Improvements in Electric Arc Lamps.
Year: 1895

page_text: Date of Application, 11th July, 1895-Accepted, 17th Aug., 1895
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
T, JAMES DEVONSHIRE, Secretary of The British Thomson-Houston, Limited,
of 38, Parliament Street, Westminster, in the County of Middlesex, (a communi-
cation to me from abroad from Elihu Thomson, and Charles E. Harthan, residing
respectively at Swampscott, County of Essex, State of Massachusetts, and Lynn,
County of Essex, State of Massachusetts, both in the United States of America,
Electrical Engineers,) do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
My invention relates to electric arc lamps, and particularly to those adapted for
use upon constant potential or incandescent lighting circuits, and is especially
I can also run
useful where a single lamp is to be connected up in such a circut.
this lamp either by alternating or continuous current with equal efficiency and
success.
My invention has for its objects to simplify the mechanism; to lessen the cost of
construction; to secure delicacy of regulation and consequent perfection of feed, so
that the current passing in the are shall be approximately constant; to dispense
with the contacts so often a source of trouble in electric lamps; to provide a new
and efficient dash-pot which shall be so enclosed, and the wearing surfaces of which
shall be so protected that it is not liable to accumulate dirt and impair the
regulation by sticking; and further to provide a novel and useful core for the
series coil of the lamp.
To attain the ends pointed out, I construct my lamp so that its entire regulation
both in striking the arc and in regulating its length, is obtained by means of the
current in the series coil; and though I illustrate a particular form of gearing
I prefer to employ, I do not mean to limit myself to this particular feature, but
various modified forms of gear may be employed in place of the one shown, it being
my object to claim particularly the method of regulating an arc lamp, which
consists in performing the regulation by means of the current in the series coil
alone without shunt coils or contacts to be opened and closed, as well as the
particular apparatus shown.
In the accompanying drawings I illustrate an embodiment of my invention, and
therein
Fig. 1 is an elevation of our improved lamp, showing the working parts;
Fig. 2 is a detail with parts of the mechanism broken away to illustrate the
operation of the lamp ;
Fig. 3 is a section upon the line 3-3 of Fig. 1 of the dash-pot above
referred to;
Figs. 4, 5 and 6 are respectively a section, a side elevation and a plan of the
improved core for the series coil; and
Fig. 7 is an end elevation showing a modified arrangement of the gear frame
and springs by which the adjustment of the lamp is effected.
H is the upper part of the frame of the lamp; H' its lower part. These two
parts are, as usual, of cast metal and are united by the usual supports or
standards S, S', S². A series coil C is attached to any suitable part of the lamp
frame, preferably to the upper part H. K is the lower carbon with its holder
and K' the upper carbon, also in its holder attached to the rack-rod R meshing
with a small pinion h, shown also in Fig. 2, which is secured to the gear wheel W
by a ratchet and pawl s, allowing the free upward motion of the rod R, but
g

page_text: preventing its descent. This gear wheel W meshes with a small pinion W' attached
to the escapement wheel W; the shafts of all these wheels have their bearings in a
frame FF, pivotted at o to a supporting piece E extending from the frame to the
lamp. This frame F is connected to the iron core of the series coil, and projects
in the other direction a short distance beyond its pivot o. The connection between
the core and the frame is by means of a spring Z, the purpose of which will be
hereafter explained; while the end of the frame is attached to the piston of the
dash-pot D. A lever L also pivotted in the piece E is attached at one end
directly to the iron core I and also projects beyond its pivot o¹ in the other
direction. To assist the action of the coil upon the frame F, springs, 2 are
provided, the tension of which may be adjusted so as to get just such a balance as
is best for the feeding of the lamp between the weight of the frame F and its
contained gearing and the pull of the series coil C upon the core.
The escapement
wheel Wis held against rotation by the pawl e, which is double, as usually con-
structed, so that the teeth may escape singly, though it may be adjusted to feed
with more rapidity if desired; this pawl is pivotted in a movable lever L', which
itself is pivotted at o² and its extreme end beyond the pawle is engaged by the
lever Lin its movement. A pendulum P, for which may be substituted a suitable
spring, is provided to prevent the oscillation of the pawl except when the feed
should take place.
