Патент USA US3162758

Dec. 22, 1964
R. |_. VlCENZl ETAL
3,162,742
THERMALLY ACTUATED ARCUATE STRIP T‘VZPE CONTROL DEVICE
Filed Jan. 22, 1962
INVENTORS
Reno L. \hcmm
JOHN A. Kuzm?a
E‘;
ATTORNEY
United States Patent 0 " ICC
EJhZQMZ
Patented Dec. 22, 1964
2
With reference to the drawings, a mounting bracket in
has a front web 12 which supports rod 14. A strip 16
has its outer end spot welded or otherwise connected to
the outer end of rod 14. The inner end of strip 16 is
3,162,742
THERMALLY AtCTUATlED ARQ‘UATE S'l‘l'tlil’ TYPE
@GNTRUL DEVICE
Reno L. Vicenri and .lohn lifleinheinz, Riverside, (Iali?, 5 connected to a sliding shaft 18 which has a square cross
assignors to Controls Qoinpany of America, Schiller
section and projects through a cooperating hole in the
Park, Ill, a corporation of Delaware
web which prevents twisting of the strip during calibra
Filed Jan. 22, 19%, Ser. No. 167,573
tion which will be described hereinafter. The inner end
'7 Claims. (@l. Nth-137)
of this shaft carries a threaded stud 26 having a washer
This invention relates to a flame or temperature re
22 mounted thereon to provide a shoulder against which
sponsive control of the type generally used to sense the
a leaf spring 24 bears to preload the strip toward actua
presence or absence of a ?ame in order to control the
flow of fuel to a burner.
tion. The ends of the leaf spring are anchored in corners
provided by the inturned flanges 26 on the front web.
A spring bracket 28 is threadedly mounted on stud 29
and hasrone end of a U-shaped leaf spring 3t) riveted to
portion 331 of the bracket. The other end of leaf spring
30 projects through an aperture 32 in portion 33 of the
bracket to bear against a cross member 34 of portion 33.
The force exerted by spring 34} is greater than the force
required to operate switch 36 by means of its plunger 38.
Therefore, spring 30 provides for direct transmission of
actuating movement between strip 116 and the switch and,
Devices of this type generally fall into one of two types,
the ?rst being a rod enclosed within a tube and the sec
end being a strip mounted adjacent a rod or tube. The
two elements in either type are interconnected at one
point and are provided with different temperature co
efficients of expansion so that differential movement be
tween the two elements can be employed to effect a con
trol function, generally the actuation of a switch. Both
types are subject to fatigue and failure by reason of
warpage of one or both of the elements. The rod and
tube type is probably the more durable of the two but,
on the other hand, is less responsive than the strip type.
The present invention relates to the strip type and
has for an object the provision of a strip con?guration
which is highly resistant to warpage and consequent fail
ure as found in the prior art while retaining the high
speed response characteristics inherent in heating a thin 30
strip of metal.
This invention more particularly pertains to controls
in the normal operating range of the switch, the spring
will be in the position shown in FIG. 1 but if the strip
should expand beyond the point at which the switch is
actuated this overtravel is taken up by lifting spring 3%
off cross piece 34 thereby preventing overload of the
switch or distortion of the parts.
It should also be noted that, in addition to providing
a direct connection between strip and switch, the com~
bination spring and bracket provides for accurate and
facile calibration. Bracket 28 can be rotated on stud Ztl
of a type which are generally considered to be tempera
to vary the position of spring 30 relative to plunger 33
while maintaining both the direct connection between
ly referred to as flame sensors. While the present con— 35 strip and switch and the overtravel feature. The bracket
?guration can also be classi?ed as temperature responsive
and spring can be suitably ?xed in a particular relative
it is proper to refer to it as being ?ame responsive in that,
position to achieve a desired calibration and, since there
when installed in accordance with the design parameters,
will be virtually no wear of the spring and bracket, the
the control can be operative to sense a flame while under
original calibration will not be changed during usage.
similar environment conditions it would be insensitive to
Strip in has an arcaute con?guration throughout the
ture responsive even though in practice they are frequent
temperature in the sense that if the temperature of both
the strip and the rod are the same the device would be
non-responsive. In other words, while we prefer to use
materials having different temperature co-e?icients of ex
pansion, it is feasible to employ materials having the same
temperature co-e?icients and still have the device respon
sive to flame although it would obviously not respond to
temperature since there would be no differential in move
ment.
