U.S. patent application number 16/733332 was filed with the patent office on 2020-05-07 for method and system for wear monitoring using rf reflections.
This patent application is currently assigned to REI, Inc.. The applicant listed for this patent is REI, Inc.. Invention is credited to Daniel J. Brunner, Randall Lee JOHNSON, Robert KOONTZ, Randy RICHARDSON, Alex SCHUMACHER, Jeffrey J. SCHWOEBEL.
Application Number | 20200141881 16/733332 |
Document ID | / |
Family ID | 61905994 |
Filed Date | 2020-05-07 |
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United States Patent
Application |
20200141881 |
Kind Code |
A1 |
Brunner; Daniel J. ; et
al. |
May 7, 2020 |
METHOD AND SYSTEM FOR WEAR MONITORING USING RF REFLECTIONS
Abstract
In an embodiment, a system for wear monitoring, includes a wear
surface, a metallic reflector embedded in the wear surface, a
radio-wave transmitter, and a radio-wave receiver. The metallic
reflector reflects radio waves transmitted by the radio-wave
transmitter for detection by the radio wave receiver. Attenuation
of the radio waves between transmission by the radio-wave
transmitter and detection by the radio-wave receiver indicates a
degree of wear of the wear surface.
Inventors: |
Brunner; Daniel J.; (Salt
Lake City, UT) ; RICHARDSON; Randy; (South Jordan,
UT) ; KOONTZ; Robert; (Herriman, UT) ;
SCHUMACHER; Alex; (Salt Lake City, UT) ; SCHWOEBEL;
Jeffrey J.; (Park City, UT) ; JOHNSON; Randall
Lee; (Salt Lake City, UT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
REI, Inc. |
Salt Lake City |
UT |
US |
|
|
Assignee: |
REI, Inc.
Salt Lake City
UT
|
Family ID: |
61905994 |
Appl. No.: |
16/733332 |
Filed: |
January 3, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15730465 |
Oct 11, 2017 |
10557804 |
|
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16733332 |
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62477228 |
Mar 27, 2017 |
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62430400 |
Dec 6, 2016 |
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62417763 |
Nov 4, 2016 |
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62407095 |
Oct 12, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60C 25/0551 20130101;
F16H 2057/014 20130101; G01N 22/02 20130101; B66B 7/1215 20130101;
B60C 11/246 20130101; B60C 11/243 20130101; B65G 43/00 20130101;
B60C 25/007 20130101; B60C 23/06 20130101; F16H 57/01 20130101 |
International
Class: |
G01N 22/02 20060101
G01N022/02; B65G 43/00 20060101 B65G043/00; B60C 25/05 20060101
B60C025/05; B60C 25/00 20060101 B60C025/00; B60C 23/06 20060101
B60C023/06; B60C 11/24 20060101 B60C011/24 |
Claims
1-13. (canceled)
14. A system for wear monitoring, comprising: A non-metallic wear
surface; a redundant transceiver wear sensor in the wear surface; a
recessed reflector antenna; wherein the change in resistance of the
redundant transceiver wear sensor indicates the degree of wear of
the non-metallic wear surface, and the connected recessed reflector
antenna transmits the resistance information as an assessment of
wear as a function of time.
15. The system for wear monitoring of claim 14, wherein the wear
surface is a tire.
16. The system for wear monitoring of claim 14, wherein the wear
surface is a non-metallic liner.
17. The system of claim 14, wherein the recessed reflector antenna
is a parabolic reflector.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/730,465, filed on Oct. 11, 2017. U.S.
patent application Ser. No. 15/730,465 claims priority to U.S.
Provisional Patent Application No. 62/407,095, filed on Oct. 12,
2016, U.S. Provisional Patent Application No. 62/417,763, filed on
Nov. 4, 2016, U.S. Provisional Patent Application No. 62/430,400,
filed on Dec. 6, 2016, and U.S. Provisional Patent Application No.
62/477,228, filed on Mar. 27, 2017. U.S. patent application Ser.
No. 15/730,465, U.S. Provisional Patent Application No. 62/407,095,
U.S. Provisional Patent Application No. 62/417,763, U.S.
Provisional Patent Application No. 62/430,400, U.S. Provisional
Patent Application No. 62/477,228 are each incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure relates generally to surface wear
monitoring and, more particularly, but not by way of limitation, to
sensors and antennas embedded in equipment having wear surfaces for
wear monitoring. In one embodiment, the disclosure further relates
to methods and systems for providing wear, tear, or rupture status
of equipment and items having wear surfaces such as, for example,
conveyor belts and tires. In a further embodiment, the disclosure
relates to the use of RF reflectors embedded in a belt or tread of
a tire and positioned in such a way as to be impacted by wear while
reflecting RF radio waves from an RF radio wave transmitter to a
radio wave receiver.
