Abstract:
An arrangement proposed for the wrapping of a bale with a wrapping material is provided with a drive element that is driven only briefly at the beginning of the wrapping process over a clutch arrangement and which permits the bale to carry the wrapping material along during the remainder of the wrapping process.

Description:
FIELD OF THE INVENTION 
   The invention concerns an arrangement for wrapping a bale with wrapping material, with a drive element, particularly a drive roll, which withdraws the wrapping material from a roll, and a baler equipped with such an arrangement. 
   BACKGROUND OF THE INVENTION 
   DE-A1-100 11 158 shows a baler with an arrangement for wrapping a bale with wrapping material. The wrapping material is withdrawn from a supply roll by means of a drive roll. The arrangement is provided with a sensor which determines whether the wrapping material is wrapped around the drive roll and is therefore not properly conducted to the bale. If the sensor detects a malfunction, then the wrapping process is stopped. 
   SUMMARY OF THE INVENTION 
   The problem underlying the invention is seen in the fact that such an arrangement for the wrapping of a bale breaks off the wrapping process only after the wrapping material has wrapped itself around the drive roll. In order to make the arrangement, or a baler equipped with such an arrangement, ready for further operation, the wrapping material must be removed from the drive roll, which is time consuming and labor intensive. 
   This problem is solved according to the invention by way of an arrangement that is made available for the wrapping of a bale, which prevents the wrapping material from wrapping itself around the drive roll, or generally around a drive element or jams up, if it is not wrapped properly around the bale. By the provision of a clutch arrangement it is possible to drive the drive arrangement only for a brief time interval at the beginning of the wrapping process, in order to initiate the wrapping process. After sufficient wrapping material or material has been withdrawn from the roll or the supply, in order to reach the region of the bale so as to be grasped by it, the drive of the drive element is stopped. In this way, no further material is withdrawn from the supply by the drive element. If the wrapping material has been conducted to the bale properly, it is grasped by the latter. Since the clutch permits the wrapping material to be carried along by the bale, and this process is not blocked by the drive element, the bale can be automatically wrapped with wrapping material. On the other hand, if the wrapping material is not grasped by the bale, then it is not withdrawn from the supply by the drive element. 
   If the clutch arrangement connects the drive element selectively with a drive shaft, then provision can be made for this drive shaft to be permanently connected with a drive which, for example, also puts the bale into rotation. The drive shaft may, for example, be connected over a belt drive with a driven roll, which also operates upon the bale. 
   If the clutch arrangement is provided with a free wheeling clutch, it can permit an unhampered movement of the drive element in one direction and make possible the transmission of torque in a second or opposite direction, particularly if the drive element is not driven. 
   The free wheeling clutch can be arranged between the drive shaft and the drive element in such a way that the drive shaft can move freely in the drive element in its normal direction of rotation when the drive element is not driven or should not be driven. 
   In the opposite direction, a transmission of torque is possible. This can be applied, for example, to brake the drive element that is driven by the wrapping material grasped by the bale, in that its rotational speed is limited by the free wheeling clutch to the rotational speed of the drive shaft. 
   Such a free wheeling clutch is particularly useful when the drive shaft is driven permanently. Here permanently is understood to mean that the drive shaft is driven at least during the wrapping process. In a usual arrangement in which the drive shaft is connected over a belt drive with a roll that put the bale into rotation, provision can also be made for the drive shaft to be driven during the entire bale formation process. 
   If the drive element is driven at a speed that is lower than the circumferential speed of the bale, a stretching or tensioning of the wrapping material, whose other end is grasped by the bale, can then be attained whereby it can adhere closely to the surface of the bale. 
   The drive of the drive elements can be performed by means that connect the drive shaft with the drive element, fixed against rotation. These means can be configured in the form of a clutch that makes possible a drive of the drive element by the drive shaft when the clutch is in activated condition or is engaged and that provides that the drive element is not driven when the clutch is disengaged. 
