Hermetic compressor

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 MA represented by the following equation (1) is defined as a second moment of area,
• [
• Equation
• 
• 
• 1
• ]
• M
• A
• =
• ∫
• A
• 
• r
• 2
• 
• 
• A
• (
• 1
• )
• 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.