The present invention relates to safety belts for a passenger transport vehicle, especially a land vehicle and its subject is, more particularly, a retention device for a safety belt band of manually adjustable position and intended to be fastened to a structure.
As is known, for safety reasons, passenger transport vehicles are conventionally provided with seats equipped with a safety belt. This is true, for example, of aircraft and motor vehicles.
Where motor vehicles are concerned, safety belts with two or three anchoring points are conventionally used. When a safety belt with three anchoring points is used, the band comprises a pelvic strand and a pectoral strand which passes across the wearer's chest in the manner of a shoulder belt.
When a safety belt of this latter type is used, the pectoral strand occupies a position relative to its wearer which depends both on his build, the geometry of the vehicle and the seat and also on the state of fatigue of the latter. Under these conditions, in some cases, the pectoral strand can be level with the wearer's neck. It will therefore be appreciated that, in the event of a violent collision, since the safety belt is immobilized under the control of an inertia detector, the passenger's body is flown violently forwards and his neck encounters the band which can then behave no longer as a safety means, but as an especially dangerous object. In fact, in some collisions, it has been possible to find serious lesions of the neck caused by the safety belt and, more particularly, its pectoral strand.
Consequently, there has already been a proposal to ensure that the upper fastening point of the pectoral strand is of adjustable position, in order to allow for the wearer's build in comparison with the configuration of the vehicle.
Various devices have already been proposed. They are very often of such a configuration that the upper fastening point of the pectoral strand can occupy multiple positions within a range, the extent of which takes into account the extreme builds of a population in comparison with its average build.
These devices which are sometimes motorized are extremely complicated. They often resort to screw-and-nut mechanisms which thus make it possible to vary progressively the position of the upper fastening point of the pectoral strand.
Other embodiments make use of pawls and holes, relative to which movable-carriage mechanisms are shifted.
Other alternative embodiments utilize locking mechanisms equipped with a latch and with a keeper.
It will therefore be appreciated that all these devices are complicated and therefore unreliable and of relatively high cost.