GB2159685A - Automatic milking apparatus - Google Patents

Description

1

SPECIFICATION

Automatic milking apparatus The present invention relates to automatic milking 70 apparatus.

The basic components of a milking installation, at least as far as the present invention is concerned, are (1) a cluster of fourteat cups including (2) a clawpiece, (3) a suction pump and (4) a pulsator.

Each teat cup comprises a rigid outer casing containing a flexible linerwhich fits over one of the cow's teats. A pressure of approximately 50 kPa below atmosphere is continuously applied to the "core" space enclosed bythe liner. Apartfrom encouraging a 80 flow of milk into the core space, this negative pressure is also effectiveto clamptheteat lineron totheteat this is referred to as "adhesion".

The pressure applied to the annular space between the liner and the rigid casing alternates, however, between 50 kPa below atmosphere and atmosphere thanksto the action of the pulsator. Atthe first of these values, there is zero pressure differential across the liner and milk is sucked from the teat into the core space. This milk passes down a flexible "short milk" tube into one of the fourtubular inlet "nipples" projecting upwardlyfrom the interiorvolume of a special junction unit called a "clawpiece". From there the milk is drawn down through an outlet nipple and via a "long milk" tubeto an appropriate receptacle or pipeline. The otherthree nipples of the clawpiece are connected to similarteat cups and thence to the other teats of the cow's udder.

It will be appreciated that in operation of the cluster, the passage of milk from the teats is intermittent. Thus 100 in a complete pulsation cycle, asthe pulsation chamber is re-evacuated from the completelycollapsed condition, say,the liner in contactwith theteat widens andthe size of theteatsinus increases.

Simultaneouslythe liner beginsto open beneath the teat and,when sufficiently open, milkstartsto flow through the streakcanal. Continued expansion of the streakcanal and opening of the linerfollows until the liner isfully open. Milk beginsflowing from theteat when the liner is about half open and continues until the liner is about half closed. The teat sinus has already become somewhat smaller bythis time and the region of the compressed streak canal appears elongated due to complete collapse of the liner on the teat. As the liner closes, milkflow ceases before complete collapse beneath the teat, indicating clearly that cessation of milkflow is not caused bythe liner cutting off the vacuum to the end of the teat but by the force exerted bythe closing liner itself. The cycle then repeats, the nextflow of milk beginning when the liner is again about half open.

Clearly in any such system, there must be some mechanism for partially releasing the vacuum within thefully collapsed liner in orderthat it can return towards its partially and laterfully open state. Otherwise, the liner, once collapsed will remain so throughoutthe subsequent pulsation cycles.

Where the design of clawpiece is such that itwill allow milkflow in both directions through the clawpiece,the linervacuum can be released if desired 130 GB 2 159 685 A 1 by allowing some of the milkto flow back upthe short milktubes intothe linercore. It is normally preferred, howevento allow airto enterthe linercore atthis stage andforthis and other reasons an appropriate air bleed is invariably provided somewhere in the cluster.

Where a so-called---one-way-clawpiece is used, i.e. one allowing a downward flow of miikfrom the cows udder but not inthe reverse direction, then it has been accepted that an air bleed must be present in the short milktube to allow a re-expansion of the liner as above described.

The present application discloses an invention which cuts across all the accepted thinking on this subject in so far as it provides a method of automatic milking comprising the step of drawing the milk from the teat past one or more non-return valves without the introduction of air into the milkflow upstream of the valve or valves. Expressed in terms of apparatus, the present invention provides an automatic milking apparatus having one or more one-way clawpieces and pneumatically- isolated teat liners i.e. teat liners effectively sealed during milking from any supply of airto the milk-carrying core regions of the teat liners.

Atthis stage, it is not understood how the teat liners of the new apparatus are able to expand from their fully collapsed state withoutthe introduction of air or miikfrom a source down-stream of the liners. It seems clearthatthe vacuum cannot be initially released by milkflowing from the teats because this milkflow only commences when the liner is already half open again.

