基于扭矩的汽油机控制模型开发及验证

开发了基于扭矩的控制模型,包括传感器信号处理模型、扭矩模型、怠速模型、节气门模型、空气系统模型、起动控制模型等。为了验证基于扭矩的控制系统,将基于扭矩的控制系统写入自主开发硬件,在发动机台架上进行了测试。结果表明发动机起动迅速,起动时间在3 s以内。怠速转速稳定,怠速转速波动在±10 r/min以内。进怠速和出怠速时过渡平滑。瞬态工况过渡平滑,发动机最高转速运转稳定。基于扭矩控制模型扭矩控制精度在5%以内。试验结果表明自主开发的系统控制功能基本完备,能较好地满足扭矩控制要求。     

怠速转速对整车燃油经济性的影响

用理论与试验相结合的方法对整车降低怠速转速后的节油效果进行了研究,结果表明怠速转速降低50r/min,怠速油耗降低6%左右。在城市道路行驶怠速工况较多,降低怠速转速后整车节油效果较好,但是NEDC测试循环怠速工况时间短且怠速油耗量小,加之测试与设备误差等原因,很难直接测试出降低怠速的节油效果,为此提出了采用NEDC工况拆解法来计算降低怠速转速后的油耗与节油效果。     

怠速时车身抖动原因及排除方法

车身在怠速时抖动明显,一般要先观察热车前提下怠速时转速表是否稳定。若转速表显示不稳定,则可能的故障原因如下:1.怠速开关不闭合故障分析:怠速触点断开,ECU便判定发动机处于部分负荷工况状态。此时ECU根据空气流量计和曲轴转速信号确定喷油量。而此时发动机实际上却是在怠速工况下工作,进气量较少,造成混合气过浓,转速上升。当     

汽油机减轻排气污染的调整

1怠速工况的调整 在怠速工况下,发动机转速越低,混合气的均匀性越差,气缸内残留废气的相对比例也越大,越容易导致混合气的不完全燃烧.根据怠速工况下的这一燃烧机理,可在标定的发动机怠速转速范围内,调整怠速空气调节螺钉和节气门调整螺钉,以供给较稀的混合气.但怠速转速应尽量调至规定的上限值,转速越高,废气浓度越低.     

摩托车化油器技术漫谈化油器的典型故障成因分析与维护第七讲(下)

过渡不良摩托车在起步加速行驶的过程中,化油器从怠速油系供油逐渐减少过渡到主油系供油不断增加。为使怠速油系与主油系之间供油衔接圆滑,设置了过渡油系,以保证摩托车起步过程的平顺性。过渡不良的现象:起步加速过程中,随着油门的开大发动机转速波动较大或熄     

浅谈四冲程发动机热车怠速熄火的起因及检修(上)

发动机怠速,顾名思义即发动机在无负荷工况下的最低稳定转速,它是衡量发动机工作良好与否的主要特征之一.正常情况下,发动机怠速应能在15分钟内稳定于标定转速±100r/min以内.随着发动机运动零件的不断磨损,其怠速性能也在发生变化,其中热车怠速熄火故障占据相当的比例.由于影响发动机怠速工况的因素较多,给故障分析和排查带来了一定的难度,为此,本文拟对该故障的起因和检修注意要点作简要介绍,供广大摩托车爱好者和维修人员参考.     

小排量汽油机电控管理系统怠速稳定性研究

开发了发动机电控管理系统,通过研究怠速工况下各个时段的不同特征,分析了怠速稳定性控制要素和怠速排放要求;结合专家控制系统、变参数PID控制、预测控制、怠速自适应控制,研究了汽油机怠速控制的各种先进控制策略。采用不同的先进控制算法对怠速工况的控制进行试验调试,对各个控制参数进行精确整定。根据不同的外在负荷对怠速工况进行优化控制,同时采用调节点火提前角实现扭矩波动平衡控制,实现了发动机的怠速最佳稳定控制。     

怠速不良故障排查法

怠速是发动机在无负载工况下的最低空载稳定转速，是衡量摩托车工作是否良好的主要特征之一。发动机怠速不良故障通常是由燃油系统、点火系统和机械部分等故障引起的。怠速不良故障通常表现为无怠速、怠速不稳及怠速过高，本文从这3个方面进行分析和总结，以供广大读者和摩托车维修人员参考。     

