JP5668583B2 - Lower body structure - Google Patents

Description

  The present invention relates to a vehicle body lower structure in which an impact absorbing member is disposed at an end portion in a vehicle longitudinal direction.

  A front vehicle body lower structure is known in which a frontal collision load input to a front side member is distributed to a tunnel member via an inner torque box and to a rocker rail via an outer torque box (for example, a patent) Reference 1).

JP 2005-162144 A

  In the configuration in which the front collision load is received by the pair of left and right front side members, it is difficult to efficiently transmit the collision load to the anti-collision side, for example, in the case of an offset collision or an oblique collision.

  An object of the present invention is to obtain a vehicle body lower structure that can efficiently absorb and disperse a load of a front or rear collision including an offset collision or an oblique collision and transmit the load to an underbody.

  The vehicle body lower part structure according to the first aspect of the present invention includes an underbody in which a standing wall is erected upward in the vehicle vertical direction from an end portion of the floor portion in the vehicle front-rear direction, and is elongated in the vehicle width direction. A load transmission member coupled to the underbody in a state of surface contact or line contact along the vehicle width direction with respect to an outward surface in the vehicle front-rear direction, and a load transmission member that is elongated in the vehicle width direction and the load transmission The shock absorbing member coupled to the opposite side of the vehicle front-rear direction in the member and configured to open in a direction opposite to the load transmission member side in a cross section along a plane perpendicular to the longitudinal direction; And a cover member that is joined to the opening end side of the shock absorbing member and forms a closed cross section with the shock absorbing member in a sectional view along a plane orthogonal to the longitudinal direction.

  In the vehicle body lower part structure according to the first aspect, the load transmission member is coupled to at least one of the front end side and the rear end side of the underbody, and the shock absorbing member is coupled to the load transmission member. When a collision load is input to the impact absorbing member, the load is transmitted to the standing wall of the underbody via the load transmitting member.

Here, since both the impact absorbing member and the load transmitting member are elongated in the vehicle width direction, a deformation mode in which the impact absorbing member is bent in the front-rear direction does not occur when absorbing the impact collision energy). , It is stably compressed in the front-rear direction (axial compression is stable). Moreover, the load transfer member is a state along the surface contact or the vehicle width direction is a line contact against the upright wall of the under body. For this reason, the collision load is efficiently distributed in the vehicle width direction and input to the underbody regardless of the input position and the input angle in the vehicle width direction.

  Thus, in the vehicle body lower structure, it is possible to efficiently absorb and disperse the load of the front or rear collision including the offset collision and the oblique collision and transmit it to the underbody. In the lower structure of the vehicle body, the shock absorbing member is opened outward in the vehicle longitudinal direction, that is, toward the input side of the collision load. For this reason, the shock absorbing member can be structured to be long in the vehicle width direction on the load input side, which contributes to distributing the load input in a wide range in the vehicle width direction and transmitting it to the underbody. In addition, since the shock absorbing member has a closed cross section with the cover member, the required shock absorbing function can be achieved.

  A vehicle body lower structure according to a second aspect of the present invention is the vehicle body lower structure according to the first aspect, wherein the cover member is a bumper cover.

  In the vehicle body lower structure according to claim 2, since the bumper cover serves as the cover member, it contributes to the reduction of the number of parts and the downsizing in the front-rear direction.

  A vehicle body lower structure according to a third aspect of the invention is the vehicle body lower structure according to the first aspect, wherein the cover member is configured as a separate member from the bumper cover and is spaced apart from the bumper cover in the front-rear direction. Has been.

  In the vehicle body lower part structure according to the third aspect, the closed section is formed by the impact absorbing member independently of the cover member bumper cover. Since the closed cross section formed by the cover member, that is, the shock absorbing member, is separated from the bumper cover in the front-rear direction, the light collision load is not transmitted to the closed cross section, which contributes to the improvement of damage ability against the light collision.

A vehicle body lower structure according to a fourth aspect of the invention is the vehicle body lower structure according to any one of the first to third aspects, wherein the impact absorbing member is arranged such that the cover member side is on the load transmission member side in plan view. It has a tapered shape that is longer in the vehicle width direction.

  In the vehicle body lower part structure according to the fourth aspect, since the load input side is long in the vehicle width direction, the load input in a wide range in the vehicle width direction can be dispersed and transmitted to the underbody. That is, it contributes to receiving the load of the front or rear collision including offset collision and oblique collision in a wide range in the vehicle width direction and efficiently absorbing and dispersing and transmitting it to the underbody.

