Comparison of in-cylinder combustion and heat-work conversion processes of vehicle engine under transient and steady-state conditions
Comparison of in-cylinder combustion and heat-work conversion processes of vehicle engine under transient and steady-state conditions
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DOI：
10.1016/j.enconman.2016.11.038
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发表时间：
2017-01
影响因子：
10.4
通讯作者：
Zhengxin Xu;Fu Jianqin;Jing-ping Liu;Zhipeng Yuan;Jun Shu;Ligang Tan
中科院分区：
文献类型：
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作者：
Zhengxin Xu;Fu Jianqin;Jing-ping Liu;Zhipeng Yuan;Jun Shu;Ligang Tan
为了提高内燃机的实际性能，研究了内燃机缸内燃烧和热转换过程的暂态行为，提出了一种优化方法。以一台先进的增压汽油直喷(TGDI)发动机为研究对象，进行了发动机稳态台架试验、恒速负荷台架试验和整车道路试验。在此基础上，将车用发动机在负载阶跃和车辆行驶工况下的缸内燃烧和热功转换过程与稳态结果进行了比较。通过这种方法，展示了内燃机暂态性能与其稳态值的偏差，并揭示了它们的影响。研究结果表明，内燃机性能，特别是点火提前角在负载阶跃和稳态条件下具有令人满意的一致性。然而，在车辆行驶条件下，运行和控制参数严重偏离稳态值，波动很大，例如，在急剧减速条件下，点火提前角大大延迟。当IMEP低于4bar时，点火提前角严重偏离稳态值，导致燃烧特性参数波动较大，最终导致热功转换效率下降。此外，过量空气系数的波动也是内燃机暂态性能不稳定的主要原因之一。准确控制低负荷点火正时，减小过量空气系数的波动，是改善车辆行驶条件下内燃机性能的有效途径。
To improve the actual performance of internal combustion engine (ICE), the transient behaviors of in-cylinder combustion and heat-work conversion processes of ICE were investigated and an optimization method was proposed. Based on an advanced turbocharged gasoline direct injection (TGDI) engine, the steady-state bench test, load-step test at constant-speed and vehicle road test were carried out. On this basis, the in-cylinder combustion and heat-work conversion processes of vehicle engine under load-step and vehicle driving conditions were compared with the steady-state results. By this means, the deviations of ICE transient performance from their steady-state values were demonstrated and also their impacts were revealed. The research results show that there is a satisfactory consistency of ICE performance especially the ignition advance angle under load-step and steady-state conditions. However, under vehicle driving conditions, the operating and control parameters gravely deviate from the steady-state values with large fluctuations, e.g., ignition advance angle is retarded largely under the sharp deceleration conditions. When the IMEP is below 4 bar, the ignition advance angle seriously deviates from the steady-state values, which results in large fluctuation of combustion characteristic parameters and finally leads to the decrease of heat-work conversion efficiency. Moreover, the fluctuation of excess air coefficient is one of the main reasons for the instability of ICE transient performance. To accurately control the ignition timing under low load and decrease the fluctuation of excess air coefficient is an effective way to improve the ICE performance under vehicle driving conditions.