METHOD AND PLANT FOR MEASURING AND PORTIONING OF FODDER

Abstract: In a method of measuring and portioning of fodder a fodder portioner (1) provided with a dispensing device (5, 7) is utilized for dispensing an optional quantity of fodder. According to the invention a) the dispensing device (5, 7) is activated, b) the weight of the dispensed fodder from the fodder portioner is sensed, c) the value of a volume related variable for dispensing the fodder is registered when a given weight of the dispensed fodder from the fodder portioner is sensed, and d) on the basis of said registered value, the dispensing device is kept activated until the desired weight of fodder has been dispensed from the fodder portioner. Hereby, the fodder portioner can be provided with for instance an inexpensive loading cell for sensing only a maximum and a minimum value.

Description: Method and plant for measuring and portioning of fodder The present invention relates to a method of measuring and portioning of fodder by means of a fodder portioner provided with a dispensing device for dispensing an optional quantity of fodder. The invention also relates to a plant for such measuring and portioning of fodder. When portioning fodder in an animal stable by means of a plant of this kind comprising one or more fodder portioners placed at the feeding places of the stable, it is desirable that the dosing of the fodder takes place in such a way that the intended weight of fodder is dispensed with an acceptable accuracy from each fodder portioner at each feeding occasion. However, this desire about dosing accuracy must not mean that such complicated and expensive fodder portioners need to be used that investment in such a plant would not be profitable. Therefore, known fodder portioners are usually adapted to dose the volume of the fodder, which is intended to correspond to the desired weight of fodder. Such volume dosing fodder portioners are of a relatively simple construction and are therefore inexpensive. A known such an inexpensive fodder portioner of the volume dosing kind comprises a container with a replenishment tube lowered therein. By manual adjustment of the height of the tube in the container, refillable volume in the container can easily be adjusted, the refillable volume corresponding to the desired fodder dose. Thus, from the container the entire content of fodder is dispensed at each feeding occasion by means of a dispensing device of some kind. Another known fodder portioner of the volume dosing kind com¬ prises a feed screw, which by means of fixed time control is adapted to dispense the intended fodder dose. See for instance US 4.491.086. However, it has proved that the weight per volume unit of fodder can vary _ 20 %. Therefore, the known volume dosing fodder portioners should be regularly corrected, so that the dispensed doses will have acceptable accuracy. However, such corrections must be carried out manually for each fodder portioner, which is expensive. Satisfactory accuracy of dispensed fodder doses may be achieved if each fodder portioner of the kind here present is provided with some kind of weighing means, by means of which the fodder is weighed into doses of desired weight. However, a plant com¬ prising such fodder portioners will be too expensive if the number of fodder portioners is large. In addition, when dosing small fodder portions high demands on the weighing means are called for, if high dosing accuracy is to be achieved, which raises the price of the plant even further. EP 0272054 discloses a computer controlled feeding plant, com¬ prising a plurality of fodder portioners of the volume dosing kind and having one single weighing device for weighing the total quantity of fodder to be distributed to the fodder portioners. The computer is adapted to calculate the average weight of fodder per dose on the basis of the measured total weight of fodder. However, this known feeding plant has a too poor dosing accuracy and will also be too expensive if only one fodder portioner is utilized. The object of the present invention is to provide a new method of measuring and portioning of fodder, which gives a high dosing accuracy by means of simple and inexpensive means. A further object is to provide a new plant for measuring and portioning of fodder, which to comparatively low price allows a higher dosing accuracy than plants comprising the above described known fodder portioners of the volume dosing kind. These objects are obtained by means of a method of the kind initially stated, which mainly is characterized in that the dispensing device is activated; that the weight of the fodder dispensed from the fodder portioner is sensed; that the value of a volume related variable for dispensing the fodder is regis¬ tered when a given weight of the dispensed fodder from the fodder portioner is sensed; and that on the basis of said registered value the dispensing device is kept activated until the desired weight of fodder has been dispensed from the fodder portioner. Hereby, the advantage is achieved that a weighing means of a simple and inexpensive kind can be utilized, for instance a loading cell. Thus, this needs only be adapted to indicate a first high value and a second low value on the weight of a fodder portioner with fodder content, the difference between said first and second values constituting the value on said given weight. In addition, the advantage is achieved that if at least one further fodder portioner is utilized only one of the portioners needs to be provided with a weighing means, while all of the other fodder portioners can be constituted by conventional inexpensive fodder portioners of the volume dosing kind. Preferably, the volume related variable is constituted by the time for dispensing the fodder. In case the dispensing device comprises a rotatable feed screw the volume related variable can advantageously be constituted