Conveyor belt module drive surfaces for mating with sprocket drive surface in the hinging region

This invention solves a problem encountered in driving conveyor belts where mating belt drive engagement surfaces and sprocket drive surfaces interact to cause wear and to force the belt away from the sprocket. Thus, various shaped modular belt links, provided in accordance with this invention to fit into various conveyor belt configurations, have drive structure appendages extending from cylindrical structure about the pivot rod journalling aperture to form drive surfaces which enter and leave mating sprocket drive channels, with wall surfaces formed between adjacent sprocket teeth in a substantially parallel drive relationship to avoid radially directed forces that drive the belt away from the drive sprocket. Trapezoidal shaped drive surface appendages from the links extend from a generally cylindrical body about the pivot rod in a preferred embodiment. Sprocket drive teeth engage respective ones of two side by side such cylindrical bodies on different end to end links for driving the belt in opposite directions. The cylindrical body has walls of differing thicknesses on opposite sides where intersected by a plane parallel to the belt.

TECHNICAL FIELD 
This invention relates to the structural characteristics of conveyor belt 
modules, and more particularly to interacting module and sprocket drive 
surfaces coacting at the hinging joints. 
BACKGROUND ART 
Modularized conveyor belts and accompanying drive systems are well known in 
the art, and are found with modules of various characteristics that are 
coupled together and articulated by means of pivot rods so that they can 
be endlessly moved by means of rotatable sprockets. The trend in the art 
is to produce modules of various shapes and interactions for achieving 
various advantages in operation. It is a general problem in the art to 
provide modular elements that are easily made, such as by molding from 
plastic, and yet present superior operating characteristics particularly 
in the critical sprocket and module driving surface interface. Thus, one 
objective of this invention is to provide improved simplified modular 
elements and conveyor belt drive systems embodying modular elements. 
A critical operational region in conveyor belt systems driven by a sprocket 
at the hinged joints is caused by the hinging driving interface between 
the belt modules and the relatively moving rotating sprocket drive 
surfaces. The prior art has many different configurations of sprocket and 
belt structure with special driving surface features. However, the prior 
art hinge region drive surfaces present operational disadvantages. In 
consideration of the driving interface design of prior art conveyor belt 
systems, some of the critical operating conditions involved are the wear 
at interfacing drive surfaces, the ability of the belt to articulate 
smoothly over small diameter sprockets, the performance of the belt over 
the range of no-load to full-load conditions, the energy or friction 
losses of the drive system, the ability to run at various speeds, freedom 
from vibration and noise, and the ease of replacing worn surfaces or 
parts. In particular the interface between sprocket and module surfaces 
generally react during the hinging acting to urge the belt away from the 
sprocket to introduce significant problems in controlling belt slack and 
tension and wear at the sprocket-hinge interface surfaces. No known prior 
art belt system has been completely satisfactory over such a comprehensive 
range of desiderata. Thus, it is a further objective of this invention to 
provide improved belt drive systems advantageous with respect to these 
foregoing requirements, which is useful for a variety of belt module 
configurations. 
The significant uncorrected problem that has surfaced in many of the prior 
art sprocket to belt drive interface systems is that the motion of the 
sprocket and the interaction of the drive surfaces tend to generate forces 
which drive the belt away from the sprocket. This visibly reacts in a 
manner similar to slack in the unloaded system, and if the belt is 
tightened to remove slack, then the operating friction becomes excessive, 
without correcting the urging forces, thereby causing inefficient 
operation with more wear on the drive surfaces. Other attempted solutions, 
such as counteracting forces applied to the belt or limiting guide 
brackets to limit belt movement away from the sprocket are not 
satisfactory solutions. Accordingly a still further objective of this 
invention is to provide an improved conveyor belt system wherein 
interacting belt-sprocket drive forces that tend to drive the belt away 
from the sprocket are avoided. 
Other objects, features and advantages of the invention will become 
apparent from the following description taken with the accompanying 
drawings and claims. 
