Composition and working principle of exhaust gas turbocharger

Working principle of exhaust gas turbocharger: exhaust gas turbocharger uses exhaust gas from engine to boost pressure.

The supercharger has no mechanical connection with the engine, and the exhaust gas from the engine drives the turbine. Its advantage is that the supercharging efficiency is higher than that of mechanical supercharging system, but compared with mechanical supercharging system, the supercharging effect lags behind the throttle opening.

Structure composition of exhaust gas turbocharger

Exhaust gas turbocharger is mainly composed of turbine and compressor. The exhaust gas discharged by the engine is introduced into the turbine, and the turbine is driven to rotate by the energy of the exhaust gas, so as to drive the compressor coaxial with the turbine to realize supercharging. The inlet of the turbine is connected with the exhaust manifold of the engine, and the outlet is connected with the exhaust pipe; The air inlet of the compressor is connected to the air cleaner, and the air outlet is connected to the intake manifold.

turbine

Turbine is a device that converts the energy of engine exhaust into mechanical work. It consists of a fixed nozzle ring, a rotating impeller and a turbine shell. The combination of nozzle ring and impeller is called turbine stage. In some small turbochargers, in order to reduce the volume, reduce the weight and simplify the structure, the nozzle ring is often cancelled, and the turbine shell has the function of nozzle ring, which is called bladeless turbine shell.

The impeller of the turbine and the working wheel of the compressor form a rotor with a rotating shaft. The rotor is supported by radial bearings and axial thrust bearings. Because the rotor speed is high, it is necessary to strictly check its dynamic balance and reasonably select the bearing type to ensure the reliable operation of the turbocharger.

compressor

Also known as centrifugal compressor, it consists of inlet, working wheel, diffuser and outlet volute. In a small turbocharger, the inlet volute and the outlet volute are arranged on the same casing, which is called the compressor casing. Diffuser is divided into vaneless diffuser and vaneless diffuser.

Working principle of exhaust gas turbocharger

The exhaust gas turbocharger is actually an air compressor, which compresses air to increase the intake air. It uses the inertia impulse of the exhaust gas discharged by the engine to push the turbine in the turbine chamber, and the turbine drives the coaxial impeller to pressurize the air sent by the air cleaner pipeline into the cylinder. The pressure and density of air entering the cylinder increase, so more fuel can be burned. The output power of the engine can be increased by increasing the fuel quantity and adjusting the speed of the engine accordingly.

This kind of engine uses the energy of exhaust gas from the engine to impact the turbine installed in the exhaust system, making it rotate at high speed and driving the compressor to rotate together. The compressor compresses the intake air, forcibly pressurizes the intake air, and then sends it into the cylinder. Because the engine power is proportional to the intake air amount, the engine power can be increased. Modern supercharged engines generally refer to turbocharged engines.

When the turbine works, the internal pressure will be high. Although the turbine body has a hole to release high-pressure gas, there are still some shortcomings in the face of continuous pressurization. High-pressure gas can be released quickly through the pressure relief valve for the next pressurization. This can not only protect the turbine, but also eliminate some turbine hysteresis.