Dosing device, assembly for such a dosing device and method for actuating a closure of a dosing device

Abstract

Dosing device for dosing bulk material, with a selectively operable closure, the dosing device comprising - a discharge member rotatably arranged within a conveying channel for conveying the bulk material within the conveying channel along a conveying direction towards an outlet opening of the conveying channel, wherein the discharge member has a shaft which is mounted beyond the outlet opening in the conveying direction, or is connected to such a shaft, and - a closure element movable between an operating position and a closure position along a movement path for at least partially closing the outlet opening, wherein the shaft extends through the closure element.

Description

Field of TechnologyThe present invention relates to a metering device for metering bulk material, having a selectively actuatable closure. The present invention also relates to an assembly for use in such a dosing device and / or adapted to be used in such a dosing device. The invention also relates to a method for selectively actuating a closure of a metering device for metering bulk material.Prior ArtDuring the operation of a dosing device for dosing bulk material, a reliable and reliable discharge of the bulk material to be dosed is a central contact.For example, DE 41 09 089 C2 discloses a dosing device for bulk material, in which a shut-off device in the form of a helical spring is provided at the outlet of a dosing tube in which a conveying screw is located, which shut-off device prevents the bulk material from dripping when the conveying screw is at a standstill when volumetric dosing is carried out.In contrast, DE 21 08 911 A discloses a shut-off device which has a displaceable sleeve and a closure body which is fastened to the lower end of the conveying screw and is of substantially conical design.Furthermore, DE 298 02 785 U1 discloses a shut-off element for a storage container of a metering device having a tubular housing, in which a closure part having a cross section corresponding to the cross section of the tubular housing is guided displaceably along the longitudinal axis and opens up a passage opening for the bulk material as a function of the respective displacement position.Further devices for gravimetric metering of bulk materials with conveying screws are known from DE 2 412 304 A and WO 2023 / 084481A1. In this context, it is important that the bulk material enters the process downstream of the metering process in a manner that is as controlled as possible.For this purpose, on the one hand, a desired material discharge should be able to be carried out precisely. In this respect, for example, the most accurate possible dosing of the bulk material is to be achieved. On the other hand, an undesired material discharge is to be avoided as far as possible. In this respect, for example during an initial filling of the dosing device with the bulk material to be dosed, an escape of at least parts of the bulk material from the dosing device should be avoided as far as possible. Also, "dripping" of material during an interruption of a dosing process should be avoided as much as possible. This is particularly decisive in the case of batch metering, in which material discharge is carried out with cyclic interruptions.It is desirable to further improve the results of prior solutions.SUMMARY OF THE INVENTIONIt is therefore the object of the present invention to overcome the described disadvantages of the prior art and in particular to specify means which enable the most precise possible control with respect to the discharge of a bulk material to be metered.The object is achieved by the invention according to a first aspect in that a metering device for metering bulk material, having a selectively actuatable closure, has the metering deviceat least one discharge element rotatably arranged within a conveying channel for conveying the bulk material within the conveying channel along a conveying direction to at least one outlet opening of the conveying channel, wherein the discharge element has at least one shaft which is preferably arranged at the end beyond the outlet opening in the conveying direction or is connected to such a shaft, andat least one closure element movable at least between at least one operating position and at least one closure position along at least one movement path for at least regionally closing the outlet opening, wherein the shaft extends through the closure element.The invention is thus based on the surprising finding that a safe and reliable discharge of bulk material to be metered from a metering device is possible in that a gap between the discharge element and the conveying channel is kept constant. By virtue of the discharge element being mounted at the end according to the invention, the discharge element can be held in position reliably over the entire extent thereof relative to the conveying channel. In this way, contact between the discharge element and an inner surface of the conveying channel can be avoided, whereby in turn an impairment of the dosing process or even damage of parts of the dosing device can be avoided.By the shaft also extending through the closure element, the final mounting of the shaft can also be combined in combination with a closure element and the possibility associated therewith of avoiding material discharge which is undesirable in certain periods of time (for example temporarily during batch metering or during filling).As a result, the proposed metering device enables an overall improved metering process in that a desired material discharge can be carried out more precisely and at the same time an undesired material discharge can be prevented more reliably.Preferably, when a metering process with associated material discharge is or is to be carried out with the metering device, the closure element is moved into the operating position for this purpose. Preferably, if no material discharge is or is to be carried out with the metering device, the closure element is moved into the closure position for this purpose.The discharge element can be, for example, a screw and / or a spiral. For example, the windings of the worm and / or spiral can be arranged along at least a section of the shaft on the shaft.If the shaft is connected to an end, in particular in an end arranged in the region of the outlet opening, of the discharge element, preferably without a shaft in at least this end region, the end of the shaft which is not connected to the discharge element is preferably end-mounted.Preferably, a central axis of the discharge element and / or a central axis of the shaft each extends perpendicularly through a surface defined by the outlet opening and / or each extends through a center of the outlet opening.The metering device can be, for example, a differential metering scale.The metering device is particularly well suited for use in batch metering.The metering device preferably has the conveying channel. In particular, the conveying channel has a round cross section at least in sections and / or in at least one cross-sectional plane.Examples of an advantageous bulk material to be metered are rock, construction material, in particular top floor, sand, gravel and / or cement, raw materials, in particular ore, coal, clay and / or scattering salt, foods, in particular cereals, sugars, salt, coffee and / or flour, and / or pulverulent materials, in particular pigments, fillers, granules and / or pellets.The type of bulk material to be metered can