JP2010048506A - Multi-air conditioner - Google Patents

Abstract

【Task】
Even when a plurality of outdoor units are mixed with cooling / heating operation or stopped outdoor units, excessive accumulation of refrigerant in the compressors of some outdoor units is prevented.
[Solution]
The plurality of indoor units 40a to 40d include indoor heat exchangers 41a to 41d and indoor expansion valves 42a to 42d, respectively, and the plurality of outdoor units 10a and 10b include compressors 11a and 11b and check valves 12a, 12b, four-way valves 13a and 13b, outdoor heat exchangers 14a and 14b, and outdoor expansion valves 15a and 15b, respectively. A plurality of indoor units and a plurality of outdoor units are connected by liquid connection pipes 35 and gas connection pipes 36, and open / close mechanisms 16a and 16b are provided between the four-way valve and the compressor suction side, and a plurality of outdoor units are provided. During the heating operation, at least one of the remaining outdoor units closes the open / close mechanism of the stopped outdoor unit, and closes or adjusts the opening degree of the open / close mechanism of the defrosting outdoor unit.
[Selection] Figure 1

Description

  The present invention relates to a multi-type air conditioner in which a plurality of outdoor units are connected. In particular, even when outdoor units in cooling and heating operations or in a stopped state coexist, refrigerant accumulates excessively in the compressors of some outdoor units. The present invention relates to a multi-type air conditioner that prevents the above.

  In a multi-type air conditioner with multiple outdoor units connected, the direction of the four-way valve of all outdoor units during heating operation is such that the compressor discharge side is connected to the gas connection piping and the compressor suction side is connected to the outdoor heat exchanger. Must do so. If even one unit is oriented to connect the compressor suction side to the gas connection pipe, the high-pressure gas flows into the compressor and the refrigerant accumulates. The same applies to the compressor of the outdoor unit that is stopped.

  A normal four-way valve consists of a main body with a pilot valve and a slide valve. When a differential pressure is generated between the high pressure side pipe and the low pressure side pipe while the pilot valve is controlled to switch the refrigerant flow path, the flow path of the refrigerant passing through the four-way valve is switched by sliding the slide valve. If the other outdoor unit starts heating operation with the direction of the four-way valve in the cooling operation, that is, with the compressor discharge side connected to the outdoor heat exchanger and the compressor suction side connected to the gas connection pipe, The refrigerant pressure in the pipe rises and refrigerant enters the compressor suction side. In order to prevent this, for example, Patent Document 1 discloses that a compressor of an all-outdoor unit is operated and includes a four-way valve alignment control unit that controls the four-way valve position in a unified manner so that the directions of all the four-way valves are aligned. Yes.

JP 2001-1333018 A

  However, when there is a stopped outdoor unit, the four-way valve cannot be switched because the stopped outdoor unit has no differential pressure between the high-pressure side piping and the low-pressure side piping of the four-way valve. In the thing of the said patent document 1, when the cooling season ends and it switches to a heating season, even if there exists a room which does not require heating, the pressure difference between a high pressure side piping and a low pressure side piping is ensured, and the direction of a four-way valve is aligned. Therefore, it is necessary to start all the compressors of the outdoor unit that is stopped. Therefore, the heating capacity tends to be excessive while all outdoor units are in operation.

  Moreover, when the outdoor units in the heating operation alternately perform defrosting, the high-pressure refrigerant in the gas pipe is connected to the suction side of the outdoor unit that performs defrosting, and the refrigerant flows. Also in this case, it is necessary to switch the four-way valve at the same time and all the outdoor units enter the defrosting operation. Then, since the defrosting operation is performed all at once even though the amount of frost formation is different for each outdoor heat exchanger, the heat exchanger with a small amount of frost formation is sent to the indoor unit because the frost quickly disappears and starts to radiate heat to the outside air. The heating capacity that should be reduced. If the defrosting operation is terminated early in order to prevent this, frost remains in the heat exchanger with a large amount of frost formation, the heat absorption efficiency of the outdoor heat exchanger is deteriorated, and the efficiency of the refrigeration cycle is also reduced.

  Furthermore, even when the number of connecting pipes connecting the outdoor unit and the indoor unit is three in order to enable simultaneous cooling and heating operation, for example, if a plurality of outdoor units are set to the heating operation and the cooling operation, the outdoor unit on the heating operation side It is necessary to prevent the high-pressure gas refrigerant flowing out from the outdoor unit on the cooling operation side from flowing into the compressor suction side.

