GB2521769A

GB2521769A - Seatbelt assembly for a vehicle

Info

Publication number: GB2521769A
Application number: GB1422663.3A
Authority: GB
Inventors: Gopal Krishnan Chinnaswamy; Kalyan Cheruvu
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2014-12-18
Filing date: 2014-12-18
Publication date: 2015-07-01

Abstract

A seatbelt assembly 10 for a vehicle with a retractor unit 12 for retracting the seatbelt, the retractor unit 12 being coupled to a mounting plate 20 of the seatbelt assembly 10, at least one deformable element 34, 36 enabling the retractor unit 12 to move relative to the mounting plate 20 dependent on a load applied to the seatbelt, the at least one deformable element 34, 36 being at the mounting plate 20, the retracting unit 12 is coupled to the mounting plate 20 by means of a bolt 22, a shaft 26 of the bolt 22 is configured to move along a tapering slot 28, which is lined by the at least one deformable element 34, 36. The retractor unit 12 may be restrained by a locking means which is released by an actuator effected by a pyrotechnic element.

Description

Seatbelt Assembly for a Vehicle The invention relates to a seatbelt assembly for a vehicle. The seatbelt assembly comprises a retractor unit for retracting the seatbelt. The retractor unit is coupled to a mounting plate of the seatbelt assembly. At least one deformable element enables the retractor unit to move relative to the mounting plate dependent on a load applied to the seatbelt. Herein the at least one deformable element is provided at the mounting plate.

Such a seatbelt assembly is described in document US 5 211 694 A. Therein a seatbelt retractor comprises a housing with a tongue-like wall, which is fixed to a coupling member by means of a connecting pin. The connecting pin is arranged in a vertical slot provided in the coupling member. During a crash a traction force applied to the seatbelt fixed to the retractor leads to a movement of the pin along the vertical slot provided in the coupling member.

Another seatbelt system with a retractor which is movable with respect to a mounting plate is described in document US 5 566 978 A. Here a honeycomb material is disposed within a mounting bracket. A wall of the mounting bracket, which supports the retractor of the seat belt can move together with the retractor. This causes a sidewall of the mounting bracket to compress the honeycomb material.

Those seatbelt assemblies are comparatively complex.

It is therefore an object of the present invention to provide a seatbelt assembly of the initially mentioned kind, which is particularly simple and effective in controlling the seatbelt load.

This object is solved by a seatbelt assembly having the features of claim 1. Advantageous configurations with convenient further developments of the invention are specified in the dependent claims.

The retractor unit of the seatbelt assembly according to the invention is coupled to the mounting plate by means of a bolt. A shaft of the bolt is configured to move along a tapering slot, which is delimited by the at least one deformable element. Thus the movement of the shaft along the tapering slot and (together with the shaft) of the retractor unit relative to the mounting plate depends on the scat belt load. Further, a standard retractor unit can be utilized, as the deformable element is provided at the mounting plate.

As a change in the position of the retractor unit is enabled, there is a variety of design options for the restrain system. Further, the load exerted by the seatbelt on an occupant of the vehicle is controlled by energy absorption at the fixture of the retractor unit, as the shaft moves along the slot with the diminishing width in the direction of movement of the shaft of the bolt. Such a seatbelt assembly can be particularly easily implemented and can also easily meet the strength requirements and the structure requirements of a seatbelt assembly.

By allowing the shaft of the bolt to move along the tapering slot injuries of the occupant utilizing the seatbelt assembly are reduced during a crash of the vehicle. This is due to the fact that the seatbelt load is controlled by the utilization of energy absorption, which is self-adaptive depending on the load at the fixture. The absorption of energy takes place at the deformable element, as the shaft of the bolt deforms the deformable element during the movement of the retractor unit relative to the mounting plate. Further, the position of the retractor unit during a crash of the vehicle is dynamic.

As the shaft of the bolt can move along the tapering slot, a very simple and effective way of controlling the seatbelt load is provided by the seatbelt assembly.

