JP4990221B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly, to an air conditioner that simultaneously performs defrosting of an outdoor heat exchanger and heating of a room.

  When the air heat source heat pump air conditioner is operated for heating, the outdoor heat exchanger forms frost if the humidity of the outdoor air is high. When frost formation occurs, the ventilation path of the outdoor heat exchanger is narrowed, so that the amount of outdoor air circulating through the outdoor heat exchanger is reduced. When the amount of circulating outdoor air decreases, the amount of heat exchange decreases, and accordingly, the evaporation temperature of the refrigerant flowing in the outdoor heat exchanger decreases. When the evaporation temperature of the refrigerant decreases, the surface temperature on the outside of the outdoor heat exchanger also decreases, and frost formation tends to occur more and more. In this state, the amount of heat pumped from the outdoor air by the outdoor heat exchanger decreases, and the amount of heat that can be dissipated from the indoor heat exchanger also decreases. Therefore, the heating capacity also decreases and indoor comfort is impaired. In order to prevent this, when the amount of frost formation on the outdoor heat exchanger exceeds a predetermined amount, the frost of the outdoor heat exchanger is melted by defrosting operation and allowed to flow down and discharged outside the apparatus.

  There is a reverse cycle defrosting method as a widely known defrosting method. When defrosting is required during heating operation, the refrigeration cycle is switched to the cooling cycle, the compressor is used as a heat source, the indoor unit is used as an evaporator, and the high-temperature gas refrigerant from the compressor is used as outdoor heat. It flows through the exchanger and defrosts with sensible heat and latent heat of condensation of the refrigerant.

  Moreover, as a conventional example of an air conditioner that performs defrosting of an outdoor heat exchanger while performing heating operation indoors, for example, the techniques disclosed in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4 are known. It has been. These conventional examples are introduced below.

  In Patent Document 1, in a heat pump air conditioner that heats a room by using an outdoor heat exchanger as an evaporator and an indoor heat exchanger as a condenser during heating operation, the outdoor heat exchanger is divided into a plurality of parts in the vertical direction. The divided outdoor heat exchangers are connected to the indoor heat exchanger in parallel, connected to the inlet side of the compressor via two-way valves, and the outlet side of the compressor is branched. When each pipe is connected to each outdoor heat exchanger via a two-way valve and defrosting is performed during heating operation, a part of the discharge gas from the compressor is divided into each divided outdoor heat exchanger from the upper side. It is disclosed that heating and gradual frosting are performed in parallel by sequentially switching to the lower side.

  Patent Document 2 discloses an outdoor heat exchange in an air conditioner in which a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger are connected by a refrigerant pipe to form a refrigeration cycle. The compressor is separated into two rows before and after the air flow generated by the rotation of the outdoor blower and connected in parallel to each other, and the discharge side piping of the compressor and the heating of both outdoor heat exchangers It is disclosed that a bypass passage having an on-off valve is provided between the hour inlet side pipe and a high capacity heating operation, a low capacity heating operation, a simultaneous operation of defrosting and heating, and the like are performed.

  In Patent Document 3, an outdoor heat exchanger formed by connecting a plurality of divided heat exchangers in parallel, and a compressor, a four-way valve, an indoor heat exchanger, and a pressure reducing device are connected to the outdoor heat exchanger. A refrigeration cycle configured to be connected and capable of heating operation, a bypass path for guiding the discharge gas discharged from the compressor to the inlet portion of each heat exchanger during heating operation of the outdoor heat exchanger, and this Opening / closing means for opening / closing each outlet of the bypass passage, detection means for detecting frost formation on each heat exchanger of the outdoor heat exchanger, and compressor for controlling the opening / closing means according to the detection result of frost formation during heating operation And a means for causing the discharge gas from the refrigerant to flow into a frosted heat exchanger.

In Patent Document 4, a compressor, a four-way valve for switching a flow path, two outdoor heat exchangers connected in parallel, a pressure reducing device capable of switching between cooling and heating, and an indoor heat exchanger are sequentially piped and refrigerated. In an air conditioner refrigeration system that constitutes a cycle, a cooling / heating decompressor is connected in series with two outdoor heat exchangers, and two bypass pipes each provided with an on-off valve are branched from the discharge side of the compressor. These two bypass pipes are connected to two connecting pipes that connect between the outdoor heat exchanger and the cooling / heating decompressor, and the open / close valves provided in each bypass pipe are alternately opened and closed during the defrosting operation. Then, it is disclosed that two outdoor heat exchangers are alternately defrosted.
JP 09-318206 A JP 2001-059664 A Japanese Patent Laid-Open No. 04-110576 JP 2002-188873 A

  When starting the heating operation when the outside air temperature is low such as in the early morning of winter, it is necessary to start defrosting before the room temperature reaches the set temperature. In the conventionally known reverse cycle defrosting type air conditioner, Since the heating operation is stopped and the reverse cycle defrosting operation is started, there is a problem that the room temperature greatly decreases during the defrosting and the comfort is impaired, and the time until the room temperature reaches the set temperature is increased. .

  In the air conditioner of Patent Document 1, since defrosting is always performed during heating operation, there is a problem that indoor heating is performed in a state where the heating capacity is constantly reduced. Moreover, since the defrosting of the minimum part of the outdoor heat exchanger divided into three is performed by sequentially switching, there is a problem that the defrosting time becomes long.

  In the air conditioners of Patent Literature 2 and Patent Literature 3, since the outdoor heat exchanger is separated into two front and rear rows with respect to the air flow and alternately defrosted, one of the separated outdoor heat exchangers There was a problem that the melted water generated by defrosting could not be used for melting the other frost and could not be efficiently defrosted in a short time.

  In the air conditioner of Patent Document 4, since the outdoor heat exchanger is separated into the left and right with respect to the air flow and alternately defrosted, melting caused by one defrosting in the separated outdoor heat exchanger There was a problem that water could not be used for melting the other frost and could not be efficiently defrosted in a short time.

  The purpose of the present invention is to perform defrosting simultaneously with heating to ensure indoor comfort and to shorten the defrosting time, and when a significant difference occurs in the frosting amount of the heat exchanger. Is to provide an air conditioner having a heat exchanger divided into a plurality of parts so that defrosting can be performed by limiting only the relevant part.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger are connected by a refrigerant pipe to form a refrigeration cycle, and the outdoor heat exchanger is divided into a plurality of units and connected in parallel. Corresponding to the refrigerant circuit of each outdoor heat exchanger, a main circuit on-off valve is provided on the inlet side during heating operation, and the discharge side of the compressor and the inlet side during heating operation of the refrigerant circuit of each outdoor heat exchanger are provided. A control device for providing a hot gas bypass circuit to be connected, providing a bypass on-off valve corresponding to the refrigerant circuit of each outdoor heat exchanger in the hot gas bypass circuit, and controlling each component of the on-off valve and the refrigeration cycle An air conditioner provided with
When starting defrosting of the outdoor heat exchanger during heating operation, the control device controls opening and closing of the main circuit on-off valve and a part of the bypass on-off valve, and among the plurality of outdoor heat exchangers A defrosting / heating operation is performed in which a part is defrosted and heated by another outdoor heat exchanger, and the defrosting / heating operation is sequentially repeated for all of the plurality of outdoor heat exchangers, and then the heating operation is resumed. To control and
Further, the control device detects and determines an outdoor heat exchanger with a large amount of frost formation in the plurality of outdoor heat exchangers after the defrosting / heating operation is finished, and the corresponding outdoor heat exchanger The open / close control of the main circuit on / off valve and the bypass on / off valve corresponding to the above is performed, and limited defrosting / heating operation is performed in which only the plurality of the corresponding outdoor heat exchangers are defrosted and heated by other outdoor heat exchangers. After that, control is made to return to the heating operation.

