System and method for controlling air-fuel ratio of electronic control servo pressure regulating type natural gas engine

Abstract

The invention discloses a system and method for controlling the air-fuel ratio of an electronic control servo pressure regulating type natural gas engine. The system comprises a fuel gas supply device, a compressed natural gas cylinder is connected with a natural gas pressure reduction and stabilization device through a natural gas pipeline, the natural gas pressure reduction and stabilization device is connected with an electronic control servo pressure regulating device through a natural gas filter, the electronic control servo pressure regulating device is connected with one end of a mixer through an air-fuel ratio control device, the other end of the mixer is sequentially connected with an electronic throttle valve, an intake manifold and the natural gas engine, the third end of the mixer is connected with an intercooler and a pressurizer through an air pipeline, and an electronic control system controls the opening degree of a fuel gas control butterfly valve. The flow of natural gas is controlled, the air-fuel ratio of air and the natural gas is precisely controlled, the electronic control system regulates the pressure of the natural gas by utilizing the electronic control servo pressure regulating device according to the pressure of the intake manifold of the natural gas engine, the pressure difference of the pressure in front of the fuel gas control butterfly valve and the pressure of the intake manifold is kept within the set range, and responsiveness and precision of control over the air-fuel ratio are improved.

Description

technical field [0001] The invention relates to the technical field of natural gas engines, in particular to an electronically controlled follow-up pressure-regulating natural gas engine air-fuel ratio control system and a method for the control system that improve the control accuracy of the air-fuel ratio. Background technique [0002] Natural gas is a clean fuel, almost no carbon smoke is generated in the combustion process, and the engine uses natural gas with low emissions. At the same time, it has the advantages of wide sources and low price. It is an ideal alternative energy source for internal combustion engines. [0003] At present, almost all marine engines in my country are diesel engines, which cause pollution to the water system during operation. The promotion of marine natural gas engines has become an important measure to control the pollution of inland rivers and various water systems. The air source of the marine engine is a pressurized air source, so the si...

AI Technical Summary

Problems solved by technology

[0004] At present, the supercharged single-point mixed natural gas engines for vehicles mostly use electronically controlled injection valves to control the injection volume of natural gas to control the air-fuel ratio. However, the injection valves have wear problems and have a short service life. They need to be replaced frequently during use, resulting in cost. Elevation, and the flow rate of the electronically controlled injection valve is generally small, which is not suitable for marine natural gas engines with large cylinder diameters

However, ordinary diaphragm mixers have low control accuracy for natural gas, and are not suitable for engines with supercharged natural gas / air mixture.

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