WO2012144986A1

WO2012144986A1 - Asphalt pavement constructing machine and method of operation

Info

Publication number: WO2012144986A1
Application number: PCT/US2011/032970
Authority: WO
Inventors: John R. Haupt; Michael P. Macdonald
Original assignee: Volvo Construction Equipment Ab
Priority date: 2011-04-19
Filing date: 2011-04-19
Publication date: 2012-10-26
Also published as: EP2699732B1; EP2699732A4; CN102985617A; EP2699732A1; US20140119827A1

Abstract

The present invention relates to an asphalt pavement constructing machine and a method for operating an asphalt pavement constructing machine provided with an asphalt compacting surface for compacting asphalt mix on a paving surface during an asphalt pavement formation operation. At least one exciter is provided that vibrates the compacting surface at one or more frequencies selected to prevent the asphalt mix from adhering to the compacting surface.

Description

ASPHALT PA EMENT CONSTRUCTING MACHINE AND METHOD OF

OPERATION

FIELD OF THE INVENTION

The present invention relates to asphalt pavement constructing machines provided with at least one compacting surface vibrated at one or more frequencies selected to prevent asphalt adhering to the compacting surface.

BACKGROUND OF THE IN VENTION

The formation of asphalt pavement typically involves a number of asphalt pavement constructing machines. An asphalt paver typically receives, deposits, and performs at least a partial compaction of the asphalt mix to form a freshly laid asphalt pavement. After initial compaction by the asphalt paver, a compactor, such as, a roller or drum compactor, is typically used for final compaction and finishing of the freshly laid asphalt pavement.

During both lay ing and compaction, adherence of asphalt to the compacting surfaces of the paver and/or compactor may damage the asphaii pavement and generate surface impressions in the top surface of the pavement as the asphalt is compacted, thus, leading to costly repair and delays for the paving contractor. Accordingly, systems have been devised to prevent this occurrence.

With respect to pavers, the current practice for preventing adherence of asphalt involves heating the compacting surface(s), which is typic ally located on the underside of a screed (or screed plate), to several hundred degrees Fahrenheit. Since it is difficult to heat the screed uniformly, often times the uneven heating will cause the compacting surface to deform, which, in turn, results m an uneven contour of the asphalt pavement and a top suriace that lias slight depressions. Additionally, large amounts of energy are required for the screed to be preheated, which can take as long as 20 minutes before work can be performed.

Furthermore, since the top of the screed typically functions as a working platform for workers, the thermal radiation generated during this process produces an uncomfortably hot working environment.

With respect to compactors, the current practice for preventing adherence of asphalt involves water spray systems. Scrapers are also used, but only to remove asphalt after it adheres to the compacting surfaces of the roller and, accordingly, after impressions have already been left in the top surface of the pavement. In addition to generating undesirable cooling of the asphaii pavement, water spray systems are large and bulky. In order to be effective, the water must coat the entire compacting surface of the roller, which ma be difficult for a number of reasons, including wind and clogged nozzles. This system also requires numerous components, including large tanks of water that must constantly be refilled, filters that must be checked, and pumps that must operate correctly at all times. In order to ensure complete water coverage frequent inspection and repair is common.

The present invention relates to asphalt pavement constructing machines provided with a compacting surface vibrated at one or more frequencies selected to prevent asphait mix adhering to the compacting surface.

SUMMARY OF THE INVENTION

According to one aspect of the present in vention, an asphalt pavement constructing machine comprises an asphalt compacting surface and at least one exciter that vibrates the compacting surface at one or more .frequencies selected to prevent asphalt adhering to the compacting surface.

According to another aspect of the present inv ention, a method for operating an asphait pavement constructing machine provided with a compacting surface comprises the steps of using the compacting surface to compact asphalt mix on a pa ving surface during an asphalt pavement formation operation and using at least one exciter to vibrate the compacting surface at one or more frequencies selected to prevent the asphalt mix from adhering to the compacting surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of an asphalt pavement constructing machine according to one embodiment.

FIG. 2 illustrates a compacting surface according to one embodiment.

FIG, 3 illustrates side view of an asphalt pavement constructing machine according to another embodiment.

FIG. 4 illustrates compacting surfaces according to one embodiment.

DETAILED DESCRIFTON OF THE INVENTION

Turning now to FIG. 1, an asphalt pavement constructing machine according to one embodiment is depicted. As shown, the asphait pavement constructing machine is a paver 15 configured to receive, deposit, and partially compact asphalt mix 5 and form an asphalt pavement 7 on top of a paving surface 6. As shown therein the pa ver 15 may be provided with an asphalt hopper 20. an asphalt conveyor 25, an asphalt spreader 30, a screed 40 supported by tow arms, as at 43, and an asphalt compacting surface 45.

