Abstract:
A vehicle body ( 12 ) includes: a coupling recess ( 35 ) that couples an outer bottom member ( 42 ) with an outer top member ( 41 ) of an outer panel ( 37 ) of a vehicle body pillar ( 21 ); and a door seal cover ( 34 ) that covers the coupling recess ( 35 ). The door seal cover ( 34 ) comprises: a U-shaped body part ( 43 ) that has a U-shaped cross section and serves as a central portion; a U-shaped top lip ( 44 ) that extends upward from the body part ( 43 ); and a U-shaped bottom lip ( 45 ) that extends downward from the body part ( 43 ). A front top leading end ( 57 ), a front bottom leading end ( 58 ), a back top leading end ( 61 ), and a back bottom leading end ( 32 ) of seal contact surface sections ( 51, 54 ), which are firmly attached to door-side seal members ( 48, 49 ), are formed at step-free thicknesses.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a vehicle body side structure including a door seal cover for covering a coupling portion on a surface of a vehicle formed by coupling a plurality of outer panels. 
       BACKGROUND ART 
       [0002]    Among vehicle body side structures, there is a structure for coupling a portion extending from a roof to an upper portion of a center pillar (see Patent Literature 1, for example). A center pillar is plastically formed as a separate body by using a high tension steel plate, a roof rail is plastically formed by using a normal steel plate, and a vehicle body outer panel coupling portion couples the center pillar and the roof rail near the roof rail. In a vehicle body in which the coupled portions are covered, respective pillars such as a center pillar are divided into upper and lower two portions. Step portions are formed at boundary portions where the upper portions and the lower portions are coupled and seal tape is stuck to the step portion, with which a seal member provided to a door comes in contact, out of the step portions (see Patent Literature 2, for example). 
         [0003]    However, an outward appearance of the vehicle body outer panel coupling portion disclosed in Patent Literature I is not good, because a step is formed by a plate material laid on the coupling portion between the upper portion of the center pillar and the roof rail or a welding mark remains. 
         [0004]    In the side structure disclosed in Patent Literature 2, the seal tape is stuck only to a position corresponding to the seal member provided to the door and therefore seal tape does not exist at the remaining step portions. In this manner, the step portions formed at the coupling portions are exposed and remain, which detracts from the appearance. If large seal tape adapted to the remaining step portions is used to cover the remaining step portions, a thin edge of the seal tape (door seal cover) corrugates and it is difficult to carry out the operation. Moreover, the thin edge of the seal tape (door seal cover) may not uniformly come in contact, which detracts from appearance. 
       PRIOR ART LITERATURE 
     Patent Literature 
       [0005]    Patent Literature 1: JP 2011-195107 A 
         [0006]    Patent Literature 2: JP 2011-88494 A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    It is an object of the present invention to provide a vehicle body side which facilitates a mounting operation of a door seal cover for covering a coupling recessed portion and improves appearance of the mounted door seal cover. 
       Solution to Problem 
       [0008]    According to a first aspect of the present invention, there is provided a vehicle body side structure in which an outer panel, forming an outer face, of a vehicle body pillar supporting a roof of a vehicle body is formed by coupling an outer lower member to an outer upper member, the vehicle body side structure including: a coupling recessed portion where the outer lower member is coupled to the outer upper member; and a door seal cover for covering the coupling recessed portion, wherein the door seal cover has a U-shaped section and includes a U-shaped body at a central portion, a U-shaped upper lip extending upward from the body portion, and a U-shaped lower lip extending downward from the body portion, the upper lip and the lower lip have tip ends to he respectively laid on the outer upper member and the outer lower member, of the tip ends, tip end portions of seal close contact face portions to be held in close contact with door-side seal members of a door of the vehicle body are formed to have a non-stepped thickness so as to prevent the door-side seal member from separating from the outer upper member and the outer lower member while remaining tip end portions are formed to have a stepped thickness. 
         [0009]    In a second aspect of the invention, preferably, the outer panel has a U-shaped section and the upper lip and the lower lip have thicknesses gradually reducing from the body portion toward the tip ends. 