by the number of revolutions of the feed screw for dispensing the fodder. The invention also relates to a new plant for measuring and portioning of fodder, comprising a fodder portioner provided with a dispensing device for dispensing an optional quantity of fodder. The new plant is mainly characterized in that the fodder portioner is provided with a weighing means for sensing the weight of dispensed fodder; that the dispensing device of the fodder portioner is connected to a control unit, which during operation of the plant is adapted to sense a volume related variable for dispensing the fodder; that the control unit is adapted to register the value of the volume related variable in response to the weighing means, when a given weight of dispensed fodder is sensed by the latter; and that on the basis of said registered value the control unit is adapted to control the dispensing device, such that the desired weight of fodder is dispensed from the fodder portioner. With advantage, the new plant comprises at least one further fodder portioner with a further dispensing device, the control unit being connected to said further dispensing device and adapted to control said further dispensing device on the basis of said registered value, such that the desired weight of fodder is dispensed from said further fodder portioner. Hereby, there is no need for providing each of said at least one further fodder portioner with a weighing device. Preferably, the control unit is adapted to sense the time for dispensing the fodder. Suitably, each dispensing device comprises a rotatable feed screw, the control unit advantageously being adapted to sense the number of revolutions which each feed screw turns during the dispensing of fodder. The invention will be explained more closely in the following with reference to the accompanying drawing, in which an embodi¬ ment of the plant according to the invention is schematically shown. The plant shown in the drawing comprises a plurality of fodder portioners 1, 2 (for simplification of the drawing there is shown only two fodder portioners), which have the form of verti¬ cally directed tubes 3, 4. At the lower ends of the tubes 3, 4 there are identical feed screws 5, 6 turnably arranged for dis¬ charging fodder from the tubes. The feed screws 5, 6 are driv- able by means of drive motors 7, 8, which during operation run on the same and constant rotation speed. A container 9 for fodder is via a distribution conduit 10 connected to the fodder portioners 1, 2. In the distribution conduit 10 there is a feed screw 11 for transportation of fodder from the container 9 to the respective fodder portioners 1, 2. A drive motor 12 is coupled to the feed screw 11 for driving the latter. The fodder portioner 1 is suspended from the weighing means 13 in the form of a loading cell. (Alternatively the weighing means 13 may be constituted by a strain gauge or a balance arm). A vertical replenishment tube 14 extends from the distribution conduit 10 a distance down into the tube 3 without being in rigid connection with the tube 3. In the replenishment tube 14 there is a valve 15, which is adjustable between an open and a closed position. (The valve 15 is only needed in certain cases dependent on how the plant is operated, which is clear from the description below of the function of the plant) . A control unit 16 in the shape of a micro processor is via conduits 17, 18, 19, 20 and 21 coupled to the drive motor 8, the drive motor 12, the valve 15, the weighing means 13 and the drive motor 7. By dashed lines in the drawing there is indicated an alternative embodiment of the plant comprising impulse generators 22, 23, which are arranged to indicate the number of revolutions the feed screws 5, 6 rotate. The impulse generators 22, 23 are coupled to the control unit 16 by means of conduits 24, 25. The plant is operated in the following way: First all of the fodder portioners 1, 2 are filled with fodder by the control unit 16 activating the drive motor 12 and keeping open the valve 15 of the replenishment tube 14. In this described case the valve 15 may possibly be abolished. Hereby the feed screw 11 feeds fodder from the container 9 to the fodder portioners 1, 2 via the distribution conduit 10. The control unit 16 also acti¬ vates the drive motors 7 and 8 for a short while so that the feed screws 5 and 6 are filled with fodder. Then the control unit 16 closes the valve 15 and stops the drive motor 12. Now the tube 3 of the fodder portioner 1 is filled with fodder up to the opening of the replenishment tube 14 in the tube 3. Then the control unit 16 activates the drive motor 7, so that the feed screw 5 starts discharging fodder from the fodder portioner 1. When the total weight of the fodder portioner 1 has sunk to a predetermined first value this is indicated by the weighing means 13, the control unit 16 starts registrating the running time of the drive motor 7. (Alternatively the control unit 16 may close the valve 15 during the filling of a portioner 1 when the weighing means 13 indicates said predetermined first value). When the total weight of the fodder portioner 1 has sunk further to a predetermined second value this is indicated by the weighing means 13, the control unit 16 registers the value of the running time of the drive motor 7 between said indications of the weighing means 13. Said registered running time value thus constitutes a measure of the time for dispensing a pre¬ determined weight of fodder. Since the rotation speed of the drive motor 7 is constant the dispensing time depends on the volume of the dispensed fodder. (Alternatively the control unit 16 may register the value of the total weight of the fodder portioner 1 measured by the weighing means 13 when the fodder portioner 1 is completely filled before the drive motor 7 is activated. On the basis of this registered weight value and indications from the weighing