Note: Descriptions are shown in the official language in which they were submitted.
CA 02173721 1996-04-17
1
SPECIFICATION
RESIN-MADE SHOCI(~ ABSORBING MEMBER FOR A VEHICLE
AND
METHOD FOR PRODUCING THE SAME.
Technical Field
This invention relates to a resin-made shock absorbing member for a vehicle
and a
method for producing the same.
Background Art
Conventionally, a shock absorbing member for a vehicle, such as a bumper and a
bumper beam, is made of metal. The metal bumper and the like have sufficient
strength, but,
several disadvantages, for example, heavy weight and easy corrosion.
Consequently, in
recent years, the bumper and the like which are made of plastics have been
used in order to
save resources and reduce weight.
The aforementioned plastic bumper and the like are usually produced by means
of
injection molding. But, by using injection molding in the production process,
there are
disadvantages in that a large molding apparatus is required in order to
produce the bumper
and the like that have relatively large moldings, and in that the molding
apparatus is costly
in view of the necessity of high pressure for the injection molding.
Furthermore, by using
injection molding in the production process, an outer configuration of the
molding can be
relatively freely designed by changing the cavity configuration in a die, but,
it is difficult to
produce the bumper and the like which have a hollow structure capable of
effectively
absorbing shock.
Consequently, for effective shock absorbing, it is proposed to use the shock
absorbing member for a vehicle which has the hollow structure produced by
means of blow
molding.
Fig. 16 shows a bumper beam 90 as a conventional example of the shock
absorbing
member for a vehicle which has the hollow structure produced by means of blow
molding.
The bumper beam 90 is composed of a curved portion 91 having the hollow
structure and attachment portions 92 for fixing to a vehicle body and to be
formed in such a
way that it is united and thus continuously formed with the curved portion 91
at both ends,
in the longitudinal direction, of the curved portion 91.
The attachment portion N2 forms a flat connection face 93. Connecting bolts
94,
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7
embedded in the attachment portion 92 during molding, are projected from the
connection
face 93. The attachment portion ~~2 has a hollow structure like the curved
portion 91.
The bumper beam 90 is t~ced to the vehicle body by tightening a nut (not
shown)
from the inner side of the vehicle body (from the right side in the drawing)
to the bolt 94 at
both attachment portions 92.
In other fixing methods, a method using both the embedded bolt 94 and a U-
shaped bolt 95 together, as illustrated with a double-dolled line in the
drawing, is employed
at both attachment portions 92. 'i'he U-shaped bolt 95 is guided and fixed
into a groove 96
which was previously formed on the opposite side from the connection face 93
of the
attachment portion 92 shown with a double-dotted line in the drawing.
However, in the shock absorbing member for the vehicle, which has the hollow
structure molded by conventional blow molding like the bumper beam 90 shown in
Fig. 16,
the attachment portion 92 as well as the curved portion 91 has the hollow
portion, such that
the connection bolts 94 are embedded, therefore, the shock absorbing member
cannot be
attached to the vehicle body from the outer side of the vehicle (the outer
side of the vehicle
does not imply the traveling direction of the vehicle but rather implies the
side of the outer
area of the vehicle and will imply such from now on), but rather has to be
attached to the
vehicle body from the inner side of the vehicle body (from the side of the
connection face
93), therefore, there is a disadvantage in that a lot of time, work and effort
are needed.
In the bumper beam 90 shown in Fig. 16, for the reason of the thin thickness
of the
attachment portion 92 or for the reason of the inferior workability of fixing
the bumper
beam 90 from the inner side of the vehicle body, instead of a bolt having a
larger diameter
that is impossible to use, a multiple of, For example, three or four, bolts 94
having relatively
smaller diameters have to be used for each attachment portion 92, resulting in
disadvantages
in that the number of parts is incre~ised and attachment wcork is complicated.
Although the aforementioned U-shaped bolts 95 are used, attachment work has to
be carried out from the inner side of the vehicle body, resulting in a
disadvantage in that a
lot of time, work and effort are net:ded similarly.
Further, embedment work. of the bolts 94 when the bumper beam is molded causes
the molding process to be complicated, resulting in the disadvantage of
decreased efficiency
in production.
It is an object of the present invention to provide the resin-made shock
absorbing
member for the vehicle and the method for producing the same, in which the
shock
absorbing member is capable of being easily produced and attached to the
vehicle body, and
having sufficient strength and shock absorbing function.
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Disclosure of the Invention
The present invention is intended to attain the aforementioned object to form
a
solid portion in an attachment portion.
More specifically, a resin-made shock absorbing member far a vehicle according
to
the present invention has properties including an elongated curved portion
having a hollow
portion, and an attachment portion for fixing tco a vehicle body to be united
and thus
continuously formed with the curved portion at both ends in the longitudinal
direction of the
curved portion and to have a hollow portion and a solid portion, at least
extending in the
longitudinal direction of the curved pc7rtion.
The resin-made shock absorbing member for the vehicle according to the present
invention has the property of a bolt hale passing through the attachment
partion therein.
The resin-made shock absorbing member far the vehicle according to the present
invention has the properties of the attachment portion having a flat
connection face attached
to the vehicle body and a concave; portion formed c>n the; opposite side of
the solid portion
from the connection face.
Further, the resin-made shock absorbing member for the vehicle according to
the
present invention has the property of the attachment portion having <~ hollow
portion at each
end, in a direction perpendicular to the longitudinal direction of the solid
portion, of the
attachment portion.
In the resin-made shock absorbing member for the vehicle according to the
present
invention as described thus far, it is advisable to provide an stopping
portion, located on the
inner side of the attachment portion close to the curved portion in the
longitudinal direction
of the shock absorbing member for the vehicle unto the vehicle body.
