Patent Abstract:
The vibration compacting machine includes a frame, a leading drum and a trailing drum. The leading and trailing drums are rotatably mounted to the frame. The leading drum includes a first eccentric assembly that is rotatably mounted inside of the leading drum and the trailing drum includes a second eccentric assembly that is rotatably mounted inside the trailing drum. A first motor rotates the first eccentric assembly and a second motor rotates the second eccentric assembly. Rotations of the eccentric assemblies transfers vibrations to the drums to compact a ground surface. A control adjusts the speed of the first and second motor relative to one another to keep the first eccentric assembly from running in phase with the second eccentric assembly. The control also delays starting the second eccentric assembly relative to the first eccentric assembly to minimize horsepower drain on the engine of the vibration compacting machine.

Full Description:
FIELD OF THE INVENTION  
         [0001]    The invention relates to vibration compacting machines, and more particularly to an apparatus and method for controlling the start times and phase relationship between eccentric assemblies within the compacting drums on a double drum vibration compacting machine.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vibration compacting machines are used for compacting paved or unpaved ground surfaces. A typical vibration compacting machine includes leading and trailing ground-engaging drums that are rotatably mounted to a frame of the vibration compacting machine. The ground-engaging drums commonly include an eccentric assembly that is mounted inside of each drum such that rotation of the individual eccentric assemblies produces vibrations that are transferred to the respective drums. The individual eccentric assemblies are usually rotatably driven by separate hydraulic motors that are supplied with hydraulic oil from a common hydraulic pump which is powered by the engine of the vibration compacting machine.  
           [0003]    Since the two eccentric assemblies are driven by separate motors, the eccentric assemblies are not synchronized with each other and rotate at different speeds. As a result of rotating the eccentric assemblies at different speeds, the eccentric assemblies move in and out of phase relative to one another. When the eccentric assemblies are in phase with each other, or nearly in phase with each other, the eccentric assemblies emit an amplified noise that is offensive to an operator of the vibration compacting machine. An in-phase relationship between the eccentric assemblies also creates excessive vibrations that are transferred to the machine frame and the operator&#39;s station.  
           [0004]    U.S. Pat. No. 3,871,788 discloses a vibration compacting machine that has the eccentric assemblies mounted outside of the drums to produce vibrations that are transferred to the drum. The eccentric assemblies each include eccentric weights that are mounted above each drum and rotatably driven by a single motor. The eccentric assemblies are coupled together for synchronized rotation approximately 180° apart from each other. The single motor rotates both eccentric assemblies outside of the drums because the eccentric assemblies are coupled together with a simple mechanical linkage. Coupling the eccentric assemblies together fixes a constant phased relationship between the rotating eccentric assemblies.  
           [0005]    Conventional vibration compacting machines include motors that simultaneously initiate driving the eccentric assemblies resulting in undesirable effects such as (i) a momentary reduction of engine speed; (ii) a discharge of black smoke from the engine exhaust indicating horsepower demand that exceeds available horsepower; (iii) a slowing down of the vibration compacting machine rolling speed; and (iv) a repetitive engagement and disengagement of vibration due to the rolling speed fluctuation.  
           [0006]    The above-described devices are generally effective for creating vibrations and transferring the vibrations to the drums. Therefore, any improvement to such devices would be desirable.  
         SUMMARY OF THE INVENTION  
         [0007]    The vibration compacting machine of the present invention enhances operator comfort by providing a phase control system that prevents a first eccentric assembly which is positioned within a leading drum from rotating in phase with a second eccentric assembly which is positioned within a trailing drum. Preventing in phase rotation reduces undesirable noise levels and vibrations that are communicated to the operator&#39;s station during operation of the vibration compacting machine. The present invention also extends the service life of the vibration compacting machine by minimizing the transfer of potentially damaging vibrations to unprotected components on the vibration compacting machine.  
           [0008]    The vibration compacting machine of the present invention increases engine efficiency by providing a control system that delays starting of one motor until after the power demand caused by starting another motor has peaked and dropped. Delaying the startup of one motor relative to another (i) optimizes the horsepower demand on the engine of the vibration compacting machine; (ii) reduces the frequency and intensity of engine power surges; (iii) increases the operating cycles of the vibration compacting machine before refueling; and (iv) extends the service life of the engine by preventing the engine from operating under peak load.  
           [0009]    The present invention is directed to a vibration compacting machine for leveling paved or unpaved ground surfaces. The vibration compacting machine includes a frame, and a leading and trailing drum that are rotatably mounted to the frame. The leading drum includes a first eccentric assembly that is rotatably mounted inside of the leading drum and the trailing drum includes a second eccentric assembly that is rotatably mounted inside the trailing drum. A first motor rotates the first eccentric assembly to generate vibrations that are transferred to the leading drum and a second motor rotates the second eccentric assembly to generate vibrations that are transferred to the trailing drum. Transferring vibrations to the leading and trailing drums facilitates compacting the ground that the vibration compacting machine is riding on.  
