A closed-loop control method for environmental compensation of natural gas engine

Abstract

The invention discloses a closed-loop control method for environmental compensation of a natural gas engine. By comparing the environmental parameters of the engine air inlet with the preset calibration environmental parameters, it is concluded that when the engine is in a non-calibrated environment, the electronic control unit according to the in-cylinder environment The temperature obtains the feedforward correction coefficient of the supercharged intake air amount and the air-fuel ratio, and the mixed intake air amount also obtains the feedback correction coefficient through the in-cylinder temperature, and finally obtains a considerable power output, so that the engine can work normally in any environment. Ultimately, the engine of the present invention can quickly and accurately control and correct the amount of mixed intake air entering the cylinder under any circumstances, so as to achieve the purpose of equivalent power output.

Description

technical field [0001] The invention relates to the technical field of natural gas engines, in particular to a closed-loop control method for environmental compensation of natural gas engines. Background technique [0002] Due to the shortage of oil resources in the world year by year and the increasingly serious pollution of urban automobile emissions, natural gas engines have achieved unprecedented rapid development as a green power for burning new fuels and clean energy. [0003] At this stage, natural gas engines all use electronic control technology to separately regulate the amount of fresh air and natural gas injection, and form a mixture through a mixing device, which is distributed to the cylinder through the intake manifold to burn and do work. Among them, the fresh air is supercharged by the supercharger, and after the temperature of the intake manifold and atmospheric humidity are corrected, the supercharged intake air volume is obtained; the natural gas is injec...

AI Technical Summary

Problems solved by technology

[0004] However, the current control system can only control and correct the mixed intake air volume in a laboratory environment or a calibrated controllable environment to achieve the engine calibration performance. As the engine working environment becomes worse (relative to the controllable calibration environment), The ambient temperature is high or low, the altitude is high or low, the ambient humidity is high or low, etc., the adjustment and correction of the existing control system can no longer meet the requirements of the normal operation of the engine, for example, in the case of high ambient temperature , the amount of mixed intake air entering the cylinder will be reduced due to the reduction of air density, which will eventually lead to a reduction in engine output power

Further problems and deficiencies include: under normal circumstances, the length of exhaust gas transmission in the engine exhaust pipe under different operating conditions is different, which will cause changes in the feedback signal of the oxygen sensor. When the throttle opening changes greatly , the air-fuel ratio will fluctuate instantaneously due to the large deviation between the feed-forward value and the actual intake air volume, which makes it difficult for the control system to accurately adjust the mixed intake air volume. In severe cases, it will lead to unstable engine speed or power output, or even flameout

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