Improvements in Thermostats.
Year: 1893

page_text: Date of Application, 11th Feb., 1893
Complete Specification Left, 11th Nov., 1893-Accepted, 16th Dec., 1893
Improvements in Thermostats.
I, ALEXANDER SHIELS, of 190 Bath Street, Glasgow, M.B., C.M., B.Sc., do
hereby declare the nature of this invention to be as follows:-
This invention relates to thermostats, and it has for its object to improve their
construction.
The invention refers to that class of thermostats, wherein the expansion and
contraction of mercury, spirit, salt and water, or other fluid sensitive to changes in
temperature, is made to operate the apparatus.
The invention is specially designed for use with refrigerating chambers, although
it may be used for other purposes.
In carrying out my invention, I preferably conduct the sensitive fluid from the
sensitive fluid pipes to a chamber, or its equivalent, in which is fitted a rubber or
other diaphragm, which I term the "regulating diaphragm." A spindle or rod
passes into the chamber, and bears, at its inner end, on the back of the diaphragm.
This piston, which is preferably provided with suitable guides, is held normally
downwards by means of a powerful spring, or a weight, or equivalent. The upper
end of the piston, if the thermostat is used for refrigerating chambers, is so
connected, by means of suitable links, levers, gearing or equivalent, to either the
valve for controlling the supply of steam to the refrigerating engines, or the supply
of refrigerating fluid to the chamber, as to, in its movements, operate said valve,
and so control the engines of the refrigerating fluid supply.
The sensitive fluid is also conducted to one or more chambers or equivalent, in
which is or are fitted diaphragms, which I term "safety diaphragms." The
"safety" diaphragms are normally held against the bottom of the chamber, by
means of a loaded piston, which is made to bear against them. The piston may
have, or may work in, guides, and the load may be a powerful spring or a weight.
The object of having one or more "safety" diaphragms is, in the event of the
temperature in the refrigerating chamber rising much above the normal, to allow
the sensitive fluid to continue its expansion after the "regulating" diaphragm has
reached its full limit of movement, and when any further movement would either
burst or injure said diaphragm, or injure the apparatus. The "safety" diaphragms
also obviate the necessity of resetting the machine after refrigeration has been
stopped.
The "regulating" diaphragm is preferably so arranged, that the whole expansion
of the sensitive fluid contained within the sensitive fluid pipes in the refrigerating
chamber, due to say a rise of 2° of temperature in said chamber, is taken up by it
within the limits of its full movement, and the "safety" diaphragms are preferably
so arranged that their full movement allows of the increased volume of sensitive
fluid, due to expansion by rise of temperature when the chamber is not being used,
being taken up. This limit of rise may, of course, be made as high as circumstances
demand it, say 93° F.
66
In order to ensure the satisfactory working of the "regulating" diaphragm, the
"safety" diaphragms are loaded to a much higher initial pressure than the
regulating "diaphragm, so that the full movement of the "regulating" diaphragm
is ensured before the movement of the safety diaphragms begin to take place.
The "safety" diaphragms are of, preferably, much larger area than the
regulating" diaphragm.
66
Suitable stops are provided to limit the movements of the diaphragms and
spindles, and also to support the diaphragms.
Instead of having a weight or spring as the load on the diaphragms, a closed

page_text: chamber, filled with compressed air or gas to the required pressure, may be fitted
on or over the diaphragms, in such a manner that the compressed air or gas presses
on and bears against the diaphragms. The air chamber may be fitted in any
suitable manner. This is very suitable where any slight variation of the pressure
of the air or gas in the chamber, due to variations of temperature, would not
interfere with the working of the apparatus. The air cushion serves to support
the diaphragms.
When loaded spindles are used, the movements of the diaphragms may be
transmitted to the spindle directly. In this case, a bearing plate, which fits on the
back of the diaphragm, and supports it, is provided. This plate may be circular
in shape, and be cut radially, so as to allow it to spread out or contract in area, and
to conform to the shape of the diaphragm..
