IMPROVEMENTS IN COMPRESSED AIR MOTORS
Year: 1873

page_text: LETTERS PATENT to Edward Thomas Hughes, of the Firm of Hughes
and Son, Patent Agents, 123, Chancery Lane, London, for the In-
vention of "IMPROVEMENTS IN COMPRESSED AIR MOTORS." -A communi-
cation from abroad by Henry Bushnell and Elias Parmelee Merri-
man, both of New Haven, in the County of New Haven, in the
State of Connecticut United States of America.
Sealed the 21st November 1873, and dated the 22nd May 1873.
PROVISIONAL SPECIFICATION left by the said Edward Thomas
Hughes at the Office of the Commissioners of Patents, with his
Petition, on the 22nd May 1878.
I, EDWARD THomas Hughes, of the Firm of Hughes and Son, Patent
Agents, 123, Chancery Lane, London, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN COMPRESSED AIR MOTORS," a
communication to me from abroad by Henry Bushnell and Elias
Parmelee Merriman, both of New Haven, in the County of New Haven,
in the State of Connecticut, United States of America (to be as
follows):-

page_text: It is well known that air and other fluids compressed increase the
temperature in proportion to the compression, but after standing or
cooling the temperature is proportionately reduced. As the compressed
air in the reservoir is usually about the same temperature as tho sur-
rounding air it follows that when the compressed air is allowed to escape
into the atmosphere it expands so rapidly as to reduce its temperature to
such an extent as to cause the moisture in the escaping air to crystallize;
and in engines which use this compressed air or fluid this crystallizing
or freezing causes a great inconvenience and renders the use of high
pressures impracticable. To overcome this difficulty is the object of this
Invention, and it consists in injecting into the escape from the engine a
jet of hot air sufficient to prevent the freezing before mentioned.
The best method of carrying out this Invention is illustrated in the
accompanying Drawings, where Fig. 1 represents a top or plan view;
Fig. 2, a side view, a portion of the jacket in both Figures broken away
to show the interior; Fig. 3, a section on line x, x.
A is the cylinder, denoted in solid black, Fig. 3, constructed in sub-
stantially the usual manner for steam cylinders, the exhaust or outlet
represented at B, and b, the valve chamber. Around the cylinder is
placed a jacket C, which forms a chamber D between the said jacket
and cylinder, as seen in Fig. 3. Into this chamber from a suitable air
pump E, worked by the said engine or other power, a tube F leads and
forces air into the chamber D. In connection with the chamber a
pressure valve H is arranged, into which through an opening c air from
the chamber passes beneath the piston a, the said piston having a spring
or its equivalent above graduated to the pressure required, and to this
valve or cylinder H and above the opening c a second opening d is made
into a tube L, which leads up into the exhaust passage N, so that air
passing from the chamber D through the valvo H flows directly through
the tube L to the exhaust opening B.
In operation the air pump forces air into the chamber D, thence to
the valve H, until the piston a rises sufficiently high to allow the air to
escape. As this time the air has been sufficiently compressed to attain
the requisite degree of heat, and in this heated state passes directly into
the exhaust passage from the cylinder A, raises the temperature of such
escaping air sufficiently to prevent its freezing, and thus avoid the

page_text: difficulty which usually attends the employment of air and similar fluids
under pressure as a motive power.
As but a small quantity of heated air is necessary the air pump may
be very small in comparison to the cylinder A.
In case the pressure within the chamber D becomes greater than that
within the cylinder we provide a valve f, which opens into the valve
chamber b, so that the air in the chamber D under greater pressure
than that in the cylinder will open the valve f and pass into the valve
chamber.
It may be desirable at times that this heated air pass into the valve
chamber in order to warm the air or to prevent the sticking of the
valves, and this will occur by means of this valve f, because when the
slide valve is open to allow the air to pass into the cylinder A the
pressure upon the under side of the valve fis to a great extent removed.
At that time the hot air from the chamber D will pass directly into the
valve chamber b, but this will only occur when the air is passing freely
into the cylinder A, the valve f closing so soon as or sooner than the
slide valve closes. While this construction is believed to be the best for
the purpose named it may be accomplished without the jacket or
chamber around the cylinder, the object of this Invention being
accomplished by the injection of hot air into the passage from the
cylinder.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Thomas Hughes in the Great Seal Patent
Office on the 22nd November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
THOMAS HUGHES, of the Firm of Hughes and Son, Patent Agents, 123,
Chancery Lane, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of May, in the year
of our Lord One thousand eight hundred and seventy-three, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Edward Thomas Hughes, Her special
licence that I, the said Edward Thomas Hughes, my executors, admin-

