Belt retractor comprising a force-limiting device

Abstract

The invention relates to a belt retractor for a seat belt of a motor vehicle, comprising a belt shaft (1), which is mounted in a housing frame (11) so as to be rotatable about a rotational axis, and at least one first force-limiting device (2), wherein the first force-limiting device (2) comprises at least one torsion bar (3) situated outside the belt shaft (1) and a driver (4) connected to the at least one torsion bar (3); the at least one torsion bar (3) is coupled, in particular at a first end thereof, to the driver (4) by means of a gear (12) and is secured, at the other end thereof, against rotation relative to the housing frame (11); the driver (4) has a toothing (16) on the outer circumference thereof; and the belt retractor has at least one pre-fixing element (15.1, 15.2, 15.3), the driver (4) being held by the at least one pre-fixing element (15.1, 15.2, 15.3).

Description

[0001] Seatbelt retractor with force limiting device

[0002] The present invention relates to a belt retractor for a motor vehicle seat belt, comprising a belt shaft rotatably mounted about an axis of rotation in a housing frame and at least one first force limiting device. The first force limiting device particularly includes at least one force limiting element, a driver connected to the at least one force limiting element, a coupling element rotating with the belt shaft, and / or a locking unit comprising at least one locking element.

[0003] During normal use of the seatbelt retractor in a motor vehicle, the seatbelt is wound onto and unwound from the belt shaft when being fastened and unfastened, with the belt shaft rotating around its (virtual) axis of rotation. In this normal use, no force-limiting device is involved in the rotation of the belt shaft. However, in a critical situation triggered by strong deceleration of the vehicle, belt extension can occur, deforming at least one force-limiting element. For this to happen, the belt shaft is coupled to the housing frame via the at least one force-limiting element involved. To provide multiple force-limiting levels, several force-limiting devices can be provided, which participate in the force-limited belt extension simultaneously or sequentially.It may be provided that a (possibly second) force limiting device has several (at least two) force limiting elements, which can also participate simultaneously or sequentially in the force-limited belt extension. To couple the force limiting elements to the belt shaft for the force-limited belt extension, triggering devices may be provided that are mechanically implemented in a vehicle-sensitive or belt extension-sensitive manner, or that can be triggered electronically at a predetermined time.

[0004] In one embodiment, it may be provided that, in a force-limiting state of the belt retractor, the driver is connected to the coupling element in a rotationally fixed manner via the at least one locking element, so that the driver rotates with the belt shaft and the at least one force-limiting element is fixed at one end against rotation with the belt shaft and is deformed due to the rotational movement of the driver.

[0005] The at least one force-limiting element of the first force-limiting device is preferably designed as a torsion bar. The force-limiting element designed as a torsion bar is coupled to the driver at its first end and fixed at its other end against rotation relative to the housing frame, so that the torsion bar is deformed by the rotation of the belt shaft, at least in the force-limiting state of the first force-limiting device. For example, the driver may have teeth on its outer circumference, and the torsion bar may be coupled to the driver by means of a gear, so that, at least in the force-limiting state of the first force-limiting device, a rotation of the driver is transmitted to the torsion bar via the gear. The gear may be connected to the torsion bar, for example, by crimping, either by friction or positive locking.In this context, it can be provided that the fixed end of the torsion bar is inserted directly, and in particular positively, into the housing frame. The end carrying the gear can be rotatably mounted in a housing for the first force limiting device and / or in the housing frame, the housing being of two or more parts. For example, the torsion bar can be inserted with its fixed end through a first part of the housing, and the gear can be covered by a lid-shaped part of the housing, with a projection extending beyond the gear being mounted in the lid-shaped part.

[0006] It may be provided, in particular, that in addition to the first force limiting device, a second, especially multi-stage, force limiting device is provided, which can be coupled on the one hand to a profile head that can be locked against the housing frame and on the other hand to the belt shaft, wherein the second force limiting device also allows force-limited relative rotation of the belt shaft with respect to the locked profile head. The force limiting elements of the second force limiting device are, in particular, torsion bars which are arranged coaxially within the belt shaft.

[0007] In a simple embodiment, the second force-limiting device comprises exactly one torsion bar, while in a preferred embodiment, the second force-limiting device comprises two or three torsion bars, and a switching device may be provided to control which of the torsion bars participates in the force-limited relative rotation of the belt shaft. The belt retractor is particularly configured such that, for an initial force-limited relative rotation, the belt shaft is coupled to the housing frame by means of the second force-limiting device, while the first force-limiting device is engaged for the force-limited relative rotation as needed or at a later time by means of the electronically triggerable release device.

