Positive tracking pulley and belt construction

An endless belt apparatus (10) which can be used in either a timing, driving, and/or load carrying system, has a generally cylindrical drive pulley (12) in the outer surface (22) of which is provided recesses for engaging with an associated belt (26) including a planar web (28) provided with projections (34, 34') arranged in a symmetrical matrix for positively engaging with the recesses of the pulley for tracking and/or advancing the belt. Similar recesses provided in the other pulleys of the system will permit the belt to rotate such pulleys as a function of the rotation of the drive pulley. Circumferential grooves either recessed (24) or formed by annular rings (82) can be provided on the pulley for tracking purposes and axial channels (64) or sprocket teeth (90) for drive purposes, although it is contemplated that a symmetrical matrix of recesses (74) be provided on the pulley for matingly receiving the matrix of projections (34, 34') and permitting both training and advancing, in either direction, of the belt (26) simultaneously.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to endless belt systems, particularly to a 
cog belt arrangement especially suited for positive tracking and positive 
drive applications. 
2. Description of the Prior Art 
My prior U.S. Pat. No. 4,011,939, issued Mar. 15, 1977, discloses a 
conveyor system including a drive pulley and a return pulley, either or 
both of which are of relatively large diameter and are provided with a 
plurality of cleat-receiving annular grooves. A conveyor belt provided 
with a plurality of longitudinal rows, or columns, of cleats, or 
projections, protruding from it engages the pulleys so that at least some 
of the columns engage with the grooves in the pulleys and assure good 
tracking of the belt. The projections are sized relative to the web of the 
conveyor belt such that the belt web itself normally does not contact the 
associated pulley. Interaction between the pulley grooves and the cleats 
provides drive force transmission from pulley to belt as well as providing 
a positive tracking, or belt alignment, even under severe off-center, or 
side load, conditions. At least some of the grooves can be inclined 
relative to a normal to the axis of rotation of the pulley and belt. 
It also is known to provide cogs, or projections, on the inside surface of 
a drive belt in order to improve the flex of the belt and permit it to 
pass around pulleys of relatively small diameter. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a conveyor belt having 
a projection matrix permitting more uniform tracking, or side-load, 
distribution than known belts having pulley engaging projections. 
It is another object of the present invention to provide a projection 
matrix endless belt that can be used with smooth as well as grooved 
pulleys of relatively small diameters. 
It is still another object of the present invention to provide an endless 
belt which can be used in positive drive systems, and which facilitates 
both forward and reverse belt movement. 
A still further object of the present invention is to provide a pulley and 
associated belt for a positive belt drive system which can be used for 
either timing or load carrying purposes, or both. 
There and other objects are achieved according to the present invention by 
providing a conveyor belt apparatus comprising a planar web having a 
longitudinal extent and a pair of parallel surfaces. One of the surfaces 
is provided with a plurality of projections arranged in a plurality of 
rows and columns for forming a matrix engageable with an outer peripheral 
surface of a pulley associated with the belt. According to a preferred 
feature of the present invention, each of the projections is in the form 
of a truncated geometrical solid converging away from the web so as to 
maximize the possible amount of flex of the belt. Advantageously, a 
cylindrical portion extends from the truncated solid and away from the 
surface of the web for increasing the effective length of the projection. 
Provision of a recess on the pulley for receiving the projections can 
permit the positive tracking of the web relative to the pulley, for which 
purpose circumferential grooves can be provided around the pulley, or 
permit a positive belt drive feature, for which purpose channels or 
sprockets can be provided on the pulley so as to extend parallel to the 
axis of rotation of the pulley, or permit both positive tracking and belt 
drive. The latter can be accomplished according to a particularly 
advantageous feature of the invention wherein the pulley is provided with 
a symmetrical matrix of sockets on the surface thereof, which matrix of 
sockets matches the matrix of projections on the belt web so that the 
sockets engagingly receive the projections contacting the pulley at any 
point in time. Alternatively, a combination of grooves and sprockets can 
be employed for both driving and tracking. 
An advantage of the present invention is that it permits light-duty belts 
to be used with very small diameter pulleys. 
Still another advantage of the invention is that a belt can be driven 
positively in either direction. 
