膜片弹式离合器设计捷达GTI16V离合器（广工）
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广西工学院2010届毕业设计说明书 Cooling-system Service and Maintenance - - - A typical 4 cylinder vehicle cruising along the highway at around 50 miles per hour, will produce 4000 controlled explosions per minute inside the engine as the spark plugs ignite the fuel in each cylinder to propel the vehicle down the road. Obviously, these explosions produce an enormous amount of heat and, if not controlled, will destroy an engine in a matter of minutes. The purpose of the cooling-system is to keep the engine at its most efficient operating temperature at all engine speeds and all driving conditions. Cooling-system is responsible for the protection of the normal work of the engine so that the engine has a longer service life. In fact, the cooling system on a car driving down the freeway dissipates enough heat to heat two average-sized houses!But automobile can without cooling-system .In other word, Cooling-system is very important for a automobile. Two general types of cooling-system have been used on four-cycle automotive engines,air cooling and liquid cooling.Most automotive engines now employ liquid cooling.The liquid cooling system consists of water pumps,radiator,radiator cooling fans, thermostat bypass system,freeze plugs,water jackets and so on.The cooling system is made up of the passages inside the engine block and heads, a water pump to circulate the coolant, a thermostat to control the temperature of the coolant, a radiator to cool the coolant, a radiator cap to control the pressure in the system, and some plumbing consisting of interconnecting hoses to transfer the coolant from the engine to radiator and also to the cars heater system where hot coolant is used to warm up the vehicles interior on a cold day. The modern cooling system has not changed much from the cooling systems in the model back in the 20s. Oh sure, it has become infinitely more reliable and efficient at doing its job, but the basic cooling system still consists of liquid coolant being circulated through the engine, then out to the radiator to be cooled by the air stream coming through the front grill of the vehicle.Todays cooling system must maintain the engine at a constant temperature whether the outside air temperature is 110 degrees Fahrenheit or 10 below zero. If the engine temperature is too low, fuel economy will suffer and emissions will rise. If the temperature is allowed to get too hot for too long, the engine will self destruct. The most important maintenance item is to flush and refill the coolant periodically. The reason for this important service is that anti-freeze has a number of additives that are designed to prevent corrosion in the cooling system. This corrosion tends to accelerate when several different types of metal interact with each other. The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core. causing the engine to eventually overheat. The anti-corrosion chemicals in the antifreeze prevents this, but they have a limited life span. Over a period of time,rust and scale restrict radiator and engine water jackets;the rust and scale restrict the circulation of water,and the engine tends to over heart. In addition, the house and connections between the radiator and the engine many deteriorate, causing leakage or in adetorted,many not close and open properly,thus reducng the effectivenness of the cooling system. A number of tests of the mne the condition of these parts. In addition,the strength of the antifreeze solution