And, it is advisable that another stopping portion is provided on the outer
side, in
the longitudinal direction of the curved portion extending from the curved
portion, of the
attachment portion, so that the vehicle body is clamped between the stopping
portion and
the aforementioned stopping portion provided on the inner side of the
attachment portion
close to the curved portion.
The concave portion may be spatially surrcaunded by a bottom portion
structured
with the solid portion, side-wall portions extending from both sides of the
bottom portion in
a direction perpendicular to the longitudinal direction of the bottom portion,
and connecting
portions connecting the side-wall portions, and connecting the bottom portion
and a front
face portion formed on the opposite surface from the connection face:.
Further, it is advisable chat the concave portion has sullicient space to bolt
a bolt
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4
inserted through a bolt hole to the vehicle body.
Here, the side-wall portion may be formed to cause the head of the bolt to be
accommodated in the concave portion.
The present invention is a method for producing the resin-made shock absorbing
member for the vehicle as described thus tar, in which the production method
is
characterized by the formation of a hollow portion ot~ the curved portion and
a hollow
portion of the attachment portion by using a hallow parison used in blow
molding, and the
formation of a solid portion of the attachment portion by melting together
parison at each
end, in the longitudinal direction cnf the hollow parison, of the hollow
portion.
Further, it is advisable that the l7at connection face prowided in the
attachment
portion to fix to the vehicle body, and the face formed on the opposite side
of the solid
portion from the connection face, are formed to both correspond to the surface
of a cavity.
Here, materials used for blow molding can be arbitrarily selected from
thermoplastic resin conventionally used as materials for the resin-made shock
absorbing
member far the vehicle, such as a bumper.
For example, the following materials can be used: polypropylene, a high-
density
polyethylene, a linear low-density polyethylene, polyvinyl chloride,
polycarbonate,
polyamide, polyethylene terephthalate, polystyrene, polyoxymethylene, an ABS
resin, an AS
resin, polyphenylene ether, polyphenylene sulfide, ethylene-propylene rubber,
ethylene-
propylene dime three-dimensional rubber, or a compound resin thereof, and a
compound in
which the above resin is added with glass fiber, carbon tiber, talc, mica,
calcium carbonate
and so on as a bulking agent.
But, in order to carry cut blow molding for the resin-made shock absorbing
member for the vehicle which has a specified configuration in a case like the
present
invention, from the view of mechanical strength and molding workability, the
physical
properties of the molding, the shock resistance, the pinch-off strength and so
on, the
preferable material is a compound, a propylene homopolymer whose melt index
(230 °C,
2.16 kgfJ is less than 2.0 g/10 min. and whose isotactic pentad ratio is more
than 93 mole%,
a propylene-ethylene block copolymer which consists of less than 15 wt% of
ethylene per
unit and whose melt index is less than 1.0 g/10 min. and whose isotactic
pentad ratio is
more than 93 mole%, or a polyprc:~pylcne type resin like those of a propylene
homopolymer
and a propylene-ethylene block copolymer, added with another resin, for
example high-
density polyethylene, elastomer, for example an ethylene-propylene type
elastomer, an
ethylene-cx-olefin (except propylene) type elastomer, ~~n cahylcne-propylene-
dime type
elastomer, or one type selected from bulking agents, for example talc.
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Here, it is recommended to use a propylene type polymer in the range of 60-99
wt % , high-density polyethylene in the range of 0-30 wt % , ethylene-a-olefin
type
elastomer in the range of 0-20 wt %, and a bulking agent in the range of 0-40
wt % such as
talc.
5 The compound can be added, as necessary, with thermoplastic resin, such as
polyolefine modified by the derivative of unsaturated carboxylic acid or
modified by
unsaturated carboxylic acid such as acrylic acid and malefic anhydride, with
an inorganic
filler such as calcium carbonate, mica, glass fiber, and carbon fiber, or with
various additives,
such as an antioxidant, an ultraviolet absorption agent, a heat stabilizer, a
sliding agent, a
flame retardant, and a stain.
In the present invention as described thus far, the resin-made shock absorbing
member for the vehicle is attached to the vehicle body at the attachment
portion, therefore,
the impact received to the vehicle is absorbed through the elongated curved
portion and the
attachment portion.
At this time, the curved portion and the attachment portion both have hollow
portions, in which the hollow portion is provided along the whole length of
the resin-made
shock absorbing member for the vehicle, with the result that the shock
absorbing function
can be obtained along the whole length of the member as well as far the resin-
made shock
absorbing member for the vehicle which has the hollow structure by means of
the
conventional blow molding as shown in the aforementioned bumper beam 90 of
Fig. 16.
The solid portion is formed in the attachment portion, whereby embedment work
of the connecting bolt 94 for the attachment portion 92 as shown in the bumper
beam 90 of
Fig. 16 is necessary when the resin-made shock absorbing member for the
vehicle according
to the present invention is fixed to the vehicle body. More specifically, in
the bumper beam
shown in Fig. 16, for the hollow structure of the attachment portion 9?, if
the bumper beam
is attached with the bolt from the outer side of the vehicle, with the bolt
passing through the
hollow portion, then the bolt is unstable, with the result that embedrnent
work of the bolt is
needed, however, this disadvantage is resolved in the present invention.
As a result, by passing the connection means, such as a bolt, a rivet, or a
caulked
projection member (a member projecting from the vehicle body), through the
solid portion
formed in the attachment portic>n, a.ttachment work can be carried out from
the outer side of
the vehicle, namely, from the opposite side of the attachment portion from the
attachment
face, resulting in an easier attachment operation and improved productivity.