         [0010]    In a third aspect of the invention, preferably, the remaining tip end includes a gradually changing tip end thickness portion having a thickness gradually increasing in a direction away from the tip end of the seal close contact face portion and a constant tip end thickness portion. continuous with the gradually changing tip end thickness portion and having a constant thickness. 
         [0011]    In a fourth aspect of the invention, preferably, the door seal cover has a front end and a rear end continuous with the tip end of the upper lip and continuous with the tip end of the lower lip, the front end and the rear end covered with respective door opening seals provided to a front door opening edge and a rear door opening edge of the vehicle body. 
         [0012]    In a fifth aspect of the invention, preferably, the upper lip and the lower lip have seal outer wall thickness adjusting areas continuous with the seal close contact face portion, each of the seal outer wall thickness adjusting areas has a gradually changing wall thickness portion having a wall thickness gradually increasing in a direction away from the seal close contact face portion and toward the body portion and an intermediate gradually changing wall thickness portion continuous with the gradually changing wall thickness portion and having a wall thickness gradually increasing toward the body portion, and the gradually changing wall thickness portion has a boundary portion with the seal close contact. face portion, the boundary portion forming a triangular area substantially orthogonal to the tip end. 
       Advantageous Effects of Invention 
       [0013]    In the first aspect of the invention, when the door seal cover is mounted to the outer panel in order to cover the coupling recessed portion with the door seal cover, the tip ends for coming in contact with the outer panel are not entangled and it is possible to prevent the entanglement. In other words, a mounting operation of the door seal cover becomes easy. 
         [0014]    Moreover, because the remaining tip end has such a thickness as to form the step, rigidity of the door seal cover increases to thereby prevent corrugating deformation of the tip end of the seal close contact face portion after the door seal cover is taken out of a die for molding resin. As a result, the corrugating deformation of the tip end of the seal close contact face portion does not occur when the door seal cover is mounted to the vehicle body pillar, which improves an appearance. 
         [0015]    In the second aspect of the invention, the outer panel has the U-shape section and the upper lip and the lower lip have thicknesses gradually reducing from the body portion toward the tip ends. Therefore, the thickness is the largest at the body portion and gradually reduces in directions away from the body portion, only the tip end of the seal close contact face portion has the thickness without the step, and it is possible to secure rigidity of the door seal cover. As a result, it is possible to maintain the U-shaped section, which facilitates the operation for setting the door seal cover on the U-shaped outer panel. 
         [0016]    In the third aspect of the invention, the remaining tip end includes the gradually changing tip end thickness portion having a thickness gradually increasing in a. direction away from the tip end of the seal close contact face portion and the constant tip end thickness portion continuous with the gradually changing tip end thickness portion and having the constant thickness. Therefore, the thicknesses of the tip ends of the door seal cover change smoothly from the tip end having the thickness without the step to the constant tip end thickness portion and the thicknesses of the tip ends look uniform, which improves appearances of the tip ends and areas around the tip ends. 
         [0017]    In the fourth aspect of the invention, the door seal cover has the front end and the rear end continuous with the tip end of the upper lip and continuous with the tip end of the lower lip, the front end and the rear end covered with the respective door opening seals provided to the front door opening edge and the rear door opening edge of the vehicle body side portion. Therefore, it is possible to suppress falling off of the door seal cover from the vehicle body pillar. Moreover, the front end and the rear end are hidden by the door opening seals, which improves the appearance. 
         [0018]    In the fifth aspect of the invention, the upper lip and the lower lip have seal outer wall thickness adjusting areas continuous with the seal close contact face portion. Each of the seal outer wall thickness adjusting areas has the gradually changing wall thickness portion having a wall thickness gradually increasing in the direction away from the seal close contact face portion and toward the body portion and the intermediate gradually changing wall thickness portion continuous with the gradually changing wall thickness portion and having the wall thickness gradually increasing toward the body portion. The gradually changing wall thickness portion has the boundary portion with the seal close contact face portion and the boundary portion forms the triangular area substantially orthogonal to the tip end. Therefore, the door seal cover has a smooth outer face and the appearance is further improved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  is a side view illustrating a vehicle body employing a vehicle body side structure according to an embodiment of the present invention: 
           [0020]      FIG. 2  is an enlarged view illustrating region  2  of FIG.  1 .; 
           [0021]      FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2 ; 
           [0022]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2 ; 
           [0023]      FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 2 ; 
           [0024]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 2 ; 
           [0025]      FIG. 7  is a perspective view illustrating a door seal cover according to the present embodiment; 
           [0026]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 7 ; and 
           [0027]      FIG. 9  is a schematic view illustrating the door seal cover in a mounted state. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. 
