WO2016033678A1

WO2016033678A1 - Underwater surface cleaning and debris collection device

Info

Publication number: WO2016033678A1
Application number: PCT/CA2014/050839
Authority: WO
Inventors: Vincent M. CUMMINGS; Matthew R. BONE; Daniel W. MCINTYRE
Original assignee: Whale Shark Environmental Technologies Ltd
Current assignee: Whale Shark Environmental Technologies Ltd
Priority date: 2014-09-04
Filing date: 2014-09-04
Publication date: 2016-03-10
Anticipated expiration: 2017-03-04

Abstract

Apparatus for cleaning an underwater surface has a brush/shroud assembly for scrubbing fouling from the underwater surface. One or more brush/shroud assemblies can be supported on a brush cart with three degrees of freedom of movement relative to a frame of the brush cart. Debris released by cleaning is captured within the shroud and removed through an outlet by rotational flow forces created by the brush and an impeller rotating within the shroud. The outlet is coupled to a surface pump to transfer removed fluid and debris to a surface filtration unit.

Description

UNDERWATER SURFACE CLEANING AND DEBRIS COLLECTION DEVICE

Technical Field

[0001] Some embodiments of the present invention relate to apparatus and methods for cleaning surfaces located primarily underwater, for example the hulls of ships or other floating vessels.

Background

[0002] The cleaning of underwater surfaces, including the portion of vessel hulls that is normally underwater, is an important task. Shipping is a major means of distributing goods for sale globally. The growth of biological organisms and accumulation of debris on hulls of ships (fouling or bio-fouling) increases the drag experienced by a hull moving through water, reducing the hydrodynamic performance of a vessel and increasing the amount of fuel required to propel the vessel. The biological organisms can form biomass, i.e. a mass of biological growth, whether alive or dead, attached to the hull of a ship. Examples of biomass include shell growth (e.g. barnacles, tube worms, mussels or the like), seaweed grass, algae and/or algae slime.

Regular cleaning of the hull is important to remove biomass and maintain efficient performance of a vessel.

[0003] Many vessels, particularly larger vessels, cannot readily be removed from water in order to clean the hull of the vessel. Accordingly, much hull cleaning is carried out using underwater apparatus.

[0004] A disadvantage of using an underwater apparatus to clean underwater surfaces such as the hulls of vessels is that debris (i.e. the removed accumulated material from the underwater surface, which may include for example biomass and/or paint that is removed while cleaning) is removed from the underwater surface and distributed into the surrounding water. This can have a detrimental effect on water quality, and recent regulatory changes are aimed at preventing the release of such debris into the surrounding water of harbors and other areas where underwater cleaning may be carried out.

[0005] There remains a need for underwater cleaning apparatus and methods that can clean underwater surfaces such as vessel hulls without releasing a significant amount of debris into the surrounding waters. It is also desirable that the use of such underwater cleaning apparatus not cause damage to the underwater surface being cleaned, for example to avoid voiding any warranty that may cover the paint on the underwater surface.

[0006] The foregoing examples of the related art and limitations related thereto are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.

Summary

[0007] The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative, not limiting in scope. In various embodiments, one or more of the above-described problems have been reduced or eliminated, while other embodiments are directed to other improvements.

[0008] One aspect provides a brush/shroud assembly for cleaning an underwater surface. The brush/shroud assembly has a brush for loosening debris on the underwater surface, a shroud at least partially enclosing the brush to contain the debris, an impeller rotatably mounted within the shroud, and an effluent outlet for removing debris from the shroud. Rotation of the impeller provides a force to drive fluid and debris through the effluent outlet. The shroud can have a generally circular outer diameter. The effluent outlet can be provided on an outer circumference of the shroud. The shroud can have an inwardly angled peripheral portion extending between the outer circumference of the shroud and a distal portion of the shroud.

[0009] One aspect provides a brush cart for cleaning an underwater surface. The brush cart has a frame, a plurality of surface-contact points coupled to the frame for contacting the underwater surface, a brush chassis coupled to the frame, and at least one brush/shroud assembly extending from the brush chassis towards the surface contact points. The brush/shroud assembly has a rotatable brush having bristles oriented generally towards the surface contact points, a rotatable impeller, a drive motor for driving the brush and/or the impeller, and a shroud enclosing the brush and the impeller to define a cavity for containing debris released as the underwater surface is cleaned. The brush/shroud assembly can be joined to the frame with three degrees of freedom relative to the frame. The position of the brush/shroud assembly relative to the frame in the distal and proximal directions can be adjustable. The three degrees of freedom can be provided by a hinge region on an arm of the frame together with a universal swivel joint coupling the brush/shroud assembly to the arm.

