Shock absorbing bumper for vehicles

A shock absorbing bumper for vehicles comprises an elongated bumper body which includes an outer layer formed of synthetic resin material by extrusion molding and an absorbing internal central bumper portion disposed internally of the outer layer, the internal central bumper portion has a plurality of axial bores and web portions.

BACKGROUND AND SUMMARY OF THE INVENTION 
This invention relates to a shock absorbing bumper for vehicles, and more 
particularly to such a bumper as made mainly of plastic material. 
Various types of shock absorbing bumpers made of synthetic resin material 
have heretofore been proposed, for instance in U.S. Pat. Nos. 4,134,610 to 
Lindewall and 3,666,310 to Burgess et al. However, many of those 
conventional bumpers are of such a construction as does not permit 
production by continuous extrusion molding, resulting in a high 
manufacturing cost. Further, many of the conventional plastic or rubber 
made shock absorbing bumpers are common in such a basic idea that the 
major impact forces imposed on a vehicle bumper are absorbed mainly by the 
elastic property of an employed specific material such as foamed 
polyurethane or rubber, or by cushioning effect of fluid confined in an 
elongated chamber or a tube disposed within a bumper body, as disclosed, 
for example, in U.S. Pat. Nos. 3,690,710 to Curran, 3,829,141 to Igwe, 
3,734,557 to McKenzie, and 3,938,840 to Haase et al in addition to the 
above referred U.S. Pat. Nos. 4,134,610 and 3,666,310. However, the idea 
of the present invention is distinguishable from the afore-discussed 
conventional idea in such a point that shock absorption is attained mainly 
by a specific, internal mechanical structure of a bumper body. 
Accordingly, an object of the present invention is to provide a shock 
absorbing bumper formed mainly of synthetic resin material by continuous 
extrusion molding. 
Another object of the invention is to provide a shock absorbing bumper 
which has an outer layer of synthetic resin material and an internal 
central bumper portion which includes a plurality of axial bores and web 
portions. 
Other objects, features and advantages of the present invention will become 
more apparent from the following detailed description taken in connection 
with the accompanying drawings; it should be understood, however, that the 
detailed description and specific examples, while indicating preferred 
embodiments of the invention, are given by way of illustration only, since 
various changes and modifications within the spirit and scope of the 
invention will be apparent to those skilled in the art from this detailed 
description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, in particular to FIGS. 1 to 14, wherein each 
of the reference numerals without an alphabetic letter is used to 
generally indicate an element of the present invention, while each of 
reference numerals with a certain alphabetic letter is used to indicate a 
certain specific embodiment of the element generally indicated by the same 
reference numeral without any alphabetic letter. For example, reference 
numeral 10 is used to generally indicate an elongated bumper body of the 
invention, while each of reference numerals 10a, 10b, 10c, etc. is used to 
indicate each of the specific embodiments of the bumper body 10. 
The shock absorbing bumper according to the present invention includes the 
elongated bumper body 10, a pair of end members 11 each of which is 
secured to a respective end of the bumper body 10 preferably by adhesive, 
and a metal support 12 on which the bumper body 10 is conventionally 
mounted. 
The bumper body 10 has an outer layer 13 and an internal central bumper 
portion 14 which is disposed internally of said outer layer 13. The outer 
layer 13 may be formed of a suitable synthetic resin material such as 
polyethylene, polyvinyl chloride, polypropylene, nylon, acrylonitrile 
butadiene styrene (ABS), or fiberglass reinforced thermoplastics, by 
continuous extrusion molding and then cutting into pieces of a desired 
length. 
The internal central bumper portion 14 has wide variations. For example, 
the central bumper 14 may be formed of the same semi-rigid, slightly 
elastic synthetic resin material of which the outer layer 13 is formed, by 
the same extrusion molding and cutting process, so that the outer layer 13 
and the central bumper 14 are a single piece of an elongated integral body 
as particularly shown in FIGS. 5 to 11. Otherwise, the outer layer 13 may 
be formed on a prepared central bumper 14, as particularly shown in FIGS. 
12 to 14. Further, the material of which the central bumper 14 is formed 
should not be limited to a synthetic resin, but aluminium or alloys 
thereof may be employed. 
The central bumper 14 is characterized in that it includes a plurality of, 
preferably at least four, axial bores 15 extending through the entire 
length of the central bumper 14, and web portions 27 disposed among the 
axial bores 15. The number, size, shape in cross section, and distribution 
of the bores 14 and the web portions 27 may be varied in many ways as 
shown in various embodiments to be described hereinafter. 
The end members 11 may be formed of a suitable synthetic resin material 
similar to or the same as the material of which the outer layer 13 is 
formed. The end member 11 may be formed into various constructions. For 
example, the end member 11a may be so constructed that the axial bores 15 
of the central bumper 14 are not closed by any wall of the member 11a but 
are communicated with the atmosphere, as shown in FIG. 2. It is also 
possible to construct the member 11 so that, as shown in FIG. 3, a wall 16 
thereof can hermetically seal the end openings 15' of each axial bore 15. 
Otherwise, as shown in FIG. 4, the member 11c may be formed with narrow 
holes 17 which are in communication with the axial bores 15 of the central 
bumper 14. 
FIG. 5 illustrates the first embodiment 10a of the bumper body 10, in which 
the outer layer 13a and the internal central bumper portion 14a are 
integrally formed of the same semi-rigid, slightly elastic synthetic resin 
material by continuous extrusion molding. The internal 14a is formed with 
a plurality of regularly disposed axial bores 15a of uniform size each of 
which is round in cross section. The internal 14a is further formed with 
web portions 27a among the bores 15a. 
