Patent Publication Number: US-7896095-B2

Title: Soil aerator

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of U.S. application Ser. No. 12/251,097 (now U.S. Pat. No. 7,717,188), filed Oct. 14, 2008 by Scott W. Bjorge et al. and entitled “Soil Aerator,” which is a continuation application of U.S. application Ser. No. 11/244,898 (now U.S. Pat. No. 7,451,831), filed Oct. 6, 2005 by Scott W. Bjorge et al. and entitled “Soil Aerator,” which is a continuation application of U.S. application Ser. No. 10/638,953 (now U.S. Pat. No. 7,055,617), filed Aug. 11, 2003 by Scott W. Bjorge et al. and entitled “Soil Aerator,” the entire disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     Soil aeration is a conventional technique used by groundskeepers to reduce compaction in the ground soil, stimulate plant growth, and promote proper drainage. Soils may become compacted from overuse or environmental effects, which ultimately affects the soil permeability and development of rooted plants within the soil. In particular, compacted soil restricts the amount of oxygen that can enter the soil and the amount of carbon dioxide that can escape. Not all grounds are affected equally by overuse and environmental factors. The amount of compaction depends soil texture, the amount of vegetation, and the moisture content of the soil. Periodic soil aeration relieves the compaction in the soil before the negative effects overburden the soil to the point that it can no longer support desirable vegetation. 
     In general, soil aerators have aeration tubes that penetrate the ground and remove “plugs” of soil. The aeration tubes are typically carried on bars or racks that are affixed to a rotary member. The rotor, racks, and associated gear hardware are typically large, bulky, and heavy. The overall dimensions and weight of the aeration device are accordingly increased. That, in turn, necessitates the use of relatively large tractors with large displacement engines. Consequently, most aeration devices are expensive to operate and ill-suited for residential, light commercial, or rental use. 
     SUMMARY 
     A soil aeration apparatus may include aeration tines that are actuated by a relatively compact gear system, which reduces the size and weight of the aeration apparatus. In an illustrative embodiment, a soil aeration apparatus includes at least two tine-holder shafts rotatably mounted to a carrier and aeration tines attached to each shaft. The apparatus may also include a gear system for rotating the tine-holder shafts while the tine-holder shafts revolve about a central axis of the carrier. The gear system may have a planetary gear coupled to each tine-holder shaft and a sun gear axially aligned with the central axis such that each sun gear engages a plurality of planetary gears. 
     In various embodiments, a soil aeration apparatus may operate without a centrally disposed support shaft, thus enabling the tine-holder shafts to be positioned closer to one another and reducing the size of the apparatus. In one illustrative embodiment, a soil aeration apparatus may include a carrier rotatably attached to a frame such that the carrier is rotatable about a central axis. The apparatus may also include first and second two tine-holder shafts rotatably mounted to the carrier and aeration tines attached to each shaft. A non-centrally located support shaft may be coupled to the carrier and offset from the central axis and mounted to the carrier. The first and second shafts may be offset from the central axis such that the tines are operative to move through the central axis without interference from another tine or shaft. 
     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a soil aeration apparatus in accordance with an embodiment of the invention. 
         FIG. 2  is a perspective view of a frame for housing the soil aeration apparatus of  FIG. 1 , with certain components of the frame removed. 
         FIG. 3  is a perspective view of a soil aeration apparatus in accordance with another embodiment of the invention. 
         FIG. 4  is a side view of the soil aeration apparatus of  FIG. 3 . 
         FIG. 5  is a perspective view of a frame for housing the soil aeration apparatus of  FIG. 4 , with a side panel removed from the frame. 
         FIG. 6  is a perspective view of the soil aeration apparatus of  FIG. 1  and the soil aeration apparatus of  FIG. 3 . 
         FIG. 7A-C  are side views of a soil aeration tine forming an aeration pocket in accordance with an embodiment of the invention. 
