JPH0755280A - Air conditioning system - Google Patents

Abstract

PURPOSE:To prevent occurrence of lack of gas in a system by effectively displacing refrigerant stayed in an outdoor heat exchanger, i.e., refrigerant stored in the exchanger which is not used. CONSTITUTION:An air conditioning system has a plurality of outdoor heat exchangers 3a, 3b connected in parallel with a compressor 2, and comprises means 10a, 10b for communicating with a suction tube of the compressor 1 at the time of a pump-down operation with valves 9a, 9b to be closed at the time of a pump-down operation in the exchangers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an air conditioning system having a plurality of outdoor heat exchangers connected in parallel with a compressor.

[0002]

2. Description of the Related Art An air-conditioning system equipped with a computer room air conditioner and a living room air conditioner has an outside air temperature of 0.
Even if the temperature falls below ° C, the cooling operation of this computer room is required. That is, the air conditioning system is required to perform a mixed cooling / heating operation. For example, there is a case where two rooms are cooled and one room is heated, or a case where a central part of a room in which a computer (OA device) is installed is cooled and a peripheral part of the room is heated.

In the conventional air-conditioning system shown in FIG. 7, when the outside air temperature is -5.degree. C. or less and the cooling / heating mixed operation mainly of cooling is performed, the valve 101 of the outdoor heat exchanger 100 is opened to open the valve 102.
And the outdoor heat exchanger 100 becomes a condenser. At this time, the valve 104 and the valve 10 of the unused outdoor heat exchanger 103
5, and the mechanical valve 106 is closed, and the outdoor heat exchanger 10
Refrigerant is prevented from entering the inside of No. 3.

[0004]

However, these valves 1
Even if 04 and the valve 105 are closed, there is always a leak of the refrigerant in the valve 104 and the valve 105, the refrigerant leaks, and the outdoor heat exchanger 103
It gets inside. For this reason, when the air conditioning system is subjected to a cooling / heating mixed operation mainly for cooling for a long time, the refrigerant falls asleep or remains in the unused heat exchanger 103, and the entire air conditioning system is out of gas.

As described above, when the entire air-conditioning system is out of refrigerant gas, conventionally, the valve 104 and the mechanical valve 106 are opened to stop the outdoor fan 107, so that the gas discharged from the compressor is not released. Put in the used heat exchanger 103,
The lying refrigerant was expelled to the liquid pipe 108 side.

However, since the outdoor fan 107 is stopped, the outdoor fan 107 cannot cool it and the pressure of the gas discharged from the compressor may rise excessively. On the contrary, when strong wind such as building wind hits the heat exchanger 103,
The overheated exhaled gas may condense, and rather the entire air conditioning system may run out of gas.

The present invention has been made to solve the above-mentioned problems, and reliably removes the refrigerant lying in the outdoor heat exchanger, that is, the refrigerant remaining in the outdoor heat exchanger which is not in use, and air conditioning. It is an object of the present invention to provide an air conditioning system capable of preventing gas shortage in the system.

[0008]

Therefore, the present invention is an air conditioning system provided with a plurality of outdoor heat exchangers connected in parallel to a compressor, and these outdoor heat exchangers are provided with valves that are closed during pump down operation. And means for communicating with the suction pipe of the compressor during the pump down operation.

[0009]

The refrigerant remaining in the outdoor heat exchanger is expelled to the outside of the outdoor heat exchanger through the suction pipe suction path of the compressor to recover the refrigerant.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a preferred embodiment of the air conditioning system of the present invention.

The outdoor unit 1 has a compressor 2, outdoor heat exchangers 3a and 3b, and a gas-liquid separator 4. On the other hand, the plurality of indoor units 5a, 5b, 5c have indoor heat exchangers 6a, 6b, 6c, respectively.

The two outdoor heat exchangers 3a and 3b are provided with a switching valve 9 for the refrigerant discharge pipe 7 and the refrigerant suction pipe 8 of the compressor 2.
It is branched and connected via a, 9b and 10a, 10b.

On the other hand, the inter-unit pipe 11 is composed of a high pressure gas pipe 12, a low pressure gas pipe 13 and a liquid pipe 14. The inter-unit pipe 11 connects the outdoor unit 1 and the indoor units 5a, 5b, 5c.

