AU2021245113A1

AU2021245113A1 - A modular dust extraction unit

Info

Publication number: AU2021245113A1
Application number: AU2021245113A
Authority: AU
Inventors: Michael Paul MCLEAN
Original assignee: Dowsing Nsw Pty Ltd
Current assignee: Dowsing Nsw Pty Ltd
Priority date: 2021-04-09
Filing date: 2021-10-05
Publication date: 2022-10-27

Abstract

A modular dust extraction unit, comprising: - a housing configured for permanent or removable mounting 5 to a milling machine; - a suction inlet into the housing connectable via at least one duct to at least one designated dust collection location of the milling machine; - a fan unit arranged for generating negative pressure 10 within the housing to induce a dust particle containing air stream at the designated dust collection location through the suction inlet; - a filter or precipitator unit at or within the housing and in communication with the suction inlet, the filter or 15 precipitator unit configured to remove dust particles from the dust particle containing air stream passing through it; - a container unit at or within the housing and in communication with the filter or precipitator unit to 20 receive dust particles removed by the filter or precipitator unit; - a dispensing unit at the housing in communication with the container unit and arranged for selective removal from the container unit of dust particles accumulated therein; 25 and - a filtered air outlet in communication with the fan unit and filter or precipitator unit and configured to discharge into the surroundings a filtered air stream from which dust particles has been removed. 18130243_1 (GHMatters) P115556.AU.1 5/10/21

Description

A MODULAR DUST EXTRACTION UNIT

Field of the Invention The present invention relates generally to dust suppression equipment.

Specifically, although by no means exclusively, the invention relates to a modular dust extraction unit for an excavation machine, such as a surface milling machine.

The present invention also relates to a surface milling machine comprising a modular dust extraction unit.

Background of the Invention Excavation machines are used for breaking and removing rocks from the earth's surface.

Surface milling machines are a type of excavation machine that breaks a ground surface into smaller pieces and then removes the smaller pieces away from the surface. Surface milling machines are typically used when resurfacing roads.

A surface milling machine generally comprises: a chassis; a power plant, such as a diesel engine; operator's platform; tracks or wheels; a hydraulic levelling system mounted to enable vertical movement of the machine; a milling drum with ground engaging tools for breaking a ground surface; and a material transfer system including conveyors for removal of the excavated material from the ground surface.

In use, the milling drum of the surface milling machine rotates causing the ground engaging tools to impact the surface which breaks-up the ground surface material. The material is then moved onto the conveyor system for transport away from the machine.

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A problem with all excavating machines is that breaking and removing rocks from the earth's surface generates fines - small particles of rock that are capable of being suspended in the air, also known as dust - in areas where the material is excavated or transferred. The dust particles are then transferred into the surrounding atmosphere and become uncontained from the machine during material transfer and excavation. Once the uncontained material is in the atmosphere around the machine, it poses risk for site contamination and environmental damage particularly in enclosed spaces, such as built-up areas, tunnelling and where sensitive environmental conditions are present. Furthermore, inhalation of dust is harmful and therefore exposure to dust needs to be mitigated to meet occupational health and safety regulations.

Dedicated dust removal systems are used to suppress and/or remove dust. One such system involves spraying high pressure water (> 50 bar) to add a fine atomized mist to the air. The mist captures the dust particles which then drop to the ground. A problem with this system is that high pressure water requires a high amount of power a source of and access to water is required, and additional cleaning-up of slurry from surfaces where the wet dust particles settle.

Australian patent 2012242630 discloses a system for capturing dust generated by a cutting drum of a surface mining machine. The system comprises a shroud for partially covering the cutting drum, thereby defining a local dust extraction volume, and a means for producing a vacuum to draw dust laden air through a dust extraction conduit that has a plurality of spaced-apart openings and that is located between the shroud and the cutting drum, and from this conduit through an air cleaning/filtering unit carried at the shroud.

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Australian patent 2017101033 discloses a self-propelled (tracked) mobile dust extraction device, having a support frame with an inlet housing having suction inlets, a filter housing with at least one air filter connected to the inlet housing and a fan assembly mounted thereto for drawing polluted air through the inlets into the inlet housing and from there through the filter housing. A hopper is located beneath both the inlet housing and the filter housing for receiving heavier dust particles from the inlet housing and finer dust particles collected at the filter housing. Dust particles collected in the hopper are funneled down to an auger conveyor arranged to discharge the particles through a port with a rotary valve configured to enable passage without air being drawn in reverse flow into the auger. The mobile dust extraction device suction inlets are connected to ducts which run to a dust generating source such as a piece of earthmoving machinery that operates independently of the tracked dust extraction device. One disadvantage is that in the absence of a dedicated pneumatic conveyor system on the earthmoving machinery to supply the dust-laden air stream through the ducts connected to the inlets of the extraction unit, the latter's fan assembly needs to have specifications and be dimensioned to generate large enough suction head (under-pressure) to accommodate long conveying distances between the mobile dust extraction device and the independent earth moving device. Such will have increased power demands and make the fan unit heavy.