can be tests. The National Automotive Radiator Service Association (NARSA) recommends that motorists have a seven-point preventative cooling system maintenance check at least once every two years. The seven-point program is designed to identify any areas that need attention. It consists of: a visual inspection of all cooling system components, including belts and hoses a radiator pressure cap test to check for the recommended system pressure level a thermostat check for proper opening and closing a pressure test to identify any external leaks to the cooling system parts; including the radiator, water pump, engine coolant passages, radiator and heater hoses and heater core an internal leak test to check for combustion gas leakage into the cooling system an engine fan test for proper operation a system power flush and refill with car manufacturers Visual Inspection What you are looking for is the condition of the belts and hoses. The radiator hoses and heater hoses are easily inspected just by opening the hood and looking. You want to be sure that the hoses have no cracking or splitting and that there is no bulging or swelling at the ends. If there is any sign of problems, the hose should be replaced with the correct part number for the year, make and model of the vehicle. Never use a universal hose unless it is an emergency and a proper molded hose is not available. Heater hoses are usually straight runs and are not molded, so a universal hose is fine to use and often is all that is available. Make sure that you use the proper inside diameter for the hose being replaced. For either the radiator hoses or the heater hoses, make sure that you route the replacement hose in the same way that the original hose was running. Position the hose away from any obstruction that can possibly damage it and always use new hose clamps. After you refill the cooling system with coolant, do a pressure test to make sure that there are no leaks. On most older vehicles, the water pump is driven by a V belt or serpentine belt on the front of the engine that is also responsible for driving the alternator, power steering pump and air conditioner compressor. These types of belts are easy to inspect and replace if they are worn. You are looking for dry cracking on the inside surface of the belt. On later vehicles, the water pump is often driven by the timing belt. This belt usually has a specific life expectancy at which time it must be replaced to insure that it does not fail. Since the timing belt is inside the engine and will require partial engine disassembly to inspect, it is very important to replace it at the correct interval. Since the labor to replace this belt can be significant, it is a good idea to replace the water pump at the same time that the belt is replaced. This is because 90 percent of the labor to replace a water pump has already been done to replace the timing belt. It is simply good insurance to replace the pump while everything is apart. Radiator pressure cap test A radiator pressure cap is designed to maintain pressure in the cooling system at a certain maximum pressure. If the cooling system exceeds that pressure, a valve in the cap opens to bleed the excessive pressure into the reserve tank. Once the engine has cooled off, a negative pressure begins to develop in the cooling system. When this happens, a second valve in the cap allows the coolant to be siphoned back into the radiator from the reserve tank. If the cap should fail, the engine can easily overheat. A pressure test of the