JP2013159156A - Vehicle body front structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle body front structure capable of reinforcing a dash panel without reducing space efficiency.SOLUTION: In a vehicle body front structure provided with a dash panel 10, a left reinforcement panel 41 and a right reinforcement panel 42 for enhancing surface rigidity of a dash lower panel 11 are each joined at positions separated to right and left in the dash lower panel 11. An L-shaped reinforcement 50 of an L-shaped cross section in the vehicle vertical direction is joined to the dash lower panel 11 across a corner formed by a general part 11c extending in the vehicle vertical direction and a lower joint flange part 11f. The L-shaped reinforcement 50 is extended in the vehicle width direction and arranged overlapping with the left reinforcement panel 41 and the right reinforcement panel 42 in the vehicle longitudinal direction.

Description

  The present invention relates to a vehicle body front structure that reinforces the rigidity of a dash panel in the vehicle front-rear direction.

  Conventionally, the dash panel provided at the front of the vehicle body is formed by welding the dash upper panel and the dash lower panel up and down by welding, and the dash upper panel is joined to the cowl top panel that supports the windshield. Is common.

In such a vehicle body front structure, a dash panel having a reinforced rigidity in the vehicle front-rear direction is known (see, for example, Patent Document 1).
In Patent Document 1, a dash cross member is formed in the vehicle width direction by forming a closed cross section with the upper rear surface side of the dash lower panel, and further, the dash cross member and the dash upper panel are joined and reinforced. A structure provided with a reinforcing bracket is disclosed.
In this prior art, it is possible to prevent the joint portion between the dash upper panel and the dash lower panel from being swayed in the longitudinal direction of the vehicle body, thereby taking measures against vibration and noise of the vehicle body.

JP 2011-37288 A

  However, in the above-described prior art, the dash cross member forms a closed cross section with the dash lower panel, so that the dash cross member protrudes into the vehicle interior space, which reduces the space efficiency of the vehicle interior space. there were.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle body front structure that can reinforce a dash panel without reducing space efficiency.

  In order to achieve the above object, the vehicle body front structure of the present invention has an L-shaped cross-sectional shape in the vehicle vertical direction across the corner formed by the general portion extending in the vehicle vertical direction and the joint flange portion on the dash lower panel The front part of the vehicle body, characterized in that the L-shaped reinforcement is joined, and the L-shaped reinforcement extends in the vehicle width direction and is overlapped with the left and right reinforcement panels in the vehicle longitudinal direction. The structure.

The vehicle body front part structure of the present invention reinforces the rigidity of the dash panel in the vehicle front-rear direction by an L-shaped reinforcement surface-bonded to the dash lower panel. Space efficiency can be improved.
Moreover, since the L-shaped reinforcement is joined to the corner portion formed by the general portion of the dash lower panel and the joining flange portion, the L-shaped reinforcement is simply a surface joined to the general portion of the dash lower panel. High rigidity can be obtained. In addition, the L-shaped reinforcement is arranged so that both ends in the vehicle width direction overlap the left and right reinforcement panels in the longitudinal direction of the vehicle. High rigidity can be obtained.
As described above, the present invention can reinforce the dash panel without reducing the space efficiency.

FIG. 1 is a front view showing a state in which a portion of a dash panel to which the vehicle body front structure of the embodiment is applied is viewed from the front of the vehicle. FIG. 2 is a longitudinal sectional view showing the vehicle body front structure according to the embodiment, and shows a cross section taken along line S2-S2 in FIG. FIG. 3 is a cross-sectional view showing the vehicle body front structure according to the embodiment, and shows a cross section taken along line S3-S3 in FIG. FIG. 4 is a frequency characteristic diagram showing a simulation result when vibration is generated in the vehicle body front structure according to the embodiment. The solid line shows the result of the present embodiment, and the dotted line shows the result of the comparative example. FIG. 5 is a sound sensitivity characteristic diagram in a predetermined frequency range when vibration is input from the left and right link members of the suspension device. The solid line indicates the characteristics of the present embodiment, and the dotted line indicates the characteristics of the comparative example. . FIG. 6 is a sound sensitivity characteristic diagram of a predetermined frequency range at the time of vibration input from the suspension device, (a) shows the time of input from the compression rod, (b) shows the time of input from the link member, (C) shows the time of input from a strut. As in FIG. 5, the solid line indicates the characteristic of the present embodiment, and the dotted line indicates the characteristic of the comparative example.

