Dust retention system

A dust retention system for locating above a product vessel includes a support member mounted above the product vessel, a door including an engaging portion detachably connected to the support member and an adjustment device for adjusting the angle of the door with respect to the support member. The door includes a striking portion adjacent the engaging portion with at least a section of the striking portion being constructed of a resiliently flexible material. Product falling onto the striking portion causes the resiliently flexible material of the striking portion to be deflected by the weight of the product, thereby forcing the door from a closed position, where dust is prohibited from escaping the product vessel, into an open position where the product passes across the door into the product vessel. Thereafter the door, without the weight of said product, returning to the closed position under a bias force exerted by said resiliently flexible material.

FIELD OF THE INVENTION
 The present invention relates generally to a door for installation in a
 dust retention system designed to be located above a product vessel.
 BACKGROUND OF THE INVENTION
 When dumping grain from a road train into a hopper a significant amount of
 dust is thrown up from the hopper the dust can "envelope" the road train
 and linger for some time. Mechanical dust retention systems have been
 designed to contain dust within the hopper so as to overcome or at least
 reduce this problem. A known dust retention system consists of a series of
 pressed steel doors hinged to a longitudinal beam which forms part of a
 grated floor structure through which the road train dumps the grain. Each
 of the steel doors is hinged at several points with a torsion spring
 acting on the door so as to urge it closed in an upward direction.
 Although the known dust retention system is relatively inexpensive to
 manufacture it suffers from at least the following drawbacks:
 i) the hinged doors rely on moving parts for operation which require
 frequent maintenance or replacement;
 ii) the hinged doors are, with the sound of grain impacting on the solid
 steel surface, relatively noisy;
 iii) the doors are difficult to install demanding a relatively large amount
 of downtime;
 iv) the doors are subject to corrosion thereby requiring cleaning and
 frequent maintenance; and,
 v) the rate of flow of particulate material is unacceptably restricted.
 Also, it is known to have flexible doors which flex under the weight of
 particulate material being dumped onto the flexible doors. It is difficult
 to correctly position the flexible doors for use at a desired angle to the
 floor structure. In addition the flexible doors often need adjustment or
 maintenance. There is therefore a need for a means of adjusting the
 flexible doors that also accommodates maintenance of the dust retention
 system.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a dust retention system
 which provides for easy adjustment of a door in the dust retention system.
 According to the present invention there is provided a dust retention
 system for location above a product vessel, said system comprising:
 a support member adapted to be mounted above the product vessel; and,
 a door including an engaging portion detachably mounted on the support
 member and retained in place by an adjustment means for adjusting the door
 to a desired angle with respect to the support member, the door also
 including a striking portion adjacent the engaging portion with at least a
 section of the striking portion being constructed of a resiliently
 flexible material;
 whereby, in use, product falling onto the striking portion causes the
 resiliently flexible material of the striking portion to be deflected by
 the weight of said product thereby forcing the door from a closed
 position, where dust is inhibited from escaping the product vessel, into
 an open position where the product passes across the door and into the
 product vessel, and thereafter the door, without the weight of said
 product, returning to the closed position under a bias force exerted by
 said resiliently flexible material. Preferably, the door is detachably
 mounted substantially above the support member.
 Preferably, the adjustment means includes a retainer for retaining the door
 on the support member and for retaining the door at said desired angle to
 the support member. Preferably the retainer cooperates with the support
 member to apply oppositely directed forces on the door in order to
 maintain the door at said desired angle.
 Typically, the retainer applies a downward force to the door and the
 support member applies an upward force to the door, wherein the upward
 force is applied to a point of the engaging portion closer to the striking
 portion, than a point of the engaging portion where the downward force is
 applied. The support member acts as a fulcrum balancing the weight of the
 striking portion against the downward force applied by the retainer.
 Typically, the retainer is an elongate member, having a V-shaped cross
 section.
 Preferably, the adjustment means further includes one or more adjustable
 fasteners that fasten the retainer and the engaging portion to the support
 member. Typically, each fastener is a bolt secured with a nut.
 Preferably, the support member includes a flange for the engaging portion
 of the door to sit on, wherein the flange applies an upward force to the
 door, More preferably, the downward force is applied to the door by the
 tip of the V-shaped member.
 Typically, the door is generally oblong shaped with the engaging portion
 formed along a longitudinal edge thereof. More typically, two doors are
 formed integrally with one another to form a double door member, wherein
 the two doors are joined along a longitudinal edge.
 Preferably, the flange on the support member is one of a pair of opposed
 flanges, each one acting as the flange for each door of the double door
 member.
 Preferably, each adjustable fastener extends from the support member
 upwardly through a hole in the engaging portion of the doors of the double
 door member and through a hole in the retainer to sandwich the engaging
 portion between the retainer and the support member.
 Preferably, the engaging and striking portions of the door are formed
 integral with each other. More preferably, the striking portion is
 constructed entirely from the resiliently flexible material.
 Typically, the resiliently flexible material is a metallic material. More
 typically, said material is stainless steel spring sheeting. In one
 embodiment the stainless steel spring sheeting is Grade 304.
