Patent Publication Number: US-2009232672-A1

Title: Refrigerating compressor and refrigerating device using the same

Description:
TECHNICAL FIELD 
     The present invention relates to a refrigerating compressor to be used in a refrigerator, and it also relates to a refrigerating device using the same compressor. 
     BACKGROUND ART 
     A conventional refrigerating compressor including a feed oil pipe dipped in oil is disclosed in Unexamined Japanese Patent Publication No. H11-303740, for example. The conventional compressor is described hereinafter with reference to  FIGS. 5 and 6 . 
       FIG. 5  shows a vertical sectional view of the conventional refrigerating compressor, and  FIG. 6  shows an essential part enlarged from  FIG. 5 . Hermetic container  1  accommodates oil  2  and motor  3 . Compressing unit  4  driven by motor  3  is also accommodated in container  1  under motor  3 . 
     Compressing unit  4  has cylinder block  7  including cylinder  5  and bearing  6 ; and crankshaft  10  including eccentric section  8  and main shaft  9  which is supported by bearing  6 . Eccentric section  8  of crankshaft  10  is connected to piston  11  via connecting rod  12 . Piston  11  is inserted reciprocally in cylinder  5 . 
     Valve plate  14  seals an opening end of cylinder  5 , and discharging valve  13  is provided to valve plate  14  on the other side of cylinder  5 . Valve plate  14  has suction valve  15 . A first end of suction muffler  17  communicates with suction valve  15 , a second end of suction muffler  17  opens into container  1  via sound deadening space  16 . 
     Eccentric section  8  has feed oil pipe  18  at its lower end, and a first end of oil feed pipe  18  is press-fitted to eccentric section  8  and a second end thereof is dipped in oil  2 . Feed oil pipe  18  is formed of a steel pipe, and is bent to form a V-shape including an obtuse angle such that the second end dipped in oil  2  is positioned at the rotating center of main shaft  9 . 
     The operation of the refrigerating compressor having the foregoing structure is described hereinafter. The spin of crankshaft  10  by motor  3  is transmitted to connecting rod  12 , so that piston  11  reciprocates. This reciprocation sucks refrigerant into suction muffler  17 , and intermittently sucks the refrigerant into cylinder  5  via suction valve  15 . The refrigerant flows through an outer cooling circuit (not shown) and is temporarily released into hermetic container  1  before it is sucked into suction muffler  17 . The refrigerant sucked into cylinder  5  is compressed by piston  11 , and pushes discharge valve  13  open, so that the refrigerant is discharged again into the outer cooling circuit. Oil  2  stored in container  1  is drawn through oil feed pipe  18  by centrifugal force of feed oil pipe  18  placed at the lower end of eccentric section  8  and is delivered to respective sliding sections of compressing unit  4 . 
     In the foregoing structure, eccentric section  8  of crankshaft  10  is vibrated by large intermittent loads applied from connection rod  12  when compressing unit  4  compresses the refrigerant, so that eccentric section  8  repeats bending deformation. The vibration of eccentric section  8  travels to feed oil pipe  18 . Then feed oil pipe  18  is vibrated and thus generates resonance sound. 
     In addition, feed oil pipe  18  rotates in oil  2 , thereby agitating oil  2 . Oil  2  collides with structural elements of the compressor in container  1 , and the flow of oil  2  is thus disturbed, so that no neat eddy is formed. In this status, the refrigerant dissolved in oil  2  foams. This foam collides with feed oil pipe  18  following the disturbance of oil  2 , thereby vibrating feed oil pipe  18  and generating the resonance sound. This phenomenon is conspicuous particularly when the refrigerant, e.g. hydrocarbon, dissolved much amount in oil  2  is used. 
     The vibration due to the resonance of feed oil pipe  18  travels to hermetic container  1  via oil  2 , and radiates to the outside of container  1  as noises, so that the refrigerating compressor becomes noisy. 
     DISCLOSURE OF INVENTION 
     The refrigerating compressor of the present invention has a hermetic container accommodating oil; a motor accommodated in the hermetic container; a compressing unit disposed under the motor, accommodated in the container, and driven by the motor; and a vibration insulating wall. The compressing unit includes a crankshaft, a cylinder block, a piston, a connecting rod, and a feed oil pipe. The crankshaft has a main shaft and an eccentric section. The cylinder block has a bearing for supporting the main shaft rotatably, and a cylinder. The piston reciprocates in the cylinder. The connecting rod connects the piston to the eccentric section. The feed oil pipe is fixed to the eccentric section, and one of its ends is dipped into the oil. The vibration insulating wall is disposed inside of the container at the bottom, and surrounds the feed oil pipe with a given space in between. This structure allows isolating the resonance sound traveling from the pipe to the container, so that a refrigerating compressor with low noises is obtainable. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a vertical sectional view of a refrigerating compressor in accordance with an embodiment of the present invention. 
