Note: Descriptions are shown in the official language in which they were submitted.
CA 02313058 2000-06-29
SCUM SWEEPER FOR SURFACE FLOATING MATTERS IN A CLARIFYING
TAN~C
FIELD OF THE INVENTION
The present invention generally relates to the removing
operation of scum, sludge or other matters floating at the
surface of water, waste water, sewage or the like in a
clarifying tank, and more particularly to a scum sweeper used
for performing such an operation, and a system using such a
scum sweeper to sweep surface floating matters into a
collector channel or pipe in a clarifying tank.
BACKGROUND
Systems for collecting surface floating matters in a
clarifying tank generally operate in a scrapper-like fashion
to bring floating matters close to collector channels and to
bring heavy waste matters laying at the bottom of the tank
into a collector drain. The mechanisms used for this purpose
usually have an important drawback in that they stop on the
surface at around 1.5 m (5 feet) from the collector channels,
thereby leaving a dead zone where the floating matters
aggregate to form a crust . The systems proposed to cure the
aforesaid mechanisms of this problem are generally complex,
with many partially or totally immerged mechanical components
due to the limited space in which these systems are
installed.
Known in the art are US patents Nos. 3,831,767 (Lefur et
al.); 3,872,017 (Bishop); 4,054,520 (McGivern); 4,470,905
(Pangburn et al.); 4,514,303 (Moore); 4,880,533 (Hondulas):
5,015,393 (Russell et al.); 5,035,681 (Hertel et al.);
5,047,151 (Brandkvist); 5,057,219 (Fujiwara); 5,165,522
(Uttke et al.); 5,242,600 (Meylor et al.); 5,250,178 (Casper
et al.); 5,268,099 (Krofta et al.); 5,269,928 (Leikam);
5,336,417 (Hannum); 5,454,942 (Ljungberg); 5,538,631 (Yeh);
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5,545,324 (Workman); 5,565,099 (Fauret et al.); Re. 35,668
(Albertson); 5,728,304 (Yeh); 5,788,837 (Hannum); 5,948,277
(Frankenberger); 5,968,353 (Herbert et al.); and 6,017,180
(Wilham); which show various sewage treatment devices and
systems illustrating the state of the art.
SUMMARY
An object of the invention is to provide a scum sweeper
for sweeping surface floating matters in a clarifying tank
and forcing them to discharge into a collector channel.
Another object of the invention is to provide such a
scum sweeper, which is simple in construction thus highly
cost-competitive, yet is highly reliable and efficient.
Another object of the invention is to provide such a
scum sweeper, which is compact, and may be hanged over the
water level inside the clarifying tank.
Another object of the invention is to provide such a
scum sweeper, in which only the sweeping blade touches the
surface of the water in the tank.
Another object of the invention is to provide such a
scum sweeper, which is easily adjustable and adaptable to
variable dimensions of old clarifying tanks.
Another object of the invention is to provide such a
scum sweeper, in which the motor is integrated to the
supporting structure so that the sweeping blade may have the
desired length.
Another object of the invention is to provide such a
scum sweeper, which has a low power consumption and requires
only a low maintenance.
Another object of the invention is to provide such a
scum sweeper, which can be installed to operate on the dead
zone of an existing sweeper system.
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Another object of the invention is to provide a system
which is equipped with such a scum sweeper.
According to the present invention, there is provided a
scum sweeper for sweeping surface floating matters in a
clarifying tank to a collector channel, having a supporting
frame provided with mounting brackets for installation of the
supporting frame in the clarifying tank at an above position
with respect to the collector channel. A pair of endless
chains are attached to the supporting frame in parallel with
and spaced from each other. The chains extend substantially
crosswise to the collector channel and define lower and upper
running courses between opposite turning end courses when the
supporting frame is installed in the clarifying tank. A motor
unit is attached to the supporting frame and operatively
coupled to the chains in a driving engagement therewith. A
pair of arms are used to hang an elongated sweeping blade
under the chains with the blade extending substantially
crosswise to the chains. The arms have lower ends attached to
the blade, and upper ends pivotally attached respectively to
the chains at substantially similar positions therealong. The
arms have a length exceeding a space between the lower and
upper running courses. A guiding device locks the arms in a
downward direction with respect to the chains when the arms
travel along the lower running course thereof, whereby the
blade always remains under the chains as a result of a free
pivoting of the arms at the opposite turning end courses.
Preferably, an additional guiding device is provided to
lock the arms in the downward direction when the arms also
travel along the upper running course of the chains.
According to the invention, there is also provided a
scum sweeping system having a clarifying tank, a collector
channel extending in the clarifying tank at a predetermined
level therein and having an elongated longitudinal upper
opening, and a scum sweeper as described above, installed in
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the tank with one of the turning end courses of the chains
extending above the collector channel so that the sweeping
blade reaches the collector channel during its displacement.
