JPH10148412A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive refrigerating system which can selection an inject operation or a non-injection operation of an intermediate pressure refrigerant optionally. SOLUTION: A bypass path 10 is provided between a room heat exchanger 3 and a second expansion valve 5. A piping 25 on the downstream side of the room heat exchanger 3, a piping 26 on the upstream side of a first expansion valve 4 and a piping 27 on the upstream side of the bypass path 10 are connected together by a rotary type tree-way valve 18. The rotary type three-way valve 18 is so arranged to make a communication between the piping 25 and the piping 26 only in the injection operation and between the piping 25 and the piping 27 only in the non-injection operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a refrigeration apparatus,
In particular, the present invention relates to a refrigerating apparatus provided with an intermediate pressure refrigerant injection circuit.

[0002]

2. Description of the Related Art Conventionally, there has been known a refrigerating apparatus for injecting an intermediate-pressure gas refrigerant into a compressor for the purpose of improving the capacity of a condenser. For example, Japanese Patent Application Laid-Open No. 4-1
No. 77062 discloses a refrigerating apparatus as shown in FIG. This refrigerating device includes a compressor (a), a four-way switching valve (b), an indoor heat exchanger (c), a gas-liquid separator (d), and a pressure reducer (g1).
To (g4) and an outdoor heat exchanger (e). The refrigeration apparatus is provided with a so-called bridge circuit (f) including check valves (i1) and (i2). The gas-liquid separator (d) and the compressor (a) are connected by an outlet pipe (h).

In the above refrigeration system, during heating, the refrigerant circulates in the direction indicated by the dashed arrow in FIG. Pressure reducer (g1) and (g3)
The refrigerant decompressed from high pressure to intermediate pressure in the gas-liquid separator (d)
And is separated into a gas refrigerant and a liquid refrigerant. The liquid refrigerant is supplied to the check valve (i
After passing through 2), the pressure is reduced from the intermediate pressure to a low pressure by the pressure reducer (g2). On the other hand, the gas refrigerant is sucked into the compressor (a) through the outlet pipe (h). As a result, the circulation amount of the gas refrigerant flowing through the condenser (c) increases, and the heating capacity is improved.

On the other hand, during cooling, the four-way switching valve (b) is switched, and the refrigerant circulates in the direction indicated by the solid line arrow. The refrigerant condensed in the outdoor heat exchanger (e) is reduced in pressure from high pressure to an intermediate pressure by the decompressors (g2) and (g4), flows into the gas-liquid separator (d), and flows into the gas-liquid separator (d). And is separated into a gas refrigerant and a liquid refrigerant. The liquid refrigerant passes through the check valve (i1), is reduced in pressure from the intermediate pressure to a low pressure by the pressure reducer (g1), and evaporates in the indoor heat exchanger (c). On the other hand, the gas refrigerant is supplied to the compressor through the outlet pipe (h).
Inhaled in (a).

[0005] As described above, in the refrigerating apparatus, the injection operation is performed during both heating and cooling.

Further, Japanese Utility Model Laid-Open Publication No. 58-28254 discloses a refrigeration apparatus that performs only an injection operation during heating and performs only a non-injection operation during cooling.

[0007]

In recent years, in view of global environmental problems such as destruction of the ozone layer, a transition from a conventional refrigerant such as R22 to an alternative refrigerant has been made. At present, as an alternative refrigerant, R4
There is a refrigerant called 10A. R410A is R32
It is a mixed refrigerant of (difluoromethane) and R125 (pentafluoroethane). R410A has a characteristic that the amount of change in latent heat with respect to a temperature change is larger than that of R22. In this specification, “latent heat” means the difference between the enthalpy of saturated vapor and the enthalpy of saturated liquid per unit mass at a constant temperature.

