Abstract:
A vehicle seat sliding device includes: a first rail adapted to be fixed to one of a vehicle floor and a seat; a second rail adapted to be fixed to the other one of the vehicle floor and the seat, and coupled to the first rail in a relatively movable manner; an engagement member, which selectively limits and permits the relative movement of the first and the second rails; an operation member configured such that operating force to cancel the restriction of the relative movement in the second rail is transmitted to the engagement member; and a cover mounted on the first end of the second rail to close the first end. The cover has an engagement piece, which engages with a support wall provided in the second rail and restricts the pivoting of the cover when pressed against the operation member.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a vehicle seat sliding device. 
     BACKGROUND OF THE INVENTION 
     Patent Document 1 describes an example of a known vehicle seat sliding device. Such a vehicle seat sliding device includes lower rails and upper rails, and the upper rails are coupled with the lower rails in a movable manner. A plastic cover is mounted on the upper rail, which is formed by a plate, such that the cover closes a first end located at one end of the upper rail. Direct interference between the first end and surrounding parts may be avoided by reducing exposure of the first end of the upper rail in this manner. 
     PATENT DOCUMENT 
     Patent Document 1 
     
         
         Japanese Laid-Open Patent Publication No. 2010-95096 
       
    
     SUMMARY OF THE INVENTION 
     In the seat sliding device of Patent Document 1, the cover is mounted as an exclusive part functioning and shaped to avoid interference between the first end of the upper rail and the surrounding parts. Therefore, although it is presently desirable that various parts be provided with multiple functions to reduce the number and weight of components, the cover is an inefficient part having only a single function. 
     It is an object of the present invention to provide a vehicle seat sliding device that realizes multiple functions for a cover that closes an end of a rail. 
     In order to achieve the above described objective, a vehicle seat sliding device including a first rail, a second rail, an engagement member, an operation member and a cover is provided. The first rail is adapted to be fixed to one of a vehicle floor and a seat. The second rail is adapted to be fixed to the other one of the vehicle floor and the seat. The second rail is coupled to be movable relative to the first rail, and the second rail includes two side walls arranged in a lateral direction that is perpendicular to a longitudinal direction of the second rail, a coupling wall, which is arranged to face the first rail in a vehicle height direction and which couples basal ends of the side walls that are separated from the first rail, and a first end located at one end in the longitudinal direction. The engagement member selectively restricts and permits relative movement of the first rail and the second rail. The operation member is inserted into the second rail in the longitudinal direction, linked to the engagement member, and elastically held by a biasing member to come into contact with a support wall arranged in the second rail. The operation member is configured to pivot about a location contacting the support wall against biasing force of the biasing member to approach a portion of the coupling wall at the first end of the second rail so that operation force for disengaging the relative movement is transmitted to the engagement member. The cover is mounted on the first end of the second rail to close the first end. The cover includes an engagement piece, which restricts pivoting of the cover when the cover is engaged with the support wall and is pressed against the operation member. 
     According to the above configuration, the cover, which closes the first end, is mounted on the first end of the second rail. This limits exposure of the first end so that the direct contact of the first end with surrounding parts is avoided. When the vehicle vibrates and swings the operation member about the portion contacting the support wall, for example, the operation member is brought into contact with the cover when the operation member approaches the coupling wall at the first end. Accordingly, the operation member may limit the generation of the noise as compared to when the operation member directly contacts, for example, the first end. Further, when the operation member is pivoted against the biasing force of the biasing member to transmit the operation force that cancels the restriction of the relative movement of the first rail and the second rail to the engagement member, even if the cover is pressed by the operation member, the pivoting of the cover resulting from the pressing is limited by the engagement piece. Accordingly, the separation of the cover from the first end is limited when the cover is pivoted. That is, the cover functions to limit the noise by contacting the operation member, while functioning to prevent removal of the cover from the first end with the engagement piece when the cover is pressed by the operation member. 
