Patent Application
20230417530
The present invention relates to a wear sensor and a method for sensing wear occurring to an object. The present invention further relates to a wear sensing system comprising the wear sensor and a measuring device for measuring an amount of wear occurring to the object.
Plant and equipment in many industries are subject to wear by the passage or flow of abrasive materials. For example, in mining, ore may be passed through chutes onto conveyors for subsequent processing. These chutes are subject to substantial wear by the passage of large, heavy, and hard rocks. To extend the service life of such plant and equipment, it is known to fix sacrificial wear plates or wear liners to the surfaces which would otherwise be in contact with the abrasive material. Irrespective of whether or not wear plates are used, in order to optimally manage and maintain the plant and equipment, it is common practice to monitor for wear. This may be done by the use of wear sensors, in particular in situations in which manual inspection is physically impossible or requires substantial down time.
US 2012/043980 A1 describes a wear sensor having an electrical circuit comprising a plurality of discrete elements (resistors), wherein each of the discrete elements has a nominal electrical characteristic (e.g. the same resistance, or capacitance or inductance) and thus contributes to a measurable electrical characteristic of the circuit. Each discrete element is being capable of being electrically decoupled (i.e. disconnected) from the electrical circuit by action of wear on the sensor. As such, when wear occurs on the sensor and one or more of the discrete elements are electrically decoupled, a change in the measurable electrical characteristic of the entire electrical circuit occurs and the measured change indicates an amount of wear. However, measuring the overall electrical characteristic of the electrical circuit alone may not indicate a sensor fault, i.e. distinguish between a scenario when a resistor failure to contribute to the overall electrical characteristic is due to the resistor being worn away or due to another problem of the resistor.
WO 2020/061634 describes a wear sensor for use in a wear sensing fastener. A circuit is shown having resistors and Zener diodes for measuring wear. However, with the Zener diodes based design due to the nature of diodes, the voltage over the electrical circuit is proportional to the number of Zener diodes. This means that as the number of Zener diodes gets larger, the voltage highly increases. Thus, it is difficult to effectively generate the required voltage from a typical battery which may requires a step-up circuit. In other words, the use of Zener diodes in an electrical circuit of a wear sensor requires a higher voltage than a typical battery can provide and therefore would require step up convertor and constant current source. As a result, a Zener diodes based design limits the practical number of elements involved. For example, in a Zener diodes based design, a breakdown voltage of 1.8 V and 70 Zener diodes for the wear sensor requires a supply voltage of 1.8 V×70=126 V. This means that there is a practical upper limit. In addition, biasing the Zener diodes leads to increased current leading to a higher power consumption with negative effects on battery life.
To better indicate wear sensor fault, e.g. to better distinguish between a scenario when a resistor failure to contribute to the overall electrical characteristic is due to the resistor being worn away or due to another problem of the resistor, an electrical circuit as shown in
The electrical circuit 100 shown in
Such an electrical circuit for a wear sensor has, however, the following technical problems. A typical wear sensor would, for example, be equipped with 70 resistors which have to be individually probed in sequence. The overall measurement time is thus rather long (e.g. for a wear sensor with 70 resistors, the overall measurement time is about 0.6 seconds). The skilled person recognizes that a break in the common line irreversibly affects all measurements and the wear sensor becomes unusable as there is no redundancy. Further, the electrical circuit does not easily scale due to the number of required tracks (common line plus individual line tracks (e.g. 70) for each resistor) and adds complexity as one analogue to digital converter or the like is required per resistor. Typically, providing such an amount of analogue to digital converters for a sensor requires more than one programmable interface controller (PIC) or the like which increases the manufacturing costs and/or firmware requirements.
There is thus a need to address these technical problems associated with wear sensors having the above resistor-based design as shown in
The present invention is defined by the appended independent claims. Further preferred embodiments are defined by the dependent claims.
According to an aspect, a wear sensor comprises an electrical circuit comprising a sequence of discrete elements, each discrete element being capable to temporarily hold a digital data value, wherein the electrical circuit is configured to sequentially transfer or shift the digital data value from a first discrete element on a first side of the wear sensor to subsequent discrete elements toward a second side of the wear sensor. Each discrete element is capable of being electrically decoupled from the electrical circuit, sequentially in a direction from the second side by action of wear on the wear sensor, wherein a number of discrete elements in the sequence is reduced when wear occurs on the wear sensor.
