Abstract:
A hermetic compressor casing is capable of reducing transmission of vibration to the outside environment by blocking the vibration from the compressor body. The hermetic compressor casing encloses a refrigerant compressing means, which draws in low temperature and low pressure gaseous refrigerant from an evaporator, compresses the drawn refrigerant and discharges the compressed refrigerant. The hermetic compressor casing includes an inner shell enclosing the refrigerant compressing means and having a passageway through which the gaseous refrigerant is drawn in and discharged out, a damping layer enclosing the exterior of the inner shell having a predetermined thickness, and an outer shell enclosing the exterior of the damping layer. As a result, vibration produced from the refrigerant compressing means is damped through the damping layer.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a hermetic compressor for use in a refrigerant cycle, and more particularly, to a casing of a hermetic compressor contributing to reduction of vibration and noise produced from the hermetic compressor. 
     2. Description of the Prior Art 
     Following a refrigerant cycle, a conventional hermetic compressor draws in low temperature and low pressure vapor refrigerant from an evaporator and compresses it into high temperature and high pressure vapor refrigerant, and then discharges the refrigerant to a condenser. 
       FIG. 1  shows the structure of such conventional hermetic compressor. Referring to  FIG. 1 , the hermetic compressor includes a motor, a cylinder, a casing  50  partitioning a compressor body  10  from the outside environment, and a supporting member  30  for supporting the compressor body  10 . The compressor body  10  contains therein a suction/discharge pipe and draws in and compresses refrigerant. 
     The motor is comprised of a stator  12  secured on the supporting member  30  and a rotor  14  rotating inside of the stator  12 . A rotary shaft  16  is mounted in and attached to the center of the rotor  14 , and an eccentric portion  18  is formed at the lower end of the rotary shaft  16 . 
     The cylinder includes a cylinder body  22  that defines a bore  23  for the refrigerant suction/compression, and a valve  26  disposed on the upper portion of the cylinder body  22  to control the refrigerant suction/discharge. A piston  24  is assembled in the cylinder body  22  to be reciprocally movable therein. The piston  24  is connected to a connecting rod  20  connected to the eccentric portion  18  that converts the rotary motion of the rotary shaft  16  into linear reciprocal motion. 
     The suction/discharge pipe  28  connects the valve  26  of the cylinder to the refrigerant cycle, and define a passageway through which refrigerant is drawn in and discharged out. 
     The supporting member  30  is disposed inside of a lower shell  54  of the casing  50  and supports the stator  12  and the cylinder body  22  of the motor, thereby partitioning the compressor body  10  off from the casing  50 . The supporting member  30  is formed of a spring so as to absorb vibration produced during a rotation of the eccentric portion  18  and reciprocal movement of the piston  24 . 
     The casing  50  encloses the compressor body  10  from outside, and is comprised of an upper shell  52  and the lower shell  54  for easy assembling. The supporting member  30  is disposed in the lower shell  54 , and the compressor body  10  is mounted on the supporting body  30 . The lower shell  54  has an aperture through which the suction/discharge pipe  28  extends. For simplicity of the fabricating process and strength of the casing  50 , the upper and lower shells  52  and  54  of the casing  50  are made by molding of a metal plate. The upper and lower shells  52  and  54  are connected to each other, for example, by welding. 
     When the supply of electricity is provided to the hermetic compressor constructed as above, the rotor  14  starts rotating. With the rotation of the rotor  14 , the rotary shaft  16 , which is integrally attached to the rotor  14 , also rotates. And, as the rotary shaft  16  rotates, the piston  24  starts reciprocating in the cylinder body  22  by motion of the eccentric portion  18  and the connecting rod  20  at the leading end of the rotary shaft  16 . By reciprocating the piston  24  inside of the bore  23 , the valve  26  is moved to permit the refrigerant to be drawn in through the suction/discharge pipe  28  for compression and to be discharged out to the refrigerant evaporator cycle. More specifically, as the piston  24  moves toward the lower dead end, the suction valve  29  opens, permitting the low temperature and low pressure gaseous refrigerant into the cylinder bore  23  via the suction pipe (not shown). Then as the piston  24  moves toward the upper dead end, the suction valve  29  closes, and the refrigerant in the bore  23  is compressed. After the compression of the refrigerant, the discharge valve  27  opens, permitting the compressed refrigerant to be discharged toward the condenser via the discharge pipe  28 . During the rotation of the rotary shaft  16 , the piston  24  keeps reciprocally moving up and down between the upper and lower dead ends, repeating the refrigerant cycle described above. 
