JP2003176959A - Air conditioner, and outdoor heat exchanger switching control method for air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch an outdoor heat exchanger corresponding to the change of the cooling heating load of an indoor unit while keeping the amenity of the air conditioner. <P>SOLUTION: In this air conditioner where two or more indoor units 5a, 5b can be simultaneously operated for cooling or heating, or the cooling operation and the heating operation can be performed in a mixed state, one end of each outdoor heat exchanger 3a, 3b of the outdoor unit 1 and a suction pipe 8 of a compressor 2 are connected by a bypass pipe 35 provided with a flow adjustable capillary tube 37 and refrigerant recovering valves 36a, 36b. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an outdoor unit and a plurality of indoor units, and enables a plurality of indoor units to perform cooling operation or heating operation at the same time, or these heating operation and cooling operation are mixed. The present invention relates to an air conditioner that can be implemented and an outdoor heat exchanger switching control method for an air conditioner.

[0002]

2. Description of the Related Art An air conditioner capable of simultaneously performing a cooling operation or a heating operation on a plurality of indoor units, or a mixture of the heating operation and the cooling operation is known.
For example, it is published in Japanese Patent No. 2804527. In such an air conditioner, an outdoor unit equipped with a compressor and an outdoor heat exchanger and an indoor unit equipped with an indoor heat exchanger are connected by inter-unit piping.

One end of the outdoor heat exchanger in the outdoor unit is selectively connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor via a four-way valve. The inter-unit pipe has a high pressure gas pipe connected to the refrigerant discharge pipe, a low pressure gas pipe connected to the refrigerant suction pipe, and a liquid pipe connected to the other end of the outdoor heat exchanger. Consists of

On the other hand, in the indoor unit, one end of the indoor heat exchanger is selectively connected to the high-pressure gas pipe and the low-pressure gas pipe of the inter-unit pipe via a valve unit, and the other end is a liquid pipe of the inter-unit pipe. It is connected to the.

In such an air conditioner, it is necessary to switch the outdoor heat exchanger of the outdoor unit from the condenser to the evaporator or from the evaporator to the condenser in response to the fluctuation of the cooling / heating load of the indoor unit. .

Of these, when the outdoor heat exchanger is switched from the condenser to the evaporator in response to the heating and cooling load of the indoor unit, the liquid refrigerant stored in the outdoor heat exchanger functioning as the condenser is stored in the accumulator. There is a risk that a large amount of liquid will flow into the compressor in excess of its capacity and liquid back will occur in the compressor.

In order to avoid this liquid back, before the outdoor heat exchanger is switched from the condenser to the evaporator, the compressor is temporarily stopped, or the compressor is not stopped, and is stored in the outdoor heat exchanger. Liquid refrigerant is flowing to the indoor unit that is in a stopped state. In this way, the outdoor heat exchanger is switched to the evaporator when a large amount of liquid refrigerant does not exist in the outdoor heat exchanger.

[0008]

However, in the prior art as described above, when switching the outdoor heat exchanger from the condenser to the evaporator, the compressor is temporarily stopped to stop the operation of the air conditioner. It is necessary to prevent the comfortable operation of the air conditioner. Further, when the liquid refrigerant flows from the outdoor heat exchanger to the indoor unit in the stopped state, annoying noise is generated in the indoor unit, and even at this time, comfortable operation of the air conditioner cannot be realized.

The object of the present invention has been made in consideration of the above circumstances, and the switching of the outdoor heat exchanger corresponding to the fluctuation of the cooling and heating load of the indoor unit is performed while maintaining the comfort of the air conditioner. An object is to provide an air conditioner that can be implemented and an outdoor heat exchanger switching control method for the air conditioner.

