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Патент USA US2125171

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July 26, 11938.
J. F. PETERS
2,125,171
BRUSH FOR HIGH INTENSITY ARC SEARCHLIGHTS
Filed Feb. 27, 1937
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WITNESSES:
INVENTOR
John F Defers.
Patented July 26, 1938
2,125,171
UNITED STATES PATENT OFFICE
2,125,171
BRUSH FOR HIGH INTENSITY ARC SEARCH
LIGHTS
John F. Peters, Edgewood, Pa., assignor to West
inghouse Electric & Manufacturing Company,
East Pittsburgh, Pa., a corporation of Pennsyl
vama
Application February 2'7, 1937, Serial No. 128,202
13 Claims. (Cl. 176—119)
My invention relates to are searchlights and
of the brush contact surface. This repeated
more particularly to the brushes used to conduct reaming shortens the brush life and causes ex
current to the electrodes of such searchlights.
cessive replacement and maintenance costs.
In the operation of arc searchlights, it is com
The object of my invention is to provide a
5 mon practice to feed the electrodes to the are as
they are consumed in the are by moving the
electrodes, which are usually round rods, toward
the arc in the direction of their axes.
In addi
tion to the longitudinal motion, the electrodes,
10 and particularly the positive electrode, are ro
tated about their axes to secure even consump
tion of the electrode in the arc. Because of the
relative motion of the electrode and the electrode
holder, or electrode head as it is sometimes called,
1,; it is necessary that contact brushes be mounted
on the head to bear upon the electrode to conduct
current thereto while the arc is burning.
High intensity searchlights such as operate on
ciu'rents of from 150 to 250 amperes require that
Lt‘. very good contact be maintained between the
brush and the electrode to prevent excessive
arcing and resultant burning of the brush. Poor
contact between the brush and the electrode
causes considerable power loss and voltage drop
between the brush and electrode. Such power
loss causes heating of the brush which in turn
causes pitting and deterioration of the brush.
Such pitting further increases the contact re
sistance between brush and electrode and so the
condition is aggravated until it is necessary to
replace the brush or re?nish its contact surface.
Pitting of the brush surface also'increases the
sliding frictional resistance between the brush
and the electrode thus placing an excessive bur
den upon the electrode feeding mechanism.
The contact surface of the brushes in common
use heretofore has been in the form of a cylin
drical surface intended to cover the electrode
surface. It has been found that the diameters of
40 the electrodes vary both as between electrodes
and in the individual electrodes. It is apparent
that, in order to permit the brush contact sur
face to cooperate with all electrode diameters,
it is necessary that the diameter of the brush con
AS tact surface be made at least as large as the
" largest electrode diameter that is likely to be
encountered.
As a result of the construction just described,
single line contact exists between the brush and
Cir C. the electrode except when the maximum diam
eter of electrode is engaged by the brush. This
means that only line contact exists between the
brush and the electrode.
(A 5
As a result a high con
tact resistance exists, causing the brush to pit
excessively and necessitating frequent reaming
brush for use with the electrodes of an arc search
light which shall have a lower contact resistance
than brushes now employed.
Another object of my invention is to provide
Cl
a brush for use with the electrode of an arc
searchlight which shall have its contact surface 10
so shaped as to provide a plurality of line contacts
between the brush and the electrode.
A further object of my invention is to provide
a brush for use with the electrodes of an arc
searchlight which shall have its contact surface
so shaped as to minimize the contact resistance
between the brush and the electrode.
A still further object of my invention is to pro
vide a brush for use with the electrode of an arc
searchlight which shall have its contact surface 20
so shaped as to minimize the heat generated and
consequent pitting at the brush contact surface.
Another object of my invention is to provide a
brush for use with the electrode of an are search—
light which shall have its contact surface so 25
shaped as to prolong the life of the brush thus
obtaining increased maintenance and replace
ment economies.
Another object of my invention is to provide a
brush for use with the electrode of an are search.
light which shall have its contact surface so
formed as to provide two line contacts between
the brush and the electrode thus insuring that the
electrode be held securely against lateral move
ment.
Another object of my invention is to so shape
the contacting surface of a brush for the elec
trode as to obtain a high contact pressure per
unit of contact surface and to thus provide a
better conducting contact between the brush and
41)
electrode.
