Abstract:
An implement drive arrangement for a wheel axle assembly pivotally connected to a housing. A drive element is supported on the axle for rotation with the wheel generally about the wheel axis. The housing rotatably supports a driven element for rotation about an axis generally fixed in relation to the housing. A free-floating connecting element is rotatably supported between the drive element and the driven element to facilitate relatively unimpeded pivoting of the axle and wheel relative to the housing. The connecting element has two degrees of freedom offset at 90° to one another and aligned radially relative to the axis of rotation to accommodate axle pivoting while assuring smooth transfer of power from the wheel to the driven element as the angular relationship changes between the axle and housing with movement of the wheel over irregular ground surfaces.

Description:
This application claims priority to Application No: DE 10 2007 009084.8, filed 24 Feb. 2007. 
     FIELD OF THE INVENTION 
     The invention relates to a ground wheel drive system on an agricultural machine wherein at least one ground driven wheel is supported for movement by an axle suspension and is connected to a driven implement through a drivetrain. 
     BACKGROUND OF THE INVENTION 
     Demands for increased productivity and performance of agricultural tillage and seeding machines as soil tilling implements or combination cultivating and sowing machines have resulted in large, heavy machines. Such machines include, in particular, soil tilling implements and cultivating machines such as plows, harrows, cultivators, rotary hoes, and the like as well as planters, sowing machines and drilling machines, or combined cultivating and sowing machines, which combine several of the aforementioned implements. The increasing size of these machines and implements results in added weight that needs to be distributed to as large a ground contact area as possible to reduce soil compaction. To distribute the load, two-wheel arrangements are often utilized to create a larger contact area. Two-wheel arrangements generally have a corresponding axle suspension with two wheel axles arranged to move or pivot vertically to adjust to the changing ground contour of irregular ground surfaces. 
     Many implements have drive arrangements which serve to drive an attachment, such as an agitator or a metering device for fertilizers or seed, for example. Such drive arrangements often utilize drive from a ground engaging wheel, whether in a two-wheel arrangement or a single-wheel arrangement, connected through a drivetrain to the driven device on the implement. 
     In wheel arrangements having pivoting axles, drive arrangements must have power transferring mechanisms which can adjust to the movements of the wheel axles and the axle beams. Typically, a universal joint, tapered toothed or bevel gearing is utilized to accommodate the pivoting movements of the wheel. Such solutions, however, are sophisticated in design and are expensive to manufacture. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to specify a drive arrangement of the aforementioned type which overcomes the aforementioned problems. 
     According to the invention, a drive arrangement of the aforementioned type has a drivetrain including a drive element supported on the axle beam and constrained for rotation with the wheel. A rotatably supported driven element is mounted in relation to a supportive housing, and a connecting element is rotatably supported between the drive element and the driven element. The connecting element is supported between the drive element and the driven element so that it is free-floating radially relative to its axis of rotation (that is, arranged so that it is free to move radially). This radial free float feature facilitates relative movements between the drive element and the driven element which occur radially to the axis of rotation of the drive element and the driven element when the axle beam or the wheel pivots relative to the housing. While allowing the free radial float, the connecting element transmits a rotational movement. The connecting element is in this case arranged between the drive element and the driven element and is axially fixed relative to the axis of rotation. 
     The connecting element has a cavity through which the axle beam extends. The axle beam therefore pivots inside the cavity in the connecting element. The connecting element is preferably of annular design and is arranged around the axle beam to optimize compactness. However, the connecting element may also assume other geometric shapes such as, for example, a plate or disc. 
     For transmitting a rotational movement from the drive element to the driven element, the connecting element has sides facing the drive element and the driven element with recesses and/or protrusions or elevations which mesh with protrusions and/or recesses formed on the drive element and the opposite driven element. The meshing of components transmits rotational movement from the drive element to the connecting element and thence to the driven element. The protrusions and recesses are matched to one another in such a way that an elevation can be received by a recess. As the elements rotate, the rotational movement is transmitted by the lateral faces of the elevations and/or recesses bearing against one another. The elevations may be formed on the drive element and the driven element and the recesses only on the connecting element. Inverse arrangements may also be appropriate, however, so that the elevations are formed on the connecting element and the recesses on the drive element and the driven element. It is also possible to form elevations and recesses on one of the elements, which mesh with a corresponding opposite elevations and/or recesses. 
