Note: Descriptions are shown in the official language in which they were submitted.
CA 02465485 2004-05-20
CONVEYOR BELT CLEANING SYSTEM
BACKGROUND OF THE INVENTION
The present invention is directed to a system for cleaning
conveyor belts, and particularly to a cleaning assembly for dual conveyor belt
systems.
A conveyor system employing an endless belt may, over time,
require cleaning of the belt surface. This is particularly true when the belt
is
used for conveying an article during processing of the article where portions
of
the article, in one form or another, are transformed. Such transformations may
be accomplished by, for example, applying pressure or heat to the article
being
conveyed.
One form of such a conveying system employs two endless belts.
Each belt traverses a separate belt travel path, with the two belt travel
paths
together defining an article transport path between opposed faces of the
belts.
The article being conveyed, upon entry into the article transport path, is
simultaneously engaged by the opposed faces of the two belts as it moves along
an article processing path. One specific example of such a process is a
cooking
process, where the article being conveyed is a food item which is cooked while
simultaneously being conveyed by the conveyor belt system. In an article
cooking application, heat may be applied to the arti<;Ie as it is conveyed by
the
two belts along the article transport path defined by the belts.
CA 02465485 2004-05-20
2
As the article is heated, fluids in the article may leave the article in
liquid form (i.e., water or oils) or in gas form (i.e., steam or vapor). In
addition,
portions of the article may separate from the article during processing,
causing
debris to remain on the belt once the article has left the article transport
path. As
the endless belts operate over time to transport a plurality of articles, the
build up of
liquids and debris on the belts can become significant, affecting the
perforxxxaxxce of
the belts in processing the article. In addition, the migration of fluids
and/or debris
into the operating equipment for the belts and other associated processing
equipment can degrade the performance of such equipment. Therefore, it is
desirable that any debris or excess liquids created on the belt during
processing be
removed from the belt in an efficient and expeditious manner.
BRIEF SUMMARY OF THE INVENTION
In one embodiment, the present invention is an a,ssernbly for
removing liquids and solids from an endless conveyor belt. The assembly
includes
a plurality of laterally extending liquid absorbent material sheets disposed
adjacent
the belt, with the sheets collectively defining a contact face that is
engageable with
the belt for wiping liquids from the belt.
In another embodiment, the cleaning assembly includes a liquid
absorbent material unit disposed adjacent the belt. The absorbent material
unit
comprises a stack of laterally extending sheets of absorbent material affixed
together at first edges of each of the sheets, and at opposite second edges
the sheets
collectively define a contact face on the absorbent material unit that is
engageable
with the belt for wiping liquids and solids from the belt. Also, at least one
of the
sheets deflects when engaged with the belt.
In another embodiment, the present invention is a method for
removing liquids and solids from an endless conveyor belt. The method includes
advancing the belt, and engaging the belt with a contact face of a liquid
absorbent
material unit disposed adjacent the belt. The absorbent material unit
comprises a
CA 02465485 2004-05-20
3
stack of laterally extending sheets of absorbent material affixed together at
first
edges of each of the sheets, and at opposite second edges the sheets
collectively
define the contact face of the absorbent material unit. At least one of the
sheets
deflects when engaged with the belt.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be further explained with reference to the
drawing figures listed below, wherein like structures are referred to by like
numerals throughout the several views.
FIG. I is a schematic illustration of a conveyor belt system having
the inventive cleaning assembly thereon.
FIG. IA is a sectional view as taken along lines IA--IA in FIG. 1,
showing a pair of belt seals between opposed faces of the belts along an
article
transport path defined by and between the belts.
FIG. 2 is a plan view, as viewed from the article conveying belt face,
of a belt cleaning blade assembly of the present invention.
FIG. 3 is a view of the blade of FIG. 2, as viewed from the
downstream side of the belt.
FIG. 4 is a perspective view of the blade of FIG. 2.
FIG. 5 is a sectional view, as taken along lines 5--5 in FIG. 2.
FIG. 6 is a perspective view of the blade of FIG. 2, and :its associated
filter and liquid collector.
FIG. 7 is a perspective view of an exemplary absorbent material pad
which is disposed for contact with the belt face downstream from the wiper
blade.
FIG. 8 is a perspective view of the absorbent material pad disposed
in a pad holding housing, having a pad exposing window therein.
