Improvements in Electric Arc Lamps.
Year: 1897

page_text: Date of Application, 14th Dec., 1897-Accepted, 22nd Jan., 1898
COMPLETE SPECIFICATION.
Improvements in Electric Arc Lamps.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of
this invention (which has been communicated to us from abroad by Elihu
Thomson, and Charles E. Harthan, residing respectively at Swampscott and
Lynn, both in the County of Essex, State of Massachusetts, United States of
America), 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 arc lamps, and has especial reference to that class
of lamps in which the arc is enclosed, and especially adapted to run on constant
potential circuits, with a resistance in the branch containing the lamp.
The invention embraces a number of improvements in the details of the con-
struction of such lamps, adapting them to be run with small currents, and
providing an efficient and economical arc lamp constructed and arranged as
hereinafter set forth and claimed.
Referring to the accompanying drawings, Fig. 1 is an elevation, partly in
section, of an arc lamp embodying detailed improvements in accordance with this
invention. Fig. 2 is an enlarged detail view in vertical section of a modification
of the dash pot connected to the upper carbon support. Fig. 3 is a plan of a
portion of the device shown in Fig. 2. Fig. 4 is a detail view in elevation, show-
ing the clutch mechanism. Figs. 5, 6, and 7 are detail plan views of the holding
device for the inner globe. Figs. S, 9, 10, 11, and 12 are details hereinafter
referred to. Figs. 13 and 14 are views in elevation of part of the supporting
frame for the carbons, showing the arrangement of the outer globe and its
support. Fig. 15 is an elevation partly in section and Fig. 16 is an elevation
showing the contact-making weight or follower for the upper carbon, and
Fig. 17 is an enlarged detail of the flange socket at the base of the lamp.
Referring to Fig. 1, the lamp is shown provided with the inner tube 1, in
which is located the tube 2 within which is the upper carbon 3 of the lamp,
arranged to slide therein, the upper end of said tube 2 being hinged to a
piston 4 arranged to slide in the dash pot 5, secured to the upper end of the tube 1.
A weight 6, located in the tube 2, bears on the upper end of the carbon 3, and is
for the purpose of producing a more positive action of the feed when the carbon
is released. A magnet coil 7 of insulated wire, preferably wound so as to resist
high temperature, surrounds the tube 8, within which is located a cylindrical
core 9, adapted to play up and down in accordance with the attraction exerted by
the magnet coil 7. The upper end of the cylindrical core 9 is tapered or
contracted as shown, to bear against the tube 2. The core 9 is partly a solenoid
core, and partly an electro-magnet core. The coil is preferably enclosed by an
iron-casing 10 extending over the ends thereof, thereby completing the magnetic
.

page_text: circuit around it and adding to the force exerted on the core 9. The core 9 is
secured at its lower end to the tube 2. The tube 1 is secured at its upper end to
the upper part of the lamp where the lamp is suspended, and the lower end of
tube 1 is secured to the upper part of the casing 10. A clutch mechanism is
provided to engage the upper carbon and to move with tube 2 and core 9, as
follows: 11 11 are the jaws for clamping the upper carbon, which are pivoted to
bell crank levers 12, pivoted in turn to a cross piece 13, which slides on guide
rods 14 depending from a cross piece 15 mounted on a portion 16
depending from the bottom of casing 10. The upper portion of levers 12
are bent in a horizontal direction to clear the tube 2, as shown in Fig. 6, and have
their upper ends pivoted respectively to the depending arms 17 of a yoke 18,
clamped to the tube 2. The tube 2, being lifted by raising of core 9, will cause
the levers 12 to be operated, thereby causing the lower or short arms of levers 12
to move upwards and inwards, and the jaws 11 11 to be moved upwards and
towards each other. This will cause the upper carbon to be firmly clamped and
the cross piece 13 will be slightly raised on the guide rods 14, simultaneously
with the upward movement of the tube 2. By this means the upper carbon is
separated from the lower, and the arc is formed in the inner globe 18. When
the current in the coil 7 is weakened, so as to let down the core 9, tube 2 goes
down with the yoke 18, the cross piece 13 also descends and when it reaches the s
lower ends of the guide rods 14 and rests on the nuts 14¹ at the ends of the latter,
the levers 12 will be relaxed, and the clamping jaws 11 11 set free from the upper
carbon 3. The carbon 3 is then fed downwards by gravity and the weight G,
until the feed is checked by the resumption of the power of the coil 7, owing to
the current having increased subsequently to the feed, the clutch being brought
into action and the jaws 11 11 again clamping the carbon 3.
In the construction of the support for the inner globe and lower carbon and the
outer globe, there are two vertical tubular guide rods 19 suspended at their
upper ends from a flange 20 of the casing 10, and extending through a plate 21,
which is the main portion of the bottom of a casing 22 enclosing the upper portion
of rods 19, casing 10, and magnet coil 7. In its lowered position the core 9
rests on the bottom of casing 22, as shown in Fig. 1. The guide rods 19 are
connected adjacent to their lower end. by a yoke 23 having a central circular
opening through which extends a short tube 24 having a flange 25 located above
the yoke 23. A ring nut 26 screws on to the lower threaded end of the tube 24, 3
and serves to clamp the latter to the yoke 23, proper insulation 27 being employed
as shown in dark lines in Figs. 1 and S.
The yoke 23 is provided with internally screw-threaded depending lugs 231,
to which are secured by screws 28 the cross piece 29, having a central depending
portion 30, with a transverse pin 31, adapted to be received, with portion 30, 4
into a slotted socket 32 in the yoke 33 see Fig. 17, carrying at its ends the
vertical rods 34, which slide in the tubular guide rods 19, and have at their upper
ends heads 35, which serve to prevent the rods 34 from sliding out of the rods 19,
by abutting in their downward movement against the headed screw threaded
thimbles or sleeves 36 in the lower ends of rods 19. The upper end of tube 24 4
tapers inwardly, and within the tube 24 is located a tube 36, split at its upper
end and having at its lower end a depending lug or projection 24¹ upon which
turns a cap 37 screwing on to the lower end of tube 24. The lower carbon 38
is mounted in the split tube 36, and when the latter is pushed up into the tube 24,
and the cap 37 is screwed up into place, the upper end of tube 36 is contracted 5
and clamps the carbon 38, so as to effectually centre and secure it in place. A
cylindrical shell or casing 39, contracted at its top so as to form an opening just
sufficient to allow the flange of the inner globe 40 to enter, screws on to the
flange 25 of tube 24.
A ring 41 is located in the space between the casing 39 and the tube 24, and 5
is free to move vertically therein. The ring 41 is provided with pins 42 pro-
jecting from its periphery through vertical slots 43 in the casing 39, and having

