JP5882152B2 - Air conditioner - Google Patents

Description

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

  As background art of this technical field, Patent Document 1 states that “the outdoor heat exchangers are divided into a plurality of units and connected in parallel, and the heating operation inlet side is mainly connected to the refrigerant circuit of each of the outdoor heat exchangers connected in parallel. A circuit open / close valve is provided, a hot gas bypass circuit connected to the discharge side of the compressor and the heating operation inlet side of the refrigerant circuit of each outdoor heat exchanger is provided, and the hot gas bypass circuit corresponds to the refrigerant circuit of each outdoor heat exchanger The air conditioner is provided with a bypass on-off valve and a control device that controls each component of the on-off valve and the refrigeration cycle, and the control device starts defrosting of the outdoor heat exchanger during heating operation In this case, a part of the main circuit on / off valve and the bypass on / off valve are controlled to be opened / closed, and a part of the plurality of outdoor heat exchangers is defrosted and heated by other outdoor heat exchangers. , Defrosting / heating operation for all outdoor heat exchangers After repeating controls to return to the heating operation "that discloses (see claim 1).

JP 2009-281698 A

  Here, among heat exchangers that are not defrosted among the plurality of heat exchangers, the heat exchange capability is reduced due to the formation of frost, and thus the heating capability is also reduced. On the other hand, the defrosted heat exchanger among the plurality of heat exchangers is improved in heating capacity because frost formed is removed and heat exchange capacity is improved.

  In the air conditioner of Patent Document 1, a plurality of outdoor heat exchangers connected in parallel for defrosting / heating operation are configured to have the same size. When performing the defrosting / heating operation with such an air conditioner of Patent Document 1, while performing the defrosting operation on the first heat exchanger, heating is performed with the other frosting heat exchanger. Ability is reduced. On the other hand, while the next heat exchanger is defrosting, it is heated by another heat exchanger, but since the first heat exchanger is defrosted, the first heat exchanger is defrosted. The heat exchange capacity is improved and the heating capacity is improved as compared to when operating. Furthermore, while the last heat exchanger is being defrosted, it is heated by another heat exchanger. However, since all other heat exchangers are defrosted, the heat exchange capacity is further improved. The heating capacity is greatly improved compared to when the first heat exchanger is defrosting.

  That is, when performing the defrosting / heating operation with the air conditioner of Patent Document 1, the heating capacity during the defrosting / heating operation greatly fluctuates, and in particular, the heating capacity is reduced while the first heat exchanger is defrosted. It becomes low and the discomfort of the air conditioner user increases.

  An object of the present invention is to suppress the fluctuation of the heating capacity even during the defrosting / heating operation and to reduce the discomfort of the air conditioner user.

An air conditioner according to the present invention includes a compressor, a four-way valve, an indoor heat exchanger, a decompression device, a refrigeration cycle in which a plurality of outdoor heat exchangers connected in parallel and different sizes are sequentially connected by a refrigerant pipe, and a refrigeration cycle An air conditioner comprising: a hot gas bypass circuit that branches between the discharge side of the compressor and the four-way valve and is connected between the decompression device and the inlet side of each of the plurality of outdoor heat exchangers during heating operation In the refrigeration cycle, in the heating operation mode in which the refrigerant is circulated in the order of the compressor, the four-way valve, the indoor heat exchanger, the pressure reducing device, the outdoor heat exchanger, and the compressor, and in the bypass circuit, the refrigerant is supplied to the compressor. In the defrosting operation in which the predetermined outdoor heat exchanger and the compressor are circulated in the order, and the refrigeration cycle, the refrigerant is used as the outdoor heat other than the compressor, the four-way valve, the indoor heat exchanger, the decompression device, and the predetermined outdoor unit. Exchanger, compressor A heating operation of circulating the order, and the defrosting and heating mode for performing the in defrosting, the heating operation mode, performing the defrosting operation from the always smaller outdoor heat exchanger in this order.