  An object of the present invention is that, in a plurality of outdoor units, even when the outdoor unit that performs heating operation and the outdoor unit that performs stop or defrost operation coexist, refrigerant is excessively accumulated in the compressors of some outdoor units. The object is to obtain a multi-type air conditioner that can prevent the above.

  Another object of the present invention is that, in a plurality of outdoor units that are operated simultaneously with cooling and heating, even when an outdoor unit that performs heating operation and an outdoor unit that stops operation or an outdoor unit that performs cooling operation or defrosting operation are mixed, An object of the present invention is to obtain a multi-type air conditioner that can prevent excessive accumulation of refrigerant in the compressor.

  In order to achieve the above object, the present invention includes a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a compressor, a check valve, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve. In a multi-type air conditioner comprising a plurality of outdoor units, a liquid connection pipe and a gas connection pipe connecting the plurality of indoor units and the plurality of outdoor units, the four-way valve and the compressor suction side; An opening / closing mechanism between the two or more outdoor units, and closing the opening / closing mechanism of the stopped outdoor unit among the plurality of outdoor units during heating operation, or While at least one of the plurality of outdoor units is in a heating operation, the opening / closing mechanism of the outdoor unit performing a defrosting operation among the plurality of outdoor units is closed or the opening degree is adjusted.

  Further, as another feature, a plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a plurality of outdoor units having a compressor, a check valve, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve A liquid connection pipe, a low pressure gas connection pipe and a high pressure gas connection pipe connecting the plurality of indoor units and the plurality of outdoor units, and between the plurality of outdoor units and the plurality of indoor units. In a multi-type air conditioner that is arranged and includes a cooling / heating switching unit that switches connection with the plurality of indoor units so as to connect to either the low-pressure gas connection pipe or the high-pressure gas connection pipe, the four-way valve and the An open / close mechanism is provided between the compressor intake side, the low pressure gas connection pipe is connected between the open / close mechanism and the compressor intake side, and at least one of the plurality of outdoor units is in a heating operation. And cooling operation among the plurality of outdoor units. Closing the open / close mechanism of the outdoor unit that is stopped and the stopped outdoor unit, or performing defrosting operation of the plurality of outdoor units while at least one of the plurality of outdoor units is in a heating operation. The open / close mechanism of the outdoor unit is closed or the opening degree is adjusted.

  According to the present invention, in a multi-type air conditioner including a plurality of indoor units and a plurality of outdoor units, an opening / closing mechanism is provided between the four-way valve of the outdoor unit and the compressor suction side, and heating operation is performed. When the outdoor unit and stop outdoor unit are mixed, the open / close mechanism of the stop outdoor unit is closed.When the outdoor unit performing heating operation and the outdoor unit performing defrost operation are mixed, the open / close mechanism of the outdoor unit performing defrost operation is closed or closed. Since the opening degree is adjusted, even if the high-pressure gas refrigerant that flows out of the outdoor unit that is in heating operation flows into the compressor suction side of the outdoor unit that is stopped or defrosted, Since the flow rate is controlled, it is possible to prevent refrigerant from accumulating in the compressor of the outdoor unit that is stopped or defrosting.

  Further, according to the present invention, in a multi-type air conditioner that operates simultaneously with cooling and heating, when an outdoor unit that performs heating operation and a stopped outdoor unit or an outdoor unit that performs cooling operation coexist, the opening / closing mechanism of the cooling or stopping outdoor unit is closed. When the outdoor unit that performs the heating operation and the outdoor unit that performs the defrosting operation are mixed, the opening / closing mechanism of the outdoor unit that performs the defrosting operation is closed or the opening degree is adjusted. Even if high-pressure gas refrigerant flows into the compressor suction side of an outdoor unit that is in cooling operation or stopped or defrosted, the flow rate of the refrigerant is controlled by the opening and closing mechanism. It is possible to prevent the refrigerant from collecting in the compressor of the outdoor unit.

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

  FIG. 1 shows a first embodiment of the present invention. FIG. 1 shows an example of a refrigeration cycle, which includes two outdoor units 10a and 10b and four indoor units 40a, 40b, 40c, and 40d. Here, the number of outdoor unit connections may be more than two, and the number of indoor unit connections may be more or less than four.

