Improvements in Rotary Engines.
Year: 1896

page_text: Date of Application, 19th May, 1896-Accepted, 8th Aug., 1896
[Communicated from abroad by ELMER PARKER HOWE, of Exchange Building,
53 State Street, Boston, Massachusetts, United States of America, Counsellor
at Law.]
Improvements in Rotary Engines.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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 rotary engines.
In the accompanying drawings which illustrate a steam engine with a variable
cut-off constructed according to the invention,
Figure 1 is a sectional elevation of the engine upon the line A A. Figure 2, and
Figure 2 is a vertical transverse section on the line B B Figure 1.
Similar figures of reference refer to similar parts in both views.
The outside casing 1, of any desired length and diameter, is made from suitable
metal and has attached to or formed upon it stands or feet 2, which support the
machine in the preferred position. The interior of the casing is made truly
cylindrical and to its ends are fitted and secured by suitable bolts the front and
back heads 3 and 4. To the interior of the casing there are fitted the rings 5
and 6, whose inner edges are bevelled, as shown by Figure 2. The ring 5, is firmly
fixed in position by pins (not shown) which pass through the sides of the casing
and ring, and the ring 6 is held in place by the back head when said head is in
position. Between the angular or bevelled edges of the rings, 5 and 6, there is
fixed by pins (not shown) a segment of a ring 7, one of whose ends is bevelled or
inclined as shown by Figure 1. Also fitted to slide between the angular or
bevelled edges of the rings 5 and 6, is a segment of a ring 8 having one of its ends
inclined or bevelled to fit the inclined or bevelled end of the segment 7, and also
having gear teeth formed upon its back. Fitted to a suitable bearing in the casing
is a shaft 9 with a toothed pinion, formed upon or secured to it, and the teeth of
said pinion correctly intermesh with the teeth of the segment 8, so that by the
operation of a crank or other handle on the end of the shaft 9, the segment 8, can
be reciprocated through the vacant space between the ends of the segments 7 and 8.
The pinion shaft 9 passes through a suitable gland 10, formed upon the front head,
as shown by Figure 2. The segment 8, forms the variable cut-off and when its
inclined end is brought into intimate contact with the inclined end of the segment 7,
it also acts as a stop valve.
To the interior of the rings and segments there is fitted the motor ring 11, which
is free to revolve therein, but when so revolving is substantially steam tight; and
on the outside of said ring, between the front head and the ring 5, are formed gear
teeth 12, as shown by Figure 1. A power shaft 13, is fitted to revolve in bearings
formed below the motor ring in the casing 1 and in the front head 3, where the
shaft passes through a gland 14. Fixed upon the shaft is a toothed pinion which
intermeshes with the gear teeth of the motor ring and causes the power shaft to
revolve when said ring is in motion. Inside of the motor ring, there is firmly fixed
to the front and back heads by the bolt 15 a block 16, whose lower surface makes
contact with the interior of said ring for about one-third of its circumference.

