IMPROVEMENTS IN CALORIO OR HEATED AIR ENGINES
Year: 1863

page_text: LETTERS PATENT to Walter Davis Richards, of the City of Boston, in the
United States of America, for the Invention of "IMPROVEMENTS IN CALORIO
OR HEATED AIR ENGINES," A communication from Heury Messer, residing
at Roxbury, in the County of Norfolk, and State of Massachusetts,
and United States of America.
COMPLETE SPECIFICATION filed by the said Walter Davis Richards at
the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 11th November 1863, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
DAVIS RICHARDS, of the City of Boston, in the United States of America,
send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
CALORIC OR HEATED AIR ENGINES," and have petitioned Her Majesty to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that the same
is a communication. from Henry Messer, a person resident at Roxbury,
in the County of Norfolk, and State of Massachusetts, and United
States of America.
NOW KNOW YE, that I, the said Walter Davis Richards, do hereby
ED 971

page_text: declare that the following Complete Specification under my hand and
seal fully describes and ascertains the nature of the said Invention, and
in what manner the same is to be performed, in and by the following
statement, reference being had to the accompanying Drawings, and to
the letters and figures marked thereon, that is to say:-
My Invention relates to several improvements in caloric or heated air
engines, which improvements are intended to effectually do away with
the many objections to those engines known as Stirlings and Erricson's
caloric or heated air engines.
One of my improvements consists in making the walls of the furnace
hollow, with projections or reveals into the space for the purpose of in-
creasing the heated surface when these projections are tubular or take
the form of depressions from the inner boundary of the furnace, and
when the parts are arranged so as to leave spaces in the walls connected
with each other, as to compel all the air entering these spaces to come
into contact with the increased surface caused by these projections.
Also in a new method of regulating the speed of such engines by
forming a communication between the air pump and the cylinder in
such a manner that when the engine moves above its normal rate of
speed, the regulator by its action on a valve in the passage between the
air pump and the hot air cylinder operates to let all or a portion of
the cold air into the cylinder direct from the air pump, thus supplying
the space left by the movement of the engine piston with cold air, in-
stead of wasting generated caloric by allowing the heated air to blow off
while its entrance into the engine cylinder is throttled (as is usual in
other engines), and instead also of allowing the compressed air to be
blown off, which is often done in other engines of like character.
Also in arranging of a single valve in the passage between the furnace
and air pump; that by a change in the position of the valve the supply
of air from the pump may be made to pass entirely through the grate
and fuel, or entirely into the furnace above the fuel, first passing to be
heated through the hollow spaces (before mentioned) in the walls of the
furnace, or partially in both ways, as may be required.
Also in the arrangement within one common passage of one valve
connected with the regulator for the purposes before referred to, and
of another valve used, as before mentioned, to determine in what pro-
portion air shall be supplied under or above the fuel.
Also another important improvement in this class of engines (in
construction) is to elongate the piston down into the lower part of the
cylinder (which may be termed a trunk piston), for the purpose of
obtaining a longer connecting rod, as also in the peculiar conformation