Those of ordinary skill i the art will appreciate that during a paving operation, asphalt mix 5 is typicaily loaded onto the paver 15 and temporarily held in an asphait hopper, such as asphait hopper 20. Those of ordinary skilled in the art will also appreciate that during a paving operation, one or more asphalt conveyors, such as asphalt conveyor 25, typically transport the asphalt mix 5 from the asphalt hopper 20 and deposit it. on a paving surface, such as paving surface 6, whereat one or more asphalt spreaders, such as asphalt spreader 30, which may be in the form of one or more augers, as shown, spread the asphalt mix 5 on the paving surface 6 m a direction that is lateral with respect to a direction of travel of the paver 15. Those of ordinary skill in the art will appreciate that the asphalt mix 5 is compacted after the asphalt mix 5 is deposited on the paving surface 6 and laterally distributed on the paving surface 6 by the asphalt spreader 30.

As shown in FIG. 1 , the paver 15 is provided with at least one asphalt compacting surface, such as for example, asphalt compacting surface 45, which compacts the asphalt mix 5 to form an asphalt pavement 7 on the paving surface 6. As shown in the present embodiment, the asphalt compacting surface 45 is a generally flat surface located on the underside 41 of a screed 40, which may be provided with a work platform 42 whereupon workers may stand. Those of ordinary skill in the art will appreciate that as the paver 1 travels along the paving surface 6, for example by a track assembly or wheels, as at 16, the asphalt compacting surface 45 exerts a compressive force on the deposited asphalt mix 5 to smooth and at least partially compact the asphalt mix 5, whereby a freshly laid asphalt- pavement 7 is formed on the paving surface 6.

According to one aspect of the present embodiment, the asphalt compac ting surface 45 is vibrated at one or more frequencies. According to another aspect of the present embodiment, the asphalt compacting surface 40 is vibrated at one or more frequencies to prevent asphalt adhering to the asphalt compacting surface 45 as the asphalt mix 5 is compacted by the asphalt compacting surface 45.

Turning now to FIGS. 1 and 2, as shown, the paver 15 includes one or more exciters 50, including, for example electromagnetic, as at 50a (F G. 2) piezoelectric, as at 50a' (FIG. 4), or hydraulic exciters, as at 50a" (FIG. 4), that vibrate the asphalt compacting surface 45 atone or more frequencies selected to prevent asphalt adhering to the asphalt compacting surface 45 as the asphalt mix 5 is contacted by the asphalt compacting surface 45. Those of ordinar ski ll in the art will appreciate that i t is within the scope of the present invention to utilize any number of exciters 50 and to distribute the exciters with respect- to the asphalt compacting surface 45 in any manner that excites the asphalt compacting surface 45 in a manner that prevents asphalt from adhering to the asphalt compacting surface 45. In FIGS. 1 and 2, for example, a plurality of exciters 50 are shown located within the screed 40, whereby the asphalt compacting surface 45 is vibrated indirectly by the exciters 50. As shown in FIG. 2, one or more electronics 100 may be used to dri ve the exciters 50 and control the frequency of vibrations) generated by the exci ters 50.

Turning now to FIG. 3, an asphalt pavement constructing machine according to another embodiment is depicted. As shown therein, the asphalt pavement constructing machine is a rolling compactor 60 that may be used for final compaction of pavement 7. As shown in FIG. 3, the roiling compactor 60 is provided with first and second .rollers 61, 62. According to one aspect of the present invention, the rollers 61 , 62 propel the rolling compactor 60 along the pa vement 7. According to another aspect of the present

embodiment, the rollers 61 , 62 ar configured to perform a final compaction of the pa vement 7, According to yet another aspect of the present embodiment, the rollers 61 , 62 may be used to provide the pavement 7 with a generally smooth .finished top surface 7a,

As shown in FIG. 3, the rolling compactor is provided with asphalt compacting surfaces 63, 64 that are cylindrical in shape and located on the outer circumferential surface of the rollers 61 , 62 that propel the rolling compactor 60 along the pavement 7. Those of ordinary skill in the art will appreciate that as the rollers 61, 62 propel the rolling compactor 60 along the pavement 7 that the asphalt compacting surfaces 63, 64 exert a heavy compacting force on the pavement 7. Those of ordinary skill in the art will appreciate that the heavy compacting force exerted by the asphalt compacting surfaces 63, 64 compacts the pavement 7. Those of ordinary skill in the art will appreciate that the heavy compacting force exerted by the asphalt compacting surfaces 63, 64 preferably provide the pavement 7 with a generally smooth finished top surface 7a.

According to one aspect of the present embodiment, the asphalt compacting surfaces 63, 64 are vibrated at one or more frequencies. According to another aspect of the present embodiment, the asphalt compacting surfaces 63, 64 are vibrated at one or more frequencies to prevent asphalt adhering to the asplialt compacting surfaces 63, 64 as the pavement 7 is compacted by the asphalt compacting surfaces 63, 64.