     In one embodiment, the elevations and/or recesses formed on the connecting element are angularly offset by 180° on both sides of the connecting element. The elevations and/or recesses on one side of the connecting element are angularly offset by 90° relative to those on the other side of the connecting element. The elevations and/or recesses on the drive element and on the driven element meshing with the elevations and/or recesses on the connecting element are correspondingly arranged so that the elevations and/or recesses on the drive element and on the driven element are likewise offset by 180° in relation to one another. Pivoting of the axle beam or of the wheel can therefore be accommodated since the connecting element has two degrees of freedom offset at 90° to one another which are aligned radially to the axis of rotation. The connecting element is thereby capable of transmitting rotational movement from the drive element to the driven element and at the same time of permitting radial floating movements in any direction relative to its axis of rotation to accommodate pivoting movements of the wheel. 
     The elevations and recesses have end faces, which preferably are oriented radially to the axis of rotation of their corresponding element (drive element, driven element and connecting element), so that the connecting element is capable, within limited orbits, of free-floating movement radially to its axis of rotation. Sufficiently large force transmission areas are created on the flanks of the elevations and recesses to permit transmission of the rotational movements. It should be pointed out here that end faces are taken to mean the upper face of an elevation and the bottom face of a recess. 
     The elevations and recesses may have curved end faces with each recess meshing with an elevation to form a concavely/convexly curved pair of end faces. This construction results in a concavely curved end face of an elevation meshing with a recess which has a correspondingly convexly curved end face, and vice versa. The curved end face design enables the connecting element to float without any play to optimize guidance or floating support of the connecting element with little wear. End face configurations other than a curved, such as spherical shapes, are also feasible. In addition, the end faces may also be formed other than a curved surface such as a planar surface. A curvature would only reduce the play but would not affect the functionality. Smooth or planar end faces, whether formed on one or both sides or in pairs, are therefore functionally equivalent in use. The same applies to spherical or curved surfaces of the end faces. 
     The assembly drive device comprises a chain drive arranged on the housing and drivingly connected to the driven element of the drivetrain. The driven element may be rotationally locked to a gear or pinion driving the chain drive. The gear itself may constitute a driven element of the drivetrain and be provided with corresponding elevations and/or recesses, which mesh with the connecting element. Instead of the chain drive, other drive arrangements such as V-belt or toothed belt or friction belt drives and toothed gear drives can also be used. 
     The drive arrangement according to the invention is described for a two-wheel arrangement of an agricultural machine but may also be utilized with other pivoting suspension drive axle or the drive element arrangements. 
     The driven implement may be a metering device for fertilizers and seed or an agitator or other device which is used on the agricultural machine or soil tilling implement or the combined cultivating and sowing machine. The drive may also be used, for example, to drive a spraying device or a mixing device for mixing seed with other materials or chemicals. The drive arrangement according to the invention may also be used to drive a combination of one or more devices. 
     The invention and further advantages and advantageous developments and embodiments of the invention will be described and explained in more detail with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective, rear view of a two-wheel axle assembly having a drive arrangement according to the invention, 
         FIG. 2  is a rear, plan view of the drive arrangement in  FIG. 1 , 
         FIG. 3  is an exploded perspective view of the drive arrangement in  FIG. 1 , 
         FIG. 4  is a cross sectional front view of the axle suspension of the two-wheel axle assembly in  FIG. 1 ; and 
         FIG. 5  is a side view of a soil tilling implement drawn by a tractor and having a metering device driven by a drive arrangement according to the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a two-wheel arrangement or axle assembly  10  having an axle suspension  12  supporting axle beams  18 ,  20  which extend through apertures  14 ,  16  on opposite sides of a housing  17 . Wheels  22 ,  24  are supported by the axle beams  18 ,  20  for pivoting relative to the housing  17 . 
     The axle beams  18 ,  20  are of articulated knuckle-joint design, as can best be seen from  FIG. 4 , and comprise a first member  26 ,  28  and a second member  30 ,  32 , which are arranged at right angles to one another. The first members  26 ,  28  are each connected to a wheel axle  34 ,  36 , on which the wheels  22 ,  24  are rotatably supported. 
     The wheels  22 ,  24  support the axle suspension  12  in relation to the ground with the first members  26 ,  28  extending axially, or transversely to the direction of rotation of the wheels  22 ,  24 . 
     The second members  30 ,  32  extend in an upright direction and are rigidly connected to the first member  26 ,  28 . The end areas of the second members  30 ,  32  are constrained for movement together by connecting pins  34 ,  36  and a rigid connecting strut  38 . 
     Guide bushings  40 ,  42  receive pivot pins  44 ,  46  which are fixedly supported on the housing  17  to define fore-and-aft extending pivotal axes located between the first and the second members  26 ,  28  and  30 ,  32 , respectively. 
