MENTS IN ROTARY ENGINES
Year: 1881

page_text: LETTERS PATENT to Henry Thibalt, and Thomas Hawkins, of the City and
County of San Francisco, State of California, United States of America,
COMPLETE SPECIFICATION filed by the said Henry Thibalt and Thomas
Hawkins at the Office of the Commissioners of Patents on the 5th May
1881.
HENRY THIBALT and THOMAS HAWKINS, of the City and County of San
16 IMPROVE-
Francisco, State of California, United States of America, Machinists.
MENTS IN ROTARY ENGINES."
Our Invention relates to certain improvements in rotary engines, and it has for
its object an improvement in the construction of the case within which the pistons
move and in the arrangement of the steam and exhaust ports and also improved
construction of the pistons and their actuating springs.
It further relates to a novel construction of spring plates, which form a tight
joint where the pistons pass from one side of the case to the other, and to certain
improvements in packing the joints between the drum and the case.
A cut off valve is applied to our engine, so that steam may be used expansively
behind the pistons, and an auxiliary steam pipe having an independent throttle
valve opens into the steam chest, so that a continuous supply of steam may be
admitted directly to the cylinder or case, and the steam thus admitted may be
used to assist that which is employed expansively whenever the duty of the engine
makes it necessary.
The cut-off valve may be of any form, but we have shown it in the present case
as a rotary valve driven by suitable connections from the main-shaft, and having
an opening which admits steam as each piston reaches a point where.its work
commences, the steam being cut off at any desired point of the stroke.
The drum or case within which the pistons move is made with open sides, and is
provided with a simple rim to hold the adjusting screws of the packing rings, all
of which will be more fully described by reference to the accompanying Drawings,
in which
Figure 1 is a vertical section of our engine transverse to the shaft.

page_text: Figure 2 is a side view with section of steam chest showing rotary cut-off
valve.
Figure 3 is a vertical section taken through the axis of the shaft.
Figure 4 is a horizontal section taken through the axis of the shaft.
Figure 5 is an enlarged detailed view of one of the pistons.
Figure 6 is an enlarged view of a piston spring.
Figure 7 is a view of the elastic abutment plate.
A is the case of the engine; B is the drum within which the pistons slide
radially from the axis, and C is the shaft upon which the drum is supported and
which is turned to transmit power from the engine. The case A is made so as to
approach closely to the drum at two opposite points where the packing or abutment
plates D are inserted. These plates are broad, thin, elastic spring, plates, each
having a projection E, which enters a corresponding groove made across the inside
of the case, or in a block E', which is fitted to receive it. The plates D'are convex
toward the drum, but their elasticity causes them to be forced into a curve
corresponding with the interior of the case, so that they actually form a portion of
the case, being countersunk or fitted with projections at their edges so as to lie
flush with it, but their elasticity causes them to press against the drum so as to
make a perfectly tight joint while permitting the piston to pass them smoothly
and without too great friction. The edges of these plates lie diagonally across the
interior of the case, so that the pistons pass one "end before the other and never
strike the joint or junction squarely, thus preventing any jar, abrupt shock, or
undue wear at this point.
From the central point these plates form a regular curve outward to join the sides
of the cylinder or case to enable the pistons to be projected out from the drum and
present a surface to take steam. This space is a gradually widening one from the
centre of the plates D to the steam and exhaust ports similar to one which would
be produced by enclosing the drum in an ellipse, but the curve at the point where
the pistons are acted upon by the steam, that is, between the ports F, F¹, is that
of a true circle, so that the pistons are neither moving out nor in when under the
pressure of steam and are free from such pressure when they are so moving.
The ports F, F, instead of being slotted through the face of the case back to
the points where they receive or exhaust steam are simply openings made through
to the interior of the cylinder from the steam channels formed in the case, and by
this construction we avoid the unequal wear upon the face of the pistons which is
caused by their passing over slots at those points in their rotation where they are
being forced outward or inwardly by the form of the case.
The pistons are formed, as shown in Figure 5, like a sash, having the outside
and transverse bars G formed thicker than the panels or body of the pistons H.
By this construction we secure lightness, while leaving the edges thick enough
to receive the packing plates.. Shallow grooves I are made across the bars G and
also within the piston chambers of. the drum to allow the steam to enter freely
and thus prevent any atmospheric pressure behind the pistons caused by too close
a fit..
The springs J by which the pistons are forced out are coiled springs set at the
bottoms of the piston chambers having each end extended out and crossing each
other, as shown in the. enlarged view, Figure 6, so that the elasticity of the coils
will allow these ends to be forced completely down without injuring the elasticity
of the springs, and this gives a more elastic and enduring spring than a spiral,
and one which may be compressed into a smaller space without injuring its
elasticity.
When the pistons are forced in to pass the spring plate abutments at D, the
exterior edge of the frame G will form a tight joint with the slot in the drum in
which they move, to prevent any leakage of steam, and when they are in position to
receive the pressure of steam the central bars serve the same purpose...
The faces of these pistons are provided with packing plates or bars K, which are.
forced out by springs. In order to provide a tight joint at the edges where they

