Stator of an electric motor, electric motor, compressor, and refrigeration cycle system

Abstract

To provide a stator that can increase the cooling efficiency of an electric motor and thereby increase its output. [Solution] The stator of the electric motor comprises a stator core having a yoke, a plurality of teeth, and a plurality of slots, and windings. The yoke has a groove and a hole. The groove is a recess in the outer circumferential surface of the yoke that extends in the axial direction, which is the direction in which the rotation shaft of the electric motor extends, allowing coolant to pass through. The hole penetrates the yoke in the axial direction. In a cross-section perpendicular to the stator core with respect to the axial direction, the groove is positioned on a virtual line that substantially bisects the teeth in the circumferential direction, and the hole is positioned such that the shortest distance between the opening edge of the hole and the inner circumferential surface of the yoke is greater than or equal to the shortest distance between the groove and the inner circumferential surface of the yoke.

Description

Technical Field

[0001] Embodiments of the present invention relate to a stator, a motor including the stator, a compressor including the motor, and a refrigeration cycle apparatus including the compressor.

Background Art

[0002] For example, a motor used in a hermetic compressor includes a substantially cylindrical stator (hereinafter referred to as a stator) and a rotor (hereinafter referred to as a rotor) rotatably provided with respect to the stator. The stator has, for example, a stator core (hereinafter referred to as a stator core) and windings (hereinafter referred to as coils). The stator core is composed of a substantially cylindrical yoke and a plurality of teeth protruding radially inward from the yoke. The coils are wound around each tooth arranged at a predetermined interval in the circumferential direction of the yoke.

[0003] In recent years, higher output of motors has been demanded. As one of the means therefor, adoption of a split core that divides the stator into a plurality of parts is cited in order to effectively utilize the winding area of the coils in the stator.

[0004] For example, the relative positions of the yoke portion and the tooth portion are designed so that wires can be wound around a plurality of split cores in an aligned state. The yoke portion is a portion corresponding to the yoke of the stator, and the tooth portion is a portion corresponding to the teeth of the stator. As an example, the split core is configured such that the inner circumference of the yoke portion is perpendicular to the center line of the tooth portion.

[0005] Furthermore, in order to increase the output of an electric motor, it is necessary to cool the motor efficiently. For this reason, the stator may have passages on its outer circumference through which a coolant, such as a refrigerant, can pass. The larger the cross-sectional area of ​​such passages, the easier it is for the coolant to pass through, thereby improving the cooling efficiency of the electric motor. On the other hand, the outer circumference of the stator becomes the mating surface with the sealed container when the stator is shrink-fitted into the sealed container of a compressor, for example. Therefore, if passages are provided on the outer circumference of the stator, the mating surface with the sealed container becomes smaller by the amount of the passages. Consequently, the larger the passages in the stator, the easier it is to reduce the holding force of the stator against the sealed container when shrink-fitting the stator, which can lead to a decrease in the reliability of the compressor. In addition, if the holding force of the stator against the sealed container is satisfied, the stress generated in the stator increases, which may lead to a decrease in efficiency due to deterioration of the magnetic properties of the motor's core. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 7163948 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention was made based on the above, and its purpose is to provide a stator that can improve the cooling efficiency of an electric motor and thereby increase its output. [Means for solving the problem]

[0008] According to the embodiment, the stator of the electric motor comprises a stator core and windings. The stator core is cylindrical in shape and surrounds a rotor that is fixed to a rotating shaft and rotates the rotating shaft. The windings are wound around the stator core. The stator core has a yoke, a plurality of teeth, and a plurality of slots. The yoke is cylindrical in shape and concentric with the rotor and surrounds the rotor. Each of the plurality of teeth protrudes radially inward from the yoke and is spaced apart in the circumferential direction of the yoke. The plurality of slots are formed between adjacent teeth in the circumferential direction and accommodate the windings. The yoke has grooves and holes. The grooves recess the outer surface of the yoke in the axial direction, which is the direction in which the rotating shaft extends, allowing coolant to pass through. The holes penetrate the yoke in the axial direction. In a cross-section perpendicular to the stator core with respect to the axial direction, the groove is positioned on a virtual line that substantially bisects the teeth in the circumferential direction, and the hole is positioned such that the shortest distance between the opening edge of the hole and the inner circumferential surface of the yoke is greater than or equal to the shortest distance between the groove and the inner circumferential surface of the yoke. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic circuit diagram showing the configuration of an air conditioner according to the first embodiment. [Figure 2] This is a schematic longitudinal cross-sectional view showing a compressor according to the first embodiment. [Figure 3] This is a schematic diagram showing the electric motor according to the first embodiment from above. [Figure 4] Figure 3 is a schematic cross-sectional view of the divided core of the electric motor, perpendicular to the axial direction, showing the configuration of the divided core. [Figure 5] This is a schematic cross-sectional view of the divided core of an electric motor according to a second embodiment, perpendicular to the axial direction of the divided core. [Modes for carrying out the invention]

[0010] (First embodiment) Embodiments of the present invention will be described below with reference to the drawings. The applications of the electric motor according to the present invention are not particularly limited. In this embodiment, the case in which it is used in the electric motor section of a rotary compressor (hereinafter simply referred to as a compressor) of an air conditioner will be described as an example. The electric motor section is the drive source for the compression mechanism that compresses the refrigerant in the compressor.

[0011] Figure 1 is a circuit diagram of the refrigeration cycle of the air conditioner 1 according to this embodiment. The air conditioner 1 is a device that performs air conditioning by such a refrigeration cycle, and is an example of a refrigeration cycle device. The air conditioner 1 mainly comprises a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an outdoor fan 401, an expansion device 5, an indoor heat exchanger 6, and an indoor fan 601.

[0012] As shown in Figure 1, the refrigerant discharge side of the compressor 2 is connected to the first port 3a of the four-way valve 3. The second port 3b of the four-way valve 3 is connected to the outdoor heat exchanger 4. The outdoor heat exchanger 4 is connected to the indoor heat exchanger 6 via the expansion device 5. The indoor heat exchanger 6 is connected to the third port 3c of the four-way valve 3. The fourth port 3d of the four-way valve 3 is connected to the refrigerant suction side of the compressor 2 via the accumulator 8. The refrigerant circulates through a circulation circuit 7 from the discharge side of the compressor 2, through the outdoor heat exchanger 4, expansion device 5, indoor heat exchanger 6, and accumulator 8, to the suction side. Any refrigerant can be used, but preferably low-pressure refrigerants such as R290, R454B, or R454C are used.

