Abstract:
A gate latch mechanism is provided on a round baler to pull a gate into a closed position and to lock it during baling operation. Bearings of an actuator on the gate and on the latch are located such that during the closing movement of the gate by means of the actuator, said actuator experiences a movement away from the bearing of the gate thereby allowing a locking pin to move over the latch and to overcome an early interference with the latter.

Description:
FIELD OF THE INVENTION  
       [0001]    This invention relates to a gate latch mechanism between a gate carrier having a latch, and a gate having a locking pin and being journalled about a bearing on the gate carrier by means of an actuator. 
       BACKGROUND OF THE INVENTION  
       [0002]    DE 40 12 755 C1 discloses a round baler where a gate is pivoting about a horizontal axis on the chassis of the round baler between a closed and an open position, whereas this axis is located on the top front area of the gate. On the chassis of the round baler is also provided a latch with a recess, in which a locking pin on the gate may be received and captured until said latch is moved vertically towards an open position. The gate moves into its closed position based on its own weight. During this movement the gate is supported by a hydraulic cylinder resting on and thereby depressing the latch. Once the gate has reached the closed position the hydraulic cylinder retracts and moves the latch upwardly to hold the locking pin. Another example of such a baler is Deutz Fahr round baler RB 4.4. 
         [0003]    In another type of a round baler the gate is journalled about an axis substantially in the center of a bale chamber, see for example EP 1308079 A1 or Vermeer round baler 504 HE. In this case the weight of the gate is not sufficient to overcome the tension in the belts, friction in the bearings, obstructions by crop etc. to safely reach the closed position, where it can be locked. Here a more complicated locking mechanism is necessary to securely move and hold the locking pin in the closed position. 
       SUMMARY OF THE INVENTION  
       [0004]    In view of the foregoing it can be seen that there is a need to provide a gate latch mechanism, which is simple and reliable and does not obstruct the path of the locking pin moving towards the locking position. 
         [0005]    By means of this teaching the actuator, like a hydraulic, electric or pneumatic motor, may pull the gate down and at the same time raise the latch without obstructing the path of the locking pin. Due to a tilting movement of the actuator about its bearings during the closing movement of the gate an additional linear movement is created, which moves the latch down to clear the way for the locking pin. This additional linear movement compensates for the contraction of the actuator. Obviously the given equation allows multiple adjustments of the location of the actuator and the latch to the weight of the gate, the speed to move it up and down, the force needed to close it and keep it closed, etc. 
         [0006]    Under circumstances with little forces breaking the downward movement of the gate, it might be sufficient to use one actuator on one side of the baler to raise and one to lower the gate on the other side. However, when stronger forces apply having two single acting actuators working in different directions on each side of the baler, would be better, since this would avoid bending and torsion forces. The safest and least space consuming solution however would be the use of one double acting actuator per side. 
         [0007]    Using a curved profile on the receiving contour will allow the locking pin to slide over it and/or provide clearance such that no undue friction or interference happens between the pin and the latch. The curve may be of any form, which follows the movement of the locking pin. This does not exclude, that in one extreme the profile is flat and straight—it is just helpful if the profile corresponds with the path of the locking pin. 
         [0008]    A protrusion in the receiving surface of the latch may help to better catch and release the locking pin at the beginning and end of its way over the receiving contour. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]    An embodiment of the invention is described in more detail below with reference to the accompanying drawings wherein: 
           [0010]      FIG. 1  is a schematic side view of a round baler with a gate latching mechanism according to the invention; 
           [0011]      FIG. 2  illustrates the gate latching mechanism in a position, in which it receives a locking pin; 
           [0012]      FIG. 3  illustrates the gate latching mechanism in a position, in which the locking pin slides on a receiving contour; and, 
           [0013]      FIG. 4  illustrates the gate latching mechanism in a position, in which the locking pin enters into a locking position. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    With reference now to the drawings it will be seen that  FIG. 1  shows a round baler  10  having a frame  12 , wheels  14 , a pick-up  16 , a tongue  18 , a gate  20 , and a gate latching mechanism  22 . 
         [0015]    The round baler  10  is completely described in EP 1308079 A1, which description is incorporated by reference hereby. 
         [0016]    The frame  12  contains a front gate carrier  8 , that is fixed in its position, and that carries the gate  20 , which can move vertically between a closed and an open position to form or release a bale. The gate carrier  8  is composed of side walls, struts, rolls etc. forming a substantially stiff unit in the front area of the frame  12 . The movement of the gate  20  happens about a bearing  24 , which is located substantially in the center area of a bale chamber  26 , although this exact location may vary. 
