| 摘要 |
A stepless variable stroke drive particularly suitable for a bicycle transmission has a crank driven input element comprising a carrier housing journaled for rotation on a spindle. Mounted within the carrier, journaled on individual axles, radially spaced to the spindle, are four planet gears which engage an output sun gear. Recessed into one side of each planet gear is a concentric channel whose outer circumference is constructed with ratchet teeth and whose inner circumference journals a crank ring having pawls for engaging the ratchet teeth. The ring also has a follower which engages a cylindrical cam channel fixed on and adjustable to various eccentricities relative to the spindle. As the carrier housing rotates, the crank ring follower engages the cam channel causing the crank rings to angularly oscillate at an amplitude proportional to the cam channel eccentricity. Sequential intermittent engagement of the crank ring pawls with the planet gear ratchet teeth during a portion of each carrier revolution drives the sun gear at a constant speed which is a multiple of the input speed dependent on the cam eccentricity. In another embodiment, the crank ring is eliminated and the planet gears each have a follower for engaging the eccentric cam channel. The carrier housing has slots for the planet gear axles which allow the planet gear to sequentially move to engage and disengage the sun gear for a selected portion of each planet gear's oscillation to accomplish a speed increase, decrease or reversal. Alternate manual and automatic controls are provided for both embodiments to adjust the cam channel eccentricity. |
