IMPROVEMENTS IN AIR ENGINES
Year: 1880

page_text: LETTERS PATENT to Louis Sterne, of Victoria Chambers, in the City of
Westminster, Engineer, for an Invention of "IMPROVEMENTS IN AIR ENGINES."
A communication from abroad by John Ericsson, of New York, in the United
States of America. ·
PROVISIONAL SPECIFICATION left by the said Louis Sterne at the Office
of the Commissioners of Patents on the 27th July 1880.
LOUIS STERNE, of Victoria Chambers, in the City of Westminster, Engineer.
"IMPROVEMENTS IN AIR ENGINES." [A communication from abroad by John
Ericsson, of New York, in the United States of America.]
This Invention relates to that class of air engines in which, by the action of the
piston, which may be termed the "exchange-piston," working in a cylinder at or
near one end of which is the working piston, and at the other end of which is the
fire place, the same air is over and over again transferred from each end of the said
cylinder to the other alternately, being heated and expanded during its transference
in one direction, and being cooled and contracted during its transference in the
other direction, the said piston also performing the office of a regenerator.
One part of the Invention consists in a novel system of mechanism for trans-
mitting motion from the working piston to a crank and to the exchange piston,
whereby, with a short stroke of the working piston, I obtain both a long crank and
a long movement of the exchange piston, and the movements of the two pistons
relatively to each other are so timed as to obtain the most effective action.
Another part of the Invention consists in a novel arrangement of a pump and its
connections with an air engine, whereby I obtain a very effective pumping engine
with a short stroke of the engine piston, and a very long proportionate stroke of
the pump plunger or piston.
The improvements may be carried out as follows:-
The cylinder of the engine is open at the upper end, and contains two pistons,
viz., the working piston and the exchange piston. The lower part of the cylinder
is closed, and intended to be heated by gas, coal, or other fuel, with a burner or

page_text: fire place of any suitable construction. The working piston, which is in the upper
part of this cylinder, is packed in any suitable manner to work air tight therein.
The exchange piston, which is of considerable length in an axial direction, is so
much smaller than the cylinder that an annular space for free passage of air is left
between its exterior and the interior of the cylinder. The said cylinder is preferred
to be hollow, and to have its upper part which is farthest from the fire or heat
partly filled with cotton or other fibrous material, below which, enclosed, is a
stratum of powdered charcoal or other such non-conducting material as will protect
the fibrous material from taking fire by the heat to which the bottom part of the
piston is subjected.
The working piston is connected by a hollow rod or trunk and short side links
with a beam above the cylinder, the connection being at a short distance from the
fixed centre of oscillation of the beam. This beam is connected at a much greater
distance from the other side of the said centre by a connecting rod with a crank on
the main shaft of the engine, which is arranged on one side of the cylinder. This
crank is also connected by a rod with one arm of a bell crank lever which has a
fixed centre of oscillation, and the other arm is forked and connected by arched
side rods on opposite sides of the cylinder with the head of the piston rod of the
exchange piston. This piston rod passes through the hollow rod or trunk of the
working piston, and is packed air tight by a stuffing box in the top of the said
hollow rod or trunk.
The centre of oscillation of the bell crank is arranged on the same side of the
cylinder as the crank shaft, but nearer to the side of the cylinder and farther from
the upper part in which the working piston works.
By means of this system of connections the beam receiving motion from the
working piston is caused to transmit motion through the mechanism above described
to the exchange piston.
The movements of the pistons are as follows:-During the upward movement of
the exchange piston the cool air from the upper part of the cylinder will be
transferred by the said piston through the annular space between it and the
cylinder to the bottom and lower part of the latter, which is heated as above
described. The air so transferred becoming heated expands in the lower part of
the cylinder, and its expansion causes it to force the working piston upward. This
movement of the exchange piston is about three fourths completed before the
working piston commences its upward movement by which its work is done, and
when the working piston has nearly completed the upward or working stroke, the
exchange piston begins to descend and force the hot air back from the lower heated
to the upper cool part of the cylinder, completing its stroke by the time the working
piston has made about one third of its return stroke.
It will be understood that with such a movement of the piston as above
described, the working piston is actuated by the air which is confined in the
cylinder; and which is caused to be heated and cooled alternately by the peculiar
motion of the exchange piston, which transfers it from the heated to the cool, and
from the cool to the heated part of the cylinder.
It will be evident that the large surface presented by the outside of the long
exchange. piston, and inside of the long cylinder, will cause a rapid change of
temperature of the latter, the exchange piston thus performing the office of what.
has been termed in air engines a "regenerator."
By the arrangement of the crank shaft, the centres of motion of the beam and
bell crank lever, and of the connections, I obtain a long crank with a short stroke
of the working piston, and obtain a long stroke of the exchange piston with such
long side rods or yoke for working the latter piston, and such slight deviation from
a right line in the movement of the said side rods or yoke that guides for tho said
rods or yoke are unnecessary.
The pump before referred to is arranged on the opposite side of the cylinder to
the crank shaft: The piston or plunger rod of this pump is connected with the.