Another advantage of the present invention is that a single belt can be 
used for load carrying, including friction increasing functions, timing 
and positive drive purposes.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now more particularly to FIGS. 1 and 2 of the drawings, an 
endless conveyor system 10 according to the present invention comprises a 
generally cylindrical head or drive pulley 12 and a return pulley 14, each 
including a respective shaft 16 and 18 defining an axis of rotation for 
the pulley 12, 14. The drive pulley 12 has an outer cylindrical surface 20 
in which is provided a recessed arrangement 22 in the form of one or more 
circumferential grooves 24. An endless conveyor belt 26 including a planar 
web 28 is disposed extending around pulleys 12 and 14 for being driven by 
pulley 12. Web 28, which can be fabricated from polyvinyl chloride, 
urethane, rubber, and the like, has a pair of substantially parallel 
surfaces 30 and 32, of which surface 30 is shown as smooth for creating a 
load-carrying surface and surface 32 is provided with a plurality of 
projections 34 disposed in a plurality of rows 36 and columns 38 for 
forming a symmetrical matrix 40 of a rectangular grid. Surface 30, 
normally disposed for load-carrying, preferably is a layer 35 (FIG. 2) of 
polyester, and the like. The size of the projections 34, which are 
themselves symmetrical as to be described below, and the spacing between 
them is such as to permit projections 34 to positively engage in grooves 
24 of pulley 12 and cause belt 12 to be kept in a central position on 
pulley 12 despite variations in side-loadings in the belt 26. 
It is to be understood that pulley 14 can be provided with grooves (not 
shown) similar to grooves 24 in pulley 12 if so desired. Further, belt 26 
can be used with smoothed surfaced pulleys (not shown) if desired, with 
projections 34 functioning as friction increasers in an advantageous 
manner. The latter is one of the advantages of the invention to be 
described in detail below. Each of the soft, long wearing projections 34, 
which can be constructed from a filled or nonfilled material (for example, 
carbon fibers) is in the form of a truncated geometric solid, in this case 
a truncated pyramid 42 having a polygonal base, converging away from 
surface 32 of web 28. More specifically, the four side walls of pyramid 42 
converge from a larger, square, planar base 44 at surface 32 to a smaller, 
square, planar base 46 spaced from but substantially parallel to base 44 
to form a frustom of a pyramid. This construction permits the projections 
34 to pass around a pulley of relatively small diameter without 
interfering with one another. 
A belt 26 according to the invention can be molded in a conventional 
manner, or can be formed as a flat belt and grooves and/or projections cut 
into an inner surface of the belt as by a cutting wheel (not shown). Once 
cut, the belt can be reversed if desired to place the projections on an 
outer surface of the belt. 
Referring now to FIG. 3 of the drawings, an alternative embodiment of a 
projection according to the invention, designated 34', has a truncated 
pyramid 48 converging from a large base 50 to a smaller base 52, similar 
to pyramid 42, but a shorter distance between the square, planar bases 50, 
52. Pyramid 48 is capped by a cylindrical portion 54 having a rounded tip 
56 and arranged extending at an end 58 from base 52 and away from surface 
32 of web 28 in order to permit greater penetration at a given 
cross-section area into a recess formed in an associated pulley by the 
projection 34'. The advantage of this embodiment, therefore, is the 
increased potential penetration, inasmuch as the length of the projections 
such as projection 34 is limited by the slope of the walls of pyramid 42 
necessary to permit belt 26 to flex around a desired small diameter 
without projections 34 interfering with one another. 
When made for tracking purposes only, the projections 34, 34' can be 
staggered from column to column so as to form a nonsymmetrical matrix (not 
shown). 
One embodiment of a positive engagement drive arrangement according to the 
present invention is shown in FIG. 4 wherein a pulley 60 has a shaft 62 
forming an axis of rotation and is provided with at least one, and 
preferably the illustrated plurality, of channels 64 arranged extending on 
an outer surface 66 of pulley 60 in directions substantially parallel to 
the axis of rotation of pulley 60 and to each other for engagingly 
receiving the projections 34, and forming positive drive means for 
advancing, forward or backward, the associated belt 26. 
In addition to creating a more efficient belt drive, the arrangement shown 
in FIG. 4 will cause the belt 26 to move as a direct function of the 
angular velocity of rotation of pulley 60, making the system useful for 
timing functions. Alternatively, the pulley 60 can be a return or idler 
pulley and be driven as a function of the speed of the belt 26, making 
possible timing belt arrangements. 
FIG. 5 of the drawing illustrates a pulley 68 rotatable about shaft 70 and 
provided with a symmetrical matrix 72 of sockets 74 in the outer surface 
thereof. The sockets 74 are arranged for engagingly receiving projections 
34, 34' of a belt 26. By this arrangement, a belt 26 simultaneously can be 
positively trained, or tracked, and advanced by rotation of pulley 68 
about the axis of rotation thereof. The size and spacing of the sockets 74 
will be matched to the associated projections 34, 34' being used. 
Also shown in FIG. 5 is a metal layer 75 disposed on surface 28 of belt 26. 
The layer 75, which can be bonded to belt 26 in a suitable known manner, 
can be, for example, a flexible sheet of steel or stainless steel of say, 
0.010" to 0.040" thickness. This feature is particularly advantageous when 
using belt 26 to convey food (not shown) and the like, in which case the 
diameter of pulley 68 preferably is about 1" to each 0.001" thickness of 
layer 75 to assure a suitable slow belt speed. 
