Patent Publication Number: US-2022228328-A1

Title: Self-balancing uni-drum compactor

Description:
FIELD 
     The inventive concepts relate to surface compactors machines, and, in particular, to uni-drum surface compactor machines. 
     BACKGROUND 
     Surface compactor machines, or surface compactors, are used to compact a variety of substrates, such as asphalt and soil. Surface compactors are provided with one or more compacting surfaces for this purpose. For example, a roller compactor may be provided with one or more cylindrical drums that provide compacting surfaces for compacting soil, asphalt, or other materials. 
     Roller compactors use the weight of the compactor to compress the surface being rolled. In addition, one or more of the drums of some roller compactors may vibrate to induce additional mechanical compaction of the surface being rolled. 
     Heavy duty surface compactors typically have two rollers or drums, e.g., front and back rollers, that provide compaction of the surface. An operator cab may be positioned between the rollers. The drums in such a compactor, referred to as tandem drums, may vibrate or be static, and may be driven by a motor mounted next to or under the operator cab. 
     A single-drum (or uni-drum) compactor only includes a single compacting drum. A conventional single drum compactor may include drive tires that propel the compactor and an operator cab positioned between the drum and the drive tires. For light duty, walk behind single drum compactors are also known. Such compactors may be driven by motors provided within the drum. 
     SUMMARY 
     This summary is provided to introduce simplified concepts that are further described below in the Detailed Description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter. 
     A surface compactor machine according to some embodiments includes a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, and an eccentric assembly mechanically coupled to the cylindrical drum and arranged to impart vibration to the cylindrical drum when the eccentric assembly is rotated. The cylindrical drum and the eccentric assembly form part of an unsprung mass having a combined first center of gravity. A head plate is affixed to the cylindrical spool through a shock isolator, and a sprung mass is rotationally coupled to the head plate along an axis of rotation of the cylindrical drum shell and the cylindrical spool. The sprung mass includes a plurality of components having a combined second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. The sprung mass includes a traction system including a traction motor and a slewing gear coupled to the traction motor. The traction system rotates the sprung mass relative to the head plate about the axis of rotation. 
     A surface compactor machine according to further embodiments includes an unsprung mass having a first center of gravity, the unsprung mass including a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, and a sprung mass rotationally coupled to the cylindrical spool along an axis of rotation of the cylindrical drum shell and the cylindrical spool. The sprung mass has a second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. The sprung mass includes a traction system including a traction motor and a slewing gear coupled to the traction motor. The traction system is configured to rotate the sprung mass relative to the cylindrical spool about the axis of rotation. When the surface compactor machine is in the stationary position, the first center of gravity of the unsprung mass and the second center of gravity of the sprung mass are in vertical alignment, and when the traction system rotates the sprung mass relative to the cylindrical spool about the axis of rotation, the second center of gravity of the sprung mass is rotated out of vertical alignment with the first center of gravity of the unsprung mass, thereby imparting torque to the cylindrical spool that causes rotation of the cylindrical drum. 
     A surface compactor machine according to further embodiments incudes a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, the cylindrical drum shell and the cylindrical spool having an axis of rotation, and an eccentric shaft mechanically coupled to the cylindrical drum and arranged to impart vibration to the cylindrical drum when the eccentric shaft is rotated. The cylindrical drum and the eccentric shaft form part of an unsprung mass having a combined first center of gravity. The machine further includes a head plate affixed to the cylindrical spool through a shock isolator, and a vibration motor coupled to the vibration shaft. The vibration motor is positioned outside the cylindrical spool and is coupled to the vibration shaft through a constant velocity joint. 
     The machine further includes a sprung mass rotationally coupled to the head plate along the axis of rotation and having a second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. 
     Aspects of the Inventive Concepts 
     In one aspect, a surface compactor machine includes a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, and an eccentric assembly mechanically coupled to the cylindrical drum and arranged to impart vibration to the cylindrical drum when the eccentric assembly is rotated. The cylindrical drum and the eccentric assembly form part of an unsprung mass having a combined first center of gravity. A head plate is affixed to the cylindrical spool through a shock isolator, and a sprung mass is rotationally coupled to the head plate along an axis of rotation of the cylindrical drum shell and the cylindrical spool. The sprung mass includes a plurality of components having a combined second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. The sprung mass includes a traction system including a traction motor and a slewing gear coupled to the traction motor. The traction system rotates the sprung mass relative to the head plate about the axis of rotation. 
