Sensor system for monitoring a powder handling device and a powder handling device comprising the same

Abstract

The present invention relates to a sensor system for monitoring a powder handling device. The sensor system includes an alternating electrical signal source electrically connectable to the powder handling device and a processing device. The processing device includes a measuring device and a controller communicatively connected to the measuring device. The controller is configured to receive measurement data from the measuring device and determine a phase difference between an input signal and an output signal based on the received measurement data.

Description

Technical Field

[0001] The present invention relates to a sensor system for monitoring a powder handling device. The sensor system comprises an alternating electric signal source electrically connectable to the powder handling device and a processing device. The processing device comprises a measuring device and a controller communicatively connected to the measuring device. Background Art

[0002] Modern powder handling machinery for chemical, pharmaceutical, dairy, or food industries is constantly required to process large quantities of powders, often by the ton. While the output demands placed on these machines are high, so too are the demands on quality and hygiene, as these powders are often destined for human consumption. Therefore, even a small amount of contamination, or even the suspicion that a batch has been contaminated, can cause production to stop and the processed batch to potentially be discarded. Furthermore, before the machinery can begin processing powder again, the source of the contamination must be identified and corrected, resulting in downtime and lost production.

[0003] One source of contamination is powder handling equipment. These devices are often made of stainless steel, which is inert to the powder being handled and easy to clean, thus meeting hygiene requirements. However, sometimes the surfaces of the powder handling equipment become scratched or otherwise damaged, which can cause metal debris to be mixed into the powder flow. An example of this is a rotary valve used to handle powders. A rotary valve consists of a rotor that rotates within a housing, and during normal operation, the rotor does not contact the housing. However, thermal expansion, bearing wear, incorrect assembly, tolerances, pressure from the cleaning fluid, or the powder being handled can all cause the rotor to contact and / or scratch the interior of the housing. Currently, sensor systems have been developed for monitoring powder handling equipment. A prior art sensor system is explained in more detail with reference to Figures 2a and 2b. However, these conventional sensor systems suffer from a low signal-to-noise ratio (SNR). A low SNR leads to a higher risk of false alarms. During cleaning, cleaning fluids can cause false alarms, necessitating the sensor system be shut down during cleaning. Even powder can cause false alarms in some cases. False alarms can become so troublesome that the sensor system is shut down by the operator, thereby jeopardizing the safety of the powder handling machinery that relies on the sensor system. To avoid these false positives, the collected data is sometimes filtered, however filtering the data runs the risk of filtering out contamination events from the data. In particular, the risk of brief contact between the rotor and the housing being filtered out, and therefore the risk of product contamination being overlooked. Summary of the Invention

[0004] It is an object of the present invention to overcome these problems and to provide a sensor system that overcomes or at least alleviates the problems of the prior art.

[0005] In a first aspect of the invention, this object and other objects are achieved using a sensor system for monitoring a powder handling device, wherein the sensor system includes: an alternating electrical signal source, which is electrically connectable to the powder handling device and is configured to generate an alternating electrical signal; a processing device, which includes a measuring device and a controller communicatively connected to the measuring device, wherein the measuring device is electrically connectable to the powder handling device and the alternating electrical signal source, wherein the measuring device is configured to collect measurement data about an input signal and an output signal, wherein the input signal is the alternating electrical signal before passing through the powder handling device, wherein the output signal is the alternating electrical signal after having passed through the powder handling device, wherein the controller is configured to receive the measurement data from the measuring device and determine a phase difference between the input signal and the output signal based on the received measurement data.

[0006] The phase difference between the input signal and the output signal depends on both the material (e.g., cleaning fluid or powder) within the powder handling device and the geometry of the powder handling device. Therefore, by determining the phase difference, a higher level of system information is obtained compared to conventional systems, resulting in a lower number of false alarms and a reduced or even eliminated requirement for filtering data. In addition, the sensor system according to the present invention is not limited to monitoring powder handling devices during operation. Since the phase difference provides information about the geometry of the powder handling device, newly manufactured powder handling devices can be measured as a quality check, for example, a baseline measurement of a quality-assured powder handling device can be determined, and this baseline measurement can be directly compared or used to establish a quality threshold to which measurements made on newly manufactured powder handling devices can be compared. Alternatively or in combination, the sensor system can also be applied to check used powder handling devices to see if they are still of sufficient quality for use. The determined phase difference can also be used for further processing, for example, for quantifying other parameters of the powder handling device, such as the electrical impedance of the powder handling device or the electrical reactance of the powder handling device. Impedance or reactance can provide further information about the geometry of the powder handling device and the material handled by the powder handling device.