[0008] The present disclosure relates in particular to the coupling of the driver of the first force-limiting device with the coupling element of the belt shaft. In an initial state of the first force-limiting device, the belt shaft can rotate freely relative to the driver. To involve the first force-limiting device in the force-limited relative rotation, the coupling element, which is rotationally fixed to the belt shaft, can be connected to the driver by means of a locking element of a locking unit. During the subsequent relative rotation of the belt shaft with respect to the housing frame, the driver rotates with the belt shaft, whereby the at least one force-limiting element connected to the driver, in particular the torsion bar, is deformed under energy absorption.

[0009] The coupling element can, for example, be integrally connected to the belt shaft. However, it is preferred that the coupling element be provided as a separate component, which is at least indirectly connected to the belt shaft. The coupling element can, for example, be mounted on a projection on the belt shaft in a rotationally fixed manner.

[0010] It can further be provided that the at least one locking element for bringing about the force-limiting state is radially deflectable by a relative movement between the coupling element and the driver, wherein the at least one locking element, in a deflected position, connects the driver to the coupling element in a rotationally fixed manner. Thus, the locking element of the locking unit can be offset axially relative to the axis of rotation defined by the belt shaft for the rotationally fixed connection of the driver to the coupling element. The connection of the driver to the coupling element is therefore effected by a movement of the locking element in a radial direction. For this purpose, the locking element can be provided with a kind of chamfer which deflects the locking element radially outwards when the coupling element is rotatable relative to the locking unit to initiate the force-limiting state.The locking unit is also described in DE 10 2023 103 162 Al, so that its elements and function are applicable to the belt retractor described here.

[0011] In one embodiment, the first force-limiting device comprises a release mechanism, preferably electronically triggered and preferably pyrotechnically actuated, for triggering a transition of the first force-limiting device from an initial state to the force-limiting state. In the initial state, the belt shaft is rotatably mounted, particularly relative to the initially stationary driver. For this purpose, the release mechanism comprises, in particular, a locking element, preferably actuated by the pyrotechnic drive.

[0012] In one embodiment, the first force limiting device comprises a (gear) gear element on which the locking unit is mounted. The gear element has, in particular, outwardly projecting teeth on its outer circumference, and the release device is designed and arranged such that an element of the release device can interact with the teeth of the gear element. The gear element is designed and arranged such that, in the initial state, it is rotationally fixed to the belt shaft, so that in the initial state the locking unit, together with the gear element, can rotate with the belt shaft. The release device can lock the gear element, and thus the locking unit, relative to the housing frame to trigger the transfer. The release device can therefore stop any initial rotation of the gear element, and thus of the locking unit, relative to the housing frame.

[0013] The wheel element is connected to the belt shaft, at least indirectly, by means of a first predetermined breaking point. The wheel element is destroyed at this predetermined breaking point when it is locked in place by the release mechanism. Thus, the wheel element is connected to the belt shaft in such a way that the rotationally fixed connection between the wheel element and the belt shaft, present in the initial state, is released by the further relative rotation of the belt shaft with respect to the locked wheel element. During the subsequent relative rotation of the coupling element with respect to the locked wheel element and the locking element, the radial deflection of at least one locking element towards the drive lug occurs.

[0014] Once the locking element has connected the coupling element to the driver in a rotationally fixed manner, the locking element is also driven along by the further rotation of the belt shaft. The at least one locking element of the locking unit is therefore arranged such that, when the wheel element is fixed, it is deflected radially by the coupling element rotating with the belt shaft and engages with the driver. To enable the at least one locking element to rotate with the driver and the coupling element during the further rotation of the belt shaft, the locking unit has, in particular on an outer circumference of a bearing section, which is in particular annular, positive locking features that interact with a second predetermined breaking feature formed on the wheel element, so that the second predetermined breaking feature is destroyed and thus the locking unit can rotate relative to the fixed wheel element and the belt shaft.The locking unit is therefore preferably designed and connected to the wheel element, particularly initially via the second predetermined breaking feature, in such a way that the rotationally fixed connection of the locking unit with the wheel element present in the initial state is released by the relative rotation of the locking unit relative to the wheel element after the engagement of the locking element with the driver.

