Improvements in Electromagnetic Solenoid Apparatus.
Year: 1892

page_text: Date of Application, 7th Mar., 1892
Complete Specification' Left, 7th Dec., 1892-Accented. 25th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Electromagnetic Solenoid Apparatus.
I, FREDERIK VILHELM ANDERSEN of 14 Westdown Road, Catford Bridge
in the County of Kent, Electrical Engineer, do hereby declare the nature of this
invention to be as follows:―
Hitherto an electromagnetic solenoid apparatus has consisted of a helix or spiral
of an insulated electric conductor and a movable ordinarily straight iron core, the
working being obtained by passing an electric current through the helical conductor
and arranging the core in such a way that it could travel to the desired extent within
the helix and so perform its work. It has been a great difficulty for many purposes
that the pull obtained is far from uniform through any considerable range of
travel of the core within the helix, such pull diminishing rapidly as that pole of
the core which is inside the helix during its travel approaches either end
of the same.
Another disadvantage in connection with the hitherto known
forms of electromagnetic solenoid apparatus is that it is uneconomical in its
construction as well as in its working by reason of the fact that the path of the
magnetic lines of force through the air is necessarily of a very great length,
extending practically from end to end of the core.
In my improved solenoid apparatus the core is bent back upon itself from its
centre and the solenoid or helix finds its place between the two limbs of the core,
thus the electromagnetic lines of force have a length in air which is equal to the
distance between these two limbs only, and consequently an almost uniform or only
slightly increasing pull is obtained on the core during the greater part of its travel
inside and outside the solenoid, and moreover great economy is gained in so far as
the same amount of conductor and iron in the new form according to my present
invention affords an apparatus capable of a considerably greater performance than
that same amount of material affords in the hitherto known designs.
A convenient form of the core in my new apparatus is to use one limb inside
the other, the outside taking the form of a hollow cylinder, the two limbs being
connected together with an iron flange at one end but having their other two ends
free and leaving a cylindrical space between them in which a helical conductor
which is fixed on its own independent frame finds its place.
This apparatus is applicable to many branches of electrical engineering such as,
for instance, arc lamps, when it is used for regulating the position of the carbons,
electrical governors where it operates either the gear of the steam engine valve or
a multipolar switch controlling an adjustable resistance or any other arrangement
where it is important to obtain a nearly uniform electromagnetic pull through a
relatively considerable distance.
Dated this 7th day of March 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Electromagnetic Solenoid Apparatus.
1, FREDERIK VILHELM ANDERSEN, Electrical Engineer, of 14 Westdown
Road, Catford Bridge, in the County of Kent, 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 for improvements in electromagnetic solenoid apparatus has for

page_text: its object to provide an improved solenoid for use in electric are lamps, which shall
thereby be simple in construction, not liable to get out of order and maintain a
perfectly steady light; and consists essentially in an improved form of core for
the solenoid by which the arc is maintained and regulated in combination with the
devices through which the said core is connected to the carbon holders and which
are efficiently and economically operated by the said solenoid and core.
The core
is so formed that in addition to the usual part inside the solenoid it is provided
with a limb passing in close proximity to the outside of the solenoid. A convenient
form of core consists of a hollow iron cylinder surrounding the solenoid connected
at one end by an iron cap to the usual iron bar passing within the solenoid. The
electromagnetic lines of force of this solenoid have a length in air which is equal
to the distance between these two limbs only and consequently an almost uniform
or only slightly increasing pull is obtained on the core during the greater part of
its travel inside and outside the solenoid and thus render it specially suitable for use
in arc lamps; and moreover great economy is gained both in space occupied and
energy consumed.
:-
In the accompanying sheet of illustrative drawings
Figure 1 is a plan of an electric arc lamp provided with a solenoid apparatus
constructed according to this invention.
Figures 2 and 3 are sectional elevations on the lines A B and C D respectively,
Figure 1, of the same.
Figures 4 and 5 are sections of the positive and negative terminals respectively
of the lamp.
Figure 6 is a plan of the travelling plate of the negative frame.
Figure 7 is a plan of the lower plate of the main frame of the lamp.
Figure 8 is a plan of the gallery carrying the globe.
Figure 9 is a section of the negative carbon holder.
Figure 10 is a similar view to Figure 2 showing a slightly modified construction
of electric arc lamp and
Figure 11 is an elevation of a carbon holder.
The main frame of the lamp consists of the top plate a and bottom plate b which
are held rigidly together by the rods c and the nuts d. The main working parts
are enclosed in a protective cylindrical casing e and the lamp is suspended from
an eye-bolt secured to the top plate a by a pin g. A small gallery attached
to the bottom plate by means of the two pillars carries the globe which is
secured by the three screws m.
is
A cylindrical tube n is rigidly connected to the plate a by means of the flange p
and has firmly fixed upon it the two coil flanges between which is wound the
insulated wire of the solenoid s. The core of the solenoids consists of the inner iron
rod t of the outer iron cylinder u and of the iron head a connecting the lower ends
of the rod and cylinder u rigidly together. One end y of the solenoid sis
connected to the insulated negative terminal N of the lamp and the other end
connected by a flexible insulated wire aa carried down along and stayed to one of
the rods to the negative carbon holder ab. The negative carbon holder ab is
carried by two metal rods ac firmly fixed to a travelling plate ae and guided in the
clearance slots af in the lower plate b. A clearance slot ag is made for the wire aa
in the plate ae behind one of the rods e in order that this plate may travel freely
up and down without rubbing on the wire. It also passes through the insulating
bush ad in the plate b. The negative carbon holder ab is insulated from the rods ac
by means of the fibre bushes ah and fibre washers ai.
One
The travelling plate ae is freely suspended from the two ends of a cord al which
passes over the two pullies am and at its centre through a small eyelet bolt an fixed
in the upper end of the iron core t of the solenoid s. The positive carbon holder ao
is pinned on to the projecting part of the lower end of the iron core t.
pulley am is milled on to the outer periphery and a pawl ap-pivotted between
small projections from the top plate a acting on the milled pulley serves to prevent
the pulleys from revolving in an outward direction, or both pullies may be milled