Referring to FIG. 5, R410A and R22
The amount of change in latent heat due to the temperature change will be described. FIG.
Is the specific enthalpy (kJ / kg) on the horizontal axis and the temperature (° C) on the vertical axis
The solid line shows the saturation curve of R410A, and the broken line shows the saturation curve of R22. In the case of R22, when the condensation temperature increases from T (° C.) to T ′ (° C.), the amount of change in latent heat is ΔIa = Ia−Ia ′, which is a small value.
On the other hand, in the case of R410A, the amount of change in latent heat is ΔIb = I
b−Ib ′, which is a large value. Therefore, R41
When 0 A is used, it becomes difficult to secure a necessary enthalpy difference as the condensation temperature increases. In that case, it is necessary to increase the amount of circulating refrigerant flowing through the condenser. On the other hand, when the condensing temperature is low, a sufficient enthalpy difference can be ensured, so that it is not necessary to increase the circulation amount of the refrigerant flowing through the condenser.

However, in the above-mentioned conventional refrigeration system, only one of the injection operation and the non-injection operation can be performed. Therefore, if the injection operation is performed, an inefficient operation is performed when the condensation temperature is low. On the other hand, if the non-injection operation is performed, the amount of heat of condensation is insufficient when the condensation temperature is high. Therefore, efficient operation according to the condensation temperature was impossible.

[0010] Even when a refrigerant having a small change in latent heat with respect to a temperature change is used, it is preferable that the injection operation can be switched because more efficient operation can be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and an object thereof is to perform any operation of a cooling operation and a heating operation by switching between an injection operation and a non-injection operation arbitrarily. It is an object of the present invention to provide a refrigeration apparatus that can perform the refrigeration.

[0012]

In order to achieve the above object, the present invention provides a bypass passage (10) which can be closed between a use side heat exchanger (3) and a second pressure reducing mechanism (5). It was decided to provide.

[0013] More specifically, the means adopted by the first aspect of the present invention includes a compressor (1), a use side heat exchanger (3), a first pressure reducing mechanism (4), and a gas-liquid separation device. Vessel (6), second pressure reducing mechanism (5),
A heat source side heat exchanger (7) is provided in order, and the gas refrigerant separated by the gas-liquid separator (6) is compressed between the gas-liquid separator (6) and the compressor (1). In a refrigerating apparatus provided with an injection passage (11) for injecting into the machine (1), an on-off valve is provided between the use side heat exchanger (3) and the second pressure reducing mechanism (5).
The bypass passage (10) provided with (SV-1) is provided in parallel with the first pressure reducing mechanism (4) and the gas-liquid separator (6).

According to the above features of the invention, it is possible to arbitrarily select either the injection operation or the non-injection operation by opening and closing the on-off valve (SV-1).

Means taken by the invention according to claim 2 are a compressor (1), a use side heat exchanger (3), and a first pressure reducing mechanism (4).
, A gas-liquid separator (6), a second pressure reducing mechanism (5), and a heat source side heat exchanger (7), and the gas-liquid separator (6) and the compressor (1)
And an injection passage for injecting the gas refrigerant separated by the gas-liquid separator (6) into the compressor (1).
In the refrigeration system provided with (11), the second pressure reducing mechanism
One end of a bypass passage (10) is connected between (5) and the gas-liquid separator (6), and the other end of the bypass passage (10) is connected to a use side heat exchanger (3) by a three-way valve (18). The three-way valve (18) is connected between the use-side heat exchanger (3) and the bypass passage (10) and the use-side heat exchanger ( A state in which the third pressure reducing mechanism (4) communicates with the first pressure reducing mechanism (4);
And a state in which the bypass passage (10) is in communication with the bypass passage (10).

According to the above-mentioned specific features of the invention, it is possible to arbitrarily select either the injection operation or the non-injection operation with a simpler configuration.

According to a third aspect of the present invention, in the refrigeration apparatus according to the second aspect, the three-way valve is constituted by a rotary three-way valve (18).

According to the above-mentioned specific features of the invention, it is possible to arbitrarily select either the injection operation or the non-injection operation with a more specific configuration.

