Year: 1895

page_text: Date of Application, 1st Mar., 1895
Complete Specification Left, 2nd Dec., 1895-Accepted, 15th Feb., 1896
I, JOHN SMITH RAWORTH, of 24 Kirkstall Road, Streatham, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention has reference to improvements in steam engines and is particularly
applicable to tandem compound or triple expansion engines.
According thereto the cylinders are placed one above the other, or one in front
of the other, according as the engine is vertical or horizontal, and the valves are
placed between the adjacent cylinders, that is to say in compound engines the
valves would be placed between the high pressure and low pressure cylinders and
in the case of a triple expansion engine they would be placed between the adjacent
ends of the several cylinders. By this means the clearances in the ports and
passages are reduced to a minimum. I profer to use valves of the well known
Corliss type, but similar results may be obtained with more or less efficiency with
other forms of valves.
Compound engines constructed in accordance with my invention are double
acting as regards the forces transmitted by the piston rod, but are single acting in
each cylinder, that is to auy the high pressure steam acts upon the under side of
the high-pressure piston and the expanded steam acts upon the upper side of the
low-pressure piston in a vertical engine, and upon the corresponding sides in a
horizontal engine.
I, JOHN SMITH RAWORTH, formerly of 24 Kirkstall. Road, Streatham, but now
of 46 Christchurch Road, Tulse Hill, in the County of Surrey, Engineer, 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:-
"
My invention has reference to improvements in steam engines in which two or
more cylinders are used in tandem.
According thereto the cylinders are placed one above the other, or one in front
of the other according as the engine is vertical or horizontal-and valves of the
well known Corliss type are placed between the adjacent ends of the cylinders,
that is to say, in compound engines the valves would be placed between the high
pressure and low pressure cylinders, and in the case of a triple expansion engine
they would be placed between the adjacent ends of the several cylinders. By this
means the clearances in the ports and passages are reduced to a minimum.

page_text: Compound engines constructed in accordance with my invention are double
acting as regards the forces transmitted by the piston rod, but are single acting in
each cylinder, that is to say the high. pressure steam acts upon the under side of the
high pressure piston and the expanded steam acts upon the upper side of the low
pressure piston in a vertical engine, and upon. the corresponding sides in a
horizontal engine.
In the accompanying drawings,
Fig. 1 shows partly in vertical section on line A B of Fig. 2, and partly in
elevation, a compound vertical steam engine embodying this invention.
Fig. 2 shows the engine in elevation, and Fig. 3 is a sectional view at right
angles to Fig. 1.
Figs. 4 and 5 are sections through the valve box on. the lines. CD and E F
respectively of Fig. 3.
The high pressure steam enters through the end of the valve chamber d between
the end of the two cylinders and is admitted at suitable intervals through the
ported to the high pressure cylinder a by a valve g which is of cylindrical form
and vibrates about its axis. When the high pressure piston arrives at the top of
its stroke, it passes a ring of port holes as by means of which, equilibrium is
established between the steam pressures in the cylinder a and the receiver / which
is in communication by means of the ports with the pockets * * in the valve
box. The cylinder a is surrounded by a live steam jacket a¹.
The high pressure piston having now arrived, as described, at the top of its
stroke, and the high pressure steam port having been previously closed, the low
pressure valve h, which is also of cylindrical form and vibrates about its axis, will
liave commenced to open a passage between the high pressure oylinder a and the
low pressure cylinder b and this passage will remain open until the point of cut off
is reached, say one half to three quarters of the stroke, when the passage e to the
low pressure cylinder will be closed and. the steam remaining in the high pressure
oylinder will pass through the ports (Figs. 4 and 5). into the receiver i.
The low pressure piston n on arriving at the bottom of its stroke passes a ring
of port holes which allow the water and steam to pass out into the exhaust
chamber from which an outlet is provided at i².
On the up or return stroke of the low pressure piston a, an outlet for the steam
remaining above the piston is provided through the pipe i by the exhaust cavity of
the valve euclosing the two ports e² ².
The valves d and h are driven by levers, fixed to the ends of their spindles, from
eccentrics and rods as shown in the drawings, or by any other well known method
suitable for the size and speed of the engine.
The method of governing shown in Figs. 2 and 3 is by means of a centrifugal
governor carried by the crank shaft and arranged to vary the throw of the
eccentric, but an ordinary throttle valve acting upon the steam inlet may be used
if required.
During the down stroke of the high pressure piston steam from the receiver / obtains
access to the top side of the piston-m. In non-condensing engines this communica
tion may be constant. through holes in the cover a, but in condensing engines, it is
better. to make it.intermittent through the port holes as as shown.
The steam jacketa' is supplied with live steam through a small'port a communica-
ting with the valve chamber d, and the condensed water is collected at each stroke in
a small pocket,in the low pressure valve-fed, by a.similar port and by the motion of
the valve carried round and discharged through a small port. leading into the
exhaust cavity. These ports, and the corresponding pocket in the valve; are
merely drilled boles. and. are too small to be, visible: iu.the drawings. A relief
valve it is placed in.the head of the low pressure. oylinder to discharge water or
expessive steam pressure. to the receivan l..
The cylinders are carried on.a. hollow truncated: cone: framant which, for small
engines, may be castiin, one piece,.bas for large engines may be built up in any
convenient, and. suitable; mappen. This frame, which is provided, with large