  As described above, the vehicle body lower structure according to the present invention has an excellent effect of being able to efficiently absorb, disperse and transmit the load of the front or rear collision including offset collision and oblique collision to the underbody. .

It is a sectional side view which shows the principal part of the vehicle body lower structure which concerns on the 1st Embodiment of this invention. It is a top view which shows the principal part of the vehicle body lower structure which concerns on the 1st Embodiment of this invention. It is a perspective view of the front EA member which comprises the vehicle body lower part structure concerning the 1st Embodiment of this invention. It is a sectional side view which shows the principal part of the vehicle body lower structure which concerns on the 2nd Embodiment of this invention.

  A vehicle body lower structure 10 as a vehicle body lower structure according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. Note that an arrow FR appropriately shown in the drawing indicates a forward direction in the vehicle longitudinal direction, an arrow UP indicates an upward direction in the vehicle vertical direction, and an arrow W indicates a vehicle width direction. In the following description, when using the front-rear direction and the up-down direction unless otherwise specified, the front-rear direction of the vehicle and the up-down direction of the vehicle are indicated.

  FIG. 1 is a sectional side view of a front portion of a vehicle V to which the vehicle body lower structure 10 is applied. FIG. 2 is a schematic plan view of the front portion of the vehicle V. Yes. As shown in these drawings, the underbody structure 10 includes an underbody 12, a front suspension module 14, and a front energy absorbing member (hereinafter referred to as “front EA member”) 16 as main parts.

(Configuration of underbody)
The underbody 12 has a floor portion 18 having a substantially rectangular shape in plan view, a dash lower portion 20 as a standing wall standing upward from the front end of the floor portion 18, and standing upward from the rear end of the floor portion 18. And a lower back portion (not shown). The dash lower portion 20 and the lower back portion have a length that extends over substantially the entire width of the floor portion 18, and form a substantially rectangular shape that is long in the vehicle width direction when viewed from the front. Although not shown, the underbody 12 is formed in a bathtub shape as a whole (a bathtub shape with a part of the side wall cut off).

  The underbody 12 in this embodiment is made of a resin material. As a resin material constituting the underbody 12, for example, a fiber reinforced resin containing reinforcing fibers such as carbon fiber, glass fiber, and aramid fiber may be used.

  The underbody 12 in this embodiment is configured by superposing and joining a lower panel 12L and an upper panel 12U in the vertical direction. The floor portion 18 and the dash lower portion 20 of the underbody 12 each have a closed cross-sectional structure as shown in FIG. Although illustration is omitted, the floor portion 18 has a plurality of closed cross-section portions (frame portions) elongated in the front-rear direction and arranged in parallel in the vehicle width direction. In this embodiment, rockers positioned at both ends in the vehicle width direction and a center skeleton positioned in the center in the vehicle width direction are formed on the floor portion 18.

  As a result, the underbody 12 is configured such that a rearward load input to the dash lower portion 20 which is a wall having a forward closed cross-sectional structure is distributed to each skeleton portion of the floor portion 18 and transmitted to the rear of the vehicle body. Yes.

(Configuration of suspension module)
The front suspension module 14 includes at least a suspension member 26 as a load transmission member and a pair of left and right front suspensions (not shown). The suspension member 26 is elongated in the vehicle width direction and has a closed cross-sectional structure in a side cross-sectional view as shown in FIG. As shown in FIG. 2, attachment portions 26 </ b> A to which the front suspension is assembled are provided at both ends of the suspension member 26 in the vehicle width direction.

  Although not shown, the suspension member 26 constitutes the front suspension module 14 by supporting the front wheels Wf via the front suspension so as to be steerable. In this embodiment, the left and right front suspensions are assembled to the left and right attachment portions 26A of the suspension member 26 as a whole. That is, each front suspension is supported by the suspension member 26 so as to function independently without depending on other parts constituting the vehicle body of the automobile V.

  As shown in FIG. 1, the suspension member 26 is fixedly coupled to the dash lower portion 20 of the underbody 12 by fastening or the like at the rear wall 26 </ b> R constituting the closed cross section. An attachment piece 28 extends rearward from the lower wall 26L constituting the closed cross section of the suspension member 26, and the attachment piece 28 is fastened to the lower wall 12LL of the lower panel 12L constituting the underbody 12. It is fixed by.

(Configuration of EA member)
As shown in FIGS. 1 to 3, the front EA member 16 as an impact absorbing member is a large component that is elongated in the vehicle width direction. Specifically, the front EA member 16 is formed in a substantially rectangular shape in a plan view and a front view, and has a box shape that opens forward of the vehicle. The length of the front EA member 16 in the vehicle width direction is equal to the length of the suspension member 26 in the vehicle width direction.

  More specifically, the front EA member 16 has a hollow structure surrounded by an upper wall 16U, a lower wall 16L, and a pair of side walls 16S facing left and right. The rear end of the front EA member 16 is closed by a rear wall 16R connected to the rear ends of the upper wall 16U, the lower wall 16L, and the pair of side walls 16S. The front EA member 16 is fixedly coupled to the front wall 26F facing the rear wall 26R of the suspension member 26 at the rear wall by fastening or the like. The front EA member 16 may be fastened (co-fastened) to the underbody 12 (suspension member 26) by fastening means common to the suspension member 26.

  Each part of the front EA member 16 is integrally formed of a resin material. As a resin material constituting the front EA member 16, for example, a fiber reinforced resin containing reinforcing fibers such as carbon fiber, glass fiber, and aramid fiber may be used. The front EA member 16 may be made of a metal material such as aluminum or an alloy thereof.

  As shown in FIG. 2, the front EA member 16 is configured such that the front end, that is, the length Lf in the vehicle width direction at the opening end 16O is longer than the length Lr in the vehicle width direction at the rear end (rear wall 16R). ing. That is, the front EA member 16 has a double-tapered shape (symmetrical taper) that spreads forward in plan view as shown in FIG. Thereby, the front EA member 16 is configured such that the input side of the front impact load is wider in the vehicle width direction than the fixed end to the suspension member 26 (underbody 12).

  Further, in this embodiment, as shown in FIG. 1, the front EA member 16 is configured such that the vertical height at the opening end 16O is higher than the vertical height at the rear end (rear wall 16R). That is, the front EA member 16 has a double-tapered shape (a taper that is vertically symmetrical) in a side view.

  With the above tapered shape, the front EA member 16 has a shape that can be removed (demolded) from the molding die.

  The opening end 16O of the front EA member 16 described above is closed by a bumper cover 30 as a cover member. Specifically, a flange 16F projects outward from the opening end 16O of the front EA member 16, and a plurality of locking holes 16H as locking portions are formed in the flange 16F. On the other hand, from the back surface of the bumper cover 30, a locking piece 30 </ b> F with a locking claw as a locked portion locked in the locking hole 16 </ b> H protrudes.

  The bumper cover 30 is configured to close the opening end 16O of the front EA member 16 while being held by the front EA member 16 by locking (snap-fit) each locking piece 30F to the corresponding locking hole 16H. Has been. The bumper cover 30 and the front EA member 16 may be coupled by other structures such as a clip structure. Further, when both the front EA member 16 and the bumper cover 30 are made of a resin material, they may be bonded together by adhesion or the like.

  Next, the operation of the first embodiment will be described.

  In the vehicle V to which the vehicle body lower structure 10 having the above configuration is applied, when a frontal collision occurs, a collision load is input to the front EA member 16 via the bumper cover 30. The front EA member 16 is compressed and deformed by this load, and transmits a load (support reaction force) to the suspension member 26 while absorbing impact energy (dynamic load). The load transmitted to the suspension member 26 is transmitted to the skeleton portion (closed section) of the floor portion 18 through the dash lower portion 20.

  In the vehicle body lower structure 10, since the collision load input to the front EA member 16 is received by the wide surface of the suspension member 26 (the front wall 26F long in the vehicle width direction), the front EA member 16 is stably subjected to axial compression deformation. Is done. For example, in a comparative example in which a collision load from a bumper reinforcement that is elongated in the vehicle width direction is received by a pair of left and right side members (transmitted rearward), a load in a direction of bending a long side member in the front-rear direction acts. For this reason, in this comparative example, in order to absorb collision energy efficiently, many frame members and reinforcement members are required.

  On the other hand, in the vehicle body lower structure 10, the load input to the box-shaped front EA member 16 that is longitudinal in the vehicle width direction is transmitted to the wide surface of the suspension member 26 while being dispersed in the longitudinal direction of the front EA member 16. It is done. That is, the load input to the bumper cover 30 is received by the wide surface of the suspension member 26 while compressing the box-shaped portion formed including the upper wall 16U, the lower wall 16L, and the pair of side walls 16S as a whole. . Thus, in the vehicle body lower structure 10, the front EA member 16 absorbs the collision energy while dispersing the collision load in the vehicle width direction as a primary load distribution member.

