Abstract:
A seat sliding apparatus has left and right rail pairs each including an upper rail for supporting a seat and a lower rail for fixing to a vehicle body. In each of the left and right rail pairs, left and right resin sliders are attached to lateral edges of the upper or lower rails, to facilitate sliding motion of the upper rail along the lower rail. Each resin slider has a larger engaging portion and a smaller engaging portion. The left and right resin sliders are arranged in parallel to each other, but extended in opposite direction, so that the larger engaging portion is ahead of the smaller engaging portion in one of the left and right resin slider whereas, in the other resin slider, smaller engaging portion is ahead of the larger engaging portion.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a seat sliding apparatus for a vehicle, and more particularly to a resin slider interposed between an upper rail and a lower rail of a seat sliding apparatus, and an assembled structure of resin sliders and upper and lower rails.  
           [0002]    A seat sliding apparatus includes a pair of left and right lower rails secured to a vehicle body through supporting legs, a pair of left and right upper rails engaged with the left and right lower rails, respectively, in such a slidable manner that the upper rail can slide on the lower rail along the longitudinal direction on each of the left and right sides. A vehicle seat is fixedly mounted on the upper rails. A slide lock mechanism is arranged to allow the upper rails to slide along the lower rails to adjust the seat to a desired position, and to lock the upper rails to secure the seat at the desired position.  
           [0003]    There are various types of slide rail mechanisms having different cross sectional shapes and different rail engaging structures. FIGS. 7 and 8 show a widely used type of earlier technology. A lower rail  1  has a channel section, rollers  2  are disposed on the inner bottom of the lower rail  1 , and an upper rail  3  having a generally inverted-U section is placed on the rollers  2  in an inverted position.  
           [0004]    Left and right resin sliders  4  are interposed between the upper and lower rails, to eliminate or reduce vibrations due to looseness, and noise due to metal-to-metal contact during vehicle movement or seat sliding operation, and to reduce the friction for smooth sliding motion. The lower rail  1  has left and right inward flanges  1   a  each having a downwardly bent edge. The upper rail  3  is placed between the left and right inward flanges  1   a  of the lower rail  1 . The upper rail  3  has left and right outward flanges  3   a  each having an upwardly bent edge. The resin sliders  4  are interposed between the inward flanges  1   a  of the lower rail  1  and the outward flanges  3   a  of the upper rail  3 . Each resin slider  4  is attached, at each of front and rear end portions, to the left or right downward edge of the inward flange  1   a  by engagement between an engaging hole  5  formed in the inward flange  1   a  and an engaging portion  7  formed in the resin slider  4 . Each engaging portion  7  has a hook portion  6 .  
         SUMMARY OF THE INVENTION  
         [0005]    To meet the demand for size reduction of the seat sliding apparatus, some resin sliders are so shaped as to have an asymmetrical cross section having unequal left and right halves. When, for example, the distance between each upright wall of the upper rail  3  and the adjacent downward edge of the lower rail is made smaller for size reduction, a resin slider can be made asymmetric to have a thin wall section on the inner side of the downward edge of the lower rail and a thick wall section on the outer side. In the case of such asymmetric resin sliders, the error of mistaking a resin slider for the right side for a resin slider for the left side can cause defects seriously affecting the sliding motion of an upper rail. When asymmetrical resin sliders of a single kind are used for the left and right sides, similar troubles can arise if the front and rear ends of a resin slider are placed oppositely by mistake. Once a resin slider is attached, removal of the resin slider is not possible without breaking its hook portion. Therefore, a setup error of a resin slider increases the production cost. Means for preventing mistaken setup, such as a projection or a tape on a resin slider for indicating the orientation by the sense of touch or sight would increase the production cost by the need for addition production steps. The use of resin sliders of two different kinds for the left side and the right side requires two different metal molds or dies for forming two different sliders.  
           [0006]    It is, therefore, an object of the present invention to provide a resin slider, and a seat sliding apparatus or mechanism including resin sliders which are designed to facilitate assembly process and preventing mistaken setup.  
           [0007]    A seat sliding apparatus comprises at least one rail pair of first and second rails engaged with each other so that one is slidable on the other, and first and second resin sliders interposed between the first and second rails. Each of the first and second rails extends longitudinally from a first longitudinal rail end (such as a front or rear end) to a second longitudinal rail end (such as a rear or front end) along each other. One of the first and second rails is a lower rail to be fixed to a vehicle body, and the other is an upper rail to be fixed to a seat. The first rail comprises first and second side portions, such as flanges or edges, each extending along the first rail and each comprising first and second unequal engaging holes spaced from each other along the first rail. The first engaging hole is located in front of the second engaging hole in the first side portion whereas, in the second side portion, the second engaging hole is located in front of the first engaging hole.  
