The turbine impeller, compressor impeller and sealing sleeve are installed on the turbocharger shaft to form the turbocharger rotor. The exhaust gas pressure from the exhaust manifold makes the turbine rotate at high speed, and the pump wheel on the same shaft rotates with it, and the intake pressure is input into the cylinder. Due to the direct impact of exhaust gas, the rotor becomes particularly hot and rotates at high speed, so it must be heat-resistant and wear-resistant, that is, the turbine adopts super heat-resistant alloy or ceramics.
The rotating speed of the rotor is above 100000r/min, and the highest can reach 200000r/min, so the balance of the rotor is very important. The supercharger shaft is subjected to alternating bending and torsion stress in work, so it is generally made of alloy steel with good toughness and high strength.
The structure of turbocharger bearing is one of the keys to the reliability of vehicle turbocharger. Modern vehicle turbochargers all adopt floating bearings. The floating bearing is actually a ring on the shaft. There are gaps between the ring and the shaft and between the ring and the bearing seat, forming a double-layer oil film, that is, the ring floats between the shaft and the bearing seat. The floating bearing is made of tin-lead bronze alloy, and the surface of the bearing is coated with a layer of lead-tin alloy or indium with a thickness of 0.005 ~ 0.008 mm. When the supercharger works, the floating bearing rotates between the shaft and the bearing seat.
The axial thrust generated by the supercharger during operation is borne by the thrust bearing arranged at one side of the compressor. In order to reduce friction, four oil distribution grooves are respectively machined on the thrust surfaces at both ends of the integral thrust bearing; Oil inlet holes are also machined on the bearing to ensure lubrication and cooling of the thrust surface.