IMPROVEMENTS IN ROTARY ENGINES
Year: 1884

page_text: I WILLIAM PHILLIPS THOMPSON Fel Inst P.A., of the Agency for Foreign
Patent Solicitors, 6 Lord Street Liverpool in the County of Lancaster, and
323 High Holborn in the County of Middlesex, Civil Engineer do hereby
declare the nature of the said invention for "IMPROVEMENTS IN ROTARY ENGINES
A communication from abroad by John Harrington of Caldwell in the county of
Sumner and State of Kansas United States of America, Engineer and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
An object of this invention is to economise steam or other analogous agency
employed in rotary engines, and to such end it is proposed at each stroke or
revolution of the pistons, and at a moment prior to the exhaust and to the
admission of live steam, to admit into the clearance space that is to say the space
occurring between the pistons and the abutinents, after the pistons have passed the
latter and just prior to taking in live steam from the boiler, a portion of the
expanded steam by which the pistons have been driven, whereby prior to taking
in live steam there shall be within the clearance space a steam pressure equal to a
portion of the pressure required to drive the piston and capable therefore of
relieving the otherwise required amount of live steam to an extent determined by
the cut off in which way it will be evident a much less amount of live steam will
be required than where the expanded steam back of the pistons is all exhausted at
a point back of the abutment.
A further object is to utilize the full force of the steam pressure against the
pistous without allowing it to exert a side pressure either directly or indirectly in
a direction radially or tangentially to the shaft with which the pistons revolve and
to such end an annular piston space having walls rigid with the casing is divided
by the rim-portion of a revolving piston-disk provided with side pistons which fill
said space transversly.
A further object is to balance the revolving abutment-disk in a rotary engine
both with reference to the steam pressure exerted against the face of the abutment
disk and with reference to such portions of the disk from which material has been
removed to form a piston pocket.

page_text: And to such end steam spaces are provided between certain inner working faces
of the abutment-disk and bearings, located at points between the face of the disk
and the shaft upon which the disk is secured and admit into such spaces steam
capable of exerting a pressure that shall counterbalance the steam pressures against
the face of the disk whereby there will be no undue friction occurring between the
said shaft and its bearings.
Also certain portions of the abutment-disk are removed to an extent proportionate
to the material removed to form the pocket whereby the disk shall be mechanically
balanced.
A further object is to provide certain improved details of construction in a rotary
engine having its shell composed of a duplex cylinder-that is to say, a shell having
its interior consisting of two equal segment cylinders all as hereinafter described
and claimed and illustrated in the annexed drawing in which:-
Figure 1 is an end elevation of a rotary engine embodying the invention and
similar to Fig 3. but partly in section on the line Z-Z Fig. 6, and showing the engine
in position for filling the clearance space with steam previous to exhausting the
same before discharging through the final exhaust ports.
Figure 2. is a top plan view of the engine with the gear wheels removed, and
showing the location of the bent steam pipes which supply steam, and which form
passages for steam balancing the steam pressure on the abutment-disk.
Figure 3. is an end elevation partly in section on the line v-v. Fig 6. with a part
of the disk broken away to show the port, said figure showing the engine in a
starting position.
Figure 4. is a vertical section taken on the line x-x of. Fig 3, and shows
the relative positions of the abutment-disk, dead-ring and the cylinder heads, and
also the formation of the final exhaust ports.
Figure 5. is a section taken on the line ¹-x¹ Fig. 3, but only through the
abutment disk.
Figure 6. is a horizontal section taken on the line y-y of Fig 3, and showing the
relative positions of the piston, the abutment-disks and their respective shafts
connected at one end by twin-gears outside cylinder, one of said shafts carrying a
belt wheel or pulley.
Figure 7. is a perspective view of the piston disk detached.
Figure 8. is a section of said disk on the line y¹-y¹ of Fig 7.
Figure 9. is a broken section of the inside hub of the cylinder-head, taken
through the steam port x²-x* of Fig 1.
