With the formal entry into force of the international "Kyoto Protocol," the European automotive industry hopes to use the "Euro 5" and the subsequent "Euro 6" to use the European diesel sprinkler's mature technologies in energy conservation and pollution control to revitalize the European auto industry and make it Maintain the world's leading position and completely monopolize the scientific and technological advancement of environmentally friendly and energy-saving engines. China is a signatory to the "Kyoto Protocol." Regardless of whether it is political or political considerations, the Chinese government must fulfill its commitment to the world and use half of the time to finish the European Union (plus the United States and Japan) from Europe. Emission Standards I to V or Euro VI's more than 20 years of implementation phase time reflect China's development speed and political extreme height.
According to the arrangement of the State Council executive meeting at the beginning of this year, the fifth phase of the vehicle diesel standard (sulfur content not exceeding 10ppm) will be released before the end of June this year, and the fifth phase of vehicle gasoline standard (sulphur content not more than 10ppm) will be released before the end of this year. The transition period is until the end of 2017. The fifth phase of motor vehicle emission standards has gone through all the procedures and will soon be released. “Ministry of Environmental Protection officials stated that “the implementation of the standard will not be implemented immediately, because the implementation of the new standard requires a preparation period. Usually, this preparation period is three to five years. The official explained that the implementation of automobile emission standards must be preceded by oil.
Therefore, what is most important for the implementation of the new standard is that oil supply companies must fully prepare to ensure that they can provide users with the five oil products that are compatible with emission standards. At the same time, automobile manufacturers must also develop and produce new emissions standards. The car, the user must wait for the government's subsidy policy to decide whether to eliminate old cars.
This year, with the approval of the State Council, since February 1, 2013, Beijing has taken the lead in the nation to implement the fifth phase of Beijing's motor vehicle sprinkler discharge standards. Among the ten measures put forward by the State Council, the seventh measure is to use laws and standards to force industrial transformation and upgrading, including an important content, and formulate and revise the emission standards for key industries.
â— What is the automotive emission standard?
At present, the world's automobile emission standards stand side by side, divided into three major European, American and Japanese standards. European standards test requirements are relatively broad, and are the exhaust gas emission systems most of the developing countries use. Japan and the United States are the most rigorous. Most of China's automakers introduce production technology from Europe. Therefore, they generally adopt the European standard system. Their sprinkler exhaust emission standards also extend to the European standard system.
Vehicle emission standards refer to harmful gases such as CO (carbon monoxide), HC+ NOx (hydrocarbons and nitrogen oxides), and PM (particles, soot) discharged from the exhaust gas. Vehicle emissions refer to harmful gases such as CO (carbon monoxide), HC + NOx (hydrocarbons and nitrogen oxides), and PM (particles, soot) that are emitted from the exhaust gas. They are all harmful gases produced by the engine during the combustion process.
The causes of these harmful gases vary. CO is an intermediate product of incomplete oxidation of fuel. When the oxygen is insufficient, CO is produced. The high concentration of the mixture and the non-uniform mixture result in an increase in CO in the exhaust. HC is an unburned material in fuel. Some fuel will be discharged in the future due to non-uniform mixture and cold combustion chamber walls. NOx is a substance produced by the fuel (gasoline) during the combustion process. PM is also a substance produced by oxygen deficiency when the fuel is burned, among which the most obvious is the diesel engine. Because the diesel engine uses compression ignition, diesel cracking at high temperatures and pressures is more likely to produce a large amount of visible soot.
In order to curb the production of these harmful gases and urge auto manufacturers to improve their products in order to reduce the sources of these harmful gases, Europe and the United States have established relevant automobile emission standards. Among them, the European standard is the automobile emission standard that our country learns from. At present, new domestic vehicles will specify the European standards for engine exhaust emissions.
European standards are jointly implemented by the European Economic Committee (ECE) emission regulations and the European Community (EEC) emission directives. The European Community (EEC) is now the European Union (EU). Emissions regulations are voluntarily recognized by participating countries of ECE, and emission directives are enforced by EEC or EU participating countries.
