Stator, electric motor, compressor, and refrigeration cycle device

Abstract

In the present invention, a stator core has an annular core back, N teeth (where N is an integer of 2 or more), and N slots. The outer periphery of the core back has, on a surface orthogonal to a central axis, a first linear part that extends in a straight line, a second linear part that extends in a straight line, and an arc part that extends in an arc shape between the first linear part and the second linear part in a circumferential direction centered on the central axis. A radial straight line that passes through the circumferential direction center of a tooth is referred to as a tooth center line. A radial straight line that passes through the circumferential direction center of a slot is referred to as a slot center line. The circumferential direction center of the first linear part is positioned on a tooth center line of one of the N teeth. The circumferential direction center of the second linear part is positioned on the slot center line of one of the N slots. A recessed part that is recessed radially inward is formed in at least one the first linear part, the second linear part, and the arc part.

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 compressor includes a compression mechanism, an electric motor that drives the compression mechanism, and a sealed container that houses them. During compression, refrigerant and refrigeration oil that lubricates the compression mechanism circulate within the sealed container. The stator core of the electric motor has a notch on the outer periphery that serves as a flow path for the refrigeration oil (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2006-230054 (for example, see paragraph 0037 and FIG. 11)

[0004] To improve the reliability of the compressor, it is necessary to improve the circulation of the refrigeration oil (i.e., oil return) within the sealed container and prevent the refrigeration oil from leaking into the refrigerant circuit. To achieve this, a larger refrigeration oil flow path is desirable. However, if the notch on the outer periphery of the stator core is made larger, the magnetic path of the stator core becomes narrower, which may lead to a decrease in motor performance.

[0005] The present disclosure aims to improve the oil return property and outflow prevention performance of refrigeration oil while suppressing a decrease in motor performance.

[0006] The stator of the present disclosure includes a stator core and a coil wound around the stator core. The stator core includes an annular core back centered on a central axis, N teeth (N is an integer greater than or equal to 2) extending radially inward from the core back about the central axis, and N slots formed between each pair of adjacent teeth. The outer periphery of the core back includes, in a plane perpendicular to the central axis, a first linear portion extending linearly, a second linear portion also extending linearly, and an arc portion extending arc-shaped between the first linear portion and the second linear portion in the circumferential direction about the central axis. A radial line passing through the circumferential center of each of the N teeth is defined as a tooth centerline, and a radial line passing through the circumferential center of each of the N slots is defined as a slot centerline. The circumferential center of the first linear portion is located on the tooth centerline of one of the N teeth. The circumferential center of the second straight portion is located on the slot centerline of any one of the N slots. At least one of the first straight portion, the second straight portion, and the arc portion has a recessed portion recessed radially inward.

[0007] In the present disclosure, the stator core is provided with a first linear portion and a second linear portion, and a recess is formed in at least one of the first linear portion, the second linear portion, and the arc portion, so that the flow path area for refrigerant oil in a compressor, etc. can be secured without excessively narrowing the magnetic path in the stator core, thereby improving the oil return and outflow prevention performance of the refrigerant oil while suppressing a decrease in motor performance.

[0008] 11 is a cross-sectional view showing an electric motor according to a first embodiment. FIG. 12 is a cross-sectional view showing a rotor according to the first embodiment. FIG. 13 is a plan view showing a stator according to the first embodiment. FIG. 14 is a perspective view showing an electric motor according to the first embodiment. FIG. 15 is a plan view showing a stator core according to the first embodiment. FIG. 16 is a schematic view for explaining a first straight portion, a second straight portion, and a circular arc portion of the stator core according to the first embodiment. FIG. 17 is a first plan view for explaining the shape of the stator core according to the first embodiment. FIG. 18 is an enlarged view (A) and (B) showing a portion surrounded by dashed lines 8A and 8B in FIG. 7. FIG. 19 is a second plan view for explaining the shape of the stator core according to the first embodiment. FIG. 19 is an enlarged view (A) and (B) showing a portion surrounded by dashed lines 10A and 10B in FIG. 9. FIG. 11 is a third plan view for explaining the shape of the stator core according to the first embodiment. FIG. 12 is an enlarged view (A) and (B) showing a portion surrounded by dashed lines 12A and 12B in FIG. 11. FIG. 13 is a fourth plan view for explaining the shape of the stator core according to the first embodiment. FIG. 14 is an enlarged view showing a portion surrounded by dashed line 14 in FIG. 16A and 16B are enlarged views (A) and (B) showing the portions surrounded by dashed lines 15A and 15B in Fig. 13. Fig. 16B is a fifth plan view for explaining the shape of the stator core of embodiment 1. Fig. 16C is a plan view showing the portion surrounded by dashed line 17 in Fig. 16. Fig. 16D is a plan view showing the portion surrounded by dashed line 18 in Fig. 16. Fig. 16E is a sixth plan view for explaining the shape of the stator core of embodiment 1. Fig. 16F is a seventh plan view for explaining the shape of the stator core of embodiment 1. Fig. 16G is a diagram showing a compressor of embodiment 2. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 3. Fig. 16H is a diagram showing a compressor of embodiment 2. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 3. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 4. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 4. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 4. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 5. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 6. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 7. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 8. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 9. Fig. 16H is a diagram showing a refrigeration cycle device of embodiment 1.

[0009] Embodiment 1. <Configuration of Electric Motor> Fig. 1 is a plan view showing an electric motor 3 according to embodiment 1. The electric motor 3 according to embodiment 1 has an annular stator 1 and a rotatable rotor 5 provided inside the stator 1. An air gap of 0.25 to 1.0 mm is provided between the stator 1 and the rotor 5.

[0010] Hereinafter, the direction of the central axis Ax, which is the center of rotation of the rotor 5, will be referred to as the "axial direction." The circumferential direction centered on the central axis Ax will be referred to as the "circumferential direction." The radial direction centered on the central axis Ax will be referred to as the "radial direction."

[0011] <Configuration of the rotor> Fig. 2 is a cross-sectional view showing the rotor 5. As shown in Fig. 2, the rotor 5 has a rotor core 50 and permanent magnets 55 attached to the rotor core 50. The rotor core 50 is made by laminating electromagnetic steel sheets in the axial direction and fixing them together by caulking, rivets, or the like. The thickness of the electromagnetic steel sheets is 0.1 to 1.0 mm, and is 0.35 mm, for example.

[0012] The rotor core 50 has a cylindrical shape centered on the central axis Ax. A shaft 90 of the compressor 8 (FIG. 21) is press-fitted into a central hole 50a of the rotor core 50. The central axis of the shaft 90 coincides with the above-mentioned central axis Ax.

[0013] The rotor core 50 has a plurality of magnet insertion holes 51 along its outer periphery. Here, six magnet insertion holes 51 are arranged at equal intervals in the circumferential direction. One permanent magnet 55 is arranged in each magnet insertion hole 51.

[0014] One permanent magnet 55 constitutes one magnetic pole. Since there are six permanent magnets 55, 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 one magnet insertion hole 51.

[0015] The circumferential center of each magnet insertion hole 51 is the pole center P. A radial line passing through the pole center P is defined as the magnetic pole center line. The magnetic pole center line is the d-axis of the rotor 5. The space between adjacent magnet insertion holes 51 is defined as an inter-pole portion M.

