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 lever configured to rotate about an axis during a stroke of the drivetrain, the stroke comprising a power phase and a return phase;
a hook attached to the lever;
a lever stop configured to cooperate with the lever; and
a drive pulley operationally coupled to the lever.
2 . The drivetrain of claim 1 , wherein the lever and the drive pulley are configured such that a rotational speed of the drive pulley continuously increases during the power phase.
3 . The drivetrain of claim 1 , wherein the lever and the drive pulley are configured such that the drive pulley rotates faster during the last five degrees of the power phase than during the first five degrees of the power phase.
4 . The drivetrain of claim 1 , wherein the hook is configured to catch the lever stop at the end of the power phase.
5 . The drivetrain of claim 1 , wherein the hook is configured to catch the lever stop at the end of the return phase.
6 . The drivetrain of claim 1 , further comprising a crank operably coupled to the lever, wherein the crank is configured to have reciprocating motion.
7 . The drivetrain of claim 6 , wherein the lever is operably coupled to the crank.
8 . A drivetrain, comprising:
first and second rotatable cranks;
a crank pivot, wherein the cranks are configured to rotate less than 180 degrees about the crank pivot during a power phase of a stroke;
first and second lever pivots attached respectively to the first and second rotatable cranks;
first and second levers attached respectively to the first and second lever pivots, wherein the levers are configured to rotate less than 300 degrees during the power phase;
at least one crank pulley attached to each crank,
at least one lever stop operably coupled to each lever, and;
at least one drive pulley operably coupled to each crank.
9 . The drivetrain of claim 8 , wherein the cranks and the crank pulleys are configured such that a distance between the respective crank pulleys and crank pivots is adjustable.
10 . The drivetrain of claim 9 , wherein the cranks and the drive pulleys are configured such that the drive pulleys rotate faster when the crank pulleys are moved farther away from the crank pivot.
11 . The drivetrain of claim 8 , wherein the cranks, drive pulleys, and lever stops are configured such that the drive pulleys rotate faster when the cranks are moving away from the lever stops during the power phase.
12 . The drivetrain of claim 6 , further comprising a drive cable operably coupled to the drive pulley.
13 . The drivetrain of claim 12 , wherein the drive cable couples to the drive pulley, the crank pulley, and the lever.
14 . A drivetrain configured to convert human power to mechanical propulsive power, the drivetrain comprising:
a lever configured to rotate less than 360 degrees during a power phase of a stroke;
a hook attached to the lever; and
a first pulley attached to the lever.
15 . The drivetrain of claim 14 , further comprising a second pulley attached to the lever.
16 . The drivetrain of claim 15 , further comprising a crank operably coupled to the lever, wherein the crank is configured to move in reciprocating motion.
17 . The drivetrain of claim 16 , further comprising a lever pivot located on the lever.
18 . The drivetrain of claim 17 , wherein the lever pivot is operably coupled to the crank.
19 . The drivetrain of claim 14 , further comprising a lever stop operably coupled to the lever.
20 . The drivetrain of claim 19 , wherein the hook is configured to engage the lever stop at the end of the power phase.