JP2002114171A - Front body structure of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front body structure of an automobile capable of increasing the initial load of a longitudinal predetermined part of a front side frame, increasing the crushing initial load and the energy absorbing load in the initial period of the collision by forming a surface-treated part capable of being ruptured with low distortion without increasing a weight and the assembling man- hour, preventing the increase of deceleration at the end half of the crushing of the collided body by the buckling of the front side frame and the enlargement of the crush space, and reducing the load applied to an occupant. SOLUTION: In this front body structure of an automobile provided with a left and right pair of metallic front side frames 11, 11, the surface-treated parts 31, 31 capable of increasing the initial load and being ruptured with low distortion are formed on the longitudinal predetermined parts of the front side frames 11, 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body structure having a pair of left and right metal front side frames, and more particularly, to a vehicle front structure capable of reducing the deceleration acting on an occupant in a frontal collision. Related to body structure.

[0002]

2. Description of the Related Art Conventionally, as a vehicle body structure of a front part of the above-mentioned example, there is one described in, for example, JP-A-2000-53022. That is, as shown in FIGS. 10 and 11, a pair of left and right front side frames 91, 91 extending in the front-rear direction at the front portion of the vehicle body are provided. At normal time, the bumper reinforcement 93 and the auxiliary beams 92, 92 are attached.
Spacings 94, 94 are formed between the front end.

According to the conventional structure, the collision load is applied to the bumper reinforcement 93 during a frontal collision of the vehicle.
To the front side frames 91, 91 via
In the early stage of the collision, the front side frames 91, 91
(The vicinity of the joint with the bumper reinforcement 93) starts to be deformed and a relatively large deformation load is started, and the vehicle body deceleration rises sharply.

[0004] Due to the compression deformation of the front side frames 91, 91, the gaps 94, 94 are eliminated, and the input load from the bumper reinforcement 93 is transmitted to the sub beams 92, 92 extending obliquely. When the side beams 91, 91 receive side loads from the sub-beams 92, they are bent inward in the vehicle width direction as shown in FIG. 11, and the vehicle body deceleration is reduced.

In view of the above, the present invention is designed to greatly reduce the occupant deceleration by setting the seat belt elongation to reach a peak in the region where the vehicle body deceleration rapidly decreases.

However, the above-described conventional structure has the following problems. That is, the auxiliary beams 92, 92 need to bend the front side frame 91 as a vehicle body rigidity member, and therefore are constituted by a strength member having strength. Since this additional member (the auxiliary beam 92) needs to be added, the weight is reduced. However, there has been a problem in that the number of assembly steps increases.

[0007]

SUMMARY OF THE INVENTION The present invention increases the initial load on a predetermined portion of the front side frame in the front-rear direction,
By forming a surface treatment part that can be broken with low distortion,
The above-mentioned surface treatment increases the initial crushing load and the energy absorption load at the initial stage of collision without increasing the weight and the number of assembly steps, and furthermore, the buckling of the front side frame and the buckling of the front side frame after the fracture due to the low distortion of the surface treatment. It is an object of the present invention to provide a front body structure of an automobile capable of preventing an increase in deceleration in the latter half of a collision body collapse due to an increase in a crash space and reducing a load value applied to an occupant.

[0008]

A vehicle front body structure according to the present invention is a vehicle front body structure having a pair of left and right metal front side frames, wherein the front side frame has a predetermined longitudinal direction. The part is formed with a surface-treated part capable of increasing the initial load and breaking with low distortion. The surface treatment unit having the above configuration can be set as a quenching treatment unit (surface hardening treatment unit) by heat treatment or a shot peening treatment unit as a surface hardening treatment.

[0009] According to the above structure, the above-mentioned surface treatment portion increases the initial load in the front-rear direction of the front side frame and has a metal structure that can be broken with low distortion, so that the weight and the number of assembling steps are increased. Without any inconvenience, at the time of a frontal collision of the vehicle, the surface treatment portion of the front side frame does not break to a predetermined load, and the surface treatment portion can increase the initial crushing load and the energy absorption load at the beginning of the collision, and After the fracture due to the low distortion of the processing unit, the buckling of the front side frame and the expansion of the crash space (making the subsequent deformation easier by the fracture) prevent the deceleration in the latter half of the crashing vehicle body from increasing. Thus, the load value applied to the occupant can be reduced.

In one embodiment of the present invention, the surface treatment is set in a quenching section for a steel front side frame. According to the above configuration,
By quenching treatment (heat treatment), predetermined characteristics (high initial load,
In addition, it is possible to easily form a surface-treated portion having characteristics of breaking at low strain).

In one embodiment of the present invention, the surface treatment portion of the front side frame is provided between the engine support portion and the dash panel in the front-rear direction of the front side frame. According to the configuration described above, the initial load can be increased by surface-treating the low strength portion of the front side frame.

