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Патент USA US2411352

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NOV. 19, 1946.
G, c_ ARMSTRONG
2,411,352
CUTOUT
Filed May 23, .1944
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WITNESSES:
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INVENTOR
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George G Arms/rang.
ATTORN EY
Patented Nov. is, 1946
2,411,352
‘UNITED STATES PATENT OFFICE
2,411,352
CUTOUT
’ George C. Armstrong, Forest Hills, Pa., assignor to
Westinghouse Electric Corporation, East Pitts
burgh, Pa., a corporation of Pennsylvania
1
Application May 23, 1944, Serial No. 536,952
13 Claims. (Cl. 200-422)
2
My invention is related to that of my copencl
A substantially cylindrical part, denoted as a
ing application for Thermostatic overload relays,
whole by 4, is arranged centrally within the cup
Serial No. 517,307, ?led January '7, 1944, and con
shaped hollow of the support I and is ?rmly se
cured thereto so as to remain stationary when the
cutout is in operation. The part 4 consists of
glass, ceramic or other refractory material and
has an axial hollow extending over its entire
length, In the illustrated embodiment, the con
tact 3 is designed as a rivet sleeve for attaching
cerns electric current or temperature-responsive
protective devices such as electric cutouts for
overload protection of electric motors and other
electric apparatus.
It is an object of the invention to provide an
overload or temperature-responsive contactor
which, as to size and simplicity of design, is com 10 the part 4 to the insulating body l. The lower
parable with the known cutouts using a fusible
portion 5 of part 4 has a larger diameter than the
element as a current-interrupting means, but
upper portion 6.
which is not subject to the considerable ageing
A cylindrical sleeve member ‘I, preferably of
of such fusible devices and permits reclosing the
metal, surrounds the insulating part 4 and en
electric circuit upon the occurrence of overloads. 15 gages its lower portion 5 with a sliding ?t so as
Another object of my invention is to devise
to be rotatable about part 4. The member ‘I has
a thermally operated contactor of small size in
at least two notches in its upper edge. One of
which an extremely great holding or looking force
these notches, denoted by 8, has a relatively large
is exerted on the movable contact means during
peripheral length and serves for engaging a re
normal operating conditions of the contactor so
setting member to be described hereinafter. A
that it is not a?ected by vibrations and shock
second notch is engaged by a movable contact 9
forces.
with a sufficiently close ?t to prevent rotations of
A further object of my invention subsidiary to
the contact relative to member ‘I. The contact
those aforementioned is to provide a contactor,
9 has an annular portion journalled on the top
especially an overload responsive cutout, whose
face of the stationary part 4. A stationary con
overall dimensions are small enough to permit
tact It], which in the illustrated embodiment is
placing the control mechanism and the apper
formed by leaf springs, is mounted on an interior
taining contact means within an enclosure hav
peripheral ledge ll of the insulating body i by
ing the shape and size of ordinary fuse plugs so
means of a screw I2 which forms also a con
as to be applicable in sockets of the type cus
duotive connection between the stationary con
tomary for receiving such plugs.
tact l0 and the above-mentioned threaded
These and other objects of my invention, as
sleeve 2.
well as the means proposed thereby for achiev
A helical spring I3 has one end in engagement
ing them, will ‘be understood from the following
with a corresponding eye formed by the body I,
description of the embodiment illustrated in the , while its other end enters into a bore of sleeve
drawing, in which:
member 1’. The spring 13 biases the sleeve mem
Figure 1 represents a cross sectional perspec
ber for rotation in the contact opening direction.
tive view of the cover portion appertaining to a
When the movable contact 9 is in engagement
plug-shaped thermal cutout according to the in
with contact Iii and under normal operating con
vention,
40
ditions, however, such rotation is prevented by
Fig. 2 represents a sectional perspective view of
a heat-responsive clutching spring is which is
the main portion of the same contactor,
frictionally seated on the upper portion 6 of the
Fig. 3 is a lateral view of the device showing the
stationary part 4!. The lower end of this spring
exterior of the main portion assembled with the
l4 (not visible in the illustration) is not attached
abovementioned cover portion, while
45 to any of the stationary and rotatable elements of
Fig. 4 is a part sectional view of some of the
the mechanism, while its upper end i5 engages a
elements shown in Fig. 1.
notch of the sleeve member "I. The winding direc
According to the drawing, a plug-shaped sup
porting body i of insulating material, such as
glass or ceramic substance, is provided with an
exterior metallic threaded sleeve 2 and a bottom
contact 3. The threaded sleeve 2 and the contact
3 are dimensioned and arranged so as to fit the
screw sockets customary for fuse plugs and the
like devices.
tion of spring ill is so chosen that the biasing force
of spring l3 tends to coil up the spring l4 and
hence to tighten the close ?t of its turns on the
peripheral surface of the stationary part 4. Con
sequently, as long as the clutching spring l4
remains cold, it maintains the movable contact
9 in engagement with the stationary contact to
55 once these contacts have been closed. Accord
2,411,352
4
bly opened by manual actuation after the cut
ing to a preferred feature of my invention and as
out has been reset. It will be understood that
illustrated in the drawing, the clutching spring
when manufacturing and assembling the device,
it consists of a helical bimetal winding which,
the depression is is produced only after all other
when su?iciently heated, expands its turns ra
dially and hence loses its grip on the stationary C71 parts are properly assembled.
The holding force of a clutch spring as repre
part 4, thereby releasing the member 1 with con
sented by the bimetal winding M in the above
tact 9 for rotation.
described embodiment is extremely great as com
An electric heater consisting of a Winding i8 is
arranged in the hollow of the stationary part 4.
pared with other releasable latching devices of
connection with movable contact 9. Hence when
around the entire periphery of the stationary
One end of the heater i6 is attached to the bot it? known type. This is due to the fact that the
frictional grip of the clutch spring is e?ective
tom contact 3 while the other end is in electric
the cutout is in circuit closing condition, a cur
rent path is formed from bottom contact 3
through heater it, movable contact 9 and sta
tionary contact is to the threaded sleeve 2. As
long as the electric current remains below the
rated value of the cutout, the diameter of the
part it and extends over a plurality of turns.
This great holding force has the advantage that
. the cutout cannot open the circuit accidently
when subjected to vibration or shock. Such dis
turbances are also rather ineffective on the clutch
grip because the clutch means according to the
invention have low inertia, and are symmetrical
bimetal winding i4 is so small as to retain con
tact 9 in the circuit-closing position in opposition . - and relatively balanced in static and dynamic re
spects as compared with unilaterally operating
to the bias of spring 23. When the current in
pawl or latch means. The use of a helical clutch
creases above the rated value and this overload
persists for a su?icient length of time, the bimetal
winding is heated and gradually expanded until
it releases its frictional grip on the stationary
part it and permits the spring l3 to move the
sleeve ‘7 and the contact 9 into the circuit inter
rupting position. Upon sufficient cooling of the
winding M, the sleeve 7 can be turned back into
the contact-closing position. Although in the
meantime, the turns of the bimetal winding l4
may have contracted to their original small
spring, especially of the bimetal type, has the
further advantage that it is not as subject to
ageing as are fusible elements. Thus while, for
instance, solder joints are apt to change their
overload characteristic upon repeated beatings
and operations, a device according to my inven
tion has considerably less tendency to develop
such changes in characteristic.
Referring to the illustrated embodiment, the
use of glass or other transparent material for part
It has the advantage that the bimetal strip is
heated not only by thermal conduction but, to an
diameter, the closing'motion of sleeve 1 and con
tact 9 is in the unwinding direction of the wind
ing l4, so that this motion causes mechanically a i: appreciable extent, also by heat radiation. As a
result, the bimetal strip is heated more rapidly
widening of the turns so that the friction be
at high overloads and hence respond more quick
tween elements 5 and M is insufficient to block
ly to especially detrimental current conditions.
this return motion. After the contact 9 has been
It will be obvious to those skilled in the art that
returned to the closing position, the spring [3
tends to move it in the coiling-up direction of the 40 devices according to my invention can be modi
fied in various respects, especially as to the de
winding ill so that the frictional grip becomes
sign and arrangement of its individual parts,
again effective and holds the sleeve ‘5 and contact
Without departing from the objects, features and
9 in the closing position.
advantages of the invention. Therefore, I wish
Substantially the same operation is obtained if
this speci?cation to be understood as illustra
the heater I6 is omitted, i. e; replaced by an ortive rather than in a limiting sense.
dinary conductor, so that the bimetal strip Ill
serves also as the heating element of the device.
