JPH04324067A - Air conditioner - Google Patents

Abstract

PURPOSE:To reduce refrigerant charging amount by reducing a diameter of a refrigerant tube in a branch type air conditioner. CONSTITUTION:A liquid tube between a heat source side heat exchanger 2 of a main refrigerant circuit 10 and an outdoor pressure reducing mechanism 4, particularly a branch liquid tube 31a of the liquid tube side of the exchanger 3 is bypass-connected to a suction line by a bypass passage 11 for cooling refrigerant through a pressure reducing mechanism. A heat exchanger 12 for heat exchanging refrigerant flowing in a downstream side tube of the mechanism 13 of the passage 11 with refrigerant flowing between an indoor pressure reducing mechanism 6 of a main refrigerant circuit 10 and the mechanism 4, is provided to cool the refrigerant in the liquid tube. Thus, refrigerant charging amount is reduced by reducing a diameter of the refrigerant tube while improving a refrigerating capacity and maintaining overheat operation preventive effect.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner equipped with outdoor and indoor pressure reducing mechanisms, and more particularly to measures for making refrigerant piping thinner.

0002

[Prior Art] Conventionally, for example, Utility Model Application Publication No. 1-16977
As disclosed in Publication No. 2, as shown in FIG. and a user-side heat exchanger (e) serving as a condenser are arranged indoors, and each of the above-mentioned devices (a) to (e) is sequentially connected through refrigerant piping to form a main refrigerant circuit (f). In the apparatus, a refrigerant cooling bypass passage (g) is provided to bypass connect the main refrigerant circuit (f) between the pressure reducing mechanism (c) and the receiver (d) and the suction pipe of the compressor (a). Refrigerant cooling bypass path (g
), and the refrigerant flowing through the downstream piping of the capillary tube (h) of the refrigerant cooling bypass path (g) and the liquid pipe immediately before the pressure reducing mechanism (c). A heat exchanger (i) is provided for exchanging heat with the refrigerant, and this heat exchanger (i) connects the refrigerant cooling bypass path (g).
The depressurized refrigerant in the capillary tube (h) exchanges heat with the liquid refrigerant in the main refrigerant circuit (f), and the pressure reducing mechanism (
c) It is a known technique that attempts to expand the refrigerating capacity by appropriately adjusting the specific volume of the liquid refrigerant by cooling the immediately preceding liquid refrigerant.

0003

[Problem to be solved by the invention] In the above conventional method,
The refrigerant flows as shown by the solid arrow in the figure, and the state of the refrigerant is as shown in the Mollier diagram of FIG. That is, the refrigerant flowing to the refrigerant cooling bypass path (g) is depressurized from ■ to the state shown in the figure, and then returns to the suction pipe in the state shown in ■. Then, in the heat exchanger (i), heat exchange is performed between the refrigerant in the state of ■ and the refrigerant in the state of ■, respectively.
As a result of the change in state, the refrigerant flowing through the pressure reducing mechanism (c) is cooled and its specific volume becomes smaller, and the refrigerant (■) flowing into the suction pipe becomes a wet gas. As a result, the refrigerant (■) has an increased specific volume due to pressure loss while passing through a long liquid pipe.
is reduced to its original state, so the pressure reduction flow rate control function in the pressure reduction mechanism (c) is maintained normally.On the other hand, on the suction side of the compressor (a), the superheated gas after passing through the heat source side heat exchanger (b) ■)
Due to the injection effect of the refrigerant (■), the temperature of the steam is lowered and becomes properly superheated steam, which is sucked into the compressor (a). In other words, since the temperature difference (Δt) between the refrigerants to be heat exchanged can be large, sufficient cooling can be achieved.

[0004] Incidentally, in recent years, there has been a demand for reducing the amount of refrigerant charged in air conditioners, and for this purpose it is necessary to reduce the diameter of the liquid piping. A problem arises.