     In an aspect, when the surface compactor machine is in the stationary position, the first center of gravity of the unsprung mass and the second center of gravity of the sprung mass are in vertical alignment. 
     In an aspect, when the traction system rotates the sprung mass relative to the head plate about the axis of rotation, the second center of gravity of the sprung mass is rotated out of vertical alignment with the first center of gravity of the unsprung mass, thereby imparting torque to the cylindrical drum that causes rotation of the cylindrical drum. 
     In an aspect, the rotation imparted to the cylindrical drum imparts linear motion of the cylindrical drum in a direction from the first center of gravity of the unsprung mass toward the second center of gravity of the sprung mass. 
     In an aspect, the shock isolator provides vibrational isolation of the sprung mass from vibration of the cylindrical drum generated by the eccentric assembly. 
     In an aspect, the eccentric assembly includes an eccentric shaft disposed with in the cylindrical drum and rotationally driven by a vibration motor. 
     In an aspect, the slewing gear is coupled to the head plate. 
     In an aspect, the traction motor is coupled to the slewing gear through a planetary gear. 
     In an aspect, the traction system includes a drive shaft coupled to the traction motor and the slewing gear and a safety brake coupled to the drive shaft. 
     In an aspect, the vibration motor is positioned outside the head plate relative to the cylindrical spool and is coupled to the eccentric shaft through a constant velocity joint. 
     In an aspect, the surface compactor machine further includes a frame forming part of the sprung mass, wherein the traction system is mounted to the frame. 
     In an aspect, the frame extends partially within a space defined by the cylindrical drum shell adjacent the cylindrical spool, and wherein the drive motor is disposed at least partially within the space defined by the cylindrical drum shell adjacent the cylindrical spool. 
     In an aspect, the sprung mass further includes an engine mounted on the frame, a counterweight mounted on the frame, and/or a bumper mounted on the frame. 
     In an aspect, the surface compactor machine further includes a second head plate affixed to the second cylindrical spool through a second shock isolator, and a second traction system including a second traction motor and a second slewing gear coupled to the second traction motor, wherein the second traction system is configured to rotate the sprung mass relative to the second head plate about the axis of rotation. 
     In another aspect, a surface compactor machine includes an unsprung mass having a first center of gravity, the unsprung mass including a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, and a sprung mass rotationally coupled to the cylindrical spool along an axis of rotation of the cylindrical drum shell and the cylindrical spool. The sprung mass has a second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. The sprung mass includes a traction system including a traction motor and a slewing gear coupled to the traction motor. The traction system is configured to rotate the sprung mass relative to the cylindrical spool about the axis of rotation. When the surface compactor machine is in the stationary position, the first center of gravity of the unsprung mass and the second center of gravity of the sprung mass are in vertical alignment, and when the traction system rotates the sprung mass relative to the cylindrical spool about the axis of rotation, the second center of gravity of the sprung mass is rotated out of vertical alignment with the first center of gravity of the unsprung mass, thereby imparting torque to the cylindrical spool that causes rotation of the cylindrical drum. 
     In an aspect, the unsprung mass further includes an eccentric assembly mechanically coupled to the cylindrical drum and arranged to impart vibration to the cylindrical drum when the eccentric assembly is rotated. 
     In an aspect, the surface compactor machine further includes a head plate affixed to the cylindrical spool through a shock isolator and coupled to the slewing gear of the traction system, wherein the traction system is configured to rotate the sprung mass relative to the head plate about the axis of rotation. 
     In an aspect, the slewing gear includes a slewing gear coupled to the head plate. 
     In an aspect, the eccentric assembly includes an eccentric shaft, the surface compactor machine further includes a vibration motor coupled to the eccentric shaft, wherein the vibration motor is positioned outside the head plate relative to the cylindrical spool and is coupled to the eccentric shaft through a constant velocity joint. 
