Stator, electric motor, compressor, and refrigeration cycle equipment

Abstract

This stator core has an annular core back, a tooth extending from the core back to the inside in the radial direction, and a slot 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 facing in the axial direction of the stator core, a side surface facing a slot, and a step portion formed between the end surface and the side surface. The insulating portion has a first surface covering the end surface of the tooth, a second surface facing the slot, and a third surface that is a curved surface or a sloped surface extending from the first surface to the second surface. In a cross-section orthogonal to the extending direction of the tooth, the boundary between the first surface and the third surface is denoted by point P, the boundary between the second surface and the third surface is denoted by point Q, and the intersection of a first line that passes through the point P and is parallel with the axial direction and a second line that passes through the point Q and is orthogonal to the axial direction is denoted by U. The height A of the step portion in the axial direction, the width B of the step portion in a direction orthogonal to the axial direction, the distance D1 from the point P to the intersection U, and the distance D2 from the point Q to the intersection U satisfy the relationships of D1 ≤ A and D2 ≤ B.

Description

Technical Field

[0001] The present disclosure relates to a stator, an electric motor, a compressor, and a refrigeration cycle device.

Background Art

[0002] The stator of an electric motor has a stator core having teeth, windings wound around the teeth, and an insulating portion interposed between the teeth and the windings. In order to shorten the circumferential length of the windings, it is also known to provide stepped portions at the axial ends of the teeth (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a stepped portion is provided on the teeth, a locally thin portion occurs in the insulating portion covering the teeth, and the insulating portion is likely to be damaged. If the thickness of the insulating portion is increased to prevent damage, the circumferential length of the windings becomes longer.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to shorten the circumferential length of the windings.

Means for Solving the Problems

[0006] The stator according to the present disclosure A stator used in conjunction with a rotor, has 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 And, opposite the rotor core of the rotor a stator core, an insulating portion provided on the teeth, and windings wound around the teeth via the insulating portion. The stator core has a first region of height A at one end in the axial direction and a second region of height A at the other end in the axial direction. The length of the portion of the first region facing the rotor core is shorter than the length of the portion of the second region facing the rotor core. In the first region of the stator core, and only in the first region, the teeth have an end face facing the axial direction, a side surface facing the slot, and a stepped portion formed between the end face and the side surface.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 or inclined surface extending from the first surface to the second surface. In a cross section perpendicular to the extending direction of the teeth, let P be the boundary between the first surface and the third surface, and let Q be the boundary between the second surface and the third surface. Let U be the intersection of a first straight line passing through point P and parallel to the axial direction and a second straight line passing through point Q and perpendicular to the axial direction. Then, the axial height A of the stepped portion, the width B of the stepped portion in the direction perpendicular to the axial direction, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U satisfy D1 ≤ A and D2 ≤ B. The stator according to this disclosure is also a stator used in conjunction with a rotor, and comprises 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, a stator core facing the rotor core of the rotor, an insulating portion provided on the teeth, and windings wound around the teeth via the insulating portion. The rotor core protrudes from one end of the stator core by a distance Z1 in the axial direction of the stator core and from the other end of the stator core by a distance Z2 in the axial direction of the stator core. Distance Z1 is shorter than distance Z2. On one end of the stator core, and only on the side of the other end, the teeth have an axially oriented end face, a side surface facing the slot, and a stepped portion formed between the end face and the side surface. The insulating portion has a first surface covering the end face of the teeth, a second surface facing the slot, and a third surface which is a curved or inclined surface extending from the first surface to the second surface. In a cross-section perpendicular to the extension direction of the teeth, let P be the boundary between the first and third surfaces, and let Q be the boundary between the second and third surfaces. Let U be the intersection of a first straight line passing through point P and parallel to the axial direction and a second straight line passing through point Q and perpendicular to the axial direction. Then, the axial height A of the stepped portion, the width B of the stepped portion in the direction perpendicular to the axial direction, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U satisfy D1 ≤ A and D2 ≤ B. [Effects of the Invention]

[0007] In this disclosure, the height A and width B of the stepped portion, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U satisfy D1 ≤ A and D2 ≤ B, so that point P does not face the end face of the teeth and point Q does not face the side surface of the teeth. Therefore, stress concentration in the insulating portion can be suppressed. As a result, the thickness of the insulating portion can be reduced and the circumference of the winding can be shortened. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing the electric motor of Embodiment 1. [Figure 2] This diagram shows the axial positional relationship between the stator core and the rotor core in Embodiment 1. [Figure 3] This is a plan view showing the stator core of Embodiment 1. [Figure 4] This is a perspective view showing the divided core of Embodiment 1. [Figure 5] This is a perspective view showing the divided core and insulating portion of Embodiment 1. [Figure 6] This is a cross-sectional view showing the teeth and insulating portion of Embodiment 1. [Figure 7] This is a cross-sectional view showing another example of the teeth and insulating portion of Embodiment 1. [Figure 8]It is a diagram showing an enlarged view of the step portion of the teeth in Embodiment 1. [Figure 9] It is a cross-sectional view (A) showing the teeth and insulation part of Comparative Example 1, a cross-sectional view (B) showing the teeth and insulation part of Comparative Example 2, and a diagram (C) showing an enlarged view of the step portion of the teeth in Comparative Example 2. [Figure 10] It is a graph showing the relationship between the dimensional ratio A / B of the step portion in Embodiment 1 and the torque constant. [Figure 11] It is a graph showing the relationship between the ratio A / L1 of the height A of the step portion to the length L1 of the teeth in Embodiment 1 and the loss change rate. [Figure 12] It is a diagram showing the axial positional relationship between the stator core and the rotor core in Embodiment 2. [Figure 13] It is a cross-sectional view showing the teeth and insulation part in Embodiment 2. <000007*5*> [Figure 14] It is a diagram showing another example of the axial positional relationship between the stator core and the rotor core in Embodiment 2. [Figure 15] It is a perspective view showing the split core and insulation part in Embodiment 3. [Figure 16] It is a cross-sectional view showing the teeth and insulation part in Embodiment 3. <000*0081*> [Figure 17] It is a cross-sectional view showing the teeth and insulation part in Comparative Example 3. [Figure 18] It is a longitudinal cross-sectional view showing a compressor to which the motors of each embodiment can be applied. [Figure 19] It is a diagram showing a refrigeration cycle device to which the compressor in FIG. 18 can be applied.

Embodiments for Carrying Out the Invention

[0009] Embodiment 1. <Configuration of the motor> ]>First, Embodiment 1 will be described. FIG. 1 is a cross-sectional view showing the motor 100 of Embodiment 1. The motor 100 shown in FIG. 1 is a permanent magnet embedded type motor and is used, for example, in a compressor 8 (FIG. 18).

