Reciprocating internal combustion engine

A reciprocating internal combustion engine comprising:

• a first planetary gear mechanism including a first ring gear being an internal gear, a first carrier being rotatably supported relative to the first ring gear, and a first planetary gear being rotatably supported relative to the first carrier and engaging with the first ring gear;
• a first crank member being connected to the first planetary gear in such a way as to rotate integrally with the first planetary gear;
• a first piston member being connected to the first crank member in such a way as to be rotatable relative to the first crank member around a first input shaft center being set at a position separated from a first planetary shaft center being a rotating shaft center of the first planetary gear;
• a first counterrotating member rotating in an opposite direction to the first carrier at a same speed in interlocking relation with rotation of the first carrier;
• a second planetary gear mechanism including a second ring gear being an internal gear, a second carrier being rotatably supported relative to the second ring gear, and a second planetary gear being rotatably supported relative to the second carrier and engaging with the second ring gear;
• a second crank member being connected to the second planetary gear in such a way as to rotate integrally with the second planetary gear;
• a second piston member being connected to the second crank member in such a way as to be rotatable relative to the second crank member around a second input shaft center being set at a position separated from a second planetary shaft center being a rotating shaft center of the second planetary gear;
• a second counterrotating member rotating in an opposite direction to the second carrier at a same speed in interlocking relation with rotation of the second carrier;
• an interlocking mechanism causing the first counterrotating member and the second counterrotating member to interlock with each other in such a way that the first counterrotating member and the second counterrotating member rotate at a same speed;
• and
• an output member rotating in interlocking relation with the first carrier, the second carrier, the first counterrotating member, the second counterrotating member, and the interlocking mechanism.