Land vehicles: bodies and tops – Bodies – Structural detail
Reexamination Certificate
2002-12-02
2004-12-14
Coletta, Lori L. (Department: 3612)
Land vehicles: bodies and tops
Bodies
Structural detail
C428S036100
Reexamination Certificate
active
06830286
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fiber composite crash structure for a motor vehicle longitudinal member and the like, and more particularly, to a fiber composite produced at least partially from fiber composite material.
Crash structures, deformation elements and energy absorbers are used in vehicle and aircraft construction and in train and helicopter engineering in diverse structural forms and at different points in order to increase the safety. These energy-absorbing components consist, for example, of steel or aluminum sheet or of aluminum extruded profiles. Moreover, fiber composite materials have increasingly been used recently, primarily owing to the weight-saving possibility which is associated therewith.
In motor vehicles, deformation elements having a tubular construction have proven successful in particular in the front and rear regions. A tubular structure of this type is disclosed, for example, in DE 30 49 425 A1. In this case, the crash protective component, which is designed as an open hollow body, has a circumferential surface in the form of netting made of a fiber composite strand for the irreversible absorption of energy in the event of pressure loads in the longitudinal direction. At small pressure loads in the longitudinal direction of the tube, the tube is used for an elastic, reversible support and, at relatively large loads, irreversibly absorbs energy under permanent deformation.
Furthermore, DE 38 33 048 A1 describes a bumper for motor vehicles, which has conically arranged impact tubes made of at least one fiber composite material. The impact tubes, which are arranged conically with respect to one another at a radial distance, are arranged in such a manner that their longitudinal axis extends at least approximately in the longitudinal direction of the vehicle, and therefore in the direction of travel, with the fibers being aligned at least essentially in the longitudinal direction of the tube. Glass fibers, carbon fibers or aramide fibers are used as the fibers.
In addition, DE 43 17 738 A1 discloses an energy absorber which is of cylindrical design and is composed of fiber-reinforced composite material, in which the fiber is wound at least in a circumferential direction of the body. Furthermore, the thickness of the energy absorber, which is of hollow-shaped design, is designed such that it increases gradually in at least two steps in the axial direction.
Furthermore, EP 0 683 072 B1 describes a further, hollow-shaped impact absorber which has the shape of a stepped pyramid or its circumferential surfaces are of terrace-shape design. The energy absorption takes place here predominantly by way of successive shearing processes. The material of the impact absorber consists of fiber material which has been compressed in a dimensionally stable manner.
The known arrangements largely have the disadvantage, however, that a high energy absorption capacity is possible only at a 0 degree impact. If, in contrast, the impact acts at an angle with respect to the longitudinal direction of the absorber element, then a uniform failure behavior does not occur.
It is also disadvantageous that known arrangements only have a low structural integrity. That is, the structure splits into large broken fragments during absorption of the impact energy. Broken fragments of this type constitute, however, a high injury risk and are therefore undesirable.
Furthermore, the crash behavior of the known structures can be calculated only imprecisely, and a high outlay on experimentation is required in order to predict that behavior.
In addition, in many components made of fiber composite material, the production is associated with a high proportion of manual labor, since 3D structures have to be manufactured from sheet-like semifinished fiber composite products. This entails, as a rule, not only a large amount of cutting of the sheet-like semifinished product, but also results in slow and therefore expensive manufacturing.
SUMMARY OF THE INVENTION
The present invention is based on the object of providing a fiber composite crash structure with reproducible crash behavior and optimum structure integrity which, in addition, can be produced cost-effectively.
According to a first embodiment, the object has been achieved by a fiber composite crash structure which has a hollow body produced entirely or partially from fiber composite material. The structure is distinguished according to the invention in that, within the hollow body, a web element is arranged running essentially in the longitudinal direction thereof. The web element is connected to the hollow body essentially in the contact region of web element and hollow body in such a manner that the structure is reinforced by reinforcing elements.
In this embodiment, the hollow body has any desired cross section. It is expedient, however, for the cross section to have an oblong, oval, elliptical, circular or polygonal shape.
A second embodiment of the fiber composite crash structure according to the invention, in which the web element can be omitted, is distinguished in that the hollow body has a circular cross section. Reinforcing elements are introduced into the hollow body wall in order to reinforce the structure.
In addition to the weight reduction, the crash structure according to the invention made of fiber composite material has the advantage of a high specific energy absorption. Even in the case of an oblique impact, the component has high structural integrity and optimum crash behavior. In addition, the absorption behavior can be readily predicted and adapted in a simple manner to desired requirements.
The reinforcing elements are advantageously arranged running essentially in the thickness direction of the hollow body wall. Owing to the orientation of the reinforcing elements, the shock acting on the structure is optimally absorbed and, in particular, the absorption of energy in the case of an oblique impact is substantially improved. In addition, a structure reinforced in such a manner has a better structural integrity. As a result, in the event of a crash, spitting off or spitting up of broken fragments is avoided.
Furthermore, it is expedient to arrange the reinforcing elements in a manner such that they run entirely or in sections in the circumferential direction of the hollow body and along the longitudinal direction thereof.
It is particularly advantageous that the distance between the reinforcing elements both in the circumferential direction of the hollow body and in the longitudinal direction thereof can be set in a variable manner in order to adapt the energy absorption capability of the structure. That is, the absorption behavior can be adapted in a simple manner, by varying the density of the reinforcing elements to a desired force/distance profile. It is advantageous in this respect, since in contrast to known structures, no new design, and therefore also no new tools for producing the structure, are required when adapting the absorption behavior. This constitutes an extremely effective form of adaptation saving on both costs and time.
The reinforcing elements are expediently sewn into the hollow body wall by tufting, and the web element and the hollow body are sewn to each other essentially in the contact region by tufting. The sewing process has the advantage of easy handling capability. In addition, it can easily be integrated in automated production sequences. Thereby, at least partially automated manufacturing is possible, so that shorter manufacturing times and lower outlay on personnel are required, which results in a significant cost reductions.
The reinforcing elements are expediently sewing threads comprising glass and aramide fibers, the use of glass fibers being more cost-effective.
Moreover, it is advantageous that the hollow body has a conical shape in the longitudinal direction and has a variable wall thickness which is of step-shaped design in the longitudinal direction. As an alternative, the hollow body can have a wall thickness continuously increasing in the longitudi
Bechtold Michael
Drechsler Klaus
Maidl Franz
Moeltgen Bruno
Strachauer Frank
Coletta Lori L.
Crowell & Moring LLP
Daimler-Chrysler AG
LandOfFree
Fiber composite crash structure does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fiber composite crash structure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fiber composite crash structure will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3283736