JP6634731B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner that performs air conditioning using a refrigeration circuit.

  BACKGROUND ART Conventionally, in an air conditioner, a defrosting operation has been performed to remove frost that has arrived at an outdoor heat exchanger. For example, as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-155261) and Patent Document 2 (Japanese Patent Application Laid-Open No. 2013-130341), frost on the outdoor heat exchanger is removed despite heating. Therefore, there is an air conditioner that performs a reverse cycle defrost operation in which a refrigerant is circulated from an outdoor heat exchanger to an indoor heat exchanger via an expansion mechanism.

  When the reverse cycle defrost operation described in Patent Literature 1 or Patent Literature 2 is performed, heat is taken from the refrigerant by melting the frost of the outdoor heat exchanger, so that the temperature of the refrigerant decreases and the defrosting time is reduced. There is a problem that the start-up performance at the time of return becomes longer or the start-up performance at the time of return is reduced.

  It is an object of the present invention to reduce the defrosting time in the reverse cycle defrost operation and to improve the startup performance at the time of return.

  An air conditioner according to a first aspect of the present invention includes a compressor, an indoor heat exchanger, an expansion mechanism and an outdoor heat exchanger. A refrigeration circuit capable of switching between a reverse cycle in which a refrigerant flows in the order of a heat exchanger, an expansion mechanism, and an indoor heat exchanger to repeat a vapor compression refrigeration cycle, and an indoor fan that generates an airflow of indoor air in the indoor heat exchanger. In the reverse cycle defrost operation in which the refrigerant flows into the refrigeration circuit in the reverse cycle to defrost the outdoor heat exchanger, during the period from the start of the reverse cycle defrost operation until the frost of the outdoor heat exchanger is completely melted, Drive the fan temporarily.

  In this air conditioner, the indoor fan is temporarily driven during the period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted. Heat exchange can be promoted between the cooling medium and the refrigerant that has been deprived of heat during defrosting.

  The air conditioner according to a second aspect of the present invention, in the air conditioner according to the first aspect, further includes an outdoor heat exchanger temperature sensor that measures an outdoor heat exchanger temperature of the outdoor heat exchanger. The reverse cycle defrost operation is performed depending on a period from a state where the temperature sensor for the outdoor heat exchanger detected by the temperature sensor detects a constant temperature near 0 ° C. to a time when the temperature detected by the temperature sensor for the outdoor heat exchanger starts to rise. It detects the period from the start until the frost of the outdoor heat exchanger is completely melted.

  In this air conditioner, the period from the time when the temperature sensor for the outdoor heat exchanger detects a constant temperature near 0 ° C. to the time when the temperature detected by the temperature sensor for the outdoor heat exchanger starts to rise is defined as the temperature sensor for the outdoor heat exchanger. Therefore, it is possible to reliably detect the period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted, with a simple configuration.

  An air conditioner according to a third aspect of the present invention is the air conditioner according to the first aspect or the second aspect, in which the indoor fan is continuously driven for a predetermined time from the start of the reverse cycle defrost operation.

  In this air conditioner, since the indoor fan is continuously driven for a predetermined time from the start of the reverse cycle defrost operation, the indoor fan is running even when switching from the normal cycle to the reverse cycle. The effect of the sound caused by switching to the reverse cycle can be suppressed. Therefore, for example, when switching from the forward cycle to the reverse cycle, the compressor may be switched without stopping, and by not stopping the compressor, the time required from the stop state at the time of switching to raising the operating frequency may be reduced. Can be shortened.

  An air conditioner according to a fourth aspect of the present invention is the air conditioner according to the first aspect or the second aspect, wherein the indoor fan is used during a period from the start of the reverse cycle defrost operation to the completion of the frost of the outdoor heat exchanger. , And fan stop defrosting for stopping the indoor fan can be selectively set.

  In this air conditioner, fan continuous defrosting and fan stop defrosting can be selectively set, so the state of the air conditioner can be changed according to demand when priority is given to performance and to prevention of cold air feeling. Can be changed.

  An air conditioner according to a fifth aspect of the present invention is the air conditioner according to the fourth aspect, wherein the operating frequency of the compressor at the time of continuous fan defrosting is lower than the operating frequency of the compressor at the time of fan stop defrosting. Is set to be bigger.

  In this air conditioner, the operating frequency of the compressor during fan-driven defrosting is set to be higher than the operating frequency of the compressor during fan-stopping defrosting, so the performance is significantly improved. On the other hand, even if the noise generated slightly by increasing the operating frequency of the compressor becomes loud, the noise generated by driving the indoor fan becomes inconspicuous, so that an unpleasant feeling can be prevented.