CA 02465485 2004-05-20
4
FIG. 9 is a sectional view through the housing of FIG. 7,
schematically showing an alternative motor and/or liquid collection system
connected thereto.
FIG. 9A is an enlarged longitudinal section through an absorbent
material pad cartridge and its associated belt, aligned for engagement and
operation.
FIG. 10 is a perspective view of an alternative embodiment of the
belt cleaning absorbent material pad of the present invention.
FIG. 11 is a schematic illustration of a conveyor belt system having
another alternative embodiment of the inventive cleaning assembly thereon.
FIG. 12 is a perspective view of another alternative embodiment the
absorbent material pad unit of the present invention.
FIG. 13 is an enlarged longitudinal section through the absorbent
material pad unit of FIG. 12 and its associated belt, afigned for engagement
and
operation.
FIG. 14 is a schematic illustration of an absorbent material pad
aligned at a tilted angle relative to the belt engaged by the absorbent
matexial pad.
FIG. 15 is an enlarged view of the portion of FIG. 1A indicated by
the dashed outline 11, showing one of the belt seals.
FIG. 16 is a perspective view of a portion of an alternative design for
the belt seal.
FIG. 17 is a partial sectional view showing the belt seal of FIG. 16
disposed between the opposed faces of the belts.
FIG. 18 is a perspective view of a portion of an alternative designed
for the belt seal.
FIG. 19 is a partial sectional view showing the belt seal of FIG. 14
disposed between the opposed face, of the belts.
While the above-identified drawing figures set forth several
embodiments of the invention, other embodiments are also contemplated, as
noted
CA 02465485 2004-05-20
in the discussion. In all cases, this disclosure presents the present
invention by way
of representation and not limitation. It should be understood that nuxzaerous
other
modifications and embodiments can. be devised by those skilled in the art
which fall
within the spirit and scope of the principles of this invention.
CA 02465485 2004-05-20
6
DETAILED DESCRIPTION
FIG. 1 illustrates an article conveying system 20 including the
cleaning assembly components of the present invention. The conveying system 20
has first and second endless belts 22 and 24. Each belt is supported by a
plurality of
rollers such as rollers 26 for belt 22 and rollers 28 for belt 24. The rollers
define a
separate belt travel path for each belt, and at least one of the rollers 26
and 28 for
each belt is driven to move that belt along its respective belt travel path:
Arrows 30
indicate the direction of movement of belt 22, while arrows 32 indicate the
direction of movement of belt 24. Typically, the belts are driven to move at
the
same rate, although not necessarily.
Each belt has a top face for engaging an article being conveyed by
the belt, and an opposite bottom face for engaging its respective rollers.
Accordingly, first belt 22 has a top face 34 and a bottom face 36, and second
belt 24
has a top face 38 and a bottom face 40.
The first and second endless belts 22 and 24 together define an
article transport path 45 between opposed top faces 34 and 38 of the belts 22
and
24, respectively. The article transport path 45 generally consists of the
space
between the opposed top faces of the belts (see space "d" in FIG. 1A), and
extends
longitudinally for so long as the top faces are opposed, and extends laterally
to
adjacent the lateral side edges of the belts. An article to be conveyed, such
as
article 46a, is introduced at a first end of the article transport path 45, is
carried
between the opposed top faces of the belts (as indicated by articles 46b, 46c
and
46d illustrated in phantom in FIG. 1) and exits the article transport path 45
adjacent
a second end thereof (as illustrated by processed article 46e). The article
transport
path 45 may be linear, as illustrated in FIG. l, or may include one or more
curves,
as necessitated by the particular processing being conducted. In addition, the
spacing "d" across the article transport path between opposed top faces of the
belts
CA 02465485 2004-05-20
7
may vary. For instance, the article transport path may be wider in spacing
adjacent
its first end than adjacent its second end. In the illustrated embodiment, the
article
transport path 45 is a generally upright transport path, with its first end
higher than
its second end.
In some applications (e.g., cooking), it may be desired to present a
heated conveying surface to the article 46. In that situation, heating
elements, such
as heater 48 and 50 may be provided to heat the first and second belts 22 and
24
along the article transport path 45.
