A New or Improved Hot Air Engine or Aerothermic Motor.
Year: 1888

page_text: Date of Application, 14th Jan., 1888'
Complete Specification Left, 4th Oct., 1888
Complete Specification Accepted, 9th Nov, 1888
PROVISIONAL SPECIFICATION.
A New or Improved Hot Air Engine or Aerothermic Motor.
1, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, do hereby declare the nature of the said invention of "A NEW OR
which has been communicated to
me from abroad by Lucien Genty of 48 rue de Bondy, Paris, in the Republic of
France, Engineer of Mines, to be as follows:-
IMPROVED HOT AIR ENGINE OR AEROTHERMIC MOTOR
This invention relates to a new or improved hot air engine or aerothermic motor
arranged and operating as hereinafter described.
The working of this motor is as follows:-
Air from the atmosphere is compressed in a reservoir or chamber communicating
with an exchanger or heater which delivers it in the furnace at a temperature as near
as desired to that of the escaping or exhaust gases.
This air whose temperature is raised by the heat of the escaping gases is distributed
in a furnace or combustion chamber whence it issues at an elevated temperature
varying according to the action of the engine. It then enters the cylinder where it
acts first under constant pressure and afterwards by expansion which is produced by
the excess heat which it took up in the combustion chamber being subsequently
discharged or exhausted at atmospheric pressure into the exchanger or heater herein
before referred to, whence it ultimately escapes into the atmosphere.
Description of the parts. This hot air engine or acrothermic motor is constructed
with a feed pump connected to a compression chamber by means of a flange and
bolts. The valves are flat and packed with leather being of such a shape or form
that the waste or inactive space beneath the piston is limited to that reserved at
the end of the stroke between the piston and the end of the cylinder.
The connecting rod attached to the piston is made with two joints having their axes
arranged at right angles so that the piston never binds or sticks in the cylinder how-
ever irregularly the beam may be centred. The cast iron compression chamber forms
part of a support or bed plate one end of which carries the two plummer blocks of the
crank or driving shaft the other end presenting a broad plate connected to the
compression chamber by webs and to which the driving cylinder is bolted.

page_text: The compression chamber communicates with a heater through a tube and starting
valve. This heater or exchanger of temperature is constructed similarly to the body
of a tubular boiler.
In this heater the air is heated to a temperature more nearly approaching that
of the exhaust according to the area of surface presented by the tubes. This heated
air enters a tube passing through the side of the bed plate and leading to an admission
valve.
The admission valve box contains a valve formed by a number of superposed sheets
of asbestos paper or fabric or by a disc formed by a truncated cone of compressed
asbestos tightly fixed between two discs of metal. This valve closes the passage per-
fectly at an elevated temperature and can be easily repaired by renewing the asbestos
when required.
The compressed and heated air admitted by the valve enters a distribution box
where it is divided into two streams of different volumes according to the position of
the distribution valve. One portion of the air passes along a passage leading to an
annular passage formed around the fire bricks at the lower part of a combustion
chamber whence the air is delivered through a series of horizontal tuyeres in the
thickness of the bricks to fuel placed in the combustion chamber and consisting of
coke for example. This coke is maintained at a bright red or even white heat by
means of the fire proof and heat retaining casing in which it is contained. Combustion
producing carbonic acid takes place at first after which a partial decomposition occurs
and a flame composed of nitrogen carbonic acid and carbonic oxide escapes from the
upper surface of the fuel. This flame meets a thin stream of hot air delivered by an
annular tuyere or opening formed between the upper bricks of the combustion
chamber and the lower bricks of an expansion chamber and communicating with
a passage which receives the second portion of the air delivered from the distribution
valve.
The mixture resulting from the meeting of the two gaseous streams effects the com-
plete combustion of the carbonic oxide contained in the flame. This combustion is
promoted or assisted by a throat or contraction which reverberates and concentrates
the heat near the upper tuyere and at the same time parily prevents radiation of heat
from the red hot coke against the sides of the expansion chamber.
