Abstract:
A front structure of a vehicle body includes left and right front side frames, a dashboard lower panel, and left and right floor frame. The dashboard lower panel has a rear surface with a cross member provided thereon, and a lower part inclined downwardly rearwardly of the vehicle body. Front end of each of the left and right floor frames extends forwardly upwardly along the lower part of the dashboard lower panel and is joined by an adapter to a rear end of a respective one of the left and right front side frames. The adapter is joined to the cross member with the dashboard lower panel sandwiched therebetween.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a front vehicle body structure having left and right front side frames provided on left and right sides of a front part of a vehicle body, and left and right floor frames extending rearward from rear ends of the left and right front side frames. 
     BACKGROUND OF THE INVENTION 
     Front part of a vehicle body is provided with left and right front side frames and left and right floor frames, which are some of vital structural elements of the vehicle body. When a so-called head-on collision occurs in which a collision force acts on the front surface of the vehicle, the collision force on the front is transferred from the left and right front side frames to the left and right floor frames and dispersed to the rear of the vehicle body. Techniques for improving the left and right front side frames are disclosed in Japanese Patent Application Laid-Open Publication No. 2006-290311 (JP-A 2006-290311) and Japanese Patent Application Laid-Open Publication No. 2009-234495 (JP-A 2009-234495). 
     In the vehicle body front disclosed in JP-A 2006-290311, the rear halves of the left and right front side frames curve so as to draw closer to each other as they extend rearward, increasing the strength of the curved rear halves. In the vehicle body front disclosed in JP-A-2009-234495, the sudden twisting of the left and right front side frames relative to the collision force from the front is minimized. 
     Recently, there has been a demand for a technique for efficiently dispersing a collision force from the front through the entire vehicle body. To accomplish this, the floor frames must be firmly joined to the front side frames. 
     It follows that there is a need for a technique whereby the floor frames can be firmly joined to the front side frames and a collision force acted on the front surface of the vehicle can be efficiently transferred from the front side frames rearwardly of the vehicle body. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a front vehicle body structure comprising: left and right front side frames provided on left and right sides of a front part of a vehicle body and extending longitudinally of the vehicle body; a dashboard lower panel, disposed behind the left and right front side frames, for partitioning the vehicle body into front and rear parts; and left and right floor frames disposed behind the dashboard lower panel and extending longitudinally of the vehicle body, wherein each of the left and right front side frames comprises a hollow member of substantially quadrangular cross section, a cross member is provided on a rear end surface of the dashboard lower panel in such a manner as to extend transversely of the vehicle body, the dashboard lower panel has a lower part inclined rearwardly downwardly of the vehicle body, each of the left and right floor frames has a front end which extends forwardly upwardly of the vehicle body along the lower part of the dashboard lower panel and is joined via a respective one of left and a right adapters to a rear end of a respective one of the left and right front side frames, each of the left and right adapters is formed into a substantially box-shaped configuration so as to be joined to an end of a respective one of the left and right front side frames, and each of the left and right adapters is joined to the cross member with the dashboard lower panel sandwiched therebetween. 
     The left and right adapters are thus formed into substantially box-shaped configurations so as to be joined to an end of a respective one of the substantially quadrangular cross-sectioned left and right front side frames. Therefore, the left and right adapters can be joined extremely firmly to the rear ends of the left and right front side frames. As a result, the front ends of the left and right floor frames can be joined firmly to the rear ends of the left and right front side frames by the left and right adapters. 
     Furthermore, the dashboard lower panel is increased in rigidity and strength by being reinforced by the cross member provided to the rear surface. Moreover, the top parts of the left and right adapters are joined to the cross member, holding the dashboard lower panel from the sides. Therefore, when the vehicle undergoes a head-on collision, the collision force from the front of the vehicle is transferred from the front side frames to the floor frames, and is also transferred from the front side frames to the cross member via the top parts of the adapters. In other words, the collision force is efficiently transferred and dispersed throughout substantially the entire cross member and dashboard lower panel. The cross member and the dashboard lower panel are capable of sufficiently bearing the collision force. As a result, the collision force can be efficiently transferred and dispersed from the front side frames to the rear part of the vehicle body. 
     Preferably, each of the left and right front side frames is comprised of a front-half portion and a rear-half portion continuing from a rear end of the front-half portion, the front-half portion being formed into a linear shape elongated longitudinally of the vehicle body, the rear-half portions being curved with vehicle-widthwise inside surfaces coming closer to each other toward a rear part thereof, while each of the left and right front side frames houses therein a stiffener extending linearly longitudinally of the vehicle body, the stiffener having a front end joined to the rear end of the front-half portion and to a vehicle-widthwise inside wall and a rear end joined to a vehicle-widthwise outside wall of the respective adapter. 
     In a preferred form, each of the adapters is joined at a vehicle-widthwise inside wall to the inside wall of the respective one of the front side frames. 
     It is desirable that each stiffener be formed into a substantially U-shaped cross section opening in a vehicle width direction and has a top flange positioned at a top end and a bottom flange positioned at a bottom end, the top flange extending in the vehicle width direction and being joined to a top wall of the respective front side frame, the bottom flange extending in the vehicle width direction and being joined to a bottom wall of the respective front side frame. 