[0013] For example, when the air conditioner 1 operates in cooling mode, the four-way valve 3 switches so that the first port 3a communicates with the second port 3b, and the third port 3c communicates with the fourth port 3d. When the air conditioner 1 starts operating in cooling mode, the high-temperature, high-pressure gaseous refrigerant compressed by the compressor 2 is discharged into the circulation circuit 7. The discharged gaseous refrigerant is guided through the four-way valve 3 to the outdoor heat exchanger 4, which functions as a condenser (heat radiator).

[0014] The gaseous refrigerant introduced into the outdoor heat exchanger 4 condenses through heat exchange with the air (outside air) drawn in by the outdoor fan 401, changing into a high-pressure liquid-phase refrigerant. The high-pressure liquid-phase refrigerant is reduced in pressure as it passes through the expansion device 5, changing into a low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is introduced into the indoor heat exchanger 6, which functions as an evaporator (heat absorber), and also exchanges heat with the air (inside air) drawn in by the indoor fan 601 as it passes through the indoor heat exchanger 6.

[0015] As a result, the two-phase gaseous refrigerant absorbs heat from the air and evaporates, changing into a low-temperature, low-pressure gaseous refrigerant. The air passing through the indoor heat exchanger 6 is cooled by the latent heat of vaporization of the liquid-phase refrigerant and sent as cool air to the areas to be air-conditioned (cooled) by the indoor blower 601.

[0016] The low-temperature, low-pressure gaseous refrigerant that has passed through the indoor heat exchanger 6 is guided to the accumulator 8 via the four-way valve 3. If any liquid refrigerant that has not evaporated is mixed in with the refrigerant, it is separated into liquid and gaseous refrigerant here. The low-temperature, low-pressure gaseous refrigerant separated from the liquid refrigerant is drawn from the accumulator 8 to the compressor 2, where it is compressed again into high-temperature, high-pressure gaseous refrigerant and discharged into the circulation circuit 7.

[0017] On the other hand, when the air conditioner 1 operates in heating mode, the four-way valve 3 switches so that the first port 3a communicates with the third port 3c and the second port 3b communicates with the fourth port 3d. When the air conditioner 1 starts operating in heating mode, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 2 is guided to the indoor heat exchanger 6 via the four-way valve 3 and undergoes heat exchange with the air passing through the indoor heat exchanger 6. In this case, the indoor heat exchanger 6 functions as a condenser.

[0018] As a result, the gaseous refrigerant passing through the indoor heat exchanger 6 condenses by exchanging heat with the air (indoor air) drawn in by the indoor blower 601, and changes into a high-pressure liquid refrigerant. The air passing through the indoor heat exchanger 6 is heated by the heat exchange with the gaseous refrigerant and sent as warm air to the areas that need air conditioning (heating) by the indoor blower 601.

[0019] The high-temperature liquid-phase refrigerant that has passed through the indoor heat exchanger 6 is guided to the expansion device 5 and is depressurized in the process of passing through the expansion device 5 to change into a low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is guided to the outdoor heat exchanger 4 that functions as an evaporator and evaporates by exchanging heat with the air (outside air) sucked in by the outdoor blower 401, changing into a low-temperature and low-pressure gas-phase refrigerant. The low-temperature and low-pressure gas-phase refrigerant that has passed through the outdoor heat exchanger 4 is sucked into the compressor 2 via the four-way valve 3 and the accumulator 8, and is compressed again by the compressor 2 into a high-temperature and high-pressure gas-phase refrigerant and discharged into the circulation circuit 7.

[0020] In addition, in the present embodiment, the air conditioner 1 can be operated in either the cooling mode or the heating mode, but the air conditioner 1 may be, for example, a cooling-only machine or a heating-only machine that can be operated only in either the cooling mode or the heating mode.

[0021] Next, the specific configuration of the compressor 2 used in the air conditioner 1 will be described with reference to FIG. 2. FIG. 2 is a longitudinal sectional view schematically showing the configuration of the compressor 2. As shown in FIG. 2, the compressor 2 is a so-called vertical rotary compressor (rotary compressor), and mainly includes a sealed container 10, a compression mechanism portion 11, and an electric motor 12. In the following description, based on the relative positional relationship between the compression mechanism portion 11 and the electric motor 12 arranged along the central axis O1 of the sealed container 10 to be described later, the side where the compression mechanism portion 11 is located is the lower side, and the side where the electric motor 12 is located is the upper side. Also, the direction in which the central axis O1 extends is the axial direction, and the direction connecting the center and the circumference of a circle that is a cross section perpendicular to the axial direction is the radial direction.

[0022] The sealed container 10 has a cylindrical peripheral wall 10a and stands upright perpendicular to the installation surface. The installation surface is, for example, the bottom plate of the outdoor unit of the air conditioner 1. At the upper end of the sealed container 10, a refrigerant discharge pipe 10b is provided. The discharge pipe 10b forms a part of the circulation circuit 7 and is connected to the first port 3a of the four-way valve 3 via the circulation circuit 7. At the lower part of the sealed container 10, an oil sump portion 10c for storing lubricating oil I is provided.

[0023] The compression mechanism 11 compresses the refrigerant inside the sealed container 10 and discharges the compressed refrigerant into the sealed container 10. The compression mechanism 11 is housed in the lower part of the sealed container 10 so as to be immersed in the lubricating oil I. In the example shown in Figure 2, the compression mechanism 11 has a twin-cylinder structure and mainly comprises a first cylinder 13, a second cylinder 14, a rotating shaft 15, a first roller 16, and a second roller 17. Note that the number of cylinders in the compression mechanism is not limited to two, but may be one or three or more.

[0024] The first cylinder 13 is fixed to the inner surface of the peripheral wall 10a of the sealed container 10. The second cylinder 14 is fixed to the lower surface of the first cylinder 13 via a partition plate 18.

[0025] A first bearing 20 is fixed above the first cylinder 13. The first bearing 20 covers the inner diameter of the first cylinder 13 from above and protrudes upward toward the first cylinder 13. The space enclosed by the inner diameter of the first cylinder 13, the partition plate 18, and the first bearing 20 constitutes the first cylinder chamber 21. The partition plate 18 corresponds to a closing member that defines the lower surface of the first cylinder chamber 21, and the first bearing 20 corresponds to a closing member that defines the upper surface of the first cylinder chamber 21.

