| 摘要 |
A piston crank mechanism of an internal combustion engine includes an upper link connected to a piston, a lower link connected to both the upper link and a crankpin, and a control link through which the lower link is linked to an eccentric cam of a control shaft to restrict the degree of freedom of the lower link. By varying the angular position of the eccentric cam with respect to the control-shaft axis, the center of oscillating motion of the control link varies, thus varying a compression ratio. The center of gravity of the lower link, determined by an equivalent inertia weight obtained by adding weights of connecting pins and weights of the upper-link boss-shaped end and the control-link boss-shaped end connected to the lower link via the respective connecting pins to the lower-link self-weight, is situated closer to the center of the crankpin.
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