Gurtaufroller

Abstract

The invention relates to a seatbelt retractor (1) comprising a belt spool (2) rotatably mounted in a frame, and a force limiting device (4) with at least one plastically deformable first torsion bar (8), wherein the first torsion bar (8) has a first end (25) rotationally fixed to the belt spool (2) and a second end (26) rotationally fixed to a profile head (5) that can be locked to the vehicle via a first locking device (7), 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 / or the second extension (12), and wherein a threaded bushing (13) is provided which is connected to one of the extensions (11,12) is in a threaded engagement and is axially displaceable and rotationally fixed to the other extension (11,12), and a stop is provided which blocks the axial displacement movement of the threaded bushing (13) in a stop position and thus limits a further rotational movement of the belt spool (2) relative to the profile head (5).

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 mechanism. The force-limiting level of the belt extension achieved by such a force-limiting device is defined by the plastic deformation limit of the 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, separated by a central profiled section. 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 profiled 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, the torque tube being 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 within the belt spool, necessitating 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.Integrating the system into the backrests is problematic because the available installation space is very small, and the backrests cannot be arbitrarily enlarged or their basic structure modified to accommodate the installation. The backrest structure is specifically designed to absorb the restraining forces in an accident, featuring a truss of struts intended to provide the stiffest possible structure with the lowest possible weight.

[0006] From German patent application 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 each other. Furthermore, axially projecting annular extensions are provided on the facing end faces of the belt spool and the profile head, into which the torsion bars extend. Profiled receptacles are also provided in the annular extensions in which the torsion bars are fixed at one end to prevent rotation.

[0007] To meet specified test or customer requirements, it may be necessary, particularly for the seat belt systems provided on the rear seats, that the force-limited belt extension made possible by the torsion bars is limited by a stop.

[0008] Against this background, the invention is based on the objective of providing a belt retractor with a force limiting device with a stop function in the most compact design possible.

[0009] To solve the problem, a belt retractor with the features of claim 1 is proposed. Further preferred developments can be found in the dependent claims, the figures, and the accompanying description.

[0010] According to the basic concept of the invention, it is proposed that a threaded bushing be provided which engages one of the extensions in a threaded connection and is axially displaceable and rotationally fixed to the other extension, and that a stop be provided which blocks the axial displacement of the threaded bushing in a stop position and limits further rotation of the belt spool relative to the profile head. The threaded bushing connects the belt spool and the profile head by bridging the first torsion bar. The first extension can rotate relative to the second extension, i.e., the belt spool relative to the profile head, through the threaded connection of the threaded bushing. This rotation is converted by the thread pitch into an axial displacement of the threaded bushing and is enforced by the rotationally fixed connection of the threaded bushing to the other extension.According to the invention, this sliding movement is then limited by the stop, which in turn is a prerequisite for the rotational movement of the belt spool. Thus, from the moment the threaded bushing contacts the stop and the sliding movement is blocked, the rotational movement of the belt spool is also blocked. The extensions serve to create a cavity for receiving the first torsion bar. Furthermore, the extensions form an extension of the belt spool and the profile head relative to each other, allowing them to be connected more easily via the threaded bushing.

[0011] It is further proposed that the stop be associated with the extension that engages the threaded bushing. During the force-limited extension of the belt spool, the threaded bushing undergoes an axial displacement due to the thread engagement, a displacement caused and defined by the thread pitch. This makes it structurally simple to limit this displacement by means of a stop that is also associated with the extension containing the thread—that is, the part that defines and initiates the displacement. Thus, the extension, through the thread dimensions and the stop provided thereon, defines both the path of the displacement and its endpoint.

[0012] The stop can be located directly on the extension, for example by means of a corresponding shape design of the extension itself.

[0013] Alternatively, the stop can also be formed indirectly by a component that rests against the extension, and this component can also have additional functions. This additional component allows the force transmission surface for the threaded bushing to be shifted to a more favorable position in the stop position, regardless of the extension's shape.

[0014] It is further proposed that a second torsion bar be provided, which has a higher plastic deformation limit than the first torsion bar, and which is connected to the first extension of the belt spool via a torque tube and a releasable second locking device, with the stop located on the torque tube, which is directly or indirectly supported by the first extension of the belt spool. The second torsion bar with the higher plastic deformation limit enables a two-stage force limitation curve, in which the force limitation level is defined by the high force limitation level of the second torsion bar when the second locking device is locked, and by the lower force limitation level of the first torsion bar when the second locking device is released.The torque tube serves to transmit torque when activating the second torsion bar. Releasing the second locking device releases the torque tube, thereby canceling the torque transmission to the second torsion bar and activating the first torsion bar. This torque tube then serves a second function: it forms the stop for the threaded bushing, thus enabling the force-limited extension of the webbing.

[0015] It is further proposed that the threaded bushing be formed by a ring that encompasses the torque tube, and that the ring have a radially inwardly projecting collar at one end, and that the stop be formed by an end face of the torque tube against which the threaded bushing comes into contact with the collar during the sliding movement. The threaded bushing thus encompasses the torque tube and, during the sliding movement, is moved towards the end face of the torque tube with the collar. This results in a very compact design while simultaneously ensuring a reliable stop function.

[0016] Alternatively, the stop can be formed by a component that rests against the frame of the seatbelt retractor and is positioned so that it projects into the path of travel of the threaded bushing. The advantage of this solution is that the stop thereby has a particularly stable and vehicle-resistant support point within the frame.

[0017] The invention is explained below with reference to preferred embodiments and the accompanying figures. Fig. 1 a belt retractor according to the invention before the activation of a force limiting device in sectional view, and Fig. 2 the belt retractor according to the invention after activation of the force limiting device in a sectional view, and Fig. 3 the seatbelt retractor of the Fig. 2 with further alternative embodiments of the stops.

[0018] In the Fig. Figure 1 shows a seatbelt retractor 1 with a belt spool 2 rotatably mounted in a frame 3, which is equipped with various additional components. These include a force limiting device 4 and an irreversible pyrotechnic tensioning device 6. The seatbelt retractor 1, together with the frame 3 and the belt spool 2 mounted therein, can be held in a larger housing along with the additional components, or it can be attached directly to the vehicle structure via the frame 3. The housing can be used to mount the seatbelt retractor 1 in the backrest of a vehicle seat or in an elongated installation space within the vehicle structure. Furthermore, an electric motor can be provided for reversible belt tensioning and various other comfort functions, such as a retraction aid, spring adjustment, or seatbelt warning.

[0019] The force limiting device 4 comprises a first torsion bar 8, a second torsion bar 9, a profile head 5, and a second switchable locking device 16, which is coupled to a switching device 17 that may be designed, for example, according to the model of the switching device disclosed in DE 199 27 427 A1. The profile head 5 is a carrier of a first locking device 7 in the form of a pivotable locking pawl, which, when activated by a belt extension acceleration-sensitive sensor device and / or a vehicle acceleration-sensitive sensor device, locks the profile head 5 by engaging a toothed connection on the frame 3 in the extension direction of a safety belt (not shown) wound on the belt spool 2.

[0020] The belt spool 2 has a first tubular extension 11, which is arranged on an end face of the belt spool 2 and extends towards the profile head 5. The first tubular extension 11 has a profiled receptacle that is open axially to the outside. The first torsion bar 8 is fixedly fixed at its first end 25 in the receptacle of the first extension 11 and has an external profile corresponding to the profile of the receptacle. Furthermore, a torque tube 10 is provided, which projects into the first extension 11 and encompasses the first torsion bar 8. The torque tube 10 is connected to the first extension 11 and thus to the belt spool 2 via the switchable second locking device 16.

[0021] The torque tube 10 simultaneously serves as a rotationally fixed connection between the second profiled end 26 of the first torsion bar 8 and the first profiled end 27 of the second torsion bar 9. For this purpose, the torque tube 10 has a central section with radially inwardly directed projections with which it engages in the outer profiles of the second end 26 of the first torsion bar 8 and the first end 27 of the second torsion bar 9, thereby connecting both ends to each other in a rotationally fixed manner.

[0022] The profile head 5 also has a central profiled receptacle, which is arranged in a second extension 12 extending in the axial direction. The second extension 12 of the profile head 5 is located on the end face of the profile head 5 and extends towards the belt spool 2, i.e., towards the first extension 11 of the belt spool 2. Furthermore, the torque tube 10 has an annular extension at its end, with which it bears against the second extension 12 of the profile head 5. Since the profile head 5 is itself mounted separately from the belt spool 2, it forms a frame-fixed abutment for the torque tube 10 in the locked position.

