IMPROVEMENTS IN ROTARY ENGINES
Year: 1882

page_text: LETTERS PATENT to William Phillips Thompson of the Agency for Foreign
Patent Solicitors, 6 Lord Street Liverpool in the County of Lancaster and
323 High Holborn in the County of Middlesex, Civil Engineer, for an invention
of "IMPROVEMENTS IN ROTARY ENGINES."-A communication from abroad by
Dexter D. Hardy of Chicago in the County of Cook, in the State of Illinois,
United States of America.
PROVISIONAL SPECIFICATION left by the said William Phillips Thompson
at the Office of the Commissioners of Patents on the 9th May 1882.
33
WILLIAM PHILLIPS THOMPSON of the Agency for Foreign Patent Solicitors
6 Lord Street, Liverpool in the county of Lancaster, and 323 High Holborn in
the county of Middlesex Civil Engineer "IMPROVEMENTS IN ROTARY ENGINES
A communication from abroad by Dexter D. Hardy of Chicago in the county of
Cook in the state of Illinois United States of America.
This Engine is an improvement on an engine invented by Dexter D. Hardy and
patented by him in the United States of America, November 14th A.D. 1876,
No. 184284, and in its general features of construction is much the same.
It
This engine is designed for a rotary steam motor but may also be adapted for
use as a water motor compressed air engine, pump or blowing machine.
consists :-
First. of a stationary cylinder with the usual heads and ports in which the
steam is admitted or discharged.
Second. Inclosed between the heads of said cylinder is an annular internal
toothed cylinder of slightly less diameter than said stationary cylinder and made
to revolve within the same. On the outer rim or periphery of said inner toothed
cylinder. are three or more ribs, raised sufficiently to just fit against the inner
surface of said outer cylinder; between said ribs and the inner and outer cylinders
are inclosed spaces into which steam is admitted from the inside of the engine
through suitable holes drilled through the revolving cylinder. Said internal
cylinder is provided with two or more preferably three extra sized teeth or lugs,
placed at equal distances apart, projecting towards the centre of the cylinder which

page_text: '
form the steam abutments against which the steam acts to turn the cylinder as
hereinafter described. On the outer ends of each of said large teeth is made a
cavity into which is fitted a metallic strip or packing pressed outwardly by a
spring or by means of steam admitted into an aperture above said strip-a pin
or other suitable device is used to prevent said metallic strips from being pressed
out too far
Third. With the teeth of said internal tooth revolving cylinder is engaged a
wheel or pinion of equal thickness with that of said cylinder but of only about
two thirds of the diameter of said revolving cylinder measured in the pitch lines
and like the same extending from head to head. This pinion or wheel is provided
on its periphery with recesses to recover and let pass the large teeth of the
revolving cylinder and is set on a shaft or axle which passes through suitable
bearings and packing on one or both of the cylinder heads from whence the power
is applied to the operation of machinary.
Fourth Filling the space not swept over by the large teeth of the revolving
cylinder nor the teeth of the pinion and extending from head to head of the
cylinder, is a crescent-shaped block which confines the steam to its pressure on the
large teeth of said annular revolving cylinder after they pass the port and enter
upon the crescent. The outer or larger curve of the crescent block is concentric
with the annular toothed cylinder, the inner curve is in contact with the teeth of
the pinion and the block may be fastened to or form part of the head or heads of
the cylinder. In the concave side of said crescent and above said pinion is made
a cavity into which is fitted a piece of metal preferably rectangular in shape with
its lower surface curved to correspond with said crescent. This metallic piece is
pressed outward against the teeth of the pinion either by a spring or by means of
steam admitted into a space above the same through a suitable hole made therein
and is to serve as a packing to prevent steam from passing between the pinion
and said crescent. Passing through one of the heads near each point of the
crescent block are two steam ports which are convertible as supply or exhaust
ports.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Phillips Thompson in the Great Seal Patent Office on
the 9th November 1882.
WILLIAM PHILLIPS THOMPSON, of the Agency for Foreign Patent Solicitors,
6, Lord Street, Liverpool, in the County of Lancaster, and 323, High Holborn, in
the County of Middlesex, Civil Engineer. "IMPROVEMENTS IN ROTARY-ENGINES."-
A communication from abroad by Dexter D. Hardy of Chicago, in the County
of Cook, in the State of Illinois, United States of America.
-
In
This Engine is an improvement on an engine invented by Dexter D. Hardy and
patented by him in the United States of America November 14th A.D. 1876,
No. 184284, and in its general features of construction is much the same.
order that the invention may be fully understood I will now proceed to describe
the said improved engine as a whole and then point out the features which are
claimed as new and which constitute the present invention.
This Engine is designed for a rotary steam motor but may also be adapted for
use as a water motor compressed air engine, pump or blowing machine.
consists.
It
First. Of a stationary cylinder with the usual heads and ports in which the
steam is admitted or discharged.
Second. Enclosed between the heads of said cylinder is an annular internal
toothed cylinder of slightly less diameter than said stationary cylinder and made
to revolve within the same on the outer rim or periphery of said inner toothed
cylinder are three or more ribs, raised sufficiently to just fit against the inner
surface of said outer cylinder; between said ribs and the inner and outer cylinders
are enclosed spaces into which steam is admitted from the inside of the engine
through suitable holes drilled through the revolving cylinder. Said internal
cylinder is provided with two or more, preferably three extra sized teeth or lugs
placed at equal distances apart, projecting towards the centre of the cylinder,
which form the steam abutments against which the steam acts to turn the cylinder,
as hereinafter described. On the outer ends of each of said large teeth is made a
cavity into which is fitted a metallic strip or packing pressed outwardly by a
spring or by means of steam admitted into an aperture above said strip a più or
other suitable device is used to prevent said metallic strips from being pressed out
too far.
Third. With the teeth of said internal tooth revolving cylinder is engaged a
wheel or pinion of equal thickness with that of said cylinder but of only about
two thirds of the diameter of said revolving cylinder measured in the pitch lines
and like the same extending from head to head. This pinion or wheel is provided
on its periphery with recesses to recover and let pass the large teeth of the
revolving cylinder and is set on a shaft or axle which passes through suitable
bearings and packing on one or both of the cylinder heads from whence the power
is applied to the operation of machinery.
Fourth Fitting the space not swept over by the large teeth of the revolving
cylinder nor the teeth of the pinion and extending from head to head of the
cylinder is a crescent shaped block which confines the steam to its pressure on the
large teeth of said annular revolving cylinder after they pass the port and enter
upon the crescent.
The outer or larger curve of the crescent block is concentric with the annular
toothed cylinder the inner curve is in contact with the teeth of the pinion and the
block may be fastened to or form part of the head or heads of the cylinder,
In