     As described above, the rotor  14  rotates, and the rotary motion of the rotor  14  is converted to the reciprocal movement of the piston  24  by the eccentric portion  18  and the connecting rod  20  during the cycle of refrigerant suctioning, compressing and discharging in the compressor body  10 . Accordingly, a considerable amount of vibration and noise is produced. The supporting member  30  is provided for absorbing, and thus reducing, the vibration and noise from the compressor body  10 . However, the vibration and noise is not completely absorbed, thus annoying vibration and noise is transmitted to the outside via the casing  50 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a hermetic compressor casing having a multi-layer structure in which a damping layer is included to block vibration and noise, and thus reducing vibration and noise produced from a compressor body. 
     In order to accomplish the above object, in a hermetic compressor casing for enclosing a refrigerant compressing means that draws in low temperature and low pressure gaseous refrigerant from an evaporator, compresses the drawn refrigerant and discharges the compressed refrigerant, the hermetic compressor casing according to the present invention includes an inner shell enclosing the refrigerant compressing means and having a passageway through which the gaseous refrigerant is drawn in and discharged out; a damping layer enclosing the exterior of the inner shell having a predetermined thickness; and an outer shell enclosing the exterior of the damping layer, whereby vibration produced from the refrigerant compressing means is damped through the damping layer. 
     The inner shell, the damping layer and the outer shell are formed of an integral multi-layer plate. The inner shell and the outer shell are metal, and the damping layer preferably is a viscoelastic polymer. 
     Further, in order to accomplish the above object, in a hermetic compressor casing as described above according to the present invention includes a lower casing comprising an inner lower shell supporting the refrigerant compressing means and having a passageway through which the gaseous refrigerant is drawn in and discharged out, a lower damping layer enclosing the exterior of the inner lower shell having a predetermined thickness, an outer lower shell enclosing the exterior of the lower damping layer, and an upper casing enclosing an upper portion of the refrigerant compressing means, and assembled to connect with the lower casing, whereby vibration produced from the refrigerant compressing means is damped through the lower damping layer. 
     The upper casing comprises an inner upper shell made of a metal, an upper damping layer enclosing the inner upper shell having a predetermined thickness, and an outer upper shell enclosing the exterior of the upper damping layer. 
     The lower casing and the upper casing are formed as a multi-layer plate having a metal layer, a damping layer and a metal layer. 
     In one embodiment, the upper casing and the lower casing are assembled to connect to each other so that the upper damping layer and the inner lower shell contact each other. In another embodiment, the upper casing and the lower casing are assembled with each other so that the upper damping layer and the lower damping layer contact each other. 
     With the hermetic compressor casing according to the present invention, as the vibration and noise from the compressor body is damped through the damping layer of the casing, the amount of vibration and noise to the environment outside of the compressor casing can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned objects and the feature of the present invention will be made more apparent by describing the preferred embodiment of the present invention in detail referring to the appended drawings, in which: 
         FIG. 1  is a cross-sectional view showing a hermetic compressor having a conventional casing; 
         FIG. 2  is a cross-sectional view showing a hermetic compressor having a casing according to the present invention; 
         FIGS. 3A ,  3 B and  3 C are detail views showing an assembly portion of upper and lower casings of  FIG. 2  according to respective embodiment examples; 
         FIG. 4  is a detail view showing a multi-layer structure used for shaping the casing of  FIG. 2 ; 
         FIG. 5  is a comparison graph showing the amplitude comparison between the hermetic compressor using the casing of  FIG. 2  according to the present invention and the hermetic compressor using a conventional casing; and 
         FIG. 6  is a comparison graph showing the level of vibration between the hermetic compressor using the casing of  FIG. 2  according to the present invention and the hermetic compressor using a conventional casing. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention will be described in greater detail with reference to the accompanying drawings. Throughout the description, like elements with similar functions will be given the same reference numerals. 