  In the air conditioner, the control device monitors the refrigerant temperatures of the outdoor heat exchangers and makes a determination based on the refrigerant temperatures when shifting to the limited defrosting / heating operation. It is assumed that the transition control is performed. Further, the control device, as a determination of the transition to the limited defrosting and heating operation, the minimum value of the refrigerant temperature of each outdoor heat exchanger is less than 0 ℃, and the refrigerant temperature has become the minimum value When the difference between the average value of the refrigerant temperature of the other outdoor heat exchangers other than the outdoor heat exchanger and the minimum value of the refrigerant temperature exceeds 5 ° C., control is performed so as to shift to the limited defrosting / heating operation. The configuration.

  ADVANTAGE OF THE INVENTION According to this invention, defrosting time can be shortened, ensuring indoor comfort by the defrost and heating operation which performs defrost and heating simultaneously.

  Moreover, when the difference in the frost amount of the heat exchanger of the refrigerant circuit divided into a plurality becomes remarkable and it is necessary to defrost only by limiting the heat exchanger of the refrigerant circuit having a large amount of frost, the limited defrost -Defrosting time can be further shortened while ensuring indoor comfort by heating operation.

  An air conditioner according to an embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the refrigeration cycle of the air conditioner according to the present embodiment.

  1 and 2, the air conditioner 1 includes a refrigeration cycle, a blower, and a control system that controls them. The illustrated air conditioner 1 is a separate type air conditioner in which an indoor unit 2 and an outdoor unit 6 are connected via a refrigerant pipe 8, electrical wiring, signal wiring, and the like.

  The refrigeration cycle includes a compressor 75, a four-way valve 72, an outdoor heat exchanger 73, main circuit on-off valves 713a, 713b, 713c, 713d, a pressure reducing device 74, a hot pipe 713e, an indoor heat exchanger 33, and bypass on-off valves 715a, 715b. , 715c, 715d, and these are connected through a refrigerant pipe. The refrigerant pipes are a suction pipe 710, a discharge pipe 711, a use side gas pipe 712, a liquid pipe 713, a heat source side gas pipe 714, a hot gas bypass pipe 715, a hot pipe 713e, a main circuit / bypass common pipe 716a, 716b, 716c, 716d, etc.

  The indoor heat exchanger 33 is accommodated in the indoor unit 2, and also includes a compressor 75, a four-way valve 72, an outdoor heat exchanger 73, main circuit on / off valves 713a, 713b, 713c, 713d, a decompression device 74, and a hot pipe 713e. The bypass opening / closing valves 715a, 715b, 715c, and 715d are accommodated in the outdoor unit 6.

  The four-way valve 72 is an example of a refrigerant flow path switching valve. The four-way valve 72 switches between a cooling cycle and a heating cycle. Here, the cooling cycle is a cycle in which the refrigerant discharged from the compressor 75 via the discharge pipe 711 is guided to the outdoor heat exchanger 73 and the refrigerant from the indoor heat exchanger 33 is returned to the compressor 75. The heating cycle is a cycle in which the refrigerant discharged from the compressor 75 is guided to the indoor heat exchanger 33 and the refrigerant from the outdoor heat exchanger 73 is returned to the compressor 75 via the suction pipe 710 and the accumulator 76.

  Accordingly, the outdoor heat exchanger 73 constitutes a high-pressure side heat exchanger (condenser) during the cooling operation of the cooling cycle, and constitutes a low-pressure side heat exchanger (evaporator) during the heating operation of the heating cycle. The indoor heat exchanger 33 constitutes a high-pressure side heat exchanger (condenser) during the heating operation of the heating cycle, and constitutes a low-pressure side heat exchanger (evaporator) during the cooling operation of the cooling cycle.

  The outdoor heat exchanger 73 includes a refrigerant pipe and heat exchange fins, and a refrigerant circuit formed by the refrigerant pipe is divided into a plurality of pieces and connected in parallel. This refrigerant circuit is divided into a plurality of parts. The outdoor heat exchanger 73 includes a first heat exchanger 731, a second heat exchanger 732, a third heat exchanger 733, and a fourth heat exchanger 734. The configuration of the outdoor heat exchanger of the refrigerant circuit divided into a plurality may be a structure in which each is separated (a structure in which the first to fourth heat exchangers are independent) or an integrated structure.

  Each of the outdoor heat exchangers 731, 732, 733, and 734 is connected to the decompression device 74 via main circuit on-off valves 713a, 713b, 713c, and 713d. Further, the heat exchangers 731, 732, 733, and 734 and the main circuit on / off valves 713a, 713b, 713c, and 713d are branched from each other, and the discharge pipes of the compressor 75 are connected via the bypass on / off valves 715a, 715b, 715c, and 715d. 711 is provided with a hot gas bypass circuit connected by a hot gas bypass pipe 715.

  The decompression device 74 is provided between the outdoor heat exchanger 73 and the indoor heat exchanger 33, depressurizes the refrigerant from the outdoor heat exchanger 73 during cooling of the cooling cycle, and the indoor heat exchanger during heating operation of the heating cycle. The refrigerant from 33 is depressurized. Here, in the present embodiment, the decompression device 74 is configured by an expansion valve whose throttle opening is controllable, for example, an electric type.

  The main circuit on / off valves 713a, 713b, 713c, and 713d and the bypass on / off valves 715a, 715b, 715c, and 715d are composed of electromagnetic on / off valves, and open and close the refrigerant main circuit and the hot gas bypass circuit.

  The air blower in the air conditioner 1 includes an outdoor air blower 63 accommodated in the outdoor unit 6 and an indoor air blower 31 accommodated in the indoor unit 2. The outdoor blower includes an outdoor fan 631 that causes outdoor air to flow through the outdoor heat exchanger 73 and an outdoor blower motor 633 that drives the outdoor fan 631. The indoor air blower includes an indoor fan 311 that causes indoor air to flow through the indoor heat exchanger 33, and an indoor air blower motor 313 that drives the indoor fan 311. In the present embodiment, an axial fan is used as the outdoor fan 631 and a cross fan is used as the indoor fan 311.

  The control system in the air conditioner 1 includes refrigerant temperature detection sensors 811a, 811b, 811c, 811d, and 812 and a control device 10. Refrigerant temperature detection sensors 811a, 811b, 811c, 811d, and 812 are refrigerant temperature detection sensors 811a, 811b, 811c that detect the outlet temperatures of the heat exchangers 731, 732, 733, and 734 of the outdoor heat exchanger 73 during heating. 811d and the refrigerant | coolant temperature detection sensor 812 which detects the exit | outlet temperature of the outdoor heat exchanger 73 at the time of reverse cycle defrosting.

  Based on the detection results of the refrigerant temperature detection sensors 811a, 811b, 811c, 811d, and 812 and the user's operation command, the control device 10 includes a compressor 75, a four-way valve 72, an outdoor fan motor 633, an indoor fan motor 313, a reduced pressure The device 74, main circuit on / off valves 713a, 713b, 713c, 713d, bypass on / off valves 715a, 715b, 715c, 715d, and the like are controlled. Here, in the present embodiment, the control device 10 is shown as a single control device having a function of calculating and a control device having a function of controlling each device, but these are configured separately. Alternatively, a control device having a function of controlling each device may be further divided.

