Seat belt retractor for seat belt of motor vehicle

Abstract

The invention relates to a belt retractor for a seat belt of a motor vehicle, comprising: a belt shaft (2) rotatably mounted in a housing frame (1), the belt shaft (2) comprising an outlet slot (3); a belt webbing (4), one end of the belt webbing (4) being fastened in the belt shaft (2) and the belt webbing (4) being guided out of the belt shaft (2) through the outlet slot (3); a profile head (5) which can be locked with respect to the housing frame (1); and a force limiting device (6) which is arranged at least partially in the seat belt shaft (2), the seat belt webbing (4) adjoins the force limiting device (6) by 180 degrees or more in the circumferential direction, and the force limiting device (6) has a plurality of stages.

Description

[0001] manual

[0002] The invention relates to a seat belt retractor for a seat belt of a motor vehicle, the seat belt retractor comprising: a seat belt shaft, which is rotatably mounted in a housing frame, wherein the seat belt shaft comprises an outlet slot; a seat belt webbing, wherein one end of the seat belt webbing is fastened in the seat belt shaft and the seat belt webbing is guided out of the seat belt shaft through the outlet slot; a profile head, which can be locked relative to the housing frame; and a force limiting device, which is at least partially arranged in the seat belt shaft, wherein the seat belt webbing is adjacent to the force limiting device by 180° or more in the circumferential direction.

[0003] Such a belt retractor is known, for example, from DE 10 2009 037 176 A1. Such a belt retractor has an end ring at the end of the belt webbing, into which a torsion bar is inserted as an element of the force limiting device. The end ring of the belt webbing is thus directly attached to the torsion bar. By winding the torsion bar through 180°, a uniform load introduction can be ensured. In the belt retractor known from DE 10 2009 037 176 A1, force-limited extension of the belt webbing is only possible in one step during the twisting of the torsion bar.

[0004] The object of the present invention is to provide a belt retractor in which a force-limited extension of the belt webbing can take place at several levels, wherein the belt shaft simultaneously has a high breaking load.

[0005] This object is achieved by a seat belt retractor having the features of the independent claim. Advantageous developments of the seat belt retractor are specified in the dependent claims and in the description, wherein individual features of the advantageous developments can be combined with one another in a technically advantageous manner.

[0006] This object is achieved in particular by a belt retractor having the features mentioned at the outset, wherein the force limiting device has multiple stages.

[0007] In other words, the basic idea of ​​the present invention is that in a seat belt retractor with a multi-stage force limiting device, the seat belt webbing is adjacent to the force limiting device in the circumferential direction by 180° or more. Preferably, the seat belt webbing is adjacent to the force limiting device in the circumferential direction by more than 180°, for example more than 185° or more than 190°. This large wrap angle ensures that during the extension of the force-limited seat belt webbing, there is a uniform load distribution, especially in the longitudinal direction of the seat belt shaft. By means of a uniform load distribution, the seat belt shaft can be optimized to achieve a high breaking load. In particular, it can be achieved that even if the multi-stage force limiting device is arranged inside the seat belt shaft, the seat belt shaft is designed to have a maximum thickness at the largest possible circumferential angle.

[0008] In a preferred embodiment, the force limiting device comprises a sleeve arranged in the belt shaft, wherein the sleeve is connected to the belt shaft for co-rotation, and wherein the belt webbing abuts the outer side of the sleeve. Thus, the belt webbing is guided out of the belt shaft through the outlet slot and is arranged inside the belt shaft between the outer side of the sleeve and the inner side of the belt shaft. The belt webbing abuts the sleeve by 180° or more in the circumferential direction. Thus, the belt webbing does not act directly on a force limiting element, which is designed as a torsion bar, for example, but on a rigid sleeve, which is connected to the belt shaft in a suitable manner for co-rotation, in particular in the initial state, and on the outer side of which the belt webbing is wound. Specifically, the belt webbing abuts the outer side of the sleeve by more than 180° and less than 225° in the circumferential direction. It can be arranged so that the connection of the sleeve to the belt shaft for co-rotation is released by means of a switching device, so that after the switching process, the belt shaft performs a rotational movement relative to the sleeve via at least one torsion bar during force limitation.

[0009] In a preferred embodiment, the force limiting device comprises at least two, preferably exactly two or exactly three torsion bars, which are arranged at least in a section in the belt shaft and preferably in a sleeve. Depending on the coupling of the torsion bars, different levels during force-limited belt webbing extension can be provided, depending on whether one or both of the two torsion bars are coupled to the housing frame during force-limited belt extension.

[0010] In order to switch between force limiting levels during extension of a force-limited seat belt webbing, a switching device is proposed, which can be used to switch between the various stages of the force limiting device. Force limiting devices with several force limiting levels and associated switching devices are known in the prior art, but not in combination with a seat belt webbing that is wound around the force limiting device by more than 180°.

[0011] In particular, one end of each torsion bar is connected to the belt shaft for co-rotation or, if necessary, can be connected via a switching device. It can also be arranged that at least one end of at least one torsion bar is connected to the profile head for co-rotation. Thus, the coupling of the at least one torsion bar to the housing frame can preferably be achieved by means of the profile head, for which purpose the at least one torsion bar is connected or connectable to the profile head for co-rotation on the one hand and to the belt shaft for co-rotation on the other hand. During the force-restricted relative rotation, the end of the torsion bar connected to the profile head will therefore be coupled to the housing frame for co-rotation.

[0012] In a preferred embodiment, it is proposed that the end of the belt webbing forms an end loop, into which the rod element is inserted, so that the end of the belt webbing is fastened in the belt shaft. The force limiting device is therefore not arranged in the end loop itself. In this case, in particular, the belt shaft comprises a belt webbing end holder, in which the rod element and therefore the end loop of the belt webbing is fastened.

[0013] In a preferred embodiment, the exit slot is spaced apart from the belt webbing end retainer by more than 220° in the circumferential direction, wherein the belt webbing is wound around the force limiting device. This distance is measured on the outer circumferential surface of the belt shaft. The distance between the belt webbing end retainer and the exit slot should not be more than 300°, preferably not more than 270°. This distance ensures that the belt webbing is wound around the force limiting device inside the belt shaft by more than 180°. The exit slot is arranged on the same side of the belt shaft as the belt webbing end retainer. In this case, in particular, the belt shaft includes only the belt webbing end retainer as a groove extending from the outside of the belt shaft to the inside of the belt shaft, in addition to the exit slot. In addition to the belt webbing end retainer and the exit slot, there is no groove extending from the inside to the outside on the belt shaft.

[0014] The exit slot and the belt webbing end retainer are also particularly arranged and designed such that they are spaced apart from each other by at least 45°, preferably at least 60° but not more than 70° in the circumferential direction on the inside of the belt shaft (i.e. in the area of ​​the belt not adjoining the force limiting device). This means that at least under load, there is still a relatively large area where the sleeve of the force limiting device can directly abut the inside of the belt shaft.

[0015] In a preferred embodiment, the height of the exit slot is between 200% and 500% of the thickness of the seat belt webbing. Specifically, the height is between 250% and 300% of the thickness of the seat belt webbing. The height should be determined at a position in the exit slot that is at right angles to the plane of the seat belt webbing.

[0016] The outlet slot is particularly arranged such that the outlet slot extends parallel to a tangent to the inside of the belt shaft, which tangent is (imaginarily) arranged in the region where the outlet slot penetrates the inside of the belt shaft. It can also be arranged such that a step is formed at the transition from the outlet slot to the inside of the shaft. Thus, the direction of extension of the outlet slot (in the direction in which the belt webbing extends) is tangent to a point on the inside of the belt shaft at which the outlet slot penetrates the inner circumferential surface of the belt shaft.

[0017] The belt webbing adjoins the force limiting device, in particular the sleeve of the force limiting device, in a first circumferential region and in a second circumferential region adjoining the first circumferential region. In a preferred embodiment, the circumferential regions differ in that the belt shaft has a different thickness in the first circumferential region than in the second circumferential region. Thickness refers to the strength of the belt shaft in a radial analysis. Thus, the thickness is the difference between the outer diameter and the inner diameter at the relevant point on the belt shaft. Thus, the belt shaft has different strengths.

[0018] The first circumferential region is also characterized in particular in that the belt webbing is arranged in two layers therein. In order to form an end loop for receiving the rod element, the belt webbing extends in two layers for a certain distance, which preferably defines the first circumferential region.

[0019] In a preferred embodiment, 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. Thus, the strength of the belt shaft can be optimized to be as large as possible.

[0020] The thickness of the belt shaft need not change suddenly at a certain point, but can increase gradually. In this regard, the thickness of the belt shaft in the second circumferential region increases from the thickness of the belt shaft in the first circumferential region to the maximum thickness in the second circumferential region.

[0021] It is also preferred that the second circumferential region is shorter in the circumferential direction than the first circumferential region.

[0022] The exit slot and the belt webbing end holder are in particular spaced apart from one another in such a way that, at least under load, the sleeve abuts the belt shaft in a region where the belt webbing does not abut the force limiting device. Thus, under load, forces can be introduced directly from the sleeve into the belt shaft. Since the sleeve extends over the entire length of the belt shaft, a uniform load distribution of the forces introduced into the belt shaft via the belt webbing and the sleeve can be achieved.

[0023] In this case, it is particularly preferred that the sleeve adjoins the shaft in the circumferential direction by at least 45°, preferably at least 60° but not more than 90°.

[0024] The present invention and the technical environment are explained exemplarily below with reference to the accompanying drawings. Schematically, in the accompanying drawings:

[0025] Figure 1 It is an exploded view of the seat belt retractor;

[0026] Figure 2 is a perspective view of a seat belt shaft and sleeve of a seat belt retractor;

[0027] Figure 3 is a cross-sectional view through the belt shaft and sleeve;

[0028] Figure 4 is another cross-sectional view through the belt shaft and sleeve;

[0029] Figure 5 showing a safety belt shaft with a transport lock; and

[0030] Figure 6 Another embodiment of a transport lock on a belt shaft is shown.

[0031] Figure 1 A seat belt retractor is shown which comprises a housing frame 1. A seat belt shaft 2 is rotatably mounted in the housing frame 1. The seat belt retractor further comprises a profile head 5 which can be locked relative to the housing frame 1.

[0032] The seat belt retractor further comprises a force limiting device 6 which in turn comprises a sleeve 6.1, a first torsion bar 6.2 and a second torsion bar 6.3.

[0033] The belt retractor further comprises a switching device 12, with which a switch can be made between force limitation levels predetermined by the torsion bars 6.2 and 6.3 during a force-limited relative rotation of the belt shaft 2 relative to the housing frame 1. Such belt retractors are known.

[0034] from Figures 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 retainer 8 .

[0035] The belt webbing 4 can be screwed into the belt shaft 2 through the belt webbing end holder 8, wherein the belt webbing 4 is led out of the exit slot 3. After the end ring 4.1 into which the rod element 7 is inserted has been pulled into the belt webbing end holder 8 and thus secured in the belt shaft 2, the belt webbing 4 is wound onto the belt shaft 2.

[0036] Especially from Figure 4It can be seen that the belt webbing 4 abuts the outer side of the sleeve 6.1 in the first circumferential region 9.1 and in the second circumferential region 9.2. In the first circumferential region 9.1, the thickness of the belt shaft 2 is less than the thickness of the belt shaft in the second circumferential region 9.2. This thickness corresponds to the strength of the belt shaft 2 and therefore 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 towards the exit slot 3.

[0037] Thus, the thickness of the belt shaft 2 in the second region 9.2 can be greater 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 inside of the shaft 2 over its entire length, a uniform load distribution over the length of the belt shaft 2 is possible.

[0038] In the case of the load outlet slot, and in particular at the force-limited end, the sleeve 6.1 abuts the inner side of the belt shaft 2 in the region where the belt webbing 4 does not abut the sleeve 6.1. In this region, during the extension of the force-limited belt webbing, forces are transmitted from the sleeve 6.1 to the belt shaft 2. Since the belt webbing 4 abuts the outer side of the sleeve 6.1 by more than 180° in the circumferential direction, forces are introduced uniformly from the sleeve 6.1 into the belt shaft 2, so that the forces are evenly distributed.

[0039] Figure 5 and Figure 6 Two embodiments of a transport lock 13 are shown. The transport lock 13 serves to secure the belt shaft 2 in the housing frame 1 and prevents a rotation between individual installation steps. Typically, after mounting the belt retractor, the spring of the belt shaft 2 is tensioned and secured 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 abuts in the belt webbing end holder 8. The second end of the belt webbing 4 emerges from the exit slot 3 and, after the transport lock 13 has been released, is wound up onto the belt shaft 2 by the spring tension of the tensioning spring. According to Figure 5 In the first embodiment, a gap is formed in the belt shaft 2, and the transport lock 13 is inserted into the gap. Figure 6 The transport lock 13 is plugged onto the belt shaft 2 and has a groove at its upper end facing away from the belt shaft 2 , which groove couples elements of the housing frame 1 during insertion.

[0040] Reference numerals list

[0041] 1 Shell frame

[0042] 2 Seat belt shaft

[0043] 2.1 Groove

[0044] 3 Exit slot

[0045] 4 Seat belt webbing

[0046] 4.1 End ring

[0047] 5 Profile head

[0048] 6 Force Limiting Devices

[0049] 6.1 Sleeve

[0050] 6.2 First torsion bar

[0051] 6.3 Second torsion bar

[0052] 7-bar element

[0053] 8 Seat belt webbing end retainer

[0054] 9.1 The first circumferential area

[0055] 9.2 Second Circumferential Area

[0056] 10. Thickness

[0057] 11 Height

[0058] 12 Switching devices

[0059] 13 Transport lock

Claims

1. A seat belt retractor for a seat belt of a motor vehicle, the seat belt retractor comprising - a belt shaft (2) which is rotatably mounted in the housing frame (1), wherein the belt shaft (2) comprises an exit slot (3), a seat belt webbing (4), wherein one end of the seat belt webbing (4) is fastened in the seat belt shaft (2) and the seat belt webbing (4) is guided out of the seat belt shaft (2) through the exit slot (3), - a profile head (5) which can be locked relative to the housing frame (1), and a force limiting device (6) which is at least partially arranged in the belt shaft (2), wherein The seat belt webbing (4) is adjacent to the force limiting device (6) by 180° or more in the circumferential direction, It is characterized in that The force limiting device (6) has multiple stages.

2. A seat belt retractor according to claim 1, wherein the force limiting device (6) comprises a sleeve (6.1) arranged in the seat belt shaft, wherein the sleeve (6.1) is connected or can be connected, in particular detachably, to the seat belt shaft (2) for common rotation, and wherein the seat belt webbing (2) is adjacent to the sleeve (6.1).

3. The seat belt retractor according to claim 2, wherein the seat belt webbing (4) abuts the outer side of the sleeve (6.1) by more than 180° but less than 225° in the circumferential direction.

4. A seat belt retractor according to any one of the preceding claims, wherein the end of the seat belt webbing (4) forms an end ring (4.1), into which a rod element (7) is inserted for fastening the end of the seat belt webbing (4) in the seat belt shaft (2).

5. A seat belt retractor according to any one of the preceding claims, wherein the seat belt shaft (2) comprises a seat belt webbing end retainer (8), wherein the exit slot (3) and the seat belt webbing end retainer (8) are spaced apart from each other by more than 220° in the circumferential direction, and wherein the seat belt webbing (4) is also wound around the force limiting device (6).

6. A seat belt retractor according to any one of the preceding claims, wherein the seat belt webbing (4) is adjacent to the force limiting device (6) in a first circumferential area (9.1) and in a second circumferential area (9.2) adjacent to the first circumferential area (9.1), wherein the seat belt shaft (2) has a different thickness (10) in the first circumferential area (9.1) than in the second circumferential area (9.2).

7. The seat belt retractor according to claim 6, wherein the thickness (10) of the seat belt shaft (2) in the second circumferential region (9.2) is between 110% and 130% of the thickness (10) of the seat belt shaft (2) in the first circumferential region (9.1).

8. The seat belt retractor according to claim 6 or claim 7, wherein the second circumferential region (9.2) is shorter than the first circumferential region (9.1) in the circumferential direction.

9. A belt retractor according to claim 2 or a claim referring back to claim 2, wherein at least under load, the sleeve (6.1) abuts the belt shaft (2) in an area in which the belt webbing (4) does not abut the force limiting device (6).

10. The belt retractor according to claim 9, wherein the sleeve (6.1) adjoins the belt shaft (2) by at least 45°, preferably at least 60° in the circumferential direction.

11. A seat belt retractor according to any one of the preceding claims, wherein in addition to the exit slot (3), the seat belt shaft (2) comprises only the seat belt webbing end retainer (8) as a groove extending from the outside of the seat belt shaft (2) to the inside of the seat belt shaft (2).

12. A seat belt retractor according to any one of the preceding claims, wherein the height (11) of the exit slot (3) is between 200% and 500% of the thickness of the seat belt webbing (4).

13. The seat belt retractor according to any one of the preceding claims, wherein the outlet slot (3) extends parallel to a tangent to the inner side of the belt shaft (2), the tangent being placed in a region in which the outlet slot (3) penetrates the inner side of the belt shaft (2).

14. The belt retractor according to claim 1, wherein the force limiting device (6) comprises at least two torsion bars (6.2, 6.3), which are arranged at least in a section in the belt shaft (2) and preferably in the sleeve (6.1).

15. The belt retractor according to claim 1, wherein the belt retractor comprises at least one switching device (12) by means of which switching between the stages of the force limiting device (6) can be carried out.

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