JP2007118852A - Vehicle hood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle hood structured so that an outer panel and an inner panel formed from materials having different coefficients of linear expansion are adhered fast, capable of preventing the outer panel from slipping off owing to differing linear expansion. <P>SOLUTION: The vehicle hood is composed of the outer panel 1, the inner panel 2 adhered fast to the outer panel, and a bracket 3 adhered fast to both the inner panel and the outer panel in such a manner as covering at least part from the outside edge of the outer panel to the inner panel on its side with the outside edge of the outer panel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an automobile hood.

  In recent years, studies have been made on reducing the weight of automobile materials as a measure for reducing exhaust gas emissions into the environment, and various FRP (fiber reinforced plastics) are being studied for automobile hoods. For example, Patent Document 1 discloses a structure in which an FRP outer panel and an FRP inner panel are bonded and fixed with an adhesive. In addition, considering cost reduction by increasing the degree of freedom of material selection and rationalizing the production process, if the optimum material can be used for each component without restrictions on the material side, the degree of freedom of design can be expanded. I can expect. In other words, taking an automobile hood as an example, it is possible to design the outer panel and the inner panel to be made of different materials suitable for each. However, there are the following problems in bonding different materials. The use of different materials in combination with structural members has not been put to practical use.

  As general knowledge about the adhesion of different materials, the linear expansion coefficient is often different for different materials, and there is a possibility that adhesion peeling due to the shear stress generated on the bonding surface 7 occurs due to the difference in linear expansion. When the adhesive length L is increased as shown in FIG. 6 (L <La), even if the adhesive starts plastic deformation at the outer edge of the adhesive, the portion with a small shear stress at the center becomes elastic deformation, and the elastic deformation portion When it is large, there is a knowledge that a force to return plastic deformation acts to prevent breakage (see Non-Patent Document 1). However, in the case where the automobile hood is assumed as shown in FIG. 7, the hat-shaped cross section of the inner panel 2 moves to the inside of the vehicle and moves above the engine and chassis parts existing on the lower side of the hood vehicle. This is a major limitation in automobile design. That is, in the pedestrian head protection that is currently a problem, the bottom surface of the hat-shaped cross section of the inner panel 2 and these engine parts, etc., so that the pedestrian's head does not collide with the engine or chassis parts after colliding with the hood. In many cases, it is difficult to take such a mode. Furthermore, there is a concern that the weight of the hood and the cost will increase due to an increase in the amount of adhesive used.

In Non-Patent Document 1, etc., it is said that the adhesive thickness, adhesive properties, etc. necessary to prevent adhesive breakage in bonding of members having different linear expansion coefficients are required. The design based only on the adhesive thickness and adhesive properties required from the above-mentioned literature cannot be employed in automobile hoods and the like that are not limited to being opened / closed and deformed by aerodynamics over many years.
JP 2003-145628 A Hart-Smith, LJ, Adhesively-Bonded Double-Lap Joints (Jan., 1973), NASA Technical Report 112235

  There are the following problems in bonding an outer panel and an inner panel made of materials having different linear expansion coefficients.

  That is, shear stress as shown in FIG. 5 is generated on the bonding surface 7 due to the difference in linear expansion between the outer panel and the inner panel formed of materials having different linear expansion coefficients. Further, it is known that the shear stress increases as it goes to the outer edge of the outer panel 1 or the inner panel 2. The adhesive is deformed by the shear stress, and when the shear stress exceeds a certain value, the adhesive starts plastic deformation, and when the deformation progresses and exceeds the breaking elongation, the adhesive breaks. In the worst case, when the adhesive breaks over the entire circumference of the hood, the outer panel 1 may fall off the inner panel 2 when the vehicle is running, and may collide with another vehicle or a pedestrian.

  The object of the present invention is to prevent breakage due to shear stress generated on the bonding surface 7 due to the difference in linear expansion between the outer panel 1 and the inner panel 2, and in the event that all of the adhesive joining the outer panel 1 and the inner panel 2 is broken. Even in such a case, the object is to provide an automobile hood structure that can prevent the outer panel 1 from falling off the inner panel 2.

In order to solve the above problems, the present invention has the following configuration. (1) The outer panel, the inner panel bonded and fixed to the outer panel, and the inner panel so as to cover at least a part of the outer panel from the outer edge of the outer panel to the outer edge of the outer panel. An automobile hood comprising a bracket bonded and fixed to both outer panels.

  (2) An outer panel, an inner panel bonded and fixed to the outer panel, and an outer panel bonded to the outer panel so as to cover at least a part of the inner panel on the outer edge side of the outer panel. An automobile hood comprising a fixed bracket and having an elastic body between the bracket and the inner panel.

