Abstract:
A control mechanism for the feed of a brush chipper is disclosed. A lower feed stop bar, located under a feed table, pivots on a pivot axis located below and toward the brush chipper from the control bar of the lower feed stop bar. The center of gravity of the lower feed stop bar, then, tends to pivot the lower feed stop bar away from the feed disengage position. Hence, nuisance trips due to vibration, impact of brush on the table, etc., are reduced.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    This invention relates to feed control for a brush chipper. More particularly, the invention relates to a method and apparatus for providing a lower feed stop bar that reduces nuisance trips. 
         [0006]    2. Background Art 
         [0007]    Control aspects of brush chippers are provided for control and safety of machinery and operators. One control aspect, a lower feed stop bar, is located at an infeed side of an infeed table or shelf on the brush chipper. It is situated such that an operator may stop the feed of brush for any reason by pushing the lower feed stop bar toward the brush chipper. Present day feed stop bars are typically pivoted from pivot arms at each end of a control bar. The control bar extends across the infeed end of the infeed table. In the known art, the pivot arms extend upward from the control bar and the axis of rotation is above and toward the outfeed end of the brush chipper more than the control bar. 
         [0008]    The force of gravity, aggravated by machine vibrations, tends to force the lower feed stop bar toward its forward position, thereby causing nuisance trips. 
         [0009]    The infeed table of a brush chipper is subjected to significant vertical accelerations that occur when loading branches/logs onto the feed table. When a log is dropped onto the table it moves downward, stops and then moves upward. As the downward movement starts the feed table and the feed stop bar are subjected to a negative acceleration, wherein the feed stop bar will tend to rotate clockwise if the pivot axis is to the left of the mass of the feed stop bar as shown in FIGS. 1 and 2 of U.S. Patent Application Ser. No. 2004/0108397, for example, and would tend to rotate counter-clockwise if the pivot axis was to the right of the mass of the feed stop bar. As the feed table is moving downward, the tires and suspension of the machine are being compressed, and eventually the movement changes direction, and energy stored in the tires and suspension cause the machine to move upwards. During this upward movement, when the direction is reversed, the feed stop bar is subject to acceleration in an opposite direction. Having the design of the feed stop bar, including the position of the pivot axis to the left of the mass of the stop bar, as shown in FIGS. 1 and 2 of No. U.S. Patent Application Ser. No. 2004/0108397, has been observed to result in false trips due to the dynamic loading, the acceleration of the feed table previously described. 
         [0010]    U.S. Pat. Nos. 5,692,548 by Bouwers et al. and 5,692,549 by Eggers are hereby incorporated by reference and disclose brush chippers having many components of the brush chippers on which the present invention is used. Some of the pertinent components are: a material inlet, or feed table assembly, a plurality of feed rollers, and a chipping drum. The feed rollers are driven by hydraulic motors. 
         [0011]    There is, therefore, a need for a method and apparatus for a lower feed stop bar pivoted and oriented in a fashion to reduce the possibility of nuisance trips while providing all the functionality of lower feed stop bars in the prior art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    It is an object of the present invention is to provide a lower feed stop bar for a brush chipper having fewer nuisance trips than lower stop bars of the prior art. To effect this object, the lower feed stop bar is provided with an axis of rotation or pivot located below the control bar and towards the brush chipper relative to the control bar. Configured in this fashion, the center of mass of the lower feed stop bar resides away from the brush chipper relative to the axis of rotation. Hence, gravity tends to rotate the lower feed stop bar in a direction opposite that under which the brush feed will be caused to cease. 
         [0013]    In the preferred embodiment, a spring or other elastic member provides further force to rotate the lower feed stop bar in a direction opposite that under which the brush feed will be caused to cease. 
         [0014]    An additional object of this invention is to provide a mechanical safety system that positions the lower feed stop bar in its tripped position when the infeed table is folded up into its folded position against the brush chipper. The infeed table is often placed in its folded position for transport of the brush chipper from one area to another. By assuring the feed has ceased, the brush chipper is in a safer and more efficient mode for transport. 
         [0015]    The stated and other objects will be made clear by reference to the drawings and detailed description of the invention. 
         [0016]    The present invention has resulted in an unexpected result of having fewer false trips. This is believed to be due to the fact that positive acceleration of the feed table, as it stops moving downward, and starts moving upward, is greater than the negative acceleration as it initially moves downward. 
