3000中英文翻译.doc

汽车消声器的研究汽车消声器的研究背景随着汽车工业的迅速发展，人们对于汽车的舒适性和振动噪声控制的要求越来越严格。据国外有关资料表明，城市噪声的百分之七十来源于交通噪声，而交通噪声主要是汽车噪声。它严重的污染者城市环境，影响着人们的生活、工作和健康。所以噪声的控制，不仅关系到乘坐舒适性，而且还关系到环境的保护。然而一切噪声又源于振动，振动能够引起某些部件的早期疲劳损坏，从而降低汽车的使用寿命；过高的噪声技能损害驾驶员的听力，还会使驾驶员迅速疲劳，从而对汽车行驶安全性构成了极大的威胁。所以噪声控制，也关系到汽车的耐久性和安全性。因此振动、噪声和舒适性这三者是密切相关的，既要减小振动，降低噪声，又要提高乘坐舒适性，保证产品的经济性，使汽车噪声控制在标准范围之内。噪声评价指标主要是指车内、外的噪声值和振动适应性。评价方法可分为主观评价和客观评价。影响汽车噪声主观评价的主要因素是舒适性、响度和确定性，例如可以利用语义微分法进行主观评价。在客观评价时，可以采用PCNM噪声装置测量试验进行分析；此外模拟技术中的有限元法（FEM）和边界元法（BEM）也被广泛应用。降低发动机噪声是汽车噪声控制的重点。发动机是产生振动和噪声的根源。发动机的噪声是由燃料燃烧，配气机构，正时齿轮及活塞的敲击噪声等合成的。降低发动机本体的噪声就要改造振源和声源，包括用有限元等方法分析设计发动机，选用柔和的燃烧工作过程，提高机体的结构刚度，采用严密的配合间隙，降低汽缸盖噪声。例如在油底壳上增设加强筋和横隔板，以提高油底壳的刚度，减少振动噪声。另外，给发动机涂阻尼材料也是一个有效的办法。阻尼材料能把动能转变成热能。进行阻尼处理的原理就是将一种阻尼材料与零件结合成一体来消耗振动能量。它有以下几种结构：自由阻尼结构、间隔自由阻尼层结构、约束阻尼层结构。它的采用明显的减少了共振的幅度，加快了自由振动的衰减，降低各个零件的传振能力，增加了零件在临界频率以上的隔振能力。目前，已有一些国家的专家设计了一种发动机主动隔振系统，用于减少发动机振动，以达到降低噪声的目的。 对于汽车噪声的控制，除了在设计上使用优化方法和零件的优化选用以外，还可以对噪声进行主动控制。这就是以声消声技术，原理是：利用电子消声系统产生与噪声相位相反的声波，使两者的振动相互抵消，以降低噪声。这种消音装置采用极其先进的电子元件，具有优异的消声效果，可以用于降低车内噪声、发动机噪声，还可以用于主发动机支撑系统，以抵消发动机振动噪声。汽车消音器的原理就是其排气管是由两个长度不同的管道构成，这两个管道先分 开再交汇。由于两个管道的的长度差值等于汽车所发出的声波的波长的一半，使得两列声波在叠加时发生干涉时相互抵消而减弱声强，使声音减小，从而起到消音的效果。 阻性消声器主要是利用多孔吸声材料来降低噪声的。把吸声材料固定在气流通道的内壁上或按照一定方式在管道中排列，就构成了阻性消声器。当声波进入阻性消声器时，一部分声能在多孔材料的孔隙中摩擦而转化成热能耗散掉，使通过消声器的声波减弱。阻性消声器就好象电学上的纯电阻电路，吸声材料类似于电阻。因此，人们就把这种消声器称为阻性消声器。阻性消声器对中高频消声效果好、对低频消声效果较差。 抗性消声器是由突变界面的管和室组合而成的，好象是一个声学滤波器，与电学滤波器相似，每一个带管的小室是滤波器的一个网孔，管中的空气质量相当于电学上的电感和电阻，称为声质量和声阻。小室中的空气体积相当于电学上的电容，称为声顺。与电学滤波器类似，每一个带管的小室都有自己的固有频率。当包含有各种频率成分的声波进入第一个短管时，只有在第一个网孔固有频率附近的某些频率的声波才能通过网孔到达第二个短管口，而另外一些频率的声波则不可能通过网孔只能在小室中来回反射，因此，我们称这种对声波有滤波功能的结构为声学滤波器。选取适当的管和室进行组合就可以滤掉某些频率成分的噪声，从而达到消声的目的。抗性消声器适用于消除中、低频噪声。 把阻性结构和抗性结构按照一定的方式组合起来，就构成了阻抗复合式消声器。微穿孔板消声器一般是用厚度小于1mm的纯金属薄板制作，在薄板上用孔径小于1mm的钻头穿孔，穿孔率为1%一3%。选择不同的穿孔率和板厚不同的腔深，就可以控制消声器的频谱性能，使其在需要的频率范围内获得良好的消声效果。小孔消声器的结构是一根末端封闭的直管，管壁上钻有很多小孔。小孔消声器的原理是以喷气噪声的频谱为依据的，如果保持喷口的总面积不变而用很多小喷口来代替，当气流经过小孔时、喷气噪声的频谱就会移向高频或超高频，使频谱中的可听声成分明显降低，从而减少对人的干扰和伤害。 有源消声器的基本原理是在原来的声场中，利用电子设备再产生一个与原来的声压大小相等、相位相反的声波，使其在一定范围内与原来的声场相抵消。这种消声器是一套仪器装置，主要由传声器、放大器、相移装置、功率放大器和扬声器等组成。 消声器的主要结构形式汽车消声器按消声原理与结构可分为抗性消声器、阻性消声器和阻抗复合型消声器三类 1. 抗性消声器 抗性消声器是在内部通过管道、隔板等部件组成扩张室、共振室等各种消声单元时，声波在传播时发生反射和干涉，降低声能量达到消声目的。抗性消声器消声频带有限，通常对低、中频带消声效果好，高频消声效果差，货车多采用抗性消声器。2. 阻性消声器 E是在内部排气通过的管道周围填充吸声材料来吸收声能量达到消声目的的消声器。对中、高频消声效果好，单纯用作汽车排气消声器较少，通常与抗性消声器组合起来使用。- 3 阻抗复合型消声器 是分别用抗性消声单元和吸声材料组合构成的消声器，它具有抗性、阻性消声器的共同特点。对低、中、高频噪声都有很好的消声效果。消声器的主要作用降低发动机的排气噪声，并使高温废气能安全有效地排出。消声器作为排气管道的一部分，应保证其排气畅通、阻力小及足够强度。消声器要经受500700高温排气，保证在汽车规定的行驶里程内，不损坏、不失去消声效果汽车消音器在现实中的作用汽车噪声主要来自汽车排气噪声。若不加消声器，在一定速度下，噪声可达100分贝以上。其次为引擎噪声和轮胎噪声，引擎噪声在汽车正常运转时，可达90分贝以上，而轮胎噪声在车速为90公里/时以上时，可达95分贝左右。因此，在排气系统中加上消声器，可使汽车排气噪声降低20-30分贝。在引擎方面，以汽油引擎代替柴油引擎，可以降低引擎噪声6-8分贝。常见故障及排除故障现象：一辆东风EQ1090D型汽车在行驶中消声器出现放炮现象，停车检查中，当把点火线圈高压总火线拔下，在距离缸体34mm处试火，扳动分电器断电触点或摇转曲轴时，跳火均正常，但发现分电器断电触点有烧蚀现象。用砂条修磨触点并调整间隙至0.35-0.45mm后，发动机启动后运转正常，但是当汽车行驶约40公里后，消声器又出现放炮现象。故障检查与排除：根据上述现象对消声器放炮原因进行了仔细分析，为找出故障症结，检查了点火次序、分电器断电触点臂弹簧力、点火正时、火花塞等均未发现问题。继续检查化油器空气滤清器、气门间隙也没结果。再次启动发动机又运转正常，但是没有多久旧病又复发了。 停车再次检查分电器部分。通过拆卸和仔细检查，终于发现断电器触点臂至低压接线柱的铜胶线在拐弯处折裂，只剩下几根细铜丝相连。更换断裂的铜胶线后，故障现象消失。故障分析：当分电器低压导线部分铜丝折断后，导线横截面积减小，从而使初级电路电阻增大，电路中电流减小，造成点火线圈产生的高压不足。当发动机温低时，虽然启动困难一些，但启动后发动机能正常运转。待发动机温度升高后，点火线圈温度随之升高，电阻又随温度上升而增大，所以点火线圈产生的高压电会更加不足，高压火花更弱，甚至断火。由于不时断火，气缸里未被点燃的可燃混合气排入消声，在消声器中膨胀时，遇到废气中的火星即发生爆燃，表现为消声器放炮。