Scavenging control method of homogeneous turbocharged direct injection gasoline engine

Abstract

The invention relates to a scavenging control method of a homogeneous turbocharged direct injection gasoline engine. The scavenging control method is characterized by including the following specific control steps that in a low-revolution-speed large-load area of the homogeneous turbocharged direct injection gasoline engine, the intake and exhaust variable valve timing (VVT) angle is controlled, and residual gas remaining in a cylinder is reduced; the purpose of controlling the scavenging amount is achieved by controlling the overlapping angle of the intake VVT opening angle and the exhaust VVT closing angle; weak scavenging or strong scavenging can be selected through a precise gas amount and fuel amount control system in a scavenging area according to the central temperature of a catalytic converter, and the fuel injection quantity is calculated according to the quantity, calculated through a model, of fresh air in the cylinder and the target value of the air-fuel ratio in the cylinder; before the temperature of the catalytic converter reaches an ignition temperature, a weak scavenging mode is adopted by the system, the temperature of the catalytic converter can be quickly increased, and the ignition time of the catalytic converter is shortened; and after the temperature of the catalytic converter exceeds the ignition temperature, a strong scavenging mode is adopted by the system, an exhaust-temperature low supercharger can work for a long time, and compared with the weak scavenging mode, the higher torque and the higher power output can be provided. By means of the method, the temperature of the catalytic converter can be quickly increased through after-burning; during strong scavenging, the fuel injection quantity can be calculated through the model, the air-fuel ratio in the cylinder is made to be 1, the exhaust temperature is lower than that of the weak scavenging mode, and long-time work can be achieved; and the combustion torque and output power can be increased through both the weak scavenging mode and the strong scavenging mode.

Description

technical field [0001] The invention relates to a scavenging control method for a homogeneous supercharged direct-injection gasoline engine, belonging to the field of engine power output control. Background technique [0002] The increasingly stringent fuel consumption regulations require the engine to develop in the direction of small-displacement supercharging, followed by the problem of insufficient power output in the low-speed and heavy-load area. The power output of the engine is determined by the amount of fresh air that enters the cylinder and participates in combustion. The exhaust back pressure and exhaust flow in the low speed area of ​​the small-displacement supercharged direct-injection gasoline engine are low, and the exhaust flow is small, so that the supercharger cannot work, resulting in fresh air participating in the combustion. The amount is small, and the combustion torque is small. The scavenging control can increase the valve overlap angle, let fresh a...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem of insufficient power output in the low-speed region of the homogeneous supercharged direct injection gasoline engine, the object of the present invention is to provide a scavenging control method for a homogeneous supercharged direct injection gasoline engine, which supports two scavenging modes: weak scavenging And strong scavenging, this method is different from the existing control method, does not add an additional scavenging valve, based on the hardware of the variable intake timing (VVT) of the system, uses the scavenging control method, in the low speed of this type of engine The load area can increase the amount of fresh air participating in the combustion. The weak scavenging can calculate the fuel injection quantity through the model to make the air-fuel ratio at the catalytic converter be 1, and the temperature of the catalytic converter can be rapidly increased through afterburning; the strong scavenging can calculate the fuel injection quantity through the model to make the The air-fuel ratio in the cylinder is 1, the exhaust temperature is lower than that of the weak scavenging method, and it can work for a long time

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