       Embodiment 
       [0029]    As illustrated in  FIGS. 1 and 2 , a vehicle body  12  employs a vehicle body side structure according to the present embodiment. A side body  13  includes a side sill  17  forming an end portion of a floor (underbody)  16  of a vehicle interior  15 , a front pillar  18  rising from the side sill  17 , a center pillar  21 , and a rear pillar  22  and supports a roof  23 . 
         [0030]    The vehicle body  12  has a front door opening portion  25  formed by the front pillar  18  and the center pillar  21  and a rear door opening portion  26  formed by the center pillar  21  and the rear pillar  22 . 
         [0031]    To the front door opening portion  25 , a front door  28  and a. front door opening seal  31  are mounted. To the rear door opening portion  26 , a rear door  32  and a rear door opening seal  33  are mounted. 
         [0032]    In the side body  13  according to the embodiment, a door seal cover  34  is mounted to the center pillar  21  to cover a coupling recessed portion  35  (refer to  FIG. 9  as well). 
         [0033]    Next, a structure of the vehicle body side structure according to the embodiment will be described. As illustrated in  FIG. 2 , an outer panel  37  forming an outer face  36  of the center pillar  21  supporting the roof  23  of the vehicle body  12  is formed by connecting an outer lower member  42  to an outer upper member  41 . 
         [0034]    The side body  13  includes the coupling recessed portion  35  where the outer lower member  42  is connected to the outer upper member  41  and the door seal cover  34  for covering the coupling recessed portion  35 . 
         [0035]    As illustrated in  FIGS. 3 to 7 , the door seal cover  34  has a U-shaped section and includes a body portion  43  having a U-shaped central portion ( FIG. 7 ), a U-shaped upper lip  44  extending upward from the body portion  43 , and a U-shaped lower lip  45  extending downward from the body portion  43 . 
         [0036]    As illustrated in  FIG. 7 , the upper lip  44  and the lower lip  45  respectively have tip end portions  46  and  47  to be laid on the outer upper member  41  and the outer lower member  42 . Tip ends (a front upper tip end  57 , a front lower tip end  58 , a rear upper tip end  61 , and a rear lower tip end  62 ) of seal close contact face portions  51  (a front upper seal close contact face portion  52 , a front lower seal close contact face portion  53 ) ( FIG. 7 ) and seal close contact face portions  54  (a rear upper seal close contact face portion  55  and a rear lower seal close contact face portion  56 ) to be in close contact with door-side seal members  48  and  49  ( FIGS. 3 and 4 ) of the doors (the front door  28 , the rear door  32 ) of the side body  13  are formed to have thicknesses without steps to prevent the door-side seal members  48  and  49  from separating from the outer upper member  41  and the outer lower member  42  (see  FIG. 5 ). 
         [0037]    Remaining tip ends  64 ,  65 , and  66  illustrated in  FIG. 7  have thicknesses t (e.g., 0.5 mm) to form steps as illustrated in  FIG. 6 . As illustrated in  FIGS. 7 and 9 , the seal close contact face portions  51  and  54  are illustrated with dotted patterns. 
         [0038]    As illustrated in  FIG. 3 , the outer panel  37  has a U-shaped section, As illustrated in  FIG. 5 , thicknesses of the upper lip  44  and the lower lip  45  gradually reduce from the body portion  43  toward the tip ends  46  and  47 . 