The European Regulations (Directives) Standard for Sprinkler Truck Automobile Emissions was implemented several stages before 1992. Europe has been implementing Euro I (European Type I certification emission limits) since 1992 and Euro II Type II (European Type II Certification) since 1996. And Production Consistency Limits of Emissions. Since 2000, Euro III (European Type III Certification and Production Consistency Emission Limits) has been implemented. Since 2005, Euro IV (European Type IV Certification and Production Consistency Emission Limits) has been implemented. .
â— Euro IV emission technology
European emission standards:
Euro 0: purely mechanical fuel supply system (fuel pump or diesel pump) and naturally aspirated technology. Euro I stage: Based on the Euro 0 engine's mechanical fuel supply system (fuel pump), it is mainly supplemented with exhaust gas turbocharging technology.
Euro II stage: Appropriate improvement on Euro I engine platform, mainly supplemented by exhaust gas turbocharging (water and air) intercooling technology or exhaust gas turbocharged intercooling technology, and the oil supply system has no essential changes.
Euro III: Major upgrades to the Euro II engine platform, mainly due to the essential changes in the oil supply system, and the transformation of the oil supply system from mechanical control to electronic control. The main technical route includes electronically controlled pump nozzles and electronically controlled high voltages. Common rail, electronically controlled monomer pump and electronically controlled H pump + EGR. The EGR (Exhaust Gas Recirculation) technology is mainly for the exhaust gas purification device installed for harmful gases (NOx). It combines a part of the exhaust gas into the intake pipe and mixes with fresh air and then enters the cylinder to burn to increase the heat capacity of the mixture and reduce the combustion time. The highest temperature suppresses the formation of NOx.
Euro IV: At this stage, PM and NOx emissions are further limited. The technical route is based on the Euro III engine. There is no essential change in the oil supply system. The main method is to adopt a series of internal purification technologies such as increasing oil supply. The control sensitivity and pressure of the system, the combustion chamber and the intake air are further optimized, and the external purification (post-processing) technology is comprehensively used. External purification (post-processing) technology currently has two main technical routes: one is SCR (Selective Catalytic Reduction) technology, which purifies PM through the machine, external catalytic reduction; the other is EGR (exhaust gas recirculation) + DPF (particulate trap) + DOC (oxidation catalytic converter) technology reduces NOx through on-board purging, and filters PM outside the chiller through particulate traps.
Euro V stage: At this stage, the requirements for PM are the same as those for Euro IV, and only the NOx emission is further limited. The technical route is based on the Euro IV engine, and the corresponding adjustments are made according to the different technical routes taken in the Euro IV stage. Engines using SCR technology are relatively easy, requiring only partial adjustments on parts and electronic control parameters, while engines using EGR technology need to be redesigned on oil pumps and other pipelines.
Europe and the United States mainly used two off-machine post-processing technology routes:
1. SCR (Selective Catalytic Reduction) technology route, through optimization of fuel injection and combustion process, to control the generation of particulates in the machine as much as possible. In the off-machine post-treatment process, selective catalytic reduction of NOx is performed using urea solution. The Cummins, Mark, Detroit diesel engines, DaimlerChrysler, Volvo, Duff, and Iveco are the main technologies that use this technology.
2. EGR+DPF/DOC (Exhaust Gas Recirculation + Particulate Trap/Oxidation Catalytic Converter) technology route, based on exhaust gas recirculation, suppresses the generation of NOx in the machine and uses particulates in off-machine post-processing The trap captures the particles. At present, Cummins, Caterpillar, IWC, Scania, Mann, etc., are the main adopters of this technology route.
