Abstract:
A rotary compressor, used e.g. in an air conditioner, includes a compressing unit having an end plate that closes an end portion of an annular cylinder. The end plate includes a groove portion accommodating a discharge valve portion having a reed valve type discharge valve and a discharge-valve limiter. The discharge valve portion is attached to the groove portion with a rivet. The groove portion has a rivet-side enlarged diameter portion formed into a semicircular step shape, and a diameter of the rivet-side enlarged diameter portion other than a bottom side thereof is larger than a diameter of the bottom side. This prevents a punch P that swages the rivet from interfering with the groove portion when attaching the discharge valve portion to the groove portion with the rivet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-218484, filed on Sep. 28, 2012, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a rotary compressor used, for example, in an air conditioner. 
     2. Description of the Related Art 
     In a conventional rotary compressor, first and second groove portions  563 S and  563 T (see  FIG. 7 ) are formed in a lower end plate  160 S and an upper end plate  160 T of a compressing unit  12  (see  FIG. 1 ), respectively. The first and second groove portions  563 S and  563 T accommodate reed valve type first and second discharge valves  200 S and  200 T, which open and close first and second discharge openings  190 S and  190 T, and first and second discharge-valve limiters  201 S and  201 T, which are used to limit valve-opening amount of the first and second discharge valves  200 S and  200 T when they are deflected (hereinafter, deflection opening amount of the first and second discharge valves  200 S and  200 T), respectively. Furthermore, the first and second groove portions  563 S and  563 T are formed such that the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  201 T are attached with first and second rivets  203 S and  203 T, respectively (see  FIGS. 7 and 8 ). 
     On the side the first and second discharge openings  190 S and  190 T of the first and second groove portions  563 S and  563 T, the diameter (width) of the first and second groove portions  563 S and  563 T is enlarged so as to form first and second discharge-opening-side enlarged diameter portions  563 Sb and  563 Tb, respectively. Also on the side of the first and second rivets  203 S and  203 T, the diameter (width) of the first and second groove portions  563 S and  563 T is enlarged so as to form first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta, respectively. 
     As illustrated in  FIG. 8 , the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  201 T are attached to the inside of the first and second groove portions  563 S and  563 T (the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta) with the first and second rivets  203 S and  203 T inserted into first and second rivet holes  191 S and  191 T, respectively. The first and second rivet holes  191 S and  191 T are provided in the bottom portions of the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta, respectively. 
     The first and second discharge-opening-side enlarged diameter portions  563 Sb and  563 Tb are formed by enlarging the diameter (width) of the first and second groove portions  563 S and  563 T, respectively. That is, the first and second discharge-opening-side enlarged diameter portions  563 Sb and  563 Tb have a diameter (width) which is larger than that of the first and second groove portions  563 S and  563 T, respectively. Consequently, a path of compressed refrigerant gas is formed through which the compressed refrigerant gas discharged from the first and second discharge openings  190 S and  190 T ejects pushing open the first and second discharge valves  200 S and  200 T, respectively. 
     At the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta, the first and second groove portions  563 S and  563 T are enlarged to have a diameter (width) Ha which is larger than that of the first and second groove portions  563 S and  563 T. This prevents a punch P of a swaging machine (not shown) from interfering with an inner wall portions of the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta, when swaging, i.e. pressing or applying pressure by the punch P to cause plastic deformation, first and second swaging portions  203 Sa and  203 Ta of the first and second rivets  203 S and  203 T. As illustrated in  FIG. 9 , when the first and second swaging portions  203 Sa and  203 Ta are swaged, the swaging machine presses a tip N of the punch P against the first and second swaging portions  203 Sa and  203 Ta and make the punch P perform a rosette-like axial motion (motion of moving on a conical petal-like trajectory Y) about the central axis Z of the first and second rivets  203 S and  203 T in order to swage the first and second swaging portions  203 Sa and  203 Ta. 
