# US 9,518,754 B2 · Air-conditioning apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,754 B2 - Document ID: US9518754B2 - Status: Granted - Kind: B2 - Application number: 14/354,668 - Filed: 2012-01-24 - Published: 2014-09-04 - Granted: 2016-12-13 - Earliest claimed: 2012-01-24 - Assignees: Mitsubishi Electric Corporation - Applicants: Shinichi Wakamoto; Naofumi Takenaka; Koji Yamashita; Osamu Morimoto; Hirofumi Koge - Inventors: Shinichi Wakamoto; Naofumi Takenaka; Koji Yamashita; Osamu Morimoto; Hirofumi Koge - Web page: https://patentgrep.com/patent/US9518754B2 ## CPC - F24F 11/42: of outdoor units - F24F 11/30: for purposes related to the operation of the system, e.g. for safety or monitoring - F25B 13/00: Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02) - F25B 47/022: {hot gas defrosting} - F25B 2313/005: Outdoor unit expansion valves - F25B 2313/006: two pipes connecting the outdoor side to the indoor side with multiple indoor units - F25B 2313/02322: during defrosting - F25B 2313/0233: in parallel arrangements - F25B 2313/0253: in parallel arrangements - F25B 2313/02741: using one four-way valve - F25B 2400/13: Economisers - F25B 2600/2501: Bypass valves - F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02) - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract A first flow switching device causes part of a refrigerant discharged from an injection compressor to flow through a first bypass pipe and be supplied to an outdoor heat exchanger targeting for defrosting. A second flow switching device causes part of the refrigerant supplied to the outdoor heat exchanger targeting for defrosting to enter a second bypass pipe. ## Claims ### Claim 1 An air-conditioning apparatus including a main pipe that connects at least one indoor unit and an outdoor unit such that a refrigerant circulates therethrough, the air-conditioning apparatus further comprising: an indoor heat exchanger provided in the at least one indoor unit; a first flow control valve configured to control a flow rate of the refrigerant entering the indoor heat exchanger; an injection compressor including an injection port allowing part of the refrigerant circulating to be injected therethrough into the refrigerant undergoing compression; a refrigerant flow switching device configured to switch between a cooling operation and a heating operation; a plurality of outdoor heat exchangers provided in the outdoor unit and connected in parallel; a first bypass pipe having a first end connected between the injection compressor and the refrigerant flow switching device and a second end connected to first ones of inlet and outlet sides of the plurality of outdoor heat exchangers; a first bypass flow control valve provided to the first bypass pipe and configured to control a flow rate of the refrigerant; a second bypass pipe having a first end connected to the injection port or a pipe connected to the injection port and a second end connected to second ones of the inlet and outlet sides of the plurality of outdoor heat exchangers; a first flow switching device configured to switch a flow of the refrigerant to the main pipe or the first bypass pipe; and a second flow switching device configured to switch the flow of the refrigerant to the main pipe or the second bypass pipe, wherein in a defrosting operation of removing frost in any of the plurality of outdoor heat exchangers, the first flow switching device causes part of the refrigerant discharged from the injection compressor to flow through the first bypass pipe and decompress thereof by the first bypass flow control valve, and the refrigerant is supplied to an outdoor heat exchanger comprising the plurality of outdoor heat exchangers and targeting for defrosting, and the second flow switching device causes part of the refrigerant supplied to the outdoor heat exchanger targeting for defrosting to enter the second bypass pipe. ### Claim 2 (depends on 1) The air-conditioning apparatus of claim 1, wherein in the heating operation, the outdoor heat exchanger comprising the plurality of outdoor heat exchangers and targeting for defrosting exchanges heat while the refrigerant flows in a direction parallel to a direction in which outside air flows, and an outdoor heat exchanger comprising the plurality of outdoor heat exchangers and not targeting for defrosting exchanges heat while the refrigerant flows in a direction opposite to the direction in which the outside air flows. ### Claim 3 (depends on 1) The air-conditioning apparatus of claim 1, wherein each of the first flow switching device and