  According to the present invention, the outdoor heat exchanger includes a plurality of outdoor heat exchangers connected in parallel and having different sizes, and the defrosting operation is sequentially performed from the small outdoor heat exchanger in the defrosting / heating operation mode. While the defrosting operation is sequentially performed, the size of the outdoor heat exchanger that performs the heating operation (the outdoor heat exchanger other than the outdoor heat exchanger that performs the defrosting operation) is gradually reduced, but the heat exchange capacity is gradually increased. Therefore, even during the defrosting / heating operation, fluctuations in the heating capacity can be suppressed, and in particular, the heating capacity can be maintained even while the first heat exchanger in which the heating capacity is greatly reduced is defrosted. As a result, the discomfort of the air conditioner user can be reduced.

Air conditioner configuration diagram Configuration diagram of refrigeration cycle Refrigeration cycle diagram showing refrigerant flow during cooling operation Refrigeration cycle diagram showing refrigerant flow during heating operation Refrigeration cycle diagram showing the flow of refrigerant that defrosts the first heat exchanger Refrigeration cycle diagram showing the flow of refrigerant for defrosting the second heat exchanger Refrigeration cycle diagram showing the flow of refrigerant for defrosting the third heat exchanger Refrigeration cycle diagram showing the flow of refrigerant for defrosting the fourth heat exchanger The figure which shows the composition of the refrigerating cycle which changed the division ratio of the outdoor heat exchanger

  Hereinafter, examples will be described with reference to the drawings.

  (Embodiment 1) First, the overall structure of an air conditioner will be described with reference to FIG. FIG. 1 is a configuration diagram of an air conditioner.

  The air conditioner 1 includes a refrigeration cycle, a blower, and a control system that controls them. The air conditioner 1 is a separate type air conditioner in which the indoor unit 2 and the outdoor unit 6 are connected via a refrigerant pipe 8, electric 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 decompression device 74, an indoor heat exchanger 33, and bypass on / off valves 715a, 715b, 715c, 715d. And connecting them through refrigerant piping. The refrigerant pipe is composed of 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 main circuit / bypass common pipe 716a, 716b, 716c and 716d, and the like. Is done.

  The indoor heat exchanger 33 is housed in the indoor unit 2, and 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, bypass on / off 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 a heat exchange fin, 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 the 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, 734 is connected to the decompression device 74 via main circuit on-off valves 713a, 713b, 713c, 713d. Further, the discharge pipe of the compressor 75 branches from between the heat exchangers 731, 732, 733, 734 and the main circuit on-off valves 713a, 713b, 713c, 713d, and passes through 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. In the present embodiment, the pressure reducing device 74 is constituted by an expansion valve whose throttle opening can be controlled, for example, an electric type.

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

  The blower in the air conditioner 1 includes an outdoor blower 63 accommodated in the outdoor unit 6 and an indoor blower 31 accommodated in the indoor unit 2. The outdoor air blower includes an outdoor fan 631 that distributes outdoor air to the outdoor heat exchanger 73 and an outdoor air 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 this embodiment, an axial fan is used as the outdoor fan 631 and a cross-flow fan is used as the indoor fan 311.

  The control system in the air conditioner 1 includes the refrigerant temperature detection sensors 811a, 811b, 811c, 811d, and 812 and the 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 a refrigerant temperature detection sensor 812 that detects the outlet temperature of the outdoor heat exchanger 73 during 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, the main circuit on-off valves 713a, 713b, 713c, 713d and the bypass on-off valves 715a, 715b, 715c, 715d are controlled. In the present embodiment, the control device 10 shows a control device having a function to calculate and a control device having a function to control each device, but these may be configured separately, or A control device having a function of controlling each device may be further divided.

  Next, the operation of the air conditioner 1 will be described with reference to FIGS.

  First, the cooling operation in the cooling cycle will be described with reference to FIG. 3, 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, the bypass on / off valves 715a, 715b, 715c, 715d is closed to form a cooling operation cycle, and the compressor 75, the outdoor fan motor 633, and the indoor fan 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, and 734 of the condenser 73, and is cooled and condensed by heat exchange with the outdoor air to become 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 arrow indicating the flow of the low-pressure refrigerant in FIG. 3, exits the outdoor unit 6, enters the indoor unit 2, enters the indoor heat exchanger 33 serving as an evaporator, and The inside of the room is cooled by heat exchange with itself, and is heated to return to the compressor 75 as a gas refrigerant.

