Device for detecting wear of replaceable components

A device for detecting wear of a wear member composed of electrically resistive material. The wear member comprises at least two electrodes separated from each other, where each electrode overlies, or is embedded in, an outer surface of the electrically resistive material. One of the electrodes is connected to a resistor at a measurement node to form a resistive voltage divider. A voltage measurement device measures a change in voltage at the measurement node, where the change is voltage is indicative of the degree of removal of resistive material from a face of the wear member and where the change in voltage is continuously variable and not limited to discrete wear levels.

FIELD

This disclosure relates to a device for detecting wear of an electrically resistive wear member.

BACKGROUND

In off-road vehicles and equipment, some portions of the vehicle or implements may wear from contact with harvested agricultural materials, mined ore, mined materials, gravel, crushed stone, concrete or asphalt, ceramics, steel, ground, clay, sand, abrasive materials, or other materials. The off-road vehicles and equipment may use replaceable wear members from wear-resistant, durable or sacrificial materials to protect underlying structural members. The wear members are sometimes located in inaccessible locations in the equipment, implement or machinery that is difficult to inspect without incurring significant labor or maintenance costs. Accordingly, there is a need to continuously monitor wear members for signs of wear and worn or alert the operator when or that the wear member may require replacement.

SUMMARY

In accordance with one embodiment, a device for detecting wear of a wear member composed of electrically resistive material. The wear member comprises at least two electrodes separated from each other, where each electrode overlies, or is embedded in, an outer surface of the electrically resistive material. One of the electrodes is connected to a resistor at a measurement node to form a resistive voltage divider. A voltage measurement device measures a change in voltage at the measurement node, where the change is voltage is indicative of the degree of removal of resistive material from a face of the wear member and where the change in voltage is continuously variable and not limited to discrete wear levels.

DETAILED DESCRIPTION

As used in this document, adapted, configured, or arranged can be regarded as synonymous terms. Adapted, configured or arranged mean that a device, processor, interface, module, or other element is structured, designed, or programmed with electronics hardware, software, or both to facilitate or achieve a functional result or outcome that is specified. For example, a data storage device may store software, data, libraries, or software instructions that can be executed or processed by an electronic data processor to achieve a certain functional result or identified outcome.

A wear member may relate to any member that wears from engagement with a contact member, material, or the ground, among other objects or possibilities. For example, ground-engaging wear members include by are not limited to tracks for a tracked vehicle, a blade for a dozer or grader, a bucket for a loader or excavator, a drag chain or drag bar for a row unit of a planter, a ground-engaging wear plate or skid member of a combine or harvester head assembly. Other wear members may wear from interaction with harvested material such as a cutter, a blade, teeth, concave grates of combines, concave spacers of combines, impact plates or impact members of mass flow sensors on combines or harvesters, or other components of vehicles, implements, or heavy equipment. Still other wear members may wear from interaction with various components of assemblies, systems, or parts of vehicles, machinery or implements, such as axial bearings, radial bearings or thrust bearings. Although the wear member is illustrated as a block or substantially rectangular, the wear member may have virtually any geometric shape, such as substantially elliptical, substantially annular, substantially polygonal, substantially polyhedral, or otherwise.

In accordance with one embodiment illustrated inFIG.1, a wear detection device11for detecting wear of a wear member41comprises a wear member41and associated measurement circuitry. The wear member41is composed of electrically resistive material173, alone or in conjunction with a dielectric substrate. The wear member41comprises at least two electrodes (130,131) separated from each other, where each electrode (130,131) overlies, or is embedded in, an outer surface110of the electrically resistive material173. The electrically resistive material between a first electrode130and a second electrode131provides a resistance (175,176) or variable resistance that varies with wear of the wear member41.

