JPH05254344A - Fitting structure of shock absorbing member for door of automobile - Google Patents

Abstract

PURPOSE:To restrict the breakage of a bracket in the case where a shock absorbing member receives the shock, and increase the maximum load to the breakage and the energy absorption quantity remarkably, and lighten a shock absorbing member by welding to join a bracket to a nut or the head of a bolt. CONSTITUTION:An end of a shock absorbing member 11 and a bracket 12 fixed to the inside of a door of an automobile are fastened by a bolt 14 and a nut 13, and the nut 13 or the head of the bolt 14 is fixed to a bracket 12 by welding 15. In the case where the shock is applied to the shock absorbing member 11, the shearing stress to be transmitted from the shock absorbing member 11 to the bracket 12 through the bolt 14 and the nut 13 works not in a bolt insertion hole provided in the bracket 12 but in a relatively wide range of the welding part 15 of the surface of the bracket 12. Breakage of the bracket 12 by the shearing stress is thereby prevented.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art An impact bar 1 made of aluminum, which is widely used as a conventional shock absorbing member, is arranged inside an automobile door as shown in FIG. 9, and when the door is reinforced to receive an impact. It 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. Figure 10
In the above, the impact bar 1 is tightened to the bracket 2 welded and fixed to the vehicle body by the bolt nut 3 penetrating in the thickness direction. On the other hand, in FIG. 11, a flange 4 extends from the end of the impact bar 1, and the flange 4 and the bracket 2 are fixed by a bolt nut 3.

[0003]

The above-mentioned impact bar 1 will not move when a horizontal impact is applied to the door.
As shown in FIG. 2, the impact load P bends. As a result, the fixed portions of both ends of the impact bar 1 with respect to the bracket 2 tend to have a small mutual gap. On the other hand, the bracket 2 tries to maintain the fixed state with respect to the vehicle body. Therefore, the pair of brackets 2 receives a tensile load in the direction in which they approach each other by the impact bar 1. Therefore, when a shock load is applied to the door, the conventional mounting structure of the shock absorbing member has a drawback that the bracket is easily broken. In order to prevent breakage of the bracket 2 to which the impact bar 1 is attached,
It is necessary not to break against a tensile force of 00 kg or more. For this purpose, the number of mounting bolt nuts 3 should be increased or the bolt insertion hole of bracket 2 and the edge in the direction in which the tensile force is applied. It is necessary to take measures such as lengthening the interval. However, when the number of the bolts and nuts 3 increases or the bracket 2 increases in size in this way, the weight of the impact bar including the mounting portion increases, which is contrary to the problem of weight reduction required for automobiles in general. is there.

The present invention has been made in view of the above problems, and the shock absorbing member can be securely fixed to the bracket without causing a substantial increase in weight.
An object of the present invention is to provide a mounting structure for an automobile door impact absorbing member, which can prevent the bracket from breaking even when an impact is applied.

[0005]

According to the present invention, there is provided a mounting structure for an automobile door impact absorbing member, wherein an end portion of the impact absorbing member is attached to a bracket fixed to the inside of the automobile door so that the impact absorbing member is installed inside the door. In the mounting structure of the automobile door impact absorbing member arranged in, the end portion of the impact absorbing member and the bracket are fastened by bolts and nuts, and the nut or bolt head is fixed to the bracket by welding. And

[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 the bracket by tightening bolts and nuts. Further, in the present invention, the head portion of the nut or the bolt is welded to the bracket. Therefore, when a shock is applied to the shock absorbing member, the shear stress transmitted from the shock absorbing member to the bracket through the bolt and nut is not the bolt insertion hole provided in the bracket but the welded portion on the surface of the bracket. Acts on a relatively large area of. This prevents the bracket from breaking due to this shear stress. In this case, when the welding length is W and the maximum thickness of the welding bead is t in the welded portion of the nut, W is W.
If W and t are set so as to satisfy xt ≧ 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 which is a shock absorbing member.
FIG. The impact bar 11 is arranged inside the automobile door like the impact bar 1,
On the iron bracket 12 fixed to the car body inside the door,
The bolt 14 and the nut 13 are tightened and fixed. The impact bar 11 has a rectangular cross section,
The bottom surface of the bracket 12 is overlapped and fixed on the bracket 12. The bracket 12 and the impact bar 11 are provided with holes for inserting the bolts 14 at positions matching 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. The welded portion 15 between the nut 13 and the bracket 12 is set to satisfy W × t ≧ 10 (mm ² ), where W is the width and t is the maximum thickness. As shown in FIG. 2, the maximum thickness t of the weld 15 is the distance between the position where the side surface of the nut 13 and the surface of the bracket 12 intersect and the surface of the weld.