It is desirable to provide a modular dust extraction unit that improves at least one of the above disadvantages or at least provides a useful alternative to known dust extraction devices.

Summary of the Invention The invention provides a modular dust extraction unit,

18130229_1 (GHMatters) P115556.AU.1 5/10/21 comprising a housing configured for permanent or removable mounting to a ground milling machine, excavator or similar self-propelled vehicular or drawn machine which in operation generates excavation material and dust during operation. Such machine will be simpliciter referred to as milling machine herein below and in the appended claims. The apparatus further comprises a suction inlet into the housing connectable via at least one duct to at least one designated dust collection location of the milling machine; a fan unit arranged for generating negative pressure within the housing to induce a dust particle containing air stream at the designated dust collection location through the suction inlet; a filter or precipitator unit at or within the housing and in communication with the suction inlet, the filter or precipitator unit configured to remove dust particles from the dust particle containing air stream passing through it; a container unit at or within the housing and in communication with the filter or precipitator unit to receive dust particles removed by the filter or precipitator unit; a dispensing unit at the housing in communication with the container unit and arranged for selective removal of precipitated dust particles from the container unit; and a filtered air outlet in communication with the fan unit and filter or precipitator unit to discharge a filtered air stream from which the precipitated dust has been removed into the surroundings.

The modular dust extraction unit according to the present invention provides the advantage that it can be retrofitted on or temporarily fitted to milling machines when used in operational environments where suppression of dust in the surrounds of the milling machine is particularly important, such as in confined spaces like tunnels, airports or where areas are environmentally sensitive to dust particulate pollution. Installation of the modular dust extraction unit on the milling machine

18130229_1 (GHMatters) P115556.AU.1 5/10/21 provides a significant reduction in environmental dust produced by the milling operation, enabling "dustless milling".

The modular dust extraction unit can be mounted and secured distal from the actual dust generation and collection locations at a location of the milling machine that is more easily accessible for servicing and maintenance. In particular, the mounting location will be selected such that the milling machine need not interrupt its milling / excavation operation in order to enable removal of dust collected at the modular dust extraction unit's dust particles receiving container unit. The modular dust extraction unit can also be removed for servicing or replacement, as and when required.

Most dust extraction systems known in the art, for example Australian Patent 2017101033, are carried by / integrated in a separate vehicle to the milling machine. This presents a problem when manoeuvring the milling machine during milling operations, requiring extra attention by two independent operators to avoid collision damage between the two vehicular machines during positioning, and/or requiring the installation of expensive collision avoidance / movement coordination systems on both machines. The modular dust extraction unit according to the present invention addresses this issue.

Relevantly also, the modular arrangement allows for use of a single modular dust extraction unit to remove dust from various locations at the milling machine where dust is generated, such as the actual ground milling location and locations along the typically used open-bed conveyor(s) that transport excavated material away from the milling location to a conveyor discharge point which may be at the end of a transport and discharge boom at another end of the milling machine.

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In one embodiment, the fan unit is externally mounted to the housing. The fan unit may hereby be mounted in removable manner to a top portion of the housing. This makes the fan unit more accessible for servicing and maintenance.

In one embodiment, the dispensing unit is externally mounted to the housing below the container unit, in particular to a bottom portion the housing. This arrangement facilitates gravitational collection and regular disposal of dust particles that accumulate in the container unit, in particular in embodiments wherein the container unit is configured hopper-like or comprises a funnel like structure leading towards the discharge unit. Here again, such arrangement is chosen for ease of access for servicing and maintenance.

A particularly compact modular arrangement can be achieved wherein one or both the filter unit and container is/are housed within the housing of the modular dust extraction unit.

In one embodiment, the dispensing unit comprises a valve, in particular a rotational shutter valve that is operated either automatically or manually when disposal of accumulated dust particles is desired. Additionally, an auger can be provided to assist in transfer of dust particles from the container unit towards the location of the dispensing unit which could also comprise a metering wheel.

In a preferred embodiment, the filter unit or precipitator unit will contain a number of discrete (individual) air filtering or dust particle precipitator structures, as the case may be, configured for individual removal (for cleaning and re-installation) or replacement when cleaning

18130229_1 (GHMatters) P115556.AU.1 5/10/21 of the filter / precipitator unit is required. The number of filter / precipitator structures will depend on the dust removal specification, i.e. amount of allowable dust particles present in a given volume of discharged air stream after filtration /precipitation, as well as the specific type of filter /precipitator structure employed, amongst others. In one embodiment using an air filtering unit (as compared to a dust precipitator unit), the air filtering unit may contain between four and ten air filters. By providing individually removable and/or individually replaceable air filter structures, the cost of servicing and downtime can be significantly reduced.

In an advantageous embodiment, the fan unit is configured to be powered by a power supply device of the dust generating machine, for example, electrically, pneumatically or hydraulically. This negates the need for a separate source of power which may otherwise lead to a separate potential point of failure.

