IMPROVEMENTS IN ROTATORY ENGINES
Year: 1873

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields,
in the County of Middlesex, Gentleman, for the Invention of
"IMPROVEMENTS IN ROTATORY ENGINES." A communication from
abroad by Jean Edmond Henry, of Paris, in the Republic of
France, Engineer.
-
Sealed the 7th November 1873, and dated the 10th September 1873.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 10th September 1873.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN ROTATORY ENGINES," a communication to
'me from abroad by Jean Edmond Henry, of Paris, in the Republic of
France, Engineer, to be as follows:-
This Invention relates to rotatory engines to be driven by air, water,
O gas, steam, or other fluid; and consists of a peculiar arrangement and
combination of the parts, whereby greater simplicity, speed, and com-

page_text: pactness are obtained, and injurious spaces, occasioning a large
consumption of the motive fluid, are obviated, whilst at the same time
the expansion of the fluid, which may be carried to the desired degree, is
effected without the aid of any special apparatus for that purpose.
This engine, which is designated an "axle engine," is composed of a
hollow cylinder containing a piston, which is mounted on a shaft or
axle, such shaft or axle having its bearings in the cylinder covers, and
carrying a driving pulley for the transmission of the power. The
internal transverse section of the cylinder is a figure composed of a
number of curves forming a continuous profile, which starting from a
point at which the periphery of the piston is in contact with it, and
pursuing a somewhat elliptical course, terminates by intersecting itself
at its starting point, so as to form a space between the piston and
cylinder, which constantly increases and finally again diminishes when
near their point of contact.
The piston is of a cylindrical form in cross section, and is provided
with any suitable number of flaps or vanes, which are hinged thereto,
and fitted so as to lodge in recesses formed therein for their reception,
and lie flush with the periphery of the piston, but are so curved as to be
capable of opening out or protruding (by turning on their hinge) to fit
the interior of the cylinder and form a surface on which the motive fluid
may act, the opening or protrusion of such flaps or vanes being effected
either by the intervention of springs, cams, or other suitable means, or
by admitting the fluid from its source into an annular groove commu-
nicating with spaces formed.behind the flaps.
The rubbing parts of the flaps or vanes may in some cases be provided
with friction rollers extending the length of the piston.
The piston at one portion of its periphery is in contact with the
cylinder, as before stated, and a loose piece pressed up by springs is
employed for the purpose of preventing, in case of wear, any commu-
nication between the two portions of the cylinder situate respectively at
the right and left hand side of the contact point of the piston therewith.
The cylinder is formed of such a size and shape in transverse section in
relation to the piston that the spaces between any two adjacent flaps or
vanes of the series is greater than that between the two preceding
adjacent flaps or vanes, with the exception of the last, which is less than
that comprised between the two flaps or vanes which precede it.

page_text: The engine operates in the following manner :-The fluid (which may
be gas or steam, for example) enters the cylinder through the inlet
aperture at one side of the contact point at a pressure slightly greater
than that of the medium (which in most cases would be atmospheric
air), communicating with the outlet or exhaust at the other side (a con-
denser or pump effecting a partial vacuum), and meets the first flap or
vane, upon which it acts, and causes both the piston and the shaft or
axle to rotate. A certain volume of the fluid enters the cylinder until
another flap or vane arrives at the inlet aperture to take the place of
the former, and again a third flap or vane, and so on in succession; and
as the spaces between any two adjacent flaps or vanes constantly
increases in proportion to the rotation of the piston by reason of the
shape of the cylinder, the fluid gradually and progressively expands, so
as to constantly occupy the whole of the space presented to it. The
outlet or exhaust is disposed at the most suitable point to obtain the
greatest expansion of the fluid, so that the fluid first acts at full pressure,
then expansively, and finally escapes by the outlet or exhaust.
In constructing a new engine on this system any desired degree of
expansion may be obtained by modifying the positions of the inlet and
outlet apertures, varying the number of flaps or vanes employed, and the
curvature of the internal surface of the cylinder.
When steam is the fluid used a steam jacket may be employed, and
the engine may be constituted a condensing engine by causing the steam
outlet or exhaust to communicate with a condenser.
When once an engine has been constructed however, if it is desired to
vary the degree of expansion, special apparatus will be required, cither
for the purpose of interrupting the admission of the motive fluid into the
space between two consecutive flaps or vanes before such space is filled
with fluid at full pressure (which would simply reduce the mean pressure
of the fluid without strictly acting expansively), or for changing the
position of the inlet and outlet apertures in relation to that portion of
the cylinder which is in contact with the piston.
The engine may be utilized either as a motive or retarding engine, as