Reverting fora moment to the prior art, it should be pointed outthat apparatus has already been disclosed in GB 394983 and GB 1451995 in which the milk line from the teat includes a one-way valve and no air-bleed upstream of the valve. As the mechanism by which the method of the present invention functions is not understood, it is impossible to say whether the appliances illustrated in these documents could be operated in a similarfashion to those of the present invention orwhetherthey would fail to operate at all. Clearly, until the advent of the present invention, the appliances as illustrated would have been dismissed out of hand as unworkable on the basis thatthey fail to provide any means whereby the teat liner could expand once milkflowfrom the teat had ceased during the milking cycle.

Returning nowto the present invention, British Patent 2057845B (National Research Development Corporation) envisages two types of one-way clawpiece, one with an air admission hole in the clawpiece upstream of the clawpiece valves and one in which this hole is absent and the air bleed is provided in some other part of the milking apparatus of which the clawpiece forms a part. This lattertype would be an eminently suitable one-way clawpiece for use in the automatic milking apparatus of the present invention.

It is a potential drawback of the particular design of oneway clawpiece referred to above,thatwhen milking has been completed, a small quantity of milk will remain trapped in the short milktubes and in the clawpiece chamber. This may result in spillage when the milking cluster is removed from the cow after milking.

In an attemptto alleviatethis situation, a modified version of the clawpiece is now proposed comprising 2 GB 2 159 685 A 2 control means which are effective when called into operation to allow airto enter the clawpiece upstream of the clawpiece valves. When this happens, the resulting change in pressure differential acrossthe clawpiece valves will allowthe partial vacuum present 70 in the clawpiece chamber during milking to hold the valves awayfrom their seats while the trapped milk flows pastthe valves and out through the long milk tube. Escape through the now open valve ports is substantially presented by the incoming stream of air which will persist until the vacuum in the clawpiece chamber is no longer sufficient to hold the valves open and gravity returns them to their valve-closed positions. Besides reducing the likelihood of spillage as above described, operation of the control means will also facilitate cluster removal by reducing the amount of suction present in theteat cup liners.

Convenientlythe control means is arranged to be operated manually as and when desired or it may be operated as part of an automatic cluster removal operation eg by having the control means provide the attachment partforthe removal apparatus.

Although itwill normally be requiredthatthe control means should return to its inoperative position on release, a currently preferred design of clawpiece allows the control means to be locked in its operative position forcleaning purposes using conventional cleaning techniques e.g. circulation cleaning oracidified boiling water cleaning.

If the possibility and backflushing is required for rinsing the milking cluster between use on one cow and the next, then guide means are preferably provided within the clawpiece chamberto allow the valves to be displaced by relatively large amounts from their seats on inversion of the clawpiece, say, while guiding them backto theirvalve-closed positions on return of the clawpiece to its usual upright position.

According to another aspect of the present inven- tion, an automatic milking apparatus has one or more non-return valves, pneumatically-isolated teat liners as hereinbefore defined, and control means which are effective when called into operation to a] low airto enterthe apparatus upstream of the non-retu m valves.

It would be expected thatthe present invention would have advantages over a milking system using otherthan one-way clawpieces since it avoids the flow back of milk with all its undesirable consequences both as regards milking efficiency and transfer of disease. However present indications are that the combination of one or more one-way clawpieces with an absence of air bleed also resu Its in significant operational advantages over previous air-bled sys- tems using one-way clawpieces. Briefly these are (i) a shorter overall milking time allowing a corresponding reduction in the size of the milking installation; (ii) less damage to them ilk (less fatty acids released due to lesser agitation of milk); and (iii)---foaming-is reduced making it easierto meter and measure the milk. There is also strong evidence to show that (iv) the new clusterwill lear, to increased milk yield -at least for animals not accustomed to a conventional system.

