CN102229348A - Front longitudinal beam and geometric energy absorbing control structure as well as automobile and method for providing geometric energy absorbing control structure - Google Patents

Abstract

The invention discloses a front longitudinal beam used for a geometric energy-absorbing control structure at the front of an automobile, comprising a front section module, a middle section module and a rear section module, wherein: the front section module extends obliquely forward and downward from the front end of the middle section module and is connected with the front section module The connection between the rear section module and the rear end of the middle section module; a vehicle front geometric energy-absorbing control structure including the front longitudinal beam and the vehicle; compared with the prior art, the present invention is compatible with the A-pillar The lap height of the engine compartment is higher than that of the traditional straight longitudinal beam, which releases the space under the engine compartment, is conducive to the overall layout of the engine compartment, and can provide a good impact energy absorption effect.

Description

Front side member, how much energy-absorbing control structures, automobiles and the method that how much energy-absorbing control structures are provided

Technical field

The present invention relates to the passive satety field of auto against, be specifically related to a kind of automotive front how much energy-absorbing control structure (GAC:Geometric Absorption Control) usefulness of head-on crash front side member, have how much energy-absorbing control structures, automobiles of this longeron and the method for how much energy-absorbing control structures be provided.

Background technology

Front side member is one of key structure of auto body.In collision process, crumple and flexural deformation by front side member can absorb most of collision energy, and as the bang path of impact force, disperse to transmit collision energy to rear structure.

The front rail structure of manned vehicle mostly is the straight beam formula at present.Fig. 1 has shown a kind of front rail structure layout of straight beam formula of routine.As shown in Figure 1, the auto against energy-absorbing control structure as prior art mainly comprises: be positioned at vehicle body bumper/spoiler 9 foremost; From bumper/spoiler 9 to the vehicle body rear extension and with bumper/spoiler 9 bonded assembly energy-absorbing boxes 8; The straight longeron 20 that extends back and be attached thereto from energy-absorbing box 8.Radiator bearer 10 vertically crosses energy-absorbing box 8 substantially, is used for supporting radiator.Energy-absorbing box 8 also with vertical overlap joint of front end of fore sub frame 6.The layout of this prior art also comprise usually be positioned at straight longeron top and with last A post 4 bonded assemblys on short beam 19, it is used for supporting engine hood etc.

When bumping, impact force from bumper/spoiler 9 be passed to backward energy-absorbing box 8, straight longeron 20, with straight longeron 20 bonded assembly dash shields 21 (Fig. 7).In addition, the small part impact force also can be passed to A post 4 and be passed to fore sub frame 6 by last short beam 19.When impact force hour, the energy-absorbing box can absorb whole or most of collision energies.When energy-absorbing box 8 is not enough to absorb all collision energies, the remainder of collision energy will be delivered to straight longeron 20 by energy-absorbing box 8.Thereby straight longeron 20 crumples and/or flexural deformation absorb all the other collision energies as much as possible, and is indeformable with maintenance crew module's especially operator's compartment complete sum.

Though the front side member of this straight beam formula and endergonic structure energy-absorbing in head-on crash is abundant, it is highly lower in the car load layout, as shown in Figure 1, within the altitude range of wheel 7, is in the middle and lower part of machinery space usually.Owing to be subjected to the restriction in dynamic assembly space, this straight longeron can't be designed to have roomy cross section usually, again often for fear of when turning to, interfering with wheel and front suspension leverage, need on straight longeron, pit 24 (Fig. 7) be set, this can cause the structure reduction, thereby is unfavorable for the stable crumple distortion of maintenance in collision.

The front side member of other type has also been proposed in the prior art, for example disclose a kind of " Z " shape front rail structure among the Chinese patent application No.200910191263.4, it comprises epimere, link to each other with the epimere rear portion descending section and the linkage section that is extended back by descending segment trailer.The improvements of this " Z " shape front rail structure are that mainly portion is provided with anterior brace panel, middle part brace panel and rear portion brace panel respectively before, during and after the epimere of front side member, and each brace panel is provided with convex tendon.This front side member does not have to solve the problem that proposes above yet.

China utility model patent ZL200820238454.2 has proposed a kind of segmentation welding formula front side member, and before, during and after this front side member is divided into three sections, adopt welding to form an integral body, have the material thickness that increases gradually to back segment from leading portion, stage casing; But this longeron totally remains the form of straight longeron in the vertical, also has the same problem of top described front side member.

