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
A thermostat malfunction detecting system is provided for detecting a malfunction of a thermostat in a coolant circulating path based on an engine side coolant temperature. When an open-malfunction of the thermostat 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 that which the thermostat is expected to be opened. As an alternative, the malfunction may be detected from the difference from 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;
- 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;
- and
- closure-malfunction diagnosing means for diagnosing whether said thermostat has a closure-malfunction in which said thermostat is kept closed based on the engine side coolant temperature detected by said coolant temperature detecting means in the temperature range in which said thermostat is to normally open.
A thermostat malfunction detecting system for detecting malfunction of a thermostat in a coolant circulating path of an internal combustion engine, said system comprising:
- coolant temperature detecting means disposed in the circulating path on the engine side from said thermostat;
- and
- closure-malfunction detecting means for diagnosing whether said thermostat has a closure-malfunction in which the thermostat is kept closed in a temperature range in which said thermostat is to be normally opened based on a coolant temperature detecting means output, wherein:
- said closure-malfunction detecting means corrects data used for a diagnostic process of closure-malfunction based on at least one of:
- (a) a vehicle speed, (b) an outside air temperature, (c) an intake air temperature, or (d) an operating state of an air-conditioner.
A thermostat malfunction detecting system for detecting malfunction of a thermostat in a coolant circulating path of an internal combustion engine, said system comprising:
- coolant temperature detecting means disposed in the circulating path on the engine side from said thermostat;
- and
- closure-malfunction detecting means for diagnosing whether said thermostat has a closure-malfunction in which the thermostat is kept closed in a temperature range in which said thermostat is to be normally opened based on a coolant temperature detecting means output, wherein:
- a radiator fan for cooling a radiator provided on said coolant circulating path is an electrically driven fan, and
- said malfunction detecting means diagnoses closure-malfunction solely during a period in which said radiator fan is stopped.
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;
- wherein said malfunction diagnosing means has closure-malfunction detecting means for diagnosing whether said thermostat has a closure-malfunction by which said thermostat is kept closed in the temperature range in which said thermostat normally opens.
Dependencies are inferred from the claim text.