[0010]

The invention according to claim 1 is an outdoor unit comprising a compressor and an outdoor heat exchanger,
A plurality of indoor units equipped with an indoor heat exchanger is connected by inter-unit piping, one end of the outdoor heat exchanger,
Alternately connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, the inter-unit pipe, a high-pressure gas pipe connected to the refrigerant discharge pipe, and a low-pressure gas pipe connected to the refrigerant suction pipe , A liquid pipe connected to the other end of the outdoor heat exchange, each indoor unit, one end of the indoor heat exchanger through the valve unit to the high-pressure gas pipe and the low-pressure gas pipe And the other end is connected to the above liquid pipe,
A plurality of indoor units can be cooled or heated at the same time, or in an air conditioner configured to be able to perform a mixed cooling operation and a heating operation, one end of the outdoor heat exchanger The refrigerant suction pipe is connected by a bypass pipe whose flow rate can be adjusted.

According to a second aspect of the present invention, in the first aspect of the invention, the bypass pipe is provided with an opening / closing valve and a throttle member capable of adjusting the flow rate of the refrigerant. It is a thing.

According to a third aspect of the invention, in the first aspect of the invention, a flow rate adjusting valve capable of adjusting the flow rate of the refrigerant is disposed in the bypass pipe.

According to a fourth aspect of the present invention, an outdoor unit including a compressor and an outdoor heat exchanger and a plurality of indoor units including an indoor heat exchanger are connected by unit pipes, and the outdoor heat One end of the exchanger is alternatively connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, the inter-unit piping is connected to the high pressure gas pipe connected to the refrigerant discharge pipe, and the refrigerant suction pipe Low pressure gas pipe, and a liquid pipe connected to the other end of the outdoor heat exchange, each indoor unit, one end of the indoor heat exchanger is the high pressure gas pipe and the low pressure gas Alternative connection to the pipe through a valve unit, the other end is connected to the liquid pipe, to enable the plurality of indoor units at the same time cooling operation or heating operation,
Alternatively, in the outdoor heat exchanger switching control method of the air conditioner that enables both the cooling operation and the heating operation to be carried out in a mixed manner, the outdoor heat exchanger is condensed by the condenser in response to the fluctuation of the heating and cooling load of the indoor unit. Before switching from the to the evaporator, the liquid refrigerant stored in the outdoor heat exchanger is controlled to be returned to the refrigerant suction pipe.

In the invention described in claim 1, 2 or 3,
It has the following effects.

Since one end of the outdoor heat exchanger and the refrigerant suction pipe are connected by the bypass pipe whose flow rate can be adjusted, the outdoor heat exchanger of the outdoor unit can be operated in response to the fluctuation of the cooling and heating load of the indoor unit. Before switching from the condenser to the evaporator, the liquid refrigerant stored in the outdoor heat exchanger functioning as the condenser can be gradually returned to the refrigerant suction pipe via the bypass pipe. As a result, when switching the outdoor heat exchanger from the condenser to the evaporator, it is possible to avoid the occurrence of liquid back in the compressor, so that the operation of the compressor can be continued and the outdoor heat exchange to the indoor unit in the stopped state is possible. It is not necessary to allow the stored liquid refrigerant in the vessel to flow in. Therefore, the outdoor heat exchanger can be switched from the condenser to the evaporator while maintaining the comfort of the air conditioner.

The invention according to claim 4 has the following operation.

Before switching the outdoor heat exchanger from the condenser to the evaporator in response to the fluctuation of the cooling and heating load of the indoor unit,
Since the liquid refrigerant stored in the outdoor heat exchanger is controlled so as to be returned to the refrigerant suction pipe, by gradually returning the liquid refrigerant in the outdoor heat exchanger to the refrigerant suction pipe, the liquid bag is returned to the compressor. It can be avoided. As a result, the operation of the compressor can be continued, and the stored liquid refrigerant in the outdoor heat exchanger does not have to flow into the stopped indoor unit. Therefore, the comfort of the air conditioner can be maintained and the outdoor heat exchanger can be maintained. Can be switched from condenser to evaporator.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner according to the present invention, and is a diagram showing a case where all indoor units are in a cooling operation. This air conditioner 30
Is an outdoor unit 1 including a compressor 2, outdoor heat exchangers 3a and 3b, and outdoor expansion valves 27a and 27b, and an indoor unit 5a including an indoor heat exchanger 6a and an indoor expansion valve 18a.
And an indoor unit 5b having an indoor heat exchanger 6b and an indoor expansion valve 18b. Then, the outdoor unit 1 and the indoor units 5a, 5b are connected by the inter-unit pipe 10, and the air conditioner 30 is
The indoor units 5a and 5b can be simultaneously cooled or heated, or these cooling and heating operations can be performed in a mixed manner.

