Note: Descriptions are shown in the official language in which they were submitted.
8EAL 8AV~R 8P}:CIFICATIOM
This device is a filter which is installed within a
centrifugal pump between the impeller and the mechanical seal
or packing. Its purpose is to protect the mechanical seal
or packing from contaminants in the liquid being pumped.
Generally speaking, the present invention provides
a seal cavity protector for use with rotary fluid equipment
a seal cavity of which is defined by a rotary shaft, a shaft
housing and seal means engaging the shaft, the protector
comprising: an annular generally cup-shaped element adapted
to pass the shaft therethrough and to be secured to the
housing at the entrance to the seal cavity, the element
including a plurality of circumferentially spaced apart,
first and second vent passages extending through the wall
thereof; and an annular inwardly extending flange defining
an opening through which the shaft can pass and including a
plurality of circumferentially spaced apart third vent
passages extending therethrough.
In the past, filtration, cooling systems, and
flushing systems have utilized various forms of pumping
devices which rotate within the pump housing, or a special
housing, to direct the flow of the fluid around the seal.
Generally these systems do not remove contaminants, but only
re-circulate fluids for cooling and lubrication.
The existing technology, utilizes either special
pumping ring-seals or special housings, which cannot be
easily retro-fitted into existing production pumps.
The invention described herein is designed for easy
retro-fit into existing centrifugal pumps, turbines and other
fluid-flow machines. The present invention occupies very
little axial space and does not a~fect normal maintenance
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procedures. The present invention can be used tc pro-tec-t
any make of mechanical seal or pack~ng from contaminants
in the fluid.
This invention further provides a re~circulating
~ilter in the housing of the pump, or other ~luid machine
and provides clean, cooling, lubricating fluid to the
mechanical seal or packing. The existing technology
utilizes either special pumping ring seals or special
housing, which cannot be retro-fitted into existing
pumps.
The prior art does not solve the problem which the
present Invention is devised to solve, ~or example,
United States Patent No. 49128,362 would draw contaminants
into the seal area and would require specially designed pump.
Uni~ed States Patent No. 3,999,882 does not filter contaminants
from the liquid and utilizes specially designed mechanical
seals to develop pumping action. United States Patent No.
4,386,780 describes a system ~or removing contaminants from
the liquid in a centrifugal pump, but requires that the
pump be designed to accomodate a special housing in which
complicated mechanical dev1ces are housed and would make
routine pump maintenance a difficult task. United States
Patent 4,273,509 describes a cleaning unit which operates
externally to the pump on the fluid pressure and ~low
developed by the pump.
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In the drawings which illustrate the embodiments of this
invention and in which the same numbers are used to indicate
the same parts:
FIGURE 1 illustrates a lateral cross-sectional view of
the invention.
FIGURE 2 illustrates a horizontal cross-sectional view
of the invention.
FIGURE 3 illustrates a horizontal cross-sectional view
of the invention in operation within a pump having a mechanical
seal.
FIGURE 4 illustrates the use of the invention in
combination in a pump, using any standard form of packing.
This configuration requires the utilization of ring 1 only.
In the drawings, the number 1 indicates a circular cup-
~haped hollow unit or element closed at the rear thereof,
having vents 3 and 4 therein. This unit 1 is connected to an
annular ring or flange 2, having a further series of vents 5
on the outside circumference of the ring 2. In ~igure 3, the
number 6 indicates a pump housing; the number 7 indicates the
impeller; the number 8 indicates the mechanical seal; the
number 9 indicates the shaft; the number lo indicates
contaminants inside the pump.
The mode of use and operation of this invention is as
follows:
In Figure 3, a mechanical seal 8 is located into the
pump housing 6 between the impeller 7 and shaft 9. The shaft
9, impeller 7 and the mechanical seal 8 being rotated by the
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pump drive-motor, (not shown), impart a rotational motion to
the fluid throughout this area. My Seal Saver encourages and
utilizes this rotational or cyclonic motion, and further
introduces controlled axial motion of the fluid.