page_text: This block is provided with a groove on the side next the back head into which
groove project the ends of pins fixed in said head, so that the block can be adjusted
radially with reference to the interior surface of the motor ring, but cannot have
its angular position changed. This adjustment is for the purpose of causing the
motor ring to run steam tight between the block 16, and the rings 5 and 6 and
segment 7, forming the lower part of the bearing in which the motor ring revolves.
To provide an automatic adjustment for the same purpose a portion of the lower
part of the block 16 is cut away, and the swinging valve 17, is set therein so that
its free end can be pressed by springs 18 against the interior face of the motor ring.
This valve is hinged to the block 16, in the same manner as the pistons are hinged
to the motor ring, which will be hereinafter described.
The swinging pistons 19, 20 and 21, are hung upon the interior of the motor ring
and they swing back into recesses formed therein and substantially preserve the
continuity of the surface of said ring when they are passing under the block 16.
The joints upon which the pistons swing are made in pintle form, of two sizes, the
larger central part taking a bearing in the metal of the motor ring, and the smaller
ends taking a bearing in the collars 22, which in turn are fitted into counterbored
recesses in the edges of the motor ring, as shown in Figure 2. This combination
allows the pistons to swing freely and at the same time, when pressure is applied,
forms a perfect joint. Behind the free ends of the swinging pistons, ports 23 are
formed through the motor ring. Projections 24, formed at the back of the pistons
fill the ports when the pistons are swung back. To the back of the pistons are
secured light springs 25, which make contact with the motor ring as the pistons
swing back and by resisting the tendency of centrifugal force prevent the clashing
of the pistons against the interior face of the motor ring. These springs also
cause the inner sides of the pistons to bear against the lower portion of the
block 16, and preserve a steam tight connection between the pistons and the block
and they also act to start the pistons when the latter are free to swing towards the
centre of the casing.
The motor ring and the pistons are fitted to turn between the front and back
heads steam tight, and the edges of the pistons swing in intimate contact with the
heads so that the effective length of the pistons is the distance between said heads
and is constant. The free ends of these pistons are properly curved and fitted to
move steam tight upon the portion of the surface of the block 16, which corre-
sponds to the effective stroke of the pistons. This part of the block 16 is suitably
curved and the distance from the interior of the motor ring to the surface of said
block at the point where the free end of one of the pistons is resting, represents the
effective width of the piston at that point, which width is variable. By this it will
be seen that the curve of the surface of the block 16 (upon which the free ends of
the pistons bear during their active motion) in relation to the inner circumference
of the motor ring, governs the area and, of course, the power exerted by the pistons
to turn the motor ring at the different points of its revolution. This curve must
be varied to produce the best results when used for compressible or incompressible
fluids and also for different grades of expansion. In the present instance, the
curve of the bearing surface of the block 16, is substantially correct for the
expansion of steam about fifteen times from the initial pressure in the valve
chamber and cylinder at the time of cut-off, that is to say the curve is such that as
the steam pressure decreases by expansion, the piston area increases in the same
ratio, so that the effect on the motor ring will be constant.
The exhaust port 26, provided with a suitable outlet is formed in the back
head 4, as shown by the dotted lines, and its upper edge is located so that when
the back of one of the pistons is just disclosing it, the succeeding piston has moved.
under the influence of the initial pressure to the position indicated by the dotted
lines of the piston 19. This blending of the movements of the pistons under
pressure further preserves the uniformity of the turning effort exerted upon the
motor ring as the pistons succeed each other during the revolution of said ring..
The valve chamber 27 is formed in the casing behind the segment 8 and is

page_text: provided with a suitable inlet through which steam is introduced. It will be seen
from inspection of Figure 1, that the segment 8 being interposed between the valve
chamber 27, and the outer side of the motor ring, will when brought into contact
with the inclined end of the segment 7 close the passage from the valve chamber to
the ports formed through the motor ring, and that by moving the segment 8
in the direction which the motor ring revolves, the point of cut-off is made
later.
The part of the block 16, which does not make contact with the motor ring or
with the ends of the pistons is curved to engage with the inner faces of said piston
and gradually moves the pistons into the recesses formed in the motor ring against
the action of the springs 25, as shown by the piston 21.
The operation of one piston starting from the full lines of the piston 19, with
the segment 8 moved back to the dotted lines representing its front end is as
follows:
At the point designated, the port in the motor ring just discloses the variable
steam passage formed by the separation of the inclined ends of the segments 7,
and 8, so that the steam pressure commences to act upon the piston 19, before it
commences its inward swinging movement.
As the motor ring revolves the action of the steam pressure swings the free end
of the piston against the bearing surface of the block 16, until it reaches the
position shown by the dotted lines, when the steam is cut off, leaving the space
between the back of the piston and the interior of the recess full of steam at the
initial pressure. During this time the bearing surface of the block 16 and so much
of the pistou 19, as has swung beyond the interior circumference of the motor ring
forms an abutment against which the reaction of the expanding steam enclosed
between it and the back of the piston 20, causes said piston 20 to continue to act
until it discloses the exhaust port 26, when said piston is relieved from further
pressure, and the force to turn the motor ring is then entirely supplied by the
piston 19.
As the steam expands, the piston 19, swings further towards the centre of the
casing and its effective area increases as the steam pressure decreases until it nearly
eaches the position of the piston 20. When the piston 19, reaches the position of
the piston 20, the piston 21, has arrived at the starting position of the piston 19
and will operate in the same manner as the piston 19 as will also the other pistons
so long as the motor ring revolves.
When the pistons first commence acting against the surface of the block 16,
under pressure as shown by the piston 19, their operation upon the motor ring is a
thrust nearly parallel with their length, and they push the motor ring around as if
a lever were fulcrumed upon the block and, acting against their ends. As the
pistons swing out from the motor ring, their action upon said ring changes, and
were they permitted to swing diametrically out from said ring, they would act as
the buckets of a wheel and their pressure upon the block would be reduced to
nothing. The part of the block 16, against which the euds of the pistons act,
therefore, serves both as a fulcrum to move the motor ring, and as an abutment
gainst which the steam pressure reacts to produce rotation of the pistons and the
notor ring.
The action of the pistons as just described, causes their ends to bear against the
pintles and the surface of the block with a variable pressure, which is governed by
he steam pressure acting behind them, and as the pressure decreases their friction
lso decreases. This causes the ends of the pistons to be tight under all pressures
without excessive friction at some points of revolution.
As the thrust of the ends of the pistons is reduced, another portion of the inner
urface of the motor ring moves into the steam chamber and the pressure of the
team within this chamber acts to support the motor ring. As the steam pressure
reduced by expansion, there is more of the surface of the ring exposed to its
ction, so that by the combined action of the pistons and the pressure, the weight
f the motor ring, when it is revolving, is at all times substantially removed from

