Resin outer panel member

Abstract

To provide a resin outer panel member capable of preventing the occurrence of a poor appearance caused by thermal strain irrespective of its shape or a fixing form with an inner panel member.SOLUTION: A resin outer panel member 10 comprises: a regulation region 13 regulated in elongation in a direction along a surface in a state where a part of a peripheral edge 10a is fixed to an inner panel member; and a folding part 16 provided at a position sandwiching a part 14 of the peripheral edge of the regulation region 13 fixed to the inner panel member and the center 13a of the regulation region 13 and formed into a shape folded toward the center 13a of the regulation region 13. The thickness ts2 of the folding part 16 on both sides in a width direction is smaller than the thickness tc2 of the folding member 16 on the center side in the width direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a resin outer panel member, and more particularly to a technique for suppressing deformation of a resin outer panel member due to thermal stress. [Background technology]

[0002] In recent years, as part of efforts to reduce environmental impact by improving fuel efficiency in vehicle tailgates such as automobiles, at least one of the tailgate outer and tailgate inner components that make up the tailgate has been formed from resin, which is lighter than metal (see, for example, Patent Document 1).

[0003] In this case, the back door outer is adhesively fixed to the peripheral edge of the back door inner in order to simultaneously provide a sealing structure and a fixing structure (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-124346 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-167697 Summary of the Invention [Problem to be solved by the invention]

[0005] Since the tailgate outer is located on the outer surface of the vehicle, it is more likely to become hot than the tailgate inner. For example, if a vehicle is left in the scorching sun for a long period of time in midsummer, the temperature of the tailgate outer (particularly the top surface of the tailgate outer upper) can reach 80 to 100°C. In such a high temperature, the tailgate outer attempts to thermally expand. However, if the tailgate outer is adhesively fixed to the peripheral edge of the tailgate inner as described above, the adhesive fixation restricts deformation along its plane, resulting in thermal stress. In particular, if the tailgate outer is made of resin, the amount of thermal expansion increases compared to a metal tailgate. Furthermore, if a rear spoiler is integrally formed with the tailgate outer, the rear end of the top surface of the tailgate outer upper that constitutes the rear spoiler will be folded forward. This portion has high geometric rigidity (resistance to deformation due to its shape) and is likely to become a starting point for stress concentration. Therefore, if the thermal stress (thermal strain) generated in the back door outer increases beyond a predetermined level, it may cause deformation (poor appearance) such that the top surface of the back door outer upper becomes wavy and concave along its width direction.

[0006] In view of the above circumstances, the technical problem to be solved in this specification is to provide a resin outer panel member that can prevent poor appearance due to thermal distortion regardless of its shape or the manner in which it is fixed to the inner panel member. [Means for solving the problem]

[0007] The above-mentioned problems are solved by a resin outer panel member according to the present invention. Specifically, the outer panel member is a resin outer panel member that, together with an inner panel member, constitutes an exterior part of a vehicle, and is characterized by having a restriction region in which stretching along the surface is restricted when a portion of a peripheral edge is fixed to the inner panel member, and a folded portion that is provided between the portion of the peripheral edge of the restriction region that is fixed to the inner panel member and the center of the restriction region and is folded back toward the center of the restriction region, and the thickness dimensions on both sides of the folded portion in the width direction are set smaller than the thickness dimension at the center of the width direction of the folded portion. Note that the width direction of the folded portion here refers to the direction perpendicular to the folding direction of the folded portion.

[0008] The inventors conducted thermal stress analysis of a resin outer panel under specified constraint conditions to examine its deformation. The results showed that, within the peripheral edge of the region where elongation along the surface is restricted when the outer panel is fixed to the inner panel by adhesive or other means, stress concentration is particularly pronounced at or near the portion fixed to the inner panel and the folded portion located between the fixed portion and the center of the restricted region. Furthermore, the stress concentration region expands (stretches) across the center of the restricted region, resulting in a displacement in the thickness direction (concave deformation). Based on these findings, the present invention sets the thickness dimensions of both sides of the folded portion in the width direction smaller than the thickness dimension at the center of the folded portion, which is the origin of stress concentration. This configuration distributes stress from the relatively thick region of the folded portion to the relatively thin region. This minimizes stress concentration at the center of the folded portion, thereby suppressing the expansion of the stress concentration region and, ultimately, thermal distortion in the restricted region. Therefore, according to the present invention, it is possible to prevent, as much as possible, the occurrence of defects in appearance such as concave deformation in the resin outer panel member.

