JP4021929B2 - Shock-absorbing automotive floor spacer - Google Patents

Description

  The present invention relates to a shock-absorbing automobile floor spacer that is laid around a passenger's foot of an automobile. More particularly, the present invention relates to a shock-absorbing automobile floor spacer for securing flatness of a floor surface, reducing stepping-down, and protecting passengers against impact generated inside and outside the vehicle.

In recent years, an increasing number of cases in which hard foamed plastic floor spacers such as polystyrene foam are adopted as members that can improve the comfort of automobiles and share a common platform. This is because these rigid foam plastics are extremely light in weight per unit volume, can be molded with a mold, have excellent shapeability, and have a low cost per unit volume. By having.
On the other hand, as a shock absorber for shocks generated inside and outside the automobile, for example, an energy absorbing material placed inside the door, foamed urethane is used that has a low rise in stress even when the amount of distortion caused by impact increases. Has been. In addition, for the purpose of further improving the collision safety of automobiles, it is required to improve the vehicle body structure and to add shock absorbing performance to a member that applies a load to the occupant during a collision.

  However, with respect to floor spacers, the technology for improving habitability and safety has not been completed, and the following problems remain. That is, in the foamed polystyrene molded product, the sag with respect to the stepping load is large, and the stress rise with respect to the impact compression is also large. In addition, foamed urethane has problems such that urethane cannot be recycled because it is a thermosetting plastic, and that characteristic changes occur due to high water absorption.

  The present invention has been considered in view of the above circumstances, and it is an object of the present invention to provide an impact-absorbing automobile floor spacer that is not only capable of improving habitability and impact safety with a lighter member but also suitable for recycling. .

In order to achieve the above object, the present invention provides a floor spacer, which is made of a hard foam and is laid on the floor surface of an automobile, formed of a flat portion and an inclined portion protruding in front of the flat portion, and the floor. A thick portion is formed on the interior side of the vehicle interior of the spacer, and a honeycomb structure, a slit structure and / or a protrusion structure is formed on the floor surface side, and the height of the honeycomb structure, the slit structure and / or the protrusion structure is increased. The thickness of the floor spacer body is 50% or more, and the contact area with the floor surface of the portion where the honeycomb structure, slit structure and / or protrusion structure is formed is 10% or more and 60% or less. is there.

In the present invention, it is preferable that the width of the ribs or protrusions of the honeycomb and the slit is 20% or less with respect to the thickness of the floor spacer .

Further, in the present invention, the hard foam is first foamed with foaming thermoplastic resin particles to a predetermined density, then filled into a mold and molded by heating with steam or the like, and the density is 30 kg / m ³ or more and 200 kg. / M ³ or less is preferable.

  The shock-absorbing automobile floor spacer according to the present invention is a lighter member and not only can improve habitability and impact safety, but is also suitable for recycling.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 shows an embodiment of a shock-absorbing automobile floor spacer according to the present invention. This shock-absorbing automobile floor spacer has a flat portion 1 where the floor spacer is located on the floor surface of the automobile and an inclined portion 2 located on the inclined floor surface in front of the automobile floor surface. Is configured to protrude in a state inclined obliquely upward and forward of the flat portion 1.
Further, the flat portion 1 and the inclined portion 2 of the floor spacer have thick portions 11 and 21 on the side located on the indoor side of the automobile, respectively, and have a honeycomb structure on the side opposite to the automobile floor and the inclined floor. The shock absorbers 12 and 22 each having a slit structure and / or a protrusion structure are provided.

FIG. 2 shows the honeycomb structure in the shock absorbing portions 12 and 21, FIG. 3 shows the slit structure, and FIG. 4 shows the protrusion structure, and these honeycomb structures, slit structures, and protrusion structures can be used alone or in combination. Fulfills the function.
The width of the ribs or protrusions of the honeycomb and slit with respect to the thickness of the flat portion 1 and the inclined portion 2 is preferably 20% or less. When an impact is applied, for example, as shown in FIG. 5, the impact absorbing portions 12 and 21 are deformed. At this time, if the width of the honeycomb, slit, or protrusion is 20% or less, the compressive stress is lowered and the impact is applied. It is easy to be deformed and can exhibit sufficient shock absorbing performance.