[0007] In the context of this disclosure, the terms reactance and impedance are used interchangeably with the terms electrical reactance and electrical impedance, respectively.

[0008] A processing device is a device that includes any circuits and / or devices suitable for performing the functions described herein. The processing device may include a general-purpose or special-purpose programmable microprocessor, such as a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic array (PLA), a field-programmable gate array (FPGA), a dedicated electronic circuit, or a combination thereof. The processing device may, for example, be a computer or other special-purpose device suitable for performing the functions described herein. Preferably, the processing unit includes a receiver, a transmitter, and / or a transceiver for wired or wireless communication.

[0009] The measuring device can be any suitable device for measuring one or more characteristics of an electrical signal. The measuring device can measure one or more phase characteristics of the electrical signal. The measuring device can be a clock or an oscilloscope. The measurement data collected by the measuring device can be converted from analog format to digital format via an analog-to-digital converter. The digitally formatted measurement data can facilitate further processing of the data. Oscilloscopes and clocks can be standard components embedded in most printed circuit boards.

[0010] A controller is a device that includes any circuits and / or devices suitable for performing the functions described herein. The controller may include a general or special programmable microprocessor, such as a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic array (PLA), a field programmable gate array (FPGA), a dedicated electronic circuit, or the like, or a combination thereof. The controller may, for example, be a computer or other special purpose device suitable for performing the functions described herein. Preferably, the controller includes a receiver, a transmitter and / or a transceiver for wired or wireless communication. The controller may be configured to control the operation of the powder handling device, such as turning the powder handling device on and off. Alternatively or in combination, the controller may be configured to transmit a signal with information about the powder handling device to a central system, wherein an operator can peruse the information about the powder handling device and, depending on the information received, the operator can change the operating settings of the powder handling device.

[0011] The measuring device may be configured to transmit the measurement data to the controller wirelessly and / or via a wired connection.In some embodiments, the measuring device and the controller are integrated into one unit.

[0012] The alternating electric signal generated by the alternating electric signal source may be a simple harmonic alternating current signal, or alternatively, a square wave signal, a triangle signal, a step signal, or the like.

[0013] In the context of this disclosure, phase difference should be interpreted broadly. Thus, phase difference can be any phase difference between an input signal and an output signal. Thus, phase difference can be expressed as a phase angle or a time delay.

[0014] In an embodiment, the sensor system comprises a conditioning device, preferably a resistor having a predefined resistance, which is electrically connectable to the powder handling device and the alternating electrical signal source, wherein the output signal is the alternating electrical signal after having passed through both the powder handling device and the resistor.

[0015] The conditioning device can be integrated into the processing device along with the controller and the measuring device. Alternatively, the conditioning device can be an additional component external to the processing device. The conditioning device can be used as a signal conditioner, thereby providing the freedom to modify the output signal by a known amount, for example, to improve the signal-to-noise ratio (SNR). Although resistors are specifically mentioned, other signal conditioners such as amplifiers, bridges, comparators, or voltage followers can also be implemented.

[0016] In an embodiment, the adjustment means is modifiable.

[0017] Being able to modify the adjustment device allows for modification of the measurement range and optimization of sensitivity without having to remove or add additional adjustment devices. Furthermore, the adjustment device can be modified while the powder handling apparatus is in operation, allowing for rapid adaptation of the sensor system. In embodiments where the adjustment device is a resistor, the resistor can have a modifiable resistance, allowing the resistance of the resistor to be varied.

[0018] The regulating device may be modified via user input provided directly to the regulating device or via a device operably connected to the regulating device, such as a controller or central hub configured to control the operation of the powder handling device.

[0019] In an embodiment, the controller is operatively connected to the regulating device, and the controller is configured to modify the regulating device based on a comparison between the determined phase difference and a first threshold value.

[0020] Thus, a feedback loop is established between the regulating device and the controller. This feedback loop can help ensure that useful data is obtained without requiring user intervention. Thus, the sensor system achieves a higher level of autonomy. For example, if the regulating device is a resistor with a modifiable resistance, the controller can be configured to modify the resistance of the resistor in response to a comparison between the determined phase difference and a first threshold value.

[0021] The comparison may be to see whether the determined phase difference exceeds or does not exceed a first threshold value.

