AN IMPROVED COMBINED STEAM AND AIR ENGINE
Year: 1878

page_text: '
PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 17th January 1878. A com-
munication from abroad by Edward Magruder Strange and Frederick Rudolph
Schettler, both of the City, County, and State of New York, United States of
America.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "AN IMPROVED COMBINED STEAM AND AIR ENGINE." [A com-
munication from abroad by Edward Magruder Strange and Frederick Rudolph
Schettler, both of the City, County, and State of New York, United States of
America.]
This Invention relates to an improved motor, and consists mainly in the use of a
mixture of steam and atmospheric air, the latter being first compressed in a single
or double acting steam cylinder or in a separate compressor, and then mingled with
the steam above the mass or bulk of water in the boiler. This air and steam
mixture is then employed as the expansive medium in driving the piston of the
engine, so as to overcome the greater resistance occassioned by the compressed air.
The steam cylinder of the engine, if single-acting, is provided with a steam supply
port and valve that furnishes steam from the boiler so as to move the piston in one
direction, and at the return of the piston the steam is exhausted through an exhaust
port whose valve opens at the commencement of the return stroke, but closes as
soon as the supply port is opened for the admission of steam from the
boiler.
In the opposite head of the single-acting cylinder is arranged an air port and
valve that admit atmospheric air from the outside with the return stroke of the
piston, while, with the forward stroke of the piston, the volume of air admitted is
compressed and forced through a valve and exit port, and through an air pipe to
the lower part of the boiler, where it passes to the inside of the same, and is
distributed by a perforated diaphragm near the bottom of the boiler, so as to be
sprayed in bubbles through the bulk of the water in the boiler and break up the
same, making it more ready to be transformed into steam by the heat of the boiler
furnace.

page_text: The upper part of the boiler is connected by a steam pipe to the steam supply
port or ports of the engine.
In case a double-acting engine and compressor is used, the steam supply and
exhaust ports, as well as the air entrance and exit ports, have to be arranged in
each cylinder head, or the engine may be separated from the compressor by
extending the piston rod and using a second piston that slides in a compressing
cylinder with the required parts.
The forward motion of the piston produces in the single engine the compression
of the volume of air admitted to the cylinder and evolves thereby heat, the degree
of heat being in proportion to the density of the compressed air. This heat may be
utilised by surrounding the steam cylinders with a water jacket that is connected
with the boiler, and brings the water under boiler pressure in contact with said
heated surfaces, so as to take up the heat and prevent the overheating of the cylinder
walls.
The compressed air being forced into the boiler, sprayed through the mass of
water therein, and mingled with the steam, furnishes thereby a more powerful
expansive medium than either air or steam alone, which is then applied to drive the
engine, so as to overcome by the greater power of the steam and air mixture the
resistance of the air compressed in the cylinder. The boiler water being charged
with air boils at 192° F. at a lower temperature than water, and imparts to the
mixture of air and steam at 192° an expansive power from 8 to 9 times greater
than dry air, which exerts a greater power on the piston and gives a greater speed
to the engine with the same or even less fuel than in the customary generation of
the steam, so as to produce a considerable saving of the same.
In the double-acting engine and compressor, air is compressed at the forward and
return motion of the piston, the steam. being exhausted by the opening of the
exhaust valves and finally expelled by fresh air forced in by suitable means, so as
to furnish atmospheric air under light pressure in time for the compressing action of
the piston. The supply of steam and the compression of air take place instantaneously
at opposite sides of the piston, and cause thereby the evolving of a greater amount
of heat by the compression of air by both the forward and return motion of the
cylinder, and, in connection therewith, a proportionate supply of the expansive
steam and air mixture.
If desired, a part of the compressed air may be collected in a suitable compressor,
and employed as a supplementary motive power for the driving of smaller
machinery of various kinds.