JPH10238902A - Refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a refrigerating cycle for maintaining desired ability without increasing a channel resistance of an expansion mechanism such as a capillary tube even if sludge is generated. SOLUTION: The refrigerating cycle comprises a compressor, a four-way valve, a condenser, an expansion mechanism and an evaporator. In this case, HFC refrigerant containing no chlorine and lubricating oil made of ester having compatibility with the refrigerant are sealed in the cycle. An inner surface of a capillary tube 4 for constituting the mechanism is formed of a uneven surface 6 made of steps of the recesses and convexities of 10 to 25μm. Thus, even if sludge 7 is generated when the refrigerant and oil are used and adhered to the surface 6 of the tube 4, roughness of the inner surface is not largely changed. Therefore, channel resistance of the inner surface of the tube 4 is not increased to prevent occurrence of a fault due to a decrease in a flow rate of the refrigerant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle such as an air conditioner in which an HFC-based refrigerant and an ester oil or an ether oil are sealed.

[0002]

2. Description of the Related Art FIG.
FIG. 2 is a refrigerant circuit diagram showing a conventional refrigeration cycle similar to the refrigeration cycle disclosed in Japanese Patent Application Laid-Open Publication No. H10-15064. In the figure, 1 is a compressor, 2 is a four-way valve, 3 is an indoor heat exchanger, 4 is a capillary tube, and 5 is an outdoor heat exchanger.

[0003] The conventional refrigeration cycle is configured as described above. For example, during a cooling operation, a high-temperature and high-pressure gas refrigerant is discharged from the compressor 1 and enters the outdoor heat exchanger 5 through the four-way valve 2. Then, in the outdoor heat exchanger 5, the refrigerant exchanges heat with the outdoor air, condenses and becomes a refrigerant liquid, and enters the capillary tube 4.

[0004] Then, the refrigerant is decompressed in the capillary tube 4, becomes a two-phase refrigerant, and enters the indoor heat exchanger 3. Further, in the indoor heat exchanger 3, the refrigerant exchanges heat with the indoor air, evaporates and becomes a gas refrigerant, and returns to the compressor 1 again through the four-way valve 2.

[0005]

In the above-described conventional refrigeration cycle, when an HFC-based refrigerant containing no chlorine and an ester oil or an ether oil having compatibility with the HFC-based refrigerant are used, a conventional refrigeration cycle is generally used. Unlike a widely used HCFC-based refrigerant, the lubricating action of chlorine cannot be expected, and sludge is likely to be generated due to the high hygroscopicity and hydrolytic properties of ester oil or ether oil.

[0006] The generated sludge adheres to the inner surface of the capillary tube 4, and when an acceleration test for several thousand hours corresponding to the life cycle period of an air conditioner or the like is performed, the inner surface roughness of the capillary tube 4 is reduced. 10 μm ~
Increase by 25 μm. As a result, there has been a problem in that the flow path resistance increases, and the heat exchange capacity decreases due to a decrease in the refrigerant flow rate, discharge pressure increases, and discharge temperature increases.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a first object of the invention is to provide a refrigeration cycle in which the flow path resistance of an expansion mechanism such as a capillary tube does not increase even if sludge is generated. And It is a second object of the present invention to obtain a refrigeration cycle in which a capillary tube to which sludge has adhered can be easily replaced.

[0008]

According to the present invention, there is provided a refrigeration cycle comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly composed of an ester or ether compatible with the refrigerant is enclosed.
Then, the inner surface of the capillary tube constituting the expansion mechanism is formed by a concave-convex surface having a step of a concave portion and a convex portion of 10 μm to 25 μm.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of an HFC-based refrigerant containing no chlorine and comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, A lubricating oil containing a soluble ester or ether as a main component is sealed therein, and the expansion mechanism is constituted by a polytetrafluoroethylene tube.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of an HFC-based refrigerant containing no chlorine and comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, A lubricating oil containing a soluble ester or ether as a main component is sealed therein, and the expansion mechanism is provided with a spiral groove on the pipe and the peripheral surface. It is constituted by a polytetrafluoroethylene rod forming a path.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of a chlorine-free HFC-based refrigerant and composed of a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, A lubricating oil containing a soluble ester or ether as a main component is sealed therein, and a capillary tube which constitutes an expansion mechanism and has an uneven surface on an inner surface of a large diameter portion formed on an inlet side is provided.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of a chlorine-free HFC-based refrigerant, which is constituted by a compressor, a four-way valve, a condenser, an expansion mechanism and an evaporator, A lubricating oil containing a soluble ester or ether as a main component is sealed therein, and both a first capillary tube and a second capillary tube constituting an expansion mechanism and a switching valve arranged corresponding to at least one of these two tubes are provided. Provided.

