US20080145247A1

US20080145247A1 - Hermetic compressor

Info

Publication number: US20080145247A1
Application number: US11/891,096
Authority: US
Inventors: Jong In Park
Original assignee: Samsung Gwangju Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2006-12-18
Filing date: 2007-08-09
Publication date: 2008-06-19
Also published as: KR20080056343A; KR101235191B1

Abstract

A hermetic compressor including a drive unit, a piston, a rotating shaft including an eccentric shaft portion and a weight balance portion located below the eccentric shaft portion, and an oil flow path having an upper oil hole formed in the rotating shaft and adapted to allow oil to be suctioned upward and dispersed to the upper side of the eccentric shaft portion and an auxiliary oil hole to allow a part of the oil being suctioned upward along the upper oil hole to be supplied into a gap between the eccentric shaft portion and the connecting rod. The eccentric shaft portion is installed with a plug member to close an upper end of the upper oil hole. The plug member is configured to selectively couple a weight balance member, which is separately fabricated from the rotating shaft, to an upper end of the eccentric shaft portion.

Description

CROSS-REFERENCE TO RELATED APPLICATION

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.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

Therefore, it is an aspect of the disclosure to provide a hermetic compressor which can achieve not only efficient oil lubrication between a connecting rod and an eccentric shaft portion of a rotating shaft, but also easy installation of an additional weight balance member to the rotating shaft, by providing the rotating shaft with a relatively simple configuration.
In accordance with an aspect, the present disclosure provides a hermetic compressor comprising: a drive unit; a piston to compress a refrigerant upon receiving power from the drive unit; a rotating shaft adapted to be rotated during operation of the drive unit and including an eccentric shaft portion provided at an upper end thereof so as to be connected to the piston via a connecting rod and a weight balance portion located below the eccentric shaft portion so as to compensate for rotation unbalance caused by the eccentric shaft portion; and an oil flow path having an upper oil hole formed in the rotating shaft and adapted to allow oil to be suctioned upward and dispersed to the upper side of the eccentric shaft portion and an auxiliary oil hole to allow a part of the oil suctioned upward along the upper oil hole to be supplied into a gap between the eccentric shaft portion and the connecting rod, wherein the eccentric shaft portion is installed with a plug member to close an upper end of the upper oil hole, and the plug member is configured to selectively couple a weight balance member, which is separately fabricated from the rotating shaft, to an upper end of the eccentric shaft portion.
The plug member may comprise a fastening portion formed, at an outer periphery thereof, with a male screw, and a female screw may be processed at an inner periphery of an upper portion of the upper oil hole so as to define a fastening hole for the coupling of the fastening portion.
The plug member may further comprise a plug portion provided at a top of the fastening portion and configured to come into close contact with the upper end of the eccentric shaft portion around the upper oil hole, for closing the upper oil hole, and the weight balance member may have a coupling hole for penetration of the fastening portion. Also, the weight balance member may be secured between the upper end of the eccentric shaft portion and the plug portion as the fastening portion, penetrating the coupling hole, is fastened to the fastening hole.
Lengths of the fastening portion and the fastening hole may be determined such that the plug portion comes into close contact with the upper end of the eccentric shaft portion even in a state in which the weight balance member is removed.
The connecting rod may comprise a large-diameter portion configured to enclose the eccentric shaft portion, the connecting rod being connected to the eccentric shaft portion via the large-diameter portion, and an upper end of the large-diameter portion may be spaced apart from a lower end of the weight balance member.
The plug member may be a fixing bolt.
Additional aspects and/or advantages of the hermetic compressor will be set forth in part in the description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a sectional view illustrating the general configuration of an exemplary embodiment of a hermetic compressor;

FIG. 2 is a detailed view of a part of FIG. 1, illustrating the mounting structure of a plug member into an eccentric shaft portion of a rotating shaft;

FIG. 3 is an exploded perspective view illustrating the plug member, which is separated from the eccentric shaft portion of the rotating shaft, in the hermetic compressor;

