Reciprocating internal combustion engine

A multiple-link type reciprocating internal combustion engine, comprising:

• a piston movable through a stroke in the engine and having a piston pin;
• a crankshaft changing reciprocating motion of the piston into rotating motion and having a crank pin;
• a linkage comprising:
• an upper link connected to the piston pin;
• a lower link connecting the upper link to the crank pin;
• and
• a third link pivoted at one end to a body of the engine and connected at its other end to either of the upper and lower links to permit oscillating motion of the third link on the body of the engine;
• the upper link, the lower link, and the third link being dimensioned and laid out so that an amplitude of a second-order vibration component of a vibrating system of reciprocating motion of the piston, synchronizing rotary motion of the crankshaft, is generally equal to an amplitude of a third-order vibration component of the vibrating system.

The multiple-link type reciprocating internal combustion engine as claimed in claim 8, which further comprises a first connecting portion via which the lower link and the third link are connected to each other to permit relative rotation of the lower link about an axis of the first connecting portion and relative rotation of the third link about the axis of the first connecting portion and a second connecting portion via which the upper link and the lower link are connected to each other to permit relative rotation of the upper link about an axis of the second connecting portion and relative rotation of the lower link about the axis of the second connecting portion, and wherein the upper link, the lower link, and the third link are dimensioned and laid out, to satisfy a predetermined ratio

• L1:L2:L3:L4:L5:L6:XC:YC:x4≈1:2.4:2.65˜3.5:0.69:3.0˜3.4:3.3˜3.55:3.2˜3.55:−2˜−1.35:−1˜−0.6
• where L1 is a distance between the center of rotation of the crankshaft and an axis of the crank pin, L2 is a distance between the axis of the crank pin and an axis of the first connecting portion, L3 is a length of the third link, L4 is a distance between the axis of the crank pin and an axis of the second connecting portion, L5 is a distance between the axes of the first and second connecting portions, L6 is a length of the upper link, (XC, YC) are coordinates of the pivot of oscillating motion of the third link, and x4 is the x-coordinate of the trace line of reciprocating motion of the axis of the piston pin.

A multiple-link type reciprocating internal combustion engine, comprising:

• a piston movable through a stroke in the engine and having a piston pin;
• a crankshaft changing reciprocating motion of the piston into rotating motion and having a crank pin;
• a linkage comprising:
• an upper link connected to the piston pin;
• a lower link connecting the upper link to the crank pin;
• and
• a third link pivoted at one end to a body of the engine and connected at its other end to either of the upper and lower links to permit oscillating motion of the third link on the body of the engine;
• the upper link, the lower link, and the third link being dimensioned and laid out so that an amplitude of a second-order vibration component of a vibrating system of reciprocating motion of the piston, synchronizing rotary motion of the crankshaft, is reduced to below a predetermined threshold value, while realizing the same piston stroke and engine-cylinder height as a single-link type reciprocating internal combustion engine in which a piston pin and a crank pin are connected to each other by a single link.