JP2991843B2 - Mounting structure of automobile door shock absorbing member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an automobile door impact absorbing member as an aluminum alloy reinforcing member disposed inside an automobile door to protect a human body in the event of a side impact.

[0002]

2. Description of the Related Art As shown in FIG. 9, an aluminum impact bar 1, which is frequently used as a conventional shock absorbing member, is disposed inside a door of an automobile. Functions as a shock absorbing member. The impact bar 1 is fixed to the vehicle body at both ends A and B by bolts and nuts 3 via brackets 2 as shown in FIG. 10 or FIG. FIG.
In FIG. 1, the impact bar 1 is tightened to a bracket 2 welded and fixed to a vehicle body by a bolt nut 3 penetrating in the thickness direction. On the other hand, in FIG. 11, a flange 4 extends from an end of the impact bar 1, and the flange 4 and the bracket 2 are fixed by bolts and nuts 3.

[0003]

When the impact bar 1 described above receives a horizontal impact on the door, the impact bar 1 shown in FIG.
As shown in FIG. 2, it is bent by the impact load P. As a result, the fixed portions of the impact bar 1 at both ends with respect to the bracket 2 tend to be smaller in their mutual capacity. On the other hand, the bracket 2 attempts to maintain its fixed state with respect to the vehicle body. For this reason, the pair of brackets 2 receives a tensile load by the impact bar 1 in a direction approaching each other. Therefore, when an impact load is applied to the door, the conventional mounting structure of the shock absorbing member has a problem that the bracket is easily broken. In order to prevent the bracket 2 to which the impact bar 1 is attached from breaking,
It is necessary not to be broken by a pulling force of 00 kg or more. For this purpose, it is necessary to increase the number of mounting bolts and nuts 3 or to connect the bolt insertion hole of the bracket 2 to the edge of the direction in which the pulling force is applied. It is necessary to take measures such as lengthening the interval. However, when the number of bolts and nuts 3 increases and the size of the bracket 2 increases, the weight of the impact bar including the mounting portion also increases, which is a problem that is contrary to the problem of weight reduction required for automobiles in general. is there.

[0004] The present invention has been made in view of the above problems, and can reliably fix the shock absorbing member to the bracket without substantially increasing the weight.
An object of the present invention is to provide a mounting structure of an automobile door impact absorbing member that can prevent the bracket from breaking even when an impact is applied.

[0005]

A mounting structure for an automobile door impact absorbing member according to the present invention is fixed inside an automobile door.
Bracket aluminum or an aluminum alloy bar that
In a mounting structure for an automobile door shock absorbing member, wherein the end of the shock absorbing member is attached and the shock absorbing member is disposed inside the door, the end of the shock absorbing member and the bracket are fastened with bolts and nuts. The nut or bolt head is fixed to the bracket by welding.

[0006]

In the present invention, a bracket made of iron or the like is fixed to the vehicle body, and both ends of the shock absorbing member are fixed to this bracket by being tightened with bolts and nuts. Further, in the present invention, a head of the nut or the bolt is welded to the bracket. For this reason, when an impact is applied to the shock absorbing member, the shear stress transmitted from the shock absorbing member to the bracket via the bolt and the nut is not a bolt insertion hole provided in the bracket, but a welding portion on the surface of the bracket. Acts on a relatively large area of. This prevents the bracket from breaking due to the shear stress. In this case, when the welding length is W and the maximum thickness of the welding bead is t at the welded portion of the nut,
If W and t are set so as to satisfy × t ≧ 10 (mm ² ), the breakage of the bracket can be reliably prevented.

[0007]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a plan view of a mounting portion showing a mounting structure of a shock absorbing member according to an embodiment of the present invention, FIG. 2 is a side view thereof, and FIG. 3 is an impact bar 11 as a shock absorbing member.
FIG. The impact bar 11 is arranged inside the automobile door similarly to the impact bar 1,
An iron bracket 12 fixed to the vehicle body inside the door,
It is tightened and fixed by bolts 14 and nuts 13. The impact bar 11 has a rectangular cross section,
The bottom surface is overlaid on the bracket 12 and fixed. The bracket 12 and the impact bar 11 are provided with holes for inserting bolts 14 at positions aligned with each other. By inserting the bolts 14 into these holes and screwing the nut 13 into the bolts 14, The impact bar 11 is fastened to the bracket 12.

