Impact-absorbing transverse support arrangement

A transverse support arrangement, consisting of two support sections extending parallel to one another, both of which have closed cross-sections and a common wall, is made in one piece as an extruded member and, in addition, is designed so that, upon impact, a conversion of energy is effected by reverse deformation of a support section.

BACKGROUND OF THE INVENTION 
This invention relates to impact-absorbing transverse support arrangements, 
for example, of the type used to absorb collision-generated impact forces 
in motor vehicles. 
Transverse support arrangements for absorbing impact forces are generally 
designed to absorb forces applied in a direction transverse to the 
longitudinal extent of the member. Accordingly, in the preferred 
application of the invention, i.e., the absorption of collision-generated 
impact forces in motor vehicles, this transverse support arrangement may 
constitute a component of a shock absorber, a knee bar, a sill, a door 
column, a ramming buffer or any other transverse support arrangement 
which, in the event of a collision, is subject to impact forces produced 
by an external object or by the inertia of passengers in the vehicle. 
Particularly in the preferred application of the invention, it is important 
that the transverse support arrangement is not simply preserved upon the 
occurrence of impact forces, but that it is capable of converting the 
kinetic energy of the impact forces into deformation work. In other words, 
the transverse support arrangement should be designed so that its 
cross-section can be deformed upon application of impact forces. In 
addition, in the preferred application of the invention, namely, in motor 
vehicles, it is necessary to convert the impact energy into deformation 
work to the greatest possible extent in a short deformation path. This is 
especially true when the transverse support arrangement is arranged along 
the side of a vehicle or is positioned as a knee bar in the knee room of 
the vehicle, since the space required for long deformation elements is not 
available in those cases. 
A transverse support arrangement of this type is disclosed in U.S. Pat. No. 
4,893,834 in the form of a knee bar having two adjacent transverse support 
sections, the first of which has a closed rectangular cross-section and 
the second having an essentially open semicircular cross-section which is 
attached to the body of the automobile by flanges at the open side of its 
cross-section. Because of the continuous curvature of the cross-section of 
the second section, the latter forms a linear support, extending parallel 
to the longitudinal direction of the first support section, and providing 
a support surface for the closed rectangular first support section. The 
first support section has a very rigid design in comparison to the second 
support section since it is intended to distribute the locally 
concentrated compressive forces produced by impact of the knee of a 
passenger in the vehicle as a result of a collision over as large a 
longitudinal portion of the second support section as possible. Because 
the width of the first support section is less than that of the second 
support section, deformation of the second support section takes place 
essentially by reverse deformation of the side walls of that section in 
such a way that the first section is pressed into the body of the second 
section. 
This conventional transverse support arrangement has several disadvantages. 
For one thing, the use of a second support section having an open 
cross-section with flanges requires the presence of parts on the 
automobile body to which the flanges of the second support section are 
attached and, accordingly, necessitates appropriate design of these body 
parts. Secondly, the manufacture of this conventional transverse support 
arrangement is exceptionally cumbersome and costly since the two support 
sections are made in separate operations and are then joined together by 
screws. These screw connections require the second support section to have 
an open cross-section since otherwise it would hardly be possible to 
provide the screw connections. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a 
shock-absorbing transverse support arrangement which overcomes the 
above-mentioned disadvantages of the prior art. 
Another object of the invention is to provide a shock-absorbing transverse 
support arrangement which is self-enclosed so that it need only be 
properly supported in its application in motor vehicles and which can be 
produced by a simple mass-production method, while preserving the 
advantages of the prior art arrangement. 
These and other objects of the invention are attained by providing a 
transverse support arrangement having two sections formed with a common 
wall and having closed cross-sectional configurations, with one of the 
sections having a width greater than that of the other section, the 
structure being produced by a one-piece extrusion. 
An essential concept of the invention is that the transverse support 
arrangement can be produced as a homogeneous part by extrusion, so that 
the transverse support arrangement constitutes a strip which only needs to 
be cut to the length required for its specific application. This 
advantageous production possibility is not obtained at the expense of 
properties important for the absorption of impact forces or of 
possibilities for variation in the structure of the transverse support 
arrangement because the properties of rigidity which are advantageous for 
useful conversion of kinetic energy into deformation work may be imparted 
to the individual walls of the transverse support arrangement in the 
extrusion. This means that short peaks ("spikes") of force in the 
force-distance diagram or in the force-time diagram are prevented and, 
instead of this, a fairly large region having an approximately constant 
force gradient is provided.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring first to the typical embodiment shown in FIG. 1, a foam pillow 1 
is mounted in front of a first support section 2 which, in turn, is 
disposed in front of a second support section 3 in the direction of an 
impact force, for example, in the direction of a passenger's knee moving 
forward in case of collision of the vehicle. In this case, the second 
support section 3 is supported on at least the A columns of the vehicle. 
The first support section 2 has a rectangular cross-section of greater 
width (i.e., height when disposed horizontally) than depth, and a 
rectangular cross-section is likewise provided for the second support 
section 3. Thus, the second section also has a closed and hence sturdy 
cross-section. Two surfaces 4 and 5 of the two sections 2 and 3, 
respectively, which are on opposite sides of a common wall 6, have a 
different height. In addition, the connecting walls 7 and 8 of the second 
support section 3 are oppositely inclined to form a trapezoid so that the 
height of the second support section 3 increases with increasing distance 
from the common wall 6. In addition, the thickness of the two walls 7 and 
8 increases continuously in that direction. If desired, the rigidity of 
the support arrangement in the longitudinal direction may be made 
discontinuous by providing recesses and/or foam fillings. 
The entire transverse support arrangement consisting of the integral 
support sections 2 and 3 constitutes a one-piece double-chamber extrusion 
support section which is supplied as a strip. 
Preferably, the transverse support is made of aluminum, but the use of 
synthetic material with reinforcements of metal or fiber composite is 
alternatively possible, especially for the walls 7 and 8. 
Referring to FIG. 2, if an impact force F of predetermined minimum 
intensity occurs, the cross-sectional shape of the first support section 2 
is at least initially maintained and that section is forced into the 
second section 3. This produces a reverse deformation of the second 
section in the sense that the common wall 6 of the two sections 2 and 3 is 
moved into the second section 3. This reverse deformation is completed 
when the common wall 6 engages the wall 9, at the right in the figures, of 
the second section 3. An additional conversion of energy may take place 
during a final phase of deformation of the second section 3, or subsequent 
thereto, by deformation of the first section 2, so that practically the 
entire original dimension of the transverse support sections 2 and 3 in 
the direction of impact F is utilized as a deformation distance. 
As a general principle, a plurality of the support sections may 
alternatively be combined behind one another in the direction of impact 
and/or, with reference to the illustration of FIG. 1, in front of one 
another in an extruded impact-absorbing section. 
Accordingly, the invention provides a transverse support arrangement which 
may be produced very simply and which has optimum properties with respect 
to the absorption of impact stresses. 
Although the invention has been described herein with reference to specific 
embodiments, many modifications and variations therein will readily occur 
to those skilled in the art. Accordingly, all such variations and 
modifications are included within the intended scope of the invention.