System for controlling recirculated exhaust gas temperature in an internal combustion engine

Apparatus for controlling the temperature of recirculated exhaust gas in an internal combustion engine, comprising:

• a first conduit coupled at one end to an exhaust gas port of the engine;
• a second conduit coupled at one end to an air inlet port of the engine;
• a source of coolant fluid;
• a heat exchanger including a gas inlet port connected to an opposite end of said first conduit and receiving exhaust gas therefrom, a gas outlet port connected to an opposite end of said second conduit and supplying recirculated exhaust gas thereto, a coolant inlet port connected to said source of coolant fluid and a coolant outlet port, said heat exchanger defining a coolant flow path therethrough from said source of coolant fluid to said coolant outlet port;
• a coolant control valve disposed within said coolant flow path and operable to control a rate of coolant flow therethrough;
• a first temperature sensor disposed within said coolant flow path and operable to produce a first temperature signal corresponding to coolant fluid temperature entering said heat exchanger;
• a second temperature sensor disposed within said coolant flow path and operable to produce a second temperature signal corresponding to coolant fluid temperature exiting said heat exchanger;
• and
• an electronic control system responsive to said first and second temperature signals to provide a coolant valve control signal corresponding thereto, said coolant control valve responsive to said coolant valve control signal to control said rate of coolant flow through said coolant flow path and thereby control said recirculated exhaust gas temperature.

Apparatus for controlling the temperature of recirculated exhaust gas in an internal combustion engine, comprising:

• a first conduit coupled at one end to an exhaust gas port of the engine;
• a second conduit coupled at one end to an air inlet port of the engine;
• a heat exchanger including a gas inlet port connected to an opposite end of said first conduit and receiving exhaust gas therefrom, a gas outlet port connected to an opposite end of said second conduit and supplying recirculated exhaust gas thereto, said heat exchanger defining a number of exhaust gas flow paths therethrough from said gas inlet port to said gas outlet port;
• means for selectively disabling exhaust gas flow through certain ones of said number of exhaust gas flow paths;
• and
• means for controlling said means for selectively disabling exhaust gas flow through certain ones of said number of exhaust gas flow paths to thereby control the temperature of said recirculated exhaust gas.

Apparatus for controlling the temperature of recirculated exhaust gas in an internal combustion engine, comprising:

• a source of coolant fluid;
• a heat exchanger including a housing defining a gas inlet port, a gas outlet port, a coolant inlet port and a coolant outlet port, said gas inlet port coupled an exhaust gas port of the engine, a gas outlet port coupled to an air intake port of the engine, a coolant inlet port connected to said source of coolant fluid and a coolant outlet port, said heat exchanger defining a coolant flow path therethrough from said source of coolant fluid to said coolant outlet port;
• a coolant control valve disposed within said coolant flow path and operable to control a rate of coolant flow therethrough;
• a temperature sensor operable to sense heat exchanger housing temperature and produce a temperature signal corresponding thereto;
• and
• an electronic control system responsive to said temperature signal to provide a coolant valve control signal corresponding thereto, said coolant control valve responsive to said coolant valve control signal to control said rate of coolant flow through said coolant flow path and thereby control said recirculated exhaust gas temperature.

Apparatus for controlling the temperature of recirculated exhaust gas in an internal combustion engine, comprising:

• a source of coolant fluid;
• a heat exchanger receiving exhaust gas from an exhaust gas port of the engine and providing recirculated exhaust gas to an air intake port of the engine, said heat exchanger defining a coolant flow path therethrough and having a coolant control valve operable to control a rate of coolant fluid flow through said flow path from said source of coolant fluid;
• a first temperature sensor disposed within said coolant flow path and operable to produce a first temperature signal corresponding to coolant fluid temperature entering said heat exchanger;
• a second temperature sensor disposed within said coolant flow path and operable to produce a second temperature signal corresponding to coolant fluid temperature exiting said heat exchanger;
• and
• an electronic control system responsive to said first and second temperature signals to provide a coolant valve control signal corresponding thereto, said coolant control valve responsive to said coolant valve control signal to control said rate of coolant flow through said coolant flow path and thereby control said recirculated exhaust gas temperature.