JP2003130240A - Fusable plug, manufacturing method thereof and freezer comprising it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fusable plug not containing a toxic substance such as Cd or Pd, being high in reliability, having a lower cost than a relief valve and correspondable to a next generation refrigerant, and to provide a manufacturing method thereof and a freezer comprising it. SOLUTION: This fusable plug comprises a plug member formed of a body having a relief hole penetrating the freezer and low melting point metal fixed on the relief hole so as to block the relief hole. The low melting point metal has a solidus line temperature higher than a temperature for the refrigerant included in the freezer and is formed by bismuth (Bi), indium (In) and tin (Sn).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusible plug used as a safety device for a refrigeration system, a method for manufacturing the fusible plug, and a refrigeration system equipped with the same.

[0002]

2. Description of the Related Art FIG. 1 shows an example of a refrigerating apparatus. This refrigeration system comprises a refrigeration cycle in which a compressor 1, which is configured as a high-pressure side pressure vessel, a condenser 2, a liquid reservoir 3, an expansion valve 4, and a heat exchanger 5 are sequentially connected. The insides of the condenser 2 and the liquid reservoir 3 show almost the same pressure and temperature. When the temperature or pressure of the refrigerant inside the side wall of the condenser 2 or the liquid reservoir 3 rises for some reason, the plug member 6 made of a low melting point metal is softened and melted, and the condenser 2 and the liquid as a pressure vessel A fusible plug 7 is attached as a safety device that prevents the condenser 2 and the liquid reservoir 3 from exploding by releasing the refrigerant in the reservoir 3 into the outside air.

FIG. 2 and FIG. 3 show a schematic structure of the fusible plug 7, which has been generally used in the past. That is, FIG. 2 is a perspective schematic view of the fusible plug 7, and FIG. 3 is attached to a condenser (hereinafter, referred to as a condenser or a pressure vessel) 2 or a liquid reservoir 5. It is sectional drawing of the fusible plug 7 of FIG. 2 in a state.

As shown in these figures, the fusible plug 7 is
An escape hole 6a for conducting the inside and outside of the condenser (pressure vessel) 2,
Screw part 6b for attachment to condenser or liquid reservoir, and condenser 2
Alternatively, it is composed of a main body 6 having a collar portion 6c which constitutes a contact when it is attached to the liquid reservoir 3, and a plug member 8 held so as to close the escape hole 6a in the main body 6. The plug member 8 is fixed and held by pouring the melted low melting point metal into the escape hole 6a and cooling and solidifying the low melting point metal in the escape hole 8a.

In this refrigeration system, the high-temperature and high-pressure gas refrigerant compressed by the compressor 1 is condensed by exchanging heat with air or water in the condenser 2 to become a high-temperature and high-pressure liquid refrigerant, and a part thereof. Are stored in the liquid reservoir 3. This liquid refrigerant is used in the expansion valve 4
Is sent to the heat exchanger 5 to be decompressed and becomes a low temperature low pressure liquid-gas mixed refrigerant and flows into the heat exchanger 5. And with this heat exchanger 5,
After exchanging heat with a cooling object such as water and vaporizing, it is compressed again by the compressor 1 to become a high-temperature and high-pressure gas refrigerant, which is circulated again in the refrigerant circuit.

At this time, the condenser (pressure vessel) of the plug member 8
A high-temperature and high-pressure refrigerant flows in contact with a surface (hereinafter, referred to as a pressure receiving surface) 8a exposed to the space of 2 or the liquid reservoir 3 in a continuous flow state. The pressure P of this refrigerant (this pressure is
(Acting in a direction perpendicular to the pressure receiving surface 8a) is determined by the refrigerant, and the pressure P and temperature of the refrigerant repeatedly change irregularly during operation of the refrigerator. Therefore, the plug member 8 is subjected to an irregularly changing pressure on the pressure receiving surface 8a, and is further irregularly heated by the refrigerant having an irregular temperature change. A part of the stopper member 8 is the main body 6
There is a concern that it may be exposed to the outside of the container (referred to as "jumping out"), or that the plug member 9 may protrude in the direction of L in the drawing at a temperature below the operating design temperature to cause refrigerant leakage (referred to as "airtight leakage"). It had been.

