Abstract:
A forage harvester chopper arrangement is located within a housing provided with an access door mounted for pivoting vertically between a chopping position, wherein access to the chopping arrangement is prevented, and a grinding position, permitting access to the chopping arrangement by a grinding arrangement. A locking arrangement is associated with the access door and an actuator is coupled to the access door and the locking arrangement by a linkage containing lost-motion means which operates such that when moving the access door to its grinding position, the locking arrangement is moved to its unlocked position prior to the access door being raised to its grinding position, and such that when returning the access door to its chopping position, the access door is closed before the locking arrangement is moved to its locked position.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention concerns a chopper arrangement for a forage harvester with a guide arrangement and a access door arranged on a housing at the chopper arrangement, that can be moved by means of an actuator actuated by external forces between a chopping position, in which it closes the housing, and a grinding position, in which it partially opens the housing, so that the grinding arrangement can interact with the chopper arrangement.  
       BACKGROUND OF THE INVENTION  
       [0002]     In forage harvesters, it is useful to sharpen the knives of the chopper arrangement from time to time in order to assure that the knives are sufficiently sharp. In this way, the energy requirement for the chopping are kept low and the quality of the cut is kept high. The chopper arrangement is enclosed by a housing that is provided with openings for the supply and delivery of the harvested crop, but its otherwise closed, in order to prevent a discharge of the harvested crop at undesired locations and a contact of the chopper arrangement with the operator. In order to permit the grinding arrangement to interact with the chopper arrangement, the state of the art provides a access door that can be moved between a chopping position, in which it closes the housing in order to prevent an undesired access to the chopper arrangement, and a grinding position, in which it permits access to an opening in the housing, through which the chopper arrangement can interact with the grinding arrangement. In this position, a visual inspection of the knives and a possible replacement of the knives can also be performed.  
         [0003]     The movement of the access door between the aforementioned positions can be performed by an actuator actuated by external forces, particularly an electric linear motor (DE 41 34 957 A) or a rotating electric motor (EP 0 444 916 A) that is connected so as to drive the access door over a drive mechanism. The position of the access door is detected by sensors, particularly limit switches or linear potentiometers, and the actuator is controlled to correspond. Thereby the access door is retained exclusively in the chopping position by the actuator.  
         [0004]     In certain operating conditions, particularly if the harvested crop is not delivered properly at the outlet of the chopper arrangement and re-circulates with it or jams the chopper arrangement, relatively intense forces can be applied to the cover arrangement, that can also act in form of impulses or beats, and can be transmitted over the drive mechanism to the actuator and the sensor of the position detection arrangement of the cover arrangement. These forces can lead to damage of the actuator or the sensor.  
         [0005]     The problem underlying the invention is seen in the need to overcome the aforementioned problem.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention, there is provided an improved access door control arrangement for a chopper arrangement of a forage harvester.  
         [0007]     An object of the invention is to provide such an access door control arrangement which includes a locking arrangement for securing the door in its chopping position.  
         [0008]     This object is achieved by mounting the access door to the chopper housing by a locking arrangement which may be released from a locked position. The locking arrangement fixes the position of the door independently of any possible retaining force of the actuator, actuated by external forces. In this way, the result is that any possible forces acting on the door, that can be caused particularly by harvested crop jamming itself up, can be deflected by the locking arrangement and not transmitted to the actuator and, if necessary, to the sensor for the detection of the position of the access door or transmitted only to a lesser degree. Thereby damage to thee elements need not be feared.  
         [0009]     One solution is to use the actuator, actuated by external forces, that moves the access door also for the retaining and releasing of the locking arrangement. This is performed to great advantage, in which the actuator at first brings the locking arrangement into the release position for the opening of the access door and in a time sequence, subsequently moves the access door into the grinding position. Analogously, the access door is first moved into the chopping position and then the locking arrangement is secured.  
         [0010]     In order to attain this operating procedure, a solution is to provide a connection between the actuator and the cover arrangement, that permits a certain lost-motion. If the actuator moves within this lost-motion, then it opens or closes the locking arrangement. Upon overcoming the lost-motion, the access door is moved. This can be attained by any desired mechanical device, for example, by an elongated hole that is engaged by a pin or by a cam that interacts with an opposing element. The drive arrangement between the actuator and the locking arrangement can be rigid or buffered by a spring.  
         [0011]     In a preferred embodiment of the invention, the locking arrangement includes a locking bar element that moves in a linear direction in a corresponding guide ion order to avoid tilting. IN the locking position, the locking bar element engages an associated opening. Here it does not matter whether the locking bar element is attached to the access door and engages an opening in the housing or inversely is attached to the housing and engages an opening in the cover arrangement. In another embodiment, the locking bar element performs a rotating movement.  
