AU2019355082B2

AU2019355082B2 - Aquaculture net cleaning system

Info

Publication number: AU2019355082B2
Application number: AU2019355082A
Authority: AU
Inventors: Peter B. Lindgren
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-10-04
Filing date: 2019-10-04
Publication date: 2025-05-15
Anticipated expiration: 2039-10-04
Also published as: CL2021000829A1; WO2020072936A1; AU2019355082A1

Abstract

An apparatus for cleaning nets underwater formed from a propeller housing with a centrally disposed axis with a plurality of blades (14) extending therefrom. An outer perimeter ring (18) secured to an outer tip of each blade (14) with a plurality of knuckles (20) secured to the outer perimeter ring (18). Each knuckle (20) including a curved surface (22) constructed and arranged to be forcefully presented to the aquaculture net upon rotation of said blades (14) for removal of growth by impact and shaking of the aquaculture net. An elastomeric hub (12) prevents spike loads.

Description

AQUACULTURE NET CLEANING SYSTEM FIELD OF THE INVENTION

This invention is related to the field of open

ocean aquaculture and, in particular, to aquaculture net

cleaning knuckles.

BACKGROUND OF THE INVENTION

Fish farming, often called aquaculture in

offshore ocean environments, is responsible for a large

part of fish supply for human consumption. Feed is the

largest cost of fish farming. Cleaning marine fouling from

or replacing nets to maintain good water flow and healthy

conditions is often the second largest cost of offshore

fish farming. During winter months cleaning may be

required only every 2 months. Durings summer months

cleaning may be needed every 10 to 15 days and growth can

easily get out of control risking proper water flow,

reduced disolved oxygen, slower growth and increased

mortalities.

Ocean fish farms are often placed in areas with

predators like sharks, sea lions and seals. Not all

locations have predator problems. In these areas a predator

net is commonly used to keep predators at a distance of at

least 1 to 2 meters away from grow out nets. The nets that

need to be cleaned are deployed vertically below the

floating rim with weighs attached at the lowest vertical

point of the net, and a bottom net attached horizontally

to the vertically net

In some applications the predator nets are

weighted to oppose water currents and predator attacks.

For instance, seals and sea lions will swim into predator nets and push the net to the grow out net and bite a fish if the predator net is not tight enough or if the animal is powerful enough.

Predator nets usually have a mesh of about 3 to 4

inch square holes sufficient to prevent predators from

entering the fish farm. Grow out nets have much smaller

mesh and may have square or hexagonal openings of 4- to 1 -"

across. When net systems are weighted the strands of the

predator nets are much higher due to the fewer strands to

support the weight and commonly have larger weights to

repel the animals. The present invention will clean both

grow out nets and predator nets, but predator nets can have

the additional problems of structures including hard

floats, frames, anchor chains, net weights and hard debris.

Fish grow out nets must be kept clean to assure

new water flow to maintain sufficient dissolved oxygen

content for fish growth and health. In the past nets were

treated with poison antimicrobials to reduce fouling

growth. The antifouling use is not allowed on most fish

farms today more than doubling the frequency of net

cleaning. Today increased net maintenance demands are

required due to eliminating the use of antifouling

chemical, increased concerns from disease, sea lice

parasites and higher seal and sea lion density. Increased

farm densities amplify the problems and every effort is

being made to improve net design and provide maintenance of

nets.

Lindgren WO 2016/183274A1 discloses a net

cleaning system designed to clean grow out nets including

elastomeric fingers and knuckles turning on the perimeter

of propellers. The system works well on grow out nets

including knuckles where the net weight is supported by more strands. For predator nets with larger mesh higher strand tension requires higher cleaning energy and spike loading from tighter nets, and impact on cage structures is not acceptable for net life or the equipment and special designs are required. The increased loads also reduce the speed of the equipment and therefore slower cleaning.

Elimination of Spike loads allows for more aggressive

cleaning while protecting the net and equipment.

