Improvements in Enclosed Arc Lamps.
Year: 1898

page_text: Date of Application, 7th Nov., 1898-Accepted, 17th Dec., 1898
CUMI LEIE DIEUIFICATION.
Improvements in Enclosed Arc Lamps.
We, FRANK MICHAEL LEWIS, Electrical Engineer, and the MUTUAL ELECTRIC
TRUST LIMITED, both of 111, Glo'ster Road, Brighton, in the County of Sussex,
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 are lamps of the enclosed type by means of which
certain advantages are obtained and it consists of certain novel details of construction
and combinations of parts having the following for their objects :-(a), devices by
means of which the enclosing glass is gripped in such manner that considerable
deflection and shock may be borne without opening up any passage for the gases
from the interior or for the outer atmosphere to the interior of the glass, (b), a device
or arrangement by which the sufficiently free feeding of the carbon to the arc space
is permitted whilst at the same time passage of gas or air is limited or checked,
and (c), a device for striking the arc.
In order that the invention may be clearly understood I have appended
drawings hereto which illustrate how the invention is to be or may be carried into
effect.
In the figures similar numerals of reference indicate similar parts.
In the said drawings,
Figure I is a vertical central section of the lamp.
Figure II is a plan of the parts shown in Figure I.
Figure III is a section on the line III-III of Figure II.
Figure IV is a plan view of the are striking device, and
Figure V a sectional elevation of the same on the line V-V of Figure IV, the
carbon in this case being shown in elevation.
In the said figures, 1 is the glass within which the arc is enclosed and 2 is the top
plate thereof. This top plate is kept pressed against the glass by means of two
pointed metal rods 3, 3 sliding in tubes 4, 4 attached to the main cross-piece 6.
5, 5 are counter springs in the tubes 4, 4, which tubes are closed at their upper
ends, the said springs 5, 5 serving to press the rods 3, 3 downwards. The points of
the said rods enter the cup-shaped recesses 15, 15 so as to prevent undue lateral
movement of the top plate 2. 16, 16 are headed pins whose lower ends are firmly
screwed into the top plate 2. These pins project upwards through the wide
orifices 17, 17 (see Figure III) and end in enlarged heads 13 as shown. The
said headed pins serve to prevent the top plate dropping away when the glass is
removed.
The lower end of the glass is closed by the bottom plate 7 which fits over the top
of the lower carbon holder 8 and rests on the shoulder 18 thereof. The said lower
carbon holder is closed at the bottom and has a globular part 19 thereon forming
a kind of ball and socket joint with the tightening plate 9, which latter screws on to
the tubular portion 20 of the lower cross-piece 10. The main cross-piece
and the
ower cross-piece 10 extend between the frame rods 11, 11 and may be attached
hereto in any well known manner.

page_text: It will be seen that the glass 1 may be tilted through a considerable angle in any
direction without any separation between it and its top and bottom plates being
effected. For it will be observed that the top plate will yield by compression of the
springs 5 so as to admit of canting in any direction and similarly the ball and socket
joint at the bottom of the glass will enable the bottom plate 7 to be similarly canted.
The result is that under the action of the springs 5 the glass 1 is securely clamped
between plates and 7 so that it may be tilted through a considerable angle and
sustain considerable shock without any opening of the joint between the glass and
the said plates admitting of passage of air to or from the interior of the glass taking
place. It will be understood that the flanges of plates 2 and 7 and the edges of the
glass which press upon said flanges are machined or ground true so as to secure an
air-tight fit.
'
It will be seen that the lower carbon holders being closed at the bottom, and
bottom plate 7 and tightening plate 9 fitting accurately on the said carbon holder,
there will be no access of air at the lower carbon. The upper carbon is fed through
the orifice 12 in the top plate 2. Instead of leaving this orifice with a cylindrical
wall so as to tightly embrace the carbon I cut a female thread in the wall in such
a manner that the thread is a taper one, that is to say the depth of the thread in-
creases upwards or downwards as the case may be preferably however it is cut so
that the said thread is deepest at the bottom of the orifice and shallowest near
the top of the said orifice. I find that this makes a good passage way for
the carbon and at the same time sufficiently restricts passage of the air or
gases.
In Figures IV and V, I illustrate the device for striking the arc. This device
consists of a forked piece 21 between the limbs 24, 24 of which are the clutch seg-
ments 22, 22 which grip the upper carbon as will be hereinafter described. These
clutch segments are loosely mounted upon the guide bars 23, 23 which pass through
the limbs 24, 24 of the forked piece. It will be seen (see Figure IV) from the rela-
tive positions of the said guide bars and of the tubes 4, 4 that the parts are retained
in proper position. At the outer or junction end of the forked piece is a split lug 25
which may be attached by a link or otherwise to the solenoid core or equivalent part
of the lamp mechanism and it will be seen that when this part is raised the clutch
is canted and the segments 22, 22 grip the carbon, raise it, and cause the arc to be
struck. When the forked piece is lowered and returns towards its horizontal position
the grip of the clutch segments is released and the carbon allowed to feed. In
practice I prefer to cut a thread 26 or series of annular grooves on the arc-shaped
surfaces of the segments which embrace the carbon. By this means a more reliable
grip is obtained.
It will be seen that the two segments 22, 22 fulfil the same functions as an
ordinary ring or washer clutch as used in many are lamps, in fact they constitute
a divided washer and act more reliably than an ordinary undivided washer clutch
would do.
In practice I sometimes find it convenient to rigidly attach the bottom plate 7 by
screwing or otherwise to the lower end of the glass by means of a separate metal
sleeve or socket attached to the said glass.
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 arrangement and combination of parts by means of which the glass may
be deflected without any opening of the joint substantially as set forth.
2. The combination of enclosing glass, top plate, and means for pressing said top
plate downwards and allowing of its being moved or canted in any direction substan-
tially as set forth.
3. The combination of lower carbon holder, bottom plate 7, and tightening plate 9
substantially as and for the purpose set forth.

page_text: 4. The threaded passage way 12 substantially as and for the purpose set forth.
5. The arrangement and combination of parts for striking the arc substantially as
set forth.
Dated this 5th day of November 1898.
For the Applicants,
J. G. LORRAIN, M.I.E.E., M.I.Mech. E.,
Norfolk House, Victoria Embankment, London, W.C.,
Chartered Patent Agent.