According to a fourth aspect of the present invention, there is provided the refrigeration apparatus according to any one of the first and second aspects, wherein the refrigerant has an amount of change in latent heat with respect to temperature change of R22.
In this configuration, a refrigerant having a characteristic larger than a change in latent heat with respect to a temperature change is used.

According to the present invention, the effect of arbitrarily selecting either the injection operation or the non-injection operation can be more remarkably exhibited.

[0021]

Embodiment 1 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

-Configuration of Air Conditioner (30)-As shown in FIG. 1, the refrigeration apparatus according to Embodiment 1 is a heat pump type air conditioner (30), which is mainly composed of an outdoor unit (20) and an indoor unit. And a unit (21). The outdoor unit (20) includes a compressor (1), a four-way switching valve (2), a first expansion valve (4) as a first pressure reducing mechanism, a second expansion valve (5) as a second pressure reducing mechanism, A liquid separator (6), an outdoor heat exchanger (7) as a heat source side heat exchanger, an accumulator (8), an injection passage (11) provided with a first solenoid valve (SV-1), and a second electromagnetic Valve (S
A bypass passage (10) provided with V-2) is provided. A first closing valve (14) and a second closing valve (15) are provided at an end of the refrigerant pipe of the outdoor unit (20). On the other hand, the indoor unit (21) includes an indoor heat exchanger (3) that is a use-side heat exchanger.

The outdoor unit (20) and the indoor unit (21) are connected through a refrigerant pipe. This connection connects the refrigerant pipes of the outdoor unit (20) and the indoor unit (21) in which the refrigerant R410A is sealed and filled in advance,
After performing a predetermined installation work, the first closing valve (14) and the second closing valve (15) are opened. By connecting the outdoor unit (20) and the indoor unit (21) in this manner, an air conditioner (30) having the following refrigerant circuit is configured.

The air conditioner (30) has a main refrigerant circuit provided with an injection passage (11) and a bypass passage (10). The main refrigerant circuit consists of a compressor (1), a four-way switching valve (2), an indoor heat exchanger (3), a first expansion valve (4), and a gas-liquid separator.
(6), the second expansion valve (5) and the outdoor heat exchanger (7) are connected in order. The injection passage (11) is disposed between the gas-liquid separator (6) and the compressor (1), and is provided with a second solenoid valve (SV-2) as an on-off valve. Bypass passage (1
0) is a pipe (1) between the indoor heat exchanger (3) and the first expansion valve (4).
6) and a pipe (17) between the gas-liquid separator (6) and the second expansion valve (5)
And connected to. The bypass passage (10) is provided with a first solenoid valve (SV-1) as an on-off valve.

The first expansion valve (4) and the second expansion valve (5) are pressure reducing mechanisms whose opening can be freely adjusted.

-Operation of air conditioner (30)-In the air conditioner (30), non-injection heating operation,
Four types of operation are possible: an injection heating operation, a non-injection cooling operation, and an injection cooling operation. Hereinafter, each operation will be described.

-Non-Injection Heating Operation- The non-injection heating operation is an operation performed when the condensing temperature in the indoor heat exchanger (3) is relatively low.

During the non-injection heating operation, the first solenoid valve (SV-1) is open, the second solenoid valve (SV-2) is closed, and the first expansion valve (4) is fully closed. Is set to The degree of opening of the second expansion valve (5) is set slightly closed so that the high-pressure refrigerant is changed to the low-pressure refrigerant. The four-way switching valve (2) is switched to the broken line side shown in FIG.

