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Патент USA US2106109

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Jan. 18, 1938.
P, PRENDERGAST
2,106,109
FUSE PLUG
Filed June 4; 1936
INVENTOR
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2,106,109
Patented Jan. 18, 1938
UNITED STATES PATENT OFFICE
2,106,109
FUSE PLUG
Pierce Prendergast, Pittsburgh, Pa.
Application June 4, 1936, Serial N0. 83,462
9 Claims. (Cl. 200--125)
My invention relates in general to fuse plugs
and is particularly applicable‘ to a multiple-fuse
the customary sockets so that it is unnecessary
to change the wiring ?xtures. The plug as a
plug so arranged that a portion of the plug may
whole need be rep-laced only after all of the fuse
elements have been blown.
In the drawing, I have illustrated a present
preferred embodiment of my invention and there
in corresponding and like parts are designated
by like reference numerals.
be turned so that a new section of the fuse ele
5 ment may be engaged after one fuse section has
been melted out by a short circuit or by
over“
load on the line, thereby eliminating the neces
sity of removing the plug and inserting a new
one in order to make the circuit operative.
11
i.)
Figure 1 is a side elevation of the fuse plug
By my invention, I provide a fuse plug which
may be readily placed in the circuit and which
complete;
may be conveniently and quickly manipulated
of Figure 1;
to place a new section of the fuse element in the
circuit as the occasion arises.
Heretofore, attempts have been made to pro~
vide a suitable multiple-fuse plug, but, insofar as
I am aware no one has been successful.
One of
the serious draw-backs has been the tendency to
a‘ fuse all of the elements at once, which draw-back
J I have overcome. A fuse plug made according
to my invention is perfectly reliable, safe, and
positive in operation and may be produced in an
economical manner. The plug is so insulated
that there will be no possibility of a short circuit
[O CH occurring therein or of more than one section
of the fuse element blowing out at the same time.
The fuse plug is provided with a rotatable cap
member and secured therein is a fusible member
having a plurality of arms, any one of which
3 O may be connected into the circuit so that in the
event of one of said arms blowing, another arm
may be moved into circuit closing position. This
operation may be repeated as often as is neces
sary or until all the arms in succession have been
blown.
By inspection through the cap member,
one can readily determine which arm of the fuse
element has blown. The cap is provided with
means to prevent it turning in any ‘out the proper
direction, which means also assure that the ele
ments are in the correct operative position which
can be determined audibly and by touch. Post--~
tive contact between the end of the plug and the
socket in which it is placed is also provided for.
Provision is also made for preventing arcing
~5
.g. when a fuse blows, which arcing is particularly
liable to occur when the fuse is employed for
protecting circuits carrying currents of the order
of twenty amperes and upwards. The fuse made
according to my invention provides a combustion
chamber of such size that the pressure within the
chamber during combustion is insuiiicient to rup~
ture the fuse plug body.
My fuse plug, although capable of repeated
use, because of its multiple character need be no
larger in size than the ordinary fuse plug of com
mercial use, and may be manufactured at a low
cost, so that a fuse plug having the life of eight
ordinary plugs will cost about the same as the
single fuse plug now in common use. The fuse
to plug may be utilized in the customary way and in
10
Figure 2 is a cross-section on the line II-—II
Figure 3 is a plan View of the plug with the
rotatable cap removed;
Figure 4 is a bottom plan view of the rotatable
Cap;
Figure 5 is a cross-section on the line V—-V of
Figure 4;
Figure 6 is a plan view of the multiplemfuse ele
'20
ment before it is inserted in the cap;
Figure 'l is a plan view of the indicating mem
her; and
Figure 8 is a view in perspective of the sealing
member.
In the drawing, there is shown a body member
2 and a cap member or fuse carrier 3, both of
which are made from non-conducting material,
such as porcelain, ?bre, synthetic resin, or the
like. Preferably, the cap member is transparent.
The body member 2 includes at one end a re
duced portion 4, to which is applied a threaded
metallic sleeve 5 for screwing into the ordinary
Edison socket, and at the other end a cup'shaped
portion 6, in which is a depression or recess ‘l.