Moreover, in this embodiment, it is preferable that the thickness of the thick portions 11 and 21 located on the indoor side is 50% or less with respect to the thickness of the flat portion 1 and the inclined portion 2 of the floor spacer. When an impact is applied to the flat portion 1 and the inclined portion 2, the shock absorbing portions 12 and 22 are deformed as shown in FIG. , 21 has a thickness of 50% or less, the deformed portion is thick and the shock absorbing performance is enhanced.
In addition, by changing the shape of the ribs or protrusions of the honeycombs and slits in the flat portion 1 and the inclined portion 2 continuously or stepwise in the thickness direction of the floor spacer, the compressive stress is physically changed. High impact absorption performance can also be exhibited.

  The rigid foam used in the present embodiment is a rigid foamed plastic, for example, a non-crosslinkable thermoplastic resin that can be recycled. After the foaming resin particles are first foamed to a predetermined density, the mold is filled. A foamed molded product formed by heating such as steam is preferred. Examples of such hard foamed plastics include foamed polyolefins such as foamed polyethylene and foamed polypropylene, and foamed polystyrene-based plastics are preferred from the viewpoint of economy and excellent molded article physical properties. Examples of the expanded polystyrene plastic include foams such as styrene / acrylonitrile resin with improved chemical resistance and styrene / acrylonitrile / α-methylstyrene resin with improved heat resistance.

The table in FIG. 6 shows the relationship between compression stress and compression strain in a static compression test of a styrene / acrylonitrile resin foam (Hitachi Chemical Industries, Ltd., High Beads GR), which is an example of a hard foam plastic. From this table, it can be seen that when the compression strain is 10%, the density at which the compression pressure is 0.3 MPa or more is 33 kg / m ³ or more.
The required strength and density differ depending on the assumed pressure load and the structure of the floor spacer, but the density based on the rigid foam plastic material is 30 kg / kg from the viewpoint of both shock absorption performance and stepping resistance and lightweight. m ³ or more and 200 kg / m ³ or less are preferable.

If the required compressive strength value and the density of the hard foam plastic are determined, the hard foam plastic as shown in FIG. It can be determined by a simple calculation from the value of the compressive stress obtained from the figure showing the relationship between the compressive stress and the compressive strain. For example, the required 10% compressive strength is 0.15 MPa, and the density of the hard foam plastic is 33 kg / m ³ . In this case, since the value of 10% compressive strength at a density of 33 kg / m ³ is 0.30 MPa from FIG. 6, the required contact area is 0.15 / 0.30 × 100 = 50%.
The contact area of the shock-absorbing automobile floor spacer in this embodiment is thus determined.

  The area of contact of the shock absorbers 12 and 22 with the floor surface when actually laid is the portion where the honeycomb structure, the slit structure and / or the protrusion structure are formed in order to achieve both shock absorption performance and light weight. It is made to be 10% or more and 60% or less. If the contact area is less than 10%, the required density of rigid foamed plastic is high, and even if the impact absorbing performance is satisfactory, the light weight may not be satisfied. If the contact area exceeds 60%, the light weight may be satisfactory. The compressive strength is low, and the desired shock absorbing performance may not be exhibited.

Here, the density of the hard foamed plastic is obtained by obtaining the load applied to the flat portion 1 and the inclined portion 2 of the floor spacer, and the density indicating the compressive strength that can withstand this, for example, compressive stress and compressive strain as shown in FIG. It is easily determined by obtaining from a diagram showing the relationship. For example, when a load of 30 kg is applied to the heel (area 5 × 3 = 15 cm ² ) of shoes placed on the flat portion 1 and the inclined portion 2, the compressive strength required for the floor spacer is 30/15 = 2 kg / cm ^2. ≈0.2 MPa.
Since the shock absorbing parts 12 and 22 of the flat part 1 and the inclined part 2 have a honeycomb structure, a slit structure or a protruding structure, the necessary compressive strength is divided by the ratio of the contact area to the floor surface and the inclined floor surface. Become. For example, when the contact area is 60% and the load is 0.2 MPa as described above, the strength required for the flat portion 1 and the inclined portion 2 is 0.2 MPa / 0.6 = 0.33 MPa.

  When the shock-absorbing automobile floor spacer of the present embodiment is intended to protect the occupant from the impact applied from the bottom and the front, the appearance is as shown in FIG. 1 and FIG. When it aims at protecting a passenger | crew from the impact added from a bottom part, a front part, and a side part, as shown in FIG.7 (b), it becomes the shape where the foamed plastic protruded from the side surface. There are no particular restrictions on the shape of the honeycomb, slits and protrusions in the impact absorbing portion. The normal honeycomb structure means a regular hexagonal honeycomb shape, but in the present embodiment, n may be an n-gonal shape, a circular shape, or an elliptical shape having 3 or more.

