Stator, electric motor, compressor, and refrigeration cycle device

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

Stator, electric motor, compressor and refrigeration cycle device

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

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

[0003] JP 2016-82683 A (see abstract)

[0004] However, providing steps on the teeth creates locally thin portions in the insulating portion covering the teeth, making the insulating portion more susceptible to damage.If the insulating portion is made thicker to prevent damage, the perimeter of the winding will become longer.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to shorten the circumferential length of the winding.

[0006] A stator according to the present disclosure includes 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, insulating portions provided on the teeth, and windings wound around the teeth via the insulating portions. The teeth have end faces facing the axial direction of the stator core, side faces facing the slots, and stepped portions formed between the end faces and the side faces. The insulating portions have first faces covering the end faces of the teeth, second faces facing the slots, and a third face that is a curved or inclined surface extending from the first face to the second face. In a cross section perpendicular to the extension direction of the teeth, the boundary between the first face and the third face is defined as point P, the boundary between the second face and the third face is defined as point Q, and the intersection point U is defined as a first line passing through point P and parallel to the axial direction and a second line passing through point Q and perpendicular to the axial direction. The axial height A of the step portion, the width B of the step portion 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.

[0007] In the present disclosure, the height A and width B of the step portion, the distance D1 from point P to intersection point U, and the distance D2 from point Q to intersection point U satisfy D1≦A and D2≦B, so point P does not face the end face of the tooth, and point Q does not face the side face of the tooth. This prevents stress concentration in the insulating portion. As a result, the thickness of the insulating portion can be reduced, allowing the circumferential length of the winding to be shortened.

[0008] 1 is a cross-sectional view showing an electric motor according to a first embodiment. FIG. 2 is a diagram showing the axial positional relationship between a stator core and a rotor core according to the first embodiment. FIG. 3 is a plan view showing a stator core according to the first embodiment. FIG. 4 is a perspective view showing a divided core according to the first embodiment. FIG. 5 is a perspective view showing a divided core and an insulating portion according to the first embodiment. FIG. 6 is a cross-sectional view showing teeth and insulating portions according to the first embodiment. FIG. 7 is a cross-sectional view showing another example of teeth and insulating portions according to the first embodiment. FIG. 8 is an enlarged view of a step portion of a tooth according to the first embodiment. FIG. 9 is a cross-sectional view showing teeth and insulating portions according to a first comparative example, FIG. 10 is a cross-sectional view showing teeth and insulating portions according to a second comparative example, and FIG. 11 is an enlarged view of a step portion of a tooth according to the first embodiment. FIG. 11 is a graph showing the relationship between a dimensional ratio A / B of a step portion according to the first embodiment and a torque constant. FIG. 12 is a graph showing the relationship between a ratio A / L1 of a height A of a step portion to a length L1 of a tooth according to the first embodiment and a rate of change in loss. FIG. 13 is a diagram showing the axial positional relationship between a stator core and a rotor core according to a second embodiment. FIG. 14 is a cross-sectional view showing teeth and insulating portions according to the second embodiment. Fig. 18 is a perspective view showing a split core and an insulating part of embodiment 3. Fig. 19 is a cross-sectional view showing a tooth and an insulating part of embodiment 3. Fig. 20 is a cross-sectional view showing a tooth and an insulating part of comparative example 3. Fig. 21 is a longitudinal cross-sectional view showing a compressor to which the electric motor of each embodiment can be applied. Fig. 22 is a view showing a refrigeration cycle device to which the compressor of Fig. 18 can be applied.

[0009] First Embodiment <Configuration of Electric Motor> First, a first embodiment will be described. Fig. 1 is a cross-sectional view showing an electric motor 100 according to the first embodiment. 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. 18).

[0010] The electric motor 100 has a rotor 5 having a shaft 65 as a rotating shaft, and a stator 1 provided to surround 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 a cylindrical shell 80 of a compressor 8 (FIG. 18) described below.

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

[0012] <Configuration of Rotor> 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 stacking a plurality of electromagnetic steel plates in the axial direction and fixing them by caulking or the like.

[0013] The thickness of the electromagnetic steel plate is 0.1 to 0.7 mm. A center hole 53 is formed in the radial center of rotor core 50. Shaft 65 is fixed in center hole 53 of rotor core 50 by shrink fitting, press fitting, adhesive, or the like. Rotor core 50 has a circumferential outer periphery centered on axis Ax.

