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Aug. 13, 1963
Filed July, 22, 1958
L/ 22
United States PM o r‘ice
PatentedAug. 13, 1963
_ .-
vpacked within a capacitor housing. A further considera
tion of capacitor terminal connections‘involves the inter
mediate product during processing. Regular manutac
Llvlllgston L. Rice, Williamstown, and Donato F. Dagnoli,
North vAdams, Mass, assignors to Sprague Electric
Company, North Adams, Mass, a corporation of Mas
_ turing ‘procedures require the handling of partially com
pleted or uncased assemblies. In these assemblies the
, lead wires'are attached to capacitive sections prior to
?nal encasement. In such condition they are vulnerable
Filed July 22, 1958, Ser. No. 750,139
2 Claims. (Cl. 317-260)
7 to the shocks with
which the manutacturing procedures
are fraught. '
invention relates to convolutely wound electrical
It is an objectv of-this invention to provide a terminal
connection for capacitors in which the above'rela-ted dis
advantages are eliminated or avoided.
Convolutely wound capacitors made
of two electrode ‘
It is another object of this invention to provide‘a con
foils of opposite polarity and separated by sheets of di
. volutely wlound capacitor'h-aving a connection between
electric material are Wound into a compact form; in which 15 the terminal‘ lead wire and the thin electrode foils which 1
capacitors and more particularly to lead wires ?or capac
thin foils of opposite polarityv are wound inhalternate'
layers and separated by intervening thin dielectric‘ ?lms
‘is resistant to physical shock and vibration.
‘ '
' It is a further object of this invention to provide a
or ribbons. ‘Capacitor lead wires are attached ‘axially
into the convolutely Wound capacitors ‘to connect, the re
capacitor lead. wire. which gives partially under an end
tively connectable at opposite ends otthe cylinder shaped
‘ ‘means and method of mounting of a lead wire in a con
wise pull without’lo‘ss'of electrical connection or dis
spective toils of the capacitor into electrical circuits. 20v ruption of the capacitor structure.
Generally the alternate foils are wound so as to be respec
_It is‘ a further,’ object of this invention to provide a
‘' capacitor.V
The respective lead wiresl attached
volutely wound capacitor'by conventional means to pro
duce a finished capacitor in which the lead is secured and
maintains "electrical contact despite some axial displace
at the respective‘ends each makecon-tact with one of the"
respective foils._ ,Each‘ lead wire must be attached into the
capacitor in ‘such a manner as to maintain permanent elec~
trical contact with itsrespective thin l?oil,
A severance of the connection of ‘the lead wire from
These and other objects of‘ this invention will be more
clearly understood front the following description taken
the capacitor foils ‘disrupts the function of ‘the capacitor '
' togetherwith the accompanying drawings in which: ,
Vanda-generally destroys its use. Lead wires are of neces 30 ‘ FIG. 1 is a sectional view of a convolutely wound capac
sity subject to certain tension or pull. I Accordingly, it is
, itor assembly having a lead wire of this invention;
a problem in the use of capacitors to avoid the destruction
“FIG. 2 is-a vertical elevation of the 'end of a lead wire
of the capacitor by pulling the lead Wire out of ‘the
capacitor and severing the electrical connection as Well
as mangling a part of the conv'olute windings.
For these
reasons, it is desirable that a-lead wire be. capable of
of this invention;
pulled out lot‘ the capacitor completely and losing itsvcon
‘ tact with the eleetrode foils.
7‘ It is important that the‘ electrical connection between
the lead Wire and the respective electrode toil be perma
nently maintained in each and every ‘unit. The discon-i
nection of either lead wire in any capacitor construction
may be a matter of consequence.
form of lead wire anchored in the capacitor assembly; and
invention a convolutely wound capaci
that the connection between a lead wire and-its respective
, electrode foil is not‘ severed or otherwise broken by par
displacement of the lead wire and shock or _vibra-,
tion and the lead wire is secured in the capacitor assembly
ponentsfor the purpose of maintaining the electrical con
nection with the lead wire is not feasible. Similarly, it
is not possible to assume a permanent connection by the 50
Further, in some capacitor constructions the main-tea .
