Engine reciprocative rotating mechanism and method for manufacturing the same

An engine reciprocative rotation mechanism, comprising:

• a piston reciprocating in a cylinder;
• a connecting rod connecting the piston and a crankshaft together;
• a piston pin connecting the piston and the connecting rod together, and having a through hole;
• a first dynamic vibration absorber provided to the piston or the connecting rod, and configured to reduce a vibration level, which is generated during an operation of the engine, at a first resonance frequency;
• and
• a second dynamic vibration absorber provided to the piston or the connecting rod, and configured to reduce a vibration level, which is generated during the operation of the engine, at a second resonance frequency higher than the first resonance frequency, wherein
• the first dynamic vibration absorber and the second dynamic vibration absorber are comprised of a damper which is provided in the through hole of the piston pin,
• the damper includes
• a fixture fixed to the through hole,
• a first body constituting the first dynamic vibration absorber,
• a first arm constituting the first dynamic vibration absorber, connecting the fixture and the first body, and having a smaller diameter than the first body,
• a second body constituting the second dynamic vibration absorber, and
• a second arm constituting the second dynamic vibration absorber, connecting the fixture and the second body, and having a smaller diameter than the second body,
• the second dynamic vibration absorber is higher in resonance frequency than the first dynamic vibration absorber, and
• a mass of the first body, a spring constant of the first arm, a mass of the second body, and a spring constant of the second arm are configured such that at least one of the resonance frequency of the first dynamic vibration absorber or the resonance frequency of the second dynamic vibration absorber differs from associated at least one of the first resonance frequency or the second resonance frequency, and a peak frequency of antiresonance occurring in a higher frequency region of the first dynamic vibration absorber than the resonance frequency of the first dynamic vibration absorber is substantially different from that of antiresonance occurring in a lower frequency region of the second dynamic vibration absorber than the resonance frequency of the second dynamic vibration absorber.