IMPROVE- MENTS IN HOT AIR MOTOR ENGINES
Year: 1876

page_text: LETTERS PATENT to Charles Denton Abel, of No. 20, Southampton Buildings,
Chancery Lanc, in the County of Middlesex, for the Invention of "IMPROVE-
MENTS IN HOT AIR MOTOR ENGINES." A communication from abroad by Julius
Hock & Co., of Vienna, in the Austrian Empire
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 9th September 1870.
CHARLES DENTON ABEL, of No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "IMPROVEMENTS IN HOT AIR MOTOR ENGINES."
"
This Invention relates to motor engines in which cold air forced into a tight fire-
box is heated, and along with the products of combustion is made to act on a piston
for the production of motive power.
According to the improved construction the base of the engine contains a fire-
box lined with refractory material, having a fire-grate and an ash-pit and fire-door,
both of which can be closed air-tight. There is also in the base a chamber
communicating with the space above the fire-grate, and a passage leading to below
the fire-grate, both the chamber and the passage being made to communicate by
means of regulating valves actuated by a rotary governor with the air supply pipe,
and the said air chamber also has a loaded escape valve which can be acted upon
by the governor. Over the fire-grate is a fuel hopper provided with a tight door
at the side, and a valve in the-bottom-for the supply of fuel while the engine is at
work.
Above the fire-box is placed a vertical cylinder, which is fitted with the working
piston provided with a shield projecting down from it to prevent the hot air from
affecting the smooth working faces of the cylinder and piston. The cylinder is
open to the atmosphere at top, and carries by means of open brackets an upper
cylinder which is of smaller diameter than the lower one, and which is also fitted
with a piston rigidly connected to the lower piston by an open frame, so as to
move with it for the purpose of drawing cold air through a supply valve on the
upper piston, and forcing the air through a delivery valve on the top cover of the
upper cylinder. Between the two pistons is mounted a crank shaft, the crank

page_text: :
of which is connected by a connecting rod to the lower piston, and on this shaft
is a fly wheel, or a pair of fly wheels, one on each side of the cylinder. This shaft
drives by gearing a rotary governor of ordinary construction, and also a counter-
shaft, which by means of a crank or eccentric works a rocking shaft having on it
cam-shaped arms that work supply and discharge valves placed in a box com-
municating with the working cylinder, the fire-box, and the atmosphere. The
supply and discharge valves are arranged to open downwards in the valve box,
which is divided into two compartments, one for each valve.
The compartment containing the supply valve communicates below the latter
with the space above the fire-grate, and above the same with a passage leading
into the working cylinder; the other compartment communicates below its valve
with the same passage leading to the cylinder, and above the valve with the
atmosphere-through a side opening. Beneath the two valves the valve box has a
cover, which is pressed air-tight against its seat by screws screwed through a
bridgė piece, so that by unscrewing these screws the cover may be readily removed
for gaining access to the valves and passages The valves are held up against their
seats by a strong spring regulated by a screw and connected to the middle of a sway
beam jointed to both valve spindles.
The working piston being down, the supply valve opened, and the discharge
valve closed, hot air from the fire-box enters the working cylinder and propels the
piston upwards The upper piston being thus moved upwards forces fresh cold air
down a pipe into the regulating valve box below, whence a greater or less portion
of it passes through the fire supporting combustion, and becoming heated and
mingled with the products of combustion, and then passes, together with another.
portion of the air which enters above the grate, into the working cylinder. When
the piston has reached the upper extreme of its stroke the supply valvė is closed
and the discharge valve is opened, whereupon the piston descends, the upper piston
descending with it and drawing in a fresh charge of air.
The governor being connected to the valves in the regulating valve box regulates
the speed of the engine in the following manner :-Should the engine work too
quickly the governor moves these valves so as to cause a smaller quantity of the air
from the supply pipe to pass through the fire and a greater quantity through the
before-mentioned chamber, whence, after becoining somewhat heated, it passes to
the space above the fire, and thence to the engine. This has the effect of rendering
the combustion less active, and of imparting less heat to the working fluid which
enters the cylinder. Should a sudden increase of speed require a still more rapid
reduction of motive power the governor will open the loaded escape valve of the
air chamber, and thus allow a certain quantity of the air to escape. On the other
hand, if the engine is working too slowly the valves are so moved by the governor
that a greater proportion of the air charge is passed through the fire, and less above
it, thus rendering the combustion inore active.
Where the fire and ash-pit doors are situated the casing of the fire-box is made
double, and the air from the air chamber is made to pass into this space and to
enter the fire-place through side openings in the door frame, whereby the fire-doors
are kept cool.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Denton Abel in the Great Seal Patent Office on the 6th
March 1877.
CHARLES DENTON ABEL, of No. 20, Southampton Buildings, Chancery Lane, in
the County of Middlesex "IMPROVEMENTS IN HOT AIR MOTOR ENGINES." A
communication from abroad by Julius Hock & Co., of Vienna, in the Austrian
Empire
This Invention relates to motor encines in which cold air forced into a tight fire.

page_text: box is heated and along with the products of combustion is made to act on a piston
for the production of motive power.
According to the improved construction the base of the engine contains a fire-box
lined with refractory material, having a fire-grate and an ash-pit and fire-door both
of which can be closed air-tight. There is also in the base a chamber communicating
with the space above the fire-grate, and a passage leading to below the fire-grate,
both the chamber and the passage being made to communicate by means of regu-
lating valves actuated by a rotary governor with the air supply pipe, and the said
air chamber also has a loaded escape valve which can be acted upon by the
governor. Over the fire-grate is a fuel hopper provided with a tight door at the
side and a valve in the bottom for the supply of fuel while the engine is at
work.
Above the fire-box is placed a vertical cylinder, which is fitted with the working
piston provided with a shield projecting down from it to prevent the hot air from
affecting the smooth working faces of the cylinder and piston. The cylinder is
open to the atmosphere at top, and carries by means of open brackets an upper
cylinder which is of smaller diameter than the lower one, and which is also fitted
with a piston rigidly connected to the lower piston by an open frame, so as to move
with it for the purpose of drawing cold air through a supply valve on the upper
piston, and forcing the air through a delivery valve on the top cover of the upper
cylinder Between the two pistons is mounted a crank shaft, the crank of which is
connected by a connecting rod to the lower piston, and on the shaft is a fly wheel,
or a pair of fly wheels, one on each side of the cylinder. This shaft drives by
gearing a rotary governor of ordinary construction, and also a countershaft, which
by means of a crank or eccentric works a rocking shaft having on it cam-shaped
arms that work supply and discharge valves placed in a box communicating with
the working cylinder, the fire-box, and the atmosphere. The supply and discharge
valves are arranged to open downwards in the valve box, which is divided into two
compartments, one for each valve.
The compartment containing the supply valve communicates below the latter
with the space above the fire-grate, and above the same with a passage leading into
the working cylinder; the other compartment communicates below its valve with
the same passage leading to the cylinder, and above the valve with the atmosphere
through a side opening. Beneath the two valves the valve box has a cover which
is pressed air-tight against its sent by screws screwed through a bridge piece, so
that by unscrewing these screws the cover may be readily removed for gaining
access to the valves and passages The valves are held up against their seats by a
strong spring regulated by a screw and connected to the middle of a sway beam
jointed to both valve spindles.
The working piston being down, the supply valve opened, and the discharge
valve closed, hot air from the fire-box enters the working cylinder and propels the
piston upwards. The upper piston being thus moved upwards forces fresh cold air
down a pipe into the regulating valve box below, whence a greater or less portion
of it passes through the fire supporting combustion and becoming heated and
mingled with the products of combustion, and then passes, together with another
portion of the air which enters above the grate into the working cylinder. When
the piston has reached the upper extreme of its stroke, the supply valve is closed
and the discharge valve is opened, whereupon the piston descends, the upper piston
descending with it and drawing in a fresh charge of air
The governor being connected to the valves in the regulating valve box, regulates
the speed of the engine in the following manner -Should the engine work too
quickly the governor moves these valves so as to cause a smaller quantity of the
air from the supply pipe to pass through the fire and a greater quantity through
the before-mentioned chamber, whence after becoming somewhat heated it passes to
the space above the fire and thence to the engine. This has the effect of rendering
the combustion less active and of imparting less heat to the working fluid which
enters the cylinder. Should a sudden increase of speed require a still more rapid

page_text: reduction of motive, power, the governor will open the loaded escape valve of the
air chamber and thus allow a certain quantity of the air to escape. On the other
hand, if the engine, is working too slowly the valves are so moved by the governor
that a greater proportion of the air charge is passed through the fire and less above
.it, thus rendering the combustion more active.
Where the fire and ash-pit doors are situated the casing of the firo-box is made
double, and the air from the air chamber is made to pass into this space and to
enter the fire-place, through side openings.in.the door frame, whereby the fire-doors
arc.kept cool.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 represents a vertical section; Fig. 2, an end view partly in section,, and
Fig. 3, a plan partly in section of a hot air motor, engine according to this
"Invention.
"
a is the fire-box lined with fire-brick and fitted with air-tight fire and ash
doors b, b. Over the fire-grate is placed a fuel hopper c with a tight door and
valve, so that.fuel can be supplied to the fire without permitting escapo of the gases
from the fire-box; d is a passage leading from the fire-box to the valve box f,,in
which are fitted the valve g for admission to the cylinder and the valve h for
emission from the cylinder to the chimney. The engine being single acting, the
working cylinder jis open at the top and terminates in four flanges i, i, two, of
which carry the shaft bearings h, k, and the other two support the air pump,m.
The working piston n and, the pump piston o are rigidly connected together by an
open framing through which passes the crank shaft p. The crank thereon is
connected to the working piston by the connecting rod g. The piston is provided
at its upper end with leather packing, and is protected by a fender casing n'. The
pump piston o is provided with a suction valve s, and the cover of the pump
contains the discharge valve t opening into a chamber whence the cold air pipe,v
leads down to the regulating valve box u which is intermediate to the preliminary
, heating chamber w and the ash-pit. The inain shaft p by means of equal goaring
drives a countershaft y from which by bevil gearing is driven the governor The
governor lever &¹ is connected by a rod 22 to the valves.in the box.u, so that when
the engine is at rest or moving slowly the cold air arriving from the pump m by
the passage v is all delivered into the ash-pit through the passage v¹ and supplies
and passes through the fire, but when the engine works too rapidly the valves in u
are lowered by the action of the governor, permitting more or less of the cold air to
pass into the chamber w, whence it is delivered into the casing b¹ from which it
escapes by orifices b² behind the fire-door b.into the chamber a above the fire, ul¹ is
the escape valve which is kept closed by a loaded lever us, but when by the action
of the governor the stem of the valves above it has so far descended as to close the
upper valve and open the lower valve, thereby causing all the air to pass into the
chamber above the fire, a still farther descent of the said stem causes the escape
valve u¹ to open and thereby relieve the pressure of the supplied air. In order to
permit of this farther descent of the stem it is made to act on the valves abovo
through a spring u³, as shewn in Fig. 2; thus the governor not only effects the
regulation of the engine speed by causing more or less of the air to pass above the
fire, but also, in case of suddenly increased speed of the engine, it opens the escape
valve, thereby at once reducing the pressure of the acting fluid as well as the
intensity of the combustion. The countershaft y by means of a crank and
connecting rod y works a rocking shaft f¹, cams on which move the valves g
and h downwards so as to admit heated air to the cylinder j for the upstroke of its
piston, and to allow the escape of the contents of that cylinder for the downstroke.
The valve rods of g and h are jointed to opposite ends of a sway beam g², the
middle of which is connected to a spring h³ which closes either valve when it is not
depressed by the cam on the rocking shaft f¹. Access is given to the valves g and h
by the removeable cover f, which can be readily removed by slacking the screws
of its yoke, and replaced and closed air-tight by tightening them.

page_text: Having thus described the nature of the said Invention, and in what manner
the same is to be performed, as communicated to me by my foreign correspondents,
I claim,―
First. The construction of a hot air motor engine having for its base the fire-box
on which is placed the working cylinder surmounted by an inverted air pump,
arranged and operating substantially as herein described.
Second. In engines of the kind referred to in the preceding claim, the arrange-
ment of the valve box u and its valves in combination with a governor z, and with
the air supply passage v, the passages and chambers v¹, w, and 6', and orifices 6º,
whereby the regulation of the engine is effected, substantially as herein described.
Third. The use for hot air motor engines of the valve box f with its valves g
and h opened by cams acting in opposition to a single spring connected to both
valves through a sway beam, substantially as and for the purposes herein set
forth.
In witness whereof, I, the said Charles Denton Abel, have hereunto set my
hand and seal, this Nineteenth day of February, in the year of our Lord One
thousand eight hundred and seventy-seven.