电动废气再循环阀驱动力衰减

针对有刷电机驱动电控废气再循环（exhaust gas recirculation,EGR）阀驱动力衰减的现象,对EGR阀开展常温、高温耐久测试及整车耐久测试。测试结果表明：在不同测试条件下EGR阀驱动力都会衰减;环境温度越高,EGR阀驱动力衰减程度越大;EGR阀驱动力在5万个循环以内或整车运行1万km以内的衰减速度较快;衰减的主要原因是有刷直流电机工作转矩衰减。     

一种电子EGR阀安装孔的优化设计

通过失效原因分析、CAE分析、加工工艺分析等方面,对EGR阀安装孔进行了优化设计,并通过试验验证,成功解决了EGR阀安装孔漏气及EGR阀拆卸断裂的问题。     

某欧Ⅳ柴油发动机EGR冷却系统优化设计

本文通过对某欧Ⅳ柴油发动机EGR冷却系统的优化设计,解决了原型机EGR冷却系统设计不合理,使得EGR阀入口废气温度过高导致EGR阀烧蚀失效的问题。同时通过耐久试验验证,确定了流经EGR阀废气温度的合适范围。对EGR冷却系统的设计开发都具有指导意义。     

TRIZ创新方法在EGR阀布置设计中的应用

基于TRIZ创新方法,分析废气再循环(EGR)阀布置中面临的矛盾和问题,并进行概念设计。在EGR布置概念设计完成后,进行概念设计验证,确认EGR阀布置设计的开发结果。     

一种实用节能减排型步进式电机控制EGR阀

针对电子控制式EGR存在结构复杂,能耗高以及可靠性不高等缺点,将步进电机引入对EGR阀的控制中,设计了包括步进式电机、EGR控制阀、各传感器和电子控制器ECU等部件在内的实用节能减排型步进式电机控制EGR阀。结果表明,实用节能减排型步进式电机控制EGR阀不但具有结构简单,能耗小以及可靠性高的特征,而且还能有效地提高燃油的利用率,减少尾气中氮氧化合物的含量。     

EGR流通能力及可靠性考核试验装置的开发

在涡轮增压器压气机特性台架基础上,设计了一套以三通阀为主体的EGR流通能力及可靠性考核试验装置,该套装置的开发圆满完成了EGR阀新品流通及高温可靠性试验,验证了该套装置设计的合理性。     

某柴油机EGR阀结焦问题的分析

采用冷却EGR,在降低NO2排放的同时,微粒(PM)排放及燃油经济性没有明显恶化,从而使其已成为目前先进柴油机主流技术之一。尤其是使用电控EGR阀能够更精确地控制EGR量,使得发动机能够在各种工况下发挥出最佳效果,但由于电控EGR阀要求的边界使用条件较为严格,也更容易出现问题。我们以某柴油机出现的EGR阀结焦问题为案例,来探讨EGR阀结焦问题的解决方法。     

EGR系统在SNH495A型柴油机中的标定试验

进行EGR系统在SNH495A型柴油机上的标定实验研究。采用真空度控制EGR阀开度,实现废气再循环系统的调节。利用柴油机台架试验完成EGR阀真空度的匹配标定。经过多次试验,找到不同功率下的EGR阀最佳开度,完成EGR系统的标定。     

内燃机的废气再循环技术

介绍内燃机废气再循环(EGR)的工作原理、废气再循环量的评价指标EGR率、汽油机的EGR系统控制和柴油机EGR的效果及控制，以及采用EGR对柴油机工作过程和性能的影响。     

基于不同EGR系统的发动机性能仿真研究

对不同排气再循环(exhaust gas recirculation,EGR)系统对发动机性能的影响进行仿真分析。结果表明:单路EGR系统缩小涡轮尺寸可以产生较高EGR率,但是油耗较高;单向阀在涡轮尺寸较大时具有较好地提高EGR率的效果;与单EGR冷却器相比,两路EGR系统双EGR冷却器具有提高EGR率的潜力;两路EGR系统+单向阀泵气损失小,EGR效率高且油耗低。     

