Active Anti-Bunching D-Ring Seat Belt System

A motor vehicle seat belt system comprising:

• seat belt webbing having an upper and lower anchorage;
• a retractor engaging an end of the webbing at the upper or lower anchorage for allowing extraction and retraction of the webbing;
• a tongue engaging the seat belt webbing;
• a buckle engageable with the tongue to secure the seat belt webbing across an occupant;
• a D-ring rotatably mounted to a vertical adjustment unit which is in turn slidably mounted to a B-pillar of the motor vehicle, said D-ring being positioned on the belt webbing between the upper anchorage and the tongue, for positioning and guiding the webbing between the upper anchorage and the tongue;
• a locking pin engageable with the D-ring for restricting the range of backward rotation of the D-ring;
• an electric solenoid operatively connected to the locking pin;
• and
• a latching signal produced by the condition of the tongue and buckle being latched, which signal causes the solenoid to engage the locking pin.

A method of controlling the rotation of a D-ring in a seat belt system for a motor vehicle, comprising:

• providing a seat belt webbing having an upper and lower anchorage;
• engaging an end of the webbing at an upper or lower anchorage that allows extraction and retraction of the webbing;
• engaging the seat belt webbing with a tongue;
• providing a buckle engageable with the tongue to secure the seat belt webbing across an occupant;
• rotatably mounting the D-ring to a fixed member of the motor vehicle;
• positioning the D-ring on the belt webbing between the upper anchorage and the tongue;
• positioning and guiding the webbing through the D-ring;
• providing a locking mechanism engagable with the D-ring for restricting the range of backward rotation of the D-ring;
• and
• controlling the locking mechanism to periodically engage the locking mechanism.