JPH053050U - Bumper mounting structure for automobiles - Google Patents

Abstract

(57) [Summary] [Purpose] Smoothly absorbs shock during a car collision, and
The bumper should be supported sufficiently with respect to the vehicle body with sufficient strength. [Structure] A slit 14 having one end opened in a fastening hole 7 formed in the bumper 2 and the other end extending in a direction away from the vehicle body in the front-rear direction of the vehicle body is formed in the bumper 2 above, and left and right edge portions of the slit 14 are formed. Are thin portions 15 and 15, respectively. The front-rear dimension L of the slit 14 is larger than the front-rear dimension L'of the fastening hole 7.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bumper mounting structure for an automobile, and more particularly, to a structure for absorbing a shock by displacing a position of the bumper with respect to a vehicle body when the automobile collides.

[0002]

[Prior Art]

 A conventional bumper mounting structure is disclosed in, for example, Japanese Utility Model Publication No. 60-137649. This will be described with reference to FIG. The arrow Fr in the figure indicates the front of the vehicle. In the figure, a fastening hole (5) is formed in a resin-made front bumper (1) (symbols in parentheses refer to those in the above publication; the same applies hereinafter), and a fastener (8) inserted through the fastener hole (5) The bumper (1) is screwed to the front part of the vehicle body. Further, the front opening edge of the fastening hole (5) is a thin portion (9). When the bumper (1) is displaced so as to approach the vehicle body while traveling, the trailing edge of the thin portion (9) is pressed against the fastener (8). The pressure contact force starts the fracture of the thin portion (9), and the impact is absorbed as the fracture progresses thereafter.

[0003]

[Problems to be solved by the device]

 By the way, in the above-mentioned conventional structure, since the trailing edge of the thin portion (9) is a continuous arc surface, the trailing edge of the thin portion (9) is pressed against the fastener (8) at the time of the collision. However, internal stress is generated almost uniformly at the trailing edge, and a large pressure contact force is required to initiate fracture. Therefore, the above configuration may not be able to smoothly absorb the shock. It should be noted that if the thickness of the thin portion (9) is made thinner, the initiation of the rupture will be smoother and the above problems will not occur, but in this case, the shock absorption due to the rupture is insufficient. There is an inconvenience.

On the other hand, the resin bumper (1) is usually molded by injection molding. In this case, when the molten resin flows through the cavity of the mold around the fastening hole (5), the two facing, which are clockwise and counterclockwise when viewed from the fastening hole (5), face each other. The tips of the resin streams (X) and (Y) are joined to each other (hereinafter, this joined portion is referred to as a weld portion), whereby the corners of the cavity are filled with resin, and the bumper (1) is molded. Will be done. By the way, in the weld portion (W), due to the joining of the tips of the resin flows (X) and (Y) facing each other, a boundary surface having a weak joining force tends to be formed between them. In the conventional structure, the weld portion (W) is considered to occur at the edge of the fastening hole (5), so that the strength around the fastening hole (5) in the bumper (1) is reduced, and When the fastener (8) is inserted through the fastening hole (5) and the bumper (1) is fastened and supported on the vehicle body side, the support strength of the bumper (1) with respect to the vehicle body may be insufficient. ..

[0005]

[The purpose of the device]

 The present invention has been made in view of the above circumstances, and it is intended to ensure that the shock absorption at the time of a car collision is smoothly and sufficiently performed, and that the bumper is supported to the vehicle body with sufficient strength. The purpose is to be done in.

[0006]

[Means for Solving the Problems]

 A feature of the present invention for achieving the above object is that one end is opened in a fastening hole formed in a bumper, and the other end side is formed with a slit extending in a direction away from the vehicle body in a front-back direction of the vehicle body. The left and right edges of the slit are thin portions, and the front-rear dimension of the slit is larger than the front-rear dimension of the fastening hole.

[0007]

[Work]

 The operation of the above configuration is as follows. A slit 14 is formed in the bumper 2, one end of which is opened in the fastening hole 7 formed in the bumper 2 and the other end of which extends in the front-rear direction of the vehicle body in a direction away from the vehicle body. Are thin portions 15 and 15, respectively. Therefore, when the bumper 2 is displaced so as to approach the vehicle body in the case of a collision of an automobile, the respective end edges 16 of the thin portions 15, 15 on the side of the fastening hole 7 are inserted into the fastening hole 7 as above. The thin-walled portions 15 and 15 are ruptured by the pressure-contacting force applied to the tool 8 at this time, and the progress of the subsequent rupture absorbs the impact and prevents the damage on the vehicle body side.