page_text: istrators, and assigns, or such others as I, the said Edward Thomas
Hughes, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN COMPRESSED AIR MOTORS," (a communication to me from
abroad by Henry Bushnell and Elias Parmelee Merriman, both of New
Haven, in the County of New Haven, in the State of Connecticut,
United States of America) upon the condition (amongst others)
that I, the said Edward Thomas Hughes, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of
their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Edward Thomas Hughes, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, that is to say :-
This Invention relates to improvements in that class of engines which
are driven by compressed air or other gaseous medium.
It is well known that air and other fluids compressed increase the
temperature in proportion to the compression, but after standing or
cooling the temperature is proportionately reduced. As the compressed
air in the reservoir is usually about the same temperature as the sur-
rounding air it follows that when the compressed air is allowed to escape
into the atmosphere it expands so rapidly as to reduce its temperature to
such an extent as to cause the moisture in the escaping air to crystallize,
and in engines which use this compressed air or fluid this crystallizing or
freezing causes a great inconvenience and renders the use of high
pressure impracticable. To overcome this difficulty is the object of
this Invention, and it consists in injecting into the escape from the
engine a jet of hot air sufficient to prevent the freezing before men-
tioned.
The best method of carrying out this Invention is illustrated in the

page_text: Figure 2, a side view, a portion of the jacket in both figures broken away
to show the interior; Figure 3, a section on line x, x.
A is the cylinder denoted in solid black, Figure 3, constructed in sub-
stantially the usual manner for steam cylinders, the exhaust or outlet
represented at B, and 6 the valve chamber. Around the cylinder is
placed a jacket C, which forms a chamber D between the said jacket and
cylinder, as seen in Figure 3. Into this chamber from a suitable air
pump E, worked by the said engine or other power, a tube F leads and
forces air into the chamber D. In connection with the chamber a
pressure valve H is arranged, into which through an opening c air from
the chamber passes beneath the piston a, the said piston having a spring
or its equivalent above graduated to the pressure required; and to this
valve or cylinder H and above the opening c a second opening d is made
into a tube L, which leads up into the exhaust passage N, so that air
passing from the chamber D through the valve H flows directly through
the tube L to the exhaust opening B.
In operation the air pump forces air into the chamber D, thence to
the valve H, until the piston a rises sufficiently high to allow the air to
escape. At this time the air has been sufficiently compressed to attain
the requisite degree of heat, and in this heated state passes directly into
the exhaust passage from the cylinder A, there mingling with the com-
pressed air escaping from the cylinder A, raises the temperature of such
escaping air sufficiently to prevent its freezing, and thus avoid the
difficulty which usually attends the employment of air and similar fluids
under pressure as a motive power.
As but a small quantity of heated air is necessary the air pump may
be very small in comparison to the cylinder A.
In case the pressure within the chamber D becomes greater than that
within the cylinder I provide a valve f which opens into the valve
chamber 6, so that the air in the chamber D under greater pressure
than that in the cylinder will open the valve ƒ and pass into the valve
chamber.
It may be desirable at times that this heated air pass into the valve
chamber in order to warm the air or to prevent the sticking of the valve,
and this will occur by means of this valve f, because when the slide
valve is open to allow the air to pass into the cylinder A the pressure