In one embodiment, a resistor152is connected in series with the wear-variable resistance (175,176) between the first electrode130and the second electrode131. The first resistor152and the wear-variable resistance (175,176) collectively form a resistive voltage divider. As illustrated inFIG.1, the first electrode130is connected to a resistor152at a measurement node129of the resistive voltage divider. In one example, the first electrode130may be coupled to receive electrically energy from a positive direct current voltage terminal150; the second electrode131may be coupled to ground or a negative direct current voltage terminal154. Meanwhile, the measurement node129is coupled to an analog-to-digital converter122to provide an analog observed measurement of the observed voltage, observed current or corresponding observed resistance of the resistance (175,176) to an input of the analog-to-digital converter122.

In some examples, the first electrode130and second electrode131are on the same face of the outer surface110of wear member as the wear surface160that contacts a contact member132. In other examples, one or more electrodes may be mounted on other surfaces for protection or isolation from the contact member132to avoid damage from the contact member132, to better measure surface wear, or for other reasons.

A measurement device or circuitry measures a change in observed voltage, current or resistance at the measurement node129, where the change in the observed voltage, current or resistance is indicative of the degree of removal of resistive material173from a face of the wear member41and where the change in observed voltage, current or resistance is continuously variable and not limited to discrete wear levels. As illustrated inFIG.1, the measurement device (e.g., voltage measurement device) comprises the combination of an electronic data processor120, a data storage device125, an analog-to-digital converter122, and a communications interface124that communicate to each other via a data bus127, where a user interface140can communicate with the communications interface124via a transmission line, wireless communications link (e.g., of wireless transceivers), or vehicle data bus127.

A resistive voltage divider is based on a first resistor152(e.g., a resistor of fixed value or discrete resistive component) that is coupled between the positive voltage direct current terminal150and the first electrode130and a second resistor of wear-variable resistance (175or176) that is formed by the resistive material173between the first electrode130and the second electrode131, where the second electrode131is grounded or connected to a negative voltage direct current terminal154. The wear-variable resistance (175or176) has variable resistance that varies with wear or time, such as a first wear-variable resistance175(e.g., new resistance) and a second wear-variable resistance176(e.g., worn resistance).

In other embodiments, a Wheatstone bridge may be used instead of a simple voltage divider or active components such as operational amplifiers may be used to amplify and condition signals.

In one embodiment, the electrodes (e.g.,130,131) are embedded in the electrically resistive material173. The electrically resistive material173may comprise carbon particles, graphite particles, or other electrically conductive particles, such as metal, metal oxide, or metal alloy fillers embedded in a plastic matrix, a polymeric matrix, or a ceramic matrix. The plastic matrix, polymeric matric or ceramic matrix comprises a binder or curable resin. For example, the electrically resistive material173may comprise a carbon composite material of known conductivity or resistance. The electrical resistivity may be measured as resistance per unit volume (e.g., ohms per millimeter squared), resistance per linear distance (e.g., ohms per millimeter) between the electrodes, or both. If the resistive material173has an isotropic or uniform resistance that is proportional to distance, wear of the wear member can be detected as a change in observed resistance, observed voltage or observed current.

In some examples, the resistivity of wear member41is uniform in all directions and has isotropic resistivity throughout the volume. In other examples or alternate embodiments, the resistivity of the wear member41may be fabricated with a non-uniform resistivity or anisotropic resistivity, such as greater resistance near the wear surface160or geometrically shaped resistive sections that are embedded in a dielectric material, to enable greater sensitivity to wear or certain wear profiles of the wear member.

As the wear face or wear surface121of wear member41wears from contact of a contact member132or other material with the wear surface121, the electrically resistive material173is lost or removed from the wear member41, such as a wear surface121. In a first wear state or first wear level when the face is not worn, the electrical current between the electrodes takes a first path (e.g., direct path171indicated by dotted line inFIG.1) of least resistance through the electrically resistive material173that is associated with a first wear-variable resistance175. However, in a second wear state or second wear level when the face is partially worn, the electrical current between the electrodes can no longer take the first path (e.g., direct path171indicated by dotted line171or dashed line170) of least resistance through the electrically resistive material173because the electrically conductive material associated with the first path is missing or worn away. In the second wear state or second wear level when the face is partially worn, the electrical current between the electrodes is forced to take a longer second path (e.g., curved path or indirect path (172) of least resistance through the electrically resistive material173that is associated with the second wear-variable resistance176. As illustrated inFIG.1, the first path is shorter than the second path through the electrically resistive material173, or conversely, the second path is longer than the first path.