In the outdoor unit 1, the outdoor heat exchanger 3
One ends of a and 3b are selectively connected to the discharge pipe 7 and the suction pipe 8 of the compressor 2 via a four-way valve 9. The oil separator 31 is arranged in the discharge pipe 7, and the accumulator 4 is arranged in the suction pipe 8. Further, the compressor 2
This engine 32 can be driven by the engine 32.
The capacity can be changed depending on the number of rotations.

The inter-unit pipe 10 is a high pressure gas pipe 1
1, a low pressure gas pipe 12 and a liquid pipe 13 are provided. The high-pressure gas pipe 11 is connected to the discharge pipe 7, and the low-pressure gas pipe 12 is connected to the suction pipe 8. The liquid pipe 13 is connected to the other ends of the outdoor heat exchangers 3a and 3b via the receiver tank 33 and the outdoor expansion valves 27a and 27b.

The other ends of the indoor heat exchangers 6a and 6b of the indoor units 5a and 5b are a liquid branch pipe 19a having an indoor expansion valve 18a and an indoor expansion valve 18b.
Are connected to the liquid pipes 13 via the liquid branch pipes 19b.

The indoor heat exchanger 6a of the indoor unit 5a has one end connected to the high pressure gas pipe 11 via the gas branch pipe 14a and to the low pressure gas pipe 12 via the gas branch pipe 15a. Connected. Further, one end of the indoor heat exchanger 6b of the indoor unit 5b is connected to the high pressure gas pipe 11 via the gas branch pipe 14b and is connected to the low pressure gas pipe 12 via the gas branch pipe 15b. .

In each of the gas branch pipes 14a and 14b,
Discharge side valves 16a and 16b are provided. In addition, suction side valves 17a, 17b are provided in the gas branch pipes 15a, 15b, respectively.
b is provided. The branch valve unit 20a is configured by including the discharge side valve 16a and the suction side valve 17a. Similarly, the branch valve unit 20b is configured to include the discharge side valve 16b and the suction side valve 17b.

When one of the discharge side valve 16a and the suction side valve 17a is opened, the other is closed. Discharge side valve 16
Similarly, with respect to b and the suction side valve 17b, when one is opened, the other is closed. Accordingly, one end of each indoor heat exchanger 6a, 6b is connected to the high pressure gas pipe 11 of the inter-unit pipe 10 by the branch valve units 20a, 20b.
And the low-pressure gas pipe 12 are alternatively connected.

The indoor unit 5a further includes an indoor fan 23a.
Similarly, the indoor unit 5b has an indoor fan 23b.
Have. The indoor fans 23a, 23b are arranged close to the indoor heat exchangers 6a, 6b, respectively, and blow air to the respective indoor heat exchangers 6a, 6b.

Incidentally, reference numerals 34a and 34b in FIGS.
Is an open / close type discharge valve for selectively flowing the refrigerant to the outdoor heat exchangers 3a, 3b. Further, reference numeral 28 is the outdoor heat exchanger 3
It is an outdoor fan that blows air to a and 3b.

The air conditioner 30 constructed as described above
The cooling operation and the heating operation of the above will be described below.

When all the indoor units 5a and 5b are cooled at the same time, as shown in FIG. 1, the outdoor heat exchangers 3a and 3b.
The four-way valve 9 is switched so that one end of b is connected to the discharge pipe 7, and the discharge side valve 1 of the branch valve units 20a and 20b is connected.
6a, 16b are closed, and suction side valves 17a, 17
Open b. Thereby, the refrigerant discharged from the compressor 2 sequentially flows to the discharge pipe 7, the oil separator 31, the four-way valve 9, and the outdoor heat exchangers 3a and 3b, and the outdoor heat exchangers 3a and 3b functioning as a condenser. After condensing and liquefying with the outdoor expansion valves 27a and 27b and the receiver tank 33,
Further, the liquid is distributed to the indoor expansion valves 18a and 18b of the respective chamber units 5a and 5b through the liquid pipe 13 and the liquid branch pipes 19a and 19b, and the pressure is reduced there. After that, the refrigerant evaporates and vaporizes in the indoor heat exchangers 6a and 6b, and then the suction side valve 1
After flowing through 7a and 17b, the low pressure gas pipe 12, the suction pipe 8 and the accumulator 4 are sequentially passed through and sucked into the compressor 2. In this way, all the indoor units 5a, 5b are simultaneously cooled by the action of the indoor heat exchangers 6a, 6b functioning as evaporators.