[0010] It should be noted that there are some possible typos in the original text, such as the repeated " " and " " which are maintained as they are in the translation. Also, the reference numbers seem to be in a rather disordered format in the original, but are translated exactly as provided.The electric motor 100 has a rotor 5 having a shaft 65 which is the rotating shaft, and a stator 1 that surrounds the rotor 5. An air gap of, for example, 0.3 to 1.0 mm is formed between the stator 1 and the rotor 5. The stator 1 is incorporated inside the cylindrical shell 80 of the compressor 8 (Figure 18), which will be described later.

[0011] In the following, the direction of the axis Ax, which is the rotation center of rotor 5, will be referred to as the "axial direction." The radial direction centered on axis Ax will be referred to as the "radial direction." The circumferential direction centered on axis Ax will be referred to as the "circumferential direction."

[0012] <Rotor Configuration> The rotor 5 has a cylindrical rotor core 50 centered on the axis Ax, and permanent magnets 60 attached to the rotor core 50. The rotor core 50 is made by laminating multiple electromagnetic steel sheets in the axial direction and fixing them together by crimping or the like.

[0013] The thickness of the electrical steel sheet is 0.1 to 0.7 mm. A central hole 53 is formed at the radial center of the rotor core 50. The shaft 65 is fixed to the central hole 53 of the rotor core 50 by shrink fitting, press fitting, or adhesive. The rotor core 50 has a circumferential outer circumference centered on the axis Ax.

[0014] Multiple magnet insertion holes 51 into which permanent magnets 60 are inserted are formed along the outer circumference of the rotor core 50. Each magnet insertion hole 51 corresponds to one magnetic pole. The circumferential center of a magnet insertion hole 51 corresponds to the pole center. An interpole portion is defined between adjacent magnet insertion holes 51. In this case, there are 6 magnet insertion holes 51. In other words, there are 6 poles. However, the number of poles is not limited to 6; it can be 2 or more.

[0015] The magnet insertion hole 51 extends linearly in a direction perpendicular to a straight 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 in a V-shape, for example.

[0016] A single permanent magnet 60 is placed in each magnet insertion hole 51. The permanent magnet 60 is flat, has width in the circumferential direction of the rotor core 50, and thickness in the radial direction. Each permanent magnet 60 is magnetized in the thickness direction.

[0017] The permanent magnets 60 are, for example, made of rare earth elements. Rare earth elements include, 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.

[0018] 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 circumference of the rotor core 50. The radial width of the thin-walled portion is set to be the same as, for example, the thickness of the electrical steel sheet.

[0019] A slit 54 is formed between the magnet insertion hole 51 and the outer circumference of the rotor core 50. The slit 54 is formed to regulate the flow of magnetic flux emitted from the permanent magnet 60. In this example, seven slits 54 are formed symmetrically with respect to the circumferential center of the magnet insertion hole 51. However, the number and arrangement of the slits 54 are not limited to the example described here. Also, the rotor core 50 does not necessarily have to have slits 54.

[0020] In the rotor core 50, holes 57 and 58 are formed radially inward from the magnet insertion hole 51. The holes 57 and 58 are used as air vents for refrigerant passage or holes for inserting jigs. The number of holes 57 and 58 is equal to 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 space between the poles. However, the number and arrangement of the holes 57 and 58 are not limited to the example described here. Also, the rotor core 50 does not necessarily have to have holes 57 and 58.

[0021] Furthermore, crimping portions 56 for fixing the electromagnetic steel sheets of the rotor core 50 are formed on the radially outer side of each hole 58. However, the arrangement of the crimping portions 56 is not limited to the example described here. Also, the electromagnetic steel sheets of the rotor core 50 may be fixed by methods other than crimping.

[0022] <Stator Configuration> The stator 1 has a stator core 10 that surrounds the rotor core 50 from the radially outer side, and windings 30 wrapped around the stator core 10. The stator core 10 is made by laminating multiple electrical steel sheets in the axial direction and fixing them by crimping or the like. The thickness of the electrical steel sheets is 0.1 to 0.7 mm.

[0023] The stator core 10 has an annular core back 11 centered on the axis Ax, and a plurality of teeth 12 extending radially inward from the core back 11. The teeth 12 are arranged at regular intervals in the circumferential direction. The number of teeth 12 is 9 in this case. However, the number of teeth 12 is not limited to 9; it can be 2 or more. Slots 14 are formed between adjacent teeth 12 in the circumferential direction. The number of slots 14 is the same as the number of teeth 12, which is 9.

[0024] The winding 30 is made of magnet wire and is wound in a concentrated manner around each tooth 12. The outer diameter, or 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.

[0025] The winding 30 is made of aluminum wire or copper wire. Aluminum wire is particularly preferable because it is softer than copper wire and can be tightly wound around the teeth 12. In addition, aluminum wire is cheaper than copper wire, which is advantageous for reducing manufacturing costs.

[0026] Figure 2 shows 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 in the same axial position. That is, the axial end faces 10e of the stator core 10 are in the same axial position as the axial end faces 50e of the rotor core 50.

[0027] Note that the axial positional relationship between the stator core 10 and the rotor core 50 is not limited to the example shown in Figure 2; it is sufficient if the axial center position of the stator core 10 and the axial center position of the rotor core 50 coincide. The case where the axial center position of the stator core 10 and the axial center position of the rotor core 50 are different will be explained in Embodiment 2.

[0028] Figure 3 is a plan view showing the stator core 10. The core back 11 has an inner circumferential surface 11a and an outer circumferential surface. The inner circumferential surface 11a of the core back 11 faces the slot 14. The outer circumferential surface of the core back 11 fits into the shell 80 of the compressor 8 (Figure 18).

[0029] As described above, the teeth 12 extend radially inward from the core back 11. The radial line passing through the circumferential center of each tooth 12 is called the tooth centerline T1. The teeth 12 have a pair of side surfaces 12a on both sides in the circumferential direction. The side surfaces 12a of the teeth 12 face the slot 14.

[0030] Each tooth 12 also has a tooth tip portion 13 facing the rotor 5 (Figure 1). The tooth tip portion 13 is wider in the circumferential direction than the rest of the tooth 12 and protrudes circumferentially from 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.

[0031] Although the tooth tip portion 13 is part of the tooth 12, its shape differs from the rest of the tooth 12, so the tooth tip portion 13 may sometimes be described separately from the rest of the tooth 12.

[0032] A stepped portion 12S is formed at the axial end of the tooth 12. The stepped portion 12S is formed on the side surface 12a 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.

[0033] A stepped portion 11S is formed at the axial end of the core back 11. The stepped portion 11S is formed on the inner circumferential 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.

[0034] A stepped portion 13S is formed at the axial end of the tooth tip portion 13. The stepped 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 than at the axial center.

[0035] Furthermore, the core back 11 has a dividing surface 15 that divides the stator core 10. The dividing surface 15 is formed at an intermediate position between two adjacent teeth 12 in the circumferential direction. The dividing surface 15 extends from the inner circumferential surface 11a to the outer circumferential surface of the core back 11.

[0036] The stator core 10 is divided by a dividing surface 15 into nine segmented cores 10A, each containing one tooth 12. In other words, the stator core 10 is composed of multiple segmented cores 10A combined together.

