Stator, electric motor, compressor, and refrigeration cycle device

Abstract

This stator comprises: a stator core having an annular core back, teeth extending radially inward from the core back, and slots adjacent to the teeth in a circumferential direction; insulation parts provided to the teeth; and windings wound around the teeth with the insulation parts interposed therebetween. The teeth each have an end surface facing in the axial direction of the stator core, side surfaces facing the slots, and step parts formed between the end surface and the side surface. The insulation parts each have an insulator that covers the end surface of the corresponding tooth, and an insulating film that covers the side surfaces of said tooth and covers part of the insulator. The step parts each have a depth D in the axial direction and a width W in a teeth width direction, where the teeth width direction is the direction orthogonal to both the extension direction and the axial direction of the teeth. Gaps are provided in the axial direction between the step parts of the teeth and the insulators. The insulating films overlap the slot side of the insulators. In a plane orthogonal to the extension direction of the teeth, the sum of the shortest distance from the contact point between the surface of the insulator facing the step parts and the insulating film to the step parts, and an overlap length L0, which is the length for which the insulating film and the insulator overlap, is equal to or greater than the insulation distance required for insulation between the stator core and the windings. At least one of 0 < D ≤ 1.25 mm and 0 < W ≤ 1.25 mm is established.

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] The stator of an electric motor includes a stator core having a plurality of teeth around which windings are wound. Slots for accommodating the windings are formed between adjacent teeth of the stator core. To insulate the stator core from the windings, insulators, which are resin molded bodies, are provided on the axial end faces of the teeth, and insulating films are provided on the inner surfaces of the slots.

[0003] For example, Patent Document 1 discloses a stator having a stepped portion at the axial end of each tooth, with a space provided in the stepped portion, in order to ensure an insulating distance between the stator core and the winding.

[0004] Japanese Patent Application Laid-Open No. 2009-89493 (see paragraph 0017, Figures 6 and 7)

[0005] However, increasing the step size to increase the insulation distance narrows the magnetic path within the teeth, which increases iron loss and reduces motor efficiency.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to suppress a decrease in motor efficiency while ensuring insulation between the stator core and the windings.

[0007] The stator of the present disclosure includes a stator core having an annular core back, teeth extending radially inward from the core back, and slots circumferentially adjacent to the teeth, 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 step portions formed between the end faces and the side faces. The insulating portions include insulators covering the end faces of the teeth and insulating films covering the side faces of the teeth and part of the insulators. If the direction perpendicular to both the extension direction and the axial direction of the teeth is defined as the tooth width direction, the step portions have a depth D in the axial direction and a width W in the tooth width direction. A gap is provided in the axial direction between the step portions of the teeth and the insulator. In a plane perpendicular to the extending direction of the teeth, the sum of the shortest distance from the contact point between the surface of the insulator facing the step portion and the insulating film to the step portion and the overlap length L0, which is the length over which the insulating film and the insulator overlap, is equal to or greater than the insulation distance required for insulation between the stator core and the windings. At least one of 0 < D ≦ 1.25 mm and 0 < W ≦ 1.25 mm is satisfied.

[0008] According to the present disclosure, the sum of the shortest distance from the contact point between the surface of the insulator facing the step portion and the insulating film to the step portion and the overlap length L0 is equal to or greater than the insulation distance, and at least one of 0 < D ≦ 1.25 mm and 0 < W ≦ 1.25 mm is satisfied with respect to the depth D and width W of the step portion. This ensures that the stator core and the windings are insulated, and that the magnetic path within the teeth is secured to suppress increases in iron loss, thereby suppressing decreases in motor efficiency.

[0009] 1 is a cross-sectional view showing an electric motor according to a first embodiment; FIG. 2 is a plan view showing a rotor according to the first embodiment; FIG. 3 is a plan view showing a stator core of the electric motor according to the first embodiment; FIG. 4 is a perspective view showing a stator core, insulator, and insulating film according to the first embodiment; FIG. 5 is a cross-sectional view showing teeth, insulator, and insulating film according to the first embodiment; FIG. 6 is a cross-sectional view showing teeth, insulator, insulating film, and windings according to the first embodiment; FIG. 7 is a cross-sectional view showing step portions of teeth and the surrounding insulator and insulating film according to the first embodiment; FIG. 8 is a cross-sectional view showing teeth, insulator, and insulating film according to a first comparative example; FIG. 9 is a cross-sectional view showing teeth, insulator, insulating film, and windings according to the first comparative example; FIG. 10 is a cross-sectional view showing teeth, insulator, and insulating film according to a second comparative example; 1A is a cross-sectional view showing the teeth, insulator, insulating film, and windings of embodiment 2, and FIG. 1B is a cross-sectional view showing the step portion of the tooth and the surrounding insulator and insulating film. FIG. 1B is a graph showing the relationship between the width of the step portion of the tooth and the rate of increase in iron loss. FIG. 1C is a graph showing the relationship between the width of the step portion of the tooth and the rate of increase in copper loss. FIG. 1D is a graph showing the relationship between the width of the step portion of the tooth and the rate of increase in total loss. FIG. 1E is a cross-sectional view showing the teeth, insulator, and insulating film of embodiment 3. FIG. 1F is a cross-sectional view showing the step portion of the tooth and the surrounding insulator and insulating film in embodiment 3. FIG. 1G is a cross-sectional view showing the step portion of the tooth and the surrounding insulator and insulating film in embodiment 3. FIG. 1H is a cross-sectional view showing the step portion of the tooth and the surrounding insulator and insulating film in embodiment 4. FIG. 1A is a schematic diagram for explaining a method of winding the windings onto the insulating film of embodiment 4, and FIG. 1B is a perspective view showing the entire insulating film arranged in one slot. FIG. 1H is a diagram for explaining the tension acting on the windings on the insulator. FIG. 1I is a cross-sectional view showing the step portion of the tooth and the surrounding insulator and insulating film in embodiment 5. A cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film in a modified example of embodiment 5.36 is a cross-sectional view showing a tooth, an insulator, and an insulating film according to a sixth embodiment. FIG. 37 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to a seventh embodiment. FIG. 38 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to the seventh embodiment. FIG. 39 is a cross-sectional view showing a tooth, an insulator, and an insulating film according to an eighth embodiment. FIG. 39 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to the eighth embodiment. FIG. 39 is a cross-sectional view showing a tooth, an insulator, and an insulating film according to a ninth embodiment. FIG. 39 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to the ninth embodiment. FIG. 39 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to the tenth embodiment. FIG. 39 is a cross-sectional view showing a step portion of a tooth and the surrounding insulator and insulating film according to another configuration example of ... longitudinal cross-sectional view showing a compressor to which the electric motors of the respective embodiments and modified examples can be applied. FIG. 39 is a diagram showing a refrigeration cycle device to which the compressor of FIG.

[0010] First Embodiment <Configuration of Electric Motor> First, an electric motor 3 according to the first embodiment will be described. Fig. 1 is a cross-sectional view showing the electric motor 3 according to the first embodiment. The electric motor 3 shown in Fig. 1 is a permanent magnet embedded synchronous motor, and is used in, for example, a compressor 8 (Fig. 36).

[0011] The electric motor 3 has a shaft 90 which is a rotating shaft, a rotor 5 fixed to the shaft 90, 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 frame 81 of a compressor 8 (FIG. 36) which will be described later.

[0012] Hereinafter, the direction of the center axis Ax of the rotor 5, i.e., the center axis of the shaft 90, will be referred to as the "axial direction." The radial direction centered on the central axis Ax will be referred to as the "radial direction." The circumferential direction centered on the central axis Ax will be referred to as the "circumferential direction."

[0013] <Configuration of the Rotor> Fig. 2 is a cross-sectional view showing the rotor 5. The rotor 5 has an annular rotor core 50 centered on the central axis Ax, and permanent magnets 55 attached to the rotor core 50. The rotor core 50 has a plurality of laminated elements stacked in the axial direction. The laminated elements are, for example, electromagnetic steel sheets. The plate thickness of the laminated elements is 0.1 to 0.7 mm.

[0014] A center hole 53 is formed in the radial center of the rotor core 50. A shaft 90 (FIG. 1) is fixed in the center hole 53 of the rotor core 50 by shrink fitting, press fitting, or the like.

[0015] A plurality of magnet insertion holes 51 are formed along the outer periphery of the rotor core 50. One permanent magnet 55 is placed in each magnet insertion hole 51. One magnet insertion hole 51 corresponds to one magnetic pole. Because the rotor core 50 has six magnet insertion holes 51, the rotor 5 has six poles. However, the number of poles of the rotor 5 is not limited to six, as long as it is two or more. Furthermore, two or more permanent magnets 55 may be placed in each magnet insertion hole 51.

[0016] The permanent magnets 55 have a width in the circumferential direction of the rotor core 50 and a thickness in the radial direction. Each permanent magnet 55 is magnetized in the thickness direction. The permanent magnets 55 are made of a rare earth magnet containing, for example, neodymium (Nd), iron (Fe), and boron (B).

[0017] Dysprosium (Dy) may be added to rare earth magnets to improve coercivity. However, adding Dy increases manufacturing costs and reduces remanence, so it is desirable to keep the Dy content at 4% by weight or less, or to add no Dy at all. In other words, the Dy content is desirably 0 to 4% by weight.

[0018] The circumferential center of the magnet insertion hole 51 is the pole center Pc. A radial line passing through the pole center Pc is called the pole center line. An inter-pole portion Ip is formed between adjacent magnetic poles. In this example, the magnet insertion hole 51 extends linearly in a direction perpendicular to the pole center line. However, the magnet insertion hole 51 may also extend in a V-shape.

[0019] Flux barriers 52, which are gaps, are formed on both circumferential sides of the magnet insertion holes 51. Thin-walled portions are formed between the flux barriers 52 and the outer periphery of the rotor core 50. In order to reduce leakage flux between adjacent magnetic poles, the radial width of the thin-walled portions is set to be the same as the plate thickness of the laminated elements, for example.

[0020] Radially long slits 54 are formed on the radially outer side of the magnet insertion holes 51. The slits 54 are formed to control the magnetic flux density distribution on the surface of the rotor 5. Here, seven slits 54 are formed symmetrically with respect to the pole center line, but the number and arrangement of the slits 54 are arbitrary. Also, the rotor core 50 does not necessarily have to be provided with slits 54.

[0021] The crimping portions 56 that secure the laminated elements are formed at circumferential positions corresponding to the inter-polar portions Ip, radially inward of the flux barriers 52. However, the placement of the crimping portions 56 is not limited to these positions. Furthermore, the laminated elements of the rotor core 50 may be secured by a method other than crimping.

[0022] Through holes 57 and 58 are formed radially inside the magnet insertion holes 51. The circumferential position of the through hole 57 coincides with the pole center Pc, and the circumferential position of the through hole 58 coincides with the inter-pole portion Ip. The through holes 57 and 58 penetrate the rotor core 50 in the axial direction and are used as refrigerant passages. Note that the arrangement of the through holes 57 and 58 is not limited to the positions described here. Furthermore, the rotor core 50 does not necessarily have to have the through holes 57 and 58.

[0023] <Configuration of Stator> As shown in Fig. 1, the stator 1 has a stator core 10 that surrounds the rotor core 50 from the radial outside, and a winding 30 wound around the stator core 10. The stator core 10 has a plurality of laminated elements that are laminated in the axial direction. The laminated elements are, for example, electromagnetic steel sheets. The plate thickness of the laminated elements is 0.1 to 0.7 mm.

[0024] Fig. 3 is a plan view showing the stator core 10, and also shows a frame 81. As shown in Fig. 3, the stator core 10 has an annular core back 11 centered on the central axis Ax, and N (N is an integer of 2 or more) teeth 12 extending radially inward from the core back 11. The teeth 12 are arranged at regular intervals in the circumferential direction. Here, the number N of the teeth 12 is 9, but it may be any number equal to or greater than 2.

