radial outside of each hole portion 58. However, the arrangement of the crimping portion 56 is not limited to the example described here. Furthermore, the electromagnetic steel plate of the rotor core 50 may be fixed by a method other than crimping.

<Stator Configuration>
The stator 1 has a stator core 10 that surrounds the rotor core 50 from the radial outside, and a winding 30 wound around the stator core 10. The stator core 10 is made by stacking a plurality of electromagnetic steel plates in the axial direction and fixing them by crimping, etc. The thickness of the electromagnetic steel plates is 0.1 to 0.7 mm.

The stator core 10 has an annular core back 11 centered on the axis Ax, and a number of teeth 12 extending radially inward from the core back 11. The teeth 12 are arranged at regular intervals in the circumferential direction. Here, the number of teeth 12 is nine. However, the number of teeth 12 is not limited to nine, and may be two or more. Slots 14 are formed between adjacent teeth 12 in the circumferential direction. The number of slots 14 is nine, the same as the number of teeth 12.

The winding 30 is made of magnet wire and is wound around each tooth 12 in a concentrated manner. The outer diameter, i.e., wire diameter, of the magnet wire is, for example, 1.0 mm. The number of turns of the winding 30 around one tooth 12 is, for example, 80 turns.

The windings 30 are made of aluminum wire or copper wire. Aluminum wire is particularly desirable because it is softer than copper wire and can be tightly wound around the teeth 12. Aluminum wire is also less expensive than copper wire, which is advantageous in reducing manufacturing costs.

Figure 2 is a diagram showing the axial positional relationship between the stator core 10 and the rotor core 50. As shown in Figure 2, the stator core 10 and the rotor core 50 are at the same axial position. That is, both axial end faces 10e of the stator core 10 are at the same axial position as both axial end faces 50e of the rotor core 50.

The axial positional relationship between the stator core 10 and the rotor core 50 is not limited to the example shown in FIG. 2, as long as the axial center position of the stator core 10 and the axial center position of the rotor core 50 coincide. Also, the axial center position of the stator core 10 and the axial center position of the rotor core 50 do not have to coincide, but this will be explained in embodiment 3.

FIG. 3 is a plan view showing the stator core 10. The core back 11 has an inner peripheral surface 11a and an outer peripheral surface. The inner peripheral surface 11a of the core back 11 faces the slots 14. The outer peripheral surface of the core back 11 fits into the shell 80 of the compressor 8 (FIG. 26).

A groove 18a is formed in the outer peripheral surface of the core back 11 in a portion located radially outward of the teeth 12. A protrusion 17a is formed on both circumferential sides of the groove 18a. A notch 18b is formed at a position where the protrusion 17a is sandwiched circumferentially between the groove 18a and the notch 18b. A protrusion 17b is formed at a position where the notch 18b is sandwiched circumferentially between the protrusion 17a and the notch 18b.

The outer peripheral surfaces of the

protrusions

17a and 17b form part of the outer peripheral surface of the core back 11 and fit into the inner peripheral surface of the shell 80 of the compressor 8 (Fig. 26). The groove 18a is a groove that extends in the axial direction and functions as a refrigerant passage in the compressor 8. The notch 18b is provided to relieve the stress that the core back 11 receives from the shell 80 of the compressor 8 (Fig. 26).

As described above, the teeth 12 extend radially inward from the core back 11. A radial line passing through the circumferential center of each tooth 12 is called the teeth centerline T. The teeth 12 have a pair of side surfaces 12a on both circumferential sides. The side surfaces 12a of the teeth 12 face the slots 14.

Each tooth 12 also has a tooth tip portion 13 that faces the rotor 5 (Figure 1). The tooth tip portion 13 has a circumferential width greater than the other portions of the tooth 12, and protrudes circumferentially beyond the side surface 12a of the tooth 12. An outer surface 13a is formed radially outward of the protruding portion of the tooth tip portion 13. The outer surface 13a of the tooth tip portion 13 faces the slot 14.

Note that although the tooth tips 13 are part of the teeth 12, they have a different shape from the other parts of the teeth 12, so the tooth tips 13 may be described separately from the other parts of the teeth 12.

A step portion 12S is formed at the axial end of the tooth 12. The step portion 12S is formed on the side surface 12a side of the tooth 12, i.e., on the slot 14 side. Therefore, the circumferential width of the tooth 12 is narrower at the axial end than at the axial center of the stator core 10.

A step portion 11S is formed at the axial end of the core back 11. The step portion 11S is formed on the inner peripheral surface 11a side of the core back 11, i.e., on the slot 14 side. Therefore, the radial width of the core back 11 is narrower at the axial end than at the axial center of the stator core 10.

A step portion 13S is formed at the axial end of the tooth tip portion 13. The step portion 13S is formed on the outer surface 13a side of the tooth tip portion 13, i.e., on the slot 14 side. Therefore, the radial width of the protruding portion of the tooth tip portion 13 is narrower at the axial end portion than at the axial center portion of the stator core 10.

The stator core 10 is constructed by combining multiple split cores 15, each of which includes one tooth 12, in a ring shape. The number of split cores 15 is the same as the number of teeth 12, which is nine in this example.

Adjacent split cores 15 are connected to each other by crimped portions 16 formed on the outer periphery of the core back 11. Note that the connecting portions of the split cores 15 are not limited to the crimped portions 16 and may be, for example, thin-walled portions. Also, instead of providing connecting portions, adjacent split cores 15 may be joined by welding.

FIG. 4 is a perspective view showing the split core 15. In FIG. 4, the direction of the axis Ax (FIG. 1), i.e., the axial direction, is indicated by arrow Z. The core back 11 has an axial end face 11e, the teeth 12 have an axial end face 12e, and the tooth tip portion 13 has an axial end face 13e. The end faces 11e, 12e, and 13e are on the same plane and correspond to the end face 10e shown in FIG. 2.

The step portion 12S of the tooth 12 is formed between the end face 12e and the side face 12a of the tooth 12. The step portion 12S is composed of a wall surface 12b facing the slot 14 and a bottom surface 12c facing the axial direction. The wall surface 12b is parallel to the axial direction, and the bottom surface 12c is perpendicular to the axial direction.

The step portion 11S of the core back 11 is formed between the end face 11e and the inner peripheral surface 11a of the core back 11. The step portion 11S is composed of a wall surface 11b facing the slot 14 and a bottom surface 11c facing the axial direction. The wall surface 11b is parallel to the axial direction, and the bottom surface 11c is perpendicular to the axial direction.

The step portion 13S of the tooth tip portion 13 is formed between the end face 13e of the tooth tip portion 13 and the outer surface 13a. The step portion 13S is composed of a wall surface 13b facing the slot 14 and a bottom surface 13c facing the axial direction. The wall surface 13b is parallel to the axial direction, and the bottom surface 13c is perpendicular to the axial direction.

The bottom surfaces 11c, 12c, and 13c of the

step portions

11S, 12S, and 13S are at the same position in the axial direction. Therefore, the axial heights of the

step portions

11S, 12S, and 13S are the same.

The step portion 11S of the core back 11 has an intermediate step portion 11T formed as a protrusion. The intermediate step portion 11T has a first surface parallel to the end face 11e of the core back 11 and a second surface parallel to the inner peripheral surface 11a of the core back 11.

The step portion 12S of the tooth 12 has an intermediate step portion 12T formed as a protrusion. The intermediate step portion 12T has a first surface 121 (FIG. 6) parallel to the end surface 12e of the tooth 12, and a second surface 122 (FIG. 6) parallel to the side surface 12a of the tooth 12.

The step portion 13S of the tooth tip portion 13 is formed with an intermediate step portion 13T as a protrusion. The intermediate step portion 13T has a first surface parallel to the end face 13e of the tooth tip portion 13 and a second surface parallel to the outer surface 13a of the tooth tip portion 13.

The first surfaces of the

intermediate steps

11T, 12T, and 13T are located at the same position in the axial direction. In other words, the axial heights of the

intermediate steps

11T, 12T, and 13T are the same.

The split core 15 has a core portion 15a in the axial center, core portions 15b on both axial sides of core portion 15a, and core portions 15c on both axial ends. Core portion 15b is located in the axial region where

intermediate stages

11T, 12T, and 13T are formed. Core portion 15c is located on the end face 10e side of core portion 15b in the axial direction.

Compared to core portion 15a, core portion 15b has a narrower width of core back 11, a narrower width of teeth 12, and a narrower width of protruding portion of tooth tip 13.Compared to core portion 15b, core portion 15c has an even narrower width of core back 11, a narrower width of teeth 12, and a narrower width of protruding portion of tooth tip 13.