[0037] The divided cores 10A are joined together by welding or the like at the dividing surface 15. Alternatively, the divided cores 10A may be connected to each other by thin-walled portions formed on the outer circumference of the dividing surface 15.

[0038] Figure 4 is a perspective view showing the split core 10A. In Figure 4, the direction of axis Ax (Figure 1), i.e., the axial direction, is indicated by the arrow Z. The core back 11 has an end face 11e facing the axial direction. The teeth 12 have an end face 12e facing the axial direction. The tooth tip 13 has an end face 13e facing the axial direction.

[0039] These end faces 11e, 12e, and 13e lie on the same plane and correspond to the end face 10e of the stator core 10 shown in Figure 2. Furthermore, all of the end faces 11e, 12e, and 13e are planes perpendicular to the axial direction.

[0040] The stepped portion 12S of the tooth 12 is formed between the end face 12e and the side surface 12a of the tooth 12. The stepped portion 12S consists 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.

[0041] The stepped portion 11S of the core back 11 is formed between the end face 11e and the inner circumferential surface 11a of the core back 11. The stepped portion 11S consists 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.

[0042] The stepped portion 13S of the tooth tip portion 13 is formed between the end face 13e and the outer surface 13a of the tooth tip portion 13. The stepped portion 13S consists 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.

[0043] The bottom surfaces 11c, 12c, and 13c of the stepped sections 11S, 12S, and 13S are located on the same plane. Therefore, the axial height (height A, described later) of the stepped sections 11S, 12S, and 13S is the same.

[0044] The split core 10A is composed of a first electrical steel sheet 101 laminated in the axial center and second electrical steel sheets 102 laminated at both axial ends. Compared to the first electrical steel sheet 101, the second electrical steel sheet 102 has a narrower width for the core back 11, a narrower width for the teeth 12, and a narrower width for the protruding portion of the tooth tip 13.

[0045] Figure 5 is a perspective view showing the divided core 10A and the insulating part 20. The insulating part 20 is attached to the divided core 10A so as to cover the teeth 12 from both the axial and circumferential sides. The insulating part 20 is made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP).

[0046] The insulating portion 20 has a body portion 22 that covers the teeth 12, a wall portion 21 located radially outward of the body portion 22, and a flange portion 23 located radially inward of the body portion 22. The wall portion 21 and the flange portion 23 are radially opposite each other with the body portion 22 in between.

[0047] The wall portion 21 is provided so as to cover the inner circumferential surface 11a of the core back 11 and further protrudes on both sides in the axial direction. The wall portion 21 has an engaging portion 21a that engages with the stepped portion 11S of the core back 11.

[0048] The body portion 22 is provided so as to cover the end face 12e and side surface 12a (Figure 4) of the teeth 12. The body portion 22 has an engaging portion 22a (Figure 6) that engages with the stepped portion 12S (Figure 4) of the teeth 12.

[0049] The flange portion 23 is provided so as to cover the end face 13e (Figure 4) and outer surface 13a of the tooth tip portion 13. The flange portion 23 has an engaging portion 23a that engages with the stepped portion 13S of the tooth tip portion 13.

[0050] The winding 30 is wound around the body portion 22. The wall portion 21 and flange portion 23 guide the winding 30 wound around the body portion 22 from both radial sides.

[0051] The insulating portion 20 is formed, for example, by integrally molding resin with the divided core 10A. Alternatively, the insulating portion 20 may be a molded resin body attached to the divided core 10A.

[0052] Here, we will describe the integrally constructed insulating section 20, but it may also be composed of an insulator and an insulating film. This will be explained in Embodiment 3.

[0053] Figure 6 is a cross-sectional view of the teeth 12 and the insulating portion 20 in a plane perpendicular to the direction of extension of the teeth 12. The direction of extension of the teeth 12 refers to the direction of the radial line passing through the circumferential center of the teeth 12, i.e., the tooth centerline T1 (Figure 3).

[0054] The tooth 12 has an axial length L1, which is the distance between the two end faces 12e of the tooth 12. The tooth 12 also has a width W1 in its axial center and a width W2 at the axial end where the stepped portion 12S is formed. The width W1 is the distance between the two side faces 12a of the tooth 12, and the width W2 is the distance between the wall surfaces 12b of the two stepped portions 12S of the tooth 12. The relationship between widths W1 and W2 is W1 > W2.

[0055] The insulating portion 20 has a first surface 201 which is a plane covering the end face 12e of the teeth 12, a second surface 202 which is a plane 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.

[0056] The first surface 201 is a plane extending in a plane perpendicular to the axial direction and is opposite to the end face 12e of the tooth 12. The second surface 202 is a plane extending in a plane parallel to the axial direction and is opposite to the side surface 12a of the tooth 12.

[0057] The third surface 203 is a curved surface that curvely connects the first surface 201 and the second surface 202, or an inclined surface that linearly connects the first surface 201 and the second surface 202, in a plane perpendicular to the extension direction of the teeth 12. The following description will focus on the case where the third surface 203 is a curved surface, but it may also be an inclined surface.

[0058] Let the axial dimension of the stepped portion 12S be the height A. This height A corresponds to the distance from the bottom surface 12c of the stepped portion 12S to the end surface 12e of the teeth 12.

[0059] On a plane perpendicular to the extending direction of the teeth 12, the dimension of the stepped portion 12S in the direction perpendicular to the axial direction is defined as width B. This width B corresponds to the distance from the wall surface 12b of the stepped portion 12S to the side surface 12a of the teeth 12.

[0060] In the example shown in Figure 6, the height A and width B of the stepped portion 12S of the teeth 12 are in the relationship A ≥ B. One example is A = B. In this case, the third surface 203 extends in an arc shape.

[0061] However, the shape of the teeth 12 is not limited to the shape shown in Figure 6. For example, as shown in Figure 7, the height A and width B of the stepped portion 12S of the teeth 12 may be in the relationship A > B. In this case, the third surface 203 extends in the axial direction, forming a long elliptical arc.

[0062] Figure 8 is a magnified view of the area around the stepped portion 12S of the tooth 12. The first surface 201 of the insulating portion 20 covers the end face 12e of the tooth 12 and further extends over the stepped portion 12S. The second surface 202 of the insulating portion 20 covers the side surface 12a of the tooth 12 and further extends over the stepped portion 12S.

[0063] Let point P be the boundary between the first surface 201 and the third surface 203 on a plane perpendicular to the extension direction of tooth 12. Also, let point Q be the boundary between the second surface 202 and the third surface 203.

[0064] Let distance D1 be the axial distance between point P and point Q. Let distance D2 be the distance between point P and point Q in the direction perpendicular to the axial direction. That is, if U is the intersection point of a first line L1 passing through point P and parallel to the axial direction, and a second line L2 passing through point Q and perpendicular to the axial direction, 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.

