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Патент USA US2404662

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July 23, i
R. H. SAVAGE
ELECTRICAL CONTACT ELEMENT
2,404,62 ’
Filed June 21, 1941
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.
InQen’oor-
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Robert»- H. Sayage',
.119
6.15M”
His Attorneyh‘.‘
2,404,662
Patented July 23, 1946
UNITED STATES PATENT OFFICE
ELECTRICAL CONTACT ELEMENT
Robert H. Savage, vScotia, N. X, .asvsignortp .Gen
eral Electric Company, a corporation of New
York
Application June 21, 1941, Serial No. 399,193
32 Claims. (Cl. 171-325)
1
2
My invention relates to electrical contact ele
ments and particularly to improved contact
brushes and methods of making the 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
vide a lubricant for the contact surface thereof
a porous block of electrically conductive material
provided with a lubricant for the contact surface
thereof.
A further object of my invention is to provide
an improved method of making an electrical con»
greatly increases the life of the porous block,
especially in dry atmospheres. Furthermore, it
have found that under certain conditions and for
certain types of materials, the contact element
is improved by applying to the sides thereof a
coat of relatively thin material Which will not
form a paste with the impregnant of the con
tact element when the brush vibrates and moves
on its guiding surface.
In the drawing, I have shown an electrical con
tact element formed as an electric current col
lectorbrush including a porous block I0 of bonded
tact element.
?nely divided electrically conductive carbona
Further objects and advantages of my inven
tion will become apparent and my invention Will 15 ceous material, such as carbon, graphite, metal
graphite, or other similar ‘material including a
be better ‘understood from the following descrip
tion referring to the accompanying drawing, and
substantial amount of carbon such as is con
the features of novelty which characterize my
ventionally used in the manufacture of contact
invention will be pointed out with particularity
elements, such as commutator and slip-ring
in the claims annexed to and forming part of 20 brushes. A terminal clip II is secured ‘to the
this speci?cation.
porous block ID by a rivet I2 and an electrically
The single ?gure in the drawing illustrates a
conductive pigtail member i3 is secured to the
contact ‘brush for a dynamo-electric machine em
terminal clip I I and to a connecting terminal ele
bodying my invention and made in accordance
ment M for conducting current between a brush
25 holder connector and the contact element block
with my improved method of construction.
It has been found that under normal atmos
In. In order to provide a lubricant to the con
pheric conditions with average ‘humidity, atmos
pheric water ‘vapor provides the best known lubri
cant for the contact surfaces of carbon and
metal-graphite brushes. It has also been found
that electrical contact elements made of porous
tact surface I5 of the'porous block II], a portion
of the block below the terminal clip I I, or the
entire porous block i8, is impregnated with a
pol'yhydric alcohol or alcohol-ether solution.
Among the polyhyd-ric alcohols, which have been
blocks of ?nely divided electrically conductive
found to provide an efficient lubricant for the
material, such as carbon or metal and graphite
brushes, tend to wear away very rapidly in dry
ethylene glycols-to be-particularly e?icient. Mix
contact surface of the brush I0, I have found ‘the
atmospheres. ,In the past different lubricants 35 tures of different polyh-ydric alcohols also have
good lubricating properties. ‘These impregnants
have been suggested ‘for minimizing the friction
are highly "hygroscopic and water soluble and
of the contact surface of the brushes and thereby
have .a relatively Wide liquid state temperature
improving the life of the contact element, but
range. Generally, they also have the desirable
so far as is now known, these various lubricants
do not prevent brushes from wearing away rap
properties of a relatively high ?ash point and Ya
idly in dry atmospheres. Furthermore, most of
relatively low vapor pressure at normal contact
the lubricants which have been suggested dis
element operating temperatures. For certain
advantageously change the electrical character
types of electrically conductive materials, such
istics of the brush or combine with the contact
ascarbon, .electro-graphitic, or natural graphite
element material to form substances which im
pede the free movement of thecontact element
on its .guide member or brush holder, thereby de
creasing the .e?iciency of operation of the com
bination. I have found that impregnating a
porous block of electrically conductive material
with a humectant which has the characteristic of
wetting the brush material even in the absence
of water in the impregnating material, such as
apolyhydric alcohol or alcohol-ether or mixtures
of‘ these in at least a portion of the block, to pro
brushes, I have found a solution of from 10% ‘to
30 % of nonaethylene glycol
in water to be a'very ef?cient impregnant, espe
cially if the metal content of the brush is 50% .or
less. For contact elements wherein the porous
material comprises a'very large amount of metal,
60% or more, I vhave found ‘that an impregnant
55 comprising 40% to 60% nonaethylene glycol and
3
l
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20% to 30% polyole?n glycol in water is a very
e?icient lubricant. '
'
In forming my improved contact elements, I
4
5. A molded electrical contact element includ
ing a graphitic block, and having a portion of said
block impregnated with an ethylene glycol solu
have found it desirable to degas the porous block
tion as a lubricant fOr the contact surface of said
by subjecting it to a relatively low pressure and 5 element.
then impregnating the degassed block with the
6. An electrical contact element including a,
lubricant, after which excess impregnant is re
current collector brush formed of a porous block
moved from theblock, and, in certain cases, a
of electrically conductive carbonaceous material,
relatively thin coating of'material,‘ which does not
and having at least a’ portion of said block im
pregnated with a solution including a polyhydric
react with the impregnant, is applied to the sides
of the dried block. In degassing the porous block,
alcohol as a lubricant for the contact surface of
the contact element is immersed in a solution of
the element.
the impregnant, such as a 20% to 40% solution of _
7. An electrical contact element including a
nonaethylene glycol in water or benzene, and the ' current collector brush formed of a porous car
block is subjected to a relatively low pressure in 15 bonaceous block, and having at least a portion of
this solution for from one to two hours, such
said block impregnated with glycerol as a lubri
that the water or benzene comesto a boil, remov
cant for the contact surface of the element.
ing the gas from the porous block. After this
‘ 8. An electrical contact element including a
treatment, a part or the whole of the'porous block I current collector brush formed of a porous car
is impregnated at substantially atmospheric pres 20 bonaceous block, and having at least a portion of
sure with the solution of polyhydric‘ alcohol in
said block impregnated with a higher boiling
water or benzene for from one to two hours. Ex
point glycol as a lubricant fOr the contact sur
cess impregnant then is removed from the outside
face of the element.
7
of the block in any suitable manner, as by wiping
9. An electrical contact element including a
or draining. The block then may be dried at a 26 current collector brush formed of a porous car
temperature between .70" and 120° C. to remove ,
bonaceous block, and having at least a portion
water from the brush and to provide the desired
of said block impregnated with polyole?n glycol
concentration of impregnant. “As stated above, .
as a lubricant for the contact surface of the ele
with certain porous materials, it is desirable to
provide a very thin coating of non-paste form
ing material over the sides of the block. I have
found that a thin coating of metal of between 5
and 10 mils thickness applied to the sides of the
ment;
10. An electrical contact element including a
current collector brush formed of a porous block
of electrically conductive carbonaceous material;
and having at least a portion of said block im
pregnated with a hygroscopic humectant mate
as by the Schoop process provides an ef?cient low 35 rial characterized by the property of wetting said
friction surface ‘which will not form a paste with
brush material in the absence of water in said
the impregnant, even after long periods of use
impregnating material.
'
‘
block by spraying molten metal under pressure,
and vibration over a supporting or guiding sur-.