     In an aspect, the surface compactor machine further includes a frame forming part of the sprung mass, wherein the traction system is mounted to the frame, wherein the frame extends partially within a space defined by the cylindrical drum shell adjacent the cylindrical spool, and wherein the drive motor is disposed at least partially within the space defined by the cylindrical drum shell adjacent the cylindrical spool. 
     In another aspect, a surface compactor machine incudes a cylindrical drum including a cylindrical drum shell and a cylindrical spool disposed within the cylindrical drum shell and supporting the cylindrical drum shell, the cylindrical drum shell and the cylindrical spool having an axis of rotation, and an eccentric shaft mechanically coupled to the cylindrical drum and arranged to impart vibration to the cylindrical drum when the eccentric shaft is rotated. The cylindrical drum and the eccentric shaft form part of an unsprung mass having a combined first center of gravity. The machine further includes a head plate affixed to the cylindrical spool through a shock isolator, and a vibration motor coupled to the vibration shaft. The vibration motor is positioned outside the cylindrical spool and is coupled to the vibration shaft through a constant velocity joint. The surface compactor machine further includes a sprung mass rotationally coupled to the head plate along the axis of rotation and having a second center of gravity that is lower than the first center of gravity when the surface compactor machine is in a stationary position. 
     In an aspect, the sprung mass includes a traction system including a traction motor and a slewing gear coupled to the traction motor, wherein the traction system is configured to rotate the sprung mass relative to the unsprung mass about the axis of rotation. 
     In an aspect, when the surface compactor machine is in the stationary position, the first center of gravity of the unsprung mass and the second center of gravity of the sprung mass are in vertical alignment. 
     In an aspect, when the traction system rotates the sprung mass relative to the head plate about the axis of rotation, the second center of gravity of the sprung mass is rotated out of vertical alignment with the first center of gravity of the unsprung mass, thereby imparting torque to the cylindrical drum that causes rotation of the cylindrical drum. 
     In an aspect, the rotation imparted to the cylindrical drum imparts linear motion of the cylindrical drum in a direction from the first center of gravity of the unsprung mass toward the second center of gravity of the sprung mass. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a single drum surface compactor machine according to some embodiments. 
         FIG. 2  is a cutaway perspective view of a single drum surface compactor machine according to some embodiments. 
         FIG. 3  is a side cutaway view of a single drum surface compactor machine according to some embodiments. 
         FIG. 4  is a plan cutaway view of a single drum surface compactor machine according to some embodiments. 
         FIG. 5  is a side elevation of a single drum surface compactor machine according to some embodiments. 
         FIG. 6  is a schematic side elevation of a single drum surface compactor machine according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a perspective view of a single drum surface compactor machine  10  according to some embodiments. As will be appreciated, a single drum surface compactor machine may be a self-propelled autonomous or semi-autonomous vehicle for compacting a substrate. 
     Referring to  FIG. 1 , the surface compactor machine  10  has a split drum construction. In particular, the surface compactor machine  10  includes a split cylindrical drum  12  including first and second cylindrical drums  12   a ,  12   b  arranged along a common axis of rotation. Each of the cylindrical drums  12   a ,  12   b  includes an independent drive system and can rotate independently to allow the surface compactor machine  10  to move forward/backward, steer left of right, and/or to change directions. Each of the cylindrical drums  12   a ,  12   b  includes a cylindrical drum shell  14   a ,  14   b  that contacts an underlying substrate. Compaction of the substrate is achieved as a result of the weight of the surface compactor machine  10  as it rolls over the substrate. Compaction of the substrate may be enhanced by vibration of the cylindrical drums  12   a ,  12   b , as described in more detail below. 
       FIG. 2  is a cutaway perspective view,  FIG. 3  is a side cutaway view, and  FIG. 4  is a plan cutaway view of the surface compactor machine  10  showing various internal components of the surface compactor machine  10 .  FIG. 5  is a side elevation of the surface compactor machine  10 . 
