U.S. patent application number 12/622568 was filed with the patent office on 2010-03-18 for apparatus for sensing conditions local to a conveyor belt.
This patent application is currently assigned to LAITRAM, L.L.C.. Invention is credited to Jason M. Lagneaux.
Application Number | 20100065405 12/622568 |
Document ID | / |
Family ID | 40404760 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100065405 |
Kind Code |
A1 |
Lagneaux; Jason M. |
March 18, 2010 |
APPARATUS FOR SENSING CONDITIONS LOCAL TO A CONVEYOR BELT
Abstract
Apparatus and method for sensing conditions local to a modular
conveyor belt and wirelessly transmitting signals representing
those conditions to an off-belt belt monitoring system. A load cell
pin installed in a clevis formed at a hinge joint between adjacent
rows of a modular conveyor belt serves as a clevis pin to
interconnect the rows and as a sensor sensitive to belt tension
transmitted through the clevis. A special load-sensing belt module
forms the clevis and holds electronic circuitry that takes the
measurements made by the sensor, logs them in a memory element, and
transmits them wirelessly to the belt monitoring system. The
measurements may also be used as part of a closed-loop control
system to control the speed or other operating characteristics of
the conveyor system. Furthermore, a variety of sensors housed in
sensor modules similar to standard conveyor belt modules may be
installed in the belt as drop-in replacements for standard
modules.
Inventors: |
Lagneaux; Jason M.; (River
Ridge, LA) |
Correspondence
Address: |
LAITRAM, L.L.C.;LEGAL DEPARTMENT
220 LAITRAM LANE
HARAHAN
LA
70123
US
|
Assignee: |
LAITRAM, L.L.C.
Harahan
LA
|
Family ID: |
40404760 |
Appl. No.: |
12/622568 |
Filed: |
November 20, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12026824 |
Feb 6, 2008 |
7635060 |
|
|
12622568 |
|
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Current U.S.
Class: |
198/853 |
Current CPC
Class: |
B65G 17/086 20130101;
B65G 43/02 20130101; B65G 2203/042 20130101; B65G 2207/30 20130101;
G01L 5/101 20130101 |
Class at
Publication: |
198/853 |
International
Class: |
B65G 17/38 20060101
B65G017/38 |
Claims
1. A modular conveyor belt comprising: a series of rows of one or
more belt modules hingedly linked together at hinge joints between
adjacent rows; wherein at least one of the belt modules is a
load-sensing belt module that includes a load sensor making
measurements of belt tension in at least a portion of the
load-sensing belt module; wherein the load-sensing belt module
further includes a memory element for storing as a group a series
of the measurements of belt tension made by the load sensor.
2. A modular conveyor belt as in claim 1 wherein the load-sensing
belt module further includes a transmitter to wirelessly transmit
signals representative of the measurements of belt tension made by
the load sensor.
3. A modular conveyor belt as in claim 1 wherein the load-sensing
belt module further includes one or more electrical cells to power
the load sensor.
4. A modular conveyor belt as in claim 2 wherein the load-sensing
belt module further includes: a cavity housing the memory element
and the transmitter; and a cover over the cavity to retain the
memory element and the transmitter.
5. A modular conveyor belt as in claim 1 wherein the load-sensing
belt module is positioned at an outside edge of the modular
conveyor belt.
6. A modular conveyor belt as in claim 1 wherein the load-sensing
module includes a plurality of laterally spaced apart hinge
elements along one end and fewer laterally spaced hinge elements
along the other end.
7. A modular plastic conveyor belt comprising: a series of rows of
one or more standard belt modules hingedly linked together between
adjacent rows; at least one sensor module including: a sensor
making measurements of a local condition; a memory element for
storing the measurements as a group; and a transmitter for
wirelessly transmitting signals representing the group of
measurements.
8. A modular plastic conveyor belt as in claim 7 wherein the at
least one sensor module has a cavity in which the memory element
and the transmitter are embedded.
9. A modular plastic conveyor belt as in claim 7 wherein the sensor
is a load cell measuring tension in the modular conveyor belt.
