JP5632629B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and particularly to an air conditioner using a non-azeotropic refrigerant mixture as a refrigerant.

  When the air conditioner is heated when the outside air temperature is low (for example, 1 to 3 ° C.), frost may be formed on the surface of the outdoor heat exchanger that absorbs heat from the outside air and vaporizes the refrigerant. When frost is formed on the surface of the outdoor heat exchanger, the endothermic effect for vaporizing the refrigerant is lowered, and the heating performance is lowered.

  In addition, when a non-azeotropic mixed refrigerant is used as the refrigerant, the evaporation temperature increases as the degree of dryness of the refrigerant increases. For this reason, comparing the refrigerant inlet side and the refrigerant outlet side of the outdoor heat exchanger, the refrigerant inlet side where the dryness of the refrigerant is small promotes vaporization of the refrigerant and frost formation compared to the refrigerant outlet side. Cheap.

  For this reason, in Patent Documents 1 and 2 below, when the frost formation state on the refrigerant inlet side of the outdoor heat exchanger is detected and frost formation on the refrigerant inlet side is detected, the refrigerant is discharged from the refrigerant compressor. In the invention, a high-temperature refrigerant is introduced from the refrigerant inlet side of the outdoor heat exchanger and defrosted using the heat of the refrigerant.

  When defrosting the outdoor heat exchanger by flowing high-temperature refrigerant from the refrigerant inlet side of the outdoor heat exchanger, the defrosting is easy because of the large temperature difference between the refrigerant and air on the refrigerant inlet side of the outdoor heat exchanger. However, as the temperature approaches the refrigerant outlet side of the outdoor heat exchanger, the temperature difference between the refrigerant and air becomes smaller, defrosting becomes difficult and the time required for defrosting becomes longer. Therefore, in the inventions described in Patent Documents 1 and 2, defrosting is started by allowing a high-temperature refrigerant to flow into the refrigerant inlet side of the outdoor heat exchanger at the stage of frost formation on the refrigerant inlet side of the outdoor heat exchanger, We are trying to shorten the defrosting time.

JP 7-151426 A JP-A-7-103623

  However, under the conditions of the outside air temperature (for example, 1 to 3 ° C.) where frost formation is a problem, the heat absorption efficiency is best when using the entire area of the outdoor heat exchanger, so it is designed appropriately. The refrigerant temperature in the outdoor heat exchanger is less than 0 ° C. even at the end of the temperature glide (end of evaporation), and the frosting amount is the largest on the refrigerant inlet side of the outdoor heat exchanger, but frost is formed in the entire outdoor heat exchanger. It becomes a state.

  In such a state, in the inventions described in Patent Documents 1 and 2, the defrosting operation is frequently performed and the heating operation is interrupted, and it is effective for defrosting on the refrigerant inlet side of the outdoor heat exchanger. However, it is difficult to defrost on the refrigerant outlet side of the outdoor heat exchanger, and it can be said that the defrosting time becomes longer.

  The present invention has been made in order to solve such problems, and its purpose is to keep the frost formation of the outdoor heat exchanger only on the refrigerant inlet side, thereby reducing the frequency of the defrosting operation and shortening the defrosting operation. It is to provide an air conditioner that can be completed in time.

A feature according to the embodiment of the present invention is that a refrigerant compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger are connected by a refrigerant pipe, and a non-azeotropic refrigerant mixture is used as a refrigerant. In the air conditioner to be used, a frost detection unit that detects a frost state of the outdoor heat exchanger, and a heating unit that heats the refrigerant that flows out of the outdoor heat exchanger during the heating operation and is sucked into the refrigerant compressor A suction temperature detection unit for detecting the temperature of the refrigerant after being heated by the heating means, and a part of the refrigerant discharged from the refrigerant compressor When the value of the frosting state detected by the frosting detection unit during the heating operation is equal to or greater than a predetermined value, the outdoor heat is transmitted to the refrigerant inlet side of the outdoor heat exchanger during the heating operation. Cool outflowing from the exchanger and sucked into the refrigerant compressor The refrigerant with the with heating by the heating means, the detection value of the suction temperature detecting unit by increasing the opening degree of the expansion device so that the set value, performs a heat absorption at the refrigerant inlet side of the outdoor heat exchanger Control is performed so as not to absorb heat at the outlet side, and the value of the frosting state detected by the frosting detection unit when the suction temperature of the refrigerant sucked into the refrigerant compressor is equal to or lower than a predetermined temperature. When the temperature exceeds the second predetermined value, heating by the heating means is stopped, and a part of the refrigerant discharged from the refrigerant compressor is caused to flow from the refrigerant inlet side of the outdoor heat exchanger through the bypass passage. And a control unit for controlling the operation.