radiator cap is a quick way to tell if the cap is doing its job. It should be able to hold its rated pressure for two minutes. Since radiator caps are quite inexpensive, I would recommend replacing it every 3 years or 36,000 miles, just for added insurance. Make absolutely sure that you replace it with one that is designed for your vehicle. Thermostat check for proper opening and closing This step is only necessary if you are having problems with the cooling system. A thermostat is designed to open at a certain coolant temperature. To test a thermostat while it is still in the engine, start the engine and let it come to normal operating temperature (do not let it overheat). If it takes an unusually long time for the engine to warm up or for the heater to begin delivering hot air, the thermostat may be stuck in the open position. If the engine does warm up, shut it off and look for the two radiator hoses. These are the two large hoses that go from the engine to the radiator. Feel them carefully (they could be very hot). If one hose is hot and the other is cold, the thermostat may be stuck closed. If you are having problems and suspect the thermostat, remove it and place it in a pot of water. Bring the water to a boil and watch the thermostat. You should see it open when the water reaches a boil. Most thermostats open at about 195 degrees Fahrenheit. An oven thermometer in the water should confirm that the thermostat is working properly. Pressure test to identify any external leaks Pressure testing the cooling system is a simple process to determine where a leak is located. This test is only performed after the cooling system has cooled sufficiently to allow you to safely remove the pressure cap. Once you are sure that the cooling system is full of coolant, a cooling system pressure tester is attached in place of the radiator cap. The tester is than pumped to build up pressure in the system. There is a gauge on the tester indicating how much pressure is being pumped. You should pump it to the pressure indicated on the pressure cap or to manufacturers specs. Once pressure is applied, you can begin to look for leaks. Also watch the gauge on the tester to see if it loses pressure. If the pressure drops more than a couple of pounds in two minutes, there is likely a leak somewhere that may be hidden. It is not always easy to see where a leak is originating from. It is best to have the vehicle up on a lift so you can look over everything with a shop light or flashlight. If the heater core in leaking, it may not be visible since the core is enclosed and not visible without major disassembly, but one sure sign is the unmistakable odor of antifreeze inside the car. You may also notice the windshield steaming up with an oily residue. Internal leak test If you are losing coolant, but there are no signs of leaks, you could have a blown head gasket. The best way to test for this problem is with a combustion leak test on the radiator. This is accomplished using a block tester. This is a kit that performs a chemical test on the vapors in the radiator. Blue tester fluid is added to the plastic container on the tester. If the fluid turns yellow during the test, then exhaust gasses are present in the radiator. The most common causes for exhaust gasses to be present in the radiator is a blown head gasket. Replacing a bad head gasket requires a major disassembly of the engine and can be quite expensive. Other causes include a cracked head or a cracked block, both are even more undesirable than having