         FIG. 2  shows an essential part of the compressor enlarged from  FIG. 1 . 
         FIG. 3  shows a lateral sectional view of the refrigerating compressor shown in  FIG. 1 . 
         FIG. 4  shows a refrigerating cycle of a refrigerating device employing the refrigerating compressor shown in  FIG. 1 . 
         FIG. 5  shows a vertical sectional view of a conventional refrigerating compressor. 
         FIG. 6  shows an essential part enlarged from the conventional compressor. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     An exemplary embodiment of the present invention is demonstrated hereinafter with reference to the accompanying drawings. This embodiment does not limit the invention. 
       FIGS. 1 ,  2  and  3  show a vertical sectional view, a sectional view illustrating an essential part enlarged, and a lateral sectional view of the refrigerating compressor in accordance with the embodiment of the present invention, respectively. Refrigerating compressor  50  includes hermetic container  101 , motor  106 , compressing unit  107 , and vibration insulating wall  125 . 
     Hermetic container  101  stores oil  102  formed of mineral oil at its bottom, and is filled with refrigerant  103  formed of hydrocarbon such as R600a (isobutane). Hermetic container  101  accommodates motor  106  having stator  104  and rotor  105 , and compressing unit  107  driven by motor  106 . Compressing unit  107  is placed under motor  106 . 
     Next, a structure of compressing unit  107  is described hereinafter. Crankshaft  110  includes main shaft  109 , rigidly inserted into rotor  105  of motor  106 , and eccentric section  108 . Cylinder block  114  includes bearing  111  for supporting main shaft  109  rotatably, and cylinder  113 , into which piston  115  is inserted for forming compressing room  112 . Cylinder block  114  supports stator  104 . Eccentric section  108  of crankshaft  110  is connected to piston  115  by connecting rod  116 . 
     Feed oil pipe  118  (hereinafter referred simply as “pipe  118 ”) attaches to the lower end of eccentric section  108  such that a first end of pipe  118  is press-fitted to the lower end of eccentric section  108  and a second end is dipped in oil  102  and placed on an extension line of the rotation axis of main shaft  109 . Pipe  118  is formed of a steel pipe such as carbon steel pipe for machine construction, and bent at bent section  117  to form a V-shape including an obtuse angle. Feed oil hole  119 , into which pipe  118  is press-fitted, communicates with respective sliding sections of compressing unit  107 . 
     A structure of hermetic container  101  is described hereinafter. Hermetic container  101  includes lower container  120  and upper container  121  both formed by drawing hot-rolled sheet steel, for example, and lower and upper containers  120  and  121  are welded at junction  122  by electric welding. Lower container  120  is equipped with discharge pipe  123  and suction pipe  124  both connected to the refrigerating cycle detailed later and shown in  FIG. 4 . 
     Valve plate  131  seals an opening end of cylinder  113 , and discharge valve  130  is provided to valve plate  131  on the other side of cylinder  113 . Valve plate  131  is equipped with suction valve  132 . A first end of suction muffler  134  communicates with suction valve  132 , and a second end of suction muffler  134  opens into hermetic container  101  via sound deadening space  133 . 
       FIG. 4  shows a refrigerating cycle of a refrigerating device including refrigerating compressor  50 . Refrigerating compressor  50  is coupled to heat exchanger  60  on heat absorption side (hereinafter simply referred to as “heat exchanger  60 ”), namely low pressure side of the refrigerating cycle, by suction pipe  124  shown in  FIG. 3 . Refrigerating compressor  50  is also coupled to heat exchanger  70  on heat radiation side (hereinafter referred simply as “heat exchanger  70 ”), namely high pressure side of the refrigerating cycle, by discharge pipe  123 . Compressed refrigerant  103  is discharged from discharge pipe  123 , and is sent to heat exchanger  70  for radiating heat, then returns to heat exchanger  60  via expansion valve  80  for absorbing heat. The refrigerating device is thus formed. 
