Improvements in and relating to Rotary Steam Engines.
Year: 1898

page_text: Date of Application, 5th July, 1898
Complete Specification Left, 22nd Mar., 1899-Accepted, 29th Apr., 1899
PROVISIONAL SPECIFICATION.
Improvements in and relating to Rotary Steam Engines.
I, JOSEPH CRAWHALL CHAPMAN, Chartered Patent Agent, of 70, Chancery Lane,
in the County of London, do hereby declare the nature of this invention (which
has been communicated to me by Marten van Buren Howe, Mechanical Engineer,
of 41, Westford Street, West Gardner, Worcester County, Massachusetts, United
States of America), to be as follows:-
This invention relates to a rotary steam motor or engine, which has been
especially designed to provide a simple, inexpensive and efficient construction for
utilizing the full expansive power of steam, and which is capable of accurate
regulation.
A further object of this invention is to protect or jacket the steam spaces of
the engine so as to avoid cylinder condensation.
A rotary steam engine constructed according to this invention comprises a
cylindrical casing or shell having a core or drum mounted therein.
The core or drum is made hollow, and forms a steam chest to which steam
may be admitted for convenience, if desired, through a hollow main shaft.
The steam spaces of the engine are located between the core and the shell or
casing.
By means of this construction, the hollow cylinder or core not only acts as a
steam chest for supplying the steam spaces of the engine, but the hollow core will
also act as an internal jacket for the steam spaces of the engine. That is to say,
the heat of the steam in the rotary steam chest will be more or less transmitted
to the steam which is being used expansively, so that cylinder condensation will
be avoided.
To provide a further protection for the steam spaces, an external steam jacket
may be employed encircling the cylindrical casing or shell of the engine, and
the exhaust steam may be conducted off through the external steam jacket.
In rotary steam engines, which are designed to employ high pressure steam,
the protection or jacketing of the steam spaces is an important essential for efficient
working.
This is especially well accomplished in steam engines constructed according to
this invention, as the live steam contained in the rotary steam chest will warm
the inner walls of the steam spaces and transmit more or less heat to the steam
which is being used, while the external casing for the exhaust steam will protect
and keep warm the outer surfaces of the steam spaces.
The valves and gates co-operating with the rotary core or steam chest may be
arranged in two principal ways.
In the preferred construction, the rotary core or steam chest is provided with
one or more abutments which are inclined or cam-shaped on one side and straight
or plane on the opposite side.
Mounted in the casing to co-operate with the rotary core or steam chest are
one or more movable gates, which are arranged to move in and out substantially
radially with respect to the casing of the engine.

page_text: One or more inlet valves are mounted in the rotary steam chest, and are arranged
to admit steam from the steam chest to the spaces between each gate and the
plane face of one of said abutments.
The pressure of steam confined between a movable gate and an abutment of the
movable core will tend to rotate the core, and, during this rotation, the inclined
or cam face of the abutment will move the gate outwardly so as to force the same
out of the way to allow the passage of said abutment, bringing the parts back into
the position where steam will be again admitted in front of the movable gate.
Outlet ports or passages extend through the casing of the engine, preferably to
the external steam jacket before described, so that, when an abutment passes the
same, the steam will be exhausted, or allowed to escape.
The cut-off or inlet valves, which are mounted in the rotary core or steam chest,
may be of any desired type.
Where oscillating valves are employed, they may be journalled or pivoted in
the rotary steani chest, and have extending stems secured on which may be tappet
arms co-operating with fixed stops for opening said valves, and with governor-
controlled stops for closing said valves, the valves being maintained in their
opened or closed position by means of springs.
In a modified form of engine constructed according to this invention, instead
of employing gates movably mounted in the engine cylinder, the rotary core
or steam chest may carry the movably mounted gates, and these gates are
preferably pivoted to turn or oscillate, although they may be reciprocated in
straight lines, if preferred, to move them in out of the way of abutments or pro-
jections extending in from the casing of the engine.
In a still further modified form of engine constructed according to this inven-
tion, movable gates or abutments may be mounted both in the casing of the
engine and in the rotary core or steam chest thereof, and, instead of providing
oscillating or rotary inlet valves, gridiron or reciprocating valves may be employed,
which may be actuated by valve stems arranged to engage suitable stops or cams
as the rotary core is turned.
In the construction of rotary steam engines, it has been found exceedingly
difficult to maintain a steam-tight joint between a cylinder shell or casing and
a rotating core, but, in engines constructed according to this invention, this
difficulty has been overcome by employing a plurality of packing rings, one packing
ring being fixed to the cylinder casing, another packing ring being adjustably
mounted on the rotary core, and a third packing ring being secured in place
between said two packing rings and the wearing surface of the core.
The special advantages claimed for rotary steam engines constructed according
to this invention are that they are of strong, simple and inexpensive construction,
which may be run with comparatively little friction to use the full, expansive
power of steam; and a special point of advantage is to be found in the fact
that the steam spaces of the engine are so fully protected, not only from the
outside, but also from the inside, that cylinder condensation will be completely
avoided.
Improvements in and relating to Rotary Steam Engines.
I, JOSEPH CRAWALL CHAPMAN, Chartered Patent Agent, of 70, Chancery Lane,
in the County of London, do hereby declare the nature of this invention (which 5
has been communicated to me by Marten van Buren Howe, Mechanical Engineer,

