JP6727296B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner applied to a building multi air conditioner or the like.

When the air conditioner is operated for heating in winter, water vapor in the air adheres to the heat exchanger on the heat source side to generate frost. If frost remains on the heat exchanger, the heating capacity will decrease.Therefore, normally, defrost operation is performed in the outdoor unit between heating operations to melt the frost adhering to the heat exchanger and stabilize the heating capacity. I am trying to demonstrate it.

When the defrost operation is performed, the frost generated in the heat exchanger melts and becomes defrost water, which is transmitted to the lower part of the heat exchanger. In cold regions, the defrost water temperature is low and the outside air temperature is extremely low.Therefore, when such defrost operation is performed in the air conditioner, when the defrost water is transferred to the lower part of the heat exchanger, It may freeze. Therefore, in order to prevent re-freezing of the defrosted water, a bypass circuit is provided at the bottom of the heat exchanger, and a high-pressure and high-temperature refrigerant is allowed to flow into the bypass circuit (Patent Document 1).

JP, 2008-64381, A

By the way, a plurality of air conditioners for buildings are often used with a plurality of air conditioners. At that time, the outdoor units of the air conditioners are installed side by side, that is, with their side surfaces facing each other. When a plurality of outdoor units are installed in a concentrated manner, the distance between adjacent side surfaces of adjacent devices is only a few centimeters. During the above-mentioned defrost operation, since the blower of the outdoor unit of the air conditioner is stopped, only the outdoor wind passes through the outdoor unit. Therefore, in a multi air conditioner for a building, when a plurality of outdoor units are installed in a concentrated manner as described above, the influence of the outside wind during defrost operation is such that the outdoor units face each other at a slight interval. Larger on the front and back than sides. As a result, the defrosted water is likely to refreeze on the front surface and the rear surface of the outdoor unit.

In addition, the outer shape of the outdoor unit is often a substantially rectangular parallelepiped as a whole, and the influence of outside wind varies depending on the area of each surface. Further, in the above-mentioned bypass circuit, the temperature of the refrigerant farthest from the header of the heat exchanger becomes lower than the temperature of the other parts. Therefore, the temperature of the bypass circuit for preventing re-freezing is not uniform in one heat exchanger, drainage tends to be poor, and re-freezing may be caused depending on the distance from the header.

The present invention has been made to solve the above problems, and in a multi-air conditioner in which a plurality of outdoor units are arranged, improves defrosting efficiency during defrost operation and prevents refreezing of defrosted water. The purpose is to do.

The air conditioner according to the present invention includes a compressor, a flow path switching device, and a plurality of heat source side heat exchangers, an outdoor unit in which these are connected by piping, and the outdoor unit is connected to the outdoor unit. An air conditioner comprising an indoor unit for air conditioning a space, wherein the outdoor unit is connected to a discharge side of the compressor and the other is connected to a suction side of the compressor in a pipe connection of the outdoor unit. A plurality of bypass circuits, wherein a plurality of bypass circuits configured to allow refrigerant to flow into the respective lower portions of the plurality of heat source side heat exchangers during defrost operation of the air conditioner; A flow rate adjusting mechanism that is provided in each of the bypass circuits and that adjusts the flow rate of the refrigerant that flows into the plurality of bypass circuits , a control unit, and a detection unit that detects the ambient temperature of the plurality of heat source side heat exchangers are provided. However, the control means, immediately after the start of the defrost operation of the air conditioner or after a lapse of a set time from the start of the defrost operation, based on the ambient temperature detected by the detection means of each of the plurality of heat source side heat exchangers, The flow rate adjusting mechanism is controlled to adjust the flow rate of the refrigerant flowing into the plurality of bypass circuits .

According to the air conditioner of the present invention, in the plurality of bypass circuits configured to allow the refrigerant to flow into the lower portions of the plurality of heat source side heat exchangers during the defrost operation, the flow rate for adjusting the flow rate of the refrigerant flowing into the bypass circuit. An adjustment mechanism is provided. Therefore, even when the outdoor units are centrally arranged in the multi-air conditioner for buildings, the defrost water generated in the defrost operation is caused by causing each of the flow rate adjustment mechanisms to function according to the arrangement mode of each outdoor unit. It is possible to surely prevent the re-freezing.