The wear-variable resistance (175,176) can be configured to change a material detectable amount based on wear member dimensions and electrode placement and dimensions. In an alternate embodiment, the geometric configuration of the electrically resistive material (e.g.,173) may be structured as a thin film on, at, under or associated with the wear surface (e.g.,160) of the wear member (e.g.,41). In one example of an alternate embodiment, the wear member has an electrically resistive wear volume configured as a film and sheet resistance is in ohms per meter squared (ohms/m2). As wear occurs, the wear-variable resistance will increase because the surface area increases or the film thickness is reduced, or both. The thin film resistive section is embedded in or at the surface of a dielectric body such that the wear member in the aggregate may be considered to have an anisotropic resistance profile, even if the resistance profile within the thin film resistive section is isotropic.

In another alternate embodiment, the geometric configuration of the electrically resistive material (e.g.,173) may be structured as a substantially cylindrical volume of electrically resistive material, a substantially polyhedral volume of electrically resistive material or as another geometric-shaped volume of electrically resistive material that varies in electrically resistance with wear. For example, the wear member (e.g., substantially annular, polyhedral, conical, spherical, hemispherical, pyramidal, or cylindrical outer shape) is configured with a substantially cylindrical volume of resistive material of linear length between two electrodes; the cylindrical volume has a substantially elliptical or circular cross-sectional area; there is a generally uniform resistivity per unit volume of the cylindrical volume. Accordingly, as the radius or diameter of the cylindrical volume is decreased by wear of the wear member, the resistance increases. In the alternate embodiment, the geometric resistive volume, such as the substantially cylindrical volume, can be embedded in a dielectric body or dielectric substrate of the wear member to result in an anisotropic resistance profile of the wear member in the aggregate, even if the resistance profile within the substantially cylindrical volume is isotropic.

InFIG.1, the electronic data processor120, data storage device125, analog-to-digital converter122, and communications interface124can communicate with each other via a data bus127. Further, in an alternate configuration if the user interface140is coupled to the data bus127, the electronic data processor120, data storage device125, analog-to-digital converter122, communications interface124, and the user interface140can communicate with each other via the data bus127.

In one embodiment, the communications interface124may communicate with a controller174, a user interface140or both via transmission lines, wirelessly or a vehicle data bus127, for example. The controller174and its communications line is shown in dashed lines to indicate that the controller174and the communications line are optional. For example, the controller174may be a controller174associated with an actuator for controlling the settings on a machine, vehicle, implement or equipment to compensate for wear in the wear member41of its mechanical moving parts, such as cutters, threshers, separators, sieves, grinders, or other moving parts. For example, the electronic data processor120may provide a wear level or wear level data message via the communications interface124to the controller174, such that the controller174can command an actuator: (1) to make a machine adjustment to protect the machine from damage, such as reducing or limiting a maximum rotational speed or operational torque, and/or (2) to adjust or close a gap or clearance commensurate with the wear level or wear level data message, where the wear level might be scaled to the appropriate corresponding adjustment of the gap or clearance based on the respective wear level.

An electronic data processor120may comprise a microcontroller, a microprocessor, a logic device, a field programmable gate array, an application specific integrated circuit, a digital signal processor or another electronic data processor.

InFIG.1, the data processor120regularly, periodically or occasionally senses the voltage at a first electrode130or measurement node129. When the wear member41is new, there is a direct path (171or170) between the first electrode130and the second electrode131with a new resistance as the first wear-variable resistance175. As resistive material173is worn away from a wear surface160of the wear member41, the electrical path lengthens to worn path or indirect path172with worn resistance as the second wear-variable resistance176. Because worn path distance is longer, the resistance to current flow is higher, which means that the second wear-variable resistance176is higher than the first wear-variable resistance175. Accordingly, the observed voltage or resistance measured at the measurement node129that is coupled to the analog-to-digital converter122will increase.

