IMPROVEMENTS IN HOT-AIR ENGINES
Year: 1863

page_text: LETTERS PATENT to George Tomlinson Bousfield, of Loughborough Park,
Brixton, in the County of Surrey, for the Invention of " IMPROVEMENTS IN
HOT-AIR ENGINES."-A communication from abroad by Elmer Townsend,
residing at Boston, Massachusetts, United States of America.
Sealed the 6th April 1863, and dated the 17th January 1863.
COMPLETE SPECIFICATION filed by the said George Tomlinson Bousfield
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 17th January 1863, pursuant to the 9th Section
of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
TOMLINSON BOUSFIELD, of Loughborough Park, Brixton, in the County of
Surrey, do hereby declare that I am in possession of an Invention for "IMPROVE-
MENTS IN HOT-AIR ENGINES," that the same has been communicated to me from
abroad by Elmer Townsend, a person resident at Boston, Massachusetts,
United States of America, and I, the said George Tomlinson Bousfield, do hereby
declare the nature of the said Invention, and in what manner the same is to
performed, is particularly described and ascertained in and by the following
statement thereof, that is to say :-
Figure 1 is a perspective view; Figure 2, a plan; Figure 3, a vertical
section upon the line x, x, of Figure 2; Figure 4, an underneath view of the
hollow piston V, the bottom plate being removed to show the deflecting plato
within. The body or exterior casing A rests upon the base B; the fire-box D

page_text: is made of a single casting G, thus avoiding all joints at which leakages might
occur, and to protect the iron from the intense heat of the fire the box is
surrounded upon the inside with fire-brick or soapstone E. The upper plate
of the casting G is also protected by a slab or plate of soapstone or fire-brick
F which effectually screens it from the direct action of the fire. The cylinder
is divided into a lower portion H, and an upper portion R. The lower
portion is formed of a single casting H2, and is inserted at the top of the
casing A, the flange * of the casting resting upon the top of the casing A.
The space g between the casting and the casing is then filled with calcined
plaster or some equivalent non-conducting substance. This may be done by
inserting the casting and placing the casing over it. The lower casting G is
placed with its upper plate supporting the lower plate H of the cylinder, and
the space, between the lower casting and the casing is also filled with
plaster. The entire furnace, as well as that portion of the cylinder which is
exposed to the. heat, is thus surrounded by a non-conducting substance, by
which great economy of heat is effected.
The fuel is fed to the furnace in the following manner :-I is a cylinder
having a tight fitting cover K, which is secured by clamps or screws in any
well known manner to its seat.
The cover shown in Figure 1 is curved, but in practice it is preferable to
make them flat, as they a are more easily fitted and made tight than when
curved. Within this cylinder is a piston L, having a rod a, which passes
through a stuffing box in the end of the cylinder, and is furnished with a
handle by which the piston may be manipulated. From the top of the
cylinder rises a narrow chamber M, in which slides a disc or plate valve N,
a portion of which is seen in Figure 1; the cylinder and chamber being
broken away to show it; the valve N is manipulated by means of a rod b³,
rising from the plate which passes through a stuffing box c in the top of the
chamber M. When the valve is down as represented in Figure 1, it cuts off
the communication between the furnace and the cylinder. When the fire
is to be replinished the cover K is removed and the piston L is drawn back,
the coal is then put into the cylinder, the cover is replaced, the valve N is
raised, and the coal is forced into the furnace by means of the rod a. O, is a
tight-fitting door through which the furnace may be fed by hand, and Pa similar
door to the ash-pit. The heated air from the furnace is admitted to the cylinder
through a valve chest S and valve f, and is exhausted through the valve g
and pipe h into a chimney or other suitable conduit, there being a passage d
fitted air-tight to the furnace and the valve chest and a corresponding opening
in the fire-brick lining. The passage from the valve chest to the cylinder is

page_text: also fitted air tight at each end. The valve rods i and k which pass through
the stuffing boxes, ³, are actuated in a well known manner by tappets upon
a rock shaft l, which is set in motion by an eccentric or by a crank upon the
shaft G, one end of the rod T being connected with the crank, and the other
with the arm n upon the rock shaft.
The most serious difficulty thus far encountered in the construction and
operation of hot-air engines arises from the great heat to which the cylinder
and piston are exposed, and the consequent destruction of the oil used for
lubricating them. To remedy this inconvenience I adopt the following
construction:-The upper portion R of the cylinder, or that portion which
comes in contact with the piston, is isolated from the lower portion which
receives the heated air, a cylinder U of thin sheet metal being interposed.
between them. This cylinder is secured between the flanges h³ and q, and
the whole are held together by the bolts p. The cylinder U being made as
thin as may be and to stand the pressure within, and being constantly
refrigerated by radiation and by exposure to the atmosphere, transmits only a
trifling amount of heat to the cylinder R, which thus remains constantly so
cool as not to destroy the oil used to lubricate it. The piston V is hollow
and has an open cylinder t projecting above its upper plate 1, a ring of
packings being secured to the upper edge of the cylinder by a metallic
ring n² and screws o³. Beneath the piston V is the prolongation W, which
fits loosely in the cylinder and descends on the down stroke to near the
bottom of the chamber H. For the purpose of more completely cooling the
piston, the air for driving the engine is all passed through it on its way to the
fire-box by the following means:-Above the cylinder and secured to the top
thereof by screw bolts, or otherwise, is the air pump A, in which works
the piston x, the rod z of which is hollow and is attached to the u-per
plate r of the piston V. The piston x is hollow and has two flat valves 1
and 2 opening inwards; the upper head of the air pump has a valve 3 opening
downwards, and the lower head or valve 4 opening upwards by means of the
hollow rod; the cavity in the piston V is connected with the cavity in the
piston ; a pipe y extending up from the cavity in the piston V, slides
air-tight within a stationary pipe Z rising from the base a³ of the air pump.
The pipe Z is bent down and enters a passage x, passing down within the
casing A; from this passage there are two pipes d and fa, leading the one to
the fire-box and the other to the ash-pit beneath the grate bars C.
The operation of this part of the engine is as follows:-As the piston V rises
(carrying with it the air pump piston a) the valves 4 and 1 are opened, and
the valves 2 and 3 are closed, the air above the piston a passing through the

