Panel made of synthetic resin for automobile

Abstract: A hood or trunk lid (1) is a blow-molded article and includes an outer skin (2) and a stiffener (3) integral with the outer skin. The stiffener (3) has an indentation-like molded portion (4,5) which extends in a widthwise direction of a vehicle body and protrudes toward the outer skin (2). A ridge (5) of the indentation is spaced apart from the outer skin (2), so that the hood or trunk lid (1) is folded from a start point (5) provided by the indentation (4) by a shock force from a collision.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to a panel made of a synthetic resin for an automobile, and particularly, to a hood or trunk lid which is blow-molded and which includes an outer skin and a stiffener integral with the outer skin, and a process for producing such a body panel. Description of the Prior Art: The present application has previously proposed a bonnet (hood) as such type of a panel (see JP-04-120015-A and JP 06 008 309 A). Such a bonnet has a closed-sectional structure and hence, has a sufficient rigidity for practical use. JP 06 008 309 A shows a body panel according to the preamble of claim 1. It is desirable for the bonnet to be formed so that when the automobile collides against another object, the bonnet folds or collapses by the shock force produced by the collision while overcoming its rigidity, and to absorb some of the shock force. SUMMARY OF THE INVENTION It is an object of the present invention to provide a panel made of a synthetic resin for an automobile, which is sufficiently rigid for practical use and which is formed so that it easily folds or collapses upon collision of the automobile. To achieve the above object, according to the present invention, there is provided a body panel of claim 1 and a method of manufacture of a body panel according to claim 18. This body panel can be used as a hood or a trunk lid made of a synthetic resin for an automobile, which is a blow-molded article and comprises the outer skin, and the stiffener integral with the outer skin, wherein the stiffener has the elongated indentation or tub-like molded portion which extends in a widthwise direction of a vehicle body and protrudes toward the outer skin. A ridge of the elongated indentation is spaced apart from the outer skin, so that the panel is configured to be folded from a start point provided by the tub-like molded portion by a shock force from the front or rear of the vehicle body. The panel has a closed-sectional structure, and therefore has a rigidity which is sufficient for practical use on an automobile body. On the other hand, when the automobile collides against another object, stress caused by the shock force is concentrated onto the elongated indentation of the stiffener, because the elongated indentation is spaced apart from the outer skin and is brittle. This causes the bonnet to be easily folded or collapsed into an angle shape from a start point provided by the elongated indentation. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the subject mater of the present invention, reference should be made to the accompanying drawings, wherein: Fig. 1 is a plan view of a hood or bonnet according to an embodiment of the invention; Fig. 2 is an enlarged sectional view taken along a line 2-2 in Fig. 1; Fig. 3 is a back view of the hood or bonnet shown in Fig. 1; Fig. 4 is an enlarged perspective view of a portion indicated by arrow 4 in Fig. 3; and Fig. 5 is an illustration for explaining the folding or collapsing of the bonnet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT For convenience and clarity, the term "bonnet" will be used throughout this description. It should be understood, however, that the bonnet described in Figures 1-5 could be an automobile hood or trunk lid, or other panel of an automobile to which the inventive characteristics are appropriate. In Figs. 1 to 3, a bonnet 1 is a blow-molded panel for an automobile, made of synthetic resin. The panel includes outer skin 2, and stiffener 3 integral with the outer skin 2, and has a closed-sectional structure. Each of outer skin 2 and stiffener 3 are formed from a synthetic resin selected from, for example, nylon-based polymer alloy, ABS, polyethylene, polypropylene, or other suitable material. Stiffener 3 is molded with an elongated indentation 4 which is angle-shaped in section, which extends over the substantially entire length in a widthwise direction b or of a vehicle body at a central portion of the stiffener 3 in a longitudinal direction a of the vehicle body, and which extends from an inner surface of stiffener 3 toward outer skin 2. The elongated indentation has an inner edge or ridge 5 which is spaced at a distance c apart from the outer skin 2. The stiffener 3 has a large number