  For this reason, the front EA member 16 and the suspension member 26 are unlikely to be bent like the side member of the comparative example. That is, as described above, the front EA member 16 is stably axially compressed and deformed. The front EA member 16 also disperses the load in the vehicle width direction and compresses the suspension in the vehicle width direction through the bumper cover 30 against a collision load caused by an offset collision or an oblique collision. Communicate to 26 wide areas. That is, even in the case of an offset collision or an oblique collision, the front EA member 16 is stably axially compressed and deformed.

  Further, in the vehicle body lower structure 10, the load from the front EA member 16 is dispersed in the vehicle width direction by the suspension member 26 and transmitted to the dash lower portion 20, that is, the underbody 12. That is, the suspension member 26 functions to transmit a load to the underbody 12 as a secondary load distribution member. For this reason, in the vehicle body lower structure 10, a collision load accompanying an offset frontal collision or an oblique collision is also received by a wide surface of the suspension member 26, and the underload is efficiently dispersed in the vehicle width direction by the suspension member 26. It can be transmitted to the body 12 side. That is, in the above comparative example, the load due to the offset frontal collision or the oblique collision is likely to act in the direction in which the side member is bent. On the other hand, in the vehicle body lower structure 10, the load is distributed in the vehicle width direction even in the case of an offset frontal collision or an oblique collision, so that an efficient load transmission to the underbody 12 side is achieved.

  Moreover, in the vehicle body lower structure 10, since the load is distributed in the vehicle width direction and transmitted to the underbody 12 as described above, the dash lower portion 20 of the underbody 12 is locally deformed in a part in the vehicle width direction. Is prevented or effectively suppressed. For this reason, the amount of intrusion (retreat) of the dash lower portion 20 into the local compartment is reduced, and the amount of deformation of the compartment is kept small even after a frontal collision. Further, as described above, the load dispersed by the suspension member 26 in the vehicle width direction and transmitted to the dash lower portion 20 is transmitted substantially evenly to each skeleton portion (left and right rockers, center skeleton) of the floor portion 18. Thereby, the uneven deformation of the passenger compartment is prevented or effectively suppressed.

  Here, in the vehicle body lower structure 10, the front EA member 16 is configured to open forward (opposite to the suspension member 26 side). For this reason, the front EA member 16 can increase the length Lf in the vehicle width direction at the opening end 16O on the input side of the collision load, as compared with the configuration in which the front EA member 16 is opened rearward. That is, the front EA member molded by the mold needs to be wider on the opening side than on the closing side in consideration of removal from the mold. For this reason, in the front EA member according to the comparative example in which the front end side is closed (opens rearward), the front end side that is the load input side is bulged, and it is difficult to ensure the length in the vehicle width direction. Specifically, in the front EA member according to the comparative example in which the front end side is closed, as indicated by an imaginary line in FIG. 2, the front EA member 16 has a reverse taper and the vehicle width direction length Lr on the closed side is reduced. In the case of equalization, the length on the front end side is reduced by ΔL shown in FIG.

  On the other hand, in the vehicle body lower structure 10, since the front EA member 16 opens forward, the length Lf in the vehicle width direction at the opening end 16O can be increased as compared with the comparative example as described above. it can. As a result, a wide range of collision loads in the vehicle width direction can be received by the front EA member 16, and robustness against frontal collisions including offset collisions and diagonal collisions is improved.

  Further, since the opening end 16O of the front EA member 16 is closed by the bumper cover 30, it is possible to prevent or effectively prevent the front EA member 16 that opens to the load input side from opening in the process of shock absorption. It is suppressed.

  Furthermore, since the bumper cover 30 also serves as a cover member that closes the open end 16O, the opening of the front EA member 16 can be prevented or effectively suppressed without increasing the number of components. Furthermore, since the bumper cover 30 is directly coupled to the front EA member 16, the overall configuration can be made compact in the front-rear direction. On the other hand, since the bumper cover 30 is coupled to and supported by the front EA member 16, the rigidity against bending and twisting of the automobile V to which the vehicle body lower structure 10 is applied is improved. In other words, the bumper cover 30 is reinforced by the front EA member 16.

