BELT RETRACTOR FOR A SAFETY BELT OF A MOTOR VEHICLE

Abstract

The invention relates to a belt retractor for a seat belt of a motor vehicle, comprising: a belt shaft which is rotatably mounted in a housing frame, wherein the belt shaft comprises an exit slot; a belt webbing, wherein one end of the belt webbing is fastened in the belt shaft and the belt webbing is guided out of the belt shaft through the exit slot; a profile head which can be locked in relation to the housing frame; and a force-limitation device which is at least in part arranged in the belt shaft, wherein the belt webbing abuts the force-limitation device in the circumferential direction for 180 or more, wherein the force-limitation device has multiple stages.

Claims

1. Belt retractor for a seat belt of a motor vehicle, comprising a belt shaft which is rotatably mounted in a housing frame, wherein the belt shaft comprises an exit slot, a belt webbing, wherein one end of the belt webbing is fastened in the belt shaft and the belt webbing is guided out of the belt shaft through the exit slot, a profile head which can be locked in relation to the housing frame, and a force-limitation device which is at least in part arranged in the belt shaft, wherein the belt webbing abuts the force-limitation device in the circumferential direction for 180 or more, wherein the force-limitation device has multiple stages.

2. The belt retractor according to claim 1, wherein the force-limitation device comprises a sleeve arranged in the belt shaft, wherein the sleeve is or can be in particular detachably connected to the belt shaft for conjoint rotation, and wherein the belt webbing abuts the sleeve.

3. The belt retractor according to claim 2, wherein the belt webbing abuts an outer side of the sleeve in the circumferential direction for more than 180 but less than 225.

4. The belt retractor according to claim 1, wherein the end of the belt webbing forms an end loop into which a rod element is inserted for fastening the end of the belt webbing in the belt shaft.

5. The belt retractor according to claim 1, wherein the belt shaft comprises a belt webbing end holder, wherein the exit slot and the belt webbing end holder are spaced apart from one another in the circumferential direction, in which the belt webbing also wraps around the force-limitation device, by more than 220.

6. The belt retractor according to claim 1, wherein the belt webbing abuts the force-limitation device in a first circumferential region and in a second circumferential region adjoining the first circumferential region, wherein the belt shaft has a different thickness in the first circumferential region than in the second circumferential region.

7. The belt retractor according to claim 6, wherein the thickness of the belt shaft in the second circumferential region is between 110% and 130% of the thickness of the belt shaft in the first circumferential region.

8. The belt retractor according to claim 6, wherein the second circumferential region is shorter in the circumferential direction than the first circumferential region.

9. The belt retractor according to claim 2, wherein the sleeve abuts the belt shaft in a region in which the belt webbing does not abut the force-limitation device, at least in the case of a load.

10. The belt retractor according to claim 9, wherein the sleeve abuts the belt shaft in the circumferential direction over at least 45, preferably over at least 60.

11. The belt retractor according to claim 1, wherein, in addition to the exit slot, the belt shaft comprises exclusively the belt webbing end holder as recesses that extend from an outer side of the belt shaft (2) to an inner side of the belt shaft.

12. The belt retractor according to claim 1, wherein a height of the exit slot is between 200% and 500% of a thickness of the belt webbing.

13. The belt retractor according to claim 1, wherein the exit slot extends parallel to a tangent of an inner side of the belt shaft which is placed in a region in which the exit slot penetrates the inner side of the belt shaft.

14. The belt retractor according to claim 1, wherein the force-limitation device comprises at least two torsion bars that are arranged at least in sections in the belt shaft and preferably in the sleeve.

15. The belt retractor according to claim 1, wherein the belt retractor comprises at least one switching apparatus by means of which it is possible to switch between the stages of the force-limitation device.

Description

[0023] The invention and the technical environment are explained below by way of example with reference to the figures. Schematically, in the figures:

[0024] FIG. 1 is an exploded view of a belt retractor;

[0025] FIG. 2 is a perspective view of a belt shaft and a sleeve of the belt retractor;

[0026] FIG. 3 is a sectional view through the belt shaft and the sleeve;

[0027] FIG. 4 is another sectional view through the belt shaft and the sleeve;

[0028] FIG. 5 shows a belt shaft with a transport lock; and

[0029] FIG. 6 shows another embodiment of a transport lock on a belt shaft.

