IMPROVEMENTS IN COMPOUND STEAM ENGINES
Year: 1885

page_text: I, HENRY CHRISTIAN LOBNITZ of The Slip Dock, Renfrew, in the County of
Renfrew, North Britain, Engineer and Shipbuilder, do hereby declare the nature
of my said invention for "IMPROVEMENTS IN COMPOUND STEAM ENGINES," to be as
follows, that is to say:-
My said Invention has for its object the construction of compound engines to
work with three or more stages of expansion in an improved manner, the improved
engines being compact and the parts conveniently arranged in relation to each
other.
In carrying out the Invention in the case of a triple expansion engine the
intermediate or second-stage cylinder is made annular and the high-pressure
cylinder is made centrally within it thus avoiding the extra height or length
required when the cylinders are arranged tandem. A single rod from the high
pressure piston and two diametrically opposite rods from the annular piston have
fixed to them a crosshead which is connected to one crank, whilst another crank is
connected to the piston rod of the low-pressure cylinder which is arranged in
the ordinary way. The high-pressure cylinder may be placed centrally within
the low-pressure or third-stage cylinder but it is preferable to place it within the
second-stage or intermediate cylinder. When the engines are made for four stages
of expansion the low-pressure cylinder is made an annular cylinder with the third-
stage cylinder within it, like the high-pressure and second-stage cylinders.
The annular piston in each case requires packing rings round both its inuer and
outer edges. These rings are pressed outwards and inwards respectively by helical.
metal springs placed radially and carefully adjusted before being put in their places
so as to require no subsequent adjustment by screws. The body of the piston is
formed with radial sockets which are made no larger than is required for inserting
the springs; and the sockets for the outer and inner springs are arranged
alternately with each other, whilst the intermediate parts are made solid so as to
leave the least possible spaces inside the packing rings, these rings being made so
that their inner surfaces touch or almost touch the solid parts between the spring
sockets. Piston packing of this kind requires to be carefully made but is extremely
simple and lasts and keeps efficient for a long time.

page_text: I, HENRY CHRISTIAN LOBNITZ, of The Slip Dock, Renfrew, in the County of
Renfrew, North Britain, Engineer and Shipbuilder, 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, that is
to say :-
My said Invention has for its object the construction of compound engines to
work with three or more stages of expansion in an improved manner, the improved
engines being compact, and the parts conveniently arranged in relation to each
other.
In carrying out my Invention in the case of a triple-expansion engine, the
intermediate or second-stage cylinder is made annular, and the high-pressure
cylinder is made centrally within it, thus avoiding the extra height or length
required when the cylinders are arranged tandem. The bigh-pressure cylinder
may be placed centrally within the low-pressure or third-stage cylinder but it is
preferable to place it within the second-stage or intermediate cylinder. When the
engines are made for four stages of expansion the low-pressure cylinder is by my
Invention made an annular cylinder with the third-stage cylinder within it, like
the second-stage and high-pressure cylinders.
The annular piston in each case requires packing rings round both its inner and
outer edges; and these rings have springs applied to them in a special and
improved manner hereinafter particularly described. The valves for distributing
the steam to the combined annular and central cylinders may be either slide valves
or piston valves, being modified from ordinary forms of such valves to suit the
arrangement of the cylinders and their passages; and when piston valves are used
they may be packed in the same way as the cylinder pistons.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append eight sheets of explanatory
drawings to be hereinafter referred to and representing examples of the main
parts of compound engines as made with my improvements.
Figures, 1, and 2, on sheet, 1, of the accompanying drawings are longitudinal
and transverse vertical sections of the cylinders and some other parts of a set of
inverted-cylinder triple-expansion engines suitable for driving the screw propeller.
Figures, 3, and 4, on sheet, 2, are vertical and horizontal sections of the cylinders
and some other parts of a set of inverted-cylinder quadruple-expansion engines
suitable for driving the screw propeller.
Figures, 5, and 6, on sheet, 3, are, respectively, a sectional plan and a transverse
vertical section of a set of triple-expansion marine engines baving the combined
first-stage and second-stage cylinders vertical, and the third-stage cylinder
diagonal.
Figures, 7, and 8, on sheet, 4, are respectively a sectional plan and a transverse
vertical section of a set of quadruple-expansion marine engines having the
combined first-stage and second-stage cylinders vertical, and the combined third-
stage and fourth-stage cylinders diagonal.

