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Home >> News >> High Pressure Common Rail Diesel Engine
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Monday 13th October 2014

A concept Interpretation

Common Rail (Common Rail) EFI technology is a closed loop system the high-pressure pump, a pressure sensor and an electronic control unit (ECU) in the composition, will result in the ejection pressure of the injection process and completely separate from each other, a fuel supply means. It is composed of a high pressure pump high-pressure fuel delivery to the public for the pipeline (Rail), to achieve precise control through hydraulic public for the pipeline within the high-pressure tubing pressure (Pressure) independent of the size of the engine speed, can greatly reduce diesel the extent of oil pressure with engine speed changes.

in the world

Currently there are three major companies in the world in the development and production of high-pressure common rail diesel systems, Denso, Bosch and Ford USA. The system will produce common rail fuel pressure and fuel injection separated, if the unit pump diesel injection technology likened revolutionary diesel technology, then it can be called a rebel rail, because it deviated from the conventional diesel system approximation in sequential fuel injection system. Common rail system opened up new ways to reduce diesel engine emissions and noise.

Because of its strong technical potential, today each manufacturer has their eyes set on the 3rd generation common rail system - piezoelectric (piezo) common rail system, instead of the piezoelectric actuator solenoid valve, thus obtaining a more accurate injection control. Without the return pipe, the structure is more simple. Pressure from 200 to 2000 Pa elastic adjustment. The minimum injection quantity can be controlled in 0.5mm3, and the smoke is reduced NOX emissions.

Increasingly serious energy crisis, became the focus of worldwide attention to the internal combustion engine industry, but also make diesel engines more and more users. Compared with gasoline diesel has many advantages: reducing by 20% to 25% of CO2 emissions, acceleration performance advantage when low speed, average fuel consumption of 25% to 30% lower, can provide more driving pleasure. Therefore, it was a bold development trend of global vehicle production in diesel engines were predicted, according to the proportion of the regional division of the world's automobile production in diesel engines. However, compared with the gasoline engine, diesel engine emission control is a difficulty. To meet the emissions standards, diesel fuel injection system --- advanced high pressure common rail technology industry has become the focus of attention. A few years ago , High-pressure common rail technology is foreign domination, and now this situation is broken.

Emission standards

December 30, 2005, Beijing first implementation of the country Ⅲ emission standards. July 31, 2006, Shanghai bus, taxi industry to implement a new car country Ⅲ emission standards. September 1, 2006, Guangzhou, China began to implement Ⅲ emission standards. July 1 this year, the country will fully implement the country Ⅲ emission standards. By 2010, the country will implement the country Ⅳ emission standards.

Emission standards improve, bound to promote the development of engine technology. For gasoline engines, due to the technology is relatively mature and post-processing, and therefore is not difficult to meet the current emission standards. For diesel engines, as most or mechanical fuel system, and diesel direct injection technology development process is shorter, and therefore in order to meet emission standards must be redesigned engine. Currently, most with the introduction of technology to meet emission standards (National Ⅲ) at this stage, but there are some companies conducting independent research and development, such as China FAW Wuxi Fuel Injection Equipment Research Institute, Chengdu Witt and so on. More stringent emission standards in the next, in addition to electronically controlled fuel system, engine machine also introduced a number of new technologies. World-renowned research institutions Ricardo automotive engine technology requirements recommended in various stages of emissions, which show common rail system because of its unique advantages, is one of the most inheritance and sustainable development of fuel injection system.

Universal application

After the development of diesel fuel injection system controlled from mechanical to electronic control systems, electronic injection system has experienced three changes that position type fuel injection system, fuel injection system time and time pressure fuel injection systems (common rail system). High pressure common rail system to achieve a pressure build-up and separation injection process, so that the control process more flexible, more accurately achieve precise control of a small amount of oil, to better achieve multiple injection.