The circuit through the lamp is from the binding post B through the lower part
of the lamp frame to the lower carbon K, the upper carbon K', through the rack-
rod R, which is insulated from the lamp frame, thence to the brush G through the
series coil C and out at the other binding post B².
b
As
Instead of attaching the springs directly to the frame F, I may, and preferably
do, attach these springs to the bar z¹, with which the lever L connects.
already explained, the office of these springs is to assist in drawing up the frame F
against the weight of the parts supported by it. This arrangement is illustrated
in end elevation in Fig. 7. Referring to Fig. 3, I illustrate the construction of
the dash-pot which I prefer, the outside elevation being shown in Fig. 1, and a
partial section upon a line at right angles to the one shown in Fig. 3 being
illustrated in Fig. 2. Therein D is the outer cylinder, P2 is a double-ended piston
forming a close working fit in the cylinder D; a slot n in the sides of the cylinder
and a similar one in the piston permit the entrance of the end of the frame F, and
the pin q¹ secures the frame in place in the piston. This arrangement provides a
perfect protection against dirt, the piston being double-ended and forming a
hollow shell so that any dirt that may gain access to it is deposited on the inside
of this shell and cannot interfere with its motion in the cylinder D.
Referring now to Figs. 4, 5 and 6, I illustrate the improved core for the series
coil. To construct this, I assemble a bundle of soft iron wire of proper length, and
on each end of this I place insulating washers of asbestos or fibre; over the
washers put rings of insulating material. These three parts are lettered
respectively B2, W³, and R2. For the washers I prefer insulating material of
some strength, such as steatite, or lava, as it is commonly called. The core is
preferably wrapped with paper or some other thin insulating material, and I then
insert it into a shell of metal, preferably magnetic, and upon the ends of the shell
I form fingers, f, 12. These fingers are theu crimped down over the ring, and the
whole forms a strong construction within which eddy currents cannot circulate to
any great extent. The outer shell Q is slotted at qg, to further prevent the
circulation of such currents. In one of the core insert, before bending over
the fingers 2, an eye-plate P¹ between the insulating washer and the ring of
insulating material, which forms an attachment for the lever L, as shown in
Figs. 1 and 2.
The core thus described is quickly and easily assembled, and when so assembled
is as strong as if made in one piece, so far as any strain in action is concerned.
The operation of the lamp is as follows: The carbons K', K are in contact, and
when the current is turned on, the series coil becomes energized and draws up

page_text: core I. This raises the tripping lever L' and puts pawl e and wheel W' into.
engagement locking the wheel work in position. The further movement of the
core then so far extends the spring Z that the frame F is lifted, and as the
wheel W and pinion h are locked, the rack-rod and upper carbon are lifted, and
the arc is struck. The dash-pot D insures the simple and gradual separation of
the carbons by its attachment to the frame F, while the strength of the series coil C
and the adjustment of the springs, determine the length of the arc. As the
resistance of the arc increases by the consumption of the carbon, the current passing
through the series coil is diminished, and the core I begins to descend; the lever L.
is first pushed down by the descent of the core 1, and its further end raises the
lever L. carrying the pawl e, allowing one or more teeth of the wheel W* to
escape, and permitting the carbon to feed; if there is a slight overfeeding,
diminishing the resistance, the series coil is strengthened, and the upper carbon is
lifted slightly to establish the proper length of arc.
The feeding action of the lamp, when property adjusted, is very delicate and.
precise, so that the normal length of arc is maintained and uniform intensity of
illumination secured.
Many changes might be made in the general arrangement of the parts necessary
in the construction of my invention. The action of the springs might be reversed
or the path of the current might be changed, if desired, or a different form of dash-
pot or of the core substituted without affecting the operation of the lamp as a
whole; and all such modifications we aim to embrace.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electric lamp, a controlling and feed regulating magnet, in combination
with means for putting into and out of action an escapement on the feed gearing,.
in response to the minor movements of said electro-magnetic controlling device,
and connections from said controlling device to the frame whereby the feed
mechanism is raised and lowered to regulate the length of the arc by the greater
movements of the controlling device independently of the feeding movement.
