FIELD OF THE INVENTION 
     The present invention relates to conveyor systems and more particularly to a conveyor return idler assembly. 
     BACKGROUND OF THE INVENTION 
     Conveyor systems are used to move various types of goods in both commercial and manufacturing settings. Conveyors typically include a system comprising a pulley at one end and some type of driving mechanism at the opposite end. In general, a continuous looped belt, comprising an upper portion for moving goods and a parallel lower return portion, runs around the pulley and drive mechanisms. 
     The goods conveyed on such a system may shift or move slightly during transmission, or they may be placed on the belt in an unbalanced position. This unbalanced condition may result in belt wear or displacement. Idler systems have been developed to compensate for displaced or unbalanced belt loads. Here, a belt centralizing idler is positioned on the return portion of the belt. The idler consists of a roller apparatus which presses up against the belt and senses the belt and idler centers of gravity. If the centers of gravity are equal, the idler remains in a straight horizontal direction and in the direction of the belt. A difference between the two centers of gravity causes the idler to turn diagonally in the direction of the misaligned belt due to the presence of a belt weight present in the roller. This change in direction centers the belt on the conveyor system. The idler then returns to its original position on the belt. 
     The above-described centralizing idler is operational only while the conveyor belt travels in one direction (i.e., the forward direction). It is often desirable for a conveyor to transport goods in both the forward and reverse directions (i.e., bi-directional). Current bi-directional belt systems require manual operation in the reverse direction or the use of additional center drive assemblies and pulleys. These systems are expensive, cumbersome and require additional labor. What is needed in the art therefore is a bi-directional centralizing conveyor system which does not require manual operation or additional pulleys. 
     SUMMARY OF THE INVENTION 
     In one embodiment, the present invention relates to an apparatus for aligning a bidirectional conveyor belt, comprising two parallel idler rollers mounted between two brackets. The two rollers rotate in opposite directions. When mounted to the underside of a bidirectional conveyor belt, the apparatus shifts upward and downward along the axis of the shaft, allow each of the rollers to come into contact with the conveyor belt in an alternating manner. The idler rollers act to maintain alignment of the conveyor belt in either the forward or reverse directions, thus preventing erosion of the belt and the conveyor system. 
     In an additional embodiment, the invention is directed a system for maintaining the alignment of a conveyor belt. The system comprises a centralizing assembly with two parallel mounted idler rotatable rollers, where the idlers rollers rotate in opposite directions. The idler rollers rotate upward and downward, alternating contact with the belt. The system also utilizes an actuator to raise and lower the rollers so they contact the conveyor belt. 
     The invention also relates to a method of aligning a bidirectional continuous conveyor belt. A centralizing assembly with two parallel idler rotatable rollers is mounted to the underside of the forward portion of a conveyor belt. The idler rollers rotate in opposite directions and move upward and downward, alternating contact with the belt. The method further provides raising the first idler roller of the centralizing assembly until it comes into frictional contact with the bottom surface of the upper portion of the continuous conveyor belt. Forward motion of the conveyor belt is initiated causing rotation of the first idler roller and alignment of the conveyor belt in the forward direction. The first idler roller is lowered and thus disengaged allowing the second idler roller to come into contact with the bottom surface of the upper portion of the continuous conveyor belt. Movement of the belt in the reverse direction is then initiated, allowing the second idler roller of the centralizing assembly to rotate in a direction opposite the first idler roller and align the conveyor belt in the reverse direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure can be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the disclosure. Furthermore, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a side view of the conveyor return idler assembly of the invention; 
         FIG. 2  is a side view of the conveyor return idler assembly of the invention; 
         FIG. 3  is a top view of the conveyor return idler assembly of the invention; 
         FIG. 4  is a side view of the conveyor return idler assembly of the invention; 
         FIG. 5  is an additional top view of the conveyor return idler assembly of the invention; 
         FIG. 6  is a bottom view of the conveyor return idler assembly of the invention; 
         FIG. 7A  is a side view of a belt centralizing idler in an aligned position; 
         FIG. 7B  is a top view of a belt centralizing idler in an aligned position; 
         FIG. 8A  is a side view of a belt centralizing idler in a misaligned position; 
         FIG. 8B  is a top view of a belt centralizing idler in a misaligned position; 
         FIG. 9A  is a side view of an engaged conveyor return idler assembly of the invention in forward direction; 
         FIG. 9B  is a side view of a disengaged conveyor return idler assembly of the invention in the reverse direction. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1-6 , an embodiment of the present invention herein referred to as a conveyor return idler assembly  10  includes two roller shaped idlers  28  and  30 . Such idlers  28  and  30  are known to one of skilled in the art. Exemplary idlers include those manufactured by Brelko Conveyor Products (Johannesburg, South Africa) and Sandvik AB (Stockholm, Sweden). One of skill in the art will understand that the presently disclosed invention is not limited to these specific idlers. Referring now to  FIGS. 7A and 7B , exemplary idler  28  is illustrated with a center of gravity  50 . As will be described in more detail below with specific reference to  FIGS. 8A and 8B , each idler  28  and  30  moves from side to side horizontally along axis  50  (as indicated by arrows  52  and  54 , respectively) in order to align with the direction of movement of conveyor belt  26 . Such movement or tilting occurs in response to a change in the center of gravity of the idler  28  as compared to the center of gravity of the belt  26 . Referring now to  FIG. 1 , idlers  28  and  30  additionally rotate in opposite directions, matching the movement of the conveyor belt  26  in either the forward or backward direction. Here, idler  28  rotates in a clockwise direction while idler  30  rotates in a counter-clockwise direction. 