         [0039]    The remaining tip ends  64 ,  65 , and  66  illustrated in  FIG. 7  have gradually changing tip end thickness portions  67 ,  71 ,  72 , and  73  having thicknesses gradually increasing in directions (directions of arrows a1 to a4) away from the tip ends (the front upper tip end  57 , the front lower tip end  58 , the rear upper tip end  61 , and the rear lower tip end  62 ) of the seal close contact face portions  51  (the front upper seal close contact face portion  52  and the front lower seal close contact face portion  53 ) and the seal close contact face portions  54  (the rear upper seal close contact. face portion  55  and the rear lower seal close contact face portion  56 ) and constant tip end thickness portions  74 ,  75 , and  76  continuous with the gradually changing tip end thickness portions  67 ,  71 ,  72 , and  73  and having constant thicknesses. In  FIG. 7 , the gradually changing tip end thickness portions  67 ,  71 ,  72 , and  73  are illustrated with vertical striped patterns. 
         [0040]    The door seal cover  34  has a front end  77  and a rear end  78  continuous with a tip end  46  of the upper lip  44  and continuous with a tip end  47  of the lower lip  45  and the front end  77  and the rear end  78  are covered with respective door opening seals (a front door opening seal  31  and a rear door opening seal  33 ) provided to a front door opening edge  81  ( FIGS. 2 ,  3 , and  4 ) and a rear door opening edge  82  of the side body  13  ( FIGS. 3 and 4 ). The front door opening seal  31  and the rear door opening seal  33  covering the front end  77  and the rear end  78  extend in a vertical direction of the side body  13 . 
         [0041]    As illustrated in  FIGS. 7 and 8 , the upper lip  44  and the lower lip  45  have seal outer wall thickness adjusting areas  83 ,  84 ,  85 , and  86  (illustrated with vertical hatching) continuous with the seal close contact face portions  51  (the front upper seal close contact face portion  52  and the front lower seal close contact face portion  53 ) and the seal close contact face portions  54  (the rear upper seal close contact face portion  55  and the rear lower seal close contact face portion  56 ). 
         [0042]    The seal outer wall thickness adjusting areas  83 ,  84 ,  85 , and  86  have gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  (illustrated with vertical hatching) having wail thicknesses gradually increasing in directions (directions of arrows a1 to a4) away from the seal close contact face portions  51  (the front upper seal close contact face portion  52  and the front lower seal close contact face portion  53 ) and the seal close contact face portions  54  (the rear upper seal close contact face portion  55  and the rear lower seal close contact face portion  56 ) and toward the body portion  43  and intermediate gradually changing wall thickness portions  95 ,  96 , and  97  (illustrated with horizontal hatching) continuous with the gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  and having wall thicknesses gradually increasing toward the body portion  43 . 
         [0043]    The gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  (illustrated with the vertical hatching) have boundary portions  98  with the seal close contact face portions  51  and  54  and the boundary portions  98  form triangular areas (illustrated with the vertical hatching) substantially orthogonal to the tip ends  46  and  47 . 
         [0044]    Next, the outer panel  37  of the center pillar  21  and the door seal cover  34  will be described in detail. 
         [0045]    As illustrated in  FIGS. 3 and 4 , the center pillar  21  includes the outer panel  37  and an inner panel  101  and these panels  37  and  101  form a closed sectional shape. The inner panel  101  has a hat-shaped section with flanges  102  and the flanges  102  are coupled to the outer panel  37  with an opening  103  facing the outer panel  37 . 
         [0046]    The outer panel  37  has a hat-shaped section with a flange  105 . The outer panel  37  includes a body wall portion  106 , a front wall portion  107  continuous with the body wall portion  106 , a rear wall portion  108  continuous with the body wall portion  106 , and the flange  105 . The flange  105  includes a front flange  105   a  and a rear flange  105   b.    
         [0047]    The front flange  105   a  has the front door opening edge  81  of the front door opening portion  25  and the front door opening seal  31  is mounted to the front flange  105   a.  The front door opening seal  31  has a grasping portion  111  at the front door opening edge  81  and a bulging close contact portion  112  formed to be continuous with the grasping portion  111  and comes in close contact with the front door  28 . The bulging close contact portion  112  comes in contact with the front end  77  of the door seal cover  34  mounted to the outer panel  37  in such a manner as to hide the front end  77 . 
         [0048]    The rear flange  105   b  has the rear door opening edge  82  of the rear door opening portion  26  and the rear door opening seal  33  is mounted to the rear flange  105   b.  The rear door opening seal  33  has a grasping portion  114  at the rear door opening edge  82  and a bulging close contact portion  115  formed to he continuous with the grasping portion  114  and comes in close contact with the rear door  32 . The bulging close contact portion  115  comes in contact with the rear end  78  of the door seal cover  34  mounted to the outer panel  37  in such a manner as to hide the rear end  78 . 
         [0049]    As is already described, the outer panel  37  has the outer upper member  41  from which the outer lower member  42  continues. As illustrated in  FIGS. 3 to 6 , the outer upper member  41  has an upper joint portion  117  deformed by deforming a lower portion of the outer upper member  41  toward the vehicle interior (arrow a6). At the upper joint portion  117 , the body wall portion  106  is deformed distance a toward the vehicle interior (arrow a6). The outer lower member  42  has a lower joint portion  118  formed by deforming an upper portion of the outer lower member  42  toward the vehicle interior (arrow a6). At the lower joint portion  118 , the body wall portion  106  is deformed distance  3  toward the vehicle interior (arrow a6). 
         [0050]    By laying the upper joint, portion  117  on the lower joint, portion  118  and coupling them, the coupling recessed portion  35  is formed. The door seal cover  34  is stuck to the upper joint, portion  117  of the coupling recessed portion  35  by using double-sided tape  121 . 
         [0051]    As illustrated in  FIGS. 5 to 8 , the door seal cover  34  includes the body portion  43 , the upper lip  44 , and the lower lip  45 . The upper lip  44  and the lower lip  45  are substantially symmetric about a center (a center line  122  of  FIG. 7 ) of the body portion  43 . 
         [0052]    As illustrated in  FIG. 7 , the upper lip  44  includes the front upper seal close contact face portion  52 , the rear upper seal close contact face portion  55 , the gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  (vertical hatching), and the intermediate gradually changing wall thickness portions  95 ,  96 , and  97  (horizontal hatching). 
         [0053]    The gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  form the triangular areas. The intermediate gradually changing wall thickness portions  95  and  97  form the substantially triangular areas. The intermediate gradually changing wall thickness portion  96  has a triangular area and forms an area formed by combining the triangular shapes and the rectangular shape. 
         [0054]    The front upper seal close contact face portion  52  and the rear upper seal close contact face portion  55  have thicknesses gradually increasing toward the body portion  43 . For example, the thickness gradually increases from the tip end  57  having such a thickness as to be able to secure watertightness which is an extremely small thickness (substantially close to 0 mm) to the body portion  43  having a thickness of 2 mm ( FIG. 5 ). A boundary portion  124  between the gradually changing wall thickness portion  92  and the intermediate gradually changing wall thickness portion  96  has a thickness gradually increasing toward the body portion  43 . For example, the thickness gradually increases from the tip end  46  of the intermediate gradually changing wall thickness portion  96  having a thickness of 0.5 mm to the body portion  43  having a thickness of 2 mm. 
         [0055]    Boundary portions  125 ,  126 , and  127  between the gradually changing wall thickness portions  91 ,  93 , and  94  and the intermediate gradually changing wall thickness portions  95 ,  96 , and  97  have thicknesses gradually increasing from 0.5 mm to the body portion  43  having the thickness of 2 mm similarly to the boundary portion  124 . 
         [0056]    The intermediate gradually changing wall thickness portions  95 ,  96 , and  97  have thicknesses changing from the tip end  46  having the thickness of 0.5 mm to the body portion  43  having the thickness of 2 mm. The lower lip  45  has the same structure as the upper lip  44 . 
         [0057]    Next, a mounting procedure of the door seal cover  34  will be briefly described and a function of the door seal cover  34  will be described. 
         [0058]    As illustrated in  FIG. 9 , when the door seal cover  34  is mounted to the outer panel  37  of the vehicle body pillar  21  in a direction of an arrow b1, the tip ends (the remaining tip ends ( 34  and  66 ) near the front end  77  and the rear end  78  of the door seal cover  34  are not entangled in directions of arrows b2 and b3. 