DISCLOSURE OF THE INVENTION 
A modularized conveyor belt is formed from variously shaped modular 
members, illustrated for example in a wishbone-shaped embodiment defining 
three fingers or link ends respectively as a stem extending in one 
direction and two bifurcated fingers extending in the opposite direction 
to define drive surfaces containing journalled apertures alignable along 
pivot axes at opposite ends of the modular members. The various modules 
for which this invention is directed have in common drive surfaces in the 
hinging region which move during articulation and thus produce a dynamic 
interface with mating sprocket drive surfaces. These modular members thus 
have disposed about pivot rods side-by-side interfacing drive members 
extending alternately in opposite directions about pivot rods toward 
respective end to end articulating modules. Different configurations 
permit links to be articulated at opposite ends about a pivot rod, or 
groups of such links held together in modular units of predetermined width 
across the belt by means of integral interconnecting structure such as 
connecting crossbeams, usually centrally positioned along the length of 
the modular elements and disposed normally to the direction of belt 
travel. Typically the belt loading surface of one class of modular links 
or modular units terminates in a plane, which could be a suitably 
apertured flat sheet surface, for example, or alternatively an open 
gridwork arrangement. Another class of modular members may have non-planar 
belt loading surfaces. 
Spacings between adjacent parallel pivot rod axes (pitch) formed by the 
module member or modular sections may vary, but typically could be as 
little as about one-half inch (1.27 cm) for smaller modules, which need be 
addressed as well as larger modules. In such modules, drive tooth surfaces 
typically extend downward from the bottom belt surface about 0.1 inch 
(0.25 cm) for a 0.5 inch (1.3 cm) pitch. This invention is not pitch 
limited. A preferred wishbone pitch is 0.6 inch (1.5 cm). In any event, a 
typical drive surface afforded by this invention could comprise a 
generally trapezoidal drive tooth shape with planar sidewalls extending 
from generally cylindrical surfaces disposed about the pivot rod to form 
journalling apertures. 
Belt systems in general are driven by a rotary sprocket wheel with 
peripheral teeth entering mating channels of the modular members to 
interface with interacting module drive surfaces. Thus, a drive force 
reacts on the pivot rod through generally cylindrical structure, which 
constitutes the pivot rod journals at opposite ends of the modular 
members. The entry angle of the sprocket drive teeth with respect to the 
two substantially parallel interacting drive surfaces of module links 
afforded by this invention accommodates entry into and exit from the 
sprocket wheel or drive contact without interference. Thus, two 
substantially planar surfaces are mated with substantially parallel 
dynamic movement for both entry and exit of sprocket driving teeth into 
the belt configuration. The respective planar drive surfaces are disposed 
generally radially with respect to the sprocket wheel drive axis for 
mating in movement over a predetermined sprocket arc. The module members 
form sprocket channels or notches for drive teeth to enter or leave the 
belt with the sprocket and module planar teeth surfaces substantially 
parallel so that radial forces tending to drive the belt away from the 
sprocket are avoided. 
To facilitate better driving forces when the sprocket drive tooth surfaces 
enter the sprocket drive notch of the belt without any interference or 
substantial surface wear, the link end pivot rod journalling surfaces at 
the drive interfaces may have a different radius center than the opposite 
surface. Thus, the two walls formed about the pivot rod at the module link 
finger ends in a plane parallel to the belt have different thicknesses to 
produce a thinner inside edge surrounding cylindrical wall positioned 
inwardly in the driven link in the driving direction than the 
corresponding outside driven edge wall thickness directed away from the 
driven link ends. This avoids any interference, scrubbing or wear on the 
sprocket teeth from the adjacent interdigited link ends of the adjoining 
modular section during dynamic reaction with sprocket drive teeth at the 
articulation joint. 
Accordingly the modular belt conveyor system drive interface between the 
module links and the sprocket interengage in movement onto, about and away 
from the rotating sprocket wheel to produce substantially only 
circumferentially oriented drive forces. The interface contact forces from 
the sprocket wheel engaging the belt to the driven link are applied in a 
direction substantially tangential to the sprocket wheel thereby avoiding 
the undesired radial forces produced in the prior art drive interfaces 
that tend to urge the belt or module away from the sprocket wheel. This 
keeps noise, friction, vibration and wear at a minimum and maintains the 
belt in good circumferential contact with the sprocket wheel under all 
conditions from no-load to full-load.