For example, when the bolt is used as the connection means along with the bolt
hole passing through the solid portion in the attachment portion, attachment
work can be
CA 02173721 1996-04-17
carried out by inserting and bolting the bolt from the outer side of the
vehicle into the bolt
hole.
Further, when the rivet or the caulked projection member is used as the
connection
means, work crushing the head of the rivet, work opening the legs of a split
rivet, or work
bending and caulking the caulked projection member can be carried out from the
outer side
of the vehicle.
The embedment work of the halt 94 as shown in the bumper beam 90 of Fig. 16 is
not needed, resulting in a simplified molding process and, naturally, improved
productivity.
By being a suitable thickness far the solid portion in the attachment portion,
as
compared with the bumper beam 90 shown in Fig. 16, the number of connecting
bolts can
be reduced, and attachment work can be completed by using two 'bolts, one bolt
for each
attachment portion, whereby the simplified structure, the reduced number of
parts and
easier operation are implemented, resulting in the attainment of the
aforementioned object.
When the attachment portion is structured to be composed of the flat
connection
face attaching to the vehicle body and the concave portion formed on the
opposite side of
the solid portion from the connection face, a part of the connection means
such as the head
of the bolt is to be hidden in the concave portion after connection, whereby
the appearance
of the vehicle can be improved, and the configuration of the vehicle body
corresponding to
the attachment portion of the humher beam is simplified in view of the flat
connection face.
When the attachment portion is structured to have the hollow portion at each
end,
in the direction perpendicular to the longitudinal direction of the solid
portion, the shock
absorbing function working at the attachment portion can be further improved,
resulting in
improved shock absorbing functioning along the whole length of the member.
If the stopping portion is provided on the side of the attachment portion
closest to
the curved portion in order to be Fitted, in the same direct ion as the
longitudinal direction of
the shock absorbing member, attached to the vehicle body, the stopping portion
dampens
force being applied in the longitudinal direction of the resin-made shock
absorbing member
for the vehicle (force being applied in a direction in which both attachment
portions
provided at the ends of the member are moved away i~rom each other by
extending the
curved portion) when the resin-made shack absorbing member for the vehicle
receives an
impact, whereby the shock to the connection portion, between the attachment
portion and
the vehicle body, can be eased, resulting in the reduction c.>f the number of
connection bolts
needed.
Furthermore, another stopping portion is provided on the opposite side, in the
longitudinal direction at the curved portic.~n, of the attachment loortion
from the
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7
aforementioned stopping portion to be further from the curved portion, so that
the vehicle
body can be clamped between the: aforementioned stopping portion provided at
the side of
the attachment portion close to the curved portion ~znd this stopping portion,
whereby the
resin-made shock absorbing memher for the vehicle can be htted when the resin-
made shock
absorbing member for the vehicle is attached to the vehicle body, resulting in
easier
attachment work of the resin-made shock absorbing member for the vehicle.
Incidentally,
the type of stopping portion is not limited, hut the torte being applied in
the longitudinal
direction of the shock absorbing member should be dampened. For example, the
force may
be dampened by a type of stopper, such as a projection for stopping, or a
concave portion
into which the attachment portic7n provided on the vehicle body is inserted.
The concave portion is composed of a bottom portion structured with the solid
portion, side-wall portions extending from both sides of the bottom portion in
a direction
perpendicular to the longitudinal direction of the bcntom portion, and a
connecting portion
connecting the side-wall portions and connecting the bottom portion and a
front face
portion formed on the opposite surface from the connection face, whereby
sufficient room
for attachment can be ensured and, thus, the strength at the attachment
portion can be
increased.
The size of the concave portion is to be sufficient in size, whereby the
bolting work
of the bolt, passing through the bolt hole to the vehicle body, can take place
smoothly and
easily.
Further, the side-wall portion is formed to accommodate the head of the bolt
in the
concave portion, resulting in improved appearance of the vehicle.
The resin-made shock absorbing member for the vehicle according to the present
invention as described thus far can be easily produced by using blow molding.
That is, by
using the hollow parison, the hollow portion formed in the curved portion and
the hollow
portion formed in the attachment portion can be easily formed, and further, by
melting
together parison along parts of both ends, in the longitudinal direction of
the parison, of the
hollow parison, the solid portion formed in the attachment portion can be
easily formed.
The thickness of the solid portion for the attachment portion, which is formed
by
melting together parison as mentioned in the aforementioned description, is
thicker than the
thickness of the attachment portion 92 (which is l~~rmcd with a sheet of
parison) in the
bumper beam 90 shown in Fig. 16, whereby greater strength can be obtained and
the
number of connecting bolts can be reliably reduced.
The flat connection face, which attaches the attachment portion to the vehicle
body,
and the face, which is formed on tl~~; opposite side of the solid portion from
the connection
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face, are formed to coincide with the surface of the cavity, whereby a
necessary parallelism,
which allows easy bolting of the bolt, can be ensured.
Brief Description of Drawings
Fig. 1 is an overall block diagram showing a first embodiment according to the
present invention;
Fig. 2 is a sectional view of a curved portion in the first embodiment;
Fig. 3 is a sectional view of an attachment portion in the first embodiment;
Fig. 4 is an exploded perspective view of the attachment portion in the first
embodiment;
Fig. 5 is a sectional view of a stopping portion of the first embodiment;
Figs. 6 are sectional views of the stopping portion of an experimental example
according to the present invention;
Fig. 7 is an overall block diagram showing a second embodiment according to
the
present invention;
Fig. 8 is an overall block diagram showing the second embodiment which has a
different degree of the gradient of the curved portion than from a shock
absorbing member
for a vehicle shown in Fig. 7;
Fig. 9 is a sectional view showing a first modification according to the
present
invention;
Fig. 10 is a perspective view showing a second modification according to the
present invention;
Fig. 11 is a perspective view showing a third modification according to the
present
invention;
Fig. 12 is a perspective view showing a fourth modification according to the
present invention;
Fig. 13 is a perspective view showing a fxftll modification according to the
present
invention;
Fig. 14 is a perspective view showing a sixth modification according to the
present
invention;
Fig. 15 is a block diagram showing a seventh modification according to the
present
invention; and
Fig. 16 is a perspective view showing a conventional example.
