CA1042827A - Belt conveyor - Google Patents

Abstract

BELT CONVEYOR

ABSTRACT OF THE DISCLOSURE
A belt-type conveyor having an endless belt supported on a pair of spaced end rollers. The upper reach of the belt is adapted to have articles supported thereon for transporting thereof. A drive system is interconnected to both end rollers to simultaneously rotatably drive same, which end rollers in turn drive the belt. This drive system permits the upper reach of the belt to be maintained relatively free of tension so that the upper reach will readily conform to a guide struc-ture which is positioned thereunder for slidably supporting same. The conveyor is particularly suitable for use as an inclined conveyor to permit lifting of articles on the upper belt reach, which upper reach can be bent upwardly from a horizontal position without requiring top guide rails or other hold-down devices.

Description

10~2827 FIELD OF THE INVENTION
This invention relates to an improved belt-type conveyor and, in particular, a conveyor suitable for use as an inclined conveyor.
BACKGROUND OF THE INVENTION
Belt-type conveyors are utilized extensively for trans- `
ferring articles or objects from one station to another. In -~
such conveyors, there is normally provided an endless belt trained around a pair of end rollers, with additional inter-mediate idler or tensioning rollers also being provided. The upper reach of the belt is normally utilized for supporting the articles being transferred. In some conveyors, normally referred to as horizontal belt conveyors, the upper belt reach extends substantially horizontally and thus merely transfers the objects between two different horizontally -.spaced stations. Other conveyors, normally referred to as I an inclined conveyor, have at least a part of the upper belt ! reach extending upwardly at an angle with respect to the horizontal so as to permit a vertical lifting of the articles as they are transported between two working stations.
In these known conveyors, the drive is normally con-nected to only one of the end rollers so that the belt is thus under a substantial tension in order to effect operation of the conveyor. Because of the tension in the belt, it is necessary for the conveyor to be provided with complex alignment structure, associated with both the belt and the roller, so as to permit proper tracking of the belt. If the rollers and belts are not properly aligned, then the tension in the belt causes the belts to continually move sidewardly of the rollers so that the side edges of the belt rub against ~ ' .

lQ4Z8Z7 the guide structure, thereby resulting in excessive wear.
The tension in the belt thus makes the overall conveyor more complex by requiring costly alignment structure, and additionally makes set-up and operation more difficult in view of the necessity of having this structure precisely adjusted. Since this is difficult to accomplish, undesira-ble wear of the belt is normally encountered during usual ;~ - `
operation of such conveyors.
In addition to the above problems, belt conveyors of the inclined type possess still further structural and operational disadvantages. Particularly, in inclined conveyors wherein the upper belt reach has a portion projecting horizontally and a further portion inclined upwardly, it is necessary to provide guide structure throughtout the curve (the junction between the horizontal and inclined portions) in order to maintain the desired curvature of the upper belt reach.
Absent this guide structure, which normally comprises guide rails disposed for engagement with the upper side edges of the belt, the proper curvature of the belt can not be main-tained in view of the large tension which exists in the belt.
The use of these top guide rails is, however, undesirable in ~ `
view of the excessive rubbing and wear which they cause on the belt. In addition to the top guide rails, it has also -often been necessary to provide an additional control roller at the curve in order to maintain the belt in the desired path, but this control roller greatly restricts the applicability of the conveyor for many uses. ;
Because of the excessive belt tension required in these "
known belt conveyors, a problem of bowing of the belt across the width thereof has also been experienced. To overcome this .. . . , . , . . . .. ~ . .. . . . . . . . .

