Force limiter

Abstract

The invention relates to a force limiter (1) for a seat belt of a seat belt device of a motor vehicle, comprising: a fitting part (5); -deforming the tube (2); a tension transmitting element (3); and-a displacement part (4) which is connected to the tension transmission element (3) in a tensile manner and which is arranged in or on the deformation tube (2), the deformation tube (2) having a linear portion (21), the displacement part (4) being held in or at an open end (25) of the linear portion, wherein the deformation tube (2) has a deflection portion (22), which is integrally formed with the linear portion (21), in which deflection portion the tension transmission element (3) deflects.

Description

[0001] The present invention relates to a force limiter having the features of the preamble of claim 1.

[0002] Seat belt devices are generally used to restrain vehicle occupants in the event of an accident. For this purpose, the seat belt device has a seat belt that can be wound at a first end around a seat belt spool of a seat belt retractor, which is rotatably mounted in a frame that can be fixed to the vehicle. To form a two-point seat belt, the seat belt can be provided with a tongue at its second end, which can be locked in a buckle fixed to the vehicle. In addition, to implement a three-point seat belt, the seat belt can be fastened at its second end by means of an end fitting on the same side of the vehicle seat as the seat belt retractor, wherein a movable tongue is provided on the seat belt, which can be locked in a buckle fastened on the other side of the vehicle seat in order to divide the seat belt into a three-point geometry.

[0003] The seat belt spool in the seat belt retractor is pre-tensioned in the winding direction by a main spring supported on the frame, so that the seat belt automatically winds up after the tongue is unlocked. In addition, a locking device with an associated sensor device is provided, which locks the seat belt spool against further rotation in the seat belt extension direction if a predetermined value of the seat belt webbing extension acceleration and / or vehicle deceleration is exceeded. This means that if the seat belt spool is locked, the occupant is restrained by the seat belt and protected from impacts with the vehicle's internal structure.

[0004] In addition, modern vehicles are also equipped with airbags, which can be arranged at various points on the vehicle structure and inflated in the event of an accident to cover the vehicle structure. The occupant is restrained by the combination of the seat belt device and the provided airbags.

[0005] Since the occupant is additionally protected from impacts with the vehicle structure by the inflated airbag, it can be proposed to provide an additional force limiter in the seat belt device, which allows a force-limited extension of the seat belt webbing when the seat belt spool is locked. The force limiter can be assigned to the buckle, the end fitting, the deflection device, the seat belt retractor or the fastener of the seat belt spool.

[0006] A force limiter is known from document DE 10 2017 101 807 A1, which is arranged on an end fitting or a buckle and includes a straight deformation tube having a displacement part disposed therein, wherein the displacement part is connected to a tensile force transmission part in the form of a cable, which in turn is connected to a belt transmission part in the form of a buckle or a cable loop. Thus, the seat belt is directly or indirectly connected to the tensile force transmission part via the belt transmission part and to the displacement part via the tensile force transmission part.

[0007] In the case where the plastic deformation limit of the deformation tube is exceeded by the tensile force applied to the displacement part, the displacement part is pulled through the deformation tube under the plastic deformation of the deformation tube, and thus a force-limited extension of the seat belt can be achieved even when the seat belt reel is locked.

[0008] The deformation tube is formed by a straight tube that is fastened to the fitting, and the tensile force transmission part is further deflected at the fitting. In addition to deflecting the tensile force transmission part, the fitting is also used to fasten the force limiter to the vehicle structure. This means that the fastening point of the deformation tube to the fitting is the interface through which the tensile force transmission part must pass. To ensure the guiding of the tensile force transmission part in the region of the interface, an additional connecting element is provided through which the tensile force transmission part extends. The connecting element is supported on the assembly part and is also used to fasten the deformation tube to the assembly part.

[0009] Against this background, the object of the present invention is to provide a cost-effective force limiter that should have a simplified structure with a simplified guide for the tensile force transmission element.

[0010] According to the basic idea of the present invention, it is proposed that the deformation tube has a deflection part integrally formed with the linear part, and the tensile force transmission element is deflected in the deflection part.

[0011] The advantage of the proposed solution is that, in addition to the deflection of the tensile force transmission element, the deformation tube is used, so that the deflection on the assembly part required previously is no longer needed. This also eliminates the interface and the connecting elements required to bridge the interface and fasten the deformation tube to the assembly part. On the one hand, this allows reducing the costs for manufacturing and assembling the force limiter, and on the other hand, it improves the deflection itself by eliminating the need to deflect the tensile force transmission element via the interface.

