US1521361A - Arc lamp - Google Patents

Description

Dec. 30. 9 1,521,361

'A. P. DAVIS ARC LAMP Filed Dec. 51, 1917' 2 Sheets-Sheet 1' INI/E/VTOR ATTORNEF S.

Dec. 30, 1924.

A. P. DAVIS ARC LAMP 1 Filed Dec. 51',

1917 2 Sheets-Sheet 2 IN l/E N TOR A TTORNEYS Patented Dec. 30, 1924.

UNITED STATES ARTHUR P. DAVIS, OF BROOKLYN, NEW YORK,

ARC LAMB.

Application filed. December 31, 1917. Serial No. 209,638.

useful Improvements in Are Lamps; and

I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

'This invention relates to electric arc lamps and more particularly to lamps of the type generally known as flaming arc lamps. The invention is directed to the provision of an improved construction of the mechanism for supporting the electrodes in their proper relative positions, for actuating the electrode supports to draw the arc and compensate for the consumption of the electrodes, for discontinuing the operation of the mechanism when the electrodes have been consumed to a predetermined extent, and for facilitating the operations incident to trimming the lamp.

One of'the features of the invention involves the construction of the electrode supports. These consist of a support for one electrode mounted upon a carriage 30 which is movable in a straight line and a support for the other electrode which is pivotally mounted and which is provided with parallel motion devices whereby as the support is turned about its pivotal axis the'electrode carried thereby is rocked on an axis so as to maintain the desired angular relation of the two electrodes throughoutthe operation of the lamp.

Another feature of the invention involves co. the construction of the operating mechanism for moving the two electrode supports. This includes an electric motor which is connected through an automatic reversible clutch to a reversely threaded shaft, the ends of which are arranged to actuate the two electrode supports. The automatic clutch depends for its operation upon the speed of rotation of the motor shaft and this speed is in turn dependent upon the electrical conditions prevailing from time to time in the circuits of the lamp. If the circuit to the electrodes and the motor-armature be closed when the electrodes are separated, a relatively high voltageis impressed upon the motor armature and the high speed of rotation resulting operation of trimming. The

therefrom brings the electrodes together. The closure of the arc circuit thus effected causes an immediate drop in the voltage impressed upon the armature of the motor, reducing its speed substantially and this speed reduction operates through the automatic clutch to cause the electrodes to be separated so as to draw the arc. The operation of the motor and the automatic clutch from that time on responds to the voltage drop across the arc in such a way as to effect the necessary feed of the elec trodes and maintain their adjacent ends at the requisite distance apart.

Another feature of ,the invention involves the provision of a fly wheel upon the motor shaft whose function is to effect the initial separation of the electrodes after they have been brought together by the actuating motor. When the ends of the two electrodes are brought together by the motor in striking the arc, the arc circuit is closed with practically no resistance drop from one electrode to the other; the motor armature is thus short circuited. But the presence of the fly wheel upon the motor shaft contill tinues the rotation of the motor shaft at reduced speed and this rotation is sufl'icient to effect the initial separation of the electrodes and thereby establish a Voltage drop across the arc and across the motor armature to cause the motor to continue the separating movement of the electrodes.

Another feature of the invention involves the provision of a novel form of switch for discontinuing the operation of the lamp after a predetermined consumption of one of the electrodes and for facilitating the actuating member of this switch is arranged to he engaged by one'of the electrode supports to discontinue the operation of the mechanism for feeding the electrodes so that the arc is elongated until finally it breaks. Tn combination with these parts means are provided for moving the actuating member of the switch handle to a third position in which the circuit of the actuating motor is closed through a resistance for retracting the electrode supports to the positions of greatest separation preparatory to. substituting new carbons'for the stubs of ones formerly used. This manual operating device has a part which liesin the path of movement of one of the movable electrodes so that if the operator fails to dis continue the separating movement within the proper time, this will be effected auto matic lly.

