Animal husbandry – Milkers – Methods of milking
Patent
1995-05-08
1997-09-16
Swiatek, Robert P.
Animal husbandry
Milkers
Methods of milking
119 1449, A01J 506
Patent
active
056669046
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to automatic milking apparatus and, in particular, but not exclusively, to hydraulic milking apparatus.
All hydraulic milking apparatus includes a cluster of four teat cups and a one-way valved clawpiece with the requirement that the various components should be constructed to avoid the introduction of air into the milk flow upstream of the one-way valves. In addition to the teat cups and the clawpiece mentioned above, other important components of the apparatus include a pulsator, four short milk tubes connecting the liner cores with the clawpiece, and a suction pump.
Each teat cup in the apparatus described above comprises a rigid outer casing containing a flexible liner which fits over one of the cow's teats. The annular space between the liner and the casing is called the pulsation chamber.
The suction pump acts via the valved clawpiece to apply a suction of typically 35 to 50 kPa to the liner cores when the clawpiece valves are open, the actual value in this range depending on the height of the milk jar or pipeline downstream of the clawpiece.
Apart from encouraging a flow of milk into the liner core and beyond, this suction is also effective to clamp the teat liner on to the teat (`adhesion`).
The pulsator is connected up to vary the vacuum in the annular pulsation chamber between a first longer-maintained value of 50 kPa (i.e. half atmospheric pressure) and a second shorter-maintained value of zero kPa (i.e. atmospheric pressure).
The pressure differential acting across the walls of the liner will vary in response to differences within the pulsation chamber and the liner core to produce a liner-closing phase, a liner-closed phase, a liner-opening phase, and, providing sufficient milk is available in the cycle, a "liner-open" phase in which the liner is fully open.
When the pulsation chamber approaches zero vacuum (atmospheric pressure) during the liner-closing phase, the liner core collapses on to the teat end and the compressive load on the teat end either alone, or in combination with the (small) vacuum level in the liner core, temporarily prevents the flow of milk through the teat duct.
During the liner closing phase, the collapse of the liners results in a relatively small vacuum in the liner cores (less than 5 kPa) which enables the one-way clawpiece valves to open in response to the greater vacuum being applied at their downstream sides by the suction pump. This allows an uninterrupted column of milk to flow rapidly from the liners to the clawpiece bowl and, optionally, beyond.
This column of milk has considerable kinetic energy and as it comes to rest (when the liner fully closes) it acts like a piston to pull a vacuum of up to 90 kPa in the liner core. At this point, the pressure differential across the clawpiece valves will have reduced sufficiently for the valves to close under their own weight. This will prevent any return of milk from the clawpiece bowl to the liner during the subsequent liner-opening phase of the milking cycle.
There comes a point in each liner-opening phase, however, when the increasing vacuum level in the pulsation chamber, the strain energy stored in the collapsed liner, and the increase in teat volume due to the build up of milk in the teat, all combine to overcome and relieve the compression load on the associated teat end. This, together with the flow-enhanced vacuum levels described above and now present in the liner core (up to 90 kPa), causes (i) milk to flow from the teat, (ii) the high vacuum within the liner to be relieved, and (iii) the liner to open.
It is to be noted that the clawpiece valves which are closes during the liner-opening phase, remain closed until the next liner-closing phase when, as above described, the relatively small core vacuums produced by the collapsing liners once again allow the clawpiece valves to open and milk to flow into the clawpiece bowl.
One of the advantages expected of all hydraulic milking systems is that the higher mean vacuum levels generated within the liner cores (as averaged over the dura
REFERENCES:
patent: 1388380 (1921-08-01), Schmitt
patent: 2687112 (1954-08-01), Shurts
patent: 3158136 (1964-11-01), George
patent: 3234906 (1966-02-01), Jensen
patent: 4803950 (1989-02-01), Griffin et al.
patent: 5161482 (1992-11-01), Griffin
British Technology Group Limited
Swiatek Robert P.
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