Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-07-20
2001-04-24
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C248S560000, C248S615000, C248S634000, C293S102000, C293S120000, C293S132000, C428S423100, C521S050000, C521S174000
Reexamination Certificate
active
06221930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shock absorber, and more particularly relates to a shock absorber which is ideal as a shock absorbing pad incorporated in a door trim, center pillar trim, and the like, incorporated inside a vehicle, for absorbing a shock received by a passenger when the vehicle suffers a collision.
2. Description of the Related Art
To absorb a shock which a passenger receives in the upper torso during a vehicular collision, a shock absorbing material must exhibit stress which is linear with respect to the compression stroke (compressive distortion). That is, the material should have an F-S waveform (force-stroke waveform) wherein the stress is proportional to the compression stroke. Conventionally, an iron plate, semi-rigid polyurethane foam, and the like have been used in many cases as materials having this sort of a linear F-S waveform.
However, although an iron plate, one of the conventionally used shock absorbing materials, has a linear F-S waveform as shown in
FIG. 2A
, it has a drawback in that it is heavy and consequently increases the weight of the vehicle.
On the other hand, semi-rigid polyurethane foam has the F-S waveform shown in
FIG. 2B
, which has a drawback in that the F-S waveform is linear only during the initial period of compression (when the compression stroke is small), and deviates from the required waveform when the compression stroke increases.
Rigid polyurethane foam is generally used as a buffer material, but even a rigid polyurethane foam with a low level of hardness, having a compressive stress of approximately 3.0 kg/cm
2
, or a rigid polyurethane foam with a high level of hardness, having a compressive stress of approximately 8.0 kg/cm
2
, has a waveform which deviates considerably from the required waveform, as shown schematically by the F-S waveform of FIG.
2
C.
As shown in
FIG. 8
(vertical cross-sectional view), shock energy absorbers
82
, for protecting the chest to shoulder part of the passenger in a vehicular collision, are provided at necessary positions on the rear face of a door trim
81
of a vehicle (the face on the opposite side to the inside of the vehicle). The energy absorbers
82
usually consist of a material with excellent energy-absorbing characteristics such as rigid polyurethane foam, or bead-like foam bodies of polypropylene, polyethylene, or a polyolefine-type resin, and are securely attached to the door trim
81
using hot-melting adhesive or double-sided tape or the like.
Each of the above materials of the energy absorbers has a comparatively high level of hardness, and therefore the energy absorbers
82
have low shock-durability and tend to break during a collision. Consequently, when the conventional energy absorbers
82
are used, as for instance in the case shown in
FIG. 8
, where an MDB (Moving Deformable Barrier)
85
has collided sideways from the outer plate
83
side, the shape of the outer plate
83
becomes distorted and the MDB
85
enters the inside of the vehicle, and as a result, the energy absorbers
82
are broken by the shock and are shattered. Then, after the energy absorbers
82
have been lost, the crash dummy
84
collides with the door trim
81
, and as a result, no energy-absorbing effect is obtained from the energy absorbers
82
.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the problems described above in the art by providing a shock absorber comprising a light foam resin material having an ideal F-S waveform required for a shock absorbing pad.
In a first aspect, a shock absorber consists of foam resin material, and its cross-sectional area in a direction perpendicular to a compression axis direction changes at least partially in the compression axis direction.
In a second aspect, a shock absorber consists of foam resin material, and its cross-sectional area in a direction perpendicular to a compression axis direction increases at least partially in the compression axis direction.
By changing the cross-sectional area of the shock absorber, a relation between distortion and compressive stress in the compression axis direction is made approximately linear.
Even in the case of a pad consisting of a foam resin material which does not have a linear F-S waveform, by at least partially changing and/or increasing the cross-sectional area thereof in the compression axis direction, the relation between distortion and compressive stress in the compression axis direction, that is the F-S waveform, can be made approximately linear.
The shock absorber of the present invention may consist of a rigid polyurethane foam which has an F-S waveform such as that shown in FIG.
2
C, and can easily be used as a shock absorbing pad having an ideal F-S waveform by providing a taper, a dip, a notch, a step, or the like therein.
The shock absorber of the present invention is particularly useful inside a vehicle as a shock absorbing pad for protecting a passenger of the vehicle, by absorbing a shock received by the passenger when the vehicle suffers a collision, and especially as a shock absorbing pad incorporated in a door trim and center pillar trim and the like of the vehicle, to protect the passenger from his chest to his shoulders.
In the present invention, the F-S waveform (that is, the relation between compressive distortion (stroke) and the compressive stress in the compression axis direction) of the material itself is determined, as shown in
FIG. 3
, by placing a test material
11
having a thickness of 50 mm×50 mm×50 mm between pressure jigs
12
and
13
, compressing it at a compression speed of 50 mm/min, and measuring its compressive stress against the compression stroke.
The F-S waveforms of shock absorbing pads
1
A to
1
I, as shown later in
FIG. 1A
to
FIG. 1I
, can be similarly determined by replacing the test material of
FIG. 3
with the shock absorbing pads
1
A to
1
I, and inserting them between the pressure jigs
12
and
13
as above.
It is another object of the present invention to provide a shock energy absorber which does not shatter after breakage due to shock, can adequately achieve a desired energy absorbing ability, and has superior effects in protecting passengers.
In a third aspect, a shock energy absorber has an energy-absorbing material and a reinforcing material attached thereto.
Since the energy absorber of the third aspect has the reinforcing material attached to an energy-absorbing material, even when the energy-absorbing material breaks due to a shock, the reinforcing material prevents it from shattering, thereby reliably holding the energy-absorbing material in its designed position. Consequently, it can adequately achieve a desired energy-absorbing ability, and reliably protect passengers.
The reinforcing material may comprise worsted felt, cheesecloth, tufnel, a metal sheet, or a resin sheet. Such a reinforcing material should preferably be glued to a surface of the energy-absorbing material by an adhesive, or alternatively, attached in a single body to a surface of the energy-absorbing material by joint blowing during manufacture of the energy-absorbing material.
The energy absorber of the third aspect is particularly appropriate for use inside a vehicle, and especially as an energy absorber for side projection incorporated in a door trim of the vehicle, to protect a passenger from his chest to his shoulders.
REFERENCES:
patent: 4668555 (1987-05-01), Uekado et al.
patent: 5575871 (1996-11-01), Ryoshi et al.
patent: 6057378 (2000-05-01), Perstnev et al.
Nabeshima Yoichi
Tabata Keiichiro
Tada Shin
Yata Tatsuo
Bridgestone Corporation
Cooney Jr. John M.
Kanesaka & Takeuchi
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