         [0017]    One significant aspect of the preferred embodiment of the present invention is the fact that the machine is mounted on a trailer with a suspension and with rubber tires. It is theorized that this is the reason that the maximum acceleration occurs when the feed table changes direction from downward to upward following a log being dropped on the infeed table and this is at least partially why this invention is effective. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is an isometric of a brush chipper with a feed table in a lowered position; 
           [0019]      FIG. 2  is an isometric of the brush chipper with the feed table in a raised position; 
           [0020]      FIG. 3  is an isometric of the feed table with the bottom feed stop bar in a fully extended position; 
           [0021]      FIG. 4  is a detailed cross section of the bottom feed stop bar in the fully extended position showing a spring; 
           [0022]      FIG. 5  is a detailed cross section of the bottom feed stop bar in a normal sensitivity position with the spring deleted, showing a switch; 
           [0023]      FIG. 6  is a detailed cross section of the bottom feed stop bar in a reduced sensitivity position with the spring deleted, showing the switch; 
           [0024]      FIG. 7  is a side elevation view of the feed table, the bottom feed stop bar in a normal position, the feed table lowered; 
           [0025]      FIG. 8  is a side elevation view of the feed table, the feed table raised to the transport position; and 
           [0026]      FIG. 9  is a flow chart showing logic for controlling a feed of the brush chipper with the lower feed stop bar. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    With reference now to the various figures in which identical elements are numbered identically throughout, a description of various exemplary aspects of the present invention will now be provided. The preferred embodiments are shown in the drawings and described with the understanding that the present disclosure is to be considered an exemplification of the invention and is not intended to limit the invention to the embodiments disclosed. 
         [0028]    A brush chipper  10 , illustrated with the lower feed stop bar  100  of the present invention, is shown in  FIGS. 1 and 2 . Besides the lower feed stop bar  100 , the brush chipper comprises a feed table  110  having perpendicular sides  120  for structural support and for guiding brush into the brush chipper  10 . As illustrated in published U.S. Patent Application No. 2004/0108397, which is hereby incorporated in its entirety by reference, inside the brush chipper  10  are two feed rollers to force the brush into the brush chipper. 
         [0029]    Once the brush has been chipped into wood chips, the resulting wood chips are expelled through a rotatable chute  130 . 
         [0030]    The brush chipper is often mounted on wheels  140  (only one shown in  FIGS. 1 and 2 ), as shown, however, tracks and skids may also be used, and the brush chipper  10  may be stationary as well. The present invention is not limited to any particular conveyance apparatus, nor does it require the brush chipper  10  be portable. 
         [0031]    Generally, the brush chipper  10  has an infeed end  150  and an outfeed end  160 . A feed direction is defined, for the purposes of this document, including the claims, as the direction the brush is forced while it is being chipped; that is, the feed direction is the direction going from the infeed end to the outfeed end of the brush chipper. 
         [0032]    As is clearly seen in  FIG. 3 , the feed table  110  is hingedly attached to the brush chipper  10  by a hinge  310 . The lower feed stop bar  100  comprises a control bar  320  extending substantially across the infeed end of the feed table  110 , and two pivot arms  330  by which the lower feed stop bar  100  is operatively, pivotally attached to flanges  340 , which, in turn, are operatively attached to the feed table  110 . 
         [0033]    The feed table  110  stows against the brush chipper  10  for transport as seen in  FIG. 8 . Folding the feed table  110  is effected by pivoting the feed table  110  on its hinge  310 .  FIG. 7  illustrates the feed table  110  in the position used for chipping brush. 
         [0034]    Detail views of the lower feed stop bar  100  are shown in  FIGS. 4-6 . The pivot arms  330  (only one visible) are operatively, pivotally attached at an axis of rotation  410  to the flanges  340  (only one visible). The pivot arms  330  are rigidly attached or integral with the control bar  320 . Hence, the lower feed stop bar  100  assembly, comprising the control bar  320  and the flanges  330 , rotates about the axis of rotation  410 . 
         [0035]    The control bar  320  engages a movable stop  420 , which, in turn, engages a spring  430 . Thus, the movable stop  420  can be forced into the spring and moved, yet still provides a force to maintain the lower feed stop bar in an untripped position as shown in  FIG. 4 . An adequate force in the infeed direction, that is, to the left in  FIG. 4 , will cause the feed stop bar  100  to rotate about its axis of rotation  410  against a force of the spring  430 . 
         [0036]    Preferably connected to or integral with the pivot arm  330  is a curved finger  510  made to engage a normally closed switch  440 , the switch providing a signal to keep the brush feed rollers turning. When the curved finger  510  engages the switch  440 , as shown in  FIGS. 5 and 6 , the switch contacts open, thus causing the brush rollers to cease turning. 
         [0037]    A link arm  450  is pivotally connected to the stop  420  at a first end. A second end, having a slot  460 , is pivotally, slidably engaged to a pivot  470 , as seen in  FIGS. 7 and 8 . When the feed table  110  is down in its operating position, as shown in  FIG. 7 , the stop  420  is allowed to move horizontally because the pivot  470  is free to slide in the slot  460 . In  FIG. 4 , the lower feed stop bar  100  is in operating position, and the pivot  470  is seen to be against the distal end of the slot  460  in the second end of the link arm  450 . 
         [0038]    In  FIG. 5 , the lower feed stop bar  100  has been pushed in the feed direction, that is, to the left in the orientation shown in  FIG. 5 . The finger  510  has just begun to engage the switch  440 . The pivot  470  is seen to be between the ends of the slot  460  at this position of the feed stop bar  100 . Although the spring  430  is not shown in  FIG. 5 , it is in a partially compressed condition when the feed stop bar  100  is in the position shown in  FIG. 5 . 
         [0039]    The lower feed stop bar  100  is shown in its most depressed position in  FIG. 6 . The proximal end of the slot  460  in the link arm  450  has reached the pivot  470  due to the extent by which the lower feed stop bar  100  has been forced in the feed direction, in other words, to the right in  FIG. 6 . 
         [0040]    An additional feature of the instant invention is shown in  FIG. 6  wherein the switch  440  may reside in a plurality of positions in the feed direction. In the preferred embodiment, the switch  440  may take two positions: a first position for normal sensitivity of the feed stop action, and a second position, displaced from the first position in the feed direction, wherein the sensitivity is reduced compared to the normal sensitivity of the first position. Clearly, when the switch is in the second position, shown in  FIG. 6 , the lower feed stop bar  100  must be rotated about the axis of rotation  410  to a greater extent than if the switch  440  is in the first position, as shown in  FIGS. 4 and 5 . 
         [0041]    An additional feature of the present invention is seen by comparing  FIGS. 7 and 8 . When the feed table  110  is in its lowered position as shown in FIGS.  1  and  3 - 7 , as explained above, the lower feed stop bar  100  is forced toward the infeed end  150  of the brush chipper  10  by the spring  430 . Sufficient travel toward the infeed end  150  is permitted by the slot  460  in the link arm  450  because the distance between the pivot  470  and the switch  440  is such that the lower feed bar  100  can extend away from the switch  440 . When the feed table  110  is in its raised position as shown in  FIGS. 2 and 8 , the distance between the pivot  470  and the switch  440  is greater than when the feed table  110  was in its lowered position. Hence, the link arm  450  is pulled toward the pivot  470  and sufficient force is applied to the spring  430  to engage the finger  510  to the switch  440 , thereby disallowing the feed mechanisms to operate as long as the feed table  110  is in its raised position. Preferably, the feed table  110  is in its raised position during transport of the brush chipper  10 . 
         [0042]    A flow chart of the logic of control with the lower feed stop bar  100  is shown in  FIG. 9  and is largely self explanatory. If the lower feed stop bar  100  is fully extended  910  in toward the infeed end of the brush chipper  10 , the switch  440  is closed  920  and brush feeding is permitted  930  if the operator desires. If, on the other hand, the lower feed stop bar  100  is pushed in the feed direction  940 , it must be pushed sufficiently far to engage the switch  440 . The required distance the lower feed stop bar  100  must be pushed is dictated by whether the switch  440  is located in the normal sensitivity position, or the reduced sensitivity position. If the switch is engaged and, thus, open  950 , the feed mechanisms in the brush chipper  10  are disallowed from feeding brush  960 . 
         [0043]    The above embodiment is the preferred embodiment, but this invention is not limited thereto. It is, therefore, apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.