Flexible drive

Abstract

A variable rate frictional drive coupling is provided between a drive shaft and a driven member. The drive coupling will dampen torsional vibrations from the drive shaft and will transmit driving torque from said shaft to the driven member. The coupling comprises a cam and leaf springs positioned in such a way that as the shaft deflection increases, the load increases and the moment arm point of contact between the cam and the leaf springs changes such that no natural frequency is produced. The frictional forces between the leaves of the leaf spring change inversely to the spring force required to drive the driven member.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. A flexible drive having a housing, a .[.pair of shafts rotatably.]. .Iadd.drive shaft .Iaddend.rotatably mounted in said housing, .[.one of said shafts being rotatably driven,.]. cam means secured to said .[.rotatably drive.]. .Iadd.rotatable drive .Iaddend.shaft, elongate spring means in engagement with .[.a portion of the opposite sides of.]. .Iadd.said .Iaddend.cam means, gear means encircling said cam means and said spring means, .[.the end portions of.]. said spring means .Iadd.having end portions .Iaddend.seating in .[.the.]. .Iadd.an .Iaddend.inner surface of said gear means, .[.a.]. second gear means .[.carried by said other of said shafts, driven.]. .Iadd.mounted in said housing and meshing with said first gear means, .Iaddend.means .[.carried.]. .Iadd.driven .Iaddend.by said second gear means .[.and operatively connected with said second shaft whereby.]. .Iadd., .Iaddend.said .[.rotatably driven.]. .Iadd.rotatable drive .Iaddend.shaft rotates said .[.driven.]. means .Iadd.driven by said second gear means .Iaddend.through said cam means and spring means. 
     
     
       2. A flexible drive as claimed in claim 1 wherein said cam means is essentially .[.elliptical in shape.]. .Iadd.shaped like an ellipse.Iaddend., and said spring means are at least two elongate flat springs disposed in planes substantially parallel to each other and parallel to the major axis of said ellipse and contacting said cam means on the long sides of the ellipse. 
     
     
       3. A flexible drive as claimed in claim 1 wherein said spring means comprises a pair of springs, each spring having a plurality of leaves in contacting side-by-side relationship. .[.4. A flexible drive as claimed in 
     
     
        claim 1 wherein said shafts are disposed parallel to each other..]. 5. A flexible drive as claimed in claim 2 wherein means are provided on said .[.rotatably driven.]. .Iadd.rotatable drive .Iaddend.shaft for 
     
     
        frictionally locking said cam means to said shaft. 6. A flexible drive comprising a housing having a base, a .[.pair of shafts.]. .Iadd.shaft .Iaddend.in said housing .[., one of said shafts.]. extending through said base, said .[.one of said shafts.]. .Iadd.shaft .Iaddend.being .[.drive.]. .Iadd.a drive shaft .Iaddend.and receiving rotational and vibrational forces from a prime mover, cam means disposed inside said housing and secured to said .[.driven.]. .Iadd.drive .Iaddend.shaft for rotation therewith, elongate spring means in engagement with a portion of the opposite sides of .Iadd.the .Iaddend.cam means, a cylindrically-shaped gear means encircling said cam means and said elongate spring means and having gear teeth on the outer periphery thereof, and .[.end portions of.]. said spring means .Iadd.having end portions .Iaddend.seating in notches formed in the inner surface of said gear means, a mating set of gear teeth formed on .[.a.]. second gear means .[.carried by said other end of said shafts.]. .Iadd.rotatably mounted in said housing.Iaddend., and said second gear means drivingly connected to driven means associated with .[.said second shaft.]. .Iadd.the housing .Iaddend.whereby said drive shaft rotates said driven means through said cam means and spring means. 
     
     
           A flexible drive as claimed in claim 6 wherein said cam means is a truncated ellipse, and said spring means are at least two elongate flat springs disposed in planes parallel to each other and parallel to the major axis of said ellipse and contacting said cam means on the long sides of the ellipse. .[.8. A flexible drive as claimed in claim 6 wherein said pair of shafts are parallel to each other and are mounted in said base of said housing..]. .[.9. A flexible drive as claimed in claim 6 wherein said 
     
     
        pair of shafts are axially aligned with each other..]. 10. A flexible drive as claimed in claim 7 wherein a thrust washer is seated on said cam means and has a slot formed therein offset from the midportion thereof, a lock washer is seated on said shaft and has one .[.tan.]. .Iadd.tang .Iaddend.seated in said slot, and means having a second tang of said lock washer seated against a flat surface thereof and frictionally locking said thrust washer against said cam means and against a shoulder on said 
     
     
        .Iadd.drive .Iaddend.shaft. 11. A flexible drive as claimed in claim 7 wherein said spring means comprises a pair of springs, each spring having 
     
     
        a plurality of leaves in juxtaposed relationship. 12. In a governor drive having a base, a pair of shafts extending through said base and being disposed parallel to each other, .[.each.]. .Iadd.one .Iaddend.of said shafts having a .Iadd.first .Iaddend.gear meshing with .[.each.]. .Iadd.a second gear surrounding a portion of the .Iaddend.other .Iadd.of said shafts, said .Iaddend.one of said shafts being .[.driven.]. .Iadd.a drive shaft .Iaddend.and receiving rotational and vibrational forces from a prime mover, a pair of flyweights .[.carried.]. .Iadd.operatively driven .Iaddend.by the .Iadd.second .Iaddend.gear on said other shaft, cam .[.mean.]. .Iadd.means .Iaddend.carried by said .[.driven.]. .Iadd.drive .Iaddend.shaft for rotation therewith, elongate spring means seated in said .Iadd.first .Iaddend.gear on the .[.driven.]. .Iadd.drive .Iaddend.shaft and engaging with a portion of the .[.opposite sides of.]. cam means, whereby rotation of said .[.driven.]. .Iadd.drive .Iaddend.shaft will urge said cam means against said spring means to drive said .[.gear.]. .Iadd.first and second gears .Iaddend.and actuate said 
     
     
        flyweights. 13. In a governor drive as claimed in claim 12 wherein said cam means is .[.elliptical.]. in .Iadd.the .Iaddend.shape .Iadd.of an ellipse.Iaddend., and said spring means are at least two elongate flat springs disposed in planes substantially parallel to each other and parallel to the major axis of said ellipse and contacting said cam means 
     
     
        on the long sides of the ellipse. 14. In a governor drive as claimed in claim 13 wherein said spring means comprises a pair of springs, each spring having a plurality of leaves in side-by-side contact with each other. .Iadd. 15. A flexible drive having a housing with a rotatable drive shaft, cam means secured to said rotatable drive shaft, elongate spring means in engagement with said cam means, gear means encircling said cam means and said spring means, said spring means having end portions seating in an inner surface of said gear means, driven means carried by said housing and operatively connected with said gear means, said rotatable drive shaft rotating said driven means through said cam means and spring means. .Iaddend.