Chinese patent ZL200810089273.2 discloses a kind of front energy-absorbing structure of vehicle frame, it comprises a crossbeam, two longerons, energy-absorbing box and brace panels, its center member is connected to longeron, be used for impact energy is passed to two longerons, longeron is the box-like beam of straight line (tubular beam), can face the same problem of top described front side member.

China utility model patent ZL200620115340.X has proposed a kind of automobile chassis frame, its improvements be the arranged outside at longeron have front-wheel after move position limiting structure, be used for limiting front-wheel after the amount of moving excessive.In this automobile chassis frame, longeron also is arranged in the machinery space bottom, also has the same problem of top described front side member.

In the disclosed a kind of automobile front structure of U.S. Patent Application Publication US2003/0141712A1, longeron also is arranged within the altitude range of wheel (Fig. 8 A and 8B).

Summary of the invention

The present invention proposes a kind of front side member that is used for how much energy-absorbing control structures of automotive front, this front side member comprises preceding root module, middle root module and back root module, before wherein said root module therefrom the front end of root module oblique before under extend and be attached thereto, described back root module is connected with the rear end of described middle root module, longitudinal cross-section from front side member, described back root module begins from the rear end of middle root module to become gradually greatly in the mode that forms " people " font layout with the back root module, and the described rear end of root module afterwards is used for being connected with the top of the following A post of vehicle occupant compartment.

Preferably, front side member integral body is arch.

Preferably, the angle that the axis of preceding root module and the axis of middle root module form is between 0～60 degree, and the angle that the axis of back root module and the axis of middle root module form is between-30～60 degree.More preferably, the angle that the axis of preceding root module and the axis of middle root module form is between 0～15 degree, and the angle that the axis of back root module and the axis of middle root module form is 0 degree.

Preferably, the front side member that preceding root module, middle root module and back root module are formed by two sections or three sections independently uniform cross section or varying cross-section duct beam be welded, perhaps form by adding reinforcement, reinforced rib or reduction groove by one section integral type arch tube beam.

The invention allows for how much energy-absorbing control structures of a kind of automotive front, comprise front bumper, from front bumper extend back and with bumper/spoiler bonded assembly energy-absorbing box, from the energy-absorbing box extend back and be attached thereto according to each the front side member and the last A post and the following A post of vehicle occupant compartment the aforementioned claim, the rear end of the back root module of wherein said front side member is connected to described A post down at the upper position place of the following A post of vehicle occupant compartment, make the installation site of described front side member be higher than vehicle front.

Preferably, described how much energy-absorbing control structures also comprise fore sub frame, and described energy-absorbing box, preceding root module, fore sub frame three form " people " font overlap joint.

Preferably, the rear end of back root module with vehicle occupant compartment on place, joint portion and the vehicle occupant compartment of A post and following A post A post and following A post formation " people " font overlap.

Preferably, the rear end upper surface of described back root module is smoothly transitted into the A post.

In addition, the present invention also provides a kind of automobile, and it comprises how much energy-absorbing control structures of aforesaid automotive front.

At last, the invention allows for a kind of method that how much energy-absorbing control structures of automotive front are provided, may further comprise the steps:

A kind of front side member is provided, and this front side member comprises preceding root module, middle root module and back root module, wherein said before root module therefrom the front end of root module extend down before oblique and be attached thereto, described back root module is connected with the rear end of described middle root module;

The front end of preceding root module is connected with the energy-absorbing box;

The rear end of back root module is connected to described A post down at the upper position place of the following A post of vehicle occupant compartment, makes the installation site of described front side member be higher than vehicle front.

The straight girder work that is different from present popular automobile engine nacelle, adopt a kind of and vehicle occupant compartment to have the arch front rail structure of higher overlap height according to GAC technology according to the present invention, it can absorb collision energy by distortion, and have stable crumple deformation pattern, possess good head-on crash performance; By improving overlap height, can obtain bigger machinery space space, help the layout of machinery space master layout and front suspension leverage.

