Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR OPTIMIZING A FLUID ENVIRONMENT IN SPLIT
MECHANICAL SEALS
Related Application
The present application claims priority to U.S. provisional patent application
Serial No.
63/311,724, filed on February 18, 2022, and entitled System And Method For
Optimizing Fluid
Environment In Mechanical Seals, and is a continuation-in-part patent
application of U.S. patent
application Serial No. 17/339,397, filed on June 04, 2021, and entitled
Externally Energized
Secondary Seals In Split Mechanical Seals, which claims priority to U.S.
provisional patent
application Serial No. 63/035,504, filed on June 05. 2020, and entitled
Externally Energized
Secondary Seals In Split Mechanical Seals. The contents of the foregoing
patent applications are
herein incorporated by reference.
Background of the Invention
Conventional mechanical seals are employed in a wide variety of environments
and
settings, such as for example, in mechanical apparatuses, to provide a fluid-
tight seal. The
mechanical seals are usually positioned about a rotating shaft or rod that is
mounted in and
protrudes from a stationary mechanical housing.
Split mechanical seals are employed in a wide variety of mechanical
apparatuses to
provide a pressure-tight and fluid-tight seal. The mechanical seal is usually
positioned about a
rotating shaft that is mounted in and protruding from stationary equipment.
The mechanical seal
is usually bolted to the stationary equipment at the shaft exit, thus
preventing the loss of
pressurized process fluid from the stationary equipment. Conventional split
mechanical seals
include face-type mechanical seals, which include a pair of seal rings that
are concentrically
disposed about the shaft and are axially spaced from each other. The seal
rings each have sealing
faces that are biased into sealing contact with each other. Usually, one seal
ring remains
stationary while the other seal ring is coupled to the shaft and rotates
therewith. The mechanical
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seal prevents leakage of the pressurized process fluid to the external
environment by biasing the
seal ring sealing faces into sealing contact with each other. The rotary seal
ring is usually
mounted in a holder assembly which is disposed in a chamber formed by a gland
assembly. The
holder assembly can have a pair of holder halves or segments secured together
by a screw.
Likewise, the gland assembly can have a pair of gland halves or segments that
are also secured
together by a screw. The seal rings are also often divided into segments. each
segment having a
pair of sealing faces, thereby resulting in each ring being a split ring that
can be mounted about
the shaft without the necessity of freeing one end of the shaft.
Prior art split mechanical seals have rotary and stationary components
assembled around
the shaft and then bolted on to the equipment to be sealed. A rotary seal face
is inserted into a
rotary metal clamp after the segments are assembled around the shaft. Then,
the stationary face
segments and gland segments are assembled and the split gland assembly is then
bolted to the
pump housing. Alternatively, the stationary and rotary sealing components can
be preassembled
into subassemblies that can then be mounted about the shaft.
Split mechanical seals that come in rotary and stationary halve assemblies
(e.g., four sub-
assemblies) have the split surfaces of the metal parts, the elastomer gaskets
and 0-rings, and the
primary faces all in line. This significantly increases the difficulty in
assuring that all the
components are constrained to come back into sealing alignment. For example,
as the 0-rings are
compressed radially inside their grooves, they expand circumferentially with
ends protruding,
potentially buckling when joined, thereby causing pinching by metal or seal
face parts at the
location of the split. The conventional method of staggering the splits of the
various parts within
the rotating or stationary assemblies cannot be utilized as whole sub-
assemblies are secured
around the shaft and not individual components. This facilitates and speeds up
the seal assembly
onto the equipment but can result in parts misalignment and subsequent
measurable leakage from
the joints formed by the sealing components.
Conventional split mechanical seal designs posed several problems for users of
the seals.
For example, the split mechanical seals often times did not adequately
circulate or remove
contaminates that reside in slurry like process fluids. The contaminants, if
left in place near the
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split seal faces, can adversely affect the sealing performance of the
mechanical seal and degrade
the operation and function of the mechanical seal over time.
Summary of the Invention
The present invention is directed to a mechanical seal assembly that includes
a gland
assembly having a chamber formed in an inner surface for seating a fluid
insert element. The
fluid insert element promotes movement of particles present in a slurry
process fluid away from
a seal interface formed by the sealing surfaces of rotary and stationary seal
rings.
The mechanical seal assembly of the present invention includes a gland
assembly having
a main body that includes an outer surface and an inner surface, where the
inner surface has at
least one gland chamber formed therein. A fluid insert element is provides and
is sized and
configured for mounting in the gland chamber. The fluid insert element has a
main body having
a non-planar bottom surface configured for being exposed to the slurry process
fluid in the gland
mounting region. The mechanical seal assembly also includes a holder assembly
forming a
holder chamber and disposed within the gland mounting region, a rotary seal
ring disposed
within the holder chamber of the holder assembly and having a main body having
a rotor sealing
surface formed at one end, and a stationary seal ring disposed within the
gland mounting region
and having a main body having a stator sealing surface formed at one end. The
stator sealing
surface and the rotor sealing surface are disposed adjacent to each other to
form a sealing
interface. The stator sealing surface and the rotor sealing surface have the
same size and shape.
The main body of the gland assembly has a first annular portion having a first
fluid port
formed therein that extends between the inner surface and the outer surface of
the gland
assembly. The first fluid port is positioned so as to be in fluid
communication with the gland
chamber. The main body of the gland assembly can also include a second annular
portion having
a second fluid port formed therein that extends between the inner surface and
the outer surface of
the gland assembly for introducing a fluid into the gland mounting region. The
first annular
portion can also include an optional third fluid port that is formed therein
and that extends
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between the inner surface and the outer surface of the gland assembly. The
third fluid port is
positioned so as to be in fluid communication with the gland chamber.
The bottom surface of the fluid insert element has a curved shape, that can
curve in a
lateral direction. Alternatively, the curved shape of the bottom surface of
the fluid insert element
can be curved in a medial direction. According to the present invention, the
bottom surface of the
fluid insert element can have a sloped surface. Specifically, the bottom
surface of the fluid insert
element can have a first sloped surface and an opposed second sloped surface
that are each
sloped at a first angle, and an intermediate sloped surface disposed between
the first and second
sloped surfaces that is sloped at a second angle, where the second angle is
greater than the first
angle.
According to one embodiment, the main body of the fluid insert element can
include a
top surface and a plurality of side walls coupled to the top surface, and a
tower portion extending
outwardly from the top surface. The tower portion can include a tower top
surface and a plurality
of tower side walls, where one or more of the plurality of tower side walls
has a side wall
opening formed therein. The tower top surface can also have a first fluid
opening formed therein
that is aligned with the first fluid port when the fluid insert element is
mounted within the gland
chamber. The top surface of the main body of the fluid insert element has a
second fluid opening
formed therein that is aligned with the first fluid opening.
The mechanical seal assembly of the present invention can also include a
stator sealing
element disposed about the outer surface of the stationary seal ring; an
axially movable spring
holder plate having a top surface and an opposed bottom surface and a radially
inwardly spaced
flange portion, wherein the top surface has a plurality of fastener apertures
formed therein; a
plurality of biasing clip assemblies configured for mounting about the spring
holder plate and for
mating engagement with the stationary seal ring for coupling the spring holder
plate to the
stationary seal ring; and a plurality of fasteners for mounting in the
fastener apertures and the
gland fastener holes and for securing the spring holder plate to the top
surface of the gland
assembly. The gland assembly has a top surface having a plurality of gland
fastener holes formed
therein. The stator sealing element is disposable in a radially uncompressed
state when in a first
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unloaded position and wherein the spring holder plate is movable in the axial
direction when the
plurality of fasteners arc tightened so as to move the stator sealing element
in the axial direction
into a radially compressed state when in a second loaded position. The top
surface of the gland
assembly has a plurality of spring holes formed therein and the seal further
includes a plurality of
springs for mounting in the plurality of spring holes.
The holder assembly can have an inner surface that has a holder detent groove
formed
therein. The rotary seal ring an also have a rotary detent groove formed in an
outer surface
thereof. Further, the stationary seal ring has an inner surface having a
groove formed therein for
coupling to a retaining portion of each of the plurality of biasing clip
assemblies. The biasing
clip assemblies include an inner spring element and an outer spring clement.
The inner spring
clip includes a main body having an inner ridge portion formed at a first
end thereof and
configured for engaging with a bottom surface of the spring holder plate, and
a bent portion
formed at a second opposed end and configured for engaging with the top
surface of the
stationary seal ring. The outer spring clip has a first coiled end that is
sized and configured for
seating in the bent portion of the inner spring clip and an opposed second end
having a bent tab
portion that is sized and configured for engaging with the groove formed in
the inner surface of
the stationary seal ring.
According to another aspect, the present invention is directed to a split
mechanical seal
that employs mechanical features that allow the seal to safely operate in
mechanical devices that
employ a slurry as a process fluid, such as for example in centrifugal pumps.