  First, the overall configuration of FIG. 1 will be described. In the casing of the outdoor unit 10a, as shown in FIG. 1, a compressor 11a that compresses and discharges the refrigerant, a check valve 12a for flowing the refrigerant discharged from the compressor 11a in the discharge direction, and a refrigerant A four-way valve 13a that switches the circulation direction of the refrigerant, an outdoor heat exchanger 14a that exchanges heat between the refrigerant and the outside air, and an outdoor expansion valve 15a that functions as a throttle mechanism are sequentially connected by piping, and the suction side of the compressor 11a An open / close mechanism 16a and an accumulator 17a are connected by piping between the two-way valve 13a. And the outdoor fan 19a which ventilates the outdoor heat exchanger 14a is provided. The outdoor unit 10b has the same configuration as the outdoor unit 10a.

  In the casing of the indoor unit 40a, an indoor heat exchanger 41a that exchanges heat between the refrigerant and room air and an indoor expansion valve 42a are connected by a refrigerant pipe. The indoor units 40b to 40d have the same configuration as the indoor unit 40a.

  A liquid connection pipe 35 and a gas connection pipe 36 are connected to the outdoor units 10a and 10b and the indoor units 40a to 40d, and liquid blocking valves 31a and 31b are connected between the pipes and the outdoor units 10a and 10b, respectively. And gas blocking valves 32a and 32b are provided.

  Here, when only some of the indoor units 40a and 40b are heated and activated during the transition from the cooling season to the heating season, the outdoor unit 10a continues to stop because of partial load, that is, the compressor 11a and the outdoor fan. 19a is stopped and the outdoor expansion valve 15a and the electromagnetic valve 16a are closed. On the other hand, the outdoor unit 10b is started, the compressor 11b and the outdoor fan 19b are operated, and the outdoor expansion valve 15b and the electromagnetic valve 16b are opened.

  Here, the direction of the four-way valves 13a and 13b will be described. When the air conditioner is in cooling operation during the cooling season, both the four-way valves 13a and 13b are connected to the discharge pipes 21a and 21b with the outdoor heat exchangers 14a and 14b, and the four-way valve suction side pipes 23a and 23b are connected to the four-way valve blocking valve. It is in the direction of cooling operation connected to the side pipes 22a and 22b. However, when the four-way valves 13a and 13b are controlled to be the refrigerant flow path during the heating operation and the differential pressure between the discharge pipe 21b and the four-way valve suction side pipe 23b is secured after the compressor 11b is started, the four-way valve 13b. Is switched to the direction of the heating operation state in which the discharge pipe 21b is connected to the four-way valve blocking valve side pipe 22b and the four-way valve suction side pipe 23b is connected to the outdoor heat exchanger 14b. The solid line of the four-way valve 13b in FIG. 1 indicates the direction of this heating operation state. In the following description, the direction of the four-way valve is omitted from the cooling operation side (the state of the solid line of the four-way valve 13a in FIG. 1) and the heating operation side (the state of the solid line of the four-way valve 13b in FIG. 1).

  Next, the flow of the refrigerant will be described. Regarding the outdoor unit 10b in operation, the high-pressure gas refrigerant compressed by the compressor 11b passes through the compressor discharge-side check valve 12b, the discharge pipe 21b, and the four-way valve 13b, and passes through the four-way valve blocking valve side pipe 22b and the gas blocking valve 32b. The gas connection pipe 36 is sent. The gas connection pipe 36 is connected to each of the indoor units 40a to 40d and the outdoor unit 10a, but most of the high-pressure gas refrigerant is sent to the indoor heat exchangers 41a and 41b, exchanges heat with the indoor air, and condenses to the high-pressure liquid. Becomes a refrigerant. Some of them are sent to the indoor heat exchangers 41c and 41d to condense, but the indoor expansion valves 42c and 42d may be slightly opened so that the refrigerant does not accumulate. On the other hand, in the outdoor unit 10a, high-pressure gas refrigerant is accumulated up to the gas blocking valve 32a, the four-way valve blocking valve side pipe 22a, and the four-way valve suction side piping 23a, but the accumulator 17a, which is located earlier than the electromagnetic valve 16a, is closed. There is no accumulation in the compressor 11a. Further, when the pressures of the discharge pipe 21a and the four-way valve suction side pipe 23a or the accumulator inlet pipe 24a at this time are compared, the pressure of the discharge pipe 21a is lower than that of the four-way valve suction side pipe 23a and is equal to the accumulator inlet pipe 24a. That is, since there is no differential pressure between the high-pressure side pipe and the low-pressure side pipe, the four-way valve 13a cannot be switched from the cooling operation side to the heating operation side. By operating the compressor 11a and increasing the pressure of the discharge pipe 21a, the four-way valve 13a can be switched from the cooling operation side to the heating operation side, but the stopped compressor 11a is operated wastefully. Because it is not efficient, it is not implemented. However, once switching to the heating operation side, even if the outdoor unit 10b is operated again and the outdoor unit 10a is stopped, high-pressure gas refrigerant is accumulated up to the gas blocking valve 32a, the four-way valve blocking valve side piping 22a, and the discharge piping 21a. However, since the check valve 12a is provided on the discharge side of the compressor, the refrigerant does not accumulate in the compressor 11a and the accumulator 17a ahead of the check valve 12a. In this case, the outdoor unit 10a may be stopped, and the electromagnetic valve 16a may be opened or closed.

  FIG. 2 shows a second embodiment of the present invention. FIG. 2 shows a cycle configuration equivalent to that in FIG. 1, and parts denoted by the same reference numerals as those in FIG. 1 are identical or corresponding parts. This is an example in which the indoor units 40a, 40b, 40c, and 40d perform heating operation, the outdoor unit 10b switches from heating operation, and the outdoor unit 10a switches from heating operation to defrosting operation. That is, the compressor 11a is operated, the outdoor fan 19a is stopped, the outdoor expansion valve 15a is opened, and the electromagnetic valve 16a is closed or slightly opened. Here, if the refrigerant flow to the compressor suction side is completely cut off, the suction pressure decreases and the heat necessary for defrosting cannot be transported, so the opening of the solenoid valve 16a is slightly opened while watching the suction pressure. It is good to make it. When the solenoid valve 16a is only open / closed and the refrigerant flow rate cannot be adjusted, a bypass solenoid valve 18a may be provided in parallel with the solenoid valve 16a as shown in FIG. In this case, the solenoid valve 16a may be closed and the bypass solenoid valve 18a may be repeatedly opened or closed. Moreover, you may use for the solenoid valve 16a or the bypass solenoid valve 18a what can change a flow volume continuously like an expansion valve.

  Next, the flow of the refrigerant will be described. Regarding the outdoor unit 10b during the heating operation, the high-pressure gas refrigerant compressed by the compressor 11b passes through the compressor discharge-side check valve 12b, the discharge pipe 21b, and the four-way valve 13b, and passes through the four-way valve blocking valve side pipe 22b and the gas blocking valve. 32 b and sent to the gas connection pipe 36. The gas connection pipe 36 is connected to each of the heating operation indoor units 40a to 40d and the outdoor unit 10a, but most of the high-pressure gas refrigerant is sent to the indoor heat exchangers 41a, 41b, 41c, and 41d to exchange heat with room air. Condensate into a high-pressure liquid refrigerant. The remaining high-pressure gas refrigerant is sent to the outdoor unit 10a, and is sent to the gas blocking valve 32a, the four-way valve blocking valve side pipe 22a, and the four-way valve suction side pipe 23a. Here, since the electromagnetic valve 16a is closed, the flow rate of the refrigerant is reduced through the bypass electromagnetic valve 18a to become a low-pressure gas refrigerant, which is sent to the accumulator 17a and the compressor 11a. Here, the opening and closing of the bypass solenoid valve 18a is preferably adjusted so that the compressor suction pressure does not decrease excessively. The low-pressure gas refrigerant sent to the compressor 11a is compressed to become high-temperature and high-pressure gas refrigerant, sent to the outdoor heat exchanger 14a through the discharge pipe 21a and the four-way valve 13a, and condensed while melting frost on the surface of the heat exchanger. It becomes a high-pressure liquid refrigerant. The high-pressure liquid refrigerant condensed in the indoor units 40a to 40d and the outdoor unit 10a is sent to the outdoor unit 10b via the liquid connection pipe 35. Then, it is decompressed and expanded by the outdoor expansion valve 15b, evaporates while exchanging heat with the outdoor air by the outdoor heat exchanger 14b, becomes a low-pressure gas refrigerant, passes through the four-way valve 13b, the electromagnetic valve 16b, and the accumulator 17b, and is compressed again by the compressor 11b. Circulate. Since the outdoor unit 10b absorbs heat from the outdoor air and a heat source for performing defrosting with the outdoor unit 10a can be secured, the defrosting time can be shortened as compared with the case where all the outdoor units perform the defrosting operation all at once. Further, since the gas connection pipe 36 is not pulled to a low pressure unlike the defrosting in the normal reverse cycle, the heating start-up after the defrosting is quick.

