JP2000072030A - Automobile floor reinforcing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide automobile floor reinforcing structure that can increase absorbing energy of a body consequent to deformation by eliminating local deformation, and providing rigidity with the whole body. SOLUTION: A side sill 3, a cross member 2, a torque box 10 and a rear (seat) cross member 6 have strength enough to function as structural members in charge of the rigidity of deformation to load from the body side face, and extension members 11 are arranged to reach the rear (seat) cross member 6 from the rear end of the front side member 5 via a joint part of the cross member 2 to a floor tunnel 8, and rigidity jointed to a front floor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile body structure for reinforcing an automobile side sill, a cross member and a front floor, and more particularly to an automobile floor reinforcement structure capable of coping with a side collision.

[0002]

2. Description of the Related Art As a conventional reinforcing structure for a side sill, a cross member and a front floor of an automobile, there is a structure as shown in FIG. 7. As a conventional reinforcing structure, for example, Japanese Patent Application Laid-Open No. Hei 5-116647 is disclosed. Kaihei 5-124
542, JP-A-5-201353, JP-A-5-270435, JP-A-6-32254, and JP-A-7-137660.

[0003]

However, in such a conventional vehicle side sill, cross member, and front floor reinforcing structure, and a vehicle floor reinforcing structure in which these are combined in a complex manner, a collision from a side surface is required. When generating and transmitting the load associated with the collision with an object, it simply reinforces the rigidity and strength against twisting caused by the bending of the side sill at the bottom of the vehicle body and the rotation of the cross section. The load that is transmitted as if by reinforcing the rigidity and strength to resist out-of-plane deformation, and by further reinforcing the high stress distribution area to suppress local deformation, that is, to suppress local deformation. The design policy has been determined based on the evaluation as if the number of Not be fully realized an increase in the load transfer amount, that there is a problem that evaluation is not possible in the structure by improving load transfer amount not stress distribution.

[0004] In addition, despite the fact that the design policy is to transmit the input load to other robust parts and to increase the absorbed energy due to the increase in the deformation energy associated therewith, in fact, the structure of the member that should actually receive the load Is not clearly reflected in the design policy, that is, the study of how to transmit the load to the structural members may not be fully reflected in the structure, resulting in extra deformation, There was a problem that the corresponding reinforcement had to be excessive.

The present invention has been made in view of such conventional problems, and a force called "transmitting force" different from stress and a path along which the transmitting force propagates through a structure. Using this concept, we propose an appropriate arrangement of structural members around the vehicle body structure, especially around the front floor. here,
"Transmission force path" refers to how the input load from the load point (load input point) is applied to the support point of the structure (in the case of a car body structure, it indicates the tire and the ground contact surface via the suspension). Whether or not to transmit is defined by a maximum value tracking line of a “relative stiffness” value evaluated by a stiffness distribution of constituent points (local points) inside the structure with respect to the deformation of the entire structure. Therefore, when the structure is evaluated based on the stress distribution as in the past, stress concentration occurs, for example, as in a circular hole opened in the structure. Even if it is large at that part, it cannot be evaluated that the amount of transmitted power of this local part has increased.The path obtained by tracking the maximum value of stress cannot necessarily be a part that is important for the rigidity of the entire structure. The inconsistency described above is removed, and the path of the transmission force referred to here is a sequence of important structural points that are conceptually assumed by the designer, ie, rationally expresses the load transmission path.

Also, a floor reinforcement structure for setting a load transmission path for clearly transmitting a load input from a side surface of the floor through a side sill or the like to the outside of the vehicle body structure, that is, to a suspension mounting portion, as a load transmission path, is provided. Think. In other words, the vehicle body floor structure is originally a shell structure. In order to maintain the in-plane and out-of-plane rigidity and strength of the shell as tensile rigidity, a seat which occurs as an unstable phenomenon due to a local input load such as at the time of a collision. Based on the above-described concept of the load transmission, a load transmission path is formed by extending the extension at the lower part of the front floor of the front side member, which has been reinforced to suppress bending, bending, etc., and the cross member located at the center of the front floor in the front-rear direction. The purpose of the present invention is to solve the above-mentioned problems by realizing a specific structure by using the above.