With the SCR scheme, no further strengthening of the engine is required. The sulfur content in the fuel has less impact on the system and can avoid the high sulfur content of the fuel. Using the SCR scheme can save fuel consumption by about 5% by adjusting fuel injection characteristics. The entire vehicle requires an additional urea storage and conversion device, which increases costs. The use of EGR+DPF/DOC scheme requires strengthening of the original engine to improve the injection pressure and booster cooling capacity. In Europe, SCR technology dominates, while in North America, EGR+DPF is the mainstream. At present, China's mainstream truck manufacturers' national IV models and the adopted technical routes have relatively recognized the SCR technology route.
â— European standard engine technology difference
To meet the EU VI and EU V standards, sprinkler engine manufacturers will have to adopt technical measures such as engine improvement, the use of extremely low sulphur fuel and emission control systems. Euro VI and Euro V standards require that the sulphur content of diesel fuel does not exceed 50X10-6, while the U.S. 2007 and 2010 Act rules require the sulphur content of diesel fuel to be reduced to 15 x 10-6. The European V and European VVI standards are mainly aimed at particulate emissions, which poses greater challenges for diesel engines to reduce 002it.
As the most widely used power source engine, the diesel engine has an overall technical structure similar to that of the diesel fuel system and the electronic control system, ie, an in-line mechanical pump and an electronically controlled common rail system. At present, on behalf of the international advanced level, Germany's BOSH company has its common rail fuel system emission standards within Euro III (National 3). It uses a crankshaft, connecting rod, crosshead structure, pump pressure 130Mpa.
The Euro IV standard requires that the pressure of the oil pump be increased to 160 MPa. This relatively simple structure has not been adapted. First, the plunger has a high precision and is difficult to process. Second, this design scheme uses a spring force point contact force structure. After the pressure rises, it is prone to the disadvantages of stuck and unsteady transmission. Therefore, the Euro V standard product has already covered the design principle of the traditional engine, especially the oil pump design principle, it is a revolutionary reinvention process that completely overturns the traditional theory.
The DOC technology device can oxidize soluble organic components (SOF) in total particulates (TPM) to CO2 and water. It also oxidizes the CO and HC in the exhaust gas into CO2 and water. Unlike controlling TPM, HC, and CO emissions, NOx needs to be reduced to nitrogen (N2) and water.
Its technical principle is: (1) SO3 in engine discharge will generate sulfuric acid when it meets water, which is part of TPM; (2) Sulfur is easily oxidized from SO2 to SO3 by most of the platinum catalysts used in emission control systems; (3) Sulfur It will poison the lean NOx trap (LNT) and catalysts such as palladium. There is a need for a technology that can oxidize CO and HC without oxidizing SO2. A sulfate inhibitor can alter the selectivity of platinum. Reduce SO2 activity.
Some methods are used to overcome the low reactivity of TPM: (1) oxidize the SOF component in TPM; (2) trap particles in a filter and oxidize it at high temperatures; (3) oxidize to NO2 through NO, This produces a more reactive oxide form.
According to relevant data, the use of filters to trap TPM and periodically regenerate the filter at high temperatures has been put into commercial use in all heavy-duty diesel vehicles in the United States in 2007 and in most diesel passenger cars in Europe. In the event that there is a need to reduce particulate emissions and the use of platinum, almost all use NO2 to oxidize soot. In some situations where it is not necessary to completely filter the TPM, it is sufficient to use a split filter or a standard gas flow through the carrier. A set of DOC devices can remove 20% to 60% of the particles in the exhaust gas. The first technology to remove NOx is lean NOx catalysis (LNC). This technology has been applied to light-duty diesel vehicles in applications requiring 5% to 10% reduction in NOx emissions. Adding additional HC in the exhaust gas can increase the NOx reduction to 10%-20%.
However, its disadvantage is that most LNC catalysts generate a large amount of N2O between 150-200°C. The diesel LNT absorbs NOx in the LNT under lean conditions until the amount of NOx reaches the LNT capacity. Desorption begins when NOx peaks and reacts with CO and HC to produce N2 and water. This technology was originally applied to passenger cars and medium-duty trucks in the United States. However, the sulfur in the fuel will have a great influence on the performance and durability of the LNT.