  Next, the heating operation in the heating cycle will be described with reference to FIG. In the heating operation in FIG. 4, 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 an 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 condensed into the liquid or gas-liquid mixed state exits the indoor unit 2 and flows into the decompression device 74 via the outdoor unit 6 and expands due to the decompression to become 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 outdoor air, becomes a gas refrigerant, and returns to the compressor 75.

  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. In this way, the amount of frost formation in the outdoor heat exchanger 73 continues to increase, the amount of heat pumped up from the outdoor air by the air conditioner 1 decreases, the heating capacity also decreases, and the room cannot be sufficiently heated. Will be lost, so defrosting operation is required.

  Next, defrosting / heating operation in the heating cycle will be described with reference to FIGS. 5 shows the first heat exchanger, FIG. 6 shows the second heat exchanger, FIG. 7 shows the third heat exchanger, and FIG. 8 shows the refrigerant flow when the fourth heat exchanger is defrosted. It is a refrigeration cycle diagram.

  As described above, during the heating operation, 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 falls below a 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 defrosting operation is performed while the heating cycle is performed. I do. 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 simultaneously. Form a frost / 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 arrow in FIG. 5, enters the indoor heat exchanger 33, exchanges heat with the indoor air, and is condensed to become a refrigerant of liquid or gas-liquid mixture. At this time, the room is heated. The refrigerant that has become the liquid or gas-liquid mixed refrigerant exits the indoor unit 2 and flows into the decompression device 74 via the outdoor unit 6 and expands due to the 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 located on the lower side that acts as an evaporator, and initially the second heat exchanger 732 and the third heat exchanger 732. It flows down while melting the frost of the heat exchanger 733 and the fourth heat exchanger 734, becomes lower temperature as it flows down, and re-freezes at the end when the outside air temperature is low.

  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. -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. The defrosting operation of the first heat exchanger 731 is performed for a predetermined time or when 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.

  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, 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 and the second bypass on / off valve 715b is opened to condense the second heat exchanger 732 in the outdoor heat exchanger 73. 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 until the pressure is reduced by the pressure reducing 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. 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. Enters the first heat exchanger 731, the third heat exchanger 733, and the fourth heat exchanger 734 of the outdoor heat exchanger 73 to be heated and exchanged heat with outdoor air, and becomes a gas refrigerant. 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 defrosted from the second heat exchanger 732 is 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 third heat exchanger 733 is defrosted.

  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, the fourth main circuit on-off valve 713d are opened, the third main circuit on-off valve 713c is closed, The first bypass switching valve 715a, the second bypass switching valve 715b, and the fourth bypass switching valve 715d are closed, the third bypass switching 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 from which the frost of the third heat exchanger 733 has been defrosted is the refrigerant 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 fourth heat exchanger 734 is defrosted.

  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, 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, 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. It enters the first heat exchanger 731, the second heat exchanger 732, and the third heat exchanger 733 of the outdoor heat exchanger 73, and is heated by exchanging heat with the outdoor air and becomes a gas refrigerant. 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 when the refrigerant leaves 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 / 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 defrosted water that has flowed from the upper part passes through the lower part of the outdoor heat exchanger 73, defrosting with the melted water is performed. Therefore, when the defrosting of the outdoor heat exchanger 73 is performed, the defrosting is performed from the upper side in the order of the first heat exchanger 731, the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734. 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 is allowed to flow through the refrigerant circuit on the upper side, frost adhering 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.