增压直喷汽油机配气相位确定方法的研究

针对增压直喷汽油机的特点,设计了配气相位的目标要求及确定方法,对常用工况进行了热力学分析,设计了满足目标要求的气门升程曲线,结合怠速稳定性和气门与活塞运动干涉的研究,确定了配气机构安装相位。试验表明,该分析方法在怠速时可实现怠速转速波动率有效下降,且在各转速工况实现VVT相位变化最大,避免气门与活塞的运动干涉。     

轻骑K系列发动机怠速不良原因及排除方法

发动机怠速即发动机最低空载稳定转速,它是衡量发动机工作良好与否的主要标志,是国标上规定的摩托车及发动机的主要性能之一,同时还规定了怠速实验方法和怠速衡量标准。试验方法是:将发动机置于空挡,节气门置于怠速位置,交替调整怠速混合气体调节螺钉,测量其转速及转速波动量,然后,突然开大节气门,发动机不应熄火。对发动机最低空载稳定转速的要求是:发动机应能在最低空载稳定转速(怠速)下稳定运转15分钟,其转速波动     

高压共轨柴油机怠速控制策略研究

柴油机由于怠速时供油量较小,各缸供油量不同和每缸供油量的波动很大,在不同的冷却水温下保持稳定转速所需的喷油量不同,会造成燃烧过程恶化、排放性能变差。因此,分析了车用高压共轨柴油机怠速不稳定因素,采取了多种措施,如怠速开环和闭环控制、各缸均衡控制以及多段喷射等来减小怠速时的转速波动和运转噪声,通过试验验证了这些方法的有效性,从而提高了柴油机的怠速性能。     

Development of an idle speed engine model using in-cylinder pressure data and an idle speed controller for a small capacity port fuel injected SI engine

An idle speed engine model has been proposed and applied for the development of an idle speed controller for a 125 cc two wheeler spark ignition engine. The procedure uses the measured Indicated Mean Effective Pressure (IMEP) at different speeds at a constant fuel rate and throttle position obtained by varying the spark timing. At idling conditions, IMEP corresponds to the friction mean effective pressure. A retardation test was conducted to determine the moment of inertia of the engine. Using these data, a model for simulating the idle speed fluctuations, when there are unknown torque disturbances, was developed. This model was successfully applied to the development of a closed loop idle speed controller based on spark timing. The controller was then implemented on a dSPACE Micro Autobox on the actual engine. The Proportional Derivative Integral (PID) controller parameters obtained from the model were found to match fairly well with the experimental values, indicating the usefulness of the developed idle speed model. Finally, the optimized idle speed control algorithm was embedded in and successfully demonstrated with an in-house built, low cost engine management system (EMS) specifically designed for two-wheeler applications.     

基于PID算法的车用天然气发动机怠速闭环控制研究

利用自行改装的天然气发动机及自主研发的ECU和转速采集系统,采取增量式PID控制算法对发动机怠速进行单闭环和双闭环控制,并进行了试验验证及控制结果对比分析。台架试验表明:基于PID控制算法的怠速闭环控制有利于怠速的稳定,在单闭环基础上开发的双闭环控制能更有效地降低怠速波动量。     

基于扰动观测的智能驾驶主动抗扰纵向车速控制算法

为了减少智能驾驶车辆的纵向车速控制的时滞,提高主动抗扰性,提出一种基于扰动观测的纵向车速控制算法,并进行了实车验证。模型中,采用前馈控制模块,并提前输出控制量,来提高车速跟随的响应性;以主动抗扰控制(ADRC)模块作为反馈环节,采用扩张状态观测器(ESO)在线估计内外部扰动,并在控制端进行补偿,实现了对车速的精确闭环控制。在弯道、环岛等路况下进行了实车实验。结果表明:该算法可以在5 s内控制车速从怠速快速跟踪到目标车速,总体平均误差为0.17 km/h。因而,该算法较传统的比例积分微分(PID)有更好的响应性、控制精度和抗扰性。     