Best Mode for Carrying out the Invention
CA 02173721 1996-04-17
t)
Preferred embodiments of the present invention will now be described with
reference to the drawings. Incidentally, in the description of each of the
following
embodiments, the same reference numerals will be used to designate the same or
similar
components as those in a first embodiment, so that the description is omitted
or simplified.
Fig. 1 shows a manner in which a bumper beam 10 as a resin-made shock
absorbing member for a vehicle of the first embodiment is fixed to a vehicle
body 11.
The bumper beam 10 is of a molding, molded by means of blow molding, and
includes an elongated curved portion 20 extended in the longitudinal direction
of Fig. 1, and
an attachment portion 30, for fixing to a vehicle body, to be united and thus
continuously
formed with the curved portion 20 at both ends, in the Icangitudinal
direction, of the curved
portion 20.
Fig. 2 shows a sectional view of the curved portion 20 taken along the A-A
line in
Fig. 1.
The curved portion 20 has two hollow portions 21 and 22 along each end in a
direction perpendicular to the longitudinal direction of the curved portion 20
(a direction
transverse to the longitudinal direction of Fig. ~).
Further, between those hollow portions 21 and 22, a solid portion 23 is
formed.
The solid portion 23 is formed by fusing together parison by pushing a part of
parison (the
lower portion of Fig. 2) outwards from the outer side of the vehicle body (the
upper portion
of Fig. 2) with dies in the blow molding.
The curved portion 20 continuously has the sectional configuration as seen in
Fig.
2 in the longitudinal direction of the curved portion 20.
Fig. 3 shows a sectional view ol~ the attachment portion 30 taken along the B-
B
line in Fig. 1, and an exploded perspective view of the attachment portion 30
is shown in
Fig. 4.
In Fig. 3, the attachment portion 30 includes a bottom portion 31 formed along
a
part attaching the attachment portion 30 to the vehicle body 11, and side-wall
portions 32
and 33 extending in a direction outwards from the outer side of the vehicle
body (toward
the upper side of Fig. 3) from both ends, in the direction perpendicular to
the longitudinal
direction of the bottom portion 31, of the bottom portion 31. The bottom
portion 31 is a
solid portion formed by melting together parison in the blow molding, and
further, the side-
wall portions 32 and 33 respectively have hollow portions 32A and 33A therein.
In Fig. 4, the attachment portion 30 includes connecting portions 34 and 35
which
are formed to connect the bottom portion 31 <md a front lace 13 of the bumper
beam 10.
The connecting portions 34 and 35 are respectively formed with a sheet of
parison. A
CA 02173721 1996-04-17
portion from the connecting portion 35 to the end of the bumper beam 10 (the
opposite side
of a concave portion 37 from the curved portion 20) is formed to be a hollow
structure.
On the lower surface of the bottom portion 31 in the lower part of Fig. 3, a
flat
connection face 36 is formed to attach and tix to the vehicle body 11.
5 On the opposite side (the outer side of the vehicle) from the connection
face 36
provided in the attachment portion 30, a concave portion 37 is formed to
recess towards the
vehicle body 11. The concave p<~rtion 37 is contained by the bottom portion
31, the side-
walls 32 and 33, and the connection portions 34 and 35.
The bottom portion 31 is provided with a bolt hole 40 formed to pass from the
10 outer side of the vehicle to the connection face 36. A connecting bolt 41
is passed through
the bolt hole 40, a total of two bolts 41 with respect to reach attachment
portion 30, thereby
the bumper beam 10 and the vehicle body 11 are mutually fixed.
Each height S of the side-wall portions 32 and 33 is approximately the same
height
as the curved portion 20, so that the head of the bolt 41 is accommodated in
the concave
portion 37 so as not to project from the line of the front I'ace 13 of the
bumper beam 10 in a
direction outwards from the outer side of the vehicle.
Width L of the concave portion 37 is suiiicient to carry out the bolting work
of the
bolt 41.
Returning to Fig. l, each attachment portion 30 is provided with a fitting
projection (a stopper) 50 as a stopping portion having a hollow structure
projecting towards
the lower side of the drawing at the end of the curved portion 20. The fitting
projection 50
is provided in order to stop the force, which results when the bumper beam 10
moves
toward the vehicle body 11, in the; longitudinal direcaion of the bumper beam
10 when the
vehicle receives an impact.
Fig. 5 shows a sectional view of the fitting projection 50 taken along the C-C
line
in Fig. 1.
The fitting projection 5() is a sectional uneven configuration and includes
two
protrusion portions 51 and 52 at both its ends in a direction perpendicular to
the
longitudinal direction of the fitting projection 50.
In the first embodiment as described thus far, the production of the bumper
beam
10 and the attachment of the bumper beam 10 to the vehicle body 11 will be
described.
First, the bumper beam 10 is produced by means of blow molding by clamping
tubular parison in a molding die (nc~t-shown), having a cavity which is formed
based on the
outer configuration of the bumper beam, with pressure frr~m the outside, and
then, adhering
the clamped tubular parison onto the Burlace of the cavity in the molding die
by expanding
CA 02173721 1996-04-17
11
the parison by blowing air into a hollow portion in the tubular parison.