 Typically, the striking portion of the door is constructed of a sheet
 material of substantially constant thickness. In one embodiment, the sheet
 material is less than approximately 1 mm in thickness.
 Typically, the support member is a rail. More typically, the rail includes
 a longitudinal groove designed to releasably engage the fastener of the
 adjustment means so as to detachably connect the doors and adjustment
 means to the rail. Preferably, the groove includes a keyway formed
 continuous with the longitudinal groove and has a shape that is
 complementary to a head of the fastener. Preferably, the longitudinal
 groove is positioned between the two opposed flanges.
 Preferably, each of the doors of the double door member extend from the
 support member at an angle of between approximately 20.degree. to
 40.degree. relative to a horizontal plane. Advantageously, this allows for
 a relatively free flow of the product under the influence of gravity
 across the doors and into the product vessel. Preferably, the angle of the
 V-shaped member is less than an angle between the doors of the double door
 member.
 Typically, opposing ends of the support member are configured to detachably
 mount to opposing beams disposed above the product vessel. More typically,
 opposing ends of the support member each include a recess shaped to
 removably locate each end of the support member upon a corresponding lug
 of each of the opposing beams.
 Typically, the support member and the doors of the double door member form
 a double door row that is one of a series of form a double door row that
 detachably mounted between and disposed transverse to a pair of opposing
 beams so that a space defined between said opposing beams is substantially
 sealed to inhibit the escape of dust from the product vessel. More
 typically, the series of double door rows are arranged so that with said
 doors in a closed position, a relatively small gap exists between the
 opposite edges of the doors facing each other. The relatively small gap
 allows any product resting on the door adjacent said opposite edge to fall
 into the product vessel so as to avoid contamination of product in said
 vessel.
 Typically, the product vessel is a hopper or a silo. In one example, the
 product is grain where dust problems are particularly prevalent when
 loading a hopper or silo. Alternatively, the product is sugar, coal,
 sands, woodchips, or practically any other product where dust control
 during loading/unloading is beneficial.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
 As shown in FIG. 1, there is a dust retention system shown generally as 10
 comprising a series of support members or rails 12 and doors 14. Although
 not illustrated in FIG. 1, the doors 14 are each generally oblong-shaped.
 A pair of doors 14 are arranged to integrally form an inverted V-shaped
 double door.
 The rails 12 are mounted between longitudinal I-section beams 16 of a
 grated floor structure 18. A series of transverse grating bars 20 are
 welded across an upper surface of the longitudinal I-section beams 16. The
 grated floor structure 18 is designed so that a road train or the like
 (not shown) can drive over the transverse bars 20 and dump its load which
 may include grain, sugar, coal, sands, wood chips or any other product.
 The product passes through the grated floor structure 18 into one or more
 product vessels or hoppers (not shown) located beneath the floor structure
 18.
 In this embodiment, a series of two support pins 22 are welded to opposing
 faces of the I-section beams 16 so that each of the rails 12 can removably
 mount between the longitudinal beams 16.
 As depicted in FIG. 2, each of the rails 12 has a recess 24 formed in a
 bottom portion thereof. The recess 24 is substantially rectangular in
 cross-section in a shape complementary to each pair of the pins 22,
 whereby each of the rails 12 can located upon the pins 22. The rail 12
 also includes a longitudinal groove 26 formed on an upper surface of the
 rail 12. The longitudinal groove 26 is disposed between a pair of opposed
 flanges 38 which extend outwardly from the centre of the rail 12 so as to
 together define a substantially horizontal plane.
 The rails 12 of this embodiment are constructed of an extrudable aluminium
 alloy material. However, it will be appreciated that other materials such
 as a plastics material of suitable strength may be used.
 As shown in greater detail in FIG. 2, the angle of each door 14 in relation
 to the rail 12 is adjustable by means of a retainer 42 in the form of a
 V-shaped member positioned in an invented manner on the pair of doors 14.
 A fastener in the form of a bolt 40 and a nut 48 sandwiches the doors
 between the V-shaped member 42 and the rail 12. Extreme ends (or tips) 52
 of the V-shaped member exert a downward force on the doors 14, while the
 ends of flanges 38 exert an upward force on the doors 14. The ends of the
 flanges are wider apart from one another than the ends 52. The combination
 of upward and downward forces acts to hold the door 14 at a desired angle
 relative to the rail 12. More specifically, the upward force of the end of
 the flange is caused by it acting as a fulcrum. It balances a downward
 force applied by the weight of a striking portion 32 of door 14 against
 the downward force applied by the tip 52 of the V-shaped member.
 As depicted in FIG. 1, each of the doors 14 includes an engaging portion 30
 formed continuously with a striking portion 32 (encircled in broken
 lines). The engaging portions 30 of the double door are configured to
 detachably connect to one of the rails 12 via one or more fasteners 40
 which pass through a respective hole in the join between each door 14 of
 the double door. The retainer 42 then sits on the engaging portions 30 of
 the doors.
 The striking portion 32, as the terminology suggests, is designed to be
 "struck" by any product falling through the grated floor structure 18 into
 a hopper located thereunder.
