JP2017110265A - On-off valve for fluid and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead-less on-off valve having no stress corrosion crack and an air conditioner using the same.SOLUTION: An air conditioner has a constitution by forming an on-off valve with a bras alloy which has content of lead of 1000 ppm or less and contains Sn of 0.8% or more and arranging the same in a refrigerant circuit. Thereby stress corrosion crack can be prevented and environmental load can be reduced even in the on-off valve which is used by installing the same to a refrigerant piping, is exposed to ambient air rich in ammonia and is easy to react with ammonia with higher temperature than ambient air.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fluid on-off valve such as a two-way valve or a three-way valve interposed in a refrigerant piping system of a refrigeration cycle, and more particularly to an on-off valve capable of reducing an environmental load and an air conditioner using the same.

  In general, a device using a refrigeration cycle, for example, an air conditioner, is configured by connecting an indoor unit and an outdoor unit by a refrigerant pipe, and the refrigerant circuit has a service port for air purge and refrigerant filling after the pipe is connected. A three-way valve is provided (see, for example, Patent Document 1).

  FIG. 7 shows an air conditioner described in Patent Document 1. This air conditioner is configured by connecting an outdoor unit 100 and an indoor unit 101 with refrigerant pipes 103a and 103b, and a connecting portion of the refrigerant pipes 103a and 103b. In addition, a two-way valve 104 and a three-way valve 105 are interposed. Then, the service port 106 of the three-way valve 105 is opened and closed to perform air purge and refrigerant filling after pipe connection (paragraph 0044 of Patent Document 1).

JP 2009-250274 A

  The conventional air conditioner can perform air purge without leaking the refrigerant by using the three-way valve 105, and can be constructed without causing a load on the environment by leaking the refrigerant. There are advantages.

  However, since the two-way valve 104 and the three-way valve 105 are complicated in shape and require high precision, the two-way valve 104 and the three-way valve 105 are made of a material with good workability and are currently formed of a brass alloy containing lead. This brass alloy is a suitable material for complicated and highly accurate on-off valves because of its excellent properties such as corrosion resistance, machinability, and mechanical properties, but because it contains lead, the on-off valves have a large environmental impact. It has become.

  Therefore, it is conceivable that the on-off valve is a brass alloy on-off valve that can be said to be substantially lead-free with a lead content of 1000 ppm or less.

  However, if the on-off valve is lead-free, the brass alloy constituting the on-off valve reacts with ammonia contained in the atmosphere and stress corrosion cracking occurs.

  In particular, fluid on-off valves such as two-way valves and three-way valves that are used in refrigerant piping are provided in outdoor units and are constantly exposed to the atmosphere. Since the ammonia generated from the excrement of small animals is easily touched, the above-described stress corrosion cracking is likely to occur.

  In addition, fluid on-off valves such as two-way valves and three-way valves that are used by interposing in the refrigerant pipes have a temperature of about 60 ° C. and much higher than the atmosphere due to the refrigerant flowing in the on-off valves. Therefore, the sensitivity to the reaction with ammonia is increased, and stress corrosion cracking is likely to occur.

  Accordingly, the present invention has been promoted to lead-free in consideration of these points, and a substantially lead-free fluid on-off valve that prevents stress corrosion cracking at a practical level and an air conditioner using the same. It is for the purpose of provision.

  In the present invention, in order to achieve the above object, a fluid on-off valve is formed of a brass alloy having a lead content of 1000 ppm or less and containing 0.8% or more of Sn.

  Thereby, even if it is a fluid on-off valve that is exposed to the atmosphere containing a lot of ammonia by being interposed in the refrigerant pipe, and the temperature is higher than the atmosphere and the reaction with ammonia tends to proceed, Stress corrosion cracking can be prevented.

  The present invention can prevent stress corrosion cracking of a fluid on-off valve while reducing the environmental load, and can improve the reliability of a fluid on-off valve and an air conditioner using the same.

Refrigerant circuit diagram of the air conditioner in Embodiment 1 of the present invention (A) Front view showing appearance of outdoor unit of same air conditioner, (b) Side view showing part of piping cover of outdoor unit broken away Sectional view showing the three-way valve of the air conditioner Exploded sectional view showing the three-way valve of the air conditioner Photograph showing test state of test product of the present invention Sectional drawing which shows the two-way valve of the air conditioner in Embodiment 2 of this invention Refrigerant circuit diagram of a conventional air conditioner

  In the first invention, the fluid on-off valve is formed of a brass alloy having a lead content of 1000 ppm or less and containing Sn of 0.8% or more.