     The thickness t s  of the bottom portions of the first and second groove portions  563 S and  563 T (including the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta and the first and second discharge-opening-side enlarged diameter portions  563 Sb and  563 Tb) is made as thin as possible so as to prevent backflow of the compressed refrigerant gas trapped in the first and second discharge openings  190 S and  190 T toward first and second operating chambers  130 S and  130 T (see  FIG. 2 ) and prevent the volumetric efficiency of refrigerant compression from decreasing. 
     In a conventional hermetic type compressor (rotary compressor) including a cylinder chamber formed from a cylinder and a bearing, wherein refrigerant gas drawn into the cylinder chamber is compressed, and the refrigerant gas is discharged by opening a discharge valve provided in the bearing, it is known to a skilled person in the art that a hermetic type compressor (rotary compressor) includes a recessed portion (groove portion) formed in the bearing, a valve limiter press-fitted into the recessed portion (groove portion), and the discharge valve inserted between the valve limiter and the bearing recessed portion (groove portion) such that it is openable and closable. The valve limiter and the discharge valve each include a mounting hole, and a mounting bolt for mounting the bearing on the cylinder is inserted into the mounting holes so that the valve limiter and the discharge valve are fixedly mounted on the cylinder together with the bearing (for example, see Japanese Laid-open Patent Publication No. 08-200264). 
     However, according to the conventional technology described with reference to  FIG. 7  to  FIG. 9 , as illustrated in  FIG. 8 , each of the bottom portions of the first and second rivet-side enlarged diameter portions  563 Sa and  563 Ta has a small thickness ts in entire area of the bottom portions. That is, the area having the small thickness ts is larger than the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  201 T are attached to the bottom portions with the first and second rivets  203 S and  203 T, respectively. Therefore, when each of the first and second swaging portions  203 Sa and  203 Ta of the first and second rivets  203 S and  203 T is swaged by using the punch P, the bottom portion is deflected due to the swage load and the flatness deteriorates. Thus, the adhesiveness and the airtightness between the lower and upper end plates  160 S and  160 T and first and second cylinders  121 S and  121 T decrease. 
     The present invention is achieved in view of the above and has an object to obtain a rotary compressor that is capable of performing a rosette-like axial motion of a punch by a swage and includes lower and upper end plates in which bottom portions of first and second rivet-side enlarged diameter portions are not deflected. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to an aspect of the present invention, a rotary compressor includes a hermetic vertical compressor housing that includes a discharge unit that discharges refrigerant provided in an upper portion of the housing, and a suction unit for the refrigerant is provided in a lower portion of side surface of the housing; 
     a compressing unit that is arranged in a lower portion of the compressor housing and includes an annular cylinder, an end plate that includes a bearing portion and a discharge valve portion and closes an end portion of the cylinder, an annular piston that is fitted to an eccentric portion of a rotating shaft supported by the bearing portion, revolves in the cylinder along a cylinder inner-wall of the cylinder, and forms an operating chamber between the annular piston and the cylinder inner-wall, and a vane that comes into contact with the annular piston by projecting into the operating chamber from an inside of a vane groove of the cylinder and divides the operating chamber into a suction chamber and a compression chamber, and that draws a refrigerant through the suction unit and discharges a refrigerant from the discharge unit through an inside of the compressor housing; and a motor that is arranged in an upper portion of the compressor housing and drives the compressing unit via the rotating shaft. 