[0025] The teeth 12 have extending portions 121 extending radially inward from the core back 11 and tooth tips 122 formed at the tips of the extending portions 121. The circumferential width of the tooth tips 122 is wider than the circumferential width of the extending portions 121. The tooth tips 122 face the rotor 5 (FIG. 2). A radial line passing through the circumferential center of the tooth 12 is defined as a tooth center line Tc.

[0026] A slot 13 is formed between circumferentially adjacent teeth 12. The slot 13 is an area that houses the winding 30. The number of slots 13 is N, which is the same as the number of teeth 12, and is nine in this example.

[0027] The windings 30 (FIG. 1) are made of magnet wire and wound in concentrated winding around each tooth 12. A current having a frequency corresponding to the rotational speed of the electric motor 3 flows through the windings 30, generating a rotating magnetic field that rotates the rotor 5.

[0028] The wire diameter of the winding 30 and the number of turns around one tooth 12 are determined by the required specifications such as rotational speed and torque, the supply voltage, and the cross-sectional area of ​​the slot 13. As an example, the wire diameter of the winding 30 is 1.0 mm and the number of turns is 80. An insulating portion is provided between the stator core 10 and the winding 30, and the insulating portion will be described later.

[0029] The stator core 10 is divided into N split cores 14 by dividing surfaces 111 formed on the core back 11. Each split core 14 includes one tooth 12. The portion of the core back 11 included in each split core 14 is also referred to as a core back portion 110. Circumferentially adjacent split cores 14 are connected by crimping portions 112 provided on the outer periphery of the dividing surfaces 111 or by welding.

[0030] When manufacturing the stator 1, the N split cores 14 of the stator core 10 are spread out linearly, and a winding nozzle is used to wind the windings 30 around the teeth 12. After the windings 30 are wound around the teeth 12, the N split cores 14 are bent into an annular shape, and the split cores 14 at both ends are fixed by welding or the like to form the annular stator core 10.

[0031] The stator core 10 is not limited to being formed by combining N split cores 14 in an annular shape, but may be, for example, an integral core formed by laminating annular electromagnetic steel plates in the axial direction.

[0032] 4 is a schematic diagram showing a part of the stator core 10 (i.e., the split core 14) and an insulating portion. In FIG. 4, the direction of the central axis Ax (FIG. 1), i.e., the axial direction, is indicated by an arrow Z.

[0033] 4 , the core back 11 has an end face 11e facing the axial direction and an inner circumferential surface 11a facing the slot 13. The teeth 12 have end faces 12e facing the axial direction and side faces 12a facing the slot 13.

[0034] The end faces 11e of the core back 11 and the end faces 12e of the teeth 12 are on the same plane and correspond to the end faces of the stator core 10. These end faces 11e, 12e are perpendicular to the axial direction. The inner circumferential surface 11a of the core back 11 and the side faces 12a of the teeth 12 form the inner surfaces of the slots 13. These inner circumferential surfaces 11a and side faces 12a are parallel to the axial direction.

[0035] 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 bottom surface 12b facing the axial direction and a wall surface 12c facing the slot 13. The bottom surface 12b is perpendicular to the axial direction, and the wall surface 12c is parallel to the axial direction.

[0036] 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 bottom surface 11b facing the axial direction and a wall surface 11c facing the slot 13. The bottom surface 11b is perpendicular to the axial direction, and the wall surface 11c is parallel to the axial direction.

[0037] The split core 14 is composed of a first core portion A1 stacked in the axial center and second core portions A2 stacked on both axial ends. The second core portion A2 has a narrower core back 11 width and a narrower tooth 12 width than the first core portion A1.

[0038] Insulators 20 are provided on both axial ends of the split core 14. The insulators 20 are made of a resin such as polybutylene terephthalate (PBT) or liquid crystal polymer (LCP). Note that while Fig. 4 shows only the insulator 20 at one axial end of the split core 14, the insulator 20 at the other end is configured in the same way.

[0039] Each insulator 20 has a wall portion 21 attached to the core back 11, a body portion 22 attached to the extension portion 121 of the tooth 12, and a flange portion 23 attached to the tooth tip portion 122. The wall portion 21 and the flange portion 23 face each other in the radial direction.

[0040] The wall portion 21 is located on the end face 11e of the core back 11 and extends in the axial direction. The body portion 22 covers the end face 12e of the extension portion 121 of the tooth 12. The flange portion 23 is located on the end face 12e of the tip portion 122 of the tooth 12 and extends in the axial direction.

[0041] The insulator 20 also has a protrusion (not shown) that fits into the fitting hole 16 formed in the core back 11. The insulator 20 is fixed to the split core 14 by fitting the protrusion of the insulator 20 into the fitting hole 16 of the core back 11. Note that the insulator 20 may be fixed to the split core 14 by a method other than fitting the protrusion into the fitting hole 16.

[0042] An insulating film 25 is provided to cover the inner peripheral surface 11a of the core back 11 and the side surfaces 12a of the teeth 12. The insulating film 25 is a film made of a resin such as polyethylene terephthalate (PET), and has a thickness of 0.1 to 0.3 mm, for example.

[0043] A winding 30 is wound around the body portion 22 and the insulating film 25 of the insulator 20. The wall portion 21 and the flange portion 23 of the insulator 20 guide the winding 30 from both sides in the radial direction.

[0044] 5 is a cross-sectional view showing the teeth 12, the insulator 20, and the insulating film 25, taken along a plane perpendicular to the extension direction of the teeth 12. The direction perpendicular to both the extension direction of the teeth 12 (the direction of the tooth center line Tc shown in FIG. 3) and the axial direction is defined as the "tooth width direction."

[0045] The insulator 20 covers the end faces 12e of the teeth 12. The insulator 20 has a top surface 201 facing away from the teeth 12 in the axial direction, a side surface 202 facing the slot 13, and a curved surface 203 extending from the top surface 201 to the side surface 202. The top surface 201 is also referred to as a first surface, the side surface 202 is also referred to as a second surface, and the curved surface 203 is also referred to as a third surface.

[0046] The insulator 20 has a thickness T in the axial direction. The thickness T is the distance from the end surface 12 e of the tooth 12 to the top surface 201 of the insulator 20.

[0047] The insulating film 25 covers the side surfaces 12a of the teeth 12. The insulating film 25 also covers the side surfaces 202 of the insulators 20, as will be described later.

[0048] 4, the teeth 12 have step portions 12S between the end faces 12e and the side faces 12a. The step portions 12S have bottom faces 12b facing the axial direction and wall faces 12c facing the slots 13.

[0049] 6 is a cross-sectional view of the teeth 12, the insulators 20, the insulating films 25, and the windings 30 taken along a plane perpendicular to the direction in which the teeth 12 extend. The windings 30 are wound around the teeth 12 with the insulators 20 and the insulating films 25 interposed therebetween.

[0050] A winding bulge H1 occurs between the winding 30 and the insulating film 25. The winding bulge H1 is maximum at the center of the insulating film 25 in the axial direction. Furthermore, a winding bulge H2 occurs between the winding 30 and the top surface 201 of the insulator 20. The winding bulge H2 is maximum at the center of the top surface 201 in the tooth width direction.

[0051] 7 is a cross-sectional view showing the step portion 12S of the tooth 12 and the surrounding insulator 20 and insulating film 25. The step portion 12S has an axial depth D. The depth D is the axial distance from the bottom surface 12b of the step portion 12S to the end surface 12e of the tooth 12.

[0052] The step portion 12S has a width W in the tooth width direction (i.e., a direction perpendicular to the extension direction and axial direction of the tooth 12). The width W is the distance from the wall surface 12c of the step portion 12S to the side surface 12a of the tooth 12.

[0053] Furthermore, a gap is provided between the bottom surface 12b of the step portion 12S and the insulator 20. The gap is a space portion. The axial length of the gap is defined as the gap length L1. The gap length L1 is the axial distance from the bottom surface 12b of the step portion 12S to the insulator 20. In the example shown in FIG. 7 , the gap length L1 is equal to the depth D of the step portion 12S (D = L1).

[0054] 15B, when a portion of the insulator 20 protrudes toward the stepped portion 12S, the gap length L1 becomes shorter than the depth D of the stepped portion 12S (L1<D). This will be described in the second embodiment.

[0055] The insulating film 25 covers the side surfaces 12a of the teeth 12, passes through the step portions 12S, and overlaps the slot 13 side of the insulator 20. The portion of the insulating film 25 that overlaps with the insulator 20 is referred to as an overlap portion 25a.

[0056] In a cross section perpendicular to the direction in which the teeth 12 extend, the length over which the insulating film 25 and the insulator 20 overlap, i.e., the length of the overlapping portion 25a, is referred to as an overlap length L0.

[0057] Although the overlapping portion 25a of the insulating film 25 is in contact with the side surface 202 of the insulator 20 in FIG. 7, it may also be in contact with the curved surface 203 (see FIG. 24).

[0058] <Comparative Example 1> Fig. 8 is a cross-sectional view taken along a plane perpendicular to the extension direction of the tooth 12H, showing the tooth 12H, insulator 20, and insulating film 25 of Comparative Example 1. Fig. 9 is a cross-sectional view showing the state in which the winding 30 is wound around the tooth 12H of Comparative Example 1. In Figs. 8 and 9, the components of Comparative Example 1 are given the same reference numerals as those of the first embodiment.

[0059] 8, tooth 12H of Comparative Example 1 does not have a step between side surface 12a and end surface 12e. That is, a 90-degree corner is formed between side surface 12a and end surface 12e of tooth 12H.

[0060] Insulation between the stator core 10 and the windings 30 is achieved by insulators 20 covering the end faces 12e of the teeth 12H and insulating films 25 covering the side faces 12a of the teeth 12H. The insulating films 25 overlap the insulators 20 in areas that protrude axially beyond the end faces 12e of the teeth 12H.

[0061] If the side surfaces 12a of the teeth 12H were covered with a resin molded body similar to the insulator 20, the resin molded body would have to be molded to a uniform thickness, which would increase manufacturing costs. In Comparative Example 1, the side surfaces 12a of the teeth 12H are covered with insulating film 25, which reduces manufacturing costs. Furthermore, because insulating film 25 is thinner than the resin molded body, it is possible to expand the winding area within slot 13 and improve motor efficiency.

[0062] Here, the overlap length L0, which is the length over which the insulating film 25 and the insulator 20 overlap, is set to be equal to or greater than the insulation distance required for insulation between the stator core 10 and the windings 30. The insulator 20 needs to have a sufficient thickness T to ensure the overlap length L0.

[0063] The thicker the thickness T of the insulator 20, the greater the circumferential length of the winding 30. The circumferential length of the winding 30 refers to the length of one turn of the winding 30 wound around one tooth 12H. Because the portion of the winding 30 wound around the insulator 20 does not contribute to torque generation, the thicker the thickness T of the insulator 20, the longer the portion of the winding 30 that does not contribute to torque generation.

[0064] The windings 30 are made of copper or aluminum wire, but because the price of copper wire has risen sharply with increasing demand for electric vehicle motors, the manufacturing cost increases significantly as the perimeter of the windings 30 increases. Furthermore, because aluminum wire has a higher electrical resistance than copper wire, the copper loss increases as the perimeter of the windings 30 increases.

[0065] <Comparative Example 2> Fig. 10 is a cross-sectional view taken along a plane perpendicular to the extension direction of the teeth 12, showing the teeth 12, insulators 20H, and insulating films 25 of Comparative Example 2. Fig. 11 is a cross-sectional view showing the state in which the windings 30 are wound around the teeth 12 of Comparative Example 2. In Fig. 11, the components of Comparative Example 2 are given the same reference numerals as those of the first embodiment.

[0066] 11 , in Comparative Example 2, similar to Embodiment 1, a step 12S is provided between the end face 12e and the side face 12a of the tooth 12. The step 12S has a depth D in the axial direction and a width W in the tooth width direction.