The mechanical
features utilize existing fluid motion, such as the rotating motion of fluids
around the shaft and
associated mechanical seal components, that originates from the boundary layer
of the
components to induce fluid flow and if desired to move, circulate, capture and
expel
contaminants present within the process fluid. The mechanical features of the
present invention
can include mechanical insert components that are installed in selected
channels formed at
selected locations along an inner surface of a gland assembly that is mounted
on the centrifugal
pump. Due to the inherent splits or joints present in a split mechanical seal,
continuous
concentric helical components are undesirable. The mechanical insert
components of the present
invention can be mounted in or reside in under-utilized segments, locations or
arcs of the gland
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element. For example, an annular cavity or chamber can be formed along an
inner surface of the
gland that is sized and configured for mounting the mechanical insert
component. The
configuration of the mechanical insert component can be varied and preferably
includes a main
body having a sloped or arcuate surface that faces the process fluid. Hence,
the configurations
can include open volume arrangements to complex geometries that induce fluid-
particle
movement and influence fluid currents within the mechanical seal assembly. The
purpose of the
mechanical insert component is to prevent particle impaction and/or to move
the particles away
from the seal faces of the seal rings. The protection of the mechanical seal
interface is important
to the operation and longevity of the split mechanical seal, thereby reducing
maintenance and
increasing the longevity of the mechanical seal.
Brief Description of the Drawings
These and other features and advantages of the present invention will be more
fully
understood by reference to the following detailed description in conjunction
with the attached
drawings in which like reference numerals refer to like elements through the
different views.
The drawings illustrate principals of the invention and, although not to
scale, show relative
dimensions.
FIG. 1 is a perspective view of the spilt mechanical seal of the present
invention.
FIG. 2A is a partial cross-sectional view of the mechanical seal showing the
sealing rings
and sealing elements in a disengaged unloaded position according to the
teachings of the present
invention.
FIG. 2B is a partial cross-sectional view of the mechanical seal showing the
sealing
elements associated with the sealing rings in a disengaged unloaded position
according to the
teachings of the present invention.
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FIG. 3A is a partial cross-sectional view of the mechanical seal showing the
sealing
elements associated with the sealing rings in an engaged loaded position
according to the
teachings of the present invention.
FIG. 3B is another partial cross-sectional view of the mechanical seal showing
the sealing
elements associated with the sealing rings in an engaged loaded position
according to the
teachings of the present invention.
FIG. 4A is a perspective view of the spring holder plate employed by the
mechanical seal
of the present invention that can be employed to move the sealing elements
associated with the
sealing rings into the engaged and unengaged positions according to the
teachings of the present
invention.
FIG. 4B is a perspective view of one of the spring holder segments of the
spring holder
plate according to the teachings of the present invention.
FIG. 5A is a partial cross-sectional view of the mechanical seal showing the
preassembled gland subassembly unit according to the teachings of the present
invention.
FIG. 5B is a partial cross-sectional view of the mechanical seal showing the
preassembled holder subassembly unit according to the teachings of the present
invention
FIG. 6A is a perspective view of a stationary seal ring segment employed by
the
mechanical seal of the present invention.
FIG. 6B is an exploded partial cross-sectional view with the spring holder
plate removed
showing the bolts, biasing clip assembly, and spacer elements employed by the
mechanical seal
of the present invention.
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FIG. 6C is an exploded partial cross-sectional view with the spring holder
plate, biasing
clip assemblies and spacing elements removed showing the bolts and springs
employed by the
mechanical seal of the present invention.
FIG. 7 is a perspective view of the mechanical seal assembly of the present
invention.
FIG. 8 is a partial cross-sectional view of the mechanical seal assembly of
FIG. 7
according to the teachings of the present invention.
FIG. 9 is a perspective view of a segment of the gland assembly showing the
gland
chamber formed in an inner surface thereof according to the teachings of the
present invention.
FIG. 10 is perspective view of one embodiment of a fluid insert element
suitable for
mounting in the gland chamber according to the teachings of the present
invention.
FIG. 11 is a cross-sectional view of the fluid insert element of FIG. 10
according to the
teachings of the present invention.
FIG. 12 is a partial cross-sectional view of the mechanical seal assembly of
FIG. 7
showing the mounting another embodiment of the fluid insert element according
to the teachings
of the present invention.
FIG. 13 is a perspective view of another embodiment of the fluid insert
element suitable
for mounting in the gland chamber according to the teachings of the present
invention.
FIG. 14 is a perspective view of the bottom surface of the fluid insert
element of FIG. 13
according to the teachings of the present invention.
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Detailed Description
The present invention provides a mechanical seal assembly employing a gland
assembly
having a gland chamber formed therein for seating a fluid insert element. The
fluid insert
element helps impart movement to or adjusts, changes or varies the trajectory
of at least a portion
of the particulates that are present in a slurry process fluid and which are
in the area or vicinity of
the seal ring components. The invention will be described below relative to
illustrated
embodiments. Those skilled in the art will appreciate that the present
invention may be
implemented in a number of different applications and embodiments and is not
specifically
limited in its application to the particular embodiment depicted herein.
The terms "mechanical seal assembly" and "mechanical seal" as used herein are
intended
to include various types of mechanical fluid sealing systems, including single
or solid seals, split
seals, concentric seals, spiral seals, tandem seals, dual seals, cartridge
seals, gas seals, and other
known mechanical seal and sealing types and configurations.
The term "shaft" is intended to refer to any suitable device in a mechanical
system to
which a mechanical seal can be mounted and includes shafts, rods and other
known devices. The
shafts can move in any selected direction, such as for example in a rotary
direction or in a
reciprocating direction.
The terms "axial" and "axially" as used herein refer to a direction generally
parallel to the
axis of a shaft. The terms "radial" and "radially" as used herein refer to a
direction generally
perpendicular to the axis of a shaft. The terms "fluid" and "fluids" refer to
liquids, gases, and
combinations thereof.
The terms "axially inner" or "axially inboard" as used herein refer to the
portion of the
stationary equipment and a mechanical seal proximate the stationary equipment
employing the
mechanical seal. Conversely, the terms "axially outer" or "axially outboard"
as used herein refer
to the portion of stationary equipment and a seal assembly distal from the
mechanical system.
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The term "radially inner" as used herein refers to the portion of the
mechanical seal
proximate a shaft. Conversely, the term "radially outer" as used herein refers
to the portion of the
mechanical seal distal from a shaft.
The terms "stationary equipment" and/or "static surface" as used herein are
intended to
include any suitable stationary structure housing a shaft or rod to which a
seal having a gland is
secured.
The terms "process medium" and/or "process fluid" as used herein generally
refers to the
medium or fluid being transferred through the stationary equipment. In pump
applications, for
example, the process medium is the fluid being pumped through the pump
housing.
The term "gland" as used herein is intended to include any suitable structure
that enables,
facilitates or assists securing the mechanical seal to the stationary
equipment, while
concomitantly surrounding or housing, at least partially, one or more seal
components. If desired,
the gland can also provide fluid access to the mechanical seal. Those of
ordinary skill will also
recognize that the gland assembly can form part of the mechanical seal
assembly or form part of
the stationary equipment.
The term "slurry" or "slurry process fluid" as used herein is intended to
include a process
or other type of fluid that contains solid particles or particulates. As such,
the slurry can be a
mixture of denser solid material particulate material that is suspended in a
carrier fluid, such as
water. The most common use of slurry is as a means of transporting solids or
separating
minerals, where the carrier fluid is pumped by a device, such as a centrifugal
pump, that employs
the mechanical seal assembly of the present invention. The size of the solid
particles can vary in
size. The particles may settle below a certain transport velocity and the
mixture can behave like a
Newtonian or a non-Newtonian fluid. Depending on the mixture, the slurry can
be abrasive
and/or corrosive. The fluid can be, for example, a Newtonian fluid having or
exhibiting
Newtonian properties, namely, the viscosity only varies as a response to
changes in temperature
or pressure. Specifically, the viscosity of a Newtonian fluid remains constant
independent of the
amount of shear applied thereto for a constant temperature. Thus, Newtonian
fluids have a linear
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relationship between viscosity and shear stress. The Newtonian fluid has the
ability to settle out
the particulates from the carrier fluid relatively easily and quickly. The
Newtonian fluids can
also be referred to as a settling slurry. The particulates in the settling
slurry are typically greater
than or equal to about 100 p.m. The fluid can also be a non-Newtonian fluid
having or exhibiting
non-Newtonian properties, such that when a shear force is applied thereto, the
viscosity of the
non-Newtonian fluid decreases or increases as a function of the type of fluid.
The non-
Newtonian fluid has difficultly settling out particulates, and hence is also
referred to as a non-
settling slurry (e.g., homogenous mixture). In non-settling slurries, the
fluid includes a more
homogenous mixture of the fluid and particulates. The particulates in the non-
settling slurry are
typically less than about 100 lam. The slurry can different types of slurries,
such as a clean slurry.
a light slurry, or a heavy slurry.