     The end plate has a groove portion accommodating the discharge valve portion that includes a reed valve type discharge valve and a discharge-valve limiter that are attached to the groove portion with a rivet, and the groove portion has a rivet-side enlarged diameter portion which is formed into a semicircular step shape, and a diameter of the rivet-side enlarged diameter portion other than a bottom side thereof is larger than a diameter of the bottom side. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical or longitudinal cross-sectional view illustrating an embodiment of a rotary compressor according to the present invention; 
         FIG. 2  is a horizontal or transverse cross-sectional view of first and second compressing units according to the embodiment as viewed from above; 
         FIG. 3  is a partial plan view of upper and lower end plates to which first and second discharge valves and first and second discharge-valve limiters according to the embodiment are attached, respectively; 
         FIG. 4  is a partial cross-sectional view taken along line A-A in  FIG. 3 ; 
         FIG. 5  is a partial cross-sectional view taken along line B-B in  FIG. 3 ; 
         FIG. 6  is a diagram that is similar to  FIG. 5  and illustrates a state where the first and second discharge-valve limiters are deflected by swaging; 
         FIG. 7  is a partial plan view of conventional upper and lower end plates to which first and second discharge valves and first and second discharge-valve limiters are attached, respectively; 
         FIG. 8  is a partial cross-sectional view taken along line C-C in  FIG. 7 ; and 
         FIG. 9  is a perspective view illustrating a rosette-like axial motion of a punch by a swaging machine. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, an embodiment of a rotary compressor according to the present invention will be described in detail with reference to the drawings. This invention is not limited to the embodiment. 
     Embodiment 
       FIG. 1  is a vertical or longitudinal cross-sectional view illustrating the embodiment of a rotary compressor according to the present invention, and  FIG. 2  is a horizontal or transverse cross-sectional view of first and second compressing units according to the embodiment as viewed from above. 
     As illustrated in  FIG. 1 , a rotary compressor  1  in the embodiment includes a compressing unit  12 , which is arranged in the lower portion of a hermetic vertical cylindrical compressor housing  10 , and a motor  11 , which is arranged in the upper portion of the compressor housing  10  and drives the compressing unit  12  via a rotating shaft  15 . 
     A stator  111  of the motor  11  is cylindrically shaped and is shrink-fitted and fixed to the inner periphery of the compressor housing  10 . A rotor  112  of the motor  11  is arranged in the cylindrical stator  111  and is shrink-fitted and fixed to the rotating shaft  15  connecting the motor  11  and the compressing unit  12  mechanically. 
     The compressing unit  12  includes a first compressing unit  12 S and a second compressing unit  12 T that is arranged parallel to the first compressing unit  12 S and is stacked on the upper side of the first compressing unit  12 S. As illustrated in  FIG. 2 , the first and second compressing units  12 S and  12 T include annular first and second cylinders  121 S and  121 T, respectively. The first and second cylinders  121 S and  121 T have first and second side protrusions, respectively. First and second suction openings  135 S and  135 T and first and second vane grooves  128 S and  128 T are radially provided in the first and second side protrusions, respectively. 
     As illustrated in  FIG. 2 , circular first and second cylinder inner-walls  123 S and  123 T are formed in the first and second cylinders  121 S and  121 T, respectively, concentrically with the rotating shaft  15  of the motor  11 . First and second annular pistons  125 S and  125 T, which have an outer diameter smaller than the inner diameter of the cylinder, are arranged on the inner side of the first and second cylinder inner-walls  123 S and  123 T, respectively. First and second operating chambers  130 S and  130 T, which draw refrigerant gas and discharge the refrigerant gas after compression, are formed between the first and second cylinder inner-walls  123 S and  123 T and the first and second annular pistons  125 S and  125 T, respectively. 
     In the first and second cylinders  121 S and  121 T, the first and second vane grooves  128 S and  128 T, which extend over the entire height of the cylinder, are formed radially from the first and second cylinder inner-walls  123 S and  123 T, respectively. Plate-shaped first and second vanes  127 S and  127 T are slidably fitted in the first and second vane grooves  128 S and  128 T, respectively. 
