JP2003146241A - Vehicle body front structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body front structure that can surely axially collapse a front end portion of a side member even against an input of collision load from the diagonal front direction and that can increase absorption efficiency of collision energy. SOLUTION: The maximum stress generated at front portions and rear portions of virtual cross sections Ia to Ie that continue in the longitudinal direction of a side member front area 11F is set so that the strength of each of the front portions is not less than or similar to each of the rear portions by a strength adjusting means 50 placed on the side member front area 11F. Accordingly, when collision load is input from the diagonal front direction to the front end portion of the side member 11, collapse is induced toward the rearward from the front end of the side member front area 11F functioning as an input point and the collapse is propagated continuously to the rear portion of the side member front area 11F so that the absorption efficiency of the collision energy is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body front structure.

[0002]

2. Description of the Related Art As a countermeasure against a vehicle collision, the side members at the front of the vehicle body are axially crushed to absorb the collision energy. For example, Japanese Patent Laid-Open No. 2001-158.
Japanese Laid-Open Patent Publication No. 377 discloses the front structure of the vehicle body.

In this vehicle body front structure, a bead is arranged on the wall portion of the side member front portion having a polygonal cross section to promote axial crushing when an axial input is applied to the side member, thereby colliding energy. Is designed to absorb.

[0004]

However, in such a conventional vehicle body front structure, it is possible to favorably absorb energy against a collision load applied to the side member in the axial direction, but the energy is applied obliquely from the front. With respect to a collision load, there is a tendency that the front portion of the side member is in a deformation mode in which it bends from its root portion.

Therefore, the collision energy at the time of an oblique collision is only temporarily absorbed by the bending of the front portion of the side member, and it becomes difficult to obtain the load characteristic of continuously absorbing the collision load by axial crushing.

Therefore, in order to obtain sufficient collision energy absorption characteristics only by bending the front portion of the side member,
Since it is necessary to significantly increase the rigidity of the side members,
Inevitably, there is a concern that the thickness of the side member will become thicker and the weight of the vehicle body will increase significantly.

Therefore, the present invention provides a vehicle body front structure capable of reliably axially crushing the front end portions of the side members even when a collision load is input from diagonally forward, thereby enhancing the efficiency of absorbing collision energy. To do.

[0008]

According to a first aspect of the present invention, there is provided a vehicle body having reinforcing members for mounting vehicle unit parts on side members arranged in front and rear directions of the vehicle body on both left and right sides of the front compartment. In the front part structure, the maximum stress generated in the front part and the rear part of the virtual cross section which is continuous in the longitudinal direction in the front region of the side member, which is located forward from the reinforcing portion of the side member, is such that the front part is equal to or more than the rear part, or close to this. It is characterized in that strength adjusting means for adjusting the strength of the state is provided.

According to a second aspect of the invention, in the vehicle body front structure according to the first aspect, the upper limit value of the maximum stress by the strength adjusting means is set based on the yield strength of the material forming the side member. It is characterized by having done.

According to the invention of claim 3, claims 1 and 2 are provided.
In the vehicle body front structure described in,
It is characterized by a side member plate thickness changing structure in which the plate thickness distribution in the front region of the side member is changed in the longitudinal direction.

According to a fourth aspect of the present invention, in the vehicle body front structure according to the third aspect, the side member plate thickness changing structure includes a plurality of plate members having different plate thicknesses in a stepwise manner. It is characterized in that the composite panel material bonded so as to change is configured such that the changing direction of the plate thickness is the longitudinal direction.

According to the invention of claim 5, claims 1 and 2 are provided.
In the vehicle body front structure described in,
A partition plate thickness changing structure in which a plurality of partition plates are arranged in the closed cross section of the front region of the side member at appropriate intervals in the longitudinal direction, and the plate thickness of each partition plate is changed in the longitudinal direction of the side member. I am trying.

According to the invention of claim 6, claims 1 to 5 are provided.
In the vehicle body front structure described in (1), the strength adjusting means is a cross-sectional dimension changing structure in which the cross-sectional dimension of the side member front region is changed in the longitudinal direction.

According to a seventh aspect of the present invention, in the vehicle body front structure according to the first or second aspect, the side member front region is formed by an extruded material whose extruded plate thickness and extruded cross-sectional dimension continuously change in the extruding direction. Is formed to change the plate thickness or the cross-sectional dimension of the front region of the side member, or both the plate thickness and the cross-sectional dimension are changed to constitute the strength adjusting means.

