METERING DEVICE FOR TABLETS AND METHOD FOR METERING TABLETS

Abstract

The application relates to a metering device for tablets, in particular for micro tablets, as well as to an associated metering method. The metering device includes a fixed device part and a metering element which rotates in a plane of rotation having several tablet receiving elements. The plane of rotation lies at an angle of inclination of no more than 30° with respect to the weight force direction. The tablet receiving elements are open in at least one lateral direction with reference to the rotating plane. The fixed device part includes a feeder surface for the tablets which, with reference to the weight force direction, is arranged in the bottom region of metering element and at the side next to metering element, wherein the feeder surface borders on the metering element by way of a lead-in edge at the level of the tablet receiving elements.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is based upon and claims the benefit of priority from prior European Patent Application No. 14 000 630.5, filed Feb. 22, 2014, the entire contents of which are incorporated herein by reference in their entirety.

BACKGROUND

The application relates to a metering device for tablets, in particular for micro tablets as well as to a method for metering tablets.

Under certain conditions, it is necessary not to prepack ready compressed tablets individually for example in blister packs, but to meter them in a certain quantity which must be precisely adhered to. Said requirement occurs in particular in the case of so-called micro tablets with a diameter of less than 3.0 mm. These are provided to be taken in a measured quantity and are consequently filled, for example, into two-piece capsules in a suitable quantity as an individual dose.

In the case of metering tablets which are provided as bulk goods, a series of requirements should be taken into consideration. On the one hand, it must be ensured that precisely the provided number of individual tablets passes into the target container in order to avoid overdosing or underdosing. On the other hand, the metering has to be effected in a manner that protects the material so that no tablets are broken. The device and the method must be insensitive to the barely avoidable presence of fragments and tablet dust. Basic economic conditions dictate a high cycle or output rate. Over and above this, the arrangement provided for the metering can only take up a small installation space so that it can be incorporated into a filling system.

Different designs of metering devices for tablets are known. A rotating drum with a horizontal rotational axis which is filled by way of a tablet store is provided in one realization. On the inside the circumferential wall of the drum comprises tablet receiving elements into which individual tablets are fitted. As a result of rotating the drum, the tablets, separated into singles, are conveyed out of the tablet store, ejected in a corresponding number and supplied to the target container.

One known alternative includes providing a rotating disk with an inclined rotational axis, wherein corresponding tablet receiving means are installed on the top surface of the rotating disk. In this connection, the tablet store is poured onto the rotating disk, as a result of which the separating out into singles or the metering operation is performed in an analogous manner to the drum version.

But various problems arise when such embodiments are used in practice. Depending on the processing state and in particular in the case of a corresponding coating, the tablets tend to stick to one another, as a result of which duplicates and triplicates can be realized. These cannot be entrained by the tablet receiving elements, which are adapted in form and volume to the individual tablets, or can only be entrained in a limited manner. Consequently, it is difficult to obtain the precise quantity of tablets for an individual dose.

It is also problematic that the tablet store, which is located in the drum or on the disk, is set into movement and is intermixed as a result of the rotation. The tablets rub against one another and also against their moved support, which results in broken tablets, or at least in considerable development of dust. The tablets can lose their size as per specification as a result. Tablet fragments and dust can be removed from the tablet store only at great effort—if at all. Tablet fragments which pass into the tablet receiving elements do not meet the metering objective on the one hand, but prevent, on the other hand, tablets as per specification passing into the corresponding tablet receiving elements. All in all it is difficult to ensure that each tablet receiving element has received one tablet each and that, as a result, the desired number of tablets as per specification can be transferred into the target container.

In known embodiments, it is certainly possible to monitor the tablet receiving elements using cameras and image evaluation to the effect that all the tablet receiving elements are filled correctly with one tablet each. In the event of trouble spots, however, underdosing has to be accepted, as a result of which the associated target container has to be eliminated as waste.

SUMMARY OF PREFERRED EMBODIMENTS

It is one object of the application to provide a metering device for tablets, which device meters tablets in a manner which protects the material, is highly reliable and has a high pulse rate according to quantity. This and other objectives are achieved by embodiments of this application.

In addition, it is another object of the application to provide a method for metering tablets, wherein tablets can be metered and filled into target containers with increased reliability at high cycle rates according to quantity. This and other objects are achieved by embodiments of this application.

In one exemplary embodiment of the present application, it is provided that metering device includes a fixed device part and a metering element, which rotates in a plane of rotation, having several tablet receiving elements. The plane of rotation lies at an angle of inclination of no more than 30° with respect to the weight force direction. The tablet receiving elements of the rotating metering element are open in at least one lateral direction with reference to the plane of rotation. The fixed device part includes a feeder surface for the tablets which, with reference to the weight force direction, is arranged in the bottom region of the metering element and at the side next to the metering element. The feeder surface borders on the metering element by way of a lead-in edge at the level of the tablet receiving element. The metering element can be realized as a rotating conveyor belt, as a rotating conveyor chain or the like, and is realized in a preferred manner as a metering wheel which is rotatable about a rotational axis. The plane of rotation of the metering element lies in an expedient manner at an angle of inclination of no more than 15° and in particular is almost approximately parallel to the weight force direction.

In another embodiment of the application, the associated method according to the application for metering tablets, a tablet store with tablets is provided in a bottom potion of the metering device with reference to the weight force direction. The metering element is made to rotate, wherein tablets are supplied from the tablet store laterally to the tablet receiving elements by way of the feeder surface. The tablet receiving elements then receive in each case at least one, in a preferred manner precisely one tablet. The geometric development of the tablet receiving elements can be matched in such a manner to the form and size of the tablets to be metered that, for example, two or three tablets pass into one tablet receiving element. In an expedient manner, the geometric development is matched in such a manner that precisely one tablet passes into the tablet receiving elements and consequently one tablet comes to rest in each tablet receiving element. The tablets are then transported in the tablet receiving elements to the tablet outlet by way of the metering element. In a manner described in more detail below, the tablets are counted and are supplied in a counted quantity from the tablet receiving elements through the tablet outlet to a target container.

