Abstract:
A pothole repair machine utilizes hot mix asphalt material to fill the pothole being repaired. The machine includes a heating apparatus for raising the temperature of the surface of the road surrounding the pothole to soften the material for bonding with the material to be inserted into the pothole. A hot tack spray is then placed onto the surface of the pothole before hot mix material is deposited into the pothole cavity. Before depositing the hot mix material, a sensing mechanism determines the depth of the pothole and causes an adjustment of the height of screening doors to effect the uncompressed height of the filling material at a predetermined percentage of overfill before a vibrating roller compresses the filling material to the level of the surrounding roadway. A plurality of screening doors extends along the transverse width of the machine, each door being adjustably controlled by a depth sensor member.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is directed to machines for laying asphalt paving material and, more particularly, to a machine for repairing potholes in paved road surfaces. 
   Machines for repairing potholes are known in the art; however, most known pothole repair machines, such as is shown in U.S. Pat. No. 5,131,788, issued to Leslie Huliesko on Jul. 21, 1992; in U.S. Pat. No. 5,294,210, issued to Jerome Lemelson on Mar. 15, 1994; and in U.S. Pat. No. 5,752,782, issued to Leslie Huliesko on May 19, 1998, are designed to dispense a cold patch material in which the asphalt paving material is combined with an emulsion to provide a plastic paving material that will harden when placed into the environment. Such cold patch asphalt paving material is typically utilized in cold weather installations and suffers from the limitation of not being able to bond with the existing adjacent, contiguous paving material to enable the patch material to remain in place. Thus, pothole repairs accomplished in this manner are often temporary. 
   One approach often taken to attempt to prolong the life of a cold patch pothole repair is to spray a coating of tack material into the open pothole before dispensing the cold patch asphalt material into the pothole. The tack coat is conventional in the art of repairing potholes, as is disclosed in U.S. Pat. No. 4,557,626, issued to Jack McKay on Dec. 10, 1985, and in U.S. Pat. No. 4,215,949, issued to Gifford Gabriel on Aug. 5, 1980, in which the tack coat (or bonding agent) is sprayed into the pothole before the introduction of the cold patch material in an effort to make the cold patch material adhere to the bottom and sides of the pothole. 
   In U.S. Pat. No. 5,967,695, issued to Gulertan Vural on Oct. 19, 1999, and in U.S. Pat. No. 4,557,626, (McKay), the pothole repair machine is provided with a heating apparatus to heat the pothole and surrounding asphalt material primarily to remove excess material from the hole and from the surface of the roadway surrounding the pothole. Furthermore, in U.S. Pat. No. 5,967,695 (Vural) the process undertaken in the machine is to overfill the pothole and compact the filling material to a level higher than the surrounding roadway, whereupon the machine utilizes a vertically adjustable doctor blade to remove the excess filling material following which the filling material is again compacted. 
   U.S. Pat. No. 5,333,969, issued to James Blaha, et al on Aug. 2, 1994, discloses a self-propelled pothole repair machine in which the potholes can be repaired with hot mix asphalt filling material. The Blaha machine includes an insulated hood formed by an assembly of retractable doors to control the ambient temperature around the pothole during the repair process. The Blaha machine further includes a device for enlarging and making the shape and size of the pothole uniform before the filing material is added to the pothole for repair thereof. A portable cart for repairing potholes is disclosed in U.S. Pat. No. 6,439,806, issued to Harold Dillingham on Aug. 27, 2002, in which the process utilizes hot mix filling material to repair potholes. In U.S. Pat. No. 6,056,474, issued to David Nolan on May 2, 2000, a mechanism for controlling the height of a strike-off plate on an asphalt paver in response to the pitch angle of the screed is disclosed. 
   Such prior art pothole repair machines have not been configured to provide an efficiently operable and economically affordable system for the consistent repair of potholes. The Blaha machine, for example, is a large cumbersome apparatus in which the process is attempted to be automated. The Dillingham cart, on the other hand, is too small to be efficient in the repair of a large quantity of potholes. Cold patch pothole repair machines cannot provide a lasting repair, even with the utilization of a tack coat before the filling material is added to the pothole. Potholes are not formed in a regular uniform manner and uniformity cannot be relied upon in formulating a process to effect their repair. Accordingly, it would be desirable to provide a pothole repair machine that would be consistently and effectively operable to repair potholes, resulting in a repair that becomes consistent with the surrounding surface of the roadway. 
   SUMMARY OF THE INVENTION 
   It is an object of this invention to overcome the aforementioned disadvantages of the prior art by providing a pothole repair machine that will utilize a hot mix asphalt material to fill pothole for repair thereof. 
   It is another object of this invention to provide a pothole repair machine that provides a cost effective process for the repair of potholes in roadway surfaces. 
