Optimization Of Start Control Strategy For High-pressure Common Rail Diesel Engine

The diesel engine has the good fuel oil efficiency and the reliability, as well as high power and durability. Compares in the gasoline engine, because the diesel engine is the compression ignition type, its may use the high compression ratio and the excess air coefficient causes the air intake valve restriction loss to reduce to is smallest, thus has the good hot merit transfer efficiency. Along with the electric control, high-pressured altogether axle, EGR and the turbo-charged technology consummates unceasingly makes diesel engine's performance to enhance unceasingly, the diesel engine applies vehicle proportion to enhance year by year.This article experiments with the engine machine GW2.8TC high pressure common rail diesel engine, uses the Bosch second generation of high pressure common rail injection system. The high pressure common rail fuel injection system has two aspect merits: first, it can come true the high pressure injection which improves the mixture formation and the combustion process. The generation of high pressure is independent of the injection process. So there is no influence of engine speed, the load and the fuel injection quantity on it in a certain range. Second, strengthens to the flexible controlling of the injection system parameters, specially the injection quantity, injection timing, injection rate, injection pressure and so on, in order to get the ideal regularity of fuel injection.The diesel engine starting operating mode is diesel engine's common operating mode. Specially, in start-up procedure, because the engine organism temperature is somewhat low, the refrigerant and the lubrication oil temperature is low, the lubricating oil viscosity is also big, does not have the sufficient lubrication, causes the piston and the cylinder wall friction drag increases, the above factor causes in the air cylinder the compression temperature, the pressure to be low, causes to gush in air cylinder's fuel oil not to be able very good to volatilize, thus the fuel oil vaporizes not well, the carburetion is non-uniform, easy to cause when the starting in the cylinder the mixture air combustion worsens, then causes the waste gas withdrawal to increase. The high-pressured common rail diesel engine also has the above question in the booster stage, domestic and foreign has conducted the massive research regarding this, improves the diesel engine starting ability in order.Before carries on the starting test to the engine, discovers when its starting the engine revolution is unstable, and discharges badly. In view of this phenomenon, through the analytical investigation hardware and in ambient condition's situation, thought that carries on the optimization to the kick fuel injection controlled variable, may improve engine's starting ability. In the other parameter invariable situation, to starts the oil mass, the host to spurt the angle of advance, altogether the axle pressure, the pre-distributive value and the pre-spraying time makes the corresponding adjustment in the starting operating mode. In order to reduce the test cycle and the work load, establishes the kick model in FIRE, and the emissions model which involves to the analog computation in has made the detailed introduction. According to the orthogonal test design, will spray the parameter to take the factor, its selection's discrete value is a level, formulates 5 factor 4 horizontal orthogonal test table, uses 16 experiments to replace 1024 experiments, the analysis analog computation emissions result, take HC, PM as well as the NOx emissions most is low as the standard, analyzes three kind of fuel injection controlled variable combination. Carries on the simulation computation again to these three kind of plans, the extraction data, the analysis exothermic rule, the temperature and the cylinder pressure, believed finally, starting oil mass 10mg/cyc, the host spurt the angle of advance 6°CA, injection pressure 40 Mpa, pre-distributive value 2 mg/cyc, pre-spraying time 13°CA this plan to cause the start-up procedure emissions to be low, and improved engine's power and the efficiency.In control software HT-LINK, affected MAP to fuel injection controlled variable MAP as well as the refrigerant temperature revision and the supply voltage to carry on the optimization. Carries on the starting test in the test bed, the test result indicated that after control policy optimization, the kick time reduces, the starting transits to the idling regime rotational speed is steady, HC, PM as well as the NOx emissions has reduces, the starting ability was improved.