     As illustrated in  FIG. 2 , first and second spring holes  124 S and  124 T are formed in inner portions of the first and second vane grooves  128 S and  128 T, respectively, such that they communicate with the first and second vane grooves  128 S and  128 T from the outer peripheral portions of the first and second cylinders  121 S and  121 T, respectively. Vane springs (not shown) that press back surfaces of the first and second vanes  127 S and  127 T are inserted into the first and second spring holes  124 S and  124 T, respectively. When the rotary compressor  1  is started, the first and second vanes  127 S and  127 T project into the first and second operating chambers  130 S and  130 T from the inside of the first and second vane grooves  128 S and  128 T due to the repulsive force of the vane springs, respectively, and the projecting ends of the first and second vanes  127 S and  127 T come into contact with the outer peripheries of the first and second annular pistons  125 S and  125 T, respectively, whereby the first and second operating chambers  130 S and  130 T are divided into first and second suction chambers  131 S and  131 T and first and second compression chambers  133 S and  133 T by the first and second vanes  127 S and  127 T, respectively. 
     In the first and second cylinders  121 S and  1211 , first and second pressure introducing paths  129 S and  129 T are formed, respectively. The first and second pressure introducing paths  129 S and  129 T communicate the inner portions of the first and second vane grooves  128 S and  128 T with the inside of the compressor housing  10  through openings R illustrated in  FIG. 1  to introduce refrigerant gas compressed in the compressor housing  10  and apply a back pressure to the first and second vanes  127 S and  127 T due to the pressure of the refrigerant gas, respectively. 
     In the first and second cylinders  121 S and  121 T, the first and second suction openings  135 S and  135 T are formed, respectively. The first and second suction openings  135 S and  135 T cause the first and second suction chambers  131 S and  131 T and the outside to communicate with each other so as to draw refrigerant into the first and second suction chambers  131 S and  131 T from the outside, respectively. 
     Moreover, as illustrated in  FIG. 1 , an intermediate partition plate  140  is arranged between the first cylinder  121 S and the second cylinder  121 T so as to separate and close the first operating chamber  130 S of the first cylinder  121 S and the second operating chamber  130 T of the second cylinder  121 T. A lower end plate  160 S is arranged in the lower end portion of the first cylinder  121 S so as to close the first operating chamber  130 S of the first cylinder  121 S. An upper end plate  160 T is arranged in the upper end portion of the second cylinder  121 T so as to close the second operating chamber  130 T of the second cylinder  121 T. 
     A sub bearing portion  161 S is formed in the lower end plate  160 S and a sub shaft portion  151  of the rotating shaft  15  is rotatably supported by the sub bearing portion  161 S. A main bearing portion  161 T is formed in the upper end plate  160 T and a main shaft portion  153  of the rotating shaft  15  is rotatably supported by the main bearing portion  161 T. 
     The rotating shaft  15  includes a first eccentric portion  152 S and a second eccentric portion  152 T whose phases are shifted by 180° from each other. The first eccentric portion  152 S is rotatably fitted to the first annular piston  125 S of the first compressing unit  12 S and the second eccentric portion  152 T is rotatably fitted to the second annular piston  125 T of the second compressing unit  12 T. 
     When the rotating shaft  15  rotates, the first and second annular pistons  125 S and  125 T revolve counterclockwise in  FIG. 2  in the first and second cylinders  121 S and  121 T along the first and second cylinder inner-walls  123 S and  123 T, respectively. In accordance with the revolutions, the first and second vanes  127 S and  127 T reciprocate. The volume of the first and second suction chambers  131 S and  131 T and the first and second compression chambers  133 S and  133 T changes continuously due to the motion of the first and second annular pistons  125 S and  125 T and the first and second vanes  127 S and  127 T, whereby the compressing unit  12  continuously draws, compresses, and then discharges the refrigerant gas. 
     As illustrated in  FIG. 1 , a lower muffler cover  170 S is arranged on the lower side of the lower end plate  160 S such that a lower muffler chamber  180 S is formed between the lower muffler cover  170 S and the lower end plate  160 S. The first compressing unit  12 S is open to the lower muffler chamber  180 S. In other words, a first discharge opening  190 S (see  FIG. 2 ), which causes the first compression chamber  133 S of the first cylinder  121 S and the lower muffler chamber  180 S to communicate with each other, is provided near the first vane  127 S of the lower end plate  160 S. A reed valve type first discharge valve  200 S, which prevents backflow of the compressed refrigerant gas, is arranged at the first discharge opening  190 S. 
