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:
two levers;
two lever pivots, each lever pivot attached to a respective lever, wherein each lever is configured to rotate less than 360 degrees about a respective lever pivot during a power phase of a stroke;
first and second lever pulleys attached to each lever;
two compound pulleys; and
two flexible tension members, each flexible member contacting a respective compound pulley, first lever pulley, and second lever pulley.
2 . The drivetrain of claim 1 , wherein the levers, lever pivots, lever pulleys, and compound pulleys are configured such that a first length of the flexible tension member released at the end of the power phase is greater than a second length of the flexible tension member released at the beginning of the power phase.
3 . The drivetrain of claim 1 , wherein the rate of change of the length of the flexible tension member released continuously increases throughout the power phase.
4 . The drivetrain of claim 1 , wherein the second pulley does not contact the flexible tension member at the beginning of the power phase.
5 . The drivetrain of claim 1 , wherein during the power phase the first pulleys contact the flexible tension members before the second pulleys contact the flexible tension members.
6 . The drivetrain of claim 1 , wherein the flexible tension members contact more of the first pulleys at the end than at the beginning of the power phase.
7 . A continuously variable drivetrain (CVD) comprising:
first and second foot pedals;
first and second cranks, wherein the first and second foot pedals couple, respectively, to the first and second cranks;
wherein the cranks are configured for reciprocating motion;
wherein the cranks rotate along an arc defined by a crank pivot point located at an end distal from the pedals;
a frame adapted to support the cranks;
first and second drive pulleys coupled, respectively, to the first and second cranks;
first and second crank pulleys coupled, respectively, to the first and second cranks, the crank pulleys positioned at a distance from the crank pivot point;
a first drive cable wrapped around the first drive pulley and the first crank pulley; and
a second drive cable wrapped around the second drive pulley and the second crank pulley.
8 . The CVD of claim 7 , wherein the frame comprises a support structure for a human powered vehicle or exercise equipment.
9 . The CVD of claim 7 , wherein a first end of the first drive cable terminates at the interior of the first drive pulley.
10 . The CVD of claim 9 , wherein a second end of the first drive cable attaches to the frame.
11 . The CVD of claim 7 , further comprising a dependent cable adapted to raise the first crank while the second crank is depressed.
12 . The CVD of claim 11 , wherein the dependent cable comprises a first and second dependent cable ends that couple, respectively, to the first and second cranks.
13 . The CVD of claim 12 , further comprising an idler pulley, and wherein the dependent cable wraps around the idler pulley.
14 . The CVD of claim 13 , wherein the idler pulley is positioned above the cranks such that the dependent cable is tensioned by the cranks.
15 . The CVD of claim 7 , wherein the frame comprises a bicycle frame, wherein the pedals are located near the rear of the bicycle frame, and further comprising a chest support located such that a user leans forward on the chest support.
16 . The CVD of claim 7 , wherein the crank pulleys are coupled to the cranks such that during a power phase of a stroke there is an increase in a speed at which the drive pulley rotates.
17 . The CVD of claim 7 , further comprising first and second compound pulleys coupled respectively to the first and second drive cables to thereby accelerate a ratio change of the CVD.
18 . The CVD of claim 7 , wherein depending on whether a stroke is in its power or return phase, the drive cable unwinds from the compound pulleys as the compound cable winds onto the compound pulleys.
19 . The CVD of claim 7 , further comprising first and second levers coupled respectively to the first and second cranks, wherein the levers couple to the cranks via lever pivots.
20 . The CVD of claim 19 , further comprising lever pulleys that couple at distal ends of the levers.
21 . The CVD of claim 20 , wherein a lever cable runs from the first compound pulley, around the first lever pulley, and terminates at the frame or other stationary structure.
22 . The CVD of claim 20 , wherein each of the levers contacts, respectively, a roller that causes the lever to swing and pull more cable at the end than at the beginning of a stroke.
23 . A scooter comprising:
a crank configured to pivot about a crank pivot, wherein the crank pivot is located behind a rear wheel axle of the scooter;
a drive pulley operably coupled to a rear wheel of the scooter;
a crank pulley coupled to the crank;
a foot pedal coupled to the crank near, in the vicinity of, or at the crank pulley; and
a compound pulley operably coupled to the crank pulley and to the drive pulley.
24 . The scooter of claim 23 , further comprising a drive cable that couples the compound pulley to the drive pulley.
25 . The scooter of claim 24 , further comprising a compound cable that couples the compound pulley to the crank pulley.