Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-03-15
2001-04-10
Swann, J. J. (Department: 3611)
Land vehicles
Wheeled
Attachment
C297S480000
Reexamination Certificate
active
06213511
ABSTRACT:
DESCRIPTION
The present invention relates to a pretensioner and particular to a pyrotechnic pretensioner in which a seat belt is tightened when an impending crash condition is detected so as to ensure that there is no slack in the belt system. In a pyrotechnic pretensioner this slack is eliminated by pulling back a buckle anchorage of the belt system or rapidly rewinding a seat belt retractor by means of the force generated by an explosive charge.
However, known pretensioning arrangements do not distinguish between a situation where there is slack present in the belt system and one in which there is no slack present. With no slack in the system, a much larger pretensioning force is required and thus a much larger pyrotechnic charge. A problem arises in using a large pyrotechnic charge since when there is slack in the system this results in a high pretensioning acceleration which in itself can have an adverse effect on the vehicle occupant and may cause injury.
It is an object of the present invention to provide a pretensioner arrangement which overcomes the disadvantages of prior known systems and in particular can accommodate both slack and no slack conditions in the belt system.
According to the present invention there is provided a pretensioner for a vehicle safety restraint, for rapidly reducing slack in a safety restraint belt in the event of a crash situation, the pretensioner comprising a cable connected at one end to a piston and at its other end to a belt rewinding mechanism, the piston being slidably moveable in a cylinder under action of pressure from a gas generator sensitive to a crash indicator, wherein means are provided for controlling the rate of acceleration of the cable in the pretensioning direction, in dependence upon the condition of tension in the safety restraint belt which is to be pretensioned.
Preferably the pressure is controlled by varying the volume available to the gas. Alternatively, the size of a vent between parts of the volume may be controlled to control the pressure.
REFERENCES:
patent: 3999780 (1976-12-01), Matsuoka et al.
patent: 5056739 (1991-10-01), LeVay
patent: 5163708 (1992-11-01), Kotama
patent: 5282672 (1994-02-01), Borlinghaus
patent: 5294150 (1994-03-01), Steffens, Jr.
patent: 5772246 (1998-06-01), Gordon
Burke David
Downie Andrew John
Hill Mike
Smith David
Dunn David R.
Seitzman Markell
Swann J. J.
LandOfFree
Seat belt pretensioner does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Seat belt pretensioner, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seat belt pretensioner will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2446847