The best mode for realizing the vehicle body front structure of the present invention will be described below based on the embodiments shown in the drawings.
(Embodiment 1)
FIG. 1 is a front view showing a state in which a dash panel to which the vehicle body front part structure according to the first embodiment of the present invention is applied is viewed from the front side of the vehicle.
The vehicle body front structure includes a dash panel 10, a cowl top panel 20, a dash lower cross member 30, a left-side reinforcement panel 41, a right-side reinforcement panel 42, and an L-shaped reinforcement 50. 1 and other drawings, the arrow X indicates the vehicle width direction, the arrow Y indicates the vehicle longitudinal direction, and the arrow Z indicates the vehicle vertical direction.

The dash panel 10 is a panel that partitions the engine room ER and the vehicle compartment RM (see FIG. 2), and is formed by joining the upper end portion of the dash lower panel 11 and the lower end portion of the dash upper panel 12.
As shown in FIG. 2, the joining is performed by lower joining flange portion 11f in which the upper end portion of dash lower panel 11 is bent forward of the vehicle and upper joining flange portion 12f in which the lower end portion of dash upper panel 12 is bent forward of the vehicle. Are stacked in the vertical direction of the vehicle and welded together.

  Note that a dash lower cross member 30 having a hat cross-sectional shape welds the upper and lower flanges 31 and 32 to the dash lower panel 11 on the front surface 11a, which is the vehicle front side surface of the lower end portion of the dash lower panel 11, as shown in the figure. Are joined. As shown in FIG. 1, the dash lower cross member 30 is formed by connecting a left dash lower cross member 30a, a central dash lower cross member 30b, and a right dash lower cross member 30c in the vehicle width direction.

  Returning to FIG. 2, the cowl top panel 20 is joined to the upper part of the dash panel 10. The cowl top panel 20 supports a windshield (not shown), and includes a general portion 21 having an inverted L-shaped cross section and a flange portion 22 continuous to the rear upper end of the general portion 21. The flange portion 22 is joined to the upper end portion of the dash upper panel 12, and the general portion 21 is continuous with the upper end of the dash upper panel 12 and extends forward of the vehicle, and forward of the vehicle with respect to the dash upper panel 12. It extends below the vehicle at a position spaced apart from each other. The lower end of the general portion 21 of the cowl top panel 20 is not joined to the dash upper panel 12, and the air box AB formed therebetween has an open cross-sectional structure.

Returning to FIG. 1, left and right reinforcement panels 41 and 42 for increasing the surface rigidity of the dash lower panel 11 are spaced apart from each other in the vehicle width direction. . As shown in FIG. 3 which shows a cross section taken along line S3-S3 in FIG. 1, both of the reinforcements 41 and 42 are joined to a rear surface 11b which is a vehicle rear side surface of the dash lower panel 11. As shown in FIG. 1, it is arranged at a position spaced downward from the dash upper panel 12.
Further, a steering hole cover member 43 for inserting a steering shaft (not shown) is provided at the lower portion of the front surface 11a of the dash lower panel 11.

As shown in FIG. 2, the L-shaped corner portion of the L-shaped corner formed by the lower joint flange portion 11f and the general portion 11c extending downward at the upper end portion of the dash lower panel 11 has an L-shaped reinforcement. 50 is provided.
The L-shaped reinforcement 50 extends in the vehicle front-rear direction and is joined to the lower joint flange portion 11f by welding, and the lower piece extends downward from the upper piece 51 and joined to the general portion 11c of the dash lower panel 11 by welding. 52 and an inverted L-shaped cross section.
Further, as shown in FIG. 1, the L-shaped reinforcement 50 extends in the vehicle width direction, and the both ends in the vehicle width direction are respectively an upper portion of the left-side reinforcement panel 41 and an upper portion of the right-side reinforcement panel 42. Are arranged in the vehicle longitudinal direction.

