Patent Publication Number: US-2021190072-A1

Title: Rotary compressor and refrigeration cycle apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of POT Application No. PCT/JP2018/034269, filed Sep. 14, 2013, the entire contents of which are incorporated herein by reference. 
     Embodiments described herein relate generally to a multi-cylinder rotary compressor and a refrigeration cycle apparatus comprising the rotary compressor. 
    
    
     BACKGROUND 
     In recent years, a three-cylinder rotary compressor having three sets of refrigerant compression units arranged in the axial direction of a rotating shaft has been developed in order to increase the refrigerant compression capacity. Three sets of refrigerant compression units are interposed between a pair of bearings that support the rotating shaft, and a partition plate is provided between the refrigerant compression units adjacent to each other in the axial direction of the rotating shaft. 
     Furthermore, each of three sets of refrigerant compression units includes a cylinder chamber through which the rotating shaft penetrates. The cylinder chamber is partitioned in the axial direction of the rotating shaft by the partition plate and the end plates of the pair of bearings, and rollers are accommodated in each cylinder chamber. The roller eccentrically rotates in the cylinder chamber, integrally with the rotating shaft, to compress the refrigerant sucked into the cylinder chamber. 
     The refrigerant compressed in the cylinder chamber is discharged to the outside of the refrigerant compression unit through each discharge port. However, according to the conventional three-cylinder rotary compressor, particularly, securing the capacity of the discharge passage communicating with the cylinder chamber located in the middle is difficult since only one discharge port is present for each cylinder chamber. 
     As a result, the discharge loss and discharge pressure pulsation of the refrigerant discharged from the intermediate cylinder chamber cannot be sufficiently reduced, and room for improvement of the performance of the rotary compressor or improvement for noise suppression during operation of the rotary compressor is left. 
     Embodiments described herein aim to obtain a rotary compressor capable of suppressing the discharge loss and discharge pulsation of the working fluid discharged from all the cylinder chambers to a low level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram schematically showing a configuration of a refrigeration cycle apparatus according to a first embodiment. 
         FIG. 2  is a cross-sectional view of a three-cylinder rotary compressor according to the first embodiment. 
         FIG. 3  is an enlarged cross-sectional view showing a compression mechanism unit of the three-cylinder rotary compressor in the first embodiment. 
         FIG. 4  is a cross-sectional view showing a positional relationship between a roller and a vane in a first cylinder chamber in the first embodiment. 
         FIG. 5  is an enlarged cross-sectional view showing a three-cylinder rotary compressor according to a second embodiment. 
         FIG. 6  is an enlarged cross-sectional view showing a three-cylinder rotary compressor according to a three embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, the rotary compressor comprises a sealed container, a compression mechanism unit that compresses a working fluid inside the sealed container, and a drive source that is accommodated in the sealed container and drives the compression mechanism unit. 
     The compression mechanism unit includes a rotating shaft connected to the drive source inside the sealed container, a first bearing and a second bearing rotatably supporting the rotating shaft and including end plates extending in a radial direction of the rotating shaft, a first muffler chamber attached to the first bearing, a second muffler chamber attached to the second bearing, at least three cylinder bodies interposed between the first bearing and the second bearing, and spaced apart and arranged in an axial direction of the rotating shaft, each defining a cylinder chamber, a plurality of partition plates provided between the adjacent cylinder bodies, and a plurality of rollers fitted in the rotating shaft to compress the working fluid in the cylinder chambers, and the cylinder chambers of the at least three cylinder bodies are partitioned in an axial direction of the rotating shaft by the end plate of the first bearing, the end plate of the second bearing, and the partition plates. 
     Each of the end plate of the first bearing and the end plate of the second bearing includes a first discharge port discharging the working fluid compressed in the cylinder chamber of the cylinder body adjacent to the end plate to the first muffler chamber and the second muffler chamber, and each of the plurality of partition plates that sandwich the intermediate cylinder body located between the two cylinder bodies adjacent to the end plates includes an intermediate muffler chamber in which the working fluid flows, and a second discharge port discharging the working fluid compressed in the cylinder chamber of the intermediate cylinder body to the intermediate muffler chamber. 
     First Embodiment 
     A first embodiment will be described hereinafter with reference to  FIGS. 1 to 4 . 
       FIG. 1  is a refrigeration cycle circuit diagram of an air conditioner  1 , which is an example of a refrigeration cycle apparatus. An air conditioner  1  comprises a rotary compressor  2 , a four-way valve  3 , an outdoor heat exchanger  4 , an expansion device  5 , and an indoor heat exchanger  6  as main elements. The plurality of elements constituting the air conditioner  1  are connected via a circulation circuit  4  in which a refrigerant serving as a working fluid circulates. 
     More specifically, as shown in  FIG. 1 , the discharge side of the rotary compressor  2  is connected to a first port  3   a  of the four-way valve  3 . A second port  3   b  of the four-way valve  3  is connected to the outdoor heat exchanger  4 . The outdoor heat exchanger  4  is connected to the indoor heat exchanger  6  via the expansion device  5 . The indoor neat exchanger  6  is connected to a third port  3   c  of the four-way valve  3 . A fourth port  3   d  of the four-way valve  3  is connected to an accumulator  8  which is the suction side of the rotary compressor  2 . 
     When the air conditioner  1  operates in the cooling mode, the four-way valve  3  is switched such that the first port  3   a  communicates with the second port  3   b  and the third port  3   c  communicates with the fourth port  3   d . When the operation of the air conditioner  1  is started in the cooling mode, a high-temperature and high-pressure vapor-phase refrigerant compressed by the rotary compressor  2  is guided to the outdoor heat exchanger  4  that functions as a radiator (condenser) through the four-way valve  3 . 
     The vapor-phase refrigerant guided to the outdoor heat exchanger  4  is condensed by heat exchange with air and changed to a high-pressure liquid-phase refrigerant. The high-pressure liquid-phase refrigerant is decompressed in the process of passing through the expansion device  5  and changes to a low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is guided to the indoor heat exchanger  6  that functions as a heat absorber (evaporator), and exchanges heat with air in the process of passing through the indoor heat exchanger  6 . 
     As a result, the gas-liquid two-phase refrigerant takes heat from the air and evaporates, and changes to a low-temperature and low-pressure vapor-phase refrigerant. The air passing through the indoor heat exchanger  6  is cooled by latent heat of vaporization of the liquid-phase refrigerant, becomes cola air, and is sent to a place to be air-conditioned (cooled). 