FIGS. 1-6C depict a mechanical seal 10 according to the teachings of the
present
invention. The illustrated mechanical seal 10 is preferably concentrically
disposed about a shaft
(not shown) and can be secured to an external wall of stationary equipment by
fasteners, such as
bolts, that seat between the illustrated bolt tabs 14. The mechanical seal 10
constructed in
accordance with the teachings of the present invention provides a fluid-tight
seal, thereby
preventing a process medium, e.g., hydraulic fluid, from escaping the
stationary equipment. The
fluid-tight seal is achieved by a pair of sealing members, illustrated as a
rotary seal ring 20 and a
stationary seal ring 30, that form a seal therebetween. Each of the seal rings
20 and 30 has a pair
of seal ring halves or segments and has a smooth arcuate sealing surface 21,
31, respectively.
The smooth arcuate sealing surface 21, 31 of each seal ring is biased into
sealing contact with the
corresponding sealing surface 21 or 31 of the other seal ring. Preferably, the
seal rings 20, 30 are
split into a pair of segments, respectively, to facilitate installation, as
described below. The
sealing surfaces 21, 31 of the seal rings provide a fluid-tight seal operable
under a wide range of
operating conditions, including a vacuum condition. The rotary seal ring 20 is
mounted within a
holder assembly 110, which is in turn mounted within a gland assembly 40, and
the stationary
seal ring 30 is mounted within the gland assembly 40.
As shown in FIGS. 2A-3B and 5B, the illustrated holder assembly 110 defines a
space
111 for receiving and retaining the rotary seal ring 20. The holder assembly
110 can be split to
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facilitate easy assembly and installation. In one embodiment, the holder
assembly 110 comprises
a pair of arcuate holder segments 112 that mate to form the annular holder
assembly 110. The
holder assembly 110, or each arcuate holder segment 112 if the holder assembly
is split, has a
radially outer surface 116 facing the gland assembly 40 and a first generally
radially inner
surface 124 (in addition to the radial innermost surface 138) for sealing
against the seal ring 20
and defining the space 111 for receiving and retaining the rotary seal ring
20.
A sealing element, such as 0-ring 188, is concentrically disposed about the
rotary seal
ring 20 to seal between the rotary seal ring 20 and the holder assembly 110.
As shown, the 0-
ring 188 is preferably disposed about a radially outer surface 184 of an
axially inner portion of
the rotary seal ring 20 and seals against the radially inner surface 124 of
the holder assembly
110. The radially inner surface 124 of the holder assembly 110 may include a
detent groove 189
for receiving and seating the 0-ring 188 disposed about the rotary seal ring
20 to facilitate
assembly and operation of the mechanical seal and to maintain the rotary seal
ring 20 in an
optimal position.
Other sealing members can be provided to seal the interfaces between different
components of the mechanical seal 10. For example, a flat annular elastomeric
gasket 60 can be
employed to seal the interface between the gland assembly 40 and the
stationary equipment.
Further, a holder gasket 160 can be mounted in a corresponding groove 158 to
seal the holder
segments 112 together if the holder assembly 110 is split. A holder/shaft
elastomeric member,
illustrated as 0-ring 142, sits in a holder groove 140 formed along the inner
surface 138 and
seals between the rotary seal ring holder assembly 110 and the shaft. A
stationary seal ring/gland
elastomeric member, illustrated as 0-ring 202, seals at an interface between
the stationary seal
ring 30 and the gland assembly 40 and provides radially inward pressure on the
stationary seal
ring 30. A gland gasket 76 can seat within a gland gasket groove 70 (FIG. 3A)
so as to form a
seal between the gland halves when assembled together. One skilled in the art
will recognize that
the mechanical seal assembly 10 may have any suitable means for sealing
between different
components.
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In addition, the illustrated split mechanical seal 10 can include an anti-
rotation
mechanism (not shown) such as a pin or a flat surfaced element that extends
axially between the
rotary seal ring 20 and the holder assembly 110 to prevent relative rotary
movement between the
rotary seal ring and the holder assembly 110. Those of ordinary skill will
also recognize that
suitable fasteners, such as bolts, can be employed to secure together the
gland halves and the
holder halves. Certain components of the mechanical seal 10 of the present
invention are similar
to the mechanical seal assemblies described in U.S. Pat. Nos. 5,571,268,
7,708,283 and
10,352,457, the contents of which are herein incorporated by reference.
The illustrated holder assembly 110 for mounting the rotary seal ring 20 is
disposed in a
chamber 24 formed by the gland assembly 40, and spaced radially inward
therefrom. It should be
understood, however, that the holder assembly 110 need not be disposed within
the gland
assembly 40. Rather, the holder assembly 110 can be axially spaced from the
gland assembly 40.
The holder assembly 110 also includes an inwardly stepped surface that forms a
second, axially-
extending face 133. The radially inner surface 124 and the axially extending
face 133 have a
radially inward-extending first wall 132 formed therebetween. As shown, the
inner axially
extending face 133 and the radially innermost axially extending face or holder
inner face 138
define an axially innermost second wall 134 therebetween that serves as the
bottom of a cavity or
seal ring receiving space 111 (FIG. 2B) that seats the rotary seal ring 20.
According to one embodiment, the sealing element or 0-ring 188 for sealing
between the
rotary seal ring 20 and the rotary seal ring holder 110 seats in a groove 189,
such as a detent
groove, formed on the radially inner surface 124 of the holder assembly 110.
The detent groove
189 is sized, located and configured to receive a radially outermost portion
of the 0-ring 188 so
as to position and seat the 0-ring 188 relative to the holder assembly 110
during installation
without compromising performance. The detent groove 189 preferably seats the 0-
ring 188
above the stepped wall 132. Alternatively, the detent groove 189 seats the 0-
ring in another
location between the holder assembly 110 and the rotary seal ring 20. A
significant advantage of
the detent groove 189 and the placement of the groove on the radially inner
surface 124 of the
holder is that it reduces the amount of compression needed to seat the 0-ring
188 in the groove.
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The illustrated rotary sealing ring 20 includes a substantially smooth arcuate
inner surface
172 and an outer surface comprising several surfaces including a first outer
slanted surface 182
that forms a skirt portion, a relatively flat outer surface 184, and an
axially inwardly tapered or
sloped outer surface 186. The rotary seal ring 20 also includes a smooth
arcuate sealing surface
21 disposed at a top of the seal ring 20. A rotary seal ring detent groove 92
is formed on the flat
outer surface 184 adjacent the first slanted surface 182, as best shown in
FIGS. 3B and 5B. The
detent groove 92 formed in the rotary seal ring 20 performs at least two
primary functions: first,
the groove 92 helps to position the rotary seal ring 20 in the correct
location with respect to the
holder assembly 110, and second, the groove 92 allows the rotary seal ring to
be pre-assembled
in the holder assembly 110 by creating a double capture groove (between the
holder detent
groove 189 and the rotary seal ring detent groove 92) that captures the 0-ring
188 therebetween
while concomitantly retaining the rotary seal ring 20 within the holder
assembly 110. The inner
surface 172 of the rotary seal ring may have formed thereon a generally
rectangular notch (not
shown) that mounts over a holder protrusion (not shown) for coupling the
components together.
The inner diameter of the rotary seal ring inner surface 172 is greater than
the diameter of the
shaft to permit mounting thereon. The diameter of the rotary seal segment
outer surface 184 is
equal to or slightly less than the diameter of the axially extending face 133
of the holder
segment, for mounting engagement with the holder assembly 110. The diameter of
the outermost
surface of the rotary seal ring 20 is less than the inner diameter of the
inner surface 124 of the
holder assembly 110. One skilled in the art will readily recognize based on
the teachings herein
that the rotary seal ring 20 may have any suitable configuration for
interfacing with and sealing
against another sealing element, such as the stationary seal ring 30.
As shown in FIGS. 1-3B and 5A. the illustrated mechanical seal 10 also
includes the
gland assembly 40. The illustrated gland assembly 40 includes a pair of
arcuate gland segments
41, 42 that mate to form the annular seal gland assembly 40. The gland
segments 41, 42 can be
configured to engage with each other to facilitate assembly and operation of
the mechanical seal
10. The gland assembly segments 41, 42 can employ an interlock mechanism to
facilitate
engagement of the gland segments. Each of the illustrated gland segments 41,42
has an inner
surface that has a first face 46 disposed at an axial outboard end that has an
angled lead-in
surface 52 and an integrally formed and stepped second face 50 that extends
radially outwardly
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from the first face 46. The first face 46 and the second face 50 form, in
combination, a first
connecting annular wall 48. The stepped second face 50 transitions to a
radially inwardly sloped
surface 56. The gland segment inner surface formed by faces 46, 48, 50, and 56
define the space
24 for receiving the holder assembly 110, as described above. Further, each of
the gland
segments 41, 42 also has integrally formed therewith a pair of screw housings
80, 82. Each of the
screw housings 80, 82 can include a transverse fastener-receiving aperture 84
formed
substantially therethrough. The transverse aperture 84 mounts a screw 90 for
securing together
the gland segments 41, 42. The gland assembly 40 also includes a housing
gasket groove 58
formed alone a bottom inboard surface 59 of the gland assembly 40. The groove
58 seats the flat,
annular elastomeric gasket 60. The gland assembly 40 also includes an axially
outer topmost
surface 62 that has a plurality of spring holes 64 and a plurality of fastener
holes 66 formed
therein. The spring holes 64 mount spring elements 80 and the fastener holes
mount suitable
fasteners, such as the bolts 250.
