AN IMPROVED AIR ENGINE SO ARRANGED THAT IT MAY BE DRIVEN EXCLUSIVELY BY THE EXPANSION OF AIR, OR THE HEATED AIR MAY PASS THROUGH A STEAM GENERATOR, AND THE STEAM BO GENERATED BE USED IN ADDITION TO THE EXPANDED AIR TO ENHANCE THE PRESSURE UPON THE PISTON AND THUS ADD TO THE POWER OF THE ENGINE
Year: 1867

page_text: LETTERS PATENT to Philander Shaw, of Boston, in the County of
Suffolk, and State of Massachusetts, one of the United States of America,
now of No. 8, Southampton Buildings, Chancery Lane, in the County of
Middlesex, for the Invention of "AN IMPROVED AIR ENGINE SO ARRANGED
THAT IT MAY BE DRIVEN EXCLUSIVELY BY THE EXPANSION OF AIR, OR THE
HEATED AIR MAY PASS THROUGH A STEAM GENERATOR, AND THE STEAM BO
GENERATED BE USED IN ADDITION TO THE EXPANDED AIR TO ENHANCE THE
PRESSURE UPON THE PISTON AND THUS ADD TO THE POWER OF THE
ENGINE."
Sealed the 17th September 1867, and dated the 29th March 1867.
PROVISIONAL SPECIFICATION left by the said Philander Shaw at the
Office of the Commissioners of Patents, with his Petition, on the
29th March 1867.
I, PHILANDER SHAW, of Boston, in the County of Suffolk, and State of
Massachusetts, one of the United States of America, now of No. 8, South-
ampton Buildings, Chancery Lane, in the County of Middlesex, do hereby
declare the nature of the said Invention for "AN IMPROVED AIR ENGINE SO
ARRANGED THAT IT MAY BE DRIVEN EXCLUSIVELY BY THE EXPANSION OF AIR, OR THE
HEATED AIR MAY PASS THROUGH A STEAM GENERATOR, AND THE STEAM SO GENE-
RATED BE USED IN ADDITION TO THE EXPANDED AIR TO ENHANCE THE PRESSURE

page_text: UPON THE PISTON AND THUS ADD TO THE POWER OF THE ENGINE," to be as
follows:-
The said Invention relates to improvements in the machine described in the
Specification of Letters Patent granted to me for "Improvements in Hot Air
Engines," bearing date the Nineteenth day of July, in the year of our Lord
One thousand eight hundred and sixty-one, No. 1818.
The said Invention consists chiefly, first, in so constructing the inlet valve
and its adjuncts that a blast of cool air is sent upon the valve at each stroke
of the engine.
Second, attaching to the stem of the puppet valve, which admits cold air
into the air pump, a disc working in an air cylinder, the object of the said
dise being to prevent vibration or fluttering of the valve.
Third, in the mode of constructing the lining of the furnace so as to leave
a space between the brick lining and metallic casing of the furnace.
Fourth, in combining a vacuum valve with the working cylinder of an air
engine.
Fifth, in the peculiar mechanism for operating the lower or inner door or
swinging slide of the fuel feed box, this door turning upon an axis so that it
may swing around in its own plane. The disc forming the main portion of
the inlet valve, which is exposed to great heat, is constructed with a cylinder
extending upwards, so that the valve as a whole forms a cylindrical vessel
open at the top; into this valve a pipe from the air pump enters and conveys
a blast of cool air at each stroke of the engine; this cool air after effecting its
purpose, that is, lowering the temperature of the valve, is free to flow out of
the valve into the passage leading into the working cylinder. A flat disc is
attached to the stem of the puppet valve which admits cold air into the air
pump; the said disc plays as a loose fitting piston head in a cylinder located
immediately over the puppet valve; the upper end of this cylinder being air-
tight. As this disc fits the said cylinder quite closely it cannot be moved up
and down very rapidly from the fact that time must be allowed for the air to
escape from the chamber if the disc is moving upwards, or to enter the
chamber if the disc is moving downwards, and as this disc is connected directly
to the valve no rapid vibration or fluttering of the valve can take place. The
fire-brick with which the furnace is lined is constructed with knobs or projec-
tions upon the backs so that an air space is left between the brick lining and
metallic casing of the furnace. Small metal tubes are provided to conduct
the heated exhaust air to the chimney; a portion of the caloric of this exhaust
air is absorbed by these metal tubes, and given off therefrom to the cool air
or water surrounding the same. When the furnace is used as an auxilliary

