JP2011148419A - Bonnet hood structure body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonnet hood structure not having risk that it is locally caved, attaining short stroke of a crushable zone of the bonnet hood and attaining light weight. <P>SOLUTION: The bonnet hood structure body 10 comprises a skin layer 11 comprising an aluminum material; a reinforcement layer 12 arranged on a back surface of the skin layer 11 and comprising a material having elastic modulus of 20-130 GPa; and a middle layer 13 arranged between the reinforcement layer 12 and the skin layer 11 and comprising a material having elastic modulus of 0.01-6 GPa. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a structure suitable for a hood hood of a vehicle.

In recent years, reduction of carbon dioxide, which is a greenhouse gas, has been demanded worldwide. Under such circumstances, it is indispensable for automobiles to improve fuel consumption, and reduction of vehicle body weight and reduction of air resistance are indispensable.
On the other hand, from the viewpoint of pedestrian protection, it is required to provide the hood hood with performance for protecting pedestrian head injury.

  In order to reduce the weight of the vehicle body, the bonnet hood is replaced with a light metal such as an aluminum material from a steel plate to reduce the weight. However, since the inertial mass is reduced as the weight is reduced, the initial load is reduced and the energy absorption stroke is increased. Since the weight has been reduced, there is a concern that the performance of protecting the injury of the pedestrian head may be reduced.

In order to compensate for this, it has been proposed to increase the inertial mass by attaching various mass materials, that is, weights (see, for example, Patent Document 1).
However, the weight of the vehicle body increases as much as the weight is applied, so that weight reduction cannot be achieved.

Thus, a technique has been proposed in which a lifting device detects a pedestrian collision, lifts the hood, and forcibly increases the clearance between the hood and the engine (see, for example, Patent Document 2).
However, in order to lift the hood instantaneously, a high-speed actuator is required, and this high-speed actuator causes an increase in vehicle manufacturing cost and an increase in vehicle body weight.

Therefore, a sandwich structure in which a soft rubber is sandwiched between metal plates has been proposed (see, for example, Patent Document 3).
It is expected to absorb impact with soft rubber. However, if the form of the collision is limited to the local area, the local area will collapse, leading to breakage. That is, it is difficult to absorb energy as a whole.

  Therefore, there is a need for a hood structure that does not cause local depression, can shorten the crushable zone, and can reduce the weight.

JP-A-6-239268 JP 2006-290297 A Japanese Patent Laid-Open No. 5-220883

  An object of the present invention is to provide a hood structure for a hood that does not cause a local depression and that can shorten the stroke of the crushable zone and can be reduced in weight.

The invention according to claim 1 is a structure used for a hood hood of a vehicle,
This structure has a surface layer made of an aluminum material, a reinforcing layer that is arranged on the back surface of the surface layer and made of a material having an elastic modulus of 20 to 130 GPa, and an elastic modulus that is arranged between the reinforcing layer and the surface layer. And an intermediate layer made of a material of ˜6 GPa.
Bonnet hood structure.

The invention according to claim 2 is a structure used for a hood hood of a vehicle,
This structure has a surface layer made of a steel material having a thickness not exceeding 0.7 mm, a reinforcing layer made of a material having an elastic modulus of 20 to 130 GPa disposed on the back surface of the surface layer, and between the reinforcing layer and the surface layer. And an intermediate layer made of a material having an elastic modulus of 0.01 to 6 GPa.

  The invention according to claim 3 is characterized in that the intermediate layer is made of a resin composition, and the reinforcing layer is made of a metal or a resin.

  The invention according to claim 4 is characterized in that the reinforcing material is made of aluminum.

In the invention according to claim 1, the structure used for the hood of the vehicle includes an aluminum surface layer, a reinforcing layer having an elastic modulus of 20 to 130 GPa, and an intermediate layer having an elastic modulus of 0.01 to 6 GPa. The intermediate layer works to disperse the collision force and prevents the occurrence of local depression.
If the elastic modulus of the reinforcing layer is 20 to 130 GPa and the elastic modulus of the intermediate layer is 0.01 to 6 GPa, the short stroke and light weight required for the bonnet hood are achieved.