The high pressure gas pipe 12 is branched from the refrigerant discharge pipe 7, and the low pressure gas pipe 13 is connected to the refrigerant suction pipe 8.
It has been branched from. The high-pressure gas pipe 12 is connected to the indoor heat exchangers 6a, 6b, 6c of the indoor units 5a, 5b, 5c via switching valves 15a, 15b, 15c. The low pressure gas pipe 13 includes the indoor units 5a, 5b,
It is connected to the indoor heat exchangers 6a, 6b, 6c of 5c via switching valves 16a, 16b, 16c.

Further, the liquid pipe 14 is connected to the outdoor heat exchanger 3a,
Auxiliary refrigerant decompressor 18a, 18b such as an electric expansion valve 3b
And refrigerant decompressors 17a, 17b, 17c such as electric expansion valves of the indoor heat exchangers 6a, 6b, 6c.

FIG. 2 shows each switching valve 9a, 9b, 10a, 10b during the refrigerant recovery control, the cooling operation, and the heating operation.
And the open / close states of the pressure reducing valves 17a and 17b.

With reference to FIG. 2, the cooling / heating mixing operation mainly for cooling will be described.

As an example, the indoor units 5a and 5b are cooled and the indoor unit 5c is heated. Moreover,
The outdoor heat exchanger 3a is used, but the outdoor heat exchanger 3b is not used and is stopped.

Since it is during cooling, on the outdoor unit 1 side, the outdoor heat exchanger 3a acts as a condenser. As shown in FIG. 2, since the outdoor heat exchanger 3a is used, the switching valve 9a of the outdoor heat exchanger 3b is opened and the switching valve 10a is closed. On the other hand, since the outdoor heat exchanger 3b is not used, the switching valve 9b of the outdoor heat exchanger 3b is closed and the switching valve 10b is also closed. The pressure reducing valves 17a and 17b control the degree of opening and closing. In this case, the switching valve 9a functions as a refrigerant discharge valve, and the switching valve 10a functions as a suction valve. Further, the mechanical valve 18b is closed and the opening / closing degree of the mechanical valve 18a is controlled.

On the other hand, the indoor unit 5 for cooling
a, 5b, the switching valves 16a, 16b are opened, and the switching valve 1
Close 5a and 15b. In the indoor unit 5c for heating, the switching valve 16c is closed and the switching valve 15c is opened.

A part of the high-pressure refrigerant discharged from the compressor 2 passes through the discharge pipe 7, the high-pressure gas pipe 12 and the switching valve 9a,
It flows only to one of the outdoor heat exchangers 3a. The remaining high-pressure refrigerant discharged from the compressor 2 flows through the high-pressure gas pipe 12 and the switching valve 15c of the indoor unit 5c for heating and the indoor heat exchanger 6c. Therefore, the refrigerant is condensed and liquefied in the outdoor heat exchanger 3a and the indoor heat exchanger 6c.

The condensed and liquefied refrigerant is decompressed by the refrigerant decompressors 17a and 17b through the liquid pipe 14, and then evaporated and vaporized by the indoor heat exchangers 6a and 6b.

The evaporated and vaporized refrigerant joins the low-pressure gas pipe 13 through the switching valves 16a and 16b, and is sucked into the compressor 2 through the suction pipe 8 and the gas-liquid separator 4.

In this way, the indoor heat exchanger 6c performs the heating operation, and the indoor heat exchangers 6a and 6b perform the cooling operation,
Performs cooling and heating mixed operation mainly for cooling.

However, during the air-conditioning mixed operation mainly for cooling, the outdoor heat exchanger 3 is stopped.
Although the changeover valves 9b and 10b of b are closed, the refrigerant leaks and stays (stays) in the outdoor heat exchanger 3b.

As described above, when the refrigerant remains in the outdoor heat exchanger 3b, the amount of the refrigerant in the air conditioning system shown in FIG. 1 decreases and the gas is out of gas.

Therefore, in order to eliminate the gas shortage condition in the air conditioning system, the refrigerant in the outdoor heat exchanger 3b is recovered from the outdoor heat exchanger 3b as described below.

This refrigerant recovery control operation is performed as shown in FIG. That is, the switching valves 9a and 9b are closed, the switching valves 10a and 10b are opened, and the switching valves 18a and 18b
Close b. Further, the pressure reducing valves 17a and 17b of the indoor unit that is performing the cooling operation are fully closed.

When the compressor 2 is operated in this state, the low-pressure gas pipe 13 on the suction side of the compressor 2 has a negative pressure, so that the refrigerant inside the outdoor heat exchanger 3b exchanges heat through the switching valves 10a and 10b. It is recovered from the container 3b to the compressor 2 side. As a result, it is possible to reliably eliminate the gas shortage of the refrigerant in the air conditioning system.