FIG. 5 is a perspective view showing the split core 15 and the insulating portion 20. The insulating portion 20 is attached to the split core 15 so as to cover the teeth 12 from both axial and circumferential sides. The insulating portion 20 is made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP).

The insulating portion 20 has a body portion 21 that covers the teeth 12, a wall portion 22 that is arranged radially outside the body portion 21, and a flange portion 23 that is arranged radially inside the body portion 21. The wall portion 22 and the flange portion 23 face each other in the radial direction with the body portion 21 in between.

The wall portion 22 is provided to cover the inner peripheral surface 11a of the core back 11 and protrudes on both sides in the axial direction. The wall portion 22 has an engagement portion 22a that engages with the step portion 11S of the core back 11.

The body 21 is provided to cover the end faces 12e and side faces 12a (Fig. 4) of the teeth 12. The body 21 has an engagement portion 21a (Fig. 6) that engages with the step portion 12S (Fig. 4) of the teeth 12.

The flange portion 23 is provided to cover the end face 13e (FIG. 4) and the outer surface 13a of the tooth tip portion 13. The flange portion 23 has an engagement portion 23a that engages with the step portion 13S of the tooth tip portion 13.

The winding 30 (Figure 1) is wound around the body 21. The wall 22 and the flange 23 guide the winding 30 wound around the body 21 from both radial sides.

The insulating section 20 is formed, for example, by molding resin integrally with the split core 15. The insulating section 20 may also be a resin molded body attached to the split core 15.

Here, we will explain the insulating part 20 that is constructed as an integral part, but the insulating part 20 may also be constructed from an insulator and an insulating film. This will be explained in embodiment 4.

Figure 6 is a cross-sectional view showing the teeth 12 and the insulating portion 20, taken along a plane perpendicular to the extension direction of the teeth 12. The extension direction of the teeth 12 refers to a radial line passing through the circumferential center of the teeth 12, i.e., the direction of the teeth centerline T (Figure 3).

The teeth 12 have a length L1 in the axial direction. The length L1 is the distance between both end faces 12e of the teeth 12. The teeth 12 also have a width W1 at the center in the axial direction, a width W2 in the area where the intermediate step portion 12T is formed, and a width W3 at the axial end portions.

Width W1 is the distance between both side surfaces 12a of the teeth 12. Width W2 is the distance between the second surfaces 122 of the two intermediate step portions 12T of the teeth 12. Width W3 is the distance between the wall surfaces 12b of the two step portions 12S of the teeth 12. The relationship between widths W1, W2, and W3 is W1>W2>W3.

The insulating portion 20 has a first surface 201, which is a flat surface covering the end surface 12e of the tooth 12, a second surface 202, which is a flat surface facing the slot 14, and a third surface 203, which is a curved or inclined surface extending from the first surface 201 to the second surface 202.

The first surface 201 is a plane extending in a plane perpendicular to the axial direction and faces the end surface 12e of the tooth 12.

The second surface 202 is a plane extending in a plane parallel to the axial direction and faces the side surface 12a of the tooth 12.

The third surface 203 is a curved surface that connects the first surface 201 and the second surface 202 in a curved line in a cross section perpendicular to the extension direction of the teeth 12, or an inclined surface that connects the first surface 201 and the second surface 202 in a straight line. Below, a case where the third surface 203 is a curved surface will be described, but it may also be an inclined surface (see FIG. 25 described later).

FIG. 7 is an enlarged view of a portion of the tooth 12 including the step portion 12S. As described above, the step portion 12S is formed between the end face 12e and the side face 12a of the tooth 12, and an intermediate step portion 12T is formed in the step portion 12S.

The intermediate step portion 12T has a first surface 121 facing the axial direction and a second surface 122 facing the slot 14. The first surface 121 of the intermediate step portion 12T is parallel to the end surface 12e of the tooth 12. The second surface 122 of the intermediate step portion 12T is parallel to the side surface 12a of the tooth 12.

A corner E is formed between the first surface 121 and the second surface 122 of the intermediate step portion 12T. The corner E is the ridge line (the intersection in the cross section of FIG. 7) between the first surface 121 and the second surface 122. The corner E is the part of the step portion 12S of the tooth 12 that is closest to the third surface 203 of the insulating portion 20.

The shortest distance from the end face 12e of the tooth 12 to the first surface 201 of the insulating portion 20 (more specifically, the body portion 21) is defined as T1. The shortest distance from the side face 12a of the tooth 12 to the second surface 202 of the insulating portion 20 is defined as T2. The shortest distance from the corner E of the intermediate step portion 12T to the third surface 203 of the insulating portion 20 is defined as T3.

The shortest distance T1 from the end face 12e of the tooth 12 to the first surface 201 of the insulating portion 20 and the shortest distance T3 from the corner E of the intermediate step portion 12T to the third surface 203 of the insulating portion 20 satisfy T1>T3.

Furthermore, the shortest distance T2 from the side surface 12a of the tooth 12 to the second surface 202 of the insulating portion 20 and the shortest distance T3 from the corner E of the intermediate step portion 12T to the third surface 203 of the insulating portion 20 satisfy T3>T2. In other words, these shortest distances T1, T2, and T3 satisfy T1>T3>T2.

<Action>
The operation of the first embodiment will be described in comparison with comparative examples 1 to 3. Fig. 8(A) is a cross-sectional view showing the tooth 12 and the insulating portion 20 of comparative example 1. Fig. 8(B) is a cross-sectional view showing the tooth 12 and the insulating portion 20 of comparative example 2. Fig. 8(C) is a cross-sectional view showing the tooth 12 and the insulating portion 20 of comparative example 3.

In Figures 8(A) to (C), for ease of comparison, the components in Comparative Examples 1 to 3 are given the same reference numerals as those in the first embodiment.

The teeth 12 of Comparative Example 1 shown in FIG. 8(A) do not have a step between the end faces 12e and the side faces 12a. That is, a 90-degree corner is formed between the end faces 12e and the side faces 12a of the teeth 12. The insulating portion 20 has a first surface 201 that covers the end faces 12e of the teeth 12, a second surface 202 that faces the slot 14, and a third surface 203 between these

surfaces

201, 202. The third surface 203 faces the corner of the teeth 12.

In order to wind the winding 30 around the insulating part 20 without causing any bulging, it is desirable for the radius of curvature of the third surface 203 to be large. However, in order to increase the radius of curvature of the third surface 203, it is necessary to increase the shortest distance T1 from the end surface 12e of the tooth 12 to the first surface 201 of the insulating part 20. This increases the circumferential length of the winding 30, resulting in increased copper loss.

The teeth 12 of Comparative Example 2 shown in FIG. 8(B) do not have a step portion at the axial end, like the teeth 12 of Comparative Example 1. In other words, a 90-degree corner is formed between the end face 12e and the side face 12a of the teeth 12. In Comparative Example 2, the shortest distance T1 from the end face 12e of the teeth 12 to the first surface 201 of the insulating portion 20 is shorter than in Comparative Example 1.

In this comparative example 2, the shortest distance T1 is short, so the radius of curvature of the third surface 203 is small, and the winding 30 is likely to bulge toward the slot 14. This increases the perimeter of the winding 30, and makes it difficult to arrange the winding 30 densely within the slot 14.

The tooth 12 of Comparative Example 3 shown in FIG. 8(C) has a step portion 12S between the end face 12e and the side face 12a. The insulating portion 20 has a first surface 201 that covers the end face 12e of the tooth 12, a second surface 202 that faces the slot 14, and a third surface 203 that covers the step portion 12S.

In this comparative example 3, a step portion 12S is formed on the tooth 12, so that the radius of curvature of the third surface 203 can be increased and the shortest distance T1 from the end surface 12e of the tooth 12 to the first surface 201 of the insulating portion 20 can be shortened.

However, as shown in an enlarged view in FIG. 9, in the step portion 12S of the tooth 12 in Comparative Example 3, there is a portion (indicated by reference symbol 204) where the thickness of the insulating portion 20 is excessively thick, and the width of the tooth 12 at the axial end portion is accordingly narrower. As a result, magnetic saturation is more likely to occur within the tooth 12, and iron loss increases.

In this embodiment, as shown in FIG. 7, an intermediate step portion 12T is provided at the step portion S of the tooth 12. By providing the intermediate step portion 12T, the width of the tooth 12 is increased, suppressing magnetic saturation and thereby suppressing an increase in iron loss.

In addition, the radius of curvature of the third surface 203 can be increased without excessively increasing the thickness of the insulating portion 20, thereby suppressing the winding bulge of the winding 30.