     Referring to  FIG. 2 , the hermetic compressor according to the present invention includes a compressor body  10  having a motor, a cylinder and a suction/discharge pipe therein to draw in and compress the refrigerant, a casing  100  partitioning the compressor body  10  from the outside environment, and a supporting member  30  for supporting the compressor body  10  with respect to the casing  100 . 
     The motor includes a stator  12  secured to the supporting member  30  and a rotor  14  rotated inside of the stator  12 . A rotary shaft  16  is assembled in the center of the rotor  14 , and an eccentric portion  18  is formed at the lower end of the rotary shaft  16 , similar to the conventional compressor shown in FIG.  1 . 
     The cylinder includes a cylinder body  22  for defining a refrigerant suction/compression bore  23 , and a valve  26  disposed on the upper end of the cylinder body  22  to control suction and discharge of the refrigerant. A piston  24  is assembled within the cylinder body  22  to be reciprocally moved, and the piston  24  is connected to a connecting rod  20  for converting the rotary motion of the eccentric portion  18  of the rotary shaft  16  into reciprocal linear motion. 
     The suction/discharge pipes  28  connect the valve  26  of the cylinder to the refrigerant cycle, and serve as a passageway through which refrigerant is drawn into the cylinder and discharged out of bore  23 . 
     The supporting member  30  is disposed adjacent the inner lower shell  122  of the lower casing  120 , so as to support the stator  12  of the motor and the cylinder body  22  so that the compressor body  10  can be partitioned off from the casing  100 . The supporting member  30  preferably comprises a spring so as to absorb the vibration produced during the rotation of the eccentric portion  18  and the reciprocal movement of the piston  24 . 
     The casing  100  encloses the compressor body  10  from the outside, and is provided with lower and upper casings  120  and  110  for more convenient assembly. For more efficient reduction of vibration and noise, the casing  100  can be integrally formed. 
     Referring also now to  FIGS. 3A ,  3 B and  3 C, the lower casing  120  includes an inner lower shell  122 , a lower damping layer  124  and an outer lower shell  126 . The supporting member  30  is disposed on the inner lower shell  122 , while the compressor body  10  is mounted on the supporting member  30 . The inner lower shell  122  has a hole extending therethrough, through which the suction/discharge pipe  28  extends. The inner and outer lower shells  122 ,  126  can be made of a metal plate by molding, and the damping layer  124  can be made of a material that can block vibration and sound. The lower casing  120  is assembled in the following order, the inner lower shell  122 , the damping layer  124  and the outer lower shell  126 . 
     Preferably, the lower casing  120  is made of a multi-layer structure  130  ( FIG. 4 ) (also referred to herein as “double-coalescence metal plate”) in which a metal layer  132 , a damping layer  134  and a metal layer  136  are integrally formed over one another in turn. It is preferred that the damping layers  124  and/or  134  are formed of a viscoelastic polymer. 
     The upper casing  110  may be prepared in a conventional way, i.e., by shaping a single metal layer by molding. Preferably, the upper casing  110  is made in the multi-layer structure, as in the lower casing  120 . Accordingly, the upper casing  110  is constructed of an inner upper shell  112 , an upper damping layer  114  and an outer upper shell  116 . The inner upper shell  112  and the outer upper shell  116  are made of metal, while the upper damping layer  114  is made of vibration blocking material. As in the lower casing  120 , the upper casing  110  is preferably formed by using the double-coalescence metal plate  130 . 