Or the movement of the diaphragm may be transmitted indirectly through a
series of radiating plates, so arranged as to form a circle. The plates are hinged
or jointed articulately, at their outer ends, to a suitable ring or equivalent, secured
to the machine, and, at or near their inner ends or points, have sockets, in which
the lower ends of a number of rods or supports are movably fitted. The upper
ends of these rods or supports are, in a similar manner, fitted in the lower end of
the spindle, or a plate on the spindle. The plates normally hold the diaphragm
close down against the bottom of the chamber, and, when the diaphragm expands,
they move upwards, and, at the same time, support the diaphragm in its expanded
position.
Suitable stops are supplied to prevent the springs depressing the radiating plates
too far, and damaging the diaphragms.
Between the diaphragms proper and the plates or spindle, as the case may be,
false diaphragms, made of leather or other suitable material, for protecting
purposes, are or may be provided.
Instead of radiating plates, ordinary diaphragm plungers may be employed.
There may, if so desired, be two or more diaphragms combined and working
together.
The machine can, of course, be made more or less delicate, by restricting or
enlarging the full movement of the diaphragms to a certain number of degrees.
The sensitive fluid, before passing to the diaphragms, may be led into a storage
tank or reservoir of any suitable construction. This tank is used when it is desired
to employ a different fluid, and of a higher specific gravity to act on the diaphragms
than that used in the sensitive tubes. Secondary storage vessels may be employed
to contain an extra supply of sensitive fluid, and be suitably connected to the
system by pipes, provided with cut off valves. These secondary tanks are useful
for regulating and adjusting the action of the machine.
The bottom plates of the diaphragm chambers are preferably grooved, radially
or otherwise, on their internal surfaces.
The air chamber may be made in one with the diaphragm chamber, or form part
thereof.
The fluid in the storage tank may be a solution of salt and water, and the sensitive
fluid may be purified turpentine.
An electrical or mechanical device may be employed to indicate the temperature
in the chamber, and gauges may be used to indicate the pressure in the air
chamber etc.
The diaphragms may be made of india-rubber, copper or any other suitable
material.
Where more than one air chamber is used, they may be connected together by
suitable pipe connections, in order to equalize the pressure.
The movements of the "regulating" diaphragm may be transmitted, by means of
liquid pressure, to any suitable place at a distance.
Dated this 10th day of February 1903.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in Thermostats.
I, ALEXANDER SHIELS of 190 Bath Street, Glasgow, M.B., C.M., B.Sc., do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to thermostats, and it has for its object to improve their
construction.
The invention refers to that class of thermostats, wherein the expansion and
contraction of mercury, spirit, salt and water, or other fluid sensitive to changes in
temperature, is made to operate the apparatus.
The invention is specially designed for use with refrigerating chambers, although
it may be used for other purposes.
In carrying out my invention, I, preferably, conduct the sensitive fluid from the
sensitive fluid pipes to a chamber, or its equivalent, in which is fitted a rubber or
other diaphragm, which I term a "regulating diaphragm." A spindle or rod
passes into the chamber, and bears, at its inner end, on the back of the diaphragm.
This piston, which is preferably provided with suitable guides, is held normally
downwards by means of a powerful spring, or a weight, or equivalent. The upper
end of the piston, if the thermostat is used for refrigorating chambers, is so con-
nected, by means of suitable links, levers, gearing or equivalent, to either the valve
for controlling the supply of steam to the refrigerating engines, or the supply of
refrigerating fluid to the chamber, as to, in its movements, operate said valve, and
so control the engines for supplying the refrigerating fluid.
The sensitive fluid is also conducted to one or more chambers or equivalent, in
which is or are fitted diaphragms, which I term "safety diaphragms." The "safety"
diaphragms are normally held against the bottom of the chamber, by means of a
loaded piston, which is made to bear against them. The piston may have, or may
work in, guides, and the load may be a powerful spring or a weight.
The object of having one or more "safety" diaphragms is, in the event of the
temperature in the refrigerating chamber rising much above the normal, to allow
the sensitive fluid to continue its expansion after the "regulating" diaphragm has
reached its full limit of movement, and when any further movement would either
burst or injure said diaphragm, or injure the apparatus. The "safety" diaphragms
also obviate the necessity of resetting the machine after refrigeration has been
stopped.
