Abstract:
An agricultural baler comprising a main bale chamber having a pair of opposed side walls. Each side wall includes a plunger slot arrangement defining a plunger slot. Each plunger slot has opposite ends and is open at both an inside adjacent to a plunger and an opposite outside. The plunger is reciprocally disposed within the main bale chamber, and includes a pair of opposed sides and at least one roller extending laterally outward from each side. Each roller is positioned within a respective plunger slot. The baler is characterized by a pair of plunger slot covers, with each cover only partially covering a respective outside of a corresponding plunger slot such that each end of the plunger slot is uncovered.

Description:
BACKGROUND OF THE INVENTION 
     This application claims foreign priority under 35 U.S.C. §119 to Belgian Application BE2014/0052 filed Jan. 30, 2014 titled “Agricultural Baler with a Plunger Slot Cover” and having Wouter Boone as the inventor. The full disclosure of BE2014/0052 is hereby incorporated herein by reference. 
     1. Field of the Invention 
     The present invention relates to agricultural balers, and, more particularly, to bale chambers within such balers. 
     2. Description of the Related Art 
     Agricultural harvesting machines, such as balers, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales. 
     On a large square baler, a pickup unit at the front of the baler gathers the cut and windrowed crop material from the ground. The pickup unit includes a pickup roll, and optionally may include other components such as side shields, stub augers, wind guard, etc. 
     A packer unit is used to move the crop material from the pickup unit to a duct or pre-compression chamber. The packer unit forms a wad of crop within the pre-compression chamber which is then transferred to a main bale chamber. (For purposes of discussion, the charge of crop material within the pre-compression chamber will be termed a “wad”, and the charge of crop material after being compressed within the main bale chamber will be termed a “flake”). Typically such a packer unit includes packer tines or forks to move the crop material from the pickup unit into the pre-compression chamber. Instead of a packer unit it is also known to use a rotor cutter unit which chops the crop material into smaller pieces. 
     A stuffer unit transfers the wad of crop material in charges from the pre-compression chamber to the main bale chamber. Typically such a stuffer unit includes stuffer forks which are used to move the wad of crop material from the pre-compression chamber to the main bale chamber, in sequence with the reciprocating action of a plunger within the main bale chamber. 
     In the main bale chamber, the plunger compresses the wad of crop material into flakes to form a bale and, at the same time, gradually advances the bale toward the outlet of the bale chamber. The plunger reciprocates, back and forth, toward and away from the discharge end of the baler. The plunger may include a number of rollers which extend laterally outward from the sides of the plunger. The rollers on each side of the plunger are received within a respective plunger slot formed in the side walls of the bale chamber, with the plunger slots guiding the plunger during the reciprocating movements. 
     When enough flakes have been added and the bale reaches a full (or other predetermined) size, a number of knotters are actuated which wrap and tie twine, cord or the like around the bale while it is still in the main bale chamber. The twine is cut and the formed baled is ejected out the back of the baler as a new bale is formed. 
     During the bale formation within the bale chamber, as described above, crop material can be forced through the plunger slots on opposite sides of the bale chamber. The crop material can accumulate outside of the bale chamber, such as in an area around the axle, or in an area between the twine box and the frame. It is thus necessary for the operator to periodically dismount from the traction unit and clean the crop from the baler. This takes time and effort on the part of the operator, reducing the baling efficiency of the baler. 
     German patent document DD 288 309 B5 discloses a baler with a plunger slot arrangement having a panel that carries an upper guide rail and lower guide rail. Plunger rollers run between the guide rails. The panel provides the structural framework for the plunger slot arrangement, and appears to be formed as an extrusion which is closed on the side opposite from the plunger. Since the panel provides the structural support for the plunger slot arrangement, and also appears to be formed as an extrusion, the outside closed wall apparently extends the full length of the plunger slot arrangement. Crop material would tend to accumulate within the plunger slot, which in turn could negatively affect the reciprocating movement of the plunger rollers within the plunger slot. 
     What is needed in the art is an agricultural baler which avoids problems of crop accumulation in areas outside of the bale chamber. 
     SUMMARY OF THE INVENTION 
     The present invention provides an agricultural baler with a plunger slot cover which partially covers an outside of a corresponding plunger slot, with each end of the plunger slot remaining uncovered. 
     The invention in one form is directed to an agricultural baler, including a main bale chamber having a pair of opposed side walls. Each side wall includes a plunger slot arrangement defining a plunger slot. Each plunger slot has opposite ends and is open at both an inside adjacent to a plunger and an opposite outside. The plunger is reciprocally disposed within the main bale chamber, and includes a pair of opposed sides and at least one roller extending laterally outward from each side. Each roller is positioned within a respective plunger slot. The baler is characterized by a pair of plunger slot covers, with each cover partially covering a respective outside of a corresponding plunger slot such that each end of the plunger slot is uncovered. 