[0067] The insulator 20H has a thin portion 20T that protrudes toward the step portion 12S beyond the end face 12e of the tooth 12. The thin portion 20T is formed to contact the bottom surface 12b and wall surface 12c of the step portion 12S. In other words, no gap exists between the step portion 12S and the insulator 20H.

[0068] The insulating film 25 overlaps the insulator 20H including the thin-walled portion 20T. An overlap length L0, which is the length by which the insulating film 25 and the insulator 20H overlap, is set to be equal to or greater than the insulation distance required for insulating the stator core 10 from the windings 30.

[0069] In Comparative Example 2, the axial length of thin-walled portion 20T of insulator 20H is included in overlap length L0. Therefore, by increasing the axial length (i.e., the amount of protrusion) of thin-walled portion 20T, thickness T of insulator 20H can be reduced, and the circumferential length of winding 30 can be shortened.

[0070] On the other hand, in order to increase the axial length of the thin-walled portion 20T, it is necessary to increase the depth D of the step portion 12S of the tooth 12. If the depth D of the step portion 12S is increased, the magnetic path inside the tooth 12 becomes narrower, which increases the magnetic resistance inside the tooth 12 and may increase iron loss.

[0071] Furthermore, if the depth D of the step portion 12S is increased, magnetic saturation may occur around the step portion 12S, which may reduce the torque constant. If the torque constant is reduced, the amount of current required to generate a desired torque may increase, which may increase copper loss.

[0072] <Function of First Embodiment> In contrast, in the first embodiment, as shown in Fig. 7, a gap is provided between the bottom surface 12b of the step portion 12S of the tooth 12 and the insulator 20. The length of overlap between the insulating film 25 and the insulator 20, i.e., the overlap length L0, corresponds to the creepage distance. The creepage distance refers to the length along the surface of the insulator between two objects to be insulated.

[0073] Here, the point of contact between the insulating film 25 and the opposing surface 204 of the insulator 20 facing the step portion 12S is defined as P. The shortest distance from the point of contact P to the step portion 12S corresponds to the spatial distance. The spatial distance is the shortest distance passing through the space between two objects to be insulated.

[0074] The shortest distance from the contact point P to the step portion 12S is the shorter of the distance from the contact point P to the bottom surface 12b and the distance from the contact point P to the wall surface 12c. The distance from the contact point P to the bottom surface 12b is the gap length L1. Although the gap length L1 is longer than 0 mm, it does not exceed the depth D of the step portion 12S, and therefore falls within the range of 0 < L1 ≦ D. The distance from the contact point P to the wall surface 12c is the width W of the step portion 12S. Therefore, the shorter of the gap length L1 and the width W of the step portion 12S corresponds to the spatial distance.

[0075] The sum of the creepage distance and the clearance distance is set to be equal to or greater than the insulation distance required for insulation between the stator core 10 and the windings 30. The insulation distance required for insulation between the stator core 10 and the windings 30 is determined by the safety standards of the country in which the electric motor 3 is used.

[0076] The Electrical Appliance and Material Safety Act, a Japanese safety standard, requires that the insulation distance between the stator core and windings in an air conditioner motor be 2.0 mm or more. In the United States, for example, the UL standard established by the Underwriters Laboratories requires that the insulation distance be 1.0 mm or more.

[0077] In the first embodiment, it is sufficient that the sum of the overlap length L0 between the insulating film 25 and the insulator 20 and the smaller of the gap length L1 and the width W of the step portion 12S is equal to or greater than the required insulation distance. That is, it is sufficient that L0 + L1 or L0 + W is equal to or greater than the required insulation distance (e.g., 2.0 mm or greater).

[0078] Therefore, the overlap length L0 can be made shorter than the required insulation distance, which allows the depth D of the step portion 12S to be made shallower than in Comparative Example 2 (FIG. 11), thereby suppressing an increase in magnetic resistance.

[0079] Furthermore, since it is not necessary to increase the thickness T of the insulator 20 as in the comparative example 1 (FIG. 9), the circumferential length of the winding 30 can be shortened.

[0080] Here, the insulation distance required for insulation between the stator core 10 and the windings 30 in the electric motor 3 is determined by the drive voltage, etc., rather than the size of the electric motor 3, and is therefore constant regardless of the axial length of the stator core 10.

[0081] 12 and 13 are graphs showing the analysis results of the change in loss when the dimensions of the step portion 12S are changed. In the analysis, the depth D and width W of the step portion 12S are set to the same value (D = W), and these are changed from 0.00 mm to 2.00 mm. The axial length of the stator core 10 is set to three different values: 25 mm, 35 mm, and 45 mm. The gap length L1 is set to the same value as the depth D and width W of the step portion 12S (i.e., D = W = L1).

[0082] 12 shows the relationship between the dimensions of the step portion 12S and the rate of increase in iron loss. The horizontal axis represents the depth D and width W of the step portion 12S, and the vertical axis represents the rate of increase in iron loss. The rate of increase in iron loss is a relative value of the iron loss based on the iron loss when D = W = 0.

[0083] 13 shows the relationship between the dimensions of the step portion 12S and the copper loss increase rate. The horizontal axis represents the depth D and width W of the step portion 12S, and the vertical axis represents the copper loss increase rate. The copper loss increase rate is a relative value of the copper loss based on the copper loss when D = W = 0.

[0084] As shown in Fig. 12, the increase in iron loss due to the provision of the step portion 12S becomes more pronounced as the axial length of the stator core 10 becomes shorter. Also, as shown in Fig. 13, the increase in copper loss due to the provision of the step portion 12S becomes more pronounced as the axial length of the stator core 10 becomes shorter. This is because the proportion of the step portion 12S in the cross section of the tooth 12 increases as the axial length of the stator core 10 becomes shorter.

[0085] FIG. 14 is a graph showing the increase rates of iron loss and copper loss when the axial length of the stator core 10 is set to 25 mm, among the analysis results shown in FIGS.

[0086] 14, iron loss increases as the depth D and width W of the step portion 12S increase, but the gradient becomes gentler once the depth D and width W reach 1.25 mm. On the other hand, copper loss increases as the depth D and width W of the step portion 12S increase, and the gradient becomes even steeper once the depth D and width W reach 1.25 mm.

[0087] That is, in both the curve showing the change in iron loss and the curve showing the change in copper loss, the point where the depth D and width W of the step portion 12S are 1.25 mm is an inflection point.

[0088] This is because when the depth D and width W of the step portion 12S exceed 1.25 mm, magnetic saturation occurs within the teeth 12. When magnetic saturation occurs, iron loss is saturated, but because magnetic saturation occurs and the torque constant decreases, the amount of current required to generate the desired torque increases, and copper loss increases.

[0089] These results show that if at least one of the depth D and width W of the step portion 12S is 1.25 mm or less, the effect of suppressing the occurrence of magnetic saturation within the teeth 12 is achieved, and if both the depth D and width W of the step portion 12S are 1.25 mm or less, the effect of suppressing the occurrence of magnetic saturation is particularly high.

[0090] Furthermore, in each of the curves shown in FIGS. 12 and 13 when the axial length of the stator core 10 is 35 mm and 45 mm, the inflection point is the point where the depth D and width W of the step portion 12S are 1.25 mm. This shows that if at least one (more preferably both) of the depth D and width W of the step portion 12S is 1.25 mm or less, the occurrence of magnetic saturation can be suppressed and increases in iron loss and copper loss can be suppressed.

[0091] That is, by making the sum of the shortest distance (i.e., clearance distance) from the contact P between the insulating film 25 and the opposing surface 204 of the insulator 20 facing the stepped portion 12S to the stepped portion 12S and the overlap length L0 (i.e., creepage distance) equal to or greater than the required insulation distance, the depth D of the stepped portion 12S can be made relatively shallow, thereby suppressing an increase in magnetic resistance within the tooth 12. In addition, by satisfying at least one of (more preferably both of) 0<D≦1.25 mm and 0<W≦1.25 mm, magnetic saturation within the tooth 12 can be suppressed.

[0092] The step portions 12S of the teeth 12 preferably have a depth D equal to or greater than the width W (i.e., D≧W), and more preferably have a depth D greater than the width W (i.e., D>W). The reason for this will be explained in the second embodiment with reference to FIGS. 16 to 18.

[0093] Next, the thermal shrinkage of the insulating film 25 will be described. The insulating film 25 made of a resin such as PET has the property of shrinking due to heat. The thermal expansion coefficient α of the insulating film 25 is 60×10 －６ / °C≦α≦120×10 －６ / °C.

[0094] Heat is generated in the stator 1 by energizing the windings 30, and the amount of heat generated varies depending on the specifications or operating conditions of the motor 3. Therefore, an allowable temperature range for the windings 30 is generally set according to the specifications of the motor 3, and the motor 3 is operated so that the temperature of the windings 30 does not exceed the upper limit temperature Tmax of the allowable temperature range.

[0095] On the other hand, even if the temperature of the winding 30 is equal to or lower than the upper limit temperature Tmax, the amount of thermal contraction of the insulating film 25 varies depending on the temperature, and the insulation distance described above changes.

[0096] Therefore, it is conceivable to set the insulation distance assuming that the winding 30 is heated to the upper limit temperature Tmax (i.e., when the insulating film 25 has undergone the greatest thermal shrinkage). Alternatively, it is conceivable to prepare a plurality of types of stators 1 with different dimensions of the insulating film 25, and select the optimum stator 1 in consideration of the specifications and operating conditions of the electric motor 3.

[0097] 5, in the first embodiment, a spatial distance is ensured by a gap between the step portion 12S of the tooth 12 and the insulator 20. Therefore, it is desirable that the minimum width W of the step portion 12S be equal to or greater than X / 2, which is half the maximum axial contraction amount X of the insulating film 25 (i.e., W≧X / 2).

[0098] If the axial length of the insulating film 25 at room temperature (20°C) is Li (mm), the thermal expansion coefficient of the insulating film 25 is α, and the upper limit temperature of the allowable temperature range is Tmax, the maximum axial contraction amount X (mm) of the insulating film 25 is expressed as X = Li × α × (Tmax - 20).

[0099] Therefore, it is desirable that the width W of the step portion 12S satisfies W≧Li×α×(Tmax−20) / 2, so that the reduction in creepage distance (more specifically, the reduction in overlap length L0) due to thermal contraction on each side of the insulating film 25 in the axial direction can be compensated for by the width W of the step portion 12S.

[0100] 7 may be provided at least at one axial end of stator core 10, and a different structure may be used to provide insulation at the other end. Also, an inclined surface (see FIG. 25) may be provided instead of curved surface 203 of insulator 20.

[0101] Effects of the Embodiment As described above, the stator 1 according to the first embodiment includes a stator core 10 having an annular core back 11, teeth 12 extending radially inward from the core back 11, and slots 13 circumferentially adjacent to the teeth 12, insulating portions provided on the teeth 12, and windings 30 wound around the teeth 12 via the insulating portions. The teeth 12 have end faces 12e facing the axial direction, side faces 12a facing the slots 13, and step portions 12S formed between the end faces 12e and the side faces 12a. The insulating portions include insulators 20 provided on the end faces 12e of the teeth 12 and insulating films 25 covering the side faces 12a of the teeth 12 and part of the insulators 20. The step portions 12S have a depth D in the axial direction and a width W in the tooth width direction (i.e., a direction perpendicular to both the extension direction of the teeth 12 and the axial direction). An axial gap is provided between the step portion 12S and the insulator 20. In a plane perpendicular to the extension direction of the tooth 12, the sum of the shortest distance from a contact point P between the insulating film 25 and the opposing surface 204 of the insulator 20 facing the step portion 12S to the step portion 12S and an overlap length L0, which is the length over which the insulating film 25 and the insulator 20 overlap, is equal to or greater than the insulation distance (e.g., 2.0 mm) required for insulation between the stator core 10 and the winding 30. The depth D and width W of the step portion 12S satisfy at least one of 0 < D ≦ 1.25 mm and 0 < W ≦ 1.25 mm.