As shown in FIGS. 2A-3B, 5A, and 6A-6C, and in particular as shown in FIG. 6A,
the
illustrated stationary seal ring 30 can similarly include a pair of arcuate
seal ring segments, each
identical or substantially identical to the other. The illustrated stationary
seal ring segments can
have a substantially smooth arcuate inner surface 32 extending parallel to the
shaft axis and an
opposed outer surface 36. The inner surface 32 has formed along the inner wall
a
circumferentially extending recess or groove 33 that is sized and configured
for receiving a
retaining portion of a biasing clip assembly 210, described in further detail
below, for mounting
and retaining the stationary seal ring 30 to a spring holding plate 230. The
groove 33 can be
continuous or non-continuous. If non-continuous, the groove can be formed as a
series of
recesses that are spaced apart along the inner surface 32. The outer surface
36 of the stationary
seal ring 30 preferably has an axially extending first outer surface 190 that
terminates in a
radially outward extending sloped abutment surface 192. The stationary seal
ring 30 preferably
has an axially outer top surface 194 and an opposed smooth axially inner
arcuate ring sealing
surface 31 disposed at the bottom of the seal ring. The top surface 194 has a
series of recesses or
cut-outs 196 formed along the top surface that are sized and configured for
selectively seating
and/or engaging at least a portion of the biasing clip assembly 210. This
arrangement helps align
and seat the stationary seal ring 30 in the chamber 24, as well as functioning
as a mechanical
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impedance for preventing the stationary seal ring 30 from rotating with the
shaft 12 and the
rotary seal ring 20.
The inner diameter of the stationary seal ring 30 as defined by the inner
surface 32 is
greater than the shaft diameter, and can if desired be greater than the
diameter of the inner
surface 172 of the rotary seal ring 20, thereby allowing relative motion
therebetween. Therefore,
the stationary seal ring 30 remains stationary while the shaft rotates. An
elastomeric sealing
member, e.g., 0-ring 202, provides a radially inward biasing force sufficient
to place the seal
ring segment sealing faces 35 in sealing contact with the other stationary
seal ring segment.
Additionally, the 0-ring 202 forms a fluid-tight and pressure-tight seal
between the inner surface
46 of the gland assembly 40 and the stationary seal ring 30. The 0-ring 202
scats in a first
mounting region 204 defined by the gland first face 46 and the annular wall 48
and the outer
surface 190 of the stationary seal ring 30 when disposed in the loaded
position. In a preferred
embodiment, the abutment 192 of the stationary seal ring 30 forms an angle
relative to the
stationary seal ring outer surface 190 preferably in the range of between
about 30 and about 60 ,
and most preferably about 45 . The stationary seal ring 30 is preferably
composed of a carbon or
ceramic material, such as alumina or silicon carbide and the like.
The biasing assembly of the split mechanical seal 10 of the present invention,
illustrated
as a biasing clip assembly 210, also functions as an axial biasing means by
providing resilient
support for the stationary and rotary seal rings 20, 30 by axially biasing the
seal rings such that
the stationary and rotary sealing surfaces 21 and 31 are disposed in sealing
contact with each
other. As illustrated in FIGS. 2A-3B, the seal rings 20, 30 are floatingly and
non-rigidly
supported in spaced floating relation relative to the rigid walls and faces of
the gland and holder
assemblies 40, 110. This floating and non-rigid support and spaced
relationship permits small
radial and axial floating movements of the rotary seal segments and the
stationary seal segments
with respect to the shaft 12, while still allowing the rotary sealing surface
21 to follow and to be
placed in sealing contact with the smooth arcuate sealing surface 31 of the
stationary seal ring
30. Thus, the rotary and stationary seal ring sealing surfaces 21 and 31 are
self-aligning as a
result of this floating action.
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The mechanical seal 10 of the present invention preferably employs a series of
biasing
clip assemblies 210 that are mounted on the axially outermost end of the gland
assembly 40.
Since the biasing clip assemblies 210 are identical, we need only describe
herein one of the clip
assemblies. The biasing clip assembly 210 preferably employs a pair of
generally C-shaped
spring clips defined as an inner spring clip 216 and an outer spring clip 218.
The inner spring
clip 216 has a first lower end that has a ridge portion 220 that seats within
a recessed portion 242
of the spring holder plate 230. The engagement of the ridge portion 220 of the
inner spring 216
with the recessed portion 242 helps secure the inner spring clip 216 thereto.
The inner spring clip
216 further includes at an opposite end a bent portion 222 that seats on or
can be disposed in
contact with the recessed portion 196 formed in the top surface 194 of the
stationary seal ring 30
to provide an axial biasing force thereto. The bent portion 222 thus functions
as an axial biasing
member for applying an axial biasing force to the seal rings 20, 30. The axial
biasing force as is
known to those of ordinary skill in the art is an inboard directed force that
helps place the seal
faces 21, 31 of the seal rings 20, 30, respectively, in sealing contact with
each other.
The illustrated mechanical seal 10 also includes an axially movable spring
holder plate
230, as shown for example in FIGS. 2A-4B. The illustrated spring holder plate
230 can be
formed from a pair of plate segments 231, 233 that can be connected together.
The spring holder
plate 230 has an annular main body having a top surface 232 having a plurality
of cut-outs or
recesses 234 formed therein that are circumferentially spaced apart along the
circumference of
the main body. The top surface 232 also has formed therein a series of
fastener-receiving
apertures 236 for receiving fasteners, such as for example the bolts 250. The
spring holder plate
230 also includes a bottom surface 238 having a recessed portion 242 formed
adjacent an axially
extending flange portion 240. The recesses 234 and the recessed portion 242
are configured for
seating a portion of the biasing clip assembly 210, such as selected portions
of the inner spring
clip 216. The spring holder plate segments have end faces 244 that are
configured for mating
with the end faces of the other spring holder plate segment. One of the end
faces 244 has a male
type projection or protrusion 246 and the other end face has a female type
hole or surface feature
248. The protrusion 246 is configured to seat within a corresponding hole 248
formed in the
opposed end face 244 of the other spring holder plate segment. Similarly, the
hole 248 is
configured to receive a corresponding protrusion formed on the opposed end
face of the other
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holder plate segment. The protrusions 246 and holes 248 enable the holder
plate segments to be
mechanically coupled together. The spring holder plate 230 is sized and
dimensioned such that
the flange portion 240 seats between the inner surface 46 of the gland
assembly 40 and the outer
surface 190 of the stationary seal ring 30. The spring holder plate 230 when
tightened by the
bolts 250 compresses the springs 86 and engages with the 0-ring 202. The 0-
ring 202 is pushed
by the flange portion 240 past the lead-in surface 52 of the gland assembly 40
and into the
mounting region 204. Simultaneously, the stationary seal ring 20 is axially
pressed towards the
rotary seal ring 20 by the biasing clip assembly 210.
The biasing clip assembly 210 of the mechanical seal 10 of the present
invention includes
an outer spring clip 218 that is adapted to be mounted over the inner spring
clip 216. The outer
spring clip 218 has a main body that includes a generally rounded first end
portion 224 that is
configured to be mounted on and engage the outer surface of the inner spring
clip 216, as best
illustrated in FIGS. 2B, 3B and 6B. The outer spring clip 218 also includes an
opposite end that
has a bent tab portion 228 extending outwardly therefrom. The bent tab portion
228 is configured
to overlay the bent portion 222 of the inner spring clip 216 and to connect to
and engage the
recess 33 formed along the inner surface 32 of the stationary seal ring 30.
The bent tab portion
228 of the outer spring clip 218 retains or mounts the stationary seal ring 30
to the gland
assembly 40 by engaging with the recess 33. By retaining or mounting the
stationary seal ring 30
to the gland assembly 40, the components of the mechanical seal 10 can be pre-
assembled, which
helps facilitate easy installation of the split mechanical seal 10. Those of
ordinary skill in the art
will readily recognize that the inner and outer spring clips 216, 218 can have
any suitable shape
or configuration provided that the clips can engage with the spring plate
holder 230 and the
stationary seal ring 30 so as to apply an axial biasing force to the
stationary seal ring and to the
spring plate holder.
In assembly and during operation, the mechanical seal 10 can be composed of
four
selected halves or segments that have selected seal components that are
preassembled together to
form subassembly units. For example, as shown in FIG. 5A, each gland segment
of the gland
assembly 40 can be preassembled with selected components to form a gland
subassembly unit
260 that includes a corresponding half or segment of the stationary seal ring
30, the spring holder
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plate 230, the 0-ring 202, and a selected number of biasing clip assemblies
210 that correspond
to the number of recesses 234 formed in the top surface 232 of the spring
holder plate 230. The
inner spring clip 216 is mounted on and about the spring holder plate 230 and
then the outer
spring clip 218 is mounted over or on top of the inner spring clip 216. The
bent tab portion 228
of the outer spring clip 218 engages with the recess 33 formed along the inner
surface 32 of the
stationary seal ring 30 and the opposite end of the spring clips engage with
the spring holder
plate 230. The springs 86 are mounted in the spring holes 64 formed in the top
surface 62 of the
gland assembly 40 and the spring holder plate 230 is secured to the top
surface by the bolts 250
when disposed in the corresponding fastener holes 66.