   The clutch arrangement can interact with a control or regulating arrangement that can determine in particular the position of the clutch as a function of the progress of the bale formation process or the wrapping process. Such a control or regulating arrangement is frequently provided for the monitoring and control or regulation of the bale formation process or the wrapping process, so that the additional function can be implemented in an arrangement already existing. 
   An arrangement for the wrapping of a bale can be applied in industry to balers that form bales of paper, garbage, textile materials, etc. However such an arrangement is particularly appropriate for an application to an agricultural baler for bales of agricultural harvested crops, since these are usually coupled to a towing vehicle and must be monitored by an operator of this towing vehicle. Malfunctions of a wrapping arrangement are difficult to detect for these operators and are frequently noticed only upon ejection of the bale. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawing shows an embodiment of the invention that shall be described in greater detail in the following. 
       FIG. 1  is a schemtatic, right side view of a baler equipped with a bale wrapping arrangement for wrapping a bale with wrapping material. 
       FIG. 2  is a more detailed illustration of the wrapping arrangement of  FIG. 1 , with a clutch arrangement for the selective drive of a drive element. 
       FIG. 3  is a detailed showing of the clutch arrangement of  FIG. 2 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a baler  10  of generally conventional configuration with a baling chamber  12 . According to the present embodiment, a wrapping arrangement  14  is provided for the wrapping of the bale  16  formed in the baling chamber  12  with wrapping material  18 . 
   The baler  10  may be of a known configuration, that is, with a baling chamber  12  of constant or variable size that is surrounded entirely or in combination with belts, chains or rolls  20 , as in the illustrated embodiment. 
   Such a baler  10  can be applied in agriculture for the formation of bales  16  of harvested crop, such as, for example, straw, hay or grass. However a use in industrial applications is also conceivable. 
   In the present embodiment, the wrapping device or arrangement  14  is provided on the forward side of the baler  10 . The wrapping material  18  is conducted through a slot between two adjacent rolls  20  into the baling chamber  12 , where it is carried along by the bale  16  which has been brought into rotation. The wrapping arrangement  14  may be arranged in a central region of the baler  10  or ahead of, or above, the baling chamber  12 . 
   The bale  16  is wrapped by the wrapping material  18  and is thereby prevented from falling apart after leaving the baler  10 . The wrapping material  18  may be foil, net, cloth, paper or the like. 
   Reference will now be made to  FIG. 2 , in which only sections of the baler  10  are shown and the arrangement  14  is shown in an enlarged view. 
   The arrangement  14  is provided with a housing  22 , a drive roll, designated in the following as drive element  24  and a separating arrangement  26 . The housing  22  contains a floor  27  upon which the wrapping material  18  is stored as a roll  28 . The floor  27  may also be configured in such a way that several rolls  28  can be stored and/or that it contains several steps or troughs in which they can be secured. 
   The drive element  24  is provided on its circumferential surface with a coating with a high friction coefficient and can be brought into rotation. Initially the rotation is used to withdraw the wrapping material  18  from the roll  28 . The roll  28  is located above the support surface of the floor  27  and, when in its operating position, has a region that corresponds approximately to a 6 o&#39;clock to a 9 o&#39;clock position that is brought into contact with the drive roll  24 . The wrapping material  18  is withdrawn from the roll  28  by means of the drive element  24  and is conducted through the slot between adjacent rolls  20  into the baling chamber  12 . In a proper operation, the wrapping material  18  is grasped by the bale  16  and wraps the latter. 
   The separating arrangement  26  is provided with a knife  32  which is fastened to an arm  34  that can pivot about a bearing  36 , in order to intrude into the path of the wrapping material  18  and to separate it or to bring about a tearing off when the wrapping process is completed. The knife  32  is pivoted by means of a hydraulic motor  38  that is actuated by a known electronic control or regulating unit (ECU). 
   Beyond that, the arm  34  is connected with a further arm  48 , free to pivot, whose position is also determined by the hydraulic motor  38 . In the present embodiment a guide arrangement  51  is provided, free to pivot, on the arm  38 . Such a guide arrangement  51  is disclosed in U.S. patent application Ser. No. 10/462,045 filed on 13 Jun. 2003. 
