WO1983000923A1

WO1983000923A1 - Method and device for measuring milk quantities

Info

Publication number: WO1983000923A1
Application number: PCT/DE1982/000170
Authority: WO
Inventors: Agrar Gmbh Alfa-Laval
Original assignee: Ordolff, Dieter
Priority date: 1981-08-28
Filing date: 1982-08-27
Publication date: 1983-03-17
Also published as: DE3134079A1; EP0088090A1; JPS58501394A

Abstract

The method is intended to measure milk quantities continuously flowing into a measuring apparatus as a mixture of milk and air. According to this method, the dynamic force which results from the deviation of the milk-air mixture is measured, said force being independent of the dissolved air fraction. The device used in this method is characterized in that in the measuring container there is provided a duct wherein the milk-air mixture circulates, and which is provided with a deviation channel pivotably mounted in a vertical position on a center point on which it may oscillate without friction.

Description

METHOD AND DEVICE FOR MEASURING QUANTITIES OF MILK The invention relates to a method for measuring quantities of milk which continuously flow through a measuring device as an air milk mixture.

In addition, the invention relates to a device for carrying out a method for measuring milk quantities which continuously flow through a measuring vessel as an air milk mixture.

For the measurement of milk quantities, milk quantity meters are known, some of which work discontinuously and others which operate discontinuously. Milk quantity measuring devices work, for example, with a dipstick and a direction table for self-checking of the delivery quantity. However, these devices have the disadvantage that correspondingly complicated conversions are required to determine the volume or the weight. In particular with ma machine milking processes, one is particularly interested in continuous measuring processes. Since milk is obtained in a continuous flow especially when using tubular milking systems, the interruption of this flow for the purpose of quantity measurement means an additional workload which has a productivity-reducing effect. However, some of the recommended measuring devices for measuring milk quantities work quite imprecisely, and others, in turn, require quite a lot of equipment. The inaccuracy of the known discontinuous methods essentially stems from the fact that they are based on volume measurements, so that the air fraction dissolved in the milk leads to a falsification of the measurement result. Mixed quantities of milk and air are measured on these devices. Another continuous method is based on measuring the flow time in which the milk flows through a measuring line located between two containers. The result of the time measurement can be registered as a quantity display. The process has the advantage that it can

Replacement sheet milk quantities works exactly. Only the pure amount of milk from which the air particles have already escaped is measured. In this flow measuring method, however, it is crucial that the flow measuring section is completely filled with milk at all times. Appropriate measures must therefore be taken to ensure a constant pressure drop in the measuring line. Additional milk flow monitoring is therefore necessary. Continuous measuring methods are also known in which the milk quantities are measured with the aid of deflections of the milk flow. For example, the milk flow is directed onto a baffle plate, the deflection of which is a measure of the size of the milk flow that is deflected at it. In another variant, the milk flow is passed through a U-tube that is excited in the middle of its yoke by a vibration, so that the two legs swing around their fixed ^'.en restraints. The milk flow deflected by the U-tube causes the leg located on the milk inlet side to vibrate differently than the leg on the milk outlet side. The difference between the two vibrations is a measure of the milk flow that flows through the U-tube. Both apparatuses have the disadvantage that the milk particles are subjected to large accelerations or large decelerations, so that the structure of the milk particles suffers damage and the quality of the milk thus decreases.

The object of the present invention is therefore to improve methods for continuous milk measurement in such a way that an accurate detection of milk quantities is ensured while at the same time gentle treatment of the milk and can be carried out economically.

This object is achieved in that the dynamic force generated by U steering the air milk mixture

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Spare sheet is measured, which is independent of the proportion of dissolved air.

A milk quantity measurement carried out according to this method has the advantage that the milk quantities flowing through are recorded without the air dissolved in the milk playing a role in this. This is achieved in that the force of the milk flow is measured, which it experiences during a deflection. This force is proportional to the mass and the square of the speed and inversely proportional to the radius of the deflection. The force is converted into a corresponding deflection, which experiences a guide tube with oscillating bearings and through which the air-milk mixture flows, with an attached guide channel. Since the mass of the air dissolved in the milk flow is negligible compared to the mass of the milk, it does not matter with this measuring method that the milk flowing through is completely degassed by entrained air particles. The deflections of the guide tube from its initial position are therefore a measure of the amount of milk flowing through. The deflection of the guide tube from its initial position, which occurs due to the deflection of the milk flow, can be measured in various ways. For example, one can think of purely mechanical transmission options. In the method according to the invention, however, an electronic transmission of the deflection is particularly provided. This has the advantage that the measured value can be tapped from the outside without contact. A precise milk quantity detection can also be carried out with small milk quantities, so that precise measurement results can still be achieved even with a small milk output. can.