problem, it has been conventional to provide cross rails on the belt so as to strengthen same and prevent bowing. This not - only increases the cost and complexity of the belt, but also increases the complexity of driving and controlling the belt.
Accordingly, it is an object of the present invention to provide an improved belt conveyor which overcomes the above-mentioned disadvantages. More specifically, the belt conveyor -~
of this invention includes a drive arrangement which is connected to and simultaneously drives both of the end rollers which support the belt so that the belt is maintained with little, if any, tension therein during operation of the system.
The belt conveyor of this invention includes a housing, first and second elongated rollers supported on the housing for rotation about substantially parallel horizontal axes, an endless flat belt supported on and extending between said rollers, said belt being of substantial width and having an outer surface adapted to support articles thereon as they are being moved by said conveyor, and a drive device interconnected to one of said rollers for moving said belt. The second roller is displaced horizontally from and vertically above said first roller. The belt has a non-straight upper reach which extends between said first and second rollers, said upper reach including first and second elongated belt portions which extend at a substantial angle with respect to one another, said first belt portion being positioned adjacent said first roller and extending outwardly therefrom in a direction which is generally toward said second roller, said second belt portion being positioned adjacent said second roller and extending outwardly therefrom in a direction which is generally toward said firat roller, said second belt 30~ portion being substantially straight and inclined at a substantial . ~"

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angle with respect to the horizontal, and a curved bel~t portion interconnected between said first and second belt portions. Guide means are mounted on said housing and disposed for guidably sup-porting the upper reach of said belt as it extends between said first and second rollers, said guide means engaging the undersur-face of said upper reach so that as it extends between said first and second rollers it is supported solely by the guidable engage-ment of the undersurface thereof with said guide means. The drive device causes simultaneous rotation of said first and second ~ -rollers in the same rotational direction for causing movement of i~
the upper reach of said belt in a direction from said first roller toward said second roller so that articles supported on ~ ;
said upper reach are moved upwardly by said second belt portion.
The drive device includes a common drive motor and a power train ;~
drivingly connected between said motor and said second roller for ` causing rotation thereof at a selected peripheral velocity. The power train is also drivingly connected between said motor and said first roller for causing rotation thereof at a peripheral velocity which is at least equal to said selected peripheral velocity, whereby the upper belt reach is substantially free of tension and is maintained in a desired non-straight configuration due to said upper reach being supported solely by said first and second rollers and said guide means so that said upper belt reach does not require the use of any guiding structure disposed in engagement with the upper surface thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of an inclined conveyor accord- ~-ing to the present invention. ~ ' Figure 2 is a side elevational view taken along the line II-II in Figure 1.

Figure 3 is an enlarged, fragmentary sectional view taken -" ':, ., :~
'~ ' ,",': ,' "' ~ ' 1~42827 along line III-III in Figure 2.
Figure 4 is an enlarged, fragmentary sectional view taken along line IV-IV in Figure 2.
Figure 5 is a perspective view of a horizontal conveyor according to the present invention.
Figure 6 is a side elevational view taken along the line VI-VI in Figure 5.
Certain terminology will be used in the following descrip-tion for convenience in reference only and will not be limiting.
For example, the words "upwardly", "downwardly", "leftwardly"
and "rightwardly" refer to directions in the drawings to which reference is made. The word "forwardly" refers to the normal direction of movement of articles by the conveyor belt, which movement occurs from right to left in Figures 1 and 2. The words "inwardly" and "outwardly" refer to directions toward and away from, respectively, the geometric center of the con- -veyor and designated parts thereof. Said terminology includes the words specifically mentioned, derivatives thereof and words of similar import.
DETAILED DESCRIPTION
Figures 1 and 2 illustrate a belt conveyor 11 which includes a horizontal conveyor section llA and an inclined conveyor section llB. The conveyor 11 has a housing 12 on which is supported an endless conveyor belt 13. The housing is, in the illustrated embodiment, supported on an adjust- -able scissor lift 14 so that the position of the conveyor ~
can be selectively adjusted. -The housing 12 is illustrated as being of an upwardly opening boxlike configuration and includes a bottom wall 16 and a pair of upwardly projecting parallel sidewalls 17 and 18.

