Tracking arrangement for a moving belt

A tracking system for a flexible moving belt wherein an adjustable protuberance arrangement on the belt support structure having a preselected removable and replacable frictional surface which serves to engage against an adjacent face of the belt to align and center such flexible moving belt.

BACKGROUND OF THE INVENTION 
The present invention relates to a tracking arrangement for a moving belt 
and more particularly to a tracking arrangement in the form of a centering 
and alignment structure for a supported moving flexible fibrous filter 
belt or web. 
Moving filter belt arrangements, particularly those filter belts of porous 
fibrous material utilized with various types of pressure, vacuum and 
ambient filter structure for filtering particulate materials have employed 
a number of belt tracking or centering arrangements for the moving filter 
belts. These past tracking arrangements which have included crowned, 
rounded or tapered drive and/or driven rollers have not always proven to 
be effective with centering problems increasing with varying belt tensions 
and extended belt lengths and widths. 
In prior U.S. patents, two types of structures generally have been utilized 
to track and centrally align moving belts--namely those which have 
utilized band members associated with belt support rollers and those which 
have utilized guide shoes associated with the side edges of moveable 
belts. In that group of patents utilizing roller associated band members, 
U.S. Pat. No., 3,116,244, issued to S. S. Davis et al on Dec. 31, 1963, 
teaches belt centering lands integral with moveable belt support rollers, 
the lands extending on the roller in a fixed, helically skewed direction 
to opposite roller extremities; U.S. Pat. No., 3,144,409, issued to L. A. 
Jouhola on Aug. 11, 1964, also teaches similar lands or helical ridges 
formed on a discharge roller to extend to roller extremities with fluid 
pressure between spaced turns serving to transversely balloon a moveable 
support belt; U.S. Pat. No. 3,997,448, issued to E. Woodland on Dec. 14, 
1976, teaches similar helices fixed to a support roller to impose a 
transverse bias on tension bands of a filter belt; and, finally U.S. Pat. 
No. 4,684,011, issued to T. C. Schneider on Aug. 4, 1987, teaches O-rings 
mounted on rollers with traction pressure shoes directly engaging such 
O-rings for effecting roller rotation. In effect, the band members of this 
group of aforementioned patents are functionally and structurally 
different from the novel and unique structural arrangement as set forth 
herein. 
In that group of patents which utilize guide shoes, namely U.S. Pat. Nos. 
3,503,517, issued to A. C. Barnebl on Mar. 30, 1970; No. 3,598,244, issued 
to R. E. Babcock, Jr. on Aug. 10, 1971; No. 3,615,023, issued to A. C. 
Barnebl on Oct. 26, 1971 and No. 3,642,142, issued to A. C. Barnebl et al 
on Feb. 15, 1972--each teaches belt edge gripping structure engaging along 
the side edges of a moveable belt to place a lateral tension thereon. This 
latter group of patents--like the aforediscussed band member patents are 
also functionally and structurally different from the novel inventive 
structural arrangement as set forth herein. 
The present invention provides a new and novel tracking arrangement for a 
moving belt and particularly a flexible, woven fibrous and porous filter 
belt which is straightforward and economical in manufacture and assembly, 
eliminating or reducing many of the problems of past belt tracking 
arrangement, and, at the same time, requiring a minimum of parts and steps 
for effective operation. In addition, the present invention provides a 
structure and method which can be readily moved, adjusted and positioned 
for various types of belts, belt widths, belt fabrics and varying belt 
tensions, allowing for ready and easy adaptation and adjustment to various 
belt types, belt materials and belt sizing with ready and efficient 
removal and replacement of critical alignment parts as well as a proper 
balance of belt centering. At the same time, the novel and useful 
arrangement provides for straightforward and economical changing of 
tension in a moving belt both upon the central lineal axis of movement of 
a longitudinally extending belt and transverse such lineal axis of 
movement across the belt width. 
Various other features of the present invention will become obvious to one 
skilled in the art upon reading the disclosure set forth herein. 
