Year: 1888

page_text: I, ARTHUR GEORGE BROWN of the Globe Iron Works, Bolton, Lancashire, Engineer,
do horeby declare the nature of my said 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 improvements in Compound Engines of the single-acting
type and consists essentially of a small or high pressure and a large or low pressure
cylinder placed side by side and inverted over a pair of cranks set 180° apart upon a
crank shaft passing through an enclosed chamber or casing with a valve chest and
distributing valve arranged vertically between the two cylinders-the whole constituting
a simple and compact Compound Engine.
On the accompanying drawings I illustrate four sectional views of my improved
compound engine Fig. I being a front sectional view and Figs. 2. 3. and 4 being side
sectional views shewing the interior arrangements from which the construction of the
engine may be readily understood.
In all the views a is the high pressure cylinder b the low pressure cylinder and c
the valve chest all mounted upon the top of the enclosed chamber or casing & herein-
after called the crank-chamber.
The cylinder and valve chest are in the larger sizes of engine cast in one piece and
bolted to the top of the crank chamber but in the smaller sizes the crank chamber and
cylinder are cast together.
The cylinder heads a² and b¹ cover the upper ends of the cylinder only, the lower
These cylinder heads
ends opening directly into the crank chamber as illustrated.
are each provided with a spring relief valve e to allow of the escape of water of con-
densation carried into the cylinder in starting or arising from priming in the boilers
and so by setting these valves to lift at a few pounds more than the steam pressure
and thus allowing the water to escape freely I prevent damage to the engine from this
cause.
The pistons a' and 6* are of the trunk form and are connected direct to their respec-
tive cranks g and g' upon the crank shaft by their connecting rods a³ and 63. This
shaft is supported in bearings on the removable heads d' of the crank-chamber and in
the large engines also in a central bearing aª. This arrangement of the bearings

page_text: permits of either of the end bearings of the shaft f being readily removed for inspection
without disturbing the shaft itself or the crank-chamber heads. Side covers h are
also provided to the crank-chamber to facilitate access to the interior.
The crank-chamber d is constructed to hold a body of water and oil and the cranks,
connecting-rods, eccentric and governor pass through this oil at each revolution giving
a constant and thorough lubrication to all the working parts-a stream of oil and water
also passes constantly over the main bearings.
i is a cup formed on the top side of the main bearing inside the crank-chamber and
designed to catch a portion of the oil and water splashed up by the working parts of
the engine and so conveying the same down the channel j on to the main bearing and
which passing along the bearing surface finally reaches the outer end thereof where
coming in contact with a ring & (spring upon the shaft) it is thereby thrown outwards
by contrifugal action and being so caught in the annular chamber is led back through
the channel m into the crank-chamber. An overflow n is provided for the escape of
the excess of water and so the level in the crank-case is maintained at the desired
height.
The ports o leading from the valve chest to the high and low pressure cylinder are
arranged with their top surfaces at or slightly above the same level as the under side
of the cylinder covers in each caso-so as to obtain perfectly straight direct and short
passages between the two.
The action of my improved compound engine may be described as follows:-
Steam enters from the boiler through the side passage 1 and passes through port 2
into the annular space 3 (surrounding the neck of the valve) and between the two valve
pistons 4 and 5 and passes through the port 6 into the high pressure cylinder pressing
the piston a down and turning the crank and its connections.
As the piston moves down the valve is "timed" to cut off this admission of steam
and the remaining portion of the stroke is then made with expanding steam. Jost
before the piston a reaches the bottom of its stroke the valve opens a communication
through the ports 7 between the high and low pressure cylinders-this being the
position of the valve as illustrated in Fig. 4.and as the cranks are set opposite the low
pressure piston 63 is then at the top of its stroke and is immediately pressed downwards
by the steam discharged from the high pressure cylinder. As the piston 6 moves
downwards the high pressure piston a is moving up towards the top of its stroke
displacing the steam in its cylinder and which passes over to the low pressure side.
When the stroke is partially completed the valve closes the communication between
the two cylinders and the remaining stoam in the high pressure cylinder is com-
pressed so resisting the upward movement of the piston and bringing it gradually
to rest at the top of its stroke ready to commence the next downward stroke. Mean-
while the low pressure piston completes its downward stroke with expanding steam
and just before reaching the bottom the valve opens a communication through the
passages 7 and 8 with the open atmosphero in the case of a non-condensing engine. If
howover the engine is worked with a condenser the passage 8 is connected to such
condenser and a vacuum is immediately formed in the cylinder to start the piston on
its upward stroke thus relieving the crank pin of the work of lifting it.
If now no means were provided for counteracting the effect of the vacuum pulling
the piston upwards the connecting rod would be lifted away from the crank pin and a
hard knock cach stroke would result-to avoid this the low pressure piston is formed
with a trunk of considerably smaller diameter than the piston head itself leaving an
annular space p between this trunk and the walls of the cylinder-in which annular
space air or vapour is alternately compressed and expanded forming a vacuum at the
upper end of the stroke to prevent the vacuum above lifting the piston and its connec-
tions and serving by being compressed at the other end of the stroke to cushion the
downward momentum of the piston.
The water and excess of air or vapour in this annular space pass out through the
spring valvo into the crank chamber and which valve, prevents the return of such
vapour or air or the same may be led away through pipes if desired. The valve r may
be placed as shewn or in any other convenient position..

page_text: I have in the drawings shewn the eccentric s fitted with my improved governor but
as this forms the subject of another application for Letters Patent I have not described
it herein.
Having thus particularly described and ascertained the nature of this my said
invention and in what manner the same is to be performed I declare that what I
claim is :-
:-
1st. The combination and arrangement of parts constituting an improved Compound
Engine substantially as herein before described and illustrated.
2nd. In a Compound Engine the employment of a single piston valve working in a
valve chest pinced vertically between the high and low pressure cylinders and provided
with an annular space separating the valve into two pistons the valve cylinder being
provided with suitable ports for controlling the requisite communication between the
two cylinders substantially as hereinbefore described and illustrated.
3rd. Constructing the low pressure cylinder with an annular space surrounding the
trunk of its piston and provided with an outlet valve substantially as and for the
purposes hereinbefore described and illustrated.
4th. The employment of a cup formed upon the top of the main bearings in conjunc-
tion with passages communicating with an annular chamber substantially as and for the
purposes hereinbefore described and illustrated.
Dated mis om day of December 1000.
JOHN G. WILSON,
Patent Office, 55, Market Street, Manchester,
Agent for the Applicant.