高效低污染非道路卧式柴油机关键技术研究

【作者】 雷基林；

【导师】 申立中；

【作者基本信息】 昆明理工大学 ， 机械设计及理论， 2011， 博士

【摘要】 非道路柴油机是我国农业机械、工程机械、林业机械、内河机动船、发电机组以及水泵等的主要配套动力,我国现有非道路卧式柴油机因售价低以及冷却方式和结构的限制,技术发展严重滞后,主要表现在：体积大、比质量大、升功率低,可靠性低、寿命短,冷却效果差,燃油经济性差、噪声和排放污染物严重。针对现有非道路卧式柴油机存在的技术问题,提出了开发高效低污染非道路卧式柴油机需解决的关键技术方案,开展了以下研究工作。(1)针对进气系统,研究了螺旋进气道结构及其流动特性的影响关系针对柴油机螺旋进气道复杂的自由曲面特征,通过建立螺旋段表面空间三维曲线方程组数学模型和启用曲线关联特性,研究了一种柴油机螺旋进气道正向设计方法。结合气道稳流实验,建立了气道流动仿真模型,研究了螺旋进气道直流段和螺旋段几何结构参数、进气门位置对气道和缸内气体流动特性的影响关系,分析了进气道的关键结构参数和敏感部位。(2)针对冷却系统,研究了卧式柴油机冷却水套结构及其流动特性针对新型高效低污染非道路卧式柴油机的技术要求,选择了强制冷却闭式循环系统,设计了冷却水套结构方案。在不同工况下试验测试了水套内冷却水流量、温度和压力,建立了冷却水流动的数值模拟仿真模型,分析了水套内冷却水流动性能,研究了不同结构参数对冷却水流动和换热的影响关系,优化了原方案冷却水套结构和水泵流量。(3)研究了活塞组动力学特性及其影响因素针对卧式柴油机活塞组件动力学特性,试验研究活塞、缸套热负荷作用下的温度场分布,建立了活塞组件动力学仿真模型。采用正交分析方法,研究了活塞和活塞环结构参数对活塞组二阶运动、机油耗以及漏气量等活塞组动力学特性的影响关系。(4)高效低污染非道路卧式柴油机的设计通过对燃烧系统的设计与优化匹配试验、冷却系统、润滑系统、活塞组件、配气机构等部件的设计与分析以及总体布置,设计了一款新型高效低污染非道路用卧式两缸柴油机,其结构特点及性能指标如下：(1)结构紧凑、重量轻。自然吸气柴油机产品总质量221kg,比质量6.05kg/kW;废气涡轮增压功率强化后2D25ZL总质量227kg,比质量4.54kg/kW。(2)燃油经济性好。自然吸气柴油机外特性最低燃油消耗达到224g/(kW·h),标定功率工况点有效燃油消耗率为234g/(kW·h);增压中冷柴油机外特性最低燃油消耗达到221g/(kW·h),标定功率工况点有效燃油消耗率为246g/(kW·h)。发动机最经济有效燃油消耗区宽广,动力适配范围宽。(3)润滑油消耗低。自然吸气柴油机标定功率工况下平均机油耗0.299 g/(kW·h),平均机油燃油消耗比为0.127%；增压中冷柴油机标定功率工况下平均机油耗0.293 g/(kW·h),平均机油燃油消耗比为0.119%。(4)排气污染物低,可靠性高。自然吸气柴油机满足非道路国Ⅱ排放限值的要求,并通过了1000小时可靠性试验检验。更多还原

【Abstract】 The off-road diesel engines are mainly power, which are widely uesed as agricultural machines, engineering machines, forestry machines, marine ships, generators and pumps in our country. Because of the low price and the limit of cooling method and structures, the technologic development of horizontal off-road diesel engine lagged seriously in our country. The chief characteristics were the large volume, the heavy mass density, the low power per liter and the reliability, the short life, the bad cooling effect and fuel economy, and the serious noise and emission pollutant. Aiming at the technical matters of the existing horizontal off-road diesel engine, the key technical proposals for designing the high efficiency and low pollute off-road diesel engines were put forward, and the researching work were investigated as follows.(1) Researching the influent relationship of the structure of helical intake port to flow characteristics of the intake portAiming at the complex free curved surface characteristic of helical intake port, a top-down design way of helical intake port for diesel engine was put forward and the complicated three-dimensional model and the numerical simulation model of helical intake port for diesel engine were set up by establishing three-dimensional curve mathematical model of the helical section surface space and using curve association characteristic. The simulation model of intake port was built based on the steady flow experiments. The effects of the geometry parameters of helical intake port straight section and helical section and the intake valve position on the intake port and the gas flow characteristic in cylinder were researched and the key geometry parameters and the sensitive part of the intake port were analyzed.(2) Researching the structure of cooling jacket and flow characteristics of the cooling systemIn order to fulfill the technical requirements of a high-efficiency low-emissions off-road horizontal diesel engine, a unique design is proposed for the cooling water jacket structure with a forced-cooling closed-loop cooling system. The cooling water flow rate, temperature, and pressure at the inlet and several other critical locations of the cooling water jacket were measured and analyzed at different engine operating conditions for the water jacket design. A numerical simulation model of the coolant flow and the cooling system was built and used to analyze the thermal/fluid characteristics of the coolant flow in the water jacket. The impact of different structural and packaging design parameters on the coolant flow and heat transfer was investigated. The cooling water jacket structure and the water pump flow rate were optimized.(3) Researching the dynamics characteristics and influent factors of piston assemblyBased on the dynamics characteristics of piston assembly, the temperature distribution of the piston and cylinder liner was researched on the thermal load condition and the dynamic model of piston assembly was established. The influent relation of piston and piston rings structural parameters to the secondary motion of the piston assembly, the influent relation of oil consumption and gas leak to dynamics characteristic of piston assembly were researched based on the orthogonal design method.(4) Designing the high efficiency and low pollute horizontal off-road diesel engineA new type of high efficiency low pollute horizontal off-road diesel engine was designed based on the design and optimization of matching test of the combustion system, the innovative design and analysis of engine body, cooling system, lubrication system, piston assembly, valve trains and overall layout of other components. The structural characteristics and performance indices of this new engine are as follows:(1) The diesel engine was compact and light. The total mass was 221kg, and the specific mass was 6.05kg/kW with the state of naturally aspirated. The total mass was 227kg, and the specific mass was 4.54kg/kW after being strengthened by the exhaust turbocharger.(2) The fuel consumption was economical. At the full load characteristic working state of naturally aspirated, the lowest fuel consumption was 224g/(kW·h) and the effective fuel consumption was 234g/(kW·h) at the point of rated power. At the working state of turbocharged and intercooled, the lowest fuel consumption was 221g/(kW·h) and the effective fuel consumption was 246g/(kW-h) at the point of rated power. This showed that the effective fuel consumption area and the power adaptive range were wide to this diesel engine.(3) The lubricating oil consumption was lower. At the full load characteristic working state of naturally aspirated, the average oil consumption was 0.299 g/(kW·h) and the average fuel consumption ratio was 0.127%. At the working state of turbocharged and intercooled, the average oil consumption was 0.293 g/(kW·h) and the average fuel consumption ratio was 0.119%.(4) The exhaust emissions were low and worked reliably. The emissions were in accordance with the National stageⅡemission limits at the full load characteristic working state of naturally aspirated. And the reliability experiment of 1000 hours met the National Standard at the extra characteristics working state of naturally aspirated.更多还原