铁路运输英文资料.doc

兰州交通大学毕业设计（论文）The Future TGVThis is a summary of the research and development currently going into the TGV program. Much of it revolves around the TGV NG initiative, the next step in French high speed train technology. The new research was initiated by the high speed test runs of 1989 and 1990, which showed that it would be worthwile to explore the possibility of running trains at speeds between 350 km/h and 400 km/h. The official project, led by SNCF and GEC-Alsthom (now ALSTOM, the main contractor for the TGV), was kicked off on 31 May 1990, just two weeks after the world record run.The cost of the first five years of the program was 535 million French francs (about 100 million US dollars), of which 55% was provided by GEC-Alsthom (now ALSTOM), 28% by the French government, and 17% by SNCF. The aim of the program was to have a prototype TGV NG power car on the rails by the year 2000; it was to be built as part of the TGV Duplex build, in the form of a spare power car. ALSTOM suspended development on the TGV NG in 1999, concentrating instead on a new EMU trainset design with distributed power rather than dedicated power cars. This train is expected to incorporate the research that went into the TGV NG and will have the same operating speed of 360 km/h.This and other research projects (tilt TGVs and short TGVs) aim to remove several key technological and operational barriers to higher speeds and especially to lower operational costs. Some key points are detailed below. Braking Traction Equipment Weight Reduction BrakesCurrent TGV trainsets use three brake systems: disks, dynamic brakes on powered axles, and in some cases tread brakes for emergencies. For speeds of 350 km/h and more, these conventional brakes lose their ability to stop a train in a reasonable distance and cannot perform a safe emergency stop. The basic problem is simple: kinetic energy, which must be dissipated as heat in the braking system, grows as the square of speed. Braking is therefore a major technological hurdle, which must be overcome to safely attain higher speeds in revenue service.Some preliminary ideas are applied to the TGV Duplex, the bilevel TGV introduced at the end of 1995. These constitute a first step towards higher performance braking. For this third generation TGV, dynamic braking performance is improved from 24 kN per powered truck to 30 kN , as measured in retentive effort at the rail. Brake disks have added thermal capacity, and the tread brakes on the power cars are replaced by disks located directly on the wheels. Only one brake disk is used on these powered axles, because two of them (one on each side) add weight without increasing braking capacity. This is indicative of how close these brakes are to the limits of the wheel/rail interface. Overall, these changes do not represent major technological innovations, but push the envelope of existing technologies.For the TGV NG, an entirely new brake system is needed. Adhesion at high speeds is insufficient to perform quick stops using wheels alone. The wheels tend to skid, and the brakes can overheat and wear quickly, increasing maintenance costs. Therefore, it is necessary to use a system that bypasses the wheel/rail interface. This system, the magnetic induction brake, is based on existing magnetic brake technology . Magnetic induction brakes dissipate kinetic energy of the train as heat in the rail, by way of induced eddy currents. They are only effective above about 220 km/h, because they put so much power to the rail that thermal damage to the railhead would result at lower speeds. There are several technical concerns with magnetic induction brakes. Successive brake applications by several trains over the same