Control method and device of engine

Abstract

The invention discloses a control method and device of an engine. The control method of the engine comprises the following steps that 1, if the actual value of the nitrogen oxide emission parameter of the engine is greater than a first limiting value, a function relation expression of the nitrogen oxide emission parameter of the engine about at least one operation parameter of the engine is obtained, and the at least one operation parameter comprises the main injection advance angle of an injector of the engine; 2, a first-order derivative of the function relation with respect to a main injection advance angle of the injector of the engine is solved; 3, the set value of the at least one operation parameter is substituted into the first-order derivative to obtain a derivative value; and 4, the set value of the main injection advance angle of the injector of the engine is corrected on the basis of the derivative value. According to the technical scheme, the main injection advance angle can be corrected in real time under the condition that original emission nitric oxide exceeds the limit value, so that the original emission nitric oxide is controlled within a certain range, the tail gas aftertreatment control difficulty is reduced, the stability is improved, and emission is prevented from exceeding the standard.

Description

technical field [0001] The present invention relates to the technical field of engines, and in particular, to a control method and device for an engine. Background technique [0002] With the continuous development of automotive electronic technology, diesel engine emission control has been paid attention to by the national environmental protection department. Selective catalyst reduction (SCR) is a treatment process for NOx in diesel vehicle exhaust emissions. Catalytic reduction, so as to achieve both energy saving and emission reduction purposes. [0003] The NOx control method of engine exhaust emission is to calculate the urea injection amount based on the original exhaust level of the engine and the calibrated ammonia nitrogen ratio. When the external factors change and cause the original exhaust NOx of the engine to be too large, the urea injection amount will also increase accordingly. Due to the limitation of the conversion efficiency, the urea cannot be completel...

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Problems solved by technology

[0003] The NOx control method of engine exhaust emission is based on the original exhaust level of the engine and the calibrated ammonia-nitrogen ratio to calculate the urea injection amount. Due to the limitation of conversion efficiency, urea cannot be completely reacted, resulting in excessive ammonia leakage, and tail NOx cannot be controlled within the original level range

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