Body rail for a motor vehicle

Abstract

A vehicle body rail for a motor vehicle, which is constructed of fiber-reinforced plastic and is designed as a vehicle body rail which absorbs energy in the event of a collision of the motor vehicle, includes a wall. The wall is provided with indentations and/or elevations such that, in the event of an application of a predetermined collision threshold load in a longitudinal direction of the vehicle body rail, a failure of the wall by fragmentation takes place in the area of the indentations and/or elevations.

Claims

1. A vehicle body rail for a motor vehicle, which is constructed of fiber-reinforced plastic and is designed as a vehicle body rail which absorbs energy in the event of a collision of the motor vehicle, the vehicle body rail comprising: a wall, which is provided with indentations and elevations such that, in the event of an application of a predetermined collision threshold load along a longitudinal direction of the vehicle body rail, a failure of the wall by fragmentation takes place in the area of the indentations and elevations, wherein the indentations and elevations form longitudinal grooves, and the longitudinal grooves extend along a longitudinal direction of the vehicle body rail.

2. The vehicle body rail according to claim 1, wherein the indentations and elevations are formed in the wall such that a failure of the wall can be controlled in accordance with a predefined force progression, and is controlled between a failure by fragmentation and a failure by peeling over a failure distance of the body rail.

3. The vehicle body rail according to claim 1, wherein the wall has substantially even shape except for the indentations and the elevations.

4. The vehicle body rail according to claim 3, wherein the fiber-reinforced plastic is reinforced by continuous fibers, and wherein the continuous fibers follow a course of the wall with the indentations and elevations that is in conformity with the indentations and elevations.

5. The vehicle body rail according to claim 4, wherein the fibers are arranged in a manner corresponding to the indentations and elevations via a winding process, a braiding processes a pultrusion process or a continuous production method.

6. The vehicle body rail according to claim 5, wherein the indentations and the elevations are grooves or ridges that are formed parallel to the longitudinal direction of the body rail, and wherein the grooves are formed on an exterior side of the wall of the vehicle body rail, and the ridges are formed on an interior side of the wall of the vehicle body rail.

7. The vehicle body rail according to claim 6, wherein the grooves or ridges are formed to be tapering or widening in the longitudinal direction, and wherein a change of geometry of the grooves or ridges is formed corresponding to a desired progression of the failure force.

8. The vehicle body rail according to claim 7, wherein the vehicle body rail is a profiled rail with an open profile or a closed profile with several walls, and the vehicle body rail is a hollow rail with a substantially rectangular cross-section.

9. The vehicle body rail according to claim 8, wherein the indentations and elevations are arranged in wider wall sections.

10. The vehicle body rail according to claim 9, wherein the vehicle body rail is made of carbon-fiber-reinforced plastic.

11. The vehicle body rail according to claim 10, wherein a thickness of the wall is substantially constant in a direction transversely to the longitudinal direction of the vehicle body rail.

12. The vehicle body rail according to claim 11, wherein the vehicle body rail is arranged in a forward load path in the case of a frontal collision of the motor vehicle or in a rearward load path in the case of a rear collision of the motor vehicle, and is directly or indirectly connected with a cross-member of a bumper.

13. The vehicle body rail according to claim 12, wherein, in its longitudinal direction, the vehicle body rail has at least one high-collision-energy absorption section, in which the indentations and elevations are formed in the wall, and has at least one low-collision-energy absorption section, in which no indentations and elevations are formed in the wall.

14. The vehicle body rail according to claim 1, wherein widest regions of the longitudinal grooves are closest a front end of the motor vehicle, along a forward traveling direction thereof, than narrowest regions of the longitudinal grooves.

15. A vehicle body rail for a motor vehicle, which is constructed of fiber-reinforced plastic and is designed as a vehicle body rail which absorbs energy in the event of a collision of the motor vehicle, the vehicle body rail comprising: a wall having indentations and elevations, the wall being structurally configured to undergo failure by fragmentation in the area of the wall where the indentations and elevations are located upon an application of a predetermined collision threshold load along a longitudinal direction of the vehicle body rail, wherein the indentations and elevations form longitudinal grooves along the longitudinal direction of the vehicle body rail.

16. The vehicle body rail according to claim 15, wherein the longitudinal grooves directly overlap one another along a vertical direction of the vehicle body rail and are formed on opposite external surfaces of the vehicle body rail.

17. The vehicle body rail according to claim 16, wherein widest regions of the longitudinal grooves are closest to either a forwardmost end or a rearmost end of the motor vehicle, along a longitudinal direction of the motor vehicle.

18. The vehicle body rail according to claim 16, wherein a first region of the longitudinal grooves is interposed between opposite second regions of the longitudinal grooves along a longitudinal direction of the vehicle body rail, the first region being the widest of any other region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic lateral view and a sectional view of a body rail;

(2) FIG. 2 is a schematic diagram which qualitatively illustrates a progression of force over a time in the event of a failure of the body rail of FIG. 1;

(3) FIG. 3 is a schematic lateral view and a sectional view of a body rail;

(4) FIG. 4 is a schematic diagram which qualitatively illustrates a progression of force over a time in the event of a failure of the body rail of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1 is a schematic lateral view of a body rail 1. As illustrated in a schematic sectional view along Line A-A, the body rail 1 has a substantially rectangular cross-section. At its long sides, the rectangular body rail 1 has two mutually opposite walls 11 and 12. The mutually opposite walls 11 and 12 are connected on the short sides also by mutually opposite walls 13 and 14, the four walls 11, 12, 13, 14 together forming a rectangular profile of the vehicle rail 1. Two grooves 3 respectively, which represent the indentations, are formed in the mutually opposite walls 11 and 12. The grooves 3 are formed particularly on the exterior sides (outer sides) of the walls 11 and 12. The grooves 3 extend parallel to a longitudinal direction of the body rail 1. Elevations or ridges 5, which correspond to the grooves 3, are formed on the interior sides (inner sides) of the walls 11 and 12. The grooves 3 and the elevations 5 are designed to correspond to one another particularly such that a wall thickness of the walls 11 and 12 does not change or is substantially constant. The grooves 3 as well as the elevations 5 have a tapering course and extend from a beginning (on the left in FIG. 1) of the body rail 1 over a defined length along the longitudinal direction of the body rail 1. The groove 3 is the widest at the beginning of the body rail 1 and tapers continuously to its end. The section of the body rail with the grooves 3 and elevations 5 is a high-collision-energy absorption section. In a section of the body rail 1 that follows, e.g., the right-hand section in FIG. 1, no groove or elevation is formed. This section is a low-collision-energy absorption section.

(6) A failure of the body rail 1 during a collision of the motor vehicle will now be explained. The body rail 1 may, for example, be a forward side rail, which frequently is also called an engine mount, in which case a left end of the body rail 1 points in the main traveling direction of the motor vehicle and a right end of the body rail 1 points against a main traveling direction of the motor vehicle. However, the body rail 1 may also be another structurally effective rail in a motor vehicle body which, in the event of a collision of the motor vehicle is stressed along its longitudinal direction. During its failure, such a body rail 1 is used to reduce collision energy and has the purpose of ensuring that a threshold value of a deceleration/acceleration, which acts upon a vehicle occupant, is not exceeded.

(7) If now, as a result of a collision, a collision load acts in the longitudinal direction of the body rail 1, particularly from the direction of the left side in FIG. 1, a failure of the body rail 1 may be induced or triggered at its left end or its forward end with respect to the collision direction, so that a failure is induced at the forward end.

(8) At the forward end, the body rail 1 has particularly wide grooves 3 and elevations 5 corresponding therewith formed in the long side walls 11 and 12. As a result of the grooves 3 and elevations 5, relatively few even sections are formed in the wall 11 or 12 of the rail 1. This results in a relatively small-particle fragmentation of the walls 11 and 12 because the fibers extend along many curvatures. A small-particle fragmentation, in turn, takes place at a relatively high force.