page_text: pass into and out of the drum we employ plates L, which are kept out to a bearing
by springs beneath them. These plates are narrower at their outer ends than their
inner ends, being tapered, as shown in Fig. 5, so that at a joint opposite the
central bar of the frame they are as wide as the full thickness of the frame, and
present an unbroken line to the channel within which the pistons lie when the latter
are in a position to receive steam pressure.
The packing of the joints between the edges of the drum and the case is effected
by the use of a ring M and a packing of hemp N, inside of which is a ring ◇ which
fits against the flange of the drum, while the other ring M serves to press the hemp
against the joint. The ring or rings are set up at any time when necessary by
means of set screws P from the outside of the case.
The face of the ring O is made flat where it fits against the drum, and its outer
periphery is of the same diameter as the side of the drum itself, so that the joint
between the drum and the case is just at the edge of the ring.
The edge of the case is bevelled so as to form an angle outward from the joint,
and hemp packing is inserted into the angular space formed between the ring O and
this edge of the case. The ring M is then forced down upon the hemp and thus
makes a tight joint.
In some cases it may be found desirable to employ only the hemp packing with
its single rim M. When this is done the edge of the drum may be slightly pro-
jected to form a flange, between which and the case the packing is retained. The
case A may be made with open sides for the purpose of putting in and taking out
the packing ring without the labor of removing the side. On the edge of the inner
rim of the sides are placed buttons or arms which are so pivoted or bolted to the
rim that they may be turned down in front of the packing ring, or turned back so
that it may be removed without obstruction. The screws by which the rings are
adjusted and made to fit pass through the ends of these arms, and when they are
turned down in front of the rings the screws may be turned to press against the
rings as much as desired. The screws by which the stuffing rings are set up pass
through lugs upon the edges of the rim.
The steain and exhaust channels within the case have in addition to the ports F
openings upon each side of the spring plate abutments E leading to the interior
of the case or cylinder, as shown. It will be seen that when steam is admitted into
the steam passages upon one side, and the exhaust passages upon the other side are
open to discharge steam, the steam will be admitted through its proper port F and
also through the corresponding abutinent port Q.
This produces an equal pressure upon each side of the pistons which are travelling
from the abutment to the steam port so as to balance them and relieve them of side
pressure while they are being expanded or forced out to be in readiness to take steam
at the proper steam port F.
The balance upon each side of the pistons which are moving inward upon the
exhaust side is also maintained in a similar manner by the ports F¹, Q being
connected through the main passage in the case.
That portion of the interior of the cylinder between the ports F, F1, where power
is applied to the pistons is, as before described, the true arc of a circle having the
shaft C as its centre. This arc is continued just to or beyond the outer edge of the
ports F, so that the pistons will have attained their full bearing before they receive
steam pressure.
A steam chest R at one side of the case receives steam from the boiler, and it is
admitted to the engine-case A by moving a valve S, this valve serving also to
reverse the engine by simply moving it to one side or the other so as to expose or
open the steam port through which it is desired to have the steam pass. In con-
nection with this valve we employ a cut off valve, by the use of which the admission
of steam may be regulated, so that it will follow the pistons under full pressure as
far as may be desired. This valve may be of any known or suitable form, but we
have shown it in the present case as being a circular disk T forced so as to fit upon
a corresponding seat U, this seat forming a partition or wall between the steam

