AN IMPROVED ENGINE FOR PRODUCING MOTIVE POWER BY THE DILATATION OR EXPANSION OF CERTAIN FLUIDS OR GASES CAUSED BY THE APPLICATION OF CALORIC
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
DUNN, of New York, but now residing at the London Coffee House, Ludgate
Hill, in the City of London, Master Mariner, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Twenty-sixth day of
December, One thousand eight hundred and fifty, in the fourteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Edward Dunn, my exors, adññiors, and assigns, Her especial license, full
power, sole privilege and authority, that I, the said Edward Dunn, my
exors, adñiors, and assigns, or such others as I, the said Edward Dunn,
my exors, adiñors, or assigns, should at any time agree with, and no
others, from time to time and at all times during the term of years therein
expressed, should and lawfully might make, use, exercise, and vend, within
England, Wales, and the Town of Berwick-upon-Tweed, the Invention of
"AN IMPROVED ENGINE FOR PRODUCING MOTIVE POWER BY THE DILATATION OR
EXPANSION OF CERTAIN FLUIDS OR GASES CAUSED BY THE APPLICATION OF CALORIC"
(communicated to me from abroad); in which said Letters Patent is con-
tained a proviso that I, the said Edward Dunn, shall cause a particular
description of the nature of the said Invention, and in what manner the same
is to be performed, by an instrument in writing under my band and seal, to
be inrolled in Her Majesty's High Court of Chancery within six calendar

page_text: monthis next and immediately after the date of the said in part recited Letters
Patent, as in and by the same, reference being thereunto had, will more fully
and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Edward Dunn, do hereby declare that the nature of the said Invention, and
the manner in which the same is to be performed, are fully described and
ascertained in and by the following statement thereof, reference being had to
the Drawings hereunto annexed, and to the figures and letters marked thereon,
that is to say:-
The Invention consists in producing motive power by the application of
caloric to atmospheric air, or other permanent gases or fluids susceptible of
considerable expansion by the increase of temperature; the mode of applying
the caloric being such that, after having caused the expansion or dilatation
which produces the motive power, the caloric is transferred to certain metallic
substances, and again re-transferred from these substances to the acting medium
at certain intervals, or at euch successive stroke of the motive engine; the
principal supply of caloric being thereby rendered independent of combustion
or consumption of fuel. Accordingly, whilst in the steam engine the caloric is
constantly wasted by being passed into the condenser, or by being carried off
into the atmosphere, in the improved engine the caloric is employed over
and over again, enabling me to dispense with the employment of combustibles
excepting for the purposes of restoring the heat lost by the expansion of the
acting medium and that lost by radiation, also for the purpose of making
good the small deficiency unavoidable in the transfer of the caloric.
Having thus stated the object and general character, I will now proceed to
describe the structure of the improved engine for producing motive power,
reference being had to the Drawing. Figures 1 and 2 represent longitudinal
sections of the engines, both being alike in all essential points, differing only
in part of the detail as will be clearly seen by the following description.
I will first describe Figure 1. A and B are two cylinders of unequal
diameter, accurately bored and provided with pistons a, and b, the latter having
air-tight metallic packing rings inserted at their circumferences. I call A the
supply cylinder, and B the working cylinder; a', piston rod attached to the piston
a, working through a stuffing box in the cover of the supply cylinder. C, is a
cylinder with a spherical bottom attached to the working cylinder at c, c: I
callthis vessel the expansion heater. D, D, rods or braces, connecting together
the supply piston a, and the working piston b; E, is a self-acting valve, opening
inwards to the supply cylinder; F, a similar valve, opening outwards from said
cylinder, and contained within the valve box f; G is a cylindrical vessel,

