Improvements in Enclosed Electric Arc Lamps.
Year: 1899

page_text: Date of Application, 22nd Nov., 1899 -Accepted, 30th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in Enclosed 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
our said invention (which has been communicated to us from abroad by
Ozro Newcome Wiswell, of Lynn, in the County of Essex, State of Massa-
chusetts, United States of America, Electrical Engineer); and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
With electric are lamps having a small enclosing chamber around the arc it
is customary to provide a cover for the enclosure which is designed to exclude
as much oxygen from the are as possible; this is done in order to prolong the
life of the carbons.
In the practical construction of are lamps of the enclosed type, it has been
impracticable to make a fit between the carbon and the cap, and between the
cap and the enclosure which is good enough to exclude all of the oxygen from
the enclosure after the lamp has started into operation, although such results
are obtained as will greatly increase the carbon life. This failure is partly due
to inaccuracies in the carbons, and partly to inaccuracies in the cap and enclo-
sure. In the ordinary burning of the lamp the upper carbon pumps up and
down more or less, and by its action either expels a certain amount of inert gas
from the enclosure or sucks into the enclosure a certain amount of oxygen. So
long as a body of carbon gas is constantly maintained in the enclosure, the carbon
life is greatly prolonged, but as soon as oxygen is admitted the carbon life corre-
spondingly decreases.
gas
We have discovered that if a suitable chamber is provided into which the inert
gas is forced, instead of into the surrounding atmosphere, that the carbon life
can be materially increased. By this construction, when the distance between
the carbons is decreased from any cause, the amount of inert gas which is dis-
placed by the moving carbon or carbons, is forced into the chamber, and remains
until the carbons are again separated when it is returned to the enclosure, due
to the pumping action of the moving carbon or carbons.. Of course some
may escape during the time that this action takes place, but the main body
of gas acts in the manner described. The chamber may be of any desired
character, either straight or irregular, but preferably it should be of greater
capacity than would suffice to contain the displaced gas or combination of gases.
When the chamber is of the proper size no appreciable amount of oxygen will
be admitted to the enclosure, even though the carbons move over their entire
range; in other words, a chamber of varying capacity is provided into which the
gas enters or is withdrawn, the extent of movement of the carbon in no way
affecting the principle of operation.
We do not wish to be understood as limiting ourselves to the use of a chamber
the capacity of which is greater than that necessary to receive the gas displaced

page_text: by the moving carbon or carbons, since excellent results can be obtained if the
chamber is more limited in capacity.
In the accompanying drawings which show an embodiment of our invention,
Fig. 1 is a cross section of a simple form of gas cap resting upon an are enclosing
cylinder; Fig. 2 is a side elevation of a gas cap, Fig. 3 is a plan view of the gas
cap with the cover removed, Fig. 4 is a sectional view of the same, taken on
line 3-3 of Fig. 3, Fig. 5, shows a modified form of gas cap and Fig. 6 is a cross
section of the same.
Referring to Fig. 1, A represents an arc enclosing cylinder of any desired con-
struction, and mounted in the top thereof is a gas cap B. The cap is provided
with a central opening to permit the passage of the upper carbon C. The
carbon and opening are so arranged that the carbon may move freely in a
vertical direction. Surrounding the central opening and concentric therewith
are chambers D and D¹ in which whirls of gas or air are created when the
carbon C moves up and down and prevent the free exchange of gas and air in
the enclosure. Surrounding the outside of the cap is a deep groove E, forming
a chamber which acts to prevent the free exit of gas from the cylinder or the
entrance of oxygen.
Mounted in the cap, and communicating with the chamber D₁ is a tube F,
into which the inert gas from the enclosure passes when the carbons are made
to approach, and from which a supply of inert gas is received when the carbons
separate. For convenience we have shown the tube bent downward like an
inverted U, but any other form may be adopted if desired. Assuming that the
carbons C and C are half-inch carbons and that the normal separation is from a
half to five-eights of an inch, then the capacity of the auxiliary gas chamber or
tube F should be great enough to receive all of the gas forced out of the
enclosure A, with something to spare when the carbons come together. For
example the dotted line f indicates roughly the point to which the inert gas
would be forced if the carbons C and C₁ were made to strike.
The auxiliary chamber should be so arranged that it offers very little resistance
to the passage of the gas from the enclosure; in the present instance the tube F
communicates with the concentric chamber D¹ but it could be connected with
the chamber D only it would offer slightly more resistance to the passage of the
gas. Or a single chamber could be substituted for those shown, and the tube
connected therewith, or the tube could enter the enclosure directly. Instead of
utilizing a tube, as shown, when the cap is held stationary and the enclosure A
forced up against it, the side tubes which support the yoke and lower carbon
holder may be employed, and a suitable connection provided between the
enclosure and the side tube or tubes.
Regarding the action of this auxiliary chamber, the chambers D and D¹, and
the chamber formed by the groove E must not be considered as a part thereof,
for they act to check the passage of gas and air, whereas the auxiliary chamber
aims to present a comparatively free receptacle for the gas. In the same way
the inert gas is prevented from escaping when the carbons approach, so the air
is prevented from entering the enclosure when the carbons separate, for the
action of the carbons separating will suck or pump back the gas previously
expelled into the auxiliary chamber.
Referring to Figs. 2, 3, and 4, we have shown a slight modification of the cap
in which the auxiliary chamber F is made in the form of a spiral and lies in a
horizontal plane; this arrangement is better than the one previously described
since the gas has no tendency to move when the gas in one portion of the chamber
is slightly heavier than that in another portion.
As before the cap is provided with a central carbon opening, and two con-
centric chambers D and D¹ surrounding the opening to check the free entrance
of air and the exit of gas around the carbon. In addition to these chambers
is a third and large chamber D2 located at the bottom where the gas can enter
with comparative freedom. This chamber communicates by a vertical hole D³

