Improvements in Steam Engines.
Year: 1892

page_text: Date of Application, 4th Jan., 1892
Complete Specification Left, 3rd Oct., 1892-Accepted, 17th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Steam Engines.
I, HENRY JAMES COLES of 89 Sumner Street Southwark in the County of
London Mechanical Engineer, do hereby declare the nature of this invention to be
as follows:
My invention relates to that class of steam engine generally known as high speed
single acting engines and is especially adapted for compound engines in which there
are two pairs of cylinders. It consists in making the low pressure pistons annular the
high pressure cylinders being formed in the low pressure pistons the high pressure
pistons are fixed to the top cylinder covers and the steam and exhaust ports and
passages are so arranged that the admission and eduction of steam can be regulated
by a single valve placed preferably between the two pairs of cylinders the steam
passing from the high pressure cylinder of one pair of cylinders into the low
pressure cylinder of the other pair of cylinders.
Some of the ports are made in the pistons to shorten the passages.
A modification of this arrangement can be adapted to triple expansion engines.
Dated this 4th day of January 1892.
HENRY JAMES COLES.
COMPLETE SPECIFICATION.
Improvements in Steam Engines.
I HENRY JAMES COLES Mechanical Engineer of Sumner Street Southwark
in the County of London do hereby declare the nature of my invention for
IMPROVEMENTS IN STEAM ENGINES and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
My invention relates to that class of engine generally known as high speed single
acting engines and is especially adapted for compound engines in which the
cylinders are in double pairs.
In an engine of the above mentioned type I make the low pressure pistons in the
form of trunks having the high pressure cylinders formed in the centre thus
making the low pressure pistons annular in form. The high pressure pistons are
also in the form of trunks and are attached to the cylinder cover and have no
motion whatever.
Between the double pairs of cylinders a single valve is fitted and arranged to
work both pairs of cylinders. This valve is by preference cylindrical in form and
is also hollow to allow some of the exhaust steam to pass down the centre.
The steam on entering the engine is allowed by the valve to pass at the proper
time into the high pressure cylinder say that on the right hand side of the engine
through a port made through the side of the low pressure piston.
When the steam has done its work in that high pressure cylinder it is at the
proper time exhausted into the low pressuré cylinder on the opposite side that is on
the left hand side of the engine and when it has done its work in that cylinder it is
exhausted into the air or otherwise through two separate sets of passages in order
that the piston may be readily relieved of any pressure due to the steam.
One of these sets of passages which I call the auxiliary exhaust consists of a
series of holes made in a projecting ring forming part of the walls of the high
pressure cylinder. These holes come opposite a corresponding set of holes when

page_text: the piston is at the bottom of the stroke which are made in the trunk of the high
pressure piston which is hollow and allows a portion of the steam to escape into
passages made in the cylinder cover and thence through the centre of the steam
valve into the exhaust pipe, the egress through this set of passages is very soon
closed as the piston ascends on its return stroke.
The other set of exhaust passages are made to communicate with the valve box
and the exhaust is regulated by the valve in the manner usual in ordinary steam
engines.
The low pressure piston has as above mentioned a port in its side through which
the steam passes to the high pressure cylinder and to maintain the supply through
the proper proportion of the stroke and also to allow the proper escape of the
exhaust, an elongated passage is made in the side of the low pressure piston, but
in order that the area of this passage which is subjected to steam pressure should
not destroy the balance of the low pressure piston a recess of equal area is made
in the opposite side of this piston communicating with the interior of the high
pressure cylinder by means of a hole or passage and thus equalising the pressure
on either side of the low pressure piston.
The power is communicated from the pistons to the crank shaft by means of
connecting rods and the valve is actuated by means of an eccentric & valve rod or
other suitable mechanism.
In the drawing herewith
Fig. 1 is a sectional view of the engine shewing the two pairs of cylinders the
left hand pair being in section shewing the interior of both high and low pressure
pistons, the right hand engine only shews the outside of the low pressure piston.
Fig. 2 is a section through the line X Y showing one of the annular low
pressure pistons with the high pressure cylinder in the centre also the passage for
the steam into the high pressure cylinder and the equilibrium recess on the opposite
side.
S is the steam inlet shown by a dotted circle, V is the steam valve for all four
cylinders, P is the steam passage from valve chest for high pressure steam, p plare
the passages through the low pressure piston into the high pressure cylinder, D is
one low pressure cylinder, C is one high pressure cylinder, A is one high pressure
piston, B B one low pressure piston, F is the port for steam admission and emission
to and from the low pressure cylinder D, M is the low pressure steam and exhaust
port from the left hand high pressure steam cylinder into the right hand low
pressure cylinder K K are the auxiliary exhaust ports, G G are the passages in
the cylinder cover for the auxiliary exhaust, R is the equilibrium recess in the low
pressure piston to balance the passage p.
The course of the steam is from the inlet S through P p & p' into the left hand
high pressure cylinder C, when it has done its work in that cylinder through p¹p & P
into the valve chest & thence by the port M into the right hand low pressure
cylinder, after it has performed its work in this cylinder part of it passes through
auxiliary exhaust ports similar to K K and through the passage & through the
centre of the valve V and out at E, the remainder passes through the passage M
and into the cylinder cover through N N when it follows the same course as the
auxiliary exhaust steam does. The course of the steam working in the right hand
high pressure cylinder & the left hand low pressure cylinder is similar to that above
described but opposite in direction as regards the cylinders.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
1st. In a compound engine using a pair of annular pistons each containing a
: central cylinder working on a fixed trunk piston in such a manner that the central
cylinder in either annular piston exhausts to the face of the annular piston on the
opposite side of the engine.
2nd. In a compound engine constructed and working as herein described, making

page_text: the high pressure steam passages through the low pressure pistons substantially
as berein shewn & described.
3rd. In a compound engine as herein described, making the equilibrium recess
in the side of the low pressure piston and a passage leading thereto from the
high pressure cylinder substantially in the manner & for the purposes herein
described.
4th. Making the auxiliary exhaust ports and passages in the high pressure trunk
pistons substantially as herein shown & described.
5th. Making the cylinder cover for both cylinders with the auxiliary exhaust
passages formed therein substantially as herein shewn & described.
2nd day of October 1892.
HENRY JAMES COLES.