the second flow switching device includes a two-way valve openable and closable independently of a magnitude of a pressure at each of an inlet and an outlet of the valve. ### Claim 4 (depends on 3) The air-conditioning apparatus of claim 3, wherein each of the first flow switching device and the second flow switching device is configured to stop the flow of the refrigerant in only one direction. ### Claim 5 (depends on 4) The air-conditioning apparatus of claim 4, wherein each of the first flow switching device and the second flow switching device is configured to stop the flow in a direction in which the refrigerant flows from the outdoor heat exchangers toward the main pipe. ### Claim 6 (depends on 1) The air-conditioning apparatus of claim 1, further comprising a second bypass flow control valve disposed on the second bypass pipe and configured to control the flow rate of the refrigerant. ### Claim 7 (depends on 1) The air-conditioning apparatus of claim 1, further comprising: a third bypass pipe having a first end connected between the outdoor heat exchangers and the first flow control valve and a second end connected to the injection port; a refrigerant heat exchanger configured to exchange heat between the refrigerant flowing between the outdoor heat exchangers and the first flow control valve and the refrigerant flowing in the third bypass pipe; and an injection flow control valve configured to control the flow rate of the refrigerant flowing in the third bypass pipe, wherein the first end of the second bypass pipe is connected to the third bypass pipe. ### Claim 8 (depends on 7) The air-conditioning apparatus of claim 7, wherein the first end of the second bypass pipe is connected to the third bypass pipe ahead of the refrigerant heat exchanger. ### Claim 9 (depends on 7) The air-conditioning apparatus of claim 7, further comprising: a temperature sensor configured to measure a temperature of the refrigerant discharged from the injection compressor, wherein when a value measured by the temperature sensor is equal to or higher than a predetermined temperature, an opening degree of the injection flow control valve is increased, and when the value measured by the temperature sensor is lower than the predetermined temperature, the opening degree of the injection flow control valve is reduced. ### Claim 10 (depends on 7) The air-conditioning apparatus of claim 7, further comprising: an outdoor flow control valve disposed between the refrigerant heat exchanger and the first flow switching device and configured to control the flow rate of the refrigerant; and a first pressure sensor configured to sense a pressure at a location between the first flow control valve and the refrigerant heat exchanger and between a branch point to the third bypass pipe and the first flow control valve, wherein an opening degree of the outdoor flow control valve is controlled on a basis of a value detected by the first pressure sensor. ### Claim 11 (depends on 1) The air-conditioning apparatus of claim 1, further comprising a second pressure sensor configured to sense a pressure of the refrigerant discharged from the injection compressor, wherein an opening degree of the first bypass flow control valve is controlled on a basis of a value detected by the second pressure sensor. ### Claim 12 (depends on 1) The air-conditioning apparatus of claim 1, wherein the plurality of outdoor heat exchangers are divided into upper and lower outdoor heat exchangers, after the defrosting operation is performed on the upper outdoor heat exchanger out of the divided outdoor heat exchangers, the defrosting operation is performed on the lower outdoor heat exchanger out of the divided outdoor heat exchangers. ### Claim 13 (depends on 1) The air-conditioning apparatus of claim 1, wherein the indoor heat exchanger and the first flow control valve are accommodated in each indoor unit, the injection compressor, the refrigerant flow switching device, the plurality of outdoor heat exchangers, the first bypass pipe, the second bypass pipe, the first flow switching device, and the second flow switching device are accommodated in the outdoor unit, and the outdoor unit is connected to the at least one indoor unit. ### Claim 14 (depends on 1) The air-conditioning apparatus of claim 1, wherein the refrigerant discharged from the injection compressor partially passes the first bypass pipe and the rest of the discharged refrigerant enters the indoor heat exchanger through the main pipe, thereby performing the defrosting operation and the heating operation simultaneously.