[0023] To activate the force limiting device 2, the profile head 5 is first locked to the vehicle via the first locking device 7 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.

[0024] 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 2 to rotate in the extension direction of the seat belt until further rotation is blocked by the locking mechanism of the profile head 5. Subsequent extension of the belt is only possible if this is enabled by activation of the force limiting device 4 and plastic deformation of the two torsion bars 8 and 9.

[0025] Before the second locking device 16 is engaged, the torque tube 10 is rotationally fixed to the belt spool 2, the first extension 11, the second end 26 of the first torsion bar 8, and the first end 27 of the second torsion bar 9, thus disengaging the first torsion bar 8 from the force flow. During this phase, the second torsion bar 9 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 9. The second torsion bar 9 has a higher force-limiting level than the first torsion bar 8, resulting in a high force-limiting level during this phase. In this case, the torque tube 10 rotates relative to the locked profile head 5 and is supported on the second extension 12 of the profile head 5.

[0026] By activating the second locking device 16 via the switching device 17, the connection between the torque tube 10 and the first extension 11 is released. The first torsion bar 8 is then in the force flow from the belt spool 2 to the frame 3. Since the first torsion bar 8 has a lower force limiting level than the second torsion bar 9, the second torsion bar 9 acts as a fixed bearing, and the second end 26 of the first torsion bar 8 is also blocked due to its connection with the first end 27 of the second torsion bar 9 via the torque tube 10. As a result, the first end 25 of the first torsion bar 8 rotates relative to the blocked second end 26, and the first torsion bar 8 is plastically deformed about its longitudinal axis. The lower force limiting level now applies.In this case, the torque tube 10 is blocked by the positive locking connection with the first end 27 of the second torsion bar 9, and the belt spool 2 rotates relative to the torque tube 10.

[0027] In an alternative embodiment, the belt retractor can also be provided with a force-limiting device 4 which comprises only a first torsion bar 8. In this case, the second end 26 of the first torsion bar 8 is fixed in a rotationally fixed manner in the receptacle of the second extension 12 of the profile head 5. The second switchable locking device 16, the torque tube 10, and the second torsion bar 9 can thus be omitted. In this case, the first torsion bar 8 would create a rotationally fixed connection between the belt reel 2 and the profile head 5 until the plastic deformation limit of the first torsion bar 8 is reached. The activation of the force-limiting device 4 in this case is achieved solely by the plastic deformation of the first torsion bar 8 to realize a single force-limiting level.

[0028] Furthermore, the force limiting device 4 has a threaded bushing 13, which has a cylindrical shape with a radially inwardly extending collar 29 at its right end. The threaded bushing 13 has an internal thread 15 in its left section, which engages with an external thread 14 of the first extension 11 of the belt spool 2. The collar 29 defines a radially internal non-circular opening in the threaded bushing 13, by which it is guided rotationally fixed and slidably on the second extension 12 of the profile head 5.

[0029] The threaded bushing 13 is thus supported in a rotationally fixed manner against the second extension 12 of the profile head 5 via the collar 29 during the rotational movement of the belt spool 2 in the extension direction. At the same time, due to the thread engagement of the internal thread 15 with the external thread 14, the threaded bushing 13 forms a threaded drive with the first extension 11, which converts the rotational movement of the belt spool 2 and the first extension 11 during the force-limited belt extension into a sliding movement of the threaded bushing 13 relative to the second extension 12 and the first extension 11.

[0030] The threaded bushing 13 is then inserted into the Fig. The direction of the arrow 2 is shifted until its edge 30 of the collar 29 comes into contact with an end face 18 of the torque tube 10. The end face 18 of the torque tube 10 thus forms a stop to limit the displacement of the threaded bushing 13 and, consequently, the rotation of the first extension 11 and the belt spool 2. This creates a force-limiting characteristic with a stop of the force-limited belt extension. The torque tube 10 is supported against the first extension 11 either by its rear end face coming into contact with a cone 19 of the cavity in the extension 11 or by a shoulder on the end face of the extension 11. In the stop position of the threaded bushing 13, the torque tube 10 thus provides indirect support for the threaded bushing 13 against the first extension 11 of the belt spool 2.

[0031] In the Fig.Figure 3 shows further alternative embodiments of a stop for limiting the force-limited extension movement. One possibility is formed, for example, by a radially inner annular shoulder 23 on the threaded bushing 13, with which the threaded bushing 13 comes to rest against the end face of the first extension 11 in the stop position. The annular section can preferably be arranged such that it connects directly to the internal thread 15 and axially limits it.

[0032] Furthermore, the stop can also be formed by an annular disk 24 or 21 that is axially supported on the switching device 17 or another housing wall or on the frame 3, and which is arranged so that it projects into the travel path of the threaded bushing 13. For this purpose, a stop ring 22 can additionally be provided on the threaded bushing 13, which is dimensioned such that it radially overlaps the annular disk 21 in an annular section 20.

[0033] In the stop position, the threaded bushing 13 forms a rotationally fixed connection between the two extensions 11 and 12, thus bridging the force limiting device 4 located between them and removing it from the force flow. This results in a force limiting characteristic with a stepped or constant force limiting level, depending on the design of the force limiting device 4, and a stop function, i.e., a defined stop of the force-limited belt extension.

[0034] The stop is preferably arranged directly or indirectly on the part that is also part of the threaded pairing, thus defining the triggering and the path of the displacement movement of the threaded bushing 13. In the present embodiments, the first extension 11 of the belt spool 2 is provided with the external thread 14, so that the stop is preferably provided directly on the first extension 11. A direct connection of the stop to the first extension 11 is achieved by the end face of the first extension 11, against which the threaded bushing 13 with the inner annular shoulder 23 comes into contact. An indirect connection of the stop to the first extension 11 is achieved by the torque tube 10 and the design of the end face 18 of the torque tube 10 as a stop, in that the torque tube 10 is axially supported on the first extension 11. 1 seatbelt retractor 2 belt reels 3 frames 4 Force limiting device 5 Profile head 6 Penal Institution 7 First blocking device 8 First torsion bar 9 Second torsion bar 10 Torque tube 11 First extension 12 Second Appendage 13 Threaded bushing 14 external threads 15 internal threads 16 Second locking device 17 Switching device 18 Front 19 cone 20 inner diameter 21 Ring 22 Ring 23 ring heel 24 ring disc 25 First End 26 Second Ending 27 First End 28 Second Ending 29 collars 30 Marginal page QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 199 27 427 A1 [0004, 0019] DE 10 2020 211 209 A1

[0006]

Claims

[1] Belt retractor (1) comprising -a belt spool (2) rotatably mounted in a frame, and -a force limiting device (4) with at least one plastically deformable first torsion bar (8), wherein -the first torsion bar (8) has a first end (25) which is non-rotatably connected to the belt spool (2) and a second end (26) which is directly or indirectly non-rotatably connected to a profile head (5) which can be locked to the vehicle via a first locking device (7), 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 / or the second extension (12), characterized by , that -a threaded bushing (13) is provided which engages in a thread with one of the extensions (11, 12) and is axially displaceable and rotationally fixed to the other extension (11, 12), and -a stop is provided which blocks the axial displacement movement of the threaded bushing (13) in a stop position and thus limits a further rotational movement of the belt spool (2) relative to the profile head (5). [2] Belt retractor (1) according to claim 1, characterized by , that -the stop is associated with the extension (11,12) which engages with the threaded bushing (13) in the threaded engagement. [3] Belt retractor (1) according to claim 2, characterized by , that -the stop is located directly on the extension (11,12). [4] Belt retractor (1) according to claim 2, characterized by , that -the stop is formed indirectly by a part that rests against the extension (11,12). [5] Belt retractor (1) according to claim 4, characterized by , that -a second torsion bar (9) is provided which has a higher plastic deformation limit than the first torsion bar (8), and -is connected to the first extension (11) of the belt spool (2) via a torque tube (10) and a detachable second locking device (16), and -the stop on which the torque tube (10) is arranged, which is directly or indirectly supported on the first extension (11) of the belt spool (2). [6] Belt retractor (1) according to claim 5, characterized by , 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 into contact with the collar (29) during the sliding movement. [7] Belt retractor according to claim 1, characterized by , that -the stop is formed by a part which is supported on the frame (3) of the belt winder (1) and which is arranged in such a way that it projects into the displacement path of the threaded bushing (13).

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