  In the invention according to claim 2, the structure used for the hood of the vehicle includes a steel surface layer of 0.7 mm or less, a reinforcing layer having an elastic modulus of 20 to 130 GPa, and an intermediate layer having an elastic modulus of 0.01 to 6 GPa. It consists of. Since the steel sheet has a large specific gravity, the increase in weight is suppressed by setting it to 0.7 mm or less.

The intermediate layer works to disperse the collision force and prevents the occurrence of local depression.
If the elastic modulus of the reinforcing layer is 20 to 130 GPa and the elastic modulus of the intermediate layer is 0.01 to 6 GPa, the short stroke and light weight required for the bonnet hood are achieved.

  In the invention which concerns on Claim 3, an intermediate | middle layer consists of a resin composition, and a reinforcement layer consists of a metal or resin. Resin is much lighter than steel and lighter than aluminum, a light metal. By adopting resin for the intermediate layer, the thickness of the intermediate layer can be increased, and by making the thickness to some extent, the collision force input to the surface layer can be dispersed in the intermediate layer, and the surface layer is locally There is no need to worry about being depressed.

  In the invention according to claim 4, the reinforcing material is made of aluminum. Carbon steel has a specific gravity of about 7.8, and aluminum has a specific gravity of 2.6. By adopting aluminum, weight reduction can be promoted.

It is sectional drawing of the bonnet food | hood structure which concerns on this invention. FIG. 4 is an acceleration / stroke diagram obtained by conducting an actual impactor collision test on an invention product and a conventional product. It is a correlation diagram of Comparative Examples 1-3 by an actual impactor collision test. It is a correlation diagram of comparative example 4 and examples 1 and 2 by an actual impactor collision test. It is a correlation diagram of a mini impactor impact test and an actual impactor impact test. It is a correlation diagram of the elasticity modulus of a reinforcement layer, and an energy absorption stroke. It is a correlation diagram of the elasticity modulus of a reinforcement layer, and the weight of a test material. It is a correlation diagram of the elasticity modulus of an intermediate | middle layer, and an energy absorption stroke. It is a correlation diagram of the elasticity modulus of an intermediate | middle layer, and the weight of a test material.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the hood hood structure 10 includes a surface layer 11 made of an aluminum material or a steel material, a reinforcing layer 12 made of a material having an elastic modulus of 20 to 130 GPa disposed on the back surface of the surface layer 11, and the reinforcement The intermediate layer 13 is disposed between the layer 12 and the surface layer 11 and made of a material having an elastic modulus of 0.01 to 6 GPa.

The surface layer 11 is required to have basic merchantability as an automobile such as appearance and smoothness. If it is a carbon steel plate, the thickness is preferably in the range of 0.4 to 0.8 mm. In the case of an aluminum plate (including an aluminum alloy plate), the thickness is preferably in the range of 0.5 to 1.5 mm.
When the plate thickness is less than the lower limit, it becomes difficult to press-mold and secure strength.
On the other hand, when the plate thickness exceeds the upper limit value, weight increase is caused and the pedestrian head injury value increases, which is not preferable.

  A tensile load acts on the reinforcing layer 12 when an impact force is applied to the surface layer 11 from the outside. It is required to exhibit energy absorption against the deformation accompanying this tension. If the elastic modulus is 20 to 130 GPa, energy is effectively absorbed. Examples of such materials include carbon steel, stainless steel, copper, titanium, magnesium, carbon, and synthetic resin (especially aromatic polyamide resin fiber).

  The intermediate layer 13 is required to have a function of dispersing this force over the entire hood when an impact force is applied to the surface layer 11 from the outside. If the elastic modulus is 0.01 to 6 GPa, the impact force is dispersed. Examples of such materials include thermosetting resins (epoxy resins, urethane resins, ester resins, and modified products thereof) and thermoplastic resins (polypropylene, ABS resin, nylon, and modified products thereof). It is done.