[0010] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions.

Brief Description of the Drawings

[0011] Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

[0012] Figure 1 shows a schematic view of an example embodiment of an underwater surface cleaning system.

[0013] Figure 2 shows a perspective view of a portion of an example embodiment of a brush cart assembly.

[0014] Figure 3 shows an exploded view of an example embodiment of a brush/shroud assembly.

[0015] Figure 4 is a cross-sectional view of an example embodiment of a brush/shroud assembly.

[0016] Figure 5 shows a perspective view of an example embodiment of a brush chassis.

[0017] Figure 6 is a partial view showing a hinge region of an arm of a brush chassis in an open position. [0018] Figure 7A shows an example embodiment of a brush cart assembly in which the relative position of the brush/shroud assemblies can be adjusted by operation of a screwjack, with the screwjack in its fully contracted position.

[0019] Figure 7B shows an example embodiment of a brush cart assembly in which the relative position of the brush/shroud assemblies can be adjusted by operation of a screwjack, with the screwjack in its fully extended position.

[0020] Figure 8 shows a partially exploded view of an example embodiment of a brush cart assembly having a float.

Description

[0021] Throughout the following description, specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0022] As used herein, the term Qlistal Dmeans in a direction towards the surface to be cleaned when the brush cart assembly is in an operating position. The term Cproximal Dmeans in a direction opposite to Qlistal D i.e. a direction away from the surface to be cleaned when the brush cart assembly is in an operating position.

[0023] With reference to Figure 1, an example embodiment of an underwater surface cleaning system is illustrated schematically. A brush cart assembly 10 is provided for removing debris from an underwater surface to be cleaned 23. In some embodiments, underwater surface 23 is the hull of a ship. Underwater surface 23 sits below the surface 35 of the water.

[0024] Loosened debris removed by brush cart assembly 10 is transported through an outlet hose 27 to a surface filtration unit 15 by a surface pump 11. Surface pump 11 and surface filtration unit 15 can be supported above the surface 35 of the water in any suitable manner. For example, in some embodiments, surface pump 11 and/or surface filtration unit 15 are mounted on a barge or other mobile vessel. In some embodiments, surface pump 11 and/or surface filtration unit 15 are provided on land, for example on a pier or other supporting structure, shown schematically as 37.

[0025] The surface pump 11 can be any suitable type of pump for moving fluid, for example a diaphragm pump, suction pump, screw pump, vane pump, or the like. The surface filtration unit 15 can be any suitable type of filtration unit for removing unwanted particulate, contaminants and/or debris from water. In some embodiments, outlet hose 27 is a flexible hose having a diameter in the range of between about 2 inches to about 6 inches (i.e. about 5 cm to about 15 cm) or any value therebetween, e.g. 3 inches or 4 inches. In some embodiments, different portions of the outlet hose can have different diameters, e.g. a first portion of the outlet hose can have a diameter in the range of about 3 inches and a second portion of the outlet hose can have a diameter in the range of about 4 inches. In some embodiments, use of an outlet hose with a smaller diameter provides better flexibility and/or is less susceptible to being displaced by currents.

[0026] With reference to Figure 2, an example embodiment of a brush cart assembly 10 is illustrated. Brush cart assembly 10 has a frame 12 supporting a plurality of brush/shroud assemblies 14 (three in the illustrated embodiment) and a plurality of surface contact points provided by wheels 16 (three in the illustrated embodiment) extending from legs 13 of the frame. In use, an operator moves brush cart assembly 10 along an underwater portion of a surface to be cleaned 23, so that brush/shroud assemblies 14 can be used to clean the surface. In some embodiments, wheels 16 are moved along the underwater surface to be cleaned by motors 17 so that brush cart assembly 10 can be more readily moved along the underwater surface to be cleaned.

[0027] With reference to Figures 3 and 4, an example embodiment of a brush/shroud assembly 14 has a shroud 18 partially surrounding a brush 20. In the illustrated embodiment, shroud 18 is generally circular in cross-section with a generally circular outer circumference 19 and an effluent outlet 26. One skilled in the art will recognize that the shape of shroud 18 could be varied somewhat, for example shroud 18 could be provided with a slightly oval rather than generally circular cross-sectional shape when viewed from the proximal direction. However, such other shapes may have decreased performance as compared with a generally circular cross- sectional shape.

