A method of determining the quantity of milk collected during a milking turn

Abstract: The invention relates to a method of determining the quantity of milk M collected during a milking turn. The method comprises the following steps: 1) discharging milk from the milkmeter, when a prefixed quantity of milk A has been collected therein; 2) stopping the discharge of milk after a fixed time (t 2 - t 1 ) has elapsed and measuring the quantity of milk C in the milkmeter; 3) measuring the quantity of milk D in the milkmeter after milking; 4) calculating in the computer the milk yield M according to: M = A + B - C + D, in which B is determined on the basis of (t 2 - t 1 ), and at least two quantity measurements in the milkmeter prior to the discharge of the milk from the milkmeter or thereafter and outside the open interval (t 2 - t 1 ) and the points of time at which these quantity measurements have been carried out.

Description: The invention relates to a method of determining the quantity of milk M collected during a milking turn, whereby, by means of a computer and a milkmeter, the quantity of milk M can be established at various points of time. A suchlike method is known. In the known method, in general, the milkmeter is partially filled with milk at the end of the milking turn. However, in some cases it might occur that the livestock comprises several high productive animals, which give so much milk during a milking turn that the capacity of the milkmeter is too small, so that milk remains in the supply line to the milkmeter. It will be obvious that this is undesirable. A possible solution for this problem is the mounting of a bigger milkmeter; however, bigger milkmeters are more expensive and take relatively much room in the milking implement. Also the cleaning of a bigger milkmeter would require more attention and more cleaning water than the cleaning of a small one. EP-A-0 081 049 discloses a milk quantity measuring device wherein milk is discharged from a measuring chamber in defined quantities during milking. The calculation of the total quantity of milk is based on the measurement of the length of time intervals corresponding to filling cycles. The determination of the duration of a filling cycle is relatively inaccurate. The device is therefore not very accurate. The invention aims at obtaining a method, in which the above-mentioned disadvantages do not occur, or are at least limited to a considerable extent. In accordance with the invention, this is achieved by means of a method comprising the steps according to the characterizing part of claim 1. By pumping away a quantity of milk during the interval of time (t 2 - t 1 ), a relatively small milk glass will be sufficient, also for high productive animals. In accordance with the method according to the invention, the quantity measurements take place prior to the discharge of the milk from the milk glass. In accordance with a further method according to the invention, the quantity measurements can also take place after the discharge of the milk from the milk glass has stopped. Also by means of these quantity measurements slope can be determined, by means of which B can be calculated as described before. The invention further relates to an implement for applying a method as described above, characterized by the features of the characterizing part of claim 4. In order to discharge the milk from the milk container in an accelerated manner, according to a further inventive feature the implement comprises a discharge line in which a computer-controlled pump is included. In a first embodiment, according to an inventive feature, the quantity meter comprises a pressure meter measuring the difference in pressure above the milk column and in the lower part thereof. The static difference in pressure is a measure for the quantity of milk present in the milk container. According to again an other inventive feature, the quantity meter comprises a float including a magnet, which moves with the milk column along a conductor, and whereby the position of the float relative to the conductor is electronically readable by means of a probe. According to again an other inventive feature, the quantity meter comprises an ultrasonic or an optic sensor, such as a laser sensor, by means of which the milk level in the milk container, and on the basis thereof the quantity of milk therein, are determined. According to a further inventive feature, the implement comprises a milking robot for automatically connecting teat cups to the teats of an animal. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to an embodiment as shown in the accompanying drawings 1 to 3. Figure 1 shows a milkmeter 1 comprising a milk glass 2, in which the milk yielded during a milking turn is collected. At the upper side of the milk glass 2 there is connected a milk supply line 3 and a vacuum line 4. At the lower side of the milk glass 2 there is a milk discharge line, in which a computer-controlled valve 6 and a controllable, computer-controlled pump 7 are included. The opening and closing of the computer-controlled valve 6 and the starting up and switching off of the computer-controlled pump 7 is effected by means of the computer 8, which is capable of supplying a signal to the valve 6 and the pump 7 via the lines 9, 10 respectively. The milkmeter 1 additionally comprises a quantity meter 11, by means of which the quantity of milk in the milk glass 2 can be determined. The quantity meter 11 includes a float 12 which moves with the milk column along a conductor 13. The conductor 13 is disposed over the entire length of the milk glass 2 and centrally therein. The float 12 includes a (non-shown) magnet which is electronically readable by means of a probe 14, disposed at the upper side of the milk glass 2. Via a line 15 the signal supplied by the probe 14 is read out by the computer 8. The position of the float 12 relative to the conductor 13 is a measure for the quantity of milk present in the milk glass 2 at a certain point of time. In Figure 1 there is furthermore indicated an alternative quantity meter 16. The alternative quantity meter 16 comprises a pressure meter 17 including a first line 18, debouching into the upper part of the milk glass 2, and a second line 19, debouching into the lower part of the milk glass 2, near the computer-controlled valve 6. By means of the pressure meter 17, the difference in pressure above the milk column and in the lower part thereof is measured. By means of a line 20 this signal is supplied to the computer 8. The static difference in pressure is a measure for the quantity of milk present in the milk glass 2 at a certain point of time. The function of the milkmeter 1 will further be explained with the aid of Figures 2 and 3. Figure 2 shows a much simplified reproduction of a diagram of the milk flow (H/T) during a milking turn. The first oblique part of the diagram shows the milk stream when the milk supply of the animal is started; the horizontal part of the diagram indicates a more or less constant milk supply of the animal and the last oblique part of the diagram represents a slow decrease of the milk supply during the milking out of the animal. By integrating the diagram of Figure 2 in time and by then setting same out against time, the diagram according to Figure 3 is obtained, in which the quantity of milk is set out in time. On the basis of Figure 3, the method of determining the quantity of milk M during a milking turn will further be explained. From the point of time t = 0, the milking turn starts and milk is collected in the milk glass 2. The computer 8 is preprogrammed in such a way that, when the milk glass 2 contains a quantity of milk A, which can be ascertained by means of the quantity meter 11, 16, the computer 8 supplies a signal to the valve 6 and the pump 7 via the lines 9, 10 respectively, so that the valve 6 and the pump 7 are put into operation. During an interval of time (t 2 - t 1 ) preprogrammed in the computer 8, milk is pumped out of the milk glass 2. Meanwhile, the flow of milk into the milk glass 2 via the milk supply line 3 is still possible. After the interval of time (t 2 - t 1 ) has elapsed, the computer-controlled valve 6 is closed and the computer-controlled pump 7 is put out of operation. At the same time the quantity of milk C then present in the milk glass 2 is determined and this data is stored in the computer 8. After it has been ascertained by means of a (non-shown) flow-sensor that there is no longer transported milk to the milk glass 2 via the milk supply line 3, the quantity of milk D in the milk glass 2 is measured and this data is stored in the computer 8. Then the milk yield M is calculated in the computer 8 according to: M = A + B - C + D. In this formula only B is unknown. However, B can be calculated on the basis of (t 2 - t 1 ) and at least two quantity measurements in the milkmeter 1 prior to the discharge of the milk from the milkmeter 1 or thereafter and on the basis of the open interval (t 2 - t 1 ) and the points of time when these quantity measurements have been carried out, which can be recorded by means of the computer 8. In the diagram of Figure 3, these two quantity measurements are indicated by x and y and the points of time when they have been carried out by t x , t y . The quantity measurements x and y and the points of time t x and t y are already recorded in the computer 8 before the quantity of milk A is collected in the milk glass 2. The quantity measurements are preferably carried out in the milk glass 2 when the quantity of milk A approaches, in order better to be able to calculate B. On the basis of the quantity measurements x and y and the points of time t x and t y , there is determined in that region a slope of the diagram, see Figure 3. On the basis of the slope and the interval of time (t 2 - t 1 ), the unknown quantity of milk B can be calculated according to the formula: B = RC(slope).(t 2 - t 1 ). By introducing B in the formula M = A + B - C + D, the total milk yield M over a milking turn can be calculated. In an alternative embodiment, a slope can also be calculated by means of at least two quantity measurements in the section between C and D in the diagram of Figure 3.

