JPH09113180A - Water-free welding method for refrigerant piping in heat-exchanger and refrigerant circuit for heat-exchanger formed by water-free welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a production cost and prevent lowering of durability due to mixture of steam of cooling water in a refrigerant piping by a method wherein, in coupling of the refrigerant piping to refrigerant inlet and outlet, a work to weld in a state of a heat-exchanger being immersed in cooling water is eliminated and an energy loss due to cooling is prevented. SOLUTION: In a method to weld refrigerant pipings 7 and 7 to refrigerant inlet and outlet 3 and 2 of a heat-exchanger 1, heat dissipation pipes 4 and 4 are located between the refrigerant inlet and outlet 3 and 2 and the refrigerant pipings 7 and 7. The heat dissipation pipe 4 and the refrigerant pipings 7 and 7 are coupled together by heating welding and the heat dissipation pipes 4 and 4 and the refrigerant inlet and outlet 3 and 2 are connected together by local welding.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for anhydrous welding of a refrigerant circuit in a heat exchanger and a refrigerant circuit in a heat exchanger formed by anhydrous welding.

[0002]

2. Description of the Related Art A heat exchanger 1 shown in FIG. 4 is used when heat is exchanged between a refrigerant and a liquid such as water in a refrigerant circuit, and is of a laminated type. This laminated heat exchanger 1 is
A plurality of plate bodies having a flat flow path inside are stacked, communication holes are provided at both ends thereof, and a brazing material is interposed between the plate bodies so that the communication holes are stacked, and this is laminated.
It is formed by brazing a plate body by heating in a furnace with a brazing material interposed between the plate bodies. Further, a refrigerant inlet 3 and an outlet 2 communicating with the flow path are formed on the outermost side in the stacking direction by brazing to the communication holes.

When a refrigerant circuit is formed using the heat exchanger 1 constructed as described above, about 850 parts of the refrigerant pipes 7 and 7 and the refrigerant inlet 3 and outlet 2 are to be joined together. Brazing is performed after heating to ℃.
At this time, the brazing part of the heat exchanger 1 (especially the refrigerant inlet 3
In order to prevent the heating and the brazing portion of the outlet 2 from being melted by this heating, the portion excluding the refrigerant inlet 3 and the outlet 2 is immersed in the cooling water W to prevent the temperature of the heat exchanger 1 from rising.

[0004]

Usually, the refrigerant inlet and outlet of the heat exchanger are made of stainless steel, and the refrigerant pipe is often made of copper. Such dissimilar metals are locally welded such as arc welded. Therefore, when attempting to weld, voids are likely to occur at the joint interface, and moreover, an embrittlement compound is formed and weakens. In order to prevent this, welding by brazing is performed.

However, as described above, by cooling the portion of the heat exchanger excluding the refrigerant inlet and outlet by immersing it in the cooling water, the temperature of the heat exchanger itself is prevented from rising and the refrigerant is introduced into the refrigerant inlet and outlet. The pipe is brazed (an example of heat welding). This has a problem that it is extremely troublesome and time-consuming. Further, since the heat is cooled by the cooling water, there is a problem that energy loss is large and the cost is high. Furthermore, when the cooling water vapor is mixed in the heat exchanger and the vapor removal after the formation of the refrigerant circuit is incomplete, a part of the refrigerant chemically reacts to generate acid and corrode the inside of the refrigerant pipe early. There is a problem that the durability of the refrigerant pipe is deteriorated.

The present invention has been made in view of the above problems, and when connecting the refrigerant pipes to the refrigerant inlet and outlet of the heat exchanger, it is extremely troublesome and time-consuming to immerse the heat exchanger in cooling water and perform welding. Eliminating the work that takes a lot of time,
By eliminating the energy loss due to cooling, while reducing the production cost, it is possible to prevent the deterioration of durability caused by the mixture of the cooling water vapor into the refrigerant pipe anhydrous welding method of the refrigerant pipe of the heat exchanger and An object of the present invention is to provide a refrigerant circuit of a heat exchanger formed by anhydrous welding.

[0007]

In order to achieve the above object, according to the method of anhydrous welding of the refrigerant pipe in the heat exchanger of claim 1, the refrigerant pipe is welded to the refrigerant inlet and the refrigerant outlet of the heat exchanger. A method, wherein a heat radiation pipe is interposed between the refrigerant inlet and the refrigerant outlet and the refrigerant pipe, the heat radiation pipe and the refrigerant pipe are connected by heat welding, and the heat radiation pipe and the refrigerant inlet and the refrigerant outlet are connected. The means of connecting by local welding was taken.

According to the refrigerant circuit in the heat exchanger of claim 2, the refrigerant pipe for supplying the refrigerant from the compressor is connected to the refrigerant inlet of the heat exchanger, and the refrigerant is circulated to the compressor at the refrigerant outlet. A refrigerant circuit in a heat exchanger formed by connecting refrigerant pipes, wherein a radiator pipe is interposed between the refrigerant inlet and the refrigerant outlet and the refrigerant pipe, and the radiator pipe and the refrigerant pipe are connected by heat welding. Then, the means for forming the heat radiating pipe by connecting the refrigerant inlet and the refrigerant outlet by local welding.

