WO2009054796A2

WO2009054796A2 - Stiffening element for a vehicle body description

Info

Publication number: WO2009054796A2
Application number: PCT/SE2008/051199
Authority: WO
Inventors: Jochen Ewert; Rüdiger Lang
Original assignee: Autoliv Development Ab
Priority date: 2007-10-27
Filing date: 2008-10-23
Publication date: 2009-04-30
Also published as: DE112008002875T5; DE112008002875B4; WO2009054796A3; DE102007051464B3

Abstract

A stiffening element (13) for the vehicle body of a motor vehicle, which stiffening element (13) is arranged in the vehicle body such that the stiffening element (13) is flexurally loaded during an accident, wherein the end regions (16) of the elongated stiffening element (13) are interconnected by way of a traction means (15) that extends in longitudinal direction of the stiffening element (13), whereby the traction means (15), in the case of the device being triggered, is tensioned by way of a triggerable tensioning device that generates a tension force acting at a right angle to the stiffening element (13) such that the bending forces that during an impact act on the stiffening element (13) cause compressive strain that acts in longitudinal direction of the stiffening element (13).

Description

STIFFENING ELEMENT FOR A VEHICLE BODY

DESCRIPTION

The invention relates to a stiffening element for the vehicle body of a motor vehicle, which stiffening element is arranged in the vehicle body such that in an accident the stiffening element is subjected to flexural loads, wherein the end regions of the elongated stiffening element are interconnected by way of a traction means that extends in longitudinal direction of the stiffening element.

Such a stiffening element in the form of a hollow profile is described in DE 10 2006 Oil 808 Al. In the interior of the hollow profile a pre-tensioned cable is arranged, which at least in sections extends along an arced shape wherein the two extremities of said cables are affixed to the hollow profile. In this arrangement the pre-tension generated in the hollow profile by the tensioned cable is intended, during an impact on the stiffening element, to counteract the expected forces that act on the hollow profile, in that the occurring bending load of the hollow profile is converted to a traction load.

However, the stiffening element designed in this manner is associated with a disadvantage in that manufacture is expensive because the traction means arranged in the stiffening element has to be provided with the required pre-tension before the stiffening element is further installed in a vehicle body.

It is thus the object of the invention to design a stiffening element with the features mentioned in the introduction so that it is easier to manufacture and also easier to install in a vehicle body. This object, including advantageous embodiments and improvements of the invention, is met as stated in the content of the claims that follow this description.

In detail, the invention provides for the traction means, in the case of the device being triggered, to be tensioned by way of a triggerable tensioning device that generates a tension force acting at a right angle to the stiffening element, such that the bending forces that during an impact act on the stiffening element cause compressive strain that acts in longitudinal direction of the stiffening element.

The invention is associated with an advantage in that tension of the traction means, which tension is required for conversion of bending forces acting on the stiffening element during an impact, is generated only during an impending or occurring impact, namely by way of a correspondingly triggerable tensioning device that generates a tension force that results in tensioning the traction means. This tension force, which is aligned so as to be perpendicular to the stiffening element, results in the best-possible utilisation of the movement path provided by means of the tensioning device. To the extent that the tensioning device provided for this requires a drive, the drive forces that are to be generated in each case are comparatively modest. It can be accepted that activation of the tensioning device that acts on the traction means results in an increased requirement for space for the stiffening element, and in this way there is a possibility of, for example, door installations being destroyed, since after the stiffening element has been subjected to a load incident the corresponding body component will have to be replaced anyway.

In a first embodiment of the invention a single-part profiled stiffening element is provided, wherein according to corresponding exemplary embodiments the profile of the stiffening element can be a U-profile, a C-profile or a double C-profile, wherein the stiffening element is preferably integrated in the vehicle body such that the closed side of the profile faces the direction of the possible impact. Other suitable profile forms also fall within the scope of the invention.

