Abstract:
A rotary adjustment mechanism is provided. The rotary adjustment mechanism has a first member, a second member, a first gear, a second gear, a locking gear, a spring, and a release. The first gear is rotationally attached to the first member. The second member is pivotally attached to the first member. The second gear is rotationally attached to the second member. The locking gear is moveable from a first position coupling the first gear with the second gear to a second position decoupling the first gear with the second gear. The spring biases the locking gear towards the first position. The release is coupled to the locking gear and selectively moves the locking gear to the second position.

Description:
TECHNICAL FIELD  
       [0001]    This invention relates generally to a rotary adjustment mechanism, and more particularly, to a rotary adjustment mechanism for a seat. 
       BACKGROUND  
       [0002]    Machines such as skid steer loaders, multi terrain loaders, backhoe loaders, agricultural tractors, track-type tractors, articulated trucks, wheel loaders, automobiles, on-highway trucks, and other vehicles typically have an adjustable seat. This adjustable seat typically uses a rotary adjustment mechanism to rotate one seat element with respect to another. A rotary adjustment mechanism in such a seat may include, for example, an eccentric coupled with a ring and a spur gear. However, such a design requires that the eccentric be turned several times through a large angle with respect to the seat, resulting in considerable effort to the user. 
         [0003]    Another example of a rotary adjustment mechanism is disclosed in U.S. Pat. No. 5,689,999 to Wiley (“Wiley”). Wiley discloses an apparatus having two members that are relatively rotatable about an axis, with one member having a plurality of arcuately shaped locking pins that are moveable between retracted and projected positions. The other member has a plurality of arcuately shaped sockets sized to hold the projections. The arcuate spacing between adjacent pins and sockets is uniform, while the spacing between the pins differs from that between the sockets. 
         [0004]    While both Wiley and the mechanisms having eccentrics provide a rotary adjustment mechanism, such designs are typically mounted at the side of the seat along a pivot axis, and actuated by a lever or knob that is pivotal about the pivot axis. This actuation may require additional space that may not be available in applications having limited clearance about the pivot axis and may not be suitable for applications requiring remote actuation. 
         [0005]    The present invention is directed to overcome one or more of the problems as set forth above. 
       SUMMARY OF THE INVENTION  
       [0006]    In one aspect of the present invention, a rotary adjustment mechanism is provided. The rotary adjustment mechanismseat has a first member, a second member, a first gear, a second gear, a locking gear, a spring, and a release. The first gear is rotationally attached to the first member. The second member is pivotally attached to the first member. The second gear is rotationally attached to the second member. The locking gear is moveable from a first position coupling the first gear with the second gear to a second position decoupling the first gear with the second gear. The spring biases the locking gear towards the first position. The release is coupled to the locking gear and selectively moves the locking gear to the second position. 
         [0007]    In another aspect of the present invention, a seat is provided. The seat has a base, a seat back, a first gear, a second gear, a locking gear, a spring, and a release. The first gear is rotationally attached to the base. The seat back is pivotally attached to the base. The second gear is rotationally attached to the seat back. The locking gear is moveable from a first position coupling the first gear with the second gear to a second position decoupling the first gear with the second gear. The spring biases the locking gear towards the first position. The release is coupled to the locking gear and selectively moves the locking gear to the second position. 
         [0008]    A third aspect of the present invention includes a method of providing a seat. The method includes the steps of providing a first member and rotationally attaching a first gear to the first member. The method also includes the step of pivotally attaching a second member to the first member. The method also includes the step of rotationally attaching a second gear to the second member. The method also includes the step of providing a locking gear that is moveable from a first position coupling the first gear with the second gear to a second position decoupling the first gear with the second gear. The method also includes the steps of biasing the locking gear towards the first position and coupling a release to the locking gear that selectively moves the locking gear to the second position. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]      FIG. 1  is a perspective view of a seat suitable for use with the present invention. 