[0016] The permanent magnet 55 is a flat plate-shaped member having a width in the circumferential direction and a thickness in the radial direction. The permanent magnet 55 is magnetized in its thickness direction, i.e., in the radial direction. The permanent magnet 55 is a neodymium rare earth magnet containing neodymium (Nd), iron (Fe), and boron (B). However, it may also be a samarium-cobalt magnet containing samarium (Sm) and cobalt (Co), or a ferrite magnet. The permanent magnet 55 is a sintered magnet made by sintering magnetic powder, but it may also be a bonded magnet made by mixing magnetic powder with resin.

[0017] A flux barrier 52 is formed at each of the circumferential ends of the magnet insertion hole 51. The flux barrier 52 is a hole that extends radially from the circumferential end of the magnet insertion hole 51 toward the outer periphery of the rotor core 50. The flux barrier 52 acts to suppress leakage flux between adjacent magnetic poles.

[0018] Radially long slits 53 are formed on the radially outer side of the magnet insertion holes 51. Here, four slits 53 are formed symmetrically with respect to the magnetic pole center line. In addition, circumferentially long side slits 54 are formed adjacent to the pole center P side of the flux barrier 52. However, the number and arrangement of the slits 53 are arbitrary. In addition, the rotor core 50 does not necessarily have to have the slits 53 and the side slits 54.

[0019] The crimped portions 59 that integrally fasten the electromagnetic steel sheets that make up the rotor core 50 are formed on radial straight lines that pass through the inter-pole portions M. The arrangement of the crimped portions 59 is not limited to the arrangement described here.

[0020] A through hole 56 is formed radially inward of the magnet insertion hole 51. Furthermore, a through hole 57 is formed radially inward of the crimped portion 59, and a through hole 58 is formed radially outward of the crimped portion 59. Each of the through holes 56, 57, and 58 extends from one axial end to the other end of the rotor core 50.

[0021] The through holes 56, 57, and 58 are used as flow paths for the refrigerant and refrigeration oil of the compressor 8 (FIG. 21). Any of the through holes 56, 57, and 58 may be used as a rivet hole. The arrangement of the through holes 56, 57, and 58 is not limited to the arrangement described here.

[0022] 1, the stator 1 has an annular stator core 10 centered on a central axis Ax, and a coil 30 wound around the stator core 10. The stator core 10 is made by stacking a plurality of electromagnetic steel plates in the axial direction and fixing them together by caulking or the like. The thickness of the electromagnetic steel plates is 0.1 to 1.0 mm, and is, for example, 0.35 mm.

[0023] 3 is a plan view showing the stator core 10. The stator core 10 has an annular core back 13 and N teeth 14 extending radially inward from the core back 13, where N is an integer equal to or greater than 2. The outer periphery of the core back 13 is fitted into the inner circumferential surface of a cylindrical shell 81 (FIG. 21). The shell 81 is part of the compressor 8 (FIG. 21) and is made of a magnetic material.

[0024] The teeth 14 are formed at equal intervals in the circumferential direction. A tooth tip 14e with a wide circumferential width is formed at the radially inner tip of each tooth 14. The tooth tip 14e of each tooth 14 faces the rotor 5 (FIG. 2). A coil 30 is wound around the teeth 14 in a distributed winding manner. The number of teeth 14 (N) is 18 in this example, but may be any number equal to or greater than two.

[0025] A slot 15 is formed between adjacent teeth 14. The number of slots 15 is the same as the number (N) of teeth 14, which is 18 in this example. A coil 30 is housed in the slot 15.

[0026] In a plane perpendicular to the central axis Ax, a radial line passing through the circumferential center of each tooth 14 is referred to as a tooth center line T. The tooth center line T is an imaginary line and includes not only the center line within the tooth 14 but also its extension.

[0027] Similarly, in a plane perpendicular to the central axis Ax, a radial line passing through the circumferential center of each slot 15 is referred to as a slot center line S. The slot center line S is an imaginary line and includes not only the center line within the slot 15 but also its extension.

[0028] Fig. 4 is a perspective view showing the electric motor 3. As shown in Fig. 4, the stator 1 has a first-phase coil 31, a second-phase coil 32, and a third-phase coil 33. For example, the first phase is U-phase, the second phase is V-phase, and the third phase is W-phase, but the combination is not limited to this. When it is not necessary to distinguish between the coils 31, 32, and 33, they will be referred to as coil 30.

[0029] Each of the coils 31, 32, and 33 has a conductor made of aluminum or copper and an insulating coating covering the conductor. The coil 31 is located at the outermost position in the radial direction, and the coil 33 is located at the innermost position in the radial direction. The coil 32 is located radially outside the coil 31 and radially inside the coil 33.

[0030] 3n coils 30 are wound around the stator core 10 for each phase, where n is an integer equal to or greater than 1. More specifically, 3n coils 31, 3n coils 32, and 3n coils 33 are wound around the stator core 10.

[0031] 4, n=1. Therefore, three coils 31, three coils 32, and three coils 33 are wound around the stator core 10. The three coils 31 are connected in series with each other, the three coils 32 are connected in series with each other, and the three coils 33 are connected in series with each other.

[0032] Three coils 31 are arranged at 120-degree intervals in the circumferential direction. Each coil 31 is wound at a pitch of three slots. Each coil 31 has a coil end 31 a extending along the end face of the stator core 10 and a coil side 31 b inserted into a slot 15.

[0033] Similarly, three coils 32 are arranged at 120-degree intervals in the circumferential direction. Each coil 32 is wound at a pitch of three slots. Each coil 32 has a coil end 32 a extending along the end face of the stator core 10 and a coil side 32 b inserted into a slot 15.

[0034] Similarly, three coils 33 are arranged at 120-degree intervals in the circumferential direction. Each coil 33 is wound at a pitch of three slots. Each coil 33 has a coil end 33 a extending along the end face of the stator core 10 and a coil side 33 b inserted into a slot 15.

[0035] The coils 31, 32, and 33 are arranged so that two of the coil ends overlap in the radial direction. The coil 32 extends from the outer circumferential side of the coil 33 to the inner circumferential side of the coil 31. Because of this arrangement, one coil side is inserted into each of the slots 15 of the stator core 10.

[0036] As described above, the electric motor 3 of the first embodiment has 6 poles, 18 slots, and a slot pitch of 3. Therefore, the winding factor kw is 1.

[0037] A centrifugal separator 60 is attached to one axial end of the shaft 90. The centrifugal separator 60 has a disk portion 61 fixed to the end of the shaft 90 via a fixed shaft 63, and a blade portion 62 fixed to the underside of the disk portion 61 (see FIG. 21). The centrifugal separator 60 is also called an oil separator.

[0038] The centrifugal separator 60 is disposed radially inward of the coil ends 31 a, 32 a, 33 a of the coils 31, 32, 33 of the stator 1. The centrifugal separator 60 discharges the refrigerant oil having a higher specific gravity outward from the refrigerant and the refrigerant oil that have passed through the through holes 56, 57, 58 ( FIG. 2 ) of the rotor 5.

[0039] The refrigeration oil discharged from the centrifugal separator 60 passes through the gaps between the stator core 10 and the coil ends 31 a, 32 a, 33 a and heads toward the outer periphery of the stator core 10. The gaps between the stator core 10 and each of the coil ends 31 a, 32 a, 33 a are referred to as stator coil gaps G.