As far as the design of the tensioning device for a stiffening element with such a profile is concerned, a first exemplary embodiment of the invention provides for the tensioning device to comprise at least one lever that is supported by the stiffening element and that in the case of the device being triggered spreads the traction means apart from the stiffening element. To the extent that the traction element is tensioned by the correspondingly provided lever, subsequently the bending forces, which during lateral impact act from the outside on the stiffening element, cause tensile strain in the traction element, which tensile strain due to the traction element being coupled to the ends of the stiffening element is converted to corresponding compressive strain in the stiffening element. Consequently the flexural strength of a stiffening element subjected to loads in this way is considerably greater than the flexural strength of a profile alone, which profile forms the stiffening element.

It can be provided for a plural number of levers to be arranged along the length of the stiffening element.

Individually, in order to form the lever as a tensioning device for the traction means, it can be provided for one end of the lever to be rotatably held on the stiffening element, while the other end of said lever acts on the traction element, wherein, furthermore, it can be provided for the lever in its home position to cause a slight excursion of the traction means that connects the ends of the stiffening element from its stretched position. Thus, before the tensioning device is triggered, the lever is within the contour of the stiffening element, wherein, however, as a result of the already set slight excursion of the traction means from its stretched position the process of spreading apart is facilitated by the lever.

According to a first exemplary embodiment of the invention, it can be provided for the end of the lever, which end is held on the stiffening element, to be arranged so as to be slidable in longitudinal direction of the stiffening element by means of an associated drive. As an alternative, it can be provided for the traction means to be brought under tensile strain by way of a take-up device that acts on said traction means, with said take-up device being operated by means of a drive. Yet another alternative can provide for the lever to be designed as an articulated lever with an interposed joint, which articulated lever can be brought to its stretched position by means of a drive that acts on its joint.

A further embodiment of the invention provides for the stiffening element to be designed in two parts comprising two profile components that are movable relative to each other by means of the tensioning device, wherein the ends of the traction means that is arranged between the profile components are connected to one profile component, and a section of the traction means, which section is situated between the ends of the traction means, is connected to the other profile component. This embodiment is associated with an advantage in that a stiffening element that is designed in two parts, preferably with overlapping profile components, provides greater robustness in the face of forces that act unevenly along its length than is the case with a single-part stiffening element. Furthermore, this embodiment makes it possible to provide the required tension force by way of the movement of at least one of the profile components, in particular to provide the tension force directly also to the traction means. This increases the degree of freedom in the design or in the arrangement of the tensioning device. In order to convert the tension force to the tension means by moving at least one profile component, the two ends of the traction means are held on one profile component, while the section situated between the ends is connected to the other profile component.

According to exemplary embodiments of the invention, one profile component is a rigid profile component that is connected to the vehicle body, while the other profile component is arranged so as to be movable, or both profile components are arranged so as to be movable relative to each other.

Expediently, the ends of the traction means are attached to the profile component that faces towards the outside of the vehicle body, while the middle part of the traction means, which middle part is situated between the ends, is attached to the profile component that faces towards the inside of the vehicle body. In this arrangement the profile component that faces the inside of the vehicle body is preferably movable towards the interior of the vehicle.

In a two-part profile component the two profile components together can form a closed stiffening element. As an alternative it can be provided for one profile component to be a plate-shaped element, while the profile component that is movable relative to the plate-shaped element comprises a profiled structure. To the extent that a plate-shaped profile component provides better stability, this plate- shaped profile component can expediently be arranged in the region of the outside of the vehicle body.

As far as the design of the tensioning device equipped for a two-part profile component is concerned, a first embodiment of the invention can provide for the tensioning device to comprise at least one telescopic cylinder that is arranged between the two profile components and that during activation presses the profile components apart. In this arrangement the telescopic cylinder, or if required several telescopic cylinders, can be arranged in the stiffening element such that before activation they contribute to protecting the stiffening element from collapsing or buckling. Thus, to the extent that the telescopic cylinders that are arranged between the two profile components ensure additional stiffening of the two-part stiffening element, this is associated with an advantage in that the profile components that form the stiffening element can themselves be designed for example with a reduced wall thickness, which is associated with a reduction in weight.

It can be provided for the telescopic cylinders to be pyrotechnically drivable . Any other suitable drive type is also covered by the scope of the invention.

