CONTINUOUSLY VARIABLE DRIVETRAIN
Drivetrains and frames for vehicles, equipment, machines, etc. Some embodiments of the drivetrains and frames are particularly suited for human powered machines, such as bicycles and exercise equipment. In some embodiments, a drivetrain includes a reciprocating crank coupled to a crank pivot. A lever couples to the crank via a lever pivot positioned on the crank. A lever stop cooperates with a lever guide surface to guide a motion of the lever as the lever pivots about the lever pivot. The lever and/or the crank are operably coupled to a drive pulley, idler pulley, and/or compound pulley. In some embodiments, a drive cable operably couples the lever and/or the crank to the drive pulley, idler pulley, and/or the compound pulley. In one embodiment, one or more pulleys couple to the lever's distal ends. In some embodiments, the drivetrain includes a wheel hub adapted to receive torque from the crank via a drive pulley.
1 . A drivetrain, comprising:
a crank configured to rotate less than 360 degrees during the power phase of a stroke;
a lever pivot coupled to the crank;
a drive pulley having a spiraling root;
a flexible tension member operably coupled to the crank and the drive pulley;
wherein a first end of the flexible tension member terminates at the root of the drive pulley, the flexible tension member is spirally wound on the drive pulley at the beginning of the power phase, and the flexible tension member unwinds from the drive pulley during the power phase.
2 . The drivetrain of claim 1 , wherein the flexible tension member unwinds from the drive pulley and thereby causes the drive pulley to rotate faster at the end than at the beginning of the power phase.
3 . The drivetrain of claim 1 , wherein, if a force applied to the crank is constant, a torque applied to the drive pulley continuously decreases during the power phase.
4 . The drivetrain of claim 1 , wherein the increase in a radius of the spiraling root is substantially equal to a diameter of the flexible tension member.
5 . The drivetrain of claim 1 , further comprising a compound pulley coupled to the crank.
6 . The drivetrain of claim 5 , wherein the compound pulley comprises two spiraling roots.
7 . The drivetrain of claim 6 , wherein a second end of the flexible tension member terminates at one of the spiraling roots of the compound pulley.
8 . The drivetrain of claim 7 , further comprising a second flexible tension member, a first end of the second flexible tension member terminating at second spiraling root of the compound pulley.
9 . A human powered vehicle, comprising:
a frame;
at least one wheel attached to the frame;
at least one crank, the crank configured to rotate less than 360 degrees during the power phase of a stroke, the crank operably coupled to the wheel;
wherein during the power phase a rotation of the crank causes a rotation of the wheel; and
wherein the power phase is continuously variable and causes the wheel to rotate more rapidly at the beginning than at the end of the power phase.
10 . The drivetrain of claim 9 , wherein shifting occurs automatically from changes in speed of the wheel and assuming a constant force produced by the user.
11 . A drivetrain comprising:
a crank configured to pivot about a crank pivot, the crank adapted to facilitate input of force to the crank in a reciprocating motion; and
a drive pulley operably coupled to the crank, the drive pulley adapted to receive and deliver torque.
12 . The drivetrain of claim 11 , further comprising a crank pulley coupled to the crank at an end distal from the crank pivot.
13 . The drivetrain of claim 11 , further comprising a flexible tension member coupling the crank to the drive pulley.
14 . The drivetrain of claim 12 , further comprising a flexible tension member coupling the crank pulley to the drive pulley.
15 . The drivetrain of claim 11 , further comprising a second crank, second crank pulley, second drive pulley, and second flexible tension member, wherein said second crank pulley couples to said second crank, and said second flexible tension member couples the second crank pulley to the second drive pulley.
16 . The drivetrain of claim 15 , further comprising a dependent cable that operationally couples the motions of the crank and the second crank.
17 . The drivetrain of claim 16 , further comprising a dependent pulley positioned such that the dependent cable wraps on the dependent pulley.
18 . The drivetrain of claim 12 , further comprising a compound pulley operably coupled to the drive pulley and the crank pulley.
19 . The drivetrain of claim 18 , further comprising a drive cable that couples the compound pulley to the drive pulley.
20 . The drivetrain of claim 19 , further comprising a compound cable that couples the compound pulley to the crank pulley.
21 . The drivetrain of claim 20 , wherein the drive cable starts at the drive pulley and terminates at the compound pulley.
22 . The drivetrain of claim 21 , wherein the compound cable starts at the compound pulley and terminates at a stationary structure.
23 . The drive train of claim 11 , further comprising a brake or generator operably coupled to the drive pulley.
24 . The drive train of claim 23 , further comprising a drive hub that couples the drive pulley to the brake or generator.
25 . The drive train of claim 24 , wherein the brake or generator comprises an annular flux disc coupled to the drive hub and a magnetic brake configured to cooperate with the annular flux disc.