It is a schematic diagram of a refrigerant circuit of an air harmony device. It is a figure which shows the flow of the refrigerant at the time of heating operation of an air conditioner. It is a figure showing the flow of the refrigerant at the time of defrost operation of an air harmony device. It is a schematic diagram of a heat source side heat exchanger of an air harmony device. It is a figure which shows the flow of the refrigerant at the time of the defrost operation of an air conditioning apparatus, when the solenoid valve for bypass circuits is opened. It is a figure which shows an example of the intensive installation of the outdoor unit in Embodiment 1 of this invention. It is the schematic of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is a control block diagram of the air conditioning apparatus which concerns on Embodiment 1 of this invention. It is the schematic which shows the heat-source side heat exchanger in Embodiment 2 of this invention from an upper part. It is the schematic of the refrigerant circuit of the air conditioning apparatus which concerns on Embodiment 2 of this invention.

Embodiments of a refrigeration cycle device according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments described below. Further, in the following drawings, the size of each component may be different from the actual device.

FIG. 1 is a schematic diagram of a refrigerant circuit of an air conditioner. In the air conditioner 100, the indoor units 10a, 10b, 10c, and 10d and the outdoor unit (heat source device) 20 are connected by a pipe A and a pipe B. The indoor units 10a, 10b, 10c, 10d are connected in parallel. The pipe A and the pipe B are refrigerant pipes that conduct a refrigerant (heat source side refrigerant).

In the outdoor unit 20, the compressor 1, the flow path switching device 2 such as a four-way valve, the heat source side heat exchangers 3a and 3b, and the accumulator 5 are connected by piping. The compressor 1 sucks in a refrigerant, compresses the refrigerant into a high temperature and high pressure state, and conveys the refrigerant to a refrigerant circuit. The compressor 1 is composed of, for example, a capacity-controllable inverter compressor. The flow path switching device 2 switches the flow of the refrigerant in the heating operation mode and the flow of the refrigerant in the cooling operation mode. The heat source side heat exchangers 3a and 3b function as an evaporator in the heating operation mode, function as a radiator in the cooling operation mode and the defrost operation mode, and supply air from a blower (not shown) such as a fan. Heat exchange with the refrigerant. The heat source side heat exchangers 3a and 3b are connected in parallel in the refrigerant pipe of the outdoor unit 20. The heat source side heat exchangers 3 a and 3 b have an L-shaped outer shape and are arranged so as to form a rectangular frame body as a whole in the housing of the outdoor unit 20. The accumulator 5 is provided on the suction side of the compressor 1 and stores the excess refrigerant due to the difference between the heating operation mode and the cooling operation mode, and the excess refrigerant due to a transient change in operation.

Bypass circuits 6 a and 6 b are connected to the piping of the outdoor unit 20. In the piping of the outdoor unit 20, one of the bypass circuits 6a and 6b is connected to the discharge side of the compressor 1 and the other is connected to the suction side. Further, the bypass circuit 6a is configured to pass through the lower portion of the heat source side heat exchanger 3a, and the bypass circuit 6b is configured to pass through the lower portion of the heat source side heat exchanger 3b. Further, a solenoid valve 4 as an opening/closing means is connected to the bypass circuits 6a and 6b via a pipe. The refrigerant in the pipe does not flow into the bypass circuits 6a and 6b when the solenoid valve 4 is closed, and flows into the bypass circuits 6a and 6b when the solenoid valve 4 is opened. The bypass circuits 6a and 6b and the solenoid valve 4 are used to prevent re-freezing of the melted frost after the air conditioner 100 is defrosted.