capacitor assembly in complete form showing another
I According to
‘and the augmenting of the physical strength of thecoms
FIG. 4 is a plan view oft e end of the lead wire taken
along the line IV--IV of FIG. 2;
‘ FIG. 5 is a sectional view {of another convolutely wound
tor‘ has lead Wires which are connected-in such a manner
so that the components are of relatively frail materials
I FIG. 6 is a sectional View of the capacitor assembly of
At the same time, '
addition of other connection means such as additional
V FIG. 5 as wound together and in uncompleted form.
capacitors of this invention are limited in size and weight
this invention;
withstanding a certain amount of strain without‘ being I
' '
.FIG.‘ 3 is a perspective view of a terminal lead wire of
against easy removal.
The convolutely wound capacitor incorporating this
* invention is impregnated with anv impregnant which;
becomessolid upon impregnation into the'capacitor. The
nance of electrical connection between the capacitive sec; '
tion and the lead wire is assisted by the casing and hous» .
ing in which the capacitive section is contained. There are capacitor constructionslacking this outer structural _
containment‘and support. In such uncased units the re
tention of the lead wire is aggravated by the absence ‘of
lead wire incorporated in this convolutely wound solid
impregnated capacitor is securely held in the capacitor by
the solid impregnant. The lead Wire is formed so as to
be anchored in the capacitor by a part of the lead wire
and to be freely moving with respect to another part of
the lead Wire. a The lead'wire is provided with a loop or
curlicue described in a plane generally radial to the axis
structural help of an ‘outer casing. At the same time, so of the capacitor. This‘loop divides the lead .wire into
the connection between the lead Wire and the thin elec~
two parts having relative mobility with each other. One
trode vfoils in a cased capacitor unit is subject to disrup
of the relatively movable parts is gripped ‘inthe COD-.
tion. While the‘ casing serves to insulatethe components
volutely wound capacitive section by the solid impregnant.v
within its exterior from exterior shock a certain amount
Another part of the lead wire of this invention is separated
of strain is possible between the components within the 65 ?rorn the anchored partby the intermediate loop. ‘This
casing. This interior strain is'rnost likely to occur at the
connection between the‘ lead Wireand the thin electrode
foils. For example, a capacitor might be mounted in a
situation where it was subject ‘to constant, violent vibra 70
tion which over a substantial period ottime could cause
a loosening ‘of components even-as "to thosejthiat are"
other-‘part includes ‘the exterior part of the lead wire.
Thus,v it is possible for the loop to allow an unwinding
and uncoiling of the terminal lead wire over an axial
pull of the long arm part of the lead wire.
- "
' '
It is a ‘feature of this invention that the external part
of the lead wire is movable withvrelation to the other part
" 3,100,857
16 in the convolutely wound assembly. ' lI‘he impregnant i
of the lead wire and the remainder of the capacitor con
serves the other customary functions of an‘ impregnant
including the ?lling of voids. The impregnated capacitor
struction without severingrits‘ electrical connection to these .
parts or completely losing its grip inthe capacitor.
Referring to FIG. 1 a capacitor assembly is shown made‘
up of a pair of convolutely wound foils 10-and 11 sepa
rated by dielectric strips 12. and ‘13, also convolutely
wound. The foils alternate with the dielectric strips in
with the leads gripped in place may be subsequently
encased for use in an outer casing of a mineral ?lled
thermoset resin such as phenol formaldehyde, also urea
formaldehyde, urea melamine, alkyds such as the product
the conventional manner so that the foils 10 and 11 are
of phthalic anhydride and glycerol compression molded‘
insulated from each other. The dielectric strips and the
silicone and epoxy types may be molded into an encase
electrodes are wound so that'one edge of each of the foils 10 ment.
The capacitor structure of this invention when com
10 and 11 extends from opposite sides of the dielectric
pleted is made up of the convolutely wound assembly with
?lms --12 and 13 in accordance with'the conventional non
lead wires 16 positioned on the respective ends- and an
' inductive construction of convolutely. wound capacitors.
in situ polymerized irripregnant gripping the lead wires to
, A lead wire ,16 is attached at each end ofthe capacitive ‘
section. The contact ‘of the lead‘ wires 16 is made each 15 the assembly by suitable adhesion of the solid impregnant
to the tail portion 18 interposed into the wound assembly.
