Tension relieving mechanism for a safety belt system

In a seat belt retractor for rewinding a seat belt, said retractor comprising:

• a housing defining an enclosure:
• a shaft extending through said housing and said enclosure and having a first and second end;
• a reel for said belt mounted on said shaft in said enclosure;
• an emergency locking means for locking the belt retractor against protraction during rapid deceleration;
• means for retracting and rewinding said belt on said reel, said retracting means coupled to said first end to apply a first retracting force to said shaft and belt;
• said belt protractable from said reel and securable across an occupant at a first and taut position to apply said retraction force across said occupant;
• means for relieving at least some of said first retracting force applied by the belt onto the body of an occupant in a vehicle, said means for relieving operable between a disengaged position and an engaged position and operable to apply a second force to said shaft in a belt-protracting direction at said engaged position, which second force is less than said retracting first force, to reduce the effect of said retracting first force on the shaft and occupant at said engaged position, and said means for relieving having a ratchet wheel rotatably mounted on the shaft with a plurality of teeth on the circumference of an annulus defining a pocket;
• said means for relieving includes a coil spring positioned in said pocket and having a central passage, a first spring end, a second spring end and an arm at one of said first and second spring ends;
• said coil spring mounted on and frictionally engaging said second end of the shaft and being tightly wound on said shaft at belt protraction and applying said second force on said shaft in opposition to said retraction force at said tension-relieving means engaged position;
• and
• said coil-spring arm extending generally radially outward from said longitudinal axis to engage said annulus and couple said shaft to said ratchet wheel.

A tension-relieving means for a seat belt retractor assembly, which assembly has a belt, a housing with an enclosure,

• a shaft extending through said housing and enclosure and having a first end and a second end,
• means for retracting said belt mounted on one of said shaft first and second ends to rewind said belt in said enclosure;
• said tension-relieving means comprising:
• a casing having an inner wall and a sidewall cooperating to define a cavity;
• a central post extending from said inner wall and a stub shaft extending from said inner wall and normal to said inner wall adjacent said sidewall;
• an annular projection mounted on said inner wall around said central post;
• an unlocking disc with a periphery, a generally central throughbore and a peripheral slot which disc is mountable and rotatable on said annular projection for rotation between tension-relieving means disengaged and engaged positions;
• a lock control disc with a second periphery, a peripheral notch and a central passage generally alignable with said unlocking disc throughbore, said notch and unlocking disc slot alignable at said tension-relieving-means engaged position;
• a ratchet wheel having a hub with an annular sidewall, a first end, and a second end, a base with a mounting aperture at said first end and a radially extending flange at the second end, an annulus extending away from said flange and said second end and having an inner surface and an outer surface, said inner surface having an inner-surface notch and defining a pocket, a plurality of ratchet teeth on said outer surface;
• a retaining washer with a mounting passage;
• said lock control disc mounted on said hub of the ratchet wheel, which hub extends through said washer passage and is rotatably mounted on said central post with said washer biasing said lock control disc into contact with said ratchet flange;
• a coil spring positionable in said ratchet wheel has a first spring end, a second spring end, and a longitudinal axis, which spring defines a passage for said other shaft end along said axis,
• an arm at one of said first and second spring ends radially extending from said longitudinal axis, and engageable with said notch in said ratchet wheel;
• a pawl having a follower stud and a throughbore for rotatable mounting on said stub shaft, said pawl stud is nested in said aligned unlocking disc slot and lock control disc notch at the engaged position and said pawl contacting said ratchet teeth to secure said ratchet wheel and coil spring from retractive rotation with said shaft, which spring applies a frictional force against said shaft to reduce the retractive force on said belt and occupant at said engaged position.

In a seat belt retractor for rewinding a seat belt, said retractor comprising:

• a housing defining an enclosure;
• a shaft having a first end and a second end, and extending through said housing and enclosure;
• an emergency locking means for locking the belt against protraction upon detection of a predetermined acceleration;
• a first spring coupled to one of said first and second ends to bias said shaft and belt to a rewound and reference state;
• means for relieving at least some of the bias applied by said first spring to the belt and onto the body of an occupant in a vehicle, said relieving means having a ratchet wheel mounted on the shaft, a pawl pivotally mounted to move between a first position engageable with the ratchet wheel to stop rotation of the ratchet wheel with rotation of the shaft and a second position clear of the ratchet wheel in which the ratchet wheel rotates with the shaft, a second spring mounted on the other of said shaft first and second ends, which second spring is coupled to the ratchet wheel and frictionally retained on said shaft and operable between a first and expanded position at belt retraction and a second and contracted position during belt protraction, and means to selectively engage the pawl with the ratchet wheel to restrain said ratchet wheel and said second spring to provide a frictional force on said shaft at a tension-relieving mode in an opposed direction to rewinding of said shaft and belt to allow said shaft to slip and reduce the rewinding force on said belt and occupant.