Then, as described above, the impact bar 11
After being fastened to the bracket 12, the nut 13 is welded to the bracket 12. When the width of the welded portion 15 between the nut 13 and the bracket 12 is W and its maximum thickness is t, the welded portion 15 is set to satisfy W × t ≧ 10 (mm ² ). As shown in FIG. 2, the maximum thickness t of the welded portion 15 is the distance between the position where the side surface of the nut 13 intersects with the surface of the bracket 12 and the surface of the welded portion.

In the mounting structure of the shock absorbing member according to the present embodiment, the nut 13 is connected to the bracket 12 by welding after the nut 13 and the bolt 14 are tightened. The bracket 11 and the bracket 11 are connected by a clamping force tightened by a bolt and a nut, and are also joined by a welded portion 15 between the bracket 13 and the nut 13. For this reason,
Even if an impact force is applied to the impact bar 11 and it is curved, and a tensile force or shear stress is applied to the bracket 12 in a direction in which the connecting portions at both ends of the impact bar 11 approach each other, as in the related art, Unlike the case where the bolt 14 pulls the bracket 12 through the hole of the bracket 12, in the present embodiment, in addition to transmitting the stress through the bolt and the hole, the nut 1 screwed to the bolt 14 is used.
The bracket 12 is pulled via a weld 15 between the bracket 3 and the bracket 12. Therefore, this impact bar 1
The bracket 12 is prevented from being broken by the impact force applied to the bracket 1.

In the above embodiment, the nut 13
Although the bracket 12 and the bracket 12 are welded together, it goes without saying that the head of the bolt 14 and the bracket 12 may be welded. In addition, this welded portion may be formed by welding a part of the nut or bolt head and the bracket, and it is not necessary to form a weld around the entire periphery of the nut or bolt head.

Next, a description will be given of the results of tests on the strength of the connecting portion between the impact bar and the bracket of the present embodiment structure and the connecting portion of the conventional structure until the bracket is broken. FIGS. 4 and 5 are graphs showing the load when the bracket 12 breaks when a tensile force is applied to the bracket 12 in the shear direction by the tensile test method shown in FIG. FIG. 4 shows data in the case where the bracket 12 and the impact bar 11 are fixed by tightening bolts and nuts without welding as in the related art. on the other hand,
FIG. 5 shows the nut 13 and the bracket 1 in this embodiment.
2 are data obtained by welding. As shown in FIG. 6, in this tensile test, the bracket 12 and the impact bar 11 were tightened by bolts 14 and nuts 13. The bracket 12 is made of iron and has a thickness of 1.
2 mm. The height of the impact bar 11 is 6 mm, the diameter of the bolt 14 is 10 mm, and the distance between the center of the connection hole and the edge of the impact bar 11 closest to the center of the hole is 10 mm. The data of FIG. 4 is obtained by variously changing the distance L between the center of the connection hole and the edge of the bracket 12 closest to the hole, and calculating the breaking load of the bracket 12.
The horizontal axis in FIG. 4 is this distance L. On the other hand, in the case of FIG.
The breaking load of the bracket 12 was obtained by keeping the distance L constant at 5 mm and changing t × W variously. This FIG.
As can be seen from a comparison of the data in
At L = 5 mm, there is only a breaking load of 550 kgf, whereas in the case of this embodiment, at L = 5 mm, 800
Has a breaking load of kgf or more. Moreover, the breaking load increases as t × W increases, and particularly, t × W is 1
When it exceeds 0 mm ² , the breaking load becomes 1000 kgf or more, and an extremely high bonding strength is obtained. On the other hand, in the conventional case, in order to obtain the breaking load of 1000 kgf, L must be 16 mm or more, and the length is required to be three times or more that of the present embodiment. Would.

Next, the results of a bending test performed on the impact bar 11 will be described. As shown in FIG.
Bolts 14 are attached to both ends of the impact bar 11 shown in FIG.
The brackets 12 are fastened to each other by the nuts 13 and the brackets 12 are fixed to the pair of support portions 21, and the impact bar 11 is supported between the support portions 21. Then, a bending test was performed by applying a load P to the center of the impact bar 11 using a punch 22 having a circumferential surface with a diameter of 150 mm. Then, the relationship between the load P and the amount of deflection δ was determined.

FIG. 8 shows the result. FIG. 8 is a graph showing the displacement load curve with the deflection (displacement) δ on the horizontal axis and the load P on the vertical axis. The hatched portion surrounded by the load displacement curve is the bracket and impact bar. Corresponds to the amount of energy absorbed until the fixed portion breaks. In the case of the present embodiment (solid line) having a welded portion, the amount of energy absorption is significantly increased, and the amount of deflection (displacement) δ until breakage is larger than that of the conventional example having no welded portion (dashed line). Extremely large.

Table 1 below shows a comparison between the maximum load, the amount of energy absorption and the required weight of the impact bar in the case of the present embodiment and the case of the conventional example until the fracture occurs. In Table 1, each numerical value is an exponential display with respect to the conventional example.

[0016]

[Table 1]

However, the required weight of the impact bar is the total weight of the impact bar for obtaining the same energy absorption. In the case of the conventional example, the distance L (see FIG. 6) from the center of the hole in the bracket of the conventional example is increased, and the number of bolts is further increased so that the bending (displacement) is the same as that of the present example. At this time, the total weight of the aluminum impact bar and the mounting accessories was defined as the total weight of the impact bar. As is clear from Table 1, the maximum load and the energy absorption amount are significantly increased as compared with the conventional case, the required weight of the impact bar is extremely reduced, and the weight can be significantly reduced.

[0018]

According to the present invention, since the bracket and the head of the nut or the bolt are welded together, the breakage of the bracket when the shock absorbing member is subjected to an impact can be suppressed. Can significantly increase the maximum load and energy absorption amount, and can reduce the weight of the shock absorbing member.

[Brief description of the drawings]

FIG. 1 is a plan view showing a mounting structure of a shock absorbing member according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the same.

FIG. 3 is a cross-sectional view of an impact bar.

FIG. 4 is a graph showing the tensile strength when welding is not performed.

FIG. 5 is a graph showing the tensile strength when welding is performed.

FIG. 6 is a schematic diagram illustrating the tensile test method of FIGS.

FIG. 7 is a schematic diagram illustrating a bending test method.

FIG. 8 is a graph showing the impact absorption energy determined by the bending test.

FIG. 9 is a schematic view showing an impact bar arranged in a door of a vehicle.

FIG. 10 is a perspective view showing a conventional impact bar mounting structure.

FIG. 11 is a perspective view showing a conventional impact bar mounting structure.

FIG. 12 is a schematic view showing an impact bar that has been subjected to an impact.

[Explanation of symbols]

 1,11; Impact bar 2,12; Bracket 3,14; Bolt 13; Nut 15;

Continuation of front page (56) References JP-A-4-92718 (JP, A) JP-A-58-87615 (JP, U) JP-A-4-11114 (JP, U) JP-A-59-46749 (JP) , U) Real opening 58-113523 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60J 5/00

Claims (2)

(57) [Claims] 1. A motor vehicle door motor vehicle door made of aluminum or an aluminum alloy bar bracket inside Ru fixed opposition <br/> attach the end of the hammer absorbing member placing the shock absorbing member inside the door In the mounting structure of a shock absorbing member, an end of the shock absorbing member and a bracket are fastened by bolts and nuts, and the nut or bolt head is fixed to the bracket by welding, and the door impact of the automobile is characterized in that Mounting structure for the absorbing member. 2. The welded portion of the nut has a welding length W and a maximum thickness of a welding beat t, W × t ≧ 10 (m
^2. The mounting structure for an automobile door impact absorbing member according to claim 1, wherein W and t are set so as to satisfy m ² ).