' H with one of the respective foils 10 or 11 at the respective
This structure may or may‘ not be contained in a casing.
or jacket. The capacitive section and lead wires assem
of atail section 18, an externally extending section 19,
blies may also be .used‘as an unencased unit. vIn such
and' a radial loopi20. vThe ‘radial loop overlies and .
'contactshthe extended foil edges at its‘ respective end of 20 a construction the outer casing is omitted and the value
ends of the’capacitor.
Each of the leads 16 is made up
of the arrangement of this invention is magni?ed. When
this invention is incorporated into an uncased unit ‘the
the capacitor., Each tall 18 projects into the convolutely
wound construction at the centenwIn the interleaved
function of the loopZG, serves to replace some of the
function performed by a capacitor casing particularly
the initial turn is of the dielectric material alone. 'The
tail 18 is interpositioned in these central turns‘ of the 25 in avoiding‘ the, effect-‘of shock, vibration and physical dis-v
placement at the connection between the lead wire and
dielectric material, and thus neither tall 18 is in contact
the capacitive- section. :This" same function of the inven
with electrode foils 10 and 11. v
convolutely wound assembly of foils and dielectric ?lms »
tion is employed in protecting‘ the assembly during the
In vFIG. 2 :an elevation of part of the lead wire16
manufacturing process and before encasement.
“shows the tail ‘18 and externally extending section 19
joined by radialloop 20. The tail 18 and the external‘ 30' £[n theruse of the capacitor structure of this invention,
thestructure is attached into an electrical circuit by hav
section‘19 are connected only through the loop 20. .. The
ing the leads suitably connected. The capacitor during
loop 2'0is formed in the lead by a process which shortens
‘ its use both before and afterconnection into an electrical
a length of straight lead wire. This foreshortening may
circuit has in?icted upon it through the leads various phys
be achieved by any method which creates the loop 20
These may range from simple handling of
between the two straight sections.
' 35 ical strains.
the structure to a forceable endwise pull on the lead.
;In 'FIG. 3 the'relative axial disposition of the‘ two ends,
The respective tails 18 are gripped in the wound assem
tail 18, and external section'19 of the lead wire 16 is
.:bly and the external sections 19 are partially independ
. illustrated; The curlicue nature of'the loop 2.0 places the
ently movable with respect to the wound assembly and the
tail 18 and the section ,19 in general axial alignment but
,in complete physical disconnection except for the inter 4.0 tail 18. Vibration, pull and other dislodgement or dis
turbances of one of the lead wires may result in substan
mediate loop 20. .As shown in FIG. 3 the loop 20 is
tial movement of the external section I19‘ of the wire.
essentially perpendicular in outline. The axially extend
This disturbance is ?rst translated to the loop 20. At the
. ing tail 18 and external section 19 both axially leave the,
loop 20 the effect of the disturbance on the capacitor struc
plane of the loop 20 at approximately the same area. As
shown in FIG. 3 and in FIG. 4 this point of axialdepar 45 ture is absorbed. Because in the loop 20 the lead reverses,
ture- is central of the loop 20. As a result both the tail
18' and external section 19 are oriented along lines per
pen-dicular to the radial plane of the loop.
on itself, the portion of the loop most-adjacent the exter-'
nal section 19 may be moved but it will not be moved
> axially out of contact with the electrode foil rwithout sub
stantially more than normal amount of physical dislodge
leads 16 seat against‘ the extended foils at their respective 50 ment. In some constructions the lead wire is secured to .
