Thermostat leak detection

A cooling system controller configured to monitor performance of a cooling system that is configured to circulate engine coolant through an engine, the cooling system including a thermostat that controls engine coolant flow through a radiator, the controller configured to:

• receive an engine coolant temperature signal from an engine coolant temperature sensor;
• periodically execute a first model to generate a first thermostat position estimate to generate a plurality of first thermostat position estimates;
• perform a statistical analysis on the plurality of first thermostat position estimates in order to ascertain whether the thermostat is functioning appropriately;
• and
• output a warning signal when the thermostat is not functioning appropriately;
• wherein the thermostat is configured to:
• remain fully closed when the engine coolant temperature is below a first coolant temperature;
• be fully open when the engine coolant temperature is above a second coolant temperature;
• and
• be partially open when the engine coolant temperature is between the first coolant temperature and the second coolant temperature;
• and
• the controller is further configured to:
• a) when the engine coolant temperature is below the first coolant temperature, confirm that the first estimated thermostat position corresponds to fully closed;
• b) when the engine coolant temperature is above the second coolant temperature, confirm that the first estimated thermostat position corresponds to fully open;
• c) when the engine coolant temperature is between the first coolant temperature and the second coolant temperature, confirm that the first estimated thermostat position corresponds to a position between fully closed and fully open;
• and
• output a warning signal when the first estimated thermostat position does not correspond to what the thermostat position should be in any of a), b) or c).

A method of monitoring performance of a thermostat within an engine cooling system, the engine cooling system including a radiator and a coolant pump circulating coolant, the thermostat controlling flow of coolant through the radiator, the method comprising:

• receiving an engine coolant temperature signal from an engine coolant temperature sensor;
• supplying the engine coolant temperature signal to an Extended Kalman Filter (EKF), the EKF estimating an estimated engine coolant temperature and an estimated thermostat position;
• and
• comparing the estimated engine coolant temperature with an actual engine coolant temperature as indicated by the engine coolant temperature signal;
• wherein:
• when the estimated engine coolant temperature is within a temperature range centered on the actual engine coolant temperature, determining that the thermostat position is appropriate;
• and
• when the estimated engine coolant temperature is outside the temperature range centered on the actual engine coolant temperature, determining that the thermostat position is not appropriate.

A method of operating a cooling system controller configured to monitor performance of a cooling system that is configured to circulate engine coolant through an engine, the cooling system including a thermostat that controls engine coolant flow through a radiator, the method comprising:

• the controller receiving an engine coolant temperature signal from an engine coolant temperature sensor;
• the controller periodically executing a first model to generate a first thermostat position estimate to generate a plurality of first thermostat position estimates the first model being a model of a healthy thermostat;
• the controller periodically executing a second model to generate a faulty case thermostat position estimate, the second model being a model of a faulty thermostat;
• the controller generating an estimated healthy thermostat engine coolant temperature when periodically executing the first model;
• the controller generating an estimated faulty thermostat engine coolant temperature when periodically executing the second model;
• the controller comparing the healthy estimated engine coolant temperature and the faulty estimated engine coolant temperature to determine whether the thermostat is functioning appropriately;
• and
• the controller outputting a warning signal when the thermostat is not functioning appropriately.