Similarly, as shown for example in FIG. 5B, each holder segment of the holder
assembly
110 can be preassembled with selected seal components to form a holder
subassembly unit 270
that includes a corresponding half or segment of the rotary seal ring 20 and
the 0-ring 188. A
holder spacer element 126 is disposed in the holder space 111. The spacer
element 126 assists
with initially axially positioning selected seal components, such as for
example the 0-ring 188
and for example the rotary seal ring 20, in a selected axial position so as to
prevent accidental
damage to the components. The holder spacer element is removed prior to the
holder assembly
being mounted about the shaft 12. The 0-ring 188 is disposed in the detent
groove 92 formed in
the outer surface 184 of the rotary seal ring 20. When the 0-ring 188 and the
rotary seal ring
segment are disposed within the gland assembly 40, the 0-ring 188 is
positioned to seat within
the detent groove 189 formed in the inner surface 124 of the holder assembly
120. The detent
grooves 92, 189 serve to capture and hold the 0-ring 188 without overly
loading the 0-ring in an
axial or radial direction. The gland and holder subassembly units 260, 270 can
include other
sealing elements as well, including for example, the holder gasket 160, the
gland gaskets 60 and
76, and other 0-rings and sealing elements, such as the 0-ring 142. The
sealing elements are also
split so as to fit in the subassembly units.
When assembling together the holder and gland subassembly units, the sealing
elements,
such as for example the 0-rings 188, 202, can become pinched when the 0-rings
are moved from
the unloaded position to the loaded position. For example, as the 0-rings are
compressed
radially, they expand circumferentially with the ends of the 0-ring segments
protruding,
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potentially buckling when joined, thereby causing pinching by metal or seal
face parts at the
location of the split. In order to prevent this from occurring, the present
invention provides for a
selected assemblage of components that forms a loading assembly that does not
prematurely load
the 0-rings 188, 202 prior to assembly of the subassembly units about the
shaft 12, thus
preventing the 0-rings 188, 202 from extruding past the end faces of the
holder and gland
segments.
With regard to the holder subassembly units 270, each of the 0-ring segments
188 are
concentrically disposed about the rotary seal ring segments 20 and are
preferably disposed in
contact with the rotary seal ring outer surfaces 182, 184 and the rotary seal
ring detent groove 92
to form the rotary seal ring pre-assembly. The 0-ring 188 and the rotary seal
ring 20 arc mounted
in the holder assembly 110 such that the 0-ring 188 seats within the detent
grooves 189, 92
formed in the surfaces 124, 184. This prevents, reduces or minimizes premature
and unwanted
loading of the 0-ring 188 when the holder subassembly units 270 are assembled
together. As
such, the end regions of the 0-ring segments do not extrude past the end faces
of the holder and
gland segments. The holder pre-assembly units 270, 270 are then disposed about
the shaft 12. A
coupling mechanism, such as a drive flat, can be employed to rotationally
couple the rotary seal
ring 20 to the holder assembly 110 for relative rotation therewith. The
coupling mechanism can
be disposed on either the holder assembly or the rotary seal ring, and in a
preferred embodiment,
is disposed on both the rotary and stationary seal rings. The detent groove
189 of the holder
assembly 110 and the detent groove 92 of the rotary seal ring 20 receive and
retain the 0-ring
188 in an optimal position. The 0-ring 188 provides an inward radial force
sufficient to place the
axial seal faces 25 of the rotary seal ring segments in sealing contact with
each other. The holder
segments are then secured together by tightening the screws 170 that are
positively maintained in
the fastener-receiving apertures 164. The rotary seal ring segments are spaced
from the inner
surface 124 of the holder assembly and are non-rigidly supported therein by
the 0-ring 188,
thereby permitting small radial and axial floating movements of the rotary
seal ring 20. When
disposed within the detent grooves, the 0-ring 188 is disposed in the unloaded
position.
With regard to the gland pre-assembly unit 260, the 0-ring 202 is disposed
about the
stationary seal ring 30 and then disposed adjacent the lead-in surface 52
formed along the inner
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surface of the gland assembly 40. The springs 86 are mounted within the
corresponding spring
holes 64 formed in the top surface 62 of the gland assembly 40. The spring
holder plate 230 is
secured to the gland assembly top surface 62 by partially tightening the bolts
250 in the fastener
holes 66. The spring holder plate 230, the springs 86 and the bolts 250 can
form the loading
assembly. The multiple biasing inner clips 216 are mounted along the perimeter
or
circumferential edge of the top surface 61 of the gland assembly. The ridge
portion 220 of the
first end of the inner spring clip 216 is mounted in the recessed portion 242
formed in the bottom
surface 238 of the spring holder plate 230. The outer spring clip 218 when
mounted on the inner
spring clip 216 has the bent tab portion 228 that has an edge or tip that
seats in the groove 33
formed in the inner surface 32 of the stationary seal ring 30. The 0-ring 202
is captured between
the lead-in surface 52 (FIG. 3B) and the outer surface 190 of the stationary
seal ring 30.
As shown in FIGS. 2A and 2B, the gland subassembly unit 260 disposes the 0-
ring 202
into a disengaged and unloaded position and the holder subassembly unit 270
disposes the 0-ring
188 in the detent grooves 188, 92, thus also placing the 0-ring 188 in the
disengaged unloaded
position. As such, the 0-rings 188, 202 do not extrude past the seal faces of
the holder and gland
segments. Once fully assembled, the operator can move the 0-rings 188 and 202
into an engaged
and loaded position by axially moving the spring holder plate 230 in an
inboard direction, as
shown in FIGS. 3A and 3B. For example, the operator can selectively tighten
the bolts 250 with
a suitable tool, such as a wrench. When tightened, the bolts 250 serve to move
the spring holder
plate 230 in the axial inboard direction against the bias of the springs 86.
The bottom surface of
the flange portion 240 contacts the 0-ring 202 and pushes the 0-ring 202 in
the axial inboard
direction past the angled lead-in surface 52 and into the space 204. The 0-
ring 202 is hence
squeezed (e.g., loaded) into the region 204 by radial compression and the 0-
ring is disposed in
sealing contact with the outer surface 190 of the stationary seal ring 30 and
the inner face or
surface 46 of the gland assembly 40. The 0-ring 202 is thus placed in the
engaged and loaded
position. Further, since the stationary seal ring 30 is coupled to the spring
holder plate 230 by the
biasing clip assembly 210, the movement of the spring holder plate 230 in the
axial direction
serves to push or move the stationary seal ring 30 in the axial inboard
direction. The stationary
seal ring 30 contacts the rotary seal ring 20 via the seal faces 21, 31, and
hence pushes the rotary
seal ring 20 in the axial inboard direction. The axial movement of the rotary
seal ring 20 pushes
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the 0-ring 188 out of the detent groove 189 formed in the inner surface 124 of
the holder
assembly 110. When moved out of the detent groove 189, the 0-ring is squeezed
(e.g., loaded)
between the inner surface 124 of the holder assembly 110 and the detent groove
92 of the outer
surface 184 of the rotary seal ring 20. The 0-ring 188 thus seats within the
detent groove 92
when in the loaded and unloaded positions. The detent grooves 189 and 92
preferably have a
curved cross-section and are discrete grooves that are sized and configured
for seating the 0-ring
188.
The illustrated loading assembly can thus be employed to axially move the 0-
rings 202,
188 into the engaged and loaded position where they are radially compressed.
The 0-rings are
compressed after the gland and holder subassembly units have been assembled
and secured
around the shaft 12 and to the stationary equipment. The loading assembly of
the present
invention avoids having the 0-rings extrude past the end faces prior to
assembly where they can
be pinched when the subassembly units are secured together. Since the gland
and holder surfaces
defining the regions mounting the 0-rings 202, 188 are in contact with each
other prior to the 0-
ring being radially compressed in the sealing location, there is no protruding
end of the 0-ring
segments with the potential resulting misalignment of the sealing elements.
The spring holder plate 230 further includes segments 231, 233 that are
secured together
using male and female types mechanical connections. The spring holder plate
230, prior to being
tightened by the operator, serves to hold the rotary and stationary 0-rings
188, 202 in a free state
or unloaded position during the securing of the gland and holder subassembly
units 260. 270
around the shaft 12. The preassembled subassembly units 260, 270 allow for
sequenced
installation of the units. Specifically, the holder subassembly units 270
(e.g., rotary subassembly
units) are secured to the shaft 12 and then the gland subassembly units 260
(e.g., stationary
subassembly units) are secured around the rotary components and to the
stationary equipment.
The axial movement of the spring holder plate 230 via the bolts 250 pushes the
seal faces 21, 31
and the rotary and stationary 0-rings 188, 202 into their operating locations.
