# US 11,994,325 B2 · Control device, refrigerator, control method, and abnormality detection method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,325 B2 - Document ID: US11994325B2 - Status: Granted - Kind: B2 - Application number: 17/266,012 - Filed: 2019-06-18 - Published: 2021-09-30 - Granted: 2024-05-28 - Earliest claimed: 2018-08-13 - Assignees: Mitsubishi Heavy Industries Thermal Systems, Ltd. - Applicants: Mitsubishi Heavy Industries Thermal Systems, Ltd. - Inventors: Ryosuke Suemitsu; Akimasa Yokoyama; Takahiro Kono; Yasushi Hasegawa - Web page: https://patentgrep.com/patent/US11994325B2 ## CPC - F25B 49/005: {of safety devices (F25B49/02 and F25B49/04 take precedence)} - F25B 49/02: for compression type machines, plants or systems - F04D 27/001: {Testing thereof; Determination or simulation of flow characteristics; Stall or surge detection, e.g. condition monitoring} - F04D 27/0269: {by changing flow path between different stages or between a plurality of compressors; load distribution between compressors} - F25B 1/053: of turbine type - F25B 41/20: Disposition of valves, e.g. of on-off valves or flow control valves (expansion valves F25B41/31) - F25B 41/31: Expansion valves - H02P 5/46: for speed regulation of two or more dynamo-electric motors in relation to one another - F25B 25/005: {using primary and secondary systems} - F25B 49/022: {Compressor control arrangements} - F25B 2339/047: Water-cooled condensers - F25B 2400/0403: for condensers - F25B 2400/06: Several compression cycles arranged in parallel - F25B 2500/06: Damage - F25B 2600/0261: external to the compressor - F25B 2600/2501: Bypass valves - F25B 2600/2513: Expansion valves - F25B 2700/151: of the compressor motor - F25B 2700/197: of the evaporator - F25B 2700/21163: of the refrigerant at the outlet of the condenser - F25B 2700/21172: at the inlet - F25B 2700/21173: at the outlet - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract The present invention provides a control device for detecting an abnormal operation state of a compressor in a parallel refrigerator. The control device is a control device for a refrigerator that includes a plurality of compressors connected in parallel, and detects occurrence of surging and occurrence of droplet suction on the basis of a deviation between values of currents flowing through electric motors that is configured to drive each of the plurality of compressors, and an operation point indicated by the air volume and the compression ratio of the plurality of compressors. ## Claims ### Claim 1 A controller for a refrigerator provided with a plurality of compressors connected in parallel, wherein the controller detects occurrence of surging and occurrence of droplet suction, while distinguishing the surging from the droplet suction, on the basis of a deviation between values of currents flowing through electric motors that are configured to drive each of the plurality of compressors, and an operation point indicated by an air volume and a compression ratio of the plurality of compressors. ### Claim 2 (depends on 1) The controller according to claim 1, wherein the controller is configured to determine that the surging occurs in at least one of the plurality of compressors when the deviation between the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is smaller than a predetermined reference. ### Claim 3 (depends on 2) The controller according to claim 2, wherein the refrigerator is configured to include a bypass pipe that connects together a discharge side and a suction side of the plurality of compressors, and a bypass valve that is provided in the bypass pipe, and when the occurrence of the surging is detected by an abnormality detector, control to open the bypass valve is performed by a protection controller. ### Claim 4 (depends on 2) The controller according to claim 2, wherein the controller is configured to determine that the droplet suction occurs in at least one of the plurality of compressors from an evaporator provided in the refrigerator when the deviation between the values of currents is equal to or larger than the predetermined threshold value and the operation point indicates that the air volume is larger than the predetermined reference. ### Claim 5 (depends on 2) The controller according to claim 2, wherein the controller is configured to maintain a current operation until the deviation between the values of currents becomes smaller than the predetermined threshold value when the occurrence of the droplet suction is detected. ### Claim 6 (depends on 1) The controller according to claim 1, wherein the refrigerator is configured to include a bypass pipe that connects together a discharge side and a suction side of the plurality of compressors, and a bypass valve that is provided in the bypass pipe, and when the occurrence of the surging is detected by an abnormality detector, control to open the bypass valve is performed by a protection controller. ### Claim 7 (depends on 6) The controller according to claim 6, wherein when a state in which the deviation between the values of currents becomes equal to or larger than a predetermined threshold value continues even though a predetermined time elapses after the occurrence of the surging is detected by the abnormality detector, the control to open the bypass valve is stopped by the protection controller. ### Claim 8 (depends on 7) The controller according to claim 7, wherein the controller is configured to determine that the droplet suction occurs in at least one of the plurality of compressors from an evaporator provided in the refrigerator when the deviation between the values of currents is equal to or larger than the predetermined threshold value and the operation point indicates that the air volume is larger than the predetermined reference. ### Claim 