     According to the second embodiment of the present invention, a vehicle seat sliding device including a first rail, a second rail, an engagement member, an operation member and a cover is provided. The first rail is adapted to be fixed to one of a vehicle floor and a seat. The second rail is adapted to be fixed to the other one of the vehicle floor and the seat. The second rail is coupled to be movable relative to the first rail. The second rail includes two side walls arranged in a lateral direction perpendicular to a longitudinal direction of the second rail, a coupling wall, which is arranged to face the first rail in a vehicle height direction and which couples basal ends of the two side walls that are separated from the first rail, and a first end located at one end in the longitudinal direction. The engagement member selectively restricts and permits relative movement of the first rail and the second rail. The operation member is inserted into the second rail in the longitudinal direction, linked to the engagement member, and elastically held by a biasing member to come into contact with a support wall arranged in the second rail at a location contacting the support wall. The operation member is configured to pivot about the location contacting the support wall against biasing force of the biasing member to approach the coupling wall at the first end of the second rail so that operation force for canceling the restriction of the relative movement is transmitted to the engagement member. The cover is mounted on the first end to close the first end. The cover includes an opposing surface, which opposes the operation member at a portion corresponding to the two side walls, and a sliding bead, which protrudes from the opposing surface and extends in a direction transverse to a path along which the operation member is inserted into the second rail to press the operation member. 
     According to the above configuration, the operation member inserted into the second rail on which the cover is mounted is positioned in the lateral direction when pressed against the sliding bead. The sliding bead limits the backlash of the operation member in the lateral direction. Accordingly, while positioning the operation member in the lateral direction in a more stable state with the sliding bead that contact the operation member in a concentrated manner, an increase in the sliding resistance during the release operation, that is, a decrease in the operability of the operation member may be limited. Further, the backlash in the lateral direction and the pivot direction during the release operation of the operation member, and the generation of noise caused by the backlash are limited. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view illustrating a seat sliding device and a vehicle seat according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view illustrating the seat sliding device shown in  FIG. 1  taken along line  2 - 2  in  FIG. 3(   a ); 
         FIG. 3(   a ) is a plan view illustrating the seat sliding device; 
         FIG. 3(   b ) is a side view illustrating the seat sliding device; 
         FIG. 4(   a ) is a cross-sectional view taken along line  4 A- 4 A in  FIG. 3(   a ); 
         FIG. 4(   b ) is a cross-sectional view taken along line  4 B- 4 B in  FIG. 3(   b ); 
         FIG. 5  is a perspective view illustrating a portion of the seat sliding device; 
         FIG. 6(   a ) is a cross-sectional view illustrating the movement of the seat sliding device; 
         FIG. 6(   b ) is a cross-sectional view illustrating the movement of the seat sliding device; 
         FIG. 7(   a ) is a front view illustrating a cover; 
         FIG. 7(   b ) is a side view illustrating the cover; and 
         FIG. 7(   c ) is a cross-sectional view taken along line  7 C- 7 C in  FIG. 7(   a ). 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present invention will now be described with reference to  FIGS. 1 to 7 . As shown in  FIG. 1 , lower rails  3 , which serve as first rails, are fixed to a vehicle floor  2  such that each lower rail  3  extends in the front-back direction of a vehicle. Upper rails  4 , which serve as second rails, are mounted on the corresponding lower rails  3  and movable manner relative to the corresponding lower rails  3  in the front-back direction. 
       FIG. 1  shows one of two paired sets of the lower rail  3  and the upper rail  4 . The two paired sets are spaced apart from each other in the lateral direction of the vehicle (the direction perpendicular to the plane of  FIG. 1 ). The left one of the paired sets facing toward the front is shown in  FIG. 1 . A seat  5  for seating a passenger is fixed to and supported by the upper rails  4 . The movement of the upper rails  4  relative to the lower rails  3  is basically restricted. A release handle  6 , which serves as an operation member, is provided to cancel the restriction. 
     As shown in  FIG. 2 , the lower rail  3  is formed by a plate and includes two first side walls  11 , which project from the two lateral sides, and a first coupling wall  12 , which couples basal ends, that is, lower ends of the first side walls  11 . A first folded wall  13  extends inward in the lateral direction from a distal end, or upper end, of each first side wall  11  and is further folded back toward the coupling wall  12  such that the first folded wall  13  is formed continuously with the first side wall  11 . 
     The upper rail  4  is formed by joining an upper end of substantially stair-shaped plate P 1  and an upper end of a substantially flat plate P 2 . The upper rail  4  includes two second side walls  14 , which serve as side walls and extend in the vertical direction between the first folded walls  13  of the lower rail  3 , and a second coupling wall  15 , which serves as a coupling wall and couples basal ends, or upper ends, of the second side walls  14  that are separated from the lower rail  3 . The upper rail  4  includes a vertical wall  17  formed by the joined portions of the plate P 1  and the plate P 2  and extending upward along one side (right side as viewed in the drawing) of the second side wall  14 . A second folded wall  16 , which extends outward in the lateral direction from a distal end, or lower end, of each second side wall  14  is folded to be surrounded by the corresponding first side wall  11  and the corresponding first folded wall  13  such that the second folded wall  16  is continuous with the second side wall  14 . 