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The opposite ends of the housing are closed by a front ~ -wall 19 and a rear wall 21.
The endless belt 13 is supported on and extends between a pair of axially elongated cylindrical end rollers 22 and 23, which rollers extend between the sidewalls 17 and 18 and are rotatably supported thereon, as by conventional bearings. The end rollers 22 and 23 are disposed with their ~ -axes extending in parallel horizontal relationship. Belt 13 has upper and lower belt reaches 24 and 26, respectively, which reaches extend between the rollers 22 and 23. The upper belt reach 24 includes a horizontal belt portion 27 which is adjacent the inlet end of the conveyor, an inclined belt portion 28 which is at the discharge end of the con- ;~
veyor, and an intermediate curved belt portion 29 which joins -the horizontal and inclined portions 27 and 28, respectively.
The horizontal belt portion 27 is slidably supported on a pair of horizontally elongated guide rails 31 which, as shown in Figure 3, are of an L-shaped configuration and are fixed to the sidewalls 17 and 18. The inclined belt portion 28 is similarly slidably supported by a pair of elongated guide rails 32 which are inclined upwardly at the desired inclination. The guide rails 32, like the guide rails 31, -are of an L-shaped cross section and are fixedly secured to the opposite sidewalls 17 and 18. -As described above, the upper left reach 24 is supported solely by the guide rails 31 and 32, which guide rails support the upper belt reach solely by slidably engaging the underside of the belt. Thus, the complete upper reach 24 does not have any guide structure disposed in engagement with the upper surface thereof, and in fact the curved belt portion .

1~4Z8Z7 29 is free of any guiding support.
The lower belt reach 26 is maintained in a curved configuration which results from the belt being maintained in a suspended condition over a major portion of the length thereof. However, a pair of cylindrical idler rollers 33 and 34 are rotatably supported on the sidewalls -of the housing and are positioned for engaging the lower belt reach. The rollers 33 and 34 are disposed closely ,. .
adjacent the end rollers 22 and 23, respectively, whereby they ensure that the belt extends around the end rollers and is driven by a motor 36, such as an electric motor.
The motor 36 is positioned within the housing, as by being mounted on the bottom wall 16 beneath the inclined portion of the belt. Motor 36 has the shaft 37 thereof pro- ~ -jecting outwardly from one side of the housing, which motor shaft 37 has drive sprockets 38 and 39 fixedly secured thereto. Drive sprocket 38 is in driving engagement with a first chain 41, which in turn is engaged with a driven sprocket 42, the latter being nonrotatably secured to the shaft of the end roller 22. A second chain 43 is in engagement with the other drive sprocket 39, which chain 43 is in turn engaged with a further driven sprocket 44 which is nonrotatably secured to the end roller 23. In this embodiment, the sprockets 38 and 39 are of identical diameters, and the -sprockets 43 and 44 are also of equal diameter, whereby the motor 36 causes simultaneous driving of the two end rollers 22 and 23, which end rollers are also of equal diameter and are thus driven with equal peripheral speeds.
The drive structure, namely the sprockets and the chains, .::
30 are positioned adjacent but exteriorly of the sidewall 17. -,.", ~ ,. ..
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They are enclosed within a suitable cover or shroud 46 which is fixedly secured to the sidewall 17.
.To ensure that the end rollers 22 and 23 both cause :.a simultaneous driving of the belt 13, and to positively :
prevent slippage of the belt on either of the end rollers, .
the belt is driven from the rollers 22 and 23 by means of a toothed driving connection. This toothed driving connection includes a drive gear 47 (Figure 4) fixedly associated with each of the end rollers 22 and 23. This drive gear is in turn maintained in meshing engagement with a toothed gear rack 48 which is fixed to and extends throughout the ~ .
length of the belt 13.
-In the illustrated embodiment, as shown in Figure 4, each roller 22 and 23 has an annular recess 49 formed therein, : :
and the bottom of this recess 49 has teeth formed thereon, which teeth form the drive gear 47. The gear rack 48 pro-vided on the belt 13 projects downwardly from the undersurface 51 of the belt and projects into the recess 49 so as to be in meshing engagement with the drive gear 47. This construc-tion not only provides a positive driving connection between the belt 13 and each of the rollers 22 and 23, but it also provides an effective alignment structure which prevents the belt from slipping or moving sidewardly with respect to the rollers 22 and 23. This structure thus ensures that the belt tracks properly over the rollers and does not move side-wardly so as to unduly rub against the housing sidewalls.
While a positive (for example, a toothed) driving connection between the belt 13 and the rollers 22 and 23 . -is preferred so as to positively prevent slippage between the belt and the rollers, nevertheless such a positive driving ' _ 9_ . . .

