WO1993014625A1

WO1993014625A1 - Automatic milking apparatus

Info

Publication number: WO1993014625A1
Application number: PCT/GB1993/000162
Authority: WO
Inventors: Tony Kenneth Griffin
Original assignee: British Technology Group Ltd.
Priority date: 1992-01-29
Filing date: 1993-01-26
Publication date: 1993-08-05
Also published as: GB2263612A; GB9413012D0; GB9201912D0; GB2277671A; GB2277671B

Abstract

An automatic milking apparatus, including a pulsator tap (26) or the like, and a control unit (38) effective to vary the milking pulsation characteristic in sympathy with the opening and closing of the liners.

Description

AUTOMATIC MILKING APPARATUS

The present invention relates to automatic milking apparatus. The basic components of a milking Installation, at least as far as the present Invention is concerned, are (1) a cluster of four teat cups Including (2) a clawplece, (3) a suction pump and (4) a pulsator. Each teat cup comprises a rigid outer casing containing a flexible liner which fits over one of the cow's teats. A pressure of approximately 50 kPa below atmosphere is continuously applied to the "core" space enclosed by the liner. Apart from encouraging a flow of milk into the core space, this negative pressure is also effective to clamp the teat liner onto the teat - this effect being referred to as "adhesion".

Thanks to the action of the pulsator, the pressure applied to the annular "pulsation" space between the liner and the rigid casing is alternated, typically once every second, between 50 kPa (I.e. below atmospheric) and 100 kPa (atmospheric).

At the 50 kPa pulsation value, there is zero pressure differential across the liner walls so that the liner is open enabling milk to be sucked from the teat into the core space. From the core space the milk is drawn down a flexible "short milk" tube into one of the four tubular "nipples" projecting upwardly from the Interior volume of a special junction called a "clawpiece". From the clawpiece, the milk is drawn through an outlet nipple via a "long milk" tube to an appropriate receptacle or pipeline. The other three nipples of the clawpiece are connected to similar teat cups and thence to the other teats of the cow's udder.

At the 100 kPa pressure value in the annular pulsation space, the liner collapses onto the teat and the resulting pressure applied to the teat causes cessation of milk flow and provides the massage of the teat found necessary to encourage blood circulation in the teat. Normally, the "massage" (zero flow) phase of the milking cycle is shorter than the "milk-flow" phase. In what may be termed conventional machine milking, a small air bleed Is provided in the clawpiece, or short milk tubes, to assist the transport of milk from the cluster to the receptacle or pipeline. This system has been used commercially more or less unchanged for over sixty years. More recently, one-way valves have been used in the base of the liner, in the short milk tubes, or in the clawpiece to prevent the flow back of milk towards the teat. These modifications have been used to control udder disease and when operated without airbleeds provide a new method of milking called "hydraulic" milking which has certain performance advantages (see National Research Development Corporation Patents 2159685 and 2192324).

It is the practice in known hydraulic and conventional machine milking assemblies, to have regular pulsation settings. These are controlled by a master unit sending the same electric signals to provide synchronous switching of a number of electrically-operated valves or "taps" (one at each milking point in the assembly) between a first position in which the taps connect a 50 kPa air line to the relevant pulsator volume and a second position in which they vent these volumes to atmosphere. However, depending on the size of the teat orifice and at what stage the cow is in Its lactation milking period, the milking rate of any particular cow can vary between 0 and 15 Kg/min and the known pre-set pulsation regime can take no account of these Individual variations in milking rate. The result is that in such cases, sometimes the liner is open in the milking cycle when it should Ideally be collapsed and sometimes the liner is closed in the milking cycle when it should ideally be open. It has been found, however, that in both hydraulic and conventional machine milking, the effectiveness of pulsation In providing teat massage and optimised milking performance can only be achieved when the liner both collapses and opens in a single pulsation cycle and it is therefore impossible to achieve optimum pulsation effectiveness with the known systems in practice. An object of the present Invention is to provide an automatic milking system in which the pulsation effectiveness has been Improved.

According to a first aspect of the present Invention, in a method of machine milking, the milking pulsation characteristic for each cow is automatically varied during each milking in sympathy with the opening and closing of the liners attached to the teats of that cow.