     In this manner, the lower rail  3  and the upper rail  4  each have a substantially U-shaped cross-section and are engaged with each other such that their openings face each other. The engagement of the first folded wall  13  and the second folded wall  16  mainly restricts separation of the lower rail  3  and the upper rail  4  in the vertical direction. The lower rail  3  and the upper rail  4  form a rail cross-section that is substantially tetragonal and box-shaped. The lower rail  3  and the upper rail  4  cooperate to configure an inner space S. 
     As shown in  FIGS. 3(   a ) and  3 ( b ), two rollers  20 , a front one and a rear one, are arranged between each second folded wall  16  and the opposing first side wall  11 . The upper rail  4  is supported to be slidable relative to the corresponding lower rail  3  in the longitudinal direction (front-back direction) by allowing the rollers  20  to roll between the upper rail  4  and the lower rail  3 . 
     A plurality of tetragonal lock holes  13   a  are formed in predetermined intervals in the longitudinal direction of each lower rail  3  in the basal ends, or upper ends, of the two first folded walls  13  of each lower rail  3 . The lock holes  13   a  are open upward. 
     A plurality of (three) bores  14   a ,  14   b , and  14   c  are formed in the predetermined intervals in the longitudinal direction of each upper rail  4  in intermediate portions of the two second side walls  14  of the upper rail  4  in the longitudinal direction. The bores  14   a  to  14   c  are open in the lateral direction and arranged at positions that may be aligned with a plurality (three) of the lock holes  13   a  that are arranged next to one another in the longitudinal direction of the lower rail  3 . 
     A plurality of (three) fitting grooves  16   a  are formed in the predetermined intervals in the longitudinal direction in the distal ends, or upper ends, of the two second folded walls  16  of the upper rail  4 . The fitting grooves  16   a  are open upward and respectively arranged facing the bores  14   a  to  14   c  in the lateral direction. The fitting grooves  16   a  are arranged at positions that may be aligned with a plurality of (three) the lock holes  13   a  that are arranged next to one another in the longitudinal direction of the lower rail  3 . 
     Two circular bearing holes  21  are arranged to face each other in the lateral direction frontward from the bores  14   a  to  14   c  in the two second side walls  14  of the upper rail  4 . The axes of the bearing holes  21  extend in the lateral direction. A substantially tetragonal frame-shaped support wall  22  is formed by cutting out and bending a front end portion of the second side wall  14  of the plate P 2  in one side of the upper rails  4 , that is, the lower side of the upper rails  4  in  FIG. 3(   a ), in the lateral direction of the second side wall  14  toward the space S. That is, as shown in  FIGS. 4(   a ) and  4 ( b ), the support wall  22  has an upper rim  22   a  and a lower rim  22   b , which are arranged in the height direction and extend in the lateral direction, and a pair of side rims  22   c  and  22   d , which are arranged in the lateral direction and connect free ends and fixed ends of the upper rim  22   a  and the lower rim  22   b  in the height direction. A support hole  22   e , which is open in the front-back direction, is formed in the support wall  22 . 
     As shown in  FIG. 4(   a ), a hook-shaped stopper  23  is formed by cutting out and bending the second coupling wall  15  of each upper rail  4  downward into the space S rearward from the support wall  22 . Two substantially tetragonal support holes  24 , which are arranged in the front-back direction, are formed in the second coupling wall  15  of the upper rail  4  frontward from the bearing holes  21  and rearward from the stopper  23 . 
     As shown in  FIG. 5 , a plastic cover  50  is mounted on a front end, or first end, of the upper rail  4  to cover the first end. The cover  50  has two lateral wall cover portions  51  mounted on the first end of the upper rail  4 , that is, the front ends of the two second side walls  14 , and a coupling wall cover portion  52 , which connects upper ends of the lateral wall cover portions  51  and is also mounted on the second coupling wall  15  at the first end. The cover  50  is substantially U-shaped in conformance with a projected plane of the upper rail  4  as viewed in the longitudinal direction. As shown in  FIGS. 4(   a ) and  4 ( b ), a fitting groove  55  having a substantially L-shaped cross-section is formed by cutting out the cover  50  in conformance with a corner of the upper rail  4  located at the first end and facing the space S. 