page_text: Figures, 9, and 10, on sheet, 5, are respectively a sectional plan and a transverse-
vertical section of a set of triple-expansion marine engines having the combined
first-stage and second-stage cylinders vertical with a pair of third-stage cylinders
placed diagonally on opposite sides.
Figures, 11, and 12, on sheet, 6, are respectively a sectional plan and a vertical
section of a set of quadruple-expansion marine engines with oscillating cylinders.
Figures, 13, and 14, on sheet, 7, are transverse and longitudinal sections of the
combined first-stage and second-stage cylinders forming part of a set of triplo-
expansion or quadruple-expansion engines suitable for a locomotive or other engine
with horizonal cylinders.
"
Figure, 15, on sheet, 8, is an enlarged sectional view of the two pistons for a
combined annular and a central cylinder, the left hand half of the figure showing
the arrangement and mode of application of the packing springs.
In the several drawings the same reference letters are used to mark the same or
like parts wherever they are repeated.
In every one of the examples shown in the accompanying drawings the high-
pressure or first-stage cylinder, A, is placed within a larger so as to form an
annular cylinder (or cylindrical space) B, for the second stage of expansion; and
in the case of each of the quadruple-expansion engines shown on sheets, 2, 4, and 6,
the third-stage cylinder, C, is in like manner placed within a larger cylinder so as
to form an annular cylinder, D, for the fourth stage of expansion. These arrange-
ments have all the advantages of what are known as tandem arrangements of
cylinders without the height or extreme distance from the crank shaft which the
tandem arrangement involves.
In the case of each combined first-stage and second-stage cylinder, a single
rod, R, from the high-pressure piston, P, and two diametrically opposite rods, S,
from the annular piston; Q, have fixed to them a crosshead, T, (figures, 6, 8, 10)
which is connected to one crank, whilst in some cases another crank is connected
to the piston rod, U, of the third-stage cylinder, C, which is arranged in the
ordinary way. When however the third-stage cylinder or cylinders, C, or the
combined third-stage and fourth-stage cylinders, C, D, are placed diagonally as
shown on sheets, 3, 4, 5, their piston rod or rods, U, may be connected to the same
crank as the piston-rods, R, S, of the combined first-stage and second stage
cylinders, A, B.
The annular piston, Q. (as shown enlarged in figure, 15) is fitted with packing
rings, M, N, on its inner and outer edges; and these rings are pressed inwards and
outwards respectively by helical metal springs, V, placed radially and carefully
adjusted before being put into their places, so as to require no subsequent
adjustment by screws. The body of the piston is formed with radial sockets
which are made no larger than is required for inserting the springs, V, and in the
modification shown in figure, 15, the sockets for the outer and inuer springs are
arranged alternately with each other, whilst the intermediate parts are made solid
and so as to leave the least possible spaces inside the packing rings, M, N, these
rings being made so that their inner surfaces touch or almost touch the solid parts
between the sockets for the springs. Where the overlapping slips, X, are fitted
for covering the divisions of the packing rings, M, N, recesses or depressions are
made for them in the body of the piston. The high-pressure or first-stage
piston, P, is in figure, 15, represented as having a similar arrangement of springs
applied to its packing ring. Piston packing of this kind requires to be carefully
made but is extremely simple and lasts and keeps efficient for a long time.
In the case of the annular piston, Q, the parts may be modified by making the
sockets for the springs, V, open through at both inner and outer ends, and so that
the springs, made of suitable length, may each bear on both the inner and outer
packing rings, M, N. The arrangement shown in figure, 15, however, has the
advantage that the springs may be separately adjusted for the inner and outer
packing rings,

page_text: The passages of the combined first-stage and second-stage cylinders, A, B, which
as shown on sheet, 1, for example may be formed partly in the same casting as the
outer cylinder and partly in a casting which comprises a cover for both cylinders;
or in any other convenient way, are brought to one port face, which in the example
referred to, is of a cylindrical form, and has working within it a piston valve, E, of
a peculiar form which will be understood from the drawings. The valve, E, is made
with four piston parts to work in contact with the port face; and openings between
each outer piston part and the next communicate with a central cavity, G, in the
valve, whilst the middle part of the valve between the two pairs of piston parts is
contracted so as to form an annular space, H, between the valve and the port face.
Steam has access to the valve casing at both ends of the valve, E, and when the
valve moves down finds its way into the upper port, I, of the first-stage cylinder, A.-
When the valve moves up the steam passes from the top port, I, into the cavity, G,
of the valve and thence into the lower port, L, of the second-stage cylinder, B,
finally returning on the next downward movement of the valve and passing through
the space, H, into the exhaust port, O. In a similar way but at alternate periods
the steam enters the lower port, J, of the first-stage cylinder, A, returns and passes
through the cavity, G, of the valve to the upper port, K, of the second-stage
cylinder, B, finally proceeding through the space, H, to the exhaust port, O.
In figure, 1, the low-pressure or third-stage cylinder, C, is represented as pro-
vided with a flat port face for a slide valve; it might however be provided with a
piston valve and corresponding cylindrical port face. In figure, 3, what may be
termed a compound piston valve, E, like that shown in figure, 1, and herein-
before described, is shown as applied to the combined first-stage and second-stage
cylinders, A, B; and a similar compound piston valve is shown as applied to the
combined third-stage and fourth-stage cylinders, C, D. In the drawings of most
of the other examples the distribution valves are not fully shown; but in each
case in which an annular and central cylinder are combined the distribution valve
may be a compound piston valve or a compound slide valve, an example of the latter
being shown in figures, 13, and 14.
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
1.In triple-expansion-and quadruple-expansion compound steam engines the
making of the second-stage cylinder annular and with the first-stage cylinder
centrally within it, substantially as hereinbefore described.
2. In quadruple-expansion compound steam engines, making the fourth-stage
cylinder annular and with the third-stage cylinder centrally within it, substantially
as heroinbefore described,
3.-In a compound steam engine with one or more annular cylinders the improved
piston packing appliances substantially as hereinbefore described with more particular
reference to figure, 15, of the accompanying drawings.
4. In compound steam engines in which cylinders for two stages of expansion
are combined as hereinbefore described, the combination with such cylinders, of
compound piston valves substantially such as are herein before described.
4