to replace a head gasket. When a head gasket goes bad The process of replacing a head gasket begins with completely draining the coolant from the engine. The top part of the engine is then disassembled along with much of the front of the engine in order to gain access to the cylinder heads. The head or heads are then removed and a thorough inspection for additional damage is done. Before the engine can be reassembled, the mating surfaces of the head and block are first cleaned to make sure that nothing will interfere with the sealing properties of the gasket. The surface of the cylinder head is also checked for flatness and, in some cases, the block is checked as well. The head gasket is then positioned on the block and aligned using locator pegs that are built into the block. The head is then placed on top of the gasket and a number of bolts, called head-bolts are coated with oil and loosely threaded into the assembly. The bolts are then tightened in a specific order to a specified initial torque using a special wrench called a torque wrench. This is to insure that the head gasket is crushed evenly in order to insure a tight seal. This process is then repeated to a second, tighter torque setting, then finally a third torque setting. At this point, the rest of the engine is reassembled and the cooling system is filled with a mixture of antifreeze and water. Once the engine is filled, the technician will pressure test the cooling system to make sure there are no leaks. In many engines, coolant also passes between the heads and the intake manifold. There are also gaskets for the intake manifold to keep the coolant from leaking out at that point. Replacing an intake manifold gasket is a much easier job than a head gasket, but can still take a couple of hours or more for that job. Engine Fan Test The radiator cooling fan is an important part of the cooling system operation. While a fan is not really needed while a vehicle is traveling down the highway, it is extremely important when driving slowly or stopped with the engine running. In the past, the fan was attached to the engine and was driven by the fan belt. The speed of the fan was directly proportional to the speed of the engine. This type of system sometimes caused excessive noise as the car accelerated through the gears. As the engine sped up, a rushing fan noise could be heard. To quiet things down and place less of a drag in the engine, a viscous fan drive was developed in order to disengage the fan when it was not needed. When computer controls came into being, these engine driven fans gave way to electric fans that were mounted directly on the radiator. A temperature sensor determined when the engine was beginning to run too hot and turned on the fan to draw air through the radiator to cool the engine. On many cars, there were two fans mounted side by side to make sure that the radiator had a uniform air flow for the width of the unit. When the car was in motion, the speed of the air entering the grill was sufficient to keep the coolant at the proper temperature, so the fans were shut off. When the vehicle came to a stop, there was no natural air flow, so the fan would come on as soon as the engine reached a certain temperature. If the air conditioner was turned on, a different circuit would come into play. The reason for this is the air conditioning system always requires a good air flow through the condenser mounted in front of the radiator. If the air flow stopped, the air conditioned air coming through the dash outlets