     The low-temperature and low-pressure vapor-phase refrigerant that has passed through the indoor heat exchanger  6  is guided to the accumulator  3  via the four-way valve  3 . When the liquid-phase refrigerant that cannot be completely evaporated is mixed in the refrigerant, the liquid-phase refrigerant is separated into the liquid-phase refrigerant and the vapor-phase refrigerant by the accumulator  8 . The low-temperature and low-pressure vapor-phase refrigerant from which the liquid-phase refrigerant is separated is sucked into the compression mechanism unit of the rotary compressor  2 , and is compressed again into the high-temperature and high-pressure vapor-phase refrigerant by the rotary compressor  2  and discharged to the circulation circuit  7 . 
     In contrast, when the air conditioner  1  operates in the heating mode, the four-way valve  3  is switched such that the first port  3   a  communicates with the third port  3   c  and the second port  3   b  communicates with the fourth port  3   d . For this reason, the high-temperature and high-pressure vapor-phase refrigerant discharged from the rotary compressor  2  is guided to the indoor heat exchanger  6  via the four-way valve  3  and exchanges heat with the air passing through the indoor neat exchanger  6 . That is, the indoor heat exchanger  6  functions as a condenser. 
     As a result, the vapor-phase refrigerant passing through the indoor heat exchanger  6  is condensed by heat exchange with air and changed to a high-pressure liquid-phase refrigerant. The air passing through the indoor heat exchanger  6  is heated by heat exchange with the vapor-phase refrigerant, becomes warm air, and is sent to a place to be air-conditioned (heated). 
     The nigh-temperature liquid-phase refrigerant that has passed through the indoor heat exchanger  6  is guided to the expansion device  5 , and is decompressed in the process of passing through the expansion device  5  to change to a low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant is guided to the outdoor heat exchanger  4  that functions as an evaporator, and evaporates by exchanging heat with air and changes to a low-temperature and low-pressure vapor-phase refrigerant. The low-temperature and low-pressure vapor-phase refrigerant that has passed through the outdoor heat exchanger  4  is guided to the accumulator S of the rotary compressor  2  via the four-way valve  3 . 
     Next, a specific configuration of the rotary compressor  2  will be described with reference to  FIGS. 2 to 4 .  FIG. 2  is a cross-sectional view showing the vertical three-cylinder rotary compressor  2 . As shown in  FIG. 2 , the three-cylinder rotary compressor  2  comprises a sealed container  10 , an electric motor  11 , and a compression mechanism unit  12  as main elements. 
     The sealed container  10  includes a cylindrical peripheral wall  10   a  and is erected along the vertical direction. Lubricating oil is stored inside a sealed container  10   a . A discharge pipe  10   b  is provided at an upper end of the sealed container  10 . The discharge pipe  10   b  is connected to the first port  3   a  of the four-way valve  3  via the circulation circuit  7 . 
     The electric motor  11  is an example of a drive source, and is accommodated in an intermediate part of the sealed container  10  along the axial direction so as to be located above a liquid level S of the lubricating oil. The electric motor  11  is a so-called inner rotor type motor and comprises a stator  13  and a rotor  14 . The stator  13  is fixed to an inner surface of the peripheral wall  10   a  of the sealed container  10 . The rotor  14  is surrounded by the stator  13 . 
     The compression mechanism unit  12  is accommodated in the lower part of the sealed container  10  so as to be immersed in the lubricating oil. As shown in  FIGS. 2 and 3 , the compression mechanism unit  12  comprises as main elements a rotating shaft  15 , a first refrigerant compression unit  16 A, a second refrigerant compression unit  16 B, a third refrigerant compression unit  16 C, a first partition plate  17 , a second partition plate  18 , a first bearing  19 , and a second bearing  20 . 
     The rotating shaft  15  has a straight central axis O 1  that is erected along the axial direction of the sealed container  10 . The rotating shaft  15  includes a first journal portion  24   a  located at the upper part, a second journal portion  24   b  located at the lower end part, first to third crank portions  23   a ,  23   b , and  23   c , and a first intermediate shaft portion  25  and a second intermediate shaft portion  26  located between the first journal portion  24   a  and the second journal portion  24   b . The first journal portion  24   a , the second journal portion  24   b , the first intermediate shaft portion  25 , and the second intermediate shaft portion  26  are coaxially located on the central axis O 1  of the rotating shaft  15 . The rotor  14  of the electric motor  11  is connected to an upper end of the first journal portion  24   a.    
     The first to third crank portions  23   a ,  23   b , and  23   c  are located between the first journal portion  24   a  and the second, journal portion  24   b . The first, to third, crank portions  23   a ,  23   b , and  23   c  are disk-shaped elements each having a circular cross-section, and are arranged at intervals in the axial direction of the rotating shaft  15 . 
     Furthermore, the first to third crank portions  23   a ,  23   b , and  23   c  are eccentric with respect to the central axis O 1  of the rotating shaft  15 . That is, the eccentric directions of the first to third crank portions  23   a ,  23   b , and  23   c  with respect to the central axis O 1  are deviated by, for example, 120° in the circumferential direction of the rotating shaft  15 . 
     The first intermediate shaft portion  25  is located between the first crank portion  23   a  and the second crank portion  23   b  on the central axis O 1 . The second intermediate shaft portion  26  is located between the second crank portion  23   b  and the third crank portion  23   c  on the central axis O 1 . 
     Furthermore, the second intermediate shaft portion  26  includes a third journal portion  27 . The third journal portion  27  is a disk-shaped element having a circular cross-section, and is located coaxially with the central axis O 1  of the rotating shaft  15 . The third journal portion  27  has an outer diameter larger than that of the other portions of the second intermediate shaft portion  26 , and is provided at a position offset to the side of the second crank portion  23   b  with respect to the third crank portion  23   c.    
     As shown in  FIGS. 2 and 3 , the first to third refrigerant compression units  16 A,  16 B, and  16 C are arranged in a row at intervals, in the axial direction of the rotating shaft  15 , inside the sealed container  10 . The first to third refrigerant compression units  16 A,  163 , and  16 C include a first cylinder body  29   a , a second cylinder body  29   b , and a third cylinder body  29   c , respectively. The first to third cylinder bodies  29   a ,  29   b , and  29   c  are set to have, for example, the same thickness along the axial direction of the rotating shaft  15 . 
     According to the present embodiment, the first crank portion  23   a  of the rotating shaft  15  is located  29   a . The second crank portion  23   b  of the rotating shaft  15  is located at an inner diameter part of the second cylinder body  29   b . The third crank portion  23   c  of the rotating shaft  15  is located at an inner diameter part of the third cylinder body  29   c.    