The seat belt assembly therefore allows for a dynamic positioning of the retractor unit based on the load applied to the bolt which is utilized for fixing the retractor unit to the mounting plate, wherein this dynamic positioning reduces the load applied to the seat occupant. The movement of the bolt along the tapering slot thus constitutes a load limiting system, which restricts the movement of the retractor unit or retractor assembly based on the load at the location of the fixture of the retractor unit to the mounting plate.

The distance moved by the retractor assembly is defined by the load applied by the seat occupant when pulling the seatbelt. A further factor which influences the distance of movement is a stiffness or deformability of the deformable element, which can be a load-limiting block.

The tapering slot can be very easily be provided, if it is delimited by a first deformable element and a second deformable element arranged at opposite sides of the slot.

It has further proven advantageous, if a center axis of the slot forms an angle with a longitudinal axis of the vehicle. Thus, a very high degree of occupant safety can be achieved as the angle of the load-limiting slot can be chosen accordingly. By providing the angle a movement of the retractor unit in a forward direction of the vehicle coupled with a movement from a side of the vehicle towards a central plane of the vehicle, i.e. in an inward direction, can help reducing injuries of the seat occupant during a vehicle crash which leads to the application of the load to the seatbelt.

The at least one deformable element can in particular be wedge-shaped. Herein a side face of the at least one deformable element, which is in contact with the shaft of the bolt, preferably has a metal coating. Thus, the shaft can easily slide along the side face until the shaft is blocked in a blocking position within the tapering slot. The blocking position is in particular dependent on a weight of the seat occupant.

Further advantageously the seatbelt assembly can comprise blocking means configured to restrain the retractor unit in an initial position. Herein the seatbelt assembly further comprises an actuator configured to release the retractor unit by unlocking of the locking means.

In such a seatbelt assembly the retractor unit has a well-defined initial position, in which normal loads can be applied to the seatbelt without moving the retractor unit along the mounting plate. Such normal loads can for example occur during a fastening operation of the seatbelt, which is performed by the seat occupant. However, an impact or crash of the vehicle will lead to a release of the retractor unit by unlocking of the locking means.

Preferably, the seatbelt assembly comprises a control unit configured to activate a seatbelt tensioner prior to operating the actuator. The control unit therefore first activates the pre-tensioner, as an impending impact of the vehicle is detected based for example on a sensor input. With such a combination of a seatbelt pre-tensioning followed by the load-limiting movement of the retractor unit a particularly high occupant safety can be achieved.

For example a delay of about 2 ms to 10 ms can be provided between the activation of the seatbelt tensioner and the operation of the actuator, which leads to the unlocking of the locking means retaining the retractor unit in its initial position.

A particularly reliable unlocking of the locking means can be achieved if the actuator comprises a pinion element meshing with a rack element and with a stopper element.

Herein the stopper element preferably locks the retractor unit in the initial position.

Advantageously, a movement of the pinion can be effected by a pyrotechnical element.

The utilization of the pyrotechnical element provides for a very quick release of the retractor unit.

The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of figures and/or shown in the figures alone are usable not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention.

Thus, implementations are also to be considered as encompassed and disclosed by the invention, which are not explicitly shown in the figures or explained, but arise from and can be generated by separated feature combinations from the explained implementations.

Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments as well as based on the drawings.

Therein show: Fig. 1 in a schematic side view a seatbelt assembly comprising a retractor unit fixed to a mounting plate, wherein a bolt fixing the retractor unit to the mounting plate can move along a slot provided between two deformable elements fixed to the mounting plate in case a load is applied to the retractor unit due to a crash of a vehicle equipped with the seatbelt assembly; Fig. 2 the seatbelt assembly according to Fig. 1 in a top view; Fig. 3 a possible orientation of a center axis of the slot provided between two wedge-shaped deformable elements with respect to a longitudinal axis of the vehicle; Fig. 4 different end positions or blocking positions of a shaft of the bolt moving along the tapering slot dependent on a load applied to the seatbelt during the crash; Fig. 5 in a perspective view one of the deformable elements fixed to the mounting plate and delimiting the tapering slot; Fig. 6 a control system configured to activate a seatbelt pre-tensioner and to subsequently release the retractor unit by activation of a stopper mechanism; Fig. 7 in a section view along a line VIl-VIl in Fig. 1 the stopper mechanism in a locking position, in which the retractor unit is restrained from leaving its initial position; and Fig. 8 the stopper mechanism in a position allowing the retractor unit to move.

Fig. 1 shows a seatbelt assembly 10 for a vehicle comprising a retractor unit 12 or retractor assembly with a seatbelt spool 14 arranged in the retractor unit 12. The seatbelt 16 can be pulled out of the retractor unit 12 in a direction indicated by an arrow 18 in Fig. 1. In the event of a crash or such an impact of the vehicle equipped with the seatbelt assembly 10 a load is applied to the seatbelt 16 in the seatbelt direction of pull indicated by the arrow 18.

The retractor unit 12 is fixed to a mounting plate 20 of the seatbelt assembly 10 by means of a bolt 22 comprising a head 24 and a shaft 26. The bolt 22 or bolt assembly can in particular comprise a nut (not shown). The shaft 26 passes through the mounting plate 20 in the region of a tapering slot 28 provided in the mounting plate 20 (see Fig. 2).

As can be particularly well seen from Fig. 2, the seatbelt assembly 10 comprises a stopper element 30 with a stopper shaft 32 which restrains the bolt 22 and thus the retractor unit 12 in an initial position, which can in particular be ala first end 42 (see Fig. 4) of the slot 28.

The tapering slot 28 is provided between Iwo deformable elements 34, 36 or deformable blocks. These deformable elements 34, 36 are wedge-shaped (see Fig. 5) and are fixed to the mounting plate 20 in a rectangular cutout region shown in Fig. 2. As can be seen from Fig. 1, the deformable elements 34. 36 can have a height which corresponds to a thickness of the mounting plate 20.

Fig. 3 shows possible orientations of the tapering slot 28 with respect to a vehicle longitudinal axis X and a vehicle transverse axis Y. Accordingly, the center axis 38 of the slot 28 can form an angle 40 with the longitudinal axis X instead of being parallel to the longitudinal axis X. Such an orientation of the slot 28 leads to a movement of the shaft 26 of the bolt 22 along the tapering slot 28 in a forward direction of the vehicle and in an inward direction as the load is applied to the seatbelt 16 and thus to the retractor unit 12.

Possible movements of the shaft 26 along the slot 28 are illustrated in Fig. 4. As a load is applied to the seatbelt 16, this load is transmitted to the fixture of the retractor unit 12, in the example shown to the bolt 22. The shaft 26 of the bolt 22 can move along the slot 28.

However, the slot 28 is narrower in a direction from the first end 42 to a second end 44 of the slot 28 (see Fig. 4). This is due to the positioning of the wedge-shaped deformable elements 34, 36 within the rectangular cutout region provided in the mounting plate 20.

Thus, the shaft 26 will be blocked in a blocking position at a certain distance from the first end 42 of the slot 28.

This distance, however, is dependent on the load applied to the seatbelt 16. Fig. 4 shows a first travel distance 46 of the shaft 26 or such a retractor fixture along the tapering slot 28 due to a seatbelt load by a 5th percentile occupant. Thus the blocking position of the shaft 26' is at the distance 46 from the initial position of the shaft 26 within the slot 28. A further distance 48 of the shaft 26' from the first end 42, which has moved along the slot 28 corresponds to a seatbelt load by a 50th percentile occupant. And a third, still longer distance 50 of the shaft 26' moved along the slot 28 is due to a seatbelt load by a g5th percentile occupant.

Fig. 5 shows one of the wedge-shaped deformable elements 34 which are arranged in the rectangular cutout region within the mounting plate 20. Herein a first side wall 52 and a second side wall 54 of the respective deformable element 34, 36 are fixed to the mounting plate 20. The wedge-shaped elements 34, 36 have another side wall or side face 56, which preferably has a metal coating 58. This metal coating 58 can be provided by a thin steel plate for example.

This metal coating 58 is in contact with the shaft 26 of the bolt 22 as the shaft 26 moves along the slot 28, i.e. as the retractor unit 12 is pulled in the direction of pull indicated by the arrow 18 in Fig. 1. A space between the coated side face 56 and the other side walls 52, 54 of the wedge-shaped elements 34, 36 can be void or have a fill material such as a foam material. The deformable elements 34, 36 constitute load limiting blocks within the mounting plate 20.

As can be seen from Fig. 6 the seatbelt assembly 10 comprises a control unit 60, for example an electronic control unit. The control unit 60 receives a signal from a crash sensor 62. Due to this signal from the crash sensor 62 the control unit 60 activates a seatbelt tensioner 64 or pre-tensioner. This activation takes place a few milliseconds after the control unit 60 has received the signals from the crash sensor 62 indicating the impending crash of the vehicle.

The control unit 60 also activates a stopper mechanism 66 comprising the stopper element 30 (see Fig. 2). However, this activation of the stopper mechanism 66 takes place with a certain delay in time with respect to the activation of the tensioner 64. This time delay can be in the range of about 2 ms to about 10 ms. Due to this delay time the stopper mechanism 66 will only be activated after the pre-tensioner is initiated. The delay time can be optimized based on the vehicle crash characteristics and on sensor limitations. The stopper mechanism 66 and the seat belt tensioner 64 or pre-tensioner can in particular be activated utilizing a pyrotechnical element.

A possible way of activating the stopper mechanism 66 or such an actuator which can be operated by the control unit 60 is illustrated in Fig. 7 and Fig. 8.

Fig. 7 shows the stopper element 30 in a locking position, in which the shaft 26 of the bolt 22 is prevented from moving along the slot 28. This is due to the fact that the stopper shaft 32 of the stopper element 30 bears against the shaft 26 of the bolt 22 in the initial position of the shaft 26 within the slot 28 (see Fig. 2). The stopper mechanism 66 comprises a pinion 68 or pinion gear meshing with the stopper element 30 on the one hand, and with a rack 70 on the other hand. The stopper mechanism 66 further comprises an ignitor 72, a propellant 74, and a piston 76. An end face 78 of the piston 76 abuts against a hook element 80 of the rack 70.

By activating the stopper mechanism 66 the control unit 60 causes the ignitor 72 to ignite the propellant 74. This leads to a movement of the piston 76 and thus to a movement of the rack 70 by means of the pinion 68 (see Fig. 8). Consequently, the pinion 68 causes the stopper element 30 to retract the stopper shaft 32. Thus, the shaft 26 of the bolt 22 is free to move along the slot 28.

In Fig. 8 gas 82 formed upon the ignition of the propellant 74 is schematically shown. As the gas 82 occupies more volume than the propellant 74, the formation of the gas 82 causes the piston 76 to move. A moving direction of the piston 76 is indicated by an arrow 84 in Fig. 8. This movement of the piston 76 and therefore the rack 70 meshing with the pinion 68 causes the movement of the stopper element 30 in the opposite direction of the piston 76 moving direction. The moving direction of the stopper element 30 is indicated in Fig. 8 by a further arrow 86. As the stopper shaft 32 of the stopper element 30 (see Fig. 2) is no longer in contact with the shaft 26 of the bolt 22, the shaft 26 of the bolt 22 is free to move along the slot 28.

In the seatbelt assembly 10 the retractor unit 12 with the tensioner 64 and the load limiter provided by the deformable elements 34, 36 leads to an auto-positioning of the fixture of the retractor unit 12 in the tapering slot 28. Further, the continuous load limiting leads to an increase in safety for the seat occupant utilizing the seat belt assembly 10. A slot assembly comprises the stiffener blocks or load limiting blocks in the form of the deformable elements 34, 36, which can in particular have the metal layer coating 58. The retractor unit 12 or retractor assembly can in particular be fixed to a body-in-white panel of the vehicle.

Further, the pyrotechnical device for the activation of the auto-positioning is provided in the event of a crash. In this case the signals from the crash sensor 62 lead to an activation of the tensioner 64 or pre-tensioner. After the activation of the seatbelt tensioner 64 the pyrotechnical element in the form of the ignitor 72 and the propellant 74 is operated in a way that the stopper element 30 no longer restrains the retractor unit 12 in the design position or initial position shown in Fig. 4. This initial position corresponds to normal operating conditions of the seatbelt assembly 10, i.e. conditions without a crash or similar impact of vehicle.

In case of the crash, however, the pyrotechnical stopper mechanism 66 is activated alter the activation of the pre-tensioner. Then the movement of the shaft 26 along the slot 28 leads to limiting the load applied to the seatbelt 16 by the seat occupant. This helps reducing occupant injuries.

List of reference signs seatbelt assembly 12 retractor unit 14 seatbelt spool 16 seatbelt 18 arrow mounting plate 22 bolt 24 head 26 shaft 26 slot stopper element 32 stopper shaft 34 deformable element 36 deformable element 38 center axis angle 42 first end 44 second end 46 distance 48 distance distance 52 side wall 54 side wall 56 side face 58 metal coating control unit 62 crash sensor 64 seatbelt tensioner 66 stopper mechanism 68 pinion rack 72 ignitor 74 propellant 76 piston 78 end face hook element 82 gas 84 arrow 86 arrow X longitudinal axis Y transverse axis

Claims

Claims Seatbelt assembly for a vehicle, with a retractor unit (12) for retracting the seatbelt (16), which is coupled to a mounting plate (20) of the seatbelt assembly (10), and with at least one deformable element (34, 36) which enables the retractor unit (12) to move relative to the mounting plate (20) dependent on a load applied to the seatbelt (16), wherein the at least one deformable element (34, 36) is provided at the mounting plate (20), characterized in that the retractor unit (12) is coupled to the mounting plate (20) by means of a bolt (22), wherein a shaft (26) of the bolt (22) is configured to move along a tapering slot (28) which is delimited by the at least one deformable element (34, 36).
2. Seatbelt assembly according to claim 1, characterized in that the slot (28) is provided between a first deformable element (34) and a second deformable element (36).
3. Seatbelt assembly according to claim 1 or 2, characterized in that a center axis (38) of the slot (28) forms an angle (40) with a longitudinal axis (X) of the vehicle.
4. Seatbelt assembly according to any one of claims 1 to 3, characterized in that the at least one deformable element (34, 36) is fixed to the mounting plate (20).
5. Seatbelt assembly according to any one of claims 1 to 4, characterized in that the at least one deformable element (34, 36) is wedge shaped, wherein a side face (56) of the at least one deformable element (34, 36), which is in contact with the shaft (26) of the bolt (22) has a metal coating (58).
6. Seatbelt assembly according to any one of claims 1 to 5, characterized by locking means configured to restrain the retractor unit (12) in an initial position, wherein the seatbelt assembly (10) comprises an actuator configured to release the retractor unit (12) by unlocking of the locking means.
7. Seatbelt assembly according to claim 6, characterized in that the seatbelt assembly (10) comprises a control unit (60) configured to activate a seatbelt tensioner (64) prior to operating the actuator.
8. Seatbelt assembly according to claim 6 or 7, characterized in that the actuator comprises a pinion element (68) meshing with a rack element (70) and with a stopper element (30), wherein a movement of the pinion (68) can be effected by a pyrotechnical element (72, 74).
9. Seatbelt assembly according to claim 8, characterized in that the stopper element (30) comprises a shaft (32) which in the initial position of the retractor unit (12) bears against the shaft (26) of the bolt (22) by means of which the retractor unit (12) is coupled to the mounting plate (20).