When the turbocharger on the car is working, it has to withstand the impact of the high temperature and high pressure exhaust gas from the engine. The speed of the turbine is generally more than tens of thousands of revolutions, up to 200,000 revolutions per minute, and the temperature is as high as 900 to 1000 ℃ .
How does the turbocharger lubricate and cool under such high operating temperature and speed? Let's talk about this problem below.
The moving parts of the turbocharger are also the core components—turbine impeller, compressor impeller and rotor shaft. There are high-speed relative motions between the turbocharger housing and the turbocharger housing. This kind of speed cannot be withstood by ordinary bearings, so The bearing of the supercharger is a special floating bearing. It is actually a copper ring sleeved on the shaft and the shell, and there is a gap between the ring and the shaft and the ring and the bearing seat. When the engine is working, under the action of the oil pressure, a double oil film is formed in these parts, and the rotor actually floats on the oil film and rotates at high speed. Due to the extremely high speed and high temperature, this part also has extremely high requirements for lubrication and cooling.
If the supercharger cannot get good lubrication and cooling, it will cause abnormal wear of the bearing, greatly shorten the service life of the bearing, increase the gap between the rotor and the housing, and part of the oil will enter the intake pipe or exhaust pipe from this part , Leading to serious oil burning failure.
Poor heat dissipation can cause oil coking or coking
In addition, poor heat dissipation can cause oil coking or carbon deposits, which will further damage the seal and lubrication of the turbocharger, aggravate the wear, and eventually cause the turbocharger to leak oil or abnormal noise, and even get stuck. In order to cool and lubricate the turbocharger, a special oil pipe is separated from the main oil passage of the engine lubrication system, so that the oil enters from the oil inlet above the supercharger intermediate body and flows out from the oil port below the intermediate body for lubrication and Cool the supercharger rotor and bearings.
In order to ensure a good lubrication and cooling effect, the flow rate of this part of the oil is very fast and the flow rate is relatively large. In order to better cool the supercharger, some current models have added a set of water-cooling device, which is driven by an electronic water pump. It can still work for a few minutes after the engine is turned off to continue to dissipate the supercharger and prevent the supercharger from overheating. high.
Due to the special cooling and lubrication method of the turbocharger, there are also certain requirements on the use of the turbocharger. For example, do not run at high speed immediately after starting a cold car, do not run at idle for a long time, and do not run after a long period of heavy load operation. Turn off the engine immediately, do not blow the throttle before turning off, etc.
In addition, the turbocharger must use high-quality fully synthetic engine oil to prevent poor lubrication or oil coking at high temperatures. When replacing the turbocharger, a certain amount of engine oil must be injected into the turbocharger to prevent the moment the engine starts. The supercharger is not lubricated and burned.