Improvements in Hot Air Engines.
Year: 1896

page_text: Date of Application, 29th Sept., 1896
Complete Specification Left, 29th June, 1897-Accepted, 31st July, 1897
Improvements in Hot Air Engines.
I CAMILLE ALPHONSE FAURE of 37 Avenue de la Republique Paris in the Republic
of France Engineer do hereby declare the nature of this Invention to be as follows:-
My Invention relates to hot air engines wherein the saine supply of compressed air
is used over and over again being transferred successively from one receiver to another
the said air being heated and dilated or cooled, and contracted alternately.
The improved engine is of the Ericson type, comprising a cold and a hot cylinder
the piston connecting rods being connected to two cranks at right angles to each
other; the said cylinders being in constant communication with each other and the
cranks enclosed in the air space of the engine.
The operation of the engine is due to the contraction of the hot air within the
"cold" cylinder and its transfer to and expansion in the "hot" cylinder; and its
conveyance hack to the "cold" cylinder.
The chief drawback of such engines, as hitherto constructed, is due to their small
"yield" of available power and to their great weight relatively to their power.
It has been attempted to utilize the principle, as well as the simplicity of con-
struction of this type of engine, whilst enhancing its value by preparatory compression
of the air so that the engine works in an atmosphere of normally high pressure, say
a pressure of 140 lbs. per square inch the working capacity being correspondingly
increased.
Certain precautions are necessary to enable the principles above stated to be carried
out in practice.
Leakage of air both from the machine and internally past the pistons and generally
whatever may tend to reduce the power and efficient practical working of the engine
must be prevented and the heating and cooling surfaces should be extended so that
the greatest amount of work can he obtained from a given heat.
In an engine constructed according to my Invention the cylinders may be similar
in general form the "hot" cylinder being provided with means for heating it, and
the "cold" cylinder being provided with means for cooling it.
The cylinders are in permanent communication with each other at the bottom, by
a passage or passages preferably integral therewith and connected so as to form an
airtight space to retain the air, which is beneath the pistons. At the upper part the
cylinders are connected by a passage or passages also preferably formed integral
therewith and connected so as to form an air tight space to retain the air above the
pistons.
It is important that the passive resistances or strains upon the journals and crank
shaft of the engine should be reduced as much as possible and for this purpose the
connecting rods and crank shaft are mounted in ball bearings. The work performed
within the engine is transmitted externally through a separate shaft, which receives
motion from a crank, somewhat loosely connected to the inain crank shaft.
The said separate shaft is preferably inade of strong steel and of small dimensions

page_text: and is passed through a stuffing box in the side of the engine and is also supported
by an external bearing. Upon this separate shaft, the fly wheel is mounted, which
fly wheel is provided with vanes so that it acts as a ventilating disc it being enclosed
in a casing; the air currents produced being conducted to the fire-box or furnace
which heats the "hot" cylinder, being led into and diffused within a casing
surrounding the said fire-box or furnace.
Inverted U shaped pipes in both cylinders are let into the upper end thereof so
that the air passes down and then up these tubes and afterwards passes through a space
containing cylindrical rods or other forms of some material such as porcelain. These
greatly assist the heating and cooling of the air during its flow towards the hot
cylinder or the cold cylinder, as the case may be, acting as heat restorers. The afore-
said inverted U shaped pipes, can be formed in the casting of the cylinders themselves
by inserting into the cylinder moulds bent steel tubes of the desired shape and they
constitute numerous narrow channels all around the cylinders and allow the outward
temperature of the cylinders to thoroughly permeate the material and to be diffused.
over the whole of the inner surfaces of the air channels. These features of construction
are of paramount importance inasmuch as they enable a most effective contact to take
place between the air and the heated or cooled surfaces; which fact, added to the
density of the circulating air, considerably enhances, the efficacy of the internal
henting surface.
The cooling of the cold cylinder is conveniently effected by water passed through a
surrounding casing or jacket or a current of air may be used and this may be supplied
from the fan constituted by the fly wheel.
The heating surface around the hot cylinder may be constituted by an annular set
of ports which may be formed in the process of casting the cylinder itself and into
these ports heat retaining rods or the like may be passed.