     It is preferred that each of the left and right adapters is comprised of a body and a reinforcing part joined to the body, the body being formed by folding a single plate material and comprised of a substantially quadrangular bottom plate faced longitudinally of the vehicle body and three side plates positioned on three sides of the bottom plate, the reinforcing part having a side plate positioned on a remaining side of the bottom plate, the side plate of the reinforcing part constituting a top part of the respective adapter and being joined to the cross member in such a manner as to sandwich the dashboard lower panel. 
     It is desirable that the structure further comprise left and right sub frame mount stiffeners for attaching a sub frame to lower parts of the left and right front side frames and each of the left and right sub frame mount stiffeners be provided to a lower surface of a rear part of the respective front side frame and comprised of a mount for attaching the sub frame and a reinforcing part, provided to a front part of the mount, for reinforcing the respective side frame, a front end of the reinforcing part extending up to below the front end of the stiffener housed in the respective front side frame. 
     It is preferred that each front side frame have a lower flange hanging down from a vehicle-widthwise outer end thereof, the mount have a substantially crank-shaped cross-sectioned and be comprised of a bottom plate running along a bottom wall of the respective front side frame, an inside flange rising from a vehicle-widthwise inner end of the bottom plate and joined to the vehicle-widthwise inside wall of the respective front side frame, and an outside flange hanging down from a vehicle-widthwise outer end of the bottom plate and joined to the lower flange of the respective front side frame, and the reinforcing part have a substantially reverse L-shaped cross section and is comprised of a bottom plate joined to the bottom wall of the respective front side frame and an inside flange rising from a vehicle-widthwise inner end of the bottom plate and joined to the vehicle-widthwise inside wall of the respective front side frame. 
     In a preferred form, the sub frame mount stiffener is provided to lie on the respective adapter. 
     It is desirable that each front side frames be comprised of a frame inner member positioned on a vehicle-widthwise inner side thereof and a frame outer member positioned on a vehicle-widthwise outer side thereof, the frame inner member have a substantially U-shaped cross section opening in the vehicle-widthwise outer side, the vehicle-widthwise-outer side open end of the frame inner member being closed off by the frame outer member, the front side frame be provided with a holding bracket for holding a collar nut for mounting an engine to be disposed between the left and right front side frames, and the front end of the stiffener be provided behind the holding bracket. 
     It is desirable that each of the left and right frame inner members have on a vehicle-widthwise surface a first bead, each of the left and right frame outer members have on a vehicle-widthwise surface a second bead, each of the left and right stiffeners have on a vehicle-widthwise surface a third bead, and the first bead, the second bead, and the third bead be positioned on the rear-half portion of the respective front side frame, be oriented toward the front end of the respective floor frame, and be superposed over each other in the vehicle width direction. 
     In a desired form, each of the left and right stiffeners have strength greater than the respective front side frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating a front part of a vehicle body, according to the present invention; 
         FIG. 2  is a perspective view illustrating a dashboard lower panel, a right front side frame, and a right floor frame of  FIG. 1 , as seen from an engine space; 
         FIG. 3  is a perspective view illustrating the dashboard lower panel, the right front side frame, and the right floor frame of  FIG. 2 , as seen from a passenger compartment; 
         FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a perspective view of the right front side frame and the right floor frame of  FIG. 2 , as seen from the engine space; 
         FIG. 6  is a perspective view illustrating the configuration of  FIG. 2 , with a frame inner member removed from the right front side frame of  FIG. 2 , as seen from the passenger compartment; 
         FIG. 7  is a top plan view illustrating the right front side frame and the right floor frame of  FIG. 2 ; 
         FIGS. 8A and 8B  are views illustrating details of an adapter for joining together the right front side frame and the right floor frame of  FIG. 5 ; 
         FIG. 9  is an exploded view illustrating the right front side frame, the right floor frame, and the right adapter of  FIG. 7 ; 
         FIG. 10  is a cross-sectional view taken along line  10 - 10  of  FIG. 5 ; 
         FIG. 11  is a cross-sectional view taken along line  11 - 11  of  FIG. 5 ; 
         FIG. 12  is a cross-sectional view taken along line  12 - 12  of  FIG. 5 ; 
         FIG. 13  is a cross-sectional view taken along line  13 - 13  of  FIG. 5 ; 
         FIG. 14  is a perspective view showing a stiffener of  FIG. 6 ; 
         FIG. 15  is a perspective view illustrating the stiffener of  FIG. 14 , as seen from a transversely outer side of the vehicle body; 
         FIG. 16  is a side elevational view showing the configuration of  FIG. 5 , with the frame outer member removed from the right front side frame, as seen from the transversely outer side of the vehicle body; 
         FIG. 17  is a perspective view of the configuration of  FIG. 5 , with beads provided on the frame inner member of the right front side frame; 
         FIG. 18  is a side elevational view showing the configuration of  FIG. 17 , with the beads provided on the frame outer member of the right front side frame, as seen from the transversely outer side of the vehicle body; 
         FIG. 19  is a bottom view illustrating on an enlarged scale an primary part of the right front side frame of  FIG. 5 ; 
         FIG. 20  is a view illustrating the right front side frame and the right floor frame of  FIG. 17 , as seen from a transversely inner side of the vehicle body; 
         FIG. 21  is a cross-sectional view taken along line  21 - 21  of  FIG. 20 ; and 
         FIG. 22  is a cross-sectional view taken along line  22 - 22  of  FIG. 20 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1 through 3 , a vehicle  10  is a passenger vehicle, for example, and formed inside a vehicle body  13  are a front-part engine space  29  and a passenger compartment  28  positioned directly behind the engine space  29 . The vehicle body  13  is composed of a monocoque body and is formed symmetrically to the left and right about a vehicle width center line CL extending in the forward-backward direction of the vehicle through the widthwise center of the vehicle  10 . The front part of the vehicle body  13  includes left and right front side frames  16 ,  17 , a dashboard lower panel  19 , and left and right floor frames  24 ,  25 . 