FIG. 4 is an exploded perspective view illustrating the coupling structure of a weight balance member using the plug member, in the hermetic compressor; and

FIG. 5 is a sectional view illustrating the coupling structure of the weight balance member using the plug member, in the hermetic compressor.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Reference will now be made in detail to an exemplary embodiment of a hermetic compressor, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiment is described below by referring to the figures.
As shown in FIG. 1, the hermetic compressor includes a hermetic container 1 formed by coupling an upper container 1 a and a lower container 1 b to each other, the hermetic container 1 defining the outer appearance of the compressor. The hermetic container 1 is provided, at opposite sides thereof, with a suction pipe 1 c to guide a refrigerant, passed through an evaporator of a refrigeration cycle, into the hermetic container 1 and with a discharge pipe 1 d to guide the refrigerant, compressed within the hermetic container 1, to a condenser of the refrigeration cycle.
Provided within the hermetic container 1 are a drive unit 10 to provide power required to compress a refrigerant and a compressing unit 20 to compress the refrigerant upon receiving the power of the drive unit 10. Both the drive unit 10 and the compressing unit 20 are installed via a frame 30.
The drive unit 10 includes a stator 11 secured around a lower portion of the frame 30, and a rotor 12 provided inside the stator 11 and adapted to be rotated via electromagnetic interaction with the stator 11. To transmit the power of the drive unit 10 to the compressing unit 20, a rotating shaft 40 is installed to penetrate the center of the frame 30 and the rotor 12.
The rotating shaft 40, inside the rotor 12, is press-fitted in the center of the rotor 12, so as to be rotated together with the rotor 12. The frame 30 centrally defines a hollow portion 31 to rotatably support the rotating shaft 40 therein. Here, an upper end of the rotating shaft 40, protruding upward from the frame 30, defines an eccentric shaft portion 41 to be eccentrically rotated, and a portion of the rotating shaft 40 right below the eccentric shaft portion 41 defines a weight balance portion 42 to compensate for rotation unbalance of the rotating shaft 40 caused by the eccentric shaft portion 41. The weight balance portion 42 is located right above the hollow portion 31. Both the eccentric shaft portion 41 and the weight balance portion 42 are integrally formed with the rotating shaft 40 in the course of forming the rotating shaft 40.
The compressing unit 20 includes a cylinder 21 integrally formed on the top of the frame 30 at the outside of the eccentric shaft portion 41, the cylinder 21 defining a compressing chamber 21 a therein, and a piston 22 to perform rectilinear reciprocation motion in the compressing chamber 21 a.
An end of the piston 22 toward the eccentric shaft portion 41, which is a leading end in a rearward movement of the piston 22, is connected to the eccentric shaft portion 41 by a connecting rod 23 such that the piston 22 rectilinearly reciprocates in the compressing chamber 21 a when the eccentric shaft portion 41 performs eccentric rotating motion by rotation of the rotating shaft 40.
The connecting rod 23 has a large-diameter portion 23 a and a small-diameter portion 23 b formed, respectively, at opposite ends thereof, which are connected to each other by an intermediate connecting portion 23 c. As the large-diameter portion 23 a is rotatably fitted around the eccentric shaft portion 41, the connecting rod 23 is connected to the eccentric shaft portion 41. Also, as the small-diameter portion 23 b is inserted into the piston 22 and rotatably fastened to a piston pin 22 a that is previously fastened to the piston 22, the connecting rod 23 is connected to the piston 22.
A cylinder head 24 is coupled to an end of the cylinder 21, which is a leading end in a forward movement of the piston 22, to hermetically seal the compressing chamber 21 a. The cylinder head 24 defines a refrigerant suction chamber 24 a and a refrigerant discharge chamber 24 b therein, which are separated from each other.
Here, the refrigerant suction chamber 24 a serves to guide the refrigerant, introduced into the hermetic container 1 through the suction pipe 1 c, into the compressing chamber 21 a. The refrigerant discharge chamber 24 b serves to guide the refrigerant, compressed in the compressing chamber 21 a, into the discharge pipe 1 d. A valve device 25 is interposed between the cylinder 21 and the cylinder head 24 and adapted to control the flow of the refrigerant being suctioned from the refrigerant suction chamber 24 a into the compressing chamber 21 a or being discharged from the compressing chamber 21 a into the refrigerant discharge chamber 24 b.