           [0010]    A control adjusts the speed of the first motor and the second motor relative to one another to keep the first eccentric assembly from running in phase with the second eccentric assembly. Keeping the first and second eccentric assemblies from running in phase prevents the eccentric assemblies from (i) emitting an amplified noise that is offensive to the operator; and (ii) transferring excessive vibrations to the operator&#39;s station through the frame of the vibration compacting machine.  
           [0011]    The present invention is also directed to a vibration compacting machine that includes a frame, a leading drum and a trailing drum. The leading and trailing drums are rotatably mounted to the frame and engage the ground that the vibration compacting machine is riding on. The leading drum includes a first eccentric assembly that is rotatably mounted inside the leading drum and the trailing drum includes a second eccentric assembly that is rotatably mounted inside the trailing drum. The first eccentric assembly is driven by a first motor and the second eccentric assembly is driven by a second motor. A control delays the startup of one of the first and second motors for a period of time after starting the other of the first and second motors. Delaying startup of the motor (i) optimizes the horsepower requirement of the engine; (ii) reduces the frequency and intensity of engine power surges; (iii) extends the operating cycles of the vibration compacting machine before refueling is required; and (iv) extends the service life of the engine of the vibration compacting machine by preventing the engine from operating under peak load.  
           [0012]    The present invention also relates to a method for controlling the phase relationship between a first eccentric assembly that is mounted within a leading drum and a second eccentric assembly that is mounted within a trailing drum, the method comprising: driving the first eccentric assembly with a first motor; driving the second eccentric assembly with a second motor; and adjusting the speed of the first motor relative to the second motor to keep the first and second eccentric assembly from moving in-phase with one another.  
           [0013]    In another form, the present invention includes a method for controlling the phase relationship between a first eccentric assembly that is mounted within a leading drum and a second eccentric assembly that is mounted within a trailing drum and driven in series with the first eccentric assembly by a hydraulic pump, the method comprising: driving the first eccentric assembly with a first motor; driving the second eccentric assembly with a second motor; sensing the first and second eccentric assemblies; and adjusting the speed of the first motor relative to the second motor by bypassing hydraulic oil from one of the first and second motors to the other of the first and second motors to keep the first and second eccentric assembly from moving in-phase with one another.  
           [0014]    The present invention is also directed to a method of minimizing horsepower drain when initiating vibrations in a vibration compacting machine, the method comprising: driving a first eccentric assembly that is mounted within a leading drum on the vibration compacting machine by starting a first motor; and driving a second eccentric assembly that is mounted within a trailing drum on the vibration compacting machine by starting a second motor after the first motor has started.  
           [0015]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view illustrating a vibration compacting machine of the present invention.  
         [0017]    [0017]FIG. 2 is a partially sectioned side view illustrating an in-phase condition.  
         [0018]    [0018]FIG. 3 is a view similar to FIG. 2 illustrating an out-of-phase condition.  
         [0019]    [0019]FIG. 4 is a schematic view illustrating a control system and a single hydraulic pump of the vibration compacting machine of FIG. 1.  
         [0020]    [0020]FIG. 5 is a view similar to FIG. 4 illustrating a control system with first and second hydraulic pumps. 
     
    
       [0021]    Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of “consisting of” and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order.  
       DETAILED DESCRIPTION  
       [0022]    [0022]FIG. 1 illustrates a vibration compacting machine  10  of the present invention. The vibration compacting machine  10  includes a frame  12 , a leading drum  14  and a trailing drum  16 . The leading drum  14  is rotatably mounted to the forward end of the frame  12  and the trailing drum  16  is rotatably mounted to the rearward end of the frame  12 . The vibration compacting machine  10  also includes an operator&#39;s station  18  that is connected to the frame  12  at a position substantially above and between the leading and trailing drums  14 ,  16  such that an operator located in the operator&#39;s station  18  is sufficiently elevated above the vibration compacting machine  10  to view the area ahead of the leading drum  14 . It should be noted that although the positions of the leading drum and the trailing drum are illustrated and described in relation to the vibration compacting machine moving in the forward direction, the positions of the leading drum and the trailing drum would be reversed if the vibration compacting machine was being operated in a reverse direction.  
