US1749611A - Method of rectifying alternating currents - Google Patents

Description

March 4, 1930 F. SCHROTER METHOD OF RECTIFYING ALTERNATING CURRENTS Filed March 16' 1921 anvemtoz Mme/1 Patented Mar. 4, 1930 UNITED STATES PATENT OFFICE FRITZ SGHROTER, OF BERLIN, GERMANY, ASSIGNOR TO SAFETY CAR HEATING & LIGHTING COMPANY, A CORPORATION OF NEW JERSEY METHOD OF RECTIFYING ALTERNATING CURRENTS Application filed. March 16, 1921, Serial No.

This invention relates in general to alternating current rectifiers employing a gaseous conduction .device and relates more particularly to an improved method of rectifying alternating currents by means of gaseous discharge.

One of the objects of this invention is to provide a method of constructing a gaseous discharge alternating current rectifier of effective and reliable action and to provide a method of construction and operation of rectifiers of the above type by which certain disadvantages resulting from the absorption of the gaseous content by the material of the electrodes are avoided and by which the life of the rectifying discharge tube is greatly prolonged. Other objects will be in part'ohvious or in part pointed out hereinafter.

The invention accordinglyconsists in the features of construction. combinations of elements and sequence of steps as would be exemplified in the following description and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which are shown several of various possible embodiments of the mechanical features of this invention,

Figure 1 is a central cross section of a gaseous conduction device adapted to operate as a rectifier; and

Figure 2 is a similar central cross-sectional view of a modified form of gaseous conduction device, the latter being shown in this figure as related to an electric circuit for rec- .tifying action.

Rectifying tubes employing dissimilarly proportioned electrodes and a gaseous content composed, for example, of gases of the helium group, are found to be substantially uni-directional in their action upon an alternating current and are found to permit the passage therethrough of only those alternations which are of one polarity. Tubes of this character, however, are found to permit also the passage in a greatly decreased magnitude of those alternations of the alternating current which are of the opposite polarity and which it is desired to suppress. Such alternations of currentof opposite polarity which 452,825, and in Germany November 3, 1919.

the discharge tube is to choke off or substantially prevent the passage of, are found to exhibit a high cathode drop in potential and accordingly to cause an intense volatilization of the metal of the rectifying anode. Such a volatilization takes place in the form of small particles of the electrode material emanating from the anode in substantially all directions therefrom and into the gaseous atmosphere of the tube. The small particles of the electrode material thus emanated from the surface thereof cause an undesired absorption of the gaseous content and thus, in so affecting the gaseous content, cause a material diminution in the life and effectiveness of the rectifying tube.

It is one of the aims of this invention to avoid the detrimental effects of such absorption and in accordance with the method of this invention, the cathode is so positioned with respect to the anode that the former substantially surrounds the latter and is in substantially close proximity thereto. In the normal operation of a glow-discharge tube of this type, the temperature of the cathode 7 is relatively high as compared with temperatures existing in other parts of the tube. By reason of the relative location of the cathode with respect to the anode, the metal particles which emanate in substantially all directions in addition to normal from the individual surface elements of the anode are made to strike or impinge as completely as possible upon the heated surface or to enter the regions in immediate proximity to the cathode, whose temperature is considerably higher than that of the anode or of the particles emanating therefrom. Hence, the particles resulting from the volatilization of the anode and which absorb the gases of the atmosphere are heated by their contact with the cathode surface or by their entry into the cathode regions to the higher temperature thereof and are thus made to return or emit the gases absorbed by them. The gaseous content of the tube during its functioning is thus maintained substantially intact and no losses result therein by reason of the absorption as hereinbefore pointed out. The discharge tube is thus made capable of functioning efiiciently and substan- 1C0 tially the same number of molecules of the ing more specifically the manner in which the electrodes are mounted within the vessel 10, it will be seen that within the vessel 10 and suitably sealed to the bottom portion thereof there is a post or pedestal 13 adapted to support at its lower end, as by means of the wires 14, the one end of the electrode 11 which preferably is made of sheet metal and bent or formed into a cylindrical shape. The wires 14 are fused into the glass pedestal 13 \.25 and one of them is extended as at 15 .to the exterior of the vessel 10to form one of the conducting elements of the gaseous conduction device. At the upper end of the cylindrically shaped electrode 11 there are provided wires 16 which, like the supporting wires 14 hereinabove mentioned, are preferably welded or otherwise suitably secured to the electrode 11. The wires 16 are extended upwardl and at their ends are provided with suitablh insulating beads17 which may take the form of glass and which may be fused into the interior wall-forming parts of the vessel 10 thereby to rigidly hold the electrode 11 in position.