On the other hand, if an intermediate step 12T is provided on the step portion 12S of the tooth 12, a thin portion of the insulating portion 20, i.e., a portion of the shortest distance T3 shown in FIG. 7, will be created between the intermediate step 12T and the third surface 203 of the insulating portion 20. This point will be explained below.

FIG. 10 is a cross-sectional view of the teeth 12 and the windings 30 taken along a plane perpendicular to the direction in which the teeth 12 extend. In FIG. 10, the arrows indicate the force acting around one of the four corners of the teeth 12.

The teeth 12 have an axial length L1 (FIG. 6) that is longer than their width W1 (FIG. 6). In other words, the cross-sectional shape of the teeth 12 is a rectangle that is long in the axial direction. Therefore, the winding 30 is wound around the insulating portion 20 in an elliptical shape that is long in the axial direction.

In the winding process, tension is applied to the winding 30, and this tension causes the winding 30 to contact the first surface 201, the second surface 202, and the third surface 203 of the insulating part 20. In other words, stress is applied from the winding 30 to the first surface 201, the second surface 202, and the third surface 203 of the insulating part 20.

As described above, the cross-sectional shape of the teeth 12 is a rectangle that is long in the axial direction, so the greatest force acts on the first surface 201 of the insulating part 20. In other words, the force F1 that the first surface 201 of the insulating part 20 receives from the winding 30 is greater than the force F2 that the second surface 202 receives from the winding 30.

The force F1 that the first surface 201 of the insulating portion 20 receives from the winding 30 is maximum at the portion facing the corner K between the end surface 12e of the tooth 12 and the wall surface 12b of the step portion 12S.

As shown in FIG. 7, the shortest distance T1 from the end face 12e of the tooth 12 to the first surface 201 of the insulating portion 20 is longer than the shortest distance T3 from the corner E of the intermediate step portion 12T of the tooth 12 to the third surface 203 of the insulating portion 20. Therefore, damage to the insulating portion 20 can be prevented when the first surface 201 of the insulating portion 20 receives a force F1 from the winding 30.

Furthermore, the shortest distance T3 from the corner E of the intermediate step 12T of the tooth 12 to the third surface 203 of the insulating portion 20 is longer than the shortest distance T2 from the side surface 12a of the tooth 12 to the second surface 202 of the insulating portion 20. Therefore, damage to the insulating portion 20 can be prevented when the third surface 203 of the insulating portion 20 receives a force F3 from the winding 30.

Because the force F2 that the second surface 202 of the insulating portion 20 receives from the winding 30 is the smallest, the shortest distance T2 from the side surface 12a of the tooth 12 to the second surface 202 of the insulating portion 20 can be made the shortest. This makes it possible to increase the area of the slot 14 and efficiently accommodate the winding 30.

FIG. 11 is a diagram for explaining the dimensions of the step portion 12S of the tooth 12 and the third surface 203 of the insulating portion 20. In FIG. 11, the axial dimension of the step portion 12S is taken as height A. This height A corresponds to the axial distance from the bottom surface 12c of the step portion 12S to the end surface 12e of the tooth 12.

In a cross section perpendicular to the extension direction of the teeth 12, the dimension of the step portion 12S in the direction perpendicular to the axial direction (also called the width direction) is defined as width B. This width B corresponds to the distance in the width direction from the wall surface 12b of the step portion 12S to the side surface 12a of the teeth 12.

In the example shown in FIG. 11, the height A and width B of the step portion 12S of the tooth 12 satisfy the relationship A≧B. When A>B, the third surface 203 extends to form a long elliptical arc in the axial direction. When A=B, the third surface 203 extends to form a circular arc.

The first surface 201 of the insulating portion 20 covers the end surface 12e of the tooth 12 and also protrudes into the step portion 12S. The second surface 202 of the insulating portion 20 covers the side surface 12a of the tooth 12 and also protrudes into the step portion 12S.

In a cross section perpendicular to the extension direction of the teeth 12, the boundary between the first surface 201 and the third surface 203 is designated as point P. The boundary between the second surface 202 and the third surface 203 is designated as point Q. Points P and Q define both ends of the third surface 203.

The distance in the axial direction between points P and Q is distance D1. The distance in the direction perpendicular to the axial direction (i.e., the width direction) between points P and Q is distance D2. In other words, if the intersection point of a first straight line L1 that passes through point P and is parallel to the axial direction, and a second straight line L2 that passes through point Q and is perpendicular to the axial direction is U, then distance D1 corresponds to the distance from point P to intersection point U, and distance D2 corresponds to the distance from point Q to intersection point U.

The height A and width B of the step portion 12S and the distances D1 and D2 satisfy D1≦A and D2≦B. In other words, point P does not face the end face 12e of the tooth 12, and point Q does not face the side face 12a of the tooth 12.

When point P faces end face 12e of tooth 12, a locally thin portion is created between third surface 203 of insulating portion 20 and end face 12e of tooth 12. Similarly, when point Q faces side surface 12a of tooth 12, a locally thin portion is created between third surface 203 and side surface 12a of tooth 12.

In contrast, in embodiment 1, point P does not face the end face 12e of the tooth 12, and point Q does not face the side face 12a of the tooth 12. Therefore, there are no locally thin portions of the insulating portion 20.

As such, since there are no locally thin portions of the insulating portion 20, damage to the insulating portion 20 can be prevented even if the shortest distance T1 from the end face 12e of the tooth 12 to the first surface 201 of the insulating portion 20 is shortened. This makes it possible to increase the radius of curvature of the third surface 203 to suppress swelling of the winding 30, and to reduce the shortest distance T1, i.e., the thickness, to shorten the perimeter of the winding 30. As a result, copper loss can be effectively reduced.

The shape of the third surface 203 of the insulating portion 20 is set to match the shape of the step portion 12S of the tooth 12. Figures 12(A) to (E) are diagrams showing examples of the step portion 12S of the tooth 12 and the third surface 203 of the insulating portion 20. The intermediate step portion 12T is omitted in Figures 12(A) to (E).

In Figures 12(A) to (C), the third surface 203 of the insulating portion 20 has the same arc shape, but the shape of the step portion 12S is different.

As shown in FIG. 12(A), when the height A and width B of the step portion 12S satisfy A=B, points P and Q of the insulating portion 20 can be made not to face the end face 12e and side face 12a of the tooth 12.

On the other hand, as shown in FIG. 12(B), when the height A and width B of the step portion 12S satisfy A<B, point Q faces the side surface 12a of the tooth 12. Also, as shown in FIG. 12(C), when the height A and width B of the step portion 12S satisfy A>B, point P faces the end surface 12e of the tooth 12.

In contrast, as shown in FIG. 12(D), if the third surface 203 of the insulating portion 20 has an elliptical arc shape that is long in the width direction, when the height A and width B of the step portion 12S satisfy A<B, it is possible to prevent points P and Q of the insulating portion 20 from facing the end surface 12e and side surface 12a of the tooth 12.

Furthermore, as shown in FIG. 12(E), if the third surface 203 of the insulating portion 20 has an elliptical arc shape that is long in the axial direction, when the height A and width B of the step portion 12S satisfy A>B, it is possible to prevent points P and Q of the insulating portion 20 from facing the end surface 12e and side surface 12a of the tooth 12.

In other words, when the height A and width B of the step portion 12S satisfy A=B, it is desirable that the third surface 203 of the insulating portion 20 has a circular arc shape. When the height A and width B of the step portion 12S satisfy A>B, it is desirable that the third surface 203 of the insulating portion 20 has an elliptical arc shape that is long in the axial direction. When the height A and width B of the step portion 12S satisfy A<B, it is desirable that the third surface 203 of the insulating portion 20 has an elliptical arc shape that is long in the width direction.

Figures 13(A) and (B) are diagrams showing the portion including the step portion 12S of the teeth 12 and the bulging state of the winding 30 when the third surface 203 of the insulating portion 20 has an elliptical shape. The intermediate step portion 12T is omitted in Figures 13(A) and (B).

As shown in FIG. 13(A), when the height A and width B of the step portion 12S satisfy A<B, the circumferential bulge of the winding 30 increases as indicated by the symbol B1. In other words, the winding 30 bulges so as to protrude into the slot 14.

In contrast, as shown in FIG. 13(B), when the height A and width B of the step portion 12S satisfy A>B, the axial bulge of the winding 30 increases, as indicated by the symbol B2. In other words, the winding 30 bulges outward from the tooth 12 in the axial direction.

13(A) and (B), the circumference length increases when the winding 30 bulges. However, in the case shown in FIG. 13(A), the arrangement density of the winding 30 in the slot 14 decreases, whereas in the case shown in FIG. 13(B), there is little effect on the arrangement density of the winding 30 in the slot 14.