Through these ports there passes a flame produced in any suitable furnace or fire
place, say a petroleum furnace which is in the casing surrounding the hot cylinder
and is surrounded by a perforated wall and contains a helical trough into which
petroleum is supplied from a pipe or pipes controlled by a tap or taps the combustion
of the petroleum being supported by the blast supplied from the fan constituted by
the fly wheel. Or petroleum gas may be blown in or petroleum blow pipes may be
used.
The blast is properly distributed by the perforated wall which may contain short
nozzles acting as blow pipes which will cause the cylinder to be very effectually
heated. The admission of petroleum into the furnace may be controlled automatically
by a tappet rod acting on the tap or taps the said tappet rod being operated at the
proper times by a tappet on the fly wheel coming into contact with one or other of
the tappets on the said rod according to the position of the tappet on the fly wheel
which tappet is adapted to slide longitudinally upon say one of the spokes of the fly-
wheel under the influence of centrifugal force and so supply more or less petroleum
according to which of the tappets on the tappet rod it comes in contact with.
The
said tappet rod by the same movement, also regulates by a suitable valve, the channel
or port for air supplied to the furnace by the fan.
In view of the high internal pressures which are brought into play a slight leakage
or escape of air along the pistons of the cylinders would greatly reduce the power of
the engine, and greatly decrease its useful effect or "yield." This I prevent by sup-
plying the pistons with oil or other suitable liquid either constantly or whenever such
a supply becomes necessary in consequence of a leakage occurring this being
effected through a valve in a pipe or passage fitted to each cylinder. The lower part
of this passage dips into the liquid, a predetermined quantity of which has been
admitted into the lower part of the interior of the engine.
Should there be an escape of air through the pistons at a certain point of the
revolution the liquid will rise in the pipes or passages and will pass to the top of the
pistons. The reduction of the power of the motor, and speed regulation, are obtained
by the automatic rising of the said valve effected by a rod which is operated by
means of suitable levers from the aforesaid tappet shaft, Upon the said valve being

page_text: raised, air from the cold cylinder will pass into the space below the pistons, instead of
entering the hot cylinder; the speed of th engine being thus regulated.
Either at the outset, or as the occasion arises, the air is compressed in the engine
by means of a pump, which may be either hand-prated or automatic, and may be
fixed, for example, on to an orifice in the space below the cylinders; the suction or
exhausting action of the said pump being also utilise to draw lubricant from a cup
and pass it to the engine any lubricant which may escape through the packing of the
aforesaid separate shaft under the influence of the considerable internal pressure;
passing into the said cup a liberal supply of lubricant is furnished to the said
bearing by a cup which catches lubricant from the other parts of the engine so that
air-tightness is reliably ensured.
The engine herein described has been specially devised with a view to its employ-
ment in connection with motor-carriages or autocars; and it may be supported on
girders and be provided with a gear-wheel for transmitting motion to the running
wheels. It may, however, if desired, be employed as a stationary engine and be
heated with coal from a suitable furnace.
Dated this 20th day of September 1896
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
Improvements in Hot Air Engines,
I CAMILLE ALPHONSE FAURE, of 116 Boulevard Richard Lenoir, Paris, in the
Republic of France, Engineer, do hereby declare the nature of this Invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My Invention relates to hot air engines wherein the same supply of compressed
air is used over and over again being transferred successively from one receiver to
another the said air being heated and dilated or cooled and contracted alternately.
The improved engine is of the Ericson type, comprising a cold and a hot cylinder,
the piston connecting rods being connected to two cranks at right angles to each
other, the said cylinders being in constant communication with each other and the
cranks being enclosed in the air space of the engine.
The operation of the engine is due to the cooling and contraction of the hot
air within the cold cylinder; and its transfer to and heating and expansion in
the "hot" cylinder; and its conveyance back to the "cold" cylinder and so on
alternately.
The chief drawback of such engines as hitherto constructed is due to their sinall
yield of available power and to their great weight relatively to their power.
It has been attempted to utilize the principle as well as the simplicity of
construction, of this type of engine, whilst enhancing its value by preparatory
compression of the air so that the engine works in an atmosphere of abnormally high
pressure, say, a pressure of 140 lbs. per square inch, the working capacity being
thereby correspondingly increased.
