IM- PROVEMENTS IN HEATED AIR ENGINES
Year: 1867

page_text: LETTERS PATENT to Francis Herbert Wenham, of 1, Union Road,
Clapham, in the County of Surrey, Engineer, for the Invention of "IM-
PROVEMENTS IN HEATED AIR ENGINES."
Sealed the 13th August 1867, and dated the 18th March 1867.
PROVISIONAL SPECIFICATION left by the said Francis Herbert Wenham
at the Office of the Commissioners of Patents, with his Petition, on the
18th March 1867.
I, FRANCIS HERBERT WENHAM, of 1, Union Road, Clapham, in the County
of Surrey, Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN HEATED AIR ENGINES," to be as follows:-
The first part of my Invention relates to a means whereby the upper
portion of the working cylinder is made to serve the purpose of the separate
air pump usual in caloric engines; the top of the cylinder is closed by a
lid. The piston is provided with a hollow extension known as a "trunk" in
steam engines; this trunk may conveniently be about half the diameter of the
piston, with which it forms one casting. The trunk passes through the cover
of the cylinder, and is made air-tight by a cup leather. At the top of the
cylinder there is a passage containing two valves, one opening from the
atmosphere and the other towards the channel communicating with the
furnace. By the reciprocations of the piston this arrangement acts like an
ordinary blowing cylinder, and forces air into the furnace. The under part of
the piston is prolonged downwards to prevent hot air from coming into contact

page_text: with the working portion of the cylinder. To the bottom of the piston is
jointed the connecting rod; this vibrates through the trunk and works direct
on to the crank of the main shaft, which revolves in bearings or standards
bolted on to the upper flange of the cylinder.
my
The second part of Invention consists of a heater or stove for expanding
the air for working the engine. The stove has a partition near the grate,
above this is a feeding tube or hopper bolted to the lid of the stove, where it
is closed air-tight by a metal stopper. There is a similar stopper beneath the
grate for the removal of asbes; the hopper descends to within three inches of
the grate, and should contain enough fuel for several hours' work. The fuel
descends as it is burned, and all products of combustion having to pass through
previously ignited fuel, smoke is thus consumed. The air passage leading
from the top of the cylinder enters beneath the grate. There is an inner
loose ring within the stove forming an annular space; this protects the outside
of the stove from being overheated, and further to prevent which cold air may
be conveyed into the space by a channel leading from the air passage. Every
stroke of the piston discharges the air from its upper side to below the furnace.
The expanded air is conveyed by a pipe near the top of the stove to the valve
chest, where it is admitted beneath the piston, which is forced upwards by the
pressure. The valves are of the "poppet" kind; both the inlet and exhaust
are worked direct from the crank shaft by cams, the looped upper ends of
the valve rods embrace the shaft, and are provided with rollers running on
the cams.
The third part of my Invention is for an improved governor applicable to
these and other engines. The socket that slides on the vertical spindle is
grooved quite across at its upper end; there are pins through each extremity
of the groove, upon which the balls swing. The arms are turned over inwards
like a bent lever, and their round ends bear upon a tablet fitting into the
groove forming part of the vertical spindle, by the rotation of which the balls
fly out, and by the leverage of their beat ends raise up the sliding socket in
addition to their own weight. The sliding socket is connected with the
throttle or regulating valve in the usual way. In air engines the speed may
be regulated by letting air escape in and out by connecting the governor with
a valve set in the air pump passage or lid, or more or less cold air may be
sent into the annular space round the stove by a throttle valve worked by the
governor.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Francis Herbert Wenham, in the Great Seal Patent
Office on the 16th September 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANCIS
HERBERT WENHAM, of 1, Union Road, Clapham, in the County of Surrey,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of March, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirtieth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Francis Herbert Wenham, Her special licence that I, the said Francis Herbert
Wenham, my executors, administrators, and assigns, or such others as I, the
said Francis Herbert Wenham, 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 HEATED AIR ENGINES," upon the condition (amongst
others) that I, the said. Francis Herbert Wenham, my executors or
administrators, 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 Francis Herbert Wenham, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement:
In the following statement and accompanying Drawings the same letters
of reference indicate corresponding parts throughout the Figures.
The first part of my Invention relates to a means whereby the upper portion
of the working cylinder is made to serve the purpose of the separate air pump
usual in caloric engines. The top of the cylinder a, a, Figs. 1, 2, and 3, is
closed by a lid; the piston 6 is provided with a hollow extension c known as a
"trunk" in steam engines; this trunk may conveniently be about half the
diameter of the piston with which it forms one casting; the trunk passes
through the cover of the cylinder, and is made air-tight by a cup leather; at

