Multiple Expansion Steam Turbines.
Year: 1896

page_text: Date of Application, 8th Apr., 1896-Accepted, 20th June, 1896
COMPLETE SPECIFICATION.
Multiple Expansion Steam Turbines.
We, ROBERT HEWSON of No. 314 Montgomery Street, Machinist, NEIL
CALVIN WHYTE and LOUIS DE ROME, of No. 126 Main Street, Manufacturers
all in the City and County of San Francisco, State of California, U.S.A., 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 :-
Our invention relates to an apparatus or motor in which steam or other elastic
medium, under pressure, is employed, and which we call "a double multiple
expansion steam turbine."
It consists of a peculiarly constructed wheel with a series of buckets concentric
with the axis or shaft, into which the propelling medium is admitted under pressure
to act expansively and with reactionary force, and is conducted successively from
one series of buckets through stationary concentric chambers upon each side of
the wheel to the next interior buckets, and is finally exhausted from the last
chambers surrounding the shaft.
Referring to the accompanying drawings-
Figure is a vertical section taken through the plane of the axis of the shaft.
Figure 2 is a transverse section showing parts of the wheel and of the
corresponding steam chambers.
Figure 3 is a detail showing more clearly the arrangement of the wheel buckets
with relation to the chambers and the passages leading from one to the other.
Fig. 4 shows three enlarged sections a b c of the buckets.
In our invention, A is a shaft which is properly journaled and from which power
may be transmitted to drive any desired mechanism in any of the well known or
suitable ways. Upon this shaft is firmly keyed a disk or wheel B, which in the
present case is shown made thickest at the hub where it is secured to the shaft and
which gradually converges to a less thickness at the periphery.
This disk is provided with as many series of buckets co, c', c 2, c 3, c4, as may be
desired, and depending upon the diameter of the wheel, the power to be generated,
and the pressure of medium to be expanded.
These buckets are made U-shaped or curving, and with a central web so as to
reverse the motion of the impelling fluid, as plainly shown in Fig. 4.
The deepest
point is at the back of the curvature, and they are so disposed that the legs or
sides lie in the direction of the movement of the wheel.
As we design to employ the steam or elastic medium expansively, commencing
at the periphery with the bighest pressure, and finally exhausting about the center
of the wheel, we have shown the outside row of buckets made smallest, and each
succeeding row increasing in size as the energy of the steam becomes less.
These buckets are arranged upon opposite faces of the wheel or disk, and each
set is designed to receive the actuating medium, so that the pressure being balanced
from opposite sides, there will be little or no end thrust upon the shaft, which is
an important point where a heavy pressure is employed.
Outside of the wheel or disk is fixed a casing D which is properly secured and
supported, and which is bolted together in halves so as to fit closely upon each side
of the wheel or disk.
This casing is formed with a series of chambers E, E¹, E 2, E3, E 4, upon each
side, the outer one being adapted to receive steam under pressure directly from the