be, for example, one of the following bulk material types: dust, powder, flour, grains, granules, shot, lumps, pellets and / or others.Preferably, the path of movement extends between and including the operative position and the closure position.Preferably, the movement path is predefined by the shaft and / or extends along at least one section of the shaft.The movement path can be, for example, a movement path of a center of gravity or a center point of the closure element or parts thereof (such as the retaining element and / or sealing element described in more detail below) and / or a center point of the closure element or parts thereof (such as the retaining element and / or sealing element described in more detail below) lying in a cross-sectional plane of the closure element.Alternatively or additionally, it can also be provided that the closure element has at least one sealing element which is preferably in contact with or can be brought into contact with the shaft at least when the closure element is moved into the closure position.As a result, it is reliably possible to seal the conveying channel from the environment even in the region around the shaft. As a result, a re-showering of bulk material after the termination or during the suspension of a material discharge and another escape of bulk material (for example during filling of the metering device with bulk material) can be reliably prevented or at least reduced.The sealing element can have, for example, one or more sealing lips, at least one of which of the at least one sealing lips is or can be brought into contact with the shaft, in particular at least when the closure element is moved into the closure position.Preferably, in at least one position of the closure element along the movement path, in particular in the closure position, the sealing element seals the conveying channel at least in regions, preferably completely, in a region between the shaft and the sealing element. The sealing effect between the shaft and the sealing element thereby advantageously relates to bulk materials at pressure differences between the conveying channel and the environment of between 0 mbar and 100 mbar.The environment is advantageously the region lying outside the conveying channel, which follows the outlet opening in the conveying direction.Alternatively or additionally, it can also be provided that, at least partially as a result of a position-dependent interaction between the shaft and the sealing element along the movement path, a prestress of at least parts of the sealing element along the movement path is position-dependent.The inventors have recognized that a different sealing effect between shaft and sealing element can be set at different positions along the movement path by providing a corresponding interaction. As a result, by suitable interactions, for example, a greater prestress can be set at at least one position (for example at the closure position) at which a high sealing effect is required, in comparison with at least one position (for example at the operating position) at which a lower or even no sealing effect is required and thus a lower or even no prestress can be set.Moreover, wear of the sealing element can be avoided or reduced by a position-dependent interaction, for example, in that an interaction takes place in the operating position, which interaction is associated with no or at least less (mechanical) stress on the sealing element.Preferably, the interaction between the shaft and the sealing element is a mechanical, electrical and / or magnetic interaction.The position-dependent interaction under consideration along the movement path is preferably an interaction of the same type and / or with position-dependent interaction strength.A prestress can be caused, for example, by a curvature of the sealing element or parts thereof. For example, a greater curvature of the sealing element or parts thereof can bring about a greater prestress than a comparatively less pronounced curvature of the sealing element or parts thereof (which then brings about a comparatively less great prestress).Preferably, in the sense of the present invention, a position-dependent interaction is present if, at at least one first position (and / or along at least one first section) along the movement path, an interaction of a specific type takes place between the shaft and the sealing element or parts thereof with a first interaction strength, and if, at at least one second position (and / or along at least one second section) along the movement path, an interaction of the specific type takes place between the shaft and the sealing element or parts thereof with a second interaction strength different from the first interaction strength, in particular greater or lesser. A first or second interaction strength of zero can also advantageously represent an interaction.Preferably, therefore, in the sense of the present invention, a position-dependent interaction between the shaft and the sealing element or parts thereof along the movement path is also present if an interaction of a specific type takes place at at least one first position (and / or along at least one first section) along the movement path between the shaft and the sealing element or parts thereof with a first interaction strength and if no interaction of the specific type takes place at at at least one second position (and / or along at least one second section) along the movement path between the shaft and the sealing element or parts thereof.Alternatively or additionally, it can also be provided that the sealing element, at least when the closure element is moved into the closure position, sealingly abuts at least one circumferential section of the shaft.As a result, it is reliably possible to seal the conveying channel from the environment even in the region around the shaft. As a result, a re-showering of bulk material after the termination or during the suspension of a material discharge and another escape of bulk material (for example during filling of the metering device with bulk material) can be reliably prevented or at least reduced.Alternatively or additionally, it can also be provided that the sealing element, at least when the closure element is moved into the closure position, seals the conveying channel from the environment at least in regions.The conveying channel is preferably sealed off from the environment by the sealing element when no bulk material can escape from the conveying channel through the outlet opening between the shaft and the sealing element under the typical pressure differences mentioned elsewhere in this application.Alternatively or additionally, it can also be provided that, when the closure element is moved into the closure position, the outlet opening is at least partially closed by the closure element.Preferably, at least one lower region of the outlet opening along the force of gravity is closed by the closure element.Alternatively or additionally, it can also be provided that, if the closure element is not moved into the closure position and / or at least if the closure element is moved into the operating position, the outlet opening is released by the closure element.A metering process is thus reliably possible, since material discharge can be carried out without impairment by the closure element when the closure element is in the operating position.Alternatively or additionally, it can also be provided that the movement path extends along the shaft and / or parallel to the conveying direction.For example, the movement path can run along a