[0014] A plurality of magnet insertion holes 51 into which permanent magnets 60 are inserted 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 here is six. 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.

[0015] 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 in a V-shape, for example.

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

[0017] 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.

[0018] In rotor core 50, flux barriers 52, which are holes, are formed at both circumferential ends of magnet insertion holes 51. A thin-walled portion is formed between each flux barrier 52 and the outer periphery of 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.

[0019] 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. Furthermore, the rotor core 50 does not necessarily have to have the slits 54.

[0020] In the rotor core 50, holes 57 and 58 are formed radially inward of the magnet insertion holes 51. The holes 57 and 58 are used as vents for passing a refrigerant or as holes for inserting jigs. The number of holes 57 and 58 is the same 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 and 58 are not limited to the example described here. Furthermore, the rotor core 50 does not necessarily have to have the holes 57 and 58.

[0021] Furthermore, crimped portions 56 are formed on the radial outside of each hole portion 58 to secure the electromagnetic steel sheets of the rotor core 50. However, the arrangement of the crimped portions 56 is not limited to the example described here. Furthermore, the electromagnetic steel sheets of the rotor core 50 may be secured by a method other than crimping.

[0022] <Configuration of Stator> The stator 1 has a stator core 10 that surrounds the rotor core 50 from the outside in the radial direction, 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 caulking or the like. The thickness of the electromagnetic steel plates 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 nine here. However, the number of teeth 12 is not limited to nine, as long as it is two or more. Slots 14 are formed between circumferentially adjacent teeth 12. The number of slots 14 is nine, the same as the number of teeth 12.

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

[0025] 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. Furthermore, aluminum wire is cheaper than copper wire, which is advantageous in reducing manufacturing costs.

[0026] Fig. 2 is a diagram showing the axial positional relationship between the stator core 10 and the rotor core 50. As shown in Fig. 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.

[0027] 2 , it is sufficient that the axial center position of the stator core 10 coincides with the axial center position of the rotor core 50. A case in which the axial center position of the stator core 10 differs from the axial center position of the rotor core 50 will be described in a second embodiment.

[0028] 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 is fitted into a shell 80 of the compressor 8 (FIG. 18).

[0029] 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 referred to as a tooth center line T1. Each tooth 12 has a pair of side surfaces 12a on both circumferential sides. The side surfaces 12a of the teeth 12 face the slots 14.

[0030] Each tooth 12 also has a tooth tip 13 that faces the rotor 5 (FIG. 1). The tooth tip 13 is wider in the circumferential direction than the other parts of the tooth 12 and protrudes in the circumferential direction beyond the side surface 12a of the tooth 12. An outer surface 13a is formed radially outward from the protruding part of the tooth tip 13. The outer surface 13a of the tooth tip 13 faces the slot 14.

[0031] Although the tooth tip portion 13 is a part of the tooth 12, the tooth tip portion 13 may be described separately from the other parts of the tooth 12 because the shape of the tooth tip portion 13 is different from the other parts of the tooth 12.

[0032] Steps 12S are formed at the axial ends of the teeth 12. The step 12S is formed on the side surface 12a side of the teeth 12, i.e., on the slot 14 side. Therefore, the circumferential width of the teeth 12 is narrower at the axial ends than at the axial center.

[0033] A step portion 11S is formed at the axial end portion of the core back 11. The step 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 portion than at the axial center portion.

[0034] A step 13S is formed at the axial end of the tooth tip 13. The step 13S is formed on the outer surface 13a side of the tooth tip 13, i.e., on the slot 14 side. Therefore, the radial width of the protruding portion of the tooth tip 13 is narrower at the axial end than at the axial center.

[0035] The core back 11 is also formed with a dividing surface 15 that divides the stator core 10. The dividing surface 15 is formed at a midpoint between two circumferentially adjacent teeth 12. The dividing surface 15 is formed from the inner peripheral surface 11a of the core back 11 to the outer peripheral surface.

[0036] Stator core 10 is divided by dividing surfaces 15 into nine divided cores 10A, each including one tooth 12. In other words, stator core 10 is formed by combining a plurality of divided cores 10A.

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

[0038] Fig. 4 is a perspective view showing the split core 10A. 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 end face 11e facing the axial direction. The teeth 12 have end faces 12e facing the axial direction. The tooth tips 13 have end faces 13e facing the axial direction.

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

[0040] 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.

[0041] 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.