Further, in the refrigeration cycle according to the present invention, a large step uneven surface having a large step between the concave portion and the convex portion is formed on one inner surface of both the first capillary tube and the second capillary tube. At the beginning of the operation, a flow path passing through the large uneven surface is formed.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of an HFC-based refrigerant containing no chlorine and comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, A lubricating oil containing a soluble ester or ether as a main component is sealed therein, and shutoff valves are provided at connection portions at both ends of a capillary tube constituting an expansion mechanism.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows an example of an embodiment of the present invention, and is a cross-sectional view along a length of a capillary tube. The refrigeration cycle is configured in the same manner as in FIG. 6 except for FIG. In the figure, reference numeral 6 denotes an uneven surface formed on the inner surface of the capillary tube 4, in which concave portions and convex portions are arranged at substantially equal intervals in a direction along the inner surface of the capillary tube 4, and a step between the concave portion and the convex portion is 10 μm to 25 μm. Is formed.

In FIG. 1A, the inner surface of the capillary tube 4, that is, the concave portion of the uneven surface 6 is formed in a semicircular cross section, and in FIG. 1B, the convex portion of the uneven surface 6 is formed in the cross section. In FIG. 1 (c), the uneven surface 6 is formed in a cross section in such a manner that triangular convex portions and concave portions are alternately adjacent to each other. Reference numeral 7 denotes sludge attached to the inner surface of the capillary tube 4, that is, the uneven surface 6.

In the refrigeration cycle configured as described above, the inner surface of the capillary tube 4 constituting the expansion mechanism is formed by the uneven surface 6 having a step of a concave portion and a convex portion of 10 μm to 25 μm. And H which does not contain chlorine
When an ester oil or an ether oil compatible with the FC-based refrigerant and the HFC-based refrigerant is used, sludge 7 is generated. However, this sludge 7 is the capillary tube 4
, That is, the roughness on the inner surface of the capillary tube 4 does not change significantly.

Therefore, since the flow path resistance on the inner surface of the capillary tube 4 does not increase, it is possible to prevent the heat exchange capacity from decreasing due to the decrease in the refrigerant flow rate, the discharge pressure from rising, and the discharge temperature from increasing. Thereby, even if the generated sludge 7 adheres, the desired performance as a refrigeration cycle can be maintained.

Embodiment 2 In another embodiment of the present invention, the expansion mechanism is a polytetrafluoroethylene tube having high water repellency and corrosion resistance. In such a configuration, even if sludge 7 is generated, sludge 7
Does not adhere to the inner surface unlike ordinary capillary tubes. Therefore, an increase in flow path resistance on the inner surface of the expansion mechanism does not occur. For this reason, it is possible to prevent a problem such as a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant, and it is possible to maintain the desired performance as a refrigeration cycle.

Embodiment 3 FIG. 2 is a view showing an example of another embodiment of the present invention. FIG. 2 (a) is a cross-sectional view along the length of the pipe, and FIG. 2 (b) shows a state of manufacturing the pipe of FIG. 2 (a). It is a front view explaining. In addition, other than FIG.
A refrigeration cycle is configured in the same manner as described above. In the figure, 8 is a pipe, 9 is a polytetrafluoroethylene rod, and a spiral groove 10 is provided on the peripheral surface and fitted into the pipe 8. 11
Is a thin flow path spirally formed by the inner surface of the pipe 8 and the groove 10.

In the refrigeration cycle configured as described above, the flow path 11 of the expansion mechanism is formed by the groove 10 of the polytetrafluoroethylene rod 9 having high water repellency and corrosion resistance. For this reason, sludge 7 does not adhere to the inner surface unlike a normal capillary tube.

Therefore, since the flow path resistance does not increase on the inner surface of the expansion mechanism, it is possible to prevent a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the refrigerant flow rate. The intended ability can be maintained. Further, in the embodiment of FIG. 2, since the polytetrafluoroethylene rod 9 is fitted in the pipe 8 having high pressure resistance, a required pressure resistance can be easily obtained.

