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Патент USA US2403471

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July 9, 1945-
c. G. VAN BRUNT
C
2,403,471
ELECTRICAL CONTACT BRUSH
Filed June 21', 1941
[4460052.
(‘0,4 774/6‘ .
'
Inventor :
Charles G._\_/ah Brunt;
, _ by WWQJMAH.
‘His Attlorne‘gw
Patented July 9, 1946 -
2403;471
UNITED ' STATES PATENT.‘ OFFICE
Charles G. Van Brunt, Schenectady,
slg-nor
General]
tion ofto
New
Yor Electric Company, ‘a corpora
Application June 21, 1941, Serial No. 399,125
14 Claims. (o1..'171__325)
My invention relates to electrical contact ele
ments and particularly to improved contact‘
brushes and methods of makinglthe same.
An object of my invention is to ‘provide an im
proved electrical contact element.
Another object of my invention is to provide
an improved electrical contact element formed of
a porous block of electrically conductive material
provided with a lubricant for the contact surface
thereof.
moves on its
'
described.
A further object of my invention is to provide 10
an improved method of making an electricalcon- ‘
tact element.
,
g
In the drawing, I have shown an electrical
contact element includinga porous block III of
bonded ?nely divided electrically conductive ma
16
commutator ‘and slip-ring brushes. A terminal
the features of novelty which characterize my in
vention will be pointed out with particularity in
the claims annexed to and forming part of this
speci?cation.
20
'
The single ?gure in the drawing illustrates a
contact brush for a dynamo-electric machine em
bodying my invention and made in accordance
clip ii is secured to the porous block In ‘by a rivet
l2 and an electrically conductive pigtail member
i3 is secured to theterminal clip H and to a con
necting terminal element
7
It for conducting cur-
rent between a ‘brush holder connector and the
~ contact element block l9. ‘In order to provideva
lubricant to the contact surface 15 of the porous
'
with my improved method of, manufacture. '
block I0, a'portion of the block below the termi
It has been found that under normal atmos 26 nal clip ll ,3 or the entire porous’ block ill; is im- 7
pheric conditions with average humidity, atmos- - ' pregnated with a hygroscopic material, such as
a polyhydric alcohol solution. Among the poly
hydricralcoholswhich have been found to pro
It has also been found that
electrical contact elements made of porous blocks
of ?nely divided electrically conductive mate
rial, such as carbon or metal and graphite
vide an eilicient lubricant for the contact‘sur
3.9 face of the brush‘ Hi, the ethyleneglycols have
been found to be particularly‘ eillcient. Mix
I tures of ,di?‘erent polyhydric alcohols also have
good lubricating properties. ‘These impregnants
brushes, tend to wear away very rapidly in dry
atmospheres. In the past, different lubricants
*
are'highlyhygroscopic' and water soluble and
have a
wide liquid state temperature
range.‘ relatively
Generally, they_'also have‘ the desirable
' properties of a relatively high ?ash polntand
a relatively low vaporpressure at normal con
40
element, through vibration or otherwise, to form
I substances which impede the ‘free movement of
the contact element on its guide member or brush
holder, thereby decreasing the emciency of oper
ation of the combination. It has been found,
however, that by impregnating a, porous block of
electrically conductive material with a humec
tact element operating temperatures. For cer
tain types of electrically conductive materials,
such ' as carbon, electrographitic, or natural
graphite brushes, a-solution of from 10% to 30%
of nonaethyleneglycol,
1
‘
'
Hoe-In (entering) ajCI-IaOH
in water has been found to be a very e?lcient im
pregnant, especially if the metalcontent of the
brush is 50% or less. For contact elements
tant, such asa polyhydiic alcohol or an alcohol
wherein the porous material comprises a very
ether, or mixtures of these, in at least a portion
of the block, lubrication is provided for the con 50 large amount of metal,‘ 60%‘ or more, an. impreg
tact surface thereof which greatly increases the
life of the porous block. Furthermore; I have
found that under certain conditions and for cer
'nant comprising
40% to 60% nonaethyleneglycol
'
and 20% to ‘30% polvole?n glycol inwater is a
tain types of materials, the contact element is
In forming my improved contact elements, it
has been found desirable to desas the porous
very e?lcient lubricant.