         [0023]    Referring now also to FIGS. 2 and 3, the leading drum  14  includes a first eccentric assembly  20  that is mounted for rotation about an axis  22 A within the leading drum  14 . The trailing drum  16  includes a second eccentric assembly  24  that is mounted for rotation about an axis  22 B within the trailing drum  16 . Rotating the first and second eccentric assemblies  20 ,  24  creates eccentric moments that cause vibrations which are transferred to the respective leading and trailing drums  14 ,  16 . The leading and trailing drums  14 ,  16  transfer these vibrations to the ground in order to level paved and unpaved surfaces.  
         [0024]    Each eccentric assembly  20 ,  24  includes a shaft  26 A,  26 B and an eccentric weight  28 A,  28 B. The eccentric weights  28 A,  28 B are coupled to the shaft  26 A,  26 B such that a center of gravity  30 A,  30 B of each eccentric assembly  20 ,  24  is located a distance from the axis of rotation  22 A,  22 B. As used herein, the position of each center of gravity  30 A,  30 B with respect to the axis of rotation  22 A,  22 B will designate the angular or phase position of the eccentric assembly  20 ,  24 . When each center of gravity  30 A,  30 B is directly below the respective axis of rotation  22 A,  22 B, the phase position of the eccentric assembly  20 ,  24  is 0 degrees and when each center of gravity  30 A,  30 B is directly above the respective axis of rotation  22 , the phase position is 180 degrees.  
         [0025]    As shown schematically in FIG. 4, the vibration compacting machine  10  includes an engine  32  that is mounted to the frame  12 . The engine  32  drives a hydraulic pump  34  that is also mounted to the frame  12 . The hydraulic pump  12  supplies hydraulic oil to a first hydraulic motor  36  that drives the first eccentric assembly  20  and a second hydraulic motor  38  that drives the second eccentric assembly  24 . The second hydraulic motor  38  is connected in series with the first hydraulic motor  36 . The first and second hydraulic motors  36 ,  38  are preferably mounted within the leading and trailing drums  14 ,  16  and rotate the first and second eccentric assemblies  20 ,  24  such that the first and second eccentric assemblies  20 ,  24  generate vibrations which are transferred to the drums  14 ,  16 .  
         [0026]    The first and the second eccentric assemblies  20 ,  24  are driven separately by the hydraulic motors  36 ,  38  such that the first and second eccentric assemblies  20 ,  24  rotate at different speeds. Since the motors  36 ,  38  are connected in series, the speed of the upstream motor  38  is greater than the speed of the downstream motor  36  because the downstream motor  36  has increased losses compared to the upstream motor  38 . The unequal speeds of the first and second eccentric assemblies  20 ,  24  cause the first and second eccentric assemblies  20 ,  24  to consistently move in and out of phase with each other.  
         [0027]    The words “in phase” are used herein to designate that the first eccentric assembly  20  and the second eccentric assembly  24  are located in substantially the same phase position. As shown in FIG. 2, the eccentric assemblies  20 ,  24  are in phase because both eccentric assemblies  20 ,  24  are located in the 0 degree position such that there is a 0 degree difference between the eccentric assemblies  20 ,  24 . The phrase “out of phase” is similarly used to designate that the first and second eccentric assemblies  20 ,  24  are located at different phase positions. As shown in FIG. 3, the first and second eccentric assemblies  20 ,  24  are out of phase because the first eccentric assembly  20  is located at the 0 degree position and the second eccentric assembly  24  is located at the 180 degree position such that a 180 degree angle exists between them.  
         [0028]    Several problems develop from rotating the eccentric assemblies  20 ,  24  in phase, or nearly in phase, with each other. First, the eccentric assemblies  20 ,  24  emit an amplified noise that is offensive to the operator positioned at the operator&#39;s station  18 . In addition, the eccentric assemblies  20 ,  24  transfer significant vibrations to the operator station  18  of the vibration compacting machine  10  through the frame  12 . The increased vibrations cause discomfort to the operator and decrease the machine component life of mechanical and electronic systems on the vibration compacting machine  10  that are sensitive to shock and vibration.  
         [0029]    Referring again to FIG. 4, the vibration compacting machine  10  includes a phase control system  40  that monitors the eccentric assemblies  20 ,  24  and maintains the eccentric assemblies  20 ,  24  in an out of phase position to reduce the effect of the above mentioned problems. The phase control system  40  includes a first sensor  42  that produces an input signal corresponding to the location of the first eccentric assembly  20 , and a second sensor  44  that produces an input signal corresponding to location of the second eccentric assembly  24 . The sensors  42 ,  44  preferably sense the speed of the first and second eccentric assemblies  20 ,  24  and the phase relationship between the first and second eccentric assemblies  20 ,  24  using a sensor such as a Hall Effect sensor or a variable reluctance sensor. The sensors  42 ,  44  may also sense the acceleration of the first and second eccentric assemblies  20 ,  24  with an accelerometer. Alternatively, the sensors  42 ,  44  can sense the volume of the sound generated by the first and second eccentric assemblies  20 ,  24  with a microphone. It should be noted that a single microphone could be used to monitor the volume of the eccentric assemblies  20 ,  24  when the microphone is positioned between the drums  14 ,  16 , preferably near the operator&#39;s station  18 .  
         [0030]    The vibration compacting machine  10  also includes a control  46  that varies the speed of the first and second motor  36 ,  38  relative to each other to move the eccentric assemblies  20 ,  24  out of phase based on information received from the input signals of the sensors. The control  46  adjusts the speed of the first and second motors  36 ,  38  by sending an output signal that opens a bypass valve  48  to allow hydraulic oil to bypass the second hydraulic motor  38  and travel directly to the first hydraulic motor  36 . As hydraulic oil bypasses the second hydraulic motor  38 , the first hydraulic motor  36  increases speed and the second hydraulic motor  38  decreases speed such that the eccentric assemblies  20 ,  24  move toward a more out of phase position.  
         [0031]    The control  46  is preferably a microprocessor that determines whether or not the phased relationship between the eccentric assemblies  20 ,  24  are within acceptable predetermined limits. The control  46  also determines the rate the phased relationship is moving away from the nominal acceptable limit or towards the nominal acceptable limit. Based on this information, the control  46  delivers an output signal to modify the phased relationship of the eccentric assemblies  20 ,  24 . The control  46  tracks the effects of the signals on the eccentric assemblies  20 ,  24  so that an improved change can be made in the future for a similar phased relationship. The control  46  repeats this iterative process such that the control  46  realizes an ideal output signal for each phased relationship between the eccentric assemblies  20 ,  24 . The control  46  stores these ideal output signals for each individual machine in order to optimize all of the output signals for that specific vibration compacting machine  10 .  
         [0032]    The control  46  preferably delays startup of the second hydraulic motor  38  for a period of time after starting the first hydraulic motor  36  in order to reduce the negative effects of excessive engine horsepower drain that results when both hydraulic motors  36 ,  38  are started simultaneously. In one of many forms, the phase control system  40  includes a first valve  50  that is positioned between the hydraulic pump  34  and the second hydraulic motor  38  and a bypass valve  48  that is positioned between the hydraulic pump  34  and the first hydraulic motor  36  along a fluid path which bypasses the second hydraulic motor  38 . During startup of the eccentric assemblies  20 ,  24 , the first valve  50  is closed and the bypass valve  48  is opened to supply hydraulic oil to the first hydraulic motor  36  to initiate rotation of only the first eccentric assembly  20 . After a defined period of time, the first valve  50  is opened to begin rotation of the second hydraulic motor  38  along with the first hydraulic motor  36 . The start up of the second hydraulic motor  38  is preferably delayed. The appropriate timing for the delay is determined by the base distance between the drums  14 ,  16  and the rolling speed of the vibration compacting machine. The trailing drum&#39;s vibrations are preferably initiated at the same location on the pavement surface as the location that the leading drum began generating vibrations.  
         [0033]    The control  46  assures that the horsepower requirement on the compactor&#39;s engine  32  will be optimized since the leading drum&#39;s  14  power demand from the engine  32  will have peaked and dropped before power is required for the trailing drum  16 . The method and vibration compacting machine  10  of the present invention (i) reduce total peak engine  32  horsepower; (ii) extend engine  32  life due to diminished operation under peak power load; (iii) increase operating cycles of the vibration compacting machine before refueling is required; and (iv) reduce the frequency and intensity of engine  32  power surges.  
         [0034]    [0034]FIG. 5 illustrates an alternative form of the invention that includes an engine  32 , and first and second hydraulic pumps  52 ,  54  that are independently driven by the engine  32 . The first hydraulic pump  52  supplies hydraulic oil to the first hydraulic motor  36  and the second hydraulic pump  54  supplies hydraulic oil to the second hydraulic motor  38 . In this embodiment, the control  46  independently adjusts flow of hydraulic oil to the first and second hydraulic pumps  52 ,  54  in order to control the speed of the first eccentric assembly  20  independently from speed of the second eccentric assembly  24 . The control  46  also delays the startup of the second hydraulic motor  38  until after the first hydraulic motor  36  is started by preventing the flow of hydraulic oil from the second hydraulic pump  54  to the second hydraulic motor  38 . In an alternative form, the control  40  delays the startup of the first hydraulic motor  36  until after the second hydraulic motor  38  is started by preventing the flow of hydraulic oil from the first hydraulic pump  52  to the first hydraulic motor  36 .

Technology Classification (CPC): 4