Seat belt retractor

Abstract

The invention relates to a safety belt retractor comprising a safety belt reel (1) rotatably mounted in a frame and comprising a force limiting device (2) with at least one plastically deformable first torsion bar (9), wherein the first torsion bar (9) has a first end (11) which is connected in a rotationally fixed manner to the safety belt reel (1) and a second end (12) which is connected in a rotationally fixed manner to a profiled head (7) which can be locked in a fixed manner with respect to the vehicle by means of a first locking device. The safety belt reel (1), the first torsion bar (9) and the profiled head (7) are arranged coaxially with respect to one another and in series with respect to one another.

Description

[0001] This invention relates to a seatbelt retractor.

[0002] The seatbelt retractor has a load-bearing frame and a seatbelt reel as basic components. The seatbelt reel is rotatably mounted in the frame, and the seatbelt can be wound around the seatbelt reel. The frame is used not only to mount the seatbelt reel but also to secure the seatbelt retractor to the seat structure or vehicle structure, and for this purpose, it is made of steel plates of corresponding thickness bent into a U-shape.

[0003] Furthermore, modern seatbelt retractors are equipped with force-limiting devices to reduce occupant load. These force-limiting devices enable force-limited seatbelt deployment in the event of an accident, until, for example, the occupant is caught by an airbag. For this purpose, a plastically deformable torsion bar has proven effective. It is connected to the seatbelt reel at one end in a rotation-resistant manner and fixed at the other end to a component (a shaped head) that, in the event of an accident, can be locked relative to the vehicle by a first locking device. In such torsion bars, the force-limiting level of seatbelt deployment is predetermined by its plastic deformation limit.

[0004] Publication DE 199 27 427A1 discloses a seatbelt retractor having two torsion bars with two torsion portions having different plastic deformation limits. The two torsion bars are connected to a profiled head at their free ends, forming the end of the torsion portion with a higher force limiting level, in a way that resists relative rotation. The other free end is connected to the seatbelt reel in a way that resists relative rotation. Furthermore, a switchable second locking device is provided with a torque tube, which connects to a profiled portion of the torsion bar at the central portion of the profile, separating the two torsion portions from each other. The switchable second locking device also includes two releasable locking claws that lock the torque tube relative to the frame of the seatbelt retractor. Thus, the torsion portion with the lower plastic deformation limit (i.e., a lower force limiting level at the start of force-limited seatbelt pull-out) is bridged, and force-limited seatbelt pull-out is made possible by the plastic deformation of the torsion portion with the higher plastic deformation limit at a higher force limiting level. When the second locking device is switched, the locking of the torque tube is released, and the further force-limited seatbelt pull-out becomes possible through the plastic deformation of the torsion portion with a lower plastic deformation limit at a lower force-limiting level. The two-stage torsion bar is arranged together with the torque tube in the cavity of the seatbelt reel, thus requiring a seatbelt reel with a correspondingly sized cavity and a correspondingly sized outer diameter.

[0005] Furthermore, it is known to provide integrated seat belt devices for vehicle seats, wherein at least the seat belt retractor of the seat belt device is secured in the backrest of the vehicle seat. In this case, since there is no B-pillar to support it, and due to reasons related to the passageway to the rear seats or the distance from the rear vehicle structure, the seat belt retractor is preferably integrated into the backrest of the vehicle seat, and therefore the backrest must also be designed to absorb the tension acting under restraint. These seat belt retractors themselves have all the basic components of a standard seat belt retractor, and are only equipped with various additional sub-components specifically designed for installation in the backrest, such as self-aligning inertial sensors. Installation into the backrest is problematic because the available installation space is very small, and the backrest cannot be expanded according to installation needs, nor can its basic structure be changed as needed. In this case, the structure of the backrest is specifically designed to absorb restraint forces in the event of an accident using a frame made of struts, which are designed to form a structure with the greatest possible rigidity under the lowest possible self-weight. Due to this requirement, there inevitably exists a structure that can only be modified to a limited extent, which has as many long pillars as possible that divide the interior of the backrest into multiple slender free spaces.

