Year: 1887

page_text: 1. GEORGE JOHN CAVAN D'URBAN SKINNER, of Burnaby Villa, Claremont Road,
Highgate, in the County of Middlesex, 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 relates to an improved construction of that class of engines in which
the motive energy is produced by the pressure of an expansive fluid upon alternate
faces of a moving piston, the reciprocating linear motion of which is converted into a
continuous rotary one by establishing a mechanical connection between the piston and
the throw of a crank.
The invention consists in
1st. Dispensing in a double-acting engine with the usual connecting rod, making
the junction between the piston-rod and piston by means of a flexible joint, and
connecting the opposite end of the piston-rod direct to the crank pin.
2nd. Making the cylinder cover, or that part of it in the plane of the throw of the
crank, concave and therefore capable of sliding backwards and forwards upon a
correspondingly convex seat upon the cylinder end.
3rd. Providing the stuffing box in the sliding cylinder cover with a ball-and-socket
joint through which the piston-rod communicates the energy of each succeeding
throw to said cover without shock.
4th. Providing the sliding cylinder cover with a spiral spring supported on each
side of the piston-rod between it and a projection from said cover, through which
springs the piston-rod and communicates the energy of each succeeding throw to
said cover without shock.
5th. Providing longitudinal piston-guides springing from the cylinder end, placing
the steam ports within the cylinder, and providing an internal steam or working
cylinder.
6th. Forming steam ports in the sliding cylinder cover to regulate the communi-
cation between the steam chest and the working cylinder.
7th. The combination with the sliding cylinder cover of a reversing slide valve,
8th. An improved method in combination with the preceeding improvements of
supplying steam to the second cylinder of a tandem engine from the ports of the first
cylinder.

page_text: I attain the various objects of my invention by means of the mechanical arrange-
ments illustrated in the following figures in which
Fig. 1 is a side elevation illustrating the application of my invention to a single
double-acting inverted cylinder engine.
Fig. 2 is a half sectional elevation of the cylinder.
Fig. 3 is a sectional plan of the reversing valve and plan of the bottom end of the
cylinder, the slide valve and its cover having been removed,
Fig. 4 is a transverse sectional elevation taken on the line C-D of Fig. 2.
Figs. 5 and 6 are, respectively, plan and side elevation of a slide valve.
Figs. 7 and 8 are, respectively, inverted plan of the steam chest and plan of valve
illustrating an alternative construction of reversing valve.
Fig. 9 is an elevation of an alternative construction of piston.
Figs. 10 and 11 are, respectively, sectional elevation and plan of an alternative
device for preventing shock or jar in the motion of the slide-valve.
Fig. 12 is a sectional horizontal elevation illustrating the application of my invention
to a fandem engine.
A is the cylinder; a, its top cover; and a³, a² the ports to the top and bottom
faces, respectively, of the piston B which is connected to the end of the piston-rod C
by any suitable type of flexible joint b, for the lubrication of which suitable provision
is made in any well-known way. Piston guides 6, are provided for the purpose of
keeping the piston in a horizontal plane. Each guide has its lubricator which
feeds into a cavity formed within the piston.
An alternative construction of piston is shewn in Fig. 9. B' is the piston, of what
is known as the double-bucket type. It is shewn as connected to the piston rod by
a ball-and-socket joint c with stuffing box c¹. The joint is lubricated through an
opening formed in the top of the piston. Slots c³ are formed in the bucket rims
to coincide with the respective ports a', a². A second pair of slots is also provided to
be used by giving the piston a quarter-turn. Whichever type of piston be adopted,
the cylinder cover a and bottom flange a³ are recessed accordingly to permit of the
maximum length of stroke being made. When a piston as illustrated in Fig. 9 is used,
the guides shewn in Fig. 2 and described therewith may be dispensed with, their
function as guides being discharged by the bucket rims of the piston.
The bottom cylinder flange or end a³ is, for the purpose of my invention, made more
massive than usual, and extended internally towards the axis of the cylinder, leaving
a space at in which the piston rod C throws to-and-fro.
Its face, or preferably a central band across it, is made convex, the radius of the
are being the length of the stroke + the thickness of the piston + one clearance space.
The faces of the slide valve D are struck from the same centre as that of the
cylinder-end a. Packings d are recessed into the inner face of the valve, and
T-guides are provided to steady the travel of the valve.
E is a ball-and-socket joint through which the piston-rod C reciprocates. Stuffing
boxes e, e are provided for the purpose of preserving tight contact between the
various parts.
The object of the ball-and-socket joint is to allow each throw of the piston-rod C to
be communicated to the valve D smoothly and without jarring it.
An alternate device is shewn in Figs. 10 and 11.
F is a block sliding upon the convex face of the valve D with which it is kept in
contact by two guides f,sliding in studs f¹, f. A spiral spring is placed upon
each guide, between the block and the stud, through which the motion of the block
is gradually communicated to the valve D.
G is the bottom cover adapted to the contour of the valve D, and cut away in the
centre to allow of its to-and-fro travel.
H is the steam chest containing the reversing valve. It is fixed on the side of the
cylinder and preferably as near the slide valve D as is practicable. I is the inain
supply and J the exhaust.
K is the reversing valve fast upon its rod which latter connects with the hand-

