Refrigerating apparatus

Abstract

A refrigerating apparatus in which a two-stage compression refrigeration cycle is performed includes a refrigerant circuit and a volume ratio changing unit. The refrigerant circuit is connected to a compressor having a plurality of compression mechanisms mechanically connected together with a single drive shaft. The compression mechanisms include four cylinder chambers. The volume ratio changing unit is configured to change a ratio of a suction volume of a low-pressure compression mechanism to a suction volume of a high-pressure compression mechanism.

1 . A refrigerating apparatus in which a two-stage compression refrigeration cycle is performed, the refrigerating apparatus comprising:
 a refrigerant circuit connected to a compressor having a plurality of compression mechanisms mechanically connected together with a single drive shaft, the compression mechanisms including four cylinder chambers; and   a volume ratio changing unit configured to change a ratio of a suction volume of a low-pressure compression mechanism to a suction volume of a high-pressure compression mechanism.   
     
     
         2 . The refrigerating apparatus of  claim 1 , wherein
 the volume ratio changing unit is configured to change the ratio of the suction volume of the low-pressure compression mechanism to the suction volume of the high-pressure compression mechanism by changing a combination of the four cylinder chambers.   
     
     
         3 . The refrigerating apparatus of  claim 1 , wherein
 the plurality of compression mechanisms include a first compression mechanism and a second compression mechanism, with each of the first and second compression mechanisms including two cylinder chambers, and   each of the first and second compression mechanisms includes a cylinder with a circular cylinder space and a circular eccentric piston eccentrically movable in the cylinder to form an inner cylinder chamber on an inner circumferential side of the circular eccentric piston in the cylinder and and an outer cylinder chamber on an outer circumferential side of the circular eccentric piston.   
     
     
         4 . The refrigerating apparatus of  claim 3 , wherein
 the four cylinder chambers set to at least two suction volume levels.   
     
     
         5 . The refrigerating apparatus of  claim 3 , wherein
 suction volumes of the four cylinder chambers are different from each other.   
     
     
         6 . The refrigerating apparatus of  claim 3 , wherein,
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the inner cylinder chamber and the outer cylinder chamber of the second compression mechanism are connected together in parallel, and 
 a state in which the inner cylinder chamber and the outer cylinder chamber of the second compression mechanism are connected together in series 
   
       when the first compression mechanism is at a low-pressure stage and the second compression mechanism is at a high-pressure stage. 
     
     
         7 . The refrigerating apparatus of  claim 3 , wherein
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which both of the cylinder chambers of the first compression mechanism are used as the low-pressure compression mechanism, and both of the cylinder chambers of the second compression mechanism are used as the high-pressure compression mechanism, and 
 a state in which both of the cylinder chambers of the first compression mechanism and one of the cylinder chambers of the second compression mechanism are used as the low-pressure compression mechanism, and the other cylinder chamber of the second compression mechanism is used as the high-pressure compression mechanism. 
   
     
     
         8 . The refrigerating apparatus of  claim 3 , wherein
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which both of the cylinder chambers of the first compression mechanism are used as the low-pressure compression mechanism, and both of the cylinder chambers of the second compression mechanism are used as the high-pressure compression mechanism, and 
 a state in which one of the cylinder chambers of the first compression mechanism and one of the cylinder chambers of the second compression mechanism are used as the low-pressure compression mechanism, and the other cylinder chamber of the first compression mechanism and the other cylinder chamber of the second compression mechanism are used as the high-pressure compression mechanism. 
   
     
     
         9 . The refrigerating apparatus of  claim 3 , wherein,
 the volume ratio changing unit includes a switching mechanism which is switchable between
 a state in which refrigerant is compressed in both of the cylinder chambers of the second compression mechanism to provide a difference between a suction pressure and a discharge pressure, and 
 a state in which refrigerant is compressed in one of the cylinder chambers of the second compression mechanism to provide the difference between the suction pressure and the discharge pressure, and substantially identical suction and discharge pressures in the other cylinder chamber allow uncompressed refrigerant to pass through the other cylinder chamber 
   
       when the first compression mechanism is at a low-pressure stage and the second compression mechanism is at a high-pressure stage. 
     
     
         10 . The refrigerating apparatus of  claim 3 , wherein,
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which refrigerant is compressed in both of the cylinder chambers of the first compression mechanism to provide a difference between a suction pressure and a discharge pressure, and 
 a state in which refrigerant is compressed in one of the cylinder chambers of the first compression mechanism to provide the difference between the suction pressure and the discharge pressure, and substantially identical suction and discharge pressures in the other cylinder chamber allow uncompressed refrigerant to pass through the other cylinder chamber 
   
       when the first compression mechanism is at a low-pressure stage and the second compression mechanism is at a high-pressure stage. 
     
     
         11 . The refrigerating apparatus of  claim 1 , wherein
 the switching mechanism includes a switching valve configured to switch a flow path of low-pressure, intermediate-pressure, or high-pressure refrigerant into each of the compression mechanisms.   
     
     
         12 . The refrigerating apparatus of  claim 1 , wherein
 the volume ratio changing unit is further configured to change the ratio of the suction volume of the low-pressure compression mechanism to the suction volume of the high-pressure compression mechanism depending on a change in operational conditions.   
     