[0065] The height A and width B of the stepped portion 12S, and the distances D1 and D2 satisfy D1 ≤ A and D2 ≤ B. That is, point P does not face the end face 12e of the tooth 12, and point Q does not face the side surface 12a of the tooth 12. Therefore, there are no areas in the insulating portion 20 where the thickness is locally thinned.

[0066] <effect> The operation of Embodiment 1 will be explained in comparison with the comparative examples. Figure 9(A) is a cross-sectional view showing the teeth 121 and insulating portion 20C of Comparative Example 1. Figure 9(B) is a cross-sectional view showing the teeth 122 and insulating portion 20D of Comparative Example 2.

[0067] The tooth 121 of Comparative Example 1 shown in Figure 9(A) does not have a stepped portion at its axial end. That is, a 90-degree corner is formed between the end face 12e and the side surface 12a. The insulating portion 20C has a first surface 201 that covers the end face 12e of the tooth 121, a second surface 202 that faces the slot 14, and a third surface 203 between these surfaces 201 and 202. The third surface 203 faces the corner.

[0068] In order to wind the winding 30 around the insulating section 20C without causing 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 thickness t1 from the end face 12e of the teeth 121 to the first surface 201 of the insulating section 20C. Increasing the thickness t1 increases the circumference of the winding 30, and an increase in the circumference of the winding 30 increases copper loss.

[0069] The tooth 122 of Comparative Example 2 shown in Figure 9(B) has a stepped portion 12S between the end face 12e and the side surface 12a. The insulating portion 20D has a first surface 201 that covers the end face 12e of the tooth 122, a second surface 202 that faces the slot 14, and a third surface 203 between these surfaces 201 and 202. The third surface 203 faces the stepped portion 12S.

[0070] Because the teeth 122 have a stepped portion 12S, the thickness t1 from the end face 12e of the teeth 122 to the first face 201 of the insulating portion 20D can be reduced while increasing the radius of curvature of the third surface 203 of the insulating portion 20D.

[0071] Figure 9(C) is an enlarged view of the area around the stepped portion 12S of the tooth 122 in Comparative Example 2. In Comparative Example 2, point P, which is the boundary between the first surface 201 and the third surface 203 on a plane perpendicular to the extending direction of the tooth 122, is located opposite the end face 12e of the tooth 122. Also, point Q, which is the boundary between the second surface 202 and the third surface 203, is located opposite the side surface 12a of the tooth 122.

[0072] In other words, the axial distance D1 between point P and point Q, the distance D2 between point P and point Q in the direction perpendicular to the axial direction, the axial height A of the stepped portion 12S, and the width B of the stepped portion 12S in the direction perpendicular to the axial direction satisfy D1 > A and D2 > B.

[0073] In this case, a thin portion is created between the third surface 203 and the end face 12e of the tooth 12, as indicated by the symbol M. Similarly, a thin portion is created between the third surface 203 and the side surface 12a of the tooth 12, as indicated by the symbol N.

[0074] When thin sections like this occur, the insulating portion 20D becomes more susceptible to damage. To prevent damage to the insulating portion 20D, the thickness t1 from the end face 12e to the first face 201 needs to be increased. As a result, the thickness t1 increases, the circumference of the winding 30 increases, and it becomes more difficult to reduce copper loss.

[0075] In contrast, in Embodiment 1, as shown in Figure 8, the axial distance D1 between point P and point Q, the distance D2 between point P and point Q in a direction perpendicular to the axial direction, the height A of the stepped portion 12S, and the width B of the stepped portion 12S satisfy D1≦A and D2≦B. That is, point P does not face the end face 12e of the tooth 12, and point Q does not face the side surface 12a of the tooth 12.

[0076] Therefore, even if the radius of curvature of the third surface 203 of the insulating portion 20 is increased, no localized thinning of the thickness occurs. Consequently, even if the thickness t1 from the end face 12e of the teeth 12 to the first surface 201 of the insulating portion 20 is reduced, damage to the insulating portion 20 can be prevented. This allows for increased curvature of the third surface 203 to suppress winding bulging of the winding 30, and for a reduced thickness t1 to shorten the circumference of the winding 30. As a result, copper loss can be effectively reduced.

[0077] Next, the relationship between the height A and width B of the stepped section 12S will be explained. Figure 10 is a graph showing the relationship between the dimensional ratio A / B, which is the ratio of height A to width B, and the torque constant of the electric motor 100. The torque constant is the torque generated per unit current.

[0078] The torque constant of the electric motor 100 is a value obtained by performing an analysis while changing the height A and width B of the stepped portion 12S so that the ratio of the cross-sectional area (A×B) of the stepped portion 12S to the cross-sectional area (L1×W1) of the teeth 12 without the stepped portion 12S ((A×B) / (L1×W1)) remains constant.

[0079] As shown in Figure 10, the torque constant increases as the A / B value increases. The reason is as follows:

[0080] A core portion is formed at the axial end of the tooth 12, sandwiched between the end face 12e and the wall surfaces 12b on both sides. The wider the width B of the stepped portion 12S, the narrower the width of the core portion becomes, making magnetic saturation more likely to occur, and therefore making it more difficult for the magnetic flux of the rotor 5 to flow into the tooth 12. The narrower the width B of the stepped portion 12S, the wider the width of the core portion becomes, making magnetic saturation less likely to occur, and therefore making it easier for the magnetic flux of the rotor 5 to flow into the tooth 12.

[0081] Assuming a constant cross-sectional area of ​​the stepped portion 12S, the width B decreases as the height A of the stepped portion 12S increases. As described above, the smaller the width B, the less likely magnetic saturation is to occur, making it easier for the magnetic flux from the rotor 5 to flow into the teeth 12, resulting in a larger generated torque. Therefore, the larger the value of A / B, the larger the torque constant.

[0082] As the value of A / B increases, the torque constant increases, so for example, it can be seen that the case where A / B > 1 is preferable to the case where A / B ≤ 1. In other words, it can be seen that the configuration in which the height A and width B of the stepped portion 12S satisfy A > B, as shown in Figure 7, is preferable to the configuration in which the height A and width B of the stepped portion 12S satisfy A ≤ B, as shown in Figure 6.

[0083] Next, we will explain the relationship between the axial height A of the stepped portion 12S and the axial length L1 of the teeth 12. Figure 11 is a graph showing the relationship between the ratio A / L1 of the axial height A of the stepped portion 12S to the axial length L1 of the teeth 12 and the rate of change of iron loss and copper loss.

[0084] The values ​​for iron loss and copper loss were obtained by performing an analysis while changing the height A and width B so that the ratio of the cross-sectional area of ​​the stepped portion 12S (A×B) to the cross-sectional area of ​​the tooth 12 without the stepped portion 12S (L1×W1) ((A×B) / (L1×W1)) remains constant. Furthermore, the values ​​for iron loss and copper loss are expressed as relative values ​​to the values ​​for iron loss and copper loss when the tooth 12 does not have the stepped portion 12S.