Figure 10. a side elevation of the dead-ring and showing so much of it as
is concave to receive the piston disk.
The essential operative members of this engine include a rotary disk A, provided
with pistons and termed the piston-disk and a second rotary disk B, subserving the
functions of an abutment, and termed the abutment-disk in contradistinction to
the piston disk carrying the pistons.
These two disks are arranged face to face within the shell case or cylinder of the
engine and are rigid upon their respective shafts which latter are provided with
twin-gears C, meshing with each other in order that a rotation of the piston-disk
and its shaft shall cause a rotation on the part of the abutment-disk in a reverse
direction.
The general arrangement of the case or shell D, of the engine is that of a duplex
cylinder, that is to say its interior is in the nature of two cylinders intersecting
each other so as to form segments of equal cylinders whereby when the two disks
are respectively arranged in said segments of cylinders and each made with a
diameter corresponding to the greatest internal diameter of the cylinder segment in
which it revolves, a portion of each disk shall project from one cylinder-segment
into the other and thereby admit of a portion of the piston-disk being received
and working in an annular groove formed in and around the periphery of the
abutment-disk,

page_text: This duplex cylinder is closed at its ends by suitable heads D1 and D2 through
which the shafts of the piston and abutment-disks pass and both heads of that
portion of the cylinder containing the piston disk are provided upon their inner
faces at a point opposite the piston-disk with centrally located hubs D³ extending
up to the said disk and having their perimeter concentric with the interior of the
cylinder segment in which they are arranged in order to form an annular steam-
space E, for the pistons on the piston-disk.
The pistons A are located on opposite sides of the piston disk, and are made to
fit in the portions of the steam space unoccupied by the disk, with the radius of
curvature of their inner and outer sides respectively corresponding to the perimeter
of the hub and the cylindrical interior of that portion of the shell, in which, the
piston disk is fitted to revolve.
It will be seen under such arrangement that the hubs around which the pistons
revolve constitute portions of the shell or casing, and hence as the pistons move in
an annular steam space having its walls which inclose the pistons formed of the
stationary casing of the engine the expansive force of the steam exerted within
said steam space to drive the pistons will while acting in the direction in which the
pistons revolve have no other effect upon the engine and hence will be incapable of
affecting in any wise the balance of the piston disk.
Steam induction ports F, (see Figs 1, 3, & 6) into which steam is admitted from
suitable connection with the boiler are formed through the casing next the opposing
heads and disposed so as to intersect concentric steam grooves G. arranged in the
sides of the piston-disk, and adapted during the revolution of said disk to connect
these induction ports with short ports or passages H. that are formed through the
hubs D³ and located so as to discharge the live steam at the proper. moment into
the steam space back of the pistons.
In Fig 2. convenient means are illustrated for admitting steam to the steam
grooves in the piston disk the same consisting of an inverted T pipe I, connecting
the ends of its two arms by bent pipes I, the induction ports F which latter consist
each of a vertical passage fextending downward through a portion of the cylinder-
head, and then running laterally toward the piston-disk so as to form a horizontal
passage f¹ which during the revolution of the disk will intersect one of the steam
grooves in the latter.
These steam grooves formed in the sides of the piston-disk as shown in Fig 7
are of such length as to cut off the steam at one quarter of the working stroke or
revolution of the engine, but it will be obvious that the said grooves can be made
in such manner as to take steam during the entire stroke of the piston.
The abutment disk is provided in and around its periphery with an annular
groove B¹, in which the rim portion of the piston disk constantly projects the
width of said groove, being such that the piston disk while accurately fitting in
the groove shall be free to revolve about its axis in a direction reversely to the
revolution of the abutment-disk.
The piston-disk projects into the grooved face of the abutment disk to a degree
dependent upon the extent to which the two cylinders intersect or run into each
other and hence the depth of the groove is made proportionate to the extent to
which the piston disk will project into the abutment disk.