BACKGROUND
[0003] Every tire and belt has a means to adapt to host equipment
and a life-cycle that starts when the belt or tire is installed and
ends when wear-out limits are reached. If the belts or tires are
worn beyond the wear-out limits or damaged, the host may be damaged
or become unsafe. As belts or tires are used, it is normal for
overall belt or tire performance to change. In addition, irregular
belt or tire-tread wear may occur for a variety of reasons that may
lead to replacing a belt or tire sooner rather than later. Regular
monitoring of wear condition of belts and tires not only provides
an indication of when it is time to replace the belt or tires, it
can also help detect other needed maintenance and get the most
value out of the equipment. Presently, monitoring of belt and tire
wear is performed manually. What is needed is a method and system
that provides automated status updates relative to wear, tear, or
rupture status of equipment and items having wear surfaces such as,
for example, belts and tires.
SUMMARY
[0004] Exemplary embodiments disclose a method and system for
providing automated status updates relative to wear, tear, or
rupture status of equipment having wear surfaces such as, for
example, belts and tires. In one embodiment specifically set forth
herein, a metallic reflector embedded in the belt or tread of a
tire and positioned in such a way as to reflect RF radio waves from
an RF radio wave transmitter and focus the reflections to a radio
wave receiver.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] For a more complete understanding of the present disclosure
and for further objects and advantages thereof, reference may now
be had to the following description taken in conjunction with the
accompanying drawings in which:
[0006] FIG. 1 illustrates reflections of RF energy from various
types of surfaces;
[0007] FIG. 2 illustrates a sinusoidal pattern of electrical
potential of an RF signal;
[0008] FIG. 3A-3B illustrate a wear monitoring system having
reflectors embedded into the device being monitored in accordance
with an exemplary embodiment;
[0009] FIG. 4 illustrates a conveyor system having steel cables
embedded therein in accordance with an exemplary embodiment;
[0010] FIG. 5 is a cross-sectional view of a steel cord conveyor
belt system in accordance with an exemplary embodiment;
[0011] FIG. 6 is a cross-sectional view of a torn conveyor belt
system in accordance with an exemplary embodiment;
[0012] FIG. 7 illustrates front and side views of a serpentine belt
monitoring system in accordance with an exemplary embodiment;
[0013] FIG. 8 illustrates front and side views of a v-belt
monitoring system in accordance with an exemplary embodiment;
[0014] FIG. 9 illustrates a wear monitoring system having
stationary sensors and reflectors in accordance with an exemplary
embodiment;
[0015] FIG. 10 illustrates an alternative embodiment for the
physical implementation of a reflector tire wear sensor system;
[0016] FIG. 11 illustrates an alternative embodiment for the
physical implementation of a reflector slurry pipe liner wear
sensor system;
[0017] FIG. 12 illustrates a transmission system using remote dual
antennas with recessed reflectors;
[0018] FIG. 13 illustrates the wear path of a tire;
[0019] FIG. 14 illustrates a wear path monitoring circuit in
accordance with an exemplary embodiment;
[0020] FIG. 15A-15C illustrate physical implementation of the
sensors within the tire in accordance with the embodiment of FIG.
14;
[0021] FIG. 16 illustrates an alternative embodiment of a wear path
monitoring circuit; and
[0022] FIG. 17A-17C illustrate physical implementation of the
sensors within the tire in accordance with the embodiment of FIG.
16.
RADIO FREQUENCY REFLECTION FOR NON-FERROUS MATERIAL WEAR
SENSING
[0023] The following background is presented for a better
understanding of the principles of the present disclosure. At lower
power frequencies, the effects of ground (such as the surface of
the Earth) interact with RF signals to bend their course of travel.
This bending effect allows lower-frequency RF signals, such as
those used in radio and television, to follow the contours of the
Earth such as, for example, bending along hills and valleys. As the
frequency of the RF signals increase, such as, for example, in the
case of microwave signals, this ground effect is less predominant
and the signals follow straight courses, regardless of the presence
of ground objects. Because these signals follow straight lines,
they may be blocked by objects such as buildings, hills, or other
structures. At these higher frequencies, these signals are referred
to as line-of-sight signals.
[0024] When RF signals contact metallic surfaces, part of the
signal energy is absorbed into the structure and part is reflected.
RF energy that is absorbed is lost in the surface in the form of
heat. Incident waves are redirected relative to the angle they
strike the surface. Metallic surfaces can generally be classified
as being: flat, convex or concave curved or rounded or flattened
irregular. FIG. 1 depicts the reflections of the RF energy for the
various types of surfaces: (A) flat, (B) convex curved and (C)
concave curved, (D) irregular curved and (E) irregular flat
surfaces.
[0025] As RF signals travel, the electrical potential of the signal
varies in a sinusoidal pattern as depicted in FIG. 2. The signal
voltage (V) 201 oscillates about a voltage reference point
V.sub.REF 202 (may be zero volts). The number of times the signal
crosses this reference level in the same direction (either positive
or negative-going, but not both) each second defines the frequency
(f) in hertz (Hz). Voltage levels are the positive peak voltage
(V.sub.P) 203, the negative peak voltage (-V.sub.P) 204 and the
peak-to-peak voltage (V.sub.P-P) 205. Since, in a vacuum, RF
signals propagate at the speed of light (c), the wavelength
(.lamda.) 206 is defined as the speed of light divided by the
signal frequency (.lamda.=c/f). The term signal amplitude generally
refers to the level (positive and/or negative) that the signal
deviates from V.sub.REF.