The mixing continues in a cylindrical passage connecting the combustion chamber
with the expansion chamber which is supplied with a gaseous mass under pressure
and at an elevated temperature regulated by the position of the distribution valve.
This distribution valve is connected with a small piston loaded by a weight and by
a spring and working in a cylinder connected by a small tube with the chamber or
reservoir. Each degree of pressure between certain fixed limits corresponds with a
different position in which the piston is in equilibrium. When the pressure falls in
the reservoir, the piston yielding to the action of the counterweight and spring tends
to descend and aller the position of the distributer in such a manner as to increase
the proportion of air which passes through the fuel and thus raises the working
temperature.
The reverse takes place when the pressure approaches the maximum limit assigned
to it. After the valve has closed the air introduced into the expansion chamber and
that contained in the combustion chamber increase in volume continuing to force up
the motor piston and thus perform work by expansion at the expense of their internal
heat and of the heat generated in the fuel. At the end of the upward stroke of the
piston an exhaust valve, similarly arranged to the admission valve, opens and the air
in the expansion chamber falls to atmospheric pressure and is expelled being driven
into the heater by the descent of the piston. The air thus expelled proceeds from the
box of the exhaust valve, to a head or chamber in the heater through a bent tube at a
temperature more or less elevated according to the working of the engine.
At the further extremity of the heater the exhaust gases which have been cooled to
about 210 degrees Centigrade, are collected in a chamber, whence they are discharged
into the atmosphere through a pipe or chiuney.
The metal casing of the combustion chamber can be detached from the expansion

page_text: chamber by unscrewing bolts. The combustion chamber then rests upon small wheels
or rollers upon which it may be moved.
At its lower part this chamber is provided with an opening closed by a tight fitting
door to facilitate lighting and cleaning. This door is provided on its inner side withi
a fire brick which fits into and fills the hole in the lining of the combustion chamber.
An apparatus for the introduction of fuel during the working is provided in the side
of the expansion chamber furthest from the support.
This apparatus consists of a chamber communicating with the atmosphere through
an outer door and with the expansion chamber through an inner door. These doors
are of metal and packed with asbestos paper.
The outer door is in the form of a flap hinged on an axis being pressed against
the orifice of the chamber when closed, by means of pivoted screws or other suitable
device.
The inner door or flap is operated by two flat bars connected to levers and working
against the sides of the feed chamber. These bars and levers may work in contact
with the fuel or they may be protected or enclosed by a casing or covering of sheet
metal suitably arranged.
The levers are fixed on a shaft passing to the exterior through an asbestos packing
and having a weighted lever fixed on its outer end. This weighted lever serves to
maintain the door normally closed.
In order to introduce a charge of fresh fuel into the combustion chamber by means
of this apparatus, the outer door is first opened and the fuel is thrown into the
chamber after which the door is closed. It then suffices to raise the weighted lever
in order to open the inner door or flap and allow the fuel to fall down the inclined
passage which conducts it to the combustion chamber.
The expansion chamber is arranged above the combustion chamber and is connected
at its upper part with the base of a working cylinder. The said expansion chamber
is formed by a metallic casing lined with fire bricks to protect the metal from the
action of the flame and diminish the loss of heat.
The working or motor cylinder is provided externally with ribs or projections
which serve to conduct or throw off into the atmosphere the. heat which it receives
from the expansion chamber. This cylinder is attached to the body or base of the
engine by the broad plate herein before referred to.
In this cylinder works a hollow motor piston provided at its upper part forming
a trunk working in the turned portion of the cylinder with a packing of asbestos and
plumbago. A packing of this description may be formed by means of a rope of
asbestos covered with plumbagino and coiled in a helix around the upper part of
the piston which is somewhat reduced in diameter for this purpose. A ring which can
be adjusted by means of nuts enables this packing to be compressed and expanded so
as to compensate for wear.