Thus at all times some portion of the piston disk will lie in the groove formed in
the abutment-disk, and in order to fill up the remaining portion of the groove
unoccupied by the piston disk so as to prevent the live steam admitted into the
space back of the pistons from blowing through at the sharp corners indicated
at 1 and formed at the intersections of the cylinders, the piston and the abutment
disk I provide a dead ring K. fitting within the groove in the abutment disk, and
secured by bolts or analogous means to or otherwise made rigid with the shell or
segment cylinder in which the abutment disk is arranged.
Of this ring (see Fig 10) a part proportionate to the extent of the piston disk
Occupying the groove in the abutment-disk is broken away, and the said ring while

page_text: :
fitting in the groove is made so as to in no manner interfere with the free rotation
of the abutment disk.
As these two disks intersect each other at the point where the cylinders, in
which they are respectively located, intersect a portion of the abutment disk the
abutment disk will project into the annular steam space around the hub D³; and
in order to adapt the abutment-disk to constitute an efficient abut-ment within said
steam space it is arranged so that at all times some portion of its face at each side
of the groove therein and consequently at each side of the piston disk working in
said groove shall extend into a concavity D³ formed in the perimeter of each one of
the hubs D³.
In this way the annular steam space traversed by the pistons is at a point on a
right line between the axes of the two disks filled by a portion of the abutment
disks and hence allow the pistons to pass the abutment disk, this latter is provided
in its periphery with a notch or pocket B arranged at such point in the disk that
during each revolution of the two disks it shall meet the pistons which latter will
fit in the pocket, when the pocket and the pistons are on a right line between the
axes of the disks.
From the foregoing construction it will be understood that steam from the boiler
enters the eduction ports or passages in the cylinder or casing thence passes into
the steam grooves in the side of the piston disks so long as these steam grooves are
intersected by the induction ports or passages and from thence passes through the
short ports or passages in the hubs and enters the steam space back of the pistons
at points between the pistons and the face of the abutment disk where it acts
directly against the pistons so as to force the same around in the direction indicated
by the arrow.
Prior to exhausting the steam through the exhaust ports which will be hereinafter
described, it is proposed to utilize sufficient of the expanded steam by which the
pistons have been driven to fill the clearance space between the abutment disk and
the pistons at the moment occurring after the pistons in their forward revolution
have cleared the abutment disk and just prior to the exhaust before taking in live
steam from the boiler, for such purpose at each revolution of the engine.
To such end is provided in each one of the heads of the shell or double cylinder
a port or passage L. which may be termed a relief or expansion port, and these
said ports are so arranged that before the pistons have completed their forward
stroke or revolution they shall pass said exhaustion ports into which latter the
expanded steam back of the pistons shall enter as soon as the pistons pass the said
ports, and passing through these ports or passages issue into the clearance space
prior to the admission of live steam therein.
These relief or expansion ports L, communicate at one of their ends with the
annular steam space at one side of the abutment which is at all times formed by
some portion of the abutment disk, and at their remaining ends communicate with
the steam space at the opposite side of the said abutment, the direction of one of
these ports being shown in dotted lines Figures 1 and 3.
The expanded steam entering these relief, or expansion ports after the pistons
pass the latter passes through said ports or passages while the pistons and the
pockets are passing a right line between the axes of the two disks and as the pistons
are in the act of leaving the pockets, the expanded steam enters the pocket from the
discharge end of the expansion ports which are located so as to communicate with
the pocket at the period of the operation of the engine.
This pocket is made of a greater area than the combined size of the pistons in
order that the pistons shall not strike the walls of the pocket during operation,
and also so that as the pistons leave the pocket, a passage shall be afforded for
expanded steam admitted into the pocket to pass into the clearance space occurring
between the pistons and the abutment disk after the pistons have left the pocket,
and up to the point of exhaust and of the admission of live steam from the boiler.