     As illustrated in  FIG. 3 , idlers  28  and  30  are rotatably mounted at each end to the respective ends of two triangular-shaped idler brackets  20  and  21 . Idler  28  is parallel to idler  30 , while bracket  21  is parallel to bracket  21 , conferring a generally square confirmation to apparatus  10 . The brackets  20  and  21  and idlers  28  and  30  may be constructed from any durable material as is known in the art, for example a metal. As shown in the figures, the assembly  10  further includes a cylindrical shaft  22 . Shaft  22  is rotatably mounted at its respective ends to the first idler bracket  20  and the second parallel idler bracket  21  ( FIG. 3 ) near the upper-most portion or approximate apex of the brackets. The shaft  22  is so positioned to be parallel to idlers  28  and  30  and perpendicular to brackets  20  and  21 . Shaft  22  is mounted at the approximate midpoint of the inside surfaces of the idler brackets  20  and  21  and secures a pair movable mount plates  24  and  25  located adjacent to the inside surfaces of brackets  20  and  21 . Movable mount plates are located parallel to brackets  20  and  21 . As illustrated in  FIG. 1 , assembly  10  is located on the underside or return portion of a continuous conveyor belt  26 . Belt  26  is in the form of a loop (not shown) with an upper conveying portion and a lower return portion. Any type of continuous conveyor belt, as is known to one of skill in the art, may be used with the present invention. 
     Turning now to  FIG. 3 , idlers  28  and  30  are shaped as long tubes or rollers and are rotatably attached at their respective ends to idler brackets  20  and  21 . The idlers  28  and  30  are rotatably supported between idler brackets  20  and  21 . An L-shaped shaft bracket  32  abuts against each end of the rollers  28  and  30  and secures the rollers  28  and  30  to the idler brackets  20  and  21  with two vertically aligned shaft bracket gussets  34  (see also  FIG. 4 ). The two mount plates  24  and are attached to the rotating shaft  22  at the terminal ends. Referring now to  FIG. 1 , belt  26  slides on the smooth surface defined by the mount plates  24  and  25 . The shaft  22  is attached to the bottom side of the mount plate  24  via mounting bracket  40  and mounting screws  42 . The mounting bracket  40  and mounting screws  42  secure the mount plate  24  but allow the plate  24  to rotate ( FIG. 4 ). As will be described in more detail below, the plate  24  swivels or tilts up and down along the rotational axis provided by the shaft  22 . 
     Referring again to  FIG. 1 , the assembly  10  further includes a hydraulic actuator  46  which is secured to the idler bracket  20  at by actuator bracket  48 . In one embodiment, the actuator  46  consists of a cylinder barrel  47 , into which a piston  49  connected to a piston rod (not shown) moves in and out. The barrel  47  is closed on one end by the cylinder bottom (not shown) and the other end by the cylinder head (not shown) where the piston rod exits the barrel  47 . 
     In operation, the assembly  10  of the present disclosure is mounted to the underside of the upper portion  62  (i.e., forward) of a continuous belt system  60 , as illustrated in  FIGS. 9A and 9B . The conveyor belt illustrated in  FIGS. 9A and 9B  is for illustration only as the present assembly  10  may be utilized in a variety of systems. Here, the belt system  60  includes a conveyor frame  70  comprising a number of vertical and horizontal supports  71 . The particular frame construction of the system  60  may vary. The frame  70  may rest on the ground or be supported off the ground by support members (not shown), as is appropriate for a particular application. 
     As illustrated in  FIGS. 7A and 7B , a properly aligned belt slides along the smooth surface of plates  24  and  25 . The center of gravity of idler  28  is aligned with that of the belt  26 . Here, the idler is aligned horizontally and rotates in the same direction of the movement of belt  26 . Belt  26  continues moving in a straight, forward direction and does not deviate from the surface of plates  24  and  25 . This configuration prevents untimely wear or other damage to the belt  26  or other parts of the conveyor assembly. 
     Turning again to  FIG. 9A , the continuous belt  26  includes an upper or forward portion  62  and a lower or return portion  64 . Goods (not shown) are first loaded onto the top surface of the forward portion  62  for transport in the forward direction, as indicated by arrow  66 . The conveyor operator (not shown) then initiates a signal to the belt system  60  to begin movement in the forward direction  66 . After receiving the signal initiating movement in the forward direction, the hydraulically activated actuator  46  retracts the piston  49  into barrel  47 , causing the shaft  22  to rotate in a counter clockwise direction. This rotation of shaft  22  initiates movement or tilting of the ends of idler brackets  20  and  21  and idler  28  in the upward direction, accompanied by a concurrent movement or tilting of the opposite ends of the idler brackets  20  and  21  (i.e., the ends comprising idler  30 ) in the downward direction. As a result, idler  28  frictionally engages with the underside of belt  26  and begins to rotate in a clockwise or forward direction. 
     In the event that the goods on the belt  26  become unbalanced and/or the belt  26  becomes misaligned and moves off the surface of plates  24  and  25 , idler  28  moves or tilts along axis  50  (movement indicated by arrows  52  and  54 , respectively) in order to maintain frictional contact with the conveyor belt  26  and to correct any resulting misalignment of the belt  26  ( FIGS. 8A and 8B ). Such movement or tilting occurs in response to a change in the center of gravity of the idler  28  as compared to the center of gravity of the belt  26 . If the centers of gravity are mismatched, idler  28  rotates slightly at axis  50  until the idler  28  and the belt  26  are horizontally aligned. The tilting of the idler  28  is accompanied by a tilting of the plates  24  and  25  in the same direction of the movement of belt  26  and realignment of the belt  26 . The idler  28  returns to its original orientation (i.e., perpendicular to idler brackets  20  and  21 ) when the centers of gravity of the idler  28  and the belt  26  are parallel. In this configuration, the idler  28  is aligned horizontally and rotating in the same direction as belt  26 , as illustrated in  FIGS. 7A and 7B . 
       FIG. 9B  is an illustration of the operation of the assembly  10  when the belt  26  is operating in the return or reverse direction, as indicated by arrow  68 . It is to be understood that the apparatus  60  illustrated in  FIG. 9B  includes corresponding structures as shown in  FIG. 9A . Here, the forward motion of the belt  26  is stopped by the operator. Once the hydraulically activated actuator  46  receives the signal that forward movement of the belt  26  has stopped, the piston  49  expands from barrel  47 , causing the shaft  22  to rotate in a clockwise direction. This rotation of shaft  22  initiates movement or tilting of the end of idler brackets  20  and  21  and idler  28  in the downward direction and a concurrent movement or tilting of the opposite end of the idler brackets  20  and  21  (i.e., the ends containing idler  30 ) in an upward direction. As a result, idler  28  disengages from the underside of belt  26 . 
     Referring again to  FIG. 9B , the operator then initiates a signal for the belt to move in the reverse direction. Upon receipt of this signal, the piston  49  further expands from barrel  47 , continuing to tilt the ends of idler brackets  20  and  21  and idler  28  in the downward direction and a concurrent movement or tilting of the opposite end of the idler brackets  20  and  21  (i.e., the ends containing idler  30 ) in an upward direction. Idler  30  then frictionally engages the underside of belt  26 . Reverse movement of the belt  26  in the direction of arrow  68  causes rotation of idler  30  in a counter-clockwise direction. Similar to the action of idler  28  (as illustrated in  FIGS. 8A and 8B ), idler  30  moves or tilts along the axis  50  as (indicated by arrows  52  and  54 , respectively) in order to maintain frictional contact with the conveyor belt  26 . Such movement or tilting occurs in response to a change in the center of gravity of the idler  30  as compared to the center of gravity of the belt  26 . If the centers of gravity are mismatched or the belt slides from the surface of plates  24  and  25 , idler  30  rotates slightly at axis  50  until the idler  30  and the belt  26  are horizontally aligned and the belt  26  is centered on plates  24  and  25 . The idler  30  then returns to its original orientation (i.e., perpendicular to idler brackets  20  and  21 ) when the centers of gravity of the idler  28  and the belt  26  are parallel. In this configuration, the idler  30  is aligned horizontally and rotating in the same direction as belt  26 , as illustrated in  FIGS. 7A and 7B . 
     The assembly  10  described herein allows for the continual alignment of a conveyor belt in both the forward and reverse directions while utilizing unidirectional idlers. In one exemplary embodiment, multiple assemblies  10  may be placed along the belt  26  length to ensure proper alignment along the conveyor system, as is known to one of skill in the art. 
     The present disclosure contemplates changes in the above constructions without departing from the scope of the invention. All matter contained in the above description are shown in the accompanying drawings should be interpreted as illustrative and not limiting.
The present invention relates to an apparatus for aligning a bidirectional conveyor belt. The apparatus comprises two parallel idler rollers mounted in a parallel configuration between two brackets. The two rollers rotate in opposite directions and are mounted to the underside of a bidirectional conveyor belt. During operation, the apparatus shifts upward and downward along the axis of a shaft, allowing each of the rollers to come into contact with the conveyor belt in an alternating manner. The idler rollers act to maintain alignment of the conveyor belt in either the forward or reverse directions, thus preventing erosion of the belt and the conveyor system. The invention is further directed a system for maintaining the alignment of a conveyor belt using the idler assembly, ad a method of aligning a bidirectional continuous conveyor belt.