In one embodiment, the data processor120processes the time series of observed voltages (or equivalent observed currents) to a characterization of the wear of wear member41and generates a respective wear level or wear status data message for transmission to the user interface140, the controller174, or both. The data processor120may use reference data126to convert raw observed voltage data at the measurement node129or raw observed current data at the measurement node129to one or more of the following: (1) an increased surface distance between electrodes (130,131) using wear member resistivity data, (2) a threshold-based replacement alert for the wear member41after a certain threshold percentage, volume or displacement of material has been removed or worn away, (3) an estimated remaining useful life (RUL) of the wear member or predictive maintenance estimate of a replacement date for a wear member41or associated replacement part, (4) a compensation factor for increase in wear member surface area, and (5) compensation factor based on angle of impact or contact between material and the face of the wear member.

A communications interface124may comprise a data communications port, a transceiver or another device that supports communication with the electronic data processor120and other modules via the data bus127.

A user interface140may comprise an electronic display, a touch screen display, a panel of light emitting diodes, an indicator light, an alphanumeric display, a switch, a keypad, a keyboard, and/or a pointing device (e.g., mouse or trackball or pad).

An analog-to-digital converter122is coupled to the measurement node129. A data storage device125is arranged to store reference data126comprising reference measurement voltage versus a wear level of the wear member41. An electronic data processor120is adapted to determine the wear level or degree of removal of the resistive material173from the face of the wear member based on an observed change in the observed voltage (or its equivalent current) at the measurement node129with respect to an initial voltage or a reference voltage at the measurement node129associated with an initial wear member with a new face without any resistive material173yet removed.

A user interface140can provide a visual indicator, an audible indicator or both to a user that is indicative of the determined wear level of determined degree of removal of resistive material173from the face of the wear member, the user interface140coupled to the electronic data processor120via a communications interface124and a data bus127.

The mechanical contact member132contacts the face or wear surface121of the wear member41and the device may measure or sense the wear level or wear state in accordance with various techniques, which may be applied separately or cumulatively.

Under a first technique, the mechanical contact member132has an engaging face that contacts and engages the wear face or wear surface11of the wear member to remove the electrically resistive material173over time from the initial state of wear member41to a partially worn state of the wear member41. A partially worn state of the wear member41is associated with an observed voltage measurement (or its equivalent current measurement) within a first reference voltage measurement range between a first lower limit and a first upper limit.

Under a second technique, mechanical contact member132has an engaging face or wear surface121that contacts and engages the face of the wear member132or other material to remove the electrically resistive material173over time from the initial state of wear member41to a recommended replacement state of the wear member41. Further, the recommended replacement state of the wear member is associated with an observed voltage measurement (or its equivalent current) within a second reference voltage measurement range (or its equivalent current measurement range) between a second lower limit and a second upper limit, wherein the second reference voltage range is lower than the first reference voltage range.

Under a third technique, the mechanical contact member132has an engaging face or wear surface121that contacts and engages the face of the wear member41to remove the electrically resistive material173over time from the initial state of wear member to a fully worn state of the wear member. Further, the fully worn state of the wear member41is associated with an observed voltage measurement (or its equivalent current) within a third reference voltage measurement range (or its equivalent current measurement range) between a third lower limit and a third upper limit, wherein the third reference voltage range is lower than the first reference voltage range and the second reference voltage range.

The wear detection device111ofFIG.2is similar the wear detection device11ofFIG.1, except the wear detection device111ofFIG.2has a plurality of primary electrodes (232,233,234,235) spaced apart from each other on the outer face210and a secondary electrode231on an opposite face195; each of the primary electrodes (232,233,234,235) is associated with a respective separate resistive zone or region (236,237,238,239) between ones of the primary electrodes (232,233,234,235) and the secondary electrode231. Like reference numbers inFIG.1andFIG.2indicate like elements or features.

