US2651737A - Ignitron - Google Patents

Description

Patented Sept. 8, 1953 IGNITRON Donald E. Marshall, Clifton, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 6, 1950, Serial No. 188,684

2 Claims.

This invention relates to vapor-electric devices such as are generally known as ignitrons.

In general, ignitrons are constructed with a, pool cathode, usually of mercury, and therefore are not capable of universal use, but must remain in a fixed position to maintain the relationship or" the pool surface constant with respect to other electrodes in the device. It therefore has not been practical to employ the usual construction or": ignitron in mobile units or under conditions involving movement disturbing to the mercury pool, such as occurs with use on water, land or air vehicles.

The invention has for its primary object, the construction of an ignitron, with a starting or control electrode, not affected by movements normally disturbing to a mercury pool.

More specifically, an object of the invention is to provide an ignitron wherein the starting or control electrode maintains a fixed relation to the cathode under all conditions of movement and in any position of the ignitron.

In detail, the invention contemplates the provision of an ignitron having a starting or control electrode and having a sponge cathode in constant fixed contact one with the other.

Other objects of the invention will appear to those skilled in. the art to which the invention appertains as the description proceeds, both by direct reference thereto and by implication from the context. J

In the accompanying drawing, one embodiment is presented as illustrative of the inventive concept, but the arbitrary selection of the particular ignitron is not to be construed as restrictlve thereto. Accordingly, it may be stated that the figure appearing in the drawing is a central sectional view of an ignitron of arbitrarily selected construction and showing my invention embodied therein.

In the specific embodiment of the invention and associated ignitron construction illustrated in the drawing, there is shown a cylindrical casing it of steel or other sturdy material having 3. bottom integral therewith and a top header l sealed at the upper rim of said casing to provide a closed envelope adapted to be evacuated.

The header provides appropriate lead-1n seals t l, it; for electrode leads l6, [1 respectively for an anode it and ignitor it) within the casing and supported from said header by said leads. The lead-in seals each include a glass or other insulating sleeve 20 by which the leads are kept electrically distinct from each other and from the casing. The anode i8 is located toward the top of the casing, well above the bottom wall l2, whereas the ignitor I9 is located below the anode and is directed toward and terminates at its bottom in the vicinity of said bottom wall. Said ignitor is shown as relatively slender and tapers downwardly, with its bottom end quite small and semi-spherical or rounded. Said ignitor may be composed of materials as used for ignitors of the prior art, or may be of such other material or materials adapting it more especially to the present invention.

In said casing til, at the bottom thereof, I provide a cake or body 2| composed of a porous material which has the property of a sponge absorptive and/or adsorptive to mercury or other reconstructing liquid cathode material, and while I prefer to use metal for the purpose, I do not confine myself thereto. Sintered iron is an acceptable material for the said sponge. Sintered molybdenum likewise makes an excellent porous body for the purpose and is in some respects superior to sintered iron. The cake or sponge 2! is flat and relatively thin, and preferably fills the bottom of the envelope to the periphery of said cylindrical casing 10, and is suitably held in place on the bottom wall l2 by frictional contact with the cylindrical casing, or otherwise.

Mercury or other reconstructing liquid cathode material is applied to the sponge body 2| to the extent that said body will absorb the mercury or the like without any excess remaining on the surface. One manner of thus charging the sponge body with mercury is to cleanse the sponge material until sufliciently clean to be wetted by mercury and then apply an excessive amount of mercury in the casing, whereupon the sponge will immediately fill with mercury, after which the free mercury which is not absorbed into the sponge can be poured off. The sponge body M with the absorbed mercury constitutes the cathode of the ignitron.

The aforementioned rounded lower end of the ignitor l9 rests upon the upper surface of the sponge body it in constant contact therewith, and as one means for maintaining such contact without detriment to the lead-in seal 15, the lead-in H for the ignitor, between the seal and the ignitor, is shown looped, and the loop 22 possesses adequate resiliency, supplemented by the weight of the ignitor, to accomplish the purpose. The ignitor projects, from its substantially point contact on the sponge body, at right angles to said body and longitudinally of the casing.

Unexpectedly, it was discovered that an ignitron having a sintered metal, mercury-containing sponge cathode as above described, with an ignitor resting thereon with substantially point contact therewith, required considerably less power to fire the ignitor in use than is required in ignitrons utilizing a pool of mercury with the ignitor dipping therein. Due to this advantage alone, the ignitron thus constructed is superior to the usual mercury-pool ignitrons, and has the further advantage that the ignitron is adapted for use where pool-disturbing movements are involved, as on shipboard, in train service, or with mobile units.

I claim:

1. An ignitron comprising a sealed casing having an anode therein, a sponge body fixed in said casing and having a face directed toward and spaced from said anode, an elongated ignitor in said casing between said anode and said face of the sponge body and axially perpendicular to said face, said ignitor having an end thereof in contact with said face of said sponge body and always in contact with the same spot of said surface, a lead-in connection insulated from said casing and carrying said ignitor at the inner end of said lead-in connection, resilient means included as part of said lead-in connection and applying force longitudinally of said ignitor and holding the end of said ignitor permanently in tight perpendicular engagement with the said spot of the surface of said cathode and thereby maintaining a substantially constant firing characteristic for the ignitron, and reconstructive cathode material in said sponge body.

2. An ignitron comprising a sealed casing having an anode therein depending toward the bottom of said casing, a sponge body fixed in the bottom part of said casing and filling said bottom part to the side Walls of the casing so as to receive directly on the upper face of said sponge body for adsorption thereinto all reconstructive cathode material gravitating down the side walls of the casing to said upper face, an elongated ignitor in said casing between said anode and said face of the sponge body and axially perpendicular to said face, said ignitor having an end thereof in contact with said face of said sponge body and always in contact with the same spot of said surface, a lead-in connection insulated from said casing and carrying said ignitor at the inner end of said lead-in connection, resilient means included as part of said lead-in connection and applying force longitudinally of said ignitor and holding the end of said ignitor permanently in tight perpendicular engagement with the said spot of the surface of said cathode and thereby maintaining a substantially constant firing characteristic for the ignitron, and reconstructive cathode material in said sponge body.

DONALD E. MARSHALL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,128,861 Tonks Aug. 30, 1938 2,169,032 Slepian Aug. 8, 1939 2,447,637 Colaiaco Aug. 24, 1948 2,468,037 Clark Apr. 26, 1949 2,490,087 Pakala Dec. 6, 1949

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