[0102] In this way, the sum of the shortest distance from contact P to step portion 12S (i.e., the clearance distance) and overlap length L0 (i.e., the creepage distance) is equal to or greater than the insulation distance, so insulation between stator core 10 and winding 30 can be ensured even if step portion 12S has a relatively shallow depth D. This prevents an increase in magnetic resistance within tooth 12 and reduces a decrease in motor efficiency. Furthermore, by satisfying at least one of (more preferably both of) 0 < D ≦ 1.25 mm and 0 < W ≦ 1.25 mm regarding the depth D and width W of step portion 12S, magnetic saturation in tooth 12 is suppressed, thereby preventing an increase in iron loss and copper loss and a decrease in motor efficiency.

[0103] Furthermore, in embodiment 1, the depth D of the step portion 12S and the gap length L1 are the same (i.e., D = L1), so the shape of the insulator 20 can be simplified, thereby simplifying the molding process of the insulator 20.

[0104] Embodiment 2. Fig. 15(A) is a cross-sectional view showing tooth 12, insulator 20A, insulating film 25, and winding 30 according to embodiment 2. In embodiment 2, as shown in Fig. 15(A), insulator 20A has thin-walled portion 20T that protrudes toward stepped portion 12S.

[0105] 15B is a cross-sectional view showing step portion 12S of tooth 12 and the surrounding insulator 20A and insulating film 25. As described in the first embodiment, step portion 12S has a depth D in the axial direction and a width W in the tooth width direction.

[0106] The thin portion 20T of the insulator 20A protrudes so as to face the wall surface 12c of the step portion 12S of the tooth 12. The portion of the insulator 20A other than the thin portion 20T is also referred to as a main body portion.

[0107] A gap is formed between the bottom surface 12b of the step portion 12S and the thin-walled portion 20T of the insulator 20A. Because the insulator 20A has the thin-walled portion 20T, the axial length of the gap between the bottom surface 12b of the step portion 12S and the insulator 20A, i.e., the gap length L1, is shorter than the depth D of the step portion 12S. That is, 0<L1<D holds.

[0108] The insulating film 25 contacts the side surface 202 of the insulator 20A. The length of the side surface 202 of the insulator 20A is longer than that of the first embodiment by the amount of protrusion of the thin-walled portion 20T. Therefore, the overlap length L0, which is the length over which the insulating film 25 and the insulator 20A overlap, is longer than that of the first embodiment.

[0109] The point of contact between insulating film 25 and opposing surface 205 of thin portion 20T facing stepped portion 12S is designated as P. The shortest distance from contact point P to stepped portion 12S corresponds to the spatial distance. In other words, the shorter of width W of stepped portion 12S and gap length L1 corresponds to the spatial distance.

[0110] The sum of the creepage distance and the spatial distance is set to be equal to or greater than the insulation distance required for insulation between the stator core 10 and the windings 30. In other words, the shorter of L0+W and L0+L1 is set to be equal to or greater than the required insulation distance.

[0111] Here, we will explain the shape of the step portion 12S of the tooth 12, that is, the relationship between the depth D and the width W. Figures 16 to 18 are graphs showing the analysis results of the change in loss when the product of the depth D and the width W of the step portion 12S is kept constant and the width W of the step portion 12S is changed.

[0112] In the analysis, the product of the depth D and width W of the step portion 12S was kept constant at 1.25 mm × 1.25 mm, and the width W of the step portion 12S was varied from 0.25 mm to 1.25 mm. The axial length of the stator core 10 was also varied in three ways: 25 mm, 35 mm, and 45 mm.

[0113] Furthermore, gap length L1 is set to be the same as depth D and width W of step portion 12S (i.e., L1 = D = W). That is, insulator 20A is shaped so as not to protrude beyond end face 12e of tooth 12 toward step portion 12S, as shown in FIG. 7 of the first embodiment.

[0114] 16 shows the relationship between the width W of the step portion 12S and the rate of increase in iron loss. The horizontal axis represents the width W of the step portion 12S, and the vertical axis represents the rate of increase in iron loss. The rate of increase in iron loss is a relative value of iron loss based on the iron loss when W = D = 1.25 mm.

[0115] 17 shows the relationship between the width W of the step portion 12S and the copper loss increase rate. The horizontal axis represents the width W of the step portion 12S, and the vertical axis represents the copper loss increase rate. The copper loss increase rate is a relative value of the copper loss based on the copper loss when W = D = 1.25 mm.

[0116] 18 shows the relationship between the width W of the step portion 12S and the rate of increase in the total loss, which is the sum of iron loss and copper loss. The horizontal axis represents the width W of the step portion 12S, and the vertical axis represents the rate of increase in the total loss. The rate of increase in the total loss is a relative value of the total loss, with the total loss when W = D = 1.25 mm as the reference.

[0117] When the width W of the step portion 12S is reduced, the iron loss increases slightly (see FIG. 16), but the copper loss decreases significantly (see FIG. 17), resulting in a decrease in total loss as shown in FIG. 18. This is because, when the product of the width W and the depth D of the step portion 12S is kept constant, the effect of reducing magnetic saturation by reducing the width W is greater than the effect of reducing the depth D.

[0118] 16 to 18, in order to reduce the total loss, it is desirable that the width W of the step portion 12S is small and the depth D is large. In other words, it is desirable that the width W of the step portion 12S is equal to or smaller than the depth D (i.e., W≦D), and it is more desirable that the width W is smaller than the depth D (i.e., W<D). In other words, it is desirable that the step portion 12S has a shape that is long in the axial direction.

[0119] The desirability of D≧W applies to both the stepped portion 12S of the first and second embodiments. On the other hand, in the second embodiment, the overlap length L0 is longer than in the first embodiment by the amount of protrusion of the thin-walled portion 20T, and the gap length L1 is shorter.

[0120] Therefore, in embodiment 2, the depth D and width W of the step portion 12S are determined so as to reduce iron loss and copper loss, and the protrusion amount of the thin-walled portion 20T can be determined so as to obtain the desired creepage distance and spatial distance.

[0121] 15B, the shortest distance from the contact point P to the step portion 12S is the shorter of the gap length L1 and the width W of the step portion 12S. If the gap length L1 is longer than the width W of the step portion 12S (i.e., L1 > W), the width W of the step portion 12S becomes the shortest distance from the contact point P to the step portion 12S. In this case, the gap length L1 cannot be used as a spatial distance. Therefore, it is desirable that the gap length L1 be equal to or shorter than the width W of the step portion 12S (i.e., L1 ≦ W).

[0122] The width of the thin-walled portion 20T of the insulator 20A is preferably the same as the width W of the step portion 12S. Because the insulator 20A is a resin molded body, if the width of the thin-walled portion 20T is too thin, moldability will decrease, and it will become necessary to increase the pressure applied during injection molding, resulting in increased processing costs.

[0123] When the insulator 20A is made of LCP or PBT, if the width of the thin-walled portion 20T is 0.3 mm or more, sufficient moldability is obtained, and there is no need to increase the pressure applied during injection molding, thereby reducing processing costs.

[0124] As described in the first embodiment, the upper limit of the width W of the step portion 12S is 1.25 mm, so the range of the width W of the step portion 12S can be expressed as 0.3 mm≦W≦1.25 mm.

[0125] Except for the points described above, the stator of embodiment 2 is configured similarly to the stator 1 of embodiment 1. Note that the insulator 20A may have an inclined surface 206 (see FIG. 25 ) instead of the curved surface 203.

[0126] As described above, in the second embodiment, thin-walled portion 20T of insulator 20A protrudes toward step portion 12S beyond end surface 12e of tooth 12, which increases overlap length L0 between insulating film 25 and insulator 20A. This increases the creepage distance, making it easier to ensure an insulation distance between stator core 10 and winding 30.

[0127] Furthermore, by making the width W of the step portion 12S of the tooth 12 equal to or less than the depth D (i.e., W≦D), the occurrence of magnetic saturation within the tooth 12 can be suppressed, and an increase in iron loss and copper loss can be suppressed.

[0128] Furthermore, by making the width W of the step portion 12S of the tooth 12 satisfy 0.3 mm≦W≦1.25 mm, it is possible to suppress the occurrence of magnetic saturation within the tooth 12 without increasing the manufacturing cost.

[0129] Furthermore, since the gap length L1 between the step portion 12S and the insulator 20A is less than or equal to the width W of the step portion 12S (i.e., L1≦W), the gap length L1 can be used as a spatial distance, making it easier to ensure the insulation distance.

[0130] 19 is a cross-sectional view of a tooth 12, an insulator 20, and an insulating film 25 according to a third embodiment, taken along a plane perpendicular to the extension direction of the tooth 12. In the third embodiment, the insulating film 25 is provided so as to fill the space between the stepped portion 12S of the tooth 12 and the insulator 20.

[0131] 20 is a cross-sectional view showing step portion 12S of tooth 12 and the surrounding insulator 20 and insulating film 25. As shown in Fig. 20, insulating film 25 of embodiment 3 has intrusion portion 25b that intrudes into the space between step portion 12S of tooth 12 and insulator 20. The configurations of tooth 12 and insulator 20 are the same as those described in embodiment 1.

[0132] The insertion portion 25b of the insulating film 25 has a first portion B1 in contact with the bottom surface 12b of the step portion 12S, a second portion B2 in contact with the wall surface 12c of the step portion 12S, and a third portion B3 in contact with the opposing surface 204 of the insulator 20. In addition, the aforementioned overlap portion 25a is formed continuously on the tip side of the insertion portion 25b of the insulating film 25.

[0133] In the manufacturing process of the electric motor 3, when electromagnetic steel sheets are laminated to form the stator core 10, a tolerance is set for the axial length of the stator core 10. If the axial length of the stator core 10 falls below the lower limit of the tolerance, it is difficult to adjust the axial length thereafter. Therefore, in practice, the electromagnetic steel sheets are laminated so that the axial length of the stator core 10 approaches the upper limit of the tolerance, and if the upper limit of the tolerance is exceeded, the electromagnetic steel sheets at the axial ends of the stator core 10 are peeled off to bring the axial length of the stator core 10 within the tolerance.

[0134] On the other hand, when the electromagnetic steel sheets at the axial ends of the stator core 10 are peeled off, the depth D of the step portions 12S of the teeth 12 decreases, and the air gap length L1 (FIG. 7) also decreases. As a result, the spatial distance becomes shorter.

[0135] As a redundant design that takes such a situation into consideration, if the creepage distance is increased by the amount that the spatial distance is shortened, it is necessary to further increase the thickness T of the insulator 20. However, increasing the thickness T of the insulator 20 is undesirable because it leads to an increase in the circumferential length of the winding 30.

[0136] 20 , in the third embodiment, the recessed portion 25b of the insulating film 25 enters the space between the step portion 12S of the tooth 12 and the insulator 20. The third portion B3 of the recessed portion 25b contacts the opposing surface 204 of the insulator 20, and the length of this contact portion is the width W of the step portion 12S. This is the length over which the insulators come into contact with each other, and is therefore included in the creepage distance.

[0137] Therefore, the creepage distance in embodiment 3 is the sum of the overlap length L0 described in embodiment 1 and the overlap length (i.e., width W) where the insertion portion 25b of the insulating film 25 overlaps with the insulator 20, i.e., L0 + W.

[0138] Therefore, even if the depth D of the step portion 12S of the tooth 12 and the gap length L1 are reduced during the manufacturing process, the creepage distance can be increased to ensure sufficient insulation between the stator core 10 and the winding 30.

[0139] Except for the points described above, the stator of the third embodiment is configured similarly to the stator 1 of the first embodiment. Note that the insulator 20A of the second embodiment may be provided instead of the insulator 20. Also, an inclined surface may be provided instead of the curved surface 203 of the insulator 20.

[0140] As described above, in embodiment 3, the insulating film 25 has a portion (i.e., the intrusion portion 25b) that intrudes into the space between the step portion 12S of the tooth 12 and the insulator 20, so that sufficient insulation between the stator core 10 and the winding 30 can be ensured regardless of changes in the depth D of the step portion 12S and the gap length L1.

