Abstract:
A ground engaging tool that oscillates in a motion, relative to the ground, that is substantially vertically upward, and then downward and forward in a direction in which the apparatus is moved.

Description:
TECHNICAL FIELD  
         [0001]    This invention relates generally to ground engaging tools and, more particularly, to a ground engaging tool that exhibits an oscillating motion.  
         BACKGROUND  
         [0002]    Conventional ground engaging tools, such as tools used to do primary tillage (sometimes referred to as “rippers”), use a lot of energy and often wear out the ground engaging tool (hereinafter referred to as a “GET”) in a relatively short time (e.g., after 100 hours of use). An example of such a tool is shown in U.S. Pat. No. 5,499,686, issued Mar. 19, 1996, to Paul D. Parker for a DEEP TILLAGE WINGED SWEEP. The fracture energy is high because the soil tends to be forced and moved in a horizontal or forward direction rather than a vertical direction. The friction energy, which wears out the GET, is high because of the soil pressure on the GET and the high relative velocity between the soil and the GET. Conventional rippers generally leave the soil surface in an undesirable state. Additional operations and costs are needed to redo the soil surface to a smooth condition. These additional operations damage the density profile of the soil, reducing the crop yield.  
           [0003]    The present invention is intended to overcome or minimize the above-described problems.  
         SUMMARY OF THE INVENTION  
         [0004]    According to one aspect of the invention, a tilling apparatus includes a ground engaging tool that oscillates in a motion, relative to the ground, that is substantially vertically upward, and then downward and forward in a direction in which the apparatus is moved.  
           [0005]    According to another aspect of the invention, a linkage assembly for a ground engaging tool includes a four-bar linkage assembly that causes the ground engaging tool to repeatedly move in a first direction to lift a section of the ground, and then a second direction to position the ground engaging tool under the next section of ground.  
           [0006]    According to another aspect of the invention, in a vehicle having a tilling apparatus movably associated with the vehicle, the tilling apparatus includes a ground engaging tool, and a linkage assembly operatively connected to the ground engaging tool to cause it to oscillate in a motion, relative to the ground, that is substantially vertically upward, and then downward and forward.  
           [0007]    According to another aspect of the invention, a tilling method using a tilling apparatus includes repeatedly moving a ground engaging tool in a first direction to lift a section of a material being tilled, and then a second direction to position the ground engaging tool under the next section of material being tilled. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 shows an example of a ground engaging tool according to an embodiment of the present invention;  
         [0009]    [0009]FIG. 2 shows an example of a linkage assembly according to an embodiment of the present invention for producing an oscillating motion;  
         [0010]    [0010]FIG. 3 is an explanatory diagram of the movement of the ground engaging tool in a lift phase;  
         [0011]    [0011]FIG. 4 is an explanatory diagram showing different centers of rotation of the linkage assembly;  
         [0012]    [0012]FIG. 5 is an explanatory diagram showing a first center of rotation; and  
         [0013]    [0013]FIG. 6 is an explanatory diagram showing a second center of rotation. 
     
    
     DETAILED DESCRIPTION  
       [0014]    [0014]FIG. 1 shows a ripper  100 , as one embodiment of the present invention, having a ground engaging tool or GET  101  for fracturing compacted soil  110 . The ripper  100  and GET  101  are being pulled from left to right in FIG. 1 to create the fractured soil  120 . As the GET  101  is pulled from left to right, it exerts a force A on the compacted soil. This force A has two force components, B and C. Force component B is perpendicular to the lifting surface  101 ′ of the GET  101 , and tends to lift the soil. Force component C is a smaller force than force component B and is exerted in a direction perpendicular to force component B. Force component C tends to push the soil forward as it is being lifted by the GET  101 . The total energy required to pull the GET  101  in the direction shown in FIG. 1 is equal to the energy required to fracture the soil plus the energy expended due to friction between the GET  101  and the soil.  
         [0015]    [0015]FIG. 2 shows a four-bar linkage assembly  200  for operating the GET  101 . If it is desirable to actuate the oscillation cycle without auxiliary power, such a four-bar linkage system can be used. A lower link  201  is pivotally connected at one end to lower arm  101 A of a shank portion of the ripper  100  and at the other end to a frame  203 , and an upper link  202  is pivotally connected at one end to upper arm  101 B of the shank portion of the ripper  100  and at the other end to the frame  203 . The four-bar linkage assembly  200  is formed by the lower link  201 , the upper link  202 , the shank portion of the ripper  100  (having lower arm  101 A and upper arm  101 B), and the frame  203 .  