     Referring to  FIGS. 1 to 5 , each of the cylindrical drums  12   a ,  12   b  of the surface compactor machine  10  includes a cylindrical spool  16   a ,  16   b  disposed within the cylindrical drum shell  14   a ,  14   b . As best seen in  FIG. 3 , the cylindrical drums  12   a ,  12   b  and the cylindrical spools  16   a ,  16   b  rotate around a common axis of rotation  20 . The cylindrical spools  16   a ,  16   b  are coupled together by means of a slewing bearing  35  ( FIG. 3 ), which allows independent rotation of the cylindrical drums  12   a ,  12   b  about the axis of rotation  20 . 
     The surface compactor machine  10  includes an eccentric assembly  18  that is mechanically coupled to the cylindrical drums  12   a ,  12   b  and arranged to impart vibration to the cylindrical drum when the eccentric assembly  18  is rotated. The cylindrical drums  12   a ,  12   b  and the eccentric assembly  18  form part of an unsprung mass  22  having a combined first center of gravity G 1  approximately near the axis of rotation  20  ( FIG. 5 ). As will be described in more detail below, other components of the surface compactor machine  10  form a sprung mass  32  that is at least partially isolated from vibration of the unsprung mass  22  by means of shock isolators, although some vibration of the unsprung mass  22  may be transmitted through the shock isolators to the sprung mass  32 . 
     Referring to  FIG. 3 , a head plate  24   a ,  24   b  is affixed to each cylindrical spool  16   a ,  16   b  through a respective set of shock isolators  26   a ,  26   b . The shock isolators  26   a ,  26   b  provide vibrational isolation of the sprung mass  32  from vibration of the cylindrical drums  12   a ,  12   b  generated by rotation of the eccentric assembly  18 . A frame  60   a ,  60   b  is mounted to the head plate  24   a ,  24   b  through a slewing gear  38   a ,  38   b . A portion of the frame  60   a ,  60   b  may extend partially into a space defined by the cylindrical drum shell  14   a ,  14   b  adjacent the spool  16   a ,  16   b . Elements of the sprung mass  32  may be mounted to the frame  60   a ,  60   b.    
     The eccentric assembly includes an eccentric shaft  42  disposed within the cylindrical drums  12   a ,  12   b  and rotationally driven by a vibration motor  44  that is mounted outside the spools  16   a ,  16   b  in the illustrated embodiment. The vibration motor  44 , which is mounted to the frame  60   a , forms part of the sprung mass  32  and is at least partially isolated from vibration of the eccentric assembly  18 . The vibration motor  44  is coupled to the eccentric shaft  42  through a constant velocity joint  58 . The vibration motor  44  rotates the eccentric assembly to impart vibration to the drums  12   a ,  12   b  to enhance compaction of the substrate. The continuous velocity joint  58  is able to transfer high speed and bear with deflections of the shock isolators  26   a ,  26   b . This construction enhances isolation of the electrical and electronical components from vibrations, since all electrical components are mounted on the cushioned frame  60   a ,  60   b.    
     The sprung mass  32  includes a plurality of components having a combined second center of gravity G 2  ( FIG. 5 ) that is lower than the first center of gravity G 1  when the surface compactor machine  10  is in a stationary position (i.e., the drums  12   a ,  12   b  are not rotating). 
     Referring to  FIG. 4 , the sprung mass  32  includes traction systems  34   a ,  34   b  for each of the drums  12   a ,  12   b . The traction systems  34   a ,  34   b  each include a traction motor  36   a ,  36   b  and a slewing gear  38   a ,  38   b  coupled to the traction motor  36   a ,  36   b . The traction motor  36   a ,  36   b  and slewing gear  38   a ,  38   b  are mounted to the frame  60   a ,  60   b . The traction system includes a drive shaft  48   a ,  48   b  coupled to the traction motor  36   a ,  36   b  and the slewing gear  38   a ,  38   b , and a safety brake  52   a ,  52   b  coupled to the drive shaft  48   a ,  48   b . The traction motor  36   a ,  36   b  is coupled to the slewing gear  38   a ,  38   b  through a 90-degree planetary reduction gear  46   a ,  46   b . The slewing gear  38   a ,  38   b  contacts a slewing bearing  40   a ,  40   b  that is coupled to the head plate  24   a ,  24   b . As is known in the art, a slewing bearing permits independent rotation of the joined bodies. In this case, the slewing bearing  40   a ,  40   b , which is centered on the axis of rotation  20 , enables independent rotation of the sprung mass  32  connected to the frame  60   a ,  60   b  and the unsprung mass  22  connected to the head plate  24   a ,  24   b . When the traction motor  36   a ,  36   b  turns the slewing gear  38   a ,  38   b  via the drive shaft  48   a ,  48   b , the sprung mass  32  rotates about the axis of rotation  20  independently of the unsprung mass  22 . That is, when the slewing gear  38   a ,  38   b  is driven by the traction motor  36   a ,  36   b  against the slewing bearing  40   a ,  40   b , the sprung mass  32  rotates about the axis of rotation  20  relative to the unsprung mass  22 . 