10. A modular plastic conveyor belt as in claim 7 wherein the local
condition that the sensor measures is selected from the group
consisting of temperature, humidity, and belt tension.
11. A conveyor system comprising: a conveyor belt including: a
sensor making measurements of a local conveyor system condition; a
memory element for storing the measurements as a group; and a
transmitter for wirelessly transmitting signals representing the
group of measurements; a controller using the group of measurements
to control the operation of the conveyor system in a closed-loop
system.
12. A conveyor as in claim 11 wherein the local condition that the
sensor measures is selected from the group consisting of
temperature, humidity, and belt tension.
13. A conveyor as in claim 11 wherein the sensor is a temperature
sensor making temperature measurements and wherein the controller
provides a signal to control the temperature.
14. A conveyor as in claim 11 wherein the sensor is a load sensor
making measurements of belt tension and wherein the controller
provides a motor-control signal to control the speed of the
conveyor belt.
15. A conveyor as in claim 11 wherein the conveyor belt is a
modular plastic conveyor belt comprising a series of rows of one or
more standard belt modules hingedly linked together between
adjacent rows and a sensor module disposed in one of the rows and
housing the sensor, the memory element, and the transmitter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 12/026,824, entitled "Apparatus and Method for
Sensing Conditions Local to a Modular Conveyor Belt," filed Feb. 6,
2008.
BACKGROUND
[0002] The invention relates generally to power-driven conveyors
and, more particularly, to methods and devices for making
measurements of conditions local to modular conveyor belts from
within the belts and wirelessly transmitting those measurements for
monitoring or controlling the operation of the belt or the process
in which it is used.
[0003] U.S. Pat. No. 4,587,852, "Conveyor Belt Tension Sensing,"
describes a radio transmitter and a tensile force sensor that
includes strain gauges mounted in the limbs of a support link that
is adapted for connection to joint components at the ends of
straight-running flat belt portions. The strain gauges sense belt
tension and derive a corresponding signal that is transmitted by
the transmitter to a receiver and monitor. The belt has to be
unlaced and relaced every time the support link is installed or
removed. And because the belt is longer with the support link
installed, the tension has to be adjusted.
[0004] It is often desirable to detect the tension at the outside
of a modular plastic conveyor belt in a spiral conveyor. Knowing
the tension in a side-flexing spiral or radius belt at the outside
of a turn is useful in detecting imminent failures or in adjusting
the tension for optimal operation. This is conventionally done in
spiral belt conveyor systems by a data-logging tension-sensing
device temporarily attached along outer belt modules as the belt
follows its helical path along the spiral conveyor's drive tower.
But the sensing device has to be removed before it reaches the
belt's return path and falls off. When the device is removed, the
belt tension data it collected is dumped to a computer for
analysis.
[0005] Thus, there is a need for a device that can sense
conditions, such as belt tension at the outside of a turn, in a
conveyor belt without being destroyed and without having to be
removed from the belt.
SUMMARY
[0006] This need and other needs are satisfied by a modular
conveyor belt embodying features of the invention, including a
load-sensing belt module. The modular conveyor belt is constructed
of a series of rows of one or more belt modules hingedly linked
together at hinge joints between adjacent rows. The load-sensing
belt module includes a load sensor that makes measurements of belt
tension in at least a portion of the load-sensing belt module,
which further includes a memory element for storing as a group a
series of the measurements of belt tension made by the load
sensor
[0007] Another modular plastic conveyor belt comprises a series of
rows of one or more standard belt modules hingedly linked together
between adjacent rows and at least one sensor module. The sensor
module includes a sensor making measurements of a local condition,
a memory element for storing the measurements as a group, and a
transmitter for wirelessly transmitting signals representing the
group of measurements.