The specific gravity is 1.6 to 1.9 for epoxy resin, 1.8 to 2.3 for polyester-based fat, about 0.9 for polypropylene, about 1.0 for ABS resin, and about 1.1 for nylon.
The specific gravity of carbon steel is about 7.8, the specific gravity of aluminum is 2.6, and the resin is much lighter than steel and lighter than aluminum, which is a light metal.

  By adopting resin for the intermediate layer, the thickness of the intermediate layer can be increased, and by making the thickness to some extent, the collision force input to the surface layer can be dispersed in the intermediate layer, and the surface layer is locally There is no need to worry about being depressed.

Next, the operation of the hood hood structure 10 of the present invention having the above configuration will be described.
FIG. 2 is an acceleration / stroke diagram obtained by performing an actual impactor collision test on the invention and the conventional product. Although detailed test conditions will be described later, the initial peak acceleration of the invention is Ga and the stroke is Sa. It was. On the other hand, in the conventional product made of a carbon steel plate having a thickness of 0.4 mm, the initial peak acceleration Gb is smaller than Ga and the stroke Sb is larger than Sa.

  Since the acceleration of the invention is larger by (Ga-Gb) than that of the conventional product, the impact energy absorption performance can be improved. A large acceleration means that the rigidity is high (large). If the rigidity is high, the large-scale reinforcement as conventionally performed is unnecessary, and the structure of the hood hood can be simplified and lightened.

  In addition, since the stroke of the inventive product is smaller than that of the conventional product by (Sb-Sa), a short stroke in the crash bull zone can be realized, and the hood hood can be brought closer to the engine. By lowering the hood, the vehicle height can be lowered, the air resistance during vehicle travel can be lowered, and fuel efficiency can be improved.

  In order to clarify the difference between the above actions and effects, the present inventors conducted the following experiments.

(Experimental example)
Experimental examples according to the present invention will be described below. Note that the present invention is not limited to experimental examples.

○ Material:
In order to produce the test materials, the materials shown in the following table were prepared for the surface layer, the intermediate layer, or the reinforcement.

  Names are shown in the rightmost column of Table 1. The following description is advanced using this designation.

○ Mini impactor impact test:
Place a jig on the floor. And, □ 250mm (read as 250mm square. Length 250mm × width 250mm, the same applies hereinafter), each of the three in total, one place on the front side and 230mm on the rear side, two places on the rear side. Fix it horizontally to the jig with 6mm diameter flange bolts. The front and rear pitch was also 230 mm.
A natural rubber plate of 1 mm thickness and □ 50 mm is placed on the upper surface of the surface layer.

Next, from 3 m above, the mini impactor is dropped to the center of the specimen. At this time, the collision speed to the test material is 27.6 km / h.
The mini impactor includes an acceleration sensor (ASE-A-500SA5 manufactured by Kyowa Dengyo) at the rear end. For data sampling, EDX-11A manufactured by Kyowa Dengyo was used.

  The mini-impactor is a bullet body weighing 930 g (including an acceleration sensor, not including a harness), having a diameter of 40 mm and a spherical surface with a 20 mm radius at the tip, and is cut out from the S45C material.

○ Procedure for preparing test materials for mini impactor impact test:
The preparation procedures of the specimens used for the mini impactor impact test will be described for Comparative Examples 1 to 7 and Examples 1 to 8, respectively.

-Preparation of test material for Comparative Example 1:
A 0.7mm thick 270MPa class steel plate was pressed into a simple mold under vacuum pressure so as to obtain a reduced shape of the actual hood, and was plastically processed to a bending radius of 2000mm. The processed product was trimmed with a water jet (edge cutting). ) Processing is performed to obtain a □ 250 mm dome-shaped specimen.

-Preparation of test material for Comparative Example 2: A dome-shaped test material having a thickness of 0.4 mm steel is obtained in the same procedure as in Comparative Example 1.
-Preparation of test material for Comparative Example 3: In the same procedure as in Comparative Example 1, a dome-shaped test material with aluminum (AA6022) thickness of 1.0 mm is obtained.
-Preparation of test material for Comparative Example 4: In the same manner as in Comparative Example 1, a dome-shaped test material having an aluminum (AA6022) thickness of 2.0 mm is obtained.

