汽车方面论文英语翻译.doc

Thesis: Automotive Engine Cooling System Maintenance Introduction: If an engine cooling system repair rate has been high, often caused by other components of the engine damage, especially with the increase in vehicle mileage, the work efficiency of the cooling system of gradual decline in the overall ability of the engine greater impact, the importance of the cooling system is maintenance work in the engine room temperature, just like the skin and sweat glands of the body, if one day, the bodys sweat glands are not working properly, the bodys heat will not be able to disperse, ranging from produce heat stroke, re- then the shock. The role and composition of the first chapter of the cooling system The function of the cooling system is taken away by the engine due to combustion heat generated by the engine to remain within the normal operating temperature range. Engine in accordance with the manner of cooling can be divided into air-cooled engines and water-cooled engines, air-cooled engines rely on engine-driven fans and air flow to cool the engine when the vehicle; water-cooled engine is cooled by cooling water circulating in the engine to engine. Regardless of mining the way in which cooling, the normal cooling system must ensure that the engine in all sorts of driving environments are not caused by overheating. The water cooling system is generally composed by the radiator, thermostat, water pump, waterway, fan. The radiator is responsible for circulating water cooling, water pipes and heat sinks use of aluminum, aluminum pipes made of flat shape, the heat sink with a corrugated, focusing on the thermal performance, installation direction perpendicular to the direction of air flow, as far as possible do drag is small, higher cooling efficiency. The radiator is divided into horizontal flow and vertical flow of two types of air conditioning condenser is usually its fit together. Water pump and thermostat. Engine by the coolant loop, the components of forced coolant circulation pump, driven by the crankshaft belt, promote the coolant circulating throughout the system. The most advanced water pump is electric water pump on a new generation of BMW straight six engine, that is precisely control the pump speed, and effectively reduce the loss of output power. These coolant cooling the engine, according to the work of the engine at any time adjust. When the engine temperature is low, the coolant within the engine itself, small cycles, when the engine temperature is high, the coolant in the engine - between radiator bigger cycle. Parts of the coolant to do different cycle control is the thermostat. Thermostat can be seen as a valve, the principle is to use with the temperature expansion of the material (paraffin or ether of the class materials) and a switch valve, expansion valve to open the top, when the high water temperature materials and coolant for large cycle, when the water temperature is low shrinkage close the valve, coolant small cycles. The flow of air In order to improve the cooling capacity of the radiator, fan forced ventilation is installed behind the radiator. Car radiator fan is directly driven by the crankshaft belt, engine to start it is necessary to transfer, can not, as the engine temperature changes, in order to adjust the cooling power of the radiator in the radiator installed on the activities of one hundred windows to control wind to enter. The now widespread use of fan electromagnetic clutch or electronic fan clutch and shaft separation, when the water temperature is relatively low, the fan does not move power from the temperature sensor when the water temperature is relatively high, the clutch shaft joint, turn the fan. Similarly, electronic fan directly by the motor driven by the temperature sensor to control the motor operation. These two forms of the radiator fan running in fact by the temperature sensor control. Radiator The heat sink doubles as a storage and cooling effect, and then on top of this is also equipped with the expansion tank. Rely solely on the heat sink has several drawbacks,one is the side of the pump suction pressure is low and easy boiling, water pump impeller is prone to cavitation; two gas-water separator to produce air resistance; high temperature coolant is easy to boiling. Designers to install the expansion tank, its up and down two pipes and the radiator upper and the pump inlet connection, to prevent the generation of the above problems. Cooling medium Although we call for the water-cooled cooling medium is not pure water, but a mixture of water, antifreeze, and various specialized use of preservatives, also known as the coolant. Coolant antifreeze content of 30% to 50%, the freezing point of water damage to the engine to prevent freezing at low temperatures. The entire cooling system is not connected with the atmosphere, equivalent to the role of a pressure cooker, radiator caps is the equivalent of a high pressure valve, under normal circumstances, the car coolant allows the operating temperature of up to 120 degrees Celsius. Construction and maintenance of the second chapter of the cooling system Automotive engine cooling system is important to maintain the normal work of the engine components, engine cooling system repair rate is high, can cause damage to other parts of the engine, the engines overall ability to work affected, therefore, the maintenance of automotive engine cooling system and maintenance is particularly important, then, how to make car engine cooling system to keep in good condition? Chi Pu-resistant automotive beauty conservation experts tell us, correct heap protect the engine cooling system, and should first understand the main components of the commonly used water-cooled engine: First, the coolant, the coolant of clean soft water, not water as a coolant, the more delicate of the car the higher the water