'
‘
-
2,403,471
tion providing a lubricant for the contact surface
block by subjecting it to a relatively low pressure I
and then impregnating the degassed block with
the lubricant, after which excess impregnant is
of said element, and a coating on the sides of said
block, said coating being‘ impenetrable by said
impregnant.
' removed from the block, and, in certain cases, a
v2. An electrical contact element including a
porous block of ?nely divided material, at least
relatively thin coating of material, which does '
not react with the
impregnant and is otherwise '
a ‘portion of said block being impregnated with
an alcohol-ether solution providing a lubricant
for the contact surface of said element, and a.
thin coating on the sides of said block. said coat
stable under operating conditions, is applied to
the sides of the dried block. In degassingv the
porous block, the contact element is immersed in 10
the impregnant, such as a 20% to
ing being vimpenetrable by said impregnant.v
' a solution of
40% solution of nonaethylene glycol in water or
3. An electrical contact element including ‘a
benzene, and the block is subjected to a relatively
porous block of ?nely div'ded electrically conduc
tive material, at least a portion of said block being
low pressure in‘ this solution for one to two hours,‘
such that the water or benzene boils, removing
impregnated with a‘ polyhydric alcohol solution
the gas from the porous block. After thistreat 16 providing a lubricant for the contact surface of
’
said element, and a lacquer coating on the sides
'ment, a part
or the whole of the porous block is
impregnated at substantially atmospheric pres
of said block.
_
_ v4. An electrical contact element including'a
sure with a solution of- polyhydric alcohol in
porous block of ?nely divided material at least
Excess impregnant then is removed from the out 20 a portion of said block being impregnated with a
polyhydric alcohol solution providing a lubricant
side of the block in any suitable manner, as
by wiping or draining. The block maythen be ‘ . for the contact surface of said element, andv an
dried at a temperature ‘between 70° and 120° C. ' _ air drying lacquer coating on the sides of said
water or benzene for from one to two hours.
to remove excess water from the brush.
As
' stated above, with certain porous materials, it
is desirable to provide a very thin coating of non
26
vpaste . forming material .over the sides of the _
block.
.
5. An electrical contact element including a
porous block of ?nely divided material, at least
a portion of said block being impregnated with a
- polyhydric alcohol solution providing a lubricant
for the contact surface of said element, and a cel
block. I have found that a thin coating of cer
tain lacquers applied to the sides of the block
provides an e?lcient surface which will not react. 30 lulose acetate lacquer coating on the sides of said
with the impregnant or other adjacent materials,
block.
even after long. periods of use and vibration over ,
tively prevent the penetration or exudation of
impregnant through the coating.‘ This lacquer
'
'
_
'
g
H 6. An electrical contact element including a
a-supporting or guiding surface and will effec
porous block of ?nely divided material, at least
a portion of said block being impregnated with a
35
polyhydl‘ic alcohol solution providing‘a lubricant
preferably is of an air-drying type, such as ace
for the contact surface of said element,‘ and a
cellulose nitrate lacquer coating on the sides of
tone-‘soluble cellulose ‘nitrate or cellulose acetate,
which provides a ‘relatively low-friction guiding
said block.
I surface for the brush on' its brush holder and
_
v
‘ _.
,
7. The method of making an electrical contact
effectively prevents sticking of the brush in'the 40
element including forming a porous block, de- I '
holder.
gassing the porous block, impregnating .at least
I have found that a lacquer having a
a part of the degassed porous _ block‘ with
viscosity of three or four times that of water
provides a very satisfactory coating. Acetone
a poly-’
hydric alcohol solution, and applying to the sides '
‘soluble cellulose acetate dissolved in the solvent
of the impregnated block a relatively thin coat
45
in. proportions of about fivev grams of solid cel
ing of material impenetrable by the impregnant.
lulose acetate to 95 cc. of acetone gives ao’lacquer
8. The method of making an electrical contact
element including forming a porous block or elec
trically conductive material, degassing the po
rous block by subjecting it to a relatively low
of the above type.’ The desired impenetrable sur
face coating is formed on the sides of the block
III by dipping or immersing the block for fifteen
seconds to a minute in the lacquer, then draining
and wiping orshaking off excess lacquer. This
fills the pores on the sides of the‘ brush and
prevents exudation of the impregnant. Cellulose _
applied in thisv same manner also
pressure, impregnating at least a part of-the de- .