As such, a single
element can be used to displace the 0-rings 188, 202 from a radially
uncompressed state (e.g.,
unloaded position) to a compressed energized state (e.g., loaded position).
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Another embodiment of the mechanical seal assembly of the present invention is
shown
for example in FIGS. 7- 14. Like reference numerals indicate like or similar
parts throughout the
various views. The mechanical seal assembly 300 forms a no-flush or zero-flush
mechanical seal
assembly since it is not necessary to introduce an external fluid, such as a
flushing or barrier
fluid, into the interior of the seal in order to flush particulates from the
seal faces of the seal
rings. More specifically, the illustrated mechanical seal assembly 300 of the
present invention is
directed to a split mechanical seal assembly that employs a gland assembly
having a gland
chamber formed in an inner surface that is sized and configured for seating
one or more fluid
insert elements or components. The fluid insert component, when mounted within
the gland
chamber, creates an expanded fluid volume of space that promotes circulation
of the slurry
process fluid by the rotating elements of the seal. The illustrated mechanical
seal assembly 300 is
preferably concentrically disposed about a shaft 12 and can be secured to an
external wall of
stationary equipment by fasteners, such as bolts, that seat between the
illustrated bolt tabs 14 or
gland land areas 370. The mechanical seal assembly 300 constructed in
accordance with the
teachings of the present invention provides a fluid-tight seal, thereby
preventing a slurry process
fluid from escaping the stationary equipment. The fluid-tight seal is achieved
by a pair of sealing
members, illustrated as a rotary seal ring 320 and a stationary seal ring 330,
that form a seal
therebetween. Each of the seal rings 20 and 30 has a pair of arcuate seal ring
halves or segments
and has a smooth arcuate sealing face or surface 324 and 334, respectively.
The seal ring
segments can be identical or substantially similar to the other. The smooth
arcuate sealing
surface 324, 334 of each seal ring is biased into sealing contact with the
corresponding sealing
surface of the other seal ring by the biasing clip assembly 210 to form a
sealing interface. The
sealing surfaces 324 and 334 of the seal rings provide a fluid-tight seal
operable under a wide
range of operating conditions, including a vacuum condition. The sealing
surfaces 324 and 334
of each seal ring are preferably the same size and shape so as to form a line-
to-line seal face or
interface. Specifically, with reference to the seal surface 334 of the
stationary seal ring, the
illustrated seal surface 334 has a terminal end surface forming a planar
surface in a single plane.
The sealing surface 334 extends from the inner surface 332 of the terminal end
to the outer
surface of the terminal end. The sealing surface 324 of the stationary seal
ring 320 is formed in a
similar manner. As such, the sealing surfaces 324, 334 have the same size and
shape, fully
overlap, and are aligned so as to form the fluid-tight seal. The rotary seal
ring 320 is mounted
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within a holder chamber of a holder assembly 380, which is in turn mounted
within a gland
mounting region of a gland assembly 340. The stationary seal ring 330 is also
mounted within
the gland mounting region.
The stationary seal ring 330 can have a substantially smooth arcuate inner
surface 332
extending parallel to a longitudinal axis of the shaft 12 and an opposed outer
surface. The inner
surface 332 has formed along the inner wall a circumferentially extending
recess or groove 333
that is sized and configured for receiving a retaining portion of a biasing
clip assembly 210,
described in further detail below, for mounting and retaining the stationary
seal ring 330 to a
spring holding plate 230. The groove 333 can be continuous or non-continuous.
If non-
continuous, the groove 333 can be formed as a series of recesses that are
spaced apart along the
inner surface 332.
The inner diameter of the stationary seal ring 330 as defined by the inner
surface 332 is
greater than the shaft diameter, thereby allowing relative motion
therebetween. Therefore, the
stationary seal ring 330 remains stationary while the shaft rotates. An
elastomeric sealing
member, e.g., 0-ring 202, provides a radially inward biasing force sufficient
to place the axial
sealing faces of the seal ring segments in sealing contact with the other
stationary seal ring
segment. Additionally, the 0-ring 202 forms a fluid-tight and pressure-tight
seal between the
inner surface 374 of the gland assembly 340 and the stationary seal ring 330.
The stationary seal
ring 330 is preferably composed of a carbon or ceramic material, such as
alumina or silicon
carbide and the like.
The illustrated gland assembly 340 has a main body 342 that is coupled to the
stationary
equipment through known fastening mechanisms and techniques. As shown for
example in
FIGS. 1, 7-9, and 12, the gland assembly 340 can employ bolt tabs 18 that can
be
circumferentially arranged about the gland main body in order to accommodate
fasteners, such as
bolts. In the current embodiment, the gland main body 342 includes fastener
channels 372 that
are formed in gland land areas 370. According to one embodiment, the fastener
channels 370
help define the land areas 370 and the fastener housings 80, 82 of the gland
assembly 340. The
fastener channels 372 are sized and configured to accommodate a fastener for
securing the gland
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assembly 340 to the stationary equipment. The main body 342 of the gland
assembly has an
inner surface 374 and an outer surface 376 that includes a radially outer
first annular portion 344
and a radially inwardly stepped second annular portion 346. The inner surface
376 of the gland
assembly has one or more gland chambers 360 formed therein. The gland chamber
360 can be
formed so as to extend along the entire usable circumference of the inner
surface 374 of the main
body 342 or can be formed into separate discrete gland chambers 360 therein,
each of which
extends along only a portion of the circumference of the inner surface 374.
According to one
embodiment, multiple gland chambers 360 can be formed in the inner surface 374
and, in total,
can extend along an arc portion of the inner circumference defined by the
inner surface 374
measuring between about 65 degrees and about 90 degrees of the inner
circumferential surface,
and preferably extends between about 75 degrees and about 80 degrees of the
inner
circumferential surface. The gland chamber 360 has a floor portion 362 and a
set of walls 364
that define the gland chamber 360. The inner surface 374 of the gland assembly
340 and the
stationary equipment forms a space 308 (e.g., gland mounting region) that
seats the other
components of the mechanical seal assembly and which is sized to accommodate
the slurry
process fluid. The floor 362 of the gland chamber 360 can have a shape and
configuration that is
complementary to the shape of the top surface of the fluid insert element 400,
430.
The main body 342 of the gland assembly 340 can have multiple optional
radially
extending ports formed therein. According to one embodiment, the main body 342
has a barrier
or flushing fluid port 352 formed in the first annular portion 344. The
flushing fluid port 352
extends from the outer surface 376 of the main body to the floor portion 362
of the gland
chamber 360. The flushing fluid port 352 can be configured to connect to a
fluid conduit, such as
an external piping system, for introducing a flushing fluid, such as water,
into the inner space
308 of the mechanical seal assembly 300. The flushing fluid can typically be
used to flush or
move particulates that are present in the slurry process fluid away from the
seal faces 324, 334.
The gland assembly 340 can also optionally include a clean-in-place (CIP)
fluid port 354 for
allowing access by a user to the inner space 308 of the mechanical seal
assembly 300. According
to one embodiment, the CIP fluid port 354 is formed in the stepped annular
portion 346 of the
gland main body 342. The CIP fluid port 354 extends from the outer surface 376
of the gland
assembly 340 to the inner surface 374. The CIP fluid port 354 is thus disposed
in direct fluid
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communication with the inner space 308. The CIP fluid port can be configured
to be coupled to a
fluid conduit, such as a piping system, to introduce a clean out fluid, such
as water, to the inner
space 308. The clean out fluid can be used to clean out the space 308 of the
particulates in the
process fluid by moving the particulates away from the seal interface. The
gland assembly 340
can also include an optional mechanical port 348 that is formed in the first
annular portion and
which also extends from the outer surface 376 of the gland assembly to the
inner surface or floor
portion 362 of the gland chamber 360. The mechanical port 348 can be sized and
configured for
seating a fastener 350 that can be used to secure a fluid insert element 400,
430 in the gland
chamber 360.
The illustrated mechanical seal assembly 300 can also include a holder
assembly 380 that
defines a space for receiving and retaining the rotary seal ring 320. The
holder assembly 380 can
be split to facilitate easy assembly and installation. In one embodiment, the
holder assembly 380
comprises a pair of arcuate holder segments that mate together to form the
annular holder
assembly 380. The holder assembly 380, or each arcuate holder segment if the
holder assembly
is split, has a main body having a radially outer surface 382 facing the gland
assembly 340 and a
first generally radially inner surface 384 (in addition to the radial
innermost surface 386) for
sealing against the rotary seal ring 320 and defining the space for receiving
and retaining the
rotary seal ring 320.
A sealing element, such as 0-ring 188, is concentrically disposed about the
rotary seal
ring 20 to seal between the rotary seal ring 20 and the holder assembly 110.
As shown, the 0-
ring 188 is preferably disposed about a radially outer surface of an axially
inner portion of the
rotary seal ring 320 and seals against the radially inner surface 384 of the
holder assembly 380.