     As shown in  FIGS. 1 through 4 , the dashboard lower panel  19  is a wall which is positioned behind the left and right front side frames  16 ,  17  and which partitions the vehicle body  13  into a front and a rear, or in other words which separates the front-part engine space  29  from the rear passenger compartment  28 . The dashboard lower panel  19  is composed of an upper-half-part vertical plate  19   a  and a lower-half-part inclined plate  19   b . The vertical plate  19   a  is formed into a substantially vertical plate shape. The inclined plate  19   b  is inclined downward and to the rear from the bottom end of the vertical plate  19   a.    
     Furthermore, the dashboard lower panel  19  has a joint cover  18  in an area where a steering shaft (not shown) is inserted, as shown in  FIGS. 2 and 3 . The joint cover  18  has an opening  18   a  for inserting the steering shaft, and the joint cover  18  is laid over and joined to the surface of the dashboard lower panel  19  that faces the engine space  29 . 
     Furthermore, the dashboard lower panel  19  is reinforced by a cross member  23  superposed on the surface  19   d  (the rear surface  19   d ) facing into the passenger compartment  28 , as shown in  FIGS. 3 and 4 . The cross member  23  is a long, thin member which is positioned in a corner  19   c  between the vertical plate  19   a  and the inclined plate  19   b  and which runs in the vehicle width direction, and this member has a substantial L shape in cross section as seen from the vehicle width direction. The cross member  23  has a top flange  23   a  extending upward from the top end, and a bottom flange  23   b  extending rearward and downward from the bottom end. The top flange  23   a  is superposed on and joined to the vertical plate  19   a  from the passenger compartment  28 . The bottom flange  23   b  is superposed on and joined to the inclined plate  19   b  from the passenger compartment  28 . 
     The cross member  23  configured in this manner is divided in two in the vehicle width direction at the portion positioned in the joint cover  18 , as shown in  FIGS. 2 and 3 . However, the cross member  23  is integrated left to right by the joint cover  18 , the dashboard lower panel  19 , and the cross member  23  being joined together. The cross member  23  can also be configured from a single component having the same configuration as the component divided in two as described above. 
     As shown in  FIGS. 1 through 3 , the left and right front side frames  16 ,  17  are positioned on the left and right sides of the front part of the vehicle body  13  (the portion farther forward than the dashboard lower panel  19 ), and the frames extend in the forward-backward direction of the vehicle body  13 . 
     The left and right floor frames  24 ,  25  are members which extend rearward from the rear ends  21 ,  21  (the frame rear ends  21 ,  21 ) of the left and right front side frames  16 ,  17  to be positioned in the passenger compartment  28 , and which support a floor panel  31  (see  FIG. 3 ). To be more specific, front ends  67  of the left and right floor frames  24 ,  25 , i.e. left and right floor frame front parts  67  are joined by left and right adapters  22  to the rear ends  21 ,  21  of the left and right front side frames  16 ,  17 . The left and right floor frame front parts  67  extend rearward and downward from the front ends along the lower surface of the inclined plate  19   b  of the dashboard lower panel  19 . 
     As shown in  FIGS. 3 ,  4 , and  7 , the right floor frame  25  is configured from a member having a substantially U-shaped cross section which opens at the top. The left floor frame  24  has the same configuration. To be more specific, the right floor frame  25  is a component formed by folding a steel plate or another plate member, and is composed of a substantially flat bottom plate  121  (a lower part  121 ), an inner plate  108  (an inner vertical part  108 ) standing upright from the inside end of the bottom plate  121  in the vehicle width direction, and an outer plate  112  (an outer vertical part  112 ) standing upright from the outer end of the bottom plate  121  in the vehicle width direction. 
     Furthermore, the left and right floor frames  24 ,  25  comprise left and right sub frame rear mounts  64  (see  FIG. 6 ) and left and right outriggers  66 ,  66 . The sub frame rear mounts  64  are members for mounting the rear end of a sub frame  34  (see  FIG. 1 ). The left and right outriggers  66 ,  66  extend from the left and right floor frames  24 ,  25  outward in the vehicle width direction to left and right side sills  36 ,  37 . 
     The left and right front side frames  16 ,  17 , the left and right adapters  22 , and the left and right floor frames  24 ,  25  are formed in left-to-right symmetry about the vehicle width center line CL. The right front side frame  17  is described in detail hereinbelow. The left front side frame  16  is not described because it has the same configuration as the right front side frame  17 . The same applies to the left and right adapters  22  and the left and right floor frames  24 ,  25 . 
     As shown in  FIGS. 7 and 10 , the right front side frame  17  is a so-called hollow member formed into a closed cross section having a substantially quadrangular shape (e.g. a rectangular cross section). In other words, the front side frame  17  has a closed cross-section structure which is rectangular in cross section, composed of a frame inner member  26  (body  26 ) positioned on the inner side in the vehicle width direction and a frame outer member  27  (lid member  27 ) positioned on the outer side in the vehicle width direction. 
