Refrigeration apparatus

Abstract

An air conditioner ( 10 ) comprised of a refrigeration apparatus includes a main controller ( 60 ), and a sub-controller ( 70 a, 70 b ). A compressor control section of the main controller ( 60 ) adjusts operational capacity of the compressor ( 31 ), and stops the compressor ( 31 ) when capability of the air conditioner ( 10 ) is excessive relative to a load. When a frequency at which the compressor ( 31 ) is started and stopped by the compressor control section is increased, a target superheat degree changing section of the main controller ( 60 ) forcibly increases a target degree of superheat. Then, in air cooling operation, the sub-controller ( 70 a, 70 b ) adjusts the degree of opening of an indoor expansion valve ( 42, 47 ) based on the increased target degree of superheat. In air heating operation, the main controller ( 60 ) adjusts the degree of opening of an outdoor expansion valve ( 34 ) based on the increased target degree of superheat.

1 . A refrigeration apparatus comprising:
 a refrigerant circuit ( 20 ) which includes a compressor ( 31 ), an expansion mechanism ( 34 ,  42 ,  47 ), a heat source-side heat exchanger ( 33 ), and a utilization-side heat exchanger ( 41 ,  46 ) connected thereto, and performs a refrigeration cycle in which high pressure is set higher than critical pressure of a refrigerant; and   a control means ( 80 ) which controls the compressor ( 31 ) and the expansion mechanism ( 34 ,  42 ,  47 ), wherein   the control means ( 80 ) is configured to perform
 capacity control operation of adjusting capacity of the compressor ( 31 ) in such a manner that a physical value representing an operating state of the refrigeration cycle performed by the refrigerant circuit ( 20 ) reaches a target control value, 
 flow rate control operation of adjusting a flow rate of the refrigerant passing through the expansion mechanism ( 34 ,  42 ,  47 ) in such a manner that a degree of superheat of the refrigerant flowing from one of the heat source-side heat exchanger ( 33 ) and the utilization-side heat exchanger ( 41 ,  46 ) which functions as an evaporator to the compressor ( 31 ) reaches a target degree of superheat, and 
 a target superheat degree changing operation of forcibly increasing the target degree of superheat when the compressor ( 13 ) is stopped by the capacity control operation. 
   
     
     
         2 . The refrigeration apparatus comprising:
 a refrigerant circuit ( 20 ) which includes a compressor ( 31 ), an expansion mechanism ( 34 ,  42 ,  47 ), a heat source-side heat exchanger ( 33 ), and a utilization-side heat exchanger ( 41 ,  46 ) connected thereto, and performs a refrigeration cycle in which high pressure is set higher than critical pressure of a refrigerant; and   a control means ( 80 ) which controls the compressor ( 31 ),   the refrigeration apparatus performing at least cooling operation in which the heat source-side heat exchanger ( 33 ) functions as a gas cooler, and the utilization-side heat exchanger ( 41 ,  46 ) functions as an evaporator, wherein   the control means ( 80 ) is configured to perform
 capacity control operation of adjusting capacity of the compressor ( 31 ) in such a manner that a control parameter, which is evaporating temperature of the refrigerant in the utilization-side heat exchanger ( 41 ,  46 ), or low pressure of the refrigeration cycle performed by the refrigerant circuit ( 20 ), reaches a target control value, and 
 target control value changing operation of gradually reducing the target control value after the compressor ( 31 ) is started in such a manner that the target control value reaches a predetermined standard target value after a predetermined period of time from the start of the compressor ( 31 ). 
   
     
     
         3 . The refrigeration apparatus comprising:
 a refrigerant circuit ( 20 ) which includes a compressor ( 31 ), an expansion mechanism ( 34 ,  42 ,  47 ), a heat source-side heat exchanger ( 33 ), and a utilization-side heat exchanger ( 41 ,  46 ) connected thereto, and performs a refrigeration cycle in which high pressure is set higher than critical pressure of a refrigerant; and   a control means ( 80 ) which controls the compressor ( 31 ),   the refrigeration apparatus performing at least heating operation in which the utilization-side heat exchanger ( 41 ,  46 ) functions as a gas cooler, and the heat source-side heat exchanger ( 33 ) functions as an evaporator, wherein   the control means ( 80 ) is configured to perform
 capacity control operation of adjusting capacity of the compressor ( 31 ) in such a manner that a control parameter, which is high pressure of the refrigeration cycle performed by the refrigerant circuit ( 20 ), reaches a target control value, and 
 target control value changing operation of gradually increasing the target control value after the compressor ( 31 ) is started in such a manner that the target control value reaches a predetermined standard target value after a predetermined period of time from the start of the compressor ( 31 ). 
   
     
     
         4 . The refrigeration apparatus comprising:
 a refrigerant circuit ( 20 ) which includes a compressor ( 31 ), an expansion mechanism ( 34 ,  42 ,  47 ), a heat source-side heat exchanger ( 33 ), and a utilization-side heat exchanger ( 41 ,  46 ) connected thereto, and performs a refrigeration cycle in which high pressure is set higher than critical pressure of a refrigerant; and   a control means ( 80 ) which controls the compressor ( 31 ), wherein   the control means ( 80 ) is configured to perform
 capacity control operation of adjusting capacity of the compressor ( 31 ) based on a command value calculated using a physical value representing an operating state of the refrigeration cycle performed by the refrigerant circuit ( 20 ), and a control gain in such a manner that the physical value reaches a target control value, and 
 gain adjustment operation of reducing the control gain as a load of the refrigeration apparatus is reduced.