For this reason, as shown in FIG. 13(B), it is desirable that the height A and width B of the step portion 12S satisfy A>B. Also, as shown in FIG. 12(A), the height A and width B of the step portion 12S may satisfy A=B. In other words, it is desirable that the height A and width B of the step portion 12S satisfy A≧B.

Next, we will explain the relationship between the axial height A of the step portion 12S and the axial length L1 of the tooth 12.

FIG. 14 is a graph showing the relationship between the ratio A/L1 of the height A of the step portion 12S to the length L1 of the tooth 12 and the iron loss and copper loss (relative values) when the step portion 12S of the tooth 12 does not have an intermediate step portion 12T.

The values of iron loss and copper loss were obtained by performing an analysis in which the height A and width B were changed so that the ratio ((A x B)/(L1 x W1)) of the cross-sectional area (A x B) of the step portion 12S to the cross-sectional area (L1 x W1) of the tooth 12 without the step portion 12S was constant. The values of iron loss and copper loss are expressed as relative values to the values of iron loss and copper loss when the tooth 12 does not have the step portion 12S.

As shown in Figure 14, as the value of A/L1 increases, copper loss decreases and iron loss increases. The reason that copper loss decreases as the value of A/L1 increases is that, assuming that the cross-sectional area (A x B) of step 12S is constant, as the height A of step 12S increases (i.e., the width B decreases), magnetic saturation is suppressed and magnetic flux from rotor 5 flows in more easily, and the magnetic flux can be effectively utilized, increasing the torque constant and allowing the current value to be reduced.

The reason why the iron loss increases as the value of A/L1 increases is that as the ratio of the height A of the step portion 12S to the length L1 of the tooth 12 increases, the ratio of the narrow portion of the tooth 12 increases, and the magnetic resistance of the entire tooth 12 increases.

In addition, because the step portion 11S of the core back 11 and the step portion 13S of the tooth tip 13 are formed at the same height (i.e., axial position) as the step portion 12S of the tooth 12 (see FIG. 4), the magnetic path length within the tooth 12 from the core back 11 to the tooth tip 13 becomes longer. Therefore, as the ratio of the height A of the step portion 12S to the length L1 of the tooth 12 increases, the portion of the tooth 12 with a long magnetic path length increases, and as described above, iron loss increases.

When the value of A/L1 becomes large enough, the width B of step 12S and the widths of

steps

11S and 13S become small enough because the value of A×B is kept constant, so the effect of the increase in magnetic path length described above decreases, and as a result, the increase in iron loss saturates as shown in FIG. 14.

Fig. 15 is a graph showing the relationship between the ratio A/L1 of the height A of step portion 12S to the length L1 of tooth 12 when intermediate step portion 12T is provided in step portion 12S of tooth 12, and the iron loss and copper loss (relative values). The values of iron loss and copper loss are as described in Fig. 14.

For the analysis, the height A and width B of the step portion 12S were changed as explained in FIG. 14, and the height and width of the intermediate step portion 12T were changed accordingly. For the intermediate step portion 12T, as shown in FIGS. 16(A) and (B), in a cross section perpendicular to the extension direction of the teeth 12, a virtual elliptical arc M is set with its center at the intersection J between the bottom surface 12c and the wall surface 12b of the step portion 12S, length A as its major axis radius, and width B as its minor axis radius. Then, the height and width of the intermediate step portion 12T are determined so that the midpoint of the elliptical arc M coincides with the corner E of the intermediate step portion 12T.

In Figure 15, compared to Figure 14, the iron loss and copper loss values are both smaller across the entire range of A/L1.

From Figure 15, the rate of increase in iron loss and the rate of decrease in copper loss are the same when A/L1 = 0.141 compared to when the teeth 12 do not have the step portion 12S. When A/L1 = 0.141, copper loss increases by 0.65% and iron loss also increases by 0.65% compared to when the teeth 12 do not have the step portion 12S.

When A/L1<0.141, the increase in copper loss is greater than the increase in iron loss, compared to when the teeth 12 do not have the step portion 12S. When A/L1>0.141, the increase in iron loss is greater than the increase in copper loss, compared to when the teeth 12 do not have the step portion 12S.

In this embodiment, copper loss can be reduced by preventing the winding 30 from expanding, so it is desirable to have A/L1≦0.141, where the increase in iron loss is equal to or smaller than the increase in copper loss.

The electric motor 100 used in the compressor is designed according to the required specifications of the compressor, but it is desirable to keep the shape of the stator core 10 common and respond to various required specifications by adjusting the width of the core back 11 or teeth 12, or the number of turns of the winding 30, etc. In this embodiment, copper loss and iron loss can be reduced by the shape of the teeth 12, so a highly efficient electric motor 100 that responds to various required specifications can be realized.

Although an example in which the stator core 10 is made up of multiple split cores 15 has been described here, the stator core 10 is not limited to this configuration. In other words, the stator core 10 may be an integrated core in which electromagnetic steel sheets punched into an annular shape are stacked in the axial direction.

In addition, although an example in which step portions 12S are formed on both circumferential sides of the teeth 12 has been described here, it is sufficient that step portions 12S are formed on at least one circumferential side of the teeth 12.

In addition, here, steps 11S, 13S are provided on the core back 11 and the tooth tip portion 13, but since the winding 30 is not wound on the core back 11 and the tooth tip portion 13, steps 11S, 13S on the core back 11 and the tooth tip portion 13 do not necessarily have to be provided.

<Effects of the embodiment>
As described above, the stator 1 of the first embodiment has a core back 11 and teeth 12, and the windings 30 are wound around the teeth 12 via the insulating portion 20. The teeth 12 have end faces 12e that define the axial ends of the teeth 12, side faces 12a that face the slots 14, step portions 12S formed between the end faces 12e and the side faces 12a, and intermediate step portions 12T provided in the step portions 12S. The insulating portion 20 has a first surface 201 that covers the end faces 12e of the teeth 12, a second surface 202 that faces the slots 14, and a third surface 203 that is a curved surface or an inclined surface extending from the first surface 201 to the second surface 202. The shortest distance T1 from the end face 12e of the tooth 12 to the first surface 201 of the insulating portion 20 and the shortest distance T3 from the intermediate step portion 12T to the third surface 203 of the insulating portion 20 satisfy T1>T3.

Since the intermediate step 12T is provided at the step 12S of the teeth 12 in this way, the cross-sectional area of the teeth 12 can be increased while suppressing the swelling of the winding 30. In addition, due to the relationship T1>T3, the thickness of the insulating part 20 can be made thin while ensuring strength. Therefore, the circumferential length of the winding 30 can be shortened to reduce copper loss and suppress an increase in iron loss.

Furthermore, the shortest distance T3 from the intermediate step 12T to the third surface 203 of the insulating portion 20 and the shortest distance T2 from the side surface 12a of the tooth 12 to the second surface 202 of the insulating portion 20 satisfy T3>T2. Since the second surface 202 of the insulating portion 20 receives small stress during the winding process of the winding 30, the winding 30 can be densely arranged within the slot 14 by reducing the thickness of the portion including the second surface 202 of the insulating portion 20 (corresponding to the shortest distance T2).

Furthermore, in a cross section perpendicular to the extension direction of the teeth 12, if the boundary between the first surface 201 and the third surface 203 of the insulating portion 20 is defined as point P, the boundary between the second surface 202 and the third surface 203 is defined as point Q, and the intersection point U of a first straight line L1 that passes through point P and is parallel to the axial direction and a second straight line L2 that passes through point Q and is perpendicular to the axial direction is defined as point U, then the axial height A of the step portion 12S, the width B of the step portion 12S in a direction perpendicular to the axial direction, the distance D1 from point P to the intersection point U, and the distance D2 from point Q to the intersection point U satisfy D1≦A and D2≦B. That is, point P of the insulating portion 20 does not face the end face 12e of the teeth 12, and point Q of the insulating portion 20 does not face the side surface 12a of the teeth 12. Therefore, even if the radius of curvature of the third surface 203 of the insulating part 20 is increased, there are no locally thin areas, and stress concentration on the insulating part 20 can be suppressed.

In addition, because the height A and width B of the step portion 12S satisfy A ≥ B, it is possible to suppress the winding 30 from expanding into the slot 14, thereby improving the arrangement density of the winding 30 within the slot 14.

In addition, the axial height A of the step portion 12S and the axial length L1 of the stator core 10 satisfy A/L1≦0.141, which reduces copper loss in the windings 30 and suppresses increases in iron loss in the teeth 12.

Embodiment 2.
Next, a description will be given of embodiment 2. In embodiment 1, one intermediate step portion 12T is formed in step portion 12S of tooth 12. In contrast, in embodiment 2, two or more intermediate step portions 12T are formed in step portion 12S of tooth 12.

