Improvements in or connected with Metallic Packings, applicable for use in Steam and other Fluid-pressure Engines or Machines.
Year: 1890

page_text: Date of Application, 21st Jan., 1890
Complete Specification Left, 21st Oct., 1890--Accepted, 22nd Nov., 1890
PROVISIONAL SPECIFICATION.
Improvements in or connected with Metallic Packings, applicable
for use in Steam and other Fluid-pressure Engines or Machines.
We, HENRY EDWARD BEDFORD, and GEORGE RODGER, both of Waltham Buildings,
Holborn Circus, London, Engineers, do hereby declare the nature of our said invention
to be as follows:-
The type of piston packing rings to which this invention chiefly relates is that in
which the rings are held out from the piston against the inner surface of the cylinder
in which they work, by means of the pressure of the steam or other fluid working in,
or being operated upon in, such cylinder. Piston packings of this type have hitherto
been designed with certain defects and faults, and the chief object of the present
invention is to provide a packing without such defects and faults..
Generally speaking, in all previous arrangements the whole area of the packing
ring which is in action has been subjected to the pressure of the steam or other fluid,
while it is impossible, (under working conditions) that the pressure tending to press
the ring inwards, that is, away from the cylinder shell could at all equal the pressure
from within on the back of the packing ring. In consequence of this disproportion
between the pressure on the opposite sides of the ring it has been found that rings of
this type wear away rapidly thus indicating undue and unnecessary friction and con-
sequent loss of power.
By our arrangement and construction of piston packing and rings as hereinafter
described, and according to our invention, we are enabled to obviate this wear and
loss of power.
According to our invention steam is only admitted to a portion of the internal area
of the ring; that is to say, only a sufficient proportion of such internal area is sub-
jected to the pressure of the working fluid to provide for said ring being pressed
gently but sufficiently outwards against the cylinder shell.
In one example of piston rings operating according to our invention there is
comprised the body of the piston; the packing rings; a separate ring acting as a
carrier for the rings; and an ordinary junk-ring. The rings in cross section have the
figure of an angle bar, and the carrier ring at the upper lower edges is formed with
corresponding recesses in the form of steps: both the rings are, in this example of
piston, held in position in the piston by the junk ring. Usually, and in ordinary
cases, only one ring is in action at a time, and that ring is the one on the side of the
piston on which for the time being, the greater pressure exists. The result of the
construction as described in the example of our invention is that two annular recesses
or chambers are formed behind each ring, and a sliding joint is also formed between
the ring and the step of the carrier, so that no communication exists between these
two chambers; on the other hand communication between one of such chambers and
the cylinder is provided and effected by suitable apertures; and also, communication
between the other chambers and the external working face of the piston (i.e. the
carrier ring) between the packing rings, is made by providing small apertures in the
carrier ring; thus whatever pressure exists in the cylinder, it will also exist in one of
the said annular chambers, and whatever pressure exists between the face of the
carrier ring and the face of the cylinder walls, the pressure will also be in such
chambers. Consequently the pressure acting on the internal surfaces of the packing
rings tending to press them outwards, is the mean of those in the two chambers.
Then as regards the external pressures tending to press the rings inwards, i.e. away
from the walls of the cylinder, that pressure will vary between the pressure at the
two edges of the rings. It only remains to proportion the relative areas of the two

page_text: portions of the packing rings acted upon by the pressure of fluid in the annular
chambers so that the pressure outwards shall be slightly in excess of the pressure
inwards. When this is done the piston will be perfectly tight with the least possible
friction.
It will be understood that the packing rings are cut and tongued by a tongue piece
of angular form fitting over the edge and back of the rings and they are arranged
and fitted so that when the junk ring is fixed in position they will be free to move
easily in the horizontal plane with respect to the axis of the piston.
We wish it understood the invention is not confined to the precise disposition and
arrangement of parts herein described, as in the example of the invention given; as,
for instance, it will be evident that in applying the invention to pistons, of steam
engines, air engines, gas engines, machinery for compressing air, and other gases
or vapours, rams, pump pistons, piston valves, and so forth the parts, or some of
them, will be modified in arrangement and construction, i.e., in detail, to suit such
application; and again, in single acting engines or machines one ring only will be
required, and so on.
