Abstract:
Disclosed is a vehicle body panel joining structure including a structural frame ( 30   b ) having a ridgeline in the lengthwise direction, which has one section joined to a first vehicle body panel ( 44 ) and another section joined to a second vehicle body panel ( 43 ); an overlap part ( 61 ) in which the first and second vehicle body panels are overlapped and which is arranged in such a way that the structural frame straddles the overlap part; a depressed part ( 64 ) which is disposed at a position avoiding the ridgeline on the structural frame and is abutted by the overlap part; and a spot welding part ( 65 ) which is joined to the depressed part ( 64 ), the first vehicle body panel, and the second vehicle body panel at the overlap part by means of spot welding.

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle body panel joining structure. 
     Priority is claimed on Japanese Patent Application No. 2009-285133, filed Dec. 16, 2009, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     A vehicle body structure is known in which the vehicle body has a coupling member that couples the rear end of a front side frame arranged at both sides of an engine compartment along the longitudinal direction, the front end of a side sill arranged at both sides of a vehicle compartment along the longitudinal direction, and the front end of a center frame arranged at the center of the vehicle compartment in the width direction of the vehicle along the longitudinal direction. 
     The coupling member includes an outrigger extending obliquely to behind toward the outside in the width direction of the vehicle and connected to the front end of the side sill, and a center frame extension extending obliquely to behind toward the inside in the width direction of the vehicle and connected to the front end of the center frame, so that during a collision of the vehicle, the collision load backward input to the front side frame is dispersed to the side sill and the center frame in the width direction of the vehicle via the coupling member and the deformation of the vehicle compartment can be suppressed to a minimum due to the collision load (see Patent Document 1). 
     Citation List 
     Patent Document 
     [Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2009-18725 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in a vehicle body production form where floor components including a floor panel are located on a vehicle body front component including a coupling member and spot welding is performed thereon, since the joining portion of a floor panel and a lower dashboard partitioning a vehicle compartment and an inside of an engine compartment is positioned inside (rear side) of the coupling member, which thus causes an obstruction when spot welding, a hole is required to be provided at the coupling member to insert the welding gun thereinto. 
     Thus, there are problems in that disposition of a cover is required to block the hole, the number of parts increases, and a precision jig is required to arrange a member to align the exact position of the hole. In addition, there is a problem in that transmission of the impact load decreases at the portion where the hole is provided. 
     An object of an embodiment of the invention is to provide a vehicle body panel joining structure in which a jig can be simplified without an increase in the number of parts and the rigidity of the vehicle body can also be increased without causing a problem in the transmission of an impact load. 
     Solution to Problem 
     In an embodiment of the invention, a vehicle body panel joining structure that joins a first vehicle body panel and a second vehicle body panel, the vehicle body panel joining structure includes a structural frame having a ridgeline in the lengthwise direction, which has one section joined to the first vehicle body panel and another section joined to the second vehicle body panel; an overlap part in which the first and second vehicle body panels are overlapped and which is arranged in such a way that the structural frame straddles the overlap part; a depressed part which is disposed at a position avoiding the ridgeline on the structural frame and is abutted by the overlap part; and a spot welding part which is joined to the depressed part, the first vehicle body panel, and the second vehicle body panel at the overlap part by means of spot welding. 
     In the embodiment described above, a configuration may be employed wherein a contact width between a bottom wall of the structural frame and the overlap part is gradually narrowed along the transmission direction of an impact load and the depressed part is formed in a water drop shape in plan view. 
     In the embodiment described above, a configuration may further include a coupling member that couples the rear end of a front side frame arranged at both sides of an engine compartment along the longitudinal direction thereof, the front end of a side sill arranged at both sides of a vehicle compartment along the longitudinal direction, and the front end of a center frame arranged at the center of the vehicle compartment in the width direction of the vehicle along the longitudinal direction, wherein the coupling member includes an outrigger extending obliquely to behind toward the outside in the width direction of the vehicle and connected to the front end of the side sill, and a center frame extension extending obliquely to behind toward the inside in the width direction of the vehicle and connected to the front end of the center frame, wherein a floor panel is placed across the side sill and the center frame, wherein a rear edge of a lower dashboard dividing the engine compartment and the vehicle compartment is joined to the front edge of the floor panel with the overlap part, wherein the structural frame is the outrigger, wherein the first vehicle body panel is the lower dashboard, and wherein the second vehicle body panel is the floor panel. 