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 10th March 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of September, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said John Henry Johnson, Her special license
that I, the said John Henry Johnson, my executors, administrators,
and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or 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 ROTATORY ENGINES," a communication to me from abroad by Jean
Edmond Henry, of Paris, in the Republic of France, Engineer, upon the
condition (amongst others) that I, the said John Henry Johnson, my
executors or administrators, by an instrument in writing, under my
hand and seal, 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 John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Drawings and to the letters and figures marked thereon, that is to
say:-
:―
The said Invention relates to rotatory engines to be driven by air,
water, gas, steam, or other fluid; and consists of a peculiar arrangement
and combination of the parts, whereby greater simplicity, speed, and

page_text: compactness are obtained, and injurious spaces, occasioning a large con-
sumption of the motive fluid, are obviated, whilst at the same time the
expansion of the fluid (when elastic fluids are employed) is effected
without the aid of any special apparatus for that purpose.
And in order that the said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that
purpose shall refer to the several Figures on the annexed Sheet of
Drawings, the same letters of reference indicating corresponding parts
in both Figures.
Figure 1 of the accompanying Drawings is a transverse section, and
Figure 2 a half longitudinal section and half side elevation of a rotatory
engine constructed according to this Invention.
This engine (which is designated an "axle engine") consists of a
hollow cylinder A, the internal section of which is a figure composed of
several curved lines forming a continuous profile, as shewn in the
Drawing. This cylinder is closed at its extremities by two covers B, B,
bolted thereto, which covers also serve as bearings for the rotatory shaft
or axle C, which enters the cylinder and transmits at the exterior the
mechanical power produced therein.
To the shaft or axle C there is secured a species of piston D, provided
with a number of flaps or vanes, which are hinged or jointed to the
piston or to end plates attached thereto, so as to be capable of opening
out or protruding therefrom. I have shewn in my Drawings five of such
flaps or vanes W₁, W₂, WS, W₁, W, the curves a, b, c, of which are so
arranged that a is an arc of a circle corresponding to the circumference
of the piston, and b and c are arcs of circles struck from a common
centre v. Notches or recesses are formed in the body of the piston of
such a shape that the curves b, c, always remain in perfect contact with
them during the rotation of the flaps or vanes around their respective
hinges or joints, and that such flaps or vanes may be capable of with-
drawing or closing entirely within the piston, as shewn in the case of
the flap or vane W,, the piston presenting a cylindrical form if the whole
of the flaps or vanes are closed.
The shaft or axle C is so supported in the cylinder A as to place the
external surface of the piston D in contact with the curved portion m, m³,
of the cylinder. A movable block F, acted upon by springs G, is also

page_text: provided for the purpose of pressing upon the external surface of the
piston, and takes the place of a portion of the curve m, m³, of the
cylinder, so as to prevent, in the case of wear, any communication
between the right and left hand portions of the cylinders immediately
contiguous to the curved portion m, m¹. The curve m², n, p, q, diverges
or branches out from the exterior of the piston throughout an angular
portion of, say, about 230° of its circumference, and then meets the
portion q, m, so as to join in the curve m, m', herein-before referred to.
It is obvious that by means of this arrangement the space Z comprised
between two consecutive flaps or vanes W₁, W2, for example, and also
bounded by the corresponding portion of the piston and cylinder, is
smaller than the space contained between the succeeding flaps or
vanes W2, Ws, which latter space is also smaller than that enclosed
between the following flaps or vanes W, W; on the contrary, the space
comprized between the succeeding flaps or vanes W, W, and the cor-
responding portions of the cylinder and piston is smaller than the
preceding space. Two apertures or ports H, K, are provided, commu-
nicating with the interior of the cylinder, and serving respectively for
the inlet and outlet of the motive fluid employed, whether water, steam,
or gas, as the case may be.
The apparatus operates in the following manner:-A fluid, say steam
or gas, for example, is introduced through the inlet aperture or port H.
This fluid on its entrance into the cylinder has a higher pressure than
that of the medium (in most cases atmospheric air) communicating with
the outlet or exhaust K, a condenser or pump being employed for the
purpose of effecting a partial vacuum. The fluid acts by its pressure
upon the first flap or vane which it meets, say W₂, and causes it to turn
in the direction of the arrow, and with it the piston and the shaft or
axle. A certain volume of the fluid thus enters the cylinder until a
fresh flap or vane W₁ arrives to take the place of the former, and as the
space comprised between the two flaps or vanes W₁, W2, is constantly
increasing by reason of the rotation of the piston the fluid gradually and
progressively expands, so as to constantly occupy the whole of the space
presented to it. The outlet aperture or exhaust is placed exactly at the
point suitable for obtaining the greatest amount of expansion of the
fluid, and before the commencement of the compression which would be
produced by reason of the curve q, m, of the cylinder approaching the
piston, so that it will be seen that the fluid will have operated for the
1