page_text: beam on the same side of the centre of oscillation of the latter as the engine piston
connections, the beam being prolonged beyond the cylinder for the purpose of
making this connection, and so obtaining the well understood advantage of a long
stroke for the pump with a short stroke of the working piston of the engine. This
pump may deliver its water through a jacket which surrounds the upper part of
the engine cylinder, for the purpose of cooling that part of the said cylinder, and so
effecting a more rapid cooling of the air on its transference from the lower to the
upper part of the said cylinder. This jacket however is not necessary to the
successful cooling of the air in the cylinder; itself being very long, it presents a large
radiating surface which may be further increased by corrugating the external
surface of its upper part.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Louis Sterne in the Great Seal Patent Office on the 26th January
1881.
LOUIS STERNE, of Victoria Chambers, in the City of Westminster, Engineer.
"IMPROVEMENTS IN AIR ENGINES." A communication from abroad by John
Ericsson, of New York, in the United States of America.
This Invention relates to that class of air engines in which, by the action of a
piston, which may be termed the "exchange piston," working in a cylinder at or
near one end of which is the working piston, and at the other end of which is the
fire place, the same air is over and over again transferred from each end of the said
cylinder to the other alternately, being heated and expanded during its transference
in one direction, and being cooled, and contracted during its transference in the
other direction, the said piston also performing the office of a regenerator.
One part of the Invention consists in a novel system of mechanism for transmitting
motion from the working piston to a crank and to the exchange piston, whereby,
with a short stroke of the working piston I obtain both a long crank and a long
movement of the exchange piston, and the movements of the two pistons relatively
to each other are so timed as to obtain the most effective action.
Another part of the Invention consists in a novel arrangement of a pump and its
connections with an air engine, whereby I obtain a very effective pumping engine
with a short stroke of the engine piston, and a very long proportionate stroke of
the pump plunger or piston.
Another feature of the Invention relates only to air engines for pumping water,
and has for its object the effective and economical cooling of that part of the air
cylinder in which the air is required to be cooled. In order to obtain this result, I
surround that part of the cylinder with a water jacket; and this part of my
Invention consists in so combining such jacket with the water pump of such an

page_text: engine that the water passing through such pump is caused to circulate by a forced
pressure through the said jacket. The water thus circulating round the cylinder
cools it very effectively, and without imposing any appreciable additional work
upon the engine beyond that of its regular duty of pumping.
In the accompanying Drawings, Figure 1 is a vertical section of an upright
engine constructed according to this Invention, especially adapted for pumping, but
also capable of use for other purposes; Figure 2 is an elevation of the same;
Figure 3 is a central vertical section of a gas furnace for heating the lower part of
the cylinder; Figure 4 is a horizontal section in the line x, x, Figure 3.
S is the cylinder of the engine open at the upper end, and containing two pistons,
viz., the working piston A and the exchange piston B. The lower part of the said
cylinder is closed and intended to be heated by gas, coal, or other fuel, with a
burner or fire place of any suitable construction. The working piston A, which is
in the upper part of this cylinder, is packed in any suitable manner to work air
tight therein.
The exchange piston B, which is of considerable length in an axial direction, is
so much smaller than the cylinder that an annular space for free passage of air
is left between its exterior and the interior of the cylinder. The said piston is
represented as hollow, and having its upper part, which is farthest from the fire or
heat, partly filled with cotton or other fibrous material a, a, below which enclosed
is a stratum b of powdered charcoal or other such non-conducting material as will
protect the fibrous material from taking fire by the heat to which the bottom part
of the piston is subjected.
The working piston A. is connected by a hollow rod or trunk A', and short side
links A, with a beam C above the cylinder, the connection being at a short distance
from the fixed centre of oscillation c of the beam. This beam is connected at a
much greater distance from the other side of the said centre c by a connecting
rod D with the crank E on the main shaft E' of the engine, which is arranged on
one side of the cylinder. This crank is also connected by a rod F with one arm G
of a bell crank lever G, G¹, which has a fixed centre of oscillation at g, and the
other forked arm G¹ is connected by side rods H on opposite sides of the cylinder
by a yoke with the head.
The piston rod B₁ of the exchange piston B passes through the hollow rod or
trunk A' of the working piston, and is packed air tight by a stuffing box B² in the
top of the said hollow rod or trunk. The centre of oscillation of the bell crank is
arranged on the same side of the cylinder as the crank shaft, but nearer to the
side of the cylinder and farther from the upper part in which the working piston
works.
By means of this system of connections the beam receiving motion from the
working piston is caused to transmit motion through the rod D to the crank E,
which is caused to transmit motion through the rod F, the bell crank lever G, G¹,
and the rods or yoke H to the exchange piston.
"
The movement of the pistons are as follows:-During the upward movement of
the exchange piston the cool air from the upper part of the cylinder will be
transferred by the said piston through the annular space between it and the
cylinder to the bottom and lower part of the latter, which is heated as above
described. The air so transferred becoming heated expands in the lower part of
the cylinder, and its expansion causes it to force the working piston upward. This
movement of the exchange piston is about three fourths completed before the
working piston commences its upward movement by which its work is done; and
when the working piston has nearly completed the upward or working stroke, the
exchange piston begins to descend and force the hot air back from the lower heated
to the upper cool part of the cylinder, completing its stroke by the time the working
piston has made about one third of its return stroke.
It will be understood that with such a movement of the piston, as above
described, the working piston is actuated by the air which is confined in the
cylinder, and which is caused to be beated and cooled alternately by the peculiar