page_text: which I call the receiver, connected to the valve box f, by means of the pipe g;
H, a cylindrical vessel, with an inverted spherical bottom: 1 call this vessel
the heater; J, a conical valve, supported by the valve stem j, and working in the
valve chamber J, which chamber also forms a communication between the
expansion heater C and heater EI, by means of the passage h; K is another
conical valve, supported by the hollow valve stem k, and contained within the
valve chamber ; Land M, two vessels of cubical form, filled to their utmost
capacity, excepting small spaces at top and bottom, with discs of wire net or
straight wires closely packed, or with other small metallic substances or mineral
substances, such as asbestos, so arranged as to have minute channels running
up and down: I call these vessels L and M, with their contents, regenera-
tors. 1, l, m, m, pipes, forming a direct communication between the receiver G
and the heater H, through the regenerators; N, N, two ordinary slide valves,
arranged to form alternate communications between the pipes 1, 1, and m, m,
and the exhaust chambers O and 1', on the principle of the valves of ordinary
bigh-pressure steam engines; n, n, valve stems working through stuffing
boxes n', n; p, pipe communicating between the valve chamber k¹ and
exhaust chamber P; o, pipe leading from exhaust chamber 0; Q, pipo
leading into the receiver G, provided with a stop cock 7; R, R, fire places for
heating the vessels H and C; r, r, r, r, flues leading from said fire places and
terminating at ; S, a cylindrical vessel attached to the working piston b,
having a spherical bottom corresponding to the expansion vessel C. This
vessel S, which I call the heat-intercepting vessel, is to be filled with fire-clay
at the bottom, and ashes, charcoal, or other non-conducting substances towards
the top, its object being to prevent any intense or injurious heat from reaching
the working piston and cylinder; T, T, brickwork, or other fire-proof material,
surrounding the fire places and heaters.
I now proceed to describe Figure 2. All corresponding parts in this Figure
are marked by similar letters of reference as in Figure 1. It will, however,
be well briefly to repeat the description of the same. A, supply cylinder;
a, supply piston; B, working cylinder; b, working piston; C, expansion
heater; c, junction of working cylinder and expansion heater; D, rods con-
necting the supply and working pistons; E, inlet valve of supply cylinder;
e. valve chamber of the same; F, outlet valve of supply cylinder, and f, its
chamber; G, receiver; g, pipe connecting the same to outlet valve chamber f;
L, regenerator; 1, passage between the same and the receiver; passage
between the regenerator and the expansion heater; N' slide valve; n, stem
or spindle for working the same; O, exhaust chamber under the slide
valve; o', outlet pipe; Q, pipe leading into receiver; q, stop cock in the same;

page_text: R, fire place; r, 1, 1, 1, flues leading from said fire place; 1, exit of said flues;
T, brickwork surrounding the fire place and flues; U, rock shaft supported
at both ends by appropriate pillar blocks u; w' crank lever or arm attached
to the said rock shaft; u", link connecting said arm to the working piston b;
V, another crank lever or arm attached the extreme end of the rock shaft;
æ, crank shaft or axle having a crank Y firmly attached; v, connecting rod
connecting the arm V to the crank pin y of crank Y; y', pillar blocks
supporting the crank shaft æ; Z, Z, represent the circumference of a fly wheel,
paddle wheel, propeller, or other rotary instrument to be worked by the
enginc.
Figure 3 represents a sectional plan of the Figure 1, and Figure 4 a sec-
tional plan of Figure 2.
Before describing the operation of the improved engine, it will be proper to
observe that the piston rod a' only receives and transmits the differential force
of the piston b, viz., the excess of its acting force over the reacting force of
piston a. It will also be proper to observe that this differential force imparted
to said piston rod may be communicated to machinery by any of the ordinary
means, such as links, connecting rods, and cranks, or it may be transmitted
directly for such purposes as pumping or blowing. I have further to observe
that the conical valves K and J may be worked by any of the ordinary means,
such as eccentrics or cams, provided the means adopted be so arranged that
the valve K will commence to open the instant that the piston b arrives at
the full up-stroke, and be again closed the instant the piston arrives at full
down-stroke, whilst the valve J is made to open at the same moment and to
close shortly before or at the termination of the up-stroke. In like manucr
the slide valve N is to open and close as the piston 6 arrives respectively at
its up and down stroke, similar to the slide valve of an ordinary high-pressure
engine. It will be seen that the link u", like the piston rod a', only transmits
the differential or useful force of the piston b.
Having thus described the construction of the engine, I will now proceed to
describe the manner in which the same is to be put in operation, reference
being first had to Figure 1. Before starting, fuel is put into the fire places
R, R, and ignited, a slow combustion being kept up until the heaters and
lower parts of the regenerators shall have been brought to a temperature of
about five hundred degrees. By means of a hand pump or other similar means
atmospheric air is then to be forced into the receiver G through the pipe Q
until there is an internal pressure of some eight or ten pounds to the square
inch. The valve J is then to be opened as shown in the Drawing; the pressure
entering under the piston 6 will cause the same to move upwards, and the air

page_text: contained in A will be forced through the valve F into the receiver. The slide
valves N, N, being, by means of the two stems n, n, previously so placed that
the passages 7, 7, are open, the air from the receiver will pass through the wires
in L into the henter H, and further into C, the temperature of the air
augmenting and its volume increasing as it passes through the heated wires
and heaters. The smaller volume forced from A will, in consequence thereof,
suffice to fill the larger space in C. Before the piston arrives at the top
stroke of the valve J will be closed, and at the termination of the stroke the
valve K will be opened; the pressure from below being thus removed, the
piston will descend, and the heated air in C will pass through k, p, P, and 'm,
into the regenerator M, and in its passage through the numerous small spaces
or cells formed between the wires part with the caloric, gradually falling in
temperature until it passes off at o' nearly deprived of all its caloric. The
commencement of the descent of the piston a will cause the valve F to close
and the valve E to open, by which a fresh charge of atmospheric air is taken
into the cylinder A. At the termination of the full down-stroke the valve K
is closed and the valve J again opened, and thus a continued reciprocating
motion kept up. It will be evident that after a certain number of strokes the
temperature of the wires or other matter contained in the regenerators will
change, that of M will become gradually increased, and that of L diminished.
The position of the slide valves N, N, should therefore be reversed at the
termination of every fifty strokes of the engine, more or less, which be
effected either by hand or by a suitable connection to the engine. The position
being by either of these means accordingly reversed to that represented in the
Drawing, the heated air or other medium passing off from C will now pass
through the partially cooled wires in L, whilst the cold medium from the
receiver will pass through the heated wires of M, and on entering H will have
attained nearly the desired working temperature. In this manner the re-
generators will alternately take up and give out caloric, whereby the circulating
medium will principally become heated, independently of any combustion after
the engine shall have been once put in motion.
may
Having thus with special reference to Figure 1 described the manner of
putting the improved engine into operation, I have now to notice that the said
engine, as represented in Figure 2, is operated precisely in the same manner,
excepting that the regenerator is arranged in a single vessel, and that the metallic
substances therein take up the caloric from the circulating medium that leaves
the working cylinder or vessel C, and returns the same to the circulating
medium that enters the working cylinder at each stroke of the engine, instead
of transferring and re-transferring the caloric at intervals as shewn in Figure 1.

page_text: b
The manner in which the differential or useful upward force of the working
piston (Figure 2) in conjunction with its descending power caused by gravity
are made to impart rotary movement to the crank shaft a becomes self-evident
on examining the disposition of the working gear of the engine, as shewn in
the Drawing. It is particularly worthy of notice that the relative diameter of
the supply and working cylinder will depend on the expansibility of the acting
medium employed; thus, in using atmospheric air or other permanent gases,
the difference of the area of the pistons may be nearly as two to one, whilst, in
using fluids such as oils which dilate but slightly, the difference of area should
not much exceed one tenth. I have next to notice, that in employing any
other medium than atmospheric air it becomes indispensable to connect the
outlet pipe O¹ and the valve box e of the outlet valve E, as indicated by dotted
lines in both Figures, these dotted lines representing the requisite connecting
pipe. The escaping air or fluid at 0¹ will, when such a connecting pipe has
been applied, furnish the supply cylinder, independently of other external
communication, and the acting medium will perform a continuous circuit
through the machine under this arrangement, the operation being in other
respects as before described. It is evident that the several parts composing
the improved engine may be arranged in various ways, and that the external
form thereof may be greatly changed, whilst its principle of operation remains
substantially as I have ascertained and described. It is also evident that the
working cylinder may be placed horizontally or otherwise, and that it may be
made double-acting, and that a heat-intercepting vessel may be applied at each
end of the working piston, as also an expansion heater at each end of the
working cylinder. I do not therefore confine myself to the exact form rc-
presented in the Drawing, but I claim as the Invention the substantial features
of the devices I have described as new, and by which I secure great and
beneficial results. And particularly 1 claim as the Invention:-
First. I claim the structure which I call the regenerator, by which I effect
a transfer of the caloric contained in the air or other circulating medium that
passes off from the working cylinder to a series of discs of wire net or to
other minute metallic or mineral substances for the purpose of being again
re-transferred to the air or other circulating medium that enters the working
cylinder, whether said structure be so arranged that the metallic or mineral
substances are made to take up and again return the caloric at each successive
stroke of the working piston as in Figure 2, or whether it is so arranged that
the transfer and re-transfer of the caloric takes place at intervals as in Figure 1,
or whether said structure is arranged in any other manner for the purpose of
accomplishing substantially the purposes herein-before mentioned.

page_text: Second. I claim the combination of the expansion heater with the working
cylinder, by which the fall of temperature consequent upon the expansion of
the air or other circulating medium during the upward movement of the
working piston becomes restored, and by which also the force of said piston
becomes augmented beyond what it would be if the accession of caloric effected
by the expansion heater did not take place.
Third. I claim the heat-intercepting vessel attached to the working piston,
by which any injuriously high temperature is prevented from reaching the
packing of said piston, and by which also the very desirable end is attained of
presenting at all times surfaces of uniform high temperature to the acting
medium under the working piston.
Fourth. I claim the inverted position and open ends of the working and
supply cylinders as represented in the Drawing.
Fifth. I claim the direct attachments of the working and supply pistons, by
which not only the acting and reacting forces may be uniformly distributed
over the area of each piston, but by which also the entire differential power of
the working piston is rendered available, less only the friction of the packings.
In witness whereof, I, the said Edward Dunn, have hereunto set my
band and seal, this Twelfth day of June, One thousand eight hundred