INTERNAL COMBUSTION ENGINE SYSTEM AND CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE SYSTEM

PROBLEM TO BE SOLVED: To suppress deterioration of combustion stability in a deceleration state during EGR control.SOLUTION: An internal combustion engine system 100 includes: a first intake passage 2; a first exhaust passage 3; a throttle chamber 4; an exhaust recirculation passage 8 for communicating a downstream side of a turbine 5B with an upstream side of a compressor 5A; an exhaust recirculation amount control valve 10; and a second intake passage 11 for communicating a downstream side of the throttle chamber 4 with an upstream side of a merging portion with the exhaust recirculation passage 8 of the first intake passage 2. An intake throttle valve 12 is disposed upstream of a merging portion with the second intake passage 11 upstream of the merging portion with the exhaust recirculation passage 8 in the first intake passage 2, and a valve 13 is disposed in the second intake passage 11. A control section 20 controls the throttle chamber 4 in the closing direction when decrease amount of a required exhaust recirculation rate reaches predetermined amount or more, and opens the valve 13 when inner pressure of the first intake passage 2 downstream of the throttle chamber 4 becomes lower than that of the second intake passage 11.SELECTED DRAWING: Figure 1 【課題】ＥＧＲ制御中の減速状態における燃焼安定度の悪化を抑制する。【解決手段】内燃機関システム１００は、第１吸気通路２と第１排気通路３とスロットルチャンバ４と、タービン５Ｂの下流側とコンプレッサ５Ａの上流側とを連通する排気再循環通路８と、排気再循環量制御バルブ１０と、スロットルチャンバ４より下流側と第１吸気通路２の排気再循環通路８との合流部より上流側とを連通する第２吸気通路１１とを備える。第１吸気通路２の、排気再循環通路８との合流部より上流側の第２吸気通路１１との合流部より上流側には吸気絞り弁１２が、第２吸気通路１１には弁１３が配置される。そして、制御部２０は要求排気再循環率の減少量が所定量以上になったらスロットルチャンバ４を閉方向に制御するとともに、スロットルチャンバ４より下流側の第１吸気通路２の内圧が第２吸気通路１１の内圧より低くなった場合に弁１３を開弁する。【選択図】図１