     As shown in  FIG. 3 , the first partition plate  17  is interposed between the first cylinder body  29   a  and the second cylinder body  29   b . An upper surface of the first partition plate  17  is in contact with a lower surface of the first cylinder body  29   a  so as to cover the inner diameter part of the first cylinder body  29   a  from below. A lower surface of the first partition plate  17  is in contact with an upper surface of the second cylinder body  29   b  so as to cover the inner diameter part or the second cylinder body  29   b  from above. 
     Furthermore, a circular through hole  30  is formed in a central part of the first partition plate  17 . The through hole  30  is located between the inner diameter part of the first cylinder body  29   a  and the inner diameter part of the second cylinder body  29   b , and the first intermediate shaft portion  25  of the rotating shaft  15  penetrates the through hole  30 . 
     According to the present embodiment, the first partition plate  17  is divided into a pair of disk-shaped plate elements  31   a  and  31   b . The plate elements  31   a  and  31   b  are overlaid on each other in the axial direction of the rotating shaft  15 . The axial direction of the rotating shaft  15  can be rephrased as the thickness direction of the plate elements  31   a  and  31   b . One of the plate elements, i.e., the plate element  31   a  is in contact with the upper surface of the second cylinder body  29   b . The other plate element, i.e., the plate element  31   b  is in contact with the lower surface of the first cylinder body  29   a.    
     The second partition plate  13  is interposed between the second cylinder body  29   b  and the third cylinder body  29   c . The upper surface of the second partition plate  13  is in contact with the lower surface of the second cylinder body  29   b  so as to cover the inner diameter part of the second cylinder body  29   b  from below. The lower surface of the second partition plate  18  is in contact with the upper surface of the third cylinder body  21   c  so as to cover the inner diameter part of the third cylinder body  21   c  from above. 
     According to the present embodiment, a thickness dimension T 2  of the second partition plate  18  is larger than a thickness dimension T 1  of the first partition plate  17 . Furthermore, the second partition plate  13  is divided into a pair of disk-shaped plate elements  32   a  and  32   b . The plate elements  32   a  and  32   b  are overlaid on each other in the axial direction of the rotating shaft  15 . The axial direction of the rotating shaft  15  can be rephrased as the thickness direction of the plate elements  32   a  and  32   b . One of the plate elements, i.e., the plate element  32   a  is in contact with the lower surface of the second cylinder body  29   b . The other plate element, i.e., the plate element  32   b  is in contact with the upper surface of the third cylinder body  29   c.    
     According to the present embodiment, the plate element  32   a  of the second partition plate  18  is formed to be thicker than the plate element  32   b . As shown in  FIG. 3 , a circular bearing hole  33  is provided in the central part of the plate element  32   a . A circular communication hole  34  is provided in the central part of the plate element  32   b  of the second partition plate  18 . The communication hole  34  has a diameter larger than the bearing hole  33  and is made to coaxially communicate with the bearing hole  33 . 
     The bearing hole  33  and the communication hole  34  are located between the inner diameter part of the second cylinder body  29   b  and the inner diameter part of the third cylinder body  29   c , and the second intermediate shaft portion  26  of the rotating shaft  15  penetrates the bearing hole  33  and the communication hole  34 . 
     The third journal portion  27  provided in the second intermediate shaft portion  26  is slidably fitted in the bearing hole  33  of the second partition plate  18  in the axial direction. By this fitting, the second partition plate  18  also functions as a third bearing that supports the rotating shaft  15  between the second cylinder body  29   b  and the third cylinder body  29   c.    
     As shown in  FIGS. 2 and 3 , the first bearing  19  is arranged on the first cylinder body  29   a . The first bearing  19  includes a tubular bearing body  36  that rotatably supports the first journal portion  24   a  of the rotating shaft  15  in the axial direction, and a flange-shaped end plate  37  extending from one end of the bearing body  36  in the radial direction of the rotating shaft  15 . The end plate  37  is overlapped on the upper surface of the first cylinder body  29   a  so as to cover the inner diameter part of the first cylinder body  29   a  from above. 
     The end plate  37  of the first bearing  19  is surrounded by a ring-shaped support frame  33 . The support frame  38  is fixed to a predetermined position on the inner surface of the peripheral wall  10   a  of the sealed container  10  by, for example, means such as welding. 
     A first cylinder body  29   a  is connected to the lower surface of the support frame  38  via a plurality of fastening bolts  39  (only one shown). 
     Furthermore, the end plate  37  of the first bearing  19 , the first cylinder body  29   a , the first partition plate  17 , and the second cylinder body  29   b  are overlaid in the axial direction of the rotating shaft  15 , and are integrally connected via a plurality of fastening bolts (not shown). 
     The second bearing  20  is arranged below the third cylinder body  29   c . The second bearing  20  includes a tubular bearing body  41  that rotatably supports the second journal portion  24   b  of the rotating shaft  15  in the axial direction, and a flange-shaped end plate  42  extending from one end of the bearing body  41  in the radial direction of the rotating shaft  15 . The end plate  42  is overlaid on the lower surface of the third cylinder body  29   c  so as to cover the inner diameter part of the third cylinder body  29   c  from below. 
     The end plate  42  of the second bearing  20 , the third cylinder body  29   c , the second partition plate  18 , and the second cylinder body  29   b  are overlaid in the axial direction of the sealed container  10  and integrally connected via a plurality of fastening bolts (not shown). 
     According to the present embodiment, a region surrounded by the inner diameter part of the first cylinder body  29   a , the first partition plate  17 , and the end plate  37  of the first bearing  19  defines a first cylinder chamber  43 . The first crank portion  23   a  of the rotating shaft  15  is accommodated in the first cylinder chamber  43 . 
     A region surrounded by the inner diameter part of the second cylinder body  29   b , the first partition plate  17 , and the second partition plate  18  defines a second cylinder chamber  44 . The second crank portion  23   b  of the rotating shaft  15  is accommodated in the second cylinder chamber  44 . 
     Furthermore, a region surrounded by the inner diameter part of the third cylinder body  29   c , the second partition plate  18 , and the end plate  42  of the second bearing  20  defines a third cylinder chamber  45 . The third crank portion  23   c  of the rotating shaft  15  is accommodated in the third cylinder chamber  45 . 
     As shown in  FIGS. 2 and 3 , a first muffler cover  46  is attached to the first bearing  19 . The first muffler cover  46  and the first bearing  19  cooperate with each other to define a first muffler chamber  47 . The first muffler chamber  47  is attached around the first bearing  19  so as to surround the bearing body  36  of the first bearing  19  and is spaced from the first cylinder chamber  47  by the end plate  37  of the first bearing  19 . 