  (3) The automobile hood according to any one of (1) and (2), wherein the outer panel and the bracket are made of a material having substantially the same linear expansion coefficient.

  (4) The automobile hood according to any one of (1) to (3), wherein the inner panel is made of a material having a linear expansion coefficient different from that of the outer panel and the bracket.

  (5) The automobile hood according to any one of (1) to (4), wherein the bracket is provided over the entire circumference of the outer edge portion of the outer panel.

  (6) The automobile hood according to any one of (1) to (4), wherein the bracket is cut and divided at a corner portion.

  (7) The automobile hood according to any one of (1) to (6), wherein an adhesive strength between the bracket and the outer panel is equal to or higher than a material strength of the bracket and the outer panel.

  (8) The automobile according to any one of (1) to (7), wherein an adhesive thickness of a portion where the outer panel and the inner panel are bonded and fixed is a thickness obtained from the following formula (I): For food.

(Α1-α2) / (4τpη (γe / 2 + γp) / E0t0) ^ 0.5 (I)
Α1: Linear expansion coefficient of the outer panel α2: Linear expansion coefficient of the inner panel τp: Yield stress of the adhesive
η: thickness of adhesive
γe: Plastic strain of adhesive γp: Breaking strain of adhesive E0: Elastic modulus of the inner panel t0: Thickness of the inner panel (9) The distance between the outer edge of the inner panel and the inner edge of the bracket The automobile hood according to any one of (1) to (8), wherein the hood is larger than a linear expansion difference between the outer panel and the inner panel.

  According to the automobile hood structure of the present invention, by setting a bracket on the outer edge of the hood, it is possible to prevent adhesive breakage due to shear stress acting on the adhesive surface from the difference in linear expansion between the outer panel and the inner panel, and the outer panel. Can be prevented from falling off from the inner panel.

  The automobile hood of the present invention will be described with reference to FIGS.

  As shown in FIG. 2, the automobile hood of the present invention includes an outer panel 1 that constitutes the outer surface of the vehicle body, an inner panel 2 disposed inside the outer panel 1, an outer edge portion of the outer panel 1, and an inner panel. It is comprised with the bracket 3 which can fix the outer edge part of the panel 2. As shown in FIG.

  The outer panel 1 is usually made of metal, resin or FRP. Here, when the cost reduction is important for the automobile hood, a metal hood, particularly a steel hood is applied. On the other hand, when importance is attached to weight reduction for improving fuel efficiency, aluminum, resin, or FRP is applied.

  Here, the product made of FRP means a resin reinforced with reinforcing fibers, and examples of the reinforcing fibers include reinforcing fibers made of inorganic fibers such as carbon fibers and glass fibers, and organic fibers such as Kevlar fibers, polyethylene fibers, and polyamide fibers. Fiber. Examples of the FRP matrix resin include thermosetting resins such as epoxy resins, unsaturated polyethylene resins, vinyl ester resins, and phenol resins, and further polyamide resins, polyolefin resins, dicyclopentadiene resins, polyurethane resins, and the like. A thermoplastic resin can also be used. Further, the mechanical properties of FRP can be appropriately set depending on the selection and combination of the reinforcing fibers and the matrix resin as described above, the orientation and volume content of the reinforcing fibers, and the laminated structure.

  Further, the FRP outer panel 1 includes an FRP single plate structure and a sandwich structure in which a core material is interposed between FRP single plates. Here, as the core material, an elastic body, a foam, or a honeycomb material can be used. The material of the foam is not particularly limited, and for example, a foam material made of a polymer material such as polyurethane, acrylic, polystyrene, polyimide, vinyl chloride, or phenol can be used. The honeycomb material is not particularly limited, and for example, aluminum alloy, paper, aramid paper or the like can be used.

  As described above, there are various options for the outer panel 1 of the automobile hood. However, it is possible to reduce the weight, and since there are various design means for securing surface rigidity with respect to various hood design surfaces, an optimum structure is provided. Since it is easy to take, the thing made from FRP is preferable.

  Examples of the inner panel 2 include those made of metal, resin, or FRP. The inner panel 2 has a hat-shaped cross section to ensure hood rigidity (bending, torsion, etc.). By adjusting the size and thickness of the hat cross section, the necessary rigidity for the hood should be ensured. Therefore, the design of the material of the inner panel 2 is possible even if the above-mentioned materials are used. Among these, aluminum is preferable in consideration of cost, weight reduction, and productivity.