     The interaction of the components described above is illustrated in  FIG. 4 . The axle beams  18 ,  20  are pivotally supported by their guide bushings  40 ,  42  on the pivot pins  44 ,  46  which in turn are supported on the housing  17 . The axle beams  18 ,  20  therefore can pivot relative to the housing  17  about the longitudinal axis of the pivot pins  44 ,  46 . The axle beams  18 ,  20  therefore define pivoting bodies which allow an up and down movement of the first members  26 ,  28  and of the wheel axles  34 ,  36  and hence of the wheels  22 ,  24  in a vertical direction relative to the ground. 
     The second members  30 ,  32  rigidly arranged at right angles to the first members  26 ,  28  pivot with the first members  26 ,  28 . As one of the wheels  22 ,  24  rolls over an undulation in the ground, for example, the second wheel will move in the opposite vertical direction as the first wheel. The two second members  30 ,  32  extending in a vertical direction are articulated to one another through the connecting strut  38  and the connecting pins  34 ,  36  carried in bearing apertures on the housing  17 . The connecting strut  38  here transmits a resulting pivoting movement of the one axle beam  18 ,  20  to the other axle beam  18 ,  20  so that a pivoting movement of the one axle beam  18 ,  20  gives rise to a pivoting movement of the other axle beam  18 ,  20  in the same direction. The connecting strut  38  and the connecting pins  34 ,  36  therefore constitute connecting structure which articulates the second members  30 ,  32  with one another. If the right-hand wheel  24  as shown in  FIG. 1  runs upwardly over an undulation in the ground, for example, the right-hand axle beam  20  in  FIG. 1  performs an upward pivoting movement and the left-hand axle beam  18  in  FIG. 1  performs a downward pivoting movement. This action is represented by way of example in  FIG. 4  ( FIG. 1  showing a rear view and  FIG. 4  showing a front view). 
     A drive arrangement  48  according to the invention, as is described in more detail below with reference to  FIGS. 2 to 4 , is provided on the left hand axle beam  18  represented in  FIG. 1  (and represented on the right-hand side of the illustration in  FIG. 4 ). 
     The drive arrangement  48  comprises a drive element  52  secured for rotation with the wheel  22  or to a corresponding wheel hub  50 . The drive element  52  is of hollow design so that the corresponding wheel axle  34  can extend through the element. The drive element  52  together with the hub  50  are therefore supported on the corresponding axle beam  18  and move up and down with pivoting movement of the beam  18 . The drive element  52  has two wing-like projections  54 ,  56  which are spaced at an interval of 180° on the circumference of the drive element  52  and which extend axially to the axis of rotation  58  of the drive element  52 . Web-shaped elevations or projections  60 ,  62 , which rise in an axial direction to the axis of rotation  58  of the drive element  52  and have end faces  64  preferably oriented radially to the axis of rotation  58 , are formed on the projections  54 ,  56 . 
     The drive arrangement  48  further comprises a driven element  66  rotatably supported on the housing  17 . The driven element  66  is of hollow design so that the corresponding wheel axle  34  can extend through the element. The driven element  66  is therefore fixed in relation to the housing  17  so that its axis of rotation stays generally fixed relative to the housing. The cavity in the driven element  66  is dimensioned so that under maximum pivoting of the axle beam  18  the axle beam  18  does not impinge against the cavity wall of the driven element  66 . The axle beam  18  can therefore move and be swivelled unimpededly inside the axle beam cavity. 
     The driven element  66  has two wing-like projections  68 ,  70 , which are spaced at  1800  intervals around the circumference of the driven element  66  and which extend axially to the axis of rotation  72  of the driven element  66 . Web-shaped elevations  74 ,  76 , which project in an axial direction to the axis of rotation  72  of the driven element  66  and have end faces  78  preferably oriented radially to the axis of rotation  72 , are formed on the projections  68 ,  70 . 
     The driven element  66  is provided with or connected to a wheel rim, a gear or a pinion  80 , which in turn powers a chain drive structure  82  supported at least in part on the housing  17 . The chain drive  82  is of conventional construction and is connected to a drive element such as a drive shaft  84  ( FIG. 1 ) of an implement or a device to be driven, for example an agitator for a seed tank or a metering device  86  for dispensing seed. 