  Next, cooling and heating operation operations in the air conditioner according to the embodiment of the present invention will be described below with reference to FIGS. 3 and 4. FIG. 3 is a refrigeration cycle diagram showing the refrigerant flow during the cooling operation of the air conditioner according to the present embodiment. FIG. 4 is a refrigeration cycle diagram showing the refrigerant flow during the heating operation of the air conditioner according to the present embodiment.

  First, the cooling operation in the cooling cycle will be described with reference to FIG. When the air conditioner 1 is cooled, the four-way valve 72 is switched as shown in FIG. 3, the main circuit on / off valves 713a, 713b, 713c, 713d are opened, and the bypass on / off valves 715a, 715b, 715c, 715d are closed. Thus, the cooling operation cycle is formed, and the compressor 75, the outdoor air blowing motor 633, and the indoor air blowing motor 313 are operated.

  The gas refrigerant sucked into the compressor 75 is compressed by the compressor 75, becomes a high-temperature and high-pressure gas refrigerant, flows in the direction of the solid line arrow in FIG. Enters the heat exchangers 731, 732, 733, 734 of the heat exchanger 73, is cooled and condensed by heat exchange with the outdoor air, and becomes a refrigerant of liquid or gas-liquid mixture.

  Next, the refrigerant enters the decompression device 74 via the main circuit on-off valves 713a, 713b, 713c, and 713d, expands due to decompression, and becomes a low-pressure gas-liquid mixed refrigerant. This gas-liquid mixed refrigerant flows in the direction of the broken-line arrow indicating the flow of the low-pressure refrigerant in FIG. 3, passes through the hot pipe 713e, exits the outdoor unit 6 and enters the indoor unit 2, and the indoor heat serving as an evaporator It enters the exchanger 33 and exchanges heat with room air to cool the room. It is heated and returns to the compressor 75 as a gas refrigerant.

  Next, the heating operation in the heating cycle will be described with reference to FIG. In FIG. 4, when the heating operation is performed, the four-way valve 72 is switched as shown in FIG. 4, the main circuit on / off valves 713a, 713b, 713c, 713d are opened, and the bypass on / off valves 715a, 715b, 715c, 715d are closed. While forming a heating operation cycle, the compressor 75, the outdoor air blowing motor 633, and the indoor air blowing motor 313 are operated.

  The gas refrigerant sucked into the compressor 75 is compressed by the compressor 75, becomes a high-temperature and high-pressure gas refrigerant, flows in the direction of the solid line arrow in FIG. It enters into the vessel 33, is cooled and condensed by exchanging heat with room air, and becomes a refrigerant of liquid or gas-liquid mixture.

  The refrigerant that has condensed and entered the liquid or gas-liquid mixture exits the indoor unit 2 and enters the outdoor unit 6, and the hot pipe 713 e routed near the lower portion of the outdoor heat exchanger 73 or near the defrost water discharge port. The ice pieces dropped during defrosting are melted and completely discharged out of the outdoor unit 6 so that no residual frost is generated in the outdoor unit 6. The refrigerant passing through the hot pipe 713e enters the decompression device 74, expands due to decompression, and becomes a low-pressure gas-liquid mixed refrigerant. This gas-liquid mixed refrigerant flows in the direction of the broken arrow indicating the flow of the low-pressure refrigerant in FIG. 4, and the heat of the outdoor heat exchanger 73 serving as an evaporator is passed through the main circuit on-off valves 713a, 713b, 713c, 713d. It enters the exchangers 731, 732, 733, and 734, is heated by exchanging heat with the outdoor air, returns to the compressor 75 as a gas refrigerant. By repeating the heating operation in the heating cycle described above, the heating operation is continued.

  During such a heating operation, the outdoor heat exchanger 73 takes a heat from the outdoor air and becomes low in temperature, and may become 0 ° C. or less and frost on the heat transfer surface. This phenomenon becomes conspicuous when the temperature of the outside air is low and the humidity is high, and the flow of the outdoor air 631 is reduced by the frost adhering to the outdoor air flow surface, thereby reducing the air volume of the outdoor fan 631. When the air volume of the outdoor fan 631 decreases, the temperature of the outdoor heat exchanger 73 further decreases, and frost is more likely to be formed. Thus, the amount of frost formation in the outdoor heat exchanger 73 continues to increase, the amount of heat pumped from the outdoor air by the air conditioner 1 decreases, the heating capacity also decreases, the room cannot be heated sufficiently, and the heating function is lost. Therefore, defrosting operation is necessary.

  Next, the defrosting / heating operation in the heating cycle of the air conditioner according to the present embodiment will be described below with reference to FIGS. FIG. 5 shows the first heat exchanger of the air conditioner according to this embodiment, FIG. 6 shows the second heat exchanger of the air conditioner according to this embodiment, and FIG. 7 shows the air conditioner according to this embodiment. FIG. 8 is a refrigeration cycle diagram showing the flow of the refrigerant when the third heat exchanger and FIG. 8 each defrost the fourth heat exchanger of the air conditioner according to the present embodiment.

  As described above, when the heating operation is performed, on the day when the temperature is low and the humidity is high, the outdoor heat exchanger 73 is frosted and the heating capacity is reduced. When the refrigerant temperature detection sensor 812 is below the predetermined temperature and the heating operation in the heating cycle is performed for a predetermined time or more, it is considered that the amount of frost formation has reached the predetermined amount, and the heating cycle is removed. Perform frost operation.

  In this defrosting operation, the four-way valve 72 is made the same as in the heating operation as shown in FIG. 5, the first main circuit on-off valve 713a is closed, the second main circuit on-off valve 713b, the third main circuit on-off valve 713c, 4 The main circuit on-off valve 713d is opened, the first bypass on-off valve 715a is opened, the second bypass on-off valve 715b, the third bypass on-off valve 715c, and the fourth bypass on-off valve 715d are closed, and the inside of the outdoor heat exchanger 73 The first heat exchanger 731 functions as a condenser, and the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 function as an evaporator to perform defrosting and heating at the same time. Forms a defrosting / heating cycle. At this time, the outdoor air blowing motor 633 is operated or stopped at a low speed, and the indoor air blowing motor 313 controls the operation so that the blowing temperature can be maintained at a predetermined temperature or higher.

  Here, the gas refrigerant sucked into the compressor 75 is compressed by the compressor 75, becomes a high-temperature and high-pressure gas refrigerant, is discharged to the discharge pipe 711, branches in the middle, and one refrigerant is the four-way valve 72. And the other refrigerant enters the hot gas bypass pipe 715.

  One refrigerant that has entered the four-way valve 72 flows in the direction of the solid line arrow in FIG. 6, enters the indoor heat exchanger 33, exchanges heat with the indoor air, and is condensed to become a liquid or gas-liquid mixed refrigerant. At this time, the room is heated. The refrigerant that has become a liquid or gas-liquid mixed refrigerant exits the indoor unit 2 and enters the outdoor unit 6, flows through the hot pipe 713 e, melts the surrounding ice pieces that have fallen during defrosting, and then exits the outdoor unit 6. Discharge.