The threaded sleeve or shell 5 has a plurality
of arms or extensions 3, which pass through open
ings 9 into the recess 1 where they are secured
to the arcuate contact member it positioned in
the recess. This contact member It is formed
from resilient metal and has an upwardly turned 40
end H, which engages in turn the ends or arms
of the metal fusible element later to be described.
For ease in assembling there is formed in the
reduced portion 4, the grooves l2, one for each
arm ii.
The grooves l2 connect with the open
ings 9.
Inside the recess 1 is a centrally located boss
23 and extending axially through this boss and
through thebody member or insertible portion 2 is
a bore M, through which slidably extends a
metal pin or rod 15. To the lower end of this
rod, a U-shaped contact member 16 of resilient
metal is secured and between the enlarged head
H of the other end of rod l5 and the top of boss
l3, a spring i8 is positioned. Rod [5 is of such
length that when the plug is assembled the spring
I8 is compressed to a slight extent so that posi
tive contact between the head l1 and the fuse
element is maintained. One arm of the U~shaped 60
2
2,106,109
contact member 16 is received in a depression 19
in the lower or inner end of body member 2.
The cap member 3 formed preferably of glass
or other transparent insulating material by mold
ing or casting has a depression, well, or cavity
20, which extends into the cap from which cavity,
radial notches or grooves 25 extend, in which the
arms of the fuse elements are received. The
radial notches 2! are separated from one another
by partitions 22, which extend somewhat beyond
the end or lower edge of the outside wall 23 of
the cap member, so that between each pair of
partitions there is along the lower edge of the
wall depressed portions or recesses 24. t will be
observed that the edges 22a of the partitions 22
adjacent the recesses 24 are rounded so that the
end H of contact member EU will ride smoothly
out of the recesses 24 between the partitions.
The edges of the partitions adjacent the other
20 side of the recesses 2d are substantially vertical.
By this arrangement, the cap member may be
Since the notches 2| are closed at their outer
ends, but not gas tight, by projections 31 gas
chambers or combustion chambers are formed
wherein the gases generated by the blowing fuses
may expand without developing enough pres
sure to disrupt the fuse plug, and wherein any
resulting ?ame is con?ned. The assembly is not
gas tight, so that the gases may be dispersed into
the surrounding atmosphere without any harm
ful result.
The signal member or indicator 38, Figure '7,
10
has a hub portion 39 and radial arms 40 extend
ing therefrom. The member is made from paper
and the side which faces the top of the cap mem
her 3 is colored red and has a number thereon 15
denoting the ampere capacity of the fuse. The
member is of such size that it fits snugly into
cavity 20 of cap member 2 and the radial arms 40
thereof extend into the notches 2| of the cap
member. When the fuse in the same notch as 20
the corresponding arm of the signal member is
rotated in one direction only, for example, clock
blown, the radial arm is discolored, thus showing
wise as shown.
which fuse arm has blown out. It is also pos
sible to color the side of the fuse element which is
visible from the top of the plug so that the burned 25
arm will show up clearly, in which case the indi
cator 33 could be omitted.
The cap member is assembled by placing a sig
Furthermore, the end ll of con~
tact member l0 when it drops into the depressed
25 portion 24 makes an audible click and positive
contact with an arm of the fusible element.
A ridge or ?ange
extends circiunferentially
from the outside of the cap member at a con
venient location between the top and bottom
30 thereof. In the top or outside of the cap mem
ber 3, a depression 2s is provided, the shape of
which depends on the Fire Underwriters’ re
quirements. The outside of the cap member be
tween the ridge 25 and the top or outside of the
35 cap member is serrated, so that the member may
be gripped for turning,
The fuse element 2'1", see Figure 6, is formed in
the shape of a rimless wheel and has a. hub por
tion 28 having radial elements 29, extending
40 therefrom.
These elements have a hub contact
ing portion 30, blow-out reduced area portions 3:‘
and contact portions 32, which are of greater
cross-sectional area than the blow-out portions.