In one embodiment of the present invention, a perimeter frame is provided below the front side frame, and a predetermined portion in the front-rear direction of the perimeter frame includes:
A surface-treated portion that can be broken with a high initial load and low strain is formed.

According to the above construction, the perimeter frame supporting the engine and the front suspension is also provided with a surface treatment portion, and this perimeter frame also breaks and buckles with low distortion, so that the front side frame has the desired characteristics. Can be secured.

In one embodiment of the present invention, the surface treatment section of the perimeter frame is provided between the engine support section and the dash panel in the front-rear direction of the perimeter frame.

According to the above configuration, the surface treatment section on the front side frame side and the surface treatment section on the perimeter frame side are set at the same location or substantially the same location. Both are broken at substantially the same position, and the deformation behavior in the latter half of the collapse is less restricted, and the front side frame and the perimeter frame are easily deformed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawings show the front body structure of the automobile. In FIGS. 1 to 5, a pair of left and right front side frames 11 and 11 made of steel plates are provided extending in the front-rear direction of the vehicle. The floor frames 12 are integrally formed.

The above-mentioned front side frames 11, 11
At the front end of is provided a joining flange portion 13,
At the rear end, connecting members 15, 15 having connecting flange portions 14, 14 are provided, and these connecting flange portions 13, 1 are provided.
4 by connecting and fixing the front side frame 1
The connecting members 15, 15 are attached to the front ends of the connecting members 1, 11. A bumper reinforcement 16 extending in the vehicle width direction is stretched between the pair of left and right connecting members 15.

Here, both the bumper reinforcement 16 and the front side frame 11 are strength members having a closed cross-section structure. As shown in FIGS. 2 and 3, above the rear portion of the front side frame 11,
A dash lower panel 17 extending in the vehicle width direction is provided,
A tire house 18, a suspension tower 19, and a wheel apron reinforcement 20 are provided on the outer side of the front side frame 11, and a front part of the dash lower panel 17 is set in the engine room 21 and a dash lower panel 17 is provided. The rear is cabin 2
It is set to 2.

Further, the above-described front side frame 11
A steel plate perimeter frame 24 supporting the engine 23 (see FIG. 2) and the front suspension
(perimeter frame, frame type frame).

The perimeter frame 24 is shown in FIGS.
As shown in the figure, a front member 25 extending in the vehicle width direction between the front portions of the front side frames 11, 11 and a rear member 26 extending in the vehicle width direction between the front side frames 11, 11 at a position near the dash lower panel 17.
And a right-side member 27 extending substantially in the front-rear direction of the vehicle below the right front side frame 11 and a left-side member 28 extending substantially in the front-rear direction of the vehicle below the left front side frame 11 are integrated into a substantially cross-girder shape. It is a frame type frame formed.

The right and left members 27 and 28 of the perimeter frame 24 are provided with mounting portions 29, 29, 30, and 30, respectively, and the front mounting portions 29 and 29 are arranged in the vertical direction. The rear mounting portions 30, 30 are attached to a dash lower reinforcement or a torque box on the vehicle body side.

By the way, a part of the above-mentioned front side frames 11, 11 as a predetermined part in the front-rear direction is hardened as a surface treatment part (surface hardening part) capable of increasing an intended load and breaking with low distortion. Processing units 31, 31 (note that
(Shown by hatching for convenience of illustration) are formed so as to face each other on the left and right front side frames 11 and 11.

The quenching portion 31 is formed between the engine support portion (see FIG. 2 where the engine mount 32 is mounted) and the dash lower panel 17 in the front-rear direction of the front side frame 11. The quenching unit 31 is formed at a predetermined width over the entire front side frame 11 in the vertical direction.

More specifically, the above-described quenching processing section 31
As shown in the bottom view of FIG. 5, the front side frame 11 is set to a thin portion so as not to interfere with the steering of the front wheels 33.

Similarly, a part of the perimeter frame 24 as a predetermined part in the front-rear direction of the right side member 27 and the left side member 28 is also provided with a surface treatment portion (surface Hardening processing sections 34, 34 (shown by hatching for the sake of illustration) serving as hardening processing sections) are formed so as to be opposed by left and right members 27, 28.

The quenching section 34 on the side of the perimeter frame 24 is also located between the engine support section and the dash lower panel 17 in the front-rear direction of the perimeter frame 24, similarly to the quenching section 31 of the front side frame 11 described above. The quenching unit 3 is set
Reference numeral 4 denotes a predetermined width, which is formed over the entirety of the members 27 and 28 in the vertical direction. Further, the quenching processing unit 31 on the front side frame 11 side and the quenching processing unit 34 on the perimeter frame 24 side are formed so as to be substantially opposed in the vertical direction.