  The refrigerant passing through the hot pipe 713e enters the decompression device 74, expands due to decompression, and becomes a low-pressure gas-liquid mixed refrigerant. This gas-liquid mixed refrigerant flows in the direction of the broken arrow indicating the flow of the low-pressure refrigerant in FIG. 5, and passes through the second main circuit on-off valve 713b, the third main circuit on-off valve 713c, and the fourth main circuit on-off valve 713d. , Enters the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 of the outdoor heat exchanger 73 serving as an evaporator, is heated by exchanging heat with outdoor air, and compressed as a gas refrigerant Return to machine 75.

  On the other hand, the refrigerant that has entered the hot gas bypass pipe 715 flows in the direction of the solid line arrow in FIG. 5 and enters the first heat exchanger 731 of the outdoor heat exchanger 73 via the first bypass on-off valve 715a. Since the refrigerant that has entered the first heat exchanger 731 is high temperature and pressure, the frost adhering to the first heat exchanger 731 is melted and allowed to flow downward. The molten water that has flowed down flows into the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 that are located on the lower side acting as an evaporator, and initially the second heat exchanger 732 The third heat exchanger 733 and the fourth heat exchanger 734 flow down while melting the frost, and as it flows down, the temperature becomes lower, and when the outside air temperature is low, the ice is frozen again at the end.

  At this time, the molten water flows down while applying heat to the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734, and the heat flows to the second heat exchanger 732 and the third heat exchanger 733. And the vaporization of the refrigerant | coolant inside the 4th heat exchanger 734 is accelerated | stimulated. That is, a part of the heat used for melting frost in the first heat exchanger 731 on the upper side of the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 on the lower side. Part of the frost is melted and recovered, contributing to the vaporization of the internal refrigerant, and the amount of heat from defrosting is used effectively.

  The refrigerant defrosted from the first heat exchanger 731 merges with the refrigerant vaporized in the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 when leaving the first heat exchanger 731. Return to the compressor 75. When the defrosting operation of the first heat exchanger 731 is performed for a predetermined time or the refrigerant temperature detection sensor 811a at the outlet of the first heat exchanger 731 rises to a predetermined temperature, the second heat exchanger 732 is defrosted next.

  To switch to defrosting of the second heat exchanger 732, the first main circuit on / off valve 713a, the third main circuit on / off valve 713c and the fourth main circuit on / off valve 713d are opened, the second main circuit on / off valve 713b is closed, The first bypass on / off valve 715a, the third bypass on / off valve 715c and the fourth bypass on / off valve 715d are closed, the second bypass on / off valve 715b is opened, and the second heat exchanger 732 in the outdoor heat exchanger 73 is condensed. The first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 function as an evaporator to form a defrosting / heating operation cycle in which defrosting and heating are performed simultaneously. . At this time, the outdoor air blowing motor 633 is operated or stopped at a low speed, and the indoor air blowing motor 313 controls the operation so that the blowing temperature can be maintained at a predetermined temperature or higher.

  Here, the flow of the refrigerant from the four-way valve 72 to the indoor heat exchanger 33 and decompressed by the decompression device 74 is the same as when the first heat exchanger 731 is defrosted. The refrigerant decompressed by the decompression device 74 flows in the direction of the broken arrow in FIG. 6, and passes through the first main circuit on / off valve 713a, the third main circuit on / off valve 713c, and the fourth main circuit on / off valve 713d. The first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 of the outdoor heat exchanger 73, which enter the heat exchange with the outdoor air, are heated, become a gas refrigerant, and enter the compressor 75. The gas refrigerant returns to the compressor 75.

  The refrigerant that has entered the hot gas bypass pipe 715 flows in the direction of the solid line arrow in FIG. 6 and enters the second heat exchanger 732 of the outdoor heat exchanger 73 via the second bypass on-off valve 715b. Since the refrigerant that has entered the second heat exchanger 732 has a high temperature and a high pressure, the frost adhering to the second heat exchanger 732 is melted and allowed to flow downward. The molten water that has flowed down is discharged out of the outdoor unit 6 through the discharge port of the defrost water. The refrigerant that has defrosted the frost of the second heat exchanger 732 is a refrigerant that has vaporized in the first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 when leaving the second heat exchanger 732. The merger returns to the compressor 75. When the defrosting operation of the second heat exchanger 732 elapses for a predetermined time or when the refrigerant temperature detection sensor 811b at the outlet of the second heat exchanger 732 rises to a predetermined temperature, the defrosting of the third heat exchanger 733 is next performed. Do.

  To switch to defrosting of the third heat exchanger 733, the first main circuit on / off valve 713a, the second main circuit on / off valve 713b and the fourth main circuit on / off valve 713d are opened, the third main circuit on / off valve 713c is closed, The first bypass opening / closing valve 715a, the second bypass opening / closing valve 715b, and the fourth bypass opening / closing valve 715d are closed, the third bypass opening / closing valve 715c is opened, and the third heat exchanger 733 in the outdoor heat exchanger 73 is condensed. The first heat exchanger 731, the second heat exchanger 732, and the fourth heat exchanger 734 function as an evaporator to form a defrosting / heating operation cycle in which defrosting and heating are performed simultaneously. . At this time, the outdoor air blowing motor 633 is operated or stopped at a low speed, and the indoor air blowing motor 313 controls the operation so that the blowing temperature can be maintained at a predetermined temperature or higher.

  Here, the flow of the refrigerant from the four-way valve 72 to the indoor heat exchanger 33 and decompressed by the decompression device 74 is the same as when the first heat exchanger 731 is defrosted. The refrigerant decompressed by the decompression device 74 flows in the direction of the broken arrow in FIG. 7, and passes through the first main circuit on / off valve 713a, the second main circuit on / off valve 713b, and the fourth main circuit on / off valve 713d. It enters the first heat exchanger 731, the second heat exchanger 732, and the fourth heat exchanger 734 of the outdoor heat exchanger 73, and is heated by exchanging heat with the outdoor air and becomes a gas refrigerant to the compressor 75. The gas refrigerant returns to the compressor 75.

  The refrigerant that has entered the hot gas bypass pipe 715 flows in the direction of the solid line arrow in FIG. 7 and enters the third heat exchanger 733 of the outdoor heat exchanger 73 via the third bypass on-off valve 715c. Since the refrigerant that has entered the third heat exchanger 733 has high temperature and pressure, the frost adhering to the third heat exchanger 733 is melted and allowed to flow downward. The molten water that has flowed down is discharged out of the outdoor unit 6 through the discharge port of the defrost water. The refrigerant that has defrosted the frost of the third heat exchanger 733 is the refrigerant that has vaporized in the first heat exchanger 731, the second heat exchanger 732, and the fourth heat exchanger 734 when leaving the third heat exchanger 733. The merger returns to the compressor 75. When the defrosting operation of the third heat exchanger 733 elapses for a predetermined time or when the refrigerant temperature detection sensor 811c at the outlet of the third heat exchanger 733 rises to a predetermined temperature, the defrosting of the fourth heat exchanger 734 is next performed. Do.

