Patent Application
20090304446
1. Field of the Invention
The present invention relates to vibrating tampers and more particularly pertains to a new tamper assembly that is removably attached to an asphalt paver, bulldozer, cold patch truck or other equipment for tamping stone, dirt or the edges of asphalt.
2. Description of the Prior Art
The lifetime (e.g. durability) of asphalt road surfaces can be greatly enhanced by construction equipment and techniques that create tighter seals at asphalt seams. Tighter seals translate to a significant reduction in time, cost and resources used for road maintenance over the useful lifetime of the asphalt road surface. Various vibrating tampers used in the construction, earth moving and asphalt paving industries are known in the prior art and are used to create tighter asphalt seals.
As will be known to those skilled in the art, road paving is commonly accomplished by sequentially spreading, raking and rolling a top coat of asphalt along a prepared surface of crusher stone, base, binder material, and the like. A typical road width generally exceeds the width a typical roller, thus requiring several passes of the asphalt paver and roller to complete a particular asphalt road section. Seams are created between the various rolled sections and form a weak point in the surface that is particularly susceptible to deterioration. When water infiltrates into the asphalt at these seams, the pooled water in the seams freezes and expands during cold weather, disrupting and dislodging surrounding asphalt. This results in cracking and potholes.
Another common source of asphalt road deterioration is the nonuniform distribution of coarser particles across the peripheral surface of the asphalt material during the paving process. When the asphalt material is laid, the screed or wing of the asphalt paver causes these coarser particles to flow toward the outer edge of the asphalt material being laid. Over time, this aggregation of many coarser particles along the outer edge results in dislodging of these coarser particles; creating cracking, potholes and general road deterioration at the road edges. Thus, it is desirable to provide a device or assembly that prevents an outer edge aggregation of coarser asphalt particles during the paving process.
To create tight seams (that prevent the infiltration of water at the seams), various techniques have been used in the prior art. The most common technique is rolling (e.g. compacting) the seams. This rolling or compacting process may be enhanced with the application of heat and/or fluids to bring the asphalt to an optimum consistency and/or temperature for compacting. However, this process has well known drawbacks. In the prior art, an asphalt paver first lays the asphalt at a temperature that is optimal for spreading and compaction. Then, in a second process, a roller is applied to the asphalt for compaction. The independent roller equipment follows the asphalt paver at a distance of about 400-1600 feet (487.7 meters), generally around 500 feet (152.4 meters), exposing the asphalt surface to the environment for a period of time and cooling the asphalt material. Thus, when the roller compacts the asphalt material, the asphalt material has already cooled to a temperature below the optimal range required for the greatest compaction. Thus, the compaction and seal are not ideal, that is, not as tight as possible and having excessive voids disposed throughout.
To facilitate a more uniform distribution of coarser particles along the peripheral surface of the asphalt material, various techniques have been used in the prior art. The most common technique involves a worker standing at the side of the seam manually sweeping the coarser particles back toward the center of the asphalt surface with a broom or rake. The worker brushes off the excess at the seam and pushes the excess toward the mat “hot pass” section such that the fines remain at the edge and the coarser rocks and particles are spread inwardly toward the mat where they compacted into the surface. This is a labor intensive and costly solution that produces inconsistent results.
Prior art attempts to propose a solution for these known limitations and drawbacks in the prior art include an adjustable shoe such as the Cedarapids Company model 361 or 362 asphalt paver that enables the screed to lay correct the amount of asphalt and keep the asphalt in place. However, these devices are known to cause sharp edges, inconsistent surfaces and pocks. Additionally, this equipment causes friction and drag on the asphalt paver.
The inventor invented a tamping device disclosed in U.S. Pat. No. 7,316,524. However, this portable hand held tamper is not suited to large asphalt paving and road construction projects. The present invention improves upon this technology by providing an assembly configured for attachment to a vehicle and capable of utilizing the hydraulics and fuel supply already available on the vehicle.
While these devices fulfill their respective, particular objectives and requirements, the need remains for a device or an assembly that is removably and adjustably affixed to an asphalt paver (or other equipment) that comprises a tamper having off centered weights that are rotated to create the vibration. While some of the prior art devices have gained popularity, they have not been successful in creating the necessary compaction to eliminate or minimize water infiltration at the seams. They have also not been successful in uniformly distributing the asphalt particles across the asphalt surface to eliminate or minimize aggregation of these coarser particles at the outer edges. They also have not been successful in applying the compacting forces while the asphalt is at optimal temperature ranges.
