Improvements in Rotary Engines.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Rotary Engines.
A communication from abroad by SAMUEL EDMOUR ST. ONGE CHAPLEAU, of
Ottawa, in the Dominion of Canada.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, & 6, Bank Street, Manchester,
both in the County of Lancaster, & 323, High Holborn, in the County of
Middlesex, Civil Engineer, do hereby declare the nature of this invention, and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
This invention relates to that class of rotary engines in which a rotary piston,
mounted eccentrically in a cylinder, is provided with radially sliding pistons or
abutments which bear constantly against the inner surface of the cylinder and
which, being carried around by the pressure of the steam, act to turn the piston.
The invention relates to various improvements in the details of construction,
particularly to a compound arrangement of cylinders by which the engine is enabled
to act on the compound system, that is, by passing the steam at diminished pressures
from one cylinder to another, and an arrangement of ports and valves by which
the engine is made reversible as to its direction of rotation.
In the accompanying drawings:-
Figure 1 is a longitudinal central section through a compound engine on this
plan.
Figures 2 and 3 are cross sections of the same on the line 2-2 and 3-3
respectively.
Figures 4 to 12 are views showing details of the engine as adapted for reversal.
Referring to Figures 1 to 3 :-
A A¹ A², etcetera, represent a series of cylinders arranged end to end in eccentric
relations to each other, their ends being flanged and bolted to division plates or
heads B B', etcetera, by which they are separated. The high pressure steam is
received primarily into the central cylinder A, and, after performing its duty
therein, is exhausted to the right and left through the other cylinders in succession.
The cylinders to the right and left of the centre are of successively increasing
capacity, those which bear the same letters being of equal capacity.
Each of the cylinders contains a cylindrical rotary piston, filling the same from
end to end. These pistons have a common central axis. Each piston is considerably
smaller than its containing cylinder and bears against the latter at one point only.
Each piston contains four radially sliding abutments, D D¹, etcetera, the outer
edges of which bear constantly against the inner surface of the cylinder, their
outer edges being provided with suitable packing to ensure a tight joint. The
two opposite abutments on each piston are preferably connected by one or more
intervening rods, d, so that, as the piston on one side is pushed inward in the
course of its revolution by the eccentric surface of the cylinder, it will force
outward the piston on the opposite side.
Each of the division plates or cylinder heads, B B¹, etcetera, is provided with a
series of ports, 66, leading therethrough from the cylinder on one side to that on
the other. These ports are arranged in a curved line eccentric to the cylinder, as
shown in Figure 2, and, on the side nearest the central cylinder, each division plate
is provided with a curved slot b', connected with the second series of ports. As
each piston revolves, it covers and uncovers the ports leading from its cylinder to
the next. The steam entering each cylinder occupies the crescent-shaped space
between the cylinder and piston, and, being confined in this space between the

page_text: point at which the piston touches the cylinder and the next abutment, it forces the
piston around. In the course of the revolution the piston reaches the groove b
which being uncovered by the piston permits the steam to pass from the cylinder
in which it has performed its duty to the next cylinder where it expands and
operates in like manner at correspondingly reduced pressure.
It is to be observed that the steam admitted to the central cylinder is divided
and passes to the right and left through the larger or low pressure cylinder.
The contact point of each piston with its cylinder is preferably 90° from the
next. In this manner pressure is applied to different pistons at different points in
their revolution, and the engine is caused to run steadily and without a tendency to
wear on one side more than on another.
The uppermost or end cylinders deliver the steam, as shown in Figures 1 and 3,
through openings in the cylinder into an exhaust chamber E, provided with a
discharge pipe.
The foregoing parts constitute a complete and operative compound rotary engine
adapted to run continuously in one direction.
If the engine is to be reversible it is only necessary to provide the first cylinder
with two steam inlets at different points and to provide each of the division plates
or heads B B', etcetera, with double ports arranged at diametrically opposite points
and with valves whereby either set of ports may be brought into action and the
others closed at will. The preferred details of construction to this end are shown
in Figures 4 to 11.
Figure 4 shows an end view of the central cylinder A, with the two steam
inlets a a', which will be controlled by suitable throttles so that one may be closed
when the other is open.
These ports open respectively into chambers a² and a³ in the cylinder, from which
ports a deliver the steam into the cylinder either on one side or the other of its
vertical axis, according to the direction in which the piston is to be driven.
Each of the division plates or heads B B', etcetera, is constructed, as shown in
Figures 6, 7, 8, 9, 10 and 11, with an internal chamber containing a flat sliding
valve F, occupying a central position and adapted to move in a diametric direction
to cover and uncover the ports. This valve is preferably, but not necessarily,
provided with the ports f³ in its corners, as shown in Figures 10 and 11.
On the receiving side, that is, the side next to the high pressure cylinder, the
plate contains two series of steam ports bb, located on opposite sides of the centre.
The two sets of ports are duplicates of each other, and each set corresponds
substantially in form and arrangement with the ports of the engine first described.
The ports and lead into the interior of the chamber of the plate, and, as the
valve F is moved to and fro, it covers the ports b and alternately, one set being
closed when the other is open. On the opposite or delivery side, the division plate
or head is provided with outlet ports and 63, (see Figure 9) for discharging
the steam from its interior into the next or low pressure cylinder. These ports
are arranged in duplicate on opposite sides of the centre. The division plate is
commonly recessed from one side to admit the valve, as shown in Figure 7, and the
recess closed by the application of a cap-plate, such as shown in Figure 9. The
delivery ports are, for convenience, formed in this cap-plate, which, bolted in place,
is, in effect, a part of the main plate.
The steam entering the ports bor b' passes through the internal chamber, that
is, through the space unoccupied by the valve F, and escapes through the ports b³
or 63, as the case may be, into the next cylinder. Each of the reversing valves F
is provided with an operating spindle F', projected from the exterior of the engine
so that it may be rotated by it. It is proposed to connect the entire series of
reversing valves with a single device or mechanism for moving them in unison.
But, as this is a mere matter of convenience and not of the essence of this
invention, it is deemed unnecessary to describe the same herein.
The series of pistons may all be bored centrally and mounted in a common
shaft, as shown in Figure 1, but it is preferred, as shown in Figure 13, to cast each

page_text: piston with a short shaft c in one end to project through the division plate into the
next cylinder to engage its piston, with which it may be connected by dowel
pins c', or otherwise. At the opposite side, each piston, except those at the end of
the series, will be provided with a cavity to receive the shaft of the adjacent
piston.
To prevent leakage of steam from one cylinder to the next, it is proposed to
provide each division plate with glands or collars 6, extending right and left into
the ends of the adjacent pistons, and provided with a ring to hold in place the
packing 68, which encircles the shaft.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondent, I declare that what I claim is :-
1. A rotary compound engine comprising two or more eccentrically arranged
cylinders, each containing an eccentric piston with radially sliding abutments, each
cylinder communicating with the next by a curved row of steam ports, substantially
as described.
2. A rotary compound engine consisting of the series of eccentric cylinders,
their pistons having coincident axes and radially moving abutments, the division
plates provided with duplicate ports for directing the steam from the high to the
low pressure cylinders successively, and a reversing valve substantially as shown,
controlling said ports.
3. In a rotary compound engine, the cylinders with their division plates, in
combination with the pistons, each having integral therewith a shaft projected
through the division plate to the next piston.
4. A rotary steam engine having the peculiarities of construction and operation
substantially as herein described and shown.
Dated this 5th day of January 1891.
WM. P. THOMPSON & Co.,
Agents for the Applicant.