THE PREFERRED EMBODIMENTS 
Now with reference to FIG. 1, it is seen that the belt module embodiment 15 
is formed of four wishbone shaped basic modular links 16, 17, 18, 19, held 
in place by a substantially longitudinal transverse rod support structure 
20 or connecting beam integrally joining the modular members 16, 17, 18 & 
19 to provide a multi-linked modular unit. Typically the modular unit is 
molded from plastic and the connecting beam need not bear weight or act as 
a structural element such as drive member, but forms the individual links 
into a modular unit. As seen from the end view of FIG. 2, the top of the 
belt 25 forming the working surface is generally flat or planar, and drive 
surfaces extend from the underside as teeth 26. Axial apertures 27 formed 
in the module fingers 30, 31, 32 receive and journal pivot rods in fixed 
alignment along two parallel pivot rod receiving axes (28). 
The belt edge wishbone link 19 of the module 15 forms a retaining cap 29 
for preventing axial movement of the pivot rods out of the belt toward the 
right. The cap 29 is resiliently supported by elastic plastic arm 33 so 
that it may be flexed away from axis 28 to insert or remove a pivot rod 
along axis 28. 
Each wishbone module link 16, 17, etc. has a stem portion or finger 31 with 
the pivot rod journalling aperture 27 having an axis (28) normal to a 
first plane 35 passing through the stem portion 31. The stem portion is 
bifurcated at the location 36 near the connecting beam 20 to extend into 
two branches, link ends, or fingers 32, 30, which also define pivot rod 
journalling apertures 27, and which lie in planes 36, 37 parallel to and 
on opposite sides of plane 35. These wishbone module links 16, 17 are 
assembled with the alternating stems 31, 38 pointing in opposite 
directions and with appropriate spacings 39 between the fingers of 
slightly greater width than the width of the fingers for interdigitating 
link end fingers of like modular units 15 in place in end to end 
relationship. 
As seen from FIG. 3, a peripheral arc 40 of a rotary sprocket drive wheel 
41 has a plurality of notches or spaces 42, 43 formed between adjacent 
teeth 44, 45, 46 about the drive sprocket periphery. Thus, looking into 
the left end of FIG. 1, the modular section 15 is viewed similar to the 
FIG. 2 profile 25 existing at a sprocket wheel engagement position 
somewhere along the length of the modular section 15. The belt module 
tooth 26 thus mates into the sprocket notch 43 and the sprocket 4 drives 
the belt formed of end to end modules 25, etc. in the direction of arrow 
48. The access notches 49 in the teeth (46) accommodate the transverse 
connecting beam 20 structure of the modular units 15 in a non-contact 
relationship to avoid interference, as seen from the incremental movement 
line segments 47. 
Driving surfaces 52, 53 on opposite sides of notches (43) in the sprocket 
wheel 41 are substantially radially disposed from the axis of rotation of 
the sprocket wheel 41, thereby presenting substantially planar surfaces. 
The sprocket teeth 44, 45, 46, etc. pass through access apertures on the 
bottom surface of the assembled belt end-to-end modular sections 15 in a 
manner later shown. Mating surfaces 55, 56 on the modular unit teeth 26 of 
the belt thus mate into the sprocket notches (43) between the teeth on the 
sprocket wheel 41 and only the surface 55 interacts as a driving surface. 
(The mating surfaces are not shown in touching contact in FIG. 3 to avoid 
clutter.) 
The particular parallel surface structure of the interengaging drive 
surfaces 52, 55 herein provided assures minimal frictional losses, quiet 
and vibrationless entry and exit of the belt teeth 26 into the sprocket 
notches 43, smooth transmission of power from the sprocket drive wheel to 
the belt, and optimal entry and exit behavior of the belt teeth 26 with 
the sprocket drive notches. The drive power is thus transferred without 
inducing any substantial radial drive forces tending to force the belt 
either toward or away from the sprocket wheel periphery. Thus the belt 60 
is conveyed substantially tangentially to the periphery of the sprocket 
wheel 41, with all drive forces urging the belt in the direction 48, as 
seen better from the view of FIG. 4. The belt module drive members 26 are 
substantially immersed in the notches 43, etc. up to, or just above, the 
diameter of the pivot rods and pivot rod journalling apertures 27. 