The outside ring 1 incorpora~es two series of vehts, one
series 3 on the inside circumference or radially extending
portion thereof and one series 4 on the outside circumference
or arcuate intermediate portion thereof. The vents 3, open
inwardly and direct the rotating flow along the axis of the
shaft 9 toward he mechanical seal 8. The vents 4 open
outwardly and direct the rotating flow towards the impeller 7.
The inside ring or flange 2 has one or more sets of vents 5 on
its outside circumference opening inwardly and directing the
rotating flow toward the vents 4 in the outside circumference
of the outside ring ~. A small gap is left between ring 2 and
the shaft 9. The vents are so sized that vent series 4 is the
largest, and vent series 3 is the smallest. This ensures
velocity increase of fluid entering vents 3. Contaminants 10
thus accelerated in this rotational fluid, will contact ring
2 and be ejected through vent 4. The cleaner fluid will pass
under ring 2 and enter the area of the mechanical seal 8, or
the packing. Any contaminants entering under ring 2, will be
centrifuged to the outside circumference of the seal cavity and
will be ejected by the outflow through the vents 5.
The above specification and disclosure illustrates the
details and embodiments of my discovery and invention.
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It wlll be understood that the foregoin~ specification
and disclosure is an example o~ the preferred embodiment of
my invention and as lt is obvious that my invention may be
changed, adapted or applied in other forms or uses than
are set out herein, I, therefore, claim as my invention
and dlscovery~ all forms, changes and adaptions of my
invention which may be fairly deemed to fall within the
scope of my appended claims.
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SUPPIEMENTa~XY DISCLOSURE
The foregoing has described bri~fly, but accurately, the
concept of the present invention. Further research, ~owever,
has led to a better understanding of the principles involved
in the invention and to additional configurations and
embodiments which utilize those principles. Those principles,
as well as the additional configurations and embodiments will
be described hereinafter with reference to the following
figures wherein:
FIGURE 5 shows, in partial cross-section, an elevational
view of typical fluid equipment utilizing the seal cavity
protector of this invention.
FIGURE 6 is an enlarged cross-sectional view at the
entrance to the seal cavity, showing the present invention
schematically.
FIGURES 7, 8 and 9 are front, rear and side views
respectively of the preferred form of the protector of this
invention.
FIGURE 10 is a cross-section taken on the line 10-lo of
FIGURE 7.
FIGURE 11 is a partial perspective view showing the
fluid flows associated with the present invention.
FIGURE 12 is an enlarged cross-sectional view at the
entrance to the seal cavity.
FIGURE 13 is a view similar to FIGURE 12 showing a
multi-zone protector in accordance with the present invention.
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~ IGURES 14 and 15 show ~ront an~ side ~iews respectively
of a basic form of the present invention.
FIGURE 16 is a view similar to FIGURE 12 showing the
embodiment of FIGURES 14 and 15 in place.
Figure 5 illustrates a typical snvironment for the
device of the present invention. In this case the rotary fluid
e~uipment comprises a centrifugal pump 11 which is operated by
an alectric motor 12. The motor drives a rotary shaft 14
contained within a shaft housing 16 of the bearing housing 13.
The shaft is connected to a centrifugal impeller 18 which, as
it rotates, draws fluid in through inlet 20 and pumps the fluid
out through radial outlet 22. The shaft 14 is typically
supported by bearings 24 and seals 26 are provided to protect
the bearings from contaminants within the fluid which enter the
seal cavity 2~. As seen in Figure 1 the seal cavity 28 is
defined in general by the shaft 14, the shaft housing 16 and
the seals 26.
Figure 6 illustrates a somewhat enlarged view of the
area where the shaft 14 connects to the impeller 18. It is
seen therein that the shaft 14 has a shoulder 30 with a smaller
diameter portion 32 extending therefrom. A threaded portion
34 projects from the portion 32. The impeller 18, with vanes
36, fits over the portion 32 and abuts the shoulder 30. A
washer 38 and nut 40 are drawn tight against the impeller 18
to clamp it to the shaft 14 and a nose piece 42 fits over the
nut, washer and exposed end of the threaded portion 34. With
the impeller in place there is a thin gap G between the inner
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face 4~ o~ the impeller 18 and ~he outer face 46 of the shaft
housing 16.
