An Apparatus for underwater excavation

Field of the Invention

The present invention relates to an excavation apparatus, for example to Mass Flow Excavation (MFE) systems suitable for use in, for example, underwater construction, excavation and extraction of materials.

Pumps are mechanical devices that use differential pressure to move fluids. They are commonly used in a wide variety of industrial applications. There are different types of pumps, including for example centrifugal (or radial) pumps, propeller (or axial) pumps or mixed flow pumps.

Centrifugal pumps use a rotating impeller to create a region of low pressure which entrains a surrounding fluid or slurry, drawing it through the impeller where the rotor blades are shaped to accelerate the fluid radially at a direction perpendicular to the axis of rotation, and into a diffuser, creating a high pressure discharge of the fluid or slurry. Centrifugal pumps can generally operate at high pressures, but at lower flow rates than those of axial or propeller pumps.

Axial pumps use generally the same principle, however, the pump is positioned in line with the axis of rotation of the impeller and the fluid is drawn through the impeller, and exits on the downstream side of the impeller. Axial pumps can operate at significantly higher flow rates, but at lower pressures than centrifugal pumps.

Mixed flow pumps offer a combination of both radial and axial pumps, in which the direction of flow imparted on the fluid by the impeller or blades is generally at an angle or oblique relative to the axis of rotation of the impeller or blades, where the flow is drawn through the impeller and accelerated both axially and radially. This results in higher operating pressures than axial pumps, whilst delivering higher flow rates than centrifugal pumps.

However, a limitation is present in each of these types of pumps since the rotor blades rotate within a stationary housing, and as such, a gap exists between the ends of the rotor blades and the interior face of the casing. Across this gap, a loss in fluid pressure occurs, thus affecting the overall efficiency of the pump. This pressure drop reduces as the gap size decreases; however, this introduces exceedingly fine tolerances in the components, and consequently increases the cost of manufacture. Mass flow excavation (MFE) is a method of underwater excavation commonly used in offshore industries such as oil and gas, and wind and tidal energy generation, in which material is removed or displaced by the mass flow of a fluid driven by a pump system. High mass-high velocity flows of fluid or slurry; or high fluid or slurry pressure jets, are generated which can remove, displace or cut underwater materials such as silt, rock or metal. This technique is commonly used for the construction of underwater trenches, preparation of subsea workspaces, removal of dug-in objects or the decommissioning and abandonment of subsea infrastructure.

MFE equipment generally comprises high power axial or propeller pumps or other such pumping mechanisms driven by hydraulic or electric motors. The axial or propeller pump entrains and accelerates a fluid through the pump to the downstream side of the pump, where it exits through a nozzle. The nozzle aperture is sized so as to increase the velocity of the fluid flow, consequently increasing the dynamic energy content, or power, of the fluid flow, as expressed by the form:

to create a jet of fluid wherein the product of the mass flow rate and velocity V, also referred to as the impulse of the fluid, is great enough to move soil and larger objects. This allows it to be used for the aforementioned subsea operations.

For optimum performance at greater working distances between the device and the work surface, the trajectory of the operating fluid jet should ideally be straight with a high axial velocity and low swirling velocity.

It can be appreciated that with the use of suction devices in an underwater environment, the flow of water can entrain solid particulate matter or large rocks which can be drawn into the rotor and damage the blades or rotor, requiring their repair or replacement.

MFE equipment generally uses a propeller-type or centrifugal pump means where the rotor of the pump is rotatably mounted in a stationary casing. This arrangement requires disassembly of the rotor casing during maintenance or repair before the rotor can be accessed for further servicing. Such components are typically heavy and bulky, and therefore disassembly can be difficult and time consuming. With mass flow excavation equipment, the simplicity and ease of maintenance of the pumping means can have a direct bearing on the usefulness and performance of the apparatus.

In industrial applications, for example in the oil and gas industry, the associated costs of downtime of machinery can be vast. It is therefore a problem that in the event that a machine is damaged, disassembly causes disruption. Further, adjustments to the machinery may be required to suit different operating conditions. Thus the removal and replacement of the rotor with one of a different specification also causes downtime.

It is an object of the present invention to obviate and/or mitigate the limitations and/or disadvantages associated with the prior art and/or with conventional systems.

Summary of the Invention

According to a first aspect of the present invention, there is provided an excavation apparatus comprising:

a casing defining a fluid passageway, the casing comprising a stationary portion and a rotatable portion; and

a pump configured for moving fluid through the passageway, the pump comprising a rotor,

wherein the rotor is attached to the rotatable portion of the casing.

The rotor may be fixed, or connected to, e.g. may be permanently attached, fixed, welded or connected to, the rotatable portion of the casing.

The rotatable portion of the casing may be provided at or near, or may define an end of fhe casing, e.g. a first end thereof.

The stationary portion of the casing may be provided at or near, or may define an end of the casing, e.g. a second end thereof.

The first end and the second may be separate, e.g. may be opposite one another and/or may be provided at opposite ends of the casing. The casing may comprise two ends, a first end and a second end, typically located opposite the first end.

In blowing or jetting mode, a flow or jet of fluid may be ejected or expelled from a working end of the apparatus towards a work surface, wherein the working end may be defined by the end of the apparatus used to perform the task, e.g. ejecting or expelling a flow or jet of fluid. The working end may be at, adjacent, or near or may be facing the work surface.

In use, in blowing or jetting mode, a flow of fluid may flow from the first end to the second end. In blowing or jetting mode, the first end may comprise, may be or may define an inlet of the casing or passageway and/or the second end may comprise, may be or may define an outlet of the casing or passageway. In blowing or jetting mode, the working end may comprise, may be or may define the second end. In such instance, a flow of fluid may move or may be forced from the first end to the second end. Alternatively, for example if the direction of the rotation of the motor is reversed, the working end may comprise, may be or may define the first end. In such instance, in blowing or jetting mode, a flow of fluid may flow from the second end to the first end. Thus, the second end may comprise, may be or may define an inlet of the casing or passageway and/or the first end may comprise, may be or may define an outlet of the casing or passageway.