Different advantages are achieved as a result of the various embodiments of the application. The weight of the tablet store is carried first and foremost or even exclusively by the fixed feeder surface which is associated with the fixed device part. As a result of this and as a result of the only slight—if at all—inclination of the plane of rotation of the metering element, the tablets of the tablet store experience an, at best, only slight pressing pressure against the rotating metering element. The rotation of the metering element induces an only slight inherent movement in the tablet store with very small frictional forces such that the tablets are treated in a manner which protects the material. The risk of fracture and the development of dust are reduced to a minimum. Tablets which stick together as duplicates or triplicates can hardly pass into the tablet receiving elements such that they do not occupy them. Rather, the individual tablet receiving elements remain free to receive tablets as per specification, which increases the effect of separating them into singles or the counting or metering reliability. Unavoidable fragments and dust parts can easily be discharged in the manner described in more detail below without impairing the metering operation. All in all, a high level of operating reliability can be achieved even in the case of high pulse rates or high rotational speeds.

In a preferred variant of the method, the metering element rotates continually, the tablet receiving elements continuously receiving tablets from the tablet store. In the case of a uniform movement with low mass inertia forces, it is possible to achieve high operating speeds with a high volume output. In the case of such continuous operation, different variants of the separating out into singles and metering according to quantity are possible within the framework of the application:

In another advantageous variant, individual contiguous rows which are spaced apart from one another are formed from the continuously received row of tablets. More precisely, as a result of ejecting tablets in a selective manner from their tablet receiving elements, contiguous rows of tablet receiving elements with tablets are formed in a desired, counted number, further rows of empty tablet receiving elements, that is without tablets, being formed between the aforementioned rows. The tablets following one after another in a contiguous row are supplied as a group through the tablet outlet into the target container. Whilst the following empty row of tablet receiving elements without tablets passes the tablet outlet, the target container is changed. The cycle of supplying the tablets to the target container and changing the target container can then start again.

In still another embodiment, the ejected tablets can be guided back into the tablet store so that they are not lost. The number of tablets to be ejected can be freely chosen in order, for example, to meter different quantities dependent on the requirement. This can be carried out, in particular, when, using suitable monitoring elements (sensor, camera, counter), a tablet receiving element that has remained empty in an unwanted manner has been detected. Individual tablets can also be supplied subsequently in conjunction with the selective ejecting process. As a result it can be ensured that the correct number of tablets passes into the target container even in the event of the aforementioned error.

In an advantageous variant of the continuous method, the tablets received to form a continuous uninterrupted row are moved continuously to the tablet outlet. At the tablet outlet, the tablets are ejected from their receiving elements in the desired counted number and are supplied to the target container by way of the tablet outlet. Subsequent tablets are guided past the tablet outlet and back to the tablet store. The target container is changed whilst the tablets are being returned. The cycle of supplying tablets to the target container and changing the target container can then start again. Here too, high volume output rates can be achieved with a high level of processing reliability. In both of the aforementioned cases, without modifying the device the number of tablets to be removed into the respective target container can be varied and adapted to the respective requirements simply by adapting the control system.

A further advantageous variant of the continuous method can be realized using a metering element which comprises at least one continuing and defined row of consecutive tablet receiving elements, which in their number correspond to the desired, counted number of tablets, and which are followed by a segment without tablet receiving elements. At the tablet outlet, the tablets are ejected from the continuing, defined row of tablet receiving elements and are supplied to the target container by way of the tablet outlet. Whilst the subsequent segment without tablet receiving elements passes the tablet outlet, the target container is changed. The cycle of supplying the tablets to the target container and changing the target container can then start again.

In still yet another embodiment, the metering element is a format part where the number of tablets of an individual metering quantity is defined by the number of tablet receiving elements combined in the defined row. An expensive control system can be omitted. Rather, reception, transport and ejection of the tablets is effected in conjunction with each individual tablet receiving element or with the lack of such, as a result of which expenditure on the device and method is kept low whilst the level of process reliability is high.

As an alternative to this, it can be expedient for the metering element to rotate in a pulsed manner. In this connection, no particular measures have to be taken for the period of the target container change. Rather, the metering pulse is measured in such a manner that a row of consecutive tablet receiving elements, which correspond in their number to the desired counted number of tablets, is moved within the named metering pulse to the tablet outlet where the tablets are ejected from their respective tablet receiving elements and are supplied to the target container by way of the tablet outlet. A rest pulse in which the metering element stands still follows the metering pulse. The target container is changed during the rest pulse. Following this, the cycle of the metering pulse and the rest pulse can start again.

Within the framework of the application different possibilities are possible for the physical development of the metering device. For example, in another embodiment, it can be expedient to realize the tablet receiving elements as axially parallel bores in the metering element or in the metering wheel. In a preferred embodiment, the metering element includes a basic body and entrainment elements which project radially from the basic body, wherein the entrainment elements lie spaced apart from one another in the direction of rotation and as a result in each case define between them a tablet receiving element. The metering element consequently obtains a structural shape comparable to a toothed wheel, the teeth of which form the entrainment elements and the tooth spaces of which form the tablet receiving elements. As a result, the tablet receiving elements are not only open at the side for insertion of the tablets but are also open radially outward. The opening in the radial direction enables, on the one hand, optional tablet ejection also in said radial direction. On the other hand, an advantageous possibility to separate off tablet fragments, tablet dust or other unwanted part quantities of the tablet store is created as a result.

In still another variant, with regard to the aforementioned separation, a separation gap, which, with reference to the weight force direction, is arranged in the bottom region and radially outside of the metering element, is advantageously realized in the fixed device part, wherein the separation gap is defined at the side by the lead-in edge of the feeder surface. In an expedient further development, the separation gap is connected to a suction device. In particular, the entrainment elements, radially outside, in each case comprise a tapered portion, by way of which they project into the separation gap when running through the bottom position or when running through the gap region.

In a further example, the lead-in edge of the feeder surface ensures that a tablet passes into the tablet receiving element between two entrainment elements and at the same time prevents the tablet from being able to drop down out of the tablet receiving element through the separation gap. This naturally presupposes a geometric adaptation of the tablet gap to the tablets to be metered in such a manner that the width of the separation gap is smaller than the smallest cross sectional measurement of the tablets. At the same time, however, the separation gap is wide enough to enable tablet fragments, tablet dust or other unwanted part quantities of the tablet store to be removed through the separation gap out of the tablet receiving element. This latter can occur as a result of the acting weight force. The suction device is used advantageously in a supporting manner, as a result of which the tablet receiving element and also the separation gap itself are kept free in a reliable manner. This latter is also promoted as a result of the portion of the respective entrainment element which tapers into the separation gap. The named portion, in this case, also helps to keep tablets correctly as per specification in the respective tablet receiving element and at the same time to avoid jamming, tilting or the like.