(9) In FIG. 2, a progression of a force during the collision is illustrated qualitatively over time. When the body rail 1 illustrated in FIG. 1 begins to fail at its forward end, this takes place because of the widest point of the grooves 3/elevations 5, in the case of a relatively high force, at an early point in time or a 0 point in time. However, since the grooves 3/elevations 5 become continuously narrower, the even sections will decrease in proportion to the uneven sections, e.g., the grooves and elevations respectively, so that a fragmentation of the walls 11 and 12 will become increasingly coarser. In FIG. 2, this is schematically illustrated by a declining progression of force. When the failure of the body rail 1 now reaches a section in which there are no more grooves and elevations and the walls 11 and 12 extend substantially even, a failure by peeling will thereby be promoted. A failure by peeling occurs at a lower force than a failure by fragmentation. Significantly fewer fibers are broken during a failure by peeling, and the walls 11 and 12 normally bend substantially toward the outsidewhich means that they are deflected up to 180, in which case they tear off at the edges to the upper surface and the lower surface or of the upper wall and the lower wall. Starting from the section of the body rail 1 in which there are no longer any grooves and elevations and the geometry of the body rail 1 no longer changes along a length, the failing therefore takes place at a relatively low force, which is substantially constant.

(10) Naturally, the body rail 1, which is shown in FIG. 1, as well as the progression of force, which is shown in FIG. 2, are illustrated in a somewhat idealized manner, but should illustrate the basic principle of this application in a qualitatively good fashion.

(11) Many other geometries of the body rail are conceivable, in which case, as a result of targeted unevennesses in the body rail, which lead to curvatures in the walls and therefore curvatures of fibers, the failure can be controlled in a targeted manner and, in particular, a failure by fragmentation, or a failure by peeling or a smaller-particle failure or a larger-particle failure can be caused which, in each case, takes place at different force levels.

(12) During the course of the collision, this has the particular advantage that, for example, in the case of a smaller effective mass, during the course of the collision the force level at which a failure takes place, can also be reduced, so that a deceleration/acceleration acting upon a vehicle occupant does not exceed a defined threshold value.

(13) FIG. 3 illustrates another body rail 1. For identical or similar characteristics, the same reference numbers will be used as those in the body rail 1 of FIG. 1. In the following, particularly the differences with respect to the body rail 1 of FIG. 1 will be explained, and an explanation of the commonalities with the body rail 1 of FIG. 1 will be omitted.

(14) As shown in FIG. 3, the body rail 1 has indentations 3 and elevations 5 respectively formed in opposite lateral walls 11 and 12 of a rectangular profile. In FIG. 3, however, the indentations 3 and elevations 5 respectively are formed such that, starting from a forward end of the body rail 1, they widen in a slowly progressing manner, have a constant width over a defined distance and taper in a progressing manner in a section that follows.

(15) A failing of the body rail 1 of FIG. 3 also takes place from the left, thus beginning from the forward end of the body rail 1, in which case the failure at the forward end can be triggered correspondingly. In the event of a collision of the motor vehicle, in which a load acts upon the body rail 1 from the left along a longitudinal direction of the body rail 1, the above-described geometry of the indentations 3/elevations 5 has the effect that a force at which the body rail 1 fails is relatively low at the beginning of the failure, then rises continuously, remains constant at a highest level and then continuously drops again corresponding to the tapering of the groove until the force remains constant again at a low level.

(16) The progression of force is caused in that, when a failure begins at the forward end of the body rail 1, this failure at first takes place with a peeling-open because of the absence of grooves 3 and elevations 5, and then changes into a continuously smaller-part fragmentation which, in turn, at straight sections of the grooves 3 and elevations, reaches a constant level. In the area of the tapering grooves 3 and elevations 5, the fragmentation becomes a continuously larger-part fragmentation until it changes into a failure by peeling.

(17) As illustrated in FIGS. 2 and 4, a progression of force during a failure of the rail can be influenced as desired by adapting the geometry of the rail. In particular, the change of geometry takes place by a change of a relationship between even surfaces and curved surfaces, whereby a type of a failure is controlled. In the case of relatively highly curved surfaces, the corresponding walls of the body rail have the tendency to fail by fragmentation, while, in the case of relatively large even surfaces, it is probable that a failing by peeling will occur. As a result of intermediate stages between these types of failures, desired progressions of force thereby become possible over time without significantly changing an installation space of the rail or increasing a weight of the rail.

(18) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.