According to another aspect, a method for sensing wear occurring to an object comprises sequentially transferring a digital data value from a first discrete element on a first edge of a wear sensor to subsequent discrete elements toward a second edge of the wear sensor. The wear sensor comprises an electrical circuit, the electrical circuit comprises a sequence of discrete elements, each discrete element temporarily holding the digital data value, and a discrete element is electrically decoupled from the sequence of discrete elements, sequentially in a direction from the second edge, by action of wear on the wear sensor, wherein a number of discrete elements in the sequence is reduced when wear occurs on the wear sensor.
According to another aspect, a wear sensing system comprises one or more wear sensors and a measuring device configured to measure an amount of wear occurring to an object based on the one or more wear sensors.
According to another aspect, equipment subject to wear comprises a wear sensor.
Embodiments of the present invention, which are presented for better understanding the inventive concepts and which are not to be seen as limiting the invention, will now be described with reference to the Figures in which:
The mechanism(s) described above and in more detail below solve technical problems that arise with regard to conventional wear sensors. It is desired to provide a wear sensor that is capable of accurately and steadily measuring wear occurring to an object, wherein measurement failures due to sensor outage should be avoided and the measurement time should be reduced. Furthermore, it is desired to provide an easily scalable wear sensor having small dimension.
Temporally holding a digital data value means to temporarily store the digital data value by a discrete element. Sequentially transferring or shifting the digital data value means to outputting a digital data value temporarily stored in a first discrete element and transmitting the outputted digital data value to a subsequent second discrete element which is connected to the first discrete element, wherein the second discrete element may then store the transmitted digital data value. The first edge 220 may indicate one end of the wear sensor 200 and the second edge 230 may indicate another end of the wear sensor 200.
Each discrete element 210, 211, 212, 213, and 214 may be capable of being electrically decoupled from the electrical circuit, sequentially in a direction from the second edge 230 by action of wear on the wear sensor 200, wherein a number of discrete elements in the sequence is reduced when wear occurs on the wear sensor 200. For example, each discrete element is capable of being electrically decoupled from the electrical circuit, sequentially in a direction from the second edge 230 towards the first edge 220 by action of wear on the wear sensor 200. When a discrete element is electrically decoupled from the electrical circuit, the discrete element may be disconnected from the sequence of discrete elements, thus reducing the number of discrete elements which exist in the sequence of discrete elements. This number may be 1, 2 (as shown in
In order to protect the wall of the chute 310, a plurality of wear liners or wear plates 312 (examples of equipment subject to wear) of thickness 315 may be installed onto the chute wall 311 which can be replaced or repaired more easily than the chute wall 311. These wear plates 312 may be of different size and can be replaced independently of each other depending on the amount of wear. However, it may be possible to also install only one wear plate 312 which is large enough to cover the whole chute wall 311. When wear occurs to the wear plate 312 due to the heavy and hard rocks 320 being passed through the cute 310, the thickness 315 of the wear plate 312 may be decreased.
Thus, in order to be able to accurately and continuously measure wear occurring to the wear plates 312 without having to stop the mining process, a wear sensor 340 may be installed in the wear plate 312. By means of the wear sensor 340, it is possible to accurately and continuously measure wear of the wear plate 312, i.e. measure the decrease of thickness of the wear plate 312 due to the rocks 320 passing through the chute 310. If no wear plates are used, the wear sensor 340 may be installed directly in the wall 311 of the chute 310.
The wear sensor 340 may be installed in a direction of the thickness of the wear plate 312 in such a way that the first edge 341 of the wear sensor 340 is directed outward of the chute 310 and the second edge 342 is directed inward of the chute 310. Thus, when the chute 310 is worn, in particular the wear plates 312, and the thickness 315 of the wear plates 312 decreases, at least one discrete element in the wear sensor 340 may be electrically decoupled from the electrical circuit of the wear sensor 340, sequentially in a direction from the second edge 342 towards the first edge 341 by action of wear on the wear plates 312 and thus also on the wear sensor 340. Thus, the number of discrete elements in the sequence of discrete elements of the wear sensor 340 may be reduced when wear occurs to the wear plates 312 and thus also on the wear sensor 340.
According to an embodiment, the reduced number of discrete elements in the wear sensor 340 may indicate an amount of wear. For example, the reduced number of discrete elements indicates the remaining thickness 315 of the wear plates 312. For example, as also shown in
In other words, the amount of wear may be obtained from the difference between the initial thickness 315 of the wear equipment before wear occurs (e.g. after the wear equipment has been installed) and the remaining thickness 315 after wear has occurred, wherein the thickness 315 may be reduced significantly when a large amount of wear has occurred. For example, the thickness 315 can be compared to a specific threshold and if the thickness 315 is below the specific threshold (meaning that the amount of wear is above the specific threshold), the mining process is stopped. Thus, during a phase where no rocks 320 pass through the chute, the wear plates 312 can be repaired or replaced. Thus, the wear occurring to the chute 310 can be measured continuously without having to stop the mining process during measurement, wherein the mining process only has to be stopped when the amount of wear is above a specific threshold and, for example, repair measures are necessary.
As explained above, the wear sensor may comprise discrete elements which temporally hold a digital data value and are able to transfer or shift the digital data value to a subsequent discrete element of the wear sensor. The wear sensor according to an embodiment of the present invention does not comprise a plurality of resistors as described with regard to
According to an embodiment, the electrical circuit of the wear sensor can be directly installed onto the object or equipment whose amount of wear should be measured. As described above, the object or equipment may be a wear plate or wear liner. According to another embodiment, the wear sensor may further comprise a substrate, wherein the electrical circuit may be supported by the substrate. The substrate may be disposed along a path subject to wear. For example, the substrate is a thin material of any suitable type, wherein the electrical circuit of the wear sensor is mounted onto the substrate. The substrate having the electrical circuit may then be placed on the object subject to wear. For example, with regard to
According to another embodiment, the discrete elements of the wear sensor may be placed or connected in series, i.e. consecutively, on the substrate, wherein the discrete elements of the wear sensor may be sequentially decoupled from the substrate as a wear progresses along the path. Again, the path is the direction of wear, for example a path along the thickness of a wear plate 312 as described with regard to
The discrete elements may be equally (or substantially equally) spaced in the electrical circuit or on the substrate. By equally (or substantially equally) spacing the discrete elements, the accuracy of the determination of the amount of wear occurring to an object or equipment can be improved and the calculation or measurement of the amount of wear can be facilitated. By increasing the number of discrete elements on a fixed length of the wear sensor, the accuracy may increase. When the number of discrete elements that were electrically decoupled from the electrical circuit by action of wear on the wear sensor is known, the number of decoupled discrete elements can be converted to a measure of length based on a preset distance or spacing between the discrete elements. For example, if three discrete elements were electrically decoupled and the discrete elements are equally spaced with a spacing of 1 mm, the number of three decoupled discrete elements can be converted to approximately 2 mm of wear or any other measure of length. Thus, once the amount of wear, for example represented by a measure of length, is above a threshold, repair or replacement measures can be performed with regard to the object subject to wear. It may be also possible to convert the amount of wear into a percentage measure, wherein repair or replacement should be performed when the amount of wear in percentage is above a threshold, for example, if more than 70% of a wear sensor (and thereby of a wear plate) is gone.
However, according to another embodiment, it is also possible that the discrete elements are not equally spaced in the electrical circuit or on the substrate. For example, the discrete elements may be spaced in an exponential or polynomial way. Even though the discrete elements are not equally spaced in the electrical circuit or on the substrate, the amount of wear can still be determined. For example, it is possible to arrange the discrete elements with smaller spacing in the direction of the first edge of the wear sensor and arrange the discrete elements with larger spacing in the direction of the second edge of the wear sensor; thus increasing the resolution and accuracy of wear detection in the direction of the first edge. In this case, a conversion from a number of discrete elements electrically decoupled from the electrical circuit to an amount of wear is based on a variance in spacing between the discrete elements.
According to an embodiment, the discrete elements may be flip-flop elements and the sequence of flip-flop elements may be a flip-flop array or shift register. A flip-flop element may have two stable states and can be used to store or hold state information or a digital data value, like 0 or 1 (represented by two different voltage values). A flip-flop element may be a device which stores or holds a single bit (binary digit) of data; one of its two states or bits represents a “1” and the other represents a “0”. The flip-flop element may be a clocked device, wherein such a clocked device may ignore its inputs except at the transition of a dedicated clock signal. The clock signal causes the flip-flop element either to change or to retain (hold) its output signal based upon the values of the input signals at the transition.
The electrical circuit 400 shown in
As shown in
When a sequence of flip-flop elements is provided, see also
The electrical circuit 400 may comprise a specific amount of tracks or lines, wherein the specific amount of tracks or lines is independent of the total number of discrete elements (flip-flop elements) included in the sequence. Thus, the dimension of the electrical circuit and the wear sensor can be minimized, as the number of tracks necessary for the electrical circuit does not increase when the number of discrete elements (flip-flop elements) is increased. Thus, the electrical circuit and the wear sensor can be easily scaled, i.e. the number of discrete elements may be easily changed without the need for further tracks, analog to digital converters or the like.
For example, as also shown in
According to an embodiment, the output Q of each flip-flop element 410 may be further connected to a diode 470, as shown in
Furthermore, the diode 470 may be configured in such a way that if the output signal (output Q) of the flip-flop element represents a digital data value of “0”, i.e. relates to a second amount of voltage of, for example, 0V to 0.4V, the diode 470 does not let current pass through to the track 450. For example, the diode 470 is a Si-diode (silicon diode) which does not let current pass at a voltage below 0.4 V.
A measuring device (not shown) may be connected to track 450 and may measure or detect a voltage value or current value at track 450. By measuring or detecting a voltage or current value at track 450, the measuring device can detect whether a digital value of “1” is still present in the sequence of flip-flop elements and can thus determine an amount of wear (as will be further explained below). In combination with the clock, the measuring device can further determine which flip-flop element currently outputs the digital data value of “1”. This is described in more detail below. By providing diodes 470, it is possible to provide more accurate wear measurements, as the diodes 470 only let current pass at high voltage while blocking at small erroneous voltages.
According to an embodiment, the amount of wear may be determined based on a number of clock transitions between the flip-flop elements in the sequence until the output over the sequence of flip-flop elements is a digital data value of zero (“0”), and preferably remains zero over a specific number of clocks. The output may have a digital data value of one (“1”) as long as a digital data value of one (“1”) is present in the sequence of flip-flop (and is therefore hold in the electric circuit).
In
For the next clock 2, the digital data value “1” is shifted from flip-flop element FF1 to flip-flop element FF2. Thus, at clock 2, the output Q of FF1 is “0” while the output Q of FF2 is “1”. For the remaining flip-flop elements FF3 to FF5, the output Q is also “0”. Thus, the output over the sequence of flip-flop elements FF1 to FF5 again amounts to the digital data value of “1” due to the digital data value “1” output by FF2. In this context, the diode D_FF2 lets current pass through to track 450 while the other diodes D_FF1 and D_FF3 to D_FF5 block.
The above procedure is also repeated for FF3, FF4, and FF5.
However, at clock 6 and all subsequent clocks, if any, the output over the sequence of flip-flop elements FF1 to FF5 now changes to “0”. This is due to the fact that the electrical circuit only comprises five flip-flop elements and flip-flop element FF5 shifts the digital data value of “1” out of the electrical circuit at clock 6.
The electrical circuit may only comprise five flip-flop elements or may have comprised more than five flip-flop elements during manufacturing, wherein the flip-flop elements after FF5 were electrically decoupled by action of wear on the wear sensor. As the digital data value of “1” at clock 6 and all subsequent clocks is no longer present in the sequence of flip-flop elements FF1 to FF5, the output over the sequence of flip-flop elements becomes zero. In other words, no current is transferred via the track 450 because all diodes D_FF1 to D_FF5 are blocking, i.e. are in a blocking state. If a measuring device is connected to the track 450, the measuring device may not be able to measure or detect any current transferred via track 450.