 The striking portion 32 of each door 14 is constructed of a sheet material
 of substantially constant thickness. Although not illustrated, an opposite
 longitudinal edge of the door 14 may be beaded. Particularly when the
 doors 14 are extruded from a plastics material, the beaded edge forms a
 relatively straight and stiff edge.
 Each door 14 is constructed of a resiliently flexible material such as a
 metallic or alternatively a plastics material. In one embodiment, the
 doors 14 are constructed of Grade 304 stainless steel spring sheeting
 having a thickness of approximately 0.6 mm.
 The longitudinal groove 26 in the rail 12 includes a key-way 46 formed
 continuously along the length of the longitudinal groove 26 and of a
 complementary shape to a head 44 of the bolt 40.
 The rail 12 includes a hole 50 extending through bottom portion of the rail
 12 and the recess 24 so that a clip may be inserted into the hole 50 so as
 to secure the rail 12 to one of the pins 22.
 In order to facilitate a further understanding of the present invention
 operation of the dust retention system described above will now be
 explained.
 To assemble the dust retention system 10, bolts 40 are slid into the
 longitudinal groove 26, SO that the head of the bolt 44 is within the
 keyed recess 46, as seen in FIG. 3. The bolts 40 are spaced apart at a
 distance so as to align with holes in the double doors. The rails 12 are
 positioned on the pairs of pins 22 so that the recess 24 sits on opposed
 pairs of pins 22 within the grated floor structure 18 as seen in FIG. 4. A
 clip is inserted into the hole 50 to secure the rails in position.
 The double door members are placed on top of the rails 12 so that the bolts
 40 extend upwardly from the rails 12 passes through the corresponding
 holes in the double doors. The V-shaped member 42 is positioned on top of
 the double doors in an inverted manner so that the upwardly projecting
 bolt 40 passes through corresponding holes in the V-shaped member. The
 tips of the V rest on the doors 14.
 The nuts 48 are secured to each corresponding bolt 40 and then tightened so
 as to move the position of the tips 52 of the V-shaped member closer to
 the rail 12 thereby sandwiching the engaging portion thus altering the
 angle of the doors 14 in relation to the rail 12. This will flatten the
 doors or reduce their angle to the horizontal and decrease the angle to
 each other. Equally, the bolts may be loosened to decrease the sandwiching
 force applied and increasing the distance of the tips 52 from the rail 12,
 which will cause them to droop or increase the angle of the doors 14 to
 the horizontal and decrease the angle to each other.
 The pairs of pins 22 are spaced so that with the doors 14 in a closed
 position there is a slight gap 36 between opposing beaded edges of the
 doors 14. The gap 36 allows excess product retained on the door 14 to pass
 therethrough. This ensures that when a different product is dumped through
 the grated floor structure 18 the product within the hopper is not
 contaminated.
 FIG. 1 illustrates an opposing pair of doors 14 in both the closed position
 and an open position (on a left and right hand side of FIG. 1,
 respectively). Product being dumped through the floor structure 18 falls
 onto the striking portion 32 of the doors 14 forcing said doors 14 from
 the closed position into the opened position. In the closed position dust
 is inhibited from escaping the hopper located beneath the floor structure
 18. In the opened position the resiliently flexible doors 14 are deflected
 by the weight of the product so that the product passes across the doors
 14 and into the product hopper. Once the weight of product comes off the
 doors 14 they return to the closed position under a bias force exerted by
 the resiliently flexible material from which the doors 14 are constructed.
 Thus, the doors 14 automatically open upon dumping of a product and close
 once dumping of the product has stopped.
 Now that a possible embodiment of the present invention has been described
 in some detail it will be apparent to those skilled in the art that the
 dust retention system has at least the following advantages over the
 admitted prior art:
 (i) due to the system including resiliently flexible doors there are no
 moving parts and thus little maintenance is required;
 (ii) the system, being modular in construction, can be repaired/maintained
 with relatively quick door and/or rail replacement;
 (iii) the system is relatively quiet when in operation, the only noise
 resulting from product brushing over the rails and doors;
 (iv) the system is relatively effective in preventing the egress of dust
 wherein the doors automatically return to a closed position relatively
 quickly once the dumping of product stops;
 (v) the doors and/or rails are suited to non-corrosive materials thereby
 requiring minimum maintenance;
 (vi) the angle of the doors in relation to the rails is adjustable; and,
 (vii) the flow of particulate material is not significantly impeded by the
 doors and supporting rails, in fact the restriction is less than 15%,
 compared to a restriction rate of about 60% of the device of EP 0,015,651.
 Those skilled in the art will appreciate that the invention described
 herein is susceptible to variations and modifications other than those
 specifically described. For example, the door may be connected to the
 supporting member by bolting or fixing in another manner. Further, the
 door may not be constructed entirely from the resiliently flexible
 material but rather include a web of said material that allows the door to
 resiliently deflect about the support member. The adjusting means may be
 of a different configuration such that the protrusions of the rail sit on
 top of the doors and an adjustable support member extends outwardly from
 the rail and supports the doors.
 All such variations and modifications are to be considered within the scope
 of the present invention, the nature of which is to be determined from the
 foregoing description and the appended claims.