When an engine rotation speed is lower than a reference rotation speed, first failure determination in which failure of a flow rate control valve is determined based on a pressure change of cooling water detected by a pressure sensor is executed, when a valve closing instruction to switch the flow rate control valve from an opened state to a closed state is output from a valve control device; and when an engine rotation speed is equal to or higher than the reference rotation speed, second failure determination in which failure of the flow rate control valve is determined based on a pressure change of cooling water detected by a pressure sensor is executed, when a valve opening instruction to switch the flow rate control valve from a closed state to an opened state is output from the valve control device.

In one implementation, a system for valve failure prediction includes a temperature engine to determine a temperature of a liquid exiting a cooling device, a flowrate engine to compare an actual flow rate of the liquid exiting the cooling device to a flow rate threshold, a prediction engine to determine when a valve of the cooling device is malfunctioning based on the comparison of the actual flow rate and the flow rate threshold, and a notification engine to notify a user when the valve of the cooling device is malfunctioning.

To estimate an engine cooling water temperature, four learned neural networks (150A, 150B, 150C, and 150D) are stored, in which weights are learned for the four states of whether the grille shutter (50) is opened and whether air blown by the blower (63) circulates through the air-conditioning use heater (65). The engine cooling water temperature is estimated using any one of the learned neural networks selected from among the four learned neural networks (150A, 150B, 150C, and 150D). An abnormality of the engine cooling water recirculation system is detected based on the estimated value of the engine cooling water temperature.

A failure diagnosis method of a coolant temperature sensor for a vehicle, may include determining, by a controller, whether or not it is in a flow stop state that stagnates the flow of coolant by a flow control valve; obtaining, by the controller, an engine outlet coolant model temperature when it is in the flow stop state; and diagnosing, by the controller, as a failure of an engine outlet-side outlet water temperature sensor when the coolant model temperature is equal to or greater than a reference temperature and the flow stop state is maintained by the flow control valve.

A control method of a coolant control valve unit that rotates a cam using torque of a motor and allowing a profile formed on the cam to push a rod to allow the valve formed on the rod to open/close a coolant passage, including steps of: rotating the cam by operating the motor; detecting a rotation position of the cam; determining a stuck state in which the cam or the motor is not rotated while the motor is operated; and performing an escape mode in which if it is determined that the cam or the motor is in the stuck state, the motor outputs a predetermined torque to the cam side in a predetermined rotation direction to escape the cam from the stuck state.

A thermostat misdiagnosis prevention method applied to an engine system of the present disclosure applies high speed/high load and low speed/low load, which are divided by a vehicle speed and an engine output detected from the engine system at an engine warm-up temperature of engine coolant, as monitoring conditions of a thermostat, and determines thermostat fail by primarily determining the thermostat fail with the engine coolant temperature of the engine coolant temperature and the outside air temperature detected from the engine system, then confirming a delay time with respect to the outside air temperature, and secondarily determining the thermostat fail with the engine coolant temperature in a monitoring ECU, thereby corresponding to the enhanced OBD together with preventing the misdiagnosis of the thermostat by the fail-safe according to the primary and secondary determinations.

A main valve unit is rotatably provided in a main valve accommodation space connected to a first opening portion. A fail-safe valve unit is provided in a fail-safe valve accommodation space connected to a second opening portion. The main valve unit controls flow rate of cooling water flowing from the first opening portion to a radiator via a main water passage formed in a housing depending on a rotational position thereof. The fail-safe valve unit is closed when temperature of the cooling water is lower than a predetermined value, to thereby block off flow of the cooling water to the radiator. The fail-safe valve unit is opened when the temperature of the cooling water is higher than the predetermined value, to thereby allow the flow of the cooling water to the radiator. Each of the first opening portion and the main valve accommodation space is fluidically separated from the second opening portion and the fail-safe valve accommodation space by a partitioning wall formed in the housing.

A coolant control valve unit includes a valve housing. The valve housing includes a first coolant supply passage and a second coolant supply passage, a coolant chamber in which coolant supplied through the first and second supply passages gathers, a first distribution passage and a second distribution passage being distributed from the coolant chamber to coolant components, and a bypass passage bypassing the first distribution passage. The coolant control valve unit also includes first and second valves disposed to open and close the first distribution passage and the second supply passage, a thermostat of a temperature sensitive type installed at the bypass and operating by a coolant temperature, a valve operator controlling movement of the first and second valves, respectively, and a wall formed at one side of the thermostat and in which a cooling passage is formed such that the coolant flows from the coolant supply passage to the second distribution passage.

An engine-controlling device includes a coolant passage, a radiator, and a control valve. A coolant discharged from a pump circulates through the coolant passage. The radiator cools the coolant. The control valve includes a first valve that adjusts a flow rate of the coolant to be introduced into the radiator and that includes a valve member driven by an electric actuator, a second valve that is arranged in parallel with the first valve and that includes a valve member that is opened in accordance with a pressure or a temperature, and a malfunction-diagnosing unit that detects a valve-stuck malfunction of the first valve. An output of the engine is limited to an output equal to or less than a limiting value determined on a basis of a maximum flow rate of the coolant introduced into the radiator from the second valve when the valve-stuck malfunction of the first valve occurs.

A control device for a vehicle includes a grille shutter ECU that is connected to a LIN communication line and controls driving of a grille shutter, and an engine ECU that is connected to the LIN communication line so as to be able to establish communication with the grille shutter ECU. In the case of detecting an abnormality in the communication, if a predetermine threshold time or more has elapsed since a start of the vehicle, and if cumulative time that a detection result of a vehicle speed sensor is equal to or more than a predetermined vehicle speed threshold value, is equal to or more than a cumulative threshold value, and a number of starts of the vehicle is equal to or more than a predetermined trip number, the engine ECU determines that the detected abnormality is a failure in the LIN communication.