page_text: chest and the cut off valve chamber V which receives steam from the boiler. This
.partition or seat has an opening a made through it, and the disk or valve itself has
as many corresponding openings b as there are pistons. This valve has a shaft c
extending out through the side of its chamber, and a bevel gear or pinion d upon
its outer end is engaged by the pinion e upon the vertical shaft f. Similar bevel
gears at its lower end and upon the engine shaft C serve to give it motion in unison
with the revolutions of the engine, so that the openings in the valve are brought to
correspond with the one in the seat just as each piston arrives at the proper point
to take steam. When the valve opening has passed the port in the seat the steam
will be cut off, and that which has been admitted will act expansively during the
remainder of the stroke.
The gear wheel upon the main shaft has a curved slot made in it, and a pin h
from the shaft enters this slot. When the engine is turning in one direction this
pin will press against one end of the slot and thus drive the cut-off valve to
admit steam at the right instant for that direction. When the engine is reversed
the pin will move to the opposite end of the slot, which is just long enough, so
that when in this position the cut-off will be operated properly for the reversed
movement.
A supplemental pipe i having an independent valve m leads from the main steam
pipe directly to the steam-chest, so that if the duty of the engine is increased
beyond what it can do with the steam used expansively, the valve m may be
opened and steam admitted directly to the engine to follow the full stroke in
addition to that which enters through the cut-off valve. The abutment plates D
are perforated, as shown in Figure 7, to allow steam to pass freely so as to balance
the pressure.
Having thus described our Invention, what we claim as new and desire to secure
by Letters Patent is,—
1. In a rotary engine having the drum B with its radial sliding pistons moving
within the case A, as shown; the steam channels within the case having the
independent ports F and Q, whereby steam is admitted to both sides of the piston
to balance them when they are moving out or in, substantially as herein
described.
2. The broad elastic plate D with its projecting rib or abutment E, said plate D
exerting a constant pressure to form a tight joint between the case and the drum,
and preventing noise and wear as the pistons pass, substantially as herein
described.
3. The double coil spring or cushion J beneath the pistons having the crossed
arms extending to the pistons to press them outwards, substantially as herein
described.
4. The pistons consisting of the frames or ribs G forming a close. fit within
their channels in the drum and the panels or body H, substantially as herein
described.
5. The pistons formed of the panels H and the ribs or frame Q, said ribs having
the transverse slots I to admit steam to balance the piston and counteract
atmospheric pressure, substantially as herein described.
6. In combination with the pistons G, H, as shown, the spring packing edge
plates L, substantially as herein described.
7. The packing for the joint between the drum and the case consisting of the
hemp or other soft packing N fitting the angular or V shaped channel and the
ring M to hold it in place, in combination with the set or adjusting screws at P,
substantially as described.
S. The hemp or other soft packing N with its compression ring M and set screw,
in combination with the fat faced ring O and its adjusting screw, substantially as
herein described.
9. The case A having the drum with its sliding piston rotating within it in
combination with the rotary cut off valve perforated, as shown, and moving upon a

page_text: seat having a slot or opening, through which steam may pass as each opening in the
valve passes it, substantially as herein described.
10. The rotary cut-off valve slotted as shown, and moving upon a seat having a
corresponding opening in combination with the shafts and bevel gears by which the
movements of the valve are continued, substantially as herein described.
11. The pin h upon the main shaft adapted to enter a segmental slot in the gear
wheel g which is loosely fitted upon the shaft, said pin driving it from either end,
and thus adjusting the cut off to operate when the engine is running in either
direction, substantially as herein described.
12. The engine A having the cut-off valve T, in combination with the
supplemental steam pipe i with its valve, said pipe leading directly to the engine
independent of the cut off, substantially as and for the purpose herein described.
In witness whereof, we, the said Henry Thibalt and Thomas Hawkins, have
hereunto set our hands and seals, this 26th day of March, A.D. 1881.
Witnesses,
FRANK H. BROOKS.
S. H. NOURSE.
HENRI IIDALL.
(L.S.)
THOMAS HAWKINS. (L.S.)