In suction mode, the working end may be defined by the end of the apparatus used to draw the flow of fluid into the apparatus.

In use, in suction mode, a flow of fluid may flow from the second end to the first end. In suction mode, the first end may comprise, may be or may define an outlet of the casing or passageway and/or the second end may comprise, may be or may define an inlet of the casing or passageway. In suction mode, a flow of fluid may be drawn into the apparatus through the working end. The working end may comprise, may be or may define the second end.

Alternatively, for example if the direction of the rotation of the motor is reversed, the working end may comprise, may be or may define the first end. In such instance, in suction mode, a flow of fluid may move from the first end to the second end. In such instance, in suction mode, the first end may comprise, may be or may define an inlet of the casing or passageway, and/or the second end may comprise, may be or may define an outlet of the casing or passageway.

The rotatable portion of the casing may comprise, may define, or may be a shroud.

The casing may be generally cylindrical and/or may be generally symmetrical about a longitudinal axis.

The casing may comprise at least two portions. The at least two portions may comprise the stationary portion and the rotatable portion.

The rotatable portion may be rotatable about an axis, e.g. a/the longitudinal axis of the casing and/or of the rotor.

The rotatable portion may be located at or may comprise the first end of the casing. The stationary portion may be located at and/or may comprise the second end of the casing.

The stationary portion and the rotatable portion of the casing may be separated at a separation location, e.g. by a gap or clearance.

The rotatable portion may be rotatably moveable relative to the stationary portion.

The rotor may comprise one or more rotor blades, typically a plurality of rotor blades. In use, rotation of the rotor, e.g. rotor blades, may cause movement of fluid through the casing, e.g. passageway thereof. The rotatable portion of the casing may be fixediy or permanently attached to at least one rotor blade, e.g to a plurality of rotor blades, typically to the rotor blades By such provision, rotation of the rotor may cause rotation of the rotatable portion of the casing.

The rotor blades and rotatable portion of the casing may rotate together as a single unit. By such provision, there is no gap between the ends of the rotor blades and the interior face of the casing, and thus no pressure loss occurs between the rotor blades and the casing. This provides improved efficiency in the region of the rotor blades when compared to a design in which rotor blades rotate within a stationary casing.

The pump, e.g. rotor thereof, may be located within the casing. The pump, e.g. rotor thereof, may be located within a central portion of the casing, e.g. relative to or about a longitudinal axis of the casing. At least a portion of the passageway may be provided between an inner surface of the casing and an outer surface of the pump or housing thereof.

The casing may further comprise a nozzle which may be attached to the casing.

The nozzle may be provided at the first end or at the second end of the casing. T pically, the nozzle may be provided at the second end of the casing.

The nozzle may comprise one or more sections.

The one or more sections of the nozzle may be positioned at different angles to allow for varying levels of convergence.

The nozzle may be separate from the casing.

The nozzle may be attached to the casing via conventional means, e.g. attachment means, such as nuts and bolts, welded connections, or the like.

The nozzle may be integral to the casing and may be comprised, formed, or manufactured as a single unit, e.g. may be unitary with the casing.

The casing may comprise a diffuser.

The diffuser may be defined by or may form part of the rotatable portion of the casing. A portion of the diffuser may be defined by the rotatable portion of the casing.

The rotatable portion may be tapered.

The rotatable portion may have a first end which may be provided at or near the first end of the casing and/or apparatus. The rotatable portion may have a second end which may be provided near or adjacent the stationary portion of the casing.

A diameter of the first end of the rotatable portion of the casing may be less than or equal to, typically less than, a diameter at the second end of the rotatable portion of the casing.

The diameter of the second end of the rotatable portion of the casing may be less than the diameter of the stationary portion of the casing near or adjacent the rotatable portion. The diameter of the second end of the rotatable portion may be substantially equal to the diameter at the second end of the stationary portion, e.g near or adjacent the rotatable portion

In the case of the diameter of the second end of the rotatable portion being less than the diameter at the second end of the stationary portion of the casing (near or adjacent the rotatable portion), the stationary portion of the casing may further comprise a truncated diffuser which may be provided or interposed between the rotatable portion of the casing and the stationary portion of the casing

The truncated diffuser may be tapered and may have a diameter at its first end (an end at or near the rotatable portion) generally equal to that of the second end of the rotatable portion of the casing. The tapered truncated diffuser may have a diameter at its second end (an end at or near the stationary portion) generally equal to that of the first end of the stationary portion of the casing.

In the case of the diameter of the second end of the rotatable portion being equal to that of the stationary portion of the casing near or adjacent the rotatable portion, a truncated diffuser may not be tapered and may be parallel sided.

In the case of the diameter of the second end of the rotatable portion being equal to that of the stationary portion of the casing, a truncated diffuser may not be required and may be omitted, such that the rotatable portion of the casing is adjacent the stationary portion of the casing.

The truncated diffuser may be separate from the stationary portion of the casing and may be attached via a conventional fixing means such as nuts and bolts, welded connections, or the like. The truncated diffuser may be integral to the stationary portion of the casing and may be manufactured as a single unit.

The pump may have a generally circular cross section

The pump may be located substantially centrally within the casing or passageway, and may share a common longitudinal axis with the casing.

The pump may be located within the casing such that at least a portion of the fluid passageway may be defined by the space between an outside surface of the pump, e.g. housing thereof, and an inside surface of the casing.

The pump may have a diameter less than that of the casing such that an annular channel may be defined along the longitudinal axis of the excavation apparatus between the outside surface of the pump and the inside surface of the casing.

The annular channel may define at least a portion of the fluid passageway. The pump may have a first end provided near or facing towards the first end of the casing. The pump may have a second end provided near or facing towards the second end of the casing.

The first end of the pump may be generally cylindrical and/or parallel sided.

The first end of the pump may be generally parallel sided such that the annular channel created between the first end of the pump and the casing is also generally parallel sided.

The first end of the pump may be tapered.

The first end of the pump may be generally tapered such that the annular channel created between the pump and the casing is also generally tapered.

