US1406328A - Temperature-regulating means for filamentary electrodes - Google Patents

Description

'A. L. ATHERTON.

TEMPERATURE REGULATING MEANS FOB FILAMENTARY ELECTRODES.

APfLlc/Tlon FILED :1111.29.1911. 1,406,328, Patented Feb. 14, 1922.v

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AT'ToRNEY PATENT OFFICE.

UNITED STATES ALFRED L. ATHERTON. OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR T0 WEST- INGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

TEMPERATURE-REGULATING MEANS FOR FILAMENTARY ELECTRODB.

Specication of Letters Patent. Patented Feb. 14, 1922,

Application led January 29, 1917. Serial No. 145,239.

To aZZ lwhom it may con cem.:

Be it known that I. ALFRED L. ATHERTON, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a. new and useful Improvement in TemperaturerRegulating Means Ifor Filamentary Electrodes, of which the following is a specication.

My invention relates to heat-regulating means for tlamentary electrodes, such, for example, as the cathodes of hot-cathode convertel-s, and it has for its object to provide apparatus of the character designated whereby an electrode may be maintained at substantially a predetermined temperature, irrespective of changes in the load current flowing thereto.

In the accompanying drawings, Fig. 1 is a diagrammatic view of a converter of the hot-cathode type, together with auxiliary heating and load circuits, embodying a preferred form of my invention; and Figs. 2 to 6, inclusive` are diagrammatic views of inodifications of the system shown in Fig. 1.

It is well known that, if two electrodes be placed in proximity toeach other, one electrode being sufficiently hot to emitpelectrons and the other being comparatively cold, and an alternating electromotive force be impressed across said electrodes, current waves will flow to the hot electrode as a cathode and will not flow in the reverse direction.

T he above-noted principle has been quite widely employed in converters Afor changing alternating currents into direct currents and also for wireless detectors and other analogous uses.

In the various embodiments of this principle, the two electrodes are generally placed within a closed container and said container is either highly evacuated or is 'charged with an inert gas, such, for example,i as argon or nitrogen. The cold electrode is generally given the form of a mass of refractory material, such, for example, as tungsten or carbon, and the hot electrode is generally formed, in a filamentary shape, from a similar refractory material. The -cathode is maintained ata suitable temperature for starting and operating the device by passing heating current thereto from an auxiliary current source. i

It is obvious that, with apparatus of the character designated, if sufficient heating current from the auxiliary source is initially passed through the ilanientary electrode to start the device into operation, the subsequent iiow of load current will still further heat said flamentary electrode, leading to the danger of overheating the same. It is, therefore, desirable that the amount of auxiliary heating current be decreased with an increase in the load current so that the filament may be maintained at all times at a substantially uniform temperature, said temperature being suiiiciently high to maintain a pronounced electronic emission but not so high as to cause the ilamentary electrode to be unduly short-lived.

Apparatus to fulfil the above conditions may be developed in a great variety of different forms, as will hereinafter more fully appeal'. i

Referring to Fig. 1, a converter is shown at 7 said converter comprising a closed container 8 provided with an anode 9 and with a filamentary cathode 10. Energy for the operation of the converter 7 is supplied from any suitable source, such, for example, as a transformer 11 embodying a primary winding 12, a main secondary winding 13 and an auxiliary secondary winding 14. The three windings 12, 13 and 14 are mounted on a common core 15, the main secondary winding 13 beingin relative-ly close proximity to the primary winding 12, whereas the auxiliary secondary winding 14 is quite widely removed from said primary winding. The two treminals of the main secondary winding 13 are connected, respectively, to the anode 9 and to the cathode 1 0 through asuitable load device 16. The two terminals of the auxiliary secondary winding 13 are connected, respectively, to the two terminals of the tilamentary cathode 10.