The research of car mufferThe research background of car mufflerWith the rapid development of industry, people for the car comfort and vibration noise control requirements more and more strictly. According to foreign relevant data show that seventy percent of noise from the city traffic noise, and the traffic noise is mainly automobile noise. It serious polluters of the urban environment, affecting peoples life, work and health. So the noise control, is not only related to the ride comfort, but also related to the protection of the environment. But all the noise and vibration from, can cause some parts of vibration early fatigue damage, so as to reduce the car service life; The noise of the high skill damage the drivers hearing, still can make drivers quickly fatigue, thus vehicle driving safety constitute a great threat. So noise control, but also related to the cars durability and safety. So the vibration and noise and comfort that are closely related, not only reducing the vibration, lower noise, and to improve the ride comfort, and ensure that the products economy, make the vehicle noise control in the standard range.Noise evaluation index is mainly refers to the car, the noise and vibration value adaptability. Evaluation method can be divided into subjective evaluation and objective evaluation. Impact noise subjective evaluation car is the main factor comfort, loudness and certainty, for example can use semantic differential method on subjective evaluation. In an objective evaluation, can use PCNM noise device to measure test analysis; In addition simulation technology of finite element method (FEM) and the boundary element method (BEM) is also widely used. Reduce engine noise is the focus of automobile noise control. The engine is the source of vibration and noise. The noise of the engine by fuel burning, with gas institutions, timing gears and piston percussive noise of synthesis.Reduce engine noise will transform the body vibration source and sound sources, including the use of finite element analysis and design methods of engine, choose soft combustion process and improve the body structure stiffness, the tight fitting clearance, reduce the cylinder cover noise. For example in the oil pan is adding reinforcement and horizontal clapboard, in order to improve the stiffness of the oil pan, reduce vibration noise. In addition, for engine with damping materials is also an effective way. Damping materials can put the kinetic energy into heat. On the principle of damping processing is a kind of damping materials and components combined into one to vibration energy consumption. It has the following structure: free damped structure, interval free damping layer structure, constrained damping layer structure. Its the obvious reduced the resonance of the amplitude, speed up the free vibration of attenuation, and reduce vibration of the various parts of the ability to increase the parts in the critical frequency of vibration isolation above ability.Currently, there are some countries of experts design a kind of engine active vibration isolation system, used to reduce engine vibration, in order to achieve the purpose of reducing the noise.For the car noise control, except on the design optimization method and use of the optimization of the parts choose beyond, still can active control of noise. This is the sound attenuation technology, principle is: use electronic sound system with opposite phase noise produced the sound waves, make the vibration offset each other, in order to reduce the noise. The device USES extremely advanced deadened the electronic