In the above described configuration, if the rotating shaft 40 is rotated together with the rotor 12 via electromagnetic interaction between the stator 11 and the rotor 12, the piston 22, which is connected to the eccentric shaft portion 41 via the connecting rod 23, rectilinearly reciprocates in the compressing chamber 21 a, thereby creating a pressure difference between the interior and the exterior of the compressing chamber 21 a. With the pressure difference, a refrigerant, which is guided into the hermetic container 1 along the suction pipe 1 c from the evaporator of the refrigeration cycle, is suctioned into the compressing chamber 21 a by way of the refrigerant suction chamber 24 a. Also, the refrigerant, which is compressed in and discharged from the compressing chamber 21 a, is delivered toward the condenser of the refrigeration cycle by way of the refrigerant discharge chamber 24 b and the discharge pipe 1 d.
An oil storage space 1 e for storing a predetermined amount of oil is defined in a bottom region of the hermetic container 1. Also, an oil flow path 50 is formed at the rotating shaft 40 such that oil in the oil storage space 1 e is suctioned upward through a gap between the rotating shaft 40 and the frame 30 under the influence of a centrifugal force of the rotating shaft 40.
The oil flow path 50 includes a lower oil hole 51 formed in a lower portion of the rotating shaft 40, an oil groove 52 spirally formed at an outer surface of the rotating shaft 40 at a position corresponding to the hollow portion 31 of the frame 30, a lower end of the oil groove 52 communicating with the lower oil hole 51, and an upper oil hole 53 extended from an upper end of the oil groove 52 to an upper end of the eccentric shaft portion 41 through the interior of the rotating shaft 40. An auxiliary oil hole 54 is branched from the upper oil hole 53, to supply the oil into a gap between an inner surface of the large-diameter portion 23 a of the connecting rod 23 and an outer surface of the eccentric shaft portion 41.
An oil pickup member 61 is press-fitted in a lower end of the rotating shaft 40, to raise the oil in the oil storage space 1 e into the oil flow path 50 by use of a centrifugal force generated via rotation of the rotating shaft 40, and in turn an oil pickup blade 62 is installed in the oil pickup member 61.
With the above described configuration, as the rotating shaft 40 is rotated for the compression of a refrigerant, the oil, stored in the oil storage space 1 e, is suctioned upward by way of the lower oil hole 51, oil groove 52, and upper oil hole 53 in sequence by the centrifugal force of the rotating shaft 40. In this case, between the rotating shaft 40 and the hollow portion 31 of the frame 30 is lubricated by the oil passing through the oil groove 52, and between the connecting rod 23 and the eccentric shaft portion 41 is lubricated by the oil supplied through the auxiliary oil hole 54. The configuration of the rotating shaft 40 including the upper and lower oil holes 53 and 51, oil groove 52, and auxiliary oil hole 54 is identical to that of the above described conventional hermetic compressor.
As shown in FIGS. 2 and 3, in the present embodiment, a plug member 70 is coupled into the eccentric shaft portion 41, for the purpose of preventing the oil from being dispersed upward through the eccentric shaft portion 41.
The plug member 70 is configured to close an upper end of the upper oil hole 53, so as to allow all the oil, guided into the upper oil hole 53, to be supplied into the gap between the eccentric shaft portion 41 and the large-diameter portion 23 a of the connecting rod 23 through the auxiliary oil hole 54. The use of the plug member 70 has the effect of guaranteeing more active lubrication between the eccentric shaft portion 41 and the connecting rod 23, and consequently restricting wear of the eccentric shaft portion 41 and the connecting rod 23.
As shown by the solid-line arrows in FIG. 2, only a part of the oil, which is supplied into the gap between the eccentric shaft portion 41 and the large-diameter portion 23 a of the connecting rod 23 through the auxiliary oil hole 54, is supplied toward the piston 22 and the cylinder 21 through the narrow gap between the eccentric shaft portion 41 and the large-diameter portion 23 a. In one exemplary embodiment, accordingly, the amount of oil to be supplied toward the piston 22 or cylinder 21 is reduced as compared to the prior art, and consequently the amount of oil to be introduced into the compressing chamber 21 a is reduced. This has the effect of improving the compression efficiency of a refrigerant.
More specifically, the plug member 70 includes a fastening portion 71 formed with a male screw, and a plug portion 72 provided on a top of the fastening portion 71 for closing the upper oil hole 53, the plug portion 72 being configured to come into close contact with the upper end of the eccentric shaft portion 41 around the upper oil hole 53. The upper oil hole 53 is formed, at an inner periphery of an upper portion thereof, with a female screw, so as to define a fastening hole 53 a for allowing the fastening portion 71 to be screwed into the upper oil hole 53.
Accordingly, if the fastening portion 71 of the plug member 70 is screwed into the fastening hole 53 a, the upper oil hole 53 is closed by the plug portion 72 and the plug member 70 is coupled into the eccentric shaft portion 41. Thereby, the upper end of the upper oil hole 53 is closed, so all the oil, guided into the upper oil hole 53, is supplied into the gap between the eccentric shaft portion 41 and the large-diameter portion 23 a along the auxiliary oil hole 54. Here, it will be appreciated that the plug member 70 may be a conventional fixing bolt.
