Abstract:
An improved belt tensioning system for an agricultural round baler that increases belt tension to reduce slippage between the belts and the driving rolls during the initial stage of a bale forming cycle when the bale chamber is empty and as the belts are beginning to be rolled. The system includes an accumulator that is pressurized by the tensioning system as a bale is being formed. The accumulator pressure may then be directed to a hydraulic cylinder included in a bale density system to increase tension in the belts after a completed bale is ejected and the bale chamber is being reset for the next bale.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/467,129, entitled “Accumulator System for Round Baler Belt Pre-Tension” and filed May 9, 2012, the contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to agricultural round balers which form cylindrical bales using one or more movable belts and/or rollers disposed in a bale-forming chamber and, more particularly to an improved system for tensioning the movable belts. 
       BACKGROUND OF THE INVENTION 
       [0003]    Round balers have become quite prevalent for their capability of producing a conveniently sized cylindrical bale, very often automatically wrapped with a sheeting material such as net or film. Crop material, such as hay, is picked up from the ground as the baler travels across the field, and is fed into an expandable chamber where it is rolled up to form a compact cylindrical hay package. 
         [0004]    Prior art round balers generally have an expandable bale chamber defined by a pair of fixed sidewalls, and a plurality of side-by-side belts cooperating with a series of transverse rolls, mounted between a pair of pivotally mounted arms commonly known as a sledge. The chamber includes an inlet opening in the front through which crop material is fed. Also included is a pair of take up arms pivotally mounted on the main frame, between which arms multiple of guide rolls are journalled. A biasing force is applied on the take up arms to urge the outer surfaces of the guide rolls against the belts to maintain belt tension and prevent slack from occurring in the belts during expansion and contraction of the chamber. 
         [0005]    It is known to provide a round baler density system to apply increased tension on the belts in order to create a densely packed bale. A hydraulic density cylinder with a controlled fluid release limits the rate of bale chamber expansion and provides a degree of crop compaction during baling. The amount of compaction may be varied by adjusting the fluid release rate, often in the form of a pressure relief valve which restricts the extension of the density cylinder by forcing fluid through a variable relief. When the bale reaches a desired size and is discharged, mechanical springs acting on the take up arms are typically employed to return the hydraulic cylinder to its initial position and provide a biasing force on the take up arms so a new bale forming cycle may commence. 
         [0006]    Problems arise when the baler is used on silage crops which typically have higher moisture content and are suppler. The additional moisture reduces the friction coefficient between the belts and the drive roll. The supple crop has a tendency to build up on the rollers and scrapers in the baler, increasing friction and requiring more power to turn the belts. The combination increases incidence of belt slipping, making the task of commencing the bale-forming cycle by rolling the then-stationary belts all the more difficult. 
         [0007]    It would be desirable to provide a system that would increase the tension in the belts to improve belt rolling during the initial phase of bale formation. Additional advantages would be realized by a system that would selectively increase belt tension during the bale initial phase yet allow use of the current bale density systems once the bale forming process is under way. Still further advantages would be realized through an improved belt tensioning system that could be easily implemented on existing bale tensioning systems without requiring a dramatic changes to the bale tensioning system. 
       SUMMARY OF THE INVENTION 
       [0008]    Accordingly, the present invention, in any of the embodiments described herein, may provide one or more of the following advantages: 
         [0009]    It is an object of the present invention to provide an improved belt tensioning system for an agricultural round baler that increases belt tension during the initial stage of a bale forming cycle when the bale chamber is empty and as the belts are beginning to be rolled. 
         [0010]    It is a further object of the present invention to provide an improved belt tensioning system for an agricultural round baler that is selectively adjustable to suit a variety of operating conditions caused by various crop materials. 
         [0011]    It is a further object of the present invention to provide an improved belt tensioning system for an agricultural round baler that does not interfere with the core forming portion of the bale forming cycle. 
         [0012]    It is a further object of the present invention to provide an improved belt tensioning system for an agricultural round baler that is easily retrofit onto existing round balers having bale density systems. 
         [0013]    It is a still further object of the present invention to provide an improved belt tensioning system for an agricultural round baler having a bale density system that is durable in construction, inexpensive of manufacture, carefree of maintenance, easily assembled, and simple and effective to use. 