           [0008]    The first and second resin sliders are attached, respectively, to first and second side portions of the first rail. Each of the first and second resin sliders comprises first and second unequal engaging portions spaced along the first rail, and engaged, respectively, with the first and second engaging holes of one of the first and second side portions. The first engaging portion in the first resin slider is located in front of the second engaging portion along the first rail whereas, in the second resin slider, the second engaging portion is located in front of the first engaging portion along the first rail. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a sectional view of a lower rail and an upper rail in a seat sliding apparatus according to the embodiment of the present invention.  
         [0010]    [0010]FIG. 2 is a sectional view taken along line “II-II” of FIG. 1.  
         [0011]    [0011]FIG. 3 is a plan view of the lower rail and the upper rail of FIG. 1.  
         [0012]    [0012]FIG. 4 is a side view of the lower rail and the upper rail of FIG. 1.  
         [0013]    [0013]FIG. 5A is a plan view showing one of the resin sliders in the seat sliding apparatus of FIG. 1.  
         [0014]    [0014]FIG. 5B is a front view of the resin slider of FIG. 5A.  
         [0015]    [0015]FIG. 6A is an enlarged plan view showing one end portion of the resin slider of FIGS. 5A and 5B.  
         [0016]    [0016]FIG. 6B is an enlarged plan view showing the other end portion of the resin slider of FIGS. 5A and 5B.  
         [0017]    [0017]FIG. 6C is an enlarged front view showing the end portion of FIG. 6B.  
         [0018]    [0018]FIG. 7 is a sectional view of a lower rail and an upper rail in a seat sliding apparatus of earlier technology.  
         [0019]    [0019]FIG. 8 is a sectional view taken along line “VIII-VIII” of FIG. 7.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    FIGS.  1 ˜ 4  show one of left and right side rail pairs each including a lower rail  1  and an upper rail  3 . The lower rail  1  in this example as shown in FIG. 1 is a long panel or sheet member shaped to have a channel-shaped cross section. The lower rail  1  has left and right side inward flanges  1   a  bent inward toward each other. A plurality of rollers  2  are placed on a bottom wall of the lower rail  1  between left and right upright walls. The rollers  2  facilitate the sliding motion of the upper rail  3  by rolling on the bottom wall in the lower rail  1 . The upper rail  3  is a long panel or sheet member shaped to have a U-shaped cross section in an inverted posture. The upper rail  3  has left and right vertical walls disposed between the left and right inward flanges  1   a  of the lower rail  1 , and left and right outward flanges  3   a  bent outward under the left and right inward flanges  1   a  of the lower rail  1  so that the upper rail  3  is engaged with the lower rail  1 . Each of the left and right side outward flanges  3   a  has a lower flat portion for rolling on the rollers  2 , and an upward bent edge. Each of the left and right side inward flanges  1   a  of the lower rail  1  has an upper flat portion and the downward bent edge. On each of the left and right sides, the downward edge of the inward flange  1   a  of the lower rail  1  is located between the adjacent vertical wall and the upward edge of the outward flange  3   a  of the upper rail  3 .  
         [0021]    Left and right resin sliders  4  in this example are long members of resin attached to the downward edges of the left and right inward flanges  1   a  of the lower rail  1 , respectively. Each resin slider  4  has a thick upright wall section, a thin upright wall and a lower portion connecting the lower ends of the thick and thin upright wall sections so as to form a generally U-shaped cross section. The thin upright wall section is disposed between the downward edge of the inward flange  1   a  of the lower rail  1  and the adjacent upright side wall of the upper rail  3 . The thick upright wall section of the resin slider  4  is disposed between the downward edge of the inward flange  1   a  of the lower rail  1  and the upward edge of the outward flange  3   a  of the upper rail  3 . As viewed in FIG. 1, the thin wall sections of the left and right resin sliders  4  are placed between the thick wall sections of the left and right resin sliders  4 . Both (front and rear) ends of each resin slider  4  are closed.  
