Variable Nozzle Turbocharger Bearing Clearance Design
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Solution Overview
Problem
Conventional variable nozzle units face challenges in assembly efficiency and operational stability due to nozzle axis inclination and wear, leading to non-smooth movement and potential malfunctions in turbo rotating machinery like turbochargers and gas turbines.
Innovation Solution
A variable nozzle unit design with two first bearing portions on each side of the shroud ring and a larger fitting clearance between the second bearing portion and the second nozzle shaft, allowing for stable support and reduced axis inclination, enabling improved assembly efficiency and operational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the variable nozzle is supported on both sides by first and second bearing portions, then the axis inclination of the variable nozzle is reduced, but the assembly work becomes complicated and requires special jigs
Solution Approach 1:
The patent removes the second bearing portion from the second base ring, extracting the problematic component that caused assembly complexity. The variable nozzle is now supported only by the first bearing portion on the first base ring, eliminating the need for special jigs and complex assembly procedures while maintaining adequate support stability.
2Ease of manufacture
If the variable nozzle is supported on one side by two first bearing portions, then the assembly work is simplified, but the axis inclination increases during operation
Solution Approach 1:
The patent divides the support function into two separate locations: the first bearing portion on the first base ring and the second bearing portion on the second base ring. This segmentation allows the nozzle to be supported at both ends, reducing axis inclination while keeping the assembly process simple through standardized fitting clearances.
3Manufacturing precision
If the fitting clearance between bearing portions and nozzle shaft is set to several tens of micrometers, then the assembly is precise, but wear occurs during operation causing non-smooth movement
Solution Approach 1:
The patent modifies the fitting clearance parameter from several tens of micrometers to several hundred micrometers. This parameter change reduces wear during operation, preventing non-smooth movement and improving reliability while still maintaining adequate positioning accuracy through the distributed bearing support configuration.
Data Source
AI summary
An inner surface of each first supporting hole of a shroud ring has on both sides in the axial direction of a turbine impeller two first bearing portions by which first nozzle shaft is rotatably supported. An inner surface of each second supporting hole of a nozzle ring has a second bearing portion by which a second nozzle shaft is rotatably supported. The fitting clearance between the second bearing portion and the second nozzle shaft is set larger than the fitting clearance between each of the first bearing portions and the first nozzle shaft.