Improvements in and relating to Steam or other Fluid Engines or Pumps.
Year: 1890

page_text: Date of Application, 13th Oct., 1890-Accepted, 15th Nov., 1890
COMPLETE SPECIFICATION.
Improvements in and relating to Steam or other Fluid Engines
or Pumps.
WO ARTHUR GEORGE MUMFORD of the Culver Street Iron Works, Colchester, in the
County of Essex, Engineer and ALFRED ANTHONY, Draughtsman, at the aforesaid
Works, 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:-
Our invention relates to an improvement in that class of engines or pumps
having duplex cylinders the pistons of which act as distributing valves to the said
cylinders, and it consists in the use of supplemental ports adapted to enable one of
the pistons to start, should they both be at a state of rest at, or about, the centre
of the length of the cylinders, due to the positions of the steam and exhaust ports
to give the required lap necessary to make each piston pause at each end of its
stroke, the object being to better adapt this class of engine to the duty of a direct-
acting pumping engine to work against heavy pressure.
As is well known, it is desirable that the plunger of a pump to work against heavy
pressure should make a distinct pause at each end of its stroke, that is, it should
remain at rest a period more or less prolonged before reversing its motion. To ensure
this action in engines of the duplex cylinder type herein before referred to, when working
pumps direct, it is essential that there should be a certain amount of lap on the parts
of the piston which give steam to the other cylinder, that is to say, that each piston
should travel a certain distance about the middle of the length of its cylinder without
admitting steam to, or exhausting from, either end of the other cylinder, so as not
to reverse the motion of the other piston too quickly. The result of this is that
it is possible for both pistons to get in such a position at, or about, the centre of
the lengths of the cylinders, that neither can give steam to, or exhaust from, either
end of the other cylinder, and consequently the pump cannot start. To overcome
this difficulty we form supplemental ports between the bores of the cylinders, and
we form supplemental ports in the pistons, so that should both pistons be at a state
of rest at, or about, the centre of the lengths of the cylinders, thero is a communication
through the said supplemental ports from the steam chest to the ono end of one
piston, and from the other end of the said piston to the exhaust, in the manner
illustrated in the accompanying drawings in which
Figure 1, Sheet No. 1, is a view in sectional side elevation through one of the
cylinders.
Figure 2, Sheet No. 1, is a view in sectional plan through the centre of the
cylinders.
Figure 3 Sheet No. 2, is a view in transverse section through the central ports of
the cylinders and through the end ports at the back of each piston, the pistons being
both at the front, or stuffing box, end of the cylinders.
Figure 4, Sheet No. 2, is a transverse section through the central ports in the
cylinders and through the central ports in both pistons, the pistons being both in the
middle of their stroke, and
Figures 5 and 6, Sheet No. 2, are views of both pistons turned over, showing their
end and central ports.
Throughout these views similar parts are marked with like letters of roference.
Referring to the several figures of the drawings, A and A' designates the cylinders.
B and B' designate the pistons fitted with piston rods B', B. C desiguates the steam
chamber common to both cylinders A and A', from which the steam is admitted into
the annular spaces round the pistons and from thence into the steam ports by means
of the holes c and c' in the cylinders. D designates the exhaust chamber common
D
017