The second end of the pump may be generally conical and/or may taper to a second pump end. In an embodiment, the second end of the pump may form a generally rounded nose bullet shape.

The second end of the pump may be tapered such that the annular channel created between the second end of the pump and the casing diverges such that the cross sectional area of the annular channel increases as it approaches the second end.

The annular channel defined between the second end of the pump and the casing may diverge.

A plenum may be defined between the pump and the casing.

One or more baffle(s) may be disposed within the fluid passageway and/or annular channel and/or plenum. One or more baffle(s) may be located between the pump and the casing.

The annular channel may be segmented into a plurality of (smaller) channels by the baffle(s).

The fluid flow may be directed, deflected, aligned or guided by the baffle(s).

The baffle(s) may comprise plates located between the pump and the casing.

The baffle(s), e.g., plates may be disposed in a longitudinal plane, in a transverse plane, in an angled plane, or the baffle(s), e.g., plates may be disposed in any combination of the aforementioned planes.

The baffle(s), e.g., plates may be flat or planar.

The baffle(s), e.g., plates may be curved, angled or shaped.

The baffle(s), e.g., plates may deflect, direct or align the flow of the fluid through the fluid passageway or the casing.

The pump may be configured for moving fluid through the passageway or casing.

The pump may comprise a rotor assembly and a motor housing. The pump may be located within the casing such that the fluid passageway is defined between an outside surface of the pump, e g. housing thereof, and an inside surface of the casing.

The pump may be an axial pump.

The pump may be a centrifugal pump.

Advantageously, the pump may comprise, or may be a mixed flow pump. By such provision the pump may deliver higher operating pressures than axial pumps, and higher flow rates than centrifugal pumps.

The pump may be powered by a motor. The motor may be provided within the motor housing.

The rotor assembly may comprise a rotor, rotor blades and the rotatable portion of the casing.

The rotor may be generally cylindrical and/or symmetrical about a central longitudinal axis.

The rotor may share a common longitudinal axis to the casing.

The rotor blades may be rigidly or permanently attached or fixed to the rotor. The rotor blades may be rigidly or permanently attached or fixed to the rotatable portion of the casing.

The rotatable portion of the casing may be, may comprise or may define a shroud.

The shroud may form part of the casing. The shroud may define or may form the rotatable portion of the casing.

Preferably the rotor may be attached or connected to the rotatable portion of the casing, or shroud, via the rotor blades. By such provision the rotatable portion or shroud may be rigidly attached to the rotor blades to form an integrated casing.

The rotor may attach to the rotatable portion of the casing or shroud via at least one separate connection members), such as spoke(s), bar(s), or the like. The rotor blades may be attached to the connection member, e.g. may be glued, welded, screwed, bolted, etc, thereto.

The shroud may surround or envelop the rotor assembly.

The rotor assembly may be attached to a shaft.

The second end of the rotor assembly may attach to the first end of the shaft.

The rotor assembly may be separate from the casing. The rotor assembly may be attached to the excavation apparatus via the shaft such that the rotor assembly and surrounding shroud may turn freely as a single unit relative to the casing. The rotatabie portion of the casing may comprise at least one cutting e!ement(s) and/or cutting tool(s) which may be provided on, connected to, or disposed upon the rotatable portion of the casing.

Alternatively or additionally, the at least one cutting element(s) and/or tool(s) may be attached, connected to, or disposed on the rotor and/or on at least one rotor blade(s). The rotor may comprise at least one attachment point(s), for example, clamp(s) or collet(s) or the like, to allow the attachment of the at least one cutting element(s) and/or tool(s) to the rotor. The attachment point(s) e.g. c!amp(s) or col!et(s) may comprise a suitable means for connecting the cutting element(s) and/or tool(s) such as those known in the art, e.g. a chuck.

The rotatable portion of the casing may comprise, may define, or may be a shroud. The rotatable portion may comprise at least one outer face and at least one inner face and may comprise at least one outer edge. The at least one cutting element(s) and/or tool(s) may be disposed on the outer face(s) and/or edge(s) of the rotatable portion. Alternatively or additionally, the at least one cutting element(s) may be disposed on the inner face(s) of the rotatable portion. Alternatively or additionally, the cutting element(s) and/or tool(s) may be connected, e.g. affixed, attached, fused, or bolted to at least one rotor blade(s).

The cutting element(s) and/or tool(s) may be provided integral with the rotatable portion and/or shroud and/or rotor and/or rotor biade(s).

The cutting eiement(s) and/or tool(s) may be removable, or may be fixedly attached to the rotatable portion and/or shroud and/or rotor and/or rotor biade(s).

The cutting element(s) and/or tool(s) may be used for machining a worksurface, seabed or other objects.

The cutting eiement(s) and/or tooi(s) may comprise, for example, at least one of drilling tool(s), milling tool(s), protrusion(s), tooth/teeth, cutting biade(s), abrasive surface(s), burr(s), groove(s), saw blade(s), or the like. The cutting tool(s) and/or element(s) may comprise an individual tool or element, and/or may comprise a plurality of cutting elements and/or tools, which may be disposed in groups, bands, lines or patterns, or the like, of cutting e!ement(s) and/or tool(s).

The cutting element(s) and/or tool(s) may be located on the tip of the shroud. The cutting element(s) and/or tool(s) may extend axially towards the first end of rotatable portion and/or away from the rotatabie portion. The cutting element(s) and/or tool(s) may extend axially from the first end of the rotatable portion and/or shroud and/or rotor and/or rotor blade(s), towards the second end. The cutting element(s) and/or tool(s) may be disposed, e.g circumferentially and/or axially, on the inner and/or outer face(s) of the shroud. The cutting e!ement(s) and/or tool(s) may form an annular blade(s), and/or may be disposed, e.g. radially and/or axially, at discrete iocation(s) around the annulus of the rotatable portion and/or shroud and/or rotor and/or rotor blade(s). By such provision, the cutting element(s) and/or tool(s) may form a concentric ring(s) of cutting element(s) and/or tool(s) on the inner and/or outer faces and/or tip of the shroud. The cutting element(s) and/or tooi(s) may vary in size or may be of the same size. The individual, e.g. concentric ring(s) of, cutting element(s) and/or tooi(s) may vary in, e.g. size, pitch, angle and/or may form a screw thread.

