外文翻译--悬架性能测试

Suspension performance testing The suspension system, while not absolutely essential to the operation of a motor vehicle, makes a big difference in the amount of pleasure experienced while driving. Essentially, it acts as a bridge between the occupants of the vehicle and the road they ride on. The term suspension refers to the ability of this bridge to suspend a vehicles frame, body and powertrain above the wheels. Like the Golden Gate Bridge hovering over San Francisco Bay, it separates the two and keeps them apart. To remove this suspension would be like taking a cool dive from the Golden Gate: you might survive the fall, but the impact would leave you sore for weeks. Think of a skateboard. It has direct contact with the road. You feel every brick, crack, crevice and bump. Its almost a visceral experience. As the wheels growl across the pavement, picking up a bump here, a crack there, the vibration travels up your legs and settles in your gut. You could almost admit you were having fun, if you didnt feel like you were gonna toss your tacos at any second. This is what your car would feel like without a suspension system. In the interests of road safety, it is logical to include in periodic roadworthiness tests an inspection of vehicle suspension performance. The results of tests with a prototype machine are presented and a specification proposed for a valid suspension test. Demonstrations organized by the European Shock Absorbers Manufacturers Association ( EuSAMA) in many countries have drawn attention to the importance of correctly functioning shock absorbers. In the United Kingdom it is anticipate that the Department of the Environment will include a specific shock absorber check in the MOT Test with effect from January 1977. Of the machines currently available for testing shock absorbers without removing them from the vehicle, there is no real consensus of opinion concerning their validity to evaluate suspension safety objectively. But it is felt that possible more stringent legislation on European periodic vehicle tests in the future will demand a form of objective testing on equipment that is incapable of erroneous interpretation. Since its formation in 1971 EuSAMA has realized the imnportance of the problem, and initially charged its technical sub-committee with the task of examining and analyzing the various test machines then available. Two basic types of machine were offered at that time for diagnosing faulty shock absorbers. These were: Machines which lift up the wheels on an axle by about 100 mm and then let them drop. The subsequent displacements of the body on each side are recorded and the results compared with preset values for the particular vehicle and the suspension position, front or rear. Such a machine simulates a step input and records the subsequent body movements (see Fig 1). Machines which measure wheel movements induced by the exitation of the suspension through a frequency scan from above resonance frequency to zero, applied by means of a spring-supported platform under the tyre. Results are recorded in the form of wheel displacement against time. While passing through the wheel bounce resonant frequency the maximum amplitude is obtained and this is compared with preset values for the particular vehicle and the suspension position front or rear (see Fig 2). A third machine, introduced later, measures phase shift induced by the excitation of the suspension at a constant frequency and stroke, applied by means of a vibrating platform under the tyre. The phase shift between the moment of excitation and the force-reaction is recorded and the result is compared with preset values for the particular vehicle and suspension position (see Fig 3). These systems have three fundamental drawbacks: A: The actual damping is compared with the original damping the limit being a certain degradation in comparison with the original performance. The original performance, however, can already be marginal. B: The problems of limit setting, namely by whom should the limits be set and what are the criteria they should about? At present there is hardly any relation between set limits and acceptable performance in practice. C: The practical problem of various limits for different vehicle types and their suspensions. This requires comprehensive reference manuals that need continuously updating. Despite these fundamental drawbacks, examples of the ? widely used test machines were put through their paces by the Automotive Engineers Laboratory of the University of Ghent, as well as by several EuSAMA members. As expected, the first conclusion is that no test method which does not include dismantling the shock absorbers from the vehicle is able to furnish information concerning the shock absorber alone, and it is in fact the whole of the vehicle suspension system that is tested. This can be considered as a positive aspect of testing, since the