US2140372A - Electrode feed mechanism for searchlights - Google Patents

Description

Dec. 13, 1938. w. A. PENNOW 7 2,140,372

ELECTRODE FEED MECHANISM FOR SEARCHLIGHTS Filed Nov. 27, 1934 2 Sheets-Sheet l 3 6 Vb/fag-e Cal/ WITNESSES: INVENTOR J' MY/As fl/ ennow.

Dec. 13,1938. w. A. PENNOW 2,140,372

ELECTRODE FEED MECHANISM FOR SEARCHLIGHTS Filed Nov. 27, 1934 2. Sheets-Sheet 2 L? 2 I /9 2 7 'IJ'HIIIII VIA l5 /8 24 Wm //M\\\ 26 25 Phofo 53 I/b/Iaye (Te/K I I T 35 WITNESSES: INVENTOR fdw I /4/////5 /7/%fl/70W Patented Dec. 13, 1938 UNITED STATES ELECTRODE FEED MECHANISM FOR SEARCHLIGHTS Willis A. Pennow, Lakewood, Ohio, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 27, 1934, Serial No.

3 Claims.

My invention relates, generally, to are controlling devices and more particularly, to devices for controlling the feeding operation of an electrode which may be used in searchlights and are lighting devices in general.

Heretofore, it has been the practice to control the feeding operation of positive electrodes in high-intensity arc searchlights by means of feed mechanisms in the form of ratchet devices and.

the like, the functioning of which are controlled by thermostatic devices responsive to radiant energy produced by the crater or tip of the positive electrode and arranged to maintain the tip or crater of the positive electrode at or near the focal center of the reflector,.or other predetermined position.

It has been found that the devices of the prior art are deficient in many ways as they do not function to accurately control or constantly maintain the tip of the positive electrode in the desired position, do not provide a smooth feeding action, are complicated in construction which requires constant maintenance and are adversely affected by changes in temperature.

It is the object of my invention generally stated, to provide a feeding device for positive electrodes in arc searchlights which shall be of simple construction, economical to manufacture and install, which shall be efficient and accurate in operation, which will feed the electrode in a smooth manner and be capable of ready adjustment and which shall not be adversely affected by temperature changes.

The object of my invention, more specifically stated, is to provide for feeding apositive are light electrode in accordance with the position of the tip or crater thereof.

Another object of my invention is to provide for utilizing a photo-voltaic cell or device for maintaining the tip or crater of an electrode at a predetermined location with respect to the reflector or lens with which it is used.

A still further object of my invention is to provide for automatically controlling the feeding operation of an electrode by means of a light-responsive voltage-generating device responsive to the radiant energy of the electrode tip.

Another object of my invention is to provide for automatically maintaining the tip of an electrode at a predetermined position with respect to the reflector or lens of an-arc light by utilizing a self-energizing system or device responsive to electro magnetic radiation produced at the tip,

of the electrode.

These and other objects of my invention will become evident from-a reading of the following detailed description in conjunction with the drawings in which:

Figure l is a diagrammatic view of a feeding I system for the positive electrode of an are search-- light embodying the principal features of my invention,

Fig. 2 is a diagrammatic view of a modification of the system of Fig. 1 and Fig. 3 is a diagrammatic view of another embodiment of my invention.

In practicing my invention in its most elementary and generic form, feeding mechanism for the electrode regardless of the particular type used, is controlled by a voltage-generating device which may take the form of a photo-voltaic cell which is so positioned with respect to the tip of the electrode to be controlled as to function only when the electrode tip deviates from a predeter- 1 mined normal position, that is, when the electrode burns away so that the tip is no longer at or near the focal center vof the reflector of the searchlight or any other predetermined position, the photo-voltaic cell is subjected to the radiant energyproduc'ed at the electrode tip and functions to cause the feeding mechanism to move or advance the electrode until the tip is again in normal position. The functioning of the photo-voltalc cell is controlled by means of suitable baffles,

shields or the like placed between it and the electrode tip.

Referring now to Fig. 1 of the drawings, there is illustrated in schematic form one concrete em bodiment of my invention as it may be applied for controlling the feeding operations of the positive electrode of an arc searchlight. The numeral Ill designates the negative electrode and II the positive electrode. The negative electrode Iii may be supported in any suitable well known manner and its feeding operations controlled by the feed rolls I2, which may be driven to control the striking of the arc and thereafter to feed the electrode to the arc in any suitable manner well known in the art.

In this instance, the feeding mechanism for the positive electrode II is shown generally at I3 and provides for both feeding and rotating the electrode. The feedingmechanism I3 comprises a sleeve I4 on which oppositely disposed feed rolls I5 and I6 are supported. As will be readily under stood, the sleeve I4 may be rotatably supported in any suitable manner on the head of the searchlight (not shown), and may be rotated by any suitable mechanism which may or may not constitute a part of the feeding mechanism for the negative electrode.

