Winding – tensioning – or guiding – Reeling device – With spring motor
Patent
1998-02-13
2000-08-22
Jillions, John M.
Winding, tensioning, or guiding
Reeling device
With spring motor
B60R 2228
Patent
active
061058947
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a self-locking belt roller with a vehicle-sensitive and/or seat belt-sensitive controllable blocking device, the belt roller being provided with a force limiting device for restricted belt withdrawal when a blocking member is engaged, the force limiting device comprising a torsion rod which is connected on the one hand to the belt winding shaft and on the other hand to the blocking member.
A belt roller having the above features is described in connection with a tightening device in DE 43 31 027 A1; however, the tightening device is not necessary for the function of the force limiting device in the known belt roller. In the known belt roller, the force limiting device is constructed as a torsion rod, so that particularly when used in connection with an airbag, the response of the force limiting device allows for an additional, but decelerated forward displacement of the belted occupant. This is achieved in that, in the event of loading, as the belt unwinds from the belt winding shaft the belt loading of the belt winding shaft blocked by the blocking member is reduced by the torsional rod which yields and allows for further rotation of the belt winding shaft.
The disadvantage associated with the known belt roller is that the acting force is increased by the force limiting device as a result of the cold deformation of the material and the decreasing winding diameter, i.e. as a result of the associated lever arm reduction; the associated force-path characteristic curve is progressive. In this context, further tests have shown that it is for example desirable for a higher restraining force to be exerted by the force limiting device at the start of an accident, namely so long as the belted person is not in contact with the airbag, and only to allow a reduced restraining force to be exerted via the belt roller once both safety devices are effective.
It is therefore the object of the invention to use suitable measures to better adapt the force-path curve in a belt roller of the generic type to the special features of the deceleration curve of the vehicle or of the vehicle occupants.
SUMMARY OF THE INVENTION
This object is attained by advantageous embodiments and developments of the invention and by the content of the claims which follow this description.
The idea which forms the basis of the invention is that, for connecting the torsion rod to the blocking member, a profile head, which is connected to the associated shaft end face and rotates together with the belt winding shaft, is provided as a support for the radially deflectable blocking member, and in the force transmission path between the torsion rod, profile head and shaft an additional energy-dissipating structure is provided for increasing the restraining force prior to the torsion rod becoming effective and for obtaining a stepped and/or degressive force-path characteristic curve. The invention offers the advantage that, prior to the force limiting device constructed as a torsion rod becoming effective, the vehicle occupant still participates as a result of the increased restraining forces in the relatively low initial deceleration of the motor vehicle and later upon contact with the airbag a lower restraining force is exerted via the force limiting device. In this respect, it may be expedient to adjust the force-path characteristic curve so that it decreases in step fashion or is generally degressive. Thus, the path of the chest acceleration or of the HIC index, for example, can be optimised by a degressive force-path characteristic curve of the force limiting device as a function of the deformation behaviour of a torsion rod.
In accordance with a first embodiment of the invention, the additional energy-dissipating structure is arranged between the belt winding shaft and the profile head, so that a relative movement between the belt winding shaft and the profile head is made possible by the uncoupling of the blocking member from the belt winding shaft. This relative movement can be exploited for
REFERENCES:
patent: 4322046 (1982-03-01), Tanaka et al.
patent: 5660347 (1997-08-01), Baker
patent: 5794877 (1998-08-01), Ono et al.
Clute Gunter
Singer Klaus-Peter
Witfeld Enno
Autoliv Development AB
Jillions John M.
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