[0007]

In order to solve the above-mentioned problems, a vehicle floor reinforcing structure according to claim 1 forms a torque box together with a front floor, side members rigidly connected to the front floor, and the front floor. A dash panel, a rear floor that forms a rear (seat) cross member together with the front floor, a cross member reinforced so as to straddle a floor tunnel arranged in the center of the front floor in the left and right direction of the vehicle, and a left and right direction in the front and rear direction of the vehicle Two symmetrical front side members joined from the engine compartment and a rear side member supporting the rear floor are provided on the bottom of the vehicle body, which has an extension member rigidly joined from the torque box to the rear (seat) cross member via the cross member via the cross member. To the car body structure where Te, side sills, cross members,
The torque box and the rear (seat) cross member have sufficient strength to function as a structural member that bears the rigidity of deformation under the load from the side of the vehicle body, and the extension members are arranged such that the cross members are arranged from the rear end of the front side member. It is characterized by being firmly joined to the front floor so as to reach the rear (seat) cross member via the member's floor tunnel joint. According to a second aspect of the present invention, in the automobile floor reinforcing structure according to the first aspect, a new reinforcing member for connecting a cross member, a torque box, and a rear (seat) cross member to the front floor is also provided in parallel with the extension member. Characterized by having a bend.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. First, the structure will be described. In a vehicle floor vehicle body structure, a front floor 1 having a convex portion penetrating in the front-rear direction called a floor tunnel 8 at a vehicle body center is arranged at a lowermost side surface of a vehicle body called a side sill 3 at an outermost end surface. To the thin-walled structural member having a closed cross section through welding of a flange portion. Further, as seen in many automobile structures, a vehicle body structural member (a pillar for supporting a roof and side doors) extending in a substantially vertical direction called a center pillar 4 is disposed at the center of the side sill 3 in the front-rear direction and slightly behind. A cross member 2 is formed slightly forward of this position, that is, substantially at the center in the front-rear direction of the front floor 1 so as to form a closed cross section with the front floor 1 so as to connect both ends of the vehicle body, and to straddle the floor tunnel 8. In addition, at the front end of the front floor 1 at the front end of the side sill 3 and at the approximate center of the floor tunnel 8, two front side members 5 are provided on both left and right sides of the vehicle body, which are usually arranged at both lower ends of the engine compartment. Are three-dimensionally joined (see FIG. 2).

Here, both ends of the front end of the front side member 5 and the front end of the side sill 3 are often joined via a structure called a torque box 10. The torque box 10 is a closed space formed by both steel plates of a dash panel 9 which is disposed on the front floor 1 and a front end thereof in a vertically upward direction, and forms a partition separating an engine compartment and a cabin (cabin). However, in the present embodiment, by extending the torque box 10 to the floor tunnel 8, the front floor 1
, The side sill 3, the front side member 5, and the floor tunnel 8 are rigidly joined via the torque box 10 from the outside. As a result, the members and the floor tunnel 8 are coupled so as to rigidly receive the rotation about the axis perpendicular to the longitudinal direction of the vehicle body and the axis connecting the members and the displacement in the axial direction.

[0010] As seen in many car body structures, the rear end of the front floor 1 forms a box-shaped space with the front end surface of the rear floor arranged at a higher position with respect to the front floor 1 in the vertical direction. Thus, a structural member called a rear (seat) cross member 6 for transmitting a load in the left-right direction of the vehicle body is formed.

On the other hand, in a normal body structure, the front side member 5 is extended downward from the rear end of the front side member 5, that is, the front end of the front floor 1, and is offset downward with respect to the floor surface. The extension member 11 is arranged so as to be offset also in the left-right direction in some cases, and then straight rearward so as to form a closed sectional structure with the floor surface. However,
In the structure according to the present embodiment, instead of being offset in the left-right direction with respect to the floor surface, the joint with the front side member 5 has a gentle bend.
Thereafter, the extension member 11 is arranged so as to extend straight toward the joint of the floor member 8 of the cross member 2.

However, the cross member 2 is located on the upper surface of the floor,
Further, since the extension members 11 are arranged on the lower surface of the floor and each have a member structure of a closed section with one surface of the front floor, there is no direct joining of both members. further,
The extension direction of the extension member 11 changes gently at the position where the extension member 11 intersects the cross member 2, and is joined straight to the side end side sill 3 of the rear (seat) cross member 6 and the position substantially at the center of the center floor tunnel 8. To be placed. However, this structure is arranged symmetrically with respect to the floor tunnel 8.

The front side member 5 is rigidly connected to an engine mount, a suspension subframe or an upper spring damper mounting portion, and a rear side member 7 is provided at both ends of the rear (seat) cross member 6 and at the rear end of the side sill 3. The rear side member 7 is rigidly connected to a rear suspension or a suspension subframe.

Next, the operation will be described. Considering a vehicle collision on the side of the car body, especially near the center pillar 4, etc.
A load is input to the side sill 3 via the center pillar 4 and side doors to the front floor 1 of the vehicle body. In addition, the load input in the left-right direction of the vehicle body also acts on the roof side via each pillar (column), but many positions are considered due to the positional relationship of the center of gravity at the time of collision between the colliding object and the colliding object. It is assumed that the load acts on the floor side. Then, the input load is transmitted to each member set as a load transmission path in the vehicle body of the present embodiment. In other words, each member acts as a structural member that bears deformation rigidity on the floor surface.

In view of the above, the rigidity against deformation of the vehicle body in the present embodiment is determined by
Catch it as optimal. As is well known,
When a load is applied to a flat plate (assuming a floor surface) as shown in FIG. 3, a member arrangement that resists shearing deformation as shown in FIG. 3B is appropriate. The physical interpretation for this can be explained by the concept of "path of transmission force" described above. That is, when a load is applied to the flat plate structure as shown in FIG. 3A (support conditions are also considered), the path through which the load is transmitted is smoothly joined from the load point to the farthest part of the support point. In this case, it is shown that the contribution of the rigidity to the overall deformation of the constituent points of the structure (all local parts in the structure), that is, the “relative rigidity” is distributed continuously and without interruption. Therefore,
The rationality of the shape as shown in FIG. 3B can be understood as the continuity of the relative rigidity.

Since FIG. 3 shows a two-dimensional structure, deformation under such conditions actually causes an unstable phenomenon with respect to a load, ie, buckling out of the plane. become. However, in the vehicle body structure according to the present embodiment, by disposing the structural members on both sides of the floor surface as in the above-described configuration, the weight distribution of the structural cross section becomes three-dimensional, and the unstable deformation mode is caused. Can be suppressed.

With reference to this member arrangement, continuity of relative rigidity as shown in FIG. 4, that is, optimum structural member arrangement can be considered for a load input from the side of the vehicle body. Therefore,
The load input from the vicinity of the center of the side sill 3 (front-rear direction) is transmitted to the cross member 2, and further passes through the extension member 11 which is obliquely disposed from the rear end of the front side member 5 to the joint of the floor member 8 of the cross member 2. Thus, the torque is transmitted to the torque box 10 and the front side member 5 (see FIG. 5). On the other hand, when a local load is applied to the side of the vehicle body, the side sill 3 transmits the load due to the bending deformation of the side sill 3 or the displacement of the cross member 2 toward the floor tunnel 8, and the torque box 10 And the load is transmitted to the front side member 5. In this way, it is possible to increase the input load necessary for the vehicle body deformation by clarifying the sharing of the rigidity related to the vehicle body deformation and smoothly transmitting the input load to the outside of the vehicle body system. That is, local deformation is removed, and rigidity of the entire vehicle body is increased, so that the vehicle body absorbed energy accompanying the deformation can be increased.

The above-described load transmission mechanism (the operation of the present embodiment) simultaneously generates the operation of replacing the role of the torque box 10 with the rear (seat) cross member 6 for the same input load. Will be done. Therefore, the increase in vehicle body absorbed energy, which is an effect of the present embodiment, is reduced due to the disconnection of the extension member 11 halfway.