  As a result, even if it is an on-off valve for a fluid that is exposed to the atmosphere containing a lot of ammonia and is easily exposed to the atmosphere due to its temperature being higher than the atmosphere and being easily reacted with ammonia. Cracking can be prevented.

  According to a second invention, in the first invention, the fluid on-off valve is further formed of a brass alloy containing 1.6% or more of Bi.

  Thereby, even if it is a lead-less brass alloy, favorable workability can be maintained by Bi.

  In a third aspect of the present invention, a fluid on-off valve is formed of a brass alloy having a lead content of 1000 ppm or less and containing Si in an amount of 0.001% or more (excluding 0.001%).

  As a result, even if it is an on-off valve for a fluid that is exposed to the atmosphere containing a lot of ammonia and is easily exposed to the atmosphere due to its temperature being higher than the atmosphere and being easily reacted with ammonia. Cracking can be prevented.

  A fourth invention is an air conditioner provided with the fluid on-off valve according to any one of the first to third inventions.

  Thereby, stress corrosion cracking of the fluid on-off valve can be prevented, and the environmental load can be reduced without reducing the reliability of the fluid on-off valve and the air conditioner using the fluid on-off valve.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a refrigerant circuit diagram of an air conditioner according to Embodiment 1 of the present invention, FIG. 2 is (a) a front view showing the appearance of the outdoor unit of the air conditioner, and (b) one of piping covers of the outdoor unit. FIG. 3 is a sectional view showing a three-way valve of the air conditioner, and FIG. 4 is an exploded sectional view showing the three-way valve of the air conditioner.

  1, the air conditioner in the present embodiment includes a compressor 1 that compresses refrigerant, a four-way valve 2 that switches a refrigerant circuit during cooling and heating operation, an outdoor heat exchanger 3 that exchanges heat between the refrigerant and the outside air, and refrigerant. An outdoor unit 5 having a decompressor 4 for reducing the pressure, an indoor unit 7 having an indoor heat exchanger 6 for exchanging heat of refrigerant and indoor air, and a liquid connection pipe 8 for connecting the indoor unit 7 and the outdoor unit 5. And gas connection pipe 9. And the 1st on-off valve 10 is the piping between the connection port to the gas connection piping 9 of the outdoor unit 5 and the four-way valve 2, and the piping between the connection port to the liquid connection piping 8 and the decompressor 4. The second on-off valves 11 are provided respectively.

  The compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the decompressor 4, the second on-off valve 11, the liquid connection pipe 8, the indoor heat exchanger 6, the gas connection pipe 9, and the first on-off valve 10 Are connected in an annular shape with piping to constitute a refrigerant circuit.

  The first on-off valve 10 is constituted by a three-way valve that performs air purge and refrigerant filling after pipe connection, and the second on-off valve 11 is constituted by a two-way valve. As shown in FIG. 2, each of the on-off valves 10 and 11 is provided so as to be exposed on the side surface of the outdoor unit 5 and covered with the piping cover 5a, but is exposed to the atmosphere at a position close to the ground or the like. It has become a form. Each of the on-off valves 10 and 11 is formed by forging using a brass alloy.

  In the refrigerant circuit constituting the air conditioner according to the present embodiment, tetrafluoropropene or trifluoropropene is used as a base component, difluoromethane, pentafluoroethane or tetrafluoroethane is used, and the global warming potential is 5 or more and 750. A hydrofluoroolefin refrigerant with a small environmental load, which is preferably a mixture of two components or a mixture of three components so that it is preferably 350 or less, more preferably 150 or less, is used. Specifically, a single refrigerant of a HFC refrigerant such as R32, a hydrogen fluoride refrigerant having a carbon double bond such as HFO-1234yf, or a mixed refrigerant containing them as a main component is used.

