曲柄连杆 外文翻译 - 图文(2)

外文原文: Connecting rod In a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. The connecting rod was invented sometime between 1174 an 1200 when a Muslim inventor, engineer and craftsman named al-Jazari built five machines to pump water for the kings of the Turkish Artuqid dynasty — one of which incorporated the connecting rod. Transferring rotary motion to reciprocating motion was made possible by connecting the crankshaft to the connecting rod, which was described in the \of Knowledge of Ingenious Mechanical Devices\The double-acting reciprocating piston pump was the first machine to offer automatic motion, but its mechanisms and others such as the cam, would also help initiate the Industrial Revolution. Internal combustion engines In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft. The small end attaches to the piston pin, gudgeon pin (the usual British term) or wrist pin, which is currently most often press fit into the conrod but can swivel in the piston, a \wrist pin\journal on the crank throw, running on replaceable bearing shells accessible via the con rod bolts which hold the bearing \the big end; typically there is a pinhole bored through the bearing and the big end of the con rod so that pressurized lubricating motor oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings. The con rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and relaxing with every rotation, and the load increases rapidly with increasing engine speed. Failure of a connecting rod, usually called \a rod\is one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of the crankcase and thereby rendering the engine irreparable; it can result from fatigue near a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening, or re-use of already used (stressed) bolts where not recommended. Despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. This is because production auto parts have a much larger factor of safety, and often more systematic quality control. When building a high performance engine, great attention is paid to the con rods, eliminating stress risers by such techniques as grinding the edges of the rod to a smooth radius, shot peening to induce compressive surface stresses (to prevent crack initiation), balancing all con rod/piston assemblies to the same weight and Magnafluxing to reveal …… 此处隐藏：1286字，全部文档内容请下载后查看。喜欢就下载吧 ……