US2118613A - Vacuum-tight joint for electrode lead-ins - Google Patents

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May 24, 1938. u. LAMM VACUUM TIGHT JOINT FOR ELECTRODE LEAD-INS Filed Feb. 20, 1936 In yen for Patented May 24,1938

UNITED STATES VACUUM-TIGHT JOINT FOR ELECTRODE LEAD-INS Uno Lamm, Ludvika, Sweden, assignor to Allmi'mna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Application February 20, 1936, Serial No. 64,893 In Sweden February 27, 1935 3 Claims.

In ionic valves with liquid cathode which in practice must be placed at the bottom of the valve vessel, it has been found suitable for several reasons to introduce the conductors leading to all or some of the other electrodes, as the main anodes, exciting anodes and igniting anode, through the bottom of the vessel. It will hereby for instance be possible to assemble all the delicate parts of the apparatus on a single supporting member, on which they may readily be inspected at the very instant before the closing and subsequent evacuation of the vessel. The said arrangement is also advantageous from an electromagnetic point of view, for instance by reason 16 of the comparatively small self-inductance of the circuits.

It can, however, not be avoided that the electrodes introduced through the bottom offer somewhat greater difliculties as regards the vacuum tight joints than such electrodes introduced through the top. For the latter, as is well-known, mercury sealed joints are often employed, the characteristic feature of said joints being that a column of mercury is placed outside a solid packing and serves not only to complete but also to check the vacuum tightness, a lack of such a tightness being immediately revealed by mercury leaking into the vacuum vessel. Such joints are very suitable for electrodes introduced through the top where outside is equivalent to above, but

they cannot be simply applied to electrodes introduced to the bottom where outside means below. According to the present invention, however, the dimculty is solved in such a way that the inner one of two parts intended to form a tight joint against each other is provided with a flange having an annular groove on its upper side, said groove embracing partly the outer one of the two said parts so that the space therebetween can be filled by a sealing liquid, for instance mercury.

A form of the invention is illustrated in the accompanying drawing, which shows in a vertical section the two vacuum tight joints between an anode conductor, entering through the bottom of a valve vessel, and the surrounding insulator and between the latter and the surrounding bottom of the vessel.

l is the anode conductor (anode bolt), 2 the insulator bushing and 3 the surrounding bottom of the vessel. To the lower end of the anode bolt I, there is welded the flange 4, which has on its upper side an annular groove surrounding the bolt. The innermost portion of this groove is preferably plane at the bottom, and a tight joint is made between this plane portion and a correspondingly plane, preferably ground portion of the insulator by means of a packing 5. Outside the latter, the space between the flange 4 and the insulator 2 is filled with a suitable sealing liquid, for instance mercury, and outside the lat- 5 ter there is another packing 6 for preventing a spilling or an evaporation of the liquid.

In order to form a tight joint against the bottom 3 of the vessel, the insulator 2 is in its turn provided with a flange l, which forms on its upper 10 side an annular groove, into which a ring 8 welded to the bottom 3 engages. The solid packing 8 between this ring and the insulator 2, which forms the principal vacuum tight joint, lies in this form considerably above the lowest portion 15 of the annular groove and also above the highest portion of the flange 1, but by reason of the vacuum on the inside, the interspace can be kept filled with sealing liquid without the latter having any tendency to flow out over the flange I. The an advantage of placing the said joint surface on a. high level is among others that a plane grinding thereof is facilitated. For additional safety,

a packing i0 is also here placed outside the sealing liquid.

The drawing also shows a grid conductor introduced through the insulator 2. The said conductor consists of a vertical portion I I and a portion l2 inclined upwards and outwards, said two portions being in a conducting connection with each 30 other by at least the lower portion of the former and the inner portion of the latter being surrounded by mercury in the space l3. The outer portion of the inclined conductor is filled with cement l4, and the sealing is completed by the 35 mercury.

I claim as my invention:-

1. In a joint for an ionic valve, a metal vessel,

8. bolt-shaped anode conductor penetrating through the bottom of said vessel, an insulator 40 surrounding a part of said conductor, a flange integral with the lower portion of said conductor and forming together therewith an upwardly open annular groove for embracing a correspondingly shaped convex portion at the bottom of said insu- 45 lator, a packing between said insulator and said flange, and a sealing liquid filling the free space of said annular groove outside said packing.

2. In a joint for an ionic valve, :3. metal vessel, an electrode conductor penetrating through the 50 bottom of said vessel, an insulator surrounding a part of said conductor, an upwardly open annular groove formed in the outer portion of said insulator, an annular ridge on the base of said vessel engaging said groove, a vacuum-tight joint pro- 55 vided between said insulator and said vessel and located above said groove and closer to said conductor, and a sealing liquid filling the free space of said groove.

3. In a joint for an ionic valve, a metal vessel, a bolt-shaped anode conductor penetrating through the bottom of said vessel, an insulator surrounding a part of said conductor, a flange integral with the lower portion of said conductor and forming together therewith an upwardly open annular groove for embracing a correspondingly shaped portion at the bottom of said insulator, a sealing liquid filling the free space of said annular groove, and a conductor penetrating said insulator and comprising two portions meeting each other at an acute angle and a quantity of mercury engaging both said portions.

UNO LAMM.

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