  In the air conditioner according to the first aspect of the present invention, the defrosting time can be reduced, and the startup performance at the time of return can be improved.

  In the air conditioner according to the second aspect of the present invention, reliable temporary driving of the indoor fan can be realized during the period from the start of the reverse cycle defrost operation to the completion of the frost of the outdoor heat exchanger.

  In the air conditioner according to the third aspect of the present invention, the operation that prioritizes time reduction can be performed over suppression of generation of noise when switching from the normal cycle to the reverse cycle, so that the defrosting time can be easily reduced.

  In the air conditioner according to the fourth aspect of the present invention, the convenience can be improved because the setting can be selected when giving priority to performance and when giving priority to prevention of a feeling of cold wind.

  In the air conditioner according to the fifth aspect of the present invention, performance can be improved without increasing discomfort.

The perspective view showing the appearance of the air conditioner concerning an embodiment. FIG. 1 is a circuit diagram illustrating an outline of a configuration of an air conditioner according to an embodiment. Sectional drawing cut | disconnected along the II line of FIG. 5 is a timing chart showing an outline of exchange of main signals between an outdoor unit and an indoor unit. (A) a timing chart related to the operating frequency of the compressor, (b) a timing chart related to the defrost request flag, (c) a timing chart related to the defrosting flag, (d) a timing chart related to the defrost completion preparation flag, and (e) the indoor space. A timing chart regarding a fan upper limit, (f) a timing chart regarding ON / OFF of a compressor, and (g) a timing chart regarding switching of a four-way switching valve. (A) a timing chart for switching the four-way switching valve, (b) a timing chart for ON / OFF of the outdoor fan, (c) a timing chart for the rotation speed of the indoor fan, and (d) an example of a temporal change in the temperature of the indoor heat exchanger. (E) a timing chart relating to the flap position, and (f) a graph showing an example of a change with time of the outdoor heat exchanger temperature. FIG. 7 is a partially cutaway perspective view for explaining the operation of the vertical flap.

(1) Outline of Configuration of Air Conditioner An outline of the configuration of an air conditioner according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. An air conditioner 1 shown in FIG. 1 includes an indoor unit 2 attached to a wall WL or the like in a room and an outdoor unit 3 installed outdoors. FIG. 2 is a circuit diagram of the air conditioner 1. The air conditioner 1 includes a refrigeration circuit 10 and can execute a vapor compression refrigeration cycle by circulating a refrigerant in the refrigeration circuit 10. The indoor unit 2 and the outdoor unit 3 are connected by a communication pipe 4 in order to circulate the refrigerant in the refrigeration circuit 10.

(1-1) Refrigeration circuit 10
The refrigeration circuit 10 includes a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, an expansion mechanism 14, an accumulator 15, and an indoor heat exchanger 16. The compressor 11 that sucks the refrigerant from the suction port and discharges the compressed refrigerant from the discharge port outputs the refrigerant discharged from the discharge port to the first port of the four-way switching valve 12.

  When the air-conditioning apparatus 1 performs the heating operation, the four-way switching valve 12 allows the refrigerant to flow between the first port and the fourth port, as shown by the broken line, and at the same time, the second port and the third port. Allow refrigerant to flow between ports. When the air conditioner 1 performs the cooling operation and performs the reverse cycle defrost operation, the four-way switching valve 12 circulates the refrigerant between the first port and the second port, as shown by the solid line. At the same time, the refrigerant flows between the third port and the fourth port.

  The outdoor heat exchanger 13 has a gas side inlet / outlet for mainly flowing the gas refrigerant to and from the second port of the four-way switching valve 12 and also allows the liquid refrigerant to mainly flow to the expansion mechanism 14. Liquid inlet / outlet for the The outdoor heat exchanger 13 causes heat to be exchanged between the refrigerant flowing through a heat transfer tube (not shown) connected between the liquid-side entrance and the gas-side entrance of the outdoor heat exchanger 13 and the outdoor air.

  The expansion mechanism 14 is disposed between the outdoor heat exchanger 13 and the indoor heat exchanger 16. The expansion mechanism 14 has a function of expanding the refrigerant flowing between the outdoor heat exchanger 13 and the indoor heat exchanger 16 to reduce the pressure.

  The indoor heat exchanger 16 has a liquid side inlet / outlet for flowing the liquid refrigerant with the expansion mechanism 14 and a gas side for flowing the gas refrigerant with the fourth port of the four-way switching valve 12. It has a doorway. The indoor heat exchanger 16 causes heat exchange between the refrigerant flowing through the heat transfer tube 16a (see FIG. 3) connected between the liquid-side entrance and the gas-side entrance and exit of the indoor heat exchanger 16 and the indoor air. .