[0040] <Outer peripheral shape of stator core 10> Figure 5 is a diagram for explaining the outer peripheral shape of the stator core 10. The outer periphery of the core back 13 of the stator core 10 has a shape in which a circle (referred to as a reference circle) C1 centered on the central axis Ax is cut out by a first linear portion 11A and a second linear portion 11B. Both the first linear portion 11A and the second linear portion 11B are surfaces parallel to the central axis Ax.

[0041] That is, the outer periphery of the core back 13 has, in a plane perpendicular to the central axis Ax, a first linear portion 11A extending linearly, a second linear portion 11B extending linearly, and an arc portion 12 extending arc-like. As shown in the perspective view of Fig. 4, the first linear portion 11A and the second linear portion 11B are both flat portions, and the arc portion 12 is an arc surface portion.

[0042] The arc portion 12 is fitted to the inner peripheral surface of a shell 81 ( FIG. 21 ) of the compressor 8. A flow path for refrigeration oil is formed between the first straight portion 11A and the shell 81. A flow path for refrigeration oil is also formed between the second straight portion 11B and the shell 81. The first straight portion 11A and the second straight portion 11B are also collectively referred to as straight portions 11.

[0043] Fig. 6 is a schematic diagram for explaining the straight portions 11A, 11B and the arc portion 12 of the stator core 10. In Fig. 6, a first straight portion recessed portion 21A, a second straight portion recessed portion 21B, and an arc portion recessed portion 22 (Fig. 5), which will be described later, are omitted.

[0044] As shown in FIG. 6, the outer periphery of the stator core 10 is made up of two first linear portions 11A, two second linear portions 11B, and four arcuate portions 12.

[0045] The two first linear portions 11A are formed to face each other across the central axis Ax. More specifically, the two first linear portions 11A are formed symmetrically with respect to each other with respect to the central axis Ax.

[0046] Each of the first straight portions 11A is formed radially outward of one of the teeth 14. More specifically, the circumferential center of each of the first straight portions 11A is located on the tooth center line T of one of the teeth 14.

[0047] The two second linear portions 11B are formed to face each other across the central axis Ax. More specifically, the two second linear portions 11B are formed symmetrically with respect to each other with respect to the central axis Ax.

[0048] Each second straight portion 11B is formed radially outward of one of the slots 15. More specifically, the circumferential center of each second straight portion 11B is located on the slot center line S of one of the slots 15.

[0049] The circumferential center of the second straight portion 11B is located at a position 90 degrees from the circumferential center of the first straight portion 11A with respect to the central axis Ax. Therefore, the outer periphery of the stator core 10 fits within a rectangular area. This shape is advantageous in terms of improving the yield when punching electromagnetic steel sheets.

[0050] The arcuate portions 12 are formed in the circumferential direction between the first linear portion 11A and the second linear portion 11B. Here, four arcuate portions 12 are formed.

[0051] To clarify the positions of the straight line portions 11A, 11B and the arc portion 12, points P1 to P8 are defined on the outer periphery of the stator core 10 in the clockwise direction in FIG.

[0052] One first straight line portion 11A has two ends at points P1 and P2, and the other first straight line portion 11A has two ends at points P5 and P6. Similarly, one second straight line portion 11B has two ends at points P3 and P4, and the other second straight line portion 11B has two ends at points P7 and P8.

[0053] Furthermore, the ends of the first arc portion 12 are points P2 and P3, the ends of the second arc portion 12 are points P4 and P5, the ends of the third arc portion 12 are points P6 and P7, and the ends of the fourth arc portion 12 are points P8 and P1.

[0054] Here, we will explain the case where the outer periphery of the stator core 10 has two first straight portions 11A, two second straight portions 11B, and four arc portions 12, but the numbers of the first straight portions 11A, second straight portions 11B, and arc portions 12 are not limited to these numbers.

[0055] 5, a first straight portion recess 21A, which is a portion recessed radially inward, is formed at the circumferential center of the first straight portion 11A. A second straight portion recess 21B, which is a portion recessed radially inward, is formed at the circumferential center of the second straight portion 11B.

[0056] An arc portion recess 22, which is a portion recessed radially inward, is formed in the arc portion 12. The arc portion recess 22 is located between the first straight portion 11A and the second straight portion 11B in the circumferential direction.

[0057] The first linear portion recess 21A, the second linear portion recess 21B and the arc portion recess 22 are all formed from one end to the other end in the axial direction of the stator core 10, and form a flow path for refrigeration oil.

[0058] In the first embodiment, a sufficient flow path for refrigerating machine oil is ensured by providing the first straight portion 11A and the second straight portion 11B in the stator core 10, as well as the first straight portion recessed portion 21A, the second straight portion recessed portion 21B, and the arc portion recessed portion 22. This improves the refrigerant oil return performance in the compressor 8 (FIG. 21), and suppresses the outflow of refrigerating machine oil into the refrigerant circuit of the refrigeration cycle device 400 (FIG. 22).

[0059] The first linear recess 21A has a triangular shape in a plane perpendicular to the central axis Ax, with the apex on the inner periphery. However, the shape of the first linear recess 21A is not limited to a triangular shape and may be, for example, rectangular or semicircular. The same applies to the shapes of the second linear recess 21B and the arcuate recess 22.

[0060] The length L1 of the first straight portion 11A in the circumferential direction and the length L2 of the second straight portion 11B in the circumferential direction satisfy the relationship L1>L2.

[0061] The first straight portion 11A is located radially outside the teeth 14, whereas the second straight portion 11B is located radially outside the slots 15. Therefore, when the distances L1 and L2 are equal (i.e., L1 = L2), the magnetic path between the second straight portion 11B and the slots 15 becomes narrow, which may cause magnetic saturation.

[0062] On the other hand, when the distances L1 and L2 satisfy the relation L1 > L2, the flow area between the straight sections 11A and 11B and the shell 81 is secured, and the magnetic path between the second straight section 11B and the slot 15 does not become too narrow, thereby suppressing the occurrence of magnetic saturation.

[0063] The first linear portion recess 21A, the second linear portion recess 21B, and the arc portion recess 22 of the stator core 10 will be described in detail below.

[0064] 7 is a first plan view illustrating the shape of stator core 10 according to the first embodiment. In FIG. 7, the point of first linear recess 21A closest to central axis Ax (i.e., the point on the innermost circumferential side) is defined as innermost point V1. A line passing through innermost point V1 and central axis Ax is defined as line N1.

[0065] The point closest to the central axis Ax (i.e., the point on the innermost periphery side) of the arcuate recess 22 is defined as the innermost point V2. A straight line passing through the innermost point V2 and the central axis Ax is defined as a straight line N2.

[0066] 7, the innermost point V1 of the first linear recess 21A is shown at a position offset in the circumferential direction from the tooth center line T. The innermost point V2 of the second linear recess 21B is also shown at a position offset in the circumferential direction from the tooth center line T.

[0067] Fig. 8A is an enlarged view of the portion surrounded by the dashed line 8A in Fig. 7. The distance from the innermost point V1 of the first linear recess 21A to the tooth center line T of the corresponding tooth 14 is defined as H1.

