Force limiter for a vehicle seat belt and arrangement of a force limiter in a vehicle

Abstract

The invention relates firstly to a force limiter (10) for a vehicle safety belt, comprising a deformation element (12) which can be extended in length (L) in the course of an active force limiting along a main extension direction (H). Secondly, the invention relates to an arrangement of such a force limiter (10) in a vehicle, wherein a first force limiter (10) is fixed at its first end (16) with the fixing means (15) to a vehicle body and at a second end (18) to a belt buckle (14) and / or a second force limiter (10) is fixed at its first end (16) with the fixing means (15) to a vehicle body and at a second end (18) to a belt end point.

Description

[0001] The invention relates to a force limiter for a safety belt of a vehicle according to claim 1 and an arrangement of such a force limiter in a vehicle according to claim 14.

[0002] One function of a force limiter of this type is to reduce load peaks in a vehicle's seatbelt system during a vehicle occupant's forward displacement in the event of a collision. The use of such a force limiter in combination with a belt tensioner is particularly effective, as it eliminates slack, i.e., a loose fit of a seatbelt on a vehicle occupant, before the vehicle occupant is displaced forward. Such a belt tensioner is known, for example, from EP 1 283 138 A1.

[0003] A force limiter of this type is known, for example, from document DE 10 2022 201 664 A1, and its effect is complementary to that of a belt tensioner. Force limiters of this type are largely well-developed and very effective, but there is an incentive to make them even more cost-effective in order to make them available to an even wider audience.

[0004] Furthermore, the subject matter of the preamble of claim 1 is known from the documents DE 298 20 543 U1, DE 298 00 909 U1, DE 20 05 557 A and US 2005 / 0 012 319 A1.

[0005] Against this background, it is an object of the present invention to provide a generic force limiter which represents a more cost-effective solution with an equally good effect.

[0006] This object is achieved by means of the subject matter according to claim 1 and an arrangement according to claim 16. The dependent subclaims form advantageous embodiments.

[0007] The force limiter for a vehicle seat belt comprises a deformation element whose length can be extended along a main direction of extension during active force limitation. The amount of energy acting on the belt webbing or the vehicle occupant during active force limitation due to a vehicle impact – or a similarly strong deceleration – is largely absorbed by the material deformation of the deformation element.

[0008] On the one hand, this can occur when the material of the deformation element itself exhibits this material deformation, as can be the case, for example, with a geometric design as a rod. On the other hand, it is conceivable that the material deformation of the deformation element occurs due to its geometric arrangement, as is the case, for example, with a design with projections, undercuts (e.g., like the coils of a spring), and / or a meandering extension. In the second group, the change in length occurs primarily due to the geometric arrangement or design.

[0009] Compared to the solution in the cited publication, this solution represents a controversial approach that allows for the use of fewer components while maintaining the same excellent force limiting effect. In particular, it makes it possible to manufacture the force limiter according to the invention at a reduced cost.

[0010] Force limiters according to the prior art can comprise extensive assemblies, such as a (force) deflection device for a tension transmission means arranged on a deformation element. A belt buckle or an actuating element can be arranged directly on the tension transmission element. Furthermore, in the active force limitation according to the prior art, the deformation element is usually shortened or compressed along a main extension direction—contrary to the solution according to the invention. In the present invention, however, the deformation element is lengthened or stretched.

[0011] In comparison, according to the invention, the deflection device and / or the tension transmission means can advantageously be eliminated as components, for example, since the deformation element can also be used as a tension transmission element, and no force deflection is required. The deformation element can be directly or indirectly connected to an actuating element, such as a belt buckle, in a force-conducting manner.

[0012] An advantageous embodiment of the invention provides that the deformation element has a fixing means for fixing the deformation element to a vehicle body, which is at the same time an integral component of the deformation element.

[0013] This design advantageously allows for a further reduction in the number of components of the force limiter, resulting in greater cost savings. At the same time, the force limiter's force curve can be implemented more consistently, taking into account unpredictable aging or environmental influences over time, for example, due to material changes in the fixing agent. The quality of the force limiter is thus improved.

[0014] According to a further advantageous embodiment, it is provided that the deformation element has a tensile stress during the active force limitation or that a tensile stress acts on the deformation element.

[0015] As with the two previously described embodiments, the number of components can be reduced, since a direct force connection between the fixation on the vehicle body and the actuating element can be achieved without a force deflection device.

[0016] Another very advantageous embodiment of the invention provides for the deformation element to have unequal dimensions—viewed in cross-section. Identical dimensions include, for example, circular or square shapes. Unequal dimensions deviate from these shapes, for example, by being elliptical or rectangular.

[0017] The advantage of this design is that the respective cross-section has a positive effect on the required force-displacement curve of the force limiter, or the required force-displacement curve can be variably adjusted.

[0018] The same applies to a design of the deformation element – ​​viewed in cross-section – with identical dimensions (e.g., circular or square). A combination of designs with identical and unequal dimensions is conceivable. Specifically, the same dimensions could be configured in a first section of the deformation element, and the unequal dimensions in a second section. The combined design could also be repeated alternately. This has a (further) positive influence on the desired force-displacement curve of the force limiter.

[0019] According to the invention, the deformation element has a helix shape that extends spirally along a longitudinal axis of the deformation element and / or is meander-shaped, wherein the meander-shaped configuration also extends in the main direction of extension along the longitudinal axis. The meander-shaped configuration comprises turns that extend at an angle to one another and an arcuate connecting piece that always connects two turns to one another, for example, with a 180° arc. The main direction of extension is essentially transverse to the turns.

[0020] This embodiment can also have a positive effect on the force-displacement curve to be achieved, or can cause this during active force limitation.

[0021] All previously mentioned embodiments have in common that the deformation element is initially in a shortened form during an inactive force limitation and is only lengthened over the course of the active force limitation.

[0022] In a further embodiment, it can advantageously be provided that the force level of the deformation element is adjustable for active force limitation. This can be implemented, for example, by the deformation element having different cross-sections and / or recesses, which can be manipulated accordingly, in particular to achieve a specific force-displacement curve. In particular, the deformation element can have the different cross-sections and / or recesses in certain sections. Further measures for achieving the adjustable force level include, for example, the (section-by-section) design as a helix and / or meandering shape, or the use of (section-by-section) different cross-sections. A combination of the various designs is therefore entirely possible.

[0023] In all embodiments, the desired result is a deformation element that exhibits a substantially horizontal and / or constant force-displacement curve—when viewed in a force-displacement diagram. This feature is consistent with current legal requirements for modern force limiters, which should meet this curve. Thus, this feature applies to all embodiments in particular in order to comply with the law. Accordingly, the present invention provides a simple and cost-effective implementation in this regard.

[0024] All described embodiments can exhibit or generate torsion or twisting of the deformation element during active force limitation. This occurs particularly at the coupling points of the deformation element, namely at the attachment to the body and at the attachment to the actuating element. This can result in negative effects, such as twisting of the actuating element or unintentional release of the attachment. This would prevent the force limiter from functioning properly.

[0025] To counteract this effect, the deformation element can have an anti-twist device.

[0026] Further, according to the invention, for example, in the helical embodiment, this can be implemented by dividing the deformation element into at least two sections, with the helix of one section extending in the opposite direction to the helix of the other section. With active force limitation, the acting torques are thereby neutralized, similar to the effect in the packaging of a candy.

[0027] Regardless of this, in a further embodiment of the helical design, the helix can have a pitch in a 360° arc around the longitudinal axis that is between 1.0 and 5.0 times the thickness or width of the deformation element. The specified pitch refers to a deactivated state of the force limiter. A 1.0-fold pitch would mean that during a 360° rotation, the upper edge of the lower deformation part and the lower edge of the upper deformation part touch. Accordingly, with higher pitches, the angle of rise is greater.

[0028] The different gradients allow specific force-displacement curves of the deformation element to be achieved in an advantageous manner.

[0029] This advantage can be further improved by having the helix with different gradients in at least two different sections.

[0030] Another embodiment provides for the deformation element of the force limiter to be dimensioned such that the extendable length during active force limitation is in the range of 50 to 200 mm, preferably approximately 90 mm. The specified length optimally adapts to the dimensions of a vehicle occupant positioned on a vehicle seat, who experiences a forward displacement during active force limitation.

[0031] An arrangement of a force limiter according to one of the previously described embodiments in a vehicle provides that a first force limiter is fixed at its first end with the fixing means to a vehicle body and with a second end to a fastening element, in particular a belt buckle, and / or a second force limiter is fixed at its first end with the fixing means to a vehicle body and with a second end to a belt end point, in particular an end fitting.

[0032] The arrangement thus allows the force limiter to act either unilaterally or bilaterally (laterally) on a vehicle seat. The unilateral design achieves asymmetrical damping for the vehicle occupant, whereas the bilateral design acts symmetrically. Depending on the design of the force limiter, it is therefore possible for equal forces to act on the left and right sides of the vehicle occupant's body, thus minimizing the risk of injury.

[0033] Metals, metal alloys and / or plastics can be used as materials for the deformation element.

[0034] The invention is explained in more detail below using several exemplary embodiments with reference to the figures. They show: Fig. 1 a force limiter with a meander-shaped deformation element in a deactivated state according to a first embodiment; Fig. 2 a force limiter with a helical deformation element in deactivated state according to a second embodiment; Fig. 3 a force limiter with a helical deformation element in deactivated state according to a third embodiment; Fig. 4 the item according to the Fig. 3 with active force limitation; Fig. 5 a cross section of the deformation element according to the Fig. 1 and Fig. 3; Fig. 6 a cross section of the deformation element according to the Fig. 2; and Fig. 7 a force-displacement diagram with a drawn force-displacement curve for an active force limitation according to the illustrated embodiments of the Fig. 1 to 3.

[0035] The Fig. 1 shows a force limiter 10 in a first embodiment not according to the invention. It can be seen that it has a deformation element 12 that extends in a meandering shape in a main extension direction H. At a first and a second end 16, 18, the deformation element 12 has a fixing means 15. At the first end 16, the fixing means is provided for fixing to a vehicle body of a vehicle. At the second end 18, the fixing means 15 is provided for fixing to an actuating element 14, in particular a belt buckle or an end fitting. The fixing means 15 are an integral part of the deformation element 12. In this context, an integral part means, in particular, a one-piece design of the components.

[0036] It is also evident that two adjacent turns of the meandering structure are spaced apart by a pitch S. During the active force limitation, the deformation element 12 is deformed, while the pitch S increases. Considered for the entire deformation element 12, a length L is increased along the main extension direction H. The deformation can be elastic and / or plastic.

[0037] The Fig. 2 shows a second embodiment in which the deformation element 12 extends helically along the main extension direction and around the longitudinal axis H. The embodiments as they correspond to the embodiment of the Fig. 1 apply analogously here. In particular, the same fixations are possible with the fixation means 15 at the first and second ends 16, 18. A pitch S of the turns per 360° can run at a steep and / or shallow angle. It is therefore possible for different sections along the main extension direction H to be provided, each of which has a different pitch S implemented.

[0038] The Fig. Fig. 3 shows a third embodiment of a deformation element 12 according to the invention, wherein the statements regarding the fixation of the first and second embodiments are to be applied analogously here as well. According to the invention, it is evident that the deformation element 12 has two different sections A1 and A2. The two sections A1 and A2 differ in the initial extension of the helix, namely once in the direction R1 and once in the direction R2, wherein an anti-twist device 20 is provided by an opposite arrangement of the helix. In the course of the active force limitation - as is also known, for example, from the Fig. 4 - no torques act on the fixing devices 15.

[0039] In contrast to the second embodiment, as shown in the Fig. 2, the deformation element according to the third embodiment ( Fig. 3) a different cross-section, namely one with different dimensions (length and width).

[0040] Accordingly, the first and third embodiments are to be assigned a cross-section, as shown for example in the Fig. 5. The second embodiment ( Fig. 2) the cross section of the deformation element 12 is according to the Fig. 6 to be assigned.

[0041] The different cross-sections of the deformation element 12 lead to different force-displacement curves 110, different deformations and the possibility of implementing a torsion protection 20.

[0042] The third embodiment according to the Fig. 3 can have different gradients S1, S2 of the helix in the sections A1 and A2, whereby modified force-displacement curves 110 can be achieved.

