Year: 1899

page_text: Date of Application, 3rd May, 1899
Complete Specification Left, 3rd Feb., 1900-Accepted, 3rd May, 1900
I, WILHELM SCHMIDT, of Wilhelmshöhe, near Cassel, in the Province of Hesse-
Nassau, German Empire, Engineer, do hereby declare the nature of this invention
to be as follows:-
The present invention relates to piston valves more especially to an improved
packing for the same. In piston valves of great diameter the tightness of the
piston is not sufficient, and special junk-rings are necessary to secure a perfectly
tight joint.
Hitherto closed rings were arranged on the valve in such a manner, that the
former could expand independently from the latter. Also open rings were used
to that effect, but the closed rings offered the advantage, that a compressing by
the exterior pressure was impossible.. With open rings a drawback is that some-
times they close too tight and consequently stop the valve suddenly. The open
rings, that is to say, the so-called self-regulating junk rings, are compressed
when steam is admitted from the inside and the pressure behind the ring is
less, than before the rings, whilst at the other side, during the expelling of the
steam a super-pressure behind the rings will be noticed by a strong pressure of
the rings against the side walls.
The object of my invention is to do away with all these drawbacks; I attain
this purpose by arranging small openings within the open junk-rings, and this
without loss of steam occurring. I am quite aware that when openings were pro-
vided in the junk-rings hitherto employed, the pressure before and behind the
rings would be equalled but also an immense loss of steam is the consequence.
I obviate all these inconveniences by an open junk-ring being of step form at
the inside face. This ring is enclosed by two closed rings also of step form and
effecting laterally the joint. The tightness of this joint is increased when the
steam presses laterally against the closed ring. I provide the open ring with
perforations, but a loss of steam is impossible for the reason that the closed rings
prevent the free passing of the stean.
Instead of employing one open ring enclosed by two closed rings. I also may
use two open rings embracing one closed ring, also in order to render the con-
struction more simple. I omit the closed rings and I only employ two open rings
provided with perforations.
1000
I, WILHELM SCHMIDT, of Wilhelmshöhe, near Cassel, in the Province of Hesse-
Nassau, German Empire, Engineer, do hereby declare the nature of this invention
Die S1

page_text: and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
The present invention relates to piston-valves more especially to an improved
packing for the same. In piston valves of great diameter the tightness of the
piston is not sufficient, and special junk-rings are necessary to secure a perfectly
tight joint.
Hitherto closed rings have been arranged on the valve in such a manner, that
the former could expand independently from the latter. Also open rings have
been used to that effect, but the closed rings offer the advantage, that compression
by exterior pressure is impossible. With open rings a drawback is, that some-
times they close too tight and consequently stop the valve suddenly. The open
rings, that is to say, the so-called self-regulating junk rings, are compressed.
The open rings( suffer from the drawback that at the beginning of the steam
admission, or during the period of compression, when the steam pressure on one
side of the rings is lower than on the other they become compressed and that
during the period of exhaustion an excess-pressure on one side of the rings
presses the latter too tightly against the side-walls of the piston-valve.
This invention has for its object to free the open rings of these drawbacks, by
arranging small openings within the open rings while preventing at the same time
any loss of steam. The arrangement of openings in closed junk-rings hitherto
employed would balance the pressure before and behind the rings so that a com-
pression by exterior excess-pressure would not take place, but this would not
prevent a loss of steam, because on one side of the ring is admission steam, while
at the other side is exhaust steam or vacuum. Since it is not possible to fit a
ring with mathematical exactness so that it should close hermetically, it is
necessary to employ particular arrangements, enabling the steam itself to effect
the tightening on the sides.
In order to make my invention more clear, I refer to the accompanying drawing,
in which:
Figure 1 is a vertical section through a junk-ring step-formed at the inner
surface,
Figure 2 is a top-view of the same.
Figure 3 is a detail view showing the superposition of the junk-rings.
Figures 4 & 5 represent vertical sections through modified constructions,
Figure 6 is a transverse section through a piston-valve showing the special
arrangement of the packing.
Figure illustrates a vertical section through a piston valve with two different
constructions of packing.
C
Figure 1 illustrates an open ring of step-form at the inside pace.
This ring
is enclosed by two closed rings b and c also of step form and effecting laterally
the joint. The tightness of this joint is increased when the steam presses laterally
against the closed ring c. I provide the open ring with perforations, but a
loss of steam impossible for the reason that the closed rings prevent the free
passage of the steam. The latter entering in the direction indicated by the
arrow passes through the perforations of the ring a, as illustrated by small
arrows a.. Thus the tension in these ring-formed spaces which are opened to the
entering steam is equal to that in the steam-channel. The ring spaces behind
the same, ris. at the side of the exhaust steam, are not yet influenced from the
steam and the pressure is thus equalled step by step according to the ring opening.
Herein is an essential feature of my invention.
In order to prevent the steam entering at the back-side from passing through
the joint of the rings, the cut of the ring is not made in a straight line but in
the manner illustrated in Figure 2. Besides projections c¹¹ of the closed
rings (Figures 1 & 3) are arranged in such a manner that they rest upon the
nieces S. being the connection pieces of the casing in the steam channel.
Evidently the free inflowing of the steam is not prevented by these arrangements,

page_text: Figure 6 shows a transverse section, Figure 7 a vertical section of a piston
valve with a modified form of an arrangement of rings. It is advantageous to
have the noses formed by the cut in the rings projecting downwards, so that the
junk-ring a with the surrounding rings b and c, which latter have some play in
the piston valve, press against the valve owing to their own weight. Thus a
safe joint is formed. Owing to the closed rings b and c pressing against the
valve a safe closure of the joint of the open ring a is effected at the inside and
consequently the particular ring spaces are not in communication through the
joint of the ring a.
Instead of employing one open ring enclosed by two closed rings I also may use
two open rings d d embracing a closed ring e, the open rings being provided
with perforations, as shown in Figure 4. The ring d is of angular section, the
shorter side of the angle projecting inwards in regard to the piston body, is
pressed by the steam against the closed ring e. The smaller ring is also of
angular section and arranged thus, that the longer side of the angle projecting
inwards is pressed by the steam against the piston body.
In order to allow an extension of the ring which during the operation is
heated more than and e.the longer leg has some play in the direction of the
movement of the piston valve, so that, when extended till its connection with the
shorter side of the ring d the ring effects a tight joint. By this arrange-
ment which is very simple, three inner ring-spaces are provided, separated from
one another.
Figure 5 illustrates another modification still more simple than the before ex-
plained construction represented in Figure 4. In this modification a closed ring
is not employed at all. The inner space is rendered tight against the entering
steam in a manner similar to that illustrated in Figure 4, viz. by an annular
projection respectively by the surface indicated by an arrow. In these con-
structions there are only two inner spaces separated from another. The joint
not being protected against the passage of steam, a special closing device must
be provided.
Figure represents as an example a vertical section through a piston valve
arranged within the casing. At the one side junk-rings as per Figure 1, and
at the other side rings as per Figure 4 are employed for rendering. tight the
piston valve.
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. Junk-rings for piston-valves having step-formed surfaces, for the purpose of
tightening against one another the separate ring spaces and of rendering equal
step by step the pressure within the valve, substantially as described:
2. The improved arrangement and form of junk-rings in piston-valves, substan-
tially and for the purpose as described.
GEO. H. RAYNER,
Agent for the Applicant, 37, Chancery Lane, London, W.C.