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

[0043] The bottom surfaces 11c, 12c, and 13c of the stepped portions 11S, 12S, and 13S are located on the same plane, so that the axial heights of the stepped portions 11S, 12S, and 13S (height A, which will be described later) are the same.

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

[0045] 5 is a perspective view showing the split core 10A and the insulating portion 20. The insulating portion 20 is attached to the split core 10A 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).

[0046] The insulating portion 20 has a body portion 22 that covers the teeth 12, a wall portion 21 arranged radially outside the body portion 22, and a flange portion 23 arranged radially inside the body portion 22. The wall portion 21 and the flange portion 23 face each other in the radial direction with the body portion 22 sandwiched therebetween.

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

[0048] The body portion 22 is provided to cover the end faces 12e and side faces 12a (FIG. 4) of the teeth 12. The body portion 22 has an engaging portion 22a (FIG. 6) that engages with the step portion 12S (FIG. 4) of the teeth 12.

[0049] The flange portion 23 is provided so as 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 engaging portion 23a that engages with the step portion 13S of the tooth tip portion 13.

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

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

[0052] Here, the insulating part 20 is described as being integrally formed, but it may be formed of an insulator and an insulating film, as will be described in the third embodiment.

[0053] 6 is a cross-sectional view showing the teeth 12 and the insulating portions 20, taken along a plane perpendicular to the extending direction of the teeth 12. The extending 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 center line T1 (FIG. 3).

[0054] 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 axial center and a width W2 at the axial end where the step portions 12S are formed. The width W1 is the distance between the both side surfaces 12a of the teeth 12. The width W2 is the distance between the wall surfaces 12b of the two step portions 12S of the teeth 12. The widths W1 and W2 have a relationship of W1 > W2.

[0055] The insulating portion 20 has a first surface 201 which is a plane covering the end surface 12e of the tooth 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 faces the end surface 12 e 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 12 a of the tooth 12.

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

[0058] The axial dimension of the step portion 12S is defined as a height A. This height A corresponds to the distance from the bottom surface 12c of the step portion 12S to the end surface 12e of the tooth 12.

[0059] The dimension of the step portion 12S in a direction perpendicular to the axial direction on a plane perpendicular to the extension direction of the tooth 12 is defined as width B. This width B corresponds to the distance from the wall surface 12b of the step portion 12S to the side surface 12a of the tooth 12.

[0060] 6, the height A and width B of the step portion 12S of the tooth 12 satisfy the relationship A≧B. For example, 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 Fig. 6. For example, as shown in Fig. 7, the height A and width B of the step portion 12S of the teeth 12 may have a relationship of A > B. In this case, the third surface 203 extends in the axial direction to form a long elliptical arc.

[0062] 8 is an enlarged view of the periphery of the step portion 12S of the tooth 12. The first surface 201 of the insulating portion 20 covers the end surface 12e of the tooth 12 and further extends into the step portion 12S. The second surface 202 of the insulating portion 20 covers the side surface 12a of the tooth 12 and further extends into the step portion 12S.

[0063] In a plane perpendicular to the extending direction of the teeth 12, a point on the boundary between the first surface 201 and the third surface 203 is defined as point P. Also, a point on the boundary between the second surface 202 and the third surface 203 is defined as point Q.

[0064] The distance in the axial direction between points P and Q is defined as distance D1. The distance in the direction perpendicular to the axial direction between points P and Q is defined as distance D2. In other words, if the intersection 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 U, then distance D1 corresponds to the distance from point P to intersection U, and distance D2 corresponds to the distance from point Q to intersection U.

[0065] The height A and width B of the step portion 12S and the distances D1 and D2 satisfy D1≦A and D2≦B. That is, point P does not face the end surface 12e of the tooth 12, and point Q does not face the side surface 12a of the tooth 12. Therefore, the insulating portion 20 does not have a locally thin portion.

[0066] <Function> The function of the first embodiment will be described in comparison with a comparative example. Fig. 9A is a cross-sectional view showing tooth 121 and insulating portion 20C of comparative example 1. Fig. 9B is a cross-sectional view showing tooth 122 and insulating portion 20D of comparative example 2.

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

[0068] To wind the winding 30 around the insulating portion 20C without causing bulging, it is desirable for the radius of curvature of the third surface 203 to be large. However, to increase the radius of curvature of the third surface 203, it is necessary to increase the thickness t1 from the end surface 12e of the tooth 121 to the first surface 201 of the insulating portion 20C. Increasing the thickness t1 increases the circumferential length of the winding 30, and increasing the circumferential length of the winding 30 increases copper loss.