Description of drawings

With reference to the description of exemplary embodiment of the present invention being done below in conjunction with accompanying drawing, the features and advantages of the present invention will be clearly, in the accompanying drawing:

Fig. 1 shows the front rail structure layout according to prior art;

Fig. 2 shows how much energy-absorbing control structures according to exemplary embodiment of the present invention;

Fig. 3 shows the structure according to the front side member of exemplary embodiment of the present invention;

Fig. 4 shows the transmission of impact force in how much energy-absorbing control structures of Fig. 2 when bumping;

Fig. 5 has shown the preferable configuration of a part of the front side member of Fig. 3;

Fig. 6 has shown according to the front side member of exemplary embodiment of the present invention and the layout of straight longeron on the automobile car according to prior art in the mode of oblique drawing and contrast; With

Fig. 7 has shown according to the front side member of exemplary embodiment of the present invention and the layout of straight longeron on the automobile car according to prior art in the mode of front elevation and contrast.

The specific embodiment

Exemplary embodiment of the present invention is described below with reference to the accompanying drawings.

Fig. 2 has shown how much energy-absorbing control structures according to exemplary embodiment of the present invention, and it mainly comprises with lower member: be positioned at vehicle body front bumper 9 foremost; From bumper/spoiler 9 to the vehicle body rear extension and with bumper/spoiler bonded assembly energy-absorbing box 8; From the longeron 100 that energy-absorbing box 8 extends back and is attached thereto, this longeron is connected to A post 5 under the upper position of A post 5 is connected to down.Longeron 100 comprises preceding root module 1 (leading portion beam), middle root module 2 (stage casing beam) and back root module 3 (back segment beam).Before the front end of root module 1 be connected with modules such as front bumper 9, energy-absorbing box 8, radiator rim 10, fore sub frames 6, and as the carrying structure of these modules.The front end of fore sub frame 6 also can adopt the right-angle structure of prior art as shown in Figure 1 and preceding root module 1 overlap joint of longeron 100, but preferably to tiltedly going up ground and preceding root module 1 overlap joint, thereby energy-absorbing box 8, preceding root module 1, fore sub frame 6 threes form " people " font joint.The rear end of preceding root module 1 is connected with the front end of middle root module 2.In the module (not shown) such as rear portion and front suspension bridge tower of root module 2 be connected, and as the carrying structure of modules such as front suspension, car bonnet.The rear end of middle root module 2 is connected with the front end of back root module 3.The front end of back root module 3 is also as the carrying structure of front suspension module (not shown).The rear portion of back root module is as the installation region of hood hinge support (not shown).The rear end of back root module 3 and last A post 4, following A post 5 overlap joints, preferably, the rear end surface of back root module 3 carries out the transition to A post 4 smoothly.

Fig. 2 has shown the structure according to the longeron 100 of exemplary embodiment of the present invention in further detail.As shown in Figure 2, the middle root module 2 of longeron 100 is level substantially, and preceding root module 1 is connected with middle root module 2, and therefrom root module 2 oblique preceding extensions down, the angle 11 that the axis 1a of preceding root module 1 and the axis 2a of middle root module 2 form is between 0～60 degree, preferably between 0～15 degree.In the joint of preceding root module 1 and middle root module 2, the preferred transition of adopting slyness.The angle 12 of the axis 3a of back root module 3 and the axis 2a of middle root module 2 is preferably 0 degree between-30～60 degree.In the joint of back root module 3 and middle root module 2, the preferred transition of also adopting slyness.Also preferably, the longitudinal cross-section of back root module 3 enlarges along fore-and-aft direction, so that middle root module 2 and back root module 3 also form " people " glyph construction.In the preferable configuration of the shown longeron 100 of Fig. 2, longeron 100 integral body are arch.

Before comprising the described front rail structure 100 of root module 1, middle root module 2 and back root module 3 can by two sections or three sections reality independently uniform cross section or varying cross-section duct beam be welded, also can by integral type arch uniform cross section or varying cross-section duct beam constitute but by add reinforcement, reinforced rib or reduction hole, the reduction groove forms aforesaid so-called three stage structure.

Root module 1, middle root module 2 and back root module 3 all are not enclosed beam structure or the sealed tube girder constructions that are welded by sheet metal component before described, preferably adopt the sealed tube girder construction, so that obtain the higher rigidity of structure.

The used sheet metal thickness of root module 1, middle root module 2 and back root module 3, material etc. can design according to actual needs before described, are out of shape energy-absorbing effect preferably so that reach.

Can design the length of described leading portion module 1 according to the machinery space total length, it is recommended between 300～800mm, preferably between 350～400mm.

