Seatbelt pretensioning retractor assembly including a gas release opening

A seatbelt pretensioning retractor assembly for use in a passenger vehicle, the seatbelt pretensioning retractor assembly comprising:

• a housing adapted for being mounted to a vehicle structure and having an interior cavity;
• a tube having an arcuate and curved shape having a first end for fluid communication with a gas generator and a second end in fluid communication with the interior cavity of the housing;
• a sprocket rotatably mounted to the housing and fixedly coupled to a spindle adapted for taking up seatbelt webbing during pretensioning, wherein the sprocket has a plurality of vanes;
• a driving element comprising a polymer rod configured to extend in a longitudinal direction and having a recessed portion defining a recess that extends generally in the longitudinal direction, wherein the polymer rod is disposed within the tube and is translatable through the tube in a first direction towards the sprocket in response to an actuation by the gas generator;
• a stopper coupled to an end portion of the polymer rod;
• and
• a seal member disposed between the gas generator and the polymer rod, wherein the tube includes a projection extending within the tube adjacent to an exit at the second end to define a constriction portion that has an opening dimension smaller than an inside dimension of adjacent portions of the tube, wherein the projection has an edge that defines at least part of an opening, and wherein the recess is aligned with the edge of the projection in the first direction and the edge is positioned to permit the recessed portion of the polymer rod to pass through the constriction portion while engaging the stopper and/or the end portion of the polymer rod to prevent the stopper from passing through the constriction portion.