Peak loads can be reduced in the current

invention in two ways. With knuckle designs that are

suitable for the nets and tension applied. And with the

use of specialty designed flexible drive coupling. The

spike rotational loads are designed using urethane rubber

or other elastomeric couplings between the first driven

hub. The current requirement needs a coupling to take both

rotational and perpendicular spikes in a small envelope of

the propeller mounting hub. Ideally the elastomeric hub is

designed to absorb rotational impact as well as allow

movement perpendicular to the net or obstruction. The hub

has special requirements because of the applied torque of

50 to 100 ft. lbs. applied and peak loads from impact many

times larger, and the small envelope available for

placement. Also required is the ability to remove the hub

from the propeller to replace it without requiring a new

and costly propeller. Obstructions can be anchor chains,

parts of the floating frame of the cage or weighting at the

lower edge of the net. Suitable elastomers from 70 to 85 A

shore have been tested successfully with inner diameter of

inches and outer diameter of 5.5 inches and flexible

element thickness of .1 at the O.D. to 1 1/4 inch at the

I.D.. Also unique in the flexible hub is the concave

surface in the flexible element configured to allow additional flexibility parallel to the axis when the propeller hits obstructions. Central to the flex element is a concave radius of .312 inches formed at a 4.25 inch diameter from each side providing flexibility parallel to the axis. The torque suitability and perpendicular flex is also affected by the choice of hardness or durometer and adjustment of the dimensions described.

Many flexible couplings have been designed in the

past. One common use is propellers with rubber hubs for use

with boat propulsion such as outboard motors and stern

drives. Such couplings are not field replaceable and are

made to slip on impact with limited movement that is

parallel to a drive shaft. Also are couplings made by Lov

Joy and others for engine and motor drives suitable for

rotational loads and small misalignment. None of them are

designed for repeated angular displacement of 15 degrees or

more, fit in small envelope and designed for easy

maintenance and severe overloads. Many have splined shafts

to slip or disengage parallel to the shaft while providing

torque and thrust.

Known prior art net cleaners include Patent

US3,628,489; US4,084,535; US4,252,081; US4,493,125;

US4,838,193; US4,970,747; US6,070547; US8,635,730; JP08

228614; JP409009818A; JP409044238A; JP410035587A.

It is desired to address or alleviate one or more

disadvantages or limitations of the prior art, or to at

least provide a useful alternative.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention

comprise an aquaculture net cleaning system comprising; at

least one propeller housing with a centrally disposed elastomeric hub with a plurality of blades extending therefrom; an outer perimeter ring secured to an outer tip of each said blade; a plurality of triangular shaped rigid knuckles having a forward surface and a trailing surface forming two opposed convex edges and a base secured to said outer perimeter ring, wherein each said forward surface constructed and arranged to be forcefully presented to an aquaculture net upon rotation of said blades; wherein rotation of said blades provides thrust for positioning said knuckles against the aquaculture net positioned underwater whereby said knuckles remove fouling from the aquaculture net by causing the aquaculture net to ride up said forward surface of said knuckle and down said trailing surface of said knuckle and upon the aquaculture net traversing said knuckle the aquaculture net returns to position allowing for removal of growth by impact and shaking the aquaculture net. The cleaning head is positioned against the surface of an underwater net wherein the cleaning features are constructed and arranged to remove soft and hard growth from the nets. The knuckles have angles measured from tangent to a curved surface and a line perpendicular to its base with changes from above 20 degrees to over 45 degrees. The curved surface approximates a radius of over 2 inches and less than 7 inches.

The disclosure may provide cleaning knuckles

having an improved efficiency and rotational speeds for

better cleaning of a net.

The disclosre may provide improved knuckles that

allows for the development of smaller lighter systems with

improved cleaning.

The disclosre may teach a knuckle curved surface that can be calculated by a cosine angle parallel to a net

face and a sine angle perpendicular to the net face.

The disclosre may provide a net cleaning device

that includes options to maximize performace based on net

mesh size and the type of fouling.

The disclosre may provide an aquaculture net

cleaning system wherein knuckles are not symmetrical.

The disclosre may provide flexible and changeable

coupling that will reduce spike loads in both the

rotational and paralled to the axis direction extending the

life of equipment allowing lighter more efficient

operation.

Advantages and benefits associated with this

invention will be apparent to those skilled in the art from

the description, examples and claims which follow. In

combination the articulated knuckle designs with the

elastomeric coupling may open the design window for

improved cleaning with less power and wear on the net and

equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention

are hereinafter described, by way of example only, with

reference to the accompanying drawings in which:

Figure 1 is a perspective view of the aquaculture

net cleaning system propeller housing with knuckles secure

to a perimeter ring;

Figure 2 is an enlarged view of a portion of

Figure 1;

Figure 3 is a front plane view of a first

embodiment knuckle;

Figure 4 is a perspective view of Figure 3;

Figure 5 is a front plane view of a second

embodiment knuckle;

Figure 6 is a perspective view of Figure 5;

Figure 7 is a front plane view of a third

embodiment knuckle;

Figure 8 is a perspective view of Figure 7;

Figure 9 is a front plane view of a fourth

embodiment knuckle;

Figure 10 is a perspective view of Figure 9;

Figure 11 is an end view of Figure 9;

Figure 12 is a front plane view of a fifth

embodiment;

Figure 13 is perspective view of 12;

Figure 14 is exploded view of the elastomeric

hub; and

Figure 15 is a cut away view of the elastomeric

hub.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A detailed embodiment of the instant invention is

disclosed herein, however, it is to be understood that the

disclosed embodiments are merely exemplary of the

invention, which may be embodied in various forms.