     The frame inner member  26  is configured from a member substantially U-shaped in cross section whose outer side in the vehicle width direction is open as shown in  FIGS. 5 and 10 . To be more specific, the frame inner member  26  is a component formed by folding a steel plate or another plate member, and is composed of a substantially perpendicular vertical plate  43  (inside wall  43 , wall  43  on the vehicle-widthwise inner side) positioned toward the inside in the vehicle width direction, a top plate  71  (top wall  71 ) extending outward in the vehicle width direction from the top end of the vertical plate  43 , and a bottom plate  72  (bottom wall  72 ) extending outward in the vehicle width direction from the bottom end of the vertical plate  43 . 
     The top plate  71  has a flange  74  extending upward from the outer end in the vehicle width direction. The bottom plate  72  has a flange  75  extending downward from the outer end in the vehicle width direction. With these flanges  74 ,  75 , the overall cross-sectional shape of the frame inner member  26  is a substantially hat-shaped cross section. The frame outer member  27  is a vertical plate-shaped member positioned so as to face towards the frame inner member  26 . The top and bottom flanges  74 ,  75  are joined to the frame outer member  27 , whereby the frame inner member  26  is joined to the frame outer member  27 . 
     The overall general shape of the right front side frame  17  is as follows. When the vehicle body  13  is viewed from above as seen in  FIG. 7 , the front-half portion  38  (front frame part  38 ) of the front side frame  17  is formed to be substantially linear in the forward-backward direction of the vehicle. The rear-half portion  41  (rear frame part  41 ) of the front side frame  17  extends rearward from the rear end of the front-half portion  38  while curving toward the vehicle-widthwise center and to the rear of the vehicle. 
     Furthermore, when the vehicle body  13  is viewed from above as seen in  FIG. 7 , the outer surface in the vehicle width direction of the right front side frame  17  is formed into a substantial wave shape in the forward-backward direction of the vehicle. To be more specific, formed continuously from the front end to the rear end of the frame outer member  27  are, in order from the front, a first indented fold  81 , a distended fold  82 , and a second indented fold  83 . 
     The first indented fold  81  is an indented region which is recessed inward in the vehicle width direction, and is positioned slightly forward from the center positioned halfway along the full length of the front side frame  17 . The frame outer member  27  inclines toward the first indented fold  81  from the front end. 
     The distended fold  82  is a distended region which protrudes outward in the vehicle width direction from the first indented fold  81 , and is positioned near the border between the front-half portion  38  and the rear-half portion  41  of the front side frame  17 . The frame outer member  27  inclines toward the distended fold  82  from the first indented fold  81 . 
     The second indented fold  83  is an indented region which is recessed inward in the vehicle width direction, and is positioned near the rear end of the front side frame  17 . The frame outer member  27  inclines toward the second indented fold  83  from the distended fold  82 . 
     The end surface of the frame inner member  26  on the outer side in the vehicle width direction is formed into a substantial wave shape in the forward-backward direction of the vehicle to align with the frame outer member  27 . The size of the front side frame  17  in the vehicle width direction is designed so that the front end is the largest, the region of the first indented fold  81  is the smallest, and the region of the distended fold  82  is larger than the region of the first indented fold  81 . Therefore, the cross-sectional area of the front side frame  17  is largest in the front end, gradually decreasing from the front end to the first indented fold  81 ; and smallest in the region of the first indented fold  81 , gradually increasing from the first indented fold  81  to the distended fold  82 ; wherein the region of the distended fold  82  is greater than the region of the first indented fold  81 . 
     As shown in  FIGS. 5 through 7 , a stiffener  46  greater in strength than the front side frame  17  is provided inside the rear frame part  41  of the right front side frame  17 . Therefore, it is possible to improve the characteristic of transmitting collision force from the front which acts in the longitudinal direction of the front side frame  17 . For example, the material of the stiffener  46  is configured from a material having greater tensile strength (high-tensile steel or the like) than the front side frame  17 . For example, the practical cross-sectional area of the stiffener  46  which relates to tensile strength is designed to be greater than the practical cross-sectional area of the front side frame  17 . 
     As described above, the front frame part  38  of the front side frame  17  extends in a substantially linear manner in the forward-backward direction of the vehicle. The stiffener  46  is a long, thin member extending in the forward-backward direction so as to substantially coincide with the length of the vertical plate  43  (the inside wall  43 ) of the front frame part  38 , and the stiffener extends in a substantially linear manner in the forward-backward direction of the vehicle, as shown in  FIG. 7 . 
     As shown in  FIGS. 10 ,  14 , and  15 , the stiffener  46  is configured from a member having a substantially U-shaped cross section which opens outward in the vehicle width direction. To be more specific, the stiffener  46  is a component formed by folding a steel plate or another plate member, and is composed of a substantially perpendicular vertical plate-shaped stiffener body  101 , a top flange  102  extending outward in the vehicle width direction from the top end of the stiffener body  101 , and a bottom flange  103  extending outward in the vehicle width direction from the bottom end of the stiffener body  101 . 
     The stiffener body  101  is positioned so as to be held between the top plate  71  and the bottom plate  72  of the frame inner member  26 , and is extended in a substantially linear manner in the forward-backward direction of the vehicle so as to substantially coincide with the length of the vertical plate  43  of the front frame part  38  (see  FIG. 7 ). The top flange  102  is joined to the inside surface of the top plate  71  of the frame inner member  26 . The bottom flange  103  is joined to the inside surface of the bottom plate  72  of the frame inner member  26 . The top and bottom flanges  102 ,  103  are joined to the top plate  71  and the bottom plate  72 , thereby integrating the stiffener  46  with the frame inner member  26 . 