whole of the suspension should be in good condition for safety； although the shock absorber is the component most likely to deteriorate with use, other defects such as incorrectly inflated tyres, broken springs or seized ball-joins should if possible be diagnosed. Of the other factors which influenced test results it was found that all machines gave results that were much affected by shock absorber temperature. In the case of the drop type testing machines, defects in shock absorbers caused by high frequency excitation could not be detected. With the frequency scan type of machine, approximately constant force input implies a big difference in results between vehicles with soft or hard suspension, so that changes in springs from normal to heavy duty (which the operator may be incapable of identifying ) can considerable affect the result. Each make of machine had its own characteristics, but as the basic test principles were considered to be unacceptable these details will not be presented here. After due consideration the technical sub-committee advised the General Assembly of EuSAMA that although the existing machines, when correctly operated, could help to diagnose many faulty shock absorbers, a responsible association could not authorize such equipment as the parameters measured were not considered technically representative of any particular aspect of roadworthiness. Taking brake testing as an example, it was noted that test machines give a direct reading of braking efficiency as a percentage of g without the need to identify vehicle type or to use reference manuals. Similarly, minimum braking performance levels can be set for all automobiles irrespective of model, so that a customer knows immediately if his brakes need attention, Some machines show brake imbalance, but do not indicate which component is faulty. Applying the same principles to vehicle suspension, it should be possible to propose a test which furnishes a direct reading as a value or preferably as a percentage, to indicate whether a suspension is considered satisfactory from the viewpoint of safety. Moreover, this must be achieved objectively, that is to say without need of any identification, interpretation or reference to manuals by the test operator. The technical sub-committee therefore looked for a parameter which could be considered a suitable criterion of safety in relation to vehicle suspension. As stated earlier, there is only one component normally subject to deterioration with use the shock absorber. So the role of the shock absorbers must first be defined. These have two functions to perform: to damp the movement of the vehicle body on its springs and to control wheel bounce. The permitted movement of a vehicle body on its springs is very much a matter of taste, and it is largely in the control of such movement that a sports shock absorber differs in damping characteristics from a shock absorber aimed at optimum comfort. The movement of a body on its springs does, of course, materially influence roadholding but in reality few ordinary drivers are capable of reaching the limits of the modern car in this respect, so the value of body damping is relatively unimportant for safety measurements. In any case, most drivers of a vehicle with poor body damping will quickly limit their speed and manoeuvres to the vehicles handling capacity. Wheel bounce, on the other hand, is a measurable phenomenon and the dangers of vehicles with uncertain wheel contact are well known. Both cornering and braking performance are well known. Both cornering and braking performance are limited by tyre anherence to the road； this is dependent on the vertical wheel contact as well as the tyres own properties. A parameter which permits the objective measurement of one aspect of roadholding, and therefore of vehicle suspension safety, was thus isolated but it was still necessary to be able to express it in terms that could be readily interpreted.It was proposed, therefore, to measure the minimum remaining vertical contact force between tyre and road under a given excitation at wheel-bounce frequency and to express it as a percentage of the static wheel load. Such a possibility was discussed at a meeting between the technical sub-committee and Dr Verschoore of the University of Ghent. A general concensus of opinion in favour of such a test was reached, though some members expressed doubts concerning the possibility of measuring this parameter in practice, as well as doubts concerning the results Aparamet。 . At a later date the sub-committee was informed that a prototype machine of German origin, using approximately the principle outlined above, had been submitted for evaluation to the University of Ghent. After certain recommended modifications had been performed, tests by both the University of Ghent and a member company of EuSAMA demonstrated the possibilities of such a test, and amply justified the technical sub-committees decision concerning the parameter to be measured. Details are given below of the tests performed and the results obtained on a prototype machine, developed by Maschingfabrik Koppern & Co, Hattingen, West Germany, and presented by courtesy of S A Monroe International, Brussels, Belgium. The machine (see Fig 4) Wheel movement is induced by excitation of the suspension through a frequency scan from about 25 Hz to 0, applied by a platform under the tyre, moving with a fixed stroke of 6 mm. One wheel is tested at a time. Results are recorded in the form of Minimum dynamic wheel load *100% Static wheel load The testers analogue read-out showed deviations from the maximum dynamic force indicated on the oscilloscope. Test readings are compared with the impressions of an experienced test driver because no scientific test method for roadworthiness has yet been approved. The final determination of roadworthiness and vehicle comfort is still done by vehicle manufactures by the subjective assessment of one or more experienced test drivers. The test method outlined below will indicate in nearly all cases whether a vehicle suspension is roadworthy or not. Nevertheless, a visuall inspection of the suspension elements is recommended in addition to the performance test, as incipient failures can sometimes be detected visually before performance deteriorates. Secondly, the test is of the vehicle suspension, wheel by wheel, and will indicate only whether there is a fault； it will not locate the fault, though a skilled operator may be able to diagnose certain defects from the test read-out. Obviously there is a requirement to design a machine able to detect when a certain percentage of static friction is exceeded. Development work in this area is still required. While there have been enhancements and improvements to both springs and shock absorbers, the basic design of car suspensions has not undergone a significant evolution over the years. But all of thats about to change with the introduction of a brand-new suspension design conceived by Bose - the same Bose known for its innovations in acoustic technologies. Some experts are going so far as to say that the Bose suspension is the biggest advance in automobile suspensions since the introduction of an all-independent design. How does it work? The Bose system uses a linear electromagnetic motor (LEM) at each wheel in lieu of a conventional shock-and-spring setup. Amplifiers provide electricity to the motors in such a way that their power is regenerated with each compression of the system. The main benefit of the motors is that they are not limited by the inertia inherent in conventional fluid-based dampers. As a result, an LEM can extend and compress at a much greater speed, virtually eliminating all vibrations in the passenger cabin. The wheels motion can be so finely controlled that the body of the car remains level regardless of whats happening at the wheel. The LEM can also counteract the body motion of the car while accelerating, braking and cornering, giving the driver a greater sense of control. Unfortunately, this paradigm-shifting suspension wont be available until 2009, when it will be offered on one or more high-end luxury cars. Until then, drivers will have to rely on the tried-and-true suspension methods that have smoothed out bumpy rides for centuries. 悬 架性能测试 悬架系统虽不是汽车运行不可或缺的部件，但有了它人们可以获得更佳的驾驶感受。简单的说，它是车身与路面之见的桥梁。 悬架的行程涉及到悬浮于车轮之上的车架，传动系的相对位置。就像横跨于旧金山海湾之上的金门大桥，它连接 了海湾两侧。去掉汽车上的悬架就像是你做一次冷水潜泳通过海湾一样，你可以平安的渡过整个秋天，但会疼痛会持续几周之久。 想想滑板吧！它直接接触路面你可以感受到每一块砖，裂隙及其撞击。这简直就是一种令人全身都为之震颤的体验。当轮子滑过路面时，就会在此产生震动，冲击，这种震动的旅程时对你的身体和勇气的检验。如果你没感到随时都有被掀翻之势，那么你或许会乐在其中吧！这就是你会在没有悬架的汽车上将会体验到的。 为了道路交通安全，包括定期检查车辆暂停行驶性能测试是顺理成章的事。原型试验结果与机载和规格提出有效悬架系统的测试 。 示威活动是由欧洲减震器制造商协会 (EUSAMA)，正确运作减震器已经引起了许多国家重视 .。估计英国早在 1977 年 1 月起，环境部就进行了检查减震器的 MOT测试。 现在减震器机车里的测试仪器，就其实质效力及安全的客观评价就没有达到共识 .。但人们认为，欧洲可能用更严厉的法律手段定期检验将来的一 种 客观需求测试设备无法解释的错误。 自 1971 年成立， EuSAMA 就认识到了该问题的重要性，并组成了最初的技术小组，负责研究和分析测试仪器。 有两个基本类型的机器提供了当时减震器故障诊断。包括： 1. 吊机，在轴的车轮约 100 毫米处，然后让它们落下。接着记下他们各自的位置，然后和预定的前方或后方车辆暂停位置比较。这种模拟机向前迈了一大步，并记录了实体运动情况 (参看图 1). 这些措施调动机轮，引发暂停，从上述共振频率为零位置扫描。采用了支持平台下的轮胎 .。成绩记录结果与车轮时间不符。 同时，把车轮弹跳沉最高频率和前方或后方的特殊车辆预定暂停位置进行比较。 下面要介绍的第三种机器，通过应用组件的平台下轮胎，引发了暂停或不断的频率阶段措施。时刻激励部队记录结果，并和特殊车辆预定的暂停位置比较。 这些系统有三个基本的缺点： .与 原来的阻尼表现比较而言，实际的阻尼出现了一定的退化。 原来的表现，已经是在边缘了。 .设定上限的问题，即应该由谁来定限额的标准应该是什么呢 ? 目前在实践中设定的范围和可接受表现之间几乎没有任何关系 .对不同类型的车辆的悬架系统和实际存在的各种各样的中断，它们的界限会有所差别。这就需要全面参考手册并不断更新。 尽管该系统有这些根本的弊端，但是他们的根特大学实验室工程师，以及几位 Eusama 成员已经开始使用测试仪器。正如所料，第一个结论是，没有检验方法是可以不包括拆除汽车减震器就能够提供有关资料和减震器单的 ，但实际上整个汽车停止系统是通过了测试 .。这可以说是一个积极的方面测试，全部停止安全状况应当是良好的； 尽管减震器最有可能进一步部分使用恶化，其他缺点如夸大轮胎，或处理破城球，如果可能的话，应给予诊断。 其他影响测试结果的因素中，气温减震器影响所有机器给出的结果。对于下降型试验机减震器缺陷造成的高频激励是不能察觉的。 频率扫描型机器的出现，持续的投入意味着在用软或硬中断的车辆之间差别很大。因此从太空正常到重型任务的改变 (操作可能无法识别 )可以认为直接影响结果。 每一种机器的制造都有它自己的特征，但由于基本原 则，被认为是不可 接受的测试不会在这里出现。 充分考虑技术小组委员会建议 Eusama 的加入，虽然现有机器正确操作，可以诊断许多错误减震器、负责协会不能批准这种设备作为技术上代表某一方面性能的衡量参数。 以刹车测试为例，指出：测试仪器直接显示制动效率的百分比，无需辨 别 车型或使用参考手册 .。同样，制