The cutting element(s) and/or tool(s) may attach directly to at least one rotor blade(s). In such case, the cutting ele ent(s) and/or tooi(s) may form and/or be integrated in the shroud. Alternatively or additionally, the cutting element(s) and/or tool(s) may replace or may define the shroud. Alternatively or additionally, a protruding section may extend, e.g. axially, from the rotor and/or rotor blade(s) to which the cutting element(s) and/or tool(s) may be integrated, or may be attached or connected. By such provision, a tip(s) or extreme end(s) of the cutting element(s) and/or tool(s) may be positioned away or distal from the excavation apparatus. It will be appreciated that varying the axial length of the protruding section will vary the distance of the tip(s) or extreme end(s) of the cutting eiement(s) and/or tool(s) from the excavation apparatus.

The cutting element(s) and/or tool(s) may vary in profile and may be, for example, rounded, triangular, rectangular or may be formed In any suitable shape or profile.

The cutting element(s) and/or tool(s) may be provided or disposed on, at or near a lower portion of the assembly, e.g., a lower end or first end of the rotatable portion or shroud, which in use, may be adjacent to, or may contact a work surface when the assembly is lowered towards the work surface. By such provision, the cutting eiement(s) and/or tooi(s) may aid cutting of a material at, on or near to the work surface and may protect the rotatable portion or shroud in the event of contact with the work surface, a seabed or other objects. By such provision, the rotatable portion of the casing, e.g. shroud, may further act or function as a cutting tool which may assist in cutting or excavating a surface, e.g. the seabed.

In use, in suction mode, the cutting element(s) and/or too!(s) on the rotatable portion and/or shroud and/or rotor may act to cut, pulverise, break or grind a material entrained in the fluid moving through the apparatus before reaching the rotor, thereby limiting an amount of large particles entering the assembly, helping to protect the internal components, in particular, the rotor blades, from impact by large particles.

In use, in blowing and/or jetting mode, the cutting element(s) and/or tool(s) on the rotatable portion and/or shroud and/or rotor may act to cut, pulverise, break or grind material on the worksurface and/or excavating surface, e.g. the worksurface, seabed, or other objects; and the jet of fluid may simultaneously and continuously displace loose material e.g. swarf, loose rock, silt, and dust, generated during machining.

A fluid passageway, e.g. at a first end thereof, may be defined between the outer surface of the rotor and the inside surface of the shroud.

The fluid passageway through the rotor assembly may be aligned with, and/or be in direct fluid communication with the fluid passageway through the casing. By such provision, a continuous fluid channel is defined through the excavation apparatus.

The rotor blades may be located within the fluid passageway through the rotor assembly.

The motor housing may have a first end provided near or facing towards the first end of the casing. The motor housing may have a second end provided near or facing towards the second end of the casing.

The motor housing may comprise or may be formed of two or more sections which may be connected or attached or welded by conventional means, or may be configured, formed or manufactured as a single and/or unitary component.

The first end of the motor housing may contain or may encase a bearing unit.

The second end of the motor housing may contain or may encase the motor.

The motor may be a mechanical motor.

The motor may be an electrical motor.

Advantageously, the motor may be a hydraulic motor. By such provision, the pump may provide higher torque than an electrical motor. Furthermore, hydraulic motors typically may not contain any electrical components and are therefore able to operate under water, without the requirement for waterproof sealing.

The motor may be located within a motor housing.

The motor housing may be located centrally within the casing and/or may share a common longitudinal axis as the casing.

The motor housing may have a generally circular cross-section.

The motor may be supplied with power via a conduit between the motor housing and the exterior of the casing.

The motor may drive the rotor assembly via the shaft.

The motor housing may encase, contain or support at least one bearing, bearing assembly or bearing unit.

The motor may be located away from the excavation apparatus, e.g. on the surface and may communicate with the excavation apparatus via the conduit. A bearing, bearing assembly or bearing unit and a motor may be contained within, and be encased by the motor housing.

The bearing, bearing assembly or bearing unit may comprise a number of individual bearings, or may comprise one bearing.

The bearing, bearing assembly or bearing unit may support the shaft.

A second end of the shaft, e.g. an end of the shaft facing towards the second end of the casing and/or opposite an end of the casing comprising the rotatable portion, may be driven by the motor.

A first end of the shaft, e.g., an end of the shaft facing towards the first end of the casing and/or towards the rotatable portion, may extend outside the first end of the motor housing.

The first end of the shaft may extend outside of the first end of the motor housing and/or may attach to the rotor assembly.

A cage, mesh or cover may be attached to the first end of the casing. By such provision, particulate and/or solid matter entrained in the fluid can be filtered, e.g. strained, sieved or sifted, helping to minimise the amount of particulate and/or solid matter entering the pump.

Advantageously, in the present arrangement, a self-contained rotor assembly may be connected to a portion of the casing in the form of a shroud which can be attached to a driven shaft without disassembly of the casing. Thus, the rotor assembly is not permanently encased by, or attached to, any part of the excavation apparatus other than the shaft. This allows the pump apparatus to be accessed for inspection, service, reparation, or replacement much more quickly and easily than is currently possible.

According to a second aspect of the present invention, there is provided a pump rotor assembly for use in an excavation apparatus,

wherein the pump rotor assembly is configured for moving fluid through a passageway of the excavation apparatus,

and wherein the rotor assembly is attached to a rotatable portion of a casing of the excavation apparatus.

A rotor of the pump rotor assembly may comprise one or more rotor blades, typically a plurality of rotor blades. In use, rotation of the rotor, e.g. rotor blades, may cause movement of fluid through the passageway.

The rotor assembly may comprise, e.g. may be formed unitary with, the rotatable portion of the casing. The rotatable portion may be tixedly or permanently attached to the at least one rotor blade, e.g. to a plurality of rotor blades, typically to the rotor blades. By such provision, rotation of the rotor, in use, causes rotation of the rotatable portion of the casing.