  The air conditioner of the present invention of this embodiment includes a compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, a refrigerating cycle in which a plurality of outdoor heat exchangers connected in parallel and having different sizes are sequentially connected by a refrigerant pipe, A hot gas bypass circuit branched between the discharge side of the compressor and the four-way valve in the refrigeration cycle and connected between the decompression device and the inlet side during heating operation of each of the plurality of outdoor heat exchangers, In the refrigeration cycle, the refrigerant is circulated in the order of the compressor, the four-way valve, the indoor heat exchanger, the pressure reducing device, the outdoor heat exchanger, and the compressor in the refrigeration cycle, and the bypass circuit. In the defrosting operation in which the compressor, the predetermined outdoor heat exchanger, and the compressor are circulated in the order, and the refrigeration cycle, the refrigerant is supplied to the compressor, the four-way valve, the indoor heat exchanger, the decompression device, and the predetermined outdoor unit. Outdoor heat exchange other than Has heating operation circulates in the order of the compressor, and defrosting and heating mode for performing the in defrosting, the heating operation mode, performing a defrosting operation in order from the small outdoor heat exchanger. If a plurality of outdoor heat exchangers connected in parallel to be defrosted and heated are configured with the same size as in the prior art, outdoor heat exchange is performed while the outdoor heat exchanger is sequentially defrosted. The size of the heat exchanger (outdoor heat exchanger other than the outdoor heat exchanger that performs the defrosting operation) is the same, but since the heat exchange capacity increases, the last heat exchanger is defrosted. Heating capacity will be significantly reduced than during defrosting of the heat exchanger. In the present invention, the fluctuation of the heating capacity is suppressed in consideration of the size of the outdoor heat exchanger that performs the heating operation (the outdoor heat exchanger other than the outdoor heat exchanger that performs the defrosting operation) and the heat exchange capacity of those outdoor heat exchangers. To do. In other words, a plurality of outdoor heat exchangers connected in parallel and having different sizes are provided, and in the defrosting / heating operation mode, the defrosting operation is sequentially performed from the small outdoor heat exchanger, thereby sequentially defrosting the outdoor heat exchangers. During operation, the size of the outdoor heat exchanger for heating operation is gradually reduced, but the heat exchange capacity is gradually increased. Therefore, even during the defrosting / heating operation, fluctuations in the heating capacity can be suppressed, and in particular, the heating capacity can be maintained even while the first heat exchanger in which the heating capacity is greatly reduced is defrosted. As a result, the discomfort of the air conditioner user can be reduced. In addition, in the following present Example, although arrange | positioning upwards in order from a small outdoor heat exchanger, even if it is not necessarily set as such a structure, there can exist the said effect. Moreover, in the following Example, although the outdoor heat exchanger is comprised with three heat exchangers, it is not necessarily limited to three, Two heat exchangers or four or more heat exchangers may be sufficient. .

  Next, the details of the defrosting / heating operation due to the difference in the ratio of the outdoor heat exchangers of the refrigerant circuit divided into a plurality of in the heating cycle of the air conditioner will be described.

  As described above, when the outdoor heat exchanger 73 is defrosted, the first heat exchanger 731 and the second heat exchanger 732 are arranged in order from the top in the heat exchanger 73 of the outdoor heat exchanger of the refrigerant circuit divided into a plurality of sections. The third heat exchanger 733 and the fourth heat exchanger 734 are performed. The defrosting of the first heat exchanger 731 located at the top is performed only with a high-temperature and high-pressure refrigerant, and the frost formed on the second heat exchanger is dissolved to some extent by the flow of molten water in the first heat exchanger 731. The defrosting time is naturally longer than that of the second heat exchanger 732. Similarly for the third heat exchanger 733, the melted water of the first heat exchanger 731 and the second heat exchanger 732, the same for the fourth heat exchanger 734, the first heat exchanger 731, the second heat exchanger 732, and Since the frost is melted to some extent by the molten water of the third heat exchanger 733, the defrosting time of the heat exchanger located on the lower side of the heat exchanger performing the defrosting tends to be short. Therefore, since the outdoor heat exchanger 73 is the same magnitude | size, it cannot be said that the defrosting efficiency of the 1st heat exchanger 731 in which defrosting with a molten water is not performed is favorable compared with others. Further, performing the defrosting operation of the first heat exchanger 731 corresponding to ¼ of the outdoor heat exchanger 73 in a state where the amount of frost formation is increased reduces the heating capacity during the defrosting / heating operation.