Here, an example of a gas shortage determination method will be described with reference to the gas shortage determination flow in FIG.

In FIG. 3, when the indoor refrigerant mode is selected by the remote controller or the like (step A), the indoor unit pressure reducing valve (mechanical valve) is operated while the vehicle is in operation and the outside air temperature is being measured in the thermo-on state (step B). Also called a valve) 17
When the number of drive pulses for a and 17b is equal to or greater than the number of pulses shown in FIG. 4 (step C), the temperature difference between the indoor heat exchanger inlet and outlet (for example, the temperature E3 (outlet) of the indoor heat exchanger 6c and the indoor heat exchanger) If the temperature E1 of 6a (inlet) is 5 ° C. or higher (step D), and the temperature difference continues for 3 minutes,
The microcomputer of the control device (not shown) determines that the refrigerant in the air conditioning system is out of gas.

When the microcomputer of the control device (not shown) judges that there is a gas shortage, it sends a signal of a gas shortage to the microcomputer for controlling the outdoor heat exchanger 3b to control the refrigerant recovery. It has become.

When the microcomputer of the control device performs the refrigerant recovery control and the refrigerant recovery is completed and the normal operation is resumed, the mechanical valve pulse of the indoor heat exchanger is reset, and the initial pulse (about 100 less than the value of FIG. 4). Value), the gas shortage signal is not sent again from the indoor heat exchanger immediately after the refrigerant is recovered.

As described above, in this embodiment, the refrigerant remaining in the outdoor heat exchanger 3b, which is inactive by closing the switch 9b and opening the switch 10b, is completely recovered in the air conditioning system. be able to.

In other words, the refrigerant remaining in the open outdoor heat exchanger 3b is put into a so-called pump-down state to recover the refrigerant. During the control of recovering the refrigerant in the pump down state, the outdoor fan is operated.

The time for this pump down is the compressor 2
(Frequency), the thermistor temperature of the outdoor heat exchanger 3b, the pressure sensor (switch), the outside air temperature and other parameters are made variable so that the protection function of the compressor 2 does not work.

It is preferable that the recovery of the refrigerant is carried out not only when the air-conditioning system runs out of gas, but also periodically when the air-conditioning system is started and during operation.

Further, the pressure reducing valves 18a, 18b of the cooling indoor unit 17a, 17b may not only be fully closed as described above, but may be narrowed down considerably, for example. In either case, the compressor is operated to bring the low pressure below the saturation pressure for the outside air.

Next, another preferred embodiment of the air conditioning system of the present invention will be described.

The air conditioning system shown in FIG. 5 has an outdoor unit 110, indoor units 160 and 162, and a control unit 2.
Has 0.

The outdoor unit 110 includes the outdoor heat exchanger 11
4, 116, and a fossil fuel type boiler unit 118 for heating the refrigerant.

The outdoor heat exchangers 114 and 116 are the four-way valve 1
It is connected to 22. The four-way valve 122 is turned on during heating and turned off during cooling. The four-way valve 122 is connected to the compressor 126 via a check valve 124, and the four-way valve 122 is a check valve 128.
It is connected to the compressor 130 via.

An oil supply section 132 is provided in each of the compressors 126 and 130. These compressors 12
6, 130 are both connected to the accumulator 134. The accumulator 134 is connected to the boiler unit 118 as a heat source for the refrigerant.

This boiler unit 118 has a mechanical valve M
The receiver tank 140 and the mechanical valve MV1, via V3.
It is connected to MV2. These mechanical valves MV1 and MV
2 is connected to the other ends of the heat exchangers 114 and 116, respectively.

On the other hand, the four-way valve 122 has a line 192.
Through the accumulator 134 and the boiler unit 1
18 and also to the service valve 150 via line 190. The receiver tank 140 is also connected to another service valve 152.

Next, the indoor units 160 and 162 will be described.

The indoor unit 160 has an indoor heat exchanger 164 and a mechanical valve MV4. The indoor unit 162 has an indoor heat exchanger 168 and a mechanical valve MV5. One end side and the other end side of the indoor units 160 and 162 are connected to the service valves 150 and 152, respectively.

With reference to FIGS. 5 and 6, the cooling / heating mixing operation mainly for cooling in this embodiment will be described.

FIG. 6 shows that during cooling operation, during heating of the air heat source,
The open / closed states of the mechanical valves MV1 to MV5, the four-way valve, and the two-way valve during heating of the boiler heat source and during refrigerant recovery control are shown.

