Electric motor, compressor, and device

Abstract

Provided is an electric motor 14 capable of maintaining lamination strength at a level at which stator core sheets can maintain a correct lamination state, and capable of reducing iron loss to achieve high efficiency, and also provided are a compressor 10 using the electric motor 14 and a device using the compressor 10, wherein said electric motor 14 is obtained in such a way that: a plurality of split cores 30A, split corresponding to each of a plurality of tooth portions 32, are arranged in an annular shape; a rotor 20 is disposed inside the inner periphery of the split cores 30A; the split cores 30A are each formed by laminating a plurality of the stator core sheets and each have an arc-shaped yoke portion 31 formed about a rotary shaft 4 of the rotor 20, a tooth portion 32 extending from the yoke portion 31 toward the rotor 20, and an umbrella portion 33 formed at the tip of the tooth portion 32; a slot 34 is formed between adjacent split cores 30A; a winding is wound around each tooth portion 32; welding portions 36 for fixing the plurality of stator core sheets are not positioned in the tooth portions 32 or the umbrella portions 33, but are positioned in back yoke surfaces of the yoke portions 31; and two or more of the welding portions 36 are provided.

Description

Electric motors, compressors, and equipment

[0001] The present invention relates to an electric motor using a split core, a compressor using this electric motor, and equipment using this compressor.

[0002] Using a split core as a stator allows for more windings in an electric motor, which reduces copper loss and improves efficiency. A stator is constructed by stacking multiple stator core sheets, but a stator core layer is required to stack the stator core sheets. The stator core layer is a structure for intertwining the upper and lower stator core sheets, and is constructed by forming irregularities on a portion of the stator core sheet. However, the stator core layer generates iron loss, and because split cores require more stator core layers than integrated cores, increasing the number of stator core layers increases iron loss. Iron loss due to the stator core layer can be reduced by forming the stator core layer on the yoke portion rather than the teeth portion. However, forming the stator core layer only on the yoke portion and not on the teeth portion presents a problem. Specifically, the stator core layer used to intertwine the upper and lower stator core sheets does not completely seal the upper and lower stator core sheets, even when pressed after stacking the stator core sheets, resulting in tiny gaps. Therefore, if the lamination is formed only on the yoke portion, even if the stator core sheets are pressed after lamination, the lamination thickness of the yoke portion will be greater than that of the teeth portion. Furthermore, the lamination thickness of the yoke portion being greater than that of the teeth portion makes it difficult to accurately assemble the split cores in an annular arrangement. Forcing the split cores into an annular arrangement leaves residual stress, which increases iron loss. On the other hand, instead of lamination, the shape of the split cores can be maintained by welding the stacked stator core sheets. However, welding also affects the magnetic flux and increases iron loss. Therefore, iron loss due to welds must be suppressed. After reexamining the lamination strength required to maintain the shape of the stacked stator core sheets, the inventors discovered that it is sufficient to achieve a lamination strength that allows the stator sheets to maintain the correct lamination state until the winding is completed around the split core. Patent Documents 1 and 2 propose split cores in which stacked stator core sheets are fixed by welding.

[0003] Japanese Patent Application Laid-Open No. 7-298522 International Publication No. 2017 / 090137

[0004] However, in Patent Documents 1 and 2, the welding positions are the teeth and the umbrella portions formed at the tips of the teeth, which have a large effect on the magnetic flux at these positions, resulting in increased iron loss.

[0005] The present invention aims to provide an electric motor that can achieve high efficiency by maintaining a level of laminate strength that allows the stator core sheets to maintain the correct laminated state and reducing iron loss, a compressor using this electric motor, and equipment using this compressor.

