The present invention relates generally to seat restraint systems for vehicles and, more particularly, to a selectable load limiting seat restraint retractor for a seat restraint system in a vehicle.
It is known to provide a seat restraint system such as a seat belt in a vehicle to restrain an occupant in a seat of the vehicle. In some vehicles, the seat restraint system may be a lap restraint or belt, a shoulder restraint or belt, or both. Typically, the lap belt and shoulder belt are connected together at one end. The seat restraint system includes a latch plate at the connected end. The seat restraint system also includes a buckle connected at one end by webbing or the like to vehicle structure. The buckle receives the latch plate to be buckled together. When the buckle and latch plate are buckled together, the seat restraint system restrains movement of the occupant to help protect the occupant during a collision.
It is also known to provide a load limiting retractor for the seat restraint system. During a front impact of the vehicle, the load limiting retractor locks and rapid deceleration causes forward movement of the occupant and the occupant to load the seat restraint webbing. These load limiting retractors are used to payout or unspool seat restraint webbing under a constant load and allow the occupant to decelerate with the vehicle, thus limiting high seat belt restraint loads, thereby improving occupant performance. However, these load limiting retractors offer only one level of load limiting and are usually designed for mid sized occupants.
Therefore, it is desirable to limit the amount of restraint load on an occupant during an impact for a seat restraint system in a vehicle. It is also desirable to select the amount of load limiting based on a size and mass of the occupant during an impact for a seat restraint system in a vehicle. It is further desirable to provide multiple levels of load limiting such as both a high level and a low level for various size occupants during an impact in a seat restraint system of a vehicle. Thus, there is a need in the art to provide a selectable load limiting seat restraint retractor that meets these desires.
It is, therefore, one object of the present invention to provide a new selectable load limiting seat restraint retractor for a seat restraint system in a vehicle.
It is another object of the present invention to provide a selectable load limiting seat restraint retractor for a seat restraint system in a vehicle that has multi-level load limiting.
It is yet another object of the present invention to provide a selectable load limiting seat restraint retractor for a seat restraint system in a vehicle having both a high level and a low level of load limiting.
To achieve the foregoing objects, the present invention is a selectable load limiting seat restraint retractor for a seat restraint system in a vehicle including a first housing for operative connection to vehicle structure. The selectable load limiting seat restraint retractor also includes a rotatable take-up spool connected to webbing of a seat restraint system for winding and unwinding the webbing. The selectable load limiting seat restraint retractor further includes a rotatable first torsion bar operatively connected to the first housing to provide a first level of load limiting on the webbing during an impact. The take-up spool is operatively connected to the first torsion bar. The selectable load limiting seat restraint retractor includes a rotatable second torsion bar operatively connected to the first housing and orientated parallel to the first torsion bar to provide a second level of load limiting on the webbing during an impact. The second level of load limiting is less than the first level of load limiting. The selectable load limiting seat restraint retractor further includes a selectable load limiting mechanism operatively cooperating with the first torsion bar and the second torsion bar to select between the first level of load limiting and the second level of load limiting to provide digressive load limiting on the webbing during an impact.
One advantage of the present invention is that a selectable load limiting seat restraint retractor is provided for a seat restraint system in a vehicle having a digressive load limit. Another advantage of the present invention is that the selectable load limiting seat restraint retractor achieves multi-level load limiting and provides the desired effect of digressive load limiting. Yet another advantage of the present invention is that the selectable load limiting seat restraint retractor offers a high peak load level early in an impact prior to airbag contact and digresses to a lower load level as an occupant is restrained by the airbag, thereby spreading the impact loading more evenly throughout the impact. Still another advantage of the present invention is that the selectable load limiting seat restraint retractor allows larger sized occupants to benefit by receiving a high load limit level throughout the impact and from the additional load carrying capability of the seat restraint system. A further advantage of the present invention is that the selectable load limiting seat restraint retractor allows smaller sized occupants to benefit from a lower load limit because these occupants are in most cases fully restrained by the airbag and little additional restraint from the webbing is necessary. Yet a further advantage of the present invention is that the selectable load limiting seat restraint retractor maintains critical packaging dimensions. Still a further advantage of the present invention is that the selectable load limiting seat restraint retractor has a high level of load limiting as a default with a low level of load limiting being selectable during an impact. Another advantage of the present invention is that the selectable load limiting seat restraint retractor has a load level response that starts high and ends lower, working in conjunction with the airbag to maximize performance for a mid sized occupant in a high severity impact.
Other objects, features, and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description taken in conjunction with the accompanying drawings.