Abstract:
A large square baler is equipped with a plunger drive incorporating a flywheel configured as a fan which creates a flow of air within a housing disposed about the flywheel. A duct arrangement is coupled between the housing and a knotter table housing so that air is directed across and maintains a plurality of knotters located at the knotter table free of debris.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the removal of debris from the knotter table of large square balers, and more particularly relates to an onboard fan or blower for creating air flow for such removal of debris. 
     BACKGROUND OF THE INVENTION 
     All large square balers on the market today have a dedicated source supplying pressurized air to the knotter table for the purpose of keeping it free from the buildup of debris including hay and straw residue. The buildup of debris on the knotter table causes missed ties, which contributes to poor reliability of the tying function. U.S. Pat. No. 7,318,376 discloses a cross flow blower for blowing air across the knotter table. This blower is driven by a hydraulic motor. Another known baler uses a plurality of electrically driven axial flow fans for either blowing or vacuuming debris from the knotter table. 
     It is desired then to provide other than a dedicated source for air for the purpose of knotter table cleaning. 
     SUMMARY OF THE INVENTION 
     According to the present invention, a large square baler is equipped with a novel device for supplying pressurized air for cleaning the knotter table of debris such as crop residues. 
     An object of the invention is to incorporate a fan or blower structure in a baler component having another use. 
     The above object is accomplished by forming a baler drive flywheel as a fan or blower for generating air flow that is routed for cleaning the knotter table. Respective embodiments are provided wherein the flywheel is configured with back curved impeller elements, with forward curved impeller elements or with blades shaped for creating an axial air flow. 
     The foregoing and other objects will be apparent upon reading the ensuing description together with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic left side view of a large square baler having a drive arrangement incorporating a housed flywheel configured as a centrifugal fan for supplying air for cleaning the knotter table. 
         FIG. 2  is an enlarged left side view of the housed flywheel shown in  FIG. 1 , with a portion of the housing broken away revealing the flywheel, which includes backward curved fins. 
         FIG. 3  is a rear view of the housed flywheel shown in  FIG. 2 , but with a rear section of the housing being removed exposing the backward curved fins. 
         FIG. 4  is a top view of an air delivery manifold defining a rear end portion of the air delivery duct shown in  FIG. 1  and shown directing air toward the knotters forming a portion of the knotter table. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , there is shown a typical large square baler  10  including a main frame  12  supported on ground wheels  14  and to a forward end of which a tongue  16  is joined, with the tongue being adapted for attachment to a towing vehicle (not shown) such as an agricultural tractor. An elongate, fore-and-aft extending baling chamber  18  is carried by the frame  12  and is provided with a bottom opening, not shown, to which a pre-compression chamber, in the form of a chute  20  which curves upwardly and rearwardly from a forward end located for receiving crop delivered to it by the action of a crop pick-up  22  and a packer fork arrangement  24 , with a stuffer fork arrangement  26  being provided for sweeping a charge of pre-compressed crop material from the chute  20  into the baling chamber  18 . A plunger  26  is mounted for reciprocating within a forward end region of the baling chamber  18 . 
     The plunger  28  is driven from a drive arrangement including a drive shaft  30  having a forward end coupled to a power take-off shaft (not shown) of the towing tractor. The drive shaft  30  has a rear end coupled to a shaft  32  to which a flywheel  34  (see  FIGS. 2 and 3 ) is fixed for rotation and which has a rear end coupled to an input shaft (not shown) of a transmission located within a gear housing  36 , the transmission having an output shaft  38  having opposite end regions projecting outwardly of the housing and having crank arms  40  fixed thereto, with only the left crank arm being shown. Connected between an end of each crank arm  40  and the plunger  28  is a connecting rod  42 . Thus, as the output shaft  38  rotates, the rotating motion of the crank arms  40  is transferred by the connecting rods  42  to the plunger  28  so as to cause the plunger to reciprocate and compress charges of crop material received from the chute  20  into the baling chamber  18  so as to form a bale. When the forming bale reaches a preselected length, a bale measuring device (not shown) causes a twine delivery needle drive arrangement  44  to be actuated so as to move a needle yoke  46  including a plurality of transversely spaced needles  48  to swing through the baling chamber and deliver twine to respective knotters  50  (see  FIG. 4 ) of a knotter table located within a housing  52 , the knotters acting to tie knots in lengths of twine extending about the formed bale. The number of knotters varies according to the size of the bales, with five knotters  50  being disclosed. 
     The flywheel  34  has a primary function of evening out the flow of power driving the plunger  28 , but in addition is designed as a centrifugal blower fan comprising a circular plate  54  having backward curved fins  56  arranged in a circular array on one side of the plate  54 . The flywheel  34  is contained within a scroll-shaped, volute housing  58  provided with an inlet  60  encircling the drive shaft  30  to which the flywheel  34  is fixed. The housing  58  defines an outlet  62  disposed tangentially to the flywheel  34  and being coupled to a duct arrangement  64  that extends rearward to a location at the forward side of the knotter table housing  52 , the rear of the duct arrangement being defined by a manifold  66  extending transversely in front of the housing  44  and having transversely spaced nozzles  68  coupled thereto and projecting into the housing  44  in alignment with the transversely spaced knotters  50  contained within the housing. 
     Thus, it will be appreciated that whenever the flywheel  34  is being driven from the towing tractor power take-off, air will be delivered to the housing  52  so as to blow debris away from the knotters  50  located within the housing and in that way prevent misties which might otherwise happen due to the build-up of debris on the knotters. 
     While the flywheel  34  is configured as a centrifugal fan having backward curved fins  56  fixed to one side of the plate  54  it is to be understood than any fan configuration would be suitable. For example, the fins  56  could be replaced with forward curved fins, and fins could be fixed to both sides of the plate  54 , with an additional air inlet being provided in the volute housing for that side. As a further alternative, the housing could be divided into two separate sections, each having its own inlet and outlet, with the two outlets being coupled to separate ducts that lead back to the knotter table. Also, it is possible to construct the flywheel so as to define an axial flow fan, with duct work being provided for routing this flow to the knotter table. 
     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.