Extending through the glass pedestal 13 is a conductor 18 which is electrically connected at its upper end to the electrode 12 hereinbefore mentioned. The electrode 12 preferably takes the form of a heavy wire suitably sup orted upon or fused into the upper end 0 the post 13. The electrode 12 is surrounded by an insulating tube 19 spaced therefrom and this tube 19 is in turn surrounded by an insulating tube 20 also in spaced relation with the tube 19. This construction is adapted to prevent the formation of a continuous coating adjacent the electrode 12 by reason of the deposition upon the parts surrounding the electrode 12 of metal lic particles emanating from the electrodes durmg their 0 ei'ation. This construction, it may be note forms no part of this invention and as for the details thereof reference may be had to the co-pending application of Otto Schaller and Frltz Schrfiter, filed July 22, 1920, Serial No. 398,276.

In the operation of the device the electrode 12 is adapted to function as the anode and the electrode 11 is adapted to function as 65 the cathode. When connected into the circuit of an alternating current source of supply the gaseous content will become ionized and the current will flow from the anode 12 to the cathode 11, by reason of the dissimilarity of the electrodes, it being noted that the cathode 11 is of extremely large surface area relative to that of the anode 12. The current thus flowing in this direction is made possible by'reason of the large surface of the cathode 11- which may be considered as permitting the flow thereto and reception thereon of a much greater number of electrons emanating from the anode 12 than could take place in the reverse direction.

When, however, that alternation of the alternating current which it is desired to suppress becomes efl'ective upon the electrodes of the device, the effect thereof will be to make the electrode 12 act as the oathode and the electrode 11 as the anode.

Butbecause-of its relatively small active.

surface when acting normally as above described, the electrode 12 is at a relatively high temperature because of the high 'intensity of the current -flow therefrom to the cathode 11. The electrode 12 therefore, is, during the period in which it acts as a catho e, strongly inclined towards disintegration and metallic particles thereof are projected or emanated therefrom.

As has been hereinbefore noted, the particles resulting from the volatilization of the electrode abssorb the gases of the atmosphere contained within the vessel 10 and thus brin about detrimental eifects upon. the life and effectiveness of the rectifying tube. But it will be seen that the cathode 11 which during normal operation attains a relatively high temperature, substantiall entirely surrounds the anode 12 and t us intercepts the particles emanating from the anode'12. The

emanating particles which occlude the gases .in the vessel 10 are thus heated as soon-as they contact with the surface of the cathode 11 or as soon as they enter into the cathode region of a higher temperature. Such particles are thus raised. 1n temperature and 7 hence are made to return or absorbed by them.