page_text: the concave side of said crescent and above said pinion is made a cavity into which
is fitted a piece of metal preferably rectangular in shape with its lower surface
curved to correspond with said crescent. This metallic piece is pressed outward
against the teeth of the pinion, either by a spring or by means of steam admitted
into a space above the same through a suitable hole made therein and is to serve
as a packing to prevent steam from passing between the pinion and said crescent
Passing through one of the heads near each point of the crescent block are two
steam ports which are convertible as supply or exhaust ports.
:
Referring to the drawings Fig 1 represents a perspective view showing the
interior of the engine with the nearest cylinder head removed and Fig: 2 a sectional
elevation through the line xx.
In these A, is the stationary cylinder B B', are the cylinder heads C, is the
annular internal toothed cylinder b b b the large teeth or steam abutments, ccc
metallic strips or packing fitted into cavities in the end of said large teeth dd d
are the ribs on the rim or periphery of said revolving cylinder which may be formed
by metallic strips fitted into suitable cavities cut out of the rim of said cylinder,
or by making said revolving cylinder of a diameter to exactly fit into said outside
cylinder and carving out the spaces between said ribs e e e, are steam spaces
between said ribs and said inner and outer cylinders, f is a hole drilled through
said revolving cylinder to admit steam from the inside of the engine into the
spaces e e e; D is the pinion g g spaces cut out of said, 'pinion to admit the large
teeth or lugs of the revolving toothed cylinder; E is the crescent shaped block
between the cylinder heads and the pinion and revolving cylinder, is the metallic
block or packing fitted into a cavity in said crescent block and pressed outward
against said pinion teeth by means of steam admitted above said block or by a
spring. i,, indicate the location of the steam ports through the cylinder heads
which are also further shown by the arrow-heads: j is a steam pipe through
which the steam passes from the boiler into the steain port i.
The operation of this engine is as follows: steam from the steam boiler enters
by the steam pipe j through the open port i, indicated by the arrow head near
where the wheels become disengaged into the space between the one side of the
pinion D, cylinder C, heads B B and the large tooth or lug b, the other side of the
pinion D being open to exhaust through the port i'.
The contact of the teeth of the pinion D with the inner curve of the crescent
block E and the metallic packing prevents the steam from passing to the other
h
port and it therefore acts on the tooth b which is seated on the crescent E and
carries it around over the crescent towards the exhaust port thus rotating the
cylinder C, the teeth of said cylinder C, engaging the teeth of the pinion D also
canse it to rotate in the same direction but at a higher rate of speed. the steam is
prevented from passing between the large teeth b, b, b, and the crescent E by the
metallic packing c, pressing against said crescent. The force of the steam on the
tooth b will continue to be exerted until the succeeding large tooth enters and
becomes seated on the crescent, when said latter tooth is in turn acted upon, and
the steam between said teeth is balanced and at ouce ceases to have any effect on
the action of the engine and as soon as said advance tooth ceases, contact with the
crescent exhausts through the exhaust port . The cylinder C, will therefore be
kept revolving in the same direction by the pressure acting successively upon each
tooth b, as it comes up into position. By shifting a valve so as to admit the steam
through the exhaust port and opening the other port as an exhaust port the
cylinder C is made to revolve in the opposite direction.
When the steam is let into the engine it passes through the several holes f into
the spaces between the ribs. d d d, revolving cylinder C and the stationary cylinder
or shell A, and thus counterbalances the pressure of the steam against said revolving
cylinder from the inside and prevents the friction that would otherwise result from
the steam pressing said cylinder C against said shell.
This side or downward pressure has been one of the great defects in nearly all
rotary engines and was a very serious defect in the engine invented and patented