stretch of track could overheat the rail, resulting in operational restrictions. In addition, they apply upward forces on the track, which is not designed for such loads.A prototype of a magnetic induction brake was built and underwent testing on a TGV trainset; it provided up to 16% of the braking effort. In stowed position, the brake shoe rides 10 cm above the rail; when applied, it skims a few cm above the rail without actually touching it. Currents generated by the traction motors create a magnetic field, and the motion of the train causes circular currents to flow inside the rail. These currents produce a retarding force on the train, and are turned into heat by the internal resistance of the rail. The disk brakes are also in need of supplemental thermal capacity to sustain longer applications; this can be achieved through the use of new materials. A carbon disk/carbon pad architecture is under consideration, although such systems experience large variations in effectiveness and wear, in addition to being prone to oxydation problems. Another design is inspired by the disk brakes of airliners, using a rotor disk sandwiched between two stator disks by hydraulic pressure. This runs into problems of braking effectiveness as a function of speed, requiring sophisticated active control of another league than the simple antilock system used today. It also poses problems for maintenance, requiring disassembly for inspection. Yet another direction of research is a high-pressure carbon/carbon brake, using contact pressures an order of magnitude higher than in other designs. This technology is touted to increase the thermal capacity of each disk from the current 18.5 MJ to 45 MJ, while decreasing the weight of each truck by 500 kg. Finally, the furthest out designs call on ceramic/ceramic brake systems, which are quite far from being applicable in service.Traction EquipmentTraction for the TGV NG is to come from asychronous 3-phase AC induction motors. This choice is motivated by simplicity of maintenance, very high power to weight ratio (around 1 kW/kg), and higher RPM limit. The 2 x 6000 kW traction package, 40% more powerful than 2nd generation units, requires that a total of 6 powered trucks be used instead of the usual 4, so that sufficient tractive effort can be put to the rail despite the low axle load. The extra two powered trucks are located under the first and last trailer, immediately adjacent to the power cars, as used for the TGV Eurostar. The trainset is designed to be capable of starting on a 4% grade with two traction motors shut down. Cooling of the traction equipment must remain effective at ambient temperatures up to 45 degrees C , using an environmentally friendly liquid coolant for the semiconductors rather than freon. Traction motors are individually controlled, whereas they were previously controlled in pairs using one inverter. Reactive currents generated by a trainset must be under 1 amp, to avoid perturbing the cab signal and communications channels in the rails; this is in comparison to the 15 amps of a TGV Atlantique trainset. Overall, there is nothing radically new in the traction equipment; the big challenge lies with satisfying a very large power and tractive effort requirement, within drastic axle load constraints.Cutting Down WeightAxle loads become a critical constraint at high speeds, in order for maintenance costs of track and train to be reasonable. The current axle load limit is 17 metric tons, and there is a possibility that this will be reduced to 16 tons for the faster TGV NG. Meanwhile, it is desirable to retain an articulated design (with two axles per trailer), a bilevel seating arrangement, and a host of other requirements that