[0028] In some embodiments, a plurality of bristles 22 are provided on brush 20, as in the illustrated embodiment. In some embodiments, bristles 22 are supported on brush 20 and oriented to project towards and/or slightly outside the distal portion 38 of shroud 18. In some example embodiments, bristles 22 can be retracted so that the distal ends of bristles 22 sit inside of distal portion 38 of shroud 18. In some example embodiments, bristles 22 can be retracted so that the distal ends of bristles 22 are up to approximately 2 inches (5 cm) inside of distal portion 38 of shroud 18, or any value between 0 inches and 2 inches, e.g. 0.25 inches, 0.50 inches, 0.75 inches, 1.0 inches, 1.25 inches, 1.50 inches or 1.75 inches. In some example embodiments, bristles 22 can be extended to project outside a distal portion 38 of shroud 18. In some example embodiments, bristles 22 can be extended to project outside distal portion 38 of shroud 18 by a distance in the range of up to approximately 0.25 inches (0.6 cm). In some example

embodiments, bristles 22 can be both extended and retracted relative to distal portion 38 of shroud 18 as outlined above.

[0029] Bristles 22 are positioned so they can be used to scrub an underwater surface 23 to be cleaned below the surface of the water 35. In some embodiments, brush/shroud assembly 14 is oriented so that bristles 22 project generally towards the surface contact points (wheels 16 in the illustrated embodiment), so that bristles 22 can be placed in contact with the surface to be cleaned where brush cart assembly 10 is in use. Shroud 18 is generally made from a flexible material, so that when brush/shroud assembly 14 is in use, shroud 18 can conform to various contours of the surface to be cleaned, and so that bristles 22 can contact the surface to be cleaned even if bristles 22 are retracted slightly inside shroud 18.

[0030] An impeller 24 is mounted to enable rotation within shroud 18, and shroud 18 includes an effluent outlet 26 so that rotational fluid flow and/or a centrifugal pump can be created within shroud 18. In the illustrated embodiment, effluent outlet 26 is provided on an outer portion of the circumference 19 of shroud 18. Impeller 24 is provided with one or more vanes 25 to apply force to the fluid contained within shroud 18. Effluent outlet 26 is coupled to a surface pump, shown schematically as 11, and filtration unit, shown schematically as 15, via an outlet hose 27 (Figure 1). The combined effect of the rotation of impeller 24 (and optionally brush 20) within shroud 18 and the removal of fluid through effluent outlet 26 provides rotational flow

characteristics that help to capture debris within shroud 18 and transport fluid and debris through effluent outlet 26. In some embodiments the combined effect of the rotation of impeller 24 (and optionally brush 20) within shroud 18 and the removal of fluid through effluent outlet 26 provides a centrifugal pumping action.

[0031] Shroud 18 helps to contain any debris released in the cleaning process, so that such debris is directed to the surface pump and filtration unit via outlet hose 27 rather than being distributed into the surrounding environment. In some embodiments, the suction force applied by the surface pump can also assist in holding brush/shroud assembly 14 onto the surface to be cleaned 23, in addition to the suction forces produced by rotation of impeller 24 and brush 20 as described below.

[0032] In the illustrated embodiment, a brush mounting plate 28 is provided for rotatably mounting brush 20 within shroud 18. In some embodiments, brush 20 is releasably coupled to brush mounting plate 28, for example by snap-fit engagement means, locking nuts, or by screws, so that brush 20 can be readily replaced as it wears. In the illustrated embodiment, brush mounting plate 28 includes features that allow the quick connection of brushes of different types. The distal side of brush mounting plate 28 is provided with a plurality of projections 31 that can engage with corresponding recesses provided on the proximal side of brush 20 in a snap-fit engagement. Brush mounting plate 28 also includes a central distally projecting threaded nipple 33, which can receive a threaded nut 39 to secure brush 20 to brush mounting plate 28.

[0033] An impeller flange 29 is provided that can be secured to impeller 24 in any suitable manner (for example, by passing a pair of bolts through a pair of aligned apertures in impeller flange 29 and impeller 24 in the illustrated embodiment). Impeller flange 29 is provided with suitable features to enable it to cause rotation of impeller 24 within shroud 18. For example, in the illustrated embodiment, the impeller flange 29 may be mounted to the shaft of motor 30 with a bolt and key way (not shown) so that motor 30 can be used to rotate impeller flange 29 and therefore impeller 24.