[0026] A second bearing 22 is fixed below the second cylinder 14. The second bearing 22 covers the inner diameter of the second cylinder 14 from below and protrudes downward toward the second cylinder 14. The space enclosed by the inner diameter of the second cylinder 14, the partition plate 18, and the second bearing 22 constitutes the second cylinder chamber 23. The partition plate 18 corresponds to a closing member that defines the upper surface of the second cylinder chamber 23, and the second bearing 22 corresponds to a closing member that defines the lower surface of the second cylinder chamber 23. The first cylinder chamber 21 and the second cylinder chamber 23 are arranged concentrically with the central axis O1 of the sealed container 10.

[0027] The first cylinder chamber 21 and the second cylinder chamber 23 are connected to the accumulator 8 via refrigerant suction pipes 25a and 25b. The suction pipes 25a and 25b constitute part of the circulation circuit 7. The gaseous refrigerant separated from the liquid phase refrigerant in the accumulator 8 is guided through these suction pipes 25a and 25b to the first cylinder chamber 21 and the second cylinder chamber 23.

[0028] The rotating shaft 15 has its axis coaxial with the central axis O1 of the sealed container 10 and penetrates the first cylinder chamber 21, the second cylinder chamber 23, and the partition plate 18. The rotating shaft 15 has a first journal portion 27a, a second journal portion 27b, and a pair of crankpin portions (eccentric portions) 28a, 28b. In other words, the rotating shaft 15 is configured as a crankshaft. The first journal portion 27a is rotatably supported by a first bearing 20. The second journal portion 27b is rotatably supported by a second bearing 22.

[0029] Furthermore, the rotating shaft 15 has an extension 27c that extends coaxially from the first journal portion 27a. The extension 27c passes through the first bearing 20 and protrudes above the compression mechanism portion 11. The rotor 33 of the electric motor 12, which will be described later, is fixed to the extension 27c by press-fitting or the like.

[0030] The eccentric portions 28a and 28b are located between the first journal portion 27a and the second journal portion 27b. The eccentric portions 28a and 28b are arranged, for example, with a 180-degree phase difference in the circumferential direction with respect to the central axis O1 of the sealed container 10, and their eccentricity with respect to the central axis O1 is the same. One eccentric portion (hereinafter referred to as the first eccentric portion) 28a is housed in the first cylinder chamber 21. The other eccentric portion (hereinafter referred to as the second eccentric portion) 28b is housed in the second cylinder chamber 23.

[0031] The ring-shaped first roller 16 is fitted to the outer circumferential surface of one eccentric portion 28a. When the rotating shaft 15 rotates, the first roller 16 rotates eccentrically within the first cylinder chamber 21, and a portion of the outer circumferential surface of the first roller 16 makes slidable line contact with the inner circumferential surface of the first cylinder chamber 21 via an oil film.

[0032] The ring-shaped second roller 17 is fitted onto the outer circumferential surface of the other eccentric portion 28b. When the rotating shaft 15 rotates, the second roller 17 rotates eccentrically within the second cylinder chamber 23, and a portion of the outer circumferential surface of the second roller 17 makes slidable line contact with the inner circumferential surface of the second cylinder chamber 23 via an oil film.

[0033] As shown in Figure 2, a vane 30 is positioned in the second cylinder 14. The vane 30 is supported by the second cylinder 14, for example, while being biased radially by a biasing means. The tip of the vane 30 is slidably pressed against the outer circumferential surface of the second roller 17. The vane 30 works in cooperation with the second roller 17 to divide the second cylinder chamber 23 into an intake region and a compression region, and moves in a direction that protrudes into the second cylinder chamber 23 or recedes from the second cylinder chamber 23 in accordance with the eccentric movement of the second roller 17. As the vane 30 moves back and forth relative to the second cylinder chamber 23 in this way, the volumes of the intake region and compression region of the second cylinder chamber 23 change, and the gaseous refrigerant drawn into the second cylinder chamber 23 from the suction pipe 25b is compressed.

[0034] Although not shown in the diagram, similar vanes 30 are also arranged in the first cylinder 13. Therefore, when the first roller 16 performs eccentric motion within the first cylinder chamber 21, the volumes of the intake and compression regions of the first cylinder chamber 21 change, and the gaseous refrigerant drawn into the first cylinder chamber 21 from the suction pipe 25a is compressed.

[0035] The high-temperature, high-pressure gaseous refrigerant compressed in the first cylinder chamber 21 and the second cylinder chamber 23 is discharged into the sealed container 10 via a discharge valve mechanism (not shown). The discharged gaseous refrigerant rises inside the sealed container 10. Furthermore, while the compression mechanism 11 is operating, the lubricating oil I stored in the oil reservoir 10c of the sealed container 10 is agitated. The agitated lubricating oil I becomes mist-like and rises inside the sealed container 10 towards the discharge pipe 10b, carried by the flow of the gaseous refrigerant. The sealed container 10 incorporates an oil separator 100 that separates the lubricating oil I contained in the gaseous refrigerant rising inside.

[0036] Figure 3 is a schematic diagram showing a part of the configuration of the electric motor 12 from above. As shown in Figures 2 and 3, the electric motor 12 is a drive device that drives the compression mechanism 11 and is housed in the sealed container 10 so as to be located between the compression mechanism 11 and the discharge pipe 10b. The electric motor 12 is a so-called inner rotor type electric motor and comprises a rotor 33 fitted onto a rotating shaft 15 and a stator 34 fixed to the inner surface of the peripheral wall 10a of the sealed container 10. Power is supplied to the electric motor 12 from the power source, causing the rotor 33 to rotate around the central axis O1 relative to the stator 34, and the rotating shaft 15 to rotate together with the rotor 33. The rotating shaft 15 is rotatably supported by two bearings 20 and 22.

[0037] The rotor 33 is equipped with a cylindrical core portion 35. The core portion 35 is constructed by stacking, for example, multiple annular electromagnetic steel sheets in the axial direction. The stacked electromagnetic steel sheets are integrated by means of crimping, for example, to form a single rotor 33. An insertion hole 36 is formed in the center of the core portion 35 into which an extension portion 27c of the rotating shaft 15 is inserted. The extension portion 27c of the rotating shaft 15 is coaxially fixed to the center of the core portion 35 facing the insertion hole 36 by means of press-fitting, for example.

