JPH1047799A - Freezing cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezing cycle device where a substitutive refrigerant can be used without touble. SOLUTION: This freezing cycle device has a freezing cycle 1 being made by connecting a compressor 2, a first heat exchanger 3, a pressure reducing devices 4 and 10, and a second heat exchanger 5 in order. A refrigerator where the saturation pressure at 50 deg.C is 2500kPa or more is used for the freezing cycle 1. The pressure reducing devices 4 and 10 have an expansion valve 4 and a capillary tube 10 provided in series to the expansion valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle apparatus, and more particularly to a refrigeration cycle apparatus having a saturation pressure at 50.degree.
The present invention relates to a refrigeration cycle device using a refrigerant having a pressure of Pa or more.

[0002]

2. Description of the Related Art In a conventional refrigeration cycle apparatus, an HCFC refrigerant or a CFC refrigerant is generally used, and in particular, an HCFC22 is frequently used. Although the HCFC 22 contains chlorine that causes ozone layer depletion, it also contains hydrogen, so that the ozone layer depletion coefficient is smaller than that of the CFC 12 that does not contain hydrogen. However, HCF
Although the ozone depletion coefficient of C22 is small but not zero, in order to protect the ozone layer, HFC or HC having an ozone depletion coefficient of zero is replaced with a refrigeration cycle device in place of the conventionally used HCFC22. Attempts have been made to use it as a refrigerant (alternative refrigerant). Research and development of equipment required for using such an alternative refrigerant are being conducted at a rapid pace.

[0003] Alternative refrigerants currently being studied include R32
(Difluoromethane) and R125 (pentafluoroethane) mixed refrigerant R410A, R32, R125 and R1
34a (tetrafluoroethane) mixed refrigerant R407C
And propane R290 (C ₃ H ₈ ). The characteristics of these alternative refrigerants are as follows when compared with R22 conventionally used. R410A: Operating pressure = about 150% Volume flow rate per unit capacity = about 70% (comparison in liquid state) R407C: Operating pressure = about 107% Volume flow rate per unit capacity = about 100% (however, liquid state) R290: Operating pressure = approximately 100% Volume flow rate per unit capacity = approximately 110% (however, comparison in a liquid state) R410A will be supplementarily described.
A is a mixed medium containing 50% of each of HFC32 and HFC125. Since the saturation pressure of both HFC32 and HFC125, which are component refrigerants of R410A, is higher than that of R22, the operating pressure of R410A is 1.5 times higher than the operating pressure of R22 as described above. Further, since the refrigeration capacity per volume flow rate of the HFC 32 is larger than that of R22, the volume flow rate per unit capacity is as small as 0.7 times R22 as described above.

[0004] As for R407C, its operating pressure is 1.07 times as high as that of R22.
As for R290, the volume flow per unit capacity is 1.1 times higher than R22.

According to the alternative refrigerant having the above characteristics, R2
The total flow rate of the refrigerant required to obtain the refrigerating capacity equivalent to 2 can be smaller than R22. For this reason, the pressure drop (pressure loss) due to the refrigerant flow inside the piping constituting the refrigeration cycle is reduced, and an advantageous feature that the system efficiency in the refrigeration cycle is improved is obtained.

However, since the conventional refrigeration cycle apparatus is designed on the premise that a conventional refrigerant such as R22 is used, an alternative refrigerant such as R410A is used as the design specification of the conventional refrigeration cycle apparatus as it is. The use causes various disadvantages.

For example, when an alternative refrigerant (R410 or the like) is used, the control range of the refrigerant flow rate to a low flow rate range becomes wider than when a conventional refrigerant (R22 or the like) is used. It is necessary to precisely control the flow rate of the refrigerant in a small area. For this reason, it is necessary to control the opening degree of the throttle valve of the refrigerant flow control device in a region very close to the valve closing point. When trying to control the degree of valve opening near the valve closing point in this way, a very small displacement of the needle near the valve opening of the throttle valve greatly affects the flow rate of the refrigerant. It will be difficult. As the refrigerant flow control device, a temperature type expansion valve, an electronic type expansion valve, a capillary tube and the like are used.

If the flow rate control is not performed properly and the operation is continued in a state where, for example, the flow rate of the refrigerant is larger than the proper amount, the compressor (compressor) is damaged / deteriorated by the liquid return, and the compressor is damaged. Service life (life) is shortened. Conversely, if the flow rate of the refrigerant becomes too small due to inappropriate flow control, the superheat in the evaporator (evaporator) becomes too large. If the superheat in the evaporator becomes excessive, the compressor will overheat and the temperature of the evaporator will fluctuate.Therefore, problems such as insufficient cooling capacity, reduced efficiency, condensation on equipment and dropping of dew water will occur. May occur.

Further, since the alternative refrigerant is a refrigerant (high-pressure refrigerant) used at a higher pressure than the conventional refrigerant, if the alternative refrigerant is used with the conventional refrigeration cycle apparatus as it is, the piping constituting the refrigeration cycle is not used. There is a possibility that the conventional pressure resistance performance such as that described above may be insufficient.

Therefore, in order to use the alternative refrigerant without any trouble, it is necessary to take the following improvement measures. (1) Withstand pressure performance of each component constituting the refrigeration cycle,
Increase strength. (2) The controllability of the refrigerant flow control device in the low flow rate range is improved.

The following can be considered as specific measures for implementing the above-mentioned improvement measures. (1) In order to increase the pressure resistance and strength of each component constituting the refrigeration cycle, the thickness of an outer portion, such as a refrigerant pipe, is increased, and the strength of internal components of the component device is improved. (2) In order to improve the controllability of the refrigerant flow control device in the low flow rate range, the diameter of the throttle portion of the refrigerant flow control device is reduced. Further, in the electronic expansion valve, the valve opening control is reduced.

