After more than 100 years of development, ordinary internal combustion engine vehicles have gradually realized mechatronics and comprehensive application of modern high-tech technology, achieving high performance, and made significant progress in safety, environmental protection, energy conservation and low cost. However, with the rapid increase in global car ownership, the automotive industry has been plagued by depletion of energy, rising oil prices, global warming and corresponding carbon dioxide emissions. Therefore, it is increasingly urgent to improve the fuel economy of the engine under the premise of meeting the engine emission requirements. Since the fuel economy of gasoline engines is worse than that of diesel engines, reducing the energy consumption of gasoline engines has become a problem that must be solved in the automotive industry.
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Continued increase in vehicle production raises series of problems
The total global car ownership will increase from the current 800 million to 1.2 billion in 2020. In the middle of the 21st century, it will reach 3.8 billion, of which the car ownership in developing countries will increase by more than 15 times. At present, there are about 64 million new cars produced every year in the world. According to the average annual consumption of 10 to 15 barrels of oil and petroleum products per vehicle, the oil consumption of automobiles is 85 to 12.7 billion barrels per year, accounting for about the world's oil production. half. The exploitation of petroleum resources amounts to several billion tons per year. After long-term modernization and large-scale exploitation, oil resources are depleted. According to scientists' prediction, the oil resources on the earth can only last for 60 to 100 years according to the current mining level. In 2007, China imported 190 million tons of oil. It is estimated that by 2020, China's oil imports may exceed Japan's, making it the largest oil importer in the Asia-Pacific region. The Development Research Center of the State Council predicts that by 2010 and 2020, China's automobile consumption of oil will be 138 million tons and 256 million tons, accounting for 43% and 67% of the country's total oil consumption. Therefore, the energy crisis is an important issue that we must face.
The growth in car ownership has brought many problems, such as health threats, environmental pollution, climate change, energy shortages and traffic congestion. At present, air pollution has become a very serious problem in urban areas. The harmful emissions of automobiles have caused a public damage to the living environment of human beings. According to the data, 60% of the atmospheric pollutants in urban areas come from automobile exhaust. Global warming and climate change are attracting more attention, and the corresponding carbon dioxide emissions will become the main problem for automakers to solve. Around 2010, the balance of supply and demand of energy in developing countries will lead to fluctuations in world oil prices. While ensuring environmental protection, vehicles using alternative energy sources will become the focus of automobile manufacturers.
In 2008, the EU required car CO2 emissions to reach 140 g / km, for gasoline vehicles, the corresponding fuel consumption will reach 6 liters / 100 km; in 2012, CO2 emissions requirements reached 120 g / km. Therefore, reducing fuel consumption and reducing emissions will be an urgent problem for the automotive industry.
The development trend of gasoline engine technology
Since the fuel economy of gasoline engines is worse than that of diesel engines, reducing the energy consumption of gasoline engines has become a problem that must be solved in the automotive industry. The combustion theory of a homogeneous mixture with a theoretical air-fuel ratio is widely used in ignited ignition engines. Its greatest advantage is that it can use a three-way catalytic converter to reduce emissions of CO, HC and NOx. The downside is that high fuel economy cannot be achieved, and combustion technology is constantly evolving in order to improve the thermal efficiency of the engine and reduce exhaust emissions. The gasoline engine has undergone a change from the fully mechanically controlled carburetor oil supply to the use of electronically controlled injection, in-cylinder direct injection, electric auxiliary boost and electric valve, variable compression ratio, cylinder deactivation, etc. The solution will use combustion control technology that combines the advantages of gasoline and diesel.
The most representative of the three major gasoline engine technologies are:
a. Gasoline direct injection technology. It is a major research goal to develop an engine that has the advantages of a gasoline engine and has the advantages of high fuel economy of the diesel engine. Direct injection in gasoline cylinders is an important means to improve the fuel economy of gasoline engines. In recent years, the research and application of a new mixed gas formation mode represented by Gasoliine Direct Injection (GDI) has greatly improved the gasoline engine. Fuel economy. The non-homogeneous direct injection technology represented by Japan faces problems such as combustion stability and post-treatment, and homogenized direct injection technology represented by Europe is emerging.
b. Electric and camless engines. The Variable Valve Timing (VVT) is designed for use in conventional automotive engines where certain important engine performance is not adequately met throughout the operating range due to fixed valve timing. . VVT technology provides the best valve timing in the range of engine operating conditions, which better solves the contradiction between high speed and low speed, power and economy under heavy load and small load, and at a certain extent to a certain extent. Improved emissions performance. With the requirements of environmental protection and sustainable human development, low energy consumption and low pollution have become the development goals of automotive engines. Due to its own advantages, VVT technology has been paid more and more attention, especially the rapid development of electronic technology, which promotes the development of VVT technology from the research stage to the practical stage. Electric valves have the same important meaning as electronically controlled injections. They will bring a series of technological changes to engine air system control and cycle process management, such as canceling the throttle, variable compression ratio, and partial cylinder deactivation.