[0008] In another aspect of the invention, a conveyor system
comprises a conveyor belt that includes a sensor making
measurements of a local condition, a memory element for storing the
measurements as a group, and a transmitter for wirelessly
transmitting signals representing the group of measurements. A
controller uses the group of measurements to control the operation
of the conveyor system in a closed-loop system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These features and aspects of the invention, as well as its
advantages, are better understood by referring to the following
description, appended claims, and accompanying drawings, in
which:
[0010] FIG. 1 is a top plan view of a portion of a modular conveyor
belt embodying features of the invention including a load-sensing
edge module;
[0011] FIG. 2 is an enlarged view of a portion of the modular
conveyor belt of FIG. 1 showing the edge module;
[0012] FIG. 3 is an exploded isometric view of the edge module of
FIG. 1 viewed from the top side of the module;
[0013] FIG. 4 is an exploded isometric view of the edge module of
FIG. 1 viewed from the bottom side of the module;
[0014] FIG. 5 is an isometric view of a two-axis bearing used in
the edge module of FIG. 3;
[0015] FIG. 6 is a block diagram of the electronic circuits used in
the edge module of FIG. 1; and
[0016] FIG. 7 is an isometric view of a portion of a modular
conveyor belt embodying features of the invention including
replaceable sensor modules.
DETAILED DESCRIPTION
[0017] A portion of a modular conveyor belt following a curved path
is shown in FIGS. 1 and 2. The conveyor belt 10 depicted in this
example is a SPIRALOX.TM. 1.1 Radius modular plastic conveyor belt
manufactured and sold by Intralox, L.L.C. of Harahan, La., U.S.A.
The belt is constructed of a series of rows 12 of one or more belt
modules 14. Hinge elements 16 having aligned openings 18 are
laterally spaced apart along leading and trailing ends of each row.
Hinge rods 20 received in lateral passageways formed by the aligned
openings through interleaved hinge elements of adjacent belt rows
connect the rows together at hinge joints 21 and allow the belt to
articulate about drive and idle sprockets and return rollers.
[0018] The conveyor belt shown in this example is a radius, or
side-flexing, belt capable of negotiating turns or wrapping
helically around a spiral-conveyor drum or capstan. As shown in
FIG. 1, the inside edge 22 of the belt collapses on itself in
riding along the curved outer surface 24 of a drive capstan in a
spiral conveyor. Meanwhile, the outside edge 23 of the belt is
allowed to fan out because it is following a longer path around the
capstan. The openings 18 in one or both of the leading and trailing
hinge elements are elongated in the direction of belt travel 26 to
allow the inside edge to collapse in a turn.
[0019] An important factor in determining the life of the spiral
belt and its performance is the tension in the belt. In a spiral
conveyor, in which a major portion of the belt's path is its
helical path up or down the capstan, the majority of the belt
tension is borne by the hinge elements at the outside of the turn.
The collapsed inside edge and the interior portions of the belt
carry almost no tension in a turn. A load-sensing belt module 28 is
positioned at the outside edge of the belt row in place of a
standard belt module or belt module edge portion. The load-sensing
module extends inward from the outside edge of the belt far enough
to capture all or at least a known percentage of the tension in the
belt as it makes a turn. A complementary belt module 30 in an
adjacent row cooperates with the load-sensing module to concentrate
the belt tension at a measuring position 32 without changing the
pull characteristics of the belt. Both the load-sensing module and
the complementary module have hinge elements 34, 35 along one end
designed to interleave with the hinge elements 16 of standard belt
rows and receive a hinge rod. The hinge rod extending through the
hinge elements on the load-sensing module is prevented from
escaping at the outside of the module by a plug 33 that occludes
the rod passageway through the interleaved hinge elements. A
bias-cut edge 36 on the inner side of a complementary module
provides room for the collapse of the belt inward of the outer
edge.
[0020] Further details of the load-sensing module 28 and its
complementary module 30 are shown in FIGS. 3 and 4. The
load-sensing module has hinge elements 34 that are laterally spaced
along one end to be compatible with the hinge elements of the
standard belt modules. A hole 37 in the outside edge of the module
intercepts the passageway through the hinge elements and receives
the rod retention plug 33. The other end of the load-sensing module
has only two enlarged hinge elements 38, 39 that form a shackle, or
clevis 40. A two-axis bearing in the form of a puck 42 resides in
the opening in the clevis. A bore 43 is formed through the outer
circular wall of the puck as shown in FIG. 5. The bore is aligned
coaxial with a passageway 44 through the clevis end of the
load-sensing module. A load sensor, such as a load cell 46, is
inserted into the passageway from the side edge of the module. The
load cell has a pin portion 48 extending from a head 49 at a
shoulder 51. The pin portion is centered in the bore of the puck,
which can rotate about the pin. A central portion 50 of the pin
resides in the puck; proximal and distal portions 52, 53 of the pin
reside in the two hinge elements 38, 39 of the load-sensing module
flanking the puck. Further details of an exemplary load cell are
given in U.S. Pat. No. 3,695,096 to Kutsay, "Strain Detecting Load
Cell," which is incorporated by reference.