The reducing agent used by SCR technology is not CO and HC but ammonia. The SCR reductant used in automobiles is usually a 32.5% (mass percentage) liquid urea solution. There are several commercial SCR catalytic devices available today, including vanadium oxides, low temperature zeolites, and high temperature zeolites. The vanadium-based SCR device is suitable for operation in the temperature range of 200-550°C, but it quickly loses its activity when it is exposed to an environment above 600°C. The temperature of the low-temperature zeolite device is 150-450°C and is being prepared for light-duty diesel passenger cars. The temperature at which the high-temperature zeolite functions is 250-700°C (the installation of the DOC device in front of the SCR device may lower the temperature limit at which it works) to 200°C.
The high-temperature zeolite device will be mainly used for NOx reduction of 2010 and Euro IV engines in the United States. The filter device requires active regeneration above 600°C, and engine manufacturers face design choices: engine NOx emission control and TPM emission control system In combination, or engine TPM emission control combined with NOx emission control system. European OEMs have chosen the former, but most engine manufacturers have chosen SCR because it allows the engine to be optimized for low particulates, high NOx, and maximum fuel economy.
In addition, the existing SCR emission control system in Europe has the ability to meet Euro V emission standards with minimal changes (providing higher urea injection rates, etc.). European heavy-duty diesel vehicles have chosen the vanadium-based SCR system because it has the best cost-effectiveness ratio. It is also possible to achieve a NOx conversion rate of 60%-70% that is required by the Euro IV standard without using a DOC device. This method can be used in areas where low sulphur fuels are not available.
â— National IV emission technology
At present, terms commonly used in China, such as Euro I and Euro V standards, refer to the Emissions Directive issued by the EEC. For example, the instruction "EEC88/77" applicable to sprinkler heavy-duty diesel vehicles (mass greater than 3.5 tons) is divided into two phases. Phase A (ie, Euro I) is applicable to vehicles registered after October 1993; phase B (ie, Euro II applies to vehicles registered after October 1995. The contents of the European Regulations (Instructions) for Automobile Emissions include the type certification test for newly-developed vehicles and the production consistency inspection test for existing production vehicles, and the production consistency check for in-use vehicles has been added since Europe III. According to relevant data, the measurement of European regulations (instructions) standards for automobile emissions is based on the amount of pollutants (g/km) traveled by the vehicle's engine unit distance, because it is reasonable to study the pollution level of automobiles to the environment. At the same time, European emission standards classify automobiles into two categories, total mass not exceeding 3,500 kg (lightweight vehicles) and total mass exceeding 3,500 kg (heavy vehicles). The light vehicle is tested on a chassis dynamometer whether it is a gasoline engine or a diesel engine. Due to the weight of the heavy machine, the heavy engine is tested on the engine pedestal using the mounted engine.
At present, there are two main types of domestic EGR: external EGR and built-in EGR. All major engine plants EGR engine and its technical route.
1. External EGR route. Typical features of electromechanical pumps and cooled exhaust gas recirculation technology are represented by heavy-duty trucks and Dachao Deutz. Electronically controlled EGR valves and electronic control units are installed outside the engine case, according to instantaneous operating conditions and exhaust gas control solenoid valves. Open to meet emission standards.
2, built-in EGR route. The technology accurately measures and controls the mechanical operation of the engine camshaft so that the cylinder exhaust valve maintains an opening of 3% to 6% during intake, so as to achieve the effect of mixing the overflow exhaust gas and the intake air in different proportions. Emissions to achieve country III. Representative companies include FAW Xichai, Yuchai and Dongfeng Cummins.
There are mainly four fuel system technical routes for domestic commercial vehicle diesel engines: Electronically Controlled Pump Nozzles (EUI), Common Rail, Electronic Unit Pumps (EUP), and Electronically Controlled Inline Pumps (EIL) + EGR.
