JP4802589B2 - Lower body structure of automobile - Google Patents

Description

  The present invention relates to a lower body structure of an automobile, and more particularly, to a lower body structure of an automobile provided with a center frame extending in the longitudinal direction of the vehicle body between a pair of left and right side frames extending in the longitudinal direction of the vehicle.

  This type of vehicle body lower structure is normally disposed from the front side frame extending in the vehicle front-rear direction, the side frame formed by connecting the body side frame and the rear side frame in the front-rear direction, and exclusively from the body side frame to the rear side frame. A floor panel that forms a floor surface of the passenger compartment, and a center portion in the vehicle width direction bulges upward to form a floor tunnel portion, and a center portion in the vehicle width direction in the lower body is the floor tunnel portion. Is reinforced as a stringer.

In recent years, in the lower body structure of a vehicle body, particularly the lower body structure of a relatively large vehicle such as a minivan, the central part in the vehicle width direction has been reinforced further from the viewpoint of improving load dispersion at the time of a front collision and lower vehicle body rigidity. It is in. As one of such reinforcing structures, for example, as shown in Patent Document 1, a pair of left and right sides disposed on both sides in the vehicle width direction of the floor tunnel portion and extending in the vehicle front-rear direction substantially parallel to the side frame. A lower body structure provided with a center frame has been proposed.
Japanese Patent Laid-Open No. 2003-137136 (see FIG. 8)

  According to the lower vehicle body structure disclosed in Patent Document 1, the load at the time of a front collision is transmitted to the pair of left and right center frames to improve the load dispersion, and the center frame improves the rigidity of the lower vehicle body. On the other hand, since it is necessary to provide a new center frame corresponding to at least the body side frame of the side frame, there is a disadvantage in that not only the vehicle weight increases significantly, but also the manufacturing cost increases.

  In particular, in a relatively long vehicle, the center frame is formed to be relatively long, and the inconvenience of increased vehicle weight and increased cost appears remarkably.

  In this case, it may be possible to divide the center frame back and forth and arrange the divided parts at appropriate intervals. In this case, the load dispersibility and Although the lower vehicle body rigidity can be improved, the function as a longitudinal member is greatly reduced or lost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an automobile lower body structure that can suppress the increase in weight and cost as much as possible while ensuring the function as a stringer. It is said.

  In order to solve the above-described problem, a lower body structure of an automobile according to the present invention includes a pair of left and right side frames extending in the vehicle front-rear direction, and a pair of left and right sides disposed between the side frames in the vehicle front-rear direction. The center frame is divided in the vehicle front-rear direction, the divided frames are separated from each other in the vehicle front-rear direction, and the front and rear divided frames are connected by a seat support frame that supports the seat. It is characterized by this.

  According to the present invention, since the center frame is divided in the vehicle front-rear direction and these divided frames are spaced apart from each other in the vehicle front-rear direction, the center frame is not divided and is extended in the vehicle front-rear direction. Thus, an increase in weight and an increase in manufacturing cost can be suppressed as much as possible. Moreover, since the divided frames that are divided and spaced apart in the vehicle front-rear direction are connected by a seat support frame that supports a seat disposed in the vehicle interior, the center frame as a longitudinal member is provided between the divided frames. The missing portion can be replaced by an existing seat support frame, and the missing portion can be compensated for, so that load dispersibility during a front collision can be improved and rigidity of the lower vehicle body can be improved. That is, the function of the center frame as a longitudinal member can be secured as much as possible.

  The divided frames are connected by a seat support frame in a state where an axis extending in the vehicle front-rear direction and an axis extending in the front-rear direction of the seat support frame are biased. That is, since the divided frame is connected by the seat support frame at a position deviated from an axial center extending in the vehicle longitudinal direction, the divided frames are connected by matching the longitudinal axes of the divided frame and the seat support frame. Compared with the case where it was made, the transmission efficiency of a load can be reduced in a connection part, the shock absorbing effect can be acquired, and the impact transmitted to a rear divided frame can be reduced.

  The fuel tank is supported by the rear divided frame among the front and rear divided frames connected by the seat support frame. In other words, when the split frames are connected by biasing the longitudinal axis between the split frame and the seat support frame, the impact transmitted to the rear split frame can be reduced. By supporting the fuel tank on the frame, the fuel tank can be stably supported.