As indicated by the dashed arrows, the high-pressure refrigerant discharged from the compressor (1) flows into the indoor heat exchanger (3) after passing through the four-way switching valve (2). The high-pressure refrigerant is condensed in the indoor heat exchanger (3) and heats indoor air. The condensed liquid refrigerant flows out of the indoor heat exchanger (3) and then flows through the bypass passage (10). At this time, since the first expansion valve (4) is closed, the refrigerant does not flow through the first expansion valve (4). And the bypass passage
The refrigerant that has passed through (10) is reduced in pressure from high pressure to low pressure by the second expansion valve (5), and becomes a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant evaporates in the outdoor heat exchanger (7). After passing through the four-way switching valve (2), the low-pressure refrigerant flows into the accumulator (8). Then, the refrigerant in the accumulator (8) is sucked into the compressor (1). As described above, the refrigerant circulates through the refrigerant circuit to heat the room.

-Injection heating operation- The injection heating operation is an operation performed when the condensing temperature in the indoor heat exchanger (3) is relatively high. In the present air conditioner (30), the condensation temperature is a predetermined value, for example, 36
It is set so that the injection heating operation is performed when the temperature exceeds ℃. Therefore, even when the above-described non-injection heating operation is being performed, the operation mode is switched from the non-injection heating operation to the injection heating operation when the condensing temperature becomes equal to or higher than the predetermined value.

During the injection heating operation,
The first solenoid valve (SV-1) is set to a closed state, and the second solenoid valve (SV-2) is set to an open state. The opening degree of the first expansion valve (4) is set slightly open so as to reduce the high-pressure refrigerant to a predetermined intermediate pressure, and the opening degree of the second expansion valve (5) decreases the intermediate-pressure refrigerant. It is set slightly open. The four-way switching valve (2)
It is set on the broken line side shown in FIG.

As shown by the dashed arrows, the high-pressure refrigerant discharged from the compressor (1) flows into the indoor heat exchanger (3) after passing through the four-way switching valve (2). The high-pressure refrigerant is condensed in the indoor heat exchanger (3) and heats indoor air. After flowing out of the indoor heat exchanger (3), the condensed liquid refrigerant passes through the first expansion valve (4) without passing through the bypass passage (10). At this time, the first
The pressure is reduced from a high pressure to a predetermined intermediate pressure by the expansion valve (4),
It becomes an intermediate-pressure two-phase refrigerant. The intermediate-pressure two-phase refrigerant flows into the gas-liquid separator (6), and is separated into an intermediate-pressure gas refrigerant and a liquid refrigerant.

The intermediate-pressure liquid refrigerant is reduced in pressure from the intermediate pressure to a low pressure by the second expansion valve (5) to become a low-pressure two-phase refrigerant. Then, the low-pressure two-phase refrigerant evaporates in the outdoor heat exchanger (7). The low-pressure refrigerant flowing out of the outdoor heat exchanger (7) passes through the four-way switching valve (2), passes through the accumulator (8), and is sucked into the compressor (1).

On the other hand, the intermediate-pressure gas refrigerant in the gas-liquid separator (6) passes through the injection passage (11) through the compressor (1).
Inhaled.

The intermediate-pressure gas refrigerant sucked into the compressor (1) is mixed and compressed with the low-pressure gas refrigerant, becomes a high-pressure gas refrigerant, and is discharged from the compressor (1).

As described above, the refrigerant circulates through the refrigerant circuit to heat the room. In the injection heating operation, the refrigerant circulation amount in the condenser is increased by injecting the intermediate-pressure gas refrigerant into the compressor (1).

-Non-Injection Cooling Operation- Next, the cooling operation will be described. The cooling operation is performed by switching the four-way switching valve (2) to reverse the circulation direction of the refrigerant. First, the non-injection cooling operation will be described.

The non-injection cooling operation is an operation performed when the condensation temperature in the outdoor heat exchanger (7) is relatively low.

During the non-injection cooling operation, the first solenoid valve (SV-1) is open, the second solenoid valve (SV-2) is closed, and the first expansion valve (4) is fully closed. Is set to The degree of opening of the second expansion valve (5) is set slightly closed so that the high-pressure refrigerant is changed to the low-pressure refrigerant. The four-way switching valve (2) is switched to the solid line side shown in FIG.