On the contrary, when heating all the indoor units 5a and 5b at the same time, as shown in FIG.
The four-way valve 9 is switched so that one ends of a and 3b are connected to the suction pipe 8, the discharge side valves 16a and 16b of the branch valve units 20a and 20b are opened, and the suction side valve 17
Close a and 17b. As a result, the refrigerant discharged from the compressor 2 is distributed to the gas branch pipes 14a and 14b through the discharge pipe 7 and the high-pressure gas pipe 11 in sequence, and then the discharge side valve 16
a, 16b, an indoor heat exchanger 6a functioning as a condenser,
6b, where they are condensed and liquefied, respectively, and then merged in the liquid pipe 13 via the liquid branch pipes 19a and 19b. Then, after passing through the receiver tank 33, the outdoor expansion valves 27a, 27
Outdoor heat exchanger 3 that is decompressed in b and functions as an evaporator
After being evaporated and vaporized by a and 3b, it is sucked into the compressor 2 through the four-way valve 9, the suction pipe 8 and the accumulator 4 in this order. In this way, all the indoor units 5a, 5b are heated simultaneously by the action of each indoor heat exchanger 6a, 6b functioning as a condenser.

Further, for example, by cooling the indoor unit 5a,
When heating the indoor unit 5b, as shown in FIG. 3, the four-way valve 9 is switched so that one end of the outdoor heat exchanger 3a is connected to the suction pipe 8, and the indoor unit 5a is cooled. Discharge side valve 16a of the branch valve unit 20a
Is closed, the suction side valve 17a is opened, and the discharge side valve 16b of the branch valve unit 20b corresponding to the indoor unit 5b to be heated is opened and the suction side valve 17b is closed. Then, the refrigerant discharged from the compressor 2 is discharged into the discharge pipe 7,
After passing through the high-pressure gas pipe 11, the discharge side valve 16b of the branch valve unit 20b corresponding to the indoor unit 5b to be heated and the indoor heat exchanger 6b functioning as a condenser flow to be condensed and liquefied in the indoor heat exchanger 6b.

A part of the refrigerant condensed and liquefied in the indoor heat exchanger 6b passes through the liquid pipe 13 and the indoor unit 5a.
After being decompressed by the indoor expansion valve 18a, it is evaporated and vaporized by the indoor heat exchanger 6a which functions as an evaporator, and then flows to the suction pipe 8 through the suction side valve 17a and the low pressure gas pipe 12. The remaining refrigerant condensed and liquefied in the indoor heat exchanger 6b flows through the liquid pipe 13, is expanded by the outdoor expansion valve 27a via the receiver tank 33, and is connected to the outdoor heat exchanger 3a functioning as an evaporator and the four-way valve 9. After that, it flows into the suction pipe 8.

The indoor heat exchanger 6a and the outdoor heat exchanger 3 described above.
The refrigerant evaporated in a) is merged in the suction pipe 8 and is sequentially sucked into the compressor 2 through the accumulator 4. In this way, the indoor unit 5b is heated by the action of the indoor heat exchanger 6b that functions as a condenser, and the indoor unit 5a is cooled by the action of the other indoor heat exchanger 6a that functions as an evaporator.

As described above, the indoor unit 5a for cooling is
Indoor unit 5 that is heated by the cooling capacity (cooling load) of 5b
When it is larger than the heating capacity (heating load) of a and 5b, the outdoor heat exchangers 3a and 3b are used as condensers, and conversely, the indoor unit 5a that heats the cooling capacity (cooling load) of the indoor units 5a and 5b for cooling. When it is smaller than the heating capacity (heating load) of 5b, the outdoor heat exchangers 33a and 3b are caused to function as evaporators, so that the arbitrary indoor units 5a and 5b
b can be freely air-conditioned.