[0012]

However, the above-mentioned improvement measures have the following problems. (1) Increasing the manufacturing cost by increasing the thickness of the refrigerant pipe or the like or strengthening the internal parts of the component devices, or increasing the weight of the control valve or the like to support the member. It is necessary to improve the strength, which causes a further increase in manufacturing cost. (2) Fine processing is required to reduce the diameter of the throttle portion of the refrigerant flow control device. However, this fine processing requires a very advanced processing technology, and the variation in processing accuracy becomes large. Therefore, the controllability of the refrigerant flow control device deteriorates. In addition, there is a problem that when the diameter of the aperture portion is reduced, foreign matter is likely to be clogged in the opening portion.

The following is a supplementary explanation of the problem (2). Assuming that the throttle section diameter cross-sectional area is S, the throttle section inlet pressure is P1, and the throttle section outlet pressure is P2, the refrigerant flow rate G is represented by the following equation.

[0014]

(Equation 1) As can be seen from the above relational expression, when the flow rate G of the refrigerant is constant, the larger the pressure difference P1-P2 between the inlet and the outlet of the throttle, the smaller the cross-sectional area S of the throttle. Here, the pressure difference P1-P when an alternative refrigerant is used
2 is larger than the conventional refrigerant, so that it is necessary to reduce the throttle section diameter cross-sectional area S as compared with the conventional case in order to appropriately control the refrigerant flow rate. However, in order to reduce the diameter of the throttle portion of the refrigerant flow control device, there is a limitation in machining as described above. For example, when a machining drill having a diameter of 1.5 mm or less is used, the machining drill itself has There is a problem in that the strength is insufficient, a large variation occurs in the processing accuracy, and the variation in the processing accuracy causes a variation in the flow characteristics of the refrigerant.

[0015] Therefore, there is a need for a measure for enabling the alternative refrigerant to be used without any trouble without taking the above-mentioned improvement measures.

Accordingly, an object of the present invention is to provide a refrigeration cycle apparatus which can solve the above various problems and can use an alternative refrigerant without any trouble.

[0017]

A refrigeration cycle apparatus according to the present invention has a refrigeration cycle formed by sequentially connecting a compressor, a first heat exchanger, a pressure reducing device, and a second heat exchanger. A refrigeration cycle apparatus in which a refrigerant having a saturation pressure at 50 ° C. of 2500 kPa or more is used for the refrigeration cycle, wherein the pressure reducing apparatus includes an expansion valve and a capillary provided in series with the expansion valve. And a tube. With such a configuration, it is possible to reduce the pressure difference in the expansion valve. For this reason,
Even when an alternative refrigerant having a higher operating pressure than the conventional refrigerant is used, the refrigerant can be controlled without any trouble under high reliability by using the expansion valve used in the conventional refrigeration cycle apparatus as it is. .

In the refrigeration cycle apparatus according to the present invention, the capillary tubes are disposed on both sides of the expansion valve. With such a configuration, in any case of the heating operation and the cooling operation, any one of the capillary tubes is located on the upstream side of the expansion valve. The refrigerant flowing into the valve has a two-phase flow, which makes it easier to control the pressure reduction in the expansion valve.

According to a third aspect of the present invention, in the refrigeration cycle apparatus, a bypass circuit for bypassing each of the capillary tubes is connected in parallel with each of the capillary tubes, and an inlet side of the expansion valve is provided in the middle of each of the bypass circuits. The check valves are respectively provided so as to face the directions of. With such a configuration, since the capillary tube located downstream of the expansion valve is bypassed by the bypass circuit, it is possible to prevent the decompression (throttle) of the refrigerant from becoming excessively large, and to prevent the refrigerant from being cooled. Control can be performed accurately.

In the refrigeration cycle apparatus according to the present invention, a two-way valve is provided in place of each of the check valves. In such a configuration, the refrigerant can be depressurized only on the upstream side of the expansion valve by opening and closing each two-way valve, so that the same effect as the third aspect of the invention can be obtained.

According to a fifth aspect of the present invention, there is provided a refrigeration cycle apparatus having a refrigeration cycle formed by sequentially connecting a compressor, a first heat exchanger, a pressure reducing device, and a second heat exchanger. Means that the saturation pressure at 50 ° C is 2500k
A refrigeration cycle device using a refrigerant having a pressure of Pa or more, wherein the pressure reducing device has an expansion valve and a capillary tube connected in parallel to the expansion valve, and the capillary tube is configured to perform the expansion. When the valve is fully closed, a refrigerant flow rate smaller than the minimum refrigerant flow rate of the expansion valve is formed. In such a configuration, since the capillary tube is connected in parallel with the expansion valve, the amount of throttle in the expansion valve can be smaller than when the pressure is reduced only by the expansion valve. In addition, since it is possible to control the refrigerant in a smaller flow rate region than in the conventional refrigeration cycle device, it is possible to accurately control the refrigerant even when an alternative refrigerant having a high operating pressure is used.

According to a sixth aspect of the present invention, in the refrigeration cycle apparatus, the expansion valve is an electronic expansion valve, and the opening torque of the electronic expansion valve is made larger than the closing torque. . With such a configuration, it is possible to reliably prevent a situation in which a once-closed expansion valve cannot be reopened.

