What Is an Impulse Turbine?

Turbocharger is a technology that uses an exhaust gas generated by the operation of an internal combustion engine to drive an air-compressor.

Turbocharged

Turbocharger is a kind of utilization

The main role of turbocharging is to increase the engine air intake, thereby increasing the engine's power and torque, and making the car more powerful. After an engine is equipped with a turbocharger, its maximum power can be increased by 40% or more compared with the case without a turbocharger. This also means that the same engine can output more power after being supercharged. Take our most common 1.8T turbocharged engine. After supercharging, the power can reach the level of the 2.4L engine, but the fuel consumption is not much higher than the 1.8L engine. On another level, it is to improve Fuel economy and reduced exhaust emissions. ^[1]

However, after supercharging, the pressure and temperature of the engine during operation are greatly increased, so the engine life will be shorter than that of the same displacement without supercharging, and the mechanical performance and lubrication performance will be affected. To some extent, the application of turbocharging technology to engines is limited.

Turbine working principle diagram, red is high temperature exhaust gas, blue ^[2]

According to the use of exhaust energy in the turbine, it can be divided into the following two systems:

The turbocharger uses the exhaust gas from the engine to drive the turbine. How advanced is a set of mechanical devices? Because it often works at high speed and high temperature, the temperature of the turbocharger exhaust turbine end is above 600 degrees, and the speed of the turbocharger It is also very high, so in order to ensure the normal operation of the turbocharger, it is very important for its correct use and maintenance. The main methods we have to follow are: ^[3]

1. After the car engine is started, you cannot step on the accelerator pedal quickly. You should run at idle for three minutes. This is to increase the oil temperature and improve the flow performance, so that the turbocharger is fully lubricated, and then the engine speed can be increased. This is particularly important in the winter, as it takes at least 5 minutes to warm the car.

2. After the engine runs at high speed for a long time, it cannot be turned off immediately. The reason is that when the engine is working, part of the oil is supplied to the turbocharger rotor bearings for lubrication and cooling. After the running engine suddenly stops, the oil pressure drops rapidly to zero, the oil lubrication will be interrupted, and the heat inside the turbocharger will also be Can not be taken away by the engine oil. At this time, the high temperature of the turbo part of the supercharger will be transferred to the middle, and the heat in the bearing support shell cannot be taken away quickly, while the supercharger rotor is still rotating at high speed under the inertia. This will cause a seizure between the turbocharger shaft and the shaft sleeve, which will damage the bearings and shaft. In addition, after the engine suddenly shuts down, the temperature of the exhaust manifold is very high at this time, and its heat will be absorbed into the turbocharger housing, and the oil remaining inside the supercharger will be boiled into coke. When such carbon deposits accumulate more and more, the oil inlet will be blocked, resulting in a lack of oil in the shaft sleeve, which accelerates the wear between the turbine shaft and the shaft sleeve. Therefore, the engine should run at idle for about three minutes before the engine stops, so that the turbocharger rotor speed drops. It is also worth noting that the turbocharged engine is also not suitable for long-term idling, and should generally be kept within 10 minutes.

3. Pay attention when selecting oil. Due to the role of the turbocharger, the quality and volume of the air entering the combustion chamber has been greatly improved. The engine structure is more compact and reasonable, and the higher compression ratio makes the engine work more intensely. The machining accuracy is also higher, and the assembly technology requirements are stricter. All these determine the high-temperature, high-speed, high-power, high-torque, low-emission working characteristics of turbocharged engines. At the same time, it determines the working conditions of the engine's internal components to withstand higher temperatures and greater impact, compression and shear forces. Therefore, when selecting the engine oil for turbocharged cars, we must consider its special characteristics. The oil used must have good abrasion resistance, high temperature resistance, the establishment of a lubricating oil module, high oil film strength and good stability. Synthetic or semi-synthetic motor oils can just meet this requirement, so in addition to using the original factory oil, you can also choose high-quality lubricants such as synthetic and semi-synthetic motor oils.

4. The engine oil and filter must be kept clean to prevent impurities from entering, because the coordination gap between the shaft and the sleeve of the turbocharger is very small. If the oil lubricating capacity decreases, it will cause the turbocharger to be prematurely scrapped. .

5. The air filter needs to be cleaned on time to prevent dust and other impurities from entering the high-speed rotating pressure impeller, causing unstable speed or increased wear of the shaft sleeve and seals.

6. It is necessary to check the sealing ring of the turbocharger frequently. Because if the seal ring is not sealed, the exhaust gas will enter the engine lubrication system through the seal ring, the oil will be dirty, and the crankcase pressure will rise rapidly. In addition, when the engine is running at low speed, the oil will also be discharged from the exhaust pipe through the seal ring or Combustion into the combustion chamber, resulting in excessive consumption of engine oil resulting in "burning engine oil".

7. The turbocharger should always be checked for abnormal noises or unusual vibrations, and if there is any leakage from the lubricating oil pipes and joints.

8. The turbocharger rotor bearing has high precision, and the working environment during maintenance and installation is very strict. Therefore, when the turbocharger fails or is damaged, it should be repaired at a designated repair station instead of an ordinary repair shop .

9. To keep the air cleaner clean, compared to ordinary engines, turbocharged engines have higher requirements for cleaning. Because if the impurities enter the pressure impeller, it will cause unstable speed or increased wear of the sleeve and seal.

10. Keep engine oil clean. Turbocharged engines have high requirements for oil, and must be kept clean. In addition, if the oil deteriorates, it should be replaced in time. Otherwise, the lubricating capacity of the engine oil will be reduced, which will cause insufficient lubrication of the supercharger bearings and damage, increase maintenance costs, and even cause premature scrapping of the turbocharger.

11. It is not good for a turbocharged engine to leave the car and immediately stop it. It is best to run for a while after the engine is started, so that the lubricant can fully lubricate the bearings and protect the engine. In addition, after the engine runs at high speed for a long time, it should run at idle speed for 3-5 minutes before turning off. Otherwise, the oil retained in the turbocharger will overheat and damage the bearings and shafts.