Therefore, specific functional and structural details

disclosed herein are not to be interpreted as limiting, but

merely as a basis for the claims and as a representation

basis for teaching one skilled in the art to variously

employ the present invention in virtually any appropriately

detailed structure.

Figure 1 and 2 depict an aquaculture net cleaning

system technology comprising a propeller housing with a centrally disposed elastomeric hub 12 with a plurality of blades 14 extending from the elastomeric hub 12 to an outer tip 16 of each blade. An outer perimeter ring 18 is secured to the outer tip 16 of each blade 14. A knuckle 20 is secured to the outer perimeter ring 18. Each knuckle 20 includes a curved surface 22 constructed and arranged to be forcefully presented to the aquaculture net upon rotation of the blade 14 for removal of growth by impact and shaking of the aquaculture net.

Lower tensioned net loads with the described

technology is analogous to a base guitar where strings move

easily and far when compared to standard guitar or banjo

where movement is very low with the same force and movement

is far less. The knuckle design of the instant invention is

designed to play the standard guitar versus the base

guitar. The cleaning of nets with the new knuckle design

results from impacting hard growth by cleaning knuckles,

friction on net twine and aggressive shaking of the net to

remove soft growth. The energy required to do this without

net damage is a function of the net or twine tension and

the angle of the moving knuckle, the speed and the distance

pushed.

The Lindgren disclosure WO 2016/183274 Al works

well with low tension nets. However, with high tension

large mesh nets the net is much more difficult to shake and

move distant from normal positions. The forces are a

geometric function being the sine or cosine of the angle of

the knuckle to compare the forces paralleled to the face of

the net versus perpendicular to the face of the net. To

reduce the force on the net and torque requirement of the

equipment and clean well requires a curved surface to change the angle as the net is moved to keep the forces more constant than can be achieved with a straight surface.

Figures 3 and 4 depict a preferred knuckle 20

having a curved surface 22 on a leading edge and compound

angle trailing edge 24. Apertures 26 and 28 allow for

receipt of fasteners 30 and 32. The centerline 34 is

illustrated as about .375" from the center of the apertures

26, 28. The knuckle 20 is more net friendly, reduces power

requirement and improves equipment life. This knuckle 40

embodiment having a length of about 2.086". The design is

symmetrical to operate in clockwise or counterclockwise

direction and can be reversed if worn.

Figures 5 and 6 depict a knuckle 40 having a

symmetrical edge surfaces 42, 44 with a centerline 46

illustrated as about .375" from the center of the apertures

48, 50. This knuckle 40 embodiment having a length of

about 1.802". Figures 7 and 8 depict a knuckle 60 having

non symmetrical edge surfaces 62 and 64. Edge surface 62

having an angle of about 25 degrees, rear edge surface 64

having a compound angle slightly more than 65 degrees.

Figures 9-11 depict a knuckle 70 having symmetrical edge

surfaces 72, 74 of about 60 degrees. The length is about

2.0" and the curvature of the knuckle provides a radius of

about 9.75. Excluding friction the forces on the net.

Figures 12 and 13 depict a knuckle 80 with a rapidly

sloping curved edge 82 and rearward curved edge 84. This

embodiment provides faster net strand return that can

improve cleaning on very tight nets at the expense of an

efficient reverse that is can be used to move more easily

or untangle kelp, ropes and other fouling.

Forces from the cleaning knuckle can be compared

by calculating as follows:

Parallel to net face = force (cosine angle) Perpendicular to net face = force (sine angle)

Table 1

Angle from centerline Cosine Sine

22 degrees .927 .374

30 degrees .866 .5 65 degrees .406 .906

Maximum torque for a propeller in this type of

net cleaner is 50 to 100 ft. lbs. with approximately 30% of

the power delivered to the propeller blades 70 lbs. force

is remaining for typically 8 cleaning knuckles or 8.75 lbs.

per knuckle. Single angle knuckles typically have an angle

of around 30 degrees from centerline.

