Note: Descriptions are shown in the official language in which they were submitted.
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Field of the Invention
The present invention relates to an improvement in a
slurry seal for sealing a liquid containing a large amount
of slurry.
Prior Art
A slurry pump heretofore available for pumping up
muddy water and other purposes is provided with such a
slurry seal as shown in Figure 2 as its shaft sealing means.
Referring to Figure 2, that slurry seal is designed
in such a way that a stationary seal ring 103 fitted through
a packing 102 into a flange 101 located on a pump casing and
a rotary seal ring 108 fitted through a packing 107 into a
seal cover 106 secured on the outside of an end of a sleeve
105 attached on the outside of a shaft 104 are mlltually slid
on their sliding planes 103a and 108a while they slide in a
close contact with each other, thereby preventing any
leakage of a sealing liquid sealed in an outer confined
space S leading to an impeller region, not shown, from
around the shaft.
The flange 101 is provided with a quenching hole 109
open on a side 113 of the packing 102 located on the
outside of the stationary seal ring 103, which is positioned
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in opposition to the confined space s. Between the inner
faces of both seal rings 103 and 108 and the outer face of
the sleeve 105 located on the side of the shaft 104, there
is provided a baffle sleeve llo fixed at one end to the
inner end of the flange 101 and having the other end
extending to an inner-peripheral position of the rear end of
the rotary seal ring 108. As a quenching water is supplied
through the quenching hole 109 into the side 113 of the
packing 102, it flows through a gap 111 located on the
outside of the baffle sleeve 110 toward the seal cover 106,
whence it is discharged to the atmosphere A through a gap
between the baffle sleeve 110 and the sleeve 105.
With such a conventional slurry seal as described
above, however, it is known that a slurry of earth and sand
or coal powders contained in large quantities in the liquid
contained in the confined space S causes a premature wearing-
away of the surfaces of the flange 101, both seal rings 103,
108, sleeve 105 and seal cover 106 to contact the confined
space S, decreasing service life.
When the flange 101, both seal rings 103, 108,
sleeve 105 and seal cover 106 are formed of a high-hardness
material with a view to improving their resistance to
slurry, there arises a problem that the assembly is hard to
manufacture for the very reason of hardness.
In view of the foregoing, an object of this
invention is to prevent a premature wearing-away of the
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surface of a slurry seal assembly to contact a confined
space.
SUMMARY OF THE INVENTION
According to this invention, the above-mentioned
object is achieved by the provision of a slurry seal
including a stationary seal ring fitted into a flange fixed
to a casing through a packing, which serves as spring means
as well, and a rotary seal ring fitted into a seal cover
fixed to a sleeve of a shaft through a packing, which serves
as spring means, said seal rings being adapted to be slid on
their axially opposite sliding faces while they are in a
close contact with each other, wherein parts of the surfaces
of said flange, sleeve, seal cover and seal rings, which
face a confined space, are all covered with a synthetic
rubber.
According to the above-mentioned arrangement, the
parts of the surfaces of the flange, sleeve, seal cover and
seal rings, which face a confined space, are all protected
against a slurry by the synthetic rubber which is one of the
materials having an ever more improved wear resistance.
Thus, the flange, sleeve, seal cover and seal rings are
greatly improved in their resistance to slurry.
~RIBF DBSCRIPTION OF THB DRAWINGS
The present invention will now become apparent from
a reading of the following detailed description with
reference to the accompanying drawings, in which: -
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Figure 1 is a partly cut-away sectional view of one
embodiment of the slurry seal according to this invention,
and
Figure 2 is a partly cut-away sectional view of a
conventional structure.
DETAILED ~XPLANATION OF THE INVENTION
Referring Figure 1, a flange 1 is fixed to the inner
periphery of a pump casing, not shown. A shaft 2 is
inserted through the flange 1 to rotate an impeller to be
mounted at the right-handed end of the drawing, although not
illustrated. A sleeve 3 i5 airtightly fitted over the shaft
2 and fixed in place by means of a set screw 4.