Seal members 26 are typically held in p~sition on the
shaft by a gland or by set screws (not shown~.
The flow pattern of the fluid in a typical centrifugal
pump sets up countercurrents which flow spirally inwardly
within the gap G, as shown generally by the arrows ~- Such
countercurrents create high pressure areas at the entrance to
the seal cavity 28 and they also carry contaminant material
which, if it enters the seal cavity, can damage the seals 26
and the rotary shaft 14.
It should perhaps be pointed out that the spirally
inward counkercurrent flow (arrows X) will generally be
adjacent the surface 46. Since there are dynamic forces at
work there will, of course, be a spirally outward flow as well,
such as along surface 44, taking fluid away from the shaft
area. However, since the contaminant material carried by the
fluid usually has a greater density than the fluid itself there
can be an accumulation oE contaminant material in the area of
the shaft within the gap G, and possibly within the seal cavity
~8.
The present invention is intended to overcome the
problems indicated above, the present invention taking the form
of a seal cavity protector as shown schematically by reference
number 60 in Figure 6. As seen in Figure 6 the seal cavity
protector is positioned at the entrance to the seal cavity 28.
It should be noted thak all features of the protector 60 are
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not shown in Figure 6. Reference should be made to Figures 7
to 11 to be discussed hereinbelow.
The seal cavity protector can take one of several
configurations depending on whether its prime function is to
reduce the contaminant level in ~he seal cavity and surrounding
areas or to reduce fluid pressures in the seal cavity. The
preferred embodiment will perform both function~ and it is that
embodiment which is shown in Figures 4 to 11. Other
embodiments, both simpler and more sophisticated will be
illustrated later.
Figures 7 to 9 show front, rear and side views of the
seal cavity protector 60 from which it will be seen that it
includes a first annular flange 62 extending outwardly from one
end of a cylindrical axially extending sleeve member 64. A
second annular flange 66 extends inwardly from the other end
of the sleeve member 62 and defines a circular opening 68
through which a shaft 14 can pass with a small clearance.
A cup-shaped annular element 70 has a first generally
cylindrical, axially extending wall portion 70 which, as seen
in Figure 10 fits within the sleeve member 64. The wall
portion 72 should be secured to the sleeve member as ~y welding
to achieve a leak-proof seal therebetween. The element 70 also
includes an annular, generally radially extending, second wall
portion 74 which defines a circular opening 76 of essentially
the same diameter as opening 68 in flange 66 so that the shaft
16 can pass completely through the protector 60. An annular
transition wall portion 78 connects the wall portions 72, 74
togsther and in the drawings the wall portion 78 is shown as
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being arcuate although it could just as easily be straight or
have any other degree of curvature than what is shown.
The element 70 is provided with a plurality of first
vent passages 80 circumferentially spaced apart around the
element and positioned essentially in the transitibn wall
portion 78. Each first vent passage is defined by a first slit
82 extending through the transition wall portion 78, the first
slit being oriented generally radially, and by a second slit
84 which is oriented generally circumferentially adjacent the
lo first wall portion 72. The slits together define a first ~lap
section 86 which is bent oukwardly along a fold line 88 to
provide a passage from the interior zone so~of the protector
to the exterior. I~'
The element 70 is also provided with a plurality of
circumferentially spaced apart second vent passages 92 which
are positioned in the second wall portion 74. Each vent
passage 92 includes a third slit 94 extending radially
outwardly from the opening 76 and a fourth slit 96 which
extends circumferentially from the outer end of the third slit
94. These slits define a second flap section 98 which is bent
inwardly along a fold line 100 to provide a passage from the
exterior to the inner zone 90 within the gap G. The vent
passages 92 are oriented along tangents to the circular opening
76.