quality requirements. For example, clear spring water, although clear, looks clean, but contain a large number of mineral springs, to join the engine cooling system, it will produce large amounts of scale, play the normal role of cooling system, visible coolant The quality of the water quality is very important, commonly used glycol coolant is to add antifreeze (ethylene glycol) in demineralized water in proportion, together with the amount of metal corrosion inhibitor, scale inhibitor agent additive to reconcile science to reach the winter frost, summer anti-boil, and can corrosion resistant, waterproof scale role. 1, the antifreeze. Coolant prepared using ethylene glycol as low as -70environment. Coolant on the market, ethylene glycol concentration is generally maintained between 33 to 50 percent, that is, between the freezing point of -20 -45 often based on the actual needs of different geographical reasonable choice to meet the requirements. 2, anti-boil. Ethylene glycol added to the water will change the boiling point of the coolant. The higher the concentration of ethylene glycol coolant boiling point higher coolant -20 boiling point of 104.5, -50, boiling point 108.5 .If the cooling system pressure cap, coolant boiling point will be higher, even during the hot summer, can effectively prevent the coolant boil. 3, anti-corrosion. Coolant main function is to prevent corrosion. Corrosion is a chemical, electrochemical, and erosion and gradually destroy the metal surface in the cooling system can make serious wall perforation of the cooling system, causing coolant leakage, causing engine damage. Deionized water and appropriate additives to prevent the emergence of a variety of corrosion. 4, anti-rust. The corrosion is caused by oxidation within the cooling system. Heat and moisture accelerate the corrosion process. Corrosion residue left behind can clog the cooling system, accelerated wear and reduce the efficiency of the thermal conductivity. Additives in the coolant helps prevent corrosion in the cooling system channels. 5, anti-scaling. Water contained in a variety of impurities, including metal ions, inorganic salts, etc., determine the scaling and precipitation formation, and will greatly reduce the thermal efficiency of the cooling system and engine, in many cases will cause serious damage. Coolant deionized water to avoid fouling and precipitation formation, thereby protecting the engine. Second, the cylinder of water, it is equivalent to the engine combustion chamber surrounding waterways, when the engine produces a lot of heat, the cylinder water jacket will play a cooling role in the engine water and oil pipe split, noninterference in each other, if we find coolant, oil, and waterways and oil perforated Once that happens, the water temperature of the water temperature meter will soar, then we must take timely measures. third, Radiator and cooling fan, cooling water tank from the outside seemed to be cellular, made up of such a shape in order to increase the cooling water tank area, to enhance the cooling effect; cooling fan installed in the front, there are also installed in the side. vehicles in high speed process, the cooling fan to the outside air to attract come in, use of natural wind, play a role in cooling. The cooling system and air conditioning condenser fan is a fan of DC permanent magnet motor, control, temperature control switch mounted on the radiator when the coolant in the radiator temperature dropped to 93 -98 , fan stall. Electric fan power from the ignition switch control, turn off the engine, radiator liquid temperature above 88 -93 , electric fan operation is not normal. The fan still turn if less than 88, it is not normal; when the temperature is above 98, does not turn it is not normal. When the temperature is higher than 105, the high temperature part of the temperature control switch connected to the power-on motor high-speed operation; when the temperature reaches 120, cooling water temperature is too high, the alarm indicator light flashes the fan failure or coolant . Such as motor fan does not turn, inspect and replace the fuse or repair the thermostat switch, if necessary, and then view the fan for damage. Fourth, the cooling water pump and thermostat, coolant flow in the cooling system, and rely mainly on the cooling water pump power; the thermostat is capable of sensing engine operating temperature, low temperature, which seal the water jacket in the water, so that it flow in the water comprising, when a certain temperature is reached and then open and let the water through the cooling water tank, play a cooling role. Worthy of note here is not to remove the thermostat, otherwise it will cause the engine is too cold and difficult to start. Proper maintenance of the engine cooling system should be aware of the often several cooling system failure: 1, due to poor water quality of the coolant tank, often rust, dirt and scale, they accumulate in the tank channel junction at the corners, impede water flow, resulting in adverse heat, if this happens, should be promptly cleaned. daily adding water, as far as possible and clean soft water, descaling rust-proof liquid, conservation would be better, to recommend the Chi Pu-resistant S-510 Cooling fast detergents, it can be quickly dissolved in the cooling system scale, sludge and rust leather, restore the function of the cooling system, coolant circulation to prevent overheating, boil and caused damage to the engine and power; In addition, Chi Pu-resistant S-520 cooling system anti-rust lubricant is a good product, it can prevent the cooling system rust and corrosion, inhibit scale generation, lubrication pump, thermostat, eliminating the pump abnormal noise, protection of copper, aluminum, tin and other metal parts to prolong tank life, to prevent the tank boil The engine work at normal temperature. Clear of Cooling scale measures maintenance: can be 2% caustic soda solution added to the cooling system, making the car driving all released one day after, and then rinse; then the same caustic soda solution, put the net for a day, and finally washed with water net. Can also fill with water in the cooling system from the expansion tank outlet add 1kg of soda, car driving day to put the net after the engine running at low speed and continue adding water from the filler, you can completely remove scale. 