Refrigeration system

Abstract

In a refrigeration system in which a compressor mechanism including a plurality of compressors, oil separators ( 37 a, 37 b ) are provided at a discharge pipe ( 56 a ) of a first compressor ( 14 a ) and a discharge pipe ( 56 b ) of a second compressor ( 14 b ), respectively. An oil return passageway ( 32 ) for returning refrigerating machine oil from the oil separators ( 37 a, 37 b ) to a compressor mechanism ( 40 ) is configured to combine streams of refrigerating machine oil separated in the oil separators ( 37 a, 37 b ) and distribute the combined refrigerating machine oil to the first compressor ( 14 a ) and the second compressor ( 14 b ).

1 . A refrigeration system including a refrigerant circuit ( 4 ) which is configured to perform a refrigeration cycle and provided with a compressor mechanism ( 40 ) including a first compressor ( 14   a ) and a second compressor ( 14   b ) whose discharge sides are connected to each other, the refrigeration system comprising:
 oil separators ( 37   a,    37   b ) provided at a discharge pipe ( 56   a ) of the first compressor ( 14   a ) and a discharge pipe ( 56   b ) of the second compressor ( 14   b ), respectively; and   an oil return passageway ( 32 ) configured to combine streams of refrigerating machine oil separated in the oil separators ( 37   a,    37   b ) and distribute the combined refrigerating machine oil to the first compressor ( 14   a ) and the second compressor ( 14   b ).   
     
     
         2 . The refrigeration system of  claim 1 , further comprising an injection passageway ( 30 ) configured to inject a refrigerant into the first compressor ( 14   a ) and the second compressor ( 14   b ), wherein
 the oil return passageway ( 32 ) includes a junction passageway ( 48 ) in which refrigerating machine oil from the oil separators ( 37   a,    37   b ) flows, and   the junction passageway ( 48 ) is connected to a portion of the injection passageway ( 30 ) located upstream of a branch point to the first compressor ( 14   a ) and the second compressor ( 14   b ).   
     
     
         3 . The refrigeration system of  claim 2 , wherein the compressor mechanism ( 40 ) is configured to always operate the first compressor ( 14   a ) and adjust an operation capacity of the compressor mechanism ( 40 ) by switching the second compressor ( 14   b ) between operation and nonoperation,
 the injection passageway ( 30 ) includes a first branch injection passageway ( 42   a ) branching to the first compressor ( 14   a ) and a second branch injection passageway ( 42   b ) branching to the second compressor ( 14   b ), and   only the second branch injection passageway ( 42   b ) has an oil non-return valve (SV 1 ) which is freely opened and closed and prevents refrigerating machine oil from returning to the compressor ( 14   b ) to which the branch injection passageway ( 42   b ) is connected while the compressor ( 14   b ) stops.   
     
     
         4 . The refrigeration system of  claim 1  or  2 , wherein the compressor mechanism ( 40 ) is configured to always operate the first compressor ( 14   a ) and adjust an operation capacity of the compressor mechanism ( 40 ) by switching the second compressor ( 14   b ) between operation and nonoperation,
 the oil return passageway ( 32 ) includes a first pre-junction passageway ( 47   a ) connected to the oil separator ( 37   a ) at the discharge pipe ( 56   a ) of the first compressor ( 14   a ) and a second pre-junction passageway ( 47   b ) connected to the oil separator ( 37   b ) at the discharge pipe ( 56   b ) of the second compressor ( 14   b ), and 
 only the second pre-junction passageway ( 47   b ) has a check valve (CV 4 ) for preventing refrigerating machine oil from returning to the oil separator ( 37   b ). 
 
     
     
         5 . The refrigeration system of  claim 1 , wherein in the second compressor ( 14   b ), a discharge space ( 100 ) filled with a refrigerant compressed in a fluid machine ( 82 ) configured to compress a fluid in a compression chamber ( 73   a,    73   b ) is formed in a casing ( 70 ) housing the fluid machine ( 82 ),
 a refrigerant-inflow stop valve (CV 2 ) is provided at a portion of the discharge pipe ( 56   b ) of the second compressor ( 14   b ) located downstream of the oil separator ( 37   b ), and stops a flow of a refrigerant into the second compressor ( 14   b ) in a nonoperation state, and   when the second compressor ( 14   b ) stops while the first compressor ( 14   a ) operates, the first compressor ( 14   a ) sucks a refrigerant in the discharge space ( 100 ) in the second compressor ( 14   b ) through the oil return passageway ( 32 ).   
     
     
         6 . The refrigeration system of  claim 1 , wherein
 an outlet side of the oil return passageway ( 32 ) communicates with compression chambers ( 73 ) with intermediate pressures of the respective compressors ( 14   a,    14   b ).   
     
     
         7 . The refrigeration system of  claim 1 , wherein at least one of the first compressor ( 14   a ) and the second compressor ( 14   b ) is a compressor having a variable operation capacity.