JP2000071908A - Shock absorbing structure and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorbing structure for absorbing a shock by use of a plurality of ribs having height below 35 mm, showing a shock absorbing characteristic suitable for the protection of an occupant's head and the application thereof, and a concept for efficiently designing a rib structure. SOLUTION: This shock absorbing structure absorbs a shock by use of a plurality of ribs having height below 35 mm, and a rib strength index P defined by the formula P=N×t×S is 10 mm2 to 35 mm2. In the formula, N is a value (1/mm) resulting from the division of the number of rib intersections present in an effective range Q by total rib length (L1, L2 or the like), (t) is the mean thickness (mm) of ribs present in the effective area Q, S is the mean value (mm2) of rib cross sectional areas present in effective area Q and Q is an area inside a circle having a radius (mm) with a shock point as a center. Also, R is defined by the formula of R=0.85×h+40.1, where (h) is rib height (mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing structure for absorbing a shock with a plurality of ribs and its use. In detail, it is used for interior parts of automobiles, such as the pillar garnish inside the front pillar and center pillar, and does not damage the head when the occupant's head collides due to vehicle collision or rollover And a shock absorbing structure suitable for protecting the head.

[0002]

2. Description of the Related Art In recent years, in vehicles such as automobiles, in order to ensure a higher level of protection of occupants in the passenger compartment, increasingly higher standards have been set for occupant protection measures and the like. Among them, automotive interior parts that are likely to collide with the occupant's head, such as a pillar garnish that covers the inside of the vehicle interior of various pillars such as a front pillar, a center pillar, and a rear pillar, and a roof side garnish that covers a roof side rail, etc. Therefore, better impact energy absorption characteristics are required. In order to satisfy this requirement, Japanese Patent Application Laid-Open No. H8-119047 discloses that lattice-shaped ribs are arranged on these interior parts.

However, in the above publication, it was not always clear what kind of rib shape factors, such as rib thickness and lattice spacing, would provide impact absorption characteristics suitable for protecting the occupant's head. Therefore, trial and error is required in designing the rib structure, and a great amount of time is required.

Japanese Patent Laid-Open Publication No. Hei 10-35372 discloses that, in order to obtain a shock absorbing characteristic suitable for protecting the head of an occupant, in addition to arranging grid-like ribs on interior parts, a unit area is increased. The volume V / A of the rib group per unit is 1.
It is disclosed that the thickness is set to 48 mm ³ / mm ² or more.

[0005]

SUMMARY OF THE INVENTION However, the present invention
As a result of new studies, the V / A was set to 1.48 mm.
^Three/ Mm^TwoEven above, it is not necessarily suitable for occupant head protection
Sufficient shock absorption properties cannot be obtained, replacing V / A
It turned out that an indicator was needed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shock absorbing structure for absorbing a shock with a plurality of ribs having a height of 35 mm or less, the shock absorbing structure exhibiting shock absorbing characteristics suitable for protecting the head of an occupant. An object of the present invention is to provide an idea for efficiently designing a rib structure while providing an application.

[0007]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies on the above-mentioned problems, the impact was 35
a shock absorbing structure that absorbs with a plurality of ribs of not more than 1 mm, wherein the rib strength index P is in a specific range and that the use thereof achieves the object of the present invention,
The present invention has been completed.

That is, according to the present invention, the impact is 35 m in height.
m is a shock-absorbing structure that absorbs with a plurality of ribs of m or less, and a rib strength index P defined by the following equation is 10 to 35 m
m ² is a shock absorbing structure. P = N × t × S N: value obtained by dividing the number of rib intersections existing in the effective area Q by the total length of the ribs existing in the effective area Q (1 / mm) t: rib existing in the effective area Q S: Average value (m) of the total cross-sectional area of the ribs existing in the effective range Q
m ² ) Q: Inside a circle of radius R (mm) centered on the impact point R: Defined by the following formula R = 0.85 × h + 40.1 h: Rib height (mm) An automobile interior part comprising the above-mentioned shock absorbing structure. Hereinafter, the present invention will be described in detail.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A shock absorbing structure according to the present invention is a shock absorbing structure which absorbs a shock with a plurality of ribs having a height in a shock direction of 35 mm or less, and a rib strength index defined by the above equation. P is 10 to 35 mm ² , preferably 15 to
It is a shock absorbing structure characterized by being 30 mm ² .

