JPS6250340B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a front fender for an automobile that is fixed to a vehicle body assembly so as to constitute a part of the vehicle body and covers the upper surface of a front wheel.

Generally, in order to reduce the weight of the entire vehicle body, it is considered to use a front fender made of synthetic resin instead of a steel plate. However, front fenders made of synthetic resin are inferior to those made of steel plate in terms of impact strength, and in particular, the arched part along the top surface of the front wheel and the rear end part on the front pillar side of the vehicle body, except for those two ends. Since there are no attachment points to the assembly, there is a problem in that distortion is likely to occur when an external impact load is applied to them.

In view of the above, an object of the present invention is to provide the above-mentioned front fender, which improves the impact strength of the arched portion and the rear end portion, thereby eliminating the conventional problems.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. A front fender F is fixed to a vehicle body assembly B so as to constitute a part of the vehicle body, and covers the upper surface of a front wheel W.

Front fender F is made of polycarbonate resin,
It is integrally molded using a thermoplastic synthetic resin with relatively excellent impact resistance, such as polycarbonate alloy resin or polycarbonate ABS resin, and it fits along the top surface of the front wheel W.
A thick arched portion 1 forming a band shape in the front and rear, a thick rear end portion 2 located on the front pillar P side of the vehicle body assembly B and forming a vertical band shape, the arched portion 1 and the rear end portion 2. The main body part 3 of the fender is thinner than the main part 3 of the fender. The main part 3 of the fender is gradually made thicker and has an arched part 1.
and connected to the rear end portion 2.

With this configuration, the impact resistance of the arched portion 1 and the rear end portion 2 is increased, and both portions 1,
The impact strength of the front fender F can be improved by preventing stress concentration due to the difference in wall thickness at the connecting portion between the front fender F and the fender main body portion 3.

In addition, a mounting bent portion 4 having a substantially hook-shaped cross section is formed on the inside of the upper edge of the fender main portion 3, and a reinforcing bent portion 5 is formed on the inside of the lower edge of the arched portion 1. The inner corner portions 6 ₁ to 6 ₄ of the bent portions 4 and 5 are formed into circular arc surfaces with a radius of 0.5 mm or more. Thereby, when an impact load is applied to the front fender F, it is possible to prevent the impact load from being concentrated on each of the inner corner portions 6 ₁ to 6 ₄ , thereby avoiding the occurrence of cracks, damage, etc. As a result of experiments, it was found that when the radius of the circular arc surface of each of the inner corners ₆₁ to ₆₄ was set to 0.4 mm or less, stress concentration occurred therein, causing cracking and damage.

The reason why the radius of the circular arc surface of each inner corner portion 6 ₁ to 6 ₄ is set strictly in this way is that the polycarbonate resin and the like have relatively excellent impact resistance.
This is because in order to fully exhibit its characteristics, it is necessary to eliminate stress concentration areas.

Generally, in order to improve the appearance of the outer surface of the front fender F, the cavity surface of the mold is finished with high precision so that the surface roughness is approximately 0.3μ, but the inner surface is visible from the outside. Therefore, the surface roughness of the cavity surface is rough. However, when an impact load is applied to the outer surface of the front fender, a tensile force is applied to the inner surface.
The surface roughness of the inner surface has a large influence on the impact strength of the front fender F. Figure 5 shows the results of a DuPont impact test at -30°C using a flat polycarbonate resin test piece with a thickness of 3 mm and an outer surface roughness of 0.1μ, and varying the inner surface roughness. As is clear from this figure, in order to obtain a Dupont impact value of 270 to 300 Kg·cm, the surface roughness of the inner surface must be 5 μ or less. In the present invention, the cavity surface of the mold is finished with high precision so as to obtain such surface roughness.

The front fender F having the above structure includes a tip a of the arched portion 1, a rear end of the arched portion 1, that is, a lower end b of the rear end portion 2, an upper end c of the rear end portion 2, and a bent portion 4 for mounting. It is attached to the vehicle body assembly B at a total of seven points d to g.

As described above, according to the present invention, there is provided a front fender for an automobile, which is molded from synthetic resin, is fixed to a vehicle body assembly so as to constitute a part of the vehicle body, and covers the upper surface of a front wheel. Excluding the thick arched part that forms a band in the front and back along the top surface, the thick rear end part that forms a band in the top and bottom located on the front pillar side of the vehicle body assembly, the arched part and the rear end part. , the fender main part is thicker than those, and the fender main part is gradually thickened and connected to the arched part and rear end part, so the arched part and rear end part have high impact resistance. Furthermore, it is possible to prevent stress concentration due to the difference in wall thickness at the connecting portion between the two parts and the fender main part, thereby improving the impact strength of the front fender.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a perspective view of an automobile, Fig. 2 is a side view of the front fender, Fig. 3 is a sectional view taken along the line of Fig. Figure 2 is a sectional view taken along the line, and Figure 5 is a graph showing the relationship between surface roughness and DuPont impact value. B...Body assembly, F...Front fender,
W...Front wheel, P...Front pillar, 1...Archied portion, 2...Rear end portion, 3
...Fender main part.

Claims (1)

[Claims] 1. A front fender for an automobile, which is molded from synthetic resin, is fixed to the vehicle body assembly so as to constitute a part of the vehicle body, and covers the upper surface of the front wheel, and has a band shape in the front and rear along the upper surface of the front wheel. a thick arch-shaped portion of the vehicle body assembly; a thick rear end portion that is vertically band-shaped and located on the front pillar side of the vehicle body assembly; and a thinner wall than the arch-shaped portion and the rear end portion; 1. A front fender for an automobile, comprising a fender main portion, the fender main portion having a wall thickness gradually increased and connected to the arch-shaped portion and the rear end portion.