The connecting rod through which the motor piston acts on the beam is attached
to the piston by a flexible blade or spring of metal. One extremity of this blade
is secured to the lower end of the connecting rod and the other extremity is
attached to a cross bar bolted to two projections cast on the inside of the piston
trunk and passing through an eye or opening formed in the connecting rod.
This mode of connection presents the following advantages. It obviates the friction
wear and necessity for lubrication in a place inconvenient of access and exposed to
an elevated temperature. The connecting rod terminates at its upper extremity in a
bearing which is attached to it in such a manner that the connection between
the connecting rod and the beam presents two axes at right angles to one another.
This arrangement is adopted in all the joints of the other connecting rods in the
motor the object being to allow for the distortion arising from unequal expansion and
contraction of the supports and moving parts and obviate the straining of the connec-
tions and disturbance of the fitting that would otherwise be liable to be produced by
this cause.
The crank shaft carries the following parts viz. a fly wheel, an exhaust cam, an
admission cam and a toothed wheel driving a centrifugal governor.

page_text: The exhaust cam operates the corresponding valve through the intervention
of a bellerank lever and a connecting rod, working a second bell crank lever.
The admission cam is so arranged as to enable the admission or supply of air to the
combustion chamber to be regulated or controlled in such a manner as to maintain a
uniform speed notwithstanding variations in the load or work performed. The lifting
part of the cam is formed along a generating line of the cylinder forming the cam so
that the valve is invariably opened when the crank shaft is in a certain position.
The drop of the cam on the other hand is in the form of a portion of a helix so that the
length of the period of admission varies according to the relative position of the cam
and a small roller at the end of a lever operating the valve by the intervention of
a rod and lever.
The speed of the engine is maintained between certain predetermined limits by
the action of a centrifugal governor which automatically increases or diminishes the
period of admission according to the requirements of the motor by shifting the admis-
sion lever along the cam.
The axis of this lever is formed by a screw which works in the lever as in a nut.
This screw is provided at one extremity with a friction disc placed between two plates
connected together. These two plates rotate with the governor spindle and are
capable of sliding longitudinally thereon when acted on by a rod connected to the
governor balls or weights. So long as the speed keeps within the prescribed limits
these plates are held out of contact with the disc but when on the contrary the speed
attains the higher or lower limit the disc on the screw is caused to engage with
one or the other of the plates and the screw rotates on its axis so as to displace
the admission lever in the direction required to restore the normal action of the
engine.
When from any cause whatever the engine running at a speed below the fixed
limit would be liable to cause the lever to be screwed hard up at the end of the
screwed axis this inconvenience is prevented by a small stop lever which being acted
on by the admission lever raises the plates and throws them out of gear with the
disc.

page_text: COMPLETE SPECIFICATION.
A New or Improved Hot Air Engine or Aerothermic Motor.
i, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman, do hereby declare the nature of this Invention which has been com-
municated to me from abroad by Lucien Genty of 48 rue de Bondy, Paris in the
Republic of France, Engineer and in what manner the same is to be performed to
be particularly described and ascertained in and by the following statement:
This Invention relates to a new or improved hot air engine or aerothermic motor
arranged and operating as herein before described with reference to the accompanying
drawings.
Figure 1 is a general view showing a side elevation of an aerothermic motor con-
structed according to this Invention.
Figure 2 shows the motor in plan the beam and connecting rod being removed.
Figure 3 is a plan of the beam.
Figure 4 represents a longitudinal section of the motor.
Figure represents a vertical section taken through the cylinder and valves.
Figure 6 represents a vertical section of the centrifugal governor.
Figures 7 and 8 represent the small stop lever of the governor in elevation and in
plan respectively.
The working of this motor is as follows
Air from the atmosphere is compressed in a reservoir or chamber communicating
with an exchanger or heater which delivers it in the furnace at a temperature as near
as desired to that of the escaping or exhaust gases. This air whose temperature is
raised by the heat of the escaping or exhaust gases is distributed in a furnace or
combustion chamber whence it issues at an elevated temperature varying according to
the action of the engine. It then enters the cylinder where it acts first under constant
pressure and afterwards by expansion which is produced by the excess heat which it
took up in the combustion chamber being subsequently discharged or exhausted at
atmospheric pressure into the exchanger or heater hereinbefore referred to whence
it ultimately escapes into the atmosphere.
Description of the parts. This hot air engine or aerothermic motor as illustrated
in the drawing is constructed with a feed pump A connected to a compression
chamber R Figure 4 by means of a flange and bolts. The valves are flat and packed
with leather being of such a shape or form that the waste or inactive space beneath
the piston is limited to that reserved at the end of the stroke between the piston and
the end of the cylinder.
The connecting rod attached to the piston is made with two joints having their axes
arranged at right angles so that the piston never binds or sticks in the cylinder how-
ever irregularly the beam B may be centred. The cast iron compression chamber R
forms part of a support or bed plate one end of which carries the two plummer blocks
of the crank or driving shaft the other end presenting a broad plate connected to the
compression chamber by webs and to which the driving cylinder C is bolted.
The compression chamber R communicates with a heater E through a tube T and
starting valve V. This heater or exchanger of temperature is constructed similarly to
the body of a tubular boiler.

page_text: In this heater the air is heated to a temperature more nearly approaching that of the
exhaust according to the area of surface presented by the tubes. This heated air
enters a tube T2 Figure 1. passing through the side of the bed plate and leading to an
admission valve H Figures 1 and 5.
The admission valve box is shown in section at II Figure 5 and contains a valve S
formed by a number of superposed sheets of asbestos paper or fabric or by a disc or
truncated cone of compressed asbestos tightly fixed between two discs of metal. This
valve closes the passage perfectly at an elevated temperature and can be easily repaired
by renewing the asbestos when required.
The compressed and heated air admitted by the valve S enters a distribution box Y
where it is divided into two streams of different volumes according to the position of
the distribution valve. One portion of the air passes along a passage (leading to
an annular passage U formed around the firebricks at the lower part of a combustion
chamber whence the air is delivered through a series of horizontal tuyeres in tho
thickness of the bricks to fuel placed in the combustion chamber and consisting of
coke for example. This coke is maintained at a bright red or even white heat
by means of the fire proof and heat retaining casing in which it is contained.
Combustion producing carbonic acid takes place at first after which a partial
decomposition occurs and a flame composed of nitrogen carbonic acid and carbonic
oxide escapes from the upper surface of the fuel. This flame meets a thin stream
of bot air delivered by an annular tuyere or opening X X formed between the
upper bricks of the combustion chamber and the lower bricks of an expansion
chamber G and communicating with a passage which receives the second
portion of the air delivered from the distribution valve.
The mixture resulting from the meeting of the two gaseous streams effects the
complete combustion of the carbonic oxide contained in the flame. This combus-
tion is promoted or assisted by a throat or contraction which reverberates and
concentrates the heat near the tuyere X and at the same time partly prevents
radiation of heat from the red hot coke against the sides of the expansion
chamber.
The mixing continues in a cylindrical passage D connecting the combustion
chamber F with the expansion chamber G which is supplied with a volume of
gases under pressure and at an elevated temperature regulated by the position of
the distribution valve at Y.
This distribution valve is connected with a small piston loaded by a weight and by
a spring and working in a cylinder M connected by a small tube m with the chamber
or reservoir R. Each degree of pressure between certain fixed limits corresponds
with a different position in which the piston in the cylinder M is in equilibrium.
When the pressure falls in the reservoir R, the piston yielding to the action of the
counterweight and spring tends to descend and alter the position of the distributer in
such a manner as to increase the proportion of air which passes through the fuel and
thus raises the working temperature.
The reverse takes plate when the pressure approaches the maximum limit assigned
to it. After the valve S has closed the air introduced into the expansion chamber and
that contained in the combustion chamber increase in volume continuing to force up
the motor piston and thus perform work by expansion at the expense of their internal
heat and of the heat generated in the fuel. At the end of the upward
stroke of the piston, an exhaust valve S', similarly arranged to the valve S,
opens, and the air in the expansion chamber falls to atmospheric pressure and
expelled being driven into the heater by the descent of the piston. The air thus
expelled proceeds from the box of the valve S¹ to a chamber Z in the heater through
a bent tube T, Figures 2 and 5 at a temperature more or less elevated according to
the working of the engine.
At the further extremity of the heater the exhaust gases which have been cooled to
about 210 degrees Centigrade are collected in a chamber Z, whence they are discharged
into the atmosphere through a pipe W.
The metal casing of the combustion chamber can be detached from the expansion

page_text: chamber by unscrewing bolts b. The combustion chamber then rests upon small
wheels or rollers upon which it may be moved. This combustion chamber is thus
rendered portable which enables the fireproof lining to be repaired and kept in order
with the greatest facility.
At its lower part this chamber is provided with an opening closed by a tight fitting
door to facilitate lighting and cleaning. This door is provided on its inner side with
a firebrick which fits into and fills the hole in the lining of the combustion chamber.
An apparatus for the introduction of fuel during the working is provided in the side
of the expansion chamber furthest from the support.
This apparatus is illustrated at K Figures 1, 2 and 4. It consists of a chamber L
communicating with the atmosphere through a door p and with the expansion
chamber G through a door p₁. These doors are of metal and packed with asbestos
paper.
The door p is in the form of a flap hinged on an axis a a being pressed
against the orifice of the chamber L when closed, by means of a pivoted screw e
or other suitable device. The door or flap P₁ is operated by two flat bars y
Figure connected to links or levers and working against the sides of the feed
chamber. These bars and levers may work in contact with the fuel or they may
he protected or enclosed by a casing or covering of sheet metal suitably arranged.
The levers are fixed on a shaft passing to the exterior through an asbestos
packing and having a weighted lever Q fixed on its outer end. This weighted
lever serves to maintain the door p, normally closed.
In order to introduce a charge of fresh fuel into the combustion chamber by
means of this apparatus, the door p is first opened and the fuel is thrown into
the chamber L after which the door p is closed. It then suffices to raise the
weighted lever Q in order to open the inner door or flap p, and allow the fuel
to fall down the inclined passage which conducts it to the combustion chamber.
The expansion chamber G is arranged above the combustion chamber and is
connected at its upper part with the base of the working cylinder C. The said
expansion chamber is formed by a metallic casing lined with fire bricks to protect
the metal from the action of the flame and diminish the loss of heat.
The working or motor cylinder C is provided externally with ribs or projections
which serve to conduct or throw off into the atmosphere the heat which it receives
from the expansion chamber. This cylinder is attached to the body or base of
the engine by the broad plate hereinbefore referred to.
In this cylinder works a hollow motor piston P provided at its upper part
forming a trunk working in the turned portion of the cylinder with a packing of
asbestos and plumbago. Figures 4 and illustrate the piston with a packing of
this descripton formed by means of a rope of asbestos covered with plumbago
and coiled in a helix around the upper part of the piston which is somewhat
reduced in diameter for this purpose. A ring which can be adjusted by means
of nuts enables this packing to be compressed and expanded so as to compensate
for wear.
The connecting rod through which the motor piston acts on the beam B is
attached to the piston by a flexible blade or spring of metal . One extremity
of this blade is secured to the lower end of the connecting rod and the other extremity
is attached to a cross bar bolted to two projections cast on the inside of the piston
trunk and passing through an eye or opening formed in the connecting rod.
This mode of connection presents the following advantages. It obviates the friction
wear and necessity for lubrication of a joint in a place inconvenient of access and
exposed to an elevated temperature. The connecting rod terminates at its upper
extremity in a bearing which is attached to it in such a manner that the connection
between the connecting rod and the beam presents two axes at right angles to one
another.