In the above equation, Q means the inside of a circle having a radius R centered on the point of impact. Here, the impact point is a point where the impact absorbing structure first comes into contact with the object when the impact absorbing structure receives an impact from the object. The radius R is R = 0.85 × h + 40.1, where h is the height of the rib.
Shall be given by N, t, and S are values defined for a rib existing in the effective range Q.
First, N is a value obtained by dividing the number of rib intersections existing in the effective range Q by the total length of the ribs existing in the effective range Q. Further details will be described using the shock absorbing structure shown in FIGS. 1 and 2. FIG. 1 is a drawing showing an example of the shock absorbing structure of the present invention, and FIG. 2 is a plan view of FIG. In FIG. 2, reference numeral 19 denotes an effective range Q, that is, the inside of a circle 20 having a radius R, and a rib intersection existing in the effective range Q of 19 is defined by intersections 11 to 14 of the rib intersections 11 to 18. There are four. Further, the effective range Q of 19, the rib length L ₁ of the portion 2 places, rib length L ₂ portions one place, there portion of the rib length L ₃ is one place, in a valid range by Q The total length of the rib is 2 × L ₁ + L ₂ + L ₃
Given by Next, t is the average thickness of the rib existing in the effective range Q. Here, when there is a distribution in the thickness of the rib existing in the effective range Q, the average thickness is an average value obtained in consideration of the distribution. Next, S is the average value of the total cross-sectional area of the ribs existing in the effective area Q, and is a value obtained by multiplying the average thickness t by the total length of the ribs existing in the effective area Q. It is.

When the occupant's head collides with the shock absorbing structure having the rib strength index P of 10 to 35 mm ² , the occupant's head is not subjected to a large impact load, and the occupant's head is protected. . That is, the shock absorbing structure exhibits shock absorbing characteristics suitable for protecting the head of the occupant. If the value of P is larger than 35 mm ² , the ribs are too strong, so that the occupant's head receives a greater load than the ribs, and it is not possible to obtain shock absorption characteristics suitable for protecting the head. On the other hand, when the value of P is less than 10 mm ² , the ribs are too weak, so that the impacts cannot be completely absorbed only by the ribs. The part receives a large load from a metal part of the vehicle body such as a pillar, and it is not possible to obtain a shock absorbing characteristic suitable for protecting the occupant's head.

In the shock absorbing structure of the present invention, the plurality of ribs may be arranged regularly. When the ribs are regularly arranged, it is possible to obtain a structure having stable shock absorption characteristics.

As the material of the rib, a thermoplastic resin is used.
By using a thermoplastic resin, an inexpensive and stable shock absorbing structure having shock absorbing characteristics can be obtained.

Examples of the thermoplastic resin include polyethylene, polypropylene, polyvinyl chloride, nylon,
Polycarbonate, polyethylene terephthalate, PM
Various thermoplastic resins such as MA and ABS resins, modified products thereof, polymer alloys, and mixtures thereof may be mentioned. The above thermoplastic resins may be used alone or in combination of two or more. Among these, olefin-based resins such as ethylene homopolymer, propylene homopolymer, and copolymers with other copolymer components such as α-olefins are preferable, and propylene-based resins are more preferable. Propylene resin is a propylene homopolymer, propylene as a main component, ethylene, α-carbon having 4 or more carbon atoms.
It is a random copolymer with an olefin or other monomer, or a block copolymer containing propylene as a main component and ethylene, an α-olefin having 4 or more carbon atoms or another monomer. Various kinds of commonly used additives such as fillers such as talc, mica, and glass fiber, antioxidants, ultraviolet absorbers, flame retardants, and colorants are added to such thermoplastic resins or thermoplastic resin compositions. An agent may be contained as needed.

The shock absorbing structure of the present invention can be manufactured by a known molding method, for example, an injection molding method, an injection compression molding method or the like.

[0016]

Hereinafter, the present invention will be described based on examples.
The present invention is not limited to these examples. The evaluation methods in Examples and Comparative Examples were as follows. (1) Impact test Occupant head protection regulation FMVSS201 (Federal Motor Ve) stipulated by US automobile safety standards
Hicle Standard No. An impact test was carried out by a method according to 201). Impact tester (manufactured:
The head of a dummy doll (FMH: manufactured by Vector Corporation) is allowed to fly freely at a speed of 24 km / h with air pressure using Hodogaya Giken Co., Ltd., model: HG-12132), and the shock absorbing structure is made of the same material as the shock absorbing structure The impact-absorbing structure was hit from above on a flat plate having a thickness of 2 mm larger than the body. Then, the combined acceleration calculated from the three-axis acceleration sensor values in the dummy doll head is obtained, and the head injury value, HIC, is calculated from the calculated acceleration.
(D) The value was calculated.

Example 1 The shock absorbing structure of Example 1 was formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice was arranged in a 2 × 3 array. Grid spacing 35mm, rib height 25
mm. Also, the rib thickness is slightly tapered,
The thickness was gradually changed at a constant rate according to the height of the rib, with 1.12 mm at the tip and 1.56 mm at the root.
This is basically a restriction resulting from a manufacturing method of injecting a molten thermoplastic resin into a mold and removing the mold after molding. And N is 0.0138 (1 / mm), t
Was 1.34 (mm) and S was 776 (mm ² ).
This shock absorbing structure is a propylene-ethylene block copolymer (Sumitomo Noblen WP71 manufactured by Sumitomo Chemical Co., Ltd.).
2F, melt index (MI) = 14 g / 10 minutes)
Was cut out from the injection-molded shape using the pellets described above to obtain the above structure. Table 1 shows the evaluation results.