Further, a resistive network241is coupled to the primary electrodes (232,233,234,235). In one configuration, the resistive network241incorporates one or more resistors and forms a set of resistive voltage dividers (71,72,73,74) to provide a different operational voltage at each corresponding measurement node129. However, in alternate embodiment, the resistive network241and associated resistive voltage dividers can be deleted. The resistive network241is indicated by the dashed lines inFIG.2because it is optional, as well as the resistors shown within the resistive network241for illustrative purposes.

In one embodiment, an analog multiplexer242is coupled to the primary electrodes (232,233,234,235) via the resistive network241to select respective ones of the primary electrodes (232,233,234,235) or their respective measurement nodes (51,52,53,54). In another embodiment, the analog multiplexer242is coupled directly to the primary electrodes (232,233,234,235), without any intervening resistive network241, to select respective ones of the primary electrodes (232,233,234,235), or their respective measurement nodes.

A data storage device125is arranged to store reference data126, such as reference measurement voltage versus a wear level of the wear member for each corresponding resistive zone or region (236,237,238,239), or a reference current versus wear level of the wear member for each corresponding resistive zone or region (236,236,238,239).

In one embodiment, inFIG.2the electronic data processor120is adapted to determine the wear level or degree of removal of the resistive material from one or more wear faces or wear surfaces of the wear member141based on any observed change in voltage or current at the respective measurement nodes (51,52,53,54) with respect to each initial voltage or each reference voltage (or its equivalent initial current or reference current) for the corresponding resistive zone at the respective measurement node (51,53,53,54). Each resistive zone is associated with a separate wear level range and wherein there are at least two respective wear level ranges, where within each wear level range the wear level is continuously variable and not limited to discrete wear levels.

A user interface140is arranged to provide a visual indicator, an audible indicator or both to a user that is indicative of the determined wear level of determined degree of removal of resistive material from the face of the wear member141, the user interface140coupled to the electronic data processor120via a communications interface124and a data bus127.

As illustrated inFIG.2, a wear detection device111for detecting wear of a wear member comprises an electrically resistive material (within resistive regions236,237,238,239) that has one or more wear surfaces for engaging corresponding mechanical contact members (81,82,83) and an outer surface separate210from the wear surfaces.

Primary electrodes (232,233,234,235) are spaced apart from each other on the outer surface210. A secondary electrode231is positioned on an opposite surface to the outer surface210of the electrically resistive material within resistive regions (236,237,238,239). Resistive regions are separated from each other. Each of the resistive regions extends in the electrically resistive material between ones of the primary electrodes (232,233,234,235) and the secondary electrode231. Although the wear member141has secondary electrode231which extends approximately the length of the wear surface160of wear member inFIG.2, the secondary electrode231may have other shapes and lengths that fall within the scope of this disclosure. As illustrated, the secondary electrode231is electrically connected to ground or the negative direct current terminal.

Each primary electrode (232,233,234,235) and the secondary electrode231form a resistor or resistance (91,92,93,94) that is coupled to a restive network241or a first resistor61, a second resistor62, a third resistor63or a fourth resistor64within the resistive network241. The first resistance region236, between a first primary electrode232and the secondary electrode231, is associated with the first resistance91. The second resistance region237, between a second primary electrode233and the secondary electrode231, is associated with the second resistance92. The third resistance region238, between a third primary electrode234and the secondary electrode231, is associated with the third resistance93. The fourth resistance region239, between a fourth primary electrode235and the secondary electrode231, is associated with the fourth resistance94. The resistance regions (236,237,238and239) are separated from each (and electrically isolated from each other) other by dielectric regions84or a dielectric substrate of the wear member.

A first resistor61and the first resistance91collectively form a first resistive voltage divider71. A first measurement node51is at the junction of the first resistor61and the first resistance91; the first measurement node51is coupled to a mux input245of the analog multiplexer242.

A second resistor62and the second resistance92collectively form a second resistive voltage divider72. A second measurement node52is at the junction of the second resistor62and the second resistance92; the second measurement node52is coupled to a mux input245of the analog multiplexer242.

