The main function of turbocharging is to increase the air intake of the engine, thus improving the power and torque of the engine and making the car more dynamic. After the engine is equipped with turbocharger, its maximum power can be increased by 40% or even higher than that without turbocharger. This means that the same engine can output more power after being supercharged. Take our most common 1.8T turbocharged engine as an example. After supercharging, the power can reach the level of 2.4L engine, but the fuel consumption is not much higher than that of 1.8L engine. Another level is to improve fuel economy and reduce exhaust emissions.
negative impact
However, after supercharging, the pressure and temperature of the engine increase greatly, so the life of the engine will be shorter than that of the engine with the same displacement and without supercharging, and the mechanical properties and lubrication performance will be affected, which also limits the application of turbocharging technology in the engine to some extent.
You may think that the turbocharger is complicated, but it is not. Turbocharging device is mainly composed of turbine chamber and supercharger. First, the air inlet of the turbine chamber is connected with the exhaust manifold of the engine, and the air outlet is connected with the exhaust pipe. Then the air inlet of the supercharger is connected with the air cleaner pipeline, and the air outlet is connected with the air inlet manifold. Finally, the turbine and the impeller are respectively installed in the turbine chamber and the supercharger, and are coaxially and rigidly connected. Such an integrated turbocharging device is completed, and your engine is "overclocked" like a computer CPU.
The turbocharging device we usually talk about is actually an air compressor, which increases the air intake of the engine by compressing air. Generally speaking, turbocharging is to use the inertia impulse of the exhaust gas discharged by the engine to drive the turbine in the turbine room, and the turbine drives the coaxial impeller to pressurize the air sent by the air cleaner pipeline into the cylinder. When the engine speed increases, the exhaust gas discharge speed increases synchronously with the turbine speed, and the impeller compresses more air into the cylinder. With the increase of air pressure and density, more fuel can be burned. The output power of the engine can be increased by increasing the fuel quantity and adjusting the engine speed accordingly.
Turbocharging can be basically divided into the following systems according to the working mode:
(1) Exhaust gas turbocharging system. The engine has no mechanical relationship with the supercharger, and its compressor is mainly driven by the exhaust gas of the internal combustion engine to maintain power. In general, the pressurization pressure can reach 180~ 200Kpa or even 300Kpa, and the high-temperature compressed air is cooled by installing an air cooling device. So as to achieve the purpose of supercharging by using the exhaust gas discharged by the engine. This supercharger is used in all kinds of cars. Main advantages: efficiency improvement is greater than mechanical pressurization.
Main disadvantages: Because the throttle is slightly faster than the power output speed of the engine, it is usually necessary to wait a little after increasing the throttle, and after a while, the engine will burst into violent power, which is also commonly known as "turbo lag" (strictly speaking, it cannot be considered as a disadvantage); At the same time, because the engine exhaust gas needs to push the turbine after it is discharged from the cylinder, the exhaust gas encounters obstacles in the movement of the exhaust pipe, which increases the exhaust back pressure and affects the smoothness of the cylinder exhaust.
(2) Mechanical supercharging system. The mechanical supercharging system connected by the crankshaft and belt of the engine is installed on the engine. When the engine is working, the rotor rotation of the supercharger is supported by the power of the output shaft, and the air is pressurized until it is blown into the air inlet. Main advantages: the engine speed is synchronous with the supercharger rotor speed, without leading or lagging, and the engine power output is smooth and stable.
Main disadvantages: Mechanical supercharging is inevitable because of high friction, high power consumption and low supercharging efficiency.
(3) Compound supercharging system. When an exhaust gas turbocharger is used in an engine, a mechanically driven turbocharger is used. Of course, there are other supercharging methods, such as air waves supercharging and inertial supercharging.