[0006] The electric motor (14) of the present invention described in claim 1 has a plurality of split cores (30A) divided into each tooth portion (32) and arranged in a circular ring shape, a rotor (20) arranged on the inner circumference of the plurality of split cores (30A) arranged in a circular ring shape, the split cores (30A) being constructed by stacking a plurality of stator core sheets, the split cores (30A) having an arc-shaped yoke portion (31) centered on the rotation axis (4) of the rotor (20), the teeth portions (32) extending from the yoke portion (31) toward the rotor (20), and umbrella portions (33) formed at the tips of the teeth portions (32), slots (34) being formed between adjacent split cores (30A), and windings being wound around the teeth portions (32), and is characterized in that the position of the welds (36) that secure the plurality of stator core sheets is not on the teeth portions (32) and the umbrella portions (33), but on the back yoke surface of the yoke portion (31), and there are two or more welds (36). The present invention of claim 2 is the electric motor 14 of claim 1, characterized in that the welded portion 36 is continuous from the stator core sheet arranged on one end surface of the split core 30A to the stator core sheet arranged on the other end surface of the split core 30A. The present invention of claim 3 is the electric motor 14 of claim 1, characterized in that each of the welded portions 36 has a weld depth of 0.4 mm or less and a weld width of 0.8 mm or more. The present invention of claim 4 is the electric motor 14 of claim 1, characterized in that no karamasa is formed on the stator core sheet. The present invention of claim 5 is the electric motor 14 of claim 1, characterized in that a groove 35 is formed in the back yoke surface from the stator core sheet arranged on one end surface of the split core 30A to the stator core sheet arranged on the other end surface of the split core 30A, and the welded portion 36 is located in the groove 35. The present invention according to claim 6 is characterized in that in the electric motor 14 according to claim 5, the welded portion 36 is not positioned at the narrowest portion B where the distance from the slot 34 is narrowest.The present invention of claim 7 is characterized in that, in the electric motor 14 of claim 6, when the inner surface circumferential length of the groove 35 is L and the prohibited circumferential length centered on the narrowest portion B is M, the prohibited circumferential length M is determined as M = 0.005 × L, and the welded portion 36 is not positioned within the range of the prohibited circumferential length M. The present invention of claim 8 is characterized in that the electric motor 14 of claim 1, wherein an undercut 37 is formed in the back yoke surface, the undercut 37 serves as the welded portion 36, and the welded portion 36 does not protrude from the back yoke surface. The compressor 10 of the present invention of claim 9 is a compressor 10 using the electric motor 14 of any one of claims 1 to 8, wherein the electric motor 14 and the compression mechanism 13 are disposed in a sealed container 1, and the stator 30, in which the plurality of split cores 30A are arranged in an annular shape, is fixed to the sealed container 1 by the back yoke surface. The equipment of the present invention described in claim 10 is an equipment using the compressor 10 described in claim 9, characterized in that the compressor 10, the condenser 17, the pressure reducing device 18, and the evaporator 19 are connected in a ring shape by piping.

[0007] According to the present invention, by positioning the welds on the back yoke surface of the yoke rather than on the teeth and umbrella portions, iron loss can be reduced, and by providing two or more welds, the stator core sheets can be maintained in a correct stacked state. Furthermore, by positioning multiple welds only on the back yoke surface of the yoke, the laminated strength is not too strong, allowing the split cores to be combined in a smooth annular shape, and iron loss due to residual stress can be reduced.

[0008] 7A and 7B are schematic diagrams of a compressor using an electric motor according to an embodiment of the present invention, and a refrigeration system using this compressor; a perspective view of a main part of the electric motor according to this embodiment; a structural diagram showing a divided core according to this embodiment; an explanatory diagram showing the position of a welded portion relative to a groove; an explanatory diagram showing a range in which a welded portion is not positioned relative to a groove; an explanatory diagram showing the position of a welded portion relative to a back yoke surface other than the groove; an explanatory diagram showing the position of a welded portion relative to a groove with a shape different from that of FIG. 4; an explanatory diagram showing a range in which a welded portion is not positioned relative to a groove with a shape shown in FIG. 7; an explanatory diagram showing the position of a welded portion relative to a back yoke surface other than the groove; a graph showing the relationship between welding and iron loss; and a structural diagram of a compressor showing another embodiment using a scroll compressor, and a refrigeration system using this compressor.