[0141] 21 is a cross-sectional view showing step portion 12S of tooth 12 according to embodiment 4, and the surrounding insulator 20A and insulating film 25. In embodiment 4, insulating film 25 overlaps not only side surface 202 of insulator 20A but also curved surface 203.

[0142] The insulator 20A has a top surface 201 facing axially opposite the end surfaces 12e of the teeth 12, a side surface 202 facing the slots 13, and a curved surface 203 extending from the top surface 201 to the side surface 202. The curved surface 203 is, for example, an arcuate surface.

[0143] The inflection point between the side surface 202 and the curved surface 203 of the insulator 20A is defined as point P1, which serves as a first point. The inflection point between the curved surface 203 and the top surface 201 of the insulator 20A is defined as point P2, which serves as a second point. Points P1 and P2 define both ends of the curved surface 203. The midpoint between points P1 and P2 along the curved surface 203 is defined as midpoint P3.

[0144] The insulator 20A has the thin portion 20T described in the second embodiment. The insulator 20 described in the first embodiment may be used instead of the insulator 20A.

[0145] The insulating film 25 has an overlapping portion 25a that overlaps the side surface 202 of the insulator 20A, and an overlapping portion 25c that overlaps the curved surface 203 of the insulator 20A.

[0146] In Figure 21, the overlap portion 25c of the insulating film 25 is separated from the curved surface 203 of the insulator 20A, but when the winding 30 is wound, the overlap portion 25c curves along the surface of the curved surface 203 of the insulator 20A and comes into contact with the curved surface 203.

[0147] The length L2 of the overlap portion 25c of the insulating film 25 is preferably shorter than half the distance from the first point P1 to the midpoint P2 along the curved surface 203 (i.e., the arc length).

[0148] In other words, it is desirable that the overlapping portion 25c of the insulating film 25 does not extend beyond the midpoint P3 when the overlapping portion 25c is in contact with the curved surface 203. The reason for this will be explained below.

[0149] 22A is a perspective view showing the winding operation of the winding 30 around the insulating films 25 on both sides of the teeth 12. In FIG. 22A, the teeth 12 and the insulators 20A are omitted, and the winding directions of the winding 30 are indicated by arrows W1 to W5.

[0150] 22A , the winding 30 first passes through the slot 13 in the axial direction as shown by arrow W1, and then moves to the adjacent slot 13, straddling the tooth 12 as shown by arrow W2. The winding 30 then passes through the slot 13 in the opposite direction to that of arrow W1 as shown by arrow W3, then returns to the original slot 13, straddling the tooth 12 as shown by arrow W4, and then passes through the slot 13 in the same direction as that of arrow W1 as shown by arrow W5. By repeating this operation, the winding 30 is wound around the tooth 12.

[0151] The insulating film 25 has a first portion 251 that covers the inner circumferential surface 11 a ( FIG. 4 ) of the core back 11 and a second portion 252 that covers the side surface 12 a ( FIG. 21 ) of the tooth 12, and these are integrally formed. During the winding operation of the winding 30 described above, the second portion 252 of the insulating film 25 is pulled toward the center in the width direction of the tooth 12. Because the first portion 251 is formed integrally with the second portion 252, it is also pulled toward the center of the tooth 12.

[0152] Fig. 22(B) is a perspective view showing the shape of the insulating film 25. Although the insulating film 25 is shown in a simplified form in Fig. 22(A) described above, as shown in Fig. 22(B), the insulating film 25 that covers the inner surface of one slot 13 is formed as a single unit. That is, the insulating film 25 has two second portions 252 on either side of a first portion 251 that is bent at the center 250 of the slot 13.

[0153] If excessive pulling force is applied to the two second parts 252 connected by the first part 251, the position of each second part 252 may become misaligned, which may affect the winding condition of the winding 30 or the insulation condition between the stator core 10 and the winding 30.

[0154] Fig. 23 is a schematic diagram for explaining the tension applied to the winding 30 wound around the insulator 20A and the insulating film 25. The insulator 20A in Fig. 23 is the same as that shown in Fig. 15(A) of the second embodiment, and the insulating film 25 is not in contact with the curved surface 203 of the insulator 20A. Both ends of the curved surface 203 of the insulator 20A are defined by points P1 and P2.

[0155] A winding bulge H1 occurs between the winding 30 and the insulating film 25, and a winding bulge H2 occurs between the winding 30 and the top surface 201 of the insulator 20A. When the winding 30 is wound as shown by arrows W1 to W5 in Figure 22A, the winding bulge H2 on the insulator 20A side becomes larger than the winding bulge H1 on the insulating film 25 side. Therefore, the point Pmax at which the tension acting on the winding 30 is maximum is a point Pmax that is displaced toward point P2 from the midpoint P3 between points P1 and P2.

[0156] If the insulating film 25 does not extend to the point Pmax where the tension is maximum, it is possible to avoid excessive tensile force acting on the insulating film 25. Therefore, by preventing the insulating film 25 from extending beyond the midpoint P3 between the points P1 and P2, it is possible to avoid excessive tensile force acting on the insulating film 25.

[0157] Therefore, in embodiment 4, as shown in Figure 21, the length L2 of the overlap portion 25c, which is the protruding length from point P1 of the insulating film 25, is set to be less than 1 / 2 of the length of the curved surface 203 (i.e., the distance from point P1 to point P2 along the curved surface 203).

[0158] This prevents excessive tension from acting on the insulating film 25 during the winding process of the winding 30, and prevents misalignment of the insulating film 25. This improves the winding accuracy of the winding 30 and ensures sufficient insulation between the stator core 10 and the winding 30.

[0159] Note that insulator 20A may have inclined surface 206 (FIG. 25) instead of curved surface 203. In this case, too, the protruding length of insulating film 25 from point P1 is set to be equal to or less than half the length of inclined surface 206 (i.e., the distance between points P1 and P2 along inclined surface 206) and insulating film 25 does not exceed midpoint P3 between points P1 and P2, thereby preventing excessive tensile force from being applied.

[0160] Except for the above-mentioned points, the stator of the fourth embodiment is configured similarly to the stator 1 of the first embodiment. Note that the insulator 20 of the first embodiment may be provided in place of the insulator 20A.

[0161] As described above, in embodiment 4, the insulating film 25 has a portion that overlaps with the curved surface 203 of the insulator 20A (i.e., the overlap portion 25c), thereby further increasing the creepage distance and ensuring insulation between the stator core 10 and the windings 30.

[0162] Furthermore, since the protruding length of insulating film 25 from point P1 is set to 1 / 2 or less of the length of curved surface 203 (i.e., the distance between points P1 and P2 along curved surface 203), excessive tensile force is prevented from acting on insulating film 25 during the winding process of winding 30, and displacement of insulating film 25 can be prevented.

[0163] 24 is a cross-sectional view of a tooth 12, an insulator 20B, and an insulating film 25 according to a fifth embodiment, taken along a plane perpendicular to the extension direction of the tooth 12. In the fifth embodiment, the radius of curvature R of the curved surface 203 of the insulator 20B is equal to or greater than the thickness T of the insulator 20B.

[0164] Similar to insulator 20A of embodiment 2, insulator 20B has thin-walled portion 20T protruding toward step portion 12S. Insulator 20B also has top surface 201 facing away from teeth 12 in the axial direction, side surface 202 facing slot 13, and curved surface 203 extending from top surface 201 to side surface 202. Curved surface 203 is, for example, an arcuate surface.

[0165] The inflection point between the curved surface 203 and the side surface 202 is defined as point P1. The inflection point between the curved surface 203 and the top surface 201 is defined as point P2. Points P1 and P2 define both ends of the curved surface 203. The radius of the arc connecting points P1 and P2 is the radius of curvature R of the curved surface 203.

[0166] The center of curvature C of the curved surface 203 is located within the tooth 12. Therefore, point P1 is located at a position that does not protrude axially beyond the end surface 12e of the tooth 12. Furthermore, the radius of curvature R of the curved surface 203 is equal to or greater than the thickness T of the insulator 20B, and more preferably is greater than the thickness T. In other words, R≧T holds, and more preferably R>T holds.

[0167] As described in the fourth embodiment, insulating film 25 has overlapping portion 25c that overlaps curved surface 203 of insulator 20B. When winding wire 30 is wound, overlapping portion 25c of insulating film 25 curves along curved surface 203 of insulator 20B.

[0168] In this way, the insulation distance can be increased by bringing overlapping portion 25c of insulating film 25 into contact with curved surface 203 of insulator 20B. However, if thickness T of insulator 20B is increased to ensure the length of curved surface 203, the circumferential length of winding 30 will increase.

[0169] Therefore, in the fifth embodiment, point P1, which is the starting position of curved surface 203 of insulator 20B, is positioned opposite wall surface 12c of step portion 12S. This allows thickness T of insulator 20B to be equal to or smaller than radius of curvature R of curved surface 203.

[0170] By reducing the thickness T of insulator 20B, the circumferential length of winding 30 can be shortened, thereby reducing the amount of winding 30 used and copper loss. Furthermore, compared to when the radius of curvature R of curved surface 203 is reduced, the amount of winding 30 that bulges can be reduced, thereby enhancing the effect of reducing the amount of winding 30 used and copper loss.

[0171] Furthermore, since the insulator 20B has the thin portion 20T that protrudes toward the step portion 12S, it is possible to realize a configuration in which the radius of curvature R of the curved surface 203 is equal to or greater than the thickness T of the insulator 20B.

[0172] Except for the points mentioned above, the stator of the fifth embodiment is configured similarly to the stator 1 of the first embodiment. Note that the insulating film 25 may be disposed as described in the third embodiment.

[0173] As described above, in embodiment 5, the radius of curvature R of curved surface 203 of insulator 20B and the thickness T of insulator 20B satisfy R≧T, and therefore the thickness T of insulator 20B can be made thinner to shorten the circumferential length of winding 30, thereby reducing copper loss.

[0174] Note that, as the radius of curvature R of curved surface 203 of insulator 20B increases, there is an advantage in that the amount of resin material used to form insulator 20B decreases, but if the radius of curvature R is too large, it becomes difficult to wind winding 30. Therefore, it is desirable that the radius of curvature R of curved surface 203 of insulator 20B be 3 mm or less. In other words, it is desirable that R≦3 mm be satisfied.

[0175] The range of the radius of curvature R of the curved surface 203 (R≦3 mm) is not limited to the fifth embodiment, but can also be applied to the insulators of the first to fourth embodiments and the sixth to tenth embodiments described later.

[0176] 25 is a cross-sectional view taken along a plane perpendicular to the extension direction of the teeth 12, showing the teeth 12, insulator 20C, and insulating film 25 of a modification of embodiment 5. In embodiment 5, insulator 20C has an inclined surface 206 instead of curved surface 203 (FIG. 24).

[0177] As shown in FIG. 25 , the insulator 20C has a top surface 201 facing axially opposite the end surface 12e of the tooth 12, a side surface 202 facing the slot 13, and an inclined surface 206 extending from the top surface 201 to the side surface 202.

[0178] The inflection point between the inclined surface 206 and the side surface 202 is defined as point P1. The inflection point between the inclined surface 206 and the top surface 201 is defined as point P2. The points P1 and P2 define both ends of the inclined surface 206.

[0179] The distance between points P1 and P2 in the tooth width direction is defined as distance E1. The distance between points P1 and P2 in the axial direction is defined as distance E2. At least one of distances E1 and E2 is equal to or greater than the thickness T of insulator 20C. That is, at least one of E1≧T and E2≧T holds true.

[0180] The intersection of a line in the tooth width direction passing through point P1 and a line in the axial direction passing through point P2 is defined as point E. Point E is located within tooth 12. The above-mentioned distance E1 is the distance from point E to point P1, and the above-mentioned distance E2 is the distance from point E to point P2. Insulator 20C has a thin-walled portion 20T that protrudes toward step portion 12S.