According to the invention of claim 8, claims 1 to 7 are provided.
In the vehicle body front structure described in (1), the maximum stress setting by the strength adjusting means is assumed on the assumption that static input is statically applied to the front end portion of the side member, and is set to each virtual cross section continuous in the longitudinal direction of the side member front region. The feature is that the calculated value is applied by considering both the generated axial force component stress and the generated moment component stress.

In the invention of claim 9, claims 1 to 8
In the vehicle body front structure described in [1], the side member front regions of the left and right side members are formed straight in the vehicle body front-rear direction, and are arranged parallel to each other.

According to the invention of claim 10, claim 1
In the vehicle body front structure described in any one of 8 above, the side member front regions of the left and right side members are formed so as to be inclined outward in the vehicle width direction toward the front of the vehicle body.

[0018]

According to the first aspect of the present invention, the maximum stress generated at the front and rear portions of the virtual cross section continuous in the longitudinal direction of the side member front region by the strength adjusting means provided in the side member front region. However, since the front part is set to have a strength equal to or more than the rear part or close to this, when a collision load is input diagonally from the front end of the side member, the front end of the side member front region, which is the input point, is input. The crushing is induced from the rear side to the rear side, and the crushing can be continuously propagated to the rear part of the front region of the side member to enhance the absorption efficiency of the collision energy.

Of course, even when a collision load is axially input to the front end portion of the side member from the front direction, axial crushing is similarly induced over the entire front region of the side member to effectively absorb the collision energy. At the same time, since the rear end of the side member front region provided with the strength adjusting means is a reinforcing portion for mounting vehicle unit parts, the rigidity characteristic of this reinforcing portion is utilized to make the side member. Can be reasonably configured.

According to the invention of claim 2, claim 1
In addition to the effect of the invention, since the upper limit of the maximum stress by the strength adjusting means is set based on the yield strength of the material forming the side member, when inputting to the front end of the side member, first, Since the vicinity of the front end reaches the yield region of the material and plastic deformation occurs, it is possible to more reliably induce crushing from the front end of the front region of the side member at the time of collision.

According to the third aspect of the invention, in addition to the effects of the first and second aspects of the invention, the strength adjusting means changes the plate thickness distribution in the front region of the side member in the longitudinal direction. The member thickness change structure makes it easy to control the maximum stress generated in the virtual cross section that is continuous in the longitudinal direction of the front area of the side member when a collision load is input to the front end of the side member. Can be easily adjusted, and the collapse from the front end of the front region of the side member at the time of collision can be more reliably induced.

According to the invention of claim 4, claim 3
In addition to the effect of the invention described above, a composite panel material obtained by joining the side member plate thickness changing structure to a plurality of plate materials having different plate thicknesses so that the plate thicknesses thereof are changed stepwise is Since it is configured to be in the longitudinal direction, the maximum stress generated in the virtual cross section that is continuous in the longitudinal direction of the front region of the side member is approximately controlled, and crushing from the front end of the front region of the side member is induced without problems. In addition, the side member front region provided with such strength adjusting means can be easily formed.

According to the invention of claim 5, in addition to the effects of the inventions of claims 1 and 2, a plurality of the strength adjusting means are provided at appropriate intervals in the longitudinal direction within the closed cross section of the front region of the side member. The partition plates are arranged and the thickness of each partition plate is changed in the longitudinal direction of the side member, so that when the collision load is input to the front end of the side member, The maximum stress generated in the imaginary cross section that is continuous in the longitudinal direction of the area can be controlled by each partition plate, which in turn makes it easier to adjust the strength balance and prevent crushing from the front end of the side member front area during a collision. Can be surely triggered.

According to the invention of claim 6, claim 1
In addition to the effects of the inventions of 5 to 5, since the strength adjusting means has a cross-sectional dimension changing structure in which the cross-sectional dimension of the side member front region is changed in the longitudinal direction, the collision load is input to the front end portion of the side member. At this time, it becomes easier to control the maximum stress generated in the virtual cross section that is continuous in the longitudinal direction of the front region of the side member, and it becomes easier to adjust the strength balance.
It is possible to more reliably induce crushing from the front end of the front region of the side member at the time of collision, and to change the cross-sectional dimension that is more sensitive to the member cross-section constant than the plate thickness, and Further weight reduction can be achieved.