The clearance space L' will thus be filled with steam at a pressure corresponding
L

page_text: with the expansive force of the expanded steam determined by the extent of cut off,
that is to say, if for example the steam in the cylinder is cut off at 80 lbs pressure
at one half stroke the pressure of the expanded steam in the clearance space will
represent a pressure of nearly 40 lbs which would be equivalent to relieving the
required pressure of live steam one half, and thereby require but one half of the
live steam which if alone employed would be 80 lbs assuming the steam to be cut
off at 80 lbs pressure.
This mode of utilizing a portion of the expanded steam in place of simply
exhausting the same at or before the time the pistons are passing and clearing the
abutment will obviously effect a great saving in steam, and hence effect a like
saving in the cost of fuel required to run the engine, and also in case of any
condensation of steam tending to create a vacuum within the clearance space, the
admission of the expanded steam into the latter will entirely avoid the occurrence
of such objectionable feature.
The induction of live steam from the boiler should commence as nearly as
possible at the time of the exhaust, and in order to effect the latter in each side of
the abutment disk is provided a centrically arranged steam groove M. which said
grooves communicate with the exhaust ports N, that are formed in the heads of
the shell or double cylinder and arranged to meet the concentric steam groove in
the abutment disk.
These exhaust ports are shown in the sectional view Fig. 4 and also in dotted
lines Fig. 1 and communicate in any suitable way with a pipe for carrying off the
exhaust steam as for example, the lower ends of the exhaust ports or passages can
open into a hollow base for the engine from which said base a pipe M¹ may lead to
any suitable point.
The concentric steam grooves M, in the abutment disk are arranged so that at
or about the moment that steam from the boiler is admitted into the steam space
back of the pistons, said grooves shall be in communication with the discharge end
of the relief or expansion port or passage as illustrated in Fig 3 in which the
pistons are illustrated as having cleared the pocket in the abutment disk and also
one of the concentric steam grooves in the steam disk shown in dotted lines in
position to establish communication between one of the induction ports and one of
the ports formed in the hub, and opening into the steam space between the piston
and the abutment, it being understood at this moment in the operation of the
engine, communication is established between both of the induction ports and the
steam space between the abutment and each piston in order to drive the piston.
The steam pressure in said steam space against the abutment is equal to the
pressure exerted against the pistons, and as a result there will be an ojectionable
side pressure on the shaft carrying the abutment disk thereby causing undue
friction between said shaft and its bearings and consequently a loss of power unless
some means are provided to counterbalance such pressure.
And to such end is provided means for counterbalancing this pressure exerted
upon the abutment disk by the steam in the steam space which said means consist
in a steam space or recess N¹, formed in the periphery of each one of the two ring-
hubs O, which are respectively provided upon the inner faces of the heads of the
casing, and received in annular recesses formed in opposite sides of the abut-ment
disks at points around and concentric to the shaft on which the said disk is
mounted.
These steam spaces in the faces of the ring-hub between said hub and the
abutment disk revolving about the latter are arranged diametrically opposite the
portion of the annular steam space into which steam is admitted from the boiler
and are connected with said steam space by conveniently arranged steam passages,
as for example, by means of bent pipes P, leading from the annular steam space to
the steam spaces between the abutment disk and the hub.
These latter steam spaces are arranged between an interior portion of the
abutment-disk, and a stationary part of the casing at a point between the axis of
the abutment disk shaft and that portion of the steam space which is between the.

page_text: face of the abutment-disk and the pistons and in which steam is admitted to drive
the latter, and hence the pressure exerted by the expansive force of the steam
against the abut-ment-disk will obviously be counter balanced by the steam pressure
exerted in the said spaces between the abutment disk and the ring-hubs.
It will also be seen that whenever the steam pressure is reduced by reason of
expansion or otherwise in the annular piston space it will be correspondingly
reduced in the recesses thereby balancing the abutment disk so far as steam
pressure is concerned.
The cut-out or piston pocket in the perimeter of the abutment-disk will after
the first revolution of the engine be always charged with steam which in exerting
a pressure against the interior of the casing and the side and bottom of, the pocket
exert a pressure against the abutment disk in a direction lateral to the shaft on
which the abutment disk is secured, and hence have a tendency to cause undue
friction between the disk and the hubs around which the disk revolves, and also
between the shaft and its bearings.
