Improvements in Electric Arc Lamps of the Enclosed Type.
Year: 1897

page_text: Date of Application, 17th Nov., 1897
Complain Cons
Sinn St w0th w
1000
Annantad
2nd Cont 4000
Date of Application, 17th Nov., 1897
Complete Specification Left, 30th July, 1908 Accepted, 3rd Sept, 1808
PROVISIONAL SPECIFICATION.
Improvements in Electric Arc Lamps of the Enclosed Type.
ALBERT LEWIS DAVIS, 23, Alexandra Road, Gipsy Hill, Upper Norwood,
do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in the mechanism of arc lamps of the
enclosed type, and improvements relating to the cover, or gas check, of the
inner globe.
On a suitable baseplate I fix a metal tube of suitable length, & diameter
sufficient to allow the top or positive carbon and holder to freely slide therein;
concentrically with this tube which may serve as a support I fix, at a suitable
height from the baseplate, a solenoid, the iron core of which, is of annular shape
and free to slide vertically upon the outside of the above mentioned supporting
tube. Three metal connecting links are attached to the movable iron core, the
lower ends of these links are pivotally connected to the ends of 3 steel jaws which
are also suitably held in bearings placed at 3 equi-distant points on an annular
ring, concentric with the supporting tube through which passes the positive
carbon rod, in a manner such that the unconnected ends of the jaws pass through
three radial slots of suitable length, cut through the before-mentioned supporting
tube. The ring carrying the three steel jaws is free from contact with all other
parts of the mechanism, but will partake of the vertical motion of the steel jaws
should these be raised or lowered by the action of the solenoid and iron core.
The relative positions of the supporting bearings on the annular ring and the
shape of the steel jaws are such that when the movable iron core is pulled upwards
into the solenoid by the action of the current, the jaws tend to close upon and
grip the carbon rod passing through the central supporting tube, further upward
motion on the part of the movable iron core and jaws will then result in lifting
the top carbon out of contact with the lower carbon; the length of the slots in
the supporting tube will allow of a certain amount of upward or downward
motion, and the iron core and the jaws griping the carbon will be free to descend
together until the ends of the jaws in contact with the carbon rod rest upon the
lower limit of the slots, this arrests further motion of this end of the jaws and
alters the position of the fulcrum about which they have motion, any further
downward motion of the iron core will therefore cause the jaws to recede from
& release their hold upon the carbon rod allowing the latter to slip and come in
contact with the lower or negative carbon.
The lower carbon is enclosed in a glass globe of suitable form and size having
suitable openings at the ends, the lower opening is closed by an asbestos washer,
the top opening is closed by a cap having a hole in the centre to allow the passage
of the top or positive carbon rod. This cap is composed of a substance which
retain heat to a great extent, such for instance as fire clay, pipe clay, steatite,
compressed asbestos or other suitable substance; the object of this special heat

page_text: retaining cap is to render the arc more stable should the inner globe be exposed to
currents of air, thus dispensing with a sealed outer globe, and causing great
steadiness in burning.
Improvements in Electric Arc Lamps of the Enclosed Type.
ALBERT LEWIS DAVIS, 23, Alexandra Road, Gipsy Hill, Upper Norwood,
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 the mechanism of arc lamps of the
enclosed type and improvements relating to the cover or gas check of the
inner globe.
On a suitable base plate I fix a metal tube of suitable length, & diameter
sufficient to allow the top or positive carbon and holder to freely slide therein,
concentrically with this tube which may serve as a support I fix at a suitable
height from the baseplate a solenoid, the iron core of which is of annular shape
and free to slide vertically upon the outside of the above mentioned supporting
tube. Three metal connecting links are attached to the movable iron core, the
lower ends of these links are pivotally connected to the ends of 3 steel jaws which
are also suitably held in bearings placed at 3 equi-distant points on an annular
ring, concentric with the supporting tube through which passes the positive
carbon rod, in a manner such that the unconnected ends of the jaws pass through
three radial slots of suitable length cut through the before-mentioned supporting
tube. The ring carrying the three steel jaws is free from contact with all other
parts of the mechanism, but will partake of the vertical motion of the steel jaws
should these be raised or lowered by the action of the solenoid and iron core.
The relative positions of the supporting bearings on the annular ring and the
shape of the steel jaws are such that when the movable iron core is pulled upwards
into the solenoid by the action of the current, the jaws tend to close upon and
grip the carbon rod passing through the central supporting tube, further upward
motion on the part of the movable iron core and jaws will then result in lifting
the top carbon out of contact with the lower carbon; the length of the slots in
the supporting tube will allow of a certain amount of upward or downward
motion, and the iron core and the jaws griping the carbon will be free to descend
together until the ends of the jaws in contact with the carbon rod rest upon the
lower limit of the slots, this arrests further motion of this end of the jaws and
alters the position of the fulcrum about which they have motion, any further
downward motion of the iron core will therefore cause the jaws to recede from
and release their hold upon the carbon rod allowing the latter to slip and come in
contact with the lower or negative carbon.
The lower carbon is enclosed in a glass globe of suitable form and size having
suitable openings at the ends, the lower opening is closed by an asbestos washer,
the top opening is closed by a cap having a hole in the centre to allow the passage
of the top or positive carbon rod. This cap is composed of a substance which
retains heat to a great extent, such for instance as fire clay, pipe clay, steatite,
compressed asbestos or other suitable substance; the object of this special heat-
retaining cap is to render the arc more stable should the inner globe be exposed to
currents of air, thus dispensing with a sealed outer globe, and causing great
steadiness in burning.

