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Патент USA US2121582

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June 2l, 1938.
Filed Sept. 5, 1956
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- Edward ßZe/z.
Patented June 21, 1938 f
Edward Bletz, Lexington, Ohio, assignor to West
inghouse Electric & Manufacturing Company,
East Pittsburgh, Pa., a corporation of Penn
Application September 5, 1936, Serial No. 99,619
2 Claims. (Cl. 200-139)
This invention lrelates to thermostats, and more
particularly, to thermostats having a bimetallic
disc with a snap action.
It is an object of this invention to so arrange
The underside of the plate I is covered with
insulation || and a wire or auxiliary heater I2
is embedded in the insulation II to carry a heat
ing current when it is desired to heat the ther
'I'he bimetal disc I Il' is dish-shaped, as shown
device as a whole is compact. This provision is clearly in Figs. l and 2. Its center is supported
particularly adapted to the control of direct- ,. by a nut ,|3, by which the center of the disc It
current circuits, in which the arcing conditions is. secured between the threaded member 8 and
5 the parts of the thermostat that provision may
be made for alarge arcing space and yet, the
10 are more severe because the arc is likely to en
said nut I3 at the bottom of the member which 10
is threaded into the hub 4. The spindle or mem
It is a further object of this invention to mount ber 8 is provided with a stem I5 and a head i5
the contact-controlling members on the other by which it is manipulated.
face of the main base plate from the blmetalli
Upon the upper face of the base plate I arcu
15 disc.
ate conducting members I1 to 2| are secured.
It is a further object of this invention to pro
These members lie with their ends adjacent each
vide means whereby the distance of the bimetallic other forming the outline of a circle. Any other
disc, and simultaneously the distance of the mov
closed plane ligure would do as well. The end
able contact members from the base plate, may members I1 and 2| of the outline formed by
20 be controlled.
the conducting members are connected to leads 20
Other objects of the invention and details oi’ 24 which extend to the external circuit which
the structure will be apparent from the follow? is provided .with direct current by any suitable
ing description and the accompanying drawing, means. The members I1 to 2| include a member
in which:
I3, which is in two parts connected by a bridg
Figure l is a sectional view taken through the ing portion 25 where the member I 8 is laterally
center of the thermostat when occupying one deformed to accommodate the passage of a fas
` position;
tening member 21. A hole 28 in the plate I
Fig. 2 is a view in side elevation showing the accommodates the member 21.
thermostat in the opposite position;
'I'he member 21 is best shown in Figs. 6 and 7.
so Fig. 3 is a top plan view of the base plate;
It consists of a cylindrical rod, the upper por 30
Fig. 4 ls a similar view of the ring which car
tion of which is threaded and the lower portion
ries the contact buttons;
29 of which has a rectangular cross section, as
Fig. 5 is a plan view of the bimetallic disc;
best seen by comparing Fig. 6 with Fig. 7. The
Fig. 6 is a detailed elevation ci a securing rectangular end 29 of the lower portion of the
35 member for the disc; and
rod 21 extends through an opening 30 in the 35
Fig. 7 is a side view of the same member.
bimetallic disc III. 'I‘he opening 30 is oval, its
In the drawing, the base member I is a foun
long dimension being radial of the disc. When
dation plate upon which the thermostat is the rod 21 is in such position that the long di
mounted, and is secured in whatever position mension of its head 29 is in line with the radius
40 the thermostat is to be used; It consists of an
of the disc, it is readily passed through the
annular plate having a central opening 2 in opening> 30. When the rod is so turned that its 40
which the hub 4 is mounted. The upper sur
head is in a position at right angles to this, it
face of the plate I is covered with a layerl of cannot be withdrawn from the disc. There are
mica or desired insulation 3, which is provided openings in the insulation, and in the foundation
45 with a central opening to accommodate the hub
plate I through which the rods 21 are passed, 45
4. The central part of the plate I is covered and at their upper end they are threaded into a
with a supplemental sheet of insulation 5, which ring 3| and secured in place by lock nuts 32.
is also perforated in the center to accommodate
ring 3| is thus constrainedv to move with
the hub 4. Immediately adjacent the hub 4 theThe
disc III when the disc Ill changes its con
is a protective plate 1 which permits the upper ñguration. The ring 3| carries contact buttons
end of the hub to be peened over Without in
which serve to bridge the gaps between portions
juring the insulation. The hub 4 is threaded and
I1 to 2|. The contact buttons are .shown in Fig.
supports a threaded member 8 by means of which
l at 35, in their circuit-closing position, and are
a bimetallic disc IU is operatively heldin place shown `in Fig. 2 in their circuit opening posi-'
55 .below the plate I.
tion. As' best seen at the left of Fig. 1, where 55
dure longer.
In the position shown in Eig. 1, the several but
one of these buttons is shown in section, it com
prises a button proper 36 which is fastened in . tons 35 bridge the éorresponding gaps in the
outline i1 to 2|, and in doing so each button tilts
place by a rivet 31. The button is countersunk
about its pivot as much as may be necessary to
so that it can readily tip. The rivet 31 has on
accommodate itself to the out-of-le‘vel position
Gi the lower side of the ring 3| a convex washer
38 by which the tilting movement of the button of the ring 3| or to the lack of uniformity in the
36 can be accommodated.
The convex washer
When the device is in the cooled position, r0
mica or other insulation 39, and a second washer
tation of the head I6 may cause the threaded
of insulation at the upper side of the ring co1n~
member 8 to rise in ‘the hub 4. This will draw
the central part of the disc I0 upward but the
rods 21, being secured in the holes 3U, prevent
the peripheral part oi.' the disc from rising. The
curvature of the disc may thereby be increased.