The endless belts 22 and 24 may be formed from a material that has
the sufficient flexibility to traverse its belt travel path and has other
desired
characteristics, such as a particular frictional characteristic relative to
the article
being transported and its respective support rollers, and if heating is to be
applied to
the article, desired thermal characteristics. In one embodiment, the belt may
be
constructed from a nickel iron alloy known as Invar~" available from Ixnphy
S.A.
Corp., Paris, France. The faces of the belt may also be coated with desired
materials, either to control frictional, thermal or other characteristics.
Examples of
coatings for the top face of the belt are the Excalibur~" coating available
from
Whitford Corporation, West Chester, Pennsylvania and the Teflon's coating
available from E.I. du Pont de Nemours and Company, Wilmington, Delaware.
While FIG. 1 illustrates heating the article as it traverses the article
transport path
45, other manipulation or treatment of the article is also possible,
including, for
example, the application of pressure and/or the introduction of other
components
onto the article (e.g., coatings, flavorings, etc.)
During use, debris and liquid may be deposited on the top faces 34
and 38 of the belts 22 and 24. Such debris typically comes from the article
being
processed, either in the form of article breakage or the extraction of liquids
or gases
therefrom during processing. The presence of debris and excess liquids on the
belts
22 and 24 can degrade performance of the conveying system 20 by, for example,
CA 02465485 2004-05-20
8
adversely affecting the frictional andlor thermal properties of the belt with
respect
to the article being transported. In addition, such debris and liquids may
also
interfere with the engagement of a belt and its respective support rollers,
and with
other associated processing equipment. Conveying systems such as those
illustrated
in FIG. 1 are typically employed in highly automated and high product
throughput
processing systems. Accordingly, extensive downtime of the system for the
purpose of cleaning the belts is unacceptable. Such downtime not only inhibits
the
production of processed articles, but also may be rather labor intensive.
Additional
handling of the system components also may increase the possibility of damage
to
the belt, its associated rollers and other equipment components during
cleaning
and/or removal of a belt for cleaning.
The present invention provides a belt cleaning system which
effectively cleans the belt during conveying operations, thereby avoiding the
necessity for a system shutdown of undesirable duration for belt cleaning. The
inventive system may include a belt wiping blade, absorbent belt wiping pad
and
belt edge containment seals. These components capture debris and liquids on
the
top face of each belt, remove it from the belt and/or direct it away from the
edges
and bottom face of the belt (where it could come into engagement with the
support
rollers and other equipment (e.g., heaters)).
Belt Wiping Blade Assembly
A belt wiping blade assembly 60 is illustrated in cooperation with
the second belt 24 in FIG. 1. The belt wiping blade assembly 60 includes a
blade
62 engaging and extending across the top face 38 of the second belt 24.
Opposite
the blade 62, the belt 24 is supported relative to the blade 62 by one of the
rollers
28. The blade 62 is held in place by suitable structure (not shown) which may
include means for selectively moving the blade 62 toward and away from the
belt
24. The blade 62 is disposed adjacent a lowest extent of the travel path of
the belt
CA 02465485 2004-05-20
9
24, and in one embodiment, is disposed slightly upstream from that lowest
extent,
which causes the waste and debris engaged by the blade 62 to be removed from
the
belt 24 before its natural drop point.
The shape of the blade 62 in one embodiment is illustrated more
fully in FIGS. 2-6. FIG. 2 illustrates the blade in plan view, as viewed from
the top
face 38 of the belt 24 engaging the blade 62. In FIG. 2, lateral side edges 64
and 66
of the belt 24 are illustzated in phantom. The blade 62 has an elongated
central
section 68 and lateral end edges 70 and 72. Each end edge has a diversion ramp
74,
76, respectively, proj ecting upstream relative to belt movement past the
blade 62.
Each diversion ramp 74 and 76 extends outwardly from the central section 68 of
the
blade 62 at an obtuse angle. An upper edge of the blade may be configured to
accommodate the belt face it engages. For instance, each of the diversion
ramps 74
and 76 may have an arced surface adjacent an upper edge 78 of the blade,
and/or a
portion of the upper edge 78 of the elongated section 68 of the blade 62 may
include a radius (see e.g., radius portion 80 along the upper edge 78 of the
blade
62). Accordingly, the blade 62 extends across the entire lateral width of the
belt 24,
and any debris and excess liquid disposed on the top face 38 of the belt 24 is
diverted off of the belt 24 by the blade 62. The diversion ramps 74 and 76
serve to
direct debris and liquids away from the lateral side edges 64 and 66 of the
belt 24.
