US1684655A - Arc lamp - Google Patents

Description

C. S. ASHCRAFT ARC LAMP Sept. 18, 1928. 1,684,655

Filed Sept. 19, 1923 5 Sheets-Sheet 1 (answer e1 imam/V Sept 18, 1928.

C. S. ASHCRAFT ARC LAMP Fi1ed Sept. 19,- 1925 3 Sheets-Sheet 2 CAME/v05 JAmcm/ r Patented Sept; 18, 1928.

' UNITED STATES CLARENCE S. ASHCRAFT, F LOS ANGELES, CALIFORNIA.

ABC LAMP.

Application filed September 19, 1923. Serial No. 663,569.

This invention relates to are lamps of the type provided with electrically operated mechanisms for feeding, the electrodes towards the are so as to compensate for the disintegration of the electrodes at the arc and thereby maintain a substantially constant are during operation of the lamp. This invention is a continuation in part of my co-pending application, Serial No. 488,849, filed August 1,1921.

In my co-pending application there is described an arc lamp having electrically operated mechanisms for automatically maintaining a constant are between the electrodes.

However with the lamp of the co-pending application the electrodes must be manually adjusted by an operator when lamp is to be started so that the electrodes may be struck togeth-- er and the are formed. This compelled the lamp to be positioned where it was within reach of the operator and had a further disadvantage that the striking together of the electrodes burnt away one side of the crater on the positive electrode with the result that a dark spot could be seen in the radiated light which persisted several minutes after the are lamp was started.

An important object of this invention is to provide a form of arc lamp which is entirely automatic in operation and automatically and rapidly establishes the are when current is supplied to the lamp and automatically adjusts the length of the'arc to maintain a constant arc while the lamp is in operation, so that resultant lamp may be operated from a locality or position spaced from the lamp.

By this invention notonly is the necessity of manually striking thearc eliminated but the arc is rapidly established with the result 4 that the crater of the positive is not destroyed and the lamp starts immediately to send off a uniform ray of light. i e

Another 'ob eet of this invention is to pro vide a niore'simple {and"economi'c'abmechanisi'nfo'r maintaining a uniform length of are than tlie mechanism described" in said 00 pending application. Morespeci'ficallyone objectjof this invention is to providea more i si'mple ineans forinterrupting the feeding of the positive "electrode 't'vhen an interrupted feed is required and another object is to protitle a mam-arse Qmaking' ?the negative feed y contin u o'us"and always in the tlii'ection" of the are. 55 Another object of this invention is to provide an arc lamp in which the relation between the speeds at which-the positive electrode and the negative electrode advance may be varied and controlled at will in the are scription of the accompanaying drawings and will be found in practice or use of the,

invention. In the accompanying drawings I have illustrated a preferred example embodying this invention, but desire to be understoodto the efi'ect that while such preferred example incorporates the spirit of this invention, various changes may be made in the form of the lamp without departing from the spirit of the invention.

In the drawings Figure 1 is a side elevation of this embodiment of the invention.

Fig. 2 is a rear elevation of mechanism for interrupting feed of the positive electrode. 4

/ Fig. 3 is a side view of the mechanism shown in Figure 2.

Fig. 4 is a view looking in a direction par-- allel to the axis of the negative electrode of the negative operating mechanism.

Fig. 5 is a section on the line 5 5 of Fig.

through the so Fig. 9'is-a section on the liner9.9a,ofFig.z8p In thedrawings, the are lamp-is provided with a: positive electrode. generally indicated by-A and a negative electrode genera'llyindie cated by Bfi The' electrodes' are arranged with one end of each? electrode adjacent one end of the other elect-rode'and' theangle@be1-1 twee'nithe electrodes is Z preferably. greater than 5 a right. angle and less; than 135? 1 The; positive electrode; is. preferably -'positioned with its axis parallelftoithe directioihthe light is intended to be radiated. In order to produce a uniform intensity of are it is necessary to rotate the positive electrode, otherwise the crater of the positive electrode would become irregular in shape, elongated at one side more than the other. Under such conditions, the direction at which the light was radiated would continually change.

It is likewise necessary to advance the electrodes of the lamp to compensate for the rate at which the electrodes burn or disintegrate.