In the indoor unit 10a, the use side heat exchanger (indoor side heat exchanger) 12a and the expansion device 11a are connected in series. In the indoor unit 10b, the use side heat exchanger 12b and the expansion device 11b are connected in series. In the indoor unit 10c, the use side heat exchanger 12c and the expansion device 11c are connected in series. In the indoor unit 10d, the use side heat exchanger 12d and the expansion device 11d are connected in series. The utilization side heat exchangers 12a, 12b, 12c, 12d function as a condenser in the heating operation mode and as an evaporator in the cooling operation mode, and are provided between the air and the refrigerant supplied by a blower (not shown) such as a fan. Heat exchange is performed to generate cooling air or heating air to be supplied to the air-conditioned space. The expansion devices 11a, 11b, 11c, and 11d have a function as a pressure reducing valve or an expansion valve, and decompress the refrigerant to expand it. For example, an electronic expansion valve whose opening can be variably controlled. Composed of. In the air conditioner 100, four indoor units 10a, 10b, 10c, 10d are connected in parallel, but this is an example, and the number of indoor units is not limited to four.

Here, each operation mode executed in the air conditioner 100 will be described.

[Heating operation mode]
FIG. 2 is a diagram showing the flow of the refrigerant during the heating operation of the air conditioner. In FIG. 2, the flow of the refrigerant during the heating operation is indicated by an arrow. A case where all the indoor units 10a, 10b, 10c, and 10d are driven will be described with reference to FIG. When the low-temperature low-pressure gas refrigerant is sucked into the compressor 1, the low-temperature low-pressure gas refrigerant is compressed by the compressor 1, becomes high-temperature high-pressure gas refrigerant, and is discharged from the compressor 1. The gas refrigerant discharged from the compressor 1 flows out of the outdoor unit 20 via the flow path switching device 2 and the pipe A, and flows into the use side heat exchangers 12a, 12b, 12c, 12d.

The high-temperature and high-pressure gas refrigerant that has flowed into the use side heat exchangers 12a, 12b, 12c, 12d becomes a liquid refrigerant by exchanging heat with the air supplied from a blower (not shown). The utilization side heat exchangers 12a, 12b, 12c, 12d function as condensers that radiate heat to the ambient air and lower the refrigerant temperature in the heat exchanger pipes. The high-temperature high-pressure liquid refrigerant flowing out from the use side heat exchangers 12a, 12b, 12c, 12d is expanded and decompressed by the expansion devices 11a, 11b, 11c, 11d to become low-temperature low-pressure gas-liquid two-phase refrigerant, and the indoor unit 10a. 10b, 10c, 10d. The refrigerant flowing out from the indoor units 10a, 10b, 10c, 10d flows into the outdoor unit 20 through the pipe B. The gas-liquid two-phase refrigerant that has flowed into the outdoor unit 20 exchanges heat with the air supplied by the blower (not shown) in the heat source side heat exchangers 3a and 3b to become a low-temperature low-pressure gas refrigerant. The heat source side heat exchangers 3a and 3b function as evaporators that absorb heat from the ambient air and evaporate the refrigerant in the pipes. The gas refrigerant flowing out from the heat source side heat exchangers 3a and 3b flows into the accumulator 5 through the pipe in the outdoor unit 20 and the flow path switching device 2. The refrigerant flowing into the accumulator 5 is separated into a liquid refrigerant and a gas refrigerant, and the gas refrigerant is sucked into the compressor 1 again.

When the heating operation is continuously performed (evaporation temperature is 0° C. or less) under a low outside air temperature, the surfaces of the heat source side heat exchangers 3a and 3b are frosted. Moisture contained in the air that is heat-exchanged in the heat source side heat exchangers 3a and 3b is condensed on the surface of the heat source side heat exchangers 3a and 3b functioning as an evaporator, and frost is generated because the outside air temperature is low. This is because. When the amount of frost in the heat source side heat exchangers 3a, 3b increases, the thermal resistance increases and the air volume decreases, so that the pipe temperature (evaporation temperature) in the heat source side heat exchangers 3a, 3b decreases, and the heating capacity increases. Can not be fully exerted. Therefore, it is necessary to perform defrost to defrost.