As shown by the solid arrows in FIG. 1, the compressor (1)
The high-pressure refrigerant discharged from is passed through the four-way switching valve (2),
It flows into the outdoor heat exchanger (7). The high-pressure refrigerant is condensed in the outdoor heat exchanger (7). After the condensed high-pressure liquid refrigerant flows out of the outdoor heat exchanger (7), the high-pressure liquid refrigerant is reduced in pressure from high pressure to low pressure in the second expansion valve (5), and becomes a low-pressure two-phase refrigerant. And
The low-pressure two-phase refrigerant passes through the bypass passage (10) without passing through the gas-liquid separator (6), evaporates in the indoor heat exchanger (3),
Cool indoor air. After the low-pressure refrigerant flowing out of the indoor heat exchanger (3) passes through the four-way switching valve (2), the accumulator (8)
Flows into. Then, the refrigerant in the accumulator (8) is sucked into the compressor (1). As described above, the refrigerant circulates through the refrigerant circuit, and the room is cooled.

-Injection Cooling Operation- The injection cooling operation is an operation performed when the condensation temperature in the outdoor heat exchanger (7) is relatively high. Similarly to the injection heating operation, the injection cooling operation is performed when the condensing temperature becomes equal to or higher than a predetermined value. Therefore, even when the non-injection cooling operation is being performed, the operation mode is switched from the non-injection cooling operation to the injection cooling operation when the condensing temperature becomes equal to or higher than the predetermined value.

In the injection cooling operation,
The first solenoid valve (SV-1) is set to a closed state, and the second solenoid valve (SV-2) is set to an open state. The opening degree of the second expansion valve (5) is set slightly open so as to reduce the high-pressure refrigerant to a predetermined intermediate pressure, and the opening degree of the first expansion valve (4) also reduces the intermediate-pressure refrigerant to a low pressure. It is set slightly open. The four-way switching valve (2)
It is set on the solid line side shown in FIG.

The high-pressure refrigerant discharged from the compressor (1) passes through the four-way switching valve (2) and is condensed in the outdoor heat exchanger (7). After flowing out of the outdoor heat exchanger (7), the condensed high-pressure liquid refrigerant is reduced in pressure from a high pressure to a predetermined intermediate pressure by the second expansion valve (5), and becomes an intermediate-pressure two-phase refrigerant. The intermediate-pressure two-phase refrigerant flows into the gas-liquid separator (6) without passing through the bypass passage (10), and is separated into an intermediate-pressure gas refrigerant and a liquid refrigerant.

The intermediate-pressure liquid refrigerant in the gas-liquid separator (6) is further reduced in pressure from the intermediate pressure to a low pressure when passing through the first expansion valve (4) to become a low-pressure two-phase refrigerant. Then, the low-pressure two-phase refrigerant flows into the indoor heat exchanger (3). The low-pressure two-phase refrigerant evaporates in the indoor heat exchanger (3) and cools indoor air. Then, the low-pressure refrigerant flowing out of the indoor heat exchanger (3) passes through the four-way switching valve (2), passes through the accumulator (8), and is sucked into the compressor (1).

On the other hand, the intermediate-pressure gas refrigerant in the gas-liquid separator (6) passes through the injection passage (11) to the compressor (1).
Inhaled.

As described above, the refrigerant circulates through the refrigerant circuit to cool the room. In the injection cooling operation, the medium-pressure gas refrigerant is injected into the compressor (1), thereby increasing the amount of refrigerant circulating in the outdoor heat exchanger (7), which is the heat source-side heat exchanger, resulting in insufficient heat absorption on the heat source side. Has been eliminated.

-Effects of Air Conditioning Apparatus (30)-As described above, the air conditioning apparatus (30) can not only arbitrarily select either the heating operation or the cooling operation, but also perform the heating operation and the cooling operation. For each of the operations, either the injection operation or the non-injection operation can be arbitrarily performed.