These and other features of the invention will be better understood by reference to the following description taken in connection with the accompanying drawings which illustrate the preferred embodiment of the invention. In these drawings, Fig. 1 is a sectional elevation of the entire mechanism; Fig. 2 is a vertical section on line 22 of Fig. 1, and Fig. 3 is a diagram of the circuits employed.

Referring to these drawings, 4 indicates a base plate upon which all of the parts of the lamp are mounted. A pair of guideways 5 are mounted upon this base plate extending along opposite sides thereof. The positive electrode 6 is' mounted upon a carriage which is adapted to travel back and forth in these guides 5. This carriage consists of arms 7 mounted upon a plate 8 which is secured to axles 9 having wheels 10 on the ends thereof adapted to travel in the guides 5. The upper ends of the arm 7 are secured to a block 11 having a central opening within which a sleeve 12 is secured. The ends of this sleeve are split, tapered, and threaded, and each end is adapted to receive a nut 13. In trimming the lamp, the positive electrode is passed through the sleeve 12 to the proper position and then the nuts 13 are tightened up upon the split ends of the sleeve until the parts of the sleeve grip the electrode firmly. The block 12 is provided with radial openings adapted to receive brushes 14 which are-pressed by springs 15 into contact with the sleeve 12 and wires from the positive side of the circuit are connected to these brushes 14 so that the current passes through the brushes and the sleeve 12 to the ele'trode 6.

The negative electrode 16 is supported in a sleeve 17 corresponding to the sleeve 12 and orovided with a nut 18 upon one of its ends. The sleeve 17 is mounted in a block 19 which IS pivoted to turn about an axis 20 upon two arms 21 which are pivotally mounted at 22 upon a plate 23 which is suspended from the base plate 4 by brackets 24. Current iscarried to the negative electrode 16 by a brush 25 passing through an opening in the block 19 and engaging the sleeve 17, and electrical cpngrection is made to the brush 25, as shown a 'As the negative electrode 16 isfed forward to compensate for consumption thereof, it and its supporting block 19 are turned about the axis 20 so as to always maintain the same angular relationof the negative electrode to the positive one. For this purpose the block 19 is provided with an extension 27 to which a rod 28 is pivotally connected. This rod isalso pivotally connected at its lower end to a cap 29 on the upper end of a stud 30 which is threaded in an opening in the plate 23. By turning the stud 30 the angular disposition of the negative electrode 16 may be adjusted as desired and when once adjusted, that angular disposition will be maintained throughout the feeding movement of the arms 21 about the axis 22.

The feed of the electrodes is effected by an electric motor 31 arranged to rotate a reversely threaded shaft 32 in one direction or the other. The threads at opposite ends of this shaft are of different pitches and the two pitches are in the relation of the consumption of the two electrodes. of the shaft 32 passes through a threaded opening in an extension 33 of the base 8 of the carriage for the. positive electrode 6. The other end of the shaft 32 passes through a threaded opening in a block 34 provided with trunnions 35 which extend through slots in the arms 21. Secured on the shaft 32 is a gear 36 through which the shaft is driven in either direction by the motor 31 through the automatic clutch.

The shaft 37 of the motor 31 carries a fly wheel 38 and also a centrifugal controller for the automatic clutch. Secured on the shaft 37 is a disk 39 to which the ends of spring arms 40 are connected. The positive ends of these spring arms are connected to a disk' 41 on a sleeve 42 which is splined by means of the pin and slot shown at 43 to the shaft 37. The spring arms 40 have weights 44 secured thereto which may be-connected by a coiled spring 45.

The end of the sleeve 42 carries a disk 46 which lies between two coacting disks 47 and 48 which are loose on the shaft 37 and sleeve 42 respectively. The disk 48 is integral with a gear 49 meshing with a gear 50 on 'a countershaft 51 which carries a pinion 52 meshing with the gear 36. The disk 47 is integral with a gear 53 meshing with an idler gear 54 which meshes with a gear 55 on the shaft 51. It will be noted that the position of the disk 46 is determined by the centrifugal governor. the disk being carried into engagement with disk 48 when the motor rotates at high speed and with the disk 47 when the motor rotates at low speed; when the disk is in clutching engagement with either of the disks 47 and 48. the shaft 32 is driven through the gears 52 and 36, but the direction of rotation is opposite in the two cases by reason of the provision of the idler gear 54 in association with the disk 47, whereas no idler gear is provided in association with the disk 48.

The shaft 37 is extended on the opposite side of the motor and carries a worm 56 meshing with the worm wheel 57 on a vertical shaft 58. This shaft 58 is connected through a telescopingshaft 59 and universal joints 60 to the shaft of a bevel gear 61 mounted on a cross-piece 62 extend- One end ing between the arms 7. This bevel gear 61 meshes with a bevelgear 63 secured to the sleeve 12.

Secured to the under side of the base plate 4 is a standard 64 on which is pivoted the operating arm 65 of a switch. On this arm is a pin 66 which is adapted to make contact with either of two spring arms 67 and 68 or to lie in a position between the two spring arms and disconnected from both of them. The pin 66 is normally held in the position shown in contact with the sprin arm 67 by means of a coiled spring 69. long sheet metal strip 70 lies on and is adapted to slide upon the upper surface,

of the base plate 4. In one end of this strip is an opening through which the arm 65 of the switch extends. The opposite end of the strip 170 is bent up as shown at 71 to lie in the path of movement of the carriage for the positive electrode.

Referring now to the circuits illustrated diagrammatically in Fig. 3, it will be noted that the positive and negative supply mains are connected to the positive and negative electrodes respectively, with the usual balancing resistance 72 connected in the positive lead. A switch 73 controlling the arc circuit is alsoinserted in this positive lead. The field 74 of the motor 31 is connected across the positive and negative wires at a-point beyond the balancing resistance 7 2 and a regulating resistance 7 5 is connected in series with the field. From a point beyond the switch 73 the positive lead is connected by a wire 76 to the switch arm 67 and the arm 65 of the limit switch is connected by a wire 77 to the armature of the motor 31. The arm 68 of the limit switch is connected by a wire 7 8 to the positive wire of the circuit at a point between the balancing resistance 7 2 and the switch 73, an auxiliary resistance 7 9 being inserted in this connection.

The operation of the mechanism thus constructed will now be described. When the lamp is not in operation, the points of the electrodes are separated more or less. With the parts in the positions indicated in the drawings, to start the lamp in operation, the switch 73 is closed. The electrodes beseparated, no current flows through them and the relatively high resistance drop I across the electrodes causes a relatively large current to flow through the armature of the motor 31, from the positive wire through the ballast resistance72, switch 73, wire 76, spring arm 67, switch arm 65 and wire 77 to the motor and then to the negative side of the circuit. As the field 74- of the motor is closed through the regulating resistance 75, the motor begins to operate at once and assumes a relatively high speed. This causes the weights l i to move outwardly and the disk 46 is carried into engagement the disk 48 thereby driving the shaft 32 through the gears 50, 52 and 36 in a direction to feed the electrodes toward each other. This continues until the electrodes have been brought into actual contact, whereupon they short circuit the armature of the motor. However, the rotation of shaft 37 does not cease when this occurs, by reason of the provision of the fly wheel 38. As the rotation of the shaft continues under the influence of the fly wheel, its speed decreases, and when the speed has fallen below a definite point the weight 44 moves the disk 46 into engagement with the disk 4C7, whereupon shaft 32 is rotated in the opposite direction through gears 53, 54, 55, 52 and 36. This separates the points of the electrodes to strike the arc and as the electrodes-are separated, the resistance drop between them increases. In correspondence with this increase in the resistance across the arc, the current flowing through the motor armature increases, continuing the rotation of shaft 37 to continue the separation of the electrodes, the shaft 37 being now driven electrically instead of by the fly wheel. The separating movement of the electrodes continues until the arc has been drawn to the required length, that is, until a time when the increasing current flow through the motor armature has brought the speed of the motor up to such a point that the disk 46 rotates freely between the two disks 47 and 48. In the operation of striking the are initially, there may be several backward and forward movements of the two electrodes caused by the disk 46 driving first the disk 47 and then the disk 48 small amounts, but the parts soon come to rest with the electrodes at the requireddistance apart. Throughout the operation of the lamp, the motor operates through the parts 56, 57, 58, 59, 60, 61 and 73 to rotate the positive electrode 6 at slow thepoints of the electrodes are consumed the resistance across the arc increases, thus causing corresponding increase in the flow of current through the motor armature until finally this increase is sufiicient to cause a "feeding movement of the electrodes through coaction of the disks 4-6 and 48.