  Specifically, the rear divided frame is further divided into front and rear, and the second seat corresponding to the divided portion at a position where the front and rear divided frames are biased upward from an axis extending in the vehicle longitudinal direction. The fuel tank is configured to be connected by a support frame, and a part of the fuel tank is disposed between the front and rear divided frames.

  With this configuration, the center frame can be further divided and disposed, and an increase in vehicle weight and manufacturing cost can be effectively suppressed, and after being connected by the second seat support frame. A part of the fuel tank can be disposed in this space using the space between the front and rear divided frames, and the capacity of the fuel tank can be increased accordingly.

Here, a full flat panel may be used for the floor panel used in the lower vehicle body structure, but it is preferable to use a floor panel provided with a tunnel portion extending in the vehicle front-rear direction. center frame is not preferable being arranged in the vehicle width direction on both sides of the tunnel portion.

  If comprised in this way, the tunnel part of a floor panel will also function as a longitudinal member, and while being able to improve the rigidity of a lower body structure further, the load at the time of a front collision etc. can be distributed more effectively. .

In the present invention, a tire cross pan is provided with a rear cross member connected to the rear end of the center frame between the left and right side frames along the vehicle width direction, and a spare tire is stored behind the rear cross member. And is attached to the rear cross member so that the last row seat partially overlaps with the tire pan in plan view, and the seat support frame of the last row seat extends in the vehicle width direction so as to straddle the upper side of the tire pan. cross seat frame forming a closed cross section extending, provided with a reinforcing member for connecting the cross seat frame and the said rear cross member in the vehicle width direction central portion is not preferable.

  According to this configuration, the last row seat can be disposed regardless of the presence of the tire pan, the degree of freedom in layout of the last row seat can be improved, the rear cross member, the cross seat frame, and The vehicle body rigidity at the rear part of the lower vehicle body can be improved by the reinforcing member.

  According to the lower body structure of the automobile of the present invention, an increase in weight and an increase in manufacturing cost can be suppressed as much as possible as compared with a conventional structure that extends in the vehicle longitudinal direction without dividing the center frame. In addition, even though the center frame is spaced apart as a divided frame, there is an advantage that the function as a longitudinal member can be secured as much as possible by effectively using the existing seat support frame. is there.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an outline of an automobile according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing the lower body structure of the automobile, and FIG. 3 is a plan view showing the lower body structure with the floor panel removed.

  This automobile is of a so-called minivan type having seats 4 to 6 in the first to third rows in the longitudinal direction of the vehicle, and these seats 3 to 5 are arranged on the floor panel 7. As shown in FIGS. 1 and 2, a tunnel portion 8 having a predetermined width extending in the vehicle front-rear direction protrudes upward from the center portion of the floor panel 7 in the vehicle width direction. The tunnel portion 8 is formed such that the front end portion is inclined downward and the intermediate portion and the rear end portion are set to have a relatively small amount of upward protrusion (see FIGS. 7 and 8). ), Thereby preventing the passenger from moving in the passenger compartment.

  The rear portion of the floor panel 7 is formed with a tire pan 30 that accommodates a spare tire with a center portion in the vehicle width direction recessed downward. The front end edge of the tire pan 30 is curved along the outer peripheral shape of the spare tire.

  Further, both ends of the floor panel 7 in the vehicle width direction are joined to the inner side surfaces of a pair of left and right side sills 9 extending in the vehicle front-rear direction. Although not shown, the side sill 9 has a closed cross section that extends in the vehicle front-rear direction by an inner panel and an outer panel, and is configured as a strength member that extends in the vehicle front-rear direction. Further, a pair of left and right side frames 10 extending in the vehicle longitudinal direction are joined to the lower surface of the floor panel 7. Specifically, the side frame 10 is formed in a substantially inverted hat shape in cross section (not shown), and is joined to the lower surface of the floor panel 7 by spot welding or the like at a flange portion 10a (see FIG. 3) at the upper end thereof. Yes. The side frame 10 is configured as a through member that extends in the vehicle front-rear direction by connecting a front side frame 11, a body side frame 12, and a rear side frame 13 that extend in the vehicle front-rear direction, respectively. As shown in FIG. 2, the front side frame 11 is formed with a front kick-up portion 11a that is inclined forward and the rear side frame 13 is formed with a rear kick-up portion 13a that is inclined backward and upward. Yes.