[0022] The first threshold value can be the lower limit, upper limit or range of the phase difference. In some embodiments, the determined phase difference can be further used to determine reactance and / or impedance. In such embodiments, the first threshold value can be the lower limit, upper limit or range of impedance and / or reactance. The first threshold value can be determined based on baseline measurements. These baseline measurements can be measurements performed in a controlled environment or during the startup of the powder disposal device. By modifying the regulating device, the phase difference can be amplified or otherwise changed to adapt to the operating conditions so as to give an optimized signal that allows the controller to determine the phase difference. In some embodiments, if the material to be processed by the powder disposal device changes (for example, a new powder with different intrinsic properties) or if a cleaning liquid is to be introduced into the powder disposal device, the controller can be configured to modify the regulating device. This can be particularly advantageous for optimizing the sensitivity of the sensor system. In some embodiments, the controller is configured to modify the regulating device based on a comparison between the determined phase difference and multiple first threshold values. The multiple first threshold values ​​can be used to define different measurement ranges. Different ranges may involve different sensitivities, thereby allowing greater flexibility in modifying the regulating device.

[0023] In an embodiment, the controller is further configured to determine a condition of the powder handling device and / or a condition of powder handled by the powder handling device based on the phase difference.

[0024] The condition of the powder handling device may be whether the powder handling device is in a normal operating state (e.g., there is no scratching or irregular contact between the parts of the powder handling device). The condition of the powder handling device may also relate to the wear state of the powder handling device, such as whether it is time to maintain or replace the powder handling device or its parts. In the case of a rotary valve, the condition may relate to whether the rotor contacts the housing of the rotary valve. The condition of the powder handled by the powder handling device may relate to the moisture content of the powder, the size of the powder particles, the protein content, the sugar content, the fat content, the powder temperature, or the powder flow rate. The determination of the condition of the powder handling device and / or the powder handled by the powder handling device can be performed by observing whether the determined phase difference deviates by more than one, two, or three standard deviations compared to a plurality of previously determined phase differences. The determination of the condition of the powder handling device and / or the powder handled by the powder handling device can be performed by having one or more measurement ranges associated with different characteristics of the powder handling device and / or the powder handled by the powder handling device. The controller may be provided with a data storage device for storing one or more reference and / or baseline measurements. The determination of the condition of the powder handling device and / or the powder handled by the powder handling device can be performed by comparing the determined phase difference and / or the determined impedance and / or reactance with one or more reference and / or baseline measurements. These reference and / or baseline measurements can be one or more determined phase differences or impedances related to the condition of the powder handling device and / or the powder handled by the powder handling device, such as reference measurements related to the situation when a cleaning liquid is introduced into the powder handling device, reference measurements related to scraping of the powder handling device, reference measurements related to different moisture contents of the powder being handled by the powder handling device, etc.

[0025] In an embodiment, the controller is further configured to compare the phase difference with a second threshold value and output an operation signal based on the comparison.

[0026] The operating signal may be a stop signal. By outputting a stop signal, quick preventive measures may be taken to limit the negative effects caused by unwanted events (e.g., scratching or irregular operation of the powder handling device). The operating signal may also be a signal output to control other parameters of the powder handling device (e.g., power consumption or one or more speed settings of the powder handling device). The operating signal may be output to one or more devices, for example, the operating signal may be output to devices around the powder handling device. The operating signal may be output and stored in a database and used for further processing. If the operating signal is stored in a database, it may be used for machine learning and / or developing a training data set for a controller of the powder handling device and / or other controllers of other powder handling devices.

[0027] The comparison may be to see whether the determined phase difference exceeds or does not exceed a second threshold value.

[0028] The second threshold value can be a lower limit, an upper limit or a range of the phase difference. In some embodiments, the determined phase difference can be further used to determine reactance and / or impedance, in which case the second threshold value can be a lower limit, an upper limit or a range of impedance and / or reactance. The second threshold value can be determined based on a reference measurement or a baseline measurement. These baseline measurements can be measurements performed in a controlled environment or during the startup of the powder disposal device. The output operation signal can be received by an alarm device that can generate an alarm (e.g., a high sound and / or a flashing light). The operation signal can be output to a device that can control the operation of the powder disposal device, which can then stop the operation of the powder disposal device or change the process parameters of the powder disposal device when receiving the operation signal. The controller can also output the operation signal directly to the powder disposal device.

[0029] In an embodiment, the controller is configured to determine an amplitude change between the input signal and the output signal based on the received measurement data.

[0030] The amplitude variation between the input signal and the output signal can provide additional information about the state of the powder handling device and / or the material handled by the powder handling device. The amplitude variation can provide information about the resistance of the powder handling device. The determined amplitude variation can be further processed to determine the impedance of the powder handling device. The determined amplitude variation can be used to determine the condition of the powder handling device and / or the powder handled by the powder handling device. The amplitude variation can be used together with the determined phase difference to determine the condition of the powder handling device and / or the powder handled by the powder handling device.

[0031] In an embodiment, the controller is further configured to determine whether the amplitude change has exceeded a third threshold, and output an operation signal if the amplitude change exceeds the threshold.

[0032] The third threshold value can be a lower limit, upper limit, or range of the amplitude variation. In some embodiments, the determined amplitude variation can be further used to determine reactance and / or impedance. In such embodiments, the third threshold value can be a lower limit, upper limit, or range of impedance and / or reactance. The third threshold value can be determined based on a reference measurement or a baseline measurement. These baseline measurements can be measurements performed in a controlled environment or during startup of the powder handling device.

[0033] In an embodiment, the alternating electric signal source generates the alternating current signal with a predefined frequency and amplitude, and wherein the predefined frequency and amplitude are modifiable by the alternating electric signal source.

[0034] Making the alternating electrical signal modifiable allows for a greater degree of freedom, allowing the generated alternating electrical signal to be tailored to the current situation. In certain embodiments, it is also contemplated that the controller forms a feedback loop with the alternating electrical signal source, thereby allowing the controller to modify the generated alternating electrical signal to optimize the collected measurement data. In some embodiments, the controller is operatively connected to both the alternating electrical signal source and the modifiable resistor, thereby enabling the controller to modify both the generated signal and the signal conditioning.

[0035] In an embodiment, the powder handling device is a rotary valve comprising a rotor and a housing, wherein the rotor comprises a rotor shaft defining an axial direction and a radial direction, the rotor further comprising a plurality of blades connected to the rotor shaft and extending radially from the rotor shaft, wherein the rotor shaft and the plurality of blades are configured to rotate within the housing around a rotation axis parallel to the axial direction without contacting the housing.

[0036] Although the sensor system can be suitable for use with rotary valves, the sensor system is not limited to rotary valves. The sensor system can be used with screw conveyors, simple pipe segments, agitators, mills (mils) or any other powder handling equipment. In some embodiments, the sensor system can also be used in conjunction with non-conductive powder handling equipment (e.g., polycarbonate tubes). In such embodiments, the sensor system can be provided with conductive plates that can be mounted on the exterior of the non-conductive powder handling equipment. These conductive plates are then electrically connected to the sensor system. Thus, the conductive plates and the non-conductive powder handling equipment can be modeled as capacitors. Thus, the sensor system is allowed to measure the phase difference on the non-conductive powder handling equipment in a non-destructive or non-invasive manner relative to the powder and / or the powder handling equipment.

[0037] In a second aspect of the invention, there is provided a powder handling device comprising a sensor system according to the first aspect of the invention.

[0038] In an embodiment, the powder handling device is a rotary valve comprising a rotor and a housing, wherein the rotor comprises a rotor shaft defining an axial direction and a radial direction, the rotor further comprising a plurality of blades connected to the rotor shaft and extending radially from the rotor shaft, wherein the rotor shaft and the plurality of blades are configured to rotate within the housing around a rotation axis parallel to the axial direction without contacting the housing, wherein the alternating electrical signal source is electrically connected to the rotor and the housing, and wherein the measuring device is electrically connected to the rotor and the housing.

[0039] In an embodiment, the rotor shaft is rotatably mounted to the housing by means of insulating bearings or insulating sleeves.

[0040] In a third aspect of the present invention, a method for monitoring a powder handling device is provided, the method comprising the following steps: providing a powder handling device according to the second aspect of the present invention; generating the alternating electric signal by the alternating electric signal source; collecting measurement data about the input signal and the output signal by the measuring device; and determining the phase difference between the input signal and the output signal by the controller.

[0041] In an embodiment, the steps of the method are performed during operation of the powder handling apparatus.

[0042] It should be noted that the present invention relates to all possible combinations of features recited in the claims. Other objects, features, and advantages of the inventive concept will become apparent from the following detailed disclosure, the appended claims, and the accompanying drawings. Features described with respect to one aspect may also be combined with other aspects, and the advantages of that feature apply to all aspects in which that feature is combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the following description, embodiments of the present invention will be described with reference to the accompanying drawings, in which:

[0044] Figure 1a and Figure 1b are schematic cross-sectional views of two different powder handling devices, more specifically rotary valves;

[0045] 2a and 2b are schematic cross-sectional views of a powder handling device having a prior art sensor system in two different states;

[0046] Figure 3 is a block diagram of a powder handling device including a sensor system according to an embodiment of the present invention;

[0047] Figure 4 is a graph showing the relationship between the amplitude of the alternating electrical input signal and the alternating electrical output signal and time;

[0048] Figure 5 is a block diagram of a method according to an embodiment of the present invention; and

[0049] Figure 6 The present invention is a circuit diagram of a rotary valve electrically connected to an alternating electric signal source and a regulating device. DETAILED DESCRIPTION

[0050] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. However, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness.

[0051] Initial reference Figure 1a and Figure 1b , shows two different rotary valves 1. Both rotary valves 1 include a housing 11. The housing 11 is made of stainless steel, but other suitable materials are contemplated. An inlet 12 is formed in a section of the housing 11, which is used to admit a flow of powder into the interior of the housing 11. As shown, the inlet 12 can take the form of a funnel 12. The inlet 12 can also be an opening in the housing 11 connected to a hopper or the like. In this embodiment, the inlet 12 is formed in the top section of the housing 11, allowing powder to fall into the housing 11. A rotor is positioned within the housing 11. The rotor includes a rotor shaft 13 defining an axial direction and a radial direction. The rotor further includes a plurality of blades 15 connected to and extending radially from the rotor shaft 13. The rotor shaft 13 and the plurality of blades 15 are configured to rotate within the housing 11 about a rotation axis R parallel to the axial direction without contacting the housing 11. The blades 15 are typically arranged so that a gap is formed between the housing 11 and the blades 15, preferably small enough to obstruct the passage of powder. The blades 15 define a compartment for receiving powder from the inlet 12. The blades 15 and the rotor shaft 13 are arranged to rotate at a sufficiently low speed to ensure that no sparks are generated if the blades 15 contact the housing 11. The rotor is here connected to the housing via an insulating connection 14. The insulating connection 14 may be an insulating bearing or an insulating sleeve. In the embodiment shown, the rotor shaft 13 is connected to the housing 11 via the insulating connection 14. An outlet 16 is formed in a section of the housing 11. In the embodiment shown, the outlet 16 is formed in a bottom section of the housing 11, thereby allowing powder to leave the housing by falling through the housing 11. In Figure 1a In the rotary valve shown in FIG, the outlet 16 is formed directly opposite the inlet 11, wherein both the inlet 11 and the outlet 16 allow powder to pass in a direction perpendicular to the rotation axis R. However, Figure 1b A different embodiment is shown in which the outlet 16 is not formed directly opposite the inlet 11. Figure 1b In the embodiment of the present invention, the inlet 11 allows powder to pass in a direction perpendicular to the rotation axis R, and the outlet 16 allows powder to pass in a direction parallel to the rotation axis R. In addition, an additional inlet 17 is formed in the housing 11. The additional inlet 17 allows an air flow to be introduced into the housing. The air flow is intended to be used to blow the powder into the outlet 16.

[0052] Referring to Figures 2a and 2b, schematic cross-sectional views of a powder handling device 1 equipped with a prior art sensor system 2' are shown in two different states. In the first state, shown in Figure 2a, the powder handling device is in normal operation. In the first state, the prior art sensor system 2' also provides direct current through the rotor and housing 11 of the powder handling device 1 in addition to resistor R. In the second state, shown in Figure 2b, the powder handling device 1 is in an abnormal state in which the rotor blades 15 contact the housing 11. In the second state, the prior art sensor system 2' provides direct current through the rotor and housing 11 of the powder handling device 1. However, resistor R is short-circuited due to the contact between the blades 15 and the housing 11. Therefore, by monitoring the direct current in the prior art sensor system 2', it is possible to determine whether resistor R is short-circuited. However, the supplied direct current has a small value to avoid electrifying any components, which in turn may cause sparks, which can be catastrophic when handling powder. The small value of the direct current results in a low signal-to-noise ratio (SNR), which can cause false alarms or true alarms to be filtered out.

[0053] refer to Figure 3 , shows a schematic block diagram of a powder handling device 1 equipped with a sensor system 2 according to an embodiment of the present invention. The sensor system 2 includes an alternating electric signal source 21. The alternating electric signal source 21 is electrically connected to the powder handling device 1 and is configured to generate an alternating electric signal. The electric signal source 21 is configured to generate an alternating electric signal having a predefined frequency and amplitude. Preferably, the predefined frequency and amplitude can be modified by the alternating electric signal source, thereby allowing the alternating electric signal source to send out a variety of alternating electric signals. The measuring device 22 is electrically connected to the powder handling device 1 and the alternating electric signal source 21.

[0054] The measuring device 22 is included in the processing device 24. The measuring device 22 is configured to collect measurement data about an input signal 25 and an output signal 26. The input signal 25 is an alternating electrical signal before passing through the powder handling device 1. The output signal 26 is an alternating electrical signal after having passed through the powder handling device 1.

[0055] The processing device 24 further includes a controller 23 communicatively connected to the measuring device 22. The controller 23 is configured to receive measurement data from the measuring device 22 and determine the phase difference Δt between the input signal 25 and the output signal 26 based on the received measurement data. The sensor system 2 further includes a conditioning device 27 for conditioning the input signal 25 and / or the output signal 26. In the embodiment shown, the conditioning device 27 is a resistor 27 electrically connected to the powder handling device 1 and the alternating electrical signal source 21. However, in other embodiments, the conditioning device 27 can be one or more of the following: a filter, an operational amplifier, a resistor, a signal converter, an attenuator, a comparator, a voltage follower, or a surge protector. In some embodiments, the output signal 26 is an alternating electrical signal after having passed through both the powder handling device 1 and the resistor 27. In some embodiments, the input signal 25 is an alternating electrical signal before passing through the powder handling device 1 and after having passed through the conditioning device 27. The input signal 25 and the output signal 26 can pass through the same conditioning device 27 or different conditioning devices. The output signal 26 can have a first set of conditioning devices associated with it. Input signal 26 may have a second set of conditioning devices associated therewith. The first set of conditioning devices and the second set of conditioning devices may be the same set of conditioning devices or different sets of conditioning devices. Resistor 27 has a predefined resistance. The predefined resistance of resistor 27 is a modifiable resistance. Controller 23 is operatively connected to resistor 27, i.e., the controller can control the operation of resistor 27. Controller 23 is configured to modify the resistance of resistor 27 based on a comparison between the determined phase difference Δt and a first threshold value.

[0056] In some embodiments, the regulating device 27 may be included in the processing device 24. In other embodiments, the regulating device 27 may be provided as a unit separate from the processing device 24. The controller 23 is operably connected to the alternating electric signal source 21, that is, the controller can control the operation of the alternating electric signal source 21. Therefore, the controller can control the frequency and / or amplitude of the electric signal generated by the alternating electric signal source 21. The controller 23 can be configured to control the operation of the alternating electric signal source 21 in response to a determined phase difference exceeding a threshold. The controller 23 can be configured to determine the condition of the powder handling device 1 and / or the condition of the powder handled by the powder handling device 1 based on the phase difference Δt. The controller 23 can be configured to compare the phase difference with a second threshold and output an operation signal based on the comparison. The controller 23 can be configured to determine the amplitude change between the input signal and the output signal based on the received measurement data. The controller 23 can be further configured to compare the amplitude change with a third threshold and output an operation signal based on the comparison.

[0057] In the embodiment shown, the controller 23 is communicatively connected to the external sensor 5. In the embodiment shown, the external sensor 5 is configured to collect measurement data about the powder handling device 1. The measurement data collected by the external sensor 5 may be about the temperature or power consumption of the powder handling device 1. The data collected by the external sensor 5 may be associated with the measurement data collected by the measuring device 22 to achieve a more accurate sensor system 2. The external sensor 5 may alternatively be configured to collect data about the environment in which the powder handling device 1 is placed. The environmental data may be air temperature or air moisture content. The external sensor may be one or more of the following: an accelerometer, a thermal sensor, an encoder, a tachometer, a microphone, a strain gauge, a current measurement sensor, or a torque sensor. The external sensor 5 is also communicatively connected to the external device 3.

[0058] In the illustrated embodiment, the controller 23 is communicatively connected to the external device 3. The external device 3 may be an alarm device capable of outputting an alarm in response to receiving a stop signal from the controller 23. The external device 3 may be a central hub for controlling the operation of the mechanical device or at least a portion of the mechanical device, so that if the controller 23 outputs an operation signal, the central hub can receive the operation signal and, in turn, stop or change the operation of the powder handling device 1 and, if necessary, other surrounding devices in the mechanical device. The external device 3 may be a display for displaying the determined phase difference and / or other collected measurement data.

[0059] refer to Figure 4 , the graph shows the amplitude versus time of an alternating electrical input signal 25 and an alternating electrical output signal 26. The two alternating electrical signals 25 and 26 have the same frequency. However, because the output signal 26 has passed through the powder handling apparatus 1 and possibly the signal conditioning device 27, a phase difference Δt and an amplitude difference ΔA exist between the input signal 25 and the output signal 26. The phase difference Δt and the amplitude difference ΔA depend on the powder handling apparatus 1, the material being processed by the powder handling apparatus 1, and possibly the signal conditioning device 27.

[0060] refer to Figure 5, shows a block diagram of method 4 according to an embodiment of the present invention. Method 4 includes four steps. In a first step 41, a powder handling device 1 having a sensor system 2 according to an embodiment of the present invention is provided. In a second step 42, an alternating electrical signal is generated by an alternating electrical signal source 21. In a third step 43, measurement data regarding the input signal and the output signal are collected by a measuring device 22. In a fourth step 44, a phase difference Δt between the input signal 25 and the output signal 26 is determined by a controller 23. The steps of method 4 can be performed during operation of the provided powder handling device 1, thereby allowing real-time monitoring of the powder handling device 1. In some embodiments, the method further includes a sixth step 46, in which the measurement data is further processed. The further processing of the measurement data can be for determining the impedance or reactance of the system. The further processing of the measurement data can be for using the data in a neural network or for machine learning purposes. The further processing of the measurement data can be for generating operating signals for the powder handling device or other surrounding devices based on the measurement data. The further processing of the measurement data can be for determining the condition of the powder handling device and / or the powder handled by the powder handling device. In some embodiments, the steps of the method are repeated over a period of time (e.g., days, weeks, months, or years), thereby allowing measurement data to be collected over a period of time, thus allowing an operator or a dedicated processing unit to analyze temporal changes with respect to the powder handling device 1 or the powder handled by the powder handling device 1. In some embodiments, the steps of method 4 are performed on a newly manufactured powder handling device, thus allowing a check on whether the newly manufactured powder handling device is of sufficient quality.

[0061] refer to Figure 6 , shows a circuit diagram of an embodiment of a powder handling device, generally designated 1. In the following the powder handling device will be referred to as a rotary valve 1, but the invention is equally applicable to other powder handling devices. A rotary valve 1 is shown electrically connected to an alternating electrical signal source 21 and a regulating device 27. The regulating device 27 in the circuit diagram is a resistor 27 having a modifiable resistance. The circuit is shown as having a ground 28. The sensor system may also include a ground 28. The ground 28 provides a fixed reference point for the input signal 25 and the output signal 26. The ground 28 may also help to ensure that charge does not accumulate in the powder handling device 1, thereby reducing the risk of sparks due to charge accumulation. It has been found from experimental data that the rotary valve 1 can be modeled in the circuit roughly as a resistor connected in parallel with a capacitor. Figure 6 The total impedance of the circuit shown in can be expressed as

[0062] Z tot =Z Rm +Z RV

[0063] Among them, Z Rmis the impedance of resistor 27, and Z RV is the impedance of rotary valve 1. Since we know Z Rm is given by resistor 27, and Z RV can be modeled as a resistor connected in parallel with a capacitor, where the reactance of the capacitor can be expressed as

[0064]

[0065] Among them, C RV is the capacitance of the rotary valve 1 , and ω is the angular frequency of the alternating electric signal generated by the alternating electric signal source 21 .

[0066] The total impedance can then be expressed as

[0067]

[0068] Among them, R M is the modifiable resistance of resistor 27, and R RV is the resistance of rotary valve 1. R M and ω are known values ​​and can be modified in some cases if necessary. Assuming that the capacitance of the rotary valve 1 can be modeled as a plate capacitor represented by the blade 15 and the housing 11 of the rotary valve 1, then R RV and C RV It can be expressed as

[0069]

[0070] Where ∈ is the dielectric constant of the material between the blade 15 and the housing 11, A is the cross-sectional area between the blade 15 and the housing, d is the distance between the blade 15 and the housing 11, ρ is the material resistivity of the rotary valve 1, and l is the length that the current travels through the rotary valve 1. Therefore, the total impedance Z TOT depends on the geometry of the rotary valve 1 and the material inside the rotary valve 1. In addition, the phase angle produced by the total impedance can be expressed as

[0071]

[0072] Therefore, by determining the phase angle of the alternating electrical signal passing through the rotary valve 1 and the resistor 27, information about the material inside the rotary valve and the geometry of the rotary valve 1 is obtained. Although the above electrical model and explanation are described with reference to a rotary valve, the same analysis can be performed on other powder handling devices with necessary modifications. Such an analysis can further take into account inductive effects. The determined phase angle can also be used to quantify the impedance of the rotary valve 1. The quantified impedance can then provide further information about the geometry of the powder handling device and the material being processed by the powder handling device. In addition, the phase angle resulting from the total impedance can be modified by adjusting the adjustable resistance of the resistor 27, for example, thereby allowing the signal to be enhanced by modifying the measurement range and optimizing the sensitivity.

[0073] Furthermore, variations of the disclosed embodiments are understood and effected by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A sensor system for monitoring a powder handling device, wherein: The sensor system includes: an alternating electrical signal source electrically connectable to the powder handling device and configured to generate an alternating electrical signal, a processing device comprising a measuring device and a controller communicatively connected to the measuring device, wherein the measuring device is electrically connectable to the powder handling device and the alternating electrical signal source, wherein the measuring device is configured to collect measurement data regarding an input signal and an output signal, wherein the input signal is the alternating electrical signal before passing through the powder handling device, wherein the output signal is the alternating electrical signal after having passed through the powder handling device, wherein the controller is configured to receive the measurement data from the measuring device and determine a phase difference between the input signal and the output signal based on the received measurement data, Wherein, the controller is further configured to determine a condition of the powder handling device based on the phase difference.

2. The sensor system according to claim 1, further comprising a regulating device electrically connectable to the powder handling device and the alternating electrical signal source, wherein The output signal is an alternating electrical signal after having passed through both the powder handling apparatus and the conditioning device.

3. The sensor system according to claim 2, wherein: The adjustment device is modifiable.

4. The sensor system according to claim 3, wherein: The controller is operatively connected to the regulating device, and wherein the controller is configured to modify the regulating device based on a comparison between the determined phase difference and a first threshold value.

5. The sensor system according to any one of the preceding claims, wherein The controller is further configured to: The phase difference is compared with a second threshold, and An operation signal is output based on the comparison.

6. The sensor system according to any one of claims 1 to 4, wherein: The controller is configured to determine an amplitude change between the input signal and the output signal based on the received measurement data.

7. The sensor system according to claim 6, wherein: The controller is further configured to: comparing the amplitude change to a third threshold, and An operation signal is output based on the comparison.

8. The sensor system according to any one of claims 1 to 4, wherein: The alternating electrical signal source generates an alternating electrical signal having a predefined frequency and amplitude, and wherein the predefined frequency and amplitude are modifiable by the alternating electrical signal source.

9. The sensor system according to any one of claims 1 to 4, wherein: The powder handling device is a rotary valve including a rotor and a housing, wherein the rotor includes a rotor shaft defining an axial direction and a radial direction, and the rotor further includes a plurality of blades connected to the rotor shaft and extending radially from the rotor shaft, wherein the rotor shaft and the plurality of blades are configured to rotate within the housing around a rotation axis parallel to the axial direction without contacting the housing.

10. The sensor system according to claim 2, wherein: The adjusting device is a resistor having a predefined resistance.

11. A powder handling device comprising the sensor system according to any one of claims 1 to 10.

12. The powder handling apparatus according to claim 11, wherein: The powder handling device is a rotary valve including a rotor and a housing, wherein the rotor includes a rotor shaft defining an axial direction and a radial direction, the rotor further including a plurality of blades connected to the rotor shaft and extending radially from the rotor shaft, wherein the rotor shaft and the plurality of blades are configured to rotate within the housing around a rotation axis parallel to the axial direction without contacting the housing, wherein the alternating electric signal source is electrically connected to the rotor and the housing, and Wherein, the measuring device is electrically connected to the rotor and the housing.

13. The powder handling apparatus according to claim 12, wherein: The rotor shaft is rotatably mounted to the housing via insulating bearings or insulating sleeves.

14. A method for monitoring a powder handling device, wherein: The method comprises the following steps: There is provided a powder handling apparatus according to any one of claims 11 to 13, The alternating electric signal is generated by the alternating electric signal source, collecting measurement data about the input signal and the output signal by the measurement device, and The controller determines a phase difference between the input signal and the output signal.

15. The method according to claim 14, wherein The steps of the method are performed during operation of the powder handling apparatus.

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