[0069] 9B shows a tooth 122 of Comparative Example 2 having a step 12S between the end face 12e and the side face 12a. The insulating portion 20D has a first surface 201 covering the end face 12e of the tooth 122, a second surface 202 facing the slot 14, and a third surface 203 between the first and second surfaces 201 and 202. The third surface 203 faces the step 12S.

[0070] Because the teeth 122 have the step portions 12S, the thickness t1 from the end faces 12e of the teeth 122 to the first surface 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] 9C is an enlarged view of the periphery of step portion 12S of tooth 122 in Comparative Example 2. In Comparative Example 2, in a plane perpendicular to the extension direction of tooth 122, point P, which is the boundary between first surface 201 and third surface 203, is located opposite end surface 12e of tooth 122. Also, point Q, which is the boundary between second surface 202 and third surface 203, is located opposite side surface 12a of tooth 122.

[0072] That is, the axial distance D1 between points P and Q, the distance D2 between points P and Q in a direction perpendicular to the axial direction, the axial height A of step portion 12S, and the width B of step portion 12S in a direction perpendicular to the axial direction satisfy D1 > A and D2 > B.

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

[0074] When such a thin portion occurs, the insulating portion 20D is more likely to break. To prevent the insulating portion 20D from breaking, it is necessary to increase the thickness t1 from the end surface 12e to the first surface 201. Therefore, the thickness t1 increases, which increases the circumferential length of the winding 30, making it difficult to reduce copper loss.

[0075] 8 , in the first embodiment, the axial distance D1 between points P and Q, the distance D2 between points P and Q in a direction perpendicular to the axial direction, the height A of step portion 12S, and the width B of step portion 12S satisfy D1≦A and D2≦B. In other words, point P does not face end face 12 e of tooth 12, and point Q does not face side face 12 a of tooth 12.

[0076] Therefore, even if the radius of curvature of the third surface 203 of the insulating portion 20 is increased, no locally thin portions of the thickness are generated. Therefore, even if the thickness t1 from the end surface 12e of the tooth 12 to the first surface 201 of the insulating portion 20 is reduced, damage to the insulating portion 20 can be prevented. This makes it possible to suppress swelling of the winding 30 by increasing the radius of curvature of the third surface 203, and to shorten the circumferential length of the winding 30 by reducing the thickness t1. As a result, copper loss can be effectively reduced.

[0077] Next, the relationship between the height A and width B of the step portion 12S will be described. Fig. 10 is a graph showing the relationship between the dimensional ratio A / B, which is the ratio of the height A to the 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 in which the height A and width B of the step portion 12S are changed so that the ratio ((A×B) / (L1×W1)) of the cross-sectional area (A×B) of the step portion 12S to the cross-sectional area (L1×W1) of the tooth 12 without the step portion 12S is constant.

[0079] 10, the torque constant increases as the value of A / B increases. The reason is as follows.

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

[0081] If the cross-sectional area of ​​the step portion 12S is constant, the width B decreases as the height A of the step portion 12S increases. As described above, the smaller the width B, the less likely magnetic saturation occurs, making it easier for the magnetic flux of 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] Since the torque constant increases as the value of A / B increases, it can be seen that, for example, a case where A / B>1 is more preferable than a case where A / B≦1. In other words, it can be seen that a configuration in which the height A and width B of the step portion 12S satisfy A>B as shown in Fig. 7 is more preferable than a configuration in which the height A and width B of the step portion 12S satisfy A≦B as shown in Fig. 6.

[0083] 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. 11 is a graph showing the relationship between the ratio A / L1 of the axial height A of the step portion 12S to the axial length L1 of the tooth 12 and the rate of change of iron loss and copper loss.

[0084] The values ​​of iron loss and copper loss were obtained by performing an analysis while changing the height A and width B so that the ratio ((A×B) / (L1×W1)) of the cross-sectional area (A×B) of the step portion 12S to the cross-sectional area (L1×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.

[0085] 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 that 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 saturation is suppressed, making it easier for magnetic flux to flow in from the rotor 5, 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 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.

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

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

[0089] In this embodiment, copper loss can be reduced by preventing the winding 30 from swelling, so a range of A / L1≦0.157 is desirable, in which the increase in iron loss is equal to or smaller than the increase in copper loss.