-Preparation of test material for Comparative Example 5:
An intermediate layer (SBR 2.0 t) is bonded to the reinforcing material (aluminum 0.2 t) with an epoxy adhesive, and an upper layer (aluminum 1.0 t) is bonded to the intermediate layer (SBR 2.0 t) with an epoxy adhesive. Are joined together to produce a three-layer structure. This three-layer structure is heated to 40 ° C. to promote adhesion, pressed against a simple mold under vacuum pressure, plastically processed to a bending radius of 2000 mm, and trimmed with a water jet to give a □ 250 mm Obtain a dome-shaped specimen with a three-layer structure.
-Preparation of test material for Comparative Example 6: GF0.2t as reinforcing material, 2.0t of ABS resin as intermediate layer, other conditions are the same as in Comparative Example 5, and a dome with a three-layer structure of □ 250 mm Obtain a mold specimen.
-Preparation of test material for Comparative Example 7: SUS 0.2t for reinforcing material, 2.0t of PE resin for intermediate layer, other conditions are the same as for Comparative Example 5 and a dome with a three-layer structure of □ 250mm Obtain a mold specimen.

-Preparation of test material for Example 1:
An intermediate layer (ABS1.5t) is bonded to the reinforcing material (aluminum 2.0t) with an epoxy adhesive, and an upper layer (aluminum 1.0t) is bonded to the intermediate layer (ABS1.5t) with an epoxy adhesive. Are joined together to produce a three-layer structure. This three-layer structure is heated to 40 ° C. to promote adhesion, pressed against a simple mold under vacuum pressure, plastically processed to a bending radius of 2000 mm, and trimmed with a water jet to give a □ 250 mm Obtain a dome-shaped specimen.

-Preparation of test materials for Examples 2 to 8: After changing the materials as shown in the following table, a dome-shaped test material having a three-layer structure is obtained by the same process as in Example 1.

○ Actual impactor impact test:
Place a large jig on the floor.
□ 800 mm test material (manufacturing procedure will be described later) is horizontally fixed to a jig with a flange bolt of 6 mm diameter each at a total of three locations, one on the front side and two on the rear side with a pinch of 760 mm. The front-rear pitch was 690 mm.

  Next, according to the European legal test mode, a 3.5 kg impactor is caused to collide with the center of the specimen under the conditions of a collision angle of 50 ° and a collision speed of 35 km / h.

○ Procedure for preparing test materials for actual impactor impact test:
The preparation procedures of the specimens used for the actual impactor impact test will be described for Comparative Examples 1 to 4 and Examples 1 and 2, respectively.

-Preparation of test material for Comparative Example 1:
A 0.7mm thick 270MPa class steel plate is pressed into a simple mold under vacuum pressure so that it has the same shape as an actual hood, and is plastically processed to a bending radius of 7000mm, and this processed product is trimmed with a water jet. To give a □ 800 mm dome-shaped specimen.

-Preparation of test material for Comparative Example 2: A dome-shaped test material having a thickness of 0.4 mm steel is obtained in the same manner as in Comparative Example 1.
-Preparation of test material for Comparative Example 3: In the same manner as in Comparative Example 1, a dome-shaped test material having a thickness of 1.0 mm for aluminum (AA6022) is obtained.
-Preparation of test material for Comparative Example 4: In the same manner as in Comparative Example 1, a dome-shaped test material having an aluminum (AA6022) thickness of 2.0 mm is obtained.

-Preparation of test material for Example 1:
An intermediate layer (ABS1.5t) is bonded to the reinforcing material (aluminum 2.0t) with an epoxy adhesive, and an upper layer (aluminum 1.0t) is bonded to the intermediate layer (ABS1.5t) with an epoxy adhesive. Are joined together to produce a three-layer structure. This three-layer structure is heated to 40 ° C. to promote adhesion, pressed against a simple mold under vacuum pressure, plastically processed to a bending radius of 7000 mm, and trimmed with a water jet to □ 800 mm Obtain a dome-shaped specimen with a three-layer structure.

