Tension control system for round bale forming apparatus

Abstract: A round baler is disclosed for forming crop material into cylindrical bales. The baler has a main frame (11), a pair of side walls, a crop pick-up (16) mounted on the main frame, and a tailgate (14) pivotally connected to the main frame. The tailgate is operative between a closed position during which a bale is being formed in an expandable chamber, and an open position during which a formed bale is being discharged from the chamber. A sledge assembly (20), pivotally mounted on the main frame (11) for movement between a bale starting position and a full bale position, has crop engaging transverse rolls (21-23) for urging the crop material along a spiral path in the chamber for starting and forming a bale. An apron (32) is supported along a continuous path on the main frame (11) and tailgate (14) by a plurality of rotatable guide members (33-36, 38, 40). The path has an inner course (c) that cooperates with the sledge rolls (21-23) on the sledge assembly (20) to define the chamber. A take-up assembly (41, 43, 44), affixed to the sledge assembly, moves therewith between the bale starting position and full bale position. Structural twisting during uneven loading of the bale chamber is countered by a hydraulic cylinder (50) affixed between the main frame (11) and the sledge assembly (20).

Description: The present invention relates to agricultural apparatus for forming and wrapping cylindrical packages of crop material, generally referred to as round balers, and more particularly to a tension control system for a round baler in which a package of crop material is formed in an expandable, generally cylindrically shaped forming chamber. Round balers generally have a bale forming chamber defined by a pair of opposing side walls associated with an array of side-by-side belts, transverse slats trained on chains, a plurality of transverse rolls or a combination of these various elements, e.g., rolls and belts. During field operation, windrowed crop material such as hay is picked up from the ground and fed in a continuous stream into a fixed or variable diameter chamber. The hay is rolled into a cylindrical package within the chamber, wrapped with twine, net or the like and ejected onto the ground for subsequent handling. US-A-5,444,969 discloses a prior art round baler of the general nature described above. In this particular type of baler an expandable chamber is defined by a pair of sidewalls, and a plurality of side-by-side belts cooperating with a series of transverse rolls, mounted between a pair of pivotally mounted arms. The chamber includes an inlet opening in the front through which crop material is fed. The aforementioned arrangement of rolls and arms is commonly referred to as a sledge assembly. Also shown in the disclosed baler is a pair of take-up arms pivotally mounted on the main frame, between which arms a pair of guide rolls are journalled. The outer surfaces of the guide rolls are urged against the belts to maintain belt tension and thereby prevent slack from occurring in the belts during expansion and contraction of the chamber. General arrangements of this nature are commonly referred to as apron tensioning systems. Examples of prior art tensioning systems used in round balers of the general type shown in US-A-5,444,969, are disclosed in US-A-5,014,613, US-A-5,327,821 and US-A-5,367,865. In US-A-5,014,613 the apron tensioning system shown employs a spring and pivot arm combination, while in US-A-5,327,821 a system is shown that utilizes an hydraulic cylinder in combination with a pivot arm assembly. The tensioning mechanism in US-A-5,014,613 discloses a prior art system in which both a spring and an hydraulic cylinder are used. In the three aforementioned apron tensioning systems, the elements are all mounted outwardly of the sidewalls of the balers Another type of round baler is shown in US-A-4,698,955. Herein crop material is compressed in a variable chamber defined by a set of stationary rollers around the periphery of the finished bale and a movable sledge assembly which comprises a pair of pivot arms with a series of rollers. A hydraulic cylinder can move the sledge assembly between a front position for creating a small baling start chamber and a rear position in which the sledge extends along the periphery of the finished bale. There is no interaction between the movable and the stationary rollers. The present invention relates to apron tensioning for a round baler in which a cylindrical package of crop material is formed between expandable walls consisting of a combination of belts and rolls of the general nature described in US-A-5,444,969, cited above. This patent is an example of many prior art patents, assigned to New Holland North America, Inc., that disclose this type of round baler, referred to by some as a roll/belt round baler. It is an object of the present invention to provide structural characteristics for a roll/belt round baler, which among other things, enhance performance, simplify construction