2. In an electric lamp a feed carrying train or support attached elastically to
the core or armature of the electro-magnet, said feed controlling frame being
pivotted at a point which permits the raising or lowering of the carbon rod or
holder by the movements of said frame, a direct connection from said controlling
core to a movable escapement is adjusted automatically with relation to the feed
wheel from the position of entire engagement and cessation of feeding to the
position of entire clearance and free feeding, on movements of said core or armature
to its extreme positions, and whereby in the intermediate positions and slight move-
ments of said core such movements may determine the feeding of the teeth of the.
gear individually by the escapement.
3. The method of regulating an electric arc lamp, which consists in operating
the feed mechanism by the movement of the core or armature of the magnet coil
and by further movements thereof adjusting the length of the arc, substantially as
described.
4. In an electric arc lamp and in combination, a series coil, a core therefor, a
frame carrying gearing connected to such core, an escapement for such gearing,.
and means adapted to release the escapement when the current in the series
coil diminishes, and to cause it to re-engage when the length of the arc is
adjusted.
5. In an electric are lamp and in combination, a series coil, a core therefor, a
frame connected to the core and carrying feeding mechanism provided with an
escapement, a rack-rod for the carbon meshing with the feeding mechanism, and a.
lever also connected to the core of the coil and controlling the escapement, whereby
a slight movement of the core operates the feed mechanism, and a movement of:
greater extent adjusts the length of the arc.

page_text: 6. In an electric arc lamp, a series coil, a core therefor, a frame carrying the
gearing and connected to the core, an escapement for the gearing,
a lever con-
nected to the core, and a second lever actuated by the first and controlling the
escapement, whereby the feed and the length of are are controlled entirely by the
series coil.
7. In an electric arc lamp, a series coil, a core therefor, a lever connected to
the core, a frame carrying gearing having an escapement, a second lever actuated
by the first and controlling the escapement, and a spring, as Z, permitting a slight
lost motion between the frame and the first lever, substantially as described.
8. In an electric are lamp, a series coil, a core therefor, a lever connected to the
core, a frame carrying gearing having an escapement, a second lever actuated by
the first and controlling the escapement, a spring, as Z, permitting a slight lost
motion between the frame and the first lever, and a dash-pot connected to the
frame, substantially as described.
9. In an electric are lamp, a dash-pot composed of the following elements: A
cylindrical case closed at both ends, a piston reciprocating therein, and a lateral
attachment to the piston engaging with a frame carrying the feed mechanism.
10. In an electric arc lamp, a dash-pot comprising a cylinder, as D, a second
cylinder within the first and acting as a piston, as P2, the two cylinders provided
with registering slots n and a pin q' extending through the piston and arranged to
form an attachment for the feeding mechanism of the lamp.
11. In an electric arc lamp, a core for the series coil composed of a wire bundle
or body of laminæ of magnetic material enclosed in and sustained by a split casing
of sheet metal, having slots additional to those which split the casing, such slots
running for only a part of the length thereof and being adapted to prevent the
circulation of eddy currents.
12. In an electric arc lamp, a core for the series coil composed of a body of
subdivided magnetic material having an insulating washer upon each end, and
wrapped in insulating material, an insulating ring over each washer and a sheathing
of iron having its ends crimped over the insulating rings and itself slotted to
prevent the circulation of eddy currents.
13. In an electric arc lamp, a core for the series coil composed of a body of
subdivided magnetic material having an insulating washer upon each end and
wrapped in insulating material, an insulating ring over each washer, and a sheathing
of sheet-iron having its ends crimped over the insulating rings and itself slotted to
prevent the circulation of eddy currents, and an eye-plate, as P1, secured in one
end of the core between the insulating washer and the insulating ring.
Dated this 10th day of July 1895