高速柴油机气门失效分析与改进

通过对高速柴油机,特别是重载柴油机气门常见的失效形式进行分析,探讨了引起气门实效的各种因素,从气门设计、材料选择、制造和使用的角度提出了改进措施,对柴油机气门设计和维护保养有一定的借鉴作用。     

增压柴油机的气门与气门座圈的改进与试验验证

对柴油机进行增压后在可靠性试验过程中出现了进气门、进气门座快速磨损的原因进行了分析,提出了改进措施,并对不同材料的气门、气门座进行了优化选配试验,根据试验结果选择出满足使用要求的气门与气门座。     

增压柴油机的气门与气门座圈的改进与试验验证

对柴油机进行增压后在可靠性试验过程中出现了进气门、进气门座快速磨损的原因进行了分析,提出了改进措施,并对不同材料的气门、气门座进行了优化选配试验,根据试验结果选择出满足使用要求的气门与气门座。     

F3000柴油机的气门导杆窜油研究

玉柴F3000型柴油机气门导杆窜油主要是因为气门导管的结构和油封的性能所致,笔者提出了利用更换气门油封的方法来减少F3000柴油机的窜油问题,通过对比实验表明,使用更合适的气门油封是解决F3000柴油机气门杆窜油的可行的方案之一.     

浅谈柴油机气门间隙调整

针对气门间隙对柴油机工作和安全的重要意义,阐述了气门间隙不当对柴油机产生的危害和气门间隙调整时机,并总结归纳了两类行之有效的气门间隙检查与调整方法,最后对柴油机使用维护提出了几点建议。     

柴油机气门座材料选择和镶嵌方法

柴油机气门座的损坏与材料及镶嵌方法有极大的关系，文中从柴油机工作对气门座的要求开始．介绍了气门座的材料选择和正确的镶嵌方法。     

柴油机气门结构设计

通过对柴油机气门结构部位分析,简述了气门结构设计中应注意的问题.     

柴油机气门结构设计

通过对柴油机气门结构部位分析，阐述了气门结构设计中应注意的问题。     

NiCr20TiAl材料在大功率、高排温柴油机气门上的应用

为满足某型号柴油机气门在高排温下工作的可靠性以及气门的耐磨性要求,本文从材料选配角度出发,对多种不同材料的气门进行对比分析以及试验验证,选出比较适合大功率、高排温柴油机的气门材料。     

NiCr20TiAI材料在大功率、高排温柴油机气门上的应用

为满足某型号柴油机气门在高排温下工作的可靠性以及气门的耐磨性要求,本文从材料选配角度出发,对多种不同材料的气门进行对比分析以及试验验证,选出比较适合大功率、高排温柴油机的气门材料.     

循环流化床锅炉U型返料阀的冷态试验研究

返料阀是循环流化床锅炉的关键部件之一 ,其性能的优劣直接影响锅炉的正常运行及其继续向大型化发展。U型返料阀 (以下简称U阀 )虽然在循环流化床锅炉中应用最广泛 ,但是 ,各生产厂的U阀结构形式不尽相同 ,相应的返料特性也不尽相同。结构设计不合理 ,返料阀在运行中就会出现堵灰和结渣、返料量不稳定和不返料的现象。那么 ,什么样的U阀结构是合理的呢 ?为此 ,我们在实验室对U阀进行了冷态试验研究 ,并查阅有关文献、与其他学者的研究结果进行了比较 ,得出的结论供设计U阀时借鉴。     

JZ-7型制动机双端操纵一个中继阀的制动系统

介绍在DF7C、DF7G型机车上保持JZ-7型制动机性能不变、机车操纵方式不变的情况下,由原来的双端操纵使用2个中继阀改为双端操纵使用1个中继阀方案的制动系统工作原理,并把相应各阀移到司机室外,方便机车的使用、检修和制造。     

平衡阀在供热系统中的应用

在阐述平衡阀发展及工作原理的基础上,给出各种常用平衡阀的选择方法,探讨平衡阀的应用场所及安装注意问题。简要介绍电动动态平衡阀的应用系统调节过程,并推导调节传递函数,对平衡阀在工程中经济、科学选用具有指导意义。     

国外高压共轨喷油器电磁阀结构分析

从结构和材料两方面分析了博世公司和电装公司的共轨喷油器电磁阀.分析表明:两家公司的技术路线完全不同.博世公司采用球阀密封,衔铁和衔铁杆分离;铁芯和衔铁材料为合金结构钢;衔铁采用渗碳淬火处理.电装公司采用平面阀密封,预紧力较小;铁芯材料为粉末冶金;衔铁工艺复杂,吸合面为软磁性能较好的粉末冶金材料,撞击面为硬度较高的高速钢...     