page_text: of that part of the piston where the packing is seated, whereby the pis-
ton and cylinder may be lubricated with steam or water.
Also in the peculiar arrangement by which direct conduction of heat
from the lower portion of the cylinder to the upper portion is checked,
keeping the upper portion cool where the packing works, and the lower
portion hot, so as not to diminish the temperature and consequent pres-
sure of the impelling medium.
Also in so arranging and combining the valve seats of chambers and
passages with the lower portion of the cylinder, that they form an
integral portion thereof, avoiding the necessity heretofore existing of
separate parts; access can be had to the valves in the most convenient
manner.
Other and important improvements in caloric or heated air engines
consists in attaching the pump cylinder to the working piston of the
air engine, and the employment of a stationary compressing piston; the
great object being to employ the weight of the said cylinder to aid the
working piston in its downward or return stroke (the engine being
single acting), and the air only operating to produce the upward stroke;
there is also a certain arrangement of the induction and eduction valves
and valve chest of the working cylinder.
Another improvement in caloric or heated air engines is in the mode
of regulating them to prevent excess of speed, and is effected by so con-
necting the regulator with the valve that it opens the valve and reduces
the impelling pressure by permitting more or less of the expanded air
and gases to escape past the said valve. When the speed of the engine
is reduced, the regulator again operates to close the valve, thus pre-
venting further escape of the expanded air and gases; this arrangement,
while it measurably answers its purpose, is defective inasmuch as a por-
tion of the generated caloric is lost; it also affords no means of bringing
the engine to its speed again, should it fall below in consequence of
having to perform an increase of work.
The great object of my Invention is to regulate heated air engines
without waste of the generated caloric, and in such a manner that the
act of reducing of excessive speed shall afford the means of increased
diminished speed.
Another important improvement in caloric or heated air engines is in
the case of steam in connection and combination with such engines, the
steam being obtained from any ordinary steam boiler.
Alsó in the introduction of steam into the furnace of caloric or heated
air engines, bringing the steam into immediate contact with the incan-
descent fuel for the purpose of decomposing it into its original elements,

page_text: mingling the steam with the compressed heated air and gasseous products
of combustion within the furnace.
Also in utilizing the exhaust heat of a caloric or heated air engine by
passing the exhausted air through any ordinary steam boiler.
Chapter 1st. In order that these several improvements in caloric
or heated air engines may be more fully understood, I shall now proceed
more particularly to describe the same, and for that purpose I shall refer
to the several Figures in the Sheets of Drawings hereunto annexed.
Figure 1, Sheet 1, is a side elevation of a heated air engine; Figure 2,
a vertical cross section taken in the line z, z, seen in Figs. 1 and 3, and
looking toward the furnace; Figure 3 is a horizontal section taken in
the line y, y, seen in Figs. 1 and 2; Figures 4, 5, and 6, are respectively
elevations and a plan of the lower part of the cylinder with valve, cham-
bers, seats, and passages; Figure 7 is a vertical section taken through
the furnace; Figure 8 is an elevation of the whole of the piston.
A is a casing or base around the furnace, and enclosing also the lower
portion b of the cylinder, all of the space in the base unoccupied by
these parts, and by the necessary passages, conduits, or pipes, being
filled with non-conducting material.
The furnace, which is represented in Figs. 3 and 7, has a grate made
of two plates of iron kept as under and held into contact by tubes, these
forming the spaces through which air forced under the grate passes to
and through the fuel supporting combustion. The sides and top of the
furnace are made thick, but hollow, with depressions from the inside
of the furnace extending into the hollow space of the walls; these de-
pressions or tubes, closed at one end, are marked c, and the spaces in the
walls of the furnace are marked d. These spaces and the spaces between
the grate plates communicate with each other in such a way that when
air is forced between the plates forming the grate it will pass from
thence into the space in and up one of the furnace sides, from there
down the spaces in the ends, from there up the space in
the other side of the furnace, from which, through proper
openings, it debouches into the upper part of the furnace, and being
heated in its passage by contact with the extended surface over which
it has passed, it mingles with the heated air and other products of com-
bustion in the furnace, and with them becomes the impelling medium,
which, through a proper opening in the furnace and conduit, is con-
ducted to the opening e in b, which enters the chamber f of the inlet
valve.
In the construction of the air pump there is nothing novel, it being

