There is no longer a black tail passenger car diesel engine efficient environmental protection

At this stage, passenger car diesel technology has reached the requirements of clean energy, diesel engine has long been not a humming "black tail" image.

Low-speed high torque and high-speed high-power are its characteristics Compared with gasoline engines, due to the relationship between the structure and working principle of diesel engines, there will be some relatively unique technical characteristics. Some of these technical characteristics become the selling point of diesel engines, and some It also limits the application of diesel engines.

Professor Liu Dong of the Beijing Automotive Institute told the reporter: “The current diesel engines mostly use turbocharging technology, so their torque output characteristics are similar to those of the gasoline booster models. The maximum torque can be output at a lower speed and can maintain a broad range. Torque peak output curve platform. The current new technology diesel engine also has a great increase in power, and it also performs very well in high-speed power."

Professor Liu said: "Because of the higher combustion efficiency of diesel engines, the fuel economy of diesel engines is also very prominent. Nowadays, diesel engines have greatly improved in terms of noise, and there is no obvious difference from gasoline engines of the same class. In addition, diesel The engine is compression-ignited, the circuit is simpler, and there is no ignition system, so the failure rate is even lower."

High pressure common rail direct injection, turbocharged intercooling is the mainstream technology At present, the mainstream diesel engine technology on the market are mainly high pressure common rail direct injection and turbocharged intercooling. Hong Zhiping (Weibo), a senior engineer of FAW-Volkswagen, told the reporter: "Different from the petrol engine igniting the fuel mixture, the diesel engine is compressed by heating the intake air and mixing it with the diesel spray to form a combustion system. Therefore, an effective set has been achieved. The fuel injection system is very critical for diesel engines.Because the compression ratio of the diesel engine is large, the pressure inside the cylinder is very large. To form a uniform oil mist, a high injection pressure is also required. Before that, diesel engines used mechanical injection devices. Now mainly electronically controlled high-pressure common-rail injections are used, and high-pressure oil pumps pressurize the nozzles with solenoid valves to control the timing of fuel injection and fuel injection to achieve precise and efficient fuel injection control.” “The current mainstream diesel engines are Turbocharging is used to improve the performance of the engine.The turbocharger of the diesel engine also extends the technology of variable section turbine, intercooling, and exhaust gas circulation, in which the variable section turbine changes the effective cross-sectional area of ​​the turbine under different operating conditions. Achieve better output of engine power performance at low speeds and high speeds; Improve the thermal efficiency of the engine, reducing the operating temperature of the turbine and to prolong its service life, in addition to be improved exhaust gas recirculation diesel engine waste discharge. "

Exhaust gas aftertreatment and particulate recovery allow cleaner emissions With the current development of diesel technology, in order to meet higher emission standards, in addition to the exhaust gas recycling technology, diesel engines are also equipped with particulate filters and have exhaust gas aftertreatment. Ability to further reduce the emission of pollutants such as nitrogen oxides and respirable particulate matter.

For the future development trend of diesel engines, Liu Dong believes that: "Diesel engines must raise their emission standards on the one hand to meet the increasingly stringent environmental protection requirements, and on the other hand they should also be more widely used in the current popular hybrid technology, while small The superior economy of the displacement diesel engine is also expected to increase the efficiency of the hybrid system."