The present disclosure provides a method and system, for controlling a coolant circulating in an engine, including: selecting a reference inlet temperature for a coolant flowing through a coolant inlet of an engine; controlling an open rate of the coolant control valve unit based on the reference inlet temperature; sensing an actual inlet temperature of the coolant flowing through the coolant inlet of the engine; sensing an actual outlet temperature of a coolant flowing through a coolant outlet of the engine; calculating a difference value between the actual inlet temperature and the actual outlet temperature; and varying the reference inlet temperature according to the difference value.

Models that employ both measurable engine parameters as well as predictable engine parameters may be used to determine when a thermostat is malfunctioning before the thermostat malfunction results in an engine breakdown. Particular models may be used to provide an estimated coolant temperature and an estimated thermostat position. The estimated coolant temperature can be compared to an actual measured engine coolant temperature. The estimated thermostat position can be evaluated with respect to what the thermostat position should be given a particular engine coolant temperature. In some cases, comparison between a healthy model and a faulty model may be used to ascertain thermostat health.

A cooling system for vehicles and a control method thereof improves indoor heating performance and fuel efficiency by controlling a flow rate of a coolant passing through a heater core together with an EGR cooler. A coolant having an increased temperature is first supplied to the heater core side through a flow stagnancy control to rapidly increase the temperature of the coolant flowing in the heater core, thereby improving heating performance. A warm-up feature is improved through an exhaust heat recovery function by a heat exchange between the exhaust gas and the coolant in the EGR cooler, thereby improving efficiency of fuel.

An engine cooling system has a coolant control valve unit and includes a cylinder head disposed on a cylinder block. The coolant control valve unit is configured to receive coolant from a coolant outlet side of the cylinder head to control coolant distributed to a heater and a radiator and to control coolant exhausted from the cylinder block. A control unit is configured to determine a heating priority mode according to operation conditions and to substantially open a first coolant passage corresponding to the heater by controlling the coolant control valve unit in the heating priority mode.

An engine cooling system having an EGR cooler is disclosed. The system includes a cylinder head provided on a cylinder block, a coolant pump that pumps a coolant to a coolant inlet side of the cylinder block, an EGR cooler that is branched from a coolant line between the coolant pump and the cylinder block, and is provided in a circulation line through which a coolant is recirculated to an inlet of the coolant pump, and a coolant control valve unit that is provided in a coolant output side of the cylinder head to receive a coolant exhausted from the cylinder head and a coolant exhausted from the cylinder block and controls coolants distributed to coolant parts.

A coolant circuit of an engine cooling apparatus includes a first passage where coolant flows through a radiator and a second passage where coolant flows without passing through the radiator. A coolant control valve controls a first passage flow rate Frad and a second passage flow rate Fsec. An outlet coolant temperature sensor detects an outlet coolant temperature Tout, which is a coolant temperature before a branching point of the first passage and the second passage. An inlet coolant temperature sensor detects an inlet coolant temperature Tin, which is a coolant temperature after a merging point of the first passage and the second passage. A coolant temperature estimator calculates a radiator coolant temperature Trad, which is a coolant temperature at a coolant exit of the radiator, when the first passage flow rate Frad is greater than or equal to a specified flow rate using equation (1).

[00001]$\begin{array}{cc}\mathrm{Trad}=\mathrm{Tin}-\left(\mathrm{Tout}-\mathrm{Tin}\right)\frac{\mathrm{Fsec}}{\mathrm{Frad}}& \left(1\right)\end{array}$

A vehicle propulsion system includes a prime mover having a coolant inlet and a coolant outlet, a coolant control valve having a valve inlet in communication with the prime mover coolant outlet, a first valve outlet, and a second valve outlet, a bypass flow path in communication with first valve outlet and the prime mover coolant inlet, a heat exchange flow path in communication with the second valve outlet and the prime mover inlet, a heat exchanger in the heat exchange flow path, a first temperature sensor in the bypass flow path for generating a first temperature signal, a second temperature sensor in the heat exchange flow path for generating a second temperature signal, and a controller for providing a coolant control valve command signal to the coolant control valve, using a normalized gain coefficient.

A thermal controller for automotive applications. A thermal controller in an aspect of the present disclosure includes a valve, a motor coupled to the valve, a temperature sensor, flow rate sensor, heater/cooler element, and a controller, coupled to the temperature sensor, flow rate sensor and the motor, in which the controller alters volume and temperature of fluid flow through the valve by turning the motor based on inputs from the temperature sensor.

A pressure relief valve is opened from a first time to a second time for the purpose of reducing the pressure in the gas phase in a gas-liquid separator. A first water pump (WP) is driven at a third time and a fourth time. The third time and fourth time correspond to timings at which a difference between a boiling temperature and an actual temperature becomes equal to or greater than a predetermined temperature. Since liquid-phase coolant in a catch tank can be fed to another water pump by driving the first WP, the actual temperature of the liquid-phase coolant immediately upstream of the other water pump can be lowered. It is thus possible to prevent intense boiling of the liquid-phase coolant immediately upstream of the other water pump.

A coolant temperature sensor abnormality determination device includes a determination unit configured to determine whether or not two coolant temperature sensors, which are configured to detect the temperature of the coolant, have an abnormality. The determination unit has a determination permission condition under which a reference temperature is set to an estimated temperature of a present time point and the estimated temperature is then changed from the reference temperature by a determination temperature. The determination unit is configured to determine, when the determination permission condition is satisfied, that the two coolant temperature sensors are functioning normally if a discrepancy between detection values of the two coolant temperature sensors is less than a normal temperature that is less than or equal to the determination temperature.