The term "pulsation characteristic" as used above and throughout the specification (including the claims) is to be

Interpreted as meaning the manner in which the pulsation pressure values vary with time e.g. as Illustrated in a pressure v. time plot of the pressure values in the pulsation volume of the liner concerned.

According to a second aspect of the present Invention, an automatic milking apparatus Includes control means effective to switch the pulsator from one operational mode to the other in sympathy with the opening and closing of the liners attached to the teats of that cow.

Conveniently, the control means responds to the volume or movement of air being expanded or contracted in the pulsation spaces of the liners and adjusts the pulsation switching characteristic in sympathy with the opening and closing of the liners so as, as nearly as possible in the circumstances, to fully collapse and open the liners in a single pulsation cycle.

Conveniently, volume-responsive control means Include a piston and cylinder device or like displacement mechanism e.g. a moving diaphragm or bellows device.

Conveniently, the displacement mechanism is driven by air from or for the pulsation spaces of the associated liners, the supply or removal of which air is supplemented, in the case of sluggishly-moving liners, by an additional supply of air or vacuum to the displacement mechanism.

Conveniently, the pulsation characteristic is electrically controlled by two contact switches activated by the displacement mechanism at the extremes of Its travel. Alternatively, the pulsation characteristic may be pneumatically controlled by a slide valve assembly operated by the displacement mechanism at the extremes of its travel.

Conveniently, where a movement-responsive control means is used, this control means includes a pair of air-flow bobbins which in the absence of a flow of air to or from the liner pulsation volume, occupy positions in which they are effective to switch the pulsator from one operational mode to the other.

An alternative movement-responsive control means Includes a hot wire galvanometer which operates In the air flow from or for the liner pulsation volume to vary the pulsation characteristic by producing a temperature-related electric current which will peak when the liners open or close to switch the pulsator from one operational mode to the other.

Another alternative envisaged for the movement-responsive control means is a magnetic field-producing turbine driven by the movement of air to or from the liner which turbine comes to rest when the liners open or close to cause a change in the magnetic field around the turbine thereby to switch the pulsator from one operational mode to the other.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying, somewhat diagrammatic, drawings in which:

Figure 1 is a simplified diagrammatic view illustrating part of a typical milking installation according to the present invention;

Figure 2 is a somewhat diagrammatic longitudinal section through a piston and cylinder-type control unit for use in the Installation of Figure 1;

Figure 3 is a longitudinal section through a bellows-type alternative control unit;

Figure 4 is a longitudinal section through a diaphragm-type alternative control unit; Figure 5A is a longitudinal section through a volume-responsive control unit generally similar to the unit shown in Figure 2 but using pneumatic switching Instead of the electric switching of the Figure 2 unit;

Figure 5B is a detail of an alternative control unit to the one shown In Figure 5A, Figures 5A and 5B being collectively referred to below as "Figure 5";

Figure 6 is a longitudinal section through a double bobbin-type alternative control unit;

Figure 7 is a longitudinal section through a hot wire galvanometer-type control unit; and

Figure 8 is a side view of a turbine-type alternative control unit.

Thus referring first to Figure 1, this shows part of a milking Installation having two milking units 8. In practice, there will typically be ten or so such units in an average-sized milking Installation.

Each unit 8 consists basically of four teat cups 10, a clawpiece 12 having the usual pulsation distributor cap (not shown), four short milk tubes 14 connecting the teat cups to the clawpiece, and a long milk tube 16 taking the milk from the clawpiece to a recorder jar 18 (or other milk measuring device). One-way milk flow valves (not shown) may be sited in the liners, the short milk tubes or the clawpieces to provide a uni-directional milk flow system.

The bottoms of the recorder jars 18 are shown connected to a common milk conveyanci ng pipeline 20 although in an alternative embodiment (not shown), the jars 18 (or equivalent) are omitted and the long milk tubes 16 lead directly to the common milk conveyancing pipeline 20.

Reference numeral 22 Indicates the milking vacuum pipeline, while reference numeral 24 Indicates a 50 kPa air line for the clawpiece pulsator tap 26.

As shown, the common milk conveyancing pipeline 20 leads to a receiver vessel 28 and in operation of the installation, a milk pump 30 operates to draw milk from the vessel 28 for discharge, via pipeline 32, to a bulk tank (not shown).