In order to provide for actuating the feed rolls I5 and I6 to feedthe electrode II forwardly as I When the sleeve I4 is rotated, the gear element I! will also rotate and there will be no relative movement between it and the pinion 23 so that the feed rolls will not be driven in either direction. This operation merely causes the feed rolls to be revolved about the axis of the electrode, thereby rotating the electrode without feeding it in either direction. It is apparent, however, that rotation of the feed rolls occurs whenever the gear I! is held stationary to cause relative movement between the pinion 23 and the toothed portion 24.

It is to be understood that the particular type of feed mechanism described has been used for the purpose of illustration only and that any other suitable device may be used as well.

The feeding mechanism l3 may be actuated in any suitable manner such for example as by means of the motor 25 which is connected to the sleeve M by means of beveled gears 26 and 21. As described hereinbefore, the motor 25 may comprise a part of the negative electrode feed mechanism or it may function as a separate element preferably actuating the feed mechanism [3 at a substantially constant speed.

In order to cause the feed mechanism l3 to become operable to actuate'the feed rolls l5 and I6, there is provided a stopping device or pawl 28 in the form of a plunger which, when actuated to the upper position, engages another toothed portion 29 of the gear I! to hold.it stationary with'respect to the rotating sleeve I4. In this instance, the stopping device 28 is actuated directly by ele'ctromagnet 3|, which may be energized from the current source comprising conductors 32 and 33. v

In order to control the feeding operations of the positive electrode in such manner as to maintain the tip 34 thereof at or near the focal center of the Searchlight or other predetermined po- -sition, provision is made for rendering the feed controlling electromagnet 3i responsive to the position of the electrode tip. In this instance, the energization of the electromagnet 3i is controlled by means of a suitable relay 35. In order to effect the operation of the relay 35 whenever the electrode tip recedes from a predetermined position, there is utilized a light-sensitive device 35 which is so positioned with respect to the electrode tip 34 that it controls the operation of relay 35 in response to the movements of the positive electrode.

In this instance, the light-responsive device 36 is illustrated in the form of a photo-voltaic cell, which functions when the radiant energy of the electrode tip is directed upon it to develop a voltage of suflicient magnitude to operate the relay 35. It is apparent that a photo-voltaic or photovoltage cell of any form may be used for this purpose.

In order to direct the radiant energy from the electrode tip upon the photo-voltaic cell any suitable means such, for example, as light barriers 31 and 38 may be utilized. As shown, when the electrode tip is in the position shown in the drawings, the maximum amount of radiant energy is permitted to fall upon the cell which causes it to develop its maximum voltage to operate the relay 35 to its closed position, thereby energizing the electromagnet 3| which causes the feed mechanism to function to feed the electrode forwardly. As the electrode tip advances, the barriers 31 and 38 reduce the radiant energy which falls upon the cell until a point is reached where the cell no longer is energized sumciently to develop the required voltage which causes the relay 35 to open and stop the feeding operation. As soon, however, as the electrode burns away sufliciently to permit the greater amount of radiant energy to fall upon the cell, the feeding operation is again initiated.

It is also to be understood that any other suitable means may be used to direct the radiant energy from the tip of the positive electrode upon the cell or device 36, such for example as a lens or the like suitably positioned between the electrode and the cell.

The electrodes l0 and II are energized in this instance from the conductors 32 and 33 by means of suitable brushes or contact elements 4! and 42, the energizing circuit including the ballast resistor 43.

In view of the foregoing description, it will be apparent that the relay 35 and electromagnet 3| function in somewhat the same manner as a regulator, thereby continually advancing the positive electrode as fast as it is consumed, the degree of movement of the electrode being dependent upon the length of time during which the gear element I1 is held stationary.

'Referring now to Fig. 2 of the drawings, there is illustrated a positive electrode feeding mechanism in which the photo-voltaic cell principle is utilized for directly controlling the speed of the feeding motor.

' In this instance the positive electrode II is fed by means of rolls 44 and 45 and is rotated by a separate pair of rolls 46 and 41. As in the system shown in Fig. 1, the rolls 46 and 41 may be actuated by means of a motor 48 which may or may not constitute a part of the negative electrode feeding mechanism. The motor 48 is preferably operated at substantially constant speed in order to insure uniform burning of the positive electrode.

' In this instance the feed rolls 44 and 45 are actuated by a separate variable speed feed motor 49 connected thereto through gears 5 I.

The feed motor 49 is connected across the source represented by conductors 32 and 33 through a suitable resistor 52 and its speed adjusted so that the positive electrode H is moved forwardly at a speed which is'slightly lower than the feeding speed necessary to constantly maintain the electrode tip at the desired position.

In this instance, the photo-voltaic cell 36 and relay 35 are utilized to control the effectiveness of the resistor 52, and thereby control the speed of the feed motor 49 by varying the resistance of its armature circuit.

As will be readily understood, when the positive electrode tip recedes to the position shown, the photo-voltaic cell develops a maximum voltage, thereby actuating the. relay 35 to short circuit a portion of the resistor 52. This increases the speed of the feed motor to cause the electrode to be advanced at a higher speed than it is being consumed, thereby moving the tip thereof toward the focal center of the reflector or to some other predetermined position.

