Diesel oil ignition natural gas engine combustion system and control method thereof

Abstract

The invention relates to a diesel oil ignition natural gas engine combustion system and a control method thereof. The diesel oil ignition natural gas engine combustion system comprises an engine body,a diesel oil inlet system, a natural gas inlet system, a variable cross-section turbocharger VGT, an exhaust gas recirculation system EGR, a variable valve regulator VVT, a dual-fuel ECU, a comprehensive ECU, a computer and a power source, wherein the exhaust gas recirculation system EGR comprises an EGR intercooler and an EGR valve. According to the system, according to different operation conditions of an engine, accurate control over the fuel gas amount is achieved through strategies of adjusting a gas channel and gas injection of a gas injection valve in a cylinder, mixed gas with different filling amounts and layering states is formed in the cylinder, thermodynamic state control is coupled on the basis, through combined control of the variable valve regulator VVT and the exhaust gasrecirculation system EGR and cooperation of different equivalent ratios, stable ignition and controllable stratified combustion under various working conditions are achieved, the natural gas replacement ratio of a dual-fuel engine is further increased, and efficient and clean combustion within a wider working condition operation range is achieved.

Description

technical field [0001] The invention relates to a diesel ignited natural gas engine combustion system and a control method thereof, belonging to the technical field of internal combustion engine combustion. [0002] technical background [0003] In the face of environmental pollution, increasingly stringent emission regulations continue to push internal combustion engines towards zero emissions. Among many alternative fuels, natural gas has been widely used in heavy trucks, urban buses, ships and other fields due to its abundant storage and low price. The main component of natural gas is methane (CH 4 ), has the characteristics of high octane number, low chemical activity and good anti-knock performance, which is conducive to improving the mean effective pressure (BMEP) and thermal efficiency of the engine (which can increase the compression ratio); at the same time, natural gas has a high H / C ratio and low sulfur content And no aromatic hydrocarbons, which is beneficial to...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a combustion system and its control method for a diesel ignited natural gas engine, by means of natural gas direct injection and port compound injection strategy, variable valve technology, and exhaust gas recirculation strategy to realize the coupling control of stratification and thermodynamic state in the natural gas cylinder Diesel ignites the combustion of natural gas engines, which solves the problems of poor combustion stability at low loads at high substitution ratios and easy knocking at high loads at high compression ratios faced by natural gas intake port injection engines, and further increases the natural gas substitution ratio of dual-fuel engines , to achieve efficient and clean combustion in a wider operating range

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