         [0017]    The wheels  14  serve to support the frame  12  on the ground, whereas the tongue  18  is used to connect the round baler  10  to a tractor or the like, not shown. 
         [0018]    The pick-up  16  collects crop lying on the ground and delivers it rearward into the bale chamber  26 , where a bale is formed therefrom. 
         [0019]    The gate  20  is of the so-called light gate type, which means it contains only rolls  28  and baling means  30  in the form of belts trained over the rolls  28  to form the bale chamber  26 . However, the gate  20  does not include sidewalls, since they are part of the frame  12 . Again, this light gate type is advantageous when using the invention, but not necessary. In  FIG. 1  the gate  20  assumes its lower and closed position, i.e. in which the bale chamber  26  is closed. 
         [0020]    The gate latching mechanism  22  contains an actuator  32 , a latch  34  and a locking pin  36  and is provided at least on one side of the round baler  10  outside the bale chamber  26 . 
         [0021]    The actuator  32  is formed as a double acting hydraulic motor with a piston moving longitudinally in either direction. At its upper end area the actuator  32  is journalled on the gate  20  by way of a bearing  38  and in a lower end area by way of a bearing  40  on the latch  34 . 
         [0022]    The latch  34  is of an elongated form, which has a bearing  42  at one end, namely facing the gate carrier  8 , a receiving contour  44  at the opposite end and on the upper side, a hook portion  46  between the bearing  42  and the receiving contour  44 , being open upwardly, and the bearing  40  between the receiving contour  44  and the bearing  42 . In this case the bearing  42  is located between the hook portion  46  and the bearing  42 . The bearing  42  is fixed on the gate carrier  8  and is formed by a pin, shaft or the like and a hole, which each may be on the gate carrier  8  or on the latch. The receiving contour  44  extends over about ⅖ of the latch  34  and is slightly bent upward to form a convex curve. The hook portion  46  is formed by a step  48  at the end of the receiving contour  44  facing the bearing  42 , whereas said step  48  is sized and shaped such, that it can securely hold the locking pin  36  in its locked position. In the area of the bearing  40  the latch  34  is slightly higher than in its remainder to provide sufficient space and strength to receive the bearing  40 , which again is formed as a pin and a hole. Both bearings  40 ,  42  are oriented in the same direction. The latch  34  may be formed as a single piece or as an assembly of two parallel pieces of sheet metal connected to each other. The area, where the hook portion is located is the smallest and gives some flexibility to the latch  34 . 
         [0023]    The locking pin  36  is formed by a rigid pin or rotating roll or the like on such pin, provided on the gate  20  at a position, which moves the locking pin  36  along the receiving contour  44  and into the hook portion  46  when the gate  20  closes the bale chamber  26 . 
         [0024]    Starting from this description various momentum arms are generated, namely: 
         [0025]    a) a moment arm L 2  extending from the bearing  24  of the gate  20  perpendicular to the longitudinal axis of the actuator  32 ; 
         [0026]    b) a moment arm L 3  extending from the bearing  24  of the gate  20  to and perpendicular onto a line perpendicular on the receiving contour  44 , where it is contacted by the locking pin  36 ; 
         [0027]    c) a moment arm L 1  extending from the bearing  42  of the latch  34  perpendicular to the longitudinal axis of the actuator  32 ; 
         [0028]    d) a moment arm L 4  extending from the bearing  42  of the latch  34  to and perpendicular onto the line perpendicular on the receiving contour  44 , where it is contacted by the locking pin  36 ; 
         [0029]    In order to achieve a movement of the locking pin  36  over the receiving contour  44  into the hook portion  46 , the relationship of L 2 /L 3  divided by L 1 /L 4  should be bigger than 1.5. 
         [0030]    It can be seen in  FIGS. 2 through 4 , that during the closing movement of the gate  20 :
       actuator  32  retracts actively and thereby pulls the latch  34  up and the gate  20  down;   actuator  32  tilts about the bearing  40  towards the gate carrier  8  and the gate pin  36  pushes down the latch  34  thereby, whereas the contact pressure of the pin  36  is kept minimal by the simultaneous downward movement of the actuator  32  due to its connection with the gate  20 ;   latch  34  moves down and the locking pin  36  slides against and on the latch  34  until it falls into the notch;       
 
         [0034]    In other words a triangle, the corners of which are defined by bearings  24 ,  38  and  40 , gets flatter and longer during the closing movement of the gate  20 , thereby pushing the latch  34  down an amount, which corresponds to the radial path of the moving locking pin  36  with respect to the stationary latch  34 . 
         [0035]    Finally  FIG. 4  shows, in dashed lines, the latch  34  in its raised position, in which the locking pin  36  is captured. 
         [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.