[0005] That is, when the above-mentioned conventional system is applied to an air conditioner for both cooling and heating that is equipped with an outdoor pressure reducing mechanism and an indoor pressure reducing mechanism as pressure reducing mechanisms (particularly in the case of a so-called multi-type air conditioner), The refrigerant cooling bypass path (g) branches from the liquid pipe, but for example, during cooling operation, the refrigerant is depressurized by passing through an outdoor decompression mechanism, and the refrigerant pipe is thin, so there is a large pressure loss. 5, the refrigerant cooling bypass path (g
) The pressure in the refrigerant state (■) at the branch point with the refrigerant (■) will drop considerably as shown by the broken line arrow in the figure. therefore,
As the temperature difference (Δt) between the refrigerants to be heat exchanged becomes smaller, a so-called flash phenomenon occurs in which a part of the liquid refrigerant is gasified due to the increase in volume at the branch point with the refrigerant cooling bypass path (g), and the refrigerant There was a risk that the amount of refrigerant bypassed to the cooling bypass path (g) would become unstable. Also, when the flashed refrigerant flows into the refrigerant cooling bypass path (g),
There was a problem in that the refrigerant cooling effect by the heat exchanger (i) was further reduced because the pressure reduction mechanism (h) obstructed the flow.

[0006] The present invention has been made in view of the above points, and its object is to effectively prevent a decrease in cooling capacity and flash of the refrigerant caused by pressure loss accompanying the reduction in the diameter of refrigerant piping. By taking such measures, it is possible to ensure the cooling effect of the liquid refrigerant in the main refrigerant circuit, thereby making it possible to reduce the amount of refrigerant charged by reducing the diameter of the refrigerant piping.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the means taken by the invention of claim 1 are as shown in FIG.
Compressor (1), heat source side heat exchanger (3), outdoor pressure reduction mechanism (
4), a main refrigerant circuit (10) formed by sequentially connecting an indoor pressure reduction mechanism (6) and a user-side heat exchanger (7) with a refrigerant pipe (9);
Targets air conditioners equipped with

[0008] Furthermore, the air conditioner includes a heat source side heat exchanger (3) of the main refrigerant circuit (10) - an outdoor decompression mechanism (4).
A refrigerant cooling bypass path (11A) connects the liquid pipe and the suction line between the refrigerant cooling bypass paths (11A) and 11A.
1A), the refrigerant flowing through the piping downstream of the pressure reducing mechanism (13) of the refrigerant cooling bypass passage (11A), and each of the pressure reducing mechanisms (10) of the main refrigerant circuit (10). The structure includes a heat exchanger (12) for exchanging heat with the refrigerant flowing through the liquid pipe between 4) and (5).

The means taken by the invention of claim 2 is that, as shown in FIG.
A refrigerant cooling bypass path (11B) is provided to bypass-connect the branch liquid pipe (31a) and the suction line, and a pressure reducing mechanism (13) is interposed in the refrigerant cooling bypass path (11B).

Furthermore, the refrigerant cooling bypass passage (11
Heat exchange is performed between the refrigerant flowing through the piping on the downstream side of the pressure reduction mechanism (13) in B) and the refrigerant flowing through the liquid pipes between the pressure reduction mechanisms (4) and (5) of the main refrigerant circuit (10). A heat exchanger (12) is provided for this purpose.

As shown in FIG. 3, the means taken by the invention according to claim 3 is that, instead of the refrigerant cooling bypass passage (11A) in the invention according to claim 1, the discharge pipe and suction pipe of the compressor (1) are used. Bypass path for refrigerant cooling that bypasses the line (
11C), and the auxiliary heat exchanger (3a) of the heat source side heat exchanger (3) and the pressure reduction mechanism (13) are interposed in the refrigerant cooling bypass path (11C) in order from the upstream side.

Furthermore, the refrigerant cooling bypass passage (11
Heat exchange is performed between the refrigerant flowing through the piping on the downstream side of the pressure reducing mechanism (13) in C) and the refrigerant flowing through the liquid pipes between the pressure reducing mechanisms (4) and (5) of the main refrigerant circuit (10). A heat exchanger (12) is provided for this purpose.

The means taken by the invention of claim 4 is that in the invention of claim 1, 2 or 3, the discharge pipe of the compressor (1) and between the outdoor pressure reducing mechanism (4) and the indoor pressure reducing mechanism (6) are provided. A high-pressure control bypass path (20) is provided for bypass connection with the liquid pipe, and an on-off valve (21) is provided in the high-pressure control bypass path (20).
and a pressure reducing mechanism (22) for high pressure control.