风电叶片疲劳加载试验电磁激振特性研究

提出一种基于电磁力驱动的风电叶片疲劳加载新方法。为进一步得到电磁机构参数对激振力特性的影响规律,首先,以螺线管式电磁铁为加载装置,采用解析法构建电磁疲劳加载系统数学模型;其次,设计多阶段电磁激振力并通过能量守恒定律得到电磁力与叶片振幅和频率的关系;最后,利用ANSYS Maxwell软件建立磁场仿真模型,验证电磁激振力设计的合理性,并分析电磁铁结构参数对加载力及速度的影响,得出在给定的叶片规格下满足测试要求的电磁机构的线圈匝数、形状参数、铁心长度、铁心外径的优选范围,可为后续电磁式疲劳加载试验台的开发奠定理论基础。     

Hip-mounted electromagnetic generator to harvest energy from human motion

A type of electromagnetic hip-mounted generator (EHG) is proposed to harvest energy from human hip motion to generate electricity. Based on the law of electromagnetic induction, the EHG generator can convert the kinetic power of the thigh swing into electrical energy during walking or running. To demonstrate the feasibility of the present method, a prototype of the EHG has been designed and fabricated. A theoretical analysis has been conducted to interpret the working behavior of this prototype. In addition, the performance of the system has been experimentally tested through a rotary motor and human body motion. When driven by the rotary motor at a rotation speed of 100 r/min, the open-circuit voltage of this prototype is 2.5 V. Further, a maximum open-circuit voltage of approximately 1 V and a maximum output power of 284 μW could be produced respectively when walking with an EHG at a speed of 1.47 m/s. This handy renewable energy technology is promising as a pervasive electricity generation system for a group of wearable or implanted sensors, actuators and mobile electronics.     

高速开关电磁阀的研究及测试

高速开关电磁阀在电磁控制系统中是一种结构简单、易于实现计算机控制的关键控制元件，它的性能指标对整个电液系统有很大的影响。本文设计了一种新型的双线圈结构的高速开关阀，并对其性能进行了测试和研究，给出电磁阀设计过程中需注意的几点建议，最后，给出了电磁阀在电控系统中的应用方法。     

煤粉气流在交变电磁场与高温壁面协同作用下着火过程的机理研究

详细研究了在感应式无油直接点火燃烧器点火室中 ,煤粉气流在着火过程中的机理。研究表明 :煤粉气流在感应式加热无油直接点火器中的着火过程 ,是交变电磁场与高温壁面加热协同作用的结果。交变电磁场是针对煤粉气流在着火过程中有关特征发生变化 :煤粉颗粒的半导电性 ;挥发分及中间产物的极性、分子的电负性 ;大量存在的、特别是燃烧产物中的各种带电离子。煤粉气流在感应式加热无油直接点火器着火过程中所表现出的特征 ,表明它是一种很有发展前景的点火方式     

Effect of static magnetic field on a thermal conductivity measurement of a molten droplet using an electromagnetic levitation technique

Recently, a novel method of measuring the thermophysical properties, particularly thermal conductivity, of high-temperature molten materials using the electromagnetic levitation technique has been developed by Kobatake et al. [H. Kobatake, H. Fukuyama, I. Minato, T. Tsukada, S. Awaji, Noncontact measurement of thermal conductivity of liquid silicon in a static magnetic field, Appl. Phys. Lett. 90 (2007) 094102]; this method is based on a periodic laser-heating method, and entails the superimposing of a static magnetic field to suppress convection in an electromagnetically levitated droplet. In this work, to confirm the fact that a static magnetic field really suppresses convection in a molten silicon droplet in an electromagnetic levitator, numerical simulations of convection in the droplet and periodic laser heating in the presence of convection have been carried out. Here, the convections driven by buoyancy force, thermocapillary force due to the temperature dependence of the surface tension on the melt surface, and electromagnetic force in the droplet were considered. As a result, it was found that applying a static magnetic field of 4 T can suppress convection in a molten silicon droplet enough to measure the real thermal conductivity of molten silicon.     

