AU639049B2 - Pulsator improvements - Google Patents

Description

~-------~I--~3LIL11111~11111 I 1 U, ro Form COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-62 COMPLETE SPECIFICATION

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FOR OFFICE USE: Application Number: Lodged: Class Int. Class Complete Specification Lodged: Accepted: Published: Pi iority: Re!ated Art: Name of Applicant: TO BE COMPLETED BY APPLICANT ALFA-LAVAL (NZ) LIMITED Address of Applicant:307 Sandwich Road, Hamilton, New Zealand Actual Inventor: GRAHAM' JOHN HARKER Address for Service: Care of R.K. MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia, Australia Complete Specification for the invention entitled: "PULSATOR IMPROVEMENTS" The following statement is a full description of this invention, including the best method of perfor..ing it known toxucus I; _II_ ~X_ 1 -I i ii :j This invention relates to pulsators for milking plant.

The NU PULSE milking systems pulsator has been established in the market in New Zealand and overseas for some twenty years. The NU PULSE pulsator has a pulsation unit mounted on a milking claw.

A major development to the claw was made during the late 70's when the pulsator claw was modified by the inclusion of a diaphragm which separated the milk and air portions of the claw. Efficient operation of the MOC claw requires that air spaces within the claw be properly isolated.

Figure 1 of the accompanying drawings is a sectional illustration of a further modified MOC claw which comprises a claw bowl generally indicated by arrow 1 split about a flange 2 into upper and lower sections 3 and 4 respectively. The lower section 4 incorporates milk inlets 5 and a milk outlet 6. The upper section 3 incorporates a skirt 7 and a rim 8 which accommodates fixed and moving parts of the pulsator unit generally indicated by arrow 9. The main parts of the pulsator unit are a substantially funnel- shaped bobbin housing 10, a complimentary bobbin 11 a diaphragm. 12 and cap 13. The operation of the pulsator is described by New Zealand Patent Specification No. 189104, which description is incorporated herein by way of reference.

There are distinct air spaces within the pulsator these being space A defined by the cap 13 and diaphragm 12, space B within the interiors of the bobbin 11, 25 space C between tile bobbin 11 and bobbin housing 10, space D between the bobbin housing 10 and the rim 8, space E in the upper portion of the milking

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claw in space F in the lower portion of the milking claw which in the case of the MOC is separated by a diaphragm 14. Spaces C and D, B and E are communicable.

Whilst the MOC claw modification was introduced with the major objective of separating the :ir from the pulsation chamber of the milk claw from the milk in the claw. Vacuum equalisation during milking has been found to be an additional distinct advantage.

The MOC claw is generally tuned to give 50 to 55 pulsations per minute, however in practice the pulsation rate can speed up during milking as milk flow controls the pulsation rate which can get up to between 80 to 120 pulsations per minute depending on the cow. Movements of the diaphragm 14 (effecting pressures within the space E) assist to control pulsation rates.

Parts of the MOC claw are moulded in plastics with the outer body involved being a different plactic to the plastic from which the bobbin and bobbin housing 10 are moulded. The MOC claw is designed to be easily disassembled for cleaning and maintenance purposes and a number of rubber seals (as described, in New Zealand Patent Specification No. 189104) are provided to seal off air spaces of the claw. Properly maintained the seals provide satisfactory isolation between the various air spaces of the claw, however leakage has been o• found to occur in some pulsators between the bottom lip 15 of the bobbin housing 10 and its seat which includes the adjacent edge 16 of the upper 000o section 3 where to assist with seating of the bobbin housing matching surfaces 16 are chamfered. Leakage between these plastic to plastic surfaces can occur for one or a number of reasons. It is difficult to obtain an exact match of these

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*555 0* 0 surfaces because of the different characteristics of the plastics, manufacturing tolerances, and incorrect assembly. Some time ago thought was given to sealing this joint with a sealant or an o-ring. The use of sealants has the disadvantage that once the seal is broken the surfaces need to be recleaned and the sealant re-applied. O-rings are a problem because there is very little room from the provision of grooves for accepting an o-ring. These options were eliminated.

Because the surfaces 16 are chambered any variation between the angle of the chamfers which may occur as a result of a manufacturing fault, aging of the plastics or mis-alignment on assembly will create leakage and therefor a plain seal or ring is unlikely to give total insurance against leakage.

The NU PULSE pulsator is also sold in standard form without a diaphragm 14.

It is an object of the present invention to provide a bobbin housing for pulsators of the kind described which will provide satisfactory means of sealing the seating joint referred to. Further objects and advantages of the present invention will become apparent from the ensuing description.

According to the present invention therefore there is provided a bobbin housing for ulato f the kind dcibcd said bobbin housing being of a

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generally funnel-shaped configuration and having sealing means for providing and maintaining a substantially air tight seal between the bobbin housing and 4 -r seat g- gF housing and 4e- seat, said sealing means comprising a sealing ring of

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L~ir-- I; compressible material which is fixed to the base of the bobbin housing and which provides sealing contact between the bobbin housing and -i4t seat.

In the accompanying drawings: FiPures 2 and 2a: are partial side and sectional views of the base of the bobbin housing of the modified pulsator of Figure 1, and Figures 4 and 4a: are side and bottom views respectively of the bobbin for the modified pulsator of Figure 1.

-0 In accordance with the present invention the base 20 of the bobbin housing 11 is provided with a shoulder 21 to which sealing means generally indicated by arrow 22 is fitted. The sealing means illustrated is ring-shaped having an inner surface 23 and flat upper and lower surfaces 24. The outer peripheral 9.

15'0 surface 25 is fluted to enhance compressibility of the sealing means The sealing means 22 is also shown in Figure 1 and it will be appreciated from the s pulsator arrangement that the depth of the sealing means can be selected so that it is compressed when the cap 13 is secured. The shoulder 21 ensures that no upward displacement of the sealing means is possible. The sealing means is moulded or otherwise formed in a compressible material such as rubber, although other materials may be equally effective. 1 0

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Figures 4 and 4a of the drawings show the bobbin of the modified pulsator 11 in more detail. The bobbin 11 is funnel-shaped and complimentary to the bobbin housing 10 and a lower part 26 is provid ;d with three projecting ribs 27 which, when the pulsator is assembled ensure the bobbin 11 is correctly Scentred in the bobbin housing 10. The upper outer peripheral surfaces 28 of hur 0*

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the bobbin 11 are chamfered in order to minimise the width of surfaces 29 which have intermittent contact with the diaphragm 12.

Aspects of the present invention have been described by way of example and modifications and additions thereto may be made without departing from the spirit or scope of the invention as defined in the appended claims.

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Claims (8)

1. A bobbin housing for pulWators of the kind described, said bobbin housing being of a generally funnel-shaped configuration and having sealing means for providing and maintaining a substantially air tight seal between the bobbin housing and seat said sealing means comprising a sealing ring of compressible material which is fixed to the base of the bobbin housing and which provides sealing contact between the bobbin housing and -its seat.

2. A bobbin housing as claimed in claim 1 wherein the sealing ring is fitted to the base of the bobbin housing adjacent a shoulder which opposes displacement of the sealing ring.

3. A bobbin housing as claimed in claim 1 or claim 2 wherein the sealing S ring is provided with a circumferential flute enhancing its compressibility.

4. A pulsator having a bobbin housing as claimed in any one of claims 1 to S 3, and a bobbin complimentary with the bobbin housing, said bobbin o having a plurality of spacer members extending from lower portions thereof which ensure continuous axial alignment of the bobbin within the bobbin housing.

5. A pulsator as claimed in claim 4 wherein the upper outer surfaces of the bobbin are chamfered in order to minimise the width of surfaces in contact with a diaphragm above it. 1

6. A bobbin housing for a pulsator substantially as herein described with reference to the accompanying drawings.

7. A pulsator substantially as herein described with reference to the accompanying drawings.

8. A bobbin for a pulsator substantially as herein described with reference to the accompanying drawings. Dated this 14th day of March 1991. dl ALFA-LAVAL (NZ) LIMITED *'By its Patent Attorneys R K MADDERN ASSOCIATES 0 Sv *0S. 0:069: *00:0 0556 6~IA