     As shown in  FIG. 5 , the cover  50  has folded wall cover portions  53 , which extend outward in the lateral direction from lower ends of the two lateral wall cover portions  51  and which are mounted on the second folded walls  16  of the first end of the upper rail  4 , and a vertical wall cover portion  54 , which extends upward from the coupling wall cover portion  52  and also mounted on a basal end of the first vertical wall  17 . 
     As shown in  FIG. 6(   a ), a lower surface of the coupling wall cover portion  52  defines a slanted surface  52   a  having a slanting angle set to rise toward the front with a cross-section reduced forward to form a slanted angle. As shown in  FIG. 6(   b ), a flange-shaped engagement piece  56  is integrally formed with each lateral wall cover portion  51 . The engagement piece  56  extends rearward along an inner wall surface of the lateral wall cover portion  51 . The engagement piece  56  is inserted into the support hole  22   e  of the support wall  22  when the cover  50  is engaged with the first end of the upper rail  4 . The engagement piece  56  has an engagement projection  56   a , which is curved and protruded downward. The engagement piece  56  is set such that the engagement projection  56   a  presses and contacts the lower rim  22   b  of the support wall  22 . As shown in  FIGS. 7(   a ) to  7 ( c ), a hook-shaped engagement hook  56   b , which protrudes outward in the lateral direction, is formed on a distal end of each engagement piece  56 , which extends through the support hole  22   e . Each engagement hook  56   b  engages the corresponding one of the side rims  22   c  and  22   d  of the support wall  22 . A strip-shaped sliding bead  57  is formed on each lateral wall cover portion  51 . The sliding bead  57  extends such that it protrudes from an inner wall surface of the lateral wall cover portion  51  inward in the lateral direction. The sliding bead  57  extends in the height direction. 
     As shown in  FIGS. 3(   a ) and  3 ( b ), an engagement member  30 , which is formed by a plate, is arranged in the space S defined between the lower rail  3  and the upper rail  4  such that the engagement member  30  extends in the front-back direction. The engagement member  30  has two vertical walls  31  extending upward from two edges, in the lateral direction, of a longitudinally intermediate portion of the engagement member  30 . The distance between the vertical walls  31  in the lateral direction is set to be smaller than the distance between the two second side walls  14  of the upper rail  4  in the lateral direction. Two shafts  32 , which are supported by the bearing holes  21 , protrude outward in the lateral direction from rear ends of the vertical walls  31 . Each shaft  32  has a substantially cylindrical shape and includes a closed end. The shafts  32  are fitted into and are supported by the bearing holes  21  so that the engagement member  30  is coupled with the upper rail  4  in a pivotal manner about an axis that extends in the lateral direction. 
     An input unit  33 , which extends forward and has a smaller width than the distance between the two vertical walls  31  in the lateral direction, is formed frontward from the vertical walls  31  of the engagement member  30 . As shown in  FIG. 4(   a ), a front end of the input unit  33  forms a contact portion  33   a  having the shape of a substantially arcuate wall that bulges upward. A flat engagement unit  34 , which extends rearward, is formed rearward from the two vertical walls  31  of the engagement member  30 . As shown in  FIG. 3  ( a ), the engagement unit  34  includes a substantially tetragonal main body  34   a , which has a smaller width than the distance between the two second side walls  14  of the upper rail  4  in the lateral direction, and a plurality of (three on each side, six in total) engagement hooks  34   b ,  34   c , and  34   d , which protrude outward from a rear end of the main body  34   a  in the lateral direction. The engagement hooks  34   b  to  34   d  on each side are arranged in the longitudinal direction (front-back direction) of the engagement member  30  in the predetermined intervals. The engagement member  30 , which is coupled to the upper rail  4 , is permitted to pivot about the shafts  32  under a situation in which the main body  34   a  is arranged between the two second side walls  14  and the engagement hooks  34   b  to  34   d  are all inserted into the corresponding bores  14   a  to  14   c  from the inner side and provided with play. 