In another variant, the named entrainment elements comprise in each case a front entrainment face, with reference to the direction of rotation, against which one tablet comes to abut in each case. The front entrainment faces can be aligned in a radial manner. In an advantageous manner, in each case they are at a positive entrainment angle with reference to the radial direction, as a result of which they advance or transport the respective tablets not only in the direction of rotation but also, at the same time, lift them up from the feed surface or the lead-in edges. This contributes to avoiding any jamming or the like.

In still another example, the feed surface is given central importance for supplying the tablets laterally from the tablet store into the respective tablet receiving elements. It can be aligned in a horizontal manner, the lateral feed being provided, for example, by way of a vibratory movement or other measures such as suction or blast air or the like. In particular, however, the feed surface is inclined toward the metering element at a plane angle of no more than 50° and in particular of no more than 30° with respect to the horizontal direction. As a result of the angle of inclination, the tablets or the tablet store slip automatically to the side without any additional effort onto the metering element and also into the laterally open metering receiving element. The aforementioned defining of the plane angle ensures that the tablets are only pressed lightly, brought about by the weight force of the tablets, against the rotating metering element whilst the weight force is supported overall at least for the most part by the fixed feeder face. The tablets consequently experience only a slight load with a low level of abrasion and a low risk of fracture.

Pursuant to another advantageous embodiment, the metering device comprises a tablet outlet with a counting device for the tablets. As a result, reliable counting of the tablets can be ensured even in the case of high operating speeds. There is no need to monitor that the tablet receiving element is properly filled by using image processing which is difficult to realize at high speeds. As the counting takes places directly at the tablet outlet, that is to say at the actual end of the metering operation, it is ensured that the counted number of tablets also actually pass into the target container. Insofar as, in this connection, a lesser number is ascertained, the missing number of tablets can be supplied additionally by way of the variably actuatable metering device according to the application. All in all, it ensures that each target container contains precisely the desired number of individual tablets. 100% waste reduction is possible.

In an expedient embodiment, in the direction of rotation the metering element comprises a row of tablet receiving elements which, with reference to the plane of rotation, are open in only one side direction and are closed in the opposite side direction. A fixed wall part or a wall part which rotates with the metering element can be used as a side closure. On one hand, there is low expenditure on the device. On the other hand, simple possibilities for tablet ejection are produced, in particular in the lateral direction. As an alternative to this, it can be expedient for the metering element to comprise on the two opposite sides tablet receiving elements which are open toward the lateral faces of the metering element and which are separated from one another by way of a central partition wall. Where the tablets are fed from a tablet store on both sides, the ejection rate can be increased.

In a preferred embodiment, several metering elements which are realized as metering wheels are combined to form one unit which is rotatable about a common rotational axis, wherein the metering wheels are provide with spokes and run through a common tablet store. The metering wheels, in this case, are fed in an advantageous manner from a common tablet store. Where the fill level is correspondingly sufficient, the tablets can be moved through between the spokes and consequently lead to a fill level balancing process. Consequently, a sufficient tablet store abuts against all the metering wheels. Using the named realization, as required, one row or lane of target containers each can be filled simultaneously by way of each metering wheel whilst, as an alternative to this or in combination therewith, it is possible to fill one row or lane of target containers with correspondingly increased tablet ejection by way of several metering wheels.

In an expedient manner, the fixed device part comprises a fill level sensor which is directed through between the spokes onto the tablet store, and wherein, in particular, the spokes are spaced apart from one another at irregular angular distances. As a result, individual or all the metering wheels running unintentionally empty is avoided with only one single fill level sensor. The irregular angular distances between the spokes ensure that, in particular in the case of pulsed operation, the spokes do not always come to rest in the same position and consequently cannot cover the fill level sensor.

In another embodiment of the present application, A metering device for metering tablets is provided and has a fixed device part and a metering element. The metering element rotates in a plane of rotation and has several tablet receiving elements. The plane of rotation lies at an angle of inclination of no more than 30° with respect to the weight force direction, and the tablet receiving elements are open in at least one lateral direction with reference to the plane of rotation and the fixed device part. The embodiment includes a feeder surface for the tablets which, with reference to the weight force direction, is arranged in the bottom region of the metering element and at the side next to the metering element. The feeder surface borders on the metering element by way of a lead-in edge at the level of the tablet receiving elements.

In still another embodiment, the metering element is realized as a metering wheel which is rotatable about a rotational axis. Optionally, the plane of rotation lies at an angle of inclination of no more than 15° with respect to the weight force direction, or the plane of rotation lies parallel to the weight force direction.

In yet another optional embodiment, the metering element includes a basic body and entrainment elements which project from the basic body in a radial manner. The entrainment elements lie spaced apart from one another in a direction of rotation and as a result in each case define between them a tablet receiving element.

Still a further variant includes a separation gap, which, with reference to the weight force direction, is arranged in the bottom region as well as radially outside the metering element, and which is realized in the fixed device part. The separation gap is defined radially inside by the lead-in edge of the feeder surface. Optionally, the separation gap is connected to a suction device.

Another embodiment provides that the entrainment elements, radially outside, in each case comprise a tapered portion by way of which they project into the separation gap. The entrainment elements may also comprise a front entrainment face, with reference to the direction of rotation, wherein the entrainment faces lie in each case at a positive entrainment angle with reference to the radial direction.

Still another example of the application includes a feeder surface inclined toward metering element at a surface angle of no more than 50° with respect to the horizontal direction. Optionally, the feeder surface is inclined toward metering element at a surface angle of no more than 30° with respect to the horizontal direction.

In another variant, the metering device comprises a tablet outlet with a counting device for the tablets. Another variant provides that in the direction of rotation the metering element comprises a row of tablet receiving elements which, with reference to the plane of rotation, are open in only one lateral direction and closed in the opposite lateral direction.

In still yet another embodiment, on the two opposite sides the metering element comprises tablet receiving elements which are open toward the lateral faces of the metering element and which are separated from one another by way of a central partition wall.