[0021] The puck is received in a projection 54 extending outward
from one end of the complementary belt module 30. The projection 54
has a recess 56 shaped to snugly, but rotationally hold half the
puck. One end of a T-shaped retainer 58 sits in a mating receptacle
60 in the complementary belt module and holds the other half of the
puck. The retainer may be fastened to the projection in a
conventional manner, such as by screws, adhesives, or thermal
bonding, such as by ultrasonic welding. Together, the projection
and the retainer form an oversized hinge element coupled to the
load-sensing module through the puck and the pin portion of the
load cell. The circular outer wall of the puck allows the
complementary module to rotate about a second axis 62 radial to the
axis of the pin and perpendicular to the plane of the load-sensing
module to properly load the load cell as the belt fans out at the
outside of a turn.
[0022] When the load-sensing module is connected to the
complementary module as described, the pin portion 48 of the load
cell acts as a clevis pin. When the belt is in tension, the central
portion 48 of the pin is pulled in one direction by the action of
the complementary module's oversized hinge element on the puck, and
the proximal and distal portions 52, 53 are pulled in the opposite
direction by the action of the two hinge elements 38, 39 of the
load-sensing module on the pin. This causes a shear stress in the
pin in thinned regions 64, 65 between the central portion and the
proximal and distal portions. Orthogally disposed pairs of strain
gauges within the hollow pin portion of the load cell at the
thinned regions are sensitive to the shear stress, which is
proportional to the belt tension. To increase the sensitivity of
the response of the load cell to belt tension, the load cell has a
flat 66 formed on its head 49 that cooperates with a flat front
edge 70 on a cover 98. The front edge of the cover juts into the
passageway 44 from a cavity 95 that opens into the passageway to
orient the pin circumferentially with the strain gauges in the
direction of maximum sensitivity.
[0023] In a preferred version, the four strain gauges 71--two at
each thinned region 64, 65 of the pin--are arranged electrically in
individual legs of a conventional bridge circuit 72, as shown in
FIG. 6. The bridge is energized by a regulated voltage 74 at one
corner of the bridge. A voltage regulator 76 maintains a constant
voltage to the bridge. A power source, for example, a battery 78,
such as provided by a pair of 1.5-volt dry cells or a pair of
3.6-volt lithium ion cells, powers the voltage regulator and the
other electronic components in the load-sensing module. The output
of the bridge circuit is conditioned in a differential amplifier 80
and sent to an analog-to-digital converter 82, which periodically
samples and digitizes the strain gauge signals and provides digital
measurements to a controller 84, such as a microprocessor or
microcontroller. The controller may log the digital measurements to
a memory element 86 as is or after applying further algorithmic
processing, such as filtering or scaling, to the measurements. The
logged measurements may then be converted to radio signals in a
transmitter 88, which may also include a receiver 93, and
transmitted wirelessly from the belt over an antenna 90 to an
off-belt belt monitoring and control system 91 that would include a
transmitter and a receiver. The memory allows a number of
measurements to be stored and uploaded wirelessly as a group in a
single transmission when the antenna is close to the belt
monitoring system. This can result in extended battery life by
minimizing the transmission duty cycle and the distance over which
the transmitter must transmit. But it would also be possible to
transmit signals representing the measurements more frequently,
such as transmitting one measurement each sample time. In such a
case, a series of measurements would not have to be logged in a
memory element, but single measurements could be stored before
being transmitted. The circuitry may also use the receiver to
receive command and control signals from the belt monitoring
system.