         [0012]     Finally, the actuator, actuated by external forces, is connected with the access door and the locking arrangement preferably over a shaft. The actuator may be a linear motor that preferably drives the shaft by means of gears. The shaft pivots or rotates the access door between the chopping position and the grinding position and also moves the locking arrangement in a linear motion or in a rotary motion. In another embodiment, the actuator moves the access door in a linear direction. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The drawings shown an embodiment of the invention that shall be described in greater detail I the following.  
         [0014]      FIG. 1  is a schematic left side view of a forage harvester including a chopper arrangement.  
         [0015]      FIG. 2  is a vertical cross section through the chopper arrangement, with the guide arrangement and the access door arranged on its upper side.  
         [0016]      FIG. 3  is a schematic left front perspective view of the access door in the chopping position.  
         [0017]      FIG. 4  is a side view of the shaft and the access door with the lost motion means that makes it possible for the actuator to first unlock the locking arrangement before raising the access door to its grinding position, and to first lower the access door to its chopping position before moving the locking arrangement to its locked position.  
         [0018]      FIG. 5  is a cross section through the guide of the locking bar element of the locking arrangement. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]     A self-propelled harvester  10 , shown in  FIG. 1 , includes a frame  12  supported on front driven wheels  14  and rear steerable wheels  16 . The forage harvester  10  is controlled from an operator&#39;s cab  18  from which a harvested crop recovery arrangement  20  can be viewed. Crop, for example, corn, grass or the like, taken up from the ground by the crop recovery arrangement  20  is conducted to a chopper arrangement  2  in the form of a chopper drum, that chops the crop into small pieces and delivers these pieces to a conveyor arrangement  24 . The crop leaves the harvesting machine  10  to an accompanying trailer through a discharge duct  26  that can be rotated about a vertical axis and which may be repositioned in height. A post chopper reduction arrangement or kernel processor  28 , that can be removed if desired, is arranged between the copper arrangement  2  and the conveyor arrangement  24 , through which the crop to be conveyed is conducted tangentially to the conveyor arrangement  24 . The invention could also be applied to a towed or an attached forage harvester.  
         [0020]      FIG. 2  shows the attachment of the chopper arrangement  22  about whose circumference knife holders  30  are distributed with knives  32 , fastened by screws  34 , in a drum-shaped housing  36  that is approximately coaxial with the axis of rotation of the chopper arrangement  22 . A shear bar  38  is arranged at an inlet opening  40  of the housing  36  to which harvested crop is supplied by the harvested crop recovery arrangement  20 . The knives  32  cut the harvested crop in interaction with the shear bar  38 . Then the harvested crop reaches the posit chopper reduction arrangement  28  through an outlet opening  42  of the housing  36  or, in case that the post chopper reduction arrangement has been removed, it reaches the conveyor arrangement  24  directly.  
         [0021]     An access door  44  is located on the upper side of the housing  36  that can be pivoted between a chopping position, shown in solid lines, and a grinding position, shown in dashed lines, supported in bearings about an axis  46  extending parallel to the axis of rotation of the chopper arrangement  22 . The access door  44  encloses the housing  36  in the upward direction, so that no harvested crop can exit there and unintended contact with the knives  32  by an operator should not be feared. In the grinding position, the access door is pivoted upward and opens an opening  48  on the upper side of the chopper arrangement  22 .  
         [0022]     The knives  32  of the chopper arrangement  22  can be examined visually by an operator through the opening  48 . Moreover, a grinding arrangement  50  can operate upon the knives  32  through the opening  48  when the access door  44  is in the grinding position, the grinding arrangement consisting of a carriage  52  with a grinding stone  54  arranged on its underside as well as guide elements  56 ,  58 . In its rest position, the carriage  52  is located to the side alongside the chopper arrangement  22 , so that then pivoting of the access door  44  becomes possible without the danger of a collision with the grinding arrangement  50 . During the grinding, the carriage  52  with the grinding stone  54  is guided through means of the guide elements  56 ,  58 , that extend parallel to the direction of rotation of the chopper arrangement  22 , along the width of the rotating chopper arrangement  22 , and preferably in the opposite direction to the direction of rotation use in the harvesting operation, that is shown in  FIG. 2  extending in a counterclockwise direction, it is guided along the rotating chopper arrangement  22 , in order to sharpen the knives  32 . The grinding process can be initiated by the operator or an appropriate sensor arrangement, that detects dull knives  32  (see DE 102 35 919 A and references cited therein). The details of the grinding arrangement  50  are disclosed by DE 199 10 757 A, whose disclosure is incorporated into the present application by reference.  