     Next, vibration insulating wall  125  disposed in lower container  120  is described hereinafter. Vibration insulating wall  125  is shaped like a cup and is placed inside lower container  120  at the bottom so that it surrounds pipe  118  with a given distance in between. Vibration insulating wall  125  is made of the material such as metal and polybutylene terephthalate resin which is not swelled by refrigerant  103  or oil  102 . 
     Vibration insulating wall  125  is sandwiched by fixing nut  127  and the bottom of lower container  120  with fixing bolt  126 . Fixing bolt  126  extends through the bottom of vibration insulating wall  125  and welded to lower container  120  by electric welding. Fixing nut  127  is screwed on bolt  126 . 
     The operation of the refrigerating compressor having the foregoing structure is demonstrated hereinafter. Motor  106  in operation prompts rotor  105  to rotate crankshaft  110 , thereby reciprocating piston  115  in cylinder  113  via connecting rod  116 . This motion allows refrigerant  103 , flowing from heat exchanger  60  shown in  FIG. 4 , to pass through suction pipe  124  and be released temporarily into hermetic container  101 , then be sucked into suction muffler  134 , and be drawn intermittently into compressing room  112  in cylinder  113  via suction valve  132 . Refrigerant  103  flowing into compressing room  112  is compressed by piston  115  reciprocating in cylinder  113 , then pushes discharge valve  130  open, so that refrigerant  103  is discharged from discharge pipe  123  to heat exchanger  70  shown in  FIG. 4 . 
     Pipe  118  rotates together with crankshaft  110 . The first end of pipe  118  is press-fitted into eccentric section  108  roughly at the center. The second end of pipe  118  is dipped in oil  102  and positioned on the extension line of the rotation axis of main shaft  109 , so that the centrifugal force due to the rotation works on oil  102  in pipe  118 . This centrifugal force works as pumping force which delivers, via feed oil hole  119 , oil  102  inside vibration insulating wall  125  to respective sliding sections of compressing unit  107 . 
     Compression load applied to piston  115  allows applying loads intermittently to eccentric section  108 , which thus repeats bending deformation. This deformation of eccentric section  108  travels as vibration to pipe  118 , thereby vibrating pipe  118 , so that pipe  118  generates resonance. However, in refrigerating compressor  50 , vibration insulating wall  125  cuts off the travel of the resonance of pipe  118  to hermetic container  101 . As a result, the vibration travelling from pipe  118  to lower container  120  is attenuated, and the noise to be radiated from hermetic container  101  to the outside is suppressed to a lower level. 
     Vibration insulating wall  125  is preferably made of vibration damping material such as polybutylene terephthalate resin, so that a greater amount of attenuation is obtainable and the noise radiated to the outside of hermetic container  101  can be suppressed to an excessively low level. 
     It is preferable that communicating hole  128  having a smaller diameter than an inner diameter of pipe  118  is provided at the lower part of vibration insulating wall  125 . This structure allows continuous supply of oil  102  from the outside of vibration insulating wall  125  through communicating hole  128  into the inside of vibration insulating wall  125  even if the surface of oil  102  inside wall  125  lowers. As a result, supply of oil  102  is never cut off to the respective sliding sections of compressing unit  107 . 
     Upper end  129  of vibration insulating wall  125  preferably extends upward and exceeds the surface of oil  102 . This structure allows oil  102  inside vibration insulating wall  125  to communicate with oil  102  in hermetic container  101  only through communicating hole  128 . Hole  128  has a diameter smaller than that of pipe  118  so that no oil shortage occurs inside vibration insulating wall  125 , so that few vibrations travel from pipe  118  to hermetic container  101  via communicating hole  128 . As a result, vibration insulating wall  125  effectively isolates the resonance of pipe  118 . 
     Next, the situation where bubbles of refrigerant  103  collide with pipe  118 , is demonstrated hereinafter. When refrigerating compressor  50  starts operating, the inside of hermetic container  101  is decompressed. As a result, refrigerant  103  dissolved in oil  102  during the halt of refrigerating compressor  50  starts foaming. The bubble of refrigerant  103  generated at this time draws an eddy-like path following the rotation of pipe  118 , and the bubbles are drawn to the tip of pipe  118  together with oil  102 . At this time, when the bubbles is drawn together with oil  102  disturbed around pipe  118  to the tip of pipe  118 , the bubbles collide with the inner and outer walls of pipe  118 , so that pipe  118  is greatly vibrated. 
