DESCRIPTION
Title of Invention
SEALED COMPRESSOR AND REFRIGERATION CYCLE APPARATUS
INCLUDING THE SEALED COMPRESSOR
Technical Field
[0001]
The present invention relates to a sealed compressor that compresses refrigerant gas, and a refrigeration cycle apparatus including the sealed compressor. Background Art [0002]
Conventional sealed compressors include, for example, a type formed by perforating a container, shrink-fitting a compression mechanism unit in the container, and pouring a weld metal from outsides of the holes, thereby weld-fixing internal components including the compression mechanism unit in the container (see, for example, Patent Literature 1). [0003]
Another type of the conventional sealed compressor is formed by fixing the internal components including the compression mechanism unit in the container, without welding. Such a sealed compressor is formed, for example, by forming an engaging recess in the outer circumferential portion of the compression mechanism unit to recede in a radial direction orthogonal to the axial direction, and pressing, with a pressing jig, a portion of the container opposing the engaging recess of the compression mechanism unit radially inwardly, to thereby plastically deform the portion of the container opposing the engaging recess of the compression mechanism unit to fit into the engaging recess, thus fixing the compression mechanism unit in the container (see, for example, Patent Literature 2). [0004]
Another example of the sealed compressor formed by fixing the internal components including the compression mechanism unit in the container, without welding, is formed as follows. Such a sealed compressor is formed, for example, by

forming a plurality of engaging recesses in the outer circumferential portion of the compression mechanism unit to recede in a radial direction orthogonal to the axial direction, heating each of portions of the container opposing the corresponding one of engaging recesses of the compression mechanism unit, and pressing the heated portions of the container radially inwardly with a pressing jig, to thereby form a protrusion to be engaged with the engaging recess, on each of the heated portions of the container. These protrusions tightly hold the portion between the engaging recesses of the compression mechanism unit by thermal contraction provoked by the cooling of the container, thereby fixing the compression mechanism unit in the container (see, for example, Patent Literature 3). Citation List Patent Literature [0005]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 6-272677 (Fig. 1 to Fig. 3 and paragraph [0020])
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 6-509408 (Fig. 1 to Fig. 3)
Patent Literature 3: Japanese Unexamined Patent Application Publication No. 2005-330827 (Claim 6, Fig. 1, and Fig. 2) Summary of Invention Technical Problem [0006]
In the case where the compression mechanism unit is fixed in the container by welding as disclosed in Patent Literature 1, FC cast iron (gray cast iron), which has a high weldability, is often adopted as material of the compression mechanism unit. However, products formed by casting are generally inferior in accuracy of size and surface roughness, and thus the appearance has to be refinished by mechanical processing, impeding reduction of the processing cost.
Another sintering material is known that provides high molding accuracy and low processing cost. A sintered body formed of the sintering material is obtained by

sintering metal powder. However, the sintered body contains voids inside, and hence has low weldability, and the strength after the welding is lower than the cast iron. Thus, the sintered body has seldom been adopted as material of the sealed compressor formed by fixing the compression mechanism unit in the container by welding. [0007]
In contrast, in the sealed compressor formed by fixing the internal components including the compression mechanism unit in the container without welding, as disclosed in Patent Literatures 2 and 3, the engaging recesses receding in the radial direction orthogonal to the axial direction have to be formed in the outer circumferential portion of the compression mechanism unit, as described above. In addition, when the sintering material is used to manufacture the internal components including the compression mechanism unit, pressing and heating are required to solidify the sintering material. [0008]
When the shape of the internal components including the compression mechanism unit manufactured from the sintering material includes a boss and a flange, for example like a bearing, the sintering mold is configured as follows.
The sintering mold includes a die having a cavity in which the sintering material is accommodated, and a core rod slidably disposed inside the cavity of the die, to form a through hole in the sintering material in the axial direction.
The sintering mold also includes an upper punch fitted around the core rod and slidably inserted in the cavity of the die from an upper position, and a first lower punch loosely fitted to the core rod and slidably inserted in the cavity of the die from a lower position, to hold the sintering material together with the upper punch, to thereby form a flange portion on an end portion of the sintering material.
Further, the sintering mold includes a second lower punch slidably disposed between the first lower punch and the core rod, to form the other end portion of the sintering material.

The core rod, the upper punch, the first lower punch, and the second lower punch slide in the axial direction (hereinafter, "sliding direction of the sintering mold") in the molding and sintering process of the sintering material. Thus, the engaging recesses receding in the radial direction orthogonal to the sliding direction of the sintering mold are unable to be formed with sufficient accuracy. Consequently, the engaging recesses receding in the radial direction orthogonal to the axial direction of the compressor have to be formed in the molded and sintered product (sintered body) as post process, offsetting the reduction in processing cost achieved by employing the sintering material. [0010]
The present invention has been accomplished in view of the foregoing problem, and provides a sealed compressor that eliminates the need for post process despite employing a sintered body in a portion of a compression mechanism unit to be fixed to the sealed container, and that can be formed with high accuracy and at a lower cost, and a refrigeration cycle apparatus that includes such a sealed compressor. Solution to Problem [0011]
In one embodiment, the present invention provides a sealed compressor including a compression mechanism unit fixed inside a sealed container. The compression mechanism unit includes a flange portion clearance-fitted in the sealed container. The flange portion is formed of a sintered body and includes a fixing portion for engaging with the sealed container. The fixing portion has an engaging groove extending from one end face to a side of the other end face of the flange portion. The sealed container includes a protrusion fitted in the engaging groove. The engaging groove of the compression mechanism unit and the protrusion of the sealed container fix the compression mechanism unit and the sealed container to each other.
In another embodiment, the present invention provides a refrigeration cycle apparatus including the mentioned sealed compressor. Advantageous Effects of Invention