[0024] The measurements may also be used to adjust the operation of
the conveyor or the associated process in a closed-loop control
system. An error signal 104 proportional to the difference between
a signal or signal level 106 representing, for example, the tension
in the belt and a tension set point 108, set through an operator
interface in the monitoring and control system 91, is used as the
input to a motor controller 110 that produces a motor-control
signal 111 controlling the speed of a motor 112 driving the belt.
The motor controller, as shown in the example of FIG. 6, or the
belt monitoring and control system 91 may include the control logic
to implement the control algorithm, which may define a
proportional-integral-differential (PID) loop or other conventional
control loop. The motor for a spiral conveyor system can be used to
adjust the speed of the drive drum 114 and, consequently, the
amount of overdrive used in driving the spiral belt 10 in its
helical path around the drum. In the same way, an alternative
sensor or an auxiliary sensor 99, such as a temperature sensor in
the conveyor belt, could make temperature measurements, which could
be transmitted from the belt to the monitoring and control system
91 to raise or lower the process temperature via another control
signal 113. Thus, a sensor embedded in the belt can be used to
measure local conveyor system conditions, such as ambient
temperature, or belt conditions, such as tension, and control those
conditions.
[0025] The electronic circuits, except the bridge, which resides in
the load cell, reside on a circuit board 92 as shown in FIGS. 3 and
4. The battery resides in the cavity 95 adjacent to the load cell.
The circuit board housing the electronics resides in another cavity
94 on the opposite side of the load-sensing belt module. Wires 96
passing through a mouse hole 97 in the front edge 70 of the cover
98 connect the bridge in the load cell to the electronics and the
power source. The cover covers the cavities and retains the
batteries and electronic components in the belt module. A slit 102
in the front edge of the cover receives a peripheral portion 103 of
the head of the load cell between the flat 66 and the shoulder 51
to register the load cell axially in the passageway. The cover is
conventionally fastened to the belt module, such as by a snap-fit
provided by tabs 100 on the side edges of the cover received in
mating receptacles 101 formed in the outside edges of the module,
and forms its bottom surface. Like the other belt modules, the
load-sensing belt module may be made of a plastic material, but it
could alternatively be made of metal. The cover, however, is
preferably made of a non-metal, such as plastic, that has little
effect on the transmitter's range and wears against the conveyor
belt's support rails with less friction than a metal. As another
variation, the cavities could open onto the top of the module with
the cover forming a portion of the top surface. As an alternative
to the cover, potting compound could be used to retain and protect
the electronic components and the batteries in the cavities.
[0026] In another version of a modular conveyor belt 115, shown in
FIG. 7 as a straight-running belt, a sensor module 116 is used in
place of a standard belt module 118. The sensor module has a
physical structure similar to that of the standard belt module. In
this example, the width and pitch of the two modules are the same,
as is the configuration of hinge elements 120, e.g., spacing, size,
lateral position, and number of hinge elements, along leading and
trailing ends. A standard module or a sensor module is removed from
the belt by retracting hinge rods 122 from the lateral hinge-eye
passageways 124 through the interleaved hinge elements at each end
of the belt row to free the module. An inventory 126 of sensor
modules 116A-C containing various kinds of sensors within the body
of the module or attached appurtenances may be maintained and
selectively installed as drop-in replacements in place of the
removed standard module or sensor module by reinserting the hinge
rods in the passageways to retain the replacement module in
position in the belt row. Thus, sensor modules housing a variety of
sensors to measure various local conditions (e.g., belt tension,
temperature, humidity) are designed to be easily replaceable,
integral parts of the belt without significantly changing its
length or its operating characteristics.
[0027] Although the invention has been described in detail with
respect to a preferred version, other versions are possible. For
example, the sensor-outfitted module, which has been described as a
belt-edge module in the spiral-conveyor application and in the
straight-running belt example, may be located in an interior
position of the belt for other applications, such as measuring
tension in a straight-running belt or with a sensor for sensing
temperature. So, as these few examples suggest, the scope of the
claims is not meant to be limited to the preferred versions
described in detail.
* * * * *