Air conditioner

Abstract

According to one embodiment, an air conditioner carries out a heating operation, a cooling operation, a cooling/heating mixed operation in which a higher priority is given to cooling, and a cooling/heating mixed operation in which a higher priority is given to heating.

What is claimed is: 
     
         1 . An air conditioner comprising:
 an outdoor unit including a compressor which circulates a refrigerant, an outdoor side heat exchanger, and a first expansion valve;   a heat exchange unit including a plurality of intermediate heat exchangers which carry out heat exchange between the refrigerant and a heat medium, and second expansion valves corresponding to the plurality of intermediate heat exchangers;   indoor units each of which includes an indoor side heat exchanger which carries out heat exchange between the heat medium and room air;   a valve unit including flow path change-over valves each of which makes one of the heat medium cooled by the intermediate heat exchanger and the heat medium heated by the intermediate heat exchanger flow into the indoor side heat exchanger; and   a control unit including controllers each of which controls each of the units, wherein   the outdoor unit, the heat exchange unit, the indoor units, and the valve unit are individually cased separately from each other,   the outdoor unit and the heat exchange unit are connected to each other by a liquid pipe which sends a condensate liquid condensed by the outdoor side heat exchanger to the heat exchange unit or sends a condensate liquid condensed by the intermediate heat exchanger to the outdoor unit, a suction gas pipe which sends the refrigerant evaporated by the intermediate heat exchanger to the outdoor unit, and a discharged gas pipe which sends a discharged gas compressed by the compressor to the heat exchange unit,   the control unit   carries out a heating operation by making the discharged gas flow into the intermediate heat exchanger,   carries out a cooling operation by condensing the discharged gas in the outdoor side heat exchanger and making the condensed condensate liquid flow into the intermediate heat exchanger through the second expansion valve,   carries out a cooling-prioritized cooling/heating-mixed operation by making part of the discharged gas flow into one of the plurality of intermediate heat exchangers to thereby condense the part of the discharged gas, condensing the remainder of the discharged gas in the outdoor side heat exchanger, mixing the condensed condensate liquid with the refrigerant condensed in the intermediate heat exchanger through the liquid pipe, and making the mixed condensate liquid flow into the other of the intermediate heat exchangers through the second expansion valve to thereby evaporate the mixed condensate liquid, and   carries out a heating-prioritized cooling/heating-mixed operation by making the discharged gas flow into one of the plurality of intermediate heat exchangers to thereby condense the discharged gas, making part of the discharged gas flow into the outdoor side heat exchanger through the liquid pipe to thereby evaporate the part of the discharged gas, and making the remainder of the condensate liquid flow into the other of the intermediate heat exchangers through the second expansion valve to thereby evaporate the remainder of the condensate liquid.   
     
     
         2 . The air conditioner of  claim 1 , wherein
 regarding a piping diameter of piping connecting the outdoor unit and the heat exchange unit to each other, a relationship “the suction gas pipe>the discharged gas pipe>the liquid pipe” is established.   
     
     
         3 . The air conditioner of  claim 2 , wherein
 at least one of the plurality of intermediate heat exchangers is a cooling intermediate heat exchanger which cools the refrigerant at the time of the cooling operation, and the other of the intermediate heat exchangers is a heating intermediate heat exchanger which heats the refrigerant at the time of the heating operation,   the discharged gas pipe is connected to the heating intermediate heat exchanger,   the suction gas pipe is connected to the cooling intermediate heat exchanger, and   the liquid pipe is connected to the heating intermediate heat exchanger and the cooling intermediate heat exchanger.   
     
     
         4 . The air conditioner of  claim 3 , further comprising a third expansion valve in the heat exchange unit, wherein
 the third expansion valve is provided between the suction gas pipe and the cooling intermediate heat exchanger.   
     
     
         5 . The air conditioner of  claim 4 , wherein
 the third expansion valve operates on the basis of one of an inlet temperature of the cooling intermediate heat exchanger and an evaporation gas saturation temperature obtained by converting the outlet pressure of the cooling intermediate heat exchanger into a saturation temperature.   
     
