Abstract:
Disclosed is a vehicle chassis side structure comprising a side sill ( 15 ) whereupon a closed section is formed from a side sill outer ( 37 ) and a side sill inner ( 38 ). The side sill outer ( 37 ) comprises an upper wall portion ( 44 ) and a lower wall portion ( 45 ). The closed section is formed in a polygonal shape by forming an upper bead ( 47 ) from the leading end of the side sill ( 15 ) to the trailing end thereof, upon at least the upper wall portion ( 44 ) from among the upper and lower wall portions ( 44, 45 ). The vehicle chassis side structure further comprises a reinforcement member ( 64 ) upon a central joining portion ( 56 ) whereat a center pillar ( 17 ) is joined, which closes an opening ( 61 ) of the upper bead ( 47 ) and an opening ( 62 ) of a lower bead ( 48 ), forming the closed section.

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle body side part structure including a side sill forming a bottom frame of a vehicle doorway, and a front pillar and a center pillar forming a vertical frame of the vehicle doorway, the side sill being joined to the front and center pillars. 
     BACKGROUND ART 
     Patent Literature 1 filed by the present assignee discloses a vehicle body side part structure in which a center pillar is jointed to a side sill, and an inner member of the center pillar, which faces a passenger compartment, is extended downward such that an opening of an upper groove-shaped bead formed on the side sill is closed by the downward extension of the inner member. 
     In the vehicle body side part structure of Patent Literature 1, however, the center pillar&#39;s inner member needs to provide an extension for exclusive purpose of closing the opening of the upper bead of the side sill, thus adding further complexity to the center pillar structure. 
     Consequently, when used with a center pillar of normal design, the side sill is required to provide an increased mechanical strength in a middle section thereof where the center pillar is to be joined. 
     A similar problem has been experienced at a front section of the side sill to which the front pillar is jointed. 
     PRIOR ART LITERATURE 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application No. 2009-176856 
     SUMMARY OF INVENTION 
     Technical Problem 
     An object of the present invention is to provide a vehicle body side part structure including a side sill having an increased strength both at central and front parts thereof where a center pillar and a front pillar are joined to the side sill. 
     Solution to Problem 
     According to one aspect of the present invention, there is provided a vehicle body side part structure comprising: a side sill disposed on right and left sides of a floor of a vehicle body and extending in a longitudinal direction of the vehicle body; a front pillar extending from a front part of the side sill to a roof; and a center pillar extending from a central part of the side sill to the roof, wherein the side sill is formed of an outer side sill member and an inner side sill member, the outer and inner side sill members jointly defining a closed cross section extending in the longitudinal direction of the vehicle body; wherein the outer side sill member includes an upper wall extending to slant upwardly from a vehicle exterior side toward a vehicle interior side and a lower wall extending to slant downwardly from the vehicle exterior side toward the vehicle interior side, at least one of the upper and lower walls having a bead extending from a front end of the side sill to a rear end thereof such that the closed cross section is formed in a polygonal shape, wherein the bead is a recessed portion indented inwardly of the closed cross section and including lateral walls and a bottom wall formed integrally with the lateral walls, and the bottom wall has a width greater than a height of the lateral walls, wherein the central part of the side sill has a central joining portion where the center pillar is joined to the side sill, the front part of the side sill has a front joining portion where the front pillar is joined to the side sill, and at least one of the central and front joining portions is provided with a reinforcement member, the reinforcement member being positioned to close an opening of the bead to define a second closed cross section jointly with the bead. 
     Preferably, the outer side sill member includes a vertical wall connected between the upper wall and the lower wall and located on the vehicle exterior side, and a lateral bead formed on the vertical wall such that the closed cross section defined between the outer and inner side sill members is formed in a polygonal shape, and the reinforcement member is configured to close the opening of the bead and an opening of the lateral bead to form respective closed cross sections jointly with the beads. 
     Preferably, the reinforcement member has an elongated portion extending rearwardly of the vehicle body from the front joining portion of the side sill by a desired length. 
     Preferably, the reinforcement member has an elongated portion extending longitudinally in at least one of a forward direction and a rearward direction of the vehicle body from the central joining portion of the side sill by a desired length. 
