Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
1999-02-03
2001-06-05
Walsh, Donald P. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
C280S805000, C280S806000
Reexamination Certificate
active
06241172
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a self-locking belt retractor with a locking device that is activated in a vehicle-sensitive and/or belt-sensitive manner, whereby the belt retractor has as a force-limiting device a torsion bar that allows, when the locking member is engaged a limited belt removal and is connected, on the one hand, to the belt reeling shaft and, on the other hand, by a profiled head to the locking member of the belt retractor. A device for adjusting the energy absorption of the torsion bar and adjusting the torsion bar to preselected incidents of loading is switched in the force-transmitting path between the torsion bar and the belt reeling shaft.
A self-locking belt retractor with the aforementioned features is known from DE 27 27470 A1. Inasmuch as the known belt retractor has a torsion bar as a force-limiting device, for an individual adjustment of the force level of the belt force limitation to the respective parameters set by the passenger, a continuos change of the clamping length of the torsion bar as a function of the weight of the passenger seated in the vehicle seat and/or of the allowed forward movement path is realized. For this purpose, a sliding sleeve connected to the belt reeling shaft and adjustable over the length of the torsion bar is provided which can be moved by an actuating device and, depending on its position, determines the torsion force and thus the free torsion length of the torsion available for force limitation.
In theory, the clamping length does not affect the force level for the belt force limitation, instead only the energy absorption capacity of the torsion bar is changed. Practical experiments in this context have shown that the effect of the clamping length of the torsion bar onto the force level is minimal and is not sufficient for practical applications. The invention has therefore the object to improve a belt retractor of the aforementioned features such that a change of the force level is possible over a wide adjustment range and furthermore also possible directly at the beginning or during an accident as a function of the loading conditions occurring in individual situations.
SUMMARY OF THE INVENTION
The invention is based on the principal idea that at least two force-limiting elements, arranged in parallel or in series relative to one another and controllable by a switching device that adjusts the energy absorption are provided, whereby one of the force-limiting elements is embodied by the torsion bar.
The inventive other force-limiting element, according to one embodiment of the invention, is embodied as a torsion sleeve surrounding the torsion bar whereby the torsion bar and/or torsion sleeve are connectable by a coupling element to the belt reeling shaft.
For this purpose, in a first embodiment it may be provided that the belt reeling shaft radially engages the end of the torsion bar and the torsion sleeve, respectively, and that at the belt reeling shaft a respective coupling pawl for the torsion bar as well as the torsion sleeve is arranged as a coupling element. Alternatively, it may be provided that the coupling element is embodied as a follower disc positioned at the end of the belt reeling shaft opposite the profiled head in positive locking, axially slidable connection with the belt reeling shaft. In its coupling position the follower disc couples the torsion bar and the torsion sleeve with one another by follower pins penetrating correlated abutting flanges of the torsion bar and the torsion sleeve.
In a second embodiment of the invention the adjustment of the force level is achieved in that as the other force-limiting element at least one resistance body is connected to the end of the belt reeling shaft opposite the profiled head. It revolves in a housing filled with a suitable material and is position-adjustable relative to the torsion bar.
In an alternative embodiment of the invention it may be provided that as the other force-limiting element the end of the belt reeling shaft opposite the profiled head is provided with a paddle wheel circulating in a housing filled with a suitable material whereby in the housing a friction plate is arranged so as to be axially moveable for adjustment of the material density.
Finally, in another embodiment of the invention, it is suggested that as a device for controlling the energy absorption capacity of the force-limiting device the torsion bar has at least two portions over its length separated by a connecting piece and having different cross-sections and that the portions of the torsion bar can be connected respectively to the belt reeling shaft by a coupling element between the belt reeling shaft and the respective connecting piece. In this context, the respective torsion bar can be embodied of two but also of three serially and formed-lockingly arranged or connected torsion bars.
With respect to the embodiment, respectively, arrangement of the coupling element, according to one embodiment of the invention it may be provided that either the end of the torsion bar is connected to the belt reeling shaft and the connecting piece separating the portions of the torsion bar are connectable by a controllable coupling pawl, supported at the belt reeling shaft, to the belt reeling shaft, or that alternatively at the end of the torsion bar a further connecting piece is arranged and as a coupling element a slide is provided that is fixedly coupled with respect to rotation to the belt reeling shaft, but axially moveably arranged thereat, and form-lockingly engages the connecting pieces. In this manner, it is possible to respectively couple the portions of different cross-sections of the torsion bar directly to the belt reeling shaft.
In more detail, according to one embodiment of the invention, it may be provided that at the connecting piece a sleeve surrounding the torsion bar may engage in a positive-locking manuever and the coupling pawl may be designed for fixation at the sleeve, whereby in an expedient manner the coupling pawl can be actuated by a pyrotechnical ignition pill arranged within the cross-section of the belt reeling shaft.
In another embodiment of the invention a multi-step adjustment of the torsion bar is provided instead of the two-step adjustment of the force limitation, and in this context it is suggested that, for adjusting a three-step energy absorption of the torsion bar, three portions separated by two connecting pieces are provided with different stepped cross-sections and each connecting piece has coordinated therewith a separate sleeve with coordinated coupling pawl.
Inasmuch as the connection between torsion bar and belt reeling shaft in individual cases is achieved by a sliding sleeve, it may be provided that as a coupling element a sliding sleeve is provided that is fixedly coupled with respect to rotation to the belt reeling shaft, but axially moveably arranged thereat, and engages the connecting pieces in a positive-locking manner.
In such an embodiment of the invention it may also be provided that the sliding sleeve is displaceable by a pyrotechnical ignition pill arranged within the cross-section of the belt reeling shaft. In this embodiment the gases released by the ignition pill will enter directly into the area of the sliding sleeve and will load it with respect to an axial movement.
As an alternative drive for the movement of the sliding sleeve it may be provided that for actuation of the sliding sleeve a pressure chamber is provided at the corresponding end face of the belt reeling shaft. A sliding disc is moveably arranged therein and the sliding disc is connected by a pawl engaging the disc and an attached pusher rod to the sliding sleeve and that the pressure chamber has an externally arranged ignition pill for releasing a pressure gas.
In this embodiment a three-step adjustment of the energy absorption is also provided since, for adjusting one of the three steps of the energy absorption level, the torsion bar has three portions separated by two connecting pieces with different stepped cross-section and the sliding
Clute Gunter
Fugel Frank
Autoliv Development AB
Pham Minh-Chau
Robert W. Becker & Associates
Walsh Donald P.
LandOfFree
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