Variable load limiting restraint retractor

A variable load limiting restraint retractor for a seat restraint system in a vehicle comprising:

• a housing for operative connection to vehicle structure;
• a take-up spool operatively connected to said housing and connected to a belt of a seat restraint system for winding and unwinding the belt;
• a rotatable shaft operatively connected to said take-up spool and said housing, said take-up spool being mounted on said shaft;
• a load limiting assembly operatively connected to said shaft for variably limiting load on the belt when the seat restraint system is in a buckled position;
• said load limiting assembly including a housing and a piston disposed within said housing for cooperating with said shaft;
• said housing including a cavity in one axial end and a passageway extending axially through another axial end and communicating with said cavity;
• and
• said piston comprising a piston portion disposed in said cavity and extending radially to a wall of said cavity to form a gap therebetween and a shaft portion extending axially from said piston portion and through said passageway.

A variable load limiting restraint retractor for a seat restraint system in a vehicle comprising:

• a retractor housing for operative connection to vehicle structure;
• a take-up spool operatively connect ed to said retractor housing and connected to a belt of a seat restraint system for winding and unwinding the belt;
• a rotatable shaft operatively connected to said take-up spool and said retractor housing, said take-up spool being mounted on said shaft;
• and
• a load limiting assembly including a rotatable piston operatively connected to said shaft for rotation with said shaft and for translating in a linear manner when an impact of the vehicle is sensed, either one of a magnetorheological (MR) fluid and electrorheological (ER) fluid cooperating with said piston, and an electrical coil for applying a magnetic field to said fluid to increase a viscosity of said fluid for variably limiting load on the belt during the impact.

A variable load limiting restraint retractor for a seat restraint system in a vehicle comprising:

• a retractor housing for operative connection to vehicle structure;
• a take-up spool operatively connected to said retractor housing and connected to a belt of a seat restraint system for winding and unwinding the belt;
• a rotatable shaft operatively connected to said take-up spool and said retractor housing, said take-up spool being mounted on said shaft;
• a load limiting assembly operatively connected to said shaft including either one of a magnetorheological (MR) fluid and electrorheological (ER) fluid for variably limiting load on the belt when the seat restraint system is in a buckled position;
• said load limiting assembly including a load limiting housing and a piston disposed within said load limiting housing for cooperating with said shaft, said fluid being disposed in a chamber of said load limiting housing and cooperating with said piston;
• said load limiting housing including a cavity in one axial end and a passageway extending axially through another axial end and communicating with said cavity;
• and
• said piston comprising a piston portion disposed in said cavity and extending radially to a wall of said cavity to form a gap therebetween and a shaft portion extending axially from said piston portion and through said passageway.

A seat restraint system for a vehicle comprising:

• a belt for restraining an occupant in the vehicle;
• a variable load limiting restraint retractor for operative connection to the vehicle and connected to said belt for winding and unwinding the belt;
• said variable load limiting restraint retractor comprising a retractor housing, a take-up spool operatively connected to said retractor housing and connected to said belt;
• a rotatable shaft operatively connected to said take-up spool;
• and
• a load limiting assembly including a rotatable piston operatively connected to said shaft for rotation with said shaft and for translating in a linear manner when an impact of the vehicle is sensed, a fluid cooperating with said piston, and an electrical coil for applying a magnetic field to said fluid to change a viscosity of said fluid for variably limiting load on the belt during the impact.