A refrigeration cycle apparatus according to a seventh aspect of the present invention has a refrigeration cycle formed by sequentially connecting a compressor, a first heat exchanger, a decompression device, and a second heat exchanger. Means that the saturation pressure at 50 ° C is 2500k
A refrigeration cycle device in which a refrigerant having a pressure of Pa or more is used, and a short-circuit channel connecting two points having different pressures in the refrigeration cycle, and a refrigerant storage tank provided in the middle of the short-circuit channel, Each valve means provided on both sides of the refrigerant storage tank, opening and closing the valve means according to the operation state of the refrigeration cycle, a part of the refrigerant flowing in the refrigeration cycle to and from the refrigerant storage tank. And a valve control device for controlling the refrigerant flow rate. In such a configuration, since the flow rate of the refrigerant flowing in the refrigeration cycle can be controlled, even when an alternative refrigerant having a high operating pressure is used, damage to the compressor due to an excessive flow rate or insufficient cooling capacity due to an insufficient flow rate. In addition, it is possible to reliably prevent troubles such as condensation water falling.

The refrigeration cycle apparatus according to the present invention has a refrigeration cycle formed by sequentially connecting a compressor, a first heat exchanger, a pressure reducing device, and a second heat exchanger. Means that the saturation pressure at 50 ° C is 2500k
A refrigeration cycle device using a refrigerant having a pressure of Pa or more, wherein the pressure reducing device includes an electronic expansion valve having a valve seat, a cutout portion is formed in the valve seat, and the electronic expansion valve is fully closed. Then, a small amount of refrigerant flow is formed through the cutout portion. In such a configuration, it is possible to control the refrigerant flow rate to a very small flow rate by fully closing the expansion valve. Therefore, even when an alternative refrigerant having a high operating pressure is used, control of the refrigerant is performed. It can be performed accurately without any trouble.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Hereinafter, a first embodiment of a refrigeration cycle apparatus according to the present invention will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a refrigeration cycle of the refrigeration cycle apparatus according to the present embodiment, and the refrigeration cycle 1 is used for an air conditioner for cooling and heating capable of switching between a cooling operation and a heating operation.

The refrigerating cycle 1 includes a compressor 2, a four-way valve 6,
An outdoor heat exchanger 3, an electronic expansion valve 4, and an indoor heat exchanger 5 are provided, and these devices are sequentially connected via a refrigerant transport pipe 7 to form a closed circuit. In addition, an outdoor fan 8 is disposed beside the outdoor heat exchanger 3,
On the other hand, an indoor fan 9 is arranged beside the indoor heat exchanger 5.

In this embodiment, a capillary tube 10 is provided in series with the electronic expansion valve 4 in the middle of the refrigerant transport pipe 7 between the indoor heat exchanger 5 and the electronic expansion valve 4. ing. The capillary tube 10 has a function of reducing the pressure of the refrigerant in cooperation with the electronic expansion valve 4. For example, when an alternative refrigerant having an operating pressure of 1.5 times that of the conventional refrigerant is used, it becomes necessary. One-third of the pressure reduction amount (pressure difference) to be applied is set so as to be applied to the capillary tube 10, and the remaining two-thirds are set to be applied to the electronic expansion valve 4.

In the refrigerating cycle 1, the temperature is set to 50 ° C.
A refrigerant having a saturation pressure of 2500 kPa or more is used. Specifically, a refrigerant having a composition ratio of R32 of 40% or more, a refrigerant having a total composition ratio of R32 and R125 of 50% or more, and the like are given. In FIG. 1, the solid arrow line indicates the flow direction of the refrigerant during the cooling operation, and the dotted arrow line indicates the flow direction of the refrigerant during the heating operation.

Next, the operation of the refrigeration cycle apparatus according to the present embodiment will be described. During the cooling operation, a high-pressure liquid refrigerant that has radiated heat and liquefied in the outdoor heat exchanger 3 is supplied to the electronic expansion valve 4 from the port 4 a on the inlet side of the electronic expansion valve 4.
The pressure-reduced refrigerant flows into the electronic expansion valve 4
Flows out of the port 4b on the outlet side of. Exit port 4
b flows out from the inlet end 10a of the capillary tube 10 into the capillary tube 10 via the refrigerant transport pipe 7 and is further decompressed, and the depressurized refrigerant is discharged from the end of the capillary tube 10 on the outlet side. Part 1
0b.

The refrigerant depressurized in the electronic expansion valve 4 is further depressurized by the capillary tube 10 arranged in series downstream of the electronic expansion valve 4. Therefore, the pressure difference between the inlet side port 4a and the outlet side port 4b of the electronic expansion valve 4 is smaller than when the capillary tube 10 is not provided. As described above, when the operating pressure of the refrigerant in the refrigeration cycle 1 is 1.5 times that of the conventional refrigerant, the pressure difference P1 in the electronic expansion valve 4 and the pressure difference P1 in the capillary tube 10
If the ratio to P2 is P1: P2 = 2: 1, the pressure difference in the electronic expansion valve 4 becomes equal to the pressure difference when a conventional refrigerant is used.

On the other hand, during the heating operation, the indoor heat exchanger 5
The high-pressure liquid refrigerant that has been radiated and liquefied in the above flows into the capillary tube 10 from the inlet end 10b of the capillary tube 10 and is decompressed, and the depressurized refrigerant flows out from the outlet end 10a of the capillary tube 10. I do. The refrigerant flowing out from the outlet end 10a flows into the electronic expansion valve 4 from the inlet side port 4b of the electronic expansion valve 4 via the refrigerant transport pipe 7, and is further reduced in pressure. It flows out of the port 4a on the outlet side of the electronic expansion valve 4.

The refrigerant depressurized in the capillary tube 10 is further depressurized by the electronic expansion valve 4 arranged on the downstream side of the capillary tube 10. For this reason, the pressure difference between the port 4a on the inlet side and the port 4b on the outlet side of the electronic expansion valve 4 is smaller than in the case where the capillary tube 10 is not provided, as in the case of the cooling operation.

