Diesel engine combustion chamber
The merits of the diesel engine combustion chamber has a decisive role in the performance, so the diesel engine design is the key.
Combustion chamber according to the characteristics of the organization and structure divided into open, semi-open, pre-combustion chamber and swirl chamber four. The first two are direct injection combustion chamber; the latter two belong to separate the combustion chamber.
Low-speed diesel engines and parts, swirl-free high-speed diesel engine with an open combustion chamber. From the bottom of the cylinder head combustion chamber and piston top surface formed with a certain shape of the overall space. Porous injector (6 to 10 holes) to make a good fuel atomization and combustion chamber evenly distributed in space. Therefore, open burning in the combustion chamber space for a typical combustion process, requiring the combustion chamber and the beam shape and distribution of oil match. It has the advantage of low fuel consumption, easy starting; drawback is fuel atomization demanding, difficult to adapt to the variable speed work.
They use a small high-speed diesel engine with semi-open vortex chamber. This chamber is divided into several types, mainly film composite combustion chamber and combustion chamber and so on.
Combustion chamber is a 1956 film by the German Moller of the invention. Located within the piston chamber, spherical. Fuel sprayed into the engine combustion chamber wall, most of the fuel spray under the strong vortex in the combustion chamber wall, forming a thin film, a small part of the distribution of fuel atomization in the engine combustion chamber space and the first fire, which ignited the subsequent evaporation from the wall of fuel. This combustion process can work soft, burning completely, the sound of light smoke, and use of light fuel; disadvantage is more difficult to start when cold.
Composite combustion chamber in 1964 by China’s Shi Shaoxi other invention, within the dark chamber in the piston bowl-shaped top, the mouth slightly contracted, with the formation of a special shape of the inlet air swirl, the use of single-hole axis spray needle oil cooler. Injector axis parallel with the basic engine combustion chamber wall, wherein the fuel combustion chamber surrounding space. In the vortex under the action of the oil particles scattered thick wall in the combustion chamber formed on the film, a small oil particles in space and air mixture. When the speed is high, high-speed vortex combustion chamber, fuel oil film on the wall increased, the combustion characteristics of a film; start at low speed and when the vortex velocity is low, increase the amount of space for mixing the fuel with combustion characteristics of space , can improve cold starting performance.
Composite film evaporation combustion chamber and the combustion space is reasonable to combine both the advantages of both, it is also known as hybrid combustion system, soft course of their work, using a variety of combustible fuel, the engine fuel injection system requirements low, and start easily. The disadvantage is the low load the exhaust unburned hydrocarbons higher levels.
Pre-ignition chamber and the main engine combustion chamber by the pre-combustion chamber composed of two parts. Pre-combustion chamber in the cylinder head, the total volume compression of 25 to 40%, with one or more through holes connected with the main combustion chamber. Fuel injected into precombustion chamber, after the fire part of the fuel combustion, the unburned mixture of high-speed jet entered the combustion chamber, further mixed with the combustion air. This applies to small and medium power diesel engine combustion chamber.
Vortex swirl chamber and the combustion chamber from the main engine combustion chamber components. Swirl chamber located in the cylinder head, inverted bell-shaped or spherical, the total volume compression of 50 to 80%, have cut the main engine combustion chamber connected to the channel. In the compression stroke, the pressure of air into the swirl chamber produced a strong vortex motion, prompting one of the fuel injected into the air mixing. After the mixture flows entered the combustion chamber fire, the formation of secondary flow, and further with the main combustion chamber air mixture combustion.
And pre-swirl chamber combustion chamber combustion chamber combustion chamber injector needle axis are used, a lower injection pressure, reliable; As speed increases with the swirl and eddy current indoor enhanced high-speed diesel engine and the air still good Hybrid.
Swirl chamber diesel engine speed up to 4000 rev / min or more, the work process soft, exhaust less harmful components. However, heat loss and the loss of a large gas flow, and more serious after the burning, so a higher rate of fuel consumption; cold start problems, often require the installation of glow plugs.