Embodiment 4 FIG. 3 also shows an example of another embodiment of the present invention, and is a cross-sectional view along the length of a capillary tube. The refrigeration cycle is configured in the same manner as in FIG. 6 except for FIG. In the drawing, reference numeral 12 denotes a large-diameter portion formed inside the inlet side of the capillary tube 4, and 6 denotes a concave-convex surface formed on the inner surface of the large-diameter portion 12 of the capillary tube 4, which is concave in a direction along the inner surface of the large-diameter portion 12. And the convex portions are arranged at substantially equal intervals, and the step between the concave portions and the convex portions is formed in a range of 10 μm to 25 μm. 7 is the large diameter part 1
The sludge adhered to the inner surface of No. 2, that is, the uneven surface 6.

In the refrigeration cycle configured as described above, the concave and convex surface 6 capable of accumulating the maximum amount of sludge 7 adhering to the capillary tube 4 during the life cycle of an air conditioner or the like is formed on the capillary tube 4. It is provided on the entrance side of. Thereby, the sludge 7 is collected on the uneven surface 6 on the inlet side of the capillary tube 4, so that the sludge 7 does not adhere to the main longitudinal portion of the capillary tube 4.

For this reason, since the flow path resistance does not increase on the inner surface of the capillary tube 4, it is possible to prevent the occurrence of problems such as a decrease in heat exchange capacity, a rise in discharge pressure, and a rise in discharge temperature due to a decrease in the flow rate of the refrigerant. As a result, the desired performance as a refrigeration cycle can be maintained.

Embodiment 5 FIG. 4 also shows an example of another embodiment of the present invention. FIG. 4 (a) is a refrigerant circuit diagram showing a refrigeration cycle in which a plurality of capillary tubes are provided in parallel, and FIG. FIG. 5 is a refrigerant circuit diagram showing a refrigeration cycle in which the capillary tubes are provided in series. In the figure, 1 is a compressor, 2 is a four-way valve, 3 is an indoor heat exchanger, and 41 is a first capillary tube.

In FIG. 4A, reference numeral 42 denotes a second capillary tube arranged in parallel with the first capillary tube 41, and in FIG. 4B, reference numeral 43 denotes a second capillary tube arranged in parallel with the first capillary tube 41. It is a capillary tube. 5 is an outdoor heat exchanger.

In FIG. 4A, reference numeral 13 denotes a switching valve arranged in series with the second capillary tube 42;
4 (b), reference numeral 14 denotes a switching valve arranged in parallel with the first capillary tube 41, in FIG. 4 (a), numeral 15 denotes a differential pressure sensor arranged in parallel with the first capillary tube 41, and FIG. Is a differential pressure sensor arranged in parallel with the first capillary tube 41 and the second capillary tube 43.

In the refrigeration cycle configured as described above, the first capillary tube 41 and the second capillary tube 42 are arranged in parallel, and the first capillary tube 41 and the second capillary tube 43 are arranged in series. Further, a switching valve 13 and a switching valve 14 are arranged in series or in parallel to these capillary tubes.

When the sludge 7 adheres to the capillary tube and the flow path resistance increases, the flow path resistance is detected by the differential pressure sensor 15, the differential pressure sensor 16 or the like, or a predetermined integrated operation time is used. , Switching valve 1
3. Open / close the switching valve 14 to switch the passing capillary tube.

In this way, an increase in flow path resistance on the inner surface of the capillary tube is suppressed. Therefore,
It is possible to prevent the occurrence of problems such as a decrease in heat exchange capacity, a rise in discharge pressure, and a rise in discharge temperature due to a decrease in the flow rate of the refrigerant, and it is possible to maintain the expected performance as a refrigeration cycle and guarantee long-term operation. be able to.

Embodiment 6 FIG. Further, as an example of another embodiment of the present invention, a large step uneven surface having a large step between a concave portion and a convex portion is formed on the inner surface of the capillary tube in the configuration of the embodiment of FIG. Then, in the early stage of the operation, a flow path is formed on the uneven surface of the large step, and the sludge is positively attached and captured. Then, the flow path of this capillary tube is switched to another capillary tube by the switching valve 13 and the switching valve 14. Also in this case, similarly to the case described above, an increase in flow path resistance on the inner surface of the capillary tube can be suppressed, and long-term operation can be guaranteed.

Embodiment 7 FIG. 5 also shows an example of another embodiment of the present invention, and is a refrigerant circuit diagram showing a refrigeration cycle. In the figure, 1 is a compressor, 2 is a four-way valve, 3
Is an indoor heat exchanger, 4 is a capillary tube, 5 is an outdoor heat exchanger, and 17 is a shutoff valve provided at a connection portion at both ends of the capillary tube 4 in the refrigerant circuit.

