Abstract:
A seat apparatus for a vehicle includes supporting member and a moving member whose position is adjustable relative to the supporting member while a posture of the moving member is in a predetermined posture comprising a link member rotatably connected to the supporting member and the moving member respectively, a first gear secured to the moving member, a second gear secured to the supporting member and a transmitting gear rotatably supported to the link member. The transmitting gear includes a first partial gear meshing with the first gear and a second partial gear meshing with the second gear.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2003-198001, filed on Jul. 16, 2003, the entire content of which is incorporated herein by reference. 
   FIELD OF THE INVENTION 
   This invention generally relates to a seat apparatus including a link mechanism for changing a position of a part of the seat or folding a part of the seat, for example, a seat cushion, a leg portion, a footrest or a seat back. More particularly, the present invention pertains to a seat apparatus including a link mechanism for sufficiently changing the position of the part. 
   BACKGROUND 
   As an example of a device for sufficiently changing a position of a predetermined part of the seat, a known seat apparatus is disclosed in U.S. Pat. No. 6,095,610. The disclosed seat apparatus includes a link mechanism for changing a position of a footrest relative to the seat cushion. Such link mechanism basically includes a known four joint linkage having four links provided in a rectangle and rotation shafts for connecting the links. The four joint linkage applied to the part which is sufficiently changed also includes plural auxiliary links for securing the strength of the link mechanism enough to support a load applied to the footrest even if an angle between the links becomes equal to or more than a predetermined angle. 
   A structure of the link mechanism having aforementioned configuration is complicated because many links and rotation shafts connecting the links are provided thereto. In addition, relatively large and heavy links and rotation shafts need to be provided to such link mechanism applied to a vehicle seat apparatus to secure enough strength for supporting excessive load applied to the seat. 
   A need exists for a seat apparatus to include a link mechanism being light in weight and having few links. 
   SUMMARY OF THE INVENTION 
   According to an aspect of the present invention, A seat apparatus for a vehicle includes supporting member and a moving member whose position is adjustable relative to the supporting member while a posture of the moving member is in a predetermined posture comprising a link member rotatably connected to the supporting member and the moving member respectively, a first gear secured to the moving member, a second gear secured to the supporting member and a transmitting gear rotatably supported to the link member. The transmitting gear includes a first partial gear meshing with the first gear and a second partial gear meshing with the second gear. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying drawings, wherein: 
       FIG. 1  illustrates a perspective view of a seat apparatus according to the first embodiment of the present invention; 
       FIG. 2  illustrates a partial side view of the seat apparatus being folded state according to the first embodiment of the present invention; 
       FIG. 3  illustrates a partial side view of the seat apparatus being unfolded state according to the first embodiment of the present invention; 
       FIG. 4  illustrates a side view of the seat apparatus according to the first embodiment of the present invention; 
       FIG. 5  illustrates a side view of the seat apparatus according to the second embodiment of the present invention; 
       FIG. 6  illustrates a perspective view of a gear and link mechanism applied to the seat apparatus according to the second embodiment of the present invention; 
       FIG. 7  illustrates a side view of the seat apparatus according to the third embodiment of the present invention; and 
       FIG. 8  illustrates a side view of the seat apparatus according to the third embodiment of the present invention after the position of the seat apparatus is adjusted. 
   

   DETAILED DESCRIPTION 
   Embodiments of the present invention are explained referring to attached drawings  FIG. 1  through  FIG. 7 . A first embodiment of the present invention shown in  FIG. 4  relates to the seat apparatus  1  including a collapsible footrest  4 . The seat apparatus  1  also includes a seat back  2  and a seat cushion  3 . 
   As shown in  FIG. 1 , the seat cushion  3  includes a cushion frame  31  as a structural member for enhancing the strength of the seat cushion  3 . Further, a pair of brackets  78  is provided at an under surface of the front end of the cushion frame  31 . The brackets  78  are spaced in a seat width direction. 
   The footrest  4  including a link mechanism  7  as a main subject of the present invention is supported to the bracket  78 . The footrest  4  also includes a pair of arms  44  spaced in the seat width direction, and a U-shaped supporting member  41  extending in the seat width direction. The each end of the supporting member  41  is supported to the each arm  44 . In such configuration, the footrest  4  is freely folded or unfolded relative to the seat cushion  3  by the link mechanism  7 . 
   One end of a link member  45  being long shaped is connected to each arm  44  with a supporting shaft  76  which is secured to each arm  44 . The other end of the link member  45  is connected to each bracket  78  with a rotation shaft  75  which is rotatably supported on each bracket  78 . A transmitting gear  72  is rotatably attached to the link member  45  with a rotation shaft  75 . The transmitting gear  72  is shaped in a link shape. The transmitting gear  72  includes a first partial gear  72   a  and a second partial gear  72   b  facing each other relative to the rotation shaft  77 . 
