Improved Rotary Engine.
Year: 1899

page_text: Date of Application, 28th Nov., 1899-Accepted, 20th Jan., 1900
COMPLETE SPECIFICATION.
Improved Rotary Engine.
I, JOHN HARRISON DARRAGH, of No. 947, Pine Street, Oakland, County of
Alameda, State of California, United States of America, Pattern-maker, 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:
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The object of my invention is to produce an engine in which a piston carried
by a rotary shaft is caused to travel in an annular chamber by means of steam
or other medium under pressure, a rotary segmental abutment and means for
turning it so that at the instant the piston reaches the abutment the latter is
so turned as to allow the piston to pass and immediately closed behind it so that .
steam or other medium under pressure may be admitted through valves arranged
and operated for the purpose, while similar valves upon the opposite side of the
abutment are arranged to allow the escape of the steam after it has done its
work. The arrangement of the admission and exhaust valves so that their
positions may be reversed and the direction of motion of the engine reversed,
forms a part of this invention, together with improved means for packing the
movable joints to make them steam tight, and a means for connecting two or more
of the engines upon a single shaft to run in unison.
In the drawings, Fig. 1 is a vertical section of the engine transverse to the
shaft, showing the interior mechanism. Fig. 2 is a vertical section through the
longitudinal axis of the shaft. Fig. 3 is a detailed view of the piston and
packing plates. Fig. 4 is a detail of one of the end pieces in the piston.
The piston E is fixed upon the periphery of a thin dise C which in turn is fixed
upon the shaft B, and said shaft passes through the centre of the case A.
This case is formed of an exterior and interior portion separated so as to form
an annular channel 1) of sufficient depth and width to allow the piston E to
fit and move within it.
That portion of the casing interior to the annular channel D and through the
centre of which the shaft B passes, has a narrow radial slit or channel within
which the disc C is turnable, the outer edge of the disc just projecting so as to
connect with the piston E which it carries.
To prevent leakage of steam around the disc I have shown packing plates or
rings M having pressure springs N exterior to them and holding them close against
the sides of the disc C, as plainly shown in Fig. 2.
The piston consists of two sides which are fixed transversely upon the
periphery of the disc C, and have fitted between them the outwardly slidable
packing plates P overlapping each other where they meet in the centre, and at

page_text: the ends are packing strips Q which are also movable, being pressed outwardly
by springs R, so that all these packing plates fit closely within the annular
channel D and form a tight joint while the piston revolves within this channel.
A segmental abutment H is turnable in a cylindrical chamber in the casing A,
here shown in line above the shaft B, and intersecting the upper part of the
annular channel D, so that when the abutment H is turned to bring its cylindrical
periphery into the channel D, this periphery fits against the outer periphery of
the inner cylindrical portion of the casing and forms therewith a close joint
which prevents steam from passing back while it is in this position...
This abutment is grooved around its periphery and the edge of the disc C
fits into this groove so that there will be no independent end motion of the
two.
One side of the abutment has a curved segment cut out as shown at I and
when the segment is turned so that this cut away portion is coincident with the
annular channel D, the piston E will pass the abutment by reason of the space
allowed by this cut away portion.
In order to turn the abutment so that it will always bring this chamber or
cut away portion I in the proper position to allow the piston E to pass it, the
main shaft B and the abutment shaft J carry gears. K which intermesh so that
the two will always turn in unison.
Steam or other medium under pressure is admitted to move the piston and
with it the disc C and the shaft B to which it is fixed, by means of a valve V
which is opened as soon as the piston has passed, and the abutment H has
turned so as to close the channel behind the piston.
The two valves F F¹ may have passages c made through them and they are
cylindrical and fit in cylindrical chambers so that they may be turned, so that
one of the valves is connected with an exhaust passage G¹ and the other with C
which is closed.
By means of rocker arms connecting with the valves and a rod connecting
with a lever, the movement of the latter lever will reverse the positions of the
valves and F¹, so that when one is in position to connect with the exhaust
passage, the other is closed thereby.
Steam is admitted by means of a slide valve V movable in the steam chamber U
and adapted to cover one of the ports T T and simultaneously to uncover the
other.
This valve is connected by a rod a with the lever d so as to be moved in
unison with the movements of the valves F and F. Thus when the lever arm d
is moved in one direction, it withdraws the valve V so as to expose the port T
as shown in Fig. 1, and thus allow steam to pass into the abutment chamber
through the cut away portion I of the abutment, while the other port T¹ is
closed by the same movement of the valve.
The movement of the lever & which opens the port T, acts through the rod b
and the rocker arms of the valves F and F to turn the valve F¹ so that the
passage through it communicates with the exhaust, while the valve F is simul-
taneously turned so that it closes the exhaust passage G upon the side where the
steam passage T has been opened. This allows the steam to enter the annular
chamber D just after the piston E has passed the abutment H and the latter has
turned far enough to prevent the steam from passing behind it. Thus all the
steam pressure will act to force the piston E around the annular channel, and
as the exhaust passage upon the opposite side of the abutment is opened, any
medium remaining in the annular channel in front of the piston, will be forced
out as the piston moves.
The further turning of the abutment H will cut off the admission of the steam
at some point which may be regulated, and the steam may then be used expansively
from that point to the end of the stroke.
The power engine may be multiplied by connecting as many of the engines
to one driving shaft B as may be desired, and they may be so arranged that steam

page_text: will be admitted and exhausted in each engine either in unison or alternately
as may be desired.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1st. A rotary engine comprising a casing having an annular piston chamber, a
shaft extending axially through the chamber, a disc fixed to the shaft extending
into the annular piston chamber and having a piston with expansible packing plates
fitting and turnable within the annular chamber and a cylindrical abutment
turnable in a correspondingly shaped chamber exterior to the piston chamber so
that the cylindrical portion of the abutment projects into the piston chamber
contacting against its inner periphery and preventing the passage of steam when
thus turned, said abutment having a segment cut out at one side which is made
to coincide with the annular piston chamber at the instant when the piston arrives
80 that the piston may pass the abutment and in connection with these, valves
through which steam is admitted to one side of the abutment and exhausted from
the other side.
2nd. In a rotary engine having the piston carried by a central shaft and
revoluble in an annular piston chamber, and a rotary segmental abutment by
which the chamber is alternately opened to allow the piston to pass the abutment
and close after it has passed, steam and exhaust passages opening upon each side
of the abutment, valves by which either the steam passage and the corresponding
exhaust passage may be opened while the others are closed. and a lever and
connections by which the movements of these valves are made in unison so as
to reverse the direction of rotation of the engine.