     Preferably, the side sill includes a bulkhead disposed therein to partition an internal space of the side sill, the bulkhead being arranged to overlap the reinforcing member via the outer side sill member. 
     Preferably, the side sill includes a bulkhead disposed therein to partition an internal space of the side sill, and the reinforcement member is arranged to extend to such an extent that the reinforcement member overlaps the bulkhead in a widthwise direction of the vehicle. 
     Preferably, the bulkhead defines a closed cross section jointly with the outer side sill member. 
     Preferably, the bulkhead has an engagement recess fitted with a lateral bead formed on a vertical wall of the outer side sill member, a bottom of the engagement recess being in contact with a bottom wall of the lateral bead, and that part of the bulkhead which excludes the engagement recess is in contact with the vertical wall of the outer side sill member. 
     Advantageous Effects of Invention 
     When the reinforcement member is mounted on the central joining portion and thus interposed between the center pillar and the side sill, the bead communicating with the internal space of the center pillar of closed cross section is made to have a closed cross section by the reinforcement member. Thus the strength of the side sill is enhanced. 
     Similarly, when the reinforcement member is mounted on the front joining portion, the bead communicating with the internal space of the front pillar of closed cross section is made to have a closed cross section by the reinforcement member. Thus the strength of the side sill is enhanced. 
     The reinforcement member is configured to close the opening of the bead and the opening of the lateral bead to thereby define the respective closed cross sections jointly with the beads, thus enhancing the strength of the side sill. 
     The reinforcement member has an elongated portion extending from the front joining portion in a rearward direction of the vehicle by a desired length. Such arrangement enhances the strength of the side sill and enlarges, in the longitudinal direction of the vehicle, such an area of the side sill that endures a lateral collision load. 
     The reinforcement member may also have an elongated portion extending from the central joining portion in at least in one of a forward direction and a rearward direction of the vehicle by a desired length. Such arrangement enhances the strength of the side sill and enlarges, in the longitudinal direction of the vehicle, such an area of the side sill that endures a lateral collision load. 
     The bulkhead is arranged to overlap the reinforcement member with the outer side sill member interposed therebetween. Therefore a load applied to the reinforcement member is directly transmitted to the bulkhead, thus enhancing the strength of the side sill. 
     The reinforcement member extends to such an extent that the reinforcement member overlaps the bulkhead in a widthwise direction of the vehicle. Therefore, a load applied to the reinforcement member is directly transmitted to the bulkhead, thus enhancing the strength of the side sill. 
     The bulkhead is configured to define a closed cross section jointly with wall portions of the outer side sill member and respective lateral walls of the bead, thereby providing an increased number of closed cross sections of the side sill. As a result, the strength of the side sill is further enhanced. 
     In an assembled state, the engagement recess of the bulkhead is fitted with the lateral bead while the bottom of the engagement recess is in contact with the bottom wall of the lateral bead and that part of the bulkhead which excludes the engagement recess is in contact with the vertical wall of the outer side sill member. This arrangement limits an undesired inclination of the bulkhead, thereby advantageously facilitating the installation of the bulkhead onto outer side sill member. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a vehicle body provided with a vehicle body side part structure according to a first embodiment of the present invention; 
         FIG. 2  is a side elevational view showing the vehicle body side part structure according to the first embodiment of the present invention; 
         FIG. 3  is a perspective view of the first embodiment as viewed in the direction of arrow  3  in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 2 ; 
         FIG. 6  is a side elevational view showing a vehicle body side part structure according to a second embodiment of the present invention; 
         FIG. 7  is a perspective view of the vehicle body side part structure according to the second embodiment of the present invention; 
         FIG. 8  is a plan view of the vehicle body side part structure according to the second embodiment of the present invention; 
         FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 6 ; 
         FIG. 10  is a view showing a vehicle body side part structure according to a third embodiment of the present invention; 
         FIG. 11  is a perspective view illustrating a bulkhead shown in  FIG. 10 ; 
         FIG. 12  is a side elevational view showing a vehicle body side part structure according to a fourth embodiment of the present invention; 
         FIG. 13  is a cross-sectional view taken along line  13 - 13  of  FIG. 12 ; and 
         FIG. 14  is a side elevational view showing a vehicle body side part structure according to a fifth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Certain preferred embodiments of the present invention will be described below with reference to the attached drawings. 