  As a combination of the outer panel 1 and the inner panel 2, it is preferable to combine a product made of FRP preferable as the outer panel 1 and a product made of aluminum preferable as the inner panel 2.

  Conversely, the outer panel 1 may be made of aluminum and the inner panel 2 may be made of FRP. In this case, for example, when the design of the hood after painting is regarded as important, since the metallic luster of the outer panel 1 is superior, it is preferably employed when such characteristics are important. be able to. In that case, the inner panel 2 can be made of an FRP having a wide variety of design means in order to reduce the weight and increase the rigidity.

  As shown in FIG. 1, the outer panel 1 and the bracket 3 are bonded and fixed with an adhesive 4 at an outer edge portion of the outer panel 1. The outer edge portion of the inner panel 2 is bonded and fixed to the outer panel 1 and the bracket 3 with an adhesive 5.

  At this time, the adhesive 4 and the adhesive 5 in FIG. 1 are not limited to the same one. In general, the adhesive 4 or the adhesive 5 is preferably one having a certain degree of elasticity, and urethane type, epoxy type, phenol type and the like can be applied, and among them, a urethane type adhesive is preferable.

  The outer panel 1 and the bracket 3 are preferably formed of materials having substantially the same linear expansion coefficient. Since the outer panel 1 and the bracket 3 are formed of materials having substantially the same linear expansion coefficient, the adhesion between the outer panel 1 and the bracket 3 can be prevented from being broken by thermal expansion. This is because even if the bonded portion of the panel 2 and / or the bonded portion of the outer panel 1 and the inner panel 2 is broken, the outer panel 1 can be prevented from falling off the inner panel 2.

  The inner panel 2 is preferably formed of a material having a coefficient of linear expansion different from that of the outer panel 1 and the bracket 3. By configuring the outer panel 1 and the bracket 3 with materials having different linear expansion coefficients, the outer panel 1 can be made of FRP, the inner panel 2 can be made of aluminum, and the weight can be reduced. This is preferable because the cost can be reduced by improving the performance.

  Here, the fact that the linear expansion coefficients are substantially the same means that the difference in the normal linear expansion coefficients is within 2%. This is because the elongation at which plastic deformation of the urethane adhesive usually used as the adhesive 4 occurs is 2%.

  As shown in FIG. 2, the bracket 3 has a shape that is provided over the entire periphery of the outer edge of the outer panel 1 or a shape that is provided only in a part of the outer periphery, for example, 3a in FIG. A shape obtained by cutting and dividing at such a corner portion can be given.

  It is preferable that the bracket has a shape provided over the entire periphery of the outer edge portion of the outer panel 1 because the rigidity of the outer edge portion of the hood can be increased.

  By using the cut and divided bracket 3a, the mold necessary for manufacturing the bracket 3 can be reduced in size, and the cost can be reduced. Also, the weight of the bracket and the weight of the adhesive used can be reduced.

  An adhesive is used such that the adhesive strength of the adhesive 5 that bonds and fixes the outer panel 1 and the bracket 3 is equal to or higher than the material strength of the outer panel 1 and the bracket 3.

  The bonding thickness (t1 in FIG. 1) between the outer panel 1 and the inner panel 2 in the present invention is not particularly limited, but Hart-Smith thermal mismatch (α1-α2) / (4τpη (γe / 2 + γp) / It is preferable that the thickness is derived from (E0t0) ^ 0.5 (I). By satisfying the formula (I), it is possible to suppress breakage from the shear stress acting on the adhesive surface against the shear stress concentration generated at the adhesive portion of the hood outer edge.

  Also, the adhesive thickness t2 between the inner panel 2 and the bracket 3 is preferably the same as that derived from (I) above for the same reason.

  For example, when carbon fiber reinforced plastic is used for the outer panel 1 and the bracket 3, aluminum is used for the inner panel 2, and urethane adhesive is used for the adhesives 4 and 5, the adhesive thicknesses t 1 and t 2 require 3 mm.

  In FIG. 1, the distance t3 between the outer edge portion of the inner panel 2 and the inner edge portion of the bracket 3 is preferably larger than the linear expansion difference between the outer panel 1 and the inner panel 2, thereby preventing interference due to the linear expansion difference. .