In one embodiment, the blade is formed from a fluoroelastomer
rubber such as Viton~" material available from E. I. du Pont de Nemours and
Company, Wilmington, Delaware. The blade is softer than the belt surface which
it
engages so that the blade does not scratch the belt as the belt traverses its
travel path
past the stationary blade. The surfaces of the blade contacting the belt are
smooth,
the blade is generally stiff and resilient, and the blade does not absorb or
exhibit an
affinity for any particular form of liquid. In addition, it is important that
the blade
have a melt temperature higher than the possible temperature of the belt. In
one
embodiment, the blade has a melt temperature higher than 350°F
(177°C),
CA 02465485 2004-11-26
i0
preferably higher than 400°F (204°C), and more preferably higher
than 450°F
(232°C).
In one embodiment, a belt wiping blade assembly is provided for
each of the belts 22 and 24. The belt wiping blade assembly 60 described above
is
disclosed with respect to the second belt 24, while another belt wiping blade
assembly 90 provided for the first belt 22, as seen in FIG. 1. The belt wiping
blade
assembly 90 has a blade 92, which in all regards is the same as the blade 62.
The
belt wiping blade assemblies are identically oriented with respect to their
respective
belts, although the orientations are mirror images of one another, as seen in
FIG. 1.
In each belt wiping blade assembly, a filter or screen is disposed
below the blade. Debris and liquid removed from the belt by the blade is
directed
onto the filter. Liquid flows through the filter, while debris is collected on
and in
the filter for disposal. The belt wiping blade assembly 60 has a filter 94
disposed
below the blade 62, while the belt wiping blade assembly 90 has a filter 96
disposed
below the blade 92 (see FIGS. 1 and 5). The filters 94 and 96 may be formed
from
a layer of scrim material or nonwoven material, for example, with voids
allowing
liquid to flow through and a mat or sheet of fibers which stop the flow of
debris and
other particulate matter therethrough. For example, a woven fiberglass or
polyester
scrim or nonwoven polymeric fibers may suffice as the filter. The filters 94
and 96
are supported by suitable structure (not shown in FIGS. 1 and 5) under their
respective blades 62 and 92.
As the blade becomes soiled or damaged in use, it may be removed
for cleaning or replacement independently of its respective filter.
Alternatively, the
blade and filter may be connected in cartridge form (as indicated
schematically by
phantom cartridge 98 in FIG. 5) for joint removal (for cleaning or
replacement)
relative to their respective belt. FIG. 6 illustrates an embodiment wherein
the filter
94 is laterally slideably received in a housing 100, and has an endplate 102
connected thereto for facilitating slideable removal of the filter 94 relative
to the
CA 02465485 2004-11-26
11
housing 100, as indicated by arrows 104. The filter 94 is thus replaceable
without
removal of the blade 62 thereabove.
A liquid collector is disposed under the filter of each belt wiping
blade assembly to collect liquid removed from the top face of the belt by the
blade
and run through its filter. The liquid collector can be a trough, or a
diverter tray
with a drain and conduits leading to a liquid collection reservoir at some
remote
location (not shown). FIG. 1 illustrates the liquid collectors as troughs 106
and 108
of the belt wiping blade assembly 60 and 90, respectively. 1n FIG. 6, the
trough 106
for the belt wiping blade assembly 60 is shown with a sloped bottom 110,
tilting
downwardly from one lateral side edge of the belt 24 to the other side edge,
with a
drain conduit 112 at the lowest end of the sloped bottom 110. The liquid
collectors
106 and 108 are supported relative to the respective belts, blades and filters
by
suitable structure (not shown). If the liquid collector is not provided with a
drain, it
must be accessible and removable for cleaning and disposal of any liquid
therein.
Absorbent Pad Assembly
In spite of the fact that each belt has a blade wiping against it for
liquid and debris removal, not all liquids and solids may be removed from a
belt by
its respective blade. Accordingly, an absorbent material can be brought into
engagement with the top face of each belt downstream from the blade for
further
removal of liquids and solids from the belt. The absorbent material is urged
into
contact with the top face of the belt to wick off and further to wipe off
liquids and
solids borne by the belt.