  An accumulator 15 is arranged between the third port of the four-way switching valve 12 and the suction port of the compressor 11. In the accumulator 15, the refrigerant flowing from the third port of the four-way switching valve 12 to the compressor 11 is separated into a gas refrigerant and a liquid refrigerant. Then, gas refrigerant is mainly supplied from the accumulator 15 to the suction port of the compressor 11.

(1-2) Configuration other than Refrigeration Circuit 10 The outdoor unit 3 includes an outdoor fan 21 for generating an airflow of outdoor air passing through the outdoor heat exchanger 13. Further, the outdoor unit 3 includes an outdoor temperature sensor 22 for measuring the temperature of the outdoor air, and a temperature sensor 23 for the outdoor heat exchanger for measuring the temperature of the outdoor heat exchanger 13. Further, the outdoor unit 3 includes an outdoor controller 24 that controls the compressor 11, the four-way switching valve 12, the expansion mechanism 14, and the outdoor fan 21. The outdoor controller 24 includes, for example, a CPU (not shown) and a memory (not shown), and is configured to be able to control the outdoor unit 3 according to stored programs and the like. The outdoor controller 24 is connected to the outdoor temperature sensor 22 and the outdoor heat exchanger temperature sensor 23 in order to receive a signal regarding the temperature measured by the outdoor temperature sensor 22 and the outdoor heat exchanger temperature sensor 23. .

  The indoor unit 2 includes an indoor fan 31 for generating an airflow of indoor air passing through the indoor heat exchanger 16. Further, the indoor unit 2 includes an indoor temperature sensor 32 for measuring the temperature of the indoor air, and a temperature sensor 33 for the indoor heat exchanger for measuring the temperature of the indoor heat exchanger 16. Further, the indoor unit 2 includes an indoor control device 34 that controls the indoor fan 31. The indoor control device 34 includes, for example, a CPU (not shown) and a memory (not shown), and is configured to be able to control the outdoor unit 3 according to stored programs and the like. The indoor controller 34 is connected to the indoor temperature sensor 32 and the indoor heat exchanger temperature sensor 33 in order to receive a signal related to the temperature measured by the indoor temperature sensor 32 and the indoor heat exchanger temperature sensor 33. .

  The outdoor controller 24 and the indoor controller 34 are connected to each other by signal lines, and are configured to be able to transmit and receive signals to and from each other.

(1-3) Detailed Configuration of Indoor Unit 2 FIG. 3 shows a cross section of the indoor unit cut along line II in FIG. 1. The indoor unit 2 includes a casing 41, an indoor heat exchanger 16, an indoor fan 31, an air filter 42, a horizontal flap 43, and a vertical flap 49.

  An upper surface suction port 44 is provided on the upper surface of the casing 41. The indoor air near the upper surface suction port 44 is taken into the casing 41 from the upper surface suction port 44 by the driving of the indoor fan 31 and sent to the indoor heat exchanger 16 having an inverted V-shaped cross section. The dashed arrow A in FIG. 3 indicates the flow of indoor air sent from the upper surface suction port 44 to the indoor fan 31 via the indoor heat exchanger 16.

  On the lower surface of the casing 41, a lower surface suction port 45 and an air outlet 46 are formed. The lower surface suction port 45 is provided closer to the wall than the outlet port 46, and is connected to the inside of the casing 41 by a suction channel 47. From the lower surface suction port 45, room air near the lower surface suction port 45 is taken into the casing 41 by the driving of the indoor fan 31, and is sent to the indoor heat exchanger 16 through the suction channel 47. The dashed arrow B in FIG. 3 indicates the flow of room air sent from the lower surface suction port 45 to the indoor heat exchanger 16.

  The outlet 46 is provided on the front side of the indoor unit 2 with respect to the lower surface inlet 45, and is connected to the inside of the casing 41 by the outlet channel 48. The indoor air sucked from the upper surface suction port 44 and the lower surface suction port 45 is heat-exchanged by the indoor heat exchanger 16 and then blown out from the blowout port 46 into the room through the blowout channel 48. A dashed arrow C in FIG. 3 indicates a flow of air sent from the outlet channel 48 to the room via the outlet 46.

  Two horizontal flaps 43 are rotatably attached to the casing 41 near the outlet 46. The horizontal flap 43 is rotated by a flap driving motor (not shown), and opens and closes the air outlet 46 according to the operation state of the indoor unit 2. Further, the horizontal flap 43 has a function of changing the blowing direction of the room air up and down so that the room air blown out from the air outlet 46 is guided in a direction desired by the user. A vertical flap 49 is rotatably attached to the casing 41 near the outlet 46. The vertical flap 49 has a function of being rotated by a flap driving motor (not shown) to change the blowing direction of room air to the left and right.