[0068] Furthermore, the distance from the innermost point V1 of the first straight recessed portion 21A to the slot center line S of the closest slot 15 is defined as H2. Both distances H1 and H2 are distances in the direction along a reference circle C2 that is centered on the central axis Ax and passes through the innermost point V1, i.e., the circumferential direction.

[0069] The distances H1 and H2 satisfy H1<H2.

[0070] As explained with reference to Figure 4, coils 30 are wound around the teeth 14, and refrigeration oil discharged from the centrifuge 60 passes through the gaps between the stator core 10 and the coil ends 31a, 32a, 33a (i.e., stator coil gaps G) and heads toward the outer periphery of the stator core 10.

[0071] Because the stator coil gap G is located above the teeth 14, the refrigeration oil that passes through the stator coil gap G flows most along the tooth center line T. Therefore, the closer the innermost point V1 of the first straight portion recess 21A is to the tooth center line T, the more easily the refrigeration oil that passes through the stator coil gap G flows into the first straight portion recess 21A.

[0072] Furthermore, the closer the innermost point V1 of the first straight portion recess 21A is to the slot 15, the narrower the magnetic path between the first straight portion recess 21A and the slot 15, making it more likely that magnetic saturation will occur. Therefore, it is desirable that the innermost point V1 of the first straight portion recess 21A be as far away from the slot 15 as possible.

[0073] Therefore, in the first embodiment, the distance H1 from the innermost point V1 of the first straight portion recess 21A to the tooth center line T and the distance H2 from the innermost point V1 of the first straight portion recess 21A to the slot center line S of the slot 15 closest thereto are set to satisfy H1 < H2.

[0074] 7 and 8A show an example in which the distance H1 from the innermost point V1 of the first straight portion recess 21A to the tooth center line T is longer than 0 (i.e., H1 > 0), but the distance H1 may also be 0.

[0075] Figure 8(B) is an enlarged view of the portion surrounded by dashed line 8B in Figure 7. The distance from the innermost point V2 of the arc-shaped recess 22 to the tooth center line T is defined as H1. The distance from the innermost point V2 of the arc-shaped recess 22 to the slot center line S of the closest slot 15 is defined as H2. The distances H1 and H2 satisfy H1 < H2.

[0076] As described above, the refrigeration oil that passes through the stator coil gap G flows most along the tooth center line T, so the closer the innermost point V2 of the arc portion recess 22 is to the tooth center line T, the more likely it is that the refrigeration oil that passes through the stator coil gap G will flow into the arc portion recess 22.

[0077] Furthermore, the closer the innermost point V2 of the arc-shaped recess 22 is to the slot 15, the narrower the magnetic path between the arc-shaped recess 22 and the slot 15 becomes, making it more likely that magnetic saturation will occur. Therefore, it is desirable that the innermost point V2 of the arc-shaped recess 22 be as far away from the slot 15 as possible.

[0078] Therefore, in embodiment 1, the distance H1 from the innermost point V2 of the arc-portion recess 22 to the tooth center line T and the distance H2 from the innermost point V2 of the arc-portion recess 22 to the slot center line S of the slot 15 closest thereto are set to satisfy H1 < H2.

[0079] 7 and 8B show an example in which the distance H1 from the innermost point V2 of the arc-shaped recess 22 to the tooth center line T is longer than 0 (i.e., H1>0), but the distance H1 may also be 0.

[0080] In this way, by having H1 < H2 for the first straight portion recess 21A and the arc portion recess 22, it is possible to improve the oil return and leakage prevention performance of the refrigerant oil while suppressing a decrease in motor performance.

[0081] Although an example in which H1<H2 holds for both the first straight portion recess 21A and the arc portion recess 22 has been shown here, it is sufficient that H1<H2 holds for at least one of the first straight portion recess 21A and the arc portion recess 22.

[0082] Fig. 9 is a second plan view for explaining the shape of stator core 10 according to embodiment 1. Fig. 10A is an enlarged view showing the area surrounded by dashed line 10A in Fig. 9. As shown in Fig. 10A, first linear portion recess 21A is located on tooth center line T of the corresponding tooth 14. More preferably, the innermost point V1 of first linear portion recess 21A is located on tooth center line T.

[0083] Furthermore, the first linear portion recess 21A is not located on the slot center line S of the slot 15 adjacent to the tooth 14. In other words, points E1 and E2 that define the circumferential ends of the first linear portion recess 21A are located circumferentially inward of the slot center lines S of the slots 15 on both sides of the tooth 14. In other words, the slot center line S does not pass between points E1 and E2.

[0084] Since the refrigeration oil that passes through the stator coil gap G flows most largely along the tooth center line T, the refrigeration oil can easily flow into the first straight portion recess 21A by positioning the innermost point V1 of the first straight portion recess 21A on the tooth center line T. Furthermore, since the first straight portion recess 21A is not positioned on the slot center line S, the magnetic path between the first straight portion recess 21A and the slot 15 does not become too narrow, and magnetic saturation is suppressed.

[0085] Fig. 10B is an enlarged view showing the portion surrounded by dashed line 10B in Fig. 9. As shown in Fig. 10B, the arc-shaped recess 22 is located on the tooth center line T of the corresponding tooth 14. More preferably, the innermost point V2 of the arc-shaped recess 22 is located on the tooth center line T.

[0086] Furthermore, the arc-portion recess 22 is not located on the slot center line S of the slot 15 adjacent to the tooth 14. In other words, points F1 and F2 that define the circumferential ends of the arc-portion recess 22 are located circumferentially inward of the slot center lines S of the slots 15 on both sides of the tooth 14. In other words, the slot center line S does not pass between points F1 and F2.

[0087] Since the refrigeration oil that passes through the stator coil gap G flows most largely along the tooth center line T, positioning the innermost point V2 of the arc-portion recess 22 on the tooth center line T makes it easier for the refrigeration oil to flow into the arc-portion recess 22. Furthermore, since the arc-portion recess 22 is not positioned on the slot center line S, the magnetic path between the arc-portion recess 22 and the slot 15 does not become too narrow, and the occurrence of magnetic saturation is suppressed.

[0088] In this way, since both the first straight portion recess 21A and the arc portion recess 22 are located on the tooth center line T and not on the slot center line S, it is possible to improve the refrigerant oil return and leakage prevention performance while suppressing a decrease in motor performance.

[0089] Here, an example has been described in which both the first straight portion recess 21A and the arc portion recess 22 are located on the tooth center line T but not on the slot center line S. However, a configuration in which at least one of the first straight portion recess 21A and the arc portion recess 22 is located on the tooth center line T but not on the slot center line S may also be used.

[0090] Fig. 11 is a third plan view for explaining the shape of stator core 10 according to embodiment 1. Fig. 12A is an enlarged view showing the area surrounded by dashed line 12A in Fig. 11. As shown in Fig. 12A, first linear recess 21A has a depth Dt on tooth center line T that is deeper than a depth Ds on slot center line S. That is, Dt > Ds holds.

[0091] The depths Dt and Ds of the first straight-line recess 21A are both the distance from the inner edge of the first straight-line recess 21A to a reference line C3, which is a virtual line that defines the straight line 11A. The reference line C3 is also a line connecting points E1 and E2 that define both circumferential ends of the first straight-line recess 21A.

