I. Explanation of Nouns
1. The advantages of diesel engine are high power and good economic performance. The working process of diesel engine has many similarities with that of gasoline engine, and each working cycle has to go through four strokes: intake, compression, work and exhaust. However, because the fuel used by diesel engine is diesel, its viscosity is higher than that of gasoline and it is not easy to evaporate, but its spontaneous combustion temperature is lower than that of gasoline, so the formation and ignition mode of combustible mixture are different from that of gasoline engine. The main difference is that the mixture in the cylinder of diesel engine is compression ignition, not ignition. When the diesel engine is working, air enters the cylinder. When the air in the cylinder is compressed to the end, the temperature can reach 500-700℃ and the pressure can reach 40-50 atmospheres. When the piston approaches the top dead center, the high-pressure pump on the engine injects diesel into the cylinder at high pressure, and the diesel forms fine oil particles, which are mixed with high-pressure and high-temperature air. The diesel mixture burns itself and expands violently, generating explosive force and pushing the piston to do work downward. At this time, the temperature can reach 65,438+0,900-2,000℃ and the pressure can reach 60-65,438+0,000 atmospheric pressure, which generates a lot of power.
2. The advantages of diesel engine in energy saving and carbon dioxide emission are irreplaceable by all heat engines including gasoline engine. Therefore, the emission of advanced small high-speed diesel engine has reached the Euro III standard, and it has become a "green engine", and now it has become the power device of many new cars in Europe and America.
Second, maintenance
1. In order to prolong the service life of diesel engine, it is necessary to strengthen the maintenance of air filter, lubricating oil filter and fuel filter and give full play to their functions.
2. When installing the air filter, don't miss, reverse or misplace each sealing washer and rubber connecting pipe, and ensure the tightness of each press-fitting place. The used paper dust cup air filter should be cleaned every 50- 100 hours/time, and the surface dust can be brushed off with a soft brush. If the working time exceeds 500 hours or it is damaged, it should be replaced in time. Use an oil-bath air filter, clean the filter element with clean diesel oil every 100-200 hours, and replace the lubricating oil in it. If the filter element is damaged, it needs to be replaced immediately, and pay attention to adding lubricating oil according to regulations during use.
3. If the lubricating oil filter is not maintained in time in use, the filter element is blocked, the lubricating oil pressure rises, the safety valve opens, and the lubricating oil directly flows into the main oil circuit, which will aggravate the wear of the lubricating surface and affect the service life of the diesel engine. Therefore, the lubricating oil filter should be cleaned every 180-200 hours 1 time. If it is damaged, it should be replaced immediately to prevent impurities from entering the lubricated surface. When the diesel engine is used in different seasons, the crankcase and all lubricating surfaces should also be cleaned. The method is to mix lubricating oil, kerosene and diesel oil to make washing oil, and then add it after the lubricating oil is released and cleaned. Then, the diesel engine runs at low speed for 3-5 minutes, then the washing oil is discharged and new lubricating oil is added.
4. Various fuel filters in the fuel supply system should be cleaned 1 time or replaced every 100-200 hours, and the fuel tank and oil pipeline should be thoroughly cleaned. Especially for the electronically controlled rail system, due to high-pressure precise injection, the fuel system has high coupling precision and small fit clearance, which puts forward higher requirements for the filtration efficiency and water separation efficiency of the fuel filter. At present, two-stage filtration system, one-stage oil-water separator and one-stage diesel fine filter are used. It is required that the water separation efficiency is greater than 95%, the particle filtration efficiency is 3-5 microns, and the filtration efficiency is greater than 98.6%. At present, the companies that meet the performance requirements are mainly European and American companies, such as Bosch, Lubo Discoverer, Fleetguard, Mann-hummel, Pike, etc., and also in China. Special care should be taken during routine maintenance. If any abnormality is found or the mileage and time meet the requirements of the engine, it needs to be replaced in time. When changing oil during seasonal change, all parts of the whole oil supply system should be cleaned. The diesel oil used should meet the seasonal requirements and should be precipitated and purified for 48 hours.