[0026] Addressing now Applicant's approach to utilizing RF
reflections for wear monitoring, specific technical aspects are
herein presented. Due to physical, cost and regulatory constraints,
there is a range of RF frequencies that are effective for
monitoring wear. Low frequencies have large wavelengths. These
force reflectors to be very large for reasonable signal strength.
This adds to cost and may make implementation physically
impossible. High frequency RF signals are costly to generate and
are not commonly used in other applications. Government regulations
may also impact the frequencies that are chosen. Currently low cost
RF components are not readily available above 20 GHz (.lamda.=15
mm). RF wavelengths below 1 GHz (.lamda.>300 mm) are physically
harder to implement. Government regulations such as FCC (United
States), CE (Europe), etc. limit the frequencies and amplitudes
that may be used without a license. Applicants have observed that
signals in the 1 GHz to 20 GHz range exhibit line-of-sight
characteristics and could be useful for wear monitoring because
reflections will be linear. Signals greater than 20 GHz could also
be useful when the technology is readily available. As less
expensive and higher frequency components are developed, it is
desirable to use these due to their smaller wave lengths.
[0027] The use of RF signals to monitor the wear in various
components such as tires, conveyor belts, slurry pipe liners and
haul truck bed liners etc. rely on the general behaviors of RF
signals described above. Specific implementations of these concepts
will be described in detail below. The general concept that makes
use of RF signals for monitoring is described here. When referring
to the types of reflections listed above, Applicants will generally
relay on flat, concave and irregular surfaces. These break down
into general application types as follows: [0028] Stationary
Sensors and Moving Reflectors: Conveyor and drive belts are a good
example of this. The RF transmitter and receiver are mounted at a
fixed vantage point with the belts having embedded reflectors
moving past them.
[0029] Wear monitoring is least complicated when RF reflecting
structures are not present. FIG. 3A and FIG. 3B show examples of
wear monitoring where the reflectors are embedded into the device
being monitored for wear 301. The device being monitored will be
referred to as a belt. As the embedded reflector 302 passes over
the antennas 303 and 304, the transmitted signal 305 is reflected
306 back into the receiver 304, as shown in FIG. 3A. When the
reflector 302 is past the sensors, the RF wave passes through the
belt 301 and no signal is received. When the wear reaches the
sensor it will begin to be worn away and the pulse width 307 and
amplitude 308 of the received signal will diminish. As shown in
FIG. 3B, the receiver 304 may alternatively be positioned on the
opposite side of the belt 301. In this embodiment, the presence of
the reflector 302 is detected by a drop in the signal of amplitude
309. Placing embedded reflectors at different levels allows
multiple wear depths to be monitored. Placing reflectors in
patterns will allow position of the belt to be determined. [0030]
Applications with embedded structural components that reflect RF.
Good examples of this are conveyor belts with embedded steel cables
and/or steel mesh to add structural strength:
[0031] The addition of reflective structural components adds
complexity to the monitoring, but it also adds more information to
the signal. First, consider the case where steel cables are
embedded at regular intervals to strengthen a conveyor belt. FIG. 4
shows this example. Because the cables 401 are made up of multiple
strands of steel wires and the general shape of the cable is convex
with respect to RF signal reflections, most of the signals will not
be reflected to the receiver as the cable 401 passes over the
transmitter 402 and receiver 403 pair. The reflections from the
cables will form small signal levels at the receiver. Depending on
whether the antenna orientation corresponds to that of FIG. 3A or
that of FIG. 3B, the strength of signal received by the receiver
will either increase 404 (FIG. 3A orientation) or decrease 405
(FIG. 3B orientation) as the reflectors 406 and cables 401 pass
over the antennas. These signals can be processed by the system to
determine the speed and relative position of the belt. In this
case, the longer pulses correspond to the wear depth reflectors and
the shorter pulses correspond to the cables 401.
[0032] Consistent with the above, there is now shown and described
Applicant's approach of wear monitoring for conveyor belts and the
like. In one embodiment, the present method and system may be
installed on and with conveyor belt systems, as illustrated in FIG.
5. Installation may take place during the belt manufacturing
process or in the field as an aftermarket component of the belt.