The dispenser unit may also be arranged to be operated using actuator facilities present at the dust generating machine. For example, the dispenser unit may have its own electric motor to operate the dispenser's valve, connected to an electricity generator or battery of the milling machine, or include a hydraulically driven valve switch that can be coupled to a hydraulic system of the milling machine.

In one embodiment, the filtered air outlet comprises a louvered vent configured to prevent backflow of air which would otherwise reduce the efficiency of the fan unit in generating an adequate negative pressure within the housing unit and in particular at the inlet thereof which connects to the suction duct.

In another aspect, the present invention provides a

18130229_1 (GHMatters) P115556.AU.1 5/10/21 milling machine having a modular dust extraction unit as previously described mounted to a support structure of the milling machine, the milling machine having a ground engaging tool for breaking a ground surface into excavated material and a material transfer system including a conveyor for removal of the excavated material away from the ground surface towards a conveyor discharge location at the milling machine, wherein the modular dust extraction unit is fixedly or removably mounted to the support structure of the milling machine, wherein at least one dust particle removal duct is connected in fluid communication with the suction inlet of the housing unit of the modular dust extraction unit, and wherein one or more dust extraction hoods are mounted on the milling machine in proximity of one or more of the ground engaging tool and at least one selected location along a path of the conveyor, in particular over the conveyor discharge location, the dust extraction hood(s) connected to a respective inlet(s) at the dust particle removal duct such as to provide fluid communication between the suction inlet at the housing unit and the extraction hood(s)

In yet another aspect, the present invention provides a method of reducing air-borne dust particles about and generated during operation of a milling machine that comprises a ground engaging tool for breaking a ground surface into excavated material, the milling machine having a material transfer system including a conveyor for transporting of the excavated material away from the ground surface towards a conveyor discharge location at the milling machine, including the steps of: providing a modular dust extraction unit as described in any one of the embodiments mentioned above; securing the dust extraction unit housing to a support structure of the milling machine; providing a dust particle removal duct and connecting same in fluid communication with the suction inlet of the housing unit; locating respective

18130229_1 (GHMatters) P115556.AU.1 5/10/21 dust extraction hoods in proximity of one or more of the ground engaging tool and at least one selected location along a path of the conveyor, in particular over the conveyor discharge location; connecting the dust extraction hoods to one or more inlets at the dust particle removal duct such as to provide fluid communication between the suction inlet at the housing unit and the extraction hoods; and operating the modular dust extraction unit during the breaking of the ground surface and/or discharging of the excavated material from the conveyor discharge location.

During operation of the modular dust extraction unit, air borne dust particles generated by the ground engaging tool (milling drum or any similar ground milling or excavating / breaking implement the milling machine may employ) can be removed effectively already at that location.

Furthermore, dust particles are generally also generated when discharging the excavated material from the conveyor discharge location into a vessel which receives the excavated material for subsequent disposal. To this end, many ground milling machines incorporate a boom structure that protrudes away from one end of the milling machine to enable excavation material to be transported for dumping into the tray of a tipper truck located in proximity of the milling machine. It is particularly advantageous to locate a dust extractor hood (or similar structure) at the boom end such that dust generated in the dumping process can be suctioned-up into an air-stream generated by the fan unit of the modular dust extraction unit.

Other features and aspects of the invention will become apparent to the skilled person from the following description of a preferred embodiment of the modular dust extraction unit of the present invention provided with reference to the accompanying drawings.

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Brief Description of the Drawings

Figure 1 is a front perspective view of a modular dust extraction unit according to an embodiment of the present invention;

Figure 2 is a rear perspective view of the modular dust extraction unit shown in Figure 1;

Figure 3 is a rear schematic view of the modular dust extraction unit shown in Figure 1, in which the dashed lines illustrate internal components;

Figure 4 is a top schematic view of the modular dust extraction unit shown in Figure 1, in which the dashed lines illustrate internal components;

Figure 5 is a side schematic view of the modular dust extraction unit shown in Figure 1, in which the dashed lines illustrate internal components;

Figure 6 is an exploded schematic view of the housing of the modular dust extraction unit according to another embodiment of the present invention;

Figure 7 is a rear perspective view of a surface milling machine and modular dust extraction unit according to another embodiment of the present invention;

Figure 8 is a side view of the surface milling machine and modular dust extraction unit shown in Figure 7;

Figure 9A is a side view of a dust collecting hood for the surface milling machine and modular dust extraction unit shown in Figure 7;

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Figure 9B is a side schematic view of the dust collecting hood shown in Figure 9A; and

Figure 9C is a front schematic view of the dust collecting hood shown in Figure 9A.

Detailed Description of Specific Embodiments

Figures 1 to 5 show an embodiment of the modular dust extraction unit 10 according to the present invention.

The modular dust extraction unit 10 comprises a housing 12 configured for permanent or removable mounting to a ground milling or excavating machine, such as a surface milling machine / road planer.

