SE543878C2 - An arrangement for supplying asphalt and a method of producing an asphalt pavement - Google Patents

Abstract

In a method of and an apparatus for improving the quality of an asphalt pavement, the asphalt is charged in a supply arrangement (2) adapted to be fitted in an inlet space (11) of a road finishing machine (1). The supply arrangement comprises a rotary vessel (3) having a top inlet (30) for receiving the asphalt and a bottom outlet (31) for discharging the asphalt, the bottom outlet (31) being smaller than the top inlet (30); a frame (4) supporting the rotary vessel (3); a bearing arrangement (7) carried by the frame (4) and carrying the vessel (3) rotatably; a motor (6) carried by the frame (4) for enabling rotation of the rotary vessel (3); and a transmission (5) for transmitting a rotation provided by the motor (6) to the rotary vessel (3), and further by providing said rotary vessel (3) with a feeding member (300) comprising at least one pushing member (301) with a feeding surface (301A) attached to the inner surface (304) of the rotary vessel (3).

Description

Upon asphalting of a surface, homogeneousness is important, since it is the worstparts that initiate maintenance measures. ln practice, it is impossible to improve thequality of an asphalt pavement at ambient temperature. Thermographicphotographing reveals segregation problems, which may be caused by the asphaltplant, the transport of the asphalt out on the road, or practical measures inconnection to the change from one lorry batch to the next one.

US 6,122,601 (Swanson et al.) discloses a compacted material densitymeasurement and compaction tracking system, namely a two-component system toobtain uniform density of compacted materials and track the compaction of thematerials. The first component provides an automated, real-time compaction densitymeter and method of use to measure the density of the compacted material. Thesecond component provides a Geographic Information System (GIS) for trackingcompaction of a surface at specific locations. These two components combinedprovide a system to measure the density of the compacted material and record thelocation of each density measurement. The can be utilized for many compactionoperations, such as the roller compaction of concrete, pavement, soil, landfills, andasphalt pavements.

From WO2007106033 there is known a system for preventing separation ofasphalt compositions, comprising separation preventing compartments arranged in asilo, intended for loading of asphalt onto vehicles, separation preventingcompartments intended to be arranged to a deck of a vehicle to be loaded withasphalt, and separation preventing means arranged in a hopper of a paver to be loaded with asphalt from a vehicle. This design is relatively complex and may causejamming problems.

Further, US 2014/0308074 (Rutz et al.) discloses a road finishing machine with athermographic device releasably fixed to a portion of the machine for recording ageoreferenced thermographic data record of at least one region of a pavement layer.The thermographic device includes a housing in which a detection unit for detecting athermographic data record and a further detection unit for detecting a space-relateddata record for the thermographic data record are disposed.

SUMMARY OF THE INVENTION lt is an object according to the invention to provide a method and apparatus that inreliable manner can improve quality of the newly produced asphalt pavement, asdefined in claims 1 and 7.

Thanks to the invention it is achieved a method and apparatus by means of whichit is possible to produce an asphalt pavement that has an improved quality due tosupplying and distributing the asphalt to the paving machine in a state that isconsiderably much more homogenous than prior art methods/apparatuses. Byrotating the rotary vessel including its content of asphalt, the asphalt is made morehomogenous, whereby the sensitivity to formation of tracks in the pavement isreduced and likewise also quality defects caused by the batchwise supply of asphaltto the rotary vessel.

The rotary vessel generally has the shape of a truncated cone convergingdownward and having a substantially vertical symmetry axis, and around which therotary vessel is rotated. Such a shape makes it easy to charge, rotate and empty thevesseL When making an asphalt pavement with conventional technology, the pavementquality on the left-hand side often differs from that on the right-hand side. To at leastreduce this difference, it is preferred to provide a distributing device positioned underthe bottom outlet and adapted to be located above the belt conveyor.