  During the cooling operation, the four-way valve 2 is switched so that the discharge side of the compressor 1 and the outdoor heat exchanger 3 communicate with each other. Thereby, the refrigerant | coolant compressed by the compressor 1 turns into a high temperature / high pressure refrigerant | coolant, and is sent to the outdoor heat exchanger 3 through the four-way valve 2. FIG. Then, it exchanges heat with the outside air to dissipate heat, and becomes a high-pressure liquid refrigerant, which is sent to the decompressor 4. In the decompressor 4, the pressure is reduced to form a low-temperature and low-pressure two-phase refrigerant, which is sent to the indoor unit 7 through the second on-off valve 11 and the liquid connection pipe 8. In the indoor unit 7, the refrigerant enters the indoor heat exchanger 6, exchanges heat with indoor air, absorbs heat, evaporates, and becomes a low-temperature gas refrigerant. At this time, the room air is cooled to cool the room. Further, the refrigerant returns to the outdoor unit 5 through the gas connection pipe 9, and returns to the compressor 1 through the first on-off valve 10 and the four-way valve 2.

During the heating operation, the four-way valve 2 is switched so that the discharge side of the compressor 1 and the first on-off valve 10 communicate with each other. Thereby, the refrigerant compressed by the compressor 1 becomes a high-temperature and high-pressure refrigerant, passes through the four-way valve 2, the first on-off valve 10, and the gas connection pipe 9 and is sent to the indoor unit 7. The high-temperature and high-pressure refrigerant enters the indoor heat exchanger 6, exchanges heat with indoor air, dissipates heat, and is cooled to become high-pressure liquid refrigerant. At this time, the room air is heated to heat the room. Thereafter, the refrigerant passes through the liquid connection pipe 8 and is sent to the second on-off valve 11 and the decompressor 4, and is decompressed by the decompressor 4 to become a low-temperature and low-pressure two-phase refrigerant and sent to the outdoor heat exchanger 3. It exchanges heat with the outside air to evaporate and returns to the compressor 1 via the four-way valve 2.

  Next, the configuration of the first on-off valve 10 that is one of the fluid on-off valves used in the air conditioner of the present embodiment will be described with reference to FIGS.

  The first on-off valve 10 is a three-way valve, and its valve body 21 has an indoor piping side port 22, an outdoor piping side port 23, a service port 24, and a valve rod receiving portion 26 into which a valve rod 25 is screwed. Is provided.

  A gas connection pipe 9 connected to the indoor heat exchanger 6 is connected to the indoor pipe side port 22 via a flare nut 27, and a copper pipe 28 is brazed to the outdoor pipe side port 23 via a flux agent. Similarly, it is connected to a pipe 29 (see the refrigerant circuit diagram of FIG. 1) from the outdoor heat exchanger 3 side.

  A valve core 30 is inserted into the service port 24 and a service port cap 31 is screwed thereon. Although normally sealed, the service port 24 is evacuated when the air conditioner is installed.

  A valve stem cap 32 is screwed onto the valve stem receiving portion 26 to prevent dust from entering the valve stem receiving portion 26 from the outside. As shown in FIG. 4, the valve rod 25 in the valve rod receiving portion 26 is integrally provided with a groove portion 25 d that interposes a male screw portion 25 a, a hexagon wrench insertion hole 25 b, and an O-ring 25 c. The male threaded portion 25a of the valve stem 25 is screwed with a female threaded portion 26a provided in the valve stem receiving portion 26, and a hexagonal wrench (not shown) is inserted into the hexagonal wrench insertion hole 25b for rotational operation. Thus, the valve stem 25 can be advanced and retracted to open and close the outdoor piping side port valve seat 23a.

  The valve body 21 of the three-way valve configured as described above is formed by forging using a brass alloy as described above, and the brass alloy is a lead-less brass alloy having a lead content of 1000 ppm or less.

  As described in the background art, the lead-free brass alloy having a lead content of 1000 ppm or less reacts with ammonia to cause stress corrosion cracking when the brass alloy constituting the on-off valve contained in the atmosphere reacts with ammonia.

  Therefore, in this invention, the on-off valve has a lead content of 1000 ppm or less, Sn is 0.220% or more (excluding 0.220%), and preferably Bi is 1.320% or more (1 (Not including 320%) lead-free brass alloy.

  Table 1 shows the results of an ammonia stress corrosion cracking test conducted to evaluate stress corrosion cracking of a three-way valve formed of the leadless brass alloy.