page_text: of 41, Westford Street, West Gardner, Worcester County, Massachusetts, United
States of America), 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 a rotary steam motor or engine, which has been
especially designed to provide a simple, inexpensive and efficient construction for
utilizing the full expansive power of steam.
A further object of this invention is to protect or jacket the steam spaces of
the engine so as to avoid cylinder condensation, and to provide simple and efficient
means of regulation.
To these ends, this invention consists of the parts and combinations of parts,
as hereinafter described and more particularly pointed out in the claims at the
end of this specification.
In the accompanying two sheets of drawings, Fig. 1 is a transverse, sectional
view of a rotary steam engine constructed according to this invention. Figs. 2
and 3 are similar views illustrating slightly modified forms of construction. Fig. 4
is a partial end view illustrating one form of valve-operating connections which
may be employed, and Figs. 5 and 6 are detail sectional views illustrating con-
structions which may be employed for securing a steam-tight joint between the
rotary core and its casing.
A rotary steam engine constructed according to this invention comprises a
cylindrical casing or shell and a core or drum mounted therein.
The core or drum is made hollow, and forms a steam chest, to which steam
may be admitted through the hollow main shaft.
The steam spaces of the engine are located between the core and the shell or
casing.
By means of this construction, the hollow core or drum not only acts as a
steam chest for supplying the steam spaces of the engine, but said hollow core also
forms an internal jacket for the steam spaces of the engine, that is to say, the
heat of the steam in the rotary steam chest will be more or less transmitted to the
steam which is being used expansively, so that cylinder condensation will be
avoided.
Referring to the drawings and in detail, A designates the cylindrical casing,
which may be formed with a pedestal or base-plate A¹ in the ordinary manner.
Mounted in the casing A and carried by the main shaft B is a hollow core C.
The main shaft B is also bored out or made hollow, and may be connected at
either end to a steam supply pipe.
By means of this construction, the hollow core C will form a steam chest, from
which steam may be supplied to the steam spaces between the core and its casing.
Mounted in the core C so as to control the inlet ports 10 are cut-off or inlet
valves,
These cut-off or inlet valves may be either of the sliding gridiron type or of the
oscillating or rotary style.
The steam admitted through the inlet ports 10 is utilized expansively between
co-operating gates or abutments carried by the hollow core and its casing respec-
tively.
Fig. 1 illustrates a construction in which the outer surface of the core C is
made in the form of a double scroll so as to co-operate with sliding gates 12, which
are movably mounted in the casing A, and are normally forced in by means of
dash-pots 15, which are connected to operate said gates by means of bell-crank
levers 13 and connecting rods 14.
In order to shorten the travel of the sliding gates 12, the core C may be provided
with pivoted gates or abutments 11, which are arranged to swing in out of the way
of the gates or abutments 12 of the casing.
By means of this construction, it will be seen that, when steam is admitted
to the spaces between the movable gates 11 of the core and the sliding gates 12
of the casing, the core will will be turned or rotated, and when a pivoted gate 11

