| abstract |
When an abnormality occurs in an engine or an SCR device, the release of NOx into the atmosphere is suppressed. An engine C / U 51 detects that an abnormality has occurred in the engine, and outputs a signal indicating the occurrence of the abnormality to an SCR-C / U 61. The SCR-C / U 61 increases or decreases the urea water injection amount according to the abnormality that has occurred. On the other hand, the SCR-C / U 61 detects that an abnormality has occurred in the SCR device, and outputs a signal indicating the occurrence of the abnormality to the engine C / U 51. The engine C / U 51 controls engine parts such as an EGR valve to reduce NOx emission. When an abnormality occurs in the SCR device, the urea water injection is stopped. [Selection] Figure 2 |