Certain precautions are necessary to enable the principles above stated to be carried
out in practice.
Leakage of air both from the machine and internally past the pistons and
generally whatever may tend to reduce the power and efficient practical working of
the engine must be prevented and the heating and cooling surfaces should be
extended so that the greatest possible. amount of work can be obtained from a
given heat.

page_text: I will describe my invention with reference to the accompanying drawing, which
represents in vertical section, partly in elevation, an engine constructed according to
my invention. A and B are two cylinders provided with pistons C and D. These
cylinders and pistons may be similar in general form. A (shewn in section) is the
"hot" cylinder provided with means for heating it and B is the "cold" cylinder
(shewn in elevation) provided with means for cooling it.
The cylinders are in permanent communication with each other at the bottom by
a passage or passages in parts preferably integral with the cylinders respectively and
connected by bolts passed through the flanges A B so as to form an air tight
space to retain the air which is beneath the pistons; at the upper part, the
cylinders A and B are connected by a passage or passages in parts connected
to each cylinder and connected by bolts passed through the flanges A and B2
so as to form an air tight space to retain the air which is above the pistons.
The pistons C and D of the cylinders A B are provided with connecting rods E
and F connected to cranks E¹ Fi on the crank shaft G and at about 90 degrees to
each other.
Assuming by way of example that the initial pressure of the air in the upper
parts of the cylinders is 10 kilogrammes per square centimetre, it may happen that
the maximum pressure upon the upper side of the pistons during the working of the
engine and by the heating of such air, attains 50 kilogrammes per square centimetre,
and that notwithstanding the counter-pressure of air beneath the pistons, a very
powerful total thrust will still be exercised upon the pistons but the differential
useful effect obtained froin the engine will be but slight unless means are provided
for reducing the frictional resistances or strains upon the journals and crank shaft of
the engine. To effect this the connecting rods and the crank shaft are mounted in
hall or equivalent. bearings as shewn clearly in the drawing where the ball bearings
for the connecting rods are marked e and and the ball bearings for the shaft are
marked g.
The motion imparted to the crank shaft G (which is enclosed in an air tight casing
in communication with the cylinders as shewn) is transmitted to the exterior through
a separate shaft H which receives motion from the crank H 1 loosely connected to pin
of the crank E 1.
The shaft H is preferably made of very strong steel so that it can be of small
diameter and it passes through a stuffing box h in the side of the casing which
encloses the crank shaft and it is also supported by an external bearing . Upon this
separate shaft H the fly wheel I is secured which fly wheel is provided with vanes II so
that it acts as a fan, it being enclosed in a casing 12; the air currents produced by the
said fan being conducted through the passage 13 and valve 0 1 into the fire box or
furnace J which heats the hot cylinder A, the air so supplied being received and
diffused within a casing J 1 surrounding the said fire box or furnace J and thence
through the perforated wall into the said fire box or furnace. The wall is
preferably made of thick red copper in metallic contact with the cylinder A to keep
the heat from radiating outwardly and cause it to be conveyed at once to the said
cylinder. U shaped or equivalent passages are made in the upper end of each
cylinder, as shewn at A in the cylinder, A, so that the working air enclosed in
the cylinder, as distinguished from the air supplied by the fly wheel fan, passes
down and then up these passages and afterwards passes over the cylinder
top and through the perforated plate A4 and through the chest or
chamber A 2* and passage A 3 which form heat regenerators, the chest or
chamber A 2x containing cylindrical rods or other forms of some material such as
porcelain around which the air passes. These heat regenerators greatly assist the
requisite alteration in temperature of the air during its flow towards the hot cylinder
or the cold cylinder, as the case may be, in consequence of the great area of contact
surface which they offer to the said air and by reason of the density of the fluid in
motion. The U shaped passages A 5 and also those in the cylinder B can be formed
in the castings of the cylinders themselves by inserting bent steel tubes of the
requisite shape into the moulds in which the cylinders are cast. These U shaped

page_text: tubes constitute numerous narrow channels around the cylinders A and B and allow
the temperature applied to the cylinders to thoroughly permeate the material thereof
and to be diffused over the whole of the inner surfaces of the air channels thus
created. These features of construction are of paramount importance in as much as
they enable a most effective contact to take place between the air and the heated or
cooled surfaces, which fact added to the density of the circulating air, considerably
enhances the efficacy of the engine.
