Direction-injection diesel engine combustion chamber

Abstract

The invention discloses a direction-injection diesel engine combustion chamber, belonging to the technical field of internal combustion engine structures and combustion devices. The invention is characterized in that guide convex arcs and small steps are arranged on the wall surface of the combustion chamber. The guide convex arcs and the small steps are arranged fully circumferentially, intermittently or locally. The positions of the guide convex arcs and the small steps on the wall surface are related to the shape of the combustion chamber, the size of injection holes, the angle of the injection holes, oil injection pressure, intake swirl ratio and other parameters. The cross section of each guide convex arc is semicircular, elliptic and the like. The technology adopts the guide bundle spray and stratification theory, adopts 'double wall surface injection' method to inhibit the generation of high-concentration NO at the tips of flames and promotes the mixing of the spray tips. The invention has the advantages that the even mixed gas can be formed at the premixing combustion step, the rapid mixing of oil and gas is realized, the travel time of carbon granules is shortened and thereby the oxidization time of the carbon granules is increased.

Description

technical field [0001] The invention belongs to the technical field of internal combustion engine structure and combustion device, and relates to a combustion chamber of a direct injection diesel engine. Background technique [0002] Existing direct-injection diesel engines are characterized by non-uniform and unstable spray combustion. The surrounding area of ​​the fuel spray with sufficient air supply reaches high temperature, and a large amount of NOx is generated due to the remaining oxygen. On the other hand, in fuel with insufficient air Excess areas generate PM. In the case of traditional diesel engine combustion with turbulent diffusion combustion as the main body, there are mixed gas blocks with various concentrations from the area where only air exists to the area where only fuel exists, and the mixed gas exists at the same time at the NOx and carbon particle generation speed. faster area. This is why it is difficult to simultaneously reduce NOx and PM. Homogene...

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Problems solved by technology

Early injection is divided into port injection and early injection in the compression stroke after the valve is closed. It is simple, cheap and can generate a good enough mixture. However, it is difficult to use port injection for diesel because of its high boiling point. , leading to poor evaporation; early injection in the cylinder also has problems such as high HC and CO emissions and fuel spray attached to the wall of the cylinder liner to dilute the engine oil.

Late injection is injected after the top dead center. The high swirl ratio increases the mixing rate of oil and gas. However, with the increase of engine load and the increase of fuel injection volume, it is impossible to ensure that all fuel is injected into the combustion chamber before ignition.

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