With the increasing awareness of environmental protection and the intensification of the energy crisis, improving the fuel efficiency of gasoline engines has become an important issue in the automotive industry. The following are several key technical means that have played an important role in improving the efficiency of gasoline engines.
1. Intake and exhaust system optimization
Variable valve timing (VVT)
Variable valve timing technology optimizes the intake and exhaust processes by adjusting the time of valve opening and closing, thereby improving the efficiency of the engine. This technology can adjust the phase of the valve according to different working conditions, so that the engine can maintain a high efficiency under various operating conditions1.
Variable valve lift (VVL)
Variable valve lift technology further optimizes the intake and exhaust processes by adjusting the lift height of the valve. This technology can realize the switching of multiple cycle modes (such as Otto, Miller, Atkinson), thereby improving fuel utilization1.
2. Injection system improvement
High-pressure direct injection
The traditional manifold injection system has been replaced by a high-pressure direct injection system. High-pressure direct injection technology improves fuel atomization by injecting fuel directly into the cylinder at high pressure, promoting more complete combustion, thereby improving fuel efficiency1.
Multiple injection strategy
The multiple injection strategy achieves stratified combustion by injecting fuel multiple times during the combustion process, further improving fuel utilization1.
3. Combustion model innovation
High tumble ratio design
Modern engine design has changed from Pistonguide or Sparkguide to Airguide. The high tumble ratio design speeds up the combustion speed and increases Pmax by increasing the air flow in the cylinder, thereby improving fuel efficiency1.
4. Accessory system optimization
External EGR improvement
External exhaust gas recirculation (EGR) technology reduces combustion temperature and reduces nitrogen oxide emissions by reintroducing part of the exhaust gas into the combustion chamber, while improving fuel efficiency1.
Thermal management module upgrade
The upgrade of the thermal management module improves the engine's operating efficiency by optimizing the engine's thermal management, thereby improving fuel efficiency1.
5. Application of cutting-edge technology
Variable compression ratio technology
Nissan's variable compression ratio (VC-T) engine achieves optimal combustion under different operating conditions by adjusting the compression ratio, thereby improving fuel efficiency1.
Lean burn technology
Lean burn technology (such as SPCCI and HCCI engines) improves thermal efficiency by burning at a lower air-fuel ratio, thereby improving fuel efficiency1.
Exhaust gas energy recovery technology
Toyota's fourth-generation Prius hybrid engine uses exhaust gas energy recovery technology to improve overall fuel efficiency by recovering energy from exhaust gas1.
Electric turbine technology
Mercedes-Benz M256 engine uses electric turbine technology to improve engine response speed and fuel efficiency through electric turbocharging1.
6. Hybrid technology
Hybrid technology combines the advantages of internal combustion engines and electric motors, allowing the engine to operate only at the highest efficiency point, while other operating conditions are compensated by the motor and battery, thereby achieving higher overall efficiency1.
Conclusion
Improving the fuel efficiency of gasoline engines is a complex process that requires the comprehensive use of multiple technical means. The fuel efficiency of gasoline engines has been significantly improved by continuously optimizing the intake and exhaust systems, injection systems, combustion models and accessory systems, as well as applying cutting-edge technologies and hybrid technologies. However, as the improvement of thermal efficiency enters a bottleneck period, the industry will focus more on optimizing comprehensive efficiency in the future to achieve higher fuel economy and lower emissions.