Table 2

Single Force Force

angle parallel perpendicular

30 degrees to net to net

Curved angle 4" radius 7.6 4.4

Lower curve 22 deg. 8.1 3.3

Upper curve 65 deg. 3.6 8.4

Shown in Table 2 is how dramatically the forces

parallel and perpendicular the net change as the knuckle

moves on the net strand. The curved angle knuckle can

provide high forces to move the aquaculture net parallel to

the net face and then shift to high push perpendicular to

the net for maximum movement with less torque. This is not

possible with a single angle.

The existing designs were symmetrical commonly

with an acute angle to centerline of approxinlately 30

degrees. Because of the low angle on the downstream side

recovery of the twine is fast and also shakes off fouling.

With the advance invention of the curved knuckle the

downstream side can have inhibited return recovery at low

rotational speeds causing less cleaning power of the twine

not quickly returning to position rapidly. The solution is

a more acute or straight angle on the downstream side.

Sometimes the propellers are run in reverse to untangle or

reposition the cleaning head. The downstream angle must not

be so acute to prevent reverse rotation of above below 20

degrees. When in reverse the propellers quickly move the

cleaning head off the net and only a small angle is

required. The current invention increases efficiency and

rotational speeds for better cleaning.

Referring to Figure 14, illustrated is an

exploded view of the elastomeric hub 12 which forms a

flexible drive coupling to facilitate the use of the

knuckles. The elastomeric hub operates as a shock absorber

to lessen impact damage to the knuckles when removing aged

barnacles or other hard growth that would otherwise case

spike loads. The elastomeric hub 12 consists of a driver

84 having a plurality of splined shaped formations 86, 88

positioned around the diameter of the driver 84 on each

side of a centrally disposed guide wall 90. In the

preferred embodiment, the driver 84 is formed from a rigid

material such as aluminum, delrin or the like. A

elastomeric body 92 is over molded to the driver 84 wherein

the splined shaped formations 86, 88 maintain the

elastomeric body 92 from rotating separately from the

driver 84. Similarly, the guide wall 90 which extends

outwardly from the splined formations 86, 88 prevents the

elastomeric body 92 from detaching from the driver 84. In

the preferred embodiment the elastomeric body 92 is a

urethane elastomer. While the inner surface 94 of the elastomeric body 92 is molded to the splined formations 86,

88, and outer surface 96 has a plurality of concave

sections formed from valleys 98 and peaks 99 along the

outer surface 92. The elastomeric hub 92 is constructed

and arranged to prevent spike loads in a rotational

direction and parallel to the rotational axis of the

propeller simultaneously. The elastomeric body 92 forms a

flexible element preferably with a durometer between 70 and

90 A shore hardness, the I.D. and O.D. of the flexible

element and mating surface are splined. A base 100 of the

hub 12 has an inner surface 104 having concave sockets 106

for receipt of the valleys 98 and peaks 99 of the

elastomeric body 92. The outer shell preferably

constructed from aluminum for support of the blades 14 and

outer perimeter ring 18. A coupling ring 108 secures the

driver 84 within the base 100, the coupling ring 108 may be

secured along a groove 110 formed along an edge of the base

100. A protective shield 112 is securable to the base 100

having a lip 114 for securement along edge 116 of the base.

All patents and publications mentioned in this

specification are indicative of the levels of those skilled

in the art to which the invention pertains. It is to be

understood that while a certain form of the invention is

illustrated, it is not to be limited to the specific form

or arrangement herein described and shown. It will be

apparent to those skilled in the art that various changes

may be made without departing from the scope of the

invention and the invention is not to be considered limited

to what is shown and described in the specification and any

drawings/figures included herein.

The term "coupled" is defined as connected,

although not necessarily directly, and not necessarily mechanically. The use of the word "a" or "an" when used in conjunction with the term "comprising" in the claims and/or the specification may mean "one," but it is also consistent with the meaning of "one or more" or "at least one." The term "about" means, in general, the stated value plus or minus 5%. The use of the term "or" in the claims is used to mean "and/or" unless explicitly indicated to refer to alternatives only or the alternative are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and "and/or."

The terms "comprise" (and any form of comprise, such as "comprises" and "comprising"), "have" (and any form

of have, such as "has" and "having"), "include" (and any

form of include, such as "includes" and "including") and

"contain" (and any form of contain, such as "contains" and "containing") are open-ended linking verbs. As a result, a

method or device that "comprises," "has," "includes" or "contains" one or more steps or elements, possesses those

one or more steps or elements, but is not limited to

possessing only those one or more elements.