The operation of the apparatus thus described is as follows. Upon supplyin energy to the primary winding 12, an e ectromotive' force is developed in the auxiliary secondary winding 14 which causes current t0 flow through the ilamentary cathode 10, raising the latter to an electron-emitting temperature. When this condition is reached, alternate half waves from the main secondary winding 13 flow from the anode 9 to the cathode 10 and back through the load, establishing the load current of the device.

VThe load current would tend to still further heat the cathode were it not for the fol- A tween the primary winding 12 and the secondary winding 13. The leakage flux is subtracted from the flux formerly traversing the auxiliary secondary winding 14, and the electromotive force produced in said auxiliary secondary winding is, therefore, decreased, reducingl the iiow of auxiliary heating current to the filament. 10.

With a decrease in the load current, the converse action takes place. The reduction in the magnetomotive force of the secondary winding 13 permits an increase in the fiux traversing the auxiliary secondary winding 14 and, therefore, increases the heating current supplied to the cathode 10.

Referring to Fig. `2 for a modified form of my invention, I show a converter 7, as before, deriving its energy from a transformer 11 provided with windings as described except that the two secondary windings may have an equally close relation to the primary winding. The filamentary cathode 10 may be energized from the secondary winding 14 by losing a suitable switch 17 in its upper position.

An auxiliary transformer 18, similar to the ordinary constant-current transformer, is also'provided for the energization of the lamentary cathode 10. Said transformer comprises a fixed primary winding 19 which is inserted in the vload circuit of the device and a movable secondary member 20 which is counter-weighted, as indicated. The counter-weighting system is such that the device has an inverse ratio, that is to say., an inc rease in the primary current causes such repulsion of the secondary winding as to actually decrease the secondary circuit, as distinguished from the ordinary constant-cnrrent transformer wherein the secondary current remains substantially constant over l wide changes in the primary current.

Having initiated operation in the apparatus of Fig. 2 by the closure of the switch 17 in its upper position, said switch is thrown to its lower osition, whereupon the filament 10 is trans erred from the secondary winding 14 of the main transformer to the secondary winding 20 of the auxiliary transformer and thereafter, so long as the apparatus remains in operation, the effect of the auxiliary transformer 18 is to maintain substantially uniform heat in the filament 10, irrespective of changes in the load current. Referring to the form of my invention shown in Fig. 3, the main parts of the system are as before, and an auxiliary current transformer 21 is provided in addition. The primary windingof said auxiliary transformer is connected in the load circuit and the secondary winding thereof is connected in the auxiliary heating circuit so that its electromotive force opposes that of the secondary winding 14. Under these conditions, the effect of the'transformer 21 is negligible until the flow of load current is initiated, whereupon an electromotive force is produced in the secondary winding thereof which is proportional to the load currentV and, therefore, tends to neutralize the electromotive force of the winding 14 and to reduce the heating current with an increase in the load current.

In the form of my invention shown in F ig. 4, the filamentary cathode is shown deriving its heating current from an auxiliary source -of direct current 22, as is frequently the case. Said auxiliary heating current traverses an adjustable resistor 23 which is under the control of a solenoid 24 or other electromotor device. The arrangement is such that, when no load current is flowing, the effective value of the resistor 23 is a minimum, permitting the fiow of a maximum heating current. As the load current increases, more and more of the resistor 23 is inserted in circuit, and the heating current derived from the battery 22f is reduced in amount, resulting in the desi-red maintenance of substantially uniform temperature at the cathode 10. If an alternating source be employed for the heating current, such, for example, as an auxiliary secondary Winding on the supply transformer, the load` responsive regulating device would preferably take the form of an adjustable reactor rather than the form of an adjustable resistor.