  In order to switch to defrosting of the fourth heat exchanger 734, the first main circuit on / off valve 713a, the second main circuit on / off valve 713b and the third main circuit on / off valve 713c are opened, the fourth main circuit on / off valve 713d is closed, The first bypass opening / closing valve 715a, the second bypass opening / closing valve 715b, and the third bypass opening / closing valve 715c are closed, the fourth bypass opening / closing valve 715d is opened, and the fourth heat exchanger 734 in the outdoor heat exchanger 73 is condensed. The first heat exchanger 731, the second heat exchanger 732, and the third heat exchanger 733 function as an evaporator to form a defrosting / heating operation cycle in which defrosting and heating are performed simultaneously. . At this time, the outdoor air blowing motor 633 is operated or stopped at a low speed, and the indoor air blowing motor 313 controls the operation so that the blowing temperature can be maintained at a predetermined temperature or higher.

  Here, the flow of the refrigerant from the four-way valve 72 to the indoor heat exchanger 33 and decompressed by the decompression device 74 is the same as when the first heat exchanger 731 is defrosted. The refrigerant depressurized by the decompression device 74 flows in the direction of the broken arrow in FIG. 8, and passes through the first main circuit on / off valve 713a, the second main circuit on / off valve 713b, and the third main circuit on / off valve 713c. The first heat exchanger 731, the second heat exchanger 732, and the third heat exchanger 733 of the outdoor heat exchanger 73, which enter the heat exchange with the outdoor air, are heated and become a gas refrigerant to the compressor 75. The gas refrigerant returns to the compressor 75.

  The refrigerant that has entered the hot gas bypass pipe 715 flows in the direction of the solid line arrow in FIG. 8 and enters the fourth heat exchanger 734 of the outdoor heat exchanger 73 via the fourth bypass on-off valve 715d. Since the refrigerant that has entered the fourth heat exchanger 734 has a high temperature and a high pressure, the frost adhering to the fourth heat exchanger 734 is melted and allowed to flow downward. The molten water that has flowed down is discharged out of the outdoor unit 6 through the discharge port of the defrost water. The refrigerant that has defrosted the frost of the fourth heat exchanger 734 is the refrigerant that has vaporized in the first heat exchanger 731, the second heat exchanger 732, and the third heat exchanger 733 after leaving the fourth heat exchanger 734. The merger returns to the compressor 75. When the defrosting operation of the fourth heat exchanger 734 elapses for a predetermined time or when the refrigerant temperature detection sensor 811d at the outlet of the fourth heat exchanger 734 rises to a predetermined temperature, the first main circuit on-off valve 713a and the second main circuit The on-off valve 713b, the third main circuit on-off valve 713c, and the fourth main circuit on-off valve 713d are opened, and the first bypass on-off valve 715a, the second bypass on-off valve 715b, the third bypass on-off valve 715c, and the fourth bypass on-off valve 715d are opened. It is closed, the defrosting / heating operation is finished, and it immediately returns to the heating operation of FIG.

  Here, since the lower part of the outdoor heat exchanger 73 passes through the defrosted water flowing from the upper part, water droplets are likely to remain from the upper part. When the partial defrosting / heating operation is completed with the water droplets remaining and the heating operation is started, the remaining water droplets freeze and block the outdoor air flow. If the ventilation of the outdoor air is obstructed, as described above, it becomes easier for frost to grow.

  Therefore, when defrosting the outdoor heat exchanger 73, the first heat exchanger 731, the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 are defrosted in this order from the upper side. The lower defrosting time is longer than the defrosting time of the upper heat exchanger 731 previously performed. Thus, when the outdoor heat exchanger 73 is frosted and the frost amount reaches a predetermined amount that requires defrosting, the partial defrosting / heating operation is performed in order from the heat exchanger on the upper side. Since hot gas (hot gas from the hot gas bypass pipe) flows through the refrigerant circuit on the upper side, frost attached to the air side heat transfer surface of the refrigerant circuit on the upper side of the outdoor heat exchanger 73 is melted and flows downward. .

  When the temperature of the molten water is high, the molten water touches the frost on the air side heat transfer surface of the heat exchanger on the lower side and further flows down while melting it with the sensible heat of the molten water itself. At this time, the portion where the frost has melted in the heat exchanger on the lower side is removed from the frost that was hindering heat transfer, so the heat transfer from the outside air to the refrigerant is performed smoothly, and the heat exchange capability is improved. It recovers and suppresses the decline in indoor heating capacity. When the temperature of the flowing molten water falls to the melting point, the molten water flows down without further melting of the frost, and is cooled by the refrigerant in the lower refrigerant circuit flowing in the lower heat exchanger while flowing down. Solidify.

  At this time, since the heat of solidification of the molten water warms the refrigerant in the lower refrigerant circuit, the amount of heat used to melt the frost is recovered by the heat exchanger on the upper side. When the defrosting / heating operation for defrosting the upper heat exchanger is completed, the defrosting / heating operation for defrosting the lower heat exchanger in order is started. Since hot gas from the compressor 75 is caused to flow through the refrigerant circuit that performs defrosting, the frost attached to the air-side heat transfer surface of the corresponding refrigerant circuit melts and flows downward.

  At this time, the heat exchanger immediately after the completion of the defrosting removes the frost that has hindered the heat transfer, so the heat transfer from the outside air to the refrigerant is performed smoothly, and the heat exchange capacity is restored. , Suppresses the decrease in indoor heating capacity. Thus, heating can be continued while suppressing a significant decrease in heating capacity even during defrosting / heating operation.

  Further, during the defrosting / heating operation, the frosting amount of the heat exchanger below the defrosted heat exchanger may temporarily increase. However, since the defrosting / heating operation for defrosting the heat exchanger on the lower side is subsequently performed, the heat exchanger on the lower side is also defrosted. Therefore, the frost of the lower heat exchanger does not continue to increase due to the defrosting of the upper heat exchanger.

  In this way, the total time required for the defrosting / heating operation can be shortened compared to the case where the reverse cycle defrosting operation is performed. Moreover, since the fall of the discharge temperature of the compressor 75 is suppressed at this time, the fall of heating capability can also be suppressed. For this reason, defrosting can be performed while heating the room, and the time required for the defrosting / heating operation can be shortened.

  Next, the limited defrosting / heating operation in the heating cycle of the air conditioner according to the present embodiment will be described below. Under actual usage conditions, the overall amount of frost on the outdoor heat exchanger may not be constant depending on the weather conditions surrounding the outdoor heat exchanger (changes in temperature, whether there is rainfall or snowfall, changes in wind direction and wind speed, etc.) . For example, during bad weather such as stormy snow, the frosting on the heat exchanger of the outdoor unit is not always constant depending on the installation status of the outdoor unit (the presence or absence of a wind and snow protection structure of the outdoor unit and the influence of surrounding buildings). May concentrate on the department. Since the defrosting / heating operation is controlled when the refrigerant temperature falls below a certain value by the refrigerant temperature detection sensor 812, the defrosting / heating operation is performed even if a part of the heat exchanger with a large amount of frost formation is included. Perform heating operation. Therefore, it can be said that the defrosting efficiency is good because the defrosting / heating operation is performed while sequentially switching the heat exchangers of the refrigerant circuits divided into a plurality according to the above control even for heat exchangers that do not need to be defrosted originally. Absent.

  Therefore, only in the case where the amount of frost formation on the outdoor heat exchanger is extremely large, instead of defrosting the heat exchanger in order by defrosting / heating operation, only the necessary parts are limited. Perform limited defrosting and heating operation to defrost. Here, assuming that the outdoor heat exchanger with a large amount of frost formation is the outdoor second heat exchanger 732, the limited defrosting / heating operation of the second heat exchanger 732 will be described with reference to FIG.