It is desirable to design a device or assembly that is compatible with the prior art asphalt paving and compacting devices, improving upon their functionality and eliminating one or more of their limitations. The present invention fulfills this need and others.
The present invention meets the needs presented above by generally comprising a tamper assembly for tamping asphalt or stone placed on a surface, said assembly comprising: a motor being coupled to a transfer shaft, said motor rotating said transfer shaft when said motor is actuated; a plurality of eccentric weights being coupled to said transfer shaft; a first attachment bar being rotatably coupled (via a ball joint) to a mounting bracket at a proximal end and a ball joint on a first support on a distal end of said first attachment bar; a second attachment bar being rotatably coupled (via a ball joint) to said mounting bracket at a proximal end and a ball joint of a second support on a distal end of said second attachment bar; said first attachment bar and said second attachment bar being adjustable with respect to said tamping foot via ball joints; said mounting bracket being configured for removable attachment to an asphalt paver; said first support and said second support being coupled to said tamping foot via ball joints; and a tamping foot being rotatably coupled to said transfer shaft, said tamping foot vibrating when said motor is actuated to tamp the asphalt or the stone and said tamping foot is drawn across the asphalt or the stone.
In one preferred embodiment, the device or assembly incorporates a liquid supply assembly to supply liquid to the screed prior to tamping to inhibit the tamper components from sticking to the asphalt. In another preferred embodiment, the device or assembly incorporates a heat source to apply heat to the asphalt surface, thereby increasing the temperature of the asphalt material, prior to tamping. In another preferred embodiment, the assembly or device incorporates a rake to distribute the asphalt particles in a manner that prevents the aggregation of coarser particles along the outer edge during the paving process.
It is an object of the present invention to provide a tamper assembly that is removably attached to an asphalt paver, bulldozer, cold patch truck or other equipment for tamping stone, dirt or the edges of asphalt.
It is an object of the present invention to provide an assembly that rakes off excess seam material or high spots prior to compaction.
It is an object of the present invention to provide an assembly that supplies liquid to the screed prior to tamping to inhibit the tamper components from sticking to the asphalt.
It is an object of the present invention to provide an assembly that applies heat to the asphalt surface, thereby increasing the temperature of the asphalt material, prior to tamping.
It is an object of the present invention to provide an assembly that distributes the asphalt particles in a manner that prevents the aggregation of coarser particles along the outer edge during the paving process.
It is a further object of the present invention to provide an assembly that preheats seam material prior to compacting and sealing the seam.
It is a further object of the present invention to provide an assembly that seals an asphalt seam at proper temperature.
It is a further object of the present invention to provide an assembly that seals an asphalt seam through the vibration of eccentric weights.
It is a further object of the present invention to provide an assembly that creates a smoothing effect across a seam during the seam sealing process.
Whereas there may be many embodiments of the present invention, each embodiment may meet one or more of the foregoing recited objects in any combination. It is not intended that each embodiment will necessarily meet each objective.
Thus, having broadly outlined the more important features of the present invention in order that the detailed description thereof may be better understood, and that the present contribution to the art may be better appreciated, there are, of course, additional features of the present invention that will be described herein and will form a part of the subject matter of the claims appended to this specification.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The present invention is capable of other embodiments and of being practiced and carried out in various ways. Also it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The novel tamping assembly disclosed herein may be used with conventional equipment, and in particular, with an asphalt paver, to optimize the conditions for asphalt paving and improve the final asphalt product. The assembly automates labor intensive manual functions, offering a significant labor savings.
By preventing an outer edge aggregation of coarser asphalt particles, there is a more uniform distribution of coarser particles across the peripheral surface of the asphalt material laid by the paver, and especially in the “hot pass” portion. Uniformly distributing the asphalt particles across the asphalt surface eliminates or minimizes aggregation of coarser particles at the outer edges.
By minimizing the time exposure of the asphalt surface to cooling, the roller compacts the asphalt material at temperatures required for the greatest compaction. This creates the necessary compaction to minimize, or even eliminate, voids in the compacted asphalt, and thus, minimizing or eliminating water infiltration at the seams.
This tamping assembly is mounted behind the paver, eliminating the friction and drag “skis” typically have on the asphalt paver. It is removable and adjustable, offering great flexibility to the user.
The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings, in which like numerals refer to like elements, and wherein:
The drawings are not to scale, in fact, some aspects have been emphasized for a better illustration and understanding of the written description.
