Abstract:
A vehicle seat assembly includes an anti-backlash mechanism in the seat adjustment gearing to reduce or eliminate gaps that cause looseness in the gearing.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to devices, systems, and processes useful as vehicle seat assemblies, and more specifically to anti-backlash mechanisms in the seat adjustment drive mechanisms of such vehicle seat assemblies. 
   2. Brief Description of the Related Art 
   Anti-backlash gear mechanisms are well known in the art to provide a useful way of reducing or eliminating gaps between the teeth of driving and driven gears. By way of example, several U.S. patents describe such anti-backlash mechanisms, including U.S. Pat. Nos.: 1,748,820, 2,092,888, 2,310,232, 2,311,902, 2,607,238, 3,365,973, 5,056,613, and 6,293,166. 
   A problem in current vehicle seating design is that, while seat assemblies are being constructed to be more adjustable in numerous ways, and those adjustment mechanisms are often driven by drive motors, looseness in the adjustment mechanism can arise. Regardless of the source of this looseness, e.g., by too large a manufacturing tolerance of the component pieces or wear of the interacting parts, looseness can be perceived by the vehicle user as a fault in the mechanism, and in general is preferable to avoid. 
   Currently, vehicle seat adjustment mechanisms often employ simple gear reductions or worm-gear mechanisms to transform the rotation of a high RPM, low torque drive motor of the seat assembly into a desired recliner, height, and/or slide motion of the power seat. Typically, tolerances are kept very tight to reduce initial looseness; however, that initial looseness is invariably present, and can become more pronounced as the assemblies components wear. 
   There thus remains a need in vehicle seating assemblies to reduce or eliminate gaps in the gearing of the adjustment mechanisms of the seat assemblies, and thereby reduce or eliminate looseness in these adjustment mechanisms. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the invention, a vehicle seat assembly comprises a seat portion against which a user of the seat can be positioned, and an anti-backlash gear mechanism attached to the seat portion, the anti-backlash gear mechanism including a first gear having first gear teeth, the first gear attached to the seat portion, a second gear substantially similar to the first gear and having second gear teeth, at least one spring attaching the first gear to the second gear such that the first gear teeth and the second gear teeth are adjacent to and offset from each other, and a third gear having third gear teeth mating with said first teeth and said second teeth, wherein the at least one spring biases the second gear teeth against the third gear teeth. 
   According to another aspect of the present invention, a vehicle comprises at least one of these vehicle seat assemblies. 
   Still other aspects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of embodiments constructed in accordance therewith, taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a perspective view of an anti-backlash mechanism in accordance with the present invention; 
       FIG. 2  illustrates an enlarged view of portions of an anti-backlash mechanism of the present invention interacting with a drive pinion; 
       FIG. 3  illustrates an exploded perspective view, with portions shown in phantom, of the mechanism of  FIG. 1 ; 
       FIG. 4  illustrates portions of a vehicle seat assembly incorporating an anti-backlash mechanism of the present invention; and 
       FIG. 5  illustrates a highly simplified view of a vehicle including vehicle seat assemblies in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     FIG. 1  illustrates a perspective view of an exemplary embodiment of an anti-backlash mechanism  10  in accordance with principles of the present invention. The mechanism  10  includes a first gear  12  and second gear  14  which is substantially the same as and mounted next to the first gear. The gear  12  is mounted to a drive shaft  16  which, when rotated, rotates the gear  12 . The first  12  and second  14  gears are attached to each other by springs  18 ,  20 , described in greater detail below. 
     FIG. 2  illustrates an enlarged view of portions of an anti-backlash mechanism  10  of the present invention, interacting with a drive pinion  30 . The gears  12 ,  14  have teeth  22 ,  24 , respectively, which are driven by the teeth  32  of the pinion  30 . Because the second gear  14  is connected to the gear  12  via springs  18 ,  20 , and the springs bias the first and second gears  12 ,  14  in a circumferential direction, gaps between the teeth  22 ,  32 , are bridged by the teeth  24  of the second gear  14 , thus reducing or eliminating looseness between the driving ( 30 ) and driven ( 12 ) gears. Of course, an anti-backlash mechanism in accordance with the present invention can instead be incorporated in the drive gear as well as, or instead of, in the driven gear. 