           [0010]      FIG. 2  is a detail perspective view of the seat of  FIG. 1 , with the seat pan and the seat back shown in phantom, illustrating a first and second embodiment of the rotary adjustment mechanism of the present invention. 
           [0011]      FIG. 3  is a perspective view showing the bottom of the seat pan and the first embodiment of the rotary adjustment mechanism. 
           [0012]      FIG. 4  is an exploded perspective view of the rotary adjustment mechanism of  FIG. 3 . 
           [0013]      FIG. 5  is a cross section view of the rotary adjustment mechanism of  FIG. 3 . 
           [0014]      FIG. 6  is a rear perspective view of the seat of  FIG. 1 , illustrating the seat back and the second embodiment of the rotary adjustment mechanism. 
           [0015]      FIG. 7  is an exploded perspective view of the second embodiment of the rotary adjustment mechanism of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION  
       [0016]    A seat  10  in accordance with the present invention is illustrated in  FIG. 1 . As shown, the seat  10  includes a seat back  12 , a head rest  14 , a seat pan  16 , a suspension system  22 , a lumbar adjustment  24 , a base  26 , and levers  30 ,  32 ,  34 . The seat  10  may be mounted to a floor  40  in an operator compartment of a machine (not shown). The suspension system  22  damps and absorbs vibrations and shocks from the machine to an occupant of the seat  10 . An adjustment knob (not shown) may adjust the spring rate of the suspension system  22 . The lever  32  may allow the seat  10  to slide fore and aft along the base  26  with respect to the floor  40 . The seat may also include a seat-height adjustment mechanism (not shown). Alternately, the seat  10  may be fixedly mounted to the floor  40 , such that the seat  30  does not move with respect to the floor  40  in either a forward direction or a transverse direction. The seat  10  may incorporate a seat belt  18  and a seat belt latch  20  to secure an operator in the seat  10 , and an operator presence switch (not shown) that engages or disengages the transmission, parking brake, or engine depending on whether an operator is sitting in seat  10  or not. 
         [0017]    As seen in  FIG. 2 , the seat  10  includes a seat pan tilt mechanism  100  and a seat back recline mechanism  200 . The seat pan tilt mechanism  100  includes a rotary adjustment mechanism  101  that is released by the release lever  34  and allows the seat pan  16  to pivot about an axis  102  with respect to the base  26 . As seen in  FIG. 3 , an alignment rod  104  extends axially along the axis  102  and is axially and rotatably secured to the seat pan  16  via seat pan mounting brackets  160 . The alignment rod  104  is also rotatably secured and supported by the base  26  via bearings  164  (seen in  FIG. 2 ) located within seat base mounting brackets  162 . Referring now to  FIGS. 4-5 , the rotary adjustment mechanism  101  includes a fixed slider  106 , a rotating slider  110 , a first spring  116 , a first outer gear  120 , a second outer gear  130 , a locking or inner gear  140 , and a second spring  150  arranged axially along the alignment rod  104 . 
         [0018]    Best seen in  FIGS. 4-5 , the fixed slider  106  is mounted along the alignment rod  104  and adjacent to an axial stop  105  that prevents the fixed slider  106  from sliding along the alignment rod  104 . The fixed slider  106  also includes a projection  107 . The projection  107  fits within a slot or groove (not shown) in the base  26  to prevent the fixed slider  106  from rotating about the axis  102  and the alignment rod  104 . The fixed slider  106  also includes a spiraled ramp  108 . 
         [0019]    The rotating slider  110  is mounted adjacent the fixed slider  106  along the alignment rod  104 . The rotating slider  110  has a spiraled ramp  112  that slidably engages the spiraled ramp  108  of the fixed slider  106 . The rotating slider also has an axial projection  114  extending along the alignment rod  104 . A cable  170  extends from the release lever  34  and is secured to the rotating slider  110 . One or both of the fixed and rotating slider  106 ,  110  may be injection molded from a low friction plastic, such as polytetrafluoroethylene, although other materials such as nylon, acetal, or other plastics or metals may also be used with sufficient lubrication. 
         [0020]    The first outer gear  120  is mounted adjacent to the rotating slider  110  and coaxial with the alignment rod  104 . The second outer gear  130  is mounted adjacent to the first outer gear  120  along the alignment rod  104 . At least one of the seat pan mounting brackets  160  may be integrally formed with the second outer gear  130 , axially and rotatably securing the second outer gear  130  to the alignment rod  104 . Both the first outer gear  120  and the second outer gear  130  may have an internal bore  122 ,  132 , with each bore  122 ,  132  having axial splines  134 . The first outer gear  120  may also include a circumferential groove  126  mounted along the face  127  distal from the second outer gear  130 . 
         [0021]    As seen in  FIG. 5 , the inner gear  140  is slidably mounted along the alignment rod  104 . The first outer gear  120  is slidably mounted on a first section  142  of the inner gear  140 . The first section  142  of the inner gear  140  is also axial engaged by the axial projection  114  of the rotating slider  110 . A second section  144  of the inner gear  140  has a plurality of external axial splines  146  that are operably coupled with the splines  134  of the first and second outer gears  120 ,  130 . The first and second outer gears  120 ,  130  and the inner gear  140  may be made from a powder metallurgy forging process or any other technique known in the art.  FIG. 5  illustrates the first and second outer gears  120 ,  130  as having ring gear portions, with the inner gear  140  having a mating spur gear. However, other configurations may also be used, such that the inner or locking gear  140  may be formed as a ring gear, with the first and second outer gears  120 ,  130  having spur gear portions. 
         [0022]    One end of the first spring  116  is positioned in the circumferential groove  126  of the first outer gear  120  and biases the rotating slider  110  away from the first outer gear  120 , so that the rotating slider  110  slides along the spiraled ramp  108  of the fixed slider  106  and the axial projection  114  disengages from the first section  142  of the inner gear  140 . One end of the second spring  150  biases the inner gear  140  away from the second outer gear  130 , such that the inner gear  140  is operably coupled with both the first outer gear  120  and the second outer gear  130 . While  FIG. 5  depicts first and second spring  116 ,  150  as wave springs, other types, quantities, or configurations of springs may also be used. 
         [0023]    Referring now to FIGS.  2  and  6 - 7 , the seat back recline mechanism  200  includes a rotary adjustment mechanism  201  arranged along an axis  202 . The rotary adjustment mechanism  201  is released by the release lever  30  and allows the seat back  12  to rotate about an axis  203  with respect to the base  26 . The seat back  12  is coupled to the rotary adjustment mechanism  201  through a transmission  280  including a first recline gear  282  secured to the rotary adjustment mechanism  201  and a second recline gear  284  secured to the seat back  12 . 
         [0024]    Similar to the rotary adjustment mechanism  101  described above, the rotary adjustment mechanism  201  includes a fixed slider  206 , a rotating slider  210 , a first spring  216 , a first outer gear  220 , a second outer gear  230 , an inner gear  240 , and a second spring  250  arranged axially along an alignment rod  204 . In addition, the rotary adjustment mechanism  201  also includes a torsion spring  272  and a rotary stop  274 . The torsion spring  272  is rotatably secured to the alignment rod  204  and to the base  26 , biasing the alignment rod  204  with respect to the base  26 . The second outer gear  230  is axially secured to the rod  204 , with the first outer gear  220  being rotatably secured to the base  26  through a slot and groove configuration. The alignment rod  204  is axially and rotatably secured to the first recline gear  282 . The alignment rod  204  is also rotatably secured and supported by the base  26  via bearings  264  located within recline mounting brackets  262 . Other details of the rotary adjustment mechanism  201  are similar to those described above and illustrated in  FIGS. 2-5  for the rotary adjustment mechanism  101 . 