   The transmitting gear  72  includes the first partial gear  72   a  and the second partial gear  72   b  at both ends thereof. Ranges of the teeth of respective first partial gear  72   a  and the second partial gear  72   b  correspond to a rotation angle of the transmitting gear  72 . The transmitting gear  72  is a long and narrow width shape so that the link mechanism  7  can be provided within a narrow space. Further, the characteristic of the actuation of the link mechanism  7  can be changed by changing a pitch circle diameter and the number of teeth of each first partial gear  72   a  and second partial gear  72   b  so as to be easily adapted to many applications. 
   As shown in  FIGS. 1 through 3 , a first gear  73  being meshing with the first partial gear  72   a  is fixed to the arm  44 , wherein the center of the point of the first gear  73  corresponds to the center point of the rotation shaft  76 , and a second gear  74  being meshing with the second partial gear  72   b  is fixed to the lower end of the bracket  78 , wherein the center point of the second gear  74  corresponds to the center point of the rotation shaft  75 . 
   One link member  45  is connected to the other link member  45  at the position where the rotation shafts  75  is provided with a rod  42  extending in the seat width direction so that both link members  45  can be integrally rotated. In  FIG. 1 , a lower end of a connecting arm  43  is connected to the center portion of the rod  42 . Further, a top end of the connecting arm  43 , extending upward, is connected to a driving rod  53  of a driving device  5  with a rotation pin  46 . 
   The driving device  5  is rotatably supported at the bracket  32 , fixed to the under surface of the cushion frame  31 , with a pin  33  through a supporting bracket  54 . The driving device  5  includes an electric motor  51  supported by the supporting bracket  54 , a decelerating mechanism portion  52 , a driving nut (not shown) housed in the decelerating mechanism portion  52  and rotated by an actuation from the electric motor  51 , a screw  53   a  engaging with the driving nut and a driving rod  53  being moved in longitudinal direction of the seat by the rotation of the driving nut actuated by the electric motor  51 . 
   An actuation of the seat apparatus  1  including the collapsible footrest  4  having the aforementioned configuration will be explained as follows. 
     FIG. 2  illustrates a condition of the link mechanism  7  when the footrest  4  shown in a solid line in  FIG. 4  is folded.  FIG. 3  illustrates a condition of the link mechanism  7  when the footrest  4  shown in a chain double-dashed line in  FIG. 4  is unfolded. 
   When the footrest  4  shown in  FIG. 2  is folded, the driving rod  53  becomes fully retracted state toward the rear direction of the seat as shown in  FIG. 2 . At this point, the link member  45  is fully rotated in clockwise direction relative to the rotation shaft  75 . The footrest  4  being folded condition is unfolded as shown in  FIG. 3  by energizing the electric motor  51  of the driving device  5  (shown in  FIG. 1 ) so as to push the driving rod  53  out in front direction of the seat. According to the rotation of the link member  45 , the second partial gear  72   b  of the transmitting gear  72  rotatably supported by the link member  45  meshes with the second gear  74  fixed to the bracket  78  so as to rotate in anticlockwise direction relative to the link member  45 . The first partial gear  72   a  of the transmitting gear  72  rotatably supported by the link member  45  meshes with the first gear  73  fixed to the arm  44  so as to rotate in clockwise direction relative to the link member  45 . Thus, the footrest  4  is unfolded as shown in the chain double-dashed line in  FIG. 4 . The unfolded footrest  4  is actuated to be folded again by reversing the rotation of the motor  51 . 
   Another example of the seat apparatus  10  being retractable as shown in  FIG. 5  will be explained as a second embodiment of the present invention. 
   In the second embodiment, the state of the seat apparatus  10  can be changed from the seating state to the retractable folded state. The seat apparatus  10  is supported by a front leg portion and a rear leg portion  170  to be stand on a vehicle floor in the seating state, and the seat apparatus  10  is housed in a concave portion  12  provided under the floor  12  in the retractable folded state. Such seat apparatus  10  includes the gear and link mechanism described in the first embodiment, which is applied to the rear leg portion  170 . Thus, the seat apparatus  10  becomes retractable. 
     FIG. 6  indicates the rear leg portion  170  including the gear and link mechanism. As shown in  FIGS. 5 and 6 , a second gear  174   a  is provided at a supporting bracket  174  of the rear leg portion  170  installed on the floor  12 . A transmitting gear  172  is rotatably supported by a supporting post  145  of the rear leg portion  170  by a rotation shaft  177 . The supporting post  145  is provided as a link member of the gear link mechanism. On the other hand, a first gear  173   a  is formed at the rear end portion of a frame  173  double as the cushion frame. The transmitting gear  172  includes a first partial gear  172   a  meshing with the first gear  173   a  and a second partial gear  172   b  meshing with the second gear  174   a.    