In Fig. 2 is illustrated a modified embodiemit the gases ment of-the mechanical features of this in vention and it will be noted that the vessel 10 is provided with a post or pedestal 13 in the upper end of which is mounted the anode 12' in a manner substantially similar to that in which the anode 12 of Fig. 1 is mounted. The protective insulating tubes 19 and 20' provide intervening spaces for preventing the formation of a continuous coating by the deposition of particles emanating from the electrodes. Upon the base portion 13 of the post 13' is mounted the other electrode 11 adapted to function as the cathode, and it will be seen that it is supported thereon by means of the supporting wires 14 one of which is extended as at 15 to the interior of the vessel 10" to form an electrical connection to the exterior. The electrode 11, it will be seen, is of a general cylindrical shape and is composed of a suitable sheet metal; and it will be seen that at its upper end it is closed by the dome-like cap 11'. Also it will be noted that at the upper end it is supported by means of the supporting wires 16 and the insulating beads 17" adapted-to contact with the interior wall of the vessel 10" and adapted also to be fused thereto. Throughout the electrode 11 there are substantially uniformly distributed a plurality of openings 21.

The anode 12 is connected by means of the conducting element or wire 18 to the exterior of the vessel 10 and it will be seen that this conducting element 18* may conveniently extend to the supporting post 13. In Fig. 2' there is also diagrammatically illustrated an electric circuit in which the use of the rectifying gaseous conduction devices of either Fig. 1 or Fig. 2 is illustrated. It will be seen that the circuit comprises a source 22 of alternating current and, for the sake of illustration, it is assumed that itis desired to rectify the current therefrom into direct or unidirectional current for the purpose of charging a storage battery indicated at 23. In the same circuit is included a variable resistance 24 adapted to regulate the intensity of current flowing to the storage battery. The rectifying tube'is also connected in the circuit and it will be noted that the anode 12 and the cathode 11' are so connected therein that the current in the entire circuit can flow only in the direction of the arrow indicated at 25, this direction of flow being determined by the current flow from the anode 12 to the cathode 11.

In the operation of the rectifying device illustrated in Fig. 2, the openin s 21" permit the exterior surface of the catho e 11" to take part in the rectifying action; that is, the

openings 21 provide a path for the current flowing from the anode 12 through the openilrigs 21 to the exterior surface of the cathode The anode 12 has a great tendency to disintegrate and to give off metallic particles therefrom, much in the same manner as described in connection with the anode 12 of the device illustrated in Fig. 1. But the cathode 11 substantially entirely encloses or surrounds the anode 12*, since the domeshaped cap 11 forms with the side cylindrical walls of the cathode 11 a substantial enclosure for the anode 12. Thus the articles emanating from the anode 12" w ich, as

hereinbefore noted, tend to occlude the gasesin the vessel 10" are made to impinge upon the surface of the cathode 11' or are made to enter the region adjacent the cathode 11, whereby said particles are raised in tempertrated in Figs. ,1 and 2, thus making themhighly dissimilar with respect to the oath odes. The anodes may also, for example, be made of iron wire.

It will thus be seen that there has been provided in this invention an apparatus and method by means of which the detrimental occlusion or absorption of the gaseous content of the gaseous discharge evice is effectively prevented, and that the method and apparatus thus provided by this invention insures the presence in the discharge or rectifying device of substantially the same number of molecules of the gaseous content at all times available for ionization. The proper and desired action of the tube is thus maintained and the life thereof materially enhanced.

Since various changes might be made in the invention and in the steps thereof hereinbefore set forth, it is to be understood that all matter hereinbefore set forth is to be interpreted as illustrative and not in a limitmg sense.

I claim as my invention:

1. In rectifying tubes of the gaseous conduction type having a metallic anode and a cathode, the method of preventing the per-- manent absorption of the gaseous content cles emanated from the anode to impinge upon the surface of the cathode whereby such particles are raised in temperature and are caused to emit gases absorbed thereby. -2. In rectiqin tubes of the gaseous conduction type avmg a metallic anode and a cathode, the method of reventing the permanent absorption of e gaseous content which consists in raising the temperature of the metallic particles emanated from the surface of the anode to cause said particles to emit the gases absorbed thereby, by utilizing the heat produced at the cathode.

In testimony whereof, I have si name to this specification this 22n January, 1921.

ed my day of DR. FRITZ soHRoTER.

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