The second flange 66 at the "rear" of the protector is
provided with a plurality of circumferentially spaced apart
third vent passages 102. Each vent passage 102 includes a
fifth slit 104 extending generally radially from adjacent the
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sleeve member 6~ and a sixth slit 106 extending generally
circumferentially adjacent the sleeve member. These slits
define a third flap section 108 which is bent inwardly along
a fold line l1o to provide a passage from the seal cavity 28
to the interior zone 118 of the pxotector 60.
The first flange 62 is provided with means, such as
circumferentially spaced apart apertures 112, for securing the
protector 60 to the shaft housing 16. Machine screws 114 could
pass through the apertures 112 for reception in threaded holes
(not shown) in the housing. Preferahly, the housing will be
recessed as shown in Figure 6 so that the front surface of
flange 62 will be generally flush with the housing surface 46.
The first flange 62 is also provided with a plurality
of generally triangular raised flow deflectors 140 which have
angled, sloping walls 142, 144, which in turn are inclined
downwardly and away from a radially outermost apex 146.
Depending on the rotation of the shaft 14 either the walls 142
or 144 will increase the circumferential flow component of the
fluid spiralling inwardly adjacent the protector so as to
improve the capture of such fluid by the vent passages 92 and
to improve thè flow past the outlets of the vent passages 80.
Reference may now be made to Figures 11 and 12 for a
more complete explanation of the operation of the seal cavity
protector of this invention.
Figure 11 shows a seal cavity protector 60 mounted to
a shaft housing 16, at the entrance to seal cavity 28, by way
of machine screws 114. A cen~rifugal impeller 1~ is partially
illustrated, attached in a conventional manner to the shaft 14,
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which shaft passes through the proteckor 60 from the seal
cavity 28.
Figure 11 also illustrates particulate contaminant
material 116 which moves spirally inwardly within the gap G to
the vicinity of the shaft 16. Some of the particulate material
will pass into the seal cavity by way of the clearance gap
between the shaft 14 and the edge of the openings 68 and 76.
Additional particulate material will be forced to enter the
annular zone 118 within the protector by way of the second vent
passages 92. Such vent passages are oriented in the direction
of shaft rotation such that fluid and contaminants rotating
with the shaft 14 and impeller 18 will be forced to pass
through the vent passagas 92. Furthermore, the vent passages
92 are oriented tangentially so as to direct fluids and
contaminants passing therethrough towards the outer reaches of
the zone 118 wherein reside the irst vent passages 80. Such
flow, through the second vent passages 92, is shown by the
arrows B in Figure 11. The rotating flow within the gap G,
caused by the shaft 14, is shown by the arrows A.
As ~luid rotates within the protector's annular zone 118
a portion of the contaminant material contained therein will
accumulate towards the circumferentially outer portion of the
zone due`to centrifugal force, and another relatively clean
portion of the contaminant flow will enter the seal cavity
betwQen the shaft 14 and the edge of the second flange opening
68. As the shaft 14 rotates such material will flow within the
cavity 28 along lines shown by the arrows C, D (Fig. 11) to
exit the cavity via the third vent passages 102, re-entering
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the zone 118. Once a steady state has been r~ached, shortly
after shaft start-up, there will be continuous flow along the
shaft surface into the seal cavity, through the vent passages
92 into the zone 118, through the vent passages 102 into the
zone 118, and through the vent passages 80 bask into the gap
G. The more highly concentrated contaminant material flows
radially outwardly through the gap G in a countercurrent to the
contaminant material flowing spirally inwardly, and in~ardly
flowing material being within a boundary layer close to the
shaft housing surface 46.
Within the seal cavity 28 the path taXen by the
contaminant material will depend on the specific gravity
thereof. Tests have shown that heavier material will follow
a short path (e.g., dotted lines F in Fig~ 12) while lighter
material is more prone to follow a longer path (line K in Fig.
12). Tests have also shown that shortly after start-up the
cavity 28 will be almost empty of contaminant material and that
any material which does enter the cavity is almost immediately
removed therefrom.
It would appear that since there is relative movement
between the fluid in the gap G and the stationary protector 60
there will be a substantial pressure drop in the areas
downstream of the first vent passages and this in turn promotes
the flow of fluid through the second and third vent passages.