Claims: A method of determining the quantity of milk M collected during a milking turn, whereby, by means of a computer and a milkmeter, the quantity of milk M can be established at various points of time, characterized in that the method comprises the following steps: 1) the milk is discharged from the milkmeter, when a prefixed quantity of milk A has been collected therein; 2) the discharge of milk from the milkmeter is stopped after a fixed time (t 2 - t 1 ) has elapsed and the quantity of milk C in the milkmeter is then measured: 3) after it has been ascertained that the milk flow to the milkmeter has ended, the quantity of milk D in the milkmeter is measured; 4) in the computer the milk yield M is calculated according to: M = A + B - C + D, in which B is determined as (slope).(t 2 - t 1 ), wherein (slope) is determined on the basis of at least two quantity measurements in the milkmeter prior to the discharge of the milk from the milkmeter or thereafter and outside the open interval (t 2 - t 1 ) and the points of time at which these quantity measurements have been carried out. A method as claimed in claim 1, characterized in that the quantity measurements in step 4) take place prior to the discharge of the milk from the milk glass. A method as claimed in claim 1, characterized in that the quantity measurements in step 4) take place after the discharge of the milk from the milk glass has stopped. An implement for applying a method as claimed in any one of claims 1 to 3, characterized in that the implement comprises a milk container, such as a milkmeter or a milk glass, (2) including a supply line (3) and a discharge line (5) for the milk, and that a computer-controlled valve (6) is included in the discharge line (5) and a quantity meter (11, 16) is included in the milk container (2), the implement further being provided with a flow sensor for ascertaining that the milk flow to the milkmeter (2) has ended and with a computer (8). An implement as claimed in claim 4, characterized in that there is included a computer-controlled pump (7) in the discharge line. An implement as claimed in claim 4, characterized in that the quantity meter (16) comprises a pressure meter measuring the difference in pressure above the milk column and in the lower part thereof. An implement as claimed in claim 4, characterized in that the quantity meter (11, 16) comprises a float (12) including a magnet, which moves with the milk column along a conductor (13), and whereby the position of the float (12) relative to the conductor (13) is electronically readable by means of a probe (14). An implement as claimed in claim 4, characterized in that the quantity meter comprises an ultrasonic or an optic sensor, such as a laser sensor, by means of which the milk level in the milk container, and on the basis thereof the quantity of milk therein, are determined. An implement as claimed in any one of claims 4 to 8, characterized in that the implement comprises a milking robot for automatically connecting teat cups to the teats of an animal.

Inventors: VAN DEN BERG KAREL, VAN DEN BERG, KAREL
Applicants: MAASLAND NV, MAASLAND N.V.
Application year: 1996
Main classification: A01J5
IPC codes: G01F1, A01J5