page_text: to both cylinders and in communication therewith by the ports d and d¹. A³ and A³
designate the guides or studs which engage with recesses B³, B³, in the pistons
to prevent their rotation. E, E and E', E¹ designate the steam slots or ports
in the pistons B and B respectively, and F, F¹ designato the exhaust ports in the
pistons B and B' respectively. e, c and el, el designate the ports in the two cylinders A
and A¹ respectively, and e³, e, etc. the passages connecting the said ports for the
induction and eduction of tho steam, and d and d designate the ports or passages
between the exhaust ports F and F and tho exhaust chamber D. G,G,G and G¹, G¹,G¹
designate the balancing recesses in the pistons B and B respectively. So far the
construction of the engine presents no novel features, the construction and action
being well-understood,and we will now proceed to describe our invention. At the middle
of the length of each cylinder are formed two supplemental ports H and H'connecting
the bores of the two cylinders A and A' together. These supplemental ports are
preferably formed one above the other, and below the centre line of the cylinders.
At the middle of the length of the piston B are two supplemental ports 6 and b¹
coinciding when the piston is at or about the centre of the length of its stroke-
with the supplemental ports H and H' and putting them respectively into communi-
cation with the steam and exhaust of its cylinder, the former through the balancing
recess G, and the latter direct into the exhaust passage d.
At the middle of the length of the piston B are two supplemental ports 62 and 63
coinciding when the piston is at or about the centre of its stroke-with the supple-
mental ports H and H¹ and putting them in communication with the two steam
ports e', e¹ of its cylinder, the port H with the outer port e and the port H' with the
inner port e'. The lengths of these supplemental steam ports are so proportioned that
they begin to open to one another at the same moment that each piston respectively
closes the end ports of its cylinder on the one side,and remains open till the piston has
opened the end ports of its cylinder on the other side.
The action of the supplemental ports is as follows;-When both pistons are in such
a position that neither can give steam to the other by the end ports, communication
is oponed through all the supplemental ports in both cylinders and pistons as shown
in Figure 4, Sheet No. 2 of the accompanying drawings. Steam then passes by the
port 6, in the piston B, through the port H and thence by the 6 in the piston B¹ to
the outer steam port e' in the cylinder A¹ and thence to the back of the piston B.
At the same time the exhaust steam from the other end of the piston B passes by
the central port 6 in the piston B' through the port H', thence by the central port 61
in the piston B. and the exhaust port d to the exhaust chamber D as shown by the
arrows in Figure 2, Sheet No. 1 and Figure 4 Sheet No. 2 of the accompanying
drawings. This causes the piston B to make a stroke towards the forward, that is,
the stuffing box, end of the cylinder and gives steam by the end ports to the
piston B', which then makes a stroke giving steam by the end ports to the piston B
when the pistons continue working in the usual manner.
It will be obvious that it is immaterial to which end of the cylinder the steam is
admitted by the supplemental ports, or which piston is adapted to be first set in
motion, as the supplemental ports can be so arranged as to admit steam to either
end of either cylinder, and to open the other end of the said cylinder to the
exhaust.
In ordinary working the supplemental ports in the one piston have always passed
the supplemental ports in the cylinder before the same ports in the other piston
have arrived at them, so that the communication as shown in Figure 4, Sheet No. 2
is never established unless one of the pistons is out of its proper position with respect
to the other, and both pistons are so placed that neither can give steam to the other
by the end ports.
We wish it to be particularly understood that we do not limit ourselves to the
exact construction and arrangement of the supplemental ports as herein described
and illustrated by the accompanying drawing, but hold ourselves at liberty to
make such changes and alterations as fairly fall within the spirit and scope of our
invention

page_text: Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is ;-
1st. The improvement in steam and other fluid engines and pumps having duplex
cylinders the pistons of which act as distributing valves to the said cylinders, as and
for the purpose set forth.
2nd. In an engine having duplex cylinders the pistons of which act as distributing
valves to the said cylinders, the combination of the supplemental ports located centrally
in the pistons and cylinders and adapted-when both pistons are in such a position
that neither can give steam to, or exhaust from, either end of the other by the usual
means to put the one end of one cylinder in communication with the steam, and the
other end thereof in communication with the exhaust, as and for the purpose set.
forth.
3rd. In an engine having duplex cylinders the pistons of which each act as a
distributing valve to the other cylinder, the combination with the usual ports and
passages for the induction and eduction of the steam; of the two supplemental
ports H and H¹ connecting the bores of the two cylinders A and A¹; of the two
supplemental ports b and b¹ in the piston B, the former adapted to put the supple-
mental port H in communication with the steam chest C, and the latter adapted to
put the supplemental port H¹ in communication with the exhaust port d of the
cylinder A; and of the two supplemental ports 62 and 68 in the piston B', the
former adapted to put the supplemental ports H and H' in communication with
the outer and inner steam ports cl, el, respectively of the cylinder A1, all combined,
arranged, and operating, as and for the purpose set forth.
Dated this 13th day of October 1890.
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer and Patent Agent,
Royal Courts Chambers, 70-72, Chancery Lane, London, W.C.,
Agent for the Applicants.