       INDUSTRIAL APPLICABILITY  
       [0025]    In operation, an operator pulls upwards on release lever  34  to adjust the angle of the seat pan  16  with respect to the base  26 . This pulling motion causes the release lever  34  to pivot about a lever pivot axis  38  and pull the cable  170 . This pull on cable  170  causes the rotating slide  110  to rotatably slide up along the ramp  108  of the fixed slide  106 , translating laterally along the alignment rod  104 . This lateral translation compresses the first spring  116  and causes the axial projection  114  to laterally push the locking or inner gear  140  from a locked position along the alignment rod  104  to an unlocked position. As the inner gear  140  slides along the alignment rod  104 , the splines  146  of the inner gear  140  disengage from the splines (not shown) of the first outer gear  120  and decouple the first outer gear  120  from the second outer gear  130 . When the inner gear  140  disengages from the first outer gear  120 , the rotary adjustment mechanism  101  is unlocked and allows for relative rotation between the gear  120  and the gear  130 , which in turn allows the seat pan  16  to rotate about the pivot axis  102  with respect to the base  26 . The number of splines  134 ,  146  on the gears  120 ,  130 ,  140  determines the angular resolution of the rotary adjustment mechanism  101 —more splines  134 ,  146  may allow for finer adjustments, while fewer splines  134 ,  146  may allow for more coarse adjustments. 
         [0026]    After the user has set the desired seat pan tilt, the user releases the release lever  34 . This releases the tension on the cable  170 , causing the first spring  116  to bias the rotating slide  110  to rotatably slide down along the ramp  108  of the fixed slide  106 . This disengages the axial projection  116  from the inner gear  140 , and allows the second spring  150  to bias the inner gear  140  from the unlocked or decoupled position into a locked or coupled position, pushing the inner gear  140  back into engagement with both the first outer gear  120  and the second outer gear  130 . 
         [0027]    Similar to the operation of the seat pan adjustment described above, an operator pulls upwards on release lever  30  to adjust the angle of the seat back  12  with respect to the base  26 . This pulling motion causes the release lever  30  to pivot about a lever pivot axis  38  and pull a cable  270 . This pull on the cable  270  causes the rotating slide  210  to rotatably slide up along the ramp  208  of the fixed slide  206 , translating laterally along the alignment rod  204 . This lateral translation compresses the first spring  216  and causes the locking or inner gear  240  to move from a locked position and slide along the alignment rod  204  and decouple the first outer gear  220  from the second outer gear  230  to an unlocked position. This unlocks the rotary adjustment mechanism  201  and allows for relative rotation between the gear  220  and the gear  230 , allowing the seat back  12  to rotate about the pivot axis  203  with respect to the base  26 . As the seat back  12  rotates about the pivot axis  203 , the transmission  280  transmits the rotary motion about the pivot axis  203  to the alignment rod  204  through the recline gears  282 ,  284 . As the alignment rod  204  is rotated, the torsion spring  272  biases the alignment rod  204 , such that the seat back  12  is biased towards the seat pan  16  about the pivot axis  203 . The rotary stop  274  prevents the seat back  12  from rotating too far forward or back about the pivot axis  203 . 
         [0028]    Releasing the lever  30  releases the tension on the cable  270 , causing the first spring  216  to bias the rotating slide  210  to rotatably slide down along the ramp  208  of the fixed slide  206 . This disengages the axial projection  216  from the inner gear  240 , and allows the second spring  250  to bias the inner gear  240  from the unlocked or decoupled position into a locked or coupled position, pushing the inner gear  240  back into engagement with both the first outer gear  220  and the second outer gear  230 . Other details of the rotary adjustment mechanism  201  are similar to those described above and illustrated in  FIGS. 2-5  for the rotary adjustment mechanism  101 . 
         [0029]    Several advantages over the prior art may be associated with the rotary adjustment mechanism  101 ,  201 . For example, the configuration of the rotary adjustment mechanism  101 ,  201  allows for a compact design. In addition, the design also allows the rotary adjustment mechanism  101 ,  201  to be actuated from the front of the seat. However, space permitting, the rotary adjustment mechanism  101 ,  201  may also be actuated from the side. 
         [0030]    Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure, and the appended claims.