[0181] The insulating film 25 has an overlapping portion 25c that overlaps the inclined surface 206 of the insulator 20C. When the winding 30 is wound, the overlapping portion 25c of the insulating film 25 is inclined along the inclined surface 206 of the insulator 20C.

[0182] In this modification, point P1, which is the starting position of inclined surface 206 of insulator 20C, is located at a position that does not protrude in the axial direction beyond end surfaces 12e of teeth 12. This satisfies at least one of E1 ≥ T and E2 ≥ T, and more preferably both.

[0183] In this modification, by reducing the thickness T of the insulator 20C, it is possible to reduce the amount of winding 30 used and copper loss, as in embodiment 5. Furthermore, since it is possible to reduce the swelling of the winding 30, it is possible to further shorten the circumferential length of the winding 30, thereby enhancing the effect of reducing the amount of winding 30 used and copper loss.

[0184] The longer the length of the inclined surface 206 of the insulator 20C, the less resin material is required to form the insulator 20C. However, if the length of the inclined surface 206 is too long, it becomes difficult to wind the winding 30. Therefore, the length of the inclined surface 206 of the insulator 20C, i.e., √(E1 ２ +E2 ２ ) is preferably 3 mm or less. ２ +E2 ２ )≦3 mm.

[0185] The desired range of the length of the inclined surface 206 (√(E1 ２ +E2 ２ )≦3 mm) is not limited to the modified example of embodiment 5, but can also be applied to insulators of embodiments 1 to 4 and embodiments 6 to 10 described below when the curved surface 203 is changed to an inclined surface.

[0186] 26 is a cross-sectional view taken along a plane perpendicular to the extension direction of the teeth 12, showing the teeth 12, insulators 20A, and insulating films 25 of a stator 1 according to a sixth embodiment. In the sixth embodiment, of the step portions 12S at both axial ends of the teeth 12, the depth D1 of the step portion 12S located on a first axial side is greater than the depth D2 of the step portion 12S located on a second axial side (i.e., D1 > D2).

[0187] In Fig. 26, the upper side is the +Z direction and the lower side is the -Z direction. The upper side (+Z direction) shown in Fig. 26 is the side where winding of the winding 30 starts, i.e., the first side, and the lower side (-Z direction) is the opposite side, i.e., the second side.

[0188] The side where winding of winding 30 starts is the side of the starting point of arrow W1 shown in Figure 22(A), i.e., the upper side in Figure 22(A). The upper step 12S is also referred to as the first step, and the lower step 12S is also referred to as the second step. Note that the upper side (+Z direction) and the lower side (-Z direction) do not necessarily coincide with the upper side and the lower side when motor 3 is in use.

[0189] In the teeth 12, the upper step portion 12S has a depth D1 in the axial direction and a width W in the tooth width direction. The lower step portion 12S has a depth D2 in the axial direction and a width W in the tooth width direction. The depths D1 and D2 of the upper and lower step portions 12S satisfy the relationship D1 > D2. Meanwhile, the widths W of the upper and lower step portions 12S are the same.

[0190] The axial length of the gap between the upper step portion 12S and the insulator 20A is defined as gap length L11, and the axial length of the gap between the lower step portion 12S and the insulator 20A is defined as gap length L12.

[0191] The insulators 20A provided on both axial ends of the tooth 12 have the same shape and dimensions. The insulators 20A have the thin-walled portions 20T described in the second embodiment.

[0192] Since the depths D1 and D2 of the upper and lower step portions 12S satisfy D1>D2, the gap lengths L11 and L12 satisfy L11>L12.

[0193] The insulating film 25 is fixed to the stator core 10 by winding the windings 30 around it, rather than by adhesive. However, there is a tolerance in the axial length of the insulating film 25, and there is also a tolerance in the axial length of the stator core 10. In general, the tolerance of the stator core 10 is larger than the tolerance of the insulating film 25.

[0194] Therefore, when insulating film 25 is fixed to stator core 10 by winding windings 30, gravity displaces insulating film 25 downward relative to stator core 10. When insulating film 25 displaces downward, upper overlap length L0 becomes shorter and lower overlap length L0 becomes longer.

[0195] In the sixth embodiment, as described above, the depth D1 of the upper step 12S is greater than the depth D2 of the lower step 12S, and therefore the upper air gap length L11 is greater than the lower air gap length L12. Therefore, even if the upper overlap length L0 is shortened, the spatial distance at the upper step 12S can be increased, and sufficient insulation between the stator core 10 and the winding 30 can be ensured.

[0196] Here, the insulator 20A is formed using a forming die, and the insulating film 25 is cut out from a roll of material, so the axial length of both has little variation. In contrast, the stator core 10 is assembled by stacking electromagnetic steel sheets in the axial direction, so the axial length has large variation.

[0197] The sheet thickness of the electromagnetic steel sheets constituting the stator core 10 is Ts (mm), the number of laminated sheets is Ns, and the space factor is Fs. The space factor Fs is the ratio of the product of the sheet thickness Ts and the number of laminated sheets Ns to the axial length Ls (mm) of the stator core 10, and is expressed as Fs = (Ts × Ns) / Ls.

[0198] When assembling stator core 10, the number Ns of laminated electromagnetic steel sheets is determined based on the target value of the axial length of stator core 10 and the sheet thickness Ts of the electromagnetic steel sheets, but variations in space factor Fs also cause variations in the axial length of stator core 10. The downward displacement of insulating film 25 described above occurs by an amount corresponding to the variation in the axial length of stator core 10.

[0199] The variation V in the axial length of the stator core 10 is expressed as V=Ts×Ns×(1−Fs) using the plate thickness Ts, the number of laminated sheets Ns, and the space factor Fs. It is desirable that the difference (D1−D2) between the depths D1 and D2 satisfies D1−D2<Ts×Ns×(1−Fs).

[0200] In this way, at least a portion of the reduction in overlap length L0 on the first side (e.g., the upper side) due to displacement of the insulating film 25 can be compensated for by the difference between the depths D1 and D2, thereby ensuring sufficient insulation between the stator core 10 and the windings 30.

[0201] Except for the points described above, the stator of the sixth embodiment is configured similarly to the stator 1 of the first embodiment. Note that the insulator 20 of the first embodiment, the insulator 20B of the fifth embodiment, or the insulator 20C of the modified example may be provided instead of the insulator 20A. Also, an inclined surface may be provided instead of the curved surface 203 of the insulator 20.

[0202] As described above, in embodiment 6, the depth D1 of the step portion 12S on the first axial side (e.g., the upper side) and the depth D2 of the step portion 12S on the second axial side (e.g., the lower side) satisfy D1 > D2, so that the reduction in the overlap length L0 on the first side caused by the displacement of the insulating film 25 to the second side can be compensated for by the difference between the depths D1 and D2.

[0203] Furthermore, by making the depths D1 and D2 of the step portions 12S on the first and second sides satisfy D1-D2<Ts×Ns×(1-Fs), the reduction in creepage distance on the first side due to displacement of the insulating film 25 caused by variations in the axial length of the stator core 10 can be compensated for by the difference in depths D1 and D2.

[0204] 27 is a cross-sectional view showing a step portion 12S of a tooth 12F of a stator 1 according to a seventh embodiment, and the surrounding insulator 20 and insulating film 25. The tooth 12F of the seventh embodiment has an intermediate step portion 12d in the step portion 12S.

[0205] 27, the intermediate step portion 12d is provided so as to protrude in the axial direction from the bottom surface 12b of the stepped portion 12S and protrude from the wall surface 12c toward the slot 13. The intermediate step portion 12d is formed of an electromagnetic steel plate.

[0206] The intermediate step portions 12 d are formed by gradually changing the width of the electromagnetic steel sheets that make up the teeth 12 F. By forming the intermediate step portions 12 d, the width of the teeth 12 F can be increased, which reduces the magnetic resistance of the teeth 12 F and suppresses the occurrence of magnetic saturation.

[0207] The step portion 12S has a depth D in the axial direction and a width W in the tooth width direction. A gap is provided between the bottom surface 12b of the step portion 12S and the insulator 20, and has a gap length L1.

[0208] The insulator 20 has the same configuration as the insulator 20 (FIG. 7) of embodiment 1. The intersection of the opposing surface 204 of the insulator 20 facing the step portion 12S and the surface of the insulating film 25 on the tooth 12F side is defined as point P.

[0209] As described in embodiment 1, the spatial distance is determined by the shorter of the distance from point P to the bottom surface 12b of the step portion 12S (i.e., the width W) and the distance from point P to the wall surface 12c (i.e., the gap length L1).

[0210] If the smaller of the width W of the step portion 12S and the gap length L1 is represented by Q, the intermediate step portion 12d is preferably formed outside a circle (also referred to as a reference circle) having a radius Q and centered at point P. In this way, the intermediate step portion 12d can be formed without affecting the spatial distance.

[0211] Fig. 28 is a cross-sectional view showing another example of the configuration of the step portion 12S of the tooth 12F according to embodiment 7. As shown in Fig. 28, the step portion 12S of the tooth 12F may be provided with an intermediate step portion 12d having a plurality of steps.

[0212] By providing intermediate step portions 12d having multiple steps (steps d1 to d4 in FIG. 28) in step portion 12S, the width of teeth 12F can be further increased, thereby enhancing the effect of reducing magnetic resistance and suppressing magnetic saturation in teeth 12F. The number of steps in intermediate step portion 12d is four here, but it may be less than four or five or more.

[0213] 27 and 28 show an example in which the depth D, width W, and gap length L1 of the step portion 12S are the same, but one of the depth D, width W, and length L1 may be different from the others, or all three may be different.

[0214] Except for the points mentioned above, the stator of the seventh embodiment is configured similarly to the stator 1 of the first embodiment. Insulator 20 may be replaced with insulator 20A of the second embodiment, insulator 20B of the fifth embodiment, or insulator 20C of a modified example. In addition, insulating film 25 may be disposed as described in the third and fourth embodiments. In addition, an inclined surface may be provided instead of curved surface 203 of insulator 20.

[0215] As described above, in embodiment 7, intermediate step portion 12d is formed in step portion 12S of tooth 12F, which reduces the magnetic resistance in tooth 12F and suppresses the occurrence of magnetic saturation, thereby suppressing an increase in iron loss and copper loss.

[0216] Furthermore, if the smaller of the width W of the step portion 12S and the gap length L1 is defined as Q, the intermediate step portion 12d is formed outside the circle of radius Q centered at point P, and therefore the intermediate step portion 12d can be formed without affecting the spatial distance.

[0217] 29 is a cross-sectional view taken along a plane perpendicular to the extension direction of the teeth 12, showing the teeth 12, insulator 40, and insulating film 26 of a stator 1 according to an eighth embodiment. In the eighth embodiment, the insulator 40 has a recess 41 into which a portion of the insulating film 26 is inserted.

[0218] 29, the insulator 40 has a recess 41 on the side facing the end face 12e of the tooth 12. The recess 41 of the insulator 40 faces a part of the step portion 12S of the tooth 12 in the axial direction.

[0219] 30 is a cross-sectional view showing step portion 12S of tooth 12 and the surrounding insulator 40 and insulating film 25. Recess 41 of insulator 40 has recess bottom surface 41b facing end surface 12e of tooth 12, recess inner surface 41a located on the slot 13 side of recess bottom surface 41b, and recess inner surface 41c facing recess inner surface 41a.

[0220] The recess inner surface 41a is located at a position that protrudes further toward the slot 13 than the wall surface 12c of the step portion 12S in the tooth width direction. On the other hand, the recess inner surface 41c is located on the end surface 12e of the tooth 12.

[0221] The insulator 40 also has a top surface 401 facing axially in the opposite direction to the end surfaces 12 e of the teeth 12, a side surface 402 facing the slots 13, and a curved surface 403 extending from the top surface 401 to the side surface 402. The top surface 401 is also referred to as a first surface, the side surface 402 is also referred to as a second surface, and the curved surface 403 is also referred to as a third surface.