   It is a feature of this invention that the pothole repair machine incorporates a series of vertically adjustable doors to screen the filling material being deposited into a pothole for repair thereof. 
   It is an advantage of this invention that filling material is consistently overfilled by a predetermined percentage in order to compress to the level of the surrounding surface of the roadway. 
   It is another feature of this invention that the vertically adjustable doors are connected to a linkage mechanism that senses the depth of the pothole to be repaired so that the depth of filling material is overfilled by the predetermined percentage. 
   It is another advantage of this invention that the filling material can be compressed uniformly to the level of the surrounding surface of the adjacent roadway. 
   It is still another feature of this invention that the height of the vertically adjustable doors can be individually varied across the transverse width of the pothole repair machine. 
   It is still another advantage of this invention that the height of the entire machine above the surface of the roadway can be adjusted. 
   It is yet another feature of this invention that the pothole repair apparatus is enclosed within an insulated hood that controls the ambient temperature of the area around the pothole being repaired so that the temperature of the hot mix filling material will not cool until the pothole is repaired. 
   It is yet another advantage of this invention that the roadway surface around the pothole to be repaired is heated to facilitate the bonding of the filling material into the surface of the surrounding roadway. 
   It is a further feature of this invention that the machine can be trailed behind a conventional highway truck for transport over the surface of the highway for access to potholes to be repaired. 
   It is a further advantage of this invention that the vertically adjustable doors are automatically positioned in response to the sensed depth of the pothole being repaired. 
   It is yet another object of this invention to provide a pothole repair machine that is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
   These and other objects, features and advantages are accomplished according to the instant invention by providing a pothole repair machine utilizing hot mix asphalt material to fill the pothole being repaired. The machine includes a heating apparatus for raising the temperature of the surface of the road surrounding the pothole to soften the material for bonding with the material to be inserted into the pothole. A hot tack spray is then placed onto the surface of the pothole before hot mix material is deposited into the pothole cavity. Before depositing the hot mix material, a sensing mechanism determines the depth of the pothole and causes an adjustment of the height of screening doors to effect the uncompressed height of the filling material at a predetermined percentage of overfill before a vibrating roller compresses the filling material to the level of the surrounding roadway. A plurality of screening doors extends along the transverse width of the machine, each door being adjustably controlled by a depth sensor member. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a schematic side elevational view of a pothole repair machine incorporating the principles of the instant invention, the pothole repair machine being depicted in a transport configuration with the frame raised relative to the rear axle, the forward road heater being depicted in alternate transport positions with a raised transport position being shown in phantom, the maximum movement of the frame relative to the rear axle being depicted by the position of the rear axle in phantom; 
       FIG. 2  is a schematic rear elevational view of the pothole repair machine shown in  FIG. 1  with the rear compacting roller being removed to better depict the screening doors, but with the frame lowered to an operative position next to the surface of the road; 
       FIG. 3  is a schematic side elevational view of the pothole repair machine in an operative mode depicting the depth sensor members in operation, the transport position of the sensor members being shown in phantom and the spray of the hot tack coating also being depicted; and 
       FIG. 4  is a schematic rear elevational view of the pothole machine similar to that of  FIG. 2 , but showing the movement of the screening doors as actuated by the pivoted sensor members engaged with the bottom surface of a pothole, the brace for the doors being removed for purposes of clarity. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings, a pothole repair machine incorporating the principles of the instant invention can best be seen. The machine  10  is preferably a towed implement that can be attached to a pick-up truck (not shown) or a highway truck (not shown) by a trailer hitch  11  to be moved from one location to another. In the alternative, the machine  10  could be a self-propelled apparatus in which an engine is operatively mounted on the machine  10  to provide operative and motive power. The machine  10  includes a frame  12  supported above the ground by a pair of front wheels  13   a  and a pair of rear wheels  13   b . The frame  12  also supports a heated material hopper  25  for holding a supply of hot mix asphalt material. Manually operable controls  15  are associated with a hydraulic system (not shown) to control the operation of the various functions to be described and defined in greater detail below. The frame  12  also supports additional reservoirs  18 ,  19  for heated asphalt tack coat spray material and heated oil for a self-contained heating system described in greater detail below. 
   At the forward end of the machine  10 , a gas-fired road heater  20  is positioned adjacent the surface of the road R to heat the roadway surface sufficiently to soften the surface for bonding purposes, as will be described in greater detail below. Immediately rearwardly of the road heater  20 , a spray device  22  is positioned to spray a hot tack coat of asphalt coating material from the reservoir  18  onto the bottom surface of the pothole H. The heated material hopper  25  terminates in a sloped delivery chute  26  that directs the heated asphalt patch material toward a discharge opening  27 . A pivoted gate  29  covers the discharge opening  27  and is controlled through the manual controls  15  to expose the discharge opening  27  for the delivery of heated asphalt fill material into the pothole H. Preferably, the pivoted movement of the gate  29  is hydraulically controlled, but electric or mechanical controls would also be operable to control the discharge of asphalt fill material from the hopper  25 . 