The contact portions 32 are preferably necked as
45 shown at 33, as an aid in assembling the fuse
plugs. It is, of course, understood that the con—
tact portion need not be necked to make satis
factory fuse and that the contact portion 32 may
be of uniform cross-section. The fuse is of such
50 dimension that the ends or" the radial arms will
pass through the notches 2i
beyond
recess
24, and extend part way on the flange
The
outer ends of the arms are retained in position by
a washer 34 of non-conducting material, pref
55 erably ?bre, which makes close ?t with the out~
side of the cap member and rests against the
lower side of flange 25.
The sealing member
see Figure 8, consists
of a sleeve 36 from the sides of which radial projections 31 extend, so spaced and of a size to be
The
received
sleeve
in 36
theis notches
long enough
Si in to
theextend.
cap member
from the
bottom of the fuse cavity 2! in the cap member
to and part way along the boss i3. The radial
65 projections 37 are so arranged on the sleeve that
they close the outer ends of the notches 2i and
lie below the outer edges of the partitions 22.
The sealing member 35 is made from a non—con~
ducting material and preferably from one that
70 can be performed as by molding or casting. I
have found that rubber is satisfactory and so also
is bakelite and ?bre, but I do not wish to be con
?ned to the use of these materials. The sleeve 33
is closely ?tted to the ends of the partitions 2;‘.
75 so-that each notch 2i forms a chamber by itself.
nal member 38 inside the cavity 2!, colored side
uppermost. The fuse element 21 is then inserted 30
in the cap so that the hub portion is received
in the cavity and the radial extending arms are
received in the notches 2|, the ends of the arms
extending around the ledges 24 where they are
secured in position by means of the ?bre washer 35
34. The sealing member 35 is then placed in posi
tion in the cap. The cap member is next placed
over the body member, as illustrated in Figure 2,
and is rotatably secured thereto by an annular
ring 4!, which has a ?ange portion 42 to engage
the upper side of ridge 25. The ring is secured to
the body member, for example, by crimping a. por
tion of the ring into grooves or recesses 43 in the
body member.
While I have illustrated and described a pre
ferred embodiment of my invention, it will be un
derstood that the invention is not limited thereto
and that various changes in the shape, size, num
her, and arrangement of parts may be resorted to
without departing from the spirit of my invention
or the scope of the following claims.
I claim:
1. In a multiple-fuse plug, a body member, a
cap member rotatably carried on the body mem
ber, said cap member having an inverted well -
therein, the outer walls of which are provided
with radially extending recesses, a fuse member
having a hub portion located against the bottom
of the well, radial arms with reduced area por
tions connected to said hub and located in the 60
recesses and extending vertically to the top of
the recesses and being turned over the edge of the
well, and a hollow sleeve member ?tted in the well
having radial projections fitting into the said
radial recesses, the radial extensions of the fuse 65
member having a part of the vertical portion
thereof of reduced area.
2. In a multiple-fuse plug, a body member, a
cap member rotatably carried on the body mem
her, said cap member having an inverted well
therein, the outer walls of which are provided
with radially extending recesses, a fuse member
having a hub portion located against the bottom
of the well, radial arms with reduced area por
tions connected to said hub and located in the
3.
2,106,109
‘recesses and eidsending vertically to the top of
the recesses and being turned over the edge of the
well, and a hollow sleeve member ?tted in the well
in contact with the inner edge portions of the cap
member forming the recesses and having radial
projections ?tting into the said radial recesses,
the radial extensions of the fuse member having a
part of the vertical portion thereof of reduced
area.
10
3. In a multiple-fuse plug, a body member, a
cap member rotatably carried on the body mem
ber, said cap member having an inverted wall
therein, the outer walls of which are provided with
radially extending recesses, a fuse member having
15 a hub portion located against the bottom of the
well, radial arms with reduced area portions con
nected to said hub and located in the recesses and
extending vertically to the top of the. recesses and
being turned over the edge of the well, a hollow
20 sleeve member ?tted in the well having radial
projections ?tting into the said radial recesses,
the radial extensions of the fuse member having
a part of the vertical portion thereof of reduced
area, and a contact member passing through said
hollow sleeve and engaging the hub portion of
the fuse member.