(2) Outline of heating operation, cooling operation, and reverse cycle defrost operation (2-1) Heating operation When the air conditioner 1 is in the heating operation, the four-way switching valve 12 is set to the state shown by the broken line in FIG. Switch. That is, the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the indoor heat exchanger 16 via the four-way switching valve 12. At this time, the indoor heat exchanger 16 functions as a condenser. Therefore, as the refrigerant flows through the indoor heat exchanger 16, the refrigerant heats the indoor air by heat exchange with the indoor air, cools itself, condenses, and changes from a gas refrigerant to a liquid refrigerant. The low-temperature and high-pressure refrigerant deprived of the temperature by the indoor heat exchanger 16 is decompressed by the expansion mechanism 14 and changes to a low-temperature and low-pressure refrigerant. The refrigerant flowing into the outdoor heat exchanger 13 via the expansion mechanism 14 is warmed by heat exchange with outdoor air, evaporates, and changes from a liquid refrigerant to a gas refrigerant. At this time, the outdoor heat exchanger 13 functions as an evaporator. Then, a refrigerant mainly composed of a low-temperature gas refrigerant is sucked into the compressor 11 from the outdoor heat exchanger 13 via the four-way switching valve 12 and the accumulator 15. The normal cycle is such that the refrigerant flows through the compressor 11, the indoor heat exchanger 16, the expansion mechanism 14, and the outdoor heat exchanger 13 in this order, and the vapor compression refrigeration cycle is repeated.

(2-2) Cooling Operation During the cooling operation of the air conditioner 1, the four-way switching valve 12 switches to the state shown by the solid line in FIG. That is, the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor heat exchanger 13 via the four-way switching valve 12. At this time, the outdoor heat exchanger 13 functions as a condenser. Therefore, as the refrigerant flows through the outdoor heat exchanger 13, the refrigerant is cooled by heat exchange with the outdoor air, condenses, and changes from a gas refrigerant to a liquid refrigerant. The low-temperature and high-pressure refrigerant whose temperature has been deprived by the outdoor heat exchanger 13 is decompressed by the expansion mechanism 14 and changes to a low-temperature and low-pressure refrigerant. The refrigerant flowing into the indoor heat exchanger 16 via the expansion mechanism 14 cools the indoor air by heat exchange with the indoor air and is heated by itself, evaporates and changes from a liquid refrigerant to a gas refrigerant. At this time, the indoor heat exchanger 16 functions as an evaporator. Then, a refrigerant mainly composed of a low-temperature gas refrigerant is sucked into the compressor 11 from the indoor heat exchanger 16 via the four-way switching valve 12 and the accumulator 15.

(2-3) Reverse cycle defrost operation The reverse cycle defrost operation is performed to remove frost attached to the outdoor heat exchanger 13 due to the heating operation. Therefore, the operation is switched to the reverse cycle defrost operation in the middle of the heating operation, and when the reverse cycle defrost operation ends, the operation returns to the heating operation again. In the reverse cycle defrost operation, similarly to the cooling operation, the four-way switching valve 12 switches to the state shown by the solid line in FIG. In the reverse cycle defrost operation, the same vapor compression refrigeration cycle as in the cooling operation is repeated. That is, contrary to the normal cycle in the heating operation, the reverse cycle defrost operation is performed by flowing the refrigerant in the order of the compressor 11, the outdoor heat exchanger 13, the expansion mechanism 14, and the indoor heat exchanger 16 to compress the vapor. This is a reverse cycle that repeats a refrigeration cycle.

  When the reverse cycle defrost operation is started, as shown in FIG. 3, the outdoor unit 3 determines that the outdoor controller 24 performs defrosting while the heating control is being performed. When the outdoor unit 3 determines to perform defrost, a defrost request signal SG1 is transmitted from the outdoor control unit 24 of the outdoor unit 3 to the indoor control unit 34 of the indoor unit 2. When the indoor control device 34 receives the defrost request signal SG1, the indoor unit 2 starts preparations for the defrost operation. For example, when an electric heater for warming indoor air is additionally provided, the indoor control unit 34 turns off the electric heater (not shown) and then keeps the indoor fan 31 on for a while. Preparation for the defrosting operation is completed when is cooled.

  When the preparation for the defrosting operation of the indoor unit 2 is completed, the indoor control device 34 transmits a defrost permission signal SG2 to the outdoor control device 24. When receiving the defrost permission signal SG2, the outdoor controller 24 starts defrost control, and transmits a signal SG3 indicating that defrost is being performed to the indoor controller 34.