  FIG. 3 is a configuration diagram of a refrigeration cycle showing Embodiment 3 of the present invention. In FIG. 3, parts denoted by the same reference numerals as those in FIG. 1 are the same or corresponding parts. In this embodiment, two outdoor units 10a and 10b, four indoor units 40a, 40b, 40c and 40d, cooling / heating switching units 50a, 50b, 50c and 50d, a liquid connection pipe 35, a low pressure gas connection pipe 37, and a high pressure It is composed of a gas connection pipe 38, and the operation state of a plurality of indoor units is such that heating operation, cooling operation, and stop can coexist at the same time. As in FIG. 1, the indoor units 40a and 40b are heating operations, the indoor units 10c and 40d are stopped, the outdoor unit 10a is stopped, and the outdoor unit 10b is a heating operation. The fact that the directions of the four-way valves of the outdoor heat exchanger are not aligned is not limited to the time of transition from the cooling season to the heating season, but the outdoor unit 10a is in the cooling operation or outdoor unit 10b depending on the cooling load and the heating load. Can also occur when heating operation.

  First, the flow of the refrigerant when the outdoor unit 10a is stopped will be described as in FIG. Regarding the outdoor unit 10b in operation, the high-pressure gas refrigerant compressed by the compressor 11b passes through the compressor discharge-side check valve 12b, the discharge pipe 21b, and the four-way valve 13b, and passes through the four-way valve blocking valve side pipe 22b and the gas blocking valve 32b. , And sent to the high-pressure gas connection pipe 38. The high-pressure gas refrigerant is sent to the cooling / heating switching units 50a to 50d. Here, the high pressure side opening / closing mechanisms 52a, 52b of the cooling / heating switching units 50a, 50b connected to the heating operation indoor units 40a, 40b are opened and closed, and the high pressure side opening / closing mechanisms 52c of the cooling / heating switching units 50c, 50d connected to the stopped indoor units 40c, 40d, 52d is closed. For this reason, the high-pressure gas refrigerant is sent only to the indoor units 40a and 40b, exchanges heat with indoor air in the indoor heat exchangers 41a and 41b, and condenses into high-pressure liquid refrigerant. On the other hand, in the stopped outdoor unit 10a, high-pressure gas refrigerant is accumulated up to the gas blocking valve 32a, the four-way valve blocking valve side piping 22a, and the four-way valve suction side piping 23a, but the electromagnetic valve 16a is closed and beyond. The refrigerant does not accumulate in the accumulator 17a, the compressor 11a, and the low-pressure gas outdoor unit piping 34a.

  Next, the case where the cooling load of the indoor unit is increased and the outdoor unit 10a is operated for cooling will be described. For example, when the indoor units 40c and 40d that have been stopped perform a cooling operation, the liquid refrigerant condensed by the indoor units 40a and 40b is used, and at the same time, the liquid refrigerant sent from the outdoor unit 10a is also used for cooling. The low-pressure gas refrigerant depressurized by the indoor expansion valves 42c and 42d and heat-exchanged with the indoor air by the indoor heat exchangers 41c and 41d and evaporated is passed through the low-pressure side opening / closing mechanisms 51c and 51d and the low-pressure gas connection pipe 37 of the cooling / heating switching units 50c and 50d. It is sent to the street outdoor units 10a and 10b. The low-pressure gas refrigerant sent to the outdoor unit 10b is sent to the compressor 11b and compressed to become high-temperature high-pressure gas refrigerant, and is sent to the high-pressure gas connection pipe 38 through the discharge pipe 21b, the four-way valve 13b, and the four-way valve blocking valve side pipe 22b. The heating operation indoor units 40a and 40b are used. On the other hand, the low-pressure gas refrigerant sent to the outdoor unit 10a is compressed by the compressor 11a to become a high-temperature high-pressure gas refrigerant, passes through the discharge pipe 21a and the four-way valve 13a, exchanges heat with the outdoor air in the outdoor heat exchanger 14a, and condenses. It becomes a high-pressure liquid refrigerant. At this time, the outdoor expansion valve 15a is opened and sent to the liquid connection pipe 35 and the cooling operation indoor units 40c and 40d for use. When many of the indoor units are in cooling operation, the outdoor expansion valve 15b of the outdoor unit 10b is closed, and all of the high-pressure liquid refrigerant flowing out of the indoor unit that is in heating operation and the high-pressure liquid refrigerant flowing out of the outdoor unit 10a are used. You may send to the indoor unit in air_conditionaing | cooling operation. As described above, in the cooling / heating simultaneous multi-air conditioner having a plurality of outdoor units, when the operation of the outdoor unit is divided into the cooling operation and the heating operation according to the indoor load, the solenoid valve 16a of the outdoor unit 10a on the cooling operation side is divided. It is possible to realize operation by closing the.