The shorter milking time listed in (i) above is thought to result principal ly from the faster peak flow rate produced and from the shorter low flow period occurring at the end of the milking process. With prior air-bled systems, there is loss of adhesion at the end of milking and the teat cup rides up making the liner less effective and leading to a prolonged "dribble" period. With the better adhesion resulting from the present invention, ride-up is less likely to occur and the dribble period is significantly reduced. As compared with a conventional cluster,the milking time might be reduced by one minute, say, from the usual value of 5 or6 minutes. This 20% orso reduction in milking time should allow a corresponding reduction in the amount of equipment required in the milking parlour.

Regarding point (5) above, the damage referred to, technically known as "lipolysis", is produced bytoo fierce agitation of the milkwhich shears the fat globules in the milk and frees the fatty acids producing a bittertaste. Because of the dynamics of milk transport, lipolysis is particularly evident in milking parioursystems in which the milk is piped direct through -high lines" (i. e. abovethe level of cows) to a bulktankfrom whence itcan be emptied bythe tanker. The apparatus of the present invention provides a much gentler system in which excessive agitation is forthe most part avoided altogether.

Turning nowto point (iii), it is envisaged thatthe amount of foam can befurther reduced if milk is fed intothe bottom of the recorderjars.

Lastly, as regards point (iv),the currenttrials show thatthe increase in miikyield, or more exactly, lactation yield, can be increased by 5% or more, especiallyfor newly calved animals.

Aswell asthe advantages listed above, others may become apparent in time. For example, the ability of the apparatus of the present invention to provide a substantially air- free milkflow should allow more efficient dynamic metering of the milkflow since errors arising from the usual air content in the flowwill be avoided.

Throughoutthe specification, the term "cows" should not be narrowly interpreted but should be taken to include heifers and newly calved animals.

Byway of example only, referencewill now be made to the accompanying drawings in which Figure 1 shows a simplified and somewhat diagrammatic view of part of a typical milking installation according to the present invention and Figures 2 and 3 are a plan and part-sectional exploded view of a particular design of clawpiece for use in the installation of Figure 1.

Forconvenience, Figure 1 of the drawing only shows two milking units 8 although in practice there will typically beten or so such units in an averagesized milking installation.

Each unit8 consists basically of fourteat cups 10, a one-way clawpiece 14 e.g. of thetype previously described as being suitable in the introductory portions of the specification, fourshort milktubes 12 connecting the teat cups to the clawpiece, and a long milktube 16 taking the milkfrom the clawpiece to a recorderjar 18 (orother milk-measuring device).

The bottoms of the recorderjars are connected to a common milk conveyance pipeline 20. In an alternative embodiment (not shown), thejars 18 (or equivalent) are omitted and the long milktubes 16 lead directly to the common milk conveyance pipeline 20.

3 Reference numeral 22 indicates the milking vacuum pipeline while the reference numberal 24 indicates the airline forthe pulsator 26.

As shown, the common milk conveyance pipeline 20 leads to a receiver vessel 28 and in operation of the installation, a milk pump 30 operates to draw milk into the vessel 28 for discharge, via pipeline 32, to a bulk tank(notshown).

The installation is completed by the usual sanitary trap 34, vacuum regulator 36, interceptor 38 and vacuum pump 40.

Although particular designs of one-way clawpiece have been referred to above, it is envisaged that other designs of one-way clawpiece may also prove satis- factory. However, it is to be u nderstood that whatever type of one-way clawpiece is chosen, it is important that there is no air-bleed present in the clawpiece when it is in use which could destroy the overall requirementthat a pneumatically-isolated passage- way should be present forthe flow of milk th rough the apparatus.

Referring nowto Figures 2 and 3, these show a modified form of one-way ball-valve clawpiece 46 in which a control means 48 is provided for the introduction of air below each of the bal I valves 50 as and when required for the purposes discussed in the introductory portions of the application.

In essence, the control means 48 comprises four upwardly-tapering rubber conical closure members 52 urged upwardly bythe different arms of a cruciform spring steel member 56to seal off the lower ends of narrow passageways 58 in the body 60 of the clawpiece. Attheir upper ends, the passageways 58 open out into the valve seats 62.

