A control method for reducing urea crystallization in engine scr tank

Abstract

The invention discloses a control method for reducing the crystallization of urea in an engine SCR box. By calculating the crystallization energy factor and controlling the opening and closing of the bypass valve based on the crystallization energy factor and the upstream temperature of the SCR by the ECU, the high-temperature exhaust gas bypass is realized according to the control method. Upon request, you can accurately know when to open the bypass valve, and then ensure that the exhaust gas from the exhaust pipe skips the turbocharger and directly enters the gas flow upstream of the SCR, so that the temperature of the exhaust gas entering the SCR box can meet the requirements of reducing the SCR box. The crystallization of urea; at the same time, it can also accurately know when to close the bypass valve, avoiding the problem of more engine pumping loss caused by the bypass valve being opened for too long, and realizing the reduction of crystallization in the SCR tank. Pumping losses are optimized for engine operation.

Description

Technical field[0001]The present invention relates to the field of engine urea crystallization technology, and more particularly to a method of controlling the crystallization of engine SCR box urea.Background technique[0002]The catalytic reduction reaction of the SCR box requires a certain temperature. When the temperature of the SCR box is low, urea cannot be followed by NO.XThe reaction is complete, and the urea that is not consumed forms a crystallization in the SCR box, affects the dynamic and emission results of the engine, and occurs when the exhaust pipe will be blocked.[0003]At present, mainly use throttle valve to control engine intake, improve exhaust temperature, and improve NOXConversion efficiency. However, the use of throttle valves to produce more pumping loss; and if the engine is running in a low load working area, urea crystallization risk will be higher. Therefore, the problem that is currently existing is that it is difficult to achieve equalization between engi...

AI Technical Summary

Problems solved by technology

However, using the throttle valve to increase the exhaust temperature will result in more pumping losses; and if the engine runs in a low-load working area for a long time, the risk of urea crystallization will be higher

Therefore, the common problem at present is that it is difficult to achieve a balance between the engine pumping loss and the reduction of urea crystallization

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