Vibration reducing system for internal combustion engine

A vibration reducing system of an internal combustion engine, comprising:

• a roll vibration system which generates a roll vibration of an engine main body, the roll vibration having a first vibration mode;
• and
• a rotational vibration system which generates a rotational vibration having a second vibration mode, and includes
• a crankshaft of the engine, for generating a rotational driving force;
• a main flywheel fixedly connected to said crankshaft;
• a driving force transmitting mechanism through which the rotational driving force of said crankshaft is transmitted, said driving force transmitting mechanism being movably secured to said engine main body, and
• an inertial mass member drivably connected to said driving force transmitting mechanism and rotatable to generate an inertial force upon receiving the rotational driving force transmitted through said driving force transmitting mechanism;
• means for causing said first and second vibration modes to make antiresonance at an antiresonance frequency;
• and
• means for adjusting said rotational vibration system to cause said antiresonance frequency to be generally coincident with one of frequencies which are obtained respectively by multiplying an engine-revolutional frequency at a predetermined engine speed by values each being represented by (a natural number/2).

A vibration reducing system of an internal combustion engine having a roll vibration system which generates a roll vibration of an engine main body, the roll vibration having a first vibration mode, said vibration reducing system comprising:

• a rotational vibration system which generates a rotational vibration having a second vibration mode which is coactive with the first vibration mode to occur an antiresonance, said rotational vibration system including
• a crankshaft of the engine, for generating a rotational driving force,
• a main flywheel fixedly connected to said crankshaft,
• a driving force transmitting mechanism through which the rotational driving force of said crankshaft is transmitted, said driving force transmitting mechanism being movably secured to said engine main body, and
• an inertial mass member drivably connected to said driving force transmitting mechanism and rotatable to generate an inertial force upon receiving the rotational driving force transmitted through said driving force transmitting mechanism;
• wherein said rotational vibration system is adjusted to cause said antiresonance frequency to be generally coincident with one of frequencies which are obtained respectively by multiplying an engine-revolutional frequency at a predetermined engine speed by values each being represented by (a natural number/2).

A method of reducing vibration in an internal combustion engine including a roll vibration system which generates a roll vibration of an engine main body, the roll vibration having a first vibration mode;

• and a rotational vibration system which generates a rotational vibration having a second vibration mode, and includes a crankshaft of the engine, for generating a rotational driving force;
• a main flywheel fixedly connected to said crankshaft;
• a driving force transmitting mechanism through which the rotational driving force of said crankshaft is transmitted, said driving force transmitting mechanism being movably secured to said engine main body, and an inertial mass member drivably connected to said driving force transmitting mechanism and rotatable to generate an inertial force upon receiving the rotational driving force transmitted through said driving force transmitting mechanism;
• said method comprising:
• causing said first and second vibration modes to coact so as to make antiresonance at an antiresonance frequency;
• and
• adjusting said rotational vibration system so as to cause said antiresonance frequency to be generally coincident with one of frequencies which are obtained respectively by multiplying an engine-revolutional frequency at a predetermined engine speed by values each being represented by (a natural number/2).