The above-described quenching units 31 and 34 are provided with a front side frame 11 and a perimeter frame 24.
The right and left members 27 and 28 are formed by a partial quenching process. For example, the quenching width in the vehicle longitudinal direction is about 40 to 50 mm, and the breaking strain is about 10%.

By forming the quenching sections 31 and 34, the strength of predetermined portions of the front side frame 11 and the perimeter frame 24 can be increased, and the initial load at the time of a vehicle crash can be increased. ,
Since the above-described quenching units 31 and 34 break with low distortion, the front side frame 11 and the perimeter frame 24 can be largely buckled.

FIG. 7 is a diagram showing a comparison between the material properties of the steel sheet material subjected to the quenching treatment and the ordinary steel sheet material not subjected to the quenching treatment. The distortion is plotted on the horizontal axis and the stress is plotted on the vertical axis. I have.

As is apparent from the figure, the ordinary steel sheet indicated by the dotted line a has a small stress and the time required for material breakage is relatively long, whereas the steel sheet material subjected to the quenching treatment indicated by the solid line b is The initial stress is high and the strength is improved.
It can withstand a heavy load in the event of a collision and the time required for material breakage is relatively short. The front side frame 11 and the perimeter frame 24 on which the above-described quenching units 31 and 34 are formed have the material characteristics shown by the solid line b in FIG.

The operation of the front body structure of the automobile constructed as described above will be described in detail below. In the load characteristic diagram shown in FIG. 8, when a frontal collision of the vehicle occurs at time t0, a collision load is input to the front side frame 11 and the perimeter frame 24 via the bumper reinforcement 16 and the like. 24 is a quenching unit 3
Since the initial load is increased by 1, 34, the characteristic c of this embodiment can withstand a high load F1 as shown by the solid line with respect to the conventional characteristic d having no quenched portion. Accordingly, the amount of energy absorption can be increased.

At time t1 in FIG. 8, the quenching processing units 31, 34
Is broken by low strain, the front side frame 11
The perimeter frame 24 greatly buckles as shown by phantom lines in FIGS. 3 to 6, and the load acting on the vehicle body (corresponding to the vehicle body deceleration) decreases from time t1 to time t2,
Prevents an increase in deceleration in the latter half of the crash of the vehicle. In FIG. 8, the cross-sectional area between the horizontal axis and the characteristic c is the energy absorption.

In FIG. 9, the horizontal axis represents time, and the vertical axis represents the deceleration (so-called occupant G) applied to the occupant. 31,
FIG. 7 shows a comparison with a characteristic n of this embodiment having a value of 34;

The occupant is restrained by the seat belt, and in the case of this embodiment having the quenching units 31 and 34, the seat belt is tensioned earlier due to the increased initial load, and the characteristic n at the beginning of the collision is increased. Rises faster than the conventional characteristic m, but the front side frame 11 and the perimeter frame 2
The buckling of 4 prevents the deceleration from increasing in the latter half of the crash of the colliding body, and reduces the load applied to the occupant. m can be significantly reduced by the predetermined G shown in FIG.

As described above, the front body structure of the vehicle according to the above-described embodiment includes a pair of left and right metal front side frames 1.
As shown in the characteristic diagram of FIG. 7, a predetermined portion as a predetermined portion in the front-rear direction of the front side frames 11, 11 is a front body structure of an automobile provided with In addition, a surface treatment part (see quenching treatment part 31) which can be broken with low distortion is formed. According to the above configuration, the front side frames 11, 11 have an increased initial load in the front-rear direction in the surface treatment section (see the quenching section 31), and have a metal structure that can be broken with low distortion. Also, without causing any increase in the number of assembling steps, the surface treatment sections (see the quenching section 31) of the front side frames 11, 11 do not break to a predetermined load (see F1 in FIG. 8) at the time of a frontal collision of the vehicle. , The surface treatment section
(See the quenching section 31) can increase the initial collapse load and the energy absorption load at the initial stage of the collision, and after the surface treatment section (see the quenching section 31) is broken by low distortion, the front side frames 11, 11 Buckling and the expansion of the crash space (the subsequent deformation is facilitated by breaking), preventing an increase in deceleration in the second half of the crash of the colliding body, and reducing the load value applied to the occupant. it can.

The above-mentioned surface treatment is performed by quenching processing parts 31 and 3 for the front side frames 11 and 11 made of steel.
Since it is set to 1, the specified characteristics by quenching treatment (heat treatment)
A surface-treated portion (having a high initial load and breaking at low strain) can be easily formed.

Further, the front side frame 1
The quenching sections 31, 31 of the front side frame 11, 11
It is provided between the dash panel (see the dash lower panel 17) and the dash panel (see the mounting portion of the engine mount 32 in FIG. 2). According to this configuration, the initial load can be increased by quenching the low strength portions of the front side frames 11, 11.