According to the invention described in claim 7, in addition to the effects of the inventions of claims 1 and 2, in the extruding section, the extruded plate thickness and the extruded sectional size continuously change in the extruding direction in the front region of the side member. Since the strength adjusting means is formed of a material, the plate thickness distribution or the cross-sectional dimension can be freely adjusted in the longitudinal direction, and the change can be continuously performed, so that the plate thickness change Can be performed with high accuracy, the maximum stress generated in the virtual cross section continuous in the longitudinal direction of the front region of the side member can be adjusted with high accuracy, and further structural rationalization and weight reduction can be achieved.

According to the invention described in claim 8, claim 1
In addition to the effects of the inventions of 7 to 7, the maximum stress setting by the strength adjusting means is assumed assuming that a diagonal input is statically applied to the front end portion of the side member, and each virtual cross section that is continuous in the longitudinal direction of the front region of the side member. Since the value calculated by considering both the axial force component stress and the moment component stress generated in the side member is applied, if the collision load from the diagonal front is input to the front end of the side member, Crushing from the front end can be reliably induced with higher accuracy.

According to the invention of claim 9, claim 1
In addition to the effects of the inventions of 8 to 8, since the side member front regions of the left and right side members are formed straight in the vehicle front-rear direction and are arranged parallel to each other, the collision load from the front direction is applied to the front end of the side member. The side member front region can be continuously crushed from the tip end portion not only when it acts on the portion, but also when it strikes obliquely from the front, and good energy absorption characteristics can be secured.

According to the invention described in claim 10, in addition to the effects of the inventions of claims 1-8, the side member front region of the side member is inclined outward in the vehicle width direction toward the front of the vehicle body. Therefore, the front region of the side member can be continuously crushed from the tip portion not only when the vehicle strikes diagonally from the front, but also when the vehicle strikes from the front direction. In particular, the side member inclined outward in the vehicle width direction can be crushed. The front region allows the input support range at the front end of the vehicle body to be expanded in the vehicle width direction.

Further, since the front region of the side member is inclined outward in the vehicle width direction from the reinforcing portion on which the vehicle unit component is mounted, input of a collision load to the side member is performed from the reinforcing portion to the vehicle unit component, and further. Can be transmitted to the other reinforcing portion and the other side member via this vehicle unit component, so that the collision load can be dispersed and supported in a wide portion of the front portion of the vehicle body.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) FIGS. 1 to 10 show a first embodiment of a vehicle body front structure of the present invention. FIG. 1 is an external perspective view of an automobile to which the present invention is applied, and FIG. 3 is a schematic plan explanatory view showing the skeleton structure on the right side of the portion, FIG. 3 is a perspective view of the front region of the side member, FIG. 4 is an enlarged cross-sectional view taken along the line AA in FIG. 3, and FIG. FIG. 6 is an explanatory view showing a morphological model (a) and a stress distribution diagram (b), FIG. 6 is a stress distribution diagram showing the concept of the strength adjusting means, and FIG. 7 is a vehicle front right side showing an input form at the time of frontal collision and oblique frontal collision. FIG. 8 is a schematic plan explanatory view of FIG. 8, FIG. 8 is an explanatory view showing a deformation mode of a side member that is conventionally seen, and FIG. 9 is a deformation of the side member during a frontal collision (a) and an oblique frontal collision (b) of the present embodiment. FIG. 10 is an explanatory view showing the mode, and FIG. 10 shows a front collision and a diagonal front collision of the side member. Energy is a graph comparing the uptake versus time in the prior (a) and the embodiment (b).

The vehicle body front structure of this embodiment is applied to the front compartments F and C of the vehicle body 10 shown in FIG.
As shown in FIG. 2, the skeleton structure includes side members 11 arranged on both left and right sides in a straight line in the vehicle front-rear direction, and these side members 11 are arranged in parallel and each side member 11 A bumper reinforcement 12 forming a skeleton of a bumper (not shown) is connected across the front end of the.

Further, extension side members 13 that extend from the dash panel 17 to the lower surface side of the floor panel 18 are connected to the rear side of each side member 11, and each extension side member 13 is provided.
The side sills 14 are arranged substantially parallel to each other on the outer side in the vehicle width direction, and the front end portions of the extension side members 13 and the side sills 14 are respectively attached to the outriggers 15.
It is combined with.

A dash cross member 16 is connected so as to straddle the continuous portions of the side members 11 and the extension side members 13.