         [0059]    In other words, because only the tip ends (the front upper tip end  57 , the front lower tip end  58 , the rear upper tip end  61 , and the rear lower tip end  62 ) of the seal close contact face portions  51  (the front upper seal close contact face portion  52  and the front lower seal close contact face portion  53 ) and the seal close contact face portions  54  (the rear upper seal close contact face portion  55  and the rear lower seal close contact face portion  56 ) illustrated in  FIG. 7  have thicknesses (e.g., thicknesses of 0.1 mm) without steps and the other portions (the gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  and the intermediate gradually changing wall thickness portions  95 ,  96 , and  97 ) illustrated in  FIG. 7  are formed to he thick-walled, the tip ends (the remaining tip ends  64  and  66 ) are not deformed and entangled when the door seal cover  34  comes in contact with the outer panel  37 . 
         [0060]    Furthermore, because the other portions (the gradually changing wall thickness portions  91 ,  92 ,  93 , and  94  and the intermediate gradually changing wall thickness portions  95 ,  96 , and  97 ) illustrated in  FIG. 7  are thick-walled, the door seal cover  34  can be maintained in the U-shape, which facilitates a mounting operation for mounting the door seal cover  34  to the outer panel  37 , having the U-shaped section, of the vehicle body pillar  21 . 
         [0061]    The remaining tip ends  64 ,  65 , and  66  illustrated in  FIG. 7  include the gradually changing tip end thickness portions  67 ,  71 ,  72 , and  73  having the thicknesses gradually increasing in the directions away from the tip ends (the front upper tip end  57 , the front lower tip end  58 , the rear upper tip end  61 , and the rear lower tip end  62 ) of the seal close contact face portions  51  and  54  and the constant tip end thickness portions  74 ,  75 , and  76  continuous with the gradually changing tip end thickness portions  67 ,  71 ,  72 , and  73  and having constant thicknesses. Therefore, the thicknesses of the tip ends  46  and  47  of the door seal cover change smoothly from the tip ends (the front upper tip end  57 , the front lower tip end  58 , the rear upper tip end  61 , and the rear lower tip end  62 ) having the thicknesses without steps to the constant tip end thickness portions  74 ,  75 , and  76  and the thicknesses of the tip ends  46  and  47  look uniform, which improves appearances of the tip ends  46  and  47  and areas around the tip ends  46  and  47 . 
       INDUSTRIAL APPLICABILITY 
       [0062]    The vehicle body side structure according to the invention is suitable for use on automobiles. 
       REFERENCE SIGNS LIST 
       [0063]      12  . . . vehicle body,  13  . . . vehicle body side portion,  21  . . . vehicle body pillar,  23  . . . roof,  28  front door,  31  . . . door opening seal (front door opening seal),  32  . . . rear door,  33  door opening seal (rear door opening seal),  34  . . . door seal cover,  35  coupling recessed portion,  36  outer face of vehicle body pillar,  37  outer panel,  41  . . . outer upper member,  42  . . . outer lower member, body portion,  44  . . . upper lip,  45  . . . lower lip,  46  . . . tip end of upper lip,  47  . . . tip end of lower lip,  48 ,  49  . . . door-side seal member,  51 ,  54  . . . seal close contact face portion . . .  57  tip end of seal close contact face portion (front upper tip end),  58  . . . tip end of seal close contact face portion (front lower tip end),  61  . . . tip end of seal close contact face portion (rear upper tip end),  62  . . . tip end of seal close contact face portion (rear lower tip end),  64 ,  65 ,  66  . . . remaining tip end,  67 ,  71 ,  72 ,  73  gradually changing tip end thickness portion,  74 ,  75 ,  76  . . . constant tip end thickness portion,  77  . . . front end,  78  . . . rear end,  81  . . . front door opening edge,  82  . . . rear door opening edge,  83 ,  84 ,  85 ,  86  . . . seal outer wall thickness adjusting area,  91 ,  92 ,  93 ,  94  . . . gradually changing wail thickness portion,  95 ,  96 ,  97  . . . intermediate gradually changing wall thickness portion,  98  . . . boundary portion