Improvements in Electric Arc Lamps.
Year: 1896

page_text: Date of Application, 11th Dec., 1896
Complete Specification Left, 29th Sept., 1897-Accepted, 11th Dec., 1897
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps.
I, EMIL HUNGERBUHLER, of 17 Whittingstall Road, Fulham, in the County
of London, Electrical Engineer, do hereby declare the nature of this invention
to be as follows;-
This invention relates to that class of electric arc lamps in which the feed
of the carbons is automatically regulated by means of a solenoid or
solenoids having a specially shaped core.
pair of
Our improvements have for their object, firstly to equalise the pull of the
solenoid on the core, so as to keep the same approximately constant for the
whole range of the feed motion corresponding to the length of the carbons,
and secondly, to simplify the general construction of the lamp.
Instead of using a cylindrical regulating coil and a conical core adapted to
move in a straight line, as the case in the well-known Pilsen lamp, we make
the axis of the solenoid, as well as the outline of the core, circular, and mount
the core in such a manner, that the magnetic effect of the solenoid will cause
it to turn on the axis of the circle of which the core form an arc.
The core is adapted to project over both ends of the solenoid and occupies
the major portion of its circle, while the remainder is formed by the frame which
supports the. core and connects it with a horizontal axle coinciding with the
axis of the said circle.
The core is laminated and not of uniform thickness, being thick at the ends,
and thin at or near the middle of its length.
The movable core, together with its supporting frame, is adapted to serve as
a rope pulley from which the two carbon rods are suspended by a
metallic cords.
pair of
Instead of using the movable core as part of the rope pulley, a separate pulley
may, however, be mounted on the axle parallel to the movable core, and 'the
movable core, together with the pulley and the parts attached to the same,
may be balanced by a weighted lever mounted on the axle of the core.
The cords serving to suspend the carbons are preferably utilised also for con-
ducting the electric current to the same, in which case they are protected and
guided by passing axially down a pair of slotted vertical tubes.
Each of the two carbon holders is supported by a horizontal cross bar which
extends from one of the said vertical guide tubes to the other and is guided
in the slots of the same. Each cross bar is connected with the lower end of one
of the said flexible metallic cords attached to the pulley.
The winding of the solenoids may be in series, or in shunt, or differential, as
is the case with other arc lamps.
A pair of regulating coils and movable cores may be placed side by side, the
cores being mounted on the same axle and acting in opposition to each other,
one of the coils being placed in series with the lamp circuit, while the other
forms a shunt.

page_text: To prevent violent oscillation and a rush of current at the time of striking
the arc, a dash pot is sometimes used, but we prefer to employ a controlling
weight suspended from an extension of the positive carbon holder by means of a
helically coiled spring. If now the positive carbon is suddenly drawn upward,
the mass of the controlling weight acts as a dynamic resistance serving to stretch
the spring and to retard the upward motion of the carbon. Instead of such a
weight, a controlling spring may be used, for instance in lamps having horizontally
movable carbons.
Dated this 11th. day of December. 1896.
FAIRFAX & WETTER
Agents, 433, Strand, London.
COMPLETE SPECIF
Improvements in Electric Arc Lamps.
I, EMIL HUNGERBÜHLER, of 17, Whittingstall Road, Fulham, in the County
of London, Electrical Engineer, 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 that class of electric arc lamps in which the feed
of the carbons is automatically regulated by means of a solenoid or pair of
solenoids having a specially shaped core.
My improvements have for their object, firstly to so regulate the pull of the
solenoid on the core, that it remains approximately constant for the whole range
of the feed motion corresponding to the length of the carbons, except where a variation
is necessary to compensate for the gradual loss of weight of the positive carbon,
and secondly to simplify the general construction of the lamp.
Instead of using a cylindrical regulating coil and a conical core adapted to move
in a straight line, as is the case in the well known Pilsen lamp, I make the axis
of the solenoid, as well as the outline of the core, circular, and mount the core
in such a manner that the magnetic effect of the solenoid will cause it to turn
on the axis of the circle of which the core forms an arc.
The core is adapted to project over both ends of the solenoid and occupies the
major portion of its circle, while the remainder may be formed by the frame which
supports the core and connects it with a horizontal axle coinciding with the centre
or axis of the said circle.
The core is laminated and not of uniform thickness, being thick at the ends,
and thinnest at or near the middle of its length, so as to compensate for the changes
of magnetic effect due to the position of the core, and for the gradual loss of
weight of the positive carbon."
The movable core, together with its supporting frame, may be adapted to serve
as a rope pulley from which the two carbon rods are suspended by a pair of
metallic cords.
Instead of using the movable core as part of the rope pulley, a separate pulley,
may, however, be mounted on the axle paralell to the movable core, and the movable
core, together with the pulley and the parts attached to the same, may be balanced
by a weighted lever mounted on the axle of the core.
The cords serving to suspend the carbons are preferably utilised also for con-
ducting the electric current to the same, in which case they are protected and
guided by passing axially down a pair of slotted vertical tubes.
Each of the two carbon holders is supported by a horizontal cross bar which
extends from one of the said vertical guide tubes to the other, and is guided in