A third resistor63and the third resistance93collectively form a third resistive voltage divider73. A third measurement node53is at the junction of the third resistor63and the third resistance93; the third measurement node53is coupled to a mux input245of the analog multiplexer242.

A fourth resistor64and the fourth resistance94collectively form a fourth resistive voltage divider74. A fourth measurement node54is at the junction of the fourth resistor64and the fourth resistance94; the fourth measurement node54is coupled to a mux input245of the analog multiplexer242.

The resistive zone or resistive region, between each primary electrode (232,233,234,235) and the secondary electrode231, may comprise a substantially cylindrical zone, polyhedral zone, annular zone, pyramidal zone, or conical zone embedded within a dielectric block and where the resistive zone has an isotropic resistance or an anisotropic resistance. The positive direct current terminal (e.g., Vref) can feed each of the resistive voltage dividers (71,72,73,74) within the resistive network241. Accordingly, the separate resistive voltage dividers (71,72,73,74) and can have observed voltages or observed currents separately and independently measured by the data processor120and consequently, separate resistances calculated for a first resistance91, a second resistance92, a third resistance93and a fourth resistance94for the first resistive zone236, the second resistive zone237, the third resistive zone238, and the fourth resistive zone239, respectively.

The above resistances (91,92,93,94) are variable with wear and proportional to wear of the resistive region (236,237,238,239), between the primary and secondary electrodes. The wear level of each resistive region (236,237,238,239) is associated with one or more contact members (81,82,83) that are shown in phantom as a first contact member81with its wear extending rightwards into the first resistive zone236and towards (but not yet reaching) the second resistive zone237, where the first contact member81has worn through the first resistive zone236as illustrated inFIG.2. A second contact member82is associated with the third resistive zone238with its wear extending into and out of the plane of the sheet ofFIG.2. A third contact member83is associated with the fourth resistive zone239with its wear extending leftward partially into the fourth resistive zone239. In an alternate embodiment, as few as one contact member of the first contact member81, the second contact member82or the third contact member83may be used; the other wear members may be omitted.

A resistive network241comprises resistive voltage dividers coupled to the primary electrodes (232,233,234,235) at respective measurement nodes129.

A measurement device (e.g., voltage measurement device) measures an observed voltage change, observed current change or observed resistance change at one or more of the measurement nodes129where each observed voltage, current or resistance change is indicative of a respective wear level or the respective degree of removal of resistive material from a face or one or more engaging surfaces of the wear member141. The observed voltage change, observed current change, or corresponding observed resistance is continuously variable and not limited to discrete wear levels.

In the resistive regions (236,237,238,239) the electrically resistive material of the wear member141further comprises a second surface opposite33(e.g., second face) the first surface31(e.g., first face) of the wear member141, where the second surface33is arranged for engaging a third mechanical contact member83; wherein the voltage measurement device111is configured to measure a first wear level associated with the first surface31of the wear member141and a second wear level associated with the second surface33of the wear member141.

In one embodiment, the first wear level of the first surface31is generally correlated to the second wear level of the second surface33. However, in other embodiments, the first wear level of the first surface31is independent of the second wear level of the second surface33.

An analog multiplexer242is coupled to the primary electrodes (232,233,234,235) via the resistive network241to select respective ones of the primary electrodes (232,233,234,235) or their respective measurement nodes (51,52,53,54). The analog multiplexer242enables the resistance between any two electrodes to be measured, giving a more detailed view of the wear levels for one or more wear surfaces (31,33) of the wear member141. The analog multiplexer242can selectively connect a positive voltage terminal150(e.g., a reference voltage or Vref) to any electrode or set of electrodes to obtain measurements of observed resistance, observed voltage or observed current at one or more measurement nodes (51,52,53,54). By only enabling a single electrode at a time, issues with voltage variation between electrodes other than the two in use can be eliminated or reduced.

In an alternate embodiment, the multiplexer242is replaced with a switching network that can enable the observed resistance, voltage or current between any two electrodes to be measured, where the electronic data processor120can control the active state or inactive state of each switch within the switching network to enable measurements of observed resistance, voltage or current.