In the test, as shown in FIG. 5, a vent plate is placed above the ammonia water in a desiccator containing 14% ammonia water, and a test product to be described later is placed on the vent plate to expose the test product in an ammonia atmosphere. After leaving for 72 hours, the sample was taken out, washed with a nitric acid solution, and visually observed. As a result of observation, a sample having no cracks is indicated by ○, and a sample having cracks is indicated by ×. Note that the distance t between the upper surface of the ammonia water and the ventilation plate is about 100 mm, and the test product is not in contact with the ammonia water.

  The test product is a three-way valve shown in FIG. 2. The dimensions and tightening torque of each part of the indoor piping side port 22, the service port 24, and the valve rod receiving part 26 are as shown in Table 2.

  As stress corrosion cracking, the indoor piping side port 22 portion and the flare nut 27 having a large tightening torque are the most severe conditions. Therefore, the evaluation was performed based on the results of the indoor piping side port 22 portion and the flare nut 27.

  From this test result, even if it is a lead-less brass alloy with a lead content of 1000 ppm or less, stress corrosion cracking can be prevented by using a brass alloy containing Sn of 0.8% or more, preferably 1.050% or more. I understand.

  As a result, it is exposed to a fluid on-off valve such as a two-way valve or a three-way valve that is used in the refrigerant piping, that is, exposed to the atmosphere rich in ammonia, and reacts with ammonia at a higher temperature than the atmosphere. Even if it is an easy on-off valve for fluid, stress corrosion cracking can be prevented.

  In addition, as shown in this embodiment, a single refrigerant of an HFC refrigerant such as R32 or a hydrogen fluoride refrigerant having a carbon double bond such as HFO-1234yf or a low global warming coefficient based on them. In an air conditioner using a refrigerant, the refrigerant compression pressure by the compressor is high, so that it receives a high compressive stress compared to a conventional on-off valve used in an air conditioner using a 410A refrigerant, for example. Can also strongly prevent stress corrosion cracking. Therefore, the environmental load can be greatly reduced by adopting the low warming potential refrigerant and using the lead-less brass alloy on-off valve.

  In addition, if Sn is contained excessively, a nest is generated inside the cast product, and the machinability is lowered or the elongation is lowered. Therefore, it is preferably 2.5% or less, preferably 2.0% or less ( Sn: 0.220% or more (excluding 0.220%) to 2.5% or less).

  Bi may be 1.320% or more (excluding 1.320%), preferably 1.890% or more. Since this Bi has the property of improving machinability, the inclusion of this Bi can suppress deterioration of workability such as cutting caused by the lead-less brass alloy, thereby having a plurality of ports. Therefore, the productivity of the on-off valve that forms a screw on the inner and outer peripheries of the port can be increased, which is preferable. If this Bi is contained excessively, the tensile strength and elongation are lowered, so it is preferable to make it less than 2.120% (Bi: 1.320% or more (not including 1.320%) to 2.120%. Less than).

  In addition, as shown in Table 1, the lead-less brass alloy used in the above test has Cu of 58.300% to 61.720%, Sn of 0.220% to 1.050% or less, and Bi of 1.320. % Or more (not including 1.320%) to less than 2.120%, and the balance is made of Zn and impurities, but Cu is 59.500% or more (including 59.500%) from the viewpoint of workability and the like. No.) and good up to 66.00% (Cu: 59.500% or more (excluding 59.500%) to 66.00% or less).

(Embodiment 2)
This embodiment shows another example of a lead-less brass alloy release valve that suppresses stress corrosion cracking with a lead content of 1000 ppm or less.

  The lead-less brass alloy of this on-off valve is a brass alloy having a lead content of 1000 ppm or less and containing Si, preferably containing 0.001% or more of Si, more preferably containing 3.060% or more of Si. An on-off valve is formed.

  Table 3 shows the results of the ammonia stress corrosion cracking test conducted to evaluate the stress corrosion cracking of the three-way valve formed of the leadless brass alloy.

  In the test, a vent plate is placed in a desiccator containing 14% ammonia water as in the case of the first embodiment, and a test product to be described later is placed thereon to expose the test product in an ammonia atmosphere. After being left for a period of time, it was taken out, washed with a nitric acid solution, and visually observed. As a result of observation, a sample having no cracks is indicated by ○, and a sample having cracks is indicated by ×. The distance t between the upper surface of the ammonia water and the intermediate plate is about 100 mm, and the test product is in a non-contact state with the ammonia water.