[0092] Since the refrigeration oil that passes through the stator coil gap G flows most largely along the tooth center line T, the deep depth Dt of the first straight portion recess 21A on the tooth center line T makes it easier for the refrigeration oil to flow into the first straight portion recess 21A. Furthermore, the shallow depth Ds of the first straight portion recess 21A on the slot center line S prevents the magnetic path between the first straight portion recess 21A and the slot 15 from becoming too narrow, thereby suppressing the occurrence of magnetic saturation.

[0093] 12B, the depth Dt of the arc-portion recess 22 on the tooth center line T is deeper than the depth Ds on the slot center line S. In other words, Dt > Ds. Both depths Dt and Ds of the arc-portion recess 22 are the distances from the inner edge of the arc-portion recess 22 to the reference circle C1.

[0094] Since the refrigeration oil that has passed through the stator coil gap G flows most largely along the tooth center line T, the deep depth Dt of the arc-portion recess 22 on the tooth center line T makes it easier for the refrigeration oil to flow into the arc-portion recess 22. Furthermore, the shallow depth Ds of the arc-portion recess 22 on the slot center line S prevents the magnetic path between the arc-portion recess 22 and the slot 15 from becoming too narrow, suppressing the occurrence of magnetic saturation.

[0095] In this way, since Dt>Ds holds for the first straight portion recess 21A and the arc portion recess 22, it is possible to improve the oil return and leakage prevention performance of the refrigerant oil while suppressing a decrease in motor performance.

[0096] Although an example in which Dt>Ds holds for both the first straight portion recess 21A and the arc portion recess 22 has been shown here, it is sufficient that Dt>Ds holds for at least one of the first straight portion recess 21A and the arc portion recess 22.

[0097] 13 is a fourth plan view illustrating the shape of stator core 10 according to the first embodiment. As shown in FIG. 13 , first arc-portion recesses 22A and second arc-portion recesses 22B are formed in arc-portion 12. First arc-portion recesses 22A are located on tooth center lines T of corresponding teeth 14. Second arc-portion recesses 22B are located on slot center lines S of corresponding slots 15.

[0098] Here, the first arcuate recess 22A is located on the first straight portion 11A side, and the second arcuate recess 22B is located on the second straight portion 11B side, but the arrangement of the arcuate recesses 22A and 22B may be reversed.

[0099] Fig. 14 is an enlarged view showing the portion surrounded by dashed line 14 in Fig. 13. As shown in Fig. 14, in a plane perpendicular to the central axis Ax, the first arc-shaped recess 22A has an area S1, and the second arc-shaped recess 22B has an area S2.

[0100] The area S1 is the area of ​​the region surrounded by the inner edge of the first arc-shaped recess 22A and the reference circle C1. The area S2 is the area of ​​the region surrounded by the inner edge of the second arc-shaped recess 22B and the reference circle C1.

[0101] The areas S1 and S2 of the first arcuate recess 22A and the second arcuate recess 22B satisfy S1>S2.

[0102] As described above, the refrigeration oil that has passed through the stator coil gap G flows radially outward on the teeth 14, and therefore the large area S1 of the first arc-shaped recess 22A makes it easier for the refrigeration oil to flow into the first arc-shaped recess 22A. Furthermore, the small area S2 of the second arc-shaped recess 22B prevents the magnetic path between the second arc-shaped recess 22B and the slot 15 from becoming too narrow, thereby suppressing the occurrence of magnetic saturation.

[0103] 14, the circumferential length W1 of the first arc-shaped recess 22A is longer than the circumferential length W2 of the second arc-shaped recess 22B, and the radial depth D1 of the first arc-shaped recess 22A is deeper than the radial depth D2 of the second arc-shaped recess 22B. However, this is not a limitation, and any other suitable configuration may be used as long as the above relationship S1>S2 is satisfied.

[0104] In this way, by the areas S1 and S2 of the first arc-shaped recess 22A and the second arc-shaped recess 22B satisfying S1 > S2, it is possible to improve the oil return and leakage prevention performance of the refrigerant oil while suppressing a decrease in motor performance.

[0105] Fig. 15A is an enlarged view showing the portion surrounded by the dashed line 15A in Fig. 13. As shown in Fig. 15A, the first linear recess 21A is located on the tooth center line T of the corresponding tooth 14.

[0106] The first linear portion recess 21A has an area S3 in a plane perpendicular to the central axis Ax. The area S3 is the area of ​​a region surrounded by the inner edge of the first linear portion recess 21A and the reference line C3 that defines the first linear portion 11A.

[0107] Fig. 15(B) is an enlarged view showing the portion surrounded by the dashed line 15B in Fig. 13. As shown in Fig. 15(B), the second linear recess 21B is located on the slot center line S of the corresponding slot 15.

[0108] Second linear portion recess 21B has an area S4 in a plane perpendicular to central axis Ax, which is the area of ​​a region surrounded by the inner edge of second linear portion recess 21B and reference line C4 that defines second linear portion 11B.

[0109] As shown in FIGS. 15A and 15B, the areas S3 and S4 of the linear recesses 21A and 21B satisfy S3>S4.

[0110] As described above, the refrigeration oil that has passed through the stator coil gap G flows radially outward on the teeth 14, and therefore the large area S3 of the first straight portion recess 21A makes it easier for the refrigeration oil to flow into the first straight portion recess 21A. Furthermore, the small area S4 of the second straight portion recess 21B prevents the magnetic path between the second straight portion recess 21B and the slot 15 from becoming too narrow, thereby suppressing the occurrence of magnetic saturation.

[0111] 15A and 15B, the circumferential length W3 of the first straight portion recess 21A is longer than the circumferential length W4 of the second straight portion recess 21B, and the radial depth D3 of the first straight portion recess 21A is deeper than the radial depth D4 of the second straight portion recess 21B. However, this is not a limitation, and any other suitable configuration may be used as long as the above relationship S3>S4 is satisfied.

[0112] In this way, by having the areas S3 and S4 of the first straight portion recess 21A and the second straight portion recess 21B satisfy S3 > S4, it is possible to improve the oil return and leakage prevention performance of the refrigerant oil while suppressing a decrease in motor performance.

[0113] 16 is a fifth plan view illustrating the shape of stator core 10 according to embodiment 1. As shown in FIG. 16 , first arc-portion recesses 22A and second arc-portion recesses 22B are formed in arc-portion 12. First arc-portion recesses 22A are located on tooth center lines T of corresponding teeth 14, and second arc-portion recesses 22B are located on slot center lines S of corresponding slots 15.

[0114] Fig. 17 is an enlarged view showing the portion surrounded by dashed line 17 in Fig. 16. As shown in Fig. 17, first arcuate recess 22A has an area S1, and first linear recess 21A has an area S3. Area S1 is as described with reference to Fig. 14. Area S3 is as described with reference to Fig. 15(A).

[0115] The areas S1 and S3 of the first arcuate recess 22A and the first linear recess 21A satisfy S1>S3.

[0116] Both first straight portion recess 21A and first arc portion recess 22A are located on tooth center line T, but first straight portion 11A is closer to central axis Ax than arc portion 12. Therefore, when areas S1 and S3 are equal (i.e., S1 = S3), the magnetic path between first straight portion recess 21A and slot 15 becomes narrow, which may cause magnetic saturation.