would immediately start warming up. For this reason, when the air conditioner is turned on, the fan circuit would power the fans regardless of engine temperature. If you notice that the engine temperature begins rising soon after the vehicle comes to a stop, the first thing to check is fan operation. If the fan is not turning when the engine is hot, a simple test is to turn the AC on. If the fan begins to work, suspect the temperature sensor in the fan circuit (you will need a wiring diagram for your vehicle to find it). In order to test the fan motor itself, unplug the two wire connector to the fan and connect a 12 volt source to one terminal and ground the other. (it doesnt matter which is which for this test) If the fan motor begins to turn, the motor is good. If it doesnt turn, the motor is bad and must be replaced. In order to test the system further, you will need a repair manual for the year, make and model vehicle and follow the troubleshooting charts and diagnostic procedures for your vehicle. On most systems, there will be a fan relay or fan control module that can be a trouble spot. There are a number of different control systems, each requiring a different test procedure. Without the proper repair information, you can easily do more harm than good. Cooling system power flush and refill While you can replace old coolant by draining it out and replacing it with fresh coolant, the best way to properly maintain your cooling system is to have the system power flushed. Power flushing will remove all the old coolant and pull out any sediment and scale along with it. Power flushing requires a special machine that many auto repair shops have for the purpose. The procedure requires that the thermostat is removed, the lower radiator hose is disconnected, and the flush machine is connected in line. The lower hose is connected to the machine and the other hose from the machine is connected to the radiator where the lower hose was disconnected from. Water, and sometimes, a cleaning agent is pumped through the cooling system in a reverse path from the normal coolant flow. This allows any scale to be loosened and flow out. Once clear water is coming out of the system, the hose is reconnected and a new thermostat is installed. Then the cooling system is refilled with the appropriate amount of antifreeze to bring the coolant to the proper mixture of antifreeze and water. For most vehicles and most climates, the mixture is 50 percent antifreeze and 50 percent water. In colder climates, more antifreeze is used, but must never exceed 75 percent antifreeze.Check your owners manual for the proper procedures and recommendations for your vehicle. The cooling system should be cleaned at periodic intervals to prevent the accumulation of excessive rusts and scale.Accumulated rust and scale can be loosened by a good cleaning compound.There are various types of cleaning compounds;all must be used carefully in acordance with the manufacturers instructions.冷却系统的维修与维护 一个典型的四缸汽车在高速公路上以约50英里每小时的速度行驶，在火花塞在各缸内点燃燃料推进汽车行驶过程中，发动机内每分钟将产生4000卡的爆炸能量。显然,这些爆炸产生巨大的的热量,如果不加控制,将会很快就摧毁发动机。冷却系统的目的是为了保持发动机在各种速度和操作条件下能以最有效的工作温度运作。冷却系统负责保护发动机的正常工作，使发动机使用寿命延长。事实上,一辆汽车在高速公路上行驶时，冷却系统散发的热量足以给两个普通尺寸的房子供暖!但是汽车不能没有冷却系统,换句话说，冷却系统对于汽车是非常重要的。空冷和液冷两种类型的冷却系统已经被用于四冲程的汽车发动机中。大多数的汽车发动机现在使用液体冷却，液冷系统由水泵、散热器、冷却风扇,支路恒温系统、冷冻塞、水外套等等组成。冷却系统由位于发动机缸体和发动机罩内部的通道，循环冷却液的水泵，控制冷却液温度的恒温器，降低冷却液温度的散热器以及控制系统压力的散热器盖和一些管体组成。这些管体是用来从发动机传送冷却液到散热器和汽车热系统去的，保证了在寒冷的天气汽车内部的温度。20世纪以来，冷却系统用在发动机上后，它没有改变太多。哦,当然,虽然冷却系统在工作中变得更为可靠和有效，但是基本的冷却系统仍然由冷却液组成。