Therefore, even when the condensing temperature rises and a sufficient enthalpy difference cannot be secured in the non-injection operation, the required capacity can be provided by performing the injection operation to increase the refrigerant circulation amount. On the other hand, when the condensing temperature is not so high, by performing the non-injection operation, the load on the compressor (1) is reduced, and efficient operation becomes possible.

As a result, the air conditioner (30) exhibits an effect of enabling efficient operation according to the condensation temperature. In particular, when a refrigerant having a characteristic in which the amount of change in latent heat with respect to a temperature change is large, such as R410A, is used, the above effect is more remarkably exhibited.

[0050]

Embodiment 2 of the Invention-Configuration of Air Conditioner (31)-As shown in Fig. 2, an air conditioner (31) of
Among the air conditioners (30) of the first embodiment, the indoor heat exchanger
A pipe (25) on the downstream side of (3), a pipe (26) on the upstream side of the first expansion valve (4), and a pipe (27) on the upstream side of the bypass passage (10) are connected to a rotary three-way valve ( Connected in 18). here,
The upstream side refers to the case where the indoor heat exchanger (3) is used as a condenser, that is, the direction in which refrigerant flows from the compressor (1) through the indoor heat exchanger (3) to the second expansion valve (5). Means the upstream side of the flow of the refrigerant. The rotary three-way valve (18)
The valve communicates any one set of the pipe (25) and the pipe (26), the pipe (26) and the pipe (27), or the pipe (27) and the pipe (25).

In the air conditioner (31), Embodiment 1
Unlike the air conditioner (30), the solenoid valve (SV-1) is not provided in the bypass passage (10), and the second closing valve (15) is not provided downstream of the indoor heat exchanger (3).

Other configurations are the same as those of the air conditioner of the first embodiment.
Since this is the same as (30), the same reference numerals as in the first embodiment are assigned and the description thereof is omitted.

-Operation of air conditioner (31)-In the air conditioner (31), similarly to the air conditioner (30) of the first embodiment, non-injection heating operation, injection heating operation, non-injection cooling operation, And four types of operation of injection cooling operation are possible. The air conditioner (30) according to the first embodiment differs from the air conditioner (30) in that the air conditioner (31) switches between the injection operation and the non-injection operation by switching the rotary three-way valve (18) instead of the first solenoid valve (SV-1). ). The details of each driving operation are the same as those in the first embodiment, and thus description thereof will be omitted. Hereinafter, setting states of various valves in each operation mode will be described.

In the non-injection heating operation,
The four-way switching valve (2) is set on the broken line side in FIG.
(SV-2) is set to the closed state. Rotary three-way valve (18)
As shown in FIG. 3A, is set to a state where the opening (A) and the opening (B) communicate with each other, that is, a state where the pipe (25) and the pipe (27) communicate. Therefore, the refrigerant flows through the bypass passage (10) without passing through the gas-liquid separator (6). Second expansion valve (5)
Is set to be slightly squeezed so as to reduce the high-pressure refrigerant to a predetermined low pressure as in the first embodiment.

In the injection heating operation, the four-way switching valve (2) is set on the broken line side in FIG. 2 and the second solenoid valve (SV
-2) is set to the open state. As shown in FIG. 3B, the rotary three-way valve (18) is set so that the opening (A) and the opening (C) communicate with each other, that is, the pipe (25) and the pipe (26) communicate with each other. Is done. Therefore, the refrigerant flows into the gas-liquid separator (6),
It does not flow to the bypass passage (10). The first expansion valve (4) is set to reduce the high-pressure refrigerant to a predetermined intermediate pressure. Second
The expansion valve (5) is set slightly open so as to reduce the intermediate-pressure refrigerant to a predetermined low pressure.