[0038] The upper part of the extension 27c of the rotating shaft 15 is formed with a smaller diameter than the insertion hole 36 of the core part 35. The upper part of the extension 27c protrudes above the core part 35. A gap is secured between the outer circumferential surface of the upper part of the extension 27c and the inner circumferential surface of the center of the core part 35 facing the insertion hole 36, and the gap is continuous in the circumferential direction of the core part 35.

[0039] Multiple plate-shaped permanent magnets 38 are integrally embedded inside the core portion 35. The permanent magnets 38 are arranged to surround the insertion hole 36. Furthermore, multiple first passages 39 are formed near the inner circumference of the core portion 35. Each of the multiple first passages 39 penetrates the core portion 35 in the axial direction and is arranged at predetermined intervals in the circumferential direction of the core portion 35 so as to surround the insertion hole 36. Through these first passages 39, the gaseous refrigerant discharged from the compression mechanism 11 into the sealed container 10 is guided to the discharge pipe 10b.

[0040] The rotor 33 is equipped with a first balance weight 40 and a second balance weight 41. The first balance weight 40 and the second balance weight 41 are elements that counteract the rotational unbalance of the rotating shaft 15 caused by the eccentric motion of the first roller 16 and the second roller 17.

[0041] The first balance weight 40 consists of an annular first end plate 42 and a plurality of weight plates 43 stacked on the first end plate 42. The first end plate 42 is fixed to the upper end surface of the core portion 35. The second balance weight 41 consists of an annular second end plate 44 and a plurality of weight plates 45 stacked on the second end plate 44. The second end plate 44 is fixed to the lower end surface of the core portion 35.

[0042] The stator 34 has a stator core 34a and a coil (winding) 53. The stator core 34a is composed of a substantially cylindrical yoke 50 and a plurality of teeth (magnetic pole teeth) 51 that protrude radially inward from the yoke 50. The coil 53 is wound around each of the teeth 51 of the stator core 34a.

[0043] The stator core 34a is constructed in a roughly cylindrical shape by stacking, for example, multiple roughly fan-shaped electromagnetic steel sheets in the axial direction and arranging them in the circumferential direction, concentrically surrounding the rotor 33 over approximately the entire length of the rotor 33 in the axial direction. The stacked electromagnetic steel sheets are integrated by, for example, crimping, and adjacent fan-shaped electromagnetic steel sheets in the circumferential direction are fixed together by welding or the like. The stator core 34a is positioned and fixed to the circumferential wall 10a of the sealed container 10 by shrink-fitting. Each of the multiple teeth 51 is arranged at a predetermined interval in the circumferential direction of the yoke 50 (hereinafter simply referred to as the circumferential direction), and protrudes from the inner circumferential surface of the yoke 50 toward the outer circumferential surface of the rotor 33 over the entire length of the yoke 50 in the axial direction. The axial direction of the yoke 50 is the direction in which the central axis of the yoke 50 (same as the central axis line O1) extends. A narrow air gap G is formed between the tip surface 51c of the teeth 51 and the outer circumferential surface of the rotor 33. The number of teeth 51 can be arbitrarily set to correspond to the number of magnetic poles. In the example shown in Figure 3, nine teeth 51 are provided on the stator core 34a.

[0044] Furthermore, as shown in Figure 2, the stator core 43a is equipped with insulating components 55 and 56. The insulating components 55 and 56 are interposed between the yoke 50 and each of the multiple teeth 51 of the stator core 34a and the coil (winding) 53 to provide insulation. That is, the coil 53 is wound around the teeth 51 of the stator core 34a via the insulating components 55. The insulating component 55 is made of an insulator, such as a synthetic resin material having electrical insulating properties, such as polybutylene terephthalate resin, liquid crystal polymer resin, or polyphenylene sulfide resin. In the illustrated example, the insulating components 55 and 56 are arranged in pairs at both ends of the stator core 34a in the axial direction. One insulating component 55 is positioned concentrically with the stator core 34a at the upper end of the stator core 34a. The other insulating component 56 is positioned concentrically with the stator core 34a at the lower end of the stator core 34a.

[0045] As shown in Figure 3, in this embodiment, the stator core 34a is constructed by assembling together divided core components (hereinafter referred to as divided cores) 34b, which are core components divided in the circumferential direction. However, the stator core 34a does not have to be constructed in such a divided manner. For example, the stator core 34a is divided according to the teeth 51 it has. In the illustrated example, the stator core 34a is divided into nine divided cores 34b. These divided cores 34b are arranged in a line in the circumferential direction, and together they constitute a substantially cylindrical stator core 34a. Two circumferentially adjacent divided cores 34b are arranged in a line in the circumferential direction with their side portions 50e and 50f in contact with each other. Figure 3 shows an example of a state in which three divided cores 34b within a stator core 34a, which is constructed in a substantially cylindrical shape as a whole, are arranged in a line in the circumferential direction.

[0046] As shown in Figure 3, each of the multiple segmented cores 34b constitutes a portion of the yoke 50 in the stator core 34a and a single tooth 51 protruding from the portion of the yoke 50. In other words, the stator core 34a is composed of multiple segmented cores 34b, each containing a single tooth 51 and a portion of the yoke 50 from which the single tooth 51 protrudes.

[0047] The portion of the yoke 50 includes an outer circumferential surface portion 50a that forms the outer surface of the stator core 34a, a flat inner circumferential surface portion 50b facing the slot 52, flat end surfaces 50c and 50d that connect to the outer circumferential surface portion 50a and the inner circumferential surface portion 50b at both ends in the axial direction, and flat side surfaces 50e and 50f that are contact points with adjacent segmented cores 34b. Adjacent segmented cores 34b in the circumferential direction are arranged so that the side surface portion 50e of one segmented core 34b is in contact with the side surface portion 50f of the other segmented core 34b.

[0048] The teeth 51 consist of a pair of side surfaces 51a, 51b extending radially toward the rotor 33 from the inner circumferential surface 50b of the yoke 50 in the divided core 34b, a protruding end surface 51c connecting the inner diameter edges of these side surfaces 51a, 51b, and flat end surfaces 51d, 51e connecting to the side surfaces 51a, 51b and the protruding end surface 51c at both ends in the axial direction. The side surfaces 51a, 51b each project in the circumferential direction from the side surfaces 51a, 51b and connect to the protruding end surface 51c and the end surfaces 51d, 51e, and have a pair of projections 51f, 51f that extend continuously along the entire axial length of the divided core 34b. The protruding end surface 51c is located at the inner diameter end of the teeth 51 and faces the outer circumferential surface of the core 35 of the rotor 33 with a narrow air gap G between them. The end face portion 51d is flush with and continuous with the end face portion 50c of the yoke 50, and the end face portion 51e is flush with and continuous with the end face portion 50d of the yoke 50. These end faces 50c, 50d and 51d, 51e constitute the end faces at both axial ends of the divided core 34b, and ultimately the stator core 34a.