Incidentally, the local welding is a method of locally raising the temperature to a high temperature by applying a voltage to the portions to be welded and fusing the metal of the portions to be welded, or colliding an electron beam with the portions to be welded. It is a method of fusing the metal of the portion to be welded by the collision heat. For example, arc welding,
Laser welding, electron beam welding, etc. Further, the heat welding refers to a method in which the entire parts to be joined are heated to melt the welding member. For example, brazing or the like.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 in FIGS. 1 to 3 denotes a heat exchanger used when cooling a high-temperature and high-pressure refrigerant with a liquid such as water in a refrigerant circuit, and is a laminated type. In this laminated heat exchanger 1, a plurality of plates having flat flow passages are stacked inside each other, communication holes are provided at both ends thereof, and the communication holes are arranged between the plates so that the communication holes are overlapped with each other. It is formed by laminating materials by interposing them and heating them in a furnace to braze the plate body with the brazing material interposed between the plate bodies. Furthermore, a refrigerant inlet 3 and an outlet 2 made of stainless steel, which communicate with the flow path, are attached to the outermost side in the stacking direction by brazing.

Further, reference numeral 4 in the drawing is a radiating pipe made of stainless steel. The radiating pipes 4 and 4 are formed such that the outer diameter on one side can be inserted into the refrigerant inlet 3 and the outlet 2, and the inner diameter on the other side can be inserted into the refrigerant pipes 7 and 7 described later. Is formed in.

Further, reference numerals 7 and 7 in the figure are refrigerant pipes made of copper. The refrigerant pipes 7 and 7 form a closed loop refrigerant circuit via the compressor 8, the heat exchanger 1 on the condensation side and the heat exchanger 10 on the evaporation side. The symbol A in FIG. 1 indicates the entire mechanism of the refrigerant circuit.

In order to form the closed loop refrigerant circuit, as shown in FIGS. 2 and 3, the refrigerant inlet 3 and the outlet 2 of the heat exchanger 1, the refrigerant pipes 7 and 7, and the heat radiation pipes 4 and 4 are formed. It is connected in the following procedure. , Refrigerant pipe connecting step One end side of the refrigerant pipes 7, 7 is inserted into one side opening of the heat dissipation pipes 4, 4. , Brazing process Part 4 to be joined between the heat radiation pipes 4 and 4 and the refrigerant pipes 7 and 7.
The entire peripheral surfaces of a and 4a are heated to about 850 ° C., and by this heating, the brazing material is melted and poured evenly into the portions 4a and 4a to be joined. It should be noted that the above brazing is also preferably performed in an inert gas such as argon gas or helium gas. Radiating pipe connecting step The other side of the radiating pipes 4, 4 connected to the refrigerant pipes 7, 7 in the brazing step is inserted into the openings of the refrigerant inlet 3 and the outlet 2. , Arc welding process Refrigerant inlet 3 and outlet 2 are connected to the heat radiating pipes 4 connected to the heat radiating pipes 7 by the heat radiating pipe connecting process. The local portions of the portions 2a and 3a to be heated are heated to about 1200 ° C. and welded. The welding in this step is preferably performed in an inert gas such as argon gas or helium gas.

In the brazing steps of the above-mentioned steps, after the entire peripheral surfaces of the portions 4a, 4a to be joined are preheated to 850 ° C., the entire peripheral surfaces of the portions 4a, 4a to be joined are brazed. However, during brazing, the brazing part is separate from the heat exchanger 1, so the heat applied during brazing is not transferred to the heat exchanger 1 and the heat exchanger 1
There is no risk that the brazing material will reach a temperature at which it will melt again.

In the arc welding process, it is not necessary to heat the entire peripheral surfaces of the portions 2a and 3a to be joined as in brazing welding, and the portions to be joined between the heat radiation pipes 4 and 4 and the refrigerant inlet 3 and outlet 2 are to be joined. Since a voltage is applied to the local portions of 2a and 3a to locally raise the temperature to fuse the metals to be joined, only the local portions of the refrigerant inlet 3 and the outlet 2 of the heat exchanger 1 are heated, and the heat exchange is performed. The brazing part of the vessel 1 (especially the brazing parts of the refrigerant inlet 3 and the outlet 2) does not rise to a temperature at which the brazing material remelts.

Therefore, the portions 2a, 3a, 4a, 4 to be joined in the brazing process and the arc welding process are
Due to the heat applied to a, the brazing part of the heat exchanger 1 does not rise to a temperature at which the brazing material melts again, so that the heat exchanger 1 is not immersed in the cooling water W (see FIG. 4), and It is possible to weld between the inlet 3 and the outlet 2 and the refrigerant pipes 7, 7.