Preparation of test material for Example 2: A dome-shaped test material having a three-layer structure with a steel layer of 0.4 mm is obtained in the same manner as in Example 1.

  According to the European legal test mode, a 3.5 kg impactor is made to collide with the center of the specimen under the conditions of a collision angle of 50 ° and a collision speed of 35 km / h. A correlation diagram with acceleration was created.

It is a correlation diagram of Comparative Examples 1 to 3 by an impactor collision test, and as shown in (a), the initial peak acceleration in Comparative Example 1 was 126 G and the stroke was 115 mm.
In Comparative Example 2, as shown in (b), the initial peak acceleration is 80 G and the stroke is 126 mm. In Comparative Example 3, as shown in (c), the initial peak acceleration is 90 G and the stroke is 118 mm. there were.

  In (a) to (c), the area within the curve corresponds to the amount of energy absorbed. Since the impact test is in a constant mode, the amount of energy obtained by the impact test is constant, that is, the area in the curve is the same. The following figure is the same.

FIG. 4 is a correlation diagram between Comparative Example 4 and Examples 1 and 2 in an actual impactor collision test. As shown in FIG. 4A, the initial peak acceleration in Comparative Example 4 was 130 G and the stroke was 108 mm. .
In Example 1, as shown in (b), the initial peak acceleration is 122 G, and the stroke is 93 mm.
In Example 2, as shown in (c), the initial peak acceleration was 116 G, and the stroke was 101 mm.
The above initial peak acceleration and stroke can be summarized as follows.

Next, in Table 3 (that is, the actual impactor collision test), the reasons for omitting Examples 3 to 8 and Comparative Example 5 will be described.
About Comparative Examples 1-4 and Examples 1, 2, the value of the energy absorption stroke was extracted from Table 2 and Table 3, and the correlation was investigated. The results are shown in the following figure.
As shown in FIG. 5, a good correlation is recognized between the value in the mini impactor crash test shown on the horizontal axis and the value in the actual impactor test shown on the vertical axis. As described above, it was confirmed that the sufficient correlation was confirmed, so that the evaluation in the mini impactor collision test with a simple test could be performed. Accordingly, Examples 3 to 8 and Comparative Example 5 were omitted in the laborious actual impactor collision test.

Next, evaluation determination is performed on Table 2.
In Table 2, Comparative Example 1 (steel plate 0.7 t) is widely used for existing hood hoods. Therefore, the □ 250 weight (344 g) of Comparative Example 1 and the stroke (35 mm) are set as threshold values.

From the standpoint of improving fuel efficiency, □ is used for specimens whose weight exceeds 344 g, and ◯ for specimens that are less than 344 g. Further, from the viewpoint of energy absorption, a short stroke is required, and a specimen having a stroke exceeding 35 mm is marked as “x”, and a specimen having a stroke below is marked as “◯”. When there is x in one of the two kinds of evaluations, the comprehensive evaluation is x, and when both of the two kinds of evaluations have ◯, the comprehensive evaluation is ◯.
The results are shown in the following table.

The evaluation shown in the above table will be further analyzed.
For this analysis, the elastic modulus of the intermediate layer and the elastic modulus of the reinforcing layer are transferred from Table 1 to the bottom row of Table 4.
According to the knowledge of the present inventors, the elastic modulus of the reinforcing layer and the intermediate layer strongly affects the deformation performance and the energy absorption performance.
Therefore, we decided to investigate the correlation between elastic modulus, energy absorption stroke and weight.

As shown in FIG. 6, the correlation between the elastic modulus of the reinforcing layer and the energy absorption stroke was graphed. That is, the energy absorption stroke in Table 4 was taken on the horizontal axis, and the elastic modulus of the reinforcing layer in Table 4 was taken on the vertical axis.
A curve connecting points of Examples 1 to 8 and Comparative Examples 6 and 7 is A. The energy absorption stroke in Comparative Example 1 which is a conventional reference model is 35 mm. Since a short stroke is desired, a value of 35 mm or less on the horizontal axis is deemed “possible”. If the intersection of the straight line B raised from 35 mm and the curve A is C, the coordinates of this point C are (35, 20). In order to make the area “possible”, the vertical axis needs to be 20 GPa or more.

