Year: 1887

page_text: Date of Application, 2nd May, 1887
Specification Accepted, 19th July, 1887.
[Communicated from abroad by JESSE FAIRFIELD CARPENTER, of No. 19, Leipziger
Platz, Berlin, in the Empire of Germany, Engineer.]
PERFORD,
I, HENRY HARINGTON LEIGH, practising as Phillips & Leigh, of No. 22, South-
ampton Buildings, Chancery Lane, in the County of Middlesex, Engineer & Patent
Agent, 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 differential valve-gear for reciprocating piston
engines worked by steam or other elastic fluid pressure, and consists in the combina-
tion with the valve rod of a pair of springs, a double incline, and an engaging and
releasing detent by means of which the valve, which is loosely attached to the valve
rod, is kept stationary on its seat during the major part of the stroke of the piston,
and then moved from one terminal position to the other according as the valve rod is
moved by the piston.
I attain the objects of my invention by means of the mechanisms illustrated in the
following figures in which
Fig. I is a longitudinal sectional elevation of cylinder and valve chest.
Fig. 2 is a transverse sectional elevation taken on the line Y-Z of Fig. 1.
Fig. 3 is a side elevation, partly in section, of the detent and valve.
Fig. 4 is an end elevation of the valve.
Fig. 5 is a longitudinal sectional elevation illustrating a modification of the
invention.
Fig. 6 is an end elevation of the detent as illustrated in Fig. 5.
Fig. 7 is a sectional elevation of the valve; and
Figure 8 is a sectional end elevation of the same.
Referring to Figs. 1 to 4, A is the cylinder; B, the piston; and B', the piston rod.
The latter is tubular for the purpose of receiving the valve rod C with the head of
which c and the shoulder c¹ thereon the piston engages alternately by the plate b.

page_text: D is the valve chest axially continuous with the cylinder A. The respective ends
of the valve chest, d and d¹, are used as guides for the valve rod C. The usual ports, e
supply to valve chest, e¹ e² supply to cylinder, and e³ exhaust, are cored out in the
sides of the valve chest.
F is a saddle piece fast on the rod C and has inclines ff¹ formed upon it. These
inclines slope towards each other and form at their junction an internal angle as
shewn.
G is a detent; and g, an extension of the valve chest, its case and guide.
Declines g g are formed upon the detent and these slope away from each other;
their junction forming an external angle equal to the internal one formed by the
junction of the inclines f,f.
Three projections 91, 96, 98 are formed upon the outer end of the detent, the central
one g being shorter than the others.
H is the slide valve through which the valve rod C can move freely. It has two
snugs h, h upon it which are however virtually but one as far as my invention is
concerned, for as the rod C passes centrally through the valve I duplicate, or rather
divide, the snug h; projections g*, g°, g; inclines f, f¹; and declines g², g³..
I fix two collars i, upon the valve rod, which alternately bear against the valve H
for the purpose of moving the latter.
I, I are a pair of springs upon the rod C, one on each side of the valve H.
The figures show the piston at the end of its right-to-left stroke, the valve on the
point of being moved to the left by the expansion of the right hand springs I¹ and
the exhaust open to the right hand side of the piston.
b
The operation of my invention constructed as above described is as follows.
Steam (or other equivalent motor fluid) admitted to the valve chest D will flow
along the port e¹ into the cylinder A and drive the piston B over to the left, i.e., into the
position illustrated. As it reaches the end of its stroke, the plate 6 engages with the
head c of the valve rod and pulls it and the saddle piece F after it, compressing
the spring I accordingly against the adjacent face of the valve H, which however
cannot yield to the pressure of the spring because of the detent G keeping it stationary
on its seat by its lugs go, 9 embracing the snug h. But the same motion of the rod
which compresses the spring I¹ is also driving the detent into its case g by bringing
the incline to bear against the decline g³. At the moment when the collar i touches
the valve H, the detent has been moved far enough into the case g to release the
valve which will then be driven over to the left by the extension of the spring I¹
until the snugh encounters the projection 9.
The steam port e¹ will then be closed and the opposite one e³ uncovered, whereupon
steam from the valve chest will flow into the cylinder along the port e to the left
hand side of the piston B, causing it to make a stroke from left to right and therefore
to, in due course, contact with the shoulder c on the rod C which will be pushed over
to the right. As it moves over, the spring g¹ forces the detent towards the valve
until the snug h on the latter is embraced by the two projections 9, 9. The decline g
is next engaged by the incline f, the spring I is compressed until the collar i reaches
the valve H, by which time the incline will have caused the detent G to release the
valve, whereupon the latter will be driven over to the right by the extension of the
spring I.
Figs. 5 to 8 illustrate a modification of my invention, according to which the valve
chest is formed on the side of the cylinder and the valve rod is actuated by means of
two levers having their fulcra in chambers communicating with both cylinder and
valve chest. These levers are alternately projected into the cylinder by the recipro-
cating stroke of the valve rod, and there alternately engaged by the piston as it nears
the end of its respective stroke. No saddle piece is used, the inclines being formed
upon the valve rod. The relative positions of the projections and the snug in the
detent and valve are reversed.
A is the engine cylinder; B, the piston; and B¹ the piston rod.
J is the valve chest ; j, j¹ the steam ports to the cylinder, and the exhaust port.