[0030] FIG. 1 shows a belt retractor which comprises a housing frame 1. A belt shaft 2 is rotatably mounted in the housing frame 1. The belt retractor also comprises a profile head 5, which can be locked in relation to the housing frame 1.

[0031] The belt retractor also comprises a force-limitation device 6, which in turn comprises a sleeve 6.1, a first torsion bar 6.2 and a second torsion bar 6.3.

[0032] The belt retractor also comprises a switching apparatus 12, with which it is possible to switch between force-limitation levels, which are predetermined by the torsion bars 6.2 and 6.3, during a force-limited relative rotation of the belt shaft 2 in relation to the housing frame 1. Such belt retractors are well known.

[0033] From FIGS. 2 to 4, it can be seen that the belt shaft 2 has an exit slot 3 with a height 11 and a belt webbing end holder 8.

[0034] A belt webbing 4 can be threaded through the belt webbing end holder 8 into the belt shaft 2, wherein the belt webbing 4 exits from the exit slot 3. After the end loop 4.1, into which a rod element 7 is inserted, has been pulled into the belt webbing end holder 8 and is thus fastened in the belt shaft 2, the belt webbing 4 is wound up on the belt shaft 2.

[0035] As can be seen in particular from FIG. 4, the belt webbing 4 abuts an outer side of the sleeve 6.1 in a first circumferential region 9.1 and in a second circumferential region 9.2. In the first circumferential region 9.1, the belt shaft 2 has a thickness which is less than a thickness of the belt shaft in the second circumferential region 9.2. The thickness corresponds to the strength of the belt shaft 2 and thus to the difference in radius between the outer circumference and the inner circumference of the belt shaft 2 at the relevant point. It can also be seen that the thickness 10 of the belt shaft increases starting from the first circumferential region 9.1 in the second circumferential region 9.2 toward the exit slot 3.

[0036] The thickness of the belt shaft 2 can thus be greater in the second region 9.2 than in the first region 9.1. Thus, despite the arrangement of two torsion bars inside the sleeve 6.1, a large thickness of the belt shaft 2 can be achieved. Since the sleeve 6.1 abuts the inner side of the shaft 2 over its entire length, an even load distribution over the length of the belt shaft 2 is possible.

[0037] In the case of a load exit slot and in particular at the end of the force limitation, the sleeve 6.1 comes to abut the inner side of the belt shaft 2, in a region in which the belt webbing 4 does not abut the sleeve 6.1. In this region, force is transmitted from the sleeve 6.1 to the belt shaft 2 during the force-limited belt webbing extension. Since the belt webbing 4 abuts an outer side of the sleeve 6.1 in the circumferential direction for more than 180, the force is evenly introduced from the sleeve 6.1 into the belt shaft 2, so that the force is evenly distributed.

[0038] FIGS. 5 and 6 show two embodiments of a transport lock 13. The transport locks 13 serve to secure the belt shaft 2 in the housing frame 1 against rotation between individual installation steps. Usually, after installing the belt retractor, the spring of the belt shaft 2 is tensioned and fixed with the transport lock 13. In a further installation step, the belt webbing 4 with the end loop 4.1 and the rod element 7 with its free end are inserted through the belt webbing end holder 8 until the end loop comes to abut in the belt webbing end holder 8. The second end of the belt webbing 4 emerges from the exit slot 3 and is subsequently rolled up onto the belt shaft 2 by the spring tension of the tensioned spring after the transport lock 13 has been released. In accordance with the first embodiment in FIG. 5, a gap is formed in the belt shaft 2, into which the transport lock 13 is inserted. The transport lock 13 in accordance with FIG. 6, however, is plugged onto the belt shaft 2 and has a recess at its upper end facing away from the belt shaft 2, which, when inserted, comes to abut an element of the housing frame 1.

LIST OF REFERENCE SIGNS

[0039] 1 Housing frame [0040] 2 Belt shaft [0041] 2.1 Recess [0042] 3 Exit slot [0043] 4 Belt webbing [0044] 4.1 End loop [0045] 5 Profile head [0046] 6 Force-limitation device [0047] 6.1 Sleeve [0048] 6.2 First torsion bar [0049] 6.3 Second torsion bar [0050] 7 Rod element [0051] 8 Belt webbing end holder [0052] 9.1 First circumferential region [0053] 9.2 Second circumferential region [0054] 10 Thickness [0055] 11 Height [0056] 12 Switching apparatus [0057] 13 Transport lock