JPS625403Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a soft bumper in which a bumper face containing an energy absorbing plastic foam (foamed resin material) is attached to a back-up beam of a vehicle body, and particularly relates to its deformation prevention structure.

Generally, in this type of soft bumper, a material with a relatively large linear expansion coefficient and low rigidity, such as modified polypropylene, is used as the material of the bumper face containing the energy-absorbing plastic foam, and a material with a relatively low rigidity, such as modified polypropylene, is used as the material of the back-up beam. Since a material having a relatively small linear expansion coefficient and high rigidity is used, when the temperature rises, the bumper face deforms due to the difference between the two expansion coefficients, resulting in a so-called waving phenomenon.

The present invention is intended to solve these problems, and aims to provide a deformation prevention structure for a soft bumper that prevents the bumper face from waving even at high temperatures.

For this reason, the deformation prevention structure of the soft bumper of the present invention is such that a soft bumper consisting of a bumper ace containing a built-in plastic foam for energy absorption is attached to a backup beam having a smaller coefficient of thermal expansion than the bumper ace. In order to prevent deformation of the bumper ace due to the difference in thermal expansion coefficient with the beam, cutouts for absorbing thermal expansion were formed on the inside of the corner parts of the left and right sides of the bumper ace that wrap around the sides of the vehicle body. It is a feature.

Hereinafter, the deformation prevention structure of a soft bumper as an embodiment of the present invention will be explained with reference to the drawings.
FIG. 1 is a plan view of the bumper face, and FIG. 2 is a sectional view thereof. The bumper face 1 has a built-in plastic foam 2 for energy absorption.

The bumper face 1 is made of a material such as modified polypropylene which has a relatively large coefficient of linear expansion and low rigidity, and the energy absorbing plastic form 2 is made of a material such as urethane.

Further, the bumper face 1 is fixed with clips 4 or bolts to a backup beam 3 made of a material such as iron which has a smaller coefficient of linear expansion and greater rigidity than the bumper face 1, thereby forming a soft bumper S. .

In FIG. 1, reference numeral 1a indicates a bolt insertion hole formed in the bumper face 1, and reference numeral 1b indicates a clip insertion hole also formed in the bumper face 1.

By the way, as shown in FIG. 1, there are notches 5, 1c on the inner sides 1c, 1c of the corner portions of the left and right sides of the bumper ace 1 that wrap around the side surfaces of the vehicle body, respectively.
Therefore, even if the bumper face 1 is relatively extended due to the difference in linear expansion coefficient between the bumper face 1 and the back-up beam 3, the amount of elongation, that is, the amount of thermal expansion is absorbed by both the notches 5, 5, and thereby the so-called waving phenomenon of the bumper ace 1 can be reliably prevented.

That is, these notches 5, 5 act as notches for absorbing the amount of thermal expansion.

Note that the width of the notch 5 is set to be larger than the set amount of thermal expansion, and preferably set to about twice the set amount of thermal expansion.

Further, in addition to forming the cutout portions 5 on the inner sides 1c, 1c of both corner portions of the bumper face 1, they can also be formed at appropriate positions on the inner intermediate portion 1d.

Furthermore, instead of forming the notch 5 as a U-shaped notch, it is also possible to form it as a punch in an appropriate shape (circle, oval, etc.).

In the above-mentioned embodiment, the plurality of clip insertion holes 1 formed in the inner middle part of the bumper face 1 are
B, the bumper face 1 is fixed to the back up beam 3 by inserting the clips 4 through each of the clips, but all or part of the plurality of clip insertion holes are inserted along the length direction of the bumper. By forming an elongated hole and inserting a clip into the elongated hole, the bumper face 1 may be attached to the back-up beam 3 without shaking. In this case, there is an advantage that the amount of thermal expansion between the clip attachment parts can also be absorbed.

As described in detail above, according to the deformation prevention structure of the soft bumper of the present invention, the notches 5 for absorbing thermal expansion are provided on the inner sides 1c and 1c of the corner portions that go around the vehicle body side surfaces on both left and right sides of the bumper face 1, respectively.
is formed, the deformation of the bumper face 1 due to the difference in thermal expansion coefficient between the bumper face 1 and the back-up beam 3 can be sufficiently absorbed by the notch 5, and as a result, even at high temperatures, the soft bumper S has the advantage of not causing deformation.

[Brief explanation of the drawing]

The figures show a structure for preventing deformation of a soft bumper as an embodiment of the present invention, and FIG. 1 is a plan view of the bumper face, and FIG. 2 is a sectional view thereof. 1... Bumper ace, 1a... Bolt insertion hole, 1b... Clip insertion hole, 1c... Inside corner of bumper ace 1, 1d... Inner middle part of bumper ace 1, 2... Plastic foam for energy absorption, 3... …backup beam,
4... Clip, 5... Notch for absorbing thermal expansion,
S...Soft bumper.

Claims (1)

[Scope of utility model registration request] In a soft bumper in which a bumper ace with a built-in plastic foam for energy absorption is attached to a backup beam whose thermal expansion coefficient is smaller than that of the bumper ace, deformation of the bumper ace due to the difference in thermal expansion coefficient between the bumper ace and the backup beam is considered. In order to prevent deformation, a structure for preventing deformation of a soft bumper, characterized in that cutouts for absorbing thermal expansion are formed inside the corner portions of the left and right sides of the bumper face that wrap around the side surfaces of the vehicle body.