Referring to
Referring to
It is to be understood that the mounting unit illustrated in the embodiment depicted in
The mounting points of the tamper assembly 2 to the asphalt paver 14 are controlled by the tamping foot 16, the length of the attachment bars 6, 6A and the location of the edge of the seal 12 being pinched. Preferably, as depicted in
In an alternative embodiment (not depicted), mounting is in the rear center of the screed unit 13. This central position allows the tamper assembly 2 to be disposed over seams 12 to the right or left of the asphalt paver 14 without having to remount the entire tamper assembly 2.
Referring to
As depicted in
In use, the hydraulic motor 74 is actuated to rotate the transfer shaft 70. As the transfer shaft 70 is rotated the transfer shaft 70 is rotated which rotates eccentric weights 64 and 66. The off center orientation of the eccentric weights 64, 66 creates a vibration in the tamping foot 16 and vibrates the tamping foot 16 which is positioned against the asphalt or the stone. The vibration of the tamping foot 16 tamps the asphalt or stone.
Referring to
Incorporation of the hydraulics and fuel supply available on the vehicle 14 allows the tamping assembly to be lighter in weight and mechanically less complex. By way of example, an apparatus that used mechanical linkages to power the eccentric weights would require more complex linkages and gears, requiring more physical space and preventing the compact profile and footprint of the present invention. This may cause obstructions with existing component parts (e.g. screed 13) of the vehicle 14 and make a universally attachable assembly 2 difficult to configure. The present invention addresses these limitations and provides a solution that is highly adaptable and easy to manufacture.
Coupler 72 transfers the power from the hydraulic motor 74 to the transfer shaft 70. Eccentric weights 64 and 66 are mounted about transfer shaft 70 and create the vibration of the tamper assembly 2. A-frame bracket 62 couples attachment bar 6 to the tamping foot 16 via ball joint 22. Two pillow block bearings 68 (one hidden from view behind A-frame bracket 62 but see
Ball joint 24 couples a second attachment bar 6A to support 18, 20 disposed on the tamping foot 16. One support 18, 20 is disposed on either side of the tamping foot 16 to facilitate mounting of the tamper assembly 2 along a seam on both the right and left sides of the asphalt paver 14. The axis of each ball joint 22, 24 is perpendicular with respect to the other and the centerpoints of ball joints 22, 24 are disposed at a distance 60 from one another of from about 8 inches (about 20.32 centimeters) to about 10 inches (about 25.4 centimeters) from one another. The centerpoint of ball joint 22 is disposed at a distance 48 from the rear peripheral edge of the tamping foot 16 and a distance 44 from the both side peripheral edges of the tamping foot 16. A similar configuration is provided for support 20 on the right side of the tamping assembly 2.
Turnbuckle 4, 4A and attachment bar 6, 6A adjustably position the tamper assembly 2 about the asphalt surface (or ground, soil, sand, clay, stone, etc.). Preferably, and as illustrated and discussed more fully with respect to
Compaction by an asphalt paver 14 generally ranges from about 80 percent (either vibrating plate or vibrating tamper bar) to about 92 percent (both vibrating plate or vibrating tamper bar). The final compaction layer is generally performed by rollers (steel or tire). The final density of the asphalt has a huge effect on the mechanical properties of the asphalt, especially on resistance against permanent deformation. Thus, compaction is a critical process for ensuring long term durability of the road. Compaction aims to reduce volume and increase density. Poor compaction during construction results in post compaction by vehicles traveling over the road and unevenness in the road surface over time. Asphalt compaction is greatest with a combination of static compaction (e.g. with a road roller) and vibratory compaction (e.g. with a vibrating tamper). The tamper assembly 2 provides vibratory compaction that may be followed by static compaction via a roller.
Compaction is optimum when the asphalt temperature is sufficiently high because the viscosity of the bitumen is sufficiently low. Compaction is severely impeded at temperatures below 70 degrees Celsius (158 degree Fahrenheit). Proper compaction of seams requires both preventing loss of heat from the newly laid asphalt from the hot pass and preheating the previously laid asphalt on the cold pass and/or underlayer. The tamper assembly 2 provides a device that does both, offering the best possible seam and mat compaction results. Preventing loss of heat from the newly laid asphalt is accomplished by the close proximity of the tamper unit to the vehicle 14, thereby minimizing heat loss from exposure to ambient air. Preheating the previously laid asphalt on the cold pass is accomplished by the flame burner system 88 (flame throwers). The flame burner system 88 (flame throwers) also provide a means of heating the underlayer to enhance adhesion or newly laid asphalt should heat loss have occurred.
