Thermostat malfunction detecting system for engine cooling system
AssigneeDenso Corporation
InventorsTatsuya Oka, Keiji Wakahara, Akira Ichikawa
Life of this patent
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Abstract
Malfunction of an engine coolant thermostat is detected from the engine side coolant temperature by the subsequent behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes considerably different from that normally expected for times at which the thermostat is expected to be closed. When a closure-malfunction occurs, the coolant temperature becomes considerably different from that normally expected for times at which the thermostat is expected to be opened. Alternatively, the malfunction may be detected from the difference between the engine side coolant temperature and the radiator side coolant temperature.
Claims16
A thermostat malfunction detecting system for an internal combustion engine thermostat provided in a coolant circulating path, said system comprising:
- coolant temperature detecting means in addition to said thermostat for detecting coolant temperature on the coolant circulating path on the engine side from said thermostat;
- temperature determining means which responds to said temperature detecting means for determining whether the coolant temperature detected upon starting said engine is lower than an opening temperature of said thermostat;
- and
- open-malfunction diagnosing means for diagnosing, when the coolant temperature detected upon starting said engine is lower than the opening temperature, whether said thermostat has an open-malfunction based on the engine side coolant temperature detected by said coolant temperature detecting means in a temperature range in which said thermostat is normally to be closed.
A thermostat malfunction detecting system for an internal combustion engine thermostat provided between an engine and a radiator on a coolant circulating path for cooling the engine, said system comprising:
- engine side coolant temperature detecting means for detecting a coolant temperature on the coolant circulating path on the engine side from said thermostat;
- radiator side coolant temperature detecting means for detecting a coolant temperature on the coolant circulating path on the radiator side from said thermostat;
- and
- malfunction diagnosing means for diagnosing whether said thermostat has a malfunction based on the engine side coolant temperature and the radiator side coolant temperature detected by said engine side and radiator side coolant temperature detecting means.
Dependencies are inferred from the claim text.