     Furthermore, the first muffler chamber  47  has a sufficient capacity for enhancing the muffling effect, and is opened inside the sealed container  10  through a plurality of exhaust holes (not shown) included in the first muffler cover  46 . 
     A second muffler cover  48  is attached to the second bearing  20 . The second muffler cover  48  and the second bearing  20  cooperate with each other to define a second muffler chamber  49 . The second muffler chamber  49  is attached around the second bearing  20  so as to surround the bearing body  41  of the second bearing  20 , raid is separated from the third cylinder chamber  45  by the end plate  42  of the second bearing  20 . 
     Furthermore, the second muffler chamber  49  has a sufficient capacity for enhancing the muffling effect. According to the present embodiment, the second muffler chamber  49  communicates with the first muffler chamber  47  via a discharge passage  51  extending in the axial direction of the rotating shaft  15 . The discharge passage  51  continuously penetrates outer peripheral portions of the first to third cylinder bodies  29   a ,  29   b , and  29   c , and the outer peripheral portions of the first and second partition plates  17  and  13  first and second partitions so as to connect the first muffler chamber  47  and the second muffler chamber  49 . 
     As shown in  FIGS. 2 and 3 , a ring-shaped first roller  52  is fitted in the outer peripheral surface of the first crank portion  23   a . The first roller  52  rotates eccentrically inside the first cylinder chamber  43 , integrally with the rotating shaft  15 , and a part of the outer peripheral surface of the first roller  52  cooperates with the inner peripheral surface of the inner diameter portion of the first cylinder body  29   a  to form a seal portion. 
     An upper end surface of the first roller  52  is slidably inn contact with a lower surface of the end plate  37  of the first bearing IS. The lower end surface of the first roller  52  is slidably in contact with the upper surface of the first partition plate  17  around the through hole  30 . The airtightness of the first cylinder chamber  43  is thereby secured. 
     A ring-shaped second roller  53  is fitted in the outer peripheral surface of the second crank portion  23   b . The second roller  53  rotates eccentrically inside the second cylinder chamber  44 , integrally with the rotating shaft  15 , and a part of the outer peripheral surface of the second roller  53  cooperates with an inner peripheral surface of the inner diameter part of the second cylinder body  29   b  to firm a seal portion. 
     The upper end surface of the second roller  53  is slidably in contact with the lower surface of the first partition plate  17  around the through hole  30 . The lower end surface of the second roller  53  is slidably in contact with the upper surface of the second partition plate  13  around the bearing hole  33 . The airtightness of the second cylinder chamber  44  is thereby secured. 
     A ring-shaped third roller  54  is fitted in the outer peripheral surface of the third crank portion  23   c . The third roller  54  rotates eccentrically inside the third cylinder chamber  45 , integrally with the rotating shaft  15 , and a part of the outer peripheral surface of the third roller  54  cooperates with the inner peripheral surface of the inner diameter part of the third cylinder body  29   c  to form a seal portion. 
     The upper end surface of the third roller  54  is slidably in contact with the lower surface of the second partition plate  18  around the communication hole  34 . A lower end surface of the third roller  54  is slidably in contact with an upper surface of the end plate  42  of the second bearing  20 . The airtightness of the third cylinder chamber  45  is thereby secured. 
     As the first refrigerant compression unit  16 A is shown as a representative in  FIG. 4 , a vane  56  is slidably provided on the first cylinder body  29   a . The vane  56  can move in the direction of advancing to the first cylinder chamber  43  or retreating from the first cylinder chamber  43 , and a distal end of the vane  56  is slidably pressed against the outer peripheral surface of the first roller  52 . 
     The vane  56  cooperates with the first roller  52  to partition the first cylinder chamber  43  into a suction region R 1  and a compression region R 2 . For this reason, when the first roller  52  rotates eccentrically in the first cylinder chamber  43 , the volumes of the suction region R 1  and the compression region R 2  of the first cylinder chamber  43  change continuously. Although not shown, each of the second cylinder chamber  44  and the third cylinder chamber  45  is also divided into a suction region R 1  and a compression region R 2  by a similar vane. 
     As shown in  FIG. 3 , the first to third cylinder bodies  29   a ,  29   b , and  29   c  have suction ports  57  that open to the suction regions R 1  of the first to third cylinder chambers  43 ,  44 , and  45 . Furthermore, first to third connecting pipes  58   a ,  58   b , and  58   c  are connected to the suction ports  57  of the first to third cylinder bodies  29   a ,  29   b , and  29   c . The first to third connecting pipes  58   a ,  58   b , and  58   c  penetrate the peripheral wall  10   a  of the sealed container  10  and protrude to the outside of the sealed container  10 . 
     As shown in  FIG. 2 , the accumulator  8  of the rotary compressor  2  is attached to the side of the sealed container  10  in a vertically standing posture. The accumulator  8  includes three branch pipes  59   a ,  59   b , and  59   c  that distribute the vapor-phase refrigerant from which the liquid-phase refrigerant is separated to the compression mechanism unit  12 . The branch pipes  59   a ,  59   b , and  59   c  penetrate the bottom part of the accumulator  8  and are guided to the outside of the accumulator  8 , and are airtightly connected to opening ends of the first to third connecting pipes  58   a ,  58   b , and  58   c.    
     As shown in  FIG. 3 , a recess portion  61  is formed on the upper surface of the end plate  37  of the first bearing  19 . Similarly, a recess portion  62  is formed on the lower surface of the end plate  42  of the second bearing  20 . First discharge ports  63   a  and  63   b  are formed at bottoms of the recess portions  61  and  62 , respectively. The first discharge port  63   a  formed on the end plate  37  is opened into the first cylinder chamber  43  and the first muffler chamber  47 . The first discharge port  63   b  formed on the end plate  42  is opened into the third cylinder chamber  45  and the second muffler chamber  49 . 
     The first discharge ports  63   a  and  63   b  have, for example, a circular opening shape. A basic port diameter L 1  of the first discharge ports  63   a  and  63   b  is, for example, 13 [mm]. A minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b  determined by the port diameter L 1  is, for example, 132,7 [mm 2 ]. 
     In the present embodiment, the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b  is equal. However, the first discharge ports  63   a  and  63   b  may have minimum cross-sectional areas A 1  different from each other. 
     A reed valve  64  for opening and closing the first discharge port  63   a  is incorporated in the recess portion  61  of the end plate  31 . The reed valve  64  opens the first discharge port  63   a  when the pressure in the compression region R 2  of the first cylinder chamber  43  reaches a predetermined value. 
     A reed valve  66  for opening and closing the first discharge port  63   b  is incorporated in the recess portion  62  of the end plate  42 . The reed valve  66  opens the first discharge port  63   b  when the pressure in the compression region R 2  of the third cylinder chamber  45  reaches a predetermined value. 
