Refrigeration cycle device

A refrigeration cycle device comprising:

• a main refrigerant circuit having
• a main compressor configured to compress a main refrigerant,
• a main heat-source-side heat exchanger configured to function as a radiator or an evaporator of the main refrigerant,
• a main usage-side heat exchanger configured to function as an evaporator or a radiator of the main refrigerant,
• a sub-usage-side heat exchanger configured to function as a cooler or a heater of the main refrigerant that flows between the main heat-source-side heat exchanger and the main usage-side heat exchanger, and
• a main flow-path switching valve configured to switch between a main cooling operation state, in which the main refrigerant is caused to circulate so that the main usage-side heat exchanger functions as the evaporator of the main refrigerant, and a main heating operation state, in which the main refrigerant is caused to circulate so that the main usage-side heat exchanger functions as the radiator of the main refrigerant;
• and
• a sub-refrigerant circuit having
• a sub-compressor configured to compress a sub-refrigerant,
• a sub-heat-source-side heat exchanger configured to function as a radiator or an evaporator of the sub-refrigerant,
• the sub-usage-side heat exchanger configured to function as an evaporator of the sub-refrigerant and to cool the main refrigerant that flows between the main heat-source-side heat exchanger and the main usage-side heat exchanger, or configured to function as a radiator of the sub-refrigerant and to heat the main refrigerant that flows between the main usage-side heat exchanger and the main heat-source-side heat exchanger, and
• a sub-flow-path switching valve configured to switch between a sub-cooling operation state, in which the sub-refrigerant is caused to circulate so that the sub-usage-side heat exchanger functions as the evaporator of the sub-refrigerant, and a sub-heating operation state, in which the sub-refrigerant is caused to circulate so that the sub-usage-side heat exchanger functions as the radiator of the sub-refrigerant,
• wherein
• the main refrigerant circuit further has
• an upstream-side main expansion valve,
• a main usage side expansion valve provided together with the main usage side heat exchanger at a use unit, and
• a first downstream side main expansion valve,
• wherein the refrigeration cycle device further has a controller configured to control the operation of the refrigeration cycle device,
• wherein the controller is configured to
• control the main flow-path switching valve to switch between the main cooling operation state, wherein the main refrigerant flows to the main heat-source-side heat exchanger, the upstream-side main expansion valve, the sub-usage-side heat exchanger, the main usage side expansion valve in this order, and the main heating operation state, wherein the main refrigerant flows to the main usage-side heat exchanger, the upstream-side main expansion valve, the sub-usage-side heat exchanger, the downstream-side main expansion valve, and the main heat-source-side heat exchanger in this order,
• control the sub-flow-path switching valve to switch between the sub-cooling operation state and the sub-heating operation state,
• control the upstream side expansion valve to decompress the main refrigerant that flows between the main heat-source-side heat exchanger and the sub-usage-side heat exchanger during the main cooling operation states in to decompress the main refrigerant that flows between the main usage-side heat exchanger and the sub-usage-side heat exchanger during the main heating operation state,
• control the main usage side expansion valve to decompress the main refrigerant that flows between the sub-usage-side heat exchanger and the main usage-side heat exchanger during the main cooling operation state, and
• control the first downstream-side main expansion mechanism to decompress the main refrigerant that flows between the sub-usage-side heat exchanger and the main heat source-side heat exchanger during the main heating operation state.