In the heating operation, since the capillary tube 10 is located upstream of the electronic expansion valve 4, the refrigerant flowing into the electronic expansion valve 4 is depressurized by the capillary tube 10. It is a formed two-phase flow in which a liquid phase and a gas phase are mixed. Here, when the refrigerant in the two-phase state is decompressed, the same amount of decompression can be achieved by gentler throttling than in the case where the refrigerant in the liquid phase is depressurized. Therefore, by arranging the capillary tube 10 on the upstream side of the electronic expansion valve 4, it is sufficient to use a gentle throttle in the electronic expansion valve 4.

As described above, according to this embodiment, the capillary tube 10 is connected in series with the electronic expansion valve 4.
Is provided, the pressure difference in the electronic expansion valve 4 can be reduced. For this reason, even when an alternative refrigerant having a higher operating pressure than the conventional refrigerant is used, the electronic expansion valve 4 used in the conventional refrigeration cycle apparatus can be used as it is without any trouble under high reliability. Can be controlled.

According to the present embodiment, in the heating operation, since the capillary tube 10 is located on the upstream side of the electronic expansion valve 4, the refrigerant flowing into the electronic expansion valve 4 has two phases. Therefore, the pressure reduction control in the electronic expansion valve 4 is further facilitated.

In this embodiment, a capillary tube 10 is provided between the indoor heat exchanger 5 and the electronic expansion valve 4.
However, the capillary tube 10 may be disposed between the outdoor heat exchanger 3 and the electronic expansion valve 4.

Although the electronic expansion valve 4 is used as the expansion valve in the present embodiment and the later-described embodiments, a temperature expansion valve may be used instead of the electronic expansion valve 4.

Furthermore, in the present embodiment and the embodiments described later, an air conditioner is described as an example, but the scope of the present invention is not limited to an air conditioner, but can be applied to a refrigeration system and the like. Needless to say.

Second Embodiment Next, a refrigeration cycle apparatus according to a second embodiment of the present invention will be described with reference to FIG. In this embodiment, a part of the configuration of the first embodiment is changed. In the following description, the same members as those of the first embodiment are denoted by the same reference numerals, and detailed description is omitted. .

In FIG. 2, reference numeral 20 indicates a refrigeration cycle of the refrigeration cycle apparatus according to the present embodiment, and this refrigeration cycle 20 is connected to the indoor heat exchanger 5 and the electronic expansion valve 4 in the same manner as in the first embodiment. A first capillary tube 21 is provided between them. The refrigeration cycle 20 includes, in addition to the first capillary tube 21, the outdoor heat exchanger 3.
A second capillary tube 22 is provided between the second expansion tube 4 and the electronic expansion valve 4. That is, the first capillary tube 21, the electronic expansion valve 4, and the second capillary tube 22 are sequentially connected in series via the refrigerant transport pipe 7. In the refrigeration cycle 20, a refrigerant having a saturation pressure at 50 ° C. of 2500 kPa or more is used as in the refrigeration cycle 1 of the first embodiment.

Next, the operation of the refrigeration cycle apparatus according to the present embodiment will be described. During the cooling operation, the high-pressure liquid refrigerant radiated and liquefied in the outdoor heat exchanger 3 flows into the second capillary tube 22 from the inlet end 22a of the second capillary tube 22, and is decompressed. The cooled refrigerant flows out from the end 22b on the outlet side of the second capillary tube 22. The refrigerant flowing out from the outlet end 22b flows into the electronic expansion valve 4 from the inlet side port 4a of the electronic expansion valve 4 via the refrigerant transport pipe 7, and is further decompressed. It flows out of the port 4b on the outlet side of the electronic expansion valve 4. The refrigerant flowing out of the outlet port 4b flows into the first capillary tube 21 from the inlet end 21a of the first capillary tube 21 via the refrigerant transport pipe 7, and after being further depressurized, the first capillary tube Exit end 21b of 21
Spill out of.

On the other hand, during the heating operation, the indoor heat exchanger 5
The high-pressure liquid refrigerant that has radiated and liquefied in the first capillary tube 21 flows into the first capillary tube 21 from the end 21b on the inlet side of the first capillary tube 21 and is decompressed, and the decompressed refrigerant is on the exit side of the first capillary tube 21 Flows out from the end 21a. The refrigerant flowing out from the outlet end 21a flows into the electronic expansion valve 4 from the inlet port 4b of the electronic expansion valve 4 via the refrigerant transport pipe 7, and is further decompressed. It flows out of the port 4a on the outlet side of the electronic expansion valve 4. The refrigerant flowing out of the outlet port 4a flows into the second capillary tube 22 from the inlet end 22b of the second capillary tube 22 via the refrigerant transport pipe 7, and after being further depressurized, the second refrigerant flows into the second capillary tube 22.
It flows out from the end 22a on the outlet side of the capillary tube 22.

As described above, in the present embodiment, the refrigerant flowing through the refrigeration cycle 20 is first used in either the heating operation (dotted line in the figure) or the cooling operation (solid line in the figure). First, the pressure is reduced by the first or second capillary tubes 21 and 22, and then further reduced by the electronic expansion valve 4. The refrigerant decompressed by the first or second capillary tubes 21 and 22 and the electronic expansion valve 4 is supplied to the second or first capillary tube 22 located downstream of the electronic expansion valve 4.
The pressure is further reduced by 21.

As described above, according to the present embodiment, since the first and second capillary tubes 21 and 22 are provided in series with the electronic expansion valve 4, the pressure difference in the electronic expansion valve 4 is reduced. It is possible to make it smaller. For this reason, even when an alternative refrigerant having a higher operating pressure than the conventional refrigerant is used, the electronic expansion valve 4 used in the conventional refrigeration cycle apparatus can be used as it is without any trouble under high reliability. Can be controlled.