Several radio reflectors, metallic mesh or metallic belt fabric is
set at predetermined depths into the belt 501, along all or some of
its width and in an orientation perpendicular, parallel, or oblique
to belt movement 502. A transmitter 503 conveys radio waves that
reflect off of the metal strips 504. The direct or reflected
(depending again on FIG. 3A or FIG. 3B orientation) radio waves are
collected by at least one radio receiver 505 located as to receive
reflected radio waves from the transmitter. The radio receivers 505
are capable of measuring antenna gain. The characteristics of the
radio signal collected by the receiver(s) 505 are altered if wear
or damage removes any of the metal strips 504 embedded in the belt
or if the belt rapidly changes in lateral position (tracking). If
excessive wear, damage, or incorrect positioning of the belt is
detected, an alarm can be sent to an operator or the belt may
automatically be shut off. Steel cord 506 may run laterally and/or
longitudinally through standard belts at regular intervals. In
various embodiments, monitoring reflections from theses reinforcing
wires allows for calculation of belt speed. Metal strips may also
be embedded in the belt at a depth and or distance from the
centerline 507 unlikely to wear or be damaged in different patterns
508. The shape of radio signal vs. time curve collected by the
receiver 509 from the transmitter 510 is a unique identification
code to different points along the belt. These identification
reflectors are not continuous in the direction of belt movement and
may have unique dimensions within a single identification code.
This may be used to pinpoint localized damage and/or clock belt
velocity. With belt velocity, the reflections from two points can
be used to determine the distance between those two points and belt
stretch may be determined. Determining stretch across a spliced
section of belt allows monitoring the splice's integrity and can be
accomplished with this disclosure as previously described. Belt
velocity can be compared to the tangential velocity of a pulley,
which is related to its angular velocity and radius, or idler
roller to determine belt slippage and pulley or idler roller wear.
Wear of the belt is expected to be greater near the middle of the
belt so identification codes should be embedded near the edge of
the belt, and wear reflectors near the centerline 507 of the belt
501. The explicit orientation of the transmitter and receiver array
does not need to be uniquely specified given that the wear
monitoring system may function successfully as described with the
transmitter 503 or 510 and receiver 505 or 509 in many different
relative positions and orientations, such as the orientations shown
in FIG. 3A and FIG. 3B.
[0033] In the orientation of FIG. 3B, characteristics of the
received radio signal may also be altered if damage occurs to the
belt but not reflectors. This is because the rubber material of the
belt attenuates the radio signal to some degree. In FIG. 6 for
example, if a tear 601 in the belt 602 occurs along a path 603 that
is monitored by the transmitter 604 and receiver 605, some of the
transmitted radio signal will pass through the open space of the
tear 601 with little attenuation and the receiver 605 will realize
an increase in signal strength 606.
[0034] FIG. 7 illustrates an embodiment of the disclosure that is
embedded in a multi-rib serpentine belt 701. Metal reflectors 702
are solid or mesh and are embedded at predetermined depths in the
ribs of the belt 701. If a mesh is used, the mesh spacing must be
less than 1/4 of the radio transmitter wavelength in order to
effectively reflect radio waves. The reflectors are staggered in
such a way (see A-A' and B-B') that a side view of the belt would
appear to show continuous lengths of metal reflectors along the
belt. Staggering the reflectors allows the radio transmitter 703
signal received by receiver array 704 to be representative of the
condition of multiple belt ribs at any given time. Staggering the
reflectors 702 also allows the belt 701 to be more flexible than if
reflectors 702 were continuous along the entire length of the belt
701. Decreased attenuation of the radio signal is indicative of rib
damage or wear.
[0035] Some belts 801 may only be made with only one rib, as shown
in FIG. 8. With such belts, it is an option to embed a single
reflector 802 (mesh) along the length of the belt 801. It is also
possible to stagger reflectors 802 along the width and length of
the belt, as illustrated in FIG. 7. The same transmitter and
receiver configuration as previously described for FIG. 7 may be
used with single rib, v-belts. [0036] Relatively Stationary Sensors
and Reflectors: Tires are a good example of this. The RF
transmitter, receiver and reflector all move together as a single
unit within the tire as it rotates. When the sensor is required to
move with the reflector, the signals only change as wear
occurs.
[0037] FIG. 9 shows an example of a wear monitor system where the
sensors and reflectors 901 are stationary with respect to each
other. When the signal is transmitted, some of the signal bypasses
the reflector and is lost 902. The RF wave also spreads as it
moves. A parabolic reflector 901 is used to focus the reflections
on the receiver 903. Before any wear of the reflector 901
commences, the signal levels will be the greatest at the receiver
903. As wear occurs, more of the RF signal will bypass the
reflector 901. A properly designed reflector will still focus
enough RF energy on the receiver to be detected when the maximum
wear depth is reached. This signal amplitude at the receiver will
indicate the progression of wear on the reflector, and thereby
indicate the wear on the device being monitored.