     As shown by the solid lines in  FIG. 2 , when the engagement member  30  pivots about the shafts  32  such that the engagement unit  34  is lowered, each of the engagement hooks  34   b  to  34   d  can be fitted into the corresponding one of the lock holes  13   a  and the corresponding one of the fitting grooves  16   a . When each of the engagement hooks  34   b  to  34   d  is fitted into the corresponding one of the lock holes  13   a  and the corresponding one of the fitting grooves  16   a , each of the engagement hooks  34   b  to  34   d  fits into the corresponding one of the lock holes  13   a  between the bores  14   a  to  14   c  and the fitting grooves  16   a , into which the engagement hooks  34   b  to  34   d  are inserted. This restricts relative movement of the lower rail  3  and the upper rail  4  in an appropriate manner. 
     In contrast, as shown by the double-dashed lines in  FIG. 2 , when the engagement member  30  pivots about the shafts  32  such that the engagement unit  34  is raised, each of the engagement hooks  34   b  to  34   d  is set to be removed from the corresponding one of the lock holes  13   a . This cancels the restriction of the relative movement of the lower rail  3  and the upper rail  4 . 
     As shown in  FIGS. 3(   a ) and  3 ( b ), a torsion spring  41 , which serves as a biasing member and is made of a wire material, is arranged in the space S defined between the lower rail  3  and the upper rail  4 . The torsion spring  41  is substantially C-shaped and open rearward as viewed from above. The torsion spring  41  has two bilaterally symmetric extended portions  41   a , which extend in the front-back direction, and a connecting portion  41   b , which connects front ends of the two extended portions  41   a  in the lateral direction. The torsion spring  41  is positioned in the space S and fastened to the second coupling wall  15  to partially protrude from the two support holes  24 . Further, rear ends of the extended portions  41   a  elastically contact an upper surface of the engagement unit  34  at a location rearward from the bearing holes  21  (shafts  32 ). Accordingly, the engagement unit  34  of the engagement member  30  is biased by the torsion spring  41  in the direction in which the engagement unit  34  is lowered, that is, in the direction in which each of the engagement hooks  34   b  to  34   d  is fitted into the corresponding one of the lock holes  13   a  and the corresponding one of the fitting grooves  16   a . The connecting portion  41   b  of the torsion spring  41  is arranged between the support wall  22  and the stopper  23  in the front-back direction. 
     The release handle  6  is formed by bending a tubular material. The release handle  6  is formed such that it bridges the two upper rails  4  in the lateral direction at the front ends of the two upper rails  4 . As shown in  FIGS. 4(   a ) and  4 ( b ), a distal portion  61 , which extends rearward of the release handle  6 , has the shape of a substantially tetragonal tube with a smaller size than the opening width of the support wall  22  (support hole  22   e ). A bottom wall of the release handle  6  includes a slit-shaped support groove  62 . A pressing portion  63  is formed by pressing a rear end of the distal portion  61  in the vertical direction into a flat shape. 
     When each distal portion  61  is inserted into the corresponding support wall  22  from the front, the connecting portion  41   b  of the torsion spring  41  is fitted into the support groove  62 . This locks and restricts separation of the release handle  6 . At this time, each distal portion  61  is biased by the torsion spring  41  in the support groove  62  and raised. This holds the distal portion  61  such that the upper surface of the distal portion  61  contacts the opposing inner wall surface of the support wall  22 . At this time, as shown in  FIG. 4(   a ), the pressing portion  63  is arranged at the upper side of the input unit  33  of the engagement member  30  with a gap provided in between. That is, the torsion spring  41  further functions to elastically hold the release handle  6  at a predetermined initial position such that the release handle  6  maintains a predetermined linked state with the engagement member  30 . 
     When the release handle  6  (distal portion  61 ) is held above the upper portion of the upper rail  4 , the cover  50  is pressed against the distal portion  61  at the two sliding beads  57 . This is to position the distal portion  61  of the release handle  6  in the lateral direction in a further stable state with the two sliding beads  57 , which linearly contact the distal portion  61 . 
     When the distal portion  61  of the release handle  6  pivots in the clockwise direction as shown in  FIG. 4(   a ) about a contact point (hereinafter, referred to as “support point O 1 ”) between the distal portion  61  and the support wall  22 , the input unit  33  of the engagement member  30  is lowered so that the engagement member  30 , which is pressed by the pressing portion  63 , pivots in the counterclockwise direction as shown in  FIG. 4(   a ). This moves the engagement unit  34  of the engagement member  30  in the direction in which the engagement unit  34  is raised against the biasing force of the torsion spring  41 , that is, each of the engagement hooks  34   b  to  34   d  is removed from the corresponding one of the lock holes  13   a . The support point for the pivoting of the distal portion  61  (release handle  6 ) is set using the support wall  22  to balance the operation force and the operation amount of the release handle  6  necessary to release the engagement member  30  based on the principle of leverage. The pivot direction of the engagement member  30  is opposite to the pivot direction of the release handle  6 . 