In the above case, since the slits 14 are present between the left and right thin portions 15, 15, they must reinforce each other when the respective edges 16, 16 receive the pressure contact force. Instead, it transforms individually. Therefore, the breakage of the thin portions 15, 15 can be started smoothly. Further, since the above-described breakage can be started smoothly, it is not necessary to make the thickness of each thin portion 15 very thin.

By the way, in the case where the bumper 2 is injection-molded, when the molten resin flows around the fastening hole 7 and the slit 14 in the cavity of the mold corresponding to the fastening hole 7 and the slit 14, the clockwise direction (see FIG. The tips of the two opposing resin streams flowing in the middle arrow A) and in the counterclockwise direction (arrow B in FIG. 1 above) are joined to each other, whereby the resin fills every corner of the cavity. Then, the bumper 2 is molded.

In the above case, since the front-rear dimension L of the slit 14 is made larger than the front-rear dimension L ′ of the fastening hole 7, the position where the weld portion 17 is formed by joining the tips of the resin flows facing each other is as follows. It tends to occur at the edge of the fastening hole 7 and the slit 14 on the slit 14 side. In this case, since the left-right dimension w of the slit 14 is smaller than the left-right dimension W of the fastening hole 7, the edge portion of the slit 14 has a larger resin capacity than the edge of the fastening hole 7. Conventionally, the bonding force between the resins in the weld portion 17 is higher than in the case where the weld portion is formed at the edge of the fastening hole.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, reference numeral 1 is a sheet metal support piece formed on the rear portion of the vehicle body of the automobile. Reference numeral 2 is a resin-made rear bumper. The bumper 2 includes a bumper body 3 extending in the vehicle width direction along the rear portion of the vehicle body, and a bumper side portion 4 extending forward from each side portion of the bumper body 3. It is configured. The arrow Fr in the figure indicates the front of the vehicle.

In FIGS. 1 to 3, a rectangular support projection 6 is integrally provided on the front end of each bumper side portion 4 so as to inward in the vehicle width direction. The support protrusion 6 extends substantially horizontally and faces the support piece 1, and a circular fastening hole 7 is formed in the front portion of the support protrusion 6.

Reference numeral 8 denotes a fastener, which is composed of a grommet 10 and a screw 11, and the grommet 10 is inserted into the support hole 12 formed in the support piece 1 and the fastening hole 7. On the other hand, the screw 11 is screwed to the grommet 10. As a result, the support projection 6 is screwed to the support piece 1, that is, the bumper 2 is supported by the vehicle body.

Reference numeral 14 denotes a slit. A front end that is one end of the slit 14 opens in the left and right center in the fastening hole 7, and a rear end that is the other end of the slit 14 is separated from the vehicle body in the front-rear direction of the vehicle body. Direction, that is, backward. In this case, the lateral dimension w of the slit 14 is sufficiently smaller than the lateral dimension W (diameter) of the fastening hole 7.

The left and right edges of the slit 14 are thin portions 15 and 15, and the end edges 16 of the thin portions 15 on the fastening hole 7 side form part of the edges of the fastening hole 7. There is. The left and right dimensions of both the thin portions 15, 15 are substantially the same as the left and right dimensions (diameter) of the fastening hole 7. The front-rear dimension L of the slit 14 is larger than the front-rear dimension L '(diameter) of the fastening hole 7.

In the above-mentioned configuration, when the automobile is hit later, the bumper 2 is displaced so as to approach the vehicle body, that is, the bumper 2 tends to be displaced forward. At this time, each edge 16 of the thin portions 15, 15 on the side of the fastening hole 7 is brought into pressure contact with the fastener 8 inserted into the same fastening hole 7, and the thin portion 15 is pressed by the pressure contact force at this time. The breakage of No. 15 starts, and the subsequent breakage absorbs the shock, preventing damage to the vehicle body side.

