Patent ID: 8316636
Filing Date: 2012-11-27
Classification: B01D,E02F,F01N,F02D,Y02T

Abstract:
1. An exhaust gas purification system for a construction machine provided with an engine, a variable displacement hydraulic pump driven by said engine and controlled such that an absorption torque does not exceed an output torque of said engine, a regulator for controlling a swash angle of said variable displacement hydraulic pump, and a hydraulic drive circuit including plural hydraulic actuators to which pressure oil delivered from said variable displacement hydraulic pump is fed, comprising: an exhaust gas purifying device for conducting treatment to purify nitrogen oxides in exhaust gas emitted from said engine; a reducing agent solution reservoir for storing a reducing agent solution to be fed to said exhaust gas purifying device; a remaining amount detecting device for detecting a remaining amount of said reducing agent solution stored in said reducing agent solution reservoir; an alarm operatively configured to provide a warning to an effect that a replenishment of said reducing agent solution is required, when said remaining amount of said reducing agent solution as detected by said remaining amount detecting device has decreased to a first predetermined amount; and a state quantity control device for performing a control to gradually decrease a state quantity relating to a drive of said variable displacement hydraulic pump to a predetermined value in a range that an operation of said hydraulic actuator becomes feasible while as said remaining amount of said reducing agent solution as detected by said remaining amount detecting device becomes smaller from said first predetermined amount to a second predetermined amount smaller than said first predetermined amount and for maintaining said state quantity within a range of said predetermined amounts in which the operation of said hydraulic actuator becomes feasible when said remaining amount of said reducing agent solution as detected by said remaining amount detecting device becomes smaller from said second predetermined amount, wherein said swash angle of said variable displacement hydraulic pump is controlled by said regulator and said variable displacement hydraulic pump is torque-controlled such that said absorption torque does not exceed said output torque of said engine in a state where said state quantity relating to said drive of said variable displacement hydraulic pump is controlled by said state quantity control device.