page_text: heater the cool air circulates around these tubes and passes thence through
the air space between the lining and casing into the ash-pit, and then into the
furnace. A vacuum valve is combined with each working cylinder of the
engine; the said valve is placed near the bottom of the cylinder, covering an
orifice which forms a communication between the open air and the cylinder.
The object of this valve is to allow air to flow in and prevent the vacuum
that would otherwise be formed while the engine is being started before a
working pressure is obtained. The bottom of the feed box for supplying the
furnace with fuel is provided with a sliding bottom or valve which turns on
an axis, and is operated by a swinging arm. This arm is formed with
teeth which gear with a pinion, the latter being furnished with a suitable
handle or lever for operating the same. By this arrangement the fire-box
may be replenished with fuel without reducing the pressure in the furnace.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Philander Shaw in the Great Seal Patent Office on the
21st September 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PHILANDER
SHAW, of Boston, in the County of Suffolk, and State of Massachusetts, one
of the United States of America, now of No. 8, Southampton Buildings,
Chancery Lane, in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of March, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirtieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Philander Shaw, Her special licence that, I, the said Philander Shaw, my
executors, administrators, and assigns, or such others as I, the said Philander
Shaw, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "AN IMPROVED AIR ENGINE SO
ARRANGED THAT IT MAY BE DRIVEN EXCLUSIVELY BY THE EXPANSION OF AIB, OR THE
HEATED AIR MAY PASS THROUGH A STEAM GENERATOR, AND THE STEAM SO
GENERATED BE USED IN ADDITION TO THE EXPANDED AIR TO ENHANCE THE
PRESSURE UPON THE PISTON AND THUS ADD TO THE POWER OF THE ENGINE," upon
the condition (amongst others) that I, the said Philander Shaw, my executors

page_text: or administrators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Philander Shaw, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Sheet of Drawings,
forming a part of this Specification :-
The said Invention relates to improvements in the machine described in the
Specification of Letters Patent granted to me for "Improvements in Hot Air.
Engines," bearing date the Nineteenth day of July, in the year of our Lord
One thousand eight hundred and sixty-one, No. 1818, and the said improve-
ments consist,―
First, in the peculiar construction and arrangement, as herein-after
described and further illustrated in the Drawings, of the inlet valve. This
valve being exposed to great heat is made in the form of a cylindrical vessel
into which a pipe conducts at each stroke of the engine a current of cool air,
which, effecting its purpose, that is, lowering the temperature of the valve, is
free to flow out upwards around the outside of the said pipe into the passage
leading into the working cylinder.
As this disc
Second, in attaching to the stem of the puppet valve herein-after described
a disc which plays as a loose fitting piston head in a chamber.
fits the cylinder in which it plays quite closely it cannot be moved up and
down very rapidly from the fact that time must be allowed for the air to
escape from the chamber if the disc is moving upwards, or to enter the
chamber if the disc is moving downwards, and as this disc is connected directly
to the valve no rapid vibration or fluttering of the valve can take place.
Third, in constructing the fire-brick herein-after described with knobs or
projections upon the backs, so that an air space is left between the brick
lining and the metallic casing of the furnace.
Fourth, in combining a vacuum valve with the working cylinder of an air
engine.
Fifth, in the peculiar mechanism herein-after described for operating the
lower or inuer door of the fuel feed box. This door turns upon an axis, the
turning being produced by operating a pinion, which meshes into a gear cut
upon the rear end of the door.

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 illustrates, partly in elevation and partly in vertical section through
one of the working cylinders, a hot air or caloric engine embodying my
Invention; Figure 2 is a vertical section through the fire-pot and other parts
of the said engine, showing also an elevation of one of the cylinders; Figure 3
is a vertical section through one of the cylinders and the fire-pot on the
line y, z, Figure 5; Figure 4 is a plan of the said engine; Figure 5 is a
horizontal section of the same; Figure 6 represents the steam generator in
elevation and part of the fire-box in section; Figure 7 is an enlarged view of
the pump inlet valve.
S, Figures 2 and 5, represents the furnace, Figure 2 showing it in elevation
and Figure 5 showing a horizontal section of it, and a plan of the grate J
These fire-bricks have pro-
representing an inside lining of fire-brick.
jections j,j, or knobs made on their outer side, as shown, which separates
them from the outside lining J', thus leaving an air space between the inner
and outer lining extending entirely around the furnace, through which the air
that enters the furnace above the grate flows. A', A¹, Figures 4 and 5, is an
air-tight casing extending entirely around the furnace, and with its top and
bottom forms the air-tight reservoir for compressed air, and includes within
itself the furnace, the inlet and outlet valves, and most of the tubes through
which most of the air flows. c, Figures 2, 4, and 5, represents the direct
draft or orifice for the escape of the products of combustion when the fire is
first built, but may be closed by means of a door or valve similar in construc-
tion to that shown for the fuel box H, Figure 4, when the fire is well started.
I, Figures 2, 4, and 5, represents the ash opening which leads directly under
the grate I; Figures 4 and 5 represents the fuel opening which leads directly
into the furnace; both the ash and fuel openings have doors that fit air-tight,
constructed similar to the door c of the fuel box H, Figure 2. H, Figures 2
and 4, represents a fuel receptacle from which the fuel is fed to the fire while
the engine is in action through the top of the furnace; this fuel box is
provided with an air-tight receiving door c¹, Figure 2, having a clamp a and
hand screws, so that it may be securely fastened. The bottom of the fuel
box H is provided with a sliding bottom or valve U, which is operated by the

