摘 要

在排放法规日益严格的今天，能够降低油耗以及排放的发动机技术显得尤为重要，缸内直喷技术有着良好的燃油经济性，缸内直喷汽油机（GDI汽油机）与传统的进气道喷射汽油机（PFI汽油机）相比，燃油经济性能够提高近20%。不过由于缸内直喷给可燃混合气混合时间过短等原因，GDI汽油机所产生的颗粒物也远远高于PFI汽油机。所以研究GDI汽油机颗粒物排放特性以及控制策略的重要性日益显著。本文就GDI汽油机的颗粒物排放及其动力性和其他排放物做了相关研究。

本文从两个方面展开研究。

一方面是针对GDI汽油机颗粒物排放特性的实验方面的研究分析，实验发动机是一台GDI四缸汽油机，实验以DMS500快速颗粒取样分析仪为主要仪器，改变发动机的工况，主要是改变转速和扭矩，采集在同转速不同扭矩下的颗粒物排放数据，包括颗粒物的总质量浓度和总数量浓度，以及核模态和聚集态两种形态的颗粒物的数量浓度。经过数据的汇总及分析后发现：（1）在低转速工况下的GDI汽油机排放颗粒物中，核模态颗粒物数浓度远远高于聚集态，且随着负荷增大，核模态颗粒物数浓度逐渐降低。（2）在部分负荷特性下，总颗粒物数量浓度随着转速的升高总体呈现下降的趋势，而在外特性下，GDI汽油机的颗粒物排放会随着转速的升高先略微下降，然后逐渐上升的趋势，并且外特性下的总颗粒物数浓度要高于同等速度下部分负荷特性的颗粒物数浓度。（3）在低负荷和高负荷下的颗粒物质量浓度比中等负荷的颗粒物质量浓度要高得多。

另外一方面是针对GDI汽油机的动力性以及其他排放物的研究，通过GT-Power软件建立一个GDI四缸汽油机的仿真模型，经过对标后，仿真分析不同电控参数对发动机性能的影响，这些电控参数包括燃空比、进气正时和点火时刻，所分析的影响主要是电控参数对输出扭矩的影响以及CO或者HC的影响。仿真后发现：（1）在扭矩分析上，三个电控参数对峰值扭矩影响最大的是燃空比，对高转速区域的扭矩影响最大的是点火提前角。（2）在排放分析上，燃空比主要影响CO排放，进气提前角主要影响HC排放，点火提前角主要影响的是NO_x的排放。

并在最后做了正交试验设计，完成仿真后，分析仿真结果，对GDI汽油机模型性能进行了优化。

关键词：缸内直喷汽油机、颗粒物、扭矩、排放物、GT-Power

Abstract

In the increasingly stringent emission regulations today, to reduce fuel consumption and emissions of engine technology is particularly important, in-cylinder direct injection technology has a good fuel economy, comparing with the direct injection gasoline engine (GDI engine) and the traditional Port Fuel Injection gasoline engine (PFI gasoline engine), fuel economy can improve nearly 20%. However, due to the direct injection of direct combustion to the combustible mixture is too short and other reasons, GDI gasoline engine produced by the particles are also much higher than the PFI gasoline engine. So the study of GDI gasoline engine particulate emission characteristics and the importance of control strategies become increasingly significant. This paper studies the particulate matter emissions and its dynamical and other emissions from GDI gasoline engines.

    This article is from two aspects of research.

    On the one hand, it is a research and analysis on the experimental characteristics of GDI gasoline engine particulate matter. The experimental engine is a GDI four-cylinder gasoline engine. The experiment is based on DMS500 rapid particle sampling analyzer as the main instrument, changing the working condition of the engine, mainly changing the speed and torque , The particulate matter emission data collected at different torques at the same speed, including the total mass concentration and total concentration of the particles, and the number of particles in both the nuclear and aggregated states. After the data were collected and analyzed, it was found that: (1) the concentration of nuclear particles in the GDI gasoline engine was much higher than that in the aggregated state, and with the increase of the load, the number of nuclear modal particles The concentration gradually decreased. (2) Under the partial load characteristics, the total particulate matter concentration tends to decrease with the increase of the speed. Under the external characteristics, the particulate matter emission of the GDI gasoline engine will decrease slightly with the increase of the speed, and then gradually increase And the total number of particles in the external characteristics is higher than the concentration of the particles at the same velocity. (3) The mass concentration of particulate matter at low load and high load is much higher than that of medium load.

    On the other hand, the research on the dynamical and other emissions of GDI gasoline engine is carried out. The simulation model of GDI four-cylinder gasoline engine is established by GT-Power software. After the calibration, the influence of different electronic control parameters on engine performance is simulated and analyzed. The electronic control parameters include fuel-air ratio, intake timing and ignition timing. The influence of the analysis is mainly on the influence of the electronic control parameters on the output torque and the influence of CO or HC. Simulation found that: (1) in the torque analysis, the three electronic control parameters on the peak torque is the greatest impact on the air-fuel ratio, the high torque range of the greatest impact on the ignition advance angle. (2) In the emission analysis, the fuel-air ratio mainly affects the CO emission, the intake advance angle mainly affects the HC emission, and the ignition advance angle mainly affects the NO_x emission.

Finally, the orthogonal experiment design is done. After the simulation is completed, the simulation results are analyzed and the performance of the GDI gasoline engine model is optimized.

Keyword:GDI engine,particulate matter,torque,emission,GT-Power

目录

摘要 I

Abstract II

目录 IV

第1章 绪论 1

1.1 研究背景 1

1.2 国内外研究现状 1

1.3研究内容 3

第2章 GDI汽油机仿真模型的建立与标定 4

2.1 GT-Power软件介绍 4

2.2 GDI汽油机仿真模型的建立 4

2.2.1 气门模块 4

2.2.2 喷嘴模块 5

2.2.3气缸模块 6

2.2.4 发动机曲轴箱模块 7

2.2.5 GDI四缸汽油机仿真模型 8

2.3 GDI汽油机仿真模型的标定 9

2.4 本章小结 10

第3章 某GDI四缸汽油机颗粒物排放台架实验 11

3.1实验发动机 11

3.2 实验仪器 11

3.3 实验工况 12

3.4 实验结果与讨论 12

3.4.1 低转速下的颗粒物特性 12

3.4.2 转速对颗粒物浓度的影响 13

3.4.3 负荷对颗粒物浓度的影响 14

3.5 本章小结 15

第4章 GDI汽油机参数优化仿真研究 17

4.1 燃空比（F-A Ratio）对GDI汽油机的影响 17

4.1.1 燃空比Case的建立 17

4.1.2 燃空比对扭矩的影响仿真结果及分析 18

4.1.3 燃空比对CO排放影响的仿真结果及分析 19

4.2.1 进气提前角Case的建立 20

4.2.2 进气提前角对扭矩的影响仿真结果及分析 21

4.2.3 进气提前角对HC排放物浓度的影响 22

4.3 点火提前角对GDI汽油机的影响 23

4.3.1 点火提前角Case的建立 23

4.3.2 点火提前角对扭矩的影响仿真结果及分析 24