| CPC B60H 1/00878 (2013.01) [B60H 1/00821 (2013.01); B60K 11/02 (2013.01); B60Y 2300/42 (2013.01); F04D 25/022 (2013.01); F04D 27/004 (2013.01)] | 4 Claims |

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1. A cooling fan device configured to use a cooling fan coupled to an engine via a fan clutch to generate cooling air flow for a radiator, the cooling fan device comprising an electronic control unit configured to control an engagement rate of the fan clutch, wherein
the electronic control unit is configured to execute:
a first calculation process that calculates a coolant temperature requested engagement rate, the coolant temperature requested engagement rate being a requested value of the engagement rate in accordance with a cooling request for the engine coolant;
a second calculation process that calculates, as a first guard value, a value of the engagement rate at which a rotation speed of the cooling fan is a first upper limit rotation speed based on a vehicle speed; and
an upper limit guarding process that sets a value of the coolant temperature requested engagement rate to the first guard value when a calculated value of the coolant temperature requested engagement rate in the first calculation process exceeds the first guard value,
thereby controlling the engagement rate based on a value of the coolant temperature requested engagement rate after being subjected to the upper limit guarding process, and
the first upper limit rotation speed is set to a lower speed when the vehicle speed is relatively low than when the vehicle speed is relatively high.
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