The oil, discharged from the auxiliary oil hole 54 under the use of the plug member 70, is used to lubricate between the eccentric shaft portion 41 and the large-diameter portion 23 a and between the piston 22 and the cylinder 21, and then falls down, to thereby be returned into the oil storage space 1 e. The returned oil can be again suctioned upward along the oil flow path 50, so as to repeat the above described lubrication course.
Meanwhile, in relation with the weight balance portion 42, there is often a risk that the weight of the weight balance portion 42 is too small to compensate for rotation unbalance of the rotating shaft 40. In this case, it is necessary to additionally couple a weight balance member 80, which is separately fabricated from the rotating shaft 40, to the rotating shaft 40. In an exemplary embodiment of the hermetic compressor, with the use of the plug member 70, the weight balance member 80 can be easily coupled to the rotating shaft 40 without interference with the operation of the connecting rod 23.
Specifically, as shown in FIGS. 4 and 5, in the present embodiment, the weight balance member 80, configured to be coupled to the rotating shaft 40, has a plate shape, and includes a mass portion 81 having a large width, which is defined at one side of the weight balance member 80, and a coupling portion 82 having a width smaller than that of the mass portion 81, which is defined at the other side of the weight balance member 80. The coupling portion 82 is perforated with a coupling hole 82 a for the coupling of the fastening portion 71 of the plug member 70.
Accordingly, in a state in which the fastening portion 71 of the plug member 70 is inserted into the coupling hole 82 a of the weight balance member 80, the fastening portion 71 is screwed into the fastening hole 53 a processed in the eccentric shaft portion 41. Thereby, as the fastening portion 71, penetrating the coupling hole 82 a, is fastened into the fastening hole 53 a, the weight balance member 80 can be secured simply between the upper end of the eccentric shaft portion 41 and the plug portion 72.
In this case, the weight balance member 80, which is secured to the upper end of the eccentric shaft portion 41, does not interfere with the operation of the connecting rod 23. Of course, there is a risk that the operation of the connecting rod 23 may be hindered by the weight balance member 80 in the case where a lower end of the weight balance member 80 comes into contact with an upper end of the large-diameter portion 23 a of the connecting rod 23. Therefore, it is preferable that the lower end of the weight balance member 80 be spaced apart from the upper end of the large-diameter portion 23 a.
Also, it is preferable that a length of the fastening hole 53 a, processed in the upper portion of the upper oil hole 53, and a length of the fastening portion 71 of the plug member 70 be determined to allow a lower end of the plug portion 72 to come into close contact with the upper end of the eccentric shaft portion 41 under the assumption that no weight balance member 80 is provided. This is to prevent failure in the closing operation of the upper oil hole 53. If the fastening hole 53 a has a somewhat short length, the lower end of the plug portion 72 and the upper end of the eccentric shaft portion 41 may have a gap therebetween in a state in which the weight balance member 80 is removed, and this hinders the upper oil hole 53 from being completely closed.
The above described hermetic compressor according to the present embodiment has approximately the same configuration as that of the previously described conventional hermetic compressor except for the plug member 70 and the fastening hole 53 a processed in the upper portion of the upper oil hole 53. Accordingly, by a simplified operation for processing a female screw in the upper portion of the upper oil hole of the rotating shaft included in the conventional hermetic compressor for the purpose of forming the fastening hole 53 a, and installing the plug member 70 in the fastening hole 53 a, the hermetic compressor according to the present embodiment can increase the lubrication efficiency between the connecting rod 23 and the eccentric shaft portion 41, and facilitate the installation of the weight balance member 80. Therefore, the present embodiment can eliminate any troublesome work of newly fabricating the rotating shaft 40 by use of a new mold, and is advantageous in view of costs.
As apparent from the above description, according to an exemplary embodiment of a hermetic compressor, by only a simple operation for processing an eccentric shaft portion of a rotating shaft and installing a plug member in the eccentric shaft portion, it is possible to achieve a considerable improvement in oil lubrication between the eccentric shaft portion and a connecting rod, and also to facilitate the installation of a weight balance member that is separately fabricated and coupled to the rotating shaft.
Although an embodiment of a hermetic compressor has been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.