     Referring to  FIGS. 3A through 3C , different embodiments of the connecting structures are shown, the upper casing  110  and the lower casing  120  being connected with each other in the following order: fitting the upper casing  110  into the lower casing  120 , and welding the joint area (“A” portion).  FIG. 3A  shows the adjacent connecting structure of the upper casing  110  and the lower casing  120  in which the outer upper shell  116  of the upper casing is in contact with the inner lower shell  122  of the lower casing  120 .  FIG. 3B  shows the connecting structure between the upper damping layer  114  of the upper casing  110  and the inner lower shell  122  of the lower casing  120 .  FIG. 3C  shows the adjacent connecting structure between the upper damping layer  114  of the upper casing  110  and the lower damping layer  124  of the lower casing  120 . 
     The process of damping the vibration of the compressor body in the hermetic compressor according to the present invention will be described below with reference to the accompanying drawings. 
     By turning on the electric supply to the compressor, the rotor  14  starts rotating. With the rotation of the rotor  14 , the rotary shaft  16 , integrally formed with the rotor  14 , also rotates. As the rotary shaft  16  rotates, the piston  24  starts reciprocating in the cylinder body  22  by action of the eccentric portion  18  and the connecting rod  20  at one end of the rotary shaft  16 . As the piston  24  reciprocates within the cylinder bore  23  in the cylinder body  22 , the valve  26  enters into a repeat reciprocal motion, thus permitting the refrigerant to enter for compression and exit to the refrigerant cycle through the suction/discharge pipe  28 . Accordingly, as the piston  24  moves to the lower dead end, the suction valve  29  opens to permit the low temperature and lower pressure gaseous refrigerant into the bore  23  of cylinder body  22  through the suction pipe (not shown). As the piston  24  moves toward the upper dead end, the suction valve  29  closes so that the drawn refrigerant is compressed. After the refrigerant compression, the discharge valve  27  opens, thereby permitting the compressed refrigerant to be discharged toward the condenser through the discharge pipe  28 . The rotary shaft  16  rotates and the piston  24  keeps moving between the upper and lower dead ends, drawing in and discharging out the refrigerant repeating the cycle. 
     As described above, during the refrigerant suction, compression and discharge of the compressor body  10 , a considerable amount of vibration and noise is produced as the rotor  14  rotates and the rotary motion of the rotor  14  is converted into reciprocal motion of the piston  24  by the action of the eccentric portion  18  and the connecting rod  20 . The supporting member  30  absorbs the vibration and noise produced from the compressor body  10 , thereby reducing the level of vibration and noise. However, the vibration and noise is incompletely damped, and the vibration and noise is transmitted to the inner lower shell  122 . In this case, the vibration and noise is again damped by the damping layer  124  because the vibration and noise is used to deform the viscoelastic polymer that constitutes the damping layer  124 . As the vibration and noise is blocked by the presence of the damping layer  124 , there is little or no vibration or noise transmitted to the outer lower shell  126 . The energy of vibration transmitted from the compressor body  10  to the inner upper shell  112  of the upper casing  110  is also used to deform the upper damping layer  124 , and as a result, vibration is reduced. 
     As described above, with the hermetic compressor casing according to the present invention, the level of vibration and noise from the compressor body  10  to the outside environment is reduced.  FIGS. 5 and 6  show the considerable reduction of vibration and noise in the hermetic compressor according to the present invention. 
       FIGS. 5 and 6  are comparison graphs showing the comparison of amplitude and vibration between the hermetic compressor employing the casing according to the present invention that is made of double-coalescence metal plate having a damping layer of viscoelastic material as against the hermetic compressor employing a conventional casing. The curves  2  in each of  FIGS. 5 and 6  represent the amplitude and vibration of the hermetic compressor using a conventional casing, while curves  1  in each of  FIGS. 5 and 6  represent the amplitude and vibration of the hermetic compressor using the casing according to the present invention. 
     Although the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiments, but various changes and modifications can be made within the spirit and scope of the present invention as defined by the appended claims.