Tests have indicated that an improvement of about 20 % is well within reach bymeans of the invention, which implies enormous savings due to the fact that the lifetime of the pavement will be prolonged proportionally.

Further advantages and preferred embodiments according to the invention will bedescribed in the following detailed description of the invention, which shall not beconstrued to have any limiting effect in relation to the scope of claims. As is evidentfor the skilled person the basic principles according to the invention may be used in avariety of actual method steps.

BRIEF DESCRIPTION OF THE DRAWINGS ln the following, the invention will be described in more detail with reference topreferred embodiments and the appended drawings wherein Fig. 1 is a schematic perspective view of a known pavement machine, i.e. a roadfinishing machine, Fig. 2 shows a schematic perspective view of the pavement machine of Fig. 1arranged in accordance with the invention, including an embodiment of supplyarrangement in accordance with the invention, Fig. 3 shows a schematic perspective view of an embodiment of the supplyarrangement in accordance with the invention, seen from behind, Fig. 4 shows a schematic perspective view of an embodiment of the supplyarrangement in accordance with the invention, seen from the front, Fig. 5 shows a schematic view from above of a preferred embodiment of thesupply arrangement in accordance with the invention, Fig. 6 shows a partial vertical cross-sectional view along Vl-Vl in Fig 5, of thepreferred embodiment, Fig. 7 shows a plan view of a distributing device that may be used together withwith the invention, and, Fig. 8 shows a vertical cross-sectional view through the distributing device of Fig.

MODE(S) FOR CARRYING OUT THE INVENTION ln Fig. 1 there is shown a road finishing machine 1, preferably provided with asensor 10 for scanning the temperature of an asphalt pavement P directly after layingof the asphalt pavement. The sensor 10 preferably is in form of line scanner thatmeasures the IR radiation. ln the preferred embodiment, the line scanner 1 is connected to a quality measurement system as disclosed in WO2016198333, whichis herewith introduced by way of reference.

Further the pavement machine has an in|et space 11 for supply of asphalt, e.g.from a truck (not shown). ln the bottom of the in|et space 11 there is a belt conveyor12 (e.g. belt conveyor or screw conveyor), or two parallel conveyors 12 that feed theasphalt to the screed 13 of the pavement machine, whereby asphalt is distributed toform a pavement P. The screed 13 distributes the asphalt widthwise and levels andshapes it, and it usually includes |eve|ing arms, moldboard, end plates, burners,vibrators, and slope sensors and controls. ln Fig. 2, there is shown a pavement machine 1 of Fig. 1 provided with a supplyarrangement 2 in accordance with the invention. Accordingly, the supplyarrangement 2 is intended to be used in connection with already existing pavementmachines 1 but may of course also be used in connection with new kind of pavementmachines. As is evident from the following the supply arrangement 2 preferably isarranged with devices (see items 30, 45, 46) that will facilitate shifting of the supplyarrangement 2 from one place to another, e.g. different pavement machines 1.

The supply arrangement 2 comprises a conical rotary vessel 3, a frame 4,rotatably supporting the rotary vessel 3, and as shown in Figs. 3 and 4, a bearingarrangement 7, a transmission 5, and a motor 6 for enabling rotation of the rotaryvessel 3. Below the rotary vessel 3 there may be a distributing device 9, shown inFigs. 7 and 8, for optimizing the distribution of asphalt supplied by the feedingarrangement/conveyor 12.