While this is satisfactory for some current rat
I claim as my invention:
1. A contactor comprising, in combination, a
stationary structure having a cylindrical part, a
ings, it does not readily a?ord the possibility of
exchanging the heater for di?erent ratings.
50 member rotatable about said part and biased for
The supporting structure I of the cutout is
provided with a cover 5'? of sheet metal whose
peripheral portion l3 is turned at aright angle
rotation in one direction, contact means con
trol1ed by said member, a radially expansible
thermo-responsive spring winding connected with
said, member and frictionally seated on said part
and has a peripheral depression is which engages
a peripheral groove 20 of body I thereby secur
so as to prevent said rotation when cold, and
heating means for thermally expanding said
ing the cover I‘? in proper position. A resetting
winding in order to release said member.
knob 2! is rotatably mounted on the cover I1 and
2. A contactor comprising, in combination, a
has a centering projection 22 which enters into
stationary structure having a cylindrical part, a
the opening of sleeve 8 and has a ?ange 23 which
lies closely above the upper end of sleeve 8 when 60 member rotatable about said part and biased for
rotation in one direction, contact means con
the cover IT is properly attached to the body of
the plug. Projection 22 and flange 23 thus se
cure and guide the cylinder '11 in its proper posi
tion. A lateral projection 24 of knob 2|, when
the cover is attached to body I, engages the notch 65
trolled by said member, a radially expansible bi
metal winding having one end engaged by said
out entraining the sleeve 7 once the contacts are
closed. As a result, the contacts cannot be forci
pansible thermo-responsive spring Winding con
nected with said member and frictionally ‘seated
member and being seated on said part so as to
prevent when cold said rotation of said part, and
electric current-responsive heating means for
8 of the sleeve member ‘I. Hence, when upon an
thermally expanding said winding in order to re
operation of the cutout, the knob 2i is turned in
lease said member;
the‘ contact-closing or resetting direction, the
projection 24 abuts against the vertical end of
3. A contactor comprising, in combination, a
notch 8 and entrains the sleeve 1 and contact 9 70 stationary structure having a hollow cylindrical
part, a member rotatable about said part and
for motion in the same direction. Due to the
large peripheral length of notch 3, the projection
biased for rotation in one direction, contact
23 is free to move in the opposite direction with
means controlled by said member, a radially ex
5
2,411,352
on said part so as to prevent said rotation when
cold, and electric heating means disposed within
said. hollow part for thermally expanding said
winding in order to release said member.
ii
disposed centrally in its interior, a rotatable meme
ber surrounding said part within said support,
a stationary contact mounted on said support, a
movable contact controlled by said member for
4. A contactor comprising, in combination, a Cl engaging and disengaging respectively said sta
stationary structure having a hollow cylindrical
tionary contact, a spring disposed between said
member and said support for rotating said mem
part, a member rotatable about said part and
ber toward disengagement of said contacts, a
biased for rotation in one direction, contact
radially expansible thermo-responsive spring
means controlled by said member, a radially ex
pansible bimetal winding having one end engaged 10 Winding connected with said member and fric
by said member and being seated on said part so
tionally seated on said part so as to prevent said
as to prevent when cold said rotation of said part,
rotation when cold, and electric heating means
and electric current-responsive heating means
disposed within said support for thermally ex
disposed within said hollow part for thermally
panding said winding in order to release said
expanding said winding in order to release said
member.
member.
10. A thermal cutout for electric circuits, com
prising a plug-shaped hollow support, a cylindri
5. A contactor comprising, in combination, a
stationary structure having a cylindrical part, a
cal part stationary relative to said support and
member rotatable about said part and biased for
disposed centrally in its interior, a rotatable mem
rotation in one direction, contact means con 20 ber surrounding said part within said support, a
trolled by said member, a radially expansible
spring disposed between said member and said
thermo-responsive spring winding connected with
support for biasing said member in one direction
said member and frictionally seated on said part
of rotation, contact means having a stationary
so as to prevent said rotation when cold, heating
contact on said support and a movable contact
means for thermally expanding said winding in 25 controlled by said member, a radially expansible
bimetal winding having one end engaged by said
order to release said member for rotation in said
direction, and manually operable resetting means
for rotating said member in the opposite direc
tion.