components, with excellent silencing effect, can be used to reduce the interior noise, engine noise, can also be used for the main engine support system, in order to offset the engine vibration noise.Car muffler principle is the exhaust pipe is made from two different length of pipe form, the two pipe first points again open intersection. Since the two pipe length difference is equal to the car out of the wavelength of the sound waves half, make two columns of sound in a superposition interference occurs when each other when they weaken offset sound intensity to make the voice decrease, and play a sound effect.Resistance is the main sexual muffler porous absorption material to reduce noise. The absorption material in air passages of the fixed on the wall or according to certain in the pipe arrangement in the way, constitutes the resistance of the muffler. When sound waves into resistance when sexual muffler, part of the sound energy in porous materials of pores in the friction and into heat energy dissipation off, make the sound waves through the muffler weakened. Sex is like electrical resistance on the muffler pure resistance circuit, and the absorption material similar to the resistance. So, people took the muffler called resistance sex muffler. Resistance to high frequency of sexual muffler attenuation effect is good, the low frequency sound effect is poorer. Resistance is the interface by mutation muffler tubes and a combination of room, and it seemed to be an acoustic filter, and electrical filter similar, each with a tube of a cell is a web filter hole, pipe to the air quality in electrical inductance and equivalent resistance, called the sound quality and resistance. The small room of air volume is equivalent to the electrical capacitance, called the sound. And electrical filter similar, each with a tube of small room has its own natural frequency. When contains various frequency component of the sound into the first short tube, only in the first natural frequency of the near net mesh some of the frequency of sound waves to through the nets hole reached the second short tube mouth, but some of the frequency of sound waves is not possible through the nets hole. Only in a small room in reflected back and forth, and, therefore, we call this a sound wave filter function for the structure of a acoustic filter. Selecting proper tube and room for combination. Can filter out some frequency components of the noise, so as to achieve the purpose of the dead. Resistance is applicable to eliminate the muffler, low frequency noise. The resistance of structure and resistance structure according to certain way together, they form a complex impedance muffler.Micro-perforated panel with thickness is generally muffler 1 mm of pure metal plate making, thin plate with less than 1 mm in diameter drill perforation, perforation rate for a 3% to 1%. Choose different perforation rate and the thickness different cavity deep, can control the spectrum of the muffler performance, in the need of the frequency range for good silencing effect. The muffler structure is a small holes in the closed end roots straight pipe, tube wall drilling has many small holes through them. The principle of the holes in the jet noise muffler for the spectrum of the basis, if the total area of the same but keep spout with many small vent to replace, when air holes, jet noise when after the spectrum will move to