As usual, the installation further Includes a sanitary trap 34, a vacuum regulator 35, interceptor 36, and a vacuum pump 37, whilst in accordance with the present invention a liner-responsive control unit 38 is fitted in the air tube between the pulsation distributor cap of each clawpiece 8 and the associated pulsator tap 26.

Figure 2 shows a currently preferred form of control unit 38 including a piston/cylinder arrangement 41/42 and two two-way microswltches 43,44. These latter are operated by the piston 41 on reaching one or other end of the 20 cm long cylinder 42, to direct a 12-volt supply current from a central transformer (not shown) to each pulsator tap 26. No master pulsator is required.

Reference numerals 45,46 respectively Indicate Inlet-outlet ports in the end faces of the 8 cm diameter cylinder for respective connection with pulsator tap 26 and the pulsator distributor cap of clawpiece 12.

The clawpiece end of the cylinder 42 is permanently vented to atmosphere at vent 47 and to the 50 kPa air line 24 at vent 48.

In its de-energised state, the pulsator tap 26 allows the 50 kPa pressure from air line 24 access to the space above the piston 41 thereby causing the piston 41 to be drawn from the position shown in Figure 2 to the top of its cylinder 42. There the piston operates the upper two-way microswitch 43 which energises the pulsator tap to vent it to atmosphere and allow air at 100 kPa to enter above the piston 41. The expanding air above the piston 41 and the collapsing liners In cups 10, then draws the piston 41 down the cylinder 42. Any excess of air below the piston 41 that is not drawn off by virtue of the liner's collapsing e.g. as may be the case when the cow is at an unfavourable stage in its lactation cycle, for example, is Instead drawn off via the 50 kPa bleed 48 so that the piston 41 can still continue towards the bottom of the cylinder 42. On reaching the cylinder bottom, the piston 41 operates the lower two-way microswitch 44 to de-energise the pulsator tap and connect the ½ kPa airline pressure to the space above piston 41. This causes the piston 41 to rise again in the cylinder 42, thereby expanding the volume of air in the system (aided by the opening liners). The atmospheric bleed 47 will compensate for any shortfall In the volume of air required to take the piston 41 to the top of Its cylinder where it operates the microswitch 43 to restart once more the cycle described above.

To summarise the operation of control unit 38, it will be seen that 1f the liners in cups 10 open and close sluggishly, then compared with a freely opening and closing regime, the microswitches 43,44 will be operated more slowly so as to match, or more nearly match, the liner core pulsation characteristic to the opening and closing movement of the liners actually taking place in practice. This ensures that even under adverse milking conditions, the applied pulsation pressures will tend towards more effective liner movement as regards teat massage and optimised milking performance.

Although not critical to the successful operation of the control unit, it will be appreciated that the design of both the volume of the cylinder 42 not taken up by the piston 41, and also the sizes of the bleeds 47 and 48, can beneficially be tailored to the volume of the pulsation system in a given type of cluster assembly and the type of milking (conventional or hydraulic) respectively.

Figure 3 shows an alternative control unit in which the electric switches 43,44 are operated by the bottom 49 of a bellows 50 replacing the piston 41 of the earlier control unit. The absence of a piston in this design allows the cylinder length to be reduced to 12 cm or so but the cylinder diameter remains at 8 cm.

Figure 4 shows another design of control unit in which the cylinder 42 is replaced by a discus-shaped housing 51 and the piston 41 (or bellows 50) is replaced by a soft butyl rubber diaphragm 52 secured in the diametral plane of the housing 51. Typically, the dimensions of housing 51 are 20 cm diameter and 4 cm maximum depth.

The drawing assumes a situation in which equal pressures act on either side of the diaphragm 52. In use, the diaphragm will deform in response to pressure differentials across the diaphragm to adopt configurations in which it will operate the switches 43,44 as above described with reference to the Figure 2 embodiment.

In the control unit of Figure 5, the two electric switches 43,44 of the earlier embodiments are replaced by a single switch in the form of a pneumatic slide valve 54 and the pulsator tap 26 is omitted from the Figure 1 installation.

During operation of the control unit, the slide valve 54 is moved between two alternative positions by the up and down motion of the piston 41 which is joined with the lower end of the valve by an articulated linkage 56.