     As shown in  FIG. 3 , the plate element  31   a  of the first partition plate  11  and the plate element  32   a  of the second partition plate  18  cooperate with each other to sandwich the intermediate second cylinder body  29   b  located between the first cylinder body  29   a  and the third cylinder body  29   c.    
     A recess portion  69  is formed on the upper surface of the plate element  31   a  of the first partition plate  17 . Similarly, a recess portion  10  is formed on the lower surface of the plate element  32   a  of the second partition plate  18 . Second discharge ports  71   a  and  71   b  are formed at bottoms of the recess portions  69  and  70 , respectively. The second discharge port  71   a  formed in the plate element  31   a  is opened in the second cylinder chamber  44 . The second discharge port  71   b  formed in the plate element  32   a  is also opened in the second cylinder chamber  44 . 
     The second discharge ports  71   a  and  71   b  have, for example, a circular opening shape. A basic port diameter L 2  of the second discharge port  11   a  is, for example, 6,5 [mm]. The minimum cross-sectional area A 2  of the second discharge port  71   a  determined by the port diameter L 2  is, for example, 33,2 [mm 2 ]. 
     In contrast, the basic port diameter L 2  of the other second discharge port  71   b  is, for example, 13 [mm]. A minimum cross-sectional area A 2  of the other second discharge port  71   b  determined by the port diameter L 2  is, for example, 132,7 [mm 2 ], in other words, the second discharge port  71   b  has a larger port diameter L 2  and a larger minimum cross-sectional area A 2  than the second discharge port  71   a.    
     Therefore, in the second cylinder chamber  44 , a pair of second discharge ports  71   a  and  71   b  having different sizes are provided on both sides along the thickness direction thereof. 
     A reed valve  72  that opens and closes the second discharge port  71   a  is incorporated in the recess portion  69  of the plate element  31   a  of the first partition plate  17 . The reed valve  72  opens the second discharge port  71   a  when the pressure in the compression region R 2  of the second cylinder chamber  44  reaches a predetermined value. 
     A reed valve  74  that opens and closes the second discharge port  71   b  is incorporated in the recess portion  70  of the plate element  32   a  of the second partition plate  13 . The reed valve  74  opens the second discharge port  71   b  when the pressure in the compression region R 2  of the second cylinder chamber  44  reaches a predetermined value. 
     Furthermore, a recess portion  77  is formed on the lower surface of the plate element  31   b  of the first partition plate  17 . Similarly, a recess portion  78  is formed on the upper surface of the plate element  32   b  of the second partition plate  18 . Third discharge ports  79   a  and  79   b  are formed at bottoms of the recesses  77  and  78 , respectively. The third discharge port  79   a  formed in the plate element  31   b  is opened in the compression region R 2  of the first cylinder chamber  43 . The third discharge port  73   b  formed in the plate element  32   b  is opened in the compression region R 2  of the third cylinder chamber  45 . 
     The third discharge ports  79   a  and  79   b  have, for example, a circular opening shape. A basic port diameter L 3  of the third discharge ports  73   a  and  79   b  is, for example, 6,5 [mm]. A minimum cross-sectional area A 3  of the third discharge port  79   a  determined by the port diameter L 3  is, for example, 33,2 [mm 2 ]. The minimum cross-sectional area A 3  of the third discharge port  79   b  is smaller than the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b.    
     Therefore, in the first cylinder chamber  43 , the first discharge port  63   a  and the third discharge port  79   a  having different sizes are provided on both sides along the thickness direction thereof. Similarly, in the third cylinder chamber  45 , the first discharge port  63   b  and the third discharge port  79   b  having different sizes are provided on both sides along the thickness direction thereof. 
     Incidentally, in the present embodiment, the minimum cross-sectional area A 3  of the third discharge ports  79   a  and  79   b  is equal. However, the third discharge ports  79   a  and  79   b  may have minimum cross-sectional areas A 3  different from each other. 
     A reed valve  81  that opens and closes the third discharge port  79   a  is incorporated in the recess portion  77  of the plate element  31   b  of the first partition plate  17 . The reed valve  81  opens the third discharge port  79   a  when the pressure in the compression region R 2  of the first cylinder chamber  43  reaches a predetermined value. 
     Similarly, a reed valve  83  that opens and closes the third discharge port  73   b  is incorporated in the recess portion  73  of the plate element  32   b  of the second partition plate  18 . The reed valve  33  opens the third discharge port  79   b  when the pressure in the compression region R 2  of the third cylinder chamber  45  reaches a predetermined value. 
     As shown in  FIG. 3 , the recess portions  69  and  77  of the first partition plate  17  cooperate with each other to define a third muffler chamber  85  as an intermediate muffler chamber inside the first partition plate  17 . The third muffler chamber  85  is made to communicate with the discharge passage  51  through a muffling inner passage  86  formed inside the first partition plate  17 . The muffling passage  86  is located around the through hole  30  of the first partition plate  17 . 
     According to the present embodiment, since the first partition plate  17  including the third muffler chamber  85  and the muffling passage  86  is located between the first cylinder body  29   a  and the second cylinder body  29   b , the thickness is restricted. For this reason, the third muffler chamber  85  including the muffling passage  86  has a smaller capacity than the first muffler chamber  47  and the second muffler chamber  49 . 
     The recess portions  70  and  78  of the second partition plate  18  cooperate with each other to define a fourth muffler chamber  87  as an intermediate muffler chamber inside the second partition plate  18 . The fourth muffler chamber  87  is made to communicate with the discharge passage  51  through a muffling passage  38  formed inside the second partition plate  18 . The muffling passage  38  is located around the bearing hole  33  of the second partition plate  16 . 
     According to the present embodiment, the second partition plate  13  that rotatably supports the third journal portion  27  of the rotating shaft  15  is formed to be thicker than the first partition plate  17  having no bearing function. For this reason, the depth of the recess portion  70  can be sufficiently secured by making the plate element  32   a  having the bearing hole  33  thicker than the other plate elements  31   a ,  31   b , and  32   b.    
     Therefore, in the present embodiment, the capacity of the fourth muffler chamber  87  including the muffling passage  88  is smaller than the capacities of the first muffler chamber  47  and the second muffler chamber  49 , but larger than the capacity of the third muffler chamber  85  including the third muffler chamber  86 . 