  When the outdoor unit 24 determines that the defrosting is completed in the outdoor unit 3, the outdoor control unit 24 notifies the indoor control unit 34 of the indoor unit 2 of the return to the normal heating operation from the outdoor control unit 24 to the normal notification signal SG4. Is sent. The indoor unit 2 that has received the normal notification signal SG4 returns to the heating control for the heating operation.

(3) Operation during reverse cycle defrost operation The operation of the air conditioner 1 during reverse cycle defrost operation is shown in FIGS. 5 (a) to 5 (g) and FIGS. 6 (a) to 6 (f). This will be described with reference to the timing chart shown in FIG. In order to make the relationship between these timing charts easy to understand, the operation of the four-way switching valve is shown in both drawings (see FIGS. 5 (g) and 6 (a)).

  Since the defrost request flag is a flag indicating transmission of a defrost request by the outdoor control device 24, in the chart of the defrost request flag shown in FIG. From 1 to 1, indicating that the defrost request signal SG1 was transmitted at time t1. At time t1, as shown in FIG. 5 (e), the upper limit of the number of revolutions of the indoor fan 31 in the indoor unit 2 that has received the defrost request signal SG1 is limited to the limit during normal heating operation. Is switched to the limit for defrosting. Further, in the outdoor unit 3, the outdoor controller 24 starts control to gradually lower the operating frequency of the compressor 11 from time t1.

  Since the flag indicating that the defrosting is being performed is a flag indicating that the outdoor controller 24 is performing the defrosting, the timing chart (see FIG. 5C) indicating the flag indicating that the defrosting is being performed changes from 0 to 1 at time t2. It can be seen that the signal SG3 indicating that defrosting is being performed has been transmitted from the outdoor unit 3. Conventionally, the compressor 11 was turned off at the time t2. However, according to a timing chart showing ON / OFF of the compressor 11 (see FIG. 5F), the compressor 11 is turned on at the time t2. You can see that it is maintained. Since the compressor 11 is turned off and the operating frequency of the compressor 11 does not become 0 (see FIG. 5A), the four-way switching valve 12 on the side of the indoor heat exchanger 16 and the side of the outdoor heat exchanger 13 are closed. The pressure does not become the same, and a pressure difference remains between the indoor heat exchanger 16 side of the four-way switching valve 12 and the outdoor heat exchanger 13 side.

  As shown in FIG. 5 (g), at a time t3, the operating frequency of the compressor 11 is reduced to a pressure difference at which the four-way switching valve 12 can be switched, but the pressure difference remains. , The four-way switching valve 12 is switched from the heating side to the cooling side. That is, the connection state of the broken line in FIG. 2 is switched to the connection state of the solid line. When the four-way switching valve 12 is switched, the compressor 11 thereafter starts increasing the operating frequency (after time t5).

  The indoor fan 31 is stopped at a time t4 a little after the time t3 when the four-way switching valve 12 is switched. In order to perform such control, the indoor side control device 34 starts counting by a built-in timer at the timing when the defrosting flag changes from 0 to 1. Then, the indoor side control device 34 delays the stop timing of the indoor fan 31 by a first predetermined time so that the indoor fan 31 can be stopped at time t4 (see FIG. 6C).

  Further, the outdoor fan 21 is also stopped at a time t6, slightly after the stop of the indoor fan 31. In order to perform such control, the outdoor controller 24 starts counting by a built-in timer at the timing when the defrosting flag changes from 0 to 1. Then, the outdoor controller 24 delays the stop timing of the outdoor fan 21 so that the outdoor fan 21 can be stopped at time t6.

(3-1) Transition of the wind direction adjusting blade to the blown air diffusion state The indoor side control device 34 counts the time elapsed by the timer from the time t4 when the indoor fan 31 stops, and the time when the second predetermined time has elapsed. At t7, the movement is started so that the wind direction adjusting blade is in the blown air diffusion state. Specifically, the movement of the horizontal flap 43 and the vertical flap 49, which are the wind direction adjusting blades, is started, and the airflow blown out by the horizontal flap 43 is directed horizontally or upward from the horizontal. The air is moved so that the air flow spreads out. Preferably, the transition to the blown air diffusion state is completed before the next indoor fan 31 is driven (see FIG. 6E).

  In the blown air diffusion state, as shown in FIG. 3, the horizontal flap 43 is in an upward blowing state, and the airflow blown out by the horizontal flap 43 is horizontal or goes upward. Further, in the blown air diffusion state, as shown in FIG. 7, the horizontal flap 43x located on the right side of the longitudinal center of the casing 41 tilts to the right, and is located on the left side of the longitudinal center of the casing 41. The horizontal flap 43y tilts to the left.