The measured values can be used, for example, to control the milking machine in accordance with the measured values

He result from the flow rate measurement. In this way it can be started up or switched off smoothly with small flow rates. The milk flow curve can be extended by appropriate control of the milking machine.

Many of the systems and devices for continuous milk quantity measurements that have become known work inaccurately and, in particular, do not give any impulses that can be used in the sense of recording and registering milk quantity measurements. The rough operating conditions of a cowshed are sometimes noticeable as significant measurement errors.

A further object of the invention is therefore to improve the device of the type mentioned at the outset in such a way that it enables accurate measurement and registration of milk quantity measurements, is largely insensitive to faults and can also easily be retrofitted.

This object is achieved according to the invention in that a guide tube through which the air-milk mixture flows and with a deflection channel attached is pivoted in a frictionless and swinging manner in its upright position on a tip.

This system is limited to a few parts that must be arranged in the milk flow. The milk flows through them so that they are easy to clean.

Large residues of milk do not remain in the device. The device is also easy to retrofit and can therefore also be used in already installed milking systems. It is easy to use and easy to maintain.

OMPI atzbl t ^IP0 Further details of the invention result from the following detailed description and the attached drawings, in which some preferred embodiments of the invention are illustrated for example.

The drawings show:

Figure 1; :

1 shows a schematic representation of a device for measuring milk quantity,

Figure 2Ϊ

1 shows a schematic representation of another device for measuring the amount of milk,

Figure 3: ^*

2 shows a circuit diagram for measuring the deflection with the aid of magnet-sensitive semiconductors,

Figure 4:

a circuit diagram for the measurement of the deflection with the aid of a sensor located in the magnetic field and for the temperature correction and

Figure 5;

a circuit diagram of a non-linear amplifier.

^{Replacement sheet} for ^OMPI P The method according to the invention is expediently carried out using a device shown in FIG. 1, from which the internal structure emerges. A float 2 is arranged in a housing 1. This moves in the upper part of the housing 1, which is designed as a float housing 3. The milk enters the guide tube 4 from the float housing 3 with the float 2 raised. The milk falls out of the guide tube 4 due to its own weight into a deflection channel 5 which is open at the top. The flow of milk is deflected through a certain angle in the deflection channel 5.

The guide tube 4 with the attached guide channel 5 is pivotally mounted on a tip 6. In its upright position, the guide tube 4 can be held in various ways, for example by holding magnets 7, 8, 9 and 10, which are fastened both to the guide tube 4 and to a discharge housing 11 surrounding the guide tube 4; (Figure 2) in another embodiment of the method according to the invention, however, it is also possible to mount holding magnets 9, 10 only on one side of the guide tube 4 and the discharge housing 11, while on the other side the guide tube 4 is pressed against a cutting edge bearing 12 , which extends approximately over the entire length of the guide tube 4.

The magnetic bearing with the help of the holding magnets also has the advantage that the guide tube 4 is swinging. Although the measurement method is independent of the air content of the milk flowing through, there is an air suction device 13 on the float housing 3, through which the essential part of the air which is supplied by the air milk mixture is extracted.

OMP

REPLACEMENT BfcATT Λ. WIP The air drawn off via the air suction 13 is introduced into the discharge housing 11 via a suction opening 14 and leaves the housing 1 via an outlet opening 15 in the direction of an air cutter. The bearing of the guide tube 4 on the tip 6 has the advantage of a low frictional resistance. In the vertical basic position, the cutting edge bearing 12, against which the guide tube 4 is pulled, runs vertically and thus parallel to the central axis of the guide tube 4. The tip 6 can also be provided in the upper part of the cutting edge bearing 12. The bearings of the guide tube 4 described, however, represent only two exemplary embodiments selected from many possibilities. The guide tube 4 can also be stored in another way and held in its initial position.