Incidentally, the term of statement direction in this article " preceding, " back " all is the longitudinal directions along vehicle, with the headstock direction be before, with tailstock direction be after.In addition, form angles 11 or 12 with middle root module 2 about preceding root module 1 or back root module 3, present segment module 1 or back root module 3 with respect to middle root module 2 downwards the time angle for just, in the time of with respect to middle root module 2 upwards for negative.

Below in conjunction with Fig. 3 the operation of above-mentioned how much energy-absorbing control structures, the design and the advantage thereof of longeron are described.

As Figure 1-3, because therefrom root module 2 oblique preceding extensions down of the preceding root module 1 of longeron 100, energy-absorbing box 8, preceding root module 1, fore sub frame 6 threes form " people " font joint simultaneously, therefore, when the collision beginning, energy-absorbing box 8 transmits impact force 11 backward, can decompose in this " people " font joint and transmit along last power transmission passage 12, following power transmission passage 13.Last power transmission passage 12 transmits impact force backward by preceding root module 1, and following power transmission passage 13 transmits impact force backward by fore sub frame 6.Through this design, impact force is disperseed effectively.Present segment module 1, when middle root module 2 deforms in turn, impact force root module 3 is backward transmitted, and resolve into Path of Force Transfer 15, descend Path of Force Transfer 16 by means of " people " glyph construction of middle root module 2 and back root module 3, last Path of Force Transfer 15 is transmitted impact force backward through last A post 4, and following Path of Force Transfer 16 is transmitted A post 5 under the impact force process backward.Therefore under this Design Mode, can share the impact force of larger proportion except following A post 5, last A post 4 also can be born the impact force of significant proportion.Because last A post has been shared a part of impact force, the impact force that the A post is born reduces, and following A post is connected with floor, sill strip front end, so the impact that crew module's bottom section bears in collision is eased.

Owing to preceding root module 1 oblique preceding extension down thereby with impingement area leaning angle is arranged, for the last power transmission passage 12 of the joint that guarantees " people " font, power transmission passage 13 can be stablized and transmits impact force backward down, can design the angle (being respectively under the situation of form of straight lines at preceding root module, middle root module) of front-end module according to the crooked critical angle of straight beam.Known when being subjected to nonaxial collision power, deflection of beam critical angle formula is,

$\mathrm{\θ}=-0.0043{\left(\frac{L}{b}\right)}^3-0.122{\left(\frac{L}{b}\right)}^2+1.022\left(\frac{L}{b}\right)+17.5$

In the following formula, L is the length of beam, and b is the width of beam.

The width of the front side member cross-sectional plane of current most cars is greater than 100mm, so length 300～800mm of the preceding root module of recommending above 1, be under 8: 1 the situation in aspect ratio (L/b), before the crooked critical angle of root module 1 be about 16 degree, therefore before the recommendation at root module 1 and middle root module 2 formed angles of inclination 11 be below 15 degree.The inclination angle on tiltedly forward of the front end of fore sub frame also can be designed with reference to the method.

Under aforesaid " people " font joint layout, the rear end of root module 1 before maximum moment of flexure usually occurs in is promptly with the lap-joint of middle root module 1.For preventing stress concentration, therefore, also advise built-in reinforcement except being provided with the rounding off in the lap-joint of preceding root module 1 with middle root module 2.

During by conquassation, it is stable that the structure of middle root module 2 need keep in collision for the leading portion of present segment module 1 and subframe 6, so that the crumple energy-absorbing that root module 1 can be stable before making.For root module 2 in guaranteeing can bending deformation not take place when preceding root module 1 crumple, the present invention recommends the design according to root module 2 in the maximum load capacity formula school of rectangular tube beam.The maximum load capacity formula of known rectangular tube beam is:

$F_{\max }=t^{1.86}{b}^{0.14}(1+d/b){\left[\frac{k_{p}E}{(1-{\mathrm{\υ}}^2)\mathrm{\β}}\right]}^{0.43}{\mathrm{\σ}}_y^{0.57}$

In the following formula, t is a thickness, and b is a depth of section, and d is a section width.k _p, β is material mechanical parameters, and is relevant with t, b, d.Check through following formula, the average conquassation power that produces when the buckling loading of root module 2 is stablized conquassation greater than preceding root module 1 in making, and leave certain surplus (recommending the surplus more than 20%), the unstability flexing does not take place in root module 2 in guaranteeing thus.