[0009] In the electric motor according to the first embodiment of the present invention, the welds that secure the multiple stator core sheets are located on the back yoke surface of the yoke, rather than on the teeth and umbrella portions, and there are two or more welds. According to this embodiment, by locating the welds on the back yoke surface of the yoke, rather than on the teeth and umbrella portions, iron loss can be reduced, and by using two or more welds, the stator core sheets can be maintained in a correct stacked state. Furthermore, by locating the multiple welds only on the back yoke surface of the yoke, the laminated strength is not too strong, allowing the split cores to be combined in a smooth annular shape, and iron loss due to residual stress can be reduced.

[0010] In a second embodiment of the present invention, in the electric motor according to the first embodiment, the welded portion is continuous from the stator core sheet arranged on one end face of the split core to the stator core sheet arranged on the other end face of the split core. According to this embodiment, the stacked shape of all the stator core sheets can be maintained.

[0011] In a third embodiment of the present invention, in the electric motor according to the first embodiment, each weld has a weld depth of 0.4 mm or less and a weld width of 0.8 mm or more. This embodiment can reduce iron loss and obtain a level of lamination strength that allows the stator core sheets to maintain a correct lamination state.

[0012] In the fourth embodiment of the present invention, the stator core sheets are not formed with a karamasa in the electric motor according to the first embodiment. According to this embodiment, iron loss due to the karamasa can be reduced, and the divided cores can be combined in a smooth annular shape, thereby reducing iron loss due to residual stress.

[0013] In a fifth embodiment of the present invention, in the electric motor according to the first embodiment, grooves are formed on the back yoke surface from the stator core sheet arranged on one end face of the split core to the stator core sheet arranged on the other end face of the split core, and welds are located in the grooves. This embodiment can reduce iron loss, and in an electric motor used in a compressor, for example, the refrigerant passages formed in the split cores can be used as the grooves.

[0014] In the sixth embodiment of the present invention, in the motor of the fifth embodiment, the welds are not positioned at the narrowest part where the distance from the slot is the smallest, which reduces the effect on the magnetic flux.

[0015] In the seventh embodiment of the present invention, in the motor of the sixth embodiment, when the inner peripheral length of the groove is L and the prohibited peripheral length centered on the narrowest part is M, the prohibited peripheral length M is determined as M = 0.005 × L, and no welds are positioned within the range of the prohibited peripheral length M. According to this embodiment, the effect on the magnetic flux can be reduced.

[0016] In an eighth embodiment of the present invention, in the electric motor according to the first embodiment, a relief groove is formed in the back yoke surface, and the relief groove is used as a welded portion so that the welded portion does not protrude from the back yoke surface. According to this embodiment, by not having the welded portion protrude from the back yoke surface, in an electric motor used in, for example, a compressor, the back yoke surface can be fixed with high precision to the inner peripheral surface of the sealed container.

[0017] A compressor according to a ninth embodiment of the present invention is a compressor using the electric motor according to any one of the first to eighth embodiments, in which the electric motor and the compression mechanism are disposed within a sealed container, and a stator having a plurality of divided cores arranged in an annular shape is fixed to the sealed container by a back yoke surface. According to this embodiment, a compressor with high motor efficiency can be provided.

[0018] The apparatus according to the tenth embodiment of the present invention is an apparatus using the compressor according to the ninth embodiment, in which the compressor, the condenser, the pressure reducing device, and the evaporator are connected in a ring shape by piping. According to this embodiment, an apparatus with high motor efficiency and excellent compression performance can be realized.

[0019] A compressor according to an embodiment of the present invention will be described below, but the present invention is not limited to the following embodiment.

[0020] FIG. 1 is a schematic diagram of a compressor using an electric motor according to this embodiment, and a refrigeration system using this compressor. The compressor 10 according to this embodiment is a rotary compressor. A sealed container 1 is connected to a suction pipe 2 for drawing in a refrigerant and a discharge pipe 3 for discharging the refrigerant. Inside the sealed container 1, a compression mechanism 13 for compressing the refrigerant drawn through the suction pipe 2 and a motor 14 for driving the compression mechanism 13 are disposed. The bottom of the sealed container 1 forms an oil reservoir 11. The compression mechanism 13 is composed of a cylinder 13a, a piston 13b, a vane (not shown), a main bearing 13c, and an auxiliary bearing 13d. The main bearing 13c is fixed to the sealed container 1. The piston 13b is rotatably fitted to an eccentric portion 4a of a rotary shaft 4 that passes through the cylinder 13a. The vane reciprocates in a vane groove following the piston 13b rolling along the inner wall surface of the cylinder 13a. The main bearing 13c and the auxiliary bearing 13d seal the upper and lower end surfaces of the cylinder 13a and support the rotating shaft 4. The electric motor 14 comprises a stator 30 fixed to the sealed container 1 and a rotor 20 arranged on the inner periphery of the stator 30. The rotor 20 is fixed to the rotating shaft 4, and the stator 30 is fixed to the sealed container 1. The refrigerant is drawn into the compression mechanism 13 from the suction pipe 2 and compressed in the compression mechanism 13. The refrigerant then passes through the electric motor 14 and is discharged from the discharge pipe 3.

[0021] In the refrigeration system according to this embodiment, a compressor 10, a condenser 17, a pressure reducing device 18, and an evaporator 19 are connected in a ring shape by piping. The condenser 17 condenses the refrigerant discharged from the discharge pipe 3, the pressure reducing device 18 reduces the pressure of the refrigerant condensed in the condenser 17, and the evaporator 19 evaporates the refrigerant reduced in pressure by the pressure reducing device 18. The refrigerant evaporated in the evaporator 19 is returned to the compressor 10 via the accumulator 16.

[0022] FIG. 2 is a perspective view of the main components of the electric motor according to this embodiment, with FIG. 2(a) being a perspective view of the rotor and stator, and FIG. 2(b) being a perspective view of the stator alone. The rotor 20 includes a rotor core 21 formed into a cylindrical shape by laminating rotor core sheets, and permanent magnets 22 arranged in slits formed on the outer periphery of the rotor core 21. The rotor 20 has a plurality of permanent magnets 22 arranged around the rotating shaft 4. The rotor core sheets are electromagnetic steel sheets with a thickness of approximately 0.3 mm, and the rotor core 21 is made of a magnetic material. The rotor core 21 has a through hole 23 in its center through which the rotating shaft 4 is disposed, and a plurality of rotor refrigerant passages 24 are formed axially around the through hole 23. The rotor refrigerant passages 24 are formed concentrically between the through hole 23 and the permanent magnets 22. The stator 30 is arranged with an air gap between it and the rotor 20. The stator 30 is formed by laminating stator core sheets in the axial direction of the rotating shaft 4. The stator core sheet is an electromagnetic steel sheet with a thickness of approximately 0.3 mm, and the stator 30 is made of a magnetic material. Note that no karamasa is formed on the stator core sheet. The stator 30 is made up of a plurality of split cores 30A, each divided into teeth 32 (see FIG. 3), arranged in a circular ring shape. The rotor 20 is arranged on the inner periphery of the plurality of split cores 30A arranged in a circular ring shape. A winding 41 is wound around each split core 30A.

[0023] FIG. 3 is a structural diagram showing a split core according to this embodiment, with FIGS. 3(a) and 3(c) being perspective structural views viewed from different directions, and FIG. 3(b) being a plan structural view. As shown in FIG. 3, the split core 30A has an arc-shaped yoke portion 31 centered on the rotation axis 4 of the rotor 20, teeth 32 extending from the yoke portion 31 toward the rotor 20, and umbrella portions 33 formed at the tips of the teeth 32. Slots 34 are formed between adjacent split cores 30A. Grooves 35 are formed in the back yoke surface of the yoke portion 31, extending from one stator end face to the other. The umbrella portions 33 are formed to extend beyond the circumferential width of the teeth 32 on both sides. The grooves 35 are formed on extensions of the center lines of the teeth 32 and are formed symmetrically with respect to the center line of the teeth 32. In this embodiment, all stator core sheets are fixed by two continuous welds 36 extending from the stator core sheet arranged on one end face of the split core 30A to the stator core sheet arranged on the other end face of the split core 30A. The welds 36 are located on the back yoke surface of the yoke portion 31, not on the teeth portions 32 and the umbrella portions 33. In FIG. 3 , the welds 36 are located in grooves 35.

[0024] FIG. 4 is an explanatory diagram showing the position of welds relative to the grooves. FIG. 4(a) is a plan view of the split core, and FIGS. 4(b) to 4(d) are enlarged views showing the positions of different welds. The grooves 35 in the split core 30A form refrigerant passages. The hatched areas in FIG. 4(a) indicate refrigerant passages. The electric motor 14 used in the compressor 10 is disposed within the sealed container 1 along with the compression mechanism 13. The stator 30, in which multiple split cores 30A are arranged in an annular shape, is fixed to the sealed container 1 by the back yoke surface. Therefore, the grooves 35 formed inside the back yoke surface form refrigerant passages. FIG. 4(b) shows a case where welds 36 are provided in the same positions as in FIG. 3. In this way, multiple welds 36 can be provided on the bottom surface 35a of the groove 35. Note that the surface facing the sealed container 1 is referred to as the bottom surface 35a of the groove 35. FIG. 4(c) shows a case where welds 36 are provided on each of a pair of side surfaces 35b forming the groove 35. FIG. 4D shows a case where a pair of inclined surfaces 35c formed on the opening surface of the groove 35 are provided with welds 36, respectively.

[0025] Figure 5 is an explanatory diagram showing the range in which a weld should not be positioned relative to the groove. Arrow A in Figure 5(a) indicates the shortest distance between slot 34 and groove 35. It is preferable not to position weld 36 at narrowest portion B of groove 35, where the distance from slot 34 is narrowest. Furthermore, when the inner peripheral length of groove 35 is L and the prohibited circumferential length centered on narrowest portion B is M, M = 0.005 × L is used to determine prohibited circumferential length M centered on narrowest portion B, and it is preferable not to position weld 36 within the prohibited circumferential length M. As shown in Figure 5(b), the range of prohibited circumferential length M centered on narrowest portion B is a range where magnetic flux density is extremely high. By positioning weld 36 outside the prohibited circumferential length M, the effect on magnetic flux can be reduced.

[0026] 6 is an explanatory diagram showing the position of the weld on the back yoke surface other than the groove. As shown in FIG. 6, when the weld 36 is to be positioned on the back yoke surface other than the groove 35, a relief groove 37 is formed in the back yoke surface and the weld 36 is positioned in the relief groove 37. The bulge caused by the bead generated by the welding is contained within the relief groove 37 and does not protrude from the back yoke surface. By not having the weld 36 protrude from the back yoke surface in this way, for example, in the electric motor 14 used in the compressor 10, the back yoke surface can be fixed with high precision to the inner peripheral surface of the sealed container 1.

[0027] FIG. 7 is an explanatory diagram showing the position of welds relative to grooves with shapes different from those shown in FIG. 4 . FIG. 7( a) is a plan view of the split core, FIG. 7( b) is a diagram showing the refrigerant passage, and FIGS. 7( c) and 7( d) are enlarged views of key portions showing the positions of different welds. The grooves 35 in the split cores 30A, shown as the hatched area in FIG. 7( b), form the refrigerant passages. The electric motor 14 used in the compressor 10 is disposed in the sealed container 1 together with the compression mechanism 13. The stator 30, in which multiple split cores 30A are arranged in an annular shape, is fixed to the sealed container 1 by the back yoke surface. Therefore, the grooves 35 formed inside the back yoke surface form the refrigerant passages. FIGS. 7( c) and 7( d) are enlarged views of the area enclosed by the dashed square line in FIG. 7( a), showing two welds 36 positioned within the grooves 35. In Figures 7(c) and 7(d), a pair of welds 36 are positioned symmetrically with respect to the deepest part C of the groove 35, but they do not necessarily have to be positioned symmetrically, and three or more welds 36 may be used.

[0028] Fig. 8 is an explanatory diagram showing the range in which a weld should not be positioned for the groove of the shape shown in Fig. 7, and Fig. 8(b) is an enlarged view of a main portion of Fig. 8(a). Arrow A in Fig. 8(a) indicates the shortest distance between slot 34 and groove 35. It is preferable that a weld 36 not be positioned at narrowest portion B of groove 35, where the distance from slot 34 is narrowest. Furthermore, when the inner surface circumferential length of groove 35 is L and the prohibited circumferential length centered on narrowest portion B is M, the prohibited circumferential length M centered on narrowest portion B is determined as M = 0.005 × L, and it is preferable that a weld 36 not be positioned within the range of prohibited circumferential length M.

[0029] 9 is an explanatory diagram showing the position of the weld on the back yoke surface other than the groove. As shown in FIG. 9, when the weld 36 is to be positioned on the back yoke surface other than the groove 35, a relief groove 37 is formed in the back yoke surface and the weld 36 is positioned in the relief groove 37. The bulge caused by the bead produced by welding is contained within the relief groove 37 and does not protrude from the back yoke surface. By not having the weld 36 protrude from the back yoke surface in this way, for example, in the electric motor 14 used in the compressor 10, the back yoke surface can be fixed with high precision to the inner peripheral surface of the sealed container 1.

[0030] Fig. 10 is a graph showing the relationship between welding and iron loss. As shown in Fig. 10, if the weld depth is at least 0.4 mm or less, iron loss can be kept below a predetermined level. Since the strength increases as the weld width increases, by setting the weld depth to 0.4 mm or less and the weld width to 0.8 mm or more, iron loss can be reduced and a level of lamination strength can be obtained that allows the stator core sheets to maintain a correct lamination state.

[0031] When manufacturing the electric motor 14, the multiple stator core sheets that make up the split core 30A can be stacked without connecting each of them by laminating, and the stacked stator core sheets can be integrated by laser welding at the portions that will become the back yoke surfaces of the yoke portion 31, and the integrated stator core sheets can be placed in a mold and resin material can be injected into the mold to form the insulator by insert molding. Therefore, iron loss due to entanglement to connect the individual stator core sheets does not occur, and a compressor 10 with high motor efficiency can be provided.

[0032] FIG. 11 is a configuration diagram of a compressor using a scroll compressor according to another embodiment, and a refrigeration system using this compressor. The compressor 10 according to this embodiment includes a sealed container 1, a compression mechanism 13 for compressing a refrigerant, and an electric motor 14 for driving the compression mechanism 13. The sealed container 1 is divided into one internal space and another internal space by the compression mechanism 13. The electric motor 14 is disposed in the other internal space. The other internal space is also divided by the electric motor 14 into a compression mechanism side space and an oil storage side space. An oil storage section 11 is disposed in the oil storage side space. A suction pipe 2 and a discharge pipe 3 are fixed to the sealed container 1 by welding. The suction pipe 2 and the discharge pipe 3 lead to the outside of the sealed container 1 and are connected to components constituting a refrigeration cycle. The suction pipe 2 introduces a refrigerant from outside the sealed container 1, and the discharge pipe 3 discharges the refrigerant from one internal space to the outside of the sealed container 1.

[0033] The main bearing member 7a is fixed inside the sealed container 1 by welding, shrink fitting, or the like, and supports the rotating shaft 4. One end of the rotating shaft 4 is supported by the main bearing member 7a, and the other end is supported by a bearing 7b. A fixed scroll 13j is bolted to the main bearing member 7a. The orbiting scroll 13k, which meshes with the fixed scroll 13j, is sandwiched between the main bearing member 7a and the fixed scroll 13j. The fixed scroll 13j and the orbiting scroll 13k form a scroll-type compression mechanism 13. A rotation restraining mechanism 9, such as an Oldham ring, is provided between the orbiting scroll 13k and the main bearing member 7a. The rotation restraining mechanism 9 prevents the orbiting scroll 13k from rotating and guides the orbiting scroll 13k to move in a circular orbit. The orbiting scroll 13k is eccentrically driven by an eccentric portion 4a provided at the upper end of the rotating shaft 4. By this eccentric drive, the compression chamber formed between the fixed scroll 13j and the orbiting scroll 13k moves from the outer periphery toward the center of the compression mechanism 13, reducing the volume and performing compression.

[0034] The electric motor 14 has a rotor 20 that is rotatably disposed about the rotary shaft 4, and a stator 30 that is disposed via an air gap with the rotor 20. The configuration of the electric motor 14 is the same as that shown in Fig. 2, and therefore a description thereof will be omitted.

[0035] Refrigerant is drawn into the compression mechanism 13 through the suction pipe 2 and compressed in the compression mechanism 13. The refrigerant is then discharged from the discharge pipe 3. In the refrigeration system according to this embodiment, a compressor 10, a condenser 17, a pressure reducing device 18, and an evaporator 19 are connected in a ring shape by piping. The condenser 17 condenses the refrigerant discharged from the discharge pipe 3, the pressure reducing device 18 reduces the pressure of the refrigerant condensed in the condenser 17, and the evaporator 19 evaporates the refrigerant reduced in pressure by the pressure reducing device 18. The refrigerant evaporated in the evaporator 19 is returned to the compressor 10 through the suction pipe 2.

[0036] The electric motor 14 according to this embodiment is suitable for a compressor 10 in which a compression mechanism 13 is connected to a rotary shaft 4 and a refrigerant is compressed by the compression mechanism 13. While this embodiment has been described using a vertical compressor 10, the same effect can be achieved with a horizontal compressor 10, and the electric motor 14 according to this embodiment is also suitable for an on-vehicle compressor, for example. While FIG. 1 shows a rotary compressor and FIG. 11 shows a scroll compressor, a reciprocating compressor or other compressors may also be used. Furthermore, in a refrigeration system in which the compressor 10 using the electric motor 14 according to this embodiment is connected in a ring shape with a condenser 17, a pressure reducing device 18, and an evaporator 19 by piping, high efficiency can be achieved without reducing torque.

[0037] As described above, the compressor 10 according to this embodiment has the compression mechanism 13 connected to the rotary shaft 4, and the refrigerant is compressed by the compression mechanism 13, thereby providing a compressor 10 with high motor efficiency. In addition, R32 or R410A can be used as the refrigerant, and natural refrigerants such as R290 and CO ２ A refrigerant may also be used.

[0038] As described above, in the electric motor 14 according to this embodiment, the welds 36 for fastening the multiple stator core sheets are positioned on the back yoke surface of the yoke portion 31, rather than on the teeth portion 32 and the umbrella portion 33, thereby reducing iron loss. The use of two or more welds 36 allows the stator core sheets to maintain a proper stacked state. Furthermore, by positioning the multiple welds 36 only on the back yoke surface of the yoke portion 31, the laminated strength is not too strong, allowing the split cores 30A to be assembled in a smooth circular shape, thereby reducing iron loss due to residual stress. Furthermore, by making the welds 36 continuous from the stator core sheet located on one end surface of the split core 30A to the stator core sheet located on the other end surface of the split core 30A, the stacked shape of all the stator core sheets can be maintained. Furthermore, by not forming a stator core sheet with a void, iron loss due to the void can be reduced. The split cores 30A can be assembled in a smooth circular shape, thereby reducing iron loss due to residual stress. In addition, a groove 35 is formed on the back yoke surface from the stator core sheet located on one end face of the split core 30A to the stator core sheet located on the other end face of the split core 30A. By positioning the welded portion 36 in the groove 35, iron loss can be reduced, and in the case of the electric motor 14 used in the compressor 10, for example, the refrigerant passage formed in the split core 30A can be used as the groove 35.

[0039] The compressor of the present invention is useful for appliances such as hot water heating systems, indoor air conditioners, vehicle air conditioners, water heaters, refrigerators, showcases, chillers, and freezers.

[0040] REFERENCE SIGNS LIST 1 sealed container 2 suction pipe 3 discharge pipe 4 rotating shaft 4a eccentric portion 7a main bearing member 7b bearing 9 rotation restraint mechanism 10 compressor 11 oil reservoir 13 compression mechanism 13a cylinder 13b piston 13c main bearing 13d auxiliary bearing 13j fixed scroll 13k orbiting scroll 14 electric motor 16 accumulator 17 condenser 18 pressure reducing device 19 evaporator 20 rotor 21 rotor core 22 permanent magnet 23 through hole 24 rotor refrigerant passage 30 stator 30A split core 31 yoke portion 32 teeth portion 33 umbrella portion 34 slot 35 groove 35a bottom surface 35b side surface 35c inclined surface 36 welded portion 37 relief groove 41 Winding A Arrow (shortest distance) B Narrowest part C Deepest part L Inner surface perimeter M Prohibited perimeter

Claims

1. An electric motor in which a plurality of split cores are divided into teeth and arranged in a ring shape, a rotor is arranged on the inner circumference of the plurality of split cores arranged in a ring shape, the split cores are constructed by stacking a plurality of stator core sheets, the split cores have an arc-shaped yoke portion centered on the rotation axis of the rotor, the teeth extending from the yoke portion towards the rotor, and umbrella portions formed at the tips of the teeth, slots are formed between adjacent split cores, and windings are wound around the teeth, wherein the welds that secure the plurality of stator core sheets are located on the back yoke surface of the yoke portion rather than on the teeth and umbrella portions, and there are two or more welds.

2. The electric motor according to claim 1, characterized in that the welded portion is continuous from the stator core sheet arranged on one end face of the split core to the stator core sheet arranged on the other end face of the split core.

3. The electric motor according to claim 1, characterized in that each of the welds has a welding depth of 0.4 mm or less and a welding width of 0.8 mm or more.

4. The electric motor according to claim 1, characterized in that the stator core sheet is not formed with a karamasae.

5. The electric motor according to claim 1, characterized in that a groove is formed on the back yoke surface from the stator core sheet arranged on one end surface of the split core to the stator core sheet arranged on the other end surface of the split core, and the weld is located in the groove.

6. The electric motor according to claim 5, wherein the welded portion is not positioned at the narrowest portion where the distance from the slot is narrowest.

7. The electric motor according to claim 6, characterized in that, when the inner peripheral length of the groove is L and the prohibited peripheral length centered on the narrowest part is M, the prohibited peripheral length M is determined as M = 0.005 x L, and the welded portion is not positioned within the range of the prohibited peripheral length M.

8. The electric motor according to claim 1, wherein a relief groove is formed on the back yoke surface, the relief groove serves as the welded portion, and the welded portion does not protrude from the back yoke surface.

9. A compressor using the electric motor according to any one of claims 1 to 8, wherein the electric motor and a compression mechanism are arranged in a sealed container, and a stator having a plurality of split cores arranged in an annular shape is fixed to the sealed container by the back yoke surface.

10. Equipment using the compressor according to claim 9, characterized in that the compressor, condenser, pressure reducing device and evaporator are connected in a circular configuration by piping.

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