(3-2) First Drive of Indoor Fan As shown in FIG. 6F, the temperature of the outdoor heat exchanger 13 measured by the outdoor heat exchanger temperature sensor 23 is determined by the operating frequency of the compressor 11. When the temperature of the outdoor heat exchanger gradually increases after time t2 when the defrosting control starts and at time t2 when the defrost control starts, and the frost attached to the outdoor heat exchanger 13 starts to melt, almost zero. Constant at ° C. The outdoor controller 24 monitoring the measured value of the outdoor heat exchanger temperature sensor 23 drives the indoor fan 31 when the temperature of the outdoor heat exchanger 13 reaches 0 ° C. (time t7) (FIG. 6 (c)). If the indoor fan 31 is not driven, the temperature of the indoor heat exchanger 16 continues to decrease as shown by the two-dot chain line in FIG. However, when the indoor fan 31 is driven, heat exchange occurs between the warm indoor air and the refrigerant, so that the temperature of the indoor heat exchanger 16 gradually increases. When the temperature of the indoor heat exchanger 16 gradually increases, in other words, the temperature of the refrigerant gradually increases. The timing at which the indoor fan 31 is driven is preferably set after the horizontal flap 43 and the vertical flap 49 have shifted to the blown air diffusion state. When the indoor fan 31 is driven, the horizontal flap 43 is already in the upper blowing state, and the vertical flap 49 is in a state of expanding the airflow to the left and right. When the cool air reaches the user located at a position lower than the indoor unit 2 even when the cool air is blown out, the cool air is diffused and mixed with the indoor air, so that the user does not easily feel the blow of the cool air. During the reverse cycle defrost operation, the horizontal flap 43 and the vertical flap 49 maintain the blown air diffusion state.

  At the same time as when the indoor fan 31 starts driving from time t7, the indoor control device 34 starts counting by the timer. The indoor control device 34 drives the indoor fan 31 for the third predetermined time, and stops the indoor fan 31 at time t8 (see FIG. 6C). The third predetermined time is set to an appropriate value within a range from several seconds to several tens of seconds, for example. The rotation speed of the indoor fan 31 from time t7 to time t8 is set as low as possible. Specifically, it is set to a rotation speed at which the settable fan air volume of the indoor fan 31 driven during the normal heating operation is minimized. Alternatively, it is configured such that the fan airflow can be set for the reverse cycle defrost operation separately from the control of the indoor fan 31 during the heating operation, and the fan airflow of the indoor fan 31 is driven during the normal heating operation. The fan air volume may be set to be smaller than the lowest fan air volume that can be set for the indoor fan 31 that is present.

(3-3) Second Drive of Indoor Fan The indoor control device 34 counts with a timer from time t8 when the indoor fan 31 stops, and monitors the elapse of the third predetermined time. The third predetermined time is a time sufficient for the cold air blown by the first drive of the indoor fan 31 to diffuse, and is an appropriate time within a range from several seconds to several tens of seconds. At the point in time when the third predetermined time has elapsed (time t9 in FIG. 6C), the indoor side control device 34 starts the second drive of the indoor fan 31.

  When the reverse cycle defrost operation continues and the attached frost does not melt and disappears, the temperature of the outdoor heat exchanger 13 starts to increase again (see FIG. 6 (f)). Since the temperature of the outdoor heat exchanger 13 starts increasing at the time t10, the outdoor controller 24 transmits information on the start of the outdoor heat exchanger temperature increase to the indoor controller 34. The indoor control device 34 receives the information on the rise in the outdoor heat exchanger temperature and stops driving the indoor fan 31.

  However, the indoor side control device 34 starts counting by the built-in timer from the time of starting the driving of the indoor fan 31 for the second time, and stops driving the indoor fan 31 when a fourth predetermined time has elapsed from time t9. . Therefore, if the elapse of the fourth predetermined time is earlier than the start of the temperature rise of the outdoor heat exchanger, the driving of the indoor fan 31 is stopped before the time t10.

  If the indoor fan 31 is not driven for the second time, the temperature of the indoor heat exchanger 16 is reduced from the time when the first drive of the indoor fan 31 is stopped, as shown by the two-dot chain line in FIG. Although the temperature continues to decrease, the second drive of the indoor fan 31 also causes heat exchange between the warm indoor air and the refrigerant, so that the temperature of the indoor heat exchanger 16 gradually increases.

(3-4) End of Reverse Cycle Defrost Operation The outdoor controller 24 counts with a timer from time t5 at which the compressor 11 starts operating, and determines whether a fifth predetermined time has elapsed. The fifth predetermined time is a time sufficient to prevent the reverse cycle defrost operation from being released in an insufficient state. Then, after the fifth predetermined time has elapsed, the outdoor controller 24 starts the defrosting release determination. Then, when the temperature of the outdoor heat exchanger 13 reaches the first set temperature Ta ° C., the outdoor controller 24 determines the defrost release to stop the reverse cycle defrost operation (time t11).