  The shock-absorbing automotive floor spacer of this embodiment works synergistically with the cushioning properties of the hard foamed plastic itself and the structure of the honeycomb or the like, and exhibits high shock-absorbing performance.

Examples will be described below in more detail, but the present invention is not limited thereto.
The table of FIG. 8 shows the relationship between dynamic compressive strain and compressive stress of an example made of hard foamed plastic and having a honeycomb structure and a comparative example made of the same hard foamed plastic as in this example and not having a honeycomb structure. Indicates. In the case of the comparative example, as the dynamic compressive strain increases, the compressive stress gradually increases and the shock absorption performance decreases, whereas in the case of the example, the strain region indicating 0.6 MPa is 15% to 60%. It can be seen that they are almost constant, have high shock absorption performance, and can reduce damage to passengers.

(Example specifications)
A shock-absorbing automotive floor spacer having the appearance shown in FIG. 1 is made of a hard foamed plastic with a density of 67 kg / m ³ made of “Hitachi Chemical Industry Co., Ltd., expandable styrene / acrylonitrile resin, high beads GR”. did. The impact absorbing portion has a honeycomb structure shown in FIG. The thickness of the flat portion and the inclined portion is 50 mm, the thickness of the thick portion is 10 mm, the honeycomb height is 40 mm, and the honeycomb rib width is 5 mm. The contact area of the honeycomb ribs with respect to the laid floor area is 36%. That is, the rib width of the honeycomb is 10%, the thickness of the thick portion is 20%, and the porosity of the honeycomb structure is 51.2% with respect to the thickness (50 mm) of the flat portion and the inclined portion.

(Characteristics of Examples)
In order to clarify the effects of the examples, the floor foam for automobiles having the same foamed plastic and the same weight as the examples and the density of 33 kg / m ³ were compared with the stepping resistance and the shock absorbing performance.
(Deep-proof)
When a stainless steel round bar having a diameter of 12 mm was applied with a weight of 30 kg and compressed 10 times every 10 seconds, the strain in the example was 1% or less, whereas the comparative example sank 8%. The results are shown in FIG.
(Shock absorption performance)
In accordance with JIS-Z0235, a 4.5 kg weight with a bottom area of 70 cm ² was dropped from a height of 2.5 m on the molded product, and the impact value at that time was measured. Compared to 90G, the comparative example was 180G.

The figure which shows the whole the floor spacer for shock-absorbing automobiles concerning embodiment of this invention. The figure which shows the example of a honeycomb structure. The figure which shows the example of a slit structure. The figure which shows the example of protrusion structure. The figure which shows the modification of the honeycomb structure after an impact test. The figure which shows the relationship between the compressive strain and the compressive stress of Hitachi Chemical Co., Ltd. "high bead GR" molded article. (A) is a figure which shows the example of the floor spacer for shock absorption motor vehicles aiming at passenger | crew protection with respect to the impact from a bottom part and a front part. (B) is a figure which shows the example of the floor spacer for shock absorption motor vehicles aiming at passenger | crew protection with respect to the impact from a floor part, a front part, and a side part. The figure which shows the impact-absorption characteristic measurement result of an Example and a comparative example. The figure which shows the depression test result of an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flat part 2 Inclined part 11,21 Thick part 21,22 Shock absorption part A Indoor side B Floor side

Claims (3)

A floor spacer made of a hard foam and laid on the floor of an automobile is formed with a flat part and an inclined part protruding to the front of the flat part,
And while forming a thick part on the indoor side of the automobile of the floor spacer, forming a honeycomb structure, a slit structure and / or a protrusion structure on the floor surface side,
The height of the honeycomb structure, slit structure and / or protrusion structure is 50% or more of the thickness of the floor spacer body, and the floor surface of the portion where the honeycomb structure, slit structure and / or protrusion structure is formed An impact-absorbing automotive floor spacer, characterized in that the contact area with the substrate is 10% or more and 60% or less . 2. The shock-absorbing automobile floor spacer according to claim 1, wherein a width of the rib or protrusion structure of the honeycomb structure and slit structure is 20% or less with respect to a thickness of the floor spacer. The hard foam is first foamed with a predetermined density of expandable thermoplastic resin particles, then filled into a mold and molded by heating with steam or the like, and the foam has a density of 30 kg / m ³ or more and 200 kg / m ³ or less. The impact-absorbing automobile floor spacer according to claim 1 or 2, wherein the floor spacer is a molded article.

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