page_text: with its spiral auxiliary chamber F. The chamber is formed by a spiral groove
on the top of the cap and a cover H which fits over the groove and is secured in
place by screws. The action of this cap is the same as the one shown in Fig. 1,
except that the gases have no self moving tendency due to differences in weight.
This cap is more desirable from a commercial point of view since it occupies
less space, and where the tendency is toward short lamps, as it is at the present
day, this is an important item.
In Figs. 5 and 6 we have shown a slight modification of the cap previously
described: the essential difference lies in the fact that the auxiliary chamber F
is not made in the form of a spiral, but consists of two communicating
chambers F and F. The chambers, as shown, are concentric and are formed by
grooving the top of the cap and securing a cover to the cap by screws.
For
convenience we have spoken of the chambers F and F¹, but these constitute in
effect a single chamber, the object in placing the opening F2 opposite the open-
ing F3, which communicates with the atmosphere, is to provide a longer patlı
for the gas. There is a slight difference, however, in the construction of the
auxiliary chamber from those previously described. In all the previous
instances the gas and air have had but a single path to follow whereas they now
have two paths in multiple with each other as is clearly shown by the arrows.
In placing this attachment on electric arc lamps it is unnecessary to make
special provisions for rendering the enclosure air-tight, so long as the resistance
of the auxiliary chamber to the passage of gas is low the gas will enter into the
chamber in preference to taking the high resistance leaks.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same is
to be performed, we declare that what we claim is:-
-
1. The method of operating an arc lamp, which consists in confining the arc
within an enclosure from which all or practically all of the air is excluded,
and connecting said enclosure with a gas chamber into which the inert gas from
the enclosure can enter and withdraw, whereby the entrance of air is prevented
and the carbon life prolonged.
2. The method of operating an are lamp, which consists in confining the arc
within an enclosure from which the air is practically excluded and connecting
said enclosure with a chamber having an external opening into which the inert
gas from the enclosure due to the burning of the arc can freely enter and with-
draw, whereby the entrance of air is prevented when the carbons feed.
3. In a gas cap for an enclosed arc lamp, the combination of means for pre-
venting the free entrance of air into the enclosure, and the exit of gas, with
means for receiving the gas from the enclosure when the carbon pumps or
feeds.
4. In a gas cap for an enclosed arc lamp, the combination of means for pre-
venting the free entrance of air into the enclosure and the exit of gas, with a
chamber communicating with the enclosure into which the gas from the
enclosure freely enters and withdraws when the carbons change their position
with respect to each other.
5. A gas cap for enclosed arc lamps, comprising a cover having a gas chamber
into which the gas from the enclosure freely enters and withdraws, as the con-
dition of the amount of gas within the enclosure changes.
6. A gas cap for an enclosed are lamp comprising a cover for closing the open-
ing of a globe and a gas chamber communicating with the globe at one point
and with the atmosphere at another, the arrangement being such that the gas
from the globe is free to enter the chamber and to withdraw without permitting
the entrance of oxygen when the carbon electrodes move.
7. In a cap for enclosed arc lamps the combination of a plate having a carbon
opening and arranged to engage with an end of the globe, and a chamber com-
municating with the carbon opening at one point and with the atmosphere at

page_text: another into which the 'gas from the enclosure is free to enter and withdraw as the
carbons move with respect to each other.
+1}
. S. In a gas cap; the combination of a plate having a carbon opening and
arranged to cover one end of an arc enclosing globe, a groove formed in the top
of the plate, and a cover whereby the groove is formed into a chamber:
19. In a gas cap, the combination of a plate having a carbon opening and
arranged to cover one end of an arc enclosing globe, a groove 'formed in the top
of the plate, and communicating with the carbon opening at one end and with the
atmosphere at the other, and a cover for the groove.
10. In a gas cap for enclosed arc lamps, the combination of a plate having a
carbon opening, a divided chamber formed in the cap communicating with the
carbon opening, at one point and with the atmosphere at another.
11. In an electric arc lamp the combination of an enclosure for the arc, a gas
cap therefor, and a chamber connected with the enclosure which offers less
resistance to the passage of gas than do the openings through which the leaks
take place.
...
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21
1
12. A gas cap for an enclosed are lamp comprising a body of metal having a
central opening for the carbon, means for restricting the exit of gas from an
enclosure, and a long contracted chamber for receiving gas when a carbon
pumps.
ו' רד
3 13
1000
THE BRITISH THOMSON-HOUSTON Co. LTD.,
ALFRED CLEMENTS,
Assistant Secretary,
W. MARTINDALE,
A. R. MONKS,
}
Directors.