[0049] As shown in Figure 3, in the stator core 34a, slots 52 are formed between adjacent teeth 51 in the circumferential direction, or in other words, on both sides of the teeth 51 in the divided core 34b in the circumferential direction. The slots 52 are spaces for accommodating the coils 53 wound around the teeth 51. The slots 52 are spaced apart in the circumferential direction of the yoke 50 and are continuous along the entire axial length of the yoke 50.

[0050] Furthermore, the yoke 50 has a plurality of second passages (hereinafter referred to as grooves) 54. Each of the plurality of grooves 54 is a recess extending along the axial direction provided on the outer peripheral surface 50a of the yoke 50, and is arranged at predetermined intervals in the circumferential direction of the yoke 50. That is, each of the plurality of grooves 54 is configured by recessing the outer peripheral surface 50a of the yoke 50 continuously in the axial direction. The outer peripheral surface 50a of the yoke 50 is, for example, the fitting surface with the peripheral wall 10a when the stator core 34a is shrink-fitted to the peripheral wall 10a of the sealed container 10, and is in close contact with the peripheral wall 10a. As a result, a plurality of spaces are created between the yoke 50 and the peripheral wall 10a of the sealed container 10 that communicate in the axial direction at positions corresponding to the grooves 54. Therefore, these plurality of spaces, i.e., grooves 54, guide the gaseous refrigerant discharged from the compression mechanism 11 into the interior of the sealed container 10 through the grooves 54 to the discharge pipe 10b.

[0051] In addition, in this embodiment, the yoke 50 has a plurality of holes 60 that penetrate the yoke 50 continuously in the axial direction. The holes 60 penetrate the yoke 50 continuously in the axial direction from end face 50c to end face 50d. As a result, the yoke 50 has a plurality of spaces that communicate in the axial direction at positions corresponding to the holes 60, from the end face 50d side to the end face 50c side of the yoke 50. Therefore, these plurality of spaces, i.e., the holes 60, guide the gaseous refrigerant discharged from the compression mechanism 11 into the sealed container 10 through the holes 60 to the discharge pipe 10b.

[0052] As described above, in this embodiment, the stator core 34a is divided into a plurality (nine, for example) of segmented cores 34b. The grooves 54 and holes 60 are equally arranged in each of these segmented cores 34b. Figure 4 is a schematic cross-sectional view of the segmented cores 34b perpendicular to the axial direction, showing the configuration of the segmented cores 34b.

[0053] As shown in Figures 3 and 4, each of the multiple segmented cores 34b has one groove 54 and two holes 60. In the axial perpendicular cross-section of the segmented core 34b as shown in Figure 4, the grooves 54 are positioned on the centerline L51 (the dashed line shown in Figure 4) of the teeth 51 of the segmented core 34b. The centerline L51 of the teeth 51 is an imaginary line that divides the teeth 51 approximately in the circumferential direction. That is, each of the multiple teeth 51 has a form that is approximately symmetrical with respect to the centerline L51.

[0054] In the axial vertical cross-section of the segmented core 34b as shown in Figure 4, the inner circumferential surface portion 50b of the yoke 50 is continuous with respect to the center line L51 of the teeth 51, approximately perpendicular to each other. In the illustrated example, the side portions 51a and 51b of the teeth 51 are approximately parallel to the center line L51 of the teeth 51, and these side portions 51a and 51b are connected to the inner circumferential surface portion 50b of the yoke 50 approximately perpendicular to each other.

[0055] As shown in Figures 3 and 4, each of the multiple grooves 54 has a groove bottom 54a that is continuous in a flat manner in the axial direction and a pair of groove walls 54b, 54c that are inclined and rise from the edge of the groove bottom 54a and connect to the outer circumferential surface 50a of the yoke 50. In the axial vertical cross-section of the divided core 34b as shown in Figure 4, the groove bottom 54a is continuous substantially perpendicular to the center line L51 of the teeth 51, and the groove walls 54b, 54c are flat inclined surfaces that connect the groove bottom 54a and the outer circumferential surface 50a. In the illustrated example, the groove 54 has a substantially trapezoidal (bathtub-shaped) contour defined by the groove bottom 54a and the groove walls 54b, 54c, but its contour is not limited to this. The contour of the groove may be, for example, substantially rectangular, substantially V-shaped, or a stepped shape with a key.

[0056] In the axial vertical cross-section of the divided core 34b shown in Figure 4, the groove 54 is symmetrical with respect to the center line L51. In other words, the groove bottom 54a is symmetrical with respect to the center line L51, and the groove walls 54b and 54c are arranged in pairs on either side of the center line L51 so as to be symmetrical with respect to the center line L51.

[0057] As shown in Figures 3 and 4, each of the multiple holes 60 has a triangular opening and three surfaces (first surface 60a, second surface 60b, and third surface 60c) surrounding the opening. However, the shape of the opening of the hole 60 is not limited to such a triangular shape and may be arbitrary. In the axial vertical cross-section of the divided core 34b as shown in Figure 4, the first surface 60a is a flat surface substantially parallel to the inner circumferential surface 50b of the yoke 50 and the groove bottom 54a of the groove 54, the second surface 60b is a flat surface substantially parallel to the outer circumferential surface 50a of the yoke 50, and the third surface 60c is a flat surface substantially parallel to the groove wall 54b (or groove wall 54c) of the groove 54. In other words, the first surface portion 60a is continuous with respect to the center line L51 and the side portions 51a and 51b of the teeth 51, respectively, in a manner that is approximately perpendicular to them.

[0058] As shown in Figure 4, partition walls 57b and 57c exist between the opening edge of the hole 60 and the outer circumferential surface 50a of the yoke 50. In the illustrated example, partition wall 57b separates the second surface 60b of the hole 60 from the outer circumferential surface 50a of the yoke 50, and partition wall 57c separates the third surface 60c of the hole 60 from the groove walls 54b and 54c of the groove 54 of the yoke 50. Partition walls 57b and 57c are connected at positions corresponding to the connection points between the second surface 60b and the third surface 60c of the hole 60.