The rotor assembly may be fixed, or connected to, e.g. may be permanently attached, fixed or connected to, e.g. welded to, the rotatable portion of the casing.

By such arrangement, when removal of the rotor or portion thereof is required, for example due to the need for replacement, repair and/or maintenance, the rotor can be removed from the excavation apparatus without the need to remove or dismantle an outer casing thereof.

The excavation apparatus may be or may comprise an excavation apparatus according to the first aspect.

Features described above in respect of the apparatus according to the first aspect are equally applicable to the pump rotor assembly according the second aspect, and are not repeated here merely for reasons of brevity.

According to a third aspect of the invention, there is provided a method of moving fluid through an excavation apparatus, the method comprising:

rotating a pump rotor, wherein the pump rotor is configured to move a fluid through a passageway defined by a casing of the apparatus, the casing comprising a stationary portion and a rotatable portion, wherein, in use, rotation of the rotor causes rotation of the rotatable portion of the casing.

Preferably, the rotor may be attached to the rotatable portion of the casing. Thus, in use, the method may comprise rotating the rotatable portion of fhe casing.

The rotor may comprise at least one rotor blade.

The rotor, e.g. rotor blades, may be attached to the rotatable portion of the casing. By such provision, rotation of the rotor, in use, may cause rotation of the rotatable portion of the casing relative to the stationary portion of fhe casing.

In use, rotation of fhe rotor, e.g. rotor blades, causes movement of fluid through the passageway.

In blowing and/or jetting mode, the method may comprise ejecting or expelling a flow of fluid from a/the working end and/or directing the flow of fluid towards a/the work surface.

In blowing or jetting mode, the working end may comprise, may be or may define the second end. Thus, the method comprises moving fluid from the first end to the second end. Alternatively, e.g. is the direction of rotation of the motor is reversed, the working end may comprise, may be or may define the first end, and the method may comprise moving fluid from the second end to the first end.

In suction mode, the method may comprise drawing fluid into the apparatus through a/the working end and/or directing the flow of fluid away from a/the work surface. In suction mode, the working end may comprise, may be or may define the first end, and the method may comprise moving fluid from the first end to the second end. Alternatively, e.g. if the direction of the rotation of the motor is reversed, the working end may comprise, may be or may define the second end, and the method may comprise moving fluid from the second end to the first end.

The excavation apparatus may be or may comprise an excavation apparatus according to the first aspect.

According to a fourth aspect of the present invention, there is provided an excavation apparatus comprising:

a casing, defining a fluid passageway, the casing comprising a stationary portion and a rotatable portion;

wherein the rotatable portion of the casing comprises at least one cutting element(s) and/or cutting tool(s).

The at least one cutting element(s) and/or cutting tool(s) may be provided on connected to, or disposed upon the rotatable portion of the casing.

The excavation apparatus may further comprise a pump, configured for moving a fluid through the apparatus, for example, through the fluid passageway. The pump may comprise a rotor and at least one rotor b!ade(s) and the pump rotor may be connected to the rotatable portion of the casing, which may be connected via the at least one rotor b!ade(s).

The rotatable portion of the casing may comprise, may define, or may be a shroud. The rotatable portion may comprise at least one outer face and at least one inner face and may comprise at least one outer edge. The at least one cutting eiement(s) and/or tool(s) may be disposed on the outer face(s) and/or edge(s) of the rotatable portion. Alternatively or additionally, the at least one cutting element(s) may be disposed on the inner face(s) of the rotatable portion.

Alternatively or additionally, the rotatable portion and/or rotor may include, or be connected to, at least one attachment point, for example, clamp(s) or coliet(s) or the like, to allow the attachment of the at least one cutting element(s) and/or tool(s) to the rotatable portion and/or shroud and/or rotor. The cutting element(s) and/or tool(s) may be removable, or may be fixedly attached to the attachment point e.g. ciamp(s) or coliet(s) and/or rotatable portion and/or shroud and/or rotor. The cutting element(s) and/or tool(s) may be provided integral with the rotatable portion and/or shroud and/or rotor. The attachment point(s) e.g. clamp(s) or collet(s) may comprise a suitable means for connecting the cutting elements) and/or tool(s) as known in the art, e.g. a chuck.

The cutting eiement(s) and/or tooi(s) may comprise, for example, at least one of drilling tool(s), milling tool(s), protrusion(s), tooth/teeth, cutting biade(s), abrasive surface(s), burr(s), groove(s), saw blade(s), or the like. The cutting tool(s) and/or element(s) may comprise an individual tool or element, and/or may comprise a plurality of cutting elements and/or tools, which may be disposed in groups, bands, lines or patterns, or the like, of cutting elements and/or tools.

The cutting element(s) and/or tool(s) may be disposed on a lower portion of the assembly, e.g., a lower end or first end of the rotatable portion or shroud, which in use, may be adjacent to, or may contact a work surface when the assembly is lowered towards the work surface. By such provision, the cutting element(s) and/or tooi(s) may aid cutting of a material at, on or near to the work surface and may protect the rotatable portion or shroud in the event of contact with the work surface, a seabed or other objects. By such provision, the rotatable portion of the casing, e.g. shroud, may further act or function as a cutting tool which may assist in cutting or excavating a surface, e.g. the seabed.

In use, in suction mode, the cutting element(s) and/or tool(s) on the rotatable portion and/or shroud and/or rotor may act to cut, pulverise, break or grind a material entrained in the fluid moving through the apparatus before reaching the rotor, thereby limiting an amount of large particles entering the assembly, helping to protect the internal components, in particular, the rotor blades, from impact by large particles.

In use, in blowing and/or jetting mode, the cutting element(s) and/or tool(s) on the rotatable portion and/or shroud and/or rotor may act to cut, pulverise, break or grind material on the worksurface and/or excavating surface, e.g. the worksurface, seabed, or other objects; and the jet of fluid may simultaneously and continuously displace loose material, e.g. swarf, loose rock, silt, and dust, generated during machining.