[0090] The electric motor 100 used in the compressor is designed according to the required specifications of the compressor, but it is desirable to use a common shape for the stator core 10 and respond to various required specifications by adjusting the width of the core back 11 or the teeth 12, or the number of turns of the winding 30, etc. In this embodiment, the shape of the stator core 10 described above can reduce copper loss and iron loss, thereby realizing a highly efficient electric motor 100 that responds to various required specifications.

[0091] Next, a description will be given of the relationship between the core back 11, the teeth 12, and the step portions 11S, 12S, and 13S of the tooth tip 13. As shown in Fig. 4, the core back 11 has a step portion 11S, the teeth 12 have a step portion 12S, and the tooth tip 13 has a step portion 13S.

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

[0093] The step 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 step portion 13S from the outer surface 13a of the tooth tip 13. Furthermore, the step portion 12S of the tooth 12 has the width B as described above.

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

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

[0096] Although an example in which stator core 10 is configured from a plurality of split cores 10A has been described here, stator core 10 is not limited to this configuration. In other words, stator core 10 may be an integrated core in which electromagnetic steel sheets punched into an annular shape are stacked in the axial direction.

[0097] In addition, although an example in which step portions 12S are formed on both circumferential sides of teeth 12 has been described here, it is sufficient that step portions 12S are formed on at least one circumferential side of teeth 12. In addition, although step portions 11S, 13S are provided on core back 11 and tooth tip 13 here, these step portions 11S, 13S do not necessarily have to be provided.

[0098] <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 insulating portions 20. The teeth 12 have end faces 12e facing the axial direction, side faces 12a facing the slots 14, and step portions 12S formed between the end faces 12e and the side faces 12a. The insulating portions 20 have first faces 201 covering the end faces 12e of the teeth 12, second faces 202 facing the slots 14, and third faces 203 which are curved or inclined faces extending from the first faces 201 to the second faces 202. In a cross section perpendicular to the extension direction of teeth 12, the boundary between first surface 201 and third surface 203 of insulating portion 20 is defined as point P, the boundary between second surface 202 and third surface 203 is defined as point Q, and 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 defined as U. The axial height A of step portion 12S, the width B of step portion 12S in a direction perpendicular to the axial direction, the distance D1 from point P to intersection point U, and the distance D2 from point Q to intersection point U satisfy D1≦A and D2≦B.

[0099] With this configuration, point P of insulating portion 20 does not face end surface 12e of tooth 12, and point Q of insulating portion 20 does not face side surface 12a of tooth 12. Therefore, even if the radius of curvature of third surface 203 of insulating portion 20 is increased, no locally thin portions are created, and stress concentration can be suppressed. This allows the thickness of insulating portion 20 to be thinned while preventing winding bulge of winding 30. In other words, the circumferential length of winding 30 can be shortened, and copper loss can be reduced.

[0100] Furthermore, since the height A and width B of the step portion 12S satisfy the relationship A>B, magnetic saturation is less likely to occur within the teeth 12, and the magnetic flux of the rotor 5 can more easily flow into the teeth 12, thereby increasing the torque constant.

[0101] In addition, since the axial height A of the step portion 12S and the axial length L1 of the stator core 10 satisfy A / L1≦0.157, increases 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 covering the end face 12 e of the tooth 12, a portion covering the side face 12 a, and a portion covering the step portion 12 S. Therefore, the insulating portion 20 can be formed in a simple process, for example, by integral molding using resin.

[0103] Furthermore, because the windings 30 are made of aluminum wire, the softness of the aluminum wire can be utilized to allow the windings 30 to be tightly wound around the teeth 12. Although aluminum wire has a higher electrical resistance than copper wire, in this embodiment the circumferential length of the windings 30 can be shortened, so that an increase in copper loss can be suppressed even when aluminum wire is used.

[0104] Second Embodiment Next, a second embodiment will be described. In the first embodiment, the step portions 12S are formed at both axial ends of the stator 1. In contrast, in the second embodiment, the step portions 12S are formed only at one axial end of the stator 1.

[0105] Fig. 12 is a diagram showing the relationship between the stator core 10 and the rotor core 50 of the electric motor of the second embodiment. In Fig. 12, the axial direction toward the compression mechanism 9 (Fig. 18) of the compressor 8 is shown as the -Z direction, and the opposite direction is shown as the +Z direction. Note that in Fig. 12, the +Z direction is upward and the -Z direction is downward, but this is not limiting.