For example, for a 1 m hood, carbon fiber reinforced plastic (linear expansion coefficient 0 × 10 ⁻⁶ / ° C.) for the outer panel 1 and bracket 3 and aluminum (linear expansion coefficient 3 × 10 ⁻⁶ / ° C.) for the inner panel 2. ), The deformation amount of the inner panel 2 is 3 mm larger than the deformation amount of the outer panel 1 when the operating environment temperature difference is 100 degrees. Therefore, by setting the gap t3 between the inner panel 2 and the bracket 3 to be larger than 1.5 mm, it is possible to prevent interference due to a difference in linear expansion between the inner panel 2 and the bracket 3.

  In the present invention, as shown in FIG. 4, an elastic body 6 can be used instead of the adhesive between the outer edge portion of the inner panel 2 and the bracket 3.

  By using the elastic body 6, it is possible to improve the appearance of the adhesive protruding from the inner panel 2 and the bracket 3, and to eliminate the work of scooping out the protruding adhesive with a spatula or the like in order to improve the appearance normally. . Examples of the elastic body 6 that can be preferably used for this purpose include an EPDM (ethylene-propylene-diene terpolymer) sponge.

  Even if all the bonded portions of the outer panel 1 and the inner panel 2 and the inner panel 2 and the bracket 3 are broken by the structure of the present invention due to the bonding portion of the bracket 3 and the inner panel 2 or the presence of the elastic body fixing portion. The outer panel 1 can be prevented from falling off the inner panel 2.

  In addition, the inner panel 2 interferes with the bracket 3 due to the gap t3 between the outer panel 1 and the inner panel 2 being larger than the linear expansion difference between the outer panel 1 and the inner panel 2 due to the deformation direction due to the linear expansion of the outer edge portion of the inner panel 2. Can be prevented.

  By adopting this structure, it becomes possible to minimize the bonding length between the outer panel 1 and the inner panel 2, and the hood weight and cost increase can be suppressed.

  The hat-shaped cross section of the inner panel 2 can be arranged on the outer side of the vehicle as much as possible, and a gap between the engine and other parts and the hat-shaped cross-section bottom portion of the inner panel 2 is easily secured.

It is an adhesion section sectional view (AA) of a hood structure for cars of the present invention. It is a perspective view of the automobile hood of the present invention. It is a perspective view of another shape of the bracket component in the present invention. It is another adhesion part sectional view (AA) of the hood structure for cars of the present invention. It is a shear stress figure which acts on the adhesion surface in a prior art. It is a shear stress figure which acts on the adhesion surface at the time of enlarging the adhesion surface length in a prior art. It is hood inner sectional drawing (AA) at the time of enlarging an adhesion surface length.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer panel 2, 2a Inner panel 3, 3a Bracket * Adhesive 6 Elastic body 7 Bonding surface 8 Engine part or chassis part

Claims (9)

  An outer panel, an inner panel bonded and fixed to the outer panel, and the inner panel and the outer panel so as to cover at least a part of the outer panel from the outer edge of the outer panel. An automobile hood characterized by comprising brackets that are bonded and fixed to both sides.   An outer panel, an inner panel that is bonded and fixed to the outer panel, and an outer panel that is bonded and fixed to the outer panel so as to cover at least a part of the outer panel from the outer edge of the outer panel. An automobile hood comprising a bracket and having an elastic body between the bracket and the inner panel.   The automobile hood according to claim 1, wherein the outer panel and the bracket are made of a material having substantially the same linear expansion coefficient.   The said inner panel is a material of the linear expansion coefficient different from the said outer panel and the said bracket, The hood for motor vehicles in any one of Claims 1-3 characterized by the above-mentioned.   The automobile hood according to any one of claims 1 to 4, wherein the bracket is provided over the entire circumference of the outer edge of the outer panel.   The automobile hood according to any one of claims 1 to 4, wherein the bracket has a shape cut and divided at a corner portion.   The automobile hood according to claim 1, wherein an adhesive strength between the bracket and the outer panel is equal to or higher than a material strength of the bracket and the outer panel. The automobile hood according to any one of claims 1 to 7, wherein an adhesion thickness of a portion where the outer panel and the inner panel are bonded and fixed is a thickness obtained from the following formula (I).
(Α1-α2) / (4τpη (γe / 2 + γp) / E0t0) ^ 0.5 (I)
Α1: Linear expansion coefficient of the outer panel α2: Linear expansion coefficient of the inner panel τp: Yield stress of the adhesive
η: thickness of adhesive
γe: Plastic strain of adhesive γp: Breaking strain of adhesive E0: Elastic modulus of the inner panel t0: Thickness of the inner panel   The automobile hood according to any one of claims 1 to 8, wherein an interval between an outer edge portion of the inner panel and an inner edge portion of the bracket is set larger than a linear expansion difference between the outer panel and the inner panel. .

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