     Accordingly, in each drum  12   a ,  12   b , the traction system  34   a ,  34   b  rotates the sprung mass  32  about the axis of rotation  20  relative to the head plate  24   a ,  24   b  and the unsprung mass  22 . The sprung mass  32  is rotationally coupled to the head plate  24   a ,  24   b  along the axis of rotation  20  of the cylindrical drum shells  14   a ,  14   b  and the cylindrical spools  16   a ,  16   b  via the slewing bearings  40   a ,  40   b.    
     As shown in  FIG. 4 , the traction systems  34   a ,  34   b  are offset from the central axis of rotation  20  of the drums  12   a ,  12   b . This offset between the central axis of the traction motors  36   a ,  36   b  and the center of the drums  12   a ,  12   b  using slewing gears  38   a ,  38   b  allows the system to directly drive the eccentric assembly  18  along the central axis  20  of the drum  12   a  via the constant velocity joint  58 . 
     The sprung mass  32  further includes a number of other components mounted to the frame  60   a ,  60   b  and that contribute to the mass of the sprung mass  32 . For example, as shown in  FIG. 3 , the sprung mass  32  further includes an engine  54  mounted on the frame, a counterweight  56  mounted on the frame, and/or a bumper  64   a ,  64   b  mounted on the frame  60   a ,  60   b . Water tanks may be mounted in the bumper  64   a ,  64   b  which may also add further mass to the sprung mass  32 . 
     Referring to  FIGS. 5 and 6 , when the surface compactor machine is in the stationary position, the first center of gravity G 1  of the unsprung mass  22  and the second center of gravity G 2  of the sprung mass  32  are in vertical alignment ( FIG. 5 ). 
     When the traction system  34   a ,  34   b  rotates the sprung mass  32  relative to the head plate  24   a ,  24   b  about the axis of rotation  20  (for example, by an angle of rotation A 1  shown in  FIG. 6 ), the second center of gravity G 2  of the sprung mass  32  is rotated out of vertical alignment with the first center of gravity G 1  of the unsprung mass  22 . In the example shown in  FIG. 6 , the second center of gravity G 2  of the sprung mass  32  is rotated out of vertical alignment with the first center of gravity G 1  of the unsprung mass  22 . This rotation of the second center of gravity G 2  of the sprung mass  32  relative to the first center of gravity G 1  of the unsprung mass  22  lifts the second center of gravity G 2  of the sprung mass  32 . The gravitational force on the sprung mass  32  causes an imbalance within the surface compactor machine  10 . As the force of gravity attempts to correct this imbalance by pulling the second center of gravity G 2  of the sprung mass  32  back down beneath the first center of gravity of the unsprung mass  22 , friction between the ground and the cylindrical drum  12   a ,  12   b  imparts torque to the cylindrical drum  12   a ,  12   b , which in turn causes rotation of the cylindrical drum  12   a ,  12   b  in a direction toward the rotated center of gravity of the sprung mass  32 . 
     That is, the rotation imparted to the cylindrical drum  12   a ,  12   b  imparts linear (forward or backward) motion of the cylindrical drum  12   a ,  12   b  in a direction  82  from the first center of gravity G 1  of the unsprung mass  22  toward the second center of gravity G 2  of the sprung mass  32 . 
     Accordingly, a surface compactor machine  10  according to some embodiments includes an unsprung mass  22  having a first center of gravity, the unsprung mass including a cylindrical drum  12   a ,  12   b  including a cylindrical drum shell  14   a ,  14   b  and a cylindrical spool  16   a ,  16   b  disposed within the cylindrical drum shell  14   a ,  14   b  and supporting the cylindrical drum shell  14   a ,  14   b , and a sprung mass  32  rotationally coupled to the cylindrical spool along an axis of rotation  20  of the cylindrical drum shell  14   a ,  14   b  and the cylindrical spool  16   a ,  16   b . The sprung mass  32  has a second center of gravity G 2  that is lower than the first center of gravity G 1  when the surface compactor machine is in a stationary position. The sprung mass  32  includes a traction system  34   a ,  34   b  including a traction motor  36   a ,  36   b  and a slewing gear  38   a ,  38   b  coupled to the traction motor. The traction system  34   a ,  34   b  is configured to rotate the sprung mass  32  relative to the cylindrical spool  16   a ,  16   b  about the axis of rotation  20 . When the surface compactor machine  10  is in the stationary position, the first center of gravity G 1  of the unsprung mass  22  and the second center of gravity G 2  of the sprung mass  32  are in vertical alignment, and when the traction system  34   a ,  34   b  rotates the sprung mass  32  relative to the cylindrical spool  16   a ,  16   b  about the axis of rotation  20 , the second center of gravity G 2  of the sprung mass  32  is rotated out of vertical alignment with the first center of gravity G 1  of the unsprung mass  22 , thereby imparting torque to the cylindrical spool  16   a ,  16   b  that causes rotation of the cylindrical drum  12   a ,  12   b.    
     Accordingly, as described above, the sprung mass  32 , which includes all components other than the drum  12   a ,  12   b  and the eccentric assembly  18 , is connected with the drum  12   a ,  12   b  by a slewing gear  38   a ,  38   b  including slewing bearings. The sprung mass  32  has a center of gravity that is displaced from the center of the slewing bearing. Therefore, gravity works to maintain the designed position of the sprung mass  32  without any additional controls or actuators. Heavy components of the sprung mass, such as an internal combustion engine, generator, ultra capacitors, counterweights, etc., are mounted as low as possible in order to keep the frame  60   a ,  60   b  in a horizontal position without active control. 
     Some embodiments include symmetrical electrical powertrains for both halves of the split drum  12   a ,  12   b . Moreover, each drum  12   a ,  12   b  includes an electrical traction motor  36   a ,  36   b  with a reduction gear  46   a ,  46   b  and slewing gear  38   a ,  38   b  for driving the drum  12   a ,  12   b.    
     To better utilize space inside the drum  14   a ,  14   b , and to protect components from vibrations, the shock isolators  26   a ,  26   b  are mounted directly to the drum spools  16   a ,  16   b.    
     Various elements of the machine could be modified. For example, in some embodiments, the engine  54  and generator could be omitted and the drive motors could be powered from batteries/ultra capacitors and be fully electric. The angular planetary gear  46   a ,  46   b  could be replaced by straight planetary gear provided that the drive motor  36   a ,  36   b  were rotated by 90 degrees. The slewing gear  38   a ,  38   b  could be functionally divided into separate units of bearing and gear with internal engagement. There could also be one wrapping frame  60   a ,  60   b  at the top of the machine  10  with tanks and space for electronics. Gyro stabilization could also optionally be provided. The electrical safety brake could be implemented into the drive motor  36   a ,  36   b  or its function could be performed by inline disc brakes operated with compressed air. Many other such modifications are possible and could be made within the scope of the inventive concepts. 
     While embodiments of the inventive concepts are illustrated and described herein, the device may be embodied in many different configurations, forms and materials. The present disclosure is to be considered as an exemplification of the principles of the inventive concepts and the associated functional specifications for their construction and is not intended to limit the inventive concepts to the embodiments illustrated. Those skilled in the art will envision many other possible variations within the scope of the present inventive concepts. 
     The foregoing description of the embodiments of the inventive concepts has been presented for the purpose of illustration and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above teachings. It is therefore intended that the scope of the inventive concepts be limited not by this detailed description, but rather by the claims appended hereto.