Analysis of the capabilities of a two-stage turbocharging system to fulfil the US2007 anti-pollution directive for heavy duty diesel engines

This article presents a two-stage turbocharged heavy-duty diesel (HDD) engine designed to fulfil the US2007 anti-pollution directive. This directive imposes very restrictive limits on the NOx and particle emissions of HDD engines. In this work, the possibility of combining particle traps in the exhaust line to reduce soot emissions with very high EGR rates to reduce NOx emissions is considered. This new generation engine implements two-stage turbocharging in order to improve the bsfc when the engine is working on steady conditions as well as to optimize the engine transient response. After carrying out the tests, the results were analyzed and the engine settings were adjusted to maximise its behaviour and minimise pollutant emissions. NOx and soot emission peaks were also analyzed at engine transient conditions in order to keep them under certain levels, and thus maintain the overall pollutant emissions to a level that is as low as possible. In summary, a double-stage turbocharging configuration can greatly improve engine driveability (between 23% and 36% depending on engine speed), while reducing NOx emissions during transient evolution without increasing opacity peaks beyond the stated limits.     

Analysis process of a steering system using a concept model for idle vibration

This paper describes the development of an optimal design process for a steering column system and supporting system. A design guide is proposed at the initial concept stage of the development process to obtain sufficient stiffness of the steering system while reducing the idle vibration sensitivity of the system. Case studies on resonance isolation are summarized, where vibration modes among the systems are separated by applying a vibration mode map at the initial stage of the design process. This study also provides design guidelines for an optimal dynamic damper system using a CAE (computer aided engineering) analysis. The damper FE (finite element) model is added to the vehicle model to analyze the relation between the frequency and the sensitivity of the steering column system. This analysis methodology makes it possible to achieve target performance in the early design stage and reduction of damper tuning activity after the proto car test stage. Through the proposed steering column system development process, a lightweight vehicle with high stiffness is possible prior to the proto build stage. Furthermore, the improved process is expected to contribute to reducing the overall development period and the number of proto car tests necessary to achieve the desired steering system performance.     

Thermal design of automobile exhaust based thermoelectric generators: Objectives and challenges

The potential for thermoelectric power generation (via waste heat recovery onboard automobiles) to displace alternators and/or provide additional charging to a vehicle battery pack has increased with recent advances in thermoelectric material processing. In gasoline fueled vehicles (GFVs), about 40% of fuel energy is wasted in exhaust heat, while a smaller amount of energy (30%) is ejected through the engine coolant. Therefore, exhaust-based thermoelectric generators (ETEG) have been a focus for GFV applications since the late 1980s. The conversion efficiency of modern thermoelectric materials has increased more than three-fold in the last two decades; however, disputes as to the thermal design of ETEG systems has kept their overall efficiency at limited and insufficient values. There are many challenges in the thermal design of ETEG systems, such as increasing the efficiency of the heat exchangers (hot box and cold plate), maintaining a sufficient temperature difference across the thermoelectric modules during different operating conditions, and reducing thermal losses through the system as a whole. This paper focuses on a review of the main aspects of thermal design of ETEG systems through various investigations performed over the past twenty years. This paper is organized as follows: first, the construction of a typical ETEG is described. The heat balance and efficiency of ETEG are then discussed. Then, the third section of this paper emphasizes the main objectives and challenges for designing efficient ETEG systems. Finally, a review of ETEG research activities over the last twenty years is presented to focus on methods used by the research community to address such challenges.     

Comparison of HC species from diesel combustion modes and characterization of a heat-up doc formulation

This study summarizes engine speed and load effects on HC species emissions from premixed charge compression ignition (PCI) and conventional diesel combustion, and it evaluates diesel oxidation catalyst (DOC) formulations on a gas flow reactor for the purpose of diesel particulate filter regeneration or lean NO_x trap desulfation. HC emissions are sampled simultaneously by a Tedlar bag for light HC species and by a Tenax TA™ adsorption trap for semi-volatile HC species, and they are analyzed by gas chromatography with a flame ionization detector. The bulk temperature and residence time during combustion are key parameters that are important for understanding the effects of speed and load on engine-out HC emissions. The degree of post-flame oxidation is higher in PCI than in conventional combustion, and it is increased for PCI with a higher speed and load, as indicated by a lower fuel alkanes/THC ratio, a higher alkenes/fuel alkanes ratio, and a higher methane/THC ratio. Ethene and n-undecane are two representative HC species, and they are used as a surrogate mixture in the gas flow reactor to simulate PCI and conventional combustion with in-cylinder post fuel injection. Among the three DOC formulations tested, the catalyst with constituent precious metals of platinum and palladium (PtPd) showed the best light-off performance, followed by PtPd with an addition of cerium dioxide (PtPd+CeO₂), and platinum (Pt), regardless of exhaust compositions. Conventional combustion exhaust composition shows a lower light-off temperature than that of PCI, regardless of catalyst formulation.     

怎样卖掉你的车

在汽车消费发达的国家，二手车消费是整个汽车消费的重要组成部分。甚至可以说，科学、合理、完善的二手车消费体制带动了整个汽车消费的发展。在今天的中国，汽车越来越多地进入了家庭，准备置换手中旧车的人也越来越多，所以《爱车》特别邀请美国二手车销售专家M.Brueggemann先生为中国的车主朋友奉献一篇精彩的文章，虽然本文充满美国社会的气息，很多技巧不能直接套用，但是先进的经验是绝对值得借鉴的。[编者按]     

Optimal synthesis of function generation in steering linkages

This paper presents an approach to optimize planar mechanisms for function generation synthesis. It is applied to the design of different steering linkages used in road vehicles where the Ackermann condition is formulated as the objective function. Four different mechanisms are kinematically defined and synthesized in terms of the proposed method. Limitations of the size of the elements are also considered by means of inequality constraints. Solutions are presented as the difference between desired behaviour, established by Ackermann, and actual generated performance. The results show that the accuracy achieved by the proposed procedure is satisfactory for working conditions in this type of linkages.     

Displacement/stress level-crossing stochastic finite element-based algorithm for reliability assessment of vehicle components with loading and material uncertainties

In the majority of the researches presented so far for behavior analysis of complex structures with random loading and material properties, the applications rather than the analysis algorithms have been extended. The present paper is devoted to extending the probabilistic concepts to achieve a stochastic finite element-based consistent reliability algorithm that is more consistent with the design criteria. The proposed procedure is very general and may be employes for vehcle components with complex geometries and load conditions. However, beam-type vehicle components experience simultaneous spatially-random loading conditions and material properties are employed to clarify the proposed algorithm, without loss of the generality. In this regard, important concepts such as the displacement/stress level-crossing concept are incorporated. The stress stochastic formulations are proposed in the present paper, for the first time.     

High-strain-rate fracture of adhesively bonded composite joints in DCB and TDCB specimens

Double-cantilever beam (DCB) and tapered double-cantilever beam (TDCB) specimens are the test configurations most commonly used to measure the fracture toughness of composites and adhesive joints. Strain rates of 1 to 18.47 m/s were applied to the test specimens via high-speed hydraulic test equipment. Because the fracture occurs through the adhesively bonded joints and the cracks grow rapidly, the crack length and beam displacement were recorded by a high-speed camera. An energy range from 0 to 10 J was often observed in the high-strain-rate fracture experiments for nonlinear plastic behavior of the dynamically loaded adhesively bonded DCB and TDCB specimens. The range of energy release rates (fracture energy) for TDCB specimen was 2 to 3 times higher than that of a DCB specimen for all high strain rates. The fracture energy of automotive adhesive joints can be estimated using the experimental results in this study for the fracture toughness (G_IC) under high rates of loading. The crack grows as the applied fracture energy exceeds the value of the critical energy release rate (G_IC) at the crack tip. The energy release rate was calculated using the fracture mechanics formula. The key fracture mechanics parameter, the fracture energy GIC, was ascertained as a function of the test rate and can be used to assess and model the overall joint performance.