page_text: swinging arm U', Figures 2 and 4. This swinging arm has a gear cut upon
its rear end, as shown in the Drawings, into which a pinion Pi works; this
pinion is operated by a lever h. By this arrangement, and by proper mani-
pulation, which will be understood by inspection of the Drawings, it is obvious
that the fire may be replenished with fresh fuel, while there is the requisite
pressure within the furnace to operate the engine without reducing this pressure.
I claim as new the peculiar construction of this fuel box. The furnace is
provided with an opening a, Figures 2, 5, and 6 above the grate, and with an
opening a¹, Figures 2 and 6 below the grate, through which air under pressure
is supplied to the furnace. The working cylinders, of which there are two,
are located at a convenient distance from each other, so that both pistons may
act upon one rocking beam. The cylinders are single acting, that is, the
piston of each is forced upwards by. admitting the compressed heated air and
gases from within the furnace beneath the piston, both pistons being connected
with the rocking beam G by means of the pitmen P, Figure 1, so that the
downward movement of each piston is produced by the upward movement of
the other acting through the pitmen P and the rocking beam G. The
cylinders A, A, are divided into two sections by the annular space B, B,
Figure 1; that part of the cylinder which is above this space is turned true
and polished, so that the piston head D works within it similar to the piston
of a steam engine; the lower portion of the cylinder is left rough. That part
of the piston which is marked D, Figures 1 and 3, is constructed nearly like a
steam engine piston, so far as packing is concerned, and does not need further
explanation than is afforded by the Drawings. Immediately above the part D
and connected to it is the trunk piston C. In this trunk the connecting rod
or pitman P, Figures 1, 2, and 3, plays and is connected to the piston head D
by a joint, as shown in Figure 1, which is kept cool by a free exposure to the
atmosphere and by lubrication, for which good facilities are afforded. The
trunk passes through the upper head i, Figures 1 and 2 of the cylinder, where
it is packed and guided by the gland Z, Figures 1 and 2. The upper cylinder
head is furnished with a valve t, Figure 3, which when forced open by the
compression of the air in the annular space between the trunk and the upper
section of the cylinder permits the said compressed air to pass through the
valve box K, pipes L, L', into the reservoir around the furnace. The upper
cylinder head is furnished with a puppet valve n working in the valve box W,
the purpose of which is to open and to admit air into the annular pump when
the piston descends, and to close and remain closed at other times. This
valve is shown in section in Figure 7, and is made with an air chamber C', in
which a disc n¹ attached to the valve stem 0¹ works. The object of this

page_text: disc n¹ and chamber C is to check the sudden action of the valve n. The air
in the chamber C' acts on the di c n¹ as a cushion, so that it cannot vibrate or
flutter rapidly as it would otherwise. The valve stem 0¹ has a spring s¹
attached to it, so that the valve n is sufficiently checked in its descent to avoid
noise; the outlet valve box K is similar. Extending from and connected to
the piston head D is the cylindrical tank or extension of the piston F, which
is somewhat smaller in diameter than the inside of the cylinder A, and so
long that when the piston is at the lowest point of its downward stroke the
bottom of this tank comes very near to the bottom of the cylinder, there being
always an annular and an end clearance. The groove or chamber B, B,
around the cylinder, communicates with the compressed air in the outlet
(pump) valve chamber, where it is comparatively pure and cool; this com-
munication is made by means of the pipe W₁, Figures 1 and 5, which
terminates in the auxiliary valve box b. The auxiliary valve box b, Figures 1
and 5, contains puppet valves operated by any suitable mechanism, that shown
being a cam on the main shaft, Figures 1, 4, and 5, acting on the levers d², d²,
Figures 1 and 5, and through them upon the valve stems b¹, to open the valve
against the pressure of a spring, the reaction of which assists to close it. It
will be seen that when one of these valves is open air will flow into the
pipe W¹, Figure 1, and thence into the annular space D. If this valve is
open, as it should be after the exhaust valve closes and before the main inlet
opens, all the clearance or unoccupied space in the cylinders and valve
passages will be filled with pure air, but little heated and of density equal to
that within the casing and furnace. The object of thus introducing air
through the pipe W¹, Figures 1 and 5, at this place and time is threefold;
first, by rendering the pressure alike on both sides of the inlet valve it is
balanced and operated in equilibrium, by which the power necessary to work
it is reduced to the minimum; second, by having the space in the cylinder
filled with pure air that which rushes in afterwards from the furnace will not
be likely to carry the solid products of combustion into the joint or annular
space between the finished portions of the cylinders; third, by the introduction
of cool compressed air as described, the temperature of the finished parts of
the piston and cylinder which work in contact with each other are kept
sufficiently cool to admit of efficient lubrication. V, Figure 3, is the inlet
valve and corresponds to the sliding valve on a steam engine; this valve is
open at the commencement of the up stroke of the piston, but closes at about
three-fourths stroke of the same, or at such a point as will give the best result.
As shown in the Drawings this valve V, Figure 3, has besides the disc
common to all puppet valves a hollow cylinder extending upwards, so that the

