IMPROVEMENTS IN HIGH AND LOW PRESSURE EXPANSIVE CONDENSING STEAM ENGINES POR MARINE AND OTHER PURPOSES
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Henry Turner at the Office of
the Commissioners of Patents, with his Petition, on the 3rd August
1869.
I, HENRY TURNER, of Hazel House, Plaistow, in the County of
Essex, Engineer, do hereby declare the nature of my said Invention
for "IMPROVEMENTS IN HIGH AND LOW PRESSURE EXPANSIVE CONDENSING STEAM
ENGINES POR MARINE AND OTHER PURPOSES," to be as follows:-
This Invention has for its object the use of steam, first as high-
pressure steam, and afterwards expansively, in such manner as to obtain
therefrom the greatest amount of useful effect, whilst the arrangement
adopted admits of great lightness in the working parts of the engines.
This Invention consists in the construction of steam cylinders. with a
cylindrical recess at each of their ends, and of the pistons of the cylinders
with a cylindrical projection at each side, such projection corresponding
nearly in size but being actually rather. smaller than the recess, so that
between the recess and the projection a small annular space is always
left for the purpose of supplying that portion of the cylinder beyond
the recess with steam to be used expansively. By this arrangement
high-pressure steam may be introduced into the recess to commence the
stroke of the piston, and a portion escaping through the annular space-

page_text: becomes reduced in pressure so as to be used expansively. The high-
pressure steam within the recess and the steam that has passed through
the annular space acting separately but in the same direction force
the piston for about one-fourth of the length of its stroke, and then
intermixing complete the travel of the piston, so that in fact that which
in existing high and low pressure compound engines has has to be done
by two cylinders is by this improved arrangement effected in one cylinder,
and therefore the connecting passages are entirely dispensed with, the
result being greater compactness, lightness, and saving of fuel.
In carrying out this Invention it is proposed to make the steam
cylinders of such a length as to allow for the travel or stroke of the
piston, for the usual depth of the piston, and for the clearance at each
end; and in addition cylindrical recesses are formed in the steam
cylinders, one at each end of the same. These recesses are capable of
containing such a quantity of high-pressure steam as may be determined
upon, as for example, say, in or about the proportion of from three to
four tenths of the area of the diameter of the steam cylinder, and about
one-fourth of the length of the stroke. The piston has two cylindrical
projections, one at each side, which projections are of a length corre-
sponding nearly with that of the recesses herein-before mentioned. The
projections do not quite fit the recesses, but have an annular space
which will allow the passage of a quantity of steam sufficient to supply
that portion of the cylinder beyond the recesses with steam of a reduced
pressure, the steam having expanded during its passage through the
narrow space to a pressure of not many pounds above that of the
atmosphere, as, for example, say, from five to ten pounds pressure per
square inch. The recesses at each end of the steam cylinders are made
slightly taper, so as to insure the projections on the piston clearing
properly, and also with the object of supplying an increasing quantity
of steam as the piston is gaining speed in its advance towards the centre
of its travel. The admission of steam takes place only through steam
openings which are made at the further end of each recess in the
cylinders; there are two other openings, one at each end of the
cylinder. These openings allow the exhaust steam to escape into the
condenser after such steam has done its duty in the cylinder. The steam
openings at the further end of each recess serving for the admission of
steam act also as exhaust passages to the condenser for the expanded
steam left in those recesses. No steam can enter the cylinder but that
which is admitted by the openings at the further end of each recess, and

page_text: which is always cut off by the expansion valve before the projecting
cylindrical parts of the pistons have travelled past the inner ends of the
recesses. Each cylinder is fitted with a slide valve for the admission of
steam, and with lap to cut off the supply at about half the stroke of the.
piston. The valve also allows the exhaust steam that has done its duty
in the cylinder and its two recesses to escape into the condenser. The
slide valve is worked by link motion in the usual manner. Each steam
cylinder is likewise provided with an expansion valve, which always cuts
off the supply of steam before the projecting portions on the piston
have travelled beyond the recesses at each end of the cylinders. This
expansion valve is worked by a suitable gear capable of varying the
cut-off.
The mode of action is as follows:-The expansion valve at the
beginning of the piston's stroke is at its half stroke, and is therefore
full open. The slide valve is also open to steam with the usual lead.
The steam enters the bottom part of the recess in the cylinder and
acts upon the projecting part of the piston with full high-pressure force;
at the same time a suitable quantity of steam will escape all round this
circular projection, and will supply that portion of the cylinder beyond
the recess with steam of a reduced pressure from that in the recess,
and will force the outer portion of the piston during about one-fourth
of its stroke with what may be termed low-pressure steam. When the
piston has travelled to about one-fourth of its stroke the steam is cut
off by the expansion valve, and the projecting part on the piston leaving
the recess allows the high-pressure steam in the recess to mix with the
low-pressure steam in the cylinder beyond the recess, and the whole
steam to work expansively during the remainder of the stroke. It will
be observed that the vacuum acts during the whole of the stroke on the
entire area of the piston. This mode of using high-pressure steam is
applicable to all direct-acting engines with vertical, horizontal, or
inverted cylinders, and for engines with oscillating cylinders.