Abstract:
The present invention is directed to a control system for sensing the vibration amplitude on a vibration compacting machine. In addition, the control system modifies the rotational speed of the eccentric assembly based on the vibration amplitude of the eccentric assembly. In one embodiment, the control system modifies the rotational speed of the eccentric assembly to match the optimum speed for the adjusted vibration amplitude when the eccentric assembly is adjusted to increase or decrease the vibration amplitude. Reducing the rotational speed of the eccentric assembly at high vibration amplitudes minimizes wear to each of the load bearing components in the vibration compacting machine resulting in an extended service life for the vibration compacting machine. Similarly, increasing the rotational speed of the eccentric assembly at low vibration amplitudes increases the effectiveness of the vibration compacting machine.

Description:
This application claims priority to U.S. Provisional Application Ser. No. 60/442,336, filed Jan. 24, 2003, the entire contents of which are incorporated herein by reference. 

   BACKGROUND AND FIELD OF THE INVENTION 
   This invention relates to compacting vehicles, and more particularly to vibration mechanisms for such compacting vehicles. 
   Compacting vehicles are generally known and are basically used to compact paved or unpaved ground or “work” surfaces (e.g., asphalt mats, roadway base surfaces, etc.). A typical compacting vehicle includes a frame and one or two vibrating drums rotatably mounted to the frame, the drums compacting the surfaces as the vehicle passes over. Compacting vehicles often include vibration assemblies that generate vibrations and transfer these vibrations through the drum to the work surface. Such vibration assemblies typically include two or more eccentric weights that are adjustable relative to each other in order to vary the amplitude of the vibrations that are generated by rotating the eccentric assembly. 
   SUMMARY OF THE INVENTION 
   In one aspect, the present invention is a vibratory system for a compacting vehicle that includes a frame and at least one compacting drum rotatably connected with the frame. The vibratory system comprises first and second weights each disposed within the drum so as to be rotatable about an axis, at least one of the two weights being adjustably positionable about the axis so as to vary a value of a spacing angle between the two weights. A motor is configured to rotate the first and second weights about the axis. A sensor is configured to sense at least one of the first and second weights. Further, a controller is coupled with the sensor and is configured to determine the value of the spacing angle. The controller is further configured to operate the motor such that the motor rotates the two weights at a rotational speed having a value that is generally directly proportional to the value of the spacing distance. 
   In another aspect, the present invention is a control system for a vibratory mechanism of a compacting vehicle. The vibratory mechanism includes first and second rotatable members and an actuator configured to rotate the members. The control system comprises a sensor configured to sense an spacing angle between the first and second rotatable members and a controller. The controller is coupled with the sensor and is configured to automatically operate the actuator such that the two members rotate at about a first rotational speed when the spacing distance has a first value and alternatively the two members generally rotate at about a second rotational speed when the spacing distance has a second value. The first distance is greater than the second distance and the first speed is greater than the second speed. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The foregoing summary, as well as the detailed description of the preferred embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings, which are diagrammatic, embodiments that are presently preferred. It should be understood, however, that the present invention is not limited to the precise arrangements and instrumentalities shown. 
     In the drawings: 
       FIG. 1  is a perspective view of a compacting vehicle including a vibratory system and related control system in accordance with the present invention; 
       FIG. 2  is an exploded perspective view of a drum assembly of the compacting vehicle shown in  FIG. 1 ; 
       FIG. 3  is a perspective view of the drum assembly shown in  FIG. 2 ; 
       FIG. 4  is view similar to  FIG. 3 , illustrating the drum assembly with the frame removed; 
       FIG. 5  is view similar to  FIG. 4 , illustrating the drum assembly with the drive assembly removed; 
       FIG. 6  is view similar to  FIG. 5 , illustrating the drum assembly with the support shaft removed; 
       FIG. 7  is view similar to  FIG. 6 , illustrating the drum assembly with the hand wheel removed; 
       FIG. 8  is a perspective view of the support shaft shown in  FIG. 5 ; 
       FIGS. 9-11  are schematic views of the eccentric assembly shown in  FIG. 2 , illustrating the relative positions of the inner and outer eccentric weights corresponding to the maximum, intermediate, and minimum vibration amplitudes; and 
       FIG. 12  is a schematic view of a control system of the compacting vehicle shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Certain terminology is used in the following description for convenience only and is not limiting. The words “inner”, “inwardly” and “outer”, “outwardly” refer to directions toward and away from, respectively, a designated centerline or axis, or a geometric center of an element being described, the particular meaning being readily apparent from the context of the description. Further, as used herein, the word “connected” is intended to include direct connections between two members without any other members interposed therebetween and indirect connections between members in which one or more other members are interposed therebetween. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import. 
