A method of and an implement for automatically milking animals

Abstract: The invention relates to a method of automatically milking animals, comprising the following steps: measuring repeatedly or continuously a quantity which is a measure for the momentary pulse milk flow, (by pulse milk flow is meant the milk flow from a teat during a single suction phase of the milking process); controlling the duration and/or the level of the milk vacuum under the teat during the actual suction phase on the basis of the measured quantity (by suction phase is meant the time during which the teat is exposed to a vacuum during the previously mentioned pulse milk flow).

Description: The invention relates to a method of automatically milking animals, according to the preamble of claim 1. Such a method is known from EP-A-0 727 137. The invention aims at providing an alternative method. In accordance with the invention this is achieved in that the method comprises the features as specified in the characterizing part of claim 1. The above-mentioned method has the advantage of preventing the teat from being exposed for a too long period of time to the milk vacuum when the momentary pulse milk flow decreases. In this manner teat and/or udder damage is avoided. According to an inventive feature, the method comprises the following steps: storage, during the actual suction phase, of the maximum value of the pulse milk flow measured thus far or the quantity related thereto, squeezing the liner of the teat cup as soon as the momentary value of the pulse milk flow or the quantity related thereto has come below a specific, preferably adjustable threshold value. According to an inventive feature, the threshold value has a value between 60% and 80% of the maximum value of the pulse milk flow measured thus far or the quantity related thereto. In a preferred embodiment of the invention said value amounts to approximately 70%. According to again another aspect of the invention, for the purpose of avoiding teat and/or udder damage, the duration of the suction phase is limited to a value between 0.8 and 2 seconds and preferably amounts to approximately 1.4 second. According to an inventive feature, the time during which the teat is hardly exposed, if at all, to the vacuum during milking, i.e. the release phase, amounts to between 30% and 40% and preferably to approximately 35% of the duration of the suction phase. In accordance with an aspect of the invention, the maximum duration of the release phase during the main milking stage amounts to between 175 and 225 milliseconds and preferably to 200 milliseconds. According to again another inventive feature, the maximum duration of the release phase during foremilking amounts to between 30 and 100 milliseconds and preferably to 40 milliseconds. According to an inventive feature, the maximum duration of the release phase during stripping amounts to between 225 and 800 milliseconds and preferably to 400 milliseconds. According to again another inventive feature, the above-mentioned method is applied to each teat individually, so that teat and/or udder damage during milking is minimized. The invention also relates to an implement for automatically milking animals as defined in claim 11. According to an aspect of the invention, the pulse milk flow sensor comprises a conductivity sensor. According to again another inventive feature, the pulse milk flow sensor may also be constituted by an optical and/or acoustical sensor. In a particular embodiment of the invention the sensor is constituted by a small microphone. In order to obtain an optimal control of the pulsator, according to a further inventive feature, the pulse milk flow sensor is disposed in the teat cup or in the milk line system at a place located as closely as possible to the teat. According to an inventive feature, the pulse milk flow sensor is disposed in the teat cup. In a preferred embodiment of the invention the pulse milk flow sensor is arranged in the pulse chamber, i.e. the space between the liner and the outer casing of the teat cup. According to again another embodiment of the invention, the pulse milk flow sensor is disposed in or on a part of a milk line of the teat cup that is closest to the teat cup. In accordance with again another inventive feature, the implement comprises a milking robot for automatically connecting the teat cups to the teats of an animal to be milked. The invention will now be explained in further detail with reference to the accompanying drawings, in which: Figure 1 shows a teat cup in which a pulse milk flow sensor is disposed; Figure 2 shows a diagram of the pulsation curve and a diagram of the pulse milk flow curve. Figure 1 shows a teat cup 1 provided with a liner 2 and a pulse chamber 3. A pulse tube 4 is connected to the pulse chamber 3. A computer-controlled adjustable pulsator 5 is included in the pulse tube 4. Near the lower side of the teat cup 1 there is further arranged a milk line 6. In the lower part of the teat cup 1 a pulse milk flow sensor 8 is disposed in a milk collecting chamber 7. The pulse milk flow sensor 8 is connected to a computer or calculation unit via a (non-shown) line. In the present embodiment the pulse milk flow sensor comprises a microphone. With the aid of the computer and/or calculation unit the computer-controlled adjustable pulsator 5 can be controlled on the basis of the signal supplied by the pulse milk flow sensor 8. The control of the pulsator 5 will now be explained in further detail with reference to the diagrams of Figure 2. The upper diagram of Figure 2 shows schematically the pulsation curve of the pulsator for one teat. The X-axis is the time axis and the Y-axis represents the vacuum level of the milk vacuum. The lower diagram shows the momentary pulse milk flow, the X-axis being the time axis and the Y-axis representing the volume flow of milk from a teat. As indicated in Figure 2, milking can be subdivided into three stages, i.e.: A) the foremilking stage during which the relevant udder quarter is stimulated to secrete milk, B) the main milking stage during which the udder quarter easily secretes milk, and C) the stripping stage during which the "remaining milk" is milked from the udder quarter. As already mentioned before, the present invention aims at avoiding that a vacuum continues to prevail for a too long period of time under the teat when the milk flow from the relevant udder quarter has stopped. With the aid of the pulse milk flow sensor it is possible to measure continuously the changes in the pulse milk flow (Figure 2). In the lower diagram the vertical lines indicate at what points of the various consecutive pulse milk flows the quantity measured deviates each time by a specific percentage from the maximum value of that quantity measured thus far. In the present embodiment said value amounts to 70% of the maximum value of the pulse milk flow measured thus far. As shown in the upper diagram, at that moment the pulsator is activated by means of the computer in such a manner that the milk vacuum level under the teat is lowered. During lowering the milk vacuum the milk remaining thus far is yielded from the relevant udder quarter without the teat remaining exposed to the maximum vacuum. In this manner teat and/or udder damage is avoided. As shown in the two diagrams, this phase is followed by a so-called release phase during which a proper blood circulation of the teat is possible. As shown in the diagrams, during foremilking the frequency of the pulsator is relatively high in relation to the main milking and stripping stages. The high pulsation frequency stimulates the relevant udder quarter to secrete milk.