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

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

[0108] As a result, a magnetic attractive force acts between the stator core 10 and the rotor core 50 in a direction that moves the centers of the two closer together in the axial direction. This magnetic attractive force urges the rotor 5 in the −Z direction, i.e., toward the compression mechanism 9, thereby suppressing vibration of the rotor 5.

[0109] In the second embodiment, no step portion 12S is formed at the +Z direction end of the tooth 120. On the other hand, a step portion 12S is formed at the −Z direction end of the tooth 120. The shape and dimensions of the step portion 12S are as described in the first embodiment.

[0110] The axial length of step portion 12S of tooth 120 is height A, as described in embodiment 1. The axial length of the region facing rotor core 50 within core region R1, which is at height A in the axial direction from end face 10e of stator core 10 in the −Z direction, is defined as L1.

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

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

[0113] In core region R2 of stator core 10, the proportion of the area facing rotor core 50 is large, and therefore a larger amount of magnetic flux flows in from rotor 5. Therefore, if step portion 12S is provided in core region R2 of tooth 120, magnetic saturation is more likely to occur, and iron loss may increase.

[0114] Therefore, in the second embodiment, step portions 12S are provided on teeth 120 only in core region R1 where there is little incoming magnetic flux from rotor core 50. That is, step portions 12S are provided on teeth 120 only at the ends of stator core 10 in the -Z direction. Furthermore, although not shown, step portions 11S of core back 11 and step portions 13S of tooth tips 13 are also provided only at the ends of stator core 10 in the -Z direction.

[0115] 13 is a cross-sectional view of the teeth 120 and insulating portions 20A of the second embodiment taken along a plane perpendicular to the direction in which the teeth 120 extend. As shown in FIG. 13, the ends of the teeth 120 in the -Z direction are provided with stepped portions 12S. The shape and dimensions of the stepped portions 12S are the same as those described in the first embodiment.

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

[0117] Insulating portion 20A has a first surface 201 covering end surfaces 12e of teeth 120, a second surface 202 facing slot 14, and a third surface 203 extending from first surface 201 to second surface 202. The thickness t1 from end surfaces 12e of teeth 120 to first surface 201 of insulating portion 20A is longer at the end in the +Z direction than at the end in the −Z direction.

[0118] 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.

[0119] As described above, in the second embodiment, step portions 12S are provided on teeth 120 at the end of stator core 10 in the axial direction that has a smaller area facing rotor core 50 when the axial length is the same. This makes it possible to reduce the circumferential length of windings 30 and reduce copper loss while suppressing magnetic saturation in teeth 120.

[0120] 14 is a diagram showing the relationship between the stator core 10 and the rotor core 50 in a modification of the second embodiment. In this modification, 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] In this manner, the rotor core 50 projects from the stator core 10 on both axial sides, thereby shortening the axial length of the stator core 10 and reducing the material cost of the stator core 10 .

[0122] Meanwhile, magnetic flux from the protruding portion of rotor core 50 also flows into stator core 10. Therefore, more magnetic flux from rotor core 50 flows into the end of stator core 10 in the +Z direction than into the end of stator core 10 in the −Z direction.

[0123] Therefore, in this modification, step portions 12S are provided on teeth 120 only at the −Z direction end of stator core 10 where there is little magnetic flux flowing in from rotor core 50. Although not shown, step portions 11S of core back 11 and step portions 13S of tooth tips 13 are also provided only at the −Z direction end of stator core 10.

[0124] In this modification, as in the second embodiment, the circumferential length of the winding 30 can be shortened while suppressing magnetic saturation in the teeth 120, thereby reducing copper loss.

[0125] Third Embodiment Next, a third embodiment will be described. Figure 15 is a perspective view showing teeth 12 and insulating portions 20B according to the third embodiment. The insulating portions 20B according to the third embodiment have insulators 25 that cover the end faces 12e of the teeth 12 and insulating films 26 that cover the side faces 12a of the teeth 12. Specifically, the insulators 25 are provided on both axial sides of the teeth 12, and the insulating films 26 are provided on both circumferential sides of the teeth 12.

[0126] Each insulator 25 is made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP). Each insulating film 26 is made of a resin such as polyethylene terephthalate (PET). The thickness of each 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 tooth 12 , and a flange portion 29 attached to the tooth tip portion 13 .

[0128] The wall portion 27 engages with the step 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 step portion 11S of the core back 11 is referred to as an engaging portion 27a.

