Improvements in Steam Engines.
Year: 1895

page_text: Date of Application, 10th Oct., 1895
Complete Specification Left, 10th July, 1896-Accepted, 5th Sept., 1895
Improvements in Steam Engines.
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 is applicable to non-condensing compound engines and the object
of the invention is to reduce the consumption of steam and to improve the working
of the engine at light loads by preventing the formation of a partial vacuum in
the low pressure cylinder, owing to the steam expanding below atinospheric
pressure. For this purpose I provide between each end of the cylinder and the
exhaust pipe a self-acting non-return valve the arrangement being such that in the
event of the pressure falling slightly below the atmosphere the valves will open
and exhaust steam will be drawn in.
In the case of a steam engine in which the steam nets on one side only of the
piston, the piston ring itself can be arranged to net as the valve for instance as
follows:-
The internal diameter of the piston ring is made sufficiently large to leave an
adequate annular space between its inner circumference and the outer circumference
of the piston body and the ring is free to move parallel with the axis of the
piston but to an extent limited by spring fingers projecting from a spring ring
that is let into the piston body.
Or the groove in the pistou maly my be made deeper than the ring, with
ventilating holes from the groove to the steam side of the piston.
Dated this 9th day of Octuber 1805
Improvements in Steam Engines.
1, JOHN SMITH RAWORTH, formerly of 24 Kirkstall Road, Streatham, but
now of 46 Christchurch Road, Streatham 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 is applicable to non-condensing compound engines and the object
of the invention is to reduce the consumption of steam and to improve the working
of the engine at light loads by preventing or arresting the formation of a partial
vacuum in the low pressure cylinder such as is liable to occur owing to the steam
expanding below atmospheric pressure. For this purpose in the case of a steam
engine in which the steam acts on one side only of the piston (the other side of
the piston being open to the exhaust) the piston ring is arranged to act as a valve
the arrangement being such that in the event of the pressure falling slightly below

page_text: that of the atmosphere, the piston ring will lift and permit exhaust steam to be
drawn into the cylinder space on the steam si le of the piston.
Fig. 1 of the accompanying drawings is a part sectional view of a low pressure
cylinder with piston 2 fitted with a ring 3 adapted to lift and act as a valve for
the purpose mentioned.
The internal diameter of the piston ring is male sufficiently large is shown, to
leave an adequate annular space 4 between its inner circumference and the outer
circumference of the piston body, and the ring is free to move parallel with the
axis of the piston but to an extent limited by spring fingers 5 projecting from a
spring ring 5 let into the piston body, so as to then provide a steam way between
the adjacent annular surfaces of the piston ring and piston and the annular space 4
for the passage of exhaust steam from the lower or outer side of the piston to the
upper or inner side thereof.
Fig. 2 is a similar view to Fig. 1 showing a lightly molifiel arrangemest in
which the groove in the piston body is mede deeper the the ring 3, and ventilating
holes 6 lead from the groove to the ten side of the piston.
Fig 3 shows a valve 3 of which there may be several) normally kept closed
against a seat in the piston boly by a spring 7 in oppsition to which the valves
will be opened when the pressure at its steam sile falls below that at the reverse
side.
Having now particularly described and ascertained the nature of the said inven
tion and in what manner the same is to be performed I declare that what |
claim is :-
1. In steam engines such as hereinabove referred to the method caletantially as
described or preventing of testing the formation of a partial va in the lar
pressure cylinder by admitting exhaust steam the reto by a valve or valves in an
automatic manner as set forth.
2. In steam engines of the kind herein referred to, low pressure pistons and
packing rings constructed to act as valves for the purpose specified the arrangement
and operation being substantially hereinbefore described with reference
respectively to and shown in Fig. and in Fig. 2 of the drawi ggs annexed.
Datel this 10th day of July 1896.
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Charterel Patent Agent.