The radially inner surface 384 of the holder assembly 380 may optionally
include a detent
groove 189 for receiving and seating the 0-ring 188 disposed about the rotary
seal ring 320 to
facilitate assembly and operation of the mechanical seal and to maintain the
rotary seal ring 320
in an optimal position.
Other sealing members can be provided to seal the interfaces between different
components of the mechanical seal assembly 300. For example, a flat annular
elastomeric gasket
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60 can be employed to seal the interface between the gland assembly 340 and
the stationary
equipment. Further, a holder gasket 160 can be mounted in a corresponding
groove to seal the
holder segments together if the holder assembly 380 is split. A holder/shaft
elastomeric member,
illustrated as 0-ring 142, sits in a holder groove formed along the innermost
surface 386 and
seals between the holder assembly 380 and the shaft 12. A stationary seal
ring/gland elastomeric
member, illustrated as 0-ring 202, seals at an interface between the
stationary seal ring 330 and
the gland assembly 340 and provides radially inward pressure on the stationary
seal ring 330. A
gland gasket 76 can seat within a gland gasket groove 70 (FIG. 9) so as to
form a seal between
the gland halves when assembled together. One skilled in the art will
recognize that the
mechanical seal assembly 300 may have any suitable means for sealing between
different
components.
In addition, the illustrated split mechanical seal 300 can include an anti-
rotation
mechanism (not shown) such as a pin or a flat surfaced element that extends
axially between the
rotary seal ring 320 and the holder assembly 380 to prevent relative rotary
movement between
the rotary seal ring 330 and the holder assembly 380. Those of ordinary skill
will also recognize
that suitable fasteners, such as bolts, can be employed to secure together the
gland halves and the
holder halves. Certain components of the mechanical seal 300 of the present
invention are
similar to the mechanical seal assemblies described in U.S. Pat. Nos.
5,571,268, 7,708,283 and
10,352,457, the contents of which are herein incorporated by reference.
According to one embodiment, one or more of the illustrated seal rings 320,
330, the
holder assembly 380, and the gland assembly 340 can include a detent groove
similar to the
detent grooves previously described in connection with the mechanical seal
assembly 10. The
detent grooves operate and function in the same or similar manner.
In the mechanical seal assembly 300 of the present invention, an axial
outboard biasing
clip assembly 210 can be employed to generate and apply an axially inwardly
extending biasing
force to the stationary seal ring 330, thus placing the seal faces 324, 334 of
the rotary and
stationary seal rings in sealing contact with each other. The illustrated
biasing clip assembly 210
also functions as an axial biasing mechanism by providing resilient support
for the stationary and
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rotary seal rings 320, 330 by axially biasing the seal rings together, such
that the stationary and
rotary sealing surfaces 334 and 324 are disposed in sealing contact with each
other to form the
sealing interface. The seal rings 320, 330 are floatingly and non-rigidly
supported in spaced
floating relation relative to the rigid walls and faces of the gland assembly
340 and the holder
assembly 380. This floating and non-rigid support and spaced relationship
permits radial and
axial floating movements of the rotary seal segments and the stationary seal
segments with
respect to the shaft 12, while still allowing the rotary sealing surface 324
to follow and to be
placed in sealing contact with the smooth arcuate sealing surface 334 of the
stationary seal ring
330. Thus, the rotary and stationary seal ring sealing surfaces are self-
aligning as a result of this
floating action.
The mechanical seal assembly 300 of the present invention can employ a series
of biasing
clip assemblies 210 that are mounted on the axially outermost end of the gland
assembly 340.
Since the biasing clip assemblies 210 are identical, only one clip assembly is
described herein.
The biasing clip assembly 210 can employ an inner generally C-shaped spring
clip, defined as an
inner spring clip 216, and an outer spring clip 390. The inner spring clip 216
has a first lower end
220 that is configured to seat between the spring holder plate 230 and the top
or outer surface of
the gland assembly 340 when coupled together to secure the inner spring clip
216 therebetween.
According to one embodiment, the end surface of the stationary seal ring 330
can be relatively
flat. According to another embodiment, the end surface of the stationary seal
ring 330 can be flat
and annular or the end surface can have recessed portions formed therein, such
as the recessed
portions 196. Although the inner spring clip is described as seating within
the recess, the present
invention also contemplates that the inner spring clip seats against the flat
end surface.
Specifically, the inner spring clip 216 can include a bent portion 222 that
seats on or can be
disposed in contact with the top surface of the stationary seal ring 330 to
provide an axial biasing
force thereto. The bent portion 222 thus functions as an axial biasing member
for applying an
axial biasing force to the seal rings 320, 330. The axial biasing force as is
known to those of
ordinary skill in the art is an inboard directed force that helps place the
seal faces 324, 334 of the
seal rings 320, 330, respectively, in sealing contact with each other.
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The illustrated mechanical seal assembly 300 also includes an axially movable
spring
holder plate 230. The illustrated spring holder plate 230 can be formed from a
pair of plate
segments that can be connected together. The spring holder plate 230 has an
annular main body
having a top surface 232 that can optionally include a plurality of cut-outs
or recesses 234
formed therein that are circumferentially spaced apart along the circumference
of the main body.
The top surface 232 also has formed therein a series of fastener-receiving
apertures 236 for
receiving fasteners, such as for example the bolts 250. The spring holder
plate 230 also includes
a bottom surface 238 having a recessed portion 242 formed adjacent an axially
extending flange
portion 240. The recesses 234 and the recessed portion 242 are configured for
seating a portion
of the biasing clip assembly 210, such as selected portions of the inner
spring clip 216. The
spring holder plate segments have end faces 244 that arc configured for mating
with the end
faces of the other spring holder plate segment. The spring holder plate 230 is
sized and
dimensioned such that the flange portion 240 seats between the inner surface
374 of the gland
assembly 340 and the outer surface of the stationary seal ring 330. The spring
holder plate 230
when tightened by the bolts 250 compresses the plate 230 and engages with the
0-ring 202. The
0-ring 202 is pushed by the flange portion past the lead-in surface of the
gland assembly 340 and
into the mounting region 204. Simultaneously, the stationary seal ring 330 is
axially pressed
towards the rotary seal ring 20 by the biasing clip assembly 210.
The biasing clip assembly 210 of the mechanical seal 10 of the present
invention also
includes an outer spring clip 390 that is adapted to be operatively coupled to
the inner spring clip
216 and which functions as a retaining portion. Specifically, outer spring
clip 390 has a main
body that includes a generally rounded or coiled first end portion 392 that is
configured to be
mounted within and engage the bent portion 222 of the inner spring 216. The
engagement of the
coiled portion 392 and the bent portion 222 serves to retain and seat the
outer spring clip 390.
The main body of the outer spring clip 390 also includes a bent tab portion
394 that is disposed
opposite the coiled portion 392. The bent tab portion 394 is configured to
overlie the terminal
end region of the stationary seal ring 330 and to engage and seat within the
groove 333 formed in
the inner surface 332 thereof. The bent tab portion 394 of the outer spring
clip 390 retains or
mounts the stationary seal ring 330 to the gland assembly 340 by engaging with
the recess 333.
By retaining or mounting the stationary seal ring 330 to the gland assembly
340, the components
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of the mechanical seal assembly 300 can he pre-assembled, which helps
facilitate easy
installation of the split mechanical seal assembly 300. Those of ordinary
skill in the art will
readily recognize that the inner and outer spring clips 216, 390 can have any
suitable shape or
configuration provided that the clips can engage with the spring plate holder
230 and the
stationary seal ring 330 so as to apply an axial biasing force to the
stationary seal ring and to the
spring plate holder.
With reference to FIGS. 7-11, the mechanical seal assembly 300 includes the
fluid insert
element 400 that is sized and configured to seat within the gland chamber 360
that is formed in
the inner surface 374 of the gland assembly 340. The fluid insert element 400
can have any
selected size, shape or configuration. When seated within the gland chamber
360, the fluid insert
element 400 has an exposed surface that faces and is exposed to the slurry
process fluid in the
space 308. The exposed surface of the fluid insert element 400 can have any
selected shape, and
preferably has a non-planar shape that includes one or more curved, sloped or
stepped surface
features formed therein that are sufficient for promoting movement of the
process fluid and any
particulates contained therein back towards the stationary equipment and away
from the seal
interface formed by the seal faces 324, 334. According to one embodiment, the
illustrated fluid
insert element 400 has a main body 402 that has a top surface 404 and a series
of side walls or
surfaces 406. The main body 402 also has a bottom surface 408 that forms the
exposed surface
that interfaces with or is exposed to the slurry process fluid. The top
surface 404 of the main
body can have any selected shape or configuration, and according to one
embodiment, includes a
stepped tower portion 410. The stepped tower portion 410 can include a top
portion 412 and
connected side walls 414. The side walls 414 can be solid and hence closed or
one more of the
side walls 414 can have a fluid opening 416 formed therein. The fluid opening
416 can have any
selected shape or configuration. The top portion 412 of the tower portion 410
can also include an
opening 418 that can be aligned with the flushing fluid port 352. Likewise,
the main body
portion can also include a fluid opening 420 formed in the top surface 404
that is aligned with
the opening 418 and the fluid port 352. Further, the top surface 404 can have
an opening 422 that
is aligned with the mechanical port 348 for seating and retaining a portion of
the fastener 350.