Thermostatic means may be employed, if necessary in order to achieve the desired end. A system of this type is shown in Fig. 5 wherein a thermostatic device 26 is mounted in proximity to the container 8 of a converter 7, said thermostat being preferably mounted adjacent to the cathode 10. A'heating coil 27 surrounds the thermostat 26 and is inserted in a portion of the circuit carrying only load current. A contact member 28 is so mounted that the thermostatic member 26 makes contact therewith when cold. A resistor 29 is normally connected in the circuit of the circuit of the auxiliary heating current so -as to be in series with the cathode 10. In operation, at starting, the thermostatic member 26 is cold and rests against the contact member 28, short circuiting the resistor 29 and permitting the fiow of a large heating current tothe cathode 10. When the thermostat 26 is heated by the joint action of the cathode 10 and of the heating coil 27, contact is broken with the member 28, and the heating current is forced to traverse the resistor 29, thus being radically diminished in amount. Obviously, the thermostat 26 may be caused to depend entirely upon either the container 8 or upon the heating coil 27 as a heating source.

In the form of my invention shown in Fig. 6, a resistor 30 is included in the load circuit and mounted in close proximity to a resistor 31 mounted in the auxiliary heating circuit. The resistor 30 is so proportioned that it varies in temperature with changes in the load current. The resistor 31 is a conductor of the first class and is so proportioned that it is not heated to any great extent by the flow of heating current therethrough. Thus, at the start, the auxiliary heating current vtraverses the resistor 31 with but little op osition because of the resistance thereof. ith the initiation of load current, the resistor 30 becomes hot and transmits heat to the resistor 31 in such amount as to radically increase the resistance thereof, thus cutting down the amount of auxiliary heating current.

It is obvious that my invention `is susceptible of still further changes and alterations without departing from the spirit thereof Y and elements shown in certain figures might equally well be em loyed in systems of certain other of the gures. Furthermore, it is obvious, for example, that, instead of introducing the 4resistor 29 in series with the filament 10 in the system of Fig. 5, the thermostat 26 might be employed to close a shunt path around said filament, but changes of this character come within the province of the skilled electrician and do not cause systems embodying the same to -be patentably distinct from each other.

While I have shown my invention in a plurality of forms, it is not so limited but is susceptible of various minor changes and modifications Without departing from the spirit thereof and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or asare indicated in the appended claims.

I claim as my invention: y

1. The method of operating a filamentary space-current device, consisting in causing a heating current and a load current to pass through the filament and causin the heating current to decrease when the oad current increases, and vice versa, in such manner as to maintain the filament temperature substantially constant.

2. The combination with an electric apparatus embodying a closed tube provided with an anode and a filamentary cathode, of

means for assing a heating current through said catho e, means for passing a load current between said electrodes, and control means for automatically decreasing said heating current in response to an increase in said load current, whereby said filamentary cathode is maintained at substantially a uniform temperature.

3. The combination with an electric apparatus embodying a closed tube provided with an .anode Vand a filamentary cathode, of means for assing a heating current through said catho e, means for passing a load current between said electrodes, and a currentresponsive device subject to the action of the load current and operative to inversely adjust the amount of said heating current.

4. The combination with an electric apparatus embodying a closed tube provided with an anode and a iilamentary cathode, of means for assing a heating current through said catho e, means for passing a load current between said electrodes, and a currentresponsive device subject to the action of the load current and operative to decrease said heating current with an increase in said load current and vice versa.

5. The combination with an electric apparatus embodyin a filamentary electrode, of means for feedln both a load current and an auxiliary heating current to said filament and automatic means for adjusting said heating current in an inverse relation with respect to said load current.

6. The combination with an electric apparatus embodying a closed tube provided with an anode and a filamentary cathode, of means for passing a heating current through said cathode, means for passing a load current between said electrodes, said filamentary cathode being heated both by said heating current and by said load current, and means controlled by said load current and automatically operative to regulate said heating current so as to maintain said filamentary cathodeat a constant temperature.

7. The method of operating a lamentary rectifier consistino in passing a heating current and a loadJ current through the filament and magnetically controlling the relative amounts of said currents to effect an increase in one as the other decreases and vice versa.

In testimony whereof, I have ,hereunto subscribed my name this 20th day of J anuary 1917.

ALFRED L. ATHERTON.

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