[0034] In some embodiments, including the illustrated embodiment, a shroud support plate 34 is provided to support flexible shroud 18 and provide a point of securement for motor 30. Shroud support plate 34 is generally circular in shape to correspond with the general shape of shroud 18. In the illustrated embodiment, the portion of shroud 18 that extends outwardly from the edges of shroud support plate 34 has a slight curvature in the proximal direction (best seen in Figure 4). However, other configurations could be used for this portion of shroud 18.

[0035] A hydraulic motor 30 is provided to rotate impeller 24 and brush 20. In the illustrated embodiment, a brush motor housing plate 32 is provided for mounting hydraulic motor 30 to brush/shroud assembly 14. Shroud support plate 34 is coupled to brush motor housing plate 32 in any suitable manner (for example, by passing bolts through corresponding apertures to secure the two components together), with shroud 18 interposing the two.

[0036] In use in an example embodiment, hydraulic motor 30 is used to rotate brush 20, impeller 24, brush mounting plate 28, and impeller flange 29. Brush/shroud assembly 14 is held proximate to the underwater surface to be cleaned via rotating flow forces created by the spinning of brush bristles 22 and impeller 24 within shroud 18. To some extent, brush assembly 14 can also be held proximate to the underwater surface to be cleaned via suction forces produced by a surface pump connected to brush/shroud assembly 14 via the outlet hose 27. Brush bristles 22 apply a mechanical brush or scrubbing force to the surface to be cleaned, to assist in loosening fouling or surface debris from the surface to be cleaned.

[0037] The movement of impeller 24 and brush 20 within shroud 18 provides fluid suction forces to remove water and loosened debris (for example, fouling or paint removed from the surface to be cleaned) through effluent outlet 26 and outlet hose 27 to the surface pump and filtration system. Impeller 24 forces fluid towards the outside edges of a cavity 36 defined within shroud 18, thereby producing a region of low pressure near the centre of cavity 36. A portion of the fluid within cavity 36 is forced out effluent outlet 26, carrying loosened debris with it.

[0038] When brush/shroud assembly 14 is in use, the suction force provided by the surface pump coupled with the movement of impeller 24 and brush 20 within shroud 18 creates a rotational flow having characteristics similar to that of a vortex that pulls brush/shroud assembly 14 towards the surface to be cleaned. Suction forces can be obtained without the surface pump; however, in some embodiments the surface pump increases the suction flow rate to maximize suction forces and maximize collection of debris by brush/shroud assembly 14.

[0039] In some example embodiments, the suction forces created by the combined action of rotational fluid flow within shroud 18 and the surface pump can be in the order of approximately 0 to 600 kg when impeller 24 and brush 20 are rotated at a speed in the range of approximately 575 to 650 revolutions per minute (r.p.m).

[0040] The use of different types of brushes in brush/shroud assembly 14 may change the maximum suction force that can be created. For example, depending on the condition of the surface to be cleaned and the type and degree of fouling present, different brushes may be used, e.g. nylon bristles to remove algal growth; relatively stiffer bristles such as stainless steel bristles to remove harder materials such as growth of molluscs or crustaceans. A person skilled in the art can select an appropriate brush for cleaning a given underwater surface given the condition of that underwater surface.

[0041] In some embodiments, a distal portion 38 of shroud 18 is positioned so that bristles 22 extend slightly beyond shroud 18, i.e. so that shroud 18 does not actually make contact with or seal to the surface to be cleaned when brush cart assembly 10 is in use. This leaves a slight gap 42 (Figure 4) between the distal end 38 of shroud 18 and the surface to be cleaned. Provided that the distal portion 38 of shroud 18 remains sufficiently close to the surface to be cleaned (i.e. provided that gap 42 is not too large) so that the suction force produced by the rotation of impeller 24 and brush 20 is retained, loosened debris should not escape to the surrounding waters to a significant extent. In some embodiments, gap 42 ranges in size from about 0 inches to about 0.5 inches (i.e. about 0 cm to about 1.25 cm), or any value therebetween including e.g. about 0.25 inches.

[0042] As the size of gap 42 is increased, the suction forces created as described above would be increased. However, when gap 42 between the distal end 38 of shroud 18 and the surface to be cleaned becomes too large, suction will be lost and brush/shroud assembly 14 will tend to fall away from the surface to be cleaned 23. In some example embodiments, it is believed that when gap 42 increases in size to between about 2.5 inches and about 5 inches (about 6 cm to about 13 cm), suction forces may be lost.

