Research and Development Trends of Automotive Internal Combustion Engines
An increase in the compression ratio results in excessive pressure in the cylinder, which prevents the gasoline from being injected into the combustion chamber. In this case, high-pressure gasoline pumps and high-pressure screw injectors must be used. Usually, the pressure of the GDI engine's fuel supply system can be increased. Reaching 50.Okg/cm arts or more, it is much higher than the average engine of the normal intake port injection. The GDI engine is also not quite the same as the general engine in the intake section. To control the flow path of the intake air flow, the GDI engine adopts a vertical intake port and a concave bowl top piston. This kind of match is mainly to achieve layered lean combustion to save energy. The basic principle of the fuel is to use the special shape of the concave bowl top piston and the high pressure screw injector to control the rich oil and gas around the spark plug ignition point. Therefore, even if the air/fuel ratio of the mixture is as low as 40:1, GDI The engine can still operate smoothly and produce the same motivation. The GDI engine has greatly increased its oil supply pressure and compression ratio. Therefore, more robust and durable materials are used for all engine parts. Since GDI in-cylinder direct injection is performed only when the engine compression stroke is not completed, the ignition timing needs to be more accurate than the intake port injection. Therefore, the high-precision computer ECU is also very important when designing the engine. One ring. Layered lean combustion technology is to overcome the slow combustion of the port injection engine and incomplete combustion. After years of research and development, the existing direct injection system can only be done around the spark plug. Mixed oil and gas, the rest of the combustion chamber is completely air, so it can significantly increase the limit of lean combustion to air-fuel ratio below 40:1, so the fuel consumption is certainly a lot lower than the average engine.
How the GDI engine outputs high horsepower We know that naturally aspirated engine modifications must do two things: increase the compression ratio and the intake and exhaust, which is why the GDI engine can provide high output because the high compression ratio is inherently the GDI engine. Inherent, and the high inertia air flow caused by the vertical high-efficiency air intake can also promote more rapid air flow into the combustion chamber. When the piston reaches the bottom dead point, air forms a rolling air current in the cylinder. The piston is in compression stroke. The fuel is sprayed in a cylindrical shape toward the curved groove above the piston on the top of the bowl, causing high concentrations of oil and gas to accumulate around the spark plug. When the piston reaches top dead center. Spark plugs ignite mixed oil and gas. High-inertia air flow caused by the vertical high-efficiency intake port. When the GDI engine is operating, the ultra-lean combustion mode is usually used at a low speed and the high-power mode is used at a high speed. High-injection mode fuel injection time and ultra-lean combustion fuel injection time are completely different. When the GDI engine is in the ultra-lean combustion mode, the fuel injection action is in the compression stroke, and the fuel injector is directly sprayed with high-density live fuel. The top surface of the bowl is curved so that the layered combustion is achieved around the spark plug ignition point. In the high output mode, the fuel injection is performed during the intake stroke. The oil and gas are the same as the normal intake engine. It is in a homogeneous state to improve the combustion efficiency, and uses oil and gas to reduce the cylinder temperature.
Ultra-lean combustion mode is usually used at low speed and high output mode is used at high speed. As long as it is internal combustion, both the volumetric efficiency and the engine temperature can improve its performance. The GDI engine is just enough for both. Since the gasoline is not mixed with air before entering the cylinder, the air intake density can be increased. On the other hand, GDI engine can absorb a large amount of heat after gasoline is sprayed in the cylinder, so it can also effectively reduce the temperature in the cylinder, suppress the generation of knock and increase the density of the mixture; therefore With two advantages of engine operation, the GDI engine can easily achieve high output goals. Experiments show that the direct injection engine in the cylinder is about 10% higher than the inlet injection engine and the horsepower is also 10% higher.
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