Another object of this invention is to provide a con
major portion of its length with the degree of curvature
being selected so as to provide uniform spacing between
the strip and the rod at any point where a cross-section
.would be taken through both of them as for example,
in FIG. 3. This device is preferably arranged so that
the ?ame impinges on the strip as indicated in FIGS.
2 and 3. Under these circumstances it will be apparent
that rod 14 lies in the shadow of the strip and, hence, is
not subjected to the direct heat of the ?ame. This pro~
50 vides uniform temperature across the rod and prevents
struction which is easily calibrated and which will retain
Warping of the rod. The curvature of the strip accom
its calibration throughout its operational life. in doing
plishes two purposes. A ?at strip tends to concentrate
this we have provided for direct actuation of the switch
the heat along the edges causing rippling of the edges and
through an adjustable interconnection between the strip
ultimate failure whereas the curved strip places the edges
and the switch. This interconnection has a direct action 55 a little further from the flame and tends to equalize the
on the switch rather than employing any levers or the
temperaturesexisting across the strip. Furthermore, with
like to multiply the motion. As a result there are no
factors such as bearing wear to disturb calibration. The
interconnection also permits a simple arrangement for
preventing overloading the switch.
The novel features of this invention will be set forth
in the appended claims. The invention itself, together
with additional objects and advantages thereof, will be
more clearly understood from a reading of the following
description in connection with the accompanying draw
ings wherein a preferred embodiment of this invention
is illustrated and in which:
FIG. 1 is a front elevation of the control mechanism
partially in cross-section;
the strip being generally uniformly spaced from the rod
the strip can uniformly radiate heat to the rod. The
result is that the strip exhibits no edge warping or distor
60 tion even after prolonged use.
in operation the ?ame will impinge on the strip as
noted above and this will occasion the strip expanding at
a very rapid rate as compared to the rate of expansion
of the rod lying in the shadow of the strip. As the strip
expands the loading spring 24 will move the threaded stud
to the right carrying the switch actuating spring and its
bracket to the right to actuate the switch through its
plunger. in the usual situation switch as would be the
normally open type which would be closed in response
70 to the flame to establish a circuit permitting a fuel valve
PEG. 2 is an end view of the mechanism; and
PEG. 3 is a cross-sectional view taken along lines 3-3
to open if the other parts of the control system so require.
of FIG. 1.
When the flame is extinguished the strip will cool off
3,162,742
3
if
rapidly, because of its low mass, and will open the switch
within a short period of time after ?ame failure.
To maximize the responsiveness of the control it is
obvious that the co-e?icient of expansion of the strip
should be higher than that of the rod. With this situation
should the temperature of the rod tend to stabilize close
to the temperature of the strip the difference in the co
further characterized by said heat source being arranged
exteriorly of said control device so that said control device
can be arranged with said one member disposed inter
efficients will insure response of the control, such a con
mediate said heat source and said other member.
4. A control device adapted to respond to a dame com
prising, in combination, a frame, a switchesupported on
said frame, a rod ?xed to said frame, a strip connected at
one end to said rod and extending longitudinally of and
trol would be fully temperature responsive.
in spaced relation to said rod, said strip being generally
t is possible
to mount the actuator end of the strip in such a manner 10 arcuate in transverse cross~section and uniformly spaced
as to increase the spacing betweenthe strip and the rod
and under these circumstances it is less likely that the
strip and rod temperatureswill equalize. ~It is also feasible
to make the strip and rod of the same material and rely
on the shadow effect, i.e. the rod being in the shadow of
from said rod in any transverse plane through said rod
and strip along the longitudinal extensions thereof, said
strip arranged with the concave side thereof toward said
rod and arranged in said control device so that saidcon
trol device is adapted to be disposed with said strip in
the strip, and the temperature'dilferential resulting from
termediate said rod and ?ame, a threaded stud con
nected to the free end of said strip, a support member
this to have a control that will respond to the flame where
as the control would not respond to temperature alone.
threadably engaging said stud and a spring mounted on
The discussion and description of this invention in con
said support member and engaging said switch, said spring
nection with a particular preferred embodiment thereof 20 being mounted to directly transmit motion of said strip
has been for illustrative purposes only and should not be
to the switch and mounted to yield upon movement of
taken by way of limitation. Accordingly, it is intended
said strip beyond that required for switch actuation.
in the appended claims to cover all modi?cations and em
5. The combination ‘of claim 4 including spring means
bodiments of this invention as fall within the true spirit
for preloading said strip inthe direction of actuation of
and scope thereof.
said switch.