         [0022]    As shown in FIG. 2, each resin slider  4  extends longitudinally from a first longitudinal end to a second longitudinal end, and has large and small engaging portions  7   a  and  7   b  formed near the first and second longitudinal ends, respectively. As shown in FIGS. 5A and 5B, the large engaging portion  7   a  includes two large hook portions  8 , and the small engaging portion  7   b  includes two small hook portions  9 . As shown in FIGS. 6A, 6B and  6 C, in this example, the difference between the large hook portions  8  and the small hook portions  9  resides only in the difference in width. The width L 1  of the large hook portions  8 , as measured along the longitudinal direction of the resin slider  4 , is greater than the width L 2  of the small hook portions  9 . The large and small hook portions  8  and  9  are substantially identical in shape as shown in FIG. 1. Each resin slider  4  has a groove  12  extending longitudinally between the first and second longitudinal ends. In each of the large and small engaging portions  7   a  and  7   b , the large or small hook portions  8  or  9  are two confronting rectangular projections projecting toward each other from the opposite upright wall sections in the groove  12 .  
         [0023]    Each of the left and right inward flanges  1   a  of the lower rail  1  extends longitudinally from a first longitudinal end of the lower rail to a second longitudinal end, and each (left or right) inward flange  1   a  has large and small engaging holes  10  and  11  corresponding to the large and small engaging portions  7   a  and  7   b . The large and small engaging holes  10  and  11  are, respectively, formed in the vicinity of the first and second longitudinal ends of the lower rail  1 . The difference between the large and small engaging holes  10  and  11  resides only in the size. The large engaging hole  10  has a width (or dimension along the longitudinal direction) for snugly receiving the large hook portions  8  having the width L 1 . The small engaging hole  11  has a width for snugly receiving the small hook portions  9  having the width L 2 .  
         [0024]    As shown in FIG. 3, the large and small engaging holes  10  and  11  are formed, near the first longitudinal end of the lower rail  1 , respectively, in the left and right side inward flanges  1   a . The small and large engaging holes  11  and  10  are formed, near the second longitudinal end of the lower rail  1 , respectively, in the left and right side inward flanges  1   a . The two large engaging holes  10  and the two small engaging holes  11  are arranged at the four vertexes of a rectangle in a manner of central symmetry about the center of symmetry located at the middle of a center line of the lower rail  1  between the first and second longitudinal ends. The two large engaging portions  10  are arranged at diagonally opposite positions, and the two small engaging portions  11  are arranged at diagonally opposite positions. One of the left and right inward flanges  1   a  has the large engaging portion  10  near the front longitudinal end of the lower rail  1 , and the small engaging portion  11  near the rear longitudinal end of the lower rail  1 , whereas the other of the left and right inward flanges  1   a  has the small engaging portion  11  near the front longitudinal end of the lower rail  1 , and the large engaging portion  11  near the rear longitudinal end of the lower rail  1 .  
         [0025]    One resin slider  4  is attached to one of the left and right inward flanges  1   a  of the lower rail  1  by pushing the resin slider  4  to insert the downward edge of the inward flange  1   a  into the groove  12  of the resin slider  4 . In this case, the large and small hook portions  8  and  9  of the resin slider  4  are fit, respectively, into the large and small engaging holes  10  and  11 , and the resin slider  4  is secured to the inward flange  1   a  correctly. If the resin slider  4  is pushed in such a wrong manner that the large hook portions  8  are set to the small engaging hole  10  and the small hook portions  9  are set to the large engaging hole  11 , then the large hook portions  8  can not fit into the small engaging hole  11  though the small hook portions  9  can fit into the large engaging hole  10 . Therefore, the arrangement of this embodiment can reliably prevent wrong setting of a resin slider, facilitate the assembly process, and ensure correct setting in which the thin wall section of the resin slider is on the correct side.  
         [0026]    Thereafter, another resin slider  4  is attached to the other of the left and right inward flanges  1   a  of the lower rail  1  by turning the resin slider  4  around and pushing the resin slider  4  to insert the edge of the inward flange  1   a  into the groove  12 . The large and small hook portions  8  and  9  of the resin slider  4  are correctly engaged into the large and small engaging holes  10  and  11  when the resin slider  4  is turned around correctly.  
         [0027]    Thus, the seat slide structure according to the embodiment of the present invention eliminates the need for resin sliders of two different kinds. Resin sliders needed in the embodiment are of one and the same kind.  
         [0028]    The diagonally opposite arrangement of the large and small engaging holes  10  and  11  ensures the correct setup of two resin sliders in which the large engaging hole  10  of a first resin slider, and the small engaging hole  11  of a second resin slider are paired near the front end of the lower rail, and the small engaging hole  11  of the first resin slider, and the large engaging hole  10  of the second resin slider are paired near the rear end of the lower rail.  
         [0029]    In the illustrated embodiment, the resin sliders  4  are attached to the lower rails  1 . However, the present invention is not limited to this. Resin sliders  4  may be attached to upper rails  3 .  
         [0030]    Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. The scope of the invention is defined with reference to the following claims.