Note: Descriptions are shown in the official language in which they were submitted.
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TOOL-FREE ADJUSTABLE CLEAN-OUT ASSEMBLY FOR A PUMP
BACKGROUND OF THE INVENTION
Field of the Invention: This invention relates to self-priming
centrifugal pumps, and relates specifically to a clean-out assembly for a self-
priming pump that facilitates access to the interior of the pump and axial
adjustment of the wear plate relative to the impeller.
Description of Related Art: Self-priming centrifugal pumps are well-
known and frequently used in industries where processing fluids with
entrained solids is required. Self-priming pumps, also known as trash
pumps, are characterized as having a casing which houses a suction
chamber and a separation chamber divided by a wall or plenum. An
impeller positioned in a volute section of the pump receives fluid from the
suction chamber and delivers it by centrifugal action into the separation
chamber where it is eventually expelled through an outlet.
The impeller of self-primer pumps are generally of the open type,
meaning that the impeller has a rear shroud, but an open eye into which fluid
flows from the suction chamber. In order for the pump to operate most
efficiently, the impeller must be positioned as close as possible to the wall
of
the volute casing of the pump to minimize recirculation and leakage of fluid
out and around the impeller. To accomplish that, a wear plate is typically
positioned between the volute casing and the open or suction side of the
impeller. The wear plate is positioned in very close proximity to the impeller
vanes to assure efficient pump operation.
As the pump is operated, especially in the processing of fluids with
entrained solids, the vanes of the impeller and/or the wear plate can
become worn down by the solids and the resulting gap or clearance
between the impeller vanes and wear plate causes the pump to operate with
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less efficiency. It then becomes necessary to adjust the distance or
clearance between the impeller and the wear plate to assure a close fit
therebetween.
Pump manufacturers have dealt with this problem in the prior art by
providing various means by which the clearance between the impeller and
the wear plate can be adjusted as needed. In old prior art systems, an
adjustment was provided for axial movement of the rotating assembly (i.e.,
impeller and drive shaft) relative to a stationary wear plate or pump casing.
However, such adjustment means involved the need to correspondingly
adjust the drive shaft relative to the motor, and involved other compensatory
adjustments to structural elements of the pump.
In certain types of pumps, exemplified by self-primer pumps, a clean
out assembly is provided which serves two essential purposes. First, the
clean out assembly provides access to the eye of the impeller through the
suction chamber and provides a convenient means for removing solids or
other debris that may have clogged the impeller. Second, the clean out
assembly has provided a supporting structure for the wear plate and,
consequently, a means for adjusting the axial distance between the wear
plate and impeller.
In presently known clean out assemblies having means for adjusting
the wear plate, the adjustment means or devices are complicated, usually
requiring several adjustment and securement devices, and all require tools
for removing and/or adjusting the several elements to effect an adjustment of
the wear plate. As a result, adjusting the wear plate can be difficult and
time
consuming, and the several elements that comprise the adjustment
mechanism increase the cost of the pump.
Thus, it would be advantageous to provide a clean out assembly that
provides adjustment of the wear plate, but which requires no tools to effect
the adjustment of the wear plate or to remove the clean out assembly for
servicing of the pump, thereby also simplifying manufacture of the pump and
reducing the cost of manufacture.
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BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, a clean out assembly for a
pump, particularly a self-primer-type centrifugal pump, is structured to
provide support for a wear plate and to provide a tool-free means for not
only axially adjusting the wear plate relative to the impeller of the pump,
but
to facilitate removal of the clean out assembly for servicing the impeller of
the pump. As used herein, "tool-free" means that no tools are required to
effect movement or adjustment of the described elements of the clean out
assembly and that such movement is achieved by using one's hand to effect
such adjustment or movement.
The clean out assembly of the present invention generally comprises
an end cover which provides support for a wear plate and is positioned to
cover the access opening in a centrifugal pump axial to the eye of the
impeller. The end cover supports a wear plate that is positioned in close
proximity to the impeller when the end cover is secured in place within the
pump casing. The end cover is attached is the pump casing by securement
apparatus.
