Winding – tensioning – or guiding – Strand tensioning device – Tortuous course
Patent
1977-02-02
1978-07-11
Hornsby, Harvey C.
Winding, tensioning, or guiding
Strand tensioning device
Tortuous course
2421074R, A62B 3502, B65H 7548
Patent
active
040996832
ABSTRACT:
A safety belt retracting mechanism having constant pull includes a rotatable spool for storing the belt inside a housing. A conventional, positive coefficient of force spring inside the housing applies a retracting force to the spool and belt as the belt is pulled by the occupant. The spring is coupled between the housing and spool through a variable gear ratio gear train having a negative coefficient of force transfer characteristic. The negative transfer characteristic of the gear train compensates for the positive characteristic of the spring to provide constant pull to the belt between fully retracted and fully protracted belt positions. Three embodiments of the invention are disclosed. In one embodiment, the changing gear ratio is produced by a pair of oppositely oriented cone gears connected respectively to the spring and to a spindle supporting the belt spool. The cone gears are coupled together with a traversing pinion that lowers the force gear ratio of the cones as the belt is protracted by the occupant. In another embodiment, an approximately semicircular sector gear is mounted eccentrically on a shaft whereby the effective radius of the sector gear varies as a function of sector angle. The spindle is coupled to the spring (1) through a small radius portion of the sector gear when the belt is fully retracted, and (2) through progressively larger radius portions as the belt is protracted by the occupant providing the changing gear ratio. In a third embodiment, the gear train includes a pair of enmeshing sector gears and a number of intermediate spur gears. Each of the sector gears has an elliptical surface portion. When the belt is in a fully retracted position, the sector gears are oriented with the major axes thereof coincident to each other. As the belt is protracted, the enmeshing sector gears are each rotated by a maximum of 90.degree.. Output shafts are attached to the sector gears at corresponding sides thereof and on the major axes. A continuously decreasing gear ratio provided by the elliptical surface portions of the sector gears as the belt is protracted produces the negative coefficient of force transfer characteristic of the gear train.
REFERENCES:
patent: 3997126 (1976-12-01), Karlsson
patent: 4036449 (1977-07-01), Schreiber
Adams John
Stouffer Richard C.
Allied Chemical Corporation
Criss Roger H.
Henry Patrick L.
Hornsby Harvey C.
Jillions John M.
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