FIG. 7 illustrates an exemplary design for an absorbent pad 120. A
core 122 extending along a central axis 124 has a plurality of lobes 126 of
absorbent
material 128 affixed thereto so that the lobes 126 radiate outwardly
therefrom.
Outer edges 129 of the lobes 126 cooperatively define the absorbent pad 120 as
a
generally cylindrical pad assembly. In use, as seen in FIG. 9A, an arced
segment of
CA 02465485 2004-05-20
12
the cylindrical pad assembly is brought into contact with the top face of one
of the
belts, to define a contact face of the absorbent pad. Although disclosed as a
generally cylindrically shaped absorbent pad 120, the absorbent material 128
can
take other forms. For example, the absorbent material can be a static pad
(see, e.g.,
FIG. 12) or could be disposed as a belt (endless or running end to end) which
can
have an arced portion thereof brought into contact with the top face of the
belt to be
cleaned.
The absorbent material is flexible, and may be formed from a
nonwoven material, a woven material, a knit material, or combinations thereof.
Suitable materials include polyethylene, polypropylene, polyolefins,
polyesters and
nylons. In one embodiment, the absorbent material has certain desired
absorbency
.,
characteristics, such as being oleophilic, hydrophilic, or combinations
thereof. The
absorbent material must also be softer than the belt face against which it is
engaged,
so that the belt face is not scratched or otherwise abraded during the
cleaning
process. Further, the absorbent material should be nonshedding of fibers so
that it
does not itself cantaminate the belt with debris (and likewise does not
contaminate
articles conveyed by the belt, a significant concern when the articles are
food
items). In one embodiment, a scrim is disposed between the absorbent material
and
top face of its respective belt. In addition, it is important that the
absorbent material
have a melt temperature higher than the possible temperature of the belt. In
one
embodiment, the absorbent material has a melt temperature higher than
350°F
(177°C), preferably higher than 400°F (204°C), and more
preferably higher than
450°F (232°C).
The absorbent pad 120 is shown in FIG. 1 in contact with the first
belt 122 for cleaning. A similar absorbent pad 130 is shown in FIG. 1, in
contact
with the second belt 24. The absorbent pads 120 and 130 are generally
identical,
although oriented for mirror image operation with respect to their respective
belts
22 and 24.
CA 02465485 2004-11-26
13
In one embodiment, the absorbent pad 120 is rotated about its axis
124 to engage different portions thereof (as its contact face) with its
respective belt
(see, e.g., arrows 132 in FIG. 1). Thus, a clean portion of the outer
cylindrical
surface of the absorbent pad 120 can be indexed into position to engage the
belt for
belt cleaning. The cylindrically shaped absorbent pad 120 is not rotated to
move its
outer surface as the same rate as its belt, but may be indexed periodically
(either
manually or by a motor or other mechanized means). Once the cylindrically
shaped
absorbent pad 120 has been completely indexed through an entire rotation about
its
axis 124, or is otherwise deemed to be fully saturated with liquid, it is
replaced with
a fresh absorbent pad.
FIGS. 8, 9 and 9A illustrate the absorbent pad 120 borne by a pad
housing 136, thereby defining a pad cartridge 137. The housing 136 has an
enclosure defined by a cylindrical sidewall 138 and opposed endcaps 139, with
a
laterally disposed window 140 in the sidewall 138 for exposure of a portion of
the
absorbent pad 120. As best seen in FIG. 9A, the window 140 is aligned to
expose
one or more lobes 126 of the absorbent material 128 of the absorbent pad 120.
In
one embodiment, exposed lobes 126a, 126b and 126c are in engagement with the
top face 34 of the belt 22 as it moves past the absorbent material 120.
Indexing the
cylindrically shaped absorbent material 128 about its axis 124 (in direction
of
arrows 132) will bring the next lobe 126d into contact with the belt 22, while
allowing lobe 126a (now fully saturated with liquid) to be moved out of
engagement with the belt. Those lobes in contact with the top face of the belt
deform to increase the surface area of absorbent material in contact with the
belt
face and "wipe" the belt face with absorbent material.
The absorbent pad 120 (or if in cartridge form, the cartridge 137), is
supported by suitable structure (not shown) relative to its respective belt.
