Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
  • F25B41/00—Fluid-circulation arrangements
  • F25B41/30—Expansion means; Dispositions thereof
  • F25B41/31—Expansion valves
  • F25B41/33—Expansion valves with the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant
  • F25B41/335—Expansion valves with the valve member being actuated by the fluid pressure, e.g. by the pressure of the refrigerant via diaphragms

Definitions

• Valve in particular expansion valve for refrigeration systems, and method for its production
• the invention relates to a valve, in particular expansion valve for refrigeration systems, with a housing and at least one connecting piece, which are connected to one another by soldering, and to a method for its production.
• the expansion valves on the market have a housing made of brass, into which connection pieces made of copper may be soldered. Such brass casings change color on the surface due to the so-called "patina”. This is undesirable in the food industry and for other applications. In addition, the visual impression suffers. For this reason it is known to provide the surface with a nickel layer. However, it is said that it can lead to health problems, namely to the very widespread nickel allergy. In addition, one carefully observes the heavy metals in the natural food chain, whereby nickel salts are suspected of being able to cause cancer.
• the invention has for its object to provide a valve of the type described above, which is more suitable for practice. This object is achieved in that at least the housing and all sockets are deep-drawn parts made of stainless steel, which is so low in carbon that it is practically insensitive to intergranular corrosion despite the heat treatment during soldering.
• Stainless steel as defined in DIN 17441, contains at least 12% chromium. It does not tend to discolour. It is environmentally friendly and does not give rise to health concerns. However, it is necessary to use a very low-carbon steel, because otherwise the heat treatment associated with the soldering process results in a sensitization (for example through the precipitation of chromium carbide) for the so-called intergranular corrosion that occurs in moist or steam-containing environments and finally the strength and tightness of the valve is affected. However, if you choose a low proportion of carbon, machining the steel becomes more difficult and more expensive than with larger amounts of carbon. For this reason, the housing and connector are designed as deep-drawn parts. Overall, this results in a valve (expansion valve, solenoid valve, non-return valve, etc.) that is not only suitable in refrigeration systems, but also in the food industry and under similar conditions of use.
• a valve expansion valve, solenoid valve, non-return valve, etc.
• the stainless steel can contain chromium and nickel and in particular can be a chromium-nickel-molybdenum steel.
• Nickel improves the deep-drawing and soldering properties.
• Molybdenum counteracts crevice and stress corrosion.
• the above-mentioned chromium carbides are formed at temperatures between 500 ° and 900 ° C, the highest precipitation rate being between 600 ° and 700 ° C. How long it is allowed to work in these areas depends on the carbon content of the steel. In particular, it is recommended that the stainless steel contain less than 0.05% C. Then a soldering time of 6 to 7 minutes is permissible, as is typical for a soldering process between 600 ° and 700 ° C. However, if the soldering is carried out at higher temperatures and the critical temperature range is passed faster during cooling, somewhat higher C components, such as 0.055 or 0.06% C, can also be accepted. Overall, a stainless steel is recommended, which essentially has the following composition:
• the stainless steel contains less than 0.05% C.
• the housing it is possible for the housing to have an outer flange on the end face to which the bottom ring of a membrane box, which is also deformed without cutting, is soldered or attached by laser welding. In addition to the nozzles, other non-cutting parts can also be attached to the housing.
• a copper-containing alloy and in particular a silver-containing copper solder known per se is recommended as the solder. You can therefore work with conventional soldering methods.
• At least some deep-drawn parts have a copper layer. This improves the soldering behavior. It is also advantageous that the sockets have on their inside a copper layer extending to the free end. Such a copper layer provides a tight and firm connection, particularly when a copper pipe is connected. Relatively small layer thicknesses of the order of 10 to are sufficient
• a method for producing a valve is characterized in that at least the housing and the at least one connecting piece made of flat boards, which consist of stainless, low-carbon steel, are deep-drawn and then soldered to one another. In mass production, the production of deep-drawn parts from such blanks is a particularly cheap manufacturing process.
• Fig. 2 nozzle and copper pipe when assembling
• Fig. 3 is a partial cross section through the membrane box.
