The Research Of Method For Diesel Engine' Cold Starting

As the most effective thermodynamic engine, the diesel engine is widely used in various fields of national economy and military equipment. For diesel engine the ability of cold starting is one of the most important performance targets. It not only is related to whole diesel engine's efficiency, but also affects exhaust target, further more its applied time is limited. If the diesel engine can't start or start reliably under low temperature, it will not only debase the application efficiency, but also bring too much inconvenience to user, further more it may delay opportunity to bring up heavy losses. Especially, the cold starting ability of diesel engine for special vehicles (such as army vehicles fire engines and so on) is required more strictly. So the reliability of diesel engines' cold starting must be solved. Domestic and foreign specialists have made deeply research on the subject. The results show that diesel engines' starting must be based on three conditions: 1) There exists curtain amount of blended ignitable gas made up of fuel and air. 2) The ignitable gas must arrive at certain temperature. 3) The firing temperature must be kept for certain time. Accordingly, many ways of improving the ability of cold starting are brought forward ( such as increasing compression ratio and improving admission temperature setting electric heating stoppe improving cetane value and using additive adding assistant fuel and so on ), and many experiments are carried out for the research. The result show that increasing compression ratio and promoting admission temperature is the best effective measure for improving the cold starting ability of diesel engine and decreasing harmful exhaust at starting moment. But the traditional methods of changing compression ratio are structurally complicated, so it is difficult to carry out. Meanwhile the change can increase diesel engine' mechanical burden and heat-burden, besides it can make diesel engine work roughly and bring other bad effects. Therefore, a new kind of aided device is invented. The workingprocess is when diesel engine obtains needed rotational speed andappropriate turning angle of crankshaft at starting, certain lubricating oil is injected into the cylinder to increase compression ratio. The device sufficiently utilizes the effects of high compression ratio to diesel engine's cold starting, meanwhile it can promote the cylinder's airproof capability and decrease blow-by, so it realizes the purpose of improving the capability of diesel engine's cold starting. The device doesn't change diesel engine's basic structure, and it works in one work circulation during the staring process, so it makes no effects on diesel engine's working states after staring. The paper makes emphases on analyzing how to calculate the quantity of lubricating oil needed to inject into cylinder, the effects that bring forth, and the control system's working principal, structure characters and the makeup of software and hardware.