The adjacent side wall 406B can have a side opening 424 formed therein. In
order to make the
fluid insert element 400 reversible in nature, the opening 422 can also be
formed in the opposed
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ends of the top surface 404 and the opposed side wall 406A can also have the
side opening 424
formed therein. The illustrated bottom surface 408 can be shaped in any
selected manner.
According to one embodiment, the bottom surface 408 has a curved shape that
curves or extends
in a lateral direction between the side walls 406A and 406B. According to
another embodiment,
the bottom surface 408 can have a curved shape that extends in a medial (e.g.,
front-back)
direction between the side walls 406C and 406D. According to yet another
embodiment, the
bottom surface 408 can be curved in both the lateral and medial directions.
According to another embodiment, the fluid insert element can have a different
shape and
configuration for enhancing or promoting the movement of particulates in the
slurry process
fluid away from the seal faces of the seal rings 320, 330. As shown for
example in FIGS. 12-14,
the illustrated fluid insert element 430 has a main body 432 that has a top
surface 434 and a
series of side walls or surface 436. The main body 432 also has a bottom
surface 438 that forms
the exposed surface that interfaces with or is exposed to the slurry process
fluid. The top surface
434 can have any selected shape or configuration, and according to one
embodiment, includes a
stepped tower portion 440. The stepped tower portion 440 can include a top
portion 442 and
connected side walls 444. The side walls 444 can be solid and hence closed or
one more of the
side walls 444 can have a fluid opening 446 formed therein. The fluid opening
446 can have any
selected size, shape or configuration. The top portion 442 can also include an
opening that can be
aligned with the flushing fluid port 352. Likewise, the main body portion can
include a fluid
opening 450 formed in the top surface 434 that is aligned with the opening in
the tower portion
and the fluid port 352. Further, the top surface 434 of the main body 432 can
have an opening
452 formed therein that is aligned with the mechanical port 348 for seating
and retaining a
portion of the fastener 350. The adjacent side wall can have a side opening
formed therein. As
shown for example in the illustrated embodiment, the side walls 436A and 436B
can each have
the opening 454 formed therein. In order to make the fluid insert element 430
reversible in
nature, the opening 452 can also be formed in the opposed ends of the top
surface 434 and the
opposed side walls 436A and 436B can also have the side opening 454 formed
therein. The
illustrated bottom surface 438 can be shaped in any selected manner. According
to one
embodiment, the bottom surface 438 has a muti-contoured shape that includes
both curved and
sloped regions. For example, the bottom surface 438 can be sloped in the
medial direction (e.g.,
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between side walls 436C and 436D). The sloped surface can include sloped
opposed end
portions 462 and an intermediate sloped portion 464. The sloped end portions
462 can be sloped
at angles that are less than or shallower than the slope angle of the
intermediate sloped region
464. Th bottom surface 438 also includes a curved region 468 that extends
laterally between the
side walls 436A and 436B.
When assembled, the fluid insert element 400, 430 can be inserted into the
gland chamber
360 and the fluid openings are aligned with the mechanical port 348 and the
flushing fluid port
352. The space 308 formed between the outer surfaces of the seal rings 320,
330 and the inner
surface 374 of the gland assembly and the bottom surface of the fluid insert
component forms an
annular chamber or space 308 that houses the slurry process fluid. The slurry
process fluid to be
sealed is housed and flows within this space 308. The movement of the rotary
components of the
mechanical seal assembly 300, such as the holder assembly 380 and the rotary
seal ring 330,
forms turbulence within the slurry process fluid, which in turn promotes
movement of the
process fluid within the space 308. It is during this movement that the
particles in the sluiTy
process fluid build up at the seal interface. According to the another
embodiment, the holder
assembly 380 can have one or more surface features formed on the outer surface
in the form of
pumping vanes to further promote movement of the slurry process fluid. The
particulates present
within the slurry process fluid can accumulate during use at the seal faces
324, 334 of the seal
rings 320, 330, which over time can damage the seal faces. In an effort to
promote movement of
the particulates away from the seal faces 324 and 334 and to protect the seal
components, the
gland chamber 360 seats the fluid insert component that has a specially
configured bottom
surface that promotes movement of the particulates away from the seal faces by
altering the flow
dynamics within the space 308. Specifically, the gland chamber 360 can have a
depth or height
that is sufficient to accommodate the fluid insert element, while also
increasing the space formed
between the bottom surface of the fluid insert element and the outer surface
of the holder
assembly 380. This arrangement of components provides or forms a larger flow
area or volume
within the space 308. The substantially increased space or volume allows the
fluid insert element
to move the particles away from the seal interface, thereby preventing
particle build-up and
impaction on the seal faces 324 and 334. The combination of the gland chamber
360 and the
fluid insert elements 400, 430 provides larger flow area volumes within the
seal, thus eliminating
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the potential impact of contaminant particles on the seal faces. As the slurry
is pumped or moved
during use, the bottom surface of the fluid insert element promotes movement
of the particulates
away from the seal faces. More specifically, the shape of the bottom surface
408, 438 promotes
movement of the particulates away from the seal faces, as shown by the arrow
470 in FIGS. 8
and 12. The arrows 470 are indicative of the ejection path and associated
trajectories of the fluid
particles.
The advantages of employing the fluid insert element are numerous. The fluid
insert
element 400, 430 helps provide for additional circulation of the slurry
process fluid around the
seal faces. The fluid insert element also helps increase the dissipation of
frictional heat that can
be generated at the seal faces. Further, the motion of the slurry process
fluid created by the fluid
insert element during use helps prevent the stationary 0-rings from becoming
clogged with the
particulate matter. Still further, since fluid flow is induced by the rotating
parts of the mechanical
seal assembly and the fluid insert element promotes movement of the particles
away from the
seal faces, there is no need to provide or employ an external flushing fluid.
As such, there is no
need to provide any associated fluid supplying structure or power needed for
flushing the
mechanical seal assembly 300. Additional surface features can be added to
selected rotating
components (e.g. the outside diameter of dynamic/rotating seal face) to
increase fluid flow
velocity. Another advantage of the mechanical seal assembly 300 of the present
invention is that
the seal can be configured to use the available space 308 in the gland
assembly to form the gland
chamber 360 so as to optimize fluid flow and the flow characteristics of the
slurry process fluid.
By way of a simple example, in a conventional 3.5 inch mechanical seal, the
normal
chamber area between the inner surface of the gland or housing and holder
assembly can be
about 8.50 cubic inches. According to the present invention, the combination
of the gland
chamber 360 and the seated fluid insert element 400, 430, as shown and
described herein, can
increase the volume area to about 10.8 cubic inches. As such, the mechanical
seal assembly 300
of the present invention employs a fluid insert element that adds between
about 15% and about
30% additional volume in the space 308.
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The illustrated fluid insert elements 400, 430 have a selected configuration
for forming
multiple different flow paths, including a return flow path for particulates
in the slurry process
fluid. The geometry of the fluid insert elements provides a pressure
differential due to the flow
regime around the rotating shaft 12. The pressure difference causes fluid flow
that imparts
movement on the slurry particles. The geometry of the bottom surface of the
fluid insert elements
400, 430 also causes ejection of the particles away from the seal face area
and imparts
momentum on the particles so that they can be ejected away from seal faces
back to the process
fluid reservoir (e.g., within the stationary equipment). The present
configuration of the fluid
insert element also eliminates (i.e. flush-less or zero-flush system) or
reduces flush flow rate
requirements. One of ordinary skill in the art will readily recognize that the
fluid insert element
can have any selected shape or configuration provided that the bottom surface
of the element is
configured to impart flow to the process fluid and to promote movement of the
particulates away
from the seal faces.
The fluid insert element 400, 430 can be formed by employing conventional
additive
manufacturing techniques. Further, forming the component as a separate
component eliminates
the need to machine complex patterns and shapes into the inner surface of the
gland assembly.
The fluid insert element 400, 430 can also impart fluid flow independent of
direction of rotation
of the shaft (e.g., bi-directional operation). Further, the symmetrical
configuration of the fluid
insert element allows for bi-directional operation.
The fluid insert element can be formed from any suitable material, including
for example
polyurethane, plastic, rubber, EPDM, H-NBR, and the like. The material can be
selected so as to
provide improved wear characteristics relative to conventional metal materials
(i.e. current
erosion of stainless steel glands).
It will thus be seen that the invention efficiently attains the objects set
forth above, among
those made apparent from the preceding description. Since certain changes may
be made in the
above constructions without departing from the scope of the invention, it is
intended that all
matter contained in the above description or shown in the accompanying
drawings be interpreted
as illustrative and not in a limiting sense.
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It is also to be understood that the following claims are to cover all generic
and specific
features of the invention described herein, and all statements of the scope of
the invention which,
as a matter of language, might be said to fall therebetween.
Having described the invention, what is claimed as new and desired to be
secured by
Letters Patent is:
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