. ... -- - . - , . ~

~)428~7 connection is not necessary under all conditions of use.
For example, where relatively light loads are imposed on the conveyor, then the teeth can be eliminated and a fric-tion drive relied upon for driving the belt from the end rollers. The use of the teeth is, however, preferred in most situations where heavy loads are to be transported.
The belt 13 may also be provided with elongated rodlike cleats 52 fixed to the outer surface thereof, which cleats extend transversely across a major portion of the belt width. These cleats are of primary importance when the conveyor is provided with an inclined portion, inasmuch as the cleats assist in holding the objects in position on -the belt as the belt moves upwardly through the inclined -portion. Depending on the type of usage, the angle of inclination, and the nature of goods being transported, the use of such cleats is optional and the cleats may be eli-minated in many use situations.
As shown in Figure 1, a deflector 53 in the form of a resilient plate is secured to the housing across the inlet end thereof, which plate projects downwardly and engages the upper surface of the belt in the vicinity of the end roller 22. This deflector 53 prevents articles which are deposited onto the belt from falling downwardly between the end roller and the housing.
OPERATION
In operation, articles or objects which are to be trans-ported are deposited onto the upper surface of the horizontal belt portion 27. The belt 13 is driven from the motor 36, ~;
whereupon the belt 13 thus moves in the direction of the arrows so that the articles are carried leftwardly to the ' ~'': ' --10-- r~

1~4Z827 :; -curved portion 29 and then upwardly along the inclined portion 28 until reaching the upper end roller 23. At this point, the articles are suitably discharged from the conveyor, as by being deposited into any other suitable apparatus, such as into a bin or onto a further conveyor.
During driving of the belt 13, the motor 36 drives both of the end rollers 22 and 23 in the same rotational direction at the same peripheral speed due to the dual driving connec-tions provided by the chains 41 and 43. Since substantially equal driving forces are imposed on the belt 13 adjacent the opposite ends thereof, which forces are provided by the driving rollers 22 and 23, the upper belt reach 24 is substan- -; tially free of tension as caused by the driving forces. While it is obviously impossible to have zero tension in the belt, since some tension will occur due to the effect of gravity, nevertheless the tension in the upper belt reach is maintained at an absolute minimum. This lack of tension enables the belt to track freely on the rollers without encountering any substantial problem of misali~nment. Further, even if the belt does not track in a straight manner, nevertheless the low tension in the belt minimizes the wear of the belt and prevents any undue wear of the belt due to the edges thereof rubbing against the sidewalls. Even this problem of belt tracking is substantially eliminated, however, when the conveyor is pro-vided with the toothed guiding connection formed by the gear 47 and gear rack 48. This connection functions as an align-ment structure for maintaining the belt properly guided on the rollers 22 and 23, and in addition prevents slippage -between the belt and the driving rollers.
Due to the substantial absence of tension in the upper --11-- -~