The housing 12 has at least one suction inlet 14a, 14b into the housing 12 connectable via ducts to at least one designated dust collection location of the milling machine.

The modular dust extraction unit 10 further comprises a fan unit 16 arranged for generating negative pressure within a cavity defined within or by the walls of housing 12, to induce a dust particle containing air stream at the designated dust collection location through the suction inlet 14a, 14b.

A filter unit 18 (as shown in Figure 4) is located at or within the housing 12 and in communication with the suction inlet 14a, 14b. The filter unit 18 is configured to remove dust particles from the dust particle containing air stream passing through the filter unit 18.

The modular dust extraction unit 10 also comprises a container section or unit within or at the housing 12 and in communication with the filter unit 18 to receive dust

18130229_1 (GHMatters) P115556.AU.1 5/10/21 particles removed by the filter unit 18 from the air stream passing through the filter structures of unit 18.

A dispensing unit 20 is located at the housing 12 in communication with the container unit and is arranged for selective removal of dust particles from the container unit.

Finally, a filtered air outlet 22 is in communication with the fan unit 16 and filter unit 18 to discharge a filtered air stream, from which the dust particles have been removed, into the ambient surroundings.

The housing 12 comprises an upper box portion 12a connected to a lower hopper portion 12b. The upper box portion 12a and lower hopper portion 12b are hollow and together define the container unit for receiving dust particles from and removed by the filter unit 18. The housing 12 has a longitudinal axis X-X, as shown in Figures 3 and 5.

The box portion 12a has five walls (upper, front, rear, left-side and right-side walls) that together define a single-side open-ended box.

The hopper portion 12b has four inclined walls (front, rear, left-side and right-side walls) that taper towards the lower end of the hopper portion 12b. The front wall and rear wall are inclined at an angle of preferably around 47 degrees relative to a horizontal plane extending perpendicular to the longitudinal axis X-X of the housing 12. The left-side wall and right-side wall are inclined at an angle of between 39 and 40 degrees relative to the horizontal plane extending perpendicular to the longitudinal axis X-X.

The hopper portion 12b has an upper opening and a lower

18130229_1 (GHMatters) P115556.AU.1 5/10/21 opening, with the upper opening having a larger cross sectional area than the lower opening, when viewed in plan. The upper opening of the hopper portion 12b has the same cross-sectional area as the cross-sectional area of the box portion 12a, when viewed in plan.

The box portion 12a and the hopper portion 12b are assembled together in a direction along the longitudinal axis X-X such that the open end of the box portion 12a communicates with the upper opening of the hopper portion 12b. The box portion 12a and hopper portion 12b are secured to each other via a flange connection. In this regard, the box portion 12a and the hopper portion 12b both have rim flanges, with holes located therein, that extend around their perimeters. The flanges are mated together to align the corresponding holes in the respective flanges. Fasteners, such as threaded bolts, can then be inserted through the aligned holes. Nuts are threaded onto the threaded bolts to secure the box portion 12a to the hopper portion 12b in removable manner. A sealing element can be disposed between the facing rims. Once assembled together, the box portion 12a and the hopper portion 12b define an enclosed space for receiving dust particles from the filter unit 18, i.e. the container unit.

As noted, the housing 12 comprises two suction inlets 14a, 14b that are located on the right-side wall and left-side wall of the box portion 12a, respectively. The suction inlets 14a, 14b are circular and have a diameter of 400 mm. The suction inlets 14a, 14b further include a rim that projects 78.0mm away from the respective right-side wall and left-side wall. The rims provide attachment surfaces for securing ducts to opposing sides of the housing 12. A hose clamp can be used to secure the ducts to the rim.

The housing 12 further comprises an upper opening that is

18130229_1 (GHMatters) P115556.AU.1 5/10/21 located on the upper wall of the box portion 12a. The upper opening is circular and has a diameter of between 600 to 700mm in the illustrated embodiment.

The modular dust extraction unit 10 comprises a frame mounted to the front wall of the box portion 12a that is attached to an external surface of the ground milling machine. The frame comprises a four-point linkage system and a hydraulic ram that provides height adjustability of the modular dust extraction unit 10 relative to the ground. This allows the modular dust extraction unit 10 to be raised or lowered to assist skilled workers in servicing the modular dust extraction unit 10 and/or the ground milling machine. It is also envisaged that the modular dust extraction unit 10 may be sideways adjustable relative to the ground milling machine. For example, the fame may have rollers that are slidably engaged with a track that is mounted to an external surface of the ground milling machine. However, it is also envisaged that any suitable height or sideways adjustment mechanism known in the art may be employed.