6. A contactor comprising, in combination, a _
stationary structure having a cylindrical part, a
member rotatable about said part and biased for
rotation in one direction, contact means con
trolled by said member, a radially expansible
bimetal winding having one end engaged by said
member and being seated on said part so as to
prevent when cold said rotation of said part, and
electric current-responsive heating means dis
posed within said support for thermally expand
ing said winding in order to release said member.
11. A thermal cutout for electric circuits, com
prising a plug-shaped hollow support, a cylindri
cal part stationary relative to said support and
. disposed centrally in its interior, a rotatable mem
member and being seated on said part so as to
ber surrounding said part within said support, a
prevent when cold said rotation of said part, elec
tric current-responsive heating means for ther
mally expanding said winding in order to release
said member for rotation in said direction, and
manually operable resetting means for rotating
said member in the opposite direction.
stationary contact mounted on said support, a
movable contact controlled by said member for
engaging and disengaging respectively said sta
tionary contact, a spring disposed between said
member and said support for rotating said mem
ber toward disengagement of said contacts, a
'7. A thermal cutout for electric circuits, com
radially expansible thermo-responsive spring
prising a support, a stationary cylindrical part
disposed on said support, a substantially cylindri
cal member surrounding and rotatable about said
part and biased for rotation in one direction,
winding connected with said member and fric
tionally seated on said part so as to prevent said
rotation when cold, electric heating means dis
posed within said support for thermally expand
ing said winding in order to release said member,
contact means controlled by said member, a ra
dially expansible therrno-responsive spring wind
ing having one end engaged by said member and
being seated on said support for frictionally pre
venting said rotation when cold, heating means
for thermally expanding said Winding in order to
release said member for rotation in said direc
tion, and manually operable resetting means for
rotating said member in the opposite direction.
8. A thermal cutout for electric circuits, com
prising a support, a hollow cylindrical part rig
idly disposed on said support, a substantially ey
lindrical member surrounding and rotatable
about said part and biased for rotation in one
direction, contact means controlled by said mem
ber, a radially expansible bimetal winding having
one end engaged by said member and being
seated on said part so as to prevent when cold
said rotation of said part, electric current-re
sponsive heating means disposed within said hol
low part for thermally expanding said winding in
order to release said member for rotation in said
direction, and manually operable resetting means
for rotating said member in the opposite direc
a cover disposed on said support, and resetting
means arranged on said cover and engaging said
member for rotating it in the engaging direction
of said contacts.
12. A thermal cutout for electric circuits, com
prising a plug-shaped hollow support, a cylindri
cal part stationary relative to said support and
disposed centrally in its interior, a rotatable
member surrounding said part within said sup
port, a spring disposed between said member and
said support for biasing said member in one di
rection of rotation, contact means having a sta
tionary contact on said support and a movable
contact controlled by said member, a radially ex
pansible bimetal winding having one end engaged
by said member and being seated on said part so
as to prevent when cold said rotation of said part,
electric current-responsive heating means dis
posed within said support for thermally expand
ing said winding in order to release said mem
ber, a cover disposed on said support, and re
setting means arranged on said cover and engag
ing said member for rotating it in the engaging
tion.
9. A thermal cutout for electric circuits, com
prising a plug-shaped hollow support, a cylin
direction of said contacts.
13. A thermal cutout for electric circuits, com
prising a plug-shaped hollow support, a hollow
drical part stationary relative to said support and
cylindrical part stationary relative to said sup
2,411,352
7
8
port and disposed centrally in its interior, a rotat
able member surrounding said part within said
support, a, spring disposed between said member
and said support for biasing said member in one
part so as to prevent when cold said rotation of
direction of rotation, contact means having a sta
tionary contact on said support and a movable
contact controlled by said 'member, a radially
expansible bimetal winding having one end en
gaged by said member and being seated on said
said part, electric current-responsive heating
means disposed Within said part for thermally
expanding said winding in order to release said
member for rotation in said direction, a cover
disposed on saidrsupport, and resetting means
arranged on said cover and engaging said mem
ber for rotating it in the opposite direction.
'
GEORGE C. ARMSTRONG.
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