• the illustrated valve 1 is an expansion valve for a refrigeration system. It has a housing 2 with three nozzles, namely a nozzle 3 for the inflowing liquid refrigerant, a nozzle 4 for the outflowing vaporous refrigerant and a nozzle 5 for connecting a sensor line. All nozzles have an outer flange 6, 7 and 8, with which they are soldered over a large area on the outside of the housing.
• One end of the housing 2 is closed by a membrane box 9, the bottom ring 10 of which is soldered to an outer flange 11 of the housing 2.
• a cover plate 12 of the membrane box is connected to a sensor 14 via a capillary tube 13.
• the membrane 15 is therefore from above under the evaporation pressure of the liquid in the sensor 14 and from below under the pressure of the refrigerant, which is detected on the nozzle 5, and a spring, not shown.
• All parts of the valve l shown in FIG. 1. are made of stainless steel with such a low carbon content that there are practically no precipitates on the finished valve that could later lead to intergranular corrosion.
• the housing 2 and the connecting pieces 3, 4 and 5 are formed as deep-drawn parts, while the base ring 10 and the cover 12 are stamped and stamped parts.
• X2CrNiMo17132 which improves the deep-drawing and soldering properties due to its nickel content and counteracts crevice and stress corrosion due to the low carbon content in connection with the molybdenum content.
• the C content is ⁇ 0.06%, preferably ⁇ 0.05%, in order not to trigger intercrystalline corrosion when soldering, that the chromium content is greater than 12%, in order to bring about rust and acid resistance, and that sufficient nickel content is provided to obtain a thermoformable material.
• Fig. 2 it is shown using the example of the nozzle 4 that the inside of the nozzle 16 is provided with a solder layer 16 made of copper.
• the material of the. Solder layer was already applied to the steel plate from which the sockets 3, 4 and 5 were deep drawn.
• the starting point here can be a board with a small thickness, for example 0.75 mm, made of copper-plated stainless steel with a copper layer thickness of 10 to 100 ⁇ m.
• the solder layer therefore extends from the free end of the socket to the side to be soldered flanges 6, 7 and 8. Soldering can be done in an oven at relatively high temperatures, for example at 1000 ° C. If a copper tube 17 is inserted into the socket 4 and soldered there, the solder layer 16 facilitates this process.
• a conventional solder can be used, for example a copper solder mixed with 15% silver, as it is sold under the trade name Silfoss 15.
• This solder melts at about 700 ° C. This temperature can be easily achieved with a welding torch at the free end of the respective nozzle. However, this temperature does not affect the heat-sensitive parts of the valve because the low thermal conductivity of the nozzle and the housing prevents this.
• the membrane box 9 provided with its filling is extremely sensitive to temperature. Their limit temperature is only 100oC
• the procedure is such that the deep-drawn housing 2 is connected to the base plate 10 and the three connecting pieces 3, 4 and 5 by soldering. Then the internals are introduced into the valve housing 2 and finally the membrane box 9 is completed by fitting the membrane and the cover 12 connected to the sensor 14 via the capillary tube 13. The heat-sensitive filler is then filled into the sensor system.
• the valve is now ready for use. It is connected in place to the connecting pipes 17 by inserting them into the connecting pieces or by pushing them onto the connecting pipes and finally fixing them to them by soldering.
• the internals can also be inserted into the housing 2 from below.
• the nozzle 3 is then only attached to the housing 2. If the internals are sensitive to heat, the last part to be attached can also be fastened by a welding process that is less heat-intensive than a soldering process, for example by laser welding.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Valve Housings (AREA)
• Magnetically Actuated Valves (AREA)
• Temperature-Responsive Valves (AREA)
• Lift Valve (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
• Details Of Valves (AREA)

Applications Claiming Priority (3)

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• 1994
  • 1994-08-22 EP EP94925359A patent/EP0715553B1/fr not_active Expired - Lifetime
  • 1994-08-22 DE DE59402678T patent/DE59402678D1/de not_active Expired - Fee Related
  • 1994-08-22 AU AU75308/94A patent/AU7530894A/en not_active Abandoned
  • 1994-08-22 CN CN94193174A patent/CN1055647C/zh not_active Expired - Fee Related
  • 1994-08-22 ES ES94925359T patent/ES2101562T3/es not_active Expired - Lifetime
  • 1994-08-22 WO PCT/DK1994/000314 patent/WO1995005908A1/fr active IP Right Grant
  • 1994-08-22 JP JP7507274A patent/JP2908565B2/ja not_active Expired - Fee Related
  • 1994-08-22 US US08/596,256 patent/US5810332A/en not_active Expired - Fee Related
  • 1994-08-22 DK DK94925359.5T patent/DK715553T1/da unknown
  • 1994-08-22 DE DE4429682A patent/DE4429682A1/de not_active Withdrawn
  • 1994-08-22 AT AT94925359T patent/ATE152648T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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