     Advantageous Effects of Invention 
     According to the embodiment of the invention, since the structural frame is not required to be provided with a hole to insert a spot welding gun thereinto, a cover or the like is not required to block the hole and the number of parts does not increase. In addition, since the depressed part and the overlap part may be simply matched, a positioning jig can be simplified. Furthermore, the depressed part does not divide the ridgeline of the structural frame, so that the rigidity of the vehicle body can be increased without a problem in the transmission of an impact load. 
     In addition, in a further configuration, reduction of the cross-sectional area of the structural frame is minimized and a decrease in the strength of the vehicle body can be suppressed. 
     In addition, in a further configuration, since the outrigger is not required to be provided with a hole to insert a spot welding gun thereinto, a cover or the like is not required to block the hole and the number of parts does not increase. In addition, since the depressed part and the overlap part may be simply matched, a positioning jig can be simplified. Furthermore, the depressed part does not divide the ridgeline of the outrigger so that the rigidity of the vehicle body can be increased without a problem in the transmission of an impact load. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view illustrating a vehicle body of an automobile of an embodiment according to the invention. 
         FIG. 2  is a view seen from an arrow A in  FIG. 1   
         FIG. 3  is a bottom view of a front sub-frame. 
         FIG. 4  is a perspective view of a main portion below a floor seen from below a vehicle compartment. 
         FIG. 5  is a perspective view near the coupling member seen from the rear side. 
         FIG. 6  is a cross-sectional view taken along a line B-B of  FIG. 1 . 
         FIG. 7  is a bottom view illustrating a situation in which a rear outrigger is removed. 
         FIG. 8  is a perspective view of a rear outrigger seen from the rear side. 
         FIG. 9  is a cross-sectional view taken along a line C-C of  FIG. 7 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, embodiments of the invention will be described based on the drawings. 
       FIG. 1  is a view of a vehicle body of an automobile seen from a lower surface, and  FIG. 2  is a view seen from arrow A in  FIG. 1 . The outer shape of the vehicle body is illustrated in dashed lines in  FIGS. 1 and 2 . As shown in  FIGS. 1 and 2 , a vehicle body frame of the automobile includes a pair of left and right front side frames  12  and  12  that have closed cross-sectional structures and extend in the longitudinal direction of the vehicle body along both left and right sides of an engine room  11 , a pair of left and right side sills  14  and  14  that have closed cross-sectional structures and extend in the longitudinal direction of the vehicle body along both left and right sides of a vehicle compartment  13 , a pair of left and right rear side frames  17  and  17  that have closed cross-sectional structures and extend in the longitudinal direction of the vehicle body along both left and right sides of a fuel tank housing part  15  and a trunk  16 , and a pair of left and right upper members  19  and  19  that have closed cross-sectional structures, extend from the front end of the front side frames  12  and  12  upward to the rear and are coupled to the upper end of a pair of left and right front pillar lowers  18  and  18  rising from the front end of the left and right side sills  14  and  14 . 
     In addition, the vehicle body frame includes a front bumper beam  21  that extends in the width direction of the vehicle body and has both ends connected to the front ends of the front side frames  12  and  12  via front side frame extensions  20  and  20 , a dash lower cross member  22  that extends in the width direction of the vehicle body, provides a connection between the rear ends of the left and right front side frames  12  and  12 , and forms a closed cross-sectional structure with a lower dashboard  44  (described below), a front cross member  23  that extends in the width direction of the vehicle body, forms a closed cross-sectional structure on a front floor panel  43  (described below), provides a connection between middle parts, in the longitudinal direction of the vehicle body of the left and right side sills  14  and  14 , a middle cross member  24  that extends in the width direction of the vehicle body, provides a connection between the front ends of the left and right rear side frames  17  and  17 , and forms a closed cross-sectional structure with a rear floor panel  45  (described below), a rear cross member  25  that extends in the width direction of the vehicle body, provides a connection between middle parts, in the longitudinal direction of the vehicle body of the left and right rear side frames  17  and  17 , and forms a closed cross-sectional structure with the rear floor panel  45  (described below), a rear bumper beam  26  that extends in the width direction of the vehicle body and provides a connection between the rear ends of the left and right rear side frames  17  and  17 , a rear end frame  27  that extends in the width direction and connects the left and right rear side frames  17  and  17  between the rear cross member  25  and the rear bumper beam  26 , and a pair of left and right center frames  29  and  29  that extend along both the left and right sides of a floor tunnel  28  extending from the dash lower cross member  22  to the middle cross member  24 , and form a closed cross-sectional structure with the front floor panel  43  (described below). 
     Furthermore, the vehicle body frame includes a pair of left and right coupling members  30  and  30  that couple the front side frames  12  and  12 , the side sills  14  and  14 , and the center frames  29  and  29 , and a front sub-frame  31  that has a frame shape and is supported on a lower part of the left and right front side frames  12  and  12 . 