According to an alternative embodiment of the invention, the tensioning device can comprise a gas generator that generates gas that is led into the interior of the stiffening element. The gas generated by the gas generator is led into the stiffening element and causes a corresponding relative movement of at least one profile component relative to the other profile component. To this effect the stiffening element can be designed so as to be gas-proof. However, it may also be adequate if the two profile components are designed so as to be open, for example comprising an already mentioned plate-shaped profile component, provided the gas stream fed to the movable profile component is sufficiently strong to move the profile component.

Yet another alternative embodiment can provide for the tensioning device to comprise a traction device that acts on the outside of the at least one movable profile component. This is associated with an advantage in that there is no associated restriction in the manufacture of the vehicle, for example during the application of an anticorrosive agent to the respective vehicle body parts, including a provided stiffening element, because the tension device that is to be affixed outside the stiffening element can be installed after this.

In order to trigger the tensioning device, according to a first exemplary embodiment of the invention, a pre-crash sensor is installed on the motor vehicle, which pre-crash sensor emits a triggering signal, wherein the movement of the profile components relative to each other and wherein the drive for the tensioning device are designed so as to be reversible, wherein the drive for the tensioning device can be a pneumatic or an electric drive. Both drives support a reversible function, wherein it must also be ensured that the movement of the movable profile component is designed so as to be reversible. Corresponding pre-crash sensors are presently already installed in motor vehicles for the control of components of seatbelt- and/or airbag devices .

As an alternative, or in addition, according to an exemplary embodiment of the invention, for the purpose of triggering the tensioning device, sensors are provided which detect any bending of the stiffening element, which bending starts during a crash. Such a design provides the option of inserting in the vehicle body a design module that is independent per se, with a correspondingly designed stiffening element and associated sensors.

To the extent that an exemplary embodiment of the invention provides for the stiffening element to be a metal stiffening element and therefore to comprise a corresponding metal profile, the invention comprises, however, any other suitable materials that are available for forming the stiffening element.

The drive for the tensioning device, in particular for the movement of the lever or the function of the take-up device for the traction means, which movement is required in the first embodiment of the invention, can be designed as a pyrotechnic drive, or in another embodiment of the invention it can be designed as a triggerable pre-tensioned spring-type cylinder. The scope of the invention also includes further suitable drive types.

As shown in generic DE 10 2006 Oil 808 Al, an advantageous application of the stiffening element according to the invention consists of the installation of this stiffening element in a vehicle side door of the motor vehicle because at this position the risk of a lateral impact is greatest, and lateral bending forces that act on this position are to be absorbed.

The drawing shows exemplary embodiments of the invention that are described below. The following are shown:

Fig. 1 a lateral view of a vehicle door with a stiffening element installed therein;

Fig. 2 a section of the reinforcement element according to line II - II in Figure 1 ;

Fig. 3 a lateral view of the reinforcement element with an associated traction element prior to triggering the tensioning device for the traction element;

Fig. 4 the object shown in Figure 3 after the triggering of the tensioning device; Fig. 5 another embodiment of the object of Figure 4 ;

Fig. 6 a section view of the stiffening element according to Figure 3 or 4 with a lever effect;

Fig. 7 another embodiment of the object of Figure 6;

Fig. 8 a further modified embodiment of the object of Figure 6 or 7.

Fig. 9 a diagrammatic view, prior to activation of the tensioning device, of a stiffening element comprising two profile components with traction means and tensioning device;

Fig. 10 an individual view of the stiffening element according to Figure 9 prior to triggering the tensioning device;

Fig. 11 the object of Figure 10 after displacement of the movable profile component;

Fig. 12 the object of Figure 9 after activation of the tensioning device and tensioning of the traction means;

Fig. 13 a view, according to that of Figure 9, of another embodiment of the stiffening element comprising two profile components;

Fig. 14 an individual view of the stiffening element according to Figure 13;

Fig. 15 the object of Figure 14 after displacement of the movable profile component; Fig. 16 a further embodiment of the stiffening element according to Figure 13.

As first of all shown in Figures 1 and 2, a stiffening element 13 can be installed in the body region 12 of a side door 10 of a motor vehicle, below the side window 11 installed therein. Expediently, the stiffening element 13 comprises a double C-profile 14, whose closed sides face towards the outside so that in the case of an accident the impact occurs on the closed side of the profile 14 of the stiffening element 13.

As is further shown in Figure 3, the end regions 16 of the stiffening element 13 are interconnected by way of a traction means 15, which in a preferred manner can be a metal wire. To this purpose, too, all the suitable materials for providing a corresponding traction means can be used. One end 19 of a lever 17 engages the traction means 15, wherein the other end 18 of the lever 17 is rotatably coupled to the stiffening element 13, such that by means of a drive (not further shown) , which in the case of the device being triggered becomes active, the lever 17 can be brought to a position in which the lever 17 spreads the traction means 15 away from the stiffening element 13. In order to facilitate the corresponding excursion of the traction means 15, the lever 17 in its home position is arranged within the profile 14 of the stiffening element 13 such that a slight excursion of the traction means 15 that connects the end regions 16 of the stiffening element 13 from its stretched position is brought about.

If, as shown in Figure 4, as a result of the lever 17 swinging out, and as a result of the associated spreading apart of the traction means 15 away from the stiffening element 13, the traction means 15 is subjected to corresponding tensile strain, then in an accident the forces F that act from the outside on the side door 10 and thus on the stiffening element 13 cause tensile strain in the traction means 15, which tensile strain, due to the ends of the traction means 15 being affixed to the outer end regions 16 of the stiffening element, is converted to compressive strain in the stiffening element 13, which compressive strain acts in longitudinal direction of the stiffening element 13 so that as a result of this the flexural strength of the stiffening element 13 is improved. To the extent that, due to the bending forces F that occur in each case, local bending stress occurs in the stiffening element 13, this bending stress is overall significantly reduced when compared to that in a non-reinforced stiffening element.

The exemplary embodiment of the invention as shown in Figure 5 shows the arrangement of two levers 17 for spreading the traction means 15 apart from the stiffening element 13.

Finally, Figures 6 to 8 show exemplary embodiments as to how the excursion of the lever 17 from its home position shown in Figure 3 can be accomplished. For example, Figure 6 diagrammatically shows that the end 18 of the lever 17, which end 18 is held on the stiffening element 13, is slidably arranged in longitudinal direction of the stiffening element 13 by means of an associated drive (not separately shown in the diagram but merely indicated by the arrow 22 as far as its effect is concerned) so that the lever 17 can be moved into its bracing position.

In the exemplary embodiment shown in Figure 7 the lever is an articulated lever comprising an articulated lever joint 20 so that the effect of a drive (not further shown), which effect is indicated by the arrow 22, is directed onto the articulated lever joint 20 and in this way braces the lever 17. As indicated in Figure 8, one end of the traction means 15 can also lead to a take-up device (not shown) which takes up the traction means 15 in the direction of the arrow 22 and in this way causes an excursion of the lever 17.

In the exemplary embodiments shown in Figures 9 to 16 the stiffening element 13 comprises two profile components 30 and 31, of which at least one profile component is movable relative to the other profile component so that its movement can be used for tensioning the traction means 15.

As shown in this context in Figures 9 and 12 on the one hand, and in Figures 11 and 12 on the other hand, the two profile components 30 and 31 form a stiffening element 13 that is closed in any position of the profile components 30, 31. The fixed profile component 30 is preferably arranged in the vehicle body so that it faces towards the outside of the vehicle, while the movable profile component 31 is movable towards the interior of the vehicle. The traction means 15 and the tensioning device that comprises two telescopic cylinders 32 are arranged in the interior of the stiffening element 13. The extremities 33 of the traction means 15 are attached to the extremities of the fixed profile component 30, while the middle section 34 of the traction means, which middle section 34 is situated between the extremities 33, is attached to the movable profile component 31. If during a crash a force acts in the direction of load according to arrow 35 on the stiffening element 13, then the telescopic cylinders 32, due to their triggering, displace the movable profile component 31 away from the fixed profile component 30; in this process the traction means 15 is tensioned such that the bending forces that act on the stiffening element in the direction of the arrow 35 are converted to compressive strain that acts in longitudinal direction of the stiffening element 13. Figures 13 to 15 show another exemplary embodiment of the invention, wherein the fixed profile component 30 is shaped as a plate, and the movable profile component 31 does not extend over the entire width of the fixed plate 30 but only over the section situated between the telescopic cylinders 32. Such an extent of the movable profile component 31 is adequate to provide the tension of the traction means 15 as described in the context of Figures 9 and 12. Advantageously this results in weight savings.

In the exemplary embodiment shown in Figure 16, the movable profile part is reduced to two sleeves 36 connected to the traction means 15, which sleeves 36 have been pushed over the telescopic cylinders 32, and in the case of triggering are impinged on by said telescopic cylinders 32. Such a reduced design is already sufficient to exert the required tension on the traction means 15.

It is understood that a return stop (not shown in detail) should be provided so that when under load the movable profile component 31 is prevented from returning to its home position.

By installing the stiffening element 13, stiffening of the vehicle body, in particular of the door regions, is achieved already without the application of separate tension force. A certain pre-tension of the traction means can be applied already during installation of the stiffening element. As an alternative, it can be provided for the traction means to be connected to the door opening mechanism such that the traction means is subjected to a degree of pre-tension when the door is closed. This pretension is independent of the effect, provided according to the invention, of the tensioning device.

The characteristics of the object of these documents, which characteristics have been disclosed in the above description, in the claims, in the abstract and in the drawing can be significant, both individually and in any desired combination, to the realisation of the invention in its various embodiments.

Claims

1. A stiffening element (13) for the vehicle body of a motor vehicle, which stiffening element (13) is arranged in the vehicle body such that the stiffening element (13) is flexurally loaded during an accident, wherein the end regions (16) of the elongated stiffening element (13) are interconnected by way of a traction means (15) that extends in longitudinal direction of the stiffening element (13), characterised in that the traction means (15), in the case of the device being triggered, is tensioned by way of a triggerable tensioning device that generates a tension force acting at a right angle to the stiffening element (13) such that the bending forces that during an impact act on the stiffening element (13) cause compressive strain that acts in longitudinal direction of the stiffening element (13) .

2. The stiffening element according to claim 1, characterised in that a single-part profiled stiffening element (13) is provided.

3. The stiffening element according to claim 2, characterised in that the profile (14) of the stiffening element (13) is a U-profile.

4. The stiffening element according to claim 2, characterised in that the profile (14) of the stiffening element (13) is a C-profile.

5. The stiffening element according to claim 2, characterised in that the profile (14) of the stiffening element (13) is a double C-profile.

6. The stiffening element according to any one of claims 3 to 5, characterised in that the closed side of the profile (14) faces the direction of impact.

7. The stiffening element according to any one of claims 1 to 6, characterised in that the tensioning device comprises at least one lever (17) that is supported by the stiffening element (13) and that in the case of the device being triggered spreads the traction means (15) apart from the stiffening element (13) .

8. The stiffening element according to claim 7, characterised in that a plural number of levers (17) are arranged along the length of the stiffening element (13) .

9. The stiffening element according to claim 7 or 8, characterised in that one end (18) of the lever (17) is rotatably held on the stiffening element (13), while the other end (19) of said lever (17) acts on the traction element (15) .

10. The stiffening element according to claim 9, characterised in that the lever (17) in its home position causes a slight excursion of the traction means (15) that connects the ends of the stiffening element (13) from its stretched position.

11. The stiffening element according to any one of claims 7 to 10, characterised in that the end (18) of the lever (17), which end (18) is held on the stiffening element (13), is arranged so as to be slidable in longitudinal direction of the stiffening element (13) by means of an associated drive.

12. The stiffening element according to any one of claims 7 to 10, characterised in that the traction means (15) can be brought under tensile strain by way of a take- up device that acts on said traction means (15), with said take-up device being operated by means of a drive .

