IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR OBTAINING AND APPLYING MOTIVE POWER
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by William Patrick Kelly at the Office
of the Commissioners of Patents on the 25th November 1880.
WILLIAM PATRICK KELLY, of Mount Brandon, near Graigue, in the County of
Carlow, Ireland, Lieutenant in the Reserve of Officers. "IMPROVEMENTS IN THE
METHOD OF AND APPARATUS FOR OBTAINING AND APPLYING MOTIVE POWER."
My Invention relates to a method of using the alternate vaporization and
condensation of the vapour of ether, gasoline, or of other suitable volatile liquids
for the production and application of motive power by means of a suitable
construction of apparatus, such as is hereinafter described, in a safe, simple, and
economical manner.
In the apparatus used in this Invention the use of a separate boiler is dispensed
with, and the cylinder of the apparatus or engine acts both as boiler and condenser.
The cylinder is made considerably longer than is ordinarily required in engines
having the same length of stroke, so as to leave at each end of the cylinder a space
over which the piston does not travel; the size of these spaces will depend,
interalia, on the pressure at which it is intended to work the engine; thus, assuming
the pressure in the cylinder to be about twenty pounds per square inch, each of
these spaces will be equal in volume to about half the volume of that portion of
the cylinder over which the piston travels. The outside of the cylinder is enveloped
by three jackets, videlicet, one at each end and one in the middle, for holding
water at different temperatures, the end jackets containing water as hot as may
be desired, and the middle jacket water as cold as can be conveniently obtained.
The end jackets extend along the cylinder to a short distance, depending on the
amount of compression that it may be thought desirable to use beyond the point
to which the piston reaches at each end of the stroke, and the centre jacket extends
along the cylinder between the other two jackets with only a short interval
between. The hot and cold water is made to circulate through these jackets by
feed pumps. The hot water may be heated by being passed through a coil of iron
piping heated by a fire of coal, wood, or gas. In other respects the engine is of the
construction of an ordinary steam engine consisting merely of a cylinder and piston
with the usual piston rod and fly wheels, no slide valves being required. The

page_text: piston is provided with thick tight-fitting discs or brushes of suitable material,
such as vulcanized india rubber, one at each side; the use of which is to brush
back to the end of the cylinder the drops of liquid which may condense on the
sides of the cylinder during the working of the engine.
The operation is as follows:
The cylinder being filled with vapour of (say for example) ether, the fly wheel
is turned till the piston reaches the end of the stroke, and the wheel is retained in
that position. Hot water being then allowed to flow into the end jackets, the
vapour in the end of the cylinder next the piston rapidly rises in temperature and
pressure, the pressure at the other end being that corresponding to the temperature
of the cold water according to the principle known as "Watt's law." When the
desired working pressure is obtained the wheel is released and the pressure in the
cylinder drives forward the piston, there being only a comparatively small back
pressure against it. As the piston moves forward the space containing the vapour
is increased; the latter expands till its pressure becoming less, nearly equals the
back pressure; it then, by contact with the cold sides of the middle of the cylinder
condenses in drops on the latter, and its pressure falls to that corresponding to the
temperature of the cold water. Meanwhile the piston, being carried forward by
the fly wheel, moves on to the hot water jacketted portion of the other end of the
cylinder, the brushes on the piston brushing before them the drops of liquid which
may have condensed on the cold part of the sides of the cylinder. As soon as
these drops of liquid enter the hot part of the cylinder, and the vapour is confined
to the hot-water-jacketted space, the pressure of the vapour rises at once to the
pressure which corresponds to the temperature of the hot water, and the piston
being carried past the dead point by the action of the fly wheel begins the return
stroke under the action of this pressure, the back pressure being, as before, that
corresponding to the temperature of the cold water. This, action goes on as long
as the engine is working, the effective working pressure on the piston at the
beginning of the stroke being equal to the difference between the pressures
corresponding to the temperatures of the hot and cold water respectively, and the
pressure may be expanded down to a pressure nearly equal to the back pressure.
When the herein before described apparatus or engine is used for other purposes
than for pumping water, a suitable governor must be applied to it. The following
governor is one which would be suitable:-
An ordinary governor of any known construction is connected with a pair of
excentrics and a link, so arranged that when the speed of the engine increases one
of the excentrics will be thrown into action and will allow some of the vapour to
pass out of each end of the cylinder alternately when the pressure is highest into a
suitable receiver, and when the speed of the engine falls the other excentric coming
into action will allow some vapour from the said receiver to pass into the cylinder
at each end alternately when the pressure is lowest; the vessel or receiver into or
out of which the vapour passes is kept at a temperature intermediate between the
temperatures of the hot and cold water, the pressure of the vapour in this vessel
will therefore be greater than the lowest pressure, and less than the greatest
pressure in the cylinder.