page_text: their ends located in a circumferential groove 44 in the inner surface of a ring
nut 45 which screws on the shell 39.
The upper surface of the ring 41 inclines upwards, and resting thereon are a
set of wire coils 46, such as shown in Figs. 10 and 11, arranged in a circle, and
having their depending ends 46 extending through vertical slots 41 in the
ring 41, as shown in Figs. 9 and 12, and engaging the flange 25 of tube 24,
thereby holding them in place, and preventing their movement in a circle, but
permitting their movement radially.
It will readily be seen that by means of the foregoing construction, upon the
ring nut 45 being screwed up, the ring 41 will be carried upwards, and the wire
coils adjustably clamped between the top of casing 39, ring 41, and the neck of
globe 40, thereby securing the neck of the latter in place, as shown in Figs, 1, 8
and 12. A cap 46 rests on the top of globe 40, through which the carbon feeds.
47 is the outer or main globe, having its neck resting in the flanged socket 48,
provided with set screws 49 for securing the globe to the socket as shown in
Fig. 17. The socket 48 is secured to the depending portion 30 of cross piece 29
by a bayonet joint, one of the slots 50 of the bayonet joint being shown which
engage and form with the transverse pin 31 the bayonet joint operated by turning
the socket 48.
The globe 47 is provided at its top with a cap 471 which when the globe is
raised to its closed position, compresses the spring 47" thereby aiding in holding
the globe steadily in position. The raising and lowering of the globe 47 and the
rods 34 in the rods 19 will be readily understood without further description.
The weight 6 is preferably made of a particular construction, as shown in
Figs. 15 and 16. The weight 6 is formed with a socket 51 at its lower end,
which may be provided with slots 52, as shown, to receive and engage the upper
end of the carbon 3, the socket 51 being secured to the weight by a screw 53,
or otherwise. The weight is provided with vertical grooves 54 terminating in a
socket 55 at the upper end of the weight, and in the vertical grooves 54 are
located delicate spring contacts 56, having their upper ends projecting into the
socket 55, and their lower ends bent and clamped between the socket 51 and the
weight, as shown. The spring contacts 56 are bent slightly outwards, so that
when the weight is located in the tube 2, the springs 56 will bear on the inner
surface of tube 2, and secure ample contact from the
passage of current.
In Figs. 2 and 3 is shown a modification of the dash-pot for the tube 2. In
this construction, there are two dash-pots 57, suspended from the ends of a yoke 58
clamped to the tube 2, and pistons 59, secured to the framework 60 below.
This modification is enclosed in a casing 61. The advantage of this construction
lies in the shortening of the lamp somewhat by a saving of the vertical space
taken up by the dash-pot, shown in Fig. 1.
In the construction of this lamp, a particular arrangement of and provision
for ventilating the resistance coils is provided as follows: The outer casing 62
of the lamp is preferably formed with a hood 63 about opposite the lower end of
coil 7, and below the hood 63 is an additional casing 64 enclosing a set of
resistance coils 65 encircling the portion of the lamp between coil 7 and top.
of globe 47. This resistance is supported in any way desired, out of contact
with the casing and is included in a branch with the lamp, when in use, by
suitable connections which are not shown.
The resistance in the present example is composed of spirals of German silver
wire led around the lamp and mounted on porcelain or other heat-resisting
insulators, in the usual way common to such structures, and connected in series
with the coil 7 and the carbons. Sufficient space is allowed around the resist-
ances for their thorough ventilation, and openings 66 are provided, just above
the cap 47 for the ingress of cold air, and beneath hood 63 for the egress of the
heated air which passes through the coils of the resistance.
In the entire construction of the lamp it is understood that insulation is used,

