| 摘要 |
According to the present invention, a purifying method for nitrogen oxide of a lean combustion engine implements catalyst regeneration in a total operation area of an engine by realizing catalyst regeneration of nitrogen oxide purifying device (7) by controlling an air fuel ratio using at least one of an engine fuel injection device (10-1), a throttle valve (10-2), an EGR valve (10-3), and a turbocharger (5) in a medium/high load operating condition; and by realizing catalyst purification of nitrogen oxide through a chemical reaction between hydrocarbon and nitrogen oxide generated when injecting a fuel pulse of a second fuel injection device (20) on a low load operating condition. More specifically, when catalyst regeneration of the nitrogen oxide purifying device (7) in a low load operating condition, a torque variation is small like the medium/high load operating condition; thereby satisfying reinforced regulation of exhaust gas due to purifying nitrogen oxide when necessary in an operating condition same during a commute or in an urban driving. |