page_text: boiler, and the others serve as receivers into which the steam passes from each
series of buckets after it has performed its work in that series, and from which it
is again delivered into the next series of buckets, to act upon them in the same
manner and so on to the center or exhaust chamber.
The wheel or disk with its buckets in its opposite faces rotates between the two
opposing chambered casings, and by means of suitable annular packing rings
forming contact between the face of the wheel and the inner faces of the chambers,
sufficiently tight joints are made to prevent the steam from going through directly
between the wheel and its casing.
From the exterior initial receiver a steam port H is made through the thickness
of the metal between the chamber E and the inner face of the casing, this port
being made at such an inclination that it delivers steam into the outer legs of the
curved buckets of the first series so that the steam acts directly against the rear
curved portion of the bucket, and following the curvature around into the inner
leg, it discharges through passages I, the openings of which are in line with the
inner legs of the buckets, and at approximately the same inclination with the
passages H, so as to deliver the steam through these passages I into the next inner
chamber E.
The steam thus acts by direct pressure, and also by the reactionary force caused
by its passage around the curved bottom of the bucket so as to impel the wheel
forward, the steam escaping rearwardly through the discharge porte í and into the
next interior chamber E¹.
The steam expands in passing through the buckets and enters this second
chamber at a less degree of pressure, and from this chamber it passes through
similar ports H into the second annular series of buckets c¹ which are situated
interior to the first series.
Each chamber E', E 2, in succession has a larger area than the one exterior
thereto and the buckets d, e, e2 correspondingly increase in area so that as the
steam becomes less in pressure, the size of the buckets and passages, and the surface
exposed to the action of the steam is increased.
It will also be seen that by reason of the steam being first taken at the periphery
of the wheel, the steam is admitted under the highest pressure and the greatest
velocity upon that part of the wheel which is revolving at the highest speed, and
as the pressure and velocity of movement of the steam become less, it is delivered
successively into buckets on the wheel which are moving at a less rate of velocity
until it is discharged from the lowest pressure chamber into the exhaust chamber J
which surrounds the hub and shaft of the wheel.
From this exhaust the steam is finally discharged through a suitable pipe or
passage.
By this construction, the steam is received into the exterior annular chambers
upou each side of the rotary wheel or disk at the highest pressure used, and is
delivered therefrom into a corresponding series of annular reactionary buckets in
the wheel and simultaneously upon opposite sides thereof, thus perfectly balancing
the wheel and preventing any appreciable end pressure in either direction upon the
shaft, or any frictional contact between the moving parts, greater than is necessary
to keep the joints sufficiently tight.
From these buckets the steam escapes into a second interior annular chamber of
larger area, thus reducing the pressure of the steam and leaving the available
pressure in the exterior row of buckets equal to the difference between the pressure
in the outer chamber and the next interior one.
This pressure is again reduced as it passes through the next larger series of
buckets to the next interior chamber of still larger area, and by reason of the
larger area of the buckets the effective pressure of the steam upon the wheel is
kept up proportionately, until the pressure is reduced to the point where it is
delivered into the exhaust chamber, and the movement of this portion of the wheel
being much slower than that of the periphery, the decreased pressure will still be
proportionately effective in propelling the wheel.

page_text: Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is-
D
1st. A wheel mounted upon a shaft adapted to rotate upon its axis, U-shaped
buckets formed concentrically upon the faces of the wheel, and having central
dividing racks, a casing having annular steam chambers corresponding in position
with the annular buckets in the wheel and separated therefrom by a closed
diaphragm against which the face of the wheel rotates, inclined passages made
through said diaphragm from the steam chamber and adapted to deliver steam into
the outer leg of the U-shaped bucket, correspondingly inclined discharge passages
connecting the inner legs of the buckets with the next interior steam chambers,
whereby the steam delivered into the outer leg passes around the curvature with a
reactionary force and is discharged from the inner leg.
2nd. A wheel consisting of a disk mounted to rotate upon a central shaft, annular
rows of U-shaped buckets formed upon opposite faces concentric with the axis and
having central dividing webs, each row increasing in size over the next exterior
one, a stationary casing fitting against the opposite faces of the wheel having
annular chambers upon opposite sides, said chambers corresponding with the
annular rows of buckets upon the wheel, inclined passages formed in the faces of
the chambers so as to discharge into the outer arms of the U-shaped buckets,
corresponding passages coinciding with the inner arms of said buckets in each
annular row, and discharging therefrom into the next interior chambers of the case
successively, an exhaust chamber surrounding the shaft or hub of the apparatus
into which the steam is finally delivered, and means for discharging it therefrom, a
steam pipe or pipes connecting with the exterior chambers of the case whereby
steam is admitted thereto under a high and equal pressure and thence passes
successively through each row of buckets and chambers, upon opposite sides of the
wheel simultaneously.
T
For the Applicants,
GEDGE & FEENY,
60 Queen Victoria Street, London, E.C., Chartered Patent Agents.