Paving of a roadway with asphalt material is generally carried out by a paving machine that is supplied with asphalt materials by a number of supply trucks and/or a material transfer vehicle. The paving machine is self-propelled and driven by a wheeled or tracked drive system. In a common type of paving machine, an integral hopper is located at the front end of the machine to receive asphalt material from a truck or material transfer vehicle, and a conveyor system typically comprised of one or more slat conveyors located below the hopper transfers the asphalt material from the hopper to a transverse distributing auger that is mounted near the rear of the machine. The asphalt material is deposited onto and across the roadway or other surface to be paved by the distributing auger. A floating screed located at the rear end of the machine behind the distributing auger compacts the asphalt material and forms the asphalt mat.
Because paving machines are often supplied with asphalt materials by dump trucks, the front wall of a typical integral hopper is low enough to allow a dump truck to dump directly into the hopper. Although the sidewalls of an integral hopper are generally higher than the front wall, the front wall height of the integral hopper is a limiting factor in hopper capacity. However, when the paving machine is supplied with asphalt materials using a material transfer vehicle which drops asphalt into the hopper from a higher point (than a dump truck), the truck-loading front wall limitation is removed. Hopper inserts are known to be installed in the integral hopper of the paving machine for increasing the capacity of the machine, especially when it is to be supplied with asphalt materials by a material transfer vehicle.
Asphalt material is comprised of an asphaltic binder and aggregates of various sizes, including both coarse and fine aggregate materials. When asphalt material is properly produced in an asphalt production plant, it is generally homogeneous in the sense that the various aggregate sizes are evenly distributed throughout the mixture. However, paving is almost always carried out some distance from the production plant. Consequently, it is frequently necessary to transport the asphalt material from its place of origin to a paving machine at the paving site. Typically, the asphalt material is transported in dump trucks, and the loading of such material into the dump beds is accomplished by dropping the material from an overhead hopper or silo into the truck bed. Such loading operations, as well as the vibrations and jostling associated with vehicular transport tend to separate the asphalt materials into coarse and fine fractions in the truck bed. Furthermore, the time of transport tends to cause the asphalt material on the top and sides of the load in the truck bed to cool, thus resulting in uneven heat distribution throughout the mixture. Although some material transfer vehicles include mechanisms for re-mixing the asphalt material, segregation and temperature variation in the asphalt material that occurs during transport of the asphalt to the paving machine continue to be problems.
Conventional asphalt paving machines (and conventional hopper inserts) do not eliminate the problems of segregation and uneven heat distribution. Furthermore, they may even exacerbate the problem, because in the conventional hopper (and the conventional hopper insert), asphalt material at the front of the hopper or hopper insert is generally conveyed to the transverse distributing auger before asphalt material at the rear of the hopper or hopper insert. It would be desirable therefore if a hopper insert could be provided that would tend to remix the asphalt materials to obtain the desired size homogeneity and even temperature distribution.
USPTO Backgrounds
USPTO Backgrounds