IMPROVEMENTS IN ROTARY ENGINES
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS IN
ROTARY ENGINES A communication from abroad by the Elastic Wheel and
Manufacturing Company of Waynesborough in the county of Augusta and
State of Virginia, United States of America
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 2nd March 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of Middlesex,
Patent Agent
IMPROVEMENTS IN ROTARY ENGINES [A communication from
abroad by the Elastic Wheel and Manufacturing Company of Waynesborough
in the county of Augusta and State of Virginia, United States of America.]
The Invention relates first to the construction of segmental exhaust valves and
their combination with a cam whereby their proper action shall be ensured when
the engine is running rapidly under low pressure. The Invention relates secondly
to the combination of the piston with a disc having solid tangential projections
between which the piston is secured and to an improved piston packing; and
thirdly to the means for shifting the reverse valve in reversing the engine.
The casing is an annular chamber in which the piston fits. The casing is
constructed of two halves bolted together and the inner rims are at sufficient
distance apart to allow a disc to work between them, the said rims having each an
annular groove to receive a ring packing to prevent the escape of steam at the
joint between the rim and the disc. This disc connects the piston to the engine
shaft. The piston is rectangular in section and is curved upon its upper and lower
sides to fit the steam chamber, and is provided with an opening to receive a lug on
the edge of the disc which has two tangential projections that enclose the ends of
the piston and form part thereof. The disc has two radial steam ports issuing
through these tangential projections on opposite sides of the piston and communi-
cating with the engine shaft which is tubular. The piston block is provided with
suitable packing hereafter described. The casing is constructed with protruding
077

page_text: valve chambers at two opposite points communicating with the steam chamber and
with the exhaust. Within the valve chambers are journalled oscillating valves
which form segments of the outer rim of the casing.
These valves are provided at their ends with flanges or lips curved to an arc
struck from the centre of oscillation of the valves, these lips being formed on the
rear or outer sides of the valves so that when the valves are oscillated, one of the
lips of each valve shall be across the annular steam chamber to form an abutment
for the steam. The sides of the valve chamber have recesses to allow the exhaust
to escape from the steam chamber through ports at either side of the joints between
the said valve and their seats, the seats being also provided with plug valves which
are to be connected together by suitable means for shifting the exhaust when the
engine is reversed. Under ordinary circumstances the action of the exhaust valves
will be properly secured by the force of the exhaust alone, but to ensure the proper
action thereof when the engine is running rapidly under low pressure, the journals
of the valves pass through the sides of the valve chamber and are connected to
levers whose other ends have rollers running in a cain groove formed in a disc
which rotates with the piston. The groove of the cam is concentric through a
little more than one-half of its extent while the remaining portion consists of three
short curves so that the proper action of the valves will be ensured under all
circumstances without any appreciable expenditure of force since the force of the
exhaust is sufficient to accomplish this object under normal conditions as stated.
Within the tubular engine shaft and the boss of the disc is fitted a reversing valve,
to shift which a clutch collar is fitted to slide upon a feather on the hollow engine
shaft, which collar has an internal spiral groove to receive a pin passing through a
slot in the hollow shaft and rigidly secured to the said valve so that when the
collar is made to slide upon the feather the pin will follow the spiral groove and
cause the valve to be shifted from one of the radial ports in the disc to the other,
and thus allow the steam to pass to the opposite side of the piston to reverse the
engine.
Suitable connections are to be formed between the collar and the plug valves
above mentioned so that the engine may be reversed by a single operation.
Suppose the piston to have just passed the one exhaust valve, the position of the
cam is such as to ensure the opening of the said valve so as to form an abutment
behind the piston with the end nearest thereto, and to allow the exhaust to escape
at the other. The concentric portion of the cam will ensure the said valve
remaining stationary during the next half revolution of the cam and piston, and in
the meantime the other valve will have been closed to allow the piston to pass, and
when the piston has passed it, it will form an abutment in the manner already
indicated for the first valve which will then be closed in turn.
In a single acting engine, the heads of the valve chambers are to be cast with
pieces which shall project within the said chamber in such manner as to form a
support for the abutting end of the valve when the latter is closed, and also to
prevent the passage of steam at that end of the valve.
The piston packing above alluded to is composed of two angular metal plates
which are adapted to be fitted together in rectangular form in a suitable recess
made around the block or around the ends thereof and held in contact with the
walls of the steam chamber by springs arranged between the said plates in
perforations formed through the block.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on
the 2nd September 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of Middlesex,
Patent Agent, "IMPROVEMENTS IN ROTARY ENGINES.' A communication from
abroad by the Elastic Wheel and Manufacturing Company of Waynesborough
in the County of Augusta and State of Virginia, United States of America
This Invention relates first to the construction of segmental exhaust valves and
their combination with a cam whereby their proper action shall be ensured when
the engine is running rapidly under low pressure. The Invention relates secondly
to the combination of the piston with a disc having solid tangential projections
between which the piston is secured, and to an improved piston packing; and the
Invention relates thirdly to the means for shifting the reverse valve in reversing
the engine.
In the accompanying drawings Figure 1 is a side elevation of the steam chamber
partly in section. Figure 2 is an end view of the engine. Figure 3 is a detail
showing the piston packing. Figure 4 is a diametrical section through the annular
steam chamber. Figure 5 is a section showing the reversing valve, and Figure 6
shows the valve chamber of a single acting engine. The same letters of reference
indicate corresponding parts in all the figures.
The casing is formed of two similar ring shaped shells A A' of cast metal each
with an annular recess a formed in its face of a depth equal to one half the width
of the piston so that when the sections are placed together face to face, the recesses
of the plates will form an annular chamber in which the piston fits. The inner rims
of the shells will, when the latter are so placed together, come opposite to each other
and be at sufficient distance apart to allow a disc C connecting the piston D to the
driving shaft E to work between them. A second and much smaller annular
groove a¹ in the faces of the inner rims receives a ring packing F preferably of rubber
by which the steam is prevented from escaping from the annular chamber through
the joint between the rim and the disc. The piston D is formed of a block of metal
rectangular in cross section and curved upon its upper and lower sides to fit the
steam chamber and provided with an opening to receive a projection on the periphery
of the disc while two tangential projections d enclose the ends of the piston and
form part thereof. The disc C is provided with two radial ports e e¹ issuing through
the tangential projections d on opposite sides of the piston and communicating with
the interior of the shaft E which is tubular. The piston block is provided with
suitable packing as shown. The shell sections A A' are so constructed as to form
together with a suitable plate or plates a protruding valve chamber G at two opposite
points on the casing communicating with the steam chamber and provided with
exhaust openings H. Within the walls of the valve chamber are journalled
oscillating valves L which are curved to correspond to the outer periphery of the
casing and form a rule joint with the stationary valve seats. These valves are
provided at their ends with lips which are curved to coincide with the arcs described
by the ends of the valves when moved about their journals. These lips are formed
on the rear or outer sides of the valves so that when the valves are moved to the
position shown in Figure 1, one of the lips of each valve shall be across the annular
steam chamber to form an abutment for the steam. The walls of the valve chamber
are constructed with recesses M at the sides of the valves L to allow the exhaust to
escape from the steam chamber through ports at either side of the joints between
the said valves and their seats, the seats being provided with plug valves M' which

