This invention relates to a dosing device for dosing powder.

By dosing device, here any dosing device has to be understood which allows to adjust a flow, in this case, a flow of powder, from large to small, and preferably also to stop it completely.

Such dosing device makes it possible to drain a precisely determined quantity from a receptacle or to bring it into a receptacle, mostly in combination with a weighing device or another measuring device.

Such dosing devices are provided, fixed or removable, at the exit beneath a silo, a barrel or another receptacle or a funnel or are installed in a conduit.

With liquids, dosing may take place by means of the valve which is present for closing off. The valve is opened completely until the desired quantity is reached, after which the valve is almost closed and still lets through a very small flow which, by closing the valve, immediately is brought to zero when the desired quantity exactly has been reached.

This manner of working, however, is not possible with powders. The viscosity of powders is much lower than that of a liquid and moreover strongly differs according to the kind of powder.

Even with a completely open valve, it may happen that the powder is stuck, but surely with a small opening of the valve, the powder will not flow therethrough by the

effect of gravity only.

Therefore, known dosing devices comprise a driven dosing screw or worm for pressing the powder outward and a valve which can be brought into completely open or completely closed condition for entirely closing off the exit after dosing.

The more precision is required for dosing, the smaller the diameter of the screw and, thus, the smaller the maximum flow rate which can be delivered by the screw.

In any case, the flow rate is limited by the screw, which means that, in consideration of the fact that all of the powder has to be moved by the screw, it will take a relatively long time until the desired quantity of powder has been delivered if this latter is relatively large.

Moreover, the necessity of a driven screw as well as of a closing valve renders the dosing device relatively bulky and expensive.

The invention has as an aim to remedy these disadvantages and to provide a dosing device which does not only allow a precise dosing, but with which the desired quantity can be obtained in a fast manner and which, moreover, can be realized relatively inexpensive and compact.

According to the invention, this aim is achieved in that the dosing device comprises a butterfly valve beared in a valve housing and means for rotating this butterfly valve in the valve housing, whereby at least one vibrating mechanism is provided on the butterfly valve.

The butterfly valve can be turned completely open until the desired quantity is almost reached, as a result of

which the major part of the powder can flow through the device at a large flow rate. If the flow is not maximum, the butterfly valve can be vibrated.

Thereafter, the valve is almost closed. By vibrating the butterfly valve, the powder on the butterfly valve behaves like a liquid, and the powder even will flow through a small valve opening.

The use of a vibrating mechanism in order to enhance the flow of a powder, is known in itself, but the vibrating mechanism is mounted on the receptacle to be emptied or on a table upon which the latter is mounted, and not on the valve at the exit of the receptacle, which valve in fact is a closing valve and can not be used for dosing.

Practically, the vibrating mechanism according to the invention has a high frequency, this is a frequency higher than 50 Hz and preferably between 280 and 390 Hz.

The vibrating mechanism can be incorporated in the axle with which the butterfly valve is beared in the valve housing.

The valve housing preferably comprises an elastic ring, for example, a ring made of silicone rubber.

This ring can provide entirely or partially for sealing when the device is mounted at the outlet opening of a receptacle.

In view of this mounting, the dosing device may comprise a conical ring which cooperates with a conically narrowed extremity of the valve housing, whereas the whole can be surrounded by a pot which, possibly detachable, can be attached to the receptacle or silo or similar.

The turning of the butterfly valve can be performed automatically or manually. In this latter case, the dosing device comprises a, preferably detachable, handle which is connected to the axle of the butterfly valve and protrudes out of the valve housing.

With the intention of better showing the characteristics of the intention, hereafter, as an example without any limitative character, a preferred form of embodiment of a dosing device according to the invention is described, with reference to the accompanying drawings, wherein : figure 1 represents a perspective view of a dosing device according to the invention, with the parts taken apart ; figure 2 represents a cross-section according to line II-II in figure 1 ; figure 3 represents a cross-section according to line III-III in figure 2 ; figure 4 represents a cross-section of a barrel on which a dosing device according to the invention is mounted ; figure 5, at a larger scale, represents the part indicated by F5 in figure 4.

The dosing device represented in figures 1 and 2 substantially consists of a ring-shaped valve housing 1 in which a round butterfly valve 2 is beared on which at least one, and in the represented example, two, vibrating mechanisms 3 are provided, and means for turning the butterfly valve 2 in the valve housing 1 which, in the represented example, are manual means, formed by a detachable handle 4.

The ring-shaped valve housing 1 is elastically deformable in order to allow the mounting and dismounting of the

butterfly valve 2 without using a tool. To this aim, this valve housing 1 is manufactured of synthetic material, in particular silicone rubber.

Said ring-shaped valve housing 1 is provided with two diametrically opposed round openings 5 and, at one extremity, is provided with a conical part 6 at the inside.

The butterfly valve 2 consists of a round disc 7 with two diametrically opposed recesses and an axle consisting of two hollow axle ends 8 which are attached to the round disc 7 at the location of a'recess.

In each hollow axle end 8, a vibrating mechanism 3 is provided which consists of an excenter element 9 which is attached to an axle 10 and which is driven pneumatically at a frequency which is larger than 50 Hz and preferably between 280 Hz and 390 Hz.

As represented in figure 3, in the represented example this excenter element 9 is formed by a round disc which, around its center, is provided with openings of which two adjacent ones are filled with heavy-weight metal.

The excenter element 9 is installed axially in the axle end 8 in a round cavity 11 which surrounds the excenter element 9 excentrically and which is closed off at the exterior side by a plug 12.

At the exterior side, into said plug 12 consisting of synthetic material, a connection nipple 13 is screwed to which a compressed air conduit 14 is attached which is connected to a source of compressed air which can be switched on and off, more particularly, for example, a source with a pneumatic valve 15 which itself is

connected to a compressed air reservoir.

Said connection nipple 13 is connected to the cavity 11 by means of a channel 16 and a peripheral groove 17 in the plug 12 and a channel 18 in the axle end 8. The channel 18 tangentially gives out onto the corrugated periphery of the excenter element 9, at the location where this latter is situated nearest to the interior wall of the cavity 11.

Through a channel 19 connected to the cavity 11 at the location where the excenter element 9 is situated at its largest distance from the interior wall of the cavity 11, or somewhat beyond this location seen in the rotational direction of the excenter element 9, which channel passes through the material of the axle end 8 up to the exterior side thereof, the used compressed air can escape.

By compressed air which is blown onto the excenter element 9 through channel 18, said excenter element 9 is put into rotation. The flow rate is adapted such that the rotational speed causes the aforementioned vibration frequency.

The two vibrating mechanisms 3 simultaneously are fed with compressed air, and the two vibrating mechanisms rather fast will work in synchronisation in order to vibrate the butterfly valve 2.

At the exterior side, each axle end 8 comprises an end piece 20 made of synthetic material which covers the plug 12 and is screwed to the remainder of the axle end 8 and is provided with a square opening 21 in its center into which the square end of the handle 4 is fitting.

This end is hollow and surrounds the connection nipple

13. The compressed air conduit 14 which is connected to this latter, extends through a hollow pipe-shaped portion of the removable handle 4.

The two axle ends 8 are surrounded by sleeves 22 which are provided in the two openings 5.

First, one axle end 8 is provided in the one opening 5, after which, by elastic deformation of the valve housing 1, the other axle end 8 is pushed into the other opening 5 and subsequently in each opening 5 a sleeve 22 is provided around the axle end 8 and only thereafter the compressed air conduits 14 and the handle 4 are provided.

For attaching the valve housing 1 with the butterfly valve 2 on the exit of a receptacle, the dosing device comprises an outer housing 23 in the shape of a pot with at one extremity an outwardly-directed collar 24 and at its other extremity an open portion with a smaller diameter, such that an inner collar 25 is formed.

The outer housing 23 is provided with two diametrically opposed openings 26 and, in the proximity of the collar 24, has a small opening 27.

The valve housing 1 with therein the butterfly valve 2 fits precisely into the outer housing 23, with its not- narrowed extremity on the inner collar 25. In this outer housing 23, also a conical ring 28 is fitting which cooperates with the conical portion 6 of the valve housing 1.

This conical ring 28 has an outwardly-directed collar 29 at its widest extremity, which collar, when the ring 28 rests against the conical portion 6, is situated opposite to the collar 24 of the outer housing 23.

In figures 4 and 5, the dosing device is represented in mounted condition, installed at a receptacle 30.

As a standard, such receptacles are provided with a protruding rim 31 at their filling opening, at which rim during transport a lid with a clamping ring can be fixed.

Such receptacles 30 are also used for transporting poisonous and/or environmentally unfriendly powders, and in such cases they mostly are lined by one or two liners of plastic foil. In figure 2, such receptacle 30 with two liners 32 and 33 is represented.

The dosing device described in the aforegoing is constructed such that these two liners 32 and 33 with their open extremity also are fixed in the dosing device when this latter is mounted.

The attachment of the dosing device on the receptacle 30 takes place with an upright-standing receptacle 30 and as follows : The lid is removed from the receptacle 30, the exterior liner 32 is folded outward over the rim 31 of the receptacle 30, and the conical ring 28 is placed with its collar 29 onto this rim, with the liner 32 in between.

Around the ring 28 and against its collar 29, a rubber sealing ring 34 is provided.

The inner liner 33 is opened and folded outward over the narrow extremity of the conical ring 28.

The outer housing 23, in which the butterfly valve 2 has been provided in the manner described in the aforegoing, with the two vibrating mechanisms 3 onto which compressed

air conduits 14 have been connected and to which the handle 4 has been attached, is placed, upside down in respect to the position represented in the figures, over the conical ring 28, with the elastic sealing ring 34 between the opposed collars 29 and 24 of the ring 28 and the outer housing 23, respectively.

Subsequently, the collar 24 of the outer housing 23 is connected to the rim 31 of the receptacle 30 by means of a clamping ring 35.

With the butterfly valve 2 in closed position, the receptacle 30 is brought upside down and on top of the receptacle which has to be filled with a dose which has to be precisely determined. For safety's sake, a cap can be temporarily provided on the narrow extremity of the outer housing 23 or of an extension piece connected thereto.

The receptacle 30 and the dosing device provided thereon, however, without cap, are represented in this position in figures 4 and 5.

The tilting can be performed by means of a so-called manipulator, this is a device for lifting and tilting the receptacle 30, in which the outer housing 23, for example, is attached by clamping. In a variant, this outer housing 23 may form a part of the manipulator.

Before filling, the possible cap is removed, and by means of handle 4, the butterfly valve 2 is turned into open position.

When from weighing this receptacle, it is indicated that the desired weight of powder in this latter is almost reached, then the butterfly valve 2 is partially closed

and so the more the smaller the weight quantity which still has to be dosed.

In order to obtain a continuous flow of the powder even with a partially and even almost completely closed butterfly valve 2, also with a powder flowing only with difficulty, the butterfly valve 2 is vibrated by supplying compressed air through the compressed air conduits 14 to the vibrating mechanisms 2.

As a result of the relatively high vibration frequency, the powder which is on the butterfly valve 2 will behave like a liquid and even flow through a small gap.

In order to prevent that, when the receptacle 30 is almost empty, the inner liner 33 drops downward onto the butterfly valve 2, a vacuum can be created between the liners 32 and 33.

To this aim, a vacuum conduit 36 is connected to the opening 27 in the outer housing 23. Through openings cut into the outer liner 32 and an opening 37 in the conical ring 28, air is suctioned from the space in between the two liners 32 and 33.

When the receptacle 30 is empty or when the dosing is finished, the butterfly valve 2 is brought into closed position, and the receptacle 30 is turned upright again and put down.

If the receptacle 30 is empty, then the clamping ring 35 is loosened and the dosing device, except the conical ring 28, is taken from the receptacle 30, after which the inner liner 33 is closed and removed, after which also the conical ring 28 is taken off and the outer liner 32 is removed.

Thereafter, the dosing device is provided in the above- described manner on a new receptacle 30.

The last receptacle 30 whereby dosing has taken place exactly up to the desired quantity, mostly will not be completely empty. In this case, the dosing device is left upon the receptacle 30. Only the handle 4 is removed, and the compressed air conduits 14 and the vacuum conduit 36 are uncoupled before the dosing device is removed from the manipulator.

Then, the receptacle 30 is stored away, whereas it is closed off by the butterfly valve 2 and possibly an additional cap which is placed upon the outer housing 23.

The dosing device described in the aforegoing does not only allow a very precise dosing of powders, but moreover can be connected to, and uncoupled from, the usual receptacles, possibly with one or two liners provided therein, in a simple manner.

It is clear that the dosing device not necessarily has to comprise two vibrating mechanisms 3. One may be sufficient.

Moreover, it may comprise another vibrating mechanism than described. So, the excenter element 9 also can be driven by an electric motor.

Besides, the vibrating mechanism 3 does not necessarily have to be situated in an axle end, inasmuch as it directly sets the butterfly valve vibrating. Thus, the mechanism may be provided on the disc 7.

The butterfly valve 2 does not necessarily has to be turned manually by means of a handle 4. The means for

turning the butterfly valve 4 also may comprise a motor.

The invention is in no way limited to the forms of embodiment described heretofore or represented in the figures, on the contrary can such dosing device be realized in different variants while still remaining within the scope of the invention.