The
absorbent pad 120 is removable and replaceable, so that once fully saturated
with
liquid, a fresh pad can be substituted for the soiled one. The pad may be
removable
CA 02465485 2004-11-26
14
from adjacent the belt, from its housing if one is provided, or it may be
replaced in
cartridge form (i.e., the pad and housing are removed and replaced together).
As illustrated in FIG. 9, a motor 150 may be rotatably coupled by
suitable means to the core 122 (as shown in FIG. 7) of the absorbent pad 120,
for
rotation thereof relative to the housing 136. Suitable bearings 152 may be
provided
to facilitate such rotation. The motor can thus be activated periodically to
rotate the
absorbent pad 120 and sequentially present fresh absorbent material to the
belt. In
another embodiment, the core is formed as a hollow tube 153 which is
perforated
(as at 154). The hollow tube 153 is sealed at one end, while at its other end
it is
coupled to a liquid evacuation system 155 having a pump 156 and liquid
collector
158. Thus, absorption of liquid from the belt is aided by drawing a vacuum
through
the absorbent material to draw liquid from its outer edges to the core (a
hollow
tube) and then out of the core to be collected. Alternatively, removal of the
liquid
from the core is accomplished via mechanical means such as a screw auger,
piston
drive or other fluid conveyance mechanism, alone or in combination with a
vacuum
draw. In addition, the axis of the core can be tilted relative to horizontal
to aid in
liquid drainage toward its lower end, and removal therefrom.
In one embodiment, means are provided for sensing when the
absorbent pad is fully saturated with liquid, and thus needs removal for
cleaning or
replacement. Such sensing means may simply be a timer based upon usage,
indicating a presumed degree of liquid saturation over time of operation, a
sensor
based on linear exposure of the belt to the absorbent material, or a weight
based
sensor, detecting the change in weight of the absorbent pad as it becomes
saturated
with liquid. In another embodiment, the sensor may be an optical sensor 160
mounted, for example, on the core. The optical sensor 160 may be aligned to be
directed radially outwardly from the core, to detect the change in opacity of
the
absorbent material as it becomes saturated with liquid (the absorbent material
becomes less opaque as it becomes more saturated). The sensor may also be used
CA 02465485 2004-05-20
to detect partial saturation, and thus provide a signal (e.g., to the motor
15) to
facilitate indexed advance of the absorbent material relative to the belt.
FIG. 10 illustrates an alternative absorbent pad design 164. The
alternate pad design 164 is aligned to present a single lateral pad surface
166 of
absorbent material 168 to a passing belt. The absorbent pad 164 is not
indexable
relative to the belt, and once the absorbent material 168 is fully saturated
with
liquid, the absorbent pad 164 is simply replaced, or removed for cleaning and
reuse.
The pad surface 166 is positioned by suitable structure (not shown) relative
to the
face of its respective belt to be engaged so that it deflects against it to
present the
largest, possible surface area, and thereby "wipe" the face of the belt while
absorbing liquids therefrom.
As illustrated by phantom absorbent pads 162 in FIG. 1, absorbent
material may be disposed to wipe against the bottom faces 36 and 40 of the
belts 22
and 24, thereby removing by absorption any residual liquid thereon (that may
have
migrated to the bottom face during processing from the top face of the belt).
FIG. 11 illustrates the article conveying system 20 including another
alternative absorbent pad design, which comprises an absorbent pad unit 320
located along the top face 34 of belt 22. Absorbent pad unit 320 may be
located
almost anywhere along belt 22, with the particular location chosen as a matter
of
convenience and available space. hx one embodiment, for example, the absorbent
pad unit 320 is attached to the belt wiping blade assembly 90. In a preferred
embodiment, the absorbent pad unit 320 is located along an outer vertical
segment
of the belt 22. It is further desirable to locate the absorbent pad unit 320
at the
hottest possible location so that grease on the belt 22 is at its most
soluble, for
example, by locating the absorbent pad unit 320 close to the roller 26 at the
bottom
of the outer vertical segment of the belt 22. A mirror image absorbent pad
unit 322
is located along the belt 24, in the same manner as for absorbent pad unit
320.