[0009] Furthermore, in the resin outer panel member of the present invention, the folded portion is composed of a first plate-shaped portion connected to the restriction area, a bending portion connected to the first plate-shaped portion, and a second plate-shaped portion connected to the bending portion and extending in a direction different from the first plate-shaped portion, and the thickness dimension of the folded portion on both sides of the bending portion in the width direction may be set smaller than the thickness dimension at least at the center of the bending portion in the width direction.

[0010] As described above, by setting the thickness dimension of the bent portion on both sides of the folded portion in the width direction to be smaller than the thickness dimension of the bent portion on the center side in the width direction, it is possible to effectively alleviate stress concentration that occurs in the folded portion while maintaining the rigidity of the portion connected to the restriction area as high as possible.

[0011] Furthermore, since the resin outer panel member described above can prevent poor appearance due to thermal distortion regardless of its shape, it can be suitably provided, for example, as a resin tailgate outer upper in which a restriction area is provided on the top surface of the tailgate outer upper and the rear end of a rear spoiler is provided as a folded portion on the rear end side of the top surface.

[0012] In this case, it is preferable that the ratio of the area of ​​the folded portion that is relatively thick in the width direction to the entire area in the width direction is set to 10% or more and 25% or less.

[0013] The inventors further verified the optimum ratio of thick and thin regions in the folded portion through a thermal stress analysis of a plastic rear door outer upper, and found that the stress dispersion effect of the folded portion described above can be achieved if the ratio of the thick regions to the entire width direction is approximately 10% or more and 25% or less. Therefore, by setting the ratio of the thick regions to the entire width direction to be 10% or more and 25% or less, it is possible to distribute thermal stress to both sides in the width direction while ensuring the necessary rigidity, and to prevent as much as possible not only the occurrence of thermal distortion due to stress concentration but also the occurrence of thermal distortion due to insufficient rigidity. [Effects of the Invention]

[0014] As described above, the resin outer panel member according to the present invention can prevent appearance defects due to thermal distortion, regardless of its shape or the manner in which it is fixed to the inner panel member. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a resin back door outer upper according to one embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a plan view of the back door outer upper shown in FIG. [Figure 3] 3A is a cross-sectional view taken along line AA on the center side in the width direction of the back door outer upper shown in FIG. 2, and FIG. 3B is a cross-sectional view taken along line BB on one side in the width direction. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a resin outer panel member according to one embodiment of the present invention will be described with reference to the drawings. In this embodiment, the resin outer panel member will be described using an automobile back door outer upper as an example.

[0017] 1 shows a perspective view of a tailgate outer upper 10 according to one embodiment of the present invention. The tailgate outer upper 10 is made of resin and constitutes a tailgate for an automobile together with a tailgate inner (not shown) as an inner panel member, and has a rear spoiler 11 integrally formed therewith.

[0018] In this embodiment, the back door outer upper 10 is fixed to the peripheral edge of the back door inner panel by adhesive or the like. Therefore, almost the entire peripheral edge 10a of the back door outer upper 10 is adhesively fixed to the peripheral edge of the back door inner panel. In this case, the entire top surface 12 of the back door outer upper 10 constitutes the restriction area 13 according to the present invention. An adhesive fixing portion 14 is provided on the peripheral edge of the top surface 12 at or near an open side edge 12a extending in the width direction, and downward bent portions 15 are provided on both sides of the peripheral edge in the width direction. In addition, a folded portion 16 is provided on the peripheral edge of the top surface 12 between the open side edge 12a (adhesive fixing portion 14) and the central portion 13a of the restriction area 13, and is folded back toward the central portion 13a of the restriction area 13 (see FIG. 3 described later). This folded portion 16 constitutes the rear end of the rear spoiler 11.

