Methods and systems are described for diagnosing a multiple speed, relay controlled engine cooling fan system. One method includes measuring the change in current drawn from a battery-alternator system when fan speed is modified. A degradation in cooling fan operation is flagged when measured current change differs from an expected change.

Methods and systems are described for diagnosing a multiple speed, relay controlled engine cooling fan system. One method includes measuring the change in current drawn from a battery-alternator system when fan speed is modified. A degradation in cooling fan operation is flagged when measured current change differs from an expected change.

A system according to the principles of the present disclosure includes a heat transfer rate module, a desired flow rate module, a flow rate adjustment module, and a pump control module. The heat transfer rate module determines a rate of heat transfer from an engine to coolant flowing through the engine based on a cylinder wall temperature and a measured coolant temperature. The desired flow rate module determines a desired rate of coolant flow through the engine based on the heat transfer rate. The flow rate adjustment module determines a coolant flow rate adjustment based on a desired coolant temperature and the measured coolant temperature. The pump control module controls a coolant pump to adjust an actual rate of coolant flow through the engine based on the desired coolant flow rate and the coolant flow rate adjustment.

A system includes a temperature estimation module and a pump control module. The temperature estimation module estimates a temperature of coolant flowing through an engine. The temperature estimation module estimates a temperature of a cylinder wall in the engine based on the estimated coolant temperature and a measured coolant temperature. The pump control module controls a coolant pump to adjust an actual rate of coolant flow through the engine based on the estimated cylinder wall temperature.

The present invention relates to a method for protecting an engine from short circuiting and wire failure of a fan clutch, and a device thereof wherein the method for protecting an engine comprises: a step of sensing the temperature of a coolant if a fan rotates at a set minimum rpm by the short circuiting and wire failure of a fan clutch; a step of comparing the sensed coolant temperature and a set danger temperature; and a step of defaulting if the sensed coolant temperature is lower than the set danger temperature and reducing the engine rpm if the sensed coolant temperature is equal to or higher than the set danger temperature according to a result of the comparison such that overheating of the engine can be prevented. The engine rpm is gradually lowered so as to protect the engine at a first stage if the fan operates at the minimum rpm due to the cable short cut and failure of the fan clutch, and the engine is forcedly stopped so as to protect the engine at a second stage if the overheating of the coolant is serious, thereby ensuring durability of the engine.

The present invention relates to a method for protecting an engine from short circuiting and wire failure of a fan clutch, and a device thereof wherein the method for protecting an engine comprises: a step of sensing the temperature of a coolant if a fan rotates at a set minimum rpm by the short circuiting and wire failure of a fan clutch; a step of comparing the sensed coolant temperature and a set danger temperature; and a step of defaulting if the sensed coolant temperature is lower than the set danger temperature and reducing the engine rpm if the sensed coolant temperature is equal to or higher than the set danger temperature according to a result of the comparison such that overheating of the engine can be prevented. The engine rpm is gradually lowered so as to protect the engine at a first stage if the fan operates at the minimum rpm due to the cable short cut and failure of the fan clutch, and the engine is forcedly stopped so as to protect the engine at a second stage if the overheating of the coolant is serious, thereby ensuring durability of the engine.

A water pump diagnosis device diagnoses a water pump that circulates a coolant that cools a cooling target. The water pump diagnosis device includes a temperature sensor and a diagnosis unit. The temperature sensor measures a temperature of a power semiconductor, which is a part of the cooling target. The diagnosis unit determines whether the water pump has failed based on a comparison between a temperature rise rate of the power semiconductor based on a temperature measured by the temperature sensor and a preset reference temperature rise rate.

A water pump diagnosis device diagnoses a water pump that circulates a coolant that cools a cooling target. The water pump diagnosis device includes a temperature sensor and a diagnosis unit. The temperature sensor measures a temperature of a power semiconductor, which is a part of the cooling target. The diagnosis unit determines whether the water pump has failed based on a comparison between a temperature rise rate of the power semiconductor based on a temperature measured by the temperature sensor and a preset reference temperature rise rate.