Embodiment 2 The shock absorbing structure of Embodiment 2 is formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice is arranged in a 3 × 2 array. Grid spacing is 30mm, rib height is 20
mm. The rib thickness is 0.95mm at the tip,
It was 1.30 mm at the root. N is 0.0235 (1
/ Mm), t is 1.13 (mm), S is 576 (m
m ² ). The material and molding method of the shock absorbing structure were the same as in Example 1. Table 1 shows the evaluation results.

Example 3 The shock absorbing structure of Example 3 was formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice was arranged in a 5 × 3 array. Grid spacing 20 mm, rib height 25
mm. The rib thickness is 0.69mm at the tip,
It was 1.12 mm at the root. N is 0.0289 (1
/ Mm), t is 0.91 (mm), S is 692 (m
m ² ). The material and molding method of the shock absorbing structure were the same as in Example 1. Table 1 shows the evaluation results.

Example 4 The shock absorbing structure of Example 4 was formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice was arranged in a 1 × 3 array. Grid spacing is 30mm, rib height is 25
mm. The rib thickness is 1.56mm at the tip,
It was 2.00 mm at the root. N is 0.0267 (1
/ Mm), t is 1.78 (mm), S is 534 (m
m ² ). The material and molding method of the shock absorbing structure were the same as in Example 1. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 1 The shock absorbing structure of Comparative Example 1 was formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice was arranged in a 2 × 2 array. Grid spacing 20 mm, rib height 25
mm. The rib thickness is 0.69mm at the tip,
It was 1.12 mm at the root. N is 0.0375 (1
/ Mm), t is 0.91 (mm), S is 218 (m
m ² ). The material and molding method of the shock absorbing structure were the same as in Example 1. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 2 The shock absorbing structure of Comparative Example 2 was formed by forming a plurality of ribs having a constant thickness in a regular lattice, and the lattice was arranged in a 3 × 2 array. Grid spacing is 30mm, rib height is 25
mm. The rib thickness is 1.56mm at the tip,
It was 2.00 mm at the root. N is 0.0235 (1
/ Mm), t is 1.78 (mm), S is 908 (m
m ² ). The material and molding method of the shock absorbing structure were the same as in Example 1. Table 1 shows the evaluation results.

[0023]

[Table 1]

[0024]

As described in detail above, according to the present invention,
By setting the rib strength index P to 10 to 35 mm ² ,
It is possible to provide a shock absorbing structure that exhibits shock absorbing characteristics suitable for protecting the head of an occupant when used in an automobile interior part. Further, the present invention can provide a concept for efficiently designing an automobile interior part using a rib. Further, the shock absorbing structure of the present invention is suitable for automobile interior parts, particularly for pillar garnishes.

[Brief description of the drawings]

FIG. 1 is a drawing showing an example of a shock absorbing structure of the present invention.

FIG. 2 is a drawing showing a plan view of FIG. 1;

[Explanation of symbols]

L ₁ , L ₂ , L ₃ ... Rib lengths 11, 12, 13, 14, 15, 16, 17, 18,.
・ Rib intersection point 19 ・ ・ ・ Effective range Q 20 ・ ・ ・ A circle of radius R which defines the effective range

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62D 25/06 B62D 25/06 A F16F 7/12 F16F 7/12 F term (Reference) 3D003 AA05 BB01 CA33 CA34 DA21 3D023 BA01 BA07 BB06 BB10 BB14 BB22 BC01 BD08 BD10 BE03 BE04 BE09 BE31 3J066 AA23 BA04 BB01 BC03 BD05 BF01 BG01

Claims (7)

[Claims] An impact absorbing structure for absorbing an impact with a plurality of ribs having a height of 35 mm or less, wherein a rib strength index P defined by the following equation is 10 to 35 mm ^2. Absorbing structure. P = N × t × S N: value obtained by dividing the number of rib intersections existing in the effective area Q by the total length of the ribs existing in the effective area Q (1 / mm) t: rib existing in the effective area Q S: Average value (m) of the total cross-sectional area of the ribs existing in the effective range Q
m ² ) Q: Inside the circle of radius R (mm) centered on the impact point R: Defined by the following equation R = 0.85 × h + 40.1 h: Rib height (mm) 2. The shock absorbing structure according to claim 1, wherein the rib strength index P is 15 to 30 mm ² . 3. The shock absorbing structure according to claim 1, wherein the plurality of ribs are regularly arranged. 4. The shock absorbing structure according to claim 1, wherein the material of the plurality of ribs is a thermoplastic resin. 5. The shock absorbing structure according to claim 4, wherein the thermoplastic resin is a propylene resin. 6. An automobile interior part comprising the shock absorbing structure according to any one of claims 1 to 5. 7. The automobile interior part according to claim 6, wherein the automobile interior part is a pillar garnish.