Land vehicles – Wheeled – Attachment
Reexamination Certificate
2003-05-05
2004-10-26
Ellis, Christopher P. (Department: 3618)
Land vehicles
Wheeled
Attachment
C428S158000, C428S160000
Reexamination Certificate
active
06808206
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an impact absorbing member and, particularly to an impact absorbing member which is suitably adapted to absorb impact energy exerted on the head of an occupant in a vehicle cabin to reduce the head injury criteria value in the event of a vehicle collision.
The followings are impact absorbing members for use in vehicles which have been conventionally proposed.
(1) An impact absorbing member comprises a resin pillar garnish having a hollow shape wherein a hollow is filled with rigid polyurethane foam for absorbing impact energy (Japanese Patent H06-42437A).
(2) A pad member is made of foamed material or rubber material (a prior art description of Japanese Patent H08-2358A).
(3) A cushion body is made of rigid polyurethane foam and is covered by a shape keeping member of sheet metal having a recess formed therein (Japanese Patent H08-72642A).
(4) An impact absorbing member is provided by using a garnish (trim) (Japanese Patent H06-211088A).
(5) An impact absorbing member is made of resin beads and has a number of ribs formed on one surface (Japanese Patent H07-16867A).
(6) An impact absorbing member is constituted of a polyolefin resin material which has ribs arranged in a lattice shape (Japanese Patent H08-142234A, Japanese Patent H08-295194A).
The aforementioned conventional impact absorbing members have the following drawbacks, respectively.
The impact absorbing member disclosed in Japanese utility model H06-42437A uses the rigid polyurethane foam as the head protective material. However, it has a structure complex with the hollow resin piece (garnish). Therefore, the rigid polyurethane foam is required to have low compressive strength of 0.02 to 0.2 MPa. This means that this does not take advantage of characteristics of the rigid polyurethane foam. The purpose of its concave and convex shape is just to reduce the weight and to keep the strength, and not to improve the energy absorbing capacity. Therefore, this does not have improved energy absorbing capacity.
The impact absorbing member disclosed as a prior art of Japanese Patent H08-2358A is an example of a pad member for absorbing impact made of foamed material or rubber material. In this example, the pad member is elastically deformed and thus does not suggest the usage of rigid polyurethane foam. Portions of a corrugated section attached to a vehicle body are extremely thin. To obtain sufficient energy absorbing capacity, the thickness of the pad member should be large. Accordingly, the cabin space of the vehicle is reduced, thus worsening the comfort, the facility of riding, and further the visibility.
The impact absorbing structure disclosed in Japanese Patent H08-72642A has a concave shape as a whole, but a soft or rigid polyurethane form itself used as crushing material does not have a recess for improving the energy absorbing capacity. The purpose of a recess formed in the impact absorbing structure is just installation, not improvement of the energy absorbing capacity. In this publication, it is stated that it can not exhibit sufficient energy absorbing efficiency if the entire rigidity is too high or too low. However, there is no description about specific value and range. It is hard to say that this impact absorbing structure securely exhibits excellent energy absorbing efficiency.
The impact absorbing member disclosed in Japanese Patent H06-211088A has a structure to be fixed together with a garnish to a vehicle body by fasteners so that the garnish is necessary for installation of this impact absorbing member. For utilizing the impact absorbing member as a head protective member, the location adaptability is limited, for example, it is not suitably adapted to a side rail. The impact absorbing member does not have a concavity or convexity. Though it is stated that the impact absorbing member has such a thickness as to absorb impact energy, there is no description about specific thickness and hardness. It is also hard to say that the impact absorbing member securely exhibits excellent energy absorbing efficiency.
The impact absorbing member disclosed in Japanese Patent H07-16867A is made of resin beads. When a force is locally exerted on a surface of the impact absorbing member by a spherical body such as a head dummy, the force focuses on beam portions between the ribs, thus not obtaining sufficient impact absorbing capacity. If the impact absorbing member having the aforementioned configuration is made of rigid polyurethane foam, the beam portions may be broken, thus not obtaining sufficient stroke for absorbing impact energy.
According to the impact absorbing member disclosed in Japanese Patent H08-142234A and Japanese Patent H08-295194A, the thickness of the lattice-shaped ribs is small such as 0.6 to 1.2 mm. In addition, since the ribs made of polyolefin resin material absorbs energy generally by the bending of the ribs, the impact absorbing member has a drawback that the capacity has high dependence of the direction of impact.
As mentioned above, any one of the aforementioned conventional impact absorbing members is not the one whose configuration is positively devised to obtain the optimal energy absorbing capacity. Accordingly, high energy absorbing capacity can not be imparted to these impact absorbing members.
On the other hand, at pillars and side rails in an automobile, the dimension in thickness has a greater effect on the comfort in the cabin and the visibility for the safety. To reduce the head injury criteria value to protect the occupant without impairing these factors, an impact absorbing member is required which is thin, but can exhibit sufficient energy absorbing efficiency.
As an impact absorbing member for use in vehicles which can solve the aforementioned problems and which has excellent energy absorbing capacity and is suitably adapted to absorb impact energy exerted on the head of an occupant in a vehicle cabin to reduce the head injury criteria value in the event of a vehicle collision, an impact absorbing member has been previously proposed by the applicant of this application, which has a plate-like configuration and is made of rigid polyurethane foam having compressive strength of a predetermined value or more, and which has recesses formed in at least one surface thereof (Japanese Patent 2000-6741A) published on Jan. 11, 2000, a corresponding European application of which is EP 967124 A2 published on Dec. 29, 1999.
In this impact absorbing member, walls between adjacent recesses of the impact absorbing member made of rigid polyurethane foam are broken to absorb impact energy. The broken walls sequentially enter the recesses, thereby obtaining stable energy absorbing capacity. The entrance of the walls into the recesses provides the stroke for absorbing energy, thereby sufficiently reducing the head injury criteria value suffered by an occupant.
In this impact absorbing member, it is preferred that the ratio of the volume of the recesses to the sum of the volume of solid portions made of the rigid polyurethane foam and the volume of the recesses (hereinafter, sometimes referred to as “recess volume ratio”) is 10 to 40%.
Therefore, the object of the present invention is to provide an impact absorbing member for use in vehicles which is an improvement over the impact absorbing member of Japanese Patent 2000-6741A and which has excellent energy absorbing capacity and is suitably adapted to absorb impact energy exerted on the head of an occupant in a vehicle cabin to reduce the head injury criteria value in the event of a vehicle collision.
SUMMARY OF THE INVENTION
An impact absorbing member of the present invention is made of rigid polyurethane foam and has a plate-like shape, and includes recesses formed in at least one surface thereof to be arranged in parallel along one direction, wherein each recess is formed in such a shape as to have sectional area decreasing toward the deepest point.
It is preferable that the shape of each recess is acute at the bottom in the depth direction of the impact absorbing m
Kaneda Hiroshi
Yata Tatsuo
Bottorff Christopher
Bridgestone Corporation
Ellis Christopher P.
Manabu Kanesaka
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