     When the distal portion  61  contacts the coupling wall cover portion  52  of the cover  50  as the distal portion  61  of the release handle  6  pivots, the distal portion  61  comes into planar contact with the slanted surface  52   a . That is, the slanted angle of the slanted surface  52   a  is set at an angle that is the same as the slanted angle of the distal portion  61  when the distal portion  61  presses the coupling wall cover portion  52 . This is to disperse loads on the contact surface when the distal portion  61  contacts and presses the coupling wall cover portion  52  through the planar contact with the slanted surface  52   a . At this time, the cover  50  is pressed by the distal portion  61  so as to pivot about the coupling wall cover portion  52 . However, the pivoting of the cover  50  is limited by the engagement pieces  56 , which are engaged with the support wall  22 . This suppresses removal of the cover  50  from the first end of the upper rail  4 , which is caused by the pivoting of the cover  50 . 
     When the release handle  6  (distal portion  61 ) is held above the upper portion of the upper rail  4 , the stopper  23  is arranged to block the rearward movement track of the pressing portion  63 . When inserting each distal portion  61  into the support wall  22  during a coupling process of the release handle  6 , the engagement of the stopper  23  obviates excessive insertion of the distal portion  61 . 
     Next, the operation of the present embodiment will be described. 
     First, it is assumed that the operation force of the release handle  6  is released. At this time, each distal portion  61 , which is biased and held by the torsion spring  41  in the support groove  62 , is positioned such that the upper surface of the distal portion  61  contacts the opposing surface of the support wall  22  (upper rim  22   a ). The pressing portion  63  is arranged above the input unit  33  of the engagement member  30  with a gap provided in between. Accordingly, the engagement member  30  released from the distal portion  61  (release handle  6 ) is biased by the torsion spring  41  in the direction in which the engagement unit  34  is lowered, that is, in a direction in which each of the engagement hooks  34   b  to  34   d  is fitted into the corresponding one of the lock holes  13   a  and the corresponding one of the fitting grooves  16   a . This fits each of the engagement hooks  34   b  to  34   d  into the corresponding one of the lock holes  13   a  and the corresponding one of the fitting grooves  16   a  thus restricting relative movement of the lower rail  3  and the upper rail  4  in an appropriately manner. Further, the position of the seat  5  supported by the upper rails  4  in the front-back direction is maintained. 
     Here, it is assumed that the release handle  6  is operated to raise its front end. At this time, the distal portion  61  pivots about the support point O 1  in the direction in which the pressing portion  63  is lowered. Thus, the pressing portion  63  presses the input unit  33  of the engagement member  30 . Accordingly, the engagement member  30  pivots in the direction in which the engagement unit  34  is raised about the shafts  32  against the biasing force of the torsion spring  41 , that is, in the direction in which each of the engagement hooks  34   b  to  34   d  is removed from the corresponding one of the lock holes  13   a . Therefore, each of the engagement hooks  34   b  to  34   d  is removed from the corresponding one of the lock holes  13   a  to cancel the restriction of the relative movement of the lower rail  3  and the upper rail  4 . This allows for position adjustment of the seat  5 , which is supported by the upper rails  4 , in the front-back direction. 
     As described in details above, the present embodiment has the following advantages. 
     (1) The cover  50 , which closes the first end, or the front end of the upper rail  4 , is mounted on the first end. Thus, exposure of the first end is limited, and direct interference of the first end with the surrounding parts is avoided. Further, for example, when the vehicle vibrates and swings the release handle  6  about the portion contacting the support wall  22  (support point O 1 ), the release handle  6  is brought into contact with the cover  50  (coupling wall cover portion  52 ) when the release handle  6  approaches the second coupling wall  15  of the first end of the upper rail  4 . Accordingly, the release handle  6  may limit the generation of noise as compared to when the release handle  6  directly contacts, for example, the first end (e.g., metal contact). That is, the coupling wall cover portion  52  functions as a simple stopper in the input direction during a release operation of the release handle  6  so that pivoting (backlash) in the input direction and the generation of the noise caused by the pivoting are suppressed. Further, when the release handle  6  is pivoted against the biasing force of the torsion spring  41  to transmit operation force that cancels the restriction of the relative movement of the lower rail  3  and the upper rail  4  to the engagement member  30 , even if the cover  50  is pressed by the release handle  6 , pivoting of the cover  50  resulting from the pressing is restricted by the engagement pieces  56 . That is, the two engagement pieces  56  function as stoppers for the cover  50  in the input direction during a release operation of the release handle  6  to limit pivoting (backlash) in the input direction. Accordingly, separation of the cover  50  from the first end is limited when the cover  50  is pivoted. That is, the cover  50  functions to limit noise by contacting the release handle  6 , while functioning to prevent removal of the cover  50  from the first end with the engagement pieces  56  when the cover  50  is pressed by the release handle  6 . 