   Referring now to the drawings in detail, wherein like numbers are used to indicate like elements throughout, there is shown in  FIGS. 1-12  a presently preferred embodiment of a control system  10  for a vibratory mechanism or system  12  for a compacting vehicle  1  in accordance with the present invention. The compacting vehicle  1  basically includes a frame  2  and at least one and preferably two compacting drums  3 A,  3 B rotatably connected with the frame  2 . The vibratory system  12  basically comprises first and second rotatable members or weights  14 ,  16  each disposed within one of the drums  3  so as to be rotatable about an axis  15  and forming an eccentric assembly  17 , as described in further detail below. At least one of the two weights  14 ,  16 , preferably the first weight  14 , is adjustably positionable about the axis  15  so as to vary a value of a spacing angle A S  between the two weights  14 ,  16 , preferably by means of an adjustment mechanism  19 . A motor  18  is configured to rotate the first and second weights  14 ,  16  about the axis  15 , alternatively in either a counterclockwise or clockwise direction, such that vibrations are generated by the rotating weights  14 ,  16 , as discussed below. The amplitude of the vibrations generated by the rotating weights  14 ,  16  is basically inversely proportional to the value of the spacing angle A S , i.e., the greater the spacing angle A S , the lesser the net eccentric moment of the weights  14 ,  16  and the lesser the vibration amplitude, and vice-versa, as described in further detail below. 
   The control system  10  basically comprises a sensor  20  configured to sense at least one of the first and second weights  14 ,  16  and a controller  22  coupled with the sensor  20 . The controller  20  is preferably configured to determine the value of the spacing angle A S  from information provided by the sensor  20 , as discussed below. The controller  22  is further configured to automatically operate or adjust the motor  18  such that the motor  18  rotates the two weights  14 ,  16  at a rotational speed R S  having a value that is generally directly proportional to the value of the spacing angle A S . In other words, the controller  22  is configured to operate the motor  18  such that the motor  18  rotates the two weights  14 ,  16  at about a first, substantially greater rotational speed R S1  (e.g., 4200 rpm) when the spacing angle A S  has a first, relatively greater value A S1  (e.g., 180 degrees). Alternatively, the controller  22  operates the motor  18  such that the motor  18  rotates the two weights  14 ,  16  at about a second, substantially lesser rotational speed R S2  (e.g., 2500 rpm) when the spacing angle has a second, relatively lesser value A S2  (e.g., 0 degrees). As such, the weights  14 ,  16  are rotated at a higher speed when the vibration amplitude is lesser and the weights  14 ,  16  are rotated at a lower speed when the vibration amplitude is greater. 
   Preferably, the sensor  20  is configured to sense when one of the first and second weights  14 ,  16  is disposed (i.e., momentarily during rotation) at a particular angular position P A  ( FIG. 9 ) about the axis  15  and to generate a signal. Alternatively, the sensor  20  may be configured to directly sense or measure the spacing angle A S  between the two weights  14 ,  16 . The controller  22  is configured to determine the value of the spacing angle A S  using the signal(s) from the preferred sensor  20 . More specifically, the sensor  20  is configured to generate one signal when the first weight  14  is temporarily located or disposed at the angular position P A  and another signal when the second weight is temporarily disposed at the angular position P A . In other words, the sensor  20  generate the signals whenever the sensor  20  detects the weights  14 ,  16  as they pass through the angular position P A  when rotating about the axis  15 . The controller  22  also determines the rotational speed of the two weights  14 ,  16  from one of the two signals, preferably the signal generated when the sensor  20  detects the first weight  14 , based upon at least two signals generated by detecting the weight  14  twice as it rotates about the axis  15 , as described in further detail below. Alternatively, the control system  20  may have any another device to measure rotational speed of the weights  14 ,  16 , such as a sensor directly measuring motor shaft speed. Based on the frequency of detecting the two weights  14 ,  16 , the controller  22  is able to calculate the spacing angle A S , as is also discussed further below. 
