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Патент USA US2107821

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Feb. 8, 1938.
Filed Oct. 1_8, 1934
JosçphEZF’a/rrel l ,
Patented Feb. 8, 1938
Joseph E. Farrell, Washington, D. C., assigner
to Automotive Devices Corporation, Washing
ton, D. C., a corporation of Delaware
Application October _18, 1934, Serial No. 748,959
11 Claims. (Cl. 200-89)
This invention relates to a device for normally
maintaining an electrical service line circuit
closed. but which automatically functions upon
the existence of unusual conditions in the line,
5 such as surges resulting from a short or over
load, to automatically open the circuit for the
purpose of protecting electrical apparatus in
cluded therein.
A general object of the invention is to provide
10 a novel device intended to obviate the use of a
fuse of the type including a .strip of metallic
one of its essential elements a construction where
in a barrier of insulation is automatically and
positively interposed between the switch _con
tacts when the device is called upon to function
to open the line thereby eliminating an air gap
between the switch contacts and keeping them
adequately separated and insulated until con
ditions are such as properly to permit 'of restor
ing the circuit.
A further and distinctive object of the inven-I
tion is to provide a novel arrangement whereby
after the device has once functioned to open the
line, the barrier of insulation will not only be
generally unsatisfactory for numerous reasons. ' maintained or kept between the separated switch
In the first place when a device of this type has contacts but it will be impossible to manually 15
reset the switch until after the unusual condition
once functioned it must be discarded and re
placed by a new one. Consequently, this causes in the line has been remedied. That is to say,
alloy which melts or breaks upon the occurrence
of the unusual condition in the line and which is
~ not only a waste of the article itself but fre
quently requires much time and labor to locate
where many circuits are involved, and also
20 causes inconvenience and delay due to loss of
the circuit while the replacement is made.
Therefore, the present invention contemplates
an improved device of the electromagnetic
switch type which may be used indefinitely after
2 Ol it is once installed by merely manually resetting
the switch portion thereof to restore the circuit
after it has been automatically opened to safe
guardV the line.
While electro-magnetic devices of this general
30 type have heretofore been used, nevertheless
many of them are open to the objection that
they do not reliably function and are particu
larly objectionable because after they have func
tioned to open the line circuit, the switch ter
minals are left unguarded or unprotected so that
in the event that a subsequent unusual surge oc
curs in the line, an arc is produced between the
exposed switch terminals due to the fact that
they are only separated by an air gap. Also,
the movement of the resetting means in an at
tempt to reclose the switch will be idle so long as
the unusual condition persists. In that connec
tion, the invention contemplates as a part of the 20
resetting means a pair of insulated movably re
lated elements, one of which carries a manual
resetting handle while the other carries the in
sulation barrier for separating the contacts, and
as long as the unusual condition exists in the 25
line, these two members will be disconnected so
that the manually shiftable element may be
moved independently of the insulation barrier or
cut-olf, and only when the unusual condition
ceases to exist in the line will it be possible for 30
these two members to be automatically coupled
«or connected to effect the resetting and reclosing
of the switch.
kA further object of the invention is to provide
a simple, compact and reliable construction which 35
lendsl itself to an embodiment that facilitates
manufacture and assembly and which because
of its simplicity‘ and substantial construction will
function indefinitely without being removed or
disconnected from the line circuit.
With the above and other objects in view
many devices heretofore used have been open
to the objection that the manual resetting means
may be operated to bring the switch contacts which will more readily appear as the nature
intoengaging relation while the short or other , of the invention is better understood, the in
unusual condition still exists in the line with the vention consists in the novel features ci’ con
result that if it is attempted to manually hold struction, combination and arrangement of parts',
the switch in its closed position in an eifort to hereinafter more fully described, illustrated in
reset it while still subjected -to unusually high the accompanying drawing and deñned in the
voltage, arcing will also occur which will not only appended claims.
A preferred and practical embodiment _of the 50
destroy the switch contacts but in some cases
produce an arc of such high intensity that it will invention is shown in the accompanying draw
flash beyond the limits of the device and burn 0r ing, in which:--, Figure l is a side elevation of the improved
otherwise injure the hand of the party endeavor
ing to reset the switch.
' ’
Accordingly, the invention contemplates as
Figure 2 is a top plan view thereof.
