US2071748A - Rectifier tube - Google Patents

Description

A. HUND RECTIFIER TUBE Feb. 23, 1937.

INVENTOR August Hmul ATTORNEY Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE.

RECTIFIER TUBE August Hund, West Orange, N. J., assignor to Wired Radio, Inc., New York, N. Y., a corporation of Delaware Application March 8, 1934, Serial No. 714,662

8 Claims.

, handling large currents even at low voltages.

Another object of my invention comprises providing a self-starting glow arc tube requiring no external or auxiliary means for preventing cessation of operation during alternate half-cycles of the alternating current supply.

Another object comprises providing a recti- -fier having combined arc and glow characteristics for maintaining a continuous state of ionization during rectification operations.

A further object comprises providing a rectifier tube having a cathode surface which is highly positive in the electromotive series of metals for activation in an ionizing gas for rectification purposes.

A still further object consists in providing a rectifier tube having segregation means for maintaining a glow arc ionization chamber.

These and other objects will be apparent from the following, reference being had to the accompanying drawing which forms a part of this specification and in which like reference numerals designate corresponding parts throughout.

Fig. 1 of the drawing is a transverse sectional view of one embodiment of the rectifier construction of my invention;

. Fig. 2 is a horizontal sectional along the line 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view of another form of the rectifier construction of my invention;

Fig. 4 is a horizontal sectional view taken along the line 4 -4 of Fig. 3;

Fig. 5 is a fragmentary perspective sectional view of another form of cathode structure such as may be used with either of the forms of rectifier tubes shown in Figs. 1 and 3; and

Fig. 6 is a diagrammatic representation of the rectifier tube of my invention operatively connected in a utilization circuit.

My invention contemplates providing a rectifier having a low internal voltage drop for the emcient rectification of alternating currents, and which requires no auxiliary electrodes or external circuit components, such as choke coils, for starting or maintaining operation during alternate half-cyles of the current supply. To accomplish this, I provide electrodes in an atview taken tenuated atmosphere of ionization gas, one of the electrodes being of a metal highly positive in the electromotive series of metals, such as sodium. The pressure of the ionization gas is adjusted so that a glow is maintained between the elec- 5 trodes continuously when the alternating potential is applied to the electrodes. That is, during both half-cycles of the alternating voltage, the

glow is maintained. This glow ionizes the area between the electrodes suificiently to facilitate 10 the ignition of a rectification are at the proper time, between alternate half-cycles of the current supply when rectification normally takes place. This system of operation makes it possible to start the useful glow are at the proper time so 15 that it is unnecessary to provide lagging means" in an external circuit for maintaining the rectification operation. An additional advantage of such an arrangement is the appreciable limitation of any inverse current fiow of the rectifier which may exist.

Referring to the drawing in detail, and particularly to Fig. 1, there is provided an envelope I composed of suitable refractive material which may be chosen with a view to being resistive to alkali metal vapors in the event that such vapors should reach it. This envelope I is joined by an appropriate seal with a metal cylindrical base member 2 which may be composed of copper. The cylindrical base member 2 has an inner cylindrical metallic member 3 having an upper annular flange portion 4. This upper annular flange portion 4 has a center hole through which an electrode 6 depends from a seal 1 at the upper extremity of envelope l. The electrode 6 may 35 be composed of. tungsten or other suitable metal. This electrode 6 extends to within a short distance from the bottom 8 of the base member 2 which is covered with a metal highly positive in the electro-motive series of metal. For example, the bottom 8 of base member 2 may be provided with an alkali metal such as sodium.

Except for a small end portion adjacent the bottom 8, the entire electrode 6 within the tube structure is covered by an external hollow sheath [0 composed of suitable refractive material and afiixed to theseal 1. This sheath is not in intimate contact with the electrode 6 but is spaced therefrom and has a closing end portion ll having a clearance hole through which the electrode 6 extends. It will be seen that the annular flange 4 provides a form of compartment within which the glow are and rectification operations take place. For segregation purposes, there is provided a member l2 encircling the sheath Ill and provided with a skirt IS with a feathered edge which rests upon the sloping surface of the flange 4 and, in effect, forms a closure for the ionization chamber.

Within the tube structure as a whole, I provide an attenuated atmosphere of an ionization gas. For example, in one tube I provide an atmosphere of argon at a pressure of 3 mm. of mercury.

