Adjustable width caps for insulating series loops on bar wound armatures in electrical systems

The cap for the series loop includes a pair of identical cap sections each having side walls, an end wall having first and second segments offset in a longitudinal direction and a cover extending between the side walls and from the end wall on one side of the cap. A longitudinally extending tab lies adjacent one side wall defining a slot for receiving an opposite wall section of the other cap section when assembled. In assembly, the side walls and end wall segments of the respective cap sections are respectively intermeshed to form an enclosure open at one end for receiving the series loop, the enclosure being adjustable in width depending upon the magnitude of the intermeshing of the sections.

BACKGROUND AND SUMMARY OF THE IVNENTION 
The present invention relates to a molded cap for insulating series loop 
connections on bar wound armatures of electrical systems, for example, 
generators, and particularly relates to a pair of homomorphic sections for 
assembly to form a cap enclosure of selected width to accommodate 
variations in series loop dimensions which would otherwise require caps of 
different sizes. 
Molded caps for insulating series loop connections in electrical systems, 
for example, turbo-generators, have recently, in many applications, 
replaced resin-filled mica tapes previously wrapped about the series loop 
connections. Notwithstanding the use of new molded caps for this purpose, 
electrical systems, including generators, are currently being designed 
with series loops on their armatures having shapes which are very 
difficult to tape or accommodate in a particular molded cap. While the 
caps have afforded large cost savings in time and materials and higher 
quality series loops, the molded caps heretofore have the disadvantage 
that different size caps are required for different size series loop 
connections. This has led to high tooling costs to make caps of different 
sizes and, as a consequence, the molded caps, while an improvement over 
the resin-filled mica tapes, have been applied only to high-production 
electrical systems. Stated differently, because of the lack of dimensional 
commonality in electrical systems design, the application of a particular 
sized cap to series loops is limited. At the same time, it has become 
increasingly desirable to apply molded caps to conventional electrical 
systems such as generators, including older generators when they are 
rewound. 
Conventional molded caps are essentially five-sided boxes each having a 
pair of opposed side walls, an end wall, and covers spaced one from the 
other along opposite sides of the cap, leaving an open end through which 
the loop may be received. The caps are conventionally molded from 
glass-reinforced thermoset materials. To install these conventional caps, 
they are generally filled with a thermoset potting compound and pushed 
over the series loop. In certain instances, the potting compound is 
injected into the cap after it has been placed on the series loop. 
A clamshell-type cap has also recently been designed and has the advantage 
of requiring less filler material and a less massive series loop. However, 
the clamshell design is less versatile than the conventional molded cap 
and is generally contoured around the series loop such that relatively 
little variation in loop size may be accommodated. Because it cannot be 
pushed axially over the series loop as a conventional cap, additional 
clearance between adjacent series loops is necessary. Significantly, 
tooling costs are much higher for the clamshell-type cap because the two 
halves require two different molds. 
According to the present invention, there is provided a molded cap formed 
of two identical or homomorphic cap sections which, during assembly to 
form a series loop cap enclosure, are adjustable in width to form a cap 
enclosure for receiving a number of different sized series loops. For 
example, while the length and height of the series loops are very closely 
related, the width of the loops vary greatly between otherwise similar 
designs and particularly vary according to the type of the series loop 
connection. For example, a series loop with a strand-to-strand braze is 
much narrower than a series loop with a single-shot braze connection, the 
latter being about twice as wide as the strand-to-strand braze, although 
their length and height dimensions are similar. Thus, the present 
invention provides a molded cap formed of two identical cap sections 
which, during assembly, are adjustable in width to accommodate different 
designs of series loops. 
To accomplish those ends, two identical cap sections, formed of dielectric 
material, are assembled together to form a five-sided enclosure with an 
open end for receiving the series loop. Each cap section includes a pair 
of spaced side walls, an end wall interconnecting the side walls at one of 
the section and a cover extending between the side walls and from the end 
wall along one side of the cap section, leaving free the margins of the 
side and end walls along the opposite side of the cap section. To permit 
assembly of the two cap sections to form the cap, each end wall has first 
and second generally parallel segments offset longitudinally one from the 
other. These segments have edges inset from the free margin of the end 
wall at a location substantially medially of the length of the end wall to 
define an inset portion or opening extending at least equal to one half 
the depth of the end wall. Additionally, a longitudinally extending tab is 
disposed adjacent to one of the side walls in generally parallel relation 
therewith and adjacent the end wall to define a slot with the one side 
wall for receiving an opposite side wall portion of the other cap section 
when the cap sections are assembled. A rib also projects inwardly from the 
opposite side wall at a location from the end wall a distance in excess of 
the length of the tab. The tab has an opening and the opposite side wall 
has an opening for facilitating securement of the sections one to the 
other as set forth hereinafter. 
To assemble the cap sections to form the cap, the side walls and end wall 
segments are respectively intermeshed or nested whereby the cap sections 
in final assembly are transversely offset a distance corresponding 
substantially to the width of a side wall while simultaneously aligned in 
the longitudinal direction. Thus, the side walls of a first cap section 
lie in generally parallel juxtaposition with the respective side walls of 
the second cap section. More particularly, the first side wall of the 
first cap section lies outwardly of the corresponding second side wall of 
the second cap section while the second opposite side wall of the first 
section lies inwardly of the first opposite side wall of the second 
section. Additionally, the second side wall of the first cap section has a 
portion which lies between the first side wall and tab of the second cap 
section while the second side wall of the second section has a portion 
which lies between the first side wall and tab of the first cap section. 
The first and second end wall segments of the first section lie in 
side-by-side generally parallel relation with the respective second and 
first end wall segments of the second section. The inset edges of the 
first and second segments of each end wall defining the inset portion 
medially of the length of the end wall enable an intermeshing of the first 
and second segments of the end walls of the respective cap sections and 
the respective side walls. The covers of the first and second sections lie 
in spaced opposition one to the other. Thus, the covers, side walls and 
end walls define a generally five-sided enclosure open at an end thereof 
opposite the end walls for receiving the series loop of the armature. 
It will thus be appreciated that, when assembling the cap sections, the 
covers may be selectively spaced one from the other, depending upon the 
extent to which the side walls and end walls intermesh. Thus, the cap 
sections can be disposed in close-fitting intermeshed and/or 
interdigitated relation one to the other for receiving a relatively narrow 
series loop with strand-to-strand braze or can be formed to a wider 
configuration for receiving the wider series loop with single-shot braze. 
Of course, different configurations of loops, as well as different 
thicknesses of loops can likewise be accommodated. 
To mechanically lock the two cap sections one to the other, potting resin 
is disposed within the cap sections and fills the openings in the tabs and 
opposite side walls. The potting resin in those openings forms locking 
pins which hold the cap sections captive to one another in the event of a 
bond failure. 
Additionally, the cap sections may be assembled prior to assembly over the 
loop or they may be assembled as a clamshell-type cap. Thus, the potting 
resin may be disposed in the two cap sections and the sections assembled 
together and subsequently pushed over the series loop. Alternatively, the 
cap sections may be closed about the loop, as in a clamshell 
configuration. The cap sections may be temporarily held together with 
spring clamps or large rubber bands while the potting resin cures. 
Alternatively, the cap may be tied in a closed condition with permanent 
banding tape serving to lock the cap on the loop. 