[Defrost operation mode]
FIG. 3 is a diagram showing the flow of the refrigerant during the defrost operation of the air conditioner. In FIG. 3, the flow of the refrigerant in the defrost operation mode is indicated by an arrow. In the defrost operation mode, the normal heating operation is interrupted, and the circulation direction of the refrigerant is switched to the same circulation direction as in the cooling operation mode by the flow path switching device 2. When the low-temperature low-pressure gas refrigerant is sucked into the compressor 1, the low-temperature low-pressure gas refrigerant is compressed by the compressor 1, becomes a high-temperature high-pressure gas refrigerant, and is discharged from the compressor 1. The gas refrigerant discharged from the compressor 1 passes through the flow path switching device 2 and flows into the heat source side heat exchangers 3a and 3b. The high-temperature and high-pressure gas refrigerant that has flowed into the heat source side heat exchangers 3a and 3b becomes a liquid refrigerant by exchanging heat with the surrounding air. The heat source side heat exchangers 3a and 3b function as condensers that radiate heat to the ambient air and lower the refrigerant temperature in the pipes. Therefore, the frost adhered to the surfaces of the heat source side heat exchangers 3a and 3b is melted by the heat radiation of the heat source side heat exchangers 3a and 3b into the air. At this time, the blower (not shown) arranged near the heat source side heat exchangers 3a and 3b is often stopped. The liquid refrigerant flowing out of the heat source side heat exchangers 3a, 3b flows through the pipe B into the indoor units 10a, 10b, 10c, 10d.

The liquid refrigerant that has flowed into the indoor units 10a, 10b, 10c, and 10d is expanded and depressurized by the expansion devices 11a, 11b, 11c, and 11d to become a low-temperature low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows out of the indoor units 10a, 10b, 10c, 10d without being heat-exchanged in the use side heat exchangers 12a, 12b, 12c, 12d. The gas-liquid two-phase refrigerant flowing out from the indoor units 10a, 10b, 10c, 10d passes through the pipe A and flows into the outdoor unit 20 again. The gas-liquid two-phase refrigerant that has flowed into the outdoor unit 20 passes through the flow path switching device 2 and flows into the accumulator 5. The refrigerant flowing into the accumulator 5 is separated into a liquid refrigerant and a gas refrigerant, and the gas refrigerant is sucked into the compressor 1 again.

[During defrost operation]
FIG. 4 is a schematic diagram of a heat source side heat exchanger of the air conditioner. FIG. 4 shows a side view of the heat source side heat exchanger 3a. FIG. 5: is a figure which shows the flow of a refrigerant at the time of the defrost operation of an air conditioning apparatus, when the solenoid valve for bypass circuits is opened. The heat source side heat exchanger 3a has a structure in which a plurality of hairpin-bent heat transfer tubes are vertically inserted into a plurality of fins. The bypass circuit 6a is arranged below the heat source side heat exchanger 3a. Since the heat source side heat exchanger 3a is long in the stage direction, there is a concern that defrosting water may accumulate in the portion where the bypass circuit 6a is arranged after the defrost operation and re-freezing. Therefore, as shown in FIG. 5, the solenoid valve 4 is opened during the defrosting operation or at the end of the defrosting operation to allow the refrigerant in the pipe to flow into the bypass circuit 6a. As described above, during the defrost operation, the refrigerant in the pipe of the outdoor unit 20 is in a high temperature and high pressure state. Therefore, by flowing the refrigerant into the bypass circuit 6a, it is possible to enhance the heating of the lower portion of the heat source side heat exchanger 3a. As a result, re-freezing of frost in the lower part of the heat source side heat exchanger 3a is prevented. Similarly, the bypass circuit 6b is arranged below the heat source side heat exchanger 3b, and the solenoid valve 4 is connected thereto. Therefore, by opening the solenoid valve 4 at the final stage of the defrost operation, the high temperature and high pressure refrigerant flows into the bypass circuit 6b, and re-freezing of frost in the lower portion is prevented.

In the defrost operation, all the frost adhering to the heat source side heat exchangers 3a and 3b is usually melted based on the detection result of the temperature detecting means (not shown) installed in the heat source side heat exchangers 3a and 3b. If it is confirmed that it has finished, it will be terminated. When the defrost operation ends, the flow path switching device 2 is switched, and the above heating operation is resumed. The end of the defrost operation is determined by, for example, confirming the rise in the pipe temperature of the heat source side heat exchangers 3a and 3b due to the removal of all frost.

In order to prevent re-freezing of frost after the defrosting operation, the air conditioner 100 having a configuration in which the refrigerant is circulated by using the bypass circuits 6a and 6b as shown in FIG. 5 has to consider the influence of the installation environment. It may not happen. Since the multi air conditioner for buildings is used in a large-scale building or facility due to its use, a large number of outdoor units are often installed on the rooftop. In this specification, the installation of the outdoor unit in such a building multi-air conditioner is referred to as centralized installation.

FIG. 6 is a diagram showing an example of centralized installation of outdoor units according to Embodiment 1 of the present invention. FIG. 6A is a diagram showing a mode of centralized installation from the side surface of the outdoor unit, and FIGS. 6B to 6E are diagrams showing a mode of centralized installation from the upper surface of the outdoor unit. In FIGS. 6B to 6E, it is assumed that the front surface of each indoor unit faces the upper side of the paper surface and the back surface faces the lower side of the paper surface. Further, in these figures, the arrow indicates the direction of the wind.

As shown in FIG. 6A, in centralized installation, the left and right installation intervals between outdoor units are often very narrow. In an outdoor unit in which other outdoor units are arranged on both side faces, the side faces of the adjacent outdoor units are adjacent to the side faces, while the front face and the back face are always exposed to the outside air. Also, in the outdoor units located at both ends of the central installation, the side face of the adjacent outdoor unit is adjacent to the side face on the side where the outdoor unit is located next to it, while the outdoor unit is placed next to it. The side, front and back of the unopened side are always exposed to the atmosphere. Therefore, the influence of the wind on each outdoor device differs depending on the direction of the wind of the outside air.

For example, when the wind flows as shown in FIG. 6B, each outdoor unit is more affected by the wind on the front side than the other faces, and when the wind hits as shown in FIG. 6C, each outdoor unit is affected. Is more affected by the wind on the back surface than on other surfaces. Further, when the wind flows as shown in FIG. 6D, the outdoor unit arranged at the left end in the figure is more affected by the wind on the left side surface than the other surfaces and the other outdoor units. When the wind flows as in e), the outdoor unit arranged at the right end in the figure is more affected by the wind on the right side surface than on the other surfaces and the other outdoor units.

Normally, when the air conditioner is in the cooling operation or the heating operation, the blower is operated to force the air to pass through the heat source side heat exchanger, but in the defrost operation, the blower of the outdoor unit is stopped. During defrost operation, when the wind flows as shown in FIG. 6(b), more outside air hits the front surface than the other surface of the outdoor unit, and when the wind flows as shown in 6(c), the other surface of the outdoor unit. A lot of outside air hits the back side. Further, when the wind flows as shown in FIG. 6D during the defrost operation, the left side surface of the outdoor unit arranged at the left end in the figure is separated from the other side surface of the outdoor unit and each surface of the other outdoor unit. When a large amount of outside air hits and the wind flows as shown in FIG. 6(e), the other side surface of the outdoor unit and each surface of the other outdoor unit are attached to the right side surface of the outdoor unit arranged at the right end in the figure. More outside air hits.

