US20080041883A1

US20080041883A1 - Metering device

Info

Publication number: US20080041883A1
Application number: US11/893,084
Authority: US
Inventors: Fritz Schaub
Original assignee: Novindustra AG
Current assignee: Novindustra AG
Priority date: 2006-08-15
Filing date: 2007-08-13
Publication date: 2008-02-21
Also published as: DE502007000661D1; ATE430105T1; EP1889797B1; EP1889797A1

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

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

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.
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.
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.
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

Embodiments of the present invention relate to a metering device for metering bulk materials without contaminating them.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
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.
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.
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

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:

FIG. 1 is a side view of a metering device, in accordance with an embodiment of the present invention.

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.

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.

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.

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.

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

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

1. A metering device for metering bulk materials comprising:

a flap, wherein the flap is allowed vibrations; and

an insert,

wherein the flap is allowed to pivot within the insert, and

wherein the flap is supported in the insert which remains dimensionally stable during the vibrations.

2. The metering device according to claim 1, wherein the insert is made of a relatively strong and relatively hard material.

3. The metering device according to claim 1, further comprising:

at least one elastically deformable vibration element,

wherein the flap features at least one journal that is supported in the insert; and

a disk,

wherein the at least one elastically deformable vibration element is arranged around the at least one journal between the at least one journal and the insert.

4. The metering device according to claim 3, wherein the at least one elastically deformable vibration element features an anti-friction layer on its inner side.

5. The metering device according to claim 4, wherein a seal gas acts upon the at least one elastically deformable vibration element.

6. The metering device according to claim 3, featuring a gap between the insert and the disk when the flap is in a closed position in the insert.

7. The metering device according to claim 3, wherein the insert comprises:

a first part, a second part and a connecting means, wherein the first part and the second part are separably connected to one another via the connecting means, and wherein the at least one journal is supported between the first part and the second part.

8. The metering device according to claim 7, further comprising:

a pivoting mechanism, wherein an elastomer coupling is arranged between the at least one journal and the pivoting mechanism.

9. The metering device according to claim 8, in which the pivoting mechanism features a pneumatic linear drive for pivoting the flap.

10. The metering device according to claim 8, further comprising:

a vibration mechanism with an eccentric rotor and rotating means,

wherein the eccentric rotor is rotatably arranged on a pivoting axis of the flap, and wherein the rotor vibrates the flap when the rotating means turn the rotor.

11. A metering device for metering bulk materials which comprises a flap and an insert, wherein the flap can be pivoted in the insert, wherein the flap can be vibrated, and wherein the flap is supported in the insert in such a way that the insert essentially is dimensionally stable while the flap vibrates.

12. The metering device according to claim 11, wherein the insert is made of a relatively strong and relatively hard material.

13. The metering device according to claim 11 which comprises at least one elastically deformable vibration element and in which the flap features at least one journal that is supported in the insert and a disk, wherein the vibration element is arranged around the journal between the journal and the insert.

14. The metering device according to claim 13, wherein the elastically deformable vibration element features an anti-friction layer on its inner side.

15. The metering device according to claim 13, featuring means for acting upon the vibration elements with a seal gas.

16. The metering device according to claim 11, featuring a gap between the insert and the disk when the flap is in a closed position in the insert.

17. The metering device according to claim 11, in which the insert features a first part, a second part and connecting means, wherein the first part and the second part are separably connected to one another with the aid of the connecting means, and wherein the journal is supported between the first part and the second part.

18. The metering device according to claim 11, featuring a pivoting mechanism, wherein an elastomer coupling is arranged between the journal and the pivoting mechanism.

19. The metering device according to claim 18, in which the pivoting mechanism features a pneumatic linear drive for pivoting the flap.

20. The metering device according to claim 11, featuring a vibration mechanism with an eccentric rotor and rotating means, wherein the rotor is rotatably arranged on a pivoting axis of the flap, and wherein the rotor vibrates the flap when the rotating means turn the rotor.