and improves durability. More specifically, means are sought for preventing structural twisting during expansion of the chamber. According to the invention, there is provided a round baler for forming crop material into cylindrical bales, said baler comprising: a main frame; a tailgate pivotally connected to said main frame, said tailgate being operative between a closed position during which a bale is being formed, and an open position during which a formed bale is being discharged; a sledge assembly mounted on said main frame for movement between a bale starting position and a full bale position, said sledge assembly including conveying means having a crop engaging surface extending transversely of said main frame; an apron supported along a continuous path on said main frame and on said tailgate, said apron path having an inner course that cooperates with said conveying means of said sledge assembly to define a bale forming chamber; a take-up assembly movable between a bale starting position and a full bale position for taking up the slack of said apron during bale formation; and a pick-up for feeding crop material into said chamber; characterized in that: said take-up assembly includes take-up means affixed to said sledge assembly for movement therewith between said bale starting position and said full bale position; and said baler further comprises: a hydraulic cylinder and means for mounting said hydraulic cylinder between said main frame and said sledge assembly for providing a compressive load on said sledge assembly, under conditions where said sledge assembly is moving between said starting position and said full position. In this manner the movement of the sledge is controlled in a more rigid manner. This is of particular importance during the first stage of the bale formation, when the apron is not fully tensioned yet. There is a noted improvement in the appearance and density of round bales formed by such baler. Most advantageously, the hydraulic cylinder is mounted by coupling means to the transverse center section of said the assembly. In this manner the load exerted by the cylinder is distributed evenly over both halves of the bale. The movement of the idler roll on top of the sledge assembly is more rigidly controlled, such that the tendency for structural twisting of the apron belts is reduced even further. The hydraulic cylinder may be part of circuit means further comprising pressure relief means set to relieve the cylinder pressure when a predetermined force is applied against the sledge. These relief means may include an adjustable relief valve. In this manner an adjustable tensioning system is provided for varying the density of bales formed in the chamber. A baler in accordance with the present invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevational view of a round baler in which the present invention is incorporated; the tailgate is in the closed position and the elements of the bale forming chamber are shown in their core starting condition; Figure 2, generally similar to Figure 1, is a diagrammatic side elevational view of a round baler in which the tailgate is in the closed position and the elements of the bale forming chamber are shown in an intermediate bale forming condition; Figure 3, also generally similar to Figure 1, is a diagrammatic side elevational view of a round baler in which the tailgate is in the closed position and the elements of the bale forming chamber are shown in the full bale condition; Figure 4, also a diagrammatic side elevational view of a round baler, shows the tailgate in the open position and the relationship of the elements of the bale forming chamber after a bale has been discharged; Figure 5 is a top view taken along lines 5-5 in Figure 2; and Figure 6 is a schematic diagram of a hydraulic circuit used in the preferred embodiment of the present invention. The terms "front" and "rear" used throughout this description are defined with reference to the normal direction of travel of the baler during baling operations. However they are not to be construed as limiting terms. Figure 1 shows the cross section of a round baler 10 of the type in which the present invention is readily embodied. Baler 10 has an expandable chamber defined in part by belts and rolls. This type of expandable chamber is disclosed in various prior art patents, e.g., US-A-5,444,969 mentioned above, and US-A-4,870,812, both of which are hereby incorporated by reference. It should be noted that throughout this description the drawings are diagrammatic in nature to best show the elements of the baler in which the invention is embodied. To this end, in many instances only one element in a pair is shown, especially in those cases where identical elements exist, disposed on opposing sides of the baler, e.g., wheels. Baler 10 has a main frame 11, comprising a plurality of rigid structural elements including a pair of side walls 19 (only one shown). Main frame 11 is supported by a pair of wheels 12 (also only one shown). A forwardly mounted tongue 13, integral with main