   Further, the control system  10  preferably further comprises a first reference member  24  connected with the first weight  14  and a second reference member  26  connected with the second weight  16 . The sensor  20  is located at a fixed location on the vehicle  1  with respect to the axis  15  and is configured to generate a signal when either one of the two reference members  24 ,  26  is disposed generally proximal to the fixed location P A  as the weights  14 ,  16  rotate past the sensor  20 . Preferably, each one of the first and second reference members  24 ,  26  is a magnet  60 ,  62 , respectively, and the sensor  20  is a proximity sensor  66  configured to sense the two magnets  60 ,  62 . 
   Furthermore, the controller  22  preferably includes a microprocessor  72  electrically coupled with the sensor  20  and with the motor  18 . The microprocessor  72  has a memory and a reference table stored in the memory, the reference table including a plurality of speed values each corresponding to a separate value of the spacing angle A S . With this arrangement, the microprocessor  72  is configured to select a desired speed value from the reference table based on the sensed spacing angle A S , and to adjust the motor  18  accordingly. In addition, the vibratory system  10  preferably further comprises a pump  5  operatively coupled with the motor  18 , with the controller  22  being operatively connected with the pump  5 . The controller  22  is further configured to adjust the pump  5  so as to thereby adjust rotational speed of the motor  18 , and thus the weights  14 ,  16 . Having discussed the basic components and operation of the present invention, these and other elements of the control system  10  and the vibratory system  12  are described in further detail below. 
   Referring first to  FIG. 1 , the vibratory system  12  is preferably used with a compacting vehicle  1  that includes a frame  2 , a leading drum  3 A, and a trailing drum  3 B, but may alternatively be used with single drum compacting vehicles (not shown). The leading drum  3 A is rotatably mounted to the forward end  2   a  of the frame  2  and the trailing drum  3 B is rotatably mounted to the rearward end  2   b  of the frame  2 . The compacting vehicle  1  also includes an operator&#39;s station  4  that is connected to the frame  2  at a position substantially above and between the leading and trailing drums  3 A,  3 B such that an operator located in the operator&#39;s station  4  is sufficiently elevated above the compacting vehicle  1  to view the area ahead of the leading drum  3 A. 
   The leading and trailing drums  3 A,  3 B are substantially similar, with each drum  3 A,  3 B having a separate eccentric assembly  17  including the two weights  14 ,  16 , as described above and in further detail below. For simplicity&#39;s sake, only the leading drum  3 A and the associated eccentric assembly  17  is described in detail herein. As best shown in  FIG. 2 , the drum  3 A includes one eccentric assembly  17  that is mounted for rotation about the axis  15 , which extends laterally or transversely through the drum  3 A. Rotating the eccentric assembly  17  creates eccentric moments that cause vibrations that are transferred to the drum  3 A. The drum  3 A transfers these vibrations to the ground in order to level paved and unpaved surfaces. 
   The compacting vehicle  1  includes an engine (not shown) that is mounted to the frame  2 . The engine drives two hydraulic pumps  5  that are also mounted to the frame  2 . The first hydraulic pump (not shown) is operably connected to a drive assembly  6  that is connected to one side  30  of the drum  3 A in a conventional manner. The drive assembly  6  includes a hydraulic motor  32  that operates to rotate the drum  3 A relative to the frame  2  to thereby move the compacting vehicle  1  over the ground. The second hydraulic pump  5  ( FIG. 12 ) is operably connected to a drive assembly  7  that is connected to another side  36  of the drum  3 A in a conventional manner. The drive assembly  7  includes the hydraulic motor  18  that rotates the eccentric assembly  17 , and thus the first and second weights  14 ,  16 , relative to the drum  3 A. The second hydraulic pump  5  includes an electronic displacement control  40  (“EDC”) ( FIG. 12 ) that adjusts the flow of hydraulic fluid from the second hydraulic pump  5  to the hydraulic motor  18  rotating the drive assembly  7 . 