   If the hydraulic motor  38  is in its retracted position, as shown in  FIG. 2 , then the knife  32  is in such a pivoted position that it does not influence the course of the wrapping material  18 . 
   The drive element  24  can be selectively driven by a drive shaft  39  which is connected to the roll  20  over a belt drive  40 , where this roll  20  can be brought into rotation by a drive, not shown. 
   The selective connection of the drive shaft  39  with the drive element  24  is performed over a clutch arrangement  42 , that is provided between the drive shaft  39  and the drive element  24 . 
   Reference will now also be made to  FIG. 3 , which reveals that the clutch arrangement  42  is provided with a free wheeling clutch  44 , which connects the drive shaft  39  in a known manner with the drive element  24  in such a way that the drive shaft  39  can move freely in its usual drive direction in the drive element  24 , in the event a torque transmission between the drive shaft  39  and the drive element  24  happens, which is opposite to the normal direction of movement of the drive shaft  39 . 
   Beyond that, the clutch arrangement  42  is provided with a controllable clutch element  46  which can connect, fixed against rotation, the drive element  24  with the drive shaft  39  as a function of a control signal. 
   The following will explain in greater detail the method of operation of the arrangement  14 . For this purpose reference will be made to  FIGS. 1–3 . 
   If the formation of the bale  16  in the baling chamber  12  is completed, which is determined in known manner by a sensor, not shown, which determines the girth of the bale  16 , for example, mechanically or optically, then the arrangement  14  is activated. This is performed by the control or regulating unit (ECU) controlling the hydraulic motor  38  so as to bring it into the retracted position, as shown in  FIG. 2 . 
   Beyond that, the control or regulating unit (ECU) transmits a control signal to the clutch arrangement  42 . On the basis of this control signal, the clutch element  46  establishes a rigid connection, fixed against rotation, between the drive shaft  39  and the drive element  24 . 
   The drive element  24 , that is now driven in rotation, withdraws the wrapping material  18  from the roll  28  and conveys it in the direction of the bale  18 . Here the guide arrangement  51  supports this action, in that it guides the wrapping material  18  into contact with the bale  16 . 
   After a short time interval, that is designed in such a way that the drive element  24  withdraws such an amount of wrapping material  18  from the roll  28  which is sufficient to reach to the bale  16  and to be grasped by the latter, then the clutch element  46  is controlled by the control and regulating arrangement (ECU) in such a way that the clutch element  46  separates the rigid connection between the drive shaft  39  and the drive element  24 . 
   A further withdrawal of wrapping material  18  from the roll  28  is now performed by the rotating bale  16  which grasps the wrapping material  18  and carries it along on the basis of its rotation and wraps it about itself. 
   In the arrangement shown, the drive element  24 , that is arranged so as to be free on the drive shaft  39 , is brought into rotation by the wrapping material  18  that was withdrawn by the rotation of the bale  16  and will now rotate at a rotational speed that exceeds the rotational speed of the drive shaft  39 . However, on the basis of the free wheeling clutch  44  the rotational speed of the drive element  24  is limited to the rotational speed of the drive shaft  39 . The drive shaft  39 , in turn, is connected with the driven roll  20  over the belt drive  40  in such a way that the circumferential speed of the drive element  24  is limited by the free wheeling clutch  44  to a speed that is lower than the circumferential speed of the bale  16 . The wrapping material  18  is braked by the drive element  24  and is thereby stretched or tensioned. This is desirable in order to bring the wrapping material  18  into close contact with the bale  16  and enclose it tightly. 
   If the wrapping material  18  does not follow the predetermined path and is therefore not grasped by the bale  16 , then no transport of the wrapping material  18  is performed by the bale  16 . Since the drive element  24  is driven by the drive shaft  39  over the clutch element  46  only for a brief time interval at the beginning of the wrapping process, the wrapping material  18  is not withdrawn further from the roll  28  by the drive element  24  and the drive element  24  cannot be wrapped by the wrapping material  18 . 
   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.