frame 11, provides for connection to a tractor. Pivotally connected to side walls 19 by a pair of stub shafts 15 (only one shown) is a tailgate 14 which is closed during bale formation. Tailgate 14 includes walls 19' coplanar with side walls 19. A pick-up 16, mounted on main frame 11, has a plurality of tines 17, the tips of which are movable along a predetermined path to lift crop material from the ground and deliver it rearwardly along a generally horizontal path toward a floor roll 18, rotatably mounted on main frame 11. An expandable chamber for forming bales is defined by side walls 19, 19', belts and a sledge assembly 20, operative between the inwardly facing surfaces of such walls. Sledge assembly 20 comprises a plurality of transversely extending rolls 21, 22, 23 journalled at their ends in a pair of spaced apart arms 24, one of which is shown. These arms are pivotally mounted on stub shafts 26 for providing movement of sledge assembly 20 from the bale starting position shown in Figure 1 through the partly full position shown in Figure 2 to the full bale position shown in Figure 3, and finally to the bale discharge position shown in Figure 4. Rolls 21, 22, 23 are driven in a counter-clockwise direction by conventional means (for example, chains and sprockets) coupled via an appropriate drive train to a drive shaft 28. A starter roll 30, located adjacent roll 23, is also driven counter-clockwise. Sledge assembly 20 includes a fourth roll, a freely rotatable idler roll 31, also carried between arms 24. A cylinder 50, mounted between cross beam 29 of main frame 11 and sledge assembly 20, provides a compressive force that resists the force on sledge 20 under conditions where the chamber is expanding. The function of cylinder 50 will be discussed in further detail below. The bale forming chamber is further defined by an apron 32 comprising a plurality of laterally spaced side-by-side belts supported by guide rolls 33, 34, 35, rotatably mounted in tailgate 14, and roll 36, rotatably mounted on stationary arms 37, affixed to main frame 11. Apron 32 is also supported on a drive roll 38, mounted on main frame 11. Although apron 32 passes between roll 21 and idler roll 31, it is in engagement only with idler roll 31 and not roll 21. In addition to its bale forming function, roll 21 also serves to strip crop material from the belts. Suitable coupling means (not shown) connected to drive shaft 28 provide rotation of drive roll 38 causing movement of apron 32 along its varying paths in the directions indicated by the arrows in FIGS. 1, 2 and 3. An additional guide roll 40 in the main frame 11 ensures proper driving engagement between the surfaces of the belts of apron 32 and the surface of drive roll 38. A pair of take-up arms 41 (only one shown), integral with sledge assembly 20, are affixed to sledge arms 24 for movement between inner, intermediate, outer and bale discharge positions shown in Figures 1, 2, 3 and 4, respectively. Take-up arms 41, which carry additional guide rolls 43, 44 for supporting apron 32, are urged with sledge assembly 20 toward the innermost position (Figure 1), i.e., bale starting position, by tensioning spring 42, mounted between one of arms 41 and main frame 11 by bracket assembly 39, affixed to main frame 11. Spring 42, mounted outwardly from wall 19, is pivotally secured to arm 41 by journal means 53 extending through access slot s in side wall 19. While a basic function of spring 42 is to return the sledge and take-up assemblies to the start position after a bale is discharged, it also provides a force on sledge assembly 20 that resists expansive forces on the elements defining the chamber, under conditions where a cylindrical package of crop material is progressively expanding during formation. When the elements of round baler 10 are disposed as shown in Figure 1, an inner course c of apron 32 extends between guide roll 35 and idler roll 31 to form the rear wall of the core starting chamber while the inwardly facing peripheral surfaces of rolls 21, 22, 23 define in a general manner a rearwardly inclined cooperating front wall. Floor roll 18 defines the bottom of the chamber and, with starter roller 30, provides an inlet for crop material. When round baler 10 travels across a field, pick-up tines 17 lift crop material from the ground and deliver it through the inlet. The crop material is carried rearwardly by floor roll 18 into engagement with apron inner course c (Figure 1) which urges it upwardly and forwardly into engagement with the rolls on sledge 20. In this manner crop material is coiled in a clockwise direction to start a bale core. Continued feeding by pick-up tines 17 of crop material into the bale forming chamber in a generally spiral fashion causes the apron inner course c to expand in length around a portion of the circumference of the cylindrical package of crop material as its diameter increases (Figure 2). Take-up arms 41 rotate with sledge assembly 20 about the coaxial horizontal axes of stub shafts 26 from their initial positions shown in Figure 1 