page_text: valve as a whole forms a cylindrical vessel open at the top. The pipe T,
Figure 3, extends downward in the valve, as shown in the Drawings, so that
when the engine is working a current of cool air is sent down from the air
pump through L, L, and T into said valve at each stroke of the piston, thus
preventing it from being overheated. At about the time the upward move-
ment of the piston ceases and after the inlet valve V has been closed the
exhaust valve V¹ opens and permits the contents of the cylinder to escape and
to be forced out by the descent of the piston into the exhaust pipe N¹,
Figures 8, 5, and 6, and thence into the auxiliary heater B', Figures 4 and 6,
whence it flows into the smoke stack c". The valves shown in the Drawings
are of the puppet variety, and are operated at all times by cams attached to
the shaft N, Figure 3, said shaft being operated by the shaft N", Figure 1,
which connects by gears to the main shaft R. The throttle valve p, Figure 3,
situated in the cold air pipe L, L', serves to regulate the speed of the engine,
being connected by its valve stem to the regulator Q, Figures 1 and 2, so
that as the speed of the engine increases the orifice connecting L, L', is more
or less closed, thus offering a resistance to the motion of the piston, in other
words increasing its back pressure until the speed is reduced to its normal
rate. If the engine is going too slow the reverse of this action takes place.
V", Figure 1, is a small vacuum valve placed near the bottom of each cylinder
and covering an orifice which leads from the open air directly into the
cylinder. The object of this valve is to allow air to flow in and fill the vacuum
that would otherwise be formed while the engine is being started before a
working pressure is produced. B', Figures 5 and 6, represents the auxiliary
heater or steam generator (being in turn both). This heater consists essentially
of a cylinder filled with small metal tubes so arranged that the heated exhaust
air flowing in through the pipe N¹, Figures 5 and 6, shall pass through the
small tubes into the smoke stack c". In the passage of the heated exhaust
air through these tubes it yields a considerable quantity of its caloric, which
is first absorbed by the metal forming the tubes, and then given off to the
cool air surrounding (or in case this is used as a steam generator to the water
surrounding the tubes). When this is used as an auxiliary heater the cool air
passes in through the pipe f, Figures 5 and 6, and having circulated around
and among the tubes it goes back through the pipe Y into g, and thence
through a, Figure 6, into the air space around the furnace between J and J',
Figure 2; or some of it may pass through the pipe a', Figure 6, into the
ash-pit and then into the furnace. The pipes ƒ and g, Figures 5 and 6, are
each provided with valves, as shown in Figure 5, so that either one of them
may be closed. Iff be closed the air would not circulate through the auxiliary

page_text: heater. When it is desirable to use B¹, Figures 5 and 6, as a steam
generator the pipes f and Y are disconnected and their corresponding orifices
closed and made air-tight. The steam pipe 911, Figure 5, is then attached,
leading from the auxiliary beater to the auxiliary valve boxes b, as shown in
Figure 5; the generator B₁ is partially filled with water, and is ready for
operation for generating steam, which steam may be used to increase the
power of the engine, or for heating or other mechanical purposes. In
starting a fire on the grate the main inlet and exhaust valves should be opened
as well as the ash-pit door to establish a draft through the engine by way of
the cylinder and auxiliary heater. If sufficient draft cannot be obtained in
this way then the valve or damper in the direct draft pipe c' should be opened
and a direct upward draft be thereby established. When the fuel is well
ignited all the doors and valves through which air can pass to or from the
furnace should be closed and made air-tight. The main shaft of the engine
itself may be rotated by suitable means, when the pumps forming part of the
engine will supply the air needed in the furnace. When sufficient pressure
has been generated to rotate the engine the extraneous force may be
discontinued, as the expansion of the air supplied by the pumps of the engine
will continue to increase the pressure within the furnace until the engine has
some work applied to it to absorb the power generated.
In witness whereof, I, the said Philander Shaw, have hereunto set my
hand and seal, this Fourth day of September, in the year of our Lord
One thousand eight hundred and sixty-seven.
Witness,
GEORGE HASELTINE,
Civil Engineer,
8, Southampton Buildings,
London.
PHILANDER SHAW. (L.s.)