     First Embodiment 
     A vehicle body front part structure according to a first embodiment of the present invention is implemented in a vehicle  12 , as shown in  FIG. 1 . The vehicle body side part structure is incorporated in a side body  14  consisting of a side wall of a passenger compartment  13  of the vehicle  12 , and includes a side sill  15  forming a lower part of the side body  14 , a front pillar  16  and a center pillar  17 . 
     As shown in  FIGS. 1 and 2 , a vehicle body  21  includes left and right side bodies  14 ,  14 , a roof  22  connected between upper parts of the side bodies  14 , an under body  23  connected between lower parts of the side bodies  14  and forming a floor of a passenger compartment  13 , and a front body  24  disposed forwardly and continuous to the compartment  13 . The front body  24  includes right and left front side frames  26 ,  26  extending from a vehicle front head  25  to the under body  23 . 
     The vehicle body side part structure is constructed such that the front pillar  16  is joined at a lower part  31  thereof to a front part  27  of the side sill  15 , and the center pillar  17  is joined at a lower part  35  thereof to a central part  33  of the side sill  15 . 
     Now substantial features of the vehicle body side part structure of the present invention will be described with reference to  FIGS. 1 to 5 . 
     The vehicle body side part structure includes the side sill  15 ,  15  disposed at right and left edges of the floor of the passenger compartment  13  and extending in a front-back or longitudinal direction (in a direction of axis X) of the vehicle  12 , the front pillar  16  extending vertically from the front part  27  of the side sill  15  to the roof  22 , and the center pillar  17  extending vertically from the central part of the side sill  15  to the roof  22 . 
     The side sill  15  includes an outer side sill member (a side sill outer)  37  and an inner side sill member (a side sill inner)  38  disposed such that both members jointly define a closed cross section as shown in  FIGS. 3 to 5 . As shown in  FIG. 4 , the outer side sill member  37  includes an upper wall  44  extending to slant upwardly (in a direction of arrow a 1 ) from a vehicle exterior side  41  toward a vehicle interior side  42 , and a lower wall  45  disposed opposite to the upper wall  44  and extending to slant downwardly (in a direction of arrow a 2 ) from the vehicle exterior side  41  toward the vehicle interior side  42 . At least the upper wall  44  of the upper and lower walls  44 ,  45  has a bead (upper bead)  47  formed to extend from the front part  27  to a rear part  47  of the side sill  15  so that the closed cross section of the side sill  15  is formed in a polygonal shape. 
     The lower wall  45  of the side sill  15  has a lower bead  48  formed to extend from the front part  27  to the rear part  46  of the side sill  15 . 
     Each of the upper and lower beads  47 ,  48  is a groove-shaped recessed portion indented inwardly (in a direction of arrow a 4 ) into the closed cross section as viewed from the exterior (in a direction of arrow a 3 ) of the side sill  15 . Each of the recessed portions includes a pair of lateral walls (groove side wall)  51 ,  52  and a bottom wall  53 ,  54 , thus providing an opening  61 ,  62  at an opposite side of the bottom walls  53 ,  54 , respectively. Namely, the upper and lower beads  47 ,  48  each have the opening  61 ,  62 , the pair of lateral walls  51 ,  52  and the bottom wall  53 ,  54 , thereby forming a substantial U-shape in cross section. It should be noted here that the respective bottom walls  53 ,  54  of the beads  47 ,  48  have a width Wt, Wb which is larger than a height Ht, Hb of the lateral walls  51 ,  52 . 
     The bottom walls  53 ,  54  are continuous to the lateral walls  51 ,  52  and formed parallel with associated ones of the upper and lower walls  44 ,  45 . The lateral walls  51 ,  52  are slanted in an angle range of 90 degrees plus/minus 15 degrees with respect to the upper and lower walls  44 ,  45 , and otherwise disposed orthogonally to or perpendicularly of the upper and lower walls  44 ,  45 . 