Further, according to the present embodiment, the first or second capillary tube 21, 2 is located upstream of the electronic expansion valve 4 in both the heating operation and the cooling operation.
2 is located, the refrigerant flowing into the electronic expansion valve 4 becomes a two-phase flow regardless of whether the heating operation or the cooling operation is performed, and therefore, the pressure reduction control in the electronic expansion valve 4 is further performed. It will be easy.

Third Embodiment Next, a refrigeration cycle apparatus according to a third embodiment of the present invention will be described with reference to FIG. In this embodiment, a part of the configuration of the second embodiment is changed. In the following description, the same members as those of the second embodiment are denoted by the same reference numerals, and detailed description is omitted. .

In FIG. 3, reference numeral 30 denotes a refrigeration cycle of the refrigeration cycle apparatus according to the present embodiment. This refrigeration cycle 30 includes first and second refrigeration cycles on both sides of the electronic expansion valve 4 as in the second embodiment. Capillary tube 21,
22. In addition, in the refrigeration cycle 30, like the refrigeration cycle 1 of the first embodiment, 50
A refrigerant having a saturation pressure at 2500C of 2500 kPa or more is used.

In this embodiment, the first and second bypass pipes 31 and 32 for bypassing the first and second capillary tubes 21 and 22 are connected to the first and second capillary tubes 21 and 22. Each is connected in parallel. In the middle of the first and second bypass pipes 31 and 32, the first and second check valves 3 are provided.
3 and 34 are provided respectively, and these first and second check valves 33 and 34 are connected to their respective inlet ports 33.
a, 34 a are arranged so as to face the direction of the electronic expansion valve 4.

Next, the operation of the refrigeration cycle apparatus according to the present embodiment will be described. In the cooling operation, the high-pressure liquid refrigerant radiated and radiated in the outdoor heat exchanger 3 is connected to the inlet side end 32a of the second bypass pipe 32 via the refrigerant transport pipe 7. To reach. Here, since the inlet port 34a of the second check valve 34 provided in the middle of the second bypass pipe 32 faces the direction of the electronic expansion valve 4, the refrigerant is shut off by the second check valve 34. Therefore, it does not flow into the second bypass pipe 32. Therefore, all the refrigerant flows into the second capillary tube 22 to be decompressed, and then flows into the electronic expansion valve 4 via the refrigerant transport pipe 7.

The refrigerant flowing into the electronic expansion valve 4 is further decompressed, and the decompressed refrigerant is passed through the refrigerant transport pipe 7 to the portion where the inlet end 31a of the first bypass pipe 31 is connected. To reach. Here, the first bypass pipe 31
The first check valve 33 provided in the middle of the inlet port 3
Since 3 a faces the direction of the electronic expansion valve 4, the refrigerant flows through the first bypass pipe 31 without being shut off by the first check valve 33, and from the end 31 b on the outlet side of the first bypass pipe 31. leak. Therefore, decompression in the first capillary tube 21 is not performed.

On the other hand, during the heating operation, the indoor heat exchanger 5
The high-pressure liquid refrigerant that has been radiated and liquefied at the point (a) reaches the location where the end 31b on the inlet side of the first bypass pipe 31 is connected via the refrigerant transport pipe 7. Here, the first
Since the inlet port 33a of the first check valve 33 provided in the middle of the bypass pipe 31 faces the direction of the electronic expansion valve 4, the refrigerant is shut off by the first check valve 33 and the first bypass pipe 33 is opened. It does not flow into 31. Therefore, all the refrigerant flows into the first capillary tube 21 to be decompressed, and then flows into the electronic expansion valve 4 via the refrigerant transport pipe 7.

The refrigerant flowing into the electronic expansion valve 4 is further decompressed, and the depressurized refrigerant passes through the refrigerant transport pipe 7 to a portion where the end 32a on the inlet side of the second bypass pipe 32 is connected. To reach. Here, the second bypass pipe 32
The second check valve 34 provided in the middle of the inlet port 3
Since 4a faces the direction of the electronic expansion valve 4, the refrigerant flows through the second bypass pipe 32 without being shut off by the second check valve 34, and from the end 32b on the outlet side of the second bypass pipe 32. leak. Therefore, the pressure in the second capillary tube 22 is not reduced.

As described above, in the present embodiment, the refrigerant flowing through the refrigeration cycle 30 is first used in either the heating operation (dotted line in the drawing) or the cooling operation (solid line in the drawing). First, the pressure is reduced by the first or second capillary tubes 21 and 22, and then further reduced by the electronic expansion valve 4. The refrigerant decompressed by the first or second capillary tubes 21 and 22 and the electronic expansion valve 4 is located downstream of the electronic expansion valve 4 via the second or first bypass pipes 22 and 21. Therefore, the pressure is not reduced on the downstream side of the electronic expansion valve 4, because the gas flows by bypassing the second or first capillary tube 22, 21.

As described above, according to the present embodiment, the first and second capillary tubes 21 and 22 are provided in series with the electronic expansion valve 4 in the same manner as in the second embodiment. The pressure difference in the electronic expansion valve 4 can be reduced. For this reason, even when an alternative refrigerant having a higher operating pressure than the conventional refrigerant is used, the electronic expansion valve 4 used in the conventional refrigeration cycle apparatus can be used as it is without any trouble under high reliability. Can be controlled.

According to this embodiment, as in the second embodiment, in either case of the heating operation or the cooling operation, the first or the second valve is provided upstream of the electronic expansion valve 4. Since one of the capillary tubes 21 and 22 is located, the refrigerant flowing into the electronic expansion valve 4 has a two-phase flow regardless of whether the operation is heating or cooling.
The pressure reduction control in the electronic expansion valve 4 is further facilitated.