First, the imaginary curved surface G defined in the second embodiment will be described. Figures 17(A) and (B) are diagrams for explaining the imaginary curved surface G. Figure 17(A) shows a case where the height A and width B of the step portion 12S satisfy A=B, and Figure 17(B) shows a case where the height A and width B of the step portion 12S satisfy A>B. In Figures 17(A) and (B), one intermediate step portion 12T is provided in the step portion 12S, as in the first embodiment.

As shown in Figures 17(A) and (B), the imaginary curved surface G is a curved surface that is parallel to the third surface 203 of the insulating portion 20 and extends from the end surface 12e of the tooth 12 to the side surface 12a. The distance between the imaginary curved surface G and the third surface 203 of the insulating portion 20 is the shortest distance T3 described above.

As shown in FIG. 17(A), when the step portion 12S of the tooth 12 satisfies A=B, the cross-sectional area of the intermediate step portion 12T is maximum when the corner E of the intermediate step portion 12T coincides with the point V that bisects the imaginary curved surface G.

On the other hand, when the step portion 12S of the tooth 12 satisfies A>B as shown in FIG. 17(B), the cross-sectional area of the intermediate step portion 12T is maximum when the corner portion E of the intermediate step portion 12T is located closer to the end face 12e of the tooth 12 than the point V that bisects the imaginary curved surface G.

Conversely, when the step portion 12S of the tooth 12 satisfies A < B, the cross-sectional area of the intermediate step portion 12T is maximum when the corner E of the intermediate step portion 12T is located closer to the side surface 12a of the tooth 12 than the point V that bisects the imaginary curved surface G.

The stator 1 of embodiment 2 has two or more intermediate step portions 12T in the step portion 12S of the teeth 12, and is configured so that the cross-sectional area of these is maximized.

FIG. 18 is a cross-sectional view showing the step portion 12S of the tooth 12 in embodiment 2. In the example shown in FIG. 18, the step portion 12S of the tooth 12 has a shape that satisfies A>B, and n (n is 2 or more) intermediate step portions 12T are provided in this step portion 12S. Here, n is 3.

The points obtained by dividing the imaginary curved surface G into (n+1) equal parts are designated as points V1, V2, ..., Vn, in order from the end face 12e side of the teeth 12. Here, since n=3, the points obtained by dividing the imaginary curved surface G into four equal parts are designated as points V1, V2, V3, in order from the end face 12e side of the teeth 12.

Of the three intermediate step portions 12T, the cross-sectional area of the intermediate step portion 12T closest to the end face 12e of the tooth 12 (referred to as intermediate step portion _12T1 ) is the largest when the corner _E1 of intermediate step portion 12T1 is located closer to the end face 12e of the tooth 12 than point V1.

Furthermore, among the three intermediate step portions 12T, the cross-sectional area of the intermediate step portion 12T (referred to as intermediate step portion _12T2 ) that is second closest to the end face 12e of the tooth ₁₂ is the largest when the corner E2 of the intermediate step portion 12T2 is located closer to the end face 12e of the tooth 12 than point V2.

Furthermore, among the three intermediate step portions 12T, the cross-sectional area of the intermediate step portion 12T farthest from the end face 12e of the tooth 12 (referred to as intermediate step portion _12T3 ) is the largest when the corner _E3 of intermediate step portion 12T3 is located closer to the end face 12e of the tooth 12 than point V2.

In this way, by forming n intermediate step portions 12T ₁ to 12 _n in the step portion 12S of the tooth 12 and positioning these corner portions E1 to En closer to the end face 12e of the tooth 12 than the points V1 to Vn obtained by equally dividing the imaginary curved surface G into (n+1) parts, the cross-sectional area of each of the intermediate step portions 12T ₁ to 12 _n can be maximized.

As a result, the amount of insulating portion 20 filling the step portion 12S of the teeth 12 can be reduced, and the cross-sectional area of the teeth 12 can be increased. In other words, magnetic saturation in the teeth 12 is less likely to occur, and iron loss can be reduced.

18 shows an example in which the step portion 12S of the tooth 12 has a shape that satisfies A > B, but the step portion 12S may have a shape that satisfies A < B. In this case, it is sufficient that the corners E1 to En of the intermediate step portions 12T ₁ to 12 _n are located closer to the side surface 12 a of the tooth 12 than the points V1 to Vn obtained by equally dividing the imaginary curved surface G into (n+1).

Next, a description will be given of the shortest distance between intermediate step portions 12T ₁ to 12 _n of teeth 12 and third surface 203 of insulating portion 20. As described in the first embodiment with reference to FIG. 10 , the force acting on insulating portion 20 in the winding process of winding 30 is large on first surface 201 and small on second surface 202.

Therefore, it is desirable that the shortest distance between the intermediate step portions 12T ₁ to 12 _n of the teeth 12 and the third surface 203 of the insulating portion 20 is larger the closer it is to the first surface 201 (i.e., closer to the end surfaces 12e of the teeth 12) and smaller the closer it is to the second surface 202 (i.e., closer to the side surfaces 12a of the teeth 12).

19 is a diagram for explaining the shortest distance between the intermediate step portions _12T1 , _12T2 and the third surface 203 of the insulating portion 20 when two intermediate step portions _12T1 , _12T2 are provided in the step portion 12S. The shortest distance T3 between the intermediate step portion _12T1 (also referred to as the first intermediate step portion) and the third surface 203 is set to be larger than the shortest distance T4 between the intermediate step portion _12T2 (also referred to as the second intermediate step portion) and the third surface 203.

Since a greater force acts between intermediate step portion _12T1 and the third surface 203 of insulating portion 20 than between intermediate step portion _12T2 and the third surface 203 of insulating portion 20, the shortest distances T3, T4 satisfy T3 > T4, so that the cross-sectional area of teeth 12 can be increased while preventing damage to insulating portion 20.

Except for the points mentioned above, the electric motor of the second embodiment is configured similarly to the electric motor 100 of the first embodiment.

As described above, in embodiment 2, the step portion 12S of the tooth 12 has a shape that satisfies A>B, and the corners E1 to En of the multiple intermediate step portions 12T ₁ to 12 _n formed in the step portion 12S are located closer to the end face 12e of the tooth 12 than the points V1 to Vn obtained by equally dividing the imaginary curved surface G into (n+1) parts.

This configuration allows the cross-sectional area of the teeth 12 to be increased, suppressing magnetic saturation in the teeth 12 and reducing iron loss.

Embodiment 3.
Next, a description will be given of embodiment 3. In embodiment 1, the step portions 12S are formed at both axial ends of the stator 1. In contrast, in embodiment 3, the step portion 12S is formed only at one axial end of the stator 1.

FIG. 20 is a diagram showing the relationship between the stator core 10 and rotor core 50 of the electric motor of embodiment 3. In FIG. 20, the axial direction toward the compression mechanism 9 of the compressor 8 (FIG. 26) is shown as the -Z direction, and the opposite direction is shown as the +Z direction.

The +Z end face 50e of the rotor core 50 is located further in the +Z direction than the +Z end face 10e of the stator core 10. The -Z end face 50e of the rotor core 50 is located further in the +Z direction than the -Z end face 10e of the stator core 10.

In other words, the rotor core 50 protrudes in the +Z direction from the stator core 10. That is, the axial center position of the rotor core 50 is displaced in the +Z direction from the axial center position of the stator core 10.

As a result, a magnetic attraction force acts between the stator core 10 and the rotor core 50 in a direction that brings the center positions of both closer together in the axial direction. This magnetic attraction force urges the rotor 5 in the -Z direction, i.e., toward the compression mechanism 9, suppressing vibration of the rotor 5.

In the third embodiment, the +Z-direction end of the tooth 12 does not have a step portion 12S. On the other hand, the -Z-direction end of the tooth 12 has a step portion 12S and also has an intermediate step portion 12T (Figure 7). The configuration of the step portion 12S and the intermediate step portion 12T is as described in the first embodiment.

The axial length of the step portion 12S of the teeth 12 is height A, as explained in the first embodiment. The axial length of the area of the core region R1, which is at height A in the axial direction from the -Z end face 10e of the stator core 10, that faces the rotor core 50 is L1. Core region R1 is also referred to as the first region, and core region R2 is also referred to as the second region.

Similarly, the axial length of the core region R2, which is at height A in the axial direction from the end face 10e of the stator core 10 in the +Z direction, that faces the rotor core 50 is defined as L2.