would tend to increase the axle load of a trainset. It turns out that keeping weight down is one of the biggest challenges for the design of the TGV NG or a potential tilting TGV.The first approach to reducing weight is new materials. For the TGV Duplex car bodies, aluminum is used. The trailers are a monocoque design assembled out of extrusions, yielding a weight reduction of 20% over an equivalent steel structure. The frame of the power cars is made of high tensile strength steel, as in the TGV Atlantique units, for a weight reduction of 10% over lower grade steel. Stainless steel could also make an entry into the new trainsets, as well as composites. Composite materials are not used on the TGV Duplexs main structural components for reasons of cost, and also because the technology was not deemed sufficiently mature. Future TGV generations, however, could be built with a composite main structure assembled with glue. There is a research effort to explore the resistance of composite materials to the wear and tear encountered over 30 years of high-speed operation. Other weight reductions are achieved by using better paints, electrical wires with thinner insulation, and many other small measures that become significant when added together.The second way to cut weight is by using the least possible material to fulfill structural requirements, or optimization. This has become a worthwile pursuit with the advent of extensive computer finite-element analysis. The TGV Duplex is the first to really benifit from these techniques, and the TGV NG will follow suit. Several areas yield weight improvements. The connection between trailers has been completely redesigned, and is now attached to the trailer bodies rather than the truck and suspension assembly. This allows a substantial reduction in the weight of the secondary suspension, with a 400 kg savings. The Y237B truck used on todays TGV Atlantique has been redesigned, saving 200 kg. An aluminum version was tried, but is not ready to be integrated into the TGV NG. The interior, as with commercial transport airplanes, is designed to be feather weight. Seats have been entirely redesigned for the TGV Duplex, with each one going from 26 kg to 14 kg , yielding a full 1000 kg reduction for each trailer.未来的TGV这是一个大概的研法，目前正进入高速列车计划。计划的许多都围绕着TGV-NG的开发，这是下一阶段法国高速列车的的技术。新的研究开始于1989年和1990年的高速试验，这个试验表明有价值去探讨列车运行速度在350千米/小时到400千米/小时的可能性。正式项目由法国国营铁路公司和通用斯通（现为阿尔斯通，TGV的主要承包商）运营。并于1990年5月31日举行了揭幕仪式，两个星期之后，诞生了高速列车运行的世界纪录。第一个五年计划的费用是535万法郎（大约100万美元），其中55%由通用斯通承担，28%由法国政府承担，15%由法国国营铁路公司承担。项目的目的是设计一个在2000年使用的高速动力车的模型，它将以备用动力车的形式作为复式列车的一部分建造。阿尔斯痛公司在1999年暂停了TGV-NG的开发，而投入到新的动力分散式而非动力集中式的电力动车组的设计。这种将继续包括TGV-NG的所有技术，和同样以360千米/小时的运行速度。这些研究项目的目的是解决一些列车在高速运行时的关键技术和业务障碍，特别是降低运行成本的问题。一些要点详述如下：制动、牵引设备、车体减重。制动器目前TGV车组使用三种制动形式：盘型制动，电阻制动，和在一些紧急情况下使用的闸瓦制动。当速度在350千米/小时或更高时，常规制动无法使列车在有效的距离内停止，更无法执行急刹车。基本问题很简单，因为以速度的平方增长的动能必须以热能的形式消除在制动系统中，因此制动是一个重要的技术关卡，而且在列车高速运行时必须保持正常的工作。一些初步的构想用于在1995年年底出现的复式TGV，促使迈出追求更高的制动性能的第一步。第三代TGV把作为衡量连续工作指标的动态制动性能从24KN提高到30KN。制动盘增加了热容量，动力车的 闸瓦制动被直接作用在车轮上的盘型制动所取代。因为二个制动盘只增加重量而没有增加制动力，所以只有一个制动盘对动轴起作用。这表明制动是怎样受到轮轨接触面的限制的。总而言之，这些改变并不代表着重大的技术革新，但是推动着现有技术的完善。TGV-NG需要一个全新的制动系统，仅仅靠轮轨之间粘着力所产生的制动力不能使高速行使的列车迅速停止。轮对将出打滑，制动器的过热和迅速磨损。增加的维修费用。因此有必要使用一种绕过轮轨间接触的系统。这种系统就是电阻制动，基于现有的电磁制动技术。电阻制动是利用涡流感应将列车的动能以热能的形式散发在轨道上。他们只能在220千米/小时以上的速度起作用。因为把大量的力作用给钢轨，对钢轨造成的热伤害将降低轨道的运行速度。有几个电阻制动的技术问题，在同一轨道上多节列车的连续可能回使轨道过热，导致轨道性能受限。此外，还会产生吸力使轨道向上变形，而轨道并没有做承受这样的载荷的设计。电阻制动系统的模型建成并经过TGV动车组的测试，它提高了16%的制动力。在布置位置上，闸瓦距离轨道在10厘米以上，而使用电阻制动系统时，虽然距离轨道只有几厘米，但并没有真正碰到它。牵引电机的电流所产生的磁场和列车的移动形成圆形的电流流向轨道内侧，这些电流产生了列车的制动力和轨道因内阻而产生的热量。盘型制动也需要增加热容量，以保持长时间的制动效果。这可以通过使用新型材料来实现。一种含碳的制动盘和含碳的垫零件正在考虑使用。除了容易被氧化外，这些材料在磨损和效果方面有很大的变化。另一种设计的来源是飞机的制动盘，使用液压转子制动盘，夹在两个定子制动盘之间。比起今天使用的简单的防抱死系统，这里遇到了有效的制动作为一种控制速度