One skilled in the art will readily appreciate

that the present invention is well adapted to obtain the

ends and advantages mentioned, as well as those inherent

therein. The embodiments, methods, procedures and

techniques described herein are presently representative of

the preferred embodiments, are intended to be exemplary and

are not intended as limitations on the scope. Changes

therein and other uses will occur to those skilled in the

art which are encompassed within the spirit of the

invention and are defined by the scope of the appended

claims. Although the invention has been described in

connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.

Throughout this specification and the claims

which follow, unless the context requires otherwise, the

word "comprise", and variations such as "comprises" or

"comprising", will be understood to imply the inclusion of

a stated integer or step or group of integers or steps but

not the exclusion of any other integer or step or group of

integers or steps.

The reference in this specification to any prior

publication (or information derived from it), or to any

matter which is known, is not, and should not be taken as,

an acknowledgement or admission or any form of suggestion

that that prior publication (or information derived from

it) or known matter forms part of the common general

knowledge in the field of endeavour to which this

specification relates.

Claims

CLAIMS The claims defining the invention are as follows:

1. An aquaculture net cleaning system comprising:

at least one propeller housing with a centrally

disposed elastomeric hub with a plurality of blades

extending therefrom;

an outer perimeter ring secured to an outer tip of

each said blade; and

a plurality of triangular shaped rigid knuckles having

a forward surface and a trailing surface forming two

opposed convex edges and a base secured to said outer

perimeter ring, wherein each said forward surface

constructed and arranged to be forcefully presented to an

aquaculture net upon rotation of said blades;

wherein rotation of said blades provides thrust for

positioning said knuckles against the aquaculture net

positioned underwater whereby said knuckles remove fouling

from the aquaculture net by causing the aquaculture net to

ride up said forward surface of said knuckle and down said

trailing surface of said knuckle and upon the aquaculture

net traversing said knuckle the aquaculture net returns to

position allowing for removal of growth by impact and

shaking the aquaculture net.

2. The aquaculture net cleaning system according to Claim

1, wherein angles measured from tangent to said forward

surface from said base of said knuckle changes from 20

degrees to over 45 degrees.

3. The aquaculture net cleaning system according to either

of Claim 1 or 2, wherein said forward surface approximates

a radius of over 2 inches.

4. The aquaculture net cleaning system according to Claim

1, wherein said forward surface of said knuckle is about 30

degrees from a centerline of said base wherein about 30% of

the power to said propeller system is directed to said

blades and about 70% to said knuckles.

5. The aquaculture net cleaning system according to claim

1, wherein said forward surface of the knuckle is over 66

degrees measured from perpendicular to the propeller rim

and tangent to said forward surface.

6. The aquaculture net cleaning system according to claim

5, wherein said forward surface is unsymmetrical and said

trailing surface is relieved to allow faster net recovery.

7. The aquaculture net cleaning system according to Claim

1, wherein said forward surface has about a 22 degree angle

from a centerline of said base with a .927 cosine angle and

a .374 sine angle, said forward surface is calculated by a

cosine angle parallel to a net and a sine angle

perpendicular to the net.

8. The aquaculture net cleaning system according to Claim

1, wherein said forward surface has about a 30 degree angle

from a centerline of said base with a .866 cosine angle and

a .5 sine angle of said forward surface is calculated by a

cosine angle parallel to a net and a sine angle

perpendicular to the net.

9. The aquaculture net cleaning system according to Claim

1, wherein said forward surface has about a 65 degree angle

from a centerline with a .406 cosine angle and a .906 sine

angle of said forward surface is calculated by a cosine

angle parallel to a net and a sine angle perpendicular to

the net.

10. The aquaculture net cleaning system according to Claim

1, wherein said forward surface is constructed and arranged

to apply about 7.6 lbs. of force parallel to the

aquaculture net and about 4.4 lbs. of force perpendicular

to the aquaculture net.

11. The aquaculture net cleaning system according to any

one of Claims 1 to 10, wherein said knuckles are not

symmetrical.

12. The aquaculture net cleaning system according to any

one of Claims 1 to 11, wherein said knuckles have a length

of less than 2 inches and are removably fastened to said

perimeter ring.

Fig.,2

Fig. 4

49,05°

18,73°

R3.0

22

2.086 20

24 34

26 28

375 Fig. 3

Fig. 6 56.58

21,92°

R2.5 44 42

1.802 46

40

48 50

.375

Fig. 5

R2.500

65,09°

21,92° 62

25,00° 64

60

0

Fig. 7

Fig. 8

Fig. 10

89,750

70 72 2.000

Fig. 11 Fig. 9

60