Note: Descriptions are shown in the official language in which they were submitted.
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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
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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
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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
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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
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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
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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,
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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
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~)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
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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
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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
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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,
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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 -
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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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