     Next, the coupling member  30  will be described. Here, since the left and right coupling members  30  and  30  have a mirror symmetric shape, one thereof will be explained. 
     As shown in  FIGS. 1 and 2 , the coupling member  30  is a member which is formed in a press with a steel plate and the cross-section thereof is opened to the upper side, and includes an outrigger  30   b , which joins to a rear end of the front side frame  12  and extends obliquely to the rear outside so as to be joined to a front end of the side sill  14 . The outrigger  30   b  is configured such that a front outrigger  30   fb  and a rear outrigger  30   bb , which have cross-sections opened to the upper side, are divided and joined together. A front sub-frame attaching stiffener  30   a  which projects downward in a cup shape is joined to a lower surface of the front outrigger  30   fb.    
     In addition, the coupling member  30  includes a center frame extension  30   c  which is joined to a side wall inside the front outrigger  30   fb  and extends obliquely to inward in the width direction of the vehicle body and to backward, and then is joined to the front end of the center frame  29 . The center frame extension  30   c  also has a cross-section opened to the upper side. 
     The outrigger  30   b  and the center frame extension  30   c  straddle the joint portion of the front floor panel  43  and the lower dashboard  44  so that a closed cross-sectional structure portion is formed at a lower side of the front floor panel  43  and the lower dashboard  44 . 
     A rubber bush joint  36  is accommodated inside the front sub-frame attaching stiffener  30   a  and a rear part of the front sub-frame  31  is fastened and fixed by a bolt  37  passing through the rubber bush joint  36 . Accordingly, the front sub-frame attaching stiffener  30   a  is set as a support point that elastically supports the rear part of the front sub-frame  31  arranged under the engine compartment  11  (see  FIG. 2 ). 
       FIG. 3  is a bottom view of the front sub-frame. As shown in  FIG. 3 , the front sub-frame  31  is configured such that a pair of left and right longitudinal frames  32  and  32 , which are mainly hydroform molding products, are connected in a square frame shape to a front cross member  33  made of a round pipe material and a rear cross member  34  made of a press molding product. The front cross member  33  is arranged at a position higher than the longitudinal frames  32  and  32 . A suspension part  38  shown in a dashed line is assembled at the front sub-frame  31 . 
     Here, at the connecting part between the longitudinal frames  32  and  32  and the front cross member  33 , a stiffening member  39  is disposed to wrap around a part of an end of the front cross member  33 , a front end of the longitudinal frames  32 , and an outside portion from the front end of the longitudinal frames  32  from the up and down direction to near the center thereof in the front and rear direction of the vehicle body. The stiffening member  39  is configured of an upper plate  40  and a lower plate  41 , which is formed in a press. 
     A collar  47  is disposed inside and at the outer front of the stiffening member  39  and a bolt  48  is inserted into the collar  47  thereof. The stiffening member  39  is fastened and fixed at the front end of the front side frame  12  via rubber bush joints  35  and  35  inside the front sub-frame attaching bracket  42  mounted at a front-end lower portion of the front side frame  12 . Accordingly, the lower surfaces of the front sub-frame attaching brackets  42  and  42  mounted at front-end lower surfaces of the front side frames  12  and  12  are configured as support points that elastically support the front end of the front sub-frame  31 . 
     The front floor panel  43  is arranged at the vehicle compartment  13  between both edges of the floor tunnel  28  and the side sills  14  and  14 . The center frame  29  is formed at both edges of the floor tunnel  28 , in which an upper portion of the center frame  29  is opened to rise to the upper side after being dropped in the lower side from the surface of the front floor panel  43 . The upper opening of the center frame  29  is closed and then the inside edge of each front floor panel  43  is joined to each side wall of the floor tunnel  28 . In addition, the outside edge of each front floor panel  43  is joined to an inside wall of the side sill  14 . 
     The front edge of the front floor panel  43  is joined to the lower and rear edge of the lower dashboard  44  from the upper side thereof. The rear edge of the front floor panel  43  is connected to the rear floor panel  45 , which configures a floor surface of a fuel tank housing part  15 , and a trunk  16  from the middle cross member  24 . In addition, a bulkhead  46  is joined to a position that is along the front cross member  23  inside the floor tunnel  28  in the width direction of the vehicle body. 
       FIG. 4  is a perspective view of a main portion below the floor seen from below the vehicle compartment,  FIG. 5  is a perspective view of near the coupling member seen from the rear side,  FIG. 6  is a cross-sectional view taken along a line B-B of  FIG. 1 ,  FIG. 7  is a bottom view illustrating a situation in which a rear outrigger is removed,  FIG. 8  is a perspective view of the rear outrigger seen from the rear side, and  FIG. 9  is a cross-sectional view taken along a line C-C of  FIG. 7 . 