This arrangement is adopted in all the joints of the other connecting rods in the
motor the object being to allow for the distortion arising from unequal expansion and

page_text: contraction of the supports and moving parts and obviate the straining of the
connections and disturbance of the fitting that would otherwise be liable to be
produced by this cause.
The crank shaft carries the following parts viz.-a fly wheel y an exhaust cam J, an
admission cam J and a toothed wheel J2 driving a centrifugal governor O.
The exhaust cam J, operates the corresponding valve through the intervention of
a bellcrank lever and a connecting rod I₁ (fig. 2) working a second bell crank lever.
The admission cam J (Figures 1, 2 and 5) is so arranged as to enable the admission
or supply of air to the combustion chamber to he regulated or controlled in such a
manner as to maintain a uniform speed notwithstanding variations in the load or work
performed. The lifting part of the cam is formed along a generating line of the
cylinder forming the cam figs. 1 and 2 so that the valve S is invariably opened when
the crank shaft is in a certain position. The drop of the cam on the other hand is in
the form of a portion of a helix so that the length of the period of admission varies
according to the relative position of the cam and a small roller at the end of a lever N
operating the valve S by the intervention of a rod I and a lever N¹.
The speed of the engine is maintained between certain predetermined limits by the
action of a centrifugal governor O which automatically increases or diminishes the
period of admission according to the requirements of the motor by shifting
the lever N along the cam by the action of moveable weights O' fig. 6. hinged at 0.
The axis of this lever N is formed by a screw (Figure 6) which works in the
boss of the lover as in a nut. This screw is provided at one extremity with a friction
disc o placed between two plates a connected together. These two plates rotate with
the governor spindle and are capable of sliding longitudinally thereon when acted on
by a rod i connected to the governor balls or weights 0¹. So long as the speed keeps
within the prescribed limits these plates are held out of contact with the disc o but
when on the contrary the speed atlains the higher or lower limit the weights 01
displace the rod i and the disc o is caused to engage with one or the other of the
plates and the screw rotates on its axis so as to displace the lever N in the direction
required to restore the normal action of the engine.
2
When from any cause whatever the engine running at a speed below the fixed
limit would be liable to cause the lever N to be screwed hard up at the end of the
screwed axis this inconvenience is prevented by a small stop lever n figs. 7 & 8,
which being acted on by the lever N raises the plates a and throws them out of
gear with the disc o.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed 1 declare that what
I claim is
1. The general construction arrangement and combination of parts constituting
a new or improved hot air engine or aerothermic motor substantially as herein-
before described and illustrated in the accompanying drawings.
2. In a hot air engine or aerothermic motor, the combination of a pump and
a reservoir or chamber containing air under pressure a heater heated by the
exhaust gases and a distribution system as hereinbefore described with a remove-
able combustion chamber placed directly under a cylinder or expansion chamber
substantially as hereinbefore described and illustrated in the accompanying
drawings.
3. In a hot air engine or aerothermic motor the employment of mechanism for
automatically regulating the proportionate quantity of air supplied at the upper
and lower part of the combustion chamber according to the pressure in the air
reservoir or compression chamber substantially as hereinbefore described and
illustrated in the accompanying drawings.
4. In a hot air engine or acrothermic motor the employment, for automatically
increasing or diminishing the admission period, of a centrifugal governor operating
as herein before described with reference to the accompanying drawings.

page_text: 5. In a hot air engine or aerothermic motor the combination of the automatic
regulating mechanism and the governor whereby the action of the engine is
controlled independently of the work done by the engine substantially as herein-
before described and illustrated in the accompanying drawings.
6. The special arrangements of parts constituting the hot air engine or
aerothermic motor hereinbefore described with reference to the accompanying
drawings.
7. In the construction of hot air engines or aerothermic motors the combination
of the portable or moveable combustion chamber hereinbefore described with the
charging or feeding apparatus and motor cylinder substantially as hereinbefore set
forth and illustrated in the accompanying drawings.
8. The special arrangements of the moveable furnace capable of being readily
taken apart substantially as hereinbefore described with reference to the
accompanying drawings.