  In order to switch from the heating operation state to the limited defrosting / heating operation of the second heat exchanger 732, the first main circuit on / off valve 713a, the third main circuit on / off valve 713c, and the fourth main circuit on / off valve 713d are opened, 2 The main circuit on-off valve 713b is closed, the first bypass on-off valve 715a, the third bypass on-off valve 715c and the fourth bypass on-off valve 715d are closed, the second bypass on-off valve 715b is opened, and the inside of the outdoor heat exchanger 73 The second heat exchanger 732 functions as a condenser, and the first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 function as an evaporator to perform defrosting and heating at the same time. Forms a defrosting / heating cycle. At this time, the outdoor air blowing motor 633 is operated at a low speed, and the indoor air blowing motor 313 controls the operation so that the blowing temperature can be maintained at a predetermined temperature or higher.

  Here, the flow of the refrigerant from the four-way valve 72 to the indoor heat exchanger 33 and decompressed by the decompression device 74 is the same as when the first heat exchanger 731 is defrosted. The refrigerant decompressed by the decompression device 74 flows in the direction of the broken arrow in FIG. 6, and passes through the first main circuit on / off valve 713a, the third main circuit on / off valve 713c, and the fourth main circuit on / off valve 713d. The first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 of the outdoor heat exchanger 73, which enter the heat exchange with the outdoor air, are heated, become a gas refrigerant, and enter the compressor 75. The gas refrigerant returns to the compressor 75.

  The refrigerant that has entered the hot gas bypass pipe 715 flows in the direction of the solid line arrow in FIG. 6 and enters the second heat exchanger 732 of the outdoor heat exchanger 73 via the second bypass on-off valve 715b. Since the refrigerant that has entered the second heat exchanger 732 has a high temperature and a high pressure, the frost adhering to the second heat exchanger 732 is melted and allowed to flow downward. The molten water that has flowed down is discharged out of the outdoor unit 6 through the discharge port of the defrost water. The refrigerant that has defrosted the frost of the second heat exchanger 732 is a refrigerant that has vaporized in the first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 when leaving the second heat exchanger 732. The merger returns to the compressor 75. When the defrosting operation of the second heat exchanger 732 elapses for a predetermined time or when the refrigerant temperature detection sensor 811b at the outlet of the second heat exchanger 732 rises to a predetermined temperature, the first main circuit on-off valve 713a and the second main circuit The on-off valve 713b, the third main circuit on-off valve 713c, and the fourth main circuit on-off valve 713d are opened, and the first bypass on-off valve 715a, the second bypass on-off valve 715b, the third bypass on-off valve 715c, and the fourth bypass on-off valve 715d are opened. It is closed, the partial defrosting / heating operation is terminated, and the operation immediately returns to the heating operation of FIG.

  Here, the transition determination to the limited defrosting / heating operation will be described. The control device 10 determines whether to shift to the limited defrosting / heating operation at the end of the defrosting / heating operation. In order to defrost the heat exchangers of a plurality of divided refrigerant circuits in order in the defrosting / heating operation (to defrost the next heat exchanger after a predetermined time of the defrosting operation of one heat exchanger) The temperature at the end of the defrosting / heating operation of each heat exchanger can be monitored by the refrigerant temperature detection sensor 811 attached to each heat exchanger. When there is no extreme difference in the amount of frost formation on each heat exchanger, the temperature difference of the refrigerant temperature detection sensor at the end of defrosting of each heat exchanger is small.

However, when the difference in the frost amount of the heat exchanger becomes large, the detection temperature T _MIN of the refrigerant temperature detection sensor at the time when the defrosting of the heat exchanger with the large frost amount ends is the other heat exchanger with the small frost amount. This is about 5 to 15 ° C. lower than the average T _AVE of the detection temperature of the refrigerant temperature detection sensor at the end of defrosting.

Therefore, only the defrosting-shift determination condition to the heating operation, less heat of the detected temperature T _MIN and other frost amount of refrigerant temperature sensor of frost formation amount of large heat exchanger defrosting and heating operation at the end Refrigerant temperature detection at the end of defrosting of a heat exchanger when the temperature difference ΔT with respect to the average T _AVE of the detection temperature of the refrigerant temperature detection sensor at the end of defrosting of the exchanger exceeds 5 ° C. It is assumed that the detection temperature T _{MIN of the} sensor is less than 0 ° C. (T _MIN <0) (if the refrigerant temperature detected by the refrigerant temperature detection sensor 811 is less than 0 °, frost may remain unmelted) . In this way, after satisfying the condition for determining the transition to the limited defrosting / heating operation at the end of the defrosting / heating operation, after performing the heating operation for the defrosting prohibition time (defrosting many times after the defrosting / heating operation is completed). Since the heating efficiency decreases when the operation is performed, a defrosting operation prohibition time is provided immediately after the completion of the defrosting / heating operation, and the defrosting operation is not performed during this prohibition time), and the limited defrosting / heating operation is performed. .

Here, it is assumed that the heat exchanger with a large amount of frost formation is the second heat exchanger 732, and a determination example of the limited defrosting / heating operation will be described with reference to FIG. At the end of the defrosting / heating operation, the detection temperature T _a of the refrigerant temperature detection sensor 811a of the first heat exchanger 731 is 3 ° C., and the detection temperature T _b of the refrigerant temperature detection sensor 811b of the second heat exchanger 732 is −3. Assuming that the detection temperature T _c of the refrigerant temperature detection sensor 811c of the third heat exchanger 733 is 5 ° C., the detection temperature T _d of the refrigerant temperature detection sensor 811d of the fourth heat exchanger 734 is 4 ° C. When ΔT is calculated, the following equation is obtained.

ΔT = T _AVE −T _MIN = (T _a + T _c + T _d ) / 3−T _b = 7 [° C.]
Therefore, since ΔT> 5 and T _MIN = T _b <0, the limited defrosting / heating operation transition condition of the second heat exchanger 732 is determined in order to satisfy the limited defrosting / heating operation transition condition.

  In this way, by performing limited defrosting / heating operation that defrosts only limited places as necessary, defrosting is further performed than defrosting / heating operation that sequentially defrosts a plurality of divided outdoor heat exchangers. Can be shortened and the defrosting efficiency is improved. For example, when an outdoor heat exchanger divided into four parts is considered, assuming that the time of defrosting / heating operation per refrigerant circuit including the heat exchanger to be defrosted is almost the same, limited defrosting / heating The time required for operation is about a quarter of the time required for defrosting / heating operation.

  Next, generally, when heating under a temperature condition where frost formation occurs, the outside air temperature is often low, and a high condensing temperature is required to raise the temperature of the hot air, and the suction pressure of the compressor 75 is Since the outside air temperature is low, the temperature is lowered, so that the compression ratio is increased and the efficiency of the compressor 75 is decreased. In order to compensate for this, it is necessary to increase the number of rotations to ensure the circulation amount of the refrigerant when using a rotation number control compressor. Moreover, since the work amount of the compressor 75 is also added to the heating capacity, the compressor 75 is fully operated to ensure the heating capacity. For this reason, the compressor 75 is driven with a high load, and the compressor 75 is kept at a high temperature. When the defrosting / heating operation is started from this state, since the compressor 75 is kept at a high temperature, the refrigerant discharged from the compressor 75 flows through the hot gas bypass circuit at a high temperature and flows into the outdoor heat exchanger 73. Then defrost.