     As shown in  FIGS. 4 and 5 , at both sides of the lower surface (illustrating only the left side in  FIG. 4 ) of the front of the front floor panel  43 , specifically, at a root portion of the outrigger  30   b  and the center frame extension  30   c  of the coupling member  30  which are positioned behind the front sub-frame attaching stiffener  30   a , a stiffener  50  is extended behind the vehicle body so as to cover the root portion, in which the stiffener  50  is joined to the outrigger  30   b , the center frame extension  30   c , the lower dashboard  44 , and the front floor panel  43 . The stiffener  50  is a member having a U-shaped cross-section opened upward and joins a flange part  53  disposed at the circumferential edge thereof so that a closed cross-sectional structure is formed under the lower dashboard  44  and the front floor panel  43 . 
     The stiffener  50  extends behind over the arrangement position of the front cross member  23 , and a bead  51  having a U-shaped cross-section and including a cross-sectional shape fitted in the cross-sectional shape of the stiffener  50  is recessed at the rear portion of the front floor panel  43 . The bead  51  is connected to the stiffener  50  and a rear end of the bead  51  is coupled to the middle cross member  24  arranged at behind the front cross member  23 . 
     Here, the stiffener  50  is configured of a front stiffener  54  having high strength and a rear stiffener  55  having low strength. A rear end position of the front stiffener  54  is aligned with a rear end position of the outrigger  30   b , in other words, the rear outrigger  30   bb  and a rear end of the rear stiffener  55  is continued to the bead  51 . 
     An inclined part  52  which is connected to the rear end of the stiffener  50  and inclines from in front of to behind the stiffener  50  is formed at the front end of the bead  51 . Specifically, as shown in  FIG. 2 , the inclined part  52  of the bead  51  is portioned where a front portion of a bottom wall  58  is inclined and a rear edge  59  of the stiffener  50  (rear stiffener  55 ) is joined to the bottom wall  58 , and a side wall  56  of the bead  51  corresponding to the inclined part  52  is joined to a side wall  57  of the stiffener  50  (rear stiffener  55 ). 
     As shown in  FIGS. 6 and 7 , the front edge of the front floor panel  43  is overlapped at the rear edge of the lower dashboard  44  from the upper side thereof and then an overlap part  61  is formed. The spot welding is performed at two places of the overlap part  61 . In the assembly process of the vehicle body, the overlap part  61  is an overlap part that is set as a joining margin when assembling a floor component including the front floor panel  43  and a vehicle body front component including the lower dashboard  44  consisting of the coupling member  30 . 
     Here, the floor component represents an assembly of the panel component parts modulated including the front floor panel  43 . The vehicle body front component means an assembly of the panel component parts modulated including the lower dashboard of the engine compartment  11 . 
     In addition, in  FIG. 7 , two hit points  60  and other hit points  60  and  60  of the spot welding of the rear outrigger  30   bb  are illustrated in hatching. 
     At a bottom wall  62  of the rear outrigger  30   bb  of the coupling member  30 , in other words, at a position (see  FIG. 5 ) to avoid ridgelines  63  and  63  (in particular, the ridgeline of the rear side) of the rear outrigger  30   bb  in the lengthwise direction and at a position corresponding to directly under the overlap part  61  where the lower dashboard  44  and the front floor panel  43  are overlapped, as shown in  FIG. 6 , a depressed part  64 , which contacts the overlap part  61  at the rear surface from the lower side thereof is recessed upwardly. 
     Specifically, the depressed part  64  is a spot welding part  65  that is provided for performing the spot welding of the rear outrigger  30   bb  at the same time when performing spot welding of the overlap part  61  where the lower dashboard  44  and the front floor panel  43  are overlapped. The depressed part  64  is formed in a water drop shape in plan view so that a contact width between the overlap part  61  and the bottom wall  62  of the rear outrigger  30   bb  is gradually narrowed along the transmission direction (shown in arrows in  FIG. 5 ) of the impact load. Otherwise, the depressed part  64  in plan shape is an egg shape, an oval shape having one symmetry axis, or a teardrop shape. Otherwise, the depressed part  64  in plan shape has a smooth curved shape having substantially one symmetry axis and two non-symmetry axes (or, closed curve). 
     Here, as shown in  FIG. 5 , similar to the rear outrigger  30   bb , since the center frame extension  30   c  and the front stiffener  54  straddle the overlap part  61 , holes  72  and  73  are formed at positions corresponding to the spot welding part  65  of the overlap part  61  respectively, and the spot welding gun can be inserted into the holes  72  and  73 . 
