COOLING WATER FLOW RATE CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide a cooling water flow rate control device for an internal combustion engine that enables reduction of the possibility of deterioration of emissions and fuel economy even when high viscosity LLC is used and even at an ultralow temperature.SOLUTION: A cooling water flow rate control device for an internal combustion engine includes: a first circulation passage section 22 and the like formed by interposing an external device 32 and the like between an outlet section 13out of a cooling water passage 13 and a water pump 40; and a second circulation passage section 24 and the like formed by directly connecting the outlet section and the water pump with each other. An ECU 60 controls a cooling water control valve device 50, so that pressure loss when cooling water flows becomes smaller as detected kinematic viscosity of the cooling water increases, so that a passage area of the second circulation passage section is set to a value larger than zero and a passage area of the first circulation flow passage is set to zero when the kinematic viscosity is predetermined first kinematic viscosity and so that the passage area of the second circulation passage section is set to a maximum value and the passage area of the first circulation passage section is set to a value larger than zero when the kinematic viscosity is predetermined second kinematic viscosity larger than the first kinematic viscosity.SELECTED DRAWING: Figure 1 【課題】高粘度ＬＬＣが使用され、かつ、極低温であっても、エミッション及び燃費の悪化を招く可能性が小さい、内燃機関の冷却水流量制御装置を提供する。【解決手段】冷却水通路１３の出口部１３ｏｕｔとウォーターポンプ４０との間に外部装置３２等を介装した第１循環通路部２２等と、出口部とウォーターポンプを直接的に接続してなる第２循環通路部２４等とを備える。ＥＣＵ６０は、検出される冷却水の動粘度が高くなるほど冷却水が通流する際の圧力損失が小さくなり、且つ、動粘度が所定の第１動粘度である場合に第２循環通路部の通路面積がゼロよりも大きい値に設定されるとともに第１循環通路部の通路面積がゼロに設定され、動粘度が第１動粘度よりも大きい所定の第２動粘度である場合に第２循環通路部の通路面積がその最大値に設定されるとともに第１循環通路部の通路面積がゼロよりも大きい値に設定されるように冷却水制御弁装置５０を制御する。【選択図】図１