page_text: hollow rod to the interior of the piston V up through the pipe y down through
the pipe Z and passage to the fire-box. At the same time that this is
taking place the valve 4 in the bottom of the air pump is opened and air
enters beneath the piston x. On the descent of the pistons V and x the
valves 2 and 3 are opened, and 1 and 4 are closed, and the air is forced
through the chamber in the piston V as before to the fire-box, and thus a
constant current of air is passed through the piston by which any heat that
may be conducted to it through the prolongation W, is carried off and it is
kept so cool that the oil used for lubricating the piston is not destroyed or
changed. The air is made to circulate more perfectly through the piston by
the deflecting plate C2 (Figures 3 and 4). In order to regulate the force
with which the fire is urged to accord with the work upon the engine, the
pipes d and f, one of which enters the fire-box above the fire, and the other
the ash-pit beneath the grate bars, are furnished with valves 5 and 6, the
rods 7 and 8 of which pass out through stuffing boxes 9 and 10 and aro
manipulated by hand. When the upper valve is opened and the lower one
closed the air is all thrown in above the fire, and in proportion as the lower
valve is opened more air is admitted beneath the grate bars and is passed
through the fire, by which the fire is urged to a greater intensity. The
working piston is connected by means of rods o³, with the up and down
beam D, that vibrates upon a standard E, rising from the main cylinder
and from which the power is communicated by the connecting rod F to the
driving shaft G³, which carries the fly wheel H³.
For the purpose of regulating the speed of the engine the following device
is employed: One of the legs. (Figure 2) which supports the air pump has
a passage through it which communicates with the interior of the air pump,
and with a pipe k³, near to the outer end of which are one or more openings
through which air from the pump is allowed to escape when the openings are
not covered by the enclosing sleeve m²; this sleeve is operated by the governor
balls, which slide upon the arms c³ projecting from another sleeve 2³ which is
prevented from moving longitudinally on the pipe by collars 11 and 12.
This sleeve, together with the sleeve m³, is revolved upon the pipe ³, by a band
or strap from the pulley m on the main shaft running upon the pulley b³, and
thus when the rate of motion of the engine exceeds the desired limit the holes
in the pipe will be uncovered and air will be permitted to escape, thus
modifying the pressure within the fire-box and cylinder.
What I claim as the Invention and desire to secure by Letters Patent is
making the fire-box of a single casting and lining the same with fire-brick
upon all sides except the bottom, as set forth.

page_text: I also claim the castings G and H' in combination with the exterior
casing A, the space between them being filled with plaster or its equivalent
for the purpose specified.
I also claim passing the air for operating the engine through the piston,
substantially as described, for the purpose set forth.
I also claim dividing the working cylinder into two portions and uniting
the two by means of a thin metallic cylinder, substantially as described, for the
purpose set forth.
I also claim the device for feeding the furnace, consisting of the cylinder I,
piston L, and valve N, arranged and operating as set forth for the purpose of
feeding the furnace without stopping the engine.
I also claim the induction pipes d, f, arranged and operating as described,
in combination with the pipe or passage which brings the air from the air
pump to the furnace for the purpose of regulating the intensity of the fire, as
set forth.
I also claim the hollow piston V in combination with the hollow piston x
and hollow rod z, and with the pipe Y attached to the main piston, and tho
stationary pipe Z operating as described.
I also claim, in combination with an air engine in which the cylinder is
separated from the fire-box by tight partitions, as set forth, the arrangement
of the valves and their communicating chambers and passages within a valve
chest upon the outside shell or casing, as set forth.
I also claim regulating the speed of the engine by exhausting the air at
some point after it has passed the force pump by means of a governor, as set
forth.
I also claim placing the force pump upon the top of the cylinder and
attaching its piston rod directly to the piston of the working cylinder, as set
forth.
In witness whereof, I, the said George Tomlinson Bousfield, have here-
unto set my hand and seal, this Seventeenth day of January, in
the year of our Lord One thousand eight hundred and sixty-