Shock absorbing assembly

A shock absorbing assembly disclosed such as an over rider of a bumper, a shock absorbing bumper, a stopper or a guard molding, comprises a core member or members molded of a low density elastomeric material having stud bolts or nuts inserted before molding and embedded therein, and a cover member molded of a high density elastomeric material enclosing the core member inserted before molding the cover member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a shock absorbing assembly such as an over 
rider of a bumper, a bumper guard, a body side molding, a stopper or the 
like. 
2. Description of the Prior Art 
A shock absorbing assembly of this kind hitherto used, for example, a 
bumper guard comprises, as shown in FIG. 1, a main body 1 of a unitary 
shock absorbing member of an elastomeric high molecular compound and 
mounting stud bolts 2 embedded therein which are inserted in the bottoms 
of the main body when it is molded. The main body 1 includes a cavity 3 
except the embedded portions 1a for the stud bolts 2, which are connected 
by a thin connection portion 1b. With this arrangement, the bumper guard 
is secured to a bumper 5 shown in phantom lines by means of the stud bolts 
2 and nuts 4. 
With this construction, however, there are following various disadvantages 
because the embedded portions 1a are unavoidably solid over from outer 
surfaces to the mounting bottoms. 
(1) The material of the main body of the bumper guard is bulky which is 
disadvantageous in weight and cost. 
(2) The difference in thickness between the thick embedded portions 1a and 
thin connection portion 1b causes a difference in cooling temperature 
between them when molding, resulting in shrinkage cavities on outer 
surfaces of the embedded portions 1a. 
(3) The bulky main body requires a long period of time for the molding 
cycle. 
(4) A range of hardness of the material of the main body to be adjusted for 
obtaining a required load characteristic is limited for the purpose of 
preventing surface defects of the main body. 
(5) A hollow center portion for the purpose of avoiding an extra thickness 
is apt to be reversely tapered, so that a construction of the mold is 
complicated. 
SUMMARY OF THE INVENTION 
It is a principal object of the invention to provide an improved shock 
absorbing assembly which eliminates all the disadvantages of the prior 
art. 
In order to accomplish this object, the shock absorbing assembly according 
to the invention comprises at least one core member molded of a low 
density elastomeric material including fastening means for mounting the 
assembly such as stud bolts, nuts or the like inserted before molding and 
embedded therein, and a cover member molded of a high density elastomeric 
material enclosing therein said core member inserted before molding said 
cover member. 
In order that the invention may be more clearly understood, preferred 
embodiments will be described, by way of example, with reference to the 
accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 2 illustrates core members 11 of a low density foam elastomeric 
material such as uretane foam previously molded having at their bottoms 
respective mounting stud bolts whose heads are embedded therein. As shown 
in FIG. 3, the core members 11 are inserted into a mold in which a cover 
member 13 of a high density elastomeric high molecular compound such as 
RIM urethane is then molded so as to enclose the core members 11 to obtain 
an over rider including a space 14 between the cover member 13 and core 
members 11, whose external appearance is substantially the same as that of 
the main body 1 of the bumper guard of the prior art (FIG. 4). 
The energy absorbing characteristic of the core members 11 can be 
controlled at will by changing the foaming amount and configuration of the 
core members. The cover member 13 is preferably formed so as to be uniform 
in thickness particularly taking care of strength, surface hardness, 
appearance and quality. The over rider thus obtained is clamped to a 
bumper 17 shown in phantom lines in FIG. 3 by means of nuts 16. 
Instead of the stud bolt 12, a box nut 18 may be embedded in the core 
member 11 as shown in FIG. 5. 
FIG. 6 illustrates other embodiment wherein the present invention is 
applied to a shock absorbing bumper 19. In this case, a unitary core 
member 11 is covered by a cover member 13 without including a space 14. 
This shock absorbing assembly as a bumper is secured to a back bar 20 by 
means of embedded bolts 12 for mounting the bumper to a vehicle body. 
FIG. 7 illustrates a further embodiment wherein the present invention is 
applied to a stopper 21. A unitary core member 11 is covered by a cover 
member 13 without a space 14 in the similar manner to FIG. 6. In this 
embodiment, the core member 11 is formed with a number of anchoring 
grooves 11a, while the cover member 13 is internally formed with a number 
of ridges 13a engaging the anchoring grooves 11a of the cover member 11. 
FIG. 8 illustrates a further embodiment, wherein the present invention is 
applied to a guard molding (or bumper guard) 22. A unitary core member 11 
is covered by a cover member 13 without a space 14 as the above 
embodiments. 
In any of the embodiments above described, after the core members have been 
molded, it is only required for integrally forming the core and cover 
members to arrange the molded core in a mold when the cover member is 
molded. 
As can be seen from the above description, the shock absorbing assembly 
according to the invention comprises a core member or members molded of a 
low density elastomeric foam having fastening means such as mounting stud 
bolts or nuts inserted before molding and embedded therein, and a cover 
member molded of an elastomeric high molecular compound enclosing the core 
member or members inserted before molding and embedded therein, thereby 
achieving the following advantages. 
(1) The most part of the shock absorbing assembly is composed of a foam 
material to lighten the entire weight. 
(2) The energy absorbing characteristic of the shock absorbing assembly can 
be effectively determined because the hardness of the core member can be 
widely adjusted by selecting the foaming extent and configuration of the 
core member 11. 
(3) The cover member 13 can be formed substantially uniformly in thickness, 
so that there is no shrinkage cavity on its surface to provide a much more 
aesthetical appearance and a high quality. 
(4) The core members 11 are inserted in portions to be hollow, so that the 
mold does not have inverse tapered portions and therefore the construction 
of the mold is simplified. 
(5) The cover member 13 is thin and uniform in thickness which shorten the 
time required for curing the cover member and hence the molding cycle, 
thereby improving the productivity and reducing the cost. 
(6) The mounting stud bolts or nuts embedded in the core members 11 molded 
of the low density elastomeric foam can easily be aligned even if their 
directions are not in desired directions. The mounting operation can 
easily be effected. 
It is further understood by those skilled in the art that the foregoing 
description is preferred embodiments of the disclosed assembly and that 
various changes and modifications may be made in the invention without 
departing from the spirit and scope thereof.