of semi-spherical shell-like reinforcing lugs 6 which are disposed over the substantially entire area of the stiffener 3 and protrude toward the outer skin 2, and a top 7 of each of the lugs 6 is fused to the outer skin 2. In this case, each of the reinforcing lugs 6 and the elongated indentation 4 do not intersect each other, thereby ensuring a rigidity enhancing effect provided by each reinforcing lug 6. The stiffener 3 also has four reinforcing ribs 8 which are semicircular in cross section and which protrude toward the outer skin 2. A ridge 9 of each of the reinforcing ribs 8 is fused to the inner surface of the outer skin 2. The two reinforcing ribs 8 extend in the widthwise direction b of the vehicle body at a rear edge of the stiffener 3, and the two other reinforcing ribs 8 extend from near ends of the two first reinforcing ribs 8 in the widthwise direction b of the vehicle body to intersect the elongated indentation 4, as shown in Figs. 1, 3 and 4. The fusing of each reinforcing lug 6 as well as each reinforcing rib 8 and the outer skin 2 is performed when the bonnet is molded. The bonnet 1 has a sufficient rigidity for practical use, because it has the closed-sectional structure and includes the plurality of reinforcing lugs 6 and the reinforcing ribs 8. When the automoblie 10 collides against another object in a state shown by a solid line in Fig. 5, stress caused by the shock force of the impact is concentrated onto the elongated indentation 4, because the elongated indentation 4 of the stiffener 3 is spaced apart from the outer skin 2, and is brittle. The elongated indentation 4 therefore functions as a "weak spot", and therefore acts as a point of collapse of the bonnet. This configuration causes the bonnet 1 to be easily folded into an angle shape from a start point provided by the elongated indentation 4, as shown by a dashed line in Fig. 5. Thus, the shock force produced by the collision can be absorbed. To permit the bonnet 1 to be reliably folded or collapsed in this manner, it is also desirable that the vertical angle of the elongated indentation 4 is in a range of ≤ 90°. According to the present invention, it is possible to provide a panel made of a synthetic resin for an automobile which is used as a bonnet or a trunk lid and has a rigidity sufficient for practical use and which is cappable of absorbing a shock force upon frontal collision or rear-end collision of the automobile by constructing the panel in the above-described manner. A hood or trunk lid is a blow-molded article and includes an outer skin and a stiffener integral with the outer skin. The stiffener has an elongated indentation which extends in a widthwise direction of a vehicle body and protrudes toward the outer skin. A ridge of the elongated indentation is spaced apart from the outer skin, so that the hood or trunk lid is folded from a start point provided by the elongated indentation by a shock force from a collision.

Claims: A body panel for an automobile, said body panel comprising: an outer skin (2), a stiffener (3) integral with said outer skin defining a closed-sectional structure, the interior surfaces of said structure defining the inner surfaces of said outer skin (2) and of said stiffener (3), and at least one reinforcing rib (8) extending from an inner surface of said stiffener toward the inner surface of said outer skin, with an inner surface of said at least one reinforcing rib being fused to said inner surface of said outer skin, whereby said at least one reinforcing rib (8) has a length which is greater than the width thereof, characterized in that said body panel further comprises an elongated indentation (4) which is integral with said stiffener and extending in a widthwise direction (b) of an automobile, said elongated indentation (4) having a first surface and a second surface extending toward said inner surface of said outer skin, said first surface and said second surface forming an angle () between each other, with an innermost edge (5) between the first and second surfaces being separated from said inner surface of said outer skin (2) by a gap (c), said elongated indentation (4) intersecting said at least one reinforcing rib (8), and that said outer skin and said stiffener are configured to be folded along said elongated indentation based upon a shock force on the body panel. A body panel as recited in claim 1, further comprising a plurality of reinforcing lugs (6) integrally formed on said stiffener (3), said lugs extending from said inner surface of said stiffener toward said inner surface of said outer skin (2), with an inner surface of each of said reinforcing lugs being fused to said inner surface of said outer skin. A body panel as recited in claim 1, wherein said at least one reinforcing rib (8) has a semi-circular