The "regulating" diaphragm is preferably so arranged, that the whole expansion
of the sensitive fluid contained within the sensitive fluid pipes in the refrigerating
chamber, due to say a rise of 2° of temperature in said chamber, is taken up by it
within the limits of its full movement, and the "safety" diaphragms are preferably
so arranged that their full movement allows of the increased volume of sensitive.
fluid, due to expansion by rise of temperature when the chamber is not being used,
being taken up. This limit of rise may, of course, be made as high as circumstances
demand it, say 93° F.
In order to ensure the satisfactory working of the "regulating" diaphragm, the
safety" diaphragms are loaded to a much higher initial pressure than the
"regulating "diaphragm, so that the full movement of the "regulating" diaphragm
is ensured before the movement of the safety diaphragms begins to take place.
The "safety" diaphragms are of, preferably, much larger area than the
"regulating" diaphragm.
Suitable stops are or may be provided to limit the movements of the diaphragms
and spindles, and also to support the diaphragms.
Instead of having a weight or spring as the load on the diaphragms, a closed
chamber, filled with compressed air or gas to the required pressure, may be fitted
on or over the diaphragms in such a manner that the compressed air or gas presses

page_text: on and bears against the back of the diaphragms. The air chamber may be fitted
in any suitable manner. This is very suitable where any slight variation of the
pressure of the air or gas in the chamber, due to variations of temperature, would
not interfere with the working of the apparatus. The air cushion serves to support
the diaphragms.
When a loaded spindle is used, the movements of the diaphragms may be trans-
mitted to the spindle directly. In this case, a bearing plate, which fits on the back
of the diaphragm, and supports it, is or may be provided. This plate may be
circular in shape, and be cut radially, so as to allow it to spread out or contract in
area, and to conform to the shape of the diaphragm.
Or the movement of the diaphragm may be transmitted indirectly through a
series of radiating plates, so arranged as to form a circle. The plates are hinged
or jointed articulately, at their outer ends, to a suitable ring or equivalent, secured
to the machine, and, at or near their inner ends or points, have sockets, in which
the lower ends of a number of rods or supports are movably fitted. The upper
ends of these rods or supports are in a similar manner, fitted in the lower end of
the spindle, or a plate on the spindle. The plates normally hold the diaphragm
close down against the bottom of the chamber, and, when the diaphragm expands,
they move upwards, and, at the same time, support the diaphragm in its expanded
position.
Suitable stops are or may be provided for preventing the springs depressing the
radiating plates so far as to damage the diaphragms.
Between the diaphragms proper and the plates or spindle, as the case may be,
false diaphragms, made of leather or other suitable material, for protecting purposes,
are or may be provided.
Instead of radiating plates, ordinary diaphragm plungers may be employed.
There may, if so desired, be two or more diaphragms combined and working
together.
The machine can, of course, be made more or less delicate, by restricting or
enlarging the full movement of the diaphragms to a certain number of degrees.
The sensitive fluid, before passing to the diaphragms, may be led into a storage
tank or reservoir of any suitable construction. This tank is used when it is desired
to employ a fluid of a higher specific gravity, than that used in the sensitive tubes,
to act on the diaphragms. Secondary storage vessels containing an extra supply of
sensitive fluid may be employed and be suitably connected to the system by pipes,
provided with cut off valves. These secondary tanks are useful for regulating and
adjusting the action of the machine.
The bottom plates of the diaphragm chambers are preferably grooved, radially
or otherwise, on their internal surfaces.
The air chamber may be made in one with the diaphragm chamber, or form
a part thereof.
The fluid in the storage tank may be a solution of salt and water, and the sensitive
fluid may be purified turpentine.
An electrical or mechanical device may be employed to indicate the temperature
in the chamber, and gauges may be used to indicate the pressure in the air
chamber etc.
The diaphragms may be made of india-rubber, copper or any other suitable
material.
Where more than one air chamber is used, they may be connected together by
suitable pipe connections, in order to equalize the pressure.
The movements of the regulating diaphragm may be transmitted, by means of
liquid pressure, to any suitable place at a distance.
And in order that my said invention may be properly understood I have hereunto
appended three explanatory sheets of drawings, whereon,
Fig. 1 is a longitudinal section of the thermostat.
Fig. 2 is a plan.
Fig. 3 is a vertical section of a modification,

page_text: Is a cross section or
on the ime.
Fig. 5 is a plan of the cross head of the apparatus Fig. 3.