Present segment module (leading portion beam) is when 1 crumple is finished, and middle root module 2 participates in the distortion energy-absorbing.Root module 2 adopts sealing rectangular tube beam to make in the recommendation, the sectional dimension of root module 1 before its sectional dimension is not less than.Equally as can be known according to above-mentioned maximum load capacity computing formula, adopt the Guan Liang of larger cross-section size to have higher ultimate bearing capacity, in the time of can making the front portion of middle root module (stage casing beam) 2 that the crumple distortion takes place, it is stable that its rear portion still can keep, and prevents distortion expansion backward too early.

Since with the leading portion module class seemingly, back root module 2, go up A post 4, A post 5 threes also constitute the connection of " people " font down, the overlap height of back root module 2 and A post is than traditional straight longeron height.Because the back root module is in machinery space and the crew module accepts the position, need reach higher structural stability, therefore, the longitudinal cross-section of back root module 3 enlarges along fore-and-aft direction as mentioned above, so that middle root module 2 and back root module 3 also form " people " glyph construction and form rounding off at overlapping part, thereby with the supreme A post of impact force stable delivery, following A post (Fig. 4,5).

A-pillar structure will bear on the vehicle body of the present invention, transmit a certain proportion of impact force owing to adopted, so the present invention recommends the A post to strengthen according to actual.

The present invention has following advantage with respect to prior art:

1. owing to formed the topology layout of " people " font according to how much energy-absorbing control structure front ends of present embodiment, root module 1 forms upper and lower power transmission passage with fore sub frame 6 promptly, impact force is disperseed effectively, alleviate the force-bearing situation of the single power transmission passage of initial time prior art employing, therefore the front end layout of this " people " font is more stable than single straight longeron.

2. also the single straight longeron than traditional is bigger to the absorption power of collision energy according to how much energy-absorbing control structure front end layouts of present embodiment.This is because the average bearing capacity of axial conquassation of beam is:

$F_a=8.604\frac{k}{n+1}{\left(0.15\right)}^{\mathrm{<figure-callout\; id="1"\; label="n\; C"\; filenames="HDA0000053082810000012.png,HDA0000053082810000032.png"\; state="\{\{state\}\}">n</figure-callout>}}{C}^{}{}^{1/3}{\mathrm{<figure-callout\; id="5"\; label="t"\; filenames="HDA0000053082810000011.png"\; state="\{\{state\}\}">t</figure-callout>}}^{5/3}$

In the following formula, k, n are the hardening Plastic parameter of material, and C is " (the long edge lengths of beam section+beam section width edge length)/2+ flange length ", and t is a beam panel beating thickness.

The subframe front end section width of existing car is all more than 20mm, therefore according to following formula, the extreme case that has only the arch longeron cross section length of side 1/5 for the subframe cross section length of side, the average conquassation load-carrying capacity of subframe front end is 3/5 of a preceding root module, according to the stressed rule of parallelogram, preceding root module and subframe front end are under 15 degree inclination angle situations, and the single straight girder work of the average bearing capacity ratio of the conquassation of preceding root module is larger about 60%.In other words, under equal crumple distance, front-end architecture of the present invention can absorb more collision energy.

Since the middle root module 2 of arch longeron 100 adopted section width to be not less than before the sealed tube beam of root module make, according to the maximum load capacity computing formula as can be known, adopt the Guan Liang of larger cross-section size to have higher ultimate bearing capacity, when the structure generation crumple therefore before the root module 2 is out of shape, middle root module can keep stable, has avoided the appearance of unstable distortion such as flexing.

4. the back root module 3 of arch longeron 100 and the overlap height of A post are than traditional straight longeron height, the A post is as a power transmission passage on can making full use of in collision, particularly in the collision bigger moment of later stage impact force, this structure can have been shared the impact force of time power transmission passage to a certain extent, and this acceleration/accel for the distortion of alleviating the crew module bottom, reduction crew module bottom is significant.By contrast, the straight longeron (see figure 7) of existing car is in the front-wheel inboard, the flow direction of main power is transmitted by the bottom, floor, the moderate finite deformation that in collision, causes the ground front edge of board easily, and, directly do not overlap, thereby cause impact force to be not easy to transmit backward by crew module's framework (upper and lower A post) with upper and lower A post because its rear end is overlapped on (see figure 7) on the dash shield, form the power concentration zones easily at the dash shield place, cause the intrusion amount of dash shield bigger.