A front wheel 2 is provided on the rear side of the side member 11.
A suspension arm 21 for supporting 0 is attached directly or via a suspension member (not shown), and a power unit 30 such as an engine as a vehicle unit component is mounted via a mount bracket 31 between the left and right side members 11. To be done.

As shown in FIG. 3, the side member 11 is provided with a reinforcing portion 11R (shown as a satin portion in FIG. 3) in which the wall thickness of the side member 11 is increased at the mounting portion of the mount bracket 31.

That is, as shown in FIG. 3, the side member 11 is closed by fixing both side flange portions of the second plate 11b having a U-shaped cross section to the first plate 11a having a flat plate shape by spot welding or the like. It is formed as a cross-sectional structure, and the reinforcing portion 11R is formed by joining and disposing a reinforcing plate on the inner peripheral surface.

Here, in this embodiment, the imaginary cross sections Ia, I extending in the longitudinal direction extend from the reinforcing portion 11R of the side member 11 to the front side member front region 11F.
b ... The side member plate thickness changing structure 50 is configured as a strength adjusting means so that the maximum stress generated in the front and rear portions of Ie is such that the front portion has a strength equal to or higher than the rear portion, or close to this. The plate thickness distribution of the front region 11F is changed in the longitudinal direction.

That is, the side member thickness changing structure 50 is
As shown in FIG. 4, the plate thicknesses t1, t2, t3 ... t6 (t1 <t2 <t3 from the front end direction of the side member front region 11F).
<... <t6) A plurality of plate members 51a, 5 that change stepwise
51f is composed of a composite panel material 52 formed by welding the entire circumferences of 1b, 51c ... 51f, and the thickest plate material 5 is formed.
If is the reinforcing portion 11R.

The side member front area 11F
When the collision load F obliquely from the front is statically applied to the front end portion of the side member front region 11F as shown in FIG. 5, each virtual cross section Ia, Ib ...
Ie (see FIG. 3) generated axial force component stress (FY / A
(Y)) and moment component stress ({FX × (L−y)}
The maximum value of the sum of / Z (y) is the front portion ≈ the rear portion, and the upper limit value is the yield strength σ of the side member constituent material.
(Y).

Σ (y) = {FY / A (y)} + {FX × (L−y)} / Z (y) Equation 1 At this time, the upper limit value of the maximum stress due to the side member plate thickness change structure 50 Is set based on the yield strength of the material forming the side member 11 as described above, and as a result, as shown in FIG. 6, the distribution of the yield strength σ (y) for each of the plate members 51a, 51b, 51c ... 51f is obtained. To be

(Operation) According to the vehicle body front structure of the first embodiment having the above-described structure, when the static collision load F2 is applied obliquely from the front to the front end of the side member 11, as shown in FIG. As shown in FIG. 3, the imaginary cross sections Ia, Ib, ... I that are continuous in the longitudinal direction of the side member front region 11F.
The maximum value of the sum of the axial force component stress (FY / A (y)) and the moment component stress ({FX × (L−y)} / Z (y)) generated at e becomes the front portion ≈ the rear portion. Since the upper limit value is the yield strength σ (y) of the side member constituent material, the front end portion of the side member 11 which is the input point reaches the yield area of the material and undergoes plastic deformation during a collision which is a dynamic phenomenon. As a result, as a result of the collision from diagonally forward, the collision load F
When 2 is input, the side member front region 11F does not cause a simple bending mode at the base portion, which is apt to be seen in the conventional side member as shown in FIG.
As shown in FIG. 9B, the side member front region 11F
Induces a crush K from the front end which is the input point, and is deformed in a mode in which the crush K is continuously propagated backward, so that the collision energy can be reliably absorbed.

In this case, the side member front region 11
The component force of the collision load F2 from diagonally forward acts on F, which causes a shift from the base to the inside in the vehicle width direction as shown in FIG. The member front region 11F is to be axially crushed K.

Further, since the rear end portion of the side member front region 11F is a reinforcing portion 11R for mounting the power unit 30, special reinforcement is made by utilizing the rigidity characteristic of the reinforcing portion 11R. Since it is not necessary to apply it, rationalization and weight reduction of the structure of the side member 11 can be achieved.

Further, the side member plate thickness changing structure 50.
Is provided in the side member front region 11F, the collision load F1 from the front direction is axially input to the front end portion of the side member 11 as shown in FIG. Also in this case, as shown in FIG. 9A, similarly, the shaft crush K can be induced over the entire side member front region 11F to effectively absorb the collision energy.

