SUPPLYING ASPHALT PAVEMENT

FIELD OF INVENTION

The present invention relates to an apparatus and a method of improving the quality of an asphalt pavement.

In the present context, the term "asphalt" is intended to mean a mixture consisting of mineral aggregate bound together with asphalt (bitumen). BACKGROUND OF THE INVENTION

Upon asphalting of a surface, homogeneousness is important, since it is the worst parts that initiate maintenance measures. In practice, it is impossible to improve the quality of an asphalt pavement at ambient temperature.

Thermographic photographing reveals segregation problems, which may be caused by the asphalt plant, the transport of the asphalt out on the road, or practical measures in connection to the change from one lorry batch to the next one.

US 6,122,601 (Swanson et al.) discloses a compacted material density measurement and compaction tracking system, namely a two-component system to obtain uniform density of compacted materials and track the compaction of the materials. The first component provides an automated, real-time compaction density meter and method of use to measure the density of the compacted material. The second component provides a Geographic Information System (GIS) for tracking compaction of a surface at specific locations. These two components combined provide a system to measure the density of the compacted material and record the location of each density measurement. The can be utilized for many compaction operations, such as the roller compaction of concrete, pavement, soil, landfills, and asphalt pavements.

From W02007106033 there is known a system for preventing separation of asphalt compositions, comprising separation preventing compartments arranged in a silo, intended for loading of asphalt onto vehicles, separation preventing compartments intended to be arranged to a deck of a vehicle to be loaded with asphalt, 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 cause jamming problems.

Further, US 2014/0308074 (Rutz et al.) discloses a road finishing machine with a thermographic device releasably fixed to a portion of the machine for recording a georeferenced 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 a thermographic data record and a further detection unit for detecting a space-related data record for the thermographic data record are disposed.

SUMMARY OF THE INVENTION

It is an object according to the invention to provide a method and apparatus that in reliable manner can improve quality of the newly produced asphalt pavement, as defined in claims 1 and 7.

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

Suitably, the rotary vessel generally has the shape of a truncated cone converging downward and having a substantially vertical symmetry axis, and the rotary vessel is rotated around the symmetry axis. Such a shape makes it easy to charge, rotate and empty the vessel.

When making an asphalt pavement with conventional technology, the pavement quality on the left-hand side often differs from that on the right-hand side. To at least reduce this difference, it is preferred to provide a distributing device positioned under the bottom outlet and adapted to be located above the belt conveyor. Tests have indicated that an improvement of about 20 % is well within reach by means of the invention, which implies enormous savings due to the fact that the life time of the pavement will be prolonged proportionally.

Further advantages and preferred embodiments according to the invention will be described in the following detailed description of the invention, which shall not be construed to have any limiting effect in relation to the scope of claims. As is evident for the skilled person the basic principles according to the invention may be used in a variety of actual method steps. BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail with reference to preferred embodiments and the appended drawings wherein

Fig. 1 is a schematic perspective view of a known pavement machine, i.e. a road finishing machine,

Fig. 2 shows a schematic perspective view of the pavement machine of Fig. 1 arranged in accordance with the invention, including an embodiment of supply arrangement in accordance with the invention,

Fig. 3 shows a schematic perspective view of an embodiment of the supply arrangement in accordance with the invention, seen from behind,

Fig. 4 shows a schematic perspective view of an embodiment of the supply arrangement in accordance with the invention, seen from the front,

Fig. 5 shows a schematic view from above of a preferred embodiment of the supply arrangement in accordance with the invention,

Fig. 6 shows a partial vertical cross-sectional view along VI-VI in Fig 5, of the preferred embodiment,

Fig. 7 shows a plan view of a distributing device that may be used together with with the invention, and,

Fig. 8 shows a vertical cross-sectional view through the distributing device of Fig. 7. MODE(S) FOR CARRYING OUT THE INVENTION

In Fig. 1 there is shown a road finishing machine 1 , preferably provided with a sensor 10 for scanning the temperature of an asphalt pavement P directly after laying of the asphalt pavement. The sensor 10 preferably is in form of line scanner that measures the IR radiation. In the preferred embodiment, the line scanner 1 is connected to a quality measurement system as disclosed in WO2016198333, which is herewith introduced by way of reference.

Further the pavement machine has an inlet space 11 for supply of asphalt, e.g. from a truck (not shown). In the bottom of the inlet space 11 there is a belt conveyor 12 (e.g. belt conveyor or screw conveyor), or two parallel conveyors 12 that feed the asphalt to the screed 13 of the pavement machine, whereby asphalt is distributed to form a pavement P. The screed 13 distributes the asphalt widthwise and levels and shapes it, and it usually includes leveling arms, moldboard, end plates, burners, vibrators, and slope sensors and controls.