CA 02465485 2004-05-20
16
As seen in FIG. 12, an alternative pad unit 320 comprises a plurality
of individual sheets 326 of liquid absorbent material 328 laterally disposed
in a
stack. In one embodiment, the sheets are horizontally disposed and the stack
is
vertically disposed. The individual sheets 326 are bonded together along first
edges
329 of each of the sheets 326, along a first face 332 of absorbent pad unit
320. A
second contact face 340 is defined by the opposite second edges 333 of the
sheets
326. In operation, the contact face 340 engages the top face 34 of the belt
22. In
one embodiment, the absorbent pad unit 320 is not indexable relative to the
belt,
and once the absorbent material 328 is fully saturated with liquid from the
belt 22,
the absorbent pad unit 320 is simply replaced, or removed for cleaning and
reuse.
The absorbent material 328 may be any of the types described with
respect to the previous embodiments. In a preferred embodiment, the absorbent
material 328 is spunbond polyethylene terephthalate (PET). The individual
sheets
326 are also generally about 20-30 mils (0.5080-0.7620 mm) thick. In a
preferred
embodiment, each sheet 326 is about 22 mils (0.5588 mm) thick.
In one embodiment, the absorbent pad unit 320 has a height H of 0.5
inches (1.27 cm), a length L of 7.75 inches (19.685 cm), and a width W of 1.0
inches (2.54 cm). In another embodiment, the absorbent pad unit 320 has a
height
H of 0.5 inches (1.27 cm), a length I, of 6.75 inches (17.145 cm), and a width
W of
1.0 inches (2.54 cm). In order to achieve a height H of 0.5 inches ( 1.1.27
cm),
when individual sheets 326 are of 22 mils (0.5588 mm) thickness, the absorbent
pad
unit 320 typically comprises about 38-40 individual sheets 326.
FIG. 13 illustrates the absorbent pad unit 320 positioned relative the
belt 22. The absorbent pad unit 320 is typically positioned perpendicular to
the belt
22. The absorbent pad unit 320 is positioned such that one or more individual
sheets 326 deflect against ("wipe") the top face 34 of the belt 22. The
absorbent
pad unit 320 is loaded in tension relative to the top face 34 of the belt 22,
as the
contact face 340 of the absorbent pad unit 320 maintains intimate contact with
the
CA 02465485 2004-05-20
17
top face 34 of the belt 22, generally causing two or mare of the individual
sheets
326 to fan apart at or near the contact face 340. For example, the absorbent
pad
unit 320 may have one-sixteenth inch (0.15875 cm) deflection spacing, meaning
the
contact face 340 would extend one-sixteenth of an inch (0.15875 em) beyond the
top surface 34 of the belt 22 if not for deflection of the sheets 326 of the
absorbent
pad unit 320 caused by contact with the top surface 34 of the belt 22.
The first edges 329 of the individual sheets 326 may be bonded
together using any suitable technique, including: the use of adhesives;
potting;
thermal bonding such as roll, plate, wire, ultrasonic, induction or other
thermal
bonding techniques; or mechanically clamping or retaining the sheets 326
together.
Bonding the individual sheets 326 at the first face 332 prevents individual
sheets
326 from separating from the absorbent pad unit 320 as the sheets 326 fan
apart
near the second contact face 340.
In one embodiment; means are provided for sensing when the
absorbent pad unit 320 is fully saturated with liquid, and thus needs removal
for
cleaning or replacement. Such sensing means may simply be a timer based upon
time of usage, indicating a presumed degree of liquid saturation over time of
operation, a sensor based on linear exposure of the belt 22 to the absorbent
material
328, or a weight based sensor, detecting the change in weight of the absorbent
pad
320 as it becomes saturated with liquid. In another embodiment, the sensor may
be
an optical sensor (not shown) mounted, for example, adjacent the pad 320. The
optical sensor may be configured to detect the change in opacity of the
absorbent
material (as it becomes more saturated).
As illustrated by phantom absorbent pad units 344 in FIG. 1 l, an
absorbent material pad unit, comprising individual sheets of absorbent
material,
may be disposed to engage (i.e., wipe against) the bottom faces 36 and 40 of
the
belts 22 and 24. Absorbent pads may be arranged nearly anywhere along the
bottom faces 36 and 40 of the belts 22 and 24, with the particular locatian
chosen as
CA 02465485 2004-05-20
18
a matter of convenience and available space. Typically, absorbent pad units
344 are
located near absorbent pad units 320 and 322, respectively. In further
embodiments, performance may be enhanced when support is provided to the belts
22 and 24 directly opposite the absorbent pad units 320 and 322, respectively,
such
as where absorbent pad units 344 are positioned directly opposite absorbent
pad
units 320 and 322 on either sides of the respective belts 22 and 24.