Therefore, in the present embodiment, an axial crush K can be generated in the side member front region 11F with respect to the collision load F1 from the front direction and the collision load F2 from the oblique front, so that FIG. The absorption variation of the collision energy with respect to the input angle of the collision load F, which tends to be seen in the side member of the conventional structure as shown in a), is suppressed, and in the present embodiment, stable collision energy as shown in FIG. The absorption effect can be obtained.

By the way, in the present embodiment, the side member plate thickness changing structure 50 has a plurality of plate members 51a, 51b, 51c, ... 51 having different plate thicknesses t1, t2, t3 ... T6.
Since f is formed by using the composite panel material 52 joined so that the plate thickness thereof changes stepwise, the virtual cross sections Ia, Ib continuous in the longitudinal direction of the side member front region 11F.
... The maximum stress generated in Ie is approximately controlled so that the collapse K from the front end of the side member front region 11F can be induced without any trouble, and the side member front region 11F can be easily formed. You can

Further, since the side member plate thickness changing structure 50 has a cross sectional size changing structure in which the cross sectional size of the side member front region 11F is changed in the longitudinal direction, the collision load F is influenced by the side member 11. When input to the front end of the side member, it becomes easier to control the maximum stress that occurs in the virtual cross section that is continuous in the longitudinal direction of the side member front region, and it becomes easier to adjust the strength balance, so that the front side member at the time of collision can be controlled. The collapse K from the front end of the region 11F can be more reliably induced.

The plate members 51a, 51b, 51c ... 5
The number of 1f is not limited to this embodiment, and the number may be determined according to the required crushing characteristics of the side member front region 11F.

Further, the side member plate thickness changing structure 50 is
Although the maximum stress generated at the front and rear of the imaginary cross section of the side member front region 11F is set to be front ≈ rear, the front is not limited to this, that is, front ≧
The strength may be set to the rear part or a state close to this.

(Second Embodiment) FIG. 11 shows a second embodiment of the present invention. The same components as those of the first embodiment will be designated by the same reference numerals and overlapping description will be omitted.
Note that FIG. 11 is an enlarged cross-sectional view of the front region of the side member.

In the second embodiment, as shown in FIG. 11, the strength adjusting means is provided with a plurality of partition plates 61 at appropriate intervals in the longitudinal direction within the closed cross section of the side member front region 11F.
a, 61b, 61c ... 61e are arranged, and each partition plate 61
a, 61b ... 61e, plate thickness t1, t2 ... t5 (t1 <t
2 <... <t5) is configured as a partition plate thickness changing structure 60 in which the side member 11 is changed in the longitudinal direction.

That is, the partition plates 61a, 61b ... 61
e is a side member front region 11F having a closed cross-section structure
These partition plates 6 are fixed and integrated inside the
61e is arranged to increase the rigidity of the side member front region 11F, and the increase rate of the rigidity can be increased in accordance with the plate thicknesses t1, t2, ... T5.

At this time, the rigidity of the reinforcing portion 11R on which the power unit 30 (see FIG. 2) is mounted is determined by the partition plate 61.
It can be ensured by the plate thickness t5 of e, and in the second embodiment, the side member front region 11F.
The plate thickness t of the peripheral wall is constant over the entire section.

Therefore, in the vehicle body front structure of the second embodiment, when the collision load F is input to the front end portion of the side member 11, the maximum generated in the imaginary cross section continuous in the longitudinal direction of the side member front region 11F. Control of stress on each partition plate 6
1e, 61b ... 61e, which in turn facilitates the adjustment of the strength balance and can reliably induce the collapse K from the front end of the side member front region 11F at the time of a collision. It is possible to obtain the same effect as the form.

Further, in this embodiment, the plate thickness t of the front region 11F of the side member is constant over the entire section, but the plate thickness of the side member is changed stepwise as in the first embodiment. It can also be combined with the variable structure 50.

(Third Embodiment) FIGS. 12 and 13 show a third embodiment of the present invention, in which the same components as those in the first embodiment are designated by the same reference numerals and a duplicate description will be omitted.
12 is a schematic plan view showing the skeleton structure on the right side of the front part of the vehicle body, and FIG. 13 is a perspective view of the front region of the side member.

The vehicle body front structure of the third embodiment is shown in FIG.
2, the reinforcing portion 1 of the side member 11 as shown in FIG.
Side member front region 11F provided in the front portion from 1R
Are inclined outward in the vehicle width direction toward the front of the vehicle body.