At this time, by clamping parison with the molding die, the solid portion 23
of the
curved portion 20 is formed by jointly melting together two sheets of parison,
and similarly,
the bottom portion 31 of the solid portion of each attachment portion 30 is
formed.
By blowing air into the hollow portion of the tubular parison in a closed
molding
die state, both end portions, in a direction perpendicular to the longitudinal
direction of the
bumper beam, which has the fitting projections 50 and the hollow portions 21
and 22 of the
curved portion 20, and the side-wall portions 32 and 33 having the hollow
portions 32A and
33A of the attachment portions 30, are formed.
Next, the bumper beam 10 formed as described above is taken out from the die,
and is placed to fit the fitting projections 50 and the connection faces 36 to
the specified
position on the vehicle body 11.
The connecting bolt 41 is inserted tiom the outer side of the vehicle into the
bolt
hole 40, and is bolted from the outer side of the vehicle to fix the bumper
beam 10 to the
vehicle body 11.
According to the first embodiment, the following effects will be listed.
That is, the bottom portions 31, as the solid portions, are provided in the
attachment portion 30, therefore, the bolting work of the bolt 41 can be
carried out from
the outer side of the vehicle by inserting the bolt 41 from the outer side of
the vehicle into
the bolt hole 40 formed to pass through the bottom portion 31.
Accordingly, as compared with conventional attachment work from the inner side
of the vehicle body 11, easier work and increased productivity are attained,
furthermore, an
embedding process of a bolt ~)4 as shown in a conventional bumper beam 90 of
Fig. 16 can
be unnecessary, and naturally, the molding process is simplified, thereby from
this view,
increased productivity can also be attained.
The bottom portion 31 as the solid portion is formed by jointly melting
together
parison, thus, the thickness of the attachment portion can be thicker than an
attachment 92
(formed with a sheet of parison) of the conventional bumper beam 90 shown in
Fig. 16. As
a consequence, the number of bolts can be reduced by using, fbr example, a
bolt having a
relatively larger diameter, that is, as described in the embodiment, the
bumper beam can be
fixed with a total of two bolts 41, one bolt tbr each attachment portion 30,
resulting in a
reduction of the number of parts and simplified work.
Both faces (the cconn~ction face 36 and the bottom face of the concave portion
37)
of the bottom portion 31 are formed to correspond with the surface of the
cavity in the
molding die, thus, a necessary parallelism of both faces easily ensures
bolting of the bolt 41.
CA 02173721 1996-04-17
12
In this case, by forming the surface of the connection face 36 to be higher,
for example, 1-2
mm higher than the surrounding surfaces around the edge of the connection face
36 (to be
projected to the vehicle body 11), the preferred connection face 36 having the
suitable
parallelism with the bottom face of the: ccancave portion :37 can be obtained.
By providing the concave portion 37 in the attachment portion 30, the head of
the
bolt 41 can be accommodated in the concave portion 37, resulting in improved
appearance
of the vehicle.
Width L of the concave portion 37 is sufficient to allow the bolting of the
bolt 41,
resulting in smoother and easier bolting work.
Provision of the fitting projection 50 causes the bumper beam 10 to dampen
force
directed in the longitudinal direction of the bumper beam 10 (force being
applied such that
the distance between the attachment portions 30 formed at both ends of the
bumper beam
10 is longer by extending the bumper beam 10) when the; bumper beam receives
an impact,
whereby the number of connecting bolts can be reduced and the attachment by a
total of
two bolts 41 in this embodiment is allowed.
Further, the hollow portions 21 and 22 are provided in the curved portion 20,
and
also, the hollow portions 32A and 33A are provided in the attachment portion
30, that is,
the hollow portions are provided along the whole length of the bumper beam 10,
whereby
the shock absorbing member can obtain sufficient shock absorbing functioning
along its
whole length similar to that of a conventional resin-made shock absorbing
member for a
vehicle which has the hollow structure molded with conventional blow molding
like the
bumper beam 90 shown in Fig. 16.
In order to ascertain the effect according to the first embodiment, a series
of
experiments using a SMPH Pendulum test were carried out as described below.
In a series of experiments of the hrst embodiment, bumper beams changed, in
regards to height H and thickness T of a stopper as the fitting projection in
a sectional
configuration of Fig. S (Experiments 1 to 6), and bumper beams changed in
regards to
width L2 of each protrusion portic?n formed at both ends of the stopper and
thickness T of
the stopper but fixed a2 15 mm of Height H of the stopper as shown in Figs. 6
(Experiments
7 to 10), were prepared. Furthermore, the overall width L1 of the stopper was
defined as
120 mm.
As a reference example for Experiments 1 to 10, the conventional bumper beam
90
shown in Fig. 16 was assigned.
Resin, used as raw material for the bumper beams in Experiments 1 to 10 and
the
Reference Experiment, is of a resin component with the ti~llowing:
CA 02173721 1996-04-17
13
(1) 65 wt% of polypropylene (made by IDEMITSU PETROCHEMICAL CO., LTD.:
E250G) whose melt index is 1 g/10 min.;
(2) 20 wto'lo of high-density polyethylene (made by IDEMITSU PETROCHEMICAL
CO., LTD.: 75ULB) whose melt index is 0.03 g/10 min.;
(3) 5 wt~/c~ of ethylene-propylene elastomer(made by Japan Synthetic Rubber
Co., Ltd.:
E1?07P) which consists of 73 wt%: of ethylene and has Mooney viscosity of
MLl+4 (100 °
C)=77; and
(4) 10 wt% of a talc whose average particle diameter is 1.5 pm and average
aspect
ratio is 15.