The means taken by the invention of claim 5 is that in the invention of claim 1, 2 or 3, the main refrigerant circuit (10) is provided with a plurality of sets of user-side heat exchangers (6) and an indoor pressure reducing mechanism ( 5
) are arranged in parallel with each other.

[0015]

[Operation] With the above configuration, in the invention of claim 1, the refrigerant cooling bypass path (11A) is a liquid pipe between the heat source side heat exchanger (3) and the outdoor pressure reducing mechanism (4) of the main refrigerant circuit (10). Since the refrigerant is branched from the refrigerant, a part of the liquid refrigerant is diverted to the refrigerant cooling bypass path (11A) before being subjected to the decompression action by the outdoor decompression mechanism (4). In other words, since the pressure loss of the refrigerant is reduced, the increase in pressure loss due to the reduction in the diameter of the refrigerant piping is offset, and a sufficient temperature difference between the refrigerants heat exchanged in the heat exchanger (12) is ensured. Therefore, it is possible to improve the refrigeration effect and prevent overheating, and it is possible to reduce the amount of refrigerant charged by reducing the diameter of the refrigerant pipe.

In the invention of claim 2, during cooling operation, the refrigerant condensed and liquefied in the heat source side heat exchanger (3) flows through each branch liquid pipe (
31a), (31b), etc. Depending on the conditions, there is a risk of flash occurring due to an increase in the flow area, but the refrigerant cooling bypass path (11B) is a branch of the heat source side heat exchanger (3). Since it branches off from the liquid pipe (31a), it will not be affected by flash even under such conditions. Therefore, the refrigerant cooling effect in the heat exchanger (12) is maintained satisfactorily under wider conditions than in the invention of claim 1.

[0017] In the invention of claim 3, in the refrigerant cooling bypass path (11C), the auxiliary heat exchanger (3a) is
Since the liquid refrigerant in the liquid tube is cooled by heat exchange with the condensed and liquefied refrigerant, it is not affected by flash in the liquid tube of the main refrigerant circuit (10). That is, during cooling operation, the cooling effect of the refrigerant is reliably maintained even under wider changes in conditions than in the inventions of claims 1 and 2, and
During heating operation, the cooling effect of the liquid refrigerant is maintained even under conditions where the liquid refrigerant flowing from each of the indoor units (A) to (C) flashes excessively.

[0018] In the invention of claim 4, when the hot gas introduced through the high-pressure control bypass passage (20) at low outside air temperature during cooling operation mixes into the liquid pipe, the enthalpy of the refrigerant increases in the liquid pipe. Therefore, even if the cooling refrigerant is bypassed from the downstream side, there is a risk that the temperature difference necessary for cooling the refrigerant cannot be secured. Upstream side (outdoor decompression mechanism (4) downstream side) than the introduced part (outdoor decompression mechanism (4) downstream side)
4) Since the refrigerant is branched from the upstream side, the liquid refrigerant in the main refrigerant circuit (10) is cooled with refrigerant that does not introduce hot gas, and a stable cooling effect is maintained regardless of changes in operating conditions. be done.

[0019] In the invention of claim 5, especially in the case of a multi-type air conditioner, the refrigerant piping length is long, and if the refrigerant charging amount is reduced due to differences in the loads of each indoor unit, the refrigerant circulation amount tends to be insufficient. Although there is a high probability of flash occurring, the refrigerant cooling effect of the invention according to claim 1, 2 or 3 can be significantly obtained.

[0020]

[Example] The following is an example of the present invention in FIGS. 1 to 4.
The explanation will be based on.

FIG. 1 shows a refrigerant piping system of an air conditioner according to the first embodiment, in which three indoor units (A) to (C) are connected in parallel to one outdoor unit (X). It is configured in a multi-shape. The outdoor unit (X) includes a compressor (1) that compresses and discharges the sucked refrigerant;
A four-way switching valve (2) that switches connections as shown in the solid line in the figure during cooling operation and as shown in the broken line in the figure during heating operation, and a heat source side heat exchanger that functions as a condenser during cooling operation and as an evaporator during heating operation. (3) and an outdoor electric expansion valve (
4), a receiver (5) for storing liquid refrigerant, and an accumulator (8) for removing liquid refrigerant from the refrigerant sucked into the compressor (1) are arranged as main equipment. The above-mentioned devices are connected in series by a main refrigerant pipe (9).