In this embodiment, the side member front region 11F is provided with a side member plate thickness changing structure 50 as a strength adjusting means as in the first embodiment, and the side member plate thickness changing structure 50 is formed. The thickness is increasing and changing.

Therefore, in the vehicle body front structure of the third embodiment, the side member front region 11F is formed so as to be inclined outward in the vehicle width direction toward the front of the vehicle body. Therefore, the side member front region 11F can be continuously crushed from the tip even when the frontal collision occurs.

Further, as shown in FIG. 12, the front end portion of the side member 11 can be arranged further outward of the vehicle body by the side member front region 11F inclined outward in the vehicle width direction. The input support range can be expanded in the vehicle width direction.

That is, in the case where the side member 11 is formed straight as shown by the broken line in FIG. 12, even in the collision mode in which the side member 11 is not input, the solid line in FIG. The side member 11 of the present embodiment shown
Then, the component force component Fn of the collision load F is input to the side member front region 11F, and the collision energy can be absorbed well.

Further, the side member front region 11F
Is inclined outward from the reinforcing portion 11R on which the power unit 30 is mounted, in the vehicle width direction. Therefore, as shown in FIG.
Since the path C can be configured to be transmitted from 1R to the power unit 30 via the mount bracket 31 and further to the other reinforcing portion 11R and the other side member 11 via this power unit 30, the collision load F can be applied to the front of the vehicle body. It can be dispersed in a wide range of parts.

(Fourth Embodiment) FIGS. 14 to 16 show a fourth embodiment of the present invention, in which the same components as those in the above-mentioned embodiments are designated by the same reference numerals and a duplicate description will be omitted.
14 is a perspective view of the front region of the side member, FIG. 15 is an enlarged sectional view taken along the line BB in FIG. 14, and FIG. 16 is a stress distribution diagram showing the concept of strength adjusting means.

The vehicle body front structure of the fourth embodiment is shown in FIG.
As shown in FIG. 4, the strength adjusting means is configured as a sectional dimension changing structure 70 in which the sectional dimensions x and y of the side member front region 11F are changed in the longitudinal direction.

The cross-sectional dimension change structure 7 of this embodiment is also used.
0 indicates the side member front region 11F as shown in FIG.
The distribution of the plate thickness t is changed so as to taper, and the cross-sectional dimensions x and y and the plate thickness t are continuously changed.

In this embodiment, the side member 11 is entirely formed of an extruded material of a light alloy such as an aluminum alloy, and the cross-sectional dimensions x and y and the plate thickness t are changed in the side member front region 11F.

Also in this embodiment, when the collision load F is statically applied to the front end portion of the side member 11, the axial force component generated in each imaginary cross section continuous in the longitudinal direction of the side member front region 11F. The maximum value of the sum of the stress and the moment component stress (see the above formula 1) is constant in the longitudinal direction and is the yield strength of the material.

Therefore, the vehicle body front structure of this embodiment is
The side member front region 11F changes not only the plate thickness t but also the cross-sectional dimensions x and y while having the same function as that of the first embodiment. By changing the cross-sectional dimensions x and y in this way, From the viewpoint of material mechanics, it is possible to increase the sensitivity to the member cross-section constant as compared with the change in the plate thickness t.

Moreover, since the side member front region 11F is made of an extruded material capable of continuously changing the cross-sectional dimensions x and y and the plate thickness t in the longitudinal direction, the plate thickness can be easily adjusted, and Further structural rationalization and weight reduction can be achieved.

Further, in this embodiment, since the cross-sectional dimensions x and y and the plate thickness t are continuously changed, the stress distribution is substantially constant over the entire area of the side member front region 11F as shown in FIG. Has become.

The vehicle body front structure of the present invention has been described by taking the above-described embodiments as examples, but other embodiments can be adopted without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is an external perspective view of an automobile targeted by the present invention.

FIG. 2 is a schematic plan explanatory view showing a skeleton structure on the right side of the front portion of the vehicle body in the first embodiment of the invention.

FIG. 3 is a perspective view of a side member front region according to the first embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view taken along the line AA in FIG.

FIG. 5 is an explanatory view showing the strength adjusting means in the first embodiment of the present invention with an input form model (a) and a stress distribution diagram (b).

FIG. 6 is a stress distribution diagram showing the concept of strength adjusting means in the first embodiment of the present invention.