In the core regions R1, R2 of the stator core 10, the lengths L1, L2 of the facing region with the rotor core 50 satisfy L1 < L2. In other words, when the core regions R1, R2 of the same height A are defined at both axial ends of the stator core 10, the step portions 12S of the teeth 12 are formed on the side where the proportion of the facing region with the rotor core 50 in the core regions R1, R2 is smaller.

In core region R2 of stator core 10, the proportion of the area facing rotor core 50 is large, so more magnetic flux flows in from rotor 5. Therefore, if step portion 12S is provided in core region R2 of teeth 12, magnetic saturation is more likely to occur, and iron loss may increase.

In view of this, in the third embodiment, the teeth 12 are provided with step portions 12S and intermediate step portions 12T only in the core region R1 where the inflow magnetic flux from the rotor core 50 is small. In other words, the teeth 12 are provided with step portions 12S and intermediate step portions 12T only at the end of the stator core 10 in the -Z direction. In addition, although not shown in the figure, the step portions 11S of the core back 11 and the step portions 13S of the tooth tips 13 are also provided only at the end of the stator core 10 in the -Z direction.

Except for the points mentioned above, the electric motor of the third embodiment is configured similarly to the electric motor 100 of the first embodiment.

As described above, in the third embodiment, the teeth 12 are provided with a step portion 12S and an intermediate step portion 12T at the end of the stator core 10 in the axial direction that faces the rotor core 50 in a smaller area when the axial length is the same. This makes it possible to reduce the circumferential length of the windings 30 and reduce copper loss while suppressing magnetic saturation in the teeth 12.

Variant examples.
21 is a diagram showing the relationship between stator core 10 and rotor core 50 in a modification of embodiment 3. In this modification, rotor core 50 protrudes from stator core 10 on both axial sides, i.e., in the +Z and −Z directions. However, the amount of protrusion Z2 of rotor core 50 in the +Z direction is greater than the amount of protrusion Z1 in the −Z direction.

In this manner, the rotor core 50 protrudes from the stator core 10 on both axial sides, thereby shortening the axial length of the stator core 10 and reducing the material costs of the stator core 10.

Meanwhile, magnetic flux also flows into the stator core 10 from the protruding portion of the rotor core 50. Therefore, more magnetic flux from the rotor core 50 flows into the +Z end of the stator core 10 compared to the -Z end of the stator core 10.

In this modified example, the teeth 12 are provided with step portions 12S and intermediate step portions 12T only at the -Z direction end of the stator core 10 where the inflow of magnetic flux from the rotor core 50 is small. In addition, although not shown in the figure, the step portions 11S of the core back 11 and the step portions 13S of the tooth tips 13 are also provided only at the -Z direction end of the stator core 10.

In this modified example, as in the third embodiment, it is possible to reduce the circumferential length of the winding 30 and reduce copper loss while suppressing magnetic saturation in the teeth 12.

Embodiment 4.
Next, a fourth embodiment will be described. Fig. 22 is a perspective view showing a split core 15 and an insulator 40 according to the fourth embodiment. In the fourth embodiment, the insulator 40 is provided on the end face 10e of the split core 15, and an insulating film 70 (Fig. 23) is provided on the side face 12a of the tooth 12.

The shape of the teeth 12 of the split core 15 is as described in the first embodiment. However, the core back 11 has a fitting hole 101 formed therein. It is preferable that the core back 11 of each split core 15 has two or more fitting holes 101. It is even more preferable that each fitting hole 101 is formed on the outer periphery of the core back 11.

In the example shown in FIG. 22, two fitting holes 101 are formed on both circumferential sides of the teeth 12. More specifically, the fitting holes 101 are formed adjacent to the radially inner sides of the two notches 18b formed in the core back 11.

The insulator 40 is made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP). The insulator 40 has a body portion 41 attached to the teeth 12, a wall portion 42 attached to the core back 11, and a flange portion 43 attached to the tooth tip portion 13.

The body portion 41 is provided on the end surface 12e of the tooth 12. The body portion 41 also has an engagement portion 41a (FIG. 23) that engages with the step portion 12S of the tooth 12. The body portion 41 has a first surface 401 facing the axial direction, a second surface 402 facing the slot 14, and a third surface 403 extending from the first surface 401 to the second surface 402.

The wall portion 42 is provided on the end surface 11e of the core back 11. The wall portion 42 also has an engagement portion 42a that engages with the step portion 11S of the core back 11. Two pins 44 are formed as fitting portions on the side of the wall portion 42 facing the core back 11. The pins 44 engage with fitting holes 101 formed in the core back 11.

The flange portion 43 is provided on the end face 13e of the tooth tip portion 13. The flange portion 43 also has an engagement portion 43a that engages with the step portion 13S of the tooth tip portion 13.

The insulator 40 is fixed to the split core 15 by fitting the pin 44 of the wall portion 42 into the fitting hole 101 of the core back 11. The winding 30 is wound around the body portion 41 of the insulator 40. The wall portion 42 and the flange portion 43 guide the winding 30 wound around the body portion 41.

Because force is applied to the insulator 40 when the winding 30 is wound, it is necessary to fix the insulator 40 to prevent it from shifting position relative to the split core 15. If sufficient fixing force is to be obtained only by the engagement between the engagement portion 41a of the insulator 40 and the step portion 12S of the tooth 12, the step portion 12S of the tooth 12 must be made larger, which reduces the cross-sectional area of the tooth 12.

For this reason, the insulator 40 is provided with a pin 44 as a fitting portion. However, if the insulator 40 only has one pin 44, it is difficult to resist the force in the torsional direction of the insulator 40 (i.e., the force that tilts the extension direction of the body portion 41 relative to the extension direction of the teeth 12).

In this fourth embodiment, as described above, two pins 44 are provided on the insulator 40 (more specifically, the wall portion 42). This allows the insulator 40 to be fixed to the split core 15 with sufficient strength, and prevents misalignment when winding the winding 30.

In addition, the fitting holes 101 that fit onto the pins 44 of the insulator 40 are formed on the outer periphery of the core back 11. In the core back 11, the flow of magnetic flux is greater on the inner periphery closer to the slots 14. Therefore, if the fitting holes 101 are formed on the outer periphery of the core back 11, there is less effect on the flow of magnetic flux. Therefore, it is possible to suppress an increase in iron loss in the core back 11.

In FIG. 22, the fitting hole 101 is formed radially inside the notch 18b of the core back 11, but the notch 18b may be used as the fitting hole. Also, the notch 18b may be formed in another location on the outer periphery of the core back 11. However, since the

protrusions

17a, 17b of the core back 11 are abutment parts that fit into the shell of the compressor, etc., it is preferable to form the fitting hole 101 somewhere other than these

protrusions

17a, 17b.

FIG. 23 is a cross-sectional view of the teeth 12, insulator 40, and insulating film 70 of embodiment 4, taken along a plane perpendicular to the extension direction of the teeth 12.

The insulating film 70 is, for example, a film made of a resin such as polyethylene terephthalate (PET). The thickness of the insulating film 70 is, for example, 0.35 mm.

The insulating film 70 is provided so as to cover the inner peripheral surface 11a (FIG. 22) of the core back 11, the side surface 12a of the teeth 12, and the outer surface 13a (FIG. 22) of the tooth tip portion 13. In other words, the insulating film 70 is provided so as to cover the inner surface of the slot 14.

The insulating film 70 not only covers the side surface 12a of the tooth 12, but also extends to cover the second surface 402 of the insulator 40. In other words, the insulating film 70 protrudes further in the axial direction from the side surface 12a of the tooth 12.

In the insulator 40, the third surface 403 protrudes toward the slot 14 side more than the second surface 402. In other words, the insulator 40 is formed with a canopy-shaped cover portion 405 that covers the end surface of the insulating film 70.

In the fourth embodiment, since the insulating portion is made up of the insulator 40 and the insulating film 70, it is necessary to ensure an insulation distance from the teeth 12 to the windings 30. The insulation distance is the shortest distance between conductors measured along the surface of the insulator, and is also called the creepage distance.

The amount of axial protrusion of the insulating film 70 from the bottom surface 12c of the step portion 12S is defined as H. The amount of protrusion H of the insulating film 70 is set to be equal to or greater than the creepage distance from the teeth 12 to the windings 30. The insulation distance is, for example, 2.5 mm.

In the fourth embodiment, the teeth 12 have step portions 12S, and a portion of the insulating film 70 extends along the second surface 402 of the insulator 40, so that the axial protrusion amount H of the insulating film 70 can be increased and an insulating distance can be ensured without increasing the size of the insulator 40. This allows the circumferential length of the winding 30 to be shortened, and copper loss to be reduced.

Except for the points mentioned above, the electric motor of the fourth embodiment is configured similarly to the electric motor 100 of the first embodiment.