[0038] Referring now to FIG. 10, there is shown an embodiment for
the physical implementation of the sensor of FIG. 9 within a tire,
slurry pipe liner, haul truck bed liner or hose. In this
embodiment, the placement of the sensor within a tire tread is
specifically described and, in similar fashion, may be used with
the belts described above. As shown in FIG. 10, a metallic
parabolic reflector 1001 is embedded in the tread 1002 of the tire
1003 and positioned in such a way as to reflect radio waves 1004
from a radio wave transmitter 1005 and focus the reflections to a
radio wave receiver 1006. The transmitter 1005 and receiver 1006
are mounted to a PCB 1007 that is attached to the inside surface
1008 of a metal support ring 1009 within the tire 1003, beneath the
tire tread 1002. Apertures 1010 are cut through the support ring
1009 to allow the transmission of radio waves 1004 between the
transmitter 1005, the reflector 1001, and the receiver 1006. A
bracket 1011 is attached to the reflector 1001 may be used to
assist in positioning of the reflector 1001 within the tire tread
1002. As the tire tread 1002 wears, the arc length 1012 of the
reflector 1001 decreases and the strength of the signal
acknowledged by the receiver 1006 diminishes. The strength of the
signal is therefore a function of the amount of tread wear. In
similar fashion, parabolic reflectors may be utilized in conveyor
and related belt systems.
[0039] Referring now to FIG. 11, a plurality of metallic reflectors
1101 are embedded in a slurry pipe liner 1102 for example at
different depths 1103. Each reflector 1101 is associated with a
transmitting antenna 1104 and a receiving antenna 1105. The
transmitting 1104 and receiving antennas 1105 are in communication
with a PCB 2006 that is mounted in a milled flat 1107 in the outer
pipe wall 1108. The PCB 1106 may be protected by a material 1109
such as PTFE that allows penetration of a radio signal. The
transmitting antenna 1104 transmits a radio signal through an
aperture 1110 in the outer pipe wall 1108 in the direction of the
reflector 1101. The aperture 1110 may be filled with a material
1111 such as PTFE that allows penetration of a radio signal. The
radio signal reflects off of the reflector 1101 and is acknowledged
by the receiving antenna 1105. The PCB 1106 stores the data from
each set of reflector 1101 and antennas 1104 and 1105. The PCB 1106
is in communication with another transmitting antenna 1112 that
transmits the information that is stored on the PCB 1106 to the
outside of the pipe wall 1108 for upload to a mobile data
acquisition device 1113 such as a handheld computer. The mobile
data acquisition device 1113 may also act as the transmitter 1104
and receiver 1105. If the pipe liner 1102 containing slurry or
other abrasive mixtures 1114 wears to a depth 1115 such that the
reflector 1101 is lost, the receiving antenna 1105 will no longer
realize the signal from the transmitting antenna 1104. This loss of
signal indicates that the amount of wear associated with reflector
depth 1103 has occurred. The transmitting antenna 1112 may be
replaced with a wired connection to the data acquisition device
1113.
[0040] The same technique shown in FIG. 11 may be used to monitor
wear in non-ferrous haul truck bed liners in the same manner
described to monitor pipe liners 1102. In this embodiment, said
pipe wall 1108 is a haul truck bed.
[0041] The same technique shown in FIG. 11 may also be used to
monitor wear in hoses in the same manner described to monitor pipe
liners 1102. In this embodiment, the pipe wall 1108 is absent and
the PCB 1106 is mounted to the outside of the hose, represented in
FIG. 11 by the pipe liner 1102.
[0042] Remote Recessed Reflector Antenna
[0043] In certain embodiments of the present disclosure, a Remote
Recessed Reflector Antenna (R.sup.3A) design that enables
conductive and non-conductive surfaces to transmit information via,
for example, a radio frequency antenna is used for data
transmission. The R.sup.3A is recessed into at least one of the
conductive and non-conductive surfaces such that surface topography
is not affected. This is accomplished through the use of a recessed
cavity that is covered with a dielectric material such as, for
example, Polytetrafluoroethylene (PTFE) available under the name
Teflon.RTM.. According to the exemplary R.sup.3A design, the
surface is not functionally or aesthetically hindered by the
presence of a radio transmitter and the transmitter is protected
from the environment outside of a cavity in which the transmitter
is recessed. In most prior-art arrangements, both the antenna and
the antenna cover protrude from the surface. Objects that can host
the R.sup.3A include, for example, flat and rounded surfaces that
are traveled or subject to abrasion by the environment, or
aerodynamic forces. The R.sup.3A design is mounted in the surfaces
of the tire which are least exposed to abrasion, such as the metal
support rings, henceforth referred to as "chassis," that are
commonly embedded in the tire during manufacturing.
[0044] In other embodiments, data transmission may also be
accomplished by the use of a conventional, non-recessed antenna if
the surface it is mounted on is not subject to abrasion or other
forces. The antenna may be encapsulated or otherwise covered with
materials that will best withstand the abrasion. Teflon is an
example of one material that may be well suited since Teflon has
low surface friction; is rigid, and does not significantly
attenuate radio frequency transmissions. Small gaps around covers
made of materials such as PTFE, may be sealed from moisture using
epoxy or other suitable sealants. The size of the aperture used for
wireless transmission must be minimized to best protect the antenna
and associated circuits. One or more antennas may be implemented
for this application, based on the need to radiate and receive
signals in multiple directions.
