Low stress engine for converting motion between reciprocating and rotational motion

Apparatus comprising:

• at least one reciprocating member confined to an axis of reciprocation;
• at least one rotating member with a crankpin;
• and
• at least one connector means connecting the reciprocating ember and the rotating member for converting at least one of rotating motion of the rotating member to reciprocating motion of the reciprocating member and reciprocating motion of the reciprocating member to rotating motion of the rotating member during each of a plurality of cycles of reciprocating motion of the reciprocating member from a first position to a second position and back to the first position;
• said connector means having a magnitude of translational momentum component in a direction perpendicular to the axis of reciprocation;
• said reciprocating member and said connector means having a magnitude of combined translational momentum component in a direction of reciprocation;
• said magnitude of translational momentum in a direction perpendicular to the axis of reciprocation being substantially equal and 90 degrees out of phase with said magnitude of combined translational momentum in the direction of reciprocation.

Apparatus comprising:

• at least one reciprocating member confined to an axis of reciprocation;
• at least one rotating member with a crankpin;
• at least one connector means connecting the reciprocating member and the rotating member for converting at least one of rotating motion of the rotating member to reciprocating motion of the reciprocating member and reciprocating motion of the reciprocating member to rotating motion of the rotating member during each of a plurality of cycles of reciprocating motion of the reciprocating member from a first position to a second position and back to the first position;
• said reciprocating member with a stroke length of travel substantially four times a crankpin offset;
• said connector means including at least one counterweight;
• a center of mass of said connector means with an at least one counterweight follows a path in the form of an ellipse with a major axis perpendicular to the axis of reciprocation;
• said at least one counterweight on said connector means sized and positioned to reduce but not eliminate the transfer of kinetic energy back and forth between said rotating member and said reciprocating member;
• said at least one counterweight on said connector means having a weight and location so that the kinetic energy transferred from said connector means to said reciprocating member and the energy from external forces on said reciprocating member combine to minimize the transfer of energy between said rotating member and said reciprocating member through midstroke.

Apparatus comprising:

• a crank having an axis of crank rotation and at least one crankpin;
• at least one reciprocating member confined to an axis of reciprocation;
• at least one connector means having a hole that receives said at least one crankpin, a cylindrical portion with a center of connector means rotation that is rotatably attached to said at least one reciprocating member, and at least one connector means counterweight;
• a secondary interface, between at least one of said crank and said at least one reciprocating member or between a housing confining said reciprocating member to reciprocation and said at least one connector means;
• a primary linkage between said at least one crankpin, said at least one connector means;
• and said at least one reciprocating member confined by the housing to reciprocation;
• said at least one crankpin having a crankpin center and a radius of crank rotation;
• said center of connector means rotation rotates around said at least one crankpin with equal but opposite angular velocity as said crankpin rotates around said crank axis whereby said center of connector means rotation reciprocates on the axis of reciprocation with a velocity twice that of said crankpin center in a direction of the axis of reciprocation;
• said reciprocating member reciprocates on the axis of reciprocation with a velocity twice that of said crankpin center in a direction of the axis of reciprocation;
• said reciprocating member has a stroke length of travel substantially four times the radius of crank rotation;
• said at least one connector means having a connector means counterweight with a resulting connector means center of mass located substantially on a line opposite said hole that receives said at least one crankpin as is said center of connector means rotation;
• the resulting velocity of said connector means center of mass is greatest at the top of a stroke and at the bottom of the stroke when the velocity of said at least one reciprocating member is least;
• the resulting velocity of said connector means center of mass is smallest at midstroke when the velocity of said at least one reciprocating member is greatest;
• the velocity, momentum, and energy of said connector means is greatest when that of said reciprocating member is least and the velocity, momentum, and energy of said connector means is least when that of said reciprocating member is greatest;
• kinetic energy is thus transferred back and forth from said connector means to said reciprocating member reducing the magnitude of the kinetic energy transferred back and forth from said crank to said reciprocating member through said secondary interface.