     The vehicle body side part structure is provided with a reinforcement member  64 ,  65 , which is disposed on at least one of a central joining portion  56  of the central part  22  where the center pillar  17  is joined and a front joining portion  57  of the front part  27  where the front pillar  16  is joined in such a manner that the reinforcement member  64 ,  65  closes the openings  61 ,  62  opposing the bottom walls  53 ,  54  to define closed cross sections jointly the upper and lower beads  47 ,  48 . 
     The reinforcement member  64  is located at the central joining portion  56 , while the reinforcement member  65  is located at the front joining portion  57 . 
     The outer side sill member  37  also includes a vertical wall  67  which is continuous to or connected between the upper and lower walls  44 ,  45  and located on the vehicle exterior side  41 . The vertical wall  67  has a lateral bead  68  formed as a recessed portion similar to the upper and lower beads  47 ,  48 . By thus providing the lateral bead  68 , the number of sides and angles of the polygonal shape of the closed cross section of the side sill  15  is increased. 
     The reinforcement member  64 ,  65  is configured to close the openings of the upper and lower beads  47 ,  48  and the opening of the lateral bead  68 , thus defining respective closed sections together with the beads  47 ,  48  and  68 . 
     As shown in  FIG. 2 , the reinforcement member  65  has a rearward extension or elongated portion  71  extending rearwardly of the vehicle  12  from the front joining portion  57  by a desired length Lfr. The reinforcement member  65  also has a forward extension or elongated portion  72  extending forwardly of the vehicle  12  from the front joining portion  57  by a desired length Lff. This forward elongated portion  72 , however, may be omitted. 
     Similarly, the reinforcement member  64  has at least one extension or elongated portion extending longitudinally forward or rearward of the vehicle  12  from the central joining portion  56 , as shown in  FIG. 2 . For instance, the reinforce member  64  has a forward extension  73  elongated by a desired length Lmf. The reinforcement member  64  also has a rearward extension  74  extending rearwardly of the vehicle  12  from the central joining portion  56  by a desired length Lmr. 
     The reinforcement member  64  has an upper reinforcing part  77  which closes the opening  61  of the upper bead  47 , thereby defining a closed cross section of the upper bead  47 . The upper reinforcing part  77  laps over the upper wall  44  and is joined by spot-welding to the upper  44  wall at welded parts  78 . 
     Similarly, the reinforcement member  64  also has a lower reinforcing part  81  which closes the opening  62  of the lower bead  48 , thereby defining a closed cross section of the lower bead  48 . The lower reinforcing part  81  is disposed continuous to the upper reinforcing part  77 , laps over the lower wall  45 , and is joined by spot-welding to the lower wall  45  at welded parts. 
     Furthermore, the reinforcement member  64  provides a vertical wall reinforcing part  84  which closes an opening  83  of the lateral bead  68 , thereby defining a closed cross section of the lateral bead  68 . The vertical wall reinforcing part  84  is disposed continuous to the upper and lower reinforcing parts  77 ,  81 , laps over the vertical wall  67 , and is joined by spot-welding to the vertical wall  67  at welded parts  85 . 
     The reinforcement member  65  is constructed in a similar manner with the reinforcement member  64 , and may be constructed in a modified form of the reinforcement member  64  according to various conditions required. For instance, the forward extension  72  may be omitted. 
     The upper bead  47  shown in  FIG. 5  is formed on the side sill  15  shown in  FIG. 2  so as to extend along the full length of the side sill  15  in the longitudinal direction of the vehicle body. The upper bead  47  has the pair of lateral walls  51 ,  51  projecting inwardly (in the direction of arrow a 4 ) of the side sill  15  and the bottom wall  53  formed integrally with the lateral walls  51 ,  51 . 
     Similarly, the lower bead  48  is formed to extend along the full length of the side sill  15  in the longitudinal direction of the vehicle body. The lower bead  48  has the pair of lateral walls  52 ,  52  projecting inwardly (in the direction of arrow a 4 ) of the side sill  15 , and the bottom wall  54  formed integrally with lateral walls  52 ,  52 . 