[0059] In the axial vertical cross-section of the divided core 34b shown in Figure 4, the holes 60 are arranged in pairs on both sides of the center line L51 so as to be symmetrical with respect to the center line L51. That is, in the divided core 34b, two identical holes 60 (61, 62) are each positioned symmetrically with respect to the center line L51. These holes 61 and 62 are arranged as follows.

[0060] In the axial vertical cross-section of the divided core 34b as shown in Figure 4, the holes 61 and 62 are positioned such that the distance D41 is greater than or equal to the distance D42. The distance D41 is the shortest distance between the opening edge of the holes 61 and 62 of the divided core 34b and the inner circumferential surface portion 50b of the yoke 50 in the divided core 34b (the distance shown as D41 in Figure 4). In the illustrated example, the distance D41 is the shortest distance between the first surface portion 60a of the holes 61 and 62 and the inner circumferential surface portion 50b. The distance D42 is the shortest distance between the groove bottom portion 54a of the groove portion 54 in the divided core 34b and the inner circumferential surface portion 50b of the yoke 50 in the divided core 34b (the distance shown as D42 in Figure 4).

[0061] In other words, in the axial vertical cross-section of the divided core 34b as shown in Figure 4, the opening edges of the holes 61 and 62 and the groove bottom 54a of the groove 54 lie on the same vertical line with respect to the centerline L51 of the teeth 51, or the opening edges of the holes 61 and 62 lie closer to the outer circumferential surface 50a of the yoke 50 than the said vertical line. In the illustrated example, the first surface 60a of the holes 61 and 62 and the groove bottom 54a of the groove 54 lie on approximately the same vertical line with respect to the centerline L51 of the teeth 51.

[0062] Furthermore, in the axial vertical cross-section of the divided core 34b as shown in Figure 4, the holes 61 and 62 are positioned such that the distance D43 is shorter than the distance D44. Distance D43 is the shortest distance between the opening edge of the holes 61 and 62 of the divided core 34b and the groove wall portions 54b and 54c of the groove portion 54 in the divided core 34b (the distance shown as D43 in Figure 4). In the illustrated example, distance D43 is the shortest distance between the third surface portion 60c of the holes 61 and 62 and the groove wall portions 54b and 54c. Distance D44 is the shortest distance between the opening edge of the holes 61 and 62 of the divided core 34b and the side portions 50e and 50f of the yoke 50 in the divided core 34b (the distance shown as D44 in Figure 4). In the illustrated example, distance D44 is defined as the shortest distance between the connection point between the first surface 60a and the second surface 60b of the holes 61 and 62 and the side surfaces 50e and 50f. That is, in the axial vertical cross-section of the divided core 34b as shown in Figure 4, the opening edges of the holes 61 and 62 are located closer to the groove walls 54b and 54c (in other words, the partition wall 57c) of the groove 54 in the divided core 34b than to the side surfaces 50e and 50f of the yoke 50 in the divided core 34b.

[0063] Here, the angle formed by the first surface 60a and the second surface 60b is acute. Also, the angle formed by the second surface 60b and the third surface 60c is obtuse. As a result, the shape of the hole 60 is formed into a flattened shape that is elongated in the circumferential direction.

[0064] Thus, according to this embodiment, the stator 34 of the electric motor 12 has a plurality of grooves 54 and a plurality of holes 60 in the yoke 50. That is, for example in the compressor 2, the gaseous refrigerant discharged from the compression mechanism 11 into the sealed container 10 can be guided through these grooves 54 and holes 60 to the discharge pipe 10b via a plurality of paths.

[0065] In other words, by providing holes 60 in addition to grooves 54 in the yoke 50, the path for guiding the refrigerant can be expanded by the amount of the holes 60. This makes it possible to increase the cooling efficiency of the electric motor 12 and achieve higher output compared to the case where only grooves 54 are provided. In other words, it is possible to increase the cooling efficiency of the electric motor 12 without expanding the grooves 54.

[0066] As described above, the groove 54 is a recess extending axially on the outer circumferential surface 50a of the yoke 50, and the outer circumferential surface 50a of the yoke 50 is the fitting surface with respect to the peripheral wall 10a when, for example, the stator core 34a is shrink-fitted to the peripheral wall 10a of the sealed container 10. Therefore, expanding the groove 54 on the outer circumferential surface 50a reduces the fitting surface with respect to the peripheral wall 10a of the sealed container 10. Accordingly, according to this embodiment, the cooling efficiency of the electric motor 12 can be increased without reducing the fitting surface with respect to the peripheral wall 10a by expanding the groove 54. In other words, the cooling efficiency of the electric motor 12 can be increased while maintaining the holding force of the stator core 34a to the sealed container 10 without reducing it when the stator core 34a is shrink-fitted to the sealed container 10.

[0067] In addition, the yoke 50 has a hole 60, which allows the stator core 34a to absorb the stress (shrink-fit stress) generated in the stator core 34a when it is shrink-fitted into the sealed container 10, thereby mitigating the stress. This reduces the energy loss (iron loss) generated in the stator core 34a. Furthermore, the hole 60 suppresses deformation of the stator core 34a and contributes to a damping effect against deformation, thereby reducing noise during operation of the electric motor 12.

[0068] Furthermore, in the axial vertical cross-section of the divided core 34b as shown in Figure 4, the holes 60 are positioned such that the distance D41 is greater than or equal to the distance D42, and the distance D43 is shorter than the distance D44. That is, in such a vertical cross-section, the opening edge of the hole 60 and the groove bottom 54a of the groove 54 lie on the same vertical line with respect to the center line L51 of the teeth 51 in the divided core 34b, or the opening edge of the hole 60 lies closer to the outer peripheral surface 50a of the yoke 50 in the divided core 34b than the vertical line. Also, in such a vertical cross-section, the opening edge of the hole 60 lies closer to the groove walls 54b and 54c of the groove 54 in the divided core 34b than to the side surfaces 50e and 50f of the yoke 50 in the divided core 34b.

[0069] This makes it easier to remove the holes 60 from the magnetic flux path generated by the conduction of the coil 53, thereby suppressing the holes 60 from becoming magnetic resistance on the magnetic flux path. Therefore, it is possible to prevent an increase in magnetic resistance caused by the holes 60.