means 13 the control unit 16 then may register the value of the running time of the drive motor 7 when a predetermined weight of fodder has been dispensed) . Then the control unit 16 calculates a value of the dispensing flow of fodder from the fodder portioner 1 by weight per time unit on the basis of the predetermined weight of dispensed fodder and the registered value of the running time of the drive motor 7 for dispensing the fodder. On the basis of the calcula- ted value of the dispensing flow of fodder the control unit 16 then controls the drive motors of all of the fodder portioners, so that the desired fodder portion is dispensed from each of the fodder portioners. Alternatively the control unit 16 may register the number of revolutions which the feed screw 5 rotates during the dispensing of fodder if any of the drive motors of the portioners does not have the same rotation speed. In this case the number of revolu¬ tions of the feed screw may be indicated by means of the impulse generators indicated in the drawing. Hereby the control unit 16 calculates the value of the discharge weight of fodder per revo¬ lution of the feed screw. On the basis of this calculated value the control unit 16 then controls the drive motors of all of the fodder portioners, so that each of the drive motors rotates the respective feed screw a number of revolutions, corresponding to the desired dispensed weight of fodder. When any of the fodder portioners is getting empty the control unit 16 activates the drive motor 12 and opens the valve 15, so that all of the fodder portioners are filled with fodder, where- after the drive motor 12 is stopped. The fodder portioners are filled in this way repeatedly until the fodder in the container 9 has run out. A new value of the dispensing flow of fodder (or dispensing weight of fodder per revolution of the feed screw 5) is calculated when either any of the fodder portioners or the container 9 is refilled with fodder. The embodiment of the plant according to the invention shown in the drawing comprises a plurality of fodder portioners, which means a particularly advantageous utilization of the invention. However, it should be pointed out that also a plant comprising one single fodder portioner of the kind above described, which in the drawing is designated with the reference numeral 1, is within the scope of the invention according to the accompanying claims.

Claims: Claims 1. A method of measuring and portioning of fodder by means of a fodder portioner (1) provided with a dispensing device (5, 7) for dispensing an optional quantity of fodder, c h a r a c ¬ t e r i z e d i n - that the dispensing device (5, 7) is activated, - that the weight of the dispensed fodder from the fodder portioner (1) is sensed, - chat the value of a volume related variable for dispensing the fodder is registered when a given weight of the fodder dispensed from the fodder portioner is sensed, and - that on the basis of said registered value the dispensing device (5, 7) is kept activated until the desired weight of fodder has been dispensed from the fodder portioner (1). 2. A method according to claim 1, fodder being measured and portioned by means of at least one further fodder portioner (2) provided with a further dispensing device (6, 8), c h a r a c ¬ t e r i z e d i n that on the basis of said registered value, said further dispensing device (6, 8) is kept activated until the desired weight of fodder has been dispensed from said further fodder portioner (2). 3. A method according to claim 1 or 2, c h a r a c t e r i - z e i n that the volume related variable is constituted by the time for dispensing the fodder. 4. A method according to claim 1 or 2, each said dispensing device (5-8) comprising a rotatable feed screw (5, 6), c ar a c t e r i z e d i n that the volume related vari¬ able is constituted by the number of revolutions of each feed screw (5) for dispensing the fodder. 5. A plant for measuring and portioning of fodder, comprising a fodder portioner (1) provided with a dispensing device (5, 7) for dispensing an optional quantity of fodder, c h a r a c - t e r i z e d i n - chat the fodder portioner (1) is provided with a weighing means (13) for sensing the weight of dispensed fodder, - that the dispensing device (5, 7) of the fodder portioner (1) is connected to a control unit (16), which during operation of the plant is adapted to sense a volume related variable for dispensing the fodder, - that the control unit (16) is adapted to register the value of the volume related variable in response to the weighing means (13), when a given weight of dispensed fodder is sensed by the latter, and - that on the basis of said registered value the control unit (16) is adapted to control the dispensing device (5, 7), such that the desired weight of fodder is dispensed from the fodder portioner (1). 6. A plant according to claim 5, comprising at least one further fodder portioner (2) provided with a further dispensing device (6, 8), c h a r a c t e r i z e d i n that the control unit (16) is connected to said further dispensing device (6, 8) and adapted to control said further dispensing device on the basis of said registered value, such that the desired weighc of fodder is dispensed from said further fodder portioner (2). 7. A plant according to claim 5 or 6, c h a r a c t e - r i z e d i n that the control unit (16) is adapted to sense the time for dispensing the fodder. 8. A plant according to claim 5 or 6, in which each dispensing device (5-8) comprises a rotatable feed screw (5, 6), c h a - r a c t e r i z e d i n that the control unit (16) is adapted to sense the number of revolutions which each feed screw (5-8) turns during the dispensing of fodder.

Inventors: ANDERSSON SVEN, ANDERSSON, SVEN
Applicants: ALFA LAVAL AGRI INT, ALFA-LAVAL AGRICULTURE INTERNATIONAL AB
Application year: 1989
Main classification: A61K5
IPC codes: A01K5