     Further, the lateral bead  68  extends substantially horizontally along the full length of the side sill  15  in the longitudinal direction of the vehicle body. The lateral bead  68  a pair of lateral walls  88 ,  88  protruding inwardly (in the direction of arrow a 4 ) of the side sill  15 , and the bottom wall  91  formed integrally with lateral walls  88 ,  88 . 
     The upper wall  44 , vertical wall  67  and lower wall  45  of the outer side sill member  37  are configured to be flat to facilitate the welding exerted thereon. The bottom walls  53 ,  54 ,  91  of the upper, lower and lateral beads  47 ,  48 ,  68  are also configured to be flat. The front pillar  16  and the center pillar  17  are jointed to the above-mentioned outer side sill member  37 . 
     The center pillar  17  is formed of an outer member  93  and an inner member  94 , as shown in  FIGS. 3 to 5 . The outer member  93  has a U-shaped cross section, and an open end of the outer member  93  is closed by the inner member  94 , so that the center pillar  17  has a closed cross section. Namely, the center pillar  17  has a hollow structure. The hollow space communicates with the opening of the upper bead  47  of the outer side sill member  37  of the side sill  15  when the reinforcement member  64  is not present. 
     The outer member  93  of the center pillar  17  is formed by a side wall  96 , a front wall  97  and a rear wall  98 . The center pillar side wall  96  has a first joint end  101  ( FIG. 3 ) disposed at a lower end portion thereof, and the first joint end  101  is joined to the vertical wall  67  of the outer side sill member  37  with the vertical wall reinforcing part  84  of the reinforcement member  64  interposed therebetween. 
     Additionally the center pillar rear wall  98  has a second joint end  102  ( FIG. 4 ) disposed at the lower end portion thereof, and the second joint end  102  is joined to the upper wall  44  of the outer side sill member  37  with the upper reinforcing part  77  of the reinforcement member  64  interposed therebetween. 
     Similarly the center pillar front wall  97  has a third joint end  103  ( FIG. 5 ) disposed at the lower end portion thereof, and the third joint end  103  is joined to the upper wall  44  of the outer side sill member  37  with the upper reinforcing part  77  of the reinforcement member  64  interposed therebetween. It should be noted that the third joint end  103  has a configuration similar with the second joint end  102 . 
     As described hereinabove, the center pillar  17  is joined to the side sill with the reinforcement member  64  interposed therebetween. The front pillar  16  is also joined to the side sill in the similar manner with the center pillar  17 . 
     The front pillar  16  is formed by an outer member  106  of a U-shaped cross section and an inner member  107 , and has a hollow structure of a closed section. The hollow space communicates with the opening of the upper bead  47  of the outer side sill member  37  of the side sill  15  when the reinforcement member  65  is not present. The outer member  106  is formed of a front pillar side wall  111 , a front pillar front wall  112  and a front pillar rear wall  113 . 
     The front pillar side wall  111  has a first joint end  116  disposed at a lower end portion thereof. Similarly, the front pillar rear wall  113  has a second joint end  117  at a lower end portion thereof, while the front pillar front wall  112  has a third joint end  118  at a lower end portion thereof. 
     The first, second and third joint ends  116 ,  117  and  118  of the front pillar are joined to the vertical wall reinforcing part  84  and the upper reinforcing part  77  of the reinforcement member  65 , respectively, which in turn join to the vertical wall  67  and the upper wall  44 , respectively of the outer side sill member  37  with the vertical wall reinforcing part  84  and the upper reinforcing part  77  disposed between the joint ends  116 ,  117 ,  118  and the vertical and upper walls  67 ,  44 . 
     Now operation of the vehicle body side part structure according to the first embodiment will be described with reference to  FIGS. 3 and 5 . 
     As shown in  FIG. 3 , when a load is applied to the side sill  15  in the direction of arrow F, for instance, the load is transmitted to the upper reinforcing part  77  of the reinforcement member  64  and disperses in a manner as indicated by arrow a 6 . As a result, the side sill  15  will be subject to a decreased amount of load, consequently increasing the strength of the side sill  15 . 