In the non-injection cooling operation,
The four-way switching valve (2) is set on the solid line side in FIG.
(SV-2) is set to the closed state. Rotary three-way valve (18)
The second expansion valve (5) is set in the same manner as in the non-injection heating operation. That is, as shown in FIG. 3A, the rotary three-way valve (18) is set so that the opening (A) and the opening (B) communicate with each other, and the second expansion valve (5) supplies high-pressure refrigerant. The pressure is set to be slightly squeezed so as to reduce the pressure to a predetermined low pressure.
Therefore, the refrigerant flows through the bypass passage (10) without passing through the gas-liquid separator (6).

In the injection cooling operation, the four-way switching valve (2) is set on the solid line side in FIG. 2 and the second solenoid valve (SV
-2) is set to the open state. The rotary three-way valve (18) and the second expansion valve (5) are set in the same manner as in the injection heating operation. In other words, the rotary three-way valve (18)
As shown in (b), the opening (A) and the opening (C) are set to communicate with each other. Therefore, the refrigerant flows into the gas-liquid separator (6) and does not pass through the bypass passage (10). The second expansion valve (5) is set slightly open so as to reduce the high-pressure refrigerant to a predetermined intermediate pressure. The first expansion valve (4) is set to reduce the intermediate-pressure refrigerant to a predetermined low pressure.

-Effect of air conditioner (31)-Accordingly, the air conditioner (31) of the second embodiment is different from that of the first embodiment.
Exactly the same effect as that of the air conditioner (30) can be achieved. Further, in the air conditioner (31) of the second embodiment, the following effects can be obtained.

In the air conditioner (31), the use of the rotary three-way valve (18) eliminates the need for the first solenoid valve (SV-1). Further, the second closing valve (15) is not required. That is,
Before installation of the air conditioner (31) as at the time of factory shipment, the rotary three-way valve (18) is set so that the opening (B) and the opening (C) are in communication with each other, and the first shut-off valve is provided. By closing (14), the outdoor unit (20) can be charged with the refrigerant in advance. Therefore, the first solenoid valve (SV-
Since the two devices of 1) and the second closing valve (15) can be substituted by one rotary three-way valve (18), cost can be reduced.

Further, the first solenoid valve (SV-1) and the second closing valve (1
No piping is necessary for providing 5), so that the piping length can be shortened. As a result, the pressure loss in the pipe can be reduced. In addition, the amount of refrigerant can be reduced. Further, the outdoor unit (20) can be made compact.

-Modifications- In each of the first and second embodiments, R410A, which is a refrigerant having a characteristic that the amount of change in latent heat due to a temperature change is large, is used as the refrigerant. However, the refrigerant used in the air conditioner (30) of the first embodiment or the air conditioner (31) of the second embodiment is not limited to R410A. Even with R22 conventionally used, the above effects can be obtained. That is, when the temperature is lower than the predetermined condensing temperature, the non-injection operation is performed, and when the temperature is higher than the predetermined condensing temperature, the injection operation is performed.

Further, the switching between the injection operation and the non-injection operation may not be based on a predetermined condensation temperature, but may be based on another reference amount, for example, a predetermined pressure.

The refrigeration apparatus according to the present invention is not limited to an air conditioner, but can be applied to a refrigeration apparatus or a refrigerator in a narrow sense. Also in this case, the above-described effects can be obtained.

[0064]

As described above, according to the present invention, the following effects are exhibited.

According to the first aspect of the present invention, either the injection operation or the non-injection operation can be arbitrarily performed by opening and closing the closing valve.

Therefore, for example, even if the condensing temperature rises and a sufficient enthalpy difference with respect to the refrigerant cannot be ensured in the non-injection operation, the required capacity is provided by performing the injection operation to increase the refrigerant circulation amount. Can be. On the other hand, when the condensing temperature is not so high, the non-injection operation enables efficient operation. As a result, by performing either the injection operation or the non-injection operation, an efficient operation according to the operation state can be performed.