  Between these side frames 10, a plurality of (seven in this embodiment) cross members 14 to 20 are installed along the vehicle width direction and between the side frames 10. A pair of left and right center frames 21 are disposed along the vehicle longitudinal direction on both sides of the portion 8 in the vehicle width direction.

  The first to seventh cross members 14 to 20 are each formed in an inverted hat shape when viewed in cross section, and are joined to the lower surface of the floor panel 7 at upper end joining flange portions 14a to 20a. The first cross member 14 is installed between the front end portions of the center frame 21, and both end portions thereof are joined to the center frame 21, specifically, a first divided frame 22 described later. On the other hand, the second cross member 15 to the seventh cross member 20 are provided with joint margins (not shown) at both ends so as to be expanded, and spot welding or the like is performed on the inner surface of the side frame 10 at the joint margin. It is joined. These first to seventh cross members 14 to 20 are arranged to be separated from each other in the vehicle front-rear direction. As shown in FIG. 2, the seventh cross member 20 is disposed on the vehicle front side of the tire pan 30, and the rear end portion thereof is curved so as to correspond to the front end portion shape of the tire pan 30. Further, between the side frame 10 and the side sill 9, first to sixth connection members 31 to 36 are arranged corresponding to the arrangement positions of the first to sixth cross members 14 to 16, respectively.

  The center frame 21 is disposed from the rear end portion of the front kick-up portion 11 a of the front side frame 11 to the rear end portion of the rear kick-up portion 13 a of the rear side frame 13. As shown in FIG. 7, the center frame 21 is formed in a reverse hat shape in cross section, and is joined to the lower surface of the floor panel 7 by spot welding or the like at the upper end joining flange portion 21 a. A closed cross section extending in the vehicle front-rear direction is formed. Further, as clearly shown in FIGS. 1 to 3, the center frame 21 is divided in the vehicle front-rear direction, and a plurality of these (three in the present embodiment) divided frames 22 to 24 are mutually connected in the vehicle front-rear direction. The divided frames 22 to 24 are arranged apart from each other and are connected in the vehicle front-rear direction by seat support frames 25 to 27 that support the seats 4 to 6 on the vehicle body.

  Specifically, the center frame 21 is divided at positions corresponding to the first row seat 4 and the second row seat 5 in the vehicle front-rear direction, and the first to third divided frames 22 which are parts after the division. ˜24 are main constituent members. Since the center frame 21 is disposed symmetrically about the tunnel portion 8, only one (the vehicle right side portion in FIG. 2) will be described here.

  As shown in FIGS. 2 and 3, the first divided frame 22 is formed such that the front end portion is curved and the front end edge is directed outward in the vehicle width direction. The first divided frame 22 has a front end joined to the inner surface of the rear end of the front kick-up portion 11 a of the side frame 10 and a rear end joined to the front end of the second cross member 15. The joining structure of the first divided frame 22 is the same as the joining structure of the side frame 10 and the cross members 14 to 20 and is not clearly shown in the drawing. A joint allowance is provided by expanding, and in this joint allowance, the side frame 10 is overlapped on the inner side surface and the lower surface in the vehicle width direction or the front end surface and the lower surface of the second cross member 15, and the joint allowance is spot welded or the like. It is joined. The joint structure between the second and third divided frames 23 and 24 and the cross members 16 to 19 is similarly configured. 4 to 6, portions indicated by 22 a, 23 a, and 24 a are joint margins extending from the bottom walls of the divided frames 22 to 24 formed in a reverse hat shape in cross section in the joint margins. The joint allowance extended from is not shown.

  As clearly shown in FIGS. 1 to 3, the front and rear end edges of the second divided frame 23 are joined to the rear end face of the third cross member 16 and the front end face of the fourth cross member 17, respectively. That is, the second divided frame 23 is disposed away from the first divided frame 22 by the gap between the second and third cross members 15 and 16.