In order to now determine the amount of wear by, for example, a measuring device connected to track 450, the number of clock transitions may be counted until the output over the sequence of flip-flop elements FF1 to FF5 changes to zero (“0”), and preferably remains zero over a specific number of clocks. For example, if the specific number of clocks is one, the number of clock transitions is counted by using the detected current transferred by track 450 until the output of the sequence of flip-flop elements changes to zero in one clock. The counted number of clock transitions may then be compared to an expected number of clock transitions. If, however, the specific number of clocks is greater than one, the number of clock transitions is counted until the output of the sequence of flip-flop elements is zero over the specific number of subsequent clocks. For example, if the specific number of clocks is three, the number of clock transitions is counted until the output of the sequence of flip-flop elements is zero over three subsequent clocks. By observing a specific number of subsequent clocks and stopping the clock transition counting when the output of the sequence of flip-flop elements is zero over the specific number of clocks, a correct wear amount measurement is ensured even if errors with regard to the flip-flop elements occur. For example, if D_FF2 in
Thus, the wear sensor may also be configured to detect whether or not an error with regard to at least one flip-flop element of the sequence of flip-flop elements has occurred. For example, an error in a diode, as explained above, an error regarding signal transmissions via the tracks, or an error in the flip-flop element itself may occur. Furthermore, the wear sensor may not only detect whether or not an error has occurred but may also detect a position within the electrical current at which the error has occurred. For example, by regarding the output of the sequence of flip-flop elements in combination with the clock signal or clock transitions, it can be determined when the output of the sequence of flip-flop elements briefly changes to “0” and back to “1” and thus which flip-flop element may be affected by the error. By knowing the exact error position, the electrical circuit of the wear sensor can be easily repaired in a fast way.
For example, if during manufacturing 70 flip-flop elements are connected to form the wear sensor, the expected number of clock transitions is 70. Compared to a conventional resistor-based design (as shown in
In
As described above, the amount of wear may be determined by a measuring device or measuring unit connected to track 450. The measuring device and the electrical circuit may form the wear sensor, or the wear sensor may only comprise the electrical circuit, wherein the measuring device and the wear sensor comprising the electrical circuit form a wear sensing system.
However, it is also possible that a sensor comprising a transmitting unit is connected to track 450 which senses current transferred via track 450 and transmits data necessary for wear detection and measurement to an external device, i.e. to a device external to the wear sensor. The external device may then detect or measure the amount of wear. The external device is connected either wirelessly or with wire to the wear sensor.
As described above, as the amount of tracks is independent of the total number of flip-flop elements included in the sequence, the dimension of the electrical circuit and the wear sensor can be minimized. This is also advantageous for the design of printed circuit boards (PCB) as shown in
As in the wear sensor 810A of
However, by using a wear sensor 810B as shown in
According to another embodiment, the wear sensor as described above may further comprise at least one additional electrical circuit such that the wear sensor comprises two or more electrical circuits. The two or more electrical circuits may be independent of each other. The two or more electrical circuits may be connected in parallel, as also shown in
As the dimension of the electrical circuit can be minimized by the reduced number of tracks used in the electrical circuit, more than one electrical circuit can be included in the wear sensor, leading to redundancy. Thus, even when outage or problems in one electrical circuit occur, the wear sensor can still ensure proper and correct wear measurements due to the redundancy. Thus, failure rates with regard to wear sensors can be reduced.
In
The wear sensing system may either be implemented by a single device (see dashed lines) or may be implemented in a distributed way. If the wear sensing system is implemented in a distributed way, the wear sensor 1110 and the measuring device 1120 may be implemented as separate devices or units, wherein the wear sensor 1110 may transmit, to the measuring device 1120 either wirelessly or via a wire, all the data and information necessary for the measuring device to measure the amount of wear occurring to the object. In order to transmit the necessary data and information, the wear sensor 1110 may additionally comprise a transmitting unit (not shown), while the measuring device 1120 may comprise a receiving unit (not shown) to be able to receive the necessary data and information.
According to an embodiment, the measuring device 1120 may be a counter configured to count a number of clocks until an output of the one or more wear sensors is a digital data value of “0” over a specific number of clocks. For further details regarding the output of the wear sensor, in particular the output over the sequence of flip-flop elements, it is referred to
The wear sensor as described with
According to another embodiment, the wear sensor may be directly included in a housing, wall, bottom, or the like of a plant or equipment which is subject to wear. For example, the wear sensor is included directly in the wall of a chute used in the mining industry or any other equipment used in the mining industry that is subject to wear.
It will be apparent to those skilled in the art that various modifications and variations can be made in the entities and methods of this invention as well as in the construction of this invention without departing from the scope or spirit of the invention.
The invention has been described in relation to particular embodiments and examples which are intended in all aspects to be illustrative rather than restrictive. Those skilled in the art will appreciate that many different combinations of hardware, software and/or firmware will be suitable for practicing the present invention.
Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and the examples be considered as exemplary only. To this end, it is to be understood that inventive aspects lie in less than all features of a single foregoing disclosed implementation or configuration. Thus, the true scope and spirit of the invention is indicated by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20208640.1 | Nov 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/082704 | 11/23/2021 | WO |