The fan unit 16 comprises a conch shaped fan cowling. The fan cowling is defined by an upper wall and lower wall, in a parallel spaced apart arrangement, connected to each other via a perimeter wall to define an internal cavity. The perimeter wall is spirally curved about an axis to define the conch shape of the fan cowling. The fan cowling has a series of openings: a first opening, a circular orifice, positioned axially on the lower wall; a second opening, a circular orifice, positioned axially on the upper wall; and a third opening, a rectangular orifice, positioned on the perimeter wall perpendicular to the axis.

The fan unit 16 attaches to the upper wall of the housing 12 such that the first opening is aligned with the upper

18130229_1 (GHMatters) P115556.AU.1 5/10/21 opening of the housing 12. Preferably, the lower wall of the fan unit 16 is attached to the upper wall of the housing 12 by any conventional releasable means, such as bolting. However, it is also envisaged that the fan unit 16 may be attached to the upper wall of the housing 12 by permanent means, such as riveting or welding.

The fan unit 16 houses a rotating fan element. The fan element comprises a pair of axially spaced discs, one of the discs having a central opening, a pair of blades connect the parallel discs so as to form a radially extending slot that extends to the central opening. In use, the fan element rotates axially within the internal cavity of the fan cowling and forces air through the central opening and out through the radially extending slot. As the fan element rotates it produce a differential pressure across the inlet and outlet of the fan unit 16. This differential pressure produces a negative pressure which induces a flow of air passing through the filter unit 18 and the fan unit 16. The flow of air enters the fan unit 16 via the first opening and exits the fan unit 16 via the third opening, also known as the air outlet 22.

In one exemplary embodiment, the fan unit has the following specification: Differential pressure : 0.80 kPa @ 1420 RPM Air flowrate : +/- 3.5 m 3 /s Air velocity : 130-150 m/s

The fan element is driven by a hydraulic motor powered by hydraulic power from the milling machine and transferred via hydraulic hoses. The motor is attached to the upper wall of the fan cowling. Preferably, the motor is attached to the upper wall of the fan cowling by any conventional releasable means, such as bolting. However, it is also envisaged that the motor may be attached to the

18130229_1 (GHMatters) P115556.AU.1 5/10/21 upper wall of the fan cowling by permanent means, such as riveting or welding. When the motor is attached to the upper wall of the fan cowling, the rotor extends through the second opening and can be secured to the axle of the fan element. Once secured, rotation of the rotor drives rotation of the fan element to produce the differential pressure.

In one exemplary embodiment, the motor may be a Rexroth@ Axial Piston Fixed Motor A2FNM which has the following specifications: Displacement : 10 to 125 cm3 Maximum speed : 2,400 to 8,000 rpm Input flow : 82 to 500 1/min Torque 49 to 597 Nm at a differential pressure of 300 bar Stiffness of drive shaft : 922 to 11,900 Nm/rad Moment of inertia : 0.0004 to 0.0116 kgm 2 2 Maximum angular acceleration : 5,000 to 7,500 rad/s Case volume : 0.17 to 0.80 L Mass (approx.) : 5.4 to 32 kg

It is alternatively envisaged that the motor may be a pneumatic motor, whereby pneumatic power may be transmitted by from the milling machine via fluid conduits, as is otherwise known in the industry.

It is alternatively envisaged that the motor may be an electric motor, whereby electrical power may be transmitted by electrical cables from a source of electric power at the milling machine, e.g. a generator or generator-supplied battery pack.

A louvered vent is fitted to the air outlet 22. The louvered vent comprises a frame with a plurality of

18130229_1 (GHMatters) P115556.AU.1 5/10/21 parallel blades that are pivotably mounted to the frame and are pivotable between: 1) a position in which the air outlet 22 is substantially obstructed to passage of air therethrough; 2) a position in which the air outlet 22 is substantially unobstructed to passage of air therethrough.

By pivoting in this fashion, the louvered vent restricts the amount of air flow through the air outlet 22 into the fan unit 16 but allows, relatively unrestricted, air flow through the air outlet 22 out of the fan unit 16. In other words, the louvered vent acts as a one-way valve for air flow.

Figure 6 shows an exploded view of a housing 12 according to a different embodiment of the invention. As previously discussed, the housing 12 is formed from an assembly comprising an upper box portion 12a and a lower hopper portion 12b.

The upper box portion 12a comprises a series of panel sections, including side wall panels 20, front panels 21a, 21b and rear panel 22 secured in an end-to-end configuration to define an enclosed space. Each panel 20, 21a, 21b, 22 comprises a perimeter flange with holes for receiving fasteners, such as bolts.

The holes in the perimeter flange of the side wall panels 20 have an axis which extend parallel to a plane defined by the side wall panels 20.

The holes in the perimeter flange of the front wall panels 21a, 21b and the rear wall panels 22 have an axis which extend perpendicular to a plane defined by the front wall panels 21a, 21b and the rear wall panel 22.

The rear wall panel 22 also comprises a column of holes in a central region of the rear wall panel 22.