A data storage device125is coupled to the electronic data processor120via a data bus127. The data storage device125can store, retrieve, access, write, modify, delete, or otherwise manipulate reference measurement voltage versus a wear level of the wear member141for each corresponding resistive zone or region, or reference measurement current versus wear level of the wear member141for each corresponding resistive zone or region.

In one embodiment, an electronic data processor120is adapted to determine the first wear level or degree of removal of the resistive material of the resistive regions (236,237,238,239) from the first surface31of the wear member141and to determine the second wear level or degree of removal of the resistive material from the second surface33of the wear member141based on any observed change in voltage or current at the respective measurement nodes (51,52,53,54) with respect to each initial voltage or each reference voltage for the corresponding resistive zone at the respective measurement node.

In one embodiment, mux inputs245of an analog multiplexer242are coupled to the resistive voltage network241. For example, mux inputs245are coupled to measurement nodes (51,52,53,54), which are in turn coupled to the primary electrodes (232,233,234,235). Accordingly, the multiplexer245can select mux inputs245to provide to the mux output244, where the mux inputs245can select to measure the observed voltage, current or resistance associated with the first measurement node51or first resistance91, the second measurement node52or the second resistance92, the third measurement node53or the third resistance93and the fourth measurement node54or the fourth resistance94. Each resistance is associated with corresponding primary electrodes (232,233,234,235) or their respective measurement nodes129. The data processor120controls the multiplexer241to provide or select one or more mux inputs245to a mux output244, such as a sequence of observed measurements (e.g., voltage, current or resistance) on mux inputs245to the mux output244over a series of clock cycles or successive time sampling periods.

In one embodiment, the analog multiplexer242or its mux output244is coupled to a measurement interface243that scales, adjusts, compresses, amplifies, or inverts measurement levels; matches impedance, holds samples; and/or converts current measurements to voltage measurements, or vice versa; of the analog data provided at the mux output244to prepare the data for the analog-to-digital converter124, such as to fall within a range of target analog input voltages, target analog input currents, or the like. The measurement interface243is shown in dashed lines to indicate that it is optional.

A data storage device125is arranged to store reference data126comprising reference measurement voltage versus a wear level of the wear member141for each corresponding resistive zone (236,237,238,239), or reference measurement current versus wear level of the wear member141for each corresponding resistive zone.

In one embodiment, the electronic data processor120is adapted to determine the wear level or degree of removal of the resistive material from the first surface of the wear member based on any observed change in voltage or current at the respective measurement nodes (51,52,53,54) with respect to each initial voltage or each reference voltage (or its equivalent initial current or reference current) for the corresponding resistive zone at the respective measurement node (51,52,53,54). Each resistive zone (236.237,238,239) is associated with a separate wear level range and wherein there are at least two respective wear level ranges, where within each wear level range the wear level is continuously variable and not limited to discrete wear levels.

FIG.3is flow chart of a method for detecting wear level of an electrically resistive wear member in accordance with the device ofFIG.1,FIG.2or otherwise. The method ofFIG.3begins in step S410.

In step S410, an electrical circuit is established through an electrically resistive material173of a wear member41, or resistive regions (236,237,238,239) of wear member141, between at least two electrodes via an electrical path that is susceptible to change (e.g., lengthening) as the electrically resistive material173, or one or more resistive regions, is worn away by contact with an engaging contact member or other material that contacts the wear member.

Step S410may be carried out in accordance with various examples, which may be applied separately or cumulatively. In a first example,FIG.1features a fixed circuit by design that measures the observed voltage, observed current or corresponding observed resistance of the electrically resistive material173between the first electrode130and the second electrode131.

In second example,FIG.2features a data processor120that can control a multiplexer242to select which primary electrodes (232,233,234,235); hence which resistances (91,92,93,94) of the wear member141, will be measured or sampled at one or more measurement nodes (51,52,53,54). The multiplexer242can select or poll individual measurement nodes (51,52,53,54) in a predetermined sequence or in a random order; hence, corresponding resistances of the wear member141, for sensing observed voltage, observed current or observed resistance.