[0043] Without being bound by theory, it is believed that when suction forces created by rotational flow are present as outlined above, water and any loosened particles of debris that are forced outwardly within cavity 36 will tend to follow the path of travel indicated by arrows 40A, 40B, 40C and 40D (Figure 4). In the illustrated embodiment, shroud 18 has an inwardly angled peripheral portion 21 that extends between outer circumference 19 and distal portion 38 of shroud 18. Inwardly angled peripheral portion 21 helps to redirect fluid and debris inwardly towards the centre of shroud 18, as illustrated by arrow 40B. While inwardly angled peripheral portion 21 has been illustrated as being generally straight, inwardly angled peripheral portion 21 could be provided with other shapes, so long as such shape results in redirection of fluid and debris inwardly, e.g. inwardly angled peripheral portion 21 could be provided with a slightly curved shape.

[0044] The stream of water and any particles of debris will thus tend to be redirected inwardly towards the centre of cavity 36 by the inside surfaces of the walls of shroud 18, and therefore will not escape to a significant extent through gap 42 (if present) into the surrounding waters. The redirected fluid and/or debris particle is then transported through the low pressure region within cavity 36 by forces generated primarily from impeller 24, back toward the inside surfaces of the walls of shroud 18 (indicated by arrow 40D), until the fluid and/or debris particle is in close proximity to effluent outlet 26, whereby the fluid and/or debris particle exits shroud 18 and is transported to the surface filtration unit by the surface pump. In some embodiments, the retention and removal of loosened particles of debris by brush/shroud assembly 14 may be so high that almost no visible particulate is released into the surrounding water.

[0045] In the illustrated embodiment, a brush chassis 50 is provided to support brush/shroud assemblies 14 on brush cart assembly 10. In some embodiments, including the illustrated embodiment, brush chassis 50 is provided with features (described in more detail below) that provide brush/shroud assemblies 14 with a range of motion to allow brush cart assembly 10 to be used to clean uneven surfaces and/or curved surfaces, as well as generally flat surfaces. In some embodiments, each one of the brush/shroud assemblies 14 on a brush cart assembly 10 is provided with individual freedom of movement relative to the other brush/shroud assemblies 14 on the brush cart assembly 10. In some embodiments, each one of the brush/shroud assemblies 14 on brush cart assembly 10 is provided with three degrees of freedom.

[0046] With reference to Figure 5, brush chassis 50 has a base 49 with three support arms 52 extending from base 49. Each support arm 52 has a central hinge region 54, which will be described in greater detail below, and a universal swivel joint 56 at its distal end. Each universal swivel joint 56 is coupled to one of the brush/shroud assemblies 14. In the illustrated embodiment, each universal swivel joint includes a base 55 and a pair of arms 57 that project distally from either end of base 55.

[0047] In the illustrated embodiment, each universal swivel joint 56 includes a pair of opposed receptacles 58 provided on the inside surfaces of arms 57. Each receptacle 58 receives a corresponding pin 60 provided on the proximate portion of brush/shroud assembly 14, so that each brush/shroud assembly 14 is rotatably engaged with a universal swivel joint 56. This rotational engagement of brush/shroud assembly 14 with universal swivel joint 56 provides brush/shroud assembly 14 with a first degree of freedom relative to frame 12. Brush/shroud assembly 14 can rotate about axis 62 by virtue of this rotational engagement, as illustrated by arrow 64.

[0048] In some embodiments, rotation about axis 62 is constrained to maintain reasonable anticipated operating orientations of brush shroud assembly 14. In one example embodiment, rotation about axis 62 is constrained to a maximum angle of approximately 45° proximally towards base 49 of brush chassis 50 and up to approximately 90° distally away from base 49 of brush chassis 50, for a total possible range of motion about axis 62 of approximately 135°.

[0049] Each universal swivel joint 56 is in turn rotatably coupled to a distal end of a

corresponding support arm 52. This rotatable coupling provides brush assembly 14 with a second degree of freedom relative to frame 12. In the illustrated embodiment, an aperture 66 is provided through base 55 so that base 55 (and therefore arms 57, which are integrally formed with or affixed to base 55) can rotate about a securing pin 68 provided at the distal end of support arm 52. This rotatable connection allows universal swivel joint 56 to rotate about an axis 70, as indicated by arrow 72. This provides brush/shroud assembly 14 with a second degree of freedom relative to frame 12. In some embodiments, universal swivel joint 56 is free to rotate at any angle about axis 70, constrained only by the physical positioning of elements of brush cart assembly 10 (i.e. at some angle of rotation, brush/shroud assembly 14 may make physical contact with some element of brush cart assembly 10, for example arms 13, hydraulic lines or the like, and thereby be prevented from further rotation). In some example embodiments, brush/shroud assembly 14 can rotate up to about 30° in either direction about axis 70.