page_text: worked direct from the main shaft and discharges into the passage g,
in which are located the two way valves h and i. The valve h is con-
nected in any well-known manner (not shewn) with the engine, regu-
lator, or governor (also not shewn), which so acts as to keep the valve in
the position shewn in the Drawings so long as the engine runs at or
below its normal speed, thus letting air pass from the pump along the
passage g to the valve i, from whence its course will be described; but
when the engine runs above its proper speed the regulator or governor
changes the position of the valve h, so that the part of the passage g
leading towards is closed and free communication is established
between the pump and the engine cylinder through the pipe j, which
terminates in the inlet valve chambers f, and by the admission of cold
air into the engine cylinder from the pump the entrance of the impel-
ling medium from the furnace is in some degree checked and the speed
of the engine is lessened, which causes the governor or regulator to act
to the place of the valve h and the position, as shewn in Fig. 3. The air,
being in this way prevented from flowing along j, proceeds through g
to the valve i, which is a distributing valve, and acts by its position to
cause the air from the pump to flow through the pipe k to the space under
the grate, from whence it passes through the tubular openings of the
grate up through the fuel to urge combustion; or the valve i may be so
turned by hand as to shut off the air from passing through k and to
compel it to enter the pipe 1, by which it is discharged into the space
in the walls of the furnace, and thence by the route previously described
(or any other equivalent thereto) it escapes into the combustion cham-
ber; or the valve i may be so turned by hand as to leave the passages k
and partly open, so that part of the air may be discharged below the
grate and part above it into the furnace.
In some heated-air engines heretofore constructed the upper or packed
part of the piston which fills the upper bored or finished part m of the
cylinder is substantially made of cast iron or otherwise suitably formed
so that the piston or connecting rods can be so firmly connected as to
withstand the strain brought upon them, and attached to the bottom
of this part the piston, it being made of lighth sheet iron or other
metal, and usually filled with some suitable non-conducting substance,
this part nearly filling the lower part b of the cylinder when the piston
is at the end of its down stroke. Now, in order to lessen the height of
the engine to render it more compact and to increase the length of the
connecting rod, I extend the upper rigid cast portion of my piston down-
ward, so there is but little space left between it and the thin casing,
which makes the outside of the piston extension.

page_text: In Figure 2 n shews the upper part of the packed piston, but instead
of having a plate or disc at its bottom to which the connecting rod is
jointed, there is an extension o protruding downward, within and to
the bottom of which the connecting rod is journalled. This extension o
is surrounded by a thin casing p, and the space between o and p may
be filled by any suitable non-conductor. The upper part n of the piston
is provided with a metallic packing ring or rings, which may be made in
the manner of any known metallic packing for cylinders. In the rear
of this packing there is a groove formed in the piston at 9 which, by
means of a rubber pipe or of a metallic pipe with telescopic slides fixed
to the passage at r, it is supplied with water or steam, which, finding
its way through apertures formed in the packing rings, lubricates the
surface of the piston and also of the cylinder as the piston is moved
within it. As the lower part of the cylinder receives most heat in the
action of the engine, and as the upper part only has the piston fitted
tightly therein, it is necessary to keep the part b as cold as possible, and
to that end I prevent in a great measure transmission of heat by conduc-
tion from the lower to the upper part of the cylinder as follows:-
Between the part 6 and its base flange a curvature s is introduced in
the casing, as shewn in Figures 1 and 2, so that within the space enclosed
by m at the curvature s, and on the plate t covering the bed or case a,
there is afforded room for the interposition of any known material as a
non-conductor. This and the fact that the top flange of the lower part
of the cylinder extends outward under the plate t only as far as the
space for the non-conductor, practically limits to the minimum amount
of conduction of heat from 6 to m. To avoid the troubles arising from
joints liable to leak, and from expansion and contraction consequent on
change of temperature, I construct the valve chambers f and v, valve
seats, induction and eduction pipes or passages w and x, integral with
the lower part 6 of the cylinder, with the chambers f and open at the
end of the part b and terminating flush with or in the same plane with
the flange of b, so that by facing off the flanges of 6 and m and both sur-
faces of t the joints between these parts can be cheaply and well made,
while at the same time b can expand freely downward (the non-conduct-
ing filling being so arranged as to permit this) and m upwards; the
valves and seats can be easily reached for repairs by the removal of the
covers u. By arranging dampers or valves (so that at will) the heated
air can be shut off in the hollow walls of the furnace from entering the
combustion chamber for the purpose of supplying the engine with an
impelling medium in the form of the heated air from the said hollow
walls whenever it is necessary to open the combustion chamber to sup-