电磁悬浮熔炼离心铸造设备的研制

电磁悬浮熔炼离心铸造（ＥＬＣＣ）技术是大幅度降低太阳电池硅片成本的一条新途径。报道了该设备的研制及总体设计方案，介绍了炉体、电源系统、机械系统、辅助系统及其相互配合。该设备已应用于ＥＬＣＣ技术及其相关工艺的研究。     

Loss evaluation and design optimisation for direct driven permanent magnet synchronous generators for wind power

When designing a generator for a wind turbine it is important to adapt the generator to the source, i.e. the wind conditions at the specific site. Furthermore, the variable speed operation of the generator needs to be considered. In this paper, electromagnetic losses in direct driven permanent magnet synchronous generators are evaluated through simulations. Six different generators are compared to each other. The simulations are performed by using an electromagnetic model, solved in a finite element environment and a control model developed in MATLAB. It is shown that when designing a generator it is important to consider the statistical wind distribution, control system, and aerodynamic efficiency in order to evaluate the performance properly. In this paper, generators with high overload capability are studied since they are of interest for this specific application. It is shown that a generator optimised for a minimum of losses will have a high overload capability.     

Direct power control of wind‐turbine‐driven DFIG during transient grid voltage unbalance

In this paper, a direct power control (DPC) of a wind‐turbine‐driven doubly fed induction generators (DFIGs) under unbalanced network voltage conditions is studied. Variations of the stator output active, reactive and electromagnetic powers are fully deduced in the presence of negative sequence supply voltage. The rotor side converter is controlled on the basis of DPC to eliminate the electromagnetic torque oscillations at double supply frequency under unbalanced stator supply. The rotor voltage references estimation requires only simple calculations without any integral operation. The proposed control scheme removes rotor current regulators and the decomposition processing of positive and negative sequence rotor currents. The performance of the proposed and conventional DPC schemes is compared under the same operating conditions. Simulation results using Matlab/Simulink are carried out for a 1.5 MW DFIG wind generation system to show the validity of the proposed scheme during unbalanced voltage supply. Copyright © 2013 John Wiley & Sons, Ltd.     

Induction motors variable speed drives diagnosis through rotor resistance monitoring

Induction motor driven by vector control method makes high performance control of torque and speed possible. The decoupling of flux and electromagnetic torque obtained by field orientation depends on the precision and the accuracy of the estimated states. Rotor asymmetries lead to perturbations of air gap flux patterns in induction machines. These perturbations in flux components affect the electromagnetic torque, as well as stator currents and voltages. This paper first investigates the control of the induction motor using an extended Kalman filter (EKF) for a direct field-oriented control. It then studies the broken rotor bars (BRBs) fault by the monitoring the rotor resistance. The hypothesis on which the detection is based is that the apparent rotor resistance of the motor will increase when a rotor bar breaks. The rotor resistance is estimated and compared with its nominal value to detect BRBs fault. The EKF estimates the rotor flux, speed and rotor resistance on line by using only measurements of the stator voltages and currents. Simulation results show the effectiveness of the proposed method in the cases of load torque perturbation and speed reversion.     

Optimal parameters for pulsed gas tungsten arc welding in partially and fully penetrated weld pools

In the present paper, a numerical model of spot pulsed current GTA welding for partially and fully penetrated weld pools is presented. Heat transfer and fluid flow in the weld pool driven by the combination of electromagnetic force, buoyancy force, surface tension gradient and latent heat are included in our model. A new formulation of the electromagnetic problem is introduced to take into account eddy current in the weld pool. The shape of the free deformable surface under the action of pulsed arc force is also handled after the magneto-hydrodynamic calculation.The numerical model was applied to 304 stainless steel welding. We compare the influence of various pulsed welding parameters such as pulse frequency and current ratio on the weld quality. Experimental study is conducted to compare our numerical prediction with welding macrographies. It shows a good agreement of the model.