[0129] The body portion 28 covers the end faces 12e of the teeth 12 and engages with the step portions 12S of the teeth 12. The portion of the body portion 28 that engages with the step portions 11S of the core back 11 is referred to as an engaging portion 28a. The body portion 28 has a first surface 201 facing the axial direction, 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 step portion 13S of the tooth tip portion 13. The portion of the flange portion 29 that engages with the step portion 13S of the tooth tip portion 13 is referred to as an engaging portion 29a.

[0131] The insulator 25 also has an extending portion 24 that extends radially outward beyond the wall portion 21. The extending portion 24 has a protrusion 24a that fits into a fitting hole 16 formed in the core back 11. The insulator 25 is fixed to the split core 10A by fitting the protrusion 24a into the fitting hole 16. Note that the insulator 25 does not necessarily have to be provided with the protrusion 24a.

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

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

[0134] 16 is a cross-sectional view of teeth 12 and insulating portion 20B of embodiment 3 taken along a plane perpendicular to the direction of extension of teeth 12. Insulating portion 20B of embodiment 3 is formed of insulator 25 and insulating film 26, which are made of different materials, and therefore it is necessary to ensure an insulation distance from stator core 10 to winding 30. The insulation 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 protrudes further in the axial direction from the side surface 12 a of the tooth 12. In other words, the insulating film 26 not only covers the side surface 12 a of the tooth 12, but also extends to partially cover the second surface 202 of the insulator 25.

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

[0137] 17 is a cross-sectional view of tooth 121 and insulating portion 20E of Comparative Example 3. Teeth 121 of Comparative Example 3 do not have a step portion. Insulating portion 20E has insulators 25 that cover end faces 12e of teeth 121 and insulating films 26 that cover side faces 12a of teeth 121.

[0138] The insulating film 26 is provided so as to protrude in the axial direction from the end surface 12e of the tooth 121. The amount of protrusion of the insulating film 26 in the axial direction from the end surface 12e of the tooth 121 is defined as D. The protrusion amount D is equal to or greater than the insulation distance described above.

[0139] If the insulating film 26 protrudes in the axial direction beyond the insulating portion 20E, there is a possibility that the insulating film 26 will bend inwardly into the slot 14 when the winding 30 is wound therearound. Therefore, the thickness t1 from the end face 12e of the tooth 121 to the first surface 201 of the insulating portion 20E must be set to be equal to or greater than the protrusion amount D, and the thickness t1 becomes large.

[0140] In contrast, in the third embodiment, teeth 12 have stepped portions 12S, so even if insulating film 26 protrudes from bottom surfaces 12c of stepped portions 12S by protrusion amount D, thickness t1 from end surfaces 12e of teeth 12 to first surface 201 can be reduced. This allows the circumferential length of winding 30 to be shortened.

[0141] As described above, in embodiment 3, the teeth 12 have step portions 12S, and the insulating portions 20 have insulating films 26 that cover the side surfaces 12a of the teeth 12. This allows the circumferential length of the windings 30 to be shortened and copper loss to be reduced while maintaining the insulation distance.

[0142] <Compressor> Next, a compressor 8 using an electric motor 100 will be described. Fig. 18 is a cross-sectional view showing the configuration of the compressor 8. The compressor 8 is a rotary compressor in this case, and includes 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 65 shown in Fig. 1 and other figures, and is fitted into the central hole 53 of the rotor 5 of the electric motor 100.

[0143] The shell 80 is a sealed container made of, for example, a 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. A glass terminal 81 serving as a terminal for supplying electric 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 are attached to the upper shell 80a. The electric motor 100 and the compression mechanism 9 are housed in the lower shell 80b.

[0144] The compression mechanism 9 has an annular first cylinder 91 and a second cylinder 92 arranged along the shaft 90. The first cylinder 91 and the second cylinder 92 are fixed to the inner periphery of the shell 80 (lower shell 80b). An annular first piston 93 is arranged on the inner periphery of the first cylinder 91, and an annular second piston 94 is arranged 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.

[0145] 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 with bolts 98.

[0146] 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 support the shaft 90 rotatably.

[0147] 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 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. Electric power 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 center hole 53 of the rotor 5 (FIG. 1).

[0149] An accumulator 87 for storing refrigerant gas is attached to the shell 80. The accumulator 87 is held by, for example, a holder 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.

[0150] As the refrigerant, for example, R410A, R407C, or R22 may be used, but from the viewpoint 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 the low GWP refrigerant.