Base 2 with the alkali metal deposit therein forms the cathode of the rectifier tube shown in Fig. 1, while the rod 6 forms the anode, as far as the rectification operation is concerned. When an alternating current source is connected to the electrode 6 and base 2, the pressure of the ionization gas Within the tube structure is such that a glow is initiated between the electrode 6 and the alkali metal deposit on the bottom 8 of base member 2. This glow is maintained continuously, and instantly initiates the rectification glow arc during alternate half-cycles of the current supply. It will be understood that the representation of Fig. 1 is essentially a power tube for handling large currents and that the metal electrode base member 2 may be provided with suitable cooling arrangements such as air fins or a fluid cooling medium. Further, in such power tubes, it will be understood that all-metallic containers and associated pumps may be employed when desired.

Fig. 3 shows another embodiment of the construction of my rectifier tube in somewhat different form. In the embodiment shown in Fig. 3 there is provided an envelope which encloses 35 the entire rectifier structure. The envelope 2!) is composed of a vitreous material such as that used in the envelope 1. The bottom of the envelope 20 is provided with a seal 2| through which a rod-like electrode 22 extends. The rod-like electrode 22 has an upper flattened portion to which is afiixed a cup-like cylindrical member 23 having an upper annular flange portion 24 simi lar to the corresponding structure shown in Fig. 1. The cylindrical member 23 may be composed of a suitable metal such as copper and forms the ionization and glow arc chamber of the structure of Fig. 3. Through a hole in the flange member 24, another rod-like electrode 2! depends from a seal 28 in the upper extremity of the envelope 5 20. The rod 21 extends adjacent the bottom 28 of the cup-like member 23 and is provided with an external sheath 29 depending from the seal 28, similar to the corresponding structure of Fig.

1. The bottom 28 of the cup-like member 23 is 55 provided with an alkali metal similar to the structure of. Fig. 1, and an attenuated atmosphere of ionizing gas is provided within the entire tube structure.

segregating members are provided in the form of a cylindrical member 30 surrounding the sheath 29 and another cylindrical member 32 surrounding the member 30 as well as the sheath 29. Both of these cylindrical members 30 and 32 are provided with feathered annular skirts 3| and 33, respectively, which individually rest upon the sloping annular flange 24 for providing a form of closure for the ionization chamber within the cup-like member 23. It will be understood that the closure members have a certain latitude of movement.

Fig. 5 represents a further modification to the rectifier of my invention and shows a form of cathode structure which may be used in either of the types of tubes shown in Figs. 1 and 3. Reierring to Fig. 5, the base member 2 is provided with an inner cylindrical member 35 concentrically positioned with respect to the base member 2 and provided with an upper sloping flange portion 31. The flange portion 31 is similar to the corresponding flange portion in Fig. l and may be provided with the same segregating members as provided in Fig. 1 or Fig. 3. This flange portion 31 encircles the same form of electrode 6 which extends adjacent a grid 36 in the bottom of the base member 2. The grid 36 is composed of material similar to the base member 2, such as copper, and is provided with a multiplicity of adjacent perforations forming a gridlike structure. The perforations or open part of the grid 36 are filled with the alkali metal deposit, such as sodium. The inner wall of the member 35 is roughened so as to better retain sodium from the grid 36. This roughened surface may be accomplished by a fine thread or other suitable means.

In a further development of the rectifier tube of my invention, I may provide, within the ionization or glow arc chamber, a deposit of finely divided metal in conjunction with the deposit of alkali metal. This finely divided metal is of heavier material than the alkali metal and has preferably a higher melting point than that of the active alkali metal and may be copper or iron powder.

Fig. 6 shows how the rectifier construction of my invention may be utilized for operation. The diagrammatically represented tube 40 may have its anode 4| and cathode 42 connected in circuit through a load 43 and a device 44 to the secondary 45 of a transformer connected with a source of alternating current 46. The load 43 is here shown as a shunt wound motor useful for producing variable speed rotation of substantially uniform torque. The device 44 may be a choke coil, a resistance or both. The rectifier tube of my invention is well adapted for such use as well as many other systems where simple and efficient means are required for converting alternating current into a direct current supply.

The present invention is not to be confused with a glow rectifier since a glow rectifier would, even with an alkali metal coating on the cathode, produce an internal voltage drop of 80 volts at best, which, for instance, for 5 amperes of rectified current would correspond to a tube loss of 80 X 5:400 watts In the glow arc rectifier of my invention it is the arc discharge which is utilized during the rectifying half-cycle and the drop can be as low as 3 volts which would correspond to a tube loss of only 3 5=15 watts in the above example. This illustrates the inherent advantage of my invention and the distinction over the glow type rectifier and the glow type rectifier with alkali coating.