  When the defrost release is determined, the operating frequency of the compressor 11 is changed to the operating frequency, and a defrost release preparation signal for starting preparation for defrost release is transmitted to the indoor control device 34 (FIG. 5 (d). )reference). Note that the operating frequency is not a constant value, but is appropriately changed at each timing. The indoor control device 34 that has received the defrost release preparation signal starts counting the time elapsed from the time t11 by using a built-in counter, and monitors the elapse of the sixth predetermined time. At a time t12 when a sixth predetermined time has elapsed from the time t11, the outdoor controller 24 ends the defrost release preparation and stops the compressor 11 (see FIG. 5 (f)).

  The outdoor controller 24 switches the four-way switching valve 12 at a time t13 when a seventh predetermined time has elapsed since the compressor 11 was stopped (see FIG. 5G). At the time t13, the upper limit of the indoor fan 31 is returned from the defrosting operation to the normal state (see FIG. 5E). By the time t13, the horizontal flap 43 and the vertical flap 49 are returned to the normal state from the position where the defrosting is being performed, that is, the blown air diffusion state (see FIG. 6E). At this time t13, the outdoor controller 24 starts driving the outdoor fan 21 (see FIG. 6B).

  At time t14, which is slightly delayed from time t13, the normal notification signal SG4 is transmitted from the outdoor controller 24 to the indoor controller 34 (see FIG. 5B). Then, the indoor control device 34 controls the indoor fan 31 to start driving from time t14 in accordance with the heating operation.

(3-5) Selection of fan defrosting and fan-driven defrosting As shown in FIG. 1, the air conditioner 1 is configured so that various settings can be made using the remote controller 5. The air conditioner 1 is configured such that fan stop defrost and fan drive defrost can be selectively set using the remote controller 5.

  The fan-driven defrosting is a defrosting method for driving the indoor fan 31 during the time from the time t7 to the time t8 and the time t9 to the time t10 during the reverse cycle defrosting operation, and the fan stop defrosting is performed during the reverse cycle defrosting operation. This is a defrosting method in which the driving of the indoor fan 31 between time t7 and time t8 and between time t9 and time t10 is stopped. The operating frequency of the compressor 11 at the time of fan-driven defrosting is shown by a solid line near time t7 to time t8 and time t9 to time t10 in FIG. 5A, the operating frequency of the compressor 11 at the time of the fan stop defrosting is shown near the time t7 to the time t8 and near the time t9 to the time t10. As can be seen by comparing the solid line and the dashed line in FIG. 5A, the operating frequency of the compressor 11 at the time of fan-driven defrosting is set to be higher than the operating frequency at the time of fan-stopping defrosting. I have.

(4) Features (4-1)
As described above, in the air conditioner 1, during the period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted, the indoor fan 31 is temporarily stopped during the period from the time t7 to the time t8. Driven between time t9 and time t10, the indoor heat exchanger 16 promotes heat exchange between warm indoor air in the room and a refrigerant that has been deprived of heat during defrosting and has become cooler. Can be. Since the temperature of the refrigerant can be raised by the temporary drive of the indoor fan 13, the defrosting time can be shortened and the startup performance at the time of return can be improved.

(4-2)
In the above-described air conditioner 1, the period from the time when the temperature sensor for the outdoor heat exchanger detects a constant temperature near 0 ° C. to the time when the temperature detected by the temperature sensor for the outdoor heat exchanger 23 starts to rise (from time t7) (Until time t10) is detected by the outdoor heat exchanger temperature sensor 23, so that the period from the start of the reverse cycle defrost operation to the complete frost melting of the outdoor heat exchanger 13 is reliably detected with a simple configuration. can do. During the period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger 13 is completely melted, the reliable temporary driving of the indoor fan 31 can be realized.

(4-3)
In the above-described air conditioner 1, since the indoor fan 31 is continuously driven from the time t2 to the time t4, that is, for a predetermined time from the start of the reverse cycle defrost operation, when the normal cycle is switched to the reverse cycle. Also, since the indoor fan 31 is rotating, the influence of the sound generated by the four-way switching valve 12 at the time of switching (time t3) of the four-way switching valve 12 that switches from the normal cycle to the reverse cycle can be suppressed. When switching from the normal cycle to the reverse cycle, the compressor 11 is switched without stopping, and the compressor 11 is not stopped, thereby shortening the time required from the stop state at the time of switching to raising the operating frequency. Can be. As a result, the operation that prioritizes time reduction can be performed over suppression of generation of noise in the four-way switching valve 12 when switching from the normal cycle to the reverse cycle, so that the defrosting time can be easily reduced.

