DE202006020496U1 - Sensor device for detecting electromagnetically detectable items to be conveyed and sorting device with such a sensor device - Google Patents

Abstract

The invention relates to a sensor apparatus (14) having a plurality of sensors (100) for detecting electromagnetically detectable conveyed goods (15, 16), having an associated conveying device (12) which moves conveyed goods (13) past the sensors (100) in a conveying plane and in a direction of movement (116), having a device (102) for generating an alternating electromagnetic field, wherein the sensors (100) each have at least one pair of detector coils (104, 106) which are connected to an evaluation device (20) for determining a differential signal between the coils (104, 106) in a pair for the purpose of detecting conveyed goods (15) which deform the alternating field on the basis of their material properties, and is characterized in that the two detector coils (104, 106) in the pair are arranged in such a manner that they have cross-sectional areas which are parallel to the conveying plane and have centroids (M, M') which have been displaced relative to one another, and the connecting line (L) between the centroids (M, M') is oblique to the direction of movement (116) of the conveyed goods (13). Furthermore, the invention relates to an apparatus (10) for the automated sorting of electromagnetically detectable fractions of a stream of conveyed goods (13) using such a sensor apparatus (14).

Description

The The invention relates to a sensor device according to the preamble of Claim 1 and a sorting device with such a sensor device according to claim 19.

In Many areas of recycling is automated sorting required as recycled material recycling required. It should not only the largest possible quantities of conveyed per Time to be processed, but the sorting should also be great Yield and low error rate. It may be at the Conveyed material z. For example, to deal with glass, in which there are still metal fractions are located, for. B. bottle caps or other bottle or glass closures. It may be in the conveyed z. B. also in a shredder Crushed old cars deal with fractions of various metals or other recyclables that are accessible for recycling to be made. Also a sort of garbage would be a possible application, eg. B. an aluminum fraction sort out. Furthermore, it can also be conveyed to deal with different mineralogical fractions that are different have electromagnetic properties and sorted for further processing should be. Not exhaustive are as applications also mentioned the sorting of metal residues in wood recycling fractions in the fibreboard industry and the Locating metals in food streams in bulk form.

It In the prior art, various automated devices are known and methods are known which take over these sorting tasks. The devices have for this purpose sensors, by whose sensory monitored Area the conveyed material is moved. The sorted out Parts are suitable for sorting criteria detected sensors detected, and by means of the sensor information a separator is controlled to selectively sorted out as one Detect recognized part of the conveyed. In glass is z. B. known, a sorting of the glass color with optical Make sensors that recognize the glass color, and z. B. brown glass separate from white and green glass.

In particular, devices and methods are known which separate individual fractions according to their distinguishable electromagnetic properties. For this purpose, an electromagnetic alternating field is used, through which the material to be sorted is moved. A change of the alternating field through one of the parts is detected, and then the part sorted out. Such a sorting device with a generic sensor device discloses the EP 0 353 457 B1 , The frequency of the alternating field is freely selectable in many areas, z. B. with a frequency between 5 kHz and 2 MHz.

The Sensors of the sensor device shown there consist of two oppositely wound detector coils in which an external alternating field is the same induced large but opposite alternating voltages. in the undisturbed state, the alternating voltages cancel each other suitable difference formation exactly to zero. If, however, metallic Parts get into the measuring range of the detector coils, superimposed The homogeneous alternating field is an inhomogeneous field, that of the alternating field is induced in the metal parts. For the sensors this is a change of the alternating field. The first z. B. as homogeneous as possible generated alternating field now has an inhomogeneous disturbance due to an induced magnetic field on. As a consequence, in the two detector coils of a sensor now no equal, canceling AC voltages induces more, but at subtraction results in a significant non-zero signal value.

The Spatial resolution of these sensors of the generic Sensor device is determined by the size of each Sensors or by the size of the contained therein Coil pairs determined. Also controlled by the sensors Separating device, for. B. a series arrangement of exhaust nozzles, can only in this limited spatial resolution be controlled. This is particularly disadvantageous if the parts to be sorted can be smaller than the sensors, z. B. if the conveyed granules with a small particle size is present. It can then z. B. a closely adjacent to a metal part lying non-metal inadvertently from the controlled blowing nozzle to be sorted out with. It creates an undesirable Übersortierung. To achieve a higher resolution, would have to the sensors are downsized. This is on the one hand in the production consuming and would make the sensors more expensive. In addition, would the detection range of the sensors with increasing miniaturization decrease, because the effective area for measuring changing electromagnetic Field lines would become smaller. Furthermore, the generic Sensor device large metal parts that over several adjacent sensors extend, do not detect correctly. Under unfavorable circumstances, the exhaust nozzles wrong or not addressed.

It is therefore the object of the present invention to a constructive simple and inexpensive way a sensor device to create sensors with higher resolution, the Reliable parts of different sizes detected. Furthermore, a sorting device is available with the better and more reliable sorting results can be achieved.

This object is achieved with a generic sensor device with the characterizing Characteristics of claim 1 and with a sorting device according to claim 19 solved.

After that the sensor device according to the invention has several Sensors on whose detector coils are arranged in pairs, that their cross-sectional surfaces parallel to the conveying plane have mutually shifted centroids, and the connecting line between the centroids is oblique to the direction of movement of the conveyed material.

The Detector coils can basically a have any shape. The invention only requires that the two Detector coils of a couple different on the z. From one Metal part disturbed alternating field react. Furthermore, the should Sensor signal and the location of the crossing of the sensor detectable do. This is achieved by looking at the cross-sectional areas the detector coils of a pair in a plane parallel to the conveyor plane of the conveyed good at least partially do not cover by the centroids of these cross-sectional areas are shifted against each other. Furthermore, the connecting line between these centroids obliquely to Movement direction stand. With this symmetry break can be easy be distinguished evaluating sensor signal, whether z. B. a metal part cross the sensor to the left or right of the center of the sensor. For example, if the connecting line were parallel to the Moving direction would be a left of the sensor center the part crossing the sensor is not from a right of the sensor center, the sensor crossing part differ can be.

you Imagine two identical circular ones Planar coils as a detector coil pair before whose area vectors are aligned perpendicular to the conveying plane. After the invention are the two circular area centers of the detector coils spaced apart from each other and the connecting line is obliquely to the direction of movement, so that the two coils do not overlap in their circular cross-sectional areas, but offset both in the direction of movement and transversely thereto are arranged to each other.

It is with the inventive design with Advantage achieved that a part, due to its material property changed the alternating field, so z. B. in response to the alternating field is a secondary alternating magnetic field trains or z. B. has a permanent magnetic field from home, and which is moved past the sensor, in chronological order first the detector coil arranged further in the direction of movement affected. In this coil is first a suitable Difference formation induces non-lifting voltage. Only after comes in the direction of movement behind arranged detector coil in the influence of field inhomogeneity. The suitably formed Difference signal of the detector coil pair reflects this information again.

The Formation of the conveyor is within the scope of the invention largely arbitrary. The sensor device may, for. B. also on a Fall distance be arranged, the z. B. a conveyor like a conveyor belt or a chute connects. Change the direction of movement and the orientation of the conveyor plane in this special case on the fall path of the conveyed material part. Other conceivable delivery devices are known in the art known.

It it is possible for a sensor to have several pairs of detector coils has, for. B. four detector coils. In the following, however, will to simplify the explanations and without restriction The general public of a detector coil pair per sensor assumed. One pair of detector coils per sensor will also be regarded as a preferred embodiment, because so all required information can be obtained.

As already stated at the outset, the shape of the detector coils be chosen arbitrarily. The detector coils of a sensor can z. B. also a different shape, size or orientation in the room. If the sensor z. B. due such shape differences in the undisturbed alternating field Difference signal should be significantly different from zero, can z. B. electronically zero balance can be made to the sensitivity to optimize. Also inhomogeneities of the undisturbed alternating field could be reconciled, albeit with effort. With advantage However, the features of claim 2 are proposed. at essentially mirror-symmetrical design of the detector coil pair is the inductive coupling to the alternating field for both Detector coils largely identical. Both coils are the same subjected to total magnetic flux, provided the alternating field is approximately homogeneous from the perspective of the detector coils. Therefore, choosing the appropriate, that is taking into account the signs of the detector coil voltages Difference calculation automatically approximates a zero balance.

Prefers before the evaluation, first from the two detector coil voltages generates a total signal in pairs, the negative and positive values can accept. It is z. B. a measuring amplifier usual Type used. The evaluation then takes place on the total signal of the Sensor.

It can z. B. from the time length of the positive, d. H. with phase, and negative, d. H. antiphase, signal components of the Total signal and the evtll. in between residence time be closed in large parts to the time that detected this Part needed to the sensor or the individual detector coils to cross. This time is at central crossing greater than crossing the edge of the Sensor. Due to the inclination can continue unambiguously whether the part to the left or right of the sensor center is the Sensor has crossed. In addition to the temporal Length of the positive or negative signal component, the at Inclination z. B. may vary, depends also the location of the zero crossing from the place of crossing over from the sensor. Also from this it can be calculated, at which point the sensor was crossed.

According to the invention So from the evaluation of the throughput times of a conveyed good for one and / or the other of the detector coils of a Pair, possibly linked to the position of the zero crossing and knowing the inclination, the place of passage be determined very accurately. It is thus a resolution below the width of the sensor or the coil pair possible. The Resolution is now no longer by the sensor or Coil size determined, but essentially by the accuracy of the skew, the accuracy the measurement of the sensor signals and the accuracy of the evaluation the time course. In this way, with sensors otherwise same size a multiple higher Spatial resolution can be achieved, and it can, for. B. distributed to the sensor width and the sensor locally associated exhaust nozzles due to the information only a sensor are accurately controlled.

Further advantageous embodiments are in the subclaims specified.

Especially it is with the sensors according to the invention at appropriate training of the evaluation possible, to obtain an image of at least the contour of the part that the sensor device crosses. The sensors speak particularly sensitive to the entry or exit of a part in or from the sensor area, while z. B. the sensor when fully covered, essentially none of zero deviating signal provides more. In temporal pursuit of the Development of the sensor signal and application from other areas known interpolation method and plausibility checks a detailed image of the detected part can be obtained. Advantageously, therefore, the features of claim 17 are proposed. The evaluation of the time course of the signals of several neighboring Sensors can produce a relatively detailed picture of the shape and the To deliver the size of the detected part. It can so z. B. reliably detected, whether a large, planar object passes over the sensor device, or z. B. a long, thin object. This holds considerable Advantages over the usual single-sensor-oriented Evaluation. Based on this pictorial information can namely z. B. suitable or a plurality suitable positioned exhaust nozzles are controlled to z. B. not to inflate an object by its edge, causing the part would essentially only be set in rotation, but to affect the geometric center of gravity of the part. By suitable controllable training of the exhaust nozzles can, for. As well as the Ausblasimpuls adapted to the part size be, so z. B. application of a strong Ausblasimpulses for large parts and a smaller blow-out pulse for small pieces. It can thereby be the energy expenditure minimize.

The Sensors could z. B. in any distribution in the Sensor device may be arranged. For the evaluation and the control of the associated separation device is but disadvantageous. Advantageously, according to claim 3, the sensors of the sensor device Therefore, arranged in a row perpendicular to the direction of movement the moved past Fördergutstromes stands. This is the running time of the parts from the sensor to the effective range of the separator for all sensors in the same line and the controller the separator simplifies.

The Detector coils could z. B. as circular coils with offset Focuses be trained. It could z. B. several Detector coil pairs per sensor be provided. According to claim 4 However, each sensor has only two detector coils, the advantage D-shaped wound and spaced apart are. The two coils of a pair can z. B. in opposite directions be wound, a balance can also be with the sense amplifier respectively.

The alternating field could z. B. generated by an extending over all sensors exciter coil. As a rule, however, there is then no spatially very homogeneous field, so that the voltages induced in the detector coils of a pair cancel out only inadequately. Furthermore, z. For example, Fe materials or other magnetizable materials in a larger alternating field comprising multiple sensors can result in significant field line constrictions that also produce signals on adjacent but not traded detector coil pairs. Cross-sensitivity becomes unacceptable for some applications. Advantageously, therefore, according to claim 5 each sensor associated with an excitation coil. In particular, with the further advantageous features of claims 6 and 7 can be an improvement of the field homogeneity be obtained across the sensor coils.

the same purpose serve the advantageous features of claim 8. When arranging all coils in the same plane are possible disturbing influences by sensor coils of neighboring sensors.

The inventive sensor device could z. B. composed of a suitable number of individual sensors be. According to claim 9 but is provided with advantage that several Sensors grouped together on a fine conductor board are. The layout of the board allows the coils to be very accurate can be designed, and also the manufacturing can be done with high precision respectively. The use of boards allows an accurate and fast Positioning of the sensors in the sensor device. The sensor device can z. B. composed of a single, all sensors bearing board are. But it can also be composed of several smaller sensor boards be. An advantage of using smaller sensor boards is in that variable widths of Fördergutstromes or the conveyor can be covered by adding more sensor boards. A sensor board can z. B. have a linear array of five sensors. With eight boards, the z. B. in a common housing can be accommodated, so z. B. a sensor device with a Sensor array composed of two lines each with twenty sensors become. Furthermore, the use of smaller sensor boards z. B. a modular design, the individual boards could z. B. be operated modular and evaluated. Another advantage of the boards results from the possibility of the coils, So both the excitation and the detector coils, in modern Fine conductor technology and thus very high geometric accuracy manufacture.

disturbing Leave interaction between the coils of adjacent sensors decrease further with the advantageous features of claim 10. The excitation coils are operated in frequency and in phase, z. In a range selected between 5 kHz and 1 MHz. It is characterized z. B. ensures that no crosstalk between adjacent sensors is detected, among others also because each sensor has largely equivalent sensor neighbors whose influence is due to the pairwise arrangement the detector coils in sum can essentially cancel. Less environmental disturbances means at the same time improved measuring accuracy and higher Sensor sensitivity.

With The features of claim 13 will be a possible disorder further reduced by adjacent sensors. Every sensor sees left and right next to you, possibly also before or behind him, an identical neighborhood. Point symmetry at each Sensor center would be optimal from a mathematical point of view. The ideal symmetry comes close to the features of claim 13.

To over the entire width of the sensor device as possible complete detection z. B. of metal parts, could the sensors z. B. as close as possible to be ordered. Advantageously, the sensors are as claimed 11 arranged in several staggered rows, z. B. standing on a gap. Multiple lines of sensors can also be used to advantage, results of the sensors in the one line to check for errors by matching with results of the sensors in a second line.

The Range and sensitivity of the sensors can be increased according to claim 12, the detector coils and / or the excitation coils have a core, z. B. a ferrite core or a core of other suitable material.

Critical may be the edge regions of the sensor device because the outermost sensors only on one their sides have a neighboring sensor, so the disturbing influence for reasons of symmetry can not cancel. With the advantageous Features of claim 14 is achieved, however, that the outside However, in the line sensor lying approximately the same Neighborhood influences is exposed because next to it yet a sensor-empty exciter coil is arranged. You could In this marginal exciter coil also install another sensor, the z. B. is not used for evaluation. The disturbing influence of neighboring Excitation coils is much higher than the adjacent detector coils. The extra effort would be so far in no favorable Ratio to additionally achieved parasitic reduction.

It proves to be advantageous to choose the angle between the direction of movement of the conveyed material and the connecting line of the centroids or the plane of symmetry of the detector coils of a pair between 30 ° and 60 °, in particular to select the inclination of 45 °. If this angle was chosen to be very small, ie if the first detector coil is almost completely in front of the second detector coil in the direction of movement, it is difficult to distinguish whether the detected part has crossed the sensor to the left or right of the sensor center. This distinction is not possible if the plane of symmetry is exactly perpendicular to the direction of movement. For the other extreme case, namely that the plane of symmetry is parallel to the direction of movement, the sensor can detect large or centrally over the sensor running Fördergutteilchen very bad, because in both De be induced substantially equal voltages tektorspulen that can cancel out about zero. A local resolution below the sensor width succeeds at the preferred 45 ° in an optimal manner.

The Frequency of the alternating field can be selected within wide limits become. It can, for. B. a monofrequent field can be selected. However, the device for generating an electromagnetic is preferred Alternating field for generating a multifrequency alternating field is trained. The alternating field then provides an overlay several fields of different frequency. It can z. B. several discrete frequencies or z. B. uses a frequency band be. By using such a frequency-mixed alternating field ensures that regardless of conveyed material size and conveyed material always a reliable Detection takes place. As a rule, it can be stated be that for the detection of small filigree parts, z. B. of wires, higher frequencies advantageous are, for. B. between 150 and 500 kHz, while the detection in particular of iron parts preferably with lower frequencies succeed, z. B. less than 20 kHz. For generating such frequency-mixed Fields are applied to the excitation coils with appropriate signals.

The Advantages of the sorting device according to the invention According to claim 19 result from the advantageous features of used sensor device. The features of the claims 20 to 22 relate to further advantageous embodiments.

following the invention should continue based on embodiments are explained in the figures schematically and principled are shown. The same reference numerals stand for the same Parts. Show it:

1 a schematic representation of an embodiment of a sorting device according to the invention in side view,

2a . 2 B a schematic diagram of the operation of an embodiment of a sensor of the sensor device according to the invention ( 2a ) with several signal curves of the signal supplied by the sensor ( 2 B )

3 a schematic diagram of a possible circuit arrangement for the embodiment of a sensor according to 2a , and

4 a detail in plan view of an embodiment of a sensor device according to the invention in principle representation.

1 shows in a graphically simplified form the basic structure of a sorting device 10 for sorting out a metallic fraction 15 . 15 ' . 15 '' from a Fördergutstrom 13 , A conveyor belt 12 , in a manner not shown with conveyed 13 is charged, z. B. via an upstream chute, which in turn z. B. is loaded by a Fördergutvorrat transported conveyed 13 at a steady speed over one below the belt 12 arranged sensor device 14 time. Details of the sensor device 14 be based on the 2 - 4 will be explained later.

The conveyed goods 13 consists of a metallic fraction 15 and non-metallic conveyables 16 , In the example shown, the individual parts of the conveyed significant size differences. In alternative embodiments, e.g. B. also be preceded by a screening step or the conveyed already present by a suitable treatment in a uniform size.

The sensor device 14 is via a data bus 18 to an evaluation and control device 20 connected. The task of this evaluation and control device 20 is that of the sensor device 14 supplied sensor data to evaluate whether a part to be sorted passes the sensor area detected by the sensor device. Furthermore, the separation device is then suitable with a time delay 22 auszusteuern so that a detected metal part 15 ' is sorted out. The evaluation and control device 20 can z. B. also in the sensor device 14 to get integrated.

In the example shown, there is the separator 22 from a blower nozzle 24 , which are below the conveyor belt 12 is arranged at a fall distance. From the conveyor belt 12 falling conveyed items 15 ' can from the blower nozzle 24 be blown to exert a transverse accelerating pulse on the conveyed goods and it from the undisturbed trajectory to another, z. B. distracting far-reaching parabola. The blowing nozzle 24 is from a valve 26 mastered, z. B. from a solenoid valve. The control of the valve takes place via control lines 28 from the evaluation and control device 20 , The valve 26 is a compressed air hose 32 formed dominating, which compressed air from a compressed air reservoir 34 to the exhaust nozzle 24 leads. By timely and short-term opening of the valve 26 becomes one at the nozzle 24 passing conveyor particles 15 ' subjected to a Blasimpuls so that it is deflected by its undisturbed fall track and a separating edge 36 flies over to another conveyor belt 40 to be transported away, z. B. to a further processing or to a further sorting stage. On this transporting conveyor belt 40 are only still sorted metal parts 15 '' encountered. The exhaust nozzles 24 can z. B. be designed and controlled so that the intensity of the Ausblasimpulse adapted to be sorted just parts can be selected.

Non-sorted conveyed items 13 ' fall undisturbed on a third conveyor belt 42 that this reduced by the metal fraction Fördergutfraktion z. B. also transported to a further processing or sorting.

The conveyor belt 12 has a certain conveying width, and the conveyed goods 13 are distributed over this width across the sensor device 14 moved away. Therefore, the sensor device also extends 14 across the width of the conveyor belt 12 , Inside the sensor device 14 are distributed over the width of several sensors 100 arranged so that the width position of a metal part 15 on the conveyor belt 12 is detectable. Accordingly, the separator 22 a plurality of exhaust nozzles arranged in a row transversely to the direction of fall 24 on, which are arranged covering the Fallwegbreite suitably.

The evaluation and control device 20 is formed, one or more blow nozzles 24 to control the location of the sensor or sensors in the sensor device 14 are assigned, which is a conveyed 15 have detected. Furthermore, the evaluation and sensor device takes into account 20 the transit time of a particle from the sensor array 14 up to the blow-out position, ie until reaching the effective range of the blow-off nozzles 24 , It can be z. B. one with the evaluation and control device 20 be provided communicatively connected measuring device for detecting the belt speed. In the embodiment shown is to the pulley 27 of the conveyor belt 12 an angle encoder 29 arranged, which measures the instantaneous speed of the deflection roller, from which results the conveyor belt speed. The evaluation and control device 20 calculates with this instantaneous speed the correct time for the triggering of the purging nozzle 24 ,

There are further alternative embodiments of this embodiment of a sorting device 10 conceivable. So z. B. the conveyor belts 12 . 40 and 42 individually or all replaced by transport chutes or other conveyors, instead of the conveyor belts 40 and 42 can also be provided containers. The exhaust nozzles 24 could also be arranged above a fall path to a deflection of the sorted out fraction 15 ' . 15 '' away from the free fall way. The separating edge 36 could then be placed in a different position, it could also be omitted altogether, even if a reliable separation into individual fractions is guaranteed without them. Furthermore, it is possible to additional sensors z. B. to observe the fall distance of the transported material 13 to provide z. B. from the sensor array 14 detected metal parts 13 ' additionally z. B. optically detect the exhaust nozzles 24 time to control even more precise.

2a and 2 B show in a schematic representation of the operation of one of an excitation coil 102 and two oppositely wound detector coils 104 . 106 existing sensor 100 , In the example shown, all coils 102 . 104 . 106 two windings on. The number of turns can be chosen differently, however, with the detector coils 104 and 106 should have the same number of turns. Not shown are the electrical lines through which these coils 102 . 104 . 106 be energized. The the coils 102 . 104 . 106 associated contact surfaces are denoted by the reference numerals 112 . 114 and 116 designated.

The two detector coils 104 and 106 are concentric with the exciter coil as a coil pair 102 surrounded, which serves to generate an alternating field. Through this alternating field are in metal parts 15A . 15B . 15C Magnetic fields induced in the effective range of the alternating field and the sensor 100 enter. The exciter coil 102 For this purpose, it is acted upon by a high-frequency alternating voltage, so it generates an electromagnetic alternating field with the same frequency. Typical frequencies can be z. B. in the kHz range. Frequency mixtures can also be used.

Fördergutteile 13 from a non-conductive material show no interaction with the alternating field. In contrast, in conductive conveyed parts 15A . 15B and 15C induced an alternating electromagnetic field according to typical, material-corresponding transfer function.

The two detector coils 104 and 106 are mirror-symmetric to a mirror plane 115 arranged. This mirror plane 115 is at an angle to the direction of movement 116 the conveyed goods 15A . 15B . 15C , In the example shown, the distance between the direction of movement is 116 and the mirror plane 115 included angles 45 °. The centroid M of the detector coil 104 and the area center of gravity M 'of the detector coil 106 are connected by an imaginary connecting line L, which is oriented perpendicular to the mirror plane due to the 45 ° inclination.

In 2 B are three waveforms A, B, C of the sensor 100 supplied signal to the three metal parts 15A . 15B . 15C shown, these three parts of the sensor 100 happen in different places. part 15A crosses the sensor 100 centered while the parts 15B and 15C the sensor 100 cross further outside, in the case of part 15C me still on the outer edge.

If you follow the trajectory 116 of the part 15A , so it first crosses the direction of movement 116 further upstream detector coil 104 , As from the upper waveform A of the 2 B As can be seen, this leads to an increase in the signal, that is, the differential phase voltage which can be measured with phase difference between the two detector coils 104 and 106 increases, because in the direction of movement 116 further behind the detector coil 106 not yet of that in metal part 15A induced alternating field is affected. Without limiting the generality, it is assumed that the detector coil 104 provides a positive signal component while detector coil 106 provides a negative signal component. Under this assumption, the total signal A increases as soon as the metal part 15A in the detection area of the detector coil 104 penetrates. The signal A then reaches a constant value and then falls after a certain time, that of the duration of the crossing of the detector coil 104 corresponds, again, to after a zero crossing, the crossing of the plane of symmetry 115 through the metal part 15A corresponds to go into the negative area. Here dominates the negative signal of the detector coil 106 , After leaving the effective range of the detector coil 106 the signal A falls back to zero.

The to the metal parts 15B and 15C shown signal curves B and C arise from the same considerations. metal part 15B reached in time a little later than part 15A the sphere of influence of the detector coil 104 , The crossing time for detector coil 104 is also shorter than for metal part 15A , and the plane of symmetry 115 is reached earlier, so that the zero crossing occurs earlier in time. The negative part of the total signal B is longer in time because the metal part 15B a longer way across the detector coil 106 has to cover. After metal particles 15B also the second detector coil 106 has completely crossed, here again the signal B falls back to zero, with metal part 15B leaves the sensor area in a shorter time than metal part 15A , Therefore, signal B is also shorter in time than signal A.

For metal part 15C the special case is that the detector coil 104 not crossed at all. Therefore, the signal curve labeled B does not show a positive total signal component. It is therefore missing at a zero crossing. Once metal part 15C the detector coil 106 reached, the total signal goes into the negative signal range. The metal part 15C leaves detector coil after a relatively short time 106 , so that the negative total signal duration is shorter than that of the metal parts 15A and 15B shown signal curves A and B.

The parallel to the direction of movement 116 shown dashed lines correspond to positions of the sensor 100 associated exhaust nozzles 24 , in the 1 were shown. About the width of the sensor 100 distributed are seven of these exhaust nozzles 24 , where the two outermost lying partially this sensor 100 are assigned, but sometimes also the left or right neighbor sensor.

3 shows a block diagram of a possible wiring of a sensor 100 , where the circuit is only exemplary in nature and in particular when using multiple sensors 100 Deviating trained looks like. It can then z. As ADC chains or multiplexers, a row logic and parallel computers are used. The architecture of the evaluation electronics is largely freely selectable and unaffected by the sensor structure. Such circuits are also generally known in the art, so it is not discussed further below.

The controller could z. B. via a conventional computer with suitable interfaces for communication with the sensor 100 , the angle encoder 27 and the exhaust nozzles 24 respectively. However, the data volumes generated by the sensors will be so significant that computers and interfaces will reach their performance limits. In the example shown here is the control, supply and signal evaluation of the sensor 100 therefore from an integrated powerful microcontroller (μC) 302 accepted. This microcontroller 302 can also control the exhaust nozzles 24 We have an interface and a bus line 303 with the valves to be switched 26 in connection. But a microcontroller solution is only one of several possibilities.

The exciter coil 102 is powered by a power amplifier 305 applied with a suitable high-frequency AC voltage to produce an alternating field. It can also be given a frequency-mixed AC voltage to the exciter coil. The power amplifier 305 again powered by an upstream digital-to-analogue converter (DAC) 307 which in turn is from the microcontroller 302 is controlled.

On the signal side, this will be on the detector coils 104 and 106 tappable AC signal in a measuring amplifier 309 fed, which is designed as a differential amplifier, and an analog alternating signal to an analog-to-digital converter (ADC) 311 supplies, over which the signal of the measuring amplifier 309 turn back to the microcontroller 302 arrives. There or in another computer device, the signal z. B. as above 2 B described evaluated.

The tasks of the microcontroller 302 By appropriate training also on the evaluation and overall control of the sorting device 10 expand, and z. B. as digital hardware and firmware in the sensor device 14 be integrated. Because of the parallel requirement of the same real-time mathematics for the multiple sensors 100 and the data streams generated thereby, the use of parallel computing and digital signal processors is beneficial.

4 shows in plan view a section of a sensor device 14 with two rows of sensors 100 that the in 2a correspond to the embodiment shown. There are these sensors 100 in groups on a board 402 arranged. Without restriction of generality z. B. five sensors each 100 per board 402 be provided.

The sensors 100 stand within the lines at equal intervals, the sensors 100 the one line stand on gap to the sensors 100 the other line. All sensors 100 show the same inclination of the plane of symmetry 115 relative to the direction of movement 116 , which here corresponds to the direction of the dotted lines, which, as already in 2a , the local arrangement of the exhaust nozzles V1-V20 ( 24 ), which in dependence of the sensor signals for blowing out a detected metal part 15 be controlled.

The distances between the sensors 100 within a row are smaller than the diameter of the detector coils 104 . 106 so that there is an overlap in width due to the staggered th arrangement of the two rows. A metal part, the z. B. along that trajectory that can be assigned to the purge valve V5, passes over both sensor 100 ' as well as sensor 100 '' , In the evaluation of the sensor signals of these two sensors, the evaluation and control device 20 So z. B. make an adjustment to the effect whether the detection of a metal part by sensor 100 ' at a certain location coincides with the time-offset detection message of the sensor 100 '' , Furthermore, in such an arrangement, a plausibility check can be performed on parts that are wider than the valve spacing. So z. B. a part that covers the valve line V1 and V2, are calculated in its contour: the first sensor 100 The upper line responds with the same positive and negative signal time. The sweeping at the level of line V2 could be from the first sensor 100 not be measured. But there the first sensor 100 '' If the bottom line reacts now and only with a positive signal, the part along the lines V1 and V2 must be the sensors 100 and 100 '' have crossed. Is the part even bigger, so it passes the sensors 100 and 100 '' z. B. along the lines V1, V2 and V3, so the first sensor reacts 100 '' the bottom line with a long positive signal and a short negative. It can therefore be concluded that the sensors have been swept over the width of the lines V1, V2 and V3. It can be interpolated according to this principle, almost every conceivable part width, which is larger than the sensors themselves.

The sensor device according to the invention 10 allows high-resolution location of electromagnetically detectable parts, via the sensor device 14 be moved away. By suitable evaluation of the sensor signals, z. B. by the signals of several adjacent sensors or even all sensors and by adding interpolation according to the just described principle, a complete image of the detected parts can be obtained. The sensor device shown by way of example 14 works reliably for a very wide range of sizes of the parts to be detected, ie both for parts smaller than the diameter of the sensors 100 are, as well as parts that have multiple sensors 100 run away at the same time.

The after 4 resulting improvement of the resolution over the generic state of the art by a factor of 5 is already achieved by simple means. When using more computing and evaluation power, and possibly also when using other sensors, the resolution can be further refined without much effort. Resolution increases by a factor of 10 were easily achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0353457 B1 [0004]

Claims (20)

Sensor device ( 14 ) with several sensors ( 100 ) for detecting electromagnetically detectable items to be conveyed ( 15 . 16 ), with an associated conveyed material ( 13 ) in a conveying plane and in a direction of movement ( 116 ) on the sensors ( 100 ) passing conveyor ( 12 ), with a facility ( 102 ) for generating an electromagnetic alternating field, wherein the sensors ( 100 ) each have a pair of detector coils ( 104 . 106 ), which are connected to an evaluation device ( 20 ) for determining a difference signal between the coils ( 104 . 106 ) of a pair are connected for detecting conveyed goods ( 15 ), which deform due to their material properties, the alternating field, characterized in that the two detector coils ( 104 . 106 ) of the pair are arranged so that they have parallel to the conveying plane standing cross-sectional areas with mutually shifted centroids (M, M '), wherein the two detector coils ( 104 . 106 ) of the pair D-shaped and spaced from each other mirror-symmetrical to a plane of symmetry ( 115 ), which are not simultaneously a mirror plane of each of the detector coils ( 104 . 106 ), wherein the connecting line (L) between the centroids (M, M ') and the plane of symmetry ( 115 ) obliquely to the direction of movement ( 116 ) of the conveyed goods ( 13 ) stands. Sensor device ( 14 ) according to claim 1, characterized in that the sensors ( 100 ) are arranged in a row which is substantially perpendicular to the direction of movement ( 116 ) of the conveyed goods ( 13 ) stands. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the device for generating the alternating field has a plurality of exciter coils ( 102 ) and each sensor ( 100 ) an exciter coil ( 106 ) assigned. Sensor device ( 14 ) according to claim 3, characterized in that the sensor coils ( 104 . 106 ) from the associated exciter coil ( 102 ) are surrounded. Sensor device ( 14 ) according to one of claims 3 or 4, characterized in that the exciter coils ( 102 ) are circular wound coils. Sensor device ( 14 ) according to one of the preceding claims, characterized in that all excitation and detector coils ( 102 . 104 . 106 ) substantially in the same plane parallel to the conveying plane of the conveyed material stream ( 13 ) are arranged. Sensor device ( 14 ) according to claim 6, characterized in that a plurality of sensors ( 100 ) on a fine conductor board ( 402 ) are arranged. Sensor device ( 14 ) according to one of the preceding claims, characterized in that all excitation coils ( 102 ) are operated synchronously. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the sensors ( 100 ' . 100 '' ) are arranged in several staggered rows. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the detector coils ( 104 . 106 ) and / or the exciter coils ( 102 ) one to Fördergutstrom ( 13 ) have an open core. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the sensors lying in one line ( 100 ) are arranged equidistantly. Sensor device ( 14 ) according to one of the preceding claims, characterized in that at the line ends sensor-empty exciter coils ( 102 ) are arranged. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the angle between the direction of movement ( 116 ) of the conveyed stream ( 13 ) and the connecting line of the centroids or the symmetry plane ( 115 ) of the detector coils ( 104 . 106 ) of a pair between 30 ° and 60 °. Sensor device ( 14 ) according to claim 13, characterized in that the angle is 45 °. Sensor device ( 14 ) according to one of the preceding claims, characterized in that the evaluation device ( 20 ) is formed, the signals of a plurality of adjacently arranged sensors ( 100 ) evaluate correlated in time. Sensor device according to one of the preceding claims, characterized in that the device ( 102 ) is designed to generate an alternating electromagnetic field for generating a multi-frequency alternating field. Contraption ( 10 ) for the automated sorting out of electromagnetically detectable fractions from a conveyed material stream ( 13 ), with a conveyor ( 12 ) for moving the conveyed material ( 13 ) by a detection area, with a in the De arranged detection area ( 14 ) for detecting electromagnetically detectable items to be conveyed ( 15 ) in a transverse to the sensor device ( 14 ) on this adjacent moved Fördergutstrom ( 13 ), with a separating device ( 24 ) for selectively separating a detected and sorted fraction ( 15 ' . 15 '' ), and with an evaluation and control device ( 20 ), which the separating device ( 24 ) based on the evaluation of the sensor device ( 14 ) supplied results, characterized by a sensor device ( 14 ) according to any one of the preceding claims. Contraption ( 10 ) according to claim 17, characterized in that the separating device comprises a plurality of outlet nozzles ( 24 ) having. Apparatus according to claim 17 or 18, characterized in that the conveyor device is a conveyor belt ( 12 ), and the sensors ( 100 ) below the conveyor belt ( 12 ) are arranged. Apparatus according to claim 19, characterized in that a measuring device ( 29 ) the instantaneous transport speed of the conveyor belt ( 12 ) and this measurement for correcting the delay time between detection of the conveyed material part ( 13 ) and driving the separating device ( 24 ) is used.