     An advantage of the present invention is that crop material is inhibited from passing through the plunger slot and accumulating on the baler in an area outside of the main bale chamber. 
     Another advantage is that each cover only partially covers a corresponding plunger slot so that the plunger slot remains substantially free of crop material. 
     Yet another advantage is that by leaving both ends of the plunger slot uncovered, the rollers move air back and forth through the plunger slot and out the uncovered ends to keep the plunger slot substantially free of crop material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective cutaway view showing the internal workings of a large square baler, which may include a main bale chamber with a plunger slot arrangement and plunger slot cover of the present invention; 
         FIG. 2  is a fragmentary, partially exploded, perspective view of the main bale chamber shown in  FIG. 1 , including side walls defining a plunger slot arrangement and an embodiment of a plunger slot cover of the present invention; 
         FIG. 3  is a side view of the main bale chamber shown in  FIG. 2 , with the plunger slot cover installed; 
         FIG. 4  is a sectional view of the plunger slot arrangement shown in  FIGS. 2 and 3 , taken along line  4 - 4  in  FIG. 3 , with an optional scraper attached to the roller assembly; and 
         FIG. 5  is a top view of the roller assembly shown in  FIG. 4 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a perspective cutaway view showing the internal workings of a large square baler  10 . Baler  10  operates on a two stage feeding system. Crop material is lifted from windrows into the baler  10  using a pickup unit  12 . The pickup unit  12  includes a rotating pickup roll  14  with tines  16  which move the crop rearward toward a packer unit  18 . An optional pair of stub augers (one of which is shown, but not numbered) are positioned above the pickup roll  14  to move the crop material laterally inward. The packer unit  18  includes packer tines  20  which push the crop into a pre-compression chamber  22  to form a wad of crop material. The packer tines  20  intertwine the crop together and pack the crop within the pre-compression chamber  22 . Pre-compression chamber  22  and packer tines  20  function as the first stage for crop compression. Once the pressure in the pre-compression chamber  22  reaches a predetermined sensed value, a stuffer unit  24  moves the wad of crop from the pre-compression chamber  22  to a main bale chamber  26 . The stuffer unit  24  includes stuffer forks  28  which thrust the wad of crop directly in front of a plunger  30 , which reciprocates within the main bale chamber  26  and compresses the wad of crop into a flake. Stuffer forks  28  return to their original stationary state after the wad of material has been moved into the main bale chamber  26 . Plunger  30  compresses the wads of crop into flakes to form a bale and, at the same time, gradually advances the bale toward outlet  32  of main bale chamber  26 . Main bale chamber  26  and plunger  30  function as the second stage for crop compression. When enough flakes have been added and the bale reaches a full (or other predetermined) size, knotters  34  are actuated which wrap and tie twine around the bale while it is still in the main bale chamber  26 . Needles  36  bring the lower twine up to the knotters  34  and the tying process then takes place. The twine is cut and the formed bale is ejected from a discharge chute  38  as a new bale is formed. 
     Referring now to  FIGS. 1 and 2 , conjunctively, the main bale chamber  26  includes a pair of side walls  40 , with each side wall  40  having a plunger slot  42  therein. Each plunger slot  42  has a longitudinal extension in the directions of reciprocating movement of the plunger  30 , and supports the plunger  30  during the plunger strokes within the main bale chamber  26 . Each plunger slot  42  is sized and configured to received one or more rollers  44  which extend laterally from each side  46  of the plunger  30 . In the embodiment shown, a pair of substantially parallel rails  48  are attached to the side walls  40  and define the plunger slot  42 . The plunger  30  is shown with first and second rollers, designated  44 A and  44 B, which travel within a corresponding plunger slot  42 ; however, the number of rollers  44  extending from each side  46  can vary. Further, the plunger  30  can have an additional roller  50  extending from each side  46  which rotates about a vertical axis and engages a lower rail  48  to limit side to side movement of the plunger  30  during compression strokes. 
     According to an aspect of the present invention, and referring now to  FIGS. 2 and 3 , each plunger slot  42  is partially covered with a cover  52  in a manner which inhibits crop from exiting the plunger slot  42 , while at the same time inhibiting buildup of crop within the plunger slot  42 . Cover  52  is shown attached in  FIG. 3 , and is shown detached in  FIG. 2  with dashed lines to indicate the approximate attachment location. It will be appreciated that since the rollers  44  reciprocate back and forth within the plunger slot  42 , it is necessary to locate the cover  52  on the outside of the plunger slot  42  (on the side opposite from the plunger  30 ). If the plunger slot  42  is entirely covered, then crop can build up within the plunger slot and inhibit the reciprocating movement of rollers  44  during compression strokes of plunger  30 . To inhibit crop from exiting the plunger slot  42 , and also inhibit crop buildup within the plunger slot  42 , the cover  52  only partially covers a respective plunger slot  42  such that each end of the plunger slot  42  is uncovered. 