         FIG. 8  is a side view of the soil aeration apparatus of  FIG. 3  in accordance with another embodiment of the invention. 
         FIG. 9  is a side view of the soil aeration apparatus of  FIG. 3  in accordance with yet another embodiment of the invention. 
         FIG. 10  is a perspective view of an aeration tine that may be used with a soil aeration apparatus in accordance with an embodiment of the invention. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Referring to  FIG. 1 , a soil aeration apparatus  10  includes two tine-holder shafts  30  and  40  extending between opposing carriers  20  and  22 . The shafts  30  and  40  are rotatably mounted to the carriers  20  and  22  such that each shaft may rotate  68  about its own axis. The shafts  30  and  40  are positioned substantially parallel in the axial direction, and soil aeration tines  50  extend from each shaft  30  and  40  in the radial direction. The soil aeration tines  50  may penetrate and remove a portion of soil from a ground surface as is taught, for example, in U.S. Pat. No. 6,513,603 issued to Bjorge on Feb. 4, 2003, the contents of which are herein incorporation by reference. Two non-centrally located support shafts  24  and  26  also extend between the opposing carriers  20  and  22 . The support shafts  24  and  26  are fixedly mounted to the carriers  20  and  22  and provide mechanical support for the soil aeration apparatus  10  when in operation. A gear system  60  is engaged with the tine-holder shafts  30  and  40  to cause rotation of the tine-holder shafts  30  and  40 . The gear system  60  has a plurality of planetary gears  63  and  64  for each sun gear  65 . Each shaft  30  or  40  has a planetary gear  63  or  64  attached thereto. In this embodiment, the sun gear  65  is positioned between the planetary gears  63  and  64  and is engaged with the planetary gears  63  and  64  using a drive chain  66 . Because a plurality of planetary gears  63  and  64  are operated using an individual sun gear  65 , the bulkiness of the gear system  60  is advantageously reduced. Furthermore, because the apparatus  10  does not use a centrally located support shaft, the tine-holder shafts  30  and  40  may be positioned closer to one another, thus reducing the overall size of the apparatus  10 . 
     Referring to  FIG. 1  in more detail, bearings  32  and  42  may be used to rotatably mount the shafts  30  and  40 , respectively, to the carriers  20  and  22 . The bearings  32  and  42  may comprise ball bearings, roller bearings, or bushings, and may provide access for a portion of the shafts  30  and  40  to extend through the carriers  20  and  22 . The planetary gear  63  is axially aligned with the shaft  30  and fixedly mounted to the portion of the shaft  30  on the outer side of the carrier  20 . Similarly, the planetary gear  64  is axially aligned with the shaft  40  and mounted to the portion of the shaft extending through the carrier  20 . In this embodiment, the planetary gears  63  and  64  are radially aligned with the sun gear  65  such that a single drive chain  66  is engaged with all three gears  63 ,  64 , and  65 . Briefly describing the operation of the gear system  60 , the carriers  20  and  22  are motivated to rotate about a central axis  21  using a drive means (not shown in  FIG. 1 ). The sun gear  65  is axially aligned with the central axis  21  but remains substantially fixed with respect to the central axis as the carriers  20  and  22  rotate. When the carriers  20  and  22  rotate, the tine-holder shafts  30  and  40  are caused to revolve around the central axis  21 . Likewise, the planetary gears  63  and  64  also revolve around the central axis  21 . As such, the planetary gears  63  and  64  revolve about the sun gear  65  in a direction  28  as the drive chain  66  causes the planetary gears  63  and  64  to rotate in a direction  68 . The motion of revolving  28  the shaft  30  or  40  about the central axis  21  while rotating  68  the shaft  30  or  40  about its own axis causes the desired motion of the tines  50  to penetrate and remove a portion of soil from the ground surface. 
