Improvements in Heat Regulators or Thermostats.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Heat Regulators or Thermostats.
I, WOLFF FREDERIK ENGELBRETH CASSE, of 16, Hortensiavej, Copenhagen,
Denmark, Civil Engineer, do hereby declare the nature of this invention to be as
follows:-
The unequal expansion of two solid bodies by heat has often been used for
regulating heating apparatus; thus two pieces of different metals have both
been heated, or two pieces of metal one only of which has been heated, and the
unequal expansion has been used to cause the approach or the removal of one
mechanical element from the other, whereby an electric circuit was closed or
broken, or a valve was opened or closed or the like, but no really satisfactory
result has been attained, because means have been wanting for transposing in a
sufficient degree and with the necessary exactitude the product of the great
pressure by the expansion and of the small measure of dilation into the product of
a large measure and of a smaller pressure.
This present invention solves the problem by letting the two bodies, the unlike
expansion of which by heat is to be used, to act upon a lever mechanism.
Just the same as it is possible by means of a common weighing apparatus to
transpose with an exactitude of 1/1000 or much beyond, the product of for instance
a load of 10,000 pounds and 0 millimetres motion into the product of
a load of 10 pounds and 20 millimetres motion; so is it also possible by combining
two metal rods, which are heated differently or prolonged differently by the same
heat, with a lever system, to measure with very great exactitude and certainty a
length difference in the two rods arising from the unlike heating of the said
rods, as a lever mechanism absorbs only a very small part of the work which is
brought upon one end of the lever. The product in question in this case consists
of the two factors viz: the difference between the rods used (a very small quantity)
and the power that under the influence of the heat expands the one rod (which is
a very large quantity), and this product can therefore be measured almost with-
out loss at the other end of the lever transposed in the manner that the lever
construction indicates.
As applied to the regulation of the heating of a liquid I use an upright brass
tube closed at each end and resting at its lower end upon a cone centre in an iron
frame, its upper end being provided with a hardened steel fork upon which rests
with a knife edge a double armed lever; the short arm of this lever bears against
an upper knife edge on the frame, while the long arm by a loop connected to a
knife edge on another double armed lever acts upon it, and this lever again by a
loop connected to a third such lever acts thereupon, this lever being by a cord
connected, to a valve or the like; which when moved effects an increased or
diminished heating of the liquid in question, which is led through the aforesaid
brass tube that is provided with an inlet and outlet opening.
In another form as applied to a bakers oven heated by the gaseous products of
combustion passing around it from a fire place the air is supplied to the fire place

page_text: by a pipe which can be closed by a damper hung in a chain or cord. A brass
pipe passes freely through holes in the front and back walls of the oven and is
neid at one end by a frame or staple outside the oven and not acted on by the
heat of the oven. At the other end the brass tube is provided with a hardened
steel fork which rests on the intermediate knife edge of an unlike armed lever
that is hung from a staple. Of the other two knife edges on the said lever one
is very near the intermediate knife edge and the other is many times further away
from it. A counterweight on the cord or chain pulls at that further end so that
every lengthening or shortening of the brass tube brings the damper hung in
the same cord down or up, and by attaching this damper higher up or lower
down it becomes possible to determine at what temperature in the oven the air
supply to the fire place is to cease and further access of heat to the oven to be
prevented. The cord is provided with marks to indicate the oven temperature at
which it is desired to work, and the damper can be shifted on the cord accord-
ingly. Over the counterweight is placed a graduated scale which by a pointer
on the cord indicates the temperature in the oven.
It is not absolutely necessary that the frame which carries the supports for
the brass tube should be outside the oven. But if it is to be placed so as to
become heated then metals or other materials having different co-efficient of
expansion must be used therefor and for the tube which works the heat regulator,
and the effect produced will then depend upon the difference between the ex-
pansive quality of the metals chosen.
Dated this 31st day of Tony 1807
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
Improvements in Heat Regulators or Thermostats.
I, WOLFF FREDERIK ENGELBRETH CASSE, of 16, Hortensiavej, Copenhagen,
Denmark, Civil Engineer, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement;-
The unequal expansion of two solid bodies by heat has often been used for
regulating heating apparatus; thus two pieces of different metals have both
been heated, or two pieces of metal one only of which has been heated. and the
unequal expansion has been used to cause the approach to or the removal of one
mechanical element from the other, whereby an electric circuit was closed or
broken, or a valve was opened or closed, or the like, but no really satisfactory
result has been attained, because means have been wanting for transposing in a
sufficient degree and with the necessary exactitude the product of a great pressure
due to expansion and a small movement or measure of dilation into the product
of a larger movement and a smaller pressure.