On the other hand, each of the above indoor units (A) to (C)
have the same configuration, and each has a user-side heat exchanger (7) that functions as an evaporator during cooling operation and a condenser during heating operation, and an indoor heat exchanger (7) that reduces the pressure of the refrigerant during cooling operation and adjusts the refrigerant flow rate during heating operation. It is equipped with an indoor electric expansion valve (6) as a pressure reducing mechanism, and each indoor unit (A
) to (C), each device (6), (7) is connected to the main refrigerant pipe (
9) are interposed in branch pipes (9a) to (9c) branched from a liquid flow divider (14) and a gas flow divider (15) provided at both ends of the pipe. That is, each of the above devices (1) to (8
) are the main refrigerant pipe (9) and branch pipes (9a) to (9c)
The main refrigerant circuit (10) is connected in sequence to form a closed circuit, and in which the refrigerant circulates to cause heat transfer.
is configured.

Here, as a feature of the present invention, a portion (point (P)) on the liquid pipe between the heat source side heat exchanger (3) and the outdoor electric expansion valve (4) of the main refrigerant circuit (10) and a part (point (S)) on the suction line is the refrigerant cooling bypass path (11
A), and a first capillary tube (13) serving as a pressure reduction mechanism for reducing the pressure of the refrigerant is interposed in the refrigerant cooling bypass path (11A). And the piping on the downstream side of the first capillary tube (13) of the refrigerant cooling bypass path (11A), and the receiver (5) of the main refrigerant circuit (10) - the indoor electric expansion valve (6).
A heat exchanger (12) that stores the liquid pipes between the two in a common container.
is provided, and heat exchange is performed between the refrigerants in each pipe in the heat exchanger (12). That is, the liquid refrigerant in the liquid pipe of the main refrigerant circuit (10) is cooled by the refrigerant whose pressure is reduced in the first capillary tube (13) of the refrigerant cooling bypass path (11A).

In the air conditioner having the above configuration, during cooling operation, the connection of the four-way switching valve (2) is on the solid line side in the figure, and the refrigerant flows in the direction of the solid line arrow in the figure. That is,
A low-pressure gas refrigerant (■) sucked into the compressor (1) is discharged as a high-pressure refrigerant (■). Furthermore, it is condensed and liquefied in the heat source side heat exchanger (3) to become a high-pressure liquid refrigerant (■), which is depressurized by flow rate adjustment in the outdoor electric expansion valve (4) and stored in the receiver (5). Then, the refrigerant (■) that has passed through the heat exchanger (12) from the receiver (5) is transferred to the liquid flow divider (
14), the branch pipes (9a) to (9c) flow to each indoor unit (A) to (C), and each indoor electric expansion valve (6
) to become a low-pressure liquid refrigerant (■), it is evaporated in the heat exchanger (7) on the user side, and becomes a low-pressure gas refrigerant (■), which passes through the accumulator (8) and into the compressor (1). cycle back to . On the other hand, in the refrigerant cooling bypass path (11A),
Some refrigerant (■) branches from the main refrigerant circuit (10),
The refrigerant is depressurized in the first capillary tube (13) and becomes a low-pressure and low-temperature refrigerant (■), which passes through the heat exchanger (12) and joins the suction line as a refrigerant (■) whose temperature has increased. Moreover, during heating operation, the circulation is reversed.

At this time, in the above embodiment, the refrigerant cooling bypass path (11A) branches from the liquid pipe between the heat source side heat exchanger (3) and the outdoor electric expansion valve (4) of the main refrigerant circuit (10). Therefore, a part of the liquid refrigerant is diverted to the refrigerant cooling bypass passage (11A) before being subjected to the pressure reducing action by the outdoor electric expansion valve (4), thereby reducing pressure loss. That is, in the Mollier diagram of FIG. 5, the pressure of the refrigerant (■) at the branch part (point (P)) of the refrigerant cooling bypass path (11A) is increasing as indicated by the dotted line arrow in the diagram. Thereafter, even if the pressure is reduced by the outdoor pressure reducing mechanism (4) or intermediate piping (see the one-dot chain arrow in the figure), the above-mentioned rising effect is offset and the cooling effect is maintained satisfactorily. Therefore, even if the refrigerant piping is small in diameter, the heat exchanger (
In step 12), a sufficient temperature difference Δt between the refrigerants to be heat exchanged is ensured, and therefore, the refrigerant filling amount is reduced by reducing the diameter of the refrigerant pipe (9) while effectively securing the effect of improving the refrigerating capacity and preventing overheating operation. Therefore, it is possible to reduce the Also,
By the same effect, it is also possible to extend the length of the refrigerant pipe.