A mechanism for producing both a continu-- ous rotation of the positive electrode A and for advancing such electrode will now be described. The positive electrode A passes loosely thru a bushing 2 which encloses a por tion of the electrode. The bushing 2 is journa-lled by an anti-friction bearing 3 supported in a casting 4. Thebushing 2 provides a circular plate 5 surrounding the electrode A, which plate 5 is provided with inwardly projecting brackets 6, each pair of brackets supporting a stud 7 which engages in radial slots 8 formed in the brackets, said slots permitting of radial movement of the studs relative to the axis of the drum. Adjacent ends of studs 7 are connected to each other by coiled springs 9, which yieldingly hold the studs 7 towards the axis of the drum. The opposite ends of the studs 7 are provided with clamps 10 held together by a screw 11. On each stud 7 between each pair of brackets 6 is rotatably mounted aspur gear 12. In the drawings two of such gears are illustrated, but it is understood that more or fewer of such gears may be employed if desired. The gears 12 engage a spiral hoop gear 13 which is formed on the forward vertical face of a control member 14 which is rotatably mounted on the bushing 2. The control member 14 provides a means for controlling the rotation of the gears 12 about their axes. Thus, if the control member 14 and the plate 5 mounting the gears 12 are both rotated at equal speeds the gears 12 Will not rotate around their axis. If the rates of rotation of the control member 14 and the plate 5 are not equal then the spiral hoop gear 13 will cause the gears 12 to rotate. Thegears 12 are adjusted by the screw 11 and tenslon of the spring 9, so that they engage the electrode A. Thus the rotation of the gears 12 will cause the electrode A to move in an axial direction. The spiral hoop gear 13 1s formedso that when the rate of rotation of the control member 14 is less than the rate of rotation of the plate 5 or bushing 2, the gears 12 are rotated in a direction to cause the electrode A to advance the electrode towards the arc. The rotation of the bushing 2 and plate 5 is effected through a bevelled gear 15 secured to the rear end of the bushing 2 and driven from a shaft 16, carrying a bevelled gear 17 meshing with the gear 15.

The rotation of the control member 14 is regulated by a ear 18 formed on the rear of said member. he gear 18 engages a pinion 19 secured to a horizontal shaft 20 journalled in the casting 4. The shaft 20 is provided with a ratchet wheel 21 engaged by a pawl 22. The pawl is rigid with an arm 23 supporting a detent 24. The detent 24 is positioned with one end extending towards the back of the bevelled gear 15 where it may engage one of a number of studs 25 projecting from the rear of said gear 15. (See Fig. 2.). The detent 24 has screw engagement with the arm 23 so that the detent may be screwed towards or away from the studs 25 as the operation of the lamp may require. The pawl 22 and arm 23 as a unit are fixed to a shaft 26 which is journalled in the casting 4. 27 indicates a spring which yieldingly maintains the pawl 22 engaging the ratchet wheel 21. By this construction the control member 14 is normally held from rotating with the bushing 2 due to the pawl 22, engaging said wheel 21, and thus the electrode A is normally continually advancing towards the arc. Under certain conditions hereinafter described it is necessary to interrupt-the feed of the electrode in which case the detent 24 is moved towards the studs 25 until the studs 25 on rotating will engage the detent and pivot the detent 24 back, against the pressure of the spring 27, to permit the studs to pass. This releases the pawl 22 from the wheel 21 and the control member rotates with the rotation ,of the bushing 2, and the advance of the positive electrode 15 interrupted. In the drawings there is shown three of the studs 25 which will cause the feed of the electrode A to be interrupted three times during each revolution of the bushing 2. Obviously more or less of the studs 25 could be provided if desired. The length of time each stud will interrupt the feed of the electrode A will depend upon the distance the detent 24 is screwed towards the studs. To support the positive electrode A and its rotating and feed mechanism the casting 4 is secured to a horizontal support 28. Said support 28 is fixed to the top of a frame 29 by bolts 30 and electrically insulated from said frame by an insulating block 31 between the frame 29 and support 28. The frame 29 is bolted at its lower end to a lower frame 32 which serves to support certain parts of the negative feeding mechanism.

The rear end 33 of the frame 32 is turned vertically downward. Bolts 34 extending rearwardly from the frames 29 and 32 support vertical standards 35 to which an electric motor 36 is fastened. The motor 36 is provided with a worm 37 at the lower end of its armature shaft. A worm wheel 38 engages teeth of said worm and isfixed to a shaft 39 journaled in a housing 39' enclosing said worm and gear. The shaft 39 is provided with a flexible coupling 40 and terminates in a worm shaft section 41. The shaft 16, -which drives the bushing 2, extends vertically downward in the lamp and provides a worm Wheel 42 engaging the worm section 41.