Dated this 20th day of January 1890.
CHEESBROUGH & ROYSTON,
15, Water Street, Liverpool, Applicants' Agents.
COMPLETE SPECIFICATION.
Improvements in or connected with Metallic Packings, applicable
for use in Steam and other Fluid-pressure Engines or Machines.
We, HENRY EDWARD BEDFORD, and GEORGE RODGER, both of Waltham Buildings,
Holborn Circus, London, Engineers, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
The type of piston packing rings to which this invention chiefly relates is that in
which the rings are held out from the piston against the inner surface of the cylinder
in which they work, by means of the pressure of the steam or other fluid working in,
or being operated upon in, such cylinder. Piston packings of this type have hitherto
been designed with certain defects and faults, and the chief object of the present
invention is to provide a packing without such defects and faults.
Generally speaking in all previous arrangements, the whole area of the packing ring
which is in action has been subjected to the pressure of the steam or other fluid, behind
it, and it is impossible, (under working conditions) that the pressure tending to press
the ring inwards, that is, away from the cylinder wall or surface, could at all equal
this pressure from within on the back of the packing ring tending to press it outwards.
In consequence of this disproportion between the pressure on the opposite sides of the
ring, a large amount of undue and unnecessary friction, and consequent loss of power
is caused, and the rings wear away more or less rapidly.
By our arrangement and construction of piston packing the rings as hereinafter
described and according to our invention this wear and loss of power are obviated.
According to our invention steam or other fluid is admitted to a portion only of
the internal area of the ring; that is to say, only a sufficient proportion of such
internal area is subjected to the pressure of the working fluid to provide for said
ring being pressed gently but sufficiently outwards against the cylinder wall or
surface.
In order that our invention, and the means which we employ in carrying it out
may be clearly understood, we will proceed to describe it by the aid of the accom-
panying sheet of drawings which illustrate an example of packing rings according to
our invention. The drawings are marked with letters and figures of reference corre-
sponding with those used in the following explanation.

page_text: Figure 1 is an elevation of the piston, shewn partly in section fitted and provided
with packing rings according to our invention:
Figure 2 shews a half plan of the piston partly in section; and
Figure 3 is a section of the packing ring.
Figure 4 shews a modification of our packing.
With reference to the drawings, A is the body of a piston; P are the packing
rings; B is a separate ring acting as a carrier for the rings P; and J is an ordinary
junk-ring. It will be observed that the rings P have in cross section the figure of
an angle bar, and the carrier ring B at the upper and lower edges is formed with
corresponding recesses in the form of steps: both rings are, in the example of piston
shewn in the figure, held in position in the piston by the junk ring B. In a piston it
will be understood that in ordinary cases, only one ring P is in action at a time, and
that that ring is the one on the side of the piston on which for the time being, the
greater pressure exists.
The result of the construction as described in the example of our invention, is, that
two annular recesses or chambers (102 are formed behind each ring P, and a sliding
steam tight joint at C³ is also formed between the ring P and the step of the carrier
ring B, so that no communication exists between these two chambers; on the other
hand communication between the chamber C¹ and the cylinder is provided and
effected by holes H (or equivalent provisions or construction), and also, commu-
nication between the chambers C2 and the external working face of the piston (i.e. the
ring B between the rings P, P,) is made by providing small grooves G (or equivalent
provisions in the carrier ring B); thus whatever pressure exists in the cylinder, it will
also exist in the chambers C, and whatever pressure exists between the face of the
carrier ring B and the face of the cylinder walls, that pressure will also be in the
chambers C. Consequently the pressure acting on the internal surface of the rings P
tending to press them outwards, is the mean of those in the two chambers C₁, C2.
Then as regards the external pressures tending to press the rings inwards-i.e. away
from the walls of the cylinder,-that pressure will vary between the pressure at the
point (which will be the same of course as that in the cylinder on that side of the
piston having upon it the greater pressure) and the pressure at the point y—which
pressure cannot be greater than that on the opposite side of the piston. It only
remains to proportion the relative areas of the two portions of the rings P acted upon
by the pressure of fluid in the chambers C and C² so that the pressure outwards shall
be slightly in excess of the pressure inwards. When this is done the effect will be
that the piston will be perfectly tight with the least possible friction, and all undue
wear and friction will be prevented.