  According to the present invention, frost formation of the outdoor heat exchanger can be stopped only on the refrigerant inlet side, and the frequency of the defrosting operation can be reduced and the defrosting operation can be completed in a short time.

It is a mimetic diagram showing the air harmony machine of a 1st embodiment of the present invention. It is sectional drawing which shows the flow-path structure in an outdoor heat exchanger. It is a schematic diagram which shows the air conditioner of the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the air conditioner 1 includes a refrigerant compressor 2, a four-way valve 3, an indoor heat exchanger 4, an expansion device 5, and an outdoor heat exchanger 6, and each of these members. Are communicated through the refrigerant pipe 7, and a non-azeotropic refrigerant mixture is used as the refrigerant. Furthermore, the air conditioner 1 includes a temperature sensor 8 that functions as a frost detection unit, a waste heat utilization heat exchanger 9 that is a heating unit, a superheat degree sensor 10 that is a suction temperature detection unit, a bypass passage 11, A first switching valve 12, a second switching valve 13, a third switching valve 14, a pressure reducing device 15, and a control unit 16 are provided.

  The refrigerant compressor 2 sucks in the refrigerant circulating in the air conditioner 1 and compresses the sucked refrigerant into a high temperature and high pressure state, and discharges the high temperature and high pressure refrigerant toward the four-way valve 3.

  The four-way valve 3 switches the flow direction of the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 so as to be the indoor heat exchanger 4 during the heating operation, and switches to the outdoor heat exchanger 6 during the cooling operation.

  The indoor heat exchanger 4 is installed indoors, receives air blown by a fan (not shown), functions as a condenser during the heating operation, and dissipates heat in the room, and functions as an evaporator during the cooling operation, and absorbs heat from the room.

  The expansion device 5 decompresses the refrigerant condensed and liquefied by the indoor heat exchanger 4 or the outdoor heat exchanger 6 that functions as a condenser, and sends it to the outdoor heat exchanger 6 or the indoor heat exchanger 4 that functions as an evaporator. .

  The outdoor heat exchanger 6 is installed outdoors, receives air blown by a fan (not shown), functions as an evaporator during heating operation and absorbs heat from the outside air, and functions as a condenser during cooling operation and dissipates heat into the outside air.

  The refrigerant pipe 7 is a pipe through which refrigerant flows through the refrigerant compressor 2, the four-way valve 3, the indoor heat exchanger 4, the expansion device 5, and the outdoor heat exchanger 6. Between the outdoor heat exchanger 6 and the four-way valve 3 in the refrigerant pipe 7, a first switching valve 12 for interrupting the flow of the refrigerant is provided.

  The temperature sensor 8 functioning as a frost formation detection unit detects the temperature on the refrigerant inlet side of the outdoor heat exchanger 6 and transmits the detected value to the control unit 16. Based on the value detected by the temperature sensor 8, the control unit 16 determines the frosting state on the surface of the outdoor heat exchanger 6 during the heating operation.

