US2116709A - Electrical switch of the fluid flow type - Google Patents

Description

May 10, 1938. M. NIPPOLD ELECTRICAL SWITCH OF THE FLUID FLOW TYPE Filed June 18, 1937 2 Sheets-Sheet l Fig-2a INVENTOR Max Nippold X 21 A ORNEY Fig. 2

May 10, M N|PPOLD ELECTRICAL SWITCH OF THE FLUI D FLOW TYPE Filed June 18,1937, 2 Sheets-Sheet 2 INVENTOR Max Ni ai/oold #aag". I

A TORNEY Patented May 10, 1938 UNITED STATES PATENT OFFICE nmc'rmcan swrrcn or was room now I mm tion of New York Application June 18, 1931, Serial No. 148,996 In Germany June 24, 1936 1 Claim. (cl. zoo-152) The present invention relates to electrical switches of the fluid flow type, and especially to switches of this type having asealed envelope which consists almost exclusively of metal.

A particular object of the invention is to provide an improved switch of the fluidflow type. Another object of the invention is to simplify the construction of such switches. Still other objects and advantages of my invention will appear from the following detailed specification or from an inspection of the accompanying drawings.

' The invention consists in the new and novel switch structure, as hereinafter set forth and claimed.

The somewhat fragile nature of the glass envelopes of the mercury switches which are now in extensive use has led to the development of switches in which metal is substituted to a large extent .for these envelopes, switches it ,is, of course, still necessary to retain suficient glass to insulate the separate contacts of theswitch. As heretofore developed this has resulted in a seal of comparatively large diameter. I have now discovered that by a novel structure of my invention these switches may be made of substantially all metal, with only the use of a small glass head as insulation. This facilitates the manufacture of these switches in very small sizes, as compared to prior switches, and also affords numerous other advantages.

The invention is illustrated by means of several examples. in the accompanying drawings, in which -Figure 1 shows the the new switch,

Figures 2 and 2a show the introduction of the electrode through a material with coemcient of expansion which approximately agrees with that o l Figures 3 and 4 show'these switches in closed and open circuit position, respectively,

Figure 5 shows a be her shaped switch with welded cover,

Figure 6 shows a tube welded cover, r Figure 7 shows a tube with constructions ready to be cut apart to form switch bodies,

shaped switch with "Figure 8 shows a switch whose inlead is in- .serted insulated through the constriction at one end, while the other constriction iswelded shut,

and

Figure 9 shows a switch with an enclosed steel sphere which is adapted for magnetic operation. According to the invention as shown in Figure 1,-fa projection b is provided in a closed metal In each of these ring h and theplatinum coating i applied thereto,

tube a. In this metal tube, which is made of a material which is not attacked by the liquid, e. g. steel where mercury is used as the switch liquid, there is placed the switch liquid c. As the switch liquid mercury, or, where desired, as where the 5 switch may encounter high ambient temperatures, potassium-sodium, gallium etc. is used. The metal tube (4 serves as one contact, while the other contact is introduced as an inlead wire d through a suitable insulatlng'bead e of glass or the like. So-that the switch liquid will not be contaminated or oxidized, a vacuum is produced in the tube, or preferably the tube is filled with a protective gas, such as nitrogen, hydrogen, or the like, at any desired-pressure, up to several atmospheres. In general, however, normal atmospheric pressure is chosen. The evacuation hole I at the end of the tube is closed after this process, for instance by scaling in a pin g or afilxing a sphere.

The current capacity of sucha switch is determined by the thickness and resistance of the inlead d, the quantity of the liquid c and the contact resistance between the metal and the liquid. As this contact resistance, suchas that between iron and mercury, for instance, is extremely high, a coating of platinum is preferably provided on the end of the inlead d and on the tube (1 around the glass bead e. Thiscoating is produced in any suitable manner, as by melting it on or by chemical or electrolytlcal means.

The voltage which the switch is capable of handling is determined by the distance between simplest possible form .of

the'inlead d and the metal casing, i. e. by the size of the glass bead c. This voltage capacity is, of course, easily altered by varying this distance. Besides this glass insert, according to the invention an insert of porcelain or micalex can also beused, which is particularly suitable for the switching of high frequency currents. 40

In the foregoing it is assumed that the switchenvelope a is made of a metal, such as a special iron alloy (e. g. fernico), which has practically the same coeflicient of expansion as glass. These alloys, however, are relatively expensive, and hence the insertion of inleads according to the invention is preferably accomplished by means of a ring it of this alloy which is welded into an envelope of any metal which is suitable for use with the switch'fluid, as shown in Figure 2. Or, as is shownin Figure 2a, magnified, this ring it is sealed on by an external weld. 'I'he latter method of construction has the advantage that the beaded glass inlead d can be fused to the and off positions.

after which this complete assembly is welded into the switch tube as a stopper after the switch liquid has been introduced, the tube evacuated, and the protective gas introduced. A special closing by pin or sphere is thus made unnecessary Figures 3 and 4 show such -material, and the switch liquid 0. The disc m is in some cases made of a special iron alloy or. oi steel to which glass can be directly fused. in which case, as in Figure 2, the ring-glass seal is welded on. If the glass seal is made directly on the disc m without a ring, then a filling hole must be provided, which is sealed by a sphere n.

Figure 6 shows a construction similar to that of Figure 5, in which however the envelope 1 is more tube shaped. With such a switch the switching can be accomplished by turning as well as by tilting. v

Where a very large number of these switches are desired it is convenient to provide a seamless steel tube 0 with constrictions p, as shown in Figure '7. This tube is then cut through at these constrictions and the protective gas, switch liquid, inlead with glass seal, and finally the metal ring are inserted at one end as-shown in Figure 8.

The other constriction is then sealed directly or a switch in the on by means of a sphere n or the like, with the aid of welding heat.

Figure 9 shows yet another form with bent tube 0 in which another steel sphere q is introduced.

-When the coil 1- which is placed about the middle of said tube is momentarily energized this sphere is attracted and rolls to theother end of said 'tube, whereupon the switch,- which is freely movthereof it is to be understood that it is not limited th ereto, but that various omissions, substitutions and changes, within the scope of the appended claim, may be made therein without departing from the spirit of the invention.

What I claim as new and desire to'secure by Letters Patent of the United States, is:-

A fluid flow switch comprising a metal con-' tainer containing a conducting fluid, said container being of a metal which is substantially unaflected by said fluid, an opening in said container within which is welded a ring of a diiferent metal which likewise is unaflected by said liquid and whichhas a coeflicient of expansion comparable with that of glass, a glass-beaded inlead fused into said ring, and a platinum coating on said inlead and on said ring, said liquid being suflicient to close an electrical circuit between the coated areas on said inlead and said ring.

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