高压共轨柴油机轨压控制策略研究

发布时间：2018-06-23 19:26

本文选题：高压共轨 + 柴油机　；参考：《吉林大学》2015年硕士论文

【摘要】：随着节能环保要求日益严格，高压共轨系统得到越来越多的应用。轨压控制策略是实现高压共轨系统燃油喷射系统喷射压力高、喷射次数多的前提。轨压控制要求稳态波动小，瞬态响应快，满足高压共轨柴油机起动、怠速、正常、加减速等稳态及非稳态工况下的需求。本文在实验室前期大量仿真、试验、分析的的基础上，使用一款基于MC9S12XEP100单片机的开放式电控单元进行高压共轨电控燃油喷射系统开发，作为完整柴油机电控系统的一部分。本文主要工作包括： 1．深入研究博世第二代共轨系统共轨、喷油器、高压泵等关键部件的工作原理，并基于此使用AMESim建立其一维仿真模型。利用详细子模型对喷油器喷油、喷油器回油、高压泵柱塞泄露等特性进行分析，为轨压控制策略建立提供依据。进行模型简化，提高模型运算速度。 2．使用MATLAB/Simulink/Stateflow建立高压共轨柴油机燃油喷射系统轨压控制策略模型，包括开闭环切换模块、目标轨压计算、前馈流量计算、PID反馈流量计算、流量转占空比模块等。进行联合离线仿真，确定前馈加反馈的轨压控制结构。 3．使用CodeWarrior集成开发环境完善轨压控制的信号采集处理、任务调度、输出驱动等，，使所设计的轨压控制策略能够在电控单元整体框架下正常工作。 4．建立由变频器、调速电机驱动的高压共轨燃油喷射系统泵台试验台架，进行一部分稳态及非稳态工况试验，验证了所设计的轨压控制策略的可行性，并对控制周期、控制步长、前馈控制、PID参数、PT滤波时间常数等进行初步的标定。最终在完整的高压共轨柴油机发动机台架上进行起动等复杂工况试验，对开环控制做进一步的标定。结果表明：在所研究的范围内，喷油器工作过程中产生的回油量与喷射脉宽和目标轨压正相关，增长基本成一条直线；喷油器喷油和回油量二者增长规律相似，二者合并可以作为一个前馈脉谱，也可以用一个公式计算；高压泵柱塞泄漏与目标轨压和温度正相关，可以作为另一个前馈脉谱，也可以拟合出一个公式进行计算；经过仔细标定的带有开闭环切换的基于前馈加反馈控制结构的轨压控制策略能够起到良好的控制效果，起动工况，起动开始0.92s之后，轨压就能从0MPa增大到40MPa；急加速及急减速工况，轨压能够在1.6s内快速变化30MPa；稳态工况，轨压最大波动在±3MPa范围内；满足高压共轨柴油机起动、正常、加减速等各个工况下的需求。
[Abstract]:With the increasingly stringent requirements of energy saving and environmental protection, high-voltage common rail system has been applied more and more. The control strategy of rail pressure is the premise of high injection pressure and multiple injection times of fuel injection system in high pressure common rail system. Rail pressure control requires small steady state fluctuation and fast transient response to meet the needs of high pressure common-rail diesel engine under steady and unsteady conditions such as starting idling speed normal acceleration and deceleration. On the basis of a lot of simulation, experiment and analysis in the early stage of the laboratory, an open electronic control unit based on MC9S12XEP100 single chip microcomputer is used to develop the high pressure common rail electronic fuel injection system, which is a part of the complete electronic control system of diesel engine. The main work of this paper is as follows: 1. The working principle of the common rail, injector, high pressure pump and other key components of Bosch's second generation common rail system is deeply studied, and based on this, the one-dimensional simulation model is established by using AMESim. The detailed sub-model is used to analyze the characteristics of injector, injector return and leakage of high pressure pump plunger, which provides the basis for the establishment of rail pressure control strategy. Using MATLAB / Simulink / Stateflow to establish the rail pressure control strategy model of high pressure common-rail diesel engine fuel injection system, including open closed loop switching module, target rail pressure calculation, Feedforward flow calculation pid feedback flow calculation, flow duty cycle module and so on. Combined off-line simulation to determine the feedforward and feedback rail pressure control structure. 3. Using CodeWarrior integrated development environment to improve rail pressure control signal collection and processing, task scheduling, output drive, etc. The designed rail pressure control strategy can work normally under the whole frame of the electronic control unit. 4. The pump bench of high voltage common rail fuel injection system driven by frequency converter and speed regulating motor is established. The feasibility of the designed rail pressure control strategy is verified by a part of steady and unsteady state tests, and the control cycle, control step size, feed forward control pid parameter and PT filter time constant are preliminarily calibrated. Finally, the open loop control is further calibrated on the complete engine bench of high pressure common rail diesel engine under complex operating conditions such as starting test. The results show that the fuel return produced by the injector is positively correlated with the injection pulse width and the target rail pressure, and the increase is basically a straight line, and the growth law of the injector oil injection and fuel return is similar. The combination of the two can be used as either a feedforward pulse spectrum or a formula, and the leakage of the plunger of the high pressure pump is positively correlated with the target rail pressure and temperature, and can be used as another feedforward pulse spectrum or can be calculated by fitting a formula. The rail pressure control strategy based on feedforward and feedback control structure, which is calibrated carefully with open and closed loop switching, can play a good control effect. The rail pressure can be increased from 0 MPA to 40 MPA after starting operation for 0.92s. In the rapid acceleration and deceleration conditions, the rail pressure can rapidly change 30 MPa in 1.6 s, and the maximum fluctuation of rail pressure in the steady condition is 卤3 MPA, which can meet the requirements of the high pressure common rail diesel engine under the starting, normal, acceleration and deceleration conditions.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK423

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