page_text: motion of the exchange piston, which transfers it from the heated to the cool and;
from the cool to the heated part of the cylinder.
It will be evident that the large surface presented by the outside of the long.
exchange piston and inside of the long cylinder will cause a rapid change of
temperature of the latter, the exchange piston thus performing the office of what,
has been termed in air engines a "regenerator."
By the arrangement of the crank shaft, the centres of motion of the beam and
bell crank lever, and of the connections, I obtain a long crank with a short stroke
of the working piston, and obtain a long stroke of the exchange piston with such.
long side rods or yoke for working the latter piston, and such slight deviation from
a right line in the movement of the said side rods or yoke that guides for the said.
rods or yoke are unnecessary.
I is a pump arranged on the opposite side of the cylinder S to the crank shaft..
The piston or plunger rod J of this pump is connected with the beam C on the,
same side of the centre of oscillation of the latter as the engine piston con-
nections, the beam being prolonged beyond the cylinder S for the purpose of making,
this connection, and so obtaining the well understood advantage of a long stroke
for the pump with a short stroke of the working piston of the engine. This pump
is represented as delivering its water through a jacket Ķ which surrounds the
upper part of the engine cylinder, the water from the discharge port of the pump
entering the said jacket near the bottom at v, Figure 1, and passing out from said
jacket near the top thereof on the side opposite to v. The water circulates in the
jacket around the upper part of the cylinder for the purpose of cooling it, and so
causing the air on its being transferred to that part of the cylinder to be cooled
not only more rapidly but to a lower temperature than would be practicable
without the water jacket.
As the power of the engine depends on the difference between the respective
temperatures of the lower and upper parts of the air cylinder, it is obvious that its
power must be increased by the cooling effect of the circulation through the water
jacket of all the water pumped by the engine. As this cooling of the cylinder is
effected in an engine for pumping purposes without imposing any work on the
engine beyond that of its ordinary duty of pumping water, and the very slight
friction of the water in the jacket, which is scarcely appreciable, the economy of
this combination of the water jacket and pump with the cylinder is obvious.
The water jacket is not however absolutely necessary to the successful operation
of the engine, for the cylinder when made very long, as in the example represented,
presents a large exterior radiating surface, which may be further increased by
corrugating its upper part.
The gas furnace, represented in Figures 3 and 4, for heating the lower part of
the cylinder S is constructed as follows:-K, L, are outside and inside cylinders
of iron surrounding the cylinder S, having between them a filling of fire clay or
other non-conducting material, and mado with a double head P at the bottom
carrying a gas chamber M with Bunsen burners N, N, which may be removed for
cleaning. The outer cylinder K is provided with lugs h, h, through which it is
bolted to the upper bed-plate of the engine.
The Bunsen burners are represented as each composed of a set of three tubes i, i,
which may be either let through separate holes in the head P, somewhat larger
than the said tubes to admit a proper supply of air to the burners; or the holes in
the head may be, as shown in the Drawing, large enough to take in the three tubes,
the lower parts of which are surrounded by a light sheet iron tube j which rests
on the triangular base k of the burner, leaving spaces , L, between the said base
and the bottom of the said tube j for the entrance of air through the latter, and to
the holes n, n, in the lower parts of the burner tubes i, i.
I do not claim broadly a water jacket surrounding the cylinder of an air engine;
but what I claim as this Invention is,―
First. The combination with the eylinder, crank shaft, and crank of an air
engine, of a working piston and an exchange piston in the said cylinder, a beam

page_text: and connecting rod connecting the working piston with the crank, and a bell crank
lever and connections connecting the crank with the exchange piston, substantially
as herein described.
Second. The combination of the working piston A, B, beam C, connecting rod D,
crank E, connecting rod F, bell crank lever G, and rods or yoke H, all substantially
as herein described.
Third. The combination with the working cylinder and piston of an air engine
and a beam with which the said piston is connected, of a pump having its piston
or plunger connected with the said beam at a greater distance from the centre of
oscillation thereof than the connection of the working piston, substantially as and
for the purpose herein described.
Fourth. The combination with the air cylinder and the water pump of an air
engine for pumping water, of a water jacket surrounding the said cylinder, and so
connected with the said pump that the water passing through the said pump passes
also with a forced circulation through the said jacket, substantially as herein
described for the purpose set forth.
In witness whereof, I, the said Louis Sterne, have hereunto set my hand
and seal, this Twenty ninth day of December, One thousand eight hundred
and eighty