Crank mechanism for the use in an in-line boxer engine

A crank mechanism for the use in an in-line boxer engine comprising:

• a pair of two diametrically opposed cylinders,
• a crankshaft,
• a piston for each of the diametrically opposed cylinder,
• a corresponding connecting rod for each of the diametrically opposed cylinder,
• whereas one of the connecting rods has a first piston connecting portion with a gudgeon pin bearing at one end and a single crankshaft bearing portion at the other end, and
• whereas the other connecting rod has a second piston connecting portion with a gudgeon pin bearing at one end and a forked crankshaft bearing portion at the other end that bifurcates into two spaced limbs, which surround the single crankshaft bearing portion with the two ends of said limbs,
• wherein the crankshaft has a cylindrical central middle crankpin affixed in a manner that its axis is eccentric and parallel offset relative to the longitudinal axis of the crankshaft, which central middle crankpin is directly adjoined on both of its sides by two cylindrical outer crankpins, which outer crankpins are eccentric and parallel offset relative to the longitudinal axis of the crankshaft such that the two outer crankpins are arranged on the same longitudinal axis and such that a connecting line starting perpendicularly from this outer crankpin longitudinal axis and crossing the eccentric longitudinal axis of the central middle crankpin would also intersect the longitudinal axis of the crankshaft,
• wherein a spacing between the two spaced limbs of the other connecting rod is equal to a sum of widths of the central middle crankpin and the two cylinder outer crankpins, and
• wherein the single crankshaft bearing portion as well as the forked crankshaft bearing portion have cylindrical inner bearing surfaces which are mounted on the respective crankpins.

A crank mechanism for the use in an in-line boxer engine comprising:

• a pair of two diametrically opposed cylinders,
• a crankshaft,
• a piston for each of the diametrically opposed cylinder,
• a corresponding connecting rod for each of the diametrically opposed cylinder,
• whereas one of the connecting rods has a first piston connecting portion with a gudgeon pin bearing at one end and a single crankshaft bearing portion at the other end, and
• whereas the other connecting rod has a second piston connecting portion with a gudgeon pin bearing at one end and a forked crankshaft bearing portion at the other end that bifurcates into two spaced limbs, which surround the single crankshaft bearing portion with the two ends of said limbs,
• wherein the crankshaft has a cylindrical central middle crankpin affixed in a manner that its axis is eccentric and parallel offset relative to the longitudinal axis of the crankshaft, which central middle crankpin is directly adjoined on both of its sides by two cylindrical outer crankpins, which outer crankpins are eccentric and parallel offset relative to the longitudinal axis of the crankshaft such that the two outer crankpins are arranged on the same longitudinal axis and such that a connecting line starting perpendicularly from this outer crankpin longitudinal axis and crossing the eccentric longitudinal axis of the central middle crankpin would also intersect the longitudinal axis of the crankshaft,
• wherein between the central crankpin and each adjoining outer crankpin is formed a cross-sectional area by overlapping partial side surface areas of the central crankpin and the respective adjoining outer crankpin, and
• wherein the single crankshaft bearing portion as well as the forked crankshaft bearing portion have cylindrical inner bearing surfaces which are mounted on the respective crankpins.