page_text: K is the valve rod working in guides k which are close the end of the steam chest,
and having the two inclines k¹k formed upon an enlargement of it.
L, L' are the levers; 1, 1, their fulcra; and 12, 13, their chambers.
M, M' are fixed, and N, N¹, loose collars upon the valve rod. 0,0¹ are the spiral
springs on the valve rod.
P is the detent; p, its guide; p¹, its spring; p², p³, its declines; and p², its tooth.
Q is the slide valve; and q, q³, and q², the three projections thereupon.
The detent P and valve Q reach each other around in the enlargement of the rod C.
Fig. 5 shews the piston B at the end of its right-to-left stroke. It has engaged
with the lever L and caused it to move the valve rod over to the right, thereby
bringing the loose collar N into contact with the valve Q, compressing the spring Ŏ
between the two collars M and N, and disengaging the detent tooth p³ from between
the valve projections q², q³.
The consequent extension of the spring O moves the valve to the right, uncovering
the port and closing the port j¹. Steam will thereupon flow along the former port
to the left of the piston and drive it through its left-to-right stroke. As it nears the
end of the stroke it will through the lever L' move the valve rod over to the left,
during which motion the detent will be forced down the incline k¹ and its snug p
made to engage with the valve between the projections q, q'. The incline k² will next
engage with the decline p³, the collar N' with the valve Q, and the spring O¹ be
compressed. As soon as the valve is again released by the incline continuing to
force the detent back into its case, the extension of the spring O' will throw the valve
over to the left, again closing the port ; and opening the port j¹; a series of motions
which will result in the several parts again assuming the position illustrated in the
figure.
I wish to point out that I do not confine myself to the device of levers projecting
into the cylinder, to be there engaged by the piston for the purpose of actuating the
valve rod; inasmuch as the rod itself may be extended in either direction and its ends
returned so as to alternately project into the cylinder as far as would be necessary for
the piston to engage them in turn. It would, of course, be necessary with this last
described modification to reverse the relative positions of the valve chest mouths of
the steam portsj and j¹.
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 :-
The combination of valve rod operated intermittently by the reciprocating piston of
the engine; two inclines rigidly connected to said rod; a detent kept in contact by
elastic pressure with said valve rod, and alternately engaging and releasing the slide
valve; and a pair of springs alternately compressible between the slide valve and
extensions on the valve rod by the motion of the valve rod; substantially as and for
the purposes hereinbefore set forth.
ሳሰ J Amil 1887