The cooling of the cold cylinder B is conveniently effected by water, passed
through a surrounding casing or jacket K as indicated by the arrows; or a current
of cool air may be used for the purpose and this may be supplied from the fan
constituted by the fly wheel by providing suitable passages to conduct air from the
easing I 2 to the casing K.
The heating surface around the cylinder A is shown as being increased by an
annular set of ports L which may be formed in casting the cylinder and into these
ports heat retaining rods L, or the like may be passed.
Flame or hot products of combustion produced in any suitable furnace or fire-
place, passes through the said ports L. The said furnace or fire-place may be a
petroleum furnace as is shewn in the drawing which is in the casing surrounding
the cylinder A and is enclosed by the aforesaid perforated wall and contains a
helical or other trough or holder for petroleum (such as is shewn at M) which
petroleum is supplied through the tube N (or tubes) controlled by a tap N. The
combustion of the petroleum is efficiently supported by the air supplied from the
fan constituted by the fly wheel; or petroleum gas may be blown in, or petroleum
blow-pipes may be used, or in fact any other means for heating which may be
convenient or suitable.
The blast of air is properly distributed by the perforated wall ; which may
contain short nozzles as shewn at 2 acting as blow-pipes which will cause the
cylinder A to be very effectually heated notwithstanding its comparatively small
outer surface.
The admission of petroleum into the furnace J may be controlled automatically
by a tappet rod O connected with the tap N', the said tappet rod being operated, at
the proper times by a tappet 04 on the fly wheel coming into contact with one or
other of the tappets 02 secured to the said rod O according to the position of the
tappet 04 on the fly wheel which tappet. 04 is secured to a block P sliding
longitudinally say upon one of the spokes of the fly wheel I, under the influence of
centrifugal force and being returned to its normal position by a spring as illustrated
clearly in the drawing.
In this way more or less petroleum is supplied to the furnace according to the speed
of the engine.
The said tappet rod O by the same movement also regulates the valve 1 to supply
the requisite quantity of air from the fan side to the furnace, the said valve 01 being
secured to the rod O.
In view of the high internal pressures which are brought into play during the
action of the engine a slight leakage or escape of air past the pistons of the cylinders
A and B would greatly reduce the power of the engine, and decrease its useful effect
or yield. This prevent by supplying the pistons with oil or other suitable liquid
(which I will refer to as oil) either constantly or automatically whenever such a supply
becomes necessary in consequence of a leakage of air occurring; this being effected
through a valvey and pipes q' leading into the upper end of each cylinder. The
lower jassage g from the valve box of the valve 9 dips into the oil, a quantity of
which is placed in the lower interior space of the engine by the opening at q'; by the
operation of the pistons themselves, when the pressure at the upper ends of the
cylinders is at the minimum at each revolution, should there have been an escape of
air through the pistons during the period of maximum pressure, so that a partial
vacuum forms, at the moment of maximum extension, then the oil will rise in the
pipes q' and will pass to the tops of the pistons and prevent leakage of air.
The reduction of the power of the motor, and speed regulation are obtained by

page_text: raising the said valve q (or another similar valve specially provided for the purpose
so that there is a valve for the oil and another for the air) by a rod r which is
operated by means of levers 1 2 03 from the tappet shaft O by the crank O* as
shewn.
Upon the valve q being raised, air from the cold cylinder B will pass into the space
below the pistons instead of entering the hot cylinder A; the speed of the engine
being thus regulated. Another office of the valve q is in starting the engine, the said.
valve is by a suitable hand attachment lifted during the period of compression and
lowered at the moment the air is transferred from the cylinder B to the cylinder A
so that the engine derives a small power from the expansion of the air but not from
compression. This power is sufficient to cause the speed to increase gradually (no
load then being on the engine). The said valve q acts regularly when the proper
momentum is imparted to the fly wheel.
