JP3984257B2 - Air conditioner - Google Patents

Description

  The present invention relates to a gas injection type air conditioner.

Some air conditioners include a compressor, a condenser, an evaporator, and an expansion valve, and are further provided with a gas injection circuit to improve heating capacity. The gas injection circuit is composed of a gas-liquid separator provided between the condenser and the evaporator, an injection pipe connected from the gas-liquid separator to the compressor, and an electromagnetic valve provided in the injection pipe. The gas component (gas refrigerant) is separated from the two-phase refrigerant mixed with gas and liquid, and the gas refrigerant is returned to the compressor without passing through the evaporator.
Here, during the cooling operation, the refrigerant passing through the gas-liquid separator becomes a liquid refrigerant, so that the inside of the gas-liquid separator is filled with the liquid refrigerant. As the capacity of the gas-liquid separator, a capacity of about 1 liter is widely used. For example, in an air conditioner of about 2 horsepower, the refrigerant is 2 to 3 kg (2 to 3 liters in a liquid volume). Therefore, if a large amount of liquid refrigerant stagnates in the gas-liquid separator during cooling, the amount of refrigerant is insufficient and cooling performance is degraded. Therefore, the conventional air conditioner is provided with an expansion valve between each of the gas-liquid separator, the condenser, and the evaporator to reduce the amount of refrigerant stagnating in the gas-liquid separator. (For example, refer to Patent Document 1).

Thus, an example of a conventional air conditioner in which expansion valves are provided before and after the gas-liquid separator will be specifically described with reference to FIG.
The air conditioner 101 includes an outdoor unit 102 and an indoor unit 103. The outdoor unit 102 includes a compressor 104 and an outdoor heat exchanger 105, and the indoor unit 103 includes an indoor heat exchanger 106. A gas-liquid separator 107 is connected between the heat exchangers 105 and 106 by pipes 108 and 109. Further, an injection pipe 110 extends from the gas-liquid separator 107 so that the gas refrigerant can be recovered to the compressor 104 via the accumulator 111. Here, an expansion valve 112 is provided in the middle of the pipe 108, and an expansion valve 113 is provided in the middle of the pipe 109. During cooling, the outdoor heat exchanger 105 and the indoor heat exchanger 106 function as a condenser and an evaporator, respectively.

In the air conditioner 101, during the cooling operation, the expansion valve 113 is fully opened and the expansion valve 112 is used as a throttle mechanism. The solenoid valve 114 in the middle of the injection pipe 110 is closed and no injection is performed. By making the refrigerant flowing into the gas-liquid separator 107 into a low-pressure two-phase refrigerant by the expansion valve 112, a large amount of liquid refrigerant is prevented from staying in the gas-liquid separator 107.
During heating, the expansion valve 112 is fully opened, and the expansion valve 113 is a throttle mechanism. As a result, a gas refrigerant for injection is generated in the gas-liquid separator 107, and this gas refrigerant is recovered in the compressor 104 through the injection pipe 110. When the outside air temperature is high, the solenoid valve 114 may be closed so that the injection is not performed.
JP 2002-81767 A

However, this type of air conditioner 101 has a problem of high cost because it is necessary to install the two expansion valves 112 and 113 so as to sandwich the gas-liquid separator 107 therebetween. Furthermore, during cooling operation, it is not possible to completely prevent the two-phase refrigerant with a high liquid ratio before evaporation from accumulating in the gas-liquid separator, so the amount of refrigerant circulating in the refrigeration cycle is reduced and the capacity is reduced. There was a problem to do.
This invention is made | formed in view of such a situation, The place made into the objective is to reduce apparatus cost in an air conditioner provided with a gas injection circuit. Moreover, in an air conditioner provided with a gas injection circuit, it is to prevent liquid refrigerant from accumulating in the gas-liquid separator during cooling operation.

  The invention according to claim 1 of the present invention for solving the above-mentioned problems is the circulation of the refrigerant pressurized by the compressor to the indoor heat exchanger and the outdoor heat exchanger, and the indoor heat exchanger, the outdoor heat exchanger, In the air conditioner configured to be able to recover the gas refrigerant from the gas-liquid separator disposed between the two through the injection pipe to the compressor, a first connecting the outdoor heat exchanger and the gas-liquid separator. And a second rectifier that prevents the flow of refrigerant from the outdoor heat exchanger toward the gas-liquid separator, and a second that connects the indoor heat exchanger and the gas-liquid separator. A second rectifying unit provided in the pipe for controlling the flow of the refrigerant from the indoor heat exchanger toward the gas-liquid separator, and the refrigerant discharged from the outdoor heat exchanger, the gas-liquid separator Bypass piping to supply the indoor heat exchanger without passing through, And a bypass circuit having a third rectifying unit for preventing the refrigerant from flowing from the indoor heat exchanger to the outdoor heat exchanger provided in the bypass pipe. It was.