Furthermore, the front side frame 1
A perimeter frame 24 is provided at the lower part of the first and the eleventh, and a part of the perimeter frame 24 as a predetermined part in the front-rear direction is provided with a surface treatment part capable of increasing the initial load and breaking with a low distortion (see the quenching part 34). Is formed.

According to this configuration, the perimeter frame 2 supporting the engine 23 and the front suspension
4, a surface treatment portion (see the quenching treatment portion 34) is also formed, and the perimeter frame 24 also breaks and buckles with low distortion, so that the desired properties of the front side frame 11 can be secured.

The surface treatment section (see the quenching section 34) of the perimeter frame 24 is provided between the engine support section and the dash panel (see the dash lower panel 17) in the front-rear direction of the perimeter frame 24. is there.

According to this configuration, the quenching section 31 on the front side frame 11 side and the perimeter frame 24
Since the quenching part 34 on the side is set at the same location or substantially the same location, at the time of collision, both the front side frame 11 and the perimeter frame 24 are broken at substantially the same location, and the deformation behavior in the latter half of the collapse There is little constraint, and the front side frame 11 and the perimeter frame 24 can be easily deformed.

In the correspondence between the configuration of the present invention and the above-described embodiment, the metal front side frame of the present invention corresponds to the copper plate front side frame 11 of the embodiment, and likewise to the front side frame. The surface treatment unit corresponds to the quenching treatment unit 31, the surface treatment unit for the perimeter frame corresponds to the quenching treatment unit 34, and the dash panel corresponds to the dash lower panel 17. However, the present invention is not limited only to the configuration of the embodiment.

For example, the surface treatment section may be another surface treatment section (such as a shot peening treatment section) which increases the initial load and secures a characteristic of breaking with low distortion. Quenching unit 3
4 may be set at a position in the vicinity of the mount portion 30. Further, if necessary, the front side frame 1 may be provided.
1. The quenching units 31 and 34 may be formed at a plurality of locations on the perimeter frame 24 in the vehicle longitudinal direction.

[0044]

According to the present invention, a surface treatment portion capable of increasing the initial load and breaking with low distortion is formed at a predetermined portion in the front-rear direction of the front side frame, so that the weight and the number of assembling steps are increased. Without the surface treatment, the initial crushing load and the energy absorption load at the initial stage of collision are increased by the surface treatment, and after the fracture due to the low distortion of the surface treatment, the crushing of the collision body is caused by the buckling of the front side frame and the expansion of the crash space. Thus, there is an effect that it is possible to prevent an increase in deceleration in the vehicle and reduce the load value biased to the occupant.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a front body structure of an automobile according to the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a partial perspective view showing a state before and after the collision of the front side frame.

FIG. 4 is a side view of a main part of FIG. 3;

FIG. 5 is a bottom view showing a state before and after the collision of the front side frame.

FIG. 6 is a perspective view showing a state before and after the collision of the perimeter frame.

FIG. 7 is an explanatory diagram showing a difference in material properties depending on the presence or absence of a surface treatment.

FIG. 8 is a load characteristic diagram.

FIG. 9 is a characteristic diagram showing a change in deceleration applied to an occupant.

FIG. 10 is a plan view showing a front body structure of a conventional automobile.

FIG. 11 is a plan view showing a state at the time of a collision of the conventional structure.

[Explanation of symbols]

 11: Front side frame 17: Dash lower panel 24: Perimeter frame 31, 34: Quenching part (surface treatment part)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akiko Nakamoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima F-term (reference) in Mazda Co., Ltd. 3D003 AA01 AA04 AA05 BB01 CA05 CA09 CA53 CA58 CA60 DA03 DA29

Claims (5)

[Claims] 1. A front body structure of an automobile having a pair of left and right metal front side frames, wherein a predetermined portion in the front-rear direction of the front side frame is increased in initial load and fractured with low distortion. The front body structure of an automobile on which a surface treatment part to be obtained is formed. 2. The front body structure of an automobile according to claim 1, wherein said surface treatment is set in a quenching section for a steel front side frame. 3. The front side frame has a surface treatment portion provided between an engine support portion and a dash panel in a front-rear direction of the front side frame.
Or the front body structure of the vehicle according to 2. 4. A perimeter frame is provided at a lower portion of the front side frame, and a predetermined portion in the front-rear direction of the perimeter frame is formed with a surface treatment portion capable of increasing initial load and breaking with low distortion. 4. The front body structure of an automobile according to claim 1, 2, or 3. 5. The front body structure of an automobile according to claim 4, wherein the surface treatment portion of the perimeter frame is provided between the engine support portion and the dash panel in the front-rear direction of the perimeter frame.