page_text: letter.
Fig. 1 gives a general view of the complete lamp in part section and part
removed.
Fig. 2 gives an enlarged elevational view in part section and part removed of
the movable iron core, connecting links, steel jaws, annular ring and limiting
stops.
Fig. 3 gives a reverse plan of the annular ring, and steel jaws gripping the
carbon rod.
Figs. 4 and 5. give an enlarged half-sectional elevation and plan of the heat-
retaining cap covering the top opening of the inner globe.
In Fig. 1, B is a baseplate supporting a metal tube T of an internal diameter
sufficient to allow of the free movement of the top or positive carbon rod C and
its holder, the latter not shown on the drawing; conveniently attached to this
tube T is a solenoid S Fig. 1 capable of exerting a magnetic pull.
on the movable annular iron
core I. 3 metal connecting links L,
L, L, Figs. 1 to 3 are attached to the movable iron core I, the
lower ends of these links are pivotally connected to the ends of
3 steel jaws J, J, Ju Figs. 1 to 3, these latter are suitably held in bearings
placed at 3 equi-distant points on an annular ring R Figs. 1 to 3, this ring R is
placed concentrically with and outside the tube T in a manner such that the
unconnected ends of the said jaws pass through 3 radial slots K, K', Fig. 1 of
suitable length. The ring R carrying the 3 steel jaws J J¹ J" is free from contact
with all other parts of the mechanism, but will partake of the vertical motion of
the steel jaws should these be raised or lowered by the action of the solenoid S
and iron core I. The relative positions of the supporting bearings on the ring R
and the shape of the jaws J J1 Ju are such that when the movable core I is pulled
upwards into the solenoid S by the action of the current, the jaws tend to close
upon and grip the carbon rod C as shown in Figs. 2 and 3, further upward
motion on the part of the core I and jaws will then result in lifting the top
carbon C out of contact with the lower carbon C¹ Fig. 1.
The length of the slots K, K', in the supporting tube T, Fig. 1, will allow of
a certain amount of upward or downward motion, and the iron core and the jaws
griping the carbon C will be free to descend together until the ends of the
3 jaws
JJ J in contact with the carbon rod C rest upon the 3 lower limits M
of the 3 slots K K', Figs. 1 and 2. The lower limits M of the slots form stops
which arrest further motion of this end of the jaws J J¹ J", and alter the position
of the fulcrum about which they have motion, any further downward motion of
the iron core will therefore cause the jaws to recede from and release their hold
upon the carbon rod C, allowing the latter to slip and come in contact with the
lower or negative carbon rod C as shown in Fig. 1.
The lower carbon C₁ is enclosed in a glass globe G of suitable form and size, hav-
ing openings at the ends, the lower opening is closed by an asbestos washer A, Fig. 1,
or similar device, the top opening is closed by a cap N, Figs. 1, 4, and 5, having
a hole in the centre of suitable size to allow the passage of the top or positive
carbon rod C. This cap N is composed of a substance which retains heat to a
great extent, such for instance as fire clay, pipe clay, steatite, compressed asbestos
or other substance of a like nature; the object of the special heat retaining cap
is to render the arc more stable should the inner globe be exposed to currents of
air, thus dispensing with a sealed outer globe, and causing great steadiness in
burning.
The usual resistance placed in series with the lamp may conveniently be wound
round the outside of the inner mechanism cover, but insulated therefrom by a
sheet of asbestos or other suitable insulator, as shown in section at E Fig. 1.
A second cover E¹ may be placed outside the former in order to protect the
resistance from moisture or other damage, suitable terminal blocks marked +
Fig. 1 serve to convey current to and from the lamp. A dash pot D Fig. 1 of
-