     As shown in  FIGS. 7 and 10 , a front end  46   a  of the stiffener  46 , i.e. the front end of the stiffener body  101  is positioned at the rear end  48  of the front frame part  38  and is joined to the inside surface of the vertical plate  43 . A rear end  46   b  of the stiffener  46  is joined to a rear end  53  of the frame outer member  27  as show in  FIGS. 5 through 7 ,  12 , and  13 . 
     Thus, the middle of the rear frame part  41  of the front side frame  17  which is formed into a closed cross section is partitioned in the vehicle width direction by the stiffener  46 . In other words, the front side frame  17  is formed into a rectangular closed cross section  126  as shown in  FIG. 2 , and another closed cross section  127  (see  FIGS. 2 and 21 ) is also formed by the frame outer member  27  and the stiffener  46 . 
     Beads are formed in the front side frame  17  and the stiffener  46  as shown in  FIGS. 14 through 18 . This is described in detail hereinbelow. 
     As shown in  FIGS. 14 through 16 , third beads  104 ,  105  are formed on the vehicle-widthwise surface of the stiffener body  101  of the stiffener  46 . As seen from the side of the vehicle body  13 , the third beads  104 ,  105  are positioned so as to overlap the vertical plate  43  of the frame inner member  26  and the frame outer member  27 , and these beads, which are long and thin in the forward-backward direction of the vehicle, are inclined so as to be oriented toward the front end  67  of the floor frame  25 . 
     As shown in  FIG. 17 , first beads  68 ,  69  are formed on the vertical plate  43  of the frame inner member  26 , on the vehicle-widthwise surface of the rear frame part  41  of the front side frame  17 . As seen from the side of the vehicle body  13 , the first beads  68 ,  69  are positioned so as to overlap the frame outer member  27  and the stiffener  46 , and these beads, which are long and thin in the forward-backward direction of the vehicle, are inclined so as to be oriented toward the front end  67  of the floor frame  25 . 
     As shown in  FIG. 18 , second beads  76 ,  77  are formed on the vehicle-widthwise surface of the frame outer member  27  of the front side frame  17 . As seen from the side of the vehicle body  13 , the second beads  76 ,  77  are positioned so as to overlap the vertical plate  43  of the frame inner member  26 , the frame outer member  27 , and the stiffener  46 , and these beads, which are long and thin in the forward-backward direction of the vehicle, are inclined so as to be oriented toward the front end  67  of the floor frame  25 . 
     Thus, the first beads  68 ,  69 , the second beads  76 ,  77 , and the third beads  104 ,  105  are positioned in the rear half portion  41  of the front side frame  17  and are provided to the front side frame  17  and the stiffener  46 . Moreover, the first beads  68 ,  69 , the second beads  76 ,  77 , and the third beads  104 ,  105  are all oriented towards the front end  67  of the floor frame  25  and are superposed over each other in the vehicle width direction. The rigidity and strength of the front side frame  17  are accordingly improved; therefore, when a collision load acts on the vehicle body  13  from the front of the vehicle, the collision load can be transferred smoothly from the front side frame  17  to the floor frame  25 . 
     Next, the right adapter  22  will be described in detail.  FIG. 8A  is an exploded view of the right front side frame  17 , the right floor frame  25 , and the right adapter  22  shown in  FIG. 5 .  FIG. 8B  is an enlarged view of the right adapter  22  (section  8 B) shown in  FIG. 8A . 
     As shown in  FIGS. 4 ,  8 A,  8 B,  12 , and  13 , the right adapter  22  is joined to the vertical plate  43 , the top plate  71 , and the bottom plate  72  of the frame inner member  26  and to the four sides of the frame outer member  27 , and is also joined via the dashboard lower panel  19  to the cross member  23 . The adapter  22  is a substantially quadrangular box-shaped member composed of a body  124  and a reinforcing part  125  joined to the body  124 . 
     The body  124  is fitted into and joined to the frame rear end  21  of the front side frame  17 . The front end  67  of the floor frame  25  (the floor frame front part  67 ) is fitted into and joined to the body  124 . 
     To be more specific, the body  124  is a component formed by folding a steel plate or the like, and is composed of a substantially quadrangular partitioning plate  106  (a bottom plate  106 ) which partitions the interior of the front side frame  17  lengthwise, and four side plates  55 ,  56 ,  118 ,  119  each extending toward the rear of the vehicle from the four sides of the partitioning plate  106 . The rear end of the body  124  is open. The four side plates  55 ,  56 ,  118 ,  119  are separated from each other. The rear ends of the four side plates  55 ,  56 ,  118 ,  119  are free ends. 
     In other words, the outer plate  55  (the outside part  55 , the wall  55  on the vehicle-widthwise outer side) is composed of a vertical plate extending toward the rear of the vehicle from the vehicle-widthwise outer side of the partitioning plate  106 . The inner plate  56  (the inside part  56 , the wall  56  on the vehicle-widthwise inner side) is composed of a vertical plate extending toward the rear of the vehicle from the vehicle-widthwise inner side of the partitioning plate  106 . The bottom plate  118  (the bottom wall  118 ) is composed of a horizontal plate extending toward the rear of the vehicle from the bottom side of the partitioning plate  106 . The top plate  119  (the top wall  119 ) is composed of a horizontal plate extending toward the rear of the vehicle from the top side of the partitioning plate  106 . The outer plate  55  extends higher upward than the top surface of the top plate  119 . 