These and other objects of my invention will be
apparent after reading the following detailed
description in connection with the accompany
ing drawing, in which
Figure 1 is a diagrammatic illustration of the 45
electrodes and electrode feeding mechanisms of
an arc lamp with the brushes in their coopera
tive relationships.
Fig. 2 is an end elevational view showing the
contact relation between an electrode and a
brush which has a cylindrical contact surface.
Fig. 3 is an end elevational view showing the
contact relation between an electrode and a brush
embodying the principles of my invention.
55
2
,
2,125,171
Fig. 4 is a perspective View of the brush shown
in Fig. 3; and,
Figs. 5 and 6 illustrate the contact relation
the electrode to be used with the brush and such
between an electrode and modi?ed forms of
brushes embodying my invention.
the brush contact pressure above or below that
obtained by the plane surfaces of the V-shaped
slot shown in Fig. 3, the V-shaped slot may have
In carrying out my invention, I have provided
on the arc head unit of a'searchlight, a pair of
brushes with V-shaped slots in that end of the
brushes which bears on the electrode, with the
10 slots running longitudinally of the electrode and
each side of the slot contacting the electrode.
Referring to Fig. 1, I have illustrated the posi
tive and negative electrodes i and 2 of an arc
Searchlight with the mechanism for feeding the
15 electrodes to the are 3 and 4, and the mechanism
5 for rotating the positive electrode, these feeding
and rotating mechanisms being driven by a con
stantly rotating motor 6 through suitable gearing‘.
Power for energizing the arc is supplied to the
electrodes through brushes 1 and these brushes
are energized from a suitable power source, as
illustrated.
It is understood that this mechanism is only
illustrative and the gearing mechanisms are not
25 drawn to scale. The mechanism for rotating the
positive electrode is provided to insure even burn
ing of the positive electrode. The mechanism for
feeding the electrodes to the are are provided to
compensate for the consumption of electrodes in
30 the arc and to maintain the arcing tips in a
?xed position.
It will be seen that the positive electrode has
both a rotational and a sliding movement relative
to its brushes. In Fig. 2, I have shown the usual
Heretofore, this
has been a cylindrical surface and because of the
variation in the diameter of the electrode along
its length and the variation in diameter as be
tween electrodes it is apparent that a brush sur
35 form of brush contact surface.
' face diameter could not be chosen that would ?t
all electrodes, that the surface diameter would
have to be at least as large as the largest ex
pected electrode diameter, that electrode diam
eter in most cases would be smaller than the
4.5 brush surface diameter and that contact between
the brush and the electrode would be only line
contact at the point A.
Furthermore, the cylindrical contact surface of
the brush might vary from line contact to surface
50 contact depending on the relative diameters of
the brush surface and the electrode. This gives
a variation in contact pressure between the brush
and the electrode and as this contact more nearly
approaches the surface contact, there is not suffi
55 cient unit pressure between these surfaces to in
sure good conduction between the brush and the
electrode.
For these reasons, it was necessary that as near
as possible to line contact be maintained between
60 the brush and the electrode at all times. This
line contact is obtained by providing the brush
shown in Fig. 3. This brush has a V-shaped slot
lengthwise of the brush and the electrode ?ts into
this slot, as illustrated. Such an arrangement
65 provides line contact between the brush and elec
trode at the two points B, thus insuring high unit
pressure between the brush and electrode and
providing two of these high pressure contact sur
faces.
The angle between the sides of this V-shaped
70
slot shown in Fig. 3 may be taken as merely illus
trative of the principle of this invention and is
not necessarily the exact angle which will give
The angle for obtaining the best
results would probably vary with the diameter of
_ the best results.
angle would have to be determined by experiment.
If it should be desirable to increase orrdecrease
side surfaces which are convex or concave as il
lustrated in Figs. 5 and 6. It will be noted that
the same principles apply in these modi?cations,
that line contact is obtained between the brush
and electrode at two separated positions on the
electrode and that the contact of the two sides of
the V-shaped slot with the electrode serves to
maintain the electrode at a ?xed position and
15
prevent lateral movement of the electrode.
Experimentation and use in practice have
shown that the shaping of the brush contact sur
face after the manner illustrated and described
has prolonged the life of the brushes and has
made it necessary to re?nish the contact surfaces
of the brushes less often than when the cylindri
cal contact surface illustrated in Fig. 2 is used.
