Abstract: A selective catalytic reduction (SCR) system that can suppress thermal damage in operation of a dosing valve resulting from crystallization of urea solution and corrosion of the dosing valve to perform proper urea solution injection control, and includes an SCR device provided in an exhaust pipe of an engine; a dosing valve that injects urea solution at an upstream side of the SCR device; a minimum injection quantity setting unit that if temperature of the dosing valve is equal to or higher than a predetermined temperature, sets a minimum injection quantity according to the temperature of the dosing valve; and an urea solution injection control unit that if injected quantity of urea solution according to quantity of NOx emitted from the engine is smaller than the minimum injection quantity, controls the injected quantity of urea solution to be the minimum injection quantity.

Abstract: A selective catalytic reduction (SCR) system that can suppress thermal damage in operation of a dosing valve resulting from crystallization of urea solution and corrosion of the dosing valve to perform proper urea solution injection control, and includes an SCR device provided in an exhaust pipe of an engine; a dosing valve that injects urea solution at an upstream side of the SCR device; a minimum injection quantity setting unit that if temperature of the dosing valve is equal to or higher than a predetermined temperature, sets a minimum injection quantity according to the temperature of the dosing valve; and an urea solution injection control unit that if injected quantity of urea solution according to quantity of NOx emitted from the engine is smaller than the minimum injection quantity, controls the injected quantity of urea solution to be the minimum injection quantity.

Abstract: An exhaust emission control system including a continuous regenerating diesel particulate filter (“DPF”) and a DPF controller, wherein a forced regenerator is operated by a driver's request, when it is judged that a traveling distance, after starting particulate matter collection, detected by a traveling distance detector has reached a predetermined judging traveling distance, even when the DPF controller detects that a collection amount detected by a collection amount detector is smaller than a prescribed judging collection amount. Accordingly, in a continuous regenerating DPF capable of manual regenerating, the number of warnings, such as a blinking regeneration button prompting a manual regeneration, is reduced to relieve a driver of annoyance or inconvenience.

Abstract: An exhaust emission control system [1] comprising a continuous regenerating DPF [13] and a DPF controlling means [30C], wherein control is so performed as to accept the operation of a forced regenerating means [34C] at an operation request by a driver when it is judged a traveling distance [?Mc] after starting collection detected by a traveling distance detecting means [33C] has reached a specified judging traveling distance [?M1] even when the DPF controlling means [30C] detects a collection amount [?Pm] detected by a collection amount detecting means [32C] is smaller than a specified judging collection amount [?P1]. Accordingly, in a continuous regenerating DPF [13] capable of manual regenerating, the number of warning such as a blinking regeneration button prompting a manual regeneration is reduced to relieve a driver of trouble.