  As shown in FIG. 4, the second divided frame 23 and the first divided frame 22 include a first seat support frame 25 as a seat base that supports the first seat 4 via the first row seat rail member 37. Are connected by As shown in FIGS. 4 and 9, the first seat support frame 25 includes a pair of left and right support legs 38 disposed in the vehicle front-rear direction, and a connection that connects the pair of support legs 38 in the vehicle width direction. The arm portion 39 is provided, and is formed in a substantially H shape in plan view. A flange portion (not shown) is formed on the first support frame 25 by appropriately folding the peripheral portion downward or upward, thereby forming a strength member.

  Each support leg 38 is bent so that the middle part in the longitudinal direction protrudes upward, and is attached to the lower vehicle body at both longitudinal front and rear ends. Specifically, as shown in FIG. 4, the support leg portion 38 on the inner side in the vehicle width direction (the tunnel portion 8 side) has a gusset plate 40 and a floor panel 7 whose front end portion is mounted on the second cross member 15. Are joined to each other by a bolt 43 and a pin 44, and a rear end portion thereof is joined to an upper end joining flange portion 16 a of the third cross member 16, a gusset plate 41 attached to the third cross member 16, and the floor panel 7 by a bolt 45. It is joined. On the other hand, as shown in FIG. 9, the support leg 38 on the outer side in the vehicle width direction (side sill 9 side) has a front end portion attached to the gusset plate 42 and the floor panel 7 mounted on the second connecting member 32, and a bolt 46 and While being joined by the pin 47, the rear end part is joined to the upper wall of the side sill 9 by the bolt 48.

  In other words, the first and second divided frames 22 and 23 are supported by the first seat support frame 25, particularly the support leg portion 38 disposed on the inner side in the vehicle width direction via the second and third cross members 15 and 16 and the like. Are connected in the vehicle longitudinal direction. Further, as shown in FIG. 4, the first seat support frame 25 is arranged so as to bridge between the first and second divided frames 22 and 23 in an arch shape. The first and second divided frames 22 and 23 are connected to each other at positions displaced upward from the axial centers 22L and 23L extending in the vehicle front-rear direction.

  The first seat support frame 25 is provided on the left and right sides of the tunnel portion 8, and a seat rail member 37 is supported on each first seat support frame 25, and a first rail is supported on the seat rail member 37 via a slider. The seat cushion of the one-row seat 4 is supported.

  Returning to FIGS. 1 to 3, the front and rear end edges of the third divided frame 24 are joined to the rear end face of the fifth cross member 18 and the front end face of the sixth cross member 19, respectively. That is, as shown in FIG. 5, the third divided frame 24 is disposed away from the second divided frame 23 by the gap between the fourth and fifth cross members 17 and 18.

  The third divided frame 24 and the second divided frame 23 are connected in the vehicle front-rear direction by a second seat support frame 26 as a seat rail member that supports the second row seat 5 so as to be slidable back and forth. As shown in FIGS. 5 and 10, the second seat support frame 26 is appropriately disposed along a pair of left and right rail bodies 49 disposed in the vehicle front-rear direction and the longitudinal direction of each rail body 49. In this embodiment, the rail body 49 is attached to the lower vehicle body by means of the attachment flange portions 50a to 50h. Each of the mounting flange portions 50a to 50h has a flange portion 51 formed by folding both ends in the width direction, and the mounting strength of the second seat support frame 26 to the vehicle body is improved.

  The rail body 49 extends in the vehicle front-rear direction and has a cross section orthogonal to the longitudinal direction formed in a substantially C shape, and a lower end portion of the slider 52 that is formed in a reverse T shape in cross section can slide back and forth. , And is supported in a lockable manner at a predetermined position. Of the pair of left and right rail bodies 49, the rail body 49 disposed on the inner side in the vehicle width direction has mounting flange portions 50a to 50a on the outer side of the front end, the inner and outer sides near the rear of the center, and the inner and outer sides of the rear end. 50e is provided.

