Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Woven fabric – Woven fabric is characterized by a particular or...
Patent
1996-12-06
1999-06-08
Raimund, Christopher
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Woven fabric
Woven fabric is characterized by a particular or...
139383R, 139420R, D03D 2300
Patent
active
059104570
DESCRIPTION:
BRIEF SUMMARY
The invention relates to woven belt webbing for a vehicle occupant restraining system.
In particularly serious accidents the restraining forces of the belt webbing may be so great as to cause injuries to the vehicle occupant. For this reason vehicle occupant restraining systems are being fitted to an increasing extent with force limiting devices so designed that when a tension force as determined by the designer in the belt webbing is exceeded there is an increase in the length of the force limiting device with the conversion of energy with the result that load peaks in the restraining system may be reduced.
Such force limiting devices may for example be constituted by stretch means, which may be provided at one terminal fitting of the belt or on the belt retractor. The plastic deformation occurring when a predetermined tension load is exceeded, which leads to an increase in the length of the stretch means, may limit the belt force to a degree set by the designer. It is a disadvantage in such force limiting devices that they entail additional structural features and there is also the added danger of incorrect fitting thereof.
Limitation of force may also be achieved by using frangible elements, which are formed on the belt webbing as a sort of loop therein and which when a predetermined tension load is exceeded successively release an additional length of belt with the result that it is also possible to ensure a limitation of the tension strain to a predetermined degree. However, there is then a force limitation characteristic which may not be satisfactorily reproduced.
One object of the invention is to provide for force limitation using simple means on the belt webbing itself, whose force limiting characteristic may be readily set by the designer and is satisfactorily reproducible.
In order to achieve such aim in the context of a woven belt webbing same is characterized in that the warp threads possess lengths differing with each length unit of the belt webbing, that is to say in the form of short warp threads to bear the tensile load acting in the belt webbing up to a first stretch value of the belt webbing without loading the longer warp threads, and in the form of longer warp threads, which as from such stretch value of the belt webbing take part in withstanding the tensile load acting in the belt webbing in a manner dependent on the ratio of the length thereof to the length of the short warp threads. Such belt webbing means that there is no additional structural involvement for a force limiting device, since on exceeding a predetermined tensile load it is possible to ensure a controlled increase in length of the belt webbing by stretching of the shorter warp threads with the result that the tensile load acting in the belt webbing can be reduced to a degree determined by the designer. A further advantage of the belt webbing in accordance with the invention is that by judicious selection of the length ratios of the warp threads and the dimension thereof the characteristic of tensile load over stretch of the belt webbing may be freely selected over a wide range.
In the case of a preferred embodiment of the invention there is the provision that the longer warp threads are constituted by long warp threads of uniform length which as from the first stretch value, corresponding to the difference in length between the short and the long warp threads, of the belt webbing play a role in withstanding the tensile load acting in the same. Owing to the employment of warp threads with only two different lengths there is the advantageous compromise between cost-effective manufacturing on the one hand and sufficient possibility of variation of the characteristic: tensile load over stretch of the belt webbing on the other hand.
Further advantageous developments of the invention are defined in the dependent claims.
The preferred embodiment of the invention will now be described with reference to the accompanying drawings.
FIG. 1 shows a diagrammatic view of part of the belt webbing in accordance with the invention.
FIG.
REFERENCES:
patent: 3464459 (1969-09-01), Ballard
patent: 3530904 (1970-09-01), Ballard
patent: 3537488 (1970-11-01), LeBoeuf
patent: 3872895 (1975-03-01), Takada
patent: 4228829 (1980-10-01), Kikuchi
patent: 4662487 (1987-05-01), Koch
patent: 5376440 (1994-12-01), Koseki
Raimund Christopher
TRW Occupant Restraint Systems GmbH
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