page_text: °
any convenient and suitable type may be provided to guard against any sudden
and violent motion of the iron core I. An unsealed outer globe G¹ Fig. 1 may be
provided to give a better appearance to the lamp and to guard the inner globe
from draughts and exposure to the weather.
Having now described a convenient method of carrying my invention into
practice the action of the lamp when wound with simple series wire on the
solenoid S may be described as follows:
The current will enter the lamp by the terminal marked + passing round the
wire of the solenoid S to the carbon rod C through the carbon C passing up the
supporting frame H from thence through the resistance coils E and out by way of
the terminal marked -, when the above circuit is complete the solenoid becomes
energised above the normal amount and attracts the movable iron core I vertically
upwards, causing the jaws J J1 J1 to grip and lift the carbon C out of contact
with the carbon C¹ thus striking the arc. This upward motion continues until
the normal length of arc is reached, at which point the strength of the solenoid
being reduced by the lessening of the energising current, is now just sufficient
to maintain the movable core I in that position; in proportion
the carbons consume away so the solenoid decreases its pull upon the
core I thus allowing a gradual downward motion of the upper carbon C
in
as
exact proportion to the rate of carbon consumption, this gradual
downward motion continues until the lower limits M of the slots K K' are reached
and the ends of the jaws J J1 J1 being arrested at these points and the down-
ward motion continuing, the jaws are caused to recede from and release their
grip upon the carbon C allowing the latter to slip down towards the carbon C¹ in
proportion to the consumption of carbon. If from any cause the carbon C
should descend too far then the power of the solenoid S being thereby increased
the latter again lifts the core I and therefore the carbon C into a position such
that the normal arc is re-established, when the downward motion continues as
before described until all the carbon is consumed.
If required the mechanism may be adapted for any type of winding, thus a fine
wire winding may be placed on the solenoid S in addition to a simple series
winding, the ends of such fine wire being connected across the two lamp terminals
or the two carbons in a manner such that the energy due to the fine wire winding
tends to neutralise the energy due to the coarse or series windings thus forming
a differential type of regulation.
In like manner the solenoid S may receive a simple shunt winding; this form
of winding requires that the carbons should tend to separate from each other and
remain separated when the lamp is out of circuit. In order to meet this require-
ment the solenoid S and core I must be reversed on the supporting tube T,
3 longer links to replace the 3 short links L L L should be provided being
attached to the top of the movable core I passing vertically downwards outside
the sides of the inverted solenoid S and pivotted to the ends of the 3 steel
jaws J J1 J11
A spring may be conveniently placed in the space under the
end of the movable iron core tending to constantly press the core out of the mouth
of the inverted solenoid S thus causing the core to act in opposition to the attrac-
tive action of the solenoid and causing the carbons to always tend to separate
from each other. The strength of this spring acting in opposition to the pull of
the solenoid should be such that when a normal arc is secured the attractive force
of the solenoid on its movable iron core is exactly balanced by the opposing force.
of the spring. Any abnormal variation of the potential across the arc will then
result in a compensating movement of the core and jaws giving motion to the
carbon rod C.
Having now particularly described and ascertained the nature of my saiu inven-
tion, and in what manner the same is to be performed I declare that what I
claim is:-
(1) In the controlling mechanism of an electric arc lamp the use of three iaws

page_text: pivotal bearings on the said ring. The griping ends of the jaws to point inwards
and the other ends to be coupled by pivotted joints to an electric controlling
device of any suitable form.
(2) The combination of the above jaws, ring and controlling device with a stop
or series of stops for the purpose of releasing the grip of the jaws upon the carbon
or carbon carrier substantially as described.
(3) In the controlling mechanism of an arc lamp the combination of a solenoid
with movable iron core suitably attached to the ends of the griping and releasing
device mentioned in Claim 1 and substantially as described.
(4) The use of a heat retaining substance for the cap to cover the inner globes
of arc lamps of the enclosed type, for the purpose herein set forth, and substan-
tially as described.
(5) The combination of the parts figured and mentioned herein and in the
above claims for the purpose set forth and described.
1000