In recent years, turbochargers have been widely used in diesel vehicles. At the same time of rapid development, some problems have yet to be solved. The reporter interviewed people in the industry on this topic. Experts and scholars in the industry analyzed that the problems currently faced by domestic turbocharger industry are concentrated in three aspects: First, emission upgrades put forward new technical requirements for turbochargers; second, supercharger is in the process of production and use. The existing problems include abnormal noise, oil leakage, and fracture. Third, the protection of intellectual property rights involved in the development of new products has not received sufficient attention.
Emissions upgrades make new demands
Carbon monoxide, hydrocarbons, nitrogen oxides and solid particles are the most polluting substances in diesel exhaust. They are not only harmful to the human body, but also affect the atmosphere. As people's awareness of environmental protection continues to increase, the requirements for emissions from relevant laws and regulations are increasingly strict.
In order to control the pollution of exhaust gas, many countries have formulated corresponding environmental protection regulations and technical supervision standards for controlling pollutant discharge. China also enforced the “Exhaust Pollutant Limits and Test Methods for Vehicles with Compression Ignition Engines and Compression Ignition Engines (GB17691-1999)†and “Visible Pollutants for Compression Ignition Engines and Vehicles with Compression Ignition Engines†Limits and test methods (GB3847-1999) and Other discharge standards.
Seeing that the global energy crisis is becoming increasingly serious, turbocharging technology has become an effective and necessary technology to increase power and torque, reduce fuel consumption, and meet emission standards. According to reports, the turbocharger can meet the requirements of the emission regulations from the State II to the State III, but the existing supercharger technology cannot easily meet the national IV or even higher emission standards. Chen Chaoming of Yuchai Technology Center stated that upgrading to China IV can be achieved through different technical routes: First, a supercharger with bypass valve, VNT (variable section supercharger) or two-stage supercharging. Second, SCR (Selective Catalytic Redox) is used. This can reduce NOx, and particulate emissions can be achieved through in-house purification. Third, the EGR EOC (oxidation catalyst) is cooled.
Industry experts agree that the National IV emission regulations are a great challenge to the turbocharger industry in China and the entire internal combustion engine industry. VNT or two-stage booster systems are complex and it takes time to overcome these difficulties.
Abnormal sound, oil leakage and fracture into industrial problems
In the interview, the reporter learned that domestic turbochargers are susceptible to problems such as abnormal noise, oil leakage, and fracture during use. This is a problem that has not been solved in the industry.
Professor Lu Jiaxiang of the School of Energy and Power Engineering of Shandong University and the State Council's special allowance recipient believes that there are several reasons for the turbocharger oil spill: First, there is a pressure difference. There is a large pressure difference between the pressure of the compressor and the turbine and the oil pressure, causing oil leakage. This is the root cause of the oil spill. Second, it relates to the working conditions of the rotor and the housing. There is a gap between the moving rotor and the stationary housing. If the gap is unreasonable, it will leak oil. Third, poor production consistency. At present, the test conditions of various manufacturers are limited. The dimensions and tolerances on the drawings are inconsistent with the actually processed products, leading to partial turbocharger leakage.
Beijing University of Technology professor Ma Chaochen believes that supercharger leakage oil should be strictly controlled. He explained: "Oil consumption is one of the main sources of particulates. Turbocharger leakage is common, there are design and manufacturing reasons, there are reasons for use. We need to develop oil leakage test evaluation methods and develop relevant standards."
The exhaust turbocharger has a poor working environment. Turbocharger impeller rotor speed up to 100000r/min or so. With such a high rotational speed, high demands are placed on bearings and compressor impellers. The strength of the bearing should be ensured to prevent it from breaking due to fatigue failure due to high-speed rotation.
Abnormal sound is also a typical problem. An industry expert stated that the method of measuring abnormal sound is not perfect now and cannot form an objective judgment. According to the tester's on-site observation, abnormal noise has a weak influence on power and fuel consumption, but it will affect dynamic performance when serious. Abnormal noise is related to the working status of the turbocharger and the surrounding environment. The production conditions are not good, resulting in a blade thickness error of up to 20%, may cause abnormal sound. In addition, the floating bearing gap is also one of the causes of abnormal noise.
Intellectual property should be valued
In recent years, the automotive industry has developed rapidly and many new products and technologies have been widely used. However, there are still many problems in the protection of intellectual property in China. In some cases, the relevant laws and regulations on the protection of intellectual property rights in China do not have a corresponding effect in practice.
Industry experts told reporters that we must pay special attention to the protection of intellectual property rights. As far as turbochargers are concerned, the current problem facing the industry is the upgrading of the National III to National IV emission standards. This requires the development of VNT or two-stage turbocharging technology. However, foreign technology in this area has matured, and they applied for a patent on these technologies.
The research and development of domestic enterprises will inevitably bear the name of infringement in terms of design ideas or methods. This kind of thing is not uncommon. Therefore, some companies in China are now applying for VNT patents. In addition, there are expert groups to formulate national standards such as nozzle rings. Intellectual property protection is a long-term and long-term task. We need to make great efforts.
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