A slurry seal assembly is provided between the
flange 1 and the shaft 2 to prevent a slurry-containing
liquid sealed in a confined space S on the inside of the
pump casing from flowing from that space along and around
the shaft to the atmosphere A. As illustrated, this
assembly includes a stationary seal ring 5 formed of silicon
carbide ~SiC) having an increased wear resistance and a
rotary seal ring 6 again formed of silioon carbide, which is
brought in axially ~liding contact with the seal ring 5 to
define sliding planes 5a and 6a.
On the inner periphery of the flange 1 facing the
confined space S, there i9 provided an annular engaging step
~. The stationary seal ring 5 is engaged with the inner
periphery of the step 7 through a packing 8 made of an
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elastomer, so that it is resilliently supported from
outside. A seal cover 9 is airtightly mounted over a collar
end 3a of the sleeve 3 fitted over the shaft 2, which is
located within, and is bolted at 10 in place. At an end of
the seal cover 3 in axial opposition to the flange 1, there
is provided an annular engaging step 11 corresponding to the
first-mentioned step 7. The rotary seal ring 6 is engaged
with the inner periphery of the second step 11 through a
packing 12 similar to the packing 8, so that it is
resilliently supported from the outside.
The rear ends of both seal rings 5 and 6 (opposite
to the sliding planes 5a and 6a) are engaged with metallic
retainers 13 and 14, respectively. The retainers 13 and 14
are in turn peripherally engaged with pins (not shown)
extending axially from the insides of the flange 1 and seal
cover 9, thereby keeping the stationary seal ring 5 fixed
while transmitting a rotational force from the shaft 2 to
the rotary seal ring 6 to turn it.
The packings 8 and 12 are provided to maintain the
airtightness between the flange 1 and the stationary seal
ring 5 and the airtightness between the seal cover 9 and the
rotary seal ring 6 and, at the same time, serve as a spring
means for forcing the seal rings 5 and 6 toward each other
with their resilliency to give the required pressure to
sliding planes 5a and 6a for their sealing.
A quenching hole 15 is formed through the flange 1,
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and a baffle sleeve 16 is provided to form a quenching water
passage extending from the quenching hole 15 within both the
seal rings 5 and 6.
The flange 1 comprises an outer flange member 1~
through which the quenching hole 15 extends and an inner
flange member 18 located on its inside. An inner tapered
face 18a of the inner flange member 18 directing to the
confined space S is lined with a synthetic rubber 19. A
synthetic rubber 20 is covered on an outer face 9a and a
rear end face 9b of the seal cover 9, both faces directing
to the confined space S. A synthetic rubber 21 is covered
on a rear end face 3b of the collar end 3a of the sleeve 3,
which is located adjacent to the above-mentioned rear end
9b, and a synthetic rubber 22 is covered on a part of the
outer face of the stationary seal ring 5, which extends from
the packing 8 into the confined space S. A dust trap 23 is
bonded at its fixed end to a part of the outer face of the
rotary seal ring, which extends from the packing 12 into the
confined space S, and has its free end allowed to be close
to the front face of the seal cover 9 with a minute gap,
covering the packing 12 from the confined space S.
According to the instant embodiment, the metall:i.c
surfaces of the inner flange member 18 of the flange 1, the
seal cover 9, the collar end 3a of the sleeve 3 and the
stationary seal ring 5, which confront the confined space,
are all covered with the synthetic rubber material 19, 20,
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21 and 22 having an improved wear resistance, so that they
are unlikely to be worn away by the slurry contained in the
liquid sealed.
According to the slurry seal of this invention, the
metallic surface of the parts of the flange, sleeve, seal
cover and seal ring, which face the confined space, are all
so protected by a synthetic rubber that they can be
prevented from being worn away by a slurry sealed in the
confined space, improving the resistance of the slurry seal
to slurry.
The foregoing is a description of a preferred
embodiment of the invention which is given here by way of
example only. The invention is not to be taken as limited to
any of the specific features as described, but comprehends
all such variations thereof as come within the scope of the
appended claims.
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