  In general, the outdoor fan 631 that blows air to the outdoor heat exchanger 73 circulates a large amount of outside air so that heat exchange can be performed efficiently, and thus an axial fan 631 is used. Since the wind pressure that can be generated by the axial fan is not so great, the structure of the outdoor unit 6 is that the outside air inlet, the outdoor heat exchanger 73, the axial fan 631, and the outside air outlet are arranged in a straight line, and the ventilation path is simplified. Thus, the pressure loss of ventilation is suppressed.

  Further, as the outside air temperature decreases, the discharge temperature of the compressor 75 is shifted to the high temperature side and controlled, and the defrosting prohibition period is shortened. In other words, a temperature detection sensor that detects the ambient temperature of the air conditioner, that is, the outside air temperature, is separately provided, and based on the temperature decrease by this sensor, the rotation speed of the compressor is increased or the throttle of the decompression device is throttled. Thus, the compressor discharge temperature is shifted to the high temperature side to increase the heating capacity, and the decrease in the outside air temperature accelerates the growth of frost, so that the defrosting period can be shortened so that the defrosting operation can be performed. Take control. As a result, the heat storage amount of the compressor 75 is increased, the defrosting / heating operation or the limited defrosting / heating operation time is shortened, and the recovery of the discharge temperature of the compressor 75 when returning to the heating operation is accelerated. , Heating capacity decline time is shortened. For this reason, the room temperature change at the time of defrosting / heating operation or limited defrosting / heating operation is suppressed even at a low outside temperature.

  Further, during the defrosting / heating operation or the limited defrosting / heating operation, the rotational speed of the outdoor fan 631 is decreased as compared with the heating operation, and when the outdoor air temperature is lower than a predetermined value, the outdoor fan is operated during the defrosting operation. To stop. Thus, by reducing the rotational speed of the outdoor fan 631 during defrosting / heating operation or limited defrosting / heating operation, from the melted water, fins, and pipes during defrosting / heating operation or limited defrosting / heating operation, The amount of heat taken away by the outdoor air by forced convection by the outdoor fan 631 is reduced, and frost melting proceeds efficiently.

  Further, when the temperature of the outside air is further lowered and the amount of heat released to the outside air is increased, the operation of the outdoor fan 631 is stopped. As a result, most of the amount of heat removed to the outside air by forced convection by the outdoor fan 631 is effectively used for melting frost, and the defrosting of the outdoor heat exchanger 73 proceeds efficiently. Therefore, the defrosting / heating operation or the limited defrosting / heating operation time can be shortened, and the defrosting / heating operation or the limited defrosting / heating operation is possible even at a low outside temperature.

  Further, the reverse cycle defrosting operation is performed by switching the four-way valve 72 only when the temperature of the outdoor heat exchanger 73 does not reach a predetermined value even if the defrosting / heating operation is performed until the longest defrosting operation time is reached. That is, if the heat exchanger refrigerant temperature detection sensors 811a to 811d do not reach 0 ° C. or higher, there is a possibility of residual frost, and therefore the reverse cycle defrost operation is performed. As a result, the reverse cycle defrosting operation is also performed for the frost near the refrigerant circuit outlet (outdoor heat exchanger inlet) of the outdoor heat exchanger 73 that has not been completely melted by the hot gas bypass defrosting in the heating cycle. Thus, the high-temperature refrigerant from the compressor 75 can be melted.

  In this way, complete defrosting operation without residual frost is performed even if residual frost is generated in normal defrosting / heating operation or limited defrosting / heating operation due to deterioration of air conditioner installation conditions and weather conditions. It can be carried out. For this reason, the range of the installation conditions and weather conditions which can be heated indoors can be widened.

  Next, the rising characteristics of heating according to another configuration example (actual measurement result when the heat exchanger is divided into two) according to the embodiment of the present invention will be described with reference to FIG. FIG. 9 is a characteristic diagram showing a change in room temperature during the start-up operation of the air conditioner shown in FIG. In this example, assuming a cold morning, both the room temperature and the outside air temperature are started at −5 ° C.

  As shown in the characteristics of FIG. 9, in the heating operation and the defrosting / heating operation method according to this embodiment, the defrosting operation time is as short as about 2 minutes (total defrosting in the first to fourth heat exchangers). Time, the time during which the room temperature is lowered in FIG. 9), and also during the defrosting / heating operation, a part of the outdoor heat exchanger acts as an evaporator to heat the room. The decrease is suppressed to about 3 ° C. when the room temperature is raised and to the same level when the room temperature is stable, and heating is continued while ensuring comfort. Furthermore, in the heating operation and the limited defrosting / heating operation method performed as necessary according to the present embodiment, the defrosting operation time is shorter than that during the defrosting / heating operation, and the limited defrosting / heating operation is performed. Since some of the outdoor heat exchangers also act as evaporators to heat the room, the decrease in room temperature is further suppressed than during the defrosting / heating operation, ensuring comfort and heating. Is continued. From FIG. 10, the time for the room temperature to reach from -5 ° C to 20 ° C is as short as 80 minutes.

  As described above, the air conditioner according to the embodiment of the present invention includes the following control device. That is, the control device performs the defrosting / heating operation in which heating is performed by the other heat exchanger while defrosting the partial heat exchanger of the refrigerant circuit divided into a plurality during the heating operation, and the defrosting of all the refrigerant circuits is completed. Thereafter, control is performed so as to return to the heating operation, and among the heat exchangers of the refrigerant circuit divided into a plurality during the heating operation, only the heat exchanger of the refrigerant circuit having a large amount of frost formation is limited and defrosted. When it is necessary, only the heat exchanger with a large amount of frost formation is limited and defrosting and heating with other heat exchangers is performed, and control is performed to return to the heating operation. It is.

  Further, the control device controls the discharge temperature of the compressor to be shifted to the high temperature side based on the decrease in the outside air temperature, and controls so as to shorten the defrosting prohibition period. , During the defrosting / heating operation and during the limited defrosting / heating operation, the rotational speed of the outdoor air blower is reduced more than during the heating operation, and the outdoor air blower operation is stopped during the defrosting when the outside air temperature is lower than the predetermined value. Furthermore, even if the control device performs defrosting / heating operation and limited defrosting / heating operation until the defrosting operation time is reached, the temperature of the outdoor heat exchanger does not reach a predetermined value. In this case, the control is performed so as to perform the reverse cycle defrosting operation by switching the four-way valve.

  As described above, the air conditioner according to the embodiment of the present invention is supported by the following specific configuration example. That is, the air conditioner performs the defrosting simultaneously with the heating to shorten the defrosting time while ensuring the indoor comfort, and the compressor 75, the four-way valve 72, the indoor heat exchanger 33, the pressure reducing device. 74 and an outdoor heat exchanger 73 are connected by a refrigerant pipe to form a refrigeration cycle, and a bypass circuit 715 is provided to flow hot gas from the discharge side of the compressor 75 to the outdoor heat exchanger 73. The outdoor heat exchanger 73 divides the refrigerant circuit vertically into two to four, for example, a first heat exchanger 731, a second heat exchanger 732, a third heat exchanger 733, and a fourth heat exchanger. 734 is configured.