FIG. 7 is a schematic plan explanatory view on the right side of the front portion of the vehicle body showing an input form at the time of a frontal collision and an oblique frontal collision in the first embodiment of the present invention.

FIG. 8 is an explanatory view showing a deformation mode of a side member that is conventionally seen.

FIG. 9 is a frontal collision (a) according to the first embodiment of the present invention.
And an explanatory view showing a deformation mode of the side member at the time of an oblique frontal collision (b).

FIG. 10 is a graph comparing the relationship between the energy absorption amount and time at the time of a frontal collision and a diagonal frontal collision of the side member in the first embodiment of the present invention between the conventional (a) and the present embodiment (b).

FIG. 11 is an enlarged cross-sectional view of a side member front region in the second embodiment of the invention.

FIG. 12 is a schematic plan view showing the skeleton structure on the right side of the front part of the vehicle body in the third embodiment of the invention.

FIG. 13 is a perspective view of a side member front region according to a third embodiment of the present invention.

FIG. 14 is a perspective view of a side member front region in the fourth embodiment of the present invention.

FIG. 15 is an enlarged cross-sectional view taken along the line BB in FIG.

FIG. 16 is a stress distribution diagram showing the concept of strength adjusting means in the fourth embodiment of the present invention.

[Explanation of symbols]

10 car body FC front compartment 11 side members 11F Side member front area 11R reinforcement part 30 power units (vehicle unit parts) 50 Side member thickness change structure (strength adjusting means) 51a, 51b, 51c ... 51f Plate material 52 Composite panel material 60 Partition plate thickness change structure (strength adjusting means) 61a, 61b ... 61e Partition plate 70 Cross-sectional dimension change structure (strength adjusting means) Ia, Ib ... Ie virtual cross section

Claims (10)

[Claims] 1. A vehicle body front structure comprising reinforcing members for mounting vehicle unit parts on side members arranged in front and rear directions of a vehicle body on both left and right sides of a front compartment, the front portion of the side member being reinforced. In the front region of the side member, the strength adjusting means is provided so that the maximum stress generated in the front part and the rear part of the virtual cross section continuous in the longitudinal direction is such that the front part has a strength equal to or higher than the rear part or close to this. The front structure of the car body. 2. The vehicle body front structure according to claim 1, wherein the upper limit value of the maximum stress by the strength adjusting means is set on the basis of the yield strength of the material forming the side member. 3. The vehicle body front portion according to claim 1, wherein the strength adjusting means is a side member plate thickness changing structure in which the plate thickness distribution in the front region of the side member is changed in the longitudinal direction. Construction. 4. The side member plate thickness changing structure comprises a composite panel member in which a plurality of plate members having different plate thicknesses are joined so that the plate thicknesses thereof are changed stepwise, and the plate thickness changing direction is the longitudinal direction. The vehicle body front structure according to claim 3, wherein the vehicle front structure is configured as described above. 5. The strength adjusting means arranges a plurality of partition plates at appropriate intervals in the longitudinal direction within the closed cross section of the front region of the side member, and changes the plate thickness of each partition plate in the longitudinal direction of the side member. The vehicle body front structure according to claim 1 or 2, which is a partition plate thickness changing structure. 6. The vehicle body front portion according to claim 1, wherein the strength adjusting means is a cross-sectional dimension change structure in which the cross-sectional dimension of the side member front region is changed in the longitudinal direction. Construction. 7. The side member front region is formed by an extruded material whose extruded plate thickness and extruded cross-sectional dimension continuously change in the extruding direction, and the plate thickness or cross-sectional dimension of the side member front region is changed, or the plate thickness is changed. 3. The vehicle body front structure according to claim 1, wherein the strength adjusting means is configured by changing both of the cross sectional dimension and the cross sectional dimension. 8. The maximum stress is set by the strength adjusting means on the assumption that a diagonal input is statically applied to the front end portion of the side member, and the axial force generated in each virtual cross section continuous in the longitudinal direction of the front region of the side member. The vehicle body front structure according to claim 1, wherein a value calculated by considering both the component stress and the moment component stress is applied. 9. The front region of the side member of each of the left and right side members is formed straight in the front-rear direction of the vehicle body and arranged in parallel with each other. Body front structure. 10. The vehicle body according to claim 1, wherein the front regions of the left and right side members are formed so as to be inclined outward in the vehicle width direction toward the front of the vehicle body. Front structure.