Abstract:
A precision hoe opener assembly is provided with improved accuracy of seeding as well as improved control over the opener and packer wheel assemblies. The opener assembly includes a hydraulically-driven parallel linkage assembly, hoe opener, and a packer wheel. The design provides improved seeding accuracy, especially during changes in terrain elevation.

Description:
BACKGROUND 
   The invention relates to agricultural planters, such as hoe openers and seeding tools used in farming operations to distribute seeds into soil. Generally, openers are towed behind a tractor via a mounting bracket secured to a rigid frame of the tractor. These openers may include a ground engaging tool or opener that forms a seeding path for seed deposition into the soil. The ground opener is used to break the soil to enable seed deposition. After the seed is deposited, the opener may be followed by a packer wheel that packs the soil on top of the deposited seed. The packer wheel may be rigidly mounted behind the opener via a structural member or rear frame. Thus, the opener and packer wheel generally move together with the same upward and downward motion. 
   Unfortunately, existing openers do not adequately address the need to accommodate height variation over terrain during seeding or transportation without seeding. It is generally undesirable to pull the hoe opener through soil when merely transporting the opener from one location to another. In addition, during seeding, existing openers do not provide adequate vertical motion of the opener and related assembly without compromising the load on the opener and packer wheel. As a result, variations in the terrain can result in substantial changes in the packing force (e.g., normal force) of the packer wheel on the terrain being seeded by the opener and the draft force of the terrain on the opener. The variable force on the opener can result in loss of control over seeding depth. More specifically, this variation in packing and opener force can result in non-uniform seeding depths and packing density in the terrain being seeded by the planter. 
   Existing openers also require substantial force to raise the planter row unit, including the opener assembly and packing wheel. This results in the use of large hydraulic cylinders to raise the apparatus, due to the overall length and weight of each planter row unit. This hydraulic equipment is costly and takes resources (i.e. hydraulic power) from other portions of the tractor and planter unit. 
   There is a need, therefore, for improved arrangements in precision hoe openers and planters that improve accuracy of the seeding operation. There is a particular need for planters and openers that apply forces to the opener and the packing wheel to improve seeding depth and accuracy. 
   BRIEF DESCRIPTION 
   The present invention provides a novel configuration for precision hoe opener assemblies. This configuration of the opener assembly provides improved accuracy of seeding as well as improved control over the opener and packer wheel assemblies. In an exemplary embodiment, the opener assembly includes a hydraulically-driven parallel linkage assembly. The parallel linkage is coupled to the hoe opener and the packer wheel, and is configured to apply a substantially constant force in a deployed position. These features enhance seeding accuracy, especially during changes in the elevation of terrain. In addition, the configuration enables the hydraulic cylinder to raise the hoe opener and the packer wheel above the ground. The design may be implemented for agricultural planters as well as other implements or applications requiring control of height and/or force of implements. 

   
     DRAWINGS 
     These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
       FIG. 1  is a perspective view of a precision hoe opener assembly in accordance with aspects of the invention, including an opener, a packer wheel, and a parallel linkage assembly; 
       FIG. 2  is a side view of the opener assembly of  FIG. 1 , showing the opener implement and packer wheel assemblies in a deployed position; 
       FIG. 3  is a top view of the opener assembly from  FIGS. 1 and 2 ; and 
       FIG. 4  is a perspective view of an entire planter assembly system, including multiple opener assemblies and the tool bars that they are attached thereto. 
   

   DETAILED DESCRIPTION 
   Turning now to the drawings and referring first to  FIG. 1 , an embodiment of a precision hoe opener assembly is illustrated and designated generally by reference numeral  10 . As will be appreciated by those skilled in the art, hoe opener assembly  10  is a type of row unit, which may be placed on an agricultural implement, such as a planter. Precision opener assembly  10  includes a frame support  12 , mounting brackets  14 , first member  16 , second member  18 , and a linear actuator such as a cylinder  20  (e.g., hydraulic and/or pneumatic piston-cylinder assembly). Cylinder  20  may be hydraulically coupled to a power supply  22  that is used to provide a flow of pressurized hydraulic fluid that displaces a piston rod extending from the cylinder. Precision hoe opener assembly  10  may be towed, or generally moved by a vehicle, such as a tractor. For example, the frame support  12  and frame bracket  14  may interface tool frame tow bar connected to the tractor (not shown) for towing the precision hoe opener assembly  10 . For instance, a plurality of opener assemblies  10  may be mounted in parallel along a tool frame bar to comprise a planter unit. Elements  12 ,  16 ,  18 ,  36  and  20  may be collectively described as components of a hydraulically driven parallel linkage assembly. The parallel linkage assembly may also be referred to as a four bar linkage. As will be appreciated by those skilled in the art, components of opener assembly  10 , such as frame support  12 , mounting brackets  14 , first member  16 , and second member  18 , may be made of any suitable material, such as steel or an alloy. 
   Cylinder  20  is attached to a shank adapter  24  via a pin at the end of the piston rod. The shank adapter  24  is also coupled to shank  26  and opener  28 . Shank adapter  24  may be coupled to shank  26  via fasteners  30 , which allow height adjustments of opener  28 , enabling a variable seeding depth for the opener assembly. Pin  32  is coupled to first member  16  and shank adapter  24 , allowing shank adapter  24  to pivotally rotate about the pin  32  as cylinder  20  extends and retracts. Accordingly, opener  28  moves downward or upward based upon cylinder  20 &#39;s extension or retraction, respectively. Shank adapter  24  may feature several holes to receive a pin coupling the end of cylinder  20  to the adapter. The adapter holes may be used to adjust the angle of cylinder  20  with respect to the parallel linkage assembly, thereby changing the angle and magnitude of cylinder forces. 
   As cylinder  20  retracts, stop plate  34  may press on rear frame  36 , creating a lifting force that is conveyed to packer wheel assembly  38 . The resulting lifting force, caused by cylinder  20 , reduces the packing force of wheel  40  and may eventually lift packing wheel  40  from the terrain. In the embodiment, packer wheel assembly may allow height adjustment of packer wheel  40 , in the form of fastener and slot or an equivalent structure. In some cases, the resulting lifting force may compensate for an increased packing force, caused by terrain elevation changes, thereby increasing seeding accuracy. To facilitate seed deposition during operation, opener  28  is coupled to a seed distribution header  42  via a seeding tube  44 . 
     FIG. 2  illustrates a side view of an embodiment of the precision hoe opener  10 . The figure illustrates the precision hoe opener  10  in a neutral position on generally level terrain. Further, as the terrain elevation fluctuates, the hoe opener position will move upward or downward from the neutral position. Cylinder  20  is extended, thereby deploying the opener  28  downward into the terrain, pressing shank adapter  24  against rear frame stops  46 . In the present context, the deployed position may be used to describe the precision hoe opener  10  in a ground-engaging, working position where the shank adapter  24  is pressed against rear frame stops  46  and opener  28  is engaged with the terrain. For example, while in a deployed position the opener  10  may vertically travel up to eight inches as the opener  28  goes over and maintains contact with the contours of a terrain. During sharp changes in elevation, the opener  28  is maintained at a substantially constant angle with the terrain by the parallel linkage and the expansion and contraction of cylinder  20 . In this deployed position, cylinder  20  also exerts a downward force on packer wheel  40 . When cylinder  20  retracts, opener  28  is lifted from the deployed position, as indicated by arrow  48 . When in the fully retracted position, stop plate  34  presses against contact surface  50 , lifting packer wheel  40  upward. As the opener assembly  10  retracts fully, opener  28  and packer wheel  40  are lifted from terrain  52 . The fully retracted position may be utilized when transporting the planter between fields, to minimize wear and tear of the opener. 
   As will be appreciated by one skilled in the art, the configuration of shank adapter  24 , first member  16  and rear frame  36  allows the actuator to pivotally move shank  26  and opener  28  through an angular range independently of packer wheel assembly. That is, in the range of motion between stop plate  34  and rear frame stops  46 , shank adapter  24  and cylinder  20  cause only movement of the opener  28 . In the embodiment, while the opener  28  and actuator  20  are in this “independent” range of motion, the precision hoe opener may not be in a deployed position, i.e. the opener  28  may be removed from contact with the ground. Further, this movement of the opener  28  directly changes the angle between opener  28  and the terrain. In contrast, when in a deployed position, the opener  28  and the terrain are maintained at a substantially constant angle by the parallel linkage assembly. The arrangement may also be helpful as the hoe opener  10  encounters large clods or trash and the actuator  20  is retracted, the shank adapter is released from contact with the frame stops  46 , lifting opener  28 , thereby reducing wear or damage that may be caused by such impediments. 
   A top view of the precision hoe opener assembly  10  is illustrated in  FIG. 3 . The figure shows cylinder  20 , first member  16 , second member  18 , shank adapter  24 , and rear frame  36 . The embodiment illustrates that pin  32  is used to couple and control movement of many components of opener assembly  10 , including first member  16 , rear frame  36 , and shank adapter  24 . The view also illustrates that packer wheel assembly  38  places packer wheel  40  directly behind the opener  28 . 
   Referring back to  FIG. 2 , the opener assembly  10  and opener  28  are depicted in a deployed position. During normal operation in a deployed position, opener  28  may break through terrain  52  creating a draft force on opener  28 . In this deployed position, a cylinder load is directed along the cylinder  20  and cylinder rod to shank adapter  24 , manipulating packer wheel  40  and opener  28  with a generally constant downward force. In particular, the geometry of the illustrated parallel linkage, including first member  16 , second member  18 , frame support  12 , and rear frame  12 , results in a generally constant downward force on opener  28  and packer wheel  40  as the terrain elevation fluctuates. 
   In general, the drawing illustrates that the precision opener assembly  10  has an increased range of motion providing a generally constant packing force to the soil. This is achieved in part by the opener assembly  10  maintaining a substantially constant angle between packer wheel assembly  38  and terrain  52 . In addition, the geometry of the hydraulically driven parallel linkage assembly, including elements  12 ,  16 ,  18 , and  20 , allows the opener assembly to maintain the substantially constant packing force and the substantially constant orientation with respect to the terrain. 
   As will be appreciated by those skilled in the art, the disclosed embodiments of precision opener  10  provide control of the packing force and the seeding depth by controlling opener  28  and packing wheel  40 . The opener  10  advantageously responds to variations in the terrain, draft force on the opener  28 , the packing force, or a combination thereof. Thus, the opener  10  can provide a generally uniform packing force and seeding depth to improve the overall quality of the seeding process, and in turn improve subsequent growth originating from the seeds. Again, the hoe opener  10  has a variety of adjustment mechanisms to control the location of the packer wheel  40 , the opener  28 , or a combination thereof. 
     FIG. 4  illustrates the agricultural implement assembly, including a plurality of precision opener assemblies  10 , as row units of a complete agricultural planter system  54 , as may be towed behind a tractor (not shown). 
   While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.