According to a fifth aspect of the present invention, there is provided a method of moving fluid through an excavation apparatus, the method comprising:

rotating a rotatable portion of a casing of the apparatus, wherein the rotatable portion of the casing comprises at least one cutting element(s) and/or cutting tool(s). The method may comprise rotating a pump rotor, wherein the pump rotor is configured to move a fluid through a passageway defined by the casing of the apparatus, the casing comprising a stationary portion and the rotatable portion. The method may comprise rotating the pump rotor. In use, rotation of the rotor may cause rotation of the rotatable portion of the casing.

The method may comprise using the apparatus in suction mode. The method may comprise cutting into a surface, e.g. seabed. The method may comprise cutting, pulverising, breaking or grinding a material entrained in the fluid moving through the apparatus before reaching the rotor, e.g. due to the provision of the cutting element(s) and/or too!(s) on the rotatable portion and/or shroud and/or rotor. This may help to limit an amount of large particles entering the assembly, and/or help to protect the internal components, in particular, the rotor blades, from impact by large particles.

The method may comprise using the apparatus in blowing mode. The method may comprise cutting into a surface, e.g. seabed. The method may comprise cutting, pulverising, breaking or grinding material on the worksurface and/or excavating surface, e.g. the worksurface, seabed, or other objects; e.g. due to the provision of the cutting e!ement(s) and/or tool(s) on the rotatable portion and/or shroud and/or rotor. The method may comprise simultaneously and/or continuously displacing loose material, e.g. swarf, loose rock, silt, and dust, generated during machining, e.g. by the jet of fluid.

The excavation apparatus may be or may comprise an excavation apparatus according to the fourth aspect.

For the avoidance of doubt, any feature described in respect of any aspect of the invention may be applied to any other aspect of the invention, in any appropriate combination. For example, apparatus features may be applied to method features and vice versa.

Brief Description of the Drawings

The present invention will now be further described in detail and with reference to the figures in which:

FIG. 1 is a sectional and longitudinal view of an excavation apparatus embodying a rotor according to the prior art.

FIG. 2 is a sectional and longitudinal view of the pump system of the excavation apparatus of FIG. 1 with all other components omitted. FIG. 3 is a sectional and longitudinal view of an excavation apparatus according to a first embodiment of the present invention.

FIG. 4 is a sectional and longitudinal view of the pump system of the excavation apparatus of FIG. 3 with all other components omitted.

FIG. 5 shows the rotor assembly and shaft of the apparatus of FIG. 3, with ail other components omitted.

FIG. 6a shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which the cutting element(s) and/or tool(s) are of rectangular profile.

FIG. 6b shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which the cutting element(s) and/or tool(s) are of triangular profile.

FIG. 6c shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which the cutting elements) and/or too!(s) are of triangular profile and extend along the interior faces of the shroud.

FIG. 6d shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which the cutting element(s) and/or tool(s) are substantially rounded and extend along the interior and exterior faces of the shroud.

FIG. 7 shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which a collet is attached to the rotor which supports a cutting element(s) and/or tool(s).

FIG. 8a shows the rotor assembly and shaft of FIG. 5 according to another embodiment of the present invention in which the shroud is defined by a protruding section which comprises cutting e!ement(s) and/or tool(s) which connect directly to the rotor.

FIGs. 8b and 8c show a sectional and longitudinal view, and a front elevation of the rotor assembly of FIG. 8a showing all other components of the excavation apparatus of FIG. 3. However, all other reference numerals have been omitted for clarity of the drawing.

Detailed Description of the Drawings

FIGs. 1 and 2 show an excavation apparatus embodying a rotor according to the prior art. The excavation apparatus 1 comprises a pump 2 and a casing 21 . The casing 21 is generally cylindrical about a longitudinal axis (A) and has a first end 41 , and distal second end 42 opposite the first end 41. A diffuser 22 is attached to the first end 41 of the casing 21 and a nozzle 23 is attached to the second end 42 of the casing 21. The pump 2 is generally cylindrical and is contained within the casing 21. The pump 2 comprises a rotor assembly 3 and a motor housing 13. The rotor assembly 3 comprises a rotor 4, to which a number of rotor blades 5 are rigidly attached. The motor housing 13 comprises a motor 12, bearing unit 1 1 and shaft 10. The rotor 4 is rigidly attached to a first end 10a of a shaft 10, which is provided at or near the first end 41 of the casing 21 , which is supported by the bearing unit 1 1 and driven by the motor 12. The motor 12, shaft 10 and bearing unit 1 1 are contained within the motor housing 13. The first end 10a of the shaft 10 extends outside the motor housing 13. The rotor assembly 3 and motor housing 13 are centrally located within an outer casing 21 along axis (A). The rotor assembly 3 is free to rotate within the diffuser 22. Very fine tolerances exist between the outer edges of the rotor blades 5 and the inner surface of the diffuser 22 to ensure optimum efficiency, whilst maintaining the structural integrity of the apparatus. The motor housing 13 comprises two regions, a generally parallel sided region 13a at its first end, which is provided at or near the first end 41 of the casing 21 , and a second end, which is provided at or near the second end 42 of the casing 21 , which is tapered 13b such that it forms a generally rounded bullet shape.

The outer casing 21 is generally cylindrical and comprises two ends; a first end region 21 a which surrounds the first end of the motor housing 13a which contains the bearing unit 1 1 , and a second end region 21 b which surrounds the tapered second end of the motor housing 13b which contains the motor 12. A diffuser 22 is attached to the first end 41 of the casing 21 a. The diffuser has a first end distal to the casing 21 , and a second end, immediately adjacent and/or abutting the casing 21. The diameter of the first end of the diffuser 22 is less than that of the casing 21 a. The diffuser 22 further comprises a throat 22a located between the first end and second end of the diffuser 22, and an outer lip 22b, located at the first end 41 of the casing 21 , which diverges radially outwards away from the central axis at the first end of the diffuser 22, such that the diameter at the outer lip 22b is larger than that at the throat 22a, such that a converging-diverging diffuser is formed. Preferably the throat 22a is located between the outer lip 22b and the rotor blades 5 such that the rotor blades 5 are located In the diverging section of the diffuser 22.