The incremental postures of the belt tooth interface surfaces during the 
critical entry (or exit) phases as the sprocket rotation progresses over 
the arc 40 is represented for a set of incremental positions by the sets 
of position lines 61. By means of the generally trapezoidally shaped 
region 66 formed by the belt module drive appendages extending away from 
each pivot rod journalling aperture 27 and surrounding cylindrical body to 
form the belt drive teeth 26, the belt presents substantially planar 
contact interaction surfaces 55, 56. Thus, as seen in sprocket notch 42, 
the drive surfaces interact upon belt tooth 26 entry so that the 
respective belt and sprocket drive surfaces are parallel and thus avoid 
any driving forces tending to move the belt radially from or towards the 
rotation axis of the sprocket wheel 41. 
As may be seen in FIG. 3A, the opposite walls 57 and 58 of the body 54 
about the pivot pin journalling aperture 27' are of different thickness. 
Thus, the cylindrical curvature of the wall 57 by the radial arrow to 
provide wall 57 to the left is generated from center 60 of the cylindrical 
aperture 27' lying on axis 59R as noted by the radial arrow extending to 
wall 57. The thinner wall 58 to the right is generated similarly from 
offset center 62 on axis 59L as noted by the radial arrow extending to 
wall 58. The pivot rod journalling aperture 27' is generated from center 
60 as shown by the third radial arrow. This difference in wall thicknesses 
reduces the tendency of the surface 56 on the belt drive tooth 26 to scrub 
against the mating notch (43) surface 53 of the sprocket wheel during the 
dynamic movement of the interengaging belt and sprocket wheel. The 
trapezoidally shaped tooth appendages 26 on the belt modules extend 
outwardly from a substantially cylindrical integral structure 54' about 
the pivot pin journalling aperture 27, with the contact surface 55 
entering the sprocket notches 42, 43, etc. with parallel contact surfaces. 
Because of the thinner wall 58, the non-drive surface 56 enters and leaves 
the sprocket notches 42, 43, etc. without scrubbing or interference that 
causes wear or radial forces urging the belt modules 25, etc. away from 
the sprocket. 
The wishbone module elements and sections 15 have a preferred pitch of the 
order of a 0.6 inch (1.3 cm) between the axes 28 of the pivot rods so that 
a belt can make very sharp turns about a sprocket of less than three 
inches (7.6 cm) in diameter and having sixteen sprocket teeth. Four and 
one-half inch (11.4 cm) diameter and six inch (15.2 cm) diameter sprockets 
having twenty-four or thirty-two sprocket teeth also are used where room 
is available for less sharp turns. Thus, the distinct advantages are 
attained by this invention of (1) less tendency for the belt to push away 
from the sprocket with corresponding advantage of simplicity in adjusting 
belt tension and reduced friction and energy, (2) long life because of 
reduced scrubbing and wear, and (3) low drive energy with very little 
vibration and noise caused in the drive mechanisms. 
The invention is characterized by hinge driven modular conveyor belt 
forming links. A preferred embodiment integrally carries drive tooth 
surfaces extending downwardly from the belt surface from a generally 
hollow cylindrical link end body defining a pivot rod journalling 
aperture. Thus, opposite drive and non-drive surfaces are presented for 
interacting with mating drive surfaces of sprocket wheels at opposite 
sides of notches formed between drive sprocket teeth. The belt teeth are 
preferably shaped as trapezoidal appendages integrally extending from the 
generally cylindrical link end body forming a pivot rod journalling 
aperture. The drive tooth surfaces on the belt and the drive surfaces on 
the sprocket are disposed so that the belt teeth enter and leave sprocket 
drive channels between adjacent teeth with the opposing belt and sprocket 
surfaces in substantially parallel relationship to produce tangential 
driving forces and to avoid any radial driving forces tending to push the 
belt away from the sprocket. 