Referring to the drawings whereon the same reference numerals wherever repeated
indicate the same or similar parts-
1 is the regulating diaphragm, 2 the safety diaphragm, and 3 the storage vessel.
As will be seen at Figs. 1 and 2 the whole apparatus may be fitted on a bed plate
or foundation 4 the regulating diaphragm being at one end, the storage vessel at
the other, and the safety diaphragm in the centre. Of course, if so desired, the
parts may be arranged differently, thus, for instance, the storage vessel and
regulating diaphragm may be beside one another and at the back of the large safety
diaphragm.
The storage vessel consists of a cylindrical chamber 5, which, at its lower end,
is screwed into the dished bottom plate 6 and at its upper end into the convex
cover plate 7. The vessel is surrounded by a cylindrical protecting and insulating
casing 8. Fitted into the cover of the vessel is a branched casting 9, which is
bored with a vertical channel 10 and a horizontal channel 11. Coupled to the casting
by the cap and plug coupling 12 is a pipe 13 leading from the sensitive fluid tube
system fitted in the interior of the refrigerating chamber. This pipe communicates,
as shown, with the horizontal channel 11. 14 is a screwed spindle valve, which,
when screwed down, as shown, closes the upper end of the vertical channel 10.
15 is a vertical channel bored in the upper end of the casting and leading from the
channel 10 to the atmosphere.
The bottom plate 6 is made, as shown, with a downwardly projecting branch 18
which is coupled to the branch 19 of the pipe 17. The branch 18 is bored with a
central channel 16.
The pipe 17 has also branches 20 and 21 which are coupled, respectively, to the
downwardly projecting branches 22 and 23 of the safety and regulating diaphragm
chambers.
The safety diaphragm chamber consists of a concave bottom plate 24 and a
convex cover plate 25 which are secured to one another and to the foundation 4 by
means of the bolts 26. The safety diaphragm 2, which may be made of either
rubber or metal, is covered by a leather or other protecting diaphragm 2. Both
diaphragms are tightly secured between the flanges of the bottom and cover plates
of the chamber. 27 is a small hole in the cover plate 25. Mounted on the top of
the cover plate is a cylinder 28 which has screwed on its upper end a domed
cover 29. The lower end of the cylinder is screwed into a circular recess 30 cut
out of or formed in the cover plate. The cover 29 has an internally screwed
socket 31 cast on its upper end and into this socket a knee shaped casting 32 is
screwed. The channel 33 which is bored through this casting communicates with
the hole 34 in the cover 29. 35 is a screwed spindle valve fitted in the casting and
by means of which the channel 33 can be closed. 36 is a pressure gauge which is
fitted on the hollow branch 37 communicating with the opening 38 in the
cylinder 28.
The regulating diaphragm chamber consists of a slightly concaved bottom plate 40
and a recessed cover plate 41. The main diaphragın 42 is protected by leather or
other protecting diaphragms 43, 44, and by a helically coiled spring 45. The
spindle 46, has a piston or plunger 47 at its lower end which bears against the back
of the diaphragms. This piston or plunger works in the recessed part of the cover
plate 41. A tapered collar 48 is fitted on the spindle and round this collar a
powerful spiral spring 49 is fitted. This spring at its upper end bears against the
plate 50 which is supported on the pillars 51. 52 is a downwardly projecting guide,
around which the spring 49 is fitted, cast on the plate 50.
The upper end of the spindle 46 passes through a bushed opening 53 in the
plate 50 and is connected, as shown, to the short arm 54 on the horizontal shaft 55.
This shaft, which is carried in bearings 56, has, at its end, a long arm 57 which is
so connected by levers or other well known and suitable mechanism to the spindle
of the valve for controlling the supply of refrigerating fluid to the chamber (or

page_text: the valve for supplying motive fluid to the refrigerating engines) as to automatically
operate it.
The branch 15 of the casting 9 is for filling salt and water or other fluid into the
vessel 5; and compressed air or gas is forced into the chamber 28 through the
channel 33 in the casting 32.