The nozzle 23 is attached to the second end 42 of the casing 21 b and the nozzle 23 comprises two sections 23a, 23b which are disposed at varying angles to allow for varying levels of convergence of the nozzle, and thus affect the exiting fluid jet.

The motor 12 receives power through a conduit 14 which extends to the outside of the casing 21 .

The casing 21 , diffuser 22 and nozzle 23 may be formed of separate components which are attached together with the use of a fastening means such as nuts and bolts. The rotor assembly 3 and motor housing 13 are located along the same axis (A), which are centrally located within the casing 21 such that an annular channel 24 is defined between the rotor assembly 3 and the casing 21 ; and an annular channel 25 is defined between the motor housing 13 the outer casing 21. The annular channels 24, 25 run along the longitudinal axis (A) of the excavation apparatus 1 and are defined between the outer surfaces of the rotor 4, motor housing 13 and the interior surfaces of the casing 21.

A number of baffles 15 are disposed within the annular channel 25 between the outside surface of the motor housing 13 and the inside surface of the casing 21. These may be disposed in one of or in a combination of the longitudinal, transverse or angled planes. The baffles 15 run along axis (A), splitting the annular channel 25 into a number of smaller parallel channels in order to impede the rotational velocity of the flow about the axis A, thus creating a more laminar flow.

A plenum 20 is defined between the outer surface of the tapered end of the motor housing 13b, the inside surface of the casing 21 and the inside surface of the nozzle 23.

A cage, mesh or cover 30 is attached to the first end 41 of the casing 21 which can act to filter the entrained fluid and help to prevent particulate matter prior from entering the pump 2.

In use, the rotor assembly rotates and entrains fluid from the surrounding area and transfers it to the diffuser, where it is directed with the use of the baffles, to the nozzle where it exits as a high velocity laminar fluid jet with low swirling velocity to generate a high impulse fluid suitable for use in seabed clearing operations.

FiGs. 3 to 5 show an apparatus 101 according to a first embodiment of the present invention. The apparatus 101 is generally similar to the apparatus 1 of Figure 1 , like parts being denoted by like numerals, but incremented by Ί00’.

In this embodiment, the casing 121 comprises at least two portions, a stationary portion 121 and a rotatable portion 106. The rotatable portion is located at the first end 141 of the excavation apparatus 101 and the stationary portion is located at the second end 142. The rotatable portion 106 may be rotatably moveable relative to the stationary portion of the casing 121 . The rotatable portion 106 is separated from the stationary portion of the casing 121 at a separation location 107 by a gap. The rotatable portion 106 may be in the form of a shroud which may be rigidly attached to one or more rotor blades 105 to form an integrated casing which is adjacent to, but separate from the stationary portion of the casing 121 .

This is achieved by segmenting the diffuser 122 into two sections; a truncated diffuser 108 and a shroud 106. The truncated diffuser 108 and shroud 106 are separated at location 107 by a gap. The truncated diffuser 108 may be separate to the casing 121 a and attached via a fastening means, but in this embodiment the casing 121 a and the truncated diffuser 108 are manufactured as a single unit.

The shroud 106 further comprises a throat 106a located between its first and second ends and an outer lip 106b which diverges radially outwards away from the centra! axis at the first end of the shroud 106, such that the diameter at the outer lip 106b is larger than that at the throat 106a, such that a converging-diverging shroud is formed. Preferably the throat 106a is located between the outer lip 106b and the rotor blades 105 such that the rotor blades 105 are located in the diverging section of the shroud 106.

The truncated diffuser 108 and rotor assembly 103 follow the same shape profile of the unmodified diffuser 22 of FIG. 1 so that the surfaces of the truncated diffuser 108 and the shroud 106 are flush. In this way, the diverging annular channel 124 surrounding the rotor 104 aligns with, and creates a continuous fluid channel with, the generally parallel sided channel 125 surrounding the motor housing 1 13, such that ail channels are in direct fluid communication with each other.

The shroud 106 is rigidly attached to at least one of the rotor blades 105, such that the rotor assembly 103 comprises the rotor 104, rotor blades 105 and the shroud 106, all of which form a single unit and rotate together in use. This allows the entire rotor assembly 103 comprising the rotor 104, rotor blades 105 and shroud 106, to be removed without the need to disassemble the casing 121 of the excavation apparatus 101.

The pump rotor assembly 103 may not rotate within the casing 121 , but rather the rotor assembly 103 is enveloped with an integrated rotatable portion of the casing in the form of a surrounding shroud 106, such that the rotor assembly 103 and the rotatable portion of the casing 106 turn freely together as a single unit in the working fluid relative to the adjacent stationary casing 121 and motor housing 1 13. Since the enveloping rotor shroud is rigidly attached to the rotor blades, no such fine tolerances exist in this embodiment, easing manufacturing processes.

In this embodiment, in blowing or jetting mode, the working end is, comprises or is defined by the second end 142, that is, the end of the apparatus 101 near the nozzle 123. By such provision, a flow of fluid moves from the first end 141 (near the rotatable shroud 106) to the second end 142 (near the nozzle 123). By the provision of cage, mesh or cover 130 attached to the first end 141 , some or ail solid or particulate matter entrained by the fluid can be prevented from entering the apparatus 101 . It will be understood that, in another embodiment, for example if the direction of the rotor is reversed, in blowing or jetting mode, the working end may comprise or may be defined by the first end 141 , that is, the end of the apparatus 101 near the rotatable shroud 106

If the apparatus 101 is used in suction mode, the working end may be defined by the first end 141 , that is, the end of the apparatus 101 near the shroud 106. By such provision, a flow of fluid moves from the first end 141 (near the rotatable shroud 106) to the second end 142 (near the nozzle 123) By the provision of cage, mesh or cover 130 attached to the first end 141 , some or all solid or particulate matter entrained by the fluid can be prevented from entering the apparatus 101. Alternatively, for example If the direction of the rotor is reversed, in suction mode, the working end may comprise or may be defined by the second end 142, that is, the end of the apparatus 101 near the nozzle