[0117] Since the area S3 of the first straight portion recess 21A is smaller than the area S1 of the first arc portion recess 22A (i.e., S1 > S3), the magnetic path between the first straight portion recess 21A and the slot 15 does not become too narrow, and the occurrence of magnetic saturation is suppressed.

[0118] 17, the circumferential length W1 of the first arc-portion recess 22A is longer than the circumferential length W3 of the first linear portion recess 21A, and the radial depth D1 of the first arc-portion recess 22A is deeper than the radial depth D3 of the first linear portion recess 21A. However, this is not a limitation, and any other suitable configuration may be used as long as the above relationship S1>S3 is satisfied.

[0119] In this way, by making the areas S1 and S3 of the first arc recess 22A and the first straight recess 21A satisfy S1 > S3, the occurrence of magnetic saturation can be suppressed and the deterioration of motor performance can be suppressed.

[0120] Figure 18 is an enlarged view showing the portion surrounded by dashed line 18 in Figure 16. As shown in Figure 18, second arcuate recess 22B has area S2, and second linear recess 21B has area S4. Area S2 is as described with reference to Figure 14. Area S4 is as described with reference to Figure 15(B). Areas S2 and S4 satisfy S2 > S4.

[0121] Both the second linear portion recess 21B and the second arc portion recess 22B are located on the slot center line S, but the second linear portion 11B is closer to the central axis Ax than the arc portion 12. Therefore, when the areas S2 and S4 are equal (i.e., S2 = S4), the magnetic path between the second linear portion recess 21B and the slot 15 becomes narrow, and magnetic saturation may occur.

[0122] Since the area S4 of the second straight portion recess 21B is smaller than the area S2 of the second arc portion recess 22B (i.e., S2 > S4), the magnetic path between the second straight portion recess 21B and the slot 15 does not become too narrow, and the occurrence of magnetic saturation is suppressed.

[0123] In this example, the circumferential length W2 of the second arc-portion recess 22B is longer than the circumferential length W4 of the second linear portion recess 21B, and the radial depth D2 of the second arc-portion recess 22B is deeper than the radial depth D4 of the second linear portion recess 21B. However, this example is not limiting, and it is sufficient that the above relationship S2>S4 is satisfied.

[0124] In this way, by making the areas S2 and S4 of the second arc recess 22B and the second straight recess 21B satisfy S2 > S4, the occurrence of magnetic saturation can be suppressed and the deterioration of motor performance can be suppressed.

[0125] Fig. 19 is a sixth plan view for illustrating the shape of stator core 10 according to embodiment 1. As shown in Fig. 19, arc portion 12 is formed with first arc portion recess 22C and second arc portion recess 22D.

[0126] The first arcuate recess 22C is located on the tooth center line T of the corresponding tooth 14, and the second arcuate recess 22D is located on the tooth center line T of the corresponding tooth 14. Furthermore, the first arcuate recess 22C is located on the first straight portion 11A side, and the second arcuate recess 22D is located on the second straight portion 11B side.

[0127] In a plane perpendicular to the central axis Ax, the first arc-shaped recess 22C has an area S5, and the second arc-shaped recess 22D has an area S6. Area S5 is the area of ​​the region enclosed by the inner edge of the first arc-shaped recess 22C and the reference circle C1. Area S6 is the area of ​​the region enclosed by the inner edge of the second arc-shaped recess 22D and the reference circle C1.

[0128] The areas S5 and S6 of the first arcuate recess 22C and the second arcuate recess 22D satisfy S5<S6.

[0129] The area of ​​the flow path formed between the second straight portion 11B and the shell 81 (FIG. 21) is smaller than the area of ​​the flow path formed between the first straight portion 11A and the shell 81. Therefore, by making the area S6 of the second arc-shaped recess 22D adjacent to the second straight portion 11B larger than the area S5 of the first arc-shaped recess 22C, the flow rate of the refrigerating machine oil can be increased.

[0130] In this way, by making the areas S5, S6 of the first arc-shaped recess 22C and the second arc-shaped recess 22D satisfy S5 < S6, the oil return property and leakage prevention performance of the refrigeration oil can be improved.

[0131] Fig. 20 is a seventh plan view illustrating the shape of stator core 10 according to embodiment 1. As shown in Fig. 20, arc-portion recesses 22 are formed in arc-portion 12. Arc-portion recesses 22 are formed on tooth center lines T of corresponding teeth 14.

[0132] The distance from the arc-portion recess 22 to the first linear portion 11A is defined as B1, and the distance from the arc-portion recess 22 to the second linear portion 11B is defined as B2. Distance B1 is the distance from end F1 of the arc-portion recess 22 on the first linear portion 11A side to point P2, which is the boundary between the first linear portion 11A and the arc portion 12. Distance B2 is the distance from end F2 of the arc-portion recess 22 on the second linear portion 11B side to point P3, which is the boundary between the second linear portion 11B and the arc portion 12.

[0133] A distance B1 from the arc-portion recess 22 to the first linear portion 11A and a distance B2 from the arc-portion recess 22 to the second linear portion 11B satisfy B1 > B2. In other words, the arc-portion recess 22 is formed at a position closer to the second linear portion 11B than the circumferential center of the arc portion 12.

[0134] As described above, the area of ​​the flow path formed between the second straight portion 11B and the shell 81 ( FIG. 21 ) is smaller than the area of ​​the flow path formed between the first straight portion 11A and the shell 81. Therefore, by positioning the arc-shaped recess 22 closer to the second straight portion 11B than to the first straight portion 11A, the flow rate of the refrigeration oil can be increased.

[0135] In this way, by making the distance B1 from the arc recess 22 to the first straight portion 11A and the distance B2 from the arc recess 22 to the second straight portion 11B satisfy B1 > B2, the oil return property and leakage prevention performance of the refrigerant oil can be improved.

[0136] Although the stator core 10 has 18 slots in this example, the number of slots is not limited to 18 and may be, for example, 24, 36, or the like.

[0137] Furthermore, although an example in which a first straight portion recess 21A is formed on both of the two first straight portions 11A has been described here, it is sufficient that a first straight portion recess 21A is formed on at least one of the first straight portions 11A.

[0138] Similarly, although an example in which second straight portion recesses 21B are formed in both of the two second straight portions 11B has been described here, it is sufficient that second straight portion recesses 21B are formed in at least one second straight portion 11B.

[0139] Similarly, although an example in which the arc-portion recesses 22 are formed in all four arc-portions 12 has been described here, it is sufficient that the arc-portion recesses 22 are formed in at least one arc-portion 12 .

[0140] Further, although an example has been described in which a first straight portion recess 21A is formed in the first straight portion 11A, a second straight portion recess 21B is formed in the second straight portion 11B, and an arc portion recess 22 is formed in the arc portion 12, it is sufficient that a recess is formed in at least one of the first straight portion 11A, the second straight portion 11B, and the arc portion 12.

[0141] <Effects of the embodiment> As described above, in the stator 1 according to the first embodiment, the stator core 10 has an annular core back 13, N (N is an integer of 2 or greater) teeth 14, and N slots 15. The outer periphery of the core back 13 has, in a plane perpendicular to the central axis Ax, a first straight portion 11A extending linearly, a second straight portion 11B extending linearly, and an arc portion 12 extending arc-like in the circumferential direction between the first straight portion 11A and the second straight portion 11B. The circumferential center of the first straight portion 11A is located on the tooth center line T of one of the teeth 14. The circumferential center of the second straight portion 11B is located on the slot center line S of one of the slots 15. At least one of the first straight portion 11A, the second straight portion 11B and the arc portion 12 has a recessed portion recessed radially inward (i.e., at least one of the first straight portion recessed portion 21A, the second straight portion recessed portion 21B and the arc portion recessed portion 22).