in the sealed compressor according to the present invention, the compression mechanism unit includes the flange portion clearance-fitted in the sealed container. The flange portion is formed of the sintered body and includes the engaging groove extending from one end face to the other end face of the flange portion. The sealed container includes the protrusion formed at the position corresponding to the engaging groove to be fitted in the engaging groove. The engaging groove of the compression mechanism unit and the protrusion of the sealed container constitute the fixing portion for fixing the compression mechanism unit and the sealed container to each other. The mentioned configuration allows the engaging groove for the fixing to be formed with high accuracy using the sintering mold, without post process. Consequently, an increase of the processing cost can be avoided and the manufacturing cost can be reduced. In addition, the refrigeration cycle apparatus according to the present invention includes the mentioned sealed compressor, and thus the cost of the apparatus as a whole can be reduced. Brief Description of Drawings [0013]
[Fig. 1] Fig. 1 is a vertical sectional view showing an overall configuration of a sealed compressor according to Embodiment 1 of the present invention.
[Fig. 2] Fig. 2 is a schematic view showing a configuration of a sintering mold for a sintered bearing.
[Fig. 3] Fig. 3 includes fragmentary cross-sectional views schematically illustrating a process of fixing a compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to a sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of engaging grooves.
[Fig. 4] Fig. 4 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to the sealed container, (a) shows a relationship between the engaging grooves and protrusions

after formation of the protrusions, and (b) shows the relationship between the engaging grooves and the protrusions after formation of the protrusions, viewed from a different angle from (a).
[Fig. 5] Fig. 5 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to the sealed container, (a) shows a tightening state due to cooling contraction after formation of the protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a).
[Fig. 6] Fig. 6 includes fragmentary cross-sectional views schematically illustrating a process of fixing a compression mechanism unit of a sealed compressor according to Embodiment 2 of the present invention to a sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of engaging grooves.
[Fig. 7] Fig. 7 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention to the sealed container, (a) shows a tightening state due to cooling contraction after formation of protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a).
[Fig. 8] Fig. 8 is a fragmentary cross-sectional view schematically illustrating a first variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.
[Fig. 9] Fig. 9 is a fragmentary cross-sectional view schematically illustrating a second variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.
[Fig. 10] Fig. 10 is a fragmentary cross-sectional view schematically illustrating a third variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.

[Fig. 11] Fig. 11 includes fragmentary cross-sectional views schematically illustrating a process of fixing a compression mechanism unit of a sealed compressor according to Embodiment 3 of the present invention to a sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of engaging grooves.
[Fig. 12] Fig. 12 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 3 of the present invention to the sealed container, (a) shows a tightening state due to cooling contraction after formation of protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a).
[Fig. 13] Fig. 13 is a diagram of a refrigerant circuit in a refrigeration cycle apparatus that includes a sealed compressor according to Embodiment 5 of the present invention. Description of Embodiments [0014] Embodiment 1
Fig. 1 is a vertical sectional view showing a general configuration of a sealed compressor according to Embodiment 1, for example, a two-cylinder sealed compressor provided with two cylinders.
As shown in Fig. 1, the sealed compressor 100 according to Embodiment 1, exemplified by the two-cylinder sealed compressor, includes a motor unit 200 having a stator 2 and a rotor 3 in a high-pressure atmosphere in a sealed container 1, and a compression mechanism unit 300 driven by the motor unit 200 via a crankshaft 4. In the bottom portion of the sealed container 1, refrigerating machine oil for lubricating a sliding portion of the compression mechanism unit 300 is stored. [0015]
The compression mechanism unit 300 is located in a lower section of the sealed container 1, and the motor unit 200 is located above the compression mechanism unit 300 in the sealed container 1.

The compression mechanism unit 300 sucks low-pressure refrigerant gas through suction pipes 40 and 41 connected to a low-pressure side of a refrigeration cycle via a suction muffler 20, and compresses the refrigerant gas. [0017]
High-pressure refrigerant gas discharged from the compression mechanism unit 300 passes through the motor unit 200 and is discharged to a high-pressure side of the refrigeration cycle through a discharge pipe 25. [0018]
A brushless DC motor in which the rotor 3 is formed of a permanent magnet is generally employed as the motor unit 200. Alternatively, an induction motor may be employed. [0019]
Power is supplied to the stator 2 of the motor unit 200 from a non-illustrated external power source through a glass terminal 26 and a lead wire 27. [0020]
The crankshaft 4 is fixed to the rotor 3 of the motor unit 200, and includes a spindle 4a supported by a main bearing 60, a countershaft 4b located on the opposite side of the spindle 4a and supported by a sub bearing 70, and eccentric shafts 4c and 4d formed with a predetermined phase difference (180 degrees, for example) between the spindle 4a and the countershaft 4b. [0021]
The main bearing 60 is formed of a sintering material and has a T-shaped cross-section. The main bearing 60 is fitted to the spindle 4a of the crankshaft 4 with a clearance for sliding, and rotatably supports the spindle 4a. In addition, the main bearing 60 closes one of openings (on the side of the motor unit) in the respective end portions of a first cylinder 8. The sintering material constituting the main bearing 60 is generally formed through (1) mixing material powder having a particle diameter of 10 urn to 100 UJTI, (2) molding, (3) sintering, and (4) quenching. In the sintering process of (3), heating the molded body at a temperature equal to or lower than the