  The exhaust heat utilization heat exchanger 9 that is a heating means heats the refrigerant that has flowed out of the outdoor heat exchanger 6 during the heating operation using the exhaust heat from the refrigerant compressor 2. The exhaust heat utilization heat exchanger 9 is formed by piping a part of the refrigerant pipe 7 a through which the refrigerant flows so as to be wound around the refrigerant compressor 2. One end of the refrigerant pipe 7 a is connected between the outdoor heat exchanger 6 and the first switching valve 12 in the refrigerant pipe 7, and the other end is connected to the inlet side of the refrigerant compressor 2 in the refrigerant pipe 7. In the middle of the refrigerant pipe 7a, a second switching valve 13 for interrupting the flow of the refrigerant in the refrigerant pipe 7a is provided.

  The superheat degree sensor 10 which is a suction temperature detection unit is provided on the inlet side of the refrigerant compressor 2 and detects the suction temperature of the refrigerant sucked into the refrigerant compressor 2.

  The bypass passage 11 is a passage that guides a part of the refrigerant discharged from the refrigerant compressor 2 to the refrigerant inlet side of the outdoor heat exchanger 6 during heating operation, and one end is the outlet side of the refrigerant compressor 2 in the refrigerant pipe 7. The other end of the refrigerant pipe 7 is connected to the inlet side of the outdoor heat exchanger 6. In the middle of the bypass passage 11, a third switching valve 14 that interrupts the refrigerant flow in the bypass passage 11 and a decompression device 15 that decompresses the refrigerant flowing in the bypass passage 11 are provided.

  The control unit 16 is connected to the four-way valve 3, the expansion device 5, the temperature sensor 8, the superheat degree sensor 10, the first switching valve 12, the second switching valve 13, and the third switching valve 14. The control unit 16 controls the switching of the four-way valve 3 according to the heating operation or the cooling operation, adjusts the opening degree of the expansion device 5 according to the detection results of the temperature sensor 8 and the superheat degree sensor 10, and the first to third switching valves 12. , 13 and 14 are controlled.

  As shown in FIG. 2, the flow path 17 through which the refrigerant in the outdoor heat exchanger 6 flows is formed so that the refrigerant during the heating operation flows from the lower side to the upper side of the outdoor heat exchanger 6.

  In such a configuration, the control when the air conditioner 1 is heated under the condition of the outside air temperature (for example, 1 to 3 ° C.) in which frost formation on the surface of the outdoor heat exchanger 6 becomes a problem will be described. To do.

  When the heating operation is started, the four-way valve 3 is switched so that the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 flows toward the indoor heat exchanger 4. At the start of the heating operation, the first switching valve 12 is opened, and the second switching valve 13 and the third switching valve 14 are closed.

  For this reason, the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 flows into the indoor heat exchanger 4 through the four-way valve 3, exchanges heat with the indoor air, is condensed, and heats the indoor air. . The refrigerant condensed and liquefied in the indoor heat exchanger 4 is decompressed by the expansion device 5 and then flows into the outdoor heat exchanger 6. The liquid refrigerant flowing into the outdoor heat exchanger 6 evaporates by exchanging heat with the outside air, and the evaporated refrigerant is discharged from the outdoor heat exchanger 6 and is compressed through the four-way valve 3. It is sucked into the machine 2. The refrigerant sucked into the refrigerant compressor 2 is compressed and becomes a high-temperature and high-pressure refrigerant again, and flows into the indoor heat exchanger 4 through the four-way valve 3.

  The surface of the outdoor heat exchanger 6 may be frosted during the heating operation, and the frosting state in the outdoor heat exchanger 6 is detected by the temperature sensor 8. When the value indicating the frosting state detected by the temperature sensor 8 is equal to or higher than the set value (when the detected temperature is lower than the predetermined temperature), the refrigerant flows out of the outdoor heat exchanger 6 and enters the refrigerant compressor 2. An operation of heating the sucked refrigerant by the exhaust heat utilization heat exchanger 9 is executed by the control unit 16.

  During the operation of heating the refrigerant sucked into the refrigerant compressor 2, the first switching valve 12 is closed, the second switching valve 13 is opened, and the third switching valve 14 is maintained in the closed state. As a result, the refrigerant flowing out of the outdoor heat exchanger 6 flows through the refrigerant pipe 7 a to reach the exhaust heat utilization heat exchanger 9, and is sucked into the refrigerant compressor 2 after being heated by the exhaust heat utilization heat exchanger 9. Be turned.

