Fluid handling – Processes – Cleaning – repairing – or assembling
Patent
1996-02-08
1999-03-23
Walton, George L.
Fluid handling
Processes
Cleaning, repairing, or assembling
29890131, 137315, 138142, 219 851, 219 8522, 228214, F16K 4300, B23K 104, B23K 3102
Patent
active
058846514
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a valve, having parts that are heat-sensitive above a limit temperature, a housing and at least one connecting tube to which a pipe is arranged to be soldered using local heating, and to a method for producing such a soldered joint.
In refrigeration systems, materials processing systems and similar systems, it is usual to join the expansion valves, magnetic valves, check valves and so on to their associated pipework by soldering. Copper pipes are used extensively for this pipework. The connecting tubes of the valves also consist of copper or a similar material. So that the heat-sensitive parts of the valve, for example, plastics parts, O-rings or a vapour, liquid or solid filling used in the valve are not damaged as the pipes are soldered together, previously, cooling had to be effected during the soldering operation. It is therefore usual to position so-called "cooling tongs" next to the soldering,point, or to wrap the valve housing in a damp cloth so that the valve housing does not become too hot.
The invention is based on the problem of simplifying the soldering operation.
This problem is solved according to the invention in that the connecting tube consists of a material of such low thermal conductivity that the heat-sensitive parts remain below the limit temperature as the heat required for soldering is applied.
SUMMARY OF THE INVENTION
When using such a connecting tube, it is possible to dispense with cooling through the use of cooling tongs, a damp cloth or similar means during the soldering operation. The connecting tube prevents the flow of heat to such a significant degree that the soldering operation has ended before the heat-sensitive parts have reached an inadmissibly high temperature. This effect can be yet further enhanced by the dimensions of the connecting tube (wall thickness, length).
The connecting tube advantageously consists of a material having a thermal conductivity below 80 W/.degree.K.multidot.m. Since the thermal conductivity of copper is 395 W/.degree.K.multidot.m, the thermal conductivity is reduced to a fifth or less.
In particular, the connecting tube may consist of stainless steel. Stainless steel is a recognized construction material and has a thermal conductivity of only 15 W/.degree.K.multidot.m, and is therefore especially suitable for the present purpose.
If the material of low thermal conductivity has relatively poor soldering properties, it is advisable for the connecting tube to be of hollow-cylindrical construction at its free end, and to carry a layer of solder on its face facing the pipe to be pushed into or onto it. The layer of solder which, when copper pipes are to be joined by soldering, expediently also consists of copper, ensures that the pipe is joined to the solder layer on the connecting tube in a firm and sealed manner by means of the solder that is supplied. A solder layer thickness of the order of 10 to 100 .mu.m is adequate, which impairs the overall thermal conductivity of the connecting tube only slightly even when the solder layer material has a good thermal conductivity.
It is already known from U.S. Pat. No. 4,415,187 to provide steel containers and other steel components of a refrigeration system with a tubular connecting tube of steel. To join on a copper pipe by soldering, the inner wall of the connecting tube is provided in the region of its free end with a soldered-in copper sleeve. No references are made to valves with heat-sensitive parts or to the exploitation of the low thermal conductivity of the steel.
It is furthermore advisable for the connecting tube to have a flange with which it is soldered to the housing. The flange provides a large-area soldering point which enables the wall thickness of the connecting tube to be less than when the connecting tube is being soldered into an opening of the housing.
It is especially advantageous for the connecting tube to be a deep-drawn part. Deep drawing allows much thinner wall thicknesses to be produced than a machining operation. Thermal
REFERENCES:
patent: 2763282 (1956-09-01), Reedy et al.
patent: 3188724 (1965-06-01), Bates et al.
patent: 3937245 (1976-02-01), Christie
patent: 4477955 (1984-10-01), Becker et al.
patent: 4573497 (1986-03-01), White
patent: 4601087 (1986-07-01), Kawai et al.
patent: 4813590 (1989-03-01), Deakin
patent: 5098010 (1992-03-01), Carmichael et al.
patent: 5557837 (1996-09-01), Thaird-Laforet et al.
Denning Henrik Thomas
Hansen Jens J.o slashed.rn
Vestergaard Anders
Danfoss A/S
Walton George L.
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