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reach of the belt, the upper reach can be guided solely by the guide rails 31 and 32 which engage the horizontal and inclined portions of the belt, respectively. These guide rails 31 and 32 solely engage the undersurface of the belt. The upper surface of the belt, in the upper reach thereof, is totally free of any guide rails or slide surfaces. Further, the curved portion 29 does not require ~-the use of any upper guide rails for maintaining the belt in the desired curvature, so that there is thus no wear of the upper belt surface. The desired curvature of the belt in the upper reach thereof is easily maintained solely due to the proper driving engagement of the belt with the rollers 22 and 23, which driving engagement provides the desired curvature in the upper reach, which curvature is then main- -tained since the upper reach is relatively free of tension.
MODIFICATIONS
While the invention illustrated in Figures 1-4 relates ~-to an inclined conveyor wherein the end rollers 22 and 23 are disposed at different elevations, it will be appreciated that the present invention is also applicable to a horizontal conveyor wherein the upper belt reach is disposed within a single plane which is approximately horizontal. Figures 5 and 6 illustrate such a horizontal conveyor 61 therein, which conveyor has a housing 62 on which a movable endless belt 63 is supported. The housing is formed by opposed substan-tially parallel sidewalls 66 and 67 which are interconnected by substantially parallel and horizontally extending top and bottom walls 68 and 69, respectively. ~-A pair of end rollers 71 and 72 extend between and are rotatably supported on the opposed sidewalls, which end 1042~327 :-rollers are supported for rotation about axes which are parallel and extend substantially horizontally. The end rollers 71 and 72 are disposed in engagement with the conveyor belt 63 whereby the upper belt reach 73 is slidably supported on the upper surface of the top wall 68, whereas the lower belt reach 74 is disposed adjacent but spaced upwardly from the bottom wall 69.
The rollers 71 and 72 are normally of identical dia-- meter and have drive sprockets 76 and 77, respectively, nonrotatably secured thereto. These drive sprockets in turn are driven by an endless driving element 78, specifically a chain, which in turn is driven by a driving sprocket 79 associated with a driving motor 81 which is disposed within the housing, as by being mounted on the undersurface of the top wall 68. This driving arrangement results in a positive driving of both rollers 71 and 72 at equal peri-pheral speeds whereby the upper belt reach 73 can be main--~ tained relatively free of tension.
In this variation, the rollers 71 and 72 are preferably disposed in frictional engagement with the belt 63, which frictional engagement is assisted by providing the rollers with a conventional roughened surface. While the belt and rollers can be provided with a gear-type driving connection therebetween, such as in the embodiment of Figures 1-4, such a toothed driving connection is normally not necessary inasmuch as the loads carried by the upper reach are being moved horizontally so that a smaller driving torque is hence required.
The horizontal conveyor 61 of Figures 5 and 6 has the same advantages as the inclined conveyor 11 described above, .':

~04Z8Z7 in that it eliminates the necessity of complex adjustable alignment structure and also eliminates the problem of undesirable belt wear due to rubbing of the belt as caused by the high tension which normally existsin the belt of conventional horiziontal conveyors. The horizontal conveyor of the present invention can also be positioned with the upper belt disposed within a plane which is slightly inclined with respect to the horizontal, if desired, so as to permit a slight change in elevation of the objects being transported.
Considering again the inclined conveyor 11 illustrated in Figures 1-4, the embodiment as described above involves a mode of operation wherein the end rollers 22 and 23 are simultaneously driven at equal peripheral speeds. However, it has been discovered that the operation of the inclined conveyor 11 can be still further improved by driving the lower end roller 22 at a peripheral speed which is slightly greater than the peripheral speed of the upper end roller 23. For example, by driving the lower end roller 22 at a slightly higher speed, there is created a small amount of ;
slack in the upper belt reach 24 so that the desired curvature ; of the upper belt reach is continuously maintained. When the lower end roller 22 is driven at a slightly greater speed than the upper roller 23, then the drive between the rollers 22 and 23 and the belt 13 is preferably a friction drive since this permits a limited amount of slippage to occur between the belt and one of the end rollers, thereby tending ;
to compensate for the differential in the driving speeds between the end rollers.
In this variation of the invention, the lower end -30 roller 22 is preferably driven at a speed such that its -.

peripheral velocity is in the order of 5 to 10 percent greater than the peripheral velocity of the upper end roller 23. This difference in driving speed can be achieved by causing a slight variation in the two drive trains which interconnect the motor 36 to the end rollers 22 and 23. For example, the driving sprockets 38 and 39 may be identical, but the driven sprocket 42 is preferably provided with a slightly larger diameter or number of teeth than the driven sprocket 44 associated with the upper end 10 roller. For example, the driven sprocket 42 can be pro-vided with 13 teeth, whereas the driven sprocket 44 can be provided with 12 teeth. This thus results in the lower end roller 22 being rotated at a slightly greater rate than the upper end roller 23. Alternately, the driven sprockets 42 and 44 can be identical, in which case the driving sprockets 38 and 39 are slightly different so as to achieve the desired speed differential between the upper and lower end rollers. It will be appreciated that numerous variations could be made either in the diameter of the rollers 20 themselves or in the driving and driven sprockets so as to achieve the desired speed differential between the upper and lower rollers.
Although a particular preferred embodiment of the invention has been disclosed above for illustrative purposes, it will be understood that variations or modifications thereof which lie within the scope of the appended claims are fully contemplated.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