         [0016]    A spring  204  (FIG. 2) may be provided to improve the jab of the GET  101 . The spring is compressed during lift of the GET  101 , and its spring energy is used to accelerate the jab speed of the GET  101 . Different types of springs could be used. By way of example only, such springs might include a mechanical pull spring, a leaf spring, a pneumatic spring, and a hydraulic spring with accumulator. Instead of a spring, other acceleration generating devices could be used. By way of example only, such other acceleration generating devices might include a hydraulic cylinder with secondary power source and a linear electric motor/generator connected to a capacitor.  
         [0017]    The path of the oscillation of the GET  101 , relative to the main frame  203  of the ripper  100  is upward and rearward during lift, as shown by vector V 1  in FIG. 3. However, because of the forward motion of the frame  203  (see vector V 2  in FIG. 3), the GET  101  will tend to move generally vertical relative to the soil during the lift portion of the cycle, as shown by vector V 3  in FIG. 3, in the direction of minimal resistance (minimum fracture energy). During the jab portion of the cycle, the GET  101  moves downward and forward. The forward speed of the GET  101  may exceed the forward travel speed of the frame  203 , so that the GET  101  “catches up.” 
         [0018]    As shown in FIG. 4, the four-bar linkage assembly  200  has more than one center of rotation. A first center of rotation (center of rotation # 1 ) is formed when the ripper  100  is in its lowest position, and a second center of rotation (center of rotation # 2 ) is formed when the ripper  100  is in its uppermost position. The centers of rotation are defined as the intersection between imaginary lines extending from each link in the length directions of the links, as shown by the dashed lines. As can be seen in FIG. 4, the center of rotation for the ripper  100  and, therefore, the GET  101  moves a relatively long distance in the fore/aft direction, as the ripper  100  moves between its uppermost and lowermost positions. When the GET  101  is at its lowermost position (solid lines in FIG. 4, and also shown in FIG. 5), the center of rotation (center of rotation # 1 ) is generally above the GET  101 , and the GET  101  is ready to lift the soil. When the GET  101  is at its uppermost position (dashed lines in FIG. 4, and also shown in FIG. 6), the center of rotation (center of rotation # 2 ) is relatively far forward of the GET  101 , and the GET  101  is ready to jab forward and downward under the next section of soil.  
         [0019]    In FIG. 5, the ripper  100  is at its lowermost position, and the ripper  100  pivots about the center of rotation # 1 . In other words, the center of rotation has an effect as if the ripper  100  is pivotally pinned to the frame  203  at that point. A load pulled through a pin joint forces the force vector to go through the pin joint. Thus, as shown in FIG. 5, the pull force vector extends from the GET  101  through the center of rotation # 1  and towards the towing vehicle. The net force is determined by the addition of the force vectors for the down force and pull force, as shown in FIG. 5.  
         [0020]    In FIG. 6, the ripper  100  is at its uppermost position, and the ripper  100  pivots about the center of rotation # 2 . In other words, the center of rotation has an effect as if the ripper  100  is pivotally pinned to the frame  203  at that point. A load pulled through a pin joint forces the force vector to go through the pin joint. Thus, as shown in FIG. 6, the pull force vector extends from the GET  101  through the center of rotation # 2  and towards the towing vehicle. The net force is determined by the addition of the force vectors for the down force and pull force, as shown in FIG. 6.  
         [0021]    Industrial Applicability  
         [0022]    The GET  101  oscillates in a motion that tends to lift the soil substantially vertically in order to minimize the fracture energy. After lifting, the GET  101  jabs forward and downward to complete the oscillation cycle and position itself under the next section of soil. During lift, the GET  101  experiences minimal relative motion between it and the soil. During the jab portion of the cycle, the average pressure between the soil and the GET  101  is low. Therefore, the oscillation cycle results in lower friction energy and lower wear. In addition, lifting the soil vertically tends to minimize the soil surface disturbance. As one example, the soil can be heaved rather than boiled.  
         [0023]    While the above-described embodiment relates to a ripper device, the invention is not intended to be limited to such a device and, consequently, other ground engaging tools could incorporate the features of the present invention.  
         [0024]    Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.