DESCRIPTION
Title of Invention COMPRESSOR Technical Field [0001]
The present invention relates to a compressor in which a tubular hermetic container, and a stator accommodated in the hermetic container are fit together, and fixed to each other by welding. Background Art [0002]
In some proposed compressors, a tubular hermetic container, and a stator accommodated in the hermetic container are fit together, and fixed to each other by welding (see, for example, Patent Literature 1). There are also compressors in which welding between the hermetic container and the stator is performed by welding the hermetic container and the stator together at a position on the line connecting the circumferentially central portion of one of the tooth portions of the stator with the center of the stator core (see, for example, Patent Literature 2). Citation List Patent Literature [0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2009-047062
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2010-236422 Summary of Invention Technical Problem [0004]
However, the proposed compressors described above have the following problem. That is, a silicon steel sheet, which is the material of which the stator is

welding the hermetic container and the stator together, air bubbles (gas produced as a substance such as carbon present in the material combines with oxygen) may sometimes form as the stator melts. In some cases, a defect called blowhole may occur at the weld joint between the hermetic container and the stator. The presence of such a defect may potentially reduce the strength of fixing between the stator and the hermetic container. [0005]
The present invention has been made to address the above-mentioned problem, and it is an object of the present invention to provide a compressor with reduced risk of blowhole formation at the joint between the hermetic container and the stator.
Solution to Problem [0006]
According to an embodiment of the present invention, there is provided a compressor including a hermetic container having a tubular shape, a compression element accommodated in the hermetic container and configured to compress refrigerant gas, and an electric motor accommodated in the hermetic container and configured to drive the compression element. The electric motor includes a stator that is fit and welded onto the hermetic container. The stator includes a stator core. The stator core includes a back yoke portion having an annular shape, and a plurality of tooth portions projecting radially inward from the back yoke portion. The stator core has a depression in at least one location in an outer edge portion of the back yoke portion. The depression corresponds to a hermetic space between the hermetic container and the back yoke portion. A weld joint that welds the hermetic container and the stator together extends via the depression. Advantageous Effects of Invention [0007]
With the compressor according to an embodiment of the present invention, the stator core includes, in at least one location in the outer edge portion of the back yoke portion, a depression that corresponds to a hermetic space between the hermetic

container and the back yoke portion. Further, a weld joint that welds the hermetic container and the stator together extends via the depression. Consequently, air bubbles are caused to readily escape to the depression from the weld area during welding, thus reducing the occurrence of a defect called blowhole in the weld joint. Consequently, the strength of fixing between the stator and the hermetic container is allowed to maintain in the hermetic compressor. Brief Description of Drawings [0008]
[Fig. 1] Fig. 1 is a cross-sectional view of the interior of a compressor according to Embodiment 1 of the present invention.
[Fig. 2] Fig. 2 is a cross-sectional view taken along a line A-A in Fig. 1.
[Fig. 3] Fig. 3 is a cross-sectional view taken along the line A-A in Fig. 1, illustrating the location of a depression.
[Fig. 4] Fig. 4 is a plan view of a first magnetic steel sheet having a cutout in an outer peripheral edge portion.
[Fig. 5] Fig. 5 is a plan view of a second magnetic steel sheet, which is placed in close contact with the inner wall of a hermetic container.
[Fig. 6] Fig. 6 includes partial enlarged views of a hermetic container 2 and a stator 5, illustrating a method for fixing the hermetic container 2 and the stator 5 to each other.
[Fig. 7] Fig. 7 illustrates a blowhole formed in a weld joint.
[Fig. 8] Fig. 8 illustrates a comparative example of a hermetic compressor with a weld joint provided in the cavity between a stator and a hermetic container.
[Fig. 9] Fig. 9 is a cross-sectional view taken along a line B-B in Fig. 8. Description of Embodiments [0009] Embodiment 1
Fig. 1 is a cross-sectional view of the interior of a compressor according to Embodiment 1 of the present invention. Fig. 1 illustrates a cross-section of a hermetic compressor 1. A single-cylinder rotary compressor will be described below

as an example of the hermetic compressor 1. The hermetic compressor 1 includes a tubular hermetic container 2 including an upper container 2a and a lower container 2b, a compression element 3 accommodated in the hermetic container 2 to compress refrigerant gas, and an electric motor 4 accommodated in the hermetic container 2 to drive the compression element 3. The compression element 3 and the electric motor 4 are connected by a crankshaft 7. The compression element 3 is accommodated in a lower portion of the hermetic container 2, and the electric motor 4 is accommodated in an upper portion of the hermetic container 2. The upper container 2a is connected with a discharge pipe 8. The lower container 2b is connected with a suction connecting pipe 10 on which a suction muffler 9 is attached. The discharge pipe 8 is a connection pipe through which high-temperature, high-pressure refrigerant gas in the hermetic container 2 that has been compressed by the compression element 3 is directed into a refrigerant pipe. The suction connecting pipe 10 is a connection pipe through which low-temperature, low-pressure refrigerant gas entering via the suction muffler 9 is delivered into the compression element 3. [0010]
The compression element 3 is fixed onto the interior of the hermetic container 2 by welding. The compression element 3 includes a rolling piston 13 accommodated in a cylinder 11. The rolling piston 13 is brought into fitting engagement with an eccentric portion 12 of the crankshaft 7. The cylinder 11 and the rolling piston 13 define a compression chamber as a vane (not illustrated) that reciprocates radially in a groove provided in the cylinder 11 makes contact with the outer periphery of the rolling piston 13. The openings at the opposite axial ends of the cylinder 11 are closed by a main bearing 14 and a sub-bearing 15. A discharge muffler 16 is disposed over the main bearing 14 to muffle the sound of refrigerant gas discharged from the compression element 3. A muffler discharge port 17 is provided in an upper portion of the discharge muffler 16 to discharge refrigerant gas into the hermetic container 2. The compression element 3 compresses refrigerant gas as the drive force of the electric motor 4 is transmitted to the compression element 3 via the crankshaft 7.

[0011]
The electric motor 4 includes a stator 5 that is fit and welded onto the hermetic container 2, and a rotor 6 disposed adjacent to the inner periphery of the stator 5 in such a manner that the rotor 6 is allowed to rotate. The crankshaft 7 that extends downwardly is attached to the rotor 6. The crankshaft 7 is supported by the main bearing 14 and the sub-bearing 15 in such a manner that the crankshaft 7 is allowed to rotate. The crankshaft 7 rotates together with the rotor 6. A lead wire 18 of the stator 5 is connected to a glass terminal 19, which is provided to the upper container 2a to supply electric power from outside of the hermetic container. [0012]
Fig. 2 is a cross-sectional view taken along a line A-A in Fig. 1. In Fig. 2, the rotor 6 and the crankshaft 7 are not illustrated for the convenience of description of the hermetic container 2 and the stator 5. The stator 5 will be described below with reference to Figs. 1 and 2. The stator 5 includes a stator core 51. The stator core 51 includes an annular back yoke portion 53, and a plurality of tooth portions 54 projecting radially inward from the back yoke portion 53. The stator 5 also includes a plurality of phases of windings 52 applied to the stator core 51 with an insulator (not illustrated) each interposed between the stator core 51 and the windings 52. Each winding 52 is disposed in the gap between adjacent tooth portions 54. [0013]
The stator core 51 is formed as a laminated stack of a plurality of magnetic steel sheets made of a high-permeability material. Examples of magnetic steel sheets include silicon steel sheets. An insulator (not illustrated) as an insulating component is disposed at the upper and lower ends of the tooth portions 54 of the stator core 51 in the direction of the cylinder axis to insulate the tooth portions 54 and windings 52 of the stator core 51 from each other. The windings 52 are wound in a concentrated fashion around the tooth portions 54 of the stator core 51 with the insulator each interposed between the tooth portions 54 and the windings 52. [0014]

As illustrated in Figs. 1 and 2, the stator core 51 includes a depression 55 in at least one location in the outer edge portion of the back yoke portion 53. The depression 55 corresponds to a hermetic space S between the hermetic container 2 and the back yoke portion 53. The depression 55 is a portion of the annular stator core 51 that is depressed in the circumferential direction and in the stacking direction (Z-axis direction) from the outer periphery toward the inner periphery. Although the depression 55 is a portion of the stator core 51 depressed from the outer periphery toward the inner periphery, the depression 55 does not penetrate the stator core 51 from the outer periphery to the inner periphery. The depression 55 is provided in the stator core 51 in such a manner that the depression 55 is positioned in a weld joint 20 where the hermetic container 2 and the stator 5 are welded together. In Fig. 2, the depression 55 is provided in each of four locations in the circumferential direction of the stator core 51. The depression 55 may not necessarily be provided in four locations. Depending on the number of the tooth portions 54 in the stator core 51, the depression 55 may be provided in one or each of more locations in the circumferential direction of the stator core 51. In Fig. 1, the depression 55 is provided in one location in the stacking direction (Z-axis direction) of the stator core 51. The depression 55 may not necessarily be provided in one location in the stacking direction (Z-axis direction) of the stator core 51 but may be provided in each of a plurality of locations in the stacking direction (Z-axis direction). The space defined between the inner wall of the hermetic container 2 and the depression 55 of the stator 5 corresponds to the hermetic space S. [0015]
Fig. 3 is a cross-sectional view taken along the line A-A in Fig. 1, illustrating the location of a depression. The location of the depression 55 will be described below in further detail with reference to Figs. 2 and 3. As illustrated in Fig. 2, the depression is provided at a portion of the back yoke portion 53 that is located between two circumferentially adjacent tooth portions 54. Alternatively, as illustrated in Fig. 3, the depression 55 may be provided between a first imaginary plane F1, which is an imaginary plane passing through the center 0 of the stator core 51 and

the circumferentially central portion of one of the tooth portions 54, and a second imaginary plane F2, which is an imaginary plane passing through the center 0 of the stator core 51 and the circumferentially central portion of another one of the tooth portions 54 that is located adjacent to the first imaginary plane F1. Although the first imaginary plane F1 and the second imaginary plane F2 are represented by dotted lines in Fig. 3, the first imaginary plane F1 and the second imaginary plane F2 are formed as planes perpendicular to the plane of the drawing. Although the relationship between the first and second imaginary planes F1 and F2, and the depression 55 has been described above by use of the depression 55 provided in one of the four locations illustrated in Fig. 3, the same applies to the depression 55 provided in each of the other three locations. Next, a method for forming the depression 55 will be described. [0016]
Fig. 4 is a plan view of a first magnetic steel sheet having a cutout in an outer peripheral edge portion. Fig. 5 is a plan view of a second magnetic steel sheet, which is placed in close contact with the inner wall of the hermetic container. The stator core 51 is formed by stacking a plurality of first magnetic steel sheets 51a each having a cutout 55a in an outer peripheral edge portion, stacking at least one of a plurality of second magnetic steel sheets 51b at one end in the stacking direction in which the first magnetic steel sheets 51a are stacked, stacking remaining of the plurality of second magnetic steel sheets 51 b at the other end in the stacking direction, and placing the plurality of second magnetic steel sheets 51b in close contact with the inner wall of the hermetic container 2. At each end in the stacking direction in which the first magnetic steel sheets 51a are stacked, one of the first magnetic steel sheets 51 a and one of the second magnetic steel sheets 51 b are in contact with each other. As illustrated in Fig. 4, the cutout 55a is formed by cutting away a portion of the outer peripheral edge of the first magnetic steel sheet 51a having an annular shape. As illustrated in Fig. 5, the cutout 55a provided in the first magnetic steel sheet 51a is not provided in the second magnetic steel sheet 51b. The depression 55 corresponds to the cutouts 55a obtained by stacking the plurality

of first magnetic steel sheets 51a, stacking at least one of the plurality of second magnetic steel sheets 51 b at one end in the stacking direction in which the first magnetic steel sheets 51a are stacked, and stacking remaining of the plurality of second magnetic steel sheets 51b at the other end in the stacking direction. That is, the depression 55 is formed in the stator core 51 as the cutouts 55a are arranged in succession by stacking magnetic steel sheets. In the stator core 51, the stack of the first magnetic steel sheets 51a is in contact with one of the second magnetic steel sheets 51b at each end in the stacking direction in which the first magnetic steel sheets 51a are stacked as illustrated in Fig. 1. The upper and lower ends of the depression 55 in the stacking direction (Z-axis direction) of magnetic steel sheets are thus each closed by one of the second magnetic steel sheets 51b. Further, the depression 55 corresponds to the hermetic space S between the hermetic container 2 and the back yoke portion 53. [0017]
Fig. 6 includes partial enlarged views of the hermetic container 2 and the stator 5, illustrating a method for fixing the hermetic container 2 and the stator 5 onto each other. The following describes how the hermetic container 2 and the stator 5 are fixed onto each other. The stator 5 is brought into fitting engagement with the hermetic container 2 as illustrated in Fig. 6(a). Then, the stator 5 is fixed to the hermetic container 2 by welding as illustrated in Fig. 6(b). The fitting engagement between the hermetic container 2 and the stator 5 is desirably performed by press-fitting or shrink-fitting. When the fitting engagement between the hermetic container 2 and the stator 5 is to be performed by loose fitting, the hermetic container 2 and the stator 5 are brought into fitting engagement with each other in such a manner that the gap between the hermetic container 2 and the stator 5 is smaller than the size of a spatter described later. [0018]
The hermetic container 2 and the stator 5 are welded together by arc welding such as MAG welding. For example, as illustrated in Fig. 6(b), a welding torch 30 is used to weld the stator 5 and the hermetic container 2 together via a weld hole 21,

which extends through the hermetic container 2 from the outer periphery to the inner periphery. The hermetic container 2 and the stator 5 may not necessarily be welded together by arc welding. For example, the hermetic container 2 and the stator 5 may be welded together by, for example, other methods of welding such as laser welding. [0019]
Next, the positional relationship between the weld joint 20, and the tooth portions 54 of the stator 5 will be described below. As illustrated in Fig. 2, the winding 52 is wound around each of the tooth portions 54 with an insulator (not illustrated) each interposed between the tooth portion 54 and the winding 52. The winding 52 is coated with an insulating covering material. The insulator and the covering material serve to provide electrical insulation between the tooth portion 54 and the winding 52. The insulator and the covering material each have a heat-resistant temperature lower than the temperature of welding. For this reason, there is a risk that the insulator and the covering material may melt due to heat generated during welding, or may break as the winding moves due to thermal expansion or contraction. Typically, the winding 52 is wound in close contact with the tooth portion 54. When the stator 5 is welded at a position on the first imaginary plane F1 or second imaginary plane F2, which is an imaginary plane passing through the center 0 of the stator core 51 and the circumferentially central portion of one of the tooth portions 54, the heat due to welding tends to be transmitted to the tooth portion 54 via the back yoke portion 53, and then transmitted from the tooth portion 54 to the winding 52 placed in close contact with the tooth portion 54. For this reason, when the stator 5 is welded at a position on the first imaginary plane F1 or second imaginary plane F2, which is an imaginary plane passing through the center of the stator core 51 and the circumferentially central portion of one of the tooth portions 54, the heat due to welding may potentially cause the insulator or the covering material to melt or break. Consequently, as illustrated in Fig. 2, the weld joint 20 is provided at a portion of the back yoke portion 53 that is located between two circumferentially adjacent tooth portions 54 and is not in contact with the winding 52. Alternatively, as illustrated in Fig. 3, the weld joint 20 is provided between the first imaginary plane F1,

which passes through the center 0 of the stator core 51 and the circumferentially central portion of one of the tooth portions 54, and the second imaginary plane F2, which passes through the center 0 of the stator core 51 and the circumferentially central portion of another one of the tooth portions 54 that is located adjacent to the first imaginary plane F1. Further, the weld joint 20 extends via the depression 55. [0020]
Fig. 7 illustrates a blowhole formed in the weld joint. In welding the stator 5 and the hermetic container 2 together, air bubbles (gas produced as a substance such as carbon present in the material of the stator 5 combines with oxygen) may sometimes form as the stator 5 melts, resulting in the occurrence of a defect called a blowhole 22 in the weld joint 20. Occurrence of the blowhole 22 leads to reduced strength of fixing between the stator and the hermetic container. It is thus desirable to reduce the occurrence of the blowhole 22. In the hermetic compressor 1, the weld joint 20 extends via the depression 55. Consequently, air bubbles are caused to readily escape to the depression 55 from the weld joint 20 during welding, thus reducing the occurrence of the blowhole 22 in the weld joint 20. [0021]
Next, operation of the hermetic compressor 1 will be described. As the crankshaft 7 is driven by the electric motor 4 and rotates, the rolling piston 13 in the cylinder 11 also rotates together with the crankshaft 7. As the rolling piston 13 rotates, the vane accommodated in the rolling piston 13 rotates eccentrically while making a piston movement. At this time, refrigerant gas flows via the suction connecting pipe 10 into a compression chamber bounded by the inner wall of the cylinder 11, the rolling piston 13, and the vane, through the suction port of the compression element 3. Then, the refrigerant gas in the compression chamber is compressed as the volume inside the compression chamber decreases with the rotation of the rolling piston 13. The compressed refrigerant gas flows, via a groove communicating with the interior of the cylinder 11, into the interior space of the discharge muffler 16 from a discharge port provided in the main bearing 14. The refrigerant gas is then discharged from the muffler discharge port 17 to Space A,

which is a space in the hermetic container 2 located between the electric motor 4 and the compression element 3. The refrigerant gas discharged to Space A reaches an upper area inside the hermetic container 2. The refrigerant gas is then discharged from the discharge pipe 8 to the outside of the hermetic container 2. [0022]
As described above, the stator core 51 of the hermetic compressor 1 includes, in at least one location in the outer edge portion of the back yoke portion 53, the depression 55 that corresponds to the hermetic space S between the hermetic container 2 and the back yoke portion 53. The weld joint 20, which welds the hermetic container 2 and the stator 5 together, extends via the depression 55. Consequently, air bubbles are caused to readily escape to the depression 55 from the weld joint 20 during welding, thus reducing the occurrence of a defect called blowhole in the weld joint 20. Consequently, the strength of fixing between the stator 5 and the hermetic container 2 is allowed to maintain in the hermetic compressor 1. [0023]
Fig. 8 illustrates a comparative example of a hermetic compressor with a weld joint provided in the cavity between the stator and the hermetic container. Fig. 9 is a cross-sectional view taken along a line B-B in Fig. 8. In Fig. 8, the rotor 6 and the crankshaft 7 are not illustrated for the convenience of description of the weld joint 20 between the hermetic container 2 and the stator 5. Features identical to those of the hermetic compressor in Figs. 1 to 7 are denoted by the same reference signs and will not be described in further detail. A hermetic compressor 101 represents a comparative example to the hermetic compressor 1. The hermetic compressor 101 includes a cavity 155 between a hermetic container 102 and a stator 105. The cavity 155 communicates with the lower space of the hermetic container 102. A weld joint 120 is provided in the cavity 155. That is, the cavity 155 is not a hermetic space. As described above, the hermetic compressor 101 includes, between the hermetic container 102 and the stator 105, the cavity 155 that communicates with the lower space of the hermetic container 102 and is not a hermetic space. Due to the presence of the cavity 155, molten objects called spatters 23 may sometimes during

welding fly to the interior space of the hermetic container 102. When molten objects called the spatters 23 fly to the interior space of the hermetic container 102, the molten objects enter the compression element 3 and thus make the compression element 3 inoperative. [0024]
With the hermetic compressor 1 according to Embodiment 1, the stator core 51 includes, in at least one location in the outer edge portion of the back yoke portion 53, the depression 55 that corresponds to the hermetic space S between the hermetic container 2 and the back yoke portion 53. Further, the weld joint 20, which welds the hermetic container 2 and the stator 5 together, extends via the depression 55. This configuration of the hermetic compressor 1 ensures that any spatters are confined in the hermetic space S during welding, thus preventing the spatters from entering the compression element 3. [0025]
In the hermetic compressor 1, a stack of the first magnetic steel sheets 51a is stacked in contact with one of the second magnetic steel sheets 51 b at each end in the stacking direction in which the first magnetic steel sheets 51a are stacked. Consequently, the upper and lower ends of the depression 55 in the stacking direction (Z-axis direction) of magnetic steel sheets are each closed by one of the second magnetic steel sheets 51 b. The depression 55 corresponds to the hermetic space S between the hermetic container 2 and the back yoke portion 53. This configuration of the hermetic compressor 1 ensures that any spatters are confined in the hermetic space S during welding, thus preventing the spatters from entering the compression element 3. [0026]
When the hermetic container and the stator are welded together at a position on the line connecting the circumferentially central portion of one of the tooth portions with the center of the stator core, there is a risk that the insulator between the stator and the winding, or the covering layer of the winding may melt or break due to heat generated during welding and transmitted from the teeth portion. In this respect,

with the hermetic compressor 1 according to Embodiment 1, the depression 55 is provided at a portion of the back yoke portion 53 that is located between two circumferentially adjacent tooth portions 54, and the weld joint 20 that welds the hermetic container 2 and the stator 5 together extends via the depression 55. Alternatively, the depression 55 is provided between the first imaginary plane F1, which passes through the center 0 of the stator core 51 and the circumferentially central portion of one of the tooth portions 54, and the second imaginary plane F2, which passes through the center 0 of the stator core 51 and the circumferentially central portion of another one of the tooth portions 54 that is located adjacent to the first imaginary plane F1, and the weld joint 20 that welds the hermetic container 2 and the stator 5 together extends via the depression 55. This configuration results in increased distance between the weld joint 20 and the tooth portions 54. Consequently, the hermetic container 2 and the stator 5 can be welded together without causing the insulator between the stator 5 and the winding 52 and the covering layer of the winding 52 to melt or break due to heat generated during welding. [0027]
The stator core 51 is formed by stacking the plurality of first magnetic steel sheets 51a each having a cutout in an outer peripheral edge portion, stacking at least one of the plurality of second magnetic steel sheets 51b at one end in the stacking direction in which the first magnetic steel sheets 51a are stacked, stacking remaining of the plurality of second magnetic steel sheets 51 b at the other end in the stacking direction, and placing the plurality of second magnetic steel sheets 51b in close contact with the inner wall of the hermetic container 2. The depression 55 corresponds to the cutouts 55a. When the depression 55 is formed in the stator core 51 through a machining process, a risk is thus introduced that the insulation coating on the magnetic steel sheets of the stator 5 may come off, resulting in passage of electric current between the magnetic steel sheets and the consequent decrease in motor efficiency. In this respect, the stator core 51 is formed by stacking the plurality of first magnetic steel sheets 51a each having a cutout in an outer peripheral edge

portion, stacking at least one of the plurality of second magnetic steel sheets 51 b at one end in the stacking direction in which the first magnetic steel sheets 51a are stacked, stacking remaining of the plurality of second magnetic steel sheets 51b at the other end in the stacking direction, and placing the plurality of second magnetic steel sheets 51 b in close contact with the inner wall of the hermetic container 2. The depression 55 corresponds to the cutouts 55a. This configuration allows the depression 55 to be formed without breaking the insulation coating on the magnetic steel sheets, thus preventing a decrease in motor efficiency. [0028]
With the hermetic compressor 1 according to Embodiment 1, the depression 55 is provided at a portion of the back yoke portion 53 that is located between two circumferentially adjacent tooth portions 54. Alternatively, the depression 55 is provided between the first imaginary plane F1, which passes through the center 0 of the stator core 51 and the circumferentially central portion of one of the tooth portions 54, and the second imaginary plane F2, which passes through the center 0 of the stator core 51 and the circumferentially central portion of another one of the tooth portions 54 that is located adjacent to the first imaginary plane F1. When a cavity is present on the line connecting the circumferentially central portion of one of the tooth portions with the center of the stator core, the cavity acts as a magnetic resistance, leading to a decrease in motor efficiency. As the depression 55 is positioned as described above in the hermetic compressor 1 according to Embodiment 1, the depression 55 does not act as a magnetic resistance. Consequently, motor efficiency is not caused to decrease. [0029]
The present invention is not limited to Embodiment 1 described above but may be practiced with various modifications. For example, although a rotary compressor has been described above as an example of a hermetic compressor, hermetic compressors of any compression structure may be employed as long as the electric motor is disposed inside the hermetic container, such as a scroll hermetic compressor and a reciprocating hermetic compressor. Further, the stator 5 illustrated in Fig. 2 is

made from a single non-segmented annular stator core 51. However, the stator 5 may not necessarily be made from a single non-segmented annular stator core 51. Alternatively, for example, the stator 5 may be made up of a plurality of substantially T-shaped stator cores arranged circumferentially and combined in an annular shape. Reference Signs List [0030]
1 hermetic compressor 2 hermetic container 2a upper container 2b lower container 3 compression element 4 electric motor 5 stator 6 rotor 7 crankshaft 8 discharge pipe 9 suction muffler 10 suction connecting pipe 11 cylinder 12 eccentric portion 13 rolling piston 14 main bearing 15 sub-bearing 16 discharge muffler 17 muffler discharge port 18 lead wire 19 glass terminal 20 weld joint 21 weld hole 22 blowhole 23 spatter 30 welding torch 51 stator core 51a first magnetic steel sheet 51b second magnetic steel sheet 52 winding 53 back yoke portion 54 tooth portion 55 depression 55a cutout 101 hermetic compressor 102 hermetic container 105 stator 120 weld joint 155 cavity

WE CLAIM:
[Claim 1]
A compressor, comprising:
a hermetic container having a tubular shape;
a compression element accommodated in the hermetic container and configured to compress refrigerant gas; and
an electric motor accommodated in the hermetic container and configured to drive the compression element,
the electric motor including a stator that is fit and welded onto the hermetic container,
the stator including a stator core, the stator core including a back yoke portion and a plurality of tooth portions, the back yoke portion having an annular shape, the plurality of tooth portions projecting radially inward from the back yoke portion,
the stator core having a depression in at least one location in an outer edge portion of the back yoke portion, the depression corresponding to a hermetic space between the hermetic container and the back yoke portion,
a weld joint that welds the hermetic container and the stator together extending via the depression. [Claim 2]
The compressor of claim 1, wherein the depression is provided at a portion of the back yoke portion that is located between two circumferentially adjacent tooth portions of the plurality of tooth portions. [Claim 3]
The compressor of claim 1 or 2, wherein the depression is provided between a first imaginary plane and a second imaginary plane, the first imaginary plane passing through a center of the stator core and a circumferentially central portion of one of the plurality of tooth portions, the second imaginary plane passing through the center of the stator core and a circumferentially central portion of an other one of the plurality of tooth portions that is located adjacent to the first imaginary plane. [Claim 4]

The compressor of any one of claims 1 to 3,
wherein the stator core is formed by stacking a plurality of first magnetic steel sheets and a plurality of second magnetic steel sheets, the plurality of first magnetic steel sheets each having a cutout in an outer peripheral edge portion, at least one of the plurality of second magnetic steel sheets being stacked at one end in a stacking direction in which the plurality of first magnetic steel sheets are stacked, remaining of the plurality of second magnetic steel sheets being stacked at an other end in the stacking direction, the plurality of second magnetic steel sheets being placed in close contact with an inner wall of the hermetic container, and
wherein the depression corresponds to the cutouts.