What we claim is:
6. A control device adapted to respond to a heat source
1. A'control device adapted to respond to a ?ame or
comprising, in combination, a frame, a switch supported
variation in temperature comprising, in combination, a
on said frame, a rod ?xed to said frame, a strip connected
at one end to said rod and extending longitudinally of and
frame, a switch supported on said frame,.a rod ?xed to
said frame, a strip connected at one end to said rod 30 in spaced relation to said rod, said strip beinggenerally
and extending longitudinally of and in spaced relation to
said rod, said strip being generally arcuate in transverse
arcuate in transverse cross-section anduniformly spaced
from said rod in any transverse plane through said rod
cross section and uniformly spaced fromsaid rod in any
and strip along the longitudinal extensions thereof, said
transverse plane through said ‘rod and strip‘ along the ion
gitudinal extensions thereof, said strip arranged exteriorly
of and with its edges extending toward said rod, and
strip arranged with the concave side thereof toward ‘said
means connected to the free end‘ of said strip and engaging
rod and arranged in said control device so that said con
trol device is adapted to be disposed with said strip inter
mediate said rod and heat source, whereby said strip
said switch for transmitting motion of said strip to said
switch for actuation thereof.
is movable in response toexposure to said heat source,
and means connected to the free end of said strip and
2. A control device adapted to respond to a ?ame or a 40 engaging said switch to transmit'the movement of said
temperature variation comprising, control means, a gen
strip directly to said switch for actuation thereof, said
erally elongated ?rst member, a second member having a
last~mentioned means including spring means adapted to
con?guration conforming to said ?rst member and posi
tioned adjacent to and extending generally co-extensive
with said ?rst member, said second member disposed
externally of said ?rst member with its edges extending
toward said ?rst member and uniformly spaced from said
?rst member in any transverse plane through said ?rst
and second members along the longitudinal extensions
thereof, said ?srt and second members being intercon 50
nected with one of said members ?xed relative to said con
trol means so that in response to a temperature variation
the other of said members moves relative tosaid control
yield upon movement of said strip after actuation of said
switch.
7. A control device adapted to respond to a heat source
comprising, in combination, a frame, a switch supported
on said frame, a rod ?xed to said frame, a strip connected
at one end to said rod and extending longitudinally of
and in spaced relation to said rod, said strip being gen
erally arcuate in transverse cross-section and ‘uniformly
spaced from said rod in any transverse plane through said
rod and strip along the longitudinal extensions thereof,
said strip arranged with the concave side thereof toward
means, and means for connecting theother ‘of said mem
said rod and arranged in said control device so that said
bers to said control meansfor transmitting said motion
control device is adapted to be disposed with said strip
intermediate said rod and heat source, whereby said strip
to said control means for actuation thereof.
3. A control device adapted to respond to a heat source
comprising, in combination, control means, ?rst and sec
is movable in response to exposure to said heat source,
and means connected to said strip and engaging said
ond interconnected members exposed to said heat source,
switch for transmitting the motion of said strip to said
one of said members being ?xed ‘relative to said control 60 switch for actuation thereof.
means and the other of'said members being moveable
References .Cited in the ?le of this patent
relative thereto in response to exposure to said heat source,
one of said members having a con?guration conforming
UNITED STATES ‘PATENTS
to that of the other of said members and arranged inem
bracing relationship with a portion of said other mem
ber with its edges extending away from said heat source
and being uniformly spaced from said other member, and
means connecting said movable member to said control
means and transmitting movement of said moveable
member to said control means for actuation thereof; and 70
2,426,786
Newell _______________ __ Sept. 2, 1947
2,494,660
2,630,479
2,789,176
2,990,716
Kathe ________________ __ Ian. 17,
Villarreal ____________ __ Mar. 3,
Mercier ______________ __ Apr. 16,
Butts _________________ __ July 4,
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