     
         6 . The air conditioner of  claim 1 , wherein
 the intermediate heat exchanger is a plate heat exchanger formed by laminating plates,   the plurality of plate heat exchangers include a plurality of cooling intermediate heat exchangers which cool the heat medium and a heating intermediate heat exchanger of a number less than the number of the plurality of cooling intermediate heat exchangers,   each of the cooling intermediate heat exchangers is installed in such a manner that the refrigerant flows upwardly in a direction perpendicular to an installation surface, and   the heating intermediate heat exchanger is installed in such a manner that the refrigerant flows in a horizontal direction relatively to the installation surface.   
     
     
         7 . The air conditioner of  claim 1 , wherein
 the outdoor unit includes an outdoor air temperature sensor which detects an outdoor air temperature, and   the controller selects one of the heating operation, the cooling operation, the cooling-prioritized cooling/heating-mixed operation, and the heating-prioritized cooling/heating-mixed operation on the basis of a percentage of cooling demand or heating demand on the indoor units and the outdoor air temperature detected by the outdoor air temperature sensor to thereby operate the outdoor unit.   
     
     
         8 . The air conditioner of  claim 7 , wherein
 when it is assumed that the outdoor air temperature detected by the outdoor air temperature sensor is TO, and a first specified temperature and a second specified temperature each specifying a range of the outdoor air temperature are TH and TL, respectively,   in a case where a condition “TL<TO<TH” is given, while the outdoor unit is made to carry out the cooling-prioritized cooling/heating-mixed operation, when the percentage of the heating demand on the indoor units becomes greater than or equal to a first threshold, the controller switches the operation of the outdoor unit from the cooling-prioritized cooling/heating-mixed operation to the heating-prioritized cooling/heating-mixed operation, while the outdoor unit is made to carry out the heating-prioritized cooling/heating-mixed operation, when the percentage of the cooling demand on the indoor units becomes greater than or equal to the first threshold, switches the operation of the outdoor unit from the heating-prioritized cooling/heating-mixed operation to the cooling-prioritized cooling/heating-mixed operation,   in a case where a condition “TO≥TH” is given, when the outdoor unit is made to carry out the cooling-prioritized cooling/heating-mixed operation, even if the percentage of the heating demand on the indoor units becomes greater than or equal to the first threshold, makes the outdoor unit continuously carry out the cooling-prioritized cooling/heating-mixed operation, and   in a case where a condition “TO≤TL” is given, when the outdoor unit is made to carry out the heating-prioritized cooling/heating-mixed operation, even if the percentage of the cooling demand on the indoor units becomes greater than or equal to the first threshold, makes the outdoor unit continuously carry out the heating-prioritized cooling/heating-mixed operation.   
     
     
         9 . The air conditioner of  claim 8 , wherein
 in the case where the condition “TO≥TH” is given, when the percentage of the heating demand on the indoor units becomes greater than or equal to a second threshold greater than the first threshold, the controller switches the operation of the outdoor unit from the cooling-prioritized cooling/heating-mixed operation to the heating-prioritized cooling/heating-mixed operation, and   in the case where the condition “TO≤TL” is given, when the percentage of the cooling demand becomes greater than or equal to a third threshold greater than the first threshold, switches the operation of the outdoor unit from the heating-prioritized cooling/heating-mixed operation to the cooling-prioritized cooling/heating-mixed operation.   
     
     
         10 . The air conditioner of  claim 1 , wherein
 the heat exchange unit includes a temperature sensor which detects a temperature of the heat medium on the downstream side of the intermediate heat exchanger,   the control unit stores therein setting of a target temperature of the heat medium for each of operation modes at the time of the cooling operation and at the time of the heating operation, acquires the temperature of the heat medium detected by the temperature sensor, and controls a rotational speed of the compressor on the basis of the acquired temperature and the target temperature,   the operation modes include a first mode and a second mode in which an operation is carried out with a higher degree of power saving than the first mode, and   the target temperature of the second mode at the time of the cooling operation is set higher than the target temperature of the first mode, and the target temperature of the second mode at the time of the heating operation is set lower than the target temperature of the first mode.   
     
     
         11 . The air conditioner of  claim 10 , wherein
 the outdoor unit is connected to a control panel, and   the air conditioner makes a transition from the first mode to the second mode on the basis of an instruction of the control panel.   
     
     
         12 . The air conditioner of  claim 10 , wherein
 the valve unit includes communication means for carrying out communication with each of the plurality of indoor units connected thereto, and   the control unit acquires an operating state of each of the plurality of indoor units through the valve unit, and makes the air conditioner make a transition from the first mode to the second mode on the basis of the acquired operating state of each of the plurality of indoor units.