Further, the fusible stopper of the conventional refrigerating apparatus is a refrigeration safety regulation-related standard (Ordinance of the Ministry of Economy, Trade and Industry) and JIS B820.
Based on No. 4, each company's various designs are performed according to the refrigerant used. Refrigerants used in refrigeration equipment are HF with zero ozone depletion potential due to global regulations on ozone depleting substances.
Alternatives to C (Hydro, Fluoro-Carbons) -based refrigerants are in progress.

The fusible plug used in the refrigerating apparatus is based on the above-mentioned relational standard and JIS B8204,
It is common practice to fill a fusible plug body with an alloy having a solidus temperature higher than the working temperature of the refrigerant and a liquidus temperature lower than the critical temperature as a low melting point alloy. However, these are the cases where the operating temperature of the fusible plug is 75 ° C. or lower, and when it exceeds this, another condition must be satisfied, which is disadvantageous in terms of reliability and cost.

However, in addition to R404A, R125, which is mentioned as a refrigerant that is currently regarded as a promising refrigerant,
R143a, R407B, R410A, R410B, R
All of 507A and the like have a critical temperature of 75 ° C. or lower, and a refrigerant operating temperature of 57 ° C. or higher.

Since the design pressure of the refrigeration system and the critical temperature of the refrigerant of the fusible plug used in the refrigeration system differ depending on the refrigerant, it is necessary to redesign the operating temperature when the refrigerant switches. Note that the design pressure of the refrigeration system complies with the above-mentioned relational standard, and is substantially uniquely determined at the same time as the selection of the refrigerant for a certain model.

For example, R404A (HFC12) which is one of the promising next-generation HFC refrigerants
5, a mixed refrigerant of HFC143 and HFC134a), in the case of an air conditioning refrigeration system, the design pressure is about 3
MPa (saturation temperature of the refrigerant at this pressure is about 63 ° C)
And the critical temperature of this R404A is about 72 ° C.
In this case, the difference between the operating temperature and the critical temperature is only 9 ° C.

Table 1 shows R22 (HCFC system) and R404A estimated from the standards related to the freezing and safety regulations (Ordinance of the Ministry of Economy, Trade and Industry).
(HFC system), estimated use temperature (pressure) of ammonia (natural refrigerant), and estimated critical temperature (pressure) are shown.

[Table 1]

When the difference between the operating temperature of the refrigerant and the critical temperature is relatively small, the operability of the fusible plug operating below the critical temperature and the inoperability of not operating under the operating temperature and operating pressure of the refrigerant ( It is difficult to satisfy both the requirement for creep resistance) and in order to achieve this, as a low melting point alloy used for the fusible plug, 13.5 wt% tin (Sn) and 27 wt% lead ( Pb), 50 wt% bismuth (Bi), 9.
There was a tendency to easily select an alloy containing toxic substances such as Cd and Pb, such as an alloy containing 5% by weight of cadmium (Cd).

However, the harmfulness of Cd has been known for a long time, and its use is regulated including disposal.
Further, the harmfulness of Pb has recently become a problem, and regulations on its use are being studied worldwide.

However, in the alloy containing no harmful substances Cd and Pb, the details of the reaction form have not been clarified yet. Therefore, depending on the alloy system used, a low-temperature melting phase appears, and a usual low-temperature melting phase appears. Some of them soften under the operating conditions of the refrigeration system, and when applied to a fusible plug, they may malfunction at a predetermined temperature or lower.

As an example of an alloy containing no harmful substances Cd and Pb, there is a known example of In-Bi-Sn alloy.
For example, Japanese Patent Application Laid-Open No. 8-154093 discloses an In-Bi-Sn alloy having a liquidus temperature not higher than the heat resistant temperature of the materials to be joined as a solder material for mounting electronic components. However, this alloy is merely one that considers the joining of electronic components and printed circuit boards and the like.

The present inventors have studied to apply the In-Bi-Sn alloy to the fusible plug and applied for a patent. Specifically, it is a fusible plug used in a temperature range of 57 ° C. or higher and 65 ° C. or lower and provided in a refrigerating device in which a refrigerant having a critical temperature of 75 ° C. or lower is sealed. A main body having an escape hole that penetrates the inside and outside of the device,
A plug member made of a low melting point metal fixed to the escape hole so as to close the escape hole, wherein the composition of the low melting point metal is Sn: X wt%, In: Y wt%, balance Bi XSn-YIn- (100-XY) Bi
And 4 ≦ X ≦ 10 and 56 ≦ Y ≦ 63.

