Development And Control Of The High-pressure Common Rail Diesel Engine Combustion On Vehicle Performance

As the increasingly serious challenge of the automobile industry from energy and environment, it requires more and more on the development of the high efficiency and low emission. Automobile researching takes reversing development forms in China all the time, it choice models according to demanding of the market, and then choosing the appropriate transmission device by comparing with similar models, finally to the engine. At present, more and more automobile factories and scientific research institutes are beginning to focus on integration control system of whole-car power transmission system, and to study energy conservation and emission control to meet the Emission regulations, but it is not designed engine from the management of whole-car power transmission system and cannot be achieved purpose of matching. Based on this, the paper combining enterprise horizontal topic of engine based on the vehicle performance of positive development technology launched related research.High speed direct injection diesel engine requires fast mixture formation. In order to suffice the rapidity formation of gas mixture of diesel engine for automobile and base on vehicle performance needs better high and low speed change characteristic, the paper proposed a specific method to study reentrant low-emission chamber. The method is use squeeze (swirl) intensity and maintenance to quantitative analyzes the airflow characteristics of the combustion chamber, and uses these as the evaluation to a design of chamber. At first use this method to simulate the shape parameter of chamber important to the performance of diesel engine and airflow characteristic, such as reentrant ratio, piston cup center height, TDC clearance height. Based on this, redesign two reentrant combustion chambers on the base of origin engine of 2.8TC, and then analyze airflow characteristics of the two reentrant combustion chambers though simulation comparison, piston machining and experiment also. Though the comparison analysis between the two different reentrant structure chambers performance test, proves the method to design and evaluate chamber in this paper is completely feasible, can guide the design of reentrant chamber.In order to make full use of the structural characteristics of reentrant combustion chamber, meet the requirements of high speed diesel engine, the development of the combustion chamber and fuel injection system structural parameter (fuel injector and injection position) are matched, basis on this to further evaluation the designed combustion chamber, use of squeeze (swirl) intensity and evaluating indicator of its retentivity, analyse the effect of intake swirl ratio (1.4,1.8,2.1) under engine speed 3000r/min and different speed (3000r/min and 3600r/min) under intake swirl ratio 1.8 on the characteristic of air field in gasoline cylinder, Finally, carry on the match research of pressure intensifier and the EGR.1) When the number of spray holes are same, injector have bigger hole diameter, rate of fuel consumption relatively lower, engine output torque more, when the injector circulation area are same, rate of fuel consumption decreases while the spray holes increases, engine output torque augment. As the normalized flow rate difference 100cm3/min, the external characteristics BSFC maximum difference up to 10%, smoke emission maximum difference up to 40% . Injector spacer have an optimal thickness, when the spacers thickness on the small side, the length of injector deep in cylinder overlength, could result in eddy before exhaust gas temperature ascend and higher rate of fuel consumption, when the spacers thickness on the big side, the length of injector deep in cylinder shorter, could result in eddy before exhaust gas temperature ascend and generates too much soot. Base on the above injector spray holes, hole diameter, injector flow characteristic and spacer thickness matching analysis, we select the injector have 6 holes, hole diameter 0.137, flow 700 cm3/mim and 2mm spacer thickness, and matching it withâ… type combustion chamber.2) Intake swirl ratio and engine speed have a important effect of in-cylinder flow characteristics. In this paper three swirl ratio 1.4,1.8,and 2.1 are choiced. When engine speed is 3000 r/min and spray parameters are constant, the bigger the intake swirl ratio, the greater the squeeze intensity, the squeeze intensity decays faster and the squeeze intensity maintenance decreases after spraying, and the smaller the intake swirl ratio, the better the squeeze intensity for squeeze intensity and squeeze intensity maintenance. The bigger the intake swirl ratio, the greater the swirl intensity and there is a little relationship between the swirl intensity maintenance and intake swirl ratio. When the intake swirl ratio is constant, the two conditions(3000r/min and3600r/min) have the same squeeze intensity and squeeze intensity