Maintaining proper asphalt temperature is important to the overall results of an asphalt paving project. During the precompaction by the asphalt paver 14, the asphalt material still has a very high temperature and can thus be compacted easily. The asphalt material is preferably in the range of from about 130 to about 150 degrees Celsius (about 266 to about 302 degree Fahrenheit) when it enters the hopper. Preferably the newly laid asphalt material has not cooled more than about 5 degrees Celsius (about 41 degree Fahrenheit) after precompaction by the screed unit 13. Preferably, the temperature of the asphalt during compaction by the tamper assembly 2 is from about 250 to about 290 degrees Fahrenheit (about 121.1 to about 143.3 degree Celsius) when the seam is sealed. Pinching the seams at these temperatures increases the life expectancy of the asphalt road by as much as 50%.
Laying an asphalt road requires several steps: transporting the premanufactured asphalt mixture to the work site by truck, laying and profiling the asphalt material with an asphalt paver 14, compacting the asphalt and final treatment of the surface. Compacting generally has two components: precompacting by the screed 13 of the asphalt paver 14 and compacting by a static compactor or vibratory compactor. Seams are generally compacted with two rollers: one on the old “cold” pass and one on the new “hot” pass. Preferably, these rollers work together to push asphalt toward the center as the seams are pinched.
As will be demonstrated, the tamper assembly 2 functions to “pinch” the seam by vibratory compaction as it travels behind the asphalt paver 14. Thus, one roller (the roller on the cold side) can be dispensed with in a typical paving operation. As such, the paving process is more economical and efficient—one less machine, less fuel for operation, and one less machine operator required in the paving process. In some contexts, additional economies are realized when additional workers (such as wingmen and/or manual rakers) are dispensed with. Applicant estimates that savings range from about 10% to about 30% for a given job, with 15% being the average savings for a typical job.
Referring to
Referring to
A screed unit 13 is attached to the rear of the asphalt paver 14 and generally contains a vertically vibrating tamper bar and/or a wide vibrating plate, leveling arms 15 and a screed plate. The screed unit 13 initially compacts the asphalt to create an asphalt layer with a uniform thickness. The vibrating plate or vibrating tamper bar generally contains a heating system. The width of the screed unit 13 (so the spreading width of the asphalt) generally varies from about 2 to about 12 meters (about 6.562 to about 39.37 feet). Adding or removing extension pieces or built-in hydraulic extensions can extend the width by an additional 20 feet (6.096 meters) or more. The height of the screed unit 13 is generally controlled by a conducting wire at both sides of the road under construction (typical for asphalt base and binder layers), a ski or a shoe connected to the asphalt paver and from which the height level is imported by the asphalt paver (typical for upper asphalt layer). Thus, as will be discussed in greater detail below, it is important that the size, profile and mounting position of the tamping assembly 2 be configured to avoid interference with these typical pieces/components of equipment, thus creating the most universal range of equipment upon which this aftermarket accessory 2 can be removably attached.
Referring to
It is to be understood that a separate tamper assembly unit is not essential, but that the various components and functions of the tamper assembly can also be incorporated in other pieces of equipment. Such embodiments are considered within the scope of the present invention.
Referring to
Referring to
Referring to
In an alternative embodiment (not depicted), a supply tank stores the liquid. In one embodiment, two or more supply tanks are coupled to the tamping foot 16. In one embodiment with two supply tanks, fuel and lubricant are stored in each tank respectively. As will be apparent, substantially similar or duplicate liquid supply systems may be provided for embodiments with multiple supply tanks.
A valve (not depicted) is coupled to each spray nozzle 86 and burner system 88 (flame thrower) and in fluid communication with the supply. The valves control a flow of the fluid from the supply when the valves are actuated. In the embodiment depicted, there are at least four valves.
When activated, the burner system 88 (flame thrower) applies heat to the cooled asphalt prior to coming into contact with the tamper assembly 2. The cooled asphalt material, commonly known as spam, is thus preheated prior to compaction. This preheating process brings the asphalt material to an optimum temperature range for maximum compaction and adhesion. Preferably, the burner system 88 heats the spam to a temperature of from about 100 degrees Fahrenheit (about 37.78 degree Celsius) to about 300 degrees Fahrenheit (about 148.9 degree Celsius), preferably from about 100 degrees Fahrenheit (about 37.78 degree Celsius) to about 150 degrees Fahrenheit (about 65.56 degree Celsius). As will be known to those skilled in the art, the desired temperature is dependent upon a number of factors, including ambient air temperature, ground temperature, and the like. The cooler the ambient or ground temperature, the greater the desired temperature increase in the spam to bring it to a pliable consistency for compacting and sealing. Preferably, the asphalt, an in particular, a prior seam 12 of a cold pass or underlayer, is heated by the burner system 88 (flame throwers) to a point when the asphalt transforms to a glossy black color, indicating that the tar is sufficiently loose enough to allow for proper compaction and adhesion. Adhesion of the newly laid asphalt is enhanced when the tar of the underlayer (e.g., first pass, base or binder) to which it is applied is sufficiently loose and pliable.
When activated, a lubricant sprayer 86 sprays a light coating or film of lubricant (e.g. fuel oil) on and in front of the base of the tamping foot 16 and/or screed 3 prior to coming into contact with the tamper assembly 2. This lubricant prevents the bottom of the tamper assembly 2 from sticking to the heated asphalt material and causing sheering of the newly laid asphalt. This is most often used during the early stages of a paving operation during a given time period before the screed heats up to a temperature sufficient to preventing sticking.
A lubricant sprayer 86 is coupled to the fuel line 84 of the tamping foot 16 and extends around a perimeter of the tamping foot 16. The lubricant sprayer 86 is in fluid communication with the valve (not depicted). The lubricant sprayer 86 sprays the liquid onto the screed and/or asphalt around the tamping foot 16 when the valve is actuated to allow the liquid to flow from the supply.
Referring to
Referring to the embodiment depicted in
Referring to
The peripheral edge 80 of the screed 3 of the tamping foot 16 preferably is chamfered or rounded along its exterior surface. It is formed with a slight curve or contour (also known as a “bull nose”) or rounded profile such that there are no sharp edges along the lower edges of the tamping foot 16. The angle of the curve is not critical but can be selected to accomplish the purpose of minimizing stress, absorbing shock and preventing breakage at this juncture, in particular, that caused when the tamping foot 16 contacts the asphalt surface during use. It preferably has a natural 45 degree radius curve.
Referring to
Lute head has a cross sectional shape 82 comprising a complex convex irregular octagon and a height 106 of from about 4 inches (about 10.16 centimeters) to about 6 inches (about 15.24 centimeters).
Referring to
Referring to
During use, the tamper assembly 2 is preferably disposed over the seam 12 such that about three fourths of the tamper assembly 2 contacts the cold pass 122 and one quarter contacts the hot pass 120. Put another way, the exterior of side 118 is disposed over the asphalt a distance of about 0.25 of the width 42 from seam 12 (thus from about 2 to about 3 inches (about 5.08 to about 7.62 centimeters) from the seam 12). The tamper assembly 2 is towed in the forward direction 112 behind the asphalt paver 14
The tamper assembly 2 may be configured for attachment to an asphalt paver 14, a bulldozer, a cold patch truck, and the like. While it is anticipated that the tamper assembly 2 will most frequently be used on projects with a single asphalt paver, it conceivably may be used with tandem passes with two asphalt pavers as well. It 2 may be configured for attachment to a wing extender, a screed extender or various other component portions of the asphalt paving machine 14. It is important that the tamper assembly 2 be attached in a manner that does not interfere with other component parts of the screed unit 13. Generally, other components of the screed unit 13 or attachments thereto are disposed outwardly a distance of about 24 inches (about 60.96 centimeters) (unless there is oncoming traffic or tandem paver units) and are never disposed over the seam. Thus, the compact profile and width 42 of the tamper assembly 2 allow it to easily be mounted such that is traverses over the seam without interference with operative parts of the machinery.
The tamping foot 16 may be formed of one or more materials. The deck 5 may be formed of casted aluminum or iron. The screed 3 may be made of the same casted aluminum or iron, or alternatively, be formed of high tensile steel, high strength aluminum or aluminum alloys, or titanium. Other materials known to those skilled in the art are suitably adapted to the present invention.
The tamper assembly 2 may also be used in trenchwork (ditches) to compact soil or stone after utility facilities or drainage pipe is laid. As will be apparent, the flame throwers and lubricant sprayers would not be incorporated in this application.
With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.
Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
This application claims the benefit of provisional patent application U.S. Ser. No. 61/058,635 entitled “Tamper Assembly” filed by Kevin Pikuet on Jun. 4, 2008.
| Number | Date | Country | |
|---|---|---|---|
| 61058635 | Jun 2008 | US |