     In such a three-cylinder rotary compressor  2 , when the rotating shaft  15  is driven by the electric motor  11 , the first to third rollers  52 ,  53 , and  54  eccentrically rotate in the first to third cylinder chambers  43 ,  44 , and  45 . As a result, the volumes of the suction region R 1  and the compression region R 2  of the first to third cylinder chambers  43 ,  44 , and  45  change, and the vapor-phase refrigerant in the accumulator  8  is sucked into the suction regions R 1  of the first to third cylinder chambers  43 ,  44 , and  45  through the three branch pipes  59   a ,  59   b , and  59   c.    
     The vapor-phase refrigerant sucked into the suction region R 1  of the first cylinder chamber  43  is gradually compressed in the process in which the suction region R 1  shifts to the compression region R 2 . When the pressure of the compressed vapor-phase refrigerant reaches a predetermined value, the reed valves  64  and  81  are opened and the first discharge port  63   a  and the third discharge port  79   a  are opened. 
     For this reason, the vapor-phase refrigerant compressed in the first cylinder chamber  43  is discharged from the first discharge port  63   a  to the first muffler chamber  47 , and also discharged from the third discharge port  79   a  to the third muffler chamber  85 . The vapor-phase refrigerant discharged to the third muffler chamber  85  is guided to the first muffler chamber  47  through the muffling passage  86  and the discharge passage  51  to merge with the vapor-phase refrigerant discharged from the first discharge port  63   a  in the first muffler chamber  47 . 
     The vapor-phase refrigerant sucked into the suction region R 1  of the second cylinder chamber  44  is gradually compressed in the process in which the suction region R 1  shifts to the compression region R 2 . When the pressure of the compressed vapor-phase refrigerant reaches a predetermined value, the reed valves  72  and  74  are opened and the second discharge ports  71   a  and  71   b  are opened. 
     For this reason, the vapor-phase refrigerant compressed in the second cylinder chamber  44  is discharged to the third muffler chamber  35  through the second discharge port  71   a  and also discharged to the fourth muffler chamber  87  through the second discharge port  71   b . The vapor-phase refrigerant discharged into the third muffler chamber  85  is guided to the first muffler chamber  47  through the muffling passage  86  and the discharge passage  51 . The vapor-phase refrigerant discharged into the fourth muffler chamber  87  is guided to the first muffler chamber  47  through the muffling passage  88  and the discharge passage  51 . 
     The vapor-phase refrigerant sucked into the suction region R 1  of the third cylinder chamber  45  is gradually compressed in the process in which the suction region R 1  shifts to the compression region R 2 . When the pressure of the compressed vapor-phase refrigerant reaches a predetermined value, the reed valves  66  and  83  are opened and the first discharge port  63   b  and the third discharge port  79   b  are opened. For this reason, the vapor-phase refrigerant compressed in the third cylinder chamber  45  is discharged from the first discharge port  63   b  to the second muffler chamber  49  and also discharged from the third discharge port  79   b  to the fourth muffler chamber  87 . The vapor-phase refrigerant discharged into the second muffler chamber  49  is guided to the first muffler chamber  47  through the discharge passage  51 . The vapor-phase refrigerant discharged into the fourth muffler chamber  37  is guided to the first muffler chamber  47  through the muffling passage  83  and the discharge passage  51 . 
     According to the present embodiment, a part of the vapor-phase refrigerant compressed in the first cylinder chamber  43  and a part of the vapor-phase refrigerant compressed in the second cylinder chamber  44  are discharged from the third discharge port  79   a  and the second discharge port  71   a  to the common third muffler chamber  85 . 
     Similarly, a part of the vapor-phase refrigerant compressed in the third cylinder chamber  45  and the rest of the vapor-phase refrigerant compressed in the second cylinder chamber  44  are discharged from the third discharge port  79   b  and the second discharge port  71   b  to the common fourth muffler chamber  87 . 
     In other words, the vapor-phase refrigerant compressed in the first to third cylinder chambers  43 ,  44 , and  45  is discharged from both sides along the thickness direction, of the first to third cylinder chambers  43 ,  44 , and  45 , respectively. 
     At this time, since the eccentric directions of the first to third crank portions  23   a ,  23   b , and  23   c  of the rotating shaft  15  are deviated by 120° in the circumferential direction of the rotating shaft  15 , an equivalent phase difference is made at the timing at which the vapor-phase refrigerant compressed in the first to third cylinder chambers  43 ,  44 , and  45  is discharged. 
     For this reason, the vapor-phase refrigerant discharged from the first cylinder chamber  43  to the third muffler chamber  85  and the vapor-phase refrigerant discharged from the second cylinder chamber  44  to the third muffler chamber  65  do not interfere with each other in the third muffler chamber  85 . Similarly, the vapor-phase refrigerant discharged from the third cylinder chamber  45  to the fourth muffler chamber  67  and the vapor-phase refrigerant discharged from the second cylinder chamber  44  to the fourth muffler chamber  87  are the fourth. They do not interfere with each other in the muffler chamber  87 . 
     Therefore, the vapor-phase refrigerant discharged into the third, muffler chamber  65  and the fourth muffler chamber  37  is guided to the first muffler chamber  47  through the discharge passage  51  without causing a large loss. 
     The vapor-phase refrigerant discharged to the second to fourth muffler chambers  49 ,  85 , and  87  merges with the vapor-phase refrigerant discharged from the first discharge port  63   a  in the first muffler chamber  47 , and then continuously discharged from an exhaust hole of the first muffler cover  46  into the sealed container  10 . The vapor-phase refrigerant discharged into the sealed container  10  passes through the electric motor  11  and is guided from the discharge pipe  10   b  to the four-way valve  3 . 
     According to the first embodiment, the first partition plate  17  and the second partition plate  13  sandwiching the intermediate second cylinder chamber  44  located between the first cylinder chamber  43  and the third cylinder chamber  45  comprise the second discharge ports  71   a  and  71   b  that open into the second cylinder chamber  44 , and the third muffler chamber  85  and the fourth muffler chamber  87  that are connected to the second discharge ports  71   a  and  71   b , respectively. 
     For this reason, the vapor-phase refrigerant compressed in the second cylinder chamber  44  is discharged from both sides along the thickness direction of the second cylinder chamber  44  to the third, muffler chamber  85  and the fourth muffler chamber  87  through the pair of discharge ports  71   a  and  71   b . Therefore, although the thicknesses of the first partition plate  17  and the second partition plate  13  that sandwich the second cylinder chamber  44  are limited, the flow rate of the vapor-phase refrigerant discharged from the second cylinder chamber  44  can be increased and the discharge loss and discharge pressure pulsation of the vapor-phase refrigerant can be reduced. 
     Moreover, in the first embodiment, the first discharge port  63   a  formed on the first bearing  19  and the third discharge port  79   a  formed on the first chamber  43 . For this reason, the vapor-phase refrigerant compressed in the first cylinder chamber  43  is discharged from the first discharge port  63   a  and the third discharge port  79   a  to both the first muffler chamber  47  and the third muffler chamber  85 . 