         [0014]    These and other objects are achieved according to the instant invention by providing an improved belt tensioning system for an agricultural round baler that increases belt tension to reduce slippage between the belts and the driving rolls during the initial stage of a bale forming cycle when the bale chamber is empty and as the belts are beginning to be rolled. The system includes an accumulator that is pressurized by the tensioning system as a bale is being formed. The accumulator pressure is then directed to a hydraulic cylinder included in a bale density system to increase tension in the belts after a completed bale is ejected and the bale chamber is being reset for the next bale. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    For the purpose of illustration, there are shown in the drawings certain embodiments of the present invention. It should be understood, however, that the invention is not limited to the precise arrangements, dimensions, and instruments shown Like numerals indicate like elements throughout the drawings. In the drawings: 
           [0016]    The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
           [0017]      FIG. 1  is a perspective view of a typical agricultural round baler on which the present invention is useful; 
           [0018]      FIG. 2  is a side section view of the round baler of  FIG. 1  showing a bale forming chamber configured at the beginning of a bale forming cycle; 
           [0019]      FIG. 3  is a side view of the agricultural round baler in  FIG. 1  in which the bale forming chamber is configured as it would be near the end of a bale forming cycle; 
           [0020]      FIG. 4  is a diagrammatic view of a bale tension system incorporating the present invention shown configured as it would be during the initial bale formation in the chamber; 
           [0021]      FIG. 5  is a diagrammatic view of a bale tension system incorporating the present invention shown configured as it would be as the bale formation is progressing (bale growth phase) and the accumulator has been fully charged; 
           [0022]      FIG. 6  is a diagrammatic view of a bale tension system incorporating the present invention shown configured as it would be after the bale has been ejected from the bale forming chamber and the belt tension arms are retracting; and 
           [0023]      FIG. 7  is a diagrammatic view of a bale tension system incorporating the present invention shown configured as it would be after the bale has been ejected from the bale forming chamber and the belt tension arms have fully retracted and pre-tensioning of the belts is applied. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art, and they will not therefore be discussed in significant detail. Also, any reference herein to the terms “left” or “right” are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel. Likewise, “forward” and “rearward” are determined by the normal direction of travel. “Upward” and “downward” orientations are relative to the ground or operating surface as are any references to “horizontal” or “vertical” planes. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application of any element may already be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures. 
         [0025]    Referring to the figures, a generally well-known round baler  10  which incorporates the preferred embodiment of the present invention, includes a main frame  11  supported by a pair of wheels  14  (only one shown). A tongue  12  is provided for connection to a tractor. Pivotally connected to the sides of main frame  11  is tailgate  13  which may be closed (as shown in  FIG. 1 ) during bale formation or pivoted open by tailgate actuator  19  to discharge a completed bale. A conventional pickup  16 , mounted on main frame  11 , includes a plurality of tines  17  movable in a predetermined path to lift crop material from the ground and deliver it rearwardly toward a rotatably mounted floor roll  18 . 
         [0026]    A chamber  20  for forming bales is defined partly by a sledge assembly  30  comprising a plurality of rollers  31 ,  32  extending transversely in the arcuate arrangement shown in  FIGS. 2 and 3 . Rollers  31 ,  32  are journalled at their ends in a pair of spaced apart arms  35 , one of which is shown. These arms are pivotally mounted inside main frame  11  on stub shafts for providing movement of sledge assembly  30  between the bale starting position shown in  FIG. 2  and the full bale position shown in  FIG. 3 . Rollers  31 ,  32  are driven in a clockwise direction by conventional means (i.e., chains and sprockets or gears) connected to and powered by a prime mover via a drive shaft  15 . A freely rotatable idler roller  33  is also carried by arms  35 . Additionally, a starter roll  37 , and a fixed roll  38  are located adjacent to roller  31 , and are also driven in a clockwise direction by the conventional means. 
         [0027]    The bale forming chamber is further defined by an apron  40  comprising a plurality of continuous side-by-side belts supported by guide rolls  43 ,  44 ,  45 ,  46 ,  47  rotatably mounted in tailgate  13  and a drive roll  48 , mounted on main frame  11 . Apron  40  passes between roller  32  on sledge assembly  30  and idler roller  33 , and is in engagement only with idler roller  33  and not roller  32  which is located in close proximity to the apron belts to strip crop material from the belts, in addition to its bale forming function. Drive roll  48  is powered via a power take-off from the tractor and a drive train (not shown) which moves apron  40  along its changing path, indicated generally by arrows A and B in  FIGS. 2 and 3 . An additional guide roll  49  ensures proper driving engagement between apron  40  and drive roll  48 . 
         [0028]    A pair of take up arms  51  (only one shown) are mounted to pivot conjointly with a cross shaft  52  between inner and outer positions, shown in  FIGS. 2 and 3 , respectively, and carry additional guide rolls  53 ,  54  for supporting apron  40 . Belt tension lever arm  55  is also affixed to shaft  52  to pivot with take up arms  51 . A return spring  60  is secured between the baler chassis  11  and tension lever arm  55  to bias the shaft  52  and take up arms  51  toward the bale starting position (shown in  FIG. 2 ) and move the take up arms toward the bale starting position following ejection of a completed bale. A hydraulic bale tension cylinder  56  is mounted between tailgate  13  and take up arms  51  and configured to resist movement of the take up arms from the bale starting position ( FIG. 2 ) toward the full bale position ( FIG. 3 ). 