/ Referring again to FIG. 1 it is seen that the respective
ends of'the convolutely wound assembly. 'In this position
each radial loop 20 lies against the ‘foils in a substantially
radially extending position with respect to the wound
assembly. With the respective leads thus positioned, the
tail 18 and the external section 19 are oriented coaxially 55
with the wound assembly. The'tai'l 18 is inserted into
the centr'aPdielectric turns of the assembly as indicated’ '
at A and B. {The external section 19 of each of the leads 7'
extends along the same line outward from the end of they
wound assembly and. therefore axially in the manner of 60
conventional lead position for this type of capacitor con
struction. The radial loop 20 in eifect extends radially
from these lines of orientation of the tail 18 and the
“ external. section 19. _ The loop lies over the end of the
the electrode, foils by a solder connection in which a de
posit of solder is ‘attached to both the lead wire and’ the
respective electrode foil. in subesquent treatment of the
resultant assembly this solder ‘deposit may be pulled away
either from the lead or from the foil. [In the device of‘
this invention such a pulling away of the solder, is as for‘
example with uncoiling of the loop, is counteracted both,
bythe resistance to such pull which is offered by the an
choring tail v18 and also by a section of the loop 20- re
maining in low resistance contact with the respective elec-‘
trode foil. The partial uncoiling of the loop 20 still
leaves enough of the loop 20 in contact with the extended
foil to maintain good electrical contact.
As a result the leadv wires 116 may be subjected to an
respective extended edges of several turns of the respec 65 end pull of several pounds without disconnecting the con
fact with the respective vfoil. The pull will cause the ex
tive foil and maintains contact therewith. The lead is
looped or bent so as to be reversed on itself at least once’
. ternal section to move'axially of the assembly but will not
result in adisengagement of the respective tail, .18 from_
the'wound assembly. The assembled capacitor structure
lThe ?nished capacitor assembly with leads 16 in posi 70 with the solid impr‘egnant holding the lead lwires 16in
and ‘from at least one 180° angle. In the embodiment
illustrated,- thelead forms a complete 360° arc._
tion as described above is impregnated with an impregnant
which is polymerizable in situ to the solid state. A suit
able impregnant whichpolymerized to a solid is N-vinyl
carbazol which may be'polymerized inv situ to form a
solid impregnant gripping the tails 18 of the lead wires 75
the wound assembly is capable of taking substantial phys
ical disturbance at the lead wires. ‘In normal use, the
amount of axial pull-exerted on the leads of a capacitor
will notjexceed the limit of pull which'can be tolerated
by the looped lead wire construction of this invention.
Consequently, capacitors will not7be pulled apart when, _, _ ; At the center the mandrel628‘ has embedded
the lead wire incorporatesthe loop described herein.
’ pair of oppositely extended leads 29‘ and 30. The ileads
It will be seen thatamong other vadvantages the'c'o'né
struction of this invention serves to interpose a shock'ab
.291and 30 extend axially from the capacitor 21 at the
respective ends thereof. A head 3i1on~each of the respec
sorber between ‘the sections of the lead wire. The por-'
_ 5 tive leads 29 and 30 are embedded therein. A pair of;
tions which are in contact with the electrical foils and
conducting tabs 32 are inserted into the body of the in
which are more subject to physical movement are secured ‘
, in the wound assembly or isolated from the portions of the
lead wire.
' .terieaved foils 22 and 23 and ribbons 24 and 25 so that ’
one‘is connected to [foil 22 and‘ the other is connected
As a result‘the completed capacitor will with- . . to foil 23. The tabs 32 extend diametrically from the
stand considerable Ivibration and-shock.‘ The electrical 10 convolutely wound ‘capacitor body and have freeends
ef?cacy of the capacitor will not :be impaired by an end
wise movement of the outer portion of the lead wire, such
attached to the respective lead 29 or 30. The capacitor '
21 is assembled to ‘ the partially. assembled condition
shown in FIGURE 6 in the following manner. The thin
I as would utterly destroyia device‘of ‘the prior art.‘
This invention substantially reduces the occurrence of
strips 26 and 27 of polystyrene are wound aroundthe man
capacitor failure due to lead loosening. This is an advan 15 drel 28 to form a tube shape'aroundia central passage 3-3.
tage as little foil is provided fror'ancho'ring the lead wire
in some capacitor constructions, and in some uses thefail
ore of a‘ single capacitor is of paramount concern. ' lFur
The leads 29 and 30 are inserted in opposite ends of the
hollow mandrel 28, each having its head 31 inserted sub
stantially into the mandrel 28.
ther, a better connection is provided with no extra ma
The inductive winding ’
of the capacitor 21 consisting of the alternate layers 22,
terial, thus assisting light weight‘ considerations. The 20 V24, 23, 25 is interleaved, with‘ the polystyrene strips 26
capacitor unit with the invention withstands shock and
‘and 27 and, wound with the interleaved polystyrene her
vibration.v Further, some'axial movement of capacitor
a few turns around the mandrel 28‘. i
leads can now be tolerated without loss of electrical pro?
