JP2004504201A5 - - Google Patents

Description

[0005]
Detailed Description of the Invention Figures 1 to 4 show the main elements of a seat belt retractor incorporating the present invention. The seat belt retractor 50 comprises a U-shaped frame 52 having openings 52a, 52b for supporting the spool and locking subassembly 54. These openings act as bearings. The spool and locking subassembly comprises a spool 56, a torsion bar 58 and a locking mechanism 60. One end 62 of the torsion bar 58 includes a plurality of splines 64 that mesh to transmit power to a plurality of splines 66 formed on the torsion bar (in a known manner). The torsion bar extension 68 is received in the spring arbor 70 and biased by a rewind spring 72. The other end 74 which is the reaction end of the torsion bar 58 is fixed to the wheel lock mechanism 60. The wheel lock mechanism 60 has a keyway aperture 80 which receives a spline 82 formed on the end 74 of the torsion bar. The mechanism rotationally couples the torsion bar and the locking mechanism 60. The locking mechanism and the torsion bar are axially fixed by swaging together these parts. The torsion bar 58 further includes an additional extension 84 which rotates with the spool prior to actuation of the torsion bar and which serves as part of the known type web sensor 86 schematically illustrated. Locking mechanism 60 has a ratchet wheel 86 that defines a cavity 88. The various parts of the web sensor, such as the web sensing pawl, are disposed within a cavity 88 (also illustrated in FIG. 4) formed by the ratchet wheel. A lock wheel 92 having a plurality of teeth 94 is fixed to the body 90 of the lock mechanism. A lock pawl 96, shown schematically, is rotatably mounted to the frame and engages with one or more teeth 94 of the lock wheel when the web sensor or vehicle sensor 98 operates in a known manner. As is known in the prior art, many seat belt retractors include a lock ring (not shown) that is rotatable relative to the shaft of the retractor (in this case, the torsion bar). The lock ring is coupled to the shaft of the winding device by actuation of a web sensor or cooperative vehicle sensor. This action causes the lock ring to be rotated slightly and in that action the lock pawl moves into engagement with the lock wheel. The web sensor has an inertial disk loosely attached to the extension 84 and a web sensor pawl (not shown) rotatably attached to the pin 87 of the ratchet wheel 86, the ratchet wheel 86 taking up the winding device In response to the rapid extension of the seat belt from the spool of the seat belt to mesh with the teeth formed at intervals close to the lock ring, thereby coupling the lock ring to the pawl, and the shaft of the winding device Bond to The vehicle sensor 98, which can be supported on the lock ring, also has a vehicle sensor pawl 98a which is moved by the movable mass (not shown) to the actuated position when the vehicle is subjected to a rapid deceleration. In the actuated position, the vehicle sensor pawl 98a meshes with the teeth 86a of the ratchet wheel 86, thereby coupling the lock ring to the shaft of the take-up device.

[0010]
The trace of FIG. 5 shows test data, in particular the belt force as a function of time (representing belt stretch). Trajectory 20 is comparative test data for a similar seat belt retractor that does not have slots and pins.