     Furthermore the load is transmitted to the upper reinforcing part  77  of the reinforcement member  64  positioned in an inside zone  121  of the center pillar  17  and then disperses in the manner as indicated by arrow a 6 , as the upper reinforcement part  77  serves to close the upper bead  47  to provide the closed cross section of the bead  47 . Consequently the upper bead  47  will be subject to a decreased amount of load, thereby further increasing the strength of the side sill  15 . 
     Sill further, the load is transmitted to the forward and rearward extensions  73 ,  74  of the reinforcement member  64  in a manner as indicated by arrows a 6 , a 7  and a 8 , and then disperses therealong. With this arrangement, an area provided to sustain a lateral collision load is increased in the longitudinal direction of the vehicle  12 . 
     Second Embodiment 
       FIGS. 6 to 9  illustrate a vehicle body side part structure according to a second embodiment of the present invention. Any members and elements of this embodiment which are similar to those of the first embodiment shown in  FIGS. 1 to 5  are denoted by the same reference numerals and will not be explained to avoid redundancy. 
     The vehicle body side part structure according to the second embodiment of the present invention includes a bulkhead  131  disposed inside the side sill  15  and partitioning a hollow internal space of the side sill  15 . The bulkhead  131  is located to overlap the reinforcement member  64  with the outer side sill member  37  interposed therebetween. 
     The reinforcement member  64  extends to such an extent that the reinforcement member  64  overlaps the bulkhead  131  in a widthwise direction of the vehicle while the bulkhead is positioned inside the side sill  15  to serve as a partition of the side sill  15 . 
     In  FIG. 9 , the bulkhead  131  and the outer side sill member  37  jointly defines a closed cross section. Specifically a combination of the bulkhead  131 , a wall part of the outer side sill member  37 , one lateral wall  51  of the upper bead  47  and one lateral wall  88  of the lateral bead  68  serves to define the closed cross section. 
     Similarly a combination of the bulkhead  131 , a wall part of the outer side sill member  37 , the other lateral wall  88  of the lateral bead  68  and one lateral wall  52  of the lower bead  48  serves to define a closed cross section. 
     As shown in  FIG. 7 , the bulkhead  131  has a U-shaped configuration and includes first and second partition walls  133 ,  134  extending perpendicularly to the longitudinal direction of the side sill  15  to partition the internal space of the side sill  15 , and a central wall  135  formed integrally with the first and second partition walls  133 ,  134 . Each of the first and second partition walls  133 ,  134  includes an upper attachment strip (upper flange)  136 , a lower attachment strip (lower flange)  137  and a lateral attachment strip (lateral flange)  138  that are formed by bending orthogonally an upper edge, a lower edge and a free end edge, respectively, of each partition wall  133 ,  144 . 
     As shown in  FIG. 9 , the bulkhead  131  is mounted fixedly to the side sill  15  such that the upper attachment strip  136  is secured to the upper bead  47 , the lower attachment strip  137  is secured to the lower bead  48  and the lateral attachment strip  138  is secured to the lateral bead  68 . 
     Now installation of the bulkhead  131  to the side sill  15  will be briefly explained hereinbelow. 
     Firstly the bulkhead  131  is placed to be directed toward the outer side sill member  37  as indicated by arrow b 1  shown in  FIGS. 7 and 8 . Then the bulkhead  131  is fitted in between the upper and lower beads  47 ,  48  as shown in  FIG. 9 . 
     Subsequently, the bulkhead  131  is fixed temporally in the side sill  15  by a suitable jig and welded thereto. The welding is achieved by a spot-welding process such that the upper and lower attachment strips  136 ,  137  are bonded at welded portions  141  to the corresponding bottom walls  53 ,  54  of the upper and lower beads  47 ,  48 , respectively, and the lateral attachment strip  138  is bonded at a welded portion  41  to the bottom wall  91  of the lateral bead  68 . Upon completion of those welding works, the outer side sill member  37  and the inner side sill member  38  are welded fixedly to each other. 
     Now an operation of the vehicle body side part structure according to the second embodiment will be described with reference to  FIGS. 6 and 9 . 
