CONTROL METHOD OF INTERNAL COMBUSTION ENGINE AND CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

To improve accuracy in failure diagnosis of a variable valve mechanism.SOLUTION: An internal combustion engine 10 includes a hydraulically-driven intake air variable valve mechanism 41 and a hydraulically-driven exhaust variable valve mechanism 42 whose valve timings can be changed. The internal combustion engine 10 controls oil pressure of working fluid to predetermined first pressure P1 when holding the valve timing, and controls oil pressure of the working fluid to predetermined second pressure higher than the first pressure P1 when changing the valve timing. When the oil pressure of the working fluid increases to predetermined third pressure higher than the first pressure P1, change of the valve timing is permitted. Thereby, it is possible to suppress wrong diagnosis as a failure when the intake air variable valve mechanism 41 and the exhaust variable valve mechanism 42 do not start moving due to delay in response of the oil pressure at transient time, and accuracy can be improved in failure diagnosis of the intake air variable valve mechanism 41 and the exhaust variable valve mechanism 42.SELECTED DRAWING: Figure 2 【課題】可変動弁機構の故障診断の精度向上を図る。【解決手段】内燃機関１０は、バルブタイミングを可変可能な油圧駆動方式の吸気可変動弁機構４１及び排気可変動弁機構４２を有する。内燃機関１０は、バルブタイミングを保持する際には作動油の油圧を所定の第１圧力Ｐ１に制御し、バルブタイミングを変更する際には作動油の油圧を第１圧力Ｐ１よりも高い所定の第２圧力に制御する。作動油の油圧が第１圧力Ｐ１よりも高い所定の第３圧力まで上昇するとバルブタイミングの変更を許可する。これにより、過渡時において、吸気可変動弁機構４１及び排気可変動弁機構４２が油圧の応答遅れにより動き出さないことを故障と誤診断することを抑制でき、吸気可変動弁機構４１及び排気可変動弁機構４２の故障診断の精度を向上させることができる。【選択図】図２