In order to therefore counter-balance such pressure steam.spaces Q are provided
in the face of each one of the hub portions B' of the abutment disk and steam
passages R are arranged leading from the piston pocket to said steam spaces Q,
whereby steam from the pocket will pass into these spaces in the hubs of the
disk.
These steam spaces Q. revolve with the abutment disk and always occupy the
same relative position to the pocket, the steam admitted from the pocket into said
spaces will therefore at all times during the operation of the engine, serve to
counter-balance the pressure of the steam in the pocket against the abutment disk.
In order to ensure the admission of a suitable quantity of steam into the pocket
both for the purpose of supplying steam to the clearance space between the pistous
and the abutment-disk and to the spaces Q, in the interior of said disk on each side
of the disk a short steain groove S, is provided opening at one end of the pocket,
and running back from the latter as in Fig 1. so that after the pocket has passed by
the discharge end of the expansion port or passage, steam from the latter will for a
short period or so long as may be necessary continue to enter the pocket through
the medium of the steam grooves S, in the sides of the abutment-disk.
While the pistons are in the act of leaving the pocket and expanded steam is
entering the latter, there will necessarily be a pressure exerted against the outer
sides of the pistons, and hence a tendency to cause undue friction between the
inner sides of the pistons and the faces of the stationary hubs, around which the
pistons travel.
In order therefore to counterbalance such pressure, a portion of the face of each
hub is cut away so as to provide steam spaces T, at a point which shall be under
the pistons when the latter are leaving the pockets in the abutment disk, steam
being supplied to these spaces from the clearance space.
As a portion of the abutment-disk is necessarily removed in forming the piston-
pocket therein, the said disk is mechanically balanced by removing portions of the
material thereof from the sides at points on opposite sides of the shafts as for
example by forming grooves U. so that the material taken out to form such
grooves shall compensate for that taken out to form the pocket and the grooves
running into the same.
The foregoing illustrates the improvements as embodied in an engine of the
simplest construction, but it will be obvious that various changes could be made
without departing from the spirit of the invention.
As for example the admission of steam from the boiler to the annular steam
space could be attained by the employment of an out-side valve operated by an
eccentric or in any other suitable way.
Also if desired the engine herein illustrated could be made double, and so
arranged on the shafts that there shall be no dead points in its operation, and
further with any ordinary mechanical skill the engine can readily be made
reversible..

page_text: While having described steam as a means for propelling the pistons, it will be
evident that gas, or compressed air could be utilized as an operating agent, or that
the engine could be used as a water motor.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is-
1. The combination in a rotary engine of the revolving pistons and an abutment
with a passage for conveying expanded steam from a point in the piston space at
one side of the abutment to the clearance space at the opposite side of the abutment
at a moment prior to the admission of live steam from the boiler, substantially as
described.
2. The combination in a rotary engine, of the revolving piston-disk carrying the
pistons with the revolving abut-ment-disk adapted to constitute an abutment in
the annular steam space provided for the pistons and a passage substantially as
described for admitting expanded steam from one side of said abutment into the
clearance space at the opposite side of the abutment prior to the admission of live
steam from the boiler, substantially as and for the purposes described.
3. The combination substantially as described in a rotary engine of the revolving
piston disk having side pistons with the revolving abutinent disk and the expansion
port opening at its ends into the annular space for the pistons at points located at
opposite sides of the abutment which is formed of the abutment-disk, substantially
as and for the purpose described.
4. The combination substantially as described in a rotary engine of the revolving
pistons travelling in an annular steam space with an abutment and ports con-
necting the steam space at opposite sides of the abut-ment, and having their inlet
ends located in the path of the pistons whereby after the latter pass said ends of
the ports the expanded steam back of the piston shall enter the ports and pass
to the other side of the abutment after the pistons have passed the abutment,
substantially as described.