It is pointed out above that strips 26and 27 terminate
so that the outer turns are made up of the ribbons 24 and
25 in the toils 22 and 23* convolutely wound. The assem
bly is then cured at a temperature high enough to cause
In the illustrated embodiment of this invention the ex
ternal section 19 extends axially from the capacitor sec
The construction can be modi?ed and the external
i the polystyrene ?lm and mandrel to- shrink’ around the
section 19 may be extended radially of the capacitance
section on being bent down parallel to the loop 20. This
construction has the same advantages as-the axially ex
tending construction in being capable of withstanding. a
greater pull than previous leads.
leads 29 and 30 and their heads 31 so thatthe leads 29
' and 30 are embedded in- the polystyrene layers 26, 27 and
30 the mandrel 28 and securely gripped therein. The strips
26 and 27 p and the mandrel 28 are fused and joined by
‘It will be understood that the above-described embodi
ment has been set forth for the- purpose ‘of illustration
only and that this invention can'be incorporated in vir
theshninlcage of heating. Then the ends of the tabs 32
are clamped around the respective adjacent leads and
either‘welded or soldered to the leads 29 and 30 to pro
vide an electrical connection between the respective leads
tually all convolutely wound capacitors whether made up
and foils.
of a strip of paper, ?lm or other combination of these
The resultant ?nished construction is such as shown in
dielectrics. ' It is a feature of this invention that the .solid
FIGURE 5. At the center of the capacitor 21 the poly
impregnant in thelcon'volute windings looks around the
styrene. is a plug 28 which is c?used to the shrunken strips
tail 18 to secure the lead wire in the convolute windings. 40 26 and 27. The plug 28‘ is embedded therein the heads 31
This impregnant is not limited to the Ndvinyl carbazol
of the leads 29 and 30 which extend diametrically from
mentioned above but ‘may be vany which will polymerize
the plug 28 and with other ends of the capacitor 21. The
in situ to the solid state,‘ such as polystyrene as well as its
polystyrene plug 28‘ is fused to surround and contain
copolym'ers, polyesters such as, for example, ‘the copoly
the leads 29 and 30 which are retained therein. The cur~
mer of bisphenol, hexalene glycol, dibenzylic acid and
ing step for shrinking the polystyrene around the nail
itaconic- acid. Other modi?cations include the material
heads 31 is carried ‘out at approximately 150° C. for 45
of the dielectric spacers which need not be calendered i ‘ to 75' seconds. The time variation depends upon the
ma paper but may be made up of resinous (?lms. Simi
size 'of the unit constructed and the resultant period neces-v
larly though foils have been indicated in the figure. and de
sary for obtaining satisfactory shrinkage of the poly
scribed, rnetallized dielectric ?lms are equally satisfactory 50 styrene.
for this purpose. The metallized layer would be imposed
A modi?cation of the described embodiment may be
on the surface of the paper spacer. ‘In the capacitance _ had by a pie-assembly of the nail head leads in a plug
section the metallized layers would alternately extend
of polystyrene material whichiuis shrunken onto the nail
from alternate ends of the wound assembly. ‘
' '
head leads. The plug-leads sub-assembly thus formed
IIn FIGURES 5 and 6 capacitors are shown in which
axially extending leads are anchored in convolutely wound '
capacitance sections. 'In FIGURE 5 an assembled capac
itor 21 is shown made up of a pair ,of’metal foils 22 and
23 wound ‘between ribbons of suitable dielectric such as
may receive the alternate foils and resin ribbons of the
capacitor assembly which are convolutely wound around
the plug-leads combination which thus takes the place
of the mandrel as described above in the assembly of
the ‘capacitor.
