Improvements in and relating to Electric Arc Lamps.
Year: 1892

page_text: Date of Application, 11th Oct., 1892-Accepted, 19th Nov., 1892
Improvements in and relating to Electric Arc Lamps.
I, WILHELM MATHIESEN, Blumengasse I, Leipzig, in the German Empire,
Manufacturer, 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 :-
This invention relates to electric are lamps and more especially to that class of
lamp furnished with only one electro magnet which is included in a shunt circuit
and effects the striking and subsequent regulation of the arc.
Referring to the accompanying drawings
Figure 1 diagrammatically illustrates the lamp when the electro magnet is
inoperative and
Figure 2 illustrates the positions of the various parts when the magnet operates
and brings the carbons nearer together.
If the current be turned on while the carbons are separated by too great a
distance to allow an arc to be formed, the electro magnet coil b is energised and its
pole piece g attracts the armature a. The frame e in which the train of wheels is
mounted is attached to the supports 9 of the armature a and consequently moves
with it around the pivot f. The fan is consequently moved from out of contact
with the stop c and consequently leaves the train of wheels free to rotate upon the
descent of the upper carbon. This motion is imparted to them as shewn by a cord
or chain which passes over the lower wheel p and suspends the lower carbon.
The carbons thus approach each other and rotate the wheels owing to the superior
weight of the upper carbon. Upon the carbons meeting the current ceases to flow
through the coil and the armature a is pulled back by the spring d. The carbons
are separated owing to the motion thus given to the wheel p and the arc is struck,
the wheel train being again locked by the fan f and the stop c. The armature
assumes a position of equilibrium and is alternately pulled by the spring d or the
magnet as the arc lengthens and then diminishes.
As is already shewn in the drawings the pivot on which the wheel frame and
the armatures swing is not in a line with the axis of the wheel p but at one side
so as to cause this wheel to act upon the carbon suspending cord as a lever with
unequal arms of the proportions of four to nine. These proportions indicate the
relative weights of the carbons necessary to employ with continuous currents the
heavier upper carbon 9 being suspended from the short arm 4 and the lighter lower
carbon 4 being suspended from the arm 9 (see Figure 2). The two carbons are
thus always in a state of equilibrium and cannot possibly by any difference of
weight, affect the position of the armature a.
The pole piece 9 of the electro magnet is furnished with an extension h by
means of which the armature is attracted more strongly but is not released until
the arc is properly formed.
To prevent all possibility of a wing of the fan engaging with the catch e
during the time the train of wheels should be rotating, this catch is formed upon
an angle piece K which is pivoted at 7 as is more clearly shewn in Figure 4, so as
to be capable of swinging under the influence of a spring out of the path of the
fan f. The movement of the angle piece K is limited in either direction by the
projection n and the stop m.
In are lamps of ordinary construction the extra resistance set up owing to the
heating of the coil by the passage of the current, and the heating of the lamp
generally by transmitted heat from the arc itself, often necessitates an increase in

page_text: the electro motive force of five or six volts. In a lamp constructed according to
this invention the heat operates to additionally regulate the arc and keep the electro
motive force constant.
This is accomplished in one form by the employment of an expansion strip i the
lower end being secured to the lamp body and the armature spring & being
attached to its upper free end. This strip is formed of two thinner metal strips
having different co-efficients of expansion and is straight at the normal temperature.
Upon the temperature rising the strip bends as shewn in Figure 2 and diminishes
the tension upon the spring d and thus allows the armature a to be more easily
attracted.
Different forms of the compensated expanding body are shewn in the Figures 5
to 12.
As illustrated in Figure 5 the outside bent strips s have high and the inner
straight strips low expansive co-efficients.
Figures 6 and 64 illustrate in a slightly modified form the strip already illustrated
by Figures 1 and 2.
In Figure 7 the copper or brass rod t is pivoted and secured at its lower end
to the iron one over which the additional coil is placed in a shunt to increase
the heating. The linear expansion and contraction of the rod u are transmitted as
indicated by the arrows.
In Figure 8 a vessel w is pivoted on the same pivot as the armature support q
and the wheel frame and is in communication with a second vessel which contains
any liquid displaced from the first by expansion and alters the centre of gravity of
the swinging wheel frame.
In Figure 9 a vessel w containing a suitable liquid is closed by a flexible
diaphragm the movement of which is transmitted by rods u and t to the
spring d.
Another means by which the same result may be attained is illustrated in
Figure 10 where the armature supports are formed of three strips rst which by
unequal expansion alter the distance between the armature a and the pole pieces of
the electro magnet.
In Figure 11 the compensated spiral y carries a weight g' which moves and alters
the centre of gravity of the wheel frame and armature.
In Figure 12 a secondary armature a¹ is shewn pivoted at t and moved by
expansion so as to direct more or fewer magnetic lines of force to the main
armature a.
Figure 3 illustrates a differential lamp constructed to embody these improve-
ments the armature and pole pieces being substituted by the usual coils and
solenoid.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is,―
1. The combination with a continuous current arc lamp of mechanism for
compensating the different weights of the carbons, constructed and arranged
substantially as herein before described and as illustrated by the accompanying
drawings.
2. In an arc lamp of the class herein before described the combination with the
electro magnet pole pieces of lateral wings or projections substantially as and for
the purpose hereinbefore described and as illustrated by the accompanying
drawings.
3. The combination with an arc lamp of a movable catch by means of which
the wheels are either released or held, constructed and arranged substantially as
herein before described and as illustrated by the accompanying drawings.
4. In an arc lamp constructed with a shunt coil the combination and arrange-
ment of an expanding strip or body by means of which the arc is additionally

page_text: regulated substantially as hereinbefore described and as illustrated by the accom-
panying drawings.
5. An arc lamp constructed and arranged substantially as hereinbefore described
and as illustrated by the accompanying drawings.
Dated this 10th day of October A.D. 1892.
WILLIAM E. HEYS,
Agent for the Applicant.