[0012] It is further proposed that the displacement part includes a deformed portion which is non-circular in cross-section and has an outer dimension in at least one extension direction in the cross-section that is larger than the inner diameter of the deformed tube. Due to the non-circular cross-section of the displacement part in the region of the deformed portion, the deformation of the deformed tube occurs in a preferred direction defined by the shape of the deformed portion. The deformed tube is intentionally expanded unevenly on its circumference, and zones are intentionally created in the deformed tube in which the deformed tube deforms under higher loads with higher material stresses. This allows the use of cheaper materials or steels without risking the controlled deformation of the intentionally induced deformed tube.

[0013] In this case, the non-circular deformed portion may preferably have at least two radially outwardly projecting cams on its radially outer side in the cross-section. Thus, the deformed tube is intentionally widened in the region of the cams. Additionally, using the corresponding shape of the deformed tube, the cams can be used to align the displacement part in a defined position relative to the deformed tube. The cams on the side facing the deflection part or the guiding part of the displacement part can be designed in a ramp shape with a continuously decreasing outer dimension such that the deformation of the deformed tube occurs in an ascending manner.

[0014] It is further proposed that the non-circular deformed portion has at least two flat portions in the cross-section. The flat portions intentionally create a free space between the deformed tube and the displacement part, which allows the deformed tube to expand or contract into the displacement part during deformation.

[0015] It is further proposed that the cams and / or the flat portions are arranged diametrically opposite to each other such that the deformed tube is intentionally widened and deformed in its opposite portions.

[0016] Furthermore, the cams and / or the flat portions can be arranged equidistantly from each other above the circumference of the displacement part such that the deformed tube deforms as evenly as possible above the circumference and in the region of the cams within an as equal as possible range of plastic deformation.

[0017] It is further proposed that the displacement part has a cylindrical guiding part which has an outer diameter corresponding to the inner diameter of the deformed tube. The guiding part is used to align the displacement part in the installation position in the deformed tube and to guide the displacement part during the movement of the displacement part in the deformed tube. The guiding part intentionally has an outer diameter which corresponds to the inner diameter of the deformed tube taking into account the tolerances to be set such that the displacement part does not cause any deformation of the deformed tube in the region of the guiding part. The guiding part is arranged on the side of the deformed portion facing the deflection part.

[0018] It is further proposed that the deformation tube includes at least one radially inwardly formed bead in the region of the linear portion, and the bead restricts the displacement path of the displacement part in the deformation tube. The bead restricts the displacement movement of the displacement part; it actually forms a stop for the force-limited seat belt webbing extension.

[0019] It is further proposed that the assembly part includes a fastening portion for fastening the force limiter to the vehicle fixed structure, a first fixing portion including the deformation tube in the region of the linear portion, and a second fixing portion including the deformation tube in the region of the deflection portion. The design of the assembly part fixes the deformation tube in both the region of the linear portion and the region of the deflection portion. This fixes the deformation tube in the region of the linear portion to absorb the forces acting on the deformation tube in this region during deformation. In addition, the deformation tube is additionally fixed in the region of the deflection portion to absorb the forces acting during the deflection of the tension transmission element. In addition, the deformation tube is thus fixed in the region where the tension transmission element exits the deformation tube, which in turn facilitates the supply of the tension transmission element to the seat belt.

[0020] It is further proposed that the deformation tube is elliptical in the region of the open end of the deflection portion. Due to the elliptical shape of the open end of the deflection portion, the tension transmission element cannot move or can move less in the preferred direction, while the tension transmission element can be intentionally pivoted in the direction of the increasing opening width within a larger pivot angle range. The force limiter can preferably be fastened to the vehicle in such a way that the tension transmission element can perform a smaller movement transverse to the seat surface of the associated vehicle seat and is thus better aligned than in the longitudinal direction of the seat surface or in the travel direction.

[0021] It is further proposed that at least one additional deformation element or stop element is provided in the deformation tube for achieving an increasing or decreasing force limitation curve. By means of the additional deformation element or stop element, different force limitation curves can be achieved through the proper arrangement and sizing of the additional deformation element or stop element, provided that this is advantageous for restraining and especially for further reducing the occupant load.

[0022] It is further proposed that the position of the deformation element or stop element can be changed by means of a controllable actuator. This allows the force limitation curve to be actively changed and, for example, allows the force limitation curve to be adapted to the detected accident scenario or a specific occupant.

[0023] It is further proposed that a locking element is provided, which locks the displacement part and which can be moved from the locking position to the release position for releasing the displacement part by means of a controllable actuator. This allows the activation of the force limiter to be actively locked or released.

[0024] Alternatively or additionally, it is proposed to provide a locking element that locks the tensile force transmission element and that can be moved from a locked position to a release position releasing the tensile force transmission element by means of a controllable actuator. Activation of the force limiter can also be actively locked or released by locking or releasing the tensile force transmission element.

[0025] The invention will be explained below using preferred embodiments with reference to the drawings.

[0026] Figure 1 A force limiter according to the invention is shown, which has a buckle before assembly; and

[0027] Figure 2 A force limiter according to the invention with a buckle is shown in a side view; and

[0028] Figure 3 The displacement part of the force limiter is shown in different views; and

[0029] Figure 4a 、 Figure 4b The force limiter is shown in a view of the displacement part and in a sectional view in the sectional direction A-A of Figure 4a ; and

[0030] Figure 5a 、 Figure 5b The force limiter is shown in different sectional views, in which the displacement part is in the position before and after force limitation;

[0031] Figure 6a 、 Figure 6b The force limiter is shown in a sectional view, which has an additional actuator for influencing activation and the force limitation level;

[0032] Figure 7 Alternative embodiments of the displacement part are shown in different views.

[0033] Figure 1The exploded view of the force limiter 1 according to the present invention with the individual parts before assembly is shown. The force limiter 1 includes a deformation tube 2, a tensile force transmission element 3, a displacement part 4, and an assembly part 5. The tensile force transmission element 3 is connected to the displacement part 4 in a tensile manner at one end and is connected to the buckle ring 7 in a tensile manner at its other end. Instead of the buckle ring 7, an end fitting, a cable loop, a deflector, or another part of the seat belt device can also be provided, as long as it is combined with the tensile force transmission element 3 such that a force-limited extension of the seat belt can be achieved through the linear movement of the displacement part 4 in the deformation tube 2, as described below. The tensile force transmission element 3 is a rope, preferably a steel wire rope, which is inherently flexible and, due to its material properties and design, can absorb the tensile force occurring in the restraint situation without tearing itself or being mechanically damaged.

[0034] The deformation tube 2 has a straight linear part 21 and a curved deflection part 22 integrally formed with the linear part 21. The assembly part 5 is used to fasten the force limiter 1 to the vehicle and, for this purpose, has a plate-shaped fastening part 53 including a fastening opening. In addition, the assembly part 5 has a first fixing part 51 and a second fixing part 52, both of which are annular or clamp-shaped and are used to hold the deformation tube 2 on the assembly part 5, that is, to hold the deformation tube 2 fixed to the vehicle.

[0035] The assembly part 5 includes the deformation tube 2, which has an annular first fixing part 51 in the region of the linear part 21 at its end facing the deflection part 22. The size of the first fixing part 51 is intentionally set to be slightly longer and is therefore more tubular in shape, so that the deformation tube 2 is stably supported in the first fixing part 51. The second fixing part 52 of the assembly part 5 includes the deformation tube 2 in the region of the deflection part 22 and thus additionally fixes the deflection part 22 relative to the linear part 21. Thus, the deformation tube 2 is actually fixed in terms of its geometry by the two fixing parts 51 and 52.

[0036] The linear part 21 of the deformation tube 2 has an open end 25, which can be at Figure 4bAs can be seen, the displacement part 4 is arranged in or on the open end. The tensile force transmission element 3 is connected to the displacement part 4 in a tensile force-resistant manner and extends from the displacement part 4 first through the linear part 21 of the deformation tube 2 and then deflects in a predetermined direction in the deflection part 22 of the deformation tube 2, and the deflection part is integrally formed on the linear part 21. The deformation tube 2 is elliptical in the region of the open end 24 of the deflection part 22, so that the tensile force transmission element 3 can perform a greater movement, especially a pivoting movement, in the preferred direction than in the direction orthogonally oriented thereto. The preferred direction can correspond to the traveling direction and / or the longitudinal direction of the seat surface of the associated vehicle seat, so that the buckle ring 7 or the end fitting held on the tensile force transmission element 3 can intentionally perform a greater movement in the traveling direction or in the longitudinal direction of the seat surface and is restricted in the movement transverse to this direction.

[0037] The displacement part 4 includes a cylindrical guide part 41 having a circular cross-section and a deformation part 42 having a non-circular cross-section. The displacement part 4 further has a through-hole 426 through which the tensile force transmission element 3 extends. By thickening the protruding end, the tensile force transmission element 3 is squeezed, bonded or connected to the displacement part 4 in a tensile force-resistant manner in the through-hole. The guide part 41 has an outer diameter B which is the same as the inner diameter D of the linear part 21 of the deformation tube 2 taking into account the size deficiency, so that the displacement part 2 can be inserted into the open end 25 with the guide part 41 and abuts as flatly as possible against the inner wall of the linear part 21. The cross-section of the deformation part 42 is non-circular and has two cams 421 and 422 which are arranged diametrically opposite to each other on the radially outer side and are equidistant from each other in the circumferential direction, and two flat parts 423 and 424 which are arranged diametrically opposite to each other and are equidistant from each other in the circumferential direction. Due to the cams 421 and 422, the deformation part 42 has an outer dimension A which is larger than the inner diameter D of the linear part 21 of the deformation tube 2. The cams 421 and 422 are formed in a ramp-shaped manner rising outward from the guide part 41 on the edge side facing the edge of the deformation tube 2.

[0038] In addition, the deformation tube 2 has at least two diametrically opposite radially inwardly protruding bead rims or a circumferential bead rim 23 on the side of the linear part 21 facing the deflection part 22, and the sizes of these bead rims are set such that a gap is formed between their radially inner end faces, and the tensile force transmission element 3 extends through this gap. The gap formed by the bead rim 23 is used to guide the tensile force transmission element 3 and also to form a stop in order to limit the movement of the displacement part 4 during the extension of the force-limited seat belt webbing, and this movement will be elaborated in more detail below.

[0039] Furthermore, an additional conically tapering deformation element 6 in the form of a plastically deformable material is provided, which extends from the bead edge 23 in the direction of the open end 25 of the linear part 21 of the deformation tube 2.

[0040] In Figure 4b , the force limiter 1 can be seen in the sectional direction A - A before activation. The displacement part 4 is in its position where the guiding part 41 projects into the linear part 21 of the deformation tube 2, and the deformation part 42 is arranged outside the deformation tube 2 in the right - hand illustration in Figure 4a , that is, outside the open end 25 of the linear part 21. Figure 4b If in this position of the force limiter 1, a tensile force is applied via the seat belt to the tensile force transmission element 3 and this tensile force is greater than the plastic deformation limit of the deformation tube 2 in the region of the linear part 21, the displacement part 4 is pulled from the initial position into the

[0041] position 4' shown. The deformation tube 2 expands in the region of the linear part 21 by means of the cams 421 and 422 and thus plastically deforms. At the same time, the deformation tube 2 is laterally pulled towards the flat parts 423 and 424 in this region, as can be seen in the sectional view D - D in Figure 5a . The deformation tube 2 thus plastically deforms into a geometry corresponding to the cross - sectional geometry of the deformation part 42. The deformation part 42 serves for the plastic deformation of the deformation tube 2 in the region of the linear part 21, where it is not excluded that the deformation part 42 itself also deforms slightly. The deformation of the linear part 21 by means of the cams 421 and 422 occurs outwards in two preferred directions, while at the same time the linear part rests laterally against the flat parts 423 and 424. The plastic deformation of the deformation tube 2 is the basis for the energy absorption on which the force - limited extension of the tensile force transmission element is based. Figure 5b Due to the shape of the proposed displacement part 4, a defined stress state is generated during the movement of the displacement part 4, and a force - limited extension of the seat belt webbing is generated in the deformation tube 2 during plastic deformation, which enables an improved defined deformation of the deformation tube 2 even when using cheaper steel or material types to achieve a defined force - limiting level. This allows a further reduction in the cost of manufacturing the force limiter 1.

[0042] If a bead edge 23 and an additional deformation element 6 are provided as in this exemplary embodiment, the force - limited extension of the tensile force transmission element 3 can first be limited and then designed to increase gradually towards the end.

[0043]

[0044] In Figure 6b Figure 6a , the force limiter 1 can be seen in a further developed embodiment in the sectional direction A - A according to .

[0045] Various control devices 8, 9, and 10 are provided on the force limiter 1 for controlling the force limiter 1 and its force limiting curve. Thus, a control device 8 is provided, which has a locking element 81 that rests against the displacement part 4 in the locked position and locks the movement of the displacement part. The control device 8 further includes an actuator 82 that, when activated, moves the locking element 81 from the locked position to the released position, such that the displacement part 4 is then released to perform the above-mentioned movement.

[0046] In addition, a control device 9 is provided, which has a stop element 91 protruding into the travel path of the displacement part 4 and a controllable actuator 92 that moves the stop element 91 when activated. The stop element 91 can limit the travel path of the displacement part 4 and thus limit the force-limited belt extension length. Alternatively, the stop element 91 can be used as an additional deformation element, such as the conical deformation element 6, which plastically deforms intentionally when passing the displacement part 4 and thus causes an increase in the force limiting level. This allows different force limiting curves to be achieved depending on the position of the stop element 91 or the deformation element.

