计入冷却液时汽缸套振动特性和穴蚀的研究

研究了计人冷却液时汽缸套穴蚀计算的模型;探讨了在任意力作用下的动力响应计算中,用杜哈曼积分求解解耦方程的问题,以12V180和16V240柴油机为例,按不同约束情况进行了振动计算和分析。     

柴油机汽缸套穴蚀和振动特性的研究

以12V180型柴油机的汽缸套为例,用有限元法对该缸套进行了动力分析,并对引起缸套振动的活塞冲击力的处理进行了探索性的研究。本文从研究缸套计算模型的建立入手,对不同疏密程度网格的计算精度进行了比较,最后选定了144个节点的缸套计算模型作为进一步分析的基础;对不同壁厚、不同支承刚度、不同O型密封圈刚度和O型密封圈不同位置等多种因素的变化对缸套振动特性的影响分别进行了研究,为今后柴油机汽缸套的设计提供了一定的理论依据。     

谈火花塞不跳火

根据火花塞不跳火现象的危害 ,阐述了火花塞不跳火的常见原因及其诊断方法 ,介绍了火花塞不跳火故障的排除步骤。     

Experimental research on spray and combustion characteristics of the third generation conical spray

A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.     

Particulate matter in marine diesel engines exhausts: Emissions and control strategies

Marine diesel engines emit particles that have a complex nature, being composed by carbonaceous particles, with size spanning from few nanometres to less than one micron, and inorganic particles of micron size mainly made by ashes and sulphates.On a global scale, international shipping is responsible for few percentages of the particulate matter emissions, which also affect climate, but the regional distribution of naval traffic suggests the insurgence of significant exposure risk for population living along the coastal areas, due to chronic exposure effects. Specific strategies should be implemented to reduce the emissions of all the components of particulate matter. This paper aims to present a survey on the current and innovative strategies to remove particles from marine diesel engine exhausts, along with a critical review of the most recent findings on ships emitted particles. Evidences on physical–chemical properties, toxicology and emission factors of the particles were reported. This survey indicates that several strategies can provide a significant reduction of particulate matter emissions from ships and integration between innovative after-treatment systems, ships design and operation procedures can potentially lead to overall reduction of more than 99% even with parallel fuel savings.     

Energy factors for flexible fuel engines and vehicles operating with gasoline-ethanol blends

This work investigates the energy factors for fuel conversion from the analysis of brake specific fuel consumption (BSFC) maps of a sample of 15 engines, representative of 75% of current models available in the Brazilian market. The method also employs the engine driving patterns of power output versus crankshaft speed obtained from bench dynamometer tests. The energy factors obtained from the engine analysis was validated against experiments carried out with two production vehicles in laboratory tests following the 1975 US Federal Test Procedure (FTP-75) procedure and road tests following 16 different urban and highway routes. The fuels used in the tests were hydrous ethanol (E100, 6 v/v % water) and a blend of 22 v/v % anhydrous ethanol and 78 v/v % gasoline (E22). The energy factors found from the 3D engine BSFC map analysis were higher than those obtained from the Willans line, currently adopted as a standard, by 52% for E22 and 57% for E100. The results from the 3D engine BFSC maps and the first vehicle following the FTP-75 cycle and 15 road routes were similar, also close to the results from the second vehicle, qualifying them to be representative of modern flexible fuel spark ignition engines and vehicles.     

Ignition models and simulation of solid propellant of thermodynamic undersea vehicle

The starting characteristics of thermodynamic undersea vehicle systems are determined by the geometry, size and combustion area of solid propellants, which directly effect liquid propellant pipeline design. It is necessary to establish accurate burning models for solid propellants. Based on combustion models using powder rings and two different solid ignition grains, namely star-shaped ignition grains and stuffed ignition grains, a mathematic model of the ignition process of the propulsion system was built. With the help of Matlab, a series of calculations were made to determine the effects of different grains on ignition characteristics. The results show that stuffed ignition grain is best suited to be the ignition grain of a thermodynamic undersea vehicle system.     

对某机车厂引进柴油机机体加工系统的经济评价

本文利用现值原理和投资回收理论,计算了不同方案的长期差量成本现值的差异及差量成本当年的差异.有效地解决了某厂引进设备的经济可行性问题.文中构造的评价模型具有一定的普遍意义.     

新型无节气门进气系统--串联气门速度控制系统

为了改善车用汽油机在城市路况下（即中小负荷的工况下）的燃油经济性,设计了一种由两个串联进气门组成的进气控制系统（SVSC）,采用全新的进气控制原理,不通过节气门的操控来降低部分负荷工况下发动机进气损失并提高燃油经济性。仿真计算与试验表明,SVSC 系统可大幅减少发动机部分负荷下的进气损失,并且不需要对发动机的尺寸或结构作较大改动。     

丰田凯美瑞发动机点火系统原理与故障排除实例

针对广州丰田凯美瑞轿车一例特殊故障——发动机高速运行之后抖动、动力下降,着重分析其发动机点火系统的工作原理,并对故障现象作逐步的诊断和分析,最终排除故障。