From the foregoing it will be clear that operation of the motor 36 willproduce a comparatively slow rotation of the electrode A, and. also when the pawl 22 is engaging the wheel 21, will produce a rotation of the gears 12. The various gears are so proportioned relative to the speed of operation of the motor 36 that the speed at which the electrode A advances is just slightly faster than the speed at which the electrode A is consumed, so that it is then possible with a minimum interruption of the positive electrode to bring the speed of advance of the positive electrode equal to the speed at which said electrode is consumed. Exact adjustment of the detent 24 is not necessary since a further control of the speed at which the electrode advances is accomplished by automatic control of the speed of the motor 36 in a manner hereinafter described. j

The mechanism for feeding the negative electrode 13 will now be described. The vertical shaft 16 is provided at its medial portion with a bevelled gear 43 meshing with a bevelled gear 44 carried on a negative electrode operating horizontal shaft 45. The shaft 45 is j ournalled in the frame 29. 46 indicates a frame pivotally mounted on the lower frame 32. Said frame 46 provides a bearing 47 for a shaft 48 which is inclined upward and joined by a universal joint 49 to the negative electrode operating shaft 45. The negative electrode is held by a clamp 50 extending from a carriage 51. The carriage 51 is adapted to slide along two parallel rods 52 secured together by blocks 53 at their ends, the carriage 51 having tubular slides 54 telescoped over the rods. Journalled at its ends in the blocks 53 is provided a worm shaft 55having a bevelled gear 56 meshing with a bevelled gear 57 fixed .to the inclined shaft 48. The upper block 53 is bolted to a flange 58 extending from the bearing 47 thus supporting the negative electrode B on the pivoted frame 46. The carriage 51 is provided with a toothed catch 59 which normally engages the worm shaft 51 to feed the carriage 55 and electrode B upon rotation of the shaft 55.

The catch 59 is preferably fixed to a bar,

such as 60, which is pivoted to the carriage at one end and the other end is yieldingly urged towards the worm shaft 55 by a spring 61, so that while normally the catch is in engagement with the shaft 55 the catch may be released to manually shift the electrode along the rods 52.

Below the frame 32 is secured a solenoid 62 which provides an automatic means for striking the are when operation of the lamp is to be started. The solenoid comprises an electro-Inagnet 63 having an armature 64, The armature 64 is fixed to an arm 65 provided by the pivoted frame 46 and is pressed against a pin 66 engaging a coiled spring 67 set in the front end of the solenoid. 68 indicates a bolt which may be adjusted to vary the pressure exerted by the spring 67 through the pin 66 upon the armature 64.

The electro-magnet 63 is connected to the mains so that the current sent through the electro-magnet 63 will draw the armature 64 which will tend to cause the frame 46 to pivot upward and strike the positive electrode A.

Referring to Fig. 7 the electrical wiring of the lamp. is shown. The negative supply main 70 connects with a ballast resistance 71 from which current is supplied to the negative electrode B being connected to the clamp 50 pressed across the elcctro-magnet 63 and motor 36.

\Vhen the arc lamp is to be operated the current is first switched on. At the time the current is turned on 'the current cannot flow across the gap between the electrodes and start the arc unless the electrodes are first struck together. This striking of the electrodes is effected by the solenoid. The electro-magnet 63 of the solenoid is constructed so that when the lamp is in operation the current through the magnet 63 is insufficient to draw the armature 64 into the magnet and pivot the electrode B up to strike the electrode A. Before the arc is struck, however, a much larger current is sent through the electro-magnet 63 due to the high resistance of the gap between the electrodes, and under such conditions the electrode is rapidly forced upward to strike the arc. When the electrodes strike together the resistance to travel of the currentthrough the electrode path becomes practically zero and accordingly the current through the electromagnet 63 becomes very low permitting the electrode B to immediately drop back from electrode A.

The motor 36 then rotates at av speed pro portional to the voltage across the arc and advances both electrodes at a rate to compensate for the disintegration of the electrodes. Thus if the speed of the electrodes becomes insuiiicient to equal the rate of con sumption of the electrodes the resistance across the arc will increase, producing a higher are voltage, this causes a greater current to be sent through the motor and accordingly the same will speed up, and likewise when the speed at which the electrodes advance becomes too rapid the length of the arc will decrease, resulting in a decrease in lift the resistance across the arc lowering the arc voltage and less current will then flow through the motor and the speed of advance of the electrodes will be retarded.

However, in cases where a great variation in the voltage on the mains may occur the motor 36 may not be able to maintain the are constant with bot-h the feeds of the negative and positive electrodes continuous. In such cases it is preferable to fix the pitch of the hoop gear 13 so that the positive electrode will normally feed slightly faster than the electrode is consumed and adjust the feed of the positive electrode with the interrupting mechanism. However. it is to be remembered that continuous feed of the positive electrode produces the most uniform arc, and that when the feed must be interrupted at short intervals, the time during which the feed is interrupted should preferably be less than the time during which the electrode is feeding toward the are.

