Abstract: A recovery control system that allows a dosing valve to recover from a malfunction to a normal state, or a liquid feed line through which urea solution is fed to recover from clogging to a normal state. An abnormality detector detects an abnormality of the dosing valve and a recovery controller controls a supply module to feed urea solution in the dosing valve back to an urea tank when the abnormality detector detects the abnormality.

Abstract: A selective catalytic reduction system (SCR) that reduces a burden on a battery resulting from energization of a heater and a decrease in time during which an NOx concentration cannot be detected. The SCR system includes: an SCR device; a dosing valve; NOx sensors; an urea solution injection control unit; electric heaters for raising respective temperatures of the NOx sensors to a sensor operating temperature; and an energization permission unit that prohibits energization of the heaters at the time of a start of an engine and permits energization of the heaters when engine revolutions become equal to or exceed a preset energization permission threshold value and such state lasts for a period of time equal to or exceeding a preset stabilization wait time.

Abstract: A selective catalytic reduction thawing control system that can distinguish between a thawing failure and a malfunction and can prevent a malfunction of a supply module (“SM”) pump. The thawing control system includes a thawing control unit that detects a pressure inside the supply module when the SM pump is operated, and stops the operation of the SM pump and continues thawing of urea water when the pressure is less than a predetermined value.

Abstract: A selective catalytic reduction system that can defrost urea aqueous solution without interruption of warm air of an engine or heating of a vehicle cabin. The system includes a defrosting control unit to open a tank heater valve at the time of starting the engine and close the tank heater valve when the temperature of the urea aqueous solution detected by a temperature sensor reaches a predetermined defrosting completion determination value, and a warm air priority control unit to prohibit the opening of the valve by the defrosting control unit when the temperature of the cooling water is less than a predetermined defrosting permission value and permit the opening of the valve by the defrosting control unit when the temperature of the cooling water is equal to or more than the defrosting permission value.

Abstract: A urea spray selective catalytic reduction (“SCR”) control system includes an SCR catalyst provided in a discharge pipe of an engine, a dosing valve for injecting urea water at an upstream side of the SCR catalyst, and NOx sensors, wherein the system controls injection of the urea water from the dosing valve. The system includes a plurality of NOx model maps corresponding to an atmospheric pressure condition, an outdoor air temperature, and an engine water temperature, and determines an amount of NOx from each NOx model map on a basis of detection values of an atmospheric pressure detector, an outdoor air temperature detector, and an engine water temperature detector, and controls an amount of injection of the urea water from the dosing valve on a basis of the amount of NOx thus determined.

Abstract: A recovery control system that allows a dosing valve to recover from a malfunction to a normal state, or a liquid feed line through which urea solution is fed to recover from clogging to a normal state. An abnormality detector detects an abnormality of the dosing valve and a recovery controller controls a supply module to feed urea solution in the dosing valve back to an urea tank when the abnormality detector detects the abnormality.

Abstract: A selective catalytic reduction (SCR) system that can prevent fixation of urea solution to an interior of a dosing valve when the urea solution is not injected through the dosing valve. An SCR system closes a dosing valve when the exhaust gas temperature is lower than a temperature at which an SCR catalyst becomes active and is provided with a fixation prevention system that opens the dosing valve and controls a supply module to feed the urea solution in the dosing valve back to a urea tank to prevent fixation of the urea solution to the interior of the dosing valve, when the exhaust gas temperature is equal to or higher than a temperature at which the urea solution crystallizes and lower than the temperature at which the SCR catalyst becomes active.

Abstract: A selective catalytic reduction system (SCR) that reduces a burden on a battery resulting from energization of a heater and a decrease in time during which an NOx concentration cannot be detected. The SCR system includes: an SCR device; a dosing valve; NOx sensors; an urea solution injection control unit; electric heaters for raising respective temperatures of the NOx sensors to a sensor operating temperature; and an energization permission unit that prohibits energization of the heaters at the time of a start of an engine and permits energization of the heaters when engine revolutions become equal to or exceed a preset energization permission threshold value and such state lasts for a period of time equal to or exceeding a preset stabilization wait time.

Abstract: A selective catalytic reduction system that can defrost urea aqueous solution without interruption of warm air of an engine or heating of a vehicle cabin. The system includes a defrosting control unit to open a tank heater valve at the time of starting the engine and close the tank heater valve when the temperature of the urea aqueous solution detected by a temperature sensor reaches a predetermined defrosting completion determination value, and a warm air priority control unit to prohibit the opening of the valve by the defrosting control unit when the temperature of the cooling water is less than a predetermined defrosting permission value and permit the opening of the valve by the defrosting control unit when the temperature of the cooling water is equal to or more than the defrosting permission value.

Abstract: A selective catalytic reduction thawing control system that can distinguish between a thawing failure and a malfunction and can prevent a malfunction of a supply module (“SM”) pump. The thawing control system includes a thawing control unit that detects a pressure inside the supply module when the SM pump is operated, and stops the operation of the SM pump and continues thawing of urea water when the pressure is less than a predetermined value.

Abstract: Provided is an exhaust gas purification system that can prevent adhesion of urea water in a dosing valve during DPF regeneration. An exhaust gas purification system 100 includes a DCU 126 that controls a supply module 106 to inject or return urea water inside a dosing valve 104 to a urea tank 105 in order to remove urea water accumulated in the dosing valve 104 when receiving a DPF regeneration authorization request from an ECM 125, and then transmits a DPF regeneration authorization to the ECM 125 when determining that an NH3 amount of an SCR catalyst is less than or equal to a prescribed value.

Abstract: A selective catalytic reduction system includes a urea aqueous solution tank to retain a urea aqueous solution to be injected into an exhaust pipe of an engine, a level sensor to detect a solution level height in the tank, a lowpass filter having a signal response characteristic in which a time constant is small when an engine rpm is low and the time constant is larger when the engine rpm is high, with respect to an output signal of the sensor, a remaining amount indicator to indicate a remaining amount of the solution based on an output signal of the sensor processed by the lowpass filter, and a unit to prohibit the engine from being started when the remaining amount of the solution is less than a lower limit value.