[0085] As shown in Figure 11, as the value of A / L1 increases, copper loss decreases and iron loss increases. The reason why copper loss decreases as the value of A / L1 increases is that, assuming the cross-sectional area (A × B) of the stepped portion 12S is constant, as the height A of the stepped portion 12S increases (i.e., as the width B decreases), magnetic flux from the rotor 5 flows in more easily due to the suppression of magnetic saturation, and the current value can be reduced accordingly.

[0086] Furthermore, the reason why iron loss increases as the value of A / L1 increases is that as the ratio of the height A of the stepped portion 12S to the length L1 of the teeth 12 increases, the proportion of the narrow portion of the teeth 12 increases, and the overall magnetic resistance of the teeth 12 increases.

[0087] From Figure 11, the rate of increase in iron loss and the rate of decrease in copper loss are the same when A / L1 = 0.157, compared to the case where teeth 12 do not have the stepped portion 12S. That is, when A / L1 = 0.157, copper loss increases by 0.7% and iron loss also increases by 0.7% compared to the case where teeth 12 do not have the stepped portion 12S.

[0088] When A / L1 < 0.157, the increase in copper loss is greater than the increase in iron loss compared to the case where teeth 12 do not have the stepped portion 12S. When A / L1 > 0.157, the increase in iron loss is greater than the increase in copper loss compared to the case where teeth 12 do not have the stepped portion 12S.

[0089] In this embodiment, copper loss can be reduced by preventing the winding bulge of the winding 30, so a range of A / L1 ≤ 0.157 is desirable, where the increase in iron loss is equal to or less than the increase in copper loss.

[0090] The electric motor 100 used in the compressor is designed according to the compressor's requirements, but it is desirable that the shape of the stator core 10 be common, and that various requirements be accommodated by adjusting the width of the core back 11 or teeth 12, or the number of turns of the winding 30. In this embodiment, copper loss and iron loss can be reduced by the shape of the stator core 10, so that a highly efficient electric motor 100 that can accommodate various requirements can be realized.

[0091] Next, the relationship between the stepped portions 11S, 12S, and 13S of the core back 11, tooth 12, and tooth tip 13 will be explained. As shown in Figure 4, the core back 11 has a stepped portion 11S, the tooth 12 has a stepped portion 12S, and the tooth tip 13 has a stepped portion 13S.

[0092] The stepped portion 11S of the core back 11 has a radial width E1 centered on the axis Ax (Figure 1). The width E1 corresponds to the amount of radial displacement of the wall surface 11b of the stepped portion 11S from the inner circumferential surface 11a of the core back 11.

[0093] The stepped portion 13S of the tooth tip 13 has a radial width E2 centered on the axis Ax. The width E2 corresponds to the radial displacement of the wall surface 13b of the stepped portion 13S from the outer surface 13a of the tooth tip 13. The stepped portion 12S of the tooth 12 has a width B as described above.

[0094] Of the insulating portion 20, the winding 30 is wound around the body portion 22 that covers the teeth 12. On the other hand, the winding 30 is not wound around the wall portion 21 attached to the core back 11 and the flange portion 23 attached to the tooth tip portion 13. Therefore, the width B of the stepped portion 12S of the teeth 12 is related to the winding bulge state of the winding 30, but the widths E1 and E2 of the stepped portions 11S and 13S of the core back 11 and tooth tip portion 13 are not related to the winding bulge state of the winding 30.

[0095] Therefore, it is desirable that the width B of the stepped portion 12S of the tooth 12 is wider than the width E1 of the stepped portion 11S of the core back 11, and also wider than the width E2 of the stepped portion 13S of the tooth tip 13. In other words, it is desirable that B > E1 and B > E2 hold true. This makes it possible to reduce magnetic resistance at the core back 11 and the tooth tip 13 while suppressing the winding bulge of the winding 30 wound around the tooth 12.

[0096] Although this example describes a stator core 10 composed of multiple segmented cores 10A, the stator core 10 is not limited to such a configuration. In other words, the stator core 10 may be a single integrated core formed by stacking annularly punched electromagnetic steel sheets in the axial direction.

[0097] Furthermore, although an example in which stepped portions 12S are formed on both sides of the tooth 12 in the circumferential direction has been described here, it is sufficient for the stepped portions 12S to be formed on at least one side of the tooth 12 in the circumferential direction. Also, although stepped portions 11S and 13S are provided on the core back 11 and tooth tip portion 13 here, these stepped portions 11S and 13S do not necessarily have to be provided.

[0098] <Effects of the Embodiment> As described above, the stator 1 of Embodiment 1 has a core back 11 and teeth 12, and windings 30 are wound around the teeth 12 via an insulating portion 20. The teeth 12 have an axially oriented end face 12e, a side surface 12a facing the slot 14, and a stepped portion 12S formed between the end face 12e and the side surface 12a. The insulating portion 20 has a first surface 201 covering the end face 12e of the teeth 12, a second surface 202 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. In a cross-section perpendicular to the extending direction of the teeth 12, point P is the boundary between the first surface 201 and the third surface 203 of the insulating portion 20, point Q is the boundary between the second surface 202 and the third surface 203, and U is the intersection of a first straight line L1 passing through point P and parallel to the axial direction, and a second straight line L2 passing through point Q and perpendicular to the axial direction. The axial height A of the stepped portion 12S, the width B of the stepped portion 12S in the direction perpendicular to the axial direction, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U satisfy D1≦A and D2≦B.

[0099] Because of this configuration, 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 portion 20 is increased, no locally thinned areas occur, and stress concentration can be suppressed. This makes it possible to reduce the thickness of the insulating portion 20 while preventing the winding 30 from bulging. In other words, the circumference of the winding 30 can be shortened, and copper loss can be reduced.

[0100] Furthermore, since the height A and width B of the stepped portion 12S satisfy A > B, magnetic saturation is less likely to occur within the teeth 12, and the magnetic flux from the rotor 5 flows more easily into the teeth 12, thus allowing the torque constant to be increased.

[0101] In addition, since the axial height A of the stepped portion 12S and the axial length L1 of the stator core 10 satisfy A / L1 ≤ 0.157, the increase in iron loss and copper loss in the teeth 12 can be suppressed.

[0102] Furthermore, the insulating portion 20 is integrally formed with a portion that covers the end face 12e of the teeth 12, a portion that covers the side surface 12a, and a portion that covers the stepped portion 12S. Therefore, the insulating portion 20 can be formed in a simple process, for example, by integral molding with resin.

[0103] Furthermore, since the winding 30 is made of aluminum wire, the flexibility of the aluminum wire can be used to tightly wind the winding 30 onto the teeth 12. Although aluminum wire has higher electrical resistance than copper wire, in this embodiment the circumference of the winding 30 can be shortened, so even when using aluminum wire, the increase in copper loss can be suppressed.

[0104] Embodiment 2. Next, Embodiment 2 will be described. In Embodiment 1, stepped portions 12S were formed at both ends of the stator 1 in the axial direction. In contrast, in Embodiment 2, the stepped portion 12S is formed only at one end of the stator 1 in the axial direction.

