Road structure – process – or apparatus – Apparatus – Automatic control
Reexamination Certificate
1999-07-20
2001-01-09
Pezzuto, Robert E. (Department: 3671)
Road structure, process, or apparatus
Apparatus
Automatic control
C404S072000, C404S075000
Reexamination Certificate
active
06171017
ABSTRACT:
BACKGROUND
The present invention relates to roadway maintenance and crack repair, and more particularly to systems for cleaning and filling such cracks that typically develop over time in roadways having coatings of concrete or asphalt including bitumen and aggregate and the like.
In roadway maintenance, crack repair traditionally involves manually cleaning the cracks by removing material therefrom, and filling with a material that may contain aggregate. In some cases, a stream of the thermoplastic material is manually directed onto the roadway generally into the crack, with some of the thermoplastic material (such as tar) remaining on the roadway surface on opposite sides of the crack. In other cases, a crack sealant is used to fill cracks that are first enlarged by sawing or routing during the cleaning. U.S. Pat. No. 5,215,071 to Mertes et al. discloses a riding pavement saw having a hydraulically powered blade that rotates on a generally horizontal axis, the blade being supported approximately midway between a pair of front wheels, the machine being steered by a single rear wheel that is operator-controlled.
U.S. Pat. No. 4,407,605 to Wirtgen discloses a powered vehicle having a pavement heater and milling device, modified to provide a rotating chisel cutter for removing a relatively wide portion of the pavement to an adjustable depth in the repair of longitudinal cracks. The milling device is mounted for laterally adjustable positioning relative to the vehicle, whereby initial positioning of the vehicle can be simply parallel to the crack, the vehicle being further maneuvered to follow the crack after the lateral positioning of the milling device is completed. The cutter rotates on a transverse horizontal axis, with chisel elements being spaced along the axis and located within a container that is fed with aggregates and/or liquid to be mixed with pavement that is removed by the milling device, the augmented aggregate mix being reapplied from the container onto the roadway.
U.S. Pat. No. 4,954,010 to Montgomery et al. discloses a maintenance truck equipped with a transverse-mounted slurry sealant box assembly for filling transverse roadway cracks and blending stepped pavement segments
These and other devices for roadway crack cleaning and repair have a number of disadvantages including, for example, one or more of the following:
1. They are excessively large and consequently difficult to maneuver, in many cases also requiring excessive lane width to be closed to regular traffic;
2. They are difficult to use in that the operator is required to manually steer the vehicle to accurately follow the crack, being particularly difficult when the driver's position does not afford a clear view of the crack and/or when lighting conditions are poor;
3. They have limited capability for following random cracks in that the cutters rotate on horizontal or generally horizontal axes;
4. They have limited effectiveness in that optional secondary operations that are indicated for portions of certain cracks (based on visual inspection, for example) are not permitted prior to filling; and
5. They are expensive to provide and operate in that they require heating and/or removal of excessive amounts of roadway material.
Thus there is a need for a roadway crack cleaning and repair system that overcomes the disadvantages of the prior art.
SUMMARY
The present invention meets this need by providing a roadway repair system including an appliance platform that is transversely driven relative to a vehicle in response to sensors thereby to automatically follow the crack as the vehicle is driven generally over the crack. In one aspect of the invention, the repair system includes a steerable vehicle for navigating the roadway; a platform assembly supported relative to the vehicle, at least a portion of the platform assembly being spaced directly above the roadway and being laterally movable relative to the vehicle; a sensor unit mounted on the movable portion of the platform and directed to the roadway below the platform assembly for detecting local variations in a sensed parameter during movement of the vehicle, a sensed continuous local deviation of the parameter being indicative of a roadway crack; a controller responsive to the sensor unit for generating an actuator drive signal that reflects a sensed lateral position of the crack relative to the sensor; an actuator for laterally positioning the platform in response to the actuator drive signal; and an appliance supported on the movable portion of the platform for performing a maintenance operation on the crack as the appliance follows the crack. As used herein, the terms laterally and longitudinally are orthogonal orientations relative to the vehicle being generally correspondingly aligned with the crack. In the case of cracks running generally longitudinally in the roadway, lateral and longitudinal have direct correspondence with a vehicle frame of reference. However, it is also contemplated than when cracks run generally across the roadway, laterally means forwardly and rearwardly with respect to the vehicle, there being a cross-slide carriage on the vehicle for supporting the platform. In that case, the vehicle is maneuvered generally perpendicular to the crack with the sensor unit positioned over the crack, and the cross-slide carriage is operated for traversing the crack, the appliance following the crack as indicated above.
The sensed parameter can be a spacing of the roadway below the platform assembly, a sensed continuously locally increased spacing being indicative of the crack. The sensor unit can include an array of sensor elements, each sensor element being directed to a respective portion of the roadway and producing a corresponding sensor signal. Preferably each sensor includes a source of radiation for projecting onto the roadway, the sensor signals being responsive to reflected portions of the radiation whereby the sensor unit is effective in the absence of ambient lighting. Preferably the sensor unit includes at least three of the sensor elements for enhanced crack detection, the elements being in a single laterally extending row. In cases wherein the width of the sensor elements is greater than a desired resolution of the sensor unit, the sensor unit preferably has the sensor elements in two rows, there being at least five of the sensor elements with an even number of the elements being in a first laterally extending row, an odd number of the elements being in a second laterally extending row that is longitudinally adjacent the first row, the odd number being one different from the even number, the sensors of the different rows being laterally interleaved for avoiding detection gaps between adjacent sensors. As used herein, the term longitudinally means orthogonally to the direction of lateral movement of the platform assembly, being generally in the direction of the crack. The first row can have four of the sensors, the second row having three of the sensors. Preferably the second row of sensor elements is displaced rearwardly of the first row for locating a central one of the sensors more closely to a following appliance. As used herein, rearwardly means perpendicular to the lateral movement of the platform assembly and opposite to the direction of movement of the sensor unit in tracking the crack.
The movable portion of the platform assembly can be supported by at least one glide shaft being connected to the vehicle, the actuator including a gear rack supported in parallel relation to the glide shaft, and a control motor supported on the platform assembly and having a pinion engaging the gear rack.
The appliance can be a router unit including a spindle assembly having a spindle shaft rotatably mounted in a spindle stator; a resilient mount for yieldingly supporting the spindle stator vertically oriented and laterally aligned with the sensor unit rearwardly thereof; means for rigidly mounting a routing cutter to the spindle shaft with the cutter extending below a nominal roadway height; and means for powering the spindle, wher
Pezzuto Robert E.
Sheldon & Mak
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