[0015] The first force limiting device comprises, in particular, a housing in which the release mechanism may be installed. The housing also has, in particular, a circular receptacle into which the wheel element with the locking unit can be inserted.

[0016] A seatbelt retractor with a first force limiting device and a second force limiting device is known, for example, from WO 2020 021 003 Al. In this seatbelt retractor, the second force limiting device also has a torsion bar as a force limiting element. Another seatbelt retractor with the features of the preamble of claim 1 is known from DE 10 2023 103 162 Al.

[0017] The belt retractors are usually installed manually. It has been found that ensuring the correct alignment of the drive teeth with the torsion bar gear is a time-consuming process.

[0018] The object of the present invention is therefore to provide a belt retractor that is easier and, in particular, safer to install.

[0019] One solution to this problem is given by the belt retractor with the features of independent claim 1, with further solutions and advantageous embodiments explained in the preceding and following description as well as in the dependent claims. Individual features of the advantageous embodiments can be combined with one another in a technically meaningful manner.

[0020] The problem is solved in particular by a belt retractor for a motor vehicle seat belt, which has a belt shaft rotatably mounted about an axis of rotation in a housing frame and at least one first force limiting device, wherein the first force limiting device comprises at least one torsion bar arranged outside the belt shaft and a driver connected to the at least one torsion bar. The at least one torsion bar of the first force limiting device is preferably coupled to the driver at a first end of the gear and fixed at its other end against rotation relative to the housing frame, wherein the driver has teeth on its outer circumference that engage with the gear.

[0021] It is proposed that the belt retractor have at least one pre-fixing element by which the driver is held, particularly during assembly. The at least one pre-fixing element is designed and / or aligned in such a way that the driver's mounting is released, for example, by deflection or destruction of the pre-fixing element, when the first force-limiting device is moved into its force-limiting state.

[0022] In other words, the invention essentially provides that the drive element is pre-assembled by the at least one pre-fixing element in an orientation specified, in particular by the at least one pre-fixing element, so that the gear and, in particular, the torsion bar connected to the gear are mounted on the belt retractor in an orientation specified by the pre-fixed drive element. For example, it can be provided that, due to the at least one pre-fixing element, the drive element is oriented such that the torsion bar with the attached gear can be inserted in such a way that its end, which is to be fixed against rotation, is inserted into a corresponding receptacle in the housing frame and / or a housing part. The at least one pre-fixing element thus simplifies the assembly of the belt retractor and helps to avoid assembly errors.

[0023] The at least one pre-fixing element is formed, in particular, as a single piece from a housing part of the belt retractor. This pre-fixing element can, for example, be formed by a projection such as a nose or a pin, whereby the position of the drive element is defined by the pre-fixing element and rotation of the drive element is prevented, at least during assembly and in the initial state. For example, to define an orientation, a projection can be formed in the circumferential direction of the drive element's teeth, both in front of and behind each tooth. Forming the pre-fixing element as a single piece with the housing part simplifies the manufacturing process, as the pre-fixing element can be formed on the housing part during production, particularly by injection molding.

[0024] It can also be provided that the at least one pre-fixing element covers or accommodates a tooth of the drive gear. The at least one pre-fixing element is thus not only arranged circumferentially in front of or behind a tooth, but also extends circumferentially over at least one tip of the tooth. By covering the tooth of the gear, it is prevented that dirt accumulates in the area of ​​the pre-fixing element between the pre-fixing element and the drive.

[0025] In one embodiment, it is particularly provided that at least three and at most five teeth of the drive gear are each secured by a pre-fixing element. Accordingly, at least three pre-fixing elements may be provided.

[0026] In particular, by means of exactly three pre-fixing elements or

[0027] Pre-fixing elements for three teeth precisely define the alignment of the driver, while making the mounting of the driver on the pre-fixing elements even easier.

[0028] It is preferably provided that at least one, and preferably all, of the possibly multiple pre-fixing elements are designed to be elastically deflectable. For this purpose, the pre-fixing element can, for example, be formed integrally with the housing part by means of an arm, so that the pre-fixing element is elastically movable via the (lever) arm.

[0029] Such an elastically deflectable design of the at least one pre-fixing element allows it to be easily deflected when the driver is attached, thus securely holding the driver in its orientation. Furthermore, the elastically deflectable pre-fixing element ensures that, at least in the force-limiting state of the first force-limiting device and during any associated rotation of the driver, its rotation is not impeded.

[0030] The at least one pre-fixing element is arranged and / or designed in such a way that the alignment of the driver is predetermined by the at least one pre-fixing element. In particular, the alignment of the driver teeth can be precisely determined by the at least one pre-fixing element. After the driver is mounted, the alignment of the teeth, and thus also the alignment of the gear coupled to the torsion bar, is therefore precisely determined.

[0031] Provided that the teeth of the driver are all identical, the driver is rotationally symmetrical with respect to its orientation, so that the driver can be arranged in equivalent orientations according to the number of teeth.

[0032] To align the drive element with the other components of the belt retractor, at least one tooth of the drive element's toothing, each associated with a pre-fixing element, may have a different design than the other teeth. For example, the tooth associated with a pre-fixing element may be at least partially flatter than the teeth not associated with any pre-fixing element. Accordingly, the pre-fixing element may be designed such that it can only hold a differently shaped tooth. For instance, a pre-fixing element designed to accommodate a flatter tooth may have a correspondingly low clearance height, ensuring that only teeth with a flatter design can be covered by the pre-fixing element.

[0033] Alternatively, it could also be provided that the teeth assigned to at least one pre-fixing element have a slightly smaller width (in the circumferential direction) and that the associated pre-fixing element can only pre-fix a narrower tooth accordingly.

[0034] In one embodiment, the at least one pre-fixing element may be designed such that the driver can be mounted into the position held by the at least one pre-fixing element by a linear movement along its axis of rotation. In this context, it may be provided, in particular, that the at least one pre-fixing element has a chamfer on its front surface against which the driver rests during assembly, preferably with the pre-fixing element being deflected radially during the linear movement of the driver during assembly. Preferably, all pre-fixing elements have a chamfer. During assembly, the driver is pressed onto the pre-fixing elements, particularly with the teeth provided for this purpose, so that the pre-fixing elements are deflected and, after reaching the assembly position, spring back into the position holding the pre-fixing elements.Spring-back is only possible if the corresponding teeth are aligned with their respective pre-fixing elements, ensuring the drive pin is correctly positioned. This makes assembly very simple.

[0035] In an alternative embodiment, the at least one pre-fixing element may be designed such that the driver can be mounted into the position held by the at least one pre-fixing element by a rotational movement about its axis of rotation. In this context, it may be provided, in particular, that the at least one pre-fixing element has a chamfer on one side against which the driver rests during assembly, preferably with the pre-fixing element being deflected radially during the rotational movement of the driver during assembly. In this context, it may also be provided, in particular, that the driver rests on projections at least during the rotational movement during assembly.In this embodiment, the driver, with its corresponding teeth, is first aligned in the direction of rotation relative to the pre-fixing elements and inserted into a corresponding housing part of the belt retractor. The driver is then rotated into the position in which it is held by the pre-fixing elements. To allow the driver to be easily rotated after insertion into the housing, projections, for example, can be provided on which the driver rotates. To ensure that the pre-fixing elements are reliably deflected when the driver is rotated, these projections can have chamfers arranged in the direction of rotation.

[0036] The invention and the technical context are explained below by way of example with reference to the figures. Figure 1 schematically shows an exploded view of a belt retractor with a first force limiting device.

[0037] Figure 2: an exploded view of the first force limiting device of Figure 1 with a torsion bar,

[0038] Figure 3: a sectional view through the belt retractor in the area of ​​the torsion bar,

[0039] Figure 4: a side view of the belt retractor,

[0040] Figure 5: a side perspective view of a housing part of the belt retractor with a pre-fixed driver in it, Figure 6: a detail view of a pre-fixing element for holding the driver,

[0041] Figure 7: a sectional view through the pre-fixing element and one tooth of the driver and

[0042] Figures 8a-8c: Assembly steps of another embodiment of a belt retractor.

[0043] Figure 1 shows an exploded view of a seatbelt retractor. The seatbelt retractor comprises a housing frame 11 and a belt shaft 1 rotatably mounted in the housing frame 11 for winding up a seatbelt (not shown). The seatbelt retractor includes a first force limiting device 2 and a second force limiting device 9, which is arranged in the belt shaft 1 and is, in particular, multi-stage. The second force limiting device 9 can be coupled on one side to a profile head that can be locked against the housing frame 11 and on the other side to the belt shaft 1.

[0044] Figure 2 shows the first force limiting device 2 of the belt retractor from Figure 1 in detail. The first force limiting device 2 has a torsion bar 3 as a force limiting element and a driver 4. The driver 4 has a toothed section 16 with teeth on its outer circumference. The torsion bar 3 has a gear 12 at one end, which is driven by the driver 4 in the force-limiting state of the first force limiting device 2.

[0045] As can be seen from the sectional view in Figure 3, the torsion bar 3 is non-rotatably connected at its other end to the housing frame 11. The gear 12 is crimped to the torsion bar 3 in the region of the other end of the torsion bar 3. The torsion bar 3 is inserted through the housing frame 11 and a housing part 13 for receiving the first force limiting device 2 and a release device 8 on the side of the gear 14 facing the fixed end, and is rotatably mounted in a cover 16 at a projection on the side of the gear 14 facing away from the fixed end.

[0046] The first force limiting device 2 also includes a coupling element 5, which is rotationally fixed to the belt shaft 1 (see Figures 2 and 4). The coupling element 5 has chamfers on its outer circumference.

[0047] The first force limiting device 2 also comprises a wheel element 7 and a locking unit 6 (see Figure 2). The locking unit 6 has an approximately circular bearing section to which inwardly extending arms are attached. Locking elements 6.1 are formed at the free ends of each arm. The bearing section and the arms define a plane from which the locking elements 6.1 protrude (obliquely rearward in Figure 2). The wheel element 7 has first predetermined breaking features in a central area, by means of which the wheel element 7 is at least indirectly rotationally fixed to the belt shaft 1 in an initial state. The wheel element 7 has a tooth-like shape on its outer circumference and is cup-shaped between the outer circumference and the inner receptacle with the first predetermined breaking features. In the assembled state, the locking unit 6 is arranged in this cup-shaped receptacle, with the locking elements 6.1. The locking unit 6 protrudes section by section beyond the mounting. The locking unit 6 is initially fixed in the wheel element 7 in a rotationally fixed manner by means of two predetermined breaking features.

[0048] In the assembled state, the locking elements 6.1, which protrude beyond the mounting of the wheel element 7, are arranged between the coupling element 5 and the driver 4. Each locking element 6.1 is associated with a chamfer on the coupling element 5.

[0049] In the initial state of the first force limiting device 2, the wheel element 7 is connected to the belt shaft 1 by means of the first predetermined breaking design, so that the locking unit 6, which is connected to the wheel element 7 via the second predetermined breaking design, also rotates with the belt shaft 1.

[0050] In contrast, the driver 4 and the torsion bar 3 connected to the driver 4 are fixedly arranged in the housing 10 in the initial state. By triggering the release device 8, the relative rotation of the wheel element 7 can be stopped by engaging a locking element 8.1 with the tooth design on the outer circumference of the wheel element 7.

[0051] As the belt shaft 1 continues to rotate relative to the fixed wheel element 7, the connection between the wheel element 7 and the belt shaft 1 is destroyed at the first predetermined breaking point 7.1. The belt shaft 1, and therefore also the coupling element 5, continues to rotate relative to the fixed wheel element 7 and the locking unit 6 fixed together with the wheel element 7.

[0052] The relative rotation of the coupling element 5 with respect to the radially deflectable locking elements 6.1 causes a relative movement of the locking elements 6.1 along the approach ramps of the coupling element 5. This deflects the locking elements 6.1 radially outwards until they engage with the driver 4. The locking elements 6.1 thus establish a rotationally fixed connection between the coupling element 5 and the driver 4, so that with continued rotation of the belt shaft 1 and the coupling element 5, the driver 4 is also driven into a rotary motion.

[0053] Subsequently, the locking unit 6 also rotates with the driver 4 and the coupling element 5, thereby destroying the connection of the locking unit 6 with the wheel element 7 at the second predetermined breaking point 7.2, so that the locking unit 6 subsequently rotates relative to the fixed wheel element 7.

[0054] At the same time, the rotational movement of the driver 4 causes a deformation of the torsion bar 3, which absorbs energy and thus provides a force limiting level for the relative rotation of the belt shaft 1.

[0055] The coupling of the driver 4 with the gear 12 can also be seen in the side view of Figure 4, according to which the teeth of the gear 14 engage in the teeth 16 on the outer circumference of the driver 4. In the force-limiting state of the first force-limiting device 2, the driver 4 rotates with the belt shaft 1, thereby driving the gear 14 and thus twisting the torsion bar 3.

[0056] Figure 5 shows the driver 4 already inserted into the housing part 13. The housing part 13 forms three pre-fixing elements 15.1, 15.2, and 15.3, of which pre-fixing elements 15.1 and 15.2 are deflectable in the radial direction, while pre-fixing element 15.3 is designed as a receptacle. Each pre-fixing element 15.1, 15.2, and 15.3 is associated with a tooth 17.1, 17.2, and 17.3 of the driver 4, which are geometrically different from the other teeth 17.4 of the driver 4.

[0057] The detailed views in Figures 6 and 7 show that the teeth 17.1, 17.2 and 17.3 associated with the fixing elements 15.1, 15.2 and 15.3 are flatter at their radial ends than the other teeth 17.4. Accordingly, the clear height of the fixing elements 15.1, 15.2 and 15.3, which accommodates the radial ends of the teeth 17.1, 17.2 and 17.3, is designed such that only the correspondingly shaped teeth 17.1, 17.2 and 17.3, and not the other teeth 17.4, can be accommodated.

[0058] Figure 6 also shows that the pre-fixing element 15.1 is arranged at one end of a deflectable arm. On its visible upper surface, the pre-fixing element 15.1 has a chamfer 18.1, which allows the driver 4 to be pressed onto the pre-fixing element 15.1 from above, causing it to deflect radially and return to the position shown in Figure 6. In the force-limiting state of the first force-limiting device 2, the tooth 17.1 can move circumferentially because the pre-fixing element 15.1 is deflected radially when a corresponding force is applied.

[0059] Since the pre-fixing element 15.3 shown in Figure 5 is not radially deflectable, the associated tooth 17.3 can first be inserted into the pre-fixing element 15.3 and the driver 4 can be pressed onto the two remaining pre-fixing elements 15.1 and 15.2. The pre-fixing element 15.3 is also designed such that the driver 4 can rotate in the force-limiting state of the first force-limiting device 2.

[0060] As can be seen particularly from the illustration in Figure 4, the pre-fixing elements 15.1, 15.2 and 15.3 define an orientation of the driver 4, so that, on the one hand, the gear 12, which is coupled to the torsion bar 3, can be mounted in an orientation defined by the orientation of the driver 4. At the same time, it is ensured that the driver 4 is aligned in a desired orientation relative to the coupling element 5, so that the locking unit 6 with the locking elements 6.1 can be mounted in a predetermined manner.

[0061] Figures 8a to 8c show the assembly process of another embodiment of a belt retractor. This differs from the previously described belt retractor primarily in the specific design of the pre-fixing elements 15.1 to 15.3. The pre-fixing elements 15.1 to 15.3 do not have a chamfer on their upper surface. Instead, each pre-fixing element 15.1 to 15.3 has a chamfer 18.2, which is aligned in the direction of rotation of the driver 4. To mount the driver 4, it is first placed onto projections 18 on a housing part of the belt retractor, with the teeth 17.1 to 17.3 to be held being offset in the direction of rotation relative to the axis of rotation of the driver 4 from the corresponding pre-fixing elements 15.1 to 15.3 (see Figures 8a and 8b). From the intermediate position shown in Figure 8b during assembly, the driver 4 is rotated in the direction of rotation so that the teeth 17.1 to 17.3 into the position held by the associated pre-fixing elements 15.1 to 15.3.

[0062] The pre-fixing elements 15.1, 15.2 and 15.3 simplify the assembly of the belt retractor and prevent assembly errors. Reference list

[0063] belt shaft

[0064]

[0065] First force limiting device 2

[0066] Torsion bar 3

[0067] Driver 4 Coupling element 5

[0068] Locking unit 6

[0069] Locking element 6.1

[0070] Wheel element 7 Release device 8 Locking element 8.1

[0071] Second force limiting device 9

[0072] Housing 10 Housing frame 11

[0073] Gear 12

[0074] Housing part 13

[0075] Cover 14 Pre-fixing element 15.1, 15.2, 15.3 Toothing 16

[0076] Tooth 17.1, 17.2, 17.3, 17.4 Lead-in chamfer 18.1, 18.2 Projection 19

Claims

Claims 1. Belt retractor for a motor vehicle seat belt, with a belt shaft (1) rotatably mounted about an axis of rotation in a housing frame (11), at least one first force limiting device (2), wherein the first force limiting device (2) • at least one torsion bar (3) arranged outside the belt shaft (1) and • comprising a driver (4) connected to the at least one torsion bar (3), wherein the at least one torsion bar (3) is coupled to the driver (4) in particular at a first end by means of a gear (12) and at its other end is fixed against rotation relative to the housing frame (11) and the driver (4) has a toothing (16) on its outer circumference, characterized by the fact that the belt retractor has at least one pre-fixing element (15.1, 15.2, 15.3), wherein the driver (4) is held by the at least one pre-fixing element (15.1, 15.2, 15.3).

2. Belt retractor according to claim 1, wherein at least one pre-fixing element (15.1, 15.2, 15.3) is elastically deflectable.

3. Belt retractor according to any of the preceding claims, wherein a pre-fixing element (15.1, 15.2, 15.3) covers and / or receives a tooth (17.1, 17.2, 17.3) of the toothing (16) of the driver (4).

4. Belt retractor according to any of the preceding claims, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) predefines an orientation of the driver (4).

5. Belt retractor according to one of the preceding claims, wherein a tooth (17.1, 17.2, 17.3) of the toothing (16) of the driver (4), which is associated with a pre-fixing element (15.1, 15.2, 15.3), has a different design than the other teeth (17.4) of the toothing (16).

6. Belt retractor according to claim 5, wherein the tooth (17.1, 17.2, 17.3) associated with a pre-fixing element (15.1, 15.2, 15.3) is at least partially flatter than the teeth (17.4) not associated with any pre-fixing element (15.1, 15.2, 15.3).

7. Belt retractor according to claim 5 or 6, wherein the pre-fixing element (15.1, 15.2, 15.3) is designed such that the pre-fixing element (15.1, 15.2, 15.3) can exclusively hold a differently shaped tooth (17.1, 17.2, 17.3).

8. Belt retractor according to one of the preceding claims, wherein three to five pre-fixing elements (15.1, 15.2, 15.3) are provided.

9. Belt retractor according to one of the preceding claims, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) is formed integrally with a housing part (13) of the belt retractor.

10. Belt retractor according to one of the preceding claims, wherein the first force limiting device (2) is a coupling element (5) rotating with the belt shaft (1) and • comprising a locking unit (6) comprising at least one locking element (6.1), wherein in a force-limiting state of the first force-limiting device (2) • the driver (4) is connected to the coupling element (5) in a rotationally fixed manner via the at least one locking element (6.1), so that the driver (4) rotates with the belt shaft (1), and • the at least one force limiting element (3) is fixed at one end against rotation with the belt shaft (1) and is deformed due to the rotational movement of the driver (4), wherein the torsion bar (3) is deformed in the force-limiting state of the first force-limiting device (2) by the rotation of the belt shaft (1).

11. Belt retractor according to claim 10, wherein the at least one locking element (6.1) is radially deflectable to bring about the force-limiting state by a relative movement between the coupling element (5) and the driver (4), wherein the at least one locking element (6.1) in a deflected position connects the driver (4) to the coupling element (5) in a rotationally fixed manner.

12. Belt retractor according to one of the preceding claims, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) is designed such that the driver (4) can be mounted into the position held by the at least one pre-fixing element (15.1, 15.2, 15.3) by a straight-line movement along its axis of rotation.

13. Belt retractor according to claim 12, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) has a chamfer (18.1) on its front side against which the driver (4) rests during assembly, wherein preferably the pre-fixing element (15.1, 15.2, 15.3) is deflected in a radial direction during the linear movement of the driver (4) during assembly.

14. Belt retractor according to one of the preceding claims, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) is designed such that the driver (4) can be mounted into the position held by the pre-fixing element (15.1, 15.2, 15.3) by a rotational movement about its axis of rotation.

15. Belt retractor according to claim 14, wherein the at least one pre-fixing element (15.1, 15.2, 15.3) has a chamfer (18.2) on one side against which the driver (4) rests during assembly, wherein preferably the pre-fixing element (15.1, 15.2, 15.3) is deflected in a radial direction during the rotational movement of the driver (4) during assembly.

16. Belt retractor according to claim 14 or 15, wherein the driver (4) rests on projections (19) at least during the rotational movement during assembly.

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