Bumper for motor vehicles having a shock-absorbing profile

A bumper for motor vehicles with a cross bearer at least indirectly supported at the vehicle frame and constructed essentially as closed hollow profile and with an elastically yielding impact-absorbing profile member essentially U-shaped in cross section which is detachably and form-lockingly secured at the cross bearer on the impact-endangered side thereof; the U-shaped profile is thereby clamped with its leg ends over its entire length between web-like mounting edges extending in the longitudinal direction of the cross bearer, on the one hand, and corresponding lateral web-like mounting edges of a clamping bar also extending in the longitudinal direction and secured to the cross bearer, on the other; the web-like mounting edges of the cross bearer extend at least approximately perpendicularly to the legs of the U-shaped profile member and engage in corresponding longitudinal grooves of the U-shaped profile member provided on the inside of the leg ends; the clamping bar which is constructed as bearer channel surrounding the cross bearer on the backside thereof and which is stabilized together with the same in its cross-sectional shape, presses with its lateral longitudinal edges the leg ends of the U-shaped profile externally against the cross bearer.

The present invention relates to a bumper for motor vehicles with a cross 
bearer at least indirectly supported at the motor vehicle frame and 
constructed essentially as closed hollow profile and with an elastically 
yielding, shock-absorbing profile member essentially U-shaped in cross 
section and detachably and form-lockingly secured at the cross bearer on 
the impact-endangered side thereof, whereby the U-shaped profile member is 
clamped with its leg ends over its entire length between web-like mounting 
edges extending in the longitudinal direction of the cross bearer and 
arranged at circumferential places of the cross bearer that face the 
U-shaped profile member and are located as far in the direction toward the 
U-shaped profile member as possible, on the one hand, and corresponding 
lateral web-like mounting edges of a clamping bar also extending in the 
longitudinal direction and fastened against the cross bearer by 
clamping-type fastening means, on the other. 
Such a bumper is the subject matter of an earlier application. In this 
prior application, longitudinal bulges at the ends of the U-shaped profile 
member were spread apart by a clamping bar arranged on the inside of the 
profile member between web-like mounting edges of the cross bearer 
inclined wedge-shaped toward one another, similar to the manner in which 
the radially inner beads of an automobile tire are pressed into the flanks 
of a rim bed. For this purpose, the clamping bar has to be provided with 
several tie-rods extending through the cross bearer in the impact 
direction. This creates certain problems of the stress introduction and of 
the force distribution from the tie-rods into the clamping bar. 
Furthermore, the clamping bar becomes somewhat complicated from a 
manufacturing point of view due to the tie-rods and the described stress 
introduction. As to the rest, the clamping bar is a relatively large and 
heavy structural part which, however,--apart from its own slight inherent 
rigidity--does not itself contribute significantly to the rigidity and 
strength of the bumper. As to the rest, the clamping bar can be deformed 
by the impacts which penetrate the elastic profile up to the base because 
it is arranged on the impact-endangered side of the cross bearer. 
It is the aim of the present invention to eliminate the described 
disadvantages. This is achieved according to the present invention in that 
the web-like mounting edges of the cross bearer extend at least 
approximately perpendicularly to the legs of the U-shaped profile member 
and engage in corresponding longitudinal grooves of the U-profile provided 
on the inside of the leg ends, and in that the clamping bar is constructed 
as bearer channel having a large profile dimension in the impact direction 
which surrounds the cross bearer on the backside thereof and is stabilized 
therewith in its cross-sectional shape, whereby the bearer channel presses 
with its lateral longitudinal edges the leg ends of the U-shaped profile 
member externally against the cross bearer. 
The clamping bar constructed as bearer channel, by the rearward arrangement 
thereof at the cross bearer, is removed from the impact access. The 
clamping bar receives a bearer function by the large web height of the 
clamping bar in the impact direction and by the stabilization effected by 
means of the cross bearer as regards its cross-sectional shape and can be 
incorporated in the dimensioning of the cross bearer. As a result thereof, 
the cross bearer can be constructed more lightweight and/or less high in 
the impact direction. The clamping bar can be constructed as simply 
punched-out and apertured sheet metal without special measures for the 
stress introduction of tie-rod forces. The form-locking engagement between 
the U-shaped profile member and the cross bearer also withstands strong 
loads and deformations of the U-shaped profile. 
For the purpose of better impact absorption and load distribution onto the 
cross bearer in the width dimension, it is appropriate if the U-shaped 
profile is provided on the inside with a large number of cross ribs and if 
the front face of the cross bearer is constructed as support plate for the 
cross ribs. The cross ribs connecting the legs with each other may support 
themselves with their inner end edges at the support plate in case of an 
impact and may thus transmit the impact force into the cross bearer by way 
of a large surface. The deformation of the cross-ribs serves the impact 
absorption. 
Accordingly, it is an object of the present invention to provide a bumper 
for motor vehicles having an impact-absorbing profile which avoids by 
simple means the aforementioned shortcomings and drawbacks encountered in 
the prior art. 
Another object of the present invention resides in a bumper for motor 
vehicles having an impact-absorbing profile which is simple in 
construction and highly effective for its intended purposes. 
A further object of the present invention resides in a bumper for motor 
vehicles with an impact-absorbing profile in which the various parts can 
be easily manufactured and assembled and which utilizes relatively 
lightweight parts. 
A still further object of the present invention resides in a bumper of the 
type described above which exhibits high rigidity and strength and which 
assures an improved absorption and load distribution of the resulting 
forces.

