Oxygen sensor-based urea jet control device for diesel and control method for jet control device

Abstract

The invention discloses an oxygen sensor-based urea jet control device for a diesel and a control method for urea jet control device, and relates to a post-treatment selective catalytic reduction (SCR) control technology of the diesel. The jet control device comprises an electric control unit (ECU), a urea box, a urea pump, a urea nozzle, an SCR box, an SCR box front air exhaust pipe, an SCR box rear air exhaust pipe, an SCR box front oxygen sensor and an SCR box rear oxygen sensor, wherein the SCR box front oxygen sensor and the SCR box rear oxygen sensor are respectively arranged on the SCR box front air exhaust pipe and the SCR box rear air exhaust pipe; closed-loop control of jet volume of urea, namely NH3 is realized through signals of the SCR box front oxygen concentration sensor and the SCR box rear oxygen concentration sensor; a calibration value of NOx discharged from tail gas is corrected and compensated through the signals of the SCR box front oxygen sensor and the SCR box rear oxygen sensor; and the reaction efficiency of the SCR box is judged through the signals of the SCR box front oxygen sensor and the SCR box rear oxygen sensor, and the jet volume of the NH3 is accurately controlled; and the price of the oxygen sensor is far lower than that of a NOx sensor. By the urea jet control device, urea jet is controlled through the signals of the SCR box front oxygen sensor and the SCR box rear oxygen sensor, so that the cost of post-treatment systems is greatly reduced.

Description

technical field [0001] The invention discloses a diesel engine urea injection control device and method based on an oxygen sensor, and relates to the diesel engine post-processing SCR control technology. Background technique [0002] NOx and PM are the main pollutants emitted by diesel engines, and it is impossible to significantly reduce PM and NOx emissions at the same time through internal measures. In order to meet the increasingly stringent automobile exhaust emission regulations, a widely adopted method is to first reduce the particulate matter to an appropriate level through fuel injection system optimization, injection timing advance and supercharged intercooling, which will lead to an increase in NOx components in the exhaust gas. Then use selective catalytic reduction technology (SCR) to reduce NOx emissions. Aqueous urea solution is converted to NH under high temperature of tail gas 3 , and then react with NOx in the SCR box to convert NOx harmful to human body ...

AI Technical Summary

Problems solved by technology

The diesel engine ECU can calibrate the NOx concentration in the exhaust directly discharged from the diesel engine in front of the SCR tank according to the engine intake air volume and actual fuel injection volume. However, due to the aging of the engine body, fuel system, supercharger, intercooler and other components, the combustion and The problem of inconsistency in the initial state of the factory will cause the amount of NOx in the exhaust gas emitted by the diesel engine to change, so the initial NOx prediction must be corrected

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