The following are molding conditions and temperature conditions.
[MOLDING CONDITIONS)
MOLDING APPARATUS . 90 mm~
SCREW . 90 mm~
DIE : 100 mm~
ACCUMULATOR . 25 liters
PRESSURE OF CLAMPING DIE . 60 tons
ROTATIONAL FREQUENCY OF SCREW : 40 rpm
LOAD OF MOTOR : 115 .A
[TEMPERATURE CONDITIONS)
CYLINDER No. 1 : 230 °C
No. 2 : 210 °C
No. 3 : 190 °C
No. 4 : 190 °C
CROSSHEAD No. 1 : 190 °C
No. 2 : 190 °C
No. 3 : 190 °C
DIE No. 1 : 19() °C
No. 2 : 19~) °C
MOLDING CYCLE : 200 sec.
TEMPERATURE OF DIE . 2~ °C
TEMPERATURE OF RESIN : 22> °C
The bumper beams (the degree of the gradient a of the curved portion with the
attachment portion is 48°), as an object of Experiments 1 to lU and the
Reference
Experiment, which were molded under the aforementioned conditions, underwent
the
CA 02173721 1996-04-17
14
SMPH pendulum test (impacting speed 8 Km/Hr = S mile/Hr), in which the weight
of the
bumper beam product was 3.5 K~;, the length of the bumper beam product was 1.4
m, the
weight of the vehicle was 1,000 Kg and the temperature was a room temperature,
and a
total evaluation was obtained try checking the maximum degree of deformation,
the
maximum generated load, and a buckling state; of the stopper as to Experiments
1 to 10 and
the Reference Experiment.
The results of the comparative experiments are shown in Table 1 and Table 2,
in
which the results in regard to the Reference Experiment and Experiments 1 to 6
are shown
in Table 1, and the results in regard to Experiments '7 to 10 are shown in
Table 2.
Table 1
RE E1 E2 E3 E4 ES E6
Height of the - 0 S 10 1S 20 2S
stopper :
H mm
Thickness of
the
stopping portion- 4.5 4.0 3.S 3.0 2.3 1.8
:
T mm
Maximum degree 44 6S SS 4S 42 44 49
of
deformation
mm
Maximum generated3.S 2.3 2.6 3.S 3.8 3.4 3.0
load ton
Buckling state bolt X x ~ p-~-Q Q D x -~-L~
of the
sto er came
out
Total EvaluationGood PracticalPractical O timumGood Practical
Good
RE: Reference Experiment E: Experiment
Table 2
Hei ht of the sto er : E 7 ~ E 8 E 9 E 10
H = lSmm _
~
Width of the sto er : L2 < 1S 1S-60 60 > 60
mm
Thickness of the sto in _ < 2.0 2.S-3.1 3.0 3.0
~ ortlon :T mm
Maximum de ee of deformationSO 42 40 S2
mm ~
Maximum enerated load ton 2.9 3.8 3.9 2.8
Buckling state of the stopperx ~-p (~ Q x -yp
Total Evaluation PracticalO timum O timum Practical
E: Experiment
According to Table 1, in Experiments 3 to 5 in which height H of the stopper
was
10 mm to 20 mm, the maximum degree of deformation was small and the maximum
generated load was large, theretore, the. total evrlluation results were Good,
in which
performance can be evaluated to he the same as or higher than the Reference
Experiment.
CA 02173721 1996-04-17
1S
Especially, in the case of Experiment 4 in which height H of the stopper was
15 mm the
result was Optimum. The other Experiments 1, 2 and 6 were inferior in total
evaluation
compared to the Reference Experiment, but were sulticiently Practical. As a
result, it is
understood that the bumper beam can be produced to have higher performance by
adjusting
the height H of the stopper to suitable heights.
According to Table 2, in Experiments 8 and 9 in which width L2 of each
protrusion portion formed at the end of the stopper was 15-60 mm, the maximum
degree of
deformation was small and the maximum generated lead was large, therefore, the
total
evaluation results were extremely Good, in which an improved performance than
the
Reference Experiment was obtained. Experiments ? and 10 were also inferior in
total
evaluation compared to the Reference Experiment, but were sufficiently
Practical. As a
result, it is understood that the bumper beam can be produced to have an
improved
performance by adjusting the sectional configuration of the stopper to
suitable
configurations.
Incidentally, in these experiments, the evaluation was obtained by using only
one
type of component of polypropylene resin, naturally, bumper beams having
higher
performance can be produced by suitably changing a combination of the
conditions, such as
a change of resin and a change in sectional configuration.
From the aforementioned results of the experiment, the bumper beam according
to
the first embodiment can ensure strength and the shock absorbing function with
sufficient
practical usage, namely, the effects of the first embodiment are pronounced.
A second embodiment according to the present invention is explained below with
reference to Fig. ? and Fig. 8.
The second embodiment has a different structure of the end portions of the
bumper
beam and fitting projections from the first embodiment, and hrrther, has a
different degree
of gradient of the curved portion from the first embodiment as shown in Fig.
8, but the
other structures are the same as the first embodiment.
More specifically, a bumper beam 110 of the second embodiment includes an
elongated curved portion 12U extended in the longitudinal direction of Fig. 7,
and an
attachment portion 130, for fixing to a vehicle body, ic7 be united and thus
continuously
formed with the curved portion 12,0 at both ands in the longitudinal direction
of the curved
portion 120.