central axis of the shaft and / or of the discharge element.Alternatively or additionally, it can also be provided that the movement path extends from the operating position to the closure position and / or the movement path has a length of at least 0.1 cm, preferably of at least 1 cm, preferably of at least 3 cm, preferably of at least 5 cm, preferably of at least 10 cm, and / or of at most 100 cm, preferably of at most 70 cm, preferably of at most 60 cm, preferably of at most 50 cm, preferably of at most 30 cm.The closure element can thus be moved from the operating position along the movement path to the closure position. The operating position is thus a first end of the movement path and the closing position is a second end of the movement path.Alternatively or additionally, it can also be provided that the closure element extends at least in regions circumferentially around the shaft.Preferably, the closure element extends completely circumferentially around the shaft.For example, for this purpose, the closure element can be pushed onto the shaft from one end of the shaft and / or can be positioned relative to the shaft.Alternatively or additionally, it can also be provided that the shaft has an outer diameter which decreases at least in sections along the conveying direction.This advantageously makes it possible to achieve a position-dependent interaction between sealing element and shaft in a simple but nevertheless effective manner. This is because, depending on the position of the closure element, the shaft interacts with the sealing element to different extents on account of the position-dependent shaft diameter.Alternatively or additionally, it can also be provided that the shaft has an enlarged outer diameter in at least one section and wherein the sealing element interacts with this section of the shaft when the closure element is moved into the closure position.As a result, a position-dependent interaction can take place along the movement path between the shaft and the sealing element and a position-dependent prestress can thus be introduced into the sealing element.The interaction can here advantageously be a mechanical interaction, for example in that the section of the shaft with the enlarged outer diameter exerts a force on the sealing element at least partially along a radial direction (preferably at least when the closure element is moved into the closure position).Preferably, in the sense of this application, an enlarged outer diameter of the shaft can be realized, for example, by the provision of a sleeve fastened or formed on the shaft.Alternatively or additionally, it can also be provided that the shaftat least one first section in which the outer diameter of the shaft is a first outer diameter or has values within a first value range, andat least one second section, preferably following the first section in the conveying direction, in which the outer diameter of the shaft is a second outer diameter which is smaller than the first outer diameter, or values within a second value range, the upper limit of which is smaller than the lower limit of the first value range, wherein preferably the first portion and the second portion are connected to each other by a transition region.This advantageously makes it possible to achieve a position-dependent interaction between sealing element and shaft in a simple but nevertheless effective manner. This is because, depending on the position of the closure element, the shaft interacts with the sealing element to different extents on account of the position-dependent shaft diameter in the first and second sections. In other words, depending on where the closure element is located along the movement path, an interaction takes place at least in sections between the sealing element and the first or second section of the shaft.The interaction can here advantageously be a mechanical interaction at least with respect to the first section. For example, the first portion of the shaft can exert a first force on the sealing element at least partially along a radial direction (preferably at least when the closure element is moved into the closure position). Alternatively or additionally, the second section of the shaft can advantageously exert a second force on the sealing element at least partially along a radial direction (preferably at least when the closure element is moved into the operating position), which is preferably smaller than the first force. As a result, it is possible in a particularly simple manner for the prestress to be lower as a result of the interaction between the second section of the shaft and the closure element than as a result of the interaction between the first section of the shaft and the closure element.Alternatively or additionally, it can also be provided that, when the closure element is moved into the closure position, the sealing element interacts with the first section of the shaft, in particular is in contact with the first section of the shaft at least in regions.As a result, a particularly advantageous sealing of the conveying channel can be achieved during a period in which a material discharge is not provided (for example during an interruption of the material discharge or during filling of the metering device before a metering operation).Alternatively or additionally, it can also be provided that, when the closure element is moved into the operating position, the sealing element (a) does not interact with the first section of the shaft, in particular does not interact with the first section of the shaft, (b) interacts with the second section of the shaft, in particular is at least partially in contact with the second section of the shaft, and / or (c) is not in contact with the shaft.As a result, during a continuous metering process during which the shaft rotates, less friction can be achieved between the shaft and the sealing element and wear of the sealing element can thereby be reduced.Alternatively or additionally, it can also be provided that the difference in the outer diameters of the shaft in the first and second section and / or at the two positions is between 0.01 mm and 400 mm, in particular between 0.01 mm and 300 mm, in particular between 0.01 mm and 250 mm, in particular between 0.01 mm and 200 mm, in particular between 1 mm and 200 mm.It has been found to be advantageous to select the shaft diameters according to this specification. In particular, it has been recognized that even small differences in the shaft diameter lead to advantageous results.The two positions are the operating position and the closing position.Alternatively or additionally, it can also be provided that the outer diameter of the shaft in a section with which the sealing element is in contact when the closure element is moved into the closure position is greater than or equal to 4 mm, in particular greater than or equal to 5 mm, in particular greater than or equal to 10 mm, in particular greater than or equal to 30 mm, in particular greater than or equal to 50 mm, and / or less than or equal to 300 mm, in particular less than or equal to 200 mm, in particular less than or equal to 100 mm.It has been found to be advantageous to select the shaft diameters according to this specification.Alternatively or additionally, it can also be provided that the closure element has at least one retaining element, in particular at least in regions and / or in at least one cross-sectional plane of annular design, and(i) wherein the shaft extends through the retaining element, and / or(ii) wherein (a) the sealing element, in particular on an inner periphery of the holding element, is arranged at least in regions on the holding element and / or (b) the holding element has a specific inner diameter which is greater than the maximum outer diameter of the shaft along the movement path.The holding element can have in the inner region an, in particular cylindrical, recess, preferably with a circular cross section in a cross-sectional plane perpendicular to the conveying direction. As a result, an annular retaining element can be easily realized. This allows the shaft to extend through this recess and thus through the closure element. In addition, alternatively or additionally, the recess can have a diameter corresponding to the specific inner diameter and / or the sealing element can be arranged accordingly on the inner periphery of the recess.Advantageously, the holding element covers the outlet opening of the conveying channel at least in regions, in particular in an annular region, at least when the closing element is moved into the closing position.For example, the holding element can be provided concentrically to the shaft. For example, the holding element is provided concentrically to the shaft along the entire movement path.Alternatively or additionally, it can also be provided that the specific inner diameter of the holding element is smaller than or equal to the outer diameter and / or smaller than or equal to the inner diameter of the conveying channel.As a result, the holding element can advantageously cover at least a partial region of the outlet opening and thus close it, at least when the closure element is moved into the closure position. This is because, when the closure element is moved into the closure position and the retaining element is directly or indirectly in contact with the outlet opening (or an edge of the outlet opening), the transition region from the conveying channel in the direction of the environment is tapered along the conveying direction by the retaining element, whereby a regional closure of the outlet opening is possible. The remaining region of the free outlet opening can be closed by the sealing element, for example, and preferably sealed against the shaft.Alternatively or additionally, it can also be provided that the closure element is guided by means of at least one guide element, in particular at least one linear guide.This makes it possible to ensure reliable and exact positioning of the closure element along the movement path.The closure element is preferably guided by means of at least two guide elements, in particular at least two linear guides.Alternatively or additionally, it can also be provided that the closure element is movable along the movement path by actuating at least one movement device.The movement device preferably has at least one electric, at least one pneumatic and / or at least one hydraulic drive for moving the closure element along the movement path. An electric drive can be realized, for example, by a servomotor.The drive can be coupled directly or indirectly to the closure element.Alternatively or additionally, it can also be provided that the movement device has at least one cylinder, preferably at least two cylinders, each with a piston movable therein and coupled to the closure element, wherein preferably at least one, preferably all, of the one or more cylinders is configured as a pneumatic cylinder or hydraulic cylinder.In this respect, it is particularly preferred that the drive has the corresponding cylinders.For example, a cylinder and at least two linear guides can be provided in the dosing device for the feasibility of the movement of the closure element along the movement path. A movement of the closure element can then be initiated by means of the one cylinder and reliable guidance of the closure element can be realized by means of the at least two linear guides.For example, two cylinders without separate linear guides can be provided in the dosing device for the feasibility of the movement of the closure element along the movement path. Then, by means of the cylinders, both a movement of the closure element can be initiated and a reliable guidance of the closure element can be realized.Alternatively or additionally, it can also be provided that a central axis of the at least one cylinder, a central axis of the shaft and a central axis of the conveying channel run parallel to one another and / or which run within a common sectional plane of the metering device.Preferably, the shaft is arranged concentrically to the conveying channel. Then, the central axis of the shaft and the central axis of the conveying channel are preferably identical.Alternatively or additionally, it can also be provided that the metering device has at least one bearing unit by means of which the shaft is end-mounted, wherein the bearing unit preferably has or forms at least one rolling bearing and / or at least one sliding bearing.By means of the bearing unit, a reliable positioning of the shaft relative to the conveying channel and the closure element can be achieved. As a result, the metering process can be carried out more reliably and undesired discharge of material from the conveying channel can be avoided.Alternatively or additionally, it can also be provided that the dosing device has at least one vertical ejection and wherein the outlet opening opens into the vertical ejection and / or the movement path of the closure element extends, preferably completely, within the vertical ejection.By means of the vertical discharge, the discharged material can be reliably and reliably supplied to a process downstream of the metering process.A central axis of the vertical ejection can advantageously extend perpendicular to the conveying direction and / or parallel to the force of gravity.Alternatively or additionally, it can also be provided that the dosing device has at least one fastening plate, which is preferably designed in the manner of a flange, and preferably the bearing unit and / or the at least one cylinder of the movement device are each at least partially inserted through openings in the fastening plate and / or fastened to the fastening plate.The fastening plate thus enables a secure provision of the components arranged thereon.Alternatively or additionally, it can also be provided that the positioning of the bearing unit and the at least one cylinder relative to one another is fixed or fixable by the fastening plate.This allows reliable use of the closure.Alternatively or additionally, it can also be provided that an assembly which is designed to be detachable as a whole from the dosing device has at least the at least one cylinder of the movement device, the closure element, the bearing unit and the fastening plate.Such a modular construction makes it possible to easily provide components involved in the closure on the metering device and also to exchange them quickly and reliably if necessary. As a result, retrofitting of existing metering devices with a closure according to the invention is relatively easily possible. And in the event of an exchange, downtime of the dosing device can be avoided or at least reduced.The assembly can advantageously also have the pistons provided within the at least one cylinder.Alternatively or additionally, it can also be provided that the fastening plate has elongated holes for fastening the assembly to the dosing device, in particular to a housing section of the vertical ejection device, and / or for fine alignment of the assembly relative to the shaft and / or the conveying channel along at least two dimensions.As a result, an alignment of the components of the assembly relative to other components of the metering device (in particular the shaft, the discharge element and / or the conveying channel) can be carried out using simple but effective means.Alternatively or additionally, it can also be provided that at least some of the components of the assembly provided within the vertical discharge, in particular at least the bearing unit and / or the closure element, are inserted or insertable into the vertical discharge through an opening in the housing of the vertical discharge, and the fastening plate is fastened or can be fastened to the housing section while at least partially covering the opening.This allows simple insertion and simple removal of the assembly.Alternatively or additionally, it can also be provided that the sealing element is configured annularly, for example as a sealing ring, in particular as a radial shaft sealing ring.As a result, the shaft can be surrounded by the sealing element particularly easily along its entire circumference.Alternatively or additionally, it can also be provided that the sealing element comprises PTFE and / or silicone as material.These materials are particularly preferred because they are inexpensive to produce and reliably have a sealing effect.Alternatively or additionally, it can also be provided that at least one sealing element is provided on the closure element, in particular on the retaining element, preferably on an end face of the retaining element facing the outlet opening, which sealing element can be brought into contact with an end face of the conveying channel, in particular with an edge of the outlet opening, and / or which, at least when the closure element is moved into the closure position, is in contact with the conveying channel, in particular with an edge of the outlet opening.The sealing element is advantageous for the axial sealing of a region between the conveying channel and the closure element.The sealing element can be used to seal the contact region of the conveying channel and the closure element. The conveying channel can thus advantageously also be sealed off from the environment in regions away from the shaft (where a sealing effect is preferably taken over by the sealing element).Preferably, the sealing element does not have a radial sealing component, in particular no cone.In an advantageous embodiment, the holding element, the sealing element and the sealing element are formed in one piece, in particular from PTFE. As a result, both a radial and an axial seal can be achieved very easily and reliably.Alternatively or additionally, it can also be provided that on an end face of the conveying channel, in particular on an edge of the outlet opening, a sealing element is provided which can be brought into contact with the closure element, in particular the retaining element, and / or which, at least when the closure element is moved into the closure position, is in contact with the closure element, in particular the retaining element.The sealing element is advantageous for the axial sealing of a region between the conveying channel and the closure element.The sealing element can be used to seal the contact region of the conveying channel and the closure element. The conveying channel can thus advantageously also be sealed off from the environment in regions away from the shaft (where a sealing effect is preferably taken over by the sealing element).Preferably, the sealing element does not have a radial sealing component, in particular no cone.Alternatively or additionally, it can also be provided that the selectively actuatable closure enables sealing of the conveying channel for bulk material against pressure differences of between 0 mbar and 100 mbar. Preferably, the pressure difference is related to the pressure differences between the conveying channel and the environment.Alternatively or additionally, it can also be provided that the dosing device has at least one receiving unit for receiving the bulk material to be dosed and / or at least the one conveying channel into which the bulk material can be displaced out of the receiving unit.As a result, the bulk material to be metered can be reliably kept available and can be fed to the conveying channel during the metering process. For example, the bulk material can be displaceable from the receiving unit via a connecting channel into the conveying channel.The object is achieved by the invention according to a second aspect in that an assembly for use in a dosing device according to the first aspect of the invention and / or which is adapted to be used in a dosing device according to the first aspect of the invention, wherein the assembly has at least one fastening plate and wherein the assemblyat least one closure element for selectively closing an outlet opening of a conveying channel of the metering device, having a discharge element, which can be rotatably arranged within the conveying channel, for conveying bulk material within the conveying channel along a conveying direction toward the outlet opening of the conveying channel,at least one cylinder of at least one movement device for at least indirectly moving the closure element along a movement path running parallel to the central axis of the conveying channel, andat least one bearing unit for the final mounting of a shaft connected to the discharge element or exhibited by the latter, which can be provided together with the fastening plate as a whole, is proposed.The assembly may preferably correspond to the assembly as described with respect to the dosing device according to the first aspect of the invention.All advantages which have been described with respect to the metering device according to the first aspect of the invention (and in particular with respect to the subassembly therein) apply here correspondingly also to the subassembly according to the second aspect of the invention. Therefore, reference can be made to the previous statements at this point.The features which have been described with respect to the assembly of the metering device according to the first aspect of the invention can also be provided correspondingly in the assembly according to the second aspect of the invention, individually and in any combination, unless the context reveals otherwise.In particular, the physical and functional configurations of the individual parts of the subassembly described in connection with the metering device according to the first aspect of the invention (in particular the closure element, the movement device, the fastening plate and the bearing unit) and the described structural and functional relationships between the individual parts of the subassembly described there and the metering device (for example between the sealing element and the shaft) can also be provided correspondingly in the subassembly according to the second aspect of the invention, individually and in any combination, unless the relationship reveals otherwise.The object is achieved by the invention according to a third aspect in that a method for selectively actuating a closure of a metering device for metering bulk material, in particular a metering device according to the first aspect of the invention, the method comprising at least one closure element being moved from the operating position into the closure position along at least one movement path extending between at least one operating position and at least one closure position, wherein in the closure position an outlet opening of a conveying channel in which a rotatably arranged discharge element for conveying the bulk material within the conveying channel along a conveying direction towards the outlet opening of the conveying channel is provided is closed at least in regions by means of the closure element, wherein the discharge element is closed at least one shaft which is arranged at the end beyond the outlet opening in the conveying direction, having or being connected to such a shaft, and wherein the shaft extends through the closure element, wherein preferably the closure element has at least one sealing element, and in particular the shaft and the sealing element interact with one another along the movement path depending on the position and at least partially thereby a prestress of at least parts of the sealing element is set along the movement path depending on the position is proposed.All the advantages which have been described with respect to the metering device according to the first aspect of the invention apply here correspondingly also to the method according to the third aspect of the invention. Therefore, reference can be made to the previous statements at this point.The features which have been described with respect to the metering device according to the first aspect of the invention can also be provided correspondingly in the method, individually and in any combination, unless the context indicates otherwise.In particular, the physical and functional configurations of the individual parts described in connection with the dosing device according to the first aspect of the invention and the described structural and functional relationships between the individual parts can also be provided correspondingly in the method, individually and in any combination, unless the relationship reveals otherwise.Alternatively or additionally, it can also be provided that during a period in which the closure element is moved, the shaft is not rotated or the shaft is rotated at a lower rotational speed than during a period in which the closure element is in the operating position and / or in which bulk material is applied from the outlet opening with the metering device.As a result, the wear of the sealing element can be reduced, in particular if the interaction between the shaft and the sealing element is greater than at periods in which the closure element is in the operating position.Brief Description of the DrawingsFurther features and advantages of the invention are evident from the following description, in which preferred embodiments of the invention are explained with reference to schematic drawings.The following are shown: FIG. 1 a shows a schematic perspective sectional view of a dosing device according to the first aspect of the invention in a first configuration; FIG. 1 b shows a schematic perspective sectional view of the dosing device from FIG. 1 a in a second configuration; FIG. 2 shows an enlarged illustration of a detail from FIG. 1 b; FIG. 3 is a schematic perspective sectional view of an assembly according to the second aspect of the invention; and FIG. 4 is a flow chart of a method according to the third aspect of the invention.DESCRIPTION OF THE EMBODIMENTSFIG. 1 ashows a schematic perspective sectional view of a dosing device 1 for dosing bulk material according to the first aspect of the invention in a first configuration. FIG. 1 bshows a schematic perspective sectional view of the dosing device 1 in a second configuration.The dosing device 1 has a discharge element 5 rotatably arranged within a conveying channel 3 of the dosing device 1 (in FIGS. 1 aand 1 b, the conveying channel 3 and the discharge element 5 are cut off on the right). By means of the discharge element 5, bulk material can be conveyed within the conveying channel 3 along a conveying direction R to at least one outlet opening 7 of the conveying channel 3. The outlet opening 7 opens into a vertical discharge 9 of the metering device 1. as a result, the bulk material can be discharged in metered fashion (for example by means of differential metering technology if the metering device 1 is a differential metering scale) from the conveying channel 3 and fed via the vertical discharge 9 to a downstream process.The discharge element 5, which is designed as a worm in the present case, has a shaft 11 which is mounted at the end beyond the outlet opening 7 in the conveying direction R by means of a bearing unit 13. In the present case, windings of the worm are arranged on a section of the shaft 11. In embodiments, however, the discharge element itself does not have a shaft, but is connected to such a shaft.Due to the end mounting of the shaft 11, a reliable and exact positioning of the discharge element 5 relative to the conveying channel 3 (in particular such that the central axes of the two parts 3 and 5 coincide) is possible. In this way, a gap 15 between the discharge element 5 and the conveying channel 3 can be kept constant along the entire extension of the conveying channel 3, even and just while the discharge element 5 rotates within the conveying channel 3. This allows the metering process to be improved. In contrast, in the case of a floating mounting of the discharge element, the free end of the discharge element can come into contact with an inner wall region of the conveying channel 3 for example on account of oscillations. This can lead to adverse effects on the metering process and also to damage to the metering device 1 or undesired material abrasion or wear.The shaft 11 has a decreasing outer diameter along the conveying direction R. In this respect, the shaft 11 has a first section 17 in which the outer diameter of the shaft 11 is a first outer diameter D 1. In addition, the shaft 11 has a second section 19 following the first section 17 in the conveying direction R, in which the outer diameter of the shaft 11 is a second outer diameter D 2 which is smaller than the first outer diameter D 1. The first section 17 and the second section 19 are connected to one another by a transition region 21.The dosing device 1 also has a closure element 23 with a holding element 25 (which is configured annularly in a cross-sectional plane perpendicular to the conveying direction). A sealing element 29 in the form of a radial shaft sealing ring is arranged on an inner periphery 27 of the holding element 25. The closure element 23 (in particular the parts holding element 25 and sealing element 29) extends circumferentially around the shaft 11 in this case, or, stated differently, the shaft 11 extends through the closure element 23 (in particular through the holding element 25 and the sealing element 29).The closure element 23 can be moved between an operating position and a closure position along a movement path which runs parallel to the conveying direction R and is illustrated as a dashed line in FIGS. 1 aand 1 b.In the first configuration shown in FIG. 1 a, the closure element 23 is moved into the operating position, that is to say to the left in FIG. 1 a. When the closure element 23 is moved into the operating position, the outlet opening 7 is released by the closure element 23 and bulk material can be discharged from the outlet opening 7 as described above. In the second configuration shown in FIG. 1 b, the closure element 23 is moved into the closure position, that is to say to the right in FIG. 1 b. When the closure element 23 is moved into the closure position, the outlet opening 7 is closed by the closure element 23.Due to the varying outer diameter of the shaft 11 along the movement path, a position-dependent interaction occurs between the shaft 11 and the sealing element 29 along the movement path.When the closure element 23 is moved into the operating position (FIG. 1 a), the sealing element 29 interacts with the second section 19 of the shaft 11. More precisely, the sealing element 29 is then in contact with the second portion 19 of the shaft. In embodiments, when the closure member 23 is moved to the operating position, the sealing member 29 may not be in contact with the shaft 11 either.When the closure element 23 is moved into the closure position (FIG. 1 b), the sealing element 29 interacts with the first section 17 of the shaft 11. More precisely, the sealing element 29 is then in contact with the first section 17 of the shaft 11.Depending on which section of the shaft 11 is in contact with the sealing element 29, the contact between the shaft 11 and the sealing element 29 leads to a different prestress of the sealing element 29.Therefore, when the closure element 23 is moved into the operating position shown in FIG. 1 a, the sealing element 29 has a lower prestress than when the closure element 23 is moved into the closure position shown in FIG. 1 b. Due to the lower prestress of the sealing element 29 in the operating position, wear of the sealing element 29 during a rotational movement of the shaft 11 (therefore while material is being discharged from the conveying duct 3 through the outlet opening 7) can be reduced in this configuration. Due to the greater prestress of the sealing element 29 in the closed position, in this configuration, a discharge of material (for example a "dripping" of material during an interruption of the material discharge) from the outlet opening 7 in the region between the holding element 25 and the shaft 11 (i.e. where the sealing element 29 is arranged) can be reliably prevented.The remaining region of the outlet opening 7 is closed by the holding element 25 in the closed position. Since the inner diameter of the holding element 25 is smaller than the inner diameter of the conveying channel 3, an end face 31 of the holding element 25 facing the outlet opening 7 (or any parts arranged thereon) can serve as a closing surface. However, since the inner diameter of the holding element 25 is selected to be larger than the maximum outer diameter of the shaft 11 along the movement path, the closure element 23 can be displaced along the movement path without it being "seated" on the shaft 11.On the holding element 25, a sealing element 33 is provided on the end face 31 of the holding element 25 facing the outlet opening 7. The sealing element 33 is in contact with an edge of the outlet opening when the closure element 23 is moved into the closure position. In embodiments, the sealing element 33 can alternatively or additionally also proceed on an end face of the conveying channel 3 facing the closure element 23.FIG. 2 shows an enlarged illustration of a figure detail highlighted in FIG. 1 b with a dashed border. It is particularly good in this case that, as a result of the interaction between the first section 17 of the shaft 11 and the sealing element 29, there can be seen curved sealing element 29 which is therefore prestressed to a greater extent (than in the operating position).Thus, by the shaft 11 extending through the closure element 23, as described, an end-mounted shaft 11 in combination with a selectively actuatable closure of the outlet opening 7 can advantageously be provided in the dosing device 1.In an advantageous embodiment, the holding element 25, the radially acting sealing element 29 and the axially acting sealing element 33 can also be formed in one piece, in particular from PTFE.The dosing device 1 further comprises a receiving unit, not shown in the figures, for receiving the bulk material to be dosed. From this receiving unit, the bulk material can be displaced into the conveying channel 3.The dosing device 1 (see FIGS. 1 aand 1 b ) also has a movement device 35. The closure element 23 can be moved along the movement path with the movement device 35. Two cylinders 37 are provided in each cylinder 37, a piston 39 movable therein, which is coupled to the closure element 23, respectively. By synchronously displacing the pistons 39 within the cylinders 37, the closure element 23 is displaceable along the movement path. Each cylinder 37 thus simultaneously also implements a linear guide for the closure element 23.The central axes of the two cylinders 37, the central axis of the shaft 11 and the central axis of the conveying duct 3 run parallel to one another and lie within the plane of the drawing of FIGS. 1 aand 1 b.The bearing unit 13 and the two cylinders 37 of the movement device 35 are each inserted through openings in a flange-like fastening plate 41 of the dosing device 1 and fastened to the fastening plate 41. As a result, the positioning of the bearing unit 13 and the two cylinders 37 relative to each other is fixed by the fastening plate 41.The two cylinders 37 (including the piston 39) of the movement device 35, the closure element 23, the bearing unit 13 and the fastening plate 41 are comprised of an assembly 43 which is formed as a whole so as to be detachable from the dosing device 1.FIG. 3 shows a schematic perspective sectional view of the assembly 43. the assembly 43 can be an assembly according to the second aspect of the invention.Due to the advantageous connection of the components of the assembly 43 to one another, it is precisely the closure element 23 that can be inserted into the vertical discharge 9 in a very reliable and simple manner through an opening in the housing of the vertical discharge 9. The fastening plate 41 then covers the opening in the assembled state. Fastening of the fastening plate 41 to the housing is possible very easily and reliably by means of the elongated holes 45 provided in the fastening plate 41. The slots 45 also make it possible to finely align the assembly 43 relative to the shaft 11 and the conveying channel 3 along two dimensions (in FIGS. 1 aand 1 b, these are the directions "front-rear" perpendicular to the plane of the drawing of the figures and "bottom-top" within the plane of the drawing of the figures).FIG. 4 shows a flow diagram 100 of a method according to the third aspect of the invention.With the method, in a metering device for metering bulk material (like the metering device 1), an outlet opening of a conveying channel, in which a rotatably arranged discharge element for conveying bulk material is provided within the conveying channel along a conveying direction towards the outlet opening of the conveying channel, can be closed at least in regions. The discharge element has at least one shaft which is end-mounted beyond the outlet opening in the conveying direction or is connected to such a shaft, and wherein the shaft extends through the closure element.In 101, at least one closure element, which has a sealing element, is moved from the operating position into the closure position along at least one movement path extending at least between at least one operating position and at least one closure position.In 103, the shaft and the sealing element interact with one another along the movement path as a function of position, and as a result at least in part a prestress of at least parts of the sealing element along the movement path is set as a function of position. The interaction can be effected, for example, by different shaft diameters.In 105, the outlet opening is closed by means of the closure element in the closure position.The features disclosed in the preceding description, in the drawings and in the claims can be essential for the invention in its various embodiments both individually and in any combination.List of reference characters1 Metering device 3 Conveying channel 5 Discharge element 7 Outlet opening 9 Vertical discharge 11 Shaft 13 Bearing unit 15 Gap 17 First section Shaft (D 1) 19 Second section Shaft (D 2) 21 Transition region 23 Closure element 25 Holding element 27 Inner periphery of the holding element 29 Sealing element / sealing lip with radial sealing effect 31 End face 33 Sealing element with axial sealing effect 35 Movement device 37 Cylinder 39 Piston 41 Fastening plate 43 Assembly 45 Elongated hole 100 Flow chart 101 Movement of a closure element from an operating position into a closure position along a movement path 103 Position-dependent interaction between a shaft and a sealing element along the movement path 105 Closure of an outlet opening by means of the closure element D 1 First outer diameter D 2 Second external diameter R conveying direction

Claims

Metering device for metering bulk material, having a selectively actuatable closure, the metering device having - a discharge element which is rotatably arranged within a conveying channel and is intended for conveying the bulk material within the conveying channel along a conveying direction toward an outlet opening of the conveying channel, wherein the discharge element has a shaft which is arranged at the end beyond the outlet opening in the conveying direction or is connected to such a shaft, and - a closure element which can be moved between an operating position and a closure position along a movement path and is intended for at least regionally closing the outlet opening, wherein the shaft extends through the closure element.The dosing device according to claim 1, wherein the closure element comprises at least one sealing element which, at least when the closure element is moved into the closure position, is or can be brought into contact with the shaft.The dosing device according to claim 2, wherein at least partly due to a position dependent interaction between the shaft and the sealing element along the movement path a prestress of at least parts of the sealing element along the movement path is position dependent.The dosing device according to any one of claims 2 to 3, wherein the sealing element, at least when the closure element is moved into the closure position, sealingly abuts at least one circumferential portion of the shaft.The metering device according to any one of the preceding claims, wherein the movement path runs along the shaft and / or parallel to the conveying direction.The metering device according to one of the preceding claims, wherein the closure element extends at least in regions circumferentially around the shaft.Metering device according to one of the preceding claims, wherein the shaft has an outer diameter which decreases at least in sections along the conveying direction.The dosing device according to any one of claims 2 to 7, wherein the shaft has an enlarged outer diameter in at least one portion and wherein the sealing element interacts with this portion of the shaft when the closure element is moved into the closure position.The metering device according to any one of the preceding claims, wherein the shaft comprises - at least one first section in which the outer diameter of the shaft is a first outer diameter or has values within a first value range, and - at least one second section, which follows the first section in the conveying direction and in which the outer diameter of the shaft is a second outer diameter which is smaller than the first outer diameter, or values within a second value range whose upper limit is smaller than the lower limit of the first value range, wherein the first section and the second section are connected to one another by a transition region.The dosing device of claim 9, wherein when the closure member is moved to the closure position, the sealing member interacts with the first portion of the shaft.The dosing device according to any one of claims 9 to 10, wherein when the closure element is moved into the operating position, the sealing element (a) does not interact with the first portion of the shaft, (b) interacts with the second portion of the shaft and / or (c) is not in contact with the shaft.The metering device according to any one of the preceding claims, wherein the closure element has at least one retaining element which is formed annularly at least in regions and / or in at least one cross-sectional plane, and (i) wherein the shaft extends through the retaining element and / or (ii) wherein (a) the sealing element is arranged at least in regions on the retaining element and / or (b) the retaining element has a specific inner diameter which is greater than the maximum outer diameter of the shaft along the movement path.The dosing device according to any one of the preceding claims, wherein the closure element is movable along the movement path by actuating at least one movement device.The dosing device according to claim 13, wherein the movement device comprises at least one cylinder with a piston movable therein and coupled to the closure element, wherein the cylinder is configured as a pneumatic cylinder or hydraulic cylinder.The metering device according to any one of the preceding claims, wherein the metering device has at least one bearing unit by means of which the shaft is end-mounted, wherein the bearing unit has or forms at least one rolling bearing and / or at least one sliding bearing.Metering device according to one of Claims 2 to 15, wherein the sealing element is configured annularly as a sealing ring.Assembly for use in a dosing device according to one of the preceding claims and / or which is adapted to be used in a dosing device according to one of the preceding claims, wherein the assembly has at least one fastening plate and wherein the assembly has - at least one closure element for selectively closing an outlet opening of a conveying channel of the dosing device with a discharge element which can be arranged rotatably within the conveying channel for conveying bulk material within the conveying channel along a conveying direction towards the outlet opening of the conveying channel, - at least one cylinder of at least one movement device for at least indirectly moving the closure element along a movement path running parallel to the central axis of the conveying channel, and - at least one bearing unit for the end mounting of a shaft which is connected to the discharge element or is exhibited by it and which can be provided together with the fastening plate as a whole.Method for selectively actuating a closure of a metering device for metering bulk material according to one of Claims 1 to 16, the method having the fact that at least one closure element is moved from the operating position into the closure position along at least one movement path which extends at least between at least one operating position and at least one closure position, wherein, in the closure position, an outlet opening of a conveying channel in which a rotatably arranged discharge element for conveying the bulk material within the conveying channel along a conveying direction towards the outlet opening of the conveying channel is provided is closed at least in regions by means of the closure element, wherein the discharge element has at least one shaft which is arranged at the end beyond the outlet opening in the conveying direction or is connected to such a shaft, and wherein the shaft extends through the closure element.

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