page_text: the top of the cylinder there is a passage d containing two valves e, e, one
opening from the atmosphere and the other towards the channel f communi-
cating with the stove or furnace 9. By the reciprocation of the piston this
arrangement acts like an ordinary single-acting blowing cylinder, and forces
air into the furnace. The under part of the piston is prolonged downwards
to prevent hot air from coming into contact with the working portion of the
cylinder. To the bottom of the piston is jointed the connecting rod h; this
vibrates through the trunk and works direct on to the crank of the main
shaft i, which revolves in bearings or standards bolted on to the upper flange of
the cylinder.
The second part of my Invention consists of a heater or stove for expanding
the air for working the engine. The stove 9 has a partition near the grate k,
above this is a feeding tube or hopper 7 bolted to the lid of the stove, where it
is closed air-tight by a metal stopper; there is a similar stopper m beneath
the grate for the removal of ashes. The hopper descends to within three
inches of the grate, and should contain enough fuel for several hours' work.
The fuel descends by its own weight as it is burned, and all products of com-
bustion having to pass through previously ignited fuel smoke is thus consumed.
The air passage leading from the top of the cylinder enters both above and
below the grate at n, n.
The stove is lined with fire-brick, this prevents the
outside from being overheated. Every stroke of the piston discharges the air
from its upper side through the passages n, n, into the stove; the expanded
air is conveyed by a pipe o from the top of the stove to the valve chest p,
where it is admitted beneath the piston, which is forced upwards by the
pressure. The valves are of the poppet kind, both the inlet and exhaust are
worked direct from the crank shaft by cams q, q; the looped upper ends of
the valve rods embrace the shaft, and are provided with rollers running on the
cams. The arrangement is best seen in Fig. 4, which shows the valve chest
in section.
The third part of my Invention is for an improved governor applicable to
these and other engines. The socket a, a, Figs. 5, 6, and 7, that slides on
the vertical spindle 6 is grooved quite across at its upper end; there are
pins d, d, through each extremity of the groove upon which the balls swing;
the arms are turned over inwards like a bent lever at c, c, and their round
ends bear upon a tablete fitting into the groove, and forming part of the
vertical spindle, by the rotation of which the balls By out, and by leverage
from their bent arms raise up the sliding socket in addition to their own
weight. The sliding movement of the socket is conveyed to the throttle or
regulating valve in the usual way.

page_text: In air engines the speed may be regulated by letting air escape in and out
by connecting the governor with a valve set in the air pump passage or lid,
or more or less cold air may be sent into the upper or lower space in the
stove 9, Fig. 1, by a throttle valve r worked by the governor, which will open
or close either the upper or lower passage, and thus regulate the combustion
of the fuel according to the power required to work the engine.
Having thus described the nature and action of my Invention I would have
it understood that-
I claim the application of a feeding chamber or hopper reaching down to
near the grate, so that the store of fuel descends by its own gravity as it is
consumed, and the products of combustion from the raw fuel must pass
through the portion previously ignited.
I also claim the mode of regulating the speed and power of the engine by
attaching the governor to a valve that will admit more or less air above or
below the fuel, as shown.
I further claim the governor described.
In witness whereof, I, the said Francis Herbert Wenham, have hereunto
set my hand and seal, this First day of August, in the year of our
Lord One thousand eight hundred and sixty-seven.
FRANCIS HERBERT WENHAM.
(L.S.)