Next, the operation of the embodiment will be described.
In the description of this operation, problems to be solved by the embodiment will be described.
When a cowl top panel is provided on the upper portion of the dash panel, a structure is known in which a lower end portion of the cowl top panel is joined to the dash upper panel to form a closed cross-section air box therebetween.
However, when the air box is formed in this way, the rigidity of this portion becomes higher than necessary, and the desired rigidity may not be obtained.
On the other hand, when the air box has an open cross-sectional shape, the rigidity of the air box portion can be reduced to a desired rigidity, but the dash panel has insufficient rigidity in the front-rear direction, which may cause vehicle body vibration or vehicle body noise. .

  With the technique described in Patent Document 1, it is possible to increase the rigidity of the dash panel in the vehicle front-rear direction, but the space efficiency decreases as described above. As a result, when a dash insulator for improving sound vibration performance is provided on the rear surface of the dash panel, the dash cross member may interfere with the installation, and the dash insulator installation amount and installation area may be insufficient. As a result, sound vibration performance may be insufficient from the middle frequency to the high frequency.

On the other hand, the vehicle body front part structure of the present embodiment has the following effects.
a) In the front body structure of the first embodiment,
A vehicle body front portion having a dash panel 10 formed by joining the upper portion of the dash lower panel 11 and the lower portion of the dash upper panel 12 to each other between the joint flange portions 11f and 12f extending in the vehicle front-rear direction from the respective panels 11 and 12. Structure,
In the dash lower panel 11, a left-side reinforcement panel 41 and a right-side reinforcement panel 42 for increasing the surface rigidity of the dash-lower panel 11 are joined to the left and right positions, respectively.
An L-shaped reinforcement 50 having an L-shaped cross section in the vehicle vertical direction is joined to the dash lower panel 11 across the corner formed by the general portion 11c extending in the vehicle vertical direction and the lower joint flange portion 11f.
The L-shaped reinforcement 50 extends in the vehicle width direction and is arranged so as to overlap the left-side reinforcement panel 41 and the right-side reinforcement panel 42 in the vehicle front-rear direction.
As described above, the L-shaped reinforcement 50 is joined to the lower joint flange portion 11 f and the general portion 11 c of the dash lower panel 11, and a closed cross section is formed between the L-shaped reinforcement 50 and the dash lower panel 11. Because there is no space efficiency.
Moreover, the L-shaped reinforcement 50 is joined at both ends in the vehicle width direction to the dash lower panel 11 at positions overlapping with both the reinforcement panels 41 and 42 for improving the surface rigidity of the dash lower panel 11 in the vehicle front-rear direction. For this reason, the rigidity of the dash panel 10 can be improved as compared with a structure in which the L-shaped reinforcement 50 is simply joined to the dash lower panel 11. In addition, since the reinforcement effect of the L-shaped reinforcement 50 is further enhanced by using both the reinforcement panels 41 and 42 installed to increase the surface rigidity of the dash lower panel 11, a dedicated reinforcement panel is provided. Compared with the economics.
Thus, the present embodiment can reinforce the dash panel without reducing the space efficiency.

b) The front body structure of the first embodiment is
Lower joint flange 11f extends forward of the vehicle,
The L-shaped reinforcement 50 was joined to the front surface of the dash lower panel 11 and the lower surface of the lower joint flange portion 11f.
For this reason, the rear surface of the dash lower panel 11 on the vehicle compartment RM side is not formed with a convex portion on the vehicle compartment side due to the installation of the L-shaped reinforcement 50, and the space efficiency on the vehicle compartment RM side is improved. Can do. And the L-shaped reinforcement 50 does not become a hindrance when providing the dash insulator for sound vibration performance improvement in the compartment side of the dash panel 10, and can improve sound vibration performance.

c) The front body structure of the first embodiment is
A cowl top panel 20 extends from the top of the dash upper panel 12 to the front of the vehicle,
The lower end portion of the cowl top panel 20 and the dash upper panel 12 are separated from each other, and the air box AB formed therebetween is formed in an open cross-sectional shape.
Therefore, the dash panel can be reinforced without lowering the space efficiency as in the case a) while the rigidity of the front upper part of the vehicle can be prevented from becoming higher than necessary.