     
         13 . The refrigerating apparatus of  claim 1 , wherein
 the plurality of compression mechanisms include a first compression mechanism, a second compression mechanism, a third compression mechanism, and a fourth compression mechanism, with each of the first, second, third and fourth compression mechanisms including a single cylinder chamber, and   each of the first, second, third and fourth compression mechanisms includes a cylinder with a circular cylinder space and an eccentric piston eccentrically movable in the cylinder space.   
     
     
         14 . The refrigerating apparatus of  claim 13 , wherein
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the first compression mechanism and the second compression mechanism are used as the low-pressure compression mechanism, and the third compression mechanism and the fourth compression mechanism are used as the high-pressure compression mechanism, and 
 a state in which the first compression mechanism, the second compression mechanism, and the third compression mechanism are used as the low-pressure compression mechanism, and the fourth compression mechanism is used as the high-pressure compression mechanism. 
   
     
     
         15 . The refrigerating apparatus of  claim 13 , wherein
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the first compression mechanism and the third compression mechanism are used as the low-pressure compression mechanism, and the second compression mechanism and the fourth compression mechanism are used as the high-pressure compression mechanism, and 
 a state in which the first compression mechanism is used as the low-pressure compression mechanism, and the second compression mechanism, the third compression mechanism, and the fourth compression mechanism are used as the high-pressure compression mechanism. 
   
     
     
         16 . The refrigerating apparatus of  claim 13 , wherein
 a cylinder volume of at least one of the compression mechanisms is different from cylinder volumes of the other compression mechanisms, and   the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the first compression mechanism and the second compression mechanism are used as the low-pressure compression mechanism, and the third compression mechanism and the fourth compression mechanism are used as the high-pressure compression mechanism, and 
 a state in which the first compression mechanism and the third compression mechanism are used as the low-pressure compression mechanism, and the second compression mechanism and the fourth compression mechanism are used as the high-pressure compression mechanism. 
   
     
     
         17 . The refrigerating apparatus of  claim 13 , wherein,
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which refrigerant is compressed in both of the third compression mechanism and the fourth compression mechanism to provide a difference between a suction pressure and a discharge pressure, and 
 a state in which refrigerant is compressed in one of the third compression mechanism and the fourth compression mechanism to provide the difference between the suction pressure and the discharge pressure, and substantially identical suction and discharge pressures in the other compression mechanism allow uncompressed refrigerant to pass through the other compression mechanism 
   
       when the first compression mechanism and the second compression mechanism are at a low-pressure stage, and the third compression mechanism and the fourth compression mechanism are at a high-pressure stage. 
     
     
         18 . The refrigerating apparatus of  claim 13 , wherein
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which, when the first compression mechanism and the second compression mechanism are at a low-pressure stage, and the third compression mechanism and the fourth compression mechanism are at a high-pressure stage, refrigerant is compressed in both of the low-pressure and high-pressure compression mechanisms to provide a difference between a suction pressure and a discharge pressure, and 
 a state in which, when the first compression mechanism is at the low-pressure stage, and the second compression mechanism, the third compression mechanism, and the fourth compression mechanism are at the high-pressure stage, refrigerant is compressed in the low-pressure compression mechanism to provide the difference between the suction pressure and the discharge pressure, and substantially identical suction and discharge pressures in one of the second compression mechanism, the third compression mechanism, or the fourth compression mechanism at the high-pressure stage allow uncompressed refrigerant to pass through the one of the second compression mechanism, the third compression mechanism, or the fourth compression mechanism. 
   
     
     
         19 . The refrigerating apparatus of  claim 13 , wherein,
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the first compression mechanism and the second compression mechanism at a low-pressure stage are connected together in parallel, and 
 a state in which the first compression mechanism and the second compression mechanism at the low-pressure stage are connected together in series 
   
       when the first compression mechanism and the second compression mechanism are at the low-pressure stage, and the third compression mechanism and the fourth compression mechanism are at a high-pressure stage. 
     
     
         20 . The refrigerating apparatus of  claim 13 , wherein,
 the volume ratio changing unit includes a switching mechanism switchable between
 a state in which the third compression mechanism and the fourth compression mechanism at a high-pressure stage are connected together in parallel, and 
 a state in which the third compression mechanism and the fourth compression mechanism at the high-pressure stage are connected together in series 
   
       when the first compression mechanism and the second compression mechanism are at a low-pressure stage and the third compression mechanism and the fourth compression mechanism are at the high-pressure stage. 
     
     
         21 . The refrigerating apparatus of  claim 13 , wherein
 the switching mechanism includes a switching valve configured to switch a flow path of low-pressure, intermediate-pressure, or high-pressure refrigerant into each of the first, second, third and fourth compression mechanisms.   
     
     
         22 . The refrigerating apparatus of  claim 13 , wherein
 the volume ratio changing unit is further configured to change the ratio of the suction volume of the low-pressure compression mechanism to the suction volume of the high-pressure compression mechanism depending on a change in operational conditions.   
     
     
         23 . The refrigerating apparatus of  claim 1 , wherein
 refrigerant is carbon dioxide.