这些冷却液通过发动机进行循环，然后流通到外面的散热器，由通过汽车前格栅流入的空气进行冷却。现今的冷却系统必须保持发动机温度恒定，不管外面的温度是110华氏度或10零度以下。如果发动机温度过低、经济性将受损和排放率将会上升。如果温度持续过热,发动机将自我破坏。最重要的维修项目是冷却液的定期充满和替换。这个重要的原因是冷却剂中有许多添加剂,用于防止腐蚀冷却系统。在几种不同类型的金属相互作用时，这种腐蚀速度加速。规模的腐蚀最后建立并开始堵塞散热器、加热器的薄平管,最终导致发动机过热。这些在冷却剂中的防腐剂能防止这种情况的发生，但是他们有有限的寿命。经过一段时间后，锈和氧化皮限制了散热器和发动机的水外套，限制了水的循环，从而使发动机过热，此外，汽缸和散热器与发动机之间的连接器极度恶化，导致燃气泄露，很多部件关闭不严或开启不恰当，从而降低了冷却系统的有效性。一些跨国公司对这些条件进行了一系列的实验，此外，防冻剂的长处的解决方案也可以测试。全国汽车散热器服务协会(NARSA)建议，司机有七点要注意预防的东西去维护冷却系统，至少每两年检查一次。这七点旨在提醒我们确定任何部位都需要关注。它包括:1、目视检查所有的冷却系统的组成部分,包括皮带和软管2、散热器及压盖检查以推荐的系统压力水平3、检查温控器适当的开启和关闭4、压力测试,以确定所有对外冷却系统的部件无泄漏,包括散热器、水泵、发动机冷却通道,加热器软管和加热器的核心 5、内部泄漏测试来检查燃气是否泄漏到冷却系统6、发动机和风机测试正常工作7、系统能源的充满和替换。1、目视检查要是你想要检查皮带和软管部分，那么散热器软管和加热器软管是很容易检查的，仅仅只需要打开盖子然后检查就可以了。你应该确保水管无开裂或分裂和无胀形或肿胀。如果有出现问题的迹象,软管应该立即更换。不同型号，不同年份产的汽车的软管是不一样的，不能通用，除非在紧急条件和原来的软管不可使用的条件下方可使用，否则会发生预想不到的危险。确保你替换的软管符合正确的内径，不管是散热器软管或加热管,确保你更换软管的路线与原来软管的部位一样。软管安装在远离任何可能损害到它的位置上，而管夹总是使用新的。之后,你再对冷却系统的冷却剂做一个压力测试以确保没有泄漏。在大多数老旧的车辆上，水泵端由一个V形皮带或蛇形皮带驱动,还负责推动发电机、动力转向泵、空调压缩机。如果他们都磨损了，这些不同类型的皮带是容易检查和更换的。在后来的车辆上，水泵通常是由正时皮带驱动。这个皮带通常会有特定的寿命，超过此期间必须更换,以确保它没有损坏。因为正时皮带位于发动机内部，则检查时需将发动机部分拆卸，替换时将它安装在正确的间隙这是很重要的。人类用别的东西取代正时皮带有了显著意义，取代了带的同时取代了水泵。这是因为90%的工作来完成一个水泵的取代时，正时皮带已经更换。当所有东西都分开的时候，它更安全的替换了泵。2、散热器压盖压力测试散热器压盖设计的目的是为了保持冷却系统中的压力处在一个合适的最大压力，如果冷却系统的压力超过了阀门的压力,阀门顶开，冷却液释放到油箱中，一旦发动机冷却下来,在冷却系统中将产生一个负压力。产生这种情况的时候，压盖上的第二个阀将冷却剂从油箱吸收到散热器中，如果没有设计这个压盖，那么发动机很容易产生过热。散热器压盖压力测试是一个快速的方法来判断压盖是否正在正确运转。它应该能够保持其额定压力两分钟。散热器盖是相当便宜的，我建议每3年或每运行36,000公里更换一次,就当作一份额外的保险，应保证你专为你的车放一个预备。3、检查调温器适当的开启和关闭这一步是只有当你的冷却系统出现问题的时候才是必要的。恒温器的设计是用来使冷却液的温度处于一个合适的温度。启动发动机，让发动机处在一个正常的工作温度（不要让它过热），并保证调温器在发动机内部时进行测试，如果它需要较长时间才能让发动机暖和起来或者加热器开始送热风，那么调温器开关可能被卡在了。如果发动机已经暖和了,把它关掉,寻找两个散热器软管。这两条软管是从发动机连接到散热器的。小心地触碰它们（它们可能会很热）如果一个软管是热的,另一个是冷的,温控器可能被卡住。如果你怀疑温控器有问题,把它放在一壶水里，把水加热沸腾并且看温控器。你应该可以看到水沸腾时调温器开启。大多数温控器约195华氏度开启，放在水里的温度计可以确定温控器是否正常。4、压力测试,以确定所有对外冷却系统的部件无泄漏冷却系统的压力测试是一个简单的流程，用来确定泄漏的位置。这个测试只能在冷却系统足够冷却的时候进行,这样才能让您安全地移动压力盖。一旦你确定了冷却系统充满了冷却液，可将系统压力测试仪附在散热器盖上，然后这个测试器将压力泵到各个系统。在测试器上有一种计量器，在测试时显示要泵取多少的压力。你应该泵取到压力盖上的指定压力值或是生产厂家说明书上的压力值。一旦压力不符时,你就可以开始去寻找是否有泄漏。也应该检查测试器上的仪表,看看它是否失去了压力。如果压力在两分钟内下降超过几英镑,某处隐蔽的地方有可能泄漏，它并不总是很容易看到的泄露的地方。最好是能将车子举升到一定的高度，这样用个手电筒或是闪光灯就可以查看。如果加热器核心泄露,那么它并不是那么容易发现的，因为它是封闭的，不拆卸汽车的某些部件是不易检查出来的。但是一点不会弄错的标志是汽车内部冷却剂的气味，你也可以注意到挡风玻璃上有油汽残留。5、内部泄漏试验如果你冷却剂变少了,但是,目前还没有迹象显示内部泄漏,你很有可能需要检查一下汽缸垫。检验这个问题最好的办法就是做散热器燃烧泄漏试验。这里熟练的应用到一个空心盖，这是对散热器上的蒸汽进行一个化学分析的工具。将蓝色液体装在塑料容器上进行实验，如果实验过程中冷却液变黄，那么排放的废气存在散热器里。最常见的原因在于散热器里的汽缸垫坏了，更换汽缸垫需要专门拆卸发动机,可能会很昂贵。其他原因包括汽缸破裂或是堵塞,更换这两者比更换汽缸垫更让人头疼。如果一个汽缸垫坏了，需要更换首先要做的是排净发动机内的冷却液，然后拆开发动机上面的部分，以方便接近汽缸，移动缸体和缸体的朝向，彻底检查，排除不必要的损害。重新组装发动机之前，要首先清洁缸体表面的污块，以确保没有任何会干扰汽缸垫的性质。汽缸表面也应确保平坦，在某些情况下,盖帽也要检查好。汽缸垫头部位置上的垫圈对齐定位钉,否则造成堵塞。然后将汽缸放在垫片上，用表面覆有油的沉头螺栓拧紧。然后螺栓用一种特殊的扳手称为扭矩扳手扳到指定的初始扭矩，以一种特殊的顺序进行收紧，这是为了保证垫片受力均匀，以确保密封。然后以更严格的扭矩设定，重复这个过程，最后是三分之一的扭矩设定。此时，剩下的是发动机其余部分的重新组合，冷却系统充满了由防冻剂和水组成的混合物。一旦发动机被充满，技术人员将进行冷却系统压力测试，以确保没有任何泄漏。在许多发动机中，冷却液也是通过主管和进气支管进入。在进气支管还有垫片以防止在该点冷却剂的泄漏。更换进气支管垫片比更换汽缸垫片容易的多，但仍需要花几个小时或更长的时间来进行这项工作。6、发动机风扇测试冷却风扇的散热器是冷却系统运作的重要组成部分，即使当车辆行驶时尽管风扇不是真的需要。在高速公路上，当低速驾驶或驻车时它是非常重要。以前，风扇是连接到发动机的且由风扇皮带带动。风扇的转速与发动机的转速成正比。当汽车通过齿轮变速时，这种系统有时会造成过多的噪音。当发动机加速时，风扇运转的噪音还可以听见。为使环境安静点和发动机的阻力少点，开发了一种粘性风扇驱动。使当风扇不需要时，可以使风扇脱离。当计算机控制运用而生，直接安装在散热器上的电子风扇取代了这些由发动机驱动的风扇。当发动机运行到太热时，一个温度传感器可以判断而且启动风扇，要求通过散热器的空气冷却发动机。在很多车上，有两个风扇并排安装，以确保散热器有一个为单位宽度均匀的空气流。当汽车在运动时，进入散热器的空气是足够的，当保持了适当的冷却剂的温度时，风扇就关闭。当车停了下来，没有任何自然空气流通，风扇会启动直到发动机达到一个合适的温度。如果空调是开着的，那么一个不同的线路将参与工作。解释这个现象的原因是空调系统总是需要一个好的通过安装在散热器前部的冷凝器的空气流量。如果空气流通停止，那么迅速通过出口的空气将立即升温。对于这个原因，就是当空调运转，风扇线路不顾发动机的温度将向风扇提供能量。如果你注意到在汽车停下不久之后，发动机温度开始上升，要做的第一件事情就是检查你的风扇操作是否正确。当发动机很热时，如果风扇不转了，一种简单的测试方法就是打开空调。如果打开空调后风扇开始工作，那么就是在风扇线路上的温度传感器有问题（你需要一个用于你汽车的接线图）。