Crankshaft apparatus

A crankshaft apparatus in an internal combustion engine or a compressor havng a piston arranged to reciprocate within a cylinder to act on a fluid medium within a chamber at one end of the piston, said crankshaft apparatus including the combination of:

• a shaft member carried by bearing supports for rotation about an axis perpendicular to reciprocation of said piston the cylinder at the end thereof opposite said chamber,
• a cam plate defining a cam surface secured to said shaft member for rotation thereof,
• two equal diameter follower rollers engaging said cam surface at diametrically-opposite points to rotate said cam, and
• means supporting said follower rollers to maintain the axes of the follower rollers generally parallel with the rotational axis of said shaft member while interconnecting said rollers with said piston, each rotational axis of the follower rollers being spaced by said cam surface from the rotational axis of said shaft member according to the polar equation:
• R=r+1/2S sin (.theta.)+1/2S' sin 3(.theta.+a)+1/2S" sin 5(.theta.+b)+1/2S'" sin 9(.theta.+c)+1/2S"" sin 15(.theta.+d)+1/2S""' sin 45(.theta.+e)
• where:
• R is the radial distance between the rotational axis of the shaft member and a follower member at angle .theta.,
• r is the average displacement radius of the axis of the follower roller,
• S, S', S", S'", S"" and S""' are radial variations in the same surface with S not equal to zero and having the greatest absolute value,
• a, b, c, d and e are fixed phase angles with any value of .+-. from 0.degree. to 180.degree., and
• .theta. is the angular displacement of a reference mark on the cam to the center line of reciprocating motion of the follower rollers.