  FIG. 4 is a configuration diagram of a refrigeration cycle showing Example 4 of the present invention, and the portions denoted by the same reference numerals as those in FIG. 3 are the same or corresponding portions. The operation is an example of the case where the indoor units 40a, 40b, 40c, and 40d perform the heating operation, the outdoor unit 10b switches to the heating operation, and the outdoor unit 10a switches from the heating operation to the defrosting operation, as in FIG. That is, the compressor 11a is operated, the outdoor fan 19a is stopped, the outdoor expansion valve 15a is opened, and the electromagnetic valve 16a is closed or slightly opened. The difference from FIG. 2 is that the outdoor units 10 a and 10 b are communicated with the indoor units 40 a to 40 d via low-pressure gas outdoor unit piping 34 a and 34 b and a low-pressure gas connection piping 37. For this reason, even if the solenoid valve 16a is closed and the flow of refrigerant to the compressor suction side is completely cut off, the low pressure gas outdoor unit pipe 34b, the low pressure gas connection pipe 37, the low pressure gas from the outdoor unit 10b on the heating operation side Since the low-pressure gas refrigerant is supplied to the compressor 11a via the outdoor unit internal pipe 34a, the suction pressure does not extremely decrease. If the suction pressure is too low, the opening of the solenoid valve 16a may be slightly opened, or a bypass solenoid valve 18a may be provided in parallel with the solenoid valve 16a as shown in FIG. 2, like an expansion valve. You may use what can change a flow volume continuously.

  Next, the flow of the refrigerant will be described. Regarding the outdoor unit 10b during the heating operation, the high-pressure gas refrigerant compressed by the compressor 11b passes through the compressor discharge-side check valve 12b, the discharge pipe 21b, and the four-way valve 13b, and passes through the four-way valve blocking valve side pipe 22b and the gas blocking valve. 32 b and sent to the high-pressure gas connection pipe 38. This high-pressure gas refrigerant is sent to the indoor heat exchangers 41a, 41b, 41c, 41d of the heating operation indoor units 40a-40d via the cooling / heating switching units 50a, 50b, 50c, 50d, and is condensed by exchanging heat with the indoor air. And becomes a high-pressure liquid refrigerant. On the other hand, the high-pressure gas refrigerant is also connected to the outdoor unit 10a, and the high-pressure gas refrigerant accumulates in the gas blocking valve 32a, the four-way valve blocking valve side pipe 22a, and the four-way valve suction side pipe 23a. Here, since the solenoid valve 16a is basically closed, the high-pressure gas refrigerant is not sent to the compressor 11a. The low-pressure gas refrigerant compressed by the compressor 11a is a part of the low-pressure gas refrigerant sent from the outdoor heat exchanger 14b of the outdoor unit 10b to the compressor 11b. The low-pressure gas outdoor unit internal pipe 34b, the low-pressure gas connection pipe 37, The gas outdoor unit piping 34a and the accumulator 17a are sent to the compressor 11a. The compressed high-temperature and high-pressure gas refrigerant is sent to the outdoor heat exchanger 14a through the discharge pipe 21a and the four-way valve 13a, and is condensed while melting frost on the heat exchange surface to become high-pressure liquid refrigerant. Thus, the high-pressure liquid refrigerant condensed in the indoor units 40a to 40d and the outdoor unit 10a is sent to the outdoor unit 10b through the liquid connection pipe 35. Then, it is decompressed and expanded by the outdoor expansion valve 15b, evaporates while exchanging heat with the outdoor air by the outdoor heat exchanger 14b, and becomes a low-pressure gas refrigerant. A part of the refrigerant passes through the four-way valve 13b and the electromagnetic valve 16b and is sent to the outdoor unit 10a. The remainder passes through the accumulator 17b, is compressed again by the compressor 11b, and circulates.