[0070] Here, because the yoke 50 has holes 60, compared to the comparative example where there are no holes 60, for example, the induced voltage and torque in the electric motor 12 are reduced, while torque ripple and iron loss increase. On the other hand, in the vertical axial cross-section of the divided core 34b as shown in Figure 4, by arranging the holes 60 at positions where the distance D41 is greater than or equal to the distance D42, and at positions where the distance D43 is shorter than the distance D44, the reduction in induced voltage and torque in the electric motor 12 can be minimized compared to the comparative example, and the increase in torque ripple and iron loss can be minimized, while the cooling efficiency of the electric motor 12 can be increased compared to the comparative example.

[0071] In this embodiment, low-pressure refrigerants such as R290, R454B, and R454C are used as the refrigerant in the compressor 2. In refrigeration cycles using these refrigerants, the difference in refrigeration capacity for the same pressure loss is greater compared to cases where refrigerants such as R32 or R410A are used, and there is a risk of a decrease in refrigeration capacity. Therefore, in order to suppress the decrease in refrigeration capacity and maintain equivalent refrigeration capacity when low-pressure refrigerants such as R290, R454B, and R454C are used, it is necessary to increase the compression volume of the compressor 2 compared to cases where refrigerants such as R32 or R410A are used. When the compression volume of the compressor 2 is increased, the flow velocity of the refrigerant tends to increase, leading to a deterioration of pressure loss.

[0072] As described above, according to this embodiment, by providing holes 60 in addition to grooves 54 in the yoke 50, the path for guiding the refrigerant can be expanded by the amount of the holes 60. Therefore, even when low-pressure refrigerants such as R290, R454B, or R454C are used as the refrigerant for the compressor 2, deterioration of pressure loss can be suppressed, and the same refrigeration capacity as when refrigerants such as R32 or R410A are used can be maintained.

[0073] Furthermore, by making the shape of the hole 60 flat, the surface area of ​​the hole 60 can be increased even in a narrow space, thereby improving the cooling capacity of the refrigerant that conducts through it. In particular, by making the angle on the circumferential side of the yoke 50 acute and the angle located on the radial outer side obtuse, it is possible to secure the necessary refrigerant path and surface area even in a narrow space while minimizing the increase in torque ripple and iron loss.

[0074] (Second embodiment) As shown in Figure 4, in the divided core 34b of the stator core 34a according to the first embodiment, the groove portion 54 is symmetrical with respect to the center line L51. That is, the groove bottom portion 54a is symmetrical with respect to the center line L51, and the groove wall portions 54b and 54c are arranged in pairs on both sides of the center line L51 so as to be symmetrical with respect to the center line L51. In addition, the holes 60 are arranged in pairs on both sides of the center line L51 so as to be symmetrical with respect to the center line L51.

[0075] However, in the vertical cross-section of the divided core 34b in the axial direction as shown in Figure 4, the grooves 54 and holes 60 are not limited to the form shown in the illustration. Hereinafter, an example of grooves and holes different from the form shown in Figure 4 will be described as a second embodiment. Figure 5 is a vertical cross-sectional view of the divided core 34b in the axial direction, schematically showing the configuration of the divided core 34b according to the second embodiment. In the second embodiment, the configuration other than the grooves 70 is the same as in the first embodiment shown in Figures 1 to 4. Therefore, the configuration other than the grooves 70 in the second embodiment shown in Figure 5 will not be described, with reference to Figures 1 to 4 as appropriate.

[0076] As shown in Figure 5, the groove 70 according to this embodiment is expanded to a different form (hereinafter referred to as the second groove form) from the form of the groove 54 according to the first embodiment shown in Figure 4 (hereinafter referred to as the first groove form). That is, the second groove form, which is the form of the groove 70, is expanded compared to the first groove form, which is the form of the groove 54.

[0077] The groove 70 has a configuration in which the groove 54 and hole 61 of the first embodiment shown in Figure 4 are continuously connected. As shown in Figure 5, the groove 70 of this embodiment has a configuration in which the groove 54 and the region corresponding to hole 61, which is one of the pair of holes 61 and 62 shown in Figure 4 that are arranged in pairs on both sides of the center line L51 in the axial vertical cross section of the divided core 34b are continuously connected.

[0078] In other words, in this embodiment shown in Figure 5, there is no partition wall 57c separating the third surface 60c of the hole 61 shown in Figure 4 from the groove wall 54b of the groove 54, and only a portion 58b corresponding to the partition wall 57b separating the second surface 60b of the hole 61 from the outer surface 50a (hereinafter referred to as the partition wall equivalent portion) exists. The inner surface 70b of the partition wall equivalent portion 58b (the surface opposite to the outer surface 50a) is approximately equivalent to the second surface 60b of the hole 61 shown in Figure 4. Furthermore, the groove bottom 70a of the groove 70 shown in Figure 5 is approximately equivalent to a surface that is flush and continuous with the portion corresponding to the groove bottom 54a of the groove 54 shown in Figure 4 and the first surface 60a of the hole 61. The inner surface portion 70b of the partition wall portion 58b corresponds to the groove wall portion opposite to the groove wall portion 54c that is continuous with the groove bottom portion 70a of the groove portion 70.

[0079] In contrast, in the present embodiment shown in Figure 5, the hole 62 shown in Figure 4, the partition wall 57b separating the second surface 60b and the outer peripheral surface 50a of the hole 62, and the partition wall 57c separating the third surface 60c of the hole 62 and the groove wall 54b of the groove 54 are all still present.

[0080] Thus, the groove 70 corresponds to the form in which the partition wall 57c between the groove 54 and the hole 61 in the first embodiment is removed. Therefore, the groove 70 is extended by the area corresponding to the hole 61 and the partition wall 57c compared to the groove 54 in the first embodiment. The shortest distance (distance shown as D44 in Figure 4) between the opening edge of the hole 61 of the divided core 34b shown in Figure 4 and the side surface 50e of the yoke 50 in the divided core 34b corresponds to the distance D54 shown in Figure 5. Distance D54 is the shortest distance between the edge of the groove 70 of the divided core 34b and the side surface 50e of the yoke 50 in the divided core 34b. In the illustrated example, distance D54 is the shortest distance between the connection position between the groove bottom 70a of the groove 70 and the inner circumferential surface 70b of the partition wall equivalent portion 58b and the side surface 50e, and coincides with distance D44.