  Therefore, the outdoor heat exchange of the refrigerant circuit divided into a plurality of parts by dividing the first heat exchanger 731, the second heat exchanger 732, the third heat exchanger 733, and the fourth heat exchanger 734 of the outdoor heat exchanger 73 into equal parts. The ratio of the heat exchanger below the first heat exchanger 731 that can change the ratio of the heat exchanger, lower the ratio of the first heat exchanger 731 that performs defrosting only with the high-temperature and high-pressure refrigerant, and can use the molten water as the defrost. The defrosting / heating operation for increasing the defrosting efficiency to suppress the reduction of the heating capacity during the defrosting / heating operation will be described with reference to FIG.

  The outdoor heat exchanger 73 in FIG. 9 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 735, a second heat exchanger 736, a third heat exchanger 737, and a fourth heat exchanger 738. When the first heat exchanger 735 is set to 1, the ratio of the outdoor heat exchangers of the refrigerant circuits divided into a plurality is 2, the second heat exchanger 736 is 2, the third heat exchanger 737 is 2, and the fourth heat exchanger is 738 is 3. 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. The operation of the defrosting / heating operation is the same as the outdoor heat exchanger of the refrigerant circuit divided into a plurality of sections described above.

  Here, the first heat exchanger 735 performed only with the high-temperature and high-pressure refrigerant is smaller than the second heat exchanger 736, the third heat exchanger 737, and the fourth heat exchanger 738 on the lower side of the first heat exchanger 735. Thus, the defrosting time is shortened by shortening the refrigerant piping to suppress the temperature drop of the refrigerant and further reducing the area to be defrosted. Therefore, since the temperature of the refrigerant can be kept high, the temperature of the molten water can be kept high, and even if the amount of molten water becomes small by reducing the area to be defrosted, it is on the lower side with a small amount of molten water It is also possible to perform defrosting with the molten water of the second heat exchanger 736. Moreover, the outdoor heat exchanger 73 can also secure the area of the heat exchanger of heating operation by reducing the 1st heat exchanger 735 which defrosts in the state where the amount of frost formation increased and the heating capability fell, and the compressor Since the temperature drop of the refrigerant returning to 75 is also minimal, it is possible to minimize the capacity drop at the time of switching during the defrosting / heating operation. Moreover, the defrosting time of the 1st heat exchanger 735 which defrosts in the state which the amount of frost formation increased and the heating capability fell can be performed in the shortest time. Therefore, the fall of the blowing temperature of an indoor unit by the capability fall at the time of switching from heating operation to defrosting / heating operation can be suppressed.

  The size of the second heat exchanger 736 is also about twice that of the first heat exchanger 735, for example. Since the frost adhering to the heat exchange fin surface is melted to some extent by the molten water having a high temperature of the first heat exchanger 735, defrosting is performed even if the second heat exchanger 736 is larger than the first heat exchanger 735. The time can be finished in a time equivalent to that of the first heat exchanger 735. Moreover, since the defrosting of the 1st heat exchanger 735 is also complete | finished in the capability at the time of a defrost / heating operation, when the area of the heat exchanger of heating operation defrosts the 1st heat exchanger 735 Even if it becomes smaller, the capability reduction can be suppressed. Therefore, the fall of the blowing temperature of an indoor unit by the capability fall of a defrost and heating operation can be suppressed.

  Even if the size of the defrosting of the third heat exchanger 737 is about twice as large as that of the first heat exchanger 735, the surface of the heat exchange fin with the molten water of the first heat exchanger 735 and the second heat exchanger 736. Since the frost attached to the frost is melted to some extent, the defrosting time can be completed in a time equivalent to that of the first heat exchanger 735 even if the third heat exchanger 737 is made larger than the first heat exchanger 735. . Moreover, since the defrosting of the 1st heat exchanger 735 and the 2nd heat exchanger 736 is complete | finished also about the capability at the time of a defrost / heating operation, the area of the heat exchanger of heating operation is the 1st heat exchanger 735. Even if it becomes smaller than when defrosting, it is possible to suppress a decrease in capacity. Therefore, the fall of the blowing temperature of an indoor unit by the capability fall of a defrost and heating operation can be suppressed.