[0018]

However, it is highly possible that the refrigerant will be replaced by natural refrigerants such as ammonia, which has not only zero ozone depletion potential but also zero global warming potential in the future. It is not always used in a temperature range of ℃ or below, and it does not necessarily have a critical temperature of 75 ℃ or below.

Further, in the above invention, even if the fusible stopper is manufactured by the same manufacturing process by using the low melting point metal having the same composition,
The solidification structure changes due to variations in the filling profile of the low-melting-point metal, which causes variations in creep resistance (here, the time until the occurrence of airtight leakage is referred to, not the time until the occurrence of airtight leakage). As a result, the airtightness is likely to vary, and a more homogeneous meltable stopper corresponding to the above-mentioned refrigerant having a more uniform solidified structure has been desired. For this reason, the allowable composition variation range of the low melting point metal is also very small, and it is necessary to strictly control the low melting point metal material, so that there is a problem that the cost of the raw material is high.

The present invention has been made in view of the above technical problems, and its purpose is to be compatible with various refrigerants, to contain no harmful substances such as Cd and Pb, and to have variations in creep resistance. To provide a fusible plug corresponding to a next-generation refrigerant having a small size, a manufacturing method thereof, and a refrigerating apparatus including the same.

[0021]

Means for Solving the Problems The inventors of the present invention have conducted extensive research based on the above-mentioned invention to produce a low melting point metal containing Bi, In, and Sn as main components, and describe the composition and the process for filling the metal. By controlling, it has been found that it is possible to provide a fusible plug corresponding to various refrigerants and a refrigeration apparatus including the fusible plug.

The first fusible plug of the present invention is a plug member made of a main body having an escape hole penetrating the inside and outside of a refrigerating apparatus, and a low melting point metal fixed to the escape hole so as to close the escape hole. And the low melting point metal has a solidus temperature equal to or higher than the working temperature of the refrigerant provided in the refrigerating apparatus,
Bismuth (Bi), indium (In) and tin (S
n) is a fusible plug.

The second fusible plug of the present invention is a fusible plug characterized by having a composition in which the above In content is not more than 50% by weight.

In the third fusible plug of the present invention, the Bi content is 40% by weight or more and 50% by weight or less, the In content is 30% by weight or more and 45% by weight or less, and the balance is Sn. A fusible plug having a composition.

The fourth fusible plug of the present invention is a fusible plug characterized in that fine metal particles are added to the low melting point metal.

A fifth soluble plug according to the present invention is characterized in that the fine metal particles are made of at least one substance selected from Ag, Zn, Ni, Cu, Au, Sb and P. Is.

A sixth method for manufacturing a fusible plug according to the present invention comprises a main body having an escape hole penetrating the inside and outside of the refrigerating apparatus, and a low melting point metal fixed to the escape hole so as to close the escape hole. In the method for producing a fusible plug comprising a plug member made of, the escape hole is filled with a plug member made of the low melting point metal, the temperature of the low melting point metal at the time of completion of filling is the low melting point. It is a method for producing a fusible stopper, characterized in that the liquidus temperature of the metal is equal to or higher than the liquidus temperature.

The seventh method for producing a fusible plug of the present invention is characterized in that, when the above-mentioned low melting point metal is filled into the escape hole, the cooling rate after completion of filling is set to 50 ° C./min or less. .

An eighth refrigeration system of the present invention is a refrigeration system comprising a compressor, a condenser, a liquid reservoir, an expansion valve, and a heat exchanger, which circulates a refrigerant. The refrigerating apparatus is provided with the fusible plugs of 5 to 5.

The ninth refrigerating apparatus of the present invention is characterized in that a refrigerant having a critical temperature of 75 ° C. or lower is used as the refrigerant.

The tenth refrigerating apparatus of the present invention is characterized in that it uses, as the refrigerant, one that can be used at 57 ° C. or higher and 65 ° C. or lower.