In a third example, a data processor120can control a switching network (that replaces the multiplexer) to select or poll individual measurement nodes (51,52,53,54); hence, which resistances of the wear member, will be measured or sampled as measurement nodes.

In a fourth example, a logic gate or other digital circuits may be used to selectively sample or poll the measurement nodes (51,52,53,54) or different primary electrodes (232,233,234,235).

In a fifth example, outputs of electronic data processor120selectively supply the positive direct current bus (e.g., Vref) to the resistive network241or to one or more voltage resistive voltage in the resistive network241, such as different ones or selected ones of the voltage resistive dividers (71,72,73,74) in a sequence or serial activation of each resistive voltage divider.

In step S420, a measurement device (e.g., voltage measurement device) senses an observed voltage or current between two electrodes that is correlated with a wear level of the electrically resistive material173or resistive region (236,237,238,239) between the at least two electrodes. For instance, the observed voltage or observed current is a function of the change in the resistivity of the electrically resistive material173as some of the electrically resistive material173is worn away and forces the electricity to take a less direct path between the two electrodes.

In step S430, the electronic data processor120or user interface140generates a signal or data message for alert or control based on the measured material wear or wear level, which can change is continuous manner, as opposed to in discrete wear levels or steps.

Step S430may be carried out in accordance with various techniques, which may be applied separately or cumulatively.

Under a first technique, the electronic data processor120generates a data message to control an actuator to compensate for wear of a wear member (41or141) by adjusting the clearance between members of mechanical system in which the worn wear member resides or is incorporated. For example, the electronic data processor120may generate a data message to control an actuator in a machine such as a grain harvester or combine to adjust the clearance between a concave and a rotor based on wear level of a wear member (e.g., concave, concave spacer, concave cover, or concave grate; or bearing, radial bearing, or axial thrust bearing) associated with the concave and rotor. Alternately, the electronic data processor120may limit the maximum ground speed of the harvester or combine during harvesting or a maximum threshing speed of the separator motor or concave drive motor where the wear member (e.g., bearings) are indicated at or above a threshold level requiring replacement.

Under a second technique, the electronic data processor120generates a data message to compensate for wear of a wear member associated with a sensor reading, such as changing the observed value of sensor reading to compensate for wear in the wear member that is incorporate into the sensor. For example, the electronic data processor120may generate a data message to compensate for observed grain yield or observed mass flow rate in conjunction with a worn wear member (e.g., bearing, radial bearing, axial thrust bearing, grain impact plate) to a certain wear level, such that the mass flow sensor yields a consistent wear-compensated observed grain yield or consistent wear-compensated mass flow rate over the lifetime of the wear member of the mass flow sensor and the mass flow sensor itself.

Under a third technique, the electronic data processor120generates a data message to generate a wear level indicator message or alert (e.g., visual alert, indicator or alarm or audio alert indicator or alarm) to an operator or user via the user interface140. For example, the electronic data processor120generates a data message for any of the following: (1) recommend or suggest scheduling a service visit with a service technician or dealer via wireless communication (e.g., over the Internet) to replace a wear member (e.g., bearing or ground engaging wear member of a combine header) or serviceable component of a vehicle, machine or implement that is associated with the wear member; (2) automatically place an order via wireless communication (e.g., over the Internet) for a wear member or serviceable component of a vehicle, machine or implement that is associated with the wear member, (3) automatically display audio, visual or haptic output via the user interface140indicating a certain wear level of a wear member or a substantially worn level of a wear member that requires replacement.

While the disclosure has been described in detail in the drawings and foregoing description, the description shall be considered as exemplary and illustrative, rather than restrictive of the scope of protection set forth in the claims. Various illustrative embodiments have been shown and described in this document, such that any changes, variants and modifications that come within the spirit of the disclosure will fall within the scope of the disclosure and its associated claims.