The float 2 has the advantage of dampening the milk flow entering the guide tube 4. As a result, the milk only falls from the float housing 3 into the guide tube 4 due to its own weight. The float 2 controls the passage gap in the direction of the guide tube 4. A switch contact 16 can also be connected to the float 2, which ensures that that the milking machine is switched on or off in a certain float position. This start-stop circuit can be seen as a control of the milking machine according to the flow. The float 2 thus has a double function as an on-off switch on the one hand and as a regulator for the flow in the direction of the guide tube 4 on the other.

In another embodiment of the invention, the inlet into the guide tube 4 can also be damped with a constant gap 17.

The entry into such a gap can take place with the aid of a cone which tapers in the direction of an inlet 18.

O H

Replacement _b latt, WIPO In a further embodiment of the invention, it is also conceivable that the milk air mixture entering the float housing 3 through the inlet 18 enters the guide tube 4 directly, ie without damping by the float or cone. When the air is reintroduced in the area of the suction opening 14, care must be taken that the air flow is introduced into the housing 1 in such a way that it does not generate any additional torque in the guide tube 4.

The SchwingerS stem from guide tube 4 and guide channel 5 need not be arranged in the middle of the discharge housing 11. A lateral arrangement improves the spatial utilization of the discharge housing 11.

The deflection channel 5 should be open at the top, so that any existing foam has the possibility of being formed on the milk flow without impeding the milk flow. In addition, when the milk flows through the deflection channel, 5 air portions can be extracted from the milk from the open channel. In the case of large quantities of milk to be expected, the deflection channel 5 should be provided with a large diameter, and in the case of small quantities of milk with a smaller diameter. The diameter selected in each case is used as a constant in the calculation of the quantity of milk flowing through.

In a preferred embodiment of the invention, the deflection of the guide tube 4 resulting from the deflection of the milk flow is measured contactlessly by changing the magnetic field. This is possible, for example, in that two magnet-sensitive semiconductors 19, 20 designed as differential field plates are controlled by a magnet 21 attached to the guide tube 4. The resistance of the semiconductors is then the strength

Spare sheet of the magnetic field proportional.

If the magnetic field changes, the resistance changes in the same ratio. The magnetically sensitive semiconductors 19, 20 are fed from a voltage supply 22, and the measuring voltage can be tapped in accordance with the resistance. In this respect, the voltage is proportional to the magnetic field and thus to the deflection of the guide tube 4 (see FIG. 3).

In the example shown in FIG. 4, two poles 23, 24 of a magnet 32 are fastened next to one another on the guide tube 4, so that on the one hand the south pole and on the other hand the north pole point in the direction of a sensor 25. When the guide tube 4 is deflected due to the milk flowing through the deflection channel 5, depending on the attachment of the magnet 32, either the south pole 23 increasingly gains influence if the north pole 24 was previously opposite the sensor 25 or, conversely, the north pole 24. if the south pole 23 previously faced the sensor 25. This arrangement has the advantage that it requires little effort and in particular the electronic further processing of the measured value is possible with an integrated amplifier 26, which is customary in the trade.

In practical operation, the entire device is exposed to large temperature fluctuations. The influence of temperature can be particularly great in the critical operating range if a lot of milk flows that has the body temperature of the cow (37 ° Celsius). In contrast, the device warms up less at low milk flow rates. In these cases there may be considerable deviations in measured values due to the respective device temperature if no measure for temperature correction is provided.

OMPI

Spare sheet The electronics therefore require compensation in order to reduce the sensitivity to temperature. For this purpose, the zero point of the sensor 25 is set externally with the aid of a corresponding voltage. The exact setting of this voltage is carried out with the aid of a potentiometer 27. A temperature-sensitive resistor 28 generates a counter voltage when the temperature changes, which counteracts the influence of temperature (cf. FIG. 4).

The output signal of the integrated amplifier 26 is, according to the input signal, not linear. To produce a linearity, the integrated amplifier 26 is followed by a non-linear amplifier 29 which forms a straight characteristic curve from the output characteristic curve of the differential field plates 20, 21 or the sensor 25 which is curved due to the physical basis of the measurement method described here. The amplifier 29 is connected to a non-linear negative feedback 30, 31 which regulates the gain depending on the input signal. This arrangement can be used either simply or in parallel if required. With a parallel arrangement, each branch can be set individually.