As shown in Figs. 3, 4 and 5 the rotary vessel 3 generally has the form of atruncated cone that has a substantially vertical rotation axis C and a larger opening atthe top forming an in|et 30 and a smaller opening 31 at the bottom forming an outlet.Preferably the inner side of the vessel 3 has a surface 304 provided with some kindof irregularities 32, providing a kind of engagement to the asphalt within the vessel 3to safe guard that the asphalt follows the rotation of the vessel 3, to improve a mixingeffect. ln the preferred embodiment, these irregularities 32 may for instance beformed by folding a plurality of valleys along vertical planes or by welding flat sub-plate members 33 to form corresponding valleys. ln this manner, there is formed akind of valleys 32 between plate members assisting in providing a kind of engagement to asphalt within the vessel 3. lt is evident for the skilled person thatmany different kind of engagement members 32 may be used, as will be presentedmore in detail in relation to Fig 5. below. ln a preferred embodiment as indicated in Fig 3 and shown in Figs. 5 and 6, thevessel 3 is arranged with a feeding member 300 attached adjacent the outlet 31 ofthe vessel, to safe guard that the material also in connection with low fill levels in thevessel 3 will rotate together with the rotation of the vessel 3. The feeding member300 preferably comprises at least one pushing member 301 that provides a feedingsurfaces 301A, that will push on the material to follow the rotation of the vessel 3 andthereby assist in providing the desired rotation of the material. More preferred there isarranged at least two pushing members 301, by means of at least one plateextending along a chorda of the vessel 3.

As shown in Fig. 5 in one embodiment there is provided four pushing members301 providing four feeding surfaces 301A, by arranging four plates 306, 307, 308,309, joined at the center C to form a cross member, i.e. having two perpendicularparts extending along the diameter chorda of the vessel 3. Each plate 306, 307, 308,309 is at its outer end attached to the inner peripheral surface 304 of the vessel 3.Accordingly, such a feeding member 300 will provide four feeding surfaces 301A thatwill push on the material to follow the rotation of the vessel 3 and thereby assist inproviding the desired rotation of the material. ln an alternate embodiment the platesof the feeding member 300 may be shorter and have their inner ends attached to anannulus (not shown) or merely comprise one plate along a chosen chorda orcomprise two or more plates arranged along shorter chordas than the diameter.

As shown in Fig. 3 a plate used for this purpose should present a certain height Yto provide a sufficient feeding surface 301A. ln a preferred embodiment the height isin the range of 50-300 mm, more preferred 100-200 mm. Further the lower edge of aplate should preferably be arranged at a distance above the edge of the outlet 31,e.g. in the range of 50-200 mm, which may provide further assistance inhomogenization of the asphalt, i.a. by arranging for randomly distributing asphaltsupplied from different batches and/or layers in a batch.

As shown in Figs. 2-4 the upper outer side of the vessel 3 may be arranged withskirt 34 that is rigidly attached to the frame 4 and that may provide protection andinsulation. ln many applications, as shown in Fig 6, it may be preferred to not use askirt 34.

The transmission 5 includes an annu|ar gear 50 that is rigidly connected to therotary vessel 3 and in meshing engagement with a drive gear 51 driven by the motor6.

The frame 4 may preferably include three connected base beams, i.e. two parallelside beams 40 and one transversal beam 41 at the front. Extending upwardly from the base beams 40, 41 there are a plurality of support beams 43, supporting a fixed part 73 of a bearing and also a support platform 44 for the motor 6 and drive gear 51.

A forvvardly extending frame part 47 carries lifting eyelets 45 or similar devices (alsopreferably provided at the top of the rotary vessel 3), a load exchanging member 46and wall members 49A, 49B. Preferably the side beams 40 are length adjustable byarranging telescopically adjustable beam members 48, which may be adjusted toextend the length of the sides. ln Fig. 6 there is a detailed view of the rotary part of the transmission 5 and thebearing 7. As shown, the annu|ar gear 50 has an inner side 70 that forms the rotarysurface of the bearing 7, in radial sliding (lubricated) contact with the outer surface ofa fixed bearing ring 71. Balls 72 may be used to take the axial load. The drive gear51 interacts with the outwardly protruding teeth 52 of the annu|ar gear 50. Theannu|ar gear 50 is fixed to a transmission ring welded onto the outer side of therotary vessel 3. The fixed bearing ring 71 is fixed to bearing part 73, which in turn isfixed to the support beams 43.