11. An electrical contact element including a
face. This metal preferably is of relatively high
current collector brush formed of a porous car
electrical conductivity, such as copper, and may 40 bonaceous block, and having at least a portion of
or may not be porous. A metal coating of this
said block impregnated with a highly hygroscopic
type provides a relatively hard guiding surface
material characterized by the property of wetting
for the brush on its brush holder and effectively
said carbonaceous material of said brush in the
prevents sticking of the brush in the holder.
absence of water in said impregnating material
=While I have illustrated and described par- ‘
and having a relatively low vapor pressure at
ticular embodiments of my invention, modi?ca
normal contact element operating temperatures.
tions thereof will occur to those skilled in the
12. A brush element including a porous car
art( . I desire it to be understood, therefore, that
bonaceous block of ?nely divided electrically con
my invention is not to be limited to the particular
ductive material, a humectant in at least a por
arrangements disclosed, and I intend in theap
tion of said porous block, and means including a
pended claims to cover all modi?cationswhich do
relatively thin coating on the sides of said block
not depart from the spirit and scope of my in
for preventing the formation of a paste by said
humectant and said ?nely divided material.
' What I claim as new and desire to secure by
13. A molded electrical contact element includ
ing a graphitic block, and having a portion of
Letters Patent of the United States is:
.
said block impregnated with nonaethylene glycol
4 1. An electrical contact element including a
vention.
I
_
‘
current collector brush formed of a porous block .
as a lubricant for the contact surface of said
of ?nely divided electrically conductive carbona
element.
.
14. A brush element including a porous block
ceous material, and a solution comprising ethyl
ene glycol solution in at least a portion of said 60 of electrically conductive carbonaceous material,
and having at least a portion of said block im
porous block.
,
'
a ‘2. A molded electricalcontactelement includ
pregnated with an alcohol-ether solution‘ as a
lubricant for the contact surface of the element.
ing a block of ?nely divided carbon, and an ethyl
15. A brush element including a porous car
ene glycol solution in at least a portion of said 65
bonaceous block, and having at least a portion of
block.
'
‘
said block impregnated with a highly hygroscopicv
3. An electrical contact element including a
material characterized ‘by the property of wetting
current collector brush formed of a porous mem
the porous material of said brush in the absence‘
ber of ?nely divided bonded carbonaceous mate
of water in said impregnating material and hav
rial, and an ethylene glycol solution in at least 70 a relatively high flash point.
a portion of said porous member. > _
16'. An electrical contact element including a
r. 4. An electrical contact element including a
porous block of ?nely divided electrically con
porous graphitic block, and an ethylene glycol
ductive carbonaceous material, at least a1 portion
impregnated into at least a portion of said porous
of said block being impregnated with a highly
block..
-
'
.
75' hygroscopic lubricant for. the contact surface. or,
2,404,662
5
said element, and means including a relatively
thin coating on the sides of said block for pre
venting the formation of a paste by said impreg
nant and said ?nely divided material.
17. An electrical contact element including a
porous block of ?nely divided electrically con
ductive material, at least a portion of said block
having a liquid lubricant therein for the contact
surface of said element, and means including a
coating on the sides of said block having the 10
characteristics of a coating applied by spraying
under pressure on the sides of said block for pre
venting the formation of a paste by said im
pregnant and said ?nely divided material.
6
ing of material non-paste forming with the im
pregnant.
,
27. The method of making an electrical con
tact element including forming a porous block,
impregnating at least a part of the porous block
with a polyhydric alcohol solution, and applying
by spraying under pressure a relatively thin coat
ing of metal to the sides of the impregnated
block.
28. The method of making an electrical contact
element including forming a porous block of elec
trically conductive material, degassing the po
rous block by subjecting it to a relatively low pres
sure, impregnating at least a part of the degassed
18. An electrical contact element including a 15 porous block with nonaethylene glycol, removing
excess impregnant from the block, and applying
to the sides of the dried block a relatively thin
porous block of ?nely divided electrically conduc
tive carbonaceous 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 means in
cluding a relatively thin coating on the sides of
coating of material non-paste forming with the
impregnant.