Figure 3 is a vertical cross-sectional view
i taken on the line 2--3 of Figure 2.
Figure 4 is a horizontal sectional view taken
on the line 4_4 of Figure 3.
Figure 5 is a detail vertical section similar
to Figure 3 but showing the switch in open posi
Figure 6 is a detail vertical sectional view taken
on the line 6_8 of Figure 3.
Figure '1 is a detail’perspective view of the
metallic parts of the switch.
Figure 8 is a detail perspective view of the
amature member.
According to the embodiment of the inven
tion shown in the drawing, the same essentially
includes in its organization a supporting as
upwardly extending rear wall Il. This forma
tion provides in eifect a socket for receiving an
insulating supporting plate I6.
This plate is
provided with a slot I1 and having its end op
posite the socket terminating at and abutting
against one of the sides of the switch contact 9
as will be apparent from Figures 3 _and 5. The
upper surface of the insulation plate I8 is there
fore ñush with the upper surface of the contact
9 for the purpose which will presently appear.
Mounted on the upper surface of the support
ing plate Il are a pair of nested telescopically
related insulating members which are intended to
be connected vor disconnected automatically as
conditions require. These insulating members
are respectively a sliding contact separator and
*barrier block G and a reclosing or resetting yoke
ing carried thereby and designated generally as H. Both are normally restrained spring ac
B, the latter being fitted with a cover C which tuated members, automatically released.' and
20 is held to the housing by a flanged ring or equiv
manually reset.
' aient means D.
The barrier block G is formed with a body Il
Referring first to the supporting assembly A having at its forward end an insulating toe Il
it may be pointed out that the same essentially which constitutes the barrier adapted to be in
includes a pair of main circuit terminals I and terposed‘between the switch contacts 2 and Il
25 >2 which may be respectively in the form of a
when the circuit is open. The rear face of the 25
block is provided with a seat for receiving a coil
metallic shell and a center contact 2. The metal
lic shell I or its equivalent preferably houses an spring 2l whose opposite end engages with the
electromagnet 3, suitably insulated therefrom, wall I5 of the switch frame. The body of the
sembly designated generally as A, a switch hous
and having at one end thereof an insulation
30 plate or washer 4 while the opposite end abuts
block is also provided with a central recess or
against one side of the cupped or recessed switch
thereof and adapted to receive a detent or latch
housing or base B. The center contact 2 is pref
22 which is normally urged upwardly by a spring
23 confined between the underside of the head
erably in the form of a bolt whose shank 2l
provides a core for the magnet and whose head
35 2b is intended to ilt within a recess 5 at the base
cavity 2I having an opening in the bottom 30
of the latch and the base of the cavity while the
shank of the latch projects through the opening 35
of the housing so that when a rivet, or its equiv
in the bottom of the recess or cavity and ex- .
alent, 2c is fitted to the opposite end, the _said
center contact will hold the parts I, 2, l and B in
tends through the slot I1 to receive a nut 2l.
This nut is slidably interlocked with the sides of
assembled relation. One end of the coil of the
magnet 3 is in contact with the combined center
contact land core member 2 as indicated at :c
While the other end of the wire forming the
a slot 2l in an armature member 2l. The latter
is pivoted as at 21 to the ears Il of the switch 40
magnet coil is led upwardly through the bottom
of the switch housing B to a suitable conductor
45 member 8 positioned and exposed at the face of
the shoulder 1 within the switch housing. As
shown in Figures 3 and 5, a portion of the metal
shell constituting the circuit terminal I may be
extended upwardly as indicated at 8 and bent
50 over or otherwise secured as indicated at l* in
frame and the spring-22 ofthe latch urges the
armature member away from the head 2"- of
the combined center contact and-magnet core
2-2‘, and also urges the latch toward socket
2l of member H.45
The sliding barrier block G is nested within
the resetting yoke H which includes an insula
tion body 2l having a handle 2l adapted to pro
ject through a slot 2| in the cover C and is -also
provided with _the side walls 22 whose bottom
edges rest on the plate Il to surround and house
the shoulder 1. The end 8* of the screw shell
may, of itself, constitute one of the switch con ' the sliding switch block G. The body 29 is also
tacts, but in the assembly shown, it is preferred provided with a rear wall 32 having an opening
for permitting the passage therethrough of the
to have the said end Il engage with a station
55 ary switch contact 9 intended to cooperate with
a movable switch contact III carried by a spring
switch lever II which is preferably formed as
a part of a metallic switch frame designated gen
erally as F.
The switch, of which the parts 9, IU and I I are
a part, is designated generally as S, and these
parts, together with their supports and control
members are preferably arranged and assembled
as a unit which may be fitted into the hollow or
65 recessed portion of the switch housing B, above
the shoulder 1, so as to rest on the latter when
the parts are assembled, and be held in place by
the cover C.
Referring further to the switch unit S it will
70 be observed that the metal switch frame F which
includes the yieldable spring switch lever II also
comprises a body portion having a rounded rear
wall I2 integral with the arms of the switch le
ver and is also provided with a bottom wall Il
75 having the depending perforated ears Il and the
spring 2l, the said wall also constituting an abut
ment for one end of the coil spring 24 confined
between the wall 23 and the wall I5 of the switch
lever frame. The spring 34 is of larger diameter
than the spring 20 so that the latter is nested
within the former. The inside face of the upper 60
wall portion of the body 29 is provided with the
keeper recess or socket 2s intended to receive
the detent or head 22 of the armature controlled
latch. When the detent or latch head 22 is en
gaged in the socket 2l as shown in Figure 3, it 65
will be apparent that the members G and H will
be interlocked and may be moved together. On
the other hand, when the amature 26 is at
tracted to the head 2b of the combined core and
center contact 2-2‘ as shown in Figure 5, the 70
parts G and H will be free to move independ
ently of each other.
For the purpose of holding the members G and
H in their retracted podtion, when interlocked
by the detent 22, the forward end of the upper
wall of the body 29 of the resetting yoke is pro
ing of the parts G and H will be held poised in
vided with a shoulder Il for engagingwith the
their reset position.
upwardly extending bail shaped strap II* on the
switch lever as, will be observed from Figure 3.
Thus, when the device is in use and normal oon
ditions >exist in the line, it will be apparent that
lthe parts assume the position shown in Figure 3
wherein the part II* of the switch lever is en
gaged with the shoulder 2l of the resetting yoke.
Likewise, the members _G and H will be inter
locked by the detent 22 and the armature 20 will
be urged upwardly by the spring 22.
Upon the occurrence of a short or overload in
the circuit including the present device, the mag
net M will be activated and will attract the arma
ture 28 against the tension oi.' the spring 22. This
movement o! the amature will pull the latch or
detent 22 downwardly and> release the barrier
block G from its interlocking engagement with
20 the manually controlled resetting member H and
the spring 2li will push the barrier block G for
wardly so that the insulating toe Il will be thrust
between the switch contacts 8 and It. The spring
switch lever II is normally biased to the closed
25 position so that contacts 9 and Ill are normally
engaged. However, when the short or overload
occurs the block G may move forward, after re
lease from the member H by the withdrawal of
the detent 22, due to the fact that the detent 22
30 at its shank portion can freely slide in the slot 25
of the armature member. When the insulating
- ban'ier or toe I9 raises or lifts the spring switch
contact I0, it also elevates the upper arched por
tion of the strip I Il so as to remove the same from
13 Gl obstructing relation to the shoulder 25 on the re
setting yoke H. Therefore, when I Il is moved out
of the path of l5, the spring 3l can push the mem
ber H to the position shown in Figure 5. In this
figure, the parts G and H are in the same rela
40 tive position that they are in Figure 3 except that
the insulating barrier or toe I0 of member G is
interposed between contacts 9 and Ill and no cur
rent can pass between these contacts.
I! the undesirable condition persists in the line,
45 it will be apparent that the armature 26 will be
pulled to its downward position each time the
handle 30 is moved from the full line position in
Figure 5 to the dotted line position because the
circuit is re-closed between contacts 9 and I0.
50 When this condition exists, it will be apparent
that the resetting yoke H is disengaged from the
slidable block G so that in event the handle 30 is.
moved from the full line position to the dotted line
position shown in Figure 5, its movement will be
55 idle so far as resetting is concerned and the spring
Il will push the member G back to its former po
sition between contacts 9 and III, and which is
the “off” position of the switch.