c. Mixing of combustion methods. The combustion process of a conventional spark-ignition engine is much higher in the flame propagation than the unburned mixture. Therefore, this combustion process is uniform even when the gas mixture is mixed, but the temperature distribution is still uneven, and local high temperature causes NOx formation in the region where the flame passes. The combustion process of a diesel engine is a diffusion type. The combustion rate in the combustion process is determined by the mixing rate. The ignition occurs at many points. This type of combustion process is uneven in mixing and combustion, and NOx is generated in a relatively high temperature region where combustion occurs. Solid particles are produced in a high temperature zone where the fuel is concentrated. In the Homogeneous Charge Compression Ignition (HCCI) process, theoretically a homogeneous mixture and residual gas, ignited by compression throughout the mixed gas, the combustion is spontaneous, uniform and without flame propagation, This prevents the formation of NOx and particulates. This kind of gasoline engine homogenization is combined with diesel engine compression ignition. Based on fuel technology and control technology, the homogeneous compression ignition HCCI internal combustion engine technology, which combines the advantages of both gasoline engine and diesel engine, is emerging.
Infineon gasoline engine combustion control solution
The difference in the mixture formation strategy is the main difference between the port-fuel-injection (PFI) engine and the GDI engine. In the PFI engine product, 20% of the nozzle is mounted on the cylinder head. On the back of the intake valve, 80% is installed on the intake manifold near the cylinder head. When the engine starts, a transient liquid film is formed near the intake valve. These fuels will gradually evaporate into the cylinders during each intake process. Therefore, the oil film at the air inlet is like a capacitor and has an integral function. The instantaneous fuel supply of the engine cannot be accurately controlled by the injector. Due to the partial evaporation phenomenon, the oil quantity control delay and the metering deviation, due to the difficulty of fuel evaporation during the cold start, the actual oil supply is much larger than the fuel supply of the required air-fuel ratio, which will result in 4 to 10 cycles of the engine during cold start. Unstable combustion significantly increases the emissions of unburned HC from the engine. As shown in the figure, GDI engine fuel is directly injected into the cylinder, which can avoid the wet wall phenomenon of the valve port and achieve accurate fuel supply in all stages of combustion, thus enabling more lean combustion and reducing cylinder-to-cylinder circulation and circulation. The change between the first cycle of the cold start does not require rich control to reduce the HC emissions in transient conditions. However, GDI engines have stricter requirements for fuel evaporation and mixture formation, and need to increase the atomization rate of fuel through higher injection pressure, and require more complicated control strategies, which puts higher demands on the electronic control system of GDI engines. Requirements.
GDI engine control system schematic
Infineon is the world's leading provider of chip-level solutions for power system electronic control units. It is widely used in engine EFI controllers from Bosch, Continental, Delphi and other companies. It can be supplied in the electronic control unit of the power system. Master control microcontroller, power drive, sensor, communication, ASIC and other complete products. Infineon offers complete GDI engine control system solutions
The main control chip uses TriCore, a 32-bit superscalar architecture with integrated microcontroller and DSP processor architecture. It has fast interrupt response and is optimized for cost-sensitive real-time embedded systems. The next-generation vehicle controller with very good price/performance ratio, its main features are as follows:
1. 32-bit high-performance CPU: integrated multiply-adder, floating-point arithmetic, high-performance on-chip peripheral bus, bit control capability and flexible power management;
2. Rich on-chip memory cells: 1.5~2M PFLASH, 16K SPRAM, 56K LDRAM, 32K DFLASH, and TriCore's unique PCP storage area;
3. Rich interrupt resources: 256-level interrupt priority, 103 interrupt node requests, CPU and PCP have independent interrupt servers;
4. With PCP (peripheral control processor) function: can realize data transfer, interrupt service and basic operations;
5. DMA: With 8 independent DMA channels, 32bit addressing, reducing the burden on the CPU;
6. Universal Clock Array GPTA: Based on the parallel high-speed PWM generated by GPTA, the power-driven device can be directly managed by the MSC without software participation.
Infineon also offers highly integrated intelligent power driver chips in the GDI engine solution:
1. In the electronic throttle and EGR (exhaust gas recirculation) valve control, the intelligent H-Bridege driver chip TLE8209 is provided. The chip integrates functions such as overcurrent protection, fault diagnosis and SPI interface.
2. In the direct injection gasoline engine nozzle drive circuit, a chip TLE6270 capable of peak/hold feedback control is provided;
3. High-integration intelligent power driver FLEX 10/12 chip with Infineon's unique microsecond technology is provided in the driver chip of VVT and solenoid valve, which can realize multi-port drive and diagnosis functions;
4. Power management, providing intelligent power chip TLE7368 with integrated hardware watchdog, 3 DC/DC modules and multiple sensor power supplies;
5. CAN interface chip TLE6251DS and LIN interface chip TLE7259G are provided for communication.
Summary of this article
The continued development of automobile production faces many problems, and reducing fuel consumption and carbon dioxide emissions will become major problems for automakers. The gasoline engine will adopt the technology of direct injection in the cylinder, electric auxiliary boost, electric valve, variable compression ratio, cylinder deactivation, etc., and the final scheme will adopt the combustion control technology that combines the advantages of gasoline engine and diesel engine. This puts higher requirements on the performance of the gasoline engine electronic control system. Infineon offers a complete GDI engine control system solution that not only provides the high-performance 32-bit processing chip TriCore, but also provides highly integrated intelligent power driver chips and information sheets to meet the future needs of automotive manufacturing.
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