Further, Fig 5 shows that a plurality of feeding ribs 303 may be attached to theinner surface 304 of the vessel 3, which extend along vertical planes from a positionadjacent the outlet to a position above half the height of the vessel 3.

At the bottom of the vessel, and in close proximity to the outlet 31, there isprovided a distributing device 9. As indicated in Figs. 7 and 8, the distributing device9 is intended to be positioned between the outlet 31 and the conveyor 12 of the paving machine 1, i.e. between the side beams 41.

The distributing device 9 has a width W that substantially corresponds to thediameter D of the outlet 31 of the vessel 3. The length thereof is adapted to be agood fit within the paving machine 1. The distributing device 9 has two parallel outerframe members 90, 91 extending Iongitudinally in relation to the paving machine 1,i.e. the feed direction of the conveyor 12. A plurality of dividing members 93 arearranged transverseiy from one side to the other within the distributing device 9, i.e.from one longitudinal frame member 90 to the other 91. Each dividing member 93A-93E has a different height h. At a most upstream position (with reference to the feeddirection of the conveyor 12) there is a first dividing member 93A having the largestheight, h1. ln parallel therewith there are positioned a plurality of further such dividingwalls 93B-93E, wherein each dividing wall in the direction towards the discharge endof the conveyor the height h decreases for each dividing wall. ln the shown example,there are positioned five such dividing walls 93A-93E, wherein each of said dividingwalls is positioned such that it crosses at least a subsection of the circle defined bythe outlet 31 from the vessel 3. Accordingiy, the total distance between the fivedividing walls in the longitudinal direction is substantially the same as or less than thediameter D of the outlet 31. Further, as is shown there is a substantially proportionaldecrease of the height h in the direction of feeding, such that the first dividing wall93A has a heighth1 that is 5 times the height h5 of the final dividing wall 93E. Theheight h1 of the first dividing wall 93A will be smaller than height H of the framemembers 90, 91, such that there is created a gap g between the lower end thereofand the conveyor 12, which gap will get larger and larger in the feeding direction.

Furthermore, at the far end, downstream, of the distributing device 9 there isarranged a rearrangement device 95. The rearrangement device 95 has a concavesurface 95A directed “obliquely” against the flow of asphalt that is supplied by meansof the conveyor 12, forming a kind of roof that is higher at the center than near thesides, so that the asphalt layer on leaving the distributing device 9 is cambered. Therearrangement device 95 will create a form of the bed of asphalt leaving it, such thatit minimizes, preferably eliminates, slipping of parts of the bed of asphalt, e.g. bycreating sides that do not slope more than 45°. Further the rearrangement device 95 will create a counter pressure that is also beneficial.

The function of the invention is as follows. The supply arrangement 2 is fitted intoa paving machine 1, preferably by Iifting it into the supply space 11 by use of theIifting eyelets 45. The distributing device 9 may be positioned on top of the conveyormember/s 12 of the paving machine 1 before or aftenNard. ln any case the rotaryvessel 3 and its frame 4 are positioned on top of the distributing device 9 to bepositioned as indicated in Fig. 6. ln operation, asphalt will be supplied into the rotary vessel 3 from above, e.g. bymeans of an intermediate feeder that is supplied from a truck tipping asphalt from itsflatbed (not shown), i.e. in a conventional manner for supplying asphalt to the pavingmachine 1. Thanks to the rotation of the rotary vessel 3, the asphalt supplied will bethoroughly intermixed, whereby temperature differences that have appeared due tothe transport and/or storage will be leveled-out. ln a preferred manner then asphalt issupplied off-centered to the rotary vessel 3, i.e. onto the inner surface 304 of therotary vessel, in order to possibly further improve intermixing of the asphalt in therotary vessel. The conveyor 12 of the paving machine 1 continuously moves duringoperation and accordingly will bring along the asphalt A that is supplied on to it viathe outlet 31 of the rotary vessel 3.

