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首页> 外文学位 >Effect of intake valve closure timing on effective compression ratio and gas exchange process of a modern diesel engine.
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Effect of intake valve closure timing on effective compression ratio and gas exchange process of a modern diesel engine.

机译：进气门关闭正时对现代柴油机有效压缩比和气体交换过程的影响。

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摘要

Advanced combustion strategies including premixed charge compression ignition (PCCI) and lifted flame combustion are promising strategies for meeting increasingly stringent emissions regulations and improving fuel efficiency in next generation powertrains. In order to promote and implement these strategies closed-loop control of the gas exchange process and combustion is critical. Variable valve actuation (VVA) can play a key role in determining and controlling inputs to the combustion process. Modulation of intake valve closure (IVC) timing dictates the effective compression ratio (ECR) and influences the total amount of charge trapped inside the cylinder, and in doing so allows manipulation of the concentration and temperature history of the reactants prior to and during the combustion process. A validated whole engine model for a 6.7 liter six cylinder, turbocharged diesel engine with cooled exhaust gas recirculation (EGR) was used to investigate the gas exchange process behavior for steady state engine operation. The interaction between the primary actuators of the air handling system of a conventional modern diesel engine; the variable geometry turbocharger (VGT) and EGR valve, was analyzed at two different operating points using the model. The effect of different actuator positions and their coupled interactions was investigated via generation of charge flow versus EGR fraction diagrams from both simulation predictions and experimental data. The observations showed an increase in charge flow when the VGT position was modulated from open to close for a constant EGR valve position. There was also a slight increase in EGR fraction due to increase in pressure at turbine and EGR valve inlet as VGT closed. Similarly, an increase in EGR fraction with EGR valve position modulation was observed along with a slight reduction in charge flow, which was explained by reduction in turbine inlet pressure due to reduced restriction in exhaust path.;The effect of intake valve closing (IVC) event timing modulation on effective compression ratio (ECR) and gas exchange process was also investigated. The motivation behind this analysis was to explore the control authority of IVC modulation on the gas exchange process and ECR for implementing advanced combustion strategies including Premixed Charge Compression Ignition (PCCI) and lifted-flame combustion in steady state. A reduction in ECR with IVC modulation was observed. It was also shown that a particular ECR-reduction could be achieved via an early or late IVC timing modulation. The gas exchange process showed a decrease in charge flow with reduction in effective compression ratio. The EGR fraction also reduced accordingly. The trends were confirmed by experimental data from Cummins ISB engine with a VVA system. The electro-hydraulic VVA used is only one of its kind in academia, with control software development and implementation done at Herrick labs, Purdue University. The engine data with VVA for six cylinders showed good agreement with simulation results. The work described in this thesis established steady state control authority of IVC timing, EGR and VGT positions on ECR. It also establishes the effect of ECR modulation on gas exchange process of a modern diesel engine with data validation from a multi-cylinder engine with VVA capability. A method to estimate temperature at top dead center is also described and validated against simulation re- sults. Candidate control structures for both steady state and transient operation are also suggested in this thesis. The work described in this thesis is a first step towards demonstrating PCCI on a multi-cylinder engine with VVA capability for steady state operation, and lays the ground work for model investigation and control development for transient engine operation for promotion of advanced combustion modes.
机译：先进的燃烧策略，包括预混合增压压燃（PCCI）和提升火焰燃烧，是满足日益严格的排放法规并提高下一代动力总成燃料效率的有前途的策略。为了促进和实施这些策略，对气体交换过程和燃烧的闭环控制至关重要。可变气门驱动（VVA）可以在确定和控制燃烧过程的输入中发挥关键作用。进气门关闭（IVC）时机的调节决定了有效压缩比（ECR），并影响了气缸内截留的装料总量，从而可以在燃烧之前和燃烧期间控制反应物的浓度和温度历史处理。经过验证的6.7升六缸涡轮增压柴油机的整体发动机模型具有冷却的废气再循环（EGR），用于研究稳态发动机运行时的气体交换过程性能。传统现代柴油机的空气处理系统的主要执行器之间的相互作用；使用该模型在两个不同的工作点分析了可变几何涡轮增压器（VGT）和EGR阀。通过从模拟预测和实验数据生成电荷流与EGR的关系图，研究了不同执行器位置及其耦合相互作用的影响。观察结果表明，对于恒定的EGR阀位置，当VGT位置从打开调节到关闭时，充气流量增加。由于VGT关闭时，涡轮机和EGR阀入口处的压力增加，EGR分数也略有增加。类似地，随着EGR阀位置调节，观察到EGR分数增加，充气量略有减少，这可以通过减少排气路径限制而导致涡轮进气压力降低来解释。;进气门关闭（IVC）的影响还研究了有效压缩比（ECR）和气体交换过程中的事件正时调制。该分析的目的是探索IVC调制在气体交换过程和ECR上的控制权，以实施先进的燃烧策略，包括预混合装药压缩点火（PCCI）和稳态火焰提升燃烧。观察到具有IVC调制的ECR降低。还显示出可以通过早期或晚期IVC定时调制来实现特定的ECR降低。气体交换过程显示装料流量减少，有效压缩比降低。 EGR分数也相应降低。康明斯ISB发动机和VVA系统的实验数据证实了这一趋势。所使用的电动液压VVA只是学术界中的一种，控制软件的开发和实施是在普渡大学的Herrick实验室完成的。六个汽缸的VVA发动机数据与仿真结果吻合良好。本文所描述的工作建立了IVC定时，ECR上的EGR和VGT位置的稳态控制权限。它还通过具有VVA功能的多缸发动机的数据验证，建立了ECR调制对现代柴油发动机的气体交换过程的影响。还描述了一种估算上止点温度的方法，并针对仿真结果进行了验证。本文还提出了稳态和暂态运行的候选控制结构。本文所描述的工作是向具有VVA能力的多缸发动机进行稳态运行演示PCCI的第一步，为瞬态发动机运行的模型研究和控制开发奠定了基础，以促进先进的燃烧模式。

著录项

  • 作者

    Modiyani, Rajani S.;

  • 作者单位

    Purdue University.;

  • 授予单位 Purdue University.;
  • 学科 Engineering Mechanical.
  • 学位 M.S.E.
  • 年度 2010
  • 页码 138 p.
  • 总页数 138
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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