     FIG. 3  illustrates an exploded perspective view, with portions shown in phantom, of the mechanism  10  of  FIG. 1  when driven by a shaft  16  rather than a pinion  30 . The springs  18 ,  20  are mounted on pins  34 ,  38  and  36 ,  40 , respectively, and thus bias the gears  12 ,  14  in a known manner. The first gear  12  includes a hole  50  through which the shaft  16  passes, while the second gear  14  includes a similar hole  48  through which the shaft can pass without interfering with the rotation of the second gear  14 . The shaft is mounted to rotate and drive the first gear  12 , e.g., by including a plate  44 , secured to the shaft, through which bolts  42  pass and fixedly attach the plate to holes  46  in the first gear  12 . The present invention is not limited to this particular embodiment of structures which attach a drive shaft to the first gear  12 , and other mechanisms are within the scope of the present invention. As well known to those of skill in the art, the spring loaded connection of the gears  12 ,  14 , resists backlash by taking up slack between the gear  12  and the pinion  30 , which can be present because of manufacturing tolerances and wear on the teeth  22 ,  32 . 
     FIG. 4  illustrates portions of a vehicle seat assembly  60  incorporating an anti-backlash mechanism  10  of the present invention. The seat assembly  60  includes a seat bottom  62 ; other portions of the seat against which a user of the seat can be positioned, such as the seat back (see  FIG. 5 ) are not illustrated so as to not obscure aspects of the present invention. The seat bottom  62  is mounted to the vehicle at mounting brackets  64 , which may be stationary or themselves mounted to displace forward and backward, in well know manners. One or more links  66  connect the brackets  64  to one or more front sector gear assemblies  70 , which are movably mounted to the seat bottom, while one or more rear section gear assemblies  68  extend between a pivot point  82  on the bracket  64  and a pivot point  80  at the seat bottom  62 . 
   In the exemplary embodiment illustrated in  FIG. 4 , each of the sector gear assemblies  68 ,  70 , include gear teeth  84 ,  86 , which mate with correspondingly configured teeth (not labelled; see  FIG. 2 ) of drive pinions  74 ,  72 , respectively. The drive pinions  72 ,  74 , are rotatably driven by a one or a pair of controllable motors  76 ,  78 , illustrated in simplified form. Furthermore, in this embodiment, the forward sector gear assembly  70  includes a pivot point  79  around which the gear assembly  70  can rotate. Alternatively, instead of a pinion drive, the sector gear assemblies  68 ,  70  can be attached to and driven by a driveshaft, as described above with reference to  FIGS. 1 ,  3 , e.g., attached to at the pivot points  79 ,  80 , while the pinions  72 ,  74  are attached to the seat bottom  62 . The seat bottom  62  is movably attached to and supported on each sector gear assembly  68 ,  70 , via pins  90 ,  92 , sliding in slots  94 ,  96  formed in the gear assemblies. 
   One or both of the sector gear assemblies  68 ,  70  include first and second gears, connected together by springs mounted on pins, as described above. Alternatively and in more general terms, one or both of the sector gear assemblies  68 ,  70  include anti-backlash mechanisms as described herein, or alternatively as known to those of ordinary skill in the art, e.g., those described in the aforementioned U.S. patents. 
     FIG. 5  illustrates a highly simplified view of a vehicle  100  including vehicle seat assemblies  60  in accordance with the present invention. The vehicle  100  can be any known vehicle, including, but not limited to: automobiles; trains; airplanes; boats; and any other vehicle which has a seat. 
   With continued reference to  FIG. 4 , operation of the seat assembly  60  will be described. As previously established, there often in a gap or play between a drive gear and a driven gear in vehicle seat assemblies, such as assembly  60 , and more particularly between pinions  72 ,  74 , and the sector gear assemblies  68 ,  70 , as a result of manufacturing tolerances and/or gear tooth wear. Thus, when the pinions  72 ,  74  rotate, rotating the assemblies  68 ,  70  about their respective rotation points  80 ,  79 , the respective portions of the seat bottom  62  are raised (or lowered, depending on the drive direction) as the pins  90 ,  92  ride in the slots  94 ,  96  of the sector gear assemblies. During this process, the springs  18 ,  20  (see  FIGS. 1-3 ) urge the second gear  20  to maintain contact with the drive gear, thus reducing or even eliminating the gap between the drive and driven gears. 
   The present invention is not limited to the particular embodiment described above, that is, incorporated into the mechanism which selectively raises and lowers a vehicle seat. More particularly, the present invention also extends to application to manual or power adjustment of any vehicle seat position, including recline position, height, and/or sliding motion of a power or manual vehicle seat. 
   While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.