The distributing device 9 may provide for a further leveling out of the asphaltmixture by means of the dividing walls 93. A first volume A1 will be supplied near thebottom of the distributing device 9 in connection with a first dividing wall 93A adjacentthe upstream end of the conveyor 12. Thereafter, a second volume A2 will be added(on top of the first volume A1) that is supplied down between the first dividing wall93A and the second dividing wall 93B, etc., and moved by the conveyor 12 towardsthe outlet end 94 of the distributing device 9. At the outlet end 94 of the distributingdevice 9, a final rearrangement device 95 is provided, the rearrangement device 95will create a form of the bed of asphalt leaving it, such that it minimizes, preferablyeliminates, slipping of parts of the bed of asphalt, e.g. by creating sides that do notslope more than 45°. Further the rearrangement device 95 will create a counterpressure that is also beneficial. Thanks to the invention very much more evenlydistributed asphalt will be supplied to the paving machine 1, which will improve thequality of the asphalt.

Tests have indicated that an improvement of about 20 % is well within reach bymeans of the invention, which implies enormous savings, due to the fact that the lifetime of the pavement will be prolonged proportionally.

The invention is not limited to what is defined above but may be varied within thescope of the claims. For instance, it is evident that a pavement machine 1 withoutsensor 10 and without a distributing device 9 may be used to achieve the basicadvantages of the invention. Moreover, the ski||ed person realizes that in someapplications in may be sufficient to use merely one dividing member 93 arrangedtransversely from one side to the other within the distributing device 9, and in otherstwo or three or perhaps more than five. Further it is to be understood that therearrangement device 95 may be positioned adjacent the outlet end 94 or anywherebetween the outlet end 94 and the position for the outlet. Moreover, it is evident thatmany of the expression used are in no way limiting, e.g. that the relationship value may take other formats than the one exemplified above.

Claims (13)

1. A method of producing an asphalt pavement, wherein asphalt is fed to a roadfinishing machine (1) having an inlet space (11), a screed (13), and a conveyor(12) forming a bottom of the inlet space (11) and conveying the asphalt to thescreed (13) for |eve|ing the layer of asphalt and partially compacting it to adesired shape, said method comprising: a) providing a supply arrangement (2) for supplying asphalt to the conveyor(12), said supply arrangement (2) being adapted to be fitted in the inletspace (11) and including: - a rotary vessel (3) having a top inlet (30) for receiving the asphalt and abottom outlet (31 ) for discharging the asphalt, the bottom outlet (31)being smaller than the top inlet (30), wherein the rotary vessel (3)generally has the shape of a truncated cone converging downward_andhaving a substantially vertical symmetry axis (C), and the rotary vessel(3) is rotated around the symmetry axis (C); b) positioning the supply arrangement (2) in the inlet space (11); c) charging asphalt in the rotary vessel (3), d) rotating the rotary vessel (3) to homogenize the asphalt as to particle sizeand temperature; and e) continuously letting asphalt flow from the bottom outlet (31) of the rotaryvessel (3) down onto the conveyor (12),characterized by,providing a frame (4) supporting the rotary vessel (3);- a bearing arrangement (7) carried by the frame (4) and carrying thevessel (3) rotatably;- a motor (6) carried by the frame (4) for enabling rotation of the rotaryvessel (3); and- a transmission (5) for transmitting a rotation provided by the motor (6) to the rotary vessel (3), andfurther by providing said rotary vessel (3) with a feeding member (300) comprising at least one pushing member (301) attached to the inner surface 11 (304) of the rotary vessel (3) and rotating said rotary vessel (3) to therebycause a feeding surface (301A) of said pushing member (301) to pushasphalt in the direction of rotation of the rotary vessel (3). A method as claimed in claim 1, and wherein the lower edge of said pushingmember (301) is arranged at a distance above the edge of said outlet (31 ). A method as claimed in claim 2, further comprising improving thehomogenization by providing irregularities (32) on said inner surface (304) ofthe rotary vessel (3), wherein preferably the irregularities (32) are in the form ofvaHeys. A method as claimed in any one of c|aims 1-3, further by providing said feedingmember (300) with a p|ura|ity of pushing members (301) attached to the innersurface (304) of the rotary vessel (3). A method as claimed in claim 1, further positioning a distributing device (9)under the bottom outlet (31) and above the conveyor (12), comprising twoparallel outer frame members (90, 91) extending in the feed direction of theconveyor (12); and at least one dividing member (93) extending transverselyfrom one outer frame member (90) to the other (91 ), the dividing member (93)being adapted to be spaced from the conveyor (12) by a gap (g), and by: - dividing the flow of asphalt from the bottom outlet (31) into a p|ura|ity oflayers by making the asphalt pass through passages on each side of the atleast one dividing member (93) to the conveyor (12); and - feeding the p|ura|ity of homogenized asphalt layers on top of one another bythe conveyor (12). A method as claimed in claim 1, wherein the distributing device (9) comprises: - a p|ura|ity of, parallel dividing member/s (93) extending transversely fromone outer frame member (90) to the other (91), the dividing members (93)being adapted to be spaced from the conveyor (12) by gaps (g) of differentsize, wherein the size of the gaps (g) increasing in the feed direction of theconveyor (12). 10. 12 - dividing the flow of asphalt from the bottom outlet (31) into a plurality oflayers by making the asphalt pass through passages on each side of thedividing members (93) to the conveyor (12). A supply arrangement for supplying asphalt pavement, said supply arrangement adapted to be included in an arrangement for supplying asphalt to a road finishing machine (1), said road finishing machine (1) having an inlet space (11), a screed (13), and a conveyor (12) forming a bottom of the inlet space (11) and conveying the asphalt to the screed (13), said supply arrangement being adapted to be fitted in the inlet space (11) and comprising: - a rotary vessel (3) having a top inlet (30) for receiving the asphalt and a bottom outlet (31) for discharging the asphalt, the bottom outlet (31) being smaller than the top inlet (30), wherein the rotary vessel (3) generally has the shape of a truncated cone converging downward and having a substantially vertical rotation axis (C), characterized by, - a frame (4) supporting the rotary vessel (3); - a bearing arrangement (7) carried by the frame (4) and carrying the vessel(3) rotatably; - a motor (6) carried by the frame (4) for enabling rotation of the rotary vessel(3); and - a transmission (5) for transmitting a rotation provided by the motor (6) to therotary vessel (3), and further wherein said rotary vessel (3) is arranged witha feeding member (300) comprising at least one pushing member (301)witha feeding surface (301A) attached to the inner surface (304) of the rotaryvessel (3) A supply arrangement as claimed in claim 7, wherein the lower edge of saidpushing member (301) is arranged at a distance above the edge of said outlet(31 ). A supply arrangement as claimed in claim 7 or 8, wherein said feeding member(300) comprises a plurality of pushing members (301) attached to the innersurface (304) of the rotary vessel (3). A supply arrangement as claimed in any of claims 7 - 9, wherein the innersurface (304) of the rotary vessel (3) is arranged with irregularities (32). 11. 1

2. 1

3. 13 A supply arrangement as c|aimed in claim 10, wherein said irregularities (32)are formed by valleys between sub-plate members (33) that constitute the wallwith said inner surface (304). A supply arrangement as c|aimed in claim 10 or 11, wherein said irregularities(32) include engagement members (303) that protrude from said inner surface(304), preferably in the form of Iongish ribs that extend substantially in a verticalplane. A supply arrangement as c|aimed in any one of c|aims 10-12, furthercomprising a distributing device (9) located under the bottom outlet (31) of therotary vessel (3) comprising two parallel outer frame members (90, 91); and, atleast one dividing member (93) extending transversely from one outer framemember (90) to the other (91), the at least one dividing member (93) beingspaced from the conveyor (12) to form a gap (g) between it and the conveyor(12).