page_text: by Dexter D. Hardy in the United States of America as aforesaid of which this is
an improvement. By admitting steam into said enclosed spaces between said
cylinders this defect may be overcome.
Another defect in the original engine of which this is an improvement was the
great difficulty in preventing the steam from passing underneath the crescent
block C, between it and the teeth of the pinion. By means of the metallic packing h
pressed outward against the teeth of said pinion by steam admitted above said
packing this defect may be overcome.
The foregoing description is for a single engine exhausting at about the same
pressure at which it receives the steam. In order to exhaust under a greatly reduced
pressure from that at which it receives the steam, two or more engines in combi-
nation are used constructed in the same way, except that an additional port is
provided over the crescent C, from which the steam is conveyed by a suitable pipe
to the second engine, entering said second engine in the same manner and at the
same relative place that it enters the first engine.
By this arrangement the steam may be exhausted at or near the atmospheric
pressure. It will be observed that substantially all of the steam that enters this
engine passes through the space between the cylinder A and the crescent C, and
that as soon as the two large teeth upon which the steam acts to drive the cylinder A,
have entered and become seated upon the crescent C, the steam enclosed within the
space between said two teeth becomes inoperative to move the engine in either
direction as it is balanced and presses in each direction alike and consequently
ceases to have any effect upon the working of the engine whether the pressure be
little or great. By successively opening a port by suitable mechanism as often as
the engine is in this position and allowing the steam to pass from this space into
the secondary engine said secondary engine being several volumes greater in
capacity than the first, the steam thereby acts a second time on a piston of greater
area, and greatly increases the power of the engine. In most other forms of con-
struction of compound engines there is a great loss of power in consequence of the
back pressure of the steam on the moving piston of the first engine. As the steam
in this engine at the time the port is opened to admit it into the secondary engine
is balanced as above stated there is no such back pressure.
Having now described the invention as communicated to me I wish it to be
understood that what I desire to protect under the hereinbefore in part Recited
Letters Patent is :-
1st A rotary engine having an internally toothed cylinder C, made to revolve
within a stationary outside shell with recesses between said eylinder and outside
shell to receive steam through suitable passage from the inside of said cylinder, and
for the purpose of counterbalancing the steam pressure on the inside of said cylinder
and preventing the friction which would otherwise result from the steam pressing
said cylinder against said outside shell, constructed substantially as herein described
and for the uses and purposes specified.
2nd In a rotary Engine herein described the combination of the internally toothed
cylinder C, having lugs b, b, b, and ribs d, d, d, with the crescent E, and shaft H,
substantially as aud for the purpose specified.
3rd In a rotary Engine the combination with the shell A. having heads B B¹. of
the internally toothed cylinder C. having ribs d, d, d, holes f, and lugs b, b, b, with
strips of metal at their extremities pressed outwardly by springs or steam, the
crescent E having metallic packing / pressed outwardly by steam or by a spring
and the pinion D. having recesses g, g, and shaft H substantially as and for the
purpose specified.
4th In a rotary Engine herein described the crescent block E having the metallic
packing h provided with a hole to admit steam to a recess above said packing for
the purpose specified.
5th In a rotary engine herein described the annular internal toothed cylinder C,
having ribs d, d, d, holes f and lugs b, b, b, with strips of metal at their extremities
pressed outwardly by springs for the purpose specified.

page_text: 6th The internally toothed cylinder C, having lugs b, b, b, and ribs d, d, d, the
crescent E, having metallic packing h the pinion D, having recesses g, g, and shaft H,
in combination with the shell A, head B, and head B', having ports i, i, substantially
as and for the purposes herein set forth.
In witness whereof I the said William Phillips Thompson have hereunto set
my hand and seal this seventh day of November in the year of our Lord
one thousand eight hundred and eighty two.
W. P. THOMPSON. (L.S.)