In the mounting structure of the shock absorbing member of the present embodiment thus constructed, since the nut 13 is joined to the bracket 12 by welding after the nut 13 and the bolt 14 are tightened, the impact bar. 11 and the bracket 12 are connected by a pinching force tightened by a bolt and nut, and are also joined by a welded portion 15 between the nut 13 and the bracket 12. For this reason,
Even if an impact force is applied to the impact bar 11 to bend it and a tensile force or a 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 conventional case, Unlike the case where the bolt 14 pulls the bracket 12 through the hole of the bracket 12, in the case of the present embodiment, in addition to transmitting the stress through the bolt and the hole, the nut 1 that is screwed into the bolt 14 is used.
The bracket 12 is pulled through the weld 15 between the bracket 3 and the bracket 12. Therefore, this impact bar 1
The bracket 12 is prevented from breaking due to the impact force applied to the bracket 1.

In the above embodiment, the nut 13
The bracket 12 and the bracket 12 are welded to each other, but the head of the bolt 14 and the bracket 12 may be welded. Further, the welded portion may be formed by welding a part of the head portion of the nut or bolt and the bracket, and it is not necessary to form the welded portion on the entire circumference of the head portion of the nut or bolt.

Next, the results of testing the strength until the bracket breaks at the connecting portion between the impact bar and the bracket of the structure of this embodiment and the connecting portion of the conventional structure will be described. 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 shearing 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 bolt nuts without welding as in the conventional case. on the other hand,
FIG. 5 shows the nut 13 and the bracket 1 in this embodiment.
It is data when 2 and 2 are welded and joined. As shown in FIG. 6, in this tensile test, the bracket 12 and the impact bar 11 were tightened with bolts 14 and nuts 13. The bracket 12 is made of iron and has a thickness of 1.
It is 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 connecting hole and the edge of the impact bar 11 closest to the center of the hole is 10 mm. Further, the data in FIG. 4 is obtained by varying the distance L between the center of the connecting hole and the edge of the bracket 12 closest to this hole, and determining the breaking load of the bracket 12.
The horizontal axis of 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. These Figures 4 and 5
As is clear from the 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
It has a breaking load of kgf or more. Moreover, this breaking load increases as t × W increases, and in particular, t × W is 1
When it exceeds 0 mm ² , the breaking load is 1000 kgf or more, and extremely high bond strength is obtained. On the other hand, in the conventional case, in order to obtain the breaking load of 1000 kgf, L needs to be 16 mm or more, which is three times or more as long as in the case of the present embodiment, and this joint portion becomes large. Will end up.

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

The results are shown in FIG. This FIG. 8 is a graph showing the displacement load curve by taking the deflection (displacement) δ on the horizontal axis and the load P on the vertical axis. The shaded area surrounded by this load displacement curve is the bracket and the impact bar. This corresponds to the amount of energy absorbed until the fixed parts of and are broken. 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 flexure (displacement) δ until breakage is significantly increased compared to the case of the conventional example (broken line) having no welded portion. Extremely large.

Table 1 below shows a comparison between the maximum load until the breakage, the energy absorption amount and the required weight of the impact bar in the case of this embodiment and the case of the conventional example. In addition, in Table 1, each numerical value is an index display with respect to the case of 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 amount. In the case of the conventional example, the distance L (see FIG. 6) from the hole center in the bracket of the conventional example is lengthened so that the flexure (displacement) is the same as that of this example, and the number of bolts is further increased. The total weight of the aluminum impact bar and the attached accessories at this time was taken as the total weight of the impact bar. As is clear from Table 1, the maximum load and the energy absorption amount are remarkably increased as compared with the conventional case, the required weight of the impact bar is remarkably reduced, and the weight can be remarkably reduced.

[0018]

According to the present invention, since the bracket and the head of the nut or bolt are welded to each other, it is possible to suppress the breakage of the bracket when the shock absorbing member receives a shock, and the breakage occurs. It is possible to remarkably increase the maximum load and the amount of energy absorption and reduce the weight of the shock absorbing member.

[Brief description of 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 vertical sectional view of the same.

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

FIG. 4 is a graph showing tensile strength without welding.

FIG. 5 is a graph showing tensile strength in the case of welding and joining.

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 obtained by this bending test.

FIG. 9 is a schematic view showing an impact bar arranged inside a door of an automobile.

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

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

FIG. 12 is a schematic diagram showing an impact bar that has received an impact.

[Explanation of symbols]

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

Claims (2)

[Claims] 1. A mounting structure for an automobile door impact absorbing member, wherein an end portion of the impact absorbing member is attached to a bracket fixed inside an automobile door, and the impact absorbing member is arranged inside the door. An automobile door impact absorbing member mounting structure, wherein an end portion and a bracket are fastened with a bolt and a nut, and the nut or the bolt head portion is fixed to the bracket by welding. 2. The weld portion of the nut has a length W × t ≧ 10 (m) where W is a weld length and t is a maximum thickness of the weld bead.
The mounting structure for an automobile door shock absorbing member according to claim 1, wherein W and t are set so as to satisfy m ² ).