# US 2017/0254569 A1 · Two-stage pressure buildup refrigeration cycle apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0254569 A1 - Document ID: US20170254569A1 - Status: Published application - Kind: A1 - Application number: 15/504,033 - Filed: 2015-08-28 - Published: 2017-09-07 - Earliest claimed: 2014-09-05 - Assignees: Denso Corporation - Applicants: Denso Corporation - Inventors: Yasutaka KURODA - Web page: https://patentgrep.com/patent/US20170254569A1 ## CPC - F25B 1/10: with multi-stage compression (with cascade operation F25B7/00) - F25B 1/00: Compression machines, plants or systems with non-reversible cycle (F25B3/00, F25B5/00, F25B6/00, F25B7/00, F25B9/00 take precedence) - F25B 9/10: with several cooling stages - F25B 49/022: {Compressor control arrangements} - F25B 49/027: {Condenser control arrangements} - F25B 49/025: {Motor control arrangements} - F25B 2400/13: Economisers - F25B 2600/111: of condenser fans - F25B 2700/21161: of the fluid heated by the condenser - F25B 2700/21172: at the inlet - Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A two-stage pressure buildup refrigeration cycle apparatus has a low-pressure side compressor, a high-pressure side compressor, and a controller. The controller controls, for improving a COP, the low-pressure side compressor and the high-pressure side compressor in a COP improving operation mode in which a refrigerant discharge capacity of one of the low-pressure side compressor and the high-pressure side compressor is set based on a refrigerant discharge capacity of an other of the low-pressure side compressor and the high-pressure side compressor, when a required level of a refrigeration performance is low. The controller controls the low-pressure side compressor and the high-pressure side compressor in a high performance operation mode in which a refrigerant discharge capacity of the high-pressure side compressor is increased after increasing a refrigerant discharge capacity of the low-pressure side compressor, when the required level of the refrigeration performance is high. ## Claims ### Claim 1 A two-stage pressure buildup refrigeration cycle apparatus comprising: a low-pressure side compressor that compresses a low-pressure refrigerant to be an intermediate-pressure refrigerant and discharges the low-pressure refrigerant; a high-pressure side compressor that compresses the intermediate-pressure refrigerant discharged from the low-pressure side compressor to be a high-pressure refrigerant and discharges the high-pressure refrigerant; a condenser that performs a heat exchange between the high-pressure refrigerant discharged from the high-pressure side compressor and outside air, and induces the high-pressure refrigerant to radiate heat; a main expansion valve that decompresses and expands the high-pressure refrigerant, which flows out of the condenser after radiating heat, to be the low-pressure refrigerant; an auxiliary expansion valve that decompresses the high-pressure refrigerant, which flows out of the condenser after radiating heat, and guides the refrigerant to a suction side of the high-pressure side compressor; an evaporator that performs a heat exchange between the low-pressure refrigerant decompressed in the main expansion valve and blown air to be blown into an interior as a cooling target space, evaporates the low-pressure refrigerant, and guides the low-pressure refrigerant to flow to a suction side of the low-pressure side compressor; a condenser fan that blows the outside air toward the condenser; an evaporator fan that blows air for cooling the interior toward the evaporator; and a controller that controls the low-pressure side compressor, the high-pressure side compressor, the condenser fan, and the auxiliary expansion valve, wherein the controller controls, for improving a COP, the low-pressure side compressor and the high-pressure side compressor in a COP improving operation mode in which a refrigerant discharge capacity of one of the low-pressure side compressor and the high-pressure side compressor is set based on a refrigerant discharge capacity of another of the low-pressure side compressor and the high-pressure side compressor, when a required level of a refrigeration performance is low, and controls the low-pressure side compressor and the high-pressure side compressor in a high performance operation mode in which a refrigerant discharge capacity of the high-pressure side compressor is increased after increasing a refrigerant discharge capacity of the low-pressure side compressor, when the required level of the refrigeration performance is high, and the controller increases the refrigerant discharge capacity of the low-pressure side compressor after dissolving a restriction condition that restricts an increase of the refrigerant discharge capacity of the low-pressure side compressor, when the restriction condition is met in the high performance operation mode, and increases the refrigeration discharge capacity of the high-pressure side compressor after dissolving a restriction condition that restricts an increase of the refrigerant discharge capacity of the high-pressure side compressor, when the restriction condition is met in the high performance operation mode. ### Claim 2 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, wherein the controller increases an opening degree of the auxiliary expansion valve or increases an air volume blown by the condenser fan to dissolve the restriction condition restricting the increase of the refrigerant discharge capacity of the low-pressure side compressor when the restriction condition is met while the refrigerant discharge capacity of the low-pressure side compressor increasing, and the restriction condition restricting the increase of the refrigerant discharge capacity of the