[0047] In addition, a control device 10 is provided, which has a locking element 11 that rests against or clamps the end of the tensile force transmission element 3 against the belt buckle 7 in the locked position. The control device 10 further includes an actuator 12 that, when activated, moves the locking element 11 from the locked position to the released position, in which the belt buckle 7 or the tensile force transmission element 3 is released.

[0048] The control devices 8, 9, and 10 can be provided on the force limiter 1 individually or in any combination. The actuators 12, 92, and 82 can be designed as electrically controllable drives or pyrotechnic drives using an electric ignition. In any case, the accident-specific and / or occupant-specific force limiting curves of the force limiter 1 can be set by the control devices 8, 9, and 10.

[0049] Figure 7 An alternative embodiment of the displacement part 4 with three cams 421, 422, and 425 is shown, which are arranged in a star shape and evenly distributed above the circumference. The three cams 421, 422, and 425 are arranged such that their centers are at an angle of 120 degrees to each other. The cams 421, 422, and 425 are shaped in a ramp-like manner towards the guide part 41 at their parts facing the guide part, such that the cams 421, 422, and 425 deform the deformation tube 2 with increasing plastic deformation during the force-limited movement.

Claims

1. A force limiter (1) for a seat belt of a seat belt device for a motor vehicle, the force limiter comprising - a mounting part (5), - a deformation tube (2), - a tensile force transmission element (3), and - a displacement part (4) which is connected to the tensile force transmission element (3) in a tension-resistant manner and is arranged in or on the deformation tube (2), wherein - the deformation tube (2) has a linear part (21), and the displacement part (4) is held in or at the open end (25) of the linear part, characterized in that - the deformation tube (2) has a deflection part (22) integrally formed with the linear part (21), and the tensile force transmission element (3) is deflected in the deflection part.

2. The force limiter (1) according to claim 1, characterized in that - the displacement part (4) includes a deformation part (42) which is non-circular in cross-section and has an outer dimension (A) in at least one extending direction in the cross-section that is larger than the inner diameter (D) of the deformation tube (2).

3. The force limiter (1) according to claim 2, characterized in that - the non-circular deformation part (42) includes at least two radially outwardly protruding cams (421, 422, 425) on its radially outer side in the cross-section.

4. The force limiter (1) according to any one of claims 2 or 3, characterized in that - the non-circular deformation part (42) has at least two flat parts (423, 424) on its radially outer side in the cross-section.

5. The force limiter (1) according to any one of claims 3 or 4, characterized in that - the cams (421, 422, 425) and / or the flat parts (423, 424) are arranged diametrically opposite to each other.

6. The force limiter (1) according to any one of claims 3 to 5, characterized in that - the cams (421, 422, 425) and / or the flat parts (423, 424) are arranged equidistantly from each other above the circumference of the displacement part (4).

7. The force limiter (1) according to any one of claims 1 to 6, characterized in that - the displacement part (4) has a cylindrical guiding part (41) which has an outer diameter (B) corresponding to the inner diameter (D) of the deformation tube.

8. The force limiter (1) according to any one of claims 1 to 7, characterized in that - the deformation tube (2) includes at least one radially inwardly formed bead edge (23) in the region of the linear part (21), and the bead edge limits the displacement path of the displacement part (4) in the deformation tube (2).

9. The force limiter (1) according to any one of claims 1 to 8, characterized in that - The assembly part (5) includes a fastening part (53) for fastening the force limiter (1) to a vehicle fixed structure, a first fixing part (51) including the deformation tube (2) in the region of the linear part (21), and a second fixing part (52) including the deformation tube (2) in the region of the deflection part (22).

10. The force limiter (1) according to any one of claims 1 to 9, characterized in that - The deformation tube (2) is elliptical in the region of the open end (24) of the deflection part (22).

11. The force limiter (1) according to any one of claims 1 to 10, characterized in that - At least one additional deformation element (6) or stop element (91) is provided in the deformation tube (2) to achieve an increasing or decreasing force limit curve.

12. The force limiter (1) according to claim 11, characterized in that - The position of the deformation element (6) or the stop element (91) can be changed by means of a controllable actuator (92).

13. The force limiter (1) according to any one of claims 1 to 12, characterized in that - A locking element (81) for locking the displacement part (4) is provided, and the locking element can be moved from a locking position to a release position for releasing the displacement part (4) by means of a controllable actuator (82).

14. The force limiter (1) according to any one of claims 1 to 13, characterized in that - A locking element (11) for locking the tensile force transmission element (3) is provided, and the locking element can be moved from a locking position to a release position for releasing the tensile force transmission element (3) by means of a controllable actuator (12).

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