That is, the extremely troublesome and troublesome work of welding the heat exchanger 1 while immersing it in the cooling water W can be eliminated, and the energy loss due to cooling at the time of welding can be eliminated to reduce the production cost. In addition, since the cooling water W is not used, there is no risk that the steam of the cooling water W will mix into the heat exchanger 1, and the refrigerant generated by the mixing of the steam of the cooling water W into the heat exchanger 1. It is possible to prevent deterioration of durability of the piping and the refrigerant circuit formed by the piping.

When the one ends of the heat radiating pipes 4 and 4 are heated to a temperature suitable for brazing, the temperature of the other end of the radiating pipes 4 and 4 is the temperature at which the brazing material is melted by the heat radiation of the radiating pipes 4 and 4. The brazing process may be performed after performing the arc welding process if the length does not rise up to 1.

Further, when the vapor of the cooling water W is mixed in the refrigerant circuit and the vapor removal after the formation of the refrigerant circuit is incomplete, a part of the refrigerant chemically reacts to generate an acid and the inside of the refrigerant pipe. May corrode in the early stages to deteriorate the durability of the refrigerant pipe, or rust caused by moisture may enter the compressor 8 and cause the compressor 8 to malfunction, and the moisture may freeze during the expansion process of the refrigerant. There is a risk of malfunctioning.

Further, the arc welding in the arc welding step is a welding which is performed by locally applying heat to a portion to which a voltage is applied, and the welding method is not limited to arc welding as long as the welding method locally applies heat. Needless to say, for example, electron beam welding using impact heat of an electron beam may be used.

In the above-described embodiment, the steps from 1 to 3 are described only for the heat exchanger 1 on the condensation side, but if the pipes are connected by brazing, the heat exchanger 1 on the condensation side is used.
It is needless to say that the heat radiation pipes 4 and 4 may be similarly interposed in the piping of the heat exchanger 10 on the evaporation side. Reference numerals 5 and 6 in FIG. 1 denote an outlet and an inlet of a heat exchange liquid for exchanging heat with the refrigerant.

[0022]

EFFECTS OF THE INVENTION According to the method for anhydrously welding a refrigerant pipe in a heat exchanger according to the present invention and the refrigerant circuit in the heat exchanger formed by the anhydrous welding, a heat radiating pipe is provided between the refrigerant pipe and the refrigerant inlet and outlet. By interposing, the connection part between the heat radiation pipe and the refrigerant inlet and outlet is locally welded, and the connection part between the refrigerant pipe and the heat radiation pipe is heat welded. The brazing material does not rise to a temperature at which it melts again. Therefore, it is possible to eliminate the extremely troublesome and time-consuming work of welding while immersing the heat exchanger in cooling water, energy loss due to cooling at the time of welding is eliminated, and the production cost can be reduced. Since no cooling water is used,
It is possible to prevent the deterioration of the durability of the refrigerant pipe and the refrigerant circuit formed by the refrigerant pipe caused by the mixing of the cooling water vapor.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method of anhydrous welding of a refrigerant pipe in a heat exchanger according to the present invention and a refrigerant circuit in a heat exchanger formed by anhydrous welding.

FIG. 2 is a perspective view showing a welded state of a refrigerant inlet and outlet of a heat exchanger, a heat radiation pipe, and a refrigerant pipe.

FIG. 3 is an enlarged sectional view of an essential part of a welded state of a refrigerant inlet and outlet of a heat exchanger, a heat radiating pipe, and a refrigerant pipe.

FIG. 4 is an explanatory diagram of a method for connecting a refrigerant pipe of a conventional heat exchanger.

[Explanation of symbols]

 1 Heat Exchanger 2 Refrigerant Outlet 3 Refrigerant Inlet 4 Radiator Pipe 7 Refrigerant Pipe

Claims (2)

[Claims] 1. A method for welding a refrigerant pipe to a refrigerant inlet and a refrigerant outlet of a heat exchanger, wherein a heat radiating pipe is interposed between the refrigerant inlet and the refrigerant outlet and the refrigerant pipe, and the heat radiating pipe and the refrigerant pipe are connected to each other. A method for anhydrous welding of refrigerant pipes in a heat exchanger, wherein the heat-dissipating pipes and the refrigerant inlet and the refrigerant outlet are connected by local welding. 2. A refrigerant in a heat exchanger formed by connecting a refrigerant pipe for supplying a refrigerant from a compressor to a refrigerant inlet of the heat exchanger and connecting a refrigerant pipe for circulating the refrigerant to the compressor to the refrigerant outlet. In the circuit, a heat dissipation pipe is interposed between the refrigerant inlet and the refrigerant outlet and the refrigerant pipe, and the heat dissipation pipe and the refrigerant pipe are connected by heat welding,
A refrigerant circuit in a heat exchanger, characterized in that the radiating pipe is connected to the refrigerant inlet and the refrigerant outlet by local welding.