In FIG. 3A, a characterizing feature is illustrated, namely that opposite 
cylindrical sidewalls 57, 58 have differing thicknesses in the plane 68 
passing parallel to the belt thereby to reduce the chances of frictional 
contact during articulation when sprocket drive teeth engage the 
sidewalls. 
In FIGS. 3B and 3C the operational relationships of the thinner wall 
adjoining surface 56 and thicker wall adjoining surface 55 are 
illustrated. The phantom view modules 25' illustrate a pivot rod at axis 
63 with respect to the modules 25, 25'. FIG. 3B shows non-articulated belt 
modules and FIG. 3C shows the belt modules 25, 25' articulated. 
The end to end connected and interdigitized modules 25 and 25' are 
alternately positioned with thicker walls 58 and thinner walls 57 facing 
in opposite directions. Non-drive surfaces 67, by means of the 
thinner-thicker wall structure 58, 57 are offset from the drive surfaces 
(64L and 64R for module 25' and 65L, 65R for modules 25), and thus assure 
that no frictional contact or interference occurs from the sprocket drive 
teeth during the dynamic articulation cycle. 
To drive the belt to the right, the drive surfaces 64L and 65L would be 
contacted by the sprocket drive teeth. Conversely, when driving the belt 
to the left, drive surfaces 65R and 64R are contacted by the sprocket 
teeth. 
As seen in FIG. 5, the modular sections 15 are held together end to end in 
a belt configuration by means of pivot rods 14. The sprocket drive teeth 
46, which are notched to straddle the link connecting beams 20 (FIG. 3), 
are shown in their drive relationship so that drive forces are effected 
upon the pivot rod in the articulation joint region by means of the 
intervening wishbone member drive tooth structure described in FIGS. 3B 
and 3C. Thus, the non-contact surfaces 67 are distinguished from the drive 
surfaces 64, 65. 
The belt embodiment of FIG. 6 is formed by the individual V or Y shaped 
links 70 without the connecting beams employed in the previous embodiment. 
Although the connecting beam structure gives more unity of modular member 
action transverse to the belt and permits larger modular units to be made 
and handled, it is not a necessary feature. The offset drive and non-drive 
surfaces are not shown, and are not necessary for drive purposes. However 
they permit sprocket teeth 76 to be inserted and withdrawn for 
articulation with less frictional scrubbing and interference. The 
invention is thus generally characterized by modular link belts with drive 
surfaces in the hinging region for forceful contact with driving surfaces 
at a critical driven one of two side by side link ends. 
From the exploded view of FIG. 7, it is seen that the modular sections may 
form a belt of desired width in bricklayered fashion by means of an 
end-cap-less modular section 71. The belt edge modular sections 15' of 
this embodiment have male pivot rod retention posts 72 inserted into the 
adjacent wishbone journalling aperture 27 to abut the pivot rod 14. As in 
the previous embodiment of FIGS. 1 and 5, the flexible retention ar 33 
permits the retention posts 72 to be moved aside for entry or removal of 
the pivot rods 14. 
The right end modular section 15" may be different in length from the left 
end modular section 15' on a row of modules. With various module lengths, 
the bricklaying pattern can be realized. However identical modules can be 
used on either belt edge with 180 degree rotation to fit on the opposite 
ends. The end-cap-less modules 71 also can be made of various lengths to 
fill the space between the endcapped belt edge units 15', 15". Thus, with 
only a few basic wishbone modular section configurations the belts may be 
bricklayered, and belts of various widths may be constructed of a minimum 
of only two basic modular section configurations. 
In the offset I link belt of FIG. 8, the links 75 are shown individually 
assembled, but these may be grouped with a cross connecting beam. Such 
belts present drive surfaces 77 which as aforesaid are constructed for 
improved performance in accordance with the principles of this invention. 
It has been shown that the various belt module configurations and 
associated drive systems afforded by this invention have advanced the 
state of the art. Accordingly those features of novelty setting forth the 
nature and spirit of the invention are defined with particularity in the 
following claims.