Turning now back to FIG. 3, as sh wn the rolling compactor 60 includes a plurality of exciters 50\ including, for example electromagnetic, as at 50a (FIG. 2) piezoelectric, as at 50a⁵ (FIG. 4), or hydraulic exciters, as at 50a" (FIG. 4), that vibrate the asphalt compacting surfaces 63, 64 at one or more frequencies selected to prevent asphalt adhering to the asphalt compacting surfaces 63, 64 as the freshly laid pavement 7' is compacted by the asphalt compacting surfaces 63, 64. Those of ordinary skill in the art will appreciate that it is within the scope of the present invention to utilize any number of exc iters 50' and to distribute the exciters with respect to the asplialt compacting surfaces 63, 64 in any manner that excites the asphalt compacting surfaces 63. 64. In FIGS. 3 and , for example, a plurality of exciters 50' are shown located within the rollers 63 , 62, whereby the asphalt compacting surfaces 63, 64 are vibrated indirectly by the exciters 50, such as. for example, by placing the exciters 50 in direct contact with an inner cylindrical surface 61 a, 62a of the rollers 61, 62, As shown in FIG. 2, one or more electronics 100' may be used to drive the exciters 50' and control the frequency of vihration(s) generated by the exciters 50\

Ad vantageously, by employing vibrations at frequencies in excess of the frequencies used for compacting efficiency, i.e. frequencies in excess of about 70 Hz, compaction efficiency will not be degraded. While those of ordinary skill in the art will apprecia te that an optimal frequenc may be deduced from empirical observation, according to one aspect of the present embodiments the frequency vibration may be substantially equal to or greater than about 100 Hz. According to yet another aspect of the present embodiments, the frequency vibration may be substantially equal to or greater than about 1 kHz. According to another aspect of the present embodiments the frequency of vibration may be in the ultrasonic range and substantially equal to or greater than about 20 kHz.

Ad vantageously, the principals of the aforementioned embodiments may be utilized in conjunction with currently known systems, i.e. heating, scrapers, as at 80. 81 (FIG. 3), or water systems, for preventing asphalt adherence or may obviate the use of one or more currently known systems. Advantageously, by controlling the frequency of vibration, the adherence of asphalt to the asphalt compacting surfaces on asphalt pavement constructing machines, including, for example, the asphalt compacting surface 45 on paver 15 or asphalt compacting surfaces 63, 64 on the rolling compactor 60, may be prevented

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by th e inventors to be within the scope of the invention. The present description depicts specific examples to teach thos skilled in the art how to make and use the best mode of the invention. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those of ordinary skill in the art will also appreciate that some conventional aspects have been simplified or omitted.

Persons skilled in the art will recognize that certain elements of the above-described embodiments and examples may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the in vention. It will also be apparent to those of ordinary skill in the ar that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the invention. Thus, although specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. Accordingly, the scope of the invention is determined from the appended claims and equivalents thereof.

Claims

WE CLAIM:

1. An aspiiait pavement constructing machine, comprising:

an asphalt compacting surface; and

at least one exciter that vibrates the compacting surface at one or more frequencies selected to prevent asphalt adhering to the compacting surface.

2. The asphalt pavement constructing machine according to ciairn 1, wherein:

the asphalt compacting machine is a rolling compactor provided with the asphalt compacting surface a d another asphalt compacting surface;

at least one other exciter vibrates the another compacting surface at an frequency that prevents asphalt mix adhering to the another compacting surface; and

the asphalt compacting surfaces are cylindrical and located on first and second rollers that propel the rolling compactor.

3. The asphalt pavement constructing machine according to claim 1, wherein:

the asphalt compacting machine is an asphalt paver provided with an asphalt hopper, an asphalt conveyor, an asphalt spreader, and a screed; and the asphalt compacting surface is a generally flat surface located on the underside of the screed.

4. The asphalt pavement constructing machine according to claim 1 , wherein the at least one exciter is a piezoelectric exciter.

5. The asphalt pavement constructing machine according to claim 1, wherein the at least one exciter is an electromagnetic exciter.

6. The asphalt pavement constructing machine according to claim 1 , wherein the at least one exciter is a hydraulic exciter.

7. A method for operating an asphalt pavement constructing machine provided with a compacting surface, the method comprising the steps of: using the compacting surface to compact asphalt mix on a paving surface during an asphalt pavement formation operation; and

using at least one exciter to vibrate the compacting surface at one or more frequencies selected to prevent the asphalt mix from adhering to the compacting surface,

8. The method according to claim 7, wherein:

the asphalt compacting machine is a roiling compactor provided with the asphalt compacting surface and another asphalt compacting surface;

the asphalt compacting surfaces are cylindrical and located on first and second rollers mat propel the rolling compactor; and

the method further comprising the step of using at least one other exciter to vibrate the another compacting surface at one or more frequencies selected to prevent asphalt mix adhering to the another compacting surface.

9. The method according to claim 7, wherein the asphalt compacting machine is a paver provided with an asphalt hopper, an asphalt conveyor, an asphalt spreader, and a screed and the asphalt compacting surface is a generally fl t surface located on the underside of the screed, the method further comprising the steps of:

using the asphalt hopper to receive asphalt mix;

using the conveyor to deliver the asphalt mix to the auger;

using the auger to spread the asphalt mix on a paving surface; and using the compacting surface to compact the asphalt mix, whereby an asphalt pavement is provided on the paving surface.

10. The method according to claim 7, wherein the at least one exciter is a piezoelectric exciter. i 1. The method according to claim 7, wherein the at least one exciter is an electromagnetic exciter.

The method according to claim 7, wherein the at least one exciter is a hydrauli