In the case of forced convection, the 0.5th power of the wind speed is proportional to the thermal conductivity, so that when the wind speed becomes A times, the heat radiation amount becomes √A times. Therefore, in the defrost operation mode, when the wind flows as shown in FIG. 6(b) or 6(c), the amount of heat radiation is increased at the front surface or the back surface of the outdoor unit and the heat is taken away. There is a high possibility that the defrost water generated by the defrost operation will be frozen again. Further, when the wind flows as shown in FIG. 6D, the heat radiation amount on the left side surface of the outdoor unit arranged at the left end in the figure is released on the other side surface of the outdoor unit and each surface of the other outdoor unit. Since the amount of heat becomes larger than the amount of heat and the heat is taken away, there is a high possibility that the defrost water generated by the defrost operation will be re-iced on the left side surface of the outdoor unit arranged at the left end. Further, when the wind flows as shown in FIG. 6(e), the amount of heat radiation on the right side surface of the outdoor unit arranged at the right end in the figure is released on the other side surface of the outdoor unit and each surface of the other outdoor unit. Since the amount of heat becomes larger than the amount of heat and the heat is taken away, there is a high possibility that the defrost water generated by the defrost operation will be re-iced on the right side surface of the outdoor unit arranged at the right end.

Embodiment 1.
FIG. 7 is a schematic diagram of a refrigerant circuit of the air-conditioning apparatus according to Embodiment 1 of the present invention. The same components as those of the refrigerant circuit shown in FIGS. 1 to 3 described above are designated by the same reference numerals, and description thereof will be omitted here. In the air conditioner 200 of Embodiment 1, the bypass circuit 6a is provided with an electronic expansion valve 7a as a flow rate adjusting mechanism and a thermistor 8a as a temperature detecting means. The electronic expansion valve 7a and the thermistor 8a are provided on the secondary side of the bypass circuit 6a via the heat source side heat exchanger 3a. Similarly, the bypass circuit 6b is provided with an electronic expansion valve 7b as a flow rate adjusting mechanism and a thermistor 8b as a temperature detecting means. The electronic expansion valve 7b and the thermistor 8b are provided on the secondary side of the bypass circuit 6b via the heat source side heat exchanger 3b. The heat source side heat exchanger 3a is provided with a temperature sensor 9a for detecting the outlet temperature of the outlet through which the refrigerant flows, and the heat source side heat exchanger 3b has a temperature for detecting the outlet temperature of the outlet through which the refrigerant flows. A sensor 9b is provided.

When the solenoid valve 4 is opened and the electronic expansion valve 7a reaches a predetermined opening degree, the high-temperature and high-pressure gas refrigerant starts flowing into the bypass circuit 6a. The gas refrigerant flowing into the bypass circuit 6a is heat-exchanged with the defrost water in the lower part of the heat source side heat exchanger 3a. As a result, the high-temperature and high-pressure gas refrigerant heats the bypass circuit 6a of the heat source side heat exchanger 3a while changing to a liquid state, so that re-freezing of defrost water is prevented. When the solenoid valve 4 is opened and the electronic expansion valve 7b has a predetermined opening degree, the high-temperature and high-pressure gas refrigerant starts flowing into the bypass circuit 6b. The gas refrigerant flowing into the bypass circuit 6b is heat-exchanged with the defrost water in the lower part of the heat source side heat exchanger 3b. As a result, the high-temperature and high-pressure gas refrigerant heats the bypass circuit 6b of the heat source side heat exchanger 3b while changing to a liquid state, so that re-freezing of defrost water is prevented.