In the first embodiment, the air conditioner is used for both cooling and heating, but even in the case of a cooling-only unit, a pressure reducing mechanism is installed at the outlet of the heat exchanger (3) on the heat source side in order to adjust the refrigerant flow rate when the outside air temperature is low. Even in such a case, the present invention can exhibit the above-mentioned effects.

Next, a second embodiment will be explained based on FIG. 2. FIG. 2 shows the refrigerant piping system of the air conditioner in the second embodiment, and the configuration of the main refrigerant circuit (10) is the same as that of the first embodiment.
This is similar to the example. Here, in this embodiment, a branch liquid pipe (
One of the branch liquid pipes (31a), (31b), ...
A refrigerant cooling bypass path (11B) is provided between a portion (point (Q)) of a) and a point (S) on the suction line. In addition, the discharge pipe of the compressor (1) and the main refrigerant circuit (10)
A high pressure control bypass path (20) is provided between the outdoor electric expansion valve (4) and the liquid pipe between the receiver (5). , an on-off valve (21) for opening and closing the bypass path (20), and a second capillary tube (22) are provided. That is, when the outside air is low during cooling operation, a portion of the hot gas is bypassed to the liquid pipe side to prevent the pressure on the high pressure side from rising excessively. The other configurations are the same as those of the first embodiment.

Therefore, in the second embodiment, during cooling operation, the refrigerant condensed and liquefied in the heat source side heat exchanger (3) is transferred from each branch liquid pipe (31a), (31b), . . .
) When flowing to the outlet, depending on the conditions, there is a possibility that a flash may occur due to an increase in the flow area. Therefore, even under such conditions, it will not be affected by flash. That is,
The cooling effect in the heat exchanger (12) is maintained well,
The effects of the first embodiment can be maintained.

In particular, in the case where a bypass passage (20) is provided for high pressure control when the outside air is low during cooling operation, the enthalpy of the refrigerant becomes large in the liquid pipe mixed with hot gas, so the cooling refrigerant is removed from the downstream side of the liquid pipe. Even if it is bypassed, it will not be possible to secure a sufficient temperature difference Δt as shown in FIG. 5 above. On the other hand, in the second embodiment,
The outdoor electric expansion valve (4) where hot gas is introduced is more upstream than the downstream side (outdoor electric expansion valve (4) during cooling operation)
Since the liquid refrigerant in the main refrigerant circuit (10) is cooled by the refrigerant branched from the upstream side, the above-mentioned problems do not occur, and therefore a stable cooling amount can be ensured regardless of changes in operating conditions. can.

Next, a third embodiment will be explained based on FIG. 3. FIG. 3 shows a refrigerant piping system of an air conditioner according to the third embodiment. A bypass path (11C) is provided. and,
This refrigerant cooling bypass path (11C) is provided with an auxiliary heat exchanger (3a) disposed in a common air passage with the heat source side heat exchanger (3), and downstream of the auxiliary heat exchanger (3a).
The first capillary tube (13
) and a heat exchanger (12).

Therefore, in the third embodiment, in the refrigerant cooling bypass path (11C), the main refrigerant circuit (10)
The liquid refrigerant in the liquid pipes is cooled by heat exchange with the refrigerant condensed and liquefied in the auxiliary heat exchanger (3a) without bypassing the refrigerant from the liquid pipes in the main refrigerant circuit (10). It is not affected by flash in the tube. That is, the cooling effect of the refrigerant can be reliably maintained even under wide changes in operating conditions. Furthermore, in this embodiment, the liquid refrigerant is not used not only during cooling operation but also under conditions where the liquid refrigerant flowing from each indoor unit (A) to (C) flashes excessively during heating operation. It has the advantage that it can be cooled to reduce its specific volume.

