为提高柴油机节能减排的效果,简要分析了多次喷射形式及其作用,依据车辆在不同路况运行,确定了车辆对应的6种柴油机典型工况.提出了基于工况排放值约束的多次喷射分配方法,采用工况排放分摊率确定典型工况的排放限值,进行喷射次数和变化喷射组合寻优,最后结合4JB1高压共轨柴油机台架试验,以氮氧化物和烟度为衡量参数,兼顾燃油消耗率的变化,分析不同喷射组合对柴油机排放的影响.结果表明:怠速工况和中速大负荷工况宜用2次喷射,低速小负荷工况和中速中负荷工况宜用3次喷射,中速小负荷工况宜用4次喷射,高速大负荷工况宜用1次喷射,说明基于工况排放值约束的多次喷射分配方法是有效的.

为说明高压共轨系统燃油温度变化对喷油量的影响,进行了不同燃油温度下的喷油参数修正计算.首先简要分析了高压共轨系统燃油流动传热特征,依据柴油机工作环境温度范围,提出了确定基准温度的方法,然后运用流体传热计算方法,推导出了喷油量和喷油压力的修正量计算公式;最后结合实例,给出了基准温度下的喷油压力和喷油量的基准脉谱,计算了不同温度下燃油喷油压力和喷油量的修正脉谱;结果表明:50℃燃油温度的喷油量修正量计算值与测试值的相对误差在14％以下,80℃燃油温度的喷油量修正量计算值与预测值的相对误差在9％以下,说明喷油参数修正计算方法是有效的.

To improve displacement amplifying performance of piezoelectric injector,dynamic performance of Hydraulic Coupling Displacement Amplifier (HCDA)is studied.Work principle and amplification re-quirement of HCDA is briefly analyzed,mathematic model of dynamic process of HCDA is presented by fluid dynamic method,simulation model of HCDA is founded based on AMEsim software,the accuracy of simulation model is evaluated by data comparison with experimental measurement and simulation calcula-tion,effect on small piston displacement by fluid factor and structure factor is discussed with simulation model.The result shows that fluid compression is determined by volume of hydraulic coupling chamber for a given fluid,5 μm piston clearance can meet leakage demand of hydraulic coupling chamber,the effect on small piston displacement by piston diameter and large piston’s spring preloaded force is large, the effect on small piston displacement by coupling chamber volume is little.

To meet measurement demand of fuel injection characteristics in electronic controlled injector,automatic measurement of needle lift in electronic controlled injector is studied.Based on that structure and work principle of electronic controlled injector are briefly analyzed,non-contact measurement method for needle lift of laser sensor is presented,measurement system for injector needle lift is constructed,measurement principle,hardware selection and software design are described.And measurement experiment is made on common rail fuel injection bench with high pressure.Test results show that the measurement method can meet the demands of fuel injection characteristics in electronic controlled injector.

To broaden the range of hardware in loop simulation for electronic controlled unit in application, a study on model simulation of electronic unit pump diesel engine oriented to control is made, the requirements and selection of simulation model oriented to control in electronic unit pump diesel engine are provided, and the model of simplified nonlinearity in diesel engine and electronic unit pump system are established in Matlab/Simulink. Model verification shows that this model can achieve fairly good accuracy. With the calculation time and parameter as evaluation index, different calculation steps and methods affecting the model output are analysed and compared. Real model is applied into hardware-inloop simulation test, its results show that the model can perform real-time ECU hardware-in-loop simula- tion test accurately.

The significance analysis of electronic control diesel engine parameter was researched with the orthogonal design method.The variance analysis method of orthogonal design was explained,the interaction orthogonal table was designed and the fuel consumption of diesel engine under rated conditions was acquired based on different schemes.Through the variance analysis method of orthogonal design,the influences of fuel supply advance angle,intake valve opening timing,exhaust valve opening timing and interaction between them on fuel consumption were analyzed and the significant degree of parameter under rated conditions was determined.