Either at the outset, or as occasion arises, the air is compressed in the engine by
means of a pump, (not shewn in the drawing) which may be either operated by hand
or by the engine itself and may be fixed, for example on to the orifice S; the suction
or exhausting action of the said pump being also utilized to draw oil from a cup S 1,
by means of the pipe S 2 so as to return to inside the engine the oil which may have
escaped through the packing G under the influence of the considerable internal
pressure; a liberal supply of which oil has been passed to the said packing by a
cup which catches oil from the other parts of the engine, so that air-tightness
is reliably ensured.
The engine herein described has been especially designed for employment in
connection with motor-carriages or auto-cars; and it is shewn as being supported by
girders T and the shaft H is provided with a gear-wheel V for transmitting motion
to the running wheels. It may, however, if desired, be employed as a stationary
engine and be heated by means of coal, or other fuel from a furnace in any convenient
position.
Having now particularly described and ascertained the nature of this
invention and in what manner the same is to be performed, I declare that
what I claim is :-
1. In hot air engines the combination with two cylinders communicating with each
other above and below the pistons thereof, of casings or jackets surrounding the said
cylinders and means for applying a heating agent to the casing or jacket of one
cylinder, and a cooling agent to the casing or jacket of the other cylinder, substantially
as hereinbefore described.
2. In hot air engines the combination with two cylinders communicating with
each other above and below the pistons thereof, of means for heating the one and
cooling the other and channels such as A³ for the passage of the air on its way from
cylinder to cylinder substantially as herein before described.
3. In hot air engines the combination with two cylinders communicating with
each other above and below the pistons thereof, of means for heating the one
and cooling the other, and chambers such as A containing porcelain rods or
other equivalent devices for acting as regenerators, substantially as herein before
described.
4. In hot air engines the combination with two cylinders communicating with
each other above and below the pistons thereof, of casings or jackets surrounding
the said cylinders and means for supplying a cooling medium to the one and a
petroleum furnace enclosed in the other, substantially as hereinbefore described.
5. In hot air engines the combination with two cylinders communicating with
each other above and below the pistons thereof, of cases or jackets surrounding the
said cylinders and means for supplying a cooling medium to the one and a petroleum
furnace enclosed in the other, and a fly wheel provided with vanes to constitute a fan
for passing air into the said furnace, or around the cold jacket, substantially as
hereinbefore described.
6. In hot air engines with two cylinders in communication above and below the

page_text: pistons thereof, and provided with means for heating and cooling them respectively,
a valve such as q controlling a passage or passages for oil or other suitable liquid to
the tops of the pistons, substantially as herein before described.
7. In hot air engines with two cylinders in communication above and below
the pistons thereof, and provided with means for heating and cooling them
respectively, a valve such as q controlling a passage from above the piston of the
cold cylinder to beneath the pistons of the cylinders, and a governor and means
for causing it to act on the said valve to regulate the speed substantially as
hereinbefore described.
8. In hot air engines two cylinders provided with means for heating and cooling
them respectively, and in communication with each other both above and below the
pistons, the space by which they communicate below the pistons, enclosing cranks at
or approximately at right angles to each other, or equivalently worked relatively to
each other, from which motion is conveyed to outside the engine, substantially as
hereinbefore described.
9. In hot air engines the combination with two communicating cylinders and
means for heating the one and cooling the other of a crank shaft mounted in ball or
equivalent bearings and with ball or equivalent bearings between the cranks and the
connecting rods, substantially as herein before described.
10. In combination with an auto-car, an engine comprising two communicating
cylinders with means for heating and cooling them respectively, and cranks in the
enclosed space by which the cylinders communicate beneath the pistons, and means
for conveying the motion of the said cranks to outside the engine and to the running
wheels of the vehicle, substantially as hereinbefore described.
11. A hot air engine consisting of, or comprising two cylinders communicating
with each other both above and below the pistons thereof, means for heating the one
cylinder and cooling the other, cranks in the communicating space below the pistons,
means for conveying the motion of the said cranks to outside the engine, means for
supplying oil or the like to above the pistons and for passing air from above the
piston of the cold cylinder to the space below the pistons for securing air-tightness,
lubrication, and speed regulation all substantially as hereinbefore described.
Dated this 29th day of June 1897.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.