Several metering elements may also be realized as metering wheels and may be combined to form one unit which is rotatable about a common rotational axis in another embodiment. The metering wheels are provided with spokes and run through a common tablet store. A fill level sensor may also be provided which is directed through between the spokes onto the tablet store. Additionally, the spokes may be spaced apart from one another at irregular angular distances.

An embodiment of the method for metering tablets using a metering device according to the present application includes forming contiguous rows of tablet receiving elements containing tablets in a desired, counted number as a result of ejecting tablets from their tablet receiving elements in a selective manner, wherein between the rows of tablet receiving elements with tablets further rows of tablet receiving elements without tablets are formed. A cycle is repeated including supplying through the tablet outlet to the target container the tablets in one of the contiguous rows to tablet receiving elements containing tablets, and changing the target container while a subsequent row of tablet receiving elements without tablets passes the tablet outlet.

Another embodiment of the method includes continuously guiding to the tablet outlet the tablet receiving elements which are continuously provided with tablets. The method provides for repeating a cycle involving ejecting the tablets from their tablet receiving elements in the desired, counted number at the tablet outlet and supplying the tablets to the target container by way of the tablet outlet, guiding any following tablets past the tablet outlet and back to the tablet store, and changing the target container while the tablets are being returned.

In another variant of the method, the metering element comprises at least one continuing and defined row of consecutive tablet receiving elements, which correspond in their number to the desired, counted number of tablets, and which is followed by a segment without tablet receiving elements. The variant also involves ejecting the tablets at the tablet outlet from the continuous, defined row of tablet receiving elements and supplying the tablets to the target container by way of the tablet outlet and changing the target container while the following segment without any tablet receiving elements passes the tablet outlet.

Still another optional example involves repeating a cycle involving rotating the metering element in a pulsed manner, moving a row of consecutive tablet receiving elements, which correspond in their number to the desired, counted number of tablets, within a metering pulse to the tablet outlet where the tablets are ejected from their respective tablet receiving elements and supplying the tablets to the target container by way of the tablet outlet, following the metering pulse with a rest pulse in which the metering element stands still, and changing the target container during the rest pulse.

Another exemplary embodiment includes tablets which are supplied to the target container and counted in the tablet outlet by way of the counting device, and in the case of a lesser quantity being ascertained, the number of tablets missing is additionally supplied.

Where unwanted part quantities of the tablet store such as tablet fragments or tablet dust are present, in one embodiment such quantities are removed through the separation gap. This can optionally be accomplished by sucking out through the separation gap by way of the suction device.

Further objects, features, and advantages of the present application will become apparent from the detailed description of preferred embodiments which is set forth below, when considered together with the figures of drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the application are described in more detail below by way of the figures of drawing, in which:

FIG. 1 shows a schematic front view of a first exemplary embodiment of a metering device according to the application with a rotatable metering wheel, at the circumference of which are situated entrainment elements for tablets, in conjunction with a tablet store;

FIG. 2 shows a sectional view of a detail of the metering wheel according to FIG. 1 with one single tablet receiving element in conjunction with a feeder surface when receiving one single tablet;

FIG. 3 shows a variant of the arrangement according to FIG. 2 with two tablet receiving elements located laterally opposite one another and associated feeder surfaces;

FIG. 4 shows an enlarged view of a detail of the arrangement according to FIG. 1 in the region of the tablet receiving elements and associated entrainment elements;

FIG. 5 shows a representation of a cutout of the arrangement according to FIG. 1 with details of a separation gap arranged in the bottom region;

FIG. 6 shows a variant of the arrangement according to FIG. 5 with a segmented separation gap;

FIG. 7 shows an enlarged representation of a detail of a portion of an alternative embodiment of the metering wheel according to FIGS. 1 to 6 with tablet receiving elements combined in groups;

FIG. 8 shows a longitudinal sectioned representation of an embodiment of the metering device with several metering wheels arranged along a common axis of rotation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a schematic front view of a first exemplary embodiment of a metering device 1 for tablets 2 according to the application. The tablets 2 in the preferred exemplary embodiment shown are micro tablets with a diameter of 3.0 mm or less which are to be metered in each case in a fixed number and filled into target containers (not shown) such as two-piece capsules or the like. Larger tablets can also be metered in place of micro tablets. In each case, the metering is effected according to quantity by tablets 2 being separated out into singles from a vibrated tablet store 19, measured in the predefined quantity and then supplied to the target container (not shown).

The metering device 1 includes a fixed device part 3 and a metering element which rotates in a plane of rotation E. The metering element, in the preferred exemplary embodiment shown, is realized as a metering wheel 5 which is rotatable about a rotational axis 4. In the representation according to FIG. 1, the plane of rotation E lies in the drawing plane, whilst the rotational axis 4 is perpendicular thereto. In the following description, for the purposes of simplicity, reference is made to the metering wheel 5. However, the same also applies to other suitable metering elements within the framework of the application, for example in the form of a rotating conveyor belt or a rotating conveyor chain.

The metering wheel 5 comprises several tablet receiving elements 6 which, in the exemplary embodiment according to FIG. 1, are arranged uniformly and equidistantly along the wheel circumference. The tablet receiving elements 6 can be bores, blind holes, indentations or the like in at least one lateral face of the metering wheel 5. In the exemplary embodiment shown, the tablet receiving elements 6 are realized as gaps between entrainment elements 10 which protrude radially outward from a basic body 9 of the metering wheel 5. As a result, the tablet receiving elements 6 are open radially outward. In each case, however, they are open in at least one lateral direction, that is in a direction parallel to the rotational axis 4 or perpendicular to the plane of rotation E, as can also be seen from the representation according to FIGS. 2 and 3. Each tablet receiving element 6 is defined by one entrainment element 10 each, at least to the rear in opposition to the direction of rotation 11, in the exemplary embodiment shown also to the front in the direction of rotation 11.

The metering device 1 is shown in its usual operating position relative to the downwardly acting weight force direction which is specified by an arrow 27. The fixed device part 3, that is not rotating with the metering wheel 5, includes a feeder surface 7 for the tablets 2, which is described in more detail in FIGS. 2 and 3 and is arranged, with reference to the weight force direction, in the bottom region of the metering device 1 and of the metering wheel 5. From an overall view of FIGS. 2 and 3 it can also be seen that the feeder surface 7 is additionally also arranged laterally next to the metering wheel 5. In the front view according to FIG. 1, the feeder surface 7 is curved in the form of a circular ring segment following the development of the tablet receiving elements 6 and is arranged in such a manner in the region of or at the level of the tablet receiving elements 6 that the tablet receiving elements 6 are open directly above the feeder surface 7 in the lateral or axial direction.

A large quantity of tablets 2 are supplied as bulk material by way of a tablet feeder 24, said tablets forming a tablet store 19 which rests on the feeder surface 7. The metering wheel 5 is provided in the region of its basic body 9 with spokes 18, between which windows 22 are realized. The spokes 18 are at irregular angular spacings to one another. The fixed device part 3 includes a fill level sensor 20 which is directed between the spokes 18 through the windows 22 onto the tablet store 19, checks the fill level and consequently ensures a sufficient fill level of tablets 2 in the tablet store 19.

Also in the bottom region of the metering device 1, but in the direction of rotation 11 of the feeder surface 7 and downstream of the tablet store 19, the metering device 1 is provided with a tablet outlet 16 as well as, as an option, with an outlet 25 which is once again downstream and in this case borders directly on the feeder surface 7. At least in the upper region of the metering device 1, proceeding from the feeder surface 7 up to at least the tablet outlet 16, a cover 26 is provided as part of the fixed device part 3, said cover covering the circumferential region of the metering wheel 5 including its tablet receiving elements 6 and its entrainment element 10.

FIG. 2 shows a sectioned view of a detail of the metering wheel 5 according to FIG. 1 in the region of one single tablet receiving element 6. In the region of the tablet receiving element 6 the thickness of the metering wheel 5, at least however the clearance of the metering receiving element 6 is matched in such a manner to the size of the tablets 2 that at least one single tablet 2, in this case precisely one single tablet fits completely in the tablet receiving element 6, a second tablet 2, however, is not able to pass into the tablet receiving element 6 at the same time. From an overall view together with FIG. 4 it can also be seen that the feeder surface 7 borders on the metering wheel 5 by way of a lead-in edge 8 at the level of the tablet receiving element 6 in such a manner that the tablet 2, proceeding from the feeder surface 7, is able to pass into the tablet receiving element 6. In other words, with reference to the radial direction which is specified by an arrow 31 and proceeds from the rotational axis 4, the lead-in edge 8 is arranged relative to the radially inner bottom of the tablet receiving element 6 such that a sufficiently large lateral window of the tablet receiving element 6 remains for receiving the tablet 2.

In an advantageous manner, the tablets 2 are automatically fed laterally into the tablet receiving elements 6 as a result of the weight force acting on the tablets 2. To this end, the feeder surface 7—measured in a plane perpendicular to the plane of rotation E—is inclined toward the metering wheel 5 at a plane angle γ. The plane angle γ is measured in the section shown according to FIG. 2 between the feeder surface 7 and the horizontal direction, and in this embodiment is no more than 50°, in particular no more than the 30° provided in this case. As a result, on the one hand a sufficient downwardly acting force is ensured. On the other hand, the downwardly acting force is not excessively large with the result that the tablet store 19 which rests on the feeder surface 7 is not pressed excessively against the metering wheel 5 and as a consequence is not made to move excessively.

The feeder surface 7 can be made to vibrate (horizontally, vertically or in a combination thereof) in a manner which supports the named downwardly acting force. A suction air draft or a blast air draft as well as a combination of the two can also be used in a supporting manner. In addition, it can be expedient to develop the surface of the feeder surface 7 in a structured manner. The surface structuring can be realized such that tablets 2 that would like to settle into one tablet receiving element at the same time and in this case mutually obstruct one another, are influenced such that in a preferred manner one of said tablets 2 is slipped in. This can be achieved in particular as a result of a wave profile transversely to the inlet direction, peaks and troughs extending transversely to the plane of rotation E and comprising a wave length which corresponds to the distance between the tablet receiving elements 6 and the entrainment elements 10. As a result, the tablets 2 are aligned spaced apart from one another by a distance which corresponds to the distance between the tablet receiving elements 6, as a result of which orderly merging is promoted.

Corresponding to the representation according to FIG. 2, the plane of rotation E lies almost approximately, in this case precisely parallel to the weight force direction which is specified by an arrow 27. The rotational axis 4 (FIGS. 1 and 4) is consequently horizontal thereto. Consequently, the plane of rotation E and the weight force direction 27 enclose an angle of inclination α=0°. However, a slight inclination of the rotational axis 4 and consequently of the plane of rotation E can also be expedient, in this case the angle of inclination a expediently being no more than 30° and in particular no more than 15°.

In the exemplary embodiment according to FIGS. 1 and 2, the metering wheel 5 comprises only or precisely one row of tablet receiving elements 6 in the direction of rotation. Corresponding to the cross sectional representation according to FIG. 2, said tablet receiving elements, with reference to the plane of rotation E, are open in only one lateral direction which is specified by an arrow 28. They are closed in the opposite lateral direction, for which purpose in this case a wall part 30 is provided as a cover. The wall part 30 can be part of the fixed device part 3. In the exemplary embodiment shown, it is part of the metering wheel 5 and is entrained by the same. As an alternative to this, a realization as is shown in FIG. 3 can be expedient. In this connection, on the two opposite sides the metering wheel 5 comprises one rotating row of tablet receiving elements 6, 6′ each, which are separated from one another by way of a central partition wall 17. In this connection, the tablet receiving elements 6, 6′ are open in each case toward the associated lateral face of the metering wheel 5 in the associated lateral directions specified by arrows 28, 29. Analogously to the representation according to FIG. 2, in this case feeder surfaces 7, 7′ with lead-in edges 8, 8′ border on the two sides.

It can also be seen from the representation according to FIG. 2 that a separation gap 12, which is arranged in the bottom region and radially outside the metering wheel 5 with reference to the weight force direction 27, is realized in the fixed device part 3. The separation gap 12 is defined radially inside, in this case therefore upward, by way of the lead-in edge 8 of the feeder surface 7. The separation gap 12 is defined by the wall part 30 in the opposite lateral direction such that the tablets 2 abut against the lead-in edge 8 on the one side and against the wall part 30 on the opposite side. The width of the separation gap 12 shown in cross section here is smaller than the smallest cross sectional dimension of the tablet 2 such that the tablet 2 gets caught on the lead-in edge 8 and is not able to drop down through the separation gap 12 out of the tablet receiving element 6.

In a representation of a cutout, FIGS. 5 and 6 each show variants of the arrangement according to FIGS. 1 and 2 in a sectioned front view with details for the development of the separation gap 12 shown in FIGS. 2 and 3. Corresponding to the representation according to FIG. 5, the separation gap 12 extends in the direction of rotation of the metering wheel 5 over an angular region which covers several tablet receiving elements 6. The separation gap 12 is connected to a schematically indicated suction device 13 so as to transmit pressure and flow. A suction air flow is created which, on the one hand, sucks tablets 2 into the respective tablet receiving elements 6 corresponding to the representation according to FIG. 2. On the other hand, it is clear from looking at FIGS. 2 and 5 that tablets 2 that are undersized, tablet fragments, tablet dust or the like are not able to get caught on the lead-in edge 8 and are consequently sucked out of the tablet receiving elements 6 through the separation gap 12. In the alternative embodiment according to FIG. 6, the separation gap 12 is divided into different segments, only each next but one segment being connected to the suction device 13. During the rotating movement of the metering wheel 5, each tablet receiving element 6 is consequently acted upon in an intermittent or pulsating manner with negative pressure, which can promote the slipping-in of the tablets 2 and the sucking-up of unwanted material.

With reference to FIGS. 2 and 3 again, it can also be seen that in the preferred exemplary embodiments shown the entrainment elements 10 comprise, radially outside, in each case a portion 14 which tapers in the direction of the width or axis and by way of which they project into the separation gap 12. On the one hand, as a result, clogging of the separation gap 12 is prevented. On the other hand, the entrainment elements 10 are in full surface contact with the tablets 2 even where the tablets 2, corresponding to the representation according to FIG. 2, come to rest in part in the separation gap 12.

FIG. 4 shows an enlarged view of a detail of the arrangement according to FIG. 2 corresponding to the intersection line IV-IV indicated there. The radial direction which proceeds from the rotational axis 4 is specified by an arrow 31. It can be seen that the entrainment elements 10 comprise, with reference to the direction of rotation, a front entrainment face 15 against which the respective tablets 2 abut as a result of the rotational movement of the metering wheel 5. In the preferred exemplary embodiment shown, the entrainment face 15 lies at a positive entrainment angle β with reference to the radial direction 31. Corresponding to the representation according to FIG. 4, the entrainment angle β is positive in such a case in which the entrainment face 15 is inclined in the direction of rotation 11 proceeding from radially inside to radially outside. As a result, the feeder surface exerts on the tablet 2 not only a feed force in the direction of rotation 11, but also in opposition to the radial direction 31 a lifting force which reduces the pressing pressure of the tablet 2 onto the lead-in edge 8 or which even raises the tablet 2 from the lead-in edge 8 in opposition to the radial direction 31.

FIG. 8 shows a longitudinal sectional representation of an embodiment of the metering device 1 with several metering wheels 5 which are arranged on a common axis component 25 along the axis of rotation 4. Each individual metering wheel 5 has associated therewith at least one feeder surface 7 each. The individual metering wheels 5 and feeder surfaces 7 correspond in their design to the previously described designs. Viewing this together with FIG. 1 it is clear that a tablet store 19 which rests on the feeder surfaces 7 is able to be distributed through the windows 22 between the spokes 18 in a uniform manner such that all the metering wheels 5 are loaded from the same tablet store 19 at a sufficiently uniform fill level. The fill level of the common tablet store 19 can be monitored through the windows 22 between the spokes 18 by just one single fill level sensor 20.

With reference to the afore-described Figures, an embodiment of the method according to the application for the metering of tablets in terms of quantities by way of the metering device 1 according to the application is realized as follows:

A fairly large volume of tablets 2 is initially poured in as bulk material through the tablet feed 24, as a result of which a tablet store 19 is realized resting on the feeder surface 7 in the bottom portion of the metering device 1. The metering wheel 5 is then set into motion rotating about the rotational axis 4 in the direction of rotation 11. In this connection, tablets 2 are supplied laterally from the tablet store 19 to the tablet receiving elements 6 in the above-described manner by way of the feeder surface 7. In this case, the tablet receiving elements 6, in dependence on the geometric adaptation to the form and size of the tablets 2, in each case receive one or several, in this case in a preferred manner precisely one tablet 2. The tablets 2 received in this manner, lying in the tablet receiving elements 6, are transported to the tablet outlet 16 by way of the metering wheel 5 and there, in a counted number are supplied from the tablet receiving elements 6 through the tablet outlet 16 to the target container (not shown) which has already been mentioned previously. In the region of the feeder surface 7, the tablet receiving elements 6 are open at the side such that they are able to receive the tablets 2. In the remaining circumferential region, the metering wheel 5 is covered by way of the cover 26 in such a manner that the received tablets 2 are not able to fall unintentionally out of their tablet receiving elements 6.

In a first preferred embodiment of the method according to the application, the metering element rotates continuously. In other words, the metering wheel 5 rotates about its rotational axis 4 at least approximately uniform angular speed. Corresponding to the embodiment according to FIG. 1, in which the tablet receiving elements 6 are distributed uniformly over the circumference of the metering wheel 5, the tablet receiving elements 6 continuously receive tablets 2 from the tablet store 19. In order to ensure that from this a certain metering quantity, that is a certain number of tablets 2 passes into the target container, the tablets have to be counted and have to pass in the counted quantity from the tablet receiving elements 6 through the tablet outlet 16 into the target container.

In a first variant of the continuous method, the tablets 2 are selectively ejected for this purpose from their tablet receiving elements 6. This can be effected, for example, in the upper portion of the metering device 1 which is shown as having been removed in FIG. 1. The ejected tablets 2 fall back into the tablet store 19. As indicated schematically in the left top third of the representation according to FIG. 1, contiguous rows 31 of tablet receiving elements 6 with tablets 2 entrained therein as well as rows 32 of empty tablet receiving elements 6 without tablets 2 are formed alternately as a result of said selective ejection. Tablet receiving elements with tablets 2 are symbolized here in a schematic manner by way of circles whilst empty places, that is tablet receiving elements without tablets are symbolized by way of crosses. Each individual contiguous row 31 includes overall the desired, counted number of tablets 2 which is supplied to the target container through the tablet outlet 16. The row 32 following this in the direction of rotation 11 is matched in its number of empty tablet receiving elements 6 in such a manner to the rotational speed of the metering wheel 5 that when the movement of the metering wheel 5 is uninterrupted, a time window is created in which no tablets 2 are separated off through the tablet outlet 16. In said time window, that is whilst the row 32 of empty tablet receiving elements 6 passes the tablet outlet 16, the target container is changed. The new target container is then filled from the following row 31, the tablet receiving elements 6 of which is loaded with tablets 2. A cycle in which, with the metering wheel 5 rotating continuously, target containers are alternately filled with a desired, counted number of tablets 2 and then are exchanged, is produced from the above pattern.

A camera 23, by way of which the regular loading of the tablet receiving elements 6 with or without tablets 2 can be checked by way of image-processing monitoring, can be arranged as an option, on the entry side of the tablet outlet 16, in this case in the upper portion of the metering device 1. If a tablet 2 is missing from the provided tablet receiving element 6, counter measures can be taken, for example by subsequently delivering one single tablet 2 or by interrupting the ejection operation from the tablet outlet 16. In particular, however, it is expedient, corresponding to the representation according to FIG. 1, to provide the tablet outlet 16 with a counting device 21 for tablets 2. In a preferred manner, a small bore (not shown) branches off from the tablet receiving elements 6 for this purpose, the counting device 21 being arranged outside said bore. The sensor of the counting device 21 looks through the named bore into the tablet outlet 16 and counts the tablets 2 moving through. A small cavity in which a certain over pressure prevails is realized between the sensor of the counting device 21 and the bore. As a result, the counting device 21 or the sensor thereof avoids getting dusty in spite of a high level of dust developing during the metering operation. The bore too is always kept free such that reliable counting is possible. Unlike in the case of optical image processing, precise counting can be carried out even at high throughput speeds and high throughput volumes in this case with low technical expenditure. In particular, however, it is ensured that only those tablets 2 which are actually separated off through the tablet outlet 16 and which pass into the target container are counted. Faults caused by tablets 2 not being separated off and jamming in the tablet receiving elements 6 as well as by tablets which have fallen out beforehand are excluded by said form of counting operation.

In a second variant of the continuous method according to the application, the tablet receiving elements 6 which are continuously loaded with tablets 2 are guided continuously to the tablet outlet 16. Deviating from the afore-described method, the tablets are not ejected selectively en route. Rather, the tablets 2 are not ejected from their tablet receiving elements 6 in the desired, counted number until at the tablet outlet 16 and they are supplied to the target container by way of the tablet outlet 16. The ejection operation is interrupted once the predefined or desired number is reached. Subsequent tablets which are entrained in the respective tablet receiving elements 6 are guided past the tablet outlet 16 and back to the tablet store 19. The target container is changed during said returning of the tablets 2. Following this, the cycle of supplying tablets to the target container and changing the target container starts again.

A third variant of the continuous method according to the application makes use of an embodiment of the metering wheel 5 which is shown in portions in a frontal view in FIG. 7. The metering wheel 5 comprises at least one, in this case several continuous rows 33 which are defined in the direction of rotation 11 of consecutive tablet receiving elements 6. The tablet receiving elements 6 of one single row 33 correspond in their number to the desired number of tablets 2 to be counted. Each defined row 33 is followed by a segment 34 in which no tablet receiving elements 6 are realized. The tablet receiving elements 6 receive the tablets 2 in the above-described manner. With reference at the same time to the remaining Figures, the tablets 2 are now ejected from one single defined row 33 at the tablet outlet 16 and are supplied to the target container by way of the tablet outlet 16. With the metering wheel 5 continuing to rotate continuously, the segment 34 without tablet receiving elements 6 then passes the tablet outlet 16 such that no tablets 2 are separated off during this period. The length of the segment 34 measured in the direction of rotation 11 is matched to the rotational speed of the metering wheel 5 in such a manner that a sufficient time window remains to change the target container. The changeover is therefore undertaken whilst the segment 34 without tablet receiving elements 6 passes the tablet outlet 16. With the metering wheel 5 rotating continuously, this is then followed by the next defined row 33 with filled tablet receiving elements 6 such that the cycle of supplying tablets to the target container and changing the target container can start again.

Within the framework of the application a pulsed method can be provided as an alternative method. In this connection, the metering wheel 5 rotates in pulsed manner. The metering wheel 5 realizes a rotational movement during a metering pulse. The metering pulse is measured in such a manner that consecutive tablet receiving elements 6, which correspond in their number to the desired, counted number of tablets 2, pass the tablet outlet 16 within said metering pulse. There the tablets are ejected from their respective tablet receiving elements 6 in the named number and are supplied to the target container by way of the tablet outlet 16. The metering pulse is followed by a rest pulse in which the metering wheel 5 stands still. The target container is changed during the rest pulse. As soon as this happens, the cycle of metering pulse and rest pulse starts again.

In all the variants of the method according to the application, the fill level in the tablet store 19 can be monitored in particular using the fill level sensor 20 according to FIG. 1, image-processing monitoring by way of the camera 23 and in particular counting of the tablets 2 actually ejected from the tablet outlet 16 can be monitored by way of the counting device 21. If, in this connection, it is ascertained that not enough tablets 2 have been ejected, the corresponding missing quantity can be supplied additionally in a following operation.

It has been pointed out further above that as a result of the development according to the application, tablets 2 which stick to one another in the form of duplicates or triplicates are stopped from passing into the tablet receiving elements 6. As therefore only tablets 2 as per specification are removed from the tablet store 19, the concentration of tablets 2 which are not as per specification is increased over the course of a fairly long metering operation in the tablet store 19. Consequently, it can become necessary from time to time to empty the tablet store 19 from the metering device 1. The outlet 25 shown in FIG. 1 is provided for this purpose. As a result of rotating the metering wheel 5 in the opposite direction to the usual direction of rotation 11, the tablet store 19 is removed through the outlet 25 and can be replaced by fresh tablets 2 through the tablet feed 24.

Insofar as not described expressly to the contrary, the different physical embodiments and method variants concur with one another in their remaining features, references and options. All the described embodiments are advantageous examples of the application, but do not exclude deviating embodiments within the framework according to the application.

The foregoing description of preferred embodiments has been presented for purposes of illustration and description only. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and modifications and variations are possible and/or would be apparent in light of the above teachings or may be acquired from practice of the application. The embodiments were chosen and described in order to explain the principles of the application and its practical application to enable one skilled in the art to utilize the application in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims appended hereto and that the claims encompass all embodiments of the application, including the disclosed embodiments and their equivalents.

Claims

1. A metering device for metering tablets, said metering device comprising:

a fixed device part,

a metering element, which rotates in a plane of rotation, having several tablet receiving elements, wherein a plane of rotation lies at an angle of inclination of no more than 30° with respect to the weight force direction, wherein the tablet receiving elements are open in at least one lateral direction with reference to the plane of rotation and the fixed device part,

a feeder surface for the tablets which, with reference to the weight force direction, is arranged in the bottom region of the metering element and at the side next to the metering element, wherein the feeder surface borders on the metering element by way of a lead-in edge at the level of the tablet receiving elements.

2. The metering device according to claim 1, wherein the metering element is realized as a metering wheel which is rotatable about a rotational axis.

3. The metering device according to claim 1, wherein the plane of rotation lies at an angle of inclination of no more than 15° with respect to the weight force direction.

4. The metering device according to claim 1, wherein the plane of rotation lies parallel to the weight force direction.

5. The metering device according to claim 1, wherein the metering element includes a basic body and entrainment elements which project from the basic body in a radial manner, wherein the entrainment elements lie spaced apart from one another in a direction of rotation and as a result in each case define between them a tablet receiving element.

6. The metering device according to claim 5, wherein a separation gap, which, with reference to the weight force direction, is arranged in the bottom region as well as radially outside the metering element, is realized in the fixed device part, wherein the separation gap is defined radially inside by the lead-in edge of the feeder surface.

7. The metering device according to claim 6, wherein the separation gap is connected to a suction device.

8. The metering device according to claim 5, wherein the entrainment elements, radially outside, in each case comprise a tapered portion by way of which they project into the separation gap.

9. The metering device according to claim 5, wherein the entrainment elements comprise a front entrainment face, with reference to the direction of rotation, wherein the entrainment faces lie in each case at a positive entrainment angle with reference to the radial direction.

10. The metering device according to claim 1, wherein the feeder surface is inclined toward metering element at a surface angle of no more than 50° with respect to the horizontal direction.

11. The metering device according to claim 1, wherein the feeder surface is inclined toward metering element at a surface angle of no more than 30° with respect to the horizontal direction.

12. The metering device according to claim 1, wherein metering device comprises a tablet outlet with a counting device for the tablets.

13. The metering device according to claim 1, where in the direction of rotation the metering element comprises a row of tablet receiving elements which, with reference to the plane of rotation, are open in only one lateral direction and closed in the opposite lateral direction.

14. The metering device according to claim 1, wherein on the two opposite sides the metering element comprises tablet receiving elements which are open toward the lateral faces of the metering element and which are separated from one another by way of a central partition wall.

15. The metering device according to claim 1, wherein several metering elements which are realized as metering wheels are combined to form one unit which is rotatable about a common rotational axis, wherein the metering wheels are provided with spokes and run through a common tablet store.

16. The metering device according to claim 15, wherein the fixed device part comprises a fill level sensor which is directed through between the spokes onto the tablet store.

17. The metering device according to claim 16, wherein the spokes are spaced apart from one another at irregular angular distances.

18. A method for metering tablets using a metering device according to claim 1, wherein the method comprises:

providing a tablet store with tablets in a bottom portion of the metering device with reference to the weight force direction;

rotating the metering element and supplying tablets from the tablet store laterally to the tablet receiving elements by way of the feeder surface;

receiving at least one tablet in each tablet receiving element;

transporting the tablets in the tablet receiving elements to the tablet outlet by way of the metering element;

counting the tablets and supplying said tablets in a counted number from the tablet receiving elements through the tablet outlet to a target container.

19. The method according to claim 18, wherein the tablet receiving elements receive precisely one tablet in each case.

20. The method according to claim 18, wherein the metering element rotates continually, wherein the tablet receiving elements continuously receive tablets.

21. The method according to claim 20, further comprising:

forming contiguous rows of tablet receiving elements containing tablets in a desired, counted number as a result of ejecting tablets from their tablet receiving elements in a selective manner, wherein between the rows of tablet receiving elements with tablets further rows of tablet receiving elements without tablets are formed; and

repeating a cycle comprising the following steps:

(a) supplying through the tablet outlet to the target container the tablets in one of the contiguous rows to tablet receiving elements containing tablets, and

(b) changing the target container while a subsequent row of tablet receiving elements without tablets passes the tablet outlet.

22. The method according to claim 20, further comprising:

continuously guiding to the tablet outlet the tablet receiving elements which are continuously provided with tablets; and

repeating a cycle comprising the following steps:

(a) ejecting the tablets from their tablet receiving elements in the desired, counted number at the tablet outlet and supplying the tablets to the target container by way of the tablet outlet,

(b) guiding any following tablets past the tablet outlet and back to the tablet store, and

(c) changing the target container while the tablets are being returned.

23. The method according to claim 20, wherein the metering element comprises at least one continuing and defined row of consecutive tablet receiving elements, which correspond in their number to the desired, counted number of tablets, and which is followed by a segment without tablet receiving elements, wherein the method further comprises:

repeating a cycle comprising the following steps:

(a) ejecting the tablets at the tablet outlet from the continuous, defined row of tablet receiving elements and supplying the tablets to the target container by way of the tablet outlet, and

(b) changing the target container while the following segment without any tablet receiving elements passes the tablet outlet.

24. The method according to claim 18, further comprising:

repeating a cycle comprising the following steps:

(a) rotating the metering element in a pulsed manner,

(b) moving a row of consecutive tablet receiving elements, which correspond in their number to the desired, counted number of tablets, within a metering pulse to the tablet outlet where the tablets are ejected from their respective tablet receiving elements and supplying the tablets to the target container by way of the tablet outlet,

(c) following the metering pulse with a rest pulse in which the metering element stands still, and

(d) changing the target container during the rest pulse.

25. The method according to claim 18, wherein the tablets which are supplied to the target container are counted in the tablet outlet by way of the counting device, and in the case of a lesser quantity being ascertained, the number of tablets missing is additionally supplied.

26. The method according to claim 18, wherein unwanted part quantities of the tablet store such as tablet fragments or tablet dust are removed through the separation gap.

27. The method according to claim 26, wherein the unwanted part quantities are sucked out through the separation gap by way of the suction device.