As It moves upwards from the Intermediate position shown in Figure 5A towards the inlet port 45, for example, the piston 41 will first fully collapse linkage 56 after which further upward movement of the piston will urge the slide valve 54 from the illustrated lower position (in which it blocks off a connection 57 to atmosphere) to its upper position in which it will block off the upper connection 58 to airline 24 (at half atmospheric).

During the subsequent return motion of the piston, the slide valve will, remain In Its uppermost position until the piston has almost completed its downward travel at which point the linkage 56 will have been expanded to Us fully cranked configuration so that in the closing stages of Its downward motion, the piston will pull the slide valve down to its illustrated lower position allowing air at half atmospheric pressure once again to enter the cylinder via connection 58 and inlet port 45. Details of an alternative linkage are illustrated in

Figure 5B which shows how a tension spring 60 is provided across the elbow of the articulated linkage 56 to ensure that the slide is moved from Its upper to Its lower position at the bottom of the piston's travel. Similarly, an optional compression spring abutment element 61 provided at one or other end of the linkage 56 will ensure that slide valve 54 moves upwardly in the reverse direction when the piston reaches the top of Its travel.

To ensure that the slide valve is positively held in place at the two extremes of its travel, an over-dead-centre compression sprung pivoted element 62 is provided between the valve member 54 and the housing 63.

As an alternative to the arrangement of Figure 5A, Figure 5B shows part of a design in which the distal end of the compression-sprung element 62 carries a cross-member 66 housed in a slot 67 in the slide valve 54 and the spring elements 60,61 of the previous design are replaced by two compression springs 69,70 acting between this cross-member and other parts of the housing 63.

In marked contrast to the embodiments of Figures 1 to 5 which are generally similar in their mode of operation, Figure 6 Illustrates a completely different type of movement responsive control in which two downwardly-tapering fluted bobbins 72,73 are shown supported on spider-type seatings 75,76 in the adjacent vertical limbs of a switch-back shaped pipe portion located between the clawpiece 12 and the pulsator tap 26 in the installation of Figure 1.

As shown in Figure 6, the two pipe sections above seatings 75,76 are of increased internal diameter so that the upward displacement of the relevant bobbin into that section will facilitate an upward flow of air through the pipework.

The bobbins 72,73 and their seatings 75,76 are electrically conductive and in the positions Illustrated in Figure 6 (zero air flow to or from the liner pulsation volume) they complete a twelve volt switching circuit 78 to the pulsation tap 26 to change the pulsation pressure from atmospheric to half atmospheric or vice versa as the case may be.

Suppose, for example, that on the bobbins returning to the position illustrated in Figure 6, the pulsation pressure is switched to atmospheric. This results in an overall downward flow of air through the control unit lifting bobbin 73 from its seating and thereby breaking the switching circuit to tap 26.

At the end of the atmospheric phase of the pulsation cycle, the air flow will temporarily cease, and the bobbins 73 will return under gravity to its illustrated position to complete the switching circuit to the tap 26 and move it to Its half-atmosphere position (say). The counter-flow of air through the unit will this time lift bobbin 72 from its seating so that again the switching circuit Is broken. On completion of the vacuum stage of the pulsation cycle, however, air flow through the unit will temporarily cease, bobbin 72 will return to Its Illustrated position and the circuit will be completed to switch tap 26 back to its Initial position whereupon the cycle is repeated.

As already indicated in the introductory portions of thi s specifi cation, an al ternative to using volumetric displacement, i s to detect movement of air di splaced by the liner e.g. using a hot wire galvanometer devi ce as depi cted dlagrammati cal ly in Figure 7.

In essence, this comprises a hot wire 80 protruding from the galvanometer 81 Into the pipework between the liner and the tap 26. The device will respond to a cessation in the (wire-cooling) air-flow through the pipework by an Increase in temperature in the wire 80 which in turn results in a greater electric current being generated in the galvanometer circuitry. This current is fed via an appropriate connection 82 to a microchip control circuit (not shown) which responds to current values above a certain reference level to switch the tap 26 and change the pulsation valve from atmospheric to half atmospheric (say) to promote a counterflow of air through the pipework. As before, when this counterflow ceases, the temperature of wire 80 rises and the tap 26 is switched back to its original value so that the cycle repeats.