An eleventh refrigerating apparatus of the present invention uses R125, R143a, R404A, R407 as the refrigerant.
At least one of B, R410A, R410B, and R507A is used.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to tables, but the present invention is not limited to these embodiments. In the following examples, operability and creep resistance were tested by the following methods. (Preparation of Soluble Plug for Test) Each fusible plug was subjected to a test of operability and creep resistance so that the fusible plug 7 had a pressure vessel side 8a (see FIG. 3).
To a nitrogen cylinder equipped with a pressure gauge and a pressure reducing valve, and when the scale of the pressure gauge indicates a pressure of 3 MPa, the pipe is sealed off, and this pressure (3 MPa) acts on the plug member 8. It was in a state to do. (Temperature Control) For temperature control, a water tank with variable water temperature was used. In addition, the water tank with variable water temperature has a width of about 300 mm and a length of about 500.
It has a size of mm and a height of about 25 mm, and the water temperature inside thereof is arbitrarily variable.

(Operational test) In the operational test, it was determined that the fusible stopper, which had been pressurized as described above, was immersed in the water tank kept at a predetermined water temperature for 1 minute, and if bubbles were observed, the operation was performed. However, if no bubbles were observed, it was determined that the operation did not occur. Then, when it operated at a temperature equal to or lower than the operation design temperature, it was marked as a pass, and when it did not operate, it was marked as a fail.

(Creep resistance test) Further, in the creep resistance test, the fusible plug under the above pressure was immersed in a water tank kept at a predetermined water temperature for a predetermined time, and bubbles or low-melting metal protrusions were observed. If so, it was judged that it worked, and if it was not observed, it was judged that it did not work. If it did not operate at the target temperature, it was judged to be acceptable, and if it operated, it was judged to be unacceptable. The test time was set to 2000 hours at maximum, but the test which passed 500 hours was regarded as passing. Each composition was tested by 10 pieces, and was marked as “◯” only when all the compositions passed.

In the test, a plurality of fusible plugs were prepared, and the above-mentioned operability or creep resistance test was conducted only once for each fusible plug.
The influence on the strength of the plug member 8 due to the repeated action on the above was avoided.

(Solid-line / Liquid-line temperature) In the curve obtained by the differential thermal analysis, the temperature of the lowest temperature side end of the first peak obtained at the time of temperature rise is taken as the solidus temperature, and at the time of cooling The temperature of the highest temperature side end of the obtained first peak was defined as the liquidus temperature.

Embodiment 1. (Examples 1 to 3) (Production of fusible plug) The fusible plug was prepared by placing the copper fusible plug body 6 heated to 250 ° C. on a gypsum board and 2 mmφ × 30.
Flux was applied to the tip of a low-melting metal rod having a composition, solidus temperature, and liquidus temperature of 0 mm shown in Table 2, and the inner wall of the fusible stopper body was brought into contact with the low-melting metal rod to fill it. The operability and creep resistance of the obtained fusible plug were measured. The operability test temperature was 71 ° C, and the creep resistance was 63 ° C. As a result, as shown in Table 2, it was confirmed that both the operability and the creep resistance passed.

[0039]

[Table 2]

Other than this, the estimated use temperature (pressure) and estimated critical temperature of the HCFC system, the HFC system, and the natural refrigerant were similarly examined by adjusting the Bi, In, and Sn ratios.
For all refrigerants other than H ₂ O (water) and CO ₂ (carbon dioxide), the effective amount of Bi, In, and Sn can be set to an effective amount having a solidus temperature equal to or higher than the refrigerant use temperature. Yes,
By doing this, it was confirmed that an alloy that satisfies the operability and creep resistance could be designed.

Experiments were carried out by mixing various metals as an alloy having the same melting point and creep resistance, but no composition containing no harmful Pb or Cd was found. In particular, the alloy of the present invention is less harmful than Pb and Cd, achieves a low melting point near 57 ° C., and exhibits sufficient wettability to the fusible plug body 6 which is often made of a copper alloy, Furthermore, it has the most important creep resistance. From the above, the significance of the alloy of the present invention according to claim 1 has been clarified.

Embodiment 2. (Examples 4 to 7) In the fusible plug 7 having the structure shown in FIGS. 2 and 3, the composition ratio of the Bi—In—Sn-based low melting point metal that constitutes the plug member 8 may be as shown in Table 3. The melt stopper was manufactured in the same manner as in Example 1. The solidus temperature, liquidus temperature, operability and creep resistance were measured, and the results are shown in Table 3. The operability was measured at 71 ° C., which is approximately equal to the critical temperature of R404A. The creep resistance was measured at 63 ° C., which is almost equal to the refrigerant temperature under the design pressure of R404A (about 3 MPa). As for the creep resistance test, 10 pieces of each composition were tested, and when all passed, they were marked with "◯". Also, the difference in creep resistance between the shortest life and the longest life is shown.