     A connecting element  88  is arranged between the drive element  52  and the driven element  66 , as can be best seen in  FIG. 3 . The connecting element  88  is of hollow design in the form of a ring, through which the axle beam  18  extends. The cavity in the connecting element  88  is dimensioned so that under maximum pivoting of the axle beam  18  the axle beam  18  does not impinge against the cavity wall of the connecting element  88 . The axle beam  18  can move and swivel unimpededly inside the connecting element cavity. The connecting element  88  has two drive-side recesses  90 ,  92  which are spaced at 180° intervals around the circumference and two driven-side recesses  94 ,  96  also spaced at 180° intervals around the circumference. The drive-side recesses  90 ,  92  are offset by 90° in relation to the driven-side recesses  94 ,  96 . The drive-side, web-shaped elevations  60 ,  62  are oriented towards the drive-side recesses  90 ,  92 , whereas the driven-side, web-shaped elevations  74 ,  76  are oriented towards the driven-side recesses  94 ,  96 . The recesses  90 ,  92 ,  94 ,  96  also have end faces  98 ,  100  which are preferably oriented radially to the axis of rotation  102  of the connecting element  88 . 
     The elevations or projections  60 ,  62 ,  74 ,  76  are matched to the recesses  90 ,  92 ,  94 ,  96  in such a way that they positively interlock in the recesses  90 ,  92 ,  94 ,  96 . The interlocking of the elevations  60 ,  62 ,  74 ,  76  in the recesses  90 ,  92 ,  94 ,  96  define meshing structure that affords floating support for the connecting element  88  between the drive element  52  and the driven element  66 . The floating support assures that the connecting element  88  can move radially in such a way to compensate for the different axial alignments of the axes of rotation  58 ,  72  of the drive element  52  and the driven element  66 , which occur as soon as the axle beam  18  is pivoted. Simultaneously, a rotationally fixed connection between the drive element  52  and the connecting element  88  and between the connecting element  88  and the driven element is maintained. The end faces  64 ,  78 ,  98 ,  100  are preferably of curved design to ensure maximum or optimum interlocking in all pivot positions of the axle beam  18 . The curvatures of the end faces  64 ,  78 ,  98 ,  100  are selected so that the end faces  64  on the elevations  60 ,  62  are concave and the end faces  98  on the recesses  90 ,  92  are correspondingly convex, and that the end faces  100  on the recesses  94 ,  96  are concave and the end faces  78  on the elevations  74 ,  76  are correspondingly convex. This structure results in a positive interlock matched to the movements of the connecting element  88 , so that the connecting element  88  is always optimally guided by the curvatures formed on the end faces  64 ,  78 ,  98 ,  100  while the elevations  60 ,  62 ,  74 ,  76  slide to and fro in the recesses  90 ,  92 ,  94 ,  96  and transmit a rotational movement and a drive torque via their flanks. The positions assumed by the connecting element  88  as the connecting element  88  rotates also encompasses slight angular variations of its own axis of rotation  102  relative to the axes of rotation  58 ,  72 , which is assisted by the curved surfaces of the end faces  64 ,  78 ,  98 ,  100  in such a way that an optimum interlock is also obtained between the end faces  64 ,  78 ,  98 ,  100  in an axial direction. The curvatures of the end faces  64 ,  78 ,  98 ,  100  in a radial direction have a radius of curvature which is equal to the distance of the corresponding end faces  64 ,  78 ,  98 ,  100  from the longitudinal axis of the pivot pin  44  of the axle beam  18  forming the pivot axis. 
       FIG. 5  shows an example of a drive arrangement  48  according to the invention on a combination cultivating and seeding agricultural machine  104 . The combination machine  104  has a frame  112  which extends in the forward direction (from left to right in the drawing) and which is supported on the ground by the wheels  22 ,  24  and axle suspension  12 . At the front end the frame  112  a drawbar  116  is connected through a detachable coupling  120  to a towing vehicle  118  such as an agricultural tractor. 
     Forwardly of the wheels  22 ,  24  a seed box  122  is supported on the frame  112 . The seed is measured out from the seed box  122  by the metering device  86  as the device is driven by the chain drive  82  and the drive arrangement  48  according to the invention. Seed is delivered through seed lines (not shown) to seeding units  124  supported at the rear of the frame  112 . The units  124  include furrow openers  126  which deliver the seed into the furrow and closing wheels  128  for subsequently closing the furrow behind furrow forming coulter structure  130 . 
     Multiple seeding units  124  are spaced transversely along an implement carrier  132  mounted on the frame  112  and extending transversely to the forward direction. Forwardly of the seed box  122  a carrier frame  136  is fixed beneath the frame  112  and carries a pivoting frame  138 . A soil tilling implement  140  such as a disc harrow is supported from the frame  138 . Other soil tilling implements  140  may be used instead of the disc harrow. 
     Although the invention has only been described with reference to one exemplary embodiment, many different alternatives, modifications and variants coming within the scope of the present invention will become apparent to a person skilled in the art in the light of the description above and the drawings.