节温器对发动机热系统动态性能的影响

节温器非线性动态特性与发动机热系统延迟效应相互作用,使系统动态特性复杂。在建立节温器、散热器及发动机等部件集总参数模型的基础上,利用质量守恒、动量守恒和能量守恒等基本控制方程,建立了描述热系统复杂动力学过程的数学模型,发展了相应算法,并利用该方法对发动机冷起动过程的热系统动态特性进行了仿真计算和对比分析。研究结果表明,节温器的布置方式和时间延迟、温度偏移等热特性对发动机热系统动态性能影响显著。

Influences of thermostat on engine thermal system transient performance

The interplay between thermostat nonlinear dynamic characteristics and engine thermal system hysteresis complicates system transient phenomena. A mathematical model to predict the complicated operation process of the engine thermal system was developed. On the basis of the mass, momentum and energy governing equations for the whole thermal-fluid networks, the thermostat, radiator, engine and other components were described by lumped parameters. The model was solved numerically and the real-time simulation was achieved to analyze the thermal system transient phenomena in the engine warm-up process. The investigation results indicate that the allocations and temperature-response characteristics of the thermostat, including hysteresis offset, time resistance and etc, have great influences on the engine thermal system transient performance.