     When a load F 2  is applied to the side sill  15  of the vehicle body side part structure according to the second embodiment, the load is transmitted to the reinforcement member  64  and subsequently to one longitudinal end of the reinforcement member  64  where the bulkhead  131  is located. Thus, from the one longitudinal end of the reinforcement member  64 , the load F 2  is transmitted via the outer side sill member  37  to the bulkhead  131  and thus dispersed into the bulkhead  131 . As a result, the side sill  15  will be subject only to a decreased amount of load, thereby increasing the strength of the side sill  15 . 
     Third Embodiment 
     Now, a vehicle body front part structure according to a third embodiment of the present invention is explained with reference to  FIGS. 10 and 11 .  FIG. 10  corresponds to  FIG. 9 . Any structural features of this embodiment which are similar to those of the first and second embodiments shown in  FIGS. 1 to 9  are denoted by the same reference numerals and will not be explained to avoid redundancy. 
     As shown in  FIGS. 10 and 11 , the vehicle body side part structure according to the third embodiment includes a bulkhead  131 B which is provided with an engagement recess  151  fitted with the lateral bead  68 . The engagement recess  151  has a bottom  152  which is in contact with the bottom wall  91  of the lateral bead  68 . The bulkhead  131 B includes a lateral attachment strip  138 B having first and second attachment strip portions  154 ,  155  which are in contact with the vertical wall  67  of the outer side sill member  37 . 
     The recess fit portion  151  of the bulkhead  131 B is configured to fit with the lateral bead  68  formed on the outer side sill  37 . The bulkhead  131 B has first and second partition walls  133 B,  134 B, each provided with the lateral attachment flange  138 B in which the engagement recess  151  is formed. 
     Consequently, that party of the lateral attachment flange  138 , which excludes the engagement recess  151 , namely the first and second attachment strip portions  154 ,  155  are in contact with the vertical wall  67  of the outer side sill member  37 . 
     Now installation of the bulkhead  131 B employed in the third embodiment of the present invention will now be briefly explained. 
     Firstly the bulkhead  1321 B is inserted into the outer side sill member  37  in a manner similar to the second embodiment as shown in  FIG. 8 . Then the bulkhead  131 B is fitted in between the upper and lower beads  47 ,  48  as shown in  FIG. 10  such that the first and second attachment strip portions  154 ,  155  of the lateral attachment strip  138 B are brought into contact with the vertical wall  67  of the outer side sill  37 . 
     Then the bulkhead  131 B is secured to the side sill by welding as was exerted for the second embodiment such that the first and second attachment strip portions  154 ,  155  are welded to the vertical wall  67  at welded portions  141 . Thereafter the outer side sill member  37  is welded fixedly to the reinforcement member  64  and the inner side sill member  38 . 
     As explained hereinabove, the vehicle body side part structure according to the third embodiment achieves similar function and advantageous effects with the second embodiment of the present invention. 
     Additionally, in the vehicle body side part structure according to the third embodiment, the bulkhead  131 B is supported by the outer side sill member  37  as the first and second attachment strip portions  154 ,  155  butt against the vertical wall  67  of the outer side sill member  37  as indicate by arrows b 2 , b 2 , when the bulkhead  131 B is fitted with the outer side sill member  37 . With this arrangement, the bulkhead  131 B is limited to tilt with respect to a vertical direction of the vehicle  11  (in a direction of arrow b 3 ), thus facilitating the assembling of the bulkhead  131 B onto the outer side sill member  37 . 
     Fourth Embodiment 
     A vehicle body side part structure according to a fourth embodiment of the present invention will be described with reference to  FIGS. 12 and 13 . Any structural features of this embodiment which are similar to those of the first embodiment shown in  FIGS. 1 to 5  are denoted by the same reference numerals and will not be explained to avoid redundancy. 
     For the vehicle body side part structure of the fourth embodiment, a bulkhead  161  is located in the side sill  15  at such position to overlap the reinforcement member  64  with the outer side sill member  37  interposed therebetween. The bulkhead  161  serves as a partition inside the side sill  15 . 
     A closed cross section is defined jointly by bulkhead  161  and the outer side sill member  37 . Specifically the bulkhead  161  defines the cross section jointly with a wall portion of outer side sill member  37 , one of the lateral walls  51  of the upper bead  47  and one of the lateral walls  88  of the lateral bead  68 . 