     Still referring to  FIG. 1 , the support shafts  24  and  26  are positioned between the carriers  20  and  22  and fixedly mounted to near the perimeter of each carrier  20  and  22 . Because the support shafts  24  and  26  are non-centrally located (e.g., offset from the central axis  21 ), tine-holder shafts  30  and  40  may be positioned closer to the central axis  21  without interference from the tines  50  hitting a centrally located shaft. Rather, the tine-holder shafts  30  and  40  may rotate in the direction  68  as the tines  50  pass through the central axis  21  without interference. The compact arrangement of shafts  30 ,  40 ,  24 , and  26  advantageously reduces the overall size of the soil aeration apparatus  10  in comparison to other apparatus that require the tine-holder shafts  30  and  40  to be spaced apart for clearance between the revolving tines  50  and a centrally located support shaft. 
     Referring to  FIG. 2 , the soil aeration apparatus  10  may be installed in a frame  12 . The frame  12  may have a safety panel  13  to prevent damage to the tine-holder shafts  30  and  40  from debris and to protect a user from the moving tines  50  and tine-holder shafts  30  and  40 . The frame  12  may also include side panels  14  to protect the gear system  60  from debris. In the embodiment shown in  FIG. 2 , one side panel  14  is removed to better show the soil aeration apparatus within the frame  12 . Optionally, the sun gear  65  may be attached to the side panel  14  (removed from the view show in  FIG. 2 ) to maintain the sun gear  65  in a substantially fixed relationship with respect to the central axis  21 . The carriers  20  and  22  may be rotatably attached to the side panels  14  or other part of the frame  12  such that the carriers  20  and  22  may rotate about the central axis  21  while the frame  12  remains substantially fixed with respect to the central axis  21 . A set of wheels (not shown in  FIG. 2 ) may be connected to the side panels  14  or other part of the frame  12 . Additionally, the frame may include other components that enable the frame  12  to be attached to a tractor or other vehicle. 
     Referring to  FIG. 3 , another embodiment of a soil aeration apparatus  110  includes four tine-holder shafts  130 ,  135 ,  140 , and  145  extending between two carriers  120  and  122 . Soil aeration tines  50  extend in a substantially radial direction from each shaft  130 ,  135 ,  140 , and  145  and are capable of penetrating and removing a portion of soil from the ground surface. The shafts  130 ,  135 ,  140 , and  145  extend substantially parallel to one another in the axial direction between the carriers  120  and  122 . The shafts  130 ,  135 ,  140 , and  145  are rotatably mounted to the carriers  120  and  122  using bearings  132 ,  137 ,  142 , and  147 , respectively. As such, each tine-holder shaft  130 ,  135 ,  140 , or  145  may rotate about its own axis in a direction  168  while all the shafts  130 ,  135 ,  140 , and  145  revolve in a direction  128  around a central axis  121 . The bearings  132 ,  137 ,  142 , and  147  may comprise ball bearings, roller bearings, or bushings, and may provide access for a portion of the shafts  130 ,  135 ,  140 , and  145  to extend through the carriers  120  and  122 . 
     Referring to  FIGS. 3 and 4 , the soil aeration apparatus  110  includes a gear system  160  having a plurality of planetary gears  163 ,  164  (or  173 ,  174 ) for each sun gear  165  (or  175 ). In this embodiment, planetary gears  163  and  164  interact with sun gear  165 . Planetary gear  163  is axially aligned with and fixedly mounted to tine-holder shaft  130 . Likewise, planetary gear  164  is axially aligned with and fixedly mounted to tine-holder shaft  140 . The sun gear  165  is axially aligned with the central axis  121  but remains substantially fixed with respect to the central axis  121  as the carriers  120  and  122  rotate about the central axis  121 . A drive chain  166  is engaged with the sun gear  165  and the corresponding planetary gears  163  and  164 , which causes the planetary gears  163  and  164  to rotate in the direction  168  as the planetary gears  163  and  164  revolve about the sun gear  165  in the direction  128 . This rotational  168  and revolving  128  motion of the planetary gears  163  and  164  causes the tine-holder shafts  130  and  140  to move in a desired path for penetrating and removing portions soil from the ground surface. Planetary gears  173  and  174  interact with sun gear  175  by way of a drive chain  176  in a manner similar to that of sun gear  165  and planetary gears  163  and  164 . The interaction of planetary gears  173  and  174  with the sun gear  175  causes the tine-holder shafts  135  and  145  to have a rotational  168  and revolving  128  motion similar to that of tine-holder shafts  130  and  140 . The gear system  160  provides the desired motion of the tine-holder shafts  130 ,  135 ,  140 , and  145  without using individual sun gear and planetary gear for each tine-holder shaft (e.g., four tine-holder shafts, four sun gears, and four planetary gears). Rather, the gear system  160  operates a plurality of planetary gears from each sun gear, which advantageously reduces the bulkiness of the gear system of the soil aeration apparatus. 
     Referring to  FIG. 5 , the soil aeration apparatus  110  may be installed in a frame  112  that transports the apparatus over a ground surface. The frame may include a safety panel  113  and side panels  114 , as previously described in connection with  FIG. 2 . In this embodiment, a side panel  114  is removed to better show the soil aeration apparatus  110  housed in the frame  112 . In addition, the frame may include wheels  116  and a connection means  117  so that the frame  112  may be attached to a tractor or other vehicle and moved over the ground surface. 
     Briefly referring again to  FIG. 3 , the soil aeration apparatus  110  may include a support shaft  124  along the central axis  121 . This support shaft  124  provides mechanical stability for the soil aeration apparatus  110  when in operation. Optionally, the soil aeration apparatus  110  may operate without a centrally located support shaft  124 . For example, the tine-holder shafts  130 ,  135 ,  140 , and  145  may be rotatably mounted to the carriers  120  and  122  so as to provide sufficient mechanical stability for the soil aeration apparatus  110  without the need for the support shaft  124 . In such a case, the tine-holder shafts  130 ,  135 ,  140 , and  145  would also serve as non-centrally located support shafts. 
     Referring now to  FIG. 6 , the size of the soil aeration apparatus may be advantageously reduced by eliminating the centrally located support shaft. The soil aeration apparatus  10  (also shown in  FIG. 1 ) includes non-centrally located support shafts  24  and  26 . As such, the tine-holder shafts  30  and  40  may be positioned closer to the central axis  21  without the need for clearance space for the tines  50 . The tines  50  on one shaft  30  may be staggered from tines  50  on another shaft  40  such that the tines  50  may revolve about the tine-holder shaft  30  without interference from other tines  50 . In certain embodiments, there may be a need for mechanical support from a centrally located support shaft  124 . In such cases, the tine-holder shafts may be sufficiently spaced apart such that the tines  50  may revolve about one tine-holder shaft without interference from a centrally located support shaft or a neighboring tine-holder shaft. For example, the soil aeration apparatus  110  (also shown in  FIG. 3 ) includes a centrally located support shaft  124  and tine-holder shafts  130 ,  135 ,  140 , and  145  that are spaced apart to provide clearance for the tines  50 . The size of the soil aeration apparatus  110  may be reduced, however, if the centrally located support shaft  124  is eliminated and the tine-holder shafts are positioned closer to one another. 
     In operation, the soil aeration apparatus  10  or  110  may be attached to a frame  12  or  112  that guides the apparatus  10  or  110  over a ground surface. In some embodiments, the frame may be attachable to a tractor or other vehicle such that the apparatus is towed behind the vehicle over a ground surface. In other embodiments, the frame is configured to be manually pushed by a user over the ground surface. A drive means, such as a spinning drive shaft that causes the carriers to rotate, may be attached to the frame  12  or  112  and the soil aeration apparatus  10  or  110  to produce the desired revolving and rotation motion of the planetary gears and the tine-holder shafts. Alternatively, the drive means may comprise the carrier  20  or  120  being forced to rotate as it rolls along the ground surface. 