page_text: the slots of the same. Each cross bar is connected with the lower end of one of
the said flexible metallic cords attached to the pulley.
The winding of the solenoids may be in series, or in shunt, or differential, as
is the case with other arc lamps.
A pair of regulating coils and movable cores may be placed side by side, the
cores being mounted on the same axle and acting in opposition to each other, one
of the coils being placed in series with the lamp circuit, while the other forms
a shunt.
In the accompanying drawings Fig. 1 is a sectional elevation of an arc lamp
embodying my invention, Fig. 2 is a side view of the regulating apparatus, Fig. 3
is a plan of the same, Fig. 4 is a separate view of the core, Fig. 5 is a diagram
of forces. For the sake of clearness the standard G is not shown in Fig. 1. A is
the positive and A' the negative carbon, B, B are the horizontal crossbars, C, C
are wire ropes for suspending the carbon holders, D) is the pulley, to which the
ropes are attached by means of screws, as shown in Fig. 1, E, are a pair of
specially shaped solenoid cores connected with each other, and with the rope pulley
by a yoke d, as shown in Fig. 2. Between the position of the cores in Fig. 1 and
that in Fig..2 there is a difference of about 90°, the yoke d being in Fig. 2 at
the top, while in Fig. 1 it is approximately level with the axis of the cores.
pulley D carrying the circularly curved cores E E is mounted on a horizontal
shaft F which is held between the points of a pair of screws fixed in the stan-
dards G, G. The latter are mounted on the circular frame or baseplate H and
support at the top the terminals I, I', insulated from the stands G.
J, J are two circularly curved solenoids, each of which is mounted in the
centre on the baseplate H, by means of a vertical lug h.
K, K are the vertical guide tubes for the carbon holders or cross bars B, B¹.
They are fixed at the top to the baseplate H and connected at the bottom by a
circular plate L. Each tube has on the inside a longitudinal slot k or for
guiding the respective cross bar B, or B. As shown by Fig. 1 the negative
carbon A is insulated from the lower cross bar B and suspended from the rope K¹
by means of a rod & guided in the tube K' by an insulating roller M. The
positive carbon holder is fixed to the upper cross bar B suspended from the rope C,
and provided with a vertical guide rod b, which carries a guide roller M and a
balance weight N.
O is a balance weight mounted on a lever extending radially from the shaft F.
The said balance weight serves to balance the weight of the cores E, E, pulley D
and yoke d, so that the turning moment of the same plus that of the weight 0 with
regard to the axle F is equal to zero, in every position of the cores.
The solenoid J₁ is series wound, its coil being inserted between the positive
terminal I and the stand G, as indicated by Fig. 2, and the solenoid coil J is
shunt, wound, its coil being inserted between the positive and negative terminals I
and I.
In Fig. 1 one half of the shunt coil J is shown in section, and the other half
in side view. The current flows from the positive terminal I through the wire p
to the series solenoid J, then through the wire g into the standard G, thence
through the baseplate H, standard G and wire r into the axle F, thence through
the pulley D, wire rope C, carbon P, upper cross har B, upper carbon A, lower.
carbon A, lower cross bar B, guide rod 6, wire rope C, and wire a to the negative
terminal I.
To prevent violent oscillation and a rush of current at the time of striking
the are, a dash pot is sometimes used, but I prefer to employ an electro-mechanical
brake adapted to act on the circumference of the rope pulley or of a separate brake
pulley connected with the same and operated by the lamp circuit.
For this purpose the lamp circuit may be led through a solenoid the core of
which is attached to the long arm of a lever carrying on its short. arm a brake
block.
The latter is placed in proximity to the lower part of the rope pulley, or to the