  The test product is a three-way valve shown in FIG. 2, and the dimensions and tightening torque of each part of the indoor piping side port 22, the service port 24, and the valve rod receiving part 26 are as shown in Table 2 described in the first embodiment. It is.

  In this embodiment as well, the indoor piping side port 22 portion and the flare nut 27 having a large tightening torque are the most severe conditions for stress corrosion cracking. It evaluated with the result of.

  From this test result, even if it is a lead-less brass alloy having a lead content of 1000 ppm or less, Si is 0.001% or more, and more preferably Si is 3.060% or more. Since stress corrosion cracking resistance is improved, stress corrosion cracking can be prevented. The Si improves the stress corrosion cracking resistance and also improves the machinability. However, if it exceeds 4.0%, the machinability improvement effect corresponding to that cannot be obtained, so it is less than 4.0%. (Si: 0.001% or more and less than 4.0%) is preferable.

  Thus, as in the first embodiment, the fluid on-off valve used by being interposed in the refrigerant pipe, that is, exposed to the atmosphere rich in ammonia, and reacts with ammonia at a higher temperature than the atmosphere. Even if it is an easy on-off valve for fluid, stress corrosion cracking can be prevented.

  In addition, the lead-less brass alloy used in the above test has a Cu content of 59.060% to 75.170% and a Si content of 0.001% or more as shown in Table 3 (in other words, at least Si is contained). If it is ˜3.060% or more and the balance is made of Zn and impurities and Si is 3.060% or more, the Cu content may be up to 79%, preferably up to 75.170% (Cu: 59.060% or more (excluding 59.060%) to 79% or less).

(Embodiment 3)
FIG. 6 shows a fluid on-off valve in Embodiment 3, which is a two-way valve. This two-way valve includes an indoor piping side port 22, an outdoor piping side port 23, and a valve rod receiving portion 26 into which a valve rod 25 is screwed.

  A liquid connection pipe 8 connected to the indoor heat exchanger 6 is connected to the indoor pipe side port 22 via a flare nut 27, and a copper pipe 28 is brazed to the outdoor pipe side port 23 via a flux agent. Similarly, it is connected to the pipe 29a (see the refrigerant circuit diagram of FIG. 1) from the outdoor heat exchanger 3 side.

  The brass alloy constituting this two-way valve is formed of the leadless brass alloy described in the first embodiment or the leadless brass alloy described in the second embodiment.

  Therefore, the same operational effects as those of the first embodiment or the second embodiment are obtained.

As described above, the fluid on-off valve and the air conditioner using the fluid on-off valve according to the present invention have been described using the above embodiment, but the present invention is not limited to this. That is, the embodiment disclosed this time should be considered as an example and not restrictive. That is, the scope of the present invention is shown not by the above description but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  In addition, the said air conditioner points out the apparatus carrying a refrigerating cycle, and it cannot be overemphasized that apparatuses, such as a dehumidifier and a heat pump water heater, are included in addition to a general air conditioner.

  As is apparent from the above description, the present invention can provide a fluid on-off valve free from stress corrosion cracking even with a lead-less brass alloy, and an air conditioner using the same. The environmental load can be reduced without lowering the reliability of the equipment including the conditioner and equipped with the refrigeration cycle.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Four-way valve 3 Outdoor heat exchanger 4 Pressure reducer 5 Outdoor unit 6 Indoor heat exchanger 7 Indoor unit 8 Liquid connection piping 9 Gas connection piping 10 1st on-off valve (fluid on-off valve)
11 Second on-off valve (fluid on-off valve)
21 Valve body 22 Indoor piping side port 23 Outdoor piping side port 24 Service port 25 Valve rod 26 Valve rod receiving part 27 Flare nut 28 Copper tube 29, 29a Piping 30 Valve core 31 Service port cap 32 Valve rod cap

Claims (4)

A fluid on-off valve formed of a brass alloy having a lead content of 1000 ppm or less and containing Sn of 0.8% or more. The on-off valve for fluid according to claim 1, wherein the on-off valve is further formed of a brass alloy containing 1.6% or more of Bi. A fluid on-off valve having a lead content of 1000 ppm or less and formed of a brass alloy containing Si. The air conditioner which provided the on-off valve of any one of Claims 1-3 in a refrigerant circuit.

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