  In this air conditioner, during heating operation, the refrigerant discharged from the indoor heat exchanger flows into the gas-liquid separator and is then supplied to the outdoor heat exchanger. At this time, the refrigerant does not flow through the bypass circuit due to the presence of the third rectifying unit. Moreover, when using injection piping, the gas refrigerant stagnated in a gas-liquid separator is made to collect | recover by a compressor not via an outdoor heat exchanger. During the cooling operation, the first rectification unit and the second rectification unit do not allow the refrigerant to flow into the gas-liquid separator, but are supplied to the indoor heat exchanger through the bypass circuit.

The invention according to claim 2 is the air conditioner according to claim 1, wherein the first rectification unit and the third rectification unit are check valves.
In this air conditioner, the flow of the refrigerant is regulated using a check valve. By using the check valve, switching control of the expansion valve or the like is not necessary.

According to a third aspect of the present invention, in the air conditioner according to the first or second aspect, the bypass circuit includes the second pipe between the indoor heat exchanger and the second rectifying unit. The throttle part which adjusts the pressure of a refrigerant is provided in the 2nd piping between this connection part and the indoor heat exchanger.
In this air conditioner, one throttle is provided on a path common to both the cooling operation and the heating operation, and the pressure of the refrigerant between the heat exchangers is adjusted by this throttle.

The invention according to claim 4 is the air conditioner according to claim 3, wherein the throttle portion is a capillary.
In this air conditioner, the throttle portion is formed of a capillary, and the refrigerant is decompressed substantially uniformly by the capillary.

According to a fifth aspect of the present invention, in the air conditioner according to any one of the first to fourth aspects, the controller that opens the electromagnetic valve provided in the injection pipe during cooling operation is provided. It is characterized by providing.
In this air conditioner, during the cooling operation, no new refrigerant flows into the gas-liquid separator. However, if the refrigerant has accumulated in the gas-liquid separator in advance, this refrigerant is used as the gas refrigerant. It is discharged from the injection pipe.

  According to the present invention, the bypass circuit is provided so that the refrigerant does not flow into the gas-liquid separator when the refrigerant is circulated from the outdoor heat exchanger to the indoor heat exchanger during the cooling operation. The number of required expansion valves can be reduced. Therefore, it is possible to reduce the number of expensive parts used and to reduce the processing load on the control unit, thereby reducing the cost of the air conditioner. In addition, since the refrigerant does not flow into the gas-liquid separator during the cooling operation, the refrigerant is not lost in the gas-liquid separator, and a sufficient cooling capacity can be realized.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
(First embodiment)
FIG. 1 is a circuit diagram showing a configuration of an air conditioner according to the present embodiment.
As shown in FIG. 1, the air conditioner 1 includes an outdoor unit 2 and an indoor unit 3.
The outdoor unit 2 includes a compressor 4 that pressurizes the refrigerant, and a discharge port of the compressor 4 is connected to a first port 6 a of the four-way valve 6 by a pipe 5. A pipe 7 is connected to the second port 6 b of the four-way valve 6, and this pipe 7 is connected to the outdoor heat exchanger 8. An indoor heat exchanger 10 of the indoor unit 3 is connected to the third port 6 c of the four-way valve 6 via a pipe 9. An accumulator 12 is connected to the fourth port 6 d of the four-way valve 6 via a pipe 11 so that the refrigerant can be recirculated to the compressor 4 via the accumulator 12.

  A gas-liquid separator 16 is connected to the outdoor heat exchanger 8 via a pipe (first pipe) 15. A check valve 17 is provided in the pipe 15. The check valve 17 allows the refrigerant to flow in the direction from the gas-liquid separator 16 to the outdoor heat exchanger 8, but does not allow the refrigerant to flow in the direction from the outdoor heat exchanger 8 to the gas-liquid separator 16. It is the 1st rectification | straightening part set so that a flow might be prohibited.