[0050] Each support arm 52 includes a hinge region 54. Hinge region 54 allows first and second portions 52A, 52B of support arm 52 to rotate relative to one another about a hinge 74. Thus, first and second portions 52A, 52B can rotate relative to one another about axis 76, as indicated by arrow 78. This connection provides brush/shroud assembly 14 with a third degree of freedom relative to frame 12. Figure 6 shows hinge region 54 in an open configuration, i.e. wherein first and second portions 52A, 52B of support arm 52 have rotated away from one another about pin 74.

[0051] In the illustrated embodiment, a pair of springs 80 is operatively connected between first and second portions 52A, 52B of support arm 52, one on either side of support arm 52. Springs 80 apply a force to retain first and second portions 52A, 52B adjacent to one another when there is no counteracting force exerted on brush/shroud assembly 14. In use, suction generated by brush/shroud assembly 14 pulls brush/shroud assembly 14 (and therefore second region 52B of support arm 52) in the distal direction towards the surface to be cleaned 23, so that first and second portions 52A, 52B are pivoted apart from one another around hinge 74. Springs 80 apply a counteracting force that tends to pull first and second portions 52A, 52B of support arm 52 towards each other about hinge 74. Springs 80 should be selected to have a sufficient size and stiffness to counteract the expected suction forces generated by brush/shroud assembly 14, but still allow some pivoting of first and second portions 52A, 52B under a range of reasonable expected operating conditions. Springs 80 can be made from any suitable corrosion resistant material. In some example embodiments, spring 80 has a stiffness of under about 500 pounds per inch per spring. In some embodiments, only a single spring 80 could be used.

[0052] Without being bound by theory, it is believed that provision of a hinge region 54 in support arms 52 allows some movement of individual brush shroud assemblies independently of one another on a single brush cart assembly 10, e.g. distally or proximally towards or away from the surface to be cleaned. This may enhance cleaning of surfaces such as curved surfaces by the brush cart assembly 10.

[0053] The three degrees of freedom of brush/shroud assembly 14 relative to frame 12 provided as outlined above provide brush/shroud assembly 14 with a good range of motion so that brush/shroud assembly 14 can move relative to frame 12 as the contours of the surface to be cleaned 23 change, including on curved surfaces such as ship hulls. For example, ships hulls are often uneven in shape, and it can be difficult for the operator of a hull cleaning apparatus to ensure consistent positioning of the brushes relative to the hull of the ship, particularly when multiple brushes are present on a single brush cart.

[0054] While in the illustrated embodiment, brush cart assembly 10 has been illustrated as having three brush/shroud assemblies 14, any suitable number of brush/shroud assemblies could be used. For example, in some embodiments, anywhere between 2 and 7 brush/shroud assemblies or more may be used, including any value therebetween, e.g. 4, 5 or 6. In some embodiments, three brush/shroud assemblies are used to increase the cleaning width provided by a given brush cart assembly as compared with using only two brush/shroud assemblies, while not rendering the construction of such brush cart assembly unreasonably complex. [0055] In some embodiments, the force of brush bristles 22 on surface to be cleaned 23 and/or the distance of brush/shroud assemblies 14 from surface to be cleaned 23 can be adjusted by lifting brush/shroud assembly 14 away from the surface to be cleaned and/or allowing brush/shroud assembly 14 to move towards the surface to be cleaned. Any suitable mechanism can be used to adjust the position of brush/shroud assemblies 14 relative to the surface to be cleaned 23, for example, hydraulic cylinders, gears, mechanical means such as a screwjack, or the like.

[0056] In some embodiments, brush/shroud assembly 14 is lifted by the use of a mechanical screwjack 44 that is operatively coupled to adjust the position of brush chassis 50 relative to frame 12. In the illustrated embodiment, the positions of the surface contact points of brush cart assembly 10 (wheels 16 in the illustrated embodiment) relative to frame 12 are fixed. However, the position of brush shroud assemblies 14 relative to wheels 16, and therefore the surface to be cleaned 23, can be changed by adjusting the position of screwjack 44. In use, an operator can feel when holding brush cart assembly 10 whether brush/shroud assemblies 14 are moving toward or away from the operator (i.e. moving toward or away from frame 12), and can adjust the positioning of screwjack 44 accordingly to maintain a desired distance between the surface to be cleaned 23 and brush/shroud assemblies 14, even when the contours of the surface to be cleaned 23 are somewhat uneven.