4. In a multiple-fuse plug, a body member, a
cap member rotatably carried on the body mem
ber, said cap member having an inverted well
therein, the outer walls of which are provided
with radially extending recesses, a fuse member
having a hub portion located against the bottom
of the well, radial arms with reduced area por
tions connected to said hub and located in the
recesses and extending vertically to the top of
the recesses and being turned over the edge of the
well, and a cylindrical sleeve of insulating mate
rial ?tted into the well for closing communication
from one recess to another, the radial extensions
of the fuse member having a part thereof of re
duced area.
5. In a multiple-fuse plug, a body member, a
cap member rotatably carried on the body mem
ber, said cap member having an inverted well
therein, the outer walls of which are provided
with radially extending recesses, a fuse member
having a hub portion located against the bottom
of the well, radial arms with reduced area por~
tions connected to said hub and located in the re
51) cesses and extending vertically to the top of the
recesses and being turned over the edge of the
well, and a cylindrical sleeve of insulating mate
rial ?tted into the well for closing communication
from one recess to another, the radial extensions
of the fuse member having a part thereof of re
duced area, said cap member having a laterally
turned flange and a non-conducting washer on
said ?ange engaging the outer extremities of the
radial arms.
60
6. In a multiple fuse plug, a body member
having an axial bore therethrough, a threaded
screw contact on vthe body member, a resilient
contact movably extending through said bore,
a cap member rotatably mounted on the body
65 member and having a centrally located cavity
and radial notches extending from said cavity
in which is received a fuse element having a hub
portions of said radial elements may be suc
cessively electrically connected to the screw con
tact, and means whereby the sides and outer
ends of said radial notches may be closed so as
to form combustion chambers for the reduced
area portions of the fuse element.
7. In a multiple fuse plug, a body member
having an axial bore therethrough, a threaded
screw contact on the body member, a second
contact extending through said bore, a cap 10
member rotatably mounted on the body member
and having a central cavity and radial notches
extending therefrom in which is received a fuse
element having a hub portion which contacts the
bottom of the cavity and radial elements having 15
reduced area portions connected to the hub
portion, said hub portion contacting said second
contact, means whereby the outer portions of
said radial elements may be successively electri
cally connected to the screw contact, a cylindri 20
cal member located in said cavity for closing the
radial notches so as to form combustion cham
bers for the reduced area portions of the fuse
element, said member having radial projections
thereon which close the ends of the notches, said 7'1
closing member being made of non-conducting
material, and means whereby the outer extremi
ties of the radial elements may be secured in
position on the cap».
8. In a multiple fuse plug, a body member ‘
having contacts for engaging the contacts of a
receptacle, a cap member havingv a centrally
located cavity and radial notches extending
therefrom into the sides of the cap, a fuse ele
ment received in said cap member and having
a hub portion located against the bottom of the
cavity and radial arms having a reduced area
portion connected thereto extending into the.
notches, resilient means connecting the hub por
tion with one of the contacts of the receptacle, 1
resilient means for connecting the portions of
the radial arms distant from the ends thereof
and beyond the reduced area portions to the
other contact of the receptacle, said reduced area
portions being con?ned in separate combustion
chambers, and means mounted on the cap for
holding‘ the outer extremities of the arms against
movement.
9. In a multiple fuse plug, a body member
formed cup-shaped at one end, a cap member .
rotatably received in the cup-shaped portion and
having a central cavity with radial notches ex
tending therefrom, a contact member secured
in the base of said cup-shaped portion and hav
ing an outwardly turned resilient end portion,
a fuse element carried by said cap member and
having a hub portion located against the bot
tom of the cavity and radial elements having
reduced area portions connected to- the hub por
tion, the radial elements passing through the
notches and over depressions in the edge of the
cap member, said portions in the depressions be
ing successively engageable upon rotation of said
cap member with the outwardly turned portion
of said contact member, means closing the ends 65
and sides of said radial notches, said depressions
and contact member being arranged so that the
portion located against the bottom of the cavity
cap may be rotated in one direction only, and
and radial elements having reduced area por
means mounted on the cap to hold the extremi
70 tions connected to the hub portion and extending
into the notches, said hub portion contacting
said resilient contact, means whereby the outer
ties of the radial arms securely in position.
PIERCE PRENDERGAST.
70
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