page_text: ply fuel upon the grate, so that the engine can be kept in motion while
so supplying the fuel by means of the heat stored up in the furnace
walls, and thus render unnecessary the valvular arrangement now in
use for supplying fuel to air-tight fire-boxes when the engine is in
motion. The valves can be worked by any of the well-known methods
for moving of valves.
Chapter 2, Sheet 2.-Fig. 1 is a vertical section of a caloric or heated
air engine, with other of my improvements; Fig. 2 is a plan of the same
partly in section; Fig. 3 is a front view of the interior of the chest which
contains the induction and eduction valves of the working cylinder.
Similar letters of reference indicate corresponding parts in the several
Figures.
A is the working cylinder arranged in an upright position, having its
lower part inserted into and surrounded by an air heating chamber B,
which also surrounds and incloses the furnace C; this cylinder is open at
the top. D is the working piston fitted to the diameter of the cylinder
A, provided with suitable packing, and having secured to its upper side
and concentric with it the pump cylinder P. The piston D is made
hollow, and the cavity a in its interior has free communication with the
interior of the pump cylinder P, provided by openings S, S', shewn in
Figure 1. The said piston is provided with a valve e at the top (open-
ing downward and inward from the atmosphere to its cavity a. E is
the pump piston, having for its piston rod a portion of the pipe F,
which is connected with the air heating chamber B to supply air thereto.
This pipe is fitted to the tight cover of the pump cylinder with a stuffing
box G. This cover is furnished with a valve b opening downwards or
inward from the atmosphere. The stationary pump piston E is hollow,
and its internal cavity is always in communication with the pipe F.
This piston has an inverted valve c in its top surface opening downward
and into the internal cavity of the piston, the valve d in its bottom sur-
face opening upward, and also into the internal cavity of the piston.
H is the valve chest containing the induction valve I for the induction
of the compressed and heated air from the furnace C into the lower
part of the working cylinder A, and the eduction valve J for the escape
of the exhausted air from the cylinder to the atmosphere. The air
from the furnace is conducted to the valve chest by a pipe M, and the
exhausted air leaves the valve chest by a pipe J'. The valves I and J
may be operated on by any suitable mechanism, such as is employed
for working the induction and eduction valves of steam engines. By
the attachment of the pump cylinder to the working piston the weight
of the cylinder is made to assist in producing the downward stroke of

page_text: the piston, and by that means I succeed in obtaining in air engines a
more uniform developement of power throughout the revolution of the
shaft. The operation of the two pistons and the several valves applied
in connection with them is as follows:-In the downward movement
of the working piston D the valves b and d are closed and c and e are
open, and the air with which the part of the pump cylinder above its
piston E has been previously filled is compressed and forced through
the valve c, the pump piston E, and pipe F into the chamber B, and
thence through the openings m, m, into the furnace c, while the pump
cylinder is filled below the piston with fresh air entering through the
valve e.
In the upward movement of the piston D, produced by the expansion
of heated air admitted to the cylinder A from the furnace through the
pipe M and valve I, the valves b and d are open and c and e closed, as
represented in Fig. 1, and the air with which the pump cylinder E has
been filled below its piston P is forced through the valve d, the piston
E, and pipe F into the chamber B and furnace C, while fresh air enters
the pump cylinder E above its piston P through the valve b. The
pump is thus double acting, operating both in the upward and down-
ward stroke of the working piston D, which may be made to produce a
rotary movement of the crank shaft L by any suitable system of con-
nections. Figure 1 represents the connection with the crank as being
made by a forked rocking beam N and rods O and V. The arrange-
ment of the valve chest H and valves I, J, to afford convenience for
getting at the valves is illustrated in Figs. 2 and 3. These valves are
what is termed puppet valves, and the chest is divided into four com-
partments i, i¹, and j, j', the compartment i having the induction pipe
M attached, and being always in communication with the furnace or
air heating chamber; the compartment j having the exhaust pipe J¹
attached, and the two lower compartments i' and j' both communicating
with the cylinder. The induction valve I is placed between the com-
partments and 2, and the eduction valve J between the compart-
ments j and j'. The chest H is situated opposite to the opening C pro-
vided in the cylinder casing or air heating chamber B of the engine,
such opening being fitted with a tight cover t, which is only removed
when it is desired to examine the valves. The chest is also constructed
with an open front fitted with a light moveable cover u, such cover
being opposite to the opening v. By taking off the two covers t and u
the whole of the interior of the valve chest is exposed, as shewn in Fig.
3. Instead of having the air circulate around the fire-box, it may be
prevented from circulating over the sides by filling the space between
it and the outer casing with any known non-conductor.