In order to select the interval of the plunger matching parts accurately,the requirements of the plunger matching parts of the fuel injector are briefly introduced. The influence factors of the high pressure oil pressure are analyzed. The mathematics model of the pressure and leakage of the plunger matching parts is given. The deformation of the plunger matching parts of electric controlled fuel injector of a certain diesel engine is analyzed with ANSYS simulation software. Compared with the deformation and matching interval changes under different conditions,according to the deformation,the relative leakage is calculated. Taken the deformation and leakage as the index,the reasonable program of the interval plunger matching parts is given.

为了优化电控柴油机燃烧过程控制,进行了燃烧过程状态参数压力指标的研究,分析了柴油机燃烧压力涵盖信息,引入压力差曲线方法表述燃烧过程,提出了压力差曲线特征参数概括燃烧过程,并构建了柴油机燃烧压力动态测试实验平台,结合4100型共轨柴油机的实验数据,分析了压力特征参数与柴油机控制参数、输出指标的关系。结果表明,燃烧压力指标能够反映柴油机的性能指标,成为实时反映燃烧过程的标志。

To improve the controlled effect of common rail pressure of high pressure common rail system, dynamic simulation for common rail pressure control was studied. The demand of common rail pressure control and simulating mechanism for PID control was analyzed briefly, and calculating model of common rail pressure was given with mixing way of hydraulic pressure model and flux boundary, and by AMESim hydraulic simulation software, dynamic simulation module for common rail pressure control was constructed, the control effect of control parameter, control duration and variable goal were compared respectively. Its result shows that the model can meet controlled demand of common rail pressure and reflect controlled effect of different parameter.

To meet the demand of teaching experiment in electronic controlled diesel engine,a general test bench for electronic controlled injection system is designed.The system structure,performance and characteristics of two types of electronic controlled injection system such as high pressure common rail,electronic unit pump are simply sketched.The overall scheme of the universal device is presented,the basic group of high pressure common rail,electronic unit pump,electronic controlled system and rotation speed and phase signal of cam disk are also provided.The controlling and monitoring software are programmed.By incorporating the result of partial control test,the feasibility of the electronic controlled universal device is proved.

The controlling of rail pressure of high pressure common rail diesel engine is studied. The frequency of the controlling single for pressure controlling valve, the period of verifying the control single and the methods of pressure sampling, controlling and filtering are investigated. It is proved that the strategies of using fixed interval phase sampling, fixed interval time interrupt controlling; arithmetic mean filtering could control the rail pressure at any value on any engine working conditions. The corrections of rail pressure at different conditions are designed. The sampling, controlling and corrections strategies of rail pressure were validated by experiment on engine test bench.

To facilitate the calibration process of electronic-controlled injector,a study on the calibration of fuel quantity and buildup of basic MAP was made.Chief factors affecting fuel injection consistency and identity were analyzed.A method for fuel injection consistency and identity improvement was designed by controlling the common rail pressure fluctuation and modifying the fuel injection pulse.The initial fuel injection MAP was achieved by the method of variable step interpolation,then the accuracy of the basic fuel injection MAP was tested.A test on an engine equipped with the calibrated common rail electric control injection system was carried out.The experimental results proved the rationality of the initial fuel injection MAP.

To obtain high signal-noise ratio signal of cylinder pressure in diesel engine,de-noising processing is presented by using nonlinear discrete time wavelet transform(DTWT).After the article analyzing high frequency noise and Gauss white noise existing in the cylinder pressure signal,the Donoho's soft-threshold de-noising method is firstly used to wipe off the Gauss white noise,the effect of which is superior to that of low pass filter and that of nine-dot smoothing way.Then based on multi-resolution analysis theory,the noise amplitudes of different frequency segments are calculated.Finally high frequency noise is reduced by the wavelet anti-transform algorithm and the cylinder pressure signal can be restored.Result shows that the presented method can denoise the cylinder pressure signal effectively.

The correction methods and matching strategy of fuel quantity were studied with the high pressure common-rail diesel engine.The influences of processing precision difference of the individual injector,diversity of the injector driven current and the pressure fluctuation affecting the coherence of the injection quantity were analyzed.The injection fuel quantity was corrected by feed-back control of the driven current and compensation of the energizing pulse.By analyzing the engine operation point,the matching strategy of fuel quantity on common-rail diesel engine was designed.The fuel quantity MAP was calibrated with an asymmetric step according to the frequency and importance of the engine operation.Finally,experiments were done on a test bench to verify the correction strategies.Experimental results show that the control and compensation strategies could improve the coherence of the injection fuel quantity.