By the way, in the outdoor unit 1, one ends of the outdoor heat exchangers 3a and 3b and the suction pipe 8 are connected by a bypass pipe 35.
Further, refrigerant recovery valves 36a and 36b as opening / closing valves and a capillary tube 37 as a throttle member are arranged.

That is, the bypass branch pipe 35a provided with the refrigerant recovery valve 36a is connected to the pipe between one end of the outdoor heat exchanger 3a and the discharge pipe 34a, and the pipe between the one end of the outdoor heat exchanger 3b and the discharge pipe 34b is connected. Is connected to a bypass branch pipe 35b having a refrigerant recovery valve 36b. These bypass branch pipes 35a and 35b are merged by a bypass merge pipe 35c provided with a capillary tube 37, and this bypass merge pipe 35c is connected to the accumulator 4 in the suction pipe 8.
Connected to the upstream side of. The bypass branch pipes 35a, 3
5b and bypass merging pipe 35c to bypass pipe 35
Is configured. Further, the flow rate of the refrigerant flowing in the bypass pipe 35 can be adjusted by the capillary tube 37.

As described above, the four-way valve 9 switches the outdoor heat exchangers 3a and 3b from the condenser to the evaporator and from the evaporator to the condenser in response to the fluctuation of the cooling and heating loads of the indoor units 5a and 5b. .

Of these, when the four-way valve 9 switches the outdoor heat exchangers 3a and 3b from the condenser to the evaporator, the outdoor heat exchanger functioning as a condenser before the operation of the four-way valve 9 for this switching. The liquid refrigerant stored in 3a and 3b is controlled so as to be returned into the suction pipe 8 through the bypass pipe 35.
In this control, the stored liquid refrigerant in the outdoor heat exchangers 3a and 3b is gradually returned to the suction pipe 8 by the action of the capillary tube 37. This prevents a large amount of liquid refrigerant from flowing into the compressor 2 beyond the capacity of the accumulator 4 and prevents the occurrence of liquid back in the compressor 2.

As described above, after the liquid refrigerant stored in the outdoor heat exchangers 3a and 3b functioning as the condenser is sufficiently discharged to the suction pipe 8 side, the four-way valve 9 is operated to open the outdoor. The heat exchangers 3a and 3b are switched from the condenser to the evaporator.

With the above configuration, the following effects can be obtained according to the above embodiment.

That is, one end of each of the outdoor heat exchangers 3a and 3b and the suction pipe 8 have the flow rate adjustable capillary tube 3
7 and the refrigerant recovery valves 36a and 36b are connected by the bypass pipe 35, the indoor unit 5
The outdoor heat exchanger 3a functioning as a condenser before switching the outdoor heat exchangers 3a and 3b of the outdoor unit 1 from the condenser to the evaporator in response to the fluctuation of the heating and cooling loads of a and 5b.
And the liquid refrigerant stored in 3b can be gradually returned to the suction pipe 8 through the bypass pipe 35. As a result, when switching the outdoor heat exchangers 3a and 3b from the condenser to the evaporator, it is possible to avoid the occurrence of liquid back in the compressor 2, so that the operation of the compressor 2 can be continued and the indoors in a stopped state can be continued. The stored liquid refrigerant in the outdoor heat exchangers 3a and 3b does not flow into the units 5a and 5c. Therefore, the air conditioner 30 can be continuously operated, and no offensive noise due to the refrigerant flowing into the stopped indoor units 5a and 5b is generated, so that the outdoor heat exchanger 3a is maintained while maintaining the comfort of the air conditioner 30. And 3b can be switched from condenser to evaporator.

Although the present invention has been described based on the above embodiment, the present invention is not limited to this.

For example, in the above embodiment, the bypass pipe 35 is provided with the refrigerant recovery valves 36a and 36b as opening / closing valves.
And the capillary tube 37 with which the flow rate of the refrigerant can be adjusted have been described.
Instead of 6b and the capillary tube 37, it may have a flow rate adjusting valve capable of adjusting the flow rate of the refrigerant.

