Abstract:
A metering device for metering bulk materials comprises a flap and an insert, in which the flap can be pivoted in the insert, and wherein the flap can be subjected to vibrations. The insert is dimensionally stable while the flap vibrates, in which it is possible to prevent deformations of the insert during the vibration of the flap. The design of the flap therefore can be adapted to the insert without risking that parts of the flap, e.g., an edge of a disk rub against the insert. The abrasion of the material of the insert, as well as the contamination of the bulk material, can be prevented in this fashion during the vibration of the flap. Therefore, the insert is also subjected to fewer mechanical stresses such that its service life is relatively long.

Description:
FIELD OF THE INVENTION  
       [0001]    Embodiments of the present invention relate to a metering device, and more particularly to a metering devices used for metering various bulk materials without contamination, in different technical fields. 
       BACKGROUND OF THE INVENTION  
       [0002]    Bulk materials are decanted in many industrial processes such as, for example, in various processes in the food industry, agriculture, the chemical industry or the pharmaceutical industry. In this context, the term “bulk material” refers to a pourable agglomeration of particles that are small in relation to the overall quantity of the bulk material. Under certain circumstances, a bulk material may behave as a fluid, particularly after exceeding an activation energy. In this case, the particles essentially remain preserved or do not significantly change their shape on the transport path, respectively. Among other things, the term bulk materials also includes, in particular, construction materials such as, for example, sand, pebbles, gravel or cement; mineral goods such as, for example, ore or de-icing salt; foods such as, for example, grains (rice, wheat, etc.), sugar, table salt, coffee or flour; powdery goods such as, for example, pigments or pharmaceutical substances; fillers; granulates and pellets such as, for example, pills, iron ore pellets or pressed animal feed. 
         [0003]    When decanting bulk materials, it is common practice to utilize metering devices that frequently comprise a flap that is arranged in a pivotable fashion in a pipe section or the like. When the flap is closed, the inside of the pipe section is blocked such that essentially no bulk material can any longer flow through the pipe section. The bulk material source is frequently positioned above the bulk material destination such that the decanting of the bulk material can be realized with the aid of the gravitational force. In such an arrangement, the decanting is simply realized by opening the flap such that the bulk material can flow through the pipe section. The flap is closed again once the desired quantity of bulk material has been decanted. In contrast to liquids or gases, bulk materials typically do not begin to flow continuously when the flap is opened, but rather start flowing in relatively large quantities after an activation energy is exceeded such that metering devices of this type are not able to precisely meter relatively small quantities of bulk material. When the flap is closed, the flow of bulk material also cannot be simply reduced in a continuous fashion such that a relatively precise metering of the quantity of decanted bulk material also cannot be realized with such a metering device. 
         [0004]    WO 01/75342 A1 describes a metering device that comprises an insert of elastically deformable material that is positioned in a pipe section and a flap with a disk and two journals. The flap is supported in the insert in a pivotable fashion with the aid of the journals that are arranged in two openings of the insert. The metering device furthermore features a pivoting mechanism that serves for pivoting the flap and engages on one of the journals, as well as a vibrating mechanism that engages on both journals and serves for vibrating the flap. During the operation of this device, the flap is opened from a closed position by means of the pivoting mechanism and simultaneously vibrated by means of the vibrating mechanism in order to decant the bulk material. These vibrations make it possible to overcome the activation energy required for initiating the flow of the bulk material when relatively small flap openings are used such that relatively small quantities of bulk material or relatively precise quantities of bulk material can be metered. The elastic deformation of the insert during the absorption of the flap vibrations and during the pivoting of the flap causes the disk of the flap to rub against the insert such that the material of the insert typically is abraded continuously. This material contaminates the bulk material and therefore significantly affects the decanted bulk material, particularly in the food industry, the chemical industry and the pharmaceutical industry. This material abrasion also reduces the service life of the insert, wherein the thusly required frequent replacement of the insert can be quite costly. The installation of this metering device is also complicated because the flap needs to be respectively pulled over the insert that is stretched with the aid of an external force. 
         [0005]    In view of the foregoing, it would be desirable to provide an improved device for metering bulk materials, which does not contaminate the bulk materials. 
       DISCLOSURE OF THE INVENTION  
       [0006]    Embodiments of the present invention relate to a metering device for metering bulk materials without contaminating them. 
         [0007]    According to an embodiment of the present invention, a metering device for metering bulk materials is provided. The metering device includes a flap and an insert. The flap is pivoted in the insert, which allows for vibrations. Depending on the pivoting position of the flap, the insert may be closed or more or less open. When the flap is open, the activation energy required for initiating the flow of the bulk material can be overcome due to the vibrations of the flap such that a bulk material flow with a small flow volume can be realized and the bulk material therefore can be metered in a relatively accurate fashion. 
         [0008]    In an embodiment of the present invention, the flap is supported in the insert in such a way that the insert essentially is dimensionally stable while the flap vibrates. Such an elastic vibratory support of the flap makes it possible to prevent the insert from deforming while the plate vibrates. The design of the flap therefore can be adapted to the insert without risking that parts of the flap such as, for example, an edge of the disk rub against the insert. This prevents the material of the insert from being abraded during the vibration of the flap and, if applicable, from contaminating the bulk material as it is particularly critical, for example, with bulk materials consisting of foods or medications. In addition, the insert of a thusly designed metering device is subjected to significantly fewer mechanical stresses such that it has a relatively long service life. 
         [0009]    In accordance with an embodiment of the present invention, the metering device features a housing, in which the insert and the flap are arranged. In this case, the housing as well as the insert are typically realized in a tubular fashion such that the insert forming the inner pipe tightly adjoins the housing forming the outer pipe. The housing can preferably be connected to a bulk materials source and a bulk material destination in such a way that the bulk material is able to flow through the insert and to pass the flap when the flap is open. On the side that faces the bulk material source and the side that faces the bulk material destination, the insert may be respectively provided with a seal such as, for example, a ring seal in order to realize a tight connection between the insert and the bulk material source and the bulk material destination, respectively. 
         [0010]    In an embodiment of the present invention, the insert is preferably made of a relatively strong and relatively hard material. In this context, the term strong refers to a material property that describes the mechanical resistance of the material to a change in shape. The term hard refers to the mechanical resistance of a body to the penetration of another body. An insert of such a material with relatively high strength and hardness allows a simple design of the support of the flap in the insert such that the insert is dimensionally stable while the flap vibrates. Due to its preferred wear characteristics, the insert can also have a relatively long service life. It is furthermore preferred to manufacture the insert of a plastic that is generally recognized as safe for handling foods and medications, particularly a plastic approved by the United States Food and Drug Administration (FDA). It may be manufactured, for example, of polyoxymethylene (POM), particularly of polyoxymethylene copolymer (POM-C). 
         [0011]    In accordance with an embodiment of the present invention, the metering device includes at least one elastically deformable vibration element and the flap features at least one journal that is supported in the insert and a disk. The vibration element is arranged around the journal between the journal and the insert. During the operation, the vibrational movements of the flap and, in particular, its journal are absorbed by the vibration element such that essentially no vibrational movements are transmitted to the insert during the vibration of the flap and the insert, in essence, is not correspondingly deformed or moved. The vibration means typically can be easily replaced if they are worn out to such a degree that their proper function can no longer be ensured after a certain period of use. The wear of the insert therefore can be significantly reduced such that it has to be replaced less frequently. 
         [0012]    In an embodiment of the present invention, the vibration element may be realized in the form of a ring, wherein the journal protrudes through the ring. It may be manufactured of any elastically deformable material or be realized in any elastically deformable shape. For example, it may be manufactured of silicone or silicone and polytetrafluor ethylene (PTFE), particularly in the form of a silicone-PTFE ring. The flap typically features two journals that are arranged on the disk opposite of one another and lie on a common axis, about which the flap can be pivoted. In this case, one respective vibration element is preferably arranged around each journal, wherein it is particularly preferred to respectively arrange two or more vibration elements around both journals such that they are offset relative to one another in the direction of the pivoting axis of the flap. In such an arrangement, the vibrational movements of the flap can be absorbed by the vibration elements and the flap is essentially prevented from tilting during its pivoting movement such that the disk is not pressed against or into the insert, respectively. 
         [0013]    In an embodiment of the present invention, the elastically deformable vibration element preferably features an anti-friction layer on its inner side. This anti-friction layer allows a low-friction movement of the journal or the journals in the vibration element or in the vibration elements during the pivoting of the flap. This makes it possible to pivot the flap with a relatively low expenditure of force. The anti-friction layer may consist, for example, of PTFE. It may furthermore be realized, for example, in the form of a ring with a concave radial outer side for receiving the elastically deformable ring and with a flat inner side. 
         [0014]    In an embodiment of the present invention, the metering device acts upon the vibration element with a seal gas. This makes it possible to ensure that no bulk material or dust fractions thereof escape laterally at the flap. 
         [0015]    In an embodiment of the present invention, the metering device features a gap between the insert and the disk when the flap is in a closed position in the insert. Due to the dimensionally stable design of the insert, the gap may be so small that the insert can be closed with the flap in a dust-tight fashion and the disk, in essence, is simultaneously prevented from rubbing against the insert. 
         [0016]    In an embodiment of the present invention, the insert includes a first part, a second part and connecting means. The first part and the second part are separably connected to one another with the aid of the connecting means in this case, and the journal is supported between the first part and the second part. The connecting means used may consist, for example, of at least one screw that extends through corresponding holes in both parts of the insert and is fastened, for example, by means of a nut. In a thusly designed metering device, the insert can be easily disassembled in order to remove the flap and the vibration elements. A seal that is realized, for example, in an annular fashion may be arranged between the two parts in order to seal the connection between these two parts of the insert. 
         [0017]    In an embodiment of the present invention, the metering device preferably features a pivoting mechanism that is connected to the at least one journal, wherein an elastomer coupling is arranged between journal and the pivoting mechanism. Such a pivoting mechanism makes it possible to turn the journal about its longitudinal axis such that the disk is simultaneously pivoted. The elastomer coupling may be realized, in particular, in the form of an elastomer claw coupling and produces a movable connection between the pivoting mechanism and the flap such that the vibrational movements of the flap are not substantially impaired by the pivoting mechanism. 
         [0018]    In an embodiment of the present invention, the pivoting mechanism preferably features a pneumatic linear drive for pivoting the flap. In this case, one end of the linear drive preferably is rotatably connected to the insert in a stationary fashion, for example, by means of the housing, wherein the other side of the linear drive is connected to the elastomer coupling by means of a lever. In comparison with widely used rotary drives, such a linear drive makes it possible to quickly and reliably pivot the flap. In addition, such a pneumatic linear drive can be controlled in an easily reproducible fashion with the aid of a suitable circuit. 
         [0019]    In an embodiment of the present invention, the metering device features a vibration mechanism with an eccentric rotor and rotating means. In this case, the rotor is rotatably arranged on a pivoting axis of the flap and the rotor vibrates the flap when the rotating means turn the rotor. The rotating means used may consist, for example, of a pressurized gas, particularly compressed air that acts upon the rotor via correspondingly configured lines in the metering device. In a flap with two journals, the vibration mechanism may be arranged in one of the two journals or preferably in both journals. 
         [0020]    The foregoing and other features, aspects, and advantages of the present invention will be more apparent from the following detailed description, which illustrates exemplary embodiments of the present invention. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0021]    For a better understanding of the present invention, reference is made to the following description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which: 
           [0022]      FIG. 1  is a side view of a metering device, in accordance with an embodiment of the present invention. 
           [0023]      FIG. 2  is a horizontal projection of the metering device according to  FIG. 1 , in which the flap is pivoted into a closed position, in accordance with an embodiment of the present invention. 
           [0024]      FIG. 3  is an exploded side view of the components of the metering device according to  FIG. 1 , in accordance with an embodiment of the present invention. 
           [0025]      FIG. 4 , a cross section through the metering device along the line A-A in  FIG. 2 , wherein the flap is pivoted into an open position, in accordance with an embodiment of the present invention. 
           [0026]      FIG. 5 , a partially exploded view of certain components of the cross section according to  FIG. 4 , in accordance with an embodiment of the present invention. 
           [0027]      FIG. 6 , an exploded view of certain components of the cross section according to  FIG. 4 , in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0028]    Certain terms are used for practical reasons in the following description and should not be interpreted in a restrictive sense. The words “right,” “left,” “bottom” and “top” refer to the corresponding directions in the figures. The terms “inward” and “outward” refer to directions extending toward or away from the geometric center of the metering device, as well as designated components thereof. The terminology includes the words expressly mentioned above, derivations thereof and words with similar meaning. 
         [0029]      FIG. 1  shows an embodiment of an inventive metering device that comprises a housing  1  with a pipe section  11  and a mounting part  13 . A flange  12  is respectively connected to the top and to the bottom of the pipe section  11  and outwardly protrudes over the pipe section  11 . A receptacle  26  that is stationarily connected to the first longitudinal end of a pneumatic cylinder  21  of a pivoting mechanism  2  is rotatably mounted on the mounting part  13  of the housing  1  by means of a mounting pin  25 . A piston  22  protrudes from the second longitudinal end of the cylinder  21  and is rotatably connected to the lever  31  of a drive coupling  3  by means of a fork  23  and a mounting pin  27 . The fork  23  and the lever  31  collectively form a joint that can be turned about the mounting pin  27 . The lever  31  ends in a connecting bearing  32  that is mounted on a projection  33  rigidly connected to the housing  1 . The fork  23  is covered with a protective sheet  24  that is illustrated with broken lines in  FIG. 1 . 
         [0030]    In order to actuate the pivoting mechanism  2 , the piston  22  is displaced out of the cylinder  21  such that the fork  23  is moved toward the left. This in turn causes the lever  31  to be pivoted about an axis of rotation of the connecting bearing  32  and the cylinder  21  to be simultaneously turned about the mounting pin  25  together with the piston  22 . 
         [0031]    The following stipulation applies to the entire following description. If a figure contains reference symbols for reasons of graphical definition, but said reference symbols are not mentioned in the portion of the description directly pertaining thereto, the description refers to the corresponding explanation of the preceding figures. 
         [0032]    According to  FIG. 2 , an insert  4  in the form of a tubular section is arranged in the pipe section  11 , wherein the upper and the lower edge of said insert respectively feature a sealing channel  41 . A pivotable flap  5  with a disk  51  is arranged in the insert  4 , wherein a gap  53  is formed between the disk  51  and an inner edge of the insert  4 . During the operation, one respective seal is typically arranged in each of the sealing channels  41  such that the bulk material source and the bulk material destination can be tightly connected to the metering device. The mounting pin  25  extends through the receptacle  26  of the pivoting mechanism  2  and is screwed to the mounting part  13  of the housing  1  such that the receptacle  26  is rotatably supported on the mounting pin  25 . The fork  23  features two branches, between which the lever  31  is arranged, wherein the mounting pin  27  extends through both branches and the lever  31 . The protective sheet  24  is mounted on the fork  23  by means of the mounting pin  27  and another mounting pin  28 . 
         [0033]    The exploded view according to  FIG. 3  shows most clearly that the mounting pin  27  features an extension on one of its longitudinal ends, wherein said extension has a smaller diameter than that of the remaining mounting pin  27 . This extension is inserted into an opening of the fork  23 . On its other longitudinal end, the mounting pin  27  is screwed to the protective sheet  24  by means of a screw (not shown in  FIG. 3 ). On its longitudinal end that faces away from the mounting part  13  of the housing  1 , the mounting pin  25  features an annular groove that serves for securing the receptacle  26  of the pivoting mechanism  2  on the mounting pin  25 . The mounting pin  28  is also screwed to the protective sheet  24  by means of a screw (not shown in  FIG. 3 ) on one of its longitudinal ends. 
         [0034]    The upper flange  12  of the housing  1  transforms into the mounting part  13  toward the right, and the pipe section  11  of the housing  1  features a journal receptacle  111 , in which a journal of a flap can be arranged in such a way that it can be connected to the pivoting mechanism  2  through the journal receptacle  111 . 
         [0035]      FIG. 4  shows a cross section through the inventive metering device, in which certain components of  FIG. 5  and  FIG. 6 , respectively, are illustrated in the form of an exploded view in order to provide a better overview. The flap  5  features the disk  51  and two oppositely arranged journals  52  that are arranged on the disk  51  in the pivoting axis of the flap and respectively feature an interior that is open toward the outside. The journals  52  are rotatably supported between a lower first part  42  and an upper second part  43  of the insert  4 , wherein the journals are respectively surrounded by two annular vibration elements  67  that are offset relative to one another in the direction of the pivoting axis of the flap  5  and arranged between the journals  52  and the insert  4 . 
         [0036]    The metering device furthermore features vibration mechanisms including two eccentric rotors  61  that are realized in the form of unbalance rotors and respectively arranged in the interior of a journal  52 . The two rotors  61  are respectively connected in a rotationally rigid fashion to two adjacent ball bearings  62  in the direction of the pivoting axis of the flap  5  such that they are rotatable about the pivoting axis of the flap  5 . One respective ball bearing seal  63  is arranged between the four ball bearings  62  and the corresponding journal  52 . The respective interiors of the two journals  52  are sealed toward the outside with a counter bearing  64  that is respectively mounted in a rotationally rigid fashion with the aid of a screw  66 . Both screws  66  respectively feature a passage that extends in the direction of the pivoting axis of the flap  5  and an outwardly protruding compressed air connection  661 . Two annular counter bearing seals  65  are respectively arranged between the two counter bearings  64  and the corresponding journal  52 . The two counter bearings  64  are outwardly connected in a rotationally rigid fashion to one respective flanged shaft  35  that features a passage arranged in the direction of the pivoting axis of the flood  5 . 
         [0037]    The right flanged shaft  35  is outwardly connected in a rotationally rigid fashion to a hollow shaft  34  that features a passage arranged in the direction of the pivoting axis of the flap  5 , namely by means of an elastomer coupling  7 . The hollow shaft  34  is rotatably supported in the two-part connecting bearing  32  with the aid of two flanged bearing bushes  37 . It is also connected in a rotationally rigid fashion to the lever  31  by means of a feather key. The left flanged shaft  35  is outwardly connected to a sound absorber  8  that features an insert  81  of foamed material adjacent to the flanged shaft  35  and is closed by means of a cover  82 . 
         [0038]    During the operation of the metering device, the housing  1  is connected to a bulk material source and a bulk material destination in such a way, for example, that the lower first part  42  of the insert  4  is connected to the bulk material destination and the upper second part  43  of the insert  4  is connected to the bulk material source. One respective ring seal  45  is arranged in both sealing channels  41  of the first part  42  and the second part  43  in this case in order to ensure a tight connection between the metering device and the bulk material source and between the metering device and the bulk material destination. It is furthermore possible to act upon the vibration elements  67  from outside with a seal gas that is supplied via two seal gas channels  44  such that no bulk material or dust fractions thereof can laterally escape at the journals  52 . 
         [0039]    In order to open and close the metering device, the flap  5  is pivoted in the insert  4  by turning the lever  31  about the pivoting axis of the flap  5 . This simultaneously causes the hollow shaft  34  in the connecting bearing  32  to be turned, wherein the right journal  52  is also turned in the corresponding vibration elements  67  by means of the elastomer coupling  7  and the right flanged shaft  35 . During this process, the right journal  52  pivots the disk  51  such that the left journal  52  in the corresponding vibration elements  67  and the left flanged shaft  35  are also turned. 
         [0040]    In order to vibrate the flap  5  during the metering of bulk material, the two compressed air connections  661  of the screws  66  are connected to compressed air hoses that respectively extend through the hollow shaft  34 , the elastomer coupling  7  and the right flanged shaft  35 , as well as through the cover  82 , the insert  81  of foamed material and the left flanged shaft  35 . The vibrations are realized by respectively acting upon both rotors  61  with compressed air supplied through the corresponding compressed air hose such that they rotate about the pivoting axis of the flap  5  with the aid of ball bearings  62 . The unbalance of the eccentric rotors  61  causes the entire flap to vibrate. 
         [0041]      FIG. 5  shows most clearly that the four vibration elements  67  respectively feature an outer elastic ring  671  that faces the insert and an inner sliding ring  672  that faces the corresponding journal  52 . During the vibration of the flap  5 , the elastic ring  671  absorbs the vibrational movements of the flap  5  such that essentially no vibrational movements are transmitted from the flap  5  to the insert  4 . The sliding ring  672  features a flat inner surface, on which the corresponding journal  52  can be moved with little friction during a pivoting movement of the flap  5 . The elastomer coupling  7  also ensures that the vibration mechanism  6  is movably connected to the pivoting mechanism  2  such that the vibration is not stopped by the rigid pivoting mechanism  2 . Due to the fact that two vibration elements  67  that are offset relative to one another in the direction of the pivoting axis of the flap  5  are respectively arranged on both journals  52 , any tilting that would cause the disk  51  to be pressed into or against the insert  4  can essentially be prevented during the pivoting of the flap  5 . 
         [0042]    Although particular embodiments have been disclosed herein in detail, this has been done by way of example for purposes of illustration only, and is not intended to be limiting with respect to the scope of the appended claims, which follow. In particular, it is contemplated that various substitutions, alterations, and modifications may be made without departing from the spirit and scope of the invention as defined by the claims. Other aspects, advantages, and modifications are considered to be within the scope of the following claims. The claims presented are representative of the inventions disclosed herein. Other, unclaimed inventions are also contemplated. The applicant reserves the right to pursue such inventions in later claims.