  The defrosting of the fourth heat exchanger 738 is also about three times the size of the first heat exchanger 735, but the first heat exchanger 735, the second heat exchanger 736, and the third heat exchanger 737 are melted. Since the frost adhering to the heat exchange fin surface with water is melted to some extent, even if the fourth heat exchanger 738 is made larger than the first heat exchanger 735, the defrosting time is equal to that of the first heat exchanger 735. Can be finished in time. Moreover, since the defrosting of the 1st heat exchanger 735, the 2nd heat exchanger 736, and the 3rd heat exchanger 737 is complete | finished also about the capability at the time of a defrost / heating operation, the area of the heat exchanger of heating operation Even if it becomes smaller than when defrosting the 1st heat exchanger 735, a capability fall can be suppressed. Therefore, the fall of the blowing temperature of an indoor unit by the capability fall of a defrost and heating operation can be suppressed.

  As described above, the first heat exchanger that performs defrosting only with high-temperature and high-pressure refrigerant is made smaller, and the heat exchanger that can defrost to some extent the frost attached to the heat exchange fin surface with molten water is divided into multiple types. By changing the ratio of the outdoor heat exchanger in the refrigerant circuit and increasing the defrosting efficiency, it is possible to suppress a decrease in capacity during the defrosting / heating operation. Therefore, it is possible to ensure comfort by suppressing a drop in the temperature of the indoor unit.

  (Embodiment 2) In this embodiment, the first main circuit on-off valve 713a, the second main circuit on-off valve 713b, the third main circuit on-off valve 713c, and the fourth main circuit on-off valve during the defrosting / heating operation and the heating operation. The amount of refrigerant flowing to 713d is adjusted from the temperature of the refrigerant temperature detection sensors 811a, 811b, 811c, and 811d so that the cycle temperature of each outdoor heat exchanger serving as an evaporator becomes an appropriate temperature during heating operation. To do. Because of the difference in the size of each outdoor heat exchanger, there are heat exchangers that have excessive or insufficient refrigerant at the same refrigerant flow rate, so the refrigerant corresponding to the size of each outdoor heat exchanger From the temperature of the refrigerant temperature detection sensors 811a, 811b, 811c, 811d to flow, 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 By adjusting the refrigerant flow rate, the efficiency of each outdoor heat exchanger as an evaporator is increased, and the heating performance during defrosting / heating operation and heating operation is improved.

  As described above, according to the air conditioner described in the second embodiment, the efficiency of each outdoor heat exchanger as an evaporator during defrosting / heating operation and heating operation can be increased and the heating performance can be improved. .

  (Embodiment 3) In this embodiment, during the defrosting / heating operation, the rotational speed of the outdoor fan 631 is reduced more than during the heating operation, and when the outside air temperature is lower than a predetermined value, the outdoor blower is used during the defrosting / heating operation. Stop driving. By reducing the rotational speed of the outdoor fan 631 during the defrosting / heating operation, the amount of heat taken away to the outside air by forced convection by the outdoor fan 631 from the melt water, the refrigerant piping, and the heat exchange fin during the defrosting / heating operation is reduced. The frost is efficiently melted. 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. 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 defrosting of the outdoor heat exchanger proceeds efficiently.

  As described above, according to the air conditioner described in the second embodiment, the defrosting / heating operation time can be shortened, and the remaining air is not generated in the defrosting / heating operation even at a low outside air temperature. The comfort of the machine can be improved.

  (Embodiment 4) In this embodiment, the discharge temperature of the compressor 75 is controlled so as to increase the pressure of the decompressor and the compressor speed as the outside air temperature decreases during the heating operation. As a result, the amount of heat stored in the compressor 75 increases, and defrosting with a high-temperature refrigerant is performed during the defrosting / heating operation, and the defrosting / heating operation time is shortened so that the compression when returning to the heating operation is performed. The recovery of the discharge temperature of the machine 75 is accelerated, and the time for the heating capacity to decrease is shortened.

  As described above, according to the air conditioner described in the third embodiment, the defrosting / heating operation time can be shortened, and the comfort of the air conditioner can be improved by reducing the heating capacity.