[0045] FIG. 12 illustrates a transmission system using remote dual
antennas with recessed reflectors in accordance with an exemplary
embodiment. An antenna 1201, series and shunt tuning components
1202 and a cable connector 1203 are mounted on a circuit board 1204
that is positioned in an antenna cavity 1205 with two mounting
holes 1206 aligned with threaded screw holes 1207 in a bottom
region of the antenna cavity 1205. The bottom sides of the two
screw holes 1206 in the circuit board 1204 have exposed annular
rings 1208 that are conductively bonded to a steel surface of the
bottom region of the cavity 1205 using an electrically-conductive
compound. This conductive joint between a grounded circuit board
1204 annular rings 1208 extends the circuit board 1204 ground plane
into a steel chassis 1216. This overall ground plane acts as the
reflector for the antenna. Currently, the antennas are mounted on
the edges of flat corner surface reflectors. Mounting the antenna
1201 on flat surface corner reflectors is not possible because the
surfaces 1209 are `wear-surfaces` (the antenna 1201 would be
immediately destroyed) and the surfaces are contoured such that
they have no corners. Recessing the antenna 1201 into the surface
prevents it from being destroyed by compression forces and abrasion
in the tire.
[0046] The antenna 1201 and the circuit board 1204 are further
protected with a cover 1210 formed of a material such as Teflon
that fills the cavity 1205 in front of the antenna 1201 and that is
attached by means of two screws 1211. Connectors 1203 are attached
to RF cables 1212. RF cables 1212 carry signals to and from the
transceiver and processing circuit board 1213. Dimensions of cavity
1214 allow the radiation pattern 1215 to be ninety degrees (or
greater, by means of altering these dimensions 1214, when
practical). This set of cavity dimensions 1214 is specific to this
example and may be altered, as required, for similar embodiments of
this disclosure.
[0047] Redundant Transceiver Wear Sensor for Non-Ferrous Material
Wear Sensing
[0048] FIG. 13 illustrates a wear-path of a tire. The wear-path is
defined as the path from a surface of a new tire to a wear-out or
damage limit that is to be monitored. Exemplary embodiments
disclose a novel Redundant Transceiver Tire Wear Sensor with Remote
Recessed Reflector Antenna (RTTWS-R.sup.3A) design that enables
tires to automatically report wear, tear or rupture status over
their life-cycle. This disclosure is, however, not limited to use
in tires and may be utilized in any equipment that has wear
surfaces that may benefit from wear monitoring.
[0049] In a typical embodiment, the RTTWS-R.sup.3A implementation
process begins by defining the wear paths on tires that are to be
monitored. Since each tire has unique characteristics, the
wear-paths to be monitored differ in both location and wear depth.
Wear rate at different points on the tires may vary based on the
tires engagement with a ground surface. For example, a small tire
may only require one wear-path to be monitored while larger tires
may require multiple paths or wear-depths (i.e., distance from new
surface to wear-out limit) to be monitored. According to exemplary
embodiments, wear depth monitoring is accomplished for each
wear-path by embedding, for example, transducers at intervals along
the wear-path. As tire surfaces wear reaches a transducer, its
characteristics are altered. According to exemplary embodiments,
the RTTWS-R.sup.3A implementation process includes any type of
transducer to detect wear on the tire. The use of resistors as
transducers is given here as an example. As a tire rotates, the
part of the tire that contacts the road surface may deflect due to
the weight of the vehicle. Such deflection could cause the
alignment of the transducers, and particularly the parabolic
reflectors, to deviate enough to cause an error in the wear-depth
calculation. To prevent this, an accelerometer is used to determine
the position of the tire with respect to the road surface. Signals
are sampled with the wear area to be sampled is not in contact with
the road surface.
[0050] FIG. 14 illustrates a wear path monitoring circuit in
accordance with an exemplary embodiment. Although this application
is not limited to a specific type of transducer, the use of
stainless steel wires and resistor pairs (i.e., redundant
resistors) for monitoring is disclosed herein as an example. A
first wire pair SSW1a/SSW1b is embedded nearest an outer wear
surface. Additional wire pairs SSW2a/SSW2b through SSWna/SSWnb are
equally spaced apart along the wear path. When a tire surface wears
down or is damaged to a wire in a pair such as, for example, the
wire pair SSW2a/SSW2b, the combinatorial resistance changes. The
change in resistance indicates to a processing device that the wear
depth for the wire pair has been reached. In a typical embodiment,
the processing device may be, for example, a computer, a processor,
a microcontroller, and the like. Although not shown in the wear
path monitoring circuit, the redundancy may be increased, from
pairs to groups, by adding more wires. This will decrease the
probability of false indications due to defective wire failures.
More redundancy may be added by independently returning ground
wires to the circuit board independently.
