CN100453385C - Vehicle body lower structure - Google Patents

Abstract

The invention provides a vehicle body lower part structure, which prevents or restrains the backward movement of the rear end of a floor frame when a front collision occurs. In the vehicle body lower part structure, a pair of left and right floor frames (10) extending in the front-rear direction and sandwiching a tunnel part (6) are joined to the bottom surface of a front floor part (2). The rear end of the floor frame (10) is located in the vicinity of a rear kick-up portion (3) extending upward from the rear end of the front floor portion (2). The rear end portion and the rear kick-up portion (3) of the floor frame (10) are connected to each other at the vehicle body outer side by end gusset plates (45, 47, 48). The end gusset plates (45, 47, 48) may form a closed cross section together with the rear kick-up portion (3), and may extend outward in the vehicle width direction to be connected to the front end portion of the rear frame (17).

Description

Substructure

technical field

The present invention relates to a vehicle body substructure.

Background technique

Regarding the vehicle body of an automobile, the floor may include a front floor portion having a pair of left and right side beams connected to each other and a channel portion extending in the front-rear direction at the central portion in the vehicle width direction; extending upward from the rear end of the front floor portion. and a rear bottom plate extending substantially linearly rearward from the upper end of the rear upward curve. Generally, a pair of left and right floor frames extending in the front-rear direction and sandwiching the tunnel portion are joined to the bottom surface of the front floor portion, and the side beams and the tunnel portion are joined to connect the side beams and the tunnel portion on the upper surface of the front floor portion. A beam that extends across the width of the vehicle. The above-mentioned floor frame generally has a substantially inverted hat-shaped cross section, and is joined to the front floor section through its left and right flanges.

A pair of left and right front frames are arranged in the front of the base plate, viewed from above, the base frame is located on the rear extension line of the front frame, and is connected to the front end of the base frame with respect to the rear end of the front frame, so that when a frontal collision occurs, the transmission Rearward loads are efficiently transferred from the front frame to the floor frame.

The above-mentioned floor frames are generally arranged to be parallel to the front-rear direction axis of the vehicle body, and extend straight in a straight line, and are arranged to be orthogonal to the above-mentioned beams when viewed from a top view. Patent Document 1 (Japanese Patent Laid-Open Publication No. Hei 11-78959) discloses a structure in which a pair of left and right floor frames gradually incline inward in the vehicle width direction as they extend rearward. Nothing is disclosed about the technical significance of the aforementioned inclination of the floor frame. The technology disclosed in Patent Document 1 is characterized in that the auxiliary frame provided between the pair of left and right front frames is formed into a front-opening, roughly triangular, unique structure in plan view. Considering the shape of the auxiliary frame, Correspondingly, the pair of left and right front frames are also formed into a front-opening type (set to gradually incline outward in the vehicle width direction as it extends forward), so only the floor frame is extended behind the front-opening front frame on-line.

However, when a frontal collision occurs, the collision load input to the pair of left and right front frames and transmitted to the rear is transmitted to the floor frame. The rear end of the floor frame extending to the vicinity of the rear upward bend is usually still open rearward in a substantially inverted hat-shaped cross section, which is a so-called cut-off state. Therefore, in the event of a frontal collision, it is desirable to prevent interference between the rear end of the floor frame when moving backward and various equipment located behind the rear upward curve.

Contents of the invention

The present invention is aimed at solving the above-mentioned problems, and an object of the present invention is to provide a vehicle body substructure capable of preventing or suppressing the backward movement of the rear end of the floor frame in the event of a frontal collision.

In order to achieve the above object, the vehicle body lower structure of the present invention, the floor includes a front floor portion connecting a pair of left and right side beams and having a tunnel portion extending in the front-rear direction at the central part in the vehicle width direction. The rear upper curved portion extending upward, and the rear bottom plate portion extending rearward in a substantially straight line from the upper end of the rear upward curved portion, the bottom surface of the front bottom plate portion is joined with a A pair of left and right floor frames provided at the top of the body, each of the floor frames has a roughly inverted hat-shaped cross section, its front end is joined to the rear end of the left and right pair of front frames, and its rear end extends to the rear upward curve. In the vicinity of the lower part of the vehicle body, the lower structure of the vehicle body is also provided with an end gusset connecting the rear end of the floor frame and the rear upward bend on the outside of the vehicle body. The opening at the rear end of the floor frame can be It is closed by the end gussets.

With the vehicle body lower structure described above, since the rear end portion of the floor frame and the rear upward bend are connected by the end gussets, the rear end of the floor frame can be prevented or restrained from moving backward in the event of a frontal collision. Furthermore, the rigidity of the vehicle body from the rear end of the floor frame to the rear upbend can be improved by the end gussets. In addition, since the rear end of the conventionally cut floor frame is closed by the end gusset, even if it interferes with various equipment located behind the rear upturn, damage can be prevented or reduced.

In the above vehicle body lower structure, the end gussets and the rear upward bend may form a closed section. In this case, the above-described effects can be further sufficiently achieved.

In the above vehicle body lower structure, the end gusset may have a forward protruding portion having a substantially inverted hat-shaped cross section, and the forward protruding portion may be engaged with a rear end portion of the floor frame. At this time, since the front protrusion having the same cross-sectional shape as the floor frame is formed on the end gusset, the rear end of the floor frame and the end gusset can be joined easily and reliably.

In the above vehicle body lower structure, the front floor portion may be joined with a beam extending in the vehicle width direction and connecting the side sill and the tunnel portion, and the front protruding portion of the end gusset may extend to the The front protruding portion constitutes a portion of the floor frame that is located behind the specific cross beam in the specific cross beam that is closest to the rear upward curved portion. In this case, the rear end portion of the floor frame is substantially constituted by the front protruding portion of the end gusset plate. Accordingly, the length of the floor frame, which is a long member joined to the front floor portion, can be shortened as much as possible, and the handling and joining work of the floor frame can be simplified. In addition, the connecting portion of the floor frame and the end gusset, which is easy to form a complex structure, is formed in advance on the end gusset, so that the connecting portion of the floor frame and the end gusset can be reinforced, and the connecting portion can be Machined into desired shape.

In the vehicle body lower structure described above, the floor frame may be formed of a high-tensile steel plate from its front end to a portion joined with the front protrusion of the end gusset, having the end corner of the front protrusion. The struts may be formed from ordinary steel plates. At this time, the front part of the floor frame that needs to transmit a large impact load in the event of a frontal collision is made of a high-tensile steel plate, so that buckling of this part can be prevented, and the rear part of the floor frame is formed of a normal steel plate. This reduces costs.

In the vehicle body lower structure described above, the outer end portion of the end gusset in the vehicle width direction may be connected to the front end portion of the rear frame joined to the bottom surface of the rear floor portion, and the vehicle width of the end gusset may be connected to the front end portion of the rear frame. The widthwise inner end portion may extend to a base end of the channel portion. In this case, it is preferable to increase the strength of the vehicle body in the vehicle width direction, and it is particularly preferable to prevent the passage portion from being separated.

In the vehicle body lower structure described above, a rear cross member connecting front ends of a pair of left and right rear frames to which the bottom surface of the rear floor portion is joined is provided, and the rear end portion of the floor frame is opposite to the rear cross member. Joined, the rear cross member constitutes the end gusset. In this case, the strength (rigidity) of the vehicle body can be greatly improved by the rear cross member, and the rear cross member can also be used as an end gusset.

In the above vehicle body lower structure, the rear cross member may form a closed section together with the front end portion of the rear floor portion, the rear upward curve, and the rear end portion of the front floor portion. In this case, the above-described effects can be further sufficiently achieved.

In the vehicle body lower structure described above, a fuel tank may be provided behind the rear upward curve and below the rear floor, and the fuel tank may be installed on the vehicle body at the front and rear positions of the fuel tank. A holding belt extending in the front-rear direction is held from below, and the end gusset may be provided with a front belt mounting portion to which a front end portion of the holding belt is mounted. In this case, the rearward extension member of the floor frame as a vehicle body strength member, i.e., the end gusset, can also be used as a bracket on which the front belt mounting portion is formed, so there is no need to separately provide a dedicated front belt mounting portion. bracket. Moreover, the floor frame has a strong resistance to the tensile force in the front and rear directions, and on the other hand, the front belt mounting part is subjected to a large rearward tensile force due to the weight of the fuel tank, so the floor frame can fully resist The larger rearward tensile force experienced by the above-mentioned retaining strap. In addition, the rigidity of the vehicle body in the vicinity of the rear upper bend can also be improved by the above-mentioned end gussets.

In the above vehicle body lower structure, a pair of left and right rear frames extending in the front-rear direction are joined to the bottom surface of the rear floor portion on the outside of the fuel tank in the vehicle width direction, and on the pair of left and right rear frames, A connecting beam connecting the respective rear frames is provided at a position behind the fuel tank, and the connecting beam is provided with a rear belt attachment portion to which a rear end portion of the holding belt is attached. At this time, the rear belt attachment portion may be formed using a connecting beam as a strength member.

In the vehicle body lower structure described above, the front belt mounting parts are provided in a pair of left and right corresponding to the floor frames, and the rear belt mounting parts formed in the connecting beam are in a pair of left and right. , corresponding to each of the belt mounting parts, a first holding belt and a second holding belt are provided, and the first holding belt is installed on the front belt mounting part on the right side and the rear belt on the left side Between the two mounting parts, the second holding belt is installed between the front belt mounting part on the left side and the rear belt mounting part on the right side, and the first holding belt and The second holding belts cross each other below the fuel tank. At this time, the fuel tank can be stably and securely held by the two sets of holding belts arranged in a cross pattern.

In the vehicle body lower structure described above, the front belt mounting parts are provided as a left and right pair corresponding to each of the floor frames, and the rear belt mounting parts formed on the connecting cross member are provided as a left and right pair. The belts are provided with a first holding belt and a second holding belt corresponding to the belt installation parts, and the first holding belt is installed on the front belt installation part on the right side and the rear belt installation part on the right side. Between the two strap mounting parts, the second holding strap is mounted between the front strap mounting part on the left side and the rear strap mounting part on the left side, and the first holding strap The second holding belt is arranged side by side at regular intervals in the vehicle width direction. At this time, the fuel tank can be stably and securely held by the two sets of holding belts arranged side by side.

In the above vehicle body lower structure, the upper surface of the front floor portion may be joined with a cross member extending in the vehicle width direction and connecting the side beams and the tunnel portion, and the floor frame may extend toward the vehicle width as it extends rearward. The direction is inclined inwardly, and it is inclined relative to the beam in plan view, and the flange part of the floor frame and the flange part of the beam are joined in a three-piece overlapping state with the front floor part sandwiched between them. , the left and right pair of front frames extend parallel to each other along the front-rear direction, and the distance between the rear ends of the left and right pair of front frames is set to be approximately the same as the distance between the front ends of the left and right pair of floor frames. At this time, since the distance between the rear ends of the pair of left and right floor frames is smaller than in the conventional structure, it is extremely suitable as the formation position of the front belt attachment portion. In addition, the crossbeam withstands the floor frame that needs to retreat in the event of a frontal collision through strong compression and stretching of the material mechanics, so that not only the above-mentioned end gussets but also the crossbeam can further effectively withstand the impact caused by the frontal collision. generated load. In addition, the floor frame and the beam are joined together in a state where the flange portions and the front floor portion of both are overlapped, so that the above-mentioned collision load can be reliably transmitted from the floor frame to the beam. In addition, since the floor frame is inclined, its overall length can be longer than that of a structure that is parallel and straight to the front-rear axis of the vehicle body, thereby improving the impact absorption of the floor frame itself. In addition, the pair of left and right floor frames are generally arranged in parallel, so the support of the engine (power train) by the floor frame can be exactly the same as conventional structures.

To sum up, according to the present invention, in the event of a frontal collision, the backward movement of the rear end of the floor frame can be prevented or suppressed, and the rigidity of the vehicle body can also be improved.

Description of drawings

FIG. 1 is a plan view showing an embodiment of the present invention.

Fig. 2 is a sectional view taken along line 2-2 in Fig. 1 .

Fig. 3 is a perspective view showing the arrangement relationship of strength members such as a floor frame, a cross beam, a side beam, and a rear frame in Fig. 1 .

Fig. 4 is a perspective view showing a connection state of a floor frame, a front frame, and side members.

FIG. 5 shows the joint relationship between the floor frame, the beam, and the front floor portion, and is a cross-sectional view taken along line 5-5 in FIG. 6 .

Fig. 6 is a schematic view of the intersection of the floor frame and the beam viewed from above.

Fig. 7 is a perspective view of the intersection of the floor frame and the beam viewed from below, and the illustration of the front floor portion is omitted.

Fig. 8 is a perspective view showing an example of main parts of an end gusset.

Fig. 9 is a side sectional view showing an example of a preferred vehicle body assembly in the vicinity of the end gusset shown in Fig. 8 .

Fig. 10 is a side sectional view showing an example of a preferred vehicle body assembly in the vicinity of the end gussets shown in Fig. 8 .

Fig. 11 is a side sectional view showing an example of a preferred vehicle body assembly in the vicinity of the end gussets shown in Fig. 8 .

Fig. 12 shows a second embodiment of the present invention, and shows a perspective view of an example of a fourth cross member as a rear cross member.

Fig. 13 is a side sectional view showing the relationship between the fourth beam shown in Fig. 12 and the rear upward curve.

Fig. 14 is a perspective view showing a connecting portion between the fourth beam shown in Fig. 12 and the rear end of the floor frame.

Fig. 15 is a sectional view taken along line 15-15 in Fig. 14 .

Fig. 16 is a side sectional view showing main parts of a third embodiment of the present invention.

Fig. 17 shows a fourth embodiment of the present invention, and is a bottom view of main parts in the vicinity of the rear upward curve viewed from below.

FIG. 18 is a perspective view of the end gusset shown in FIG. 17 .

Fig. 19 is a perspective view of a part corresponding to Fig. 17 .

Fig. 20 is a sectional view taken along line 20-20 in Fig. 19 .

Fig. 21 shows a fifth embodiment of the present invention, and is a bottom view of main parts corresponding to Fig. 17 .

Fig. 22 shows the retaining belt, and is a perspective view of main parts of the fuel tank portion.

Fig. 23 is a side sectional view of main parts showing a state in which the fuel tank is held by the holding belt.

Figure 24 is a perspective view showing a preferred bracket for the intersection of two holding straps.

Fig. 25 is a side sectional view of main parts of the end gusset portion shown in Fig. 8 .

FIG. 26 shows another embodiment of the holding belt installation structure, which is a bottom perspective view corresponding to FIG. 22 .

Detailed ways

In Fig. 1 and Fig. 2, 1 is a bottom plate, which is formed by joining together a plurality of plates formed by dividing along the front-rear direction. The bottom plate 1 generally includes a front bottom plate portion 2, a rear upward curved portion 3 that rises shortly upward from the rear end of the front bottom plate portion 2, and a rear bottom plate portion 4 that extends rearward from the upper end of the rear upward curved portion 3. . The front end of the front floor portion 2 extends in the vertical direction, and is connected to the lower end of a partition 5 that partitions the vehicle compartment and the engine compartment.

The front floor part 2 is formed with a channel part 6 extending in the front-rear direction at the central part in the vehicle width direction. connected (opening to the rear). The left and right end portions of the front floor portion 2 are joined to a pair of left and right side beams 7 as strength members extending in the front-rear direction.

A fuel tank 8 is provided directly behind the rear upward curve 3 and directly below the rear floor 4 . At the rear position of the fuel tank 8 , that is, on the rear floor portion 4 , a housing portion 9 protruding downward is formed, and a spare tire and the like can be accommodated in the housing portion 9 .

In FIGS. 1 to 3 , a pair of left and right floor frames 10 are joined to the bottom surface of the front floor portion 2 , and the channel portion 6 is located between the pair of left and right floor frames 10 . That is, each floor frame 10 is located between the tunnel portion 6 and the side member 7 in the vehicle width direction. The floor frame 10 extends linearly in the front-rear direction as a whole, but is inclined with respect to the vehicle body front-rear direction axis. That is to say, the left and right pair of floor frames 10 are respectively inclined gradually inward in the vehicle width direction (closer to the tunnel portion 6 ) as they extend toward the rear, and the distance between the front end and the vehicle width direction is set to be greater than that of the rear end. The distance between the ends in the width direction of the vehicle. In addition, the inclination angles of the pair of left and right floor frames 10 are equal. The cross-sectional shape of the floor frame 10 is formed in an inverted hat shape opened upward as described below, and a closed cross section is formed by being joined to the front floor portion 2 . In addition, the rear end of the floor frame 10 is connected to the rear upward bend 3 through an end gusset 45 described later, and the opening at the rear is closed by the end gusset 45. The end gusset in FIG. 3 45 is omitted.

Also as shown in FIG. 4 , the front ends of the pair of left and right floor frames 10 are directly joined and connected to the rear ends of the pair of left and right front frames 11 . That is, the pair of left and right front frames 11 are parallel to each other, and also parallel to the axis of the front and rear direction of the vehicle body (not inclined in plan view), the distance between the rear ends of the pair of left and right front frames 11 in the vehicle width direction is , which is substantially the same as the distance between the front ends of the pair of left and right floor frames 10 in the vehicle width direction. In addition, since the installation method of the front frame 11 is the same as the conventional one, the same structure as the conventional one can be used by utilizing the support of the engine (power train) by the front frame 11 .

The rear end of the front frame 11 is positioned more rearward than the front end of the side sill 7, and the rear end of the front frame 11, the front end of the side sill 7, and the front end of the floor frame 10 use a torsion box as a strength member. 12 (torque boxes) are connected to each other.

Two sets of front and rear beams 15 and 16 are joined to the upper surface of the front floor portion 2 . That is, the first beam 15 located on the front side is provided at approximately the middle position in the front-rear direction of the front floor portion 2, and the second beam 16 located at the rear side is provided approximately at the middle position between the first beam 15 and the rear upward curved portion 3. Location. Each beam 15 , 16 is divided into two members in the vehicle width direction at the tunnel portion 6 , and each beam 15 , 16 connects the inner surface of the side member 7 and the outer surface of the tunnel portion 6 . The cross-sections of the beams 15 , 16 are substantially hat-shaped opening downward, and are joined to the front floor portion 2 to form a closed cross-section. The beams 15 , 16 extend perpendicularly to the front-rear axis of the vehicle body, as in the conventional case, and are arranged obliquely relative to the floor frame 10 in plan view.

A pair of left and right rear frames 17 extending in the front-rear direction are joined to the bottom surface of the rear floor portion 4 . The front end of the rear frame 17 is joined to the rear end of the side member 7 . The left and right pair of rear frames 17 are connected between the fuel tank 8 and the housing portion 9 by a third beam 18 extending in the vehicle width direction. The cross-sectional shape of the rear frame 17 is an inverted hat shape opening upward, and is joined to the rear floor portion 4 to form a closed cross-section.

Next, referring to FIGS. 5 to 7 , the joining relationship between the beams 15 , 16 and the floor frame 10 with respect to the front floor portion 2 will be described in detail. First, the floor frame 10, as shown in FIGS. 5 and 7, has a pair of left and right side wall portions 10a, a bottom wall portion 10b connecting the lower ends of the left and right pair of side wall portions 10a, and a bottom wall portion 10b extending from the left and right pair of side walls. The upper end of the portion 10a is a pair of left and right flange portions 10c extending approximately horizontally. The floor frame 10 is joined (welded in the embodiment) to the front floor portion 2 in a state where each flange portion 10c is in contact with the bottom surface of the front floor portion 2 (the front floor portion 2 is not shown in FIG. 7 ). .

The joining methods of the beams 15 and 16 to the front floor portion 2 and the floor frame 10 are the same, and the first beam 15 will be described here. First, the first beam 15 has a pair of front and rear side wall portions 15a, an upper wall portion 15b connecting the upper ends of the front and rear pair of side wall portions 15a, and a substantially horizontally extending bottom end of the front and rear pair of side wall portions 15a. A pair of front and rear flange portions 15c. The first beam 15 is joined (welded in the embodiment) to the front floor portion 2 in a state where each flange portion 15c is in contact with the upper surface of the front floor portion 2 (the front floor portion 2 is omitted in FIG. 7 ). Show).

1, 6, and 7, the left and right flanges 10c of the floor frame 10 and the front and rear flanges 15c of the crossbeam 15 (the same for the crossbeam 16) have a total of four crossings in plan. The crossing portions are joined to each other, and the joining portion is indicated by a symbol α in FIGS. 5 and 6 . That is, in particular, as can be seen from FIG. 5 , in a state where the front floor portion 2 is sandwiched between the flange portion 10c of the floor frame 10 and the flange portion 15c of the beam 15 (16), the respective flange portions 10c and 15c are connected to the front. The bottom plate portion 2 is joined to each other in a state where three are overlapped (welded joint in the embodiment).

Next, referring to FIGS. 8 to 11 , the parts related to the end gusset 45 will be described (the end gusset 45 is also briefly shown in FIGS. 1 and 2 ). First of all, the end gussets are usually stamped and formed from ordinary steel plates to form the shape shown in Figure 8. That is, the end gusset 45 has a front protruding portion 45A corresponding to the cross-sectional shape of the floor frame 10 and having a substantially inverted hat-shaped cross-section. Furthermore, the end gusset 45 has a bottom wall portion 45a (also constituting the bottom wall of the forward protruding portion 45A), a rear wall portion 45b extending upward from the rear end of the bottom wall portion 45a, and left and right sides of the bottom wall portion 45a. A pair of left and right side wall parts 45c whose side ends are connected to the left and right side ends of the rear wall part 45b are formed into a box shape by the above-mentioned wall parts. That is, the end gusset 45, as described below, is closed (downward, rearward) except for the opening facing the bottom surface of the front floor portion 2 and the opening facing the rear of the rear upward bend 3 in the state of being attached to the vehicle body as described below. , and the left and right sides are closed). Furthermore, the end gusset plate 45 is further formed with a joining flange portion 45d which is connected to the flange portion 10c of the floor frame 10 .

The above-mentioned end gusset 45 is joined to the bottom surface of the rear end of the front floor portion 2 and the rear surface of the rear upward curve 3 by its flange portion 45d, as shown particularly in FIG. 8 . In this joined state, a closed section is formed together with the rear end portion of the front bottom plate portion 2 and the rear upward curve portion 3 . The rear end of the floor frame 10 is connected to the rear upward bend 3 through the end gusset 45 , and in this joined state, the rear opening of the floor frame 10 is closed by the end gusset 45 .

9 to 11 show the preferred assembly process around the rear upward bend 3 including the end gusset 45. In this embodiment, the position slightly forward relative to the rear end of the front floor 2 is taken as the boundary, The base plate 1 is divided into a front panel 1A and a rear panel 1B, and these are joined to each other at the boundary portion.

First, as shown in Figure 9, the bottom surface of the front panel 1A is joined with the base frame 10 (the flange portion 10c) (joint is indicated by symbol α), at this time, the rear end of the base frame 10 is slightly behind the front panel 1A The state that protrudes backward. Next, as shown in FIG. 10 , the front protruding portion 45A of the end gusset 45 is joined to the upper surface of the rear end portion of the floor frame 10 . Finally, the front end portion of the rear end portion 1B is joined to the rear end portion of the front end portion 1A, while the upper end portion of the end gusset 45 is joined to the rear face of the rear panel 1B (in the rear upward bend 3B). In addition, a working hole 10f for inserting a welding gun used for joining the front and rear panels 1A and 1B is formed on the bottom surface of the rear end portion of the floor frame 10 .

In the above structure, the impact load generated when a frontal collision occurs is firstly input into the front frame 11 , then transmitted from the front frame 11 to the floor frame 10 , and also transmitted to the side beam 7 through the torsion box 12 . The floor frame 10 to which a collision load is input absorbs the impact by the floor frame 10 itself and the front floor portion 2 joined thereto. At the same time, the floor frame 10 displaced rearward by the impact load also transmits the impact load to the beams 15 and 16 , so that the impact can be absorbed by the beams 15 and 16 as described below. In addition, since the floor frame 10 is installed at an inclination, the overall length can be increased compared with a structure not inclined (a structure arranged parallel to the axis of the front and rear direction of the vehicle body). Absorption of impact by the front floor portion 2 joined by the frame 10 can be performed more effectively.

Since the floor frame 10 is inclined relative to the cross beams 15, 16, the impact load from the floor frame 10 to the cross beams 15, 16 can be transmitted from a direction inclined relative to the vehicle width direction axis of the cross beams 15, 16. That is, among the beams 15 , 16 , a compressive force acts on a portion on the side beam 7 side relative to the floor frame 10 , and a tensile force acts on a portion on the tunnel portion 6 side relative to the floor frame 10 . Since the beams 15 and 16 have a large resistance against compressive force or tensile force, they can more effectively withstand the impact load transmitted rearward than conventional cases where only bending force or shearing force acts on them.

Among the two sets of front and rear beams 15 , 16 , the impact load transmitted from the floor frame 10 to the rear is larger for the first beam 15 located in the front than for the second beam 16 located in the rear. That is, since the rearwardly transmitted impact load transmitted to the rearward second beam 16 is relatively small, large rearward displacement of the rear end of the floor frame 10 can be prevented or suppressed. In addition, since the rear end of the floor frame 10 is connected to the rear upward bend 3 through the end gusset 45, the rearward movement of the rear end of the floor frame 10 can be more reliably prevented or suppressed. That is, it is possible to prevent the rear end of the floor frame 10 from interfering with the fuel tank 8 and the like provided behind the rear upward curve 3 . Of course, the rigidity near the lower end of the rear upward bend 3 can be improved by the end gusset 45 itself. Since the rear upward curved portion 3 can generally constitute the bottom surface of the rear seat, the rigidity of the vehicle body near the rear seat can be further improved.

12 to 15 show the second embodiment of the present invention, and the same components as those of the above-mentioned embodiment are denoted by the same reference numerals, and their repeated descriptions are omitted (this is also the same for other embodiments below). In the present embodiment, the fourth beam 41 is provided separately, and the fourth beam 41 functions as an end gusset. That is, the front ends of the pair of left and right rear frames 17 can be connected by the fourth beam 41 extending in the vehicle width direction as shown in FIG. 12 . The fourth beam 41 is connected to the rear ends of the floor frames 10 .

The 4th beam 41 forms the shape shown in FIG. The bottom surface of the rear floor portion 4 is joined to the bottom surface of the front end of the rear floor portion 4 by means of the flange portion 41e at its upper end. The fourth beam 41 constitutes a closed section together with the rear end portion of the front floor portion 2 , the rear upward curve portion 3 , and the front end portion of the rear floor portion 4 .

The rear end opening of the floor frame 10 is covered by the front wall portion of the fourth beam 41 . The rigidity of the vehicle body can be greatly improved by the fourth cross member 41, and the increase in the number of parts can be avoided as much as possible while realizing the function of the end gusset plate 45 in the above-mentioned embodiment. In addition, the front protrusion 45A of the end gusset 45 in the above embodiment may be formed on the fourth beam 41 (a pair of left and right front protrusions may be formed).

FIG. 16 shows a third embodiment of the present invention, and shows a structure in which the end gusset 45 shown in FIG. 8 and the fourth beam 41 shown in FIG. 12 are provided together. Fig. 16 is a sectional view corresponding to Fig. 11 and Fig. 13. By arranging the above-mentioned members 41 and 45, the backward movement of the rear end of the floor frame 10 can be further prevented or suppressed, and the rigidity of the vehicle body can be further improved.

17 to 20 show a fourth embodiment of the present invention. In this embodiment, the end gusset 47 has the shape shown in FIG. 18 . That is, the end gusset 47 ′ has a front protruding portion 47A having the same cross-sectional shape as the floor frame 10 . In addition, the end gusset 47 extends longer in the vehicle width direction than the end gusset 45 shown in FIG. 8 . That is, the vehicle width direction outer end of the end gusset 47 is joined to the front end of the rear frame 17 , and the vehicle width direction inner end is joined to the tunnel portion 6 (the base end that starts to rise upward). In addition, (the inner plate of) the side beam 7 is formed with 7 f of working holes used when the frame 17 and the end gusset 47 are welded (see FIG. 20 ).

The end gusset 47 has a bottom wall portion continuously extending from the bottom wall portion of the front protruding portion 47A, and has approximately the same height as the bottom surface of the floor frame 10, and the front end (upper end) of the rear wall portion 47b is directed upward. It extends longer and joins with the back of the rear upward curve 3 to form a closed section together with the rear upward curve B3.

FIG. 21 shows a fifth embodiment of the present invention, which is a modified example of the end gusset 47 shown in FIGS. 17 to 20 . That is, the end gusset 48 in this embodiment is substantially the same as the end gusset 47 of the above-mentioned embodiment, and the front protrusion 48A (the part corresponding to 47A) is set to be long, and the front protrusion 48A The front end extends to the vicinity of the second beam 16. That is, the front protruding portion 48A substantially constitutes the rear end portion of the floor frame 10 extending to the vicinity of the rear upward curve 3 . The front side portion of the floor frame 10 (the lengthwise portion from the front end to the second beam 16 ) is formed of a high-tensile steel plate, and the end gusset 48 is formed of an ordinary steel plate. In this embodiment, since the floor frame 10 is made of high-strength steel plates and ordinary steel plates, there is no need to prepare separate dedicated members, and the rear side part of the floor frame 10 formed by using ordinary steel plates can constitute a part of the end gusset plate 48. (Front protrusion 48A).

Next, referring to FIGS. 22 to 24 , the mounting structure of the holding belt for holding the fuel tank 8 from below will be described. In this embodiment, the base plate 1 is divided into a front panel 1A and a rear panel 1B at a position slightly forward with respect to the rear end of the front base plate portion 2, and joined to each other at the boundary portion.

First, as the holding belts, two sets of the first holding belt 51 and the second holding belt 52 can be used. In addition, nuts 53 serving as front belt attachments are joined in advance to rear end portions (bottom wall portions) of each floor frame 10 (forming a pair of left and right front belt attachments). In addition, a pair of left and right nuts 54 serving as rear belt attachment portions are joined in advance to the bottom wall portion of the third beam (connecting beam) 18 located behind the fuel tank 8 . The position of the rear nut 54 in the vehicle width direction can be set on a substantially rearward extension of the front nut 53 . Of course, bolt penetration holes corresponding to the nuts 53 or 54 may be formed in the floor frame 10 and the third beam 18 .

Attachment of the front ends of the respective holding bands 51 and 52 to the floor frame 10 can be performed by bolts 55 screwed into the nuts 53 from below. In addition, the attachment of the rear end portion of each of the holding belts 51 and 52 to the third beam 18 can be performed by a bolt 56 screwed into the above-mentioned nut 54 from below. In this embodiment, two sets of holding belts 51 and 52 are provided in a crossed state. That is, the first holding band 51 has its front end fixed to the left nut 53 side and its rear end fixed to the right nut 54 side. On the contrary, the second holding band 52 has its front end fixed to the right nut 53 side and its rear end fixed to the left nut 54 side. As a result, the two sets of holding belts 51 and 52 cross each other below the fuel tank 8 . The left and right nuts 53 located on the front side, that is, the positions of the rear ends of the pair of left and right floor frames 10 in the vehicle width direction, compared with the structure in which the floor frames 10 are arranged parallel to the axis of the front-rear direction of the vehicle body and are in a non-inclined state, The fuel tank 8 can be held in a highly balanced manner by moving inward in the vehicle width direction. Especially, when the length of the fuel tank 8 in the vehicle width direction is short, the holding of the fuel tank 8 is very effective.

The cross position of the two sets of holding belts 51 and 52 can be provided with a bracket 57 as shown in FIG. 24 . The bracket 57 is substantially X-shaped as a whole, and the height of its side wall is equal to or greater than the thickness of the overlapping of the two holding belts 51 and 52 . By means of the bracket 57, it is possible to reliably maintain the crossing state of the two holding belts 51 and 52 at a predetermined angle. In addition, the bracket 57 may be fixed to the bottom surface of the fuel tank 8 by bonding or the like, or may be fixed to at least one of the holding belts 51 and 52 by bonding or the like.

What Fig. 25 has shown is another embodiment of the installation structure of retaining belt 51, 52, utilizes above-mentioned end gusset plate 45 (referring to Fig. 8) to connect the rear end portion of floor frame 10 with rear upper curved portion 3, and here Front belt mounts for holding belts are formed on the end gussets 45 . First, the end gussets 45 are made of ordinary steel plates through press forming to form the shape shown in FIG. 11 . That is, the end gusset 45 has a front protruding portion 45A corresponding to the cross-sectional shape of the floor frame 10 and having a substantially inverted hat-shaped cross-section. Furthermore, the end gusset 45 has a bottom wall portion 45a (also constituting the bottom wall of the forward protruding portion 45A), a rear wall portion 45b extending upward from the rear end of the bottom wall portion 45a, and a gap between the bottom wall portion 45a and the bottom wall portion 45a. A pair of left and right side wall parts 45c whose left and right side ends are connected to the left and right side ends of the rear wall part 45b are formed into a box shape by the above-mentioned wall parts. That is, as described below, the end gusset 45 is closed except for the opening facing the bottom surface of the front floor portion 2 and the opening facing the rear of the rear upturned portion 3 in the state of being attached to the vehicle body (downward, downward). The rear, as well as the left and right sides are closed). Furthermore, the end gusset plate 45 is further formed with a joining flange portion 45d which is connected to the flange portion 10c of the floor frame 10 .

The above-mentioned end gusset 45 is joined to the bottom surface of the rear end of the front bottom plate 2 and the rear surface of the rear upward curve 3 by its flange portion 45d, as shown particularly in FIG. 25 . In this joined state, a closed section is formed together with the rear end portion of the front bottom plate portion 2 and the rear upward curve portion 3 . The rear end of the floor frame 10 is connected to the rear upward bend 3 through the end gusset 45 , and in this connected state, the rear opening of the floor frame 10 is closed by the end gusset 45 . In addition, the nut 53 shown in FIG. 25 is omitted from illustration in FIG. 8 .

FIG. 26 shows another embodiment of the attachment structure of the holding belts 51 and 52 . In the present embodiment, the two holding belts 51 and 52 are arranged side by side with each other, that is, they have a structure arranged in parallel. That is, the front end and the rear end of the first holding band 51 can be fixed by the nuts 53 and 54 located on the left side, respectively. In addition, the front end and the rear end of the second holding band 52 can be fixed by the nuts 53 and 54 located on the right side, respectively.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and can be appropriately modified within the scope described in the claims, and may include, for example, the following configurations. The floor frame 10 can be made of the same material over its entire length (for example, high-tensile steel is used over its entire length). Viewed from above, the cross beams intersecting the floor frame 10 may not be limited to 2 groups, and may also be 1 group or 3 groups or more. The beams 15 and 16 may be provided on the bottom surface of the front floor portion 2 . A pair of left and right floor frames 10 may be arranged parallel to each other (parallel to the front-rear axis of the vehicle body). The end gusset 45 is also used as a mounting portion for holding (the front end portion of) the holding belt that supports the fuel tank 8 from below. At this time, a fixing tool such as a nut for fastening the holding band is integrally formed with the end gusset plate 45 by pre-welding or the like. In particular, when the left and right pair of floor frames 10 are gradually inclined toward the inside in the vehicle width direction as they extend toward the rear, the position of the end gussets 45 in the vehicle width direction can be very close to the tunnel portion 6, so that they can be installed in the vehicle width direction. Tightening maintains the preferred position of the front end of the strap. As the belt mounting portion, screw holes for bolts may be directly formed at the rear end portion of the floor frame 10 instead of the nuts 53 and 54, so that an appropriate member can be selected from other fixing members. On the bottom surface of the fuel tank 8, shallow grooves in which the holding belts 51 and 52 are fitted may be formed. Of course, the purpose of the present invention is not limited to the contents of the express description, but also includes other ideal or advantageous structures in essence.