cross section. A body panel as recited in claim 1, wherein said panel comprises a trunk lid, and wherein said outer skin and said stiffener are configured to collapse along said elongated indentation (4) based upon a shock force from a rear of the automobile. A body panel as recited in claim 1, wherein said panel comprises an automobile hood, and wherein said outer skin and said stiffener are configured to collapse along said elongated indentation (4) based upon a shock force from a front of the automobile. A body panel as recited in claim 1, wherein an air gap is disposed between the inner surface of the outer skin and the inner surface of the stiffener. A body panel as recited in claim 1, wherein said angle () is not greater than 90°. A body panel as recited in claim 1, wherein said at least one reinforcing rib (9) extends at least partially in the widthwise direction (b) of the vehicle body. A body panel as recited in claim 1, wherein said elongated indentation is disposed in a longitudinally central portion of the outer skin, and laterally extends along a substantially entire width of the outer skin. A body panel as recited in claim 1, wherein said outer skin, said stiffener, and said elongated indentation comprise a nylon-based polymer alloy. A body panel as recited in claim 1, wherein said outer skin, said stiffener, and said elongated indentation comprise an ABS plastic. A body panel as recited in claim 1, wherein said outer skin, said stiffener, and said elongated indentation comprise polyethylene. A body panel as recited in claim 1, wherein said outer skin, said stiffener, and said elongated indentation comprise polypropylene. A body panel as recited in claim 1, wherein said at least one reinforcing rib is a pair of reinforcing ribs (8) extending at inclinations with respect to a longitudinal direction of said vehicle body to be distanced larger from each other at front or rear ends thereof than at the other end. A body panel as recited in claim 14, comprising a pair of further reinforcing ribs (8) which are provided so as to extend in an aligned manner substantially along the widthwise direction (b) of the vehicle body with a spacing therebetween. A body panel as recited in claim 1, comprising a further reinforcing rib (8) which is formed at a position on said body panel that is near a compartment of said automobile. A body panel as recited in claim 15, wherein said further reinforcing ribs (8) are formed at positions on said body panel that are near a compartment of said automobile. A method of manufacturing an automobile body panel comprising an outer skin (2) and a stiffener (3) integral with said outer skin defining a closed-sectional structure, the interior surfaces of said structure defining the inner surfaces of said outer skin (2) and of said stiffener (3), said stiffener including an elongated indentation (4) integral with said stiffener and extending in a widthwise direction (b) of an automobile body, said elongated indentation (4) having a first surface and a second surface extending toward said inner surface of said outer skin, said first surface and said second surface forming an angle () between each other, with an innermost edge (5) between the first and second surfaces being separated from said inner surface of said outer skin (2) by a gap (c), and at least one reinforcing rib (8) extending from an inner surface of said stiffener toward the inner surface of said outer skin, with an inner surface of said at least one reinforcing rib being fused to said inner surface of said outer skin and intersecting said elongated indentation (4), whereby said at least one reinforcing rib (8) has a length which is greater than the width thereof, said method comprising the steps of: providing a mold for the body panel, said mold including mold elements to form said outer skin (2), said stiffener (3), said elongated indentation (4) and said at least one reinforcing rib (8); blow-molding a mold material into said mold; and removing the automobile body panel from said mold, thereby providing a body panel which is configured to be collapsed at a start point provided by said elongated indentation (4) based upon a shock force on the body panel. A method as recited in claim 18, wherein said mold material comprises a nylon-based polymer alloy. A method as recited in claim 18, wherein said mold material comprises an ABS plastic. A method as recited in claim 18, wherein said mold material comprises polyethylene. A method as recited in claim 18, wherein said mold material comprises polypropylene.

Inventors: CHIRIFU TAKASHI, HARADA TOSHIYUKI, ISHIBASHI MASATO, CHIRIFU, TAKASHI, HARADA, TOSHIYUKI, ISHIBASHI, MASATO
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: B62D29
IPC codes: B62D25, B62D29, B29C49, B29L31, B62D21, B29L22