     The lower muffler chamber  180 S is an annular chamber and is part of the communication path that causes the discharge side of the first compressing unit  12 S to communicate with the inside of an upper muffler chamber  180 T through a refrigerant path  136  (see  FIG. 2 ) that passes through the lower end plate  160 S, the first cylinder  121 S, the intermediate partition plate  140 , the second cylinder  121 T, and the upper end plate  160 T. The lower muffler chamber  180 S reduces the pressure pulsation of the discharged refrigerant gas. Moreover, a first discharge-valve limiter  201 S is arranged on the first discharge valve  200 S and is fixed with a rivet together with the first discharge valve  200 S to limit the deflection opening amount of the first discharge valve  200 S. The first discharge opening  190 S, the first discharge valve  200 S, and the first discharge-valve limiter  201 S compose a first discharge valve portion of the lower end plate  160 S. 
     As illustrated in  FIG. 1 , an upper muffler cover  170 T is arranged on the upper side of the upper end plate  160 T such that the upper muffler chamber  180 T is formed between the upper muffler cover  170 T and the upper end plate  160 T. A second discharge opening  190 T (see  FIG. 2 ), which causes the second compression chamber  1331  of the second cylinder  121 T and the upper muffler chamber  180 T to communicate with each other, is provided near the second vane  127 T of the upper end plate  160 T. A reed valve type second discharge valve  200 T, which prevents backflow of the compressed refrigerant gas, is arranged at the second discharge opening  1901 . Moreover, a second discharge-valve limiter  201 T is arranged on the second discharge valve  200 T and is fixed with a rivet together with the second discharge valve  200 T to limit the deflection opening amount of the second discharge valve  200 T. The upper muffler chamber  180 T reduces the pressure pulsation of the discharged refrigerant. The second discharge opening  190 T, the second discharge valve  200 T, and the second discharge-valve limiter  2011  compose a second discharge valve portion of the upper end plate  160 T. The details of the first and second discharge valve portions will be described later. 
     The first cylinder  121 S, the lower end plate  160 S, the lower muffler cover  170 S, the second cylinder  121 T, the upper end plate  160 T, the upper muffler cover  170 T, and the intermediate partition plate  140  are fastened together by using a plurality of through bolts  175  or the like. In the compressing unit  12  formed by fastening the above components together by using the through bolts  175  or the like, the outer peripheral portion of the upper end plate  160 T is secured to the compressor housing  10  by spot welding, whereby the compressing unit  12  is fixed to the compressor housing  10 . 
     First and second through holes  101  and  102  are provided in the outer peripheral wall of the cylindrical compressor housing  10  such that they are axially spaced apart from each other. The first and second through holes  101  and  102  are arranged sequentially from the lower portion in the order such that first and second suction pipes  104  and  105  pass through the first and second through holes  101  and  102 , respectively. Moreover, an accumulator  25  composed of an independent cylindrical airtight container is held on the outside portion of the compressor housing  10  by an accumulator holder  252  and an accumulator band  253 . 
     A connection pipe  255  connected to an evaporator in the refrigeration cycle is connected to the center of the top of the accumulator  25 , and first and second low-pressure communication pipes  31 S and  31 T are connected to bottom-portion through holes  257  provided in the bottom portion of the accumulator  25 . One end of each of the first and second low-pressure communication pipes  31 S and  31 T extends to the upper portion in the accumulator  25 , and the other end of each of the first and second low-pressure communication pipes  31 S and  31 T is connected to the first and second suction pipes  104  and  105 , respectively. 
     The first and second low-pressure communication pipes  31 S and  31 T, which introduce low-pressure refrigerant in a refrigeration cycle to the first and second compressing units  12 S and  12 T via the accumulator  25 , are connected to the first and second suction openings  135 S and  135 T (see  FIG. 2 ) in the first and second cylinders  121 S and  121 T via the first and second suction pipes  104  and  105  that are suction units, respectively. In other words, the first and second suction openings  135 S and  135 T are connected to the evaporator in the refrigeration cycle in parallel. 