toward their outer positions shown in Figure 3 to provide for expansion of the inner course of the apron in a manner similar to that of the prior art balers mentioned above, i.e., in effect the outer course of the belts of apron 32 is diminished in length while the inner course c increases a like amount. After a cylindrical package of crop material has been formed in the fashion described above and wrapped with twine or net in a well known manner to form a bale, tailgate 14 is opened and the bale is ejected rearwardly as shown in Figure 4. Subsequent closing of tailgate 14 returns the inner and outer courses of the belts of apron 32 to the locations shown in Figure 1. During bale formation, sledge assembly 20, along with the above described integral take-up assembly, moves between a bale starting position (Figure 1) to a full bale position (Figure 3). This movement of sledge assembly 20 causes idler roll 31 to move along a generally arcuate path while maintaining apron 32 in close proximity to roll 21, thereby allowing roll 21 to strip crop material from the belts and prevent or reduce significantly the loss of crop material through the space between roll 21 and apron 32 during formation of a bale. Sledge assembly 20 is pushed outwardly towards its full bale position during bale formation as the crop material expands against rolls 21, 22, 23 and then subsequently is returned inwardly by apron 32 and spring 42 to the position shown in Figure 1. With the above description and general operation of baler 10 as a background, attention will now be directed to important features of the tensioning system to which the present invention is directed. As will become apparent, baler 10 is merely illustrative of one of the many round baler configurations to which such features are adaptable. For example, varying the number of rolls on the sledge assembly or altering the pivot location of the sledge assembly would have no affect on the general aspects of the present invention. It is also conceivable to replace the set of rolls with other crop conveying means such as a second apron. To further enhance understanding of the present invention, attention is directed to the apron tensioning system shown in Figures 5 and 6. Hydraulic cylinder 50, generally referred to in the above description of Figures 1-4, is mounted in a fore-and-aft direction between cross beam 29 of main frame 11 and cross element 51 affixed between arms 24 (Figures 1-4) of sledge assembly 20, on which rollers 21, 22 and 23 are rotatably mounted. Cylinder 50 is pivotally mounted on beam 29 by conventional mounting assembly 45. Operative in conjunction with cylinder 50 is conventional tensioning spring 42, referred to above. Spring 42 is pivotally attached via transverse journal 53 to the forward end of integral take-up arm 41. Spring 42 is attached at its other end to the main frame 19 by bracket assembly 39. The rod end of hydraulic cylinder 50 is coupled to cross element 51 of sledge assembly 20 in the general transverse center thereof by pivotal mounting means 54 in which the distal end of reciprocal rod 55 is attached via a collar pivotally mounted on a transverse pin extending between a pair of mounting tabs 57. A hydraulic circuit comprising cylinder 50, a pressure relief valve 56 (Figure 6), on/off ball valve 58, reservoir 59, and one-way check valve 60, are operative to maintain a predetermined load on the center of the sledge and take-up assembly during expansion of the chamber during bale formation. Pressure relief valve 56, adjustable in a conventional manner, is set to relieve the pressure in cylinder 50 and permit fluid to flow therethrough when a predetermined force is applied against sledge assembly 20, during expansion of the chamber as a cylindrical package of crop material is being formed. By adjusting the setting of valve 56 the density of the bale being formed can be controlled. One-way check valve 60 is operative to replenish fluid to the cylinder when the sledge assembly returns to its initial position causing rod 55 to move outwardly, i.e., from right to left in Figure 6. Under conditions where a windrow of crop material is being picked up from the ground and fed into the chamber, resulting in a continuously expanding cylindrical package of crop material, a predetermined compressive force can be maintained on the sledge. This force is centralized by virtue of the location of cylinder 50, and thereby prevents structural twisting of take-up arms 41, which are integral with the sledge assembly 20. Thus, during operation, the uneven load exerted by crop material expanding against the sledge rolls and the apron belts, the path of which is trained about idler roll 31 mounted on the sledge, is neutralized by centrally located cylinder 50. This obviates various problems, not the least of which is the tendency for the belts to track in an unsuitable manner when the belt supporting rolls are skewed due to uneven forces. Testing has also determined that this arrangement permits increased bale density over levels heretofore attained.

