Abstract
NOx concentration is greatly influenced by combustion flame temperature and its stay time. Fuel injection timing retard avoids a remarkable rise of combustion flame temperature, and is effective in reduction of NOx concentration. Moreover there is no necessity for the special external equiment with this method, which is generally adopted with great effect for expense. However, fuel injection timing retard will bring about an increase of SFOC with a fall of the combustion maximum pressure, and it is usually reported that SFOC will increase by 3% when NOx concentration decreases by 20% with the above method.
At the first stage, we examined fuel injection timing retard with an aim at reduction of NOx concentration, and at the next stage, examined a rise of compression ratio with an aim at improvement for SFOC increase and exhaust gas temperature increase caused by fuel injection timing retail.