The lamp continues in operation in this manner until the electrodes have been so far consumed that it is desirable to discontinue the operation. When this occurs, the forward edge of the carriage for the positive electrode engages the end of the arm 65 and moves that arm until the pin 66 is carried out of engagement with the spring arm 67. This opens the circuit of the motor armature 31 and thereby ,discontinues the operation of the feeding mechanism and as the electrodes are further consumed, the arc is elongated until finally it is snapped and speed so as to keep the arc properly centered upon the end of the positive electrode. As L- the operation of the lamp is discontinued. In trimmin the lamp thereafter the operator grasps t e handle 71 of the slide 70 and pushes it forward thereby actuating the arm 65 to carry the pin 66 into engagement with the spring arm 68. This closes the circuit of the motor armatureSl through the resistance 7 9. Current then flows through the motor armature but this current is so far reduced by the resistance 79 that the disk 46 is carried into engagement with the disk 47, thereby rotating the feed shaft 32 in the direction for separating the two electrodes. This action is continued until the electrode supports are moved to their outermost positions whereupon the stubs of the used electrodes are Withdrawn and new electrodes are substituted for them. It will be noted that if the operator fails to open the circuit of the motorarmature through the spring arm 68, this circuit will be automatically opened by the rear edge of the carriage 8 engaging the end 71 of the slide 70.

I claim:

1. In a flaming arc lamp, the combination of a holder for holding a positive electrode in a horizontal position, means for feeding the positive electrode in the direction of its axis, a holder for supporting a negative electrode in a position inclined to the horizontal, a pivoted support for the holder for the negative electrode, means for turning the supportabout its pivot to feed the negative electrode forward to compensate for consumption thereof, and means actuated in correspondence with the turnmg movement of the support about its pivot for turning the holder relatively to the support to maintain a predetermined angular position of the negative electrode relatively to the positive electrode.

2. In an arc lamp, the combination of a guideway, an electrode support movable along the guideway in a straight line, a second electrode support which is pivotally mounted, a holder for an electrode pivoted onthe'sec'ond support, operating mechanism for simultaneously moving the first support -ment of the second support for turning the holder relatively thereto to maintain a predetermined angular relation of the electrodes carried by the two supports; substantially as described.

3. In an arc lamp, the combination of a pair of movable electrode supports, a motor, a clutch mechanism through which the motor moves the supports toward and away from each other, a centrifugal device actuated by the motor and controlling the operation of the clutch mechanism, and means for closing the motor circuit through resistance to operate the motor at low speed to retract the electrode supports to -positions for trimming; substantially as described.

4..In an arc lamp, the combination of a pair of movable electrode supports, an electric motor for moving the supports toward and away from each other, a switch in the motor circuit engaged and operated by one of the movable electrodes, and means for moving the switch manually to close the motor circuit to cause the motor to move the electrodes away from each other; substantially as described. I

5. In an arc lamp, the combination of a pair of movable electrode supports, an electric motor for moving the supports toward and away from each other, a switch in the motor circuit engaged and operated by one of the movable electrode supports, and means for moving the switch manually to close the motor'circuit to cause the motor to move the electrodes away from each other, said means for moving the switch having a part which lies in the path of movement of one of the electrode supports so as to be actuated thereby when the-support nears the end of its outward movement; substantially as described.

In testimony whereof I aflix my si nature.

ARTHUR P. D VIS.

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