An injection pipe 18 is connected to the gas-liquid separator 16. The injection pipe 18 is a pipe that is partially a capillary 18 a and is connected to the input pipe 11 of the accumulator 12. Further, an electromagnetic valve 19 is provided in the injection pipe 18. The gas-liquid separator 16, the injection pipe 18 and the electromagnetic valve 19 constitute a gas injection circuit 20.
Further, the gas-liquid separator 16 is connected to the indoor heat exchanger 10 by a pipe (second pipe) 21. In the pipe 21, an electromagnetic valve 22 that is a second rectification unit and an expansion valve 23 that is a throttle unit are arranged in order from the gas-liquid separator 16 side.

  Here, the outdoor unit 2 is provided with a bypass circuit 25 so as to directly connect the pipe 15 and the pipe 21. The bypass circuit 25 includes a bypass pipe 26 and a check valve 27 provided in the bypass pipe 26. One end portion of the bypass pipe 26 is connected to a connection portion 28 formed between the outdoor heat exchanger 8 of the pipe 15 and the check valve 17. The other end of the bypass pipe 26 is connected to a connection part 29 formed between the solenoid valve 22 and the expansion valve 23 of the pipe 21. The check valve 27 is a third valve set to allow the refrigerant to flow in the direction from the outdoor heat exchanger 8 to the indoor heat exchanger 10 and prohibit the refrigerant from flowing in the opposite direction. The rectifying unit.

  The outdoor unit 2 is provided with a control unit 30. The control unit 30 searches the map stored in advance according to the room temperature or the user's operation, and controls the four-way valve 6, the electromagnetic valve 19, the electromagnetic valve 22, and the expansion valve 23. It is configured.

Next, the operation of the air conditioner 1 will be described.
First, Table 1 shows operations of the solenoid valve 19, the solenoid valve 22, and the expansion valve 23 controlled by the control unit 30.

  As shown in Table 1, at the time of heating operation, it is possible to select two modes, a normal operation without gas injection and an operation at a low outside temperature in which gas injection is performed. As shown in Table 1, during normal operation, the solenoid valve 19 is closed and the solenoid valve 22 is opened. The opening degree of the expansion valve 23 is adjusted according to normal control, that is, a set temperature or the like. The four-way valve 6 is switched so that the first port 6a and the third port 6c communicate with each other, and the second port 6b and the fourth port 6d communicate with each other. Thereby, as shown in FIG. 2, the refrigerant flows in the direction indicated by the arrow A1. That is, the high-pressure gas refrigerant discharged from the compressor 4 passes through the pipe 9 and is led to the indoor heat exchanger 10 of the indoor unit 3 where the heat is released and liquefied, and the pipe 21 serves as a high-pressure liquid refrigerant. Discharged from. This liquid refrigerant is reduced in pressure by the expansion valve 23 to become a two-phase flow refrigerant mixed with gas and liquid, and then flows into the gas-liquid separator 16 through the electromagnetic valve 22. At this time, since the check valve 27 does not allow the liquid refrigerant to flow in this direction, the liquid refrigerant does not flow into the outdoor heat exchanger 8 through the bypass pipe 26. Since the liquid refrigerant flows out from the gas-liquid separator 16 only into the pipe 15, the liquid refrigerant passes through the check valve 17 and is then guided to the outdoor heat exchanger 8. In the outdoor heat exchanger 8, the liquid refrigerant absorbs heat by heat exchange and becomes a gas refrigerant. The gas refrigerant is supplied to the accumulator 12 through the pipe 7, the four-way valve 6, and the pipe 11, and then returns to the compressor 4.

  In operation at a low outside temperature, as shown in Table 1, the solenoid valve 19 is opened, and the refrigerant flows in the gas injection circuit 20 as indicated by the arrow A2 in addition to the direction indicated by the arrow A1. . That is, the gas component contained in the refrigerant flowing into the gas-liquid separator 16 is sucked into the pipe 18, decompressed by the capillary 18 a, merged with the gas refrigerant flowing through the pipe 11, and supplied to the accumulator 12. .