  (Embodiment 5) In this embodiment, the four-way valve 72 is switched when the temperature of the outdoor unit 6 does not reach a predetermined value even if the defrosting / heating operation is performed until the longest defrosting / heating operation time is reached. Reverse cycle defrosting operation. As a result, the residual frost in the vicinity of the refrigerant circuit outlet of the outdoor heat exchanger 73 (outdoor heat exchanger inlet during cooling) that could not be thawed by the defrosting / heating operation is also restored by performing the reverse cycle defrosting operation. It can be melted with a high-temperature and high-pressure refrigerant from 75.

  As described above, according to the outdoor unit of the air conditioner described in the fourth embodiment, the residual frost near the refrigerant circuit outlet of the outdoor heat exchanger 73 that could not be thawed by the defrosting / heating operation can be melted. It is possible to prevent the heating capacity from being lowered due to residual frost and to improve the comfort of the air conditioner.

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 DESCRIPTION OF SYMBOLS ... Pressure reducing device, 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 ... User side gas Pipe, 713 ... Liquid pipe, 713a ... First main circuit on / off valve, 713b ... Second main circuit on / off valve, 713a ... Third main circuit on / off valve, 713d ... Fourth main circuit on / off valve, 714 ... Heat source side gas pipe, 715 ... Hot gas bypass pipe, 715a ... First bypass on-off valve, 715b ... Second bypass on-off valve, 715c ... Third bypass on-off valve, 715d ... Fourth bypass on-off valve, 716a ... First main circuit / bypass Common pipe, 716b ... second main circuit / bypass common pipe, 716c ... third main circuit / bypass common pipe, 716d ... fourth main circuit / bypass common pipe, 731 ... first heat exchanger, 732 ... second heat exchange 733 ... 3rd heat exchanger, 734 ... 4th heat exchanger, 735 ... 1st heat exchanger, 736 ... 2nd heat exchanger, 737 ... 3rd heat exchanger, 738 ... 4th heat exchanger, 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 (5)

A refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, a pressure reducing device, a plurality of outdoor heat exchangers connected in parallel and having different sizes are sequentially connected by a refrigerant pipe;
A hot gas bypass branched between the discharge side of the compressor and the four-way valve in the refrigeration cycle and connected between the decompression device and the inlet side of each of the plurality of outdoor heat exchangers during heating operation Circuit,
An air conditioner comprising:
In the refrigeration cycle, a heating operation mode in which refrigerant is circulated in the order of the compressor, the four-way valve, the indoor heat exchanger, the pressure reducing device, the outdoor heat exchanger, and the compressor;
In the bypass circuit, in the defrosting operation in which the refrigerant is circulated in the order of the compressor, the predetermined outdoor heat exchanger, and the compressor, and in the refrigeration cycle, the refrigerant is the compressor, the four-way valve, the A defrosting / heating mode for performing an indoor heat exchanger, the decompression device, the outdoor heat exchanger other than the predetermined outdoor unit, and a heating operation for circulating the compressor in order.
Have
In the defrosting / heating operation mode, an air conditioner that performs the defrosting operation in order from the outdoor heat exchanger that is always small. In claim 1,
The plurality of outdoor heat exchangers are air conditioners that are arranged from above in order from the smallest outdoor heat exchanger. In claim 1 or 2,
After performing the heating operation mode,
In the defrosting / heating mode, the defrosting operation is performed for all the outdoor heat exchangers in order from the small outdoor heat exchanger,
Thereafter, the air conditioner returns to the heating operation mode. In claim 1 or 2,
After performing the heating operation mode,
In the defrosting / heating mode, the defrosting operation is performed for all the outdoor heat exchangers in order from the small outdoor heat exchanger,
Thereafter, when the refrigerant temperature of the outdoor heat exchanger is equal to or lower than a predetermined value, the defrosting / heating mode is stopped, and in the refrigeration cycle, the refrigerant is supplied to the compressor, the four-way valve, and the outdoor heat exchanger. The cooling operation mode in which the decompressor, the indoor heat exchanger, and the compressor are circulated in this order,
Thereafter, the air conditioner returns to the heating operation mode. In any one of Claims 1 thru | or 3,
An outdoor fan for blowing air to the outdoor heat exchanger;
The air conditioner which makes the rotation speed of the said outdoor ventilation fan in the said defrost and heating mode smaller than the rotation speed of the said outdoor ventilation fan in the said heating mode.