GURTAUFROLLER

Description

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

[0002] 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.

[0003] 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 device. The force-limiting level of the belt extension is determined by the plastic deformation limit of such a torsion bar.

[0004] German patent application DE 199 27 427 A1 discloses a belt retractor comprising a two-stage torsion bar with two torsion sections exhibiting different plastic deformation limits. The free end of the two-stage torsion bar, which forms the end of the torsion section with the higher force limiting level, is non-rotatably connected to the profile head. 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 in a profiled central section to a profile of the torsion bar, which separates the two torsion sections. 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 by plastic deformation of the torsional section with the higher plastic deformation limit at 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 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, which necessitates a belt spool with a correspondingly large cavity and outer diameter.

[0005] 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.The integration into the backrests is problematic because the available installation space is very small, and the backrests cannot be arbitrarily enlarged or their basic structure arbitrarily modified for this purpose. The structure of the backrests, in particular to absorb the restraining forces in an accident, is designed with a truss of struts, which are intended to form the stiffest possible structure with the lowest possible weight. This requirement inevitably results in a structure that can only be modified to a limited extent, with long, preferably continuous struts that divide the interior of the backrest into several elongated spaces. DE102018213282A discloses a seatbelt retractor according to the preamble of claim 1.

[0006] This presents a problem for seatbelt retractors, especially when they are intended for installation in backrests, as they must be designed to be as compact as possible and, in particular, suitable for installation in very narrow and elongated spaces.

[0007] To solve the problem, a belt retractor with the features of claim 1 is proposed. Further preferred embodiments can be found in the dependent claims, the figures, and the accompanying description.

[0008] According to the basic idea of ​​the invention, it is proposed that the belt spool, the first torsion bar and the profile head are arranged coaxially and in series with each other.

[0009] The proposed solution allows for a more elongated, narrow basic design of the belt retractor. In contrast to the prior art, the first torsion bar is relocated outside the belt spool and arranged coaxially to it. This allows the belt spool to have a smaller outer diameter, as the previously required cavity within the spool for the torsion bar is eliminated. Furthermore, the profile head, which can be locked to the vehicle via the first locking device, is also arranged coaxially and in series with the belt spool, thus separating it from the spool. This further reduces the size of the belt spool, as the profile head is no longer directly attached to it.Furthermore, the coaxial arrangement of the three basic components allows for a very narrow and elongated design of the seatbelt retractor, making it easier to install in existing narrow and elongated spaces in the seatback or vehicle structure. If the existing space is insufficient, it can be slightly modified and adapted.

[0010] The first torsion bar is preferably arranged in series between the belt reel and the profile head. This first torsion bar effectively forms the connection between the profile head and the belt reel. If the profile head becomes blocked, the second end of the first torsion bar is also blocked, and the first end of the first torsion bar, along with the belt reel, can rotate relative to the blocked profile head. This rotation is caused by plastic deformation of the section of the first torsion bar located between its first and second ends. This results in a simple and clear basic design with the most direct force flow possible, allowing the belt retractor to be designed very compactly to withstand the required restraint forces.

[0011] It is further proposed that the profile head and the belt spool be mounted at an axial distance from each other in separate radial bearings. In the previous arrangement of the profile head on the belt spool, it simultaneously formed the radial bearing of the belt spool, whereby the arrangement of the torsion bar and the radial bearing of the belt spool in the profile head resulted in a comparatively large outer diameter of the belt spool.

[0012] The proposed separate radial bearing arrangement allows for a simpler and therefore more space-efficient mounting of the belt spool. Furthermore, the two bearings and the axial spacing of the radial bearings result in a more stable overall mounting.

[0013] The first torsion bar is held in a rotationally fixed position at its first end within a receptacle on the belt reel that is open towards the axial outside. The first torsion bar is thus rotationally fixed at its first end on the outside of the belt reel and extends coaxially outwards from the receptacle in the axial direction from the belt reel.

[0014] At least one second torsion bar is arranged coaxially and in series with the belt spool, between the first torsion bar and the profile head. By providing the second torsion bar, a higher or lower force limitation level of the force-limited belt extension can be achieved, depending on the type of activation.

[0015] The second and first torsion bars have different plastic deformation limits, so that a step-like progression of the force limitation characteristic can be achieved by successively activating the two torsion bars.

[0016] A torque tube is provided, which is fixed against rotation relative to the belt spool by means of a switchable second locking device. The torque tube connects the two opposing ends of the first torsion bar and the second torsion bar in a rotationally fixed manner. The torque tube allows the first torsion bar to be deliberately bypassed to activate the second torsion bar in the first phase of force limitation. The first torsion bar is then activated by switching the second locking device.

[0017] An axially projecting extension is provided on the belt spool, against which the torque tube is secured via the switchable second locking device. This axially projecting extension creates a force transmission surface on the belt spool, against which the torque tube is supported. Due to the arrangement of the extension, this force transmission surface is created without increasing the outer diameter of the belt spool, and the coaxial arrangement of the torsion bars in series with the belt spool can be implemented with particular ease.

[0018] The axial extension is preferably annular in shape, and the torque tube can project radially inward into the axial annular extension or encompass the axial annular extension radially outward. This provides the torque tube with additional radial support and, in particular, after the second locking device has been engaged and disengaged during the execution of the rotary movement, it is radially supported by the extension.

[0019] It is further proposed that an axially projecting annular extension be provided on the profile head, and that the torque tube either projects radially inward into the annular extension or encompasses the annular extension radially outward. The proposed solution is advantageous because the torque tube is supported on the profile head via the annular extension and is mounted on the profile head during relative rotational movement. This is particularly advantageous due to the increased axial length of the belt winder resulting from the solution according to the invention.

[0020] It is further proposed that the belt spool be designed as a solid shaft. This solid shaft design allows for a particularly compact construction while simultaneously providing very high rigidity to the belt spool. For example, appropriate positive-locking features can be incorporated into the belt spool for coupling the belt; in any case, the cavity previously required for the torsion bar can be eliminated. Furthermore, the solid shaft design of the belt spool makes it particularly easy to implement the axial mounting for the rotationally fixed fixing of the first end of the first torsion bar.

[0021] The invention is explained below with reference to preferred embodiments and the accompanying figures. Fig. 1 shows a belt retractor with various additional assemblies in sectional view, and Fig. 2 shows the belt retractor with the force limiting device.

[0022] In theFigure 1The diagram shows a seatbelt retractor with a belt spool 1 rotatably mounted in a frame 8, which is equipped with various additional components. These include a force limiting device 2, an electric motor 5, a gearbox 4, and an irreversible pyrotechnic tensioning device 19. The seatbelt retractor, together with the frame 8 and the belt spool 1 mounted therein, as well as the other additional components, is held in a larger housing 20. The housing 20 also serves to mount the seatbelt retractor in the backrest of a vehicle seat or in an elongated installation space within a vehicle structure. The electric motor 5 is used for reversible belt tensioning and various other comfort functions, such as a retraction aid, spring adjustment, or seatbelt warning.The drive rotary motion of the electric motor 5 is translated via the gearbox 4 and transferred via a transfer rod 6 to the force limiting device 2, which in turn drives the belt spool 1.

[0023] In the Figure 2 The belt retractor with the belt spool 1 and the force limiting device 2 is shown enlarged. The frame 8 is supported by the housing 20, which, in the position attached to the vehicle or seat, forms a vehicle-fixed abutment for the frame 8. The force limiting device 2 is arranged on the end face of the belt spool 1 in an orientation coaxial with the axis of rotation of the belt spool 1 and is connected to the belt spool 1.

[0024] The force limiting device 2 comprises a first torsion bar 9, a second torsion bar 10, a profile head 7, and a second switchable locking device 3. The profile head 7 carries a locking pawl (not shown), which forms a first locking device and blocks the profile head 7 in the extension direction of a seat belt (also not shown) wound on the belt reel 1 when activated by a belt extension acceleration-sensitive sensor device and / or a vehicle acceleration-sensitive sensor device. The belt reel 1 is rotatably mounted in the frame 8, which in turn is fixedly fixed in the housing 20 and can be attached to the vehicle or the seat back via this frame. The profile head 7 is radially mounted at axial distances in a web 22 fixed in the housing 20.This means that, in a departure from the previously used basic principle, the belt spool 1 and the profile head 7 are mounted independently of each other and axially spaced apart. Thus, the belt spool 1 in the frame 8 and the profile head 7 in the web 22 each have separate and axially spaced radial bearings. This allows the assembly consisting of the belt spool 1 and the force limiting device 2 to be mounted more stably overall, which is particularly advantageous during the activation of the force limiting device 2.

[0025] The belt spool 1 has a profiled receptacle 15, which is open axially towards the outside. The first torsion bar 9 is fixedly fixed at its first end 11 in the receptacle 15 and has an outer profile corresponding to the profile of the receptacle 15. The receptacle 15 is encompassed by an annular extension 17 extending axially away from the end face of the belt spool 1. A torque tube 16 is also provided, which engages in the extension 17 and encompasses the first torsion bar 9. The torque tube 16 is connected to the extension 17 via the switchable second locking device 3 by means of two locking pawls, the release of which is carried out according to the switching principle described in DE 199 27 427 A1.

[0026] The torque tube 16 simultaneously serves as a rotationally fixed connection between the second profiled end 12 of the first torsion bar 9 and the first profiled end 13 of the second torsion bar 10. For this purpose, the torque tube 16 has a central section with radially inwardly directed projections with which it engages in external profiles of the second end 12 of the first torsion bar 9 and the first end 13 of the second torsion bar 10, thereby connecting both ends to each other in a rotationally fixed manner.

[0027] The profile head 7 also has a central profiled receptacle 18, which is encompassed by an axially extending annular extension 21. The second end 14 of the second torsion bar 10 is provided with an outer profile corresponding to the profile of the receptacle 18 and is thereby fixed in the receptacle 18 relative to the profile head 7 in a rotationally fixed manner. Furthermore, the torque tube 16 encompasses the annular extension 21 radially on the outside and is supported by the profile head 7. Since the profile head 7 is itself mounted separately from the belt spool 1, it forms a frame-fixed abutment for the torque tube 16.

[0028] To activate the force limiting device 2, the profile head 7 is first locked to the vehicle via the first locking device when a predetermined belt extension acceleration or vehicle deceleration is exceeded, whereby the exceeding of the predetermined limit values ​​is detected by means of the sensor devices described above.

[0029] If the occupant moves forward due to inertia during an accident, the seat belt is extended, and the restraining force, i.e., the tensile force in the seat belt, increases. This causes the belt spool 1 to rotate in the extension direction of the seat belt until further rotation is blocked by the locking mechanism of the profile head 7. Subsequent extension of the belt is only possible if it is enabled by plastic deformation of the two torsion bars 9 and 10.

[0030] Before the second locking device 3 is engaged, the torque tube 16 is rotationally fixed to the belt spool 1, the extension 17, the second end 12 of the first torsion bar 9, and the first end 13 of the second torsion bar 10, thus disengaging the first torsion bar 9 from the force flow. During this phase, the second torsion bar 10 is plastically deformed about its longitudinal axis if the pull-out force of the seat belt exceeds the pull-out force defined by the force-limiting level of the second torsion bar 10. The second torsion bar 10 has a higher force-limiting level than the first torsion bar 9, resulting in a high force-limiting level during this phase. In this case, the torque tube 16 rotates relative to the locked profile head 7 and is supported on the annular extension 21 of the profile head 7.

[0031] By activating the second locking device 3, the connection between the torque tube 16 and the extension 17 is released. The first torsion bar 9 is then subjected to the force flow. Since the first torsion bar 9 has a lower force limiting level than the second torsion bar 10, the second torsion bar 10 acts as a fixed bearing, and the second end 12 of the first torsion bar 9 is also blocked due to its connection with the first end 13 of the second torsion bar 10 via the torque tube 16. As a result, the first end 11 of the first torsion bar 9 rotates relative to the blocked second end 12, and the first torsion bar 9 is plastically deformed about its longitudinal axis. The lower force limiting level now applies.In this case, the torque tube 16 is blocked by the positive-locking connection with the first end 13 of the second torsion bar 10, and the belt spool 1 rotates relative to the torque tube 16, and the extension 17 of the belt spool 1 additionally forms a bearing for the torque tube 16.

[0032] The invention is described with reference to a force limiting device 2 with two torsion bars 9 and 10, which enable a stepped force limiting profile. The two torsion bars 9 and 10 are arranged coaxially and in series, so that their arrangement does not increase the outer diameter. The belt retractor is only made slightly longer as a result.

Claims

1. Belt retractor comprising - a belt reel (1) rotatably mounted in a frame, and - a force-limiting device (2) having at least one plastically deformable first torsion rod (9), - the first torsion rod (9) having a first end (11) rotationally fixed to the belt reel (1) and a second end (12) rotationally fixed to a profiled head (7) which can be blocked via a first blocking device in a fixed manner relative to the vehicle, - the belt reel (1), the first torsion rod (9) and the profiled head (7) being arranged coaxially to one another and in series relative to one another, - the first torsion rod (9) being held in a rotationally fixed manner with the first end (11) in a receptacle (15) of the belt reel (1) that is open toward the axial outer side, - at least one second torsion rod (10) being arranged coaxially and in series with the belt reel (1) between the first torsion rod (9) and the profiled head (7), - the second and the first torsion rod (9,10) having different plastic deformation limits, characterized in that - a torque tube (16) is provided which is fixed in relation to the belt reel (1) in a rotationally fixed manner via a switchable second blocking device (3), - the torque tube (16) connecting the two mutually facing ends (12,13) of the first torsion rod (9) and the second torsion rod (10) to one another in a rotationally fixed manner, and - an axially projecting protrusion (17) being provided on the belt reel (1), in relation to which the torque tube (16) is fixed via the switchable second blocking device (3), and - the axial protrusion (17) being annular, and - the torque tube (16) projecting radially inwardly into annular protrusion (21) or surrounding the annular protrusion (21) radially on the outside.

2. Belt retractor according to claim 1, characterized in that - the first torsion rod (9) is arranged in series between the belt reel (1) and the profiled head (7).

3. Belt retractor according to claim 2, characterized in that - the profiled head (7) and the belt reel (1) are mounted at an axial distance from one another in separate radial bearings.

4. Belt retractor according to any of claims 1 to 3, characterized in that - an axially projecting annular protrusion (21) is provided on the profiled head (7), and - the torque tube (16) projects radially inwardly into the annular protrusion (21) or surrounds the annular protrusion (21) radially on the outside.

5. Belt retractor according to any of claims 1 to 4, characterized in that - the belt reel (1) is designed as a solid shaft.