[0105] Figure 12 shows the relationship between the stator core 10 and the rotor core 50 of the electric motor in Embodiment 2. In Figure 12, the direction toward the compression mechanism 9 (Figure 18) of the compressor 8 is shown as the -Z direction, and the opposite direction is shown as the +Z direction. In Figure 12, the +Z direction is upward and the -Z direction is downward, but this is not the only way to represent the direction.

[0106] The end face 50e of the rotor core 50 in the +Z direction is located in the +Z direction more than the end face 10e of the stator core 10 in the +Z direction. The end face 50e of the rotor core 50 in the -Z direction is located in the +Z direction more than the end face 10e of the stator core 10 in the -Z direction.

[0107] In other words, the rotor core 50 protrudes more in the +Z direction than the stator core 10. That is, the axial center position of the rotor core 50 is displaced in the +Z direction compared to the axial center position of the stator core 10.

[0108] Therefore, a magnetic attraction force acts between the stator core 10 and the rotor core 50 in a direction that brings their central positions closer together in the axial direction. This magnetic attraction force biases the rotor 5 in the -Z direction, i.e., towards the compression mechanism 9, thereby suppressing vibration of the rotor 5.

[0109] In Embodiment 2, the stepped portion 12S is not formed at the +Z end of the tooth 120. On the other hand, the stepped portion 12S is formed at the -Z end of the tooth 120. The shape and dimensions of the stepped portion 12S are as described in Embodiment 1.

[0110] As described in Embodiment 1, the axial length of the stepped portion 12S of the teeth 120 is the height A. L1 is the axial length of the region of the core area R1 with height A in the axial direction from the end face 10e in the -Z direction of the stator core 10 that faces the rotor core 50.

[0111] Similarly, L2 is defined as the axial length of the core region R2, which has an axial height A from the end face 10e in the +Z direction of the stator core 10, that faces the rotor core 50. Core region R1 is also referred to as the first region, and core region R2 is also referred to as the second region.

[0112] In the core regions R1 and R2 of the stator core 10, the lengths L1 and L2 of the opposing regions with the rotor core 50 satisfy L1 < L2. In other words, when core regions R1 and R2 of the same height A are defined at both axial ends of the stator core 10, the step portion 12S of the teeth 120 is formed on the side where the ratio of the opposing region with the rotor core 50 in the core regions R1 and R2 is smaller.

[0113] In the core region R2 of the stator core 10, since the ratio of the opposing region with the rotor core 50 is large, more magnetic flux flows in from the rotor 5. Therefore, if the step portion 12S is provided in the core region R2 of the teeth 120, magnetic saturation is likely to occur, and iron loss may increase.

[0114] Therefore, in the second embodiment, the step portion 12S is provided only in the core region R1 where the inflowing magnetic flux from the rotor core 50 is small. That is, the step portion 12S is provided only at the -Z direction end of the stator core 10. Also, although not shown, the step portion 11S of the core back 11 and the step portion 13S of the tooth tip portion 13 are also provided only at the -Z direction end of the stator core 10.

[0115] FIG. 13 is a cross-sectional view in a plane orthogonal to the extending direction of the teeth 120, showing the teeth 120 and the insulating portion 20A of the second embodiment. As shown in FIG. 13, a step portion 12S is provided at the -Z direction end of the teeth 120. The shape and dimensions of the step portion 12S are as described in the first embodiment.

[0116] On the other hand, no step portion 12S is provided at the +Z direction end of the teeth 120. Therefore, a 90-degree corner is formed between the +Z direction end face 12e and the side face 12a of the teeth 120.

[0117] The insulating portion 20A has a first surface 201 that covers the end face 12e of the teeth 120, a second surface 202 that faces the slot 14, and a third surface 203 that extends from the first surface 201 to the second surface 202. The thickness t1 from the end face 12e of the teeth 120 to the first surface 201 of the insulating portion 20A is longer at the +Z direction end than at the -Z direction end.

[0118] Except for the points mentioned above, the motor of Embodiment 2 is configured in the same way as the motor 100 of Embodiment 1.

[0119] As described above, in Embodiment 2, a stepped portion 12S is provided on the teeth 120 at the end of the stator core 10 that has a smaller area facing the rotor core 50 when the axial length is the same. Therefore, while suppressing magnetic saturation in the teeth 120, the circumference of the winding 30 can be shortened and copper loss can be reduced.

[0120] Variant expression. Figure 14 shows the relationship between the stator core 10 and the rotor core 50 in a modified example of Embodiment 2. In this modified example, the rotor core 50 protrudes from the stator core 10 on both axial sides, i.e., in the +Z and -Z directions. However, the amount of protrusion Z2 of the rotor core 50 in the +Z direction is greater than the amount of protrusion Z1 in the -Z direction.

[0121] This configuration, in which the rotor core 50 protrudes from the stator core 10 on both axial sides, shortens the axial length of the stator core 10 and reduces the material cost of the stator core 10.

[0122] On the other hand, magnetic flux from the protruding portion of the rotor core 50 also flows into the stator core 10. 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.

[0123] Therefore, in the modified example, the stepped portion 12S is provided on the teeth 120 only at the -Z end of the stator core 10 where the incoming magnetic flux from the rotor core 50 is small. Although not shown in the illustration, the stepped portion 11S of the core back 11 and the stepped portion 13S of the tooth tip 13 are also provided only at the -Z end of the stator core 10.

[0124] In this modified example, as in Embodiment 2, the circumference of the winding 30 can be shortened while suppressing magnetic saturation in the teeth 120, thereby reducing copper loss.

[0125] Embodiment 3. Next, Embodiment 3 will be described. Figure 15 is a perspective view showing the teeth 12 and insulating portion 20B of Embodiment 3. The insulating portion 20B of Embodiment 3 has an insulator 25 that covers the end face 12e of the teeth 12 and an insulating film 26 that covers the side surface 12a of the teeth 12. Specifically, the insulator 25 is provided on both sides of the teeth 12 in the axial direction, and the insulating film 26 is provided on both sides of the teeth 12 in the circumferential direction.

[0126] Each insulator 25 is made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP). Each insulating film 26 is a film made of a resin such as polyethylene terephthalate (PET). The thickness of the insulating film 26 is, for example, 0.35 mm.

[0127] Each insulator 25 has a wall portion 27 attached to the core back 11, a body portion 28 attached to the teeth 12, and a flange portion 29 attached to the tooth tip portion 13.

[0128] The wall portion 27 engages with the stepped portion 11S of the core back 11 and further protrudes in the axial direction. The portion of the wall portion 27 that engages with the stepped portion 11S of the core back 11 is referred to as the engaging portion 27a.

[0129] The body portion 28 covers the end face 12e of the teeth 12 and engages with the stepped portion 12S of the teeth 12. The portion of the body portion 28 that engages with the stepped portion 11S of the core back 11 is referred to as the engaging portion 28a. The body portion 28 has a first surface 201 facing axially, a second surface 202 facing the slot 14, and a third surface 203 extending from the first surface 201 to the second surface 202.