5. how much energy-absorbing control structures according to present embodiment can reach machinery space structure weight-saving effect.According to Fig. 1, also need extra last short beam 19 to support car bonnet etc. in the prior art.For how much energy-absorbing control structures according to present embodiment, as Fig. 2, Fig. 5 and Fig. 6 as can be known, because the position of arch longeron 100 in machinery space is higher, its can be directly as the supporting construction of car bonnet, therefore adopted machinery space according to how much energy-absorbing control structures of present embodiment can save last short beam structure under the straight longeron pattern of tradition.

6. how much energy-absorbing control structures according to present embodiment also help machinery space general layout.Because arch longeron and following A post 5 tops overlap joint, preferably form the herringbones overlap joint with last A post 4, following A post 5, the layout of arch longeron 100 highly is higher than front-wheel, discharged the machinery space lower space, as shown in the figure, wherein Reference numeral 22 is represented the cross-sectional plane of the middle root module of arch longerons 100, the cross-sectional plane of the straight longeron 20 of Reference numeral 23 expression tradition; And the straight longeron of tradition has occupied the machinery space inner space because overlap height is lower, and Chang Yinwei avoid interfering and straight longeron done cut damage (pit 24 for example is set) with driving engine, chassis leverage and wheel, caused the reduction of longeron intensity.

Above described be preferred implementation of the present invention; but the present invention is not limited to such scheme; other any do not deviate from change, the modification done under spirit of the present invention and the principle, substitutes, combination, simplify; all should be considered as the substitute mode of equivalence, be included in protection scope of the present invention.

Claims (10)

1. front side member that is used for automotive front how much energy-absorbing control structures, this front side member comprises preceding root module, middle root module and back root module, before wherein said root module therefrom the front end of root module oblique before under extend and be attached thereto, described back root module is connected with the rear end of described middle root module, longitudinal cross-section from front side member, described back root module begins from the rear end of middle root module to become gradually greatly in the mode that forms " people " font layout with the back root module, and the described rear end of root module afterwards is used for being connected with the top of the following A post of vehicle occupant compartment.

2. according to the front side member of claim 1, wherein, described front side member integral body is arch.

3. according to the front side member of claim 1 or 2, wherein, the angle that the axis of preceding root module and the axis of middle root module form is between 0～60 degree, and the angle that the axis of back root module and the axis of middle root module form is between-30～60 degree.

4. according to the front side member of claim 1 or 2, wherein, before the front side member formed of root module, middle root module and back root module by two sections or three sections independently uniform cross section or varying cross-section duct beam be welded, perhaps form by adding reinforcement, reinforced rib or reduction groove by one section integral type arch tube beam.

5. how much energy-absorbing control structures of an automotive front, comprise front bumper, from front bumper extend back and with bumper/spoiler bonded assembly energy-absorbing box, from the energy-absorbing box extend back and be attached thereto according to each the front side member and the last A post and the following A post of vehicle occupant compartment the aforementioned claim, the rear end of the back root module of wherein said front side member is connected to described A post down at the upper position place of the following A post of vehicle occupant compartment, make the installation site of described front side member be higher than vehicle front.

6. according to how much energy-absorbing control structures of the automotive front of claim 5, wherein, described how much energy-absorbing control structures also comprise fore sub frame, and described energy-absorbing box, preceding root module, fore sub frame three form " people " font overlap joint.

7. according to how much energy-absorbing control structures of the automotive front of claim 5 or 6, wherein, the rear end of back root module with vehicle occupant compartment on place, joint portion and the vehicle occupant compartment of A post and following A post A post and following A post formation " people " font overlap.

8. according to how much energy-absorbing control structures of automotive front of claim 7, wherein, the rear end upper surface of described back root module is smoothly transitted into the described A post of going up.

9. automobile, wherein, this automobile comprises among the claim 6-8 each how much energy-absorbing control structures of automotive front.

10. method that automotive front how much energy-absorbing control structures are provided may further comprise the steps:

A kind of front side member is provided, and this front side member comprises preceding root module, middle root module and back root module, wherein said before root module therefrom the front end of root module extend down before oblique and be attached thereto, described back root module is connected with the rear end of described middle root module;

The front end of preceding root module is connected with the energy-absorbing box;

The rear end of back root module is connected to described A post down at the upper position place of the following A post of vehicle occupant compartment, makes the installation site of described front side member be higher than vehicle front.

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