[0043] The Fig. 4 shows the object according to the Fig. 3 in the active force limitation. It can be seen that the length L of the deformation element 12 has increased several times compared to the initial state. In particular, this change in state results from the extension of the slope S1, which in the deactivated state is Fig. 3 can be shortened considerably.

[0044] For all three examples, the force-displacement diagram 100 applies, which is shown in the Fig.7. It can be seen that an almost vertical increase in force (up to approximately 20 kN) occurs in the first millimeters (mm) of the length change of the force limiter 10. Then, an almost horizontal curve can be observed, which extends in the range of approximately 5 mm to 80 mm length change of the deformation element 12. As an alternative embodiment, for example, the almost vertical increase in force in the first millimeters (mm) of the length change of the force limiter 10 can occur in a range between 2 and 8 kN. The values ​​of the force increase in kN stated here are purely examples and are intended to clarify the intended use and dimensioning of the force limiter 10. The person skilled in the art is provided with information by means of this document, whereby alternative force curves can also be achieved, i.e. it is possible to achieve force-displacement curves 110 that deviate from these examples using the measures described. List of reference symbols 10 force limiters 12 Deformation element 14 Actuator / belt buckle 15 Fixatives 16 first end 18 second end 20 Anti-twist device 100 force-displacement diagram 110 Force-displacement curve Section A B Width, diameter C Depth F traction force H Main direction of extension / longitudinal axis L length R direction S gradient

Claims

[1] Force limiter (10) for a safety belt of a vehicle, with a deformation element (12) which can be extended in its length (L) along a main extension direction (H) during an active force limitation characterized by that the deformation element (12) has a shape of a helix which extends spirally along a longitudinal axis (H) and is divided into at least two sections (A), wherein the helix extends in the opposite direction (R) compared to the other section (A). [2] Force limiter (10) according to claim 1, characterized by that the deformation element (12) has a fixing means (15) for fixing the deformation element (12) to a vehicle body and / or to an actuating element (14), which is an integral part of the deformation element (12). [3] Force limiter (10) according to claim 1 or 2, characterized bythat the deformation element (12) has a tensile stress during the active force limitation or that a tensile stress acts on the deformation element (12). [4] Force limiter (10) according to one of claims 1 to 3, characterized by that the deformation element (12) - viewed in a cross-section - has unequal dimensions. [5] Force limiter (10) according to one of claims 1 to 4, characterized by that the deformation element (12) - viewed in a cross-section - is rectangular or round. [6] Force limiter (10) according to one of claims 1 to 5, characterized by that the deformation element (12) is adjustable in its force level for the active force limitation. [7] Force limiter (10) according to one of claims 1 to 6, characterized by that the deformation element (12) - viewed in a force-displacement diagram (100) - has a horizontal and / or constant course of the force-displacement curve (110). [8] Force limiter (10) according to claim 6 or 7, characterized by that the deformation element (12) has different cross-sections and / or recesses. [9] Force limiter (10) according to one of claims 6 to 8, characterized by that the deformation element (12) has different cross-sections and / or recesses in sections. [10] Force limiter (10) according to one of claims 1 to 9, characterized by that the deformation element (12) has an anti-twist device (20). [11] Force limiter (10) according to one of claims 1 to 10, characterized by that the helix has a pitch (S) in an arc section of 360° around the longitudinal axis (H) which is between 1.2 and 5.0 times a width (B) - based on the inactive state of the force limiter (10) - of the deformation element (12). [12] Force limiter (10) according to one of claims 1 to 11, characterized bythat the helix has at least two different sections with different pitches (S). [13] Force limiter (10) according to one of claims 1 to 12, characterized by that the extendable length (L) of the deformation element (12) during active force limitation is in the range of 50 to 200 mm. [14] Arrangement of a force limiter (10) according to one of claims 1 to 13 in a vehicle, wherein a first force limiter (10) is fixed at its first end (16) with a fixing means (15) to a vehicle body and with a second end (18) to a belt buckle (14) and / or a second force limiter (10) is fixed at its first end (16) with a fixing means (15) to a vehicle body and with a second end (18) to a belt end point.

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