page_text: as indicated in dark lines, wherever it is needed to prevent the current from
taking any other path than that desired.
It may sometimes happen that the carbon 3 will break short off in the tube 2.
In such event it would be necessary to remove a portion of the lamp mechanism
in order to remove the broken end. To avoid the necessity of doing this, a
window or opening 18 is provided in the tube 2, above the yoke 18, as shown in
Fig. 4, by means of which the broken end of the carbon can be pushed out of
tube 2, by inserting a piece of metal through the opening 181.
Having now particularly described and ascertained the nature of the said inven-
tion (as communicated to us from abroad) and in what manner the same is to be
performed, we declare that what we claim is :-
:
1. In an electric arc lamp, a central carbon-carrying device, a yoke secured
thereto, dash-pots suspended from said yoke parallel with the carbon-carrying
device, and pistons engaging said dash-pots, as set forth.
2. In an electric arc lamp, the combination with a tube for receiving and
permitting vertical play therein of the upper carbon, of a clutch consisting of a
yoke secured to said tube, vertical guide rods, a cross piece mounted to slide on
said guide rods, bell-crank levers pivoted to said cross piece and pivoted at their
upper end to said yoke, and bent so that one bell-crank lever passes on one side of
said tube and the other bell-crank lever passes on the other side of said tube,
and clamping jaws pivoted to the lower ends of said bell-crank levers and adapted
to clamp the carbon, as set forth.
3. In an electric arc lamp, a solenoid located centrally in the lamp and having
a tubular solenoid core, a vertically movable tube extending through said sole-
noid core to which the latter is attached, a clutch mechanism connected to said
tube, a carbon vertically movable in said tube, a casing surrounding the magnet
coil, a second casing surrounding the magnet coil casing, and an air space between
said two casings, and vertical guide rods for the outer globe extending between
said casings, as set forth.
4. In an arc lamp, a central vertically movable tube for carrying the upper
carbon, a pair of dash-pots yoked to said tube, and pistons for said dash-pots
mounted on the main frame, as set forth.
5. In an are lamp, a centrally located enclosed solenoid, a resistance arranged
adjacent to and about said solenoid, an outer casing with an air space between
it and the solenoid casing and having a hood at its bottom, and a second outer
casing below the first outer casing and ventilated at its top and bottom.
6. In an electric are lamp, a clutch mechanism consisting of a fixed yoke,
vertical guide rods, a cross piece vertically movable on, said guide rods, bell-
crank levers pivoted to said cross piece and having horizontal "upper portions
pivoted to the yoke and bent on opposite sides to the carbon to clear the latter,
and rocking clutching jaws pivoted to the lower end of the bell-crank levers, as
set forth.
7. In an electric are lamp, a central vertically movable support for the upper
carbon, in combination with parallel dash-pots yoked to said carbon support, and
arranged on the sides of said support, as set forth.
8. In an electric arc lamp, a centrally located movable carbon-carrying tube,
a yoke secured thereto, dash-pots suspended from said yoke parallel with the
carbon-carrying device, and pistons engaging said dash-pots in combination
with a solenoid located centrally in the lamp and having a tubular solenoid core
attached to the said vertically movable carbon-carrying tube which extends
through said solenoid core, a clutch mechanism connected to said tube, a carbon
vertically movable in said tube, a casing surrounding the magnet coil, a second
casing surrounding the magnet coil casing and forming an air space between said
'casings, and vertical guide rods for the outer globe extending between said
casings, as set forth.
9. In an electric arc lamp, a magnet coil, a tube extending centrally through

page_text: said coil, and suspended from its dash-pot, an upper carbon located in said tube,
and a tubular solenoid core surrounding said tube and secured thereto; in combina-
tion with a clutch mechanism consisting of a fixed yoke, vertical guide rods, a cross
piece vertically movable on said guide rods, bell-crank levers pivoted to said
cross piece and having horizontal upper portions pivoted to the yoke and bent
on opposite sides to the carbon to clear the latter, and rocking clutching jaws
pivoted to the ower end of the bell-crank levers, as set forth.
10. In an arc lamp, a centrally located movable tube for carrying the upper
carbon, having an opening in its side permitting of access to and removal of the
) carbon when broken, as set forth.
Dated the 14th day of December 1897.
For the Applicants,
J. C. CHAPMAN,
Chartered Patent Agent, 70, Chancery Lane, London, W.C.