high-pressure side compressor when the restriction condition is met while the refrigerant capacity of the high-pressure side compressor increasing. ### Claim 3 (depends on 2) The two-stage pressure buildup refrigeration cycle apparatus according to claim 2, wherein the restriction condition restricting the increase of the refrigerant discharge capacity of the low-pressure side compressor and the restriction condition restricting the increase of the refrigerant discharge capacity of the high-pressure side compressor are met when a temperature of the high-pressure refrigerant exceeds a predetermined upper limit temperature, when a pressure of the high-pressure refrigerant exceeds a predetermined upper limit pressure, or when a driving current for driving an electric compressor configuring the low-pressure side compressor or the high-pressure side compressor exceeds a predetermined upper limit current. ### Claim 4 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, further comprising an intermediate heat exchanger that performs a heat exchange between the high-pressure refrigerant flowing out of the condenser and the refrigerant decompressed in the auxiliary expansion valve, wherein the auxiliary expansion valve decompresses and expands one flow of flows of the high-pressure refrigerant divided in a branch portion that divides the high-pressure refrigerant flowing out of the condenser, and guides the one flow to the intermediate heat exchanger, the main expansion valve decompresses and expands another flow of the flows of the high-pressure refrigerant divided in the branch portion and cooled by the intermediate heat exchanger, and the refrigerant after passing through the auxiliary expansion valve and the intermediate heat exchanger flows into the suction side of the high-pressure side compressor. ### Claim 5 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, wherein the controller, in the high performance operation mode, increases the refrigerant discharge capacity of the high-pressure side compressor after maximizing the refrigerant discharge capacity of the low-pressure side compressor. ### Claim 6 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, wherein the controller controls the low-pressure side compressor and the high-pressure side compressor in the COP improving operation mode when an absolute value of a temperature deviation between an air temperature in the interior as the target space and a target cooling temperature is smaller than a reference temperature deviation set in advance, and controls the low-pressure side compressor and the high-pressure side compressor in the high performance operation mode when the absolute value of the temperature deviation is larger than or equal to the reference temperature deviation. ### Claim 7 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, further comprising a door opening/closing detector that detects an opening or closing of a door of the interior to be cooled by the evaporator, wherein the controller controls the low-pressure side compressor and the high-pressure side compressor in the COP improving operation mode when the door is determined to be closed based on a signal from the door opening/closing detection portion, and the controller controls the low-pressure side compressor and the high-pressure side compressor in the high performance operation mode when the door is determined to be open based on a signal from the door opening/closing detection portion. ### Claim 8 (depends on 1) The two-stage pressure buildup refrigeration cycle apparatus according to claim 1, further comprising an operation panel that outputs an operation command to the controller to perform the high performance operation mode, wherein the controller controls the low-pressure side compressor and the high-pressure side compressor in the COP improving operation mode when the operation command for performing the high performance operation mode is not output from the operation panel and controls the low-pressure side compressor and the high-pressure side compressor in the high performance operation mode when the operation command for performing the high performance operation mode is output from the operation panel. ### Claim 9 (depends on 3) The two-stage pressure buildup refrigeration cycle apparatus according to claim 3, wherein the controller increases a rotation speed of the condenser fan or increases an opening degree of the auxiliary expansion valve when a temperature of the high-pressure refrigerant exceeds the upper limit temperature and thereby the restriction condition restricting the increase of the refrigerant discharge capacity of the low-pressure side compressor or the restriction condition restricting the increase of the refrigerant discharge capacity of the high-pressure side compressor is met and increases a rotation speed of the condenser fan when a driving current for the low-pressure side compressor or the high-pressure side compressor exceeds the upper limit current and thereby the restriction condition restricting the increase of the refrigerant discharge capacity of the low-pressure side compressor or the restriction condition restricting the increase of the refrigerant discharge capacity of the high-pressure side compressor is met. ### Claim 10 (depends on 9) The two-stage pressure buildup refrigeration cycle apparatus according to claim 9, wherein the controller increases a rotation speed of the condenser fan when a pressure of the high-pressure refrigerant exceeds the upper limit pressure and thereby the restriction condition restricting the increase of the refrigerant discharge capacity of the low-pressure side compressor or the restriction condition restricting the increase of the refrigerant discharge capacity of the high-pressure side compressor is met.