[0044]

According to the air conditioner of the present invention, it is possible to maintain the comfort of the air conditioner by switching the outdoor heat exchanger corresponding to the fluctuation of the heating and cooling load of the indoor unit. It can be done while

According to the outdoor heat exchanger switching control method of the air conditioner pertaining to the fourth aspect of the present invention, switching of the outdoor heat exchanger corresponding to fluctuations in the heating / cooling load of the indoor unit is performed comfortably in the air conditioner. It can be implemented while maintaining the sex.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner according to the present invention, and is a diagram showing a case where all indoor units are in a cooling operation.

FIG. 2 is a diagram showing a case where all the indoor units are in a heating operation in the refrigerant circuit diagram of FIG.

FIG. 3 is a diagram showing a case where one of the different indoor units is in a cooling operation and the other is in a heating operation in the refrigerant circuit diagram of FIG. 1.

[Explanation of symbols]

1 outdoor unit 2 compressor 3a, 3b outdoor heat exchanger 5a, 5b Indoor unit 6a, 6b Indoor heat exchanger 7 Discharge pipe (refrigerant discharge pipe) 8 Suction pipe (refrigerant suction pipe) 9 four-way valve Piping between 10 units 11 high-pressure gas pipe 12 Low pressure gas pipe 13 liquid tubes 20a, 20b Branch valve unit (valve unit) 30 Air conditioner 35 Bypass piping 36a, 36b Refrigerant recovery valve (open / close valve) 37 Capillary tube (throttle member)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3L092 AA03 AA10 BA05 BA28 DA19                       EA20 FA24 GA06 GA09 HA01                       HA10 JA08 KA17 LA04

Claims (4)

[Claims] 1. An outdoor unit having a compressor and an outdoor heat exchanger and a plurality of indoor units having an indoor heat exchanger are connected by unit piping, and one end of the outdoor heat exchanger is Alternately connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, the inter-unit pipe, a high pressure gas pipe connected to the refrigerant discharge pipe, a low pressure gas pipe connected to the refrigerant suction pipe, And a liquid pipe connected to the other end of the outdoor heat exchange, each of the indoor units, one end of the indoor heat exchanger through the valve unit to the high pressure gas pipe and the low pressure gas pipe Alternately connected, the other end is connected to the liquid pipe, such that the plurality of indoor units can be simultaneously cooling operation or heating operation, or these cooling operation and heating operation can be performed in combination. In the configured air conditioner An air conditioner, wherein one end of the outdoor heat exchanger and the refrigerant suction pipe are connected by a bypass pipe whose flow rate can be adjusted. 2. The air conditioner according to claim 1, wherein an opening / closing valve and a throttle member capable of adjusting the flow rate of the refrigerant are arranged in the bypass pipe. 3. The air conditioner according to claim 1, wherein the bypass pipe is provided with a flow rate adjusting valve capable of adjusting the flow rate of the refrigerant. 4. An outdoor unit including a compressor and an outdoor heat exchanger and a plurality of indoor units including an indoor heat exchanger are connected by unit piping, and one end of the outdoor heat exchanger is Alternately connected to the refrigerant discharge pipe and the refrigerant suction pipe of the compressor, the inter-unit pipe, a high pressure gas pipe connected to the refrigerant discharge pipe, a low pressure gas pipe connected to the refrigerant suction pipe, And a liquid pipe connected to the other end of the outdoor heat exchange, each of the indoor units, one end of the indoor heat exchanger through the valve unit to the high pressure gas pipe and the low pressure gas pipe Air that is connected to one of the alternatives and has the other end connected to the liquid pipe, and that enables a plurality of indoor units to perform cooling operation or heating operation at the same time, or enables these cooling operation and heating operation to coexist. Switching the outdoor heat exchanger of the air conditioner In the control method, the liquid refrigerant stored in the outdoor heat exchanger is transferred to the refrigerant suction pipe before the outdoor heat exchanger is switched from the condenser to the evaporator in response to the fluctuation of the heating / cooling load of the indoor unit. An outdoor heat exchanger switching control method for an air conditioner, characterized by controlling to return.