In the refrigeration cycle configured as described above, the closing valves 17 are respectively provided at the connecting portions at both ends of the capillary tube 4 and the capillary tube 4 as an expansion mechanism.
Is provided. Then, when the sludge 7 adheres to the capillary tube 4 and the flow path resistance increases, the capillary tubes 4 are easily replaced without closing the closing valves 17 at both ends of the capillary tube 4 without discharging the refrigerant. be able to. Therefore, maintenance costs,
Repair costs can be reduced.

[0035]

As described above, the present invention comprises a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly containing a soluble ester or ether is enclosed. Then, the inner surface of the capillary tube constituting the inflation mechanism is set to 10 μm to 25 μm.
It is formed by an uneven surface composed of a step of a concave portion and a convex portion of μm.

The HFC refrigerant containing no chlorine and H
Sludge is generated when an ester oil or an ether oil compatible with the FC-based refrigerant is used. However, even if this sludge adheres to the inner surface of the capillary tube, that is, the uneven surface, the roughness on the inner surface of the capillary tube does not change significantly.

Therefore, since the flow path resistance on the inner surface of the capillary tube does not increase, it is possible to prevent the heat exchange capacity from decreasing due to the decrease in the refrigerant flow rate, the discharge pressure from rising, and the discharge temperature from increasing. This allows
Even if the generated sludge adheres, the refrigeration cycle has the effect of maintaining the expected performance.

Further, as described above, the present invention comprises a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly containing a soluble ester or ether is enclosed. The expansion mechanism is constituted by a polytetrafluoroethylene tube.

Thus, even if sludge is generated in the expansion mechanism, it does not adhere to the inner surface unlike a normal capillary tube. Therefore, an increase in flow path resistance on the inner surface of the expansion mechanism does not occur. For this reason, it is possible to prevent a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant, and to maintain the desired performance as a refrigeration cycle.

Further, as described above, the present invention comprises a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly containing a soluble ester or ether is enclosed. The expansion mechanism is constituted by a polytetrafluoroethylene rod in which a spiral groove is provided in the pipe and the peripheral surface, which is fitted into the pipe, and which forms a narrow spiral flow path by the inner surface of the pipe and the groove. is there.

The channel of the expansion mechanism is constituted by a groove of a polytetrafluoroethylene rod having high water repellency and corrosion resistance. For this reason, even if sludge is generated in the expansion mechanism, it does not adhere to the inner surface unlike a normal capillary tube. Therefore, an increase in flow path resistance on the inner surface of the expansion mechanism does not occur.

For this reason, it is possible to prevent a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant, thereby maintaining the desired performance of the refrigeration cycle. In addition, since a polytetrafluoroethylene rod is fitted in a pipe having high pressure resistance, there is an effect that a required pressure resistance is easily obtained.

Further, as described above, the present invention comprises a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly containing a soluble ester or ether is enclosed. Further, a capillary tube having an uneven surface is provided on the inner surface of the large-diameter portion formed on the inlet side, which constitutes an expansion mechanism.

As a result, the sludge of the expansion mechanism is collected on the uneven surface on the inlet side of the capillary tube.
No sludge adheres to the longitudinal main part of the capillary tube. For this reason, an increase in flow path resistance on the inner surface of the capillary tube does not occur. Therefore, it is possible to prevent a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant, thereby maintaining the desired performance of the refrigeration cycle.

Further, as described above, the present invention comprises a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator. A lubricating oil mainly containing a soluble ester or ether is enclosed. In addition, both the first capillary tube and the second capillary tube constituting the expansion mechanism and a switching valve arranged corresponding to at least one of these two tubes are provided.

When the sludge adheres to the capillary tube and the flow path resistance increases, the flow through the capillary tube is switched by the switching valve by the flow path resistance detection means or a preset integrated operation time. Thus, an increase in flow path resistance on the inner surface of the capillary tube is suppressed. Therefore, it is possible to prevent the occurrence of problems such as a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant. In addition, there is an effect of maintaining normal operation for a long time.

As described above, according to the present invention, a large step uneven surface having a large step between a concave portion and a convex portion is formed on one inner surface of both the first capillary tube and the second capillary tube. A flow path that passes through a large uneven surface at the beginning of operation is formed.

Then, at the beginning of the operation, after the sludge is positively attached to and trapped on the uneven surface of the large step, the capillary tube having the uneven surface of the large step is switched to another capillary tube by a switching valve. Thus, an increase in flow path resistance on the inner surface of the capillary tube is suppressed. Therefore, it is possible to prevent the occurrence of problems such as a decrease in the heat exchange capacity, a rise in the discharge pressure, and a rise in the discharge temperature due to a decrease in the flow rate of the refrigerant. In addition, there is an effect of maintaining normal operation for a long time.