     Referring to  FIGS. 7A-C , the soil aeration tines  50  may operate to penetrate a ground surface  80  and remove a portion of soil  82 . The interaction of the gear system  60  and the tine-holder shafts  30  and  40  causes the revolving  28  and rotation  68  motions of the tine-holder shafts  30  and  40 , which in turn, causes the desired motion of the individual tines  50 . Notably, the direction of rotation  68  and the direction revolution  28  may be different from that depicted in  FIGS. 7A-C , depending on a number of factors, such as the type of aeration tine  50  used with the soil aeration apparatus  10 . (The operation of the soil aeration tines  50  is described with respect to the embodiment of the soil aeration apparatus  10  and gear system  60  of  FIG. 1 , but it is understood that the description also applies to other embodiments of the soil aeration apparatus, such as the embodiment shown in  FIG. 3 .) The gear system  60  is configured to orient the tine  50  at an acute angle to the ground surface  80  when the tine-holder shaft  30  is revolved  28  around the center axis  21  to a point near the ground surface  80 . 
     Referring to  FIG. 7A , the soil aeration tine  50  penetrates a patch of soil  82  at an acute angle  84  with respect to the ground surface  80 . In this embodiment, one or more soil fracturing surfaces  52  on the tine  50  penetrate the soil at an acute angle, which causes the soil proximate the aeration tine  50  to fracture upward rather than compact. Referring to  FIG. 7B , even though the tine-holder shaft  30  continues to revolve  28  around the central axis  21 , the soil aeration tine  50  is rotated  68  by the motion of the planetary gear  63  attached to the tine-holder shaft  30 . The sweeping action  56  from the revolving  28  and rotational  68  motions forms an aeration pocket  86  in the region penetrated by the soil aeration tine  50 . As shown in  FIG. 7C , the tine-holder shaft  30  continues to revolve  28  around the central axis  21 , which causes the tine  50  to be pulled from the soil  82  even as the tine  50  continues to rotate  68 . The removal action  58  from the revolving  28  and rotational  68  motions completes the formation of the aeration pocket  86 . In this embodiment, the tine  50  includes a cutting tube  55  that cuts and removes a plug  88  of soil  82  during the sweeping  56  and removal  58  actions. The penetration  54 , sweeping  56 , and removal  58  actions are repeated as the subsequent tine-holder shaft  40  is revolved  28  near the ground surface  80  and the corresponding planetary gear  64  causes the tines  50  to be oriented at an acute angle to the ground surface  80 . 
     Various embodiments of the gear system for the soil aeration apparatus  110  may be used to advantageously reduce the bulkiness of the apparatus  110 . Referring to  FIG. 8 , a gear system  260  may be implemented to cause the desired motion of the tine-holder shafts  130 ,  135 ,  140 , and  145 . In this embodiment, sun gear  265  is aligned with the central axis  121  and remains substantially fixed with respect to the central axis  121  even as the carrier  120  rotates about the central axis  121 . The sun gear  265  is not necessarily positioned between the planetary gears  263  and  264 , yet the gears  263 ,  264 , and  265  are radially aligned so that the drive chain  266  may engage the gears  263 ,  264 , and  265 . Similarly, planetary gears  273  and  274  interact with another sun gear (positioned behind the first sun gear  265  and not shown in  FIG. 8 ) that is axially aligned with the central axis  121 . Alternatively, the drive chains  266  and  276  may engage the same sun gear  265 , depending on the axial thickness of the sun gear  265  and the type of drive chain. As shown in  FIG. 8 , while the planetary gears  263 ,  264 ,  273 , and  274  move around the corresponding sun gears in the direction of revolution  128 , each planetary gear  263 ,  264 ,  273 , or  274  is caused to rotate about its own axis in the direction of rotation  168 . Because each sun gear is used to operate a plurality of planetary gears (rather than a one-to-one correspondence), the bulkiness of the soil aeration apparatus and gear system may be reduced. 