page_text: Chapter 3. Another part of my improvements in the caloric or
heated air engines is to regulate the movement of the engine without
waste of generated caloric, and in such a manner that the act of reducing
excessive speed shall afford the means of increasing diminished speed.
This I accomplish as follows, reference being had to Figures 4, 5, 6,
and 7, Sheet 2.
Fig. 4 is a plan of so much of a heated air engine as is necessary to
illustrate that part of my further improvements; Fig. 5 is a side cleva-
tion of the same; Fig. 6 is a vertical section taken in the line z, z, seen
in Fig. 4; Fig. 7 is a section taken through the regulator in the plane
of the line a, a, seen in Fig. 5.
a represents the base of the engine, which supports the cylinder b, in
which base is contained the furnace; c is the main shaft. The regulator
or governor is supported on an horizontal spindle by the stud d fixed on
to the base a. The balls e, e, rotate in a vertical plane, so that the
changes in the position of the balls e, e, occasion the variation either of
increased or decreased speed, causes a rectilinear movement of the
piece f in the direction of the axis of the spindle g. There are two
cylinders secured to the base, one a mere reservoir marked h, provided
with a closely-fitted piston i, which is capable of moving vertically
under the influence of a spring j. The cylinder is also intended to be
provided with a safety valve (which is not shewn) so arranged as to
save the lower end of the cylinder from excessive pressure. The piston
rod is made hollow for the purpose of placing thereupon a spring
safety valve. The other cylinder is a common force pump arranged
with induction and eduction valves, which operate when the piston m
is reciprocated to force air at each stroke of the pump into the pipe 7.
This pipe communicates between the reservoir and the force pump,
the communication being controlled by a valve, which, according to its
position, admits of the air being forced by the pump into the reservoir.
or else discharged through the aperture o; communicating between the
lower part of the reservoir h, and the furnace containing chamber a is
a pipe u, in which is a valve which permits or prevents communication
between h and a. To suit the arrangement of the mechanism the valves
int and u are of the rotary plug kind, and are worked by rotation of
the spindles n' and ', these having attached to their upper ends levers
or rocking arms n" and p", these spindles being supported by a stand g.
On the ends of n" and 2" are pins which engage in grooves in /, so that
it will be plain that reciprocations off will cause partial rotation of the
valves n and p. As a matter of detail in practical operation the grooves
in are made a little wider than the diameter of the pins in n" and p",