     The reinforcing part  125  is a component formed by folding a steel plate or another plate member, and is superposed on and integrated with the top of the body  124 . The reinforcing part  125  is formed into a substantial crank shape as seen from the plate surface of the partitioning plate  106 , and is composed of a substantially horizontal ceiling plate  113  (a connecting ceiling part  113 ), a welding flange  116  standing upright from one end of the ceiling plate  113 , a welding flange  125   b  hanging down from the other end of the ceiling plate  113 , a reinforcing rib  125   a  extending inward in the vehicle width direction from the rear end of the welding flange  125   b , and a reinforcing rib  115  (a flange  115 ) standing upright from the rear end of the ceiling plate  113 . 
     The ceiling plate  113  is laid over and joined to the top surface of the top plate  119 . The welding flange  116  is laid over and joined to the inner surface of the outer plate  55 . The welding flange  125   b  is laid over and joined to the outer surface of the inner plate  56 . The reinforcing rib  125   a  continues into the reinforcing rib  115 . 
     As shown in  FIGS. 8A ,  8 B,  12 , and  13 , the surface on the vehicle-widthwise outer side of the outer plate  55  is laid over and joined to the rear end  46   b  of the stiffener body  101 , and is also laid over and joined to the inner surface of the frame outer member  27  of the front side frame  17 . The outer surface of the outer plate  55 , i.e. the surface on the vehicle-widthwise inner side is laid over and joined to the outer surface of the outer plate  112  of the floor frame  25 . The outer surface of the inner plate  56  is laid over and joined via the welding flange  125   b  to the inner surface of the vertical plate  43  of the front side frame  17 . In other words, the inner plate  56  is in effect joined to the vertical plate  43 . The inner surface of the inner plate  56  is laid over and joined to the outer surface of the inner plate  108  of the floor frame  25 . The outer surface of the bottom plate  118  is laid over and joined to the top surface of the bottom plate  72  of the front side frame  17 . The inner surface of the bottom plate  118  is laid over and joined to the lower surface of the bottom plate  121  of the floor frame  25 . 
     As shown in  FIGS. 4 ,  8 A,  8 B, and  12 , the reinforcing rib  115  and the reinforcing rib  125   a  are joined to the top flange  23   a  of the cross member  23 , holding the dashboard lower panel  19  from the sides. 
     The sub frame  34  is attached from below to the left and right front side frames  16 ,  17 , as shown in  FIG. 1 . An engine  32  and a transmission  33  are arranged transversely in the vehicle width direction and are mounted in the sub frame  34 . The left and right front side frames  16 ,  17  curve as shown in  FIG. 7  so that the engine  32  and the transmission  33  can be arranged transversely in the vehicle width direction. To be more specific, the right front side frame  17  comprises a front mount  58 , a first bracket  61 , a second bracket  62 , and a sub frame mount stiffener  63 , as shown in  FIG. 2 . The front mount  58  is a member for mounting the front end of the sub frame  34  shown in  FIG. 1 , and this mount hangs down from the front end of the front side frame  17 . The first and second brackets  61 ,  62  are members for mounting the engine  32  or the transmission  33  shown in  FIG. 1 . The sub frame mount stiffener  63  is a member for mounting the rear part of the sub frame  34 . 
     The first bracket  61  is provided inside and in the longitudinal substantial center of the front frame part  38  of the front side frame  17 , as shown in  FIGS. 6 and 7 . The first bracket  61  is composed of a first inner bonding part  87  for bonding to the inner surface of the vertical plate  43  of the frame inner member  26 , a first partitioning part  88  continuing from the first inner bonding part  87 , a collar nut  78  provided to the first partitioning part  88 , a first top bonding piece  91  extending upward from the top end of the first partitioning part  88 , and a first bottom bonding piece  92  extending downward from the bottom end of the first partitioning part  88 . 
     The first partitioning part  88  is formed into a substantial quadrangular shape which partitions the inside of the front side frame  17  lengthwise. The collar nut  78  is a member for attaching a mount (not shown). The first top bonding piece  91  is held and joined between the frame outer member  27  and the flange  74  shown in  FIG. 10 . The first bottom bonding piece  92  is held and joined between the frame outer member  27  and the flange  75  shown in  FIG. 10 . 
     The second bracket  62  is provided inside and in proximity to the rear end of the front frame part  38 , as shown in  FIGS. 6 and 7 . The second bracket  62  is composed of a second inner bonding part  95  for bonding to the inner surface of the vertical plate  43  of the frame inner member  26 , a second partitioning part  96  continuing from the second inner bonding part  95 , a collar nut  79  provided to the second partitioning part  96 , a second top bonding piece  97  extending upward from the top end of the second partitioning part  96 , and a second bottom bonding piece  98  extending downward from the bottom end of the second partitioning part  96 . 
     The second partitioning part  96  is formed into a substantial quadrangular shape which partitions the inside of the front side frame  17  lengthwise. The collar nut  79  is a member for attaching a mount (not shown). The second top bonding piece  97  is held and joined between the frame outer member  27  and the flange  74  shown in  FIG. 9 . The second bottom bonding piece  98  is held and joined between the frame outer member  27  and the flange  75  shown in  FIG. 10 . 