The curved portion 120 has the same sectional configuration as the curved
portion
20 of the first embodiment. That is, the curved portion 120 has the
akorementioned two
hollow portions 21 and 22 (see Fig. 2) at both ends of the curved portion 120
in a direction
CA 02173721 1996-04-17
16
transverse to the longitudinal direction of the curved portion 12U (a
direction perpendicular
to the plane of the paper in Fig. 7), in which the solid portion 23 (see Fig.
2) is formed
between the hollow portions 21 and 22. The curved portion 120 is parallel to
the vehicle
body 11 at its central portion, and has a degree a of gradient against the
vehicle body 11 at
both ends of the curved portion which connects to the attachment portions 130.
The degree
a of gradient is provided in order that the maximum load is larger when the
bumper beam is
impacted, for example, it is defined at 48° in Fig. 7, and f~4°
in Fig. 8.
The attachment portion J 30 has the same sectional configuration as the
attachment
portion 30 of the first embodiment, and includes the aforementioned bottom
portion 31 and
the aforementioned side-wall portions 32 and 33 (see Fig. 3) extending from
the outer side
of the vehicle body from both ends, in the direction perpendicular to the
longitudinal
direction of the bottom portion 30, of the bottom portion 31, in which the
bottom portion
31 is the solid portion, and the side-wall p<:~rtions 32 and 33 have the
aforementioned hollow
portions 32A and 33A.
The attachment portion 130 has the connecting portions 34 and 35 which are
formed to connect the bottom portion 31 and the front face portion 13 of the
bumper beam
110, in which a portion from the connecting portion 35 to the end of the
bumper beam 110
is formed to be a hollow structure. E3oth extreme ends of the bumper beam in
the
longitudinal direction are formed tc~ curve from the bottom portion 31 in a
direction turning
away from the vehicle body 11.
On the lower surface of the bottom portion 31 in the lower side of Fig. 7, a
flat
connection face 36 is formed to attach and fix to the vehicle body 11, and on
the opposite
side (the outer side of the vehicle) from the connection face 36, provided in
the attachment
portion 130, a concave portion 37 is formed with a recess towards the vehicle
body 11.
The concave portion 37 is contained by the bottom portion 31, the side-walls
32 and 33,
and the connection portions 34 and 35.
The bottom portion 31 is provided with the bolt hole 40, in which the
connecting
bolt 41 is passed through the bolt hole 40, a total of two bolts 41 with
respect to each
attachment portion 130, thereby the bumper beam 110 and the vehicle body 11
are mutually
fixed.
Each attachment portion 130 is provided with a first >~rtting projection (a
stopper)
151 as a stopping portion having a hollow structure to project toward the
lower side of the
drawing at the end of the curved pc~rtic,n 120. The first titting projection
151 is provided in
order to stop the force, which results when the bumper beam 110 moves toward
the vehicle
body 11, in the longitudinal direction of the bumper beam 110 when the bumper
beam
CA 02173721 1996-04-17
17
receives an impact. Further, a second fitting projection 152 as the stopping
portion is
provided on the opposite side, in the longitudinal direction of the curved
portion 120, of the
attachment portion 130 from the first fitting projection 151 to be further
from the curved
portion 120, thereby it is structured that an attachment portion provided on
the vehicle body
11 is clamped between this second lifting projection 1.52 and the first
fitting projection 151
provided on the side of the attachment portion closer to the curved portion.
As a result, in the second embodiment, the following effects are listed in
addition
to the effects described in the first embodiment. More specifically, the
degree a of the
gradient which is formed at each end of the curved portion 12U is relatively
large, whereby
the maximum load of the impact can be heavy. Additionally, it is structured
such that the
second fitting projection 152 is provided on the opposite side, in the
longitudinal direction
of the curved portion 120, of the connection face 3Ei from the first fitting
projection 151, to
be further from the curved portion 120, to be able t<:~ cause the attachment
portion provided
on the vehicle body 11 to be clamped between the seconc.l fitting projection
152 and the first
fitting projection 151 that is provided closer to the curved portion than the
second fitting
projection 152, so that the bumper beam 110 can have its position decided when
being fixed
to the vehicle body 11, resulting in easier attachment work to the vehicle
body 11 for the
bumper beam 110.
In order to verify the effects of the second embodiment, a series of SMPH
pendulum tests and SMPH barrier tests were undertaken as described below.
In these experiments, the attachment of the bumper beam to the vehicle body 11
was carried out by using one bolt 8 mm in diameter and the weight of the
bumper beam
product was 4 Kg. The conditions of the SMPH pendulum tests were based on
those
conditions of the first embodiment. The SMPH barrier tests were undertaken
under the
condition in which the vehicle, weighing 1,000 kg, attached with the bumper
beam impacted
against a concrete wall (impact speed 8 Km/Hr = 5 mile/Hr).
The results are shown in 'liable 3.
Table 3
Hei ht of E 11 E 12
the sto
er : H
= 1S rnm_
The de ree radient of the curved portion48 64
of the cx
Pendulum Maximum generated load fi.0 5.8
Test (ton) 35 38
Maximum degree of deformation7.2 9.0
Barrier mm
Test Maximum =enerated load
ton
Maximum degree of deform;.ttion61 46
mm
Buckling he stopper O
state of J~
t
Tutal Evaluatican Optimum Optimum
-
E: Experiment
CA 02173721 1996-04-17
1H
From the results of the experiment, it is understood that the large degree a
of
gradient which is formed at both ends of the curved portion can cause the
maximum load in
the barrier test to be greater, and the maximum degree of deformation to be
smaller,
resulting in sutlicient shock resistance and an 4ptimurn bumper beam.
