IMPROVEMENTS IN CALORIC OR HOT AIR ENGINES
Year: 1882

page_text: LETTERS PATENT to Matthew Piers Watt Boulton of Tew Park in the County
of Oxford and Edward Perrett of No 8, Victoria Chambers Westminster in
the County of Middlesex, for an invention of IMPROVEMENTS IN CALORIC OR
HOT AIR ENGINES
PROVISIONAL SPECIFICATION left by the said Matthew Piers Watt
Boulton & Edward Perrett at the Office of the Commissioners of Patents
on the 14th April 1882.
MATTHEW PIERS WATT BOULTON of Tew Park in the County of Oxford and
EDWARD PERRETT of No 8 Victoria Chambers Westminster in the County of
Middlesex, "IMPROVEMENTS IN CALORIC OR HOT AIR ENGINES
"
This invention relates to apparatus for heating air or elastic fluid used to work
Caloric or Hot Air Engines. In engines of this description if the heater is heated
by means of an external fire the metal of the heater is apt to be destroyed or
injuriously affected by the heat while if the fire is internal and maintained at high
pressure, the air needed for combustion has to be forced into the furnace at high
pressure, which in many cases entails disadvantage. The object of this invention
is to obviate these difficulties.
We provide a vessel of suitable shape capable of withstanding internal pressure;
a cylindrical vessel with domed ends is suitable for the purpose. This vessel is
partly filled with fire-bricks or other suitable material, laid with spaces between
them as is done in the vessels called regenerators, and also in vessels used for Hot
Blast Stoves. Also within the vessel is provided a furnace, in which the fuel,
either solid or liquid or gaseous is to be burnt as is done in Hot Blast Stoves.
The vessel is provided with suitable inlets for the introduction of the fuel and the
air needed for combustion, and also with an outlet for the products of combustion,
which pass away after they have heated the fire-brick or material within the
vessel. Means are provided by which these openings can be hermetically closed
when desired. The vessel is also provided with other inlet and outlet passages by
n....ll

page_text: which when desired it can be put in communication with a Caloric or Hot Air
engine, so as to serve for its heater.
The fire within the vessel is lighted and combustion maintained within it, this
combustion taking place as in ordinary furnaces, at or near the atmospheric
pressure. When this combustion has been maintained for a sufficient time, so that
the fire-brick or other material within the vessel has become sufficiently heated,
the inlets and outlets used for the purpose of this combustion are closed, and the
other passages connecting the vessel with the caloric engine are opened, so that the
communication between the vessel and the engine is or may be governed by valves
in the manner desired for the purposes of the engine. The heat stored in the
fire-brick serves to work the engine for a considerable time.
In order to obtain continuity of action we provide two or more vessels as already
described. These vessels instead of having a furnace each may be connected by
suitable flues to a common furnace or furnaces, which can be shut off when required.
Thus there may be one vessel supplying heat to the engine, whilst the others may
be receiving heat from the furnaces.
-Heating-apparatus such as above described may be used in conjunction with
various known forms of Caloric or Hot Air engines. -It-may-be used_with those
in which a regenerator is employed which is heated by the exhaust-and..imparts
heat to the working air-or with those in which such a regenerator is dispensed
with.
If the engine discharges warm exhaust into the air, this warm exhaust or a
portion of it may be used-to-supply air to the fire. If a refrigerator or cooling
vessel is used with the cugine, and the exhaust discharged into this, then on its..
way to the cooling 'vessel it may impart heat to suitable apparatus which heats
-air-used to supply_the fire.
When heating apparatus of the naturo above-described-is-used as the heater of a
Caloric or Hot Air engine, it may be convenient to employ a separate furnace or
separate furnaces to heat the hot portion of the cylinder or cylinders employed in
the engine, and the products of combustion passing away from such furnace or
furnaces may be employed to impart some heat to the supply of working air on its
way to the main heater.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Matthew Piers Watt Boulton & Edward Perrett in the Great
Seal Patent Office on the 13th October 1882.
MATTHEW PIERS WATT BOULTON of Tew Park in the County of Oxford and
EDWARD PERRETT of No 8 Victoria Chambers Westminster in the County
of Middlesex "IMPROVEMENTS IN CALORIC OR HOT AIR ENGINES"
This Invention relates to apparatus for heating air or elastic fluid used to work
Caloric or Hot air engines. In engines of this description, if the heater is 'heated
by means of an external fire, the metal of the heater is apt to be destroyed or
injuriously affected by the heat while if the fire is internal and maintained at high
pressure, the air needed for combustion has to be forced into the furnace at high
pressure, which in many cases entails disadvantage. The object of this invention
is to obviate these difficulties.
We provido a vessel of suitable shape, capable of withstanding internal pressure;
a cylindrical vessel with domed ends is suitable for the purpose. This vessel is
partly filled with fire-bricks or other suitable material, laid with spaces between
them, as is done in the vessels called regenerators and also in vessels used for Hot
Blast Stoves. Also within the vessel is provided a furnace, in which the fuel,
either solid or liquid or gaseous, is to be burnt as is done in Hot Blast Stoves. The
vessel is provided with suitable inlets for the introduction of the fuel and the air
needed for combustion, and also with an outlet for the products of combustion,
which pass away after they have heated the fire-brick or material within the
vessel. Mcans are provided by which these openings can be hermetically closed
when desired. The vessel is also provided with other inlet and outlet passages
by which when desired it can be put in communication with a Caloric or Hot Air
engine, so as to serve for its heater.
The fire within the vessel is lighted and combustion maintained within it, this
combustion taking place as in ordinary furnaces, at or near the atmospheric
pressure. When this combustion has been maintained for a sufficient time, so that
the fire-brick or other material within the vessel has become sufficiently heated,
the inlets and outlets used for the purpose of this combustion are closed, and the
other passages connecting the vessel with the caloric engine are opened so that
the communication between the vessel and the engine is or may be governed by
valves in the manner desired for the purposes of the engine. The heat stored in
the fire-brick serves to work the engine for a considerable time.
In order to obtain continuity of action we provide two or more vessels as already
described. These vessels instead of having a furnace each may be connected by
suitable flues to a common furnace or furnaces, which can be shut off when
required. Thus there may be one vessel supplying heat to the engine, whilst the
others may be receiving heat from the furnaces. Heating apparatus such as above
described may be used in conjunction with various known forms of Caloric or Hot
air engines. It may be used with those in which a regenerator is employed which
is heated by the exhaust and imparts heat to the working air-or with those in
which such a regenerator is dispensed with.
If the engine discharges warm exhaust into the air, this warm exhaust or a
portion of it may be used to supply air to the fire. If a refrigerator or cooling
vessel is used with the engine, and the exhaust discharged into this, then on its
way to the cooling vessel it may impart heat to suitable apparatus which heats
air used to supply the fire.
When heating apparatus of the nature above described is used as the heater of
a Caloric or Hot Air engine it may be convenient to employ a separate furnace or

