Year: 1898

page_text: Date of Application, 29th Oct., 1898..
Complete Specification Left, 25th July, 1899-Accepted, 26th Aug.,
1899
атро
I, GEORGE JACKSON CHURCHWARD, of Fairholme, The Drove, New Swindon,
Wilts, Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to the piston valves used for the distribution of steam
in steam engines, and consists in the method of keeping such valves steam tight
in their working cylinders or casings.
The features of my invention are, using solid packing rings, of a comparatively
soft metal, the desired extension of the solid body or mass of comparatively
soft metal to compensate for wear, being carried out by the said rings being
pressed against the inclined or coned surfaces of the recess, in the body of the
piston, by springs, (in some instances assisted by steam), so as to automatically
take up the wear. By this method of packing I do away with the necessity for
using the bridges or bars across the ports, or openings in the cylinder or casing,
which are necessary in all other piston valves, I thus obtain a much larger area
of passage for the steam, with the same diameter of piston valve than is possible
with those having split or jointed packing rings.
In all packing rings for piston valves there is a split or joint in order to permit
of the expansion of the rings for the purpose of compensating for the wear of
rings, and of the cylinder or casing. The existence of these joints or splits
necessitate the provision of bars or bridges to the ports or openings in cylinder
or casing, over which the piston or piston valve passes.
Now by my invention I avoid entirely the splits or joints in the packing rings
and use solid rings relying upon the expansion of the body or mass of com-
paratively soft metal, forming the rings, to compensate for the wear of the
cylinder or casing and the rings.
This desired expansion or extension of the body or mass of comparatively soft
metal, forming the packing rings, I accomplish by the use of suitable springs,
and in some instances assisted by steam pressing the packing rings against the
inclined or coned surface of the grooves or recesses in the body of the piston as
hereinafter described.
A suitable construction for a piston valve according to this invention is for the
two packing rings, which are each a solid mass of metal, to be made with one side
coned, and the opposite side straight, so that when in position, the straight sides
of the rings are opposite. each other, the bevelled or coned edges abutting against
similar bevelled or coned edges on the sides of the grooves, or recesses formed
in the piston head, in the straight sides of the rings are a number of recesses in
which are arranged spiral springs to force the comparatively soft metal rings
endwise on to the bevel or cone of the piston head, the comparatively soft metal
of the ring is thereby expanded so as to always compensate for the wear of the
rings and the face of the cylinder or casing in which the piston valve is working.
In order that the aforesaid solid ring may be placed in the usual groove on the
piston head, I use a junk ring on one side connected by bolts to the piston head,
or a divided piston head connected together by a nut on the end of piston rod.

page_text: As the elasticity of the springs may not in all cases be sufficient to give the
requisite end pressure for the extension of the body of comparatively soft metal,
of which the rings are made, I sometimes find it essential to utilise the steam
in the cylinder or casing to act on the straight edge of the rings.
Instead of the aforesaid construction in which I have described, two rings with
the springs arranged between, I sometimes use two rings, bevelled on both sides,
one side of each ring bearing against the piston head, while the other side bears
against hard metal rings provided with a bevelled or coned edge on one side,
and a straight edge on the other side, in this straight edge are a number of
recesses in which are placed spiral springs to give the requisite end pressure to
the hard rings so as to distend the comparatively soft rings as hereinbefore
described. The springs may be assisted by steam pressure as before.
I have described spiral springs to distend the rings, but it is obvious that
corrugated leaf springs or other types could be used.
In some instances groove or grooves are cut in the outer circumference of the
comparatively soft metal rings.
The rings in which are placed the springs for giving the requisite end pressure
may be made to overlap each other, so as to prevent steam when used to assist
the springs from passing to the outer circumference.
It is obvious that without departing from the nature of my invention, that I
may use the herein before described comparatively soft metal rings for pistons.
In such cases when the steam is used to assist the springs I place a valve in the
piston so that the steam may close this valve as it comes into either end of the
cylinder, so preventing the steam passing to the opposite end thereof; or other
similar devices may be used.
The mixture of bronze or other composition of soft metal to be used for the
herein before described packing rings, should be of a suitable ductility to permit
the springs to distend the metal, the correct amount for compensating the wear
taking place.
Dated this 28th day of October 1898.
Improvements in Engine Piston Valves.
I, GEORGE JACKSON CHURCHIWARD, of Fairholme, The Drove, New Swindon,
Wilts, 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:-
-
This invention relates to the piston valves used for the distribution of steam
in steam engines, and consists in the method of keeping such valves steam tight
in their working cylinders or casings.
The features of my invention arc, using solid or unsplit packing rings, of a
comparatively soft metal the desired extension of the solid body or mass of com-
paratively soft metal to compensate for wear being carried out by the said rings
being pressed against the inclined or coned surfaces of the recess, in the body of
the piston, by springs so as to automatically take up the wear.
By this method of packing I do away with the necessity for using the bridges
or bars across the ports or openings in the cylinder or casing which are necessary
in piston valves. I thus obtain a much larger area of passage for the steam, with
the same diameter of piston valve than is possible with those having split or
joined packing rings.