  And the rail main body 49 arrange | positioned inside this vehicle width direction is as shown in FIG.5 and FIG.10, and the front-end part is the upper end joining flange part of the 4th cross member 17 by each mounting flange part 50a-50e. 17a and the floor panel 7 are joined to each other by a bolt 53, and at the center thereof, the upper end joining flange 18a of the fifth cross member 18 and the floor panel 7 are joined to each other by a bolt 54. The upper end joint flange portion 21 a and the floor panel 7 are joined by bolts 55. A reinforcing member 56 is mounted in the third divided frame 24 at a position where the second seat support frame 26 is attached to the third divided frame 24 in order to improve the attachment strength. The rail body 49 is provided with a stopper (not shown) for regulating the sliding movement amount of the slider 52.

  On the other hand, as shown in FIG. 10, the rail body 49 disposed on the outer side in the vehicle width direction is provided with mounting flange portions 50f to 50h on the inner side of the front end portion, the outer side of the rear portion of the center portion, and the inner side of the rear end portion. It has been. The rail main body 49 disposed on the outer side in the vehicle width direction has a front end at the flange portion 10a and the floor on the inner side in the vehicle width direction of the side frame 10 (particularly, the body side frame 12) by the mounting flange portions 50f to 50h. It is joined to the panel 7 and joined to the flange portion 10a and the floor panel 7 on the outer side in the vehicle width direction of the side frame 10 (particularly, the body side frame 12) at the intermediate portion, and at the rear end portion, the side frame 10 (In particular, the upper side wall of the rear side frame 13 and the floor panel 7 are joined.

  That is, the second and third divided frames 23, 24 are provided by the second seat support frame 26, particularly the rail main body 49 disposed on the inner side in the vehicle width direction via the third and fourth cross members 17, 18 and the like. It is connected in the vehicle longitudinal direction. Further, as shown in FIG. 5, the second seat support frame 26 is disposed on the second and third divided frames 23, 24, and spans between the frames 23, 24 at the upper part thereof to form each divided frame. 23 and 24 are connected at positions offset upward from axial centers 23L and 24L extending in the vehicle longitudinal direction.

  The second seat support frames 26 are provided on the left and right sides of the tunnel portion 8, and the seat cushions of the second row seats 5 are supported by the second seat support frames 26 via the sliders 52.

Further, as shown in FIG. 6, the sixth cross member 19 (corresponding to an example of the rear cross member) to which the rear end portion of the third divided frame 24, in other words, the rear end portion of the center frame 21 is connected, A front end portion of the third row sheet 6 which is a row sheet is attached via a gusset plate 57 and a floor panel 7 attached on the sixth cross member 19 .

  Specifically, the third row seat 6 is a so-called bench seat in which the movement in the vehicle front-rear direction is restricted and the seat cushion 6a is integrally formed in the vehicle width direction, and the rear end portion is the seventh. It arrange | positions so that it may overlap with the tire pan 30 arrange | positioned behind the cross member 20 in planar view. As shown in FIG. 11, the third seat support frame 27 that supports the third row seat 6 includes a pair of left and right support legs 58 that extend in the longitudinal direction of the vehicle and are disposed on the rear side frame 13, and the support legs. A cross frame 59 (corresponding to an example of a cross seat frame) erected between the rear end portions of the portion 58 along the vehicle width direction, and the cross frame 59 and the sixth cross member 19 are connected at the center in the vehicle width direction. The third row seat 6 as a bench seat is attached to and supported by the lower vehicle body.

  The support leg 58 is curved and formed in an arch shape along the longitudinal direction, and is fastened to the upper surface wall of the rear side frame 13 by bolts 64 at both front and rear ends thereof. Although not shown, the support leg 58 is formed by expanding both ends in the width direction in a bead shape, thereby improving the rigidity of the support leg 58 itself.

  The cross frame 59 is disposed behind the seventh cross member 20, is laid between the support leg portions 58 so as to straddle the tire pan 30, and both ends are joined to the upper surface of the rear end portion of the support leg portion 58 by welding or the like. Has been. As shown in FIG. 6, the cross frame 59 is formed in a flat rectangular tube shape, thereby forming a closed cross section C extending in the vehicle width direction.

  As shown in FIGS. 6 and 11, the reinforcing member 60 is formed in an arch shape along the longitudinal direction, like the support leg portion 58. Further, the reinforcing member 60 is formed as a bead portion 61 having flange portions (not shown) standing on both sides in the width direction and a center portion in the width direction bulging upward, thereby improving rigidity. Yes. Further, the reinforcing member 60 is formed with the rear half portion widened, and the bead portion 61 is bifurcated in the widened portion 60a.