  The temperature of the refrigerant sucked into the refrigerant compressor 2 is detected by the superheat degree sensor 10, and the control unit 16 adjusts the opening degree of the expansion device 5 so that the detection value of the superheat degree sensor 10 becomes a set value. To do. Specifically, when the temperature of the refrigerant heated by the exhaust heat utilization heat exchanger 9 and sucked into the refrigerant compressor 2 rises above a set value, the opening degree of the expansion device 5 is increased to increase the outdoor heat. The amount of refrigerant flowing into the exchanger 6 is increased, and control is performed so that the degree of superheat of the refrigerant sucked into the refrigerant compressor 2 becomes constant. As a result, the evaporating pressure and evaporating temperature of the refrigerant in the outdoor heat exchanger 6 are increased. When the evaporation temperature in the outdoor heat exchanger 6 rises, it becomes substantially the same as the outside air temperature of 0 ° C. or higher on the refrigerant outlet side of the outdoor heat exchanger 6 and does not absorb heat. For this reason, frost formation does not generate | occur | produce in the refrigerant | coolant exit side of the outdoor heat exchanger 6, and when there exists frost which has already formed frost, it will be in the state by which the frost is defrosted with external air.

  As described above, when the refrigerant sucked into the refrigerant compressor 2 is heated by the exhaust heat utilization heat exchanger 9, the frost formation region is set while absorbing heat at the refrigerant inlet side of the outdoor heat exchanger 6. The heating operation is limited to the refrigerant inlet side of the outdoor heat exchanger 6. Therefore, even when the temperature sensor 8 detects frost formation on the outdoor heat exchanger 6, the heating operation can be continued without immediately performing the defrosting operation. Moreover, since the temperature of the refrigerant sucked into the refrigerant compressor 2 is maintained at the set value, the heating performance is maintained in the same state as before the temperature sensor 8 detects the frosting state.

  When the frosting state of the outdoor heat exchanger 6 has progressed due to a decrease in the outside air temperature or the like, the heat absorption performance on the refrigerant inlet side of the outdoor heat exchanger 6 is deteriorated and heated by the exhaust heat utilization heat exchanger 9. However, the temperature of the refrigerant sucked into the refrigerant compressor 2 gradually decreases. Then, when the superheat sensor 10 detects that the suction temperature of the refrigerant sucked into the refrigerant compressor 2 has become equal to or lower than a predetermined temperature, the removal of the frost that has formed on the outdoor heat exchanger 6 is removed. The frost operation is executed by the control unit 16.

  During this defrosting operation, the first switching valve 12 is opened, the second switching valve 13 is closed, and the third switching valve 14 is opened.

  Thereby, on the other hand, the heating with the exhaust heat utilization heat exchanger 9 of the refrigerant | coolant which flowed out from the outdoor heat exchanger 6 is stopped. On the other hand, a part of the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 is depressurized by the decompression device 15 via the bypass passage 11 and then led to the refrigerant inlet side of the outdoor heat exchanger 6, and the outdoor heat It flows into the exchanger 6. When the high-temperature refrigerant discharged from the refrigerant compressor 2 flows into the refrigerant inlet side of the outdoor heat exchanger 6, the frost that forms on the outdoor heat exchanger 6 is defrosted by the heat of the refrigerant.

  The temperature of the high-temperature refrigerant that has flowed into the outdoor heat exchanger 6 decreases toward the refrigerant outlet side of the outdoor heat exchanger 6, and the defrosting performance decreases. However, since the frost formation region in the outdoor heat exchanger 6 is limited to the refrigerant inlet side, it is not necessary to perform defrosting on the refrigerant outlet side of the outdoor heat exchanger 6, and defrosting can be performed in a short time. .

