COMPRESSION RATIO VARYING DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To improve the responsiveness in switching to a low compression ratio state by supplying the pressurized oil into the upper and lower liquid chambers formed between an outer piston and an inner piston through a check valve opened and closed by the hydraulic pressure before and behind the liquid chambers and discharging the pressurized oil in the upper liquid chamber outside when switching to the low compression ratio state is performed. CONSTITUTION:An inner piston 29 connected with a connecting rod 24 through a piston pin 23 is inserted in free sliding into an outer piston 21 having an annular part 22 screwed onto the lower part inner periphery, and the upper and lower liquid chambers 31 and 32 are formed in the upper and lower parts between the both. A working liquid chamber 25 is formed inside the piston pin 23, and the pressurized oil in the working liquid chamber 25 is supplied into an upper part liquid chamber 31 through a check valve 41, and the pressurized oil in the liquid chamber 31 can be discharged outside from a discharge part 27a through an opening/ closing valve 26 operated according to the variation of the oil pressure in the liquid chamber 31. Further, the upper liquid chamber 31 is allowed to communicate to the lower liquid chamber 31 through a check valve 42, and the pressurized oil in the liquid chamber 31 can be discharged outside through the oil passages 38a and 38b which are opened and closed by the opening/closing valve 26.