page_text: Fig. 1 is a vertical section of a hot air engine combined with a single heating
vessel according to our invention. A is the vessel within which is formed a firo-
place B that can be closed air tight by a door C. The interior of the vessel is
charged with fire-bricks arranged to form a central flue band a number of inter-
stitial passages to a pipe D which by means of a cock or valve E can be put in
communication either with a chimney For with the cylinder G of the engine.
The hot air engine shewn is of a well known kind having a cylinder G fitted with
a differential piston H. The upper part of the cylinder is arranged as a pump
with inlet and outlet valves g' and g³, and in the lower part of the cylinder the
heated air acts, being admitted by a valve h¹ and discharged by a valve k², both
which valves are worked by eccentrics or cams on the engine shaft For several
hours, while the engine is at rest, the door C is open and the cock or valve E is
set so as to put D in communication with F. A fire being then kindled in B, the
flame and hot products of combustion ascend the central flue band descend through
the interstices of the fire bricks, finally passing by the pipe D to the chimney F.
When the fire-bricks have been sufficiently heated, the door C is hermetically
closed, and the cock or valve E is moved so as to close communication with F and
put in communication with the valve g The engine being then started by
turning the flywheel, air is drawn in by the valve g' and is delivered by g* to the
pipe-D. It descends this pipe and rising through the interstices of the fire-bricks
becomes heated; the air thus heated is admitted by the valve to the cylinder G
in which it expands propelling the piston H, and having performed work it is
discharged by the valve . When the engine has worked for several hours, a
great part of the accumulated heat having been abstracted from the fire-bricks,
the engine is stopped, and they are again heated. For many ordinary purposes,
this alternative action of one vessel A. suffices. For example the heating may
be effected during tho night when the engine power is not required, and suflicient
heat may be thus stored up to keep the engine working through the day. When,
however, continuous action of the engine is required, as for example for marino
propulsion, at least two heating vessels should be provided. These may be arranged
as shown by Fig. 2 which is a longitudinal section of one of them, and Fig. 3
which is a plan of both. While the heat is being accumulated in the one vessel A
the doors Cand Care open, also the valve E2 in the pipe leading to the chimney F,
but the valves K and L² communicating with the engine are closed, and a fire
being kindled in B the flame and hot products of combustion pass through the
interstices of the bricks to the pipe D and escape by the chimney F. When
sufficient heat has been accumulated, the doors C, Carc hermetically closed, also
the valve E is closed and the valves K and L* are opened. The air or fluid is
then sent from the engine through the valve K and passing through the inter-
stices of the bricks becomes heated and passes to the engine by the valve L² In a
similar manner the other vessel A' is worked alternating with A², so that while
the one is receiving heat from the fire. the other is imparting heat to the air or
fluid that works the engine.
Obviously the apparatus and method of operating which we have described may
be applied to caloric engines of various kinds, whether they have regenerators or
not, and whether they are worked with air or fluid at low or at high pressure.
In cases where the exhaust discharged from the working cylinder is warm, it may
be employed to supply B the heating fire or to heat the air supplied to the fire.
When two or more heaters are employed, it is in some cases advantageous to use

page_text: a portable fire place or furnace which can be transferred from one of the heaters
to another.
It is also of advantage to provide the pipes which conduct the air to and from
each heater with a by-pass governed by a cock or valve, so that the heated air can
be tempered on its way to the engine by admitting a greater or less quantity of
the cold air to mix with it.
Having thus described the nature of our invention and in what manner the
same is to be perforined, we hereby declare that we make no general claim to
working a heater alternatively as above described, as such heaters are used in this
manner for heating the air blast for sinelting, and other furnaces, but we claim :—
The combination of a hot air or caloric engine with an alternatively acting heater
constructed and arranged substantially as herein described.
In witness whereof I the said Matthew Piers Watt Boulton have hereunto set
my hand and seal this tenth day of October in the year of our Lord, one
thousand eight hundred and eighty two.