Referring now to FIGS. 6 and 7, a pulley 76 is shown which is rotatable 
about a shaft 78 defining an axis of rotation and has a generally 
cylindrical outer surface 80 extending a predetermined length along the 
axis of rotation of pulley 76. A plurality of substantially parallel and 
coextensive annular rings 82 are provided on surface 40, the outer 
peripheries 84 of which rings 82 are contoured to fit between the 
projections 34, 34' provided on a belt 26 according to the invention. In 
this manner, the rings 82 form grooves for receiving the projections 34, 
34' in such a manner as to cause positive tracking of the associated belt 
26, with it being appreciated that the spaces between the rings 26 are 
recesses relative to the surface 32 of the belt 26. 
FIG. 8 shows a positive drive and tracking arrangement according to the 
invention wherein a pulley 86 rotatable about an axle or shaft 88 is 
provided on the outer surface thereof with circumferentially arranged 
teeth 90 arranged forming a sprocket on the associated pulley 86. These 
teeth 90 engage with the projections 34 to positively drive an associated 
belt 26. While not specifically illustrated, it will be appreciated that 
teeth 34' could also be used with pulley 86. In addition, the sprocket 
teeth 90 can be disposed between the annular rings 82 as described above 
in conjunction with FIGS. 6 and 7 to permit positive tracking of the belt 
26 as same as being driven by teeth 90. The latter are necessarily 
arranged in the area normally provided as a groove or recess for receiving 
the projections 34, 34'. 
FIGS. 9a and 9b illustrate an alternative system 92, 92' according to the 
invention wherein cogs or projections 94, which can be in the form of 
projections 34, 34', for example, are provided on an outside surface 96 of 
a belt 98, 98', so as to function as a friction increaser for a load L 
disposed on belt 98, 98', and/or permit a positive drive and/or belt 
training arrangement wherein belt 98, 98' passes over idler pulleys 100, 
and projections 94 engage in grooves, channels, or sockets provided in a 
recessed drive pulley 102, 102' which can be similar to the pulleys 
described above. In this manner, a belt provided with cogs only on its 
outer surface can take advantage of the positive tracking/drive features 
of the invention. 
Pulleys 100 can be very small, for example, only 11/2" in diameter. Belt 
98' is shown as supported on a top run thereof by a slide bed 102. 
Alternatively, a plurality of idler rollers (not shown) could be employed 
in place of bed 103. The arrangement of drive pulley 102' has the 
advantage of substantially 180.degree. surface contact with the associated 
belt 98'. 
Alternatively, a belt 104 as seen in FIG. 10 can be provided with 
projections 106, 108 on both of its planar surfaces 110, 112, 
respectively, so as to interengage with opposed pulleys 114, 116 arranged 
for guiding belt 104 along any desired path. 
Provision of projections such as those designated 106 and 108 on each of 
the oppositely facing surfaces of a conveyor belt permits as well the use 
of the belt for both positive drive and/or tracking according to the 
invention, and for providing a friction increaser surface for a load in a 
manner similar to that of the embodiment illustrated in FIG. 9. 
Further, as shown in FIG. 11, projections 34, 34' can be staggered in 
adjacent columns 38 to form a nonsymmetrical matrix for tracking purposes 
only. 
FIG. 12 is a view similar to FIGS. 4 and 5, but showing how a pulley 118 
rotatable about a shaft 120 can have a length of a belt 26 affixed to at 
least a central portion of the pulley surface 122 for driving and/or 
tracking a mesh belt 124. The amount of surface 122 covered by projections 
such as 34, 34' may vary as desired. 
As can be readily understood from the above description and from the 
drawing, an endless conveyor system using belt projections formed and 
arranged according to the present invention permits positive belt training 
and/or belt/pulley advancement, including reversal, in a simple yet 
efficient manner. Further, the belt can be used for timing purposes as 
well as for transmission functions, since the positive advancement feature 
will cause a return or idler pulley provided with channels, teeth, or 
sockets to be rotated by the belt as a function of the angular rotation of 
the drive pulley of the system. 
Most importantly, the belt tracking and/or driving system according to the 
present invention permits use of end pulleys of very small diameter down 
to one inch, for example, to be used while still obtaining a belt 
conformity about the pulley of substantially 180.degree.. While the number 
of tracking grooves formed on a pulley either by recesses or raised rings 
can vary, it has been found satisfactory to provide such grooves across 
approximately one-third of the length of a pulley. Further, the present 
invention permits use of high friction carrying belts of load carrying 
ratings starting at, for example, 120 pounds per inch of width of the 
belt. 
Although the present invention has been described above in terms of 
presently preferred embodiment, it is to be understood that such 
disclosure is by way of example only and is not intended to be considered 
as limiting. Accordingly, it is intended that the appended claims are to 
be interpreted as covering all alterations and modifications as fall 
within the true spirit and scope of the invention.