A fuel system evaluation method was introduced to select the proper high pressure injection system for diesel engines.Using this method,the second generation common rail system of BOSCH Company was selected for use in the 4JB1 diesel engine.Based on this common rail system,a fuel supplying model was built using AMESim.The model included a high pressure pump sub-module,a pressure control valve sub-module,an injectors sub-module,and a connecting pipes sub-module.Through model simulation,the influences of parameters(e.g.,rail volume,high pressure pipe length and diameter) on pressure fluctuations and pressure building were studied.Rail-pipe system parameters were selected based on simulation results.Experimental results show the rail-pipe parameters could satisfy the needs of rapid pressure response and low pressure fluctuations for common rail diesel engines.

To meet the demand of high pressure common rail system equipped in high-power diesel engine, design and study on common rail line for high pressure common rail injection system is made. A sketch of high pressure common rail injection system for a certain type of military diesel engine is presented. According to the requirement of diesel engine and common rail structure, a dual-rail typed line is provided to suit the arrange space, different structure parameter of common rail line is calculated and the simplified simulation model of dual common rail system is built with AMESIM software. Common rail pressure undulation change is analyzed by the model in the condition of different parameter, a reasonable parameter of dual common rail is obtained and the result indicates that this method can provide reasonable parameter for the common rail structure.

A fuel injection control strategy for high pressure common rail diesel engine was designed based on the electric control unit(ECU) with the high performance microcontroller MPC555.The contro1 software was designed by modularization method according to various operation conditions of diesel engine.The software modules included the fuel quantity control module,rail pressure control module,management module for point of engine operation(POP),four stage start procedure control module,fault handling module and so on.By analyzing the frequency and importance of the POP,the control MAP was designed by using variable step and equal step.Finally,the experiments were conducted on test bench to verify the feasibility and reliability of the control strategies and to optimize the emission performance of the engine.Experimental results show that the expected control effect is achieved and the engine can reach the EURO-Ⅲ emission standard.

In order to meet the demand of dynamic acquisition in diesel engine,study on dynamic acquisition of cylinder pressure based on digital signal processor(DSP)was conducted.The acquisition method and data process,data communication of dynamic acquisition were proposed,partial acquisition area between 50°CA(crank angle)before top dead center(TDC)and 100°CA after TDC has been presented.Digital signal processor(DSP)and high speed USB(universal serial bus)were introduced into dynamic acquisition,hardware and software for dynamic acquisition system have been designed.The bench test for acquisition performance and stability of this system was finished.Test result showed that dynamic acquisition system of cylinder pressure based on DSP could meet the requirement of diesel engine.

After high pressure common rail injection system was introduced into a diesel engine,an investigation on combustion system parameter matching of the diesel engine was conducted.The demand of high pressure injection system for injection nozzle,combustion chamber and intake vortex was analyzed.In-cylinder pressure and power per liter under different compression ratio were computed by means of ideal gas compression equation and calculation formula of power per liter.According to the experimential design range of combustion chamber structure,several different re-entrant type combustion chambers were designed in order to fit different compression ratio.Basic parameters of five and six hole nozzle were calculated under maximal fuel amount and injection pressure condition.Vortex ratio needed by the nozzle parameter was calculated primarily based on the principle of optimal vortex ratio.The different schemes of combustion system were investigated on a diesel engine bench by using a matching method of single component sequence.The test results show that six hole nozzle,shallow bowl combstion chamber with larger diameter and vortex ratio 2.0 is more reasonable parameter for this diesel engine.

To meet the electronic control demand of high-power diesel engine, research on the control for electro-hydraulic injection timing actuator is conducted. The overall scheme and local closed-loop control strategy for injection timing angle are presented. The buildup of controlling hardware, software control and acquisition algorithm are introduced. A control model and algorithm is analyzed. The test result shows that this system can meet operational demand of diesel engine.