FiGs. 6a to Sd show an apparatus 101 according to further embodiments of the present invention. In these embodiments, cutting element(s) and/or tool(s) 206a to 206d are disposed on the shroud 106. The cutting element(s) and/or tool(s) may vary in profile and may be, for example, rounded, triangular, rectangular or may be formed in any shape profile. FiG, 6a shows an embodiment in which the cutting element(s) and/or tool(s) are of rectangular profile 206a. FIG. 6b and 6c shows an embodiment in which the cutting eiement(s) and/or tool(s) are of triangular profile 206b, 206c. FIG. 6d shows an embodiment in which a number of cutting elements and/or tools are disposed on the interior and exterior faces of the shroud This embodiment shows substantially rounded cutting element(s) and/or tool(s) 206d, however, it will be appreciated that the cutting element(s) and/or tool(s) may be of any suitable shape or profile that allows the cutting elements and/or tools 206a to 206d to assist the apparatus in cutting into a worksurface, e.g seabed, during rotation of the shroud 106. The cutting elements and/or tools 206a to 206d may also provide protection and/or may reduce damage to the apparatus, e.g. shroud 106 during operation, e.g. during contact with the seabed.

FiG. 7 shows an apparatus 101 according to another embodiment of the present invention. In this embodiment, a shaft 208 is attached or connected to rotor 104. The shaft 208 extends along axis (A), towards the first end of the apparatus 101 and through the shroud 106. At a first end of the shaft 208 is a collet 207, which allows the attachment of at least one cutting element(s) and/or tool(s) 206e. The collet 207 may comprise a chuck (not shown) as known in the art for the attachment of the cutting e!ement(s) and/or tool(s) 206e. it will be appreciated that the cutting element(s) and/or too!(s) 206e may be of any shape or profile, for example similar to those shown in FIG. 6a to 6d.

It will be appreciated that connecting the cutting e!ement(s) and/or tool(s) 2G6e to c!amp(s) or co!let(s) 207 permits the cutting element(s) and/or tool(s) 206e to be removed or replaced quickly and easily allowing it to be customised for a specific application.

FiG. 8a, 8b and 8c show an apparatus 101 according to another embodiment of the present invention. FIG. 8a shows a side elevation of the shaft and rotor assembly; and FIG. 8b and FIG. 8c show a sectional and longitudinal view, and a front elevation of the complete excavation apparatus of FIG. 3. in this embodiment the shroud is defined by a protruding section which comprises cutting element(s) and/or tooi(s) 2G6f which connect directly to at least one rotor blade(s) 105. The cutting elements) and/or tool(s) 206f comprise a number of angled teeth which extend from the rotor assembly along axis (A). The angled teeth are radially disposed on the rotor assembly, connected to the rotor 104 via the rotor blade(s) 105. All other reference numerals have been omitted for clarity of the drawing.

In embodiments comprising cutting element(s) and/or tool(s) 206a to 206f, as shown in FIG. 6a to 6d, FIG. 7 and FIGs. 8a-8c; in use, in suction mode, as the rotor 104 rotates, the cutting element(s) and/or tool(s) 206a to 206f also rotate and may act to cut, pulverise, break or grind a material entrained in the fluid moving through the apparatus 101 before reaching the rotor 104, thereby limiting an amount of large particles entering the assembly, helping to protect the internal components, in particular, the rotor blades 105, from impact by large particles. Additionally or alternatively, the cutting element(s) and/or tool(s) 206a to 206f can be used in contact with the worksurface, seabed or other objects (not shown) to cut, pulverise, break or grind a material to further work and/or excavate the worksurface. In these embodiments, in use, in blowing and/or jetting mode, the cutting element(s) and/or tool(s) 206a to 206f on the rotatable portion and/or shroud 106 and/or rotor 104 and/or rotor blades 105 may act to cut, pulverise, break or grind material on the worksurface and/or excavating surface, e.g. the worksurface, seabed, or other objects; and the jet of fluid may simultaneously and continuously displace loose material, e.g. swarf, loose rock, silt, and dust, generated during machining. In these embodiments, in use, in suction mode, the cutting element(s) and/or tool(s) 206a to 2G6f on the rotatable portion and/or shroud 106 and/or rotor 104 and/or rotor blades 105 may act to cut, pulverise, break or grind material on the worksurface and/or excavating surface, e.g. the worksurface, seabed, or other objects; and the suction of fluid may simultaneously and continuously draw the loose material, e.g. swarf, loose rock, silt, and dust, generated during machining through the device, where it exits from the second end 142 of the excavation apparatus.

By such provision, the efficiency and efficacy of the excavation process is increased since a cutting action from the cutting element(s) and/or tool(s) 206a to 2G6f is imposed on the worksurface, in addition to the high pressure fluid flow induced by the rotor assembly 103.

The cutting eiement(s) and/or tool(s) 206a to 206f can be used, and provide the aforementioned benefits in both blowing or jetting mode; and suction mode.

It can be appreciated that the cutting element(s) and/or tool(s) 206a to 206f may further protect the shroud 106 since in the event of contact with the worksurface, the contact between the shroud 106 and the worksurface is minimised or prevented, thereby increasing the longevity of the device 101. A person of skill will also appreciate that this further means that the shroud 106 will not need to be designed to resist extended contact with the seabed, meaning that very high strength and highly specialised materials or hardened steels are not be required for the construction of the apparatus 101 , reducing the weight and cost of the apparatus 101.

It will be appreciated that any of the types of cutting element(s) and/or tooi(s) 206a to 206f; and/or shaft 208 and/or collet 207 shown in the aforementioned embodiments and in FIG. 6a to 6d, FIG. 7 and FIGs. 8a-8c may be combined with and/or used in conjunction with each other.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as described herein without departing from the scope of the present invention. The present embodiments are therefore to be considered for illustrative purposes and are not restrictive, and are not limited to the extent of that described in the embodiment.