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A pair of 400mm diameter holes 23 extend through the rear wall panel 22 form the suction inlets of the housing 12. Each hole 23 is located either side of the column of holes in the central region of the rear wall panel 22. The difference between the embodiment shown in Figure 6 and the embodiment shown in Figures 1-5 is the positioning of the holes 23 on the rear wall panel 22 as opposed to on each of the side wall panels 20. An advantage to positioning the inlets on the rear wall 22, as opposed to the side walls 20, is that this positioning ensures that the modular dust extraction unit stays within the road width limit of the surface milling machine without having to disconnect hoses from the inlets.

A bracing frame 24 is positioned within the enclosed space and spans between the front wall panels 21a, 21b and the rear wall panel 22. The bracing frame 24 comprises a rectangular perimeter with a diagonal member spanning between opposing corners of the rectangular perimeter. The bracing frame 24 is secured to the adjoining edges of the front wall panel (21a, 21b) flanges and to the centre strip of holes in the rear panel 22.

The hopper portion 12b comprises a perimeter flange 25 with holes for receiving fasteners, such as bolts. The hopper portion 12b is secured to a lower end of the upper box portion 12a by aligning the holes in the flange 25 with corresponding holes along a lower edge of the perimeter flange of each panel 20, 21a, 21b, 22, and inserting fasteners therethrough.

A collar portion 26 is positioned at an upper end of the upper box portion 12a. The collar portion 26 comprises a rectangular perimeter web which defines an enclosed area that corresponds to the internal area of the box portion 12a when viewed in plan. The web is sandwiched between a

18130229_1 (GHMatters) P115556.AU.1 5/10/21 lower flange 27 and an upper flange 28. Each of the lower and upper flanges 27, 28 has holes for receiving fasteners, such as bolts. The web also comprises a plurality of holes along a rear wall of the collar portion 26.

A support frame 30 for supporting the individual air filters is located within the collar portion and mounted to the upper box portion 12a. The support frame 30 comprises a mounting plate having an area corresponding to the internal area of the box portion 12a, when viewed in plan.

The support frame 30 also comprises an upturned lip located along one of the edges of the mounting plate with holes for receiving fasteners. The holes in the upturned lip align with the holes in the flanges of the front wall panel 21a, 21b such that fasteners can be inserted therethrough to secure the support frame 30 to the front wall panel 21a, 21b. The support frame 30 also comprises holes around the perimeter of the mounting plate that align with the holes in the lower flange of the collar portion 26, the side wall panels 20 and the rear wall panel 22 such that fasteners can be inserted therethrough to secure the support frame 30 to the collar portion 26 and the side wall panels 20 and rear wall panel 22.

The support frame 30 also comprises an array of eight holes that extend through the mounting plate and are dimensioned to receive and frictionally retain eight individual air filter bags of a filter unit 18 (as is described below) to the mounting plate. A gasket/seal, such as a silicon O-ring, is positioned around each of the eight holes to provide an air tight seal between the mounting plate and the air filter bags. The mounting plate is suspended, with the air filters attached thereto, in the box portion 12a.

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The housing 12 further comprises a purge system 32. The purge system 32 comprises a manifold with a main line 32a and a plurality of branch lines 32b extending perpendicularly from the main line 32a. Each branch line 32b ends in a nozzle 32c and has a purge valve 32d. By actuating the purge valves 32d, compressed gas (i.e. air) is delivered from an air compressor (not shown) into the housing 12 to clean the air filters of dust particles and other matter. The main line 32a is secured to an external surface of the rear wall panel 22 and the branch lines 32a extend through openings in the collar portion 26 such that the nozzles 32c are positioned above the air filters in use.

In one exemplary embodiment, each purge valve 32d may be a AVS@ DP25 solenoid valve which has the following specifications: Media pressure : 0.5 to 7.5 bar Temperature range : -20 to 800 C Standard voltages : 24VDC, 24, 115, 230V/50-6OHz (±10%) Power consumption : DC-18W, AC-19VA Protection class : IP65 EN60529 with properly mounted connector Connector : PG9 E175301-803 Body : Aluminium Diaphragm : Neoprene, reinforced Pilot group : Stainless steel

A lid 34 is secured to the upper flange on the bracing collar 26 to cover the enclosed space. The lid 34 comprises a central lid panel 34a, and a pair of outer lid panels 34b. The central lid panel 34a is securable to the fan unit 16 and comprises an opening 36 for communicating with the inlet to the fan unit 16 such that air can travel

18130229_1 (GHMatters) P115556.AU.1 5/10/21 from the enclosed space of the housing 12 and into the fan unit 16. The central lid panel 34a comprises a pair of opposing upturned lips which mate with corresponding upturned lips on the outer lid panels 34b when in an assembled configuration. The upturned lips have holes which are alignable and through which fasteners can be inserted to secure the lid panels 34a, 34b together.

As noted, filter unit 18 is located within the housing 12, and in the illustrated embodiment comprises eight individual air filter modules 18a, 18b, 18c, 18d, 18e, 18f, 18g, 18h. Each air filter is an Ultra-Web, Flame Retardant air filter 12.74" OD x 34.00" L (see specifications below). The individual filters 18a-18h are arranged within the box portion 12a of the housing 12. Each air filters 18a-18h is individually removable and replaceable from the support frame described above.