  Further, as shown in Table 1, during the cooling operation, the electromagnetic valve 19 is opened, the electromagnetic valve 22 is closed, and the expansion valve 23 is switched to normal control. Furthermore, as shown in FIG. 1, the four-way valve 6 is switched. Thus, the refrigerant flows in the direction indicated by the arrow B in FIG. That is, the high-pressure gas refrigerant discharged from the compressor 4 is guided to the outdoor heat exchanger 8 through the pipe 7. In the outdoor heat exchanger 8, the refrigerant is liquefied by heat exchange. The liquid refrigerant flows into the pipe 15, but the check valve 17 does not allow the liquid refrigerant to flow in this direction, so that the liquid refrigerant flows into the bypass circuit 25. Since the check valve 27 of the bypass circuit 25 allows the flow of the liquid refrigerant in this direction, the liquid refrigerant flows directly into the pipe 21 through the bypass circuit 25. Here, since the solenoid valve 22 is closed, the liquid refrigerant does not flow into the gas-liquid separator 16 but is decompressed by the expansion valve 23 and then supplied to the indoor heat exchanger 10 of the indoor unit 3. Here, it is vaporized by an endothermic reaction by heat exchange and becomes a gas refrigerant. The gas refrigerant is discharged from the pipe 9, is introduced into the accumulator 12 through the four-way valve 6 and the pipe 11, and then returns to the compressor 4.

  As described above, during the cooling operation, the liquid refrigerant does not flow into the gas-liquid separator 16, but the liquid refrigerant may remain in the gas-liquid separator 16 as an initial state. . In this air conditioner 1, by opening the electromagnetic valve 19, the refrigerant accumulated in the gas-liquid separator 16 is taken out as a gas refrigerant and returned from the pipe 18 to the pipe 11. As a result, the refrigerant does not stay in the gas-liquid separator 16 during the cooling operation.

In this embodiment, when the gas injection circuit 20 including the gas-liquid separator 16 is provided, the bypass circuit 25 is provided and the check valve 17 is provided in the pipe 15, so that during the cooling operation, the outdoor heat exchanger 8 The liquid refrigerant can be supplied to the indoor heat exchanger 10 without using the liquid separator 16. Therefore, during the cooling operation, the refrigerant circulates without going through the gas-liquid separator 16, and the refrigerant does not flow into the gas-liquid separator 16. Therefore, the refrigerant can be effectively used and the cooling capacity is reduced. There is no. Here, since the check circuit 27 is provided in the bypass circuit 25, the refrigerant does not flow through the bypass circuit 25 during heating, and a circulation circuit similar to the conventional circuit can be formed.
Since the check valve 17 and the check valve 27 are used as means for controlling the refrigerant circulation path, the cost of parts can be reduced and the control by the control unit 30 is not required. Can be lowered. In particular, since it is not necessary to provide two expansion valves before and after the gas-liquid separator 16 as in the prior art, the air conditioner 1 is reduced in cost.
Furthermore, since the electromagnetic valve 19 of the gas injection circuit 20 is opened during the cooling operation, even when there is a liquid refrigerant stagnating in the gas-liquid separator 16, it can be discharged to the compressor 4. The refrigerant can be used effectively. Therefore, the cooling capacity is not reduced.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the same component as 1st Embodiment. In addition, overlapping explanation is omitted.
The air conditioner 31 includes an outdoor unit 32 and an indoor unit 33. A pipe (second pipe) 34 extending from the gas-liquid separator 16 is connected to the indoor heat exchanger 10 via a capillary 35 that is a constricted portion provided in the indoor unit 33. The piping 34 is provided with an expansion valve 36 and a connection portion 29 in order from the gas-liquid separator 16 side. The control unit 30 is configured to control the four-way valve 6, the electromagnetic valve 19, and the expansion valve 36.

The operation of the air conditioner 31 will be described.
In this air conditioner 31, it is possible to selectively carry out three types of operations: a normal heating operation that does not use the gas injection circuit, a heating operation at a low outside temperature that uses the gas injection circuit, and a cooling operation. it can. Table 2 shows the operation of the valves 19 and 36 for these cases.

First, during the heating operation, the four-way valve 6 is switched so that the compressor 4 and the indoor heat exchanger 10 are directly connected. Further, as shown in Table 2, during normal operation, the electromagnetic valve 19 is closed and the opening degree of the expansion valve 36 is controlled. The pressure of the high-pressure liquid refrigerant discharged from the indoor heat exchanger 10 is successively reduced by the expansion valve 36 after being reduced by the capillary 35. From the gas-liquid separator 16, the liquid refrigerant flows out only to the pipe 15, is vaporized through the outdoor heat exchanger 8, and is then collected by the compressor 4. During this time, the refrigerant does not flow through the bypass circuit 25.
The operation at the low outside air temperature is the same as that in the normal operation except that the refrigerant circulation using the gas injection circuit 20 is added.