On the other hand, if the short, or overload in
the line is only of temporary duration and the ar
mature 28 is released, it will be apparent that the
spring 23 will return the armature to its normal
position and consequently the detent 22 will move
upwardly into the socket 28. Thus, the parts G
85 and H will be interconnected again and by moving
the handle 20 from the full line position in Fig
ure 5 to the dotted line position, it will be appar
ent that the insulating barrier I9 may be with
drawn from between the contacts 9 and I0 and the
70 spring switch lever II will move downwardly to
re-establish the circuit. Likewise, when the reset
ting yoke -H is retracted, the upper portion of the
strap I I* will again become seated in the shoulder
25 so that the entire actuating assembly consist
Upon the subsequent occurrence o! a short or
overload in the line, the latch or detent 22 will be
pulled/downwardly and the spring 20 will thrust
the block G forwardly to separate the contacts 9
and III and the circuit will be open. Resetting
may be eßecœd again as previously described, and
these operations may be repeated indeiinitely if
From; the foregoing it will be apparent that a
distinctive feature of the invention resides in pro
viding means whereby the switch contacts will be
positively separated and blocked by a. barrier of
insulation immediately upon the opening of the
circuit. As long as the undesirable condition per
sists in the line. this insulation barrier will remain
in place and manipulation of the resetting means
cannot permanently remove the barrier from its
obstructing relation to the switch contacts. On 20
the other hand, if the unusual condition auto
matically expires as quickly as it automatically oc
curred, then, the device may be reset manually for
further use. As long as the insulation barrier re
mains between the contacts, subsequent surges o!
high voltage current will produce no harmful re
sult on the apparatus or on the attendant, thereby
increasing the safety factor inherent in the device
and substantially eliminating all hazards incident
to the circuit being closed while the short per v30
sists inthe line. _
Without further description it is thought that
the features and advantages of the invention will
be readily apparent to those skilled in the art, and
it will of course be understood that changes in the 35
form, proportion and minor details of construc
tion may be resorted to, without departing from
the spirit of the invention and scope of the ap
Y pended claims.
1. In an automatic device for protecting elec
tric service lines, a pair of switch contacts, one of
which is movable with reference to the other,
normally interlocked manual and automatic in
sulation means for controlling the movable con
tact, restraining means for said manual means
which in turn controls said automatic means while
both are interlocked, an insulation barrier actu
ated by the automatic means to open and sepa
rate the contacts when the manual and auto
matic means are unlocked, and magnetic means
for unlocking the manual and automatic means .,
and rendering said manual means incapable of
being reset by the restraining means while ab
normal conditions exist in the line.
2. In an automatic device for protecting elec
trical service lines, a pair of normally engaged
switch contacts, separate spring urged manual
and automatic insulation elements for controlling
said contacts, means for normally interlocking
said manual and automatic elements, restraining
means effective while said elementsare inter
locked, means associated with said automatic ele
ment for separating and insulating said contacts,
and magnetic means for unlocking said manual
and automatic elements and rendering said re
straining means ineffective while abnormal condi
tions exist in the line, whereby the manual ele
ment can not be reset.
3'. In an automatic device for protecting elec
trical service lines, switch contacts one of which
is normally spring biased to engage the other,
and means for controlling said ilrst named con
tact, said means including a slidable insulation
barrier and-a manually operated reelosing mem
_ - ber, spring means for urging said members in one
¿ direction, means for normally interlocking said
members, means for restraining said members
while interlocked against the force of said spring
Cà means, electro-magnetically operated means for
movement whereby the insulation member in
i'or engaging with said movable contact, means
for urging said control members in one direction,
a latch carried by the control member having the
insulating toe and adapted to engage with s
socket in the member having the shoulder, a
passing between the switch contacts rendersßaid
spring for normally urging the latch into the
restraining means ineiiective to prevent resetting
of the reclosing member while it is disconnected.
socket, an armature member in operatlve'rela
tion to the magnet, and means for slidabiy con
necting the latch and the amature.
9. In a device of the class described, a pair oi
switch contacts, one o! which is movable with
reference to the other, an electromagnet in cir
cuit with one of said contacts, a pair oi’ shiftable
telescopically related control members, one of
releasing said members Vfor relative independent
from the insulation member.