Claims (13)

1. A car body substructure, characterized in that: It has a floor plate including a front floor portion connecting a pair of left and right side beams and having a tunnel portion extending in the front-rear direction at a central portion in the vehicle width direction, and a rear upward curved portion extending upward from the rear end of the front floor portion, and a rear bottom plate extending substantially linearly rearward from the upper end of the rear upward curve, A pair of left and right floor frames extending in the front-rear direction and sandwiching the tunnel portion are bonded to the bottom surface of the front floor portion, Each of the floor frames has a substantially inverted hat-shaped cross section, and its front end is joined to the rear end of a pair of left and right front frames, and its rear end extends to the vicinity of the rear upward bend, The vehicle body lower structure is provided with an end gusset plate connecting the rear end of the floor frame and the rear upward bend on the outside of the vehicle body, The opening at the rear end of the floor frame is closed by the end gusset. 2. The vehicle body substructure according to claim 1, wherein: The end gusset together with the rear upward bend forms a closed section. 3. The vehicle body substructure according to claim 2, wherein: The end gusset has a front protruding portion protruding forward and having a substantially inverted hat-shaped cross section, The front protrusion is engaged with the rear end of the floor frame. 4. The vehicle body substructure according to claim 3, wherein: The front floor part is joined with a cross member extending in the vehicle width direction and connecting the side member and the tunnel part, The front protruding portion of the end gusset plate extends to a specific beam located at a position closest to the rear upturned portion among the beams, and the front protruding portion constitutes a rear portion of the specific beam in the floor frame. part. 5. The vehicle body substructure according to claim 4, wherein: The floor frame, wherein the portion from its front end to the portion joined with the front protrusion of the end gusset plate is formed of a high-tensile steel plate, The end gussets having the forward protrusions are formed of ordinary steel plates. 6. The vehicle body substructure according to claim 3, wherein: The vehicle width direction outer end portion of the end gusset is connected to the front end portion of the rear frame joined to the bottom surface of the rear floor portion, An inner end portion of the end gusset in the vehicle width direction extends to a base end of the tunnel portion. 7. The vehicle body substructure according to claim 1 or 2, characterized in that, a rear cross member connecting front ends of a pair of left and right rear frames to which the bottom surface of the rear floor portion is joined is provided, the rear end of the floor frame is joined relative to the rear cross member, The rear cross member constitutes the end gusset. 8. The vehicle body substructure according to claim 7, wherein: The rear cross member forms a closed section together with the front end of the rear floor, the rear upward curve, and the rear end of the front floor. 9. The vehicle body substructure according to claim 1, wherein: A fuel tank is arranged behind the rear upward curve and below the rear bottom plate, The above-mentioned fuel tank is held from below by holding belts that are attached to the vehicle body at the front and rear positions of the fuel tank and extend in the front-rear direction, The end gusset is provided with a front belt attachment portion to which the front end of the holding belt is attached. 10. The vehicle body substructure according to claim 9, wherein: A pair of left and right rear frames extending in the front-rear direction are joined to the bottom surface of the rear floor portion on the outside of the fuel tank in the vehicle width direction, On the pair of left and right rear frames, at a position behind the fuel tank, there is provided a connecting beam connecting the respective rear frames, The connecting beam is provided with a rear belt mounting portion to which a rear end portion of the holding belt is mounted. 11. The vehicle body substructure according to claim 10, wherein: The front belt installation part is arranged in a pair of left and right corresponding to each of the floor frames, The rear belt mounting part formed on the connecting beam is a pair of left and right, The holding belt is provided with a first holding belt and a second holding belt corresponding to the belt mounting parts, The first holding belt is mounted between the front belt mounting portion on the right side and the rear belt mounting portion on the left side, The second holding belt is mounted between the front belt mounting part on the left side and the rear belt mounting part on the right side, The first holding band and the second holding band intersect each other below the fuel tank. 12. The vehicle body substructure according to claim 10, wherein: The front belt mounting parts are arranged in a pair of left and right corresponding to each of the floor frames, The rear belt mounting part formed on the connecting beam is a pair of left and right, The holding belt is provided with a first holding belt and a second holding belt corresponding to the belt mounting parts, The first holding belt is mounted between the front belt mounting portion on the right side and the rear belt mounting portion on the right side, The second holding belt is mounted between the left front belt mounting part and the left rear belt mounting part, The first holding belt and the second holding belt are arranged side by side at regular intervals in the vehicle width direction. 13. The vehicle body substructure according to claim 10, wherein: A cross member extending in the vehicle width direction and connecting the side member and the tunnel portion is joined to the upper surface of the front floor portion, The floor frame is inclined inwardly in the vehicle width direction as it extends rearward, and is inclined relative to the beam in plan view, The flange portion of the floor frame and the flange portion of the beam are joined in a three-piece overlapping state with the front floor portion interposed therebetween, The pair of left and right front frames extend parallel to each other along the front and rear directions, The distance between the rear ends of the pair of left and right front frames is set to be substantially the same as the distance between the front ends of the pair of left and right floor frames.

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