     As shown in  FIGS. 19 and 20 , the sub frame mount stiffener  63  is provided to the bottom of the rear frame part  41  of the front side frame  17  and is composed of a mount  59  and a reinforcing part  65 . Furthermore, the sub frame mount stiffener  63  is positioned so as to overlap the adapter  22 . 
     The mount  59  is a portion for attaching the sub frame  34  and is positioned in the rear part of the sub frame mount stiffener  63 , and the mount bulges downward from the lower surface of the rear frame part  41 . As shown in  FIGS. 20 and 22 , the mount  59  is formed into a substantially crank-form shape as seen from the front of the vehicle, and is composed of a bottom  59   c  substantially running along the bottom plate  72  of the frame inner member  26 , an outside flange  59   a  extending downward from the vehicle-widthwise outer end of the bottom  59   c , and an inside flange  59   b  extending upward from the vehicle-widthwise inner end of the bottom  59   c.    
     The reinforcing part  65  is a portion for reinforcing the front side frame  17 , and is positioned in the front part of the sub frame mount stiffener  63 . A front end  65   a  of the reinforcing part  65  extends below the front end  46   a  of the stiffener  46  from the mount  59 . As shown in  FIGS. 20 and 21 , the reinforcing part  65  is formed into a substantially L-form shape as seen from the front of the vehicle, and is composed of a bottom  65   c  substantially running along the bottom plate  72  of the frame inner member  26 , and an inside flange  65   b  extending upward from the vehicle-widthwise inner end of the bottom  65   c.    
     The following is a summary of the above description. As shown in  FIGS. 4 ,  8 A,  8 B, and  12 , the right adapter  22  is formed into a substantially box-form shape so as to be joined to the surfaces  27 ,  43 ,  71 ,  72  of the right front side frame  17  which has a substantially quadrangular cross section. Therefore, the adapter  22  can be joined extremely firmly to the rear end  21  of the front side frame  17 . As a result, the front end  67  of the right floor frame  25  can be firmly joined to the rear end  21  of the right front side frame  17  by the right adapter  22 . 
     Furthermore, the dashboard lower panel  19  is reinforced by the cross member  23  provided to the rear surface  19   d  as shown in  FIG. 4 , thereby improving rigidity and strength. Moreover, the top part of the right adapter  22  is joined to the cross member  23 , holding the dashboard lower panel  19  from the sides. Therefore, when the vehicle  10  undergoes a head-on collision, the collision force from the front of the vehicle  10  is transferred from the front side frame  17  to the floor frame  25 , and is transferred from the front side frame  17  to the cross member  23  via the top part of the adapter  22 . In other words, the collision force from the front is transferred and dispersed efficiently throughout substantially the entire cross member  23  and dashboard lower panel  19 . The cross member  23  and the dashboard lower panel  19  can sufficiently bear the collision force. As a result, the collision force can be efficiently transferred and dispersed to the rear part of the vehicle body  13  from the front side frame  17 . 
     Furthermore, the front side frame  17  is composed of the front-half portion  38  and the rear-half portion  41  which continues from the rear end of the front-half portion  38 , as shown in  FIG. 7 . The front-half portion  38  is formed into a long, thin, linear shape extending in the forward-backward direction of the vehicle body  13 . The rear-half portion  41  curves while its vehicle-widthwise inside surfaces draw closer to each other as it extends rearward from the front end. 
     A front side frame  17  of such description can be configured from two members: the frame inner member  26 , which has a substantially U-shaped cross section opening in the vehicle width direction, and the frame outer member  27 , as shown in  FIG. 10 . Therefore, the front side frame  17  can be manufactured straightforwardly and with high precision, and is readily assembled. Moreover, molding costs can be reduced because the shape of the metal mold for folding (pressing) the front side frame  17  from a plate member can be simplified. 
     Furthermore, the stiffener  46 , which is formed to be linear in the forward-backward direction of the vehicle body  13 , is housed within the front side frame  17  as shown in  FIGS. 6 and 7 . The front end  46   a  of the stiffener  46  is joined to the rear end of the front-half portion  38  and to the vehicle-widthwise inside wall (the vertical plate  43 ). The rear end  46   b  of the stiffener  46  is joined to the vehicle-widthwise outside wall  55  of the adapter  22 . Therefore, when the collision force from the front acts on the front side frame  17 , the collision force can be transferred linearly in the forward-backward direction from the front-half portion  38  to the adapter  22  via the stiffener  46 . As a result, the collision force from the front can be transferred efficiently from the front side frame  17  to the rear of the vehicle body  13 . 
     Furthermore, the wall  56  on the vehicle-widthwise inside wall of the adapter  22  is joined to the wall  43  on the vehicle-widthwise inside wall of the front side frame  17  as shown in  FIGS. 8A ,  8 B, and  12 . The vehicle-widthwise inside surface of the front side frame  17  has a shape which curves toward the vehicle-widthwise center as described above. The adapter  22  creates resistance against a bending moment created in the front side frame  17  in accordance with the collision force from the front, and the bending moment can be dispelled. 