page_text: passes one of the gates or abutments of the casing, the same will be free to turn
or move in out of the way, as illustrated by dotted lines.
When steam is admitted to an inlet port 10, it will throw the pivoted gate 11
back into the normal position illustrated by full lines.
The exhaust steam from the steam spaces of the engine passes out through
exhaust ports 16, and, if desired a jacket F to receive the exhaust steam may be
formed between the casing A and an outer casing E.
From this jacket the exhaust steam may be conducted off through exhaust
pipes R, in the ordinary manner.
In an engine, as thus constructed, it will be seen that the steam spaces are
warmed from the inside by the live steam in the rotary core, and are also pro-
tected or jacketed by exhaust steam on the outside of the casing, so that very little
chance is afforded for cylinder condensation.
In some cases, instead of providing the casing A with movable gates 12, the
same may be provided with fixed abutments, and a construction of this character
is illustrated in Fig. 2.
As shown in this figure, the hollow core C, instead of having the form of a
double scroll, is made cylindrical, and the pivoted gates 11 mounted therein are
arranged to move in out of the way of fixed or stationary abutments 120 formed
integrally with the casing A, so that, by means of this construction, the sliding
gates 12 and dash-pots or other operating connections therefor may be dispensed
with.
In a still further modified form of construction, the swinging gates or abutments
of the core C may be dispensed with, and sliding gates or abutments 12 alone
employed, as illustrated in Fig. 3.
As shown in this figure, the sliding gates or abutments 12 are provided at their
inner ends with rocking pieces 120 for insuring a tight joint between said gates 12
and the scroll or cam surfaces of the rotary core, and instead of employing spring
dash-pots and connections for operating the sliding gates 12, said gates may be
forced in at the proper time by steam pressure.
-. To accomplish this purpose, each of the sliding gates 12 is provided with an
operating piston 30, mounted in a movable casing 31, which is free to slide in a
cylinder 32.
Steam for operating each sliding gate 12 may be supplied from a steam-
chest 33.
When the movable gates are forced into their normal position, an exhaust
passage from the shell or cylinder 31 will be opened, and the inlet passage from
the steam chest 33 will be closed, as shown.
When the sliding gate is moved outwardly, the piston 30 will first close the
outlet passage, and, as the same moves out to the end of its stroke it will abut
against projections 31" and carry the sliding casing 31 out with it, so as to open
the inlet port from the steam chest 33 admitting live steam pressure to force the
gate 12 back to the position illustrated.
The connections which may be employed for operating the cut-off or inlet valves
of the engine may be of any desired or approved construction.
As shown in Figs. 3 and 4, 34 designates the rotary or oscillating inlet valves.
The valve-gear for operating said inlet valves is preferably located in a chamber
between the rotary core C and the end pieces 1) of the casing A, as shown in
Fig. 4.
Secured on the ends of the stems of the valves 34 are pinions 35 which mesh
with a gear 36.
A coiled spring 37, as indicated by dotted lines, normally holds the inlet valves
closed.
The valve-stems are provided with tappets or arms 38 arranged to engage a
governor-controlled operating plate 39.
The operating plate 39 may be shifted through a rod 40 by any of the ordinary
forms of governors.

page_text: By means of this construction, the inlet valves will be promptly opened at the
desired time, the width of opening and the time during which the same remain
open being controlled by, the plate 39, thus providing a variable cut-off, which is
of efficient construction and produces accurate regulation.
In the construction of rotary steam engines it has been found exceedingly
difficult to maintain steam-tight joints between the cylinder shell and the rotary
core.
To overcome this difficulty, a plurality of packing rings may be employed, as
illustrated in Fig. 6.
One packing ring as 40 may be mounted in the cylinder casing, a second
packing ring as 41 may be adjustably connected to the rotary core, and a third
packing ring 42 may be loosely confined between the packing rings 40 and 41.
Where this form of joint is employed, the heads or end pieces D of the casing
may be dispensed with.
In its preferred construction, however, a single packing ring as 43 may be
employed, as illustrated in Fig. 5, said packing ring being set into the core C in
such a way that steam pressure admitted to the space between the cylinder head D
and the end of the core C will tend to force the packing ring 43 outwardly.
Changes can, of course, be made in the construction embodying this invention,
and certain features of construction may be used in different connections without
departing from the scope of this invention, as expressed in the claims.
It is not desired, therefore, that this patent should be limited to the forms or
proportions herein shown, but
Having now particularly described and ascertained the nature of my said
invention (as communicated to me from abroad) and in what manner the same
is to be performed, I declare that what I claim is;-
1. The improvements in rotary steam engines, substantially as herein described
and illustrated in the accompanying drawings.
2. In a rotary steam engine, the combination of a casing and a hollow core
journalled therein so as to form a steam chest and also act substantially as a
steam jacket, substantially as described. .
3. In a rotary steam engine, the combination of a cylindrical casing, a hollow
core journalled therein, and an exterior jacket for said casing, said parts being
arranged so that the steam spaces of the engine will be jacketed both from the
inside and outside, substantially as described.
4. In a rotary steam engine, the combination of a casing, a hollow core journalled
therein, inlet valves mounted in said hollow core. and means for operating said
inlet valves, substantially as described.
5. In a rotary steam engine, the combination of a cylindrical casing, a core
journalled therein, sliding gates mounted in said casing to co-operate with the
core, and connections for operating said gates by steam pressure, substantially as
described and illustrated in Fig. 3.
6. In a rotary steam engine, the combination of a cylindrical casing, a core
journalled therein and packing rings for securing a tight joint between the casing
and core, substantially as described and illustrated in the accompanying drawings.
1 1000
J. C. CHAPMAN.