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Hermetic compressor

Hermetic compressor description/claims

This application claims the benefit of Korean Patent Application No. 2006-0129124, filed on Dec. 18, 2006 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

1. Field of the Invention

The present disclosure relates to a hermetic compressor, and, more particularly, to a hermetic compressor which can achieve oil lubrication between an eccentric shaft portion of a rotating shaft and a connecting rod, and employ a weight balance member that is separately fabricated from the rotating shaft so as to be coupled to the rotating shaft as occasion demands, in addition to a weight balance portion integrally formed at the rotating shaft for compensating for rotation unbalance caused by the eccentric shaft portion.

2. Description of the Related Art

In general, a hermetic compressor is employed in a refrigeration cycle of a refrigerator or air conditioner, for the purpose of compressing a refrigerant. The hermetic compressor includes a hermetic container defining the outer appearance thereof.

The hermetic compressor further includes a drive unit to provide refrigerant compressive power and a compressing unit to compress a refrigerant upon receiving the power of the drive unit, both the drive unit and the compressing unit being arranged in the hermetic container.

The drive unit includes a stator and a rotor installed around a lower portion of a frame. To transmit the power of the drive unit to the compressing unit, a rotating shaft is installed to penetrate the center of the frame and the rotor.

The rotating shaft, inside the rotor, is press-fitted in the center of the rotor, so as to be rotated together with the rotor. The frame centrally defines a hollow portion to rotatably support the rotating shaft therein.

Here, an upper end of the rotating shaft, protruding upward from the frame, defines an eccentric shaft portion to be eccentrically rotated, and a portion of the rotating shaft right below the eccentric shaft portion defines a weight balance portion to compensate for rotation unbalance of the rotating shaft caused by the eccentric shaft portion.

The weight balance portion is located right above the hollow portion. Both the eccentric shaft portion and the weight balance portion are integrally formed with the rotating shaft in the course of forming the rotating shaft.

The compressing unit includes a compressing chamber and a piston to perform rectilinear reciprocating motion in the compressing chamber, for the purpose of compressing a refrigerant.

An end of the piston toward the eccentric shaft portion, which is a leading end in a rearward movement of the piston, is connected to the eccentric shaft portion by a connecting rod such that the piston rectilinearly reciprocates in the compressing chamber when the eccentric shaft portion performs eccentric rotating motion by rotation of the rotating shaft.

The connecting rod has a large-diameter portion and a small-diameter portion formed, respectively, at opposite ends thereof, which are connected to each other by an intermediate connecting portion. As the large-diameter portion is rotatably fitted around the eccentric shaft portion, the connecting rod is connected to the eccentric shaft portion. Also, as the small-diameter portion is inserted into the piston and rotatably fastened to a piston pin that is previously fastened to the piston, the connecting rod is connected to the piston.

With the above described configuration, if the rotating shaft is rotated together with the rotor via electromagnetic interaction between the stator and the rotor, the piston, which is connected to the eccentric shaft portion by the connecting rod, rectilinearly reciprocates in the compressing chamber, thereby performing the compression of a refrigerant.

In addition, an oil storage space for storing a predetermined amount of oil is defined in a bottom region of the hermetic container. An oil flow path is formed at the rotating shaft, to guide the oil in the oil storage space by way of a gap between the rotating shaft and the frame under the influence of a centrifugal force, for the dispersion of the oil to the upper side of the eccentric shaft portion.

The oil flow path includes a lower oil hole formed in a lower portion of the rotating shaft, an oil groove spirally formed at an outer surface of the rotating shaft at a position corresponding to the hollow portion of the frame, a lower end of the oil groove communicating with the lower oil hole, and an upper oil hole extended from an upper end of the oil groove to the upper end of the eccentric shaft portion through the interior of the rotating shaft. An auxiliary oil hole is branched from the upper oil hole, to supply the oil into a gap between an inner surface of the large-diameter portion of the connecting rod and an outer surface of the eccentric shaft portion.

With the above described configuration, as the rotating shaft is rotated for the compression of a refrigerant, the oil, stored in the oil storage space, is suctioned upward by way of the lower oil hole, oil groove, and upper oil hole in sequence by the centrifugal force of the rotating shaft, to thereby be dispersed to the upper side of the eccentric shaft portion. In this case, between the rotating shaft and the hollow portion of the frame is lubricated by the oil passing through the oil groove, and between the connecting rod and the eccentric shaft portion is lubricated as a part of the oil, passing the upper oil hole, is discharged through the auxiliary oil hole. Also, the oil, dispersed to the upper side of the eccentric shaft portion, is used to lubricate between the connecting rod and the piston and between the piston and the cylinder, etc.

However, in the above described conventional hermetic compressor, most of the oil, suctioned upward along the oil flow path, is dispersed to the upper side of the eccentric shaft portion along the oil flow path, and thus only a residual small amount of the oil is supplied via the auxiliary oil hole. This brings about a result of supplying an excessive amount of oil toward the cylinder and the piston, and causing the introduction of oil into the compressing chamber. When the oil is introduced into the compressing chamber, degradation in the compression efficiency of a refrigerant is inevitable, and it is difficult to supply a sufficient amount of oil into the gap between the connecting rod and the eccentric shaft portion, resulting in serious wear of the connecting rod.

Further, in the case of the conventional hermetic compressor, the weight of the weight balance portion may be too small to compensate for rotation unbalance of the rotating shaft. In this case, although it is necessary to couple a weight balance member, which is separately fabricated, to the rotating shaft, the coupling of the weight balance member to the rotating shaft is very difficult due to interference with the connecting rod.

To solve the above described problems, it may be considered to change the overall structure of the oil flow path in order to reduce the amount of oil to be dispersed through the upper oil hole, or may be considered to provide the rotating shaft with a coupling region for facilitating the coupling of the weight balance member. However, in this case, it is necessary to significantly change the shape and structure of the rotating shaft, and consequently to exchange a mold, etc. for the fabrication of the rotating shaft, resulting in enormous manufacturing costs.

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