13. The stiffening element according to any one of claims 7 to 10, characterised in that the lever (17) is designed as an articulated lever with an interposed joint (20), which articulated lever can be brought to its stretched position by means of a drive that acts on its j oint (20) .

14. The stiffening element according to claim 1, characterised in that the stiffening element (13) is designed in two parts comprising two profile components (30, 31) that are movable relative to each other by means of the tensioning device, wherein the ends (33) of the traction means (15) that is arranged between the profile components (30, 31) are connected to one profile component (30), and a section (34) of the traction means (15), which section (34) is situated between the ends (33) of the traction means (15), is connected to the other profile component (31) .

15. The stiffening element according to claim 14, characterised in that one profile component (30) is a rigid profile component that is connected to the vehicle body, while the other profile component (31) is arranged so as to be movable.

16. The stiffening element according to claim 14, characterised in that both profile components (30, 31) are arranged so as to be movable relative to each other .

17. The stiffening element according to claim 15 or 16, characterised in that the ends (33) of the traction means (15) are attached to the profile component (30) that faces towards the outside of the vehicle body, while the middle part (34) of the traction means (15), which middle part is situated between the ends (33) , is attached to the profile component (31) that faces towards the inside of the vehicle body.

18. The stiffening element according to any one of claims 14 to 17, characterised in that the two profile components (30, 31) together form a closed stiffening element (13) .

19. The stiffening element according to any one of claims 14 to 17, characterised in that one profile component (30) is a plate-shaped element, while the profile component (31) that is movable relative to the plate- shaped element (30) comprises a profiled structure.

20. The stiffening element according to any one of claims 14 to 19, characterised in that the tensioning device comprises at least one telescopic cylinder (32) that is arranged between the two profile components (30, 31) and that during activation presses the profile components (30, 31) apart.

21. The stiffening element according to claim 20, characterised in that the telescopic cylinders (32) are arranged in the stiffening element (13) such that before activation they contribute to protecting the stiffening element (13) from collapsing or buckling.

22. The stiffening element according to claim 20 or 21, characterised in that the telescopic cylinders (32) are pyrotechnically drivable.

23. The stiffening element according to any one of claims 14 to 19, characterised in that the tensioning device comprises a gas generator that generates gas that is led into the interior of the stiffening element (13) .

24. The stiffening element according to claim 23, characterised in that the stiffening element (13) is designed so as to be gas-proof.

25. The stiffening element according to any one of claims 14 to 19, characterised in that the tensioning device comprises a traction device that acts on the outside of the at least one movable profile component (30, 31) .

26. The stiffening element according to any one of claims 14 to 25, characterised in that a return stop is provided which prevents any return movement of the movable profile components (31) .

27. The stiffening element according to any one of claims 1 to 26 which is designed as a stiffening element (13) made of metal.

28. The stiffening element according to any one of claims 14 to 27, characterised in that for triggering the tensioning device a pre-crash sensor is installed on the motor vehicle, which pre-crash sensor emits a triggering signal, wherein the movement of the profile components (30, 31) relative to each other and wherein the drive for the tensioning device are designed so as to be reversible.

29. The stiffening element according to claim 28, characterised in that the drive for the tensioning device is a pneumatic drive.

30. The stiffening element according to claim 28, characterised in that the drive for the tensioning device is an electric drive.

31. The stiffening element according to any one of claims 1 to 30, characterised in that crash sensors that detect an impact are arranged in order to trigger the tensioning device.

32. The stiffening element according to any one of claims 1 to 31, characterised in that sensors are provided that, in order to trigger the tensioning device, during an impact sense commencement of deflection of the stiffening element (13) .

33. The stiffening element according to claim 31 or 32, characterised in that the drive of the tensioning device is designed as a pyrotechnic drive.

34. The stiffening element according to claim 31 or 32, characterised in that the drive of the tensioning device is designed as a triggerable pre-tensioned spring-type cylinder.

35. The use of a stiffening element (13), according to any one of claims 1 to 34, for installation in a side door (10) of a motor vehicle.