In a preferred embodiment according to the present invention, there is 
provided a cap for disposition on the series loop of a bar wound armature 
of an electrical system, comprising first and second substantially 
identical cap sections, each section having (i) first and second opposed 
generally parallel longitudinally extending side walls, (ii) an end wall 
extending generally transversely between the side walls adjacent one end 
of the section and (iii) a cover extending between the side walls and from 
the end wall along one side of the cap section leaving free the margins of 
the side and end walls along the opposite side of the cap section. Each 
end wall has first and second generally parallel segments offset one from 
the other in the longitudinal direction with the second segment being 
inset longitudinally from the first segment, each first end wall segment 
extending from the first side wall generally transversely toward the 
second side wall, each the second end wall segment extending from the 
second side wall generally transversely toward the first side wall, the 
first and second segments having edges inset from the free margin of the 
end wall at a location therealong intermediate the side walls. The first 
and second sections are assembled to form the cap with (i) the first and 
second side walls of the first section lying generally parallel and 
side-by-side with the respective second and first side walls of the second 
section, (ii) the first and second end wall segments of the first section 
lying in side-by-side generally parallel relation with the respective 
second and first segments of the second section, and (iii) the covers of 
the first and second sections spaced one from the other on opposite sides 
of the cap whereby the covers, the side walls and the end walls define an 
enclosure open at the end thereof opposite the end walls for receiving the 
series loop of a bar wound armature. The inset edges of the first and 
second segments of the first section and the inset edges of the first and 
second segments of the second section enable the respective side walls of 
the first and second cap sections and the respective end wall segments 
thereof to intermesh and thereby form the cap. 
In a further preferred embodiment according to the present invention, there 
is provided a cap enclosure portion for disposition on the loop of a bar 
wound armature of an electrical system, comprising a cap section having 
(i) a pair of opposed generally parallel longitudinally extending side 
walls, (ii) an end wall extending generally transversely between the side 
walls adjacent one end of the section and (iii) a cover extending between 
the side walls and from the end wall along one side of the cap section 
leaving free the margins of the side and end walls along the opposite side 
of the cap section. The end wall has first and second generally parallel 
segments offset one from the other in the longitudinal direction with the 
second segment being inset longitudinally from the first segment, the 
first and second end wall segments each extending transversely from a 
respective side wall generally toward the opposite side wall. The first 
and second segments have edges inset from the free margin of the end wall 
and define an opening in the end wall and which opening opens through the 
margin of the end wall, the section further including a longitudinally 
extending tab spaced closely adjacent and substantially parallel to one of 
the side walls to define a slot therewith having a width at least equal to 
the width of the opposite side wall section. 
In a further preferred embodiment according to the present invention, there 
is provided a cap for disposition on the loop of a bar wound armature of 
an electrical system, comprising first and second substantially identical 
cap sections, each section having (i) a pair of opposed generally parallel 
longitudinally extending side walls, (ii) an end wall extending generally 
transversely between the side walls adjacent one end of the section and 
(iii) a cover extending between the side walls and from the end wall along 
one side of the cap section leaving free the margins of the side and end 
walls along the opposite side of the cap section. Each end wall has first 
and second generally parallel segments offset one from the other in the 
longitudinal direction with the second segment being inset longitudinally 
from the first segment, the first and second segments having edges 
defining a portion inset from the free margin of the end wall and disposed 
substantially medially of the end wall, the first and second sections 
being assembled to form the cap with (i) the side walls of the first 
section lying in generally parallel juxtaposition with the respective side 
walls of the second section, (ii) the first and second end wall segments 
of the first section lying in side-by-side generally parallel relation 
with the respective second and first segments of the second section, and 
(iii) the covers of the first and second sections lying in spaced 
opposition one to the other whereby the covers, the side walls and the end 
walls define an enclosure open at the end thereof opposite the end walls 
for receiving the loop of the bar wound armature, the inset portions of 
the first and second cap sections enabling offset intermeshing of the 
sections in a transverse direction when assembled to form a cap. 
Accordingly, it is a primary object of the present invention to provide a 
novel and improved cap for enclosing series loops of an armature in an 
electrical system wherein the cap is formed of two identical sections from 
a single mold and which cap sections can be readily and easily assembled 
in intermeshed transversely offset and longitudinally aligned relation to 
one another to define a cap having a selected width whereby series loops 
of different sizes, particularly widths may be accommodated. 