  The front end of the reinforcing member 60 is joined to the center of the sixth cross member 19 in the vehicle width direction by a bolt 62 via a gusset plate 57 attached to the sixth cross member 19 and the floor panel 7. The rear end portion is wound around the cross frame 59 from below and joined to the upper surface of the cross frame 59. Support members 65 and 66 for supporting the seat cushion 6a of the third row seat 6 protrude upward from the reinforcing member 60, and support the third row seat 6 serving as a bench seat at a substantially central portion in the vehicle width direction. It is made to do.

  The third row seat 6 is supported on the third seat support frame 27 having the above-described configuration via brackets 65, 66 and the like. That is, the third row seat 6 is attached to the sixth cross member 19 through the third seat support frame 27 and the rear end portion is attached to a predetermined position of the rear side frame 13. The third row seat 6 is formed by dividing the seat back in the vehicle width direction so that each seat back can be individually tilted.

  Meanwhile, a fuel tank 68 is supported by the pair of left and right center frames 21 so as to straddle the second divided frame 23 and the third divided frame 24. That is, the fuel tank 68 is held below the floor panel 7, the side frame 10, and the center frame 21 at a predetermined height position with respect to the road surface. FIG. 12 is a bottom view of the lower vehicle body structure in which the fuel tank is mounted.

  The fuel tank 68 is formed of a synthetic resin into a flat and substantially rectangular parallelepiped shape, and is configured to be mounted in a space between the floor panel 7 and the road surface. Specifically, the fuel tank 68 is formed to have a width substantially equal to that of the side frame 10 and a length from the front end portion of the second divided frame 23 to an intermediate portion of the third divided frame 24. Is set. A flange portion 69 is provided on the outer periphery of the fuel tank 68 so as to protrude outward. The flange portion 69 is formed at the intermediate portion in the height direction of the fuel tank 68 substantially horizontally over the entire circumference.

  As shown in FIG. 1, the upper surface wall of the fuel tank 68 is located between the fourth cross member 17 and the fifth cross member 18 including the gap between the second divided frame 23 and the third divided frame 24. In the space portion, it bulges upward, and the internal capacity is expanded for this bulge. That is, a bulging portion in which a part of the fuel tank 68 bulges is disposed between the second divided frame 23 and the third divided frame 24.

  As shown in FIG. 12, the fuel tank 68 is joined at its four corners, and is also supported at three points in the vehicle width direction at the front and rear thereof. That is, the fuel tank 68 is joined to the bottom wall portion of the side frame 10 by bolts 70 at the four corners of the flange portion 69, and the second and second flange portions 69 on the front and rear sides are respectively connected via the tank brackets 71. The third divided frames 23 and 24 are joined to the bottom wall by bolts 72. Thus, since the fuel tank 68 is supported by the second and third divided frames 23 and 24 that are spaced from the first divided frame 22, the load input to the first divided frame 22 is once increased. Since one seat support frame 25 is inputted, it is inputted to the second divided frame 23, and the impact based on the load inputted to the second divided frame 23 is in a relaxed state. It can be supported stably.

  According to the lower body structure of an automobile configured as described above, the center frame 21 is divided into three parts, and these first to third divided frames 22 to 24 are spaced apart in the vehicle front-rear direction. Compared to the conventional structure that is continuously extended in the vehicle longitudinal direction without dividing the frame, not only can the weight be reduced, but also the material cost can be saved by the distance between the divided frames 22-24. Manufacturing costs can be reduced. That is, an increase in weight and an increase in manufacturing cost can be suppressed as much as possible for the lower vehicle body structure not provided with the center frame.

  Thus, when the center frame 21 is divided and arranged apart from each other, the rigidity of the vehicle body can be improved and the impact load can be efficiently dispersed as compared with the lower vehicle body structure in which the center frame is not provided. However, compared to the conventional structure in which the center frame is continuously extended in the longitudinal direction of the vehicle, the function of the center frame as a longitudinal member may be impaired. That is, since the divided frames 22 to 24 are spaced apart from each other, the function as a longitudinal member may be reduced or eliminated, and the vehicle body rigidity and load dispersibility may be significantly reduced.