     (2) The release handle  6  inserted into the upper rail  4  on which the cover  50  is mounted is positioned in the lateral direction when pressed against the two sliding beads  57 . The two sliding beads  57  limit the backlash of the release handle  6  in the lateral direction. Accordingly, while positioning the release handle  6  in the lateral direction in a more stable state with the two sliding beads  57  that contact the release handle  6  in a concentrated manner, that is, linearly contacts the release handle  6 , an increase in the sliding resistance during the release operation, that is, a decrease in the operability of the release handle  6  may be limited. Further, the backlash in the lateral direction and the pivot direction during the release operation of the release handle  6 , and the generation of noise caused by the backlash are limited. 
     (3) When the release handle  6  pivots and thereby presses the cover  50 , the release handle  6  presses, in planar contact, the slanted surface  52   a  of the cover  50  (coupling wall cover portion  52 ), which has a slanted angle set for such a case. This disperses the load on the portion that contacts the cover  50 . Therefore, the case that the cover  50  is pressed by the centered loads from the release handle  6  is avoided so that the deformation of the cover  50  is limited. 
     (4) Since the engagement hooks  56   b  are engaged with the side rims  22   c  and  22   d  of the support wall  22 , separation of the cover  50  is restricted in the direction of the relative movement (front-back direction) of the lower rail  3  and the upper rail  4 . 
     (5) When the distal portion  61  of the release handle  6  is excessively inserted into the support wall  22  of the upper rail  4 , the rear end of the pressing portion  63  contacts and engages with the stopper  23 . This obviates such an excessive insertion of the distal portion  61  of the release handle  6 . Since the stopper  23  is formed through a simple process of just cutting out and bending the second coupling wall  15  of the upper rail  4 , the number of parts and the number of manufacturing steps may be reduced. 
     The above described embodiment may be modified as follows. 
     The distal portion ( 61 ) of the release handle  6  may be cylindrical. In this case, the distal portion of the release handle  6  comes into point contact with the sliding beads  57 . 
     The sliding beads  57  may extend in any direction as long as the direction is transverse to a path along which the release handle  6  is inserted. 
     The support wall  22  may be configured by only the upper rim  22   a  and the lower rim  22   b , and the side rims  22   c  and  22   d  may be omitted. That is, the support wall  22  need not be shaped like a tetragonal frame. 
     A biasing member configured by a plate spring may be adopted in place of the torsion spring  41 . 
     The biasing member, which biases the engagement member  30 , and a member, which holds the release handle  6  (distal portion  61 ), may be separately provided. 
     The fixing relationship (that is, vertical arrangement) of the lower rails  3  and the upper rails  4  to the vehicle floor  2  and the seat  5  may be inversed. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     S . . . Space,  2  . . . Vehicle Floor,  3  . . . Lower Rail (First Rail),  4  . . . Upper Rail (Second Rail),  5  . . . Seat,  6  . . . Release Handle (Operation Member),  11  . . . First Side wall,  12  . . . First Coupling wall,  13  . . . First Folded Wall,  13   a  . . . Lock Hole (Portion to be Locked),  14  . . . Second Side Wall (Side wall),  14   a  to  14   c  . . . Bores,  15  . . . Second Coupling Wall (Coupling Wall),  16  . . . Second Folded Wall (Folded Wall),  22  . . . Support Wall,  30  . . . Engagement Member,  41  . . . Torsion Spring (Biasing Member),  50  . . . Cover,  51  . . . Lateral Wall Cover Portion,  52  . . . Coupling Wall Cover Portion,  52   a  . . . Slanted Surface,  56  . . . Engagement piece,  56   a  . . . Engagement Projection,  56   b  . . . Engagement Hook, and  57  . . . Sliding Bead (Sliding Portion).