Refinement of Engine in-cycle losses of Parasitic and Errant Dynamic Nature (Encyclopaedic)

英国的汽车工业仍然是整个国家研发足迹中的关键战略部门之一，雇佣了大约160,000人（38,000人从事赛车运动）。英国是许多全球原始设备制造商的所在地，通过建立重要的技术中心，代表了该国研发领域最大的外来投资。受严格的排放要求（欧4：指令98/70/EC和修正案：70/220/EEC）和噪音污染目标（欧盟：指令70/157/EEC和修正案：2007/34/EC，美国：FHWA-HEP-06-020）的影响，发动机效率的提高已经成为汽车制造商的重中之重。一个有效的方法是减少摩擦（寄生）和机械（错误的动态）损失，占损失能量的15 / 25%。异常动力损失是指惯性不平衡和结构变形，也会造成噪声和振动污染。最大的机械损失是由于活塞的平移不平衡和曲柄系统的旋转不平衡，以及由于对高输出功率重量比的要求而增加的发动机粗糙度。发动机粗糙度是指轻阻尼发动机系统的结构振动。在停止启动或其他瞬态事件中，系统动力学和发动机子系统的摩擦学行为之间的相互作用起着重要作用，这是摩擦损失最严重的情况（Andersson bb0）。内燃机中近一半的摩擦损失源于活塞环与气缸的接触，约占50% (Blau et al[3])，其中三分之二可归因于压缩环。迄今为止，摩擦损失和机械损失之间的相互作用还没有得到应有的基本分析。随着对高性能发动机需求的增加，活塞承受更高的载荷，从而增加了损失。与此同时，发动机的发展受到高燃油效率和输出功率重量比以及减少氮氧化物和颗粒排放的推动。这些要求经常导致对燃烧、系统动力学和摩擦学性能的冲突要求。值得注意的是，仅减少4%的寄生损失就可以使燃油效率提高1%。英国领海的化石燃料储量迅速减少，开采难度加大，再加上大量车辆排放对环境的不利影响，这使得通过减少寄生损失来提高燃料效率成为国家的当务之急和首要目标。虽然已经开展了大型的国家项目来开发有效的燃烧策略，但迄今为止还没有开展大型的联合项目来研究活塞连杆曲轴子系统的摩擦学和动力学，这对发动机的损失有很大的影响。该项目将汇集动力学、表面工程、接触力学、润滑剂流变学和摩擦学领域的专家，共同为这一具有挑战性的多学科问题提供独特而新颖的解决方案，这对英国汽车工业至关重要。将这些相互关联的学科纳入统一分析框架的方法称为多物理场。这意味着一个跨越所有相互作用学科的单一集成项目，可以处理从大位移动力学到部件的小热弹性变形，再到微尺度摩擦学接触(如EHD薄膜、以及粗糙相互作用)，以及表面纹理模式与纳米级相互作用的逐渐减少的联系，例如润滑油的分子行为，这是由于它们的物理化学和自由表面能效应。

The automotive industry in the UK remains one of the key strategic sectors in the overall national R&D footprint, employing some 160,000 people (38000 in motor sport) [1]. The UK is home to a number of global OEMs representing the largest inward investment in the country's R&D through the establishment of significant technical centres. Influenced by the stringent emission mandates (Euro 4: Directive 98/70/EC and amendment: 70/220/EEC) and noise pollution targets (EU:DIRECTIVE 70/157/EEC and amendment: 2007/34/EC, USA: FHWA-HEP-06-020) improvements in engine efficiency have assumed a high priority with automotive manufacturers. An effective way is to reduce frictional (parasitic) and mechanical (errant dynamic) losses, accounting for 15 / 25 % of lost energy. Errant dynamic losses refer to inertial imbalance and structural deformation, also contributing to noise and vibration pollution. The largest mechanical losses are due to translational imbalance of pistons and rotational imbalance of the crank system, with increasing engine roughness due to demands for high output power-to-weight ratio. Engine roughness refers to structural vibration of lightly damped engine systems. Worst conditions for frictional losses arise under stop-start conditions or other transient events, where interactions between system dynamics and tribological behaviour of engine sub-systems play significant roles (Andersson [2]). Nearly half of the friction losses in internal combustion engines originate in the piston-ring-cylinder contacts, about 50% (Blau et al [3]), two thirds of which is attributable to the compression ring. Hitherto, interactions between frictional and mechanical losses have not received the fundamental analysis that they deserve. With increasing demand for high performance engines, the piston is subjected to even higher loads and, thus, increased losses. At the same time, engine development is driven by high fuel efficiency and output power-to-weight ratio, as well as reduced NOx and particulate emissions. These requirements frequently lead to conflicting demands put on combustion, system dynamics and tribological performance. It is significant to note that a mere 4% reduction in parasitic losses can lead to 1% improvement in fuel efficiency. Rapidly diminishing fossil fuel deposits in the UK's territorial waters and the difficulty of extraction, together with the adverse environmental impact of significant vehicular emissions, make improved fuel efficiency by reduction of parasitic losses a national imperative and a paramount objective. Whilst large national projects have been undertaken for development of efficient combustion strategies, a large consortium project has not hitherto been undertaken for tribology and dynamics of the piston-connecting rod-crankshaft sub-system which contributes significantly to engine losses. This project will bring together experts in the fields of dynamics, surface engineering, contact mechanics, lubricant rheology and tribology to collectively provide unique and novel solutions for this challenging multi-disciplinary problem of utmost importance to the UK automotive industry. An approach incorporating these inter-related disciplines within a unified analysis framework is referred to as multi-physics. This points to a single integrated project across all the interacting disciplines to deal with physics on a wide range of scales from large displacement dynamics to small thermo-elastic distortion of components and further down to micro-scale tribological contacts (such as EHD films, and asperity interactions) and onto the diminishing conjunctions of surface textured patterns with nano-scale interactions such as the molecular behaviour of lubricants due to their physical chemistry and free surface energy effects.