maintenance. Whether the spraying is underway or over, the squeeze intensity is greater comparatively when the engine speed is 3000r/min. The squeeze intensity maintenance is greater comparatively and it can promote the diffusion combustion when the engine speed is 3600r/min. At the same time, it proves that the reentrant chamber in this paper has a good high-speed adaptability.3) VGT and VNT can satisfy the goal the enterprise advanced. Japan's Ishikawajima VNT improved the full load characteristic effectively, especially the low speed torque characteristic, and soot,temperature before turbine and BSFC are lowly.4) We optimized the EGR of all the conditions to the engines based on EGR stepper motor control system after analyzing the impact mechanism of the generation of NOx and smoke using EGR and the effect of the NOx and smoke made by the EGR rate of various conditions. The result shows:the EGR stepper motor control system we give here can effectively improve the NOx emissions by matching EGR well.The present papers from the perspective of vehicle firstly investigated the engine injection quantity control method on traction requirement, and give out the detailed traction-based injection quantity algorithm and control strategy. Establishing controlling flow of injection quantity control method based on traction requirement, and analyzed the control strategy of injection quantity,injection timing and injection pressure; According to whether or not have traction of vehicle, the condition of the engine was differentiate start,idling,full load,part load and limit speed, and gave out the control methods of primary control variable of these condition and safeguard of the injection quantity.With the demand of vehicle dynamic performance keep rising, how to optimize electrical parameter of calibration engine makes vehicle possess fine dynamic, economy and meet emissions requirements is particularly critical. Think from the perspective of vehicle driving performance, base on the theory of traction control engine fuel charge, to research the relation among rail pressure, injection timing, pre-injection time, pre-fuel charge and effect factor of MAP by its control, summing up the principle and method of every system parameter in calibration procedure, and calibrating the important picture of MAP based on traction control, through the series of control the MAP setting, and the optimized calibration of control parameters of fuel injection volume, injection timing and rail pressure etc., to the satisfy the basis of qualification of the smoke emission, the cylinder peak pressure and the exhaust temperature, the actual total load speed and the target characteristic curve characteristic curve in good agreement. With the fuel injection volume to control the MAP and the initial calibration of other control parameters, the economy and emission characteristics of the engine that working in the area of common conditions of the Universal Characteristics have a greater improvement, that fit the target of the manufacturers'requirements. After the critical MAP calibration, through bench test, the paper has a detailed analysis of the injection pressure and timing, the pre-injection parameters that effect on engine combustion process, economy and emissions performance, and make a contrast analysis on the diesel power, economy and emission characteristics of high-pressure common rail injection system between after and before optimization of parameters. The results shows that, after the optimization, the engine torque at low speeds increased significantly, particularly within the speed of 1400-2000r/min, but the fuel consumption has a little increase in this stage; at the high engine speed, the value of torque almost unchanged, but the fuel consumption has a greater improvement; the optimized emissions of NOx have a greatly improve, the value decreased about 10%; in the low speed, because increased the fuel injection volume, HC and CO emission is also increased, but in the middle and high speed, HC and CO emission have an improve.Using the tool of vehicle performance simulation software GT-DRIVE on the test vehicle's power-train to match the performance, and the method of basing on control over of Universal Characteristics, to improve and optimize the performance of engine to fit the needs of vehicle traffic. The results shows that:for the engine developed by this paper, a reasonable selection for the ratio of transmission of the power-train can improve the fuel economy, but make some power loss; for certain transmission, by the method of improving the Universal Characteristics that realization through matching variable pressurization device, and using the technology of cold and EGR, to effectively improve the vehicle dynamic property, fuel economy and emission characteristics; comparing with the original car's performance, at the precondition of dynamic property, the vehicle economy has a great improvement, and emissions regulatory requirements can be achieved.