IMPROVEMENTS IN COMPOUND STEAM ENGINES
Year: 1885

page_text: I HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co Patent Agents,
Southampton Buildings in the County of Middlesex, do hereby declare the nature
of my invention for "IMPROVEMENTS IN COMPOUND STEAM ENGINES" 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 steam engines of the class described in the specification
filed with my application for Letters Patent bearing date June 9th 1885 and
numbered 7045.
The said invention consists essentially in the combination with the high and
low pressure cylinders of a compound steam engine of a steam receiver and a
novel arrangement of valves for simultaneously cutting off the live steam at a
certain portion of the stroke, and allowing the steam in the high-pressure cylinder
to expand against the piston of larger area in the low-pressure cylinder.
In the accompanying drawing,
Figure 1 is a sectional view of an engine provided with improvements according
to this invention.
Figure 2 is a transverse section thereof showing a pipe for conveying the steam
from a receiver into the low-pressure cylinder.
Figures 3 and 4 are detached views of valves in different positions.
A is a high-pressure cylinder of any suitable dimensions and A¹ is a low pressure
or expansion cylinder located in the rear of the cylinder A.
In these cylinders are placed the pistons B and B', the latter piston within the
cylinder A¹ being of larger area than that within the initial cylinder A. C is the
rod to which the said pistons are connected.
Instead of exhausting directly from the high-pressure cylinder into the low-
pressure. cylinder, as described in the specification N° 7045 I exhaust into a
receiver M formed around the said high pressure cylinder, as shown in Figure 1,
and having a pipe M¹ leading therefrom to the valve chest M* of the low-pressure
cylinder.
With this construction I use ordinary slide valves N N¹; the valve N having
ports m³ m², and the valve N¹ the ports n¹ n³; and in connection with these slide
valves I employ the cut off valves O, O¹. The high and low pressure cylinders

page_text: are each provided at their ends with the steam ports o o¹ and o³ ³ respectively
which afford communication with the ports having the cut off valves O, and O¹. In
the low pressure cylinder is also formed the exhaust passage P, which registers
with the recess P¹ formed in the valve N¹.. With this recess P¹ are also adapted to
register the ports of o* formed in the low pressure cylinder.
With this form of engine I may use a compensating cross-head similar to that
described in the said specification instead of connecting the two pistons to the
same rod as shewn in Figure 1.
It will be seen from the above description that when the valve O is in the
position shown in Figure 4 the live steam which is admitted to the chest M³ will.
pass down through the ports m' and o, and move the piston B to the point where
it is desired to cut off the steam. This cut off is effected by means of the valve O
closing the port m¹ which operation also moves the valve O¹, as both valves are
connected to the same stem o. When the valve O¹ is at the point of opening the
port n the valve O is at the point of closing the port m¹, and as the engine
continues its stroke under the pressure of the steam, the valves O and O¹ move so
that the-former keeps the port m³ closed and the latter keeps the port n' open,
admitting, the steam from the receiver M, (which is filled by exhaust steam from
the previous stroke,) into the low pressure cylinder against the piston B'. The
exhaust from the low pressure cylinder passes through the port P to a condenser.
By employing the compensating cross head described in the said specification
the space behind the piston in the low pressure cylinder may be regulated, so that
if the pressure on the high pressure piston is small, the space behind the piston in
the low pressure cylinder may be made correspondingly small.
By these means I obtain the full amount of pressure of the steam, securing the
saine result from this engine, with half the steam necessary with other engines
in which the steam is not admitted until the stroke is completed.
I would have it understood that I do not limit the application of my invention
to a direct acting engine, as it may be employed with engines of different con-
structions such as crank engines, simple engines, duplex. engines & and engines
in which the valves of one engine are operated by the other engine, nor do I limit
myself to the exact parts shown and described, as many slight changes might be
made therein without departing from the nature of my invention.
Having now particularly described and ascertained the nature of the said
invention 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
First. The combination with a high pressure cylinder and a low pressure
cylinder, of a receiver, into which the steam from the high pressure cylinder
exhausts and which communicates with the steam chest of the low pressure cylinder;
and valves for simultaneously cutting off the steam from the high pressure cylinder
at a certain, portion of the "stroke, and allowing the steam in the said receiver to
expand against the piston in the low, pressure cylinder, substantially as set forth.
Second. The combination with a high pressure cylinder and a low pressure
cylinder of the receiver M, the pipe M¹ connecting the said receiver with the steam
chest M³ of the low pressure cylinder the slide valves N N¹ and the cut-off
valves O, O¹, all substantially as, and for the purpose, set forth.
HASELTINE, LAKE & Co.,
For the Applicant,