[0130] The flange portion 29 covers the end face 13e of the tooth tip portion 13 and engages with the stepped portion 13S of the tooth tip portion 13. The portion of the flange portion 29 that engages with the stepped portion 13S of the tooth tip portion 13 is referred to as the engaging portion 29a.

[0131] The insulator 25 also has an extended portion 24 that extends radially outward from the wall portion 21. The extended portion 24 has a projection 24a that fits into a fitting hole 16 formed in the core back 11. The insulator 25 is fixed to the divided core 10A by the fitting of the projection 24a and the fitting hole 16. Note that the projection 24a is not necessarily required to be provided on the insulator 25.

[0132] The insulating film 26 is provided so as to cover the inner circumferential surface 11a of the core back 11, the side surface 12a of the teeth 12, and the outer surface 13a of the tooth tip portion 13. In other words, the insulating film 26 is provided so as to cover the inner surface of the slot 14.

[0133] The winding 30 is wrapped around the body 28 and insulating film 26 of the insulator 25. The wall 27 and flange 29 of the insulator 25 also guide the winding 30 from both radial sides.

[0134] Figure 16 is a cross-sectional view of the teeth 12 and insulating portion 20B of Embodiment 3 in a plane perpendicular to the direction of extension of the teeth 12. Since the insulating portion 20B of Embodiment 3 is formed of an insulator 25 and an insulating film 26 made of different materials, it is necessary to ensure an insulating distance from the stator core 10 to the winding 30. The insulating distance is the shortest distance between conductors measured along the surface of the insulator, and is also called the creepage distance.

[0135] The insulating film 26 further protrudes axially from the side surface 12a of the tooth 12. In other words, the insulating film 26 not only covers the side surface 12a of the tooth 12 but also extends to partially cover the second surface 202 of the insulator 25.

[0136] Let D be the amount of axial protrusion of the stepped portion 12S of the insulating film 26 from the bottom surface 12c. The amount of protrusion D of the insulating film 26 is set to be greater than or equal to the creepage distance from the stator core 10 to the winding 30. The insulation distance is, for example, 2.5 mm.

[0137] Figure 17 is a cross-sectional view of the teeth 121 and insulating portion 20E of Comparative Example 3. The teeth 121 of Comparative Example 3 does not have a stepped portion. The insulating portion 20E has an insulator 25 that covers the end face 12e of the teeth 121 and an insulating film 26 that covers the side surface 12a of the teeth 121.

[0138] The insulating film 26 is provided so as to protrude axially from the end face 12e of the teeth 121. Let D be the amount of axial protrusion of the insulating film 26 from the end face 12e of the teeth 121. The amount of protrusion D is greater than or equal to the insulation distance described above.

[0139] If the insulating film 26 protrudes axially beyond the insulating portion 20E, the insulating film 26 may bend inward into the slot 14 when winding the winding 30. Therefore, the thickness t1 from the end face 12e of the teeth 121 to the first surface 201 of the insulating portion 20E must be greater than or equal to the protrusion amount D, which increases the thickness t1.

[0140] In contrast, in Embodiment 3, since the teeth 12 have a stepped portion 12S, even if the insulating film 26 protrudes by a protrusion amount D from the bottom surface 12c of the stepped portion 12S, the thickness t1 from the end face 12e of the teeth 12 to the first surface 201 can be reduced. This makes it possible to shorten the circumference of the winding 30.

[0141] As described above, in Embodiment 3, since the teeth 12 have a stepped portion 12S and the insulating portion 20 has an insulating film 26 that covers the side surface 12a of the teeth 12, the circumference of the winding 30 can be shortened while ensuring the insulation distance, thereby reducing copper loss.

[0142] <Compressor> Next, a compressor 8 using an electric motor 100 will be described. Figure 18 is a cross-sectional view showing the configuration of the compressor 8. The compressor 8 is a rotary compressor and comprises a shell 80, a compression mechanism 9 disposed within 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 in a power-transmitting manner. The shaft 90 is the shaft 65 shown in Figure 1, etc., and fits into the central hole 53 of the rotor 5 of the electric motor 100.

[0143] The shell 80 is a sealed container formed, for example, from a steel plate, and encloses 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, which serves as a terminal for supplying power to the electric motor 100 from outside the compressor 8, and a discharge pipe 85 for discharging the refrigerant compressed inside the compressor 8 to the outside. The lower shell 80b houses the electric motor 100 and the compression mechanism 9.

[0144] The compression mechanism 9 has annular first cylinder 91 and second cylinder 92 along the shaft 90. The first cylinder 91 and second cylinder 92 are fixed to the inner circumference of the shell 80 (lower shell 80b). An annular first piston 93 is positioned on the inner circumference side of the first cylinder 91, and an annular second piston 94 is positioned on the inner circumference side of the second cylinder 92. The first piston 93 and second piston 94 are rotary pistons that rotate together with the shaft 90.

[0145] A partition plate 97 is provided between the first cylinder 91 and the second cylinder 92. The partition plate 97 is a disc-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 chamber 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.

[0146] An upper frame 95 is positioned above the first cylinder 91 so as to close the upper part of the cylinder chamber of the first cylinder 91. A lower frame 96 is positioned below the second cylinder 92 so as to close the lower part of the cylinder chamber of the second cylinder 92. The upper frame 95 and the lower frame 96 rotatably support the shaft 90.

[0147] The bottom of the lower shell 80b of the shell 80 stores refrigerant oil (not shown) to lubricate each sliding part of the compression mechanism 9. The refrigerant oil rises through holes 90a formed axially inside the shaft 90 and is supplied to each sliding part through oil supply holes 90b formed at multiple locations on the shaft 90.

[0148] The stator 1 of the electric motor 100 is attached to the inside of the shell 80 by shrink-fitting. Power is supplied to the windings 30 of the stator 1 from glass terminals 81 attached to the upper shell 80a. The shaft 90 is fixed to the central hole 53 (Figure 1) of the rotor 5.

[0149] An accumulator 87 for storing refrigerant gas is attached to the shell 80. The accumulator 87 is held, for example, by a retaining part 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 these suction pipes 88, 89.

[0150] As refrigerants, for example, R410A, R407C, or R22 may be used, but from the perspective of preventing global warming, it is desirable to use refrigerants with a low GWP (Global Warming Potential). Examples of low GWP refrigerants that can be used include the following:

[0151] (1) First, halogenated hydrocarbons having a carbon double bond in their composition, such as HFO(Hydro-Fluoro-Orefin)-1234yf(CF3CF=CH2), can be used. The GWP of HFO-1234yf is 4. (2) Alternatively, hydrocarbons having a carbon double bond in the composition, such as R1270 (propylene), may be used. The GWP of R1270 is 3, which is lower than that of HFO-1234yf, but its flammability is higher than that of HFO-1234yf. (3) Alternatively, a mixture containing at least one halogenated hydrocarbon having a carbon double bond in its composition or a hydrocarbon having a carbon double bond in its composition, for example, a mixture of HFO-1234yf and R32 may be used. As mentioned above, HFO-1234yf is a low-pressure refrigerant and tends to cause a large pressure drop, which can 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 with R32 or R41, which are higher-pressure refrigerants than HFO-1234yf.