page_text: and springs are so applied to n and p, or to n" and p", as to keep the
pins in the centre of the said grooves when the regulator and the parts
are in their normal position, and the engine running at its proper speed,
which normal position is when the valve u lets the air from the pump
freely out of the aperture o, and when the valve p closes communication
between and a.
of
The operation and effect of this part of my Invention in caloric or
heated air engines is as follows:-When the engine is running at proper
speed the force pump discharges the air which is forced by it out of the
aperture o, but if the speed of the engine is increased, then the regu-
lator or governor balls fly outward, the effect of which is to move the
valves n and p; n is moved so as to close the aperture o, and the motion
?' does not open any communication between and a. Thus it will
be readily seen that the pump now puts an additional load on the engine
by causing it to labor in compressing air within h which tends to reduce
the speed of the engine to its normal rate when the aperture o is open,
and when communication is not established between h and a. But if
now on account of an additional load put on the engine its speed is
reduced below the normal rate, this causes a motion of which opens
the aperture o and the communication between the reservoirs h and a,
thus supplying a with compressed air to urge the fire, and thence,
expanded by heat, increasing the impelling pressure, and again to bring
the engine up to her speed. By applying handles to the spindles n'
and p', and by loosening the set screws s, s, on the n" and ", the
engine can be made just before stopping, and irrespective of its rate of
speed, to fill the reservoir with compressed air, which, after stopping
the engine, will start it again by simply admitting this compressed air
into a.
Chapter 4. Other important improvements in caloric or heated air
engines is in the use of steam in connection with heated air or gases.
A regulator of an ordinary construction is attached to the engine and
connected with a valve in the steam pipe leading from an ordinary
steam boiler to the engine, and alsó attached with a valve communicating
with the air chamber of the engine. When the speed of the engine is
increased the valve in the steam pipe is closed. If that does not check
the speed of the engine sufficiently the valve in the engine is opened,
allowing the air to escape, thereby reducing the pressure in the engine
sufficiently to reduce the speed. In the meantime the pressure in the
boiler is increasing much above the pressure in the engine. It will be
seen that when the engine by an increased load is brought below the
proper speed, the action will be the reverse, giving the benefit of the

page_text: power stored in the boiler, enhancing the power of the engine, and
giving the same result as that obtained in an ordinary steam engine.
I also introduce steam into the furnace of a heated air engine, in which
pressure is maintained when the steam is brought into immediate con-
tact with the incondescent fuel for the purpose of decomposing it into
its constituent gasses and mingling them with the compressed heated
air and gaseous products of combustion within the furnace. I also
utilize the exhaust heat of a caloric or heated air engine by passing the
exhausted air through any ordinary steam boiler by any of the well-
known mechanical means.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe that I do not confine myself to the
precise details or arrangements, as many variations may be made there-
from without deviating from the principles or main features of my said
Invention, but what I consider novel and original, and therefore claim
as of my Invention secured to me by the herein-before recited Letters
Patent, is,-
1stly, I claim the construction of the walls of the furnace in the man-
ner and for the purposes substantially described.
Also in checking the motion of a heated air engine piston by connect-
ing the air pump with the cylinder in such a manner that the whole or
a portion of the air condensed by the pump can pass into the cylinder
without detention on its passage for the purpose of being heated, and
by arranging the passages and valve with the engine regulator that by
the action thereof air may be admitted into the cylinder for the pur-
pose of checking the speed of its piston when running too rapidly.
2ndly, in the arrangement of the valve I with respect to the pump,
the space below the grate, and the spaces in the walls of the furnace,
substantially as and for the purposes specified.
3rdly, the arrangement in one passage of a valve operating to check
the speed of the engine piston, also with a valve operating to determine
in what proportion air shall be supplied to the furnace above or below
the fuel.
4thly, also the elongation downwards of that part of the piston to
which the connecting rod is attached and the application of that form
of trunk; also in the peculiar construction of perforated packing with
its grooves and channels in the rear of the perforations, as also the
means described to supply the said grooves with steam or water for
lubrication, as fully described.
5thly, also the arrangement and combination of parts by which con-

page_text: 9thly, also the new arrangement of regulating caloric or heated air
engines in the manner fully set forth in this Chapter and shewn in the
Drawings annexed.
CLAIMS IN CHAPTER 4.
10thly, the use of steam in connection and combination with caloric
or heated air engines, regulated and controlled as fully described; also
the communication with the air chamber of the cylinder with regulating
valves, &c., as fully set forth.
11thly, also the introduction of steam into the furnace of caloric or
heated air engines, in the manner and purposes described.
12thly, also in utilizing the exhaust heat of a caloric or heated air
engine by passing the exhausted air through an ordinary steam boiler,
all of which is fully set forth in Chapter 4.
In witness whereof, I, the said Walter Davis Richards, have here-
unto set my hand and seal, the Fifth day of November, in the
year of our Lord, One thousand eight hundred and sixty-three.
WALTER D. RICHARDS. (L.S.).