(Other embodiments)
Next, a vehicle body lower structure 50 according to a second embodiment of the present invention will be described. Note that parts and portions that are basically the same as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  FIG. 4 shows a vehicle body lower structure 50 according to the second embodiment in a side sectional view corresponding to FIG. As shown in this figure, the vehicle body lower structure 50 is configured such that the opening end 16O is closed by a cover member 54 independent of the bumper cover 52, instead of the configuration in which the bumper cover 30 closes the opening end 16O. Thus, it differs from the vehicle body lower structure 10 according to the first embodiment.

  In the example shown in FIG. 4, the cover member 54 has a cross-sectional hat shape that opens rearward in a side sectional view, and the flange 54 </ b> F protruding from the opening end is abutted against the flange 16 </ b> F of the front EA member 16. Yes. The flange 54F is coupled to the flange 16F by means such as snap-fit, clip, or adhesion, whereby a closed cross-sectional structure of the front EA member 16 and the cover member 54 is configured. Note that the cover member 54 may be a flat plate with the front-rear direction being the plate thickness direction.

  The bumper cover 52 is separated from the cover member 54 in the front-rear direction and constitutes a front bumper. That is, the bumper cover 52 is configured so as not to transmit a load to the cover member 54 and the front EA member 16 (including arrangement), although it deforms itself during a light collision. The other structure of the vehicle body lower structure 50 is basically the same as the corresponding structure of the vehicle body lower structure 10 including a portion not shown.

  Therefore, the vehicle body lower structure 50 according to the second embodiment also has the same effect as the vehicle body lower structure 10 except for the operation effect obtained by the configuration in which the bumper cover 30 closes the opening end 16O of the front EA member 16. Can be obtained. Further, in the vehicle body lower structure 50, the bumper cover 52 performs the impact absorption by itself in the event of a light collision, so that the bumper cover 52 needs to be replaced for repair. Thereby, in the automobile V to which the vehicle body lower structure 50 is applied, the damage ability against a light collision is improved.

  In each of the above-described embodiments, the example in which the present invention is applied to the front portion of the vehicle has been shown. However, the present invention is not limited to this, and may be applied to the rear portion of the vehicle or both the front portion and the rear portion. In these cases, a lower back portion of the underbody 12 corresponds to the standing wall on the rear side, and a rear suspension member can be applied as a load transmission member. The rear EA material has a shape that opens rearward, which is the input side of the rear impact load, and is closed at the front end, which is the fixed side to the rear suspension member. The rear opening end of the rear EA material is closed by a rear bumper cover or a cover member independent of the rear bumper cover.

  In each of the above-described embodiments, the example in which the suspension member 26 having a flat and wide forward surface is employed as the load transmission member has been described. However, the present invention is not limited to this. For example, a part other than the suspension member (including a case where it is a dedicated part) may be used as the load transmission member, and for example, a member having a rectangular frame shape (including a case where the suspension member is a suspension member) may be used as the load transmission member. ) May be used. That is, the load transmission member may be configured to be coupled to the front EA member 16 in a surface contact or line contact state along the vehicle width direction so as to achieve the secondary load distribution described above.

  In addition, it goes without saying that the present invention is not limited to the specific configuration in the above-described embodiment, and can be implemented with various modifications.

10 Undercarriage 12 Underbody 16 Front EA member (Shock absorbing member)
16O Open end 18 Floor 20 Dash lower (standing wall)
26 Suspension member (load transmission member)
30 Bumper cover (cover member)
50 Lower body structure 52 Bumper cover 54 Cover member

Claims (4)

An underbody in which a standing wall is erected upward from the end in the vehicle front-rear direction in the floor portion in the vehicle vertical direction
A load transmitting member coupled to the underbody in a state of being longitudinal in the vehicle width direction and in line contact with the surface facing the vehicle front-rear direction on the standing wall or in line with the vehicle width direction;
The longitudinal direction of the load transmission member is coupled to the opposite side of the vehicle longitudinal direction in the vehicle width direction, and is opposite to the load transmission member side in a cross section along a plane perpendicular to the longitudinal direction. An impact absorbing member having an opening shape;
A cover member which is joined to the opening end side of the shock absorbing member and forms a closed cross section in a cross sectional view along a plane perpendicular to the longitudinal direction with the shock absorbing member;
Body lower structure with   The vehicle body lower part structure according to claim 1, wherein the cover member is a bumper cover.   The vehicle body lower part structure according to claim 1, wherein the cover member is configured as a separate member from the bumper cover and is spaced apart from the bumper cover in the front-rear direction. The vehicle body lower structure according to any one of claims 1 to 3, wherein the shock absorbing member has a tapered shape in which the cover member side is longer in the vehicle width direction than the load transmission member side in a plan view. .

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