page_text: its bearing in the casing. This is true without reference to the position of the
cut-off, for the longer the initial pressure acts the greater is the pressure at
corresponding points within the motor ring to resist the larger surface exposed to
the direct pressure on the outside of said ring.
The motor ring can be made in longitudinal sections if found desirable, with the
joints in the thick parts between the recesses into which the pistons fit.
To the outer end of the power shaft, pulleys or gear wheels may be attached to
communicate motion to any desired mechanism, and should it be necessary to
reverse the movements of this mechanism, an auxiliary shaft may be mounted at
the side of the power shaft and connected thereto by swinging gear wheels,
preferably friction wheels, in the usual manner.
The advantages of the construction herein shown and described are many and
important, the principal of which are:
First. The securing of the block between and to the centre of the front and
back heads largely reduces the leakage surface common to engines of this class, and
allows of the use of much lighter heads and at the same time ensures greater
rigidity of the sides which make contact with the edges of the motor ring and
swinging pistons so that said edges will run freely and at the same time fit
sufficiently close to ensure a good steam tight joint.
Second. The steam pressure being balanced upon both sides of the motor ring,
and there being no power shaft fixed thereto, the edges of the ring are prevented
from grinding upon either head under the effect of outside stress.
Third. The movement of the ends of the swinging pistons over the surface of the
central block is about one-half of what it would be if they operated against the
interior of the casing in the usual manner, and this reduces the friction and wear
of the engine; moreover the action of the pistons against the central block tends
to ease the weight of the motor ring and to cause it to revolve freely, while at the
same time the centrifugal action of said ring causes it to throw and hold the
lubricant in the requisite places.
Fourth. The outer circumference of the motor ring moves the parts therein past
the valve at a high rate of speed and produces a square cut-off, and there being no
waste due to clearance, the best possible result from expansion is attained; and
the increasing effective area of the pistons renders it possible to obtain with
a lower rate of piston speed the same benefit from a high degree of expansion
as is now obtained by the use of complicated compound engines of the best
class.
Fifth. When the motor is used for service in steam boats the weight will be
placed low and if desired several motors could be geared tandem fashion to the
auxiliary shaft, and while the gyroscopic action of the revolving motor ring would
counteract the tendency to roll, the regular efficiency of the power applied
to the propeller at all times would increase the steadiness of motion, and the
perfect balance of the motor ring would prevent injurious results from racing.
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: In a rotary engine, a casing, a central abutment, suitable heads fixed to the
ends of said casing and abutment forming a rigid structure, an independent motor
ring fitted to revolve therein substantially as described, pistons mounted on said
ring and acting against said abutment to revolve said ring, and inlet and outlet
passages to admit and exhaust the motive fluid to and from said pistons, all
operating substantially as shown and described.
2. The swinging pistons mounted on the motor ring and having projections to
enter the inlet ports, in combination with a segmental sliding valve interposed
between the casing and motor ring and suitable gearing to slide and hold said
valve, whereby the motive fluid can be admitted to act upon the pistons for any
desired part of their active motions, substantially as described.

page_text: 3. The central abutment against which the pistons act to revolve the motor ring,
said abutment having a surface so curved with reference to the interior
circumference of the motor ring that the effective area of the piston increases in
the same ratio as the fluid pressure decreases after the time of cut-off, substantially
as described.
4. In a rotary engine, a casing, a central abutment, suitable heads fixed thereto,
a motor ring fitted to revolve in the casing and having gear teeth on a portion of
its outer circumference, swinging pistons mounted on the ring and acting against
the abutment to revolve said ring, a power shaft mounted in said casing, and
having a suitable gear wheel thereon to connect it to said ring, and inlet and outlet
passages to admit and exhaust the motive fluid all operating substantially as shown
and described.
5. A rotary engine constructed substantially as described with reference to the
accompanying drawings and operating as specified.
Dated this 19th day of May 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.