为了能够测试风扇电动机本身问题，可以拔去两个与风扇相连接的线路接头（这个测试无关紧要），如果风扇马达开始运转，那么马达是没问题的；相反，如果风扇马达不运转，那么马达是坏的，必须要更换。为了能够更好的测试系统，你需要一本维修手册，按照那些维修图标和诊断程序来制造和模拟汽车。在大多数系统中，这里会有一个风扇或者扇状物控制那些有可能是故障点的模块。这里有许多不同的控制系统，他们每一个都需要一个不同的测试程序。没有正确的维修信息，你很容易对冷却系统的维修造成弊大于利。7、系统能源的充满和替换。当你让用过的冷却剂流出，同时用新的冷却液替代，适当维护冷却系统的最好方法是让系统能量充裕。充裕的能量将排出所有使用过的冷却液，同时冲出一些附带的沉淀物和水垢。拥有充裕的能量需要一种特殊的机器，这种机器在许多汽车维修车间就有。这个程序要求拆下恒温器，较低位置的散热器龙头要被断开，同时用来冲洗的机器要连接在一条直线上。较低位置的水龙头被连接到机器和其他来自于被连接到更低的龙头被与其分开的散热器的机器的水龙头上。水有时候作为一种清洁剂被抽取，它与正常的冷却液流向相反的方向通过冷却系统。这就使得一些水垢被溶解流出。一旦清洁的水从系统中流出，这时新的软管就被重新连接，一个新的恒温器被重新安装。到那时冷却系统就被重新填满适量的防冻剂，为了把冷却液融入适量的防冻剂和水的混合物中。对于大多数汽车和气候来说，混合物是有50%的防冻剂和50%的水组成。当气候比较冷时，会使用更多的防冻剂，但是用量最多不能超过75%。查询汽车的用户手册来找到针对你自己的车的合适的混合顺序和推荐用量。冷却系统应当周期性的清洗，为了防止上面积累过多的铁锈和水垢，一些好的洗涤剂可以溶解积累的铁锈和水垢。这里有许多种洗涤剂，这些洗涤剂都必须按照生产厂家的说明慎重使用。方案论证2.1此次离合器车型的选定设计中采用的离合器车型及车型参数如下表1： 表2-1 捷达 GTI 16V参数表汽车型号捷达 GTI 16V发动机最大功率（kw）/(r/min)102/6100总质量ma（Kg）1470发动机最大扭矩（N.m）167轮胎规格185/60VR14最高车速（km/h）205车轮半径r（mm）233.3最高转速（r/min）6650后桥主减速比3.67载重量（kg）460变速器一档传动比3.452.2确定离合器的结构型式2.2.1从动盘数的选择单片离合器：对乘用车和最大总质量小于6t的商用车而言，发动机的最大转矩一般不大，在布置尺寸容许条件下，离合器通常只设有一片从动盘。单片离合器结构简单，轴向尺寸紧凑，散热良好，维修调整方便，从动部分转动惯量小，在使用时能保证分离传递，采用轴向有弹性的从动盘可保证结合平顺。 双片离合器：双片离合器与单片离合器相比，由于摩擦面数增加一倍，因而传递转矩的能力较大；结合更为平顺、柔和；在传递相同转矩的情况下，径向尺寸较小，踏板力较小；中间压盘通风散热性差，容易引起摩擦片过热，加快其磨损甚至烧坏；分离行程较大，不易分离彻底，所以设计时在结构上必须采取相应的措施；轴向尺寸较大，结构复杂；从动部分的转动惯量较大。这种结构一般用在传递传递转矩较大且径向尺寸受到限制的场合。 多片离合器：多片离合器多为湿式，具有结合更为平顺、柔和，摩擦表面温度较低，磨损较小，使用寿命长等优点。但分离行程大，分离不彻底，轴向尺寸和从动部分转动惯量大，主要应用于最大总质量大于14t的商用车的行星齿轮变速器换挡机构中。单片离合器因为结构简单，尺寸紧凑，散热良好，维修调整方便，从动部分转动惯量小，在使用时能保证分离彻底接合平顺，所以被广泛使用于轿车和中、小型货车。综上所述，故捷达 GTI 16V从动盘数选单片离合器。2.2.2压紧弹簧布置形式的选择1）周置弹簧离合器周置弹簧离合器的压紧弹簧均采用圆柱螺旋弹簧，并均匀地布置在一个或同心的两个圆周上，其特点是结构简单、制造容易，这去广泛应用于各类汽车上。此结构的弹簧压力直接作用于压盘上，为了保证摩擦片上压力不均匀，压紧弹簧的数目要随摩擦片直径的增大而增多，而且应当是分离杠杆的倍数。因压紧弹簧直接与压盘接触，易受热回火失效。当发动机最大转速很高时，周置弹簧由于受离心力作用而向外弯曲，使弹簧压紧力显著下降，离合器传递转矩的能力也随之降低。此外，弹簧靠在其定位座上，造成接触部位严重磨损，甚至会出现弹簧断裂现象。2）中央弹簧离合器中央弹簧离合器采用一至两个圆柱螺旋弹簧或用一个圆锥弹簧作为压紧弹簧，并且布置在离合器的中心。由于可选较大的杠杆比，因此可得到足够的压紧力，且有利于减小踏板力，使操纵轻便；压紧弹簧不与压盘直接接触，不会使弹簧受热回火失效；通过调整垫片或螺纹容易实现压盘对压紧力的调整。这种结构较复杂，轴向尺寸较大，根据参考文献【4】可知中央弹簧离合器多用于发动机最大转矩大于400500Nm的商用车上，以减轻其操纵力。3）膜片弹簧离合器膜片弹簧是一种由弹簧钢制成的具有特殊结构的碟形弹簧，主要由碟簧部分和分离指部分组成。具有一系列优点：膜片弹簧具有较理想的非线性弹性特性，弹簧压力在摩擦片的允许磨损范围内基本保持不变。膜片弹簧兼起压紧弹簧和分离杠杆的作用，结构简单、紧凑，轴向尺寸小，零件数目少，质量小。高速旋转时，弹簧压紧力降低很少，性能较稳定。膜片弹簧以整个圆周与压盘接触，使压力分布均匀，摩擦片接触良好，磨损均匀。易于实现良好的通风散热，使用寿命长。膜片弹簧中心与离合器中心线重合，平衡性好。但膜片弹簧的制造工艺较复杂，制造成本较高，对材质和尺寸精度要求较高，其非线性特性在生产中不易控制，开口处容易产生裂纹，端部容易磨损。近年来，由于材料性能的提高，制造工艺和设计方法的逐步完善，膜片弹簧的制造已日趋成熟。因此，膜片弹簧离合器不仅在乘用车上被大量采用，而且在各种形式的商用车上也被广泛采用。2.2.3膜片弹簧式离合器的拉式、推式的选择分析膜片弹簧式离合器的结构形式有拉式和推式两种，推式膜片弹簧离合器按支撑结构又可分为以下三种【2】：双支撑环式单支撑环式无支撑环式1）双支撑环式图2-1 双支撑环式2）单支撑环式图2-2 单支撑环式 3）无支撑环式图2-3 无支撑环式 拉式膜片弹簧的支撑分两种，如图2-4（a）是无支撑环，（b）是单支撑环图2-4 拉式膜片弹簧的支撑类型与推式膜片弹簧离合器相比，拉式膜片弹簧离合器具有许多优点【5】：拉式膜片弹簧离合器取消了中间支承各零件，并不用支承环或只用一个支承环，使其结构更简单、紧凑，零件数目更少，质量更小；拉式膜片弹簧是以中部与鸦片相压，在同样压盘尺寸的条件下可采用直径较大的膜片弹簧，提高了压紧力的与传递转矩的能力，且并不增大踏板力，在传递相同的转矩时，可采用尺寸较小的结构；再结合或分离状态下，离合器盖的变形量小，刚度大，分离效率更高；拉式的杠杆比大于推式的杠杆比，且中间支承少，减少了摩擦损失，传动效率高，踏板操纵更轻便，拉式的踏板力比推式的一般可减少约25%30%；无论在结合状态或分离状态，拉式结构的膜片弹簧打断与离合器盖支承始终保持接触，在支承环磨损后不会形成间隙而增大踏板自由行程，不会产生冲击和噪音；使用寿命更长。但是，拉式膜片弹簧的分离指与分离轴承套筒总成嵌装在一起的，需采用专门的分离轴承，结构复杂，安装拆卸较困难。由于拉式膜片弹簧离合器综合性能优越，目前在各种汽车中的应用日趋广泛。本次设计采用双支撑环推式膜片弹簧。2.2.4压盘传力方式的选择压盘的驱动方式主要有凸块-窗孔式、传力销式、键块式和弹性传动片式等多种。前三种的共同缺点是在连接件之间都有间隙，在传动中将产生冲击和噪声，而且在零件相对滑动中有摩擦和磨损，降低了离合器的传动效率。弹性传动片式是近年来广泛采用的驱动形式，沿圆周切向布置的三组或四组薄弹簧钢带传动片两端分别与离合器盖和压盘以铆钉或螺栓联接，传动片的弹性允许其作轴向移动。当发动机驱动时，传动片受拉，当拖动发动机时，传动片受压。弹性传动片驱动的方式结构简单，压盘与飞轮的对中性能好，使用平衡性好，工作可靠，寿命长。但反向承载能力差，汽车反拖时易折断传动片，故对材料要求较高，一般采用高碳钢。故捷达 GTI 16V压盘的驱动方式选弹性传动片式。2.2.5分离杠杆、分离轴承分离杠杆的作用由膜片弹簧承担，其作用是通过分离轴承克服离合器弹簧的推力并推动压盘移动，从而使压盘与从动盘和从动盘与飞轮相互分离，截断动力的传递，分离杠杆要具有足够的强度和刚度，以承受反复作用在其上面的弯曲应力，分离轴承的作用是通过分离叉的作用使分离轴承沿变速器前端盖导向套作轴向移动，推动旋转中的膜片弹簧中部分离前端，使离合器起到分离作用。