基于高速开关阀的换挡离合器油压控制研究

以变速器换挡离合器油压控制系统为研究对象,提出基于高速开关阀的换挡离合器油压控制方法,分析高速开关阀的工作原理,建立以高速开关阀为液压控制主阀的换挡离合器油压控制系统,并且阐述了系统的工作过程。在此基础上,基于AMESim分别建立了包含电磁式高速开关二位三通阀和二位二通阀的换挡离合器油压控制系统模型,通过对两个系统的油压控制性能进行仿真对比,表明选用二位三通阀作为主阀的油压控制系统性能更为优越。     

干式双离合自动变速器压力控制系统研究

对干式双离合自动变速器液压系统组成及其工作原理进行深入剖析,并利用EASY5软件对蓄能器压力控制系统及离合器压力控制系统进行仿真研究,从而明确各分系统的工作原理与工作特性;通过台架实验验证了建模仿真的正确性,进一步研究了压力控制系统的静态响应特性,为下一步控制策略的制定及控制系统的开发提供依据。     

基于高速开关阀的湿式离合器缓冲控制系统研究

湿式离合器是大功率液力机械传动装置重要的传动部件，其工作状态直接影响设备的安全可靠运作。为了提高湿式离合器工作效率，通过分析离合器的工作原理，基于电磁式高速开关阀设计一种用于湿式摩擦离合器的液压控制系统，构建液压系统模型，通过 MATLAB/Simulink仿真求解该液压系统的压力输出信号。计算结果显示：该液压系统可以用于控制湿式离合器的接合，能够为湿式离合器提供稳定的接合油压缓冲信号。     

一种用于湿式摩擦离合器的液压控制系统的设计

为了保证湿式摩擦离合器工作时所需压力信号的准确性和平稳性,设计一种用于湿式摩擦离合器的液压控制系统。对湿式摩擦离合器的模型进行分析,获取湿式摩擦离合器的传递扭矩;利用液压泵、系统压力阀以及液压比例减压阀等设计了液压控制系统;分析该液压控制系统的工作过程,求取了离合器压力阀所产生压力的常微分方程,在此基础上计算了离合器所需压力的微分方程,并在MATLAB/Simulink环境下进行了仿真实验。仿真结果显示：所设计的液压控制系统对线轴位移信号及压力信号的控制准确性及平稳性都较好,所控制的线轴位移信号较标定线轴位移信号的偏差不超过6667%,所控制的压力信号较标定压力信号的偏差不超过9524%。说明所设计的液压控制系统能够为湿式摩擦离合器提供准确且稳定的工作压力信号。     

高能离合器螺旋压力机打击力控制过程分析

本文分析了高能离合器螺旋压力机惯性控制系统的工作原理及控制特性,导出了打击力与主螺杆角减速度之间及惯性控制机构运动规律与主螺杆角减速度之间的关系式,从而建立了快速脱开阀调定油压与离合器脱开时的锻击力、终锻力之间的关系,为压力机惯性控制系统参数设计和控制技术提供了必要的理论依据。     

双离合器控制电磁阀特性研究

比例电磁阀作为离合器液压缸油压控制的关键元件,对DCT性能的影响深刻。以DCT离合器控制的比例电磁阀为研究对象,在分析其结构与工作原理的基础上建立电磁阀电场、磁场、液压和机械4个物理场耦合模型,并以ANSYS/Maxwell对电磁铁系统进行动态特性分析。进一步结合电磁力特性数据建立电磁阀控制离合器AMESim模型。台架试验结果与仿真结果有较高吻合度,验证了数学模型的正确性及仿真方法的可靠性,为进一步优化电磁阀结构及其压力控制方法提供了理论支撑。     

双离合器自动变速器无冲击换档过程的实现

介绍了双离合器的结构及换档工作原理,建立了双离合器换档模型.在此基础上推导出了双离合器自动变速器实现无冲击换档时,各控制参数变化应满足的相互关系,并对其进行了仿真验证,为双离合器控制器的设计提供了理论依据.     

基于AMESim的液粘调速离合器PID控制特性研究(英文)

为了准确模拟液粘调速离合器电液比例闭环控制特性,使系统能达到稳定转速的目的,基于AMESim仿真软件构建液粘调速离合器PID闭环控制系统仿真模型。采用Ziegler-Nichols整定法确定了PID参数,研究了液粘调速离合器闭环控制系统输出响应特性,分析了PID参数对输出特性的影响。结果表明,该方法能准确地模拟液粘调速离合器PID闭环控制输出响应特性,PID参数对系统输出响应特性和转速稳定性均有较大的影响。通过PID闭环控制系统,液粘调速离合器可以达到恒转速控制,得到的仿真结果为控制器的设计提供了参考依据。     

自动变速器换挡电磁阀设计及仿真研究

在分析自动变速器先导式换挡电磁阀工作特性、工作原理的基础上,对电磁阀的具体结构参数进行了设计计算,并建立了换挡电磁阀的AMESim仿真模型。仿真结果表明,根据所设计的换挡电磁阀得到的离合器压力变化曲线符合离合器接合过程压力变化规律,研究结果为自动变速器换挡控制奠定了基础。     

重型AT换挡控制油压变化及稳定性的研究

为了改善和保证重型液力自动变速器的换挡品质,在分析重型液力自动变速器换挡液压控制系统工作原理的基础上,建立换挡回路油压控制数学模型,基于AMESim搭建仿真模型,并从占空比、换挡阀弹簧预紧力和阀口开口量等因素对换挡时离合器油压变化及稳定性展开研究。仿真结果显示:换挡时间约为1.6 s,在t=1～1.6 s期间,这些因素对离合器油压影响较大,而后离合器的油压仅受主油压调节而发生变化,t=3.2 s达到稳定压力,满足实际工作要求;同时仿真结果与理论分析相一致,验证了模型的正确性和有效性,为液力自动变速器换挡控制和装配提供一定的参考。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。