As described above, in the fourth embodiment, an insulator 40 is provided for each tooth 12, two or more pins 44 are provided as fitting portions on each insulator 40, and two or more fitting holes 101 into which the pins 44 fit are formed in the core back 11. Therefore, it is possible to suppress misalignment of the insulator 40 due to an external force acting when winding the winding 30.

In addition, since the fitting holes 101 are formed at locations on the outer periphery of the core back 11 other than the contact area with the shell, the effect of the fitting holes 101 on the magnetic flux inside the core back 11 can be reduced.

In addition, an insulating film 70 is provided to cover the side surface 12a of the teeth 12, so the insulator 40 and the insulating film 70 can insulate the winding 30 from the stator core 10.

In particular, since the insulating film 70 extends to cover not only the side surface 12a of the teeth 12 but also a portion of the insulator 40 (more specifically, the second surface 402), a sufficient insulating distance can be ensured without increasing the size of the insulator 40.

Variant examples.
Fig. 24 is a cross-sectional view showing a tooth 12, an insulator 40, and an insulating film 70 according to a modification of the fourth embodiment. Fig. 24 also shows a winding 30 wound around the tooth 12.

In embodiment 4, the width W4 of the axial center portion 125 of the tooth 12 is wider than the width of the other portions of the tooth 12 (i.e., the widths W1, W2, and W3 described in embodiment 1).

The insulating film 70 is flexible, so it can be curved and positioned along the side of the central portion 125 of the tooth 12 and along the side surfaces 12a on both axial sides of the central portion 125.

In the configurations described in the above-mentioned embodiments 1 to 4, the gap between the side surface 12a of the teeth 12 and the winding 30 can be minimized by suppressing the winding bulge of the winding 30. However, since the winding bulge of the winding 30 cannot be reduced to zero, a small gap may occur between the side surface 12a of the teeth 12 and the winding 30 in the axial center of the teeth 12.

In a modification of the fourth embodiment, the width W4 of the axial center portion 125 of the teeth 12 is made wider than the width T1 of the other portions of the teeth 12, taking into account the amount of swelling of the windings 30. This makes it possible to increase the cross-sectional area of the teeth 12 by utilizing the space created by the swelling of the windings 30. This makes it possible to suppress magnetic saturation in the teeth 12 and reduce iron loss.

In the above-described first to fourth embodiments and each of the modified examples, the third surface 203 (403) of the insulating portion 20 (40) is a curved surface. However, the third surface 203 (403) of the insulating portion 20 (40) is not limited to a curved surface, and may be formed of at least one inclined surface.

For example, the insulating portion 20 shown in FIG. 25 has a first surface 201 facing the end surface 12e of the tooth 12, a second surface 202 facing the side surface 12a of the tooth 12, and a third surface 205 extending from the first surface 201 to the second surface 202. The third surface 205 is formed by a combination of a first inclined surface 211 and a second inclined surface 212.

The connection between the first inclined surface 211 and the second inclined surface 212 faces the corner E of the intermediate step portion 12T. Note that the inclined surface refers to a plane that is inclined with respect to the end surface 12e and the side surface 12a of the tooth 12.

FIG. 25 shows the third surface 205 formed by two inclined surfaces, but the third surface 205 may be formed by a single inclined surface or a combination of three or more inclined surfaces.

Embodiments 1 to 4 and the various modifications can be combined as appropriate. For example, as described in embodiment 3, a step 12S provided at only one axial end of a tooth 12 may be provided with two or more intermediate steps 12T as described in embodiment 2. Alternatively, a tooth 12 having two or more intermediate steps 12T provided at a step 12S as described in embodiment 2 may be combined with an insulator 40 and insulating film 70 as described in embodiment 4.

<Compressor>
Next, the compressor 8 using the electric motor 100 will be described. Fig. 26 is a cross-sectional view showing the configuration of the compressor 8. The compressor 8 is a rotary compressor here, and has a shell 80, a compression mechanism 9 disposed in the shell 80, an electric motor 100 that drives the compression mechanism 9, and a shaft 90 that connects the electric motor 100 and the compression mechanism 9 so as to be capable of transmitting power. The shaft 90 is the shaft 90 shown in Fig. 1 etc., and is fitted into the central hole 53 of the rotor 5 of the electric motor 100.

The shell 80 is a sealed container made of, for example, steel plate, and covers the electric motor 100 and the compression mechanism 9. The shell 80 has an upper shell 80a and a lower shell 80b. The upper shell 80a is fitted with a glass terminal 81 as a terminal part for supplying power to the electric motor 100 from outside the compressor 8, and a discharge pipe 85 for discharging the refrigerant compressed in the compressor 8 to the outside. The lower shell 80b houses the electric motor 100 and the compression mechanism 9.

The compression mechanism 9 has an annular first cylinder 91 and a second cylinder 92 along the shaft 90. The first cylinder 91 and the second cylinder 92 are fixed to the inner periphery of the lower shell 80b. An annular first piston 93 is disposed on the inner periphery of the first cylinder 91, and an annular second piston 94 is disposed on the inner periphery of the second cylinder 92. The first piston 93 and the second piston 94 are rotary pistons that rotate together with the shaft 90.

A partition plate 97 is provided between the first cylinder 91 and the second cylinder 92. The partition plate 97 is a disk-shaped member with a through hole in the center. The cylinder chambers of the first cylinder 91 and the second cylinder 92 are provided with vanes (not shown) that divide the cylinder chambers into an intake side and a compression side. The first cylinder 91, the second cylinder 92, and the partition plate 97 are fixed together by bolts 98.

An upper frame 95 is disposed above the first cylinder 91 so as to close the upper side of the cylinder chamber of the first cylinder 91. A lower frame 96 is disposed below the second cylinder 92 so as to close the lower side of the cylinder chamber of the second cylinder 92. The upper frame 95 and the lower frame 96 rotatably support the shaft 90.

Refrigeration oil (not shown) that lubricates each sliding part of the compression mechanism 9 is stored in the bottom of the lower shell 80b of the shell 80. The refrigeration oil rises through a hole 90a formed in the axial direction inside the shaft 90, and is supplied to each sliding part from oil supply holes 90b formed in multiple places on the shaft 90.

The stator 1 of the electric motor 100 is attached to the inside of the shell 80 by shrink fitting. Electricity is supplied to the windings 30 of the stator 1 from glass terminals 81 attached to the upper shell 80a. A shaft 90 is fixed in the central hole 53 of the rotor 5 (Figure 1).

An accumulator 87 that stores refrigerant gas is attached to the shell 80. The accumulator 87 is held, for example, by a holding portion 80c provided on the outside of the lower shell 80b. A pair of

suction pipes

88, 89 are attached to the shell 80, and refrigerant gas is supplied from the accumulator 87 to the

cylinders

91, 92 via the

suction pipes

88, 89.

As a refrigerant, for example, R410A, R407C, or R22, etc. may be used, but from the perspective of preventing global warming, it is desirable to use a refrigerant with a low GWP (global warming potential). For example, the following refrigerants can be used as low GWP refrigerants.

(1) First, a halogenated hydrocarbon having a carbon double bond in its composition, such as HFO (Hydro-Fluoro-Orefin)-1234yf (CF ₃ CF═CH ₂ ), can be used. The GWP of HFO-1234yf is 4.
(2) Hydrocarbons having carbon double bonds in their composition, such as R1270 (propylene), may also be used. R1270 has a GWP of 3, which is lower than HFO-1234yf, but is more flammable than HFO-1234yf.
(3) Also, a mixture containing at least one of a halogenated hydrocarbon having a carbon-carbon double bond in its composition or a hydrocarbon having a carbon-carbon double bond in its composition, for example, a mixture of HFO-1234yf and R32 may be used. The above-mentioned HFO-1234yf is a low-pressure refrigerant and tends to cause large pressure loss, which may lead to a decrease in the performance of the refrigeration cycle (especially the evaporator). For this reason, it is practically preferable to use a mixture of HFO-1234yf and R32 or R41, which are refrigerants with a higher pressure than HFO-1234yf.

The basic operation of the compressor 8 is as follows. Refrigerant gas supplied from the accumulator 87 is supplied to each cylinder chamber of the first cylinder 91 and the second cylinder 92 through the

suction pipes

88, 89. When the electric motor 100 is driven and the rotor 5 rotates, the shaft 90 rotates together with the rotor 5. Then, the first piston 93 and the second piston 94 fitted to the shaft 90 rotate eccentrically in each cylinder chamber, compressing the refrigerant in each cylinder chamber. The compressed refrigerant passes through the

holes

57, 58 of the rotor 5 (Figure 1), rises inside the shell 80, and is discharged to the outside from the discharge pipe 85.