[0142] In this way, the first straight portion 11A and the second straight portion 11B are provided in the stator core 10, and further, a recess is provided in at least one of the first straight portion 11A, the second straight portion 11B, and the arc portion 12, so that a sufficient flow path for the refrigerant oil can be secured without excessively narrowing the magnetic path within the stator core 10. In other words, it is possible to improve the oil return property and the outflow prevention performance of the refrigerant oil while avoiding a decrease in motor performance.

[0143] Furthermore, the coils 30 are wound around the stator core 10 in a distributed winding manner, with 3n coils per phase (n is an integer greater than or equal to 1), and the winding factor is 1, so that the magnetic flux of the permanent magnet 55 can be linked to the coils 30 most efficiently, thereby improving the performance of the electric motor.

[0144] Furthermore, since the stator core 10 has 18 slots 15 (i.e., N = 18), it is possible to realize an electric motor 3 in which the stator core 10 has the first straight portion 11A, the second straight portion 11B, and the arc portion 12 as described above, and in which the winding factor is 1.

[0145] Second Embodiment Next, a compressor 8 according to a second embodiment will be described. Fig. 21 is a cross-sectional view showing the compressor 8. The compressor 8 here is a rotary compressor.

[0146] The compressor 8 includes a sealed container 80, a compression mechanism 9 disposed in the sealed container 80, an electric motor 3 that drives the compression mechanism 9, a shaft 90 that connects the electric motor 3 and the compression mechanism 9, and a centrifuge 60 fixed to the shaft 90. The configuration of the electric motor 3 is as described in the first embodiment.

[0147] The centrifuge 60 is disposed above the rotor 5 of the electric motor 3 and radially inside the coil 30 of the stator 1. The centrifuge 60 has a disk portion 61 fixed to the upper end of the shaft 90 via a fixed shaft 63, and a blade portion 62 fixed to the underside of the disk portion 61.

[0148] 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 a shell 81 and an upper container part 82. Attached to the upper container part 82 are a glass terminal 83 serving as a terminal part for supplying electric power to the electric motor 3 from outside the compressor 8, and a discharge pipe 85 for discharging the refrigerant compressed in the compressor 8 to the outside. The shell 81 houses the electric motor 3 and the compression mechanism 9.

[0149] The compression mechanism 9 has an annular first cylinder 91 and a second cylinder 92 arranged along the shaft 90. The first cylinder 91 and the second cylinder 92 are fixed to the inner periphery of the shell 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.

[0150] 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.

[0151] 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.

[0152] An oil reservoir 86 is provided at the bottom of the shell 81 to store refrigeration oil for lubricating the sliding parts of the compression mechanism 9. The refrigeration oil flows up through a hole 90a formed in the axial direction inside the shaft 90, and is supplied to the sliding parts of the compression mechanism 9 from oil supply holes 90b (only one of which is shown in FIG. 21 ) formed at multiple locations on the shaft 90.

[0153] The stator 1 of the electric motor 3 is attached to the inside of the shell 81 by shrink fitting. Electric power is supplied to the coil 30 of the stator 1 through lead wires 84 from glass terminals 83 attached to the upper part 82 of the case. The rotor 5 is fixed to the shaft 90 as described above.

[0154] An accumulator 87 that stores refrigerant gas is attached to the shell 81. The accumulator 87 is attached, for example, to the outside of the shell 81. A pair of suction pipes 88, 89 are attached to the shell 81, and refrigerant gas is supplied from the accumulator 87 to cylinders 91, 92 via the suction pipes 88, 89.

[0155] 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.

[0156] (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.

[0157] The basic operation of the compressor 8 is as follows: Refrigerant gas supplied from the accumulator 87 is supplied to each cylinder chamber of the first cylinder 91 and the second cylinder 92 through suction pipes 88 and 89. When the electric motor 3 is driven to rotate the rotor 5, the shaft 90 rotates together with the rotor 5.

[0158] When the shaft 90 rotates, a first piston 93 and a second piston 94 fitted to the shaft 90 rotate eccentrically within the respective cylinder chambers of the cylinders 91 and 92, compressing the refrigerant. The compressed refrigerant is discharged from the cylinders 91 and 92 and flows upward through the through holes 56, 57, and 58 (FIG. 2) of the rotor 5.

[0159] Meanwhile, refrigeration oil stored in oil reservoir 86 at the bottom of compressor 8 flows upward through hole 90a formed in shaft 90 and is supplied through oil supply hole 90b to each sliding part of compression mechanism 9. In addition, some of the refrigeration oil flows upward together with the refrigerant through through holes 56, 57, 58 (FIG. 2) of rotor 5.

[0160] The refrigerant and refrigerating machine oil that have passed through the through holes 56, 57, 58 of the rotor 5 collide with the centrifugal separator 60. Since the refrigerating machine oil has a higher specific gravity than the refrigerant, it is discharged by the centrifugal separator 60 radially outward.

[0161] Therefore, the refrigerant rises further within the shell 81, is discharged from the discharge pipe 85, and is sent to the refrigerant circuit of the refrigeration cycle device 400 (FIG. 22).

[0162] Meanwhile, refrigeration oil discharged from the centrifuge 60 passes through the gap between the stator core 10 and the coil 30, heads radially outward, collides with the inner surface of the shell 81, and flows into the flow passage between the straight portions 11A, 11B (including the straight portion recessed portions 21A, 21B) of the stator core 10 and the shell 81, and into the flow passage between the arc portion recessed portion 22 and the shell 81. The refrigeration oil flows downward through the flow passage and returns to the oil reservoir 86.

[0163] The smooth circulation of the refrigerating machine oil within the compressor 8 prevents the refrigerating machine oil from being discharged together with the refrigerant from the discharge pipe 85. This prevents the refrigerating machine oil from being mixed into the refrigerant circuit of the refrigeration cycle device, and also prevents a shortage of refrigerating machine oil for lubricating the compression mechanism 9.

[0164] The compressor 8 of the second embodiment has the electric motor 3 described in the first embodiment, and therefore can improve the oil return property and the outflow prevention performance of the refrigeration oil, thereby preventing the refrigeration oil from being mixed into the refrigerant circuit of the refrigeration cycle device and preventing a shortage of the refrigeration oil for lubricating the compression mechanism 9.

[0165] Furthermore, because the centrifugal separator 60 is disposed radially inside the coil ends 31 a, 32 a, 33 a of the coil 30 of the stator 1, the refrigeration oil discharged from the centrifuge 60 can be directed through the gaps between the stator core 10 and the coil ends 31 a, 32 a, 33 a toward the straight portions 11A, 11B (including the straight portion recesses 21A, 21B) and the arc portion recesses 22. This further improves the oil return property and outflow prevention performance of the refrigeration oil.