The'convolutely wound section of the
Mylar ‘(a polyterephthalate resin of Du Pont Company,
Wilmington, Delaware), and polystyrene. Ribbons 24
' capacitor may be impregnated such as for use at interelec
and 25 of Mylar alternate with the foils 22 and 23 in con-'
pregnaited for higher voltages. Suitable impregnants are
mineral oil, silicone'oils (such as those described in the
ventional manner so that ‘the ‘foils are insulated from
each other land can be oppositely polarized. Strips 26
trode potentials of 100 volts ‘or less, or they can be im
Obenhaus US. patent application Serial No. 591,065, ?led
and 27-of polystyrene are wound around mandrel 28 at 65 June 13, 1956), chlorinated diphenyl, chlorinated naph
the center of the capacitor 21. The strips 26 and 27
are interleaved with the ribbons 24 and 25 and the foils
22am! 23‘. ‘In the assembly of the capacitor 21 this is
tlralene, castor oil, and the polymer described in U.S.
Patent 2,711,498, granted June 21, 1955.
The above-described embodiments of capacitor terminal
accomplished by ?rst winding the strips 26'and 2f] around
connections have been set forth for the purpose of illus
the mandrel 28 alone and then interleaving strips 26 and 70 tration. ' It is intended. that the -following claims de?ne
27 with ribbons 24 and 25 and foils 22 and 23. When
the end of strips .26 and 27 have been reached the wind
ing of these strips terminates so that the interleaved layers
the scope.
What is claimed is:
l. A ‘capacitor comprising a convolute winding of a
are of alternate ribbons 24 and 25 interleaved between 75plurality of electrodes with ‘dielectric material therebe
the alternate foils ‘22 and 23.
tween, ailateral edge of one electrode of said plurality
tion being impregnated with a solid dielectric‘material,
’ extending beyond an end of saidelwinding, a lead-lwire
hay‘ing'a ?rst end and 1a seoondend and an intermediate] ' said ?rst endwoif said leaddwire being secured in said solid
dielectric material
said eoiled portion being joined ' i
pomo'n donniediimd a loop substantial-1y nonmal to said:
to said extended foil over substantially the entire eXtent‘
?rst end,‘ said lead-Wire :secured to said Winding with said
first end within'lsaid dielectric -material- and with said
loop in electrical ‘contact with‘ said extending edge, where
Of the coil, whereby an elongating force on said second‘
end Will eifect unwinding'of said ooiledpdrtion i-n ‘prefer
ence to disengaging said lead-Wire- from said section.
' by a force applied/to said second‘end will uncoilsaid
loop'befone disengaging said‘lead-Wire from said wind
References Cited in the ?le of this patent
- 2'. Ani'electrical capacitor comprising a capacitance
section’ ‘having electrode rfoil's convolutely Wound and
‘separated ‘by dielectric spacers, a lateral-edge of me of
said ‘foils extending‘ beyond an end of said seotion to
penmit electrical connection thereto, a lead-wire having ‘
a ?rst end substantially coanial with a second end, a por
tion of said lead-wire between said ?rst end and said
second endbeing ‘coiled substantially radially, said sec
, Knudsen ____________ __~__ May 29, 1934
‘Paules _______________ -QJuly 19, 1949
_ Barnard 61118.1 ______ _1____ Dec. 25, 1951
’ Shrider __;_ ____ _-_ ____ __>__ Jan. 7, 19517
GreatBrita'iln' _________ __ Nov. 17, 1954
Patent No. 3, 100,857
August 13, 1963
Livingston L, Rice et a1 .
It is hereby certified that error appears in the above numbered pat
ent requiring correction and that the said Letters Patent should read as
corrected below.
Column 1, line 65, for "exterior", first occurrence, read
—— interior ~—; column 8, list of References Cited, under
the following reference:
Bur1ingame—-~——Aug. 13, 1935
Signed and sealed this 28th day of April 1964.
Attesting Officer
Commissioner of Patents
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