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DE-102024136149-B3 - seatbelt retractor

DE102024136149B3DE 102024136149 B3DE102024136149 B3DE 102024136149B3DE-102024136149-B3

Abstract

The invention relates to a belt retractor (1) comprising a belt spool (2) rotatably mounted in a frame, and a profile head (5) that can be locked to the vehicle via a first locking device (7), and a force limiting device (4) arranged between the belt spool (29) and the profile head (5) with at least one first torsion bar (8) having a high plastic deformation limit and a second torsion bar (9) with a lower plastic deformation limit, wherein the belt spool (2) has a first tubular extension (11) arranged on an end face of the belt spool (2), and the profile head (5) has a second tubular extension (12) arranged on an end face of the profile head (5), wherein a threaded bushing (13) is provided which is guided non-rotatably and axially displaceably on the second extension (12) of the profile head (5), which engages with the torque tube (10) via a threaded drive and is activated by the second torsion bar (9) performs a linear displacement movement relative to the torque tube (10) and relative to the second forging set (12), and a stop is provided to limit the linear displacement movement of the threaded bushing (13), and the threaded bushing (13) in the contact position against the stop forms a rotationally fixed connection of the second forging set (12) with the torque tube (10).

Inventors

  • Jens Ehlers
  • Hans-Jörg Langhoff

Assignees

  • AUTOLIV DEVELOPMENT AB

Dates

Publication Date
20260513
Application Date
20241204

Claims (6)

  1. A seatbelt retractor (1) comprising: - a belt spool (2) rotatably mounted in a frame (3), and - a profile head (5) which can be locked to the vehicle via a first locking device (7), and - a force limiting device (4) arranged between the belt spool (2) and the profile head (5) with at least one first torsion bar (8) having a high plastic deformation limit and a second torsion bar (9) having a lower plastic deformation limit than the first torsion bar (8), wherein - the belt spool (2) has a first tubular extension (11) arranged on an end face of the belt spool (2), and - the profile head (5) has a second tubular extension (12) arranged on an end face of the profile head (5), wherein - the first torsion bar (8) is arranged in a radially inner cavity of the first extension (11) and the second torsion bar is arranged in a radially inner cavity of the second extension (12), and - a torque tube (10) connected to the first extension (11) in a rotationally fixed manner via a second switchable locking device (16), wherein - the first torsion bar (8) has a first end (25) connected to the belt spool (2) in a rotationally fixed manner and a second end (26) connected to the torque tube (10), and - the second torsion bar (9) has a first end (27) connected to the torque tube (10) in a rotationally fixed manner and a second end (28) connected to the profile head (5) in a rotationally fixed manner, characterized in that - a threaded bushing (13) is provided which is guided in a rotationally fixed and axially displaceable manner on the second extension (12) of the profile head (5), which engages with the torque tube (10) via a threaded drive and, when the second torsion bar (9) is activated, performs a linear displacement movement relative to the torque tube (10) and relative to the second extension (12), and - a linear A stop is provided to limit the displacement movement of the threaded bushing (13), and the threaded bushing (13) in the contact position against the stop forms a rotationally fixed connection of the second extension (12) with the torque tube (10).
  2. seatbelt retractor (1) after Claim 1 , characterized in that -the stop is arranged directly on the torque tube (10).
  3. seatbelt retractor (1) after Claim 2 , characterized in that -the threaded bushing (13) is formed by a ring which encompasses the torque tube (10), and -the ring has a radially inwardly projecting collar (29) arranged at one end, and -the stop is formed by an end face (18) of the torque tube (10) against which the threaded bushing (13) comes to rest with the collar (29) during the displacement movement.
  4. seatbelt retractor (1) after Claim 1 , characterized in that -the stop is formed indirectly by a part which is supported on the torque tube (10).
  5. belt retractor (1) after one of the Claims 1 until 4 , characterized in that -the second switchable blocking device (16) by The torque acting between the belt spool (2) and the torque tube (10), which increases in the stop position of the threaded bushing (13), can be switched.
  6. belt retractor (1) after one of the Claims 1 until 5 , characterized in that the threaded bushing (13) is connected to the torque tube (10) in a rotationally fixed manner at least in the contact position against the stop via a positive locking design.

Description

The present invention relates to a belt retractor having the features of the preamble of claim 1. Seatbelt retractors consist of a load-bearing frame and a belt spool rotatably mounted within the frame, onto which a seatbelt can be wound. Besides supporting the belt spool, the frame also serves to attach the retractor to a seat structure or vehicle body and is therefore made of a sufficiently thick sheet of steel bent into a U-shape. Furthermore, modern seatbelt retractors are equipped with force-limiting devices to reduce occupant stress. In an accident, these devices allow for a force-limited extension of the seatbelt until the occupant is, for example, restrained by an airbag. Plastically deformable torsion bars have proven effective for this purpose. One end of these bars is rotationally fixed to the belt reel, while the other end is connected to a section (profile head) that can be locked to the vehicle in an accident via a first locking mechanism. The force-limiting level of the belt extension achieved by such a device is defined by the plastic deformation limit of the torsion bar. From the printed text DE 199 27 427 A1 A belt retractor is known which has a two-stage torsion bar with two torsion sections having different plastic deformation limits, separated from each other by a central profiled section. The two-stage torsion bar is non-rotatably connected to the profiled head at its free end, which forms the end of the torsion section with the higher force limiting level. The other free end is non-rotatably connected to the belt spool. Furthermore, a switchable second locking device with a torque tube is provided, wherein the torque tube is connected to a profile of the torsion bar in the profiled central section. The switchable second locking device also includes two releasable locking pawls that lock the torque tube relative to the frame of the belt retractor. This means that the torsional section with the lower plastic deformation limit, and thus the lower force limitation level, is bridged at the beginning of the force-limited belt extension. The force-limited belt extension is then enabled at the beginning of the force limitation phase by plastic deformation of the torsional section with the higher plastic deformation limit, resulting in a higher force limitation level. When the second locking device is activated, the locking of the torque tube is released, and further force-limited belt extension is enabled by plastic deformation of the torsional section with the lower plastic deformation limit, again at the lower force limitation level. The two-stage torsion bar, together with the torque tube, is arranged in a cavity of the belt spool, necessitating a belt spool with a correspondingly large cavity and outer diameter. Furthermore, it is known to equip seat belt retractors with force-limiting devices featuring a progressive force-limiting curve, i.e., with a continuously or gradually increasing force-limiting level, if the occupant is to be restrained with an increasing restraint force. Such seat belt retractors are used by some vehicle manufacturers to restrain occupants in the rear seats. Furthermore, it is known to equip vehicle seats with integrated seat belt systems, in which at least the belt retractors of the seat belt systems are mounted in the backrests of the vehicle seats. In this case, due to the lack of a load-bearing B-pillar and for reasons of access to the rear seats or distance from the rear vehicle structure, the belt retractors are preferably integrated into the backrests of the vehicle seats, which must therefore also be designed to absorb the tensile forces acting in the event of a restraint. The belt retractors themselves have all the basic components of a standard belt retractor and are only equipped with various additional assemblies specifically designed for installation in the backrest, such as a self-aligning inertial sensor. Installation in the backrests is problematic because the available installation space is very small, and the backrests cannot be arbitrarily enlarged or their basic structure modified for this purpose. The structure of the backrests is designed specifically to absorb the restraining forces in the event of an accident, using a truss of struts which are intended to form the stiffest possible structure with the lowest possible weight. From the printed text DE 10 2020 211 209 A1 A belt retractor is known which can be attached, for example, to a backrest and has a very compact, and in particular slim, design, in that the torsion bars, the belt shaft, and the profile head are arranged coaxially and in series with one another. Furthermore, axially projecting annular extensions are provided on the belt spool and the profile head at their facing end faces, into which the torsion bars extend. Furthermore, profiled receptacles are provided for the extensions, in which the torsion bars are fixed at one end in a rotationally fixed manner. Furthermore, the prin