液压挖掘机发动机冷却系统性能及工作参数匹配研究

【作者】 李琳；

【导师】 陈欠根；

【作者基本信息】 中南大学 ， 机械设计及理论， 2009， 硕士

【摘要】 液压挖掘机工作环境十分恶劣,尤其对于小型液压挖掘机,由于其冷却风道空间有限,很容易造成发动机冷却水温过高的现象,从而导致挖掘机工作效率以及使用寿命的降低。目前挖掘机厂家对于发动机冷却系统的设计主要通过经验和反复试验来完成,这一方面延长了设计的周期,同时也增加了试验的强度。本文针对液压挖掘机发动机冷却系统设计过程中存在的共性问题,结合国家863课题及企业科研攻关项目从理论上对发动机冷却系统性能进行了系统的研究,并利用MATLAB/GUI工具箱,编写了发动机冷却系统分析软件,为设计人员对冷却系统进行改进提供了理论指导。论文将对以下几个方面展开研究:首先,综述国内外发动机冷却系统研究及发展现状及趋势。介绍目前常用的散热器型式,揭示间壁式散热器的传热机理。其次,建立管带式散热器散热特性数学模型,分析散热器传热系数、冷却水温度、散热量、风阻、水阻以及功耗等性能参数与散热器尺寸及流体流速之间的关系,并通过SWE50型液压挖掘机冷却系统相关实验,对该模型进行验证。同时,运用MATLAB/GUI工具箱,编写发动机冷却系统分析软件,用户通过GUI界面设置冷却系统对应的尺寸参数及工况参数,经过分析软件进行计算,得到相应的性能曲线及性能参数值。再次,对发动机冷却系统风道进行分割、简化,在目前常见的圆孔型出风口流道方案的基础上提出一种百叶窗型出风口流道优化方案,利用FLUENT数值模拟仿真软件对两种方案流场进行分析、对比。同时,通过对细化后的圆孔型出风口流道网格模型进行数值计算,得到该方案风速-风阻变化规律。最后,针对SWE50型液压挖掘机发动机冷却系统,建立冷却系统工作参数优化匹配数学模型,利用MATLAB遗传算法工具箱对散热器部分尺寸参数、水流量以及风速进行优化匹配。更多还原

【Abstract】 Engine cooling system is the key of guaranteeing the hydraulic excavator’s normal operation and highly active working. This paper aimed at some common problems existing in the design process of hydraulic excavator’s cooling system and researched the combination property of engine cooling system systematically, combined with the national program 863 and enterprise’s key scientific research program. In this paper, MATLAB/GUI toolbox has been used to compile the engine cooling system’s analysis software. It has provided theoretical guidance for the designers to improve the cooling system. This paper’s main work is as follows:Firstly, the research development status and tendency of national and international engine cooling systems have been summarized. Radiator type for common use has been introduced, and plate-fin radiator’s heat-transfer mechanism has been revealed.Secondly, the numerical mode of louvered fin-and-tube radiator’s thermal characteristics has been established. The relationship between some performance parameters, such as radiator’s heat transfer coefficients, temperature of cooling water, heat dissipation, windage resistance, water resistance, power dissipation and the size of radiator and velocity of fluid has been analyzed. Some experiments based on the SWE50 hydraulic excavator’s cooling system have been used to prove the mode. Meanwhile, the engine cooling system’s analysis software has been compiled by using the MATLAB/GUI toolbox, and then users could get relevant performance curves and performance parameters by using GUI interface to input cooling system’s corresponding size-parameter and working parameter and do some calculations though analysis software.Thirdly, engine cooling system’s wind channel has been cut up and simplified, an optimized scheme of shutter type wind channel has been put forward, which is based on the common scheme of round hole wind channel. The two types of schemes have been analyzed by using FLUENT numerical simulation software. Meanwhile we got the changing discipline between wind speed and wind resistance by calculate the round hole air outlet channel’s grid mode. At last, the cooling system’s optimize and match numerical mode has been built based on the SWE50 hydraulic excavator’s cooling system. The radiator’s size parameter, water discharge parameter and wind speed has been matched by using the MATLAB genetic algorithm toolbox.更多还原