Next, the sound vibration effect described in the above a) will be described.
FIG. 4 is a frequency characteristic diagram showing a simulation result when vibration is generated in the vehicle body front structure according to the embodiment. The solid line shows the result of the present embodiment, and the dotted line shows the result of the comparative example. In the comparative example, the L-shaped reinforcement 50 is not installed.
As shown in this figure, it can be seen that the sound pressure level is lowered in a wide frequency range between n2 and n4, and that there is a reduction effect of about 1 dB at the maximum.

FIG. 5 is a diagram showing sound sensitivity characteristics in a predetermined frequency range when vibration is input from the left and right link members of the suspension device (not shown), which is a portion that contributes particularly greatly to the above-described vibration suppression effect.
In FIG. 5, as in FIG. 4, the solid line indicates the result of the present embodiment, and the dotted line indicates the result of the comparative example. As shown in FIG. 5, in this embodiment, the sound pressure level is lower than the target level in the region R where the comparative example is higher than the target level ML in the frequency region where the frequency exceeds n2. I understand.

  FIG. 6 is a characteristic diagram of sound sensitivity in a predetermined frequency range when vibration is input from the suspension device (not shown). (A) shows the time of input from a compression rod (not shown). ) Shows the time of input from a link member (not shown), and (c) shows the time of input from a strut (not shown).

  As shown in these figures, a sound vibration input suppression effect is obtained in a predetermined frequency range Ra, Rb, Rc where the frequency exceeds n2, and in particular, the sound vibration input suppression effect with respect to the input from the link member as described above. I understand that it is expensive.

  As described above, the vehicle body front structure of the present invention has been described based on the embodiment. However, the specific configuration is not limited to this embodiment, and the invention according to each claim of the claims is not limited thereto. Design changes and additions are allowed without departing from the gist.

For example, in the embodiment, the L-shaped reinforcement, the left-side reinforcement panel, and the right-side Leon force are set on different front and rear surfaces of the dash lower panel, but both may be set on the same front and rear surfaces. May be set upside down.
In the embodiment, the lower end of the cowl top panel is not joined to the dash lower panel so that the air box has an open cross-sectional structure. However, the air box may be closed to have a closed cross-sectional structure. In this case, it is preferable to set a weak portion for setting the rigidity of the air box to a desired rigidity on the cowl top panel or the like.

DESCRIPTION OF SYMBOLS 10 Dash panel 11 Dash lower panel 11c General part 11f Lower joint flange part 12 Dash upper panel 20 Cowl top panel 41 Left side reinforcement panel 42 Right side reinforcement panel 50 L-shaped reinforcement AB Air box RM Car compartment

Claims (3)

A vehicle body front structure including a dash panel formed by joining an upper portion of a dash lower panel and a lower portion of a dash upper panel with joining flange portions extending in the vehicle front-rear direction from each panel,
In the dash lower panel, left and right reinforcement panels for increasing the surface rigidity of the dash lower panel are joined to positions separated from each other on the left and right,
An L-shaped cross section of L-shaped cross section in the vertical direction of the vehicle is joined to the dash lower panel across the corner formed by the general portion extending in the vertical direction of the vehicle and the connecting flange portion,
A vehicle body front structure characterized in that the L-shaped reinforcement extends in the vehicle width direction and is arranged so as to overlap the left-side reinforcement panel and the right-side reinforcement panel in the vehicle front-rear direction. In the vehicle body front part structure according to claim 1,
The joining flange portion extends forward of the vehicle,
The vehicle body front part structure, wherein the L-shaped reinforcement is joined to a vehicle front surface of the dash lower panel and a lower surface of the joining flange portion. In the vehicle body front part structure according to claim 1 or claim 2,
From the upper part of the dash upper panel, a cowl top panel extends forward of the vehicle,
A vehicle body front structure characterized in that a lower end portion of the cowl top panel and the dash upper panel are separated from each other, and an air box formed therebetween is formed in an open cross-sectional shape.