The end cover, and thus the wear plate, is axially adjustable relative
to the pump casing and the impeller by adjustment elements that operate
separately from the securement apparatus for attaching the end cover to the
pump casing and, in an especially suitable embodiment may be spaced
from the securement apparatus. By providing adjustment elements operably
separate from the securement means, axial adjustment of the wear plate is
significantly simplified over conventionally-known clean out assemblies for
pumps.
The adjustment elements comprise a threaded shaft that is
threadingly positioned through openings in the end cover. The adjustment
elements also have a handle which can be turned by hand to effect
adjustment of the end cover relative to the pump casing, and thus effect axial
adjustment of the wear plate relative to the impeller. The securement
apparatus for attaching the end cover to the pump casing are also each
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provided with hand nuts that enable tightening of the securement apparatus
by hand. No tools are required to effect attachment or adjustment of the end
cover relative to the pump casing, as is conventional in the prior art.
The simplified structures of the present clean out assembly enable
axial adjustment of the end cover and wear plate without the need for tools,
and enable axial adjustment without removal of any parts. The configuration
of the present clean out assembly effectively reduces the manufacturing and
operating costs of the pump.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
In the drawings, which illustrate what is currently considered to be the
best mode for carrying out the invention:
FIG. 1 is a perspective view of a prior art pump illustrating
conventional structure for a clean out assembly;
FIG. 2 is a view in cross section of the prior art clean out assembly
shown in FIG. 1;
FIG. 3 is a perspective view of a pump illustrating the clean assembly
of the present invention; and
FIG. 4 is a view in cross section of the clean assembly of the present
invention as shown in FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
By way of comparison, a prior art clean out assembly 10 is illustrated
in FIGS. 1 and 2 which comprises, in general, an end cover 12 and a
supporting ring 14 spaced from the end cover 12 by a plurality of stanchions
16. The supporting ring 14 provides a means for attachment thereto of a
wear plate 18, which is connected to the supporting ring 14 by screws 20.
The clean out assembly 10 fits into an opening 22 formed in the pump
casing 24 so that the wear plate 18 is positioned adjacent the impeller 25,
as best seen in FIG. 2.
In the prior art pump of FIG. 1, the clean out assembly 10 is
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connected to the pump casing 24 by a plurality of threaded studs 26 that
extend through holes 28 formed in the end cover 12. The end cover 12 is
secured in place by hand nuts 30 that tighten onto the threaded studs 26.
The means for adjusting the axial position of the wear plate 18
5 relative to the impeller is also associated with the means for attaching
the
end cover 12 to the pump casing 24. Specifically, a threaded adjustment
member 34 threads into each opening 28 in the end cover 12 and slips onto
the threaded stud 26. The adjustment member 34 has a hexagonally-
configured head the corners of which engage with teeth formed in a central
opening 38 of a locking member 36. The opening 38 of the locking member
36 is sized to receive the head of the adjustment member 34.
The locking member 36 is normally bolted to the end cover 12 by the
positioning of a locking bolt 40 and washer 42 through an opening 44 in the
locking member 36. The locking bolt 40 then threads into an opening 46 in
the end cover 12. When the axial position of the wear plate 18 is to be
adjusted (i.e., the axial position of the clean out assembly is to be adjusted
relative to the pump casing 24), the hand nut 30 must first be removed from
the threaded stud 26. The locking member 36 is then removed from the end
cover 12 by using a first tool to loosen and remove the locking bolt 40 and
nut 44.
Each adjustment member 34 is then rotated a selected amount to
move the end cover 12 toward the pump casing 24. A tool different from the
tool used to remove the locking bolt 40 is used for that process. Once the
adjustment members 34 are rotated the desired amount, the locking
member 36 is replaced about the head of the adjustment member 34 and is
locked in place by securement of the locking bolt 40 into place. Each of
these steps requires various tools for effecting the adjustment, and the
adjustment involves manipulation of several structural elements, all of which
results in time-consuming and costly servicing and added cost for
manufacturing of the pump.
