Return control system

Abstract

Provided is a return control system for implementing return to normal status by resolving malfunctioning of a dosing valve or clogging of a liquid transfer line through which urea water flows. A return control system for returning to normal status when a dosing valve (104) malfunctionsis provided with: anomaly detection means for detecting anomalies in the dosing valve (104); and return control means for controlling a supply module (106) in order to return urea water inside the dosing valve (104) to a urea tank (105) when a dosing valve (104) anomaly has been detected by the anomaly detection means.

Description

technical field [0001] The present invention relates to a recovery control system for eliminating malfunction of a metering valve or blockage of a liquid delivery pipeline for delivering urea water and returning to a normal state. Background technique [0002] Used to purify NO in the exhaust gas of diesel engines X developed an SCR system using an SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) device. [0003] The SCR system provides the urea water stored in the urea tank to the exhaust gas upstream of the SCR, uses the heat of the exhaust gas to generate ammonia, and uses the ammonia to reduce NO on the SCR catalyst X A system that performs purification (see, for example, Patent Document 1). [0004] use here Figure 6 Describe the process of producing ammonia from urea water. [0005] like Figure 6 As shown, if the temperature of urea water becomes higher than the boiling point, its moisture will start to evaporate, and gas will be generated throug...

AI Technical Summary

Problems solved by technology

[0013] Since the quantitative valve 104 is arranged in the engine exhaust pipe where the high-temperature exhaust gas flows, if the quantitative valve 104 becomes high temperature, the urea water in the quantitative valve 104 also becomes high temperature, as Figure 8 As shown in (a), the urea water in the quantitative valve 104 is crystallized, and the valve body 129 is stuck, or like Figure 8 As shown in (b), the crystallized solid 134 of the urea water is sandwiched between the valve body 129 and the valve seat of the hydraulic cylinder 127, and the injection of the urea water cannot be stopped, resulting in malfunction of the metering valve 104, and proper injection cannot be performed. Problems such as urea water injection control

[0014] Moreover, when the liquid delivery pipeline connecting the urea tank and the supply assembly is blocked by some foreign matter, etc., there is a problem that the pressure of the urea water in the quantitative valve 104 is not constant—that is, the pressure does not rise, and the urea water does not start to be sprayed.

[0015] However, recovery control from such problems to a normal state has so far not

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