Further, in the refrigeration cycle according to the present invention, a refrigerant mainly composed of an HFC-based refrigerant containing no chlorine and comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, A lubricating oil mainly containing a soluble ester or ether is enclosed. In addition, shut-off valves are provided at connection portions at both ends of the capillary tube constituting the expansion mechanism.

When the sludge adheres to the capillary tube and the flow path resistance increases, the capillary tubes can be easily replaced without releasing the refrigerant by closing the closing valves at the connection portions at both ends of the capillary tube. be able to. Therefore, there is an effect of reducing maintenance costs and repair costs.

[Brief description of the drawings]

FIG. 1 is a view showing Embodiment 1 of the present invention, and is a cross-sectional view along the length of a capillary tube.

FIG. 2 is a diagram showing a third embodiment of the present invention;
2A is a cross-sectional view along the length of the pipe, and FIG.
The front view explaining the production situation of the piping of (a).

FIG. 3 is a view showing a fourth embodiment of the present invention, and is a cross-sectional view along a length of a capillary tube.

FIG. 4 is a diagram showing a fifth embodiment of the present invention.
4A is a refrigerant circuit diagram showing a refrigeration cycle in which a plurality of capillary tubes are provided in parallel, and FIG. 4B is a refrigerant circuit diagram showing a refrigeration cycle in which a plurality of capillary tubes are provided in series.

FIG. 5 is a diagram showing a seventh embodiment of the present invention, and is a refrigerant circuit diagram showing a refrigeration cycle.

FIG. 6 is a refrigerant circuit diagram showing a conventional refrigeration cycle.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Compressor, 4 capillary tubes, 41 First capillary tube, 42 Second capillary tube, 6 Uneven surface, 8 Piping, 9 Polytetrafluoroethylene rod, 10 Groove, 11 Channel, 12 Large diameter portion, 13
Switching valve, 17 closing valve.

Claims (7)

[Claims] 1. A refrigerant comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, comprising a refrigerant containing a chlorine-free HFC-based refrigerant as a main component and an ester or ether having a compatibility with the refrigerant as a main component. A refrigerating cycle comprising a capillary tube in which a lubricating oil is filled and an inner surface is formed by a concave-convex surface having a step of a concave portion and a convex portion of 10 μm to 25 μm to constitute the expansion mechanism. 2. A refrigerant comprising a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, the refrigerant comprising an HFC-based refrigerant containing no chlorine as a main component and an ester or ether having a compatibility with the refrigerant as a main component. A refrigeration cycle in which a lubricating oil is filled and the expansion mechanism is constituted by a polytetrafluoroethylene tube. 3. A refrigerant composed of a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, which is mainly composed of a chlorine-free HFC-based refrigerant and an ester or ether compatible with the refrigerant. The expansion mechanism is filled with a spiral groove in the pipe and the peripheral surface, and fitted into the pipe to form a narrow flow path that forms a spiral by the groove with the inner surface of the pipe. Refrigeration cycle composed of tetrafluoroethylene rods. 4. A refrigerant composed of a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, and mainly composed of an HFC-based refrigerant containing no chlorine and an ester or ether compatible with the refrigerant. A refrigerating cycle comprising a capillary tube in which a lubricating oil is filled and an uneven surface is provided on an inner surface of a large-diameter portion formed on an inlet side to constitute the expansion mechanism. 5. A refrigerant composed of a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, and mainly composed of a chlorine-free HFC-based refrigerant and an ester or ether compatible with the refrigerant. And a refrigerating cycle comprising: a first capillary tube and a second capillary tube constituting the expansion mechanism; and a switching valve arranged corresponding to at least one of the two. 6. A large-level uneven surface having a large step between a concave portion and a convex portion is formed on one inner surface of both the first capillary tube and the second capillary tube, and the large-level uneven surface is formed by a switching valve at an early stage of operation. 6. A refrigeration cycle according to claim 5, wherein a flow path passing through the refrigeration cycle is formed. 7. A refrigerant composed of a compressor, a four-way valve, a condenser, an expansion mechanism, and an evaporator, and mainly composed of a chlorine-free HFC-based refrigerant and an ester or ether compatible with the refrigerant. A refrigerating cycle, wherein a lubricating oil is sealed, and a shut-off valve is provided at each of connection portions at both ends of a capillary tube constituting the expansion mechanism.