     Similarly the bulkhead  161  defines another cross section jointly with a wall portion of outer side sill member  37 , one of the lateral walls  52  of the lower bead  48  and the other lateral wall  88  of the lateral bead  68 . 
     The bulkhead  161  has a partition wall  162  which is provided with an attachment rim or flange  163  projecting at a right angle or orthogonally from a peripheral edge of the partition wall  162 . 
     The bulkhead  161  is installed to the side sill in a similar manner with the second embodiment. Each of the beads  47 ,  48  and  68  has respective bottom walls  53 ,  54  and  91  which are spot-welded to the attachment rim  163  at welded portions  141 . 
     The vehicle body side part structure according to the fourth embodiment achieves the similar function and advantageous effects with the second embodiment of the present invention. 
     Fifth Embodiment 
     A vehicle body side part structure according to a fifth embodiment of the present invention will be described with reference to  FIG. 14 .  FIG. 14  corresponds to  FIG. 13 . Any structural features of this embodiment which are similar to those of the first and fourth embodiment shown in  FIGS. 1 to 5 ,  12  and  13  are denoted by the same reference numerals and will not be explained to avoid redundancy. 
     A bulkhead  161 B according to the fifth embodiment is provided with an engagement recess  171  for engagement with the lateral bead  68 . The engagement recess  171  has a bottom  172  which is in contact with the bottom wall  91  of the lateral bead  68 . A peripheral attachment rim or flange  175  of the bulkhead  161 B has first and second attachment portions  176 ,  177  which are in contact with the vertical wall  67  of the outer side sill member  37 . 
     The bulkhead  161 B has a partition wall  174  and the attachment rim  175  is provided on and along a peripheral edge of the partition wall  174  and projecting at a right angle from the peripheral edge. The engagement recess  171  has an attachment portion  175   a  disposed at the bottom  172  thereof. 
     With this arrangement, of that part of the attachment rim  175  which faces the vertical wall  67 , first and second attachment strip portions  154 ,  155  excluding the attachment  175   a  of the engagement recess  171  are in contact with the vertical wall  67  of the outer side sill member. 
     The bulkhead  161 B is installed to the side sill in a similar manner with the third embodiment. The first and second attachment portions  176 ,  177  are spot-welded to the vertical wall  67  at welded portions  141 . 
     The vehicle body side part structure according to the fifth embodiment achieves the similar function and advantageous effects with the third embodiment of the present invention. 
     The beads of the embodiments described above are recessed portions dented inwardly of the closed cross section. However, the bead may be configured to protrude outwardly of the closed cross section. In such case, the bulkhead should be provided with an engagement protrusion for engagement with the corresponding bead protruding outwardly from the closed cross section. 
     The reinforcement member  64  explained hereinabove is of one piece consisting of the upper and lower reinforcing parts  77 ,  81  and the vertical reinforcing part  84 . However, these parts may be separated in to three pieces. 
     INDUSTRIAL APPLICABILITY 
     The vehicle body side part structure according to the present invention can be suitably used in a vehicle with an increased strength against a lateral collision. 
     REFERENCE SIGNS LIST 
     
         
         
           
               12  vehicle 
               13  passenger compartment 
               15  side sill 
               16  front pillar 
               17  center pillar 
               22  roof 
               27  front part of side sill 
               33  central part of side sill 
               37  outer side sill member 
               38  inner side sill member 
               44  upper wall 
               45  lower wall 
               47  upper bead 
               48  lower bead 
               51  lateral wall of recessed portion 
               52  lateral wall of recessed portion 
               53 ,  54  bottom wall of recessed portion 
               56  central joining portion 
               557  front joining portion 
               61 ,  62  opening of bead 
               64 ,  65  reinforcement member 
               67  vertical wall of outer side sill member 
               68  lateral bead 
               71 ,  74  rearward extension of reinforcement member 
               73  forward extension of reinforcement member 
               88  lateral wall 
               91  bottom wall 
               131 ,  131 B bulkhead 
               138  lateral attachment strip 
               151  engagement recess 
               161  bulkhead 
             Hb, Ht height of lateral wall of recessed portion 
             Wb, Wt width of bottom wall of recessed portion