JPH0815655B2 - Brazing method for refrigerant pipe joints - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method for a refrigerant pipe joint portion for joining a refrigerant pipe while completely preventing the formation of an oxide film inside the refrigerant pipe during brazing of the refrigerant pipe joint portion. Is.

[0002]

2. Description of the Related Art Conventionally, when brazing for joining refrigerant pipes, nitrogen gas is sent from one end of the refrigerant pipes to expel the air inside the refrigerant pipes so as to prevent an oxide film from forming on the inner surface of the joints for brazing work. However, when the inner diameter of the refrigerant tube is large, the tube length is long, and there are many bends, the air inside the refrigerant tube cannot be completely exhausted, and the formation of an oxide film could not be completely prevented. .

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to improve the effect of preventing the formation of an oxide film by brazing by satisfactorily venting the air inside the refrigerant tube. To do.

[0004]

In order to solve this problem, the present invention provides a refrigerant having a long pipe length and a large number of bent portions.
In the method of brazing the joint portion of the pipe, the airtightness of the joint portion of the refrigerant pipe is maintained, and after sucking the air inside the refrigerant pipe until the pressure inside the refrigerant pipe reaches a predetermined value, nitrogen gas is introduced inside the refrigerant pipe. A method of brazing a joint portion of a refrigerant pipe is characterized in that the joint portion of the refrigerant pipe is brazed by feeding in to confirm that the whole system is filled with nitrogen gas.

[0005]

With this configuration, the air inside the refrigerant pipe (liquid pipe, gas pipe) is completely extracted and replaced with nitrogen gas, and even if there are many bends in the liquid pipe and gas pipe, replacement with nitrogen gas is not possible. Completely done, it is possible to eliminate the generation of oxide film on the inner surface of the joint part due to brazing as in the past.
It does not adversely affect the function of air conditioning equipment.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an indoor unit, 2 is an outdoor unit, and these indoor unit 1 and outdoor unit 2 are connected to a liquid pipe 3 and a gas pipe 4.
The air conditioner is configured by connecting with. Bypass pipes 5, 6 and 7, 8 are provided in the vicinity of the connecting portions of the liquid pipe 3 and the gas pipe 4 to the indoor unit 1 and the outdoor unit 2, respectively, and the bypass pipes 5, 7 on the indoor unit 1 side are mutually connected. The bypass pipe 6 that is communicated with and protrudes from the liquid pipe 3 connection part side of the outdoor unit 2 is connected to an air extraction pipe 10 whose one end is connected to a vacuum pump 9, and the outdoor unit 2 gas pipe 4 connection part side. The bypass pipe 8 projecting from is connected to a nitrogen gas feed pipe 12 whose one end is connected to a nitrogen gas cylinder 11.

A vacuum gauge 13 is attached to the other end of the air extraction tube 10.
And a pressure gauge 14 for measuring the nitrogen gas pressure is connected to the other end of the nitrogen gas feed pipe 12. Reference numerals 15 and 16 are one-way valves provided in the middle of the air extraction pipe 10, and 17, 18
Is a one-way valve provided in the middle of the nitrogen gas feed pipe 12, 19 is a secondary pressure reducing valve also provided in the middle of the nitrogen gas feed pipe 12, and 20 is also provided in the middle of the nitrogen gas feed pipe 12. It is a primary pressure reducing valve. The nitrogen gas feed pipe 12 between the one-way valve 17 and the secondary pressure reducing valve 19 and the nitrogen gas feed pipe 12 between the secondary pressure reducing valve 19 and the primary pressure reducing valve 20 are respectively one-way valves. Pressure gauges 23 and 24 are connected via 21 and 22. Reference numeral 25 is an open valve connected via a one-way valve 27 to a connecting pipe 26 that connects the bypass pipe 6 projecting from the liquid pipe 3 connecting side of the outdoor unit 2 and the air extracting pipe 10. Numerals 28 and 29 are joint portions by brazing in the length direction of the liquid pipe 3 and the gas pipe 4.

