High-pressure natural gas in-cylinder direct injection engine fuel gas injection time characteristic online identification method based on STFT

Abstract

The invention provides an on-line identification method for fuel gas injection time characteristics of a direct injection engine in a high-pressure natural gas cylinder based on STFT. A clamping type pressure sensor is installed at a high-pressure fuel gas inlet of an injector to collect pressure signals of fuel gas in the injection process of the injector; differential processing is carried out on the pressure signals, then short-time Fourier transform is carried out, then weighting processing is carried out, transient average frequency MIF is obtained, and dimension reduction processing of the pressure signals is achieved; based on the transient average frequency MIF, identification of time characteristics of the injection process is achieved through a zero point identification method; according to the invention, on-line identification of key time characteristics in the high-pressure natural gas injection process is realized, the technical bottleneck that real-time testing cannot be carried out in the actual working process of an engine in the prior art is broken through, and direct and effective injection process feedback information can be provided for an electronic control unit (ECU) of the engine; and a technical basis is provided for an advanced closed-loop control strategy in the air injection process.

Description

technical field [0001] The invention belongs to the technical field of power energy, and in particular relates to an on-line identification method for gas injection time characteristics of a high-pressure natural gas in-cylinder direct injection engine based on STFT. Background technique [0002] As one of the most important fossil fuels at present, natural gas has abundant reserves and renewable advantages and is therefore considered to be the most potential alternative fuel for internal combustion engines. At the same time, due to the advantages of natural gas with high octane number and high anti-knock, it can allow the engine to have a higher compression ratio to improve thermal efficiency. Compared with traditional gasoline and diesel engines, natural gas engines can reduce carbon dioxide emissions by 20% under the same power conditions, so they have great research prospects. [0003] The efficiency of traditional premixed combustion natural gas engines is significantl...

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Problems solved by technology

[0006] In order to solve the problem that the gas injection time characteristics of the high-pressure natural gas direct injection engine cannot be identified online, the present invention proposes a high-pressure natural gas direct injection engine based on STFT The online recognition method of g

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