gassed porous block with nonaethylene glycol, re
moving, excess impregnant from the block, and
applying to the sides of the block a relatively thin
coating of material. impenetrable by the impres
‘has given very good results. Other lacquers also
to the block ‘
have proved successful when applied
The
chiefv
requisite '
in relatively thin coatings.
nant.
ofv the lacquer coating is that it must not react
with the impregnant and must prevent exudation ,
'
J sure, impregnating at least a part of the degassed
porous block with a polyhrdric alcohol solution.
removing excess impregnant from the block by
and applying a relatively
' draining and by drying,
thin coating of lacquer to the sides of the dried
limited'
to the‘ particular ar-'
_
block.
not depart from the spirit
_.
material, degassing the porous
block by subjecting it to a relatively low pres-.
rangements disclosed, and I intend in the ap
i?cations wh'ich'do
pended claims to cover all m'and
scope ofrmy in
~
~ _ trically conductive
of the impregnant from the surface of the brush.
While I have illustrated and described particu;
lar embodiments of my invention, modi?cations
thereof will occurto those skilled in the ‘art. I
desire to be understood, therefore, that my inven
tion' is not to be
.
9. The method of making an electrical contact
element including forming a porous block of elec
_
.
,
10. The method of making an electrical con
forming a porous block of
" tact element including
electrically conductive‘, material, degassing ‘the
What I claim as new and .desire- to secure by‘ 70 ‘porous block-by subjecting it to a relatively low
vention,
'
'
'
'
Letters Patent of the United States is: -
I. An electrical contact; element ‘including a
porous block of finelydlvided electrically conduc
pressure, impregnating at least a part of the
degassed porous block with .a solution of non‘,
aethylene glycol and polyoleiln glycol, removing
excess impregnant from the block, app1ying a rel
ing impregnated with a polyhydric' alcohol solu 76
tive material, at least a portion of said block be
2,403,471" v
5
.
atively thin coating of lacquer to the sides of the
dried block, and removing excess lacquer.
11.) The method 'of making an electrical con
tact element including forming a porous block of
electrically _ conductive material, degassing ‘the -
porous block by subjecting it to a relatively low
pregnant from the block by draining and by dry
pressure, impregnating at least a part of thevde
mg at a temperature [between 70° and 120° C.,
gassed Porous block with a polyhydric alcohol so
lution, removing excess impregnant from~ the
block by draining and vby drying at a tempera 10 lacquer by wiping and by
ture substantially between 70° and 120° C., ap
drying at a tempera.
ture of between 75°
plying a relatively thin coating of lacquer to the
vsides of the dried block, and removing excess
lacquer by wiping and by drying at a temperature
of substantially between 75° and 120° C. for sub
stantialiy an hour.
-
'
12; The method of making an electrical‘ con-_
tact element including‘ forming a porous block of
an hour.
‘
and 120° C. for substantially
14. The method of making an electrical 'contact
' element including forming a porous‘ block of
15
?nely divided metallic and graphitic electrically j
conductive material, degassing the porous block
by immersing in a 20% to 40% solution of non-4
electrically conductive material, degassing the
aethylene glycol in water and subjecting the
porous block by- subjecting it to a relatively low
pressure ‘for from one to ;two_hours,- impregnate
block for one to two hours to a relatively low
pressure such that the water of the
.ing' at least a part of thetidegassed porous block
with a solution of nonaethylene glycol in benzene
for from one to two hours, removing excess 'im
with a 10% to 30%’ solution of nonaethylene
pregnant from the block by draining and by dry
glycol in ‘water for from~ one to two hours, re
moving excess impregnant from the block by '
ing at a temperature between 70° and 120° CL, ap
draining and by drying at a temperature between
plying a relativelythin coating of lacquer to the
- 70° and ’120° C., applying a relatively thin coat
sides of the dried block, and removing excess lac
quer by wiping and by drying at a temperature
ing of lacquer to the sides of the dried ‘block,
and removing excess lacquer ‘by wiping and by l‘
01' between 75° and 120° for-‘substantially an hour.
13. The method of making an electrical contact 80 drying at a temperature 01f between 75° and 120°
C._for_substantially an hour. a
4 '1
element including forming a porous block of elec
trically conductive material, degassing the po
CHARLES G. VAN BRUNT.
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