Engine layered rapid combustion method capable of achieving multi-time natural gas spraying

Abstract

The invention aims at providing an engine layered rapid combustion method capable of achieving multi-time natural gas spraying. A system comprises an air inlet way, an exhaust way, a low-pressure natural gas injection valve and a heart-shaped pre-combustion chamber with an inclined outlet (single hole), therefore, a rolling flow, a spark plug, an in-cylinder high-pressure direct injection air injection valve and a main combustion chamber are formed in the air flow, the manner of air inlet way low-pressure injection and in-cylinder high-pressure direct injection is adopted for supplying naturalgas, for different running conditions of an engine, the different proportions of the gas total quantity needed by each cycle in the air inlet way injection and high-pressure direct injection and theair injection rule of an in-cylinder high-pressure direct injection air injection valve are adjusted, the mixed gas concentration layering from thick to thin is formed in the cylinder from a pre-combustion chamber outlet to the exterior, the distribution of the mixed gas from thick to thin is formed nearby the spark plug, and natural gas engine layering rapid combustion is achieved. Natural gas engine ignition stability is ensured, the engine efficiency is improved, and the emissions are reduced.

Description

technical field [0001] The invention relates to an engine control method, in particular to a natural gas engine combustion control method. Background technique [0002] Natural gas is abundant in my country, cheap, and clean-burning. It is a new type of energy that is very suitable as an alternative fuel for traditional internal combustion engines. Therefore, the natural gas engine is known to the public for its excellent economy. Although natural gas engines are economical to use and have clean emissions, the main component of natural gas is methane, and its ignition point is higher than that of gasoline and diesel. In the combustion process, the flame propagation speed is relatively slow, which may easily cause insufficient combustion of natural gas during the power stroke. , thus affecting the dynamic performance of natural gas engines. [0003] Most of the large natural gas engines are equipped with a pre-combustion chamber, and the high-temperature gas formed by ignit...

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Problems solved by technology

[0004] At present, the fuel supply method of most natural gas engines is to install a natural gas supply device in the intake port, and adopt a single injection of natural gas in the intake port and pre-mixing method. In this way, in order to improve the combustion performance of natural gas engines, Some patents such as CN104500248A adopt the method of injecting natural gas multiple times in the intake port. According to the different loads of the engine, the mixed gas with different concentration gradients is provided in the intake port and enters the cylinder to achieve a certain degree of stratified combustion. Single injection or multiple injection method, due to the movement of the air flow, after the mixture enters the cylinder, a single injection will make the overall mixture present a distribution of upper lean and lower thick, while multiple injections will make the overall mixture appear upper dense and lower In the lean distribution, there are a large number of local over-rich or over-lean areas. This random stratification of the mixture caused by the influence of airflow movement is a major reason for affecting the stability of natural gas flame propagation.

[0005] In order to fully combust the mixed gas, represented by MAN, a small number of natural gas engines use the method of high-pressure direct injection in the cylinder to inject natural gas into the cylinder at a time. The diffusion time in the cylinder ensures that when the ignition is fired, the mixture in the cylinder as a whole presents a distribution that is rich at the top and lean at the bottom. However, the domestic direct injection fuel technology in the cylinder is currently mostly used in dual-fuel engines or gasoline engines, such as patents CN105041512A, CN1455079A; Although the direct injection in the cylinder can effectively reduce the influence of the airflow movement, the single direct injection in the cylinder cannot realize the multi-scale stratified rapid combustion in the cylinder, and cannot timely adjust the mixture concentration gradient in accordance with the current working conditions of the engine. Incomplete combustion of natural gas still exists

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