US 10,378,422 B2Granted

Thermostat abnormality determining device

AssigneeHino Motors, Ltd.

InventorsMotoyoshi Kaneta, Hitoshi Nakano

Life of this patent

Estimating the term…

Loading patent…

Abstract

This thermostat abnormality determining device includes a cooling water temperature sensor, an estimated temperature calculating unit and a determining unit. The cooling water temperature sensor detects the temperature of cooling water that cools an engine. The estimated temperature calculating unit calculates an estimated temperature, which is an estimated value of the temperature of the cooling water. The determining unit determines if the thermostat has become stuck open after warming-up of the engine is complete. The criteria whereby the determining unit determines that the thermostat has become stuck open are that the estimated temperature is higher than a stuck-open determining temperature, which is a temperature lower than a warm-up completion temperature indicating that warming-up of the engine is complete, and that the cooling water temperature, which is the value detected by the cooling water temperature sensor, has been continuously at or below the stuck-open determining temperature for a determination period.

Claims4

Dependent claims

An abnormality determining device for a thermostat comprising:

a coolant temperature sensor that detects a temperature of coolant for cooling an engine;
an estimated temperature calculation section that calculates an estimated temperature, which is an estimated value of the temperature of the coolant;
and
a determination section that determines that the thermostat is stuck open after completion of warm-up of the engine,
wherein the determination section determines that the thermostat is stuck open on condition that
the estimated temperature has been higher than a stuck-open state determination temperature that is lower than a warm-up completion temperature, which indicates completion of warm-up of the engine,
a state in which a coolant temperature, which is a detection value of the coolant temperature sensor, has been lower than or equal to the stuck-open state determination temperature continues for a determination period, and
the estimated temperature calculation section calculates the estimated temperature while setting an upper limit value to an equilibrium temperature of the coolant when the thermostat is in an open valve state.

5 more elements

Dependencies are inferred from the claim text.