JP3381404B2 - Car body floor structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile body floor structure.

[0002]

2. Description of the Related Art FIGS. 9 to 13 show different examples of conventional vehicle body floor structures. In the structures shown in FIGS. 9 and 10, on a floor panel 21 and on side sills 23 on both sides of the floor panel. At the position where the center pillars (not shown) that are joined together are offset from the standing position in the front-rear direction, with the floor tunnel 22 at the center of the floor panel in the middle, the third inner wall having a substantially U-shaped cross section extends across the sill inner 23a and the side wall 22a of the floor tunnel 22. The cross members 24, 24 are aligned and joined in a straight line in the vehicle width direction.

Further, a tunnel reinforcement 25 is arranged along the inside of the floor tunnel 22 so as to join the side wall 22a of the floor tunnel 22 and the tunnel reinforcement 25.
The rear end portion of the seat slide rail 26 on the floor center side is fixed to the overlapping portion with the bolt and nut 27 via the bracket 26a.

In the structure shown in FIGS. 11 and 12, the sill inner 23a and the floor tunnel 22 are formed on the lower surface of the floor panel 21 at a position offset from the standing position of the center pillar (not shown) in the front-rear direction as described above. The third cross members 24, 24 having a substantially U-shaped cross section are arranged in a line in the vehicle width direction so as to be aligned and joined to each other over the bending base, and are directed upward to a portion of the floor panel 21 where the third cross member 24 is arranged. The recess 21a is bulged to enlarge the closed cross-sectional area of the portion where the third cross member is disposed.

A mount member 28 at the rear end of the seat slide rail (see FIG. 9) is joined and arranged in a closed cross section formed by the floor panel 21 and the third cross member 24, and the seat is mounted on the mount member 28. The slide rail is attached and the third cross member 24
A receiving portion 30 for accommodating the pipes 29 is recessed in the front and rear direction toward the upper side on the lower surface of the receiving portion 30, and the receiving portion 30 straddles the receiving portion 30.
A holder 31 for holding the pipes 29 accommodated therein is attached by bolts and nuts 32.

The structure shown in FIG. 13 has a lower end of a tunnel reinforcement 25 arranged along the inner side of the floor tunnel 22 at a position offset in the front-rear direction from a third cross member (see FIG. 9 or 11) which is not shown. The tunnel stay 33 is attached by bolts and nuts 34 across the parts, and the floor stay 22 is attached by the tunnel stay 33.
The so-called opening deformation, that is, the so-called mouth opening deformation is prevented.

These similar structures are described in, for example, Shokai Sho 63-.
No. 119485, etc.

[0008]

Problems to be Solved by the Invention FIGS. 9, 10 and 1
Although the conventional structures shown in FIGS. 1 and 12 each include the third cross member 24 to enhance the surface rigidity of the floor panel 21, the left and right third cross members 24 and 24 do not have continuity, and the third cross members 24 and 24 are not continuous. Since there is no continuity between the cross members 24, 24 and the center pillar (not shown) which is a vertical frame member, the floor panel 21 flexes and vibrates in the vertical direction when the vehicle is running, and a vibration noise generally referred to as drumming is generated. It tends to occur.

Further, in the structure shown in FIG. 13, the opening stay deformation of the floor tunnel 22 is partially suppressed by the tunnel stay 33, so that the effect of preventing the drumming can be expected, but the tunnel stay 33 and the third cross member 24 are expected. It is not possible to thoroughly prevent drumming due to lack of continuity with.

Moreover, in any of the conventional structures described above,
As described above, since there is no continuity between the left and right third cross members 24, 24, and the third cross members 24, 24 and the center pillar (not shown), the third cross members 24, 24 against a side collision of the vehicle. In order to fully exert the beam function of (1), a dedicated reinforcing member is required, which is disadvantageous in terms of cost and weight.

Therefore, the present invention provides a vehicle body floor structure capable of preventing drumming caused by vibrations of a vehicle while running and taking thorough countermeasures for side collision without using a dedicated reinforcing member. is there.

[0012]

According to a first aspect of the present invention, the central floor tunnel is located on the floor panel, and the sill inners of the side sills on both sides of the floor panel and the side walls of the floor tunnel are substantially U-shaped in cross section. of the structure formed by joining disposed third cross member in the vehicle width direction, and disposed in the third cross-member attached to the side sill with the center pillar of the upright position and on the same vehicle width direction line, this Furoapa
The third cross member arrangement portion joined on the flannel surface is
Third cross member and floor panel on the bottom side in the vehicle width direction
It has a closed cross section with a concave section that is recessed toward
A cross section of the concave part that is recessed in the vehicle width direction toward the lower side
It is formed in a triangular shape, and the top of the floor plan
Formed by inclining backward from the flannel side to the side sill side
At the same time, the tunnel stay is connected to the lower surface of the floor panel across the floor tunnel and on the same vehicle width direction line as the third cross member.

[0013]

[0014] In the second aspect, it is inclined forming an upper wall of the third cross member rearwardly downwards joined on full <br/> lower panel surfaces of claim 1.

[0015]

According to a third aspect, the first and second aspects are described.
On the lower surface of the recess formed by denting the floor panel in the vehicle width direction toward the lower side, the receiving portion of the pipes is recessed toward the upper side in the front-rear direction. The holder part for holding the pipes accommodated in the is extended.

In a fourth aspect, the first to third aspects are described.
The connecting position of the tunnel stay, which is connected to the floor panel of the above-mentioned floor panel across the floor tunnel, with the floor panel is set on substantially the same longitudinal line as the seat slide rail attachment position on the third cross member.

In a fifth aspect, the first to fourth aspects are described.
Of the floor tunnel sidewall to form a ledge which bulges toward the side of, while bonding by polymerizing the upper wall of the third cross member on the shelf portion, the lower surface of the front Symbol ledge tunnel stay A folding portion that overlaps is formed, and a seat slide rail is attached to the overlapping portion of the upper wall of the third cross member with the shelf portion and the bending portion.

[0019]

According to the first aspect of the invention, the left and right third cross members are continuous through the tunnel stay, and the third cross members are continuous with the center pillar in the vehicle width direction. The member, the tunnel stay, and the center pillar are almost integrated in the vehicle width direction, and the function of preventing the opening of the floor tunnel by the tunnel stay and the beam function of the third cross member can be fully exerted, and the surface rigidity of the floor panel. It is possible to prevent the flooring from being drummed due to the vibration of the vehicle while the vehicle is running.

In addition, since the center pillar, the left and right third cross members and the tunnel stays are aligned and continuous in the vehicle width direction in this manner, the beam function of the third cross member can be sufficiently exerted. At the time of a side collision, the third cross member and the tunnel stay sufficiently oppose the collision load, and the collision load is linearly transmitted not only to the side sill on the other side but also to the center pillar to disperse the load on the body frame member. Is performed satisfactorily, and the deformation of the floor panel can be suppressed to a small extent to secure a living space in the passenger compartment.

Further, since the area of the closed cross section formed by the third cross member and the floor panel can be enlarged by the recessed portion provided in the floor panel, the beam rigidity of the third cross member can be increased and the formation of the recessed portion can be achieved. As a result, the surface rigidity of the floor panel is enhanced, and it is possible to thoroughly prevent drumming and prevent side collisions. And further, the vehicle
The airflow that flows along the bottom surface of the floor panel during driving is
Inclination of the top of the recess protruding in the vehicle width direction on the lower panel lower surface
Along the floor to the side of the floor in a backward slanted direction with a straightening guide
Can improve the aerodynamic characteristics of the bottom surface of the floor panel.
It

According to the second aspect , since the upper wall of the third cross member is formed so as to be slanted downward and rearward, the rear seat occupant can smoothly put his / her foot on the upper wall of the slanted third cross member. The third cross member can be effectively used as a footrest, and the third cross member can be remarkably enhanced in habitability around the feet of the rear seat occupant without being an obstacle.

[0023]

According to the third aspect , the pipes can be accommodated in the receiving portion even in the recessed portion forming portion of the floor panel and arranged along the lower surface of the floor panel, and the pipes project downward in the recessed portion forming the road surface interference. It is possible to avoid this and to hold the pipes by the holder portion of the tunnel stay, so that the number of clamps can be reduced and the cost can be reduced.

According to claim 4, since the binding position of the tunnel stay of the floor panel is set on a seat slide mounting position substantially the same longitudinal direction line on a third cross member, mounting rigidity of the seat slide rails It is possible to improve the support stability of the sheet.

According to claim 5, since the seat slide seal is attached to the overlapping portion of the upper wall of the third cross member, and the shelf portion of the floor tunnel side wall, and the bent portion of the tunnel stay, of the seat slide rails The mounting rigidity can be increased and the support stability of the seat can be improved.

Further, since the side wall bulging is formed on the side wall of the floor tunnel, when the floor tunnel is deeply drawn at the time of press molding of the floor panel, the shelf should be a multistage drawing. As a result, wrinkles and cracks do not occur in the floor tunnel molding base due to deep drawing, and the quality and manufacturing yield can be improved.

[0028]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIGS. 1 to 7, reference numeral 1 denotes a floor panel in which a floor tunnel 2 is bulged and formed in a central portion of the floor tunnel 2.
Both ends thereof are joined to a sill inner 3a of a side sill 3 which is a skeleton member in the front-rear direction of the vehicle body on the floor side.

Reference numeral 4 denotes a third cross member disposed on the floor panel 1 with the central floor tunnel 2 in the middle so as to be joined in the vehicle width direction across the sill inner 3a and the side wall 2a of the floor tunnel 2. Reference numeral 4 denotes a substantially U-shaped cross section, and flanges 4c formed by bending the edges of the front and rear side walls 4b and the edges of the left and right side ends are provided on the floor panel 1, the side wall 2a of the floor tunnel 2 and the sill inner 3a. They are polymerized and joined by spot welding.

The third cross member 4 is jointed and arranged on the same vehicle width direction line as the standing position of the center pillar 5, which is a frame member in the vertical direction of the vehicle body joined to the side sill 3, and in this embodiment, the floor panel. In FIG. 1, a concave portion 6 is provided so that the portion where the third cross member 4 is disposed is directed downward in the vehicle width direction to enlarge the area of the closed cross section formed by the third cross member 4 and the floor panel 1. is there.

As shown in FIGS. 2 to 4, the upper wall 4a of the third cross member 4 is formed so as to be slanted rearward so that the upper wall 4a can be effectively used as a footrest by a passenger in the rear seat.

The recess 6 of the floor panel 1 is formed in a triangular shape in cross section as shown in FIGS. 2 to 5, and the top 6a of the recess 6 is seen from the floor tunnel 2 side to the side sill 3 side. It is formed so as to be inclined rearward toward the rear.

Reference numeral 7 denotes a plate-like tunnel stay which is connected to the lower surface of the floor panel 1 across the floor tunnel 2.
The tunnel stay 7 is arranged on the same vehicle width line as the third cross members 4, 4.

Both ends of the tunnel stay 7 are formed in the same sectional shape as the recess 6 of the floor panel 1, and the front and rear edges of the ends of the tunnel stay 7 are externally fitted to the lower surface of the recess 6 so that the bolt 1 will be described later.
5, it is fastened and fixed to the floor panel 1 by nuts 14.

On the lower surface of one recess 6 of the floor panel 1, a receiving portion 8 is recessed upward in the front-rear direction.
Pipes 9 arranged in the front-back direction on the lower surface of the floor panel 1
Is accommodated in the receiving portion 8 so that the pipes 9 can be arranged along the lower surface of the floor panel 1 without protruding downward even in the portion where the recess 6 is formed.

Plural places of the pipes 9 are fixed to the lower surface of the floor panel 1 by clamps (not shown). In this embodiment, one end of the tunnel stay 7 has a holder portion 7a extending below the receiving portion 8. This holder part 7 is extended in a flat plate shape.
The pipes 9 accommodated in the receiving portion 8 are held by a.

A reinforcing bead 10 is formed in the front and rear direction on the floor panel 1 so as to intersect with the recess 6 and project downward, and a pipe 9 is provided on the side of the bead 10 on the floor center side. The bead 10 is effectively arranged as a protector so that the pipes 9 can be protected from road surface interference.

Reference numeral 11 denotes a seat slide rail of the front seat 12, and the seat slide rail 11 has a second cross member 13 having a substantially L-shaped cross section, which is arranged on the floor panel 1 across the floor tunnel 2 so as to be joined to the front tunnel 12. The second cross member 13 and the upper wall 4a of the third cross member 4 are placed so as to straddle the third cross member 4.
Bolts 17, 17 are screwed and attached to the nuts 16, 16 joined to.

Here, the front and rear edges of the tunnel stay 7 are provided with the flange 4 of the front and rear wall 4b of the third cross member 4.
A bolt 15 is inserted through the floor panel 1 and screwed into a nut 14 which is joined and arranged to the c, and the fastening point is fixed by fastening the bolt 15 and the nut 14 to the above-mentioned seat slide rail 11 on the floor center side. It is set so as to be aligned on the same front-rear direction line as the connecting point of the bolt 17 and the nut 16 on the third cross member 4.

In FIGS. 1 and 6, reference numeral 18 denotes a tunnel reinforcement which is joined and arranged from the upper wall 4b of the floor tunnel 2 to the upper portion of the side wall 4a.

According to the structure of the above embodiment, the left and right third cross members 4, 4 joined and arranged on the floor panels 1 on both sides of the floor tunnel 2 are continuous through the tunnel stay 7, and these third cross members are also connected. The members 4 and 4 are substantially integrated with the center pillars 5 and 5 in the vehicle width direction so that the tunnel stay 7 can sufficiently exhibit the opening prevention function of the floor tunnel 2 and the beam function of the third cross members 4 and 4. As a result, the surface rigidity of the floor panel 1 can be remarkably enhanced, and the drumming of the floor panel 1 due to the vibration during traveling of the vehicle can be reliably prevented.

Further, as described above, the center pillars 5, 5
The left and right third cross members 4 and 4 and the tunnel stay 7 are aligned in the vehicle width direction and continuously, so that the beam function of the third cross members 4 and 4 can be sufficiently exerted. At times, the third cross members 4 and 4 and the tunnel stay 7 sufficiently oppose the collision load, and the collision load is linearly transmitted not only to the side sill 3 on the other side but also to the center pillar 5 so that the load is applied to the vehicle body frame member. Is satisfactorily distributed, so that the deformation of the floor panel 1 can be suppressed to be small and a living space can be secured.

In particular, in this embodiment, the portion of the floor panel 1 in which the third cross members 4, 4 are arranged is formed as a recess 6 having a triangular cross section extending in the vehicle width direction, and the third cross members 4, 4 and the floor panel are formed. Since the area of the closed cross section formed by 1 and 1 is enlarged, the beam rigidity of the third cross members 4, 4 is enhanced, and the surface rigidity of the floor panel 1 is enhanced by the formation of the recessed portions 6 to prevent drumming and side surfaces. You can take thorough countermeasures against collisions.

The cross section formed on the floor panel 1
The triangular recess 6 has a top portion 6a at the floor tunnel 2
Side to side sill 3 side, it is formed so as to be inclined rearward in a plan view, so that an air flow, which is a so-called underfloor flow, flowing from the front of the vehicle along the lower surface of the floor panel 1 during traveling of the vehicle is shown in FIG. As indicated by the arrow a, it is possible to deflect rearwardly to the floor side portion along the inclination of the top portion 6a and guide the straightening, and to improve the aerodynamic characteristics of the lower surface of the floor panel.

On the other hand, the upper wall 4 of the third cross member 4
Since a is inclined downwardly and rearwardly, a passenger in the rear seat can smoothly put his / her foot on the upper wall 4a, and the third cross member 4 can be effectively used as a footrest. Can be remarkably enhanced in habitability around the feet of the rear seat occupants without becoming an obstacle.

Further, the pipes 9 arranged on the lower surface of the floor panel 1 in the front-rear direction can be accommodated in the receiving portion 8 even at the portion where the concave portion 6 having a triangular cross section is formed and arranged along the lower surface of the floor panel 1. Since the pipes 9 can be prevented from projecting downward at the portion where the recess 6 is formed and interfering with the road surface, and the holder portion of the tunnel stay 7 can hold the pipes 9 accommodated in the receiving portion 8, the clamp The number can be reduced to reduce the cost .

In particular, if the reinforcing bead 10 projecting downward is formed on the floor panel 1 in the front-back direction as in this embodiment, and the pipes 9 are arranged along the side portion of the bead 10, The bead 10 functions as a protector and can protect the pipes 9 from road surface interference and the like.

Further, the floor panel 1 of the tunnel stay 7
Since the connecting positions of the bolts 15 and the nuts 14 are set on the same front-back direction line as the connecting positions of the bolts 17 and the nuts 16 on the third cross member 4 of the seat slide rail 11 on the floor center side. The mounting rigidity of the seat slide rail 11 is enhanced and the seat 12
It is possible to improve the support stability of.

FIG. 8 shows a second embodiment of the present invention.
A side wall 2a of the floor tunnel 2 is formed with a ledge 2c that bulges laterally, and the end of the upper wall 4a of the third cross member 4 is superposed on the ledge 2c.
A bent portion 7b is formed on the tunnel stay 7 along the lower surface of the shelf 2c, the bent portion 7b is superposed on the lower surface of the shelf 2c, and the upper wall 4 of the shelf 2c and the third cross member 4 is formed.
The seat center slide rail 11 on the floor center side is fastened and fixed by bolts 17 and nuts 16 to the overlapping portion of "a" and the bent portion 7b of the tunnel stay 7.

Therefore, also in this embodiment, since the seat slide rail 11 is fastened and fixed together by the bolts 17 and the nuts 16 at the overlapping portion of the three members, the mounting rigidity of the seat slide rail 11 can be increased and the seat can be improved. 12
It is possible to improve the support stability of.

Further, since the side wall 2a of the floor tunnel 2 is formed by bulging the shelf portion 2c toward the side, when the floor tunnel 2 is deep-drawn during press molding of the floor panel 1, the shelf portion 2c is used. It is possible to use a multi-stage drawing, and it is possible to avoid the formation of wrinkles and cracks in the forming base portion of the floor tunnel 2 due to deep drawing, and it is possible to improve the quality and manufacturing yield.

[0053]

As described above, according to the present invention, the following effects can be obtained.

(1) The left and right third cross members are continuous through the tunnel stay, and further, the left and right third cross members are continuous with the center pillar in the vehicle width direction. The tunnel stay and the center pillar are substantially integrated in the vehicle width direction, so that the function of preventing the opening of the floor tunnel by the tunnel stay and the beam function of the third cross member can be fully exerted. The rigidity can be remarkably increased to reliably prevent drumming due to vibration of the vehicle during traveling, and the quality and reliability can be further improved.

(2) Further, since the center pillar, the left and right third cross members and the tunnel stay are aligned and continuous in the vehicle width direction, the beam function of the third cross member can be sufficiently exerted. At the time of a side collision of the vehicle, the third cross member and the tunnel stay sufficiently oppose the collision load, and the collision load is linearly transmitted not only to the side gill on the other side but also to the center pillar to disperse the load to the body frame member. The load is satisfactorily given, the deformation of the floor panel can be suppressed to a small extent, and a living space in the passenger compartment can be secured, thus improving safety.

(3) By expanding the area of the closed cross section formed by the third cross member and the floor panel with the recessed portion provided in the floor panel, the beam rigidity of the third cross member can be increased and the recessed portion can be formed. Since the surface rigidity of the floor panel is enhanced by the formation of the, it is possible to thoroughly prevent drumming and prevent side collisions.

(4) Since the upper wall of the third cross member is formed to be slanted downward, the rear seat occupants can smoothly put their feet on the upper wall, and the third cross member can be effectively used as a footrest. The third cross member does not become an obstacle, and the habitability around the feet of the rear seat occupant can be significantly improved.

(5) Cross-section of the recess provided in the floor panel
It is formed in a triangular shape, and its top is directed from the floor tunnel side to the side sill side, and is inclined in the rearward oblique direction when seen in a plan view. As a result, the straightening can be performed by deflecting to the side of the floor in the rearward oblique direction, the aerodynamic characteristics of the lower surface of the floor panel can be improved, and the running performance and fuel consumption can be improved.

(6) On the lower surface of the concave portion provided on the floor panel, a receiving portion for the pipes arranged on the lower surface of the floor panel is concavely formed, and a holder portion for holding the pipes accommodated in the receiving portion is formed on the tunnel stay. By doing so, it is possible to arrange the pipes along the lower surface of the floor panel without projecting downward even in the portion where the concave portion is formed, it is possible to avoid the pipes from interfering with the road surface, and the number of clamps for fixing the pipes can be reduced. It is possible to reduce the cost and reduce the cost.

(7) If the connecting position of the tunnel stay to the floor panel is set on the front-rear direction line which is substantially the same as the connecting position of the seat slide rail on the third cross member, the seat slide at the strong tunnel stay connecting position is formed. Since the rail can be attached, the attachment rigidity of the seat slide rail can be increased, and the stability of supporting the seat can be improved.

(8) A side wall bulging ledge is formed on the side wall of the floor tunnel, the upper wall end of the third cross member is superposed on the ledge, and the lower surface of the ledge is attached to the tunnel stay. By forming bent portions that overlap with each other and connecting and mounting the seat slide rails to the overlapped portions of these shelves, the upper wall of the third cross member and the bent portions of the tunnel stay, the seat slide rail can be mounted with rigidity. It is possible to improve the support stability of the sheet.

(9) Further, by forming a ledge that bulges laterally on the side wall of the floor tunnel, when the floor tunnel is deeply drawn during press molding of the floor panel, the ledge is provided with a multi-stage drawing. Therefore, it is possible to avoid the formation of wrinkles and cracks in the molding base of the floor tunnel, and it is possible to improve the quality and manufacturing yield.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

3 is a sectional view taken along the line BB of FIG.

FIG. 4 is a cross-sectional view taken along the line CC of FIG.

FIG. 5 is a plan view of a recess forming portion of the floor panel.

FIG. 6 is an exploded perspective view of the same embodiment.

FIG. 7 is an explanatory cross-sectional view showing a mounted state of the seat slide rail.

FIG. 8 is a sectional view showing a second embodiment of the present invention.

FIG. 9 is a sectional view showing a first example of a conventional structure.

10 is a cross-sectional view taken along the line DD of FIG.

FIG. 11 is a sectional view showing a second example of a conventional structure.

12 is a cross-sectional view taken along the line EE of FIG.

FIG. 13 is a sectional view showing a third example of the conventional structure.

[Explanation of symbols]

1 floor panel 2 floor tunnel 2a Side wall of floor tunnel 3 side sills 3a Silina 4 Third Cross Member 5 center pillars 7 tunnel stay

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography 5-28790 (JP, U) Bibliography 5-54159 (JP, U) Bibliography 57-135452 (JP, U) Bibliography 1- 126884 (JP, U) Actual opening 63-122179 (JP, U) Actual opening 63-114883 (JP, U) Actual opening Flat 3-25382 (JP, U) Actual opening Sho 50-13612 (JP, U) Actually open 1-109486 (JP, U) Actually open 2-148875 (JP, U) Actually open 63-119485 (JP, U) Actually open 59-8941 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B62D 25/20

Claims (5)

(57) [Claims] 1. A third cross member having a substantially U-shaped cross section is joined and arranged in the vehicle width direction on the floor panel with the central floor tunnel in the middle, and across the sill inners of the side sills on both sides of the floor panel and the side walls of the floor tunnel. In the structure, the third cross member is arranged on the same vehicle width direction line as the standing position of the center pillar that is connected to the side sill.
The third cross member arrangement part,
Concave downwards in the vehicle width direction on the member and floor panel.
The floor panel is formed to have a closed cross section with the provided recess and
The concave part of is formed in a triangular shape in cross section, and the top part is viewed in plan.
From the floor tunnel side to the side sill side
A vehicle body floor structure, characterized in that it is formed so as to be inclined, and a tunnel stay is connected to the lower surface of the floor panel across the floor tunnel on the same vehicle width direction line as the third cross member. 2. A third vehicle body floor structure for an automobile according to claim 1, wherein a top wall inclined molded behind edge of the cross member. 3. The lower surface of the recess of the floor panel is provided with a receiving portion for pipes which is recessed upward in the front-rear direction.
Vehicle body floor structure for an automobile according to claim 1, characterized in that it has extended a holder portion for holding the piping accommodated in the receiving portion to the tunnel stay. 4. The tunnel stay stay connecting position with a floor panel is set on substantially the same front-back direction line as a seat slide rail mounting position on a third cross member, according to any one of claims 1 to 3. The car body floor structure described. 5. A shelf portion bulging laterally is formed on a side wall of the floor tunnel, and an upper wall of a third cross member is superposed on and bonded to the shelf portion, while the shelf portion is formed on the tunnel stay. either the lower surface to form a bent portion polymerization of claims 1-4, characterized in that attached to the seat slide rail on the overlapping portion of the top wall and the shelf portion and the bent portion of these third cross member The car body floor structure of the car.