Electronically Controlled Pump Nozzle Technology (EUI) was adopted by Volvo, Mann, Iveco, Dongfeng, Shaanxi Auto and other companies. In addition, all electronically controlled engines of Cummins of the United States are also electronically controlled pump nozzle technology. Currently, the global ownership of engines using this technology With more than 400,000 units and a mileage of 300 billion kilometers, it is a proven and mature product.
Common rails for the sprinkler system include Volvo, Mercedes-Benz and Mann. Domestic companies include Shaanxi Auto, Liberation, Auman, and Hongyan. Domestic engine manufacturers include Weichai, Yuchai and Xichai. The high pressure common rail technology has become the most widely used technology that can currently achieve the National III emission standard.
EPUs are used in Mercedes-Benz, Perkins, Iveco, Deutz, and Deutz FAW Dachai and Yuchai.
Sprinkler Electric Inline Pump (EIL) +EGR Technology China National Heavy Duty Truck, FAW Xichai, Yuchai, Shangchai, Weichai, East, West Cummins, etc. also provide electronically controlled inline pump + EGR engine.
â— National five emission technical indicators
The national five emission standards are based on the Euro V emission standards, in which the PM value is limited, the national five emission standards are 4.5 milligrams per kilometer, and the Euro five emission standards are 5 milligrams per kilometer, but the Beijing Five and the State Five emission standards are more than the Euro five emission standards. Be stricter. According to the Beijing Five-Emissions Standards Consultation Draft, among the three pollutants, the CO emission standard is still 1g/km, the HC compound emission standard is still 0.1g/Km, and the NOx compound standard is 0.08g. /km is further tightened to 0.06g/Km. Although the limit value standard for the HC compound in the Beijing Five emission standard is still 0.1 g/Km, the non-methyl alkyl hydrocarbon (NMHC) is listed separately in the HC compound, and the limit value is set to 0.068 g/km. NMHC refers to all hydrocarbons except methane. NMHC in the atmosphere exceeds a certain concentration, and besides being harmful to human health, it can also produce photochemical smog through sunlight under certain conditions, causing harm to the environment and humans.
According to research by Chery Automotive Engine Co., Ltd. to Mr. Moh, he pointed out that the Beijing Five-emissions standard specifies the PM value, but it is limited to direct-injection engines. The PM value of a gasoline engine is generally not high, and the PM value of a direct injection gasoline engine and a diesel engine is relatively high.
The Beijing Five emission standard stipulates that the PM value of the direct-injection gasoline engine in the cylinder is 4.5 milligrams per kilometer, and that in the Euro 5 emission standard is 5 milligrams per kilometer. The number of qualifying mileage for emissions from the Beijing Five Emissions Standard has been increased to 160,000 kilometers, which is a 60% improvement over the 100,000 kilometers of the National IV emission standard.
Compared with the reduction of pollutants, the upgrading of this milestone in the Euro 5 standard attracted more attention at the time. Because the American Standard has long been used as a term of 100,000 miles, a longer effective emission milestone has also been implemented in the Euro V. The meaning of this kilometer limit is that qualified automotive products must comply with the provisions of the Beijing Five-Three Major Pollutant Emission Limit within 160,000 kilometers.
In the Beijing Five Emission Standard, in principle, more detailed stipulations have been made on the self-inspection of vehicle manufacturers: sampling from 15,000 to 300,000 kilometers in the first year, sampling from 30,000 to 30,000 kilometers in the second year, and sampling from 50,000 to 80,000 in the third year Kilometers, sampling 8-10 thousand kilometers in the fourth year, sampling 10-16 thousand kilometers of in-service vehicles in the fifth year. The limited changes in emission milestones and the increased number of in-use vehicles for sampling projects are the most stringent aspects of the National V.5 and Beijing V.4 emission standards upgrades. If the oil cannot meet the requirements, the vehicle's emission stability will be difficult to meet, because sulfur, manganese, etc. in gasoline will poison the three-way catalyst (chemical reaction with the precious metal and reduce the catalytic ability of the precious metal). Directly reduce the efficiency of the three-way catalytic converter.
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