     A discharge pipe  107  as a discharge unit is connected to the top of the compressor housing  10 . The discharge pipe  107  is connected to the refrigeration cycle and discharges high-pressure refrigerant gas toward the condenser in the refrigeration cycle. In other words, the first and second discharge openings  190 S and  190 T are connected to the condenser in the refrigeration cycle. 
     Lubricating oil is encapsulated up to about the height of the second cylinder  121 T in the compressor housing  10 . Moreover, lubricating oil is pumped from an oil supply pipe  16  attached to the lower end portion of the rotating shaft  15  by a vane pump (not shown) inserted into the lower portion of the rotating shaft  15  and circulates in the compressing unit  12 , thereby lubricating sliding parts and sealing the minute gaps in the compressing unit  12 . 
     Next, an explanation will be given of the first and second discharge valve portions, which are characteristic configurations of the rotary compressor  1  in the embodiment, with reference to  FIG. 3  to  FIG. 6 .  FIG. 3  is a partial plan view of the upper and lower end plates to which the first and second discharge valves and the first and second discharge-valve limiters according to the embodiment are attached, respectively.  FIG. 4  is a partial cross-sectional view taken along line A-A in  FIG. 3 .  FIG. 5  is a partial cross-sectional view taken along line B-B in  FIG. 3 .  FIG. 6  is also a partial cross-sectional view taken along line B-B in  FIG. 3  similar to  FIG. 5 .  FIG. 6  illustrates a state where the first and second discharge-valve limiters are deflected by swaging. 
     As illustrated in  FIG. 3  to  FIG. 6 , first and second groove portions  163 S and  163 T are formed in the lower end plate  1605  and the upper end plate  160 T of the compressing unit  12  (see  FIG. 1 ) of the rotary compressor  1 , respectively. The first and second groove portions  163 S and  163 T accommodate the reed valve type first and second discharge valves  200 S and  200 T that open and close the first and second discharge openings  190 S and  190 T (see  FIG. 4 ) and the first and second discharge-valve limiters  201 S and  201 T, respectively. Furthermore, the first and second groove portions  163 S and  163 T are formed such that the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  2011  are attached to the bottom portions thereof with first and second rivets  203 S and  2031 , respectively. 
     The diameter (width) of the first and second groove portions  163 S and  163 T is enlarged on the side of the first and second discharge openings  190 S and  190 T so as to form first and second discharge-opening-side enlarged diameter portions  163 Sb and  163 Tb, respectively. The diameter (width) of the first and second groove portions  163 S and  163 T is also enlarged on the side of the first and second rivets  203 S and  203 T so as to form first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta, respectively. 
     As illustrated in  FIG. 5 , the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  201 T are attached to the bottom portions of the first and second groove portions  163 S and  163 T with the first and second rivets  203 S and  203 T, respectively. At this time, the first and second rivets  203 S and  203 T are inserted into first and second rivet holes  191 S and  191 T of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta and the rivet holes of the first and second discharge valves  200 S and  200 T and the first and second discharge-valve limiters  201 S and  201 T, respectively. 
     The diameter (width) of the first and second discharge-opening-side enlarged diameter portions  163 Sb and  163 Tb is enlarged. Therefore, a path is formed for compressed refrigerant gas that pushes open the reed valve type first and second discharge valves  200 S and  200 T and is discharged or ejected from the first and second discharge openings  190 S and  190 T, respectively. Step portions  163 Sbb and  163 Tbb are formed in the first and second discharge-opening-side enlarged diameter portions  163 Sb and  163 Tb on the side opposite to the side on which the first and second rivets  203 S and  203 T are inserted, respectively, whereby the flow path is further enlarged toward the side opposite to the first and second rivet side. 