,
29. The method of making an electrical con
tact element including forming a porous block
of electrically conductive material, degassing the
said block for preventing the formation of a paste
porous block by subjecting it to a relatively low
by said impregnant and said ?nely divided ma
pressure, impregnating at least a part of the de
terial.
gassed porous block with a polyhydric alcohol so
19. An electrical contact element including a
lution, removing excess impregnant from the
porous block of ?nely divided electrically con
block,
and applying a relatively thin coating of
ductive material, at least a portion of said block
metal to the sides of the dried block.
having a lubricant therein for the contact sur
30. The method of making an electrical con
face of said element, and a metallic coating on
the sides of said block having the characteristics 30 tact element including forming a porous block of
electrically conductive material, degassing the
of a coating applied by spraying under pressure
porous block by subjecting it to a relatively low
on the sides of said block.
pressure, impregnating at least a part of the de
20. An electrical contact element including a
gassed porous block with a solution of non
porous block of ?nely divided electrically con
aethylene glycol and polyole?n glycol, removing
ductive carbonaceous material, at least a portion
excess impregnant from the block, and applying
of said block being impregnated with a polyhydric '
to the sides of the dried block a relatively thin
alcohol solution providing a lubricant for the
coating of from 5 to 10 mils thickness of mate
contact surface of said element, and a metallic
rial non-paste forming with the impregnant.
coating on the sides of said block.
31. The method of making an electrical con
21. A brush element including a porous block 40
tact element including forming a ‘porous block of
of electrically conductive material, and an im
electrically conductive material, degassing the
pregnant in at least a portion of said block com
porous block by subjecting it to a relatively low
prising a solution of nonaethylene glycol and
pressure for from one to two hours, impregnat
polyole?n glycol in water.
22. A brush element including a porous block 45 ing at least a part of the degassed porous block
with a solution of nonaethylene glycol in benzene
of electrically conductive material, and an im
for from one to two hours, removing excess im
pregnant in at least a portion of said block com
pregnant from the block by draining and by dry
prising a solution of substantially 50% non
ing at a temperature between 70° and 120° C., and
aethylene glycol and substantially 25% polyole
50 applying to the sides of the dried block a rela
?n glycol in substantially 25% water.
tively thin coating of from 5 to 10 mils thick
23. A brush element including a porous block
ness of material non-paste forming with the im
of electrically conductive material, and an im
pregnant.
"
pregnant in at least a portion of said block com
32. The method of making an electrical con
prising a solution of substantially 30% non
55 tact element including forming a porous block of
aethylene glycol in water.
?nely divided metallic and graphitic electrically
24. The method of making an electrical con
conductive material, degassing the porous block
tact element including forming a porous block,
by immersing in a 20% to 40% solution of non
degassing the porous carbonaceous block, and
aethylene glycol in water and subjecting the
impregnating at least a part of the degassed
porous block with a polyhydric alcohol solution. 60 block for one to two hours to a relatively low pres
sure such that the water of the solution boils, im
25. The method of making an electrical con
pregnating at least a part of the degassed porous
tact element including forming a porous block,
block at substantially atmospheric pressure with
impregnating at least a part of the porous block
a 20% to 40% solution of nonaethylene glycol in
with a polyhydric alcohol solution, and applying
to the sides of the impregnated block by spraying 65 water for from one to two hours, removing ex
cess impregnant from the block by draining and
under pressure a relatively thin coating of mate
by drying at a temperature between 70° and 120°
rial non-paste forming with the impregnant.
0., and applying to the sides of the dried block a
26. The method of making an electrical con
relatively thin coating of from 5 to 10 mils thick
tact element including forming a porous block,
degassing the porous block, impregnating at least 70 ness of material non-paste forming with the
impregnant.
a part of the degassed porous block with a poly
ROBERT H. SAVAGE».
hydric alcohol solution, and applying to the sides
of the impregnated block a relatively thin coat
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