In addition to the above features, according to the present embodiment, the first or second capillary tube 21, 22 located downstream of the electronic expansion valve 4 is connected to the first or second bypass pipe 31. , 32, it is possible to prevent the pressure reduction (throttle) of the refrigerant from becoming excessively large, and to control the refrigerant accurately.

Modification Next, a modification of the third embodiment will be described with reference to FIG. In the refrigeration cycle 40 according to this modification, first and second two-way valves 41 and 42 are provided instead of the first and second check valves 33 and 34.

In this modification, during the cooling operation, the first two-way valve 41 located downstream of the electronic expansion valve 4 is opened and the first two-way valve 41 located upstream of the electronic expansion valve 4 is opened. The second two-way valve 42 is closed. Then, the refrigerant from the outdoor heat exchanger 3 flows into the electronic expansion valve 4 after being depressurized by the second capillary tube 22, and is further depressurized by the electronic expansion valve 4, and then passes through the first bypass pipe 31. Flow through the first capillary tube 21. On the other hand, during the heating operation, the first two-way valve 41
Is closed and the second two-way valve 42 is opened to reduce the pressure of the refrigerant only on the upstream side of the electronic expansion valve 4 as in the case of the cooling operation.

As described above, in this modification, the refrigerant can be depressurized only on the upstream side of the electronic expansion valve 4 by opening and closing the first two-way valve 41 and the second two-way valve. Therefore, the same effect as in the third embodiment can be obtained.

Fourth Embodiment Next, a refrigeration cycle apparatus according to a fourth embodiment of the present invention will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 5, reference numeral 50 denotes a refrigeration cycle of the refrigeration cycle apparatus according to the present embodiment. The refrigeration cycle 50 includes the electronic expansion valve 4 as in each of the above-described embodiments. In the refrigeration cycle 50, a refrigerant having a saturation pressure at 50 ° C. of 2500 kPa or more is used.

In this embodiment, a capillary tube 52 is connected in parallel to the electronic expansion valve 4 via a bypass pipe 51. The capillary tube 52 is configured to form a refrigerant flow rate smaller than the minimum refrigerant flow rate of the electronic expansion valve 4 when the electronic expansion valve 4 is fully closed.

Next, the operation of the refrigeration cycle apparatus according to the present embodiment will be described. In both the cooling operation (solid arrow in the drawing) and the heating operation (dotted arrow in the drawing), the refrigerant is supplied to the electronic expansion valve 4 in parallel with the electronic expansion valve 4. Capillary tube 52 connected to
And decompressed by both. Therefore, the throttle amount in the electronic expansion valve 4 is smaller than when the pressure is reduced only by the electronic expansion valve 4.

In this embodiment, by fully closing the electronic expansion valve 4, it is possible to secure a refrigerant flow rate smaller than the minimum refrigerant flow rate of the electronic expansion valve 4. Therefore, it is possible to control the refrigerant in a smaller flow rate region than in the conventional refrigeration cycle device.

As described above, according to the present embodiment, the capillary tube 52 is provided in parallel with the electronic expansion valve 4.
Is connected, the throttle amount in the electronic expansion valve 4 can be smaller than in the case where the pressure is reduced only by the electronic expansion valve 4.
For this reason, even when an alternative refrigerant having a higher operating pressure than the conventional refrigerant is used, the electronic expansion valve 4 used in the conventional refrigeration cycle apparatus can be used as it is without any trouble under high reliability. Can be controlled.

Further, according to the present embodiment, it is possible to control the refrigerant in a smaller flow rate region as compared with the conventional refrigeration cycle apparatus, so that the refrigerant can be controlled even when an alternative refrigerant having a high operating pressure is used. Can be performed accurately.

Modification 1 Next, a modification of the fourth embodiment will be described with reference to FIG. Refrigeration cycle device 9 in this modification example
0, the first and second sides of the parallel connection circuit of the capillary tube 52 and the electronic expansion valve 4 (front and rear).
Are provided.

In this modification, the refrigerant is supplied to one of the capillary tubes 21 or 22 in either the heating operation (dotted line in the drawing) or the cooling operation (solid line in the drawing).
(21 during heating and 22 during cooling), the pressure is reduced by both the electronic expansion valve 4 and the capillary tube 52, and further reduced by the capillary tube 22 or 21.

Therefore, in this modification, the length of the capillary tube 52 connected in parallel to the electronic expansion valve 4 can be reduced as compared with the fourth embodiment shown in FIG. Further, similarly to the fourth embodiment, the throttle amount in the electronic expansion valve 4 is smaller than when the pressure is reduced only by the electronic expansion valve 4. Further, the pressure resistance of the electronic expansion valve 4 can be reduced.

Second Modification Next, another modification of the fourth embodiment will be described. This modification is a modification of the electronic expansion valve 4 according to the above embodiment.
, And is characterized in that the torque in the opening direction of the electronic expansion valve 4 is larger than the torque in the closing direction. The following is a method of increasing the torque in the opening direction, and in this modification, any one of the following methods or a combination of the methods is applied. (1) The voltage applied to the electronic expansion valve 4 is set high. (2) Change the 1-2-phase excitation to the 2-phase excitation. (3) The drive frequency (pps) of the electronic expansion valve 4 is set low.

As described above, according to the present modification, the torque in the opening direction is made larger than the torque in the closing direction. Therefore, it is possible to reliably prevent the once-closed electronic expansion valve 4 from being unable to reopen. be able to.

Fifth Embodiment Next, a refrigeration cycle apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, a part of the configuration of the second embodiment is changed. In the following description, the same members as those of the second embodiment are denoted by the same reference numerals, and detailed description is omitted. .