The rings P are cut at p, and provided with a tongue piece 9 ; and they are so
arranged and fitted that when the junk ring is fixed in position, they will be free
to move easily in the horizontal plane with respect to the axis of the piston.
We wish it understood we do not intend to confine the invention to the precise
disposition and arrangement of parts herein set forth with reference to the drawings,
as for instance, it will be evident that in applying the invention to pistons of steam
engines, air engines, gas engines, machinery for compressing air, and other gases or
vapours, rams, pump pistons, piston valves, and so forth the parts or some of them
will be modified in arrangement and construction-that is in detail-to suit such
applications; and again, in single-acting engines or machines one ring only will be
required, and so on.
An example of a modified arrangement is shewn in Figure 4, wherein the ring has
an annular projecting part pl, and the steam or other fluid employed to press it out-
wards is admitted to the annular recess H. In this construction the steam or other
fluid acts upon the projecting portion p¹ tending to press the ring outwards: it may
also however be admitted to the chamber C' if desired.
And again, the invention above described has been specified as applied more

page_text: particularly to pistons, piston valves, plungers, and analogous parts of steam, and
other engines and machines, but it is to be understood that packing arranged and
constructed as herein described may also be applied to the rendering of piston
and other rod gland or like packings tight, in which case one-or more-of the
rings would be arranged in a stuffing box or space corresponding in form to the seat
for the ring in a piston, and adapted to be pressed inwards by the steam or other fluid
onto the rod, such fluid being admitted to an annular space or cha uber behind the
ring (say equivalent to (") from the cylinder or other fluid supply; or, in other
words, the packing may be used to pack rods by merely using the converse arrange-
ment of the packing shewn in the drawings; the packing being arranged round the
rod and pressed inwards onto the surface of the rod. Of course the rings if more
than one be used-in most cases would, in rod packings, be disposed in the same
direction, as the action of steam is nearly always, pressing in one direction, i.e., tending
to escape outwards except in cases where the fluid within the cylinder is below the
pressure of the atmosphere, when of course the rings would be arranged to suit such
a condition or, if the pressure be an alternating one, that is, at one time above, and
at another below that of the atmosphere, two sets of rings would be used and arranged
or disposed in their seats in opposite directions as in a piston.
Having now particularly described and ascertained the nature of this invon-
tion and in what manner the same is to be performed we declare that what we
claim in respect of the herein described invention is :-
1. The herein described mode of regulating or adjusting the pressure upon the
internal area or back side of the packing rings of pistons used in cylinders of steam
or other fluid pressure engines and machines (including valve cylinders), and of
piston and other rods, consisting in permitting or causing the fluid used in or
operated upon in said engines or machines to act only on a portion of the internal or
back area of such rings.
2. In, or for, fluid pressure engines or machines, the construction or arrangement
of piston and its packing ring or rings therefor, substantially as described, by which
the internal pressure on said ring or rings tending to press it or them outwards is
controlled or adjusted.
3. The combination of a packing ring or rings for pistons and working rods of
angle bar section, and a piston body, or a carrier ring therein, or other part, sup-
porting said packing ring, and having stepped recesses or grooves in which said ring
or rings fit and work; for the purposes set forth.
4. In a piston, the employment of a packing ring or rings of angle bar section said
ring or rings having its or their interior angle or angles inwardly disposed; sub-
stantially as shewn and set forth.
5. The packing rings P and stepped ring B arranged and adapted to operate
substantially as set forth with reference to the drawings.
6. In a piston and its packing of the kind bereinbefore referred to, the use of
passages or conduits (such as G) by which an annular chamber such as 2 behind the
ring communicates with the space at the periphery of the piston; substantially as
described for the purposes set forth.
Dated this 20th day of October 1890.
CHEESBROUGH & ROYSTON,
15, Water Street, Liverpool, Applicants' Patent Agents.