Refrigeration apparatus

Abstract

A refrigeration apparatus includes: a usage-side expansion valve whose opening degree is changed in response to a change in a flow rate or a pressure of a refrigerant on the upstream side; a first expansion valve; and a controller. The controller exerts, in an oil recovery operation, an oil recovery first control on the first expansion valve to attain a first opening degree (an opening degree of increasing an opening degree of the usage-side expansion valve in relation to a reduction in the flow rate or the pressure of the refrigerant passing through the first expansion valve), to reduce the flow rate or the pressure of the refrigerant passing through the first expansion valve. The controller exerts an oil recovery second control following the oil recovery first control on the first expansion valve to attain a second opening degree (an opening degree that allows a liquid refrigerant to flow into a usage-side heat exchanger before the opening degree of the usage-side expansion valve is reduced in relation to an increase in the flow rate or the pressure of the refrigerant passing through the first expansion valve), to increase the flow rate or the pressure of the refrigerant passing through the first expansion valve.

1 . A refrigeration apparatus configured to carry out a refrigeration cycle through a refrigerant circuit including: a heat source unit including a compressor configured to compress a refrigerant and a heat-source-side heat exchanger functioning as a condenser for the refrigerant; and a service unit including a usage-side heat exchanger functioning as an evaporator for the refrigerant, the refrigeration apparatus comprising:
 a mechanical expansion valve disposed on a refrigerant flow upstream side relative to the usage-side heat exchanger and configured to decompress a refrigerant passing through the mechanical expansion valve in accordance with an opening degree of the mechanical expansion valve;   an electric valve disposed on the refrigerant flow upstream side relative to the mechanical expansion valve and configured to adjust a flow rate or a pressure of a refrigerant passing through the electric valve in accordance with an opening degree of the electric valve; and   a controller configured to control an operation of a plurality of actuators, wherein   the mechanical expansion valve has an opening degree changed in response to an increase and a reduction in a flow rate or a pressure of a refrigerant flowing upstream to the mechanical expansion valve,   the controller executes an oil recovery operation including a first control and a second control for recovering a refrigerating machine oil built up in the service unit to the compressor at a predetermined timing,   by the first control, the electric valve has an opening degree set to a predetermined first opening degree to reduce the flow rate or the pressure of the refrigerant passing through the electric valve,   by the second control, after the first control, the electric valve has an opening degree set to a second opening degree to increase the flow rate or the pressure of the refrigerant passing through the electric valve,   the first opening degree is an opening degree that causes the opening degree of the mechanical expansion valve to increase in relation to a reduction in the flow rate or the pressure of the refrigerant passing through the electric valve, and   the second opening degree is an opening degree that allows, before the opening degree of the mechanical expansion valve is reduced in relation to an increase in the flow rate or the pressure of the refrigerant passing through the electric valve, a liquid refrigerant to flow into the usage-side heat exchanger.   
     
     
         2 . The refrigeration apparatus according to  claim 1 , wherein the controller executes the first control, and executes the second control after a lapse of a predetermined time from execution of the first control. 
     
     
         3 . The refrigeration apparatus according to  claim 1 , wherein the mechanical expansion valve includes a feeler bulb disposed on a refrigerant flow downstream side relative to the usage-side heat exchanger, and has an opening degree changed in response to a detected temperature by the feeler bulb. 
     
     
         4 . The refrigeration apparatus according to  claim 1 , wherein the electric valve is disposed in the heat source unit. 
     
     
         5 . The refrigeration apparatus according to  claim 1 , wherein the controller is disposed at the heat source unit and not electrically connected to any element disposed at the service unit. 
     
     
         6 . The refrigeration apparatus according to  claim 1 , wherein the refrigerant circuit includes a plurality of the service units. 
     
     
         7 . The refrigeration apparatus according to  claim 2 , wherein the mechanical expansion valve includes a feeler bulb disposed on a refrigerant flow downstream side relative to the usage-side heat exchanger, and has an opening degree changed in response to a detected temperature by the feeler bulb. 
     
     
         8 . The refrigeration apparatus according to  claim 2 , wherein the electric valve is disposed in the heat source unit. 
     
     
         9 . The refrigeration apparatus according to  claim 3 , wherein the electric valve is disposed in the heat source unit. 
     
     
         10 . The refrigeration apparatus according to  claim 2 , wherein the controller is disposed at the heat source unit and not electrically connected to any element disposed at the service unit. 
     
     
         11 . The refrigeration apparatus according to  claim 3 , wherein the controller is disposed at the heat source unit and not electrically connected to any element disposed at the service unit. 
     
     
         12 . The refrigeration apparatus according to  claim 4 , wherein the controller is disposed at the heat source unit and not electrically connected to any element disposed at the service unit. 
     
     
         13 . The refrigeration apparatus according to  claim 2 , wherein the refrigerant circuit includes a plurality of the service units. 
     
     
         14 . The refrigeration apparatus according to  claim 3 , wherein the refrigerant circuit includes a plurality of the service units. 
     
     
         15 . The refrigeration apparatus according to  claim 4 , wherein the refrigerant circuit includes a plurality of the service units. 
     
     
         16 . The refrigeration apparatus according to  claim 5 , wherein the refrigerant circuit includes a plurality of the service units.