Method and means for pre-heating the intake air of a supercharged, low-compression ratio diesel engine when operating at low load

In combination with a supercharged low compression ratio diesel engine including an exhaust duct, an air intake duct, an exhaust gas-driven turbine connected in said exhaust duct and having an inlet for receiving exhaust gases from said engine and an outlet for said gases, a supercharging air compressor, means operatively coupling said turbine to said compressor, said compressor having a discharge outlet connected to said air intake duct and an aftercooler located in the intake duct downstream of the supercharging air compressor and having a cooling fluid inlet adapted to be connected to a source of cooling fluid and a cooling fluid outlet, a device for preheating the intake air to said engine, said device comprising:

• heat exchange apparatus having a heating fluid input for receiving exhaust gases from the engine, a heating fluid output for the exhaust gases, a heated fluid input for receiving intake air for the engine, a heated fluid output for delivering heated intake air to the air intake duct of the engine, and a heat conveying means moving in a closed path of travel adapted to be in heat transfer relation with engine exhaust gases flowing between the heating fluid input and output for one part of the closed path and in heat transfer relation with engine intake air flowing between the heated fluid input and output for another part of the closed path;
• a controllable three-way valve located in said exhaust duct and having an outlet connected to said heating fluid input of said heat exchange apparatus;
• and
• means for operating said three-way valve to selectively control the flow of exhaust gases to the heating fluid input of said heat exchange apparatus for heating said heat conveying means in the one part of said closed path.