[0006] In the case of seatbelt retractors, especially when they are designed to be installed in the backrest, this leads to the problem that they must be designed to be as compact as possible, and in particular, they must be designed to be installed in very narrow and elongated installation spaces.

[0007] To achieve this objective, a seatbelt retractor is proposed. Further preferred embodiments can be found in the accompanying drawings and related description.

[0008] According to the basic idea of ​​the present invention, the seat belt reel, the first torsion bar and the irregular head are arranged coaxially and connected in series with each other.

[0009] The proposed solution enables the realization of a slender and narrow basic structure for the seatbelt retractor. Compared to solutions known in the prior art, the first torsion bar is removed from the seatbelt reel and arranged coaxially with it, allowing the seatbelt reel to be designed with a smaller outer diameter by eliminating the cavity previously required to house the torsion bar within the reel. Furthermore, the irregular head, which can be locked relative to the vehicle via a first locking device, is also arranged coaxially with and in series with the seatbelt reel, allowing it to be released from the reel as well. Therefore, the seatbelt reel can also be made smaller for this reason, as the irregular head is no longer directly mounted on it. Moreover, the coaxial series arrangement of the three basic components achieves a very narrow and slender basic structure for the seatbelt retractor, making it easier to install in the existing narrow and slender mounting spaces of the backrest or vehicle structure. However, if the existing mounting space is insufficient, they can be slightly modified and adjusted.

[0010] The first torsion bar is preferably arranged in series between the seatbelt reel and the swivel head. The first torsion bar effectively forms the connection between the swivel head and the seatbelt reel. When the swivel head is locked, the second end of the first torsion bar is locked, and the first end of the first torsion bar can rotate relative to the locked swivel head together with the seatbelt reel under plastic deformation of the portion of the first torsion bar arranged between the first and second ends. This produces a simple and clear basic structure with the straightest possible force flow, allowing the seatbelt retractor to be designed very compactly for absorbing restraint forces.

[0011] Furthermore, it is proposed that the irregular head and the seatbelt reel are mounted axially spaced apart from each other in separate radial bearings. In the previous arrangement of the irregular head on the seatbelt reel, the irregular head simultaneously formed the radial bearing of the seatbelt reel, wherein the arrangement of the torsion bar and the radial bearing of the seatbelt reel in the irregular head resulted in a relatively large outer diameter of the seatbelt reel. With the proposed separate radial bearings, the installation of the seatbelt reel can be achieved more easily and thus in a manner optimized for installation space. In addition, the installation is more stable due to the arrangement of two bearings and the axial spacing of the radial bearings.

[0012] Furthermore, the first torsion bar is held at its first end in a receiving portion of the seatbelt reel that is open to the axial outward in a manner that resists relative rotation. Thus, the first torsion bar is connected to the first end on the outer side of the seatbelt reel in a manner that resists relative rotation, and extends coaxially from the receiving portion to the outer side of the seatbelt reel in the axial direction.

[0013] Furthermore, it is proposed that at least one second torsion bar be arranged between the first torsion bar and the irregular head in a manner coaxial with and connected in series with respect to the seat belt reel. By providing the second torsion bar, a higher or lower force limiting level of the force-limiting seat belt pull-out can be achieved depending on the actuation type.

[0014] Preferably, the second torsion bar and the first torsion bar can have different plastic deformation limits, so that a stepwise change in force limiting characteristics can be achieved by successively actuating the two torsion bars.

[0015] Preferably, a torque tube can be provided here, which is fixed relative to the seatbelt reel in a rotation-resistant manner by a switchable second locking device, wherein the torque tube connects the two facing ends of the first and second torsion bars to each other in a rotation-resistant manner. The first torsion bar can be intentionally bridged via the torque tube to actuate the second torsion bar during a first stage of force limitation. The first torsion bar is then actuated by switching the second locking device.

[0016] Furthermore, it is proposed that an axially protruding protrusion be provided on the seat belt reel, and the torque tube be fixed relative to this protrusion by a switchable second locking device. The axially protruding protrusion creates a force transmission surface on the seat belt reel, on which the torque tube is supported. Due to the arrangement of the protrusion, a force transmission surface is specifically created that does not increase the outer diameter of the seat belt reel, and allows for a particularly simple coaxial series arrangement of the torsion bar relative to the seat belt reel.

[0017] The axial protrusion can preferably be annular, and the torque tube can project radially inward into the annular protrusion, or surround the annular protrusion radially outward. Thus, the torque tube also has radial support and is radially mounted on the protrusion during rotational movements, particularly after the switching and release of the second locking device.

[0018] Furthermore, it is proposed that an axially protruding annular protrusion be provided on the irregular head, and the torque tube protrudes radially inward into or surrounds the annular protrusion radially outward. The advantage of the proposed solution is that the torque tube is supported on the irregular head by the annular protrusion and is mounted on the irregular head during relative rotational movement. This is advantageous, particularly since the solution according to the invention requires an increase in the overall axial length of the seatbelt retractor.

[0019] Furthermore, it is proposed that the seatbelt reel be designed as a solid shaft. By forming it as a solid shaft, a particularly compact design with very high dimensional stability can be achieved. For example, a form-locking design corresponding to the connection of the seatbelt can be provided in the seatbelt reel; in any case, the cavity previously required for arranging the torsion bar can be omitted. In addition, by designing the seatbelt reel as a solid shaft, an axial receiving portion for fixing the first end of the first torsion bar in a manner resistant to relative rotation can be implemented particularly easily.

[0020] The invention will now be explained using preferred embodiments with reference to the accompanying drawings. The following is shown:

[0021] Figure 1 A cross-sectional view shows a seatbelt retractor with different additional sub-components, and

[0022] Figure 2 A seatbelt retractor with a force limiting device is shown.

[0023] Figure 1 A seatbelt retractor with a seatbelt reel 1 rotatably mounted in a frame 8 is shown. The retractor is equipped with various additional sub-assemblies. Thus, a force limiting device 2, a motor 5, a transmission 4, and an irreversible pyrotechnic tightening device 19 are provided. The seatbelt retractor, along with the frame 8 and the seatbelt reel 1 mounted therein, as well as the additional sub-assemblies, are mounted in an upper housing 20. The housing 20 also serves to secure the seatbelt retractor to the back of a vehicle seat or in an elongated mounting space within the vehicle structure. The motor 5 is configured for reversible seatbelt tightening and various other comfort functions, such as a winding aid, a spring adjustment device, or a seatbelt operating device. The rotational motion driven by the motor 5 is converted via the transmission 4 and transmitted through a transmission rod 6 to the force limiting device 2, which in turn drives the seatbelt reel 1.

[0024] exist Figure 2 In the enlarged view, the seatbelt retractor, along with the seatbelt reel 1 and the force limiting device 2, can be seen. The frame 8 is supported on the housing 20, which forms a support for fixing the frame 8 to the vehicle in a position where it is mounted on a vehicle or seat. The force limiting device 2 is oriented coaxially with the axis of rotation of the seatbelt reel 1 on the end face of the seatbelt reel 1 and is connected to the seatbelt reel 1.

[0025] The force limiting device 2 includes a first torsion bar 9, a second torsion bar 10, a shaped head 7, and a second switchable locking device 3. The shaped head 7 is a carrier for a locking pawl (not shown), which forms the first locking device and locks the shaped head 7 during actuation of a sensor device sensitive to seatbelt pull-out acceleration and / or a sensor device sensitive to vehicle acceleration in the pull-out direction of the seatbelt (also not shown) wound onto the seatbelt reel 1. The seatbelt reel 1 is rotatably mounted in a frame 8, which is in turn fixed in a housing 20 in a manner resistant to relative rotation and can be fastened to a vehicle or backrest. The shaped heads 7 are radially mounted at axial intervals in a web 22 fastened to the housing 20. Therefore, unlike the previously used basic principle, the seatbelt reel 1 and the shaped heads 7 are mounted independently of each other and axially spaced apart. Thus, the seatbelt reel 1 in the frame 8 and the shaped heads 7 in the web 22 have separate and axially spaced radial bearings. Therefore, the sub-assembly consisting of the seat belt reel 1 and the force limiting device 2 can be installed in a more stable configuration, which is advantageous, especially during the actuation of the force limiting device 2.

[0026] The seatbelt reel 1 has a shaped receiving portion 15 that opens axially outward. A first torsion bar 9 is fixed in the receiving portion 15 with its first end 11 resisting relative rotation and has an outer contour corresponding to the contour of the receiving portion 15. The receiving portion 15 is surrounded by an annular protrusion 17 that extends axially away from the end face of the seatbelt reel 1. Furthermore, a torque tube 16 is provided, which engages in the protrusion 17 and surrounds the first torsion bar 9. The torque tube 16 is connected to the protrusion 17 with two locking claws resisting relative rotation via a switchable second locking device 3, wherein the locking claws are released according to the switching principle described in DE199 27 427A1.

[0027] The torque tube 16 is also used for anti-rotational connection between the second irregular end 12 of the first torsion bar 9 and the first irregular end 13 of the second torsion bar 10. For this purpose, the torque tube 16 has a central portion with a radially inwardly pointing protrusion, which engages with the outer contours of the second end 12 of the first torsion bar 9 and the first end 13 of the second torsion bar 10, thereby fixing the two ends against relative rotation.

[0028] The irregular head 7 also has a central irregular receiving portion 18, which is surrounded by an annular protrusion 21 extending in the axial direction. The second end 14 of the second torsion bar 10 is provided with an outer contour corresponding to the contour of the receiving portion 18, and is fixed in the receiving portion 18 relative to the irregular head 7 in a way that resists relative rotation. In addition, the torque tube 16 surrounds the annular protrusion 21 radially outward and is supported on the irregular head 7. Since the irregular head 7 is installed separately from the seat belt reel 1, the irregular head forms a support for the torque tube 16 fixed on the frame.

[0029] In order to activate the force limiting device 2, in the first step, when the seat belt pull-out acceleration or vehicle deceleration exceeds a predetermined value, the irregular head 7 is locked relative to the vehicle by the first locking device, wherein the excess of the predetermined limit value is detected by the aforementioned sensor device.

[0030] If the occupant moves forward due to inertia in the event of an accident, the seatbelt is pulled out, and the restraint force thus increases the tension in the seatbelt. Therefore, the seatbelt reel 1 rotates in the direction of seatbelt pull-out until further rotational movement is locked by the locking mechanism of the shaped head 7. Subsequently, the seatbelt can only be pulled out further if the plastic deformation of the two torsion bars 9 and 10 makes such seatbelt pull-out possible.

[0031] Before switching the second locking device 3, the torque tube 16 is connected to the seat belt reel 1, the protrusion 17, the second end 12 of the first torsion bar 9, and the first end 13 of the second torsion bar 10 in a rotationally resistant manner, such that the first torsion bar 9 is disengaged from the force flow. Therefore, in this stage, when 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 plastically deforms about its longitudinal axis. The second torsion bar 10 has a higher force limiting level than the first torsion bar 9, such that the higher force limiting level is effective in this force-limiting stage. In this case, the torque tube 16 rotates relative to the locked profile head 7 and is mounted on the annular protrusion 21 of the profile head 7.

[0032] By switching the second blocking device 3, the connection between the torque tube 16 and the protrusion 17 is canceled. Therefore, the first torsion bar 9 is positioned in 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 locked by the torque tube 16 due to its connection with the first end 13 of the second torsion bar 10. Therefore, the first end 11 of the first torsion bar 9 rotates relative to the locked second end 12, and the first torsion bar 9 plastically deforms about its longitudinal axis. The lower force limiting level now comes into play. In this case, the torque tube 16 is locked by a form-locking connection with the first end 13 of the second torsion bar 10, and the seatbelt reel 1 rotates relative to the torque tube 16, with the protrusion 17 of the seatbelt reel 1 additionally forming a bearing for the torque tube 16.

[0033] The invention has been described with reference to a force limiting device 2 having two torsion bars 9 and 10, which enable a stepped force limiting curve. The two torsion bars 9 and 10 are arranged coaxially and in series with each other, so that the outer diameter does not increase due to their arrangement. The seat belt retractor is therefore only slightly longer.

[0034] In an alternative embodiment, the seatbelt retractor may also be provided with a force limiting device 2 consisting only of a first torsion bar 9. In this case, the second end 12 of the first torsion bar 9 is fixed in the receiving portion 18 of the shaped head 7 against relative rotation. The second switchable locking device 3, the torque tube 16, and the second torsion bar 10 can therefore be omitted. In this case, the first torsion bar 9 will provide a resistance to relative rotation between the seatbelt reel 1 and the shaped head 7 until the plastic deformation limit of the first torsion bar 9 is reached. In this exemplary embodiment, the seatbelt retractor will also have a slender and narrow basic structure, and the outer diameter of the seatbelt reel 1 can be significantly smaller by the outward displacement of the first torsion bar 9. Except for the receiving portion for the end of the seatbelt, the seatbelt reel 1 can be designed as a solid shaft, and thus have maximum rigidity with the smallest possible external dimensions.

Claims

1. A belt retractor comprising - a belt reel (1) which is rotatably mounted in a frame, and - a force-limiting device (2) having at least one first torsion bar (9) which is plastically deformable, wherein - the first torsion bar (9) has a first end (11) which is connected to the belt reel (1) in a rotationally fixed manner and a second end (12) which is connected to a profiled head (7) in a rotationally fixed manner, the profiled head being able to be locked in a fixed manner with respect to the vehicle by means of a first locking device, the first torsion bar (9) being held in a rotationally fixed manner in a receiving portion (15) of the belt reel (1) which opens towards the axial outside at the first end (11), at least one second torsion bar (10) being arranged between the first torsion bar (9) and the profiled head (7) in a coaxial and series-like manner with respect to the belt reel (1), and the second torsion bar (10) and the first torsion bar (9) have different plastic deformation limits, characterized in that - the belt reel (1), the first torsion bar (9) and the profiled head (7) are arranged coaxially and in series with respect to one another, a torque tube (16) is provided which is fixed in a rotationally fixed manner with respect to the belt reel (1) by means of a switchable second locking device (3), wherein the torque tube (16) connects the two mutually facing ends of the first torsion bar (9) and the second torsion bar (10) to one another in a rotationally fixed manner, an axially projecting protrusion (17) is provided on the belt reel (1), the torque tube (16) is fixed with respect to the protrusion by means of the switchable second locking device (3), the protrusion (17) is annular, and the torque tube (16) projects radially inwards into an annular protrusion (21) or surrounds the annular protrusion (21) radially on the outside.

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

3. The belt retractor according to claim 2, characterized in that - the profiled head (7) and the belt reel (1) are mounted axially spaced apart from one another in separate radial bearings.

4. The belt retractor according to claim 1, characterized in that - an axially projecting annular protrusion (21) is provided on the profiled head (7), and - the torque tube (16) projects radially inwards into the annular protrusion (21) or surrounds the annular protrusion (21) radially on the outside.

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

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