[0222] The axial depth Lc of the recess 41 of the insulator 40 is the distance from the end face 12e of the tooth 12 to the recess bottom surface 41b. The distance from the side surface 402 of the insulator 40 to the recess 41 is defined as La. The portion of the bottom surface of the insulator 40 located between the side surface 402 of the insulator 40 and the recess inner surface 41a of the recess 41 is defined as the opposing surface 405. The opposing surface 405 of the insulator 40 faces the step portion 12S of the tooth 12. The length of the opposing surface 405 in the tooth width direction is the above-mentioned distance La.

[0223] The insulating film 26 is provided to cover the side surface 12a of the tooth 12. The insulating film 26 further has an insertion portion 26a that is inserted into the recess 41 via the step portion 12S of the tooth 12. The insertion portion 26a is inclined with respect to the axial direction and extends linearly.

[0224] The insulation distance between the stator core 10 and the winding 30 is the sum of the distance La from the side surface 402 of the insulator 40 to the recess 41, the length Lb of the portion of the insertion portion 26a located within the recess 41, and the axial depth Lc of the recess 41.

[0225] In this way, the insertion portion 26a of the insulating film 26 is inserted into the recess 41 of the insulator 40 through the step portion 12S of the tooth 12, so that the insulation distance is ensured by the above La + Lb + Lc, and insulation between the stator core 10 and the winding 30 can be ensured.

[0226] Furthermore, since the recess 41 is formed inside the insulator 40, the size and shape of the recess 41 do not affect the winding state of the winding 30, and therefore the insulation distance can be easily adjusted.

[0227] The insulator 40 has the same structure as the insulator 20 of the first embodiment, except that it has a recess 41. The insulating film 26 has the same structure as the insulating film 25 of the first embodiment, except that it has an insertion portion 26a.

[0228] Except for the points described above, the stator of embodiment 8 is configured similarly to the stator 1 of embodiment 1. Note that the insulator 40 may be provided with the thin-walled portion 20T described in embodiment 2. Also, instead of the curved surface 403 of the insulator 40, an inclined surface may be provided.

[0229] As described above, in the eighth embodiment, the insulator 40 has the recess 41 that faces at least a part of the step portion 12S of the tooth 12 in the axial direction, and the insertion portion 26a of the insulating film 26 is inserted into the recess 41 via the step portion 12S. Therefore, the insulation distance can be increased by the distance La from the side surface 402 of the insulator 40 to the recess 41 and the length Lb of the insertion portion 26a within the recess 41, etc. This ensures sufficient insulation between the stator core 10 and the winding 30.

[0230] 31 is a cross-sectional view of a stator 1 according to a ninth embodiment, taken along a plane perpendicular to the direction in which the teeth 12 extend, showing the teeth 12, insulator 40A, and insulating film 27. In the ninth embodiment, thin-walled portion 40T formed on insulator 40A is configured to guide a portion of insulating film 27.

[0231] 31, the insulator 40A has a recess 41 on the side facing the end face 12e of the tooth 12. The recess 41 of the insulator 40A faces a part of the step portion 12S of the tooth 12 in the axial direction.

[0232] 32 is a cross-sectional view showing step portion 12S of tooth 12 and the surrounding insulator 40A and insulating film 27. Recess 41 of insulator 40A has recess inner surface 41a, recess bottom surface 41b, and recess inner surface 41c, similar to recess 41 of insulator 40 of embodiment 8 (FIG. 30). Axial depth Lf of recess 41 is the distance from end surface 12e of tooth 12 to recess bottom surface 41b.

[0233] The portion of the insulator 40A between the recess 41 and the side surface 402 is referred to as a thin portion 40T. The thin portion 40T has a width Ld in the tooth width direction. The thin portion 40T is also referred to as a guide portion.

[0234] A part of the thin portion 40T faces the wall surface 12c of the step portion 12S. A gap into which the insulating film 27 can be inserted is formed between the thin portion 40T and the wall surface 12c of the step portion 12S.

[0235] The insulating film 27 is provided to cover the side surface 12a of the tooth 12. The insulating film 27 further has an insertion portion 27a that passes through the step portion 12S of the tooth 12 and is inserted into the recess 41 of the insulator 40A.

[0236] The insertion portion 27a of the insulating film 27 is guided by the thin portion 40T of the insulator 40A and the wall surface 12c of the stepped portion 12S and extends in the axial direction. The portion of the insertion portion 27a that extends in the axial direction while being guided by the thin portion 40T, etc., is referred to as a first portion S1.

[0237] The portion of the insertion portion 27a of the insulator 40A that does not reach the thin-walled portion 40T extends at an angle relative to the axial direction. The portion of the insertion portion 27a that extends at an angle is referred to as a second portion S2. That is, the insertion portion 27a of the insulator 40A has a bent shape.

[0238] The insulation distance between the stator core 10 and the winding 30 is the sum of the width Ld of the thin-walled portion 40T of the insulator 40A, the length Le of the first part S1 of the insertion portion 27a of the insulating film 27, and the axial depth Lf of the recess 41.

[0239] Insulator 40A has the same structure as insulator 20 of embodiment 1, except that it has recess 41 and thin-walled portion 40T. Insulating film 27 has the same structure as insulating film 25 of embodiment 1, except that it has insertion portion 27a.

[0240] The insulating film 27 is made of a resin such as PET and has sufficient strength to ensure reliability. Therefore, a processing step is required to bend the insulating film 27 at a desired angle.

[0241] In the ninth embodiment, the insertion portion 27a of the insulating film 27 is guided by the thin portion 40T of the insulator 40A and inserted into the recess 41, so that the inclination angle of the insertion portion 27a is smaller than the inclination angle of the insertion portion 26a in the eighth embodiment. This reduces the amount of bending of the insulating film 27. Furthermore, the insertion operation of the insulating film 27 can be simplified.

[0242] Except for the points described above, the stator of embodiment 9 is configured similarly to the stator 1 of embodiment 1. Note that thin-walled portion 40T of insulator 40A does not have to protrude toward step portion 12S. Also, an inclined surface may be provided instead of curved surface 403 of insulator 40A.

[0243] As described above, in the ninth embodiment, insulator 40A has recess 41 facing a part of step portion 12S of tooth 12, has thin-walled portion 40T on the slot 13 side of recess 41, and insertion portion 27a of insulating film 27 is guided by thin-walled portion 40T and inserted into recess 41. Therefore, sufficient insulation between stator core 10 and winding 30 can be ensured while keeping the amount of bending of insulating film 27 small.

[0244] 33 is a cross-sectional view showing a step portion 12S of a tooth 12 in a stator 1 according to a tenth embodiment, and the surrounding insulator 40B and insulating film 26. In the tenth embodiment, a thin portion 40T of the insulator 40B has an inclination.

[0245] 33, the insulator 40B has a recess 42 on the side facing the end face 12e of the tooth 12. The recess 42 of the insulator 40B faces a part of the step portion 12S of the tooth 12 in the axial direction.

[0246] The recess 42 of the insulator 40B has a recess inner surface 42a, a recess bottom surface 42b, and a recess inner surface 42c, similar to the recess 41 (FIG. 32) of the insulator 40A of the ninth embodiment.

[0247] The portion of the insulator 40B between the recess 42 and the side surface 402 is referred to as a thin portion 40T. The tip of the thin portion 40T on the step portion 12S side is referred to as a tip portion U.

[0248] The thin portion 40T of the insulator 40B faces the wall surface 12c of the step portion 12S of the tooth 12. A gap into which the insulating film 26 can be inserted is formed between the thin portion 40T and the wall surface 12c of the step portion 12S.

[0249] The inner surface of the thin portion 40T is the inner surface 42a of the recess 42. The width of the thin portion 40T is determined by the distance between the side surface 402 of the insulator 40B and the inner surface 42a of the recess. The inner surface 42a of the recess is inclined so that the width of the thin portion 40T becomes narrower as it approaches the tip U.

[0250] The insulating film 26 is provided to cover the side surface 12a of the tooth 12. The insulating film 26 further has an insertion portion 26a that is inserted into the recess 42 via the step portion 12S of the tooth 12. The insertion portion 26a is inserted into the recess 42 while being guided along the inner surface of the thin-walled portion 40T of the insulator 40B (i.e., the inner surface 42a of the recess).

[0251] Insulator 40B has the same configuration as insulator 20 of embodiment 1, except that it has recess 42 and thin-walled portion 40T. Insulating film 26 has the same configuration as insulating film 25 of embodiment 1, except that it has insertion portion 26a.

[0252] When the insulator 40B is formed by resin injection molding, the thin-walled portion 40T corresponds to the portion of the mold into which the resin is finally filled. As described above, the thin-walled portion 40T has a shape that narrows toward the tip end U, thereby improving moldability. Furthermore, the insulating film 26 can be easily inserted into the recess 24, simplifying the manufacturing process.

[0253] Except for the above-mentioned points, the stator of the tenth embodiment is configured similarly to the stator 1 of the first embodiment. Note that instead of the curved surface 403 of the insulator 40B, an inclined surface may be provided.

[0254] As described above, in the tenth embodiment, the insulator 40B has the recess 41 facing at least a part of the step 12S of the tooth 12, and has the thin-walled portion 40T on the slot 13 side of the recess 41, and the thin-walled portion 40T has a slope that decreases in width toward the tip end U. This improves the formability of the insulator 40B and makes it easier to insert the insulating film 26.

[0255] Fig. 34 is a cross-sectional view showing another configuration example of the insulator 40B according to embodiment 10. In the configuration example shown in Fig. 34, the insulator 40B protrudes from the side surface 12a of the tooth 12 toward the slot 13 side.

[0256] 34 , in the tenth embodiment, the side surface 402 of the insulator 40B protrudes from the side surface 12 a of the tooth 12 toward the slot 13 (the right side in FIG. 34 ). The amount of protrusion of the side surface 402 of the insulator 40B from the side surface 12 a of the tooth 12 toward the slot 13 is referred to as protrusion amount G.

[0257] The insulating film 26 is inserted into the recess 42 on the inside of the insulator 40B, and is not disposed on the outside of the insulator 40B. Therefore, if the insulator 40B is made to protrude toward the slot 13 beyond the side surface 12a of the tooth 12 and the protrusion amount G is made close to the thickness F of the insulating film 26, the winding 30 can be performed smoothly.

[0258] The thickness F of the insulating film 26 is 0.1 mm to 0.3 mm. Therefore, it is desirable that the protrusion amount G of the insulator 40B from the side surface 12a of the tooth 12 satisfies 0.1 mm≦G≦0.3 mm.

[0259] 35 is a cross-sectional view showing another example of the configuration of insulator 40B according to embodiment 10. In the example of the configuration shown in Fig. 35, the amount of protrusion from side surface 12a of tooth 12 of insulator 40B exceeds thickness F of insulating film 26.

[0260] As explained in the first embodiment, a winding bulge H1 occurs between the winding 30 and the insulating film 26. Therefore, if the amount of protrusion G of the insulator 40B from the side surface 12a of the tooth 12 is made closer to the sum of the thickness F of the insulating film 26 and the amount of winding bulge, the winding of the winding bulge will be smoother.

[0261] The thickness F of the insulating film 26 is 0.1 mm to 0.3 mm, and the amount of swelling is generally 0.2 mm. Therefore, it is desirable that the amount of protrusion G of the insulator 40B from the side surface 12a of the tooth 12 satisfies 0.3 mm≦G≦0.5 mm.

[0262] The configuration examples of FIGS. 34 and 35 are based on the configuration of the eighth embodiment (FIGS. 29 and 30), but are also applicable to the ninth and tenth embodiments.

[0263] The features described in the first to tenth embodiments and the modifications can be combined. For example, the configuration in which the depth D of the step portion 12S is different at both axial ends of the tooth 12 as in the sixth embodiment can also be applied to the first to fifth and seventh to tenth embodiments.

[0264] <Compressor> Next, a compressor 8 to which the electric motors of the first to tenth embodiments and the modified examples can be applied will be described. Fig. 36 is a cross-sectional view showing the configuration of compressor 8. Compressor 8 is a rotary compressor in this case, and has a sealed container 80, a compression mechanism 9 disposed within the sealed container 80, an electric motor 3 that drives the compression mechanism 9, and a shaft 90 that connects the electric motor 3 and the compression mechanism 9 so as to be capable of transmitting power. Shaft 90 is the shaft 90 shown in Fig. 1 and other figures, and is fitted into the central hole 53 (Fig. 1) of the rotor 5 of electric motor 3.

[0265] The sealed container 80 is a sealed container made of, for example, a steel plate, and covers the electric motor 3 and the compression mechanism 9. The sealed container 80 has an upper frame 82 and a lower frame 81. Attached to the upper frame 82 are a glass terminal 83 serving as a terminal for supplying power to the electric motor 3, and a discharge pipe 85 for discharging the refrigerant compressed in the compressor 8 to the outside. The electric motor 3 and the compression mechanism 9 are housed in the frame 81.

[0266] 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 inside of the frame 81. 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.

[0267] 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.

[0268] 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.

[0269] Refrigerating machine oil (not shown) for lubricating each sliding part of the compression mechanism 9 is stored in the bottom of the frame 81 of the sealed container 80. The refrigerating machine oil flows up 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.

[0270] The stator 1 of the electric motor 3 is attached to the inside of a frame 81 by shrink fitting. Electric power is supplied to the windings 30 of the stator 1 from glass terminals 83 attached to an upper frame 82. A shaft 90 is fixed in the central hole 53 of the rotor 5 (FIG. 1).

[0271] An accumulator 87 that stores refrigerant gas is attached to the frame 81. The accumulator 87 is held by, for example, a holder 86 provided on the outside of the frame 81. A pair of suction pipes 88, 89 are attached to the frame 81, and refrigerant gas is supplied from the accumulator 87 to cylinders 91, 92 via the suction pipes 88, 89.

[0272] 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.

[0273] (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.

[0274] 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 3 is driven and rotor 5 rotates, 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 groove 18 of stator 1 (FIG. 1) and through holes 57 and 58 of rotor 5 (FIG. 2), rises within sealed container 80, and is discharged to the outside through discharge pipe 85.

[0275] The compressor in which the electric motor 3 is used is not limited to a rotary compressor, but may be, for example, a scroll compressor.

[0276] The electric motor 3 including the stator described in each embodiment and modification has high motor efficiency due to reduced iron loss and copper loss in the teeth 12. As a result, the operating efficiency of the compressor 8 can be improved.

[0277] <Refrigeration cycle device> Next, a refrigeration cycle device 300 having the compressor 8 shown in Fig. 36 will be described. Fig. 37 is a diagram showing the refrigeration cycle device 300. The refrigeration cycle device 300 is, for example, an air conditioner, but is not limited to this and may be, for example, a refrigerator.

[0278] 37 includes a compressor 301, a condenser 302 that condenses a refrigerant, a pressure reducing device 303 that reduces the pressure of the refrigerant, and an evaporator 304 that evaporates the refrigerant. The compressor 301, the condenser 302, and the pressure reducing device 303 are provided in an outdoor unit 310, and the evaporator 304 is provided in an indoor unit 320.

[0279] The compressor 301, the condenser 302, the pressure reducing device 303, and the evaporator 304 are connected by refrigerant piping 307 to form a refrigerant circuit. The compressor 301 is configured as the compressor 8 shown in Figure 36. The refrigeration cycle device 300 also includes an outdoor fan 305 facing the condenser 302 and an indoor fan 306 facing the evaporator 304.

[0280] The refrigeration cycle apparatus 300 operates as follows: The compressor 301 compresses the refrigerant it draws in and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 302 exchanges heat between the refrigerant sent out from the compressor 301 and outdoor air sent by the outdoor air blower 305, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 303 expands the liquid refrigerant sent out from the condenser 302 and sends it out as low-temperature, low-pressure liquid refrigerant.

[0281] The evaporator 304 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 303 and the indoor air, evaporating the refrigerant and sending it out as refrigerant gas. The air from which heat has been removed by the evaporator 304 is supplied into the room by the indoor fan 306.

[0282] Since the compressor 301 of the refrigeration cycle device 300 can be applied with an electric motor 3 equipped with the stator 1 described in each embodiment and variant example, the operating efficiency and reliability of the refrigeration cycle device 300 can be improved.

[0283] 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.

[0284] DESCRIPTION OF SYMBOLS 1 stator, 3 electric motor, 5 rotor, 8 compressor, 9 compression mechanism, 10 stator core, 11 core back, 12 teeth, 12S step portion, 12a side surface, 12b bottom surface, 12c wall surface, 12d intermediate step portion, 12e end surface, 13 slot, 14 divided core, 20 insulator, 20T thin portion, 25 insulating film, 25a overlap portion, 25b insertion portion, 25c overlap portion, 26, 27 insulating film, 26a, 27a insertion portion, 30 winding, 40, 40A, 40B insulator, 40T thin portion, 41, 42 recess, 50 rotor core, 51 magnet insertion hole, 55 Permanent magnet, 80: sealed container, frame, 201: top surface (first surface), 202: side surface (second surface), 203: curved surface (third surface), 204, 205: opposing surface, 206: inclined surface (third surface), 301: compressor, 302: condenser, 303: pressure reducing device, 304: evaporator, 401: top surface (first surface), 402: side surface (second surface), 403: curved surface (third surface), 405: opposing surface, D: depth of stepped portion, L1: gap length, P: contact, W: width of stepped portion.

Claims

1. A stator core having an annular core back, teeth extending radially inward from the core back, and slots circumferentially adjacent to the teeth, An insulating portion provided on the teeth, The windings wound around the teeth via the aforementioned insulating portion Equipped with, The teeth have an end face facing the axial direction of the stator core, a side surface facing the slot, and a stepped portion formed between the end face and the side surface. The insulating portion comprises an insulator that covers the end face of the teeth and an insulating film that covers the side surface of the teeth and a part of the insulator. If the direction perpendicular to both the extending direction and the axial direction of the teeth is defined as the tooth width direction, then the stepped portion has a depth D in the axial direction and a width W in the tooth width direction. A gap is provided in the axial direction between the stepped portion of the teeth and the insulator. The sum of the shortest distance from the contact point between the surface of the insulator facing the stepped portion and the insulating film to the stepped portion, and the overlap length L0, which is the length of overlap between the insulating film and the insulator, is greater than or equal to the insulation distance required for insulation between the stator core and the winding. At least one of the following conditions holds: 0 < D ≤ 1.25 mm and 0 < W ≤ 1.25 mm. stata.

2. The void length L1, which is the axial length of the void, satisfies 0 < L1 ≤ D. The stator according to claim 1.

3. The gap length L1, which is the axial length of the gap, and the width W of the stepped portion satisfy L1 ≤ W. The stator according to claim 1 or 2.

4. The insulator has a thin-walled portion that protrudes from the end face of the teeth toward the stepped portion, The insulating film also overlaps with the thin portion. The stator according to claim 1 or 2.

5. The depth D and width W of the stepped portion satisfy W ≤ D. The stator according to claim 1 or 2.

6. The width W of the stepped portion satisfies the condition 0.3 mm ≤ W ≤ 1.25 mm. The stator according to claim 1 or 2.

7. A portion of the insulating film is inserted into the stepped portion of the teeth. The stator according to claim 1 or 2.

8. The insulator has a first surface facing the end face of the teeth, a second surface facing the slot, and a third surface which is a curved or inclined surface extending between the first and second surfaces. The stator according to claim 1 or 2.

9. Let P1 be the boundary between the third surface and the second surface, and let P2 be the boundary between the third surface and the first surface. The length L2 of the portion of the insulating film that protrudes beyond point P1 is less than or equal to half the distance from point P1 to point P2 along the third surface. The stator according to claim 8.

10. The third surface of the insulator is a curved surface, Let T be the distance between the first surface of the insulator and the end surface of the teeth. If the radius of curvature of the curved surface is R, R ≥ T holds true. The stator according to claim 8.

11. The third surface of the insulator is an inclined surface, Let T be the distance between the first surface of the insulator and the end surface of the teeth. Let P1 be the inflection point between the third surface and the second surface, and let P2 be the inflection point between the third surface and the first surface. Let E1 be the distance between point P1 and point P2 in the tooth width direction. If E2 is the distance between point P1 and point P2 in the axial direction, At least one of T ≤ E1 and T ≤ E2 holds. The stator according to claim 8.

12. The third surface of the insulator is a curved surface, The radius of curvature R of the curved surface satisfies R ≤ 3 mm. The stator according to claim 8.

13. The third surface of the insulator is an inclined surface, Let P1 be the inflection point between the third surface and the second surface, and let P2 be the inflection point between the third surface and the first surface. The distance E1 between point P1 and point P2 in the tooth width direction is defined as follows: If E2 is the distance between point P1 and point P2 in the axial direction, √(E1) ２ +E2 ２ ) ≤ 3 mm holds true The stator according to claim 8.

14. If the thermal expansion coefficient of the insulating film is α, the axial length of the insulating film at 20°C is Li, and the upper limit temperature of the allowable temperature range of the stator is Tmax, then The width W of the stepped portion satisfies W ≥ Li × α × (Tmax - 20) / 2. The stator according to claim 1 or 2.

15. The teeth have a first stepped portion on the first axial side, The teeth have a second stepped portion on the second axial side, The axial depth D1 of the first stepped portion and the axial depth D2 of the second stepped portion satisfy D1 > D2. The stator according to claim 1 or 2.

16. If the thickness of the electrical steel sheet constituting the stator core is Ts, the number of layers of the electrical steel sheet is Ns, and the space factor is Fs, then D1-D2<Ts×Ns×(1-Fs) The following holds true. The stator according to claim 15.

17. The teeth have an intermediate step portion in the stepped portion, If we define a reference circle as having a radius equal to the shorter of the gap length L1, which is the axial length of the gap, and the width W of the step, with respect to the contact point between the surface of the insulator facing the stepped portion and the insulating film, then The aforementioned intermediate step is located outside the reference circle. The stator according to claim 1 or 2.

18. The insulator protrudes more towards the slot than the side surface of the teeth. The stator according to claim 1 or 2.

19. The amount G of the insulator protruding from the side surface of the teeth satisfies the condition 0.1 mm ≤ G ≤ 0.3 mm. The stator according to claim 18.

20. The amount G of the insulator protruding from the side surface of the teeth satisfies the condition 0.3 mm ≤ G ≤ 0.5 mm. The stator according to claim 18.

21. A stator core having an annular core back, teeth extending radially inward from the core back, and slots circumferentially adjacent to the teeth, An insulating portion provided on the teeth, The windings wound around the teeth via the aforementioned insulating portion Equipped with, The teeth have an end face facing the axial direction of the stator core, a side surface facing the slot, and a stepped portion formed between the end face and the side surface. The insulating portion comprises an insulator covering the end face of the teeth and an insulating film covering the side surface of the teeth. The insulator has a recess that faces at least a portion of the stepped portion of the teeth, A portion of the insulating film is inserted into the recess of the insulator via the stepped portion of the teeth. stata.

22. The insulator has a thin-walled portion that protrudes from the end face of the teeth toward the stepped portion, The insulating film is guided by the thin portion and inserted into the recess. The stator according to claim 21.

23. The thin-walled portion has a tip that protrudes most towards the stepped portion, If the direction perpendicular to both the extending direction and the axial direction of the teeth is defined as the tooth width direction, The width of the thin-walled portion in the tooth width direction decreases as it approaches the tip. The stator according to claim 22.

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

25. The electric motor according to claim 24, A compression mechanism driven by the aforementioned electric motor and A compressor equipped with a compressor.

26. The compressor, condenser, pressure reducing device, and evaporator are provided as described in claim 25. Refrigeration cycle device.