the high frequency or uhf, make of the spectrum can listen to sound composition reduced significantly, and thus reduce the interference and damage to people. The basic principle of active muffler is in the original field using electronic equipment to produce a with the original sound pressure equal and opposite phase of sound waves, make it within a certain range and the original sound field phase offset. The muffler is a set of instruments device, mainly by microphones, amplifiers, phase shift device, power amplifier and speaker etc.The main structure form mufflerAccording to the car muffler attenuation principle and structure can be divided into resistance the silencer, sex and impedance muffler compound muffler three categories1. The resistance in internal resistance muffler muffler is through pipes, clapboard components and other parts expansion chamber, resonant chamber, etc. Various kinds of silencing unit, sound in reflection and transmission occurs when interference, reduce the energy to sound attenuation purpose. Resistance muffler attenuation band limited, usually to low, medium frequency band sound effect is good, high frequency sound effect is poor, van used more resistance muffler.2. The resistance of the internal exhaust muffler E is through around the pipeline of filling the sound-absorbing material sound absorption energy to the muffler attenuation purpose. On the high frequency, silencing effect is good, as a simple car exhaust muffler less, often combined with resistance muffler use. -3 impedance muffler is compound respectively with resistance silencing unit and absorption material that constitute the muffler, it has resistance, resistance of the common characteristics of the muffler. For low, medium and high frequency noise all have good silencing effect.The main function of the mufflerReduce engine exhaust noise, and make the hot flue gas can safely and effectively eduction. As part of the exhaust muffler pipeline, should guarantee its exhaust expedite, and small resistance and enough strength. Be subjected to 500 muffler 700 high temperature exhaust, ensure the provisions in the car trip mileage inside, do not damage, dont lose silencing effectCar muffler in real in the roleCar noise from the car exhaust noise mainly. If be not added, muffler, in a certain speed, the noise of up to 100 decibels. Next is the engine noise and tyre noise, the engine noise in the car when the normal operation, up to 90 decibels, while tyre noise in the speed of 90 miles an hour or more, can reach 95 decibel. Therefore, in the exhaust system with muffler, can make the automobile exhaust noise reducing 20-30 decibels. In the engine, to gasoline engines instead of diesel engine, can reduce engine noise 6-8 decibelsCommon fault and ruled outFault phenomenon: a car EQ1090D type dongfeng automobile in motion appear muffler while phenomenon, stop the inspection, the ignition coil when high pressure total fleet pulled from 34 mm place in cylinder try fire, wind power distributor contacts or wave turned the crankshaft, jump fire all normal, but found distributor contacts have power ablation phenomenon. Article with sand the grinding contacts and adjust the clearance to 0.35-0.45 mm, after the engine starts operation, but when the automobile driving after about 40 km, muffler appeared adopting phenomenon.Fault inspection and exclude: according to the above phenomenon of muffl