  During the heating operation, the control device 10 includes the first main circuit on-off valve 713a, the second main circuit on-off valve 713b, the third main circuit on-off valve 713c, the fourth main circuit on-off valve 713d, and the first bypass on-off valve 715a, The second bypass opening / closing valve 715b, the third bypass opening / closing valve 715c, and the fourth bypass 715d are each appropriately opened and closed (as described above) to defrost the first heat exchanger 731 and another heat exchanger 732. After performing the defrosting / heating operation for heating at ˜734, the defrosting / heating operation for heating with other heat exchangers while defrosting the second to fourth heat exchangers 732 to 734 in the same manner is performed in order. Immediately after defrosting is completed for all heat exchangers, the heating operation is resumed. Further, during the heating operation, the control device 10 includes the first main circuit on-off valve 713a, the second main circuit on-off valve 713b, the third main circuit on-off valve 713c, the fourth main circuit on-off valve 713d, and the first bypass on-off valve 715a. The second bypass on / off valve 715b, the third bypass on / off valve 715c, and the fourth bypass 715d are appropriately opened and closed (as described above), and only the heat exchanger of the refrigerant circuit with a large amount of frost formation is limited and removed. Control is performed so as to immediately return to the heating operation after the limited defrosting / heating operation for heating with another heat exchanger while frosting.

1 is a schematic configuration diagram of an air conditioner according to an embodiment of the present invention. It is a figure which shows the structure of the refrigerating cycle in the air conditioner which concerns on this embodiment. It is a refrigeration cycle figure which shows the flow of the refrigerant | coolant at the time of air_conditionaing | cooling operation of the air conditioner which concerns on this embodiment. It is a refrigerating cycle figure which shows the flow of the refrigerant | coolant at the time of the heating operation of the air conditioner which concerns on this embodiment. It is a refrigeration cycle figure which shows the flow of the refrigerant | coolant at the time of defrosting the 1st heat exchanger of the air conditioner which concerns on this embodiment. It is a refrigerating cycle figure which shows the flow of the refrigerant | coolant when defrosting the 2nd heat exchanger of the air conditioner which concerns on this embodiment. It is a refrigerating cycle figure which shows the flow of the refrigerant | coolant when defrosting the 3rd heat exchanger of the air conditioner which concerns on this embodiment. It is a refrigeration cycle figure which shows the flow of the refrigerant | coolant when defrosting the 4th heat exchanger of the air conditioner which concerns on this embodiment. It is a characteristic view which shows the room temperature change at the time of the start-up operation of the air conditioner according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air conditioner 2 ... Indoor unit 5 ... Remote control 6 ... Outdoor unit 8 ... Connection piping 10 ... Control apparatus 33 ... Indoor heat exchanger 72 ... Four-way valve 73 ... Outdoor heat exchanger 74 ... Decompression unit 75 ... Compressor 76 ... Accumulator 311 ... Indoor fan 313 ... Indoor fan motor 631 ... Outdoor fan 633 ... Outdoor fan motor 710 ... Suction pipe 711 ... Discharge pipe 712 ... Usage side gas pipe 713 ... Liquid pipe 713a ... First main circuit on-off valve 713b ... Second main Circuit open / close valve 713a ... Third main circuit open / close valve 713d ... Fourth main circuit open / close valve 713e ... Hot pipe 714 ... Heat source side gas pipe 715 ... Hot gas bypass pipe 715a ... First bypass open / close valve 715b ... Second bypass open / close valve 715c ... third bypass on-off valve 715d ... fourth bypass on-off valve 716a ... first main circuit / bypass common pipe 716b ... first Main circuit / bypass common pipe 716c ... Third main circuit / bypass common pipe 716d ... Fourth main circuit / bypass common pipe 731 ... First heat exchanger 731a ... First heat exchanger upper refrigerant circuit 731b ... First heat exchanger Lower refrigerant circuit 732 ... second heat exchanger 732a ... second heat exchanger upper refrigerant circuit 732b ... second heat exchanger lower refrigerant circuit 733 ... third heat exchanger 733a ... third heat exchanger upper refrigerant circuit 733b 3rd heat exchanger lower refrigerant circuit 734 4th heat exchanger 734a 4th heat exchanger upper refrigerant circuit 734b 4th heat exchanger lower refrigerant circuit 811a 1st heat exchanger refrigerant temperature detection sensor 811b ... 2nd heat exchanger refrigerant temperature detection sensor 811c ... 3rd heat exchanger refrigerant temperature detection sensor 811d ... 4th heat exchanger refrigerant temperature detection sensor 812 ... Refrigerant temperature detection sensor

Claims (6)

A compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, and an outdoor heat exchanger are connected by a refrigerant pipe to form a refrigeration cycle, and the outdoor heat exchanger is divided into a plurality of units and connected in parallel. Corresponding to the refrigerant circuit of each outdoor heat exchanger, a main circuit on-off valve is provided on the inlet side during heating operation, and the discharge side of the compressor and the inlet side during heating operation of the refrigerant circuit of each outdoor heat exchanger are provided. A control device for providing a hot gas bypass circuit to be connected, providing a bypass on-off valve corresponding to the refrigerant circuit of each outdoor heat exchanger in the hot gas bypass circuit, and controlling each component of the on-off valve and the refrigeration cycle An air conditioner provided with
When starting defrosting of the outdoor heat exchanger during heating operation, the control device controls opening and closing of the main circuit on-off valve and a part of the bypass on-off valve, and among the plurality of outdoor heat exchangers A defrosting / heating operation is performed in which a part is defrosted and heated by another outdoor heat exchanger, and the defrosting / heating operation is sequentially repeated for all of the plurality of outdoor heat exchangers, and then the heating operation is resumed. To control and
Further, the control device detects and determines an outdoor heat exchanger with a large amount of frost formation in the plurality of outdoor heat exchangers after the defrosting / heating operation is finished, and the corresponding outdoor heat exchanger The open / close control of the main circuit on / off valve and the bypass on / off valve corresponding to the above is performed, and limited defrosting / heating operation is performed in which only the plurality of the corresponding outdoor heat exchangers are defrosted and heated by other outdoor heat exchangers. After that, the air conditioner is controlled to return to the heating operation. In claim 1,
The control device monitors the refrigerant temperature of each of the outdoor heat exchangers when making a transition to the limited defrosting / heating operation, and performs a transition control by determining based on these refrigerant temperatures. Air conditioner. In claim 2,
The control device is configured to determine whether to move to the limited defrosting / heating operation, wherein the outdoor heat in which the minimum value is less than 0 ° C. and the refrigerant temperature is the minimum value among the refrigerant temperatures of the outdoor heat exchangers. When the difference between the average value of the refrigerant temperature of the outdoor heat exchanger other than the exchanger and the minimum value of the refrigerant temperature exceeds 5 ° C., control is performed so as to shift to the limited defrosting / heating operation. A featured air conditioner. In claim 1, 2 or 3,
The control device controls the compressor or the pressure reducing device so that the discharge temperature of the compressor becomes higher based on the detected decrease in the outside air temperature, and removes after the defrosting / heating operation is finished. An air conditioner that is controlled to shorten the frost operation prohibition period. In claim 1, 2 or 3,
The control device lowers the rotation speed of the blower for the outdoor heat exchanger or stops the blower during the defrosting / heating operation or during the limited defrosting / heating operation than in the heating operation. An air conditioner characterized by being controlled as follows. In claim 1,
When the refrigerant temperature of the outdoor heat exchanger does not reach a predetermined value even after performing the defrosting / heating operation or the limited defrosting / heating operation, the control device switches the four-way valve to remove the reverse cycle. An air conditioner controlled to perform frost operation.

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