In order to increase the amount of absorbent material exposed to the
belt face, the absorbent material may be tilted relative to the belt travel
direction
(see, e.g., FIG. 14). Accordingly, the absorbent material (whether in the form
128
shown in FIGS. 1 and 7-9A, in the form 168 shown in FIG. 10, in the form 320
shown in FIGS. 11-13, or in some other functionally equivalent form) is
disposed as
at 178 in FIG. 14, relative to a belt such as belt 24. The direction of belt
travel is
indicated by arrow 179. As seen, absorbent material 178 is tilted relative to
the belt
24 (i.e., tilted relative to horizontal). Thus, the absorbent material can be
longer
than the lateral width of the belt, and thereby present a greater surface area
to the
belt face which passes by the absorbent material.
Belt Edge Seals
As noted above, it is undesirable that liquid and/or debris migrate
from the top face of a belt to its edges or to its bottom face. The inventive
cleaning
assembly thus includes edge seals i:or placement between the opposed belts
along
the article transport path. The edge seals serve as a physical barrier to
contain
liquids and debris from reaching the lateral side edges of the belts. As seen
in FIG.
1A, the first belt 22 has lateral side edges 180 and 182, while the second
belt 24, as
shown in FIG. 2, has lateral side edges 64 and 66. Along the article transport
path
45, the opposed top faces 34 and 38 of the belts 22 and 24 are spaced apart by
a
distance "d". A first resilient edge seal 190 is disposed across the space "d"
CA 02465485 2004-11-26
19
adjacent the lateral side edges 180 and 64, while a second resilient edge seal
192 is
disposed adjacent opposed lateral side edges 182 and 66.
In one embodiment (see, e.g., FIGS. 1A and 15), each edge seal is y-
shaped, and has longitudinally extending legs or fins resiliently urged
outwardly
against the top faces of the opposed belts. Edge seal 190 has legs 190a and
190b,
while edge seal 192 has legs 192a and 192b. The distal end of each leg or fin
is
rounded for smooth engagement with the top face of its respective belt. A
center
dorsal fin 195 (or series of tabs) is provided on edge seal 190 for ease of
manipulation, mounting and handling thereof. Edge seal 192 likewise has a
center
dorsal fin 197. The edge seals thus prevent liquid from moving to the lateral
side
edges of the belts, and further from moving to the bottom side of each belt.
In
addition, gasses (such as steam) that may be generated during processing of
the
article along the article transport path between the belts can be contained by
the
edge seals and diverted to an appropriate exhaust path.
In an alternative embodiment (see, e.g., FIGS. 16 and 17), the edge
seal is an elongate compressible solid member 200, having opposed belt
engagement edges 202 and 204. The solid member 200 is resilient and is
inserted
(by twisting and/or compression thereof) between the opposed belts 22 and 24,
as
seen in FIG. 17, with its edges 202 and 204 pressed against the top faces 34
and 38
of the belts. In another alternative embodiment of the edge seal (see, e.g.,
FIGS. 18
and 19), the edge seal is a hollow elongated tubular member 206. The tubular
member 206 is resilient and is inserted between the opposed belts 22 and 24.
It
deforms to fit the gap "d" therebetween and form a seal as it is pressed
against the
top faces 34 and 38 of each belt. It is contemplated that solid member 200 and
tubular member 206 will be mounted at their ends relative to the article
conveying
system.
In one embodiment, the edge seals are formed from, for example, a
polyester or nylon material which is softer than the belts, so that scratching
of the
CA 02465485 2004-05-20
belts does not occur during use. In all embodiments of the edge seal, the
material
forming the seal is resilient enough to accommodate changes in dimension "d"
along the article transport path. The edge seals are flexible, resilient and
non-
absorbing of liquids. In addition, it is important that the edge seals have a
melting
temperature higher than the possible temperature of the belt. In one
embodiment,
the belt seals have a melt temperature higher than 350°F (
177°C), preferably higher
than 400°F (204°C), and more preferably higher than 450°F
(232°C). The edge
seals are easily replaceable when worn or for access to the article transport
path
between the opposed belts.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize that changes
may
be made in form and detail without departing from the spirit and scope of the
invention.