(4-4)
In the air conditioner 1 described above, the fan drive defrost and the fan stop defrost can be selectively set. Therefore, when the performance is to be prioritized and when the prevention of the feeling of cold air is to be prioritized, for example, a remote controller 5, the state of the air conditioner 1 can be changed. As a result, when the user wants to give priority to the performance and when the user wants to give priority to the prevention of the sensation of the cool wind, for example, the setting can be selected using the remote controller 5, so that the convenience for the user is improved.

(4-5)
In the above-described air conditioner 1, since the operating frequency of the compressor 11 at the time of the fan-driven defrost is set to be higher than the operating frequency of the compressor 11 at the time of the fan-stopped defrost, the fan-driven defrosting is performed. The improvement in performance during frost becomes remarkable. In addition, even if the refrigerant flow noise generated in the indoor heat exchanger 16 is slightly increased by increasing the operating frequency of the compressor 11, the refrigerant flow noise becomes less noticeable due to the driving of the indoor fan 31 so as not to give an unpleasant feeling. Can be As described above, if the fan driving station layer is selected, the performance can be improved without increasing discomfort.

(5) Modification (5-1) Modification A
In the above-described embodiment, a case has been described in which the first drive of the indoor fan 31 and the second drive of the indoor fan 31 are performed during the reverse cycle defrost operation. It is also possible to configure an air conditioner in which one is omitted.

(5-2) Modification B
In the above embodiment, the case where the first drive of the indoor fan 31 and the second drive of the indoor fan 31 are performed during the reverse cycle defrost operation has been described. The air conditioner may be configured such that the indoor fan 31 is driven.

(5-3) Modification C
In the above-described embodiment, the case where the driving of the indoor fan 31 is stopped from the time t7 to the time t8 and the time t9 to the time t10 in the fan stop defrost has been described. One of the driving of the indoor fan 31 from t9 to time t10 may be stopped.

(5-4) Modification D
In the above embodiment, the case where the driving of the indoor fan 31 is stopped during the period from time t4 to time t7 has been described. However, the indoor fan 31 may be driven during the period from time t4 to time t7. . In the case of such a configuration, it is preferable that an upper limit suitable for the reverse cycle defrost operation is provided for the rotation speed of the indoor fan 31 during a period from time t4 to time t7.

REFERENCE SIGNS LIST 1 air conditioner 2 indoor unit 3 outdoor unit 10 refrigeration circuit 11 compressor 12 four-way switching valve 13 outdoor heat exchanger 14 expansion mechanism 16 indoor heat exchanger 21 outdoor fan 23 outdoor heat exchanger temperature sensor 24 outdoor control device 31 Indoor fan 33 Temperature sensor 34 for indoor heat exchanger Indoor control device

JP 2007-155261 A JP 2013-130341 A

Claims (4)

A normal cycle in which a refrigerant flows in the order of a compressor (11), an indoor heat exchanger (16), an expansion mechanism (14), and an outdoor heat exchanger (13) to repeat a vapor compression refrigeration cycle, the compressor, and the outdoor heat A refrigeration circuit (10) capable of switching between a reverse cycle in which a refrigerant flows in the order of the exchanger, the expansion mechanism, and the indoor heat exchanger to repeat a vapor compression refrigeration cycle;
An indoor fan (31) for generating an airflow of indoor air in the indoor heat exchanger;
An outdoor heat exchanger temperature sensor (23) for measuring an outdoor heat exchanger temperature of the outdoor heat exchanger ,
In a reverse cycle defrost operation in which a refrigerant flows through the refrigeration circuit in the reverse cycle to defrost the outdoor heat exchanger, the temperature sensor for the outdoor heat exchanger detected by the temperature sensor for the outdoor heat exchanger is close to 0 ° C. The period from when the constant temperature is detected to when the temperature detected by the outdoor heat exchanger temperature sensor starts to rise, from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted. An air conditioner that detects a period and temporarily drives the indoor fan during a period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted. Driving the indoor fan continuously for a predetermined time from the start of the reverse cycle defrost operation,
The air conditioner according to claim 1 . During the period from the start of the reverse cycle defrost operation to the time when the frost of the outdoor heat exchanger is completely melted, the fan continuous defrosting for driving the indoor fan and the fan stop defrosting for stopping the indoor fan are selectively set. Is configured so that
The air conditioner according to claim 1 . The operating frequency of the compressor at the time of the fan continuous defrost is set to be higher than the operating frequency of the compressor at the time of the fan stop defrost,
The air conditioner according to claim 3 .

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