     Furthermore, as shown in  FIGS. 2 ,  11 ,  20 , and  21 , the stiffener  46  is formed into a substantially U-shaped cross section opening in the vehicle width direction, and the stiffener has both the top flange  102  positioned at the top end and the bottom flange  103  positioned at the bottom end. The top flange  102 , which extends in the vehicle width direction, is joined to the top wall  71  of the front side frame  17 . The bottom flange  103 , which extends in the vehicle width direction, is joined to the bottom plate  72  of the front side frame  17 . Therefore, a closed cross section  126  having a substantially rectangular cross section is formed by the front side frame  17 . Furthermore, another closed cross section  127  is formed by the stiffener  46  and the front side frame  17 . As a result, folding of the front side frame  17  can be prevented by the two closed cross sections  126  and  127 . 
     Furthermore, the adapter  22  is composed of the body  124  and the reinforcing part  125  joined to the body  124 , as shown in  FIGS. 4 ,  8 A, and  8 B. The body  124  and the reinforcing part  125  are folded components made from steel plates or other plate members. The body  124  is composed of the substantially quadrangular bottom plate  106  which faces in the vehicle forward-backward direction, and the three side plates  55 ,  56 ,  118  positioned on three sides of the bottom plate  106 . The reinforcing part  125  has a side plate  113  (the ceiling plate  113 ) positioned on the remaining side of the bottom plate  106 . The ceiling plate  113  constitutes the top part of the adapter  22 . In other words, the flange  115  of the remaining side plate  113  is joined to the cross member  23 , holding the dashboard lower panel  19  from the sides. 
     Thus, the adapter  22  can be readily manufactured by pressing a plate member because the body  124  and the reinforcing part  125  are folded components composed of plate members. Moreover, the adapter  22  is configured from two members: the body  124  and the reinforcing part  125 . Therefore, by estimating the extent of the load transmitted by the adapter  22  and increasing the strength of either the body  124  or the reinforcing part  125 , it is possible to control the direction of load transmission and the extent of the transmitted load. 
     Furthermore, as shown in  FIGS. 1 and 20 , the lower part of the front side frame  17  comprises a sub frame mount stiffener  63  for attaching the sub frame  34 . The sub frame mount stiffener  63  is a member provided to the lower surface of the rear part of the front side frame  17 , and is composed of the mount  59  for attaching the sub frame  34 , and the reinforcing part  65  provided to the front part of the mount  59  for reinforcing the front side frame  17 . Thus, the front side frame  17  is reinforced by the sub frame mount stiffener  63 . Therefore, it is possible to increase the support strength required for the sub frame  34  to be supported by the front side frame  17 . 
     The front end of the reinforcing part  65  extends below the front end of the stiffener  46 , as shown in  FIG. 6 . Therefore, the strength of the stiffener  46  in the forward-backward direction of the vehicle can be increased by the reinforcing part  65 . As a result, it is possible to improve the transmission characteristics, whereby collision force from the front is transmitted rearward by the stiffener  46 . 
     Furthermore, the front side frame  17  has a lower flange  75  which hangs down from the vehicle-widthwise outer end, as shown in  FIG. 22 . The mount  59  is a member having a substantially crank-shaped cross section (including a substantially Z-shaped cross section), composed of the bottom plate  59   c  running along the bottom wall  72  of the front side frame  17 , the inside flange  59   b  which stands upright from the vehicle-widthwise inner end of the bottom plate  59   c  and which is joined to the vehicle-widthwise inside wall  43  of the front side frame  17 , and the outside flange  59   a  which hangs down from the vehicle-widthwise outer end of the left-to-right bottom plate  59   c  and which is joined to the lower flange  75  of the front side frame  17 . Thus, since the mount  59  is firmly joined to the front side frame  17 , the sub frame  34  is supported by the front side frame  17  with a large amount of support strength. 
     Moreover, as shown in  FIG. 21 , the reinforcing part  65  is a member having a substantially reverse L-shaped cross section, composed of the bottom plate  65   c  joined to the bottom wall  72  of the front side frame  17 , and the inside flange  65   b  which stands upright from the vehicle-widthwise inner end of the bottom plate  65   c  and which is joined to the vehicle-widthwise inside wall  43  of the front side frame  17 . The periphery of the front side frame  17 , which supports the sub frame  34 , is also reinforced by the reinforcing part  65 . 
     Therefore, the support strength whereby the front side frame  17  supports the sub frame  34  can be increased, and the front side frame  17  can be reinforced. 
     Furthermore, the sub frame mount stiffener  63  is provided so as to overlap the adapter  22 , as shown in  FIGS. 4 and 5 . In other words, the front side frame  17 , the adapter  22 , and the rear end of the sub frame mount stiffener  63  are overlapped and joined together. Therefore, the support strength whereby the front side frame  17  supports the sub frame  34  can be further increased, and the front side frame  17  can be reinforced. 
     Furthermore, the front side frame  17  is provided with a holding bracket  62  for holding the collar nut  79 , as shown in  FIGS. 6 and 7 . The collar nut  79  is a member for mounting the engine  32  (see  FIG. 1 ), which is arranged to the inside of the front side frame  17 . The front end  46   a  of the stiffener  46  is positioned behind the holding bracket  62  and is provided to the front side frame  17 . Therefore, the front side frame  17  can efficiently transfer collision force from the front to the rear part, without the region of the stiffener  46  being affected by the highly rigid engine. 
     The vehicle body  13  of the present invention is applicable in an automobile comprising an adapter  22  for bonding together the left and right front side frames  16 ,  17  and the left and right floor frames  24 ,  25 . 
     Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.