VARIABLE COMPRESSION RATIO UNIT OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To control a lubricating oil according to the compression ratio by using an actuator 31. SOLUTION: The variable compression ratio unit of an internal combustion engine is provided with a variable compression ratio mechanism comprising a multi-link piston-crank mechanism including an upper link, a lower link, a control link 11, and a control shaft 12 to change the oscillating support position of the control link 11. The compression ratio is changed by changing the position of an eccentric cam 13 of the control shaft 12 with the actuator 31. The actuator 31 has a screw mechanism in which a rod 33 axially advances and retreats by the rotation of a sleeve 34. A valve 51 to be a kind of a spool valve is formed between a plunger 33b of the rod 33, and a valve sleeve 52 of a casing 35. In a low compression ratio position equivalent to heavy load timing, the lubricating oil is positively supplied into a screw threaded portion of the actuator 31 by switching an oil passage of the valve 51 to prevent wear. COPYRIGHT: (C)2007,JPO&INPIT