     More particularly, plunger slot  42  includes an upstream end  54 A and a downstream end  54 B, relative to a direction of bale movement within the main bale chamber  26 , indicated by directional arrow  56 . The plunger  30  reciprocates back and forth between a forward-most position (which is closest to the outlet  32 ), and an opposite rearward-most position. The first roller  44 A is closest to the upstream end  54 A and when the plunger  30  is at the rearward-most position, the portion of the plunger slot which is laterally adjacent to the first roller  44 A (shown in dashed lines in  FIG. 3 , with the left position of roller  44 A being hidden and the right position being an alternate position) is not covered with the cover  52 . In this manner, a small amount of crop is allowed to exit the plunger slot  42  at the open upstream end  54 A to inhibit buildup of crop material within the plunger slot  42 . Likewise, the second roller  44 B is closest to the downstream end  54 B and when the plunger  30  is at the forward-most position, the portion of the plunger slot which is laterally adjacent to the second roller  44 B is not covered with the cover  52 . In this manner, a small amount of crop is allowed to exit the plunger slot  42  at the open downstream end  54 B to inhibit buildup of crop material within the plunger slot  42 . 
     One way of establishing the amount of the plunger slot  42  which is to remain uncovered at both the upstream end  54 A and the downstream end  54 B is by only covering a predetermined portion of a length (L) of the plunger slot  42 . Referring to  FIG. 3 , the uncovered upstream end  54 A and uncovered downstream end  54 B are each shown as having a common uncovered length (X). The relationship between the uncovered length X and the overall length L can be expressed as X/L. For example, in one embodiment it is possible for the cover  52  to not cover approximately ¼ of the length L at the respective upstream end  54 A and downstream end  54 B. Of course, this ratio can vary from one baler to another and/or the ratio at each uncovered end can also vary relative to each other. Other methods of determining the amount of the plunger slot to remain open at each longitudinal end are also possible (e.g., using specific dimensions, or based on empirical data from testing, etc). 
     Referring to  FIGS. 4 and 5 , each roller  44  can be provided with an optional scraper  58  which further assists with inhibiting a buildup of crop material within plunger slot  42 . In the illustrated embodiment, scraper  58  is in the form of a generally W-shaped bracket (when viewed from the top in  FIG. 5 ) which is mounted on the laterally outer side of roller  44 A for movement with the roller  44 A. Scraper  58  can include an opening  62  through which a bolt  60  passes which mounts the roller  44 A to the lateral side  46  of plunger  30 . In the illustrated embodiment, the opening  62  is configured as a slot allowing vertical adjustment of the scraper  58  within the plunger slot  42 ; however, the opening  62  can also be configured as a simple through hole. A bushing or the like (not specifically shown) can be used around the bolt  60  to provide a slight clearance or standoff distance between scraper  58  and the laterally outer side of roller  44 A. For example, the bushing can extend between an inner race of the roller  44 A and the laterally inner side of scraper  58 . The scraper  58  can be positioned at a desired vertical location within the plunger slot  42 , and then the bolt  60  is tightened. Preferably, the scraper  58  is positioned more closely adjacent to the bottom rail  48  rather than the top rail  48  of the plunger slot  42 . The scraper  58  shown in  FIGS. 4 and 5  is just one example of a scraper which effectively removes crop material as the rollers  44  move back and forth within plunger slot  42 , and it will be appreciated that other configurations for the scraper are also possible. 
     In the embodiment illustrated in the drawings, cover  52  is formed from a metal plate. However, cover  52  can be formed from a different type of suitable material such as plastic, rubber, etc. 
     During operation of baler  10 , plunger  30  reciprocates back and forth during compression strokes within the main bale chamber  26 . As the plunger  30  reciprocates back and forth, the rollers  44  likewise reciprocate back and forth within a respective plunger slot  42 . The movement of the rollers  44  causes a movement of air within the plunger slot  42  which acts to blow out or remove the crop material from the plunger slot  42 . The optional scraper  58  also mechanically removes crop from within plunger slot  42 , and further causes air movement within the plunger slot  42  for removal of the crop material. The cover  52  only partially covers a respective plunger slot  42  such that each end of the plunger slot  42  is uncovered, and thereby inhibits crop from exiting the plunger slot  42 , and also inhibits crop buildup within the plunger slot  42 . 
     While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.