Abstract:
A hermetic compressor may include a crankshaft having an input shaft rotatably supported on the cast-iron block along the crankshaft axis and connected to the electric motor rotary output, and an eccentric crankpin orbitally rotating about the axis as the crankshaft is rotated. A pair of opposed pistons may lie on the common plane. Each piston may be pivotably connected to one of the connecting rod piston ends to drive the pistons in an oscillatory manner within the cylinders as the crankshaft rotates. The piston and cylinder pairs may cause fluid to be pumped from the inlet port to the outlet port as the piston oscillates varying the volume of the enclosed space bound by the piston and the cylinder pairs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. application Ser. No. 13/143,869 filed on Sep. 28, 2011, which is the U.S. national phase of PCT Appln. No. PCT/BR2010/000008 filed Jan. 8, 2010 which claims priority to Brazilian application PI 0903956-2 filed Jan. 9, 2009, the disclosures of which are incorporated in their entirety by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The embodiments described herein relate to an apparatus and method for converting rotational motion into linear motion and evacuating non-compressible gases of a compressor. 
       BACKGROUND 
       [0003]    A general hermetic compressor includes a motor portion and compressor portion sealed in a hermetic container. A compressor may be classified as reciprocating, rotary, or any other type where a refrigerant is compressed. In general, a hermetic compressor has a crank shaft coupled to a rotor of the motor part that transfers power to reciprocating pistons. The reciprocating pistons compress the compressible gas within a cylinder. Reciprocating pistons may be arranged in offset horizontal planes that cause unwanted forces on the crankpin and crankshaft. In order to compensate for the unwanted forces, larger crankshaft bearings may be required. 
         [0004]    A lower part of the hermetic container may be filled with oil or a condensed fluid. An oil path is formed in an axial direction of the crank shaft, and an oil feeder is installed at a lower end of the oil path so as to be immersed in oil. As the crank shaft rotates, oil is pumped along the oil path to be fed, supplying the required components with lubrication. The hermetic container may be filled at the factory to properly seal the container. A factory fill may require additional transportation and installation costs. 
       SUMMARY 
       [0005]    A hermetic compressor may include a hermetic shell having a shell and a base which collectively define an enclosed cavity. The hermetic shell may define a discharge port and a suction port. The hermitic compressor may include an electric motor having a stator disposed within the enclosed cavity on the base. The motor may have a rotary output. The compressor may be made of a cast-iron block and include a head assembly. The cast-iron block and head assembly may define a crankshaft axis. The cast-iron block may include a pair of directly opposed cylinders oriented perpendicular to the crankshaft axis, each having an inlet and an outlet port. 
         [0006]    The compressor may include a crankshaft having an input shaft rotatably supported on the cast-iron block along the crankshaft axis and connected to the electric motor rotary output, and an eccentric crankpin orbitally rotating about the axis as the crankshaft is rotated. A pair of opposed pistons may lie on the common plane. Each piston may be pivotably connected to one of the connecting rod piston ends to drive the pistons in an oscillatory manner within the cylinders as the crankshaft rotates. The piston and cylinder pairs may cause fluid to be pumped from the inlet port to the outlet port as the piston oscillates varying the volume of the enclosed space bound by the piston and the cylinder pairs. 
         [0007]    A pair of connecting rods may have a crankshaft end with a bearing opening surrounding the eccentric crankpin, a spaced apart piston end and a rod portion there between. The connecting rods may generally lie in a common plane perpendicular to the input shaft axis with each of the first ends axially offset from one another in a dogleg manner lying on opposite side of the common plane to surround the crankpin. 
         [0008]    The connecting rod assembly may include a friction reduction element disposed between the connecting rod crankshaft ends and a plurality of spring feet mounted on the hermetic shell base in spaced apart relation for supporting the compressor on a support surface. 
         [0009]    A pipe may connect the outlet port of a first cylinder to the inlet port of the other second cylinder in a serial fashion with the first cylinder inlet port coupled to the hermetic shell and the second cylinder outlet port discharging to the discharge port exiting the hermetic shell. In at least one other embodiment, a pair of outlet pipes connect the pair of outlet ports to the discharge port exiting the hermetic shell. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an isometric external view of the compressor used for refrigeration; 
           [0011]      FIG. 2  is a sectional view of a dual cylinder hermetic refrigerant compressor without the hermetic compressor; 
           [0012]      FIG. 3  is a top view of the compressor having a crankshaft and eccentric crankpin; 
           [0013]      FIG. 4  is an isometric view of the compressor having serial discharge; 
           [0014]      FIG. 5  is a top view of the compressor having serial discharge; 
           [0015]      FIG. 6  is a view of the compressor having parallel discharge; 
           [0016]      FIG. 7  is a view of the compressor having spring feet; 
           [0017]      FIG. 8  is a side vertical view of the eccentric and the two bearings; and 
           [0018]      FIG. 9  is a top sectional view of the eccentric and the two bearings. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring to  FIG. 1 , a hermetically sealed compressor includes a hermetic shell  10  including a refill port  28 , discharge port  24 , suction port  22 , and vent port  26 . The hermetic shell  10  has a base  12 , a body  14 , and a top  16 . The hermetic shell  10  contains an oil that fills the base  12  to a level near the seam  13  of the base  12  and body  14 . The hermetic shell  10  has a vent port  26  disposed near the maximum level of the oil to release undesired, uncompressible accumulated gases. 
         [0020]    The preferred embodiment improves on previous methods to evacuate trapped gases that are undesirable. Prior to the preferred embodiment, these trapped gases were evacuated at the site of manufacture by vacuum suction. The preferred embodiment includes a vent port  26  to release trapped air at the installation site. The vent port  26  is disposed above the seam  13  to prevent oil leakage during gas evacuation. 
         [0021]    The vent port  26  provides an effective way to remove trapped gases that are undesirable at the installation site. The method for removing undesirable gases primarily uses the vent port  26  and the refill port  28 . Initially, the vent port  26  is closed. Trapped moisture is then removed from the system by drawing a vacuum on the refill port  28 . The hermetic shell  10  is then pressurized using the refill port  28  and refrigerant or inert gas. The internal pressure of the hermetic shell may be raised to any level sufficient to promote the release of undesirable gases. Typically, the hermetic shell  10  pressure is raised more than one quarter of the normal working pressure, but less than the full normal working pressure of the compressor. 
         [0022]    The heavier air is then allowed to settle to the bottom of the hermetic shell, but above the level of the resting oil, which is generally located at the seam  13 . The opening of the vent port  26  then releases undesirable gases from the hermetic shell, which leaves only oil and refrigerant gas retained in the shell. 
         [0023]    An important requirement prior to the use of the hermetic compressor system is to ensure the proper amount of refrigerant is present in the system prior to use. Verification of adequate refrigerant may be performed numerous ways, but the following are example methods used to verify adequate refrigerant in the system. 
         [0024]    The preferred method to ensure the compressor is adequately filled with refrigerant is to measure the weight and volume of the amount of air removed from the system through the vent port  26 . This method is well known to those skilled in the art. The installer would then add refrigerant as necessary. 
         [0025]    The second method to ensure the proper amount of refrigerant is to measure the internal pressure of the hermetic shell  10  and adjust the amount of refrigerant as necessary. This method is well known to those skilled in the art. The new process for high-efficiency cooling, described as putting gas in the sealed refrigeration systems free from any contamination, caters to all types of gas (e.g. R134 or R600). 
         [0026]    Now referring to  FIGS. 2 and 3 , the motor-compressor  100  has a cast-iron block  103  mounted within the hermetic shell. The motor-compressor  100  has a motor having a stator  102  and end windings  104 . The motor-compressor  100  may be mounted on spring feet  101  to lift the stator  102  of the motor from the base  12  of the hermetic shell  10 . The motor-compressor  100  may have a stator  102  including end turns or end windings  104  to generate a magnetic field, which generate torque on a rotor (not shown). The rotor may be attached to the crankshaft  106 . The crankshaft may be attached to a crankpin  108 . The crankshaft  106  and crankpin  108  may be a unitary piece. The crankshaft  106  may extend concentrically from the center axis of the stator  102  and motor-compressor  100 . The crankshaft  106  has an eccentric crankpin  108  that orbits about the crankshaft  106 . L-shaped connecting rods  110 ,  112  are disposed on the eccentric crankpin  108 . The L-shaped connecting rods  110 ,  112  have a dogleg profile. The motor-compressor has a set of compression chamber heads  114 ,  116 . Each of connecting rods  110 ,  112  include a bearing at the crankpin end or crankpin end portion  118 ,  120  to provide free rotation about the crankpin  108 . Each of the connecting rods  110 ,  112  include a detachable piston end or piston end portion  122 ,  124  that connects to respective pistons  126 ,  128  (piston  128  not shown). 
         [0027]    Now referring to  FIGS. 4 and 5 , an exemplary embodiment of serial discharge is shown. The first cylinder  150  has a first inlet port  152  that receives suction from the volume inside the hermetic shell or the suction port  22 . The first cylinder  150  has a first outlet port  154  that is routed via piping  170  to the second inlet port  162  of the second cylinder  160 . The second outlet port  164  of the second cylinder  160  is routed near the chamber head  116  and is further routed via piping  172  to the compressor discharge port  24  as shown in  FIG. 1 . This provides increased compression and reduced volume of the refrigerant gas. 
         [0028]    Now referring to  FIG. 6 , in at least one other embodiment a parallel discharge configuration  200  is shown. A pair of outlet pipes  270 ,  272  connect the pair of outlet ports (as shown in  FIG. 5 ) of the cylinders to the discharge port exiting the hermetic shell. The first and second cylinders have respective outlet pipes  270 ,  272 . The discharges are fed to a common manifold  274 , which leads to the discharge port  24 . The compressor has similar features to the series configuration of  FIGS. 4 and 5 . As shown, the compressor has an suction port  22 , vent port  26 , and refill port  28 . The hermetic shell has a base  12 , seam  13 , and body  14 . Each compression chamber head  114 ,  116  contains a cylinder (not shown). The compressor has an eccentric crankpin  108  that is free-standing on one end. 
         [0029]    Now referring to  FIG. 7 , the compressor is shown being situated on spring feet  101 , which are attached and support the stator  102 . The spring feet  101  separate the base  12  and the stator  102 . The spring feet  101  are fitted onto brackets welded to the inner wall of the airtight body. The compressor may include four spring feet  101  that are mounted to form a rectangle. The compressor has separate mounting feet  20  for mounting and stabilization. 
         [0030]    Now referring to  FIGS. 8 and 9 , the L-shaped connecting rod  110  defines a hole  119  on the crankpin end  118  of the connecting rod  110 . The hole  119  may be used to connect the crankpin end  118  and piston end  122 . The crankpin end  118  of the connecting rod  110  is rotationally attached to the crankpin  108  with a bearing sized to receive the crankpin  108 . The crankpin end  118  can then orbit about the crankshaft  106 , which has a crankshaft axis  107 , along with the crankpin  108 . The orbiting motion of the crankpin end  118  causes the attached piston end  122  to reciprocate. The reciprocating motion of the piston end  122  causes the piston  126  to similarly reciprocate. The reciprocating motion of the piston  126  compresses the compressible gas of the cylinder. 
         [0031]    The L-shaped connecting rod  110  as described above has a symmetric companion L-shaped connecting rod  112 . The companion L-shaped connecting rod  112  defines a hole  123  on crankpin end  120  of the connecting rod  112 . The hole  123  may be used for a pin to connect the crankpin end  120  and piston end  124 . The crankpin end  120  of the connecting rod  112  is rotationally attached to the crankpin  108  with a bearing sized to receive the crankpin  108 . The crankpin end  120  can then orbit about the crankshaft  106  along with the crankpin  108 . The orbiting motion of the crankpin end  120  causes the attached piston end  124  to reciprocate. The reciprocating motion of the piston end  124  causes the piston  128  to similarly reciprocate. The reciprocating motion of the piston  126  compresses the compressible gas of the cylinder. 
         [0032]    The companion L-shaped connecting rod  112  is flipped about a horizontal plane  111 , which is perpendicular to the eccentric axis or crankpin axis  109 , such that the piston ends  122 ,  124  of both connecting rods  110 ,  112  are aligned along a common horizontal plane  111 . The piston end  124  of the companion L-shaped connecting rod  112  is oriented in the opposite direction of the piston end  122  of the L-shaped connecting rod  110 . 
         [0033]    The orientation of the companion L-shaped connecting rod  112  to the L-shaped connecting rod  110  is one of the novel aspects of the embodiment because the piston ends  122 ,  124  of the connecting rods  110 ,  112  operate on the same horizontal plane  111 . This provides enhanced symmetry for the compressor because each of the pistons  126 ,  128  are disposed on the same plane and create opposing forces. This configuration allows reciprocating movement of the pistons  126 ,  128  in the same plane without undesirable stresses. 
         [0034]    Conflicting rotation of the connecting rods  110 ,  112  may cause unwanted friction and restricted movement. A thin washer  130  may be disposed between the L-shaped connecting rods  110 ,  112  may have a thickness between 0.1 mm and 0.3 mm. The washer may relieve mechanical friction, which tends to create counter force to the rotation of the bearing with respect to each other. 
         [0035]    The connecting rods  110 ,  112  form a tear shape truncated toward the piston ends  122 ,  124 . Each of the connecting rods  110 ,  112  define a bearing opening  125 ,  127  on respective connecting rod crankpin ends  118 ,  120 . The connecting rod crankpin ends  118 ,  120  also define a cleft for receiving the piston ends  122 ,  124  of the connecting rods  110 ,  112 . The pistons  126 ,  128  are connected on the distal end of the connecting rod piston ends  122 ,  124 . The compressor pistons  126 ,  128  reciprocate within the cylinders (not shown).