Also, the pressure within the zone 118 will be lower than the
pressure within the seal cavity as the fluid i5 moving more
rapidly within the zone 118. This in kurn enhances the fluid
flows within the seal cavity and the flow of fluid, containing
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contaminants, back through the third vent passages 102 into the
zone 118 for ejection through the first vent passages 80.
In view of the fact that there are pressure reductions
axially across the protector 60 it becomes clear that the
protector 60 serves to reduce the pressure within the seal
cavity 28 below the pressure that it would experience ahsent
the protector. Thus given a situation wherein there are
virtually no contaminants to worry about, the present invention
could be used to reduce pressures within the seal cavity 28.
Of course, any protectors installed for the primary purpose of
pressure reduction would still operate to reduce the level of
whatever contaminants might be present in the operating fluid.
Figures 13 to 16 illustrate two directions in which the
design of a pressure reducing seal cavity protector might take.
Figure 13 for example shows a view, similar to Figure 12, in
which there is a plurality of axially adjacent annular zones
118, 118a, 118b..., each additional zone being defined by an
annular flange 66a, 66b... with each flange 66a, 66b... having
a set of fourth vent passages 102a, 102b... defined in the same
manner as passages 102. Each zone will be at a lower pressure
than the axially adjacent zone as one enters the seal cavity
with the cavity being at a pressure lower than what it would
be with but a one-zone protector 60 in place at the entrance
thereto. If, in any particular instance, the pressure in
cavity 28 could be reduced sufficiently by using a multi-zone
protector it might then be possible to replace high-pressure
" seals in the cavity with low-pressure seals with a consiequent
saving in seal purchase and installation costs.
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Figures 1~ to 16 on the other hand illustrate a simpler,
more basic, version of the invention which miyht be used
primarily for pressure reduction. The protector 120 of this
e~oodiment utilizes a cup-shaped element 122 which has an
axially extending first annular wall portion 124, a second
annular wall portion 126 and a transition wall portion 128
which may be arcuate, as shown, straight or of any other
suitable configuration. The front or second wall portion 126
defines a circular opening 130 through which the rotary shaft
0 i5 adapted to pass.
A plurality of circumferentially spaced apart yenerally
tangentially directed vent passages 132 is provided in the
transition wall portion 128, which passages serve to permit
fluid to pass from the seal cavity 28 through the protector to
the gap & between the housing 16 and the impeller. Each vent
passage is defined by a slit 134 which passes through the
transition wall portion 128. On one side of the slit a portion
of the transition wall portion is depressed as at 135 to
provide a larger opening through the wall portion 128.
Optionally, a portion of the transition wall on the other side
of the slit is raised relative, as at 138, to the surrounding
wall material to further increase the opening at the slit. As
seen i~ Figure ~ the depressed portions 132 are all on the
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` ~ ~ same side of the slits and the passage openings are oriented
r~j~y so as to face in the direction of fluid rotation.
As the shaft 14 rotates, fluid within the gap G will
`` ~ pass by the vent passages 132 and will cause a low pressure
area to be created adjacent the element 122 outside the seal
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cavity 28 which will in turn cause fluid to be drawn from the
seal cavity 28 through the vent passages 132. Fluid within the
cavity is replenished through the space between the shaft and
the edge of the opening 130 but the resulting steady-state
operating pressure within the seal cavity 28 will be less than
the normal operating pressure absent the protector 120.
Furthermore any contaminants carried into the cavity 28 will
be quickly removed therefrom due to the outward fluid flow
through the vent passages, as descxibed for the first
embodiment.
If improved performance is required, a set of vent
passages similar to passages 92 could be provided in front wall
portion 126 so as to increase the flow into and then out of
the cavity.
Clearly, the present invention provides a seal cavity
protector which is capable of reducing operating pressures
within the cavity and which also services to scavenye
particulate contaminant material from the seal cavity, thereby
reducing the possibility of damage to the shaft and/or the
seals within the cavity. Specific embodiments of the invention
have been described, which embodiment~ illustrate the
principles associated with the invention.
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