page_text: lever by means of which the valve can be moved between its seat and the
diaphragm in either direction.
Antifriction rollers may be fitted in the face of the valve for the purpose of
diminishing the friction between it and its seat.
I is the supply port and 7, the exhaust ports. When the port L is opposite the
port the central port M. in the cylinder-end takes steam, the exhaust being through
the ports m into 1, 7. When the port L is opposite to the port steam is supplied
to ports m, m, the exhaust being through M, thereby causing a reverse motion on the
part of the piston.
The ports n, n in the valve coincide with ports m, M and M, m in the cylinder-
enda alternately. Ports N, N, and O, O correspond with ports a', a², respectively.
In the alternative reversing valve illustrated in Figs. 7 and 8, the ports m', M³, m
are counterparts of the ports m, M, m, in Fig. 3; while P is the exhaust port. The
valve itself K has one port L' passing through it, the reversing being effected in
the same way as with the valve illustrated in detail in Fig. 3 and described therewith.
I wish it to be distinctly understood that my invention is not confined to any
particular type of double-acting reciprocating piston engine. I have illustrated the
invention in the accompanying drawings as applied to an inverted single cylinder
double-acting engine, but only as an illustration of, and not as limiting the scope of,
the invention, for it is clear that it is equally applicable to horizontal, compound,
coupled or tandem engines.
The application of my invention to a tandem engine is illustrated in detail in
Fig. 12.
:
R is the first, and R¹ the second, cylinder. The ports a', a² to the top and bottom
faces, respectively, of the pistons R2, R3, are formed in, the cylinder sides as described
with reference to Fig. 2, and are connected by pipes a³, a².
Any convenient arrangement of exhaust-device for the purpose of facilitating the
exhaust from the cylinder R₁ may be adopted.
In the figure, the pipes a³, a are drawn straight. It is obvious that my invention
does not confine me to this, as their shape may be modified according to the relative
diameters of the two 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 double-acting engine cylinder, the combination of convex cylinder-end,
concave slide-valve, and piston-rod reciprocating through both, substantially as
described with reference to the accompanying figures.
2. In a double-acting engine cylinder, the combination of piston-rod connected by
a flexible joint at one end to the piston and by the other end to the crank pin with a
concave slide-valve travelled to-and-fro by the throw of the piston-rod upon the
convex face of the cylinder-end, substantially as described with reference to the
accompanying drawings.
3. In a double-acting engine cylinder, the combination of longitudinal piston-guides
with a piston connected direct to the crank pin, and having within it annular lubricant
cavities for the purpose of lubricating said guides, substantially as described with
reference to the accompanying figure 2.
4. In a double-acting engine cylinder, the combination with a piston-rod connected
direct to piston and crank pin, of a concave slide-valve travelled by said piston-rod
upon the convex end of the cylinder and of a ball-and-socket connection between said
piston-rod and valve, substantially as described with reference to the accompanying
figure 2.
5. In a double-acting engine cylinder, the combination with a piston-rod connected
direct to piston and crank pin and a concave slide-valve travelled by said piston-rod
upon the convex end of the cylinder, of a block (through which the piston-rod works)
capable of a sliding motion upon the convex face of the slide-valve, spiral springs,
studs and guides, substantially as described with reference to the accompanying
figures 10 and 11,

page_text: 6. In a double-acting engine cylinder, the combination of a concave slide-valve
travelled to-and-fro by the throw of the piston-rod upon the convex end of a cylinder
and having ports formed within it, with a steam chest and ports leading to the
respective faces of the piston, substantially as described with reference to the
accompanying drawings.
7. In a double-acting engine cylinder, the combination with a concave slide-valve
travelled to-and-fro by the throw of the piston-rod upon the convex end of a cylinder
and having ports formed within it, of a reversing valve in the steam-chest communi-
cating with the ports in said slide-valve, substantially as described with reference to
the accompanying figures.
8. In a double-acting cylinder tandem engine, providing for the passage of steam
from one cylinder to the other by means of pipes which make connection between
adjacent ends of the ports in the respective cylinders, substantially as described with
reference to the accompanying figures.