[0019] Next, the thickness distribution in the folded portion 16 will be described mainly with reference to FIG.

[0020] FIG. 3(a) shows a cross-sectional view of the folded portion 16 at the center in the width direction (the cross-sectional view taken along line AA in FIG. 2). FIG. 3(b) shows a cross-sectional view of one side in the width direction of the folded portion 16 (the cross-sectional view taken along line BB in FIG. 2). As shown in these figures, the folded portion 16 is composed of a first plate-shaped portion 16a connected to the top surface portion 12, which forms the restriction area 13, a bent portion 16b connected to the first plate-shaped portion 16a, and a second plate-shaped portion 16c connected to the bent portion 16b. The second plate-shaped portion 16c extends in a different direction from the first plate-shaped portion 16a. In the folded portion 16 configured as described above, the thickness dimensions of each portion are set so that the thickness dimensions on both sides in the width direction are smaller than the thickness dimension at the center in the width direction.

[0021] In this embodiment, when the thickness dimensions of the first plate-shaped portion 16a, the bending portion 16b, and the second plate-shaped portion 16c at the widthwise center of the folded portion 16 are tc1, tc2, and tc3, respectively (see Figure 3(a)), and the thickness dimensions of the first plate-shaped portion 16a, the bending portion 16b, and the second plate-shaped portion 16c at one widthwise side are ts1, ts2, and ts3, respectively (see Figure 3(b)), the thickness dimensions tc2 and ts2 of each portion are set to predetermined sizes so that the thickness dimensions ts2 and ts3 of the bending portion 16b on both widthwise sides are smaller than the thickness dimensions tc2 and tc3 of the bending portion 16b at the widthwise center.

[0022] In this embodiment, the thickness dimensions tc1 and ts1 of the first plate-shaped portion 16a connected to the top surface portion 12 of the folded-back portion 16 and the thickness dimensions tc3 and ts3 of the second plate-shaped portion 16c are set to be the same across the entire width. Also, in this embodiment, the thickness dimensions tc1 and ts1 of the first plate-shaped portion 16a are set to be the same as the thickness dimension tu of the top surface portion 12.

[0023] The ratio ts2 / tc2 of the thickness dimensions of the bent portion 16b at the widthwise center of the folded portion 16 and at both widthwise sides can be set without any particular restrictions, but from the viewpoint of ensuring the rigidity at each portion while aiming for the stress distribution effect described above, it is preferable to set the thickness dimensions tc2, ts2 of each portion so that the ratio ts2 / tc2 of each thickness dimension is within the range of 0.3 or more and 0.6 or less.

[0024] Furthermore, based on the results of the thermal stress analysis described above, it is preferable that the ratio of the region that is relatively thick in the width direction in the folded portion 16 to the entire width direction is set to 10% or more and 25% or less. In this embodiment, as shown in Fig. 2, the width direction dimension W1 of the width direction central region that is relatively thick in the width direction in the bent portion 16b of the folded portion 16 is set to 10% or more and 25% or less, preferably 11% or more and 22% or less, of the entire width direction dimension W2 of the bent portion 16b.

[0025] As described above, in the resin tailgate outer upper 10 according to this embodiment, when thermal stress occurs in the restriction area 13, the thickness dimension ts2 on both sides of the widthwise direction of the folded portion 16 is set smaller than the thickness dimension tc2 at the widthwise center of the folded portion 16, which is the starting point of stress concentration. This configuration distributes stress from the relatively thicker region of the folded portion 16 to the relatively thinner region. This prevents stress from concentrating at the widthwise center of the folded portion 16 as much as possible, thereby suppressing the spread of the stress concentration area and, ultimately, the thermal distortion occurring in the restriction area 13. Therefore, the tailgate outer upper 10 according to this embodiment makes it possible to prevent, as much as possible, the occurrence of poor appearance, such as concave deformation, in the tailgate outer upper 10.