         [0023]     It can be seen that the access door  44  must be brought into the grinding position before the grinding process, and it must be brought back into the chopping position for the resumption of the harvesting operation. The movement of the access door  44  is performed by mean of an actuator  60 , actuated by external forces, and a mechanism, that is shown in  FIG. 3 . Thereby the grinding process can be initiated automatically or by the operator in the operator&#39;s cab  18  and be performed automatically without any need for the operator to leave the operator&#39;s cab  18 . Thereby, an electronic control arrangement  64 , shown schematically, controls the grinding arrangement  50  and also controls the actuator  60 , actuated by external forces, of the access door  44  in order to bring it into the grinding position before the grinding process and subsequently to bring it into the chopping position.  
         [0024]     The actuator  60  is a linear motor, known in itself, that contains an electric motor  62 , whose rotary movement is converted into linear movement by appropriate elements, such as a rack that interacts with a gear driven by the electric motor  62 . The electric motor  62  is arranged in a housing  66  that is located to the side alongside the access door  44  with respect to the direction of operation of the forage harvester  10 , an the housing extends vertically. On its upper side, the housing  66  is connected directly or indirectly to the frame  12  of the forage harvester  10 . A drive rod  68  is located on the underside of the housing  66  and it can be moved in the vertical direction by the electric motor  62 . A sensor  70  is located in the housing  66 , or outside of it, and takes the form of a rotary or linear potentiometer that is arranged to detect the actual position of the drive rod  68 . The electric motor  62  and the sensor  70  are connected with the electronic control arrangement  64  which also controls the grinding arrangement  50 , as is shown schematically in  FIG. 3 . In place of an actuator  60  operating on a linear basis, a rotary actuator could also be used. In place of an electric drive, a pneumatic or hydraulic drive could also be used for the actuator  60 .  
         [0025]     A lower region of the drive rod  68  is connected in a joint to a pivot lever  76  over a horizontal, transverse coupling pin  72 . The pivot lever  76  is fastened to a shaft  78  which extends parallel to the axis of rotation of the chopper arrangement  22 . The shaft  78  is supported in bearings at both ends, not shown, free to rotate, on the frame  12  about its longitudinal axis, which corresponds to the axis  46 . The elongated hole  74  and the coupling pin  72  permit a conversion of the linear movement of the drive rod  68  into a pivoting movement of the shaft  78 . For this purpose, any other desired devices could be used, such as a joint.  
         [0026]     Furthermore, a rear side of the access door  44  is formed to define a pair of laterally spaced sleeves  80  and  82  received on the shaft  78  for free pivotal movement, whereby the access door  44  is mounted for pivoting vertically about the axis  46 . As shown in  FIG. 4 , the drive connection between the shaft  78  and the access door  4  is performed by an elongated hole connection, that provides an initial rotational lost-motion, in which the access door  44  is not yet moved. This lost-motion connection is composed of a lever  84  applied to the upper side of the shaft  78 , an upstanding bracket  88  joined to an upper surface of the door  44  at a location beside the lever  84 , with the bracket  88  containing an elongate hole  86  that extends vertically at a radius about the axis  46 , and a coupling pin  90  extending parallel to the axis  46 , which is carried by the lever  84  and is received within the elongated hole  86 .  
         [0027]     Moreover, two levers  92  are fastened to the shaft  78  and are provided with openings at their outer ends through which coupling pins  94  extend which are attached to forks  96  and which extend parallel to the axis  96 . These openings are configured as elongated holes. The forks  96  are attached to rods  98  that extend forward and approximately in the horizontal direction. The rods  98  are connected with two rods  102  over joints  100 . The joints  100  can move about axes extending parallel to the axis  46 . The second rods  102  also extend forward and approximately in the horizontal direction. In the embodiment shown, the rods  98  can be adjusted in their length. But this characteristic is not an absolute requirement, and non-adjustable rods could also be used. The second rods  102  extend into cylindrical guides  104  that are fastened to the access door  44 , in whose opposite ends cylindrical locking bar elements  106  are supported in bearings which are coaxial to the guides  104  and the second rods  102 . As can be seen in  FIG. 5 , a preloaded helical spring  108  is arranged within each of the guides  104  and coupled between adjacent ends of the second rods  102  and the locking bar elements  106 , both of which are supported in bearings, free to slide. The springs endeavor to press the locking bar elements  106  away from the second rods  102  and to transmit rearward or forward movement of the second rods  102  to the locking bar elements  106 .  