FIG. 6 shows a second embodiment. Embodiment 2 of FIG. 6 has the same structure and function as Embodiment 1,
Although it has a mechanism, the extension member 11 of the front side member 5 is connected to the front member 5 or the torque box 10 so that the input load from the side, which is the greatest advantage of the present embodiment, is transmitted from the cross member 2 to the front side member 5 or the torque box 10 more efficiently. They are arranged in parallel and with a similar bend. Therefore, an attempt is made to realize a structure having the same effect as in the first embodiment except that the load transmission paths are dispersed.

[0020]

As described above, according to the vehicle floor reinforcing structure of the present invention, the structure is such that the impact load received by the side collision is received by the side sill arranged on the side of the front floor, and the upper surface of the front floor is supported by the side sill. The load is transmitted to the front torque box and the rear rear (seat) cross member around the arranged cross member, and the extension member connected to the front side member and the center of the seat cross member through the floor tunnel of the cross member. Since the vehicle body floor reinforcement structure transmits the load via the vehicle, the input load is transmitted along the structural members along the path of the transmission force, so that the rigidity and the strength against rational deformation can be obtained and the vehicle body Clarify the sharing of rigidity related to deformation and input load By transferring smoothly out, it is possible to increase the input load required for the vehicle body deformation. That is, by removing local deformation and increasing rigidity of the entire vehicle body, the effect of increasing the vehicle body absorbed energy accompanying the deformation can be obtained. The automobile floor reinforcing structure of the present invention has the following effects in addition to the above effects. When the load is input from the front side member in the front direction of the vehicle, the load is transmitted to the cross member and the side sill via the extension member. This is because the relative stiffness value indicating the degree to which the constituent points of the structure described above contribute to the overall stiffness has continuity with respect to the load transmission path. This is because they have the matching of the transmission paths. Therefore, since the load transmission path is specified not only for side collisions but also for frontal collisions, the rigidity and strength of the dash panel and other structural members when the energy at the time of collision mainly absorbed by the front side members are shared among the structural members after the dash panel Can be raised.

[Brief description of the drawings]

FIG. 1 is a diagram showing a front floor reinforcing structure according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a connection between a front floor and a front side member according to the first embodiment.

FIG. 3 is a diagram showing a path of a transmission force in a flat plate.

FIG. 4 is a diagram showing a load transmission path on a front floor.

FIG. 5 is a diagram showing a load transmission path of the front floor reinforcing structure according to the first embodiment.

FIG. 6 is a diagram showing a front floor reinforcing structure according to a second embodiment.

FIG. 7 is a diagram showing a conventional automobile body floor structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front floor 2 Cross member 3 Side sill 4 Center pillar 5 Front side member 6 Rear (seat) cross member 7 Rear side member 8 Floor tunnel 9 Dash panel 10 Torque box 11 Extension member

Claims (2)

[Claims] 1. A front floor, side members rigidly joined thereto, a dash panel forming a torque box together with the front floor, a rear floor forming a rear (seat) cross member together with the front floor, A cross member reinforced so as to straddle the floor tunnel arranged in the center of the front floor, and an extension member rigidly joined from the torque box to the rear (seat) cross member via the cross member from the torque box symmetrically in the vehicle longitudinal direction. An automobile body structure in which two symmetrical front side members joined from an engine compartment and a rear side member supporting a rear floor are joined to a vehicle body bottom having a side sill, a cross member, a torque box and a rear (seat) cross. member It has sufficient strength to function as a structural member that bears the rigidity of deformation against the load from the side of the vehicle body, and the extension member is located from the rear end of the front side member through the floor tunnel joint of the cross member to the rear ( Seat) An automobile floor reinforcement structure which is firmly joined to a front floor so as to reach a cross member. 2. The vehicle floor reinforcing structure according to claim 1, wherein a new reinforcing member for connecting a cross member, a torque box, and a rear (seat) cross member to the front floor is similarly bent in parallel with the extension member. An automobile floor reinforcement structure characterized by being arranged to have.