| 摘要 |
PROBLEM TO BE SOLVED: To provide a urea injection device capable of preventing an obstacle by freezing of a urea aqueous solution. SOLUTION: This urea injection device 4 sprays the urea aqueous solution 5 to an SCR (selective catalytic reduction) part 3 arranged on the downstream side of an oxidation catalyst part 2 of an exhaust pipe 1. An electromagnetic pump 7 capable of switching force feed operation and suction operation is arranged between a tank 6 and a sprayer 8. The electromagnetic pump 7 is connected in series with a tank side assembly 7A and a sprayer side assembly 7B. The tank side assembly 7A and the sprayer side assembly 7B have a pipe reciprocatably supported in the axial direction by an electromagnet, a pair of moving pieces fixed to both ends of the pipe and movably arranged in a moving piece moving space formed on both sides of the electromagnet, a pair of diaphragms arranged in the pair of moving pieces, a pair of volume changing chambers formed outside in the axial direction of the pair of diaphragms and communicated by the pipe, and a pair of valve elements leaving from and seated on a valve seat by reciprocating motion of the pipe. COPYRIGHT: (C)2011,JPO&INPIT |