         [0029]    Rounds balers including belt take-up and tensioning apparatus of the aforementioned type are well known in the art. Exemplar take-up apparatus are described in U.S. Pat. Nos. 4,870,812 and 5,367,865, both to Jennings et al., each being incorporated herein by reference. 
         [0030]    Now turning to  FIGS. 4 through 7  to describe in further detail the novel apron tensioning system  100  at the heart of the present invention. The elements are shown just as the bale formation begins in  FIG. 4 , an intermediate bale formation position where the pre-tension system  100  is charged and ready for operation in  FIG. 5 , a full bale position just after the bale has been ejected in  FIG. 6 , and the apron pre-tensioning with the bale chamber in the empty, ready to begin bale formation position in  FIG. 7 . 
         [0031]    Apron tensioning system  100  comprises a closed hydraulic loop including the hydraulic tension cylinder  56  acting on the take up arms  51  via belt tension lever arms  55 . The hydraulic system includes hoses  107  supplying fluid to both high-side  101  (rod end) and low-side  103  (base end) sides of a piston  561  mounted on a rod  562  in cylinder  56 , an adjustable relief valve  104  with a return free flow check valve  102 . A pre-tension accumulator reservoir  110  is connected to the hose  107  by a solenoid-operated check valve  108 , the check valve  108  being positionable to align a check valve or an open port allowing reverse flow (flow from the accumulator  110 ). The accumulator reservoir  110  is preferably a conventional gas-charged hydraulic accumulator with provisions for altering the gas pressure. A pressure indicator  120  is provided to allow an operator to adjust the relief valve  104  by an adjuster  105  to a desired pressure in the system  100  corresponding to a desired density of the resultant bales. 
         [0032]    In  FIG. 4 , hydraulic fluid is forced from the high-side connection  101  into hoses  107  and the tension cylinder is extended in the direction of arrow E as the bale begins forming in the bale chamber. Charge pressure in the accumulator reservoir  110  is relatively low, so fluid passes through check valve  108  and increases the fluid volume and pressure in the reservoir  110 , generally noted as oil flow path arrows  0 . As the forming bale expands, tension cylinder  56  extends in the direction of arrow E, continuing to force fluid into the system from the high-side  101  connection increasing pressure therein. 
         [0033]    In  FIG. 5 , the hydraulic pressure in system  100  has increased to the selected pressure setting of relief valve  104  which then allows fluid to pass from the high side  101  to the low-side  103  connection of the tension cylinder  56 , shown as arrows  0  in the figure. Pressure in the accumulator reservoir  110  is maintained by operation of the check valve  108  which prevents blow-down of reservoir  110  to the low-side of the tension cylinder  56 . It is to be noted that the range of set pressures for relief valve  104  must exceed the target pressure of the accumulator reservoir  110  in order for movement of the tension cylinder  56  to recharge the accumulator reservoir  110  prior to returning fluid to the low side  103  of the tension cylinder  56 . 
         [0034]      FIG. 6  shows the baler just after the bale has been ejected. Return spring  60  is returning belt tension lever arms  55  and take up arms  51  to the empty, or bale initiating position, and retracting tension cylinder  56  in the direction of arrow R. Hydraulic fluid pressure is now higher on the base end  103  than the rod end  101 . Return check valve  102  allows fluid to pass from the higher pressure base end  103  to the lower pressure rod end  101  (oil flow arrows  0 ) so that the tension cylinder  56  may be retracted. 
         [0035]    In  FIG. 7 , the bale chamber is empty and ready to initiate the next bale cycle. A control signal is sent to solenoid operated check valve  108  to reposition the valve to the open alignment and allow the pressurized fluid in the accumulator reservoir  110  to be directed toward the high side (rod end) of the tension cylinder  56 , again shown as oil flow arrows  0 . The increased pressure on the high side of tension cylinder  56  increases the retraction force on the belt tension lever arms  55  and take up arms  51  beyond that provided by return springs  60  thereby further increasing tension in the apron  40 . The additional belt tension reduces the incidence of belt slipping, especially during the period when the drive roller  48  is working to initiate movement of the apron belts from rest, such as following bale ejection. 
         [0036]    It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. 
         [0037]    These and other advantages of the present invention will be apparent to those skilled in the art from the foregoing specification. Accordingly, it is to be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. It is to be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention.