JP7576508B2 - Front body structure - Google Patents

Description

The present invention relates to a vehicle front body structure.

Conventionally, there is known a technique for manufacturing a short front side frame using a mold for a long front side frame (for example, Patent Document 1). In such a technique, a stiffener (reinforcing plate) is attached to either the long or short front side frame, thereby reducing the number of molds required to manufacture the front side frame.

Patent No. 4783761

In such conventional vehicle front body structures, no consideration was given to which point would reliably become the bending point when a load is input from the front to the front side frame, leaving room for further improvement.
An object of the present invention is to provide a vehicle body front structure that can reliably cause deformation by means of weak portions to increase the amount of impact energy absorbed.

The vehicle front body structure of the present invention includes a front side frame extending in the vehicle longitudinal direction and having an upper ridgeline and a lower ridgeline , an upper stiffener formed with a substantially L-shaped cross section overlapping the upper ridgeline and arranged along the longitudinal direction, a lower stiffener formed with a substantially L-shaped cross section overlapping the lower ridgeline with a gap between the upper stiffener and the lower stiffener and arranged along the longitudinal direction, and a bulkhead overlapping the upper stiffener and the lower stiffener . The upper stiffener has a tip end of an upper ridgeline side portion extending in the vehicle longitudinal direction across the bulkhead, the lower stiffener has a tip end of a lower ridgeline side portion extending in the vehicle longitudinal direction across the bulkhead, the tip end of the lower ridgeline side portion extending in the front-rear direction beyond the tip end of the upper ridgeline side portion of the upper stiffener, and the front side frame has a weak portion formed in the vicinity of the bulkhead.

The present invention provides a vehicle front body structure that can reliably cause deformation through weak parts, thereby increasing the amount of impact energy absorbed.

1 is a plan view showing a state in which front side frames are arranged on both the left and right sides of a power chamber in a vehicle front body structure according to an embodiment of the present invention. FIG. 2 is a perspective view seen from the direction of the arrow II in FIG. 1 , illustrating the configuration of the left front side frame having a U-shaped stiffener in the vehicle front body structure of the first embodiment with a back plate removed. FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2, illustrating the configuration of a left front side frame in the vehicle front body structure of the first embodiment. FIG. 2 is a plan view of a left front side frame seen from above in the vehicle body front structure of the first embodiment, illustrating a deformation mode indicated by a two-dot chain line. FIG. 11 is a side view illustrating the configuration of a left front side frame having a substantially L-shaped stiffener in a vehicle body front structure of embodiment 2. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5, illustrating the configuration of the left front side frame in the vehicle front body structure of the second embodiment. 11 is a perspective view showing a state in which a back plate is removed from a left front side frame in the vehicle front body structure of the second embodiment. FIG. 8 is a cross-sectional view of the left front side frame of the vehicle front body structure of the second embodiment taken along line VIII-VIII in FIG. 7 . FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 1, illustrating the configuration of a left front side frame in the vehicle front body structure of the second embodiment. 1 is a plan view showing how the position of the front bumper can be set forward or rearward by changing the length of the bumper beam extension in the vehicle front body structure of the embodiment. FIG.

EMBODIMENT 1

The first embodiment of the present invention will be described below with reference to the drawings as appropriate. Identical components will be given the same reference numerals, and duplicate descriptions will be omitted. When describing directions, unless otherwise specified, they will basically be described based on front/rear, left/right, or up/down as seen by the driver. In addition, the "vehicle width direction" is synonymous with the "left/right direction."

1, a power chamber E for accommodating a power source such as an engine or a motor (not shown) is formed in a front portion 11 of a vehicle 10. A pair of left and right front side frames 1, 1 are provided on the left and right sides of the power chamber E so as to extend in the fore-and-aft direction of the vehicle.
The left and right front side frames 1, 1 have substantially symmetrical shapes, and therefore, in this embodiment, the left front side frame 1 will be mainly described and a description of the right front side frame 1 will be omitted.

A bumper joint plate 3 for mounting a front bumper 30 is fixed to the front end 1a of the front side frame 1. A front end 2a extending downward and forward from the upper member 2 (see FIG. 9) is fixed to the bumper joint plate 3. The front end 1a of the front side frame 1 is arranged inward in the vehicle width direction of the front end 2a, aligned in the vehicle fore-and-aft direction.

As shown in FIG. 1, a bumper beam assembly 31 is attached to the front end portion 1 a of the front side frame 1 .
The bumper beam assembly 31 includes a bumper beam extension 4 having a bumper joining plate 3, and a front bumper 30 connected to a pair of left and right bumper beam extensions 4, 4, respectively, and extending in the vehicle width direction.

The front bumper 30 is connected to each front side frame 1 via a pair of left and right bumper beam extensions 4, 4 and bumper joining plates 3, 3.
Further, rear end portions 1i of the front side frames 1 are connected to a dash lower panel 5. The dash lower panel 5 is disposed to separate the power chamber E from the vehicle interior R. The front side frames 1 are extended such that the rear end portions 1i are lowered toward the rear in accordance with the shape of the inclined surface of the dash lower panel 5.

As shown in Fig. 2, the front side frame 1 has an inner wall surface 1b facing the power chamber E on the inner side in the vehicle width direction, two upper and lower ridge lines 1c, 1d (see Fig. 3) provided along the longitudinal direction of the upper and lower edges of the inner wall surface 1b, and an upper wall surface 1e and a lower wall surface 1f connected approximately perpendicularly to each other with the ridge lines 1c, 1d in between. Note that Fig. 2 does not show a back plate 15 (see Fig. 3).
The front side frame 1 has folded flanges 1g, 1h at a rear portion thereof, which are connected to the upper wall surface 1e and the lower wall surface 1f approximately perpendicularly, respectively. The cross-sectional shape of the rear portion of the front side frame 1 having the folded flanges 1g, 1h is configured to be approximately hat-shaped.

The front side frame 1 is provided with a stiffener 16 that overlaps the two ridges 1c, 1d and runs along the longitudinal direction, and a bulkhead 17 that is further overlapped on the outside of the stiffener 16. As shown in FIG. 3, the stiffener 16 is formed with a cross section that is roughly U-shaped with the upper and lower edges 16b, 16c roughly perpendicular to the bottom surface 16a. The upper and lower ridges 16e, 16f of the stiffener 16 are positioned overlapping the inside of the ridges 1c, 1d of the front side frame 1.

2, the bulkhead 17 has a first bulkhead 8 provided at an engine fastening portion 50 of the front side frame 1, and a second bulkhead 9 provided at a subframe fastening portion 60 disposed rearward of the engine fastening portion 50. The first bulkhead 8 and the second bulkhead 9 are so-called partition walls, and divide the internal space of the front side frame 1 in the front-rear direction.
The stiffener 16 extends in the front-rear direction of the vehicle, straddling the first bulkhead 8 and the second bulkhead 9 .

The front side frame 1 has, successively from the front, a front weak portion 40, an intermediate weak portion 42, and a rear weak portion 45 which constitute the weak portion 20. The front weak portion 40 is provided in the vicinity of the tip end 16d of the stiffener 16.
As shown in FIG. 4, the front weakened portion 40 is formed with a first bending point 40a that is bent in the vehicle width direction of the front side frame 1 to form an outer edge that is roughly V-shaped in top view.
Further, the front side frame 1 is provided with a middle weak portion 42 and a rear weak portion 45 near the first bulkhead 8 and the second bulkhead 9, respectively.
The intermediate weak portion 42 has a second bend point 42b that makes the inner edge of the front side frame 1 roughly V-shaped in top view. The intermediate weak portion 42 forms a first bolt insertion hole 41 that opens in the upper surface of the front side frame 1.

The rear weakened portion 45 has a second bolt insertion hole 44 that opens on the lower surface (see FIG. 2 ). Further, the rear weakened portion 45 is formed with a third bending point 45a that makes the outer edge of the front side frame 1 roughly V-shaped when viewed from above.
By arranging the front side frames 1 successively rearward at predetermined intervals from the front of the vehicle, bending points are provided that bend in a zigzag pattern in the horizontal direction when a load is input from the front of the vehicle.

Furthermore, as shown in FIG. 2, the first bulkhead 8 has a first nut 51, and the second bulkhead 9 has a second nut 52. The first nut 51 of the first bulkhead 8 faces the first bolt insertion hole 41, and the second nut 52 of the second bulkhead 9 faces the second bolt insertion hole 44.

As shown by the two-dot chain lines in FIG. 4, the front side frame 1 is bent at the front weak portion 40, the middle weak portion 42 and the rear weak portion 45 due to the load input from the front.
In other words, the front side frame 1 is bent alternately in the horizontal direction, with a first bend point 40a having a narrow constriction with a roughly L-shaped side edge, a second bend point 42a located in the vicinity of the engine fastening portion, and a third bend point 45a located in the vicinity of the sub-frame fastening portion being bent alternately inward or outward in the fore-and-aft direction of the vehicle.
Therefore, bending of the front side frame 1 occurs starting from the front weak portion 40, the intermediate weak portion 42, and the rear weak portion 45, which are provided spaced apart in the front-rear direction. This reliably increases the amount of impact energy absorbed.

EMBODIMENT 2

5 to 10 show a vehicle body front structure according to a second embodiment of the present invention. Note that parts that are the same as or equivalent to those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted.
The second embodiment differs from the first embodiment in that, instead of the stiffener 16 having a U-shaped cross section of the first embodiment, a plurality of stiffeners having an L-shaped cross section are provided.
That is, as shown in Fig. 5, an upper front stiffener 26, an upper rear stiffener 27, and a lower stiffener 28 are provided along the longitudinal direction on two ridgelines 1c, 1d of the front side frame 1. The upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are each formed with a substantially L-shaped cross section with the vertical wall surface and the horizontal wall surface being substantially perpendicular to each other. The upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are members corresponding to the stiffener 16 of the first embodiment. The upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are each formed to have a narrower vertical dimension than the stiffener 16.
Furthermore, a gap 29 is provided between the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28, forming a space spaced a predetermined distance apart. The gap 29 is formed in a spatial shape that fits each stiffener 16 and stiffeners 26 to 28, etc., so that it can be changed to the U-shaped stiffener 16 of embodiment 1 or the L-shaped stiffener 26 of embodiment 2, etc.

On the front side frame 1, the upper front stiffener 26, the upper rear stiffener 27 and the lower stiffener 28 are overlapped so that their ridges 26e, 27e, 28f run along the ridges 1c and 1d, respectively.
The first bulkhead 8 and the second bulkhead 18 are overlapped and spaced apart in the front-rear direction on the outer sides in the vehicle width direction of the upper front stiffener 26, the upper rear stiffener 27 and the lower stiffener 28. The three bulkheads are then joined together with the front side frame 1 (see FIG. 6).
The first bulkhead 8 is disposed so as to straddle the upper front stiffener 26 and the lower stiffener 28. The upper and lower edges and the inner edge in the vehicle width direction of the first bulkhead 8 are joined together with the upper front stiffener 26, the lower stiffener 28 and the front side frame 1 in three pieces.
The second bulkhead 18 is disposed so as to straddle the upper rear stiffener 27 and the lower stiffener 28. The upper and lower edges and the inner edge in the vehicle width direction of the second bulkhead 18 are joined together with the upper rear stiffener 27 , the lower stiffener 28 and the front side frame 1 in three pieces.
Of these, the upper front stiffener 26 and the upper rear stiffener 27 are formed to be shorter than the lower stiffener 28 and are arranged at a distance in the front-rear direction. They are overlapped with the first bulkhead 8 and the second bulkhead 18, respectively. In addition, the upper front stiffener 26 has a tip portion 26a protruding forward of the first bulkhead 8.

The lower stiffener 28 is disposed so as to straddle the first bulkhead 8 and the second bulkhead 18. The lower stiffener 28 has a tip 28a that protrudes forward from the first bulkhead 8. Furthermore, the lower stiffener 28 has a rear end 28b that extends rearward from the second bulkhead 18. The rear end of the front side frame 1 is joined to a rear end member that extends from the inclined surface of the dash lower panel 5 (see FIG. 1) to the underside of the floor of the passenger compartment R. The rear end 28b, which extends along the descending ridge 1d of the rear end of the front side frame 1, is formed so as to descend toward the rear of the vehicle.

In this embodiment 2, the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are configured to have the same plate thickness. The plate thickness of the U-shaped stiffener 16 in embodiment 1 and the plate thickness of the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 may be the same plate thickness. This allows the first bulkhead 8 and the second bulkhead 9 to be constructed from common parts, suppressing an increase in the number of parts. In addition, the plate thickness is the same regardless of which stiffener is used. And by using bulkheads of the same shape, the position of the mounting part can be made the same. Therefore, the mounting part can be standardized between vehicles that require different strengths.

The lower stiffener 28 is extended in the fore-and-aft direction of the vehicle across the first bulkhead 8. The front side frame 1 also has a front weak portion 40 that constitutes the weak portion 20 near the tip 28a that extends forward. The front side frame 1 also has a middle weak portion 42 and a rear weak portion 45 that constitute the weak portion 20 near the first bulkhead 8 or the second bulkhead 18.

As shown in FIG. 5, in the front side frame 1, the tip portion 28a of the lower stiffener 28 on the lower ridge line 1d side extends further forward than the tip portion 26a of the upper front stiffener 26 on the upper ridge line 1c side.
Furthermore, in the front side frame 1, the rear end 28b of the lower stiffener 28 on the lower ridge line 1d side extends rearward beyond the rear end 27b of the upper rear stiffener 27 on the upper ridge line 1c side.

As shown in Fig. 7, the front side frame 1 joins the upper front stiffener 26 and the lower stiffener 28 to the first bulkhead 8 in a manner overlapping in the vehicle width direction and the up-down direction. Note that Fig. 7 does not show the back plate 15 (see Fig. 3). First bolt insertion holes 41 in which fastening nuts are held are formed between the upper front stiffener 26 and the lower stiffener 28 and the first bulkhead 8 (see Fig. 2).
8, a back plate 15 is disposed on the outer side in the vehicle width direction of the front side frame 1. The left and right edges of the back plate 15 in the width direction are joined to folded-back flange portions 1g, 1h of the front side frame 1.
The first bulkhead 8 has a pair of upper and lower tongue pieces 71 , 72 that are sandwiched between the folded flange portions 1 g , 1 h and the back plate 70 .

Furthermore, as shown in FIG. 1, a bumper beam assembly 31 having a bumper beam extension 4 is provided at the front end 1 a of the front side frame 1 via a bumper joining plate 3 .
The bumper beam extension 4 is assembled between the bumper beam and the front end 1a of the front bumper 30 which extends in the vehicle width direction.
As shown in Figure 9, the front end 1a of the front side frame 1 has a hollow structure extending in the fore-and-aft direction, and has an inner wall 12 on the inner side in the vehicle width direction, an outer wall 14 on the outer side in the vehicle width direction that constitutes the outer surface of the front end 2a of the upper member 2, and a reinforcing wall 13 in between that is made of a reinforcing member that serves as a partition within the space inside the front end 1a.
The bumper beam extension 4 is a substantially box-shaped member extending in the front-to-rear direction, and has an extended wall surface 22 on the inside in the vehicle width direction, an extended outer wall 24 on the outside in the vehicle width direction, and an extended wall surface 23 in between.
That is, the bumper beam extension 4 is provided with extended wall surfaces 22, 23, 24 aligned in the front-rear direction with respect to the inner wall 12, reinforcing wall 13, and outer wall 14 constituting the front end 1a. The bumper beam extension 4 is surrounded by upper and lower wall members 4a, 4b provided at the middle position in the vehicle width direction, and left and right extended wall surfaces 22, 24. The internal space of the bumper beam extension 4 is defined by an extended wall surface 23 extending vertically from the opposing portions of the upper and lower wall members 4a, 4b in parallel with the extended wall surfaces 22, 24.
The extension wall surfaces 22 , 23 , 24 are aligned in the front-rear direction with respect to the three inner walls 12 , the reinforcing walls 13 , and the outer walls 14 .

As shown in FIG. 9, the bumper beam extension 4 has extended wall surfaces 22 , 23 , and 24 that are aligned with the inner wall 12 , reinforcing wall 13 , and outer wall 14 that constitute the front end portion 1 a of the front side frame 1 .
As shown by the two-dot chain line in Figure 10, the longitudinal dimension of the extension wall surfaces 22, 23, 24 can be set to be longer than the bumper beam extension 4, which is the reference shown by the solid line. This allows the front bumper 30 to be positioned at a desired distance from the vehicle body, improving compatibility with vehicle types.
The other configurations and effects are the same as or equivalent to those of the vehicle front body structure of the first embodiment, and therefore description thereof will be omitted.

Next, the effects of the vehicle body front structure of this embodiment will be described.
As shown in FIG. 1, the vehicle 10 includes a front side frame 1 extending in the fore-and-aft direction and having at least two ridges 1c, 1d, a stiffener 16 overlapping the two ridges 1c, 1d and extending along the longitudinal direction, and a bulkhead 17 overlapping the stiffener 16.
The stiffener 16 extends in the longitudinal direction of the vehicle across the bulkhead 17 , and the front side frame 1 has a weak portion 20 formed in the vicinity of the bulkhead 17 .

Therefore, deformation occurs reliably at the weak portion 20, and the amount of impact energy absorbed can be increased.
Specifically, the front side frame 1 is reliably bent from the weak portion 20 near the bulkhead 17 where the change in rigidity is large due to the load input from the front. Also, the stiffener 16 breaks together with the two ridges 1c, 1d of the front side frame 1. This makes it possible to increase the amount of impact energy absorption.

As shown in FIG. 3, the stiffener 16 has a substantially U-shaped cross section.
The stiffener 16 having a substantially U-shaped cross section is folded together with the two ridges 1c and 1d of the front side frame 1. This makes it possible to increase the amount of impact energy absorption.

5, the stiffener 16 is formed with a substantially L-shaped cross section with its vertical wall surfaces and horizontal wall surfaces perpendicular to each other. The stiffener 16 has an upper front stiffener 26, an upper rear stiffener 27, and a lower stiffener 28 that extend along the two upper and lower ridgelines 1c, 1d of the front side frame 1, respectively.
The upper front stiffener 26, the upper rear stiffener 27 and the lower stiffener 28, each having a substantially L-shaped cross section, are folded together with the two upper and lower ridgelines 1c, 1d of the front side frame 1. This makes it possible to increase the amount of impact energy absorption.

The stiffener 16 of the first embodiment shown in Fig. 3 and the upper front stiffener 26, upper rear stiffener 27 and lower stiffener 28 of the second embodiment shown in Fig. 6 can be formed with the same plate thickness. In this case, the front side frame 1 having the ridgelines 1c, 1d and the first bulkhead 8 can be configured with common parts.
Also, the shape of the gap 29 is set to a spatial shape that fits each stiffener 16 and stiffeners 26 to 28, etc. In particular, when the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are attached in the second embodiment shown in Fig. 6, a gap 29 is formed that corresponds to the thickness dimension of the U-shaped stiffener 16 of the first embodiment. This makes it possible to change to either the U-shaped stiffener 16 of the first embodiment or the L-shaped stiffener 26 of the second embodiment, etc.

