Three-valve injection method of urea reducing agent

Abstract

The invention relates to a three-valve injection method of a urea reducing agent. The method is characterized by comprising the following steps of: pressing liquid in a urea reducing agent box to pass by a filter through a pipeline under the drive of pressure, wherein the pipeline is connected in series with the filter; respectively connecting the pipeline passing by the filter with three electromagnetic flow control valves in parallel so that the liquid singly passes by the electromagnetic flow control valves or is simultaneously converged to a stabilization valve; then, conveying the liquid from the stabilization valve to a urea reducing agent nozzle; and injecting the liquid in a vent pipe under the aid of air. The invention can cancel a DOC (Diesel Oxidation Converter) device for the oxidation treatment of NH3, simplifies the vehicle device and decreases the cost.

Description

Technical field: [0001] The invention relates to a three-valve injection method of a urea reducing agent, which is applied to the post-treatment industry of automobile exhaust. Background technique: [0002] In the next few years, global automobile manufacturers, especially the United States and Europe, will enforce some stricter standards on vehicle nitrogen oxides NOx and particulate PM emissions, such as Euro 5 and Euro 6 emission standards. [0003] Under the pressure of emission regulations, on the one hand, foreign heavy-duty diesel engines for vehicles are constantly upgrading and improving their technology; , DPF (Diesel Particulate Filter) particle trap, DOC (Diesel Oxidation Catalyst) oxidation catalyst, etc. [0004] The essence of SCR technology is to use urea to decompose NH at high temperature 3 , NH as reducing agent 3 and NO in engine exhaust x The reaction is carried out under the combined action of catalyst and temperature, and under ideal conditions,...

AI Technical Summary

Problems solved by technology

If you choose a domestically produced electromagnetic flow control valve with low precision to achieve control, the theoretically set flow rate is 5~85g / min. When a working condition requires a supply of 60g / min reducing agent, according to its error, its The actual flow range may reach 42~78g / min. For the flow rate of 42g / min, the possible result is that the supply of urea reducing agent is insufficient to remove the specified amount of NOx; while for the flow rate of 78g / min The possible result is that the supply of urea reducing agent exceeds the standard. Although the specified amount of NOX can be removed, it will definitely cause excessive escape of NH3. create new pollution

[0015] Patent No. CN200510129691.6 for 'system for controlling urea supply to SCR catalyst' patent, patent No. CN200510136379.X for 'a control reducing agent A method of injecting NOx-containing exhaust gas from an internal combustion engine' patent, patent number CN200810095099.2 'A device for distributing fluidity additives in an internal combustion engine exhaust system' patent, patent number CN200920045181.4' The patent of the injection ammonia injection mixing mechanism of an SCR reaction device', the patent number is CN200810047114.6'The control method and control device for controlling the amount of adding blue used in the diesel engine SCR system'The patent, the patent number is CN98805246. 6's patent on 'A Method for Reducing NOx Emissions from a Lean Burn Engine Associated with the Exhaust System', the patent number is CN200580030812. X's patent on 'Control System for Engine Aftertreatment System', the patent number is Patents such as CN200480017220.X's "Method of Controlling Reductant Addition" are only related to the signal acquisition and strategy of urea reductant dose, the position where urea reductant is injected, the shape of the nozzle, pipelines, mixing methods, etc., and No actual control methods and means for measurement

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