[0026] Although one embodiment of the present invention has been described above, the resin outer panel member according to the present invention can also have other configurations than those described above without departing from the spirit of the invention.

[0027] For example, in the above embodiment, the thickness dimension ts2 of the bent portions 16b on both widthwise sides of the folded portion 16 is set smaller than the thickness dimensions tc2, tc3 of the bent portion 16b at the center in the widthwise direction, but of course the thickness distribution that can be taken in the folded portion 16 is not limited to this. For example, the thickness dimensions ts2, ts3 of the bent portions 16b and (part of or the entire) the second plate-shaped portion 16c on both widthwise sides of the folded portion 16 may be set smaller than the thickness dimensions ts3, tc3 of the bent portion 16b and second plate-shaped portion 16c at the center in the widthwise direction. Alternatively, the thickness dimensions ts1, ts2, ts3 of the first plate-shaped portion 16a (part or all), the bending portion 16b, and the second plate-shaped portion 16c (part or all) on both sides of the folded portion 16 in the width direction may all be set smaller than the thickness dimensions tc1, tc2, tc3 of the first plate-shaped portion 16a, the bending portion 16b, and the second plate-shaped portion 16c at the center in the width direction.

[0028] In the above embodiment, an example was given in which the adhesive fixing portion 14 to the back door inner and the folded portion 16 are provided on the peripheral edge of the restriction area 13, and a predetermined thickness distribution is imparted to the folded portion 16, but of course the application of the present invention is not limited to this. For example, although not shown, in a back door outer upper 10 in which a portion fixed to the peripheral edge of the back door inner by a fixing means other than adhesion, such as welding, is provided on the peripheral edge of the restriction area 13, and the folded portion 16 is provided at a position sandwiching the fixed portion and the central portion 13a of the restriction area 13, the folded portion 16 may be imparted with the thickness distribution as described above.

[0029] Furthermore, although the above description has exemplified the case where the present invention is applied to the automobile back door outer upper 10, it is of course possible to apply the present invention to other panel parts. That is, the protrusion according to the present invention can be provided on any outer panel member, as long as the outer panel member forms the exterior of the vehicle together with the inner panel member and the fixed portion with the inner panel member and the folded portion are respectively provided at positions sandwiching the center of the restriction area. [Explanation of symbols]

[0030] 10 Back door outer upper 10a Periphery 11 Rear spoiler 12 Top section 12a Open side edge 13 Regulatory Area 13a central part 14 Adhesive fixing part 15 Bending section 16 Folded section 16a First plate-shaped portion 16b Bend part 16c Second plate-shaped part tc1, tc2, tc3 Thickness dimension (center of the folded part width direction) ts1, ts2, ts3 Thickness dimensions (both sides of the folded part in the width direction) tu Thickness (top surface) W1 Width dimension (thick area) W2 Overall width dimension

Claims

1. A resin outer panel member that constitutes an exterior portion of a vehicle together with an inner panel member, a restriction region in which stretching along the surface is restricted while a portion of the peripheral edge portion is fixed to the inner panel member; a folded portion provided at a position sandwiching a portion of the peripheral edge of the restriction area that is fixed to the inner panel member and a central portion of the restriction area, the folded portion being folded back toward the central portion of the restriction area; A resin outer panel member, wherein the thickness dimension of the folded portion on both sides in the width direction is set smaller than the thickness dimension of the folded portion at the width direction center side.

2. the folded portion is composed of a first plate-shaped portion connected to the restriction area, a bent portion connected to the first plate-shaped portion, and a second plate-shaped portion connected to the bent portion and extending in a direction different from that of the first plate-shaped portion, 2. The resin outer panel member according to claim 1, wherein the thickness of the folded portion on both sides in the width direction of the bent portion is set smaller than the thickness of at least a portion of the folded portion on a widthwise central side of the bent portion.

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