FIG. 8 is a control block diagram of the air conditioner 200. The controller 201 controls the entire air conditioning apparatus 200. The temperature sensor 9a, the temperature sensor 9b, the thermistor 8a, and the thermistor 8b are connected to the controller 201. Further, the controller 201 is connected to the solenoid valve 4, the electronic expansion valve 7a, and the electronic expansion valve 7b. When the outlet temperature of the heat source side heat exchanger 3a detected by the temperature sensor 9a becomes equal to or higher than a predetermined temperature immediately after the start of the defrost operation or after a preset time has elapsed from the start of the defrost operation, the controller 201 determines that the solenoid valve 4 Is output to the solenoid valve 4. The controller 201 also detects the temperature of the thermistor 8a, determines the opening degree of the electronic expansion valve 7a, and outputs a control signal based on the result to the electronic expansion valve 7a. Similarly, the controller 201 outputs a signal for opening the solenoid valve 4 to the solenoid valve 4 when the outlet temperature of the heat source side heat exchanger 3b detected by the temperature sensor 9b becomes equal to or higher than a predetermined temperature. Further, the controller 201 detects the temperature of the thermistor 8b, determines the opening degree of the electronic expansion valve 7b, and outputs a control signal based on the result to the electronic expansion valve 7b. Specifically, the opening degrees of the electronic expansion valves 7a and 7b are determined based on the difference (ΔT=T ^* −T) between the target temperature T ^* and the detected temperature T of the thermistors 8a and 8b. The controller 201 outputs a control signal for increasing the opening degree of the electronic expansion valves 7a, 7b when ΔT>0, and a control signal for decreasing the opening degree of the electronic expansion valves 7a, 7b when ΔT<0. Is output.

As described above, according to the first embodiment, in addition to the opening control of the solenoid valve 4, the opening control of the electronic expansion valves 7a and 7b based on the detection results of the thermistors 8a and 8b is performed, and the bypass circuit 6a is performed. , 6b is adjusted according to the surrounding environment of the heat source side heat exchangers 3a, 3b. In other words, the defrost capability of the heat source side heat exchangers 3a and 3b is adjusted according to the surrounding environment. Therefore, the refrigerant flow rate to the bypass circuits 6a and 6b can be optimized according to the defrost load of the bypass circuits 6a and 6b. As a result, as described with reference to FIGS. 6A to 6E, the wind of the outside air on each surface of the heat source side heat exchangers 3a and 3b is caused by the arrangement position of the outdoor unit in the centralized installation. Even if there is a difference in the effect of, the re-freezing of the defrosted water can be surely prevented according to the degree of each effect.

Embodiment 2.
FIG. 10 is a schematic diagram of the refrigerant circuit of the air-conditioning apparatus according to Embodiment 2 of the present invention. The same components as those of the refrigerant circuit shown in FIGS. 1 to 3 described above are designated by the same reference numerals, and description thereof will be omitted here. In the air-conditioning apparatus 300 of Embodiment 2, the bypass circuit 6a is provided with the pipe resistance 15a, and the bypass circuit 6b is provided with the pipe resistance 15b. The piping resistors 15a and 15b are, for example, capillaries (capillary tubes). The amount of refrigerant flowing into the bypass circuit 6a is determined by the pipe resistance 15a, and the amount of refrigerant flowing into the bypass circuit 6b is determined by the pipe resistance 15b. The flow resistances of the refrigerant of the piping resistance 15a and the piping resistance 15b are different so that the flow rates of the refrigerant to the bypass circuits 6a and 6b are different.

Here, the environment in which a plurality of outdoor units 20 are centrally installed in a multi air conditioner for a building will be described as an example in which the direction of the wind of the outside air is the direction shown in FIG. 6B or 6C. To do. FIG. 9 is a schematic view showing a heat source side heat exchanger according to the second embodiment of the present invention from above. The L-shaped heat source side heat exchangers 3a and 3b are arranged in the housing of the outdoor unit 20 so as to form a substantially rectangular frame body when viewed from above, and the heat source side heat exchanger 3a is located on the front side of the outdoor unit 20. It is located at. In FIG. 9, the front of the outdoor unit 20 faces the lower side of the paper surface. In FIG. 9, an inlet 13a and an outlet 13b are respectively an inlet and an outlet of the bypass circuit 6a of the heat source side heat exchanger 3a, and an inlet 14a and an outlet 14b are respectively an inlet of the bypass circuit 6b of the heat source side heat exchanger 3b. It is the exit. When the direction of the wind of the outside air is as shown in FIG. 6(b) or FIG. 6(c), the surface 16a of the heat source side heat exchanger 3a is a surface on which the heat source side heat exchanger 3a receives the wind. The surface 16b of the side heat exchanger 3a is a surface on which the heat source side heat exchanger 3b receives wind.