[0057] Figure 7 A shows an example embodiment of a brush cart assembly 10 with screwjack 44 in its fully contracted position. In this position, brush/shroud assemblies 14 are located as far in the proximal direction as possible from wheels 16, i.e. as close to frame 12 as possible. Figure 7B shows the example brush cart assembly 10 with screwjack 44 in its fully extended position. In this position, brush/shroud assemblies 14 are forced in the distal direction away from frame 12, and are as close to wheels 16 as possible. Thus, operation of screwjack 44 allows an operator to adjust the distance between the surface to be cleaned 23 and brush/shroud assemblies 14. A handle 92 coupled to a steering pipe can be used by an operator to control the movement and steering of brush cart assembly 10. [0058] Figure 8 shows a partially exploded view of an example embodiment of a brush cart assembly with a float 98. In the illustrated embodiment, float 98 partially encases portions of brush cart assembly 10. Float 98 is provided to give brush cart assembly 10 a desired level of buoyancy, to make it easier for an operator to use brush cart assembly 10 underwater. In some embodiments, the buoyancy of float 98 is selected to provide brush cart assembly 10 with a relatively neutral buoyancy.

[0059] The view of Figure 8 also shows hydraulic connections 94 for the connection of hydraulic lines (omitted from the figures for clarity), and a suction hose manifold 96. In some embodiments, wheels 16 are driven by motors 17 to move brush cart assembly 10 along surface to be cleaned 23. In some embodiments, all wheels 16 of brush cart assembly 10 are driven to provide all-wheel drive. In some embodiments, wheels 16 are operated with traction control providing for limited slip. For example, at some times, one wheel 16 may rotate at a faster speed than the other wheels 16, for example to allow brush cart assembly 10 to turn a comer.

[0060] In some embodiments, brush 20 is rotated at an approximately constant speed. In some embodiments, rotation of brush 20 and impeller 24 at an approximately constant speed helps to ensure a consistent suction force. In the regular course of cleaning an underwater surface, in some areas the amount of debris to be removed may be relatively heavy, while in other areas the amount of debris to be removed may be relatively light, for example due to differences in the rate of growth of biomass in different areas. The speed of rotation of brush 20 will tend to be slower in areas where there is a relatively heavy amount of debris to be removed, and faster in areas where there is a relatively lighter amount of debris to be removed. Thus, in some embodiments, adjustments are made to the speed of rotation of brush 20 as it moves along the surface to be cleaned, to compensate for such variations and maintain an approximately constant speed of rotation.

[0061] Any suitable materials can be used for the construction of brush/shroud assembly 14 and brush cart assembly 10. For example, in some embodiments, components of the brush cart such as brush chassis 50 and support arms 52 can be made from a suitable metal such as aluminum or stainless steel. Some components of brush cart assembly 10 such as shroud 18 and float 98 can be made from any suitable plastic, for example polyurethane. In some embodiments, shroud 18 is made from a flexible, abrasion-resistant plastic. In some embodiments, shroud 18 is made from a suitable nonflexible material, which may be plastic. In some embodiments, float 98 is made from polyurethane with a protective coating. In some embodiments, float 98 is made from closed-cell high density high strength foam, e.g. to withstand compressive forces caused by water depth. Example embodiments of brush bristles 22 can be made from any suitable material, for example, polypropylene, nylon, stainless steel, or the like.

[0062] In some embodiments, a hydraulic control block 90 is provided (Figure 2) to operate a hydraulic control system. The hydraulic control block can be used to operate the screw jack 44 to adjust the position of the brush chassis 50 with respect to the surface to be cleaned. The hydraulic control block can also be used to control the motors that rotate brush 20 and impeller 24, and the motors that move wheels 16.

[0063] While a number of exemplary aspects and embodiments are discussed herein, those of skill in the art will recognize certain modifications, permutations, additions and subcombinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are consistent with the broadest interpretation of the specification as a whole.

Claims

WHAT IS CLAIMED IS:

1. A brush/shroud assembly for cleaning an underwater surface, the brush/shroud assembly comprising:

a brush for loosening debris on the underwater surface;

a shroud at least partially enclosing the brush to contain the debris;

an impeller rotatably mounted within the shroud; and

an effluent outlet provided in the shroud for removing the debris from the shroud, wherein rotation of the impeller provides a force to drive fluid and the debris through the effluent outlet.

2. A brush/shroud assembly as defined in either one of claims 1 or 2, wherein the shroud has a generally circular outer circumference; wherein the effluent outlet is provided on an outer circumference of the shroud; and/or wherein the shroud is flexible or rigid.