These and further objects and advantages of the present invention will 
become more apparent upon reference to the following specification, 
appended claims and drawings.

DETAILED DESCRIPTION OF THE DRAWING FIGURES 
Reference will now be made in detail to a present preferred embodiment of 
the invention, an example of which is illustrated in the accompanying 
drawings. 
Referring now to the drawings, particularly to FIG. 1, there is illustrated 
a series loop, generally designated 10, with a strand-to-strand brazed 
connection, and a cap, generally designated 12, for overlying and 
receiving the end of the series loop connection 10. Cap 12 is formed of 
two identical or homomorphic cap sections 14 assembled together to form 
essentially a five-sided enclosure having opposed spaced side walls, an 
end wall, a pair of covers spaced one from the other and an opening 
opposite the end wall for receiving the series loop connection. 
Referring to drawing FIGS. 3 and 4, the cap section 14 includes a pair of 
spaced side walls, e.g., first and second side walls 16 and 18, 
respectively, an end wall 20 interconnecting said side walls 16 and 18 at 
one end of cap section 14 and a cover 22 extending between side walls 16 
and 18 and from end wall 20, leaving free, as illustrated in FIG. 4, the 
margins of the side and end walls along the side of the cap section 
opposite the cover 22 (the upper side as illustrated). 
End wall 20 is comprised of a pair of end wall segments, e.g., first and 
second end wall segments 24 and 26, respectively. End wall segments 24 and 
26 extend generally parallel one to the other but are offset in a 
longitudinal direction. (For purposes of this description, the 
longitudinal direction in FIG. 1 lies in the directions of the arrow A, 
whereas the transverse direction extends in the directions of the arrow B, 
i.e., from one side wall to another). Longitudinally offset end wall 
segments 24 and 26 have edges 28 and 30, respectively, which extend from 
the free margins of the end wall segments inwardly toward the opposite 
cover 22. Edges 28 and 30 are also inclined toward one another to define 
an inset portion or opening 32 at least equal to one-half of the depth of 
the end wall 20, as illustrated in FIG. 4. Thus, edges 28 and 30 lie 
longitudinally offset one from the other. Additionally, edges 28 and 30 
and inset portion 32 defined thereby lie substantially medially of the 
length of end wall 20, for reasons which will become apparent from the 
ensuing description. It will be appreciated, however, that inset portions 
defined by inclined edges such as edges 28 and 30 may be located at spaced 
locations along end wall 20, rather than medially as illustrated, provided 
such edges can intermesh one with the other when the cap sections are 
assembled, as set forth in the ensuing description. The opposite end of 
cap section 14 is defined by the free end edges of side walls 16 and cover 
22. 
As best illustrated in FIGS. 3, 4 and 5, a longitudinally extending tab 34 
is disposed adjacent first side wall 16 in generally parallel relation 
therewith and extends from a location adjacent end wall 20 to a location 
intermediate the longitudinal extent of the cap section. Tab 34 thus 
defines a slot 36 with side wall portion 16 in juxtaposition therewith for 
receiving, in assembly, a portion of the opposite second side wall 18. Tab 
34 extends from the cover 22 and is preferably of the same depth as side 
wall 16. Tab 34 may, however, be secured to side wall 16 adjacent cover 22 
and does not necessarily require securement to cover 22. Along the 
opposite side wall 18, there is provided a rib 38. Rib 38 is disposed at a 
longitudinal location along side wall 18 beyond the tab 34. 
To assist in securing cap sections 14 one to the other in assembly, an 
opening 40 is formed through tab 34. A similar opening 42 is formed 
through the second side wall 18 adjacent its distal end. It will be 
appreciated that, with the foregoing construction of the cap sections, 
each cap section may be formed of a dielectric material, for example, a 
resin, formed in a single mold whereby an assembly of a pair of such 
homomorphic or identical cap sections may form the cap for receiving the 
series loop connection. 