         [0028]     On the rear side of the part of the housing  36  that is located immediately in front of the access door  44  in the direction of operation, an angled border  110  is provided. Two cylindrical openings  112  are provided in the border, that extend coaxially to the locking bar elements  106 .  
         [0029]     Thus, it will be appreciated that the actuator  60  is coupled to the access door  44  and the locking bar elements  106  by a linkage including the shaft  78 , the lever  76  coupled between the actuator  60  and the shaft  78 , the lever  84  coupled between the shaft  78  and the access door  44 , the levers  92  coupled between the shaft  78  and the first rods  98 , and the second rods  102  connected between the first rods  98  and the compression springs  108 , which are in turn, coupled to the locking bar elements  106 .  
         [0030]     The following description of the method of operation begins with the fact that the actuator  60 , actuated by external forces, is located at first in its upper end position. Then the shaft  78  and the levers  84 ,  92  coupled to it are located in the position shown in  FIG. 3 . The locking bar elements  106  penetrate the openings  112  in the border  110  of the part of the housing  36  ahead of the access door  44 . Thereby the access door is located in the chopping position and is locked by the locking bar elements  106  at the housing  36 . In case that harvested crop is unintentionally carried along around the chopper arrangement  22  or even jams it, so that relatively high radial and/or tangential forces are applied to the access door  44 , these forces are deflected by the locking bar elements  106  to the housing  36  and are not absorbed by the actuator  60  or only absorbed to a reduced degree. Damage to the actuator  60  or the sensor  70  is therefore not to be feared.  
         [0031]     If the control arrangement  64  initiates a grinding process automatically or upon an operator input, the actuator  60  is activated. It moves the drive rod  68  downward, whose movement is transmitted over the coupling pin  72  to the pivot lever  76 . The latter performs a rotation of the shaft  78 , that is shown in  FIG. 3  as a clockwise movement. In view of the positions of the lever  84 , the elongate hole  86  and the coupling pin  90 , at first there is no movement that is transmitted to the bracket  88  and to the access door  44 , but only a movement of the coupling pin  90  relative to the elongate hole  86 . Thereby the access door  44  is not yet being raised.  
         [0032]     On the other hand, the elongate openings in the levers  92  are so disposed relative to the coupling pins  94  that the rotation of the shaft  78  is immediately converted into a linear movement over the second levers  92 , the coupling pins  94  and the forks  96 , which is transmitted to the locking bar elements  106  over the first rods  98 , the joints  100 , the second rods  102  and the springs  108 . Thereby the locking bar elements  106  are moved to the rear, opposite to the direction of operation and withdrawn from the openings  112 . Thereby the locking arrangement formed by the elements cited in this section is released and the access door  44  is no longer locked to the part of the housing  36  located in front of it.  
         [0033]     The positions of the lever  84 , the elongate hole  86  and the coupling pin  90  are selected in such a way that a transmission of the rotational movement of the shaft  78  to the bracket  88  and the access door  44  is performed only slightly after the locking of the locking bar elements  106  have been released from the openings  112 . Following this, the access door  44  is rotated upward against the force of gravity and to the rear into the grinding position. During this process, the position of the drive rod  68  is detected by the sensor  70  and continuously monitored by the control arrangement  64 . The latter causes the actuator  60  to be de-energized as soon as the access door  44  has reached the grinding position.  
         [0034]     Now the grinding process or an inspection of the knives  32  by the operator can take place. Since the access door  44  is now in a definite position at a distance from the grinding arrangement  50 , there is the possibility of arranging sealing elements, not shown, at the extreme front face of the access door  44 , which are affected relatively little by the sparks generated during the grinding process. This makes possible an improved sealing about the access door  44  of the housing  36  when in the chopping position.  
         [0035]     After the conclusion of the grinding process and the other operations, the access door  44  is again brought into the chopping position under the control of the control arrangement  64 . For this purpose, the actuator  60  is induced to raise the drive rod  68 . Then the shaft  78 , in  FIG. 3 , rotates in the counterclockwise direction. The access door  44  inks downward and to the front under the force of gravity and/or the effect of the lever  84  on the coupling pin  90 , and finally reaches the chopping position. The elongate holes in the second levers  92 , which engage the coupling pins  94 , is dimensioned in such a way that the locking bar elements  106  extend to the front over the order of the access door  44  only when the chopping position has been reached, since the locking bar elements  06  could not previously enter into the openings  12 . The springs  108  prevent elements of the locking arrangement from being damaged when the openings  112  and the locking bar elements  106  are not aligned with each other for any reason whatever. But it would also be conceivable to omit the springs  108 . In this way, the locking bar elements  106  again extend into the openings  112  and the access door  44  is locked by the actuator  60  in the chopping position.  
         [0036]     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.