The analog voltage is then converted into digital pulses, the frequency of which is proportional to the voltage applied. The number of pulses is then integrated over time. The error accuracy achieved in this way is 1 1/2 to 2%.

tt

Claims

Claims:

^" 1. Method for measuring quantities of milk which continuously flow through a measuring vessel as an air milk mixture, characterized in that the dynamic force resulting from deflection of the air milk mixture is measured, which is independent of the proportion of dissolved air.

2. The method according to claim 1, characterized in that the force is converted into a corresponding deflection of a movably Lager¬ th guide tube (4) with attached deflection channel (5).

3. The method according to claim 1 and 2, characterized in that the deflection is transmitted purely mechanically as a measured value.

4. The method according to claim 1 and 2, characterized in that the value of the deflection is measured electronically by changing a magnetic field and an electric voltage proportional to the magnetic field change is formed.

5. The method according to claim 1 to 4, characterized in that the electrical voltage is converted into digital pulses, the frequency of which is proportional to the voltage, and the number of digital pulses is integrated over time.

6. The method according to claim 4 and 5, characterized in that. that the influence of temperature changes is compensated for by generating a counter voltage.

Spare sheet

7. The method according to claim 1 to 6, characterized in that a substantial part of the air is sucked out of the air milk mixture before the measurement and is introduced again after the measurement.

8. The method according to claim 1 to 7, characterized in that the air milk mixture is supplied to the guide tube (4) undamped.

9. The method according to claim 1 to 7, characterized in that the air milk mixture is first steamed before being introduced into the guide tube (4).

10. The method according to claim 9, characterized in that the milk flow in the guide tube (4) by a float (2) is regulated ge and a milk supplying milk machine is controlled in dependence on float positions.

11. A device for carrying out a method for measuring the amount of milk which continuously flows through a measuring vessel as an air-milk mixture according to claims 1 to 10, characterized in that in the measuring vessel (1) a guide tube (4) through which the air-milk mixture flows has been attached Deflection channel (5) is pivotally and frictionally mounted in its upright position on a tip (6).

12. The apparatus according to claim 11, characterized in that the guide tube (4) by means of holding magnets (7 to 10) which are attached to the guide tube (4) and to the discharge housing (11) held in its upright position in the starting position -, becomes.

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Replacement sheet Λ. IPO

13. The apparatus of claim 12 ,. characterized in that ^' holding magnets (9, 10) are attached only on one side of the guide tube (4) and the discharge housing (11), while on the

-Other side of the guide tube (4) is provided with cutting edge bearing (12).

14. The apparatus according to claim 11 to 13, characterized in that the float housing (3) contains a milk flow-damping float (2), which is provided with a switching contact (16) hen.

15. The apparatus according to claim 11 to 14, characterized in that a constant gap (17) is provided for damping the milk flow before the milk flow enters the guide tube (4), in front of which a cone (33) is arranged , which tapers towards the inlet (18).

16. The apparatus according to claim 11 to 15, characterized gekennzeich¬ net that the guide tube (4) and the deflection channel (5) form a Schwin¬ gersystem, which is laterally in the Ab-Leitgehäuse (11) an¬, and that Deflection channel (5) has an upwardly open gap for the escape of foam and air.

17. The apparatus according to claim 11 to 16, characterized in that two non-contact measurement of the deflection designed as Diff¬ rentialfeldplatte magnetically sensitive semiconductors (19, 20) are provided, and that on the guide tube (4) a controlling magnet (21) attached is.

18. The apparatus according to claim 11 to 16, characterized in that a magnet (32) on the guide tube (4) is fixed, the two poles (23, 24) in the direction of a magnetically sensitive sensor (25) which on the discharge housing (11) is attached.

^ E

OMPI

Replacement bialt Λ. WΓPO

19. The apparatus of claim 11 to 18, characterized gekennzeich¬ net that an integrated amplifier (26) for digital further processing of the analog voltage signal is provided, which is connected to a temperature-sensitive resistor (28) for generating a temperature-dependent counter voltage and the one non-linear amplifier (29) to compensate for the non-linearity of the input signal.

20. The apparatus of claim 11 to 19, characterized gekennzeich¬ net that the non-linear amplifier (29) is followed by at least one non-linear negative feedback (30, 31) for regulating the gain depending on the input signal and that in two parallel to each other switched non-linear counter-couplings (30, 31) each can be set individually and independently of one another.

Substitute b.o-Λ