Note that the present invention is not limited to multi-type air conditioners as in the above embodiments, but in particular, in the case of multi-type air conditioners, the refrigerant piping length is long and the load of each indoor unit is small. If the amount of refrigerant charged is reduced due to differences in the amount of refrigerant, the amount of refrigerant circulated may become insufficient, increasing the probability of flash occurring, but by applying the present invention, the occurrence of flash can be effectively prevented as described above. Therefore, it can be highly effective.

[0033]

As explained above, according to the invention of claim 1, the configuration of the air conditioner includes a compressor, a heat source side heat exchanger, an outdoor pressure reducing mechanism, an indoor pressure reducing mechanism, and a user side heat exchanger. The main refrigerant circuit is formed by sequentially connecting refrigerant piping, and the liquid pipe between the heat source side heat exchanger of the main refrigerant circuit and the outdoor decompression mechanism and the suction line are connected via the refrigerant cooling bypass path through the decompression mechanism. A heat exchanger is provided to exchange heat between the refrigerant flowing through the piping on the downstream side of the pressure reducing mechanism in the refrigerant cooling bypass and the refrigerant flowing through the liquid pipes between the pressure reducing mechanisms in the main refrigerant circuit. Therefore, by diverting a portion of the liquid refrigerant to the refrigerant cooling bypass path before receiving the depressurization action by the outdoor depressurization mechanism, flashing in the liquid pipes due to increased pressure loss due to the smaller diameter of the refrigerant pipes can be avoided. Therefore, it is possible to reduce the diameter of the refrigerant pipe and extend the length of the refrigerant pipe while maintaining the effect of improving the refrigerating capacity and preventing the overheating operation by the refrigerant cooling bypass passage.

According to the invention of claim 2, since the refrigerant cooling bypass path in the structure of the invention of claim 1 is branched from the branch liquid pipe of the heat exchanger on the heat source side, The refrigerant in the liquid pipes of the main refrigerant circuit can be cooled without being affected by the flash that occurs when the condensed and liquefied refrigerant flows out from each branch liquid pipe, and therefore, the conditions are broader than the invention of claim 1. Under this condition, the refrigerant cooling effect in the heat exchanger can be maintained well.

According to the third aspect of the present invention, the refrigerant cooling bypass path in the configuration of the first aspect of the invention is branched from the discharge pipe, and the bypass path is further connected to the auxiliary heat exchanger of the heat exchanger on the heat source side. As a result, the liquid refrigerant in the liquid pipes can be cooled with the liquid refrigerant condensed and liquefied in the auxiliary heat exchanger without being affected by flash in the liquid pipes of the main refrigerant circuit. Claim 1 or 2 while driving
It is possible to reliably maintain the cooling effect of the refrigerant even under a wider range of conditions than the invention of the invention, and even during heating operation, the liquid refrigerant is maintained regardless of the state of the liquid refrigerant flowing from the user-side heat exchanger in each room. The cooling effect of the refrigerant can be maintained.

According to the invention of claim 4, the above-mentioned claim 1,
In the invention of 2 or 3, the discharge pipe of the compressor and the liquid pipe between the outdoor pressure reducing mechanism and the indoor pressure reducing mechanism are bypass-connected by the high pressure control bypass path via the on-off valve and the high pressure control pressure reducing mechanism. , when the outside air temperature is low during cooling operation,
It is possible to secure the temperature difference necessary for cooling the refrigerant without being affected by the increase in enthalpy of the refrigerant due to the mixing of hot gas introduced via the high-pressure control bypass path, and therefore changes in operating conditions Regardless of the temperature, a stable cooling effect is maintained.

[0037] In the invention of claim 5, the above-mentioned claims 1, 2,
Or in invention 3, since multiple sets of indoor pressure reduction mechanisms and user-side heat exchangers are arranged in parallel in the main refrigerant circuit, the refrigerant piping length is long, and the refrigerant circulation amount tends to be insufficient as the refrigerant filling amount decreases. Even in air conditioners that are prone to failure, the occurrence of flash can be prevented, and the above-mentioned inventions can therefore exhibit significant effects.

[Brief explanation of drawings]

FIG. 1 is a refrigerant piping system diagram of an air conditioner according to a first embodiment.

FIG. 2 is a refrigerant piping system diagram of an air conditioner according to a second embodiment.