5. In a rotary engine the pistons fitted and arranged to work in an annular
steam space formed by four fixed annular walls of which two are in planes
concentric with the axis about which the pistons revolve, and the other two in
planes at right angles to the said axis where the expansive force of the steam
within said steam space shall not exert a side pressure either directly or indirectly
against the rotary shaft with which the pistons revolve, substantially as described.
6. In a rotary engine the revolving disk having its rim portion dividing the
annular steam space formed by four annular stationary walls substantially as
described and provided with side pistons which transversly fill the portions the
divided annular steam space at opposite sides of the piston disk for the purpose
described.
7. In a rotary engine a rotary disk provided with side pistons and having an
annular peripheral portion enclosed in an annular steam space which is in cross-
section entirely filled by the piston and the disk at the points where the pistons
occur in the disk, said parts being arranged so that the expansive force of the steam
in the annular steam space shall be incapable of exerting a pressure on the
periphery of the disk, substantially as described.
8. In a rotary engine the combination with a pair of fixed hubs located centrally
within the piston cylinder and having their faces concentric with the interior
thereof of the piston disk revolving between the inner opposing ends of the hubs
and extending beyond the circumference of the hubs to the inner wall of the
surrounding annular casing, and provided with side pistons which work in the
space between said hubs and the inner side of the piston cylinder, substantially as
described.
9. The combination in a rotary engine having duplex-segmental cylinders sub-
stantially as described of the rotary abutment-disk having a piston pocket, in its
periphery with a rotary piston disk intersecting the abutment disk and provided
with side pistons which work in an annular steam space formed in one of the

page_text: segment cylinders and centrally divided by the said disk, substantially as and for
the purpose described.
10. The combination of the duplex segmental cylinder with the revolving piston
disk provided with side pistons, a revolving abutment disk adapted to constitute
an abutment, substantially as described and the hubs located within one of the
cylinders for the purpose set-forth, and provided in their faces with concavities
into which the rim portion of the abutment disk extends, substantially as
described:
11. The combination substantially as described in a rotary engine of the
revolving piston disk carrying the pistons with a revolving abutment-disk having
a peripheral annular groove on which the rim portion of the piston disk is secured,
and a piston pocket formed in its perimeter to allow the pistons to pass said
abutment, substantially as and for the purpose described.
12. The combination in a rotary engine, of the revolving abutment-disk with
a steam space located at a fixed point between said disk and a hearing which is in
turn arranged between said disk and the revolving shaft on which the disk is
secured and means for admitting steam into said space to counterbalance steam
pressure against the face of the disk, substantially as described.
13. In a rotary engine the revolving abutment disk in combination with the
stationary hubs received in recesses formed in the disk between the shaft on which
the disk is secured and the face of the disk, the steam spaces formed in the faces of
the hubs, and passages connecting these steam spaces with the annular steam space
at or near the point where the steam is admitted into the latter, substantially as
described.
14. In a rotary engine the revolving abutment disk having in its periphery a
piston pocket and provided with an internal steam space communicating with the
pocket and located between a stationary hub through which the disk shaft passes,
and an inner face portion of the disk working upon said hub, whereby pressure
in the pocket shall be counter balanced by pressure in the internal space in the
disk, substantially as described.
15. In a rotary engine the revolving abutment disk provided with a piston
pocket in its periphery and mechanically balanced by grooves cut in its sides
substantially as described.
16. The combination in a rotary engine, of the duplex segment cylinder with
the revolving abutment disk, the revolving piston disk provided with side pistons
and with steam grooves in its sides the eduction ports arranged to intersect said
steam grooves, and ports adapted to connect said grooves with the annular piston
space, substantially as described.
17. In a rotary engine in which the piston-disk is provided with side pistons
working in an annular steam space a steam cavity formed in the bottom wall of
the steam space at a point opposite the clearance space, and arranged to commu-
nicate with the latter when the pistons are passing said cavity in order to resist
pressure against the outer sides of the pistons substantially as described.
Dated this 29th day of December 1884.