BRIEF DESCRIPTION OF THE DRAWINGS
A detailed description of preferred embodiments will be
given herein below with reference to the following drawings,
in which like numbers refer to like elements:
Figure 1 is a perspective view of a scum sweeper
according to the invention;
Figure 2 is a side elevation view of a scum sweeper
according to the invention;
Figure 3 is a perspective view of the non-assembled
components of a scum sweeper according to the invention, for
example for shipping;
Figure 4 is a side elevation view illustrating operation
of a scum sweeper according to the invention, with a
revolving collector channel
Figure 5 is a partial side elevation view illustrating
operation of a scum sweeper according to the invention, with
a collector channel having a ramp;
Figure 6 is a perspective view of a self-supporting and
adjustable assembly of a scum sweeper according to the
invention, without the chain and motor components;
Figures 7, 8, 9 and 10 are respectively a top view, a
side elevation view, an opposite side elevation view and a
perspective view of an arm and guiding shoe assembly of a
scum sweeper according to the invention; and
Figure 11 is a perspective view illustrating a scum
sweeping system according to the invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Figure l, there is shown a scum sweeper
according to the invention, for sweeping surface floating
matters 2 (as shown in Figures 4 and 5) in a clarifying tank
4 to a collector channel 6 (as shown in Figures 4 and 11).
The scum sweeper has a supporting frame that can be made
of a pair of elongated structural members 8 and a structural
beam member 10 extending crosswise at an end of the
structural members 8, provided with mounting brackets 12 for
installation of the supporting frame in the clarifying tank 4
at an above position with respect to the collector channel as
best shown in Figure 11. The supporting frame can take other
configurations depending on the type of supporting structure
which is best adapted to the structure of the clarifying tank
4, so long as it provides a sufficiently strong support that
may extend over the water level in the clarifying tank 4. For
example, it can be made of a single metallic piece instead of
several pieces fitting with one another as in the illustrated
case.
A pair of endless chains 14 are attached to the
supporting frame in parallel with and spaced from each other.
The chains 14 extend crosswise (or almost crosswise) to the
collector channel 6 and define lower and upper opposite
running courses 16, 18 between opposite turning end courses
20, 22 when the supporting frame is installed in the
clarifying tank 4 as best shown in Figure 4. A person skilled
in the art would readily see that the chains 14 can be
possibly replaced by endless belts or other functional
equivalents. Although the term "chain" has been used herein,
it should not be taken in a restrictive or literal sense.
The chains 14 can be hanged under the supporting frame
so that they run about sets of front and rear opposite
sprocket wheels 28, 30 mounted on plates 32 attached to the
structural members 8 of the supporting frame using clamps 34
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or other fasteners. With the clamps 34, the plates 32 can be
slid forward or back over the members 8 for positioning
purposes.
Referring to Figure 6, upper and lower inner guiding
blades 36 extending between the front and rear sprocket
wheels 28, 30 of each set are preferably provided on an inner
side of the chains 14, to prevent undesired bending of the
chains 14 along their courses. The guiding blades 36 can be
secured onto the plates 32.
A motor unit 26 is attached to the supporting frame,
e.g. through one of the plates 32 in the illustrated case,
and is operatively coupled to the chains 14 in a driving
engagement therewith. For this purpose, the sets of front and
rear opposite sprocket wheels 28, 30 (as shown in Figure 1)
can be mounted on common front and rear shafts 38, 40
supported by the plates 32 hanged to the supporting frame,
with one of the shafts 38, 40 being coupled to the motor unit
26, for example the shaft 38 in the illustrated case. The
shafts 38, 40 can be mounted inside protective cylindrical
sheaths 42 if desired. The plates 32 may have rear inclined
slots 71 through which the rear shaft 40 extends and can be
adjustably positioned to stretch the chains 14. The motor
unit 26 may include a gearbox (not illustrated) and be
protected inside a sealed enclosure 44. The motor unit 26 can
be conveniently mounted between the chains 14, so that it
does not take any additional space. Such a feature is
particularly useful when the available space in the
clarifying tank 4 is limited.
Referring to Figure 1, a pair of arms 46 are provided
for hanging an elongated sweeping blade 48 under the chains
14 with the blade 48 extending generally crosswise to the
chains 14. The arms 46 having lower ends attached to the
blade 48, and upper ends pivotally attached respectively to
the chains 14 at similar positions therealong, for proper
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alignment of the blade 48. As a result of the pivotal
attachment of the arms 46 to the chains 14 and thus the free
pivoting of the arms 46 at the opposite turning end courses
20, 22 (see Figures 4 and 5), the weight of the blade 48 will
maintain it in a downwardly hanging state, under the chains.
The arms 46 must therefore have a length exceeding a space
between the lower and upper running courses defined by the
chains 14. The arms 46 preferably have an adjustable height,
e.g. through a telescopic arrangement, for adaptation to
different water levels or tank installations.
As the arms 46 are pivotally attached to the chains 14,
guiding arrangements must be provided for locking the arms 46
in a downward direction with respect to the chains 14 when
the arms 46 travel along the lower running course 16 of the
chains 14. Otherwise, the blade 48 would likely swivel back
and raise, which would impair the desired surface sweeping
action.
Referring to Figures 4 and 10, the guiding arrangements
may be formed of guiding blades 48 extending along the lower
running course of the chains 14, and shoes 50 projecting
perpendicularly or almost perpendicularly from the arms 46
and sliding against the guiding blades 48 when the arms 46
travel along the lower running course 16 of the chains 14.
The shoes 50 can be secured fixedly to the arms 46. In this
case, it might be preferable to use resilient arms 46 so as
to allow the arms 46 to bend slightly backward should the
blade 48 hit something hard.
Alternatively, the shoes 50 may be pivotally
attached to the arms 46. In this case, a spring arrangement
52 may be provided between the shoes 50 and the arms 46
respectively, for urging the arms 46 in a position
perpendicular to the shoes 50. For this purpose, referring to
Figures 7-10, the shoes 50 may have respectively side
projecting shafts 54 rotatably mounted across links 56 of the
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chains 14 and extending beyond opposite sides of the links
56. The upper end of the arms 46 is rotatably mounted on the
shafts 54 on the sides of the links 56 opposite to the shoes
50. Levers 58 project from the shafts 54 and extend in
parallel with the shoes 50 on the opposite sides of the links
56 and beyond a front side of the arms 46. Stops 62 extend
below a rotation point of the arms 46 on the shafts 54 and in
front of the arms 46, to prevent forward pivotal of the arms
46 past a vertical line. Return springs 64 extend
respectively between the levers 58 and the arms 46 and exert
actions urging the arms 46 against the stops 62.
Referring to Figure 4, guiding arrangements are
preferably provided for locking the arms 46 in a downward
direction with respect to the chains 14 when the arms 46 also
travel along the upper running course 16 of the chains 14, to
prevent the swivelling of the arms 46 when returning back
along the upper running course 16, and thus undesired
possible contacts of the sweeping blade 48 with the lower
chain segment. These guiding arrangements can be simply
formed of guiding blades 65 extending along the upper running
course 18 of the chains 14, against which the shoes 50 slide
during their passage.
Referring to Figure 6, the guiding blades 48, 65 may
conveniently be provided by longitudinal upper and lower side
flanges projecting from the plates 32 on outer sides of the
chains 14. The inner blades 36 combined with the outer blades
48, 65 thus conveniently define guiding channels for the
shoes 50.
Referring to Figure 4, in operation, the sweeping
blade 48 is hauled by the running chains 14 to successively
travel, as depicted by the loop 66, across the surface of the
water in the tank 4 to catch scum 2 and bring it to the
collector channel 6 where the blade 48 is then lifted out of
the water and moved back above the water level to be later
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lowered again for a next sweeping pass across the surface of
water. As the blade 48 moves back under the chains 14 and
other components of the scum sweeper, any dripping simply
falls back in the tank 4 without soiling the scum sweeper,
which results in requiring less maintenance and reduces the
risk of ending up with the chains 14 all clogged up.
Furthermore, it allows to use a single sweeping blade 48 that
covers a wide area in the tank 4 instead of requiring a set
of separate blades aligned with one another. To improve the
incoming of the scum 2 into the collector channel 6, the
collector channel 6 can be rotatably mounted in the tank 4
and synchronized as the blade 48 is hauled near it so that
the opening 68 of the channel 6 is turned toward the blade 48
and then turned away when the blade 48 has finished the
sweeping action and returns back over the water level for a
next sweeping operation. The height of the arms 46 supporting
the blade 48 should preferably be adjusted so that the blade
48 has a good immerged portion for catching the floating scum
2. Attention should also preferably be given to the height
level of the blade 48 when returning back over the water
level in order to prevent the blade 48 from touching the
floating scum 2.
Referring to Figure 5, the collector channel 6 can
instead be provided with an inclined ramp 70 downwardly
extending from the opening 68 of the collector channel 6
toward the blade 48 and below the level of the blade 48 so
that it slides on the ramp 70 when it reaches the collector
channel 6 with the arms 46 slightly pivoting rearwards to
follow the rising course of the ramp 70.
Referring to Figure 3, the components of the scum
sweeper according to the invention are shown in an
unassembled configuration, for example for shipping purposes.
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Referring to Figure 11, the scum sweeper may be mounted
to the ceiling wall of the clarifying tank 4, thereby totally
integrating with the tank 4.
While embodiments of this invention have been
illustrated in the accompanying drawings and described above,
it will be evident to those skilled in the art that changes
and modifications may be made therein without departing from
the essence of this invention. All such modifications or
variations are believed to be within the scope of the
invention as defined by the claims appended hereto.