The inlet 13a of the bypass circuit 6a of the heat source side heat exchanger 3a is located on the side of the wind-receiving surface 16a, and the refrigerant gas has a high temperature at the site of the wind receiving surface 16a of the heat source-side heat exchanger 3a. It flows in the state. On the other hand, the inlet 14a of the bypass circuit 6b of the heat source side heat exchanger 3b is located on the side of the side surface that intersects the wind receiving surface 16b, and the refrigerant gas passes through the side surface portion of the heat source side heat exchanger 3b. , Flows into the part of the surface 16b that receives the wind. Therefore, the temperature of the refrigerant gas flowing into the portion of the surface 16b of the heat source side heat exchanger 3b is lower than the temperature of the refrigerant gas flowing into the portion of the surface 16a of the heat source side heat exchanger 3a. Therefore, the defrost ability of the heat source side heat exchanger 3b must be made larger than the defrost ability of the heat source side heat exchanger 3a. In the second embodiment, the flow resistance of the pipe resistance 15b is smaller than the flow resistance of the pipe resistance 15a.

As described above, in the second embodiment, in the centralized installation of the multi-air conditioning system for buildings, the magnitude of the defrost capacity required for each of the heat source side heat exchanger 3a and the heat source side heat exchanger 3b of the outdoor unit 20 is known. In this case, the piping resistance 15a and the piping resistance 15b are set so that the flow resistance is set according to the required defrosting ability.

According to the second embodiment, an increase in the number of parts can be suppressed. Therefore, in the centralized installation, when the magnitude of the defrosting ability required in advance depending on the arrangement position is known, it is possible to prevent re-freezing of defrost water in the heat source side heat exchangers 3a and 3b while suppressing the product cost. it can.

1 compressor, 2 flow path switching device, 3a heat source side heat exchanger, 3b heat source side heat exchanger, 4 solenoid valve, 5 accumulator, 6a bypass circuit, 6b bypass circuit, 7a electronic expansion valve, 7b electronic expansion Valve, 8a thermistor, 8b thermistor, 9a temperature sensor, 9b temperature sensor, 10a indoor unit, 10b indoor unit, 10c indoor unit, 10d indoor unit, 11a throttling device, 11b throttling device, 11c throttling device, 11d throttling device, 12a use Side heat exchanger, 12b utilization side heat exchanger, 12c utilization side heat exchanger, 12d utilization side heat exchanger, 13a inlet, 13b outlet, 14a inlet, 14b outlet, 15a piping resistance, 15b piping resistance, 16a surface, 16b Surface, 20 outdoor unit, 100 air conditioner, 200 air conditioner, 201 controller, 300 air conditioner.

Claims (2)

A compressor, a flow path switching device, and a plurality of heat-source-side heat exchangers, an outdoor unit in which these are connected by piping, and an indoor unit that is connected to the outdoor unit and performs air conditioning of the target space. An air conditioner equipped with,
The outdoor unit is
In the piping connection of the outdoor unit, one is a plurality of bypass circuits connected to the discharge side of the compressor and the other is connected to the suction side of the compressor, the plurality of bypass circuits during defrost operation of the air conditioner. A plurality of bypass circuits configured so that the refrigerant flows into the lower part of each of the heat source side heat exchangers,
A flow rate adjusting mechanism that is provided in each of the plurality of bypass circuits and adjusts the flow rate of the refrigerant flowing into the plurality of bypass circuits,
Control means,
A detection means for detecting the ambient temperature of the plurality of heat source side heat exchangers,
The control means adjusts the flow rate based on the ambient temperature detected by the detection means of each of the plurality of heat source side heat exchangers immediately after the start of the defrost operation of the air conditioner or after a lapse of a set time from the start of the defrost operation. An air conditioner that controls a mechanism to adjust the flow rate of the refrigerant flowing into the plurality of bypass circuits. The air conditioner according to claim 1, wherein the flow rate adjusting mechanism is an electronic expansion valve, and the control unit adjusts an opening degree of the electronic expansion valve.

Images