An Improvement in Single Acting Compound Steam Engines.
Year: 1897

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 18 of the Patents, &c. Act 1883) as allowed by
the decision of the Chief Examiner of the 22nd day of July 1898.
PROVISIONAL SPECIFICATION.
An Improvement in Single Acting Compound Steam Engines.
We, WILLIAM HOPE WILSON, Engineer, and ROBERT BRYSON MITCHELL, Secretary
of The Mirrlees, Watson & Yaryan Company Limited, both of 45, Scotland Street,
Glasgow, do hereby declare the nature of this invention to be as follows:-
-
This invention relates to a construction of single acting compound engine
specially adapted for rapid working. A high pressure and a low pressure cylinder
are arranged parallel to one another, their pistons being connected to cranks set
opposite to one another, and a space between the cylinders, constituting a valve
chest, is occupied by two slide valves fixed on one rod worked by an excentric
or otherwise. Each of the slide valves is made with two end pistons having
cylindrical part of less diameter between the pistons, and both are hollow, giving
passage for steam through them.
a
The upper valve, when it ascends, opens communication from an annular
chamber supplied with boiler steam to a port leading into the top of the high
pressure cylinder, and as it descends it first closes that port and then opens it so
as to allow exhaust steam to pass over the top of the valve and down through it
to a reservoir chamber below. The lower slide valve, when it descends, opens
communication from this reservoir chamber to a port leading to the upper end of
the low pressure cylinder which is thus supplied with steam from the exhaust of
the high pressure cylinder, and as this valve ascends, it first closes that port then
opens it to an annular exhaust chamber, from which the final exhaust steam is led
off. A port at the bottom of the high pressure cylinder and a port a little above it
both lead into a chamber below the lower valve, this chamber forming part of the
reservoir chamber as the two parts communicate through the lower valve. Thus
as the high pressure piston ascends the space below it receives steam from the
reservoir, sending it back to the reservoir as it descends thereby increasing the
pressure of the steam which supplies the low pressure cylinder.
The lower of the two ports also allows escape of water from the high pressure
cylinder, and the upper of the two ports, which is above the piston, when it is at
the lower end of its stroke, makes communication between the reservoir chamber
and the high pressure cylinder above the piston which then ascends with equal
pressures above and below.
The low pressure cylinder has also at its bottom a port opening to the exhaust
chamber, so that as the low pressure piston ascends it has equal pressures above
and below it.
The lower piston end of the upper valve always prevents communication between

page_text: the steam supply chamber and the reservoir, and the lower piston end of the lower
valve in like manner prevents communication between the reservoir and the
chamber for final exhaust.
ABEL & IMRAY,
Arents for the Applicants.
We, WILLIAM HOPE WILSON, Engineer, and ROBERT BRYSON MITCHELL, Secretary
of the Mirrlees, Watson & Yaryan Company Limited, both of 45, Scotland Street,
Glasgow, 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 a construction of single acting compound engine
specially adapted for rapid working as we shall describe referring to the accom-
panying drawing which is a vertical section of the two cylinders of the engine
and the intermediate valve chest.
The high pressure cylinder H and the low pressure cylinder L are fixed parallel
to each other their pistons, being connected in the usual way to cranks opposite to
one another on a crank shaft.
The valve chest C situated between the cylinders is occupied by two piston valves
each having two packed parts h¹ and h² for the high pressure valve and ¹² for
the low pressure valve.
Between the parts h¹² and 12 there are parts h and 7 respectively of smaller
diameter affording annular passages around the valves. Both valves are hollow
throughout and are fixed on one rod R worked by an eccentric on the crank
shaft. In the valve chest there is an annular cavity S to which steam is led from
the boiler, and another cavity E from which the exhaust steam is discharged.
The cylinder H has on the one end a port 1" and at the other end a port P2.
The cylinder L has at one end a port Q leading to about the middle of the valve
chest and its other end is open to the exhaust cavity E which communicates with
the annular space in the valve chest by a port Q³.
When the valve ascends so as to put Pi in communication with S then steam
enters the cylinder H above its piston and propels its piston downwards the steam
from below the piston of H passing by P2 into the valve chest and interior of
the valve as a reservoir the pressure in which is thus increased becoming available
in the low pressure cylinder.
At the same time being put in communication with Q the steam passes from
the upper end of the cylinder L to the exhaust E, the piston of L ascending with
equal pressure on both its sides. When the valve descends the port P¹ is put in
communication with the upper part of the valve chest and the interior of the
valve and at the same time the port Q is put in communication with the space
between the two valves, so that as the piston of H ascends, steam passes from
above it through the valve to the port Q and into the cylinder L propelling its
piston downwards. At the same time steam from the interior of the valve passes
by the port P2 into the cylinder H below its piston which thus has equal
pressures on both its sides, and the steam below the piston of L passes to the
exhaust.
Obviously the described construction and arrangement of cylinders and valves
are applicable in an engine worked by elastic fluid other than steam.

page_text: Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that we are aware that
for compound engines two parallel cylinders have been arranged side by side with
piston slide valves between them, we therefor make no general claim to such an
arrangement but what we claim is:-
A single acting compound engine having two parallel cylinders the pistons of
which are connected to opposite cranks, on one shaft and having between the
cylinders a valve chest fitted with two hollow piston valves both on one rod worked
by an eccentric on the crank shaft so as to govern ports of the cylinders leading to
and from an intermediate steam reservoir the valves, ports and reservoir being so
arranged that the lower parts of the two cylinders under their pistons are never in
communication with each other substantially as described with reference to the
drawing.