It has also been found that the centering effect
of the V-shaped contact surface on the electrode
has resulted in a better beam projected from the 25
Searchlight, since the variations in the beam in
tensity and focus have been eliminated by pre
venting lateral movement of the electrode.
In compliance with the requirements of the
patent statutes, I have shown and described here
in a preferred embodiment of my invention. It is
understood, however, that the invention is not
limited to the precise construction shown and
described, but is capable of modi?cation by one
skilled in the art, the embodiments herein shown
being merely illustrative of the principles of my
invention.
I claim as my invention:
1. In an arcing device in which the electrode
is rotated about its axis and is moved axially to 40
feed it to the are, means for conducting current
to the electrode comprising a ?xed brush having
a V-shaped slot, the sides of the slot serving as
the contact surfaces between the brush and the
electrode.
45
2. In a brush for conducting current to an elec
trode of an are, which electrode rotates and is
moved into the arc, said brush being so formed
as to maintain substantially line contact with the
electrode at a plurality of circumferentially spaced 50
positions on the electrode.
3. In an arc Searchlight having means for
rotating an electrode and feeding the electrode
to the are, a ?xed brush for conducting current
to the electrode, said brush being so formed as 55
to provide a plurality of surfaces in different
planes as surfaces of contact with the electrode.
4. In a means for maintaining electrical con
tact with a substantially cylindrical surface which
rotates about its axis and which moves in the 60
direction of its axis, a brush made of conducting
material and having a slot, in one side thereof,
said slot being so formed that, when the brush
is placed in contact with said cylindrical surface,
with the cylindrical surface lying in the slot, each 65
of the slot surfaces will maintain substantially
line contact with the cylindrical surface.
5. In a device for maintaining electrical con
tact with a body having a substantially cylindrical
surface which has a motion in the direction of 70
its axis and rotation about its axis and Whose
dimensions may lack uniformity, a brush made
of conducting material and having a slot so
shaped that each of its surfaces, acts as a con
tact surface between the brush and said body.
2,125,171
6. In a device for maintaining electrical con
tact with a body having a substantially cylindrical
surface which has a rotational movement about
its axis and a movement in the direction of its
axis and whose dimensions may vary from point
to point along the length of the body, a brush
made of conducting material and having a V
shaped slot, the sides of the slot being curved and
serving as the contact surfaces between the brush
and the bodies.
'7. In a device for maintaining electrical con
tact with the electrodes of an electric arc, which
electrodes are rotated about their axes and moved
in the direction of their axes, are substantially
15 circular in cross section and may vary in dimen
sions, cross sectional shape and degree of
straightness both as between points along the
individual electrodes and as between electrodes,
a brush made of conducting material and having
20 a slot with curved sides, said slot being so dis
posed that its sides form contact surfaces be
tween the brush and the electrode.
8. In an arcing device having an electrode
which is rotated and fed to the are as it is con
25 sumed in the arc, a brush for conducting current
to said electrode, said brush having a surface
for contacting the electrode which comprises a
V-shaped slot having sides which are plane sur
faces.
30
9. In an arcing device having an electrode
which is rotated and fed to the arc, a brush for
3
conducting current to the said electrode, said
brush having a contact surface in the form of a
V-shaped slot whose sides are curved surfaces.
10. In an arcing device having an electrode
which is rotated and fed to the arc, a brush for
conducting current to the said electrode, said
brush having a contact surface in the form of a
V-shaped slot whose sides are convex.
11. In an arcing device having an electrode
which is rotated and fed to the arc, a brush for 10
conducting current to the said electrode, said
brush having a contact surface in the form of a
V-shaped slot whose sides are concave.
12. In an arcing device in which an electrode
of substantially circular cross-section is rotated 15
about its axis and is moved axially to feed it to
the arc, means for conducting current to the
moving electrode comprising a ?xed brush bear
ing against the electrode, said brush having a
V-shaped slot, the sides of said slot serving as
contact surfaces between said brush and the elec
trode.
13. In an arcing device having an electrode
which is rotated and fed to the arc, a brush for
conducting current to the electrode, said brush 25
having a contact surface in the form of a V
shaped slot whose sides are surfaces generated
by the movement of a substantially straight line
while maintaining the line parallel to a predeter
mined line.
30
JOHN F. PETERS.
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