In Fig. 2, there is shown a pavement machine 1 of Fig. 1 provided with a supply arrangement 2 in accordance with the invention. Accordingly, the supply arrangement 2 is intended to be used in connection with already existing pavement machines 1 but may of course also be used in connection with new kind of pavement machines. As is evident from the following the supply arrangement 2 preferably is arranged with devices (see items 30, 45, 46) that will facilitate shifting of the supply arrangement 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 bearing arrangement 7, a transmission 5, and a motor 6 for enabling rotation of the rotary vessel 3. Below the rotary vessel 3 there may be a distributing device 9, shown in Figs. 7 and 8, for optimizing the distribution of asphalt supplied by the feeding arrangement/conveyor 12.

As shown in Figs. 3, 4 and 5 the rotary vessel 3 generally has the form of a truncated cone that has a substantially vertical rotation axis C and a larger opening at the top forming an inlet 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 kind of irregularities 32, providing a kind of engagement to the asphalt within the vessel 3 to safe guard that the asphalt follows the rotation of the vessel 3, to improve a mixing effect. In the preferred embodiment, these

irregularities 32 may for instance be formed by folding a plurality of valleys along vertical planes or by welding flat sub-plate members 33 to form corresponding valleys. In this manner, there is formed a kind of valleys 32 between plate members assisting in providing a kind of engagement to asphalt within the vessel 3. It is evident for the skilled person that many different kind of engagement members 32 may be used, as will be presented more in detail in relation to Fig 5. below.

In a preferred embodiment as indicated in Fig 3 and shown in Figs. 5 and 6, the vessel 3 is arranged with a feeding member 300 attached adjacent the outlet 31 of the vessel, to safe guard that the material also in connection with low fill levels in the vessel 3 will rotate together with the rotation of the vessel 3. The feeding member 300 preferably comprises at least one pushing member 301 that provides a feeding surfaces 301 A, that will push on the material to follow the rotation of the vessel 3 and thereby assist in providing the desired rotation of the material. More preferred there is arranged at least two pushing members 301 , by means of at least one plate extending along a chorda of the vessel 3.

As shown in Fig. 5 in one embodiment there is provided four pushing members 301 providing four feeding surfaces 301 A, by arranging four plates 306, 307, 308, 309, joined at the center C to form a cross member, i.e. having two perpendicular parts 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 301 A that will push on the material to follow the rotation of the vessel 3 and thereby assist in providing the desired rotation of the material. In an alternate embodiment the plates of the feeding member 300 may be shorter and have their inner ends attached to an annulus (not shown) or merely comprise one plate along a chosen chorda or comprise 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 Y to provide a sufficient feeding surface 301 A. In a preferred embodiment the height is in the range of 50-300 mm, more preferred 100-200 mm. Further the lower edge of a plate should preferably be arranged at a distance above the edge of the outlet 31 , e.g. in the range of 50-300 mm, which may provide further assistance in homogenization of the asphalt, i.e. by arranging for randomly distributing asphalt supplied 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 with skirt 34 that is rigidly attached to the frame 4 and that may provide protection and insulation. In many applications, as shown in Fig 6, it may be preferred to not use a skirt 34.

The transmission 5 includes an annular gear 50 that is rigidly connected to the rotary vessel 3 and in meshing engagement with a drive gear 51 driven by the motor 6.

The frame 4 may preferably include three connected base beams, i.e. two parallel side 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 forwardly extending frame part 47 carries lifting eyelets 45 or similar devices (also preferably provided at the top of the rotary vessel 3), a load exchanging member 46 and wall members 49A, 49B. Preferably the side beams 40 are length adjustable by arranging telescopically adjustable beam members 48, which may be adjusted to extend the length of the sides.

In Fig. 6 there is a detailed view of the rotary part of the transmission 5 and the bearing 7. As shown, the annular gear 50 has an inner side 70 that forms the rotary surface of the bearing 7, in radial sliding (lubricated) contact with the outer surface of a fixed bearing ring 71. Balls 72 may be used to take the axial load. The drive gear 51 interacts with the outwardly protruding teeth 52 of the annular gear 50. The annular gear 50 is fixed to a transmission ring welded onto the outer side of the rotary vessel 3. The fixed bearing ring 71 is fixed to bearing part 73, which in turn is fixed to the support beams 43. Further, Fig 5 shows that a plurality of feeding ribs 303 may be attached to the inner surface 304 of the vessel 3, which extend along vertical planes from a position adjacent 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 is provided a distributing device 9. As indicated in Figs. 7 and 8, the distributing device 9 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 preferably has a width W that substantially

corresponds to the diameter D of the outlet 31 of the vessel 3. The length thereof is preferably adapted to be a good fit within the paving machine 1. The distributing device 9 has two parallel outer frame members 90, 91 extending longitudinally in relation to the paving machine 1 , i.e. the feed direction of the conveyor 12. At least one dividing member 93, preferably in the form of a wall, is arranged transversely from one side to the other within the distributing device 9, i.e. from one longitudinal frame member 90 to the other 91. It may be advantageous to use a plurality of dividing walls 93, wherein preferably the dividing walls 93 are arranged with their upper edge in the same level, preferably substantially coinciding with the upper edge of the longitudinal frame members 90, 91. In the preferred embodiment the dividing walls 93 93A-93E have a different height h. At a most upstream position (with reference to the feed direction of the conveyor 12) there is a first dividing member 93A having the largest height, hi. In parallel therewith there are

positioned a plurality of further such dividing walls 93B-93E, wherein each dividing wall in the direction towards the discharge end of the conveyor the height h decreases for each dividing wall. In the shown example, there are positioned five such dividing walls 93A-93E, wherein each of said dividing walls is positioned such that it crosses at least a subsection of the circle defined by the outlet 31 from the vessel 3. Accordingly, the total distance between the five dividing walls in the longitudinal direction is substantially the same as or less than the diameter D of the outlet 31. Further, as is shown there is preferably a substantially proportional decrease of the height h in the direction of feeding, such that the first dividing wall 93A has a height hi that is 5 times the height hs of the final dividing wall 93E. The height hi of the first dividing wall 93A will be smaller than height FI of the frame members 90, 91 , such that there is created a gap g between the lower end thereof and 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 is arranged a rearrangement device 95. The rearrangement device 95 has a concave surface 95A directed“obliquely” against the flow of asphalt that is supplied by means of the conveyor 12, forming a kind of roof that is higher at the center than near the sides, so that the asphalt layer on leaving the distributing device 9 is cambered. The rearrangement device 95 will create a form of the bed of asphalt leaving it, such that it minimizes, preferably eliminates, slipping of parts of the bed of asphalt, e.g. by creating 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 into a paving machine 1 , preferably by lifting it into the supply space 11 by use of the lifting eyelets 45. The distributing device 9 may be positioned on top of the conveyor member/s 12 of the paving machine 1 before or afterward. In any case the rotary vessel 3 and its frame 4 are positioned on top of the distributing device 9 to be positioned as indicated in Fig. 6.

In operation, asphalt will be supplied into the rotary vessel 3 from above, e.g. by means of an intermediate feeder that is supplied from a truck tipping asphalt from its flatbed (not shown), i.e. in a conventional manner for supplying asphalt to the paving machine 1. Thanks to the rotation of the rotary vessel 3, the asphalt supplied will be thoroughly intermixed, whereby temperature differences that have appeared due to the transport and/or storage will be leveled-out. In a preferred manner then asphalt is supplied off-centered to the rotary vessel 3, i.e. onto the inner surface 304 of the rotary vessel, in order to possibly further improve intermixing of the asphalt in the rotary vessel. The conveyor 12 of the paving machine 1 continuously moves during operation and accordingly will bring along the asphalt A that is supplied on to it via the outlet 31 of the rotary vessel 3.

The distributing device 9 may provide for a further leveling out of the asphalt mixture by means of the dividing walls 93. A first volume will be supplied near the bottom of the distributing device 9 in connection with a first dividing wall 93A adjacent the 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 wall 93A and the second dividing wall 93B, etc., and moved by the conveyor 12 towards the outlet end 94 of the distributing device 9. At the outlet end 94 of the distributing device 9, a final rearrangement device 95 may be

provided, the rearrangement device 95 will create a form of the bed of asphalt leaving it, such that it minimizes, preferably eliminates, slipping of parts of the bed of asphalt, e.g. by creating sides that do not slope more than 45°. Further the rearrangement device 95 will create a counter pressure that is also beneficial. Thanks to the invention very much more evenly distributed asphalt will be supplied to the paving machine 1 , which will improve the quality of the asphalt.

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

The invention is not limited to what is defined above but may be varied within the scope of the claims. For instance, it is evident that a pavement machine 1 without sensor 10 and without a distributing device 9 may be used to achieve the basic advantages of the invention. Moreover, the skilled person realizes that in some applications in may be sufficient to use merely one dividing member 93 arranged transversely from one side to the other within the distributing device 9, and in others two or three or perhaps more than five. Further it is to be understood that the rearrangement device 95 may be positioned adjacent the outlet end 94 or anywhere between the outlet end 94 and the position for the outlet. Moreover, it is evident that many of the expression used are in no way limiting, e.g. that the relationship value may take other formats than the one exemplified above.