     As shown in  FIG. 8 , the rear outrigger  30   bb  includes two side walls  66  and  68  rising from the bottom wall  62 , and a flange part  67  of one side wall  66  is joined to a rear surface of the front floor panel  43  and a flange part  69  of the other side wall  68  is joined to a rear surface of the lower dashboard  44 , a front edge  70  of the bottom wall  62  is joined to the front outrigger  30   fb , and a flange part  71  of a rear edge of the bottom wall  62  is joined to the side sill  14 . As shown in  FIG. 9 , the depressed part  64  of the rear outrigger  30   bb  formed at the bottom wall  62  is the spot welding part  65  including two hit points  60  and  60 , and two hit points  60  and  60  are arranged side-by-side in the width direction of the vehicle. 
     According to the embodiment described above, the front edge of the floor component including the front floor panel  43  is placed on the rear edge of the vehicle body front component provided with the lower dashboard  44  including the coupling member  30 , and then the overlap part  61  is formed. In a case where the overlap part  61  is subject to the spot welding, since the depressed part  64  of the bottom wall  62  of the rear outrigger  30   bb  of the coupling member  30  contacts the spot welding parts  65  and  65  of the lower dashboard  44  and the front floor panel  43  in a state where the floor component and the vehicle body front component are arranged at the assembling position, the spot welding gun is pressed against the depressed part  64  and the spot welding can be performed in two places at the front floor panel  43 , the lower dashboard  44  and the rear outrigger  30   bb.    
     Accordingly, as shown in a dashed line in  FIG. 9 , it is not required to provide two holes at the bottom wall  62  of the rear outrigger  30   bb  to insert the spot welding gun as in the related art, so that covers or the like are not required to block the holes after assembly and thus an increase of the number of parts can be suppressed. 
     In addition, since the depressed part  64  is formed by having a certain width, a bottom part of the depressed part  64  of the rear outrigger  30   bb  may be simply matched with the vicinity of the overlap part  61  where the rear edge of the lower dashboard  44  and the front edge of the front floor panel  43  are overlapped, so that it is possible to simplify the jig compared to the related art where the insert hole of the spot welding gun is required to be exactly positioned with the spot welding parts  65  and  65  of the overlap part  61 . 
     Thus, the depressed part  64  is formed at the position where the ridgeline  63  of the rear outrigger  30   bb  is not divided, so that there is no problem in the transmission of the impact load and the rigidity of the vehicle body can also be improved. 
     In other words, during collision of the front of the vehicle, the input load acting on the front part of the vehicle body is transmitted by the coupling member  30  to the side sills  14  and  14  of both sides in the width direction of the vehicle body and the center frames  29  and  29  of the center part in the width direction of the vehicle body, so as to disperse in the width direction of the vehicle body (illustrating in the arrows in  FIG. 5 ). When the load is transmitted to the rear outrigger  30   bb , since the depressed part  64  does not divide the ridgelines  63  and  63  between the bottom wall  62  and the side walls  66  and  68  of the rear outrigger  30   bb , the impact load can be reliably transmitted to the side sill  14 . 
     Thus, since the contact width between the overlap part  61  and the bottom wall  62  of the rear outrigger  30   bb  is formed to be gradually narrowed along transmission directions of the impact load, and the depressed part  64  is formed in the water drop shape in plan view, the reduction of the cross-sectional area of the rear outrigger  30   bb  is minimized and the decrease in the strength of the vehicle body can be suppressed. 
     In addition, the invention is not limited to the embodiment described above and for example, since the center frame extension  30   c  and the front stiffener  54  also straddle the overlap part  61 , as shown in  FIG. 5 , the holes  72  and  73  are formed at the positions corresponding to the overlap part  61  respectively, however the holes  72  and  73  may be configured as the depressed part similar to the depressed part  64  and may contact the overlap part  61 . According to the configuration described above, even in the arrangement positions of the center frame extension  30   c  and the front stiffener  54 , it is possible to simplify the jig similar to the arrangement positions of the outrigger  30   b , and the rigidity of the vehicle body can be improved without a problem in the transmission of the load. 
     REFERENCE SIGNS LIST 
       63  ridgeline 
       30   b  outrigger (structural frame) 
       44  lower dashboard (vehicle body panel) 
       43  front floor panel (vehicle body panel, floor panel) 
       61  overlap part 
       64  depressed part 
       65  spot welding part 
       62  bottom wall 
       11  engine compartment 
       12  front side frame 
       14  side sill 
       29  center frame 
       30  coupling member 
       30   c  center frame extension 
       13  vehicle compartment