Thermostat malfunction detecting system for engine cooling system
AssigneeDenso Corporation
InventorsKeji Wakahara, Akira Ichikawa
Life of this patent
Estimating the term…
Abstract
A malfunction of a thermostat in a coolant circulating path is detected from an engine side coolant temperature in consideration of the following behavior of the coolant temperature. When an open-malfunction occurs, the coolant temperature becomes different considerably from that in the normal time in the temperature range in which the thermostat is to be normally closed. When a closure-malfunction occurs, the coolant temperature becomes different considerably from that during the normal time in the temperature range in which the thermostat is to be normally opened. Alternatively, the malfunction may be detected from a difference between the engine side coolant temperature and a radiator side coolant temperature.
Claims36
A thermostat malfunction detecting system of a cooling system of an internal combustion engine for detecting a malfunction of a thermostat provided in a coolant circulating path of an engine, comprising:
- coolant temperature detecting means for detecting a coolant temperature on the path for circulating the coolant on the engine side from said thermostat;
- and
- open-malfunction detecting means for diagnosing said thermostat whether it has a malfunction- by which it is kept opened based on the engine side coolant temperature detected by said coolant temperature detecting means in a temperature range in which said thermostat is to be normally closed.
A thermostat malfunction detecting system of a cooling system of an internal combustion engine for detecting a malfunction of a thermostat provided in a coolant circulating path of the engine, comprising:
- coolant temperature detecting means for detecting a coolant temperature on the circulating path for circulating the coolant on the engine side from said thermostat;
- and
- closure-malfunction detecting means for diagnosing said thermostat whether it has a closure-malfunction in which it is kept closed based on the engine side coolant temperature detected by said coolant temperature detecting means in a temperature range in which said thermostat is to be normally opened.
A thermostat malfunction detecting system of a cooling system of an internal combustion engine for detecting a malfunction of a thermostat provided between an engine and a radiator on a circulating path for circulating a coolant for cooling the engine, comprising:
- engine side coolant temperature detecting means for detecting a coolant temperature on the path for circulating the coolant on the engine side from said thermostat;
- radiator side coolant temperature detecting means for detecting a coolant temperature on the path for circulating the coolant on the radiator side from said thermostat;
- and
- malfunction diagnosing means for diagnosing said thermostat whether it 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.
A thermostat malfunction detecting system of an engine cooling system for detecting a malfunction of a thermostat provided in a coolant circulating path of an engine, comprising:
- coolant temperature detecting means for detecting a coolant temperature on an engine side;
- and
- malfunction diagnosing means for diagnosing a malfunction of the thermostat when the coolant temperature drops below a malfunction diagnosing temperature which is lower than a thermostat closing temperature after when the coolant temperature has reached the warm-up completion temperature.
A thermostat malfunction detecting system of an engine cooling system for detecting a malfunction of a thermostat provided in a coolant circulating path of an engine, comprising:
- coolant temperature detecting means for detecting a coolant temperature on an engine side;
- and
- malfunction diagnosing means for diagnosing the malfunction of the thermostat at least one of the occasions when the coolant temperature continuously rises even when a predetermined time has elapsed since the coolant temperature has risen above a thermostat opening temperature and when the coolant temperature continuously drops even when the predetermined time has elapsed since the coolant temperature has dropped below the thermostat closing temperature.
A thermostat malfunction detecting system of an engine cooling system which is applied to a vehicle provided with an electronic throttle for controlling an intake air amount and with an air-conditioner, comprising:
- malfunction diagnosing means for diagnosing whether said engine cooling system has a malfunction or not;
- and
- malfunction time control means for switching at least one of controls of said electronic throttle and said air-conditioner to a mode for controlling said engine cooling system when the malfunction of said thermostat is detected by said malfunction diagnosing means.
Dependencies are inferred from the claim text.