BRIEF SUMMARY OF THE INVENTION 
More particularly the present invention provides a tracking structure for 
maintaining a flexible moving belt in centered alignment on a belt support 
member comprising: a flexible belt of preselected width and with a 
longitudinally central lineal axis mounted on spaced belt support members 
for lineal movement of the belt along the support members, at least one of 
the support members including a substantially cylindrical roller having 
the longitudinal axis thereof extending transversely to the line of lineal 
movement of the flexible belt with the peripheral surface of the roller 
being adjacent the flexible belt; adjustable raised protruberance means 
extending at preselected raised locations from the peripheral surface at 
the roller to engage against an adjacent face of the adjacent flexible 
belt at preselected locations from the adjacent side edges of the belts to 
maintain the moving belt in continuos, centered alignment. Further, the 
present invention provides a novel method of tracking a wide, 
longitudinally extending, flexible moveable belt mounted on drive-driven 
support members for lineal movement of the belt along the longitudinally 
extending central axis thereof comprising: applying preselected tracking 
forces through the drive-driven support members at a preselected location 
away from opposite side edges and to at least one face of the belt when 
the belt is in lineal motion, the forces being substantially normal to the 
line of motion of the belt and at adjustable preselected locations to 
maintain the belt in centered position in its line of motion on the 
support member. Further, the present invention teaches a modified 
arrangement wherein forces applied to the belt are skewed to the line of 
belt motion. 
It is to be understood that one or more changes can be made by one skilled 
in the art in one or more of the several parts of the inventive structure 
disclosed herein and in one or more of the several steps of the novel 
method disclosed herein without departing from the scope or spirit of the 
present invention.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the schematic FIG. 1 of the drawings, longitudinally extending 
filtration tank 2 is disclosed incorporating therein the longitudinally 
extending movable endless filter belt 3. The arrangement as disclosed in 
FIG. 1 is particularly designed for pressure filtration; however, it is to 
be understood that the novel tracking arrangement of the present invention 
is not to be considered as limited to the arrangement disclosed but can be 
utilized for vacuum filtration as well and with any one of a number of 
moving belt structures which require belt tracking and centering 
alignment. 
Cooperative with filtration tank 2 of FIG. 1 and adjacent the lower flight 
of endless moveable filter belt 3 is a belt scraper 4, a belt brush 
mechanism 6, a filter belt back wash mechanism 7, a drip pan 8 and a belt 
tensioning device 9. A suitable fluid inlet and fluid outlet (not shown) 
can be provided in filtration tank 2, advantageously along the top and 
side respectively of tank 2. Belt support drive roller 11(FIG. 2) is 
positioned adjacent to and beneath the upper flight of endless filter belt 
3 at one end of tank 2 with idler or driven support roller 12 being 
positioned adjacent to and below the upper flight of endless belt 3 at the 
opposite end of filtration tank 2. Further, a number of spaced smaller 
idler rollers 10 can be provided to further guide endless filter belt 3 
along its lineal, two flight path of movement. 
In accordance with the present invention and as can be seen more fully in 
the enlarged drawings of the drive and driven rollers of FIGS. 2 and 3 
respectively, the inventive structure includes a flexible belt of 
preselected width and with a longitudinally central lineal axis the belt 3 
being mounted on spaced belt support members for lineal movement of belt 3 
along the support members. In the inventive embodiment disclosed, the 
support members as shown in FIG. 1 of the drawings would be the spaced 
cylindrical drive and driven rollers 11 and 12 respectively (FIGS. 2 and 
3) and the spaced idler rollers 10 (FIGS. 1 and 3), each of the 
cylindrical rollers 11, 12 and 10 having its longitudinal axis extending 
transversely to the line of lineal movement of belt 3 with the peripheral 
surface of each roller being adjacent a face of the belt. Endless filter 
belt 3 in FIG. 1 of the application can be of a woven polyester material 
or can be of any other suitable filter material selected in accordance 
with the filtering conditions involved. Such belts generally are of a 
porous nature, capable of filtering particulate materials from a fluid 
stream in a size range of approximately thirty (30) to five hundred (500) 
microns and generally particulates of a size of approximately one hundred 
(100) microns are to be separated from a fluid stream. It is to be 
understood, however, that specially designed filter belts capable of 
filtering particulates outside the aforenoted size range can also be 
employed with the novel structure of the present invention as filtering 
conditions might dictate. Further, it is to be understood that the filter 
belt widths generally can vary in width in a range of thirty-eight (38) 
inches to ninety-four (94) inches and usually have stitched along opposed 
side edges thereof tightly woven side edge binders extending as much as 
two and one half inches from each edge thereof along opposed belt faces. 