     As illustrated in  FIG. 5 , the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta of the first and second groove portions  163 S and  163 T are each formed into a semicircular shape with a step (hereinafter, semicircular step), when viewed from openings of the first and second groove portions  163 S and  163 T toward the bottoms thereof, such that the bottom side has smaller diameter (width) than portions other than the bottom side. The diameter (width) Hd of the bottom side of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta is about 0.2 mm larger than the width of the first and second discharge-valve limiters  201 S and  201 T. 
     The diameter (width) Ha of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta other than the bottom side is 30 to 40% larger than the diameter (width) Hd of the bottom side. Therefore, when the punch P (see  FIG. 9 ) is caused to perform a rosette-like axial motion (motion of moving on a conical petal-like trajectory Y) about the central axis Z of the first and second rivets  203 S and  203 T in order to swage first and second swaging portions  203 Sa and  203 Ta by a swage, the punch P does not interfere with the inner wall portions of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta. 
     The width t s  of the bottom portions of the first and second groove portions  163 S and  163 T (including the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta and the first and second discharge-opening-side enlarged diameter portions  163 Sb and  163 Tb) are made as thin as possible so as to prevent backflow of the compressed refrigerant gas trapped in the first and second discharge openings  190 S and  190 T (see  FIG. 4 ) toward the first and second operating chambers  130 S and  130 T (see  FIG. 2 ) and to prevent the volumetric efficiency of refrigerant compression from decreasing. 
     As illustrated in  FIG. 5 , when h m  is the depth down to the bottom portion of the first and second groove portions  163 S and  163 T (including the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta), h z  is the depth down to step portions  163 Saa and  163 Taa of the semicircular step of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta, t v  (see  FIG. 4 ) is the thickness of the first and second discharge valves  200 S and  200 T, and t o  is the thickness of the first and second discharge-valve limiters  201 S and  201 T, the relationship h m −(t v +0.4t o )≧h z ≧h m −(t v +0.8t o ) is satisfied. In other words, the height from the bottom portions of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta to the step portions  163 Saa and  163 Taa is a height that is 40 to 80% of the thickness t o  of the first and second discharge-valve limiters  201 S and  201 T (the thickness t v  of the first and second discharge valves  200 S and  200 T is small and therefore may be negligible). 
     According to the configurations of the first and second discharge valve portions in the embodiment described above, the diameter (width) Hd of the bottom side of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta is reduced to be substantially equal to the width of the first and second discharge-valve limiters  201 S and  201 T. Therefore, when the first and second swaging portions  203 Sa and  203 Ta of the first and second rivets  203 S and  203 T are swaged by using the punch P, even if a swage load is applied, there is no bending stress and therefore the bottom portion is not deflected. 
     Moreover, because the diameter (width) Ha of the portions of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta other than the bottom side is made larger than the diameter (width) Hd of the bottom side by 30 to 40%, a rosette-like axial motion of the punch can be performed by a swage. 
     Moreover, as illustrated in  FIG. 6 , when the first and second swaging portions  203 Sa and  203 Ta of the first and second rivets  203 S and  203 T are swaged by using the punch P, even if upper portions  201 Sa and  201 Ta of the first and second discharge-valve limiters  201 S and  201 T are collapsed and protrude to the side portion, because the upper portions  201 Sa and  201 Ta are located above the step portions  163 Saa and  163 Taa of the semicircular step of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta, the lower end plates  160 S and  160 T are not deflected by pushing the inner walls of the first and second rivet-side enlarged diameter portions  163 Sa and  163 Ta apart. 
     An explanation has been given above of the twin rotary compressor  1  that includes the first and second compressing units  12 S and  12 T as the embodiment of the present invention; however, the present invention can be applied also to a single rotary compressor that includes one compressing unit, a two-stage compression rotary compressor that further compresses refrigerant discharged from a first compressing unit by a second compressing unit, or the like. 
     According to the present invention, an effect is obtained where a rosette-like axial motion of a punch can be performed by a swage and the bottom portions of the first and second rivet-side enlarged diameter portions are not deflected. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.