In the modified form of the apparatus, as shown at Figs. 3, 4 and 5, the
movement of the regulating diaphragm (or it may be the safety diaphragm) is
communicated indirectly through a series of radiating plates 58, which, as shown at
Fig. 4, when fitted in place, form a circular plate or disc. The plates, which form
the cover of the diaphragm chamber, are made with bulbs 59 at their outer ends
which hinge or joint articulately into the annular recess or groove 60 made in the
covering ring 61. This ring, as will be seen at Fig. 3, fits into the recess formed
by the rim 62 of the bottom plate 40. The diaphragm 42, in this case, is
preferably thicker than in the construction shown at Fig. 1.
Each radial plate 58 has a socket or hole 63 in its upper side into which fits the
rounded lower end of a supporting rod or toggle 64. In Fig. 3, in order to show
the arrangement clearly, only two rods or toggles are shown. The rods or toggles
at their upper ends fit in sockets or holes made in a circular plate 65 secured to
the under side of the cross head 66 which latter slides on the guide pillars 67.
68 is a cross head fixed on the top of the pillars. The spring 49 is secured between
the cross heads as shown. The spindle 46 is in this case, secured at its lower end
to the cross head 66 and at its upper end passes through a central hole 69 in the
cross head 68. 61 are bolts.
If desired with the arrangement shown at Figs. 1 and 2 the movement of the
regulating diaphragm may be communicated to the spindle through an intermediate
bearing plate fitted at the back of the diaphragm.
With this construction of apparatus when the sensitive fluid in the tube system
expands under an increase of temperature it presses on the salt and water or
other fluid in the storage chamber 3 from which the pressure is communicated
along the pipe 17, to the safety and regulating diaphragms 2, 1. The
regulating diaphragm expands under the pressure and forces up the spindle 46,
thereby operating the valve for supplying refrigerating fluid to the refrigerating
chamber, or, as the case may be, the valve for supplying motive fluid to the
refrigerating engines. When the sensitive fluid contracts, under a decrease of
temperature, the diaphragm is relieved of the pressure and is forced to resume
its original position by the action of the spring 49.
The apparatus is so arranged that any slight increase of temperature in the
refrigerating chamber above a certain fixed limit is sufficient to force up the
regulating diaphragm against the action of the spring and open or partially
open the refrigerating fluid or motive fluid valve, as the case may be, so as to
increase the supply of cold to the refrigerating chamber and again reduce its
temperature to the normal. Likewise if the temperature in the chamber falls
slightly below the proper limit the action of the spring is sufficient to force
down the spindle 46 and close or partially close the supply valve so as to stop
or reduce the supply of cold and allow the temperature to again rise to the
normal.
If desired two or more safety diaphragms and chambers may be used and in this
case they would be connected to the regulating diaphragm chamber and to one
another by suitable pipe connections.
If desired the storage vessel
may be dispensed with and the sensitive fluid
pipes connected direct to the pipe 17. In this case of course the sensitive fluid
would act directly on the diaphragms.
If desired the safety diaphragm may be loaded by a spring or weight instead
of the air or gas cushion.
It is to be understood that I do not confine myself to the exact details of con-
struction shown on the drawings, as parts may be modified or altered without
departing from the invention.

page_text: 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 what
I consider novel and desire to claim is :-
1. The general arrangement and combination of parts of the apparatus,
substantially as hereinbefore described and shown on the drawings annexed."
2. In a thermostat, the combination with a regulating diaphragm of one or
more safety diaphragms which are loaded or supported by compressed air or gas,
substantially as and for the purpose herein before set forth.
3. In a thermostat, the combination with a regulating diaphragm of a storage
vessel containing a fluid of a greater specific gravity than the sensitive fluid in
the tube system, substantially as hereinbefore set forth.
4. The combination with the regulating diaphragm of a safety diaphragm con-
nected thereto and a storage vessel containing salt and water or other heavy fluid
interposed between the diaphragms and the pipes containing the light sensitive
fluid, substantially as hereinbefore set forth.
5. In thermostats having working diaphragms the application and use of a com-
pressed air or gas cushion as a load and support instead of the usual spring
substantially as hereinbefore set forth.
6. The combination with the diaphragm 2; of the diaphragm chamber and super-
imposed air or gas chamber, substantially as herein before described with reference
to the drawings annexed.
7. The modified construction of apparatus substantially as herein before described
and shown at Figs. 3, 4 and 5 of the drawings annexed.
Dated this 10th day of November 1893.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.