[0152] The basic operation of the compressor 8 is as follows: The refrigerant gas supplied from the accumulator 87 is supplied to the cylinder chambers of the first cylinder 91 and the second cylinder 92 through the suction pipes 88 and 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, which are fitted onto the shaft 90, rotate eccentrically within each cylinder chamber, compressing the refrigerant within each cylinder chamber. The compressed refrigerant rises through the holes 57 and 58 (Figure 1) of the rotor 5 inside the shell 80 and is discharged to the outside from the discharge pipe 85.

[0153] Furthermore, the compressor using the electric motor 100 is not limited to a rotary compressor; for example, a scroll compressor or the like may also be used.

[0154] Since the electric motor 100 in each embodiment has high motor efficiency due to the reduction of copper loss in the winding 30, the operating efficiency of the compressor 8 can be improved.

[0155] <Refrigeration cycle equipment> Next, a refrigeration cycle device 400 having a compressor 8 shown in Figure 18 will be described. Figure 19 is a diagram showing the refrigeration cycle device 400. The refrigeration cycle device 400 is, for example, an air conditioning system, but is not limited to this, and may be, for example, a refrigerator.

[0156] The refrigeration cycle device 400 shown in Figure 19 comprises a compressor 401, a condenser 402 for condensing the refrigerant, a pressure reducing device 403 for reducing the pressure of the refrigerant, and an evaporator 404 for evaporating the refrigerant. The compressor 401, condenser 402, and pressure reducing device 403 are installed in the outdoor unit 410, and the evaporator 404 is installed in the indoor unit 420.

[0157] The compressor 401, condenser 402, pressure reducing device 403, and evaporator 404 are connected by refrigerant piping 407 to form a refrigerant circuit. The compressor 401 is composed of the compressor 8 shown in Figure 18. The refrigeration cycle device 400 also includes an outdoor fan 405 facing the condenser 402 and an indoor fan 406 facing the evaporator 404.

[0158] The operation of the refrigeration cycle unit 400 is as follows: The compressor 401 compresses the inhaled refrigerant and sends it out as a high-temperature, high-pressure refrigerant gas. The condenser 402 exchanges heat between the refrigerant sent out from the compressor 401 and the outdoor air sent by the outdoor fan 405, condensing the refrigerant and sending it out as liquid refrigerant. The depressurizing device 403 expands the liquid refrigerant sent out from the condenser 402 and sends it out as a low-temperature, low-pressure liquid refrigerant.

[0159] The evaporator 404 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 403 and the indoor air, evaporating the refrigerant and sending it out as refrigerant gas. The air from which heat has been removed in the evaporator 404 is supplied to the room by the indoor fan 406.

[0160] Since the electric motor 100 described in each embodiment can be applied to the compressor 401 of the refrigeration cycle device 400, the operating efficiency of the refrigeration cycle device 400 can be improved.

[0161] Although preferred embodiments have been described in detail above, this disclosure is not limited to the embodiments described above, and various improvements or modifications can be made. [Explanation of Symbols]

[0162] 1 Stator, 20, 20A, 20B Insulation section, 5 Rotor, 8 Compressor, 9 Compression mechanism, 10 Stator core, 10A Split core, 11 Core back, 11S Step section, 12, 120 Teeth, 12S Step section, 12a Side, 12e End face, 13 Tooth tip, 13S Step section, 14 Slot, 15 Split surface, 21 Wall section, 22 Body section, 23 Flange section, 25 Insulator, 26 Insulating film, 30 Winding, 50 Rotor core, 51 Magnet insertion hole, 60 Permanent magnet, 65 Shaft, 80 Shell, 100 Motor, 201 First surface, 202 Second surface, 203 Third surface, 400 Refrigeration cycle unit, 401 Compressor, 402 Condenser, 403 Pressure reducer, 404 Evaporator.

Claims

1. A stator used in conjunction with a rotor, 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, and facing the rotor core of the rotor, An insulating portion provided on the teeth, The winding is wrapped around the teeth via the insulating portion. It has, The stator core has a first region of height A at one end in the axial direction and a second region of height A at the other end in the axial direction. The length of the portion of the first region facing the rotor core is shorter than the length of the portion of the second region facing the rotor core. In the first region of the stator core, of the first and second regions, the teeth have an end face facing the axial direction, a side surface facing the slot, and a stepped portion formed between the end face and the side surface. 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 or inclined surface that extends from the first surface to the second surface. In a cross-section perpendicular to the extending direction of the teeth, let P be the boundary between the first surface and the third surface, let Q be the boundary between the second surface and the third surface, and let U be the intersection of a first straight line passing through point P and parallel to the axial direction and a second straight line passing through point Q and perpendicular to the axial direction. The axial height A of the stepped portion, the width B of the stepped portion in the direction perpendicular to the axial direction, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U are, Satisfying D1 ≤ A and D2 ≤ B stata.

2. A stator used in conjunction with a rotor, 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, and facing the rotor core of the rotor, An insulating portion provided on the teeth, The winding is wrapped around the teeth via the insulating portion. It has, The rotor core protrudes by a distance Z1 from one end of the stator core in the axial direction, and by a distance Z2 from the other end of the stator core in the axial direction. The distance Z1 is shorter than the distance Z2. Of the one end and the other end of the stator core, on the side of the one end only, the teeth have an end face facing the axial direction, a side surface facing the slot, and a stepped portion formed between the end face and the side surface. 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 or inclined surface that extends from the first surface to the second surface. In a cross-section perpendicular to the extending direction of the teeth, let P be the boundary between the first surface and the third surface, let Q be the boundary between the second surface and the third surface, and let U be the intersection of a first straight line passing through point P and parallel to the axial direction and a second straight line passing through point Q and perpendicular to the axial direction. The axial height A of the stepped portion, the width B of the stepped portion in the direction perpendicular to the axial direction, the distance D1 from point P to intersection U, and the distance D2 from point Q to intersection U are, Satisfying D1 ≤ A and D2 ≤ B stata.

3. The height A and width B of the stepped portion satisfy A > B. The stator according to claim 1 or 2.

4. With respect to the axial length L1 of the teeth, the height A of the stepped portion is A / L1≦0.157 Satisfy The stator according to claim 3.

5. The insulating portion has an insulating film that covers the side surface of the teeth. The stator according to claim 1 or 2.

6. The winding is made of aluminum wire. The stator according to claim 1 or 2.

7. A stator according to claim 1 or 2, The rotor and the stator are located inside the rotor. An electric motor equipped with [a specific feature].

8. The electric motor according to claim 7, A compression mechanism driven by the aforementioned electric motor and A compressor equipped with a compressor.

9. The compressor, condenser, pressure reducing device, and evaporator are provided as described in claim 8. Refrigeration cycle device.

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