2, leaking fluid, may have a leak, the water in the cylinder water jacket in the event of leakage, Water temperature gauge, water temperature will rise sharply, such a situation, you must promptly take the necessary measures in order to avoid not the necessary trouble, here to introduce to you Chi Pu-resistant S-530 Cooling stanch agent for repair and protective effect of the cooling system is equivalent to 99 super repair agent and S-201, engine repair and protection, to prevent the leakage of the tank, radiator, water pump, thermostat and other parts are unique, it can be used with any coolant blending, and can slow down the cooling system of impurities produce. In general, the cooling system failure, can not be enumerated. Under normal circumstances, you owners should follow such a principle, vehicles, each traveling 1,000 km, it should look at the work of the engine. In addition, the car just stop, can not immediately open the radiator cap in order to avoid burns. Fifth, Cooling System Works The function of the cooling system is to make the engine in any condition to an appropriate degree of cooling, thereby maintaining the appropriate temperature (coolant temperature) work. Chapter Three of the cooling system is characterized by The role of the traditional cooling system is to reliably protect the engine, but should also have a role to improve fuel economy and lower emissions. To this end, the cooling system should consider the following factors: internal engine friction losses; the power of the cooling system pump; combustion boundary conditions, such as the combustion chamber temperature, Charge density, charge and temperature. Advanced cooling system uses a systematic, modular design approach, and consider each of the influencing factors, so that the cooling system to ensure that the engine work properly, but also improves engine efficiency and reduce emissions. 3.1 the temperature set point The limits of the engine operating temperature depends on the maximum temperature of the surrounding area of the exhaust valve. Ideally, the metal temperature than the coolant temperature controlled cooling system, so as to better protect the engine. Cooling temperature set by the cooling system is based on full load cooling rate basis, therefore, the engine and cooling system at part load in less than ideal, such as urban driving and low speed will result in high fuel consumption and emissions . By changing the set point of the coolant temperature can improve the performance of the engine and cooling system at part load. According to the temperature limit of the exhaust valve around the area, you can increase or reduce the set point of the metal temperature of the cooling fluid. Increase or decrease the temperature points have their own characteristics, depending on the desired purpose. 3.2 to raise the temperature setpoint Increase the temperature set point is a popular method. Increase in temperature has many advantages, it directly affects the formation of engine wear and tear and the effect of the cooling system and engine emissions. Operating temperature will increase the engine oil temperature, reducing engine friction and wear, lower engine fuel consumption. Studies have shown that the engine operating temperature on the friction loss. Coolant discharge temperature to 150, so that the cylinder temperature to 195, fuel consumption decreased by 4% -6%. Coolant temperature will be maintained in the range of 90-115 , so the engine oil temperature of 140, the fuel consumption at part load decreased by 10%. Increase temperature significantly affect the performance of the cooling system. Improve coolant or metal temperature will improve the delivery of the engine and the cooling gas heat transfer effect, lower coolant flow rate, reducing the power rating of the pump, thereby reducing the power consumption of the engine. In addition, can be used in different ways, to further reduce the coolant flow rate. 3.3 to lower the temperature setpoint Reduce the operating temperature of the cooling system can improve the engine volumetric efficiency, reduce intake air temperature. This combustion process, fuel efficiency and emissions favorable. The lower the temperature set point can save the engine operating costs and increase component life. Studies have shown that if the cylinder head temperature is reduced to 50, ignition advance angle is 3in advance A not occurred knock 2% volumetric efficiency, improved engine operating characteristics, helps to optimize the compression ratio and parameter selection to obtain more good fuel efficiency and emissions performance. Chapter Four cooling system overhaul Common cause of engine overheating reasons: the cooling air flow reduction (such as radiators blocking, etc.); cooling fan does not work; low speed uphill, the ambient temperature is too high; V-belt is too loose, turn the efficiency is poor; cylinder scale. thermostat failure, pump damage, thermal switch failure. In order to prevent the coolant temperature is too high, must be maintained in the use of the radiator and water jacket cleaning, cooling fluid in sufficient quantity, the fan belt tensioner appropriate to prevent the engine load of long working hours. You must pay attention to the following points: Keep the cooling system (radiator in particular) external and internal cleaning is an important condition for improv