[0151] (1) First, a halogenated hydrocarbon having a carbon-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) Alternatively, a hydrocarbon having a carbon-carbon double bond in its 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-carbon double bond in its composition or a hydrocarbon having a carbon-carbon double bond in its composition, such as a mixture of HFO-1234yf and R32, may be used. The above-mentioned HFO-1234yf is a low-pressure refrigerant and therefore tends to cause large pressure loss, which may lead to a decrease in the performance of the refrigeration cycle (especially the evaporator). Therefore, it is practically desirable to use a mixture of HFO-1234yf with R32 or R41, which are higher-pressure refrigerants than HFO-1234yf.

[0152] The basic operation of compressor 8 is as follows. Refrigerant gas supplied from accumulator 87 is supplied to each cylinder chamber of first cylinder 91 and second cylinder 92 through suction pipes 88 and 89. When electric motor 100 is driven to rotate rotor 5, shaft 90 rotates together with rotor 5. First piston 93 and second piston 94 fitted to shaft 90 then rotate eccentrically within each cylinder chamber, compressing the refrigerant within each cylinder chamber. The compressed refrigerant passes through holes 57 and 58 (FIG. 1) in rotor 5, rises within shell 80, and is discharged to the outside through discharge pipe 85.

[0153] 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.

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

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

[0156] 19 includes a compressor 401, a condenser 402 that condenses a refrigerant, a pressure reducing device 403 that reduces the pressure of the refrigerant, and an evaporator 404 that evaporates the refrigerant. The compressor 401, the condenser 402, and the pressure reducing device 403 are provided in an outdoor unit 410, and the evaporator 404 is provided in an indoor unit 420.

[0157] The compressor 401, the condenser 402, the pressure reducing device 403, and the evaporator 404 are connected by refrigerant piping 407 to form a refrigerant circuit. The compressor 401 is configured as the compressor 8 shown in Fig. 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 refrigeration cycle apparatus 400 operates as follows: The compressor 401 compresses the refrigerant it draws in and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 402 exchanges heat between the refrigerant sent out from the compressor 401 and outdoor air sent by the outdoor air blower 405, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 403 expands the liquid refrigerant sent out from the condenser 402 and sends it out as 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 by the evaporator 404 is supplied into 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 the preferred embodiments have been specifically described above, the present disclosure is not limited to the above-described embodiments, and various improvements and modifications can be made.

[0162] DESCRIPTION OF SYMBOLS 1 stator, 20, 20A, 20B insulating portion, 5 rotor, 8 compressor, 9 compression mechanism, 10 stator core, 10A split core, 11 core back, 11S step portion, 12, 120 teeth, 12S step portion, 12a side surface, 12e end surface, 13 tooth tip portion, 13S step portion, 14 slot, 15 split surface, 21 wall portion, 22 body portion, 23 flange portion, 25 insulator, 26 insulating film, 30 winding, 50 rotor core, 51 magnet insertion hole, 60 permanent magnet, 65 shaft, 80 shell, 100 electric motor, 201 first surface, 202 second surface, 203 third surface, 400 Refrigeration cycle device, 401 Compressor, 402 Condenser, 403 Pressure reducing device, 404 Evaporator

Claims

1. 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 teeth via the insulating portion; having The teeth each have an end surface facing the axial direction of the stator core, a side surface facing the 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 which is a curved surface or an inclined surface extending from the first surface to the second surface, 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. The intersection point U is located within the range of the step portion, A height A of the step portion in the axial direction, a width B of the step portion in a direction perpendicular to the axial direction, 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 are D1≦A and D2≦B are satisfied. Stator.

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

3. The height A of the step portion with respect to the axial length L1 of the tooth is, A / L1≦0.157 Satisfy The stator according to claim 2 .

4. 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 step portion is provided only in the first region of the stator core. A stator according to any one of claims 1 to 3.

5. 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 step portion is provided only on the one end side of the stator core. A stator according to any one of claims 1 to 3.

6. The insulating portion has an insulating film covering the side surfaces of the teeth. A stator according to any one of claims 1 to 3.

7. The windings are made of aluminum wire. A stator according to any one of claims 1 to 3.

8. A stator according to any one of claims 1 to 3; A rotor disposed inside the stator; An electric motor equipped with

9. An electric motor according to claim 8; a compression mechanism driven by the electric motor; A compressor equipped with

10. A compressor comprising the compressor according to claim 9, a condenser, a pressure reducing device, and an evaporator. Refrigeration cycle equipment.