page_text: It is usual in packing rings for piston valves to have a split or joint in order
to permit of the expansion of the rings for the purpose of compensating for the
wear of rings: and of the cylinder or casing. The existence of these joints or
splits necessitate the provision of bars or bridges to the ports or openings in
cylinder or casing over which the piston or piston valve passes.
Now by my invention, I avoid entirely the splits or joints in the packing rings
and use solid rings, relying upon the expansion of the body or mass of com-
paratively soft metal, forming the rings, to compensate for the wear of the cylinder
or casing and the rings.
This desired expansion or extension of the body or mass of comparatively soft
metal forming the packing rings, I accomplish by the use of suitable springs.
A suitable construction for a piston valve, according to this invention is for
the two packing rings, which are each a solid or unsplit mass of metal, to be
made with one side coned and the opposite side straight, so that when in position,
the straight sides of the rings are opposite each other, the bevelled or coned edges
abutting against similar bevelled or coned edges on the sides of the grooves or
recesses formed in the piston head. In the straight sides of the rings are a
number of recesses in which are arranged spiral springs to force the comparatively
soft metal rings endwise on to the bevel or cone of the piston head, the com-
paratively soft metal of the rings is thereby expanded so as to always com-
pensate for the wear of the rings and the face of the cylinder or casing in which
the piston valve is working. In order that the aforesaid solid or unsplit rings
may be placed in the usual groove on the piston head, I use a junk ring on one
side connected by bolts to the piston head, or a divided piston head connected
together by a nut on the end of piston rod.
Instead of the aforesaid construction in which I have described (two. rings
with the springs arranged between) I sometimes use two rings bevelled on both
sides, one side of each ring bearing against the piston head while the other side
bears against hard metal rings provided with a bevelled or coned edge on one
side, and a straight edge on the other side, in this straight edge (of the hard metal
ring) are a number of recesses in which are placed spiral springs to give the
requisite end pressure to the hard rings, so as to distend the comparatively soft
metal rings as herein before described.
I have described spiral springs to distend the rings, but it is obvious that
corrugated springs or other types could be used.
In some instances groove or grooves are cut in the outer circumference of the
comparatively soft metal rings.
The mixture of bronze or other composition of soft metal to be used for the
herein before described packing rings, should be of a suitable ductility to permit
the springs to distend the metal, the correct amount for compensating the wear
taking place.
In the accompanying drawings, Fig. 1 shows a half section and half elevation,
of one of the heads of a piston valve, showing one method of adapting my pack-
ing rings in which a and a represents the two halves of the piston head with
circular flanges b and 6' having inclined or bevel surfaces on the inside.
Between the flanges are placed the solid or or unsplit metal rings e, e¹ of com-
paratively soft metal, bevelled so as to coincide with the bevel on the flanges of
the piston head. Sufficient clearance must be allowed between the vertical
side surface of the solid packing ring and the vertical surface of the piston head
flange so as to allow for the end movement of the ring, as wear is taken up,
as indicated by letter 7. In the body of the packing rings are a number of
horizontal recesses g g in which are placed spiral springs h for imparting the
necessary endwise pressure to expand the rings, against the internal surface of
the cylindrical valve casing, to compensate for wear. The internal surface of the
packing ring is made a working fit over the external surface of the body of the
piston head, as indicated by letter i.

page_text: Fig. 2 is an end elevation of the flat side of the packing ring showing the
recesses in which are placed the springs.
The piston head is shown made in halves so as to admit of the solid or unsplit
rings being placed over the body of the piston and secured to the rod j so as to
be perfectly rigid.
It is obvious that instead of the piston head being made in two halves it may
be made solid and provided with a junk ring, in lieu of the solid flange, so as to
admit of the solid packing or unsplit rings being placed on the head.
Fig. 3 is a half section and half elevation of a piston head as hereinbefore
described with reference to Fig. 1, but with a modification in the arrangement of
the solid or unsplit rings of comparatively soft metal, these rings having both
edges bevelled. Two rings of hard metal suitably bevelled and having recesses
for the expanding springs are placed between the comparatively soft metal pack-
ing rings as shown.
The necessary endwise pressure is given to the hard metal rings by springs
arranged in the horizontal recesses acting in the manner herein before described.
Fig. 4 is an end elevation of the solid metal ring showing the recesses for
holding the expanding springs.
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 piston valves used for the distribution of steam in steam and other fluid
pressure engines, the arrangement and combination of the two solid or unsplit
metallic packing rings of comparatively soft metal each ring having one circum-
ferential edge bevelled, the rings being expanded axially (to compensate for wear)
by the surfaces being forced against the bevelled surface of hard metal by springs
arranged between the flat vertical surface of the said solid or unsplit rings of com-
paratively soft metal, the rings being confined between the two flanges of a piston
head, substantially as described with reference to the accompanying drawings,
Figs. 1 and 2.
2. In piston valves used for the distribution of steam in steam and other
fluid pressure engines, the arrangement and combination of two solid or unsplit
metallic packing rings of comparatively soft metal having both circumferential
edges bevelled, the rings being expanded axially (to compensate for wear) by
being sandwiched between hard metal surfaces the necessary endwise pressure
being obtained from springs arranged between the central hard metal rings, all
the rings being confined between the two flanges of a piston head, substantially
as described with reference to the accompanying drawings Figs. 3 and 4.
3. In piston valves for steam or other fluid pressure engines, the improved
arrangement and combination of hard metal rings with solid or unsplit rings of
comparatively soft metal having bevelled edges which are expanded axially by
endwise pressure exerted by springs substantially as described with reference to
the accompanying drawings and acting in the manner set for for the purpose
specified.
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