9 (depends on 7) The controller according to claim 7, wherein the controller is configured to maintain a current operation until the deviation between the values of currents becomes smaller than the predetermined threshold value when the occurrence of the droplet suction is detected. ### Claim 10 (depends on 6) The controller according to claim 6, wherein the controller is configured to determine that the droplet suction occurs in at least one of the plurality of compressors from an evaporator provided in the refrigerator when the deviation between the values of currents is equal to or larger than the predetermined threshold value and the operation point indicates that the air volume is larger than the predetermined reference. ### Claim 11 (depends on 6) The controller according to claim 6, wherein the controller is configured to maintain a current operation until the deviation between the values of currents becomes smaller than the predetermined threshold value when the occurrence of the droplet suction is detected. ### Claim 12 (depends on 1) The controller according to claim 1, wherein the controller is configured to determine that the droplet suction occurs in at least one of the plurality of compressors from an evaporator provided in the refrigerator when the deviation between the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is larger than the predetermined reference. ### Claim 13 (depends on 1) The controller according to claim 1, wherein the controller is configured to maintain a current operation until the deviation between the values of currents becomes smaller than a predetermined threshold value when the occurrence of the droplet suction is detected. ### Claim 14 (depends on 1) The controller according to claim 1, wherein the controller is configured to decrease an opening degree of an expansion valve included in the refrigerator when the deviation between the values of currents does not become smaller than a predetermined threshold value even though a predetermined time elapses after the occurrence of the droplet suction is detected. ### Claim 15 A refrigerator provided with a plurality of compressors connected in parallel, the refrigerator comprising: a controller that detects occurrence of surging and occurrence of droplet suction, while distinguishing the surging from the droplet suction, on the basis of a deviation between values of currents flowing through electric motors that are configured to drive each of the plurality of compressors, and an operation point indicated by an air volume and a compression ratio of the plurality of compressors. ### Claim 16 A controller for a refrigerator provided with a plurality of compressors connected in parallel, wherein the controller determines that surging, and not droplet suction, occurs in at least one of the plurality of compressors when a deviation between values of currents flowing through electric motors that are configured to drive each of the plurality of compressors, is equal to or larger than a predetermined threshold value, and an operation point indicated by an air volume and a compression ratio of the plurality of compressors indicates that the air volume is smaller than a predetermined reference. ### Claim 17 A controller for a refrigerator provided with a plurality of compressors connected in parallel, wherein the controller determines that droplet suction, and not surging, occurs in at least one of the plurality of compressors from an evaporator provided in the refrigerator when a deviation between values of currents flowing through electric motors that are configured to drive each of the plurality of compressors, is equal to or larger than a predetermined threshold value, and an operation point indicated by an air volume and a compression ratio of the plurality of compressors indicates that the air volume is larger than a predetermined reference. ### Claim 18 A control method for a refrigerator provided with a plurality of compressors connected in parallel, the control method comprising: acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors; calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors; detecting occurrence of surging or droplet suction, while distinguishing the surging from the droplet suction, on the basis of a deviation between a plurality of the values of currents and the operation point; performing a predetermined surging protection operation when the occurrence of the surging is detected; and maintaining a current operation state when the droplet suction is detected. ### Claim 19 An abnormality detection method for a refrigerator provided with a plurality of compressors connected in parallel, the abnormality detection method comprising: acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors; calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors; and determining that surging, and not droplet suction, occurs in at least one of the plurality of compressors when a deviation between a plurality of the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is smaller than a predetermined reference. ### Claim 20 An abnormality detection method for a refrigerator provided with a plurality of compressors connected in parallel, the abnormality detection method comprising: acquiring values of currents flowing through electric motors that are configured to drive each of the plurality of compressors; calculating an operation point indicated by an air volume and a compression ratio of the plurality of compressors; and determining that droplet suction, not surging, occurs in at least one of the plurality of compressors when a deviation between a plurality of the values of currents is equal to or larger than a predetermined threshold value and the operation point indicates that the air volume is larger than a predetermined reference.