[0081] Unlike the illustrated example, the second groove shape, which is the shape of the groove portion 70, may be extended only to the area corresponding to the hole portion 62 and the partition wall portion 57c between the hole portion 62 and the groove portion 54 in the first embodiment. If the partition wall portion 57c between one of the holes 61, 62 shown in Figure 4 and the groove portion 54 is removed, the second groove shape may be made to be continuously connected to, for example, the area corresponding to the hole portion 60 located on the leading side (front side) in the rotation direction of the rotating shaft of the electric motor 12 and the rotor 33 among the pair of holes 60 arranged. In this configuration, in the example shown in Figure 5, the direction of rotation will be clockwise. In this case, the hole portion 62 located on the trailing side (rear side) in this direction of rotation may be left as a through hole of the yoke 50.

[0082] Furthermore, the second groove configuration may be one in which both of the partition walls 57c between the holes 61 and 62 and the groove 54, as shown in Figure 4, are removed. In this case, the portions corresponding to the two partition walls 57b remain.

[0083] Even in the second groove configuration, the partition portion 57b and the partition-equivalent portion 58b are present. The partition portion 57b and the partition-equivalent portion 58b include, for example, the outer peripheral surface portion 50a of the yoke 50, which is the fitting surface portion to the peripheral wall 10a when the stator core 34a is shrink-fitted to the peripheral wall 10a of the sealed container 10. Therefore, according to this embodiment, it is not necessary to reduce the fitting surface portion to the peripheral wall 10a. As a result, similar to the first embodiment, the cooling efficiency of the electric motor 12 can be increased while maintaining the retaining force of the stator core 34a to the sealed container 10 without reducing it when the stator core 34a is shrink-fitted to the sealed container 10.

[0084] Although several embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0085] 1...Air conditioner, 2...Compressor, 3...Four-way valve, 4...Outdoor heat exchanger, 401...Outdoor fan, 5...Expansion device, 6...Indoor heat exchanger, 601...Indoor fan, 7...Circulation circuit, 10...Sealed container, 11...Compression mechanism, 12...Electric motor, 15...Rotating shaft, 33...Rotor, 34...Stator, 34a...Stator core, 34b...Split core, 50...Yoke, 50a...Outer surface, 50b...Inner surface, 50c, 50d...End surface, 50e, 50f...Side surface, 51...Teeth, 51a, 51b...Side surface, 51c...Protruding end surface, 51d, 51e...End surface, 51f...Protrusion, 52...Slot, 53...Coil, 54, 70...Second passage (groove), 54 a, 70a... Groove bottom, 54b, 54c... Groove wall, 55, 56... Insulating parts, 57b, 57c... Partition wall, 58b... Partition wall equivalent, 60, 61, 62... Hole, 60a... First surface, 60b... Second surface, 60c... Third surface, 70b... Surface (groove wall), 100... Oil separator, D41... Shortest distance between the opening edge of the hole and the inner surface of the yoke, D42... Shortest distance between the groove bottom of the groove and the inner surface of the yoke, D43... Shortest distance between the opening edge of the hole and the groove bottom of the groove, D44... Shortest distance between the opening edge of the hole and the side surface of the yoke, D54... Shortest distance between the edge of the groove and the side surface of the yoke, L51... Centerline of the teeth, O1... Center axis of the sealed container.

Claims

1. It comprises a cylindrical stator core that is fixed to a rotating shaft and surrounds a rotor that rotates the rotating shaft, and a winding wound around the stator core, The stator core comprises a cylindrical yoke concentrically surrounding the rotor, a plurality of teeth projecting radially inward from the yoke and spaced apart circumferentially from the yoke, and a plurality of slots formed between adjacent teeth in the circumferential direction for housing the windings. The yoke has a groove portion that is recessed in the outer circumferential surface of the yoke, which is continuous in the axial direction in which the rotation shaft extends, allowing the coolant to pass through, and a hole portion that penetrates the yoke, which is continuous in the axial direction. In a cross-section perpendicular to the stator core with respect to the axial direction, the groove is positioned on a virtual line that substantially bisects the teeth in the circumferential direction, and the hole is positioned such that the shortest distance between the opening edge of the hole and the inner circumferential surface of the yoke is greater than or equal to the shortest distance between the groove and the inner circumferential surface of the yoke. Stator of an electric motor.

2. The stator core is divided into a plurality of segmented cores, each including one tooth and a portion of the yoke from which the one tooth protrudes. Each of the plurality of divided cores has a contact surface portion with other divided cores adjacent to it in the circumferential direction. In the aforementioned vertical cross-section, the shortest distance between the opening edge of the hole in the divided core and the contact surface of the divided core is shorter than the shortest distance between the opening edge of the hole and the contact surface of the divided core. A stator for an electric motor as described in claim 1.

3. In the aforementioned vertical cross-section, the groove portion is symmetrical with respect to the imaginary line, and the holes are arranged in pairs on both sides of the imaginary line so as to be symmetrical with respect to the imaginary line. A stator for an electric motor as described in claim 1.

4. In the aforementioned vertical cross-section, the groove is extended to a second groove shape that is different from the first groove shape which is symmetrical with respect to the imaginary line, and the second groove shape is connected in a continuous manner to the region corresponding to one of the paired holes. Stator of an electric motor according to claim 3.

5. In the aforementioned vertical cross-section, the second groove configuration is continuous with the region corresponding to the hole located on the leading side in the rotational direction of the rotation axis, among the pair of holes arranged in the same manner. Stator of an electric motor according to claim 4.

6. The groove portion has a groove bottom that is continuous in the axial direction, In the vertical cross-section, the inner circumferential surface of the yoke and the groove bottom of the groove are continuous perpendicularly to the imaginary line. A stator for an electric motor as described in claim 1.

7. The rotor and, A stator according to any one of claims 1 to 6, comprising Electric motor.

8. A cylindrical airtight container, A compression mechanism that compresses the refrigerant inside the sealed container and discharges the compressed refrigerant into the sealed container, The electric motor according to claim 7, which is housed in the sealed container and drives the compression mechanism, is provided. Compressor.

9. The refrigerant is one of R290, R454B, or R454C. The compressor according to claim 8.

10. The refrigerant circulates through a circulation circuit connected to a condenser, an expansion device, and an evaporator, The compressor according to claim 8, which is connected to the circulation circuit between the condenser and the evaporator, comprises Refrigeration cycle device.

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