The compressor in which the electric motor 100 is used is not limited to a rotary compressor, but may be, for example, a scroll compressor.

The electric motor 100 of each embodiment has high motor efficiency due to reduced copper loss and iron loss. This improves the operating efficiency of the compressor 8. In addition, the manufacturing cost of the electric motor 100 is reduced by suppressing the swelling of the windings 30, and therefore the manufacturing cost of the compressor 8 can also be reduced.

<Refrigeration cycle device>
Next, a refrigeration cycle apparatus 300 having the compressor 8 shown in Fig. 26 will be described. Fig. 27 is a diagram showing the refrigeration cycle apparatus 300. The refrigeration cycle apparatus 300 is, for example, an air conditioner, but is not limited thereto and may be, for example, a refrigerator.

The refrigeration cycle device 300 shown in FIG. 27 includes a compressor 301, a condenser 302 that condenses the refrigerant, a pressure reducing device 303 that reduces the pressure of the refrigerant, and an evaporator 304 that evaporates the refrigerant. The compressor 301, the condenser 302, and the pressure reducing device 303 are provided in the outdoor unit 310, and the evaporator 304 is provided in the indoor unit 320.

Compressor 301, condenser 302, pressure reducing device 303, and evaporator 304 are connected by refrigerant piping 307 to form a refrigerant circuit. Compressor 301 is composed of compressor 8 shown in FIG. 26. Refrigeration cycle device 300 also includes outdoor blower 305 facing condenser 302, and indoor blower 306 facing evaporator 304.

The operation of the refrigeration cycle device 300 is as follows. The compressor 301 compresses the sucked refrigerant and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 302 exchanges heat between the refrigerant sent out from the compressor 301 and the outdoor air sent by the outdoor blower 305, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 303 expands the liquid refrigerant sent out from the condenser 302, and sends it out as low-temperature, low-pressure liquid refrigerant.

The evaporator 304 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 303 and the indoor air, evaporating the refrigerant and sending it out as refrigerant gas. The air from which the heat has been removed by the evaporator 304 is supplied to the room by the indoor blower 306.

The electric motor 100 described in each embodiment can be applied to the compressor 301 of the refrigeration cycle device 300, so the operating efficiency of the refrigeration cycle device 300 can be improved.

The above describes a preferred embodiment in detail, but the present disclosure is not limited to the above embodiment, and various improvements and modifications can be made.

1 stator, 5 rotor, 8 compressor, 9 compression mechanism, 10 stator core, 10e end face, 11 core back, 11S step portion, 11T intermediate stage portion, 12 teeth, 12E elliptical arc, 12S step portion, 12T intermediate stage portion, 12T1 intermediate stage portion (first intermediate stage portion), 12T2 intermediate stage portion (second intermediate stage portion), 12T3 intermediate stage portion, 12a Side, 12b wall, 12c bottom, 12e end, 13 tooth tip, 13S step, 13T intermediate step, 14 slot, 15 split core, 17a, 17b convex (contact portion), 18a groove, 18b notch, 20 insulating portion, 21 body, 22 wall, 23 flange, 30 winding, 40 insulator, 41 body, 42 wall , 43 flange portion, 44 pin (fitting portion), 50 rotor core, 50e end face, 51 magnet insertion hole, 52 flux barrier, 53 center hole, 60 permanent magnet, 70 insulating film, 80 shell, 90 shaft, 100 electric motor, 101 fitting hole, 121 first surface of intermediate stage portion, 122 second surface of intermediate stage portion, 125 center of teeth, 201, 401: first surface of insulating part; 202, 402: second surface of insulating part; 203, 205, 403: third surface of insulating part; 211: first inclined surface; 212: second inclined surface; 300: refrigeration cycle device; 301: compressor; 302: condenser; 303: pressure reducing device; 304: evaporator; 401: first surface; 402: second surface; 403: third surface; 405: cover part.

Claims

a stator core including an annular core back, teeth extending radially inward from the core back, and slots adjacent to the teeth in a circumferential direction of the core back;
An insulating portion provided on the tooth;
a winding wound around the tooth via the insulating portion,
The teeth each have an end surface that defines an end of the tooth in the axial direction of the stator core, a side surface facing the slot, a step portion formed between the end surface and the side surface, and an intermediate step portion formed in the step portion,
When the width of the teeth is defined in a direction perpendicular to both the axial direction and the extension direction of the teeth, the teeth have widths W1, W2, and W3 depending on their positions in the axial direction, and W1>W2>W3 holds true.
The insulating portion has a first surface covering the end surface of the tooth, a second surface facing the slot, and a third surface which is a curved surface or an inclined surface extending from the first surface to the second surface,
A stator, wherein a shortest distance T1 from the end face of the tooth to the first surface of the insulating portion and a shortest distance T3 from the intermediate step portion to the third surface of the insulating portion satisfy T1>T3.
2. The stator according to claim 1, wherein a shortest distance T3 from the intermediate step portion to the third surface of the insulating portion and a shortest distance T2 from the side surface of the tooth to the second surface of the insulating portion satisfy T3>T2.
In a cross section perpendicular to the extending direction of the teeth, a boundary between the first surface and the third surface is defined as point P, a boundary between the second surface and the third surface is defined as point Q, and an intersection point U is defined between a first straight line that passes through point P and is parallel to the axial direction and a second straight line that passes through point Q and is perpendicular to the axial direction.
a height A of the step portion in the axial direction, a width B of the step portion in a direction perpendicular to both the axial direction and the extending direction of the teeth, a distance D1 from a point P to an intersection point U, and a distance D2 from a point Q to the intersection point U.
3. The stator according to claim 1, wherein D1≦A and D2≦B are satisfied.
The stator according to claim 3 , wherein the height A and the width B of the step portion satisfy A≧B.
The height A of the step portion with respect to the axial length L1 of the tooth is,
A/L1≦0.141
A stator according to claim 3 or 4, which satisfies the above requirements.
The stator according to claim 1 , wherein the step portion of the tooth is formed with n (n is an integer of 2 or more) intermediate step portions.
a height A of the step portion in the axial direction and a width B of the step portion in a direction perpendicular to both the axial direction and the extending direction of the teeth satisfy A>B,
A virtual curved surface is defined by translating the third surface of the insulating portion so as to pass through a corner of at least one of the n number of intermediate step portions, and n division points are defined to equally divide the virtual curved surface into (n+1).
The stator according to claim 6 , wherein each of the n intermediate step portions is disposed closer to the end face of the tooth than a corresponding division point.
One of the n intermediate stages is a first intermediate stage;
When an intermediate step portion closer to the side surface of the tooth than the first intermediate step portion is defined as a second intermediate step portion,
The stator according to claim 7 , wherein a shortest distance from the first intermediate stage to the third surface of the insulating portion is longer than a shortest distance from the second intermediate stage to the third surface of the insulating portion.
The stator according to claim 1 , wherein the insulating portion includes an insulator disposed on the end surface of the tooth and an insulating film covering the side surface of the tooth.
the insulator has two or more fitting portions protruding toward the stator core,
The stator according to claim 9 , wherein the stator core has two or more holes into which the two or more fitting portions fit.
The stator core is fitted into a cylindrical shell,
The stator according to claim 10 , wherein the two or more holes are formed in an outer periphery of the stator core other than a portion in contact with the shell.
The stator according to claim 9 , wherein the insulating film is provided to cover the side surfaces of the teeth and to cover the second surface of the insulating portion.
The stator according to claim 12 , wherein the insulator has an opposing portion that faces an end portion of the insulating film in the axial direction.
The stator according to claim 9 , wherein a width of a central portion of each of the teeth in the axial direction is greater than a width of other portions of each of the teeth.
The stator core faces the rotor core,
the stator core has a first region having a height A at one end in the axial direction and a second region having a height A at the other end in the axial direction;
a length of a range of the first region facing the rotor core is shorter than a length of a range of the second region facing the rotor core,
The stator according to claim 1 , wherein the step portion is provided only in the first region of the stator core.
The stator core faces the rotor core,
The rotor core protrudes from one end of the stator core in the axial direction by a distance Z1, and protrudes from the other end of the stator core in the axial direction by a distance Z2,
Distance Z1 is shorter than distance Z2,
The stator according to claim 1 , wherein the step portion is provided only on the one end side of the stator core.
A stator according to any one of claims 1 to 16,
and a rotor disposed inside the stator.
An electric motor according to claim 17;
a compression mechanism driven by the electric motor.
A refrigeration cycle apparatus comprising: the compressor according to claim 18; a condenser; a pressure reducing device; and an evaporator.