[0043]

[Table 3]

In Example 4, the creep resistance when the temperature at the time of completion of filling the low melting point metal was set to 68 ° C. was compared with that at 130 ° C. As a result, the temperature at the time of completion of filling was 68 ° C.
In the case of, there was variation in creep resistance.

In Example 4, assuming R404A,
The solidus temperature is higher than the refrigerant use temperature of 63 ° C, and the liquidus temperature is lower than the critical temperature of 71 ° C. In Comparative Example 1, R
The liquidus temperature of 404A is below the critical temperature, but the solidus temperature is lower than the working temperature of R404A. Examples 5-7
And Comparative Example 2 has In of 50 wt% or less, and Examples 5 to 7 have a solidus temperature higher than 63 ° C. and a liquidus temperature of 71 ° C. or less. As shown in Table 3, Example 4
In the fusible stopper of the present invention containing more than 50% by weight of In, both the operability and the creep resistance are passed, but there is a difference of 1500 hours in the pop-out condition of the stopper member 8 when the time exceeds 500 hours. Has also occurred, and I of Example 5
It can be seen that the variability is very large in comparison with 500 hours of the fusible plug of the present invention having an effective n amount of 50% by weight or less.

On the other hand, from the results of Examples 5 to 7, In was 5
It can be seen that in the composition range of 0 wt% or less, the composition range satisfying both the operability and the creep resistance is larger than the composition range containing In in an amount of more than 50 wt%. This is because by setting the In content to 50% by weight or less, the structure of the low melting point metal after filling the fusible plug was more homogeneous in the trial manufacturing process of this time, and the structure was observed to be excellent in creep resistance. Confirmed from. Therefore, it is understood that when the In content is 50% by weight or less, a fusible plug having a wide allowable composition variation range, excellent homogeneity, and excellent creep resistance can be obtained.

In Comparative Example 2, the solidus temperature is R404A.
Although the liquidus temperature was less than the critical temperature of R404A of 71 ° C or higher at the operating temperature of 63 ° C or lower, the operability was satisfied because the pressure was 3 MPa. However, since the operating temperature varies widely, it is desirable that the liquidus temperature of the low melting point metal be equal to or lower than the critical temperature of the refrigerant used. Further, most of the refrigerants currently used have operating temperatures of 57 ° C to 63 ° C and critical temperatures of 75 ° C or less. According to the above-mentioned relational criteria and JIS B8204, "when operating temperature is higher than 75 ° C. Must meet another condition,
The liquidus temperature is preferably 75 ° C. or lower because it is disadvantageous in terms of reliability and cost. From these facts and the results shown in Table 2, the content of Bi of 40 wt% or more and 50 wt% or less and In content of 35 wt% or more and 45 wt% or less of It can be seen that a more reliable and low cost fusible plug can be provided.

As described above, the refrigerating apparatus provided with the developed fusible plug is less harmful, highly reliable, and lower in cost than the safety valve provided. The installation position may be at least one of the compressor and the liquid reservoir. This device has high reliability and low cost by keeping the refrigerant temperature below 75 ° C.
In addition, R125, R143a, R404A, R4, which have higher reliability and have been standardized and whose performance has been ascertained by setting the refrigerant use temperature to 57 ° C. or higher and 65 ° C. or lower,
By using a refrigerant selected from at least one of 07B, R410A, R410B, and R507A, higher reliability can be achieved.

Embodiment 3. (Example 8) 20-40 at the time of producing the fusible plug using the low melting point metal of 42Bi-42In-16Sn (wt%) of the above-mentioned Example 5.
Ten solubilized stopper samples containing 0.02% by weight of Ni powder of 0.02% and no additive were prepared and subjected to the same operability and creep resistance test as described above. As a result, the operability of each soluble stopper sample was acceptable. The creep resistance was acceptable for all the samples, but the Ni-added sample was superior. Also, instead of Ni, Ag,
Using each powder of Zn, Cu, Au, Sb, and P, operability and creep resistance test were conducted. As a result, the same effect was confirmed. Similar results were obtained even if two or more kinds of powders were mixed and added.

Fourth Embodiment (Example 9) It was assumed that the filling completion temperature was 69 ° C, which was lower than the liquidus temperature, when the fusible plug was manufactured using the low melting point metal of 45Bi-40In-15Sn (wt%) in the above Example 7. Each of 10 pieces was prepared at 100 ° C., which is higher than the liquidus temperature, and the creep resistance was evaluated. As a result, all of the samples prepared below the liquidus temperature had a shorter life than the samples prepared above the liquidus temperature.

Embodiment 5. (Example 10) Table 4 shows 34Bi-61In- which is the fusible plug of Example 4.
5 shows the results of the same creep resistance test as that described above, in which 5Sn (% by weight; see Example 4 in Table 3) was filled in the fusible plug body at different maximum cooling rates. The cooling rate was tested in the following three ways. In addition,
The cooling rate was calculated from a chart in which a hole was formed in the body of the fusible plug, a K thermocouple was inserted, embedded with a silver paste, and sufficiently dried, and the temperature was continuously measured using a fully dried product. The fusible plug body was heated with a hot plate adjusted to a temperature of 250 ° C. A: Water cooling after filling low melting point metal (about 300 ° C / min) B: Air cooling after filling low melting point metal (about 50 ° C / min) C: Cooling on hot plate with power turned off after filling low melting point metal (Approx. 0.3 ° C / min)

[0052]

[Table 4] As a result, the creep resistance tends to be superior as the maximum cooling rate at the time of filling the low melting point metal is smaller. It can be seen that particularly at 50 ° C./min or less, a remarkable effect is exhibited.

Sixth Embodiment (Embodiments 11 and 12) (Embodiment 11) The fusible plug of Embodiment 2 is installed in a liquid reservoir of a general refrigerating machine having a compressor, a condenser, an expansion valve, a heat exchanger, and a liquid reservoir, and a refrigerant is used. Was operated at 63 ° C. using R404A as It was possible to operate for 5000 hours without any abnormality in the fusible plug.

(Embodiment 12) The fusible plug of Embodiment 1 is installed in the liquid reservoir of the same refrigerating machine as in Embodiment 11, and R22 is used as a refrigerant.
Operated at 64 ° C. No problem with the soluble plug 50
It was possible to operate for 00 hours.

[0055]

According to the first aspect of the present invention, there is provided a plug member composed of a main body having an escape hole penetrating the inside and outside of the refrigeration system, and a low melting point metal fixed to the escape hole so as to close the escape hole. And a main constitution of the low melting point metal,
Bismuth (Bi), indium (In), tin (S
n), which is a fusible stopper characterized in that its effective amount is an effective amount having a solidus temperature which is equal to or higher than the working temperature of the refrigerant provided in the refrigerating apparatus, and is therefore a harmful substance C
Provided is a fusible plug that does not contain d or Pb, is highly reliable, and is lower in cost than a safety valve and that is compatible with next-generation refrigerants.

According to a second aspect of the invention, the In content is 5
Since the fusible plug according to claim 1 has a composition of 0% by weight or less, variations in creep resistance are reduced and reliability is further enhanced. Further, since the allowable composition variation range can be widened and the expensive In content can be reduced, a fusible stopper at a lower cost can be provided.

According to the invention of claim 3, the content of Bi is 4
The content of In should be 30% or more and 50% by weight or less.
The soluble plug according to claim 1 or 2, wherein the content is at least 45% by weight and at most 45% by weight, and the balance is Sn. Therefore, since it can be operated particularly at 75 ° C or less, it is added separately. It is not necessary to carry out a test, and it is possible to provide a highly reliable and low cost fusible plug.

Since the invention of claim 4 is the fusible plug according to any one of claims 1 to 3, which is characterized in that metal fine particles are added, a more reliable fusible plug can be provided.

According to a fifth aspect of the invention, the metal fine particles are silver (Ag), zinc (Zn), nickel (Ni), copper (C).
u), gold (Au), antimony (Sb), phosphorus (P), the fusible plug according to claim 4, which is made of at least one or more kinds of substances, so that the reliability is further improved. Increase.

According to a sixth aspect of the present invention, when the escape metal is filled with the low melting point metal, the temperature of the low melting point metal at the time of completion of filling is
Since it is a method for producing a fusible plug, which is characterized by being at or above the liquidus temperature of the low melting point metal, it is possible to provide a fusible plug with improved reliability.