[0051] According to exemplary embodiments, the use of redundant
transducers and traces improve the monitoring reliability of the
sensors. Single component, connection or trace failures resulting
from defects in manufacturing, temperature extremes, shock or
vibration of the operating environment are detected and compensated
for in the processing circuitry. For example, if R1a and R1b are
the same value and the parallel combination of R1a and R1b through
wire pair SSW1a/SSW1b equals the value of R1, the analog voltage
detected at the an input of the processing device is V/2. If a
failure of wire SSW1a or wire SSW1b or a connection or wiring to
either of these resistors results, due to a manufacturing, material
fault, temperature extremes, shock or vibration, one of the
resistors will be omitted from the circuit. This will result in the
resistance of R1 being 1/2 the resistance of the remaining
connected resistor (R1a or R1b). The voltage detected at the input
will then be V/3. This voltage level will indicate to the processor
that the failure may not be related to wear. If the voltage level
is due to wear, it will not make a difference. The other wire in
the pair will soon be removed by wear. Until both wires in the pair
are faulted, the wear-point will not be considered to have been
reached. In sensors that do not have redundancy, failures in any of
the traces or transducer would incorrectly indicate that the wear
point was reached.
[0052] FIG. 15A-15C illustrate physical implementation of the
sensors within the tire in accordance with an exemplary embodiment.
The physical implementation of the sensor wires 1501 and
communication wires 1502 may be accomplished by embedding the
sensor wires 1501 and the communication wires 1502 in the tread
during a vulcanization process. A communication element 1503 may be
installed in a tire 1504 inside of a tire componentry such as, for
example, a chassis 1505 during a manufacturing process, prior to
vulcanization, or optionally outside of the tire componentry in the
tread during the vulcanization process. The physical paths of the
circuitry and communication cable may be perpendicular 1506 to the
chassis 1505 and/or at an angle to the chassis 1505. In some
embodiments, the tire 1504 may be embedded with a single wire pair.
In other embodiments, the tire 1504 may be embedded with multiple
wire pairs. For exemplary illustration, numerous wire pairs are
shown in FIG. 15A-15B.
[0053] The redundant wire pairs SSW1a 1507, SSW1b 1508, SSW2a 1509,
SSW2b 1510, SSWna 1511 and SSWnb 1512 are shown with an exaggerated
scale and layout in a small segment of a tire. Wires are routed
within the tread such that the steel flexes within its elastic
limits to avoid metal fatigue, allowing the wires to remain intact
until they are broken by tire wear. All sensor wires route to
processing element 1513. In a typical embodiment, data is formed
into packets and transmitted wirelessly 1514 inward towards at
least one of a center of the tire, outward from the center of the
tire, or radially out of the tire, to a host which is generally
located on a vehicle. FIG. 15A-15C illustrate three different
depths of wire sensors. Exemplary embodiments disclose
implementations from one sensor wire pair to any number or wear
depths and sensor array configurations.
[0054] FIG. 16 illustrates a wear path monitoring circuit in
accordance with an alternate embodiment using resistor pairs (i.e.,
redundant resistors). T1 is embedded nearest an outer wear surface
with T2 through Tn equally spaced along the wear path. Tn is
located closest to the wear limit. When a tire surface wears down
to a resistor pair such as, for example, R1a and R1b, the
combinatorial resistance changes. The resistance can be reduced or
shorted (if filled with mud) or increased or open (if the
connections or resistor are damaged or broken). The change in
resistance indicates to the processing device that the wear depth
for the resistor pair has been reached. Although not illustrated,
the traces may also be made redundant by use of more traces
installed on flexible circuit board layers to decrease the
probability of false indications due to faulty trace failures.
[0055] Redundant transducers and traces improve monitoring
reliability of the sensors. Single component, connection or trace
failures resulting from defects in manufacturing, extremes in
temperature, shock or vibration of the operating environment are
detected and compensated for in the processing circuitry. For
example, if the parallel combination of R1a and R1b equals the
value of R1, the analog voltage detected at the processor input is
V/2. If a failure of R1a, R1b or a connection or trace path to
either of these resistors results, due to a manufacturing fault,
temperature extremes, shock, or vibration, one of the resistors is
omitted from the circuit. This results in the resistance of R1
being 1/2 the resistance of the remaining connected resistor such
as, for example, R1a or R1b. The voltage detected at the input will
then be V/3. This voltage level will indicate to the processing
circuitry that the failure may not be related to wear. If the
voltage level is due to wear, it will not make a difference. The
other resistor will soon be removed by wear. Until both resistors
in the pair are faulted, the wear-point will not be considered to
have been reached. In sensors that do not have redundancy, failures
in any of the traces or transducer will incorrectly indicate that
the wear point was reached.
[0056] FIG. 17A-17C illustrate physical implementation of the
sensors within the tire in accordance with an alternate embodiment.
The physical implementation of the sensor wires 1701 such as, for
example, wires and redundant resistor pairs imbedded in flexible
PCB and communication wires 1702 to the processing and
communication element 1703 may be accomplished by embedding them in
the tread during the vulcanization process as is presently done
with RFID circuitry. The processing and communication element 1703
may be installed inside the tire component surfaces 1706 (e.g., the
"chassis") during the manufacturing process prior to vulcanization,
or outside of the tire componentry (the "chassis") and in the tread
1704 and installed during the vulcanization process. The physical
paths of the circuitry and communication cable may be perpendicular
to 1706 and/or at an angle to the chassis 1706.