     Considering the status discussed above, it is preferable that the inner wall of vibration insulating wall  125  shapes like a smooth body of revolution revolving on an extension line of the rotation axis of main shaft  109 . This shape is free from inward protrusions, so that oil  102  inside vibration insulating wall  125  rotates in a conical shape without disturbance following the rotation of pipe  118 . As a result, drawing a smooth circle, the bubbles of refrigerant  103  in oil  102  approach to the tip of pipe  118 , so that collisions between the bubbles and the inside or outside wall of pipe  118  decrease drastically. Oil  102  including the bubbles is thus smoothly drawn into pipe  118 , and the resonance of pipe  118  decreases also drastically. 
     Refrigerant  103  such as hydrocarbon and oil  102  such as mineral oil or alkyl benzene are mutually soluble with each other, so that refrigerant  103  dissolved in oil  102  during the halt of refrigerating compressor  50  abruptly starts foaming when refrigerating compressor  50  starts operating. After this abrupt foaming is finished, refrigerant  103  in oil  102  more or less foams successively during the operation of refrigerating compressor  50 . 
     In this embodiment, refrigerant  103  easy to foam is combined with oil  102 . A noise level of hermetic container  101  due to resonance can be lowered even if the resonance of pipe  118  frequently occurs due to the collision between the bubbles and pipe  118  with this combination. This is because vibration insulating wall  125 , formed of the vibration damping member, efficiently damps the vibration travelling in oil  102 , thereby reducing drastically the vibration transmitted to the outside of vibration insulating wall  125 . As discussed above, even use of pipe  118 , weakening the noise of refrigerating compressor  50  to an excessively low level is allowed. Pipe  118  made of a steel pipe such as a carbon steel pipe for machine construction is just bent at bent section  117  to form a V-shape including an obtuse angle, so that pipe  118  is obtainable at a high productivity. 
     Pipe  118  violently agitates oil  102 , which thus splashes from the oil surface, so that the oil drops scatter. This particular case is described hereinafter. When pipe  118  rotates in oil  102  during the operation of refrigerating compressor  50 , the centrifugal force works on oil drops attached to the outer wall of pipe  118 . This centrifugal force sometimes produces oil drops splashed and separated from the oil surface of oil  102 . The oil drop, in general, splashes along the outer rim of pipe  118  and collides with hermetic container  101  or compressing unit  107 , thereby causing noises. 
     Upper end  129  of vibration insulating wall  125  preferably extends upward and exceeds bent section  117  of pipe  118 . This structure allows the inner face of vibration insulating wall  125  to catch the oil drops splashed by pipe  118 , so that the scatter of oil drops is prevented from colliding with hermetic container  101  or compressing unit  107 . As a result, noises can be prevented. 
     In this embodiment, vibration insulating wall  125  made of resin such as polybutylene terephthalate resin is used; however, vibration damping steel plate or rubber such as nitrile-butadiene rubber can be used instead of the resin, and these materials produce an advantage similar to what is discussed above. Cold-rolled sheet steel, which is inexpensive and highly formable, can be used as the material of vibration insulating wall  125  with an advantage similar to the foregoing one. 
     INDUSTRIAL APPLICABILITY 
     A refrigerating compressor of the present invention is useful for a refrigerating device to be used in a home-use refrigerator which requires quiet operation, and it is applicable to business-use refrigerators to be used in hotels or a medical care industry.
       1  hermetic container     2  oil     3  motor     4  compressing unit     5  cylinder     6  bearing     7  cylinder block     8  eccentric section     9  main shaft     10  crankshaft     11  piston     12  connecting rod     13  discharge valve     14  valve plate     15  suction valve     16  sound deadening space     17  suction muffler     18  feed oil pipe     50  refrigerating compressor     60  heat exchanger on heat absorption side     70  heat exchanger on heat radiation side     80  expansion valve     101  hermetic container     102  oil     103  refrigerant     104  stator     105  rotor     106  motor     107  compressing unit     108  eccentric section     109  main shaft     110  crankshaft     111  bearing     112  compressing room     113  cylinder     114  cylinder block     115  piston     116  connecting rod     117  bent section     118  feed oil pipe     119  feed oil hole     120  lower container     121  upper container     122  junction     123  discharge pipe     124  suction pipe     125  vibration insulating wall     126  fixing bolt     127  fixing nut     128  communicating hole     129  upper end     130  discharge valve     131  valve plate     132  suction valve     133  sound deadening space     134  suction muffler