In one embodiment, each of the air filters is a Donaldson@ Ultra-Web filter having the following specifications: Dimensions : 864 x 324 mm 2 Area : 26.8 m Weight : 9.8 kg Material : Ultra-Web, Flame Retardant

The dispensing unit 20 is removably and externally mounted to a bottom portion of the hopper portion 12b. The dispensing unit 20 is in communication with the container unit and comprises a rotary valve that can be actuated for selective removal of precipitated dust particles from the container unit 20 through the lower opening of the hopper portion 12b. The rotary valve is actuated by a motor powered by electrical power from the dust generating machine via electrical cables. Of course, an arrangement may be chosen, although not preferred, that allows manual instead of machine-driven opening / closing of the valve.

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The rotary valve comprises a valve housing with a cylindrical rotating valve element rotatably mounted thereto. The valve housing has an inlet and an outlet positioned at opposite ends of the valve housing. The valve element has longitudinally extending ribs positioned circumferentially around the valve element so as to define a paddle wheel arrangement. As the valve element rotates within the housing, dust particles are scooped from the hopper portion 12b and carried by the ribs from the inlet of the valve housing and out from the outlet of the valve housing. The dust particles are discharged from the outlet of the valve housing in a controlled manner, i.e. proportional to the rotational speed of the valve element. The dust particles exiting the outlet of the valve housing can be collected, for example in a bucket, and disposed of in a conventional manner.

Figures 7 and 8 show a surface milling machine 200 and a modular dust extraction unit 100 according to another embodiment of the present invention. The surface milling machine 200 comprises a milling drum 210 with ground engaging tools for breaking a ground surface into excavated material. The surface milling machine 200 also comprises a material transfer system including a boom with a conveyor 212 for removal of the excavated material away from the ground surface. The modular dust extraction unit 100 is suitable for any surface milling or cold milling machine, including those produced by the following manufacturers: Wirtgen@, CAT@, Bomag@ ... etc. Examples of milling Machine models include Wirtgen@ W210 and W200.

The modular dust extraction unit 100 functions in a similar manner to that of the modular dust extraction unit 10, with the difference: 1) the suction inlets 114a, 114b are located on the rear wall of the upper box portion 112a of the housing 112, as is also shown in the arrangement shown in Figure 6; and

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2) the fan unit 116 is rotated by 90 degrees such that the air outlet 122 is directed towards the rear of the surface milling machine 200.

As previously discussed, the modular dust extraction unit 100 comprises an air purge system comprising an air compressor and manifold. The air purge system delivers compressed air into the filter unit. This enables the air filters to be cleaned of blockages at regular intervals without disassembling the modular dust extraction unit 100. The air purge system can be operated remotely, e.g. from the cabin of the surface milling machine 200.

As shown in Figure 8, the surface milling machine 200 has a duct 214 that extends from a dust collection location at the conveyor 212 to the suction inlet 114a of the modular dust extraction unit 100 to direct a dust particle containing air stream from the conveyor 212 to the suction inlet 114a. The duct 214 is a steel reinforced PVC tube which is mounted at spaced apart locations to an external frame member of the surface milling machine via clamps. At locations intermediate the clamps, the duct 214 is guided/routed by steel cradles which are mounted to the external surface of the surface milling machine.

The Applicant has found that dust creation is high around the conveyor 212. Dust creation is particularly high toward the point 216 on the conveyor where material is discharged, i.e. thrown off, from the conveyor, and a dust collecting hood is installed above such location.

Figures 9A to 9C show a dust collecting hood 215 according to an aspect of the present invention. The dust collecting hood 215 comprises a plate 217 being curved across its width and a spigot 219 projecting from the curved plate 217 at an angle between 20 degrees and 60 degrees relative to the longitudinal extent of the curved

18130229_1 (GHMatters) P115556.AU.1 5/10/21 plate 217. In use, the spigot 219 is inserted into an end of the duct 214. The duct 214 is then secured to the spigot with the use a clamp.

The surface milling machine 200 will also, or alternatively, include a duct that extends from a dust collection location at the milling drum 210 to the suction inlet 114a, 114b of the modular dust extraction unit 100 to direct a dust particle containing air stream from the milling drum 210 to the suction inlet 114a. 114b.

Field tests of the modular dust extraction unit according to the present invention, demonstrate a filtering capacity of 20 kg to 100 kg of dust particles over a 12-hour period. An average of 50 kg of dust particles are collected over a 12-hour period.