As shown in FIG. 5, the front side frame 1 bends at each of the intermediate weak portions 42 and the rear weak portions 45 when a load is applied from the front.
This increases the amount of deformation over the entire length of the front side frame 1, thereby improving the absorption of the input load. The bulkhead 17 has a first bulkhead 8 provided at least to the engine fastening portion 50 of the front side frame 1, and a second bulkhead 9 provided to a subframe fastening portion 60 disposed rearward of the engine fastening portion 50. The first bulkhead 8 has a first nut 51 facing the first bolt insertion hole 41, and the second bulkhead 9 has a second nut 52 facing the second bolt insertion hole 44.
The front weak portion 40 has an intermediate weak portion 42 having a first bolt insertion hole 41 opening in an upper surface, and a rear weak portion 45 having a second bolt insertion hole 44 opening in a lower surface. By sequentially arranging the intermediate weak portion 42 rearward from the vehicle front of the front side frame 1 at predetermined intervals, a bending point is provided that bends horizontally when a load is input from the front of the vehicle.

That is, the front side frame 1 has, in this order from the front of the vehicle, a first bend point 40a, a second bend point 42a located in the vicinity of the engine fastening portion, and a third bend point 45a located in the vicinity of the sub-frame fastening portion, which are bent alternately in the horizontal direction.
Therefore, the first bending point 40a, the second bending point 42a, and the third bending point 45a are bent in sequence in the vehicle front-rear direction to easily set a desired deformation mode, thereby improving the absorption of the input load.

As shown in FIG. 5, the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are arranged along the two ridges 1c, 1d of the front side frame 1, and the lower stiffener 28 has a tip 28a that extends forward across the first bulkhead 8, and the front side frame 1 has a front weak portion 40 having a first bending point 40a near the tip 28a.

The front side frame 1 is reliably bent from the first bending point 40a of the front weak portion 40 by a load input from the front. In addition, the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28 are bent at the two ridgelines 1c, 1d together with the front side frame 1. That is, by providing the weak portion 20 near the bulkhead, the strength difference is increased, and the structure can be configured so that the weak portion is reliably broken. Therefore, in a bending state over the entire length of the front side frame 1, the generated moment is increased, and the amount of impact energy absorbed can be further increased. As shown in FIG. 5, in the front side frame 1, the tip portion 28a of the lower stiffener 28 on the lower ridgeline 1d side portion extends forward from the tip portion 26a of the upper front stiffener 26 on the upper ridgeline 1c side portion.

In addition, the front side frame 1 is inclined from below the floor along the lower surface of the dash lower, and is bent so as to extend horizontally forward above the floor, so there is a risk that the tip of the front side frame 1 may be deformed and lifted upward by a load input from the front of the vehicle.
However, as shown in Fig. 5, the lower stiffener 28 in this embodiment has a tip 28a extending forward from the tip 26a of the upper front stiffener 26. This improves the rigidity of the front side frame 1 in the direction in which the tip is lifted upward, thereby suppressing deformation. Therefore, deformation in the desired horizontal direction can be promoted.

In addition, in the front side frame 1, the rear end 28b of the lower stiffener 28 on the lower ridge line 1d side extends rearward beyond the rear end 27b of the upper rear stiffener 27 on the upper ridge line 1c side.

The rear end 28b of the lower stiffener 28 extends rearward beyond the rear end 27b of the upper rear stiffener 27 on the upper ridge 1c side. Even when a load is input from the front of the vehicle, the rigidity of the front side frame 1 in the direction in which the tip of the front side frame 1 is lifted upward can be improved to suppress deformation. Therefore, deformation in the desired horizontal direction can be promoted. Furthermore, in the front side frame 1 of embodiment 2, the lower stiffener 28 extends downward to match the shape of the inclined surface of the dash lower panel 5 (see FIG. 1). Therefore, the rigidity of the front side frame 1 in the direction in which the tip of the front side frame 1 is lifted upward can be improved to suppress deformation.

7, the front side frame 1 overlaps and joins the upper front stiffener 26 and the lower stiffener 28 to the first bulkhead 8 in the vehicle width direction. First bolt insertion holes 41 for holding fastening nuts are formed between the upper front stiffener 26 and the lower stiffener 28 and the first bulkhead 8 (see FIG. 2).
A back plate 15 is disposed on the outer side in the vehicle width direction of the front side frame 1. The left and right edges of the back plate 15 in the width direction are joined to folded-back flange portions 1g, 1h of the front side frame 1.
The first bulkhead 8 has a pair of upper and lower tongue pieces 71, 72 that are sandwiched between the folded flange portions 1g, 1h and the back plate 70.

The tongues 71, 72 of the first bulkhead 8 are clamped and joined between the back plate 15 and the front side frame 1 reinforced with the upper front stiffener 26 and the lower stiffener 28. This makes it easy to set the fastening nuts at the desired positions.
Additionally, fastening portions are provided in the portions where the rigidity is improved by the upper front stiffener 26 and the lower stiffener 28 .
Therefore, the fastening parts for the engine mount, transmission mount, subframe, etc. can be provided at any position on the front side frame 1 and fastened with fastening bolts to obtain the desired mounting strength.

As shown in FIG. 1, a bumper beam assembly 31 having a bumper beam extension 4 is provided at a front end 1 a of a front side frame 1 via a bumper joining plate 3 .
Of the bumper beam assembly 31, the left and right bumper beam extensions 4, 4 are assembled between the rear sides of both the left and right ends of the front bumper 30, which extends in the vehicle width direction, and bumper joining plates 3 provided at each front end portion 1a, 1a.
9, the bumper beam extension 4 is provided with extended wall surfaces 22, 23, and 24 that are aligned in the front-rear direction with respect to the inner wall 12, reinforcing wall 13, and outer wall 14 that constitute the front end portion 1a. The bumper beam extension 4 is formed into a substantially box-like shape by covering the periphery of the extended wall surfaces 22, 23, and 24 with upper, lower, left, and right wall members.

The front-rear length of the bumper beam extension 4 can be adjusted by changing the front-rear dimension of the extension wall surfaces 22, 23, and 24, so that the same bumper beam can be fitted to multiple vehicle models. In particular, the extension wall surfaces 22, 23, and 24 of the bumper beam extension 4 are aligned in the front-rear direction with the inner wall 12, reinforcing wall 13, and outer wall 14 that constitute the front end portion 1a of the front side frame 1. Therefore, the desired strength can be easily obtained by calculating and setting the front-rear length of the bumper beam extension 4 that corresponds to the load input from the front.

As described above, the vehicle body front structure of this embodiment can reliably cause the weakened portion 20 to cause deformation of the entire front side frame 1, thereby increasing the amount of impact energy absorption.
Also, each stiffener may have the same plate thickness. In this case, regardless of which stiffener is used, the mount can be configured at the same position using a bulkhead of a common shape. Therefore, by using common parts between vehicle models that require different strengths, such as different vehicle weights, it is possible to suppress an increase in the number of parts, reduce total manufacturing costs, and reduce the number of parts.
For example, the mold for the front side frame 1 is inexpensive because only the horizontal straight portion needs to be made. Furthermore, a stiffener laminated portion of the same plate thickness is formed in a portion of the front side frame 1. This allows the engine fastening portion 50 and the subframe fastening portion 60 to be standardized by aligning the vehicle width direction positions of the first nuts 51 even if the vehicle models are different.