     In addition, since the first discharge port  63   b  formed on the second bearing  20  and the third discharge port  79   b  formed on the second partition plate  18  are opened in the third cylinder chamber  45 , the vapor-phase refrigerant compressed in the cylinder chamber  45  is discharged from the first discharge port  63   b  and the third discharge port  79   b  to both the second muffler chamber  49  and the fourth muffler chamber  37 . 
     As a result, ail the vapor-phase refrigerant compressed in the first to third cylinder chambers  43 ,  44 , and  45  is discharged from the two discharge ports, and the passage resistance and the discharge pressure pulsation are suppressed to a low level when the vapor-phase refrigerant passes through each of the discharge ports. Therefore, the vapor-phase refrigerant compressed in the first to third cylinder chambers  43 ,  44 , and  45  can be discharged more efficiently, and a high-performance rotary compressor  2  can be obtained. 
     At the same time, each of the region from the third muffler chamber  85  to the muffling passage  66  of fourth muffler chamber  67  to the muffling passage  88  of the second partition plate  18  can be used as space for muffling. For this reason, the noise generated when the compressed, vapor-phase refrigerant flows can be reduced, and quiet operation can be performed. 
     As shown in  FIG. 3 , the first discharge port  63   a  and the third discharge port  79   a  that open into the first cylinder chamber  43  have different sizes. Similarly, the second discharge ports  71   a  and  71   b  that open into the second cylinder chamber  44  have different sizes, and the first discharge port  63   b  and the third discharge port  79   b  that open into the third cylinder chamber  45  are also different in size from each other. 
     Therefore, the discharge flow rate of the vapor-phase refrigerant discharged on both sides along the thickness direction of the first to third cylinder chambers  43 ,  44 , and  45  can be made different from each other, in each of the first to third cylinder chambers  43 ,  44 , and  45 . 
     More specifically, in the first embodiment, the first muffler chamber  47  attached to the first bearing  19  and the second muffler chamber  49  attached to the second bearing  20  have a larger capacity than that of the third muffler chamber  85  inside the first partition plate  17  and the fourth muffler chamber  87  inside the second partition plate  18 . 
     Therefore, by designing the first discharge ports  63   a  and  63   b  that open to the first muffler chamber  47  and the second muffler chamber  49  to be larger than the third discharge ports  79   a  and  79  that open to the third muffler chamber  85  and the fourth muffler chamber  37 , the flow rate of the vapor-phase refrigerant discharged from the first discharge ports  63   a  and  63   b  and the third discharge ports  79   a  and  79   b  can be optimized so as to correspond to the capacities of the first to fourth muffler chambers  47 ,  49 ,  85 , and  37 . 
     Furthermore, when the first discharge ports  63   a  and  63   b  nave a size corresponding to the capacities of the first muffler chamber  47  and the second muffler chamber  49 , the flow rate of the vapor-phase refrigerant discharged from the first cylinder chamber  43  and the third cylinder chamber  45  can be secured even if the third discharge ports  79   a  and  79   b  that open in the third muffler chamber  85  and the fourth muffler chamber  87  having a small capacity than the first muffler chamber  47  and the second muffler chamber  49  are downsized. 
     Therefore, the vapor-phase refrigerant compressed in the first and third cylinder chambers  43  and  45  can be discharged efficiently, which is more convenient for improving the performance of the rotary compressor  2 . 
     In addition, since the second partition plate  13  having a bearing function is formed to be thicker than the first partition plate  17  through which the rotating shaft  15  only penetrates, the capacity of the fourth muffler chamber  87  can be increased as compared with the capacity of the third muffler chamber  85 . 
     In particular, in the present embodiment, the total value of the minimum cross-sectional area A 2  of the second discharge port  71   a  and the minimum cross-sectional area A 3  of the third discharge port  79   a , which are formed on the first partition plate  17 , is 66,4 [mm 2 ]. In contrast, the total value of the minimum cross-sectional area A 2  of the second discharge port  71   b  and the minimum cross-sectional area A 3  of the third discharge pert  79   b , which are formed on the second partition plate  18 , is 165,9 [mm 2 ], As a result, the flow rate of the vapor-phase refrigerant discharged to the fourth muffler chamber  87  having a large capacity can be increased, and the inside of the second partition plate  18  can be effectively utilized as a flow path for the vapor-phase refrigerant. 
     As shown in  FIG. 3 , the second partition plate  18  is located on a side closer to the second muffler chamber  49  than the first partition plate  17 , and the first partition plate  17  is located on a side closer to the first muffler chamber  47  than the second partition plate  18 . In other words, the fourth muffler chamber  87  inside the second partition plate  18  is located on a side farther from the first muffler chamber  47  than the third muffler chamber  85  inside the first partition plate  17 . 
     As a result, the flow path of the refrigerant from the fourth muffler chamber  87  to the first muffler chamber  47  becomes much longer than the flow path of the refrigerant from the third muffler chamber  85  to the first muffler chamber  47 . In other words, the capacity of the flow path of the refrigerant increases, but the flow path resistance applied to the vapor-phase refrigerant increases as the flow path becomes longer. As a result, the discharge pressure pulsation of the vapor-phase refrigerant flowing from the fourth muffler chamber  81  to the first muffler chamber  47  is suppressed and the muffling effect can be enhanced. 
     Furthermore, in the first embodiment, as described above, the total value of the minimum cross-sectional area A 2  of the second discharge port  71   b  and the minimum cross-sectional area A 3  of the third discharge port  79   b , which are formed on the second partition plate  18 , is larger than the total value of the minimum cross-sectional area A 2  of the second discharge port  71   a  and the minimum cross-sectional area A 3  of the third discharge port  79   a , which are formed on the first partition plate  17 . 
     Thus, the flow rate of the vapor-phase refrigerant discharged to the fourth muffler chamber  87  located on the side far from the first muffler chamber  47  can be increased, and a high-performance rotary compressor  2  can be obtained while increasing the capacity of the flow path and suppressing the noise during the operation. 
     Second Embodiment 
       FIG. 5  discloses a second embodiment. The second embodiment is different from the first embodiment with respect to elements related to the size of the first to third discharge ports  63   a ,  63   b ,  71   a ,  71   b ,  79   a , and  79   b  opened in the first to third cylinder chambers  43 ,  44 , and  45 , and is the same as the first embodiment with respect to the configuration of the rotary compressor  2  other than the above. For this reason, in the second embodiment, the same reference numerals are denoted to the same constituent portions as those in the first embodiment, and their descriptions will be omitted. 