page_text: are to be connected together by suitable means for shifting the exhaust when the
engine is reversed.
Under ordinary circumstances the action of the valves L will be properly ensured
by the force of the exhaust alone, but to ensure the proper action thereof when the
engine is running rapidly under low pressure, the journals of the valves are made
to project through the walls of the valve chamber and have levers N fixed on them
whose other ends have studs furnished with rollers which run in a cam groove n
formed in a disc which rotates with the piston. The groove n of the cam is concentric
through a little more than one half of its extent, while the remaining portion thereof
consists of three short curves connecting with the ends of the concentric portion.
With this construction the proper action of the valves will be ensured under all
circumstances without any appreciable expenditure of force since the force of the
exhaust is sufficient to accomplish this object under normal conditions as stated.
Within the tubular engine shaft E and the boss of the disc C is fitted a reversing
valve K as shown in Figure 5. For shifting this reversing valve K a clutch collar k
is fitted to slide upon a feather o on the hollow shaft E which collar has an internal
spiral groove to receive a pin o¹ passing through a slot in the hollow shaft and
rigidly secured to the said valve so that when the collar is made to slide upon the
feather, the pin will follow the spiral groove and cause the valve to be shifted from
one of the ports e e¹ in the disc C to the other and thus allow the steam to pass to
the opposite side of the piston to reverse the engine. Suitable connections are to be
formed between the collar k and the plug valves M' so that the engine may be
reversed by a single operation.
Figure 1 of the drawings represents the piston as just having passed the exhaust
valve on the left hand side moving in the direction of the arrow while the position
of the cam at same time ensures the opening of the valve as to form an abutment
behind the piston with the end nearest thereto and to allow the exhaust to escape
at the other end. The concentric portion of the cam will ensure the said valve
remaining stationary during the next half revolution of the cam and piston, that
is until the piston shall have passed the valve on the right hand side. In the
meantime the valve on the right hand side as shown by the position of its lever
and the cam in the drawing, will have been closed to allow the piston to pass, and
when the piston has passed it, it will form an abutment in the manner already
indicated for the other valve which will then be closed in turn. In a single
acting engine the heads of the valve chambers are to be cast with pieces which
shall project within the said chamber in such manner as to form a support for
the abutting end of the valve when the latter is closed, and also to prevent the
passage of steam at that end of the valve. This form of the valve chamber is
shown in Figure 6.
The piston packing above alluded to is composed of two angular metal plates
which are adapted to be fitted together in rectangular form in a suitable recess
made around the block or around the ends thereof and held in contact with the
walls of the steam chamber by springs arranged between the said plates in
perforations formed through the block, as shown in Figure 3.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is :—
1st. In a rotary engine, the segmental exhaust valves having segmental lips at
their ends in combination with the valve chambers having recesses at the sides of
the valves and a reversing valve located in the valve seat, substantially as shown
and described.
2nd. In a rotary engine, the segmental exhaust valves having their journals
projecting through the walls of the valve chambers, in combination with the
levers secured to the outer ends of said journals and adapted to be operated
by a cam which rotates with the piston, substantially as and for the purpose
set forth.
3rd In a rotary engine the segmental piston in combination with a disc having

page_text: tangential solid projections formed on its periphery between which the piston is
secured and radial ports issuing through said projections to the steam chamber,
substantially as shown and described.
4th In a rotary engine the reverse valve located within a hollow shaft and
provided with a pin which moves in a slot in said shaft, in combination with
a sliding clutch collar having a spiral groove into which the said pin projects,
and the disc having two radial ports substantially as and for the purpose
set forth.
5th. In a rotary engine the combination with the segmental piston of angular
metal packing plates adapted to be arranged in rectangular form in suitable
recesses made about the ends of the piston, substantially as shown and
described.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this first day of September, A.D. 1882.