Incidentally, it is to be understood that the present invention is not
intended to be
limited to the aforementioned embodiments, and ttie~ other structures capable
of attaining
the object of the present invention, such as variations or modifications set
forth below, are
included in the scope of the present invention.
More specifically, in the aforementioned embodiments, the curved portions 20
and
120 are structured to have the sectional configuration as shown in Fig. 2, but
the sectional
configuration of each curved portion 20 and 120 is arbitrary, such that the
curved portion
may include a part thereof which is parallel to the vehicle body 11 therefore
as long as the
curved portion is curved as a whole in the longitudinal direction, in other
words, there is no
serious disadvantage when the curved portions 20 and 120 are structured to
have the
hollow portion capable of obtaining the required the shock absorbing function.
The attachment portions 30 and 130 are not limited to the structure as
described in
the aforementioned embodiments, hut may be arbitrarily structured as long as
the
attachment portion has the hollow portion and the solid portion, at least
extending in the
longitudinal direction of the curved portions 20 and 120, that is, the
attachment portion can
be structured as described below.
For example, as shown in Fig. y, cancave portions 61 and 62 may be provided,
respectively, on the outer side of the vehicle (the upper side of the drawing)
and on the side
of the bumper beam 10 that is facing the outer side of the vehicle body 11
(the lower side of
the drawing), in which the concave porticm 61 accommodates therein the head of
the bolt
41 and the concave portion 62 may contain a connection face 63 in an
attachment portion
60.
Further, as shown in Fig. 10, an attachment portion 70 may be structured to
have a
hollow portion 71 at the central portion in a direction perpendicular to the
longitudinal
direction and solid portions i2 and 73 on both sides of the hollow portion 71,
and, as
shown in Fig. 11, an attachment portion 75 may be structured to have a hollow
portion 76
on the right or left side of the attachment portion 7S in a direction
perpendicular to the
longitudinal direction and have a solid portion 77 on the ocher left or right
side.
Each attachment portion 30 and 130 has one concave portion 37 in the
aforementioned embodiments, but it is possible for one attachment portion to
be formed
CA 02173721 1996-04-17
19
with multiple concave portions, for example, as shown in Fig. 12, an
attachment portion 80
may be formed by placing multiple concave portions 81 and 82 in a directional
line
perpendicular to the longitudinal direction of the bumper beam 10, and, as
shown in Fig. 13,
an attachment portion 83 may be formed by placing multiple concave portions 84
and 85 in
the same line of direction as the longitudinal direction of the bumper beam
10.
In the aforementioned embodiments, the solid portion being formed in the
attachment portions 30 and 130 is the only solid portion (the bottom portion
31) .formed at
the position extending from the curved portions 2t) and 120, in the
longitudinal direction of
the curved portions 20 and 120, however, in the present invention, the other
solid portions
may be formed in the attachment portion, for example, r~s shown in Fig. 14, an
attachment
portion 86 may be structured to have solid portions 87 and 88, formed to
project from the
position extending from the curved portion 20, in the longitudinal direction
from the curved
portion 20 (the position where the curved portion 20 is extending in the
longitudinal
direction to maintain the width of the curved portion 20) to both sides in a
direction
perpendicular to the longitudinal direction of the curved portion 20, in
addition to the solid
portion (the bottom portion 31) formed at the position extending from the
curved portion
20, in the longitudinal direction of the curved portion 20.
The portion, ti-om the connecting portion 35 formed in the attachment portions
30
and 130 to the end of the bumper beam 10 {the opposite side of the concave
portion 37
from the curved portion 20), is formed to be the hollow portion in the
aforementioned
embodiments, but may be formed to be the solid portion.
The attachment portions 30 and '130 are provided with the fitting projections
(the
stopping portions) 50, 151 and 152 in the aforementioned embodiments, but the
provision
of the fitting projections 50, 151 and 152 can be omitted. However, as seen
from the
aforementioned results of the experiments, it is advisable that the fitting
projections 50, 151
and 152 be provided from the view of strength and the shock absorbing
function.
And, the fitting projections 5t), 151 and 152 are provided at the side of the
curved
portions 20 and 120 on the attachment portions 30 and 130 in the
aforementioned
embodiments, but, as shown in Fig. 15, the fitting projection may be formed as
a fitting
projection 89 provided at, approximately, the end of the attachment portion
30. The
stopping portion is defined as the hitting projections 50, 151 and 152 in the
aforementioned
embodiments, but, in the present invention, the stopping portion may be formed
as a
concave portion, capable of accommodating the attachment portion, provided in
the vehicle
bo dy.
In the aforementioned embodiments, the foetal number of bolts 41 being used is
two,
CA 02173721 1996-04-17
with one bolt for each of the two attachment portions 3(), at the ends of the
curved portion
20, and the two attachment portions 130, at the ends of the curved portion
120, but, more
than a total of two bolts can be used fijr bolting. However, it is desirable
that the number of
bolts used be kept to a minimum in view of a reduction of the number of parts
and of
5 simplified work.
The bumper beams 10 and 110 are produced by blow molding in the
aforementioned embodiments, however, the resin-made shock absorbing member for
the
vehicle of the present invention can be produced by other methods for molding
as long as
the molding method can ensure the requested configuration, such as a gas
injection molding
10 method (a hollow injection molding method).
The resin-made shock absorbing member for the vehicle is explained as it
applies to
the bumper beams 10 and 110 in the aforementioned embodiments, however, the
resin-made
shock absorbing member for the vehicle can he applied to a bumper, a side
protector and so
on.
Industrial Availability
The present invention can be used as a general member capable of absorbing
shock
forces applied to the outer side of the vehicle by providing the vehicle with,
for example, a
bumper beam, a bumper, and/or a side protector.