According to the second or third aspect of the present invention, a closing valve for the bypass passage is not required. Further, by setting the first decompression mechanism and the bypass passage to be in communication with each other before installing the refrigeration apparatus, the closing valve on the downstream side of the use-side heat exchanger becomes unnecessary. Therefore, the two devices, the shutoff valve for the bypass passage and the shutoff valve on the downstream side of the use-side heat exchanger, can be replaced by one three-way valve, so that the cost can be reduced.

Further, since a pipe for providing the above-mentioned closing valve is not required, the length of the pipe can be shortened. As a result, the pressure loss in the pipe can be reduced. In addition, the amount of refrigerant can be reduced. Further, the size of the refrigeration system can be reduced.

According to the fourth aspect of the present invention, since the refrigerant has a characteristic in which the amount of change in the latent heat with respect to the temperature change is larger than the amount of change in R22, the injection operation or the non-injection operation is performed. The effect that any one of the driving can be arbitrarily selected and performed is more remarkably exhibited.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of an air-conditioning apparatus according to Embodiment 1.

FIG. 2 is a refrigerant circuit diagram of the air-conditioning apparatus according to Embodiment 2.

3A and 3B are diagrams illustrating the operation of a rotary type three-way valve, wherein FIG. 3A illustrates a setting state before non-injection operation, FIG. 3B illustrates a setting state before injection operation, and FIG. It is.

FIG. 4 is a refrigerant circuit diagram of a conventional air conditioner.

FIG. 5 is a diagram comparing R22 and R410A with respect to the amount of change in latent heat with respect to temperature change.

[Explanation of symbols]

 (1) Compressor (3) Indoor heat exchanger (4) First expansion valve (5) Second expansion valve (6) Gas-liquid separator (10) Bypass passage (11) Injection passage (14) First shut-off valve (15) Second shutoff valve (18) Rotary three-way valve (20) Outdoor unit (21) Indoor unit (SV-1) First solenoid valve (SV-2) Second solenoid valve

Claims (4)

[Claims] 1. A compressor (1), a use side heat exchanger (3), a first pressure reducing mechanism (4), a gas-liquid separator (6), and a second pressure reducing mechanism (5).
And a heat source side heat exchanger (7) in order, the gas-liquid separator (6)
And the compressor (1), a refrigerating apparatus provided with an injection passage (11) for injecting the gas refrigerant separated by the gas-liquid separator (6) into the compressor (1), Between the use side heat exchanger (3) and the second pressure reducing mechanism (5),
The bypass passage (10) having the on-off valve (SV-1) is the first pressure reducing mechanism
(4) A refrigeration apparatus provided in parallel with the gas-liquid separator (6). 2. A compressor (1), a use side heat exchanger (3), a first pressure reducing mechanism (4), a gas-liquid separator (6), and a second pressure reducing mechanism (5).
And a heat source side heat exchanger (7) in order, the gas-liquid separator (6)
And a compressor (1), wherein an injection passage (11) for injecting the gas refrigerant separated by the gas-liquid separator (6) into the compressor (1) is provided. (2) One end of a bypass passage (10) is connected between the pressure reducing mechanism (5) and the gas-liquid separator (6), and the other end of the bypass passage (10) is connected to a use side heat exchanger by a three-way valve (18). (3) and the first pressure reducing mechanism (4), the three-way valve (18) is connected to the use side heat exchanger (3) and the bypass passage.
(10), a state in which the use-side heat exchanger (3) communicates with the first pressure reducing mechanism (4), and a state in which the first pressure reducing mechanism (4) communicates with the bypass passage (10). A refrigeration apparatus characterized by being configured to be switchable to any one of the states. 3. The refrigeration system according to claim 2, wherein the three-way valve comprises a rotary three-way valve (18). 4. The refrigerant according to claim 1, wherein the refrigerant has a characteristic that a change amount of the latent heat with respect to the temperature change is larger than a change amount of the latent heat with respect to the temperature change of R22. A refrigeration apparatus characterized by using: