US 6,321,696 B1Granted

Thermostat trouble diagnosis system in an engine cooling system

AssigneeMazda Motor Corporation

InventorsFutoshi Nishioka, Tetsushi Hosokai, Seiji Makimoto

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Abstract

The invention relates to an apparatus for diagnosing thermostat trouble in an engine cooling system comprising a thermostat which works to open a valve to make a cooling water flow through a radiator when the cooling water temperature for an engine becomes more than a predetermined temperature, or to close the valve to make the cooling water bypass a radiator when this temperature becomes less than the predetermined temperature. The apparatus comprises means for calculating a radiation heat amount from a radiator received by the cooling water for the engine and means for determining whether the thermostat trouble has occurred based on the radiation heat amount calculated by the means for calculating the radiation heat amount.

Claims12

Dependent claims

An apparatus for diagnosing a thermostat trouble in an engine cooling system comprising a thermostat which opens a valve to make a cooling water flow through a radiator when the cooling water temperature for an engine becomes more than a predetermined temperature, and closes the valve to make the cooling water bypass the radiator when the temperature becomes less than the predetermined temperature, the apparatus comprising:

calculating means for calculating a radiation heat amount from a radiator based on a predicted cooling water temperature calculated by using operating parameters indicating a condition of the engine operation and an actual cooling water temperature detected by a detecting means for detecting a temperature, and based on an integrating value of deviation between the predicted temperature and the actual temperature and a deviation between a present predicted temperature and the actual temperature;
and
determining means for determining whether the thermostat trouble has occurred, based on a result of the comparison between the actual or predicted temperature and a predetermined temperature, and the radiation heat amount calculated by the calculating means.

An apparatus for diagnosing a thermostat trouble in an engine cooling system comprising a thermostat which opens a valve to make a cooling water flow through a radiator when the cooling water temperature for an engine becomes more than a predetermined temperature, and closes the valve to make the cooling water bypass a radiator when the temperature becomes less than the predetermined temperature, the apparatus comprising a controller configured to:

calculate a radiation heat amount from a radiator received based on a predicted cooling water temperature calculated by using operating parameters indicating a condition of the engine operation and an actual cooling water temperature detected by means for detecting a temperature, and also based on an integrating value of deviation between the predicted temperatures and the actual temperature, and a deviation between a present predicted temperature and the actual temperature;
and
determine whether the thermostat trouble has occurred based on the result of a comparison between the actual or predicted temperature and a predetermined temperature the calculated radiation heat amount.

Dependencies are inferred from the claim text.