Cooling device anomaly diagnosing apparatus

A cooling device anomaly diagnosing apparatus adapted for a cooling device in an internal combustion engine, wherein

• the cooling device includes
• an inner channel serving as a cooling channel located inside the internal combustion engine,
• an outer channel serving as a cooling channel located outside the internal combustion engine, the outer channel constituting, together with the inner channel, a loop path in which cooling water is circulated, and
• a regulating device capable of adjusting a cross-sectional area of a flow passage between the inner channel and the outer channel by an electronic control, the regulating device including a check valve configured to open when a pressure inside is higher than a pressure in the outer channel by an amount greater than or equal to a predetermined amount,
• the anomaly diagnosing apparatus is configured to execute
• an enlarging process of enlarging the cross-sectional area of the flow passage by operating the regulating device such that the cross-sectional area is larger in a case where a rotational speed of a crankshaft of the internal combustion engine is at a predetermined speed or higher than in a case where the rotational speed is lower than the predetermined speed,
• a rate calculating process of calculating, within a predetermined time period after startup of the internal combustion engine, a reference rate such that the reference rate has a larger value in a case where a fuel injection amount of the internal combustion engine is large than in a case where the fuel injection amount is small, the reference rate being a reference value for a rate of rise of a cooling water temperature in sections of the loop path other than the outer channel, and
• an anomaly determining process of determining, within the predetermined time period, that an anomaly is present in the check valve if a rate of rise of a detection value of a cooling water temperature in paths other than the outer channel is smaller than the reference rate, and
• the rate calculating process includes calculating the reference rate such that the reference value has a smaller value in a case where the enlarging process is executed than in a case where the enlarging process is not executed.