     In another embodiment, the gear system may include planetary gears that are indirectly engaged with a sun gear. Referring to  FIG. 9 , a drive chain  366  engages a first planetary gear  362  and a sun gear  365 . A secondary drive chain  376  is engaged with the first planetary gear  362  and other planetary gears  361 ,  363 , and  364 , but not with the sun gear  365 . The sun gear is axially aligned with the central axis  121  and remains substantially fixed with respect to the central axis  121  even as the carrier  120  rotates about the central axis  121 . When the carrier  120  rotates about the central axis  121 , the planetary gears  361 ,  362 ,  363 , and  364  revolve around the sun gear  365  in the direction  128 . The drive chain  366  causes the planetary gear  363  to rotate about its own axis in the direction  168 . This rotation of planetary gear  362  causes the drive chain  376  to rotate the other planetary gears  361 ,  363 , and  364  in the same rotational direction  168 . As such, the more compact gear system  360  drives four planetary gears  361 ,  362 ,  363 , and  364  using an individual sun gear  365 . 
     Certain embodiments described above show a gear system positioned on the one side of the soil aeration apparatus. Other embodiments, however, may include two gear systems—one gear system positioned on each side of the apparatus. For example, one gear system may be positioned on the outer side of one carrier  20  or  120 , and a second gear system (substantially mirrored to the first gear system) may be positioned on the outer side of the opposing carrier  22  or  122 . 
     In addition, the soil aeration tines  50  are not limited to the embodiment shown in  FIGS. 7A-C . Rather, the tines  50  may various configurations, such as fracturing surfaces, spikes, aeration tubes, aeration blades, or a combination thereof, depending on the soil texture or other factors. Referring to  FIG. 10 , for example, the tines may include aeration blades  150  that penetrate and cut the soil without necessarily removing a “plug” of soil from the ground. The aeration blade may include a tip  152 , a concave edge  154 , and a convex edge  156  to penetrate and cut the soil while reducing the amount of soil compaction. As such, the ground surface is not littered with plugs of soil after operation of the soil aeration apparatus. 
     Furthermore, the direction of rotation  68  or  168  and the direction of revolution  28  or  128  are not limited to the embodiments shown in  FIGS. 1 ,  3 ,  4 ,  7 A-C,  8 , and  9 . For example, the tines  50  that comprise soil aeration blades may be operated with the direction of rotation  68  or  168  and/or the direction of revolution  28  or  128  being reversed from what is shown. 
     Further yet, the gear system may use an engaging member other than a drive chain to engage the gears in the gear system. For example, the engaging member may comprise a cable, belt, linked chain, or the like. Accordingly, the contact surface of the gears may be configured to appropriately engage the selected type of engaging member. 
     Moreover, the gear system of the soil aeration apparatus may have any number of sun gears, and is not limited to embodiments having one or two sun gears. Accordingly, the gear system may include any number of planetary gears such that each sun gear engages a plurality of planetary gears. 
     In another embodiment, the soil aeration apparatus may have a non-centrally located support shaft that is positioned concentrically with a tine-holder shaft. In such an embodiment, the tine-holder shaft may be rotatably mounted to the carrier and coupled to a planetary gear while an inner support shaft is fixedly coupled with respect to the opposing carriers. This arrangement of the tine-holder shaft and the non-centrally located support shaft provides support for the soil aeration apparatus. Moreover, because the support shaft is not occupying space outside of the tine-holder shaft, an increased number of tine-holder shafts may be mounted to the carriers. Alternatively, the non-centrally located support shafts may be mounted to the carriers along the outer perimeter of the carriers. For example, in the embodiments where the carriers are circular, the support shafts may be very thin members having a concave surface that matches the curve of the carrier&#39;s circumference. This concave surface may be mounted to the carrier along a portion of the circumference such that the non-centrally located support shaft does not occupy a significant amount of area on the opposing faces of the carriers. 
     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.