[0166] Embodiment 3 Next, a refrigeration cycle apparatus 400 according to embodiment 3 will be described. Fig. 22 is a diagram showing the refrigeration cycle apparatus 400. The refrigeration cycle apparatus 400 is, for example, an air conditioner, but is not limited thereto and may be, for example, a refrigerator.

[0167] 22 includes a compressor 401, a condenser 402 that condenses a refrigerant, a pressure reducing device 403 that reduces the pressure of the refrigerant, and an evaporator 404 that evaporates the refrigerant. The compressor 401, the condenser 402, and the pressure reducing device 403 are provided in an outdoor unit 410, and the evaporator 404 is provided in an indoor unit 420.

[0168] The compressor 401, condenser 402, pressure reducing device 403, and evaporator 404 are connected by refrigerant piping 407 to form a refrigerant circuit. The compressor 401 is configured as the compressor 8 (FIG. 21) described in the second embodiment. The refrigeration cycle apparatus 400 also includes an outdoor fan 405 facing the condenser 402 and an indoor fan 406 facing the evaporator 404.

[0169] The refrigeration cycle apparatus 400 operates as follows: The compressor 401 compresses the refrigerant it draws in and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 402 exchanges heat between the refrigerant sent out from the compressor 401 and outdoor air sent by the outdoor air blower 405, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 403 expands the liquid refrigerant sent out from the condenser 402 and sends it out as low-temperature, low-pressure liquid refrigerant.

[0170] The evaporator 404 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 403 and the indoor air, evaporating the refrigerant and sending it out as refrigerant gas. The air from which heat has been removed by the evaporator 404 is supplied into the room by the indoor fan 406.

[0171] In the refrigeration cycle apparatus 400 of the third embodiment, the compressor 401 is configured as the compressor 8 described in the second embodiment, and therefore, the intrusion of refrigeration oil into the refrigerant circuit is prevented. Therefore, it is possible to prevent a decrease in operating efficiency due to the intrusion of refrigeration oil, and it is possible to improve the operating efficiency of the refrigeration cycle apparatus 400.

[0172] 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.

[0173] DESCRIPTION OF SYMBOLS 1 stator, 5 rotor, 8 compressor, 9 compression mechanism, 10 stator core, 11A first straight portion, 11B second straight portion, 12 arc portion, 13 core back, 14 teeth, 15 slots, 21A first straight portion recessed portion (recessed portion), 21B second straight portion recessed portion (recessed portion), 22 arc portion recessed portion (recessed portion), 22A, 22C first arc portion recessed portion (recessed portion), 22B, 22D second arc portion recessed portion (recessed portion), 30, 31, 32, 33 coil, 31a, 32a, 33a coil end, 50 rotor core, 51 magnet insertion hole, 55 permanent magnet, 56, 57, 58 through hole, 60 centrifuge, 80: sealed container, 81: shell, 86: oil reservoir, 90: shaft, 400: refrigeration cycle device, 401: compressor, 402: condenser, 403: pressure reducing device, 404: evaporator, G: stator coil gap, S: slot center line, T: teeth center line.

Claims

1. Stator core and The coil wrapped around the stator core and It has, The stator core is, An annular core back centered on the central axis, N teeth (where N is an integer of 2 or more) extend radially inward from the core back with respect to the central axis, N slots are formed between two adjacent teeth among the N teeth mentioned above. It has, The outer circumference of the core back has, in a plane perpendicular to the central axis, a first straight portion extending in a straight line, a second straight portion extending in a straight line, and an arc portion extending in an arc shape between the first straight portion and the second straight portion in the circumferential direction about the central axis. The radial line passing through the circumferential center of each of the N teeth is defined as the tooth centerline. The radial line passing through the circumferential center of each of the N slots is defined as the slot centerline. The circumferential center of the first straight section is located on the tooth centerline of any of the N teeth, The circumferential center of the second straight section is located on the slot centerline of any of the N slots, Each of the first straight section, the second straight section, and the arc section has a recessed portion that is recessed inward in the radial direction. stata.

2. The coil is wound around the stator core in a distributed winding pattern, with 3n coils per phase (where n is an integer greater than or equal to 1), and the winding coefficient is 1. The stator according to claim 1.

3. N is 18. The stator according to claim 1 or 2.

4. The circumferential length L1 of the first straight section and the circumferential length L2 of the second straight section satisfy L1 > L2. The stator according to claim 1 or 2.

5. The recessed portion is located on the tooth centerline of any of the N teeth, The point in the recess closest to the central axis is defined as the innermost point. Let H1 be the distance from the innermost point of the recess to the center line of the tooth. If H2 is the distance from the innermost point of the recess to the slot centerline of the slot closest to the innermost point among the N slots, H1 < H2 holds true. The stator according to claim 1 or 2.

6. The recessed portion is located on the tooth centerline of any of the N teeth, and is not located on the slot centerline of any slot adjacent to that tooth in the circumferential direction. The stator according to claim 1 or 2.

7. The recessed portion is located on the tooth centerline of any of the N teeth, The recessed portion has a depth Dt on the tooth centerline and a depth Ds on the slot centerline. Dt > Ds holds true. The stator according to claim 1 or 2.

8. The arc portion is formed with a first arc portion recess, which is located on the tooth centerline of any of the N teeth, and a second arc portion recess, which is located on the slot centerline of any of the N slots. In the plane perpendicular to the central axis, the area S1 of the first arc recess and the area S2 of the second arc recess satisfy S1 > S2. The stator according to claim 1 or 2.

9. The first straight section has a first straight section recess formed therein, which is located on the tooth centerline of any of the N teeth. The second straight section has a second straight section recess formed on the center line of one of the N slots, In the plane perpendicular to the central axis, the area S3 of the first straight recess and the area S4 of the second straight recess satisfy S3 > S4. The stator according to claim 1 or 2.

10. The first straight section has a first straight section recess formed therein, which is located on the tooth centerline of any of the N teeth. The aforementioned arc portion has an arc recess formed on the tooth centerline of any of the N teeth, In the plane perpendicular to the central axis, the area S1 of the arc recess and the area S3 of the first straight recess satisfy S1 > S3. The stator according to claim 1 or 2.

11. The arc portion has an arc recess that is located on the center line of one of the N slots, and The second straight section has a second straight section recess formed on the center line of one of the N slots, In the plane perpendicular to the central axis, the area S2 of the arc recess and the area S4 of the second straight recess satisfy S2 > S4. The stator according to claim 1 or 2.

12. The arc portion has a first arc portion recess and a second arc portion recess formed therein. The first arc recess and the second arc recess are arranged in this order from the first straight section toward the second straight section. In the plane perpendicular to the central axis, the area S5 of the first arc recess and the area S6 of the second arc recess satisfy S5 < S6. The stator according to claim 1 or 2.

13. The distance B1 from the recessed portion of the arc to the first straight portion and the distance B2 from the recessed portion of the arc to the second straight portion satisfy B1 > B2. The stator according to claim 1 or 2.

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

15. The electric motor according to claim 14, A compression mechanism driven by the aforementioned electric motor, A shaft connecting the electric motor and the compression mechanism, A centrifugal separator fixed to the aforementioned shaft and A compressor equipped with a compressor.

16. The centrifugal separator is located radially inward of the coil ends of the coils of the stator. The compressor according to claim 15.

17. A compressor according to claim 15, a condenser, a pressure reducing device, and an evaporator are included. Refrigeration cycle device.