Seat belt retractor mechanism.

摘要

There is provided an improvement in a seat belt retractor mechanism of the type having a seat belt reel rotatably mounted in a support frame adapted to be asembled on a movable door of a vehicle, wherein the reel has at least on one end a generally circular ratchet plate for engaging a locking element movably mounted on the support frame between a first position allowing the reel to payout the belt freely and a second position engaging the ratchet plate to hold the reel against rotation to payout the seat belt. An inertia sensing element carried by the support frame shifts this locking element into the locked position upon being moved by inertia forces caused by rapid acceleration or deceleration of the vehicle to which the mechanism is mounted. In addition, an electromagnet is employed for increasing the amount of inertia force needed to move the inertia sensor element during such rapid changes in speed of the vehicle. This electromagnet is energized when the door is opened so that movement of the door itself by the occupant in entering or leaving the vehicle will not trip the sensor element. The improvement is the provision of a generally flat pole surface for the electromagnet and a generally flat keeper surface which are engaged in a generally coplanar relationship to cause the increased inertia force by magnetic attraction between the engaged surfaces upon energizing the electromagnet when the door is open. When the door is closed, there is no magnetic force between the engaging surfaces so that the inertia sensor element is moved by normal inertia forces.