Improvements in Arc Lamps.
Year: 1888

page_text: Date of Application, 9th Nov., 1888
Complete Specification Left. 12th Aug. 1889-Accepted. 21st Sept., 1889
PROVISIONAL SPECIFICATION.
Improvements in Arc Lamps.
I, CHARLES EUGEN LANCELOT BROWN, of The Maschinenfabrik, Oerlikon, near
Zurich, Switzerland, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:-
My invention relates to improvements in Arc lamps and relates more especially to
those of the kind that are worked in single parallel across mains where the EM F is
maintained approximately constant. In working are lamps in parallel it has hitherto
been found necessary to employ an auxiliary resistance in series with the are and the
current which can pass through the lamp will depend on the sum of the resistances of
the arc and the fixed resistance. When the latter is increased the current is rendered
more independent of the resistance of the are so that the merit of the lamp as a
regulator may be estimated by the amount of resistance it is found necessary to use
before it regulates effectively. Besides being an initial expense, these resistances
absorb from one third to one fourth of the work of the dynamo without giving any
useful return in light, the electricity being reconverted into heat and becoming a
source of danger and annoyance. My improvements have resulted in the suppression
of this extra resistance and a lamp constructed according to my invention will maintain
an are of extreme steadiness across a circuit of 50 volts without any auxiliary
resistance. This result has been obtained by employing a much larger proportion of
energy, than has heretofore been usual in the regulating coil, and by making the
whole lamp of extreme simplicity. My invention has also for object to place in the
hands of the public a lamp which shall contain no delicately made parts, adjustable
springs, or anything liable to change or deteriorate, and which when once regulated
by being wound with the proper size and quantity of wire cannot afterwards be
changed. In an are lamp according to my invention a powerful solenoid is employed
having an iron core capable of two movements, one in the direction of its axis, and
the other perpendicular to it, and making electro magnetic contact with one or more
soft iron wheels or discs carrying a toothed wheel that gears into the upper carbon
rod or holder. A suitable construction of arc lamp according to this invention is as
follows:-
Inside a large and powerful vertical solenoid is arranged a heavy iron core free to
move within a cylinder of suitable material such as brass which forms an air dash pot.
This cylinder is suspended from a projection over the solenoid and is free to oscillate
in one direction. The iron core terminates at its lower end in a broad flattened
extremity. The upper carbon holder is geared into a toothed wheel which has a large
and broad iron wheel attached to it on either side. The lower carbon is fixed and the
upper one falls on to it hy gravity when no current passes through the solenoid.
The position of the iron core is such that when it is vertical the flattened lower
surface of the core is a millimetre or two away from the outer edges of the two iron
wheels. To the said flattened surface is soldered or otherwise secured a thin plate of
non magnetic material such as brass that is thicker at its upper than at its lower
extremity, or wedge shaped. The action of the lamp is as follows:-When a current
passes through the solenoid, the iron core becomes magnetised and attracted to the
surface of the iron wheels, and at the same time becomes sucked up into the
solenoid, the upward movement lifting the carbon rod and striking the arc.
When the carbons have burnt away sufficiently to reduce the current, the core
slowly descends and the carbons approach one another. At the same time that the
core descends, its magnetism diminishes, and when it has reached about the middle
position of its vertical movement the weight of the carbon rod opposing the diminished
magnetic attraction (which also acts through a greater thickness of the wedge shaped
plate) causes the iron wheels to slip round a millimetre or two on the surface of the
iron core