The invention according to claim 7 is characterized in that, when the escape hole is filled with the low melting point metal, the cooling rate after completion of filling is 50 ° C./minute or less. Since it is the manufacturing method described above, it is possible to provide a fusible stopper with further improved reliability.

According to the eighth aspect of the present invention, in a refrigerating apparatus comprising a compressor, a condenser, a liquid reservoir, an expansion valve, and a heat exchanger for circulating a refrigerant, the liquid reservoir and / or the condenser is any one of the first to fifth aspects. Since the refrigerating apparatus is provided with the fusible plug according to the item (1), it is possible to supply an environment-friendly and highly reliable refrigerating apparatus from which Cd and Pb have been removed.

According to a ninth aspect of the present invention, the refrigerant has a critical temperature of 75 ° C. or lower.

According to a tenth aspect of the present invention, the refrigerant is used at a temperature of 57 ° C. or higher and 65 ° C. or lower.

In the invention of claim 11, the refrigerant is R12.
5, R143a, R404A, R407B, R410
It is at least 1 sort (s) selected from the group which consists of A, R410B, and R507A, It is characterized by the above-mentioned.
Since it is the refrigerating apparatus according to any one, the reliability is further enhanced.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system.

FIG. 2 is a perspective view of the structure of a general fusible plug.

FIG. 3 is a cross-sectional view of the conventional fusible plug shown in FIG.

[Explanation of symbols]

1 compressor, 2 condenser, 3 liquid reservoir, 4 expansion valve, 5
Heat exchanger, 6 fusible plug body, 7 fusible plug, 8 plug member.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshio Umemura             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Yakuyo Ango             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Shiro Takatani             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F term (reference) 3H061 AA07 BB13 DD01 EA32 FA16                       GG20

Claims (11)

[Claims] 1. A refrigeration apparatus comprising: a main body having an escape hole penetrating the inside and outside of the refrigeration apparatus; and a plug member made of a low melting point metal fixed to the escape hole so as to close the escape hole.
The low melting point metal has a solidus temperature equal to or higher than a working temperature of a refrigerant included in the refrigerating apparatus and is composed of bismuth (Bi), indium (In) and tin (Sn), which is characterized by being soluble. plug. 2. The fusible plug according to claim 1, wherein the low melting point metal has an indium (In) content of 50% by weight or less. 3. The low-melting-point metal bismuth (Bi) content is 40% by weight or more and 50% by weight or less, and the indium (In) content is 30% by weight or more and 45% by weight or less,
The soluble plug according to claim 1 or 2, wherein the balance is tin (Sn). 4. The fusible plug according to claim 1, wherein fine metal particles are added to the low melting point metal. 5. The metal fine particles are silver (Ag), zinc (Zn), nickel (Ni), copper (Cu), gold (A).
The fusible stopper according to claim 4, which is made of at least one substance selected from the group consisting of u), antimony (Sb), and phosphorus (P). 6. A fusible plug, comprising: a main body having an escape hole penetrating the inside and outside of a refrigeration system; and a plug member made of a low melting point metal fixed to the escape hole so as to close the escape hole. In the method, the temperature of the low melting point metal at the time of completion of filling when filling the plug member made of the low melting point metal into the escape hole is equal to or higher than the liquidus temperature of the low melting point metal. And a method for producing a soluble stopper. 7. The method for producing a fusible plug according to claim 6, wherein a cooling rate after completion of the filling is set to 50 ° C./minute or less when the escape hole is filled with the low melting point metal. 8. A refrigerating apparatus comprising a compressor, a condenser, a liquid reservoir, an expansion valve, and a heat exchanger, which circulates a refrigerant, wherein the liquid reservoir and / or the condenser is one of claims 1 to 5. A refrigerating apparatus comprising a fusible plug. 9. The refrigerating apparatus according to claim 8, wherein the refrigerant has a critical temperature of 75 ° C. or lower. 10. The operating temperature of the refrigerant is 57 ° C. or higher and 6
It is 5 degrees C or less, The freezer of Claim 8 or 9 characterized by the above-mentioned. 11. The refrigerant is R125, R143a,
The refrigerating apparatus according to claim 8, wherein the refrigerating apparatus is at least one selected from the group consisting of R404A, R407B, R410A, R410B, and R507A.