Turbine Wheel Thread Structure for Turbocharger Scroll Leakage Control
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Solution Overview
Problem
In exhaust gas turbochargers with scroll passages divided in the circumferential direction, leakage of exhaust air from high-pressure to low-pressure passages can occur, reducing turbine efficiency due to inefficient gas flow through the turbine wheel.
Innovation Solution
The implementation of a thread or convex/concave object on the back-facing surface of the turbine wheel, extending towards the rotating shaft from the tongue sections, suppresses fluid passage between the back surface and the facing surface, preventing leakage and ensuring more exhaust gas passes through the turbine blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the scroll passage is divided into multiple pieces in the circumferential direction, then the turbine can handle variable exhaust gas flow, but exhaust air leaks from high-pressure to low-pressure passages through the back surface side, reducing turbine efficiency
Solution Approach 1:
The patent extracts and blocks the leakage path by adding a thread structure on the back surface of the turbine wheel. This thread protrudes into the gap between the turbine wheel back surface and the turbine housing, preventing exhaust air from leaking from high-pressure to low-pressure passages through the back surface side, thereby resolving the energy loss problem while maintaining the multi-piece scroll configuration
Solution Approach 2:
The thread structure acts as an intermediary element that fills and seals the gap between the turbine wheel back surface and the turbine housing. This intermediary structure prevents direct communication between high-pressure and low-pressure regions, eliminating the leakage path that would otherwise reduce turbine efficiency
Data Source
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AI summary
The present invention includes: a turbine wheel 24 that is attached to a rotating shaft 14 and that has a plurality of turbine blades in the circumferential direction; scroll passages 15Aa, 15Ab that are formed in a spiral shape on the outside of the turbine wheel 24, and that are formed by being divided into a plurality of sections in the circumferential direction, the passages communicating with each other at the position of the turbine wheel 24 disposed between respective tongue sections 15Ac, 15Ad; and threads 51 that are provided on an back facing surface 41 disposed so as to oppose the back surface of the turbine wheel 24, the back surface being on the axially opposite side from the turbine blade side, and the linear parts extending from starting points 51a near the tongue sections 15Ac, 15Ad toward the rotating shaft 14 side so as to control the passage of fluid between the back surface and the back facing surface 41.