  However, according to the lower vehicle body structure of the present embodiment, the first and second seat support frames 25 and 26 that support the first row and second row seats 4 and 5 disposed in the vehicle interior are effectively used. Since the first to third divided frames 22 to 24 are connected in the vehicle front-rear direction by the first and second seat support frames 25 and 26, the first divided frame 22 and the second divided frame 23, Alternatively, the missing portion of the center frame 21 functioning as a longitudinal member between the second divided frame 23 and the third divided frame 24 can be replaced by the existing first and second seat support frames 25 and 26. It is possible to effectively reduce the decrease in rigidity or load transferability due to the portion, and the lower vehicle body despite the divided frames 22 to 24 being spaced apart. It is possible to improve the gender, thereby improving the load distribution of the front 突字 like. Moreover, the first and second seat support frames 25 and 26 are generally configured as strength members, and the center frame 21 can be reinforced by effectively using such strength members. That is, the function of the center frame 21 as a longitudinal member can be secured as much as possible.

  In summary, according to the lower body structure of the automobile of the present embodiment, the rigidity and load dispersibility are improved while suppressing an increase in weight and manufacturing cost as compared with the lower body structure in which the center frame is not provided. There is an advantage that both of them can be achieved, which cannot be achieved by the conventional structure. Moreover, since the tunnel portion 8 of the floor panel 7 is provided in the vehicle front-rear direction, further improvement in rigidity and load dispersibility of the lower vehicle body is achieved.

  Moreover, according to the lower vehicle body structure of the present embodiment, the rigidity of the rear structure can be improved using the third seat support frame 27. That is, the sixth cross member 19 to which the rear end of the center frame 21 is connected between the side frames 10 is disposed along the vehicle width direction, and a tire that stores a spare tire behind the sixth cross member 19. A pan 30 is provided, and the third row seat 6 is attached to the sixth cross member 19 so as to partially overlap the tire pan 30 in a plan view. The seat support frame 27 of the third row seat 6 is attached to the tire pan 30. A cross frame 59 that forms a closed cross section C extending in the vehicle width direction so as to straddle the upper side of the vehicle, and a reinforcing member 60 that connects the cross frame 59 and the sixth cross member 19 at the center in the vehicle width direction. Regardless of the presence of the tire pan 30, the third row seat 6 can be disposed, and the degree of freedom in layout of the third row seat 6 is improved. It is possible, the sixth cross member 19, it is possible to improve the rear portion of the vehicle body rigidity of the lower vehicle body by the cross frame 59 and the reinforcing member 60.

  The vehicle body front structure described above is an embodiment of the structure according to the present invention, and the specific configuration of the structure can be appropriately changed without departing from the gist of the present invention. A modification will be described below.

  (1) In the above-described embodiment, the first seat support frame 25 disengages the rear end portion of the first divided frame 22 and the front end portion of the second divided frame 23 upward from the axis 22L, 23L of each frame 22, 23. And the second seat support frame 26 has the rear end of the second divided frame 23 and the front end of the third divided frame 24 upward from the axial centers 23L, 24L of the frames 23, 24. Although the connection is performed at a disengaged position, the connection mode of the divided frames by the seat support frame is not limited to that of the above embodiment.

  For example, the seat support frame is arranged in such a manner as to linearly connect the axial centers 22L to 24L of the front and rear divided frames 22 to 24, and the divided frames arranged in the front and rear are connected by the seat support frame. You may do it. Even if comprised in this way, the missing part of a center frame can be compensated effectively using a seat support frame, and vehicle body rigidity and load dispersibility can be improved.

  However, when configured as in the above embodiment, the first and third divided frames 22 to 24 and the first and second seat support frames 25 and 26 are connected so as to continuously connect the front and rear axial centers. Compared to the above, it is possible to obtain a buffering effect by reducing the load transmission efficiency at the connecting portion, and the rear divided frame, that is, the second divided frame 23 with respect to the first divided frame 22 or the third divided frame 23 with respect to the second divided frame 23. This is advantageous in that the impact transmitted to the divided frame 24 can be reduced.