柴油机典型工况的电控喷油器多次喷射分配

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。     

Effect of Heavy-Duty Diesel Engine Operating Parameters on Particle Number and Size Distribution at Low Speed Condition

Experiments and simulations were used to investigate the effect of a range of engine operating parameters and fuel characteristics on the particle size and particle number (PN) concentration at low speed and idle speed condition. The occurrence, size, and concentration of particles were tested against a range of parameters including start of injection (SOI), common rail pressure, exhaust gas recirculation (EGR) ratio and load. The results showed that the homogeneity of the mixture had the greatest impact on particle size and number concentration. The performance of particle is different at different levels of load. The particle were of nucleation mode at idle condition, and the cold idle particles had a slightly larger diameter than those produced at hot idle. By using the diesel and under high load, at EGR ratios of less than 20 %, most particles were of nucleation mode. At EGR ratios exceeding 20 %, nucleation-mode particles were gradually replaced by accumulation-mode particles. At EGR ratios above 30 %, most particles were of the accumulation mode. Under the same load, gasoline compression ignition produced particles of smaller size and reduced particulate mass (PM). The use of gasoline extended ignition delay, as the high volatility and octane number of the fuel improved the homogeneity of the mixture. Finally, a linear relationship was found between PM and PN. The relative contribution of the different factors to the formation of nucleationor accumulation-mode particles was investigated.     

共轨柴油机起动油量控制策略优化及试验研究

在自主研发的基于Freescale 9S12 16位电控单元基础上,将共轨柴油机的起动阶段划分为起动初期、起动加速期、起动延伸期及稳定阶段分别进行控制。针对各个阶段的特点,提出各自的控制策略优化方案。利用Matlab/Simulink建立起动工况喷油量的仿真模型,离线仿真后在1台4JB1高压共轨柴油机上进行了起动油量的优化标定试验。试验结果表明,优化后的柴油机起动迅速可靠,转速过渡平稳。     

Effects of altitude on combustion characteristic during cold start of heavy-duty diesel engine

Altitude has a significant effect on combustion of heavy-duty diesel engines, especially during cold start. An experimental study on a heavy-duty diesel engine operating at different altitudes was conducted. Tests were based on a direct injection (DI) turbocharged diesel engine with intake and exhaust pressure controlled by the plateau simulation test system to stimulate altitude conditions including 0 m, 1000 m, 2000 m, 3000 m and 4000 m. Results indicated that the compression and expansion resistance moment reduced and the speed increased during the cranking period. The peak pressure of several cycles was increased during the start-up period; however, the expansion pressure dropped more and the indicated mean effective pressure (IMEP) reduced as the altitude rose. While at an altitude of over 2000 m, the peak pressure fluctuated obviously during the start-up period. The higher the altitude was, the more the fluctuation amplitude and cycle number increased and combustion instability enhanced, which resulted the start-up period time increasing at high altitude. When the altitude rose, the cycle-to-cycle variation of the peak pressure and speed fluctuation increased during the idle, the ignition and CA50 were delayed and the combustion duration was shortened. The effect of altitude on combustion characteristics of the diesel engine was more significant during the start-up period than during its idle period.     

顺序增压系统液压转换装置结构设计与评估试验研究

针对某增压柴油机,设计了一种带有液压执行机构转换装置的顺序增压系统,并通过台架试验评估该系统的性能。试验结果表明,带液压执行机构的顺序增压转换装置具备流量调节能力,可实现受控增压器的"寄存",进气阀和排气阀由自编的控制程序根据设定的开闭规律动作,在试验过程中工作稳定。     

Idle speed controller based on active disturbance rejection control in diesel engines

This study proposes a design for an idle speed controller to compensate for varying engine load and friction torque in passenger car diesel engines. An active disturbance rejection control (ADRC) framework, comprised of a disturbance compensator and a feedback controller, is applied to an idle speed controller to compensate for disturbances such as engine load and friction torque. In addition, a feedforward compensator is designed into the ADRC framework to improve disturbance rejection performance. The proposed controller is validated by engine and vehicle experiments and the experiment results are compared with a commercial controller.