Since 1991 the company issued Denso ECD-U2 common rail system papers since foreign fuel system manufacturers have invested huge amounts of money and manpower development common rail systems. Bosch published in 1995 a high-pressure common rail system for passenger cars, the use of radial piston rotor for pumps, injector solenoid valve with ball valve structure. Currently Bosch common rail system in the European diesel passenger cars and light trucks have been common applications, such as Germany's Daimler - Benz C-Series sedan, Italy AlfaRemeo156 cars, Volkswagen Audi 3.3L V8 turbocharged diesel engine type, U.S. General Motors joint venture with Japan's Isuzu diesel engine and the United States produced Duramax6600 company ISBe3.9L and 5.9L Cummins diesel Engine for and so on. Delphi and Siemens were launched in 1998 and 2000 cars MultecDCR1400 common rail system, the use of radial piston pump rotor for Delphi's solenoid valve injectors in the injector design, making the injector volume more compact; Siemens injectors using piezo actuators, the response time is shorter; while Denso Corporation research and development of ECD-U2 first-generation product in 1991, and matched the J08C Hino diesel engine in 1995, the 6HK1 Isuzu diesel engines, after years of improvement and perfection, the latest product has been used in cars ECD-U2P systems.

At present, the common rail fuel injection system applications are very common, Bosch has produced 25 million sets of common rail system, and in Wuxi, Jiangsu investment in building a technology center and factory, to achieve local production. Great Wall Motor and Bosch has developed a high-pressure common-rail diesel engine, in addition to Audi, Mercedes-Benz, Thailand and other brands also introduced the use of common rail system of the car. Some Chinese universities, research institutes and enterprises through cooperation or independent research and development, has made a distinctive research results, and several dozens of patents published. Therefore, in terms of our electronically controlled direct injection diesel engine has accumulated some experience, but overall there is a gap with foreign countries, mainly in the manufacturing process and quality control of mass production. In addition, the domestic rail system supporting system is not perfect, some parts still rely on imports, such as single chip, the rail pressure sensor.

Competitive situation

Relative to the gasoline engine, the electric control diesel engine in terms of domestic and foreign gap is relatively small. Thanks to two reasons: First, the use of existing diesel vehicles mostly have their own brands, the second is the use of diesel vehicles less demanding comfort, low price, Chinese enterprises to compete with foreign companies is not dominant.

With the improvement of emission standards, must be electronically controlled diesel injection system. At present, the main electronic control system of diesel common rail, unit pump, etc., and foreign advanced technology than, though not with equal strength, but the good momentum of development. Wuxi Institute of pump nozzle as common rail system has been developed for use in Wuxi bus while engaged in domestic electronically controlled diesel engine R & D enterprise in larger quantities, and thus the domestic market in the electronically controlled diesel engine will make a difference in the future. The price of foreign companies to provide relatively high supply prices depend on volume, electronically controlled diesel engine in the current batch of big premise is not difficult for them to get a more satisfactory price.

Meanwhile, in the after-sales service and spare parts supply, domestic independent brand system there are obvious advantages, electronically controlled fuel system competitiveness of domestic self-developed mainly reflected in the following aspects: First, the price is cheaper, smaller economic quantities. Secondly, for light truck products in bulk to match common rail technology is not the case, you can choose a high injection pressure PM-type electronic governor inline pump + + cooling EGR program, which is to our advantage. Also, for the heavy vehicles in the country Ⅲ stage has begun to implement common-rail, single pump technology route. It is also worth mentioning that the protection of high-pressure common rail diesel filter system security work to meet the requirements of the country three or more emission engine water separator, mostly foreign production, such as Bosch (BOSCH), Man Hu (Mann-Hummel) Parker (Parker), domestic brands rarely meet the standards, there are Suzhou Industrial Park, Da Feite (DIFITE) into the part of the host matches. Routine maintenance on high purchase and maintenance of diesel engine filters foreign compliance costs, if the driver does not raise awareness of the country, three filter maintenance, use cheap substandard country, three diesel filter, will cause total damaged rail system components, a large maintenance cost.

Of course, domestic diesel engine electronic control systems also face many challenges, such as manufacturing processes mature, smaller batch sizes; fuel quality is difficult to guarantee; after diesel processing technology level is not high. However, over time these will soon be solved step by step.

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