Claims

1. A hermetic compressor comprising:

a drive unit;

a piston to compress a refrigerant upon receiving power from the drive unit;

a rotating shaft adapted to be rotated during operation of the drive unit and including an eccentric shaft portion provided at an upper end thereof so as to be connected to the piston via a connecting rod and a weight balance portion located below the eccentric shaft portion so as to compensate for rotation unbalance caused by the eccentric shaft portion; and

an oil flow path having an upper oil hole formed in the rotating shaft and adapted to allow oil to be suctioned upward and dispersed to the upper side of the eccentric shaft portion and an auxiliary oil hole to allow a part of the oil suctioned upward along the upper oil hole to be supplied into a gap between the eccentric shaft portion and the connecting rod,

wherein the eccentric shaft portion is installed with a plug member to close an upper end of the upper oil hole, and the plug member is configured to selectively couple a weight balance member, which is separately fabricated from the rotating shaft, to an upper end of the eccentric shaft portion.

2. The hermetic compressor according to claim 1, wherein the plug member comprises a fastening portion formed, at an outer periphery thereof, with a male screw, and a female screw is processed at an inner periphery of an upper portion of the upper oil hole so as to define a fastening hole for the coupling of the fastening portion.

3. The hermetic compressor according to claim 2,

wherein the plug member further comprises a plug portion provided at a top of the fastening portion and configured to come into close contact with the upper end of the eccentric shaft portion around the upper oil hole, for closing the upper oil hole,

wherein the weight balance member has a coupling hole for penetration of the fastening portion, and

wherein the weight balance member is secured between the upper end of the eccentric shaft portion and the plug portion as the fastening portion, penetrating the coupling hole, is fastened to the fastening hole.

4. The hermetic compressor according to claim 3, wherein lengths of the fastening portion and the fastening hole are determined such that the plug portion comes into close contact with the upper end of the eccentric shaft portion even in a state in which the weight balance member is removed.

5. The hermetic compressor according to claim 1, wherein the connecting rod comprises a large-diameter portion configured to enclose the eccentric shaft portion, the connecting rod being connected to the eccentric shaft portion via the large-diameter portion, and an upper end of the large-diameter portion is spaced apart from a lower end of the weight balance member.

6. The hermetic compressor according to claim 1, wherein the plug member is a fixing bolt.