  (2) Although the floor panel 7 provided with the tunnel portion 8 is used in the above embodiment, the present invention can also be applied to a full flat floor panel not provided with the tunnel portion. In this case, since the longitudinal member as the tunnel portion is not provided at the center in the vehicle width direction, the significance of providing the center frame as the longitudinal member is improved.

  Further, the tunnel portion may be provided in a part of the vehicle front-rear direction, and unlike the above-described embodiment, the tunnel portion is provided at a substantially constant height in the vehicle front-rear direction. May be.

  (3) In the above-described embodiment, the seat pedestal portion that supports the first row seat 4 and the seat rail member 26 that supports the second row seat 5 are used as the seat support frame. The specific configuration is not particularly limited as long as the frame supports the seat with respect to the vehicle body.

  (4) In the above embodiment, the third seat support frame 27 is integrally provided in the vehicle width direction. However, when the third row seat 6 is divided and configured in the vehicle width direction, The seat support frame may also be configured by being divided in the vehicle width direction. However, when the third seat support frame 27 is integrally provided as in the above embodiment, the rigidity at the rear portion of the lower vehicle body structure can be effectively improved.

  (5) In the above-described embodiment, the first and second seat support frames 25, 26 are provided in a pair on the left and right, but the left and right seat support frames 25, 26 are integrally formed. Also good.

1 is a schematic cross-sectional view of an automobile according to an embodiment of the present invention. It is a perspective view which shows roughly the lower vehicle body structure of the motor vehicle. It is a top view which shows the structure in the state which removed the floor panel. It is sectional drawing which expands and shows the 1st row sheet | seat periphery part of FIG. It is sectional drawing which expands and shows the 2nd row sheet | seat peripheral part of FIG. It is sectional drawing which expands and shows the 3rd row sheet | seat periphery part of FIG. It is the VII-VII sectional view taken on the line of FIG. It is the VIII-VIII sectional view taken on the line of FIG. FIG. 4 is an enlarged plan view showing a peripheral portion of a first seat support frame in FIG. 3. FIG. 4 is an enlarged plan view showing a peripheral portion of a second seat support frame in FIG. 3. FIG. 4 is an enlarged plan view showing a peripheral portion of a third seat support frame in FIG. 3. It is a bottom view which shows the lower vehicle body structure of a motor vehicle including a fuel tank.

4-6 First to third row seats 7 Floor panel 8 Tunnel portion 10 Side frame 14-20 First to seventh cross members 21 Center frame 22-24 First to third divided frames 22L-24L Axes 25- 27 First to third seat support frames 30 Tire pan 59 Cross frame 60 Reinforcement member 68 Fuel tank C Closed section

Claims (3)

A pair of left and right side frames extending in the vehicle front-rear direction, and a pair of left and right center frames disposed in the vehicle front-rear direction between these side frames,
The center frame is divided in the vehicle front-rear direction so that the divided frames are spaced apart from each other in the vehicle front-rear direction, and the front and rear divided frames support the seat at a position offset from an axis extending in the vehicle front-rear direction. Linked by the support frame,
Of the front and rear divided frames connected by the seat support frame, the rear divided frame is further divided into front and rear, and the front and rear divided frames are divided at positions where they deviate upward from the axial center extending in the vehicle longitudinal direction. configured to be coupled by the second seat supporting frame corresponding to the portion, the lower vehicle body structure, wherein a portion of the fuel tank is disposed between the front and rear divided frame of the rear side .   The lower body of an automobile according to claim 1, further comprising a floor panel provided with a tunnel portion extending in the vehicle front-rear direction, wherein the center frame is disposed on both sides of the tunnel portion in the vehicle width direction. Construction.   A rear cross member to which the rear end of the center frame is connected between the left and right side frames is disposed along the vehicle width direction, and a tire pan for storing a spare tire is provided behind the rear cross member, The last row seat is attached to the rear cross member so as to partially overlap with the tire pan in a plan view, and the seat support frame of the last row seat extends in the vehicle width direction so as to straddle the tire pan. 3. A lower vehicle body of an automobile according to claim 1, further comprising: a cross seat frame that forms a cross seat frame; and a reinforcing member that connects the cross seat frame and the rear cross member at a central portion in the vehicle width direction. Construction.

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