page_text: and each have its own pawl. The positive terminal P of the lamp is connected to
the metallic frame and the flexible conducting wire at connects the frame with a
metal ring au fixed on the cylindrical core u. The lamp is shown in the normal
position, that is when no current is passing through it, when the excess of weight
of the iron cores tand and of the upper holder ao and carbon ar above the weight
of the negative frame holder and carbon, causes the two carbons to come into contact
with one another.
The working of the lamp is as follows:-When a current enters the lamp
through the positive terminal P which is directly connected with the metal frame,
it passes through the flexible connecting wire at, the ring au, the iron cylinder u,
to the positive carbon ar and through the carbons which are in contact with one
another; the circuit being completed through the wire aa, the solenoid a, the wire y,
to the negative terminal N. The iron core t, u of the solenoid is raised by the
force produced on the iron core by the current in the solenoid and raises the positive
carbon ar, the cord slipping in the grooves of the pulleys an which are prevented
from rotating by the pawl ap. The negative carbon is simultaneously lowered.
Thus the two carbons are parted and the are formed between them. The relative
weights of the negative frame and the iron core with the positive carbon holder are.
so adjusted that the force exerted by the solenoid on its core due to the current
with which the lamp is intended to work, balances the difference of weight between
them. The arc will remain of such a length that this current is maintained
provided the electric circuit in which the lamp works is so arranged that a difference
in the length of the arc causes a sensible difference in the strength of the current.
In addition to the winding already described a shunt of fine wire and high
resistance, the ends of which are directly connected with the terminals of the
lamp, is sometimes wound on the solenoids in such a manner that the electro
magnetic force due to this shunt is opposed to the force due to the series wire and
when the lamp is working normally is smaller in amount than the latter thus
making the lamp differential.
In the modification shown in Figure 10 the iron core of the solenoid is rigidly
attached to the travelling plate ae carrying the negative carbon holder ab and the
centre of the cord al. is connected to an independent tube a carrying the positive
carbon holder ao and passing through the centre of the core which in this case is
made hollow. In this arrangement the negative frame and carbon is heavier than
the positive carbon and tube and consequently when no current is on the lamp the
two carbons are held apart by gravity. Also when fresh carbons have been.*
inserted, the core and solenoid are in their extended position and as the carbons
consume the solenoid becomes gradually enclosed in the core. In this case there
are two pawls ap bearing on the pulleys am and they are also provided with slightly
elongated centre holes which regulate the distance which the points of the carbons
separate when no current is passing through the lamp. The cord is arranged to
have sufficient frictional resistance to prevent the carbons from dropping further
apart. The solenoid is arranged in a shunt circuit and when the proper electro-
motive force is switched on to the lamp the action of this shunt on the iron core is
to make the carbons approach and touch each other. The main current then
passes through the carbons and thus the power of the solenoid is decreased and the
excess weight of the lower frame and carbon causes the carbons to fall apart to the
extent of the proper length of an arc which is maintained during the burning,
the power of the shunt when excited by the normal working electromotive force
being so arranged as to just balance the excess of weight of the negative frame and
the iron core over that of the positive rod and carbon. The elongated holes in the
pawls ap determine the length of the arc. A negative series winding, that is a
comparatively small number of turns of stout wire connected in series with the
main current through the lamp, is sometimes wound on the solenoid in such a
manner as to weaken the effect of the current in the shunt. This negative series
winding materially assists in damping the unsteadiness which is likely to occur in

page_text: cases where the lamp is required to burn in circuits which contain only a small
amount of resistance.
As special means of damping, the solenoid tube n is made of a highly conducting
copper. A certain amount of damping effect is also obtained from the travelling
plate ae which is arranged to have as large a surface against the air at right angles
to the motion as possible.
When the lamp is made for alternating currents, the iron core t is constructed of
fine iron wire, the tube n is made of insulating material such as glass ebonite or
vulcanized fibre and the series wire is a finely laminated conductor so as to avoid
heating by eddy currents.
The carbon holder ao is constructed so that it enters the tube ax. A small
tongue ay is formed on its side and a projection az is formed on the free end of
the tongue so that as the holder is screwed into the end of the tube ax, the
projection comes into contact with the tube and forces the tongue inwards to grip
the carbon...
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. The construction and arrangement of solenoid and core for maintaining and
regulating in combination with devices for connecting the carbon holders to the
solenoid core the arc of electric are lamps substantially as described.
2. The construction and arrangement of solenoid and core substantially as
described for maintaining and regulating in combination with the devices for con-
necting the carbon holders to the solenoid core the arc of electric arc lamps and
wound with series and shunt wires in such manner that the series wire normally
during the working of the lamp partially neutralises the shunt wire.
3. The solenoid and core arranged and constructed substantially as described with
reference to the drawings for use in electric arc lamps.
Dated this 7th day of December 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.