A further feature of my invention is that the alkali metal used as the cathode has a further function in serving as a getter and keeper" for producing and maintaining a purified gaseous atmosphere within the tube envelope. That is, the alkali metal actively combines with any water vapor, oxygen, etc., which may be present to produce inert compounds in minute traces within the tube, thereby attaining a pure state for the ionization gas within the tube.

Although I have shown a preferred form of my rectifier construction it will be understood, of-

course, that many changes can be made therein without departing from the intended scope of my invention. I do not, therefore, desire to limit myself to the foregoing except insofar as may be pointed out in the appended claims.

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

1. A rectifier comprising a gas-tight envelope composed partially of metal and partially of a vitreous material and containing an ionization gas, partition .means dividing said envelope into two compartments, an aperture in said partitioning means, an alkali metal maintained within one of said compartments and constituting a cathode, and an anode extending from the vitreous portion of said envelope, passing through said aperture in said partitioning means and terminating with an extremity thereof adjacent said alkali metal.

2. A rectifier comprising a gas-tight envelope composed partially of metal and partially of a vitreous material and containing n ionization gas, a partitioning member located in the metal portion of said envelope and providing a chamber therein, an aperture in said partitioning member, an alkali metal maintained within said chamber and constituting a cathode, an anode extending from the vitreous portion of said envelope, passing through said aperture in said partitioning member and terminating with an extremity thereof adjacent said alkali metal.

3. A rectifier comprising a gas-tight envelope composed partially of metal and partially of a vitreous material and containing an ionization gas, a partitioning member located in the metal portion of said envelope and providing a chamber therein, an aperture in said partitioning member, an alkali metal maintained within said chamber and constituting a cathode, the inner walls of said chamber for at least that portion thereof between said partitioning member and said alkali metal being roughened and an anode extending from the vitreous portion of said envelope, passing through said aperture in said partitioning member and terminating with an extremity thereof adjacent said alkali metal.

4. A rectifier comprising, an envelope containing an ionization gas, partition means dividing said envelope into two compartments, an aperture in said partition means, an alkali metal and a quantity of finely divided metal having a melting point higher than said alkali metal maintained within one of said compartments and constituting a cathode, and an anode extending through said aperture in said partitioning means and terminating with an extremity thereof adjacent said alkali metal and said finely divided metal.

5. A rectifier comprising, a gas-tight envelope composed partially of metal and partially of a vitreous material and containing an ionization gas, partition means dividing said envelope into two compartments, an aperture in said partitioning means, an alkali metal and a quantity of finely divided metal having a melting point higher than said alkali metal maintained within one of said compartments and constituting a cathode, and an anode extending from the vitreous portion of said envelope, passing through said aperture in said partitioning means and terminating with an extremity thereof adjacent said alkali meta and said finely divided metal.

6. A rectifier comprising, an envelope containing an ionization gas, a metallic chamber in said envelope, an alkali metal maintained in said chamber and constituting a cathode, said chamber having therein an aperture provided with a tapered fiange, an anode extending through said aperture and positioned with an extremity thereof adjacent said alkali metal, a sleeve of suitable refractory material enclosing all of that portion of said anode within said envelope, except the extremity thereof near said cathode, and a flanged sleeve on said anode refractory sleeve and maintained in contact with the tapered flange of said aperture for, in cooperation with said anode sleeve, substantially closing the aperture in said chamber.

7. A rectifier comprising, an envelope containing an ionization gas, a metallic chamber in said envelope, an alkali metal maintained in said chamber and constituting a cathode, said chamber having an aperture therein, the surface of the inner walls of said chamber extending between the alkali metal and the portion containing said aperture being roughened, an anode extending through said aperture and positioned with an extremity thereof adjacent said alkali metal, a sleeve of suitable refractory material enclosing all of that portion of said anode within said envelope except the extremity thereof near said cathode and a flanged sleeve on said anode refractory sleeve and cooperating with said anode sleeve in substantially closing the aperture in said chamber.

8. A rectifier comprising, an envelope containing an ionization gas, a metallic chamber in said envelope, an alkali metal and a quantity of finely divided metal having a higher melting point than said alkali metal maintained in said chamber and constituting a cathode, said chamber having an aperture therein, an anode extending through said aperture and positioned with an extremity thereof adjacent said alkali metal and said finely divided metal, a sleeve of suitable refractory material enclosing all that portion of said anode within said envelope except the extremity thereof near said cathode, and a flanged sleeve on said anode refractory sleeve and cooperating with said anode sleeve in substantially closing the aperture in said chamber.

AUGUST HUND.

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