分离轴承本次设计选用的是油封轴承，它可以将润滑脂密封在轴承壳内，使用中不需要增加润滑，相比供油式轴承则需增加。2.2.6离合器的散热通风试验表明【6】，摩擦片的磨损是随压盘温度的升高而增大的，当压盘工作表面超过C时摩擦片磨损剧烈增加，正常使用条件的离合器盘，工作表面的瞬时温度一般在C以下。在特别频繁的使用下，压盘表面的瞬时温度有可能达到。过高的温度能使压盘受压变形产生裂纹和碎裂。为使摩擦表面温度不致过高，除要求压盘有足够大的质量以保证足够的热容量外，还要求散热通风好。改善离合器散热通风结构的措施有：在压盘上设散热筋，或鼓风筋；在离合器中间压盘内铸通风槽；将离合器盖和压杆制成特殊的叶轮形状，用以鼓风；在离合器外壳内装导流罩。膜片弹簧式离合器本身构造能良好实现通风散热效果，故不需作另外设置。2.2.7从动盘总成在现代汽车上一般都采用带有扭转减振器的从动盘,用以避免汽车传动系统的共振,缓和冲击,减少噪声,提高传动系统零件的寿命,改善汽车行使的舒适性,并使汽车平稳起步。从动盘主要由从动片，从动盘毂，摩擦片等组成，由下图2-5可以看出，摩擦片1，13分别用铆钉14，15铆在波形弹簧片上，而后者又和从动片铆在一起。从动片5用限位销7和减振12铆在一起。这样，摩擦片，从动片和减振盘三者就被连在一起了。在从动片5和减振盘12上圆周切线方向开有6个均布的长方形窗孔，在在从动片 和减振盘之间的从动盘毂8法兰上也开有同样数目的从动片窗孔，在这些窗孔中装有减振弹簧11，以便三者弹性的连接起来。在从动片和减振盘的窗孔上都制有翻边，这样可以防止弹簧滑脱出来。在从动片和从动盘毂之间还装有减振摩擦片6，9。当系统发生扭转振动时，从动片及减振盘相对从动盘毂发生来回转动，系统的扭转能量会很快被减振摩擦片的摩擦所吸收。图2-5 带扭转减振器的从动盘1，13摩擦片；2，14，15铆钉；3波形弹簧片；4平衡块；5从动片；6，9减振摩擦；7限位销；8从动盘毂；10调整垫11减振弹簧；12减振盘1）摩擦片要求摩擦片的工作环境是比较恶劣的，为了保证它能长期稳定的工作，根据汽车的使用条件，摩擦片性能应满足一下几个方面的要求：摩擦因数较高且较稳定，工作温度、单位压力、滑磨速度的变化对其影响要小。有足够的机械强度与耐磨性。密度要小，以减小从动盘转动惯量。热稳定性好，在高温下分离出的粘合剂少，无味，不易烧焦。磨合性能好，不致刮伤飞轮和压盘表面。接合时应平顺而不产生“咬合”或“抖动”现象。长期停放后，摩擦面间不发生“粘着”现象。 离合器摩擦片所用的材料有石棉基摩擦材料、粉末冶金摩擦材料和金属陶瓷、摩擦材料。石棉基摩擦材料具有摩擦因数较高(大约为03045)2、密度较小、制造容易、价格低廉等优点。但它性能不够稳定，摩擦因数受工作温度、单位压力、滑磨速度的影响大，目前主要应用于中、轻型货车中。由于石棉在生产和使用过程中对环境有污染，对人体有害，所以现在正以玻璃纤维、金属纤维等来替代石棉纤维。粉末冶金和金属陶瓷摩擦材料具有传热性好、热稳定性与耐磨性好、摩擦因数较高且稳定、能承受的单位压力较高以及寿命较长等优点，但价格较贵，密度较大，接合平顺性较差，主要用于重型汽车上。 摩擦片与从动片的连接方式有铆接和粘接两种。铆接方式连接可靠，更换摩擦片方便，适宜从动片上装波形片，但其摩擦面积利用率小，使用寿命短。粘接方式可增大实际摩擦面积，摩擦片厚度利用率高，具有较高的抗离心力和切向力的能力，但更换摩擦片困难，且使从动盘难以装波形片，无轴向弹性，可靠性低。 本设计中，选取的是石棉合成物制成的摩擦材料。2）从动盘的轴向弹性从动盘的轴向弹性可改善离合器性能，使离合器接合柔和，摩擦面接触均匀，磨损较小。为使从动盘有轴向弹性，单独制造扇形波状弹簧与从动钢片铆接【2】。波状弹簧可用比钢片轻薄的材料制造，轴向弹性较好，转动惯量小，适宜高速旋转，且弹簧对置分布，弹性好。因此设计中选用此类弹簧。图2-6 波形弹簧 3）扭转减振器扭转减振器主要由弹性元件(减振弹簧或橡胶)和阻尼元件(阻尼片)等组成。弹性元件的主要作用是降低传动系的首端扭转刚度，从而降低传动系扭转系统的某阶(通常为三阶)固有频率，改变系统的固有振型，使之尽可能避开由发动机转矩主谐量激励引起的共振；阻尼元件的主要作用是有效地耗散振动能量。所以，扭转减振器具有如下功能：降低发动机曲轴与传动系接合部分的扭转刚度，调谐传动系扭振固有频率增加传动系扭振阻尼，抑制扭转共振响应振幅，并衰减因冲击而产生的瞬态扭振。)控制动力传动系总成怠速时离合器与变速器轴系的扭振，消减变速器怠速噪声和主减速器与变速器的扭振与噪声。缓和非稳定工况下传动系的扭转冲击载荷和改善离合器的接合平顺性。2.3 离合器结构设计的要点在进行离合器的具体设计时，首先应保证传递发动机最大扭矩为前提，然后满足下列条件【7】:1）如前所述，扇形波状弹簧对置分布铆接在从动钢片上，并在从动盘上设置扭转减震器保证离合器接合柔和，摩擦片制成一定锥度（从动盘锥形量约为0.5mm）使其大端面向飞轮，这样从动盘毂在从动轴（即变速器第一轴）花键上易于滑动，有利于离合器彻底分离。2）离合器主动部分与从动部分的连接和支撑形式，离合器的主动部分包括飞轮，离合器盖与他们一起转动并能轴向移动的压盘，压盘通过钢片与离合器盖相连，离合器从动部分有从动盘，从动轴，从动轴装在飞轮与压盘之间，可在从动轴花键上滑动，设计时把离合器从动轴的前轴承安装在发动机曲轴的中心孔内。3）离合器从动轴的轴向定位及轴承润滑，离合器从动轴在安装后应保持轴向定位，在拆卸时便于离合器中抽出来。因此，设计时使从动轴前轴承外圆与飞轮为过渡配合，而前轴承内圈与从动轴为间隙配合，离合器的从动轴轴向定位是靠从动轴后轴承来保证的。离合器分离轴承靠注入黄油润滑的，而从动轴前轴承靠油杯定期注入润滑。 为防止润滑油流到摩擦衬面，造成离合器打滑，除在轴承处安有自紧油封外，还在飞轮上开泄油孔。4）离合器运动零件的限位，离合器处于接合时为使压盘与摩擦片很好接合，应使分离弹簧与分离轴承之间保持一定间隙，这是分离轴承回位弹簧加以保证。分离时，应对踏板的最大行程加以限制。2.4 离合器主要零件的设计2.4.1从动盘总成设计从动盘总成由摩擦片，从动片，减震器和从动盘穀等组成。它虽然对离合器工作性能影响很大的构件，但是其工作寿命薄弱，因此在结构和材料上的选择是设计的重点。从动盘总成应满足如下设计要求：为了减少变速器换档时齿轮间的冲击，从动盘的转动惯量应尽可能小为了保证汽车平稳起步、摩擦面片上的压力分布均匀等从动盘应具有轴向弹性为了避免传动系的扭转共振以及缓和冲击载荷，从动盘中应装有扭转减 振器要有足够的抗爆裂强度。下面分别叙述有关从动片、从动盘毂和摩擦片等零件的结构选型和设计。1）从动片设计从动片时，要尽量减轻其重量，并使质量的分布尽可能靠近旋转中心，以获得小的转动惯量。这是因为汽车在行驶中进行换档时，首先要分离离合器，从动盘的转速必然要在离合器换档的过程中发生变化，或是增速（由高档换为低档）或是降速（由低档换为高档）。离合器的从动盘转速的变化将引起惯性力，而使变速器换档齿轮之间产生冲击或使变速器中的同步装置加速磨损。惯性力的大小与冲动盘的转动惯量成正比，因此为了见效转动惯量，从动片都做的比较薄，通常是用1.32.0厚的薄钢板冲压而成2,为了进一步减小从动片的转动惯量,有时将从动片外缘的盘形部分磨至0.651.0,使其质量更加靠近旋转中心2。为了使离合器结合平顺，保证汽车平稳起步，单片离合器的从动片一般都作成具有轴向弹性的结构，这样，在离合器的结合过程中，主动盘和从动盘之间的压力是逐渐增加的，从而保证离合器所传递的力矩是缓和增长的。此外，弹性从动片还使压力的分布比较均匀，改善表面的接触，有利于摩擦片的磨损。 具有轴向弹性的的传动片有以下三种形式：整体式的弹性从动片，分开式的弹性从动片、及组合式弹性从动片。在本设计中，选择的是分开式的弹性从动片，从动片与波形弹簧分开做成两件，然后用铆钉铆在一起。2）从动盘毂 从动盘毂是离合器中承受载荷最大的零件，它几乎承受发动机传来的全部转矩。它一般采用齿侧对的矩形花键安装在变速器的第一轴上，花键的尺寸可根据摩擦片的外径D与发动机的最大转矩Temax按国标GB114474选取【8】。从动盘的轴向长度不宜过小，以免在花键轴上滑动时产生偏斜而使分离不彻底
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