DE102018108601A1 - Device for detecting foreign bodies in a substrate stream - Google Patents

Abstract

The invention relates to a device (1) for detecting a foreign body (2, 3) in a measuring volume (4) in a transported substrate stream of a foodstuff or animal feed, wherein the measuring volume (4) comprises a flow body (5) in the form of a cylindrical tube (5). 6) is, by means of a sensor device (7) with at least one sensor element (8.1) with at least two electrodes (9.1,9.2). In order to provide a detection device and a detection method with which solid fragments in the form of electrically conductive and electrically non-conductive solids can be detected during the processing of the food or feed products to a final product and optionally excluded from the processing process, the invention proposes the sensor element (8.1) detects the foreign body (2, 3) by means of impedance measurement.

Description

The invention relates to a device for detecting a foreign body in a measuring volume in a transported substrate stream of a food or a feed according to the preamble of claim 1, a system comprising the device according to the invention according to claim 6 and a method for detecting a foreign body in a transported stream of a food or a feed according to the preamble of claim 9.

In the food and feed industry, a wide range of products is processed, which are delivered by suppliers packed in containers to food or feed manufacturers. In most cases, these products are frozen and must be unpacked and thawed at the manufacturer. The unpacking of the products can be done manually or fully automatically, whereas the thawing process is fully automatic during the processing process. Already at the supplier packaging material, such as plastic film residues, wood, glass or cable ties or metallic foreign bodies such as staples or binding wire, collectively referred to as solid fragments, get into the products. In particular, when freezing meat products, solid fragments can be undesirably frozen into the meat products or, for example in the form of a foil, they can inadvertently stick to the frozen meat products as they are unpacked and be conducted into the thawing process.

In the food and feed industry, however, there is a need to exclude unwanted solids fragments generally from the processed food or feed so that they do not reach the end customer. Therefore, the solids fragments should already be detected in the processing process and removed from the food or feed before it is repackaged, for example, canned or gedetütet.

From the DE19981337717 Detection system for detecting foreign bodies in a continuous flow of goods, such as bulk or piece goods, in particular granular or powdery food, with a detection device for detecting the foreign bodies in the flow of goods known, wherein the foreign bodies are metallic foreign body.

The DE200620002507 relates to detectable plastic protective gloves for the food processing and pharmaceutical industries, which contain as filler a highly magnetic mineral, so that the so prepared gloves can be detected by metal detectors during the manufacturing process.

A disadvantage of the known detection devices and systems is that they are only suitable for the detection of metallic or prepared with metallic materials foreign bodies or solid fragments. However, a detection of, for example, plastic, glass or wood fragments or other electrically non-conductive solids fragments or foreign bodies in the continuous flow of goods in the processing of food or feed products is not possible with the known detection devices and systems.

It is therefore an object of the present invention to provide a detection device and a detection method, which detects solid fragments in the form of electrically conductive and electrically non-conductive solids in the processing of food or feed products to a final product and optionally excluded from the processing process can be.

The above object is achieved by a device having the features of claim 1, by a system having the features of claim 6 and by a method having the features of claim 9. Further advantages, features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the device according to the invention, of course, also in connection with the inventive system comprising the device according to the invention, and also in connection with the method for detecting a foreign body in a transported stream of a food or feed and vice versa, so that with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or can be.

The device according to the invention for detecting a foreign body in a measuring volume in a transported substrate stream of a food or animal feed, wherein the measuring volume is a flow body in the form of a cylindrical tube, by means of a sensor device with at least one sensor element with at least two electrodes, includes the technical teaching, the sensor element detects the foreign body by means of impedance measurement.

A cylindrical tube in the sense of the present invention may be a pipe with a standard nominal diameter of 65 or 80 cm in order to be in a processing plant with standard nominal width of 65 or 80 cm can be integrated or retrofitted into it. Of course, the cylindrical tube may also have a different nominal diameter, but advantageously the nominal diameter of the tube is adapted to the nominal size of the processing plant, so that in the course of the cylindrical tube of the device according to the invention, the flow rate remains the same and for a tube with a smaller diameter than for The processing plant does not come to a backwater in the substrate promotion in the processing process.

According to the present invention, foreign bodies are detected in a transported stream of a food or a feed by means of a sensor device in a flow body designed as a cylindrical tube, wherein the sensor device comprises at least one sensor element with at least one pair of electrodes. According to the invention, the sensor element measures the impedance of the food or feed flowing through the flow body, whereby when passing through a foreign body in the food or feed stream through the flow body, the sensor element registers a change in the impedance and thereby detects the foreign body. Advantageously, the measurement is carried out simultaneously on the basis of two sensor elements of a sensor unit, whereby the signal quality and / or the sensitivity in the measurement volume can be increased. In experiments with the device according to the invention in a production plant using the electrical impedance spectroscopy method could be found in an astonishing way that in interaction with special electrode arrangements of the electrodes of a pair relative to each other, high-resolution and foreign bodies could be detected from non-electrically conductive materials, with a Construction of the device with two pairs of electrodes signal quality and the sensitivity of the device could be increased. However, metallic foreign bodies could also be detected in the measuring volume of the device according to the invention using the electrical impedance spectroscopy method. In this respect, the device according to the invention and the system according to the invention and the method according to the invention combined are suitable for the detection of metallic, electrically conductive foreign bodies, and metallic or non-metallic, electrically non-conductive foreign bodies. This solution has the advantage that the device according to the invention can also be used as a combined detector or as a combined detection method for a foreign body of an electrically conductive and a foreign body of an electrically non-conductive material.

In the automated production and filling process of food or animal feeds, it is possible with the incorporation of the device according to the invention into a production chain of a bottling plant and using impedance spectroscopy in the filling process to continuously convey the substrate with regard to undesired solid fragments, metallic or non-metallic, electrically conductive or non-electrically conductive monitor.

Preferably, the electrodes of the sensor elements with electrically conductive surfaces on the lateral surface of the cylindrical tube are electrically isolated from each other. The tube is advantageously designed in the form of an insulator made of an electrically non-conductive material, such as electrically non-conductive plastic, carbon, ceramic, glass or silicone. The connection of the electrodes via their conductive surfaces on the lateral surface of the tube is also advantageous, since in this embodiment, no parts of the electrodes protrude into the measuring volume, which could hinder the food or feed stream or could lead to interference in resistance measurement by means of impedance.

Advantageously, the electrodes of a sensor element are arranged at opposite points of the lateral surface of the cylindrical tube together lying on a straight line to each other. This means that the conductive surfaces of the electrodes of a pair of electrodes are arranged plane-parallel to each other, between the electrodes lies the measuring volume through which flows the food or feed. The plane-parallel aligned conductive surfaces of the electrodes of a pair of electrodes form with the intermediate measuring volume quasi a capacitor. The electrodes of a pair of electrodes of a sensor element are advantageously aligned with each other so that they enclose an angle of 180 °. In order to obtain a particularly good field coverage in the measurement volume, the electrodes of one electrode pair are aligned offset to one another with respect to the electrodes of another electrode pair in the radial direction of rotation of the lateral surface. Advantageously, the electrodes of one pair of electrodes are arranged offset to the electrodes of the other pair of electrodes in the radial direction of rotation of the lateral surface by 90 ° or in the embodiment of the measuring section by means of three sensor elements, that is three electrode pairs by 60 ° to each other. Depending on the requirements and the desired field coverage, the electrodes of one pair of electrodes can be arranged offset from one another to the electrodes of the other pair of electrodes in the radial direction of rotation of the lateral surface between 1 ° and 359 °.

In order to increase the measuring path in the measuring volume, the electrodes of one pair of electrodes to the electrodes of the other pair of electrodes in the longitudinal extent of the flow body arranged spaced apart on the lateral surface. This arrangement of the electrode pairs to each other also increases the signal quality and the sensitivity of the measuring system or the measuring device.

The electrode pairs advantageously register an impedance change in the form of a change in analog voltage values when passing the foreign body transported in the current between the electrodes electrically excited via a supply voltage and a generated excitation signal, which is measurable according to the invention. For the measurement, the analog voltage values are advantageously tapped from the electrodes, which drop across the measuring path and the current measuring resistor, and these analog voltage values are forwarded to the NI system with A / D converter, which converts the analog voltage values into digital values and which Excitation signal generated.

The above object is also achieved by a system comprising the device according to the invention. Furthermore, the system according to the invention comprises a digital multimeter with an A / D converter, which is referred to above and below as the NI system, which converts the analog voltage values into computer-processable digital values, and which generates an excitation signal for the electrodes. In addition, the system according to the invention comprises a connection box for coupling in the supply voltage and a sensor box, which has a power engineering and data link to the connection box, and which is connected via the connection box data technology with the NI system.

The sensor box also stimulates excitation of the electrodes via the excitation signal, which is communicated from the NI system to the sensor box via the junction box. The output of the excitation signal in the sensor box advantageously takes place via a voltage follower, in which case the tapping of the voltage values via the current measuring resistor (Rsense) as well as the measuring path ( R _Duty ) implemented. The sensor box and the junction box are preferably arranged in two separate subsystems, that is to say in separate housings, which are advantageously connected to one another in terms of data and power by a multi-shielded LAN cable. In order to make the system more advantageous in terms of interference, the sensor box and the connection box are particularly preferably designed to be single-housed, ie arranged in a dedicated housing, wherein preferably all components of the sensor box and the connection box are arranged on a common printed circuit board. Optionally, a filter stage can be integrated into the system for signal preprocessing, which suppresses interference components that are not caused by the excitation of the impedance measurement before the analog measured values are converted into the digitally processable data. By the signal preprocessing with the filter stage can advantageously disturbances, the measured variables in the measuring section ( R _Duty ) itself or on the way to the NI system, are filtered out, so that even very small particles, ie microorganisms can be detected, which would go down without integrated filter stage in measurement noise, ie in the interference.

As an impedance measurement, the system advantageously performs a resistance measurement, for which purpose a current, imparted by a voltage follower of the sensor box, is applied to the electrodes of the sensor device and when the electrodes are excited by means of an excitation signal, the resulting voltage drop in the form of voltage values via the current measuring resistor R _sense as well as the measuring section R _Duty tapped, this advantageously with at least one filter smoothes and the smoothed signal is transmitted from the sensor box via the connection box to the NI system. The voltage follower advantageously implements an impedance transformation using electrical energy, namely in the present case the excitation signal. Preferably, the excitation takes place with an alternating current in a frequency range between 5 to 30 kHz. More preferably, the excitation takes place with an alternating current in a frequency range between 8 to 20 kHz, and particularly advantageous is the excitation with an alternating current at a frequency of 10 kHz. The excitation with a frequency of 10 kHz thereby represents an advantageous compromise between the overcoming of double-layer effects on the electrode surfaces and a reasonable hardware outlay for signal handling and signal sampling. The excitation is advantageously carried out via an excitation signal whose voltage amplitude is preferably between 50 to 400 mV , Very particularly advantageous is the excitation via an excitation signal whose voltage amplitude is 250 mV.

In order to be able to detect a foreign body in the food or animal feed stream, an impedance average is advantageously calculated or measured in a test run for each food or animal feed formulation, wherein the impedance average for each recipe is preferably used as a reference value on a readable data memory or in a Database is stored, which are connected to the data-technically with the system according to the invention. Surprisingly, it has also been possible to show from the preceding experiments by the applicant of the present invention that for the individual formulations the impedance average around 50 Ω +/- 5 is at a constant level. By the provision According to the invention, the impedance average (resistive component) could be determined that changes in the cross-section of the substrate, for example large or small chunks of meat, or pieces of large or small pieces of vegetables, have no effect on the impedance average. Accordingly, the system according to the invention can advantageously be used universally without prior determination of the impedance mean value for various formulations in order to use these for foreign body determination in a wide variety of recipes.

The impedance average effectively forms a raw data set comprising the magnitude and imaginary part of the electrical impedance. With foreign body influence the current measuring resistance increases R _sense on, so based on the increase of the current sense resistor R _sense as well as over the measuring section R _Duty and advantageous with respect to the time course of the foreign body in a determinable measurement volume in a transported substrate current can be detected.

An inventive method for detecting a foreign body in a transported substrate stream of a food or a feed, using the inventive device, which is fluidly connected to a plant for the production and / or packaging of food or animal feed, and wherein the device is part of the system according to the invention is the technical teaching that upon detection of a foreign body in the food or feed at least one of the measurement volume of the flow body corresponding amount of food or feed by a downstream with the device fluidly connected to the discharge device delayed in time to the detection of the foreign body from the transported Electricity can be discharged. In order to discharge the contaminated with the foreign body food or feed via the discharge device from the manufacturing process, the Ausschleuseeinrichtung advantageously receives from the NI system or the NI system downstream control unit a signal, wherein upon receipt of the signal through the Ausschleuseeinrichtung the contaminated food or feed in the volume corresponding to the measuring volume of the device, is discharged with the foreign body from the substrate stream. In order to be able to control the discharge of the contaminated with the foreign body substrate, the timing of the foreign body when passing through the measuring path and the speed of the substrate current in the processing of the signal sent by the NI system to the Ausschleuseeinrichtung be considered to time offset after passing the measuring section on the downstream of the measuring device according to the invention downstream Ausschleuseeinrichtung the sample volume corresponding to the measuring volume auszuschleusen with the foreign body from the substrate stream and this optionally collected for follow-up in a container.

In addition to the detection of electrically conductive and electrically non-conductive foreign bodies in the substrate current, the present invention, namely the device according to the invention, the system according to the invention and the method according to the invention are also suitable for the detection of gas inclusions in the substrate flow, such as air. Thus, with the present invention, for example, fermentation processes can be detected in the substrate, which can provide information about the freshness of the food or food used, for example. Also, a deviation from the known impedance mean for a formulation of a food or feed can provide information about the moisture content of the recipe.

In order to avoid repetition here regarding the advantages of the system according to the invention or of the method according to the invention, reference is made to the description of the advantageous embodiment of the device according to the invention and it is used in full.

Further measures improving the invention will be described in more detail below with the description of preferred embodiments of the invention with reference to the figures. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination. It should be noted that the embodiments shown in the figures have only descriptive character and are not intended to limit the invention in any way.

• 1 eine schematische Skizze einer erfindungsgemäßen Vorrichtung mit einer Sensoreinheit, umfassend ein Sensorelement mit einem Elektrodenpaar, beim Durchlaufen von zwei Fremdkörpern in einem Substratstrom,
• 2 die Vorrichtung aus 1 in einer schematischen Schnittansicht senkrecht zur Längsachse AA beim Durchlaufen der zwei Fremdkörper in dem Substratstrom,
• 3 eine schematische Skizze einer erfindungsgemäßen Vorrichtung mit einer Sensoreinheit, umfassend zwei Sensorelemente mit je einem Elektrodenpaar, beim Durchlaufen von zwei Fremdkörpern in einem Substratstrom,
• 4 die Vorrichtung aus 3 in einer schematischen Schnittansicht beim Durchlaufen der zwei Fremdkörper in dem Substratstrom,
• 5 eine schematische Skizze einer erfindungsgemäßen Vorrichtung mit einer Sensoreinheit, umfassend vier Sensorelemente mit je einem Elektrodenpaar, beim Durchlaufen von zwei Fremdkörpern in einem Substratstrom
• 6 die Vorrichtung aus 5 in einer schematischen Schnittansicht beim Durchlaufen der zwei Fremdkörper in dem Substratstrom, und
• 7 eine schematische Skizze eines erfindungsgemäßen Systems, umfassend die erfindungsgemäße Vorrichtung.

Show it:

• 1 1 a schematic sketch of a device according to the invention with a sensor unit, comprising a sensor element with a pair of electrodes, when passing through two foreign bodies in a substrate flow,
• 2 the device off 1 in a schematic sectional view perpendicular to the longitudinal axis AA when passing through the two foreign bodies in the substrate stream,
• 3 1 is a schematic sketch of a device according to the invention with a sensor unit, comprising two sensor elements, each with a pair of electrodes, when passing through two foreign bodies in a substrate flow,
• 4 the device off 3 in a schematic sectional view when passing through the two foreign bodies in the substrate stream,
• 5 a schematic sketch of a device according to the invention with a sensor unit, comprising four sensor elements, each with a pair of electrodes, when passing through two foreign bodies in a substrate current
• 6 the device off 5 in a schematic sectional view when passing through the two foreign bodies in the substrate stream, and
• 7 a schematic sketch of a system according to the invention, comprising the device according to the invention.

In the different figures, the same parts are always provided with the same reference numerals, which is why they are usually described only once.

1 shows a schematic sketch of an inventive device 1 with a sensor unit 7 , The device 1 is as a flow body 5 in the form of a cylindrical tube 6 trained and has a specific measurement volume 4 on. The measuring volume 4 calculated from the cross section of the cylindrical tube 6 whose standard nominal width is advantageously 65 or 80 cm, and from the length of the cylindrical tube 6 , The sensor unit 7 in this embodiment comprises a sensor element 8.1 with two electrodes 9.1 and 9.2 , which together form a common electrode pair. The device 1 is designed for installation in a production plant for producing a feed or food, which is designed in the form of a pipe system through which a feed or food substrate stream is conveyed. The device 1 includes for this purpose at both ends of the cylindrical tube 6 advantageous coupling pieces (not shown here), bringing the device 1 can be easily integrated into the pipe system of the production plant, or existing production plants with the device according to the invention 1 can be easily retrofitted. The two electrodes 9.1 and 9.2 form as a common electrode pair, the sensor element 8.1 the sensor unit 7 , where the electrodes 9.1 and 9.2 each with electrically conductive surfaces 11 on the lateral surface 12 of the cylindrical tube 6 are arranged. The conductive surfaces 11 the two electrodes 9.1 and 9.2 are perpendicular to the longitudinal axis AA arranged to each other and are through the lateral surface 12 electrically isolated from each other. The two electrodes 9.1 and 9.2 serve according to the invention for the detection of a foreign body 2 . 3 , present in 1 go through two foreign bodies 2 . 3 with the substream in the flow direction parallel to the longitudinal axis AA passing through the two arrows at the beginning and at the end of the cylindrical tube 6 in the 1 is shown, the device according to the invention 1 , At the foreign bodies 2 . 3 may be electrically conductive and / or electrically non-conductive foreign body 2 . 3 act. The two foreign bodies 2 . 3 in the present case run through the measuring volume with the substrate flow 4 the device 1 at different positions of the cylindrical tube 6 and in particular at different positions, the gap between the two electrodes 9.1 and 9.2 , The electrically isolated separation of the two electrodes 9.1 and 9.2 takes place advantageously by the formation of the cylindrical tube 6 from an electrically very low or electrically non-conductive material, for example in the form of a plastic tube. The arrangement of the electrodes 9.1 and 9.2 with their conductive surfaces 11 on the lateral surface 12 of the cylindrical tube 6 offers opposite measuring electrodes, which are in the volume of the cylindrical tube 6 intervene, the advantage that a mechanical contact between the substrate current and the electrodes 9.1 and 9.2 can be ruled out, whereby a background noise in the impedance measurement can be excluded to a considerable extent. The space between the two electrodes 9.1 and 9.2 determines a punctual measuring section R _Duty , whose value for the signal conversion of an event, namely the passage of a foreign body 2 . 3 in the subtrate stream, in conjunction with that at the excited electrodes 9.1 and 9.2 tapped voltage values via the current sense resistor R _sense serves. By means of the measuring volume 4 in conjunction with the signal conversion, the volume of the foreign body 2 . 3 contaminated substrate are determined in a timely and punctually in the substrate current. If one adds to these values nor the flow rate of the substrate current, that can be done with the foreign body 2 . 3 contaminated substrate after the flow through the device according to the invention 1 advantageously over a downstream of the device 1 in the production facility integrated Ausschleuseeinrichtung be removed from the substrate stream.

2 shows the device 1 out 1 in a schematic sectional view perpendicular to the longitudinal axis AA when passing through the two foreign bodies 2, 3 with the substrate current. Between the two electrodes 9.1 and 9.2 of the sensor element 8.1 the sensor unit 7 When a voltage is applied, an electric field, which is a measuring window, is generated 50 certainly, inside the zy lindrischen tube 6 educated. The measurement window 50 covers present in 2 not the entire cross section of the cylindrical tube 6 from. The in 1 right anterior foreign body 3 does not pass through the measurement window due to the field distribution of the electric field 50 , in the case of this foreign body 3 whose detection with the sensor unit 7 , which includes only one electrode pair, is not possible. On the other hand, the in happens 1 left posterior foreign body 2 that between the electrodes 9.1 and 9.2 formed measuring windows 50 inside the tube 6 and can be detected as such, passing through the foreign body carried in the substrate stream 2 between the electrodes electrically excited via a supply voltage and an excitation signal 9.1 and 9.2 an impedance change in the form of a change in analog voltage values across a current sensing resistor R _sense 18 is measurable. In particular, the analog voltage values from the electrodes are used 9.1 and 9.2 be tapped over the test section R _Duty 17 and the current sense resistor R _sense 18 fall off.

In 3 is a device according to the invention 1 with a sensor unit 7 with two sensor elements 8.1 and 8.2 each with a pair of electrodes, each with two electrodes 9.1 . 9.2 and 9.3 . 9.4 , shown schematically when passing through two foreign bodies 2,3 in a substrate stream. Unlike the device 1 from the 1 and 2 in which the measuring section R _Duty 17 punctually between the electrodes 9.1 and 9.2 of a sensor element 8.1 is formed, is the measuring section R _Duty 17 the sensor unit 7 the device 1 in 3 between the two sensor elements 8.1 and 8.2 each formed with a pair of electrodes, whereby the measuring window 50 and 51 in longitudinal extension and parallel to the longitudinal axis AA in the measuring volume 4 of the cylindrical tube 6 be stretched, which increases the signal quality and the sensitivity of the impedance measurement.

As seen from the schematic sectional view perpendicular to the longitudinal axis AA the device 1 out 3 in the 4 can be seen, are the two pairs of electrodes with the electrodes 9.1 . 9.2 and 9.3 . 9.4 the two sensor elements 8.1 and 8.1 not only in the longitudinal direction and parallel to the longitudinal axis AA but these are also in the radial direction of rotation (by the rotating arrow on the right side of the cylindrical of the tube 6 shown in the figure) of the lateral surface 12 of the cylindrical tube 6 offset from one another on the lateral surface 12 arranged. In the present case are the two electrodes 9.1 . 9.2 of the first sensor element 8.1 (in the 3 the left sensor element 8.1 ) relative to the two electrodes 9.3 . 9.4 of the second sensor element 8.2 (in the 3 the right sensor element 8.2 ) in the radial direction of rotation of the lateral surface 12 of the cylindrical tube 6 offset by 90 ° to each other on the lateral surface 12 arranged. Between the two electrodes 9.1 . 9.2 of the first sensor element 8.1 and the two electrodes 9.3 . 9.4 of the second sensor element 8.2 the sensor unit 7 Whenever a voltage is applied, an electric field is generated, the two measuring windows aligned perpendicular to one another and lying across each other 50 and 51 certainly, inside the cylindrical tube 6 educated. The two measurement windows 50 and 51 cover present in 4 almost the entire cross section of the cylindrical tube 6 but still in the upper and lower right and left of the tube 6 are not covered by the measurement window covered zones. The in 3 right anterior foreign body 3 at least partially passes through the second sensor element due to the field distribution of the electric fields 8.2 formed measuring windows 51 , in the case of this foreign body 3 opposite the measuring device 1 out 1 and 2 an improved detection of one with the substrate current through the measuring device 1 guided foreign body 2.3 is possible, but due to the incomplete coverage of the foreign body 3 with the through the two sensor elements 8.1 and 8.2 formed measuring window 50 and 51 , the quantity of foreign body 3 can not be determined exactly. However, with the partial covering of the foreign body 3 with the second measurement window 51 of the second sensor element 8.2 at least the event that a foreign body is carried in the substrate current detected. On the other hand, the in happens 3 left posterior foreign body 2 both between the electrodes 9.1 . 9.2 and 9.3 . 9.4 formed measuring window 50 and 51 with full coverage of the two measurement windows 50 and 51 and can be detected as such, passing through the foreign body carried in the substrate stream 2 between the electrodes electrically excited via a supply voltage 9.1 . 9.2 and 9.3 . 9.4 the two sensor elements 8.1 and 8.2 in each case an impedance change in the form of a change of analog voltage values via the current measuring resistor R _sense 18 is measurable. Preferably, the current measuring resistor is thereby R _sense 18 about changing the analog voltage values simultaneously at the electrodes 9.1 . 9.2 and 9.3 . 9.4 both sensor elements 8.1 and 8.2 tapped. In addition to the enlargement of the measuring section R _Duty 17 can be through the distribution of the electrodes 9.1 . 9.2 and 9.3 . 9.4 and their arrangement relative to each other in the radial direction of rotation of the lateral surface 12 of the pipe 6 the signal quality and the sensitivity of the device 1 of the 3 and 4 opposite the device 1 of the 1 and 2 be increased by a multiple, since the overlap of orthogonal to each other formed measuring window 50 and 51 , the probability that a foreign body entrained in the substrate current 2.3 at least one of the measurement windows 50 or 51 happened, is increased. However, with this embodiment of the device 1 foreign body 2.3 that is outside the two measurement windows 50 and 51 the measuring section R _Duty 17 happen, not be detected.

To the signal quality and / or the sensitivity of the device according to the invention 1 are still to increase as in the 5 and 6 shown, three sensor elements 8.1 . 8.2 and 8.3 , one sensor unit 7 forming, each having a pair of electrodes of two electrodes 9.1 . 9.2 and 9.3 . 9.4 and 9.5 . 9.6 formed in the longitudinal extent of the cylindrical tube 6 parallel to the longitudinal axis AA , over the entire length of the pipe 6 on the lateral surface 12 are arranged, reducing the length of the pipe 6 equal to the measuring section R _Duty 17 is. The electrodes 9.1 . 9.2 and 9.3 . 9.4 and 9.5 . 9.6 the three sensor elements 8.1 . 8.2 . 8.3 are also in the radial direction of rotation of the lateral surface 12 of the cylindrical tube 6 offset by 60 ° to each other on the lateral surface 12 arranged, in each case between a pair of electrodes upon excitation of the electrodes 9.1 . 9.2 and 9.3 . 9.4 and 9.5 . 9.6 by means of a supply voltage and an excitation signal in each case an electric field in the form of a measuring window 50 . 51 or 52 is built. As in the schematic representation in 6 shown, penetrate the three measuring windows formed 50 . 51 . 52 almost the entire cross section of the tube 6 , so that with this construction of a multi-electrode arrangement at each position where a foreign body 2.3 the measuring section R _Duty 17 goes through, this from the sensor unit 7 can be detected.

Finally, in 7 an inventive system 100 which is the device according to the invention 1 includes, shown schematically. The system 100 includes three skin components 13 . 14 . 16 , An NI system 13 , which is a digital multimeter with A / D converter, and a measuring front end 200 , which in the present case is constructed dioecious, with a junction box 14 and a sensor box 16 , The NI system 13 forms the heart of the system 100 , It converts the analog voltage values via the current sense resistor R _sense 18 be converted into computer-processable digital values. It also generates the NI system 13 an electrical stimulus, with which the feed or food to be examined via the sensor unit 16 that is, over the electrodes 9.1 . 9.2 . 9.3 . 9.4 and or 9.5 . 9.6 , along the measuring section R _Duty 17 in the device 1 is stimulated. So that both the current sense resistor R _sense 18 tapped and the electrical stimulus is generated with a corresponding sensitivity and transmitted to the measuring section, the measuring front end 200 the measured quantities from the sensor unit 7 to be understood and best protected by the NI system 13 convey. Only after analog-to-digital conversion in the NI system 13 the measured quantities are fixed and safe from disturbing influences of the surrounding product environment, such as mechanical influence, electromagnetic influence, temperature or, for example, atmospheric humidity. To ensure this is the measuring front end 200 in the present case constructed in a dioecious manner, wherein via the connection box 14 the sensor box 16 with the NI system 13 connected is. In addition, the connection box is used 14 for coupling the supply voltage from a voltage source 15 , To a trouble-free connection between the connection box 14 and the sensor box 16 To ensure these are a multi-shielded LAN cable 60 Data and current or voltage technology connected to each other. In the sensor box 16 will be the one from the connection box 14 over the LAN cable 60 coupled supply voltage of 12 volts via a DCDC converter 80 transformed into a 15 volt voltage and this is the same as that of the NI system 13 over the connection box 14 to the sensor box 16 mediated excitation signal via a voltage follower 70 to the sensor unit 7 output. The excitation is advantageously carried out with an alternating current at a frequency of 10 kHz. In addition, in the sensor box 16 the tapping of the voltage values via the current measuring resistor R _sense 18 as well as the measuring section R _Duty 17 implemented. Optionally, for signal preprocessing, a filter stage in the system 100 are integrated (not shown here), which suppressed already before the conversion of the analog measured values into the digitally processable data noise components, which are not caused by the excitation of the impedance measurement. By the signal preprocessing with the filter stage can advantageously disturbances that the measured variables in the test section R _Duty 17 yourself or on the way to the NI system 13 be filtered out, so that even very small particles, ie small alien bodies can be detected, which would go down without integrated filter stage in the measurement noise, ie in the interference. The system according to the invention 100 with the device according to the invention 1 is therefore also for the detection of minute airborne particles or small air inclusions, for example, in medical fluids, such as infusion solutions, used and can thus be used for quality control of such medical fluids.

The generation of the excitation signal as well as the processing of the measured variables is carried out using a system especially for the invention 100 developed software. The algorithm underlying the software is designed so that it can be adapted to improve the measurement accuracy.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19981337717 [0004]
• DE 200620002507 [0005]

Claims (11)

Device (1) for detecting a foreign body (2,3) in a measuring volume (4) in a transported substrate stream of a foodstuff or animal feed, wherein the measuring volume (4) is a flow body (5) in the form of a cylindrical tube (6), by means of a sensor device (7) with at least one sensor element (8.1) with at least two electrodes (9.1, 9.2), characterized in that the sensor element (8.1) detects the foreign body (2, 3) by means of impedance measurement. Device (1) according to Claim 1 , characterized in that the sensor device (7) has at least one second sensor element (8.2) with at least two electrodes (9.3,9.4), wherein the first sensor element (8.1) and the second sensor element (8.2) by means of impedance measurement of the foreign body (2,3 ) on a measuring section (R _Duty ) lying between the two sensor elements (8.1) and (8.2). Device (1) according to Claim 1 or 2 , characterized in that the two electrodes (9.1,9.2) of the first sensor element (8.1) or the two electrodes (9.3,9.4) of the second sensor element (8.2) each form an electrode pair, wherein the electrodes (8.1,8.2,9.3,9.4 ) each with an electrically conductive surface (11) on the lateral surface (12) of the cylindrical tube (6) are arranged, wherein conductive surfaces (11) of the electrodes (8.1,8.2,9.3,9.4) by the lateral surface (12) electrically insulated are separated from each other. Device (1) according to Claim 2 or 3 , characterized in that the two electrodes (9.1,9.2) of the first sensor element (8.1) in the radial direction of rotation of the lateral surface (12) of the cylindrical tube (6) relative to the two electrodes (9.3,9.4) of the second sensor element (8.2) to each other on the lateral surface (12) are arranged. Device (1) according to one of Claims 2 to 4 , characterized in that the electrodes (9.3,9.4) of the second sensor element (8.2) in the longitudinal extent parallel to the longitudinal axis AA of the flow body at a distance from the electrodes (9.1,9.2) of the first sensor element (8.1) on the lateral surface (12) are arranged, wherein the distance between the two sensor elements (8.1) and (8.2) determines the measuring path (R _Duty ). Device (1) according to one of the preceding claims, characterized in that when passing through the foreign body (2,3) transported in the substrate current between the electrodes electrically energized via a supply voltage (9.1,9.2,9.3,9.4,9.5,9.6) an impedance change in Form of a change of analog voltage values via a current measuring resistor (Rsense) is measurable, in particular the analog voltage values are tapped from the electrodes (9.1,9.2,9.3,9.4,9.5,9.6), over the measuring path (R _Duty ) and the current measuring resistor (Rsense) fall off. System (100), comprising the device (1) according to one of Claims 1 to 6 , an NI system with A / D converter (13), which converts analog voltage values into computer-processable digital values, and which generates an excitation signal for the electrodes (9.1,9.2,9.3,9.4,9.5,9.6), a connection box (14 ) for coupling the supply voltage (15) and a sensor box (16), the current and data technology with the connection box (14) is connected and the excitation signal to excite the electrodes (9.1,9.2,9.3,9.4,9.5,9.6) on receives the connection box (14) from the NI system (13) and which receives the tapping of the voltage values through the electrodes (9.1.9.2.9.3.9.4.9.5.9.6) via the current measuring resistor (Rsense) (18) and over the measuring path ( R _Duty ) (17). System (100) after Claim 7 , which performs a resistance measurement as an impedance measurement, applying thereto a current to the electrodes (9.1.9.2.9.3.9.4.9.5.9.6) of the sensor device (7) and smoothing the resulting voltage drop with filters and smoothing the signal from the sensor box (16 ) via the connection box (16) to the NI system (13). System (100) after Claim 7 or 8th , characterized in that impedance mean values for different food or animal feed recipes are stored on a readable data memory (19) or in a database (20) and the data memory (19) or the database (20) data-technologically connected to the system (100) is. Method for detecting a foreign body (2, 3) in a transported stream of a foodstuff or animal feed, using the device (1) according to any one of Claims 1 to 6 , which is fluidly connected to a plant for the production and / or packaging of food or feed, and wherein the device (1) part of the system (100) according to one of Claims 7 to 9 characterized in that upon detection of a foreign body (2,3) in the food or feed at least one of the measuring volume (4) of the flow body (5) corresponding amount of the food or feed by one with the device (1) downstream fluidly connected discharge device can be removed from the transported stream with a time delay to the detection of the foreign body (2,3). Method according to Claim 10 , characterized in that an electrically conductive and / or an electrically non-conductive foreign body (2,3) are detected and can be discharged from the food stream or the feed stream.

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