  Further, as shown in FIG. 2, the flow path 17 through which the refrigerant in the outdoor heat exchanger 6 flows is such that the refrigerant during heating operation flows from the lower side (refrigerant inlet side) toward the upper side (refrigerant outlet side). Is formed. For this reason, the refrigerant flows into the flow path 17 from the lower side of the outdoor heat exchanger 6 and flows to the upper side. Therefore, the refrigerant is heated by the exhaust heat utilization heat exchanger 9 to suppress frost formation on the refrigerant outlet side of the outdoor heat exchanger 6 and at the refrigerant outlet side of the outdoor heat exchanger 6 (upper side of the outdoor heat exchanger 6). When the frost is defrosted by the outside air, the water generated by the defrost flows down and the frost on the lower side (refrigerant inlet side) of the outdoor heat exchanger 6 can be melted by the water that has flowed down. This reduces the amount of heat required for defrosting in the defrosting operation in which defrosting of the outdoor heat exchanger 6 is performed by flowing a high-temperature refrigerant into the refrigerant inlet side of the outdoor heat exchanger 6 via the bypass passage 11. And the defrosting operation time can be further shortened.

  In the present embodiment, when the superheat sensor 10 detects that the suction temperature of the refrigerant sucked into the refrigerant compressor 2 is equal to or lower than a predetermined temperature, the refrigerant heat by the exhaust heat utilization heat exchanger 9 is By stopping the heating and allowing a part of the refrigerant discharged from the refrigerant compressor 2 to flow from the refrigerant inlet side of the outdoor heat exchanger 6 through the bypass passage 11, frost that has formed on the outdoor heat exchanger 9 is defrosted. Like to do. However, when the value indicating the frosting state of the outdoor heat exchanger 6 detected by the temperature sensor 8 is equal to or higher than the second set value, the heating of the refrigerant by the exhaust heat utilization heat exchanger 9 is stopped and the refrigerant A part of the refrigerant discharged from the compressor 2 may be introduced from the refrigerant inlet side of the outdoor heat exchanger 6 through the bypass passage 11 to defrost the outdoor heat exchanger 6.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same component as the component of 1st Embodiment, and the overlapping description is abbreviate | omitted.

  The basic configuration of the air conditioner 1A of the second embodiment is the same as that of the air conditioner 1 of the first embodiment. The difference is that the refrigerant flows out of the outdoor heat exchanger 6 during the heating operation. This is a configuration of heating means for heating the refrigerant sucked into the compressor 2.

  The second embodiment is that a second bypass passage 18 is provided as a heating means for joining a part of the refrigerant discharged from the refrigerant compressor 2 with the refrigerant flowing out of the outdoor heat exchanger 6. One end of the second bypass passage 18 is connected to a portion of the refrigerant pipe 7 between the outdoor heat exchanger 6 and the four-way valve 3, and the other end is connected in the middle of the bypass passage 11.

  In the middle of the second bypass passage 18, a fourth switching valve 19 that interrupts the flow of the refrigerant in the second bypass passage 18 and a decompression device 20 that decompresses the refrigerant flowing in the second bypass passage 18 are provided. Yes.

  In the second embodiment, a control unit 16A is provided instead of the control unit 16, and the control unit 16A includes the four-way valve 3, the expansion device 5, the temperature sensor 8, the superheat degree sensor 10, and the third switching. A valve 14 and a fourth switching valve 19 are connected. The control unit 16A controls the switching of the four-way valve 3 according to the heating operation or the cooling operation, adjusts the opening degree of the expansion device 5 according to the detection results of the temperature sensor 8 and the superheat degree sensor 10, and the third and fourth switching valves 14. , 19 is controlled.

  In such a configuration, a description will be given of control when the air conditioner 1A is heated under a condition of an outside air temperature (for example, 1 to 3 ° C.) in which frost formation of the outdoor heat exchanger 6 causes a problem.

  When the heating operation is started, the four-way valve 3 is switched so that the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 flows toward the indoor heat exchanger 4. At the start of the heating operation, the third switching valve 14 and the fourth switching valve 19 are closed.