Further, as shown in FIG. 7, the correlation between the elastic modulus of the reinforcing layer and the weight of the test material (□ 250) was graphed. That is, the weight of □ 250 in Table 4 was taken on the horizontal axis, and the elastic modulus of the reinforcing layer in Table 4 was taken on the vertical axis. The weight of □ 250 in Comparative Example 1, which is a conventional reference model, is 344 g. Since weight reduction is desired, 344 g or less on the horizontal axis is defined as “OK”.
If the intersection of the straight line E raised from 344 g on the horizontal axis and the curve D is F, the coordinates of this point F are (344, 130). In order to make the area “possible”, the vertical axis needs to be 130 GPa or less.

  As explained above, if the elastic material has an elastic modulus in the range of 20 to 130 GPa, both a short stroke and a light weight can be achieved.

Next, as shown in FIG. 8, the correlation between the elastic modulus of the intermediate layer and the energy absorption stroke was graphed. That is, the energy absorption stroke in Table 4 was taken on the horizontal axis, and the elastic modulus of the intermediate layer in Table 4 was taken on the vertical axis.
The energy absorption stroke in Comparative Example 1 which is a conventional reference model is 35 mm. Since a short stroke is desired, a value of 35 mm or less on the horizontal axis is deemed “possible”. Assuming that the intersection of the straight line H raised from 35 mm on the horizontal axis and the curve G is J, the coordinates of this point J are (35, 0.007). In order to make the area “possible”, the vertical axis needs to be 0.007 GPa or more.

Moreover, as shown in FIG. 9, the correlation between the elastic modulus of the intermediate layer and the weight of the test material (□ 250) was graphed. That is, the weight of □ 250 in Table 4 was taken on the horizontal axis, and the elastic modulus of the intermediate layer in Table 4 was taken on the vertical axis. The weight of □ 250 in Comparative Example 1, which is a conventional reference model, is 344 g. Since weight reduction is desired, 344 g or less on the horizontal axis is defined as “OK”.
When the intersection of the straight line L raised from 344 g on the horizontal axis and the curve K is M and N, the coordinates of the point M are (344, 6). In order to make the area “possible”, the vertical axis needs to be 6 GPa or less.

  Further, the coordinates of the intersection N of the straight line L and the curve K are (344, 0.01). In order to make it a “possible” region, the vertical axis needs to be 0.01 GPa or more. This value is a value satisfying FIG.

  As described above, for the intermediate material, both a short stroke and a light weight can be achieved if the elastic modulus is in the range of 0.01 to 6 GPa.

  The present invention is suitable for a hood hood of a vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Bonnet food structure, 11 ... Surface layer, 12 ... Reinforcement layer, 13 ... Middle layer.

Claims (4)

A structure used for a hood of a vehicle,
This structure has a surface layer made of an aluminum material, a reinforcing layer that is arranged on the back surface of the surface layer and made of a material having an elastic modulus of 20 to 130 GPa, and an elastic modulus that is arranged between the reinforcing layer and the surface layer. A bonnet hood structure characterized by comprising an intermediate layer made of a material of -6 GPa. A structure used for a hood of a vehicle,
This structure has a surface layer made of a steel material having a thickness not exceeding 0.7 mm, a reinforcing layer made of a material having an elastic modulus of 20 to 130 GPa disposed on the back surface of the surface layer, and between the reinforcing layer and the surface layer. A bonnet hood structure comprising: an intermediate layer that is disposed and made of a material having an elastic modulus of 0.01 to 6 GPa.   The hood hood structure according to claim 1 or 2, wherein the intermediate layer is made of a resin composition, and the reinforcing layer is made of metal or resin.   The hood hood structure according to claim 1, wherein the reinforcing material is made of aluminum.

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