Next, the brazing work process having the above configuration will be described. First, taping is performed with a vinyl tape so that air does not enter the fitting portions of the liquid pipe 3 and the gas pipe 4 to be brazed. The communication unit between the liquid pipe 3 and the gas pipe 4 for the indoor unit 1 and the outdoor unit 2 is closed by a valve (not shown) inside the indoor unit 1 and the outdoor unit 2, and then the one-way valve 17 , 18, 27 closed, one-way valve 15,
16, 21, 22 are opened, and the vacuum pump 9 is operated in this state to suck the air in the liquid pipe 3 and the gas pipe 4. After confirming that the gauge pressure of the vacuum gauge 13 dropped to near 0.76 mmAq, the one-way valve 16 was closed, and the gauge pressure of the pressure gauge 23 was 0.
The secondary pressure reducing valve 19 and the primary pressure reducing valve 20 are adjusted so as to be 5 to 1.0 mmAq. Next, open the one-way valves 17 and 18,
The nitrogen gas in the nitrogen gas cylinder 11 is replaced by the bypass pipe 8 and the gas pipe 4.
It is sent into the liquid pipe 3 from the bypass pipes 7 and 5 via.
Although it depends on the thickness, length, and bending state of the liquid pipe 3 and the gas pipe 4, it is confirmed by the open valve 25 that the entire system is filled with nitrogen gas, and then the one-way valve 15 is closed and the one-way valve is closed. 27 is opened quickly and the vacuum pump 9 is stopped. After that, the vinyl tape of the fitting portion to be brazed is removed, the fitting portion to be brazed is brazed, and the joint portions 28 and 29 are quickly cooled to room temperature with a wet cloth when the brazing is completed. As shown in the drawing, if there are multiple fitting parts to be brazed, do not remove the vinyl tapes at multiple locations at once, rather remove the vinyl tapes at each location to be brazed, braze and cool. Repeat the work. Once all brazing is complete, the primary pressure reducing valve
20 is closed, and work pipes such as the air extraction pipe 10 including the bypass pipes 5, 6 and 7, 8 are removed to complete the work.

[0009]

As described above, according to the present invention, the air inside the refrigerant pipe (liquid pipe, gas pipe) is completely extracted and replaced with nitrogen gas, and there are many bent portions of the liquid pipe and the gas pipe. However, the nitrogen gas is completely replaced, and it is possible to eliminate the generation of an oxide film on the inner surface of the joint due to the conventional brazing, and the function of the air conditioning equipment is not adversely affected.

[Brief description of drawings]

FIG. 1 is a piping diagram according to an embodiment of the present invention.

[Explanation of symbols]

 1 Indoor unit 2 Outdoor unit 3 Liquid pipe 4 Gas pipe 5, 6, 7, 8 Bypass pipe 9 Vacuum pump 10 Air extraction pipe 11 Nitrogen gas cylinder 12 Nitrogen gas feed pipe 13 Vacuum gauge 14 Pressure gauge 15, 16, 17, 18 1 Directional valve 19 Secondary pressure reducing valve 20 Primary pressure reducing valve 21,22 One-way valve 23,24 Pressure gauge 25 Open valve 26 Connection pipe 27 One-way valve 28,29 Joint

Claims (1)

[Claims] 1. A pipe with a long pipe length or a cold place with many bends
In the method of brazing the joint portion of the medium pipe, the airtightness of the joint portion of the refrigerant pipe is maintained, and after sucking the air inside the refrigerant pipe until the pressure inside the refrigerant pipe reaches a predetermined value, nitrogen is introduced inside the refrigerant pipe. A method for brazing a refrigerant pipe joint, comprising feeding gas, confirming that the entire system is filled with nitrogen gas, and brazing the joint of the refrigerant pipe.