4. In an automatic device ior protecting elec
‘ trical service lines, switch contacts one oi' which
is normally spring biased to engage the other,
and means for controlling said ?rst named con
tact, said means including a switch opening in
sulation member and a manually operated re
closing member, means for normally interlocking
said members, means for restraining said mem
bers while intcriocked, and electro-magnetically
operated means for releasing said members from
said restraining means thereby to open the switch
contacts and simultaneously render the reclosing
member inoperative while the electromagnetic
means is capable of being actuated by a persist
ing overload in the line.
5. An automatic switch for protecting electric
service lines including a pair of switch contacts,
an electro-magnet in circuit with one switch
to be projected between said switch contacts, and
the other oi which is provided with a shoulder
contact, a pair of superimposed nested and slid
ably related spring actuated insulation members,
locking means for normally restraining the said
members, means attracted by said electro-mag
which is provided with an insulating toe adapted
to be projected between saidswitch contacts, and
the other oi which is provided with a shoulder
and a socket, a latch for engaging with a socket 20
in the member having the shoulder, a spring for
normally urging the latch into the socket, an
armature member having a slot, and a member
carried by the latch and having a slidable guid
ing engagement in the slot oi the armature
10. In a device of the lclass described, a pair
of switch contacts, one of which is stationary
and the other of which is movable, an electro
magnet in circuit with one of said contacts, said 30
movable contact including a spring arm having
a contact portion normally adapted to engage
with the stationary contact, restraining means
net upon the occurrence of an overload in the
i line for releasing said locking means whereby
one of the members may slide to separate the
on the movable contact, a pair oi' shiitable con
trol members, a shoulder on one of said members,
switch contacts while the other is set free to
slide idle with respect to the first mentioned
the contacts, an insulating member carried by
one oi.' said control members and- adapted to be
member as long as said means may be attracted
slidabiy proiectedlbetween the iixed and movable
by the electro-magnet.
switch contacts to separate the same and elevate 40
6. In a device of the class described, a’pair of
switch contacts, one of which is movable with
reference to the other, an electromagnet in cir
cuit with one of said contacts, shiitable super
imposed control members oi insulation material
for said movable contact, springs for urging said
members in one direction, an armature in oper
ative relation to the electromagnet, spring latch
means connected with said armature for coupling
and uncoupling said control members, and coop
erating means on the movable contact and one
of the control members for maintaining the same
in normal position While connected by the latch.
7. In a device of the class described, a pair oi
switch contacts, one of' which is movable with
reference to the other, an electromagnet in cir
cuit im‘th one of said contacts, shiftable control
members for said movable contact, one of said
members having an insulating toe adapted to be
projected between said contacts, means for urg
ing both of said control members in one direc
tion, a spring latch carried by said member hav
ing the insulating toe, a socket in the other con
trol member for receiving said latch, an arma
ture in operative relation to the electromagnet,
and means for slidabiy connecting said latch
with the armature.
8. In a device of the class described, a pair of
switch contacts, one of which is movable with
reference to the other, an electromagnet in cir
cuit with one oi said contacts, a pair of shiitable
telescopically related control members, one of
which is provided with an insulating toe adapted
means for urging said control members toward
the movable contact whereby the restraining
means thereof will be lii’ted clear oi the shoulder
of the other ot said control members, latch means
for interconnecting said control members, and
an armature member slidabiy interlocked with
said latch means.
l1. In a device oi' the class described, a sta
tionary switch contact, a movable switch con
tact, said movable switch contact being normally
engaged with the fixed contact, an electromag
net in circuit with one oi said contacts, a pair oi
shiitably mounted control members, latch means
ior releasably interlocking said members, means
i'or urging said control members in one direc
tion, insulation carried by one of said members 55
adapted to be projected between said ilxed and
movable switch contacts to open the switch, a
handle on one of said control members, restrain
ing means on the movable switch member for
engaging the control member having the handle, 60
an armature operatively related to the electro
magnet and adapted to actuate said latch means
upon the occurrence of an overload in the line
circuit thereby to disconnect said control mem-v
bers and permit the insulation toe to be projected 65
between said ?xed and movable switch contacts
and to displace the restraining means of the mov
able contact out oi the path oi' the control mem
ber having a handle whereby manipulation oi
the latter will render the control members in 70
eiIective as long as the magnet attracts the ar
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