In the above case, since the slits 14 are present between the left and right thin portions 15, 15, these edges 16 and 16 reinforce each other when they are subjected to the pressure contact force. Instead, it transforms individually. Therefore, the breakage of the thin portions 15, 15 is smoothly started. Further, since the above-described breakage can be started smoothly, it is not necessary to make the thickness of each thin portion 15 very thin, and each thin portion 15 has a certain thickness. Therefore, due to the breakage of these thin portions 15, shock absorption is sufficiently performed.

By the way, in the case where the bumper 2 is injection-molded, when the molten resin flows in the cavity of the mold around the fastening hole 7 and the slit 14, when viewed from these 7, 14 clockwise (see the arrow in FIG. 1). A) and the counter ends of two opposite resin streams flowing counterclockwise (arrow B in FIG. 1 above) are joined together, whereby the resin is filled in every corner of the cavity and the bumper 2 will be molded.

In the above case, since the front-rear dimension L of the slit 14 is larger than the front-rear dimension L ′ of the fastening hole 7, the welded portion 17 is formed by the joining of the tips of the resin flows facing each other. The position of occurrence is to occur at the edge of the fastening hole 7 and the slit 14 on the slit 14 side. In this case, since the left-right dimension w of the slit 14 is smaller than the left-right dimension W of the fastening hole 7, the edge portion of the slit 14 has a larger resin capacity than the hole edge of the fastening hole 7. The bonding force between the resins in the weld portion 17 is higher than that in the case where the weld portion occurs at the edge of the fastening hole. As a result, the strength around the fastening hole 7 is improved, and the bumper 2 is supported to the vehicle body with sufficient strength. Although the above is based on the illustrated example, the mounting structure of the bumper 2 may be applied to a front bumper mounted on the front part of the vehicle body.

[0020]

[Effect of the device]

 According to this invention, one end is opened in the fastening hole formed in the bumper, and the other end side is formed with a slit extending in the direction away from the vehicle body in the front-rear direction of the vehicle body. Therefore, when the bumper is displaced toward the vehicle body in the event of an automobile collision, each edge of the thin-walled part on the side of the fastening hole is pressed against the fastener inserted through the same fastening hole, and the pressure contact force at this time The fracture of the thin portion is started, and the subsequent fracture progresses to absorb the impact and prevent damage to the vehicle body side.

In the above case, since there are slits between the left and right thin portions, when the respective edges receive the pressure contact force, they deform individually without reinforcing each other. Therefore, the breakage of the thin portion can be smoothly started. In other words, shock absorption will be carried out more smoothly than in the conventional case where a large pressure contact force was required to start fracture. Further, since the above-mentioned breakage can be started smoothly, it is not necessary to reduce the thickness of each thin-walled portion so that the shock-absorption can be sufficiently performed by the breakage of these thin-walled portions.

In addition, in the above case, since the front-rear dimension of the slit is larger than the front-rear dimension of the fastening hole, when the bumper is injection-molded, the position where the weld portion occurs is that of the fastening hole and the slit. It tends to occur at the edge on the slit side. Since the lateral dimension of this slit is smaller than the lateral dimension of the fastening hole, the edge of the slit has a larger amount of resin than the edge of the fastening hole. The bonding force between the resins in the weld portion of the present invention is higher than that in the case where it occurs at the hole edge. As a result, the strength around the fastening hole is improved, so that the bumper is supported to the vehicle body with sufficient strength.

[Brief description of drawings]

FIG. 1 is a partial plan view of a bumper.

FIG. 2 is a perspective view.

3 is a sectional view taken along the line 3-3 of FIG.

FIG. 4 is a sectional view taken along the line 4-4 of FIG.

FIG. 5 is a diagram corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

 2 Bumper 6 Supporting protrusion 7 Fastening hole 8 Fastening tool 14 Slit 15 Thin part 16 End edge 17 Weld part

Claims (1)

[Claims for utility model registration] [Claim 1] A bumper mounting structure for an automobile, wherein a fastening hole for inserting a fastener for screwing a resin bumper to a vehicle body is formed in the bumper as above. Is formed in the bumper, and the other end of the slit extends in the front-rear direction of the vehicle body in a direction away from the vehicle body. The left and right edges of the slit are thin portions, and the front-rear dimension of the slit is the same as the fastening hole. Bumper mounting structure for automobiles that is larger than the front and rear dimensions.