In Fig. 3 there is illustrated another embodiment of my invention somewhat similar to that shown in Fig. 1 with the exception that in this instance the gear element l'!- of the feeding device I3 is disposed to be driven by a feed motor ahich'is connected thereto by suitable gearing As will be readily understood, when the gear element ll'is driven by the feed motor 53 at the same speed as the sleeve I4 is driven, the feed rolls Ii and Il will not rotate so that the electrode II is not advanced or retracted. As soon, however, as the gear element i1 is caused to rotate relative to the sleeve l4, rotation of the feed rolls results.

In this instance, the armature resistor 52 may be adjusted to cause the feed motor 53 to continually advance the electrode at a slightly slower speed than is required to compensate for the burning away of the electrode tip. When the electrode tip recedes a predetermined distance from the desired position, as determined by the adjustment of the light barriers 31 and 38, the photo-voltage device 36 will function to energize the relay 35, thereby shunting the resistor 52 and increasing the speed of the feed motor II.

The feed motor 53 now functions to advance the electrode II at a faster rate than its rate of consumption and returns the tip to the normal or desired position at which point the resistor 52 is again rendered fully effective and the speed of the feed motor reduced.

It is, therefore, apparent that with this arrangement, the positive electrode is being continuously advanced, the photo-voltage device and relay 35 again functioning in somewhat the same manner as a regulator to positively maintain the tip of the electrode at or near the desired position by means of a smooth and positive feeding motion.

Furthermore, it is evident that therelative positions of the electrode tip, barriers 31 and 38 and the photo-voltage device 36 may be such that a very sensitive form of feeding device is provided, so that there is very little deviation of the electrode tip from the desired position which greatly increases the steadiness of the arc and the efficiency of the lamp.

While armature control of the feed motor has been illustrated in both Figs. 2 and 3, it is apparent that the application of my photo-voltage control is not necessarily limited to this particularform of motor control, since the relay 35 may beutilized to control the functioning of other forms of motor speed controlling devices well known in the motor control art.

In view of the foregoing, it is apparent that I have provided an electrode feeding mechanism which is of simple nature, and which has many desirable features over electrode feeding mechanisms of the prior art. It is apparent that by the use of the photo-voltaic cell. no outside source of voltage is necessary and that the control is unaffected by changes in temperature, since its function is dependent entirely upon the radiant energy produced at the tip of the electrode.

While the invention has been illustrated and described in connection with are searchlights, it is apparent that it may be applied to other kinds of arc lights where it is desired to constantly and accurately maintain the tip of the electrode at a predetermined position.

It may be stated in conclusion that while the illustrated examples constitute practical embodiments of my invention, I do not wish to limit myself strictly to the exact details herein illustrated, since modifications in the same may be made without departing from the spirit of the invention as defined in the appended claims.

I claim as my invention:

1. In a system for controlling the; feeding of electrodes in arc circuits having cooperatingelectrodes comprising an electrode which, is to be maintained in a predetermined position, an electrode holder, feed rolls mounted on said electrode holder and engaging the electrode to produce rotation of the electrode about its longitudinal axis when the electrode holder is rotated, means for continuously rotating the electrode holder,

a rotatable element mounted on said electrode tion of the electrode in the arc while the arc is burning, and means responsive to the position of the electrode for controlling the speed of rotation of said means for continuously rotating said rotatable element to thereby vary the rate of feed of the electrode in response to predetermined positioning of said electrode.

2. In a system for controlling the feeding operation of electrodes in arc circuits having cooperating electrodes comprising an electrode the arc tip of which is to be maintained in a predetermined position, an electrode holder, feed rolls mounted on said. electrode holder and engaging the electrode to produce rotation of the electrode about its longitudinal axis when the electrode holder is rotated, means for continuously rotating the electrode holder, a rotatable element mounted on said electrode holder, means for continuously rotating said rotatable element, means responsive to the differential movement between said rotatable element and said electrode holder for rotating said feed rolls to continuously feed the electrode toward the arc while the arc is burning, means for varying the speed of rotation of said means for continuously rotating said rotatable element, a light responsive voltage generating element, and means whereby said light responsive element controls said speed varying means, said light responsive element being so positioned as to be affected by the light from said arc'tip' when it moves from said predetermined position while the electrode is arcing.

3. In a system for controlling the feeding operations of electrodes in arc circuits having coopcrating electrodes, in combination, an electrode, an electrode holder, feed rolls mounted on said electrode holder and engaging the electrode to produce rotation of the electrode about its longitudinal axis when the electrode holder is rotated, means for continuously rotating said electrode holder at a substantially constant speed, a rotatable member mounted on said electrode holder, a variable speed motor for rotating said rotatable member continuously, means responsive to the differential movement between said electrode holder and said rotatable member for'rotating said feed rolls to continuously feed said electrode, means for so controlling the differential speed between said electrode holder and said rotatable member as to provide a predetermined rate of feed of said electrode, alight responsive cell so situated as to be affected by the light from the electrode upon predetermined movement of the tip of the electrode from a predetermined position while there is an are burning between the cooperating electrodes, means for increasing the speed of said variable speed motor and means whereby said light responsive cell controls said speed increasing means.

WILLIS A. PENNOW.

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