The clean out assembly 50 of the present invention, shown in FIGS. 3
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and 4, solves the problems encountered with prior art clean out assemblies
by providing a simplified and tool-free means for attaching the clean out
assembly to the pump casing and for effecting adjustment of the wear plate.
Further, the clean out assembly of the present invention provides means for
attachment of the end cover to the pump casing which is separate from the
axial adjustment structure, thereby eliminating the need to remove structural
elements associated with attachment of the end cover as is required in the
prior art.
The clean out assembly 50 of the present invention comprises an end
cover 52 and a supporting ring 54 to which a wear plate 56 is attached by
some means, such as bolts 58. The supporting ring 54, and thus the wear
plate 56, is spaced from the end cover 52 by a plurality of spacer columns
60. The clean out assembly 50 fits into an opening 62 in the pump casing
64 in the conventional manner to position the wear plate 56 in very close
proximity to the impeller 61, as best seen in FIG. 4.
The end cover 52 of the present invention is secured adjacent the
shoulder 66 surrounding the opening 62 in the pump casing 64 by
securement apparatus comprising a plurality of threaded stud bolts 68 that
extend through openings 70 in the end cover 52. A threaded hand nut 72 is
attachable to each stud bolt 68 providing a means for tightening the end
cover 52 to the pump casing 64.
Axial adjustment of the wear plate 56 in the present invention is
effected by providing two or more adjustment elements 78 that comprise a
threaded shaft 80 and a handle 82. The threaded shaft 80 of the adjustment
element 78 is threaded through a threaded opening 84 in the end cover 52.
As best seen in FIG. 4, the adjustment element 78 is set so that the terminal
end 86 of the threaded shaft 80 seats against the shoulder 66 of the pump
casing 64. As will become apparent for axial adjustment purposes, the end
cover 52 is initially positioned relative to the shoulder 66 of the opening 62
in the pump casing 64 such that a space 88 is provided between the
shoulder 66 and the end cover 52.
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When adjustment of the wear plate 56 is required (i.e., when the wear
plate 56 needs to be brought into closer proximity to the impeller 61), the
hand nuts 72 on the stud bolts 68 are loosened slightly by hand to allow
movement of the end cover 52. The handle 82 of each adjustment element
78 is then rotated by hand to effect movement of the end cover 52 in a
direction toward the pump casing 64, and thus effect axial movement of the
wear plate 56 toward the impeller 61. Movement of the end cover 52 is
accomplished by the fact that the threaded shaft 80 of the adjustment
elements 78 are threaded into the threaded openings 84 in the end cover
52; consequently, rotation of the handles 82 causes the end cover 52 to
move in a direction toward the impeller 61.
Once the wear plate 56 is adjusted to the desired point of proximity
to the impeller 61, the hand nuts 72 are then turned by hand to tighten the
end cover 52 again to the pump casing 64. The adjustment elements 78 of
the invention are structured with self-locking threads that lock the
adjustment
elements 78 into place after movement. However, a locking element of
known structure may also be employed to secure the adjustment elements
78 in place. lndicia 90 may also be provided on the adjustment elements 78
to calibrate the amount by which the axial adjustment is made.
It can be appreciated from the foregoing disclosure that the clean out
assembly of the present invention provides an improved and simplified
means of securing the clean out assembly to the pump casing and effecting
axial adjustment of the wear plate relative to the impeller, while reducing
the
costs of manufacture and operation of the pump. The structure,
configuration and placement of the adjustment elements may vary from that
illustrated and described herein. For example, while illustrated and
described herein as being spaced from the stud bolts that secure the end
cover to the pump casing, the adjustment elements may be located in
proximity to the stud bolts, but operate separately from the stud bolts in a
manner similarly described herein for effecting axial movement of the end
cover, and without the need for tools. Accordingly, reference herein to
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particular details of the clean out assembly of the present invention are by
way of example, and not by way of limitation.