  Thus, since the heat source for absorbing heat from the outdoor air by the outdoor unit 10b and performing defrosting by the outdoor unit 10a can be secured, the defrosting time is also shorter compared to the case where all the outdoor units perform a defrosting operation all at once. Can be defrosted at appropriate timing. Moreover, since the gas connection pipe 36 (see FIG. 2) is not pulled to a low pressure unlike the defrosting in the normal cycle, the heating starts up quickly after the defrosting, and there is no useless heat dissipation or a decrease in heat absorption efficiency during the defrosting. Efficiency can be improved.

The refrigeration cycle block diagram which shows Example 1 of the multi-type air conditioner of this invention. The refrigeration cycle block diagram which shows Example 2 of the multi type air conditioner of this invention. The refrigeration cycle block diagram which shows Example 3 of the multi type air conditioner of this invention. The refrigeration cycle block diagram which shows Example 4 of the multi type air conditioner of this invention.

Explanation of symbols

10a, 10b Outdoor unit 11a, 11b Compressor 12a, 12b Check valve (compressor discharge side check valve)
13a, 13b Four-way valves 14a, 14b Outdoor heat exchangers 15a, 15b Outdoor expansion valves 16a, 16b Electromagnetic valves (opening / closing mechanism)
17a, 17b Accumulator 18a, 18b Bypass solenoid valve 19a, 19b Outdoor fan 21a, 21b Discharge piping 22a, 22b Four-way valve blocking valve side piping 23a, 23b Four-way valve suction piping 24a, 24b Accumulator inlet piping 31a, 31b Liquid blocking valve 32a 32b Gas stop valve (high pressure gas stop valve)
33a, 33b Low pressure gas blocking valve 34a, 34b Low pressure gas outdoor unit internal pipe 35 Liquid connection pipe 36 Gas connection pipe 37 Low pressure gas connection pipe 38 High pressure gas connection pipe 40a, 40b, 40c, 40d Indoor unit 41a, 41b, 41c, 41d Indoor Heat exchanger 42a, 42b, 42c, 42d Indoor expansion valve 50a, 50b, 50c, 50d Cooling / heating switching unit 51a, 51b, 51c, 51d Low pressure side opening / closing mechanism 52a, 52b, 52c, 52d High pressure side opening / closing mechanism

Claims (2)

A plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a plurality of outdoor units having a compressor, a check valve, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve, the plurality of indoor units In a multi-type air conditioner comprising a liquid connection pipe and a gas connection pipe connecting the plurality of outdoor units,
An open / close mechanism provided between the four-way valve and the compressor suction side, wherein at least one of the plurality of outdoor units is in a heating operation, and the outdoor unit is stopped among the plurality of outdoor units. Closing the opening / closing mechanism, or closing or closing the opening / closing mechanism of the outdoor unit that is defrosting out of the plurality of outdoor units while at least one of the plurality of outdoor units is in the heating operation. Multi-type air conditioner characterized by adjusting the opening. A plurality of indoor units having an indoor heat exchanger and an indoor expansion valve, a plurality of outdoor units having a compressor, a check valve, a four-way valve, an outdoor heat exchanger, and an outdoor expansion valve, the plurality of indoor units A liquid connection pipe, a low-pressure gas connection pipe and a high-pressure gas connection pipe for connecting the plurality of outdoor units and the plurality of outdoor units, and the low-pressure gas connection disposed between the plurality of outdoor units and the plurality of indoor units. In a multi-type air conditioner including a cooling / heating switching unit that switches connection with the plurality of indoor units so as to connect to either piping or the high-pressure gas connection piping,
An opening / closing mechanism is provided between the four-way valve and the compressor suction side, the low-pressure gas connection pipe is connected between the opening / closing mechanism and the compressor suction side, and at least one of the plurality of outdoor units During the heating operation of the stand, closing the open / close mechanism of the outdoor unit that is in cooling operation and the stopped outdoor unit among the plurality of outdoor units, or at least one of the plurality of outdoor units A multi-type air conditioner that closes or adjusts the opening degree of the outdoor unit that is performing a defrosting operation among the plurality of outdoor units while the stand is in a heating operation.

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