As can be appreciated, the present invention provides a flexible, easy to maintain modular dust extraction unit. The modular dust extraction unit can be positioned distal from the dust collection location(s) in an area that is more readily and/or easily accessible for servicing and maintenance. The modular dust extraction unit can be removed and remounted at different locations on the dust generating machine, as and when required. The fan unit and dispensing unit are removably and externally mounted to the modular dust extraction unit's housing and are therefore more accessible for servicing and maintenance. The air filters are individually removable and/or replaceable which reduces servicing cost and downtime. Furthermore, the modular dust extraction unit has a dispensing unit 20 that allows the controlled discharge of dust particles, this allows for ease of emptying the container unit. The fan unit and dispenser unit can be powered by the milling machine, thereby negating any need for a separate source of power which may otherwise lead to a potential point of failure.

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In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

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Claims

1. A modular dust extraction unit, comprising: - a housing configured for permanent or removable mounting to a milling machine; - a suction inlet into the housing connectable via at least one duct to at least one designated dust collection location of the milling machine; - a fan unit arranged for generating negative pressure within the housing to induce a dust particle containing air stream at the designated dust collection location through the suction inlet; - a filter or precipitator unit at or within the housing and in communication with the suction inlet, the filter or precipitator unit configured to remove dust particles from the dust particle containing air stream passing through it; - a container unit at or within the housing and in communication with the filter or precipitator unit to receive dust particles removed by the filter or precipitator unit; - a dispensing unit at the housing in communication with the container unit and arranged for selective removal from the container unit of dust particles accumulated therein; and - a filtered air outlet in communication with the fan unit and filter or precipitator unit and configured to discharge into the surroundings a filtered air stream from which dust particles has been removed.

2. The modular dust extraction unit of claim 1, wherein the fan unit is removably and externally mounted to a top portion of the housing.

3. The modular dust extraction unit of claim 1 or claim 2, wherein the dispensing unit is removably and externally mounted to a bottom portion of the housing.

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4. The modular dust extraction unit of any one of the preceding claims, wherein the filter unit / dust particle precipitation unit is housed within the housing.

5. The modular dust extraction unit of any one of the preceding claims, wherein the container unit is contained within the housing.

6. The modular dust extraction unit of any one of preceding claims, wherein the container unit comprises a hopper having an upper opening and a lower opening.

7. The modular dust extraction unit of claim 6, wherein the dispensing unit controls selective removal of dust particles contained in the container unit through the lower opening.

8. The modular dust extraction unit of any one of the preceding claims, wherein the dispensing unit comprises a valve.

9. The modular dust extraction unit of any one of the preceding claims, wherein the dispensing unit comprises an auger.

10. The modular dust extraction unit of any one of the preceding claims, wherein the dispensing unit comprises a metering wheel.

11. The modular dust extraction unit of any one of the preceding claims, wherein the dispensing unit comprises a rotary valve.

12. The modular dust extraction unit of any one of the preceding claims, wherein the filter unit contains at least four air filters or at least seven air filters.

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13. The modular dust extraction unit of any one of the preceding claims, wherein at least one of the fan unit and dispenser unit are powered via a power source of the milling machine.

14. The modular dust extraction unit of any one of the preceding claims, wherein the filtered air outlet is located on the fan unit.

15. The modular dust extraction unit of any one of the preceding claims, wherein the filtered air outlet comprises a louvered vent.

16. A self-propelled or prime-mover drawn milling machine, comprising: - a ground engaging tool for breaking a ground surface into excavated material; - a material transfer system including a conveyor for removal of the excavated material away from the ground surface towards a conveyor discharge location at the milling machine; - a modular dust extraction unit according to any one of claims 1 to 15 fixedly or removably mounted to a support structure of the milling machine; - at least one dust particle removal duct connected in fluid communication with the suction inlet of the housing unit of the modular dust extraction unit; and - one or more dust extraction hoods mounted on the milling machine in proximity of one or more of the ground engaging tool and at least one selected location along a path of the conveyor, in particular over the conveyor discharge location, the dust extraction hood(s) connected to a respective inlet(s) at the dust particle removal duct such as to provide fluid communication between the suction inlet at the housing unit and the extraction hoods.

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17. A method of reducing air-borne dust particles about and generated during operation of a vehicular or prime mover-drawn milling machine that comprises a ground engaging tool for breaking a ground surface into excavated material, the milling machine having a material transfer system including a conveyor for transporting of the excavated material away from the ground surface towards a conveyor discharge location at the milling machine, including the steps of: - providing a modular dust extraction unit according to any one of claims 1 to 15; - securing the modular dust extraction unit housing to a support structure of the milling machine; - providing at least one dust particle removal duct and connecting same in fluid communication with the suction inlet of the housing unit of the modular dust extraction unit; - locating and mounting respective dust extraction hoods in proximity of one or more of the ground engaging tool and at least one selected location along a path of the conveyor, in particular over the conveyor discharge location; - connecting the dust extraction hoods to one or more inlets at the dust particle removal duct such as to provide fluid communication between the suction inlet at the housing unit and the extraction hoods; and - operating the modular dust extraction unit during the breaking of the ground surface and/or discharging of the excavated material from the conveyor discharge location.

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