   Once the asphalt fill material has been placed into the pothole H, a compacting roller  30 , preferably with an associated vibrating mechanism (not shown) to better compact the fill material, is supported at the rear of the frame  12  to compact the fill material to the level of the surrounding road surface R. As is conventional with compacting rollers, water can be added to the interior of the roller assembly to increase the weight of the roller  30 . Furthermore, water can be added to a reservoir  32  supported at the rear of the frame  12  in conjunction with the roller  30  to further increase the weight asserted against the fill material for compaction thereof. 
   Hot mix asphalt fill material is known to compress by approximately 10%–25% when compacted. Accordingly, an overfilling of the pothole H by 10%–25%, measured as a function of the depth of the pothole H, will result in a compacting of the fill material to the level of the surrounding road surface R. To accomplish this overfilling of the pothole H by 10% to 25% of the depth of pothole, the pothole repair machine  10  is provided with an automatic depth adjustment mechanism  40 . 
   The automatic depth adjustment mechanism  40  includes pivoted sensor members  42  that are pivotally supported on the frame  12  so that the distal end  43  of each respective sensor member  42  will drop into the pothole H and float against the bottom of the pothole H. A linkage  45  interconnects the forward end  44  of the sensor member  42  with a vertically movable door  50 , as is best seen in  FIG. 2 , that serves to screen the fill material placed into the pothole H. The linkage  45  is connected in a manner that raises the door  50  in response to dropping into the pothole H a greater distance. Accordingly, the deeper the pothole H, the higher the door  50  would be positioned, leaving a greater height of the fill material in the pothole H above the surface of the road R. Thus, the depth of the non-compacted fill material is in direct proportion to the depth of the pothole H. The function of the doors  50  is to screen off the fill material placed into the pothole H from the hopper  25 , and to shape the overfill of the fill material into a configuration that correlates to the corresponding depth of the pothole H. 
   The linkage  45  can include a rotatable mounted shaft  46 , corresponding to each respective set of pivoted sensor member  42  and corresponding screening door  50 , passing through the fill hopper  25  to exit rearwardly thereof to connect with the screening doors  50 . In such a mechanical arrangement, the pivotal movement of the sensor member  42  will cause a corresponding rotation of the shaft  46  through a connecting link  47 , which in turn effects an appropriate raising of the screening door  50  through a rearward connecting link  48 . A lost motion slot (not shown) in the rearward conning link  48  can be utilized to position the screening door  50  at the maximum height corresponding to the maximum depth identified by the corresponding sensor member  42  for each respective pothole H being repaired. A resetting of the doors  50  to the lowered position would reset the machine for the next pothole repair. Alternatively, a more accurate screening of the fill material can be accomplished through an electronic control system in which the sensed depth of the pothole H would be reflected in the varying height of the screening door  50  as the screening door  50  actually passes over the pothole being repaired. 
   As is best seen in  FIG. 2 , multiple doors  50  span the transverse width of the machine  10 . Each vertically adjustable door  50  is connected to a separate sensor member  42  so that each door  50  is positioned in direct correlation with the depth of the pothole H corresponding to the area covered by the door  50 . Accordingly, the amount of fill material overfilling the pothole H above the surface of the road R will vary from one door  50  to the other in response to the sensed depth of the pothole H. One skilled in the art will recognize that the greater the number of doors are provided, the finer the calibration of the height of the fill material will be; however, from a practical consideration, the number of doors  50  should be in the range of 6 to 10. A brace  51  is connected to the frame  12  and positioned immediately behind the screening doors  50  so that the engagement with the fill material will not deflect the doors  50  rearwardly. 
   Referring now to  FIGS. 1 and 2 , the machine  10  is provided with a depth adjuster  35 , preferably in the form of a pair of hydraulic cylinders  37  interconnecting the frame  12  and the rear axle  39  so that the frame  12  can be raised and/or lowered relative to the surface of the road R, thus providing a height adjustment for the entire machine  10 . Furthermore, by independently controlling the two hydraulic cylinders  37 , the machine  10  can be oriented angularly with respect to the level of the road surface R. As seen best in  FIG. 2 , a hydraulic motor  52  is operatively connected with the rear axle  39  to effect a driving of the machine  10  over the surface of the road R. Accordingly, once the pothole repair machine  10  is driven to a location at which potholes H are desired to be repaired, the machine  10  can be disconnected from the towing vehicle (not shown) and mobilely moved over the surface of the road R in either a forward or rearward direction by operating the hydraulic motor  52 . 
   To maintain an elevated temperature within the operative area for repairing the pothole, the operative area being defined at a minimum as the area in which the delivery chute drops the hot mix asphalt material into the pothole H, the area in which the screening doors  50  define the height of the overfill of material within the pothole H, and the area over which the fill material is being compacted, an insulated hood  55  is supported from the frame  12  around the operative area. Furthermore, a closed circuit, self-contained circulation system circulates heated oil from the reservoir  19  through the delivery chute  26  and through the compacting roller  30  to assist in maintaining the elevated temperatures within the operative area. To also assist in maintaining the elevated temperatures of the hot mix asphalt fill material, the circulation system can also circulate the heated oil around the insulated fill material hopper  25 . 
   Operating the road heater  20 , as well as heating the oil for circulation within the circulation system, requires a heating system (not shown) which will be understood by one of ordinary skill in the art as being supported on the frame  12  and will preferably utilized propane gas or the equivalent to provide the necessary energy for raising and maintaining the temperatures as described above. Furthermore, the various hydraulically controlled functions, such as the hydraulic cylinders  37 , the movable gate  29  on the delivery chute  26 , the operation of the hydraulic motor  52 , optional raising and lowering of the road heater  20 , direction the spraying of the tack coat, etc., requires a hydraulic system (not shown) on the machine  10 . Such a hydraulic system, as will be readily understood by one of ordinary skill in the art, can be self-contained on the machine  10  or be powered by a remote source, such as the hydraulic system on the prime move (not shown) moving the machine while in the transport mode. 
   In operation, the surface of the road R is heated by the road heater  20  until the road surface R is softened. An optional blower (not shown) can be utilized to clear debris or other loose material out of the pothole H, preferably before the road heater  20  is utilized. After the surrounding asphalt has been softened, a tack coat is sprayed into pothole H to cover the bottom surface of the pothole H to help the fill material to bond to the surfaces of the pothole. The sensor members  42  are released from a transport position described in greater detail below to pivot relative to the frame  12  to float against the bottom surface of the pothole H. Each sensor member  42  is connected to a corresponding door  50  through a linkage  45  that passes through the fill material hopper  25  to effect movement of the screening door  50  in response to the pivoted position of the sensor member  42  against the bottom of the pothole H. 
   After spraying the tack coat into the pothole H, the asphalt fill material is dropped from the hopper  25  through the delivery chute  26 , controlled through operation of the gate  29 , into the pothole H overfilling the pothole H. The rearwardly disposed screening doors  50  are positioned at a height to screen off the excess fill material so that the overfill of fill material is set at about 110% to 125% of the depth of the pothole H. The vibrating roller  30  compacts the fill material to the level of the surrounding road surface R. Since the surrounding road surface R has been softened through the operation of the road heater  20 , the compacting roller  30  bonds the fill material into the surrounding road surface R to provide an improved durability for the pothole repair. 
   The insulated hood  55  surrounds the machine  10  to maintain the heat generated by the road heater  20  and other components of the pothole repair machine  10  within the operative area of the machine  10 . Once the surrounding road surface R has been softened by the road heater  20 , the ambient temperature needs to be maintained to keep the surface in a softened state and to keep the fill material from cooling as it is being deposited into the pothole H and compacted by the roller  30 . Once the fill material has been compacted and bonded into the surrounding road surface R, the fill material is permitted to cool and harden into a permanent patch for the road surface. 
   After the potholes have been repaired and it is desired to move the pothole repair machine  10  to a new location, the hydraulic cylinders  52  are activated to raise the frame  12  relative to the road R and place the frame  12  into a transport configuration. The sensor members  42  are raised into a transport position, as best seen in  FIG. 1 , and locked by a lock pin (not shown) to fix the linkage  45  and the sensor members  42  in a raised, transport position. The screening doors  50  are then also fixed into a lowered transport position corresponding to the raised position of the sensor members  42 . Once transported to a new job site, the pothole repair machine  10  can be returned to an operative configuration simply by lowering the frame to the surface of the road R, the transport and operative positions of the frame  12  relative to the rear axle  39  being depicted in  FIG. 1  by the alternate locations of the rear axle  39 , and releasing the locked sensor members  42  to ride against the adjacent surface of the road or bottom of the pothole H. 
   Because of the insulated hood  55  trapping the heat within the operative area of the machine  10 , the pothole repair machine  10  can be utilized in the winter months as well as during the traditional warmer porthole repair months. The bonding of the fill material into the surrounding surface of the roadway, along with the utilization of a hot tack spray into the bottom of the pothole H, aids in the formation of a permanent pothole repair. The simplicity of the machine  10  permits the machine  10  to be cost effective in manufacture as well as in operation. 
   It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.