| 摘要 |
PROBLEM TO BE SOLVED: To provide a reducing agent supply device capable of continuing NOpurification control by estimating supply pressure even in a failure of a pressure sensor.SOLUTION: A reducing agent supply device mounted on an exhaust purification device to purify nitrogen oxide in exhaust by using liquid reducing agent comprises: a pump which pumps liquid reducing agent in a storage tank; a solenoid injection valve to inject pumped liquid reducing agent into an exhaust pipe of an internal combustion engine; and solenoid injection valve control means which controls the solenoid injection valve in accordance with a target injection amount. In addition, the reducing agent supply device has pressure estimation control means which estimates supply pressure of the liquid reducing agent on the basis of a period between a valve opening start time and a valve opening finish time of the solenoid injection valve and an electric current value supplied to the solenoid injection valve. The solenoid injection valve control means also controls the solenoid injection valve using the estimated supply pressure. |
