Year: 1887

page_text: I PARDON ARMINGTON of 12 Franklin Street Providence Rhode Island one of the
United States of America Manufacturer of Steam Engines 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 relates to piston valves for steam engines especially of that class
wherein a high speed is desired, and has for one of its objects to construct the valve
cylinder so as to provide an increased bearing surface for the piston valve.
The valve cylinder referred to is provided with port openings extended about it and
which communicate with the main cylinder, the said port openings registering with
a main and auxiliary port in the piston valve, thereby admitting the maximum
quantity of steam to the engine cylinder with a maximum travel of the piston valve,
the waste room in the said piston valve being reduced to a minimum.
Prior to my invention I am aware that a piston valve has been constructed of a
single casting closed at its ends and provided with steam ports at its centre and ends,
the said valve having a bearing surface substantially its entire length.
My invention therefore consists essentially in a steam engine, of the engine cylinder,
an independent valve cylinder provided with port openings communicating with the
engine cylinder, combined with a piston valve for the said valve cylinder having a
bearing surface of substantially the length of the said cylinder and provided with
openings to register with the port openings in the said valve cylinder, substantially as
will be described.
Other features of my invention will be pointed out in the claim at the end of this
specification.
Figure 1 is a longitudinal section of a portion of a steam engine provided with my
improved piston valve.
Figure 2 a transverse section of Figure 1 on the line x-x.
Figure 3 a section of one of the piston valves on line y-y of Figure 1 and
Figure 4 a modification to be referred to.
The engine cylinder A, as herein shown, has cast integral with it two independent
valve cylinders a, a', which co-operate to form a single piston valve cylinder.
Each cylinder a, a', receives within it an independent piston valve a³, a³, respectively,
Price 8d l

page_text: which are joined together to form a single piston valve by a valve stem a* connected
to any suitable or well known valve gearing to operate the said piston valves in
unison.
Each piston valve is closed at one end and open at its other end to receive live
steam.
Each cylinder a, a¹, near one end is provided with an annular channel b which forms
in the respective cylinders the main port opening of cylinder ports 1, 62, and near its
opposite end each cylinder has an annular channel of smaller area in cross section
than the channel b, the channel b forming an auxiliary port opening to the cylinder
ports and being connected with the main port 6 near the top of the respective cylinders
by the passage 6 and with the cylinder ports below the bottom of the said cylinder
by the passage bº.
b
Each piston a, a, is made hollow and has on its inner side, as herein shown, longi-
tudinal ribs and each piston also has annular openings or grooves c², c², to register
with the port openings b, b, respectively.
C,
It will be noticed that the interior surface of each cylinder a, a', constitutes the seat
for its piston valve, and that the said piston valve is substantially equal in length to
the length of the said cylinder on its inner surface, consequently obtaining for the said
piston valve a bearing substantially its entire length.
The piston valve having a bearing surface substantially equal to its length and being
balanced may be run very quickly and smoothly.
Referring to Figures 1 and 4, it will be seen that steam is about to be admitted to
the engine cylinder through the main port b' and the auxiliary port 63 communicating
therewith, of the piston valve a².
The auxiliary port opening c² is of such area in cross section as compared with the
main port opening c¹ of the piston valve, that when the auxiliary port opening c² is
fully opened, the said opening 2 plus the amount to which the main port opening c¹
has been opened equals substantially the total area in cross section of the main port
opening thereby admitting the maximum amount of steam to the engine cylinder with
the minimum travel of the piston valve.
In figure 11 have shown the cylinders a, a¹, as connected at their ends with the
exhaust ports d, d', the steam in the engine cylinder being quickly exhausted
therefrom, but instead of having an exhaust port located at the end of each cylinder
a common exhaust for both the ports 2, 62, may be located between the two
cylinders a, a, and in this case the position of the piston valves will be reversed,
as shown in Figure 4, as will also the arrangement of the main and auxiliary
ports, the said piston valves taking steam at the outer ends of their respective
cylinders.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a steam engine, the engine cylinder, an independent valve cylinder provided
with port openings 6, 63, connected together, and communicating with the engine
cylinder, combined with a piston valve for said cylinder having a bearing surface of
substantially the length of the said cylinder and provided with port openings to
register with the port openings in the said valve cylinder, substantially as and for the
purpose specified.
2. In a steam engine, the engine cylinder, an independent valve cylinder provided
with port openings 6, 63, connected together and communicating with each end of the
engine cylinder, combined with a piston valve for each cylinder having a bearing
surface of substantially the length of the said cylinder and provided with openings to
register with the port openings in the said valve cylinder, and with a valve stem to
connect both piston valves, substantially as described.
3. In a steam engine, the engine cylinder, and independent valve cylinders
provided with port openings 6, 63, connected together and communicating with each
end of the engine cylinder, combined with a piston valve for each cylinder having a

page_text: bearing surface of substantially the length of the said cylinder and provided with
port openings to register with the port openings in said valve cylinder, the said piston
valve having one end open to receive steam between said valve cylinders, and closed
near the exhaust, and with a valve stem to connect both piston valves, substantially as
described.
4. In a steam engine, the engine cylinder and independent valve cylinders provided
with port openings 6, 63, connected together and communicating with each end of the
engine cylinder, combined with a piston valve for each cylinder having a bearing
surface of substantially the length of the said valve cylinder and provided with
strengthening ribs on its inner side, and with port openings to register with the port
openings in the said valve cylinder, the said piston valves being connected by a single
valve stem, substantially as and for the purpose specified.
Dated the 27th day of September 1887.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London,
Agents for the Applicant.