  For this reason, the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 flows into the indoor heat exchanger 4 through the four-way valve 3, exchanges heat with the indoor air, is condensed, and heats the indoor air. . The refrigerant condensed and liquefied in the indoor heat exchanger 4 is decompressed by the expansion device 5 and then flows into the outdoor heat exchanger 6. The liquid refrigerant flowing into the outdoor heat exchanger 6 evaporates by exchanging heat with the outside air, and the evaporated refrigerant is discharged from the outdoor heat exchanger 6 and is compressed through the four-way valve 3. It is sucked into the machine 2. The refrigerant sucked into the refrigerant compressor 2 is compressed and becomes a high-temperature and high-pressure refrigerant again, and flows into the indoor heat exchanger 4 through the four-way valve 3.

  The surface of the outdoor heat exchanger 6 may be frosted during the heating operation, and the frosting state in the outdoor heat exchanger 6 is detected by the temperature sensor 8. When the value indicating the frosting state detected by the temperature sensor 8 is greater than or equal to the set value, the refrigerant that has flowed out of the outdoor heat exchanger 6 and the refrigerant compressor 2 are discharged and flow through the second bypass passage 18. The controller 16 </ b> A performs an operation of combining the high-temperature refrigerant and heating the refrigerant sucked into the refrigerant compressor 2.

  During the operation of heating the refrigerant sucked into the refrigerant compressor 2, the fourth switching valve 19 is opened and the third switching valve 14 is maintained in the closed state. Thereby, the high-temperature refrigerant discharged from the refrigerant compressor 2 and flowing in the second bypass passage 18 merges with the refrigerant flowing out of the outdoor heat exchanger 6, and the temperature of the refrigerant sucked into the refrigerant compressor 2 is increased. To rise.

  The temperature of the refrigerant sucked into the refrigerant compressor 2 is detected by the superheat degree sensor 10, and the control unit 16A adjusts the opening degree of the expansion device 5 so that the detection value of the superheat degree sensor 10 becomes a set value. To do. Specifically, when the temperature of the refrigerant heated by joining the refrigerant flowing through the second bypass passage 18 and sucked into the refrigerant compressor 2 rises above a set value, the opening degree of the expansion device 5 Is increased, the amount of refrigerant flowing into the outdoor heat exchanger 6 is increased, and the evaporation temperature in the outdoor heat exchanger 6 is increased. When the evaporation temperature in the outdoor heat exchanger 6 rises, it becomes substantially the same as the outside air temperature of 0 ° C. or higher on the refrigerant outlet side of the outdoor heat exchanger 6 and does not absorb heat. For this reason, frost formation does not generate | occur | produce in the refrigerant | coolant exit side of the outdoor heat exchanger 6, and when there exists frost which has already formed frost, it will be in the state by which the frost is defrosted with external air.

  As described above, when the refrigerant flowing out of the outdoor heat exchanger 6 and sucked into the refrigerant compressor 2 is heated by joining the high-temperature refrigerant flowing through the second bypass passage 18, the outdoor heat exchanger is heated. While performing heat absorption at the refrigerant inlet side of 6, the heating operation is performed with the frost formation region limited to the refrigerant inlet side of the outdoor heat exchanger 6. Therefore, even when the temperature sensor 8 detects frost formation on the outdoor heat exchanger 6, the heating operation can be continued without immediately performing the defrosting operation. Moreover, since the temperature of the refrigerant sucked into the refrigerant compressor 2 is maintained at the set value, the heating performance is maintained in the same state as before the temperature sensor 8 detects the frosting state.

  When the frosting state of the outdoor heat exchanger 6 proceeds due to a decrease in the outside air temperature or the like, the heat absorption performance on the refrigerant inlet side of the outdoor heat exchanger 6 is reduced, and the high-temperature refrigerant flowing through the second bypass passage 18 The temperature of the refrigerant that merges and is sucked into the refrigerant compressor 2 gradually decreases. Then, when the superheat sensor 10 detects that the suction temperature of the refrigerant sucked into the refrigerant compressor 2 has become equal to or lower than a predetermined temperature, the removal of the frost that has formed on the outdoor heat exchanger 6 is removed. The frost operation is executed by the control unit 16A.