  During the cooling operation, the four-way valve 6 is switched to the position shown in FIG. Further, as shown in Table 2, the electromagnetic valve 19 is opened and the expansion valve 36 is closed. The liquid refrigerant flows from the outdoor heat exchanger 8 through the bypass circuit 25 and flows into the pipe 34, is decompressed by the capillary 35, and then flows into the indoor heat exchanger 10. Here, the expansion valve 36 functions as a second rectification unit that prohibits liquid refrigerant from flowing in the direction from the connection unit 29 toward the gas-liquid separator 16 by maintaining the closed state. Therefore, the liquid refrigerant does not flow into the gas-liquid separator 16. Further, the liquid refrigerant stagnated in the gas-liquid separator 16 at the start of operation is recovered by the compressor 4 through the injection pipe 18.

  In this embodiment, the same effect as in the first embodiment can be obtained. Furthermore, the expansion valve 36 provided between the gas-liquid separator 16 and the indoor heat exchanger 10 performs pressure reduction during heating operation and rectifies liquid refrigerant during cooling operation. The number of valves controlled by the unit 30 can be reduced, and the cost can be further reduced.

The present invention can be widely applied without being limited to the above-described embodiments.
For example, the check valves 17 and 27 can be electromagnetic valves. Since the solenoid valve only needs to be turned ON / OFF, the control is easier and the cost can be reduced as compared with the conventional case having two expansion valves.
In the air conditioner 31 shown in FIG. 3, if only the capillary 35 on the indoor unit 33 side has insufficient pressure reduction of the liquid refrigerant during cooling, a capillary as a throttle part is added to the bypass circuit 25. In addition, the pressure may be reduced to an appropriate pressure by carrying out two-stage throttling. In this case, if a capillary is provided between the check valve 27 and the connection portion 29, the operation of the check valve 27 can be stabilized.

It is a circuit diagram which shows the structure of the air conditioner in embodiment of this invention. It is a figure explaining the circulation path of the refrigerant | coolant at the time of heating. It is a circuit diagram which shows the structure of an air conditioner. It is a circuit diagram which shows the structure of the conventional air conditioner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air conditioner, 4 ... Compressor, 8 ... Outdoor heat exchanger, 10 ... Indoor heat exchanger, 16 ... Gas-liquid separator, 18 ... Injection piping, 15 ... Pipe (first pipe), 17 ... Check valve (first rectifier), 21 ... Pipe (second pipe), 22 ... Solenoid valve (second rectifier) ), 25... Bypass circuit, 26... Bypass piping, 27... Check valve (third rectifier), 23. ... Control part 34 ... Pipe (second pipe) 35 ... Capillary (throttle part) 36 ... Expansion valve (second rectification part)

Claims (4)

The refrigerant pressurized by the compressor is circulated through the indoor heat exchanger and the outdoor heat exchanger, and the gas refrigerant is injected from the gas-liquid separator disposed between the indoor heat exchanger and the outdoor heat exchanger. In the air conditioner configured to be recoverable to the compressor through,
A first rectifier that is provided in a first pipe that connects the outdoor heat exchanger and the gas-liquid separator, and that prevents a refrigerant from flowing from the outdoor heat exchanger toward the gas-liquid separator;
A second rectification unit that is provided in a second pipe that connects the indoor heat exchanger and the gas-liquid separator, and that controls the flow of refrigerant from the indoor heat exchanger toward the gas-liquid separator;
A bypass pipe that supplies the refrigerant discharged from the outdoor heat exchanger to the indoor heat exchanger without passing through the gas-liquid separator, and the outdoor heat from the indoor heat exchanger provided in the bypass pipe A bypass circuit having a third rectification unit for preventing the flow of the refrigerant toward the exchanger ;
An air conditioner, comprising: a control unit that closes the second rectifying unit and opens an electromagnetic valve provided in the injection pipe during a cooling operation . The air conditioner according to claim 1, wherein the first rectification unit and the third rectification unit are check valves. The bypass circuit is connected to the second pipe between the indoor heat exchanger and the second rectifying unit, and between the connecting unit and the indoor heat exchanger, The air conditioner according to claim 1 or 2, wherein a throttle part for adjusting the pressure of the refrigerant is provided in the second pipe. The air conditioner according to claim 3, wherein the throttle portion is a capillary.

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