汽油机瞬时机油压力低故障分析

某汽油发动机转速从4 000 r/min以上突降至怠速时,瞬时机油压力报警器报警。针对该现象,对机油压力报警器、油路、转子机油泵性能、机油泵转子间隙及机油泵内转子与曲轴轴颈驱动面间隙进行检测和试验。逐一分析了各种原因,最终找出发动机瞬时机油压力报警的原因,即机油泵内转子驱动面间距和转子安装槽深度均超差,影响了机油泵性能。当发动机转速突降时,机油泵泄油量增大,机油压力低报警。     

SD2100型柴油机机油泵改进

本文针对SD2100型柴油机机油压力安全裕度稍低的问题,对机油泵部件在设计、装配、试车及售后服务全过程进行了跟踪,综合分析了对机油泵性能有影响的因素,从中找出了主要原因,对机油泵进行了结构改进设计并重新设计了模拟试验台,增加检测项目,找到了解决问题的有效措施并运用到实际生产中。装配试车试验和市场信息反馈显示,机油压力低现象明显减少。     

可变排量机油泵在发动机上的节油研究

为保证怠速工况下合理的机油压力,减少发动机热怠速异响,需要充分平衡机油泵的转排量。设计者在兼顾热怠速工况下机油压力,无疑造成了低温或高速工况下较大的液压功损失,从而引起发动机摩擦功增大,油耗增加。可变机油泵可以解决这一问题,因此受到越来越多厂家的青睐。本文对机油泵的摩擦功构成进行分析,对可变机油泵的节油原理进行了阐述,并通过台架测试,验证了同排量固定机油泵与二级可变排量机油泵在1.2TDG发动机上的节油表现,二级可变排量机油泵对油耗的贡献为,在转速2 000 r/min及油温9 0℃的状态下,摩擦功节省1.07%;有效燃料消耗率受发动机系统机油压力的影响较大,在90℃机油温度,发动机转速2 000 r/min,平均有效缸内压力为0.2 MPa工况下,系统机油压力每降低0.1 MPa,燃油消耗率可以降低6 g/(kW·h)。     

发动机润滑系统典型组成部件工作性能的试验研究

在各自专用试验台上，参照相应标准规范要求，分别对发动机润滑系统典型组成部件机油泵、机油滤清器和机油冷却器的工作性能进行了试验研究。试验重点考察了机油温度、机油泵转速以及出油压力等因素对机油泵供油特性的影响，分析了在各种温度下机油流经滤清器和冷却器时机油流量与其所产生的压降之间的关系。研究结果可以为发动机润滑系统设计和分析提供参考。     

机油泵建压时间改善

机油泵改进之后,在冷试过程中出现了机油压力建立时间延长的问题,严重影响生产节拍。通过对机油泵自身的分析和生产过程的研究,最终通过优化发动机机油加注设备,改善了冷试机油压力建立的时间。     

机油泵油腔结构优化对柴油机进机压力的影响及试验

针对舷外机用竖轴柴油机在台架试验中出现机油压力偏低的问题展开分析与研究。在排除机油泵加工尺寸偏差、机油泵主油道孔径偏小等故障因素后,初步判定机油泵油腔存在内漏为故障原因。对机油泵腔结构进行优化设计,增加油腔大端密封区宽度,减小进排油腔连通时间及截面,避免油液倒流回油腔,减少机油外泄。整机试验与耐久试验结果表明,优化后的机油压力明显高于优化前的机油压力,机油压力变化较为平缓,在高转速、大转矩下机油压力明显提高。     

发动机机油温度过高的原因分析及改进

为解决某发动机润滑系统功能试验中出现的机油温度过高问题,根据发动机润滑系统原理,通过台架试验和仿真计算对旁通阀常开、摩擦副间隙、机油泵流量及结构、机油冷却器散热量、油底壳材质等可能造成机油温度高的因素进行排查及分析,并对机油冷却器进行改进。结果表明：机油泵流量偏大、结构不合理及机油冷却器散热能力差是机油温度过高的主要原因;采用小流量的机油泵、增加机油冷却器的层数、在机油冷却器壳体增加导流筋,可以提升机油冷却器的散热能力及水流场的均匀性,降低机油温度。该研究可以为降低发动机机油温度、提高发动机可靠性提供参考。     

内燃机机油泵供油特性的试验研究

通过试验分析了机油温度、机油泵转速以及出油压力等因素对机油泵供油特性的影响，并分析了在各种工况下这些影响因毒之间的联系。研究表明，机油泵转速对机油泵供油特性的影响最明显，出油压力的影响次之，温度的影响最弱。机油泵的供油量随着转速的增加而增加，随着机油温度的升高或出油压力的增大而稍有下降。     

机油泵限压阀工作压力反馈控制方式研究

本文阐述了机油泵限压阀工作压力的两种不同的反馈调节方式,并通过试验分析不同的限压阀工作压力反馈方式的发动机机油压力分布规律,总结出机油泵限压阀采用主油道机油压力反馈控制,发动机高速运转时的主油道机油压力受机油温度和油道阻力影响小,机油压力更加稳定,能够对发动机主油道机油压力实施精确的控制,特别是对发动机低温运行工况机油压力过高和旧机油滤清器机油压力过低有很大改善.     

高原柴油机机油压力低的分析及改进

针对高原地区柴油机机油压力偏低的问题,通过理论分析和试验测试,对机油系统各处的机油流动损失进行研究;对柴油机机油系统进行设计改进,经试验验证。结果表明,大气压力对柴油机机油系统的油压起关键作用,随着海拔升高,大气压力下降,机油泵前的压力也随之下降。采用改进方案后,柴油机不但在高转速时油压保持稳定,在低转速时,柴油机机油压力也提高13%左右。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.