Air heat source (outdoor heat exchangers 114, 116)
During heating by, the refrigerant moves in the direction of the arrow X, controls the opening / closing of the mechanical valves MV1, MV2, MV4, MV5, opens the two-way valves 114b, 116b, and opens the mechanical valve MV3.
Fully close. The four-way valve 22 is on.

When the air heat source is frosted and heated by the boiler heat source (boiler unit 118), the mechanical valve MV is used.
1, MV2 is fully closed to control opening / closing of mechanical valves MV4 and MV5, and two-way valves 114b and 116b are closed.
It controls the opening and closing of the mechanical valve MV3. The four-way valve 22 is on.

When cooling, the refrigerant moves in the direction opposite to the arrow X to fully open the mechanical valves MV1 and MV2,
Controls the opening and closing of V4 and MV5, and also the two-way valve 114
b, 116b are opened and the mechanical valve MV3 is fully closed. The four-way valve 122 is off.

When the boiler unit 118 is used for heating, if the two-way valves 114b and 116b are closed and the operation of the outdoor heat exchangers 114 and 116 is stopped, a part of the refrigerant leaks from the two-way valves 114b and 116b. Lever outdoor heat exchanger 11
4, 116, and the refrigerant is out of gas in the air conditioning system of FIG.

In this case, as shown in FIG. 6, the four-way valve 122 remains in the ON state (heating state). And
When the compressor 134 of FIG. 5 is operated, the mechanical valves MV1 to M
V5 is closed, and the line 192 side, which is the suction side of the compressor 134, has a negative pressure. As a result, the refrigerant accumulated in the outdoor heat exchangers 114 and 116 is transferred to the outdoor heat exchangers 11 and 11.
It is sucked from 4,116 to the compressor 134 side and collected, and the lack of gas in the refrigerant in the air conditioning system is eliminated.

As described above, in this embodiment, the mechanical valves MV1 and MV2 are closed to close the line 190 which is the discharge system passage of the compressor 134, thereby making the line 192 which is the suction system passage a negative pressure. , A line 19 which is a suction system passage which is made negative pressure by opening the two-way valves 114b and 116b.
By connecting the outdoor heat exchangers 114 and 116 which are at rest with respect to 2 to communicate with each other, the outdoor heat exchanger 114b which is at rest,
The refrigerant remaining in 116b can be reliably recovered.

In short, in this embodiment, the pressure accumulated on the low pressure side of the outdoor heat exchanger is reduced to recover the refrigerant accumulated in the outdoor heat exchanger which is not in use, so that the outdoor air temperature is surely low. The refrigerant can be recovered. Also,
It is not affected by the building wind as in the past.

Further, it is possible to cope with the recovery of the refrigerant laid in the suction pipe having the three water-cooled system paths shown in FIG. Further, the present invention can be variously modified, such as being applicable to a refrigerant heat pump.

[0059]

As described above, according to the present invention, the refrigerant lying in the outdoor heat exchanger, that is, the refrigerant remaining in the outdoor heat exchanger which is not in use, can be reliably recovered and used in the system. It is possible to prevent out of gas.
As a result, the air conditioning system can be recovered even when the cooling / heating mixed operation is performed.

[Brief description of drawings]

FIG. 1 is a diagram of a refrigerant circuit showing a preferred embodiment of the air conditioning system of the present invention.

FIG. 2 is a diagram showing each operating state in the embodiment of FIG.

FIG. 3 is a flowchart showing an example of gas shortage determination in FIG.

FIG. 4 is a diagram showing an example of a gas shortage determination pulse.

FIG. 5 is a diagram of a refrigerant circuit showing another preferred embodiment of the air conditioning system of the present invention.

FIG. 6 is a diagram showing each operating state in the embodiment of FIG.

FIG. 7 is a diagram for explaining refrigerant stagnation in a conventional air conditioning system.

[Explanation of symbols]

 1 outdoor unit 2 compressors 3a, 3b outdoor heat exchangers 6a, 6b, 6c indoor heat exchangers 9a, 9b, switching valves 10a, 10b switching valve 12 high-pressure gas pipe (discharging system passage) 13 low-pressure gas pipe (suction system passage) )

Claims (1)

[Claims] 1. An air conditioning system comprising a plurality of outdoor heat exchangers connected in parallel to a compressor, wherein these outdoor heat exchangers have a valve that is closed during pump down operation and a compressor that closes during the pump down operation. An air conditioning system comprising: a means for communicating with a suction pipe.