page_text: circumference of a brake pulley, and pressed against the latter, if the exciting
current of the solenoid is strong enough to overcome the pull of a helical spring
acting on the brake block in opposition to the solenoid and tending to keep the
brake block out of contact with the pulley.
Such a brake is indicated in Fig. 1, where T shows the double armed brake-
lever, which has its fulerum in a bracket t mounted on the baseplate H, V shows
the solenoid through which passes the main current on its way to or from the
carbons, and U is the solenoid core attached to the lever T.
If two solenoids are used, as in the example represented by the drawing, the
core of the series solenoid and that of the shunt solenoid, are equal, but placed
in opposite directions (Figs. 2 and 3), so that one core occupies its extreme right
hand position, while the other occupies its extreme left hand position.
If the lamp is designed for alternating currents, or for horizontal carbons, the
core or cores should have such a shape, that the pull of the solenoid or solenoids
will remain constant for the whole range of the feed motion.
If the lamp is designed for continuous currents and vertical carbons, as repre-
sented by Fig. 1, the pull of the solenoid or solenoids on the core or cores should
vary, so as to compensate for the gradual reduction of the surplus weight of the
positive over that of the negative carbon, which surplus has generally a maximum
of about 30 grammes, and the shape of the core or cores should be adjusted, an
as to satisfy this requirement. The necessary adjustment may be ascertained by
experiments or by calculation.
In the diagram Fig. 5 the abscissue represent the feed motion of the carbons,
from 0 to 20 centimeters, and the ordinates the tangential pull of the solenoids
on their respective cores at consecutive stages of the feed motion.
At the beginning of the feed motion, that is, when the carbons have their full
length, the pull of the series coil is equal to 130 grammes and is represented by
the ordinate AB, while the pull of the shunt coil is equal to 51 grammes and
is represented by the ordinate A-B. At the end of the feed motion, the pull
of the series solenoid is represented by the line 1 C and that of the shunt by the
line D C.
The straight line BC represents the theoretical variation of the pull of the series
coil during the whole course of the feed motion, and the curve BC represents the
actual variation ascertained by experiments. The curve B C differs but little
from a straight line paralell to the base line, because the pull of the shunt ceil
remains approximately constant.
As the two solenoids pull in opposite directions, the result is shown by the
differénce between corresponding nilinates, that is, the tangential pull on the cir
cumference of the pulley at the beginning and at the end is shown by the
lines B and C C. At the beginning this difference is balanced partly by the
balance weight N which corresponds to the line B 1, and partly by the surplus
weight of the positive carbon over the negative, which corresponds to the line B B
(30 grammes) at the end there is only the balance weight N which corresponds
to the ordinate C C, to keep the magnetic pull in equilibrium.
Although I prefer to employ uniformly wound solenoids of circular cross section,
as shown, it is evident, that a similar effect may be obtained by solenoids with
oval or other cross section, and with more windings or layers at one end than at
the other, also that the curvature of the cores and of the solenoid axes need not
be exactly circular, and that the cores may be fixed, while the solenoids are
mounted on the pulley axle and adapted to turn with the same.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is;
1. In electric are lamps, an automatic feed or regulating mechanism, com-
prising in its construction a curved solenoid and a circularly curved core adapted
to shift the carbons by turning on its centre of curvature, the thickness or sectional

page_text: area of the said core being unequal and so adjusted as to render the pull of the
solenoid on the core constant during the whole range of the feed motion, or to
compensate for the gradual loss of weight of the positive carbon, substantially
as described.
2. In automatic feed or regulating mechanism for electric arc lamps, the com-
bination of a curved solenoid controlled by the lamp circuit, with a circularly
curved core adapted to turn on the axis of its curvature, a pulley and balance
weight formed on the said core or rigidly connected with the same, and a pair of
ropes or other flexible cords passing over the said pulley, said ropes serving to
suspend the carbons and to conduct current to the same, substantially as described.
3. In automatic feed or regulating mechanism for electric arc lamps, the com-
bination of a pair of circularly curved solenoids one of which is excited by a
series coil and the other by a shunt coil, with a pair of circularly curved cores
mounted on an axie which coincides with their respective centres of curvature, a
pulley mounted on the said axle between the cores, and a pair of ropes passing
over the said pulley and serving to suspend the carbons as well as to conduct
current to the same, substantially as described.
4. In .automatic feed or regulating mechanism for electric are lamps, the com-
bination of a curved solenoid controlled by the lamp circuit, with a circularly
curved core adapted to turn on its axis of curvature, a pulley and a balance weight
formed on or rigidly connected with the said core, a pair of carbon holding ropes
or other flexible cords passing over the said pulley, and an electro-mechanical
brake adapted to act on the circumference of the said pulley or of a separate
brake pulley connected with the same, substantially as described.
5. In electric arc lamps, an automatic feed or regulating device constructed
and adapted to operate substantially as described with reference to the drawing.
Dated this 23rd day of September 1897.
FAIRFAX & WETTER
Agents, 37 and 39, Essex Street, Strand, London.