Exhaust gas purifier of construction machine

Abstract

[PROBLEM] To provide an exhaust gas purification system suitable for a construction machine provided with a hydraulic pump driven by an engine. [SOLUTION] An exhaust gas purification system is arranged on a hydraulic excavator; and includes an exhaust gas control means for performing treatment to purify nitrogen oxides in exhaust gas emitted from an engine, a urea aqueous solution reservoir for storing urea aqueous solution to be fed to the exhaust gas control means, a remaining amount detection means for detecting a remaining amount of the urea aqueous solution stored in the urea aqueous solution reservoir, a warning lamp capable of turning on when the remaining amount of the urea aqueous solution has decreased to a predetermined amount A, and a pump absorption torque limiting means or engine revolution speed limiting means disposed in a controller to perform a control of an element relating to the operation of the hydraulic actuator, for example, a control to decrease a pump absorption torque or a maximum revolution speed to a predetermined value in a range that an operation of a hydraulic actuator included in a hydraulic drive circuit becomes feasible, as the remaining amount of the urea aqueous solution becomes smaller from the first predetermined amount A.