page_text: In practice the lamp is found to regulate with remarkable accuracy.
It will be seen that the slip takes place when the solenoid core is in such a position
that it is always capable of an upward movement in case the slip should be too far,
and it is the certainty that the carbons can never fall together and remain in contact
that makes it possible to work without extra resistance. It will be obvious that a
lamp constructed according to this invention can be modified in various ways thus,
two cores instead of one or one iron wheel instead of two may be used; also that it
may be wound differentially or be constructed to keep the position of the focus
constant, without departing from the nature of the invention.
Dated this 9th day of November 1888.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Arc Lamps.
I, CHARLES EUGEN LANCELOT BROWN, of the Maschinenfabrik, Oerlikon, near
Zurich, Switzerland, 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:-
My invention relates to improvements in Are Lamps and relates more especially
to those of the kind that are worked in single parallel across mains where the E.M.F.
is maintained approximately constant.
In working are lamps in parallel it has hitherto usually been found necessary
to employ an auxiliary resistance in series with the are, and the current that
could pass through the lamp has depended on the sum of the resistances of the
are and the fixed resistance. The more the latter is increased the more the current
is rendered more independent of the resistance of the are so that the merit of the
lamp as a regulator could be estimated by the amount of resistance it was found
necessary to use before it regulated effectively. Besides being an initial expense,
these resistances absorb from one third to one fourth of the work of the dynamo
without giving any useful return in light, the electricity being reconverted into
heat and becoming a source of danger and annoyance.
Now my improvements enable me to suppress this extra resistance: a lamp
constructed according to my invention will maintain an are of extreme steadiness
across a circuit of 50 volts without any auxiliary resistance. This result I obtain
chiefly by employing a much larger proportion of energy than has heretofore been
usual in the regulating coil in order that the self induction of the coil should be
large enough to keep the current through the are steady, the self induction tending
to steady the current in the same way that a heavy fly wheel tends to keep the
speed of an engine constant. The whole lamp is made extremely simple in con-
struction, it being an object of this invention to place in the hands of the public
a lamp which shall contain no delicately made parts, adjustable springs, or other
mechanism liable to change or deteriorate, but which, when once regulated, by
being wound with the proper size and quantity of wire, cannot afterwards be
changed.
In an are lamp according to my invention a powerful solenoid is employed,
having an iron core capable of two movements viz., one in the direction of its
axis or vertical, and the other perpendicular or approximately so to it, and making
electro magnetic contact with one or more soft iron wheels or discs carrying a
toothed wheel that gears into the upper carbon rod or holder.
In the accompanying drawings,
Fig. 1 is a vertical section partly in elevation of an arc lamp constructed according
to this invention.
Fig. 2 is a vertical section taken in a plane at right angles to Fig. 1.
Figs. 3 and 4 are horizontal sections taken in the lines A-B and C-D respectively
of Fi

page_text: 1. is a large and powerful vertical solenoid placed in the main circuit of the lamp.
Within it is arranged a heavy iron core 2, free to move within a cylinder 3 of suitable
material such as brass, which forms an air dash pot. This cylinder is suspended from
a bracket 4 secured upon the solenoid, and is free to oscillate in one direction, so that
the core may have a lateral movement as well as a vertical movement. The iron core
terminates at its lower end in a broad flattened portion 5. To this flattened portion
is soldered or otherwise secured a thin plate 6 of non-magnetic material, such as brass,
which is thicker at its upper end than at its lower end, that is to say, it is of wedge
shape in vertical section (see detail Fig. 5). The upper carbon holder 7 is provided
with a rack 8 that gears into a toothed pinion 9 fixed upon a spindle 10 that can turn
in bearings in plates 11 carried by the frame of the lamp. 12, 12, are iron wheels or
rollers fixed upon the spindle 10 at opposite sides of the pinion 9. 13 is a contact
roller carried by a spring arm 14, and arranged to bear against the upper carbon
holder 7. The lower carbon is fixed, and the upper one falls on to it by gravity when
no current passes through the solenoid. The position of the iron core 3 is such that
when it is vertical the surface of its flattened lower portion 5 is a millimetre or two
away from the peripheries of the two iron wheels 12."
The action of the lamp is as follows:-
:-
When a current passes through the solenoid 1, the iron core 2 becomes magnetised
and attracted to the peripheries of the iron wheels 12, and at the same time is sucked up
into the solenoid, its upward movement being transmitted through the wheels 12 and
pinion 9 so as to lift the carbon rod 7 and strike the arc. When the carbons have
burnt away sufficiently to sensibly reduce the current, the core slowly descends and
the carbons approach one another. At the same time that the core descends, its
magnetism diminishes, and when it has reached about the middle position of its
vertical movement, the weight of the carbon rod, opposing the diminished magnetic
action, (which also acts through a greater thickness of the wedge shaped plate 6)
causes the iron wheels 12 to slip round a millimetre or two on the surface of the said
plate 6. In practice, the lamp is found to regulate with remarkable accuracy. It
will be seen that the slip takes place when the solenoid core 2 is in such a position
that it is always capable of an upward movement in case the slip should be excessivo.
It is by the use of an arrangement such as to ensure that the carbons shall never fall
together and remain in contact, in conjunction with the regulating action due to the
self-induction of the solenoid coil, that I am enabled to work my lamp without extra
resistance.
It will be obvious that a lamp constructed according to this invention can be
modified in various ways without departing from the nature of the invention; thus
two iron cores can be used instead of one; or one iron wheel instead of two may be
used; also the solenoid may be wound differentially or the lamp bo constructed to
keep the position of the focus constant.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed declare that what I
claim is :-
1. In an are lamp the combination of a solenoid or regulating coil having a large
self-inductive action, an iron core adapted to move in two directions and one or more
soft iron wheels or masses upon which the said core is held by magnetic attraction,
the arrangement being such that the said wheel or wheels or mass or masses will
automatically control the position of one of the carbon rods or holders..
2. In an are lamp such as referred to in the preceding claim, providing the iron
core with a wedge shaped plate of non-magnetic material such as brass interposed
between the core and the iron wheel or mass, (or wheels or masses).
3. My improved are lamp as described with reference to the drawings annexed.
C. E. L. BROWN.