   Further, the supporting post  145  is connected to the front leg portion  81  with a connecting rod  85 . The front leg portion  81  hinge connected to the front end of the frame  173  is folded by the connecting rod  85  in conjunction with the retracting actuation of the seat apparatus  10 . The front leg portion  81  includes a lock mechanism  8  at the lower end portion of the front leg portion  81  for securing the position of the seat apparatus  10  at the seating position. The lock mechanism  8  includes a striker  82  fixed on the floor  12  and a hook  83  rotatably supported at the front leg potion  81  by a shaft  83   a  so as to lock the seat apparatus  10  to the floor  12 . 
   The seat apparatus  10  having the aforementioned configuration is housed in the concave portion as follows. First, the seat back  2  of the seat apparatus  1  is folded on the seat cushion  3  by operating an angle adjusting mechanism (not shown), then the lock mechanism  8  is unlocked by rotating the hook  83 , finally the seat apparatus  10  is pushed backward and housed in the concave portion  12   a . The position of the seat apparatus  10  is maintained at a predetermined position by the actuation of the gear and link mechanism of the rear leg portion  170 , so that the retracting operation becomes very simple. 
   Another configuration of the seat apparatus  10  according to the present invention will be explained as a third embodiment. In the third embodiment, the angle of the seat back  2  can be adjusted as shown in  FIGS. 7 and 8 . 
   Such seat apparatus  10  used as a rear seat of the vehicle includes the seat cushion  3  installed on a flat portion  12   a  of the vehicle floor  12 , and the seat back  2  standing along a rear end surface  12   b  of the compartment and being rotatable about the supporting shaft  276  relative to the seat cushion  3  so as to adjust the angle of the seat back  2 . The gear and link mechanism as explained in  FIGS. 1 and 2  is applied to the angle adjusting mechanism  270  of the seat back  2 . 
   The seat back  2  includes a frame  245  for securing the strength thereof. On the other band, the seat cushion  3  is supported to the floor  12  through a seat slide apparatus  9  attached on the flat portion  12   a  of the floor  12 . The seat slide apparatus  9  is driven by a known driving apparatus (not shown) including an electric motor. The seat slide apparatus  9  includes an upper rail  91  and a lower rail  92 , which are slidably engaging each other in longitudinal direction of the seat (in approximately horizontal direction in  FIG. 7 ). Further, the upper rail  91  is fixed to the seat cushion  3 , and the lower rail  9  is fixed to the flat portion  12   a  of the floor  12 . A bracket  273  extending upward is fixed to the rear end portion of the upper rail  91 , and the frame  245  as a link member of the gear and link mechanism is rotatably supported at the bracket  273  by the supporting shaft  276 . The bracket  273  includes a first gear  273   a  at a rear end portion thereof. A transmitting gear  272  including a first partial gear  272   a  which is meshing with the first gear  273   a  is rotatably supported to the frame  245  by a rotation shaft  277 . Further, a supporting member  274  is rotatably attached to the frame  245  by the rotation shaft  275 . The supporting member  274  includes a second gear  274   a  meshing with a second partial gear  272   b  of the transmitting gear  272 . On the other hand, the driving device  5  for rotating the supporting member  274  relative to the rotation shaft thereof is provided between the supporting member  274  and the rear end surface  12   b  of the compartment. As explained above, the driving device  5  includes the motor  51  and the driving rod  53 , and once the motor  51  is energized, the driving rod  53  is reciprocated to rotate the second gear  274   a.    
   The seat apparatus  10  including the angle adjusting mechanism  270  having the aforementioned configuration is actuated by a controlling device (not shown) in which the driving device  5  and a driving device (not shown) of the seat slide apparatus  9  are actuated by the instruction of the operator. Then the position of the seat apparatus  10  is changed from one position shown in a chain double-dashed line to the other position shown in another chain double dashed line shown in  FIG. 8 . At this point, the second gear  274   a  is rotated by the driving device  5  relative to the frame  245 , the transmitting gear  272  is rotated, finally the frame  245  is rotated relative to the bracket  273  due to the meshing actuation between the first partial gear  272   a  and the first gear  273   a . As a result, the position of the seat cushion can be adjusted by the seat slide apparatus  9 , at the same time, the angle of the seat back  2  relative to the seat back  2  is determined based on the positions and the postures of the frame  245  and the upper rail  91 .