This present invention solves the problem by letting the two bodies, the unlike
expansion of which by heat is to be used, act upon a lever mechanism.
Just as it is possible by means of a common weighing apparatus to transpose,
with an error of but 1/1000 part or less, the product of, for instance, a load of 10000
pounds and 50 millimeter motion into the product of a load of 10 pounds and 20
millimeters motion, so it is also possible by combining two metal rods, at different
temperatures or which expand differently at the same temperature with a lever
system, to measure with exactitude and certainty a difference of length in the

page_text: two rods, arising from the unequal heating of the said rods, as a lever mechanism
absorbs only a very small part of the work which is brought upon one end of
the lever. The product in question in this case consists of the two factors viz.
the difference between the lengths of the rods used (a very small quantity) and
the power that under the influence of the heat expands the one rod (which is a
very large quantity) and this product can therefore be measured almost without
loss at the other end of the lever mechanism transposed in the manner that the
lever construction indicates.
In Figs. 1 to 7 is illustrated a form of apparatus for regulating the temperature
of a baker's oven, Figs. 1 to 3 showing the regulating device itself and Figs. 4 to
7 showing its application to a baker's oven.
Fig. 1 is a plan section through the oven.
Fig. 2 a side view and Fig. 3 side view in detail of the regulating device.
Fig. 4 is a plan of the oven, Fig. 5 is a section on line 1-1 of Fig. 4. Fig. 6
is a front view of the oven and Fig 7 is a section on line 2-2 of Fig. 4.
a' is the baker's oven which is heated by the gaseous products of combustion
passing around it from a fireplace. The air is supplied to the fire place or grate
by a pipe b which can be closed by a damper or plate el hung by a chain or cord.
A brass pipe g passes freely through holes in the front and back walls of the
oven and is held at one end d by an iron frame or staple e¹ outside the oven and
not acted on by the heat of the oven. At the other end the brass tube is provided
with a hardened steel fork see Fig. 3, which rests on the intermediate knife
edge m of an unequal armed lever f¹ that is hung from the staple e¹. Of the
other two knife edges on the said lever f¹ one, h¹, is very near the intermediate
knife edge m and bears upon a flat plane on the staple el, while the other , is
many, say 40, times further away from it than the knife edge m' is from the knife
edge h¹.
A counterweight k hung by a cord or chain pulls on the knife edge 2¹
on the long arm of the lever fl so that every lengthening or shortening of the
brass tube g¹ brings the damper or plate e hung by the same cord down or up,
and by attaching this plate higher up or lower down it becomes possible to deter-
mine at what temperature in the oven the air supply to the fire place is to cease
and further access of heat to the oven to be prevented. The cord is provided
with marks to indicate the oven temperature at which it is desired to work, and
the damper can be shifted on the cord accordingly, so that it can be made to shut
the air supply through the pipe b₁ sooner or later. By this arrangement the
damper can be made to shut off the air supply when a certain oven heat has been
reached. If the damper is for instance placed against the mark 220 on the
chain, the air supply will be shut off when an oven heat of 220° is reached, and
it will be automatically opened if the temperature in the oven goes below 220°.
Over the weight is placed a graduated scale which by a pointer on the cord
indicates the temperature in the oven.
The lever mechanism is so sensitive, even if the knife edges are not very sharp,
that with a lever arm proportion of 1 to 40 and an oven depth of 2125 meter
(7 feet) a variation in temperature of 5° C. (9° F.) can easily be read off. The
pointer and the damper e¹ in this example move 17 m/m for every ten degrees C.
of heat difference in the oven.
It is not absolutely necessary that the frame which carries the supports for the
brass tube should be outside the oven. But if it is to be placed so as to also
become heated, then metals or other materials having different co-efficients of
expansion must be used therefor and for the tube which works the heat regulator,
and the effect produced will then depend upon the difference between the expan-
sive quality of the metals chosen.
In Figs. 8, 9 and 10 is shewn an apparatus for regulating the temperature of a
liquid by operating a valve which controls the admission of a fluid-say for
example-steam.
A is a frame in which is inserted an upright metal tube B closed at each end
and provided with inlet Z and outlet Z', and with a longitudinal partition Y'

page_text: reaching from the upper end of the tube to nearly its bottom, so that the liquid
entering at Z is obliged to pass first down and then up through the whole length
before leaving the tube at 7. The lower end rests on a cone centre screw C in
the frame A while the upper end by means of prolongation piece D bears upon
the knife edge E provided on the first of three very unequal armed levers F G
and H that act on each other and turn on knife edges, the said levers having
their supporting points in the frame A or in a piece I fixed thereto.
The unequal armed levers F G and H are connected two and two by the links K.