  During this defrosting operation, the third switching valve 14 is opened and the fourth switching valve 19 is closed.

  Thereby, a part of the high-temperature and high-pressure refrigerant discharged from the refrigerant compressor 2 is guided to the refrigerant inlet side of the outdoor heat exchanger 6 after being decompressed by the decompression device 15 via the bypass passage 11, and the outdoor heat It flows into the exchanger 6. When the high-temperature refrigerant discharged from the refrigerant compressor 2 flows into the refrigerant inlet side of the outdoor heat exchanger 6, the frost that forms on the outdoor heat exchanger 6 is defrosted by the heat of the refrigerant.

  The temperature of the high-temperature refrigerant that has flowed into the outdoor heat exchanger 6 decreases toward the refrigerant outlet side of the outdoor heat exchanger 6, and the defrosting performance decreases. However, since the frost formation region in the outdoor heat exchanger 6 is limited to the refrigerant inlet side, it is not necessary to perform defrosting on the refrigerant outlet side of the outdoor heat exchanger 6, and defrosting can be performed in a short time. .

  DESCRIPTION OF SYMBOLS 1 ... Air conditioner, 1A ... Air conditioner, 2 ... Refrigerant compressor, 3 ... Four-way valve, 4 ... Indoor heat exchanger, 5 ... Expansion device, 6 ... Outdoor heat exchanger, 7 ... Refrigerant piping, 8 ... Arrival Frost detection part (temperature sensor), 9 ... heating means, exhaust heat utilization heat exchanger, 10 ... suction temperature detection part (superheat degree sensor), 11 ... bypass passage, 16 ... control part, 16A ... control part, 17 ... flow Road, 18 ... heating means, second bypass passage

Claims (4)

In an air conditioner using a refrigerant compressor, a four-way valve, an indoor heat exchanger, an expansion device, and an outdoor heat exchanger in refrigerant piping and using a non-azeotropic refrigerant mixture as a refrigerant,
A frost detection unit for detecting the frost state of the outdoor heat exchanger;
Heating means for heating the refrigerant flowing out of the outdoor heat exchanger and sucked into the refrigerant compressor during heating operation;
A suction temperature detector that detects the temperature of the refrigerant after being heated by the heating means, the suction temperature of the refrigerant sucked into the refrigerant compressor;
A bypass passage for guiding a part of the refrigerant discharged from the refrigerant compressor to the refrigerant inlet side of the outdoor heat exchanger during heating operation;
When the value of the frosting state detected by the frosting detection unit during the heating operation becomes equal to or greater than a predetermined value, the refrigerant that flows out of the outdoor heat exchanger and is sucked into the refrigerant compressor by the heating means. In addition to heating, the opening of the expansion device is increased so that the detected value of the suction temperature detection unit becomes a set value, and heat is absorbed on the refrigerant inlet side of the outdoor heat exchanger and heat is absorbed on the refrigerant outlet side. The value of the frosting state detected when the suction temperature of the refrigerant sucked into the refrigerant compressor is equal to or lower than a predetermined temperature or detected by the frosting detection unit is a second predetermined value. A control unit that controls heating so that a part of the refrigerant discharged from the refrigerant compressor flows in from the refrigerant inlet side of the outdoor heat exchanger through the bypass passage when heating by the heating means is stopped When,
An air conditioner comprising: 2. The air conditioner according to claim 1, wherein the heating unit is an exhaust heat utilization heat exchanger that is disposed around the refrigerant compressor and heats the refrigerant by using exhaust heat of the refrigerant compressor. Machine. 2. The air conditioner according to claim 1, wherein the heating unit is a second bypass passage that joins a part of the refrigerant discharged from the refrigerant compressor with the refrigerant flowing out of the outdoor heat exchanger. The flow path through which the refrigerant in the outdoor heat exchanger flows is formed so that the refrigerant flows from the lower side to the upper side of the outdoor heat exchanger during heating operation. The air conditioner according to any one of 3.

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