I have found that this manner of feeding the positive electrode enables the arc lamp to burn as long as five to ten times the period of time that an arc lamp, in which the positive electrode is jerked towards the arc and the periods of interruption greatly er;- ceed the periods during which the positive electrode is being fed, can be burned without requiring attention from the operator.

Other advantages of this invention are that V the lamp is entirely dependable in operation,

electrodes of varying diameters may be employed, the lamp is easy to operate, simple and economical in construction.

I claim:

1. In an arc lamp having a positive electrode, a negative electrode, and means for advancing the electrodes, the combination of: an are striking means comprising a negative electrode carriage so disposed as to normally hold said negative electrode separated from saidpositive electrode by the weight of said carriage; and electro-magnetic means operative by the throwing on of the are circuit for striking said negative electrode against said positive electrode, the striking of the are being efi'ective to reduce the strength of the pull of said electro-magnet whereby the weight of the carriage will cause it to fall back to normal operating position.

2. In an arc lamp having a positive electrode, a. negative electrode, and means for advancing the electrodes, the combination of: an are striking means omprising a negative electrode carriage so disposed as to normally hold said negative-electrode separated from said positive electrode by the weight of said carriage; electro-magnetic means operative by the throwing on of the are circuit for striking said negative electrode against said positive electrode; and a compression spring adapted to assist in return of the carriage to normal operating position.

3. In an arc lamp: an electrode holder; an electrode supported by said holder; means for rotating said holder on the longitudinal axis of said electrode; means carried by said holder adapted to revolve therewith and to be rotated for advancing said electrode; a spiral gear mounted on and adapted to rotate with said holder and adapted to rotate said last named means when its own rotation is retarded; and means for periodically retarding the rotation of said gear.

at. In an arc lamp; an electrode holder; an electrode supported by said holder; means for rotating said holder on the longitudinal axis of said electrode; means carried by said holder adapted to revolve therewith and to be rotat d for advancing said electrode; a spiral gear mounted on and adapted to rotate with said holder and adapted to rotate said la t named means when its own rotation is retarded; and means for periodically retarding the rotation of said gear, the last mentioned means comprising a first gear secured to said spiral gear, a second gear adapted to actuate said first gear, and a pawl adapted to engage said second gear and to be moved out of engagement therewith by the rotational movement of said holder.

In an arc lamp': an electrode holder; an electrode supported by said holder; means for rotating said holder on the longitudinal axis of said electrode; means carried by said holder adapted to revolve therewith and to be rotated for advancing said electrode; a spiral gear mounted on and adapted to rotate with said holder and adapted to rotate said last named means when its own rotation is retarded; and means for periodically retarding the rotation of Said gear, the last mentioned means comprising a first gear secured to said spiral gear, a second gear adapted to actuate said first gear, a pivoted pawl adapted to engage said second gear and to be disengaged therefrom, a stud carried by said holder, a detent secured to said pawl and adapted to be moved by said stud, whereby said pawl is moved out of engagement with said second gear.

4. 6. A combination as described in claim 5 in which said detent is adjustable.

7. In an arc lamp: an electrode holder; an electrode supported by said holder; means for rotating said holder on the longitudinal axis of said electrode; means carried by said holder adapted to revolve there with and to be rotated for advancing said electrode; a spiral gear mounted on and adapted to rotate with said holder and adapted to rotate said last named means when its own rotation is retarded; means for periodically retarding the rotation of said gear, the last mentioned means comprising a first gear secured to said spiral gear, a second gear adapted to actuate said first gear, a pivoted pawl adapted to engage said second gear and to be disengaged therefrom, a stud carried -by said holder, a detent secured to said pawl and adapted to be moved by said stud, Whereby said pawl is moved out of engagement With said second gear; and means for returning said pawl into engagement with said second gear.

8. In an arc lamp: an electrode holder; an electrodecarried by said holder; means for advancing said electrode in said holder; and means actuated by said holder for periodically interrupting the action of said means for advancing the electrode, said last named means including means for varying the period of duration of said interruptions.

9. In an arc lamp: an electrode holder;

means for rotating said holder; means actuated by the rotation of said holder to advance an electrode disposed therein; and meansactuated by said holderperiodically relative to the rotation thereof to interrupt said electrode advancing means.

10. In an arc lamp: an electrode holder; means for rotating said holder; means actuated by the rotation of said holder to advance an electrode disposed therein; and means actuated by said holder periodically relative to the rotation thereofto interrupt said electrode advancing means, the periodicity of the actuation of said last mentioned means being adj ustahle.

Signed at Los Angeles, Californiaithis 31st day of July, 1928.

CLARENCE S. ASHCRAFT.

Images