Hermetic compressor

Abstract

A hermetic compressor ( 100 ) includes a closed casing ( 2 ), a compression mechanism ( 4 ), a motor ( 6 ), a discharge pipe ( 8 ), a first balance weight ( 18 ), a swirl flow generating portion ( 21 ), and a second balance weight ( 19 ). The motor ( 6 ) has a stator ( 14 ) and a rotor ( 15 ). A communication passage ( 20 ) is formed in the rotor ( 15 ) so as to introduce, into an upper space ( 7 ), a working fluid compressed in the compression mechanism ( 4 ) and discharged to a lower space ( 5 ) of the closed casing ( 2 ). A baffle plate ( 122 ) is provided as a discharge direction deflecting portion for causing the compressed working fluid to travel from the communication passage ( 20 ) to the upper space ( 7 ), while deflecting the working fluid in a direction inclined with respect to a direction parallel to a rotational axis O. The baffle plate ( 122 ) may be constituted by a part of the swirl flow generating portion ( 21 ).

1 . A hermetic compressor comprising:
 a closed casing having an oil reservoir in its bottom portion;
 a compression mechanism, disposed in the closed casing, for compressing a working fluid; 
 a motor, disposed above the compression mechanism in the closed casing, for driving the compression mechanism, the motor having a rotor and a stator; 
 an upper space, formed above the motor, as a part of an internal space of the closed casing; 
 a lower space, formed between the motor and the compression mechanism, as a part of the internal space of the closed casing; 
 a discharge pipe opening into the upper space, for discharging the compressed working fluid outside the hermetic compressor; 
 a first balance weight protruding from an upper surface of the rotor toward the upper space; 
 a swirl flow generating portion protruding from the upper surface of the rotor toward the upper space, the swirl flow generating portion being disposed at a position closer to a rotational axis of the motor than the first balance weight; 
 a second balance weight protruding from a lower surface of the rotor toward the lower space; and 
 a communication passage formed in the rotor so as to introduce, into the upper space, the working fluid compressed in the compression mechanism and discharged to the lower space, wherein 
 when a three-dimensional annular trajectory of the first balance weight formed around the rotational axis when the motor is driven is defined as a first trajectory, a plane obtained by cutting the first trajectory with a first plane parallel to the rotational axis and including the rotational axis is defined as a first cross section, a three-dimensional annular trajectory of the second balance weight formed around the rotational axis when the motor is driven is defined as a second trajectory, a plane obtained by cutting the second trajectory with a second plane parallel to the rotational axis and including the rotational axis is defined as a second cross section, a three-dimensional annular trajectory of the swirl flow generating portion formed around the rotational axis when the motor is driven is defined as a third trajectory, a plane obtained by cutting the third trajectory with a third plane parallel to the rotational axis and including the rotational axis is defined as a third cross section, an area of a micro-region included in a specific region on an arbitrary plane parallel to the rotational axis and including the rotational axis is defined as dA, a distance from the rotational axis to a centroid of the micro-region is defined as r, and a value M A  represented by the following equation (1) is defined as a second moment of area, 
   
       
         
           
             
               
                 
                   
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       a sum of a second moment of area of the first cross section and a second moment of area of the third cross section is greater than a second moment of area of the second cross section, and
 the hermetic compressor further comprises a discharge direction deflecting portion for causing the compressed working fluid to travel from the communication passage to the upper space, while deflecting the working fluid in a direction inclined with respect to a direction parallel to the rotational axis. 
 
     
     
         2 . The hermetic compressor according to  claim 1 , wherein the swirl flow generating portion is also used as the discharge direction deflecting portion. 
     
     
         3 . The hermetic compressor according to  claim 1 , wherein the discharge direction deflecting portion is configured to direct the compressed working fluid in a direction opposite to a rotational direction of the rotor. 
     
     
         4 . The hermetic compressor according to  claim 2 , wherein
 the swirl flow generating portion includes, as the discharge direction deflecting portion, a baffle plate protruding from the upper surface of the rotor toward the upper space, and   an image obtained by projecting the baffle plate onto the upper surface of the rotor overlaps an outlet of the communication passage.   
     
     
         5 . The hermetic compressor according to  claim 1 , wherein
 an outlet part of the communication passage extends in the direction inclined with respect to the direction parallel to the rotational axis so that the compressed working fluid travels from the communication passage to the upper space, while being deflected in a direction that is opposite to a rotational direction of the rotor and is inclined with respect to the direction parallel to the rotational axis, and   the discharge direction deflecting portion is constituted by the outlet part.   
     
     
         6 . The hermetic compressor according to  claim 5 , wherein
 the swirl flow generating portion includes a baffle plate protruding obliquely from the upper surface of the rotor so as to extend in the same direction as the outlet part, and   an image obtained by projecting the baffle plate onto the upper surface of the rotor overlaps an outlet of the communication passage.   
     
     
         7 . The hermetic compressor according to  claim 1 , further comprising a swirl flow suppressing portion for reducing an area of a displacement surface of the second balance weight, the displacement surface displacing the working fluid. 
     
     
         8 . The hermetic compressor according to  claim 7 , wherein the swirl flow suppressing portion is constituted by a cover that covers the second balance weight so that the area of the displacement surface of the second balance weight is zero, the displacement surface displacing the working fluid. 
     
     
         9 . The hermetic compressor according to  claim 8 , wherein the cover is formed integrally with an end plate for clamping and fixing constituent elements of the rotor. 
     
     
         10 . The hermetic compressor according to  claim 7 , wherein
 the swirl flow suppressing portion is provided along a rotational trajectory of the second balance weight, and   the swirl flow suppressing portion has a smaller specific gravity than the second balance weight.   
     
     
         11 . The hermetic compressor according to  claim 10 , wherein the swirl flow suppressing portion is made of a material having voids into which the working fluid containing oil particles can penetrate.