Claims: A method of automatically milking animals, comprising the following steps: measuring the momentary pulse milk flow; controlling the duration and/or the level of the milk vacuum under the teat during the actual suction phase on the basis of the measured quantity, characterized in that this method comprises the following steps: storage, during the actual suction phase, of the maximum value of the pulse milk flow measured thus far or the quantity related thereto, lowering or reducing or closing off the vacuum level of the milk vacuum as soon as the momentary value of the pulse milk flow or the quantity related thereto has come below a specific, preferably adjustable threshold value. A method as claimed in claim 1, characterized in that this method comprises the following steps: squeezing the liner of the teat cup as soon as the momentary value of the pulse milk flow or the quantity related thereto has come below the specific, preferably adjustable threshold value. A method as claimed in claim 1 or 2, characterized in that the threshold value has a value between 60% and 80% of the maximum value of the pulse milk flow measured thus far or the quantity related thereto. A method as claimed in claim 3, characterized in that the value amounts to approximately 70%. A method as claimed in any one of the preceding claims, characterized in that the duration of the suction phase is limited to a value between 0.8 and 2 seconds and preferably amounts to approximately 1.4 second. A method as claimed in any one of the preceding claims, characterized in that the time during which the teat is hardly exposed, if at all, to the vacuum during milking, i.e. the release phase, amounts to between 30% and 40% and preferably to approximately 35% of the duration of the suction phase. A method as claimed in claim 6, characterized in that the maximum duration of the release phase during the main milking stage amounts to between 175 and 225 milliseconds and preferably to 200 milliseconds. A method as claimed in any one of the preceding claims, characterized in that the maximum duration of the release phase during foremilking amounts to between 30 and 100 milliseconds and preferably to 40 milliseconds. A method as claimed in any one of the preceding claims, characterized in that the maximum duration of the release phase during stripping amounts to between 225 and 800 milliseconds and preferably to 400 milliseconds. A method as claimed in any one of the preceding claims, characterized in that the method is applied to each teat individually. An implement for automatically milking animals, said implement comprising at least one adjustable pulsator (5), at least one pulse milk flow sensor (8), means for measuring the momentary pulse milk flow, and means for controlling the duration and/or the level of the milk vacuum under the teat during the actual suction phase on the basis of the measured quantity, characterized in that the implement further comprises means for storing, during the actual suction phase, the maximum value of the pulse milk flow measured thus far or the quantity related thereto, and means for lowering or reducing or closing off the vacuum level of the milk vacuum as soon as the momentary value of the pulse milk flow or the quantity related thereto has come below a specific, preferably adjustable threshold value. An implement as claimed in claim 11, characterized in that each of the teat cups (1) of the implement for automatically milking comprises an adjustable pulsator (5) and a pulse milk flow sensor (8). An implement as claimed in claim 11 or 12, characterized in that the pulse milk flow sensor (8) comprises a conductivity sensor. An implement as claimed in claim 11 or 12, characterized in that the pulse milk flow sensor (8) is constituted by an optical and/or acoustical sensor. An implement as claimed in any one of claims 11 - 14, characterized in that the pulse milk flow sensor (8) is disposed in the teat cup (1) or in the milk line system (6) at a place located as closely as possible to the teat. An implement as claimed in claim 15, characterized in that the pulse milk flow sensor (8) is disposed in the teat cup (1). An implement as claimed in claim 15, characterized in that the pulse milk flow sensor (8) is disposed in or on a part of a milk line (6) of the teat cup (1) that is closest to the teat cup (1). An implement as claimed in any one of claims 11 - 17, characterized in that the implement comprises a milking robot for automatically connecting the teat cups (1) to the teats of an animal to be milked.

Inventors: VAN DEN BERG KAREL, VAN DEN BERG, KAREL
Applicants: MAASLAND NV, MAASLAND N.V.
Application year: 1999
Main classification: A01J5
IPC codes: A01J5