Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
1999-06-04
2001-03-27
Jillions, John M. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
Reexamination Certificate
active
06206315
ABSTRACT:
The invention relates to a unit comprising at least two torsion bars for limiting the force in a belt retractor.
BACKGROUND OF THE INVENTION
One such assembly using a first, hollow torsion bar and a second torsion bar arranged in the interior of the first torsion bar is known from German published patent application 196 53 510. This unit allows, for instance in a collision, that belt webbing can be withdrawn in overcoming a predetermined resisting force to diminish peak loads in the seat belt and thus the resulting risk of injury to the restrained vehicle occupant. The resistance to withdrawal of the belt webbing is determined by the moment of torsional resistance effective in each case. This resistance may be adapted to the individual requirements by alternatively activating one or the other torsion bar or by commonly activating both thereof.
The disadvantage with this known belt retractor is that varying the resulting characteristic of the resisting force over the length of the withdrawn belt webbing necessitates a complicated and bulky mechanism which switches the various torsion bars as desired with the necessary safety.
The object of the invention consists in providing a unit for limiting the force in a belt retractor in which the resulting characteristic of the belt webbing withdrawal force can be varied over the length of the withdrawn belt webbing as desired, without making any complicated external control mechanisms necessary for the switching action.
BRIEF DESCRIPTION OF THE INVENTION
For this purpose there is provided a unit comprising at least a first and a second torsion bar for limiting the force in a belt retractor. The first torsion bar is hollow, and the second torsion bar is arranged in the interior of the first torsion bar. The first torsion bar has an inner diameter which is at least in part selected such that the first torsion bar is supported at least in a twisted condition by the second torsion bar. This results in a further parameter with which the moment of torsional resistance furnished as a whole by the two torsion bars may be varied. A hollow torsion bar tends namely to constrict or completely collapse when exposed to high loads. The second torsion bar serving to support the first torsion bar influences the resisting moment provided by the first torsion bar at the point in time at which the support begins to become effective. Thus, very many different operating conditions may be established, for example a shearing off of the first torsion bar or a predetermined shortening of the first torsion bar which may be made use of to pull it out of a mount initially serving for transmission of force, so that it is no longer involved in transmitting the torque.
REFERENCES:
patent: 3857528 (1974-12-01), Fiala
patent: 5522564 (1996-06-01), Schmidt et al.
patent: 5820058 (1998-10-01), Hirzel et al.
patent: 5961060 (1998-10-01), Brambilla et al.
patent: 19653510 (1997-06-01), None
patent: 19733787 (1998-12-01), None
patent: 9632303 (1996-10-01), None
patent: 9749583 (1997-12-01), None
Jillions John M.
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
TRW Occupant Restraint Systems GmbH & Co. KG
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