3. A brush/shroud assembly as defined in claim 1, wherein:

rotation of the impeller and the flow of the fluid and the debris through the effluent outlet provides a centrifugal pumping action, and optionally wherein a suction force generated by the rotation of the impeller pulls the brush assembly towards the underwater surface when the brush assembly is in use; and/or

wherein suction provided by a surface pump in fluid communication with the effluent outlet assists the removal of the debris from the shroud, and optionally assists to pull the brush/shroud assembly towards the underwater surface when the brush/shroud assembly is in use.

4. A brush/shroud assembly as defined in any one of claims 1 to 3, wherein the shroud comprises an inwardly angled peripheral portion extending between the outer circumference of the shroud and a distal portion of the shroud, and wherein the inwardly angled peripheral portion is optionally straight or curved.

5. A brush/shroud assembly as defined in any one of claims 1 to 4, further comprising a drive motor for driving the brush and/or the impeller.

6. A brush/shroud assembly as defined in any one of claims 1 to 5, wherein:

the brush comprises a rotatable brush;

the brush is operated at an approximately constant speed of rotation in use; and/or the impeller comprises one or more vanes for applying force to the fluid.

7. A brush/shroud assembly as defined in any one of claims 1 to 6, wherein bristles of the brush project slightly outwardly of a distal portion of the shroud.

8. A brush/shroud assembly as defined in claim 7, wherein the bristles of the brush project outwardly of the distal portion of the shroud by a distance of between 0 and 5 cm.

9. A brush/shroud assembly as defined in any one of claims 1 to 6, wherein bristles of the brush sit slightly inwardly of a distal portion of the shroud.

10. A brush/shroud assembly as defined in claim 9, wherein the bristles of the brush sit inwardly of the distal portion of the shroud by a distance of between 0 and 0.6 cm.

11. A brush cart for cleaning an underwater surface, the brush cart comprising:

a frame;

a plurality of surface-contact points coupled to the frame for contacting the underwater surface, wherein the surface-contact points optionally comprise wheels; a brush chassis coupled to the frame;

at least one brush/shroud assembly extending from the brush chassis towards the surface-contact points, the brush/shroud assembly comprising:

a rotatable brush having bristles oriented generally towards the surface-contact points;

a rotatable impeller;

a drive motor for driving the brush and/or the impeller; and a shroud enclosing the brush and the impeller to define a cavity for containing debris released as the underwater surface is cleaned.

12. A brush cart for cleaning an underwater surface, the brush cart comprising:

a frame;

at least one brush/shroud assembly as defined in any one of claims 1 to 10 extending from the brush chassis towards the surface-contact points.

13. A brush cart as defined in either one of claims 11 or 12, further comprising a mechanism operable to adjust the position of the brush chassis relative to the frame to enable the distance between the brush chassis and the underwater surface to be adjusted in a proximal or distal direction, wherein the mechanism optionally comprises a screw jack coupled between the frame and the brush chassis.

14. A brush cart as defined in any one of claims 11 to 13, wherein the brush/shroud assembly is provided with three degrees of freedom relative to the frame.

15. A brush cart as defined in claim 14, wherein two of the three degrees of freedom are provided by a universal swivel joint coupled between the brush chassis and the brush/shroud assembly.

16. A brush cart as defined in claim 15, wherein one of the degrees of freedom is provided by the rotational engagement of opposed receptacles disposed on the distal portions of arms of the universal swivel joint with corresponding pins provided on a proximal portion of the brush/shroud assembly.

17. A brush cart as defined in any one of claims 15 to 16, wherein one of the degrees of freedom is provided by the rotational engagement of an aperture formed through a base of the universal swivel joint with a corresponding securing pin provided at a distal portion of an arm of the brush chassis.

18. A brush cart as defined in any one of claims 14 to 17, wherein one of the degrees of freedom is provided by a hinged arm extending between a base of the brush chassis and the brush/shroud assembly.

19. A brush cart as defined in claim 18, wherein the hinged arm comprises first and second arm portions pivotally coupled with a pin and a spring positioned to apply compressive force to retain the first and second arm portions adjacent to one another.

20. A brush cart as defined in any one of claims 11 to 19, comprising 2, 3, 4, 5 or 6

brush/shroud assemblies, each one of the brush/shroud assemblies being contained within a corresponding shroud.

21. A brush cart as defined in any one of claims 11 to 20, wherein the surface-contact points comprise wheels, and a hydraulic system is provided to drive each one of the wheels, optionally wherein the hydraulic system provides the wheels with limited-slip.