Claims: A round baler (10) for forming crop material into cylindrical bales, said baler comprising: a main frame (11); a tailgate (14) pivotally connected to said main frame (11), said tailgate (14) being operative between a closed position during which a bale is being formed, and an open position during which a formed bale is being discharged; a sledge assembly (20) mounted on said main frame (11) for movement between a bale starting position and a full bale position, said sledge assembly (20) including conveying means (21-23) having a crop engaging surface extending transversely of said main frame (11); an apron (32) supported along a continuous path on said main frame (11) and on said tailgate (14), said apron path having an inner course (c) that cooperates with said conveying means (21-23) of said sledge assembly (20) to define a bale forming chamber; a take-up assembly (41-44) movable between a bale starting position and a full bale position for taking up the slack of said apron (32) during bale formation; and a pick-up (16) for feeding crop material into said chamber; characterized in that : said take-up assembly (41-44) includes take-up means (41, 43, 44) affixed to said sledge assembly (20) for movement therewith between said bale starting position and said full bale position; and said baler further comprises: a hydraulic cylinder (50) and means (45, 51, 54, 57) for mounting said hydraulic cylinder (50) between said main frame (11) and said sledge assembly (20) for providing a compressive load on said sledge assembly (20), under conditions where said sledge assembly is moving between said starting position and said full position. A round baler according to claim 1, characterized in that said mounting means (45, 51, 54, 57) comprise means (51, 54, 57) for coupling said hydraulic cylinder (50) to the transverse center section of said sledge assembly (20). A round baler according to claim 2, characterized in that said coupling means (51, 54, 57) comprise: a rigid transverse element (51) affixed to said sledge assembly (20) for movement in concert therewith; and pivotal attachment means (54) located in the general transverse center of said transverse element (51) for securing said cylinder (50) thereto. A round baler according to any of the preceding claims, characterized in that : said apron (32) comprises a plurality of side-by-side belts; and said baler further comprises drive means (28, 38) for moving said apron (32) along said continuous path, said drive means (28, 38) comprising a driven roll (38) having an outer generally cylindrical surface in frictional engagement with said belts under conditions where said tailgate (14) is closed. A round baler according to any of the preceding claims, characterized in that said conveying means (21-23) of said sledge assembly (20) comprise at least two driven rolls, the outer surfaces of which engage said crop material under conditions where said pick-up (16) feeds crop material into said chamber, said rolls (21-23) being driven in a direction that urges said crop material along a spiral path in said chamber. A round baler according to claim 5, characterized in that one of said at least two driven rolls (21-23) is pivotally mounted on said main frame (11). A round baler according to any of the preceding claims, characterized in that it further comprises resilient means (42) for urging said sledge assembly (20) to said bale starting position. A round baler according to claim 7, characterized in that said resilient means (42) is affixed at one end to said sledge assembly (20) and affixed at the other end to said main frame (11), whereby said resilient means (42) provides a force that urges said sledge assembly (20) to pivot about said at least one of said two driven rolls (21-23). A round baler according to claim 8, characterized in that said force urges said sledge assembly (20) in a direction that reduces the compression load on said hydraulic cylinder (50). A round baler according to any of the preceding claims, characterized in that it further comprises hydraulic circuit means (50, 56, 58-60) comprising said cylinder (50) and pressure relief means (56) set to relieve the pressure in said cylinder (50) when a predetermined force is applied against said sledge assembly (20) under conditions where crop material is being fed into said chamber. A round baler according to claim 10, characterized in that said pressure relief means comprise a pressure relief valve (56) which is adapted to vary said predetermined force.

Inventors: UNDERHILL KENNETH, WHITE DENNIS L, UNDERHILL, KENNETH, WHITE, DENNIS L.
Applicants: CNH BELGIUM NV, CNH BELGIUM N.V.
Application year: 1999
Main classification: A01F15
IPC codes: A01F15