Research on the Control Strategy of Variable Nozzle Turbocharger for Natural Gas Engine

A variable nozzle turbocharger (VNT) was applied to a 2.2-liter L4 natural gas engine,and a VNT control system was designed to operate it.Based on VNT matching test results,a VNT control strategy was studied,in which VNT adjustment is carried out through pre-calibrated VNT handling rod position,combined with a closed-loop target boost pressure feedback using proportional-integral-derivative(PID) algorithm.Experimental results showed that the VNT control system presented in this thesis can lead to optimized ...     

Optimizing Spray and Combustion in Diesel Engine by Multidimensional Numerical Simulation

The calculation of spray and combustion in diesel engines is described by using the softwares FIRE and BOOST. The application of the resulting computational method to the simulation of fuel spray and breakup, mixture formation and combustion in a heavy duty diesel is presented. According to detailed insight into the governing processes provided by the simulation results, various aspects of the dependence of the spray propagation and combustion on the chamber geometry and spray angle are discussed. Then, global cylinderaveraged pressure traces are extracted from the space and time resolved field quantities and compared to incylinder pressure measurements. Finally, an optimized configuration of the chamber geometry and spray angle with a new injection rate of higher injection pressure is proposed.     

Optimal tracking control for automatic transmission shift process

In order to improve the shift quality, a linear quadratic optimal tracking control algorithm for automatic transmission shift process is proposed. The dynamic equations of the shift process are derived using a Lagrange method. And a powertrain model is built in the Matlab/Simulink and verified by the measurements. Considering the shift jerk and friction loss during the shift process, the tracking trajectories of the turbine speed and output shaft speed are defined. Furthermore, the linear quadratic optimal tracking control performance index is proposed. Based on the Pontryagin's minimum principle, the optimal control law of the shift process is presented. Finally, the simulation study of the 1-2 upshift process under different load conditions is carried out with the powertrain model. The simulation results demonstrate that the shift jerk and friction loss can be significantly reduced by applying the proposed optimal tracking control method.     

Investigation of the optimum differential gear ratio for real driving cycles by experiment design and genetic algorithm

Experiment statistical method and genetic algorithms based optimization method are used to obtain the optimum differential gear ratio for heavy truck that provides best fuel consumption when changing the working condition that affects its torque and speed range. The aim of the study is to obtain the optimum differential gear ratio with fast and accurate optimization calculation without affecting drivability characteristics of the vehicle according to certain driving cycles that represent the new working conditions of the truck. The study is carried on a mining dump truck YT3621 with 9 forward shift manual transmission. Two loading conditions,no load and 40 t,and four on road real driving cycles have been discussed. The truck powertrain is modeled using GT-drive,and DOE-post processing tool of the GT-suite is used for DOE analysis and genetic algorithm optimization.     

不考虑液相化学反应的苄基叠氮复合柴油液滴蒸发特性仿真

为研究物性参数差异对苄基叠氮复合柴油液滴蒸发特性的影响,选择正十六烷作为柴油的替代物,在不考虑液相化学反应的前提下构建了苄基叠氮-正十六烷多组分液滴蒸发模型.然后利用该模型分析了液滴的蒸发过程,研究了苄基叠氮质量分数和环境温度对液滴蒸发过程的影响.结果表明,苄基叠氮-正十六烷液滴蒸发可分为瞬态加热阶段、混合蒸发阶段和平衡蒸发阶段.苄基叠氮由于其相对正十六烷较高的饱和蒸气压、较小的定压比热容以及较大的蒸气相扩散系数,因而具有较快的蒸发特性.随着苄基叠氮质量分数的增加,液滴蒸发速率不断提高;随着环境温度的升高,液滴升温速率不断增大,平衡蒸发温度不断升高,液滴蒸发速率不断增大,但是这一变化趋势并不与温度呈线性关系.     

液压驱动式泵-喷嘴系统特性研究

对一种电子控制液压驱动式泵-喷嘴供油系统进行了建模与仿真,在AMEsim环境下使用机械、液压和控制部件的标准元件搭建仿真模型,用一维集总参数法进行仿真计算.利用试验测出的柱塞升程和柱塞腔内压力以及循环供油量检验模型的准确性和精度,在此基础上通过对仿真模型的优化,计算了不同控制参数下的喷油规律,对该喷油器的改进设计及其与发动机的合理匹配和供油系统控制策略的研究具有一定的指导意义.     

某富水断层对隧道稳定性及涌水影响敏感性分析

以武九高楼山公路隧道突涌水灾害为研究背景,针对其以断层破碎带为主控因素的隧道围岩稳定及突水问题展开调研和数值分析研究,以期为突涌水治理措施的制定提供参考。基于ＦＬＡＣ３Ｄ有限差分法及流固耦合分析原理,研究了隧道埋深Ｈ、地下水位高度ｈ、围岩级别Ｓ、侧压力系数Ｋ０、断层宽度Ｗ、断层与隧道相对间距ｄ／Ｄ、断层与水平面夹角θ等７个因素对隧道围岩稳定性及涌水量的影响规律,并基于公路隧道规范中建议的隧道相对收敛变形及涌水量等级,对围岩稳定性及涌水等级进行评价。结果表明:围岩级别Ｓ对隧道变形、塑性区、涌水量影响最大,其次为侧压力系数Ｋ０,再次为断层与隧道相对间距ｄ／Ｄ和断层宽度Ｗ;不敏感的影响因素为:隧道埋深Ｈ、地下水位高度ｈ及断层与水平面夹角θ。地层条件及断层因素是隧道突涌水的主控因素,治理措施中应优先考虑地层的加固和限量排放双重措施。     

ECU的多任务、多数据结构标定系统的研究开发

设计了一套集成了在线标定和嵌入式数据采集功能的在线标定系统.标定系统基于Windows平台,采用独特的数据流格式、数据属性文件和通信协议.在对在线标定系统与柴油机的MC68376单片机电控单元进行离线联机调试后,对JS125汽油机进行了标定实验.实验表明:该标定系统具有较好的扩展性、稳定性和可靠性,能够适应多种单片机和控制系统编程语言,简化了ECU通讯程序.     

某型柴油机高压共轨喷油器结构改进仿真分析

针对某型柴油机共轨喷油器改进设计的需求,建立了喷油器的数值仿真模型,研究了喷油器针阀质量、控制腔容积及供油道长径比对喷油器特性的影响.研究表明在保证针阀结构强度的情况下,针阀质量应该更小;控制腔容积在满足针阀升程要求等条件下也应更小;在确定长径比的条件下,合理安排喷油器的尺寸结构,适度增加供油管的长度和直径可以降低喷油器内部的压力波动.研究为该型喷油器的改进设计提供了技术支撑.     

用"缸平移"法提高柴油机模型实时性的方法研究

为了解决柴油机ECU硬件在环仿真时,柴油机模型的精确度和实时性的矛盾,提出了基于充排法的柴油机＂缸平移＂建模方法.在Matlab/Simulink中建立基于充排法的柴油机模型,假设发动机全部气缸以相同方式工作,通过＂缸平移＂法获得＂缸平移＂模型.分别将充排法的发动机模型和＂缸平移＂模型下载到dSPACE Autobox中进行实时仿真,试验表明应用＂缸平移＂方法建立的柴油机模型可以使系统的仿真速度提高三倍.