一种应用于三联产系统的新型的物料回送阀的试验

文中介绍了一种新型的回送阀的试验运行的特性,并结合其它回料阀的特点,讨论本实验用回料阀的所特有的结构特点,分析了试验得出的输送特性曲线和气固比曲线,为进一步实现三联产的工业应用奠定了良好的基础。     

Experimental and numerical analysis of spring stiffness on flow and valve core movement in pilot control globe valve

Valves are widely used for fluid flow control, not only for conventional fluid like water, gas and oil, but also for hydrogen under high pressure and so forth. Under these new conditions, the response time and energy consumption of valves are closely related to the whole performance of the piping system. Pilot-control globe valve (PCGV) is a novel quick response valve, which can utilize the pressure difference before and after the valve core to control the open/close states of the main valve. In this paper, the effects of spring stiffness inside PCGV on the flow and the valve core movement are carried out, respectively. To begin with, the experimental setup is introduces and the 3D numerical model is established. The simulation is carried out in software FLUENT with RNG k-ε turbulence model, User Defined Function method and dynamic mesh regeneration methods under transmit state. Then, a comparison of steady valve core displacements between experiment and simulation is carried out. After that, the effects of spring stiffness on flow characteristics, valve core movement and response times during opening and closing periods are presented. Finally, a spring chosen correction equation is proposed. This work can benefit the further design work of PCGVs or similar valves with springs, and it can be also referred by someone dealing with novel control valves design or flow control issues.     

The effects of improper refrigerant charge on the performance of a heat pump with an electronic expansion valve and capillary tube

For inverter heat pumps and multi-type heat pumps, conventional expansion devices such as capillary tubes, short tube orifices, and thermostatic expansion valves (TXVs) are being gradually replaced with electronic expansion valves (EEVs) because of the increasing focus on comfort and energy conservation. In this study, the effects of off-design refrigerant charge on the performance of a water-to-water heat pump are investigated by varying refrigerant charge amount from −20% to +20% of full charge in a steady state, cooling mode operation with expansion devices of capillary tube and EEV. The characteristics of the heat pump with an EEV are compared with those with a capillary tube. The capillary tube system is more sensitive to off-design charge as compared with the EEV system. Cooling capacity and COP of the EEV system show little dependence on refrigerant charge, while those are strongly dependent on outdoor conditions. In general, for a wide range of operating conditions the EEV system shows much higher performance as compared with the capillary tube system. The performance of the EEV system can be optimized by adjusting the EEV opening to maintain a constant superheat at all test conditions.     

16V280ZJ型柴油机进排气门早期裂纹原因分析与解决措施

根据16V280ZJ型柴油机近两年在机务段发生的气门裂纹、掉块、穿孔的情况,通过对进排气门密封面的应力分析及气门本身的理化分析,阐明了进排气门发生裂纹的机理,并提出了解决进排气门裂纹问题的途径。     

焊接波纹管式温控阀的设计和试验研究

针对风电机组润滑油冷却系统中传统橡胶囊式温控阀使用寿命短、综合运营成本居高不下等问题,设计、制造了焊接波纹管式温控阀,实验研究了其动作特性并进行了实际应用。风机齿轮箱润滑油冷却系统中,温控阀的调节行程长、稳定性要求高、使用环境恶劣,焊接波纹管结构的引入,既满足了温控阀的实际功能需求,又克服了传统囊式温控阀使用寿命低、性能不稳定等缺点。通过试验,合理设计了温控阀的调节弹簧参数,将其与焊接波纹管配合使用,满足了温控阀的复位调节需求。通过填充蜂窝铝材料强化了储蜡腔的内部导热能力,有效提高了焊接波纹管式温控阀的响应速度。实际挂机试验表明,焊接波纹管式温控阀能有效代替传统囊式温控阀,有效降低风机综合运营成本,可作为风机齿轮箱润滑油冷却系统技术改造方案推广使用。     

Impact of variable valve timing on power,emissions and backfire of a bi-fuel hydrogen/gasoline engine

Hydrogen-fueled internal combustion engines are a possible solution to make transportation more ecological. Apart from difficulties in production and storage of hydrogen, there are three major bottlenecks in the operation of hydrogen-powered engines: reaching a high power output, reducing NO_x emissions at high loads and avoiding backfire. This paper presents an experimental study of the influence of continuously variable valve timing of the intake valves on these bottlenecks. Measurements were performed on a four-cylinder engine that can run on gasoline as well as on hydrogen. The measurements on hydrogen are compared to those on gasoline. For hydrogen, the effects of the cam phasing were investigated at wide open throttle, where load is controlled by the quality of the mixture (equivalence ratio) as well as in throttled mode, where load is defined by the quantity of mixture.