Diagnostic apparatus of coolant temperature sensor, diagnostic apparatus of cooling apparatus and method

A diagnostic apparatus of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the apparatus comprising:

• a coolant temperature sensor sending out an output in correspondence to a temperature of the coolant;
• a setting section setting, as a measuring timing, a time when a predetermined time is elapsed after the engine started or a time when a predetermined heat is generated;
• a sampling section sampling the temperature of the coolant at the measuring timing based on the output of the coolant temperature sensor;
• a judging section judging that a trouble occurs in the thermostat when the temperature of the coolant at the measuring timing sampled by the sampling section is smaller than a first predetermined value;
• a calculating section calculating a variation amount of the output of the coolant temperature sensor from start of the engine to the measuring timing;
• and
• a prohibiting section prohibiting the judging section from judging when the variation amount is smaller than a second predetermined value.

A diagnostic apparatus of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the apparatus comprising:

• temperature detecting means sending out an output in correspondence to a temperature of the coolant;
• setting means for setting a measuring timing;
• sampling means for sampling the temperature of the coolant at the measuring timing based on the output of the temperature detecting means;
• judging means for judging that a trouble occurs in the thermostat when the temperature of the coolant at the measuring timing sampled by the sampling means is smaller than a first predetermined value;
• calculating means for calculating a variation amount of the output of the temperature detecting means from a start of the engine to the measuring timing;
• and
• prohibiting means for prohibiting the judging means from judging when the variation amount is smaller than a second predetermined value.

A diagnostic method of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the method comprising:

• sending out an output in correspondence to a temperature of the coolant;
• setting a measuring timing;
• sampling the temperature of the coolant at the measuring timing based on the output;
• judging that a trouble occurs in the thermostat when the temperature of the coolant sampled at the measuring timing is smaller than a first predetermined value;
• calculating a variation amount of the output from a start of the engine to the measuring timing;
• and
• prohibiting the judging when the variation amount is smaller than a second predetermined value.

A diagnostic apparatus of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the apparatus comprising:

• a coolant temperature sensor sending out an output in correspondence to a temperature of the coolant;
• a setting section setting a measuring section after the engine started;
• a sampling section sampling a maximum value of the output of the coolant temperature sensor in the measuring section;
• a first judging section judging whether a predetermined heat amount of the engine is generated in the measuring section;
• a second judging section judging whether the output of the coolant temperature sensor is converged in the measuring section;
• a third judging section judging that a trouble occurs in the thermostat when the first judging section judges that the predetermined heat amount of the engine is generated and the second judging section judges that the output of the coolant temperature sensor is converged in the measuring section, and when the maximum value of the output of the sensor in the measuring section sampled by the sampling section is smaller than a first predetermined value;
• a calculating section calculating a variation amount of the output of the coolant temperature sensor from a start of the engine to a start of the measuring section;
• and
• a prohibiting section prohibiting the third judging section from judging when the variation amount is smaller than a second predetermined value.

A diagnostic apparatus of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the apparatus comprising:

• temperature detecting means sending out an output in correspondence to a temperature of the coolant;
• setting means for setting a measuring section;
• sampling means for sampling a maximum value of the output of the coolant temperature sensor in the measuring section;
• first judging means for judging whether a predetermined heat amount of the engine is generated in the measuring section;
• second judging means for judging whether the output of the temperature detecting means is converged in the measuring section;
• third judging means for judging that a trouble occurs in the coolant control means when the first judging means judges that the predetermined heat amount of the engine is generated and the second judging means judges that the output of the temperature detecting means is converged in the measuring section, and when the maximum value of the output in the measuring section sampled by the sampling means is smaller than a first predetermined value;
• calculating means for calculating a variation amount of the output of the temperature detecting means from a start of the engine to a start of the measuring section;
• and
• prohibiting means for prohibiting the third judging means from judging when the variation amount is smaller than a second predetermined value.

A diagnostic method of a cooling apparatus provided with a cooling section carrying off heat of an engine by coolant to cool the engine, a radiator radiating the heat carried off by the coolant, and a thermostat controlling a flow rate of the coolant which circulates through the cooling section and the radiator, the method comprising:

• sending out an output in correspondence to a temperature of the coolant;
• setting a measuring section;
• sampling a maximum value of the output of the coolant temperature sensor in the measuring section;
• judging whether a predetermined heat amount of the engine is generated in the measuring section;
• judging whether the output of the temperature detecting means is converged in the measuring section;
• judging that a trouble occurs in the thermostat when it is judged that the predetermined heat amount of the engine is generated and that the output of the temperature detecting means is converged in the measuring section, and when the maximum value of the output in the measuring section is smaller than a first predetermined value;
• calculating a variation amount of the output in accordance with the temperature of the coolant from a start of the engine to a start of the measuring section;
• and
• prohibiting the judging that the trouble occurs in the thermostat when the variation amount is smaller than a second predetermined value.