FIG. 6 shows the second embodiment 10b of the bumper body 10 in which the 
outer layer 13b and the central bumper portion 14b are also integrally 
formed of the same semi-rigid, slightly elastic synthetic resin material 
by extrusion molding. The central bumper 14b is formed with web portions 
27b and a plurality of axial bores 15b each of which is hexagonal in cross 
section. 
FIG. 7 shows the third embodiment 10c, in which the outer layer 13c and the 
central bumper 14c are also integrally formed of the same material by 
extrusion molding. The central bumper 14c is formed with web portions 27c 
and a plurality of axial bores 15c each of which is rectangular in cross 
section. 
In the above described embodiments 10a, 10b, 10c, it is obvious that shapes 
in cross section of the axial bores 15a, 15b, 15c may be varied into 
various other shapes such as oval, triangular, square or other regular or 
irregular polygonal shapes. 
FIG. 8 shows the fourth embodiment 10d of the bumper body 10, in which the 
outer layer 13d and the internal 14d are also integrally formed of the 
same semi-rigid, slightly elastic synthetic resin material by extrusion 
molding. The axial bores 15d of the central bumper 14d are distributed in 
three groups. However, the number of the groups should not be limited to 
three but may be two, four or more. Further, the number of the bores 15d 
of each group may be varied in many ways. The central bumper 14d has web 
portions 27d disposed among the bores 15d. 
FIG. 9 illustrates the fifth embodiment 10e of the bumper body 10, in which 
the outer layer 13e and the central bumper 14d are also integrally formed 
of the same semi-rigid, slightly elastic synthetic resin material by 
extrusion molding. The internal 14e has web portions 27e and a plurality 
of axial bores 15e which are different in size. A reinforcing pipe 18e 
made of aluminium, aluminium alloy, or a rigid synthetic resin material 
extends through one or more of the bores 15e. 
FIG. 10 shows the sixth embodiment 10f of the bumper body 10, in which the 
outer layer 13f and the central bumper 14f are also integrally formed of 
the same synthetic resin material by extrusion molding. The central bumper 
14f has web portions 27f and a plurality of axial bores 15f. Each of the 
bores 15 is internally provided with a reinforcing pipe 18f made of 
aluminum or an aluminium alloy, or a rigid synthetic resin material. 
FIG. 11 shows the seventh embodiment 10g of the bumper body 10, in which 
the outer layer 13g and the central bumper 14g are also integrally formed 
of the same synthetic resin material by extrusion molding. The central 
bumper 14g includes web portions 27g and a plurality of axial bores 15g. 
Each of the bores 15g is triangular in cross section. If desired, the 
bumper body 10g may be further provided with an axial hollow space 19g 
which is filled with foamed plastic 20g such as foamed urethane. 
FIG. 12 illustrates an eighth embodiment 10h of the bumper body 10, in 
which the outer layer 13h is formed on a prepared central bumper 14h. In 
this embodiment, it is possible to form the outer layer 13h and the 
central bumper 14h from different materials. For example, the outer layer 
13h may be formed of abrasion resisting synthetic resin such as 
polyethylene, while the central bumper 14h may be formed of somewhat hard 
and somewhat elastic material such as polyvinyle chloride or hard rubber. 
The central bumper 14h includes a plurality of axial bores 15h and web 
portion 27h. 
FIG. 13 shows the ninth embodiment 10i of the bumper body 10, in which the 
outer layer 13i and the central bumper 14i are formed by separate 
processes. The central bumper 14i is in the form of a bundle of pipes 21 
each having an axial bore 15i. Each of the pipes 21 may be made of rigid 
or semi-rigid synthetic resin material or aluminum or an aluminum alloy. 
Walls of the pipes 21 cooperate to form web portions 27i of the central 
bumper 14i. 
FIG. 14 shows the tenth embodiment 10j of the bumper body 10, in which the 
outer layer 13j and the central bumper 14j are also formed by separate 
processes. The central bumper 14j is in the form of a tubular member 22 
made of aluminum or an aluminum. The tubular member 22 has a framework 
including a plurality of concentric tubular walls 23, 24, 25 and a 
plurality of radially extending walls 26, providing a plurality of axial 
bores 15j defined by said walls 23, 24, 25 and 26 which serve as web 
portions 27j. It is readily apparent that the specific construction of the 
framework 22 may be varied in many ways. 
In operaton, when impact forces are imposed on the bumper body 10, the 
outer layer 13 and the web portions 27 of the central bumper 14 cooperate 
to resist the impact forces. At the same time, the outer layer deforms, 
while the web portions 27 flex in view of the existence of the axial bores 
15, thereby absorbing the impact forces to a certain extent. Further, 
owing to the specific structure of the central bumper 14 described 
hereinbefore, the impact forces imposed on the front wall of the bumper 
are gradually decreased before they are finally transmitted to the 
metallic support 12. 
In case the end openings 15' of each axial bore 15 are hermetically sealed 
by the end members 11b as illustrated in FIG. 3, shock absorbing effect 
can be enhanced by the known air cushioning function of the air confined 
in the bore 14. This advantage can also be obtained to a certain extent by 
the embodiment shown in FIG. 4 in which the narrow holes 17 are formed in 
each of the end members 11c. 
The present invention being thus described, it will be obvious that same 
may be varied in many ways. Such variations are not to be regarded as a 
departure from the spirit and scope of the present invention, and all such 
modifications as would be obvious to one skilled in the art are intended 
to be included within the scope of the following claims.