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Патент USA US2412142

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.3, 1946.
Filed April l0, 1943
`Patented Dec. 3K, 1946
Benjamin E. Gctchell, Plainville, Conn., assigner
to The Trumbull Electric Manufacturing Com
pany, Plainviile, Conn., a corporation of Con
Application April 1c, 194s, semi No. 482,559
7 Claims.
(ci. zoo-_isti
My invention relates to snap action switches
actuated by bimetallic members.
Vas a stop to limit the opening action by striking
against the upturnecl edge 20 of the support. It
The main object is te eliminate- the need for
will thus be seen that the trip member is sup
ported by the very member which acts as an
abutment for its open circuit action. This pre»
vents the stop from changing' even if the main
base or the insulating washer should be displaced
grinding and sharpening pivot points of the ther
mostatic switch.
Another object is to provide a simple reliable
device which can be commercially made and
readily adjusted.
or warp.
Another> object> is to provide a thermostatic
switch which can be adjusted without distorting
the bimetal member.
The bimetallic arm 2l has one end riveted to
the lug 22 which is -formed as an integral part
of the base l and oiiîset from the end 23 which
Another object is to provide a device which
is bent back over the adjacent top of the base.
does not readily get out of adjustment.
Another object is to provide a device, the parts
The other end of the arm 2i is connected by a
gf which can be economically made and assem
Fig. 1 is a plan view of a switch embodying
one form of my invention.
Fig. 2 is an edge view of the same. '
metallic arm can be so adjusted as to normally
hold the circuit closed or open. Preferably an
insulating piece 25 is interposed between the arm
and the spring.
. Fig. 3 is a rear view of the same.
Adjustment of the bimetallíc arm can be read
Fig. d is a plan view of the blank from which
the base is formed on a reduced scale.
Fig. 5 shows a, plan and edge view of the con
tact trip member.
snap action spring 2t to the trip member l5 be
tween the contact 8 and the hinge line. The bi»
Fig; 6 shows a plan and edge view of the sup
port for the contact trip.
Fig.. 7 is an enlarged detail view showing the
means for supporting the contact trip member.
ily eíected by tightening or loosening the screw
26 which is screwed into the base and engages
the underside of the end 23 to bend the end more
or less. lt will be seen that such adjustment
»' does not bend or distort the arm 2l at all but does
change its position by reason of the movement of
the lug il?. with. the end 23. The end is sui’il
eiently resilient to automatically return to ,its
The base ‘l is of sheet metal, for instance steel.
former position when released by retraction of
The switch contacts 8, S are carried by one end 30 the screw.
of the base butv suitably insulated from it for in»
The type of línìfe edge support of the movable
stance by ñbre washers IIl, II. The stationary
trip member very simple and easy to make as
. Contact 8 has a soldering lug l2. The support i3
it does not require grinding or fitting of pivot pins
is preferably of phosphor bronze and riveted to
or bearings. By bending a part of the blank of
the base but insulated from it and provided with
the Contact trip member i5 at an angle of 45°
a ‘wire terminal i4 at the back. it may have a
to its main anis, the corner of the cut edge Il
small boss i3' projecting into the insulation ll
.formed in blanlring theipiece from sheet metal
so as to hold the support in proper alinement, the
serves as a sharp edge similar to a knife edge.
metal base being cut away as at ‘I’ to avoid con
The angle it formed by stamping the post is
tact between the metal parts.
The trip member I5 which carries the movable
contact S is preferably of hard brass and hinged
to the support I3. A knife edge hinge bearing is
40 made slightly greater than 90° and serves as a l
stationary bearing for this knife-like edge il.
It will be noted that the thermostatic member
in this switch is simply a straight strip-all ad
elîected in a very simple manner. The support
justment is eiîected by movement of a part of the
I3 has two upstanding posts li’ formed with 45. base. This adjustment can easily cover a range
of operation of the thermostat from below 0 de
bent angle recesses i6 of slightly over 96° angle
grecs to about 300 degrees F.
to receive the sharp cut edges Il formed in blank
in'g the trip member from sheet metal and which
The differential between the “on” and “on”
positions of the trip member I5 can be adjusted
constitute the pivot or hinge of the trip mem
ber I5. The lugs I8 of the trip member beyond 50 by bending the tail piece I9 to increase or de
the knife edges extend past the posts I4’ so as to
crease the break distance between the contacts
prevent sidewise displacement. The tail piece IS?
extends from the trip member in the direction
opposite to the Contact 9 and serves partially to
counterbalance the trip member and also to act
8 and 3.
I claim:
1. A thermostatic switch comprising a base; a'>`
trip contact 'member hinged at one end of the
base, the opposite end of the base having a return
bend with an offset lug cut from an intermediate
part of the base and extending away from the
tionary support formed with angularly disposed
fiat portions providing an open angle recess at>
least slightly over 90° and of substantial length,
a movable member having its body blanked from
and connected to said trip contact member and 5 sheet metal, said body having end portions dis
posed in the same plane, one of said end portions
an adjusting screw in the base adapted to-engage
carrying a contact member and the other end
and move the return bend and lug of the base «
portion acting as a stop and counterbalancing»
for varying the action of the bimetal arm.
member, the portion of said body between said
2. A snap switch having a sheet metal support
with a supporting post bent to form two ñat 10 end portions being bent out of the plane of said
contact end, a bimetal arm secured to said lug
angular portions providing an open angle recess ‘
end portions and being provided with an elon- --
slightly over 90°, a movable .contact carrying
gated edge portion cut at right angles to the plane '
member blanked from sheet metal and bent so as -
of the adjacent portion thereby forming right
angled corners, said member and support being~ so '
to present a right-angled corner of a cut edge
» into the angle recess, the corner of this cut edge 15 positioned relatively that a sharp corner of said
cut edge portion provides a knife-edgedpivot for
thereby forming a sharp edge pivot for the mov
the movable member in the open angle recess of
able contact member.
the support.
3. A snap switch having a sheet metal support
6. In an electric switch, a stationary member
with a supporting post bent to form two fiat
angular portions providing an open angular re 20 formed of sheet metal with- an elongated open
angle recess in one surface formed by bending
cess slightly over 90°, a movable contact carrying
one portion with respect to the adjacent portion,
member blanked from sheet metal and formed
the walls of said recess extending at an angle of
vwith a cut edge sheared at right angles to the
more than 90° with respect to each other, a mov
adjacent surface and bent so as to present a
right-angled corner of said cut edge into the 25 able member pivoted in said recess, said movable
member being blanked from sheet metal and
angular recess, said corner. forming a sharp edge
having. an. elongated edge cut at substantially
pivot for the movable contact member and spring
right ~angles to the adjacent metal so as vto pro
means for normally holding the corner of the
vide a sharp-.corner at one surface, said corner
edge against the corner of the angular recess.
4. A thermostatic switch comprising a base 30 being seated in said recess andserving to support `
said movable member in the manner of a knife
member having a flat body portion with one end
thereof bent backwardly upon but spaced from -
the body portion, an integral lug portion carried
by said bent portion,` a stationary contact carried
'7. A thermostatic switch having a sheet metal '
support with two upstanding integral posts bent
by said base, a movable contact, a bimetal arm
having one end fastened to said lug portion and
its other end connected to said movable contact
for actuating the same and means for adjusting
to form angular recesses, a sheet metal trip con
the position of said arm including a screw mem
angles to the main surface and a bimetal arm
tact member having spaced-apart cut vedges
forming knife edges seated in said recesses, said
edges being formed by shearing the metal at right
ber carried by and movable through said base 40 having one. end stationary and a spring extending
between the posts and connecting the other end
into the space between said bent portion and
of the bimetal arm to the trip member and hold
the base and directly/,engaging said bent portion
ing the cut edges in the recesses.
for adjusting the relative position of the arm
and base.
5. For use in an electric switch having a sta 45
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