page_text: purpose of rotating the piston and the shaft or axle first at full pressure,
and then expansively, and that it finally escapes through the outlet or
exhaust K. This series of operations is of course repeated on the passage
of each flap or vane before the inlet and outlet apertures or ports, and the
sum of the forces tending to rotate the piston and the shaft or axle is
constantly about the same.
It is requisite in order that the apparatus may operate in a regular
and uniform manner that the flaps or vanes should have a constant ten-
dency to open out or protrude from the piston by turning on their hinge
or joint, so as to bear against the cylinder. This result may be obtained
by the aid of springs, cams, or any other suitable means.
One means employed consists in causing the spaces X₁, X₁, X3, X4, X59
produced by the rotation of the flaps or vanes to be in constant com-
munication with the source of the motive fluid; as the pressure of this
fluid is greater than that which has already operated in order to effect
the rotation of the piston, the flaps or vanes are maintained open to the
extent of which the curvature of the cylinder admits. This result is
obtained by means of the passage J, the annular groove L in the cover,
and the small orifices M₁, M., M., M., M., formed in the flaps or vanes.
It may be observed that if the curved portions b and c of the flaps or
vanes and the corresponding portions of the piston are in perfect contact,
no expenditure of the motive power is incurred by this
arrangement,
since the spaces X₁, X2, X3, X4, X5, are in communication only with the
source of the fluid..
In order to avoid the presence of water of condensation in these spaces
a mud cock may be readily applied thereto, or a continuous current of
steam may be established therein for the purpose of carrying away this
water, should any be condensed during the operation of the engine.
This engine, employed as a motive-power engine, is therefore an
expansive engine, in which the expansion is obtained simply by the
arrangement of the parts, without having recourse to any special appa-
ratus, such for example as a slide or other valve or cock.
It is obvious that in the case of an engine already made the degree of
expansion can only be varied by the addition of a special apparatus of
the kind herein-before referred to, which apparatus may be caused to

page_text: operate either so as to cut off the admission of the motive fluid into the
space between two consecutive flaps or vanes before that space is filled
with fluid at the full pressure (which would simply reduce the mean
pressure of the fluid without acting as an expansion, properly so called),
or to change the position of the inlet aperture or port H and the outlet.
or exhaust K in relation to the circular arc m, m³, of the cylinder. By
placing the aperture H nearer to the point m¹ the fluid remains longer
in the cylinder and the expansion is prolonged, whilst by removing the
aperture H further from the point m¹ or the aperture K further from the
point m, the fluid remains a shorter time in the cylinder, and the
expansion is diminished.
In the case of an engine about to be constructed the expansion may
be carried to the degrce desired by modifying the positions of the
apertures H, K, by changing the number of the flaps or vanes, and by
making the curve n, p, q, of a suitable form. If steam be the motive
fluid employed for this engine, a steam jacket may be applied to the
cylinder, as shewn in the Drawing, which has the known effects of that
arrangement in ordinary expansive steam engines.
The engine may be made condensing by placing the outlet or exhaust K
for the steam in communication with a condenser.
This engine, employed as a motive-power engine, possesses undeniable
advantages over all known engines, which recommend its employment
for a number of purposes. Its power is considerable relatively to its
small compass, and its consequent light weight. This result is due to
the high velocity of which the motive fluid is susceptible in traversing
the cylinder.
In motive-power engines in which the piston has a reciprocating to-
and-fro motion the velocity is limited to a maximum of from ten feet to
eleven and a half feet per second, which produces considerable strain on
the working parts of the engine. Such engines are subjected to alternate
tractive and compressing strains, which act principally on the joints with
a tendency to produce looseness or play, and by causing the parts to
strike against each other to destroy them. In those engines the inju-
rious spaces which are due, as is well known, to the play or clearance for
the piston at the end of each stroke, and to the spaces formed by the
steam pipes from the face of the slide valve to the cylinder ports,

page_text: occasion a considerable expenditure of fluid when the engines make a
large number of revolutions per minute, which is in most cases necessary
when the piston works at a speed of from ten to eleven and a half feet
per second. In this improved engine, on the contrary, as the piston has
a continuous circular motion, the motive fluid may traverse the cylinder.
at a much higher velocity, or, say, from twenty to forty feet per second,
or even more in the case of engines of a large diameter, whence a con-
siderable reduction in the weight of the engine per unit of working
power is obtained. Moreover by this engine a most remarkable improve-
ment is effected, videlicet, the working without any injurious space. The
whole of the motive fluid introduced operates in effecting the displace-
ment of the flaps or vanes, or, in other words, in producing power. As
also the passage of the fluid in traversing the cylinder is perfectly con-
tinuous all back pressure and sudden changes in the direction, section,
and velocity to which ordinary engines are subjected, and which are
prejudicial to the advantageous employment of the power of the fluid,

page_text: surface of such piston, and caused to open out or protrude therefrom as
required, for the purposes herein-before described.
In witness whereof, I, the said John Henry Johnson, have to this
my Specification set my hand and seal, this Tenth day of March
One thousand eight hundred and seventy-four.
J. HENRY JOHNSON. (L.S.)