Engine exhaust gas temperature control system

A method of controlling an engine exhaust gas temperature comprising:

• providing a combustion chamber fluidly coupled to an intake passage and an exhaust passage with an intake valve being disposed between the intake passage and the combustion chamber and an exhaust valve being disposed between the exhaust passage and the combustion chamber;
• supplying secondary air to the exhaust passage;
• setting an valve overlapping period during which the intake valve and the exhaust valve are both open;
• and
• supplying fuel into the intake passage so that a portion of the fuel that blows by the combustion chamber and into the exhaust passage during the valve overlapping period is combusted by the secondary air in the exhaust passage.

An engine exhaust gas temperature control system comprising:

• means for providing a combustion chamber fluidly coupled to an intake passage and an exhaust passage with an intake valve being disposed between the intake passage and the combustion chamber and an exhaust valve being disposed between the exhaust passage and the combustion chamber;
• secondary air supplying means for supplying secondary air to the exhaust passage;
• valve overlapping period setting means for setting an valve overlapping period during which the intake valve and the exhaust valve are both open;
• and
• fuel supplying means for supplying fuel into the intake passage so that a portion of the fuel that blows by the combustion chamber and into the exhaust passage during the valve overlapping period is combusted by the secondary air in the exhaust passage.