The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are exemplified to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations. Possible modifications of the above-described embodiments are, for example, as follows.

In this embodiment, the stiffener 16 is formed in a different shape but with the same plate thickness as the upper front stiffener 26, the upper rear stiffener 27, and the lower stiffener 28. However, this is not particularly limited, and the stiffeners may be made of, for example, steel plates with different rigidities, fiber materials, or hybrid materials thereof, and may not have to have the same plate thickness. In addition, the plate thickness of the stiffener 16 combined with the first bulkhead 8, etc., at the stiffener stacking portion where the stiffener 16 is stacked on the front side frame 1 may be the same.

In addition, in this embodiment, the first bulkhead 8 and the second bulkhead 9 are used, but this is not particularly limited. For example, a single bulkhead or three or more bulkheads may be used. In other words, the shape, number, and material of the bulkheads are not particularly limited.

1 front side frame 1c, 1d ridge line 10 vehicle 16 stiffener 17 bulkhead 20 weak part

Claims (6)

A front side frame extending in a front-rear direction of the vehicle and having an upper ridgeline and a lower ridgeline ;
An upper stiffener formed with a substantially L-shaped cross section that is overlapped with the upper ridge line and arranged along the longitudinal direction;
A lower stiffener having a substantially L-shaped cross section that has a gap between it and the upper stiffener, is overlapped on the lower ridge line, and is arranged along the longitudinal direction ;
a bulkhead overlapping the upper stiffener and the lower stiffener ;
The upper stiffener has a tip end portion of the upper ridge line side portion extending in the vehicle front-rear direction across the bulkhead,
The lower stiffener has a tip end portion of the lower ridge line side portion extending in the vehicle front-rear direction across the bulkhead,
The tip end of the lower ridge line side portion is extended forward and rearward from the tip end of the upper ridge line side portion of the upper stiffener,
a front side frame having a weak portion formed in the vicinity of the bulkhead, the bulkhead includes a first bulkhead provided at an engine fastening portion of the front side frame, and a second bulkhead provided at a sub-frame fastening portion disposed rearward of the engine fastening portion,
the weak portion includes an intermediate weak portion having a first bolt insertion hole opened on an upper surface thereof and a rear weak portion having a second bolt insertion hole opened on a lower surface thereof, and the weak portions are sequentially arranged rearward from the vehicle front of the front side frame at a predetermined interval, thereby providing a bending point at which the weak portion bends horizontally when a load is input from the front of the vehicle;
2. The vehicle body structure according to claim 1, wherein the first bulkhead has a first nut facing the first bolt insertion hole, and the second bulkhead has a second nut facing the second bolt insertion hole. 3. The vehicle body front structure according to claim 2, wherein the front side frame has, successively in a vehicle fore-and-aft direction, a first bend point, a second bend point located in the vicinity of the engine fastening portion, and a third bend point located in the vicinity of the sub-frame fastening portion, the first bend point being alternately bent in a horizontal direction. 2. The vehicle front body structure according to claim 1, wherein the front side frame is formed with a front weakened portion having a first bending point in the vicinity of the tip end. The front side frame includes a fastening nut that overlaps and joins the upper stiffener and the lower stiffener to the bulkhead in the vehicle width direction and is held between the upper stiffener and the lower stiffener and the bulkhead ;
a back plate disposed on an outer side of the front side frame in a vehicle width direction and joined to a folded flange portion of the front side frame,
2. The vehicle front body structure according to claim 1, wherein the bulkhead has a tongue piece that is sandwiched between the folded flange portion and the back plate. a bumper beam assembly attached to a front end of the front side frame,
The bumper beam assembly includes a bumper beam extending in a vehicle width direction and a bumper beam extension assembled between the front end portions,
2. The vehicle front body structure according to claim 1, wherein the bumper beam extension has an extended wall surface aligned in the front-rear direction with respect to a wall surface constituting the front end portion.

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