Referring now to the figures of the drawings, the bumper in accordance with 
the present invention essentially consists of two parts, namely of a cross 
bearer generally designated by reference numeral 1 secured at the vehicle 
frame and of an elastic impact-absorbing profile member generally 
designated by reference numeral 2 of essentially U-shaped cross section 
which is detachably and form-lockingly secured on the impact-endangered 
side of the cross bearer, whereby the impact direction is indicated by 
arrow 3. 
The cross bearer 1 which is threadably connected at the frame (not shown) 
of a motor vehicle by way of the bent flat bars 4, is constructed as 
hollow bearer. It is composed of several parts, and more particularly at 
first of the hollow bearer 5, properly speaking, and of the rearward 
clamping bar 6 for the U-shaped profile which serves as bearer 
reinforcement. The hollow bearer 5, properly speaking, includes in the 
illustrated embodiment a rectilinear support plate 7 facing the U-shaped 
profile member, the function of which will be described more fully 
hereinafter. A channel- or trough-shaped steel metal profile member 8 is 
welded by means of its lateral flanges to the lateral edges of the support 
plate 7, whence the hollow profile member 5 results. Web-like mounting 
edges 9 extending in the longitudinal direction of the cross bearer 5 will 
result at the top and at the bottom of the cross bearer 5 by reason of the 
welded connection of the flanges. These mounting edges 9, on the one hand, 
are arranged at the cross bearer 5 perpendicularly to the impact direction 
3 by reason of the rectilinear construction of the support plate 7 and, on 
the other, are arranged in the illustrated cross section at those 
circumferential places of the cross section which are disposed as close to 
the U-shaped profile 2 as possible. 
The rear portion of the hollow bearer 5, as viewed in the impact direction 
3, is covered by a channel- or trough-shaped clamping bar 6 which closely 
surrounds the hollow bearer 5 and is threadably connected with the same by 
the use of welded-on nuts 11 and bolts 10, whereby the open profile which 
is inherently labile and unstable, is stabilized in its shape. The 
clamping bar 6 has a large profile dimension H in the impact direction 3 
so that it exhibits a high bending strength by reason thereof and by 
reason of its sturdy shape. It therefore contributes considerably to the 
bending strength of the entire cross bearer 1. The edges of the clamping 
bar 6 are strongly reinforced and stiffened by crimping, corrugations or 
beads, from which results a high edge rigidity. However, above all, the 
edge portions are so selected that a good edge clamping action will result 
for the impact-absorbing U-shaped profile 2 to be described more fully 
hereinafter. 
The impact-absorbing profile 2 detachably and form-lockingly secured at the 
cross bearer, has a thick wall of elastic material or of rubber; the wall 
is arranged essentially U-shaped so that legs 12 and a web 13 of the 
profile can be distinguished. 
A large number of transversely extending cross ribs 14 connecting the legs 
12 and the web 13 are arranged on the inside of the U-shaped profile 2, 
which at their open forward edge 14a are constructed corresponding to the 
shape of the support plate 7 and abut against the same and are able to 
support themselves against the same in case of impact. 
Grooves 15 are provided at the ends of the legs 12 on the inside thereof 
which extend transversely to the direction of the legs and correspond to 
the location and shape of the mounting edges 9. In the illustrated 
embodiment, one groove flank is flush with the front edge 14a of the cross 
ribs 14 so that a large-surfaced and uniform support can take place on the 
support plate 7 and on the mounting edge 9. The portion of the leg 12 of 
the U-shaped profile 2 which extends to the rear of the groove 15, forms a 
fastening bead or bulge 16. The side edges 17 of the clamping bar 6 
overlap these beads or bulges 16 with prestress and the beads 16 are 
pressed externally onto the cross bearer 1. In another possible 
embodiment, the side edges 17 may thereby also engage into a longitudinal 
groove disposed transversely to the groove 15 and provided in the bead 16. 
In every case, however, a lifting-out of the leg ends 12 out of the 
mounting edges 9 under impact loads is reliably prevented by the clamping 
bar 6 or the lateral edges 17 thereof. An excessive spreading of the 
U-shaped profile 2 in the vertical direction and therewith a danger of a 
lifting-out thereof out of the mounting edge 9 is also precluded by the 
cross ribs 14. The impact load is absorbed by the mounting edge 
9--compression of the legs 12--and by the support plate 7--compression of 
the cross ribs 14--and is further transmitted onto the cross bearer 1 over 
a large area. 
While I have shown and described only one embodiment in accordance with the 
present invention, it is understood that the same is not limited thereto 
but is susceptible of numerous changes and modifications as known to those 
skilled in the art and I, therefore, do not wish to be limited to the 
details shown and described herein but intend to cover all such changes 
and modifications as are encompassed by the scope of the appended claims.