Continuously variable drivetrain

Abstract

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;    a lever pivot coupled to the crank; and    a lever operably coupled to the crank, wherein the lever is configured to rotate less than 360 degrees about the lever pivot during a power phase of a stroke.    
   
   
       2 . The drivetrain of  claim 1 , wherein rotation of the crank causes rotation of the lever in the same direction.  
   
   
       3 . The drivetrain of  claim 1 , wherein the power phase of the stroke is continuously variable.  
   
   
       4 . The drivetrain of  claim 1 , further comprising at least one pulley attached to the lever.  
   
   
       5 . The drivetrain of  claim 1 , wherein the crank is configured to rotate less than 360 degrees during the power phase.  
   
   
       6 . The drivetrain of  claim 1 , further comprising at least one pulley attached to the crank.  
   
   
       7 . The drivetrain of  claim 1 , wherein the lever comprises a guide surface.  
   
   
       8 . The drivetrain of  claim 7 , further comprising a lever stop adapted to cooperate with the guide surface.  
   
   
       9 . The drivetrain of  claim 8 , wherein the lever stop causes the lever to rotate.  
   
   
       10 . The drivetrain of  claim 1 , wherein the crank is configured to, after the power phase, reverse a direction of rotation of the crank to enter into a return phase of the stroke.  
   
   
       11 . The drivetrain of  claim 1 , wherein the lever is configured to, after the power phase, reverse a direction of rotation of the lever to enter into a return phase of the stroke.  
   
   
       12 - 55 . (canceled)  
   
   
       56 . 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; and    a lever operably coupled to the crank via the lever pivot, the lever configured to rotate less than 360 degrees about the lever pivot during the power phase.    
   
   
       57 . The drivetrain of  claim 56 , wherein movement of the crank causes movement of the lever.  
   
   
       58 . The drivetrain of  claim 56 , wherein a rotation of the crank causes a rotation of the lever that is opposite in direction to the rotation of the crank.  
   
   
       59 . The drivetrain of  claim 56 , further comprising a crank pivot, the crank pivot forming an axis of rotation for the crank, and wherein the lever moves closer to the crank pivot from the beginning to the end of the power phase.  
   
   
       60 - 184 . (canceled)  
   
   
       185 . A method of transmitting mechanical power, the method comprising: 
 providing a drivetrain configured to exhibit a stroke having a power phase and a return phase;    applying a force in a reciprocating motion to foot pedals that are coupled to the drivetrain;    transferring the force via a crank to a drive pulley operably coupled to the crank, the crank configured to rotate less than 360 degrees;    wherein at the end of the power phase a leg of a user of the drivetrain is substantially straight; and    wherein at the start of the power phase the leg is bent at angle of no more than 68 degrees.    
   
   
       186 . The method of  claim 185 , wherein the crank is configured such that a distance between a foot pedal at the beginning of the power phase and a foot pedal at the end of the power phase is about 69% of a distance between a foot pedal at the beginning of the power phase of a conventional rotary stroke and a foot pedal at the end of the power phase of a conventional rotary stroke.  
   
   
       187 . The method of  claim 185 , further comprising providing a lever and operably coupling the lever to the crank, and wherein the lever rotates less than 360 degrees during the power phase of the stroke.  
   
   
       188 . The method of  claim 187 , wherein the lever comprises a guide surface.  
   
   
       189 . The method of  claim 188 , further comprising providing a lever stop, wherein the lever stop is configured to be in contact with the guide surface during the power phase of a stroke.