In FIG. 6, reference numeral 60 denotes a refrigeration cycle of the refrigeration cycle apparatus according to the present embodiment, and the refrigeration cycle 60 is the same as that of the second embodiment.
First and second capillary tubes 21 and 2 on both sides of
2 is provided. In the refrigeration cycle 60,
As in the case of the refrigeration cycle 20 of the second embodiment, at 50 ° C.
A refrigerant having a saturation pressure of 2500 kPa or more is used.

The refrigeration cycle 60 is connected to the short-circuit pipe 61.
And one end 61 a of the short-circuit pipe 61.
Is connected to the refrigerant transport pipe 7 between the first capillary tube 21 and the electronic expansion valve 4, and is connected to the short-circuit pipe 61.
Is connected to the refrigerant transport pipe 7 on the suction side of the compressor 2. Here, in both the cooling operation and the heating operation, there is a pressure difference between one end 61a of the short-circuit pipe 61 and the other end 61b.

In the middle of the short-circuit pipe 61, the refrigerant storage tank 6
2 are provided, and on both sides of the refrigerant storage tank 62, on-off valves 63 and 64 are provided, respectively. In addition, a signal line 6 is connected to each of the on-off valves 63 and 64.
A valve control device 67 is connected via 5 and 66. The valve control device 67 controls the operation frequency of the compressor 2, the opening amount of the electronic expansion valve 4, the amount of superheat, the degree of supercooling, the temperature of the compressor 2, the temperature of the discharged refrigerant, the pressure in the refrigeration cycle, and the like. Opening / closing valves 63, 64 based on detection data on the situation
For controlling the opening and closing of.

Next, the operation of the refrigeration cycle apparatus according to the present embodiment will be described. The valve control device 67 determines whether or not the flow rate of the refrigerant flowing in the refrigerant transport pipe 7 is excessive based on the detection data regarding the operation status.
When it is determined that the flow rate of the refrigerant is excessive, the on-off valves 63 and 64 are controlled to open and close via signal lines 65 and 66, and a part of the refrigerant flowing in the refrigerant transport pipe 7 is transferred to the refrigerant storage tank. It is taken into 62 and stored. On the other hand, when the flow rate of the refrigerant flowing in the refrigerant transport pipe 7 becomes excessively small, the valve control device 67 controls the on-off valves 63 and 64 again to transfer the refrigerant in the refrigerant storage tank 62 into the refrigerant transport pipe 7. Reflux.

Further, when an abnormality occurs such that the actual pressure exceeds the set pressure based on the signal of the pressure switch or the pressure sensor, the refrigerant in the refrigeration cycle 60 is taken into the refrigerant storage tank 62 to reduce the actual pressure. And increase the safety and life of the equipment.

As described above, according to the present embodiment, since the flow rate of the refrigerant flowing in the refrigerant transport pipe 7 can be controlled, even when an alternative refrigerant having a high operating pressure is used, the compression due to the excessive flow rate can be performed. Failures such as damage to the machine 2, insufficient cooling capacity due to an insufficient flow rate, and dropping of dew condensation water can be reliably prevented.

Next, a modification of the fifth embodiment will be described with reference to FIG. In the refrigeration cycle 70 of this modification, one end 61a of the short-circuit pipe 61 is connected to the refrigerant transport pipe 7 between the outdoor heat exchanger 3 and the second capillary tube 22, and the other end of the short-circuit pipe 61 End 6
1b is the indoor heat exchanger 5 and the first capillary tube 21
Is connected to a refrigerant transport pipe 7 between the two. And also in the case of this modification, similarly to the case of the above-mentioned fifth embodiment, in any of the cooling operation and the heating operation, between the one end 61a and the other end 61b of the short-circuit pipe 61. Has a pressure difference.

Also in this modified example having such a configuration, the refrigerant flowing through the refrigerant transport pipe 7 is opened and closed by operating the on-off valves 63 and 64 by the valve control device 67 in the same manner as in the above embodiment. Therefore, even when an alternative refrigerant having a high operating pressure is used, the refrigerant can be appropriately controlled without any trouble.

Sixth Embodiment Next, a refrigeration cycle apparatus according to a sixth embodiment of the present invention will be described with reference to FIGS. The same members as those in the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

FIG. 8 shows a refrigeration cycle according to this embodiment. This refrigeration cycle 80 has an electronic expansion valve 81. FIG. 9 is a vertical cross-sectional view showing the entirety of the electronic expansion valve 81. In FIG. FIG. 10 is an enlarged vertical sectional view of the narrowed portion A, and FIG. 11 is a horizontal sectional view taken along the line 11-11 in FIG.

As shown in FIGS. 10 and 11, the throttle portion A has a valve stem 82 and a valve seat 83 into which the tip end portion 82a of the valve stem is inserted. Further, in the present embodiment, cutout portions 84, 84 are formed in the upper end portion 83a of the valve seat 83.

In the present embodiment having such a configuration, when the electronic expansion valve 81 is fully closed, a minute flow rate is formed through the notches 84 formed in the upper end 83a of the valve seat 83. The refrigerant circulates. Therefore, by fully closing the electronic expansion valve 81, the flow rate of the refrigerant flowing through the refrigeration cycle 80 can be controlled to a very small flow rate.

As described above, according to this embodiment, the notches 84, 84 are formed in the upper end portion 83a of the valve seat 83 of the electronic expansion valve 81, so that the electronic expansion valve 81 can be fully closed. Thus, the flow rate of the refrigerant can be controlled to a very small flow rate. Therefore, even when an alternative refrigerant having a high operating pressure is used, the refrigerant can be accurately controlled without any trouble.