     In the second embodiment, as shown in  FIG. 5 , the basic port diameter L 2  and the minimum cross-sectional area A 2  of the second discharge port  71   a  formed on the first partition plate  17  are set to be equivalent to, for example, the basic port diameter L 1  and the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b.    
     Furthermore, the basic port diameter L 2  and the minimum cross-sectional area A 2  of the second discharge port  71   b  formed on the second partition plate  18  are set to be equivalent to, for example, the basic port diameter L 3  and the minimum cross-sectional area A 3  of the third discharge ports  79   a  and  79   b.    
     For this reason, the total value of the minimum cross-sectional region A 2  of the second discharge port  71   a  and the minimum cross-sectional region A 3  of the third discharge port  79   a , which are formed on the first partition plate  17 , is 66,4 [mm 2 ]. In contrast, the total value of the minimum cross-sectional region A 2  of the second discharge port  71   b  and the minimum cross-sectional region A 3  of the third discharge port  79   b , which are formed on the second partition plate  18 , is 165,9 [mm 2 ]. 
     As a result, the flow rate of the vapor-phase refrigerant discharged to the third muffler chamber  85  located on the side near the first muffler chamber  47  where the vapor-phase refrigerant discharged from the first to third cylinder chambers  43 ,  44 , and  45  merges can be increased. 
     Furthermore, since the third muffler chamber  85  is adjacent to the first muffler chamber  47  with the first cylinder body  29   a  provided therebetween, the flow path of the refrigerant from the third muffler chamber  85  to the first muffler chamber  47  is significantly shorter than the flow path of the refrigerant from the fourth muffler chamber  87  to the first muffler chamber  47 . 
     As a result, the high-performance rotary compressor  2  capable of suppressing the flow path loss of the vapor-phase refrigerant from the third muffler chamber  85  to the first muffler chamber  47  and increasing the flow rate of the vapor phase refrigerant can be obtained. 
     Third Embodiment 
       FIG. 6  discloses a third embodiment. The third embodiment is different from the first embodiment with respect to elements related to the size of the first to third discharge ports  63   a ,  63   b ,  71   a ,  71   b ,  79   a , and  79   b  opened in the first to third cylinder chambers  43 ,  44 , and  45 , and is the same as the first embodiment with respect to the configuration of the rotary compressor  2  other than the above. For this reason, in the third embodiment, the same reference numerals are denoted to the same constituent portions as those in the first embodiment, and their descriptions will be omitted. 
     In the third embodiment, as shown in  FIG. 6 , the basic port diameter L 2  and the minimum cross-sectional area A 2  of the second discharge port  71   a  formed on the first partition plate  17  are set to be intermediate values between the basic port diameter L 1  and the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b , and the port diameter L 3  and the minimum cross-sectional area A 3  of the third discharge ports  79   a  and  79   b , respectively. 
     Similarly, the basic port diameter L 2  and the minimum cross-sectional area A 2  of the second discharge port lib formed on the second partition plate  18  are set to be intermediate values between the basic port diameter L 1  and the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b , and the basic port diameter L 3  and the minimum cross-sectional area A 3  of the third discharge ports  79   a  and  79   b , respectively. 
     More specifically, the minimum cross-sectional area A 2  of the second discharge ports  71   a  and  71   b  is, for example, 60,3 [mud]. Therefore, the minimum cross-sectional area A 1  of the first discharge ports  63   a  and  63   b , the minimum cross-sectional area A 2  of the second discharge ports  71   a  and  71   b , and the minimum cross-sectional area A 3  of the third discharge ports  79   a  and  79   b  meet a relationship A 1 &gt;A 2 &gt;A 3 . 
     As a result, the second discharge ports  71   a  and  71   b  that open in the second cylinder chamber  44  between the first cylinder chamber  43  and the third cylinder chamber  45  have an opening shape smaller than the first discharge ports  63   a  and  63   b  and larger than the third discharge ports  79   a  and  79   b.    
     According to the third embodiment, the first partition plate  17  and the second partition plate  18  sandwiching the second cylinder chamber  44  include the smallest third discharge ports  79   a  and  79   b  and the second discharge ports  71   a  and  71   b  having an intermediate size. The second discharge ports  71   a  and  71   b  having an intermediate size are opened in the second cylinder chamber  44 , and the smallest third discharge ports  79   a  and  79   b  are opened to both the first cylinder chamber  43  and the third cylinder chamber  45 . 
     According to this configuration, the largest first discharge ports  63   a  and  63   b  and the smallest third discharge ports  79   a  and  79   b  open in the first cylinder chamber  43  and the third cylinder chamber  45 , respectively, and the second discharge ports  71   a  and  71   b  having an intermediate size open in the second cylinder chamber  44 . 
     Therefore, the flow rate of the vapor-phase refrigerant discharged from the first discharge ports  63   a  and  63   b , the second discharge ports  71   a  and  71   b , and the third discharge ports  79   a  and  79   b  can be optimized to correspond to the capacities of the first to fourth muffler chambers  47 ,  49 ,  85 , and  87 . Therefore, the vapor-phase refrigerant compressed in the first to third cylinder chambers  43 ,  44 , and  45  can be discharged more efficiently, and the performance of the rotary compressor  2  can be enhanced. 
     In addition, since the second partition plate  18  having a bearing function is formed to be thicker than the first first partition plate  17  through which the rotating shaft  15  only penetrates, the capacity of the fourth muffler chamber  87  can be made larger than the capacity of the third muffler chamber  85 . For this reason, there is an advantage that the flow rate of the vapor-phase refrigerant discharged to the fourth muffler chamber  87  having a large capacity can be increased by making the second discharge port  71   b  opened in the fourth muffler chamber  87  larger than the third discharge port  79   b , which effectively contributes to improvement of the performance of the rotary compressor  2 . 
     In the above embodiments, the opening shape of the discharge port is a circular shape. However, the opening shape of the discharge port is not particularly limited, but may be, for example, a polygonal shape or a D shape in which an are and a straight line are combined. 
     In the above embodiments, the three-cylinder rotary compressor including three cylinder chambers has been described. However, the embodiments can also be applied to, for example, a rotary compressor having four or more cylinder chambers, similarly. 
     Furthermore, in the above embodiments, an example of a general rotary compressor in which the vane advances in the cylinder chamber following the eccentric rotation of the roller or moves in the direction of retreating from the cylinder chamber has been described. However, the embodiments can also be applied to, for example, a so-called swing-type rotary compressor in which vanes are made to integrally project from the outer peripheral surface of the roller toward the radial outer side of the roller. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions,