The invention relates to an apparatus for metering a powdered or particulate material and comprising a material supply funnel, at least one material discharge opening, a slide in which at least one through-going metering opening is formed and which has a bottom surface closely abutting on a supporting surface and an upper surface closely adjacent to a rim part encircling the lower end opening of the supply funnel, and moving means adapted to reciprocate the slide between a filling position in which substantially all of the metering opening is aligned with the lower end opening of the supply funnel, and a discharging position in which the metering opening is aligned with the discharge opening formed in the supporting surface of the slide.

A ^* metering apparatus of this type adapted for metering of fodder is known from for example U.S. patent specification No. 1,10*3,009. This apparatus has a slide with a number of circular metering openings which are each in turn aligned with a fodder supply funnel and a fodder discharge opening, when the slide is reciprocated. Thus, when it is aligned with the fodder supply funnel, each metering opening together with the supporting surface of the slide forms a metering chamber which is open upwards and is automatically filled with the powdered or particulate fodder under the influence of gravity. hen the metering chamber thus filled is aligned with the discharge ope¬ ning formed in the supporting surface during the movement of the slide, the fodder will automatically fall down from the metering chamber or metering opening into the discharge opening. It is clear that by reciprocating the slide so that each of the metering openings of the slide is reciprocated between its filling and discharging positions, it is possible to have metered uniform amounts of powdered or particulate material supplied to each discharge opening.

However, this apparatus suffers from the disadvantage that during the reciprocating movement of the slide the upper edges of the metering opening will cooperate with the rim part encircling the lower end. opening of the supply funnel in a manner similar to the cutting edges of a pair of scissors. Thus, during the movement of the slide, some

of the grain- or pellet-shaped particles present in the metered fodder will be cut into two, and this means that the movement of the slide requires a relatively large and rather varying power supply. Further, foreign bodies like, for example, nails, screws, sticks or other metal or wooden objects which may be present in the fodder, may cause stops or faulty operation for the apparatus.

In the apparatus known from U.S. patent specification No. 4,604,970 (Danish patent application No. 1501/84), it has been attempted to avoid this disadvantage by giving the slide a relatively small thick- ness, and by arranging the slide at a distance from the lower end of the material supply funnel. Further, the slide is not provided with metering openings forming a metering chamber, but the slide has a pushing means with a concave pushing edge and a through- oing relief passage. In this known construction, the above cutting effect is avoided, and foreign bodies or larger particles of material may, if necessary, escape through the relief passage. In the latter known apparatus, the slide may therefore be reciprocated using a relatively low force. However, it has become clear that the amounts of fodder which may be metered by means of this apparatus vary to an extent which is unsatisfactory. For example, in metering feed pellets of nominal dimensions of 6 x 12 mm, the variation may be 10% or more.

U.S. patent specification No. 4,022,353 describes a metering appara¬ tus of the type mentioned above for metering shot and other particu¬ late materials. In this known apparatus at attempt has been made to solve the problem of trapping or cutting of particles in the metered material by making a part of the rim part encircling the lower end opening of the supply chute, or a rim part defining the metering opening at the upper surface of the slide, resiliently movable so that it may yield by overcoming an elastic force if any particles of material or foreign bodies are trapped during the metering. As a consequence of this spring-biassed rim part the known structure is relatively complex and vulnerable, and further, a rather large force is required to reciprocate the slide, because the driving force must be able to overcome the elastic force when particles of material are trapped.

The method according to the invention provides an apparatus by means of which it is possible to carry out a relatively accurate metering of powdered or particulate material without exposing particles of material or any foreign bodies in the metered material to a cutting effect and thus rendering the movement of the slide difficult.

The apparatus according to the invention is characterized in that the said openings are of such a shape and are so mutually arranged that part of the metering opening of the slide in the discharging position of the slide is still aligned with the lower end opening of the supply funnel. This means that there will be no cutting effect as in the former known apparatus between the upper edges of the metering opening in the slide and the rim part encircling the lower end ope¬ ning of the supply funnel, but as the upper surface of the slide, contrary to the pushing means of the slide according to the above U.S. patent specification No. 4,604,970, is closely adjacent to this rim part, the part of the metering opening which is each time aligned with the upper end opening of the discharge chute, will form a me¬ tering chamber of a.well defined volume.

The metering opening may have any desired shape, and it may thus be circular as in the above known apparatus, or square. However, in the preferred embodiment, the metering opening has a shape which is elongated in the longitudinal direction of the slide, and it may, for example be elliptical or rectangular. It is, however, preferred to form the metering opening in a width which decreases from the end part which is farthest away from the supply funnel in the discharging position of the slide, in a direction towards the opposite end of the metering opening. The end of the metering opening which is continual¬ ly, and also in the discharging position, aligned with the material supply funnel, may then have a fairly small width. The metering opening may thus, for example be drop-shaped.

For each supply funnel, the apparatus according to the invention may have two discharge openings which are arranged at opposite sides of the lower end opening of the common supply funnel, and two metering openings for respective discharge openings may then be arranged in the slide, and the metering openings may be arranged so that one of

the metering openings is in its discharging position when the other is in its filling position, and vice versa. The apparatus of the invention may, for example, be used in a feeding apparatus of the type described in the above U.S. patent specification no. 4,604,970 (Danish patent application No. 1501/84), and the embodiment descri¬ bed, having one supply funnel and two discharge openings, may then constitute a unit of which any desired number may be built together so that a feeding apparatus with the desired number of discharge openings and a corresponding number of feeding places is obtained.

When the metering apparatus according to the invention is used for metering of grain-shaped or particulate fodder, for example feed pellets, the metering opening preferably has a height of 10-20 mm. If the height becomes smaller, it will be difficult for the large fodder particles to be received by the metering chamber formed by the me- tering opening, and if the height becomes substantially larger, the metering accuracy will deteriorate, because each time the fodder material is discharged from the metering chamber, a varying angle of slide could be formed for the material remaining in the part of the metering opening which is not brought into alignment with the dis- charge opening.

Generally, the metering opening and thus the height of the slide should be larger than the nominal maximum dimension for the particles metered. If, for example, feed pellets are involved whose nominal dimensions are 6 x 12 mm, the metering opening is preferably given a height of about 16 mm, as some of the pellets will have dimensions exceeding the nominal values.

The discharge opening may form the upper end of a discharge funnel which may, for example, be formed as a tube or a chute, but the metered quantities of material may also fall freely directly from the opening formed in the supporting surface of the slide down to the place of destination, which may, for example, be a feeding place.

Although the apparatus according to the invention has been described above with special reference to metering of fodder materials in feeding apparatuses, it is clear that the apparatus according to the

invention may be used for metering of any other type of powdered or particulate material, for example for metering of uniform amounts of material to be packed. In the latter case the metered material from the discharge opening may be supplied to containers or other packa- gings which are successively guided past the discharge end of a discharge chute.

The invention will now be explained with reference to the drawing, in which

Fig. 1 is a perspective view, partly cut away, of a feeding apparatus containing a number of coupled metering apparatuses according to the invention,

Fig. 2 is a perspective view, partly cut away, of one end of the feeding apparatus shown in Fig. 1, in a larger scale, Fig. 3 is a perspective view of an embodiment of the metering appara- tus according to the invention in its separate parts, and

Figs. 4 and 5 are perspective, partially sectional views of the metering apparatus shown in Fig. 3 with the slide in its two extreme positions.

Fig. 1 shows an automatic feeding apparatus of the type known from the above US patent specification No. 4,604,970 (Danish patent appli¬ cation No. 1501/84). This feeding apparatus is of such a shape that it may serve as a partition between two enclosures or pigpens, and on both sides of the feeding apparatus a number of mutually adjacent separate trough sections or feeding places 10 are arranged. The fodder for these feeding places is supplied through a number of fodder supply ducts 11 which extend upwards from the apparatus to a suitable fodder supply conveyor (not shown) . Inside a space defined by the end walls 12, sloping side walls 13 and a top wall 14 of the feeding apparatus, a number of coupled metering apparatuses 15 have been arranged which, in a manner to be described below, serve to dispense fodder supplied through the supply ducts 11, to the indivi¬ dual feeding places 10. The fodder is in the form of particulate dry- fodder, for example feed pellets, and therefore, the feeding places 10 should normally also be supplied with liquid. This liquid, which may be water, milk, whey, or another nutritious liquid, is supplied

through liquid supply tubes 16 from which, by selective control of valves 17, liquid may be dispensed to the individual feeding places through liquid dispensing tubes 18, of which one is provided for each feeding place.

Each metering apparatus 15 has a frame or housing 19 with a bottom wall 20, opposite side walls 21 and flange-shaped top walls 22 ex¬ tending from the side walls. The flange-shaped top walls 22 are interconnected by means of a pipe stub 23 serving to telescopically receive one of the fodder supply ducts 11. On the lower surface of the bottom wall 20 reinforcing ribs 24 have been formed, and on the upper surface of the top walls 22 transverse and oblique reinforcing ribs 25 and 26, respectively, have been formed. Furthermore, at its corners the housing or frame 19, which may suitably be molded from plastic or metal, for example from an aluminum alloy, has screw receiving bushings 27 through which screws or bolts serving to fasten the metering apparatus 15 in the feeding apparatus may be passed.

The inner surfaces of the bottom wall 20, the side walls 21 and the top wall 22 define a channel with a substantially rectangular cross- section and serve as a guide for a metering slide 28 with a centre part 29 having a cross-section corresponding to the cross-section of the channel defined by the housing or frame 19. At its opposite end the slide 28 further has triangular connecting parts 30 with holes 31 for receiving screws, rivets or similar connecting parts. In the centre part 29 of the slide, two identical drop-shaped metering openings 32 have been formed which are arranged symmetrically in relation to the centre of the centre part 29, and whose narrowest ends head towards each other. At each of the opposite ends of the bottom wall 20 of the housing 19, a discharge opening 33 has been formed. The inner limits of these discharge openings 33 are located a distance beyond the pipe stub 23 and preferably symmetrically in relation to the longitudinal axis of the pipe stub.

In the feeding apparatus shown in Figs. 1 and 2, several metering apparatuses 15 as the one described above and as shown in Figs. 3-5 are arranged along each other so that the channels defined in the housings 19 are aligned, and the metering slides 28 in adjacent

metering apparatuses 15 are interconnected by means of rod-shaped connecting pieces 34, the ends of which are connected with the adja¬ cent triangular connecting parts 30 "of the slide 28 by means of bolts, rivets or similar fastening means 35 which are passed through the holes 31 in the connecting parts 30, vide Fig. 2. The metering slides 28 so interconnected may all be reciprocated by means of an electric motor 36 via a crank mechanism 37, vide Fig. 2,

The slide 28 in each of the apparatuses may be moved between two extreme positions shown in Figs. 4 and 5, respectively. In the ex- treme position shown in Fig. 4, all of one of the metering openings 32 in the slide 28 is aligned with the pipe stub 23 and the fodder supply duct 11 received therein, which is filled with free-flowing, particulate fodder 38, for example feed pellets, while the wide part of the other metering opening 32 is aligned with one of the discharge openings 33, and its narrow end is aligned with the pipe stub 23. In this position, said one metering opening will be closed downwardly by means of the bottom wall 20 and will thus form an upwardly open metering chamber which is filled with fodder. When the slide 28 is , then displaced to the position shown in Fig. 5, the metering opening 32 which has just been filled and serves as a metering chamber, will be moved with its wide part over the associated discharge opening 33, whereby the fodder in the part of the metering opening 32 aligned with the discharge opening will fall down through the discharge opening. However, at its narrow end, the metering opening 32 will remain in contact with the inside of the pipe stub 23 and the fodder supply duct 11, whereby fodder particles are prevented from being exposed to a cutting effect between the lower, inner rim 39 of the pipe stub 23 and the upper, back (seen in the direction of movement) edge 40 of the metering opening 32, even though the upper surface of the slide 28 is closely adjacent to the lower end surface of the pipe stub 23. It will be understood that a reciprocating movement of the slide 28 between its extreme positions will involve discharge of a metered amount of fodder from each of the discharge openings 33. The two discharge openings 33 in each of the metering apparatuses compri- sed in the feeding apparatus shown in Figs. 1 and 2 are connected with respective feeding places 10 arranged on opposite sides of the feeding apparatus. Each time the electric motor 36 displaces the

coupled metering slides 28 from one extreme position to the other, equally large fodder portions will thus simultaneously be discharged into all trough sections or feeding places 10 on one side of the apparatus, and at the subsequent displacing movement of the coupled slides equally large fodder amounts will be discharged into all trough sections or at all feeding places 10 on the other side of the apparatus. The electric motor 36 is preferably a step motor driven in such a manner that a suitable pause is made at the extreme positions for each displacing movement of the slides 28. The valves 17 are preferably controlled so that simultaneously with the supply of a portion of dry fodder to the feeding places 10, a suitable amount of liquid is supplied through the liquid dispensing tubes 18.

The feeding apparatus shown in Figs. 1 and 2 is especially adapted for feeding hogs or swine, but may also be used for feeding other loose animals in the same enclosure. The metered fodder portions supplied to the individual feeding place 10 are preferably of a size corresponding to a single or a few mouthfuls, and the movement of the slides 28 is controlled so that the interval between consecutive fodder supplies to the individual feeding place 10 is so long that the animals at the individual feeding place have time enough to eat a supplied fodder portion before the next one is supplied. The metering apparatus according to the invention is thus suitable for use in carrying out the method described in Danish patent application No. 2439/80 (published specification no. 145444B) . When carrying out this method it is of substantial importance that the fodder portions may be metered out with great accuracy. It has been shown that by using the metering apparatus according to the invention the metering may be carried out with such an accuracy that the maximum deviations from the nominal metering amount only come to about 2%.