   The eccentric assembly  17  further includes a shaft  42  that is mounted at each end to bearings  44 . The bearings  44  are secured to parallel supports  46  that extend across the inner diameter of the drum  3 A. The supports  46  are welded to an interior wall of the drum  3 A and are generally perpendicular to the longitudinal axis of the drum  3 A. 
   Referring to  FIGS. 9-11 , the two weights  14 ,  16  of the eccentric assembly  17  are preferably formed as inner weight  48  and an outer weight  50 , respectively. The inner weight  48  has a generally solid, cylindrical body  49  with an offset portion  49   a  extending radially outwardly from a remainder of the body  49 . The outer weight  50  has a generally tubular body  51  with an offset portion  51   a  extending radially inwardly from a remainder of the body  51  and having a longitudinal central bore  51   b . The inner weight  48  is disposed within the central bore  51   b  of the outer weight  50  such that the two weights  48 ,  50  are radially spaced apart, the two weights  48 ,  50  being releasably connectable so as to be rotatable about the axis  15  as a single unit (i.e., without relative angular displacement). Alternatively, the first and second weights  14 ,  16  may be formed in any other appropriate manner, such as for example, two axially spaced-apart weighted members and/or having other appropriate shapes, and/or may include three or more weights (no alternatives shown). 
   In addition, the inner weight  48  is preferably adjustably positionable, specifically angularly displaceable, relative to the outer weight  50  so as to adjust or vary the vibration amplitude of the eccentric assembly  17 . More specifically, the net moment of eccentricity of the two rotating weights  48 ,  50  is varied or adjusted by adjusting the relative position of the center of mass C 1  of the inner weight  48  with respect to the center of mass C 2  of the outer weight  50 , as indicated in  FIGS. 9-11 . For purposes of illustration, each weight  48 ,  50  may be considered as having a centerline  48   a ,  50   a , respectively, extending perpendicularly between the center of mass C 1 , C 2 , and the axis of rotation  15 . As such, the spacing angle As between the two weights  48 ,  50  is preferably defined as the angle between the two centerlines  48   a ,  50   a  of the inner weight and outer weights  48 ,  50 , respectively. For example,  FIG. 9  illustrates a relative arrangement of the weights  48 ,  50  that results in a maximum vibration amplitude of the eccentric assembly  17 . At the maximum amplitude arrangement, the center of mass C 1 , C 2  of two weights  48 ,  50  are generally radially aligned with each other such that the spacing angle A S2  is about 0 degrees. In contrast,  FIG. 11  depicts a weight arrangement that results in minimum vibration amplitude of the eccentric assembly  17 . At the minimum amplitude setting, the centers of mass C 1 , C 2  of the two weights  48 ,  50  are offset by a spacing angle A S1  of about 180 degrees. Further,  FIG. 10  illustrates an intermediate vibration amplitude of the eccentric assembly  17  where the spacing angle A S3  between the inner and outer weights  48 ,  50  has a value between 0 and 180 degrees. 
   Referring to  FIGS. 2 ,  5  and  6 , the adjustment mechanism  19 , as discussed above, preferably includes a hand wheel  52  coupled with the eccentric assembly  17  and configured to angularly displace the inner weight  48  with respect to the outer weight  50 . When it is desired to adjust the vibration amplitude of the vibratory system  12 , the hand wheel  52  is pulled against a spring bias to disengage the inner weight  48  from a splined connection (not shown) with the outer weight  50 . With the inner weight  48  disengaged, the hand wheel  52  can be rotated to move the inner weight  48  relative to the outer weight  50  to a desired position. The position of the inner weight  48  relative to the outer weight  50  is identified by the location of the hand wheel  52  relative to an indicator  54  that is connected to the outer weight  50  ( FIG. 7 ). The hand wheel  52  can also include identifying indicia  56  to display to the operator the general vibration amplitude of the eccentric assembly  17  relative to the maximum (identified as “8” on indicia  56  in  FIG. 6 ) and minimum (identified as “1” on indicia  56  in  FIG. 6 ). 
     FIG. 12  schematically illustrates the control system  10 , which both senses the vibration amplitude on a compacting vehicle  1  adjusts the rotational speed R S  of the eccentric assembly  17  such that the eccentric assembly  17  to rotate the eccentric assembly  17  at its optimum speed for the adjusted vibration. It is advantageous to operate the eccentric assembly  17  at optimum speeds for all adjusted vibration amplitudes because it allows the eccentric assembly  17  at lower vibration amplitudes to operate at higher speeds to improve the effectiveness of the compacting vehicle  1 , and it reduces the speed of rotation for the eccentric assembly  17  at higher vibration amplitudes to minimize wear to each of the load bearing components in the compacting vehicle  1 . Preferably, the controller  22  is configured to operate the motors  18  of the eccentric assemblies  17  of both drums  3 A,  3 B, as depicted in  FIG. 12 , but the vehicle  1  may alternatively be provided with two separate control systems  10 , each controlling the eccentric assembly  17  of a separate one of the drums  3 A,  3 B. 
   Referring to FIGS.  6  and  9 - 11 , the control system  10  preferably includes a first magnet  60  connected to the indicator  54  that is connected to the outer weight  50 , and a second magnet  62  that is connected to the hand wheel  52  that is connected to the inner weight  48 . As best shown in  FIG. 6 , the hand wheel  52  includes apertures  64  that correspond to each setting identified on the indicia  56 . As the hand wheel  52  is rotated to each position, the corresponding aperture  64  aligns with the magnet  60 . Both magnets  60 ,  62  are generally located at a common radial distance from the axis of rotation  15 . 
   Referring to  FIGS. 5 and 6 , the sensor  20  of the control system  10  is preferably a proximity sensor  66  that is connected to the end of a support shaft  68  so as to located at the fixed angular position P A  with respect to the axis  15 . The support shaft  68  is connected to the frame  2  by any appropriate means, such as bolts  70 , etc. As the eccentric assembly  17  rotates, the sensor  66  generates a signal each time a magnet  60 ,  62  passes the sensor  66 . The sensor  66  generates different signals for the first and second magnets  60 ,  62  as the eccentric assembly rotates the magnets  60 ,  62  past the sensor  66 . The sensor  66  senses the presence of the magnet  60  through the corresponding aperture  64 , while the sensor&#39;s reading of the magnet  62  is unobstructed. 
   Referring again to  FIG. 12 , the preferred microprocessor  72  receives the signals generated by the sensor  66  and interprets the signals to determine the relative positions of the inner and outer weights  48 ,  50 , and thereby the spacing angle A S . As discussed above, the spacing angle A S  is associated with a specific vibration amplitude setting for the eccentric assembly  17 . Based on this calculation, the microprocessor  72  determines the optimal speed for that specific vibration amplitude, preferably by comparing the calculated value of the spacing angle A S  to the stored table of speed values as discussed above, and generates and transmits a signal to the EDC  40  of the pump  5 . The EDC  40  controls the flow of hydraulic fluid to the motor  18  rotating the eccentric assembly  17  thereby controlling the speed of rotation R S  of the eccentric assembly  17 . 
   The control system  10  automatically operates the motor  18  such that the eccentric assembly  17  rotates at the optimum speed based on the particular vibration amplitude of the eccentric assembly  17 . In this regard, the control system  10  enables the compacting vehicle  1  to operate more efficiently because the prior machines either ran continuously at a single speed or required the operator to visually monitor the vibration amplitude setting on the hand wheel  52 , determine the optimum speed of rotation for the eccentric assembly  17  based on the observed setting, and manually adjust and monitor the speed of rotation to match the optimum speed. 
   The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiments described herein are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.