| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device, restraining lowering of pressure of a reducing agent stored in a reducing agent storing part without any increase in capacity of the reducing agent storing part so that an addition amount of the reducing agent to exhaust emission is controlled with high accuracy. <P>SOLUTION: A control part 20 reduces the valve opening time of a reducing agent addition valve 15 and also opens and closes the reducing agent addition valve 15 during a shorter period of time when the pressure in an ammonia tank 17 drops lower than the pressure of exhaust emission. Thus, ammonia added from the reducing agent addition valve 15 is repeatedly supplied and stopped during a shorter period of time. Therefore, the addition of ammonia from the reducing agent addition valve 15 is stopped at early stage, so that lowering of pressure in the ammonia tank is restrained. Meanwhile, the pressure of ammonia in the ammonia tank 17 is quickly recovered by stopping to add ammonia, so that even if the capacity of the ammonia tank 17 is not enlarged, the pressure fluctuation of the ammonia is decreased. <P>COPYRIGHT: (C)2011,JPO&INPIT |