[0086]

As described above, in the refrigeration cycle apparatus according to the present invention, since the controllability of the refrigerant in the minute flow rate range is extremely high, the saturation pressure at 50 ° C. is 2500 kPa.
The above-described alternative refrigerant can be accurately controlled without any trouble, and a good operation can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing a refrigeration cycle of a first embodiment of a refrigeration cycle device according to the present invention.

FIG. 2 is a schematic system diagram showing a refrigeration cycle of a refrigeration cycle apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic system diagram showing a refrigeration cycle of a refrigeration cycle apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic system diagram showing a refrigeration cycle of a modification of the third embodiment of the refrigeration cycle apparatus according to the present invention.

FIG. 5 is a schematic system diagram showing a refrigeration cycle of a refrigeration cycle apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a schematic system diagram showing a refrigeration cycle of a refrigeration cycle apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a schematic system diagram showing a refrigeration cycle of a modification of the refrigeration cycle apparatus according to the fifth embodiment of the present invention.

FIG. 8 is a schematic system diagram showing a refrigeration cycle of a refrigeration cycle apparatus according to a sixth embodiment of the present invention.

FIG. 9 is a longitudinal sectional view showing an electronic expansion valve of a refrigeration cycle apparatus according to a sixth embodiment of the present invention.

FIG. 10 is an enlarged vertical sectional view showing a main part of an electronic expansion valve of a refrigeration cycle apparatus according to a sixth embodiment of the present invention.

FIG. 11 is a perspective view of an essential part of the electronic expansion valve shown in FIG.
FIG. 11 is an enlarged cross-sectional view taken along section line 11;

FIG. 12 is a schematic system diagram showing a refrigeration cycle of Modification 1 of the fourth embodiment of the refrigeration cycle device according to the present invention.

[Explanation of symbols]

1, 20, 30, 40, 50, 60, 70, 80 Refrigeration cycle 2 Compressor 3 Outdoor heat exchanger 4, 81 Electronic expansion valve 5 Indoor heat exchanger 6 Four-way valve 7 Refrigerant transport piping 8 Outdoor fan 9 Indoor fan 10, 52 Capillary tube 21 First capillary tube 22 Second capillary tube 31 First bypass pipe 32 Second bypass pipe 33 First check valve 33a Inlet port of first check valve 34 Second check valve 34a Second reverse Inlet port of stop valve 41 First two-way valve 42 Second two-way valve 51 Bypass pipe 61 Short-circuit pipe 61a, 61b End of short-circuit pipe 62 Refrigerant storage tank 63, 64 Open / close valve 65, 66 Signal line 67 Valve control device 82 Valve stem of electronic expansion valve 83 Valve seat of electronic expansion valve 83a Upper end of valve seat 84 Notch

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F25B 41/06 F25B 41/06 N

Claims (8)

[Claims] 1. A compressor, a first heat exchanger, a pressure reducing device, and a second
A refrigeration cycle formed by sequentially connecting heat exchangers, wherein the refrigeration cycle has a saturation pressure at 50 ° C. of 2;
A refrigeration cycle device using a refrigerant having a pressure of 500 kPa or more, wherein the pressure reducing device includes an expansion valve and a capillary tube provided in series with the expansion valve. 2. The refrigeration cycle apparatus according to claim 1, wherein said capillary tubes are provided on both sides of said expansion valve. 3. A non-return valve, wherein a bypass circuit for bypassing each of the capillary tubes is connected in parallel to each of the capillary tubes, and an inlet side is directed toward the expansion valve in the middle of each of the bypass circuits. The refrigeration cycle apparatus according to claim 2, wherein 4. The refrigeration cycle apparatus according to claim 3, wherein two-way valves are provided in place of the check valves. 5. A compressor, a first heat exchanger, a pressure reducing device and a second heat exchanger.
A refrigeration cycle formed by sequentially connecting heat exchangers, wherein the refrigeration cycle has a saturation pressure at 50 ° C. of 2;
A refrigeration cycle device using a refrigerant having a pressure of 500 kPa or more, wherein the pressure reducing device has an expansion valve and a capillary tube connected in parallel to the expansion valve, and the capillary tube has a function of the expansion tube. A refrigeration cycle apparatus characterized in that when the valve is fully closed, a refrigerant flow rate smaller than the minimum refrigerant flow rate of the expansion valve is formed. 6. The refrigeration cycle apparatus according to claim 5, wherein the expansion valve is an electronic expansion valve, and the torque in the opening direction of the electronic expansion valve is larger than the torque in the closing direction. 7. A compressor, a first heat exchanger, a pressure reducing device and a second heat exchanger.
A refrigeration cycle formed by sequentially connecting heat exchangers, wherein the refrigeration cycle has a saturation pressure at 50 ° C. of 2;
A refrigeration cycle apparatus using a refrigerant having a pressure of 500 kPa or more, a short-circuit channel connecting two points having different pressures in the refrigeration cycle, and a refrigerant storage tank provided in the middle of the short-circuit channel, Each valve means provided on both sides of the refrigerant storage tank, opening and closing the valve means according to the operation state of the refrigeration cycle, a part of the refrigerant flowing through the refrigeration cycle to and from the refrigerant storage tank. A refrigeration cycle device comprising: 8. A compressor, a first heat exchanger, a pressure reducing device, and a second heat exchanger.
A refrigeration cycle formed by sequentially connecting heat exchangers, wherein the refrigeration cycle has a saturation pressure at 50 ° C. of 2;
A refrigeration cycle device using a refrigerant having a pressure of 500 kPa or more, wherein the pressure reducing device includes an electronic expansion valve having a valve seat, a cutout portion is formed in the valve seat, and the electronic expansion valve is fully closed. A refrigeration cycle device wherein a small amount of refrigerant flow is formed through the cutout portion when the refrigeration cycle is performed.