melting point of the material powder promotes the diffusion bonding and alloying of the metal particles. The quenching process of (4) increases the surface hardness. [0022]
The sub bearing 70 has a T-shaped cross-section. The sub bearing 70 is fitted to the countershaft 4b of the crankshaft 4 with a clearance for sliding, and rotatably supports the countershaft 4b. In addition, the sub bearing 70 closes one of openings (on the side of the motor unit) in the respective end portions of a second cylinder 9. [0023]
The compression mechanism unit 300 includes, as described above, the first cylinder 8 located on the side of the spindle 4a and the second cylinder 9 located on the side of the countershaft 4b. [0024]
The first cylinder 8 has a cylindrical inner space, in which the eccentric shaft 4c of the crankshaft 4 and a first piston (also called rolling piston) 11 a rotatably fitted to the eccentric shaft 4c are accommodated, so that the rotation of the crankshaft 4 causes the first piston 11a to eccentrically rotate. The first cylinder 8 also includes a non-illustrated first vane that reciprocates, when the eccentric shaft 4c rotates, in a non-illustrated first vane groove in contact with the first piston 11a. The first vane reciprocates in the first vane groove to divide a space formed between the first cylinder 8 and the first piston 11a into a suction chamber and a compression chamber. The first vane groove is radially formed in the first cylinder 8 to penetrate through in the axial direction. [0025]
In the first cylinder 8 accommodating the first piston 11a and the first vane, the end portions of the inner space in the axial direction are closed by the main bearing 60 and the partition plate 10, and hence a sealed chamber 8a is defined in the first cylinder 8. The chamber 8a is divided by the first piston 11a and the first vane into the suction chamber and the compression chamber, in the rotating direction of the crankshaft 4.

The second cylinder 9 also has a cylindrical inner space, in which the eccentric shaft 4d of the crankshaft 4 and a second piston (also called rolling piston) 11 b rotatably fitted to the eccentric shaft 4d are accommodated, so that the rotation of the crankshaft 4 causes the second piston 11 b to eccentrically rotate. The second cylinder 9 also includes a non-illustrated second vane that reciprocates, when the eccentric shaft 4d rotates, in a non-illustrated second vane groove in contact with the second piston 11b. The second vane reciprocates in the second vane groove to divide a space formed between the second cylinder 9 and the second piston 11b into a suction chamber and a compression chamber. The second vane groove is radially formed in the second cylinder 9 to penetrate through in the axial direction. [0027]
In the second cylinder 9 accommodating the second piston 11 b and the second vane, the end portions of the inner space in the axial direction are closed by the sub bearing 70 and the partition plate 10, and hence a sealed chamber 9a is defined in the second cylinder 9. The chamber 9a is divided by the second piston 11 b and the second vane into the suction chamber and the compression chamber, in the rotating direction of the crankshaft 4. [0028]
The first vane and the second vane are press-contacted to the first piston 11a and the second piston 11b, with a non-illustrated biasing device. The compression mechanism unit 300 has the end portions supported by the main bearing 60 and the sub bearing 70 supporting the rotating motion. [0029]
The sealed container 1 and the compression mechanism unit 300 are fixed to each other via the main bearing 60. The main bearing 60 is formed of a sintered body, and includes engaging grooves 62 formed in the outer circumferential portion of a flange portion 61 to penetrate through the flange portion 61 from one end face (lower end face) to the other end face (upper end face) in the axial direction, in other words, to extend parallel to the axial direction of the spindle 4a.

In this example, the engaging grooves 62 are composed of a pair of engaging grooves 62a and 62b located close to each other. Hereinafter, a partial region of the outer circumferential portion of the main bearing, including a plurality (two in this example) of engaging grooves 62a and 62b and a portion located between the engaging grooves 62a and 62b will be referred to as "fixing portion". The fixing portion is formed, for example, at three positions at regular intervals in the outer circumferential portion of the flange portion 61 of the main bearing 60. Thus, the engaging grooves 62 include six grooves in total. [0031]
On the part of the sealed container 1, a pair of protrusions (container protrusions) 1a and 1b are formed on the inner wall, to fit in the engaging grooves 62a and 62b. [0032]
Fig. 2 is a schematic view showing a configuration of a sintering moid for the sintered bearing.
The sintering mold 500 includes a die 501, a core rod 502, an upper punch 503, a first lower punch 504, and a second lower punch 505, as shown in Fig. 2. [0033]
To be more detailed, the die 501 includes a cavity 501a in which a sintering material 600 is accommodated. [0034]
The core rod 502 is slidably disposed inside the cavity 501a of the die 501, to define a through hole 601 in the central portion of the sintering material 600, in the axial direction. [0035]
The upper punch 503 is fitted around the core rod 502 and slidably inserted in the cavity 501a of the die 501 from an upper position.

The first lower punch 504 is loosely fitted to the core rod 502 and slidably inserted in the cavity 501a of the die 501 from a lower position, to hold the sintering material 600 together with the upper punch 503, to thereby form a flange portion 602. [0037]
The second lower punch 505 is slidably disposed between the first lower punch 504 and the core rod 502, to form the other end portion 603 of the sintering material 600. [0038]
The core rod 502, the upper punch 503, the first lower punch 504, and the second lower punch 505 slide in the sliding direction of the sintering mold 500, in the molding and sintering process of the sintering material 600. A non-illustrated molding portion of the engaging groove 62 is integrally provided on one or both of the upper punch 503 and the first lower punch 504. [0039]
Thus, the sintering mold 500 is configured to slide in the axial direction, to press and sinter the sintering material 600 in the axial direction, while forming a hole for inserting the spindle 4a (through hole 601) in the central portion of the sintering material 600 to be formed into the main bearing 60. Thus, the sintering mold 500 is unable to form a transverse hole orthogonal to the axial direction, because of the structure of the sintering mold 500. However, in Embodiment 1, the engaging grooves 62 are formed in the outer circumferential portion of the flange portion 61 to penetrate from one end face (lower end face) to the other end face (upper end face) in the axial direction, and thus the extension direction of the engaging grooves 62 corresponds to the sliding direction of the sintering mold 500. Consequently, the engaging grooves 62 can be formed with the sintering mold 500, and thus the post process is unnecessary and no additional cost is incurred. [0040]
With reference to Fig. 3 to Fig. 5 and additionally with reference to Fig. 1 described above, a process of fixing the compression mechanism unit 300 in the sealed container 1 will be described.

Fig. 3 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to the sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of the engaging grooves. Fig. 4 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to the sealed container, (a) shows a relationship between the engaging grooves and the protrusions after formation of the protrusions, and (b) shows the relationship between the engaging grooves and the protrusions after formation of the protrusions, viewed from a different angle from (a). Fig. 5 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 1 of the present invention to the sealed container, (a) shows a tightening state due to cooling contraction after formation of the protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a). [0041]
In the sealed compressor 100 according to Embodiment 1, for example, the two-cylinder sealed compressor, the compression mechanism unit 300 is clearance-fitted to the sealed container 1, and more specifically, the compression mechanism unit 300 is fixed to the sealed container 1 via the main bearing 60. The terms "clearance-fitting" refers to fitting achieved in the case where the outer diameter of the compression mechanism unit 300 is smaller than the inner diameter of the sealed container 1, and hence no load is applied to the compression mechanism unit 300 from the sealed container 1, irrespective of the circularities of these components. In addition, the outer diameter or the inner diameter herein are referred to the average value of the outer diameter or the inner diameter measured at two locations orthogonal to each other, or three or more locations including the two orthogonal to each other and one or more other locations.

First, positions on the wall of the sealed container 1 corresponding to the fixing portions of the compression mechanism unit 300 are locally heated from outside, to thermally expand the sealed container 1. More specifically, as shown in Fig. 1 and Fig. 3, the position on the outer circumferential surface of the sealed container 1, corresponding to a portion 63 between the pair of engaging grooves 62a and 62b in each fixing portion of the main bearing 60 of the compression mechanism unit 300, is designated as center of heating, and the positions on the wall of the sealed container 1 opposing the fixing portions are locally heated from outside, to thermally expand the sealed container 1. [0043]
Then, a pair of pressing jigs 81A and 82A, each formed in a square column shape having a width equal to or slightly narrower than that of the engaging grooves 62a and 62b and having a flat distal end, are simultaneously pressed against the outer wall of the sealed container 1, from right above the pair of engaging grooves 62a and 62b as shown in Fig. 3. As result, a pair of protrusions (container protrusions) 1a and 1b are formed to be press-fitted into the engaging grooves 62a and 62b on the inner wail of the sealed container 1, as shown in Fig. 4. These protrusions are also called fastening points, and a plurality (two in this example) of closely located fastening points will hereinafter be referred to as "fastening portion". Three of such fastening portions are formed by simultaneously pressing the pressing jigs 81A and 82A against three positions on the outer circumferential portion of the compression mechanism unit 300. [0044]
Subsequently, when the thermally expanded sealed container 1 is cooled, the two protrusions 1a and 1b are attracted toward the center of heating owing to thermal contraction, as shown in Fig. 5. Thus, the portion 63 located in the middle between the engaging grooves 62a and 62b is tightly held (fastened) in the circumferential direction by the two protrusions 1a and 1b, so that the compression mechanism unit 300 is fixed to the sealed container 1. Such a fastening process is performed at

each of the three fixing portions provided at regular intervals on the outer circumferential portion of the flange portion 61 of the main bearing 60. [0045]
As described above, in the sealed compressor 100 according to Embodiment 1, for example, the two-cylinder sealed compressor, the compression mechanism unit 300 is fixed by tightly holding (fastening) with force exerted in the circumferential direction, instead of force exerted in the radiai direction utilized in the conventional welding or press-fitting process, and thus the compression mechanism unit 300 barely suffers distortion. In addition, as the sealed container 1 is not perforated, intrusion of foreign matters such as a spatter and leakage of refrigerant can be prevented. [0046]
Generaily, the sealed container 1 is formed of iron. The yield point of iron sharply drops from approximately 600 degrees Celsius. The temperature at which the yield point starts to sharply drop will hereinafter be referred to as "softening temperature". To reduce the rigidity of the sealed container 1, to reduce the force required for pressing the pressing jigs 81A and 82A to form the protrusions 1a and 1b, and to lower the yield point of the material constituting the sealed container 1, to thereby facilitating the protrusions 1a and 1b to be efficiently formed, the heating temperature is preferred to be equal to or higher than the softening temperature and lower than the melting point of the material. For reference, the melting point of iron is 1,560 degrees Celsius. [0047]
In the sealed compressor according to Embodiment 1, for example, the two-cylinder sealed compressor, the yield point is lowered by the heating. Consequently, spring back of the sealed container 1 in the radial direction (in this case, restoration of the protrusions 1a and 1b) can be minimized after the plastic deformation of the sealed container 1 (in this case, formation of the protrusions 1a and 1b), and a predetermined pressing depth can be efficiently and surely secured. The pressing depth refers to the depth by which the protrusions 1a and 1b intrude in the engaging

grooves 62a and 62b, indicated by H in Fig. 5 (a). As described above, the sealed container 1 is formed of iron, the softening temperature of iron is 600 degrees Celsius, and the melting point of iron is 1,560 degrees Celsius. Thus, the temperature for the local heating is preferred to be in a range between 600 degrees Celsius and 1,500 degrees Celsius. Naturally, when the material is other than iron, the heating temperature should be set to a different range, equal to or higher than the softening temperature and lower than the melting point of the selected material. [0048]
Setting the heating region on the sealed container 1 to include the entirety of the portion where the pressing jigs 81A and 82Aare applied allows the protrusions 1a and 1b to be surely formed using the high-temperature characteristics of the material of the sealed container 1, and allows the pressing force required for the formation of the protrusions 1a and 1b to be reduced, thereby minimizing the distortion that the compression mechanism unit 300 may suffer in the assembly process. Further, setting the center of heating of the sealed container 1 to the position corresponding to the center between the pair of engaging grooves 62a and 62b (portion 63) allows the protrusions 1a and 1b to thermally contract toward the center of heating due to the cooling after the formation of the protrusions 1a and 1b on the sealed container 1. Consequently, the two closely located protrusions 1a and 1b of the sealed container 1 firmly hold the portion 63 located between the engaging grooves 62a and 62b of the compression mechanism unit 300. [0049]
As described above, the pressing force required for the formation of the protrusions 1a and 1b on the sealed container 1 can be reduced, and the portion 63 located between the engaging grooves 62a and 62b of the compression mechanism unit 300 can be firmly held. Consequently, the compression mechanism unit 300 can be firmly fixed to the sealed container 1. Thus, even when the compression mechanism unit 300 is clearance-fitted to the sealed container 1, the compression mechanism unit 300 can withstand, over a long period of use of the sealed

compressor, the normal force applied during the operation, as well as excessive force
applied in the event of malfunction, thereby remaining free from backlash.
[0050]
Further, by adopting the clearance-fitting, the compression mechanism unit 300 can be exempted from suffering the pressing force in the radial direction, to be applied after the fixing in the case of the conventional welding or press-fitting process. Consequently, the distortion of the compression mechanism unit 300 can be minimized, and resultantly the performance of the sealed compressor can be improved. [0051]
In Embodiment 1, in the axial direction of the sealed compressor, the compression mechanism unit 300 is supported by being held by the protrusions 1a and 1b of the sealed container 1, as shown in Fig. 5 (a) and Fig. 5 (b). In the direction of the tangent, the compression mechanism unit 300 is supported by being held by the protrusions 1a and 1b of the sealed container 1, as well as by the rigidity of the protrusions 1a and 1b of the sealed container 1. Thus, the fixing shape may be selected to secure the fixing strength required for withstanding the acceleration applied to the fixing portion. The fixing strength can be increased, for example, by increasing the cross-sectional area of the protrusions 1a and 1b, or increasing the number of fixing portions. [0052] Embodiment 2
Fig. 6 includes fragmentary cross-sectional views schematically illustrating a process of fixing a compression mechanism unit of a sealed compressor according to Embodiment 2 of the present invention to a sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of engaging grooves. Fig. 7 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention to the sealed container, (a) shows a tightening state due to cooling contraction after formation of

protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a). In these drawings, the same elements as those of Embodiment 1 are given the same reference signs. For general description, Fig. 1 and Fig. 2 will be referred to.
In the sealed compressor according to Embodiment 2, engaging grooves 62c and 62d are formed as stopped grooves not formed to penetrate in the axial direction, on the outer circumferential portion of the flange portion 61 of the main bearing 60, constituting the fitting portion, as shown in Fig. 6 and Fig. 7. The engaging grooves 62c and 62d are formed to extend in the axial direction from the respective end portions of the flange portion 61, with a spacing from each other in the circumferential direction.
Pressing jigs 81B and 82B are each formed in a circular column shape having a width equal to or slightly narrower than that of the engaging grooves 62c and 62d, and having a flat distal end. The configuration of the remaining portions and the manufacturing process of the sintered bearing using the sintering mold 500 are the same as those of Embodiment 1, and hence the description will be omitted. [0053]
In the sealed compressor according to Embodiment 2, the engaging grooves 62c and 62d are stopped grooves formed in the outer circumferential portion of the flange portion 61 of the main bearing 60, to extend in the axial direction from the respective end portions of the flange portion 61, with a spacing from each other in the circumferential direction. Consequently, the engaging grooves 62c and 62d can be formed with the sintering mold 500, and thus the post process is unnecessary and no additional cost is incurred. [0054]
In addition, forming the engaging grooves 62c and 62d as stopped grooves oriented in the opposite directions allows the compression mechanism unit to be supported in the axial direction, not only by being held by the protrusions 1c and 1d of the sealed container 1 formed by the pressing jigs 81B and 82B, but also by the rigidity of the protrusions 1c and 1d of the sealed container 1, as shown in Fig. 7.

The shape of the end portion of the stopped groove is not specifically limited and may be, for example, square or circular. The cross-sectional shape of the protrusions 1c and 1d of the sealed container 1 is not specifically limited, and may be any shape as long as the cross-sectional area secures necessary fixing strength. [0056]
Further, the stopped grooves do not have be spaced from each other in the circumferential direction and oriented in opposite directions like the engaging grooves 62c and 62d according to Embodiment 2. A first to a third variations described below may be adopted. [0057]
Fig. 8 is a fragmentary cross-sectional view schematically illustrating the first variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.
The first variation represents two closely located engaging grooves (stopped grooves) 62e and 62f oriented in the same direction (axial direction), and each formed in the outer circumferential portion of the flange portion 61 of the main bearing 60, constituting the fitting portion, to extend in the axial direction from one end face of the flange portion 61. [0058]
For the engaging groove shape of the first variation, the forming section of the engaging grooves 62e and 62f is only required to be on either of the upper punch 503 and the first lower punch 504 of the sintering mold 500, and thus the production of the sintering mold 500 can be simplified. [0059]
Fig. 9 is a fragmentary cross-sectional view schematicaily illustrating the second variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.
The second variation represents two closely located engaging grooves (stopped grooves) 62g and 62h oriented in the same direction (axial direction), and

each formed in the outer circumferential portion of the flange portion 61 of the main bearing 60, constituting the fitting portion, to extend in the axial direction from the other end face of the flange portion 61. [0060]
For the engaging groove shape of the second variation, the forming section of the engaging grooves 62g and 62h is only required to be on either of the first lower punch 504 and the upper punch 503 of the sintering mold 500, and thus the production of the sintering mold 500 can be simplified. [0061]
Fig. 10 is a fragmentary cross-sectional view schematically illustrating the third variation of shapes of the engaging grooves of the compression mechanism unit of the sealed compressor according to Embodiment 2 of the present invention.
The third variation represents two closely located engaging grooves (stopped grooves) 62i and 62j coaxially formed to oppose each other, on the outer circumferential portion of the flange portion 61 of the main bearing 60, constituting the fitting portion, to extend from the respective end faces of the flange portion 61. [0062]
With the engaging groove shape of the third variation, as the engaging grooves 62i and 62j are coaxially arranged, the pressing jigs 81B and 82B can be arranged along a linear surface instead of a curved surface. Thus, the production of the pressing jigs 81B and 82B can be simplified. [0063] Embodiment 3
Fig. 11 includes fragmentary cross-sectional views schematically illustrating a process of fixing a compression mechanism unit of a sealed compressor according, to Embodiment 3 of the present invention to a sealed container, (a) shows pressing jigs, (b) shows heating positions before the pressing, and (c) shows shapes of engaging grooves. Fig. 12 includes fragmentary cross-sectional views schematically illustrating a process of fixing the compression mechanism unit of the sealed compressor according to Embodiment 3 of the present invention to the sealed

container, (a) shows a tightening state due to cooling contraction after formation of protrusions, and (b) shows the tightening state due to cooling contraction after formation of the protrusions, viewed from a different angle from (a). In these drawings, the same elements as those of Embodiment 1 are given the same reference signs. For general description, Fig. 1 and Fig. 2 will be referred to.
In the sealed compressor according to Embodiment 3, engaging grooves 62k and 62I are formed to penetrate and to incline from the axial direction, as shown in Fig. 11 and Fig. 12.
Pressing jigs 81C and 82C are each formed in a square column shape having a width equal to or slightly narrower than that of the engaging grooves 62k and 62I, and having a flat distal end. The configuration of the remaining portions is the same as those of Embodiment 1. [0064]
The engaging grooves 62k and 621 formed to penetrate and to incline from the axial direction, provided in the sealed compressor according to Embodiment 3, can be formed with the sintering mold 500, by arranging the upper punch 503 or the first lower punch 504 having the forming section of the engaging grooves 62k and 62I that are rotatable, not only slidable. Thus, the post process is unnecessary and no additional cost is incurred. [0065]
As the engaging grooves 62k and 62I in the sealed compressor according to Embodiment 3 are formed to penetrate and to incline from the axial direction, the compression mechanism unit can be supported in the axial direction, not only by being held by the protrusions of the sealed container 1, but also by the rigidity of the protrusions 1e and 1f of the sealed container 1, depending on the inclination angle, as shown in Fig. 12. [0066]
Although the configurations in which the compression mechanism unit 300 is fixed to the sealed container 1 via the main bearing 60 have been described above, the compression mechanism unit 300 may be fixed to the sealed container 1 via

another component of the compression mechanism unit 300 such as the first cylinder 8, the second cylinder 9, the partition plate 10, and the sub bearing 70. In such cases also, the advantageous effects provided by the foregoing embodiments can equally be achieved. [0067] Embodiment 4
According to Embodiments 1 to 3, the components for fixing the compression mechanism unit 300 to the sealed container 1 are formed of the sintered body and having a pair of closely located engaging grooves, so that the compression mechanism unit 300 is clearance-fitted to the sealed container 1 and, after heating the sealed container 1, a pair of pressing jigs are simultaneously pressed against the outer wall of the sealed container 1 at two points, from right above the pair of engaging grooves. However, the present invention is not limited to the mentioned configuration. For example, only a single engaging groove may be provided at each of the fixing portions, and a single pressing jig may be pressed against the outer wail of the sealed container 1 to fix the compression mechanism unit 300. In the case of cold pressing without the heating of the sealed container 1, greater pressing force is required because the pressing jig is pressed while the sealed container 1 maintains its original rigidity. In the case of the pressing after the heating of the sealed container 1, the pressing force required for forming the protrusion can be reduced compared with the case of the cold pressing; however, the sealed container 1 thermally contracts after the pressing and fixing to cause a slight backlash between the compression mechanism unit 300 and the protrusion of the sealed container 1. To prevent such backlash, the compression mechanism unit 300 may be interference-fitted to the sealed container 1. In this case, the compression mechanism unit 300 is subjected to force in the radial direction, and hence the rigidity of the compression mechanism unit 300 is required to increase, because the increased rigidity can minimizes the distortion of the compression mechanism unit 300. [0068] Embodiment 5

Fig. 13 is a diagram of a refrigerant circuit in a refrigeration cycle apparatus, such as an air-conditioning apparatus, that includes the sealed compressor according to Embodiment 5 of the present invention. In Fig. 13, the same elements as those of Embodiment 1 are given the same reference signs.
The refrigeration cycle apparatus according to Embodiment 5, for example, an air-conditioning apparatus 400 includes, as shown in Fig. 13, the sealed compressor 100 according to Embodiment 1, a four-way valve 131 that switches the flow of refrigerant from the sealed compressor 100, an outdoor side heat exchanger 132, a pressure reducing device 133 such as an electronic expansion valve, an indoor side heat exchanger 134, an accumulator 135 connected to the suction-side pipe of the sealed compressor 100 to store the refrigerant, and a suction muffler 20, and the mentioned components are sequentially connected via a pipe. [0069]
Operations of the refrigeration cycle apparatus, for example, the air-conditioning apparatus 400 configured as above, will be described below, in the order of a heating operation and a cooling operation.
When the heating operation is started, the four-way valve 131 is set for connection indicated by solid lines in Fig. 13. Subsequently, high-temperature, high-pressure refrigerant compressed by the sealed compressor 100 flows to the indoor side heat exchanger 134 to be condensed and liquefied, and is then expanded by the pressure reducing device 133 to turn into low-temperature, low-pressure two-phase refrigerant. Then, the refrigerant flows to the outdoor side heat exchanger 132 to be evaporated and gasified, and returns to the sealed compressor 100 through the four-way valve 131, the accumulator 135, and the suction muffler 20. In other words, the refrigerant circulates as indicated by solid-line arrows in Fig. 13. [0070]
The cooling operation will be described below. When the cooling operation is started, the four-way valve 131 is set for connection indicated by broken lines in Fig. 13. Subsequently, high-temperature, high-pressure refrigerant compressed by the sealed compressor 100 flows to the outdoor side heat exchanger 132 to be

condensed and liquefied, and is then expanded by the pressure reducing device 133 to turn into low-temperature, low-pressure two-phase refrigerant. Then, the refrigerant flows to the indoor side heat exchanger 134 to be evaporated and gasified, and returns to the sealed compressor 100 through the four-way valve 131, the accumulator 135, and the suction muffler 20. In other words, when the operation is switched from the heating operation to the cooling operation, the indoor side heat exchanger 134 turns into an evaporator from a condenser, and the outdoor side heat exchanger 132 turns into a condenser from an evaporator, so that the refrigerant circulates as indicated by broken-line arrows in Fig. 13. [0071]
As the refrigeration cycle apparatus according to Embodiment 5, for example, the air-conditioning apparatus 400, employs the sealed compressor 100 according to Embodiment 1 as the sealed compressor, the cost of the apparatus as a whole can be reduced. Reference Signs List [0072]
1: sealed container, 1a, 1b, 1c, 1d, 1e, 1f: protrusion, 2: stator, 3: rotor, 4: crankshaft, 4a: spindle, 4b: countershaft, 4c, 4d: eccentric shaft, 8: first cylinder, 8a: chamber, 9: second cylinder, 9a: chamber, 10: partition plate, 11a: first piston, 11b: second piston, 20: suction muffler, 25: discharge pipe, 26: glass terminal, 27: lead wire, 40, 41: suction pipe, 60: main bearing (fitting portion), 61: flange portion, 62, 62a, 62b, 62c, 62d, 62e, 62f, 62g, 62h, 62i, 62j, 62k, 621: engaging groove, 63: portion, 70: sub bearing, 81A, 82A, 81B, 82B, 81C, 82C: pressing jig, 100: sealed compressor, 131: four-way valve, 132: outdoor side heat exchanger, 133: pressure reducing device, 134: indoor side heat exchanger, 135: accumulator, 200: motor unit, 300: compression mechanism unit, 400: air-conditioning apparatus (refrigeration cycle apparatus), 500: sintering mold, 501: die, 501a: cavity, 502: core rod, 503: upper punch, 504: first lower punch, 505: second lower punch, 600: sintering material, 601: through hole, 602: flange portion, 603: other end portion

CLAIMS
[Claim 1]
A sealed compressor comprising a compression mechanism unit fixed inside a sealed container,
the compression mechanism unit including a flange portion clearance-fitted in the sealed container,
the flange portion being formed of a sintered body, and including a fixing portion for engaging with the sealed container,
the fixing portion having an engaging groove extending from one end face to a side of an other end face of the flange portion,
the sealed container including a protrusion fitted in the engaging groove,
the engaging groove of the compression mechanism unit and the protrusion of the sealed container fixing the compression mechanism unit and the sealed container to each other. [Claim 2]
The sealed compressor of claim 1, wherein a plurality of the engaging grooves constitute a set, and one or more sets of the engaging grooves are provided in the flange portion. [Claim 3]
The sealed compressor of claim 1 or 2, wherein the protrusion of the sealed container is formed on an inner circumferential surface of the sealed container, the protrusion being formed of a portion of the sealed container opposing the engaging groove pressed toward a bottom portion of the engaging groove while the portion of the sealed container opposing the engaging groove is heated. [Claim 4]
The sealed compressor of claim 3, wherein a temperature for heating the portion of the sealed container opposing the engaging groove is equal to or higher than a softening temperature and lower than a melting point of a material constituting the sealed container. [Claim 5]

A sealed compressor comprising a compression mechanism unit fixed inside a sealed container,
the compression mechanism unit including a flange portion interference-fitted in the sealed container,
the flange portion being formed of a sintered body, and including a fixing portion for engaging with the sealed container,
the fixing portion having an engaging groove extending from one end face to a side of an other end face of the flange portion,
the sealed container including a protrusion fitted in the engaging groove, the protrusion being formed at a position opposing the engaging groove,
the engaging groove of the compression mechanism unit and the protrusion of the sealed container fixing the compression mechanism unit and the sealed container to each other. [Claim 6]
The sealed compressor of claim 5, wherein a plurality of the engaging grooves constitute a set, and one or more sets of the engaging grooves are provided in the flange portion. [Claim 7]
The sealed compressor of claim 5 or 6, wherein the protrusion of the sealed container is formed on an inner circumferential surface of the sealed container, the protrusion being formed of a portion of the sealed container opposing the engaging groove pressed toward a bottom portion of the engaging groove while the portion of the sealed container opposing the engaging groove is heated. [Claim 8]
The sealed compressor of claim 7, wherein a temperature for heating the portion of the sealed container opposing the engaging groove is equal to or higher than a softening temperature and lower than a melting point of a material constituting the sealed container. [Claim 9]

The sealed compressor of any one of claims 1 to 8, wherein the engaging groove of the compression mechanism unit comprises a through groove formed in a direction parallel to an axial direction of the compression mechanism unit. [Claim 10]
The sealed compressor of any one of claims 1 to 8, wherein the engaging groove of the compression mechanism unit comprises a stopped groove formed in a direction parallel to an axial direction of the compression mechanism unit. [Claim 11]
The sealed compressor of any one of claims 1 to 8, wherein the engaging groove of the compression mechanism unit comprises a through groove formed in a direction inclined from an axial direction of the compression mechanism unit. [Claim 12]
The sealed compressor of any one of claims 1 to 8, wherein the engaging groove of the compression mechanism unit comprises a stopped groove formed from each of end faces of the flange portion. [Claim 13]
The sealed compressor of any one of claims 1 to 8, wherein the engaging groove of the compression mechanism unit comprises a stopped groove formed from each of end faces of the flange portion, the stopped grooves coaxially opposing each other. [Claim 14]
A refrigeration cycle apparatus comprising the sealed compressor of any one of claims 1 to 13.