| 摘要 |
PURPOSE:To aim at improvements in a starting characteristic and stabilization in warming up, by forming the central part of a piston pin into a crank part, while installing a hydraulic cylinder in a pin boss, and making a compression ratio selectable in two steps. CONSTITUTION:The central part of a piston pin P is formed into a crank part 9 being eccentric from journal parts 7 and 8 at both sides. A first hydraulic cylinder Cy1 to tie the piston P down to a low compression ratio position and a second hydraulic cylinder Cy2 to tie the piston down to a high compression ratio position both are installed in each of pin bosses 3 and 4. Doing like this, the compression ratio is selected in two steps according to a state of engine driving, thus improvements in a starting characteristic and stabilization in warming-up both are promoted. |