The centre part of member 56 is rigidly secured to a central rod 64 passing through a tubu lar section 66,67 which is provided in two parts formed integrally with the top and bottom parts of the clawpiece 46. The bore of section 66,67 is pneumatically and hydraulically isolated from the interiorvolume of the clawpiece, a washer 69 guaranteeing thatthere is no leakage where the two sections 66,67 join.

Upward axial displacement of the rod 64 is effected either manually by a knob 71 secured to the lower end of the rod, or by a rotational ly free attachment part 73 used for automatic cluster removal atthe top end of the rod, or by a rotary cam device 75 also atthe top of the rod and designed to operate as will hereinafter be described. Whichever system is used in any particular instance, an upward motion of the rod from the valve-closed position illustrated in Figure 3 will cause the arms of member 56 to bend in a pivotal motion about an appropriate one of four downwardly-tapering ribs 77 secured to the underside of the clawpiece body as shown. This in turn will causethe closure members 52to be displaced downwardlyto allow ambientairto pass upthe passageways 58to the underside of the ball valves 50 with the results already described earlier inthe application.

Returning nowtothe cam device 75 referred to above,this comprises a knurled ring 79 having an internally-stepped central recession 80 adapted to accommodate a cross-pin 81 of the rod 64. The upper surface of this step portion comprisesfour pin- retaining raised sections 82 recessed attheir upper GB 2 159 685 A 3 endsto acceptthe pin and separated byfour pin-retaining trough sections 83. Accordingly, rotation of the knob 79will engagethe pin eitherwith a raised section 82to open the closure members 52 orwith a trough section 83 if the closure members areto be closed. If clesired,the raised sections are alternately high and lowso asto allowtwo degrees of opening of the closure members 52 if this isthought desirable.

Reference numeral 84 indicates guide elementsfor controlling the movement of ball valves 50 if the clawpiece isto be inverted for backflushing as already described and reference numerals 87 and 88 in Figure 1 respectively indicate a water supply and valve allowing this flow of water (with or without disinfec- tant and/or heat) to the inverted clawpiece. As will best beseenfrom Figure 2, the elements 84 are arranged in groups of three with the radially innermost element of each group provided with a ball-retaining lip 85.

Returning nowto Figure3,the remaining reference numberals 90 and 91 indicate the usual short milk tubes and long milk tubes respectively while reference numeral 93 indicates a conventional pulsation distribution blockfitted on top of the clawpiece in what has now becomethe usual way.

Claims (8)

1. A method of automatic milking comprising the step of drawing the milkfrom the teat past one or more non-retu rn valves without the introduction of air into the milkflow upstream of the valve orvalves.

2. An automatic milking apparatus having one or more one-way clawpieces and pneumatically-isolated teat liners as hereinbefore defined.

3. An apparatus as claimed in Claim 2 in which the clawpiece includes control means which are effective when called into operation to allow airto enterthe clawpiece upstream of the clawpiece valves.

4. An apparatus as claimed in Claim 3 in which the control means is arranged to be operated manually as and when desired or as apart of an automatic cluster removal operation.

5. An apparatus as claimed in Claim 3 orClaim 4 in which the control means is adapted to be locked in its operative position.

6. An apparatus as claimed in any preceding claim in which guide means are provided within the clawpiece chamberto allow the valves to be displaced by relatively large amounts from their seats on inversion of the clawpiece.

7. An automatic milking apparatus having one or more non-return valves, pneumatically isolated teat liners as hereinbefore defined, and control means which are effective when called into operation to allow airto enterthe apparatus upstream of the non- return valves.

8. A method or apparatus as claimed in any preceding claim and substantially as hereinbefore described with referenceto and/or as illustrated in the accompanying drawings.

Printed in the united Kingdom for Her Majesty's Stationery Office, 8818935. 12185, 18996. Published at the Patent office. 25 Southampton Buildings, London WC2A 1AV, from which copies may be obtained.