FIG. 3 is a refrigerant piping system diagram of an air conditioner according to a third embodiment.

FIG. 4 is a refrigerant piping system diagram of an air conditioner according to the prior art.

FIG. 5 is a Mollier diagram showing changes in the refrigerant state in the air conditioner.

[Explanation of symbols]

1 Compressor 3 Heat source side heat exchanger 4 Outdoor electric expansion valve (outdoor pressure reduction mechanism) 6
Indoor electric expansion valve (indoor pressure reducing mechanism) 7 Usage side heat exchanger 9 Refrigerant piping 10 Main refrigerant circuit 11 Refrigerant cooling bypass path 12 Heat exchanger 13 First capillary tube (pressure reducing mechanism) 20
Bypass path 21 for high pressure control On-off valve 22 Pressure reducing mechanism 31a for high pressure control Diversion liquid pipe

Claims (5)

[Claims] [Claim 1] Compressor (1), heat source side heat exchanger (3)
, an air conditioner comprising a main refrigerant circuit (10) in which an outdoor pressure reducing mechanism (4), an indoor pressure reducing mechanism (6) and a user-side heat exchanger (7) are sequentially connected by a refrigerant pipe (9). , a refrigerant cooling bypass passage (11A) that bypass-connects the suction line and the liquid pipe between the heat source side heat exchanger (3) and the outdoor pressure reducing mechanism (4) of the main refrigerant circuit (10); A pressure reduction mechanism (13) interposed in the bypass path (11A) and a pressure reduction mechanism (13) in the refrigerant cooling bypass path (11A).
Refrigerant flowing through the downstream piping and the main refrigerant circuit (10)
An air conditioner comprising: a heat exchanger (12) for exchanging heat with a refrigerant flowing through liquid pipes between the pressure reducing mechanisms (4) and (5). [Claim 2] Compressor (1), heat source side heat exchanger (3)
, an air conditioner comprising a main refrigerant circuit (10) in which an outdoor pressure reducing mechanism (4), an indoor pressure reducing mechanism (6) and a user-side heat exchanger (7) are sequentially connected by a refrigerant pipe (9). , a refrigerant cooling bypass path (11B) that bypass-connects the branch liquid pipe (31a) of the heat source side heat exchanger (3) and the suction line.
), a pressure reducing mechanism (13) interposed in the refrigerant cooling bypass path (11B), and the refrigerant cooling bypass path (11B).
Heat exchange is performed between the refrigerant flowing through the piping on the downstream side of the pressure reducing mechanism (13) in B) and the refrigerant flowing through the liquid pipes between the pressure reducing mechanisms (4) and (5) of the main refrigerant circuit (10). An air conditioner characterized by comprising a heat exchanger (12) for carrying out. [Claim 3] Compressor (1), heat source side heat exchanger (3)
, an air conditioner comprising a main refrigerant circuit (10) in which an outdoor pressure reducing mechanism (4), an indoor pressure reducing mechanism (6) and a user-side heat exchanger (7) are sequentially connected by a refrigerant pipe (9). , a refrigerant cooling bypass passage (11C) that bypass-connects the discharge pipe and suction line of the compressor (1), and the heat source side heat exchanger (
3) the auxiliary heat exchanger (3a), the pressure reduction mechanism (13) interposed on the downstream side of the auxiliary heat exchanger (3a) of the refrigerant cooling bypass path (11C), and the refrigerant cooling bypass path (11) Pressure reducing mechanism (13) The refrigerant flowing through the downstream piping and each pressure reducing mechanism (4), (
5) A heat exchanger (12) for exchanging heat with a refrigerant flowing through a liquid pipe between the air conditioners. 4. The air conditioner according to claim 1, 2 or 3, wherein the discharge pipe of the compressor (1) and the outdoor pressure reducing mechanism (4
) and the indoor pressure reducing mechanism (6), a high pressure control bypass path (20) is provided, and the high pressure control bypass path (20) has an on-off valve (21) and a high pressure control An air conditioner characterized by being provided with a pressure reducing mechanism (22). 5. The air conditioner according to claim 1, 2 or 3, wherein in the main refrigerant circuit (10), a plurality of sets of user-side heat exchangers (6) and indoor pressure reducing mechanisms (5) are arranged in parallel with each other. An air conditioner characterized by: