As the upper link where one end is concatenated to the piston pin

摘要

PROBLEM TO BE SOLVED: To reduce the energy loss due to the piston thrust load in a dual link type variable compression ratio mechanism.;SOLUTION: The variable compression ratio mechanism is equipped with an upper link 3 coupled with a piston 9, a lower link 4 coupled with the upper link 3 and also coupled with a crank pin 5 on a crank shaft 12, and a control link 7 to couple the lower link 4 with an eccentric cam 8 and restrict the degree of freedom of the lower link 4. The position of the upper dead point, and accordingly the compression ratio, changes depending upon the rotational position of the eccentric cam 8. The connecting point A is set so as to lie on the left in figure of the line segment PP-CP tying the center of piston pin PP to the center of crank pin CP in case the crank shaft 12 rorates in the direction of arrow ω, and the control link 7 is arranged on the side opposite thereto. The upper link 3 approaches the vertical positioning when the combustion load thereafter enlarges compared with the piston upper dead point.;COPYRIGHT: (C)2002,JPO