To assemble a pair of cap sections 14 to form cap 12, the side walls and 
end wall segments are respectively intermeshed whereby the cap sections, 
in final assembly, are transversely offset one from the other a distance 
corresponding substantially to the width of a side wall. The cap sections 
14 are, however, longitudinally aligned one with the other. This 
longitudinal offset can be seen in FIG. 1, wherein the first side wall 16 
of a first cap section and a first end wall segment 24 is illustrated, 
whereas the cover 22, and first end wall segment 24 and first side wall 16 
of a second cap section are illustrated. For convenience in describing the 
assembly, the letter notations (i) and (ii) are used to denote the various 
parts of the first and second cap sections, respectively, in assembly. 
Thus, when identical cap sections 14 are intermeshed one with the other, 
side walls 16(i) and 18(i) of cap section 14(i) lie in generally parallel 
juxtaposition with the respective side walls 18(ii) and 16(ii), 
respectively, of the second cap section 14(ii). First side wall 16(i) of 
the first cap section 14(i) lies outwardly of side wall 18(ii) of second 
cap section 14(ii). Conversely, the first side wall 16(ii) of second cap 
section 14(ii) lies outwardly of second wall 18(i) of first cap section 
14(i). Note also that a portion of side wall 18(ii) of second cap section 
14(ii) lies between tab 34(i) and side wall 16(i) of first cap section 
14(i) and inwardly of rib 38(ii) of second cap section 14(ii). Similarly, 
a portion of side wall 18(i) of first cap section 14(i) lies between tab 
34(ii) and side wall 16(ii) of second cap section 14(ii). In each case, 
rib 38 lies between the end of tab 34 and the open end of the enclosure 
formed thereby. 
A review of FIG. 2 also reveals that first and second end wall segments 
24(i) and 26(i) of the first cap section 14(i) lie in side-by-side 
parallel relation with respective second and first end wall segments 
26(ii) and 24(ii) of second cap section 14(ii). It will also be 
appreciated from a review of FIG. 7b that the inset edges of the end wall 
segments of each cap section respectively intermesh with the inset edges 
of the end wall segments of the other second cap section. Thus, the cap 
sections are transversely offset one from the other, as illustrated in 
FIG. 1, but are longitudinally aligned one with the other. The inset edges 
28 and 30 accommodate the longitudinal alignment and transverse offset. It 
will also be appreciated from a review of FIGS. 7a and 7b that the cap 
sections may be assembled to selected widths, depending upon the degree to 
which the sections are intermeshed. 
To lock the cap sections in assembled relation one with the other, a 
potting resin may be disposed in the cap sections in the openings 40 and 
42. The potting resin thus forms locking pins in assembly when the resin 
is cured. 
It will be appreciated that the cap sections may be assembled directly onto 
the series loop connections. Thus, the cap sections may be disposed on 
opposite sides of a series loop and pressed toward one another, with the 
side walls and end wall segments intermeshing with one another, 
respectively, as previously described. Alternatively, the cap sections may 
be disposed about the end loops in a clamshell-type manner. Of course, 
additional securing means may be desirable and may comprise, e.g., banding 
tapes disposed about the cap sections when assembled. 
Referring to FIGS. 8 and 9, there is illustrated a series loop with a 
single-shot braze connection. This is a different form of series loop 
connection than the strand-to-strand braze connection illustrated in FIGS. 
1 and 2. It will be appreciated that the single-shot braze connection 
requires a greater width than the strand-to-strand braze connection of 
FIGS. 1 and 2. This is clearly illustrated upon a comparison of FIGS. 9 
and 10, which further illustrate the formation of a cap in selected widths 
to accommodate series loop connections of different widths. 
While the invention has been described in connection with what is presently 
considered to be the most practical and preferred embodiment, it is to be 
understood that the invention is not to be limited to the disclosed 
embodiment, but on the contrary, is intended to cover various 
modifications and equivalent arrangements included within the spirit and 
scope of the appended claims.