In a belt conveyor having a housing, first and second elon-gated rollers supported on said housing for rotation about sub-stantially parallel horizontal axes, an endless flat belt sup-ported on and extending between said rollers, said belt being of substantial width and having an outer surface adapted to support articles thereon as they are being moved by said conveyor, and a drive device interconnected to one of said rollers for moving said belt, comprising the improvement wherein:
said second roller is displaced horizontally from and verti-cally above said first roller;
said belt having a non-straight upper reach which extends between said first and second rollers, said upper reach including first and second elongated belt portions which extend at a sub-stantial angle with respect to one another, said first belt portion being positioned adjacent said first roller and extending outwardly therefrom in a direction which is generally toward said second roller, said second belt portion being positioned adjacent said second roller and extending outwardly therefrom in a direc-tion which is generally toward said first roller, said second belt portion being substantially straight and inclined at a sub-tantial angle with respect to the horizontal, and a curved belt portion interconnected between said first and second belt portions;
guide means mounted on said housing and disposed for guid-ably supporting the upper reach of said belt as it extends between said first and second rollers, said guide means engaging the undersurface of said upper reach so that as it extends between said first and second rollers it is supported solely by the Claims Page 1 guidable engagement of the undersurface thereof with said guide means;
said drive device causing simultaneous rotation of said first and second rollers in the same rotational direction for causing movement of the upper reach of said belt in a direction from said first roller toward said second roller so that articles supported on said upper reach are moved upwardly by said second belt portion; and said drive device including a common drive motor, a power train drivingly connected between said motor and said second roller for causing rotation thereof at a selected peripheral velocity, and said power train being drivingly connected between said motor and said first roller for causing rotation thereof at a peripheral velocity which is at least equal to said selected peripheral velocity, whereby the upper belt reach is substan-tially free of tension and is maintained in a desired non-straight configuration due to said upper reach being supported solely by said first and second rollers and said guide means so that said upper belt reach does not require the use of any guiding structure disposed in engagement with the upper surface thereof.

A conveyor according to Claim 1, wherein said power train causes said first roller to be rotatably driven at a peripheral velocity which is slightly greater than said selected peripheral velocity of said second roller.

A conveyor according to Claim 2, wherein the peripheral velocity of said first roller is a maximum of about 10 percent greater than said selected peripheral velocity of said second roller.

Claims Page 2 A conveyor according to any one of Claims 1-3, wherein said guide means includes an elongated guide which is substantially planar and is fixed with respect to said housing, said guide extending outwardly and downwardly away from said second roller so as to be inclined with respect to the horizontal, said second belt portion being slidably supported on said guide.

A conveyor according to any one of Claims 1-3, wherein said housing includes opposed sidewalls which are positioned closely adjacent the opposite side edges of said upper belt reach, said sidewalls being disposed adjacent and projecting up-wardly above said first and curved belt portions for effectively losing the sides thereof.

A conveyor according to any one of Claims 1-3, wherein said guide means includes a first elongated guide rail fixedly asso-iated with said housing and projecting substantially horizontally way from said first roller so that at least a part of said first belt portion is slidably supported on said first guide and extends substantially horizontally, said first guide having a surface which slidably engages the underside of said first belt portion, and said guide means including a second elongated guide which is substantially planar and is fixed with respect to said housing, said second guide extending outwardly and downwardly away from said second roller so as to be inclined with respect the horizontal, said second guide having a guide surface thereon disposed in slidable supporting engagement with the undersurface of said second belt portion.

Claims Page 3 A conveyor according to Claim 1, further including align-ment means coacting between said belt and said rollers for preventing sideward displacement of said belt with respect to said rollers, said alignment means including annular groove means on said rollers and projection means fixed to said belt and projecting downwardly from the under side thereof, said projection means extending into the annular groove means on said rollers.

A conveyor according to Claim 1, wherein said power train comprises positive drive-type endless driving member means extending between and drivingly connected to said motor and both of said first and second rollers.

Claims Page 4 End of Claims