Another air displacement control system is Illustrated in Figure 8 in which an aluminium turbine 83 Is mounted in the pipework 84 between the liner and the pulsation tap so as to rotate only in response to airflows through the pipework (in either direction). Instead of aluminium, the turbine 83 may be constructed of any other non-magnetic material e.g. a plastics material .

Blading of opposite hand on the two end faces of the turbine, enables it to turn (in opposite rotational senses) in response to a flow of air in either direction through the pipework 84.

The turbine carries at Its periphery, a series of bar magnets 85 which on rotation of the turbine produce a moving magnetic field effective to displace a pivoted contact element 86 away from the central circuit-completing position shown in Figure 8 and Into contact with one or other of two stops 87,88.

Thus, as before, only when the atmospheric or half-atmospheric phase of the pulsation cycle has been completed, will the contact element 86 swing back to complete the switching circuit 90 to the pulsator tap 26 to begin the next phase of the cycle.

The liner displacement and air movement systems described above, all rely on the novel idea of using liner-responsive control signals to vary the switching characteristics of a pulsator tap individually for each cow and during each milking. The basic aim is to provide effective pulsation to the teat liners by operating the pulsator tap to provide the necessary time (but preferably no more than the necessary time), to open and close the liners. The system described with respect to the accompanying drawings cannot provide absolute or precise pulsation characteristics because the teat cups for any one cow are not treated individually but as a group. Moreover, the liners may not move in some cases despite the increased duration of the particular pressure applied to the pulsation space. Despite these limitations, the systems of the present invention will at least tend towards the ideal of effective pulsation and will have significant benefits over a conventional pulsation system applied to all cows at all times.

The term "cow" used throughout the above text and in the following claims should be broadly Interpreted as Including any commercial milk-producing species Including goats and sheep.

Claims

1. A method of machine milking in which the milking pulsation characteristic for each cow is automatically varied during each milking in sympathy with the opening and closing of the liners attached to the teats of that cow.

2. An automatic milking apparatus Including control means effective to switch the pulsator from one operational mode to the other in sympathy with the opening and closing of the liners attached to the teats of the cow.

3. An apparatus as claimed In Claim 2 in which the control means responds to the volume or movement of air being expanded or contracted in the pulsation spaces of the liners and adjusts the pulsation switching characteristic in sympathy with the opening and closing of the liners so as, as nearly as possible in the circumstances, to fully collapse and open the liners in a single pulsation cycle.

4. An apparatus as claimed In Claim 3 in which the control means is a volume-responsive control means and Includes a piston and cylinder device or like displacement mechanism.

5. An apparatus as claimed in Claim 4 in which the displacement mechanism is driven by air from or for the pulsation spaces of the associated liners, the supply or removal of which air is supplemented, in the case of sluggishly-moving liners, by an additional supply of air or vacuum to the displacement mechanism.

6. An apparatus as claimed in Claim 4 or Claim 5 in which the pulsation characteristic is electrically controlled by two contact switches activated by the displacement mechanism at the extremes of Its travel.

7. An apparatus as claimed in Claim 4 or Claim 5 in which the pulsation frequency is pneumatically controlled by a slide valve assembly operated by the displacement mechanism at the extremes of its travel.

8. An apparatus as claimed in Claim 2 or Claim 3 in which the control means is a movement-responsive control means and Includes a pair of a1r-flow bobbins which in the absence of a flow of air to or from the liner pulsation volume, occupy positions in which they are effective to switch the pulsator from one operational mode to the other.

9. An apparatus as claimed in Claim 2 or Claim 3 in which the control means is a movement-responsive control means and includes a hot wire galvanometer which operates in the air flow from or for the liner pulsation volume to vary the pulsation frequency characteristic by producing a temperature-related electric current which will peak when the liners open or close to switch the pulsator from one operational mode to the other.

10. An apparatus as claimed in Claim 2 or Claim 3 in which the control means is a movement-responsive control means comprising a magnetic field-producing turbine driven by the movement of air to or from the liner pulsation volume which turbine comes to rest when the liners open or close to cause a change in the magnetic field around the turbine thereby to switch the pulsator from one operational mode to the other.