[0057] The transducers T1 1707, T2 1708, and Tn 1709 are shown with
exaggerated scale and layout in a small segment of a tire. Wires
are routed within the tread to redundant resistors on flexible PCB
such that the steel and PCB flexes within its elastic limits to
avoid metal fatigue, allowing the wires and PCB mounted resistors
to remain intact until they are broken by tire wear. All sensor
wires route to processing element 1710 which can be mounted in the
tread during the vulcanization process, or outside of the tread as
shown. The data is formed into packets and transmitted wirelessly
1711 inward towards the center of the tire and/or outward from the
center of the tire or radially out of the tire to the host which is
generally located on the vehicle. The diagram shows 4 different
depths redundant wear sensors. Exemplary embodiments disclose
implementations from one sensor pair to any number or wear depths
and sensor array configurations.
[0058] From the perspective of monitoring the wear of a tire, since
there are no practical means of attaching wires from the tire to
the vehicle for communication, the application is considered to be
remote. The monitoring electronics are embedded in the rotating
tire. Sending the signals to the operator is a challenge. For the
tire, the monitoring electronics inside the tire are powered by a
battery. These batteries are to be specified to operate the
monitoring circuits for the lifetime of the tire. When the tire is
installed on the machine, the monitoring processor may be activated
(awakened) from a `deep sleep` mode and remains active for the life
of the tire or may only be active when the tire rotates.
[0059] Referring now to power aspects for the embodiments shown and
described herein, the use of a battery with the methods and systems
of the present disclosure is optional if piezoelectric ceramic
wafers (PCW's) are implemented into the circuitry. PCW's develop
small voltages when they are subjected to vibrations that excite
them to move at their resonant frequencies. State of the art
devices have now been developed to convert these small voltages
into energy sufficient to power small sensors and transmitters.
This type of technology is being called "energy harvesting". The
currents harvested from these devices are used to charge electrical
storage devices such as capacitors, super capacitors and
potentially batteries. When sufficient energy has been stored to
read the transducers and transmit the data in a wireless packet,
the data is transmitted to the host. This disclosure may be applied
to tire wear monitoring using the tire rotation and vibration to
excite the PCW.
[0060] General Computing and Computer Programming Disclosure
[0061] Particular embodiments may include one or more
computer-readable storage media implementing any suitable storage.
In particular embodiments, a computer-readable storage medium
implements one or more portions of the processor, one or more
portions of the system memory, or a combination of these, where
appropriate. In particular embodiments, a computer-readable storage
medium implements RAM or ROM. In particular embodiments, a
computer-readable storage medium implements volatile or persistent
memory. In particular embodiments, one or more computer-readable
storage media embody encoded software.
[0062] In this patent application, reference to encoded software
may encompass one or more applications, bytecode, one or more
computer programs, one or more executables, one or more
instructions, logic, machine code, one or more scripts, or source
code, and vice versa, where appropriate, that have been stored or
encoded in a computer-readable storage medium. In particular
embodiments, encoded software includes one or more application
programming interfaces (APIs) stored or encoded in a
computer-readable storage medium. Particular embodiments may use
any suitable encoded software written or otherwise expressed in any
suitable programming language or combination of programming
languages stored or encoded in any suitable type or number of
computer-readable storage media. In particular embodiments, encoded
software may be expressed as source code or object code. In
particular embodiments, encoded software is expressed in a
higher-level programming language, such as, for example, C, Python,
Java, or a suitable extension thereof. In particular embodiments,
encoded software is expressed in a lower-level programming
language, such as assembly language (or machine code). In
particular embodiments, encoded software is expressed in JAVA. In
particular embodiments, encoded software is expressed in Hyper Text
Markup Language (HTML), Extensible Markup Language (XML), or other
suitable markup language.
[0063] Conditional language used herein, such as, among others,
"can," "might," "may," "e.g.," and the like, unless specifically
stated otherwise, or otherwise understood within the context as
used, is generally intended to convey that certain embodiments
include, while other embodiments do not include, certain features,
elements and/or states. Thus, such conditional language is not
generally intended to imply that features, elements and/or states
are in any way required for one or more embodiments or that one or
more embodiments necessarily include logic for deciding, with or
without author input or prompting, whether these features, elements
and/or states are included or are to be performed in any particular
embodiment.
[0064] While the above detailed description has shown, described,
and pointed out novel features as applied to various embodiments,
it will be understood that various omissions, substitutions, and
changes in the form and details of the devices or algorithms
illustrated can be made without departing from the spirit of the
disclosure. As will be recognized, the processes described herein
can be embodied within a form that does not provide all of the
features and benefits set forth herein, as some features can be
used or practiced separately from others. The scope of protection
is defined by the appended claims rather than by the foregoing
description. All changes which come within the meaning and range of
equivalency of the claims are to be embraced within their
scope.
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