The lever H does not act directly upon the steam valve P but upon a device now
to be described.
The lever H is by means of a link L connected to a two armed lever M turning
on a fixed pin. The lever M carries at its other end a rod N which below is
connected to one arm of a small bell crank lever O the other fork-shaped arm of
which embraces the spindle of a wheel Q having radial paddles and capable of
being moved a little laterally by means of the bell crank lever O. When the
paddle wheel is pushed quite to one side, the paddles are hit by a small jet of
water which always issues from the pipe R, while the paddle wheel when pushed
to the other side escapes the influence of the jet.
On the wheel axle there is a small tooth wheel S gearing with a sliding tooth
rack T which is guided by a roller U. One end of the rack is connected to a
double armed lever V which turns on the fixed pin W. The arms of this lever
are of very unequal length; its long arm is near the fulcrum connected to the
rod X for opening and closing the valve P. The short arm is provided with a
helical spring Y which tends to draw it to the right, Fig. 8.
The regulator acts as follows:
By raising or lowering the cone screw C the lever H is so adjusted that the
paddle wheel Q escapes the influence of the water jet. The tooth rack T will
then by the pull of the spring Y be in the position shewn in Fig. 8, which answers
to the steam valve being open.
When the temperature of the liquid rises above the normal degree, the pipe B
will be prolonged and by means of the levers F G H M and O pull the paddle
wheel so far to one side that its paddles meet the water jet, and the, wheel will be
rotated and its tooth wheel S draw the tooth rack T to the right. By this move-
ment the lever V will be turned and by the rod X act on the steam valve P so as
to close it against the tension of the spring Y.
When
The steam admission being now diminished the temperature of the liquid
drops. When the tooth rack T has gone quite over to the right a little stop
arrests its movement, the wheel Q stops and the valve P remains closed.
the proper lowered temperature has been reached the tube B contracts in length.
The levers F G and H drop by their own weight and thereby push the paddle
wheel to the left; at the moment that the liquid has acquired its normal tem-
perature, the tube B resumes its proper length and the paddles will then be just
out of reach of the water jet.
The paddle wheel being now not held by any force, the spring Y can contract,
whereby the lever V opens the valve P, the tooth rack being pushed to the left,
Fig. 9, and the paddle wheel, Q moves in the opposite direction.
This apparatus has been found to keep the liquid at a practically constant
temperature as the valve P by an augmentation of heat of only 1% C. closes
sufficiently to diminish the steam supply and lower the temperature of the liquid.
Figs. 11 and 12 shew another form of apparatus for regulating the temperature
of a liquid by the operating of a valve which controls the admission of a fluid-
say, for example-ammonia.
A is a heavy frame in which is mounted a metal tube B¹ resting on the lower
cone screw C¹ and having at its upper end a prolongation piece D¹ that bears
upon a knife edge E¹ on the upper of two combined very unequal armed levers F¹
H which turn on knife edges and have their supporting points in the frame A¹.

page_text: At the end of the lever H¹ there is a rod I' directly connected to a valve L'
which controls the admission of the ammonia.
The apparatus is used as follows:-
The lever H¹ is adjusted by raising or lowering the cone screw C¹ so as to just
close the valve L¹.
When the temperature of the tube B¹ rises above the normal, the tube B₁ will
lengthen and through the levers F and H raise the free end of the latter whereby
the valve L opens for the admission of ammonia until the temperature of the
tube B has gone down to the normal point. The tube B' will then shorten and
the levers will follow while the valve L' will close by reason of the pressure of
the ammonia upon it.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that with
reference to the construction of apparatus shown in Figs. 8 to 10 I do not claim
per se the water wheel device interposed between the lever mechanism and the
steam valve but what I claim is:-
1. In an apparatus, in which the expansion or contraction of a rod or tube is
utilized to indirectly regulate the amount of heat or cold, the combination with
the rod or tube, suitably supported at one end, of a simple or compound lever
mechanism, with the levers balancing on knife edges, operated by the other end
of said rod or tube on expansion thereof, a valve operated by said lever mechanism
for controlling the admission of a fluid which directly regulates the amount of
heat or cold, a weight or its equivalent for reversing the movement of the said
valve on the contraction of said rod or tube and means for adjusting the operation
of the said valve in relation to the desired normal temperature of the said tube
or rod substantially as set forth.
2. The construction of apparatus substantially as described and shewn with
reference to Figs. 1 to 7.
3. The construction of apparatus substantially as described and shewn with
reference to Figs. 8 to 10 and subject to the disclaiming clause.
4. The construction of apparatus substantially as described and shewn with
reference to Figs. 11 and 12.
Dated this 6th day of August 1898
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.