If the head i6 is rotated in the opposite direc
tion, the curvature may be lessened because of
similar considerations. By this adjustment, the
critical operating temperature of the disc may
pletely insulates the button from the ring. ‘The
rivet 31 passes through the center of the insulat~
ing washers and the hole in the ring 3i which
accommodates it is so large that the rivet does
not contact the ring.
Upon the underside of the base plate I three
stops 40 for limiting the upward snap movement
of disc I0 are secured by means 0i" stems 4I,
which pass through the plate I but do not go
through the insulation 2. Such a stem is shown
at 4| at the left of Fig. 1. The stops lli and their
securing stems are indicated at 4| in Fig. 3,
but the rods 21 are not shown in this figure.
The holes which accommodate the rods 21 are
shown at 2B.
In the operation of the device7 considering the
parts in the position illustrated in Fig. i, the
bridging members or buttons 35 bridge the gaps
between the several contact pieces I1 to 2|. Be
30 ginning at the contact block l1 and proceeding
clockwise in Fig. 3 around the outline of a circle,
there is a gap at a stop 4i, then the 'long block
I8 passes the pin 21 (represented by the hole '23)
and a second gap occurs at the next stop 4 I, after
which the block I9 occurs which is connected to
theAblock 2|] by the wire I2. This wire affords
a bridge around the gap where the second pin 21
occurs. The block 20 is separated from the block
2| by another gap in which a stop 4| occurs.
Al I)
The blocks I1 and 2| ail'ord terminals to which
loe predetermined.
When the disc snaps to the open position, it
does not move an indefinite distance, but its up~
per movement is limited by the stops 4|). The
points in the disc which abut the stops il! are
near, but not at the periphery. ‘When ‘the disc
in the position represented by Fig. 2, adjust» 25
ment oi' ‘the head I6 may cause the disc to change
its coniiguration because vits periphery is heid
by the stops lli i’roni iurther upward movement.
Ii the head I6 is turned in the direction to cause
the disc to descend, its coniiguration need not 30
thereby he changed because the rods 21 and the
ring 3| can descend with it. No eii'ect, except an
increased tendency to snap, can occur from ro
tation of the head IE when the parts are in the
Fig. 2 position, but in the Fig. l position, the 35
pressure between the buttons 35 and the contact
members I1 to il can be regulated by `turning the
head I6.
Variations in the details of construction may
be made within the skill of these skilled in the 40
the leads 2l are connected. The direct-current
circuit, which includes the leads 2l, sends a cur
art. ' The specific illustration and description of
one form of the device is not to be considered a
rent from the block I1 through the several bridg
ing contacts and block 2| and thence into the
circuit including the leads 24. A gap containing
a pin 21 lies between blocks 2| and l1 but this
ily required by the prior art,
is never bridged.
When the device becomes hot, either by the cur
rent through the wire I2 heating it or by the
surroundings being hot or both, the disc ID be
cause of the unequal expansion of its two layers,
reaches a configuration of unstable equilibrium,
and then snaps abruptly to the position shown in
Fig. 2. In this movement the rods 21 are pushed
upward and in consequence, the ring 3| is ele
vated. This separates the buttons 35 from the
conductive members I1 to 2| and breaks the cur
rent through the circuit I8.
If this current is heavy, the breaking may be
thicknesses of the parts Il to 2|.
38 is separated from the ring 3| by .a washer of
limitation. The only intentional limitations are
those expressly stated in the claims or necessar»
I claim as my invention:
1. In a thermostat, a base plate, a thermally
responsive disc adjustably mounted on the base
plate at one face thereof, a carrier on the other
side of said base plate from said disc, means se
accompanied by an arc across each of the sev
eral gaps. When this occurs, it is desirable that
the arc shall not act upon the bimetallic disc III,
either to heat it or to increase corrosion. This
cured to said disc near the periphery thereof and 50
mechanically securing it to the carrier, conduc
tive members separated by gaps and insulated
from, but secured to, the base plate on the face
toward the carrier and forming an'outline hav
ing adjacent ends, leads united to the end ones
of said conductive members, bridging pieces, one
for each of the gaps, except the gap separating
said end conductive members, said bridging
pieces being mounted on, but insulated from, the
carrier, the mounting of said disc including 00
means for moving the center thereof to vary its
distance from the base plate whereby with the
is prevented by the circumstance that the disc Ill
is on the other side of the foundation plate I,
and because of the several _sheets of insulation
segregating the region where the arcs form. The
ring 3| and consequently, the button' 3l, are
disc will vary the pressure oi’ the bridging mem 05
bers against the conductive members and also
the coniiguration oi' the disc.
moved so far from the conductive members I1
to 2| that the arcs are extinguished.
When the parts cool, the disc lil is strained in
the opposite direction and after passing a cer
tain critical temperature, it snaps back to the
position illustrated in Pig. l. This movement
brings the ring 3| abruptly downward toward
the foundation plate l.
bridging pieces in contact with the conductive
members, adjustment of the mounting of the
2. In a thermostat, a base plate, a thermally
responsive disc adiustably mounted on the base
plate at one face thereof, a carrier on the other: 70
side of said base plate from said disc, means se
cured to said disc near the periphery thereof and
mechanically securing it to the carrier, conduc
tive members separated by gaps and insulated
from but secured to the base plate ou the iaoe
toward the carrier, leads united to the end ones
of said conductive members, bridging pieces, one
for each of >the gaps, except the gap separating
said end conductive members, said bridging
pieces being mounted on, but insulated from, the
carrier, the mounting including means for per
mitting a tilting movement of the bridging pieces
relative to the carrier, whereby the bridging
pieces will always contact the conductive mem
bers fiatly.
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