As aforedescribed, belt tensioning device 9 serves to regulate the lineal 
tension on belt 3 through the driven or idler roller 12 (FIG. 1). 
In accordance with one feature of the present invention, at least one of 
the cylindrical drive and driven rollers 11 and 12 (FIGS. 2 and 3 
respectively) can be provided with a set of spaced circumferential O-ring 
receiving grooves extending around the peripheral surface of the roller. 
In the embodiment disclosed in FIGS. 2 and 3, both drive roller 11 and 
driven or idler roller 12 are so provided with such groove sets, each set 
including pairs of spaced O-ring receiving grooves 13 positioned to be 
spaced from opposite ends of the roller. The grooves 13 which are formed 
in tube wrapper 15 snugly surrounding drive roller 11are of sufficient 
depth to accommodate approximately one third (1/3) the diameter of the 
O-rings to be inserted therein to minimize the possibility of O-ring 
displacement from each groove 13, advantageously with the outside groove 
13 of a pair being positioned relative the roller 11 to allow engagement 
of an O-ring mounted in the groove with the adjacent face of filter belt 3 
approximately along a line one (1) inch from the side edge of the belt 3. 
The inside groove of a pair of grooves advantageously is spaced 
approximately one (1) inch from the outside groove of a pair. 
In FIG. 2, drive roller 11, which can be crowned is disclosed as comprised 
of a longitudinally extending cylindrical tube 14 made from a suitably 
selected strong material such as a metal alloy or plastic. Tube 14 has the 
aforementioned surrounding wrapper 15 of resilient material such as a 
suitable elastomer, like Buna.TM. or Viton.TM. in which grooves 13 are 
formed. Tube 15 also is provided at opposite ends fixed to the inner 
periphery thereof with closing plates 16 (only one of which is shown in 
FIG. 2). These plates 16 can also be of a similar material as tube 14. A 
drive shaft 17 extends through plates 16 to extend along the longitudinal 
central axis of tube 14. Shaft 17 is slotted at one end thereof to be 
keyed to a suitable drive motor (not shown). 
A set of resilient O-rings 18 advantageously formed from a synthetic 
material of polymerized butadiene VitonTM are sized to be snugly and 
resiliently mounted in each of the O-ring groove pairs 13 with 
approximately one third of the diameter of each O-ring 18 snugly nesting 
in the groove to minimize possible displacement from engagement with the 
groove. The remaining portion of each O-ring serves as a protuberance to 
engage parallel to the line of belt motion against the adjacent face of 
filter belt 3 approximately one (1) inch and two (2) inches from each of 
the opposed side edges of endless filter belt 3, thus maintaining filter 
belt 3 in central alignment. 
It is to be understood that the present invention is not to be considered 
as limited to the particular O-ring 18 and groove 13 arrangement as above 
described. For example the spacing, number, types of grooves and O-rings 
can vary without departing from the scope or spirit of the invention. For 
example and as disclosed in FIG. 4 of the drawings, the grooves can be so 
formed that the O-rings mounted thereon are advantageously skewed with 
respect to the line of belt motion and to the roller axis on which the 
grooves are formed. In the embodiment of FIG. 4, each groove 19 of a pair 
of grooves of a set is so formed that the O-rings 21 mounted therein can 
be positioned to be so skewed toward each other and to the line of belt 
motion as to actually grip the adjacent face of a filter belt 3 
therebetween. Advantageously, the skewing can be at a an angle to the 
otherwise normal O-ring, parallel to the line of motion position so as to 
be at an angle to the line of belt motion in an approximate range of one 
(1) to ten (10) degrees--the amount and direction of skew depending upon 
such parameters as the nature of material of the filter belt, location of 
filter belt engagement and the engaging frictional faces of the O-rings 
and filter belt. Also, the number of grooves and O-rings and their 
direction of skewing can be varied depending upon the lateral centering 
tension desired for belt 3.