Capacitive sensor device for bulk material metering device

Abstract

The invention relates to a capacitive sensor device (17) for a bulk material metering device, which determines the mass of a metering quantity (2) produced by means of the bulk material metering device. The sensor device (17) has at least one sensor unit (42) comprising a first electrode (11), a second electrode (12) and an insert (13) positioned between the two electrodes (11, 12). A measuring channel (10) extending in the vertical direction (z) is formed in the insert (13). A tensioning device (14) acting on the associated electrode (11, 12) in the horizontal direction (y) is arranged on the side of at least one electrode (11, 12) facing away from the insert (13). In the released state of the tensioning device (14), the at least two electrodes (11, 12) and the insert (13) therebetween can be displaced in the horizontal direction. A plurality of sensor units (42) are arranged in a row extending in a horizontal direction (y), wherein in each case one tensioning device (14) is arranged between the sensor units (42).

Description

Technical Field

[0001] The invention relates to a capacitive sensor device for a bulk material metering device, which serves to determine the quality of a metered quantity produced by means of the bulk material metering device. Background Art

[0002] For example, in the pharmaceutical sector, but also in the sector of nutritional supplements, etc., bulk materials are processed into the form of powders, pellets or microtablets, which have to be provided in precisely measured portion quantities or metered quantities for the intended dosage form. A target container, for example in the form of a blister, a plug-in capsule, etc., is filled with this measured metered quantity of this bulk material so that the consumer can take the corresponding unit dose and consume it.

[0003] This bulk material is transferred to the so-called roller dosing device, siphon, etc. into the individually measured dosing amount, which is then filled into the respectively associated target container. The roller dosing device considered as an example here comprises a dosing roller, which is provided with at least one, usually a plurality of dosing openings on the circumferential side, wherein the dosing openings are delimited on the inside by means of a filter element and negative pressure can be applied through the filter element. Under the effect of negative pressure, the powder is sucked into the dosing opening, wherein a dosing amount of powder is formed, the volume of which corresponds to the volume of the corresponding dosing opening. The dosing amount formed in this way is then ejected from the dosing opening by means of overpressure and forwarded to the target container.

[0004] It is clear from the previous embodiments that the metering performed by means of the bulk material metering device used as the basis here is volumetric metering. However, in the usual case, a metering is sought in which the measured metered quantity has a certain mass within the permitted tolerance range. For volumetric metering, it is therefore important to obtain a relationship that is as reproducible as possible between the measured volume and the weight actually achieved in the process.

[0005] In order to check the actually achieved dosing accuracy, so-called "Advanced Quality Verification" (AMV) systems are increasingly being used, in which a capacitive measuring device is used. The capacitive measuring device comprises two electrodes arranged on both sides of a measuring path, between which a capacitive field is formed. The dosing quantity blown out of the dosing opening falls through the capacitive measuring path and here, due to its dielectric properties, produces a field change, which results in a capacitive measuring signal. In the case of correct calibration, the measuring signal provides conclusions about the quality of the dosing quantity and allows the dosing process to be controlled randomly or even 100%.

[0006] To form the measuring path, an insert made of plastic is used in which a continuous measuring channel is formed. Such an insert includes, but is not limited to, enabling an optimal, reproducible and largely parallel arrangement of the two electrodes relative to one another and also relative to the actual measuring path.

[0007] The difficulty that arises in practice is to press the electrodes as flatly as possible onto the outside of the insert. Another difficulty is the lateral positioning of a plurality of inserts arranged in a row. The inserts must be kept at a certain distance from one another in order to be aligned precisely with the individual drop paths of a plurality of metered quantities that are already discharged simultaneously from a row of metering openings. To achieve this, the electrodes are fastened in sensors known to date via matching pieces. The width of the matching piece is brought to the correct size via an inserted foil. This process is very complex. Furthermore, it is not possible to pre-tension the electrodes. Summary of the invention

[0008] The invention is based on the object of specifying a capacitive sensor arrangement which can be adjusted simply and precisely.

[0009] The object is achieved by a capacitive sensor device for a bulk material metering device, the capacitive sensor device being used to determine the quality of a metered amount produced by means of the bulk material metering device, the sensor device having at least one sensor unit, the sensor unit comprising a first electrode, a second electrode and an insert positioned between the two electrodes, wherein a measuring channel extending in a vertical direction is formed in the insert, wherein a tensioning device acting on the relevant electrodes in a horizontal direction is arranged on a side of at least one electrode facing away from the insert, wherein in a state where the tensioning device is loosened, at least two electrodes and the insert located therebetween can be displaced in a horizontal direction, wherein a plurality of sensor units are arranged in a row extending in a horizontal direction, wherein a tensioning device is each arranged between the sensor units.

[0010] According to the present invention, a capacitive sensor device having at least one sensor unit is provided, wherein the sensor unit comprises a first electrode, a second electrode and an insert positioned between the two electrodes, wherein a measuring channel extending in a vertical direction is formed in the insert, wherein a tensioning device acting on the relevant electrodes in a horizontal direction is arranged on a side of at least one electrode facing away from the insert, and wherein at least two electrodes and the insert located therebetween are displaceable in a horizontal direction when the tensioning device is released.

[0011] The displaceability of the electrodes and the insert allows precise positioning at the desired location. By tightening the tensioning device, two functions are performed at once. On the one hand, the two electrodes and the insert located therebetween are pressed into a stack, wherein the electrodes are pressed against the outside of the insert with precise orientation and by means of pretensioning. On the other hand, the unit consisting of electrodes and insert pressed in this way is securely fastened in its selected position. Assembly time and assembly expenditure are reduced to a minimum. The replacement of the mentioned unit in the event of damage or when changing the format can be carried out with little effort.

[0012] In a simple basic embodiment of the invention, it is sufficient to arrange a separate clamping element only on one side of only one electrode, while a fixed stop, for example, is positioned on the opposite side. In an advantageous development, a clamping device is arranged on each side of the two electrodes facing away from the insert, which acts on the relevant electrode in the horizontal direction. By tightening the two clamping devices against each other, it is possible not only to clamp the electrode to the insert, but also to perform a sensitive and precise lateral position adjustment of the clamped structural unit.

[0013] According to the invention, a plurality of sensor units are arranged in a row extending in the horizontal direction, wherein a tensioning device is arranged between the sensor units. Advantageously, a plurality of and in particular all tensioning devices can be displaced in the horizontal direction in the loosened state. By screwing on all tensioning devices in sequence, all components that are not yet displaceable can be positioned with precise orientation in the horizontal direction and then secured in the position they have found. The spacing between each other can be adjusted while compensating for even rough tolerances. At the same time, the electrodes are pressed with precise orientation onto the outside of the insert so that they are precisely aligned with the measuring channel or with the measuring path in order to achieve the desired measuring accuracy. Overall, a high orientation accuracy and thus a high quality in terms of measuring accuracy are achieved with a short assembly time. In addition, a modular system is created which can be adapted in a simple manner with respect to the number of channels or the number of measuring paths and also with respect to the format used.

[0014] Different design solutions are contemplated for the specific design of the tensioning device. In a suitable embodiment, the tensioning device comprises a first tensioning element, a second tensioning element and a tensioning screw, which tensions the two tensioning elements against each other, wherein a sliding slope is formed at at least one of the two tensioning elements and in particular at both tensioning elements, which slides in contact with the other tensioning element. Advantageously, the two tensioning elements are designed as identical components, each with a sliding slope. This design is structurally simple and cost-effective. The design reliably maintains the adjusted position and the applied tensioning force. In addition, a large tensioning path can be realized, so that the position of the unit composed of electrode and insert can be adapted over a large available adjustment path. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The embodiments of the present invention are described in more detail below with reference to the accompanying drawings.

[0016] Figure 1 A schematic cross-sectional view of a bulk material metering device is shown using the example of a roller metering device with a product supply, the bulk material metering device having a metering roller and a capacitive sensor device for determining the quality of the individual metered quantities.

[0017] Figure 2 A schematic exploded view of a part of a tensioning device of a capacitive sensor arrangement is shown, which is used as a Figure 1 A part of a measuring device having two tensioning elements, a tensioning screw and a nut,

[0018] Figure 3 Show according to Figure 1 and 2 A schematic longitudinal section of the measuring device in the untensioned state, and

[0019] Figure 4 Displays the basis for the tensioned, operationally ready control state Figure 3 device. DETAILED DESCRIPTION

[0020] Figure 1 A schematic cross-sectional view of a bulk material dosing device is shown using a roller dosing device 3 as an example when producing individual dosing quantities 2 of bulk material and for transferring such individual dosing quantities 2 into a target container 21. Instead of the roller dosing device 3, a sliding dosing device, a siphon or any other suitable configuration of a bulk material dosing device can also be provided. The bulk material to be dosed is a powdered product 1, i.e., a pharmaceutical powder. However, it can also be a nutritional supplement, etc. Instead of the powdered product 1, pellets, microtablets or other bulk materials are also considered. Here, the target container 21 is a schematically indicated blister, which is also encapsulated by means of a covering film after filling. However, insertable capsules or other containers are also considered as target containers 21.

[0021] The roller metering device 3 comprises a product supply 4, a metering roller 5 and a capacitive measuring device 6. The capacitive measuring device 6 is also referred to as an "Advanced Quality Verification System" or AMV system. In the funnel-shaped product supply 4, a powdery product 1 is held ready for measurement. With the aid of the metering roller 5, a partial amount of the powdery product 1 is removed from the product supply 4 and a metered quantity 2 of precisely defined volume is formed therefrom. The quality of individual, in particular all, metered quantities 2 is subsequently determined with the aid of the capacitive measuring device 6.

[0022] The metering roller 5 extends along the longitudinal axis and is substantially cylindrically formed relative to the longitudinal axis. The metering roller has at least one metering opening 7 on the circumferential side. In the preferred embodiment shown, the metering roller 5 is provided with a plurality of metering openings 7. Although the cross-sectional view shown here cannot be identified, two or three to twelve metering openings 7 each form an opening row, which extends parallel to the axis of rotation 19. Four such opening rows are positioned at equal angular spacings along the circumferential direction around the axis of rotation 19, i.e., positioned at 90° to each other. Here, one, i.e., a total of four metering openings 7 can be identified from the mentioned opening rows. However, in the axial direction and / or circumferential direction, different numbers of metering openings 7 or opening rows can also be advantageous.

[0023] The metering opening 7 is open radially outward and is delimited radially inward by a filter element 8. Between the outer side 22 of the metering roller 5 and the radially inner filter element 8, the metering opening 7 has a defined, preset volume. The filter element 8 is air-permeable, but not impermeable to bulk material, i.e., impermeable to the powdery product 1 in this case. If necessary, the metering opening 7 can be charged with negative pressure from a negative pressure source 15 or overpressure from an overpressure source 16 through the corresponding filter element 8 - in a manner controlled by the control device 18.

[0024] The metering roller 5 is rotatably supported around the rotation axis 19 in the direction of the arrow 20 and is provided with a corresponding rotary drive not shown here. During operation, the metering roller rotates in a clocked manner, wherein each metering opening 7 stays in the filling position I at the top in the direction of gravity and the discharge position III at the bottom in the direction of gravity in at least two clock cycles. Instead of clocked movement, continuous rotation can also be advantageous. In the illustrated embodiment, each metering opening 7 traverses four different positions in four clock cycles, starting with the filling position I at the top, followed by the first intermediate position II. Thereafter, before the cycle starts again at the upper filling position I, it is the lower discharge position III and the second intermediate position IV.

[0025] In the upper filling position I, the corresponding metering opening 7 is filled with the powdered product 1 from the product reserve 4 to form the metered amount 2. For this purpose, the metering opening 7 is loaded with a negative pressure from a negative pressure source 15. The negative pressure sucks the powdered product 1 from the product reserve 4 into the metering opening 7. As a result, a metered amount 2 of the powdered product 1 is formed, which completely fills the metering opening 7 and whose volume corresponds to the volume of the metering opening 7. In the subsequent first intermediate position II, a filling level check can optionally be performed. In the lower discharge position III, the metering opening 7 is loaded with an overpressure from an overpressure source 16, whereby the metered amount 2 is discharged from the metering opening 7 and delivered to the corresponding target container 21. The now empty metering opening 7 is moved further to the second intermediate position IV and can be optionally cleaned there, for example by blowing.

[0026] Part of the capacitive measuring device 6 mentioned above for determining the mass of each metered quantity 2 is a capacitive sensor device 17, which is also connected to a control device 18 and has two electrodes 11, 12 spaced apart from each other. The measurement data of the capacitive sensor 17 are detected and evaluated in the control device 18, which generally leads to the formation of the measuring device 6. The metered quantity 2 discharged from the metering opening 7 in the lower discharge position III falls into the target container 21 along the vertical direction z through the electrodes 11, 12 of the capacitive sensor device 17 with gravity. From the field changes that take place in the capacitive sensor device 17, the mass of the metered quantity 2 that passes through is determined according to the AMV system. Although it is not mandatory to determine the weight of each individually dosed metered quantity 2. On the contrary, it is sufficient to repeat the individual mass determinations randomly only after several metering cycles. However, the mass determination is preferably performed at 100% of the measured metered quantity 2.

[0027] Figure 2 The tensioning device 14 ( Figure 3 , 4 ) is a schematic exploded view of a portion of Figure 1 3. Part of a measuring device 6 of FIG. 1, wherein the tensioning device has two tensioning elements 31, 32, a tensioning screw 33 and a nut 34. Instead of the nut 34, a threaded bore or a bore for accommodating a self-tapping thread in the housing of the sensor device can also be advantageous. Here, all components are shown in their installed orientation relative to the vertical direction z ( Figure 1 , 3 , 4). The tensioning screw 33 has an external thread and is aligned in the vertical direction z, wherein the nut 34 is also aligned with its internal thread correspondingly.

[0028] The first tensioning element 31 is provided with a planar sliding bevel 35 which here forms an angle of 45° with respect to the vertical direction z. However, different angles, in particular in the range of 30° to 60°, may also be advantageous. In the region of the sliding bevel 35, the first tensioning element 31 is penetrated by an elongated hole 36, the hole axis 37 of which is parallel to the vertical direction z and the wide cross-sectional axis of which extends parallel to the horizontal direction y.

[0029] The two tensioning elements 31, 32 are designed as identical parts, each with a sliding ramp 35. In other words, the second tensioning element 32 is designed identically to the first tensioning element 31. What has been said above for the first tensioning element 31 applies in an analogous manner to the structural features of the second tensioning element 32. However, the second tensioning element is rotated 180° about an axis extending in the horizontal direction y, so that the sliding ramps 35 of the two tensioning elements 31, 32 face each other in the assembled state.

[0030] Figure 3 Show according to Figure 1 and Figure 2 A schematic longitudinal section of a capacitive sensor device 17 in an untensioned state. Figure 3 The cross section of the view is parallel to the rotation axis 19 ( Figure 1 ) stretches in the horizontal direction y and stretches in the vertical direction z along the direction of gravity.

[0031] According to the invention, the sensor device 17 has at least one, here a plurality of sensor units 42. A single sensor unit 42 comprises a first electrode 11, a second electrode 12 and an insert 13 positioned between the two electrodes 11, 12. In other words, with respect to the horizontal direction y, the first electrode 11 is located on one side of the respective insert 13 and the second electrode 12 is located on the opposite side of the respective insert 13. The pair of first and second electrodes 11, 12 together form a capacitor. The capacitor is connected to the control device 18 ( Figure 1 ) are interconnected to form the capacitive measuring device 6 mentioned above. The insert 13 is made of plastic with suitable dielectric properties and is in the field of the corresponding capacitor. In each insert 13, a measuring channel 10 extending in the vertical direction z and passing from top to bottom is formed.

[0032] According to the invention, a tensioning device 14 is arranged on the side of at least one of the two electrodes 11, 12 of the sensor unit 42 facing away from the insert 13, said tensioning device acting on the relevant electrode 11, 12 in the horizontal direction y. Figure 3 In the exemplary embodiment of , such a tensioning device 14 is arranged on the respective side of the two electrodes 11 , 12 of each sensor unit 42 facing away from the insert 13 . Figure 3It can be seen that a plurality of sensor units 42 are arranged in a row extending in the horizontal direction y, wherein a tensioning device 14 is arranged between the sensor units 42. The tensioning devices 14 located in between thus act on both sides, i.e. on one side on one electrode 11 of a particular sensor unit 42 and on the other side also on the other side of the respective adjacent sensor unit 42. The number of inserts 13 in which the measuring channels 10 are formed corresponds to the number described above in conjunction with Figure 1 The number of metering openings 7 of the described opening row extending parallel to the axis of rotation or parallel to the horizontal direction y. Thus, in the illustrated embodiment, there are two or three to twelve inserts 13 which have measuring channels 10 formed therein, wherein each measuring channel 10 is assigned to each metering opening 7 of the relevant opening row.

[0033] The tensioning device 14 according to the invention has essentially the following structure: the tensioning process causes the corresponding tensioning device to widen in the horizontal direction y. Figure 2 , 3 In the embodiment of the present invention, two tensioning elements 31, 32 are stacked in pairs with their flat and planar sliding slopes 35, wherein the elongated holes 36 of the tensioning elements at least partially overlap, and wherein the tensioning screw 33 is guided through the elongated holes 36 of the two tensioning elements 31, 32 and screwed into the nut 34. Despite the guiding of the tensioning screw 33 through, the elongated hole 36 still allows the two tensioning elements 31, 32 to be displaced relative to each other in the horizontal direction y.

[0034] according to Figure 3 , the tensioning device 14 has not yet been tightened or tensioned. In the vertical direction z, the tensioning device is located on the upper base plate 38 and is only shown for a better overview. Figure 4 The base plate 38 and the matching plate 40 are both provided with a row of openings 39, 41, the number and spacing of the openings corresponding to the number and spacing of the metering openings 7 in the row of openings ( Figure 1 ). Figure 3In the released state of the tensioning devices 14, the electrodes 11, 12 and the inserts 13 of all sensor units 42 can be displaced in the horizontal direction y, which is graphically expressed by the horizontal spacing of the mentioned components from one another. In the released state shown, the tensioning devices 14 can also all be displaced in the horizontal direction y. Fixed stops, not shown, are distributed at the two lateral ends of the row of sensor units 42, wherein the respectively outermost tensioning devices 14 can be supported relative to the stops. However, it can also be advantageous if one or both stops are replaced by a tensioning device 14 that is fixed in the horizontal direction y, i.e. cannot be displaced. In this case, then, all the remaining tensioning devices 14, i.e. all tensioning devices 14 except one or two, can be displaced in the horizontal direction y.

[0035] The respective tensioning device 14 is tensioned by tightening the tensioning screw 33, which presses the pair of tensioning elements 31, 32 against each other in the vertical direction z. In this case, the sliding ramp causes the tensioning elements 31, 32 to move apart in the horizontal direction y and overall causes a lateral widening of the tensioning device 14. The lateral widening causes the tensioning device 14 to laterally abut against adjacent electrodes 11, 12 and to press them against the outer side of the respective insert 13.

[0036] Figure 4 Show according to Figure 3 A device having such a tensioning device 14 for tensioning. The tensioning of the tensioning device has a number of effects according to the invention. On the one hand, the electrodes 11, 12 are pressed flat against the outside of the respective insert 13 so that the electrodes 11, 12 are precisely aligned with the respective measuring channels 10 in the insert 13. On the other hand, by means of the coordinated tensioning of the tensioning device, the lateral positioning of the individual sensor units 42 relative to each other and also relative to the openings 39, 41 or the drop track of the individual metering quantities 2 can be performed. Thus, the spacing and position of the sensor units 42 can be precisely adjusted and fastened so that, according to Figure 4 The individual metered quantity 2 falls centrally through the measuring channel 10 and generates an exactly reproducible capacitive measurement signal here by means of the exactly aligned electrodes 11 , 12 .

[0037] The entire capacitive sensor device can be disassembled by loosening the tensioning screw 33. The insert 13 or also the entire sensor unit 42 can be easily replaced and assembled together in a modular manner in the same or any different number.

Claims

1. A capacitive sensor device (17) for a bulk material dosing device, the capacitive sensor device being used to determine the quality of a dosing quantity (2) produced by means of the bulk material dosing device, the capacitive sensor device comprising at least one sensor unit (42), the sensor unit comprising a first electrode (11), a second electrode (12) and an insert (13) positioned between the two electrodes (11, 12), wherein a measuring channel (10) extending in a vertical direction (z) is formed in the insert (13), wherein in a water A tensioning device (14) acting on the relevant electrodes (11, 12) in a horizontal direction (y) is arranged on a side of at least one electrode (11, 12) facing away from the insert (13), wherein when the tensioning device (14) is loosened, at least the two electrodes (11, 12) and the insert (13) located therebetween can be displaced in a horizontal direction, wherein a plurality of sensor units (42) are arranged in a row extending in the horizontal direction (y), wherein each tensioning device (14) is arranged between the sensor units (42).

2. The sensor device according to claim 1, It is characterized in that On the respective side of the two electrodes (11, 12) facing away from the insert (13), a tensioning device (14) is arranged, which acts on the relevant electrode (11, 12) in the horizontal direction (y).

3. The sensor device according to claim 1, It is characterized in that A plurality of tensioning devices (14) are displaceable along the horizontal direction (y) in a released state.

4. The sensor device according to claim 1, It is characterized in that All tensioning devices (14) are displaceable in the horizontal direction (y) in a released state.

5. The sensor device according to claim 1, It is characterized in that The tensioning device (14) comprises a first